Agenda packet — Wheatland City Council, February 11, 2025

REGULAR CITY COUNCIL MEETINGAgenda
February 11, 2025 at 6:00 PM
Wheatland Community Center: 101 C Street, Wheatland, CA 95692 City Council meetings are held in-person and are no longer available via ZOOM.

In compliance with the Americans with Disabilities Act, if you are a disabled person and you need a disability-related modification or accommodation to participate in this meeting, please contact City Hall at (530) 633-2761 or (530) 633-9102 (fax). Requests must be made as early as possible and at least one full business day before the start of the meeting.

1. OPENING MATTERS

1.1 Call to Order and Roll Call

1.2 Pledge of Allegiance to the Flag

2. PUBLIC COMMENT
At this time, the public is permitted to address the City Council on non-agendized items.

COMMENTS SHOULD NOT EXCEED THREE (3) MINUTES. In accordance with State Law, however, no action or discussion may take place on any item not appearing on the posted agenda. The Council may respond to statements made or questions asked or may request Staff to report back at a future meeting concerning the matter. Any member of the public may contact the City Clerk’s Office related to the proper procedure to place an item on a future City Council agenda. The exceptions under which the Council MAY discuss and/or act on items not appearing on the agenda are contained in Government Code §54954.2(b) (1) (2) (3)

3. CONSENT CALENDAR

3.1 DRAFT Minutes - Regular City Council Meeting - 01/28/25

3.2 Consideration and Adoption of Resolution Approving Appointments to the Feather River Air Quality Management District Board of Directors

3.3 Consideration and Adoption of Resolution Canceling the Regular City Council Meeting of March 11, 2025

3.4 Proclamation - Honoring the 150th Anniversary of Grace Episcopal Church

4. PUBLIC HEARING

5. PRESENTATIONS

5.1 Presentation from Sacramento Area Council of Governments

6. REGULAR CALENDAR
1 6.1 Consideration and Adoption of Resolution Ratifying Agreement with BK Custom Concrete for Emergency Corporation Yard Repairs

7. REPORTS

8. CLOSED SESSION

9. ADJOURN
Any writings or documents provided to a majority of the Wheatland City Council after distribution of the agenda packet are available for public inspection on the City’s website, www.wheatland.ca.gov This institution is an equal opportunity provider, and employer. 2 Regular City Council Meeting Minutes
January 28, 2025, at 6:00 PM
Wheatland Community Center: 101 C Street, Wheatland, CA 95692 City Council meetings are held in-person and are no longer available via ZOOM.

1. OPENING MATTERS

1.1 Call to Order and Roll Call
Mayor Angela Teter called the meeting to order at 6:00 p.m.

1.2 Pledge of Allegiance to the Flag
Mayor Angela Teter led the Pledge of Allegiance

2. PUBLIC COMMENT
At this time, the public is permitted to address the City Council on non-agendized items.

3. CONSENT CALENDAR
Motion made by Council Member Coe, Seconded by Council Member Abe.

Voting Yea: Mayor Teter, Vice Mayor McIntosh, Council Member Coe, Council Member Abe

3.1 DRAFT Minutes - Regular City Council Meeting 01-14-25

3.2 Consideration and Adoption of Resolution Designating Representatives for Labor Negotiations for the City of Wheatland

4. PUBLIC HEARING
3 Section 3, Item # 3.1

5. PRESENTATIONS

6. REGULAR CALENDAR

6.1 Council Consideration and Adoption of Resolution Updating Conflict of Interest Code Provisions Concerning Architectural and Engineering Services Administration and Procurement for Federally and State-Funded Transportation Projects Vice Mayor L. McIntosh commented on the contract administrator.

Motion made by Council Member Abe, Seconded by Council Member Coe.

Voting Yea: Mayor Teter, Vice Mayor McIntosh, Council Member Coe, Council Member Abe

6.2 Consideration and Adoption of Resolution Authorizing the Execution of a Professional Services Agreement with Dokken Engineering for Engineering and Environmental Services for the Wheatland Road Complete Streets Project Council Member B. Abe questioned why only one Request For Proposal (RFP) was received.

Council Member Abe also questioned if street lights for the project meet specifications by federal law and could the City post a second RFP.

Vice Mayor L. McIntosh questioned if Dokken Engineering has previously done this type of work and if there is a way to include construction of a sidewalk from the Bear Ridge apartments on Spenceville into the City. Vice Mayor McIntosh also questioned if a second RFP were posted could the scope of work include the sidewalk in front of the Bear Ridge Apartments and questioned the timeline on grant funds.

Mayor A. Teter questioned the chances of the project going over budget.

Motion made by Council Member Coe, Seconded by Council Member Abe.

Voting Yea: Mayor Teter, Vice Mayor McIntosh, Council Member Coe, Council Member Abe

6.3 South County Infrastructure Project Update
Terri Daly from the Yuba Water Agency presented council and audience members with a powerpoint presentation for the South County Infrastructure Project Update. The presentation included information on challenges, a map of the project area, solutions and benefits, project schedule, current status, financing strategies and next steps.

Fire Chief Art Paquette questioned if Beale AFB connects to the project, how much capacity would be used at the Olivehurst Public Utilities District (OPUD) facility.

Council Member B. Abe questioned where Beale AFB would connect into the OPUD system.

Council Member B. Abe also questioned a connection at South Beale Road.

Vice Mayor L. McIntosh questioned why the City hasn't entered into a Joint Powers Authority (JPA).

Resident Chris Walsh questioned funding from Beale AFb, a potential waste line and imminent domain.

