Agenda packet — Santa Cruz City Council, June 24, 2025 (part 8 of 9)

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

Please provide any project related question or comment in the fields provided. Your comment/question will be automatically directed to the City Planner assigned to this project. Please note that questions and/or comments entered here are public information and subject to release in accordance with the Public Records Act.

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

Santa Cruz needs more housing. The laws of supply and demand are real. The more housing options that are available in Santa Cruz, the more affordable rents will be.

Thank you,
City of Santa Cruz

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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Thursday, April 24, 2025 4:48:57 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/24/2025 4:48 PM
Response #: 43
Submitter ID: 115871
IP address: 2601:647:c901:d40:29b9:f3ad:f3c7:6a93
Time to complete: 3 min. , 37 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

As resident in Santa Cruz I support more dense housing projects along transit corridors and close to downtown. Santa Cruz needs more transit accessible and walkable housing projects like this.

I hope the project is fully approved and built quickly. Please don't delay more desperately needed housing in Santa Cruz.

Thank you,
Jonathan Evans

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Santa Cruz, 95062
Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Tuesday, April 15, 2025 11:12:45 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/15/2025 11:12 PM
Response #: 23
Submitter ID: 115720
IP address: 2601:647:ca00:f2f0:31ca:5829:870f:2fe8
Time to complete: 4 min. , 17 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (831) 818-2727

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

I just want to express my support for these projects in my neighborhood. Some of my older neighbors have been mobilizing against these projects which I disagree with. As a parent and community member I want to express my gratitude to Santa Cruz for approving new developments and increasing our overall housing capacity, especially affordable housing.

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Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Tuesday, April 15, 2025 11:22:07 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/15/2025 11:22 PM
Response #: 24
Submitter ID: 115721
IP address: 2601:647:ca00:f2f0:d018:d38e:4ef4:4723
Time to complete: 9 min. , 52 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (831) 239-9341

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

Ocean st. Is currently a terrible mess that is squandering its potential as a neighborhood that can easily access the beach and downtown and seabright which is also one of the largest thoroughfares in the city.

We must develop ocean street into housing and shops and businesss that will be used by locals and tourists alike. It’s crucial that we proceed with developments like this one to meet our city’s housing needs. Ocean street is the perfect place for a large development like this because it provides easy access to downtown and so much more and is extremely bikeable and walkable limiting the need for cars. It’s also close to major bus routes that the traverse the county and go into Santa Clara county. There is an extremely vocal minority who wishes to keep Santa Cruz from changing and keep housing expensive. They don’t understand how

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much we need housing because they all own homes and the particular group that seems to oppose this development would have us think that ocean street is some sort of aesthetic marvel which is functional and frequented by locals. I live in the grant park neighborhood and I can walk to ocean street and aside from going to Marianne’s ice cream, I can’t count on one hand how often I’ve walked to, biked, or driven to a business on ocean street. It’s one of the ugliest streets in town and for being the welcoming street to our lively city it provides very little.

Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Thursday, April 17, 2025 10:42:33 AM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/17/2025 10:42 AM
Response #: 25
Submitter ID: 115742
IP address: 50.145.11.139
Time to complete: 13 min. , 46 sec.

Survey Details

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Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a question(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (183) 141-9747

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

I have concern about the privacy for my home and efacting our solar panels and power wall as well and safety of close to the wall and fair hazardous. Please consider all operations as well all so we have our business next to the project The Islander Motel we all so concern about privacy for our guests the windows on Motel side please look like it is against our fance as well we want our guests privacy please consider the as well.

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Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Thursday, April 17, 2025 2:52:01 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/17/2025 2:51 PM
Response #: 27
Submitter ID: 115749
IP address: 2601:647:ce02:5c20:a96c:9dd6:c2aa:7434
Time to complete: 5 min. , 59 sec.

Survey Details

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Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

I am very concerned that another high rise is in the planning stages. There are already 3 more in the works on Water St, at least one on Soquel and another big one on Ocean. I have not read any information re concerns about water, traffic, and parking which will definitely overflow into surrounding neighborhoods. I believe we need more time to evaluate the impact of the current construction and how well they rent, especially for low income families before more high density housing is approved. Thank you

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Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Monday, April 21, 2025 3:29:30 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/21/2025 3:29 PM
Response #: 29
Submitter ID: 115794
IP address: 207.53.252.154
Time to complete: 5 min. , 36 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

I support the project. Santa Cruz is in urgent need of more housing, and this development will provide 225 much-needed homes, including 39 affordable units.

The project also brings community benefits like new street landscaping, job creation, public space improvements, and funds to the City and County. The project will benefit everyone!

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Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Monday, April 21, 2025 3:35:40 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/21/2025 3:35 PM
Response #: 30
Submitter ID: 115795
IP address: 207.53.252.154
Time to complete: 4 min. , 20 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

Dear Santa Cruz Planning Commission,
I am writing to express my enthusiastic support for the 530 Ocean Street housing project. This development is a critical step toward addressing Santa Cruz’s housing shortage while delivering significant community benefits.

The project’s 225 residential units, including 39 affordable units for very low, low, and moderate-income residents, will provide much-needed housing options. The inclusion of 3,400 SF of commercial space, active

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tenant areas, and amenities like bike parking and an outdoor courtyard will enhance the vibrancy of Ocean Street.

Contributing $1.5M in development fees, $650,000 in annual property taxes, and $100,000 for the Branciforte Creek trail is a huge win for the city!
I urge the Commission to approve this project, as it aligns with Santa Cruz’s need for housing, economic growth, and environmental responsibility. Thank you for considering this transformative opportunity.

Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Monday, April 21, 2025 3:39:03 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/21/2025 3:38 PM
Response #: 31
Submitter ID: 115797
IP address: 207.53.252.154
Time to complete: 0 min. , 39 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

I am in support of this project
Thank you,
City of Santa Cruz

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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Monday, April 21, 2025 5:11:42 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/21/2025 5:11 PM
Response #: 32
Submitter ID: 115806
IP address: 207.53.252.154
Time to complete: 0 min. , 14 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

Not answered
Thank you,
City of Santa Cruz

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43.432
From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Tuesday, April 22, 2025 9:30:43 AM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/22/2025 9:30 AM
Response #: 34
Submitter ID: 115813
IP address: 2603:3024:1a0b:2800:210f:62e3:5307:b759
Time to complete: 2 min. , 15 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

I wanted to voice my support of this project. Santa Cruz is in need of housing and I fully support this project going through. It is on my commute into work and I'd love to see this get built.

Thank you,
City of Santa Cruz

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43.434
From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Monday, April 21, 2025 9:00:51 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/21/2025 9:00 PM
Response #: 33
Submitter ID: 115810
IP address: 98.51.172.158
Time to complete: 1 min. , 39 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

This project seems like a no brainer and big win for the community Thank you,
City of Santa Cruz

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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Tuesday, April 22, 2025 3:27:48 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/22/2025 3:27 PM
Response #: 35
Submitter ID: 115827
IP address: 2601:645:8a01:ee50:6994:34d:5fad:4322
Time to complete: 24 min. , 3 sec.

Survey Details

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Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

I am in support of this project. Santa Cruz County is experiencing a SEVERE HOUSING CRISIS, marked by high housing costs, low affordability, and homelessness. Median rents are above $3,000 per month which is blatantly unaffordable and there is a shortage of affordable housing options. Santa Cruz was ranked the least affordable rental market IN THE COUNTRY in 2023. This building helps to alleviate this crisis by creating 225 new housing units, including 39 affordable units. Many younger residents and students cannot afford to live in Santa Cruz due to this severe housing shortage and are forced to commute long distances or live in overcrowded conditions. Santa Cruz needs to prioritize the housing needs of the current and future populations of the city across ALL income levels.

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In addition to the above, the project will help to beautify the street, drive foot traffic, and create new jobs and tax revenue for the city. Approve this project!
Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Tuesday, April 22, 2025 4:04:36 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/22/2025 4:04 PM
Response #: 36
Submitter ID: 115828
IP address: 207.53.252.154
Time to complete: 2 min. , 40 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

Santa Cruz is in dire need of more housing. The limited availability has driven up rent prices, and this project will help with that pressure on all of us renters. Please approve this building.

Thank you,
City of Santa Cruz

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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Tuesday, April 22, 2025 4:08:43 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/22/2025 4:08 PM
Response #: 37
Submitter ID: 115829
IP address: 207.53.252.154
Time to complete: 12 min. , 44 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (510) 708-1579

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

We need more housing like this - housing that's available to those that make our City work and that give it our cherished character: teachers, artists, nurses, first responders, single parents, etc. The State needs more housing like this - infill, provides job, close to public transportation, + no negative impacts to the coastline or open space.

The project's design is also a significant and visible boost for this part of town. We should support forwardthinking architecture that responds to and uplifts its locations.

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My family and friends fully support this project. Pls approve!! Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Wednesday, April 23, 2025 9:55:43 AM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/23/2025 9:55 AM
Response #: 38
Submitter ID: 115840
IP address: 207.53.252.154
Time to complete: 6 min. , 1 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

I'm very excited to see this project bring 200+ units of desperately needed housing to Santa Cruz. There are few quality housing options in the area, and this project will help alleviate some of the supply shortfalls.

This project will also provide $1.5M in development impact fees and recurring property tax revenue, which the city can use to fund crucial fire, police, schools, childcare, parks and infrastructure. I am strongly in support of this project.

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Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Wednesday, April 23, 2025 12:31:01 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/23/2025 12:30 PM
Response #: 39
Submitter ID: 115842
IP address: 2600:1700:bb10:1920:adca:54cd:7d7d:9d9a
Time to complete: 15 min. , 12 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (415) 939-6255

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

When I was young, I used to frequent the Islander Hotel for affordable lodging relatively close to the Boardwalk. I have very fold memories of the Ocean St. corridor. I always recall thinking to myself that this section of Santa Cruz has such wonderful potential, but is without a solid identity. I pictured dense housing, retail, hospitality and much needed energy. Over the past 30 years, I have monitored the development of this neighborhood and have been saddened to see that it has not been enhanced much. The Hotel Paradox (which is now my lodging choice over the budget-friendly Islander) has truly enhanced this section of Ocean. I believe that 530 Ocean will continue this trend and hopefully lead to many more needed improvements of this corridor. A new, attractive building AND affordable housing? Why would anyone be

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against this?!
Thank you,
City of Santa Cruz
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43.446
From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Wednesday, April 23, 2025 9:53:03 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/23/2025 9:52 PM
Response #: 40
Submitter ID: 115854
IP address: 73.189.219.83
Time to complete: 1 min. , 16 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

I love the new housing
Thank you,
City of Santa Cruz

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43.448
From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Thursday, April 24, 2025 12:04:07 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/24/2025 12:04 PM
Response #: 41
Submitter ID: 115860
IP address: 2601:647:ce82:6c20:5cef:4786:a350:12b4
Time to complete: 5 min. , 20 sec.

Survey Details

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Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

This is a huge building that will dominate our backyards and property. It will reduce the value of our homes.

Six stories is way, way too high for this location. The City Council needs to stop developer greed and keep these developments to a maximum of three stories. Please do your job and push back and protect us from developer greed.

There is so much dense development going on in the downtown area. We don’t need more!!!

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Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Wednesday, March 5, 2025 5:12:53 AM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 03/05/2025 5:12 AM
Response #: 19
Submitter ID: 114990
IP address: 2601:647:ce00:3d10:c1c4:4f6d:82e2:244b
Time to complete: 9 min. , 4 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

The size of the 580 Ocean St project is incompatible with the existing single family homes surrounding it.

The solar study from the revised plans illustrates this as the huge six story complex covers the majority of the homes in the 100 block of May Ave in a shadow in the afternoon.

Every building in the plan should come down a couple stories to make it more compatible.

City planners mention the desire to bring increased access to the Branciforte creek foot path from Ocean St. I often pass people in the act of doing drugs or in a stupor from having used them while on the foot path, stolen bike parts and other goods litter the path. The Breakers apartments on the water street side of

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the path now have heavy chains with padlocks around their gated entrance that they once thought would afford their tenants access to the footpath. Instead it became a gateway for addicts and thieves to wreak havoc on their complex. Honor the delicate balance that those who live in this area have struck by not creating a corridor for additional foot traffic from Ocean street.

The existing infrastructure on Ocean street and Soquel Avenue cannot accommodate the many vehicles that will surely come with the residents of 225 new units. Most importantly, pedestrians will be further at risk. Crossing Soquel Avenue on foot as it is now is often a frustrating and unsafe endeavor. Secondary to this is the eyesore that will be created by the constant wall of cars that will line Ocean, Soquel and the smaller streets because residents have no where else to park. Additionally, there will be far less patrons to any businesses in the commercial space of the complex because they will know the difficulty with parking in the area.

The privacy of those living in the existing single family homes behind the proposed development will be severely affected. Revised plans mention removing several heritage trees and nothing of planting large trees in exchange to maintain the privacy of those who already call this area home.

We ask that you use your position as city planners to help preserve the safety and quaintness of Santa Cruz as well as advocate for those who have worked hard to live here.

Thank you,
City of Santa Cruz
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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Tuesday, March 4, 2025 4:55:40 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 03/04/2025 4:55 PM
Response #: 15
Submitter ID: 114979
IP address: 63.249.123.2
Time to complete: 26 min. , 41 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

Hello,
My comment regarding the housing development at 530-548 Ocean Street: Once again the city has approved a project that, while not ugly, has ZERO redeeming qualities. I favor additional housing and if it has to be high rise then fine. But these new residential buildings downtown and this one happening on Ocean Street detract from our community aesthetic--unless the goal was to make this the new aesthetic.

That's a shame! As well, we now have how many unnecessary square feet of high cost commercial space!! Can a local business pay the rent? So, guess we'll be filling this space with chain mega stores. Also a shame!

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I've commented several times over the past 6-7 years as these projects moved forward. I can only think the developers continue to be the only winners. What about the massive project next to Marianne's? Will this also be run-of-the-mill architecture? Please, build the housing but do better and demand better from the developers!
Thank you,
City of Santa Cruz
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43.454
From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Monday, April 14, 2025 8:24:27 AM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/14/2025 8:24 AM
Response #: 20
Submitter ID: 115681
IP address: 2601:647:ca00:9b40:c023:237:7f23:e571
Time to complete: 9 min. , 14 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

The project is absolutely too tall for the neighborhood. 2 or 3 stories should be the maximum height. Not only will it look bad and impact all the neighbors, but think in 20-30 years it will be a huge run down building. Older homes in the neighborhood have charm, older huge buildings will look like Queens in NYC.

No where for children to play in the apartments. Please reconsider the height, not the project itself, but 2-3 floors max.

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Thank you,
City of Santa Cruz
This is an automated message generated by Granicus. Please do not reply directly to this email.

43.456
From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Tuesday, March 4, 2025 8:27:22 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 03/04/2025 8:27 PM
Response #: 18
Submitter ID: 114986
IP address: 63.249.123.228
Time to complete: 1 min. , 12 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (831) 247-4510

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

To: Zoning Administrator
Re Project at 530,542, 548 Ocean St
From: Deborah Marks
207 Leonard St Santa Cruz CA 95060
831 247-4510

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I am a resident of the Central Park neighborhood which is adjacent to the proposed development at 530- 548 Ocean St . I am not able to attend this meeting because I work. I believe these meetings which are held to inform the community of a pending project approval should be held at a time when the residents of the neighborhoods impacted can attend. Since large scale residential projects like this one are now going through the Zoning Administrator meeting times need to accomodate the needs of residents who wish to participate. Also Zoning Administrator meetings need to be recorded for the interested people who are not able to attend.

While our neighbors welcome improvements and new housing on Ocean St we do have concerns about the impacts on our neighborhoods. Many of the residents who live here spent years working tirelessly with the City Planning Dept on the Ocean St Area Plan. One goal of this plan was to address adverse impacts of new development projects on neighborhoods along Ocean St adjacent to these developments . I personally was heavily involved in this effort for 8 years of my life. While we are aware State laws have usurped much of the City's power to design developments in the true spirit of scale and neighborhood compatibility, there are things that can be done to reduce the impacts and give our neighborhoods the privacy and dignity and respect they deserve. We are a neighborhood full of young families with young children who ride their bikes and play in the street. We have beautiful gardens and take much pride in our community. We know each other, help each other and love our beautiful historic homes and close neighborhood connections. We are a true community and we deserve protection for our neighborhood to the extent that the laws can allow.

Neighborhood Concerns and Requests:

CREEK PATHS:

The Branciforte Creek Pathway has long been a health and safety hazard for nearby residents of May Ave, Leonard St and Dakota. .

Before measures were in place for gates along the creek pathway that are locked at night and the section of trail from Ocean St to May Ave (Soquel Side of the creek) being permanently locked - our neighborhood residents were frequent victims of car thefts, theft of car contents, home thefts, home break ins, piles of feces left in public areas, a plethora of trash left in the public streets and on private property. Our residents were put in harm's way due to w needles left on public and private property and we were exposed to verbal and physical threats from aggressive frightening individuals.

Things are far from perfect now but the safety measures in place along the creek have made a huge positive impact and must be maintained for the safety of the many young children and adults in our little community. We cannot return to this dangerous situation of the past . If a trail from Ocean St to May Ave is left open it will quickly turn into a homeless encampment and create fear, anxiety and insecurity for all who live here. We cannot return to this dangerous situation.

Requests:

Gates along the trails on both sides of the Creek need to be locked at night as they are now.

Gates on the trail portion between Ocean and May is now locked all the time it needs to remain locked.

DELIVERIES:

Online orders and for commercial supplies will result in a continuous stream of deliveries. What accommodations are being made for delivery trucks.? This will create a safety hazard and block traffic on Ocean St. where traffic issues are already extremely problematic.

Suggestions: No deliveries allowed during peak traffic hours. A designated place for delivery trucks to park on Ocean St.

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SCREENING:

Where feasible tall vegetation for screen on the rear side of the building facing may Ave and the side of the building facing the Creek. Replacing the trail from Ocean St to May with tall attractive trees would be a good solution.

PARKING:

It goes without saying that adding 225 apartments and a level of commercial use with only 80 parking spaces and no public parking lots close by will be a parking disaster that will overwhelm our small residential streets of May Ave, Leonard St and Dakota . People looking for parking will be cruising the streets looking for parking. Many of us do not have off street parking and we will no longer be able to park near our homes and we will have no place to go. since there are no nearby streets.

Fortunately, there is a perfect solution. We know the City has a program for getting parking permits. The City needs to create a fast track process for the impacted residents to get parking permits on an immediate emergency basis. We are aware the Planning Department does not issue parking permits but this could be made a condition of approval on the project to allow residents of these streets heavily impacted by the new project to get their permits processed on an emergency basis. Residents pay for parking permits so it generates revenue for the City.

There is precedent in the City for a somewhat similar accommodation. After a big storm that closed part of Westcliff Drive ,the City responded to the neighborhoods near Westcliff Drive. Residents were bothered by the additional recreational traffic on their usually quiet streets, the city responded immediately by constructing barriers all over the area to create a multitude of dead end streets allowing Westcliff Drive residents to retain their peaceful neighborhoods. The City reacted quickly and bypassed the usual public works process to accomodate the needs of these residents. Similarly, for our neighborhood the addition of 225 units plus commercial space with minimal parking will be an emergency situation for these tiny narrow streets that cannot accommodate the added traffic and parking.

We Request to the City to direct Public Works to allow an immediate process to get parking permits for these impacted neighborhoods:

New parking permits for May Avenue on Soquel Side of Creek per neighborhood request.

Extension the the hours and days of the parking permit program on the Water St side of the Creek. which is Central park neighborhood- Leonard St, May Ave and Dakota per neighborhood request.

Commercial uses are a big issue. It should be something that serves the neighborhood and to make Ocean St a more walkable , more lively community friendly street. No noisy bars, loud music venues, marijuana outlets, alcohol outlets, chain /fast food restaurants. Our residents would happily continue a discussion on what might be a good fit with the applicant.

Thank you,
City of Santa Cruz
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43.459
From: Deborah Marks
To: Rina Zhou
Subject: Project at 530, 542, 548 Ocean St
Date: Tuesday, March 4, 2025 8:17:33 PM
****CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.**** To: Zoning Administrator
Re Project at 530,542, 548 Ocean St
From: Deborah Marks
207 Leonard St Santa Cruz CA 95060
831 247-4510
Iam a resident of the Central Park neighborhood which is adjacent to the proposed development at 530-548 Ocean St . I am not able to attend this meeting because I work. I believe these meetings which are held to inform the community of a pending project approval should be held at a time when the residents of the neighborhoods impacted can attend. Since large scale residential projects like this one are now going through the Zoning Administrator meeting times need to accomodate the needs of residents who wish to participate. Also Zoning Administrator meetings need to be recorded for the interested people who are not able to attend.

Neighborhood Concerns and Requests:

CREEK PATHS:

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The Branciforte Creek Pathway has long been a health and safety hazard for nearby residents of May Ave, Leonard St and Dakota. .

Before measures were in place for gates along the creek pathway that are locked at night and the section of trail from Ocean St to May Ave (Soquel Side of the creek) being permanently locked - our neighborhood residents were frequent victims of car thefts, theft of car contents, home thefts, home break ins, piles of feces left in public areas, a plethora of trash left in the public streets and on private property. Our residents were put in harm's way due tow needles left on public and private property and we were exposed to verbal and physical threats from aggressive frightening individuals.

Things are far from perfect now but the safety measures in place along the creek have made a huge positive impact and must be maintained for the safety of the many young children and adults in our little community. We cannot return to this dangerous situation of the past .If a trail from Ocean St to May Ave is left open it will quickly turn into a homeless encampment and create fear, anxiety and insecurity for all who live here. We cannot return to this dangerous situation.

Requests:

Gates along the trails on both sides of the Creek need to be locked at night as they are now.

Gates on the trail portion between Ocean and May is now locked all the time it needs to remain locked.

DELIVERIES:

Suggestions: No deliveries allowed during peak traffic hours. A designated place for delivery trucks to park on Ocean St.

SCREENING:

PARKING:

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be made a condition of approval on the project to allow residents of these streets heavily impacted by the new project to get their permits processed on an emergency basis. Residents pay for parking permits so it generates revenue for the City.

The City reacted quickly and bypassed the usual public works process to accomodate the needs of these residents. Similarly, for our neighborhood the addition of 225 units plus commercial space with minimal parking will be an emergency situation for these tiny narrow streets that cannot accommodate the added traffic and parking.

We Request to the City to direct Public Works to allow an immediate process to get parking permits for these impacted neighborhoods:

New parking permits for May Avenue on Soquel Side of Creek per neighborhood request.

Extension the the hours and days of the parking permit program on the Water St side of the Creek. which is Central park neighborhood- Leonard St, May Ave and Dakota per neighborhood request.

I wish to thank Rina and Lisa for taking the time to speak with me yesterday and listen to the concerns of my neighbors.

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From: Don Landes
To: Rina Zhou
Subject: Re: 530 Ocean St Question/Comment Received
Date: Wednesday, March 5, 2025 2:20:28 PM
Attachments: image001.png
****CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.**** Thank you Rina:

I did attend the hearing this morning, & spoke, as did my wife Deborah Marks--we have lived( 40 yrs)
in the very nearby, across the creek, area called Central Park.

We do painfully understand about the State Bonus Density Law that controls some of the issues. I just want to make
sure that the Planning Dept isn't "piling on" with their own added ideas & agenda. And I do hope that the city can push back
at the state whenever possible to protect fragile neighborhoods, like ours, so close to commercial.

And I have heard, and got to believe, w/ the onslaught of large projects, that city has met it's housing obligation
with state re: number of residential units. If that is the case, does the State Bonus Density Law still rule, or is null if the city
has met the minimum requirement?
Also, re: parking: with only 85 or so parking spots, which seems to be only one third of the necessary, it's a big issue.

And it seems that the Administrator is saying: re: permits, just go to public works and figure it out for yourselves--good luck.

That's not right--the developers seem to say that the reason they don't have more parking is because of Planning
requiring more commercial space.

Here's the way I look at it: the developers and Planning working together negotiated this number of parking spaces for whatever reasons--which is not enough--that was their joint decision. So why
should the neighborhood suffer at all with any parking problems generated by the project? For this reason I believe
it's not right just send us to Public Works and say "good luck"; but Planning Dept should help us with getting parking permits.

Also, I know that at least two of the owners on May St. , living directly in back of the project , couldn't be at the
hearing because of work. It really sends a bad message to the neighborhood to have a hearing at that time, instead
of in the evening.

Finally, instead robust interactions with the Planning Commission and the City Council where we can plead our case in front of elected officials-- when large projects can be decided by a

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lone
Zoning Administrator, it is essential to counter-balance this fast-tracking by having more community outreach
not less, which happened this case....a bare minimum.

Don Landes. 831-247-4508
On Wed, Mar 5, 2025 at 9:52 AM Rina Zhou <[email protected]> wrote:

Good morning,
Thank you for your email and comments. They were forwarded to the Zoning Administrator for review and also posted to the Agenda Packet. This project is subject to State Density Bonus Law (which allows for waivers and incentives/concessions to waive/vary from the Municipal Code), Housing Accountability Act, Senate Bill 330 as well as the objective standards. I also wanted to provide some information regarding the General Plan policies and the vision for the Ocean Street corridor. The subject properties are zoned C-C (Community Commercial) which encourages a harmonious mixture of a wide variety of commercial and residential activities, and designated as MXVC (Mixed-Use Visitor Commercial), which encourages high-quality visitor serving commercial development. The higher density mixed-use projects such as this are envisioned to be along the major corridors, like Ocean Street.

Please let me know if you have any questions.

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From: [email protected] <[email protected]> Sent: Tuesday, March 4, 2025 9:22 AM
To: Rina Zhou <[email protected]>
Subject: 530 Ocean St Question/Comment Received
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 03/04/2025 9:21 AM
Response #: 14
Submitter ID: 114958
IP address: 63.249.123.228
Time to complete: 13 min. , 25 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a question(s).
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]

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Phone: (831) 247-4508

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

1. Why no setbacks-? why can the structures go right up to the property lines of the May Ave. residential properties? Is this required by the recent state laws? Comment: it seems that the city always shunts the blame on the recent state laws-- Objective Standards/Density Bonus.... how much of this project due to state laws and how much is merely additional Planning Dept policies?

2.. The timing of Wed. 10 a.m. Zoning Admin. hearing is a slap in the face to the working people on May Ave. who will have this project right up to their property lines.

I know of a least three of those residents having deep concerns who cannot attend the zoning hearing because they have to be at work.

Setting a meet at this time will have the appearance that the Planning Dept. is just going thru the motions--"checking the box"-- minimizing the input of concerned citizen--neighbors, greatly impacted by this project.

3. Looking at the larger picture, this is one of several large projects surrounding my nearby neighborhood of Central Park(just across the creek)--all within 2 or 3 blocks, and impacting several other fragile neighborhoods on the near East side, already so close to existing commercial:

Examples: 908 Ocean : 389 units
the huge project at Branciforte & Water, a large project on Soquel Ave. and several others

4. This begs the question: does City Planning respect the small fragile neighborhoods on the near East Side(presently bombarded with large projects); and is the Planning Dept. committed to protecting them?; or is the City more aligned with the terminology where our area is now referred to as "Mid-Town"-- a move towards multi-use/multi-story building & the loss of single residential housing?

5. Comment: although City Planning seems to spend much of their time dealing with the multitude of large-multi-story, multi-unit projects, City Planning should also work to protect & promote the old time small neighborhoods being impacted:
e.g. my house & many close by were built over 100 years ago.

6. Thank you for listening
Thank you,

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City of Santa Cruz
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43.467
From: Jennifer Merchant
To: Rina Zhou
Cc: Dave Mitchell
Subject: 530, 542, 548 Ocean St.

Date: Wednesday, March 5, 2025 7:14:28 AM
****CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.**** March 5, 2025
Good morningI realize this is a late message but am new to the neighborhood and did not receive public notice for the Zoning Administrator hearing. My residence is at 235 May Ave.

I have concerns about the height and massing of this project that will shadow a mostly single family, single story residential neighborhood.

The project is out of compliance with the existing community plan and not in the scale or character of the existing neighborhood.

Further, the lack of parking will strain existing parking shortage in neighboring streets. Please consider limiting onstreet parking to permit only on Ocean St and excluding neighboring May, Dakota and Leonard.

Finally, perhaps I am somehow missing it but do not see that the project includes any affordable housing. I hope I am wrong. To co-opt a corny “Arthaus” name without making housing available to creatives and other Santa Cruzans being pushed out because of over-bloated monoliths such as this would be a travesty.

Density bonus without affordability does not a vibrant community make.

Best,
Jennifer Merchant
Homeowner

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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Tuesday, March 4, 2025 8:03:05 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 03/04/2025 8:02 PM
Response #: 17
Submitter ID: 114984
IP address: 2a09:bac2:b02d:1246::1d2:28
Time to complete: 6 min. , 21 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (831) 888-6840

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

Hi, as a homeowner in the central park neighborhood, I am concerned about the lack of communication regarding this project. we understood from previous meetings that the developer would reach out to our neighborhood to have discussions and share information regarding the project. I have not received any notification or communication from the developer. I will be attending the meeting tomorrow and want to learn more and have a chance to give feedback to help benefit the neighborhood:
than you,
Leslie Wooding

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Thank you,
City of Santa Cruz
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43.470
From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Tuesday, March 4, 2025 7:57:57 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 03/04/2025 7:57 PM
Response #: 16
Submitter ID: 114983
IP address: 71.204.131.227
Time to complete: 7 min. , 12 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a question(s).
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (505) 930-4120

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

Hello. I live at 126 May Avenue and attending the Community Meeting in May of 2024. I have some comments and concerns I'd like to see addressed.

1. After the May 2024 community meeting there was supposed to be followup with the neighborhood residents, and I never received any further communication, letters, or invitation to discuss the plan further.

2. The scope of the plan changed adding height (4 to 6 stories), and additional units. There was no

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community meeting the communicate the change in plan.

3. What is the plan for delivery vehicles such as Amazon, UPS, Uber trucks servicing 225 units? Has this been considered within the traffic studies?

4. I am supportive of additional housing projects in Santa Cruz, but the scale of this project does not integrate well with the surrounding 1 story residential neighborhood. How does the scale of this project fit within the Ocean Street Area Plan?

5. Parking. From my understanding there are 80 parking spots in the plan which exceeds the requirement.

But realistically where are people going to park when there are couples, both with cars, occupying single occupancy units and most tenants will have cars. It is not realistic to think people wont have cars just because it’s in a metro transit zone.

6. I would like to have some time to review the plan and meet with the developer before this project approval proceeds.

Thank you,
City of Santa Cruz
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43.472
From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Friday, April 18, 2025 2:39:43 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/18/2025 2:39 PM
Response #: 28
Submitter ID: 115773
IP address: 63.249.123.228
Time to complete: 14 min. , 47 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a question(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (831) 247-4510

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

I know shadow studies were done from the Ocean ST side of the building? But Have shadow studies been done on the Creek side of the building? and the Hotel side? What is the shading situation for the single family homes on the opposite side of the creek on May and Dakota? also
Will noise be generated from the mechanism in the garage that moves the cars? Is the garage thoroughly sound proofed .

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Will my questions be posted anywhere for others to see them and the answers? Thank you,
City of Santa Cruz
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43.474
From: Rina Zhou
To: [email protected]
Subject: RE: 530 Ocean St Question/Comment Received
Date: Thursday, April 24, 2025 6:00:00 PM
Attachments: image001.png
Good afternoon,
Thank you for your email! These have been added to the public record and were also forwarded to the project applicant so they are aware of the comments. Regarding your first question, I wanted to clarify that map is only referenced in the applicant’s community meeting presentation so it’s not a map that the City uses in their review. I have noted in the Zoning Administrator staff report that there are residential uses located east of the subject properties and made references to the single-family homes facing the rear façade of the proposed project as well.

I also wanted to clarify that the 525 Water St project is a 100% affordable housing project with different funding constraints. For market-rate projects with affordable housing units, they are required/strongly encouraged to meet all the requirements in the City’s Municipal Code. The General Plan outlines the vision of land use and planning in the City as a whole, with the Ocean Street Area Plan providing further goals and policies for developing in this area. High density mixed-use developments are envisioned for the Ocean Street corridor. New buildings on Ocean Street will provide space for a variety of local businesses, as well as create new places to work, live and visit.

Omitting the ground floor commercial space would not be in keeping with the General Plan and Ocean Street Area Plan policies, or the objective design standards which requires active frontage in the C-C zone district. Additionally, the ground floor commercial space is intended to serve the local neighborhood (i.e. walking distance to people living nearby) and should be beneficial to the community. The applicant has also requested a density bonus waiver to waive the height and FAR requirement, and so the City is not able to require that the applicant redesign the project to be less tall per State Law.

Please let me know if you have any questions.

43.475
From: [email protected] <[email protected]> Sent: Thursday, April 17, 2025 10:46 AM
To: Rina Zhou <[email protected]>
Subject: 530 Ocean St Question/Comment Received
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/17/2025 10:45 AM
Response #: 26
Submitter ID: 115743
IP address: 2603:3024:204:5300:1446:1de6:8759:3ad1
Time to complete: 8 min. , 19 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support with Concerns

4. Question/Comment:

1. In the presentation "ArtHaus Ocean-Community Meeting Presentation", page 11 Site Map, that shows the surrounding neighborhoods with labels. This map omits a "Single Family Neighborhood" annotation for the May Avenue neighborhood directly behind the project. Is it possible to update this map to accurately reflect that it is NOT "commercial" behind the project so its not misleading?

2. I'm specifically concerned about the scale/height of the project not blending in with surrounding Single

43.476
Family Neighborhood (and eclipsing south daylight for a whole neighborhood block). The project shows that the first floor is slated for commercial space. Can we discuss options of omitting commercial space on the first floor and potentially reducing the project height by one story? This was a recently approved proposition for the 525 Water street project.

Thank you!
Thank you,
City of Santa Cruz
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43.477
From: Rina Zhou
To: Deborah Marks
Subject: RE: 530 Ocean St Question/Comment Received
Date: Thursday, April 24, 2025 6:09:00 PM
Attachments: image001.png
Shadow Study.pdf
More Detailed Shadow Study.pdf
Hi Deborah,
Thank you for your email! Regarding the shading question, please see attached for the shading study that was submitted as part of the project. The applicant also followed up with a more detailed shading study as well, please see attached.

Regarding the question about the parking stackers in the garage, the applicant will need to submit the noise specifications for the parking stackers at the building permit stage for staff to review to ensure compliance with the Noise Performance Standards in the Municipal Code. The parking stackers are located within a parking garage that is surrounded by concrete. It is a great question and I’ve followed up with the applicant to see if they can provide more specific information regarding this as well.

Your questions and the answers to them will be posted in the Planning Commission Agenda Packet under public correspondence.

Please let me know if you have any further questions.

Best regards,
Rina
Rina Zhou, RPP, MCIP
Senior Planner
City of Santa Cruz | Planning and Community Development Department 809 Center Street, Room 101, Santa Cruz, CA 95060
Direct: 831-420-5104 | Main Line: 831-420-5110
Email: [email protected]
Web: cityofsantacruz.com
From: [email protected] <[email protected]> Sent: Friday, April 18, 2025 2:40 PM
To: Rina Zhou <[email protected]>
Subject: 530 Ocean St Question/Comment Received
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street

43.478
Date & Time: 04/18/2025 2:39 PM
Response #: 28
Submitter ID: 115773
IP address: 63.249.123.228
Time to complete: 14 min. , 47 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a question(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (831) 247-4510

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

Will my questions be posted anywhere for others to see them and the answers? Thank you,
City of Santa Cruz

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This is an automated message generated by Granicus. Please do not reply directly to this email.

43.480
From: Rina Zhou
To: [email protected]
Subject: RE: 530 Ocean St Question/Comment Received
Date: Wednesday, April 16, 2025 4:58:00 PM
Attachments: image001.png
Good afternoon,
Thank you for your email! To answer your questions, the General Plan outlines the vision of land use and planning in the City as a whole, with the Ocean Street Area Plan providing further goals and policies for developing in this area. High density mixed-use developments are envisioned for the Ocean Street corridor. By the year 2030, the vision for Ocean Street is that it will become a beautiful, multifaceted gateway to Santa Cruz that reflects the city’s unique and diverse character. New buildings on Ocean Street will reflect a high caliber of architectural design. They will provide space for a variety of local businesses, and they will create new places to work, live and visit.

With regards to water availability, projections for the City’s growth are included in the City’s water supply planning. Due to modern water efficiencies and Santa Cruz’s commitment to conservation, the modest growth in water demand that’s projected does little to increase our need for water supply.

Santa Cruz has had water shortages for the last several decades, driven by droughts. Even with 30% growth since the 1980s, we’re using approximately the same amount of water now as we were then, thanks to conservation efforts including plumbing code changes and water efficient appliances and landscapes. With regards to traffic, the City evaluates trips per project. A Traffic Impact Study was submitted to the City and reviewed by the Public Works Department for the 530 Ocean St project with no concerns from staff. The Public Works Department reviews all development projects and provides comments related to sewage and trash.

Please let me know if you have any questions.

Best regards,
Rina
Rina Zhou, RPP, MCIP
Senior Planner
City of Santa Cruz | Planning and Community Development Department 809 Center Street, Room 101, Santa Cruz, CA 95060
Direct: 831-420-5104 | Main Line: 831-420-5110
Email: [email protected]
Web: cityofsantacruz.com
From: [email protected] <[email protected]> Sent: Monday, April 14, 2025 5:16 PM
To: Rina Zhou <[email protected]>
Subject: 530 Ocean St Question/Comment Received

43.481
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/14/2025 5:16 PM
Response #: 21
Submitter ID: 115702
IP address: 73.70.172.209
Time to complete: 5 min. , 6 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a question(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (831) 426-6318

3. Please select one of the following regarding the nature of your comment:
(○) Concerns

4. Question/Comment:

How does this and all the other proposed high density buildings work in such a small area of our town when all are built. How will the summer tourist traffic work? What about water supplies, sewage, trash. Santa Cruz is already struggling with these issues. The proposed high density does not seem to be supported by our already over taxed infrastructure. This all needs to be looked at as a whole, is anybody doing that? Thank you,
City of Santa Cruz

43.482
This is an automated message generated by Granicus. Please do not reply directly to this email.

43.483
From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Monday, April 14, 2025 10:52:40 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/14/2025 10:52 PM
Response #: 22
Submitter ID: 115707
IP address: 2a09:bac2:657e:123c::1d1:60
Time to complete: 6 min. , 42 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (206) 902-8403

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

I don’t normally write into measures before the city, But I lived on Ocean St for 3 years in the 180 Dakota building. I am completely in favor of building more housing in Santa Cruz, esp high density housing to alleviate the pricing pressure for renters as a whole. I understand there may be some concerns with traffic etc. but giving people more opportunities for places to live in Santa Cruz is better for everyone in the long run. I am still a Santa Cruz renter and am strongly in favor of making Santa Cruz more accessible by building more homes for people to live in.

43.484
Thank you,
City of Santa Cruz
This is an automated message generated by Granicus. Please do not reply directly to this email.

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From: [email protected]
To: Rina Zhou
Subject: 530 Ocean St Question/Comment Received
Date: Saturday, April 26, 2025 7:43:48 PM
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 04/26/2025 7:43 PM
Response #: 44
Submitter ID: 115892
IP address: 2001:5a8:4569:4900:6d0d:529:2a13:be7c
Time to complete: 32 min. , 5 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071).

1. Select what applies:
[×] I have a comment(s).

2. If you have a question that needs a response, please enter your email address or phone number.

Email: [email protected]
Phone: (650) 380-3798

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. Question/Comment:

Hi! I lived in Santa Cruz from 2020-2024 and am a huge advocate of affordable housing and greater urban density. Please consider the future of our city and do what you can do help more folks, especially those without great fortunes to share and build in our vibrant community.

Thank you,

43.552
City of Santa Cruz
This is an automated message generated by Granicus. Please do not reply directly to this email.

43.553
1 Rina Zhou
Subject: RE: Item 4 - 530, 542 548 Ocean Street Project - Fw: Exhibit A Conditions for 500 Ocean St., No 99-023
From: eric grodberg <[email protected]>
Sent: Thursday, May 1, 2025 6:15:37 PM
To: City Plan <[email protected]>
Cc: Leslie Keedy <[email protected]>; Eric Grabiel <[email protected]> Subject: Item 4 - 530, 542 548 Ocean Street Project - Fw: Exhibit A Conditions for 500 Ocean St., No 99-023

****CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.****
Greetings Chair Polhamus and Planning Commissioners,
I own 115 May Avenue which is not directly touching the project under discussion tonight.

In 1999 the Best Western Hotel at the corner of Ocean and Soquel received approved for a major expansion. The north wall of the project is a flat (no building articulation at all) 3 story wall with many windows that look directly into my yard.

The Zoning Administrator was aware of this and as part of the Conditions of Approval required, ""The ZA indicated that the only remaining issue is to focus more on the landscaping. One of the things discussed is breaking up the north wall. There is a need to see something more substantial with evergreen trees. ..." (see original doc attached p.3)
To date, more than 25 years later, the Hotel is still out of compliance. I have worked with the City Arborist, Leslie Keedy, over the years and she has been very helpful, but has limited power.

The City has declined to take stronger measures against the Hotel to force compliance.

If the Ocean Street project is approved, I hope that the City will use its full power to ensure compliance with any Conditions of Approval, especially those that could mitigate harms to existing neighbors.

Respectfully,
-Eric Grodberg
----- Forwarded Message -----
From: eric grodberg <[email protected]>
To: [email protected] <[email protected]>
Sent: Thursday, May 1, 2025 at 05:59:49 PM PDT
Subject: Fw: Exhibit A Conditions for 500 Ocean St., No 99-023 ----- Forwarded Message -----
From: eric grodberg <[email protected]>

43.554
2 To: Leslie Keedy <[email protected]>; Jenna Wilson <[email protected]> Sent: Thursday, February 28, 2019 at 09:37:42 AM PST
Subject: Exhibit A Conditions for 500 Ocean St., No 99-023 Hi Leslie,
I'm sorry. I thought that you were working directly off the City document - Conditions Exhibit A Conditions for 500 Ocean St., No 99-023. I have forwarded an old email that has it attached. Note that on page 3, it states:
"The ZA indicated that the only remaining issue is to focus more on the landscaping. One of the things discussed is breaking up the north wall. There is a need to see something more substantial with evergreen trees. ..."
As I wrote in my prior email, what they've planted is neither substantial, nor does it break up the north wall. I don't see how they have complied - especially after being 20 years late.

Also on Page 1, Item 11 refers to and discusses requirements of a landscaping plan. The requirements include • minimum 15 gallon size trees
• permanent maintenance
• fully automated irrigation
The current plantings don't meet these requirements.

Thanks,
-Eric
On Thursday, February 28, 2019, 8:47:33 AM PST, Leslie Keedy <[email protected]> wrote:

HI Eric, as I work in Parks -can you please provide Jenna & me with all of the written conditions & approval language that you are privy to & reading from so she & I can understand what our clear authority is in this case. We as staff need to reasonably interpret what has been written & approved, we have no authority past that even if it seems reasonable to you, staff cannot mandate above & beyond what was approved & the written expectation so anything you have for our enforcement consideration will be helpful. Thanks L
----- Forwarded Message -----
From: eric grodberg <[email protected]>
To: Martin Bernal <[email protected]>
Sent: Wednesday, October 3, 2018, 12:21:10 PM PDT
Subject: Fw: Corridor rezoning and 500 Ocean St (Best Western) Martin,
For Background - one of the issues I want to discuss with you tomorrow. My attempts to deal with this through normal channels have gone on for more than 15 years.
-Eric
----- Forwarded Message -----
From: eric grodberg <[email protected]>

43.555
3 To: [email protected] <[email protected]>; Leslie Keedy <[email protected]> Sent: Saturday, March 18, 2017, 9:04:48 AM PDT
Subject: Corridor rezoning and 500 Ocean St (Best Western) Hello Michelle,
I own 115 May Avenue, - the backyard abuts a commercial Ocean Street lot, and the side yard is the third lot from the corner of Soquel.

In 1999 the Best Western received a permit for expansion along Ocean Street. To date, the hotel has still not complied with the Conditions of Approval (attached.) I object to any beneficial rezoning (as part of the Corridor Rezoning) of this property until the owners comply with the terms of the the 1999 Conditions.

Over the years I have made numerous complaints to both City officials and Hotel Management. These include Mike Ferry, Leslie Keedy, Linda Garner, former Mayor Lynn Robinson and others.

Mike wrote them two letters demanding compliance, which they ignored. Linda prompted them to clean up some debris. Leslie has made numerous attempts to make them comply with the planting requirements along the north wall and I greatly appreciate her efforts, but to date, they have not been successful. Although there are other issues of non-compliance, the my greatest concern is the landscaping of the Hotel's north wall.

The Hotel's inaction has a material and significant negative effect on my property. I would welcome the chance to meet with you to finally resolve this issue. You can also contact Leslie for background. If you think this would be more properly handled by another member of the Planning staff, please direct me to that person.

I have long email chains documenting my (and City Officials') efforts at resolving this. I have included in this letter just a short one that includes the Conditions of Approval as attachments.

Thanks.

Sincerely,
Eric Grodberg
831-334-1705

43.556
4 ----- Forwarded Message -----
From: eric grodberg <[email protected]>
To: Leslie Keedy <[email protected]>; "[email protected]" <[email protected]> Sent: Wednesday, February 19, 2014 8:01 AM
Subject: Conditions 500 Ocean St
Hi Leslie,

Attached is "Exhibit A" Conditions for 500 Ocean St., No 99-023. My scanner is down, so I took photos of the pages. My apologies for the quality. I can come by your office today with the document.

A few items to note:

1. Page 3: "The ZA indicated that the only remaining issue is to focus more on the landscaping. One of the things discussed is breaking up the north wall. There is a need to see something more substantial with evergreen trees. ..."

2. Page 1, Item 11 refers to and discusses requirements of a landscaping plan.

3. Page 2, Item 22. I know that this is not in your ambit, but they did not comply with the screening requirements on the North side of the building - the side I'm concerned with. I'll send photos documenting this in a separate email.

Thanks so much. I greatly appreciate your help!

-Eric
From: Leslie Keedy <[email protected]>
To: "'[email protected]'" <[email protected]> Sent: Tuesday, February 18, 2014 4:51 PM
Subject: email address
Hi please email me info as you find it, happy to help L

43.557
1 Rina Zhou
Subject: RE: Meeting with Diaz Capital
From: Deborah Marks <[email protected]>
Sent: Tuesday, May 20, 2025 10:57
To: Gabriela Trigueiro <[email protected]>
Subject: Re: Meeting with Diaz Capital
****CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.****
Thank you Gabriela,
We will be meeting with Diaz Capital again, probably next week. I do hope they can make a few changes to in some way comply with the spirit of the OSAP for neighborhood compatibility. An 80 foot tower with a solid blank 20 foot wall at the property line is such a seriously extreme and mean impact. It may not be part of the state laws, but an ambitious developer who wants as much business as they can get in this community and claims to care about Santa Cruz should be able to create a project with some sensitivity to the neighbors whose lives will be very diminished by a building of this size and design. Other developers have softened their projects to decrease some harsh impacts. I hope Diaz Capital can develop some empathy for our neighborhoods' concerns and find a way to keep our adjoining neighborhoods liveable.

On another but related topic...There is an important issue that perhaps the City Council can look into.

People who signed up for email updates on the 530 Ocean St project website never got updates on the progress of the project. I had this same experience with not getting email notifications other City meetings after I signed up online for notifications. This happened to me with 530 Ocean and with other issues I was following as well. I don't think the system works, at least not consistently. Such Lack of notification really cuts down community involvement. And like with 530 Ocean St this allowed the project to progress and be passed with one Zoning Administrator meeting and no input from the community for the many months that followed the initial community meeting in May 2024. A I am sure you are well aware, people are so busy and are just struggling to survive. If they don't get notifications it is out of sight out of mind. I don't think this is what the City intended when they set up this type of system for approving significant impact projects. .

Thank you again for taking an interest in our neighborhood.

Best, Deborah
On Mon, May 19, 2025 at 9:59 AM Gabriela Trigueiro <[email protected]> wrote:

Hi Deborah,

43.558
2 Thank you for including me in last week's meeting with Diaz - I really appreciate your time coordinating this and giving your thoughts!
Thanks also for showing up to last week's city council meeting - that was a late night and it was really meaningful to see so many residents be present.

In community, Gabriela
Gabriela Trigueiro
she / her / ella
Councilmember
Santa Cruz City Council
809 Center Street, Santa Cruz, CA 95060
Email: [email protected]
Web: cityofsantacruz.com
From: Deborah Marks <[email protected]>
Sent: Thursday, May 8, 2025 11:34
To: Sonja Brunner <[email protected]>; Gabriela Trigueiro <[email protected]> Cc: leslie wooding <[email protected]>; Eric Grabiel <[email protected]>; Ryan Bailey <[email protected]>
Subject: Meeting with Diaz Capital
****CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.****
Hi Sonja and Gabriela,
We have set up a zoom meeting with Lisa Vilhauer for May14th 530 pm. It will be very helpful if you could participate in this meeting.

Thanks for getting this going. I think it would be very helpful for our group to speak to each of you ahead of time for some guidance and tips on how best to use this meeting to benefit our neighborhoods. We know there have been some positive outcomes with other project developers, ie the ones on 525 Water and 903 Ocean. Your knowledge and experience would be greatly appreciated as we move forward.

I am available for a phone call today, I'll be away for the weekend starting tomorrow but back on Monday. My time is very flexible today and next week.

I look forward to speaking with you soon.

43.559
3 Thank you, Deborah Marks
207 Leonard St
831 247-4510

43.560
June 16, 2025
Via email: [email protected]
TO: City of Santa Cruz City Council
809 Center Street
Santa Cruz, CA 95060
RE: Response to Supplement to Eric Grabiel’s Appeal of Planning Commission Approval of Development Project No. CP24-0071 at 530, 542, and 548 Ocean Street Dear Council Members,
We represent Ocean Street Santa Cruz LLC (“Project Applicant”) and hereby provide a response to the appeal of Eric Grabiel (“Appellant”) submitted by Appellant’s counsel on May 9, 2025 (“Appeal”). As discussed herein none of the issues presented in the Appellant’s letter raise a legal or factual basis as to why the proposed Project is not categorically exempt. The Project is categorically exempt from review under the California Environmental Quality Act (“CEQA”) based on substantial evidence in the Project record and was appropriately approved by the Zoning Administrator and appropriately upheld by the Planning Commission at its hearing on May 1, 2025 (“Planning Commission Hearing”). We note that many of the issues raised in the Appeal are identical to the issues Mr. Grabiel raised to the Planning Commission so much of our response is repetitive of the response we sent to the City on May 1, 2025.

A. The City Can Issue a Permit for the Removal of Heritage Trees on Adjacent Property Owners’ Property with Permission.

As was the case before the Planning Commission, the Project design has been revised to avoid the removal of one of the heritage trees cited by commenter: the heritage tree located at 129 May Avenue, which is Mr. Grabiel’s property. The tree located at 134 May Avenue will need to be removed. As indicated in the Staff Report for the Planning Commission Appeal (“Planning Commission Staff Report”), the conditions of approval have been modified to reflect this and state that the Project Applicant is required to obtain the approval of the owner of any heritage trees that are not located on property owned by the Project Applicant. At the Planning Commission Hearing, Condition of Approval #15 was modified to read as follows:

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City Council Appeal Response

Page 2 of 14 ends

Five Heritage-sized trees will be removed with the project, if written consent of the adjacent property owner(s) expressly authorizing removal or irreversible damage to the affected heritage tree(s) on adjacent properties APN 010-011-03 and 010-011-02 is provided by the project applicant to remove the Heritage-sized tree(s) located on the adjacent properties. In accordance with the replacement tree requirements, either one 24-inch box sized tree or three 15-gallon trees shall be paid for and planted by the project applicant for each heritage tree removed.

If such consent is not obtained, the applicant shall (1) revise the project plans to avoid irreparable damage and/or death to the heritage trees to the satisfaction of the City Arborist, or (2) provide evidence that pursuant to a court order or judicial decree, that they are entitled as a matter of law to remove encroaching roots and/or branches up to the property line. This condition is intended to ensure compliance with applicable laws governing private property and tree protection, and to prevent unauthorized removal or harm to trees located on property not owned or controlled by the applicant or City.

As shown above, this condition now provides that written consent of the property owner is required prior to removal or irreversible damage to the affected tree.

Condition of Approval #39 was modified as follows:

Prior to building permit issuance, a tree protection plan is required to be submitted for the proposed project, including the one Heritage-sized Walnut tree, one Heritage-sized Layland Cypress tree, and one Heritage-sized Incense Cedar tree to be incorporated into the project, if the adjacent property owners do not authorize the trees to be removed and the applicant revises the project plans as recommended in the Arborist Report prepared by Kurt Fouts and dated 04/30/2024.

As such, no trees that are not on Project site will be removed without the consent of the owner of such tree.

With respect to possible damage to the off site trees, an Arborist Report was prepared for the Project by Kurt Fouts on April 30, 2025 and an Addendum to that report was prepared on May 25, 2025 and is attached hereto as Exhibit A (“Arborist Report”). As outlined in the Arborist Report, since the Planning Commission Hearing, a root exploration was done at the Project site to determine possible impacts to roots associated with the trees on Appellant’s property. As stated therein, “[t]he trench was dug to discover the number, size, and location of significant roots that would need to be pruned for the new building foundation. No significant roots were found.”1 The Arborist Report further concluded that “the new building foundation will have minimal, or no effect, to the roots of the three cypresses,” which include the tree on 1 Arborist Report, p. 3.

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Appellant’s property.2 The Arborist Report further concludes that any canopy loss to the cypress trees will be within the trees’ tolerance.3
\
We also note that California law allows property owners to cut any roots or branches that encroach onto the owner’s property. “The weight of authority is that to the extent that limbs or roots extend upon an adjoining landowner's property the latter may remove them, but only to the boundary line. (1 Am.Jur. p. 537.) California follows this rule.” Bonde v. Bishop (1952) 112 Cal. App. 2d 1, 5, 245 P.2d 617, 620. Appellant argues that if “cutting the roots of the Heritage trees would destroy or harm the trees, [Project Applicant] may not do so.” (Appeal, p. 2-3). The case cited by Appellant, however, Russell v. Man (2020) 58 Cal.App.5th 530, 537, further confirms that “[o]rdinarily, when the roots of a tree on A's land grow into the land of B, B has the right to cut them.” The case goes on to distinguish that there is an exception “when cutting the roots unnecessarily kills or injures the tree.”4 As such, Project Applicant may cut the roots so long as any work of that nature does not unnecessarily kill or injure the tree. As discussed in the Arborist Study, the Project will not damage the roots of or unnecessarily injure the Heritage Tree on Appellant’s property.

Lastly, since the Planning Commission Hearing, the City has added the following two conditions of approval to the Project, which would further ensure that any off-site trees are not unnecessarily injured during the construction of the Project. • Prior to building permit issuance, the applicant shall submit a copy of a signed contract with a qualified arborist (based on the city’s list of approved consultants or as previously authorized by the Planning Department) indicating that the arborist will be on retainer to monitor the tree protection and that they will provide a follow-up letter to the Planning Department with the results of the monitoring. • Prior to finaling the building permit, a follow-up letter prepared by the Project Arborist discussing results of the mitigation measures and impacts of the demolition and construction phase to the Heritage Trees must be provided to the Planning Department and City Arborist for review.

As such, the City properly issued the tree removal permits.

B. The Project Meets the Requirements of the Infill Exemption Pursuant to CEQA Guidelines Section 15332.
a. The Project Complies with All Santa Cruz Zoning Regulations, Including the City’s Watercourse Development Permit Requirements.
2 Arborist Report, p. 5.
3 Arborist Report, p. 5.
4 Russell v. Man (2020) 58 Cal.App.5th at 537.

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This issue is identical to the issue raised to the Planning Commission. The Project is consistent with the SCMC, including the City’s Watercourse Development Permit requirements. Pursuant to Section 24.08.2150 of the SCMC, the Project will require a Watercourse Development Permit. As identified in the Project materials, the Property is located adjacent to the channelized portion of Branciforte Creek (the “Creek”), called Reach 1, which the City-Wide Creeks & Wetlands Management Plan (“Wetlands Plan”) recognizes is not where most of the Creek’s birds, animals, and aquatic species reside.5 The Project will not impact the “lower” or any other portion of the Creek, or any species residing therein, contrary to Appellant’s claims.

The Project would occur entirely outside the 30-foot riparian corridor area under the Wetlands Plan. A portion of the Project is within the 50-foot development setback under the Wetlands Plan. However, the existing building on the Property is already within the development setback and the Project will not encroach any further into the development setback than the existing building and will reduce the square footage of building area located within the development setback. In addition to the existing building on the Property, there are several other structures within the 50-foot development setback along this channelized portion of Branciforte Creek, including the commercial building directly across the creek from the Property at 600 Ocean Street and the commercial building across Ocean Street from the Property at 533 Ocean Street.

Consistent with the existing condition of these buildings, the SCMC allows for a Watercourse Variance to encroach into the 50-foot setback and here a Watercourse Variance would be required per SCMC Section 24.08.2200. A Density Bonus waiver to the Creek’s development setback is being requested in place of the Watercourse Variance. Therefore, the development is permitted with the issuance of a Watercourse Development Permit and Density Bonus waiver to the development setback from the Creek.
b. There Are No Unusual Circumstances Resulting in a Reasonable Possibility of a Significant Effect.

This issue is identical to the issue raised to the Planning Commission. CEQA Guidelines Section 15300.2(c) provides that “[a] categorical exemption shall not be used for an activity where there is a reasonable possibility that the activity will have a significant effect on the environment due to unusual circumstances.” There is a two-part test that governs the application of the unusual circumstances exception to use of a categorical exemption, set forth by the California Supreme Court in Berkeley Hillside Preservation v. City of Berkeley (2015) 60 Cal.4th 1086 (Berkeley Hillside). The exception applies if a party can establish: (1) an unusual circumstance by showing that the project has some feature that distinguishes it from others in the exempt class, such as its size or location; and (2) there is a reasonable possibility of a significant effect due to that unusual circumstance.6
The fact that there is historical contamination migrating from an off-site source (the Former Classic Cleaners located at 607-609 Soquel Avenue) to the Project site does not represent an 5 Wetlands Plan pages 3-10 through 3-11. 6 Berkeley Hillside at 1097-1099.

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unusual circumstance within the meaning of Guidelines Section 15300.2. Many infill sites have some amount of historical contamination. The court in Protect Tustin Ranch v. City of Tustin (2021) 70 Cal.App.5th 951, 962 (Protect Tustin) held that the former operations of a Goodyear service center at the project site, including the installation of tires as well as oil and other fluid changes, and plaintiff’s claims of possible contamination associated therewith did not represent “unusual circumstances.” The court noted that these features did not “distinguish the project from others that would qualify for the infill exemption, and [the plaintiff did] not cite any evidence from the record demonstrating a distinction.”7 In addition the court, citing Berkeley Hillside, indicated whether an unusual circumstance exists is a question of fact:
“Whether a particular project presents circumstances that are unusual for projects in an exempt class is an essentially factual inquiry, ‘founded ‘on the application of the factfinding tribunal's experience with the mainsprings of human conduct.’ [Citation.] Accordingly, as to this question, the agency serves as ‘the finder of fact’ [citation], and a reviewing court should apply the traditional substantial evidence standard .... [A]fter resolving all evidentiary conflicts in the agency's favor and indulging in all legitimate and reasonable inferences to uphold the agency's finding, [the court] must affirm [the agency's] finding if there is any substantial evidence, contradicted or uncontradicted, to support it.”
Berkeley Hillside also states that agencies can look to the context of the area to determine what is typical.8 Here, the context is an urbanized environment and minor historic contamination is migrating from off-site to the site. This is in no way unusual as it is very common for redevelopment sites to have some minor level of contamination.9 As such, the City may properly determine that the minor historical contamination associated with migration to the Property does not represent an unusual circumstance. The City’s determination will be reviewed with deference.

In addition, the Class 30 exemption found at Guidelines Section 15330 exempts from CEQA review “any minor cleanup actions taken to prevent, minimize, stabilize, mitigate, or eliminate the release or threat of release of a hazardous waste or substance which are small or medium removal actions costing $1 million or less.” This exemption indicates that it is the intent of the legislature that minor amounts of contamination do not represent an environmental impact. As further detailed below and in the Langan letter report dated May 1, 2025, minor historic contamination at the Project site is appropriately addressed through the removal and disposal of a maximum of 800 cubic yards of impacted soil and as a conservative measure, the installation of a vapor mitigation system under the proposed building. The cumulative, maximum cost of remediating these items is far less than $1 million. Thus, the Class 30 7 Protect Tus8n at 962. 8 Berkeley Hillside at 1119. 9 hDps://www.eli.org/brownfields-program/brownfields-faq

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exemption applies to the remediation activity.10 It is illogical to argue the clean-up of this minor contamination, with the majority of the contaminants migrating from off-site, as the basis for finding the Project is not exempt when the clean-up itself would be exempt.

As such, the contamination on the Project site cannot be considered an unusual circumstance - it is per se not unusual and is common for in-fill sites and the remediation activity itself is exempt.

Even if the minor contamination on the Property did represent an unusual circumstance, which it does not, Appellant has not provided any evidence that the minor contamination at the Project site would cause any significant effects. As indicated in the Langan Soil, Soil Vapor, And Groundwater Assessment Letter Report dated May 1, 2025 and attached hereto as Exhibit B (“Langan Report”), the impacted soil at the Property has been fully delineated to one shallow, less than 5 feet below ground surface, hot spot, that can be off hauled and disposed of at an appropriately licensed facility as non-hazardous in accordance with applicable laws and regulations. As indicated in the Langan Report , to conservatively address the off-site (Former Classic Cleaners, 607-609 Soquel Avenue) soil vapor plume, the Project Applicant has voluntarily agreed to install a chemical resistant vapor barrier membrane, of a continuous spray-applied or sheet membrane located immediately beneath the structural building slab. Additionally, below-grade utility conduits entering the building will be sealed to prevent VOC migration along the conduits from outside the building into the sub-slab space beneath the building. The proposed vapor barrier membrane materials and design will be reviewed by a professional engineer (PE) registered in the State of California. As noted above, the ground floor of the Project does not contain any residential uses and consists of primarily parking, as well as some residential amenities and a 3,394 square foot commercial space. As such, there is no threat of vapor intrusion to adversely impact future residents of the Project.

As further confirmed by the Langan Report, construction and operation of the proposed Project will not result in any exposure of future residents of the Project or neighboring community to contaminants present at the site in soil, groundwater, or soil vapor at the Project site.

Further, this off-site source of Former Classic Cleaners, 607-609 Soquel Avenue, is under oversight by the County of Santa Cruz, CASE #: RO0000389.11 As of November 2024, quarterly groundwater sampling is continuing and soil vapor extraction was recently implemented. These actions should continue to reduce any potential impacts in soil vapor from future residents of the Project site, as well as surrounding neighbors.

This minor historical contamination would not impact the Creek or special status species or plants associated therewith. As further discussed below, the Creek where it abuts the Property is within a concrete culvert that is approximately 17 feet deep/below the ground level of the Project site. With respect to impacted soil gas associated with the off-site soil vapor plume, 10 Note that mulMple exempMons can be applied to components of a project. 11 hDps://geotracker.waterboards.ca.gov/profile_report?global_id=T10000018697.