This was an information item only.
4 Section 3, Item # 3.1

7. REPORTS
Police Chief Brian Wittmer reported on the School District license plate readers, the school district safety grant, and the OTS step grant.

City Engineer Dane Schilling reported on completion of the sinkhole repair in the Public Works corporation yard and stated it is safe now.

City Manager Bill Zenoni reported on a Caltrans meeting to discuss possible options at Dairy Road and Highway 65, flower boxes in C Street park, restroom repairs and solar lights for the parking lot.

Mayor A. Teter reported that Wheatland will hold a SACOG meeting in September.

Mayor A. Teter announced adjournment to the Closed Session portion of the meeting at 7:01 p.m.

8. CLOSED SESSION
Mayor A. Teter reconvened the regular council meeting at 8:00 p.m. with no reportable action taken during closed session.

8.1 Conference with Labor Negotiator (California Government Code Section 54957.6.) City Designated Representative: Bill Zenoni, City Manager
Employee Organizations: Wheatland General Employees Association, Wheatland Police Officers Association, and Wheatland Sergeants Associations

9. ADJOURN
There being no other further business, Mayor A. Teter adjourned the meeting at 8:00 p.m.

Any writings or documents provided to a majority of the Wheatland City Council after distribution of the agenda packet are available for public inspection on the City’s website, www.wheatland.ca.gov This institution is an equal opportunity provider, and employer. 5 Section 3, Item # 3.1
City Council Meeting Staff Report
Meeting Date: February 11, 2025
Subject: Consideration and Adoption of Resolution Approving Appointments to the Feather River Air Quality Management District Board of Directors Prepared By: Bill Zenoni, City Manager
Recommendation: Staff recommends that the Wheatland City Council consider adoption of a resolution approving appointments to the Feather River Air Quality Management District Board of Directors for the 2025 calendar year.

Discussion: The Feather River Air Quality Management District is a bi-county District that was formed in 1991 to administer local, state and federal air quality management programs for Yuba and Sutter counties. The mission of the Feather River Air Quality Management District is to promote and improve the air quality of Yuba and Sutter counties.

The Feather River Air Quality Management District is governed by a nine-member Board of Directors.

One member is appointed from each city and two members are appointed from each county. Annually, each city approves the appointment of the directors of the other participating cities (Marysville, Yuba City and Live Oak).

The Wheatland City Council, on January 14, 2025, approved the appointment of Brian Abe and John Abe as the representative Feather River Air Quality Management District board member and alternate respectively for the City of Wheatland for the 2025 calendar year. The District is now requesting that the Wheatland City Council approve the appointments made by the cities of Marysville, Yuba City and Live Oak. Those three municipalities will in turn consider approval of the board appointments for the other three cities, including Wheatland.

The Feather River Air Quality Management District Board of Directors appointments presented for the Wheatland City Council approval are:

City of Marysville
Councilmember Stuart Gilchrist (Director)
Councilmember Bruce Buttacavoli (Alternate)
City of Yuba City
Councilmember Mike Pasquale (Director)
Councilmember Wade Kirchner (Alternate)
City of Live Oak
Councilmember Aaron Pamma (Director)
Councilmember Jeremy Chapdelaine (Alternate)
Fiscal Impact: None
Attachments:

1. Letter from Feather River Air Quality Management District

2. Resolution
6 Section 3, Item # 3.2
7 Section 3, Item # 3.2
RESOLUTION NO. __-25

A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF WHEATLAND APPROVING

APPOINTMENTS TO THE FEATHER RIVER AIR QUALITY MANAGEMENT DISTRICT

BOARD OF DIRECTORS
WHEREAS, the Feather River Air Quality Management District is a bi-county District that was formed in 1991 to administer local, state and federal air quality management programs for Yuba and Sutter counties; and
WHEREAS, the Feather River Air Quality Management District is governed by a ninemember Board of Directors; and WHEREAS, the Wheatland City Council, on January 14, 2025, approved the appointment of Brian Abe and John Abe as the representative Feather River Air Quality Management District board member and alternate respectively for the City of Wheatland for the 2025 calendar year; and
WHEREAS, the Feather River Air Quality Management District has requested that the Wheatland City Council approve the board member appointments made by the cities of Marysville, Yuba City and Live Oak.

NOW, THEREFORE, BE IT RESOLVED by the City Council of the City of Wheatland approves the following appointments to the Feather River Air Quality Management District Board of Directors for the 2025 calendar year:

AYES:

ABSENT:

ABSTAIN:

ATTEST:
________________________
Angela Teter, Mayor
______________________________
Lisa J. Thomason, City Clerk
9 Section 3, Item # 3.2
City Council Meeting Staff Report
Meeting Date: February 11, 2025
Subject: Consideration and Adoption of Resolution Canceling the Regular City Council Meeting of March 11, 2025
Prepared By: Bill Zenoni, City Manager
Recommendation: Staff recommends that the Wheatland City Council consider adoption of a resolution canceling the regular City Council meeting of March 11, 2025.

Discussion: The City Council conducts regular meetings on the second and fourth Tuesday of each month. Due to a lack of urgent business for the City Council to conduct on March 11, 2025, it is recommended that the regular City Council meeting of March 11, 2025 be canceled.

If approved, a notice of the meeting cancellation will be posted.

Fiscal Impact: None
Attachment:

1. Resolution
10 Section 3, Item # 3.3
RESOLUTION NO. __-25

A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF WHEATLAND CANCELING THE REGULAR CITY COUNCIL MEETING OF MARCH 11, 2025
WHEREAS, the regular meetings of the City Council are set for the second and fourth Tuesdays of every month; and
WHEREAS, the City Council has the authority to cancel meetings when necessary; and WHEREAS, it has been determined that there is no urgent business for the City Council to conduct on March 11, 2025.

NOW, THEREFORE, BE IT RESOLVED by the City Council of the City of Wheatland that the March 11, 2025 City Council meeting is canceled.

PASSED AND ADOPTED by the City Council of the City of Wheatland on the 11th day of February 2025 by the following vote:

AYES:

ABSENT:

ABSTAIN:

ATTEST:
________________________
Angela Teter, Mayor
______________________________
Lisa J. Thomason, City Clerk
11 Section 3, Item # 3.3

PROCLAMATION OF THE CITY OF WHEATLAND, CALIFORNIA
HONORING THE 150TH ANNIVERSARY OF THE GRACE EPSICOPAL CHURCH WHEREAS, the Grace Episcopal Church in Wheatland was built in 1874; and WHEREAS, a congregation of 18 worshiped for the first time on Nov. 15, 1874. Now 150 years old, Grace Episcopal Church continues to play a vital role in this historic city; and WHEREAS, Grace Episcopal Church has a thriving congregation and encourages the community to attend Sunday services: and
WHEREAS, adding to the history of the Grace Episcopal Church, Pioneer Memorial Hall in Wheatland is also a part of the church. Pioneer Hall was built in 1914. The Wheatland Historical Society, Veterans of Foreign Wars, and other organizations meet in Pioneer Memorial Hall; and
WHEREAS, the Grace Episcopal Church welcomes people of all faiths and for them to know they are accepted with much love; and
WHEREAS, the Grace Episcopal Church encourages community members to join them for a 10 a.m. Sunday service. For months with five Sundays, the fifth Sunday service may be held either in Grace Episcopal Church, or at an Episcopal or Lutheran church in Marysville, Yuba City or Colusa. This information, and more, is available at the church’s website:
www.gracewheatland.org
NOW THEREFORE BE IT PROCLAIMED, the City Council of the City of Wheatland hereby joins in honoring and celebrating the 150th Anniversary of the Grace Episcopal Church, 610 Third Street, Wheatland, and the positive impact the church has in our community for being strongly engaged with community service and various traditions. ______________________
Angela Teter, Mayor
12 Section 3, Item # 3.4
City Council Meeting Staff Report
Meeting Date: February 11, 2025
Subject: Presentation from Sacramento Area Council of Governments Prepared By: Bill Zenoni, City Manager
Recommendation: Staff recommends that the Wheatland City Council receive a presentation from the Sacramento Area Council of Governments.

Discussion: The Sacramento Area Council of Governments (SACOG) is an association of local governments in the six county Sacramento region that provides transportation, planning, and funding for the region and serves as a forum for the study and resolution of regional issues. In addition to preparing the region’s long-range transportation plan, SACOG approves the distribution of affordable housing in the region and assists in planning for transit, bicycle networks, clean air and airport land uses.

SACOG is currently updating its long-range transportation plan, known as the 2025 Blueprint, which aims to integrate multimodal transportation systems and regional land use development. This plan will connect housing to jobs, education, goods, services, and recreational opportunities while protecting the region's natural landscapes. James Corless, SACOG’s Executive Director, will make a presentation to the Wheatland City Council to provide information on the 2025 SACOG Blueprint and discuss findings from a recent region-wide transportation and land use analysis. Mr. Corless will also summarize the various programs available to assist public agencies in implementing the SACOG Blueprint locally.

SACOG staff have been advised that Council members may have questions regarding SACOG’s support of transportation needs within the City of Wheatland.

Fiscal Impact: None
Attachment: None
13 Section 5, Item # 5.1
City Council Meeting Staff Report
Meeting Date: February 11, 2025
Subject: Consideration and Adoption of Resolution Ratifying Agreement with BK Custom Concrete for Emergency Corporation Yard Repairs
Prepared By: Dane H. Schilling – City Engineer
Recommendation:

Adoption of Resolution 08-25 ratifying an agreement with BK Custom Concrete for emergency sinkhole repairs at the City of Wheatland Corporation Yard.

Discussion:

On April 11, 2024, City of Wheatland Public Works staff discovered a large and deep void in the ground at the City Corporation Yard at 208 Fourth Street in Wheatland. The subterranean void surfaced adjacent to a steel framed building that houses equipment, machinery, parts and supplies for the City’s public works functions.

On April 12, 2024, investigations involving the City Manager, Public Works Director, City Engineer and a professional geologist began. The City’s insurer, the California Intergovernmental Risk Authority (CIRA), was notified by the City Manager of the potential loss. On May 6, 2024, a property loss claim was filed with CIRA with an estimate cost of $264,000 for services and construction costs to assess and repair the damage.

On September 24, 2024, the City Council adopted Resolution No. 43-24 which waived the formal bidding processes in accordance with California Public Contract Code Section 20168 and authorized the City Manager to execute any necessary agreements to repair damages.

The City Engineer and consulting geologist Blackburn Consulting worked with Public Works staff to determine probable causes, assess the extent of the damage incurred and develop a repair plan. A repair plan was developed and formulated into a bid package for informal bidding.

In October 2024 an advertisement for bids was posted on CIPlist.com, sent to local bid rooms and contractor associations, and several contractors specializing in foundation repairs and concrete work were directly solicited by the City Engineer. Contractors indicating interest in the work included:

Pinnacle Home Services of Sacramento, Webb Construction of Wheatland, Groundworks-Commercial of California, and BK Custom Concrete of Yuba City.