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construction of the Project does not present or complete any pathway for soil gas to reach the Creek or any of the species associated therewith. As further confirmed by the Langan Report, construction and operation of the proposed Project will not result in any exposure of the Creek to contaminants present at the site in soil, groundwater, or soil vapor at the Project site.

As discussed that the Planning Commission Hearing, the Project Applicant has entered into a voluntary clean up agreement with the Department of Toxic Substances Control (“DTSC”). DTSC will oversee the development of the Project site to ensure that nothing at the Project site represents a risk to human health or the environment, which includes future occupants of the Project, neighbors, and nearby natural resources, including the Creek. The City is in receipt of the agreement and it is a public document. The City is also in receipt of the environmental studies associated with the Project site.

With respect to possible impacts to the Creek, special status species, or the environment due to the Project’s proximity to the Creek, as identified in the Project materials, including the Biological Report, the Property is located adjacent to the channelized portion of the Creek, called Reach 1, which the Wetlands Plan recognizes is not where most of the Creek’s birds, animals, and aquatic species reside.12 In this location, the channel sides are vertical and composed of concrete, and there is no riparian vegetation present. To provide flood protection, the channel was designed to operate optimally when there is no sediment or trees.13 As noted above, the Project would occur entirely outside the 30-foot riparian corridor area under the Wetlands Plan. A portion of the Project is within the 50-foot development setback under the Wetlands Plan. However, the existing building on the Property is already within the development setback and the Project will not encroach any further into the development setback than the existing building and in fact will reduce the square footage of building area located within the development setback.

Similar to the requirements of a Watercourse Variance, the Biological Report evaluated the potential impacts of the Project on the Creek. As outlined therein, two special status wildlife species may occur in adjacent areas: central coast steelhead and Pacific lamprey are known to inhabit Branciforte Creek; however, the Biological Report found that based on the channelization of the Creek and the current design of the Project, no impacts to these species will occur. In addition, steelhead require “gravel-bottomed, fast-flowing, well-oxygenated rivers and streams” to hatch,14 which is not possible in the creek due to its concrete channelization.

The proposed Project will only redevelop the existing developed area and, as described in the Biological Report, the development area has no value as habitat for any special-status plant or wildlife species known to occur in the general region of the Project site. As detailed in the Biological Report, the Project will comply with Watercourse Development Standards 1 through 12 Wetlands Plan pages 3-10 through 3-11. 13 Id. 14 hDps://www.fisheries.noaa.gov/species/steelhead-trout.

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16 of the Wetlands Plan.15 As such, the Project’s proximity to the Creek also does not represent an unusual circumstance nor is there any potential for a significant environmental impact, nor has appellant presented any evidence of unusual circumstance or a potentially significant impact.

C. The Planning Commission’s Decision That the Project is Exempt from CEQA Pursuant to CEQA Guidelines Section 15332 Was Based on Substantial Evidence in the Record.

This issue is identical to the issue raised to the Planning Commission. There is no requirement under CEQA or the CEQA Guidelines that agencies follow any specific procedure in approving activities that are exempt from CEQA. The agency is not required to hold a hearing on the exemption nor is it required to provide an opportunity to review or comment on the exemption.16 Rather the agency’s decision must be made based on “substantial evidence that the [activity is] within the exempt category of projects’ [and] … [t]hat evidence may be found in the information submitted in connection with the project, including at any hearings that the agency chooses to hold.”17 The Planning Commission’s decision that the Project is exempt from CEQA pursuant to CEQA Guidelines Section 15332 was based on substantial evidence in the information presented to the City, including the materials submitted by Project applicant as well as publicly available information regarding the Project site.

D. The Project’s Waiver of the Watercourse Development Permit’s Required Setbacks from Branciforte Creek Would Not Have an Adverse Impact on Public Health and Safety.

This issue is identical to the issue raised to the Planning Commission. As noted above, the Project has requested a waiver of the Development Setback from the Creek. Appellant contends that such a waiver cannot be granted as it will “have a specific, adverse impact … upon health or safety” within the meaning of Government Code Section 65915(e)(1). Appellant argues that the specific, adverse impact upon health or safety results from the construction on a Project site with minor historical contamination in the vicinity of the Creek. Appellant incorrectly asserts that “Demolition and construction will disturb soil contamination that exceeds more than 200 times the levels deemed safe for residential areas by the State of California, and will release arsenic, chloroform, and PCE into the environment.” First, Appellant’s categorization of the screening levels as “levels deemed safe for residential areas by the State of California” is incorrect. As indicated in the California Regional Water Quality Control Board’s 2019 User’s Guide: Derivation and Application of Environmental Screening Levels:
15 Id., SecMon 4.5. 16 Robinson v. City & County of San Francisco (2012) 208 Cal.App.4th 950, 963. 17 San Lorenzo Valley Community Advocates for Responsible Educ. v San Lorenzo Valley Unified Sch. Dist. (2006) 139 CA4th 1356, 1386.

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The presence of a chemical at concentrations exceeding an ESL does not necessarily indicate adverse effects on human health or the environment, rather that additional evaluation is warranted.

Second, the construction will not “will release arsenic, chloroform, and PCE into the environment.” As indicated in the Langan Report, impacted soil at the Property can be off hauled and disposed of at an appropriately licensed facility as non-hazardous in accordance with applicable laws and regulations. As further noted in the Langan Report, construction and operation of the proposed Project will not result in any exposure of the Creek to contaminants present at the site in soil, groundwater, or soil vapor at the Project site. As discussed above, construction of the Project does not present or complete a pathway for soil gas to impact the Creek or any of the species associated therewith. The Density Bonus waiver of the development setback from the Creek will not result in a specific adverse impact upon health or safety within the meaning of Government Code Section 65915(e)(1).

E. The Project Qualifies for Elimination of Parking Requirements Pursuant to AB 2097 Because It Is Within 1/2 Mile of a Transit Stop.

AB 2097 added 65863.2 to the Government Code, which provides that “[a] public agency shall not impose or enforce any minimum automobile parking requirement on a residential, commercial, or other development project if the project is located within one-half mile of public transit.” Subsection (e)(5) defines “public transit” as “a major transit stop as defined in Section 21155 of the Public Resources Code.” Section 21155 of the Public Resources Code defines “major transit stop” “as defined in Section 21064.3, except that, for purposes of this section, it also includes major transit stops that are included in the applicable regional transportation plan.” Lastly, Section 21064.3 of the Public Resources Code defines “major transit stop” as follows:
“Major transit stop” means a site containing any of the following:
(a) An existing rail or bus rapid transit station.
(b) A ferry terminal served by either a bus or rail transit service. (c) The intersection of two or more major bus routes with a frequency of service interval of 20 minutes or less during the morning and afternoon peak commute periods.

As shown on the City’s GIS below, the Project site is within ½ mile of two Major Transit Stops, which, although unlabeled are stop 2667: Front & Soquel Ave and stop 2754: River Street & Soquel Ave.18
18 hDps://vwgisportal.cityofsantacruz.com/public/.

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In addition, the Project site is within ½ mile of stop 1713: River/River Front Garage, which meets the definition of “major transit stop” set forth in Section 21064.3 of the Public Resources Code set forth above. Stop 1713 is identified as a Major Stop on the Santa Cruz County GIS, which further identifies the Project site as within a Transit Priority Area, as shown below.

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Appellant now contests the method of measuring the distances to transit. At the Planning Commission Hearing, this distance was stated as measured “as the crow flies.” The phrase “as the crow flies” means in a straight line.19 Appellant indicates in the Appeal that the City “provide[s] no legal basis for this assertion” and that neither the City’s Municipal Code nor Government Code Section 65863.2, which implements AB 2097 “indicate that this distance is calculated ‘as the crow flies.’”20 The California Department of Housing and Community Development (“HCD”) published a technical advisory on the Implementation of AB 2097 in January 2025 (“HCD Advisory”).
21 The HCD Advisory states “The distance to a major transit stop is measured in a straight line from the nearest edge of the parcel containing the proposed project to any point on the parcel or parcels that make up the property upon which a major transit stop is located.”22 As such, the City correctly measured the distance to the multiple major transit stops within ½ mile of the Project site and correctly applied Section 65863.2 of the Government Code.
19 hDps://dicMonary.cambridge.org/us/dicMonary/english/as-the-crow-flies. 20 Appeal, p. 10. 21 hDps://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/ab-2097-ta.pdf. 22 HCD Advisory, p. 6.

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F. The Project Applicant is Not Required to Prove that Provision of Metro Bus Passes Would Physically Preclude Construction of the Project.

Appellant newly and incorrectly asserts that the Project Applicant “requested a waiver of the requirement that it provide Metro Bus passes to all project residents” and did not prove that this waiver “would physically preclude the construction” of the Project.23 While Appellant is correct that development standards which would physically preclude construction of the Project are subject to waivers under the Density Bonus Law, the Density Bonus Law also affords developers concessions in exchange for the provision of affordable units, which include, among others, “regulatory incentives or concessions proposed by the developer or the city, county, or city and county that result in identifiable and actual cost reductions to provide for affordable housing costs.”24 As identified in the Project materials, the Project is entitled to three (3) concessions in connection with the 39 affordable units provided by the Project pursuant to Government Code Section 65915(d)(2). As noted in the Planning Commission Appeal materials, a requirement to provide Metro Bus passes to all Project residents was previously included as Condition of Approval No. 68. The Project Applicant used one of the three concessions granted to the Project to waive this requirement. A city may deny a concession if the concession (1) would not result in identifiable and actual cost reductions; (2) would have a specific adverse effect on public health or safety or on any real property that is listed in the California Register of Historical Resources; or (3) would be contrary to state or federal law.25 Due to the cost of the provision of Metro Bus passes to all Project residents, this concession results in identifiable and actual cost reductions to the Project of approximately $250,000.26 The concession does not result in any adverse effects on the public health or safety or any real property listed in the California Register of Historical Resources nor is it contrary to state or federal law. As such, the City properly granted this concession.

None of the issues presented in the Appeal present a legal or factual basis as to why the proposed Project is not categorically exempt. Substantial evidence in the Project record, including materials submitted by the Project Applicant as well as publicly available information, confirms that the Project is categorically exempt from CEQA review. We are happy to discuss any issues or concerns the City has. We ask City Council find the project exempt and approve the Project.

Very truly yours,

MONCHAMP MELDRUM LLP
23 Appeal, p. 11. 24 Government Code § 65915(k)(3). 25 Government Code § 65915(d)(1). 26 Note that a discussion of this concession can be found in the Planning Commission Staff Report as well at pages 17 and 31.

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Exhibit A
Arborist Report

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Addendum to:

ARBORIST REPORTTree Survey & Preliminary Impact Assessment 530, 542 & 548 Ocean Street
Santa Cruz, CA
APN:010-011-16, 31, 30
April 30, 2024

Addendum Date 5/25/2025

Prepared for:

Riaz Capital
2244 East 11th Street
Oakland, CA
Prepared by:

ISA Certified Arborist WE0681A
ISA Tree Risk Assessment Qualification (TRAQ)

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Addendum to Arborist Report 5/25/2025
530, 542 & 548, Ocean St., Santa Cruz Page 1
Background
This addendum contains revisions to the preliminary construction impact assessment on trees surveyed in the arborist report dated 4/30/2024. Since that report, the proposed building footprint has been moved from one foot away from the property line, to three feet from the property line. On 5/15/2025, root exploration work was performed near the property line to determine the number, size, and location of roots from trees growing on the adjacent property, and close to the property line. Based on the root exploration information, I have identified changes to the anticipated root loss impacts of some trees. Additionally, the building footprint has been revised, and I have identified changes to the anticipated canopy loss impacts to some trees based on the revised footprint.

Because the impacts to some trees have been revised, the tree disposition recommendations have also been revised, and are discussed in the text below.

Summary
Based on the root exploration information, and revised building footprint location, the anticipated construction impacts to three Leland cypress trees will be reduced from high to moderate. In my report dated 4/30/2025, the trees were recommended for removal due to high construction impacts. Because the anticipated impacts to the three trees is now reduced to moderate, the trees can be retained. The three Leyland cypress trees include trees, T9, T10 and T11.

Table T1, shown below, has been updated. The Tree Assessment Chart spreadsheet, and Sheet T1, Tree Location Map, (attached), were also updated to reflect the revised anticipated construction impacts, and tree disposition.

Data Summary
Table 1 – All Surveyed Trees
General
Total Trees Inventoried Count
Total 13
Species 7
Regulated Trees
Heritage Trees
All trees > 14” trunk diameter 6
Tree Disposition Categories – All Trees
R.I. – Remove due to construction impacts 9
R.C. – Remove due to condition (poor condition) 0
R.T., I.M. - Retain tree. Preservable, low or moderate impacts that can be mitigated. 4

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Root Exploration Description
An exploratory trench was dug to a depth of 24 inches, and 3 feet from the property line. The trench is opposite from three Leyland cypress trees, growing on the adjacent property, (Image #1).

Image #1 – The three Leyland cypress trees growing on the adjacent property. The soil pile from the hand digging excavation work can be seen in this image.

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The trench was dug to discover the number, size, and location of significant roots that would need to be pruned for the new building foundation. No significant roots were found, (Image #2).

Image #2 – No significant roots from the 3 cypress trees were found. The 1/4” to 1/2” roots seen in this image are likely from the xyloma shrubs that were removed during the hand digging process.

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At one end of the trench the hand digging went down to the bottom of the block wall footing.

This was done to determine the depth of the footing. The footing depth was 3 feet, (Image #3).

Image #3 – A tape measure was used to determine the depth of the footing.

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Root Exploration Findings & Impact Assessment to Cypress Trees On 5/20/2025, I met with the City of Santa Cruz Urban Forester, Leslie Keedy, at the proposed project site at 530 Ocean Street , Santa Cruz. The purpose of our meeting was to document the root exploration information, and discuss the anticipated root loss and canopy loss impacts to the three Leyland cypress trees, the Incense cedar, and the walnut tree. All five of these trees are growing on properties adjacent to the proposed project. We also discussed the mitigation, (targeted clearance pruning), necessary to create space for the building construction.

Anticipated Root Loss to the Three Cypress Trees
Because the block wall footing extends to a depth of 3 feet, and since most roots of any tree are found in the upper 18” of the soil profile, I do not anticipate discovery of significant roots, (root 2” in diameter or >), when excavation occurs for the proposed building foundation. Therefore, the new building foundation will have minimal, or no effect, to the roots of the three cypresses.

Anticipated Canopy Loss to the Three Cypress Trees
The three cypress trees will require targeted clearance pruning to allow room for the building construction. Because the building footprint has been moved back from the previously proposed footprint, the canopy loss impacts to the trees will be reduced. I estimate between 25 -30% of the cypress trees canopy will need to be removed, and canopy losses will be within the trees tolerance.

Targeted clearance pruning of the three cypress trees, T9, T10 and T11, to achieve clearance for building construction will be necessary. The pruning shall be performed under direction of the project arborist. All pruning cuts shall be made to a live side branch. If no side branch is available, the cut shall be made at the parent stem/ or trunk. These cuts will require permission from the owner to allow trespass to make cuts at the trunk. If the owner of the cypress trees will not allow trespass to make a cut following proper arboricultural practices, the tree pruner shall make a stub cut at the property line.

It should be noted that stub cuts do not follow industry standards for proper pruning. However, stub cuts will not significantly harm the tree, and I noted many existing stub cuts present on the tree from past practices, (Images #4 & #5, page 6).

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Image #4 – Tree T9, cypress. Note multiple stub cuts.

Image #5 – Trees T9, T10 and T11, cypress. Note multiple stub cuts on all trees.

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Observations & Discussion
During my site visit, I noted that the three cypress trees have multiple symtoms of cypress canker disease including, flagging, (scattered tip dieback), browning of needle bundles, and some branch bleeding, (Images #6 & #7).

Image #6 – Trees T9 and T10. Note flagging, (tip dieback), and browning needle bundles, circled.

Image #7 – Tree T10, cypress. Note tip dieback and browning needle bundles, (circled).

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Cypress canker is a disease common to this region, and these trees have a minor infection level at the time of this report. It should be noted that any pruning by the applicant is not the cause of this preexisting condition.

Construction Impact Assessment to Incense Cedar and Walnut Since the building footprint location has been revised, I reviewed the anticipated construction impacts to tree T12 Incense cedar and T13, walnut with Ms. Keedy.

The impacts to the Incense cedar, (high), and the walnut, (moderate), have not changed based on the new footprint.

We agreed that the cedar will suffer significant canopy loss beyond the trees tolerance, and it should be removed. The walnut will have some canopy loss, and possibly some root loss. Both losses will be within the walnut trees tolerance, and it can be retained.

Respectfully submitted,
Kurt Fouts ISA Certified Arborist WE0681A
ISA Tree Risk Assessment Qualification (TRAQ)
Attachments:
 Revised Tree Assessment Chart
 Revised Sheet T1, Tree Location Map
 Tree Protection Specifications
 Arborist Report Dated 4/30/2024

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Tree Protection Specifications
Whenever construction work includes soil disturbance near protected trees, the Project Arborist shall be contacted to supervise work. The arborist shall be given 48 hours’ notice for site visits. The Projects Arborist shall document work completed, tree condition, and address any areas of concern.

Demolition Phase:

1. Tree Protection Fencing - Install Tree Protection Fencing, in location indicated on Sheet T1, Tree Location Map after demolition of building adjacent to tree T13, walnut. If block wall adjacent to trees T9, T10 and T11, Leyland cypress is demolished, install tree protection fencing, , in location indicated on Sheet T1, Tree Location Map after demolition of wall. .

2. Clearance Pruning - Targeted clearance pruning of the three cypress trees, T9, T10 and T11, to achieve clearance for building construction will be necessary. The pruning shall be performed under direction of the project arborist. All pruning cuts shall be made to a live side branch. If no side branch is available, the cut shall be made at the parent stem/ or trunk. If the owner of the cypress trees will not allow trespass to make a cut following proper arboricultural practices, the tree pruner shall make a stub cut at the property line.

All pruning shall be performed using industry standards of workmanship as established in the Best Management Practices of the International Society of Arboriculture (ISA), and the American National Standards Institute, Safety Requirements in Arboriculture Operations ANSI Z133-2017. Contractor licensing and insurance coverage shall be verified. Any pruning necessary should be assessed by the contractor and project arborist prior to the start of construction.

Construction Phase:

1. Building Foundation – Excavation for the building foundation opposite Leyland cypress trees T9, T10 and T11, and walnut T13, shall be supervised by the Project Arborist. If any significant root, (roots 2” in diameter or greater), are found, they shall be cleanly pruned with a Sawzall or similar tool, under direction of the arborist. Pruned root ends shall be kept covered with moistened burlap until the exaction is backfilled and the roots are covered with soil.

43.583

ARBORIST REPORTTree Survey &
Preliminary Impact Analysis

530, 542 & 548 Ocean Street
Santa Cruz, CA
APN:010-011-16, 31, 30
April 30, 2024
Prepared for:

Riaz Capital
2244 East 11th Street
Oakland, CA
Prepared by:

ISA Certified Arborist WE0681A
ISA Tree Risk Assessment Qualification (TRAQ)

43.584

Table of Contents SUMMARY.................................................................................................................................. 1 Data Summary………………………………………………………………………………………...……….1
Background .................................................................................................................... 2 Assignment .................................................................................................................... 2 Limits of the Assignment................................................................................................ 2 Purpose and use of the report ....................................................................................... 2 Resources...................................................................................................................... 3 OBSERVATIONS....................................................................................................................4-7 DISCUSSION ............................................................................................................................. 8 Species List.................................................................................................................... 8 Tree Evaluation and Recording Methods ...................................................................... 8 Condition Rating ............................................................................................................ 9 Suitability for Preservation ............................................................................................. 9 Tree Protection Zone ...................................................................................................10 Critical Root Zone ........................................................................................................10 Root Disturbance Distance…………………………………………………………………11
Impacts to Heritage Trees ..…………………….....………………………………………12-15 Tree Removal and Replacement……………………………………………………….….16
Certificate of Performance…………………………………………...…………………………………..17 CONCLUSION …………………………….……………………………………………………………….……………….18 RECOMMENDATIONS…………………………………………………………………………………………………..18

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Attachments: Appendix A - H
Appendix A – Tree Assessment Chart
Appendix B – Criteria for Tree Assessment Chart
Appendix C - Sheet T1 - Tree Location Map
Appendix D- Glossary of Terms
Appendix E - City of Santa Cruz, Encroachment & Tree Permit Fees Appendix F – Bibliography
Appendix G - Tree Protection Guidelines & Restrictions
 Protecting Trees During Construction
 Project Arborist Duties & Inspection Schedule
 Tree Protection Fencing
 Tree Protection Signs
 Monitoring
 Root Pruning
 Tree Work Standards & Qualifications
Appendix H - Assumptions & Limiting Conditions

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SUMMARY
This report provides the following information:

1. A summary of the health and structural condition of 13 trees.

2. A preliminary evaluation of anticipated construction impacts to the trees.

3. Recommendations for retention or removal of assessed trees based on their condition, construction impacts, and future uses.
 A six story multi-family apartment building is proposed at 530, 542 and 548 Ocean Street, Santa Cruz. I surveyed six Heritage trees on the property, or with canopies that overhang the subject property. A Heritage tree is protected as defined by the City of Santa Cruz Ordinance.
 The Heritage trees are in good or fair condition and are suitable for incorporation into the project.
 One Heritage tree will have moderate construction impacts, can be incorporated into the project, and will require mitigation methods to reduce construction impacts.  Five Heritage trees are in direct conflict with the project and their removal will be necessary to accommodate construction of the building.
 This report assesses anticipated impacts to affected trees and is based on a preliminary site plan. Depending on revisions to the preliminary site plan, impacts to trees may change and will require reassessment. Once the final plan set is completed, a Tree Protection Plan will be required and shall be included with the final plan set.
 The Tree Assessment Chart, Appendix A is the condensed reference guide to inform all tree management decisions for the trees evaluated.

Data Summary
Table 1 – All Surveyed Trees
General
Total Trees Inventoried Count
Total 13
Species 7
Regulated Trees
Heritage Trees
All trees > 14” trunk diameter 6
Tree Disposition Categories – All Trees
R.I. – Remove due to construction impacts 12
R.C. – Remove due to condition (poor condition) 0
R.T., I.M. - Retain tree. Preservable, low or moderate impacts that can be mitigated. 1

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Background
A preliminary plan set had been completed for a six story multi-family apartment building at 530, 542 and 548 Ocean Street, Santa Cruz. Riaz Capital requested my services to assess the condition of thirteen trees within or near the project limits, and the construction impacts that may affect them. Further, to provide a report with my findings, and recommendations to meet the City of Santa Cruz requirements.

Assignment
Provide an arborist report that includes an assessment of the trees within the project area. The assessment is to include the species, size (trunk diameter, height and canopy spread), condition (health and structure), and suitability for preservation ratings. Review preliminary development plans, assess potential impacts to trees, and provide recommendations for retention or removal.

To complete this assignment, the following services were performed:
 Tree Survey, Assessment & Recommendations: Inventory, evaluate and make recommendations for subject trees.
 Plan Review: Reviewed provided plans including Preapplication Plan Set, dated 2/28/2024, by Workbench, Architects.
 Impact Assessment: Recommendations for retention or removal of assessed trees based on their condition, construction impacts, and future uses.

Limits of the Assignment
The information contained in this report covers only those items that were examined and reflects the condition of those items at the time of inspection April 22, 2024.

The inspection is limited to visual examination of accessible items without climbing, dissection, excavation, probing, or coring. There is no warranty or guarantee, expressed or implied, that problems or deficiencies of the trees in question may not arise in the future.

Purpose and use of the report
The report is intended to provide a condition evaluation and management recommendations for the trees inventoried. This report is to be used by the applicant, their agents, and the City of Santa Cruz as a reference for existing tree conditions, and to help satisfy City of Santa Cruz planning requirements.

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Resources
All information within this report is based on site plans as of the date of this report. Resources are as follows:
 Preapplication Plan Set, dated 2/28/2024, by Workbench, Architects.  Site Visit, Tree Inventory & Condition Evaluation, 530, 542 and 548 Ocean Street, Santa Cruz, on 4/22/2024.
 City of Santa Cruz Municipal Code – Chapter 9.56 Preservation of Heritage Trees (applicable sections).

City of Santa Cruz

9.56.040 HERITAGE TREE AND HERITAGE SHRUB DESIGNATION.

Any tree, grove of trees, shrub or group of shrubs, growing on public or private property within the city limits of the city of Santa Cruz which meet(s) the following criteria shall have the “heritage” designation:
(a) Any tree which has a trunk with a circumference of forty-four inches (approximately fourteen inches in diameter or more), measured at fifty-four inches above existing grade; (b) Any tree, grove of trees, shrub or group of shrubs which have historical significance, including but not limited to those which were/are:
(1) Planted as a commemorative;
(2) Planted during a particularly significant historical era; or (3) Marking the spot of an historical event.
(c) Any tree, grove of trees, shrub or group of shrubs which have horticultural significance, including but not limited to those which are:
(1) Unusually beautiful or distinctive;
(2) Old (determined by comparing the age of the tree or shrub in question with other trees or shrubs of its species within the city);
(3) Distinctive specimen in size or structure for its species (determined by comparing the tree or shrub to average trees and shrubs of its species within the city); (4) A rare or unusual species for the Santa Cruz area (to be determined by the number of similar trees of the same species within the city);
(5) Providing a valuable habitat; or
(6) Identified by the city council as having significant arboricultural value to the citizens of the city

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OBSERVATIONS
The project is located in a commercial area on Ocean Street between Soquel Avenue and Dakota Avenue in Santa Cruz. Branciforte Creek runs to the North of the project boundary. The proposed project area contains three parcels and four exisiting builidngs, (Image #1).

Image #1 – Project is located on Ocean Street, Santa Cruz. Approximate project boundaries are outlined in red.

I surveyed thirteen trees 6-inches or greater in diameter. Six trees surveyed are defined as Heritage trees according to the City of Santa Cruz ordinance. A Heritage Tree includes any species 14 inches in diameter or larger, measured at 4.5 feet above grade.

Three of the Heritage trees are palm trees growing in a landscape planter fronting Ocean Street.

The other three Heritage trees grow on properties adjacent to the project, have canopies overhanging the subject property, and include a cypress, a cedar and a walnut.

T3 T2 T1

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Three Heritage palm trees grow in a landscape planter fronting Ocean Street, (Image #2).

Image #2 – Heritage trees T3, queen palm and T5 & T6 fan palm. The other palm trees in the image have trunk diameters below protected size.

Tree T3, a 14.5” diameter semi-mature queen palm grows along the Ocean Street frontage. The palm has a full, dense canopy. The trunk is straight and the palm is stable. Overall the palm is in good condition.

Tree T5, a 19” fan palm and T6, a 22” fan palm grow opposite each other at the entrance walkway for 542 Ocean Street. The trees are of similar size, have dense full canopies, and some dead fronds in the lower canopy. Both palms are in good condition.

Three other queen palms in image #2 are below protected size. The three queen palms are in fair or good condition.

Two trees that are below protected size grow in landscape planters between 542 and 548 Ocean Street. The species includes one evergreen pear and one privet. The two trees are in fair condtion.

T3
T5
T6

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Five trees on the adjacent properties have canopies that overhang the project limits. (Image #3) Image #3 – Heritage trees T9, cypress, T12, cedar and T13, walnut grow on two adjacent lots and have canopies that overhang the subject property.

Three of the five trees are Heritage trees. They grow near the east property line, behind the existing businesses and are on adjacent properties. The three trees include T9, cypress, T12, incense cedar and T13, walnut.

Tree T9, a 16” cypress grows in a row with two other cypress. Most of the lower limbs on the bottom half of the tree have been removed. Canopy density in the upper half of the tree is normal. Some limbs grow beyond the canopy outline and are over extended.

Tree T9 and the other two cypress were most likely planted for screening purposes. Their branches intermingle so that the effect is a single canopy. Overall, the three trees are in fair condition.

T9
T12
T13
T11 T10

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Image #4 – Heritage trees T12, cypress, and T13 walnut. Note trunk lean towards subject property of tree T12, cedar.

Tree T12 is a mature 24” Incense cedar. The cedar has a 10 – 15 degree trunk lean towards the subject property, (Image #4). The tree grows in competition for sunlight and space with the adjacent walnut. Because of this competition, most of the brancing structure is on one side of the tree. This structure creates an unbalanaced canopy with a weight bias towards the subject property. The canopy density and color is normal for the species. Overall the trees health is fair with the structure rated fair to poor due to the one sided branching structure, unbalanced canopy, and trunk lean.

Tree T13 is a mature, 30” walnut. The canopy color and density is normal for the species. The tree was topped at about 35’ above grade and branches have resprouted at the locations the tree was topped. Some of these resprouted branches may have weak attachments and could be supseptible to breakage as they incease in length. Overall, the tree is in fair condition.

T12
T13

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DISCUSSION
Species List
Table 2 – Heritage Trees

HERITAGE TREES
Common Name Botanical Name Count
queen palm (Syagrus romanzoffiana) 1
fan palm (Washingtonia spp.) 2
Leyland cypress (x Hesperotropis leylandii) 1
incense cedar (Calocedrus decurrens) 1
walnut (Julgans spp.) 1
Total Heritage Tree Count 6
Table 3 – All Trees Inventoried

ALL TREES
7 species – A complete list can be found in Appendix A – Tree Assessment Chart Total Tree Count 13
Tree Evaluation and Recording Methods
Site evaluations were made on 3/27/2024. The inventory included all trees on the property or on adjacent properties with canopies overhanging the project limits. The health and structural condition of each tree was assessed and recorded. Based on the trees’ health and structural condition, each tree’s suitability for preservation was rated and recorded.

Appendix A - Tree Assessment Chart contains the tree survey data. Appendix B contains criteria used to assess and rate trees. To correlate the data in the Tree Assessment Chart to the tree’s location on the site, refer to Appendix C - Sheet T1- Tree Location Map.

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Condition Rating- Heritage Trees
A tree’s condition is determined by an assessing both the health and structure, then combining the two factors to reach a condition rating. The tree’s condition is rated as poor, fair, or good.

The quantity of trees assigned for each category (good, fair, or poor), is indicated below:

Tree Condition Rating
 Good - 3
 Fair - 3
 Poor - 0
Suitability for Preservation- Heritage Trees
A tree’s suitability for preservation is determined based on its health, structure, age, species characteristics and longevity using a scale of good, fair, or poor. The quantity of trees assigned to each category (good, fair, or poor), is listed below.

Suitability Rating
 Good - 3
 Fair – 3
 Poor - 0

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Tree Protection Zone
The tree protection zone (TPZ) is a defined area (radius from trunk), within which certain activities are prohibited or restricted to minimize potential injury to designated trees during construction.

The size of the optimal TPZ can be determined by a formula based on 1) trunk diameter 2) species tolerance to construction impacts, and 3) tree age (Matheny, N. and Clark, J 1998). In some instances, tree drip line is used as the TPZ. Development constraints can also influence the final size of the tree protection zone.

Fencing is installed to delineate the (TPZ), and to protect tree roots, trunk, and scaffold branches from construction equipment. The fenced protection area may be smaller than the optimal or designated TPZ area in some circumstances. Tree protection may also involve the armoring of the tree trunk and/or scaffold limbs with barriers to prevent mechanical damage from construction equipment. See Tree Protection Guidelines & Restrictions – Appendix E.

Once the TPZ is delineated and fenced (prior to any site work, equipment and materials move in), construction activities are only to be permitted within the TPZ if allowed for and specified by the project arborist.

Where tree protection fencing cannot be used, or as an additional protection from heavy equipment, tree wrap may be used. Wooden slats at least one inch thick are to be bound securely, edge to edge, around the trunk. A single layer or more of orange plastic construction fencing is to be wrapped and secured around the outside of the wooden slats. Major scaffold limbs may require protection as determined by the City arborist or Project arborist. Straw wattle may also be used as a trunk wrap and secured with orange plastic fencing.

Data has been entered in the Tree Assessment Chart – Appendix A, which indicates the optimal Tree Protection Zone for each tree.

Additional general tree protection guidelines are included in Tree Protection Guidelines & Restrictions – Appendix G.

Critical Root Zone
The CRZ is the biological limit of a tree’s capacity to recover from root loss. It is “the area of soil around a tree where the minimum number of roots that are biologically essential to the structural stability and health of the tree are located. There are no universally accepted methods to calculate the CRZ.” (Clark, Metheny, Smiley, et al, The Tree Protection Zone & the Critical Root Zone, 12/2021). The methods utilized to determine the Critical Root Zone are varied and can be based on professional guidelines and/or industry standards. Criteria such as trunk diameter, tree age and vigor, species tolerance, tree architecture and existing site constraints are commonly used criteria.

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Critical Root Zone, Continued:

Using this information, the arborist can find the distance from the trunk that should be protected per unit of trunk diameter. The CRZ does not always represent a radius around the tree. When necessary, the area can be offset or shaped in a manner that accepts tree canopy constraints or existing conditions.

For purposes of this report the CRZ is the minimum tolerable distance between the trunk, and excavation that requires root cutting. I have estimated it to be five times the trunk Diameter at Breast Height, (DBH is 4.5’ above grade). For example, if a tree has a one-foot trunk diameter, the CRZ extends to five feet from the trunk.

If encroachment into the CRZ or TPZ is required to retain the tree during development, the arborist must provide alternative construction methods or preconstruction treatments to reduce impacts.

Root Disturbance Distance
No one can estimate and predict with absolute certainty what distance from a tree, a soil disturbance such as excavation for construction should be, to ensure it will not significantly affect tree stability or health. Or to what degree, (low, moderate or high), a tree might be impacted. There are simply too many variables involved that we cannot see or anticipate.

However, three times the D.B.H. (diameter at breast height), is a widely accepted minimum used in the industry for root disturbance, on one side of the trunk, and is supported by several research studies including (Smiley, Fraedich & Hendrickson 2002, Bartlett Tree Research Laboratories). This distance is often used during the design and planning phases of a project in order to estimate root loss due to construction activities. This distance is a guideline only and should be increased for trees with significant leans, decay or other structural problems.

The ISA, International Society of Arboriculture- Root Management (2017) publication recommends, “cutting roots at a distance greater than six times the trunk diameter (DBH) minimizes the likelihood of affecting both health and stability. This recommendation is given further direction by the companion publication, A.N.S.I. (American National Standard) A300 (Part 8)- 2013 Root Management, when roots are cut in a non-selective manner, i.e. in a straight line on one side of a tree. It says, if the cutting is “within six times the trunk diameter (DBH), mitigation shall be recommended”. Further, A.N.S.I. recommends the “minimum distance from the trunk for root cutting should be adjusted according to trunk diameter, species tolerance to root loss, tree age, health and site condition”.

In general, root cutting that occurs at a distance less than ten times the diameter of a tree should be undertaken by hand digging and hand (or Sawzall), root pruning. These methods help mitigate root loss impacts.

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Construction Impacts to Heritage Trees
All Heritage trees within the project limits, including palm trees T3, queen palm, and T5 & T6, fan palm, will be in the building footprint and their removal will be necessary to accommodate the project.

The remaining Heritage trees surveyed grow on adjacent residential properties that front May Avenue. This includes tree T9 cypress, T11 incense cedar and T12, walnut. Construction impacts will affect both root loss and canopy loss for these trees. Impacts to the cypress and cedar will be high and impacts to the walnut will be moderate.

The proposed ground level setback is 1-foot 5 inches from the property line, and the adjacent lots containing Heritage trees T9, T11 & T12. Because the setback is 1-foot 5 inches from the property line, when excavation for the building foundation occurs, soil will be excavated at the property line.

Tree T9, a 16” cypress grows on the adjacent lot less than one foot from the property line, (Image #5). Excavation for the new building foundation will occur within the critical root zone of the tree, 1’ X 12” ÷ 16” trunk diameter = .75 X the trunk diameter. This linear cut across the dripline of one side of the tree exceeds the root loss tolerances for the cypress, and impacts would be high.

Several anchoring roots which stabilize the tree would be cut, increasing the risk of tree failure.

Image #5 – Heritage trees T9, T12 & T13, and distance to property line. Also shown is approximate canopy outline (green outline), that overhangs building envelope.

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Construction Impacts to Heritage Trees, Continued:

Image #6 – Cypress trees T9, T10 & T11, and extent of canopy overhang on subject property.

The canopy outline of cypress tree T9 overhangs the project limits by an average of 12-feet, (Image #6), and I estimate approximately 35% to 40% of the trees live canopy would need to be pruned for new building clearance. Because of these impacts, I recommend removal of this tree.

To retain this tree, excavation across the tree dripline should not occur closer than 4 feet. At 4 feet, root losses, with mitigation, would be within the trees tolerance. At 4-feet I estimate 25-35% of the trees canopy would need to be pruned, and the cypress could tolerate this level of pruning. Cypress trees T10 and T11 are below protected size, but since they are on adjacent property and not owned by the applicant, it should be noted that impacts for these two trees would be equivalent to those discussed for cypress tree, T9.

Tree T12, a mature, 24” incense cedar grows on the adjacent lot approximately 2.5 feet from the property line, (Image #5). Excavation for the new building foundation will occur within the critical root zone of the tree, 2.5’ X 12” ÷ 24” trunk diameter = 1.25 X the trunk diameter. This linear cut across the dripline of one side of the tree exceeds the root loss tolerances for the cedar, and impacts would be high. Several anchoring roots which stabilize the tree would be cut, increasing the risk of tree failure. The cedar has a 10 - 15-degree trunk lean which further compromises it’s stability if anchoring roots are cut close to the trunk.

T11 T10 T9

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Construction Impacts to Heritage Trees, Continued:

Image #7 – Trees T12, incense cedar, and T13, walnut, showing canopy overhang above subject property. An approximate amount of clearance pruning, (canopy removal cedar, red outline, and walnut, blue outline), that would be necessary to accommodate construction of the building is shown Because the cedar has a trunk lean towards the subject property, most of its branching structure over hangs the proposed building envelope, (Image #7). I estimate approximately 70 - 80% of the trees live canopy would need to be pruned for new building clearance. This species does not resprout on limbs that are stub cut. Since all growth is at the edges of the canopy on this tree, all clearance pruning cuts would leave stubs, and it is unlikely there would be any new regrowth after pruning. This amount of canopy loss would likely cause signinfcant decline, or tree mortality, as most of the trees energy reserves would be lost. Because of these impacts, I recommend removal of this tree.

For root loss impacts to be within tree T12 cedars tolerance, the building foundation would need to be a minimum of 6-feet from the tree. However, at 6-feet canopy losses would exceed the trees tolerance. Canopy loss is the limiting factor when estimating construction impacts for this tree, and it is difficult to estimate the minimum distance required between the cedar and the building. To retain this tree, I would estimate a range of 8-feet to 12-feet as the minimum distance between the cedar trunk and the building envelope.

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Impact Rating
 Low - 0
 Moderate – 1
 High - 5
Mitigation Measures for Retained Trees
The trees retained on this project will require some or all of the following methods to protect them from the impacts described above and to minimize root loss during the construction phases.
 Tree Protection Fencing
 Hand trenching.
 Supervised root pruning.

Applicant Requirements
1) After revisions are made to the preliminary plan set, A Tree Protection Plan will be required and shall be included with the final plan set. 2) A final inspection of the completed project by the Project Arborist is highly recommended. The inspection shall occur prior to removal of tree protection fencing and after all replacement trees have been installed.

Note: Any tree on site protected by the City Code will require replacement if it is damaged beyond repair as a result of construction activities.

Construction Impacts to Heritage Trees, Continued:

Tree T13 a, a mature, 30” walnut grows on the adjacent lot approximately 7.5 feet from the property line, (Image #5). Excavation for the new building foundation will occur within the critical root zone of the tree: 7.5’ X 12” ÷ 30” trunk diameter = 3 X the trunk diameter. With mitigation the walnut would suffer moderate root loss which it can tolerate, and the tree will need tree protection treatments to reduce root loss impacts. I estimate 15 - 20% of the trees live canopy would need to be pruned for new building clearance. This amount of canopy loss is within the trees tolerance.

Impact Level – Heritage Trees
Impact level rates the degree a tree may be impacted by construction ac tivity and is primarily determined by how close the cons truction procedures occur to the tree. Construction impacts are rated as low, moderate, and high. The quantity of trees assigned for each category (low, moderate, high), is indicated below:

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Tree Removal- Heritage Trees
Table 3 – Tree Disposition Categories – Heritage Trees
Tree Disposition Categories – Heritage Trees
R.I. – Remove due to construction impacts 5
R.C. – Remove due to condition (poor condition) 0
R.D. - Remove due to damage to structure 0
R.T., I.M. - Retain tree. Preservable, low or moderate impacts that can be mitigated.
1 Heritage Tree Removal and Replacement Trees
This report is a preliminary evaluation of construction impacts to trees. The final disposition of the Heritage trees will be determined after planning department review. If the tree removal recommendations in this report are approved, five Heritage trees will be removed. The trees recommended for removal include trees, T3 queen palm, T5 and T6, fan palm, T9 Leland cypress and T12, incense cedar. The trees most closely meet City of Santa Cruz Criterion 3:
“A Construction project design cannot be altered to accommodate existing heritage trees or shrubs”.

A Tree Permit Application will be required and if approved the applicant must fulfill a mitigation requirement:

Tree Replanting Requirement for each tree permitted for removal:

A) Replanting three (3) fifteen gallon (15 gallon), or
B) one twenty-four-inch (24”) box specimen tree
Applicants may elect to place a refundable $250.00 bond, (per tree), with the Parks and Recreation Department and replant their own tree(s); OR • Applicants may elect to pay an in-lieu fee to the tree trust fund of $1,859 per tree for off-site mitigation. (Contributions to the Tree Trust Fund are used to purchase street trees, trees for projects, etc.)
• If the $250.00 refundable bond is placed and the tree(s) are replanted, permittee must contact the City Urban Forester, 831-420-5246 after 3 months of establishment to have the $250.00 bond returned. Once the permit is issued there is a 10-day appeal period as required by ordinance before the permit becomes effective.
• If no appeal is filed, the permit is valid for 45 days. Aggrieved parties wishing to appeal the approval of a tree permit may submit a tree appeal application and $100 fee to the Parks and Recreation Department.

Applicants shall submit written statements or landscape plans to describe how they will fulfill the replacement tree requirements. The submissions shall include: (a) the replacement tree species, (b) the container size, (c) the planting location, and (d) an in-lieu fee payment, if applicable.

Replacement trees shall receive supplemental irrigation for a period of two years or until established. Install a 2-4-inch layer of wood chip mulch around the tree dripline of new trees, and all established trees. Keep mulch away from the trunk of newly planted trees. Keep mulch a minimum of 2-feet from the trunk of established tree.

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Certificate of Performance
I, Kurt Fouts, certify:

That I have personally inspected the tree(s) and/or the property referred to in this report and have stated my findings accurately to the best of my professional judgement.  That I have no current interest in the vegetation or the property that is the subject of this report, and I have no personal interest or bias with respect to the parties involved.  That the analysis, opinions and conclusions stated herein are my own, and were developed and prepared according to commonly accepted arboricultural practices.  That my compensation is not contingent upon the reporting of a predetermined conclusion that favors the cause of the client or any other party, nor upon the results of the assessment, the attainment of stipulated results, or the occurrence of any subsequent events.
 That my analysis, opinions, and conclusions were developed, and this report has been prepared according to commonly accepted arboricultural practices.  That no one provided significant professional assistance to the consultant, except as indicated within the report.

I further certify that I am an International Society of Arboriculture Certified Arborist and carry an International Society of Arboriculture Tree Risk Assessment Qualification. I have been involved in the practice of arboriculture and the care and study of trees for more than 20 years.

Signed:________________________ Date: ______________________ 4/30/2024

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CONCLUSION
 A six story multi-family apartment building is proposed at 530, 542 and 548 Ocean Street, Santa Cruz. I surveyed six Heritage trees on the property, or with canopies that overhang the subject property. A Heritage tree is protected as defined by the City of Santa Cruz Ordinance.
 The Heritage trees are in good or fair condition and are suitable for incorporation into the project.
 One Heritage tree, T13, walnut, will have moderate construction impacts, can be incorporated into the project, and will require mitigation methods to reduce construction impacts.
 Five Heritage trees including T3, queen palm, T5 and T6, fan palm, T9, Layland cypress, and T12, incense cedar, are in direct conflict with the project and their removal will be necessary to accommodate construction of the building.  This report assesses anticipated impacts to affected trees and is based on a preliminary site plan. Depending on revisions to the preliminary site plan, impacts to trees may change and will require reassessment. Once the final plan set is completed, a Tree Protection Plan will be required and shall be included with the final plan set.
 The Tree Assessment Chart, Appendix A is the condensed reference guide to inform all tree management decisions for the trees evaluated.

RECOMMENDATIONS

1. Obtain all necessary permits prior to removing or significantly altering any trees on site.

2. If the owners of trees on the adjacent lots agree to remove highly impacted trees, consider using the appraised value of the offsite trees as compensation.

Respectfully submitted,
Kurt Fouts ISA Certified Arborist WE0681
ISA Tree Risk Assessment Qualification (TRAQ)

43.604

Tree # Species
Trunk
Diameter
@ 54
inches
a.g.

Heritage
Tree
Crown
Height &
Spread
(diameter)
Health
Rating
Structural
Rating Age
Suitability for
Preservation
(Based Upon
Condition &
Species)
Tree
Protection
Zone (in
radius feet)
Construction
Impacts (Rating
& Description)
Retention
or Removal
Code
Comments
T1 evergreen pear
(Pyrus kawakamii ) 13.75 No 35'X35' Fair Fair
Semimature
Fair 15' High (In building
footprint) R.I. Strong trunk bow. Surface roots are lifting parking curb.

T2 glossy privet
(Ligustrum lucidum ) 6" No 10'X10' Good Fair
Semimature
Good 10' High (In building
footprint) R.I.

Page 1 of 3 ends

Poor: Trees in poor health and/or with poor structure that cannot be effectively abated with treatment
530, 542 & 548 Ocean Street, Santa Cruz
Tree Assessment Chart - Appendix A
Suitability for Preservation Ratings: Disposition Category:

Good: Trees in good health and structural condition with potential for longevity on the site
RT: Retain Tree
RI: Remove Due to Construction Impacts
Fair: Trees in fair health and/or with structural defects that may be reduced with treatment procedures
I.M. Impacts Can Be Mitigated With Pre-Construction Treatments R.C. Remove Due to Condition
Protected Tree City of Santa Cruz Any tree 14 inches or greater in diameter measured at 4.5 feet above grade. Street trees regardless of size.

43.605
Tree # Species
Trunk
Diameter @
54 inches
a.g.

Heritage
Tree
Crown
Height
(feet)&
Spread
(diameter
feet)
Health
Rating
Structural
Rating Age
Suitability for
Preservation
(Based Upon
Condition &
Species)
Tree
Protection
Zone (in
radius feet)
Construction
Impacts (Rating &
Description)
Retention
or Removal
Code
Comments
T3
queen palm
(Syagrus
romanzoffiana )

14.5" Yes 35'X15' Good Good SemimatureGood 10' High (In building footprint) R.I.

T4 queen palm 11" No 60'x45' Good Good Semimature
Good 10' High (In building
footprint) R.I.

T5 fan palm
(Washingtonia spp .) 19" Yes 35'X10 Good Good Semimature Good 10' High (In building
footprint) R.I.

T6 fan palm 22" Yes 30'X10' Good Good Semimature
Good 10' High (In building
footprint) R.I.

T7 queen palm 11" No 30'X10' Fair Fair
Semimature
Fair 10' High (In building
footprint) R.I.

T8 queen palm 12" No 30'X10' Good Good Semimature
Good 10' High (In building
footprint) R.I.

Page 2 of 3 ends

530, 542 & 548 Ocean Street, Santa Cruz
Tree Assessment Chart - Appendix A

43.606
Tree # Species
Trunk
Diameter @
54 inches
a.g.

Approximately 2' from new building foundation. Needs
clearance pruning to accommodate project. Remove=al of
approximately 25-35% of canopy, including 6 ea. 3-6-inch diameter limbs is necessary to accommodate building.

T10 Leyland cypress 11"
(Estimated) No 50'X15' Fair Fair
Semimature
Fair 15'
High ( Canopy
Loss, clearance
pruning, Root Loss,
excavation)
R.I.

Approximately 2' from new building foundation. Needs
clearance pruning to accommodate project. Removal of
approximately 25-35% of canopy, including 4 ea. 2-4-inch diameter limbs is necessary to accommodate building.

T11 Leyland cypress 13"
(Estimated) No 50'X15' Fair Fair
Semimature
Fair 15'
High ( Canopy
Loss, clearance
pruning, Root Loss,
excavation)
R.I.

Approximately 2' from new building foundation. Needs
clearance pruning to accommodate project. Removal
approximately 25-35% of canopy, including 6 ea. 3-5-inch diameter limbs removed at trunk is necessary to
accommodate building.

T12 incense cedar
(Calocedrus decurrens)
24"
(Estimated) Yes 55'X15' Fair Fair-Poor Mature Fair 20'
High ( Canopy
Loss, clearance
pruning, Root Loss,
excavation)
R.I.

Approximately 3.5' from new building foundation. 10 - 15 degree trunk lean. Unbalanced canopy with weight bias
towards subject lot. All live growth is at outer edges of canopy. Needs clearance pruning to accommodate project.

Removal of approximately 65-75% of canopy is necessary to accommodate building.

T13
walnut
(Julgans spp .)
30"
(Estimated) Yes 50'X30' Fair Fair Mature Fair 20'
Moderate (Root
Loss, excavation,
Canopy Loss,
clearance pruning)
R.T., I.M.

Approximately 8.5' from new building foundation. Topped at 35' above grade. Needs clearance pruning to accommodate project. Removal of approximately 15-20% of canopy is
necessary to accommodate building.

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Trees On Adjacent Properties
530, 542 & 548 Ocean Street, Santa Cruz
Tree Assessment Chart - Appendix A

43.607
APPENDIX B – CRITERIAFORTREE ASSESSMENT CHART
Following is an explanation of the data used in the tree evaluations. The data is incorporated in the Tree Assessment Chart, Appendix A.

Trunk Diameter and Number of Trunks:

Trunk diameter as measured at 4.5 feet above grade. The number of trunks refers to a single or multiple trunked tree. Multiple trunks are measured at 4.5 feet above grade.

Health Ratings:

Good: A healthy, vigorous tree, reasonably free of signs and symptoms of disease Fair: Moderate vigor, moderate twig and small branch dieback, crown may be thinning and leaf color may be poor
Poor: Tree in severe decline, dieback of scaffold branches and/or trunk, most of foliage from epicormics
Structure Ratings:

Good: No significant structural defects. Growth habit and form typical of the species Fair: Moderate structural defects that might be mitigated with regular care Poor: Extensive structural defects that cannot be abated.

Relative Age:

I estimated tree age as young, semi-mature, mature, or over-mature.

Suitability for Preservation Ratings:

Rating factors:

Tree Health: Healthy vigorous trees are more tolerant of construction impacts such as root loss, grading, and soil compaction, then are less vigorous specimens.

Structural integrity: Preserved trees should be structurally sound and absent of defects or have defects that can be effectively reduced, especially near structures or high use areas.

Tree Age: Over mature trees have a reduced ability to tolerate construction impacts, generate new tissue and adjust to an altered environment. Young to maturing specimens are better able to respond to change.

Species response: There is a wide variation in the tolerance of individual tree species to construction impacts.

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Rating Scale:

Good: Trees in good health and structural condition with potential for longevity on the site Fair: Trees in fair health and/or with structural defects that may be reduced with treatment procedures.

Poor: Trees in poor health and/or with poor structure that cannot be effectively abated with treatment. Trees can be expected to decline or fail regardless of construction impacts or management . The species or individual may possess characteristics that are incompatible or undesirable in landscape settings or unsuited for the intended use of the site.

Construction Impacts:

Rating Scale:

High: Development elements proposed that are located within the Tree Protection Zone that would severely impact the health and /or stability of the tree. The tree impacts cannot be mitigated without design changes. The tree may be located within the building footprint.

Moderate: Development elements proposed that are located within the Tree Protection Zone that will impact the health and/or stability of the tree and can be mitigated with tree protection treatments.

Low: Development elements proposed that are located within or near the Tree Protection Zone that will have a minor impact on the health of the tree and can be mitigated with tree protection treatments.

None: Development elements will have no impact on the health and stability of the Tree.

Tree Protection Zone (TPZ):

Defined area within which certain activities are prohibited or restricted to prevent or minimize potential injury to designated trees, particularly during construction or development.

43.609
542 OCEAN STREET
548 OCEAN STREET
530 OCEAN STREET

OCEAN STREET

BRANCIFORTE CREEK
H:\3871-000\ACAD\EXHIBITS\XB_BASE MAP.DWG

BASE MAP

ARTHAUS OCEAN

CITY OF SANTA CRUZ SANTA CRUZ COUNTY CALIFORNIA
SCALE: 1"=10' DATE: APRIL 5, 2024
0 10 20 30 CIVIL ENGINEERS SURVEYORS PLANNERS

SAN RAMON
WWW.CBANDG.COM

ROSEVILLE
(925) 866-0322
(916) 788-4456
.
.
.
.
.
. .

Tree Location Map
530, 542, 548 Ocean Street, Santa Cruz
Sheet T1
of one sheet
K.F.
4/30/2024
A.P.N. - 010
-011-16, 31
& 30
.
.

T12 INCENSE CEDAR
24"
T13 WALNUT
30"
T9 CYPRESS
16"
T10 CYPRESS
. .
11"
T11 CYPRESS
13"
T1 EVERGREEN PEAR

13.75"
T2 PRIVET
6"
.

T3 QUEEN PALM

14.5"
T4 QUEEN PALM
11"
T5 FAN PALM
19"
T6 FAN PALM
22"
T7 QUEEN PALM
11"
T8 QUEEN PALM
12"
X
X
X X
X
X
X X
X X X X.

43.610
Glossary of Terms
Basal rot: decay of the lower trunk, trunk flare, or buttress roots.

Canker: Localized diseased area on stems, roots and branches. Often sunken and discolored.

Critical Root Zone (CRZ): Area of soil around a tree where a minimum number of roots considered critical to the structural stability or health of the tree are located. CRZ determination is sometimes based on the drip line or a multiple of the DBH, but because root growth can be asymmetric due to site conditions, on-site investigation may be required.

Codominant branches/stems: Forked branches (or trunks), nearly the same size in diameter, arising from a common junction and lacking a normal branch union, may have included bark.

Crown: Upper part of a tree, measured from the lowest branch, including all branches and foliage.

Defect: An imperfection, weakness, or lack of something necessary. In trees defects are injuries, growth patterns, decay, or other conditions that reduce the tree’s structural strength.

Diameter at breast height (DBH): Measurement of trunk diameter at 4.5 feet above grade.

Frass: Fecal material and/or wood shavings produced by insects.

Included Bark Attachments (crotches): Branch/limb or limb /trunk, or codominant trunks originating at acute angles from each other. Bark remains between such crotches, preventing the development of axillary wood. The inherent weakness of such attachments increases with time, through the pressure of opposing growth and increasing weight of wood and foliage, often resulting in failure.

Live Crown Ratio (LCR): Ratio of the the crown length (live foliage), to total tree height.

Scaffold branches: Permanent or structural branches that form the scaffold architecture or structure of a tree.

Suppressed: Trees that have been overtopped and occupy an understory position within a group or grove of trees. Suppressed trees often have poor structure.

Tree Protection Zones (TPZ): Defined area within which certain activities are prohibited of restricted to prevent or minimize potential injury to designated trees, especially during construction or development.

Trunk flare: Transition zone from trunk to roots where the trunk expands into the buttress or structural roots.

This Glossary of Terms was adapted from the Glossary of Arboricultural Terms (ISA, 2015)

43.611
P:\PKAD\Registration Office\Fee Schedule\Fees PR Facilities – Effective Jan 08, 2024 Page 12 of 13

PARKS & RECREATION DEPARTMENT

SCHEDULE OF FEES
Effective Date 01/08/2024

EVENT PERMIT FEES

PERMIT TYPE

STANDARD RATE

DEPOSITS/ MISC FEES

SIMPLE COMPLEX
Film, Video & Photography* $305 $737 💰Deposit may be required for facility access cards or keys 🍷 $67 Alcohol Permit
⚡ $34 Access to Power
💵 Commercial Use Fee (10% Standard, 5% Nonprofits)
🎟 Admissions Tax (5% Standard)
Parking Lot fees may be prorated by Permit Officer. Listed fee is a maximum.
*Application fees for student film projects are waived if they are noncommercial in orientation and content.

Major Public Event $309 $617
Public Gathering & Expression No Charge
N/A
Street Performance No Charge
Neighborhood Block Party $140
Parks & Recreation Parking Lot Use $11/space/day
Street Closure $257/day
Fees above are per approved application and do not include other fees for additional required permits, facility fees, services or staff time.

ENCROACHMENT AND TREE PERMIT FEES

PERMIT TYPE STANDARD RATE DEPOSITS/MISC FEES
Encroachment-construction/research No Charge No fee for an application. Upon approval, an Encroachment Permit will be issued.

Emergency / Dead Tree Removal
Application No Charge
No fee for an Emergency or Dead tree removal application.

Upon approval, an Emergency or Dead Tree Permit will be issued.

Tree Permit Application $50 $20 for each additional tree listed on application. A 6% technology will also be applied.

Tree Mitigation Fees
Tree Bond
In-Lieu Fee
Street Trees:

In-Lieu Fee - less than 7” diameter
In-Lieu Fee - 7” and greater in diameter
$250
$1,859
$1,646
$1,859
Mitigation Fees are per tree.

For Replanting, permittee must contact the City Urban Forester, 831-420-5246 after 3 months of establishment to have the $250.00 bond returned.

In-Lieu fees support City Tree Trust Fund for off-site mitigation.

Street Tree In-Lieu Fee is based on size as noted by City Arborist/Urban Forester Tree Appeal $100 Filed with the Parks and Recreation Commission Secretary.

43.612

BIBLIOGRAPHY

Matheny, N. and Clark, J. Trees & Development – A Technical Guide to Preservation of Trees During Land Development. Champaign, IL: International Society of Arboriculture c. 1998 Costello, L.R., Watson, G., Smiley E.T. Root Management – Best Management Practices, Champaign, ILL: International Society of Arboriculture c. 2017 ANSI Board of Standards Review. A.N.S.I. (American National Standard) A300 (Part 8)- 2013 Root Management
Harris, R.W., Clark, J.R. and Matheny, N.P. Arboriculture: Integrated management of landscape tree, shrubs, and vines. 4th ed. Upper Saddle River, NJ: Prentice-Hall, Inc. c.2004 Matheny, N. and Clark, J. Evaluation of Hazard Trees in Urban Areas. Champaign, IL: Wadley Graphix Corp. c.1994
Smiley, E.T., Matheny, N., Lilly, S. Tree Risk Assessment – Best Management Practices, Champaign, ILL: International Society of Arboriculture c. 2011 Costello, L., Perry, E., & Matheny,N, Abiotic Disorders of Landscape Plants: A Diagnostic Guide Oakland, CA:UC/ANR Publications (Publication 3420) c.2003.

43.613
Appendix G- TREE PROTECTION GUIDELINES AND RESTRICTIONS Protecting Trees During Construction:
1) Before the start of site work, equipment or materials move in, clearing, excavation, construction, or other work on the site, every tree to be retained shall be securely fenced- off as delineated in approved plans. Such fences shall remain continuously in place for the duration of the work undertaken in connection with the development. 2) If the proposed development, including any site work, will encroach upon the tree protection zone, special measures shall be utilized, as approved by the project arborist, to allow the roots to obtain necessary oxygen, water, and nutrients. 3) Underground trenching shall avoid the major support and absorbing tree roots of protected trees. If avoidance is impractical, hand excavation undertaken under the supervision of the project arborist may be required. Trenches shall be consolidated to service as many units as possible. Boring/tunneling under roots should be considered as an alternative to trenching.
4) Concrete or asphalt paving shall not be placed over the root zones of protected trees, unless otherwise permitted by the project arborist.
5) Artificial irrigation shall not occur within the root zone of native oaks, unless deemed appropriate on a temporary basis by the project arborist to improve tree vigor or mitigate root loss.
6) Compaction of the soil within the tree protection zone shall be avoided. 7) Any excavation, cutting, or filling of the existing ground surface within the tree protection zone shall be minimized and subject to such conditions as the project arborist may impose. Retaining walls shall likewise be designed, sited, and constructed to minimize their impact on protected trees.
8) Burning or use of equipment with an open flame near or within the tree protection zone shall be avoided. All brush, earth, and other debris shall be removed in a manner that prevents injury to the tree.
9) Oil, gas, chemicals, paints, cement, stucco or other substances that may be harmful to trees shall not be stored or dumped within the tree protection zone of any protected tree, or at any other location on the site from which such substances might enter the tree protection zone of a protected tree.
10) Construction materials shall not be stored within the tree protection zone of a protected tree.

43.614
Project Arborist Duties and Inspection Schedule:

The project arborist is the person(s) responsible for carrying out technical tree inspections, assessment of tree health, structure and risk, arborist report preparation, consultation with designers and municipal planners, specifying tree protection measures, monitoring, progress reports and final inspection.

The Project Arborist must provide monthly tree protection monitoring inspections. During these inspections the Project Arborist should monitor the condition of the trees, verify the tree protection measures are in compliance, provide recommendations for any necessary maintenance and impact mitigation, and prepare monthly reports for City Arborist Review.

A qualified project arborist (or firm) should be designated and assigned to facilitate and insure tree preservation practices. He/she/they should perform the following inspections:

Inspection of site: Prior to equipment and materials move in, site work, demolition, landscape construction and tree removal: The project arborist will meet with the general contractor, architect / engineer, and owner or their representative to review tree preservation measures, designate tree removals, delineate the location of tree protection fencing, specify equipment access routes and materials storage areas, review the existing condition of trees and provide any necessary recommendations.

Inspection of site: During excavation or any activities that could affect trees: Inspect site during any activity within the Tree Protection Zones of preserved trees and any recommendations implemented. Assess any changes in the health of trees since last inspection.

Final Inspection of Site: Inspection of site following completion of construction. Inspect for tree health and make any necessary recommendations.

Kurt Fouts shall be the Project Arborist for this project. All scheduled inspections shall include a brief Tree Monitoring report, documenting activities and provided to the City Arborist.

Tree Protection Fencing
a. The tree protection shall be installed in compliance with the recommendations in the Arborist Report.
b. Then the Project Arborist should visit the property, verify that the protection measures are in compliance, take photos, and then prepare a brief verification letter for City Arborist review.

Tree Protection fencing shall be installed prior to the arrival of construction equipment or materials. Fence shall be comprised of six -foot chain link fence mounted on eight - foot tall, 1 and 7/8-inch diameter galvanized posts, driven 24 inches into the ground and spaced on a minimum of 10-foot centers. Once established, the fence must remain undisturbed and be maintained throughout the construction process until final inspection.

A final inspection by the City Arborist at the end of the project will be required prior to removing any tree protection fencing.

43.615
Tree Protection Signs
All sections of fencing should be clearly marked with signs stating that all areas within the fencing are Tree Protection Zones and that disturbance is prohibited.

Monitoring
Any trenching, construction or demolition that is expected to damage or encounter tree roots should be monitored by the project arborist or a qualified ISA Certified Arborist and should be documented.

The site should be evaluated by the project arborist or a qualified ISA Certified Arborist after construction is complete, and any necessary remedial work that needs to be performed should be noted.

Root Pruning
Root pruning shall be supervised by the project arborist. When roots over two inches in diameter are encountered they should be pruned by hand with loppers, handsaw, reciprocating saw, or chain saw rather than left crushed or torn. Roots should be cut beyond sinker roots or outside root branch junctions and be supervised by the project arborist. When completed, exposed roots should be kept moist with burlap or backfilled within one hour.

Tree Work Standards and Qualifications
All tree work, removal, pruning, planting, shall be performed using industry standards of workmanship as established in the Best Management Practices of the International Society of Arboriculture (ISA) and the American National Standards Institute series, Safety Requirements in Arboriculture Operations ANSI Z133-2017, Contractor licensing and insurance coverage shall be verified.

During tree removal and clearance, sections of the Tree Protection Fencing may need to be temporarily dismantled to complete removal and pruning specifications. After each section is completed, the fencing is to be re-installed.

Trees to be removed shall be cut into smaller manageable pieces consistent with safe arboricultural practices, and carefully removed so as not to damage any surrounding trees or structures. The trees shall be cut down as close to grade as possible. Tree removal is to be performed by a qualified contractor with valid City Business/ State Licenses and General Liability and Workman’s Compensation insurance.

43.616
Development Site Tree Health Care Measures

RECOMMENDED TO PROVIDE OPTIMUM GROWING CONDITIONS, PHYSIOLOGICAL

INVIGORATION AND STAMINA, FOR PROTECTION AND RECOVERY FROM CONSTRUCTION IMPACT.

Establish and maintain TPZ fencing, trunk and scaffold limb barriers for protection from mechanical damage, and other tree protection requirements as specified in the arborist report.

Project arborist to specify site-specific soil surface coverings (wood chip mulch or other) for prevention of soil compaction and loss of root aeration capacity.

Soil, water and drainage management is to follow the ISA BMP for "Managing Trees During Construction" and the ANSI Standard A300(Part 2)- 2011 Soil Management (a. Modification, b. 'Fertilization, c. Drainage.)
Fertilizer / soil amendment product(s) amounts and method of application to be specified by certified arborist.

43.617

ASSUMPTIONS AND LIMITING CONDITIONS

1. Any legal description provided by the appraiser/consultant is assumed to be correct. No responsibility is assumed for matters legal in character nor is any opinion rendered as the quality of any title.

2. The appraiser/consultant can neither guarantee nor be responsible for accuracy of information provided by others.

3. The appraiser/consultant shall not be required to give testimony or to attend court by reason of this appraisal unless subsequent written arrangements are made, including payment of an additional fee for services.

4. Loss or removal of any part of this report invalidates the entire appraisal/evaluation.

5. Possession of this report or a copy thereof does not imply right of publication or use for any purpose by any other than the person(s) to whom it is addressed without written consent of this appraiser/consultant.

6. This report and the values expressed herein represent the opinion of the appraiser/consultant, and the appraiser/consultant’s fee is in no way contingent upon the reporting of a specified value nor upon any finding to be reported.

7. Sketches. Diagrams. Graphs. Photos. Etc., in this report, being intended as visual aids, are not necessarily to scale and should not be construed as engineering reports or surveys.

8. This report has been made in conformity with acceptable appraisal/evaluation/diagnostic reporting techniques and procedures, as recommended by the International Society of Arboriculture.

9. When applying any pesticide, fungicide, or herbicide, always follow label instructions.

10. No tree described in this report was climbed, unless otherwise stated. We cannot take responsibility for any defects which could only have been discovered by climbing. A full root collar inspection, consisting of excavating around the tree to uncover the root collar and major buttress roots, was not performed, unless otherwise stated. We cannot take responsibility for any root defects which could only have been discovered by such an inspection.

CONSULTING ARBORIST DISCLOSURE STATEMENT
Arborists are tree specialists who use their education. Knowledge, training, and experience to examine trees, recommend measures to enhance the beauty and health of trees, and attempt to reduce risk of living near trees, Clients may choose to accept or disregard the recommendations of the arborist, or to seek additional advice.

Arborists cannot detect every condition that could possibly lead to the structural failure of a tree.

Trees are living organisms that fail in ways we do not fully understand. Conditions are often hidden within trees and below ground. Arborists cannot guarantee that a tree will be healthy or safe under all circumstances, or for a specified period of time. Likewise, remedial treatments, like medicine, cannot be guaranteed.

Trees can be managed, but they cannot be controlled. To live near trees is to accept some degree of risk. The only way to eliminate all risk associated with trees is to eliminate all trees.

43.618
Exhibit B
Langan Report

43.619
1 May 2025
Mr. Chad Leege
Construction Manager
Riaz Capital
2744 E 11th Street
Oakland, California 94601
Subject: Soil, Soil Vapor, And Groundwater Assessment Letter Report 530, 542, and 548 Ocean Street
Santa Cruz, California
Langan Project No. 770697502
Dear Chad Leege:

Langan CA, Inc. (Langan) has prepared this Soil, Soil Vapor, and Groundwater Assessment Letter Report on behalf of Riaz Capital (the Client) to summarize the findings of Langan’s January 2025 Soil, Soil Vapor, and Groundwater Assessment work conducted at 530, 542, and 548 Ocean Street in Santa Cruz (the site).

Prior to Langan’s field investigation, Terraphase Engineering, Inc. (Terraphase) conducted and prepared a Phase II Environmental Investigation Report dated 22 March 2024. The results of the 2024 Terraphase Phase II ESA identified potential constituents of concern (COCs) at the site that warrant additional investigation prior to residential redevelopment, which included arsenic in shallow soil at concentrations up to 30 milligrams per kilogram (mg/kg) at 530, 542 and 548 Ocean Street. Additionally, volatile organic compounds (VOCs) consisting of chloroform and tetrachloroethene (PCE) were detected at concentrations up to 400 micrograms per cubic meter (µg/m3) and 100 µg/m3, respectively, in soil gas at 548 Ocean Street.

Langan’s 2025 subsurface investigation revealed that soil concentrations do not exceed State of California or Federal (RCRA) Hazardous waste criteria, and if excavated, can be disposed of as non-hazardous material. Concentrations of heavy metals such as chromium and lead in soil, did not surpass the non-RCRA hazardous waste thresholds. Although arsenic levels exceeded residential and commercial/industrial screening levels, they were below background concentrations, with the exception of one, isolated sample location (EB-3) between the surface and 5.0 feet below ground surface (bgs). Therefore, soil excavated during construction in the vicinity of EB-3 up to 5.0 feet bgs, a maximum volume of approximately 600 cubic yards of soil, may need to be disposed of as Class II non-hazardous material at a regulated landfill.

Groundwater was encountered at depths between 7.7 to 10.7 feet bgs. Localized dewatering may be necessary for deeper foundation elements. Groundwater contained arsenic, barium, chromium, lead, and nickel at concentrations exceeding Department of Toxic Substances Control (DTSC) and United State Environmental Protection Agency (USEPA) maximum contaminant levels (MCLs), however, there is no evidence that such groundwater impacts originated on the site or will be exacerbated by the proposed construction, including the anticipated dewatering.

43.620
Soil, Soil Vapor, and Groundwater Assessment Letter Report 530, 542, and 548 Ocean Street
Santa Cruz, California
Langan Project No. 770697502
1 May 2025

Page 2 of 2 ends

Additional groundwater sampling will likely be needed if dewatering permits from the City of Santa Cruz Department of Public Works are required for discharging groundwater to sanitary sewer or storm drain systems.

Soil vapor results from the investigation indicated the presence of VOCs including chloroform and PCE, detected at concentrations up to 4.4 µg/m3and 52 µg/m3, respectively, above residential DTSC screening levels (SLs) and/or USEPA regional screening levels (RSLs). PCE was detected above both residential and commercial/industrial screening levels in sub-slab soil vapor at a maximum concentration of 150 µg/m3. It is Langan’s opinion that off-site sources may be contributing to the presence of VOCs in soil vapor at the site. It is Langan’s opinion that the contaminants present on-site do not originate from a source at the site, that there is no risk of contaminants spreading by the proposed construction, or of the neighboring community, future residential occupants, or the adjacent Branciforte Creek being exposed to the contaminants present at the site in soil, groundwater, and soil vapor based on the construction or operation of the proposed residential redevelopment. A nearby regulatory case listings suggest that the site is downgradient of a migratory soil vapor contaminant plume with detected PCE concentrations up to 11,000 µg/m3(607-609 Soquel Avenue).

It is Langan’s opinion that implementation of the site management plan (SMP) prepared for the site is sufficient for residential development of the site, with no remedial or corrective actions warranted. The SMP was prepared by a professional engineer (PE) and a professional geologist (PG). It is our opinion that the levels of contaminants on site do not pose a significant threat to human health, or the environment and the site can be managed without regulatory oversight. To be conservative, Langan recommends installing a chemical-resistant vapor barrier membrane beneath the building slab and sealing below-grade utility conduits to prevent VOC migration. The vapor barrier membrane materials and design will be reviewed by a registered professional engineer (PE) in the State of California.

Sincerely,
Langan CA, Inc.

Mukta Patil, PE Brendan Hayward, PG
Associate Project Geologist
Peter J. Cusack
Associate Principal

43.621
Brittany Inclan
From: Bonnie Bush
Sent: Wednesday, June 18, 2025 2:21 PM
To: City Council
Subject: FW: 530 Ocean St Question/Comment Received
Bonnie Bush, CMC
City Clerk - City of Santa Cruz
809 Center St., Room 8, Santa Cruz, CA 95060
Phone: 831-420-5035
Email: [email protected]
Web: www.cityofsantacruz.com

Public Records Requests may be submitted online via the Public Records Request form, by email, or by hard copy form available at the City Clerk’s Office located at 809 Center Street, Room 8, Santa Cruz, CA 95060.

Please note: Public Record Act Requests submitted via email, fax, USPS, or dropoff after 5:00 p.m. on a business day, Saturdays, Sundays, or holidays will be processed as received on the next open business day. The 10-day response period begins when the request is received.

From: Rina Zhou <[email protected]>
Sent: Wednesday, June 18, 2025 2:19 PM
To: Bonnie Bush <[email protected]>
Subject: FW: 530 Ocean St Question/Comment Received
Hi Bonnie,
Please see below for public correspondence for the 530 Ocean St project.

Thank you!
Rina
Rina Zhou, RPP, MCIP
Senior Planner
City of Santa Cruz | Planning and Community Development Department 809 Center Street, Room 101, Santa Cruz, CA 95060
Direct: 831-420-5104 | Main Line: 831-420-5110
Email: [email protected]
Web: cityofsantacruz.com
From: [email protected] <[email protected]> Sent: Monday, June 16, 2025 1:24 PM

43.622
To: Rina Zhou <[email protected]>
Subject: 530 Ocean St Question/Comment Received
A new entry to a form/survey has been submitted.

Form Name: 530 Ocean Street
Date & Time: 06/16/2025 1:24 PM
Response #: 56
SubmiƩer ID: 116782
IP address: 63.249.96.204
Time to complete: 52 min. , 51 sec.

Survey Details

Page 1 ends

Thank you for your interest in the proposed project for 530, 542, and 548 Ocean Street (CP24-0071). Please provide any project related quesƟon or comment in the fields provided. Your comment/quesƟon will be automaƟcally directed to the City Planner assigned to this project. Please note that quesƟons and/or comments entered here are public informaƟon and subject to release in accordance with the Public Records Act.

1. Select what applies:
[×] I have a comment(s).

2. If you have a quesƟon that needs a response, please enter your email address or phone number.

Email: Not answered
Phone: Not answered

3. Please select one of the following regarding the nature of your comment:
(○) In Support

4. QuesƟon/Comment:

Nice use of color, looks like a great project. Can we get increased density though? We have already blown past the missing middle, let's grow up.

Thank you,
City of Santa Cruz
This is an automated message generated by Granicus. Please do not reply directly to this email.

43.623
1 Julia Wood
From: Eric Grabiel <[email protected]>
Sent: Thursday, June 19, 2025 12:58 PM
To: Bonnie Bush; City Council
Cc: Elise Cossart-Daly
Subject: Supplemental documents to 530 Ocean Street Appeal Honorable Councilmembers,
On behalf of the Branciforte Creek and May Ave Neighbors, I would like to submit the following four documents for the record related to the Proposed Development at 530, 542, 548 Ocean Street, Santa Cruz, California 95060

1. 530 Ocean Street DTSC Toxins site report

2. 2019 Environmental Screening Levels Tables – Chloroform

3. 2019 Environmental Screening Level Users Guide

4. State of CA – CA EPA Dept of SCTC
Thank you,
Branciforte Creek and May Ave Neighbors

43.624
2 Julia Wood
From: Eric Grabiel <[email protected]>
Sent: Thursday, June 19, 2025 1:25 PM
To: Bonnie Bush; City Council
Cc: Elise Cossart-Daly
Subject: Re: Supplemental documents to 530 Ocean Street Appeal Attachments: 2019 Environmental Screening Level Tables - Chloroform.pdf; 530 Ocean Street DTSC Toxins site report.pdf; State of CA – CA EPA Dept of SCTC.pdf; 2019 Environmental Screening Level Users Guide.pdf
Dear Councilmembers,
The following four attachments were mistakenly left off the prior email. I have attached them here.

Thank you.

On Thu, Jun 19, 2025 at 12:57 PM Eric Grabiel <[email protected]> wrote:

Honorable Councilmembers,
On behalf of the Branciforte Creek and May Ave Neighbors, I would like to submit the following four documents for the record related to the Proposed Development at 530, 542, 548 Ocean Street, Santa Cruz, California 95060

1. 530 Ocean Street DTSC Toxins site report

2. 2019 Environmental Screening Levels Tables – Chloroform

3. 2019 Environmental Screening Level Users Guide

4. State of CA – CA EPA Dept of SCTC
Thank you,
Branciforte Creek and May Ave Neighbors

43.625
ARTHAUS OCEAN (60003825) SIGN UP FOR EMAIL
530 AND 542 OCEAN STREET
SANTA CRUZ, CA 95060

SANTA CRUZ COUNTY
SITE TYPE: VOLUNTARY AGREEMENT
PROJECT MANAGER: BENJAMIN WO
SUPERVISOR: RUTH CAYABY
OFFICE: CLEANUP

SACRAMENTO
CENSUS TRACT: 6087100800
CALENVIROSCREEN PERCENTILE SCORE: 20-25%
Site Information

CLEANUP STATUS
ACTIVE AS OF 10/1/2024
SITE TYPE: VOLUNTARY AGREEMENT
NATIONAL PRIORITIES LIST: NO
ACRES: 0.8 ACRES
APN: NONE SPECIFIED
CLEANUP OVERSIGHT AGENCIES:

DTSC - SITE CLEANUP PROGRAM - LEAD AGENCY
ENVIROSTOR ID: 60003825
SITE CODE: 202510
SPECIAL PROGRAM:

FUNDING: SITE PROPONENT
ASSEMBLY DISTRICT: , 28
SENATE DISTRICT: , 17
Regulatory Profile

PAST USE(S) THAT CAUSED CONTAMINATION

NONE SPECIFIED

POTENTIAL CONTAMINANTS OF CONCERN

ARSENIC

CHLOROFORM

TETRACHLOROETHYLENE (PCE)

POTENTIAL MEDIA AFFECTED

SOIL, SOIL VAPOR
Site History
Up to date as of 6/04/2025 BW
The site is a collection of parcels zoned as Community Commercial Districts, totaling approximately 0.8 acres. Currently, the site is divided among 3 addresses: 530, 542, and 548 Ocean Street. Currently, each of these address are occupied by various commercial buildings, whose tenants include law offices, medical clinics, and social service offices. The site is located in predominantly commercial area, and bounded to the east by single family homes, to the south by a hotel and retail spaces, to the west by Ocean Street, and to the north by Branciforte c followed by a multifamily residence.

The current facilities at the site were constructed between 1956 and 1968, and expanded between 1982 and 1993. Prior to 1982, 542 Ocean Street was used for residential purposes.

The project proponent plans to demolish existing structures at the site, and construct a 6-floor multifamily residence. No residential use is planned for the first floor. As of the time of this update, the expected start date for construction / demolition is 11/30/26.

A 2023 preliminary investigation discovered contaminated soil at the site, including:
- Arsenic up to 30 mg/kg in soil near the southern border of 542 Ocean Street - Chloroform vapors up to 400 ug/m^3 in soil in the eastern portion of 548 Ocean Street - Tetrachloroethylene (PCE) vapors up to 100 ug/m^3 in soil in the eastern portion of 548 Ocean Street A follow up investigation conducted in January 2025 detected no arsenic or chloroform above commercial / industrial screening levels, but did detect PCE above commercial / industrial screening levels in the sub-slab soil vapor.

As of the time of this update, no source or responsible party associated with this contamination has been identified. From at least 1969 to 1982 a dry cleaning facility operated within 475 southeast of the site. From at least 1992 to 2001, a print shop known to handle benzene, trichloroethylene (TCE), and PCE operated within 500 feet southeast of the site. An active waterboard site, "Former Classic Cleaners", is approximately 900 feet west of the site. PCE has been detected at this site above regulatory limits in groundwater and soil vapor.

In March, 2024, the project proponent submitted an Application for Agency Oversight to DTSC, and a draft CLRRA agreement was prepared. In April 2025, the proponent withdrew their application, and the original agreement was never executed. In May, 2025, following an appeal to the issuance of the project's building permit, the Santa Cruz Planning Department issue additional conditions to the issuance of the building permit, requiring DTSC oversight remedial activities and review of construction plans. The proponent subsequently submitted an upda Application for Agency Oversight. As of the time of this update, this application is being reviewed by DTSC.

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https://www.envirostor.dtsc.ca.gov/public/profile_report?global_id=60003825 43.627 2/2 Chemicals CAS No. Groundwater
(µg/L)
Soil
(mg/kg)
Subslab / Soil Gas
(µg/m3
)
Indoor Air
(µg/m3)
Acenaphthene [PAH] 83-32-9 1.5E+01 1.2E+01 1.7E+04 5.1E+02 Acenaphthylene [PAH] 208-96-8 1.5E+01 6.4E+00 -- --
Acetone 67-64-1 1.5E+03 9.2E-01 1.0E+06 3.1E+04
Aldrin 309-00-2 1.4E-04 2.4E-03 1.9E-02 5.7E-04
Anthracene [PAH] 120-12-7 7.3E-01 1.9E+00 -- --
Antimony 7440-36-0 6.0E+00 1.1E+01 -- --
Arsenic 7440-38-2 1.0E+01 6.7E-02 -- --
Barium 7440-39-3 1.0E+03 3.9E+02 -- --
Benzene 71-43-2 4.2E-01 2.5E-02 3.2E+00 9.7E-02
Benzo[a]anthracene [PAH] 56-55-3 1.7E-02 6.3E-01 3.1E-01 9.2E-03 Benzo[b]fluoranthene [PAH] 205-99-2 4.9E-02 1.1E+00 -- -- Benzo[k]fluoranthene [PAH] 207-08-9 4.9E-02 2.8E+00 -- -- Benzo[g,h,i]perylene [PAH] 191-24-2 1.0E-01 2.5E+00 -- -- Benzo[a]pyrene [PAH] 50-32-8 1.4E-02 1.1E-01 -- --
Beryllium 7440-41-7 2.7E+00 5.0E+00 -- --
1,1-Biphenyl 92-52-4 5.0E-01 4.2E-01 1.4E+01 4.2E-01
Bis(2-chloroethyl) ether 111-44-4 6.3E-03 3.4E-05 1.3E-01 4.0E-03 Bis(2-chloro-1-methylethyl) ether 108-60-1 3.6E-01 5.1E-03 9.4E+00 2.8E-01 Bis(2-ethylhexyl) phthalate 117-81-7 4.0E+00 8.0E-01 -- -- Boron 7440-42-8 1.6E+00 1.2E+02 -- --
Bromodichloromethane 75-27-4 8.7E-01 1.6E-02 2.5E+00 7.6E-02 Bromoform (Tribromomethane) 75-25-2 8.0E+01 6.9E-01 8.5E+01 2.6E+00 Bromomethane 74-83-9 7.5E+00 3.6E-01 1.7E+02 5.2E+00
Cadmium (soil) 7440-43-9 -- 1.9E+00 -- --
Cadmium (water) 7440-43-9 2.5E-01 -- -- --
Carbon tetrachloride 56-23-5 6.1E-02 1.1E-02 2.2E+00 6.7E-02 Chlordane 12789-03-6 5.9E-04 8.5E-03 2.8E-01 8.3E-03
p-Chloroaniline 106-47-8 3.6E-01 6.7E-03 -- --
Chlorobenzene 108-90-7 2.5E+01 1.4E+00 1.7E+03 5.2E+01
Chloroethane 75-00-3 1.6E+01 1.2E+00 3.5E+05 1.0E+04
Chloroform 67-66-3 8.1E-01 2.3E-02 4.1E+00 1.2E-01
Chloromethane 74-87-3 1.9E+02 1.1E+01 3.1E+03 9.4E+01
2-Chlorophenol 95-57-8 1.8E-01 1.2E-02 6.3E+02 1.9E+01
Chromium (total) 7440-47-3 5.0E+01 1.6E+02 -- --
Chromium III 16065-83-1 1.8E+02 1.2E+05 -- --
Chromium VI 18540-29-9 2.0E-02 3.0E-01 -- --
Chrysene [PAH] 218-01-9 4.9E-02 2.2E+00 -- --
Cobalt 7440-48-4 3.0E+00 2.3E+01 -- --
Copper 7440-50-8 3.1E+00 1.8E+02 -- --
Cyanide 57-12-5 1.0E+00 3.4E-03 2.8E+01 8.3E-01
Dibenz[a,h]anthracene [PAH] 53-70-3 2.5E-02 1.1E-01 -- -- Dibromochloromethane 124-48-1 4.6E+01 4.7E-01 -- --
1,2-dibromo-3-chloropropane 96-12-8 2.8E-02 5.9E-04 5.6E-03 1.7E-04 1,2-Dibromoethane 106-93-4 5.0E-02 5.3E-04 1.6E-01 4.7E-03 1,2-Dichlorobenzene 95-50-1 1.4E+01 1.0E+00 7.0E+03 2.1E+02 1,3-Dichlorobenzene 541-73-1 6.5E+01 6.0E+00 -- --
1,4-Dichlorobenzene 106-46-7 2.6E+00 2.0E-01 8.5E+00 2.6E-01 3,3-Dichlorobenzidine 91-94-1 4.6E-02 2.5E-02 -- --
DDD 72-54-8 8.4E-04 2.7E+00 -- --
DDE 72-55-9 5.9E-04 3.3E-01 9.6E-01 2.9E-02
DDT 50-29-3 5.9E-04 1.1E-03 -- --
1,1-Dichloroethane 75-34-3 5.0E+00 2.0E-01 5.8E+01 1.8E+00 1,2-Dichloroethane 107-06-2 5.0E-01 7.0E-03 3.6E+00 1.1E-01 1,1-Dichloroethene 75-35-4 3.2E+00 5.4E-01 2.4E+03 7.3E+01 cis-1,2-Dichloroethene 156-59-2 6.0E+00 1.9E-01 2.8E+02 8.3E+00 trans-1,2-Dichloroethene 156-60-5 1.0E+01 6.5E-01 2.8E+03 8.3E+01 2,4-Dichlorophenol 120-83-2 3.0E-01 7.5E-03 4.7E+04 1.4E+03 1,2-Dichloropropane 78-87-5 2.3E+00 6.5E-02 9.4E+00 2.8E-01 Tier 1 ESLs 1
Based on a generic conceptual site model designed for use at most sites2 January 2019
1 of 3 Tier 1 ESL 43.628
Chemicals CAS No. Groundwater
(µg/L)
Soil
(mg/kg)
Subslab / Soil Gas
(µg/m3
)
Indoor Air
(µg/m3)
Tier 1 ESLs 1
Based on a generic conceptual site model designed for use at most sites2 January 2019
1,3-Dichloropropene 542-75-6 5.0E-01 1.7E-02 5.8E+00 1.8E-01 Dieldrin 60-57-1 1.4E-04 4.6E-04 2.0E-02 6.1E-04
Diethyl phthalate 84-66-2 1.5E+00 2.5E-02 -- --
Dimethyl phthalate 131-11-3 1.5E+00 3.5E-02 -- --
2,4-Dimethylphenol 105-67-9 1.0E+02 8.1E+00 3.3E+01 1.0E+00 2,4-Dinitrophenol 51-28-5 3.9E+01 3.0E+00 -- --
2,4-Dinitrotoluene 121-14-2 2.4E-01 2.3E-02 -- --
1,4-Dioxane 123-91-1 3.8E-01 1.7E-04 1.2E+01 3.6E-01
Dioxin (2,3,7,8-TCDD) 1746-01-6 1.4E-08 4.8E-06 2.5E-06 7.4E-08 Endosulfan 115-29-7 8.7E-03 9.8E-03 -- --
Endrin 72-20-8 2.3E-03 1.1E-03 -- --
Ethylbenzene 100-41-4 3.5E+00 4.3E-01 3.7E+01 1.1E+00
Fluoranthene [PAH] 206-44-0 8.0E+00 6.9E-01 -- --
Fluorene [PAH] 86-73-7 3.9E+00 6.0E+00 -- --
Heptachlor 76-44-8 2.1E-04 1.2E-01 7.2E-02 2.2E-03
Heptachlor epoxide 1024-57-3 1.1E-04 1.8E-04 3.6E-02 1.1E-03 Hexachlorobenzene 118-74-1 7.7E-04 8.0E-04 1.8E-01 5.5E-03 Hexachlorobutadiene 87-68-3 1.4E-01 2.8E-02 4.3E+00 1.3E-01 g-Hexachlorocyclohexane (Lindane) 58-89-9 1.6E-02 7.4E-03 -- -- Hexachloroethane 67-72-1 3.3E-01 1.9E-02 8.5E+00 2.6E-01 Indeno[1,2,3-c,d]pyrene [PAH] 193-39-5 4.9E-02 4.8E-01 -- -- Lead 7439-92-1 2.5E+00 3.2E+01 -- --
Mercury (elemental) 7439-97-6 2.5E-02 1.3E+01 1.0E+00 3.1E-02 Methoxychlor 72-43-5 3.0E-03 1.3E-02 -- --
Methylene chloride 75-09-2 5.0E+00 1.2E-01 3.4E+01 1.0E+00 Methyl ethyl ketone 78-93-3 5.6E+03 6.1E+00 1.7E+05 5.2E+03 Methyl isobutyl ketone 108-10-1 1.2E+02 3.6E-01 1.4E+04 4.2E+02 Methyl mercury 22967-92-6 3.0E-03 3.4E-02 -- --
2-Methylnaphthalene 91-57-6 2.1E+00 8.8E-01 2.3E+03 6.8E+01 Methyl tertiary butyl ether (MTBE) 1634-04-4 5.0E+00 2.8E-02 3.6E+021.1E+01 Molybdenum 7439-98-7 1.0E+02 6.9E+00 -- --
Naphthalene [PAH] 91-20-3 1.7E-01 4.2E-02 2.8E+00 8.3E-02 Nickel 7440-02-0 8.2E+00 8.6E+01 -- --
Pentachlorophenol 87-86-5 1.0E+00 1.3E-02 -- --
Perchlorate 7790-98-9 6.0E+00 5.5E+01 -- --
Petroleum - Gasoline -- 1.0E+02 1.0E+02 3.3E+03 1.0E+02 Petroleum - Stoddard Solvent -- 1.0E+02 1.0E+02 1.1E+04 3.3E+02 Petroleum - Jet Fuel -- 1.0E+02 1.0E+02 1.1E+04 3.3E+02 Petroleum - Diesel -- 1.0E+02 2.6E+02 8.9E+03 2.7E+02
Petroleum - HOPs -- 1.0E+02 -- -- --
Petroleum - Motor Oil -- -- 1.0E+02 -- --
Phenanthrene [PAH] 85-01-8 4.6E+00 7.8E+00 1.8E+03 5.5E+01 Phenol 108-95-2 5.0E+00 1.6E-01 5.2E+03 1.6E+02
Polychlorinated biphenyls (PCBs) 1336-36-3 1.7E-04 2.3E-01 1.6E-01 4.9E-03 Pyrene [PAH] 129-00-0 2.0E+00 4.5E+01 -- --
Selenium 7782-49-2 5.0E-01 2.4E+00 -- --
Silver 7440-22-4 1.9E-01 2.5E+01 -- --
Styrene 100-42-5 1.0E+01 9.2E-01 3.1E+04 9.4E+02
tert-Butyl alcohol 75-65-0 1.2E+01 7.5E-02 -- --
1,1,1,2-Tetrachloroethane 630-20-6 5.7E-01 1.7E-02 1.3E+01 3.8E-01 1,1,2,2-Tetrachloroethane 79-34-5 1.0E+00 1.8E-02 1.6E+00 4.8E-02 Tetrachloroethene 127-18-4 6.4E-01 8.0E-02 1.5E+01 4.6E-01 Thallium 7440-28-0 2.0E+00 7.8E-01 -- --
Toluene 108-88-3 4.0E+01 3.2E+00 1.0E+04 3.1E+02
Toxaphene 8001-35-2 2.0E-04 5.1E-01 -- --
1,2,4-Trichlorobenzene 120-82-1 5.0E+00 1.2E+00 7.0E+01 2.1E+00 1,1,1-Trichloroethane 71-55-6 6.2E+01 7.0E+00 3.5E+04 1.0E+03 2 of 3 Tier 1 ESL 43.629
Chemicals CAS No. Groundwater
(µg/L)
Soil
(mg/kg)
Subslab / Soil Gas
(µg/m3
)
Indoor Air
(µg/m3)
Tier 1 ESLs 1
Based on a generic conceptual site model designed for use at most sites2 January 2019
1,1,2-Trichloroethane 79-00-5 5.0E+00 7.6E-02 5.8E+00 1.8E-01 Trichloroethene 79-01-6 1.2E+00 8.5E-02 1.6E+01 4.8E-01 2,4,5-Trichlorophenol 95-95-4 1.1E+01 2.9E+00 -- --
2,4,6-Trichlorophenol 88-06-2 6.3E-01 4.0E-02 1.0E+01 3.0E-01 1,2,3-Trichloropropane 96-18-4 5.0E-03 1.1E-04 1.0E+01 3.1E-01 Vanadium 7440-62-2 1.9E+01 1.8E+01 -- --
Vinyl chloride 75-01-4 8.6E-03 1.5E-03 3.2E-01 9.5E-03
Xylenes 1330-20-7 2.0E+01 2.1E+00 3.5E+03 1.0E+02
Zinc 7440-66-6 8.1E+01 3.4E+02 -- --
Notes:

Abbreviations:

DDD - Dichlorodiphenyldichloroethane
DDE - Dichlorodiphenyldichloroethene
DDT - Dichlorodiphenyltrichloroethane
PAH - Polycyclic aromatic hydrocarbon
TCDD - Tetrachlorodibenzodioxin
2 - Generic Conceptual Site Model - See User's Guide Chapter 2. Input settings are:

Land Use = Residential
Groundwater Use = Drinking Water Resource
MCL Priority over Risk-Based Levels = Yes
Discharge to Surface Water = Saltwater & Freshwater
Vegetation Level = Substantial
Soil Exposure Depth = Shallow
1 - ESLs are developed based on methodologies discussed in the User's Guide. Evaluation of laboratory detection limits and naturally occurring background or ambient concentrations should be independently conducted. See User's Guide Chapter 12 (Additional Considerations) for further information.

HOPs - Hydrocarbon Oxidation Products (biodegradation metabolites and photo-oxidation products of petroleum hydrocarbons). See User's Guide Chapter 4 for further information.
3 of 3 Tier 1 ESL 43.630
MCL
Priority1
Tapwater
Cancer
Risk
Tapwater
Noncancer
Hazard
Fresh
Water
Ecotox
Saltwater
Ecotox
Seafood
Ingestion
Human
Health
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Drinking
Water
NonDrinking
Water
Acenaphthene [PAH] 83-32-9 5.3E+02 -- 5.3E+02 2.3E+01 1.5E+01 2.7E+03 -- -- -- -- 2.0E+03 2.0E+01 2.0E+02 1.5E+01 Aquatic Habitat Acenaphthylene [PAH] 208-96-8 -- -- -- -- 1.5E+01 -- -- -- -- -- 2.0E+03 -- -- 1.5E+01 Aquatic Habitat Acetone 67-64-1 1.4E+04 -- 1.4E+04 1.5E+03 -- -- -- 2.3E+07 -- 9.7E+07 5.0E+04 2.0E+04 2.0E+05 1.5E+03 Aquatic HabitatAldrin 309-00-2 9.2E-04 9.2E-04 2.0E-03 3.0E-01 1.3E-01 1.4E-04 3.2E-01 -- 1.4E+00 -- 8.5E+00 1.7E+01 1.7E+02 1.4E-04 Aquatic HabitatAnthracene [PAH] 120-12-7 1.8E+03 -- 1.8E+03 7.3E-01 1.5E+01 1.1E+05 -- -- -- -- 2.2E+01 -- -- 7.3E-01 Aquatic HabitatAntimony 7440-36-0 6.0E+00 -- 1.0E+00 3.0E+01 5.0E+02 4.3E+03 -- -- -- -- 5.0E+04 -- -- 6.0E+00 MCLArsenic 7440-38-2 1.0E+01 4.0E-03 7.0E-02 1.5E+02 3.6E+01 -- -- -- -- -- 5.0E+04 -- -- 1.0E+01 MCLBarium 7440-39-3 1.0E+03 -- 2.0E+03 -- -- -- -- -- -- -- 5.0E+04 -- -- 1.0E+03 MCLBenzene 71-43-2 1.0E+00 1.5E-01 5.7E+00 4.6E+01 3.5E+02 7.1E+01 4.2E-01 1.4E+01 1.8E+00 5.7E+01 5.0E+04 1.7E+02 2.0E+04 4.2E-01 Vapor IntrusionBenzo[a]anthracene [PAH] 56-55-3 1.7E-02 1.7E-02 -- 2.7E-02 1.5E+01 4.9E-02 1.9E+01 -- 2.3E+02 -- 4.7E+00 -- -- 1.7E-02 Tap Canc-RiskBenzo[b]fluoranthene [PAH] 205-99-2 2.5E-01 2.5E-01 -- -- 1.5E+01 4.9E-02 -- -- -- -- 7.5E-01 -- -- 4.9E-02 Aquatic HabitatBenzo[k]fluoranthene [PAH] 207-08-9 2.5E+00 2.5E+00 -- 3.7E+00 1.5E+01 4.9E-02 -- -- -- -- 4.0E-01 -- -- 4.9E-02 Aquatic HabitatBenzo[g,h,i]perylene [PAH] 191-24-2 -- -- -- 1.0E-01 1.5E+01 -- -- -- -- -- 1.3E-01 -- -- 1.0E-01 Aquatic Habitat Benzo[a]pyrene [PAH] 50-32-8 2.0E-01 7.0E-03 6.0E+00 1.4E-02 1.5E+01 4.9E-02 -- -- -- -- 8.0E-01 -- -- 1.4E-02 Aquatic HabitatBeryllium 7440-41-7 4.0E+00 -- 1.0E+00 2.7E+00 -- -- -- -- -- -- 5.0E+04 -- -- 2.7E+00 Aquatic Habitat 1,1-Biphenyl 92-52-4 8.3E-01 3.8E+00 8.3E-01 1.4E+01 -- -- -- 3.2E+01 -- 1.3E+02 3.8E+03 5.0E-01 5.0E+00 5.0E-01 Odor/Nuis Bis(2-chloroethyl) ether 111-44-4 6.3E-03 6.3E-03 -- 6.1E+01 -- 1.4E+00 5.6E+00 -- 2.5E+01 -- 5.0E+04 3.6E+02 3.6E+03 6.3E-03 Tap Canc-RiskBis(2-chloro-1-methylethyl) ether 108-60-1 3.6E-01 3.6E-01 7.1E+02 6.1E+01 -- 1.7E+05 9.4E+01 -- 4.1E+02 -- 5.0E+04 3.2E+02 3.2E+03 3.6E-01 Tap Canc-RiskBis(2-ethylhexyl) phthalate 117-81-7 4.0E+00 5.6E+00 4.0E+02 3.2E+01 -- 5.9E+00 -- -- -- -- 1.4E+02 -- -- 4.0E+00 MCLBoron 7440-42-8 1.0E+03 -- 1.0E+03 1.6E+00 -- -- -- -- -- -- 5.0E+04 -- -- 1.6E+00 Aquatic HabitatBromodichloromethane 75-27-4 8.0E+01 1.2E-01 3.8E+02 1.1E+03 3.2E+03 -- 8.7E-01 -- 3.8E+00 -- 5.0E+04 -- -- 8.7E-01 Vapor Intrusion Bromoform (Tribromomethane) 75-25-2 8.0E+01 2.9E+00 3.8E+02 1.1E+03 3.2E+03 3.6E+02 1.2E+02 -- 5.1E+02 -- 5.0E+04 5.1E+02 5.1E+03 8.0E+01 MCLBromomethane 74-83-9 7.5E+00 -- 7.5E+00 1.6E+02 3.2E+03 4.0E+03 -- 1.7E+01 -- 7.3E+01 5.0E+04 -- -- 7.5E+00 Tap NC-HazardCadmium (soil) 7440-43-9 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Cadmium (water) 7440-43-9 5.0E+00 -- 4.0E-02 2.5E-01 9.3E+00 -- -- -- -- -- 5.0E+04 -- -- 2.5E-01 Aquatic HabitatCarbon tetrachloride 56-23-5 5.0E-01 1.0E-01 3.6E+01 2.4E+02 3.2E+03 4.4E+00 6.1E-02 3.8E+01 2.7E-01 1.6E+02 5.0E+04 5.2E+02 5.2E+03 6.1E-02 Vapor IntrusionChlordane 12789-03-6 1.0E-01 1.3E-02 1.3E+00 4.3E-03 4.0E-03 5.9E-04 4.1E+00 3.7E+02 1.8E+01 1.5E+03 2.8E+01 2.5E+00 2.5E+01 5.9E-04 Aquatic Habitat p-Chloroaniline 106-47-8 3.6E-01 3.6E-01 7.6E+01 5.0E+00 -- -- -- -- -- -- 5.0E+04 -- -- 3.6E-01 Tap Canc-RiskChlorobenzene 108-90-7 7.0E+01 -- 7.0E+01 2.5E+01 6.5E+01 2.1E+04 -- 4.0E+02 -- 1.7E+03 5.0E+04 5.0E+01 5.0E+02 2.5E+01 Aquatic HabitatChloroethane 75-00-3 2.1E+04 -- 2.1E+04 -- -- -- -- 2.3E+04 -- 9.7E+04 5.0E+04 1.6E+01 1.6E+02 1.6E+01 Odor/NuisChloroform 67-66-3 8.0E+01 2.2E-01 9.7E+01 6.2E+02 3.2E+03 4.7E+02 8.1E-01 6.8E+02 3.6E+00 2.9E+03 5.0E+04 2.4E+03 2.4E+04 8.1E-01 Vapor IntrusionChloromethane 74-87-3 1.9E+02 -- 1.9E+02 1.1E+03 3.2E+03 -- -- 2.6E+02 -- 1.1E+03 5.0E+04 -- -- 1.9E+02 Tap NC-Hazard2-Chlorophenol 95-57-8 9.1E+01 -- 9.1E+01 4.4E+02 -- 4.0E+02 -- -- -- -- 5.0E+04 1.8E-01 1.8E+00 1.8E-01 Odor/NuisChromium (total) 7440-47-3 5.0E+01 -- -- 1.8E+02 -- -- -- -- -- -- 5.0E+04 -- -- 5.0E+01 MCL Chromium III 16065-83-1 2.2E+04 -- 2.2E+04 1.8E+02 1.0E+03 -- -- -- -- -- 5.0E+04 -- -- 1.8E+02 Aquatic Habitat Chromium VI 18540-29-9 2.0E-02 2.0E-02 4.4E+01 1.1E+01 5.0E+01 -- -- -- -- -- 5.0E+04 -- -- 2.0E-02 Tap Canc-RiskChrysene [PAH] 218-01-9 2.5E+01 2.5E+01 -- 3.5E-01 1.5E+01 4.9E-02 -- -- -- -- 1.0E+00 -- -- 4.9E-02 Aquatic HabitatCobalt 7440-48-4 6.0E+00 -- 6.0E+00 3.0E+00 -- -- -- -- -- -- 5.0E+04 -- -- 3.0E+00 Aquatic HabitatCopper 7440-50-8 1.0E+03 -- 3.0E+02 9.0E+00 3.1E+00 -- -- -- -- -- 5.0E+04 1.0E+03 -- 3.1E+00 Aquatic Habitat Basis
January 2019
Chemicals CAS No.

Residential
Summary of Groundwater ESLs (µg/L)
Aquatic Habitat Goal Levels
(Table GW-2)
Direct Exposure
Human Health Risk Levels
(Table GW-1)
Odor Nuisance
Levels
(Table GW-5) Gross Contamination
Levels
(GW-4)
Groundwater Vapor Intrusion Human Health
Risk Levels
(Table GW-3)
Commercial/Industrial GW
Tier 1
ESL
Cyanide 57-12-5 1.5E+02 -- 1.5E+00 5.2E+00 1.0E+00 2.2E+05 -- 2.0E+02 -- 8.3E+02 5.0E+04 1.7E+02 1.7E+03 1.0E+00 Aquatic HabitatDibenz[a,h]anthracene [PAH] 53-70-3 2.5E-02 2.5E-02 -- 7.5E+00 1.5E+01 4.9E-02 -- -- -- -- 1.3E+00 -- -- 2.5E-02 Tap Canc-RiskDibromochloromethane 124-48-1 8.0E+01 8.7E-01 3.8E+02 1.1E+03 3.2E+03 4.6E+01 -- -- -- -- 5.0E+04 -- -- 4.6E+01 Aquatic Habitat1,2-dibromo-3-chloropropane 96-12-8 2.0E-01 3.0E-04 3.7E-01 -- -- -- 2.8E-02 3.5E+01 3.4E-01 1.5E+02 5.0E+04 1.0E+01 1.0E+02 2.8E-02 Vapor Intrusion1,2-Dibromoethane 106-93-4 5.0E-02 7.5E-03 1.7E+00 1.4E+03 -- -- 1.7E-01 3.1E+01 7.6E-01 1.3E+02 5.0E+04 -- -- 5.0E-02 MCL1,2-Dichlorobenzene 95-50-1 1.0E+02 -- 3.0E+02 1.4E+01 6.5E+01 1.7E+04 -- 2.7E+03 -- 1.1E+04 5.0E+04 1.0E+02 1.0E+02 1.4E+01 Aquatic Habitat1,3-Dichlorobenzene 541-73-1 6.0E+02 -- 6.0E+02 7.1E+01 6.5E+01 2.6E+03 -- -- -- -- 5.0E+04 -- -- 6.5E+01 Aquatic Habitat 1,4-Dichlorobenzene 106-46-7 5.0E+00 4.8E-01 5.7E+02 1.5E+01 6.5E+01 2.6E+03 2.6E+00 8.4E+03 1.1E+01 3.5E+04 4.1E+04 5.0E+00 1.1E+02 2.6E+00 Vapor Intrusion3,3-Dichlorobenzidine 91-94-1 4.6E-02 4.6E-02 -- 2.5E+02 -- 7.7E-02 -- -- -- -- 1.6E+03 -- -- 4.6E-02 Tap Canc-RiskDDD 72-54-8 3.1E-02 3.1E-02 -- 1.0E-03 1.0E-03 8.4E-04 -- -- -- -- 4.5E+01 -- -- 8.4E-04 Aquatic HabitatDDE 72-55-9 4.6E-02 4.6E-02 -- 1.0E-03 1.0E-03 5.9E-04 1.7E+01 -- 7.4E+01 -- 2.0E+01 -- -- 5.9E-04 Aquatic HabitatDDT 50-29-3 2.3E-01 2.3E-01 1.0E+01 1.0E-03 1.0E-03 5.9E-04 -- -- -- -- 2.8E+00 3.5E+02 3.5E+03 5.9E-04 Aquatic Habitat1,1-Dichloroethane 75-34-3 5.0E+00 2.7E+00 3.8E+03 4.7E+01 -- -- 7.6E+00 -- 3.3E+01 -- 5.0E+04 -- -- 5.0E+00 MCL 1,2-Dichloroethane 107-06-2 5.0E-01 1.7E-01 1.3E+01 1.0E+04 1.1E+04 9.9E+01 2.2E+00 1.5E+02 9.8E+00 6.4E+02 5.0E+04 7.0E+03 2.0E+05 5.0E-01 MCL1,1-Dichloroethene 75-35-4 6.0E+00 -- 1.0E+01 2.5E+01 2.2E+04 3.2E+00 -- 6.6E+01 -- 2.8E+02 5.0E+04 1.5E+03 1.5E+04 3.2E+00 Aquatic Habitatcis-1,2-Dichloroethene 156-59-2 6.0E+00 -- 1.1E+01 5.9E+02 2.2E+04 -- -- 4.9E+01 -- 2.1E+02 5.0E+04 -- -- 6.0E+00 MCL trans-1,2-Dichloroethene 156-60-5 1.0E+01 -- 5.0E+01 5.9E+02 2.2E+04 1.4E+05 -- 2.2E+02 -- 9.2E+02 5.0E+04 2.6E+02 2.6E+03 1.0E+01 MCL2,4-Dichlorophenol 120-83-2 4.6E+01 -- 4.6E+01 1.8E+02 -- 7.9E+02 -- -- -- -- 5.0E+04 3.0E-01 3.0E+00 3.0E-01 Odor/Nuis 1,2-Dichloropropane 78-87-5 5.0E+00 4.4E-01 8.3E+00 2.9E+03 1.5E+03 3.9E+01 2.3E+00 3.5E+01 1.0E+01 1.5E+02 5.0E+04 1.0E+01 1.0E+02 2.3E+00 Vapor Intrusion1,3-Dichloropropene 542-75-6 5.0E-01 2.0E-01 3.9E+01 1.2E+02 7.9E+01 1.7E+03 1.2E+00 1.4E+02 5.1E+00 5.8E+02 5.0E+04 -- -- 5.0E-01 MCLDieldrin 60-57-1 7.1E-04 7.1E-04 2.0E-03 5.6E-02 1.9E-03 1.4E-04 1.5E+00 -- 6.5E+00 -- 1.0E+02 4.1E+01 4.1E+02 1.4E-04 Aquatic HabitatDiethyl phthalate 84-66-2 1.5E+04 -- 1.5E+04 1.5E+00 1.7E+00 1.2E+54 -- -- -- -- 5.0E+04 -- -- 1.5E+00 Aquatic HabitatDimethyl phthalate 131-11-3 -- -- -- 1.5E+00 1.7E+00 2.9E+06 -- -- -- -- 5.0E+04 -- -- 1.5E+00 Aquatic Habitat2,4-Dimethylphenol 105-67-9 1.0E+02 -- 1.0E+02 5.3E+02 1.1E+02 2.3E+03 -- -- -- -- 5.0E+04 4.0E+02 4.0E+03 1.0E+02 Tap NC-Hazard2,4-Dinitrophenol 51-28-5 3.9E+01 -- 3.9E+01 7.5E+01 4.9E+02 1.4E+04 -- -- -- -- 5.0E+04 -- -- 3.9E+01 Tap NC-Hazard2,4-Dinitrotoluene 121-14-2 2.4E-01 2.4E-01 3.8E+01 1.2E+02 1.9E+02 9.1E+00 -- -- -- -- 5.0E+04 -- -- 2.4E-01 Tap Canc-Risk1,4-Dioxane 123-91-1 3.8E-01 3.8E-01 5.7E+01 3.4E+05 5.0E+05 -- 1.8E+03 1.6E+05 8.0E+03 6.6E+05 5.0E+04 2.3E+05 -- 3.8E-01 Tap Canc-RiskDioxin (2,3,7,8-TCDD) 1746-01-6 3.0E-05 1.2E-07 1.2E-05 5.0E-06 -- 1.4E-08 3.7E-05 2.1E-02 1.6E-04 8.8E-02 1.0E-01 -- -- 1.4E-08 Aquatic HabitatEndosulfan 115-29-7 1.0E+02 -- 1.0E+02 5.6E-02 8.7E-03 2.4E+02 -- -- -- -- 1.7E+02 -- -- 8.7E-03 Aquatic HabitatEndrin 72-20-8 2.0E+00 -- 3.0E-01 3.6E-02 2.3E-03 8.1E-01 -- -- -- -- 1.3E+02 4.1E+01 4.1E+02 2.3E-03 Aquatic HabitatEthylbenzene 100-41-4 3.0E+01 1.5E+00 3.0E+02 2.9E+02 4.3E+01 2.9E+04 3.5E+00 3.3E+03 1.5E+01 1.4E+04 5.0E+04 3.0E+01 3.0E+02 3.5E+00 Vapor IntrusionFluoranthene [PAH] 206-44-0 8.0E+02 -- 8.0E+02 8.1E+00 8.0E+00 3.7E+02 -- -- -- -- 1.3E+02 -- -- 8.0E+00 Aquatic HabitatFluorene [PAH] 86-73-7 2.9E+02 -- 2.9E+02 3.9E+00 1.5E+01 1.4E+04 -- -- -- -- 8.5E+02 -- -- 3.9E+00 Aquatic HabitatHeptachlor 76-44-8 1.0E-02 1.4E-03 1.3E+00 3.8E-03 3.6E-03 2.1E-04 1.8E-01 -- 7.9E-01 -- 9.0E+01 2.0E+01 2.0E+02 2.1E-04 Aquatic HabitatHeptachlor epoxide 1024-57-3 1.0E-02 1.4E-03 1.2E-01 3.8E-03 3.6E-03 1.1E-04 1.3E+00 -- 5.5E+00 -- 1.0E+02 -- -- 1.1E-04 Aquatic HabitatHexachlorobenzene 118-74-1 1.0E+00 8.8E-03 1.6E+01 3.7E+00 6.5E+01 7.7E-04 7.9E-02 -- 3.4E-01 -- 3.1E+00 3.0E+03 3.0E+04 7.7E-04 Aquatic Habitat Hexachlorobutadiene 87-68-3 1.4E-01 1.4E-01 6.5E+00 4.7E+00 3.2E+00 5.0E+01 3.0E-01 -- 1.3E+00 -- 1.6E+03 6.0E+00 6.0E+01 1.4E-01 Tap Canc-Riskg-Hexachlorocyclohexane (Lindane) 58-89-9 2.0E-01 3.2E-02 3.6E+00 8.0E-02 1.6E-02 6.3E-02 -- -- -- -- 3.7E+03 1.2E+04 1.2E+05 1.6E-02 Aquatic Habitat Hexachloroethane 67-72-1 3.3E-01 3.3E-01 6.2E+00 1.2E+01 9.4E+01 8.9E+00 1.6E+00 2.0E+02 7.0E+00 8.2E+02 2.5E+04 1.0E+01 1.0E+02 3.3E-01 Tap Canc-Risk 2 of 4 GW Summary 43.632
MCL
Priority1
Tapwater
Cancer
Risk
Tapwater
Noncancer
Hazard
Fresh
Water
Ecotox
Saltwater
Ecotox
Seafood
Ingestion
Human
Health
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Drinking
Water
NonDrinking
Water
Basis
January 2019
Chemicals CAS No.

Residential
Summary of Groundwater ESLs (µg/L)
Aquatic Habitat Goal Levels
(Table GW-2)
Direct Exposure
Human Health Risk Levels
(Table GW-1)
Odor Nuisance
Levels
(Table GW-5) Gross Contamination
Levels
(GW-4)
Groundwater Vapor Intrusion Human Health
Risk Levels
(Table GW-3)
Commercial/Industrial GW
Tier 1
ESL
Indeno[1,2,3-c,d]pyrene [PAH] 193-39-5 2.5E-01 2.5E-01 -- -- 1.5E+01 4.9E-02 -- -- -- -- 9.5E-02 -- -- 4.9E-02 Aquatic HabitatLead 7439-92-1 1.5E+01 9.2E+00 2.0E-01 2.5E+00 8.1E+00 -- -- -- -- -- 5.0E+04 -- -- 2.5E+00 Aquatic HabitatMercury (elemental) 7439-97-6 2.0E+00 -- 6.1E-02 2.5E-02 2.5E-02 5.1E-02 -- 8.9E-02 -- 3.8E-01 3.0E+01 -- -- 2.5E-02 Aquatic HabitatMethoxychlor 72-43-5 3.0E+01 -- 9.0E-02 1.9E-02 3.0E-03 -- -- -- -- -- 5.0E+01 4.7E+03 4.7E+04 3.0E-03 Aquatic HabitatMethylene chloride 75-09-2 5.0E+00 9.3E-01 1.0E+02 2.2E+03 3.2E+03 1.6E+03 7.8E+00 3.2E+03 9.4E+01 1.3E+04 5.0E+04 9.1E+03 9.1E+04 5.0E+00 MCLMethyl ethyl ketone 78-93-3 5.6E+03 -- 5.6E+03 1.4E+04 -- -- -- 2.3E+06 -- 9.5E+06 5.0E+04 8.4E+03 8.4E+04 5.6E+03 Tap NC-HazardMethyl isobutyl ketone 108-10-1 1.2E+02 -- 1.2E+02 1.7E+02 -- -- -- 5.6E+05 -- 2.3E+06 5.0E+04 1.3E+03 1.3E+04 1.2E+02 Tap NC-HazardMethyl mercury 22967-92-6 2.0E+00 -- 2.0E+00 3.0E-03 -- -- -- -- -- -- 5.0E+04 -- -- 3.0E-03 Aquatic Habitat2-Methylnaphthalene 91-57-6 3.6E+01 -- 3.6E+01 2.1E+00 3.0E+01 -- -- -- -- -- 1.3E+04 1.0E+01 1.0E+02 2.1E+00 Aquatic HabitatMethyl tertiary butyl ether (MTBE) 1634-04-4 5.0E+00 1.3E+01 6.3E+03 6.6E+04 8.0E+03 -- 4.5E+02 1.3E+05 2.0E+03 5.5E+05 5.0E+04 5.0E+00 1.8E+03 5.0E+00 Odor/NuisMolybdenum 7439-98-7 1.0E+02 -- 1.0E+02 2.4E+02 -- -- -- -- -- -- 5.0E+04 -- -- 1.0E+02 Tap NC-HazardNaphthalene [PAH] 91-20-3 1.7E-01 1.7E-01 6.1E+00 2.4E+01 1.5E+01 -- 4.6E+00 1.7E+02 2.0E+01 7.3E+02 1.6E+04 2.1E+01 2.1E+02 1.7E-01 Tap Canc-Risk Nickel 7440-02-0 1.0E+02 1.2E+01 2.2E+02 5.2E+01 8.2E+00 4.6E+03 -- -- -- -- 5.0E+04 -- -- 8.2E+00 Aquatic Habitat Pentachlorophenol 87-86-5 1.0E+00 4.0E-02 2.3E+01 1.5E+01 7.9E+00 8.2E+00 -- -- -- -- 7.0E+03 3.0E+01 5.9E+03 1.0E+00 MCLPerchlorate 7790-98-9 6.0E+00 -- 1.0E+00 6.0E+02 -- -- -- -- -- -- 5.0E+04 -- -- 6.0E+00 MCL Petroleum - Gasoline -- 7.6E+02 -- 7.6E+02 4.4E+02 3.7E+03 -- -- -- -- -- 5.0E+04 1.0E+02 5.0E+03 1.0E+02 Odor/NuisPetroleum - Stoddard Solvent -- 2.1E+02 -- 2.1E+02 6.4E+02 6.4E+02 -- -- -- -- -- 2.5E+03 1.0E+02 5.0E+03 1.0E+02 Odor/Nuis Petroleum - Jet Fuel -- 2.1E+02 -- 2.1E+02 6.4E+02 6.4E+02 -- -- -- -- -- 2.5E+03 1.0E+02 5.0E+03 1.0E+02 Odor/NuisPetroleum - Diesel -- 2.0E+02 -- 2.0E+02 6.4E+02 6.4E+02 -- -- -- -- -- 2.5E+03 1.0E+02 5.0E+03 1.0E+02 Odor/NuisPetroleum - HOPs -- 4.1E+02 -- 4.1E+02 5.1E+02 5.1E+02 -- -- -- -- -- 5.0E+04 1.0E+02 5.0E+03 1.0E+02 Odor/NuisPetroleum - Motor Oil -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Phenanthrene [PAH] 85-01-8 -- -- -- 6.3E+00 4.6E+00 -- -- -- -- -- 4.1E+02 1.0E+03 1.0E+04 4.6E+00 Aquatic HabitatPhenol 108-95-2 4.2E+03 -- 4.2E+03 1.3E+03 5.8E+02 4.6E+06 -- -- -- -- 5.0E+04 5.0E+00 7.9E+04 5.0E+00 Odor/NuisPolychlorinated biphenyls (PCBs) 1336-36-3 5.0E-01 1.9E-03 -- 1.4E-02 3.0E-02 1.7E-04 2.9E-01 -- 1.3E+00 -- 3.5E+02 -- -- 1.7E-04 Aquatic HabitatPyrene [PAH] 129-00-0 1.2E+02 -- 1.2E+02 2.0E+00 1.5E+01 1.1E+04 -- -- -- -- 7.0E+01 -- -- 2.0E+00 Aquatic HabitatSelenium 7782-49-2 5.0E+01 -- 3.0E+01 5.0E+00 5.0E-01 -- -- -- -- -- 5.0E+04 -- -- 5.0E-01 Aquatic HabitatSilver 7440-22-4 1.0E+02 -- 9.4E+01 3.4E+00 1.9E-01 -- -- -- -- -- 5.0E+04 1.0E+02 -- 1.9E-01 Aquatic HabitatStyrene 100-42-5 1.0E+01 5.0E-01 1.1E+03 -- -- -- -- 8.5E+03 -- 3.6E+04 5.0E+04 1.0E+01 1.1E+02 1.0E+01 Odor/Nuistert-Butyl alcohol 75-65-0 1.2E+01 1.2E+01 -- 1.8E+04 -- -- -- -- -- -- 5.0E+04 -- -- 1.2E+01 Tap Canc-Risk1,1,1,2-Tetrachloroethane 630-20-6 5.7E-01 5.7E-01 4.8E+02 9.3E+02 -- -- 3.8E+00 -- 1.7E+01 -- 5.0E+04 -- -- 5.7E-01 Tap Canc-Risk1,1,2,2-Tetrachloroethane 79-34-5 1.0E+00 7.6E-02 3.6E+02 4.2E+02 9.0E+02 1.1E+01 3.2E+00 -- 1.4E+01 -- 5.0E+04 5.0E+02 5.0E+03 1.0E+00 MCLTetrachloroethene 127-18-4 5.0E+00 6.0E-02 4.1E+01 1.2E+02 2.3E+02 8.9E+00 6.4E-01 5.8E+01 2.8E+00 2.4E+02 5.0E+04 1.7E+02 3.0E+03 6.4E-01 Vapor IntrusionThallium 7440-28-0 2.0E+00 -- 1.0E-01 2.0E+01 2.1E+02 6.3E+00 -- -- -- -- 5.0E+04 -- -- 2.0E+00 MCLToluene 108-88-3 4.0E+01 -- 1.5E+02 1.3E+02 2.5E+03 2.0E+05 -- 1.2E+03 -- 4.9E+03 5.0E+04 4.0E+01 4.0E+02 4.0E+01 Odor/NuisToxaphene 8001-35-2 3.0E+00 3.0E-02 -- 2.0E-04 2.0E-04 7.5E-04 -- -- -- -- 2.8E+02 1.4E+02 1.4E+02 2.0E-04 Aquatic Habitat1,2,4-Trichlorobenzene 120-82-1 5.0E+00 1.1E+00 4.0E+00 2.5E+01 6.5E+01 -- -- 3.6E+01 -- 1.5E+02 2.5E+04 3.0E+03 3.0E+04 5.0E+00 MCL1,1,1-Trichloroethane 71-55-6 2.0E+02 -- 1.0E+03 6.2E+01 3.1E+03 -- -- 1.5E+03 -- 6.3E+03 5.0E+04 9.7E+02 5.0E+05 6.2E+01 Aquatic Habitat1,1,2-Trichloroethane 79-00-5 5.0E+00 2.8E-01 4.1E-01 4.7E+03 -- 4.2E+01 5.2E+00 6.1E+00 2.3E+01 2.6E+01 5.0E+04 -- -- 5.0E+00 MCLTrichloroethene 79-01-6 5.0E+00 4.9E-01 2.8E+00 3.6E+02 2.0E+02 8.1E+01 1.2E+00 5.2E+00 7.5E+00 2.2E+01 5.0E+04 3.1E+02 1.0E+05 1.2E+00 Vapor Intrusion 3 of 4 GW Summary 43.633
MCL
Priority1
Tapwater
Cancer
Risk
Tapwater
Noncancer
Hazard
Fresh
Water
Ecotox
Saltwater
Ecotox
Seafood
Ingestion
Human
Health
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Drinking
Water
NonDrinking
Water
Basis
January 2019
Chemicals CAS No.