Bid packages were sent to interested contractors. Three contractors performed site investigations in consideration of submitting bids and two declined to bid citing the higher risk associated with the project. One contractor was only willing to go further if the City performed more testing associated with a proprietary method of polyurethane injection which was determined not to be a proven or costeffective option considering the size of the voids. 14 Section 6, Item # 6.1
By November 11th only one contractor, BK Custom Concrete had submitted a bid for the project. The items on the bid form were broken into two phases. Phase 1 included stabilizing the building and higher risk areas such as the ground under the building by filling largest of voids with minimal ground disturbing activities.

Phase 2 work included remediation of lower risk shallow voids, surface level work and site restoration based on negotiated prices and time-and-materials work. All work except the filling of shallow voids directly under the building slab have been completed. The following is a summary of work items and costs:

Summary – BK Custom Concrete Contract
Phase 1
Shore Building & Stablilize Main Voids
Fill Augured Exploration Holes
$29,226.00
$ 2,325.00
Phase 2
Fill Shallow Voids & Site Restoration
Fill Shallow Voids Under Building Slab*
$34,780.00
$ 8,000.00
TOTAL CONTRACT $74,331.00
*estimated cost for time and materials work yet to be
performed
Fiscal Impact:

The current estimated total cost of the construction contract with BK Custom Concrete is $74,331.00 with one item of work remaining to be completed. The City’s insurance deductible of $25,000 will be paid from the Water, Sewer, General and other associated funds (Project No.190045). The remainder of the costs in the amount of $49,331.00 will be submitted under the City’s insurance claim to CIRA.

Attachments
Attachment 1 – Resolution 08-25
Attachment 2 – Contract with BK Custom Concrete
15 Section 6, Item # 6.1

Page 1 of 1 ends

RESOLUTION NO. 08-25

RESOLUTION OF THE CITY COUNCIL OF THE CITY OF WHEATLAND

RATIFYING AN AGREEMENT WITH BK CUSTOM CONCRETE OF YUBA CITY FOR

CONSTRUCTION OF EMERGENCY CORPORATION YARD REPAIRS
WHEREAS, on April 11, 2024, City of Wheatland Public Works staff discovered a large and deep void in the ground at the City Corporation Yard at 208 Fourth Street in Wheatland that presented a threat to the safety of City staff and the public; and WHEREAS, on September 24, 2024, the City Council adopted Resolution No. 43-24 which waived the formal bidding processes in accordance with California Public Contract Code Section 20168 and authorized the City Manager to execute any necessary agreements to repair damages; and
WHEREAS, in October 2024, an advertisement for bids was posted on a public bidding website, sent to local contractor associations and sent to licensed contractors in the vicinity of Wheatland; and
WHEREAS, by November 11, 2024, one bid had been received from BK Custom Concrete that was later examined by the City Engineer and recommended to the City Manager for execution.

NOW, THEREFORE IT IS HEREBY RESOLVED, ORDERED AND FOUND by the City Council of the City of Wheatland, State of California, to ratify an agreement made by the City Manager with BK Custom Concrete of Yuba City in the amount of $82,331.00 for the remediation, repair and restoration of a sinkhole and associated damage sustained at the City of Wheatland Corporation Yard located at 208 Fourth Street.

PASSED AND ADOPTED by the City Council of the City of Wheatland, State of California this 11th day of February 2025, by the following vote:

AYES:

NOES:

ABSTAIN:

ABSENT:

ATTEST:
______________________________
Angela Teter, Mayor Lisa Thomason, City Clerk
16 Section 6, Item # 6.1
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43 Section 6, Item # 6.1
City of Wheatland
111 C Street Wheatland, California 95692
TELEPHONE (530) 633-2761
FAX (530) 633-9102
October 2024
Invitation to Bid
Wheatland Corporation Yard Sinkhole Repair Project
The City of Wheatland, California is informally seeking bids for this emergency repair project to repair damage due to an abandon well under a City maintenance building located at 208 Fourth Street in Wheatland.

Proposals will be received electronically by the City Engineer at [email protected] until a sufficient response is received. In General, the Project consists of demolition, shoring, excavating loose soils, CLSM backfill, injection grouting, minor grading and asphalt paving. The anticipates a Notice to Proceed on November 13, 2024, and work shall be performed within 30 calendar days.

This is an informal bidding process. There will be no pre-bid conference for this project. Each bid must be submitted on the prescribed forms. The successful bidder will be required to furnish a payment bond and faithful performance bond each in the full amount of the contract price, and insurance with certificates and endorsements of insurance, as provided in the Contract Documents.

The successful bidder must possess the following classification or type of contractor's license issued by the California Contractors State License Board: Class A OR Class B. To be qualified to bid on this Project, bidders must be registered and qualified to perform public work with the Department of Industrial Relations pursuant section 1725.5 of the Labor Code. All subcontractors listed in a qualified bidder’s bid as performing any portion of the work also must be registered and qualified with the Department of Industrial Relations.

Bidders are directed to the requirements and conditions of employment to be observed and prevailing wage rates to be paid to all workers employed under the Contract in accordance with Labor Code sections 1770 and following.

The City reserves the right to reject all bids. Any bid not conforming to the intent and purpose of the Contract Documents may be rejected.