MCL - Maximum Contaminant LevelNC - NoncancerOdor/Nuis - Odor NuisancePAH - Polycyclic aromatic hydrocarbonTap - TapwaterTCDD - Tetrachlorodibenzodioxin- Petroleum Motor Oil is composed of large carbon chain compounds (C24-C36+) having negligible solubility. Detections in water samples typically are Petroleum HOPs, nonaqueous phase liquid (NAPL or free product), contaminated sediment entrained in the water sample, or naturally occurring compounds. Review the chromatograms to help determine the nature of the compounds being detected. See User's Guide Chapter 4. 4 of 4 GW Summary 43.634
Significantly
Vegetated Area
Minimally
Vegetated Area
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Examples:

Parkland or
single family
homes
with yards
Examples:

High density residential or
commercial/
industrial areas
Acenaphthene [PAH] 83-32-9 -- 3.6E+03 -- 4.5E+04 -- 1.0E+04 6.6E+03 4.6E+04 1.2E+01 1.2E+01 1.2E+02 1.0E+03 2.5E+03 2.5E+03 1.2E+01 LeachingAcenaphthylene [PAH] 208-96-8 -- -- -- -- -- -- -- -- 6.4E+00 6.4E+00 5.9E+01 5.0E+02 1.0E+03 1.0E+03 6.4E+00 LeachingAcetone 67-64-1 -- 6.1E+04 -- 6.7E+05 -- 2.7E+05 5.6E+01 5.6E+01 9.2E-01 9.2E-01 1.1E+05 5.0E+02 1.0E+03 1.0E+03 9.2E-01 LeachingAldrin 309-00-2 3.5E-02 2.1E+00 1.5E-01 2.9E+01 1.0E+00 7.4E+00 2.4E-03 1.0E-01 8.4E+00 8.4E+00 8.4E+00 1.0E+03 2.5E+03 2.5E+03 2.4E-03 Terr Habitat Anthracene [PAH] 120-12-7 -- 1.8E+04 -- 2.3E+05 -- 5.0E+04 3.1E+00 4.0E+01 1.9E+00 1.9E+00 4.1E+00 5.0E+02 1.0E+03 1.0E+03 1.9E+00 LeachingAntimony 7440-36-0 -- 1.1E+01 -- 1.6E+02 -- 5.0E+01 2.5E+01 5.0E+01 -- -- -- -- -- -- 1.1E+01 NC-Hazard Arsenic 7440-38-2 6.7E-02 2.6E-01 3.1E-01 3.6E+00 2.0E+00 9.8E-01 2.5E+01 5.0E+01 -- -- -- -- -- -- 6.7E-02 Canc-Risk Barium 7440-39-3 -- 1.5E+04 -- 2.2E+05 -- 3.0E+03 3.9E+02 6.7E+02 -- -- -- -- -- -- 3.9E+02 Terr Habitat Benzene 71-43-2 3.3E-01 1.1E+01 1.4E+00 4.7E+01 3.3E+01 4.5E+01 6.0E+01 3.1E+02 2.5E-02 2.5E-02 1.9E+03 5.0E+02 1.0E+03 1.0E+03 2.5E-02 LeachingBenzo[a]anthracene [PAH] 56-55-3 1.1E+00 -- 2.0E+01 -- 1.1E+02 -- 6.3E-01 1.3E+00 1.0E+01 1.0E+01 1.0E+01 5.0E+02 1.0E+03 1.0E+03 6.3E-01 Terr HabitatBenzo[a]pyrene [PAH] 50-32-8 1.1E-01 1.8E+01 2.1E+00 2.2E+02 1.1E+01 1.0E+01 2.5E+01 9.0E+01 5.7E+00 5.7E+00 5.7E+00 5.0E+02 1.0E+03 1.0E+03 1.1E-01 Canc-RiskBenzo[b]fluoranthene [PAH] 205-99-2 1.1E+00 -- 2.1E+01 -- 1.1E+02 -- -- -- 5.4E+00 7.5E+01 5.4E+00 5.0E+02 1.0E+03 1.0E+03 1.1E+00 Canc-RiskBenzo[g,h,i]perylene [PAH] 191-24-2 -- -- -- -- -- -- 8.3E+00 1.7E+01 2.7E+01 2.7E+01 2.5E+00 5.0E+02 1.0E+03 1.0E+03 2.5E+00 Gross Contam Benzo[k]fluoranthene [PAH] 207-08-9 1.1E+01 -- 2.1E+02 -- 9.1E+02 -- 9.5E+00 1.9E+01 4.8E+00 3.9E+01 2.8E+00 5.0E+02 1.0E+03 1.0E+03 2.8E+00 Gross ContamBeryllium 7440-41-7 1.6E+03 1.6E+01 6.9E+03 2.3E+02 1.8E+02 2.7E+01 5.0E+00 1.0E+01 -- -- -- -- -- -- 5.0E+00 Terr Habitat 1,1-Biphenyl 92-52-4 6.8E+01 4.7E+01 2.9E+02 2.0E+02 1.7E+03 1.8E+02 -- -- 4.2E-01 4.2E+00 2.3E+02 5.0E+02 1.0E+03 1.0E+03 4.2E-01 Leaching Bis(2-chloroethyl) ether 111-44-4 1.0E-01 -- 4.7E-01 -- 6.4E+00 -- -- -- 3.4E-05 3.1E-02 5.0E+03 5.0E+02 1.0E+03 1.0E+03 3.4E-05 LeachingBis(2-chloro-1-methylethyl) ether 108-60-1 5.0E+00 3.1E+03 2.3E+01 4.7E+04 2.7E+02 1.4E+04 -- -- 5.1E-03 8.7E-01 1.0E+03 5.0E+02 1.0E+03 1.0E+03 5.1E-03 LeachingBis(2-ethylhexyl) phthalate 117-81-7 3.9E+01 1.3E+03 1.6E+02 1.6E+04 9.5E+02 3.8E+03 8.0E-01 3.5E+01 1.9E+02 6.4E+02 1.9E+02 5.0E+02 1.0E+03 1.0E+03 8.0E-01 Terr HabitatBoron 7440-42-8 -- 1.6E+04 -- 2.3E+05 -- 4.5E+04 1.2E+02 1.2E+02 -- -- -- -- -- -- 1.2E+02 Terr HabitatBromodichloromethane 75-27-4 2.9E-01 1.6E+03 1.3E+00 2.3E+04 2.8E+01 7.1E+03 -- -- 1.6E-02 1.6E-02 9.3E+02 1.0E+03 2.5E+03 2.5E+03 1.6E-02 Leaching Bromoform (Tribromomethane) 75-25-2 1.8E+01 1.6E+03 8.0E+01 2.3E+04 1.2E+03 7.1E+03 -- -- 6.9E-01 1.0E+00 9.2E+02 5.0E+02 1.0E+03 1.0E+03 6.9E-01 LeachingBromomethane 74-83-9 -- 6.9E+00 -- 3.0E+01 -- 2.9E+01 -- -- 3.6E-01 8.3E-01 3.5E+03 5.0E+02 1.0E+03 1.0E+03 3.6E-01 Leaching Cadmium (soil) 7440-43-9 9.1E+02 7.8E+01 4.0E+03 1.1E+03 1.1E+02 5.1E+01 1.9E+00 1.9E+00 -- -- -- -- -- -- 1.9E+00 Terr Habitat Cadmium (water) 7440-43-9 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Carbon tetrachloride 56-23-5 1.0E-01 5.3E+01 4.4E-01 2.5E+02 1.0E+01 2.2E+02 7.3E+00 1.5E+01 1.1E-02 1.1E-02 4.5E+02 5.0E+02 1.0E+03 1.0E+03 1.1E-02 LeachingChlordane 12789-03-6 4.8E-01 3.6E+01 2.2E+00 5.0E+02 1.4E+01 1.3E+02 8.5E-03 8.5E-03 2.3E+01 2.3E+01 2.3E+01 1.0E+03 2.5E+03 2.5E+03 8.5E-03 Terr Habitat p-Chloroaniline 106-47-8 3.5E+00 3.1E+02 1.6E+01 4.7E+03 1.2E+02 1.4E+03 2.5E+01 5.0E+01 6.7E-03 9.1E-02 3.0E+03 5.0E+02 1.0E+03 1.0E+03 6.7E-03 LeachingChlorobenzene 108-90-7 -- 2.7E+02 -- 1.3E+03 -- 1.2E+03 7.5E+00 1.5E+01 1.4E+00 1.4E+00 7.5E+02 5.0E+02 1.0E+03 1.0E+03 1.4E+00 LeachingChloroethane 75-00-3 -- 1.4E+04 -- 5.9E+04 -- 5.9E+04 -- -- 1.2E+00 1.2E+01 2.1E+03 5.0E+02 1.0E+03 1.0E+03 1.2E+00 LeachingChloroform 67-66-3 3.2E-01 2.0E+02 1.4E+00 1.0E+03 3.4E+01 8.6E+02 4.3E+01 8.5E+01 2.3E-02 2.3E-02 2.6E+03 5.0E+02 1.0E+03 1.0E+03 2.3E-02 Leaching Chloromethane 74-87-3 -- 1.1E+02 -- 4.7E+02 -- 4.7E+02 -- -- 1.1E+01 1.5E+01 1.3E+03 1.0E+02 5.0E+02 5.0E+02 1.1E+01 Leaching 2-Chlorophenol 95-57-8 -- 3.9E+02 -- 5.8E+03 -- 1.8E+03 2.0E+00 3.9E+00 1.2E-02 1.2E-01 2.7E+04 1.0E+02 5.0E+02 5.0E+02 1.2E-02 LeachingChromium (total) 7440-47-3 -- -- -- -- -- -- 1.6E+02 1.6E+02 -- -- -- -- -- -- 1.6E+02 Terr HabitatChromium III 16065-83-1 -- 1.2E+05 -- 1.8E+06 -- 5.3E+05 -- -- -- -- -- -- -- -- 1.2E+05 NC-HazardChromium VI 18540-29-9 3.0E-01 2.3E+02 6.2E+00 3.5E+03 2.8E+00 4.0E+02 1.0E+01 1.0E+01 -- -- -- -- -- -- 3.0E-01 Canc-Risk Chrysene [PAH] 218-01-9 1.1E+02 -- 2.1E+03 -- 9.1E+03 -- 8.8E+00 1.8E+01 2.2E+00 1.0E+01 2.2E+00 5.0E+02 1.0E+03 1.0E+03 2.2E+00 Gross ContamCobalt 7440-48-4 4.2E+02 2.3E+01 1.9E+03 3.5E+02 4.9E+01 2.8E+01 5.0E+01 1.0E+02 -- -- -- -- -- -- 2.3E+01 NC-HazardCopper 7440-50-8 -- 3.1E+03 -- 4.7E+04 -- 1.4E+04 1.8E+02 3.0E+02 -- -- -- -- -- -- 1.8E+02 Terr Habitat January 2019
Chemicals CAS No.

Odor Nuisance Levels
(Table S-5)
Summary of Soil ESLs (mg/kg)
Leaching to
Groundwater Levels
(Table S-3)
Soil
Tier 1
ESL
Basis
Gross
Contamination
Levels
(Table S-4)
Residential:

Shallow Soil
Exposure
Commerical/
Industrial:

Shallow Soil
Exposure
Construction Worker:

Any Land Use/
Any Depth Soil Exposure
Terrestrial Habitat Levels
(Table S-2)
Direct Exposure Human Health
Risk Levels (Table S-1)
Drinking
Water
Nondrinking
Water
Res:

Shallow Soil
Exposure
Com/Ind:

Shallow Soil
Exposure
Any
Land Use:

Any Soil
Exposure
(CW)
1 of 4 Soil Summary 43.635
Significantly
Vegetated Area
Minimally
Vegetated Area
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Examples:

Parkland or
single family
homes
with yards
Examples:

High density residential or
commercial/
industrial areas
January 2019
Chemicals CAS No.

Odor Nuisance Levels
(Table S-5)
Summary of Soil ESLs (mg/kg)
Leaching to
Groundwater Levels
(Table S-3)
Soil
Tier 1
ESL
Basis
Gross
Contamination
Levels
(Table S-4)
Residential:

Shallow Soil
Exposure
Commerical/
Industrial:

Shallow Soil
Exposure
Construction Worker:

Any Land Use/
Any Depth Soil Exposure
Terrestrial Habitat Levels
(Table S-2)
Direct Exposure Human Health
Risk Levels (Table S-1)
Drinking
Water
Nondrinking
Water
Res:

Shallow Soil
Exposure
Com/Ind:

Shallow Soil
Exposure
Any
Land Use:

Any Soil
Exposure
(CW)
Cyanide 57-12-5 -- 5.5E+00 -- 2.5E+01 -- 2.2E+01 1.1E-01 1.1E-01 3.4E-03 3.4E-03 1.9E+04 1.0E+02 5.0E+02 5.0E+02 3.4E-03 LeachingDibenz[a,h]anthracene [PAH] 53-70-3 1.1E-01 -- 2.1E+00 -- 1.1E+01 -- -- -- 2.9E+01 3.9E+02 2.9E+01 5.0E+02 1.0E+03 1.0E+03 1.1E-01 Canc-Risk Dibromochloromethane 124-48-1 8.3E+00 1.6E+03 3.9E+01 2.3E+04 2.9E+02 7.1E+03 -- -- 4.7E-01 1.1E+01 8.0E+02 1.0E+02 5.0E+02 5.0E+02 4.7E-01 Leaching1,2-dibromo-3-chloropropane 96-12-8 4.4E-03 4.8E+00 5.9E-02 2.6E+01 1.1E+00 2.0E+01 -- -- 5.9E-04 5.9E-04 9.9E+02 5.0E+02 1.0E+03 1.0E+03 5.9E-04 Leaching1,2-Dibromoethane 106-93-4 3.6E-02 7.2E+00 1.6E-01 3.0E+01 3.3E+00 3.0E+01 -- -- 5.3E-04 1.9E-03 1.3E+03 5.0E+02 1.0E+03 1.0E+03 5.3E-04 Leaching 1,2-Dichlorobenzene 95-50-1 -- 1.8E+03 -- 9.4E+03 -- 7.8E+03 4.3E+00 8.5E+00 1.0E+00 1.0E+00 3.8E+02 1.0E+03 2.5E+03 2.5E+03 1.0E+00 Leaching 1,3-Dichlorobenzene 541-73-1 -- -- -- -- -- -- 6.0E+00 1.2E+01 7.4E+00 7.4E+00 6.1E+02 1.0E+02 5.0E+02 5.0E+02 6.0E+00 Terr Habitat 1,4-Dichlorobenzene 106-46-7 2.6E+00 3.4E+03 1.2E+01 2.6E+04 2.8E+02 1.5E+04 4.5E+00 9.0E+00 2.0E-01 2.0E-01 1.9E+02 5.0E+02 1.0E+03 1.0E+03 2.0E-01 Leaching3,3-Dichlorobenzidine 91-94-1 5.8E-01 -- 2.7E+00 -- 2.0E+01 -- -- -- 2.5E-02 1.3E+02 6.0E+01 5.0E+02 1.0E+03 1.0E+03 2.5E-02 Leaching DDD 72-54-8 2.7E+00 -- 1.2E+01 -- 8.1E+01 -- 8.5E+00 1.7E+01 6.5E+01 6.5E+01 6.5E+01 5.0E+02 1.0E+03 1.0E+03 2.7E+00 Canc-Risk DDE 72-55-9 1.8E+00 -- 8.3E+00 -- 5.7E+01 -- 3.3E-01 6.5E-01 2.9E+01 2.9E+01 2.9E+01 5.0E+02 1.0E+03 1.0E+03 3.3E-01 Terr Habitat DDT 50-29-3 1.9E+00 3.7E+01 8.5E+00 5.2E+02 5.7E+01 1.4E+02 1.1E-03 7.8E+00 5.6E+00 5.6E+00 5.6E+00 5.0E+02 1.0E+03 1.0E+03 1.1E-03 Terr Habitat 1,1-Dichloroethane 75-34-3 3.6E+00 1.6E+04 1.6E+01 2.3E+05 3.7E+02 7.1E+04 1.1E+01 2.1E+01 2.0E-01 3.1E-01 1.7E+03 5.0E+02 1.0E+03 1.0E+03 2.0E-01 Leaching1,2-Dichloroethane 107-06-2 4.7E-01 3.2E+01 2.1E+00 1.4E+02 4.5E+01 1.3E+02 2.9E+01 2.9E+01 7.0E-03 3.1E-02 3.0E+03 1.0E+02 5.0E+02 5.0E+02 7.0E-03 Leaching 1,1-Dichloroethene 75-35-4 -- 8.3E+01 -- 3.5E+02 -- 3.5E+02 4.3E+01 1.3E+02 5.4E-01 4.2E+00 1.2E+03 5.0E+02 1.0E+03 1.0E+03 5.4E-01 Leachingcis-1,2-Dichloroethene 156-59-2 -- 1.9E+01 -- 8.5E+01 -- 7.8E+01 8.4E+01 9.4E+02 1.9E-01 1.6E+00 2.4E+03 1.0E+02 5.0E+02 5.0E+02 1.9E-01 Leaching trans-1,2-Dichloroethene 156-60-5 -- 1.3E+02 -- 6.0E+02 -- 5.7E+02 8.4E+01 9.4E+02 6.5E-01 1.4E+01 1.9E+03 5.0E+02 1.0E+03 1.0E+03 6.5E-01 Leaching 2,4-Dichlorophenol 120-83-2 -- 2.3E+02 -- 3.5E+03 -- 1.1E+03 2.1E+00 -- 7.5E-03 7.5E-02 5.6E+03 5.0E+02 1.0E+03 1.0E+03 7.5E-03 Leaching 1,2-Dichloropropane 78-87-5 1.0E+00 1.6E+01 4.4E+00 6.6E+01 9.9E+01 6.6E+01 3.1E+01 6.3E+01 6.5E-02 6.5E-02 1.4E+03 1.0E+02 5.0E+02 5.0E+02 6.5E-02 Leaching 1,3-Dichloropropene 542-75-6 5.7E-01 7.2E+01 2.5E+00 3.1E+02 5.3E+01 3.0E+02 3.1E+01 6.3E+01 1.7E-02 4.0E-02 1.6E+03 5.0E+02 1.0E+03 1.0E+03 1.7E-02 LeachingDieldrin 60-57-1 3.7E-02 3.5E+00 1.6E-01 4.8E+01 1.1E+00 1.2E+01 9.6E-04 1.1E-01 4.6E-04 6.3E-03 2.4E+01 5.0E+02 1.0E+03 1.0E+03 4.6E-04 Leaching Diethyl phthalate 84-66-2 -- 5.1E+04 -- 6.6E+05 -- 1.5E+05 1.3E+01 2.7E+01 2.5E-02 2.5E-02 7.7E+02 5.0E+02 1.0E+03 1.0E+03 2.5E-02 LeachingDimethyl phthalate 131-11-3 -- -- -- -- -- -- 2.1E+01 4.2E+01 3.5E-02 3.5E-02 4.7E+03 5.0E+02 1.0E+03 1.0E+03 3.5E-02 Leaching2,4-Dimethylphenol 105-67-9 -- 1.6E+03 -- 2.3E+04 -- 7.1E+03 -- -- 8.1E+00 8.9E+00 2.4E+04 1.0E+02 5.0E+02 5.0E+02 8.1E+00 Leaching2,4-Dinitrophenol 51-28-5 -- 1.6E+02 -- 2.3E+03 -- 7.1E+02 -- -- 3.0E+00 5.7E+00 8.0E+03 5.0E+02 1.0E+03 1.0E+03 3.0E+00 Leaching2,4-Dinitrotoluene 121-14-2 2.2E+00 1.6E+02 1.1E+01 2.3E+03 7.9E+01 7.1E+02 -- -- 2.3E-02 1.1E+01 7.2E+02 5.0E+02 1.0E+03 1.0E+03 2.3E-02 Leaching1,4-Dioxane 123-91-1 4.7E+00 8.1E+02 2.2E+01 4.5E+03 2.1E+02 3.4E+03 1.8E+00 1.8E+00 1.7E-04 8.4E-01 1.2E+05 5.0E+02 1.0E+03 1.0E+03 1.7E-04 LeachingDioxin (2,3,7,8-TCDD) 1746-01-6 4.8E-06 5.1E-05 2.2E-05 7.2E-04 1.5E-04 2.0E-04 1.3E-05 9.9E-05 3.0E-01 3.0E-01 3.0E-01 5.0E+02 1.0E+03 1.0E+03 4.8E-06 Canc-Risk Endosulfan 115-29-7 -- 4.2E+02 -- 5.8E+03 -- 1.5E+03 2.3E-02 3.8E-01 9.8E-03 9.8E-03 1.3E+01 5.0E+02 1.0E+03 1.0E+03 9.8E-03 LeachingEndrin 72-20-8 -- 2.1E+01 -- 2.9E+02 -- 7.4E+01 1.1E-03 1.1E-03 7.6E-03 7.6E-03 3.0E+01 5.0E+02 1.0E+03 1.0E+03 1.1E-03 Terr Habitat Ethylbenzene 100-41-4 5.9E+00 3.4E+03 2.6E+01 2.1E+04 5.4E+02 1.5E+04 9.0E+01 4.3E+02 4.3E-01 4.3E-01 4.9E+02 5.0E+02 1.0E+03 1.0E+03 4.3E-01 LeachingFluoranthene [PAH] 206-44-0 -- 2.4E+03 -- 3.0E+04 -- 6.7E+03 6.9E-01 1.2E+05 8.6E+01 8.6E+01 8.6E+01 5.0E+02 1.0E+03 1.0E+03 6.9E-01 Terr Habitat Fluorene [PAH] 86-73-7 -- 2.4E+03 -- 3.0E+04 -- 6.7E+03 -- -- 6.0E+00 6.0E+00 9.4E+01 5.0E+02 1.0E+03 1.0E+03 6.0E+00 LeachingHeptachlor 76-44-8 1.2E-01 3.5E+01 5.3E-01 4.8E+02 3.7E+00 1.2E+02 2.5E-01 5.0E-01 4.4E+01 4.4E+01 4.4E+01 1.0E+03 2.5E+03 2.5E+03 1.2E-01 Canc-RiskHeptachlor epoxide 1024-57-3 6.2E-02 9.1E-01 2.8E-01 1.3E+01 1.9E+00 3.2E+00 -- -- 1.8E-04 6.0E-03 1.2E+01 1.0E+03 2.5E+03 2.5E+03 1.8E-04 Leaching Hexachlorobenzene 118-74-1 1.8E-01 5.6E+01 7.8E-01 7.7E+02 7.7E+00 2.0E+02 1.3E+02 2.5E+02 8.0E-04 8.2E-02 2.3E-01 5.0E+02 1.0E+03 1.0E+03 8.0E-04 LeachingHexachlorobutadiene 87-68-3 1.2E+00 7.8E+01 5.3E+00 1.2E+03 1.0E+02 3.5E+02 -- -- 2.8E-02 6.2E-02 1.7E+01 5.0E+02 1.0E+03 1.0E+03 2.8E-02 Leaching g-Hexachlorocyclohexane (Lindane) 58-89-9 5.5E-01 2.1E+01 2.5E+00 2.9E+02 1.6E+01 7.4E+01 7.4E+00 1.5E+01 7.4E-03 7.4E-03 1.2E+02 5.0E+02 1.0E+03 1.0E+03 7.4E-03 LeachingHexachloroethane 67-72-1 1.8E+00 3.8E+01 7.8E+00 3.7E+02 1.3E+02 1.2E+02 -- -- 1.9E-02 9.2E-02 6.7E+01 5.0E+02 1.0E+03 1.0E+03 1.9E-02 Leaching 2 of 4 Soil Summary 43.636
Significantly
Vegetated Area
Minimally
Vegetated Area
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Examples:

Parkland or
single family
homes
with yards
Examples:

High density residential or
commercial/
industrial areas
January 2019
Chemicals CAS No.

Odor Nuisance Levels
(Table S-5)
Summary of Soil ESLs (mg/kg)
Leaching to
Groundwater Levels
(Table S-3)
Soil
Tier 1
ESL
Basis
Gross
Contamination
Levels
(Table S-4)
Residential:

Shallow Soil
Exposure
Commerical/
Industrial:

Shallow Soil
Exposure
Construction Worker:

Any Land Use/
Any Depth Soil Exposure
Terrestrial Habitat Levels
(Table S-2)
Direct Exposure Human Health
Risk Levels (Table S-1)
Drinking
Water
Nondrinking
Water
Res:

Shallow Soil
Exposure
Com/Ind:

Shallow Soil
Exposure
Any
Land Use:

Any Soil
Exposure
(CW)
Indeno[1,2,3-c,d]pyrene [PAH] 193-39-5 1.1E+00 -- 2.1E+01 -- 1.1E+02 -- 4.8E-01 9.5E-01 1.6E+01 3.2E+01 2.3E+00 5.0E+02 1.0E+03 1.0E+03 4.8E-01 Terr Habitat Lead 7439-92-1 8.2E+01 8.0E+01 3.8E+02 3.2E+02 2.7E+03 1.6E+02 3.2E+01 3.2E+01 -- -- -- -- -- -- 3.2E+01 Terr HabitatMercury (elemental) 7439-97-6 -- 1.3E+01 -- 1.9E+02 -- 4.4E+01 1.5E+01 2.0E+01 -- -- -- 5.0E+02 1.0E+03 1.0E+03 1.3E+01 NC-HazardMethoxychlor 72-43-5 -- 3.5E+02 -- 4.8E+03 -- 1.2E+03 1.3E-01 4.1E+03 1.3E-02 1.3E-02 1.6E+01 5.0E+02 1.0E+03 1.0E+03 1.3E-02 LeachingMethylene chloride 75-09-2 1.9E+00 3.1E+02 2.5E+01 2.5E+03 4.9E+02 1.4E+03 9.8E-01 2.0E+00 1.2E-01 1.9E-01 3.3E+03 5.0E+02 1.0E+03 1.0E+03 1.2E-01 LeachingMethyl ethyl ketone 78-93-3 -- 2.7E+04 -- 2.0E+05 -- 1.2E+05 4.4E+01 8.8E+01 6.1E+00 1.5E+01 2.8E+04 5.0E+02 1.0E+03 1.0E+03 6.1E+00 LeachingMethyl isobutyl ketone 108-10-1 -- 3.4E+04 -- 1.4E+05 -- 1.4E+05 -- -- 3.6E-01 5.1E-01 3.4E+03 1.0E+02 5.0E+02 5.0E+02 3.6E-01 LeachingMethyl mercury 22967-92-6 -- 6.3E+00 -- 8.2E+01 -- 1.9E+01 3.4E-02 3.4E-02 -- -- -- 1.0E+02 5.0E+02 5.0E+02 3.4E-02 Terr Habitat2-Methylnaphthalene 91-57-6 -- 2.4E+02 -- 3.0E+03 -- 6.7E+02 -- -- 8.8E-01 8.8E-01 3.8E+02 5.0E+02 1.0E+03 1.0E+03 8.8E-01 LeachingMethyl tertiary butyl ether (MTBE) 1634-04-4 4.7E+01 1.6E+04 2.1E+02 6.6E+04 4.1E+03 6.5E+04 3.1E+01 6.3E+01 2.8E-02 2.5E+00 9.0E+03 1.0E+02 5.0E+02 5.0E+02 2.8E-02 LeachingMolybdenum 7439-98-7 -- 3.9E+02 -- 5.8E+03 -- 1.8E+03 6.9E+00 4.0E+01 -- -- -- -- -- -- 6.9E+00 Terr Habitat Naphthalene [PAH] 91-20-3 3.8E+00 1.3E+02 1.7E+01 5.8E+02 4.0E+02 5.0E+02 7.5E-01 2.8E+01 4.2E-02 1.2E+00 2.8E+02 5.0E+02 1.0E+03 1.0E+03 4.2E-02 LeachingNickel 7440-02-0 1.5E+04 8.2E+02 6.4E+04 1.1E+04 1.7E+03 8.6E+01 1.3E+02 3.4E+02 -- -- -- -- -- -- 8.6E+01 NC-Hazard Pentachlorophenol 87-86-5 1.0E+00 2.5E+02 4.0E+00 2.8E+03 2.0E+01 5.6E+02 1.3E-02 3.9E+01 9.8E-02 7.7E-01 5.1E+01 5.0E+02 1.0E+03 1.0E+03 1.3E-02 Terr HabitatPerchlorate 7790-98-9 -- 5.5E+01 -- 8.2E+02 -- 2.5E+02 -- -- -- -- -- -- -- -- 5.5E+01 NC-Hazard Petroleum - Gasoline -- -- 4.3E+02 -- 2.0E+03 -- 1.8E+03 1.2E+02 1.2E+02 1.1E+03 4.9E+03 1.0E+03 1.0E+02 5.0E+02 5.0E+02 1.0E+02 Odor/Nuis Petroleum - Stoddard Solvent -- -- 2.6E+02 -- 1.4E+03 -- 1.1E+03 2.6E+02 2.6E+02 1.3E+03 8.0E+03 2.3E+03 1.0E+02 5.0E+02 5.0E+02 1.0E+02 Odor/NuisPetroleum - Jet Fuel -- -- 2.7E+02 -- 1.4E+03 -- 1.1E+03 2.6E+02 2.6E+02 1.3E+03 8.0E+03 2.3E+03 1.0E+02 5.0E+02 5.0E+02 1.0E+02 Odor/Nuis Petroleum - Diesel -- -- 2.6E+02 -- 1.2E+03 -- 1.1E+03 2.6E+02 2.6E+02 1.1E+03 7.3E+03 2.3E+03 5.0E+02 1.0E+03 1.0E+03 2.6E+02 NC-Hazard Petroleum - HOPs -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Petroleum - Motor Oil -- -- 1.2E+04 -- 1.8E+05 -- 5.4E+04 1.6E+03 1.6E+03 -- -- 5.1E+03 1.0E+02 5.0E+02 5.0E+02 1.0E+02 Odor/NuisPhenanthrene [PAH] 85-01-8 -- -- -- -- -- -- 7.8E+00 1.6E+01 1.1E+01 1.1E+01 6.9E+01 5.0E+02 1.0E+03 1.0E+03 7.8E+00 Terr HabitatPhenol 108-95-2 -- 2.3E+04 -- 3.5E+05 -- 9.8E+04 9.4E+00 9.4E+00 1.6E-01 1.8E+01 1.0E+05 5.0E+02 1.0E+03 1.0E+03 1.6E-01 LeachingPolychlorinated biphenyls (PCBs) 1336-36-3 2.3E-01 -- 9.4E-01 -- 5.5E+00 -- 1.1E+00 1.1E+00 3.3E+02 3.3E+02 3.3E+02 5.0E+02 1.0E+03 1.0E+03 2.3E-01 Canc-RiskPyrene [PAH] 129-00-0 -- 1.8E+03 -- 2.3E+04 -- 5.0E+03 4.7E+03 9.9E+04 4.5E+01 4.5E+01 4.5E+01 5.0E+02 1.0E+03 1.0E+03 4.5E+01 Gross ContamSelenium 7782-49-2 -- 3.9E+02 -- 5.8E+03 -- 1.7E+03 2.4E+00 5.5E+00 -- -- -- -- -- -- 2.4E+00 Terr Habitat Silver 7440-22-4 -- 3.9E+02 -- 5.8E+03 -- 1.8E+03 2.5E+01 5.0E+01 -- -- -- -- -- -- 2.5E+01 Terr HabitatStyrene 100-42-5 -- 5.7E+03 -- 3.3E+04 -- 2.5E+04 2.2E+01 4.3E+01 9.2E-01 1.0E+01 8.7E+02 5.0E+02 1.0E+03 1.0E+03 9.2E-01 Leachingtert-Butyl alcohol 75-65-0 -- -- -- -- -- -- -- -- 7.5E-02 1.1E+02 3.2E+05 1.0E+02 5.0E+02 5.0E+02 7.5E-02 Leaching 1,1,1,2-Tetrachloroethane 630-20-6 2.0E+00 2.3E+03 8.9E+00 3.5E+04 1.9E+02 1.1E+04 -- -- 1.7E-02 1.1E-01 7.0E+02 1.0E+02 5.0E+02 5.0E+02 1.7E-02 Leaching1,1,2,2-Tetrachloroethane 79-34-5 6.1E-01 1.6E+03 2.7E+00 2.3E+04 4.9E+01 7.1E+03 -- -- 1.8E-02 5.8E-02 1.9E+03 5.0E+02 1.0E+03 1.0E+03 1.8E-02 Leaching Tetrachloroethene 127-18-4 5.9E-01 8.2E+01 2.7E+00 3.9E+02 3.3E+01 3.5E+02 4.5E+00 4.3E+01 8.0E-02 8.0E-02 1.7E+02 5.0E+02 1.0E+03 1.0E+03 8.0E-02 LeachingThallium 7440-28-0 -- 7.8E-01 -- 1.2E+01 -- 3.5E+00 1.8E+00 4.5E+00 -- -- -- -- -- -- 7.8E-01 NC-HazardToluene 108-88-3 -- 1.1E+03 -- 5.3E+03 -- 4.7E+03 1.4E+02 6.6E+02 3.2E+00 1.0E+01 8.1E+02 5.0E+02 1.0E+03 1.0E+03 3.2E+00 LeachingToxaphene 8001-35-2 5.1E-01 -- 2.2E+00 -- 1.4E+01 -- -- -- 2.5E+02 2.5E+02 2.5E+02 5.0E+02 1.0E+03 1.0E+03 5.1E-01 Canc-Risk 1,2,4-Trichlorobenzene 120-82-1 2.4E+01 5.9E+01 1.1E+02 2.6E+02 8.5E+02 2.4E+02 1.6E+01 3.0E+01 1.2E+00 6.0E+00 4.2E+02 5.0E+02 1.0E+03 1.0E+03 1.2E+00 Leaching1,1,1-Trichloroethane 71-55-6 -- 1.7E+03 -- 7.3E+03 -- 7.2E+03 2.2E+01 4.4E+01 7.0E+00 7.0E+00 6.5E+02 5.0E+02 1.0E+03 1.0E+03 7.0E+00 Leaching 1,1,2-Trichloroethane 79-00-5 1.2E+00 1.5E+00 5.1E+00 6.4E+00 1.1E+02 6.3E+00 1.0E+02 2.0E+02 7.6E-02 7.9E-02 2.2E+03 1.0E+02 5.0E+02 5.0E+02 7.6E-02 LeachingTrichloroethene 79-01-6 9.5E-01 4.2E+00 6.1E+00 1.9E+01 1.3E+02 1.8E+01 8.1E+00 2.5E+02 8.5E-02 8.5E-02 7.0E+02 5.0E+02 1.0E+03 1.0E+03 8.5E-02 Leaching 3 of 4 Soil Summary 43.637
Significantly
Vegetated Area
Minimally
Vegetated Area
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Examples:

Parkland or
single family
homes
with yards
Examples:

High density residential or
commercial/
industrial areas
January 2019
Chemicals CAS No.

Odor Nuisance Levels
(Table S-5)
Summary of Soil ESLs (mg/kg)
Leaching to
Groundwater Levels
(Table S-3)
Soil
Tier 1
ESL
Basis
Gross
Contamination
Levels
(Table S-4)
Residential:

Shallow Soil
Exposure
Commerical/
Industrial:

Shallow Soil
Exposure
Construction Worker:

Any Land Use/
Any Depth Soil Exposure
Terrestrial Habitat Levels
(Table S-2)
Direct Exposure Human Health
Risk Levels (Table S-1)
Drinking
Water
Nondrinking
Water
Res:

Shallow Soil
Exposure
Com/Ind:

Shallow Soil
Exposure
Any
Land Use:

Any Soil
Exposure
(CW)
2,4,5-Trichlorophenol 95-95-4 -- 7.8E+03 -- 1.2E+05 -- 3.5E+04 5.5E+00 1.0E+01 2.9E+00 2.9E+00 1.2E+04 5.0E+02 1.0E+03 1.0E+03 2.9E+00 Leaching2,4,6-Trichlorophenol 88-06-2 9.9E+00 7.8E+01 4.7E+01 1.2E+03 3.5E+02 3.5E+02 5.5E+00 1.0E+01 4.0E-02 3.1E+01 1.9E+03 1.0E+02 5.0E+02 5.0E+02 4.0E-02 Leaching1,2,3-Trichloropropane 96-18-4 2.3E-02 4.9E+00 1.1E-01 2.1E+01 8.3E-01 2.0E+01 -- -- 1.1E-04 1.3E-04 1.4E+03 1.0E+02 5.0E+02 5.0E+02 1.1E-04 LeachingVanadium 7440-62-2 -- 3.9E+02 -- 5.8E+03 -- 4.7E+02 1.8E+01 1.8E+01 -- -- -- -- -- -- 1.8E+01 Terr Habitat Vinyl chloride 75-01-4 8.3E-03 7.0E+01 1.5E-01 3.8E+02 3.4E+00 3.0E+02 4.3E+00 8.5E+00 1.5E-03 1.5E-03 3.9E+03 5.0E+02 1.0E+03 1.0E+03 1.5E-03 LeachingXylenes 1330-20-7 -- 5.8E+02 -- 2.5E+03 -- 2.4E+03 5.5E+01 2.1E+02 2.1E+00 1.0E+01 2.7E+02 5.0E+02 1.0E+03 1.0E+03 2.1E+00 LeachingZinc 7440-66-6 -- 2.3E+04 -- 3.5E+05 -- 1.1E+05 3.4E+02 3.4E+02 -- -- -- -- -- -- 3.4E+02 Terr Habitat Notes:Abbreviations:Canc - CancerCom/Ind - Commercial/IndustrialContam - ContaminationCW - Construction WorkerDDD - DichlorodiphenyldichloroethaneDDE - DichlorodiphenyldichloroetheneDDT - DichlorodiphenyltrichloroethaneExp - ExposureHOPs - Hydrocarbon Oxidation Products (biodegradation metabolites and photo-oxidation products of petroleum hydrocarbons). See User's Guide Chapter 4 for further information.

NC - NoncancerOdor/Nuis - Odor NuisancePAH - Polycyclic aromatic hydrocarbonRes - ResidentialTCDD - TetrachlorodibenzodioxinTerr - Terrestrial - Petroleum - HOPs: Soil ESLs have not been developed at this time. - Cadmium (Water): Groundwater levels do not apply to cadmium in soil so no soil level are listed. 4 of 4 Soil Summary 43.638
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Acenaphthene [PAH] 83-32-9 -- -- -- -- 1.7E+04 1.7E+04 Odor/Nuis -- -- -- -- 5.1E+02 5.1E+02 Nuis/OdorAcenaphthylene [PAH] 208-96-8 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Acetone 67-64-1 -- 1.1E+06 -- 4.5E+06 1.0E+06 1.0E+06 Odor/Nuis -- 3.2E+04 -- 1.4E+05 3.1E+04 3.1E+04 Nuis/Odor Aldrin 309-00-2 1.9E-02 -- 8.3E-02 -- 8.8E+03 1.9E-02 Canc-Risk 5.7E-04 -- 2.5E-03 -- 2.6E+02 5.7E-04 Canc-Risk Anthracene [PAH] 120-12-7 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Antimony 7440-36-0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Arsenic 7440-38-2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Barium 7440-39-3 -- -- -- -- -- -- -- -- -- -- -- -- -- --Benzene 71-43-2 3.2E+00 1.0E+02 1.4E+01 4.4E+02 1.6E+05 3.2E+00 Canc-Risk 9.7E-02 3.1E+00 4.2E-01 1.3E+01 4.9E+03 9.7E-02 Canc-RiskBenzo[a]anthracene [PAH] 56-55-3 3.1E-01 -- 3.7E+00 -- -- 3.1E-01 Canc-Risk 9.2E-03 -- 1.1E-01 -- -- 9.2E-03 Canc-RiskBenzo[a]pyrene [PAH] 50-32-8 -- -- -- -- -- -- -- -- -- -- -- -- -- --Benzo[b]fluoranthene [PAH] 205-99-2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Benzo[g,h,i]perylene [PAH] 191-24-2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Benzo[k]fluoranthene [PAH] 207-08-9 -- -- -- -- -- -- -- -- -- -- -- -- -- --Beryllium 7440-41-7 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1,1-Biphenyl 92-52-4 -- 1.4E+01 -- 5.8E+01 2.0E+03 1.4E+01 NC-Hazard -- 4.2E-01 -- 1.8E+00 6.0E+01 4.2E-01 NC-HazardBis(2-chloroethyl) ether 111-44-4 1.3E-01 -- 5.8E-01 -- 9.6E+03 1.3E-01 Canc-Risk 4.0E-03 -- 1.7E-02 -- 2.9E+02 4.0E-03 Canc-RiskBis(2-chloro-1-methylethyl) ether 108-60-1 9.4E+00 -- 4.1E+01 -- 7.5E+04 9.4E+00 Canc-Risk 2.8E-01 -- 1.2E+00 -- 2.2E+03 2.8E-01 Canc-RiskBis(2-ethylhexyl) phthalate 117-81-7 -- -- -- -- -- -- -- -- -- -- -- -- -- --Boron 7440-42-8 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Bromodichloromethane 75-27-4 2.5E+00 -- 1.1E+01 -- 3.7E+08 2.5E+00 Canc-Risk 7.6E-02 -- 3.3E-01 -- 1.1E+07 7.6E-02 Canc-RiskBromoform (Tribromomethane) 75-25-2 8.5E+01 -- 3.7E+02 -- 4.5E+05 8.5E+01 Canc-Risk 2.6E+00 -- 1.1E+01 -- 1.3E+04 2.6E+00 Canc-RiskBromomethane 74-83-9 -- 1.7E+02 -- 7.3E+02 2.7E+06 1.7E+02 NC-Hazard -- 5.2E+00 -- 2.2E+01 8.0E+04 5.2E+00 NC-HazardCadmium (soil) 7440-43-9 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Cadmium (water) 7440-43-9 -- -- -- -- -- -- -- -- -- -- -- -- -- --Carbon tetrachloride 56-23-5 2.2E+00 1.4E+03 9.7E+00 5.8E+03 2.1E+06 2.2E+00 Canc-Risk 6.7E-02 4.2E+01 2.9E-01 1.8E+02 6.3E+04 6.7E-02 Canc-RiskChlordane 12789-03-6 2.8E-01 2.4E+01 1.2E+00 1.0E+02 2.8E+02 2.8E-01 Canc-Risk 8.3E-03 7.3E-01 3.6E-02 3.1E+00 8.4E+00 8.3E-03 Canc-Riskp-Chloroaniline 106-47-8 -- -- -- -- -- -- -- -- -- -- -- -- -- --Chlorobenzene 108-90-7 -- 1.7E+03 -- 7.3E+03 3.3E+04 1.7E+03 NC-Hazard -- 5.2E+01 -- 2.2E+02 1.0E+03 5.2E+01 NC-Hazard Chloroethane 75-00-3 -- 3.5E+05 -- 1.5E+06 1.3E+07 3.5E+05 NC-Hazard -- 1.0E+04 -- 4.4E+04 3.8E+05 1.0E+04 NC-HazardChloroform 67-66-3 4.1E+00 3.4E+03 1.8E+01 1.4E+04 1.4E+07 4.1E+00 Canc-Risk 1.2E-01 1.0E+02 5.3E-01 4.3E+02 4.2E+05 1.2E-01 Canc-RiskChloromethane 74-87-3 -- 3.1E+03 -- 1.3E+04 -- 3.1E+03 NC-Hazard -- 9.4E+01 -- 3.9E+02 -- 9.4E+01 NC-Hazard2-Chlorophenol 95-57-8 -- -- -- -- 6.3E+02 6.3E+02 Odor/Nuis -- -- -- -- 1.9E+01 1.9E+01 Nuis/OdorChromium (total) 7440-47-3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Chromium III 16065-83-1 -- -- -- -- -- -- -- -- -- -- -- -- -- --Chromium VI 18540-29-9 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Subslab/Soil Gas
Vapor Intrusion: Human Health Risk Levels
(Table SG-1)
Residential Commercial/ Industrial Residential Commercial/ Industrial January 2019
Chemicals CAS No.

Summary of Vapor ESLs
Subslab/ Soil Gas (µg/m3) Indoor Air (µg/m3)
Tier 1
ESL Basis Tier 1 ESL Basis
Odor
Nuisance
Levels
(Table IA-2)
Direct Exposure
Human Heath RiskLevels (Table IA-1)
Subslab/
Soil Gas
Vapor Intrusion:

Odor Nuisance
Levels
(Table
SG-2)
1 of 4 Vapor Summary 43.639
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Subslab/Soil Gas
Vapor Intrusion: Human Health Risk Levels
(Table SG-1)
Residential Commercial/ Industrial Residential Commercial/ Industrial January 2019
Chemicals CAS No.

Odor Nuisance
Levels
(Table
SG-2)
Chrysene [PAH] 218-01-9 -- -- -- -- -- -- -- -- -- -- -- -- -- --Cobalt 7440-48-4 -- -- -- -- -- -- -- -- -- -- -- -- -- --Copper 7440-50-8 -- -- -- -- -- -- -- -- -- -- -- -- -- --Cyanide 57-12-5 -- 2.8E+01 -- 1.2E+02 2.2E+04 2.8E+01 NC-Hazard -- 8.3E-01 -- 3.5E+00 6.5E+02 8.3E-01 NC-HazardDibenz[a,h]anthracene [PAH] 53-70-3 -- -- -- -- -- -- -- -- -- -- -- -- -- --Dibromochloromethane 124-48-1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1,2-dibromo-3-chloropropane 96-12-8 5.6E-03 7.0E+00 6.8E-02 2.9E+01 -- 5.6E-03 Canc-Risk 1.7E-04 2.1E-01 2.0E-03 8.8E-01 -- 1.7E-04 Canc-Risk1,2-Dibromoethane 106-93-4 1.6E-01 2.8E+01 6.8E-01 1.2E+02 6.7E+06 1.6E-01 Canc-Risk 4.7E-03 8.3E-01 2.0E-02 3.5E+00 2.0E+05 4.7E-03 Canc-Risk1,2-Dichlorobenzene 95-50-1 -- 7.0E+03 -- 2.9E+04 1.0E+07 7.0E+03 NC-Hazard -- 2.1E+02 -- 8.8E+02 3.1E+05 2.1E+02 NC-Hazard1,3-Dichlorobenzene 541-73-1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1,4-Dichlorobenzene 106-46-7 8.5E+00 2.8E+04 3.7E+01 1.2E+05 3.7E+04 8.5E+00 Canc-Risk 2.6E-01 8.3E+02 1.1E+00 3.5E+03 1.1E+03 2.6E-01 Canc-Risk3,3-Dichlorobenzidine 91-94-1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- DDD 72-54-8 -- -- -- -- -- -- -- -- -- -- -- -- -- --
DDE 72-55-9 9.6E-01 -- 4.2E+00 -- -- 9.6E-01 Canc-Risk 2.9E-02 -- 1.3E-01 -- -- 2.9E-02 Canc-RiskDDT 50-29-3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1,1-Dichloroethane 75-34-3 5.8E+01 -- 2.6E+02 -- 4.2E+06 5.8E+01 Canc-Risk 1.8E+00 -- 7.7E+00 -- 1.3E+05 1.8E+00 Canc-Risk1,2-Dichloroethane 107-06-2 3.6E+00 2.4E+02 1.6E+01 1.0E+03 8.1E+04 3.6E+00 Canc-Risk 1.1E-01 7.3E+00 4.7E-01 3.1E+01 2.4E+03 1.1E-01 Canc-Risk1,1-Dichloroethene 75-35-4 -- 2.4E+03 -- 1.0E+04 6.7E+07 2.4E+03 NC-Hazard -- 7.3E+01 -- 3.1E+02 2.0E+06 7.3E+01 NC-Hazardcis-1,2-Dichloroethene 156-59-2 -- 2.8E+02 -- 1.2E+03 -- 2.8E+02 NC-Hazard -- 8.3E+00 -- 3.5E+01 -- 8.3E+00 NC-Hazardtrans-1,2-Dichloroethene 156-60-5 -- 2.8E+03 -- 1.2E+04 2.2E+06 2.8E+03 NC-Hazard -- 8.3E+01 -- 3.5E+02 6.7E+04 8.3E+01 NC-Hazard2,4-Dichlorophenol 120-83-2 -- -- -- -- 4.7E+04 4.7E+04 Odor/Nuis -- -- -- -- 1.4E+03 1.4E+03 Odor/Nuis1,2-Dichloropropane 78-87-5 9.4E+00 1.4E+02 4.1E+01 5.8E+02 4.0E+04 9.4E+00 Canc-Risk 2.8E-01 4.2E+00 1.2E+00 1.8E+01 1.2E+03 2.8E-01 Canc-Risk1,3-Dichloropropene 542-75-6 5.8E+00 7.0E+02 2.6E+01 2.9E+03 1.4E+05 5.8E+00 Canc-Risk 1.8E-01 2.1E+01 7.7E-01 8.8E+01 4.2E+03 1.8E-01 Canc-RiskDieldrin 60-57-1 2.0E-02 -- 8.9E-02 -- -- 2.0E-02 Canc-Risk 6.1E-04 -- 2.7E-03 -- -- 6.1E-04 Canc-RiskDiethyl phthalate 84-66-2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Dimethyl phthalate 131-11-3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2,4-Dimethylphenol 105-67-9 -- -- -- -- 3.3E+01 3.3E+01 Odor/Nuis -- -- -- -- 1.0E+00 1.0E+00 Odor/Nuis2,4-Dinitrophenol 51-28-5 -- -- -- -- -- -- -- -- -- -- -- -- -- --2,4-Dinitrotoluene 121-14-2 -- -- -- -- -- -- -- -- -- -- -- -- -- --1,4-Dioxane 123-91-1 1.2E+01 1.0E+03 5.3E+01 4.4E+03 2.0E+07 1.2E+01 Canc-Risk 3.6E-01 3.1E+01 1.6E+00 1.3E+02 6.1E+05 3.6E-01 Canc-RiskDioxin (2,3,7,8-TCDD) 1746-01-6 2.5E-06 1.4E-03 1.1E-05 5.8E-03 -- 2.5E-06 Canc-Risk 7.4E-08 4.2E-05 3.2E-07 1.8E-04 -- 7.4E-08 Canc-RiskEndosulfan 115-29-7 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Endrin 72-20-8 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Ethylbenzene 100-41-4 3.7E+01 3.5E+04 1.6E+02 1.5E+05 6.7E+04 3.7E+01 Canc-Risk 1.1E+00 1.0E+03 4.9E+00 4.4E+03 2.0E+03 1.1E+00 Canc-RiskFluoranthene [PAH] 206-44-0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Fluorene [PAH] 86-73-7 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2 of 4 Vapor Summary 43.640
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Subslab/Soil Gas
Vapor Intrusion: Human Health Risk Levels
(Table SG-1)
Residential Commercial/ Industrial Residential Commercial/ Industrial January 2019
Chemicals CAS No.

Odor Nuisance
Levels
(Table
SG-2)
Heptachlor 76-44-8 7.2E-02 -- 3.1E-01 -- 1.0E+04 7.2E-02 Canc-Risk 2.2E-03 -- 9.4E-03 -- 3.0E+02 2.2E-03 Canc-RiskHeptachlor epoxide 1024-57-3 3.6E-02 -- 1.6E-01 -- 1.0E+04 3.6E-02 Canc-Risk 1.1E-03 -- 4.7E-03 -- 3.0E+02 1.1E-03 Canc-RiskHexachlorobenzene 118-74-1 1.8E-01 -- 8.0E-01 -- -- 1.8E-01 Canc-Risk 5.5E-03 -- 2.4E-02 -- -- 5.5E-03 Canc-RiskHexachlorobutadiene 87-68-3 4.3E+00 -- 1.9E+01 -- 4.0E+05 4.3E+00 Canc-Risk 1.3E-01 -- 5.6E-01 -- 1.2E+04 1.3E-01 Canc-Riskg-Hexachlorocyclohexane (Lindane) 58-89-9 -- -- -- -- -- -- -- -- -- -- -- ---- -- Hexachloroethane 67-72-1 8.5E+00 1.0E+03 3.7E+01 4.4E+03 -- 8.5E+00 Canc-Risk 2.6E-01 3.1E+01 1.1E+00 1.3E+02 -- 2.6E-01 Canc-RiskIndeno[1,2,3-c,d]pyrene [PAH] 193-39-5 -- -- -- -- -- -- -- -- -- -- -- -- -- --Lead 7439-92-1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Mercury (elemental) 7439-97-6 -- 1.0E+00 -- 4.4E+00 -- 1.0E+00 NC-Hazard -- 3.1E-02 -- 1.3E-01 -- 3.1E-02 NC-HazardMethoxychlor 72-43-5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Methylene chloride 75-09-2 3.4E+01 1.4E+04 4.1E+02 5.8E+04 1.9E+07 3.4E+01 Canc-Risk 1.0E+00 4.2E+02 1.2E+01 1.8E+03 5.6E+05 1.0E+00 Canc-RiskMethyl ethyl ketone 78-93-3 -- 1.7E+05 -- 7.3E+05 1.1E+06 1.7E+05 NC-Hazard -- 5.2E+03 -- 2.2E+04 3.2E+04 5.2E+03 NC-HazardMethyl isobutyl ketone 108-10-1 -- 1.0E+05 -- 4.4E+05 1.4E+04 1.4E+04 Odor/Nuis -- 3.1E+03 -- 1.3E+04 4.2E+02 4.2E+02 Odor/NuisMethyl mercury 22967-92-6 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2-Methylnaphthalene 91-57-6 -- -- -- -- 2.3E+03 2.3E+03 Odor/Nuis -- -- -- -- 6.8E+01 6.8E+01 Odor/NuisMethyl tertiary butyl ether (MTBE) 1634-04-4 3.6E+02 1.0E+05 1.6E+03 4.4E+05 1.8E+04 3.6E+02 Canc-Risk 1.1E+01 3.1E+03 4.7E+01 1.3E+04 5.3E+02 1.1E+01 Canc-RiskMolybdenum 7439-98-7 -- -- -- -- -- -- -- -- -- -- -- -- -- --Naphthalene [PAH] 91-20-3 2.8E+00 1.0E+02 1.2E+01 4.4E+02 1.5E+04 2.8E+00 Canc-Risk 8.3E-02 3.1E+00 3.6E-01 1.3E+01 4.4E+02 8.3E-02 Canc-RiskNickel 7440-02-0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Pentachlorophenol 87-86-5 -- -- -- -- -- -- -- -- -- -- -- -- -- --Perchlorate 7790-98-9 -- -- -- -- -- -- -- -- -- -- -- -- -- -- Petroleum - Gasoline -- -- 2.0E+04 -- 8.3E+04 3.3E+03 3.3E+03 Odor/Nuis -- 6.0E+02 -- 2.5E+03 1.0E+02 1.0E+02 Odor/NuisPetroleum - Stoddard Solvent -- -- 1.1E+04 -- 4.6E+04 3.3E+04 1.1E+04 NC-Hazard -- 3.3E+02 -- 1.4E+03 1.0E+03 3.3E+02 NC-HazardPetroleum - Jet Fuel -- -- 1.1E+04 -- 4.6E+04 3.3E+04 1.1E+04 NC-Hazard -- 3.3E+02 -- 1.4E+03 1.0E+03 3.3E+02 NC-HazardPetroleum - Diesel -- -- 8.9E+03 -- 3.7E+04 3.3E+04 8.9E+03 NC-Hazard -- 2.7E+02 -- 1.1E+03 1.0E+03 2.7E+02 NC-HazardPetroleum - HOPs -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Petroleum - Motor Oil -- -- -- -- -- -- -- -- -- -- -- -- -- -- --Phenanthrene [PAH] 85-01-8 -- -- -- -- 1.8E+03 1.8E+03 Odor/Nuis -- -- -- -- 5.5E+01 5.5E+01 Odor/NuisPhenol 108-95-2 -- -- -- -- 5.2E+03 5.2E+03 Odor/Nuis -- -- -- -- 1.6E+02 1.6E+02 Odor/NuisPolychlorinated biphenyls (PCBs) 1336-36-3 1.6E-01 -- 7.2E-01 -- -- 1.6E-01 Canc-Risk 4.9E-03 -- 2.2E-02 -- -- 4.9E-03 Canc-RiskPyrene [PAH] 129-00-0 -- -- -- -- -- -- -- -- -- -- -- -- -- --Selenium 7782-49-2 -- -- -- -- -- -- -- -- -- -- -- -- -- --Silver 7440-22-4 -- -- -- -- -- -- -- -- -- -- -- -- -- --Styrene 100-42-5 -- 3.1E+04 -- 1.3E+05 4.5E+04 3.1E+04 NC-Hazard -- 9.4E+02 -- 3.9E+03 1.4E+03 9.4E+02 NC-Hazardtert-Butyl alcohol 75-65-0 -- -- -- -- -- -- -- -- -- -- -- -- -- --1,1,1,2-Tetrachloroethane 630-20-6 1.3E+01 -- 5.5E+01 -- -- 1.3E+01 Canc-Risk 3.8E-01 -- 1.7E+00 -- -- 3.8E-01 Canc-Risk 3 of 4 Vapor Summary 43.641
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Cancer
Risk
Noncancer
Hazard
Subslab/Soil Gas
Vapor Intrusion: Human Health Risk Levels
(Table SG-1)
Residential Commercial/ Industrial Residential Commercial/ Industrial January 2019
Chemicals CAS No.

Odor Nuisance
Levels
(Table
SG-2)
1,1,2,2-Tetrachloroethane 79-34-5 1.6E+00 -- 7.0E+00 -- 3.5E+05 1.6E+00 Canc-Risk 4.8E-02 -- 2.1E-01 -- 1.0E+04 4.8E-02 Canc-RiskTetrachloroethene 127-18-4 1.5E+01 1.4E+03 6.7E+01 5.8E+03 1.1E+06 1.5E+01 Canc-Risk 4.6E-01 4.2E+01 2.0E+00 1.8E+02 3.2E+04 4.6E-01 Canc-RiskThallium 7440-28-0 -- -- -- -- -- -- -- -- -- -- -- -- -- --Toluene 108-88-3 -- 1.0E+04 -- 4.4E+04 1.0E+06 1.0E+04 NC-Hazard -- 3.1E+02 -- 1.3E+03 3.0E+04 3.1E+02 NC-HazardToxaphene 8001-35-2 -- -- -- -- -- -- -- -- -- -- -- -- -- --1,2,4-Trichlorobenzene 120-82-1 -- 7.0E+01 -- 2.9E+02 7.3E+05 7.0E+01 NC-Hazard -- 2.1E+00 -- 8.8E+00 2.2E+04 2.1E+00 NC-Hazard1,1,1-Trichloroethane 71-55-6 -- 3.5E+04 -- 1.5E+05 2.2E+06 3.5E+04 NC-Hazard -- 1.0E+03 -- 4.4E+03 6.5E+04 1.0E+03 NC-Hazard1,1,2-Trichloroethane 79-00-5 5.8E+00 7.0E+00 2.6E+01 2.9E+01 -- 5.8E+00 Canc-Risk 1.8E-01 2.1E-01 7.7E-01 8.8E-01 -- 1.8E-01 Canc-RiskTrichloroethene 79-01-6 1.6E+01 7.0E+01 1.0E+02 2.9E+02 4.5E+07 1.6E+01 Canc-Risk 4.8E-01 2.1E+00 3.0E+00 8.8E+00 1.4E+06 4.8E-01 Canc-Risk2,4,5-Trichlorophenol 95-95-4 -- -- -- -- -- -- -- -- -- -- -- -- -- --2,4,6-Trichlorophenol 88-06-2 -- -- -- -- 1.0E+01 1.0E+01 Odor/Nuis -- -- -- -- 3.0E-01 3.0E-01 Odor/Nuis1,2,3-Trichloropropane 96-18-4 -- 1.0E+01 -- 4.4E+01 -- 1.0E+01 NC-Hazard -- 3.1E-01 -- 1.3E+00 -- 3.1E-01 NC-HazardVanadium 7440-62-2 -- -- -- -- -- -- -- -- -- -- -- -- -- --Vinyl chloride 75-01-4 3.2E-01 3.5E+03 5.2E+00 1.5E+04 2.6E+07 3.2E-01 Canc-Risk 9.5E-03 1.0E+02 1.6E-01 4.4E+02 7.7E+05 9.5E-03 Canc-RiskXylenes 1330-20-7 -- 3.5E+03 -- 1.5E+04 1.5E+04 3.5E+03 NC-Hazard -- 1.0E+02 -- 4.4E+02 4.4E+02 1.0E+02 NC-HazardZinc 7440-66-6 -- -- -- -- -- -- -- -- -- -- -- -- -- --Abbreviations:Canc-Risk - CancerDDD - DichlorodiphenyldichloroethaneDDE - DichlorodiphenyldichloroetheneDDT - DichlorodiphenyltrichloroethaneHOPs - Hydrocarbon Oxidation Products (biodegradation metabolites and photo-oxidation products of petroleum hydrocarbons). See User's Guide Chapter 4 for further information.

NC - Noncancer Odor/Nuis - Odor NuisancePAH - Polycyclic aromatic hydrocarbonTCDD - Tetrachlorodibenzodioxin 4 of 4 Vapor Summary 43.642
January 2019
Groundwater Subslab/ Soil Gas Indoor Air Indoor Air
Trigger
Level
Trigger
Level
Accelerated
Response Level
Urgent
Response Level
(µg/L) (µg/m3) (µg/m3) (µg/m3)
Residential 5.0E+00 6.7E+01 2.0E+00 6.0E+00
Commercial 2.0E+01 2.7E+02 8.0E+00 2.4E+01
Notes:

User's Guide Chapter 6 presents the basis for the short-term action levels for TCE in groundwater, soil gas, and indoor air. - Commercial: prompt mitigation such as increasing use of HVAC (e.g., increasing outdoor air intake, increasing building pressurization), sealing potential conduits, or treating indoor air - Residential: prompt mitigation such as increasing ventilation, sealing potential conduits, or treating indoor air Short-Term Action Levels for Trichloroethene (TCE)
Land Use
Expedite
Indoor Air
Sampling
Mitigation*
within Weeks
Also see the USEPA Region 9 Memorandum Response Action Levels and Recommendations to Address Near-Term Inhalation Exposures to TCE in Air from Subsurface Vapor Intrusion (USEPA 2014d). *Mitigation - Responses include but are not limited to the following:

Mitigation*
within Days
Trigger Level
Response
Action
Urgent
Response
Action
Accelerated
Response
Action

43.643
User’s Guide:

Derivation and Application of
Environmental Screening Levels (ESLs)
INTERIM FINAL 2019
Prepared by:

San Francisco Bay Regional Water Quality Control
Board
1515 Clay Street, Suite 1400
Oakland, CA 94612

43.644
2019 ESLs UG (Rev 0) Acknowledgements-1
For Comments and Questions, Please Contact:

ESL Email ([email protected])
-orNicole Fry, PhD
San Francisco Bay Regional Water Quality Control Board
1515 Clay Street, Suite 1400
Oakland, CA 94612
Phone: 1-951-320-6366
Prepared by:

Nicole Fry, PhD, Research Scientist III, Chemical
Ross Steenson, CHG, Senior Engineering Geologist
Approved by:

David Elias, CEG, CHG, Senior Engineering Geologist
Cheryl Prowell, PE, Senior Water Resource Control Engineer Stephen Hill, Toxics Cleanup Division Chief

ACKNOWLEDGEMENTS
Numerous people have contributed to this and previous editions of the Environmental Screening Levels. The Regional Water Board would like to thank the many contributors and those who have provided comments and suggestions.

The cover photograph courtesy of John Karachewski is very much appreciated.

The photo was taken over 10 years ago at sunrise on Ring Mountain in the Marin Headlands above Kirby Cove (lower left). Mount Diablo sneaks into the upper left corner as the isolated pyramid shaped peak.

DISCLAIMER
This User’s Guide: Derivation and Application of Environmental Screening Levels is a technical report prepared by staff of the California Regional Water Quality Board, San Francisco Bay Region (Regional Water Board staff). Although this User’s Guide is not intended to establish policy or regulation, it is consistent with existing policies and regulation. The Environmental Screening Levels (ESLs) presented in this User’s Guide and the accompanying tables (Excel spreadsheets) are specifically not intended to serve as: (a) a stand-alone, decision-making tool; (b) guidance for the preparation of baseline environmental risk assessments; (c) a rule to determine if a waste is hazardous under State or federal regulations; or (d) a rule to determine when the release of hazardous chemicals must be reported to the overseeing regulatory agency.

43.645
2019 ESLs UG (Rev 0) Acknowledgements-2
In general, the ESLs are not used at sites that are subject to the Low-Threat Underground Storage Tank Closure Policy (LTCP; State Water Board 2012b).

Specifically, the LTCP does not the use the ESLs to screen contaminants at petroleum-contaminated sites. Instead the LTCP provides closure levels for carcinogens and gene ral (narrative) criteria. ESLs may be used at sites with “unique attributes” to screen for constituents not already addressed by the LTCP.

ESLs may not be adequately protective for certain sites. For example, they should not be used at sites where physical conditions or exposure scenarios substantially differ from those assumed in development of the ESLs, thereby posing a risk to human or ecological receptors. In addition, the ESLs do not apply to sediment or sensitive ecological habitats (such as wetlands or endangeredspecies habitats). The need for a detailed human health or ecological risk assessment should be evaluated on a site-by-site basis for areas where significant concerns may exist.