Dane Schilling, PE
City Engineer
44 Section 6, Item # 6.1
City of Wheatland - Corp Yard Sinkhole Repair
ITEM
1 2
3 SHORE EXISTING BUILDING FOUNDATIONS
4 LOCATE EXISTING ABANDONED WELL
5 EXTRACT LOOSE MATERIAL IN VOIDS
6 SLURRY BACKFILL WELL & VOIDS
The southeasterly corner of the building foundation is unsupported/hanging (approximately 10- to 12-linear feet, see photos in report). Work includes placing jacks, shoring and/or cribbing to safely support edge of building during construction. Solid concrete and steel shoring materials may be abandoned in-place at the discretion of the City Engineer.

Mark the location of the well on the ground using remote field measurements taken from the opening in the largest void to the visible portion of the brick well structure. Measurements can be electronic or direct physical measurements using tools to reach into the void. Once located, core hole(s) in slab or asphalt pavement over the well, auger through subgrade soils (if any). The City will document the conditions with photos and ascertain the depth.

Work involves removing any loose soils from voids that are accessible from the ground surface without entering the voids. It is assumed that a crew and equipment will perform soil extraction over the period of one 8-hr work day.

Additional work days may be added at the discretion of the City. The City's expected work sequence and equipment includes:

Method: Reach into the void from the surface level (no excavations over the void) by inserting a vacuum hose/pipe with a floor attachment from a vactor truck down the invert of the void, insert air lance with circular diffuser to dislodge loose soils from the walls of the void, send the tube back down retrieve loose soil; repeat as necessary.

Equipment:
-Vacuum truck with positive displacement of 18" Hg @ 3,500-cfm, 8" diameter pick-up hose and articulated boom with minimum 20-ft reach; 8" diameter pipe extensions and 8" flat floor attachment; and misc. rigging. - Compressor and air lance operating with 100- to 249-psi range with 360-degree dispersion nozzle, and ridged extensions as needed.

Work involves placing controlled low strength material (CLSM) in voids from the ground level. Deliver CLSM by tremie methods to fill well and voids from the bottom up. CLSM should have a minimum 28-day unconfined compressive strength between 200 and 500 pounds per square inch (psi).

DESCRIPTION OF WORK ITEMS

DESCRIPTION

MOBILIZATION AND DEMOBILIZATION
5% max. allowance based on the sum of all other costs. Also includes site security, house keeping and final clean-up.

TRENCH SHORING AND BRACING
Contractor to provide as-needed to meet OSHA requirements.

Page 1 of 2 ends

45 Section 6, Item # 6.1
City of Wheatland - Corp Yard Sinkhole Repair
7a INJECTION GROUT CONC. BLDG. SLAB
or 7b REMOVE AND REPLACE CONC. BLDG. SLAB
8 REMOVE EXISTING PAVEMENT
9 PREPARE SUBGRADE & REGRADE TO DRAIN
10 ASPHALT PAVEMENT (4" THICK, 1/2" TYPE A)
After the voids have been filled and CLSM has achieved 14-day strength, saw cut and remove a 20'x70' section of asphalt paving beginning at the back of the public sidewalk/driveway and continuing alongside the building.

Work includes adjusting grades to slope pavement away from building to form a slight V-gutter in the re-paved area.

Work includes minor adjustments to existing utility boxes and covers (3 estimated). The paved area is 20' x 70' extending from the existing back of sidewalk/driveway and continues southeasterly alongside the buildings.

Work involves injection grouting below the floor slab and along edge of CLSM by drilling injection locations throughout the eastern 600-sf of the existing floor slabs and along the eastern edge of the void . The grout should have a minimum 28-day unconfined compressive strength of at least 100 psi but not greater than 500 psi.

Contractor to determine the number, location, and layout of the injection points. Grout should be injected into each port until grout return is observed from adjacent injection holes, slab cracks, or ground surface, and/or the slab/foundation lifts more than acceptable. Multiple stages of injection grouting may be required to adequately fill the void below the floor slab and foundations. See attachment for injection grouting material specifications.

Work involves saw cutting and removal of 600-sf of existing reinforced concrete slab (excluding perimeter foundations); backfilling any voids under the slab; doweling reinforcing bar into remaining concrete; and pouring an in-kind reinforced concrete replacement slab.

Page 2 of 2 ends

46 Section 6, Item # 6.1
City of Wheatland - Corp Yard Sinkhole Repair

ITEM CONSTRUCTION QTY UNITS UNIT COST TOTAL
1 MOBILIZATION AND DEMOBILIZATION 5 % -
2 TRENCH SHORING AND BRACING 1 LS
3 SHORE EXISTING BUILDING FOUNDATIONS 1 LS
4 LOCATE EXISTING ABANDONED WELL 1 LS
5 EXTRACT LOOSE MATERIAL IN VOIDS 1 DAY
6 SLURRY BACKFILL WELL & VOIDS 42 CY
7a INJECTION GROUT CONC. BLDG. SLAB 15 CY
or 7b REMOVE AND REPLACE CONC. BLDG. SLAB 600 SF
8 REMOVE EXISTING PAVEMENT 1,400 SF
9 PREPARE SUBGRADE & REGRADE TO DRAIN 1,400 SF
10 ASPHALT PAVEMENT (4" THICK, 1/2" TYPE A) 34 TON
TOTAL $ _____________________
Written Amount:___________________________________________________________________ Submission Date:__________________ Bidder Signature:______________________________ Company Name: _________________________________________________ Address: _______________________________________________________ Phone No.: _____________________________________________________ Email: _________________________________________________________ CSLB License No(s).: ______________________________________________