Use of the ESLs by dischargers or regulators is optional. Dischargers seeking to use the ESLs at their sites should discuss this with the overseeing regulatory agency. The presence of a chemical at concentrations exceeding an ESL does not necessarily indicate adverse effects on human health or the environment, rather that additional evaluation is warranted. Use of the ESLs as cleanup goals should be evaluated in view of the overall site investigation findings and the cost/benefit of performing a more site-specific evaluation (e.g., feasibility study).

The information presented in this document is not final Board action. Regional Water Board staff reserves the right to change this information at any time without public notice. This document is not intended, nor can it be relied upon, to create any rights enforceable by any party in litigation in the State of California.

Staff in overseeing regulatory agencies may decide to follow the information provided herein or act at a variance from that information, based on an analysis of site-specific circumstances.

This document will be periodically updated as needed. Regional Water Board staff overseeing work at a specific site should be contacted prior to use of this document to ensure the document is applicable and the user has the most up-todate version. This document is not copyrighted, so copies may be freely made and distributed. Reference to the ESLs without adequate review of the User’s Guide could result in misinterpretation and misuse.

43.646
2019 ESLs UG (Rev 0) i
Executive Summary
The purpose of the User’s Guide is to explain how the Environmental Screening Levels (ESLs) were derived and how they should (and should not) be used. The ESLs are composed of four elements: (1) Microsoft Excel Workbook (all tables); (2) Summary ESL Tables (PDF); (3) User’s Guide; and (4) Frequently Asked Questions (FAQs).

The ESLs allow dischargers and regulators to quickly focus on the most significant problems at contaminated sites. This review can streamline the investigation and cleanup process. We have established ESLs for over 100 commonly-found contaminants, and the ESLs address a range of media and concerns commonly found at contaminated sites. Concerns addressed by the ESLs are listed in the following Table:

Table of Concerns Addressed by ESLs
Medium
Human
Health
Drinking
Water
Resource
(Current
or
Potential)
Aquatic
Receptors
(Discharge
to Surface
Water)
Terrestrial
Receptors
(Direct
Contact)
Source
Control
Nuisance
and
Odors
Groundwater Yes Yes Yes -- Yes Yes
Soil/ Soil
Gas Yes Yes Yes Yes Yes Yes
Indoor Air Yes -- -- -- -- Yes
Users of this guide should be aware of site-specific circumstances before applying ESLs to any given site. This includes an understanding of current/future land use type, media affected by contamination, and site-specific factors (collectively, the Conceptual Site Model or “CSM”). If used correctly, ESLs are considered to be protective for typical Bay Area sites. Under most instances, and within the limitations described in the disclaimer, it’s unlikely the presence of a chemical in soil, soil gas, or groundwater at concentrations below the corresponding ESL will pose a significant threat to human health, water resources, or the environment. Additional evaluation will generally be necessary at sites where a chemical is present at concentrations above the corresponding ESL. The ESLs may be especially useful at sites where the preparation of a more formal environmental assessment may not be warranted or feasible due to time and cost constraints. The ESLs are “evergreen,” and are updated periodically.

43.647
2019 ESLs UG (Rev 0) ii
Users should review the current version of the ESLs that is posted at the Regional Water Board web site and identify the version for the record in all relevant communications.

Table of Contents
EXECUTIVE SUMMARY................................................................................. I TABLE OF CONTENTS..................................................................................II 1 INTRODUCTION AND BACKGROUND................................................ 1-1

1.1 San Francisco Bay Basin Water Quality Control Plan (Basin Plan).........1-1

1.1.1 Beneficial Uses of Surface Water and Groundwater.................1-2

1.1.2 Environmental Concerns in the Basin Plan...............................1-3

1.1.3 Investigation and Cleanup of Discharges..................................1-4

1.2 History of the ESLs .................................................................................1-5

1.3 Intended Use of the ESLs .......................................................................1-5

1.4 Comparison of ESLs to Other Screening Levels and Criteria..................1-7

1.4.1 Other Screening Levels ............................................................1-7

1.4.2 Hazardous Waste Regulations and OSHA Standards ..............1-9

1.4.3 OSHA Standards: Permissible Exposure Limits........................1-9

1.5 Site Closure Evaluations: Use of the ESLs ........................................... 1-11

1.5.1 Low-Threat Underground Storage Tank Case Closure Policy . 1-11

1.5.2 Closure Criteria for Non-UST Sites......................................... 1-12

1.6 Other Technical Documents.................................................................. 1-13 2 STEP-BY-STEP GUIDE: ESL WORKBOOK........................................... 2-1

2.1 Conceptual Site Model............................................................................2-2

2.2 ESL Workbook Content ..........................................................................2-8

2.3 Tier 1 ESLs – Default Conceptual Site Model .........................................2-9

2.4 Tier 2 ESLs – Selecting Site-Specific ESLs and Use of Interactive Tool .. 2- 10 Step 1: Check ESL Applicability and Updates....................................... 2-11 Step 2: Identify Chemicals of Potential Concern ................................... 2-11 Step 3: Land Use Selection................................................................... 2-11 Step 4: Vegetation Level Selection ....................................................... 2-12

43.648
2019 ESLs UG (Rev 0) iii
Step 5: Groundwater Use Selection...................................................... 2-13 Step 6: MCL Priority versus Risk-Based Screening Levels Selection.... 2-13 Step 7: Discharge to Surface Water Type Selection ............................. 2-14 Step 8: Soil Exposure Depth Selection ................................................. 2-14 Step 9: Final ESL Determination Process ............................................. 2-15 Step 10: Compare Site Data to ESLs.................................................... 2-15 Step 11: Compare Site Data to Background/Ambient Levels ................ 2-19 Step 12: Evaluate the Need for Additional Investigation, Assessment, or Remediation.................................................................... 2-19 Example of Interactive Tool Use: Dry Cleaner Release of Tetrachloroethene and Stoddard Solvent ........................ 2-19

2.5 Tier 3 – Modifications to Tier 2 Screening Levels, Screening Level Development for Different Exposure Scenarios, or Quantitative Risk Assessments ........................................................................................ 2-20 3 METHODS: DIRECT EXPOSURE HUMAN HEALTH RISK SCREENING
LEVELS FOR ALL MEDIA.................................................................... 3-1

3.1 Groundwater Direct Exposure ESLs .......................................................3-2

3.1.1 Direct Exposure Health Risk Criteria ........................................3-2

3.1.2 Hierarchy for Direct Exposure Health Risk Criteria ...................3-3

3.2 Soil Direct Exposure ESLs......................................................................3-3

3.3 Indoor Air Direct Exposure ESLs ............................................................3-4

3.4 Calculation of Human Health Direct Exposure Screening Levels ............3-4

3.4.1 Background: Use of Screening Levels for Risk Assessment.....3-5

3.4.2 Exposure Scenarios: Land Use, Receptors, and Pathways ......3-7

3.4.3 Screening Level Equations.......................................................3-8

3.4.4 Inputs: Target Cancer Risk and Noncancer Hazard..................3-8

3.4.5 Inputs: Physical/Chemical Constants........................................3-8

3.4.6 Inputs: Toxicity Values..............................................................3-8

3.4.7 Inputs: Exposure Factors........................................................ 3-11

3.4.8 Exception: Soil Noncancer Screening Levels for Lead............ 3-16

3.5 Addressing Cumulative Risk and Hazard.............................................. 3-16

3.5.1 Workbook Tier 2 Risk and Hazard Calculator......................... 3-18

3.6 Exceptions: Human Health Screening Levels for Chemical Mixtures .... 3-18

3.6.1 Background: Assessing Health Risks from Chemical Mixtures .. 3- 18 43.649
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3.6.2 Chlordane............................................................................... 3-20

3.6.3 DDD, DDE, and DDT.............................................................. 3-21

3.6.4 Dioxins and Furans ................................................................ 3-21

3.6.5 Endosulfan ............................................................................. 3-22

3.6.6 Polychlorinated Biphenyls (PCBs).......................................... 3-23

3.6.7 Polycyclic Aromatic Hydrocarbons (PAHs) ............................. 3-23

3.6.8 Petroleum Mixtures ................................................................ 3-26

3.7 Site-Specific Evaluations ...................................................................... 3-26 4 METHODS: PETROLEUM MIXTURE SCREENING LEVELS ................... 4-1

4.1 Background ............................................................................................4-2

4.1.1 Petroleum Chemistry................................................................4-2

4.1.2 Environmental Fate of Released Petroleum .............................4-4

4.1.3 Petroleum Hydrocarbon Oxidation Products (HOPs)................4-5

4.2 Approach to Evaluating Human Health Risks Posed by Petroleum Releases.................................................................................................4-6

4.2.1 Risk Assessment Challenges for Petroleum Releases .............4-6

4.2.2 Individual Chemicals ................................................................4-7

4.2.3 Petroleum Hydrocarbon Fractions .......................................... 4-10

4.2.4 Petroleum Hydrocarbon Oxidation Products (HOPs).............. 4-13

4.2.5 Selecting Chemicals of Potential Concern for Petroleum Releases......................................................................... 4-14

4.3 Calculation of ESLs for Petroleum Hydrocarbon Mixtures..................... 4-14

4.3.1 Petroleum Fraction Compositions for Each Petroleum Mixture Based on Medium ........................................................... 4-15

4.3.2 Petroleum Fraction Toxicity and Physical-Chemical Values.... 4-16

4.3.3 Petroleum Mixture Toxicity Values and Henry’s Law Constants 4- 17 4.3.4 Screening Levels for Other Mixtures....................................... 4-18

4.3.5 Lack of ESLs for Crude Oils and Bunker Fuels....................... 4-18

4.3.6 Summary................................................................................ 4-18

4.4 Calculation of Groundwater ESLs for Petroleum HOPs......................... 4-19

4.4.1 Petroleum HOPs Toxicity and Physical-Chemical Values....... 4-19

4.4.2 Summary................................................................................ 4-21

4.5 Laboratory Analytical Methods for Use with the Petroleum Mixture ESLs 4- 21 43.650
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4.5.1 Background: Bulk TPH Laboratory Method (USEPA Method 8015B) ............................................................................ 4-21

4.5.2 Measuring Hydrocarbons using the Bulk TPH Analytical Method ........................................................................................ 4-26

4.5.3 Measuring HOPs using the Bulk Extractable TPH Method ..... 4-26

4.5.4 Determining Background Levels of Natural Organic Compounds (NOCs)............................................................................ 4-29

4.5.5 Recommended Bulk TPH Analyses for Soil and Groundwater Samples.......................................................................... 4-30

4.5.6 Recommendations for Vapor Analyses................................... 4-31

4.6 Site-Specific Human Health Risk Evaluations for Petroleum Mixtures... 4-32

4.6.1 Screening Level Evaluations Using the Petroleum Mixture ESLs ........................................................................................ 4-32

4.6.2 Site-Specific Human Health Risk Evaluations of Petroleum Hydrocarbons: TPH Fractionation Methods..................... 4-33 5 METHODS: VAPOR INTRUSION RISK SCREENING LEVELS FOR
GROUNDWATER AND SUBSLAB/SOIL GAS ....................................... 5-1

5.1 Background ............................................................................................5-1

5.1.1 Conceptual Model for Vapor Intrusion into Buildings ................5-1

5.1.2 Multiple Lines of Evidence (MLE) Approach to Evaluating Vapor Intrusion ............................................................................5-5

5.1.3 Lack of VI ESLs for Soil............................................................5-6

5.1.4 Lack of VI ESLs for Crawl Space Air ........................................5-7

5.1.5 Lack of VI ESLs for Sewer/Utility Conduit Air............................5-7

5.2 Calculation of Soil Gas and Groundwater VI ESLs..................................5-7

5.2.1 Vapor Attenuation Factors........................................................5-7

5.2.2 Soil Gas VI ESLs.................................................................... 5-10

5.2.3 Groundwater VI ESLs............................................................. 5-11

5.3 Chemical-Specific Exceptions............................................................... 5-11

5.4 Site-Specific Evaluations ...................................................................... 5-11

5.4.1 Vapor Conduit Pathway Evaluations: Sewer/Utility Conduit Air.. 5- 12 5.4.2 Estimating Site-Specific Attenuation Factors: Vapor Intrusion Models ............................................................................ 5-13

5.4.3 Petroleum Vapor Intrusion (PVI)............................................. 5-15

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6 METHODS: SHORT-TERM ACTION LEVELS FOR TCE IN ALL MEDIA .. 6-1

6.1 Background on TCE Noncancer Effects..................................................6-1

6.2 Short-Term Action Levels, Response Times and Response Actions for TCE Exposure in Indoor Air ....................................................................6-1

6.3 Action Levels and Response Actions for TCE Vapor Intrusion from Groundwater and Soil Gas......................................................................6-3

6.4 Potential for Rapid Response Due to TCE Exposure Via Ingestion.........6-3 7 METHODS: AQUATIC HABITAT SCREENING LEVELS FOR
GROUNDWATER ................................................................................ 7-1

7.1 Aquatic Receptor Toxicity Criteria...........................................................7-2

7.2 Hierarchy for Aquatic Receptor Toxicity Criteria......................................7-3

7.3 Chemical-Specific Exceptions.................................................................7-4

7.3.1 Barium......................................................................................7-4

7.3.2 Methyl Tertiary Butyl Ether (MTBE) ..........................................7-5

7.3.3 Petroleum Mixtures ..................................................................7-5

7.3.4 Selenium ..................................................................................7-6

7.3.5 Tertiary Butyl Alcohol (TBA) .....................................................7-7

7.3.6 1,2,3-Trichloropropane .............................................................7-7

7.4 Site-Specific Evaluations ........................................................................7-7

7.4.1 Groundwater Discharge Evaluation ..........................................7-7

7.4.2 Site-Specific Aquatic Toxicity Testing .......................................7-9

7.4.3 Fate and Transport Modeling.................................................. 7-10

7.4.4 Additional Considerations for Site-Specific Evaluations.......... 7-11 8 METHODS: TERRESTRIAL HABITAT SCREENING LEVELS FOR SOIL . 8-1

8.1 Background and Basis for Screening Levels...........................................8-1

8.1.1 Background on Ontario Ministry of the Environment (MOE) Screening Levels...............................................................8-1

8.1.2 Development of Terrestrial Habitat ESLs..................................8-3

8.2 Exceptions ..............................................................................................8-4

8.3 Site-Specific Evaluations ........................................................................8-4 9 METHODS: LEACHING TO GROUNDWATER SCREENING LEVELS FOR SOIL.................................................................................................. 9-1

9.1 Leaching Model ......................................................................................9-1

9.1.1 Conceptual Model ....................................................................9-1

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9.1.2 Generic Dilution-Attenuation Factor (DAF) Equation ................9-3

9.2 Calculation of Soil Leaching Screening Levels........................................9-4

9.2.1 Chemicals with Low to Moderate Soil Sorptivity........................9-4

9.2.2 Chemicals with High Soil Sorptivity...........................................9-4

9.3 Exceptions ..............................................................................................9-5

9.3.1 Metals ......................................................................................9-5

9.3.2 Polychlorinated Biphenyls (PCBs)............................................9-5

9.3.3 Perchlorate...............................................................................9-5

9.4 Site-Specific Evaluations ........................................................................9-6

9.4.1 Calculate Leaching Screening Level for a Specific Groundwater Target Level ......................................................................9-7

9.4.2 Calculating Site Specific DAFs .................................................9-7

9.4.3 Groundwater Testing................................................................9-7

9.4.4 Leachability Testing..................................................................9-8

9.4.5 Evaluating Saturated Soils .......................................................9-8 10 METHODS: GROSS CONTAMINATION SCREENING LEVELS FOR
GROUNDWATER AND SOIL ............................................................. 10-1

10.1 Calculation of Gross Contamination Screening Levels..........................10-1

10.1.1 Groundwater ..........................................................................10-1

10.1.2 Soil 10-1

10.2 Exceptions ............................................................................................10-2

10.3 Site-Specific Evaluations ......................................................................10-2 11 METHODS: TASTE AND ODOR NUISANCE SCREENING LEVELS FOR ALL MEDIA............................................................................................. 11-1

11.1 Background ..........................................................................................11-1

11.2 Groundwater Taste and Odor Nuisance Thresholds .............................11-2

11.2.1 Sources of Taste and Odor Threshold Values ........................11-2

11.2.2 Hierarchy for Taste and Odor Nuisance Thresholds ...............11-3

11.3 Soil Odor Nuisance Thresholds ............................................................11-4

11.4 Indoor Air and Soil Gas Odor Nuisance Thresholds..............................11-5

11.5 Exceptions ............................................................................................ 11-6

11.6 Site-Specific Evaluations ......................................................................11-6

11.6.1 Field Investigations of Potential Nuisance Odor Condition......11-6

11.6.2 Attenuation of Petroleum Vapors and Odors ..........................11-7

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12 ADDITIONAL CONSIDERATIONS .................................................... 12-1

12.1 Multiple Chemical Species....................................................................12-1

12.1.1 Cyanide..................................................................................12-1

12.1.2 Chromium...............................................................................12-1

12.2 Chemicals Without ESLs ......................................................................12-2

12.3 Chemical Degradation and Generation of Transformation Products......12-2

12.4 Naturally Occurring Background and Ambient Chemicals .....................12-3

12.4.1 Example: Naturally Occurring Arsenic ....................................12-4

12.4.2 Example: Anthropogenic Polycyclic Aromatic Hydrocarbons ..12-5

12.5 Sediment Screening Levels ..................................................................12-5

12.6 Laboratory Data Issues.........................................................................12-7

12.6.1 Detection Limits and Reporting Limits ....................................12-7

12.6.2 Soil Data Reporting: Dry Weight Basis ...................................12-7

12.7 Acute Hazards ......................................................................................12-8

12.7.1 Methane .................................................................................12-8

12.7.2 Explosion Hazards ................................................................. 12-9

12.8 Total Maximum Daily Loads (TMDLs)...................................................12-9 13 REFERENCES................................................................................... 13-1 14 ACRONYMS AND ABBREVIATIONS ................................................. 14-1 15 APPENDIX A – EQUATIONS FOR DIRECT EXPOSURE SCREENING LEVELS............................................................................................ 15-1

15.1 Noncarcinogenic Risk-Based Screening Levels....................................15-2

15.1.1 Ingestion Noncarcinogenic Risk-Based Screening Levels ......15-2

15.1.2 Inhalation Noncarcinogenic Risk-Based Screening Levels .....15-2

15.1.3 Dermal Noncarcinogenic Risk Based Screening Levels .........15-3

15.2 Carcinogenic Risk based Screening Levels ..........................................15-4

15.2.1 Ingestion Carcinogenic Risk-Based Screening Levels ............15-4

15.2.2 Inhalation Carcinogenic Risk-Based Screening Levels ...........15-5

15.2.3 Dermal Carcinogenic Risk-Based Goals................................. 15-5

15.3 Total Cancer or Noncancer Screening Levels for All Exposure Pathways 15-6
16 APPENDIX B – CHECKLIST FOR VAPOR INSTRUSION MODELS...... 16-1

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Figures
Figure 2-1 – Tiered Process for Selecting Screening Levels............................. 2-1 Figure 2-2 – Example Illustrating Horizontal Extent of Tetrachloroethene in Shallow Groundwater.................................................................... 2-4 Figure 2-3 – Example Cross Section Illustrating Contaminant Distribution........ 2-5 Figure 2-4 – Default Evaluation of Receptors and Exposure Pathways Used in a Tier 1 Assessment......................................................................... 2-6 Figure 2-5 – Example of a Site-Specific Evaluation of Receptors and Exposure Pathways....................................................................................... 2-7 Figure 2-6 – Final Site-Specific Groundwater ESL Determination................... 2-16 Figure 2-7 – Final Site-Specific Soil ESL Determination.................................. 2-17 Figure 2-8 – Final Site-Specific Subslab/ Soil Gas ESL Determination ........... 2-18 Figure 2-9 – Final Site-Specific Indoor Air ESL Determination ........................ 2-18 Figure 2-10 – ESL Workbook Interactive Tool Tier 2 ESL Input and Output Table T2-1 for Example Scenario.......................................................... 2-21 Figure 2-11 – Interactive ESL Workbook Tool Table T2-2 for the Example Scenario ...................................................................................... 2-22 Figure 2-12 – Interactive ESL Workbook Tool Specific Concerns Table T2-3 for the Example Scenario ................................................................. 2-23 Figure 4-1 – Diagram Illustrating the Petroleum Fractions in the ESLs by Equivalent Carbon Number (after USEPA 2009c)....................... 4-12 Figure 4-2 – Example of Basic Petroleum Chromatogram Review for HOPs. . 4-25 Figure 4-3 – Conceptual Plume Map Showing How to Estimate Petroleum HOPs Concentrations ............................................................................ 4-27 Figure 4-4 – Illustration of the Key Shortcoming with the TPH-diesel (also “dieselrange organics” or “DRO”) Analysis for Measuring Petroleum HOPs Concentrations. ........................................................................... 4-29 Figure 4-5 – Example Carbon Ranges for Bulk TPH and TPH Fractionation Laboratory Analyses.................................................................... 4-35 Figure 5-1 – Conventional Conceptual Model for Vapor Intrusion ..................... 5-3 Figure 5-2 – Slab Capping Effect and Soil Gas Sampling Locations Best Representing Concentrations in Contact with a Building Foundation ...................................................................................................... 5-4 Figure 5-3 – Conceptual Model for the Sewer Air Vapor Intrusion Pathway...... 5-5

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Figure 5-4 – Conceptual Model for the Development of a Site-Specific Vapor Intrusion Attenuation Factor (AF) ................................................ 5-14 Figure 5-5 – Conceptual Model for the Petroleum Vapor Intrusion Pathway Illustrating When the Pathway is Incomplete and Potentially Complete..................................................................................... 5-16 Figure 5-6 – Typical Vertical Profiles for Concentrations of Petroleum Hydrocarbons (PHCs), Oxygen, Carbon Dioxide and Methane in the Vadose Zone............................................................................... 5-18 Figure 7-1 – Bay Margin Groundwater Discharge Conceptual Model................ 7-2 Figure 9-1 – Conceptual Model for Soil Leaching ESLs .................................... 9-2 Tables
Table of Concerns Addressed by ESLs................................................................. i Table 1-1 – Environmental Concerns Stated or Implied in the Basin Plan and Addressed by ESLs ........................................................................................... 1-3 Table 1-2 – Environmental Concerns for ESLs versus Other Screening Levels 1-8 Table 1-3 – Low-Threat UST Case Closure Policy (LTCP) General Criteria ... 1-12 Table 1-4 – Regional Water Board Closure Criteria for Non-UST Sites .......... 1-13 Table 1-5 – Technical Resource Documents for Use with the ESLs ............... 1-14 Table 2-1 – Information for a Conceptual Site Model ........................................ 2-2 Table 2-2 – Tier 1 ESL Conceptual Site Model................................................ 2-10 Table 3-1 ‒ Human Health Direct Exposure Scenarios in the ESLs.................. 3-1 Table 3-2 – Soil Human Health Direct Exposure Scenarios .............................. 3-4 Table 3-3 – Human Health Toxicity Value Hierarchy......................................... 3-9 Table 3-4 – Exposure Factor Selection ........................................................... 3-13 Table 3-5 – Mutagens 1 ................................................................................... 3-15 Table 3-6 – World Health Organization Toxic Equivalency Factors for Dioxins and Furans (2005).................................................................................................. 3-22 Table 3-7 – PAHs in the ESLs and Relative Potency Factors for the Carcinogenic PAHs ............................................................................................................... 3-24 Table 4-1 – Physical-Chemical Properties of Selected Hydrocarbons and Hydrocarbon Oxidation Products....................................................................... 4-3

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Table 4-2 – Potential Individual Chemicals of Concern for Different Petroleum Mixtures............................................................................................................. 4-9 Table 4-3 – ESL Petroleum Hydrocarbon Fractions and Partitioning Characteristics................................................................................................. 4-13 Table 4-4 – Chemicals of Potential Concern for Petroleum Risk Evaluations . 4-14 Table 4-5 – Bulk TPH Laboratory Analysis for Soil and Groundwater Samples .. 4- 31 Table 7-1 – Hierarchy for Aquatic Receptor Toxicity Criteria............................. 7-3 Table 11-1 – Hierarchy of Taste and Odor Thresholds for Groundwater.........11-4 Table 11-2 – Criteria for Assignment of Odor Upper Limit Levels for Soil .......11-5 Table 12-1 – Publications Regarding Naturally Occurring Background Levels 12-4 Table 12-2 –Sediment Chemical Criteria or Relevant Guidance .....................12-6

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1 Introduction and Background
The Environmental Screening Levels (ESLs) are groundwater, soil, soil gas, and indoor air concentrations derived by San Francisco Bay Regional Water Quality Control Board (Regional Water Board) staff for over 100 chemicals to allow direct comparison to environmental sample data collected at contaminated sites. The ESLs consist of the following:

1. Cover Memo;

2. ESL Workbook (Microsoft Excel Workbook) and Summary ESL Tables (PDF);

3. User’s Guide; and

4. Frequently Asked Questions (FAQs)
The following sections provide regulatory basis for the ESLs, history and use, comparison to other screening levels, the Regional Water Board’s approach to site closure evaluations, and other technical documents for use in conjunction with the ESLs.

1.1 San Francisco Bay Basin Water Quality Control Plan
(Basin Plan)
The ESLs were ultimately developed to help the Regional Water Board staff protect water quality in the Region. By law, the Regional Water Board is required to develop, adopt (after public hearing), and implement a Water Quality Control Plan (Basin Plan) for the region (San Francisco Bay Region). The Basin Plan (Regional Water Board 2017b) is the master policy document that contains descriptions of the legal, technical, and programmatic bases of water quality regulation in the region. The plan includes:
• A statement of beneficial water uses to be protected; • The water quality objectives needed to protect the designated beneficial water uses; and
• The strategies and time schedules for achieving the water quality objectives.

The San Francisco Bay Region is 4,603 square miles, roughly the size of the State of Connecticut, and characterized by its dominant feature, 1,100 square miles of the 1,600 square mile San Francisco Bay Estuary (Estuary). The Estuary is the largest on the west coast of the United States, where fresh waters from California’s Central Valley mix with the saline waters of the Pacific Ocean (Regional Water Board 2017b).

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Because of its highly dynamic and complex environmental conditions, the Bay supports an extraordinarily diverse and productive ecosystem. Within each section of the Bay, there are deep water areas adjacent to large expanses of very shallow water. Salinity levels range from hypersaline to fresh water, and water temperature varies throughout the Bay system. These factors greatly increase the number of species that can live in the Estuary and enhance its biological stability.

Groundwater is an important component of the hydrologic system in the Region.

Groundwater provides excellent natural storage, distribution, and treatment systems. Groundwater also supplies high quality water for drinking, irrigation, and industrial processing and service. As an important source of freshwater replenishment, groundwater may also discharge to surface streams, wetlands, and San Francisco Bay. A variety of historical and ongoing industrial, urban, and agricultural activities and their associated discharges have degraded groundwater quality. Adverse impacts on groundwater quality often have long‐ term effects that are costly to remediate. Consequently, as new additional discharges are identified, investigation, source control, pollution containment, and cleanup must be undertaken as quickly as possible. Activities that may potentially pollute groundwater must be managed to ensure the short- and longterm protection of groundwater quality.

The following sections introduce certain components of the Basin Plan that guide the creation of the ESLs, including the beneficial uses of surface water and groundwater, the environmental concerns in the Basin Plan, and the overarching approach to site investigation and cleanup presented in the Basin Plan for the various cleanup programs.

1.1.1 Beneficial Uses of Surface Water and Groundwater
State policy for water quality control in California is directed toward achieving the highest water quality consistent with maximum benefit to the people of the State.

Aquatic ecosystems and underground aquifers provide many direct and indirect different benefits. Beneficial uses define the resources, services, and qualities of the aquatic systems that should be protected by the Regional Water Board from pollution and nuisance conditions following unpermitted waste discharges in the region. Beneficial uses of waters of the State serve as a basis for establishing water quality objectives and discharge prohibitions to protect water quality.

The beneficial uses drive two key water quality considerations in the ESLs:

1. All Groundwater is Considered Suitable or Potentially Suitable for Municipal or Domestic Water Supply unless Designated Otherwise by the Regional Water Board – All groundwater in the Region is considered a potential source of drinking water unless demonstrated otherwise. The Basin Plan recognizes that site-specific factors, such as low yield or poor water quality, may render groundwater unsuitable as a

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potential drinking water source (“non-potable” groundwater). These factors are described in State Water Resources Control Board (State Water Board) Resolution No. 88-63, Adoption of Policy Entitled “Sources of Drinking Water” (State Water Board 1988). In the ESL Workbook, the Tier 2 ESLs include a toggle allowing the users to determine alternate screening criteria in these situations. A conclusion that groundwater is “non-potable” at a particular site must be based on site-specific data and must be approved by the overseeing regulatory agency. A conclusion that groundwater is non-potable does not mean other concerns can be ignored (e.g., vapor intrusion, groundwater discharge to surface water, nuisance odor).

2. All Groundwater is Assumed to Ultimately Discharge to Surface Water and Potentially Affect Aquatic Organisms and Habitats – This assumption can be overly conservative for sites far from surface water bodies and where the extent of groundwater contamination is defined and is demonstrated to be stable (e.g., not migrating). Chapter 7 provides information regarding options for site-specific evaluations. A conclusion that groundwater does not discharge to surface water should be based on site-specific data or information accepted by the overseeing regulatory agency. Although modeling can assist with evaluating this pathway, it should not be used exclusively to conclude whether groundwater will discharge to surface water.

Soil and groundwater ESLs have therefore been developed to protect both drinking water resources and aquatic habitats.

1.1.2 Environmental Concerns in the Basin Plan
Each ESL addresses the environmental concerns stated or implied in the Basin Plan. These concerns are presented in Table 1-1.

Table 1-1 – Environmental Concerns Stated or Implied in the Basin Plan and Addressed by ESLs
Medium Human
Health
Drinking
Water
Resource
Aquatic
Receptors
(Discharge
to Surface
Water)
Terrestrial
Receptors
(Direct
Contact)
Source
Control
Nuisance
Taste
and Odor
Groundwater
Yes Yes Yes -- Yes Yes
Soil/
Soil Gas
Yes Yes Yes Yes Yes Yes
Indoor
Air Yes -- -- -- -- Yes

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1.1.3 Investigation and Cleanup of Discharges
State Water Board Resolution No. 92-49, Policies and Procedures for Investigation, Cleanup and Abatement of Discharges Under Water Code Section 13304 (Resolution 92-49; State Water Board 1992) contains the policies and procedures for all Water Boards to follow when overseeing and regulating investigations and cleanup and abatement activities resulting from all types of discharges or threat of discharge subject to Water Code section 13304.

Resolution 92-49 outlines the basic elements of site investigations and cleanup of discharges. The five basic components of site investigation are:

1. Preliminary site assessment to confirm the discharge/ identify the discharger; identify affected or threatened waters of the State and their beneficial uses; and develop preliminary information on the nature and horizontal and vertical extent of the discharge;

2. Soil and water investigation to determine the source, nature, and extent of the discharge with sufficient detail to provide the basis for decisions regarding subsequent cleanup, if any are determined by the Regional Water Board as necessary;

3. Proposal and selection of cleanup action to evaluate feasible and effective cleanup and abatement actions and to develop preferred cleanup and abatement alternatives;

4. Implementation of cleanup and abatement action to implement the selected alternative and to monitor in order to verify progress; and

5. Monitoring to confirm short- and long-term effectiveness of cleanup and abatement.

Minimum cleanup and abatement methods include:
• Source removal and/or isolation;
• In-place treatment of soil or water, including bioremediation, aeration, and fixation;
• Excavation or extraction of soil, water, or gas for on-site or off-site treatment techniques including bioremediation; thermal destruction; aeration; sorption; precipitation, flocculation and sedimentation; filtration; fixation; and evaporation; and,
• Excavation or extraction of soil, water, or gas for appropriate recycling, reuse, or disposal.

In addition, the Basin Plan recognizes a deed restriction (land use covenant), which typically incorporates a risk management plan, may be required to facilitate the remediation of past environmental contamination and to protect human health and the environment by reducing the risk of exposure to residual hazardous materials. Water Code section 13307.1 requires deed restrictions for certain sites

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not cleaned up to allow “unrestricted use.” Furthermore, deed restrictions must be recorded and “run” with the land.

1.2 History of the ESLs
The San Francisco Bay Regional Water Board Control Board first published riskbased screening levels (RBSLs) in September 2000. Screening levels were developed for 100 commonly encountered chemicals at sites with impacted soil and groundwater. The RBSLs were intended to expedite risk assessments and evaluations of the need for additional work, particularly for small- to mediumsized sites. Following peer review of the 2001 RBSLs by the University of California, the scope was broadened beyond human health risk to include ecological risk (aquatic and terrestrial receptors), concerns for nuisance and potential presence of separate-phase liquid (gross contamination). This effort culminated in 2003 with the renamed Environmental Screening Levels (ESLs) that added screening levels for surface water, indoor air, and soil gas. Regional Water Board staff continues to maintain and update the ESLs, with updates generally about every two to three years. After first publication, major updates have been published as follows: December 2001; July 2003; February 2005; May 2008; 2013 (February and December); and February 2016 (three revisions).

1.3 Intended Use of the ESLs
The ESLs are intended as a tool to screen or evaluate the chemical threats posed by contamination at a site.

Sites that are adequately characterized with chemical concentration data below the ESLs most likely do not pose a chemical threat. In some rare instances, there could be an exception resulting from cumulative risk where a large number of chemicals are present at a site, but individual chemical concentrations are just below the respective ESL (evaluation of cumulative risk is discussed in Chapter 3). For a site where chemical concentrations exceed the ESLs, the site may pose a chemical threat and require further investigation or evaluation to better assess the threat. The ESLs do not address hazards such as asphyxiation or explosions.

The ESLs are intended to be conservative, but reasonable.

The main purpose of screening levels is to quickly enable users to distinguish which sites pose a significant threat. In developing screening levels, there must be a balance between conservativeness and reasonableness so that low risk sites are screened out and sites with a significant threat are screened in and given greater attention. When developing screening levels from models, such as those used for human health risk criteria, if the most conservative value is used

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for every input parameter, the resulting screening level may be overly conservative. This approach can cause sites that pose no significant threat to be screened in, requiring the expenditure of resources (time and money) by all stakeholders (regulatory, discharger, and others) to further assess the contamination. This approach is inefficient and problematic because it diverts resources from sites with significant threats.

The ESLs are a communication tool amongst the various stakeholders.

Screening levels help dischargers, technical consultants, and other stakeholders understand Regional Water Board staff expectations and approaches to evaluating contaminated sites. The ESLs are not default cleanup goals. Cleanup goals typically are chemical concentrations for a specific site that are agreedupon through a risk and feasibility evaluation and discussions between the overseeing regulatory agency and the discharger considering site-specific conditions. For many sites, ESLs are selected as cleanup goals, but only after going through the process of evaluation and adoption. The Regional Water Board typically accepts ESLs as preliminary cleanup goals.

The ESLs save time and money.

Preparation of quantitative environmental risk assessments for multiple pathways at contaminated sites requires a greater level of expertise and frequently requires a multi-disciplinary team (toxicologists or risk assessors, chemists, engineers, environmental scientists, and geologists). The costs to prepare a comprehensive risk assessment can be substantial, and potentially prohibitive, for small businesses and property owners with limited financial resources. A “Tier 2” risk evaluation can be developed relatively quickly with the ESLs.

The ESLs are a prioritization tool.

Regional Water Board staff is required to prioritize the oversight of cases to maximize our protection of human health and the environment. The ESLs serve as an aid in assessing the overall threat (pathways and threat level) at any given site, allowing us to understand whether threats to human health or the environment are adequately controlled. We can then prioritize the investigation and cleanup needed to eliminate or control the threats posed by the contamination at a site.

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1.4 Comparison of ESLs to Other Screening Levels and
Criteria

1.4.1 Other Screening Levels
The ESLs address a greater range of media and concerns than other commonlyused screening levels and reflect the broader scope of environmental concerns outlined in the Basin Plan (Table 1-2).

USEPA RSLs/VISLs
The United States Environmental Protection Agency (USEPA) publishes Regional Screening Levels (RSLs; formerly known as Preliminary Remediation Goals or PRGs; USEPA 2018b) about twice per year. The RSLs include generic tables of criteria and an online calculator that address human health concerns associated with direct exposure to chemicals. The direct exposure ESLs are calculated using the standard equations used for the RSLs. However, some toxicity values and exposure factors inputs are different (see Chapter 3). Unlike the ESLs, RSLs do not address ecological, gross contamination, or odor nuisance concerns. The USEPA also has a Vapor Intrusion Screening Level calculator (VISL; USEPA 2018a) that calculates groundwater and soil gas (subslab and deeper or exterior soil gas) vapor intrusion screening levels using USEPA default attenuation factors (USEPA 2015a).

CalEPA CHHSLs
In 2004 to 2005, the Office of Environmental Health Hazard Assessment (OEHHA) developed the California Human Health Screening Levels (CHHSLs) for more than 50 contaminants commonly detected in soil, soil gas, and indoor air. CHHSLs are set at an excess lifetime cancer risk of one-in-a-million, 10-6 and a hazard quotient of 1.0 for noncancer hazard (CalEPA 2005). The basis of derivation is presented in Human-Exposure-Based Screening Numbers Developed to Aid Estimation of Cleanup Costs for Contaminated Soil (OEHHA 2004a). The CHHSLs do not address potential groundwater or surface water protection concerns and focus on only a portion of the human health concerns addressed by the ESLs.

The CHHSLs should not be used as a stand-alone tool to evaluate contaminated sites because the CHHSLs do not cover the full scope of potential environmental concerns. It is important to understand that for many chemicals, the need for remedial action may be based on environmental concerns and not direct exposures.

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Table 1-2 – Environmental Concerns for ESLs versus Other Screening Levels
Media Environmental Concern ESLs
USEPA
RSLs and
VISLs
CalEPA
CHHSLs
Groundwater Direct Exposure (Ingestion,
Inhalation, Dermal) Yes Yes/RSLs Yes
Groundwater Vapor Intrusion
(Direct Exposure: Inhalation) Yes Yes/VISLs --
Groundwater Discharge to Surface Water
(Aquatic Receptors) Yes -- --
Groundwater Gross Contamination Yes -- --
Groundwater Taste and Odor Nuisance Yes -- --
Soil Direct Exposure (Ingestion,
Inhalation, Dermal) Yes Yes/RSLs Yes
Soil Terrestrial Habitat Yes -- --
Soil Leaching to Groundwater Yes Yes/RSLs --
Soil Gross Contamination Yes -- --
Soil Odor Nuisance Yes -- --
Soil Gas Vapor Intrusion
(Direct Exposure: Inhalation) Yes Yes/VISLs Yes
Soil Gas Odor Nuisance Yes -- --
Indoor Air Direct Exposure
(Inhalation) Yes Yes/RSLs and VISLs Yes
Indoor Air Odor Nuisance Yes -- --
DTSC-Modified Screening Levels
The California Department of Toxic Substances Control (DTSC) endorses the RSL soil, tapwater, and air values for chemicals listed in the RSLs except where California toxicity criteria values are required per the Toxicity Criteria for Human Health Risk Assessments, Screening Levels, and Remediation Goal (“California Toxicity Criteria Rule”)1 or DTSC recommends more stringent criteria in Human Health Risk Assessment Note 10 (DTSC 2019a). For chemicals meeting these

1 DTSC website for the California Toxicity Criteria Rule:
https://www.dtsc.ca.gov/LawsRegsPolicies/Regs/Toxicity-Criteria-for-HumanHealth-Risk-Assessment.cfm

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exceptions, DTSC publishes DTSC-modified screening levels (DTSC-SLs) in Human Health Risk Assessment Note 3 (DTSC 2019c) for soil, tapwater, and air, as needed. Human Health Risk Assessment Note 3 is updated twice per year.

1.4.2 Hazardous Waste Regulations and OSHA Standards
The ESLs are not criteria to be used for determining how or where to dispose of waste soils or waters. California Code of Regulations Title 22, Section 66699 (Persistent and Bioaccumulative Toxic Waste) includes criteria that are used for classifying waste material for disposal in a Class I, II, or III landfill. These are the California Total Threshold Limit Concentrations (TTLC) criteria and Soluble Threshold Limit Concentration (STLC) criteria, which are used to compare laboratory analytical data from solid waste materials and solid waste materials subjected to the California Waste Extraction Test, respectively.

These waste profiling criteria should not, in most cases, be used to screen or evaluate soil and groundwater data or to set cleanup goals. The criteria, developed in the 1980s, are only loosely based on human health and environmental considerations. Rather, these criteria define safe waste concentrations for placement in a landfill where low pH conditions may increase mobilization of metals and other constituents. STLC values generally reflect drinking water or surface water goals of the time. TTLC values were derived by simply multiplying the STLC value by 10 for organic chemicals or 100 for metals.

It is unlikely that the TTLC and STLC values will be revised in the near future. In most cases, TTLC values exceed the most conservative ESLs. However, in certain instances TTLC values may be lower than risk-based ESLs.

1.4.3 OSHA Standards: Permissible Exposure Limits
The National Institute for Occupational Safety and Health (NIOSH) is the Federal agency responsible for conducting research and making recommendations for the prevention of work-related disease and injury, including exposure to hazardous chemicals in air (NIOSH 2007). NIOSH develops and periodically revises Recommended Exposure Limits (RELs) for hazardous substances in the workplace. The RELs are used to promulgate Permissible Exposure Limits (PELs) under the Occupational Safety and Health Act (OSHA).

OSHA PELs are derived for an occupational setting, where the:

1. Chemical in question is used in the industrial process;

2. Workers and others who might be exposed to the chemical have knowledge of the chemical's presence;

3. Workers receive appropriate health and safety training; and,

4. Workers may be provided with protective gear to minimize exposures.

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The OSHA PELs are derived for adult, healthy workers and are not intended to protect children, pregnant women, the elderly, or people with compromised immune systems. OSHA recognizes that many of its PELs are outdated and inadequate for ensuring protection of worker health and is presently evaluating how to update them (United States Department of Labor – Occupational Safety & Health Administration 2016).

The question of applicability OSHA PELs versus ESLs typically arises when the results of indoor air sampling indicate the presence of the same VOCs detected in groundwater, soil, or soil gas at or near the site. In such a situation, whether worker safety criteria or ESLs are applicable depends on the source of the VOCs detected in indoor air. If the source is clearly from the business operation, the appropriate worker safety criteria apply. If the source is the subsurface contamination, the ESLs apply. Distinguishing between sources can be challenging, but there are various techniques that can be employed (e.g., comparison of chemical ratios in subsurface and indoor air samples, compound-specific isotopes, use of portable instruments such as gas chromatographs with mass spectrometry detector GC-MS, and continuous analyzers that are in development). More information on these techniques and references are presented in the Interim Framework for Assessment of Vapor Intrusion at TCE-Contaminated Sites in the San Francisco Bay Region (TCE Framework; Regional Water Board 2014).

DTSC and USEPA have taken similar positions on the use of PELs. The DTSC Vapor Intrusion Guidance (VIG; DTSC 2011b) indicates Occupational Safety and Health Act (OSHA) PELs are inappropriate exposure endpoints in work-related occupational settings for indoor air degraded by subsurface contamination and includes a detailed discussion of the use of the PELs (VIG Appendix C). USEPA (2015a) also does not recommend use of the PELs for purposes of assessing human health risk posed to workers.

Other aspects pertinent to the applicability of the PELs for a specific site include:
• OSHA PELs are not appropriate for health risk evaluations for commercial settings where the chemical is not currently being used as part of a regulated, industrial process. This includes sites affected by the migration of offsite releases.
• According to State Water Resources Control Board Resolution No. 92-49, Policies and Procedures for Investigation and Cleanup and Abatement of Discharges under Water Code Section 13304, the Regional Water Boards must set cleanup goals that protect the full range of people who might be exposed to contaminants in soil and groundwater, including sensitive receptors. This goes beyond adult, healthy workers for which the OSHA limits are intended. OSHA limits are not intended to evaluate risks posed by involuntary exposures to the general public, where site residents and occupants generally do not expect to be exposed to chemicals from a vapor intrusion pathway, do not receive training on such exposure, and have no protective gear to minimize exposures. USEPA Region 9 (USEPA

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2014b) has developed accelerated response action levels (ARALs) and urgent response action levels (URALs) for trichloroethene (TCE) in indoor air for the protection of women of child-bearing age in residential and commercial settings. Based on the acute nature of the potential effects of exposure to TCE actions should be taken to reduce exposure to TCE exceeding the ARALs or URALs in weeks or days. This is discussed further in Chapter 6.

1.5 Site Closure Evaluations: Use of the ESLs
While the protection of public health, safety, and the environment is our top priority in the Regional Water Board’s site cleanup programs, moving sites towards and achieving regulatory site closure (i.e., No Further Action or NFA) is fundamentally important, as well. The ESLs are a tool to aid in evaluating cases eligible for closure. However, as previously stated, the ESLs are not default cleanup goals. Cleanup goals typically are chemical concentrations for a specific site that are agreed-upon through evaluation and discussions between the regulatory agency and discharger considering site-specific conditions. A discharger, for instance, may prefer to conduct a site-specific risk assessment to assist in developing cleanup goals. Similarly, a regulator may conclude that the ESLs do not address a key concern for a given site, such as backyard gardening, which requires a site-specific assessment.

Regional Water Board staff uses either of two approaches for evaluating sites for regulatory closure or No Further Action: The Low-Threat Underground Storage Tank Closure Policy (LTCP; State Water Board 2012b) or Closure Criteria for Non-UST Sites as discussed below.

1.5.1 Low-Threat Underground Storage Tank Case Closure
Policy
The main purpose of the LTCP is to improve the efficiency and consistency of the cleanup process for petroleum Underground Storage Tank (UST) sites. The LTCP facilitates closure for those UST sites that do not pose a threat to human health, the environment, or the waters of the State. Table 1-3 presents the eight general criteria that must be satisfied in order for a site to become eligible for low-threat closure.

The LTCP does not use the ESLs to screen contaminants at petroleumcontaminated sites. Instead the LTCP provides closure levels for carcinogens (benzene, ethylbenzene, methyl tertiary butyl ether or MTBE, naphthalene, and benzo[a]pyrene equivalents) and general (narrative) criteria (e.g., removal of the secondary source to the extent practicable). ESLs may be used at sites with “unique attributes” to screen for constituents not already addressed by the LTCP.

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The LTCP’s underlying CSM is that of a corner gasoline station where the sources of the petroleum release are the UST system. The LTCP includes two types of criteria: general (narrative) and media-specific. The three media-specific criteria include: 1) groundwater; 2) vapor intrusion; and 3) soil direct contact and outdoor air inhalation. The scientific rationale behind the criteria is presented in technical justification documents, now included in Appendix A of the Leaking Underground Fuel Tank Guidance Manual (State Water Board 2015).

Table 1-3 – Low-Threat UST Case Closure Policy (LTCP) General Criteria ID Narrative Criterion
a
The unauthorized release is located within the service area of a public water system
b The unauthorized release consists only of petroleum
c The unauthorized (“primary”) release from the UST system has been stopped
d Free product has been removed to the maximum extent practicable e A conceptual site model that assesses the nature, extent, and mobility of the release has been developed
f Secondary source has been removed to the extent practicable g Soil or groundwater has been tested for methyl tertiary butyl ether (MTBE) and results reported in accordance with Health and Safety h Nuisance as defined by Water Code Section 13050 does not exist at the site

1.5.2 Closure Criteria for Non-UST Sites
In 2009, the Regional Water Board’s Groundwater Committee developed an Assessment Tool for Closure of Low-Threat Chlorinated Solvent Sites (Regional Water Board 2009). The tool presents nine narrative criteria that must be satisfied to demonstrate remaining contamination will have a minimal impact on the environment, human and/or ecological receptors, and present or future drinking water resources. The criteria fall into three groups: (1) site characterization, (2) source control and mitigation and (3) demonstration that future land and water use is not adversely affected (Table 1-4). Although the document title includes chlorinated solvents, these criteria are versatile and can be applied to releases of other chemicals and mixtures. As of January 2019, this tool is in the process of being revised to clearly indicate its applicability to all low

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threat sites. The ESLs or site-specific criteria can be used in conjunction with these narrative criteria for site evaluations.

Table 1-4 – Regional Water Board Closure Criteria for Non-UST Sites No. Narrative Criterion
1 Develop a complete conceptual site model (CSM)
1a)Pollutant sources are identified and evaluated
1b)The site is adequately characterized
1c) Exposure pathways, receptors, and potential risks, threats, and other environmental concerns are identified and assessed 2 Control sources and mitigate risks and threats
2a)Pollutant sources are remediated to the extent feasible 2b)Unacceptable risks to human health, ecological health, and sensitive receptors, considering current and future land and water uses, are mitigated
2c) Unacceptable threats to groundwater and surface water resources, considering existing and potential beneficial uses, are mitigated
3 Demonstrate that residual pollution in all media will not adversely affect present and anticipated land and water uses 3a)Groundwater plumes are decreasing
3b)Cleanup standards can be met in a reasonable timeframe 3c) Risk management measures are appropriate, documented, and do not require ongoing, active Regional Water Board oversight

1.6 Other Technical Documents
From time to time, Regional Water Board staff publishes technical memoranda on key topics. In addition, Table 1-5 lists associated, stand-alone technical resource documents for specific topics that can be utilized in conjunction with the ESLs.

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Table 1-5 – Technical Resource Documents for Use with the ESLs Year Title
1996 Supplemental Instructions to the State Water Board December 8, 1995, Interim Guidance on Required Cleanup at Low Risk Fuel Sites
2009 Assessment Tool for Closure of Low-Threat Chlorinated Solvent Sites
2014
Draft Interim Framework for Assessment of Vapor Intrusion at TCE-Contaminated Sites in the San Francisco Bay Region (TCE Framework)
2016 Technical Resource Document: Petroleum Metabolites Literature Review and Assessment Framework

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2 Step-by-Step Guide: ESL Workbook
The ESLs are intended to be used in a tiered approach as outlined in Figure 2-1 and further describe throughout this section.

Figure 2-1 – Tiered Process for Selecting Screening Levels

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2.1 Conceptual Site Model
To use ESLs effectively, data should be evaluated in context. A conceptual site model (CSM) is a common way to provide this context. A CSM is a concise summary of what is currently known about site conditions and how investigation data relates to the goals for the site (USEPA 1996c; p. 4 and p. 15 through 20).

The CSM should describe the nature and extent of contamination, how contamination is moving in space and time, and what receptors are likely to be impacted. The CSM should be detailed enough to understand whether site characteristics are consistent with the assumptions used to derive ESL values.

The CSM should be updated as new information and data is obtained (USEPA 2011c). Table 2-1 lists information for inclusion in a CSM.

Table 2-1 – Information for a Conceptual Site Model
Site Data Interpretation of Site Data
Local and Regional Geology
Hydrogeology
Site Activity and Use History
Current and Future Site Use
Nearby Land and Groundwater Use
Analytical Chemistry Data
Monitoring Data
Contaminant Type(s) and Source(s)
Affected Media Type(s)
Contaminant Amount
Lateral/Vertical Contamination Extent
Degradability of Contamination
Mobility of Contamination
Receptors and Exposure Pathways
The level of detail in each CSM will vary based on the type of evaluation being conducted, severity of the contamination, and complexity of the contaminant distribution. However, all CSMs should include three basic elements described below:

1. A description of the nature and extent of contaminants at the site.

ESLs should only be used once there is a relatively clear picture of the contamination type(s) and distribution(s) at a site. This is often portrayed as a diagram depicting known or suspected sources of contaminants and concentrations of known contaminants (including isoconcentration contour maps for soil and groundwater, such as Figure 2-2). Hydrogeologic cross sections showing the delineation of the vertical extent of contamination should be prepared (e.g., Figure 2-3). A calculation of residual contaminant mass in each media can also be helpful. A summary of the site history, including operations at the site that are known or suspected to have caused the release(s), is especially valuable.

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2. A description of how contaminants are moving or changing in space and time. This evaluation should address whether the extent of known contamination is growing, migrating, or attenuating and should include an accurate discussion of geology and hydrogeology. It is critical that available geologic and topographic maps along with aerial photos be reviewed and interpreted. For new sites, this section could be brief, but for older and more complex situations, this section should summarize relevant site-specific issues such as preferential pathways (natural and man-made), vertical groundwater gradients, and evidence of biodegradation. If biodegradation is occurring at a site, the risk associated with transformation products should be discussed as well as the apparent rate of biodegradation. Boring logs, well logs, maps of subsurface utilities and other figures, as appropriate, should be created to support this evaluation. Plots of chemical concentration versus distance or time may be useful to illustrate contaminant migration or attenuation. If remediation has been conducted, the effectiveness of the remediation should be evaluated.

3. An evaluation of the potential receptors and exposure pathways. This is often shown as a chart indicating which media are impacted and the exposure pathways from each medium to potential receptors. For initial screening at the Tier 1 level, default receptors are assumed (see Section

2.3 and Figure 2-4). For more detailed evaluations, a site-specific description of the actual receptors – both human and environmental - should be included and the presence of sensitive receptors such as hospitals, schools, day care centers, wetlands, or endangered species highlighted (e.g., Figure 2-5). Exposure pathways and receptors which may be present at the site but are not considered by the ESLs should be noted (e.g., consumption of backyard produce grown in contaminated soil or ingestion of contaminated surface water by endangered species).

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Figure 2-2 – Example Illustrating Horizontal Extent of Tetrachloroethene in Shallow Groundwater

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Figure 2-3 – Example Cross Section Illustrating Contaminant Distribution

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Figure 2-4 – Default Evaluation of Receptors and Exposure Pathways Used in a Tier 1 Assessment

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Figure 2-5 – Example of a Site-Specific Evaluation of Receptors and Exposure Pathways

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2.2 ESL Workbook Content
The ESL Workbook is a Microsoft Excel file that includes multiple worksheets used to calculate and summarize all the ESLs for groundwater, soil, subslab/soil gas, and indoor air. Each worksheet is color coded and appears in the workbook in the following order:
• White Tabs – Index of Tables
• Dark Blue Tabs (Summary Tables) – Showing all possible ESLs for each media type and those selected as the Tier 1 screening value. • Red Tabs (Interactive Tool) – Allows users to input site-specific information to generate Tier 2 (T2) screening levels and cumulative risk values for a selected chemical and specific site scenario. The tool includes three separate worksheets:
o Table T2-1 (Site-Specific ESLs) – Input page for chemical(s) selection and entry of site-specific information in the yellow boxes and the site-specific T2 ESL outputs are provided in the gray boxes. o Table T2-2 (Cumulative Risk Calculator) – Input site-specific contaminant concentrations to obtain output of the calculated cumulative cancer risk and noncancer hazard index.
o Table T2-3 (Site-Specific Concerns) – Output visual CSM with media and pathway concerns for the input site-specific contaminant concentrations.
• Light Blue Tabs (Groundwater) – Calculation tables showing the parameters used to calculate the ESLs for groundwater (GW):
o Table GW-1 – Direct Exposure Human Health Risk Level Calculation o Table GW-2 – Aquatic Habitat Level Calculation
o Table GW-3 – GW Vapor Intrusion Risk Level Calculation o Table GW-4 – Gross Contamination Level Calculation
o Table GW-5 – Taste and Odor Nuisance Level Calculation • Yellow Tabs (Soil) – Calculation tables showing the parameters used to calculate the ESLs for soil (S):
o Table S-1 – Direct Exposure Human Health Risk Level Calculation o Table S-2 – Terrestrial Habitat Level Calculation

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o Table S-3 – Leaching to Groundwater Level Calculation o Table S-4 – Gross Contamination Level Calculation
o Table S-5 – Odor Nuisance Level Calculation
• Purple Tabs (Subslab/Soil Gas) – Calculation tables showing the parameters used to calculate the ESLs for subslab/soil gas (SG):
o Table SG-1 – Vapor Intrusion Human Health Risk Level Calculation o Table SG-2 – Vapor Intrusion Odor Nuisance Level Calculation • Green Tabs (Indoor Air) – Calculation tables showing the parameters used to calculate the ESLs for indoor air (IA):
o Table IA-1 – Indoor Air Direct Exposure Risk Level Calculation o Table IA-2 – Indoor Air Odor Nuisance Level Calculation • Tan Tabs (Input Parameters/Constants) – Lookup tables compiling the input parameters and constants (IP):
o Table IP-1 – Physical-Chemical Values
o Table IP-2 – Toxicity Values
o Table IP-3 – Direct Exposure Model Factors
o Table IP-4 – Maximum Contamination Levels (MCL) and Other Drinking Water Levels
o Table IP-5 – CalEPA Aquatic Habitat Goals
o Table IP-6 – USEPA and Other Aquatic Habitat Goals
o Table IP-7 – Seafood Ingestion Aquatic Habitat Goals (Risk from Bioaccumulation)
o Table IP-8 – Soil Terrestrial Habitat Goals
o Table IP-9 – Petroleum Fractions

2.3 Tier 1 ESLs – Default Conceptual Site Model
Tier 1 ESLs are selected based on conservative default Conceptual Site Model (CSM) scenario conditions listed in Table 2-2. This scenario is designed to protect sites for unrestricted land and water use, shallow soil contamination,

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shallow groundwater, and permeable soil (Section 2.4 contains more information about these and other specific site criteria and how they should be applied).

The Tier 1 ESL Workbook Summary Table presents screening levels for groundwater, soil, subslab/soil gas, and indoor air. By comparing sample data to these Tier 1 ESLs, decisions can be made regarding the need for additional site investigation, remedial action, or a more detailed risk assessment. Since a Tier 1 evaluation employs default exposure scenarios, it is most useful for screening out sites where the concentration of a single contaminant is below its ESL for a given medium or where concentrations of a limited number of contaminants are well below their respective ESLs. Exceedance of a Tier 1 ESL typically indicates the need for a Tier 2 assessment.

Table 2-2 – Tier 1 ESL Conceptual Site Model
Site Scenario Criteria Tier 1 ESL Selection
Land Use Residential
Vegetation Level Substantial
Groundwater Use Drinking Water Resource
MCL Priority over Risk Based Levels Yes
Discharge to Surface Water Saltwater & Freshwater
Groundwater VI Attenuation Factor 0.001
Soil Gas VI Attenuation Factor 0.03
Soil Contamination Depth Shallow (≤ 10 ft bgs)

2.4 Tier 2 ESLs – Selecting Site-Specific ESLs and Use of Interactive Tool
Tier 2 ESLs are selected by refining the default CSM to identify relevant pathways, receptors, and concerns specific to an individual site. For sites where the exposure scenarios and concerns are addressed in the ESLs, this intermediate approach is a relatively rapid and cost-effective option for developing site-specific screening levels in lieu of proceeding to a Tier 3 quantitative risk assessment. The following sections give a step-by-step description of how to select the correct Tier 2 ESL(s) for a specific site. These steps will aid in the selection of appropriate site-specific input criteria for the ESL Workbook Interactive Tool Input Table T2-1.

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Step 1: Check ESL Applicability and Updates
Check with the overseeing regulatory agency to determine if the ESLs can be applied to the subject site. If the answer is yes, ensure the most up-to-date version of the ESLs is being used.

Step 2: Identify Chemicals of Potential Concern
An appropriate risk evaluation must be based on the results of an adequate site investigation.
• Characterize the distribution and extent of chemicals of potential environmental concern identified in the CSM in groundwater, soil, subslab/soil gas, and indoor air within areas located both on- and off-site. • Identify maximum concentrations of chemicals present in the media of concern.

Step 3: Land Use Selection
The selected ESLs for soil, subslab/soil gas, and indoor air are based on the present use and anticipated future use of the site. Land uses are categorized based on the assumed magnitude of potential human exposure (see Section

3.4.2).

Land use should be selected with respect to the current and foreseeable future use of the site in question. Reference to adopted General Plan maps, zoning maps, and local redevelopment plans are an integral part of this process.

Discussions with local planners may help identify reasonably foreseeable changes to land use. Use of the ESL tables for sites with other land uses (e.g., parks or recreational use) should be discussed with and approved by the overseeing regulatory agency.

Two options are available in the workbook:
• Residential Land Use should be used to evaluate sites for unrestricted future land-use. This includes sites to be used for residential developments, hospitals, day care centers and other sensitive purposes (DTSC 2002). ESLs listed under this category incorporate assumptions regarding long-term, frequent exposure of children and adults in a residential setting. Screening levels for residential land use generally are considered to be appropriate for long-term use of a property, though there can be situations where short-term, more intensive exposures to soil can drive risk (e.g., construction worker soil ESL for nickel).

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• Commercial or Industrial Land Use assumes that only working-age adults will be present at the site on a regular basis. For example, directexposure assumptions incorporated into the soil ESLs for commercial or industrial land use assume shorter, less frequent exposure for receptors compared to assumptions used for residential land use receptors (e.g., less exposure time per day). However, for evaluation of commercial/industrial properties, it is recommended that site data be compared to ESLs for both unrestricted (residential) and commercial/industrial land use to avoid the requirement for possibly unneeded institutional controls, such as a deed restriction that prohibits residential land use, which would only be needed if residential ESLs are exceeded.

An “Implied Land Use Restriction” is a situation where: (1) the current land use or zoning is commercial/industrial; (2) there is low or no likelihood that the land use will change in the future; and (3) the site data are only evaluated against commercial/industrial ESLs. This situation raises the question regarding whether a land use covenant is warranted as a measure of protection for remaining contamination that exceeds residential ESLs. California Water Code section 13307.1(c) gives the Regional Water Board the Authority to determine when a deed restriction is required, with a few exceptions.

Step 4: Vegetation Level Selection
Terrestrial Habitat ESLs were derived for either “Significantly Vegetated Areas” or “Minimally Vegetated Areas”. These ESLs can be applied to either the residential or commercial/ industrial scenarios depending of the site-specific vegetation level. Several factors should be considered when determining the vegetation level of a given site, such as:

1. the level of urbanization in surrounding areas;

2. the percentage of the site that is covered by vegetation; and

3. if there is any observed animal habitat.

For example, a suburban residence with over 50% of the property is covered by vegetation could be considered a substantially vegetated area. On the other hand, almost all high-density urban scenarios could be considered minimally vegetated areas. Most commercial/ industrial sites will most likely be considered minimally vegetated areas.

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Step 5: Groundwater Use Selection
The beneficial uses of groundwater for a particular basin or area are presented in the Basin Plan. As described in Section 1.1.1, groundwater beneath the site should initially be treated as a current or potential source of drinking water. For a more site-specific analysis, the actual (likely) use of groundwater can be determined based on the locations of existing municipal or domestic supply wells, measured quality of the groundwater, and the hydrogeologic nature of the soil or bedrock containing the groundwater. State Water Board Resolution 88-63 provides criteria that can be used to determine if groundwater is likely to be used as drinking water (State Water Board 1988).

When Groundwater Use is set to nondrinking water resource, the resulting groundwater ESLs do not consider risk from direct exposure to groundwater used as tapwater (ingestion, inhalation, or dermal contact).

An “Implied Groundwater Use Restriction” is a situation where the beneficial use of groundwater includes potable uses, but the site data are compared against non-drinking water ESLs because groundwater is not potable or the groundwater is not currently used and is unlikely to be used in the future (e.g., municipal water system). In these situations, a deed restriction may be required to ensure that groundwater will not be used in the future. Further, because groundwater contamination plumes are not static, the potential for contaminant migration must be adequately assessed as well as the potential for vapor intrusion.