BID FORM
47 Section 6, Item # 6.1
Auburn Office:
11521 Blocker Drive, Ste 110
Auburn, CA 95603 West Sacramento (916) 375-8706
(530) 887-1494 Fresno (559) 438-8411
File No. 4782.X
October 23, 2024
City of Wheatland
Mr. Bill Zenoni
City Manager
111 C street
Wheatland, CA 95692
Subject: GEOTECHNICAL CONSULTATION – REVISION 1
208 4th Street
Wheatland, California
Dear Mr. Zenoni,
Blackburn Consulting (Blackburn) appreciates the opportunity to provide geotechnical consultation services for the void that has formed below the City of Wheatland (City) Water Department Operations Building at 208 4th Street in Wheatland, California. Blackburn prepared a letter dated April 17, 2024, presenting preliminary conclusions, and recommendations. Below is a summary of site observations, review of available information, conclusions, recommendations for filling the void, and limitations. The recommendations in this updated letter supersede recommendations presented previously.

SITE DESCRIPTION AND PURPOSE
The site is occupied by the City’s Water Department and Public Works operations building and shop/warehouse. Site improvements include:
- Single-story concrete masonry unit (CMU) operations building supported on shallow concrete spread footings.
- A Single-story steel framed shop/warehouse supported on shallow concrete spread footings. - Asphalt pavements.
- Water pumps and pipelines.
- Water tanks (elevated and at grade), and
- Emergency backup generators.

Photo 1 shows the conditions near the shop/warehouse.
48 Section 6, Item # 6.1
GEOTECHNICAL CONSULTATION MEMORANDUM – REVISION 1
208 4th Street, Wheatland, CA
October 23, 2024

2 Photo 1: 208 4th Street
Looking North toward 4th Street.

We understand City employees found a hole in the pavement near the southeast corner of the shop/warehouse building (coned area in Photo 1) on Thursday April 11, 2024, while moving a fuel storage cabinet (yellow cabinet on east side of shop/warehouse in Photo 1). The City contacted Coastland Engineering who requested Blackburn visit the site to observe the conditions, provide a professional opinion regarding likely cause(s) of the void, and preliminary recommendations to mitigate/ fill the void.

We prepared this memo to summarize our observations, conclusions, and preliminary recommendations.

SUMMARY OF SITE OBSERVATIONS
Blackburn’s engineer Haze Rodgers visited the site on April 12, 2024. Photos 2 through 4 show some of the void conditions observed during the site visit. Haze observed:
• A hole approximately 4 feet in diameter in the asphalt pavement near the southeast corner of the shop/warehouse building.
• Approximately 1 foot of the pavement laterally around the hole was depressed and undermined. • The southeastern corner, eastern perimeter footing, and floor slab of the shop/warehouse building was undermined (Photo 3 and 4).
• The void extended to the north (Photo 3), and to the south and southwest (Photo 4). • A brick structure was observed at the northern end of the void (Photo 3). • The base of the void is covered with loose soil, Aggregate Base, and debris (AC pieces, leaves, etc.). • The depth and horizontal extents of the void are unknown but estimated to extend to a depth of at least 20 feet below the ground surface at the northern end. • Significant distress was not observed inside the shop/warehouse building at the southeastern corner; however, some cracks were observed in the floor slab near the northeast corner. 49 Section 6, Item # 6.1
GEOTECHNICAL CONSULTATION MEMORANDUM – REVISION 1
208 4th Street, Wheatland, CA
October 23, 2024

3 Photo 2: 208 4th Street
Undermined asphalt pavement at east edge of void. Bottom of AC is observed at top of photo.

Photo 3: 208 4th Street
Looking North down void toward 4th Street. Eastern perimeter footing is visible at top left corner of photo, and Brick structure is observed at end of void.
50 Section 6, Item # 6.1
GEOTECHNICAL CONSULTATION MEMORANDUM – REVISION 1
208 4th Street, Wheatland, CA
October 23, 2024

4 Photo 4: 208 4th Street
Looking Southwest below southeast corner of shop/warehouse building. Corner and eastern perimeter footing are visible.

Blackburn’s engineer Luke Morrell visited the site on July 10, 2024, with Subtronic corporation to survey the area around the existing buildings for underground utilities. Subtronic marked the locations of the detected underground utilities with paint in the field. Subtronic’s report is included as Attachment A and includes pictures of the underground utilities detected and marked by Subtronic.

REVIEW OF AVAILABLE INFORMATION
Blackburn reviewed:
- Publicly available geological, topographic, and historic aerial photos, - Contacted the Yolo County Environmental Health Department, and - Reviewed the City of Wheatland Letter titled: Sink hole at Wheatland Corporation Yard, 208, 4th Street, Wheatland, California, dated 22 April 2024.

The publicly available geologic and topographic maps do not identify former mine works, quarries, or other past uses or geologic formation that would be conducive to the formation of the void. 51 Section 6, Item # 6.1
GEOTECHNICAL CONSULTATION MEMORANDUM – REVISION 1
208 4th Street, Wheatland, CA
October 23, 2024

5 The historic aerial photos show the site has been occupied by the City of Wheatland Water Company/Department since before 1900. Excerpts of the 1899 Sanborn map (Figure 1 and Exhibit C of Attachment B) show a well below the northern portion of the existing shop building approximately above the brick observed at the base of the void (Photo 3). Yuba County Environmental Health does not have any records or information about the presence or abandonment of the well shown on the 1899 Sanborn map. The City concluded (Attachment B):
- The brick observed in the void could be the casing of the former well. - The former well would be at least 30 feet deep, and
- Have a diameter of approximately 4 to 6 feet.