Step 6: MCL Priority versus Risk-Based Screening Levels Selection Choosing MCL Priority changes how the final ESL for groundwater direct exposure is selected. If MCL Priority is not chosen, the final ESL for groundwater direct exposure is the lowest of the three types of direct exposure criteria (Section 3.1.1): tapwater ESLs, MCLs, or other drinking water levels (e.g., OEHHA public health goals). If MCL Priority is chosen and a chemical has an MCL, the MCL is selected as the final ESL for groundwater direct exposure. The Tier 1 ESLs use the MCL Priority value to assess the groundwater direct exposure risk.

According to the Basin Plan, the lower of the primary and secondary Maximum Contaminant Levels (MCLs) for selected chemicals must be used as an upper bound when setting cleanup goals for groundwater designated for domestic or municipal supply use (see Section 1.1.1). MCLs are drinking water standards adopted by the California State Water Resources Control Board, Division of

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Drinking Water (DDW)2 pursuant to the California Safe Drinking Water Act.

Primary MCLs are derived from health-based criteria considering technologic and economic constraints and the feasibility of achieving and monitoring the concentrations in drinking water.

Step 7: Discharge to Surface Water Type Selection
The likelihood of a groundwater plume discharging into a nearby surface water body should be considered when selecting groundwater ESLs. If enough information is present to show that a groundwater plume extent is defined, stable, not likely to migrate further, and not discharging to surface water, then the “No Discharge Expected” can be selected in the site-specific input ESL Workbook Table 2-1 (Tier 2 Site Specific ESLs). When a groundwater plume is currently discharging, could discharge in the future, or discharge status is uncertain, in ESL Workbook Table 2-1 select the type of surface water habitat that could be affected: freshwater, saltwater, or both (in the case of estuaries).

Step 8: Soil Exposure Depth Selection
The ESLs employ two contamination depth options for soil direct exposure considerations (see Table 3-1):
• Shallow Soil Contamination (at or above 10 feet bgs): There is potential for residents, commercial/industrial workers, and construction workers to be exposed to contaminated soil at or above 10 feet bgs. This means that, for most screening level evaluations, two potentially exposed receptor populations need to be considered: 1) residents or commercial/industrial workers; and 2) construction workers. • Deep Soil Contamination (below 10 feet bgs): Construction workers may also be exposed to contaminated soil below 10 feet bgs. Regular exposure to contaminated soil at that depth by residents or commercial/industrial workers is unlikely, unless the overlying soil were removed.

If chemicals are detected in both shallow and deep soil, it is appropriate to evaluate both depth exposure intervals.

2 The California Drinking Water Program was transferred from the California Department of Public Health to the State Water Resources Control Board, Division of Drinking Water in July 2014.

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Step 9: Final ESL Determination Process
The Interactive Tool uses the site-specific scenario parameters selected by the user in ESL Workbook Table T2-1, to identify the site-specific ESLs appropriate for each medium. Figures 2-6 through 2-9 illustrate the considerations used in the determining the final screening level for groundwater, soil, subslab/soil gas, and indoor air, respectively.

Step 10: Compare Site Data to ESLs
The concentrations of up to five contaminants detected at a site can be entered into the Interactive Tool in the ESL Workbook Table T2-2 to calculate the cumulative cancer risk and hazard index. The specific concerns posed by those chemicals and concentrations will be identified in ESL Workbook Table T2-3.

Initial screening is typically performed using maximum-detected concentrations as the exposure point concentrations (EPCs). Tier 2 or Tier 3 risk evaluations may employ the use of statistical methods (e.g., 95 percent upper confidence limit of the arithmetic mean, or UCL) to estimate EPCs for specific exposure areas.

The UCL is commonly used as the EPC for soil where the data are averaged over the area/volume to which receptors could be chronically exposed. Guidance for the estimation of EPCs use of non-detect data, and other related issues is provided in the following documents: (1) Preliminary Endangerment Assessment Guidance Manual (DTSC 2015), (2) Calculating Upper Confidence Limits for Exposure Point Concentrations at Hazardous Waste Sites (USEPA 2002g), and (3) the most current version of ProUCL. As discussed in these documents, care should be exercised when determining the area and depth over which the data are averaged. For soil contaminants in an anticipated residential development, concentrations should not be averaged over an area greater than the area of the existing or anticipated residential lot. Soil leaching to groundwater data generally should not be averaged. For vapor intrusion concerns, ideally, soil gas and groundwater concentrations should not be averaged over an area greater than the floor space area of existing or anticipated buildings.

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Figure 2-6 – Final Site-Specific Groundwater ESL Determination

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Figure 2-7 – Final Site-Specific Soil ESL Determination

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Figure 2-8 – Final Site-Specific Subslab/ Soil Gas ESL Determination Figure 2-9 – Final Site-Specific Indoor Air ESL Determination

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Step 11: Compare Site Data to Background/Ambient Levels If background sampling analysis or applicable published background studies can be used to determine the naturally occurring background or ambient concentrations of chemicals of concern at a site, compare them with the site’s selected ESLs. If the site‐specific background or ambient concentrations are greater than the risk‐based ESLs, the background concentrations may be used to screen sites for excess risk posed by site contamination. This should only be done in consultation with the overseeing regulatory agency. Risk from background or ambient levels of chemicals of concern should still be documented in the screening analysis report, so those risks can be considered for risk communication and risk management decisions. Further information is provided in Section 12.4.

Step 12: Evaluate the Need for Additional Investigation, Assessment, or Remediation
Based on a comparison of available site data to the ESLs, the user should evaluate the need for additional action at the site. Additional action should be evaluated when the cumulative cancer risk is greater than 1x10-6 or the noncancer hazard index is equal to or greater than 1 at a site. Additional actions may include, but are not limited to further investigation, institutional controls, monitoring, preparation or revision of a site-specific risk assessment, source remediation, or mitigation (to protect a threatened receptor until cleanup levels are attained). Information about the calculation of cumulative cancer risk and noncancer hazard are provided in Section 3.5.

Example of Interactive Tool Use: Dry Cleaner Release of Tetrachloroethene and Stoddard Solvent
The site-specific scenario options are chosen from the drop-down menu in the first yellow box and the top five contaminants for the site are selected in the second yellow box of Table T2-1 in the Interactive Tool of the ESL Workbook, as shown in Figure 2-10. The gray box shows the output media specific Tier 2 ESLs for the five contaminants given the selected site scenario information. The basis for the selected ESL is shown to the right of each Tier 2 ESL.

For this example, available soil, groundwater, subslab/soil gas, and indoor air data were entered in the yellow box of Interactive ESL Workbook Tool Table T2- 2, as shown in Figure 2-11. The default screening soil gas attenuation factor (AF)

0.03 was also entered. In the purple box, the cancer risk and noncancer hazard for each contaminant concentration is calculated for the soil exposure pathway,

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tapwater exposure pathway, and indoor air exposure via the vapor intrusion pathway. Risk and hazard for the vapor intrusion pathway are further split into current (primarily based on indoor air data) and future (primarily based on subslab/ soil gas data) exposure scenarios (see section 3.5.1 for more information). The cumulative risk and hazards, considering all five contaminants, are shown for each media in the black box.

The Specific Concerns diagram shown in the Interactive ESL Workbook Tool Table T2-3 can be used to get a better idea of potential threats caused by specific contaminant concentrations measured at a site, shown in Figure 2-12 for this example. This diagram uses the site-specific scenario inputs and chemical input for “Contaminant 1” in Table T2-1 and the “Contaminant 1” concentration inputs from Table T2-2. Each media type (groundwater, soil, subslab/soil gas, and indoor air) is shown within a circle. Each circle is connected to a box for each of the different ESLs considered for that media type. Red X’s will appear next to all ESLs that are exceeded by the input site concentration data. The “red X visual” highlights specific media needing further evaluation and potentially response actions. As seen in Figure 2-12, the site-specific concerns for the sitespecific concentration data for this example are:
• Soil: Leaching to groundwater
• Groundwater: Human health risk from vapor intrusion to indoor air • Subslab/ Soil Gas: Human health risk from vapor intrusion to indoor air • Indoor Air: Human health risk from direct exposure
Figure 2-12 also shows that both groundwater and soil concentrations are below levels where gross contamination or odor (nuisance) would be a concern. The soil contaminant concentrations do not pose a soil exposure risk to human or ecological receptors. No risk to human health from tapwater exposure is shown since this is a nondrinking water resource and no risk to aquatic habitats is shown since no groundwater discharge to surface water is expected at the site.

2.1 Tier 3 – Develop Site Specific Screening Levels
Tier 3 Screening Levels typically are developed by either modifying Tier 2 ESLs or developing screening levels for an exposure scenario not considered in the ESLs. Tier 2 ESLs can be modified to adjust exposure factor values to those considered more representative for a particular site, given adequate justification.

Alternatively, different exposure scenarios can be developed with adequately justified algorithms, models, or inputs. Two examples of alternative exposure scenarios are consumption of garden produce and recreational swimmer exposure.

In lieu of Tier 3 screening levels, a site-specific risk assessment can be developed.

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Figure 2-10 – ESL Workbook Interactive Tool Tier 2 ESL Input and Output Table T2-1 for Example Scenario Vegetation Level:

Groundwater Use:

Select Site Contaminants:

ESL Basis ESL Basis ESL Basis ESL Basis ESL Basis
Soil (mg/kg): 8.0E-02 Leaching 8.5E-02 Leaching 1.6E+00 Leaching 1.5E-03 Leaching 2.6E+02 Terr Habitat Groundwater (μg/L): 2.8E+00 VI HHR 7.5E+00 VI HHR 2.1E+02 VI HHR 1.4E-01 VI HHR 2.5E+03 Gross Contam Subslab/ Soil Gas (μg/m³): 6.7E+01 VI HHR 1.0E+02 VI HHR 1.2E+03 VI HHR 5.2E+00 VI HHR 3.3E+04 VI Odor/Nuis Indoor Air (μg/m³): 2.0E+00 Dir Exp 3.0E+00 Dir Exp 3.5E+01 Dir Exp 1.6E-01 Dir Exp 1.0E+03 Odor/Nuis Note:

Groundwater depth is no longer a toggle for evaluating vapor intrusion. See the notes in Workbook Table GW-3 and the User's Guide Chapter 5 for further information.

Tier 2 Scenario Toggles
Soil Contamination Depth:
(Shallow ≤ 10ft bgs < Deep)
Tier 2 ESLs:

Land Use:

MCL Priority over Risk-Based:

Discharge to Surface Water:

Contaminant 5
Tetrachloroethene Trichloroethene cis-1,2-Dichloroethene Vinyl chloride Petroleum - Stoddard Solvent Contaminant 1 Contaminant 2 Contaminant 3 Contaminant 4 Click in cell and use pull-down boxes to make selection.

Table T2-1: Tier 2 ESLs
Site-Specific Input and Output
January 2019
(Rev. 1)
Commercial or Industrial
Minimal
Nondrinking Water Resource
Yes
No Discharge Expected
Shallow & Deep Soil

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Figure 2-11 – Interactive ESL Workbook Tool Table T2-2 for the Example Scenario Contaminant 1 Contaminant 2 Contaminant 3 Contaminant 4 Contaminant 5 Contaminant inputs from T2-1: Tetrachloroethene Trichloroethene cis-1,2-Dichloroethene Vinyl chloride Petroleum - Stoddard Solvent
Soil Concentration (mg/kg) - dry weight: 0.50 0.30 3,000.00 Groundwater Concentration (μg/L): 100.00 40.00 60.00 5.00 500.00 50,000 1,000 100 100 400,000
Indoor Air Concentration (μg/m3
): 10.00 0.50
Soil Gas VI Attenuation Factor (Use 0.03 for Screening): 0.0300 Cancer Risk: Tetrachloroethene Trichloroethene cis-1,2-Dichloroethene Vinyl chloride Petroleum - Stoddard Solvent Cumulative Risk Soil Exposure Risk: 1.9E-07 4.9E-08 -- -- -- 2.4E-07
Tapwater Exposure Risk: -- -- -- -- -- --
Current* Vapor Intrusion Exposure Risk: 5.0E-06 1.7E-07 -- 1.9E-05 -- 5.1E-06 Basis: Indoor Air Indoor Air Subslab/Soil Gas VI Subslab/Soil Gas VI Subslab/Soil Gas VI Indoor Air Future** Vapor Intrusion Exposure Risk: 7.5E-04 1.0E-05 -- 1.9E-05 -- 7.8E-04 Basis: Subslab/Soil Gas VI Subslab/Soil Gas VI Subslab/Soil Gas VI Subslab/Soil Gas VI Subslab/Soil Gas VI Subslab/Soil Gas VI Noncancer Hazard: Tetrachloroethene Trichloroethene cis-1,2-Dichloroethene Vinyl chloride Petroleum - Stoddard Solvent Cumulative Hazard Soil Exposure Hazard: 1.4E-03 1.7E-02 -- -- 2.7E+00 2.7E+00 Tap Water Exposure Hazard: -- -- -- -- -- --
Current* Vapor Intrusion Exposure Hazard: 5.7E-02 5.7E-02 8.6E-02 6.8E-03 8.7E+00 1.1E-01 Basis: Indoor Air Indoor Air Subslab/Soil Gas VI Subslab/Soil Gas VI Subslab/Soil Gas VI Indoor Air Future** Vapor Intrusion Exposure Hazard: 8.6E+00 3.4E+00 8.6E-02 6.8E-03 8.7E+00 2.1E+01 Basis: Subslab/Soil Gas VI Subslab/Soil Gas VI Subslab/Soil Gas VI Subslab/Soil Gas VI Subslab/Soil Gas VI Subslab/Soil Gas VI Notes:
* Current (VI exposure to current occupants of existing buildings) – Primarily based on indoor air data. See User's Guide Chapter 5 for further information.

In the absence of indoor air data, subslab/soil gas or groundwater data is used to predict current indoor air concentrations.

Subslab/soil gas data is given priority over groundwater data for current exposure calculations. The cumulative risk calculation follows the same hierarchy. ** Future (VI exposure to future occupants of existing or future buildings) – Primarily based on subslab/soil gas data. See User's Guide Chapter 5 for further information.

In the absence of subslab/soil gas data, groundwater data is used to predict future indoor air concentrations. The cumulative risk calculation follows the same hierarchy.

Selected Site Scenario (from T2-1)
Land Use: Commercial or Industrial
Vegetation Level: Minimal
Soil Contamination Depth: Shallow & Deep Soil
Groundwater Use: Nondrinking Water
Resource
MCL Priority vs Risk-Based: Yes
Discharge to Surface Water: No Discharge Expected
Subslab/ Soil Gas Concentration (μg/m3
):

January 2019 (Rev. 1) Table T2-2: Tier 2 – Site-Specific Cumulative Risk and Hazard Calculator Cumulative cancer risk and noncancer hazard are not automatically calculated across pathways because exposure via multiple pathways typically is not simultaneous. This may be performed separately as part of a site-specific evaluation. See the User's Guide Section 3.3 (Addressing Cumulative Risk and Hazard).

Enter Site Data (Leave blank when no data exits)

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Figure 2-12 – Interactive ESL Workbook Tool Specific Concerns Table T2-3 for the Example Scenario X
Land Use: Commercial or Industrial
Vegetation Level: Minimal
X Groundwater Use: Nondrinking Water Resource
MCL Priority over Risk-Based: Yes
Discharge to Surface Water: No Discharge Expected
Soil Contamination Depth: Shallow & Deep Soil
X Soil (mg/kg): 0.50
Groundwater (µg/L): 100.00
Soil Gas (µg/m3): 50,000
Indoor Air (µg/m3): 10.00
X
X
X
X
X
Subslab/ Soil
Gas (μg/m3
)

6.7E+01
Site Concentration Inputs (Table T2-2):

Selected Site Scenario (Table T2-1):

Indoor Air
(μg/m3)
Soil
(mg/kg)

3.2E+04

2.0E+00

6.7E+01
ESLs Exceeded ('X').

Further evaluation of
identified concerns
recommended.

Odor
Vapor
Intrusion
Vapor
Intrusion
Gross

5.0E+04 --
Direct
Exposure
--
Taste/
Odor

3.0E+03
Gross Aquatic
Contam. Habitat

2.8E+00
Odor

1.1E+06
Contam.

Groundwater
(μg/L)

2.8E+00
Direct
Exposure

2.0E+00
Direct
Exposure

2.7E+00

1.0E+03
Odor
Terrestrial
Habitat

4.3E+01

1.7E+02 Leaching

8.0E-02

8.0E-02
Tetrachloroethene
January 2019
(Rev. 1)
Based on "Contaminant 1" inputs in Tables T2-1 and T2-2 Table T2-3: Diagram of Specific Concerns for:

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3 Methods: Direct Exposure Human
Health Risk Screening Levels for All Media
The ESLs consider potential adverse effects to human health from chronic direct exposure to contaminated groundwater, soil, and indoor air. Direct exposure (or direct contact) refers to exposure via one or a combination of the three exposure routes (ingestion, inhalation, and dermal contact). Direct exposure human health risk ESLs are presented in three ESL Workbook tables where the exposure point is groundwater (Workbook Table GW-1), soil (Workbook Table S-1), and indoor air (Workbook Table IA-1). Table 3-1 identifies the human health direct exposure scenarios in the ESLs, including the receptors, exposure routes, and media.

Table 3-1 ‒ Human Health Direct Exposure Scenarios in the ESLs Medium/
Workbook Table
Resident
Exposure
Routes
Commercial/
Industrial Worker
Exposure Routes
Construction
Worker Exposure
Routes
Groundwater
(Table GW-1
Tapwater Columns)
Ingestion
Inhalation
Dermal
-- -- 1
Shallow Soil
(≤10 ft bgs)
(Table S-1)
Ingestion
Inhalation
Dermal
Ingestion
Inhalation
Dermal
Ingestion
Inhalation
Dermal
Deep Soil
(>10 ft bgs)
(Table S-1)
-- --
Ingestion
Inhalation
Dermal
Indoor Air
(Table IA-1) Inhalation Inhalation --
Table 3-1 Note 1 - See Frequently Asked Questions regarding construction worker exposures to groundwater.

This chapter presents the following:
• background on risk assessment and management;
• calculation of the human health direct exposure ESLs for the different media (groundwater, soil, and indoor air)
• evaluation of cumulative risk and hazard;
• risk assessment for the chemical mixtures included in the ESLs including methodology and/or application;

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• consideration of chemical transformation and generation of degradation products; and
• general information on site-specific evaluations.

3.1 Groundwater Direct Exposure ESLs
The ESLs consider potential adverse effects to humans through exposure to groundwater used as tapwater for common domestic activities, such as drinking, bathing/showering, cooking, dishwashing/laundry, and flushing the toilet. ESL Workbook Table GW-1 presents these ESLs.

The application of these ESLs to a cleanup site implies that the tapwater source is from a well located onsite with the well screened across the zone of groundwater contamination. Consideration of this exposure pathway should always be included when the designated beneficial uses of the groundwater include drinking water.

3.1.1 Direct Exposure Health Risk Criteria
ESL Workbook Table GW-1 includes screening levels from three sources as described below:
• Tapwater Screening Levels – These values are calculated in ESL Workbook Table GW-1 using the USEPA RSL resident tapwater equations for all three exposure routes (ingestion, inhalation, and dermal exposure per Table 3-1).
• Maximum Contaminant Levels (MCLs) – These values are compiled in ESL Workbook Table IP-4. MCLs are drinking water standards adopted by the California State Water Resources Control Board, Division of Drinking Water (DDW) pursuant to the California Safe Drinking Water Act. Primary MCLs are derived from health-based criteria, but they also include technologic and economic considerations based on the feasibility of detecting and monitoring for these concentrations in drinking water. The compiled values include both the Primary and Secondary MCLs. The Primary MCL values are the lowest of the Federal or California Primary MCLs and constitute the Primary MCLs applicable for California. • Other Drinking Water Levels – These values are compiled in ESL Workbook Table IP-4 and include Public Health Goals developed by the Office of Environment Health Hazard Assessment (OEHHA), Notification Levels by DDW, or Public Health Archived Advisory Levels by DDW.

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3.1.2 Hierarchy for Direct Exposure Health Risk Criteria ESL Workbook Table GW-1 determines the Groundwater Direct Exposure ESLs from the compiled criteria as described herein. First, for each chemical, the MCL Screening Levels for cancer risk and noncancer hazard are selected using the lower of the Primary or Secondary MCL. Second, the Other Drinking Water Criteria for cancer risk and noncancer hazard are selected using the more stringent of the other criteria. Third, the Final Human Health Screening Levels for cancer risk and noncancer hazard are determined using the lowest of the calculated tapwater screening levels and Other Drinking Water Criteria. Lastly, the Final MCL Priority Screening Level is determined by selecting the MCL value or, if there is no MCL value, the lowest value of the cancer risk and noncancer hazard Final Human Health Screening Levels.

The concept behind the MCL Priority category is that California MCLs can be used in place of the health risk-based levels to represent the Basin Plan water quality objectives. The groundwater Tier 1 ESLs only consider the most conservative of California primary or secondary MCLs and not the other direct exposure health risk values (also called MCL Priority) for all chemicals with established MCLs to reflect the Basin Plan water quality objectives. Therefore, the Tier 1 ESLs for groundwater are not necessarily the lowest or most stringent possible value.

3.2 Soil Direct Exposure ESLs
The ESLs consider potential adverse effects to humans through direct exposure to soil via intrusive activities such as landscaping or digging. Direct exposure for soil includes incidental ingestion, inhalation of particulates and vapors, and dermal contact. A chemical is considered volatile if either: (1) the vapor pressure is greater than 1 millimeter of mercury or (2) the Henry’s Law Constant is greater than 1x10-5 atmospheres-cubic meter/mole (USEPA 2015a). ESL Workbook Table S-1 presents these ESLs for three exposure scenarios based on land use.

The soil direct exposure ESLs are based on dry weight. Soil exposure scenarios depend on the land use, receptor, and depth of contamination as follows and per Table 3-2:
• Shallow Soil Contamination (at or above 10 feet bgs): Residents, commercial/industrial workers, and construction workers may be exposed to contaminated soil at or above 10 feet bgs. Most evaluations should consider two potentially exposed receptor populations: 1) residents or commercial/industrial workers; and 2) construction workers. • Deep Soil Contamination (below 10 feet bgs): Construction workers may also be exposed to contaminated soil below 10 feet bgs. Regular exposure to contaminated soil at that depth by residents or commercial/industrial workers is unlikely, unless the overlying soils were permanently removed.

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If chemicals are detected in both shallow and deep soil, it is appropriate to evaluate both depth exposure intervals.

Table 3-2 – Soil Human Health Direct Exposure Scenarios Soil Depth
Land Use:

Residential,
Receptor:

Resident
Land Use:

Commercial/
Industrial,
Receptor: Worker
Land Use:

Any,
Receptor:

Contruction Worker
Shallow Yes Yes Yes
Deep -- -- Yes

3.3 Indoor Air Direct Exposure ESLs
The ESLs consider potential adverse effects to humans through inhalation of vapors. ESL Workbook Table IA-1 presents indoor air ESLs for volatile chemicals for two exposure scenarios based on land use: residential and commercial/industrial. A chemical is considered volatile if either: (1) the vapor pressure is greater than 1 millimeter of mercury or (2) the Henry’s Law Constant is greater than 1x10-5 atmospheres-cubic meter/mole (USEPA 2015a).

3.4 Calculation of Human Health Direct Exposure Screening Levels
The human health direct exposure ESLs for groundwater, soil, and indoor air are calculated for specific exposure scenarios using methodologies and equations developed by USEPA with numerous inputs including target risk, physical and chemical properties, toxicity values, and exposure parameters (e.g., liters of water consumed per day). The equations used in the ESLs are listed in Appendix A. The equations combine exposure assumptions with chemical-specific toxicity values to calculate contaminant levels with a one-in-a-million (10-6) cancer target risk or a noncancer target hazard quotient (HQ) of 1. Since the levels of carcinogenic and noncarcinogenic effects caused by a given chemical are not related, both must be considered. To be conservative, the final direct exposure ESL is the lower of the cancer versus noncancer risk screening level.

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3.4.1 Background: Use of Screening Levels for Risk
Assessment
Risk assessment is the characterization of potentially adverse human health or environmental impacts resulting from exposure to contamination. The document entitled “Use of Risk Assessment in Management of Contaminated Sites” (ITRC 2008) provides detailed background regarding the development of risk assessment for use at environmental cleanup sites. The risk assessment paradigm largely was set forth by the National Academy of Sciences (NAS 1983).

Most of the methodology has been developed by the USEPA in response to passage of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA; 1980), as amended by the Superfund Amendments and Reauthorization Act (SARA; 1986), commonly called Superfund. Both federal statutes CERCLA and the Resource Conservation and Recovery Act (RCRA; 1976), as amended by the Hazardous and Solid Waste Amendments (1984) require risk assessment to determine whether remedial or corrective actions are necessary. Under California status, remedial or corrective actions can be required based on nuisance, as well as risk.

The methodologies for health-risk-based screening levels have been derived by USEPA in numerous guidance documents as part of the Superfund program, most notably Risk Assessment Guidance for Superfund (RAGS), Volume I, Parts A through E. The aspects of those documents relevant to the ESLs are described as follows, in chronological order:
• RAGS, Vol. I: Human Health Evaluation Manual, Part A, Interim Final (RAGS Part A; USEPA 1989) – This document describes cancer risk and noncancer (systemic) hazard and provides a detailed discussion on how a baseline risk assessment should be conducted. The baseline risk assessment assumes no response action has taken place and unrestricted land use. This type of risk assessment is called a forward risk assessment (ITRC 2008). It starts with a concentration of a chemical in environmental media (exposure concentration), defines exposure assumptions, calculates dose, identifies toxicity values, and estimates a cancer risk or noncancer hazard,
• RAGS, Vol. I: Human Health Evaluation Manual, Part B (Development of Preliminary Remediation Goals), Interim Final (USEPA 1991c) – This document presents the methodologies and equations used to calculate risk-based preliminary remediation goals (PRGs) for individual chemicals in soil, groundwater, and ambient air. The contemporary terminology for PRG is “risk-based screening level” or even “screening level.” This type of risk assessment is called a backward risk assessment. It begins with the selection of a target cancer risk or noncancer hazard, identifies a potential chemical in environmental media, defines the exposure assumptions, calculates a factor representing dose, identifies toxicity values, and determines the concentration of a chemical in environmental media that is

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protective of human health based on the acceptable cancer risk or hazard quotient,
• Soil Screening Guidance (USEPA 1996b and 1996c) – This guidance document provides a tiered framework for developing risk-based, sitespecific soil screening levels (SSLs) for residential use. • Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites (USEPA 2002h) – This guidance document is a companion to the preceding 1996 guidance. It primarily includes methods for developing non-residential SSLs and updated residential SSL equations considering combined exposures (ingestion and dermal absorption).
• RAGS, Vol. I: Human Health Evaluation Manual, Part E (Supplemental Guidance for Dermal Risk Assessment) (RAGS Part E; USEPA 2004b) – This document provides a number of updates regarding dermal risk assessment methodology. These include, but are not limited to, updated dermal exposure assessment equations for the water pathway (e.g., tapwater dermal contact), dermal absorption values for soil, and updated soil adherence values.
• Risk Assessment Guidance for Superfund. Volume I, Human Health Evaluation Manual (Part F, Supplemental Guidance for Inhalation Risk Assessment) (RAGS Part F; USEPA 2009a) – This document provides a new approach to human health inhalation toxicity values. In the old approach from RAGS Part A, the inhalation exposure estimate was derived based on a chronic, daily air intake. The inhalation toxicity values were the inhalation cancer slope factor (CSFi) and the inhalation reference dose (RfDi). The new RAGS Part F methodology uses the USEPA IRIS toxicity values derived as concentrations (inhalation unit risk for cancer endpoints and reference concentrations for noncancer effects). In addition, the document indicates that performing simple route-to-route extrapolations may not be appropriate because the hazard can be misrepresented without consideration of toxicokinetic differences between the routes.
• Regional Screening Levels. User’s Guide (USEPA 2018b) – This document presents the screening level equations, key assumptions, and frequent questions.

More background information on human health risk assessment and discussion of important issues is provided in the following: (1) Examination of Risk-Based Screening Values and Approaches of Selected States (ITRC 2005); (2) Use of Risk Assessment in Management of Contaminated Sites (ITRC 2008); and (3) Decision Making at Contaminated Sites – Issues and Options in Human Health Risk Assessment (ITRC 2015).

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3.4.2 Exposure Scenarios: Land Use, Receptors, and
Pathways
The default exposure scenarios for each of the three media (groundwater, soil, and indoor air) are shown in Table 3-1 and described in Sections 3.1, 3.2., and

3.3, respectively. Each scenario is developed based on one or more of these three general receptors considering land use (residential or commercial/industrial):
• Residents – Both adults and children are considered residents and are the primary receptors for a residential land use site. Children often exhibit different behaviors than adults, such as greater hand-to-mouth soil contact that can result in increased exposure to contaminated soils. In addition, children have a lower body weight relative to the predicted intake of both water and soil which results in more conservative risk-based concentrations for children compared to an adult-only assumption.

Therefore, children are the primary receptors considered for groundwater and soil direct exposure ESLs for noncancer endpoints at sites with a residential land use.
• Commercial or Industrial Workers – Primary receptors considered for sites with a commercial or industrial land use are commercial/industrial workers.

The commercial/industrial scenario represents a variety of workers, from those who spend most of their work day indoors to those who frequently work outdoors, but not workers involved in excavation activities. A commercial/industrial worker is assumed to be an adult who will have eight hours of exposure during the course of a work day as a full-time employee of a company operating onsite. The screening levels for this receptor are expected to protect other, reasonably anticipated indoor and outdoor workers at a commercial/industrial facility, as well as visitors. • Construction Workers – Construction could occur at any site, so construction/trench workers are considered for both Residential and Commercial Land Use scenarios. The activities for this receptor typically include intensive exposures to surface and subsurface soil during excavation, maintenance, and building construction projects. A construction worker is assumed to be exposed to contaminated soil during the work day for the duration of a single on-site construction project, lasting one year. Even though work durations are typically of shorter length due to the short-term nature of typical construction projects, chronic toxicity information was used when developing screening levels for the construction worker receptor. This approach is more conservative than using subchronic toxicity values since it combines relatively short exposure duration with a chronic toxicity value.

Each receptor described above has a varying level of exposure to the different media types through three general exposure routes: ingestion, inhalation, and

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dermal contact. Table 3-1 shows which exposure routes are used to calculate the risk-based screening levels for each media.

3.4.3 Screening Level Equations
The human health direct exposure ESLs for groundwater, soil, and indoor air are calculated using standard equations adopted directly from the USEPA RSLs (2018b). Lead is the one exception with soil direct exposure screening levels calculated using blood lead models (see Section 3.4.8).

3.4.4 Inputs: Target Cancer Risk and Noncancer Hazard
The target cancer risk is 1 x 10-6 and the target noncancer hazard index is unity (or 1), based on the USEPA recommened points of departure.

3.4.5 Inputs: Physical/Chemical Constants
For some risk-based screening level calculations, physical or chemical constants are needed (e.g., diffusivity in air for the volatilization factor equation for soil inhalation exposure). The physical and chemical constants (e.g., Henry’s Law Constant) for the chemicals are primarily obtained from the USEPA RSLs Chemical Specific Parameters table. Physical/chemical constant values are tabulated in ESL Workbook Table IP-1.

3.4.6 Inputs: Toxicity Values
There are four main types of toxicity values (determined from laboratory experiments) used for assessing potential adverse effects to human health in the ESL calculations:
• Two for carcinogenic effects
o Cancer Slope Factor (SF): Oral and dermal exposure
o Inhalation Unit Risk (IUR): Inhalation exposure
• Two for noncarcinogenic effects
o Oral Reference Dose (RfD): Oral and dermal exposure
o Reference Concentration (RfC): inhalation exposure

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ESL Excel Workbook Table IP-2 lists the toxicity values and sources for each chemical used to calculate the direct exposure ESLs. Since different laboratory experiments have determined the toxicity of each chemical, a single chemical may have several different toxicity values listed in different reference sources. In general, priority is given to toxicity values from peer-reviewed publications and articles that are readily available to the public and transparent about the methods and assumptions used to develop the values. Table 3-3 presents the ESL hierarchy for selecting toxicity values.

Table 3-2 – Human Health Toxicity Value Hierarchy
Teir Source
1 California Code of Regulations, Title 22, Division 4.5, sections 68400.5, 69020-69022 (“Toxicity Criteria for Human Health Risk Assessment”), effective September 4, 2018 – OEHHA values meeting regulation requirements for peer-review and Californiaspecific aspects (sensitive subpopulations considered). See also DTSC 2019a.
2 USEPA Integrated Risk Information System (IRIS)
3 Other sources (e.g., USEPA Provisional Peer-Reviewed Toxicity Values (PPRTVs), ATSDR, etc.)
Route to Route Extrapolated Toxicity Values
Route to route extrapolation refers to the use or modification of toxicity values derived based on exposures administered via one exposure route to a different exposure route. The two common applications of this extrapolation are described below.

Oral to Dermal Route Extrapolation
Experiments to determine the toxicity values SF and RfD are designed to specifically test for oral exposure. Dermal toxicity values have not been developed. The oral toxicity values can be used to derive dermal exposure toxicity values. The main difference between oral and dermal exposure is where the chemical is absorbed, either through the internal gastrointestinal (GI) tract or through the external skin, respectively. The oral toxicity values only account for toxicity from the fraction of an oral chemical dose absorbed through the GI tract (GIABS) and not the total exposure amount. Therefore, oral toxicity values must first be adjusted to consider the total exposure amount, and then they can be further adjusted using the following factors to predict the amount of chemical (in either contaminated soil or water) that will be dermally absorbed:
• Contaminated Soil

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o ABSd: Fraction of a chemical dose in soil absorbed through the skin • Contaminated Water
o FA: Fraction of a dermal chemical dose in water absorbed through the skin
o B: Ratio of a chemical’s (in water) dermal permeability coefficients for outer (stratum corneum) relative to inner (viable epidermis) layers of the skin.
o Kp: Dermal permeability coefficient of a chemical in water through the outer skin layer (stratum corneum).
o τ event: time a chemical in water takes to absorb through the skin (also lag time)
o t*: time to reach a steady state absorption rate of a chemical in water through the skin
These absorption values are also listed in the Excel Workbook Table IP-2.

Further information on evaluating dermal exposures is presented in RAGS Part E.

Oral to Inhalation Route Extrapolation
The oral toxicity values can also be used to derive inhalation exposure toxicity values. This method is not as universally accepted as the oral to dermal route extrapolation (see RAGS Part F), so the ESLs do not use extrapolated inhalation toxicity values as a rule (also see the USEPA RSL Frequent Questions). Two exceptions are cis- and trans-1,2-dichloroethene which are prevalent throughout the region at sites contaminated with chlorinated solvents (discussed below).

Toxicity Values for Cadmium
ESL Workbook Table IP-2 presents two RfDs for cadmium: one for water and one for soil. This is because the fraction of ingested cadmium that is absorbed appears to vary with the source (e.g., food versus drinking water) (USEPA IRIS accessed January 19, 2016). The food RfD is used for soil.

Toxicity Values for Dichloroethene
Cis- and trans-1,2-dichloroethene are prevalent throughout our region at sites contaminated with chlorinated solvents. Both currently lack inhalation toxicity values from the sources in the toxicity value hierarchy. To provide a tool for evaluating inhalation exposures, we extrapolated a RfC for each compound from

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the corresponding RfD available in the USEPA IRIS. This route extrapolation is also performed in DTSC HHRA Note 3.

Toxicity Values for Petroleum Mixtures
ESLs are provided for six petroleum-related mixtures: five hydrocarbon mixtures (gasoline, Stoddard solvent, jet fuel, diesel, and motor oil) and petroleum hydrocarbon oxidation products (HOPs). Due to the complexities associated with chemical mixtures and particularly petroleum mixtures, the derivation of petroleum mixture health risk-based ESLs is presented in a separate chapter (Chapter 4).

Toxicity Values for Vanadium
The RfD for vanadium is based on the RfD used in the RSLs. Although there is no RfD specifically available for vanadium through IRIS, there is a PPRTV with an oral RfD (7.0E-04 mg/kg-day). However, confidence in the primary study that was used is low (USEPA 2009h). The RSLs employ an RfD based on the oral RfD toxicity value for vanadium pentoxide by factoring out the molecular weight of the oxide ion. Vanadium pentoxide has a molecular weight of 181.88. The two atoms of vanadium contribute 56% of the molecular weight. Vanadium pentoxide's oral RfD of 9.0E-03 mg/kg-day multiplied by 56% yields a vanadium oral RfD of 5.0E-03 mg/kg-day.

3.4.7 Inputs: Exposure Factors
In the context of the ESLs, exposure factors are factors related to receptor behavior and characteristics that help determine the receptor’s exposure to a contaminant. These can include, among the many factors, the amount of particulates incidentally ingested during intrusive soil work, the surface area of skin exposed during such work considering assumptions about the clothing being worn, and the duration of the exposure. ESL Workbook Table IP-3 lists all exposure factors considered in the calculation of the ESLs. Sources for these values include the following:
• The Exposure Factors Handbook (USEPA 2011a)
• Update of Standard Default Exposure Factors (USEPA 2014a); and • Human Health Risk Assessment Note 1, Issue: Recommended DTSC Default Exposure Factors for Use in Risk Assessment at California Hazardous Waste Sites and Permitted Facilities (DTSC 2019b)

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Table 3-4 lists specific exposure factors used for each media depending on the land use. The table also differentiates the exposure factors used for carcinogenic (C) versus noncarcinogenic (NC) risk calculations.

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Table 3-3 – Exposure Factor Selection
Res Receptor
Tapwater
(from Groundwater)
Exposure
Res
Receptor
Shallow
Soil
Exposure
Res
Receptor
Deep Soil
Exposure
Res
Receptor
Indoor
Air
Exposure
Com/Ind
Receptor
Tapwater
(from Groundwater)
Exposure
Com/Ind
Receptor
Shallow
Soil
Exposure
Com/Ind
Receptor
Deep Soil
Exposure
Com/Ind
Receptor
Indoor Air
Exposure
Body Weight (BW) NC: Child
C: Age Adj.

NC: Child
C: Age Adj. Adult -- -- Adult Adult --
Soil: Surface Area
(SA) Exposed Skin -- NC: ChildC: Age Adj.

Const.

Worker -- -- Com/Ind Worker
Const.

Worker --
Water: Surface
Area (SA) Exposed
Skin
NC: Child
C: Age Adj. -- -- -- -- -- -- --
All Media:

Exposure Time (ET)
per day
-- NC: Child
C: Age Adj.

Const.

Worker -- -- Com/Ind Worker
Const.

Worker --
Water Event
Exposure Time (ET) -- NC: Child C: Age Adj.

Const.

Worker -- -- Com/Ind Worker
Const.

Worker --
Soil to Skin
Adherence Factor
(AF)
NC: Child
C: Age Adj. -- -- -- -- -- -- --
Soil Ingestion Rate
(IR) -- Resident Worker Resident -- Worker Worker Worker Water Ingestion
Rate (IR)
NC: Child
C: Age Adj. -- -- -- -- -- -- --
Exposure
Frequency (EF) Resident Resident Const.Worker Resident -- Com/Ind Worker Const.

Worker
Com/Ind
Worker
Exposure Duration
(ED)
NC: Child
C: Age Adj.

NC: Child
C: Age Adj.

Const.

Worker Age Adj. -- Com/Ind Worker
Const.

Worker
Com/Ind
Worker

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Relative Bioavailability
The USEPA RSL equations for the incidental ingestion of soil particles include a parameter for relative bioavailability (RBA). Absolute bioavailability is the portion of the ingested dose that is absorbed (USEPA 2007b). Relative bioavailability accounts for differences in the bioavailability of a contaminant between the medium of exposure (e.g., soil) and the tested medium from which the toxicity value was derived (e.g., the arsenic SF and RfD are based on drinking water studies).

The ESLs do not account for relative bioavailability with the exceptions of cadmium (described below in a separate subsection) and exposure to leadcontaminated soil (described in the Equations section of this chapter). For other chemicals, relative bioavailability could be considered as part of a site-specific evaluation. For example, DTSC has developed a recommended methodology for evaluating site-specific arsenic bioavailability in soils (DTSC 2016a).

Mutagens
The ESLs follow USEPA guidance for adjusting the screening level calculations for carcinogens that cause irreversible damage to DNA through a mutagenic mode of action (USEPA 2005). Such carcinogens are termed “mutagens.” Table 3-5 provides a list of mutagens considered in the ESLs. USEPA recommends that default adjustment factors (called age dependent adjustment factors or ADAFs) be used to account for increased potency of exposure to mutagens during early-life when children are still developing. The following generic ADAFs reflect the potential for early-life exposure (to any mutagen) to make a greater contribution to cancers appearing later in life:
• 10-fold ADAF – Represents an approximation of the weighted geometric mean tumor incidence ratio from juvenile or adult exposures in the repeated dosing studies. This adjustment is applied for the first 2 years of life, when toxicokinetic and toxicodynamic differences between children and adults are greatest.
• 3-fold ADAF – Represents an intermediate level of adjustment that is applied after 2 years of age through just below 16 years of age. This upper age limit represents middle adolescence following the period of rapid developmental changes in puberty and the conclusion of growth in body height. USEPA selected the 3-fold adjustment because it reflects a midpoint, i.e., approximately half the difference between 1 and 10 on a logarithmic scale (101/2), between the 10-fold adjustment for the first 2 years of life and no adjustment (i.e., 1-fold) for adult exposure. • 1-fold ADAF – No adjustment is applied for exposures after turning 16 years of age.

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Table 3-4 – Mutagens 1
Chemical CAS No.

Chromium VI 18540-29-9
1,2-Dibromo-3-chloropropane 96-12-8
Methylene Chloride 75-09-2
Trichloroethene 2 79-01-6
Vinyl Chloride 2 75-01-4
Benz[a]anthracene [PAH] 56-55-3
Benzo[b]fluoranthene [PAH] 205-99-2
Benzo[k]fluoranthene [PAH] 207-08-9
Benzo[a]pyrene [PAH] 50-32-8
Chrysene [PAH] 218-01-9
Dibenz[a,h]anthracene [PAH] 53-70-3
Indeno[1,2,3-cd]pyrene [PAH] 193-39-5
Table 3-5 Notes:

Note 1 – Carcinogens considered by USEPA to act
through a mutagenic mode of action causing irreversible damage to DNA.

Note 2 – Mutagen has a chemical-specific risk equation
These generic ADAFs are used only when no chemical-specific data are available to directly assess cancer susceptibility from early-life exposure to a mutagen. The adjustment factors are derived from a weighted geometric mean of the data evaluated and will both over-estimate and under-estimate the potential potency for early-life exposure for chemicals with a mutagenic mode of action for carcinogenesis. For this reason, the guidance emphasizes that chemical-specific data should be used in preference to these default adjustment factors whenever such data are available.

Chemical-specific data are available for TCE and vinyl chloride indicating increased cancer susceptibility from early-life exposure to these mutagens.

Chemical-specific intake equations are used for these chemicals, as discussed below.
• TCE – The TCE-specific equation in the RSLs employ combined mutagenic and carcinogenic equations that combine mutagenic concerns for the kidney endpoint along with the default ADAFs and then cancer concerns for the remaining endpoints. There is sufficient evidence to conclude that a mutagenic mode of action is operative for TCE-induced kidney tumors (USEPA 2011b). However, the data are inadequate for

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complete quantification of early-life susceptibility (i.e., development of TCE-specific ADAFs) for all of TCE’s carcinogenic endpoints (liver and non-Hodgkin lymphoma). The inhalation unit risk and oral slope factor estimates for TCE reflect lifetime cancer risk for all endpoints (kidney, liver, and) and all modes of action.
• Vinyl Chloride – The vinyl chloride-specific equation in the RSLs employs a two-fold adjustment factor for the estimated cancer risk to account for early life exposure (USEPA 2000a).

3.4.8 Exception: Soil Noncancer Screening Levels for Lead The soil direct exposure noncancer screening levels for lead are calculated using blood lead models rather than the standard USEPA equations and inputs. Blood lead models are used since there is no consensus RfD for lead. (Note – OEHHA Public Health Goal for lead is used for the noncancer groundwater direct exposure ESL). The toxic endpoint used in the models represents the incremental increase in children’s blood lead level corresponding to an IQ reduction of up to one point. This is the benchmark incremental change criterion for lead and the value is one microgram per deciliter (1 µg/dL; OEHHA 2007); in the models this is labeled the “blood lead level of concern.” Use of this blood lead value complies with the California Toxicity Criteria regulation (see Table 3-3).

Two blood lead models are employed to calculate the soil direct contact levels for lead. Both blood lead models employ central tendency soil ingestion rates rather than reasonable maximum exposure ingestion rates used in the standard USEPA soil direct exposure equations. The two blood lead models include:
• The LeadSpread 8 (DTSC 2011a) is used to estimate the concentration in soil that would lead to a 1 μg/dL increase in blood lead for a child resident exposed to that soil. The central tendency soil ingestion rate for a child resident is 100 milligrams per day.
• The DTSC-Modified USEPA Adult Lead Model, which is included in the LeadSpread 8 Excel workbook, (DTSC 2011a) is used to estimate the concentration in soil that would lead to a 1 μg/dL increase in blood lead for a pregnant adult worker exposed to that soil. For the commercial/industrial worker, the central tendency soil ingestion rate is 50 milligrams per day.

For the construction worker, the central tendency soil ingestion rate is 100 milligrams per day, which reflects more intensive soil contact (USEPA 2016a).

3.5 Addressing Cumulative Risk and Hazard
Risks posed by direct exposure to multiple chemicals are considered as additive or cumulative. For example, the total risk of cancer posed by the presence of two

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carcinogenic chemicals in soil is the sum of the risk posed by each individual chemical. The same is true for chemicals that cause noncarcinogenic health effect.

At sites where more than one contaminant is present, cumulative cancer risk and noncarcinogenic hazard should be evaluated. The following example is provided:

For cancer risk estimates, divide the site-specific concentration by the ESL designated as being based on a cancer endpoint. Sum the ratios for each chemical and multiply the total by 10-6 (equation 1).

Risk = ��
Conca
ESLa
� + �
Concb
ESLb
� + �
Concc
ESLc
� + … + �
Conci
ESLi
�� x 10-6
(equation 1)
For noncancer hazard estimates, divide the site-specific concentration by the ESL designated as based on a noncancer endpoint and sum the ratios. While the individual ratio is referred to as a hazard quotient (HQ), the cumulative ratio represents a noncarcinogenic hazard index (HI) (equation 2).

HI = ��
Conca
ESLa � + �
Concb
ESLb
� +�
Concc
ESLc � + … + �
Conci
ESLi
��
(equation 2)
Further evaluation can include segregation of hazard indices by effect and mechanism of action when different endpoints and/or target organs are known for the specific chemicals of concern. Ideally, noncarcinogens are grouped according to their mechanism of action, but more commonly they are grouped according to target organ. If the hazard index exceeds 1 then it is appropriate to re-aggregate the hazard index by adding only the hazard quotients of chemicals that affect the same endpoint or target organ. This consists of identifying all of the major effects and target organs for each chemical and classifying the chemicals according to target organ(s) or mechanism of action. This analysis is not simple and should be performed under the oversight of a toxicologist.

Calculating cumulative risk and hazard across pathways should not be performed unless a well-developed CSM considering sources, release mechanisms, migration pathways, exposure routes, and receptors indicates such calculations are appropriate. In most cases, exposures via different pathways will not be simultaneous (e.g., outdoor versus indoor exposure pathways).

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3.5.1 Workbook Tier 2 Risk and Hazard Calculator
The interactive portion of the Workbook (Tier 2) can be used to calculate cumulative risk and hazard for up to five chemicals (Table T2-2). The cumulative risk and hazard are calculated for three different exposure pathways:
• Soil Exposure – Based on soil data
• Tapwater Exposure – Based on groundwater data
• Vapor Intrusion (VI) Exposure:
o Current (VI exposure to current occupants of existing buildings) – Primarily based on indoor air data. In the absence of indoor air data, subslab/soil gas or groundwater data is used to predict indoor air concentrations. Subslab/soil gas data is given priority over groundwater data for these calculations.
o Future (VI exposure to future occupants of existing or future buildings) -Primarily based on subslab/soil gas data since current indoor air data might not be representative of vapor intrusion conditions in new construction or existing buildings as they age over time. In the absence of subslab/soil gas data, groundwater data is used to predict future vapor intrusion risk and hazard.

3.6 Exceptions: Human Health Screening Levels for Chemical Mixtures
The ESL Workbook primarily includes screening levels for individual chemicals, but there are also some screening levels for chemical mixtures or groups of - related compounds. Pertinent details relevant to use of the screening levels for these mixtures are presented in this section because the screening levels are either: (1) derived differently or (2) used differently (e.g., laboratory results may need to be aggregated differently for proper comparison).

3.6.1 Background: Assessing Health Risks from Chemical
Mixtures
Chemical mixtures are combinations of two or more chemical substances regardless of source (USEPA 1986). They can include highly complex mixtures created from a single source or process (e.g., diesel exhaust), complex mixture of related compounds from a commercial process (e.g., gasoline, pesticide formulations), or unrelated compounds stored or disposed in the same area and released together. Although occasionally a mixture is well characterized, more often than not only some components (chemicals in the mixture) are known,

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exposure data are uncertain (e.g., analytical methods do not detect all the components), and toxicologic data on the known components are limited.

USEPA provides general guidelines for health risk assessment of chemical mixtures (USEPA 1986, 2000e) The two major approaches are whole mixture versus components. The preferred approach to health risk evaluation of chemical mixtures is to perform the assessment using health effects and exposure data on the whole mixture. The alternative approach based on a mixture’s chemical components is only recommended for relatively simple, identified mixtures with a dozen or fewer chemical constituents. Key elements of these approaches are summarized below:
• Whole Mixture – The evaluation options for whole mixtures (e.g., diesel) depend on data availability for the mixture of concern, a sufficiently similar mixture, or a group of similar mixtures. “Sufficiently similar” refers to a mixture that is close in composition to the mixture of concern and has identical or at least indistinguishable toxicologic consequences from exposure. Such a determination of sufficient similarity should be accompanied by appropriate analysis (e.g., acceptability of the surrogate and uncertainty). Groups of similar mixtures are identified as having chemically-related structures that act by a similar mode of action.3 • Components – The evaluation options for components depend on the toxicologic characteristics (act similarly or independently) and whether there is data on toxicologic interactions. While the use of the whole mixture approach inherently provides interactions information, this is not the case for the components approach. When adequate interactions information is lacking, dose addition or response addition models are recommended. Further information on dose addition and response addition is as follows:
o Dose addition refers to chemical behavior as a concentration or dilution of every other chemical in the mixture (components act similarly). The biological basis for dose addition is the similarity of chemical components regarding toxicologic behavior, such as toxic mechanism, mode of action, or endpoint. There are three methods based on dose addition:

1. Relative potency factor (RPF) – The RPF method employs empiricallyderived scaling factors based on the toxicity studies for the effect and exposure conditions of interest. An example is the carcinogenic PAHs (see Section 3.6.7).

3 Mode of action – Series of key events and processes starting with interaction of an agent with a cell, and proceeding through operational and anatomical changes causing disease formation (USEPA 2000e).

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2. Toxicity equivalence factor (TEF) –The TEF method is a special case of the RPF method where extensive mechanistic information shows all the toxic effects of concern share a common mode action. An example of the TEF is dioxins and furans discussed in a later section. The scaling factors represent the toxicity of the component relative to the toxicity of one component, the index chemical, typically the best-studied chemical.

3. Hazard index (HI) – The HI method requires only similarity in target organ, and this is routinely used to evaluate the cumulative hazard posed by noncarcinogens. Following these assumptions, the combined toxicity of the individual components can be estimated using the sum of their doses which are scaled for potency relative to another component of the mixture for which adequate dose-response information is available. o Response addition is recommended for mixture components that act on different systems or produce effects that do not influence each other, and, thus, can be assumed to act independently. For example, response addition is appropriate for a two-chemical mixture where the body’s response to the first chemical is the same regardless of the presence of the second chemical (components act independently).

This approach is routinely applied to evaluate risk from exposure to carcinogens.

3.6.2 Chlordane
The ESLs for chlordane are based on the technical grade chlordane chemical mixture (CAS 57-74-9). Chlordane was used as a pesticide in the United States from 1948 to 1988 (ATSDR 1994). Chlordane is a mixture of related chemicals, of which about 10 are major components. Some of the major chemicals are trans-chlordane (gamma-chlordane), cis-chlordane (alpha-chlordane), ßchlordene, heptachlor, and trans-nonachlor. Further information on chlordane composition is provided in the RSL Frequent Questions (USEPA 2018b).

Some laboratory analytical methods will either analyze the chlordane mixture as a whole, or individual chlordane isomers separately (e.g., cis- and trans- isomers in USEPA Method 8080). The chlordane mixture (CAS 57-74-9) result should be used for comparison to the chlordane ESL. Note that the ESLs employ the CAS number for chlordane listed in the OEHHA Toxicity Criteria Database (CAS 57- 74-9), whereas the RSLs use CAS 12789‐03‐6, which is the same number used by IRIS.

Weathered chlordane is expected to include its metabolite heptachlor epoxide.

There are separate ESLs for heptachlor and heptachlor epoxide.

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3.6.3 DDD, DDE, and DDT
The ESLs present separate screening levels for:
• dichlorodiphenyltrichloroethane (DDT),
• dichlorodiphenyldichloroethylene (DDE) and
• dichlorodiphenyldichloroethane (DDD)
DDT is a toxic pesticide that was once widely used to control pests on agricultural crops and insects that carry diseases like malaria and typhus but is now used in only a few countries to control malaria (ATSDR 2002). Technicalgrade DDT is a mixture of three forms, p,p’-DDT (85%), o,p’-DDT (15%), and o,o’-DDT (trace amounts). Technical grade DDT may also contain DDE and DD) as contaminants. DDD was also used to kill pests, but to a far lesser extent than DDT. Both DDE and DDD are breakdown products of DDT.

3.6.4 Dioxins and Furans
The ESLs present a single entry to screen chlorinated dibenzo-p-dioxins (CDDs) and chlorinated dibenzofurans (CDFs): 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic of these compounds. Other specific CDD and CDF molecules (dioxin-like compounds) have been assigned toxicity equivalence factors (TEFs) by the World Health Organization that scales their toxicity to that of 2,3,7,8-TCDD, which has a TEF of 1 (Table 3-6; van den Berg et al. 2006). In practice, each individual CDD or CDF concentration is multiplied by its TEF and the results summed. The summation is called the toxic equivalents (TEQ) or dioxin TEQ. Laboratory analytical reports for dioxin or furan mixtures typically calculate this for each sample. The TEQ summation can then be compared to the ESL for 2,3,7,8-TCDD.

Dioxins are molecules that contain a 6-membered ring with two double bonds and two oxygen atoms in the ring, while furans contain 5-membered ring structures with two double bonds and one oxygen atom in the ring. The dioxins and furans of greatest environmental concern are CDDs and CDFs, which include 210 compounds with related chemical structures and physiological effects. These chlorinated chemical mixtures are mainly found in the environment as unintentionally generated byproducts of certain chemical processes such as:
the incomplete combustion of materials containing chlorine (e.g., plastic); chemical manufacturing of chlorinated compounds (e.g., herbicides like pentachlorophenol, wood preservatives, and ethylene dichloride); and, natural processes such as forest fires and volcanic eruptions/emissions (USEPA 2010).

The TEF methodology, a component mixture method, is used to evaluate human health risks posed by mixtures of dioxin-like compounds, using TCDD as the index chemical (USEPA 2010). Dioxin-like compounds are structurally and toxicologically related halogenated aromatic hydrocarbons. The TEFs are to be

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used for all effects mediated through aryl hydrocarbon receptor binding by the DLCs including cancer and noncancer effects.

When evaluating appropriate cleanup goals for dioxins, HERO Human Health Risk Assessment Note 2, Issue: Remedial Goals for Dioxins and Dioxin-like Compounds for Consideration at California Hazardous Waste Sites (DTSC 2017) should be consulted.

Table 3-5 – World Health Organization Toxic Equivalency Factors for Dioxins and Furans (2005)
Compound TEF 1
2,3,7,8-TCDD 1
1,2,3,7,8-PeCDD 1
1,2,3,4,7,8-HxCDD 0.1
1,2,3,6,7,8-HxCDD 0.1
1,2,3,7,8,9-HxCDD 0.1
1,2,3,4,6,7,8-HpCDD 0.01
OCDD 0.0003
2,3,7,8-TCDF 0.1
1,2,3,7,8-PeCDF 0.03
2,3,4,7,8-PeCDF 0.3
1,2,3,4,7,8-HxCDF 0.1
1,2,3,6,7,8-HxCDF 0.1
1,2,3,7,8,9-HxCDF 0.1
2,3,4,6,7,8-HxCDF 0.1
1,2,3,4,6,7,8-HpCDF 0.01
1,2,3,6,7,8,9-HpCDF 0.01
OCDF 0.0003

3.6.5 Endosulfan
The ESLs present screening levels for endosulfan (CAS 115-29-7) which was sold as a mixture of two different forms of the same chemical (referred to as alpha- and beta-endosulfan) (ATSDR 2015). In the environment, endosulfan is present as a mixture of alpha, beta and endosulfan sulfate (a degradation product). Laboratory analyses typically evaluate samples for the individual components rather than the mixture as a whole. For instance, USEPA Method

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8080 includes Endosulfan I (alpha Endosulfan; CAS 959-98-8), Endosulfan II (beta Endosulfan; CAS 33213-65-9), and Endosulfan sulfate (CAS 1031-07-8) as separate analytes. The results of each of the three component chemicals should be added together to obtain the total endosulfan mixture concentration for comparison to the endosulfan ESLs.

3.6.6 Polychlorinated Biphenyls (PCBs)
The ESL Workbook includes a single entry for polychlorinated biphenyls (PCBs), where the toxicity value is based on the “high” risk and persistence tier listed in IRIS (accessed January 28, 2016) for CAS 1336-36-3. This ESL can be compared to laboratory analytical results for any Aroclor mixture.

PCBs are a group of synthetic chlorinated organic chemicals that were produced for industrial applications because of their inflammability, chemical stability, and insulating properties (USEPA 1996e; ATSDR 2000). Commercial mixtures in the United States were marketed under the Aroclor trade name (Boehm 2006). The Aroclor mixtures were coded depending on the molecule size and weight percent of chlorine in the formulation. For instance, in Aroclor 1254, the PCB molecule has 12 carbons, and the mixture consists of 54% chlorine by weight.

Manufacturing of Aroclor in the United States stopped in 1977 in response to the passage of the Toxic Substances Control Act (TSCA).

Cancer toxicity studies of PCB mixtures indicate that Aroclor 1254 and Aroclor 1260 have the highest observed potencies (USEPA 1996e). The USEPA document PCBs: Cancer Dose-Response Assessment and Application to Environmental Mixtures (USEPA 1996e) presents different oral cancer slope factors for different tiers of risk and persistence for certain PCB mixtures. Even though some PCBs demonstrate dioxin-like modes of action, USEPA (1996e) recommends this mixtures approach rather than the TEF approach because relatively few PCB congeners are dioxin-like.

3.6.7 Polycyclic Aromatic Hydrocarbons (PAHs)
The ESL Workbook includes screening levels for 16 polycyclic aromatic hydrocarbons (PAHs), presented in alphabetical order (not grouped). These 16 PAHs are identified as priority pollutants by USEPA and are listed in Table 3-7.

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Table 3-6 – PAHs in the ESLs and Relative Potency Factors for the Carcinogenic PAHs
PAH Compound CAS
No.

Number of
Benzene
Rings
Carcinogenic
?
Relative Potency
Factor (RPF)1
Acenaphthene 83-32-9 3 No --
Acenaphthylene 208-96-
8 3 No --
Anthracene 120-12-
7 3 No --
Benzo[a]anthracene 56-55-3 4 Yes 0.1
Benzo[b]fluoranthene 205-99-
2 4 Yes 0.1
Benzo[k]fluoranthene 207-08-
9 4 Yes 0.01
Benzo[g,h,i]perylene 191-24-
2 5 No --
Benzo[a]pyrene 50-32-8 5 Yes 1.0 (index compound)
Chrysene 218-01-
9 4 No 0.001
Dibenz[a,h]anthracene 53-70-3 5 Yes 1.0
Fluoranthene 206-44-
0 3 No --
Fluorene 86-73-7 2 No --
Indeno[1,2,3-cd]pyrene 193-39-
5 5 Yes 0.1
Naphthalene 91-20-3 2 Yes --2
Phenanthrene 85-01-8 3 No --
Pyrene 129-00-
0 4 No --
Table 3-7 Notes:

Note 1 –The relative potency factor (RPF) values for seven carcinogenic PAHs (excluding naphthalene) are the same as currently used by the USEPA RSLs, which are sourced from USEPA (1993a).

Note 2 – As indicated by DTSC (2009), naphthalene is considered to be a carcinogenic toxic air contaminant and no TEF is listed because naphthalene is evaluated separately from the other carcinogenic PAHs. It is not included the BaP equivalent value calculation.

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In a screening-level risk assessment, the PAH compounds are evaluated using one of two approaches:
• Noncarcinogenic PAHs and naphthalene – These PAHs are evaluated by comparing the laboratory analytical results to their chemical-specific riskbased screening levels; • Seven carcinogenic PAHs (listed in Table 3-8) – The laboratory analytical results can be evaluated using one of two approaches. The results can either be aggregated using the relative potency factor (RPF) methodology specific for cPAHs to calculate a benzo[a]pyrene (BaP) equivalents (BaPeq) concentration. The USEPA RPFs are listed in Table 3-7. The BaPeq concentration is then compared to the BaP risk-based screening levels. Alternatively, comparison to the individual risk-based screening levels is possible. The oral cancer slope factors for the other cPAHs are scaled to BaP using the appropriate RPF.

PAHs, also known as polynuclear aromatic hydrocarbons (PNAs), are a class of compounds consisting of two or more fused aromatic rings (Boehm 2006). The sources of PAHs are varied and commonly grouped as either petrogenic (e.g., crude oil) or pyrogenic (e.g., incomplete combustion of organic substances such as fuels or wood). Naphthalene is the simplest PAH and consists of two fused benzene rings. BaP may be the most widely recognized PAH because it was the first chemical carcinogen to be discovered. Hundreds of PAH compounds have been identified, and there are potentially tens of thousands of possible PAH structures from the smallest (naphthalene C10H8) through the largest, coronene (C24H12).

The number of PAHs tested in environmental investigations varies depending on the application. For soil and groundwater investigations, typically, only the 16 USEPA Priority Pollutant PAHs are tested. These PAHs originally were selected by USEPA in the 1970s because they: (1) had the most toxicological information; (2) were suspected to be the most harmful; and, (3) had been detected at the highest concentrations (thus posing the highest exposure risk) at National Priority List sites (ATSDR 1995d). For sediment investigations, USEPA (2003a, 2009i) recommends analysis for 34 PAH compounds as an operational definition of total PAHs.

Because PAHs are widespread in the environment, ambient PAH concentrations can be detected at a site. The DTSC Advisory, Use of the Northern and Southern California Polynuclear Aromatic Hydrocarbon (PAH) Studies in the Manufactured Gas Plant Site Cleanup Process (DTSC 2009), although intended for manufactured gas plant (MGP) sites, could be consulted for information on how to evaluate whether PAH concentrations in site soil may reflect ambient conditions.

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3.6.8 Petroleum Mixtures
ESLs are provided for six petroleum-related mixtures: five hydrocarbon mixtures (gasoline, Stoddard solvent, jet fuel, diesel, and motor oil) and petroleum hydrocarbon oxidation products (HOPs). The derivation of petroleum mixture health risk-based ESLs is presented in Chapter 4.

3.7 Site-Specific Evaluations
Options for site-specific human health risk evaluations can include site-specific (quantitative) risk assessments (Tier 3), development of alternative exposure scenarios (e.g., trespasser), the relatively minor modification of screening levels by use of non-default exposure factors or fate and transport considerations, or other options. Alternative approaches will be considered, provided there is adequate technical justification. For regulatory review, either a detailed work plan should be submitted, or a thorough scoping meeting conducted before completing the evaluation or submitting a report of findings. This important step reduces the likelihood of unnecessary and costly work and greatly improves the likelihood of regulatory concurrence.

Typical site-specific issues that necessitate discussions with the overseeing regulatory agency include the following:
• Determination of exposure units/areas and hotspots;
• Soil exposure depths;
• Exposure scenario development including evaluation of hypothetical future use of the land (e.g., residential scenario for unrestricted use and need for a land use covenant) and water (e.g., beneficial use);
• Use of averaging;
• Background/ambient concentrations of chemicals (e.g., metals); and • Use of the construction worker pathway to evaluate need for engineering and health and safety controls rather than cleanup.

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4 Methods: Petroleum Mixture Screening
Levels
What is TPH?
Previously, the petroleum mixture ESLs in the ESL Workbook were named TPH (total petroleum hydrocarbons) ESLs after the bulk analytical methods (e.g., USEPA Method 8015B). This edition of the ESLs replaces “TPH” with “Petroleum” in the Workbook (e.g., petroleum-jet fuel). “TPH” is reserved for the analytical methods designed to measure the bulk of petroleum hydrocarbons from a release. Section 4.5 discusses how to use TPH analytical methods to estimate concentrations of the six petroleum mixtures for comparison against the corresponding ESLs while Section 4.6 discusses the use of TPH fractionation methods for site-specific evaluations.

This chapter supplements Chapter 3 by describing the derivation of health-risk based ESLs for six petroleum mixtures for groundwater, soil, and indoor air. The six petroleum mixtures are:
• Five petroleum hydrocarbon mixtures: gasoline, Stoddard solvent, jet fuel, diesel, and motor oil and
• One nonhydrocarbon mixture: Petroleum hydrocarbon oxidation products (HOPs), which are generated by the partial transformation of petroleum hydrocarbons due to biodegradation and/or photooxidation.

These petroleum mixtures are listed in the ESL Workbook tables from lowest to highest boiling point: gasoline, Stoddard solvent, jet fuel, diesel, HOPs, and motor oil. Use of the petroleum mixture ESLs as part of a health risk evaluation that includes individual petroleum compounds ensures a more complete accounting of all petroleum-related compounds present and their potential toxicities and limits the potential underestimation of risk.

In general, the ESLs are not used at sites that are subject to the Low-Threat Underground Storage Tank Closure Policy (LTCP; State Water Board 2012b).

Specifically, the LTCP does not the use the ESLs to screen contaminants at petroleum-contaminated sites. Instead the LTCP provides closure levels for carcinogens and general (narrative) criteria. ESLs may be used at sites with “unique attributes” to screen for constituents not already addressed by the LTCP.

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4.1 Background
The first under Regional Water Board oversight to develop health-risk based levels for petroleum/TPH mixtures was the Presidio of San Francisco (Montgomery Watson 1995). The ESLs, first developed in 2000, have always included human health-risk based petroleum/TPH mixtures screening levels. In May 2013, the basis of the petroleum/TPH mixture ESLs was changed to a fraction approach for common petroleum mixtures. Our approach is described in Sections 4.2 and 4.3.

The following subsections 4.1.1 – 4.1.3 present technical background and the rationale for the development of the petroleum mixture ESLs.

4.1.1 Petroleum Chemistry
Hydrocarbons are chemicals composed of hydrogen and carbon atoms (only) which make up the organic molecules that constitute the majority of the crude oil mass. Most crude oils are complex mixtures containing tens of thousands of compounds, including hydrocarbons and nonhydrocarbons. The latter include heteroatoms (nitrogen, sulfur, or oxygen atoms; also, NSO) (Stout et al. 2002).

Whereas most hydrocarbon compounds are nonpolar or moderately polar (watersoluble), NSO compounds are significantly more polar because they contain strongly electronegative heteroatoms. In addition, there are smaller amounts of organometallic compounds and inorganic salts in crude oils. Crude oils are refined to produce different petroleum fuels, solvents, and oils based on performance needs and specifications. Much of the NSO (polar) compound content in crude oils is removed in the refining process but biofouling/biodegradation after the refining process may inadvertently generate some NSO compounds in the final products before they leave the refinery.

The hydrocarbons can be divided into two broad classes based on molecular structure and electron distribution:
• Aliphatic hydrocarbons are nonpolar because electrons are shared fairly evenly between carbon and hydrogen. In other words, there is no electron excess (partial negative charge) or deficit (partial positive charge) in parts of the molecule that would facilitate the interaction with polar molecules such as water. Water molecules have a substantial negative charge on the oxygen and partial positive charges on the hydrogen atoms. Aliphatics can further be divided into several classes including straight-chain, saturated aliphatics (alkanes); branched alkanes (isoalkanes); cyclic alkanes (cycloalkanes); and various unsaturated aliphatics (alkenes and alkynes).

Examples of aliphatics include n-hexane (C6, straight-chain or linear alkane), cyclohexane (C6, cyclic alkane), and propene (C3, alkene).

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• Aromatic hydrocarbons are moderately polar because they have sets of conjugated double bonds that lead to “clouds” of loosely attached “delocalized” electrons (partial negative charges) which facilitate interactions among the aromatics as well as between the aromatics and other polar molecules. Aromatic hydrocarbons consist of one or more unsaturated ring(s) and can contain aliphatic attachments. Examples include benzene (C6, a single ring aromatic or monoaromatic hydrocarbon), toluene (C7, also methylbenzene) and naphthalene (C10), which has a fused, double ring and is the smallest polycyclic aromatic hydrocarbon (PAH).

Aliphatic and aromatic hydrocarbons differ in their physical, chemical, and biological properties. Table 4-1 illustrates some of these differences. For instance, n-hexane (C6 aliphatic) is about 15-times more volatile than benzene (C6 aromatic) based on vapor pressure. Benzene, however, is about 200-times more soluble in water than n-hexane, a trait directly attributable to the polarity of benzene. Thus, the chemical properties of petroleum mixtures will vary depending on the individual compounds present and their proportions within the mixture.

Table 4-1 – Physical-Chemical Properties of Selected Hydrocarbons and Hydrocarbon Oxidation Products
Chemical Molecular
Formula
Boiling
Point
(ºC)1
Vapor
Pressure
(mm Hg)1
Henry’s Law
Constant
(atmm3/mol)1
Solubility
(µg/L)1
Benzene C6H6 80 9.5E+01 5.6E-03 2.0E+06
n-Hexane C6H14 69 1.5E+02 1.8E+00 9.5E+03
2-Hexanone 2 C6H12O1 128 1.4E+01 9.3E-05 7.7E+06
Hexanoic
Acid 2 C6H12O2 205 4.4E-02 7.6E-07 5.8E+06
Phenanthrene C14H10 327 4.3E-05 1.5E-05 6.8E+02
1H2NA 3 C11H8O3 375 1.3E-07 1.5E-10 2.3E+06
Table 4-1 Notes:

Note 1 ‒ Physical-chemical parameter values from USEPA Estimation Programs Interface (EPI) Suite
Note 2 ‒ n-Hexane metabolites: 2-hexanone and hexanoic acid Note 3 ‒ Phenanthrene metabolite: 1H2NA (1-hydroxy-2-naphthoic acid)

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4.1.2 Environmental Fate of Released Petroleum
Although petroleum mixtures can accumulate partial degradation products during storage and transmission, their composition tends to change more rapidly after release to the environment due to a variety of weathering processes. These include physical, chemical, and/or biological processes. Typically, the more dominant processes are physical and biological but the extent to which they occur depends on the structure of a given hydrocarbon and other factors:
different hydrocarbons have different tendencies to volatilize, dissolve, or biodegrade, based on their structure, size, and polarity (ITRC 2018). Further information on weathering is presented in TPH Criteria Working Group (1997b) and ITRC (2018).

Physical Weathering
Physical weathering processes include volatilization, dissolution, and adsorption.

These partitioning processes redistribute certain types of hydrocarbons from the released nonaqueous phase liquid (NAPL) into other phases. Mainly low carbon range aliphatics and some of the smaller aromatics migrate into vapor. Some hydrocarbons adsorb onto soil particles. Mainly low and medium carbon range aromatics and some low carbon range aliphatics migrate into water. The remaining NAPL is continually depleted as these components are lost. This redistribution or partitioning is the result of different chemicals within petroleum having different properties as well as mixture effects, such as their effective volatility and solubility, which is based on Raoult’s Law (ITRC 2018), and environmental conditions such as temperature. These processes can result in vapor and water phase compositions significantly different from the original or remaining NAPL.

Biological Weathering (Biodegradation)
Hydrocarbons are highly reduced organic molecules with many hydrogen atoms providing an abundance of electrons for reactions with chemicals that can accept electrons. This explains their reaction with oxygen, which acts as terminal electron acceptor. After release to the environment, petroleum mixtures typically undergo (at least some) biodegradation in the presence of water. Unlike combustion, biodegradation is a stepwise process that produces many partial oxidation products that often have multiple functional groups. Microbial biodegradation is a process in which groups or “consortia” of microorganisms break down the hydrocarbons. There are many factors that influence the rate and extent of biodegradation of a given type of hydrocarbons, notably the composition of the released mixture, nature of the resident microbial population, availability of oxygen or other electron acceptors, and overall conditions for the

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growth of microbial populations such as nutrient availability (e.g., nitrogen, phosphorus), geochemistry, pH, and soil temperature. Biodegradation occurs more rapidly in aerobic conditions but can occur in anaerobic conditions, albeit more slowly (TPH Criteria Working Group 1998b).

Susceptibility to biodegradation varies substantially for the different types of hydrocarbons, especially under anaerobic conditions. In general, the greater branching of hydrocarbons correlates with increased resistance from microbial attack (Atlas 1981; Watson et al. 2002; Booth et al. 2007). For example, nalkanes are considered the most susceptible to biodegradation whereas cycloalkanes are very resistant.

Biodegradation, in contrast to oxidation by combustion, is a complex, stepwise, and therefore comparatively slow, process. However, stepwise biodegradation can ultimately also lead to carbon dioxide and water as the final products (mineralization). Biodegradation of hydrocarbon molecules is slow because the stepwise process requires many different catalytic activities and even a single type of hydrocarbon may require more than one type of microorganism to accomplish mineralization. Numerous transformation products are generated during biodegradation of petroleum hydrocarbons (Atlas 1981; Bekins et al 2016; Zemo et al. 2017), and some of them can persist for a long time. These partial degradation products, also known as metabolites, are termed petroleum HOPs in the ESLs as discussed in Section 4.1.3.

Thus, while biodegradation can reduce overall hydrocarbon mass and alter the composition of the vapor, water, and NAPL phases, the process results in new compounds with different exposure patterns and potentially altered toxicity characteristics for human and/or ecological receptors. As long as significant hydrocarbon mass remains at the site and conditions allow for biodegradation, HOPs will be continually generated (Bekins et al. 2016).

4.1.3 Petroleum Hydrocarbon Oxidation Products (HOPs)
The ESLs use the general term “petroleum hydrocarbon oxidation products” or “HOPs” for complex mixtures in the environment consisting of partially oxidized hydrocarbons generated during petroleum biodegradation. This term also includes photooxidation products of petroleum, which can be indistinguishable from microbially generated metabolites.

Other terms have been used to describe these petroleum breakdown products include polar compounds (in reference to their increased solubility), petroleum metabolites (in reference to their origin via biodegradation), petroleum degradates (terminology used in the 2016 ESL User’s Guide), or oxyhydrocarbons (term used sometimes in the literature).

The presence of one or more strongly electronegative oxygen atoms within the molecule increases the polarity of HOPs relative to the parent hydrocarbons and

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therefore their water solubility. This increased polarity facilitates dissolution into water at much higher concentrations compared to the parent hydrocarbons. For instance, concentrations as high as 40,000 µg/L bulk extractable TPH (TPHdiesel and TPH-motor oil) are not uncommon in groundwater near areas with significant petroleum contamination mass in soil (i.e., source or release areas).

Significant concentrations of HOPs likely indicate areas of anaerobic biodegradation, which can allow the buildup of these compounds because of slower anaerobic biodegradation rates (Jobelius et al. 2011).

Table 4-1 presents the physical-chemical properties of three HOPs and parent hydrocarbons, hexanoic acid and 2-hexanone, which are metabolites of nhexane, and 1H2NA, a metabolite of phenanthrene. As indicated, the HOPs can be significantly more soluble than the parent hydrocarbon. Moreover, the addition of oxygen into the structure can result in a significantly higher boiling point. For instance, n-hexane boils in the gasoline range, but one of its metabolites (hexanoic acid) boils in the diesel range, which has implications for interpreting bulk extractable TPH analytical results (e.g., misinterpreting the detection metabolites from gasoline biodegradation as being diesel range petroleum hydrocarbons). Most HOPs are relatively nonvolatile and not expected to partition into the vapor phase to a significant extent due to both their low volatility and high solubility.

Further information regarding these compounds and mixtures is provided in the technical memorandum Petroleum Metabolites: Literature Review and Assessment Framework (Regional Water Board 2016) and in TPH Risk Evaluation at Petroleum Contaminated Sites (ITRC 2018).

4.2 Approach to Evaluating Human Health Risks Posed by
Petroleum Releases
A comprehensive approach is recommended for evaluating human health risks posed by petroleum releases. The preferred approach evaluates multiple components, including individual chemicals, bulk petroleum hydrocarbons, and transformation products (HOPs), discussed herein.

4.2.1 Risk Assessment Challenges for Petroleum Releases The assessment of human health or ecological risks associated with petroleum releases is challenging because:
• Petroleum fuels and oils are complex mixtures, ranging from hundreds to thousands of compounds in some gasolines to tens of thousands of compounds in crude oils. The composition of the released mixture(s) is a key determinant of potential risks.

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• The composition of petroleum mixtures changes in the environment over time due to unequal loss of components through weathering processes (e.g., volatilization, dissolution, adsorption, biodegradation), and the rates of these processes vary based on site-specific characteristics. Moreover, biodegradation produces partial transformation products (HOPs) with different properties from hydrocarbons (e.g., more soluble). • It is impractical to analyze for hundreds or thousands of individual compounds.
• Even if it were practical to analyze for thousands of compounds, there are insufficient toxicity criteria for a compound-specific evaluation approach.

While a compound-specific evaluation approach is possible for the few toxicologically well-characterized petroleum hydrocarbons, there have been multiple efforts to devise an acceptable way to account for the risks posed by the bulk of hydrocarbon mixtures released into the environment. Various “TPH” methods were originally developed for quantitation and delineation purposes and some have been adapted for bulk risk evaluation.

4.2.2 Individual Chemicals
Three groups of individual chemicals can be found in oils or petroleum products, or are associated with petroleum releases:

1. Individual Hydrocarbons – Some chemicals in petroleum have been adequately characterized toxicologically, and regulatory toxicity values are developed for either their carcinogenic or noncarcinogenic effects (or both). For example, the TPH Criteria Working Group (1997a) identified approximately 250 individual hydrocarbon chemicals in various petroleum fuels and crude oils that have been studied. Of these 250 compounds, 95 had toxicity data but only 25 had sufficient data to develop toxicity criteria.

The individual chemicals in petroleum that are known carcinogens have been termed “indicator compounds” (e.g., TPH Criteria Working Group 1997a). These include benzene, ethylbenzene, naphthalene, and the seven carcinogenic PAHs (benzo[a]anthracene; benzo[b]fluoranthene; benzo[k]fluoranthene; benzo[a]pyrene; chrysene; dibenz[a,h]anthracene; and indeno[1,2,3,-cd]pyrene). These chemicals only make up a small percentage of the total composition of petroleum fuels/oils.

2. The most commonly analyzed individual hydrocarbons are benzene, toluene, ethylbenzene, xylenes and the 16 USEPA priority pollutant

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PAHs.4 The monoaromatics benzene, toluene, ethylbenzene and the three xylene isomers are commonly referred to as “BTEX.”

3. Performance Additives or Blending Agents – Nonhydrocarbon compounds have been added to various fuels for improving combustion performance, usually related to air quality. These agents have varied over time, seasons, regions, etc. For example, gasoline additives have included alkylated lead compounds (e.g., tetraethyl lead), lead scavengers (e.g., 1,2-dibromoethane also ethylene dibromide), oxygenates (methyl tertiary butyl ether or MTBE, tertiary butyl alcohol or TBA), and ethanol. Crude oils and other residual fuels (e.g., bunker fuel) may be blended for transportation or marketability purposes (e.g., pressure distillate added to crude oil to reduce viscosity and enable pipeline transport).

4. Other Chemicals Collocated with Petroleum Releases – Some chemicals have been documented to co-occur with releases of particular petroleum products or are known to be mobilized as a result of petroleum releases.

These include:
a. All hydrocarbons: Arsenic – A potential secondary effect of the natural attenuation of hydrocarbons coupled with iron reduction is a release of naturally occurring arsenic to groundwater (Cozzarelli et al. 2015). This phenomenon can occur where there is petroleum or other readily biodegradable organic carbon (e.g., naturally occurring or present in landfills). Arsenic plume migration can be limited by the presence of downgradient oxygenated conditions. b. Stoddard solvent: Tetrachloroethene (PCE) – Older or longoperating dry cleaners used the petroleum-based Stoddard solvent before the majority of the industry switched to chlorinated solvents.

Consequently, Stoddard solvent releases can be collocated with releases of chlorinated VOCs (e.g., PCE, TCE). Also, PCE was added to many dry-cleaning soaps used with petroleum solvents as a bacterial inhibitor, and TCE was often used for pre-treatment of stains (State Coalition for Remediation of Drycleaners 2009). c. Waste Oil: Chlorinated Solvents, Metals, and PCBs – At sites where waste oils were stored and released to the environment, such as former automotive service stations, constituents of potential concern can include chlorinated solvents (e.g., PCE,

4 Naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, benzo[g,h,i]perylene, indeno[1,2,3-c,d]pyrene, and dibenz[a,h]anthracene.

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TCE), select heavy metals (the wear metals cadmium, chromium, nickel, lead and zinc), and PCBs.

Table 4-2 lists potential individual compounds to consider for inclusion in a petroleum risk evaluation.

Table 4-2 – Potential Individual Chemicals of Concern for Different Petroleum Mixtures
Petroleum
Fuel or Oil
Benzene,
Toluene,
Ethylbenzene,
Xylenes, and
Naphthalene
(BTEXN)
Polycyclic
Aromatic
Hydrocarbons
(PAHs) 1
Additives 2 Other
Gasoline Yes -- Yes Arsenic (As)
Stoddard
solvent -- -- --
As, Chlorinated
Volatile Organic
Componds
(CVOCs)
Jet Fuel Yes -- -- As
Diesel Fuel Yes -- -- As
Motor Oil -- Yes -- As
Bunker Fuel -- Yes -- As
Crude Oil Yes Yes Yes As
Waste Oil
or
Unkown
Yes Yes Yes
Wear metals 3,
CVOCs,
Polychlorinated
biphenyls, As
Table 4-2 Notes: See Section 4.2.2 for further discussion.

Note 1 – PAHs are typically 16 priority pollutant PAHs, including naphthalene.

Other PAHs are addressed via the petroleum hydrocarbon mixture ESLs Note 2 – Additives – This is a general listing and is not intended to suggest that all of these compounds are present in a single fuel or release:
• Unleaded gasolines: oxygenates (Methyl tertiary butyl ether, Ethyl tertiary butyl ether, Tertiary butyl alcohol, Diisopropyl ether, Tertiary amyl butyl ether), methanol, ethanol.
• Leaded gasolines: alkylated lead (Tetraethyl lead), lead scavengers (1,2- Dibromoethane, 1,2-Dichloroethane).

Note 3 – Wear metals (cadmium, chromium, nickel, lead and zinc.

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Limitations of Single Chemical Petroleum Risk Approaches Reliance solely on a few individual chemicals for assessing human health risks and hazards from petroleum releases likely underestimates the total magnitude of adverse effects (HDOH 2012; Brewer et al. 2013; ITRC 2018). This is particularly true of sites where the chemicals being evaluated represent a small proportion of the mixture mass, were never part of the original released mixture(s) or have subsequently been depleted during weathering.

For example, a study performed by the Hawai’i Department of Health (HDOH 2012 and Brewer et al. 2013) found “The vapor intrusion risk (in general terms) posed by the non-specific, TPH component of petroleum vapors can override the risk posed by individual compounds such as benzene due to its overwhelming dominance of vapor phase compounds.” This finding is consistent with data collected at a number of petroleum hydrocarbon release sites in the San Francisco Bay Region, including former and existing automobile service stations, where staff has observed high concentrations of TPH-gasoline and low concentrations of benzene in soil gas samples. Therefore, when conducting risk evaluated at petroleum release sites, TPH data should be collected in the appropriate media (groundwater, soil, soil gas, and indoor air) in addition to the typically sampled individual chemicals (e.g., BTEX). The only meaningful way to identify the risk driver is to evaluate both and determine how the risks/hazards differ.

4.2.3 Petroleum Hydrocarbon Fractions
The risk from a mixture of petroleum hydrocarbons lacking regulatory toxicity criteria for most individual components can be evaluated using an approach based on petroleum hydrocarbon fractions and representative toxicity surrogates (MADEP 1994b; King et al. 1996; Washington DOE 1997; TPH Criteria Working Group 1999; ATSDR 1999; CCME 2008; USEPA 2009c; Atlantic PIRI 2012; Redman et al. 2014). Such an approach addresses the risk assessment challenges posed by petroleum releases (Section 4.2.1). Petroleum fractions are groups of hydrocarbons with similar molecular structures that have similar fate characteristics in the environment (e.g., volatility, solubility, susceptibility to biodegradation) and/or are considered to have similar toxicity. The use of a “petroleum fraction approach” with TPH fractionation analytical methods (e.g., Texas Method 1006) is the considered the best for assessing risk because the approach provides hydrocarbon quantitation aligned with toxicity values and physical/chemical parameters (Zemo 2016; ITRC 2018). The approach can be applied to any petroleum mixture found in the environment, and it accounts for weathering though it does not necessarily account for changes in bioavailability and toxicity of fractions that may result from weathering processes (TPH Criteria Working Group 1999). The use of the TPH fractionation analytical methods is described in Section 4.6.2.

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History of Petroleum Fraction Approaches
Two of the most widely cited early efforts to develop risk-based approaches to the evaluation of petroleum-contaminated sites using modifications to the bulk TPH analytical method were made by the Massachusetts Department of Environmental Protection (MADEP 1994b) and the TPH Criteria Working Group (1997a, 1997b, 1998a, 1998b, and 1999). These efforts focused on identifying groups of hydrocarbons with similar structure and environmental fate, termed “fractions,” and assigning physical/chemical parameters, toxicity values, and creating associated TPH “fractionation” analytical methods.

Other agencies have adopted similar fraction-based approaches, such as ATSDR (1999), Canada (CCME 2008; Atlantic PIRI 2012), Texas (TCEQ undated and 2001), Washington (Washington DOE 1997). In Europe, a similar approach called the “hydrocarbon block method” is used to assess whether the risks of petroleum mixtures in commerce are safe for intended uses (King et al. 1996; Redman et al. 2014).

In 2009, USEPA issued guidance for the Superfund Program adopting a fraction approach entitled Final Provisional Peer-Reviewed Toxicity Values for Complex Mixtures of Aliphatic and Aromatic Hydrocarbons (USEPA 2009c), based on the fraction approaches developed by MADEP and the TPH Criteria Working Group, which were considered to be reasonable, flexible, and the best available methodology for assessing risk from releases of complex hydrocarbon mixtures,.

USEPA scientists also evaluated the approach using computational chemistry and statistical methods and found supporting evidence for selecting the fractions (Wang et al. 2012). In recent years, the USEPA Regional Screening Levels have included TPH fraction screening levels (e.g., TPH aliphatic medium).

The USEPA petroleum fractions are divided by molecular structure into aliphatics and aromatics, and then each structure is subdivided into three carbon number ranges (low, medium, and high) for a total of six fractions. Figure 4-1 illustrates the six fractions based on hydrocarbon class and equivalent carbon number (EC).

Equivalent Carbon (EC) Number
The TPH Criteria Working Group (1998b) introduced the equivalent carbon (EC) number for calibrating the retention time or x-axis of the chromatogram, which represents boiling points, to read molecule size. Because the boiling point is also somewhat affected by chemical structure, the EC numbers are normalized to the boiling point of n-alkanes. Because of their polarity, aromatics boil at slightly higher temperatures than aliphatics with the same numbers of carbons. For example, using this scale, n-hexane (C6 normal or n-alkane) is EC6 where benzene (C6 aromatic) is about EC6.5.

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Surrogate chemicals or mixtures for which toxicity values can be obtained are selected to represent the toxicity of these fractions following an approach consistent with USEPA mixture risk assessment methods where dose-addition or response-addition is assumed (USEPA 1986, 2000e; see also Section 3.6.1).

USEPA selected surrogates for each fraction in the following order of preference (hierarchy):

1. Mixtures of similar composition

2. Representative compound in the fraction – Options include using the most toxic component if the toxicity varies considerably or the most abundant, if a component represents a large proportion of the fraction. In some cases, such as the medium carbon range aromatics, compounds with more potent toxicities (i.e., 2-methylnaphthalene) can be assessed separately while the remaining fraction mass is assessed using values for a surrogate mixture (i.e., high-flash aromatic naphtha).

3. Components Method – For fractions where the individual compounds are well characterized and with known toxicity values, the components are individually assessed.

Figure 4-1 – Diagram Illustrating the Petroleum Fractions in the ESLs by Equivalent Carbon Number (after USEPA 2009c)
ESL Fraction Approach
In 2013, the USEPA (2009c) petroleum fractions and associated toxicity values were selected for use in the ESLs for the following reasons: (1) the fraction approach is currently the best approach for evaluating potential risks posed by petroleum residues as evidenced by successful use of fraction approaches across multiple agencies within and outside the US; (2) the fraction approach is consistent with USEPA guidance on the health risk assessment of chemical

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mixtures (USEPA 1986 and 2000e); and (3) the surrogates and toxicity values are well supported in the seven provisional peer-reviewed toxicity value (PPRTV) documents (USEPA 2009b through 2009g and 2012e) and their selection is consistent with the ESL toxicity value hierarchy (Table 3-3) as there are neither OEHHA nor IRIS toxicity values for the petroleum fractions. Table 4-3 presents the fractions, designated as Fraction 1 through Fraction 6, and lists their partitioning characteristics.

Table 4-3 – ESL Petroleum Hydrocarbon Fractions and Partitioning Characteristics
Carbon (C)
Range Aliphatic Fractions Aromatic Fractions
Low
Fraction 1:

C5-C8 (EC5-EC8)
(Soluble & Volatile)
Fraction 4:

C6-C8 (EC6-EC<9)
(Soluble & Volatile)
Medium
Fraction 2:

C9-C18 (EC>9-EC16)
(Non-soluble & Volatile)
Fraction 5:

C9-C16 (EC9-EC<22)
(Soluble & Volatile)
High
Fraction 3:

C19-C32 (EC16-EC35)
(Non-soluble & Non-volatile)
Fraction 6:

C17-C32 (EC22-EC35)
(Non-soluble & Non-volatile)

4.2.4 Petroleum Hydrocarbon Oxidation Products (HOPs)
Petroleum hydrocarbon oxidation products (HOPs) are the partial transformation compounds of petroleum hydrocarbons generated through biodegradation (thus the commonly used name “metabolites”) as well as photooxidation. Increasingly, these polar transformation compounds and the mixtures in which they are found are being recognized as toxicologically relevant for a complete evaluation of both potential human health and ecological risks (Carney et al. 2008; Melbye et al. 2009; Bekins et al. 2016; Regional Water Board 2016b; Chibwe et al. 2015; Schrlau et al. 2017; Podgorski et al. 2018; McGuire et al. 2018).

Since the 2013 edition of the ESLs, HOPs (previously called polar compounds, metabolites or degradates) have been specifically included in the evaluation of petroleum sites to more comprehensively evaluate the potential adverse effects of hydrocarbon releases on human and ecological receptors. As explained in the 2013 and 2016 ESL editions, omitting the optional silica gel cleanup step from extractable TPH analyses permits the evaluation of both the parent hydrocarbons and portion of the HOPs together. In this 2019 edition of the ESLs, separate

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ESLs are developed for HOPs as described in Section 4.4. Laboratory analytical methods to measure HOPs are described in Section 4.5.3.

4.2.5 Selecting Chemicals of Potential Concern for Petroleum Releases
As discussed in preceding sections, a comprehensive evaluation of petroleum releases should include testing and evaluation for known or suspected individual chemicals, petroleum hydrocarbon mixtures and HOPs. These three categories comprise the generic chemicals of potential concern (COPCs) for petroleum sites. Table 4-4 shows how the three categories apply to various petroleum hydrocarbon mixtures.

Table 4-4 – Chemicals of Potential Concern for Petroleum Risk Evaluations Released
Petroleum
Hydrocarbon
Mixture
Individual
Chemicals
(Table 4-2)
Petroleum
Hydrocarbon
Mixture
Petroleum
HOPs
Gasoline Yes Yes Yes
Stoddard solvent Yes Yes Yes
Jet fuel Yes Yes Yes
Diesel Yes Yes Yes
Motor Oil Yes Yes Yes
Bunker fuel Yes * Yes
Crude Oil Yes * Yes
Unknown or
Waste Oil
Yes * Yes
Table 4-4 Note:
* – TPH fingerprint or TPH fractionation methods should be employed first to gain insight into the carbon chain range and composition. See Sections 4.3.5 or 4.6.2 for further information.

4.3 Calculation of ESLs for Petroleum Hydrocarbon Mixtures Unlike the RSLs, the ESLs do not include TPH fraction screening levels for separate aromatic and aliphatic fractions (e.g., TPH-aliphatic low). Such fraction43.734 2019 ESLs UG (Rev 0) 4-15
specific screening levels are not compatible with the routinely used bulk TPH analytical methods quantified against specific petroleum mixtures (e.g., gasoline, diesel). Such screening levels would necessitate the use of TPH fractionation analytical methods (e.g., Texas Method 1006) for all samples.

Noncancer ESLs for groundwater, soil, and indoor air are developed for five petroleum hydrocarbon mixtures: gasoline, Stoddard solvent, jet fuel, diesel, and motor oil (cancer risk is only evaluated for individual petroleum-related chemicals with regulatory cancer toxicity criteria such as ethylbenzene). These petroleum hydrocarbon mixture ESLs are intended for comparison against laboratory analytical results from the commonly used bulk TPH laboratory analyses (e.g., USEPA Method 8015B). This enables a screening-level risk evaluation. Further discussion on the use and limitations of the bulk TPH analytical method (e.g., use of silica gel cleanup, determination of background naturally occurring organic compounds, basic review of chromatograms) is provided in Section 4.5.

ESLs for the petroleum hydrocarbon mixtures are calculated using:

1. Petroleum fractions (Section 4.2.3) and properties (toxicity values and constants);

2. Proportions of the fractions expected in each medium:
a. Soil – unweathered fuels/oil composition
b. Indoor Air – proportions of the unweathered fuel/oil predicted to partition into vapor
c. Groundwater – proportions of the unweathered fuel/oil predicted to partition into water

3. USEPA RSL equations for calculating screening levels.

4.3.1 Petroleum Fraction Compositions for Each Petroleum Mixture Based on Medium
The proportion of each chemical fraction in a petroleum mixture (e.g., diesel) is used to develop medium-specific toxicity values in ESL Workbook Table IP-9, which is discussed in Section 4.3.3. After a release, petroleum hydrocarbon mixtures in the environment can be found at a site as either NAPL (soil), vapors (soil gas, crawl space air, indoor air, outdoor air), water (groundwater, surface water). The following subsections present the compositions of the fractions in the various petroleum hydrocarbon mixtures and partitioned components.

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Soil and NAPL Composition
Petroleum contamination in soil is indicative that NAPL has passed through the affected soil zone leaving some residual. For the petroleum mixture soil ESLs, the assumption is that the soil contamination is from NAPL. The composition of the released NAPL is used for developing soil-specific toxicity values for each mixture, as indicated in ESL Workbook Table IP-9.

Water and Vapor Compositions
The partitioning of hydrocarbons from fuels and oils is briefly described in Section

4.1.2 (Physical Weathering). The partitioning behavior of each fraction in water (solubility) and air (volatility) is taken into consideration as follows:
• Water –The soluble constituents of petroleum hydrocarbon mixtures are largely limited to aromatic hydrocarbon molecules with 14 or fewer carbon atoms (C14 and smaller), and smaller aliphatic hydrocarbon molecules with 6 or fewer carbon items (C6 and smaller) (Zemo and Synowiec 1995; ITRC 2018). The soluble fractions include Fraction 1 (low aliphatics), Fraction 4 (low aromatics), and Fraction 5 (medium aromatics). The fractionallysoluble petroleum mixtures for which ESLs are derived include Stoddard solvent, jet fuel, and diesel.
• Air – The volatile constituents of petroleum hydrocarbon mixtures are the C8 and smaller aliphatics and aromatics, with only minor amounts of C9- C12 aliphatics and aromatics (Hartman 1998; Brewer et al. 2013; ITRC 2018). The volatile fractions include Fraction 1 (low aliphatics), Fraction 2 (medium aliphatics), Fraction 4 (low aromatics), and Fraction 5 (medium aromatics). The fractionally-volatile petroleum mixtures for which ESLs are derived include Stoddard solvent, jet fuel, and diesel.

4.3.2 Petroleum Fraction Toxicity and Physical-Chemical Values
ESL Workbook Table IP-2 and Table IP-9 include noncancer ingestion and inhalation toxicity values for the six petroleum fractions developed by USEPA (2009c) as previously described in Section 4.2.3. ESL Workbook Table IP-9 also includes the Henry’s Law Constant for each fraction. Other physical-chemical property values (e.g., solubility) not based on the fractions but on the whole mixture are provided in ESL Workbook Table IP-1 with sources of values listed in the notes.

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4.3.3 Petroleum Mixture Toxicity Values and Henry’s Law Constants
Calculating ESLs using the standard USEPA equations requires the input of a single value for toxicity and Henry’s Law Constant (where needed). The mixtureand medium-specific toxicity value for each mixture (e.g., diesel for soil RfD) is developed using the fraction composition with one exception. For gasoline, Fraction 4 (low carbon range aromatic) is not used because the BTEX compounds are individually evaluated by testing for each compound. The proportions for the other five fractions for gasoline are normalized so the BTEX noncancer hazard is not counted twice.

The ESLs calculate weighted-average toxicity values and Henry’s Law Constants using a modified harmonic mean equation (Equation 3, from Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures; USEPA 2000e).

Weighted Average Value =
1 �
% F1
TV1 + % F2
TV2 +…+ % F6TV6 �
Where:

FX = Fraction X
TVX = Toxicity value for fraction X
(equation 3)
Each petroleum mixture’s medium-specific toxicity value (NAPL/soil RfD, watersoluble RfD, and air-volatile RfC; as shown in ESL Workbook Table IP-9) is weighted based on the relative proportion of each petroleum fraction in a given medium. This means that for NAPL/soil RfDs, the fraction weighting is based on weight percent composition in the bulk fuel mixture (NAPL). The water-soluble RfD is calculated only for the soluble (petroleum gasoline) and fractionallysoluble petroleum mixtures (petroleum Stoddard solvent, jet and diesel) based on the weight percent composition of the soluble fractions in the mixture. The airvolatile RfC is calculated only for the volatile (petroleum gasoline) and fractionally-volatile petroleum mixtures (petroleum Stoddard solvent, jet, and diesel) based on the weight percent composition of the volatile fractions in the mixture. Weighted-average Henry’s Law Constant values are calculated in a similar fashion as the toxicity values.

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4.3.4 Screening Levels for Other Mixtures
ESLs for other petroleum mixtures can be developed using the fraction approach provided there is information on the fraction composition (weighting) and partitioning (solubility and volatility).

4.3.5 Lack of ESLs for Crude Oils and Bunker Fuels
ESLs are not published for crude oils, bunker fuels because bulk TPH methods for these mixtures provide no useful information on the size of the carbon chains in the samples in addition to the limitations all bulk TPH analyses, which do not distinguish between hydrocarbon classes. Moreover, there are no typical crude oil or bunker fuel compositions and compositions span the low to high carbon range. Rather than a screening level evaluation, Regional Water Board staff recommends a site-specific evaluation using TPH fractionation analytical methods for crude oil and bunker fuel release sites (Section 4.6.2).

An alternative approach using bulk TPH analyses at a crude oil release site would be to analyze samples for TPH-gasoline, TPH-diesel, and TPH-motor oil and those analytical results can be used with the appropriate ESLs to calculate hazard quotients. Cumulative hazard index should then be evaluated. For a bunker fuel release site, analyze samples for TPH-diesel and TPH-motor oil, and those analytical results can be used with the appropriate ESLs to calculate hazard quotients. Cumulative hazard index should then be evaluated.

Should it be deemed necessary to conduct a screening level evaluation with existing bulk TPH-crude oil data, it is recommended each sample result be assumed to be composed of one-third each of TPH-gasoline, TPH-diesel, and TPH-motor oil. The data can then be used with the petroleum-gasoline, petroleum-diesel, and petroleum-motor oil ESLs to calculate hazard quotients.

Cumulative hazard index should then be evaluated. For a bunker fuel release site, the TPH-bunker sample results be assumed to be composed of one-half each of TPH-diesel and TPH-motor oil. The data can then be used with the petroleum-diesel and petroleum-motor oil ESLs to calculate hazard quotients.

Cumulative hazard index should then be evaluated.

Other approaches may be acceptable but should be determined in consultation with the overseeing regulatory agency.

4.3.6 Summary
The petroleum mixture screening levels provide a reasonably quantitative way to account for the toxic effects of the large number of petroleum chemicals in mixtures (i.e., chemicals not specifically studied for their toxicological effects)

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where exact quantification is not feasible. This option is recommended for screening-level evaluations because these screening levels can be compared against bulk TPH analytical method data (see Section 4.5). The primary limitation of this option is the screening levels only represent the compositions of example fresh fuels/oils. Different compositions of fuels/oils may result in different human health risks or hazards. In addition, the greater the weathering, the more the composition will deviate from fresh fuels/oils, which may also affect the risk estimate. An option for a more site-specific approach is presented in Section 4.6.2.

4.4 Calculation of Groundwater ESLs for Petroleum HOPs
Since the 2013 edition of the ESLs, Regional Water Board staff has recommended groundwater samples be analyzed using the extractable bulk TPH method both with and without SGC to enable consideration of the full effects of petroleum releases (both the hydrocarbons and polar transformation products, HOPs). In effect, this assigned HOPs the same toxicity values (both RfD and RfC) as hydrocarbons. Based on newer information, there is consensus that HOPs are not significantly volatile (ITRC 2018), particularly for the compounds with boiling points corresponding to C10 to C28 n-alkanes. Therefore, with inhalation exposure excluded, the tapwater ESLs for HOPs are less stringent than when they were grouped with the hydrocarbons. Also, the HOPs tapwater ESL is greater than the typical range of background natural organic compounds (NOCs) concentrations, reducing the likelihood of exceedances due to the presence of these naturally-occurring polar compounds unrelated to petroleum releases.

At this time, soil direct exposure ESLs for Petroleum HOPs have not been developed, although the rationale and approach would be similar to that for groundwater. In most of the cases where SGC has been used with extractable TPH analysis for soil samples, the results do not appear to be significantly different from extractable TPH without SGC. This may be due to a number of issues such as sorption of polar compounds to silica in the soil matrix, incomplete cleanup due to insufficient mass of silica gel, etc. The development of soil direct exposure ESLs for Petroleum HOPs is not a priority at this time but may be revisited in the future.

4.4.1 Petroleum HOPs Toxicity and Physical-Chemical Values The water RfD is selected based on the Petroleum Fraction 5 surrogate, highflash aromatic naphtha (2E-02 mg/kg-day). This is about the same boiling point range where most of the HOPs compounds are observed in the bulk extractable TPH analysis. No RfC is selected considering that most of these compounds are

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relatively nonvolatile (ITRC 2018). The rationale for applying the same RfD for hydrocarbons to that of the partial transformation products is:
• The toxic effects of many chemicals are mediated by their metabolites – For example, Pinto et al. (2016) found that metabolites from many types of chemicals have greater biological (estrogenic) effect than parent compounds. Another example is the metabolism of tetrachloroethene where the carcinogenicity increases as it breaks down to trichloroethene and vinyl chloride. Hydrocarbons also form toxic metabolites—examples include hexane and metabolite 2,5-hexanedione (IRIS) and anthracene and metabolite 9,10-anthraquinone (Zielinska-Park et al. 2004), which is also a photooxidation product (Mallakin et al. 1999). Moreover, toxicity testing of metabolite mixtures generated from microbial breakdown of phenanthrene, a relatively low toxicity PAH, found the metabolite mixtures to be more toxic than phenanthrene (Schrlau et al. 2017). • Results from toxicity testing of a naphthenic acid mixture suggest similar toxicity as the selected value (2.0E-02 mg/kg-day) – A dose-response study of naphthenic acids results in an RfD of 6.0E-02 mg/kg-day (see Regional Water Board 2016b), which is a factor of three difference from the selected value. Naphthenic acids are a complex mixture of carboxylic acids associated with petroleum. They occur in crude oil due to incomplete catagenesis or biodegradation in the environment.
• Recent studies of bioremediation effectiveness have found toxicity increased due to transformation products – Chibwe et al. (2015) employed targeted testing and effects-directed analysis (EDA)5 to assess the effectiveness of the bioremediation PAH-contaminated soils. Although the concentrations of the original 88 target PAH compounds were reduced after bioremediation, toxicity increased after bioremediation (metabolism).

The researchers concluded that focusing solely on a short list of target compounds and not considering transformation products does not

5 Effects-directed analysis (EDA) recognizes that environmental samples may contain thousands of organic chemicals and only a fraction can be analyzed by targeted chemical analysis (Brack 2003). Moreover, regulatory toxicity criteria are not available for the majority of these compounds. EDA utilizes biological effect to narrow down the long list of potential analytes and direct chemical analysis to those more likely to significantly contribute to effects. The approach includes biological testing and chemical fractionation in a sequential procedure. Elements of EDA are similar to USEPA Toxicity Identification Evaluations (USEPA 1991a; 1993b; 1993c).

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accurately capture the toxic effects of the partially degraded mixtures generated in environmental media.

Since the RfDs for parent hydrocarbon mixtures are based on limited numbers of compounds this approach is considered a reasonable approximation for metabolite-containing mixtures (HOPs).

The physical-chemical constants for HOPs are selected using 1-hydroxy-2- naphthoic acid (1H2NA; CAS 86-48-6) as a surrogate and values from the USEPA Estimation Parameter Interface Suite. 1H2NA is a known petroleum metabolite of phenanthrene (Kiyohara et a. 1994; Moody et al. 2001; Gao et al. 2013) and was detected in groundwater samples containing petroleum metabolites as reported in Zemo et al. 2017.

Although, in principle, this same approach is reasonable for soil, the generation of soil ESLs for HOPs is a low priority at this time.

4.4.2 Summary
We conclude that our approach for toxicity value assignment is consistent with USEPA guidance on chemical mixture risk assessment because of the implicit biological relationship between the parent compounds and their metabolites. As better scientific information becomes available (e.g., direct toxicity testing of HOPs mixtures), the RfD may be adjusted.

4.5 Laboratory Analytical Methods for Use with the Petroleum Mixture ESLs
The petroleum mixture ESLs are intended to be compared to sample concentrations measured with bulk TPH analytical methods (e.g., USEPA Method 8015C). This section presents background on the method and provides details for use of the bulk TPH methods and interpretation of the results to measure concentrations of petroleum hydrocarbon mixtures, petroleum HOPs, and determine NOCs levels.

4.5.1 Background: Bulk TPH Laboratory Method (USEPA
Method 8015B)
Total Petroleum Hydrocarbons (TPH) refers to a non-specific laboratory analysis that provides a measure of the concentrations of all chemicals with carbonhydrogen bonds (e.g., hydrocarbons, organic acids, chlorinated aliphatic hydrocarbons, etc.), present in a sample over a particular boiling point range

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(e.g., USEPA Method 8015C). The analysis does not measure only petroleum hydrocarbons, nor does it identify individual compounds. The TPH analysis will measure a mixture of many chemicals, thus use of the term “bulk.” The TPH analysis can be used, with adjustments described herein, to:
• measure petroleum hydrocarbon concentrations (Section 4.5.2), • estimate HOPs concentrations (Section 4.5.3), and
• determine background NOCs levels that can interfere with the bulk TPH analysis if the intent is to quantify hydrocarbons-only or HOPs (Section 4.5.4).

The term “bulk” also is used to distinguish between “whole product” methods (e.g., TPH-gasoline or gasoline range organics, GRO) versus TPH “fractionation” analytical methods that separate aliphatic and aromatic hydrocarbons and then measure their concentrations over smaller carbon ranges (e.g., EC10-EC12).

Use of TPH fractionation analytical methods for site-specific risk evaluations as an alternative to using petroleum mixture ESLs is discussed in Section 4.6.

Bulk TPH Method Description
Laboratory analysis for TPH in soil or groundwater samples is commonly applied in general accordance with USEPA Method 8015C Nonhalogenated Organics by Gas Chromatography (USEPA 2007a).

The key steps of TPH analysis are sample preparation/extraction, separation, and detection/quantification. Each of these steps has the potential for unequal recovery of sample constituents. Following extraction from an environmental sample with a nonpolar solvent (e.g., hexane or methylene chloride also known as dichloromethane), the sample is introduced into the GC where it is vaporized without decomposition and separated as the compounds travel through a single separation column. The column separates the compounds based on boiling point, with the more volatile compounds exiting the separation column first, followed by the less volatile compounds. After exiting, the compounds are analyzed in the attached detector. A flame ionization detector (FID) ionizes (burns) the carbon-containing molecules thus generating a signal proportional to the mass present in the sample. The results are plotted on a graph (chromatogram) with either boiling point or carbon number on the x axis and intensity of the response on the y axis. The concentration is determined by comparing the area under the sample peak/curve within a selected carbon range against the response from an unweathered fuel or oil standard.

The preparation methods differ for the more volatile mixtures (e.g. gasoline) and less volatile mixtures (e.g., diesel and motor oil):
• TPH-gasoline (gasoline range organics or GRO) – For gasoline-range compounds, TPH-gasoline is analyzed after a preparation step (e.g.,

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purge and trap, which is: USEPA Method 5030B for water samples, USEPA 1996h; and 5035 for soil samples; USEPA 1996i).
• TPH-diesel and TPH-motor oil (diesel range organics or DRO and motor oil range organics or MORO, respectively) – For diesel- and motor oilrange compounds, the TPH-diesel and TPH-motor oil analyses are usually performed after liquid-liquid extraction using dichloromethane, and then the extract is evaporated to concentrate the extract before analysis (USEPA Method 3510C, USEPA 1996f). The term “extractable TPH” refers to bulk TPH analytical methods employing an extraction step.

Further information is presented in the ITRC (2018) Fact Sheet A.2 TPH Analytical Methods.

Bulk TPH Method Limitations and Interferences
Bulk TPH analysis can measure many different organic chemicals. Interferences (nontarget compounds) vary depending on the sampling/measurement objective.

For example, if the objective is to measure only diesel-range hydrocarbons in groundwater for comparison to the petroleum-diesel groundwater ESL, then the measurement of HOPs or NOCs is an interference. On the other hand, if the objective is to measure HOPs concentrations in groundwater for comparison to the petroleum-HOPs groundwater ESL, then the measurement of hydrocarbons or NOCs is an interference.

Use of Silica Gel Cleanup (SGC) to Remove Nonhydrocarbons This section describes silica gel and its uses.

What is Silica Gel?
Combining silicon dioxide (SiO2) with 2 H2O produces silica gel, a solid with many –OH groups that can interact with polar chemicals. The more polar a chemical, the tighter it binds to Si(OH)4.

Uses for Silica Gel
Silica gel is often used as a drying agent to remove water. Chemists use it to separate more polar from less polar compounds. It has two principal applications in TPH analysis:

1. Removing polar compounds from petroleum mixtures that were extracted with a nonpolar solvent. This is called “silica gel cleanup” (SGC). It removes most of the polar natural organic compounds and HOPs and leaves most of the hydrocarbons.

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2. Separating aromatic from aliphatic hydrocarbons as part of fractionation.

As described in the MADEP extractable phase hydrocarbon procedure, the procedure requires great care so that the aromatics do not end up in the wrong fraction. (MADEP 2004b).

Use of Silica Gel Cleanup with the Bulk Extractable TPH Analysis The use of a column silica gel cleanup (SGC; USEPA Method 3630C; USEPA 1996g) is an optional procedure that can be added to the bulk extractable TPH analysis, for additional cost. Using SGC will remove polar compounds including HOPs and NOCs. Extractable TPH results after SGC will only measure hydrocarbons. SGC cannot be used for volatile hydrocarbon analysis because the procedure would volatilize the target hydrocarbons. Further information is presented in the ITRC (2018) Fact Sheet A.5 Silica Gel Cleanup.

Data Interpretation: Basic TPH Chromatogram Review
Due to the non-specific nature of the bulk TPH analysis, bulk TPH analytical data are best interpreted considering the CSM and available lines of evidence. Lines of evidence that are most useful include knowledge of the type of fuel/oil released, location of the sample relative to the release area (e.g., downgradient), bulk extractable TPH analysis both with and without SGC, understanding of partitioning (hydrocarbons, HOPs), and chromatogram shape/pattern. For instance, the chromatographic pattern and spatial relationship to the release (source) area can be used to help distinguish the source of polar nonhydrocarbons (HOPs and NOCs) in sample (Zemo 2016).

The purpose of a basic chromatogram review is to confirm that the compounds being detected are the intended target compounds rather than interferences.

Chromatograms, even from bulk TPH analysis, can provide information on fuel/oil type, presence of nonhydrocarbons (e.g., HOPs, NOCs, other chemicals like solvents), whether the material is dissolved or not, and degree and type of weathering (ITRC 2018). Chromatograms should be obtained and reviewed during the investigation phases of a project. Similarly, chromatogram review may be warranted prior to key decisions or when results are not consistent with the CSM/previous testing.

Scaled chromatograms of the samples, standards, and blanks should be obtained from the laboratory and included in technical reports. The chromatograms’ x axis (retention time or elution time of indicated n-alkanes) should be the same scale for all chromatograms to facilitate comparison and interpretation. The y axes will necessarily vary for each sample/standard/blank depending on the intensity of the detector response (i.e., relative concentration).

Chromatogram review is performed by comparing the sample to the standard chromatogram as illustrated in Figure 4-2. The compounds detected in the groundwater sample were determined to be petroleum HOPs only based on the following lines of evidence: (1) the detected compounds are polar because after

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SGC the results were non-detect; (2) the chromatogram pattern is typical of petroleum HOPs (literature examples of HOPs include Lundegard and Sweeney 2004 and Lang et al. 2009, described as weathered petroleum or polar compounds); (3) spatial relation to the petroleum release area (downgradient); and (4) non-detect background concentrations of NOCs.

Figure 4-2 – Example of Basic Petroleum Chromatogram Review for HOPs.

This figure illustrates the comparison of a chromatogram for a groundwater sample containing petroleum HOPs against a chromatogram for a diesel fuel standard. Note the HOPs UCM is shifted to the right (higher apparent EC number) compared to diesel standard. The tall peaks are lab standards used for quality control purposes. The background groundwater sample contains 27 µg/L NOCs (TPH-diesel without SGC).

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Example chromatograms of petroleum and non-petroleum containing products or samples are provided in a number of articles or guidance documents:
• Fresh and weathered petroleum in soil and groundwater – Zemo et al. 1995; Zemo 2016; ITRC 2018 (Appendix A5 – Chromatograms: A Wealth of Information).
• HOPs – Lundegard and Sweeney 2004; Lang et al. 2009; Zemo 2016; and Figure 4-2.
• NOCs – Regional Water Board staff have observed these compounds in chromatograms primarily as single peaks.

When reviewing chromatograms from water samples, it is important to bear in mind the fuel/oil standards are dissolved in organic solvents and therefore the chromatographic pattern should not resemble the standard due to differential partitioning of individual compounds from a mixture into water. Figure 5a of Lang et al. (2009) provides a chromatogram illustrating single peaks indicative of dissolved hydrocarbons from fresh diesel.

4.5.2 Measuring Hydrocarbons using the Bulk TPH Analytical Method
Petroleum hydrocarbon mixtures can be detected and quantified using the bulk TPH analyses. The TPH-gasoline analysis is performed without SGC because the process would volatilize hydrocarbons in the sample (ITRC 2018). The extractable range hydrocarbon mixtures (e.g., petroleum-Stoddard solvent, jet, diesel, and motor oil) is performed after SGC because the intent is to measure only hydrocarbons, so the nonhydrocarbons are considered non-target compounds and can be removed.

4.5.3 Measuring HOPs using the Bulk Extractable TPH Method HOPs can be detected and reasonably quantified by the bulk extractable TPH analysis to some extent, but not if SGC is used. The bulk extractable TPH analysis appears to be the best method currently available for estimating HOPs concentrations because the chromatogram pattern can be used to confirm the types of compounds measured. Laboratory analytical reports should include scaled chromatograms from samples, standards, and blanks. For the best identification and quantitation of HOPs using available methods, Regional Water Board staff recommends the use of a bulk extractable TPH analysis quantified against a diesel standard over the carbon range C10 to C28. A less preferred alternative is to analyze for both TPH-diesel and TPH-motor oil (non-overlapping

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ranges) and add the results. The estimated HOPs concentration is determined via the equation 4 below and illustrated on Figure 4-3. [HOPs] = [Total Hydrocarbon] – [PHC] – [NOCs]
Where:
[ ] = Concentration
[Total Hydrocarbon] = Plume sample measured with TPH-diesel C10-24 without SGC
[PHC] = The same plume sample measured with TPH-diesel C10-28 with SGC
[NOCs] = Sample from an unimpacted (background) area with similar vegetative and hydrogeologic characteristics as plume sample (see Section 4.5.4) measured with TPH-diesel C10-28 without SGC
(equation 4)
Figure 4-3 – Conceptual Plume Map Showing How to Estimate Petroleum HOPs Concentrations
HOPs detected in groundwater samples using the bulk extractable TPH analysis typically manifest in the chromatogram as an unresolved complex mixture (UCM or hump) in the C15 to C28 range (Lundegard and Sweeney 2004; Lang et al. 2009; see also Figure 4-2). Due to the presence of oxygen in the structure, HOPs have higher apparent EC numbers than expected (see Section 4.1.3). Regional

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Water Board staff has frequently observed the UCM straddling the diesel and motor oil ranges for groundwater samples analyzed without SGC for TPH-diesel over C10-C24 and TPH-motor oil over C24-C36 (Figure 4-2). At older petroleum release sites, it is not uncommon to observe a polar UCM starting at about C12 to 14 (based on n-alkane boiling points) and extending into the low C30s, with the UCM apex between about C17 to C21.

Method Limitations
Bulk TPH analytical methods have shortcomings for detecting polar compounds such as HOPs. In a study of two crude oil spill sites, the USGS found that the extracted diesel-range organic compounds represent one-third to one-half of the total concentration of HOPs found in groundwater (Bekins et al. 2016). The USGS determined the main reasons for the difference resulted from the following three aspects:
• Polar compounds do not extract well in nonpolar organic solvents like methylene chloride or hexane (TPH Criteria Working Group 1998a), the solvents typically used for EPA Method 3510C (USEPA 1996f). • Many polar compounds are not amenable to gas chromatography (GC); they do not readily pass through the GC column without derivatization (TPH Criteria Working Group 1998a), thus, important compounds of interest may be retained in the column.
• The narrow boiling point range of the TPH-diesel method (e.g., C10 to C24) means that some HOPs will not be measured. Some HOPs are above or below this range. As noted above, UCMs often extend beyond C24.

These limitations could result in a situation where HOPs are present but are not detected (Figure 4-4). Consequently, the extractable TPH analysis underestimates HOPs concentrations and better methods are needed.

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Figure 4-4 – Illustration of the Key Shortcoming with the TPH-diesel (also “diesel-range organics” or “DRO”) Analysis for Measuring Petroleum HOPs Concentrations.

Figure 4-4 illustrates that a sample near the downgradient portion of a plume may be non-detect for TPH-diesel when petroleum HOPs are actually present.

NVDOC is non-volatile dissolved organic carbon, an analytical method used by the US Geological Survey at the light crude oil release research site in Bemidji Minnesota. Upgradient background NOCs levels were non-detect for DRO without SGC and 1,500 µg/L NVDOC. Source: Bekins and Cozzarelli (2017).

4.5.4 Determining Background Levels of Natural Organic
Compounds (NOCs)
In addition to HOPs, there are naturally-occurring organic compounds resembling hydrocarbons with polar functional groups, which we refer to as natural organic compounds (NOCs). These polar compounds are considered interferences to bulk TPH analyses where the intent is to measure only HOPs concentrations (Section 4.5.3).

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Determination of background concentrations of NOCs can be performed by collecting samples in an area of the site with no known petroleum release and with a similar hydrogeologic and vegetation setting. While an upgradient location may be deemed ideal, cross-gradient or downgradient locations are equally acceptable if the hydrogeologic and vegetative setting is similar. Based on staff experience, concentrations of NOCs using bulk extractable TPH analysis typically are in low 100’s of µg/L range, rarely exceeding 300 µg/L. Consultation with the overseeing regulatory agency is recommended before implementing a background testing program.

Near petroleum release areas (i.e., source areas), the concentrations of HOPs typically far exceed the concentrations of NOCs (Zemo and Foote 2003; Zemo et al. 2013), and the potential for significant interference from NOCs is negligible.

However, during an initial investigation, when interpreting whether extractable TPH concentrations reflect a petroleum release, NOCs, or both, estimating the relative contribution of NOCs can be important.

The NOCs can manifest in the chromatogram as single peaks that do not resemble a UCM, and so chromatogram review can, in some cases, be a useful tool.

4.5.5 Recommended Bulk TPH Analyses for Soil and
Groundwater Samples
Table 4-5 lists the recommended bulk TPH analyses, carbon range, and whether SGC use is appropriate for each petroleum mixture in the ESLs. Table 4-5 also provides recommendations for bunker fuel, crude oil, and unknown or waste oil mixtures. Bulk TPH analyses for wide carbon ranges (e.g., bunker fuel and crude oil) are not recommended as discussed in Section 4.3.5; instead TPH fractionation methods are recommended. Much less preferred would be to analyze for bulk TPHg, TPHd, and TPHmo. Similarly, for unknown fuels/oils or waste oil, a TPH fractionation approach is preferred, with the less preferred alternative being analysis for bulk TPHg, TPHd, and TPHmo.

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Table 4-5 – Bulk TPH Laboratory Analysis for Soil and Groundwater Samples
Target Petroleum
Mixture
Recommended
Bulk TPH
Analytical Methods1
(USEPA Method
8015B)
Use of Silica Gel
Cleanup
(USEPA Method 3630)
Gasoline TPHg (C5 to C12) Cannot use2
Stoddard solvent TPHss (C7-C12) Cannot use2
Jet Fuel TPHj (C9-C16) Can use
Diesel TPHd (C10-C24) Can use
HOPs TPHd (C10-C28) 3 Cannot use
Motor Oil TPHmo (C24-C36) Can use
Bunker Fuel (C12-C40),
Crude Oil (C5-C44),
Unknown, Waste Oil
Note 4 Note 4
Table 4-5 Notes:

Note 1 – Compositions may vary from these ranges.

Note 2 – SGC cannot be used. The procedure will volatilize the target hydrocarbons.

Note 3 – HOPs typically elute at boiling points between the boiling points of C10 to C28 n-alkanes. The concentration of HOPs is not directly measured but is estimated via subtraction as described in Section 4.5.3.

Note 4 – Bulk TPH analyses for wide carbon range fuels or oils are not recommended because they provide limited information for evaluating risk.

Instead, TPH fractionation analyses are recommended. Further information is presented in Sections 4.3.5 and 4.2.6.

4.5.6 Recommendations for Vapor Analyses
At sites where significant contaminant mass remains and/or where other unique conditions prevent adequate aerobic biodegradation (e.g., geochemical conditions, preferential pathways, building susceptibility, significant pressure gradients), TPH vapors can drive risk (Brewer et al. 2013). Laboratory analysis of vapor samples (indoor air and soil gas) for TPH can be performed in accordance with the USEPA Methods TO-3, TO-15, or TO-17. Based on Brewer et al. (2013), the following are recommended for the analysis of TPH vapors:

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• Low and medium carbon range hydrocarbons – TPH vapors quantified from C5 to C12 against a gasoline standard in accordance with USEPA Method TO-15 or equivalent.
• Medium carbon range hydrocarbons – TPH vapors quantified from C12 to C18 against a diesel standard in accordance with USEPA Method TO-17 or equivalent (note that TO-17 is a sorbent tube sampling method).

The analysis of TPH vapors most often will be performed for the evaluation of the vapor intrusion pathway. Including the analysis for fixed gases (oxygen, carbon dioxide, and methane) is recommended to enable an adequate evaluation for petroleum vapor biodegradation and vapor intrusion (see Chapter 5). ASTM Method D-1946 is one method commonly employed for fixed gases analysis.

4.6 Site-Specific Human Health Risk Evaluations for
Petroleum Mixtures
This chapter supplements the site-specific risk evaluations (Section 3.7) by addressing specifics of risk evaluation at petroleum release sites, which involve complex mixtures that change in space and time after release to the environment. In general, the options for site-specific risk evaluations discussed in Section 3.7 also apply to petroleum risk evaluations.

Section 4.2 identified the three components associated with petroleum releases:
individual chemicals, petroleum fractions, and HOPs. Screening-level risk evaluations can be employed for all three components using the ESLs (Section 4.6.1). Tier 2 or Tier 3 risk assessments can be performed for the individual chemicals and the petroleum fractions (Section 4.6.2).

Alternative approaches will be considered, provided there is adequate technical justification. For regulatory review, either a detailed work plan should be submitted, or a thorough scoping meeting conducted, before completing the evaluation or submitting a report of findings. This important step reduces the likelihood of unnecessary and costly work and greatly improves the likelihood of regulatory concurrence.

4.6.1 Screening Level Evaluations Using the Petroleum
Mixture ESLs
Section 4.2 identified the three components associated with petroleum releases:
individual chemicals, petroleum fractions, and HOPs. Screening-level risk evaluations can be employed for all three components using the ESLs. For the petroleum mixtures, screening level evaluations rely on comparison of bulk TPH data to the appropriate petroleum mixture ESLs.

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4.6.2 Site-Specific Human Health Risk Evaluations of
Petroleum Hydrocarbons: TPH Fractionation Methods
Tier 2 or Tier 3 risk assessments can be performed for the individual chemicals and the petroleum fractions at sites where petroleum mixtures were released.

Such site-specific evaluations for petroleum hydrocarbon mixtures can include development of site-specific screening levels or site-specific risk assessments provided adequate testing is performed to estimate the petroleum fraction compositions throughout a site. This necessitates the use of TPH fractionation analytical methods.

TPH fractionation methods separate hydrocarbons into aliphatics and aromatics and measure concentrations for specific carbon number ranges. Separation into aliphatics and aromatics is often accomplished by silica gel solid-phase extraction/fractionation processes.
6 Fractionation methods differ for soil and
water samples versus vapor samples. The advantages of TPH fractionation methods are: (1) the method overcomes the need to know the type of fuel/oil released; and (2) accurate measurement of the hydrocarbon types and concentrations over narrow carbon ranges addresses composition changes due to weathering.

Figure 4-5 illustrates the carbon ranges for bulk TPH and TPH fractionation analytical methods. Each color represents a single laboratory analytical method.

The bulk TPH methods are illustrated for the ESL petroleum hydrocarbon mixtures and other mixtures (crude oil and bunker fuel). TPH fractionation methods recommended in Zemo (2016) also are illustrated. As shown, significantly greater composition information is provided by a TPH fractionation method (e.g., Texas Method 1006) as contrasted with the bulk TPH-crude oil analysis.

Three state agencies have developed TPH fractionation methods:
• MADEP – Volatile Petroleum Hydrocarbons (VPH) and Extractable Petroleum Hydrocarbons (EPH) for soil and water (MADEP 2004a and 2004b). Air Phase Hydrocarbons (APH) MADEP (2009).
• TCEQ – Method 1006 (TCEQ 2000).
• Washington Department of Ecology (WDOE) – VPH and EPH for soil and water (WDOE 1997)

6 Because silica gel is employed in the fractionation methods, petroleum metabolites will be lost (removed) and will have to be separately assessed via the bulk extractable TPH analysis or other suitable methods.

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The TCEQ and WDOE TPH fractionation methods are generally recommended for soil and groundwater samples. The MADEP Air Phase Hydrocarbons method is generally recommended for vapor samples. The document “White Paper:

Analytical Methods for Total Petroleum Hydrocarbons (TPH)” (Zemo 2016) is a helpful reference that compares and contrast different TPH methods, including both Bulk TPH and TPH Fractionation methods.

For petroleum sites under Regional Water Board staff oversight where a sitespecific risk evaluation using TPH fractionation data is selected over a screening level evaluation, it will be necessary to develop and submit a work plan to adequately characterize petroleum fraction compositions and conduct a risk evaluation.

Issues that should be addressed in the work plan include, but are not limited to the following:
• Proposed TPH fractionation analyses description and rationale • Given that the USEPA petroleum fractions carbon ranges are not matched with TPH fractionation methods, describe and provide justification for how the data will be aggregated to determine fraction concentrations and hazards.

A similar type of fraction or fractionation evaluation is not currently possible for HOPs, so evaluation of HOPs using the ESLs is limited to screening level evaluations.

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Figure 4-5 – Example Carbon Ranges for Bulk TPH and TPH Fractionation Laboratory Analyses

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5 Methods: Vapor Intrusion Risk
Screening Levels for Groundwater and
Subslab/Soil Gas
The vapor intrusion (VI) ESLs account for potential human health risk from exposure to contaminated indoor air caused by contaminated subsurface media (groundwater, soil, soil gas). Consequently, the VI ESLs represent an indirect exposure pathway because the media (groundwater and soil gas) are not the exposure medium, which is indoor air. The two general receptors considered for such exposure are residents and indoor commercial/industrial workers. VI ESLs are developed in two ESL Workbook Tables: GW-3 (groundwater) and SG-1 (soil gas7). These ESLs apply to existing and future buildings.

In general, the VI ESLs are not used at sites that are subject to the Low-Threat Underground Storage Tank Closure Policy (LTCP; State Water Board 2012b).

Specifically, the LTCP does not the use the ESLs to screen contaminants at petroleum-contaminated sites. Instead the LTCP provides closure levels for carcinogens and general (narrative) criteria. ESLs may be used at sites with “unique attributes” to screen for constituents not already addressed by the LTCP.

5.1 Background
Use of the VI ESLs is consistent with the Regional Water Board’s approach to chlorinated VOC vapor intrusion (CVI), which is described in the TCE Framework (Regional Water Board 2014). Other relevant guidance includes the DTSC Vapor Intrusion Guidance or VIG (DTSC 2011b) and the OSWER VI Guide (USEPA 2015a).

5.1.1 Conceptual Model for Vapor Intrusion into Buildings The conventional model for VI consists of contaminated vapor transport through bulk soil (a porous medium) into a building. Over the last decade, an alternative pathway has been recognized as another important VI mechanism: contaminated vapor transport through sewer or utility conduit airspace into buildings (McHugh and Beckley 2018b). Researchers have found that sewer lines potentially are either the primary or a significant contributing pathway for about 20 percent of VI sites (McHugh et al. 2017b). Both conceptual models for VI are described below.

7 Soil gas, as used in the ESLs, includes both exterior/deep soil gas and subslab soil gas (or subslab), which is a soil gas sample collected immediately beneath the base of the foundation).

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The VI ESLs address the conventional model for VI; Section 5.1.5 and Section

5.4.1 discuss how to evaluate vapor conduit pathways (e.g., sewer and utility conduit air).

Conventional Model for Vapor Intrusion
There are four components to the transport of contaminated subsurface soil gases through bulk soil into buildings: 1) partitioning from the VOC source (groundwater or soil) into the vapor phase; 2) primarily diffusive vapor transport through the subsurface from the VOC source toward the building; 3) vapor entry primarily via advection into the building; and, 4) mixing with air inside a building (Figure 5-1)
Near contaminant release areas (i.e. the area of vadose zone soil contamination that extends from a source), VOC vapors can be emitted from both the impacted vadose zone soil and groundwater. However, away from release areas, the VOC vapor source is typically groundwater. VOC vapor concentrations will decrease (or attenuate) as VOCs diffuse upward and laterally away from a vapor source.

The amount of vapor attenuation will depend on both subsurface characteristics (e.g., moisture content, soil type), surface characteristics (e.g., type of material or structure covering the ground surface) and weather conditions that influence the air exchange between a VOC vapor source and the ambient air.

Less attenuation is expected beneath buildings with a slab (e.g., slab-on-grade or basement) due to the “slab capping effect,” where a concrete slab acts as a barrier or cap limiting the downward flow of ambient air and the upward venting of contaminated soil gas (Figure 5-2) (Schumacher et al. 2010; Shen et al. 2014).

In general, the slab capping effect increases as the area of a slab increases (e.g., larger buildings) or as the permeability of a slab decreases (e.g. thicker slabs). When slab capping effects are significant, VOC soil gas samples collected just above the vapor source (commonly referred to as “near-source soil gas”) typically correlate better than shallow exterior soil gas samples with subslab soil gas (Figure 5-2 A; DTSC, 2011b; USEPA, 2012a and 2015a). When predicting worst case subslab soil gas concentrations coming from a deep groundwater (> 20 ft bgs) vapor source, soil gas samples at roughly 15 ft bgs should be deep enough to account for slab capping effects (Figure 5-2 B). For buildings where slab capping effects are not expected (e.g., crawl space foundations with dirt floors), shallower exterior soil gas samples may be sufficient to predict soil gas concentrations directly beneath the building.

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Figure 5-1 – Conventional Conceptual Model for Vapor Intrusion Source: McHugh et al. 2017b
For a groundwater VOC vapor source, diffusion first occurs through the capillary fringe, which has high moisture content and low air content. Consequently, groundwater VOC sources are subject to much greater attenuation than vadose zone soil VOC sources (McCarthy and Johnson 1993). Furthermore, the thicker the capillary fringe, which is generally controlled by grain size (fine-grained soils such as silts and clays have thicker capillary fringes than coarse-grained soils such as sands and gravels), the greater the overall resistance to vapor transport.

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Figure 5-2 – Slab Capping Effect and Soil Gas Sampling Locations Best Representing Concentrations in Contact with a Building Foundation Source: USEPA 2012a.

Conceptual Model for Sewer/Utility Conduit Air VI
Recent technical literature has recognized the importance of high-capacity preferential pathways for transporting contaminated vapors into buildings (vapor conduit pathways), such as sewer lines and utility conduits (Pennell et al. 2013; Guo et al. 2015; McHugh et al. 2017a and 2017b; McHugh and Beckley 2018a, b, and c). VOCs may enter sewer pipes that intersect contaminated soil or groundwater. Once inside the sewer pipe, VOCs can be transported beneath or directly into the building (Figure 5-3). While sewer plumbing systems inside buildings are designed to prevent sewer gases from entering the building, many components of sewer systems leak or become compromised. The locations where contaminated vapors from these pathways can enter buildings are variable. Examples include cracked or punctured pipes, loose fittings or degraded gaskets, dry plumbing traps (e.g., p-traps), diffusion through stagnant p-trap water, or via building foundation drains. Due to greater void space in the pipe, vapor transport typically is greater than the backfill (porous media).

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Figure 5-3 – Conceptual Model for the Sewer Air Vapor Intrusion Pathway Source: McHugh et al. 2017b.

5.1.2 Multiple Lines of Evidence (MLE) Approach to
Evaluating Vapor Intrusion
Evaluating the VI pathway can be challenging due to:
• Numerous factors affecting the extent to which contaminant vapors migrate from the subsurface into overlying buildings (e.g., subsurface geology, building design, and climate conditions).
• Levels of volatile chemicals in background air (from outdoor or indoor sources) that can confuse or confound the use of indoor air results to detect and measure contaminated vapors emitted from subsurface releases.
• The considerable uncertainty associated with individual lines of evidence resulting from the spatial and temporal variability of volatile contaminant concentrations in groundwater, soil gas (including subslab soil gas), and indoor air (Holton et al. 2013; Winkler et al. 2001).

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Consequently, evaluation of potential VI necessitates a multiple lines of evidence (MLE) approach to reduce uncertainties and increase confidence in making site management decisions. Each line of evidence (LOE) is evaluated, weighted, and the degree of concordance with the CSM assessed. Use of a single LOE to screen a site out from further review is generally not appropriate.

The following basic principles apply for evaluating LOEs:
• Using LOEs to Develop and Maintain the CSM – Information from each LOE should be used to inform the CSM and the CSM should be revised as LOEs are added or conflicting LOEs are resolved.
• Weighting LOEs Based on Proximity of Sample Medium to the Receptor – Typically, the closer the sampled medium is to the receptor, the greater those data are weighted. However, this does not negate the need to consider and weigh LOEs based on their quality and representativeness. • Minimum Number of Sample Medium Data LOEs for Decision Making – Reliance on a single sample medium data LOE (e.g., groundwater or soil gas sample data) generally is not considered adequate. In most cases at least two concordant sample medium data LOEs are necessary for a complete VI evaluation. When different sample medium data LOEs conflict, additional LOEs should be considered such as, continued temporal monitoring to better resolve a data LOE, or increasing data density.
• Limitations of LOEs – Each LOE should be weighed based on an understanding of its limitations (e.g., variability, data quality). For instance, subslab soil gas concentrations typically shows spatial and temporal variability. Therefore, reliance on a single subslab soil gas sample from a single sampling event would introduce significant uncertainty into a site management decision.

5.1.3 Lack of VI ESLs for Soil
The 2005 ESLs were the last edition with soil levels for VI concerns.

Subsequently, the Regional Water Board discontinued publishing soil ESLs for VI concerns due to the uncertainty associated with the partitioning equations and the potential loss of volatile organic compounds (VOCs) during sample collection, preservation, and analysis (DTSC 2011b; USEPA 2014c, USEPA 2015a). Loss of VOCs from soil samples in this manner is a particular concern in samples collected before use of USEPA Method 5035 (e.g., DTSC 2004) for field preservation. For these reasons, soil matrix data are not considered a primary LOE and should never be used as the sole LOE for assessing VI. Moreover, VOC concentrations of soil samples collected before use of USEPA Method 5035 (e.g., DTSC 2004) for field preservation, likely are biased low. However, soil samples may be necessary for evaluating direct exposure concerns and can be helpful for estimating the release area (i.e., the area of vadose zone soil

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contamination that extends from a source). Determining the location and extent of all release areas is a critical LOE for a complete CSM and vapor transport assessment.

5.1.4 Lack of VI ESLs for Crawl Space Air
VI ESLs for crawl space air are not published; instead crawl space air samples can be compared directly to the indoor air ESLs. A crawl space to indoor air AF of 1 should be used when calculating risk for screening. USEPA found little attenuation between crawl space air and indoor air. USEPA concluded that air exchange between the crawl space air and indoor air leads to approximate equilibration in air concentrations within the two spaces (USEPA 2012c).

5.1.5 Lack of VI ESLs for Sewer/Utility Conduit Air
VI ESLs for sewer or utility conduit air (vapor conduit pathway) are not published.

Regional Water Board staff recommends the use of the sewer/utility air-to-indoor air AF of 0.03 as recommended in Sewers and Utility Tunnels as Preferential Pathways for Volatile Organic Compound Migration into Buildings: Risk Factors and Investigation Protocol (McHugh and Beckley 2018b). Divide the human health based indoor air ESLs by 0.03 to generate sewer/utility air-to-indoor air screening levels; practically speaking, these values are the same as the subslab/soil gas ESLs. See Section 5.4.1 for information regarding how to evaluate the vapor conduit pathway.

5.2 Calculation of Soil Gas and Groundwater VI ESLs
A chemical is considered volatile if either: (1) the vapor pressure is greater than 1 millimeter of mercury or (2) the Henry’s Law Constant is greater than 1x10-5 atmospheres-cubic meter/mole (USEPA 2015a). The calculation of soil gas and groundwater VI ESLs relies on the Indoor Air ESLs (Excel Workbook IA-1, described in Chapter 3) and the development of vapor attenuation factors as described herein.

5.2.1 Vapor Attenuation Factors
Vapor attenuation refers to the reduction in volatile chemical concentrations during gaseous transport from the subsurface to indoor air. The attenuation factor (AF) is a measure of this reduction. AFs are calculated differently for soil gas and groundwater as described as follows.

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Soil Gas to Indoor Air Attenuation Factor
The equation for the soil gas AF (equation 5), which applies to both subslab soil gas (subslab) and exterior/deep soil gas, is shown below. This AF can be used to predict VI at all buildings, regardless of design or use (e.g., crawl space, slab-ongrade, residential, or commercial).

AFSG =
CIA
CSG
where:

CIA = Indoor air concentration in µg/m3
CSG = Soil gas (subslab and deep/exterior soil gas) concentration in µg/m3 AFSG = Attenuation factor for all soil gas (subslab and deep/exterior soil gas) (unitless)
(equation 5)
Therefore, the AF is an inverse measurement of the concentration reduction (attenuation) of a volatile chemical that occurs during subsurface transport to indoor air. For instance, an AF of 0.03 corresponds to a 33-times reduction in concentration: AF = 1/concentration reduction = 1/33 = 0.03. Larger AFs correspond to less attenuation leading to greater potential for VI impacts, and smaller AFs correspond to more attenuation with lower potential VI impacts.

Groundwater to Indoor Air Attenuation Factor
The AF for groundwater to indoor air differs from the soil gas AF because there are two steps. First, partitioning from the water phase to vapor phase must be estimated. Equilibrium partitioning is assumed to obey Henry’s Law. This involves converting the groundwater concentration in micrograms per liter (µg/L) to an equivalent vapor concentration (µg/m3) using the chemical-specific dimensionless Henry’s Law Constant as shown in equation 6, below:

CVapor-GW =CGW × H' × �
1,000L
m3 �
where:

CVapor-GW = Vapor concentration in equilibrium with groundwater in µg/m3 CGW = Groundwater concentration in µg/L
H’ = Chemical-specific Henry’s Law constant (dimensionless) at the specified groundwater temperature.

L = Liters
m3 = Cubic meters
(equation 6)

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Second, the groundwater AF is then calculated as shown in equation 7 below:

AFGW-IA =
CIA
CVapor-GW
where:

AFGW-IA = Groundwater to Indoor Air Attenuation Factor
CIA = Indoor air concentration
CVapor-GW = Vapor concentration in equilibrium with groundwater (equation 7)
Conversion of the groundwater concentration to an equivalent vapor equation assumes there is complete equilibrium between groundwater and soil gas.

Typically, this is not the case due to the capillary fringe described in Section

5.1.1. Therefore, the use of an equilibrium groundwater concentration as a screening tool is usually conservative.

Basis of Attenuation Factors Used in the ESLs
Previous editions of the ESLs have employed AFs derived using versions of the Johnson and Ettinger vapor intrusion model as implemented by USEPA (“Johnson and Ettinger Model” or JEM). Beginning with the 2019 ESLs, an alternative approach is used based on the generic AFs developed from the USEPA Empirical VI Database (USEPA 2012c) and recommended by USEPA (Table 6-1 and Appendix A of USEPA 2015a). The AFs are:
• Subslab Soil Gas and Deep/Exterior AF (AFSG) – 0.03
• Groundwater AF (AFGW) – 0.001
These AFs apply to all buildings, residential and commercial/industrial, current and future.

These empirical AFs are considered both protective and the best science available for the reasons listed herein.
• Empirical VI data are considered superior to VI model predictions because the actual measurements can capture aspects of this complex pathway that may not be adequately considered in models (e.g., preferential pathways) such as the JEM. Most of the JEM inputs are not measured leaving considerable uncertainty. Further, the model assumption of homogeneous subsurface conditions frequently is inconsistent with site conditions. Heterogeneity may be due to natural variation or may result from the construction process (e.g., compaction, preferential pathways around utility conduits). Moreover, the JEM has not been fully validated (McHugh et al. 2017b).

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• USEPA recommended VI AFs are the 95th percentile values that provide a high degree of protectiveness, which is appropriate for screening evaluations. Numerous states have adopted these AFs. The USEPA empirical VI database is the only such database developed by a US regulatory agency and it has been peer-reviewed.
• Overall, Regional Water Board staff have greater confidence in the protectiveness of the USEPA AFs versus our previous model-based AFs.

For site-specific evaluations, our previous model-based approach focused on the review of model inputs rather than verification of model predictions.

Consequently, there are little or no data confirming the protectiveness of model-based AFs to support their continued use.

5.2.2 Soil Gas VI ESLs
The soil gas VI ESL (ESLSG – IA) values are calculated as follows in equation 8:

ESLSG-IA=
CIA
AFSG
where:

CIA Indoor air concentration in µg/m3
AFSG Attenuation factor for all soil gas (subslab and deep/exterior soil gas) (unitless), 0.03
CSG Soil gas (subslab and deep/exterior soil gas) concentration in µg/m3. This is the ESL value.
(equation 8)
External soil gas sample depths generally should be no shallower than five feet bgs to reduce the likelihood of ambient air breakthrough (CalEPA 2015). For other soil gas sampling depth considerations, see the slab capping effect discussion in Section 5.1.1.

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5.2.3 Groundwater VI ESLs
The groundwater VI ESL (ESLGW – IA) values are calculated in equation 9:

ESLGW-IA =
CIA
H' × �
1,000L
m3 � ×AFGW
where:

CGW Groundwater concentration in µg/L. This is the ESL value.

CIA Indoor air concentration (µg/m3)
H’ Chemical-specific Henry’s Law constant (dimensionless) at the specified groundwater temperature
L Liters
m3 Cubic meters
AFGW Attenuation factor for groundwater (unitless)
(equation 9)
Use of the groundwater VI ESLs is not recommended for groundwater samples collected where the depth to groundwater is very shallow (less than 5 feet bgs) due to the potential for unattenuated or enhanced transport of vapors towards a receptor (USEPA 2018a). If groundwater is in contact with the foundation or if there are seeps into the building, sampling indoor is appropriate. For situations where contaminated first encountered groundwater is deep, soil gas analysis can better predict VI potential (see Figure 5-2 and the “slab capping effect” discussion in Section 5.1.1).

5.3 Chemical-Specific Exceptions
Groundwater VI ESLs are not calculated in ESL Workbook Table GW-3 for the volatile petroleum mixtures (gasoline, Stoddard solvent, jet fuel, and diesel).

Instead, it is recommended that vapor data (e.g., soil gas) be collected to evaluate potential VI.

5.4 Site-Specific Evaluations
For sites where soil gas or groundwater VOC concentrations exceed the VI ESL in proximity to a current building, the default assumption is that VI may be occurring unless demonstrated otherwise via site-specific evaluation.

Characterizing the distribution and extent of contaminated groundwater and soil gas and assessing groundwater and vapor plume stabilities are critical steps necessary to determine the need for further evaluation and/or a response action (e.g., mitigation, remediation).

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Options for site-specific evaluations include, but are not limited to, those discussed below, which are not presented in a particular order. Alternative approaches will be considered, provided there is adequate technical justification.

For regulatory review, either a detailed work plan should be submitted, or a thorough scoping meeting conducted before completing the evaluation or submitting a report of findings. This important step reduces the likelihood of unnecessary and costly work and greatly improves the likelihood of regulatory concurrence.

5.4.1 Vapor Conduit Pathway Evaluations: Sewer/Utility
Conduit Air
The US Department of Defense’s Environmental Security Technology Certification Program (ESTCP) recently finalized guidance for assessing this pathway entitled Final Report: Sewers and Utility Tunnels as Preferential Pathways for Volatile Organic Compound Migration into Buildings: Risk Factors and Investigation Protocol (ESTCP guidance; McHugh and Beckley 2018b). The report is accompanied by the Conceptual Model (McHugh and Beckley 2018a) and Investigation Protocol (McHugh and Beckley 2018c).

A key conclusion of the ESTCP guidance is that the complete VI pathway should not be ruled out based on subslab, soil gas or groundwater sample data alone without evaluating the sewer/utility conduit air VI pathway. The Investigation Protocol consists of two steps:
• Desktop Screening – Identify the locations and depths of sewers and utility conduits in the vicinity of release areas or groundwater plumes. Review the information to classify the site as either a greater or lower threat as follows:
o Greater threat – Sites where a sewer or utility conduit directly intersect a groundwater plume or release area.
o Lower threat – Sites where the sewer or utility conduit are in the vadose zone above a groundwater plume or away from release areas. • Field Sampling Investigation – For greater threat sites, sampling of sewer/utility conduit air is recommended for the three highest threat locations identified. These locations are access points (e.g., manholes) located within or downstream of the area where the sewer/conduit intersects contaminated groundwater or NAPL. For lower threat sites, a conventional VI investigation (subsurface media and indoor air) is recommended first. Sewer/utility conduit air sampling can be implemented later if the conventional VI investigation results suggest preferential pathways are a concern. The guidance provides further information such as types of samples (grab vs. time-integrated) and characterization of temporal variability.

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The ESTCP guidance recommends the following sewer to indoor air AFs, developed based on tracer testing, as reasonable upper bound values to evaluate field data: (1) 0.03 for sewer/utility air-to-indoor air; and (2) 0.03 for groundwater-to-sewer/utility conduit air. Note that these two AFs can be combined to yield an overall groundwater via sewer/utility conduit air-to-indoor air AF of 0.001.

Regional Water Board staff recommends the use of the ESTCP Investigation Protocol (McHugh and Beckley 2018c) on an interim basis until formal regulatory agency guidance is developed.

5.4.2 Estimating Site-Specific Attenuation Factors: Vapor Intrusion Models
This section provides background regarding past site-specific model usage in VI evaluations and current expectations for appropriate model usage for estimating site-specific AFs. A checklist is provided in Appendix B indicating the necessary documentation and evaluation required for Regional Water Board staff review.

Background Regarding Site-Specific Model Usage
In the past, fate and transport models such as the USEPA version of the Johnson & Ettinger model (JEM; USEPA 2004a) have been routinely used as part of site specific VI risk assessment for both screening and evaluating risk management measures (e.g., setting cleanup goals). Typically, however, model predictions have not been confirmed via verification monitoring. Findings from the peerreviewed USEPA VI Empirical Database (USEPA 2012c) indicate that attenuation factors generated by the JEM do not predict the 95th percentile of the empirical data. In 2015, USEPA withdrew the 2004 version of the JEM and provided recommendations regarding calibration in Section 6.6 of the OSWER VI Tech Guide (USEPA 2015a). In 2017, USEPA issued a revised version of the JEM (USEPA 2017b). The revised model employs a default subslab AF of 0.003, which corresponds to the median from the USEPA VI Database. The model therefore does not provide the high degree of protection necessary for risk screening evaluations. The model is best used for developing a conceptual understanding of the average VI site scenario but should not be used in a deterministic fashion (e.g., to generate a single AF for a site/building).

Estimating Site-Specific Attenuation Factors
Fate and transport models can be helpful in confirming site-specific subsurface attenuation resulting from the specific geology/hydrogeology beneath a building or in an area where a future building is planned. Such models can be used as a LOE in an MLE evaluation only after a site has been adequately characterized

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and provided the model is adequately constructed, documented, and verified (USEPA 2015a). The most important element to ensure confidence in a model as a LOE is verification of model predictions (e.g., attenuation factor), which will necessitate post-construction verification sampling for future buildings. Therefore, fate and transport models are not considered appropriate during the early screening phase of a project when the site is not adequately characterized and knowledge about the buildings and underlying geology/hydrogeology typically is limited.

Furthermore, models should be used with caution given that current models do not address how buildings change over time due to modifications/renovations, damage, or operational changes (e.g., new HVAC, opening of windows and doors). Moreover, traditional VI models do not consider vapor conduit pathways such as sewer/utility conduit air VI. Therefore, preferential pathways must be ruled out to allow the use of traditional VI models (see Section 5.4.1).

For VI models proposed to predict VI risk at either existing or future buildings, the subslab to indoor air attenuation factor should be fixed at 0.03. The use of 0.03 ensures changes in a building’s vapor attenuation overtime are accounted for when assessing future VI risk. For example, a building’s condition (e.g., age, damage), design (e.g., remodeling), and use (e.g., HVAC operation, opening of windows and doors) will change overtime and affect the soil gas entry and air exchange rates of a building. However, the vapor source to subslab (subsurface) component of the model is less likely to change over time. Therefore, the subsurface component can be based on current site-specific conditions (see Figure 5-4). The Water Board staff review process for VI models is described in the next section.

Figure 5-4 – Conceptual Model for the Development of a Site-Specific Vapor Intrusion Attenuation Factor (AF)

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VI Model Review Process
The Checklist for VI Models should be submitted with all proposed site-specific models/reports and supporting information. An example is included in Appendix B; the most current version is posted on the ESL webpage under Technical Resources. As indicated by the checklist, Water Board staff will review the information regarding the CSM, inputs, outputs and model evaluation. In general, for future buildings where verification with indoor air sampling is not currently possible, a conditional approval may be issued. After adequate post-construction verification sampling and sufficient ongoing performance monitoring have been completed demonstrating that the model is adequately predictive, final approval can be issued.

5.4.3 Petroleum Vapor Intrusion (PVI)
“Petroleum vapor intrusion” (PVI) is defined as the intrusion of vapors from subsurface petroleum hydrocarbons and non-petroleum hydrocarbon fuel additives into overlying or nearby buildings and structures (USEPA 2015b).

At most cleanup sites, chlorinated volatile organic compounds (CVOC) and petroleum hydrocarbons are the main contaminants that pose VI threats.

Consequently, CVOC VI has been referred to as “CVI.” In contrast to most CVOCs, petroleum hydrocarbons biodegrade readily under aerobic (oxygenated) subsurface conditions due to microbial activity in soil. Aerobic biodegradation can limit the upward migration of petroleum vapors in the vadose zone. This is referred to as “bioattenuation.” Such bioattenuation is particularly effective at small petroleum release sites (e.g., gasoline service stations; State Water Board 2012a and 2012b) but occurs to varying extent at all petroleum release sites.

A discussion of the differences between CVI and PVI is presented in Petroleum Hydrocarbons and Chlorinated Solvents Differ in their Potential for Vapor Intrusion (USEPA 2012b). Other helpful guidance for understanding PVI include the Technical Guide for Addressing Petroleum Vapor Intrusion at Leaking Underground Storage Tank Sites (OUST PVI Guide; USEPA 2015b) and Petroleum Vapor Intrusion: Fundamentals of Screening, Investigation, and Management (ITRC 2014). These are listed for the user’s convenience and are not an unrestricted endorsement; consult the overseeing regulatory agency regarding application to a specific site.

PVI Approaches
Petroleum UST sites should follow the LTCP. The LTCP describes physical separation distances between vapor sources and potential receptors, and screening criteria for a subset of petroleum compounds. The Technical Justification for Vapor Intrusion Media-Specific Criteria (State Water Board 2012a) provides the technical rationale.

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At some sites, particularly at complex petroleum release sites such as refineries and bulk terminals, bioattenuation may not be occurring at a sufficient rate to eliminate the PVI threat due to factors such as geochemical conditions, the overall mass of contamination (i.e., size of release), and proximity to the receptor. Figure 5-5 provides examples of two buildings:
• Building A – There is ample vertical separation distance with clean soil between the contamination and building foundation. Bioattenuation is occurring to a sufficient degree to render the PVI pathway incomplete. • Building B – The contamination is close or directly beneath the foundation.

It is uncertain whether biodegradation is occurring to a sufficient degree to render the PVI pathway incomplete. A site-specific biodegradation assessment is warranted. If the PVI pathway is determined to be complete or potentially complete, then an indoor air investigation (indoor air, outdoor air, and subslab soil gas) would be warranted for Building B.

Figure 5-5 – Conceptual Model for the Petroleum Vapor Intrusion Pathway Illustrating When the Pathway is Incomplete and Potentially Complete Source: ITRC 2014.

Site-Specific Biodegradation Assessment
For sites where it is unclear whether biodegradation is occurring to a sufficient degree (as indicated above for Building B), the lines of evidence to evaluate whether there is sufficient bioattenuation of vapors include:

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• Soil Gas Data – Samples from multi-depth soil vapor probes should be analyzed for petroleum, oxygen, carbon dioxide, and methane. The presence of sufficient concentrations of oxygen indicates the potential for biodegradation. The carbon dioxide profile is expected to be the opposite of the oxygen profile. Elevated methane concentrations indicate anaerobic conditions. The methane concentration profile typically follows the same trend as the hydrocarbon concentration profile. For further information see Figure 5-6 below and USEPA (2012b).
• Soil Data – Soil samples should be collected for petroleum analysis between the ground surface and the known or suspected petroleum contamination release area to confirm the presence of a clean soil layer where bioattenuation of petroleum vapors can occur. The presence of residual, less volatile hydrocarbons in contaminated soil increases oxygen demand that can limit bioattenuation of petroleum vapors.

Use of the VI ESLs at Complex Petroleum Sites
The VI ESLs for petroleum chemicals and mixtures can be employed for characterization purposes or as part of a site-specific risk assessment as outlined in the LTCP PVI media-specific criteria. The ESLs for petroleum constituents do not account for bioattenuation and therefore can be overly conservative if bioattenuation is adequately reducing petroleum vapor concentrations as demonstrated via a site-specific biodegradation assessment. After adequate characterization and delineation, it may be appropriate to employ a bioattenuation factor of 1,000 (State Board 2012a and 2012b) for risk screening (i.e., Petroleum Soil Gas VI ESL x 1,000) and evaluation of the need for further actions. This site-specific decision should be made in consultation with the overseeing regulatory agency.

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Figure 5-6 – Typical Vertical Profiles for Concentrations of Petroleum Hydrocarbons (PHCs), Oxygen, Carbon Dioxide and Methane in the Vadose Zone
Source: USEPA 2012b

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6 Methods: Short-Term Action Levels for
TCE in All Media
The ESL Workbook Table entitled “Short Term Action Levels for TCE” presents TCE action levels for groundwater, soil gas, and indoor air, based on the concern for potential adverse effects to developing fetuses when pregnant women inhale low doses of TCE over short exposure periods. The purpose of the action levels and responses is to be protective of sensitive and vulnerable populations, particularly unborn babies. TCE is considered to have the potential to cause fetal cardiac malformations resulting from exposure during the first trimester of pregnancy (USEPA 2011b). These action levels are not screening levels (i.e. VI ESLs should still be used to assess long term risk). Rather, exceedances of the Short-Term Action Levels necessitate certain prescribed response(s) within the corresponding timeframes.

6.1 Background on TCE Noncancer Effects
On September 28, 2011, the USEPA Integrated Risk Information System (IRIS) published new toxicity criteria for TCE (USEPA 2011b). The most significant changes included a substantial reduction in the values for noncancer inhalation toxicity factors and a change in the noncancer toxicity endpoints (adverse effects on specific parts or functions of the human body).

Adverse noncancer health effects documented for TCE include hepatic, renal, neurological, immunological, reproductive and developmental damage. IRIS selected rodent studies showing adverse effects on the kidneys, the immune system and the developing fetus for the 2011 oral reference dose (RfD). The 2011 inhalation reference concentration (RfC) is based on oral studies. The first two endpoints (kidney and immune system) are chronic (long-term) effects, whereas the third (fetal heart malformation) is a developmental effect.

Developmental effects are the result of short-term exposure, in this case a timeframe of three weeks during the first trimester of pregnancy. Developmental toxicity has been linked to inhalation of TCE vapors and ingestion of TCEcontaminated drinking water with more substantial evidence for the latter.

6.2 Short-Term Action Levels, Response Times and
Response Actions for TCE Exposure in Indoor Air
The short-term action levels were originally introduced to the Regional Water Board in a letter from USEPA Region 9 staff (USEPA 2013b). Subsequently, USEPA Region 9 issued a memorandum entitled Response Action Levels and Recommendations to Address Near-Term Inhalation Exposures to TCE in Air from Subsurface Vapor Intrusion (USEPA 2014b). Regional Water Board staff

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included the indoor air action levels in the Draft Interim Framework for Assessment of Vapor Intrusion at TCE-Contaminated Sites in the San Francisco Bay Region (TCE VI Framework; Regional Water Board 2014). In addition, groundwater and soil gas action levels, termed “trigger levels,” were developed as discussed in Section 6.3.

The USEPA short-term action levels, responses, and response time thresholds for TCE in indoor air are presented in ESL Workbook Table entitled “Short Term Action Levels for TCE” under the Indoor Air Action Levels column. USEPA provided for tiered responses based on TCE levels in indoor air as follows:
• TCE in indoor air < accelerated action level – monitor • TCE in indoor air > accelerated action level – mitigate (within weeks) • TCE in indoor air > urgent action level – mitigate (within days) Interim response actions are actions taken by the responsible party or occupant to reduce or eliminate exposure after indoor air sample results exceed the appropriate residential or commercial/industrial TCE accelerated or urgent action level. These actions include encouraging the occupant to immediately take precautions to reduce exposure. Short term response actions (mitigation) include, but are not limited to those listed below:
• Increase ventilation – Increase outdoor air intake, increase building pressurization (buildings with HVAC systems).
• Seal potential conduits
• Treat indoor air – For information on indoor air treatment, see Adsorptionbased Treatment Systems for Removing Chemical Vapors from Indoor Air (USEPA 2017a).
• Temporarily relocate occupants
• Once a response action has been implemented, monitor indoor air as needed to verify success of the response action and determine when additional measures are needed.

Longer term measures include installing a mitigation system until the source can be remediated. For further information on vapor intrusion mitigation systems, see the TCE VI Framework and the Vapor Intrusion Mitigation Advisory (DTSC 2011c).

The short-term action levels, associated response actions, and potential expedited laboratory turnaround times should be incorporated into indoor air sampling work plans and associated response contingency plans.

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6.3 Action Levels and Response Actions for TCE Vapor
Intrusion from Groundwater and Soil Gas
TCE action levels for groundwater and soil gas were developed as a way to expedite indoor air sampling at sites with a higher probability of TCE indoor air concentrations exceeding the short-term response action levels. In the TCE VI Framework, these levels were called “trigger levels.” These trigger levels are calculated using the recommended vapor intrusion attenuation factors (Section 5.2.1) and the short-term action level (noncancer hazard) as the indoor air target concentration.

For sites with deep groundwater (>20 feet bgs) and TCE concentrations only slightly above the TCE groundwater trigger level, expedited soil gas sampling at 15 feet bgs (see Figure 5-2) could be considered before indoor air sampling, on a site-specific basis.

6.4 Potential for Rapid Response Due to TCE Exposure Via Ingestion
The USEPA Region 9 response action levels only address the recent changes regarding the inhalation route for TCE. Because fetal heart malformation risk could increase in pregnant women exposed to TCE from contaminated drinking water, exceedance of the noncancer, ingestion ESL for TCE in drinking water (10 µg/L; ESL Workbook Table GW-1) warrants more immediate action. The investigation and cleanup of TCE-contaminated groundwater for protection of drinking water resources remains a priority for the Regional Water Board, and groundwater cleanup by responsible parties/dischargers should not be delayed.

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7 Methods: Aquatic Habitat Screening
Levels for Groundwater
The ESLs for protection of aquatic habitat presented in ESL Workbook Table GW-2 apply to contaminated groundwater where there is the threat of discharge to surface water. Protecting beneficial uses of aquatic habitat is required by the Basin Plan. Aquatic habitat ESLs consider potential adverse effects to aquatic receptors based on accepted toxicity criteria, and potential impacts to humans based on promulgated bioaccumulation criteria for human ingestion of seafood (e.g., shellfish, fish).

The generic CSM, illustrated in Figure 7-1, assumes contaminated groundwater migrates toward and discharges into a body of surface water, and migration occurs through porous media (e.g., soils/sediments). Potential aquatic receptors include pelagic organisms and biota in the groundwater/surface water transition zone.8 Transition zone biota can include benthic organisms and the microbial community. The transition zone represents a region at or beneath the sediment– water interface (SWI) in a surface-water body where conditions change from a groundwater-dominated system to surface water-dominated system (USEPA 2008b). Transition zones are important ecologically because they store and retain nutrients, transform compounds biologically and chemically, provide refuge to benthic invertebrates, and are the base of the aquatic food web (USEPA 2000d). The generic CSM does not consider dilution or attenuation of groundwater upon discharge to surface water because benthic organisms or other biota in the transition zone may be exposed to the full concentration of contaminants in groundwater prior to mixing with surface water.

8 The transition zone, also known as the hyporheic zone, is an ecological term that generally refers to an ecologic zone where both groundwater and surface water are present in shoreline or streambed sediments along with a specific set of biota. USEPA has chosen to use the broader term “groundwater/surface water transition” zone (USEPA 2000d).

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Figure 7-1 – Bay Margin Groundwater Discharge Conceptual Model This figure depicts contaminant transport via groundwater flow through sediments with potential benthic habitat and then into surface water. The point of compliance (red triangle) is not a fixed location and is located in groundwater outside the influence of surface water and upgradient of transition zone biota (see Section 7.4.1). The biologically active zone is depicted as a purple line.

7.1 Aquatic Receptor Toxicity Criteria
Chronic and acute aquatic receptor toxicity criteria from various sources are compiled in three ESL Workbook Tables:
• IP-5 (California levels) – These are currently the primary sources of the toxicity criteria, specific to California:
o California Toxics Rule (USEPA 2000b);
o A Compilation of Water Quality Goals (State Water Board 2016); and, o Other Criteria - the Basin Plan (Regional Water Board 2017b), Total Maximum Daily Loads, values derived from testing performed under Regional Water Board staff oversight (e.g., petroleum mixture values), or values derived by staff from review of databases or literature (e.g., USEPA ECOTOX).
• IP-6 (USEPA and other levels) – Additional sources include:
o USEPA Ecotox Thresholds (USEPA 1996a);
o USEPA National Recommended Water Quality Criteria (USEPA 2002a);
o U.S. Department of Energy (USDOE) Preliminary Remediation Goals for Ecological Endpoints (USDOE 1997); and,

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o Ontario Ministry of Environment and Energy (MOEE) Rationale for the Development and Application of Generic Soil, Groundwater and Sediment Criteria (MOEE 1996).
• IP-7 (Seafood Ingestion Aquatic Habitat Goals) – These are California Toxics Rule criteria for bioaccumulation and human consumption of aquatic organisms.

7.2 Hierarchy for Aquatic Receptor Toxicity Criteria
There are several sources of toxicity criteria for aquatic receptors such as promulgated criteria, guidance recommendations based on evaluation of results from multiple studies or databases, and individual study results. These criteria include both chronic and acute exposures. Table 7-1 presents a hierarchy of criteria, with the highest being promulgated criteria applicable for chronic exposures. ESL Workbook Table GW-2 uses the hierarchy to determine the Final Freshwater and Saltwater Goals. If a criterion is not available from the highest tier, then a value is selected from the next tier with a criterion value, as described herein.
• For each chemical, a final chronic and acute toxicity level for both freshwater and saltwater receptors is selected. Per the Basin Plan, freshwaters are those in which the salinity is equal to or less than 1 part per thousand for 95 percent of the time. Marine waters (saltwater) are those in which the salinity is equal to or greater than 10 parts per thousand for 95 percent of the time. For waters in which the salinity is between 1 and 10 parts per thousand, the applicable screening levels are the more stringent (i.e., lower) of the freshwater or saltwater levels. • The chronic level is selected using the hierarchy, shown in Table 7-1.

However, if there is a more protective Basin Plan objective value, it will be prioritized over the value selected using the hierarchy. • If no chronic level or Basin Plan objective value is available, 10% of an acute level (termed “adjusted acute goal”) based on the hierarchy is used instead.

The Final Aquatic Habitat Screening Level used as the Tier 1 ESL is the lowest value among the Seafood Ingestion (Bioaccumulation) ESL, Final Freshwater Goal, and Final Saltwater Goal.

Table 7-1 – Hierarchy for Aquatic Receptor Toxicity Criteria Tier Exposure Timeframe Sources of Values
1 Chronic CTR CCC
2 Chronic USEPA CCC

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Tier Exposure Timeframe Sources of Values
3 Chronic
Lowest of:
a) USEPA AWQC;
b) FCV Threshold Value (or the Tier II
value cited in the Ecotox Thresholds if no
AWQC or FCV); or
c) 50 percent USEPA Chronic LOEL1
4 Chronic USDOE Chronic PRG
5 Chronic 50 percent MOEE Chronic AWQC or LOEL
1 Acute CTR CMC
2 Acute USEPA CMC (or Acute LOEL if no CMC)
3 Acute Other aquatic water quality criteria (LC50)
Table 7-1 Note-1: Chemical-specific USDOE Preliminary Remediation Goals (USDOE 1997) are used in place of USEPA chronic LOELs when the LOEL was developed for a general group of compounds rather than a specific chemical.

Table 7-1 Abbreviations:

AWQC – USEPA Ambient Water Quality Criteria
CCC – Criterion Continuous Concentration
CMC – Criterion Maximum Concentration
CTR – California Toxics Rule (USEPA 2000b)
Ecotox – USEPA Ecotox Thresholds (USEPA 1996a)
FCV – Final Chronic Value
LC50 – Lethal Concentration that kills 50% of the population.

LOEL – Low Observed Effects Level
USDOE – US Department of Energy
PRG – USDOE Preliminary Remediation Goal (USDOE 1997)
Ontario MOEE – Ontario Ministry of Environment and Energy

7.3 Chemical-Specific Exceptions

7.3.1 Barium
The USEPA Ecotox freshwater goal for barium (3.9 µg/L; USEPA 1996a) was excluded from ESL Workbook Table IP-6 due to low confidence in the goal.

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7.3.2 Methyl Tertiary Butyl Ether (MTBE)
The freshwater and saltwater surface water goals for MTBE were developed by Regional Water Board staff (Regional Water Board 1998b).

7.3.3 Petroleum Mixtures
• The freshwater and saltwater surface water goals for the petroleum mixtures (e.g., jet fuel, HOPs) are based on aquatic toxicity testing in accordance with Whole Effluent Toxicity (WET) methods or similar methods. Some of the goals are based on testing of laboratory-prepared Water-Accommodated Fractions of fresh (unweathered) mixtures while some are based on testing of contaminated groundwater samples from specific sites.
• When site samples are used for biological effects testing, the tests implicitly address the combined or aggregate effects of all known or unknown potential toxicants in the mixture as well as other factors such as weathering, soil characteristics (e.g., texture, moisture, temperature, pH, carbon content), and microbial community. Consequently, it is difficult to conclude with certainty what caused the toxic response. These values are adopted because the tested mixtures may have caused or contributed to the toxic response in the test species. Therefore, exceedance of these values indicates when it is appropriate to perform site-specific aquatic toxicity testing.
• Information on the specific mixtures, species, and citations are listed below.

Petroleum Gasoline
The freshwater value of 443 µg/L is based on site-specific, chronic toxicity testing of gasoline-contaminated groundwater using the Ceriodaphnia dubia (water flea) (Montgomery Watson 1999). The test design was consistent with recommended test design discussed in Section 7.4.2—toxicity testing was performed in a groundwater sample downgradient from the release area as well as a groundwater sample collected from a background location unimpacted by the petroleum release—no toxicity was found in the background sample. The conclusion is that the toxicity is caused directly or indirectly by the petroleum release.

The saltwater value of 3,700 µg/L is based on chronic toxicity testing of a wateraccommodated fraction (WAF) of fresh (unweathered) gasoline using Strongylocentrotus purpuratus (sea urchin) (Burns and McDonnell Waste Consultants, Inc. 1997). The testing yielded a value of 37,000 µg/L, which was

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adjusted to a final value of 3,700 µg/L using an acute-to-chronic ratio of 10 (Regional Water Board 1998a). The final value was incorporated into subsequent Board Order 99-045 (Regional Water Board 1999).

Petroleum Stoddard Solvent
The Petroleum Stoddard Solvent freshwater and saltwater values are based on the Petroleum Jet Fuel saltwater value as a surrogate.

Petroleum Jet Fuel
The Petroleum Jet Fuel freshwater value is based on the saltwater value (basis described below) as a surrogate. The saltwater value of 640 µg/L is based on chronic toxicity testing of a WAF of fresh (unweathered) Jet A fuel using the Americamysis bahia (mysid shrimp) (Burns and McDonnell Waste Consultants, Inc. 1999; Regional Water Board 1999).

Petroleum Diesel
The Petroleum Diesel freshwater and saltwater values are based on the Petroleum Jet Fuel saltwater value as a surrogate.

Petroleum HOPs
The Petroleum HOPs freshwater value is based on the saltwater value as a surrogate. The saltwater value of 510 µg/L is based on site-specific, chronic toxicity of HOPs-contaminated groundwater using the Americamysis bahia (mysid) (Terraphase Engineering 2018). The test design was consistent with the recommended test design discussed in Section 7.4.2—toxicity testing was performed in groundwater samples downgradient from the release area as well as a groundwater sample collected from a background location unimpacted by the petroleum release—no toxicity was found in the background sample. The conclusion is that the toxicity is caused directly or indirectly by the petroleum release.

7.3.4 Selenium
The freshwater and saltwater surface water goals for selenium in ESL Workbook Table IP-6 are from the California Toxics Rule as promulgated in 40 Code of Federal Regulations Part 131: Water Quality Standards, Establishment of Numerical Criteria for Priority Toxic Pollutants for the State of California (USEPA 2000b). These goals are based on total recoverable, rather than dissolved,

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concentrations. In contrast, the saltwater “Other” criterion column value is a dissolved total value, where total refers to the addition of all selenium species. As indicated in the table footnotes, this is the Total Maximum Daily Load target for North San Francisco Bay based on Board Resolution R2-2015-0048, which was approved by USEPA in 2016.

7.3.5 Tertiary Butyl Alcohol (TBA)
The freshwater chronic aquatic goal is based on staff review of the USEPA ECOTOX database for TBA in 2003. Ten percent of the acute LC50 concentration for Lepomis macrochirus (Bluegill) was selected as the most conservative goal, based on the data available at that time.

7.3.6 1,2,3-Trichloropropane
The freshwater and saltwater chronic aquatic goals are based on staff review of the USEPA ECOTOX database (August 2018). Ten percent of the lowest acute LC50 concentration for Pimephales promelas (fathead minnow) was selected as the freshwater goal. Ten percent of the lowest acute LC50 concentration for Chaetogammarus marinus (amphipod) was selected as the saltwater goal.

7.4 Site-Specific Evaluations
For sites where groundwater concentrations exceed the aquatic habitat ESL in proximity to a surface water body, the default assumption is that a potentially harmful discharge is occurring until demonstrated otherwise via site-specific evaluation. Characterizing the distribution and extent of contaminated groundwater and assessing plume stability are critical steps necessary to determine the need for further evaluation and/or remediation.

Several options for site-specific evaluations are discussed below. Alternative approaches will be considered, provided there is adequate technical justification.

7.4.1 Groundwater Discharge Evaluation
The term “groundwater discharge evaluation” is used to describe the general type of groundwater discharge to surface water investigation necessary where it

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is not possible to determine the extent of contaminated groundwater in proximity to surface water using conventional tools for upland field investigations (e.g., wheeled or tracked drilling rigs). The objectives of the groundwater discharge evaluation are:
• locate and characterize the current or potential discharge area(s); • evaluate the rates or magnitude (flux) of the current or potential discharge; and
• assess the severity/risk/threat to aquatic habitat (e.g., toxicity assessment).

The areas(s) where discharge is occurring or likely to occur must be located so that sampling can be focused to enable the proper evaluation of ecological risks to receptors in the transition zone (USEPA 2008b, TCEQ 2013, NJDEP 2016, MDEQ 2018).

The spatial distribution and rates of groundwater discharge, if occurring, are influenced by the type of associated water body (e.g., stream, wetland, estuary, ocean), the elevation of surface water versus groundwater, and the nature of the sediment substrate (e.g., rocky versus muddy) and hydrogeology. Discharge locations and rates may also be subject to temporal variability due to seasonal and other changes in hydrogeologic conditions.

Due to the dynamic nature of this pathway, a multiple lines of evidence approach is necessary. Typically, the sequence of steps is: (1) evaluate existing information (hydrogeology, hydraulic head, groundwater plume nature and extent); (2) locate potential groundwater discharge areas by visual inspection, temperature and conductivity surveys (or other tracer techniques); (3) determine the nature and quality of sediment porewater9 in the potential discharge areas; and (4) measure seepage/flow and estimate mass discharge. Surface water sampling near the SWI may also be helpful.

The location of the point of compliance (POC) for groundwater discharge evaluations is not by default at the SWI. Rather, the POC should be located to:
(1) represent groundwater outside the influence of surface water; and (2) demonstrate if there are potential adverse effects on transition zone biota (MDEQ 2018).

Tools and methods for groundwater discharge evaluations are described in several documents (Kalbus et al. 2006; Chadwick and Hawkins 2008; USEPA 2008b; Washington DOE 2009; and NJDEP 2016).

9 Sediment porewater, or interstitial water, is the water in the spaces between sediment particles. The origin of porewater can be surface water, groundwater, or a mixture. In a discharge area, porewater is groundwater.

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If the contaminated groundwater discharge is to a storm sewer or other manmade conveyance that discharges to surface water, the CSM is different and the POC location would be the conveyance outfall. In that case, the discharge would be subject to Federal pollution discharge elimination requirements under the Clean Water Act, or waste discharge requirements under the California Water Code.

7.4.2 Site-Specific Aquatic Toxicity Testing
Site-specific aquatic toxicity testing typically is most appropriate when the contaminated groundwater contains:
• Chemicals/mixtures whose toxicity is unknown;
• Several unknown/unidentified chemicals/mixtures;
• Several chemicals known to be toxic to aquatic organisms, but whose individual concentrations do not exceed their respective toxicity criteria (cumulative or synergistic effects);
• Total Dissolved Solids (TDS) concentrations that are significantly different than that of the receiving water; and/or
• A mixture of chemicals/mixtures from multiple releases and the toxicity of the combined mixture cannot be adequately predicted.

Whole Effluent Toxicity (WET) testing can be performed on contaminated groundwater to assess aquatic toxicity and potentially develop site-specific cleanup goals. WET testing methods are a component of the National Pollutant Discharge Elimination System permit program, authorized by the Clean Water Act, that controls water pollution by regulating point source discharges to waters of the United States (SETAC 2004, USEPA 1991b, USEPA 2000c). WET methods are standardized methods for use as water quality regulatory tools (USEPA 2002d, 2002e, and 2002f). In addition, OEHHA (2004b) provides a description of test methods for freshwater and marine toxicity tests for water column, whole sediment, and sediment porewater.

WET testing of uncharacterized complex effluents (mixtures) typically is performed using three relevant species from different taxa for lethal and sublethal endpoints (USEPA 1991b). For uncharacterized complex effluents (mixtures), it is not expected that all test species will show toxic effects. If any single endpoint shows statistically significant toxicity attributable to a pollutant, then that pollutant is deemed toxic. Typically, the most sensitive receptor and endpoint are retained for monitoring of permitted discharges.

Relevant methods and species should be selected considering their known sensitivity to a particular contaminant/mixture. The availability of approved

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methods and species is necessarily limited by factors such as a need for a high degree of standardization, year-round availability, availability of commercial cultures, ease of maintenance and culture in the laboratory, and well-known biology and test requirements (Verslycke et al. 2007). Necessarily, a given test species serves as a surrogate for similar species, even though the test species may not reside at a particular site (USEPA 1994). For example, in the San Francisco Bay region, previous toxicity testing of water samples polluted by petroleum hydrocarbons or their transformation products have found the mysid Americamysis bahia (formerly Mysidopsis bahia) to be a sensitive species (Burns and McDonnell Waste Consultants 1999; Terraphase Engineering 2018). This is consistent with the literature (Barron et al. 1999; Neff et al. 2000) and with the NPDES permit chronic toxicity monitoring programs for four of the five refineries in our region (Phillips 66, Shell, Tesoro, and Valero). Although Americamysis bahia does not reside in the Bay, it is a standard test species (USEPA Method 1007.0) and therefore serves as a surrogate for similar mysids in the Bay (e.g., Neomysis mercedis; Verslycke et al. 2007).

General considerations for WET testing include the potential loss of contaminants during the sample collection/handling and test protocols (e.g., volatilization or biodegradation due to the need to oxygenate) and other potential confounding factors (e.g., un-ionized ammonia, metals, ionic strength).

Specific considerations for WET testing using groundwater matrices/samples include:
• Confirming the test protocol/species will be compatible with the groundwater chemistry;
• Assessing the potential need to adjust the salinity of the groundwater to simulate test conditions for saltwater species;
• Testing a background groundwater sample (unimpacted by the spill in an upgradient or nearby location that has similar hydrogeologic and vegetative characteristics);
• Controlling for potential confounding factors in sample locations proximal to tidally-influenced surface water bodies (e.g., contaminated surface water from other sources or sites); and
• Performing two rounds of testing during different seasons (e.g., wet and dry) to address potential variations in composition and concentrations.

7.4.3 Fate and Transport Modeling
Modeling typically is used as one line of evidence to evaluate the mass flux of contaminated groundwater discharge to surface water and to help focus sampling or evaluate dilution-attenuation factors. If proposed, the modeling approach should employ a generally recognized and scientifically valid method and representative field data should be used to calibrate and verify the model.

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Weighting of the findings (e.g., degree of confidence) will depend on the degree of calibration and whether empirical data are collected to verify estimates and predictions. Ultimately, however, models are not a substitute for sampling to characterize the groundwater discharge to surface water migration pathway.

7.4.4 Additional Considerations for Site-Specific Evaluations Additional considerations are highlighted below:
• Integration of Groundwater Line of Evidence into Ecological Risk Assessments – Traditionally, ecological risk assessments (ERAs) have not considered the ecological importance of the transition zone, instead focusing on biota associated with the SWI or the overlying surface water column (USEPA 2008b). ERAs that do not consider the biota in the transition zone and are focused solely on surface sediments are not an adequate substitute for a groundwater discharge evaluation where contaminated groundwater is potentially impacting aquatic habitat in both the transition zone and the SWI. Groundwater chemistry and toxicity in the discharge zone should be integrated as lines of evidence in ERAs also including bulk sediment chemistry and toxicity and community surveys (USEPA 2008b).
• Background Concentrations of Metals in Groundwater – Background concentrations of barium, boron, copper, lead, mercury, selenium, thallium, and zinc in groundwater, exceeding the aquatic habitat ESLs, have been reported in in the Bay Area. Evaluation of concentrations of naturally occurring background or ambient chemicals is discussed in Chapter 12.

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8 Methods: Terrestrial Habitat Screening
Levels for Soil
The Terrestrial Habitat ESLs in ESL Workbook Table S-2 protect terrestrial receptors (animals and plants) against potential adverse effects from chronic direct exposure to contaminated upland soil. Protecting soil quality ensures a healthy functioning ecosystem capable of sustaining current and future uses of a site by these ecological receptors. The generic conceptual model for exposure to animals and plants assumes the potential maximum depth of exposure to be 10 feet bgs (Sample et al. 2014).

The Terrestrial Habitat ESLs are intended for use only at developed properties and not in agricultural or open lands where special status species10 may be present (e.g., typical habitat of such species). They can be used for screening at such sites but should not be used as the sole basis for screening out these types of sites. The Terrestrial Habitat ESLs also are not applicable to aquatic habitats (e.g., wetlands; ephemeral, intermittent or perennial streams; rivers and mudflats; ponds or lakes; vernal pools; marine intertidal areas). Moreover, Terrestrial Habitat ESLs cannot be used as sediment screening levels; sediment screening levels should be selected on a site-specific basis (see Section 12.5).

8.1 Background and Basis for Screening Levels
Terrestrial Habitat ESLs based on values published in Ontario Ministry of the Environment (MOE) guidance (MOEE 1996) have been used in prior versions of the ESLs from 2001 through 2013. During the 2016 ESL update, the Terrestrial Habitat ESLs were removed. The current Terrestrial Habitat ESLs are based on updated Ontario MOE guidance (MOE 2011). The following provides a summary of the relevant MOE screening levels and how the information has been adapted for use as the Terrestrial Habitat ESLs.

8.1.1 Background on Ontario Ministry of the Environment (MOE) Screening Levels
The screening levels were developed to ensure site soils provide a healthy functioning ecosystem capable of sustaining the current and likely future uses of the site by ecological receptors. These levels were generated through review of

10 Special status species include California species of special concern; state and federally listed rare, threatened, or endangered species; and species that are proposed or recommended for state or federal listing (DTSC 2015).

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scientific literature and other guidance (e.g., Canada and the Netherlands), compilation of data, and a derivation procedure. The literature and guidance review focused on data regarding direct biological effects to growth, reproduction, and mortality to agricultural crops, native plant species and soil-dwelling organisms (e.g., soil invertebrates such as microorganisms, earthworms, insect larvae). The process generated data for three land use categories: 1) agricultural or other; 2) residential, parkland, or institutional; and 3) industrial, commercial, or community. The values for the first two categories are the same while the values for the third category are higher than the first two, recognizing that the level of protection can be less stringent for commercial/industrial uses than for agricultural and residential uses.

The MOE guidance develops two types of soil screening levels (termed “component values”) for two types of terrestrial receptors and exposure pathways, as follows:
• Plants and Soil-Dwelling Organisms: Direct Contact – These component values address direct contact (ingestion, inhalation, dermal contact) for both soil-dwelling organisms and plants. In addition, the component values address aesthetic concerns only for plants. MOEE also created two sets of screening levels based on soil texture: fine- and medium-grained soils and coarse-grained soils. The coarse-grained soil values are about 25% more stringent based on the expectation that the bioavailability of contaminants likely is higher in coarse-grained soils. The fine- and medium-grained soil values are employed in the ESLs.
• Mammals and Birds: Ingestion – These screening levels address both mammals and birds based on food web models with exposure pathways that include a direct or indirect link to soil, including: 1) ingestion of plants; 2) incidental ingestion of soil resulting from feeding on plants and soil invertebrates; and 3) ingestion of prey by carnivores. Due to the large number of potential terrestrial organisms, MOE selected a limited number of terrestrial receptors (typical of agricultural and natural ecosystems in southern Ontario) to serve as surrogates:
o Meadow Vole (Microtus Pennsylvanicus) – surrogate for small herbivorous mammals;
o Short-Tailed Shrew (Blarina brevicauda) – surrogate for species with very high rates of food consumption relative to body weight, which increases exposure and increase their sensitivity;
o Red-Winged Blackbird (Agelarius phoenicus) - surrogate for herbivorous birds;
o American Woodcock (Scolopax minor) - surrogate for omnivorous birds (e.g. robin, killdeer);
o Red Fox (Vulpes vulpes) - surrogate for other predators of small mammals (e.g. coyote, bobcat, lynx, mink);

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o Red-Tailed Hawk (Buteo jamaicensis) – surrogate for carnivorous bird; and
o Sheep (Ovis aries) – surrogate for domestic ruminants (e.g. deer).

It was MOE’s intention to include reptiles and amphibians, but due to lack of information these receptors could not be included. Similarly, there was a lack of information regarding dermal and inhalation exposures to birds and mammals, so these pathways could not be included.

8.1.2 Development of Terrestrial Habitat ESLs
The MOE screening levels previously discussed are included in ESL Workbook Table IP-8 under two categories of terrestrial receptors: (1) plants and soildwelling organisms and (2) mammals and birds. Instead of providing ESLs for residential and commercial land use scenarios, as was done by MOE, the Terrestrial Habitat ESLs consider the degree to which a site is vegetated. For example, the amount of potential terrestrial habitat is much greater at a residence in a rural setting (e.g., open lands) than in a high-density urban residential setting or commercial/industrial setting where much of the surface is covered with buildings or pavement. Therefore, the ESLs were derived for either:
(1) Significantly Vegetated Areas; or (2) Minimally Vegetated Areas. The MOE screening levels derived for residential, parkland, or institutional areas are used for the Significantly Vegetated ESLs while the Minimally Vegetated ESLs are those derived for industrial, commercial, or community areas.

The factors to be considered when determining the vegetation level of a given property can include, but are not limited to the following:
• Urbanization level of the surrounding area
• Percentage of the site covered by vegetation
• Observed animal habitat
A suburban residence with over 50% of the property is covered by vegetation could be considered a substantially vegetated area. On the other hand, almost all high-density urban properties could be considered minimally vegetated areas.

Commercial/ industrial properties likely will be considered minimally vegetated areas.

Ultimately, for a given vegetation level, the lowest value of those for the different receptors is selected for each chemical in Workbook Table S-2. The Tier 1 Soil ESLs assume a significantly vegetated area.

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8.2 Exceptions
The Terrestrial Habitat ESL values for petroleum hydrocarbon mixtures (gasoline, Stoddard solvent, jet fuel, diesel, and motor oil) are based on the results of toxicity testing of weathered mixtures in soil samples collected in the State of Washington (Washington DOE 2016). The toxicity tests were performed using lettuce seed (Lactuca sativa) and earthworms (Eisenia fetida). When site samples are used for biological effects testing, the tests implicitly address the combined or aggregate effects of all known or unknown potential toxicants in the mixture as well as other factors such as weathering, soil characteristics (e.g., texture, moisture, temperature, pH, carbon content), and microbial community.

Consequently, it is difficult to conclude with certainty what caused the toxic response. These values are adopted because the tested mixtures may have caused or contributed to the toxic response in the test species.

Santa Cruz City CouncilJune 24, 2025

Santa Cruz City Council
June 24, 2025