Coastland Engineering attempted to map the extents of the void and location of the brick structure.

Exhibits A and B of the City’s letter (Attachment B) show the results of Coastland’s mapping.

CONCLUSIONS
Based on our observations, review of available historical information, we conclude the void is likely caused by backward erosion piping of soil into the improperly abandoned well. The soil is likely being transported by surface water (from storm water, irrigation, etc.) that seeps into the soil and flows to the historic well. On-site stormwater could also enter the ground at the cold joint between the pavement and perimeter building foundations.

RECOMMENDATIONS
Based on our observations, available information, and experience with similar projects we recommend:
- Remove the loose soil and debris from the void to expose firm native soil. - Backfill the void and well in at least two stages:
o Stage 1: Place controlled Low Strength material (CLSM) in the well and void by tremie methods to fill the void and well from the bottom up. CLSM should have a minimum 28- day unconfined compressive strength between 200 and 500 pounds per square inch (psi). o Stage 2: Injection grout below the floor slab and along edge of CLSM. The grout should have a minimum 28-day unconfined compressive strength of at least 100 psi but not greater than 500 psi.

The contractor might need to drill through the floor slab within the existing building to extend the tremie pipe to bottom of the well and completely fill the well.

Injection grouting uses a fluid like (low viscosity) cementitious or polymer grout placed under pressure using a probe/nozzle to fill voids in confined areas, small voids/fissures, and can be used to re-level floor slabs and foundations of light structures. The contractor should determine the number, location, and layout of the injection points; however, we recommend injections locations be placed throughout the eastern half of the existing floor slabs and along the eastern edge of the void. Grout should be injected into each port until grout return is observed from adjacent injection holes, slab cracks, or ground surface, and/or the slab/foundation lifts more than acceptable. Multiple stages of injection grouting may be required to adequately fill the void below the floor slab and foundations. Attachment C includes a draft specification for injection grouting.
52 Section 6, Item # 6.1
GEOTECHNICAL CONSULTATION MEMORANDUM – REVISION 1
208 4th Street, Wheatland, CA
October 23, 2024

6 SERVICES DURING CONSTRUCTION
Blackburn should provide the following services during Repair:
• Review design specifications and plans prepared by others. • Review contractor submittals, RFI’s, and workplans.
• Full-time observation and documentation during placement of CLSM and injection grouting.

Specifically, observe and record the following:
o Batch tickets/Mix Proportions
o Injection/ placement locations
o Material volumes (take)
o Injection pressures
o Grout specific gravity
• Collect CLSM and grout samples for compression testing. • Perform compression tests on CLSM and grout samples.

LIMITATIONS
Do not use the information in this memorandum for design or construction on this site. We prepared this memo based on our site observations, information provided by others, and published data. Do not use or rely on the information for different locations or repairs/improvements without Blackburn’s written consent.

Our scope does not include subsurface exploration or laboratory testing. Blackburn has not reviewed or performed a geotechnical investigation, laboratory testing, or engineering calculations for the project. Our conclusions and recommendations are based on the results of our review, a brief site visit, and information provided. A geotechnical exploration, laboratory testing, and engineering analyses must be performed to properly design and construct the repair.

Thank you for contacting us to help. Please call if you have questions or require additional information.

Sincerely,

BLACKBURN CONSULTING
Reviewed by:

Haze m. Rodgers, P.E., G.E. Richard D. Rodgers, P.E., G.E.

Geotechnical Director Senior Consultant
Attachments: A – Subtronic Utility Survey report
B – City of Wheatland Letter
C – Injection Grout Sample Specification
53 Section 6, Item # 6.1

GEOTECHNICAL CONSULTATION

MEMORANDUM
208 4th Street, Wheatland, CA
Attachment A:

Subtronic Utility Survey report
54 Section 6, Item # 6.1
Personal Pre-Work Check
[x]Locator has Correct/Special Equipment
[x]Meeting client
[]Correctly defined area of work
-Map BelowJob Safety Analysis
Client:Blackburn Consulting
Job / Estimate #:39441
Date / Time:7/10 @ 930
Client Representative:Luke
Completed by:ryan
Lead Person:Ryan
Type of Job
[x]Locating
[x]Surveying
[]CCTV
55 Section 6, Item # 6.1
[]Potholing
[]Leak Detection
[]Geophysical Survey
Description of Work
(2) 20'x20' areas
Upon arrival Luke has increased size of
scope to one 30'x75' area and one 15'x30'
area. He has ok'd any extra time this
increase in scope will cause
Roster: (By signing, employees acknowledge they reviewed all hazards and controls identified)
1 2
3 4
5 6
Emergency Action Plan
Emergency phone No.: 911
56 Section 6, Item # 6.1
First Aid Station:in truck
Location of Phone:on person
Equipment Shut Down Procedure:na
General Hazard Assessment
Potential Hazard(s) & Methods to control / eliminate hazards identified [x]Hand Injury: Wear correct gloves, use proper tools, identify pinch points [x]Fall / Trip: Manholes are out of harm’s way / protect open holes, uneven surfaces. [x]Eye Injury: Wear safety glasses, upgrade to face shield when needed []Lifting Hazards: Know your limits, use buddy system, use lifting / carrying devices []Falling Objects: Rope oF areas if needed, wear hard hat []Head Injury: Wear hard hat, beware of surroundings
[]Excessive Noise: Wear appropriate hearing protection, (ear plugs / muFs or both) [x]Foot Injury: Wear steal toed boots, identify uneven surfaces, take measures to eliminate hazards
[]Slippery Surfaces: Wet areas, asphalt, grass, concrete, rocks, gravel, warn others [x]Heat Stress: Drink plenty of water, utilize work-rest cycle, limit exposure to sun, use sunscreen, use buddy system
[]Cold Stress: Ensure adequate clothing, construct wind / rain barriers, wear proper rain gear
[]Hot / Cold Surfaces: Wear proper gloves, apply proper barriers, avoid line of fire []Respiratory Protection: Determine IDLH atmosphere, monitor air quality, determine proper respiratory protection. Ventilate areas
57 Section 6, Item # 6.1
[]Confined Space: Identify ALL hazards of space per confined space entry form and follow.
[]Tra7ic Road Control: Follow permit instructions, be aware of vehicles, correct road signs.
[x]Pedestrian Control: Be Aware of people at all times, [x]Electrical Hazard: Use GFCI, ensure proper grounding []Stored Energy (LO/TO): Verify isolation of energy sources with authorized personnel before beginning work, ensure aFected personnel are notified [x]Hazwopper: Training and valid certifications
COVID-19 Hazard Assessment
[]Hands: Wear correct protective gloves. Latex. Use disinfected wipes and sanitizer. Wash frequently at least 20 seconds with soap and water. Avoid touching common areas with bare hands
[]Face: Avoid touching face, nose, mouth, or head area until proper cleaning is done []Social Distancing: Maintain at least 6 feet distance, do not group, do not carpool. []Eye Protection: Wear safety glasses always, disinfect before and after each use. []Disinfecting Equipment: Use disinfected wipes, disinfecting spray on equipment after use.
[]Cleaning Vehicle: Use disinfecting wipes on steering wheel, inside vehicle, handles inside and out, etc.
[]Cough/Sneeze: Do not cough or sneeze into hands, cough or sneeze into cloth or tissue, arm of elbow
[]Phones: Do Not share, disinfect regularly.
[]Respiratory Protection: Wear cotton masks, Bandana’s, etc, N-95 masks when needed for inside work.
[x]Symptoms: Any employees with symptoms (Fever, Cough, Shortness of breath) are directed to stay home if recognized before arriving, or will be sent home if symptoms come up after their arrival.
58 Section 6, Item # 6.1
Additional Hazards

TASK HAZARD CONTROL METHOD
CONFINED SPACE ENTRY PERMIT (If Required):

LOCATING - JOB SITE LOG & PROGRESS REPORT
Job / Estimate #:

Tim
e
Notes
930- Locate utilities
59 Section 6, Item # 6.1
60 Section 6, Item # 6.1
61 Section 6, Item # 6.1
62 Section 6, Item # 6.1
63 Section 6, Item # 6.1
64 Section 6, Item # 6.1
65 Section 6, Item # 6.1
66 Section 6, Item # 6.1
67 Section 6, Item # 6.1
68 Section 6, Item # 6.1
69 Section 6, Item # 6.1
70 Section 6, Item # 6.1
71 Section 6, Item # 6.1
72 Section 6, Item # 6.1
73 Section 6, Item # 6.1
74 Section 6, Item # 6.1
75 Section 6, Item # 6.1
76 Section 6, Item # 6.1
77 Section 6, Item # 6.1
78 Section 6, Item # 6.1
79 Section 6, Item # 6.1
80 Section 6, Item # 6.1
81 Section 6, Item # 6.1
82 Section 6, Item # 6.1
83 Section 6, Item # 6.1
84 Section 6, Item # 6.1
Utilities Not Located/Not Locatable
Utility Notes
[]Electrical
[]Communications
[x]Water
Parts of water are PVC, and cannot be located
electronically
[x]Gas
Poor trace on private side gas at meter,no trace on
gas at generator separate from com and electric
runs. Either gas is non conductive and signal is
bleeding onto other utilities, or it is joint trenched
with the Electric and Communication lines to the
generator
[]Storm Drain
[x]Sanitary Sewer Unable to locate cleanout to confirm sewer location [x]Other
Site is heavily congested with plant, piping, electric
communication, etc., requested print to help sort
out which utility is which was told that that is not
available. Clamp to all nearby piping and conduits
and marked pathways. It is unable to be determined
the number or type of utility in each pathway, or if all pathways have been accounted for as they all share
common bonds.
85 Section 6, Item # 6.1
Post-Locate Checklist
Active Locating
[]Measure Valves to Top of Nut if Required
[]Measure Clean-Out Inverts
[]Pictures of Work Completed in Notes
Passive Scanning
[x]Power
[x]Radio
[x]GPR
[x]Twinbox

SITE WORK COMPLETION
Job / Estimate #:
[]All Equipment Accounted For
Customer Feedback Survey

Strongly
Disagree
Disagree Agree
Strongly
Agree
I do
not
know
All safety measures were
in place prior to start of
Job.
[] [] [] [] []
The technician was
knowledgeable in the
service provided.
[] [] [] [] []
86 Section 6, Item # 6.1
The technician was
professional and
courteous
[] [] [] [] []
The equipment provided
was clean and in
excellent working order
[] [] [] [] []
The job was completed
within
scope/estimate/contract.
[] [] [] [] []
I received final reports in
a timely matter.
[] [] [] [] []
I feel the oFice personnel
was helpful and
answered all my
questions.
[] [] [] [] []
Would you recommend
Subtonic for your next
project?
[] [] [] [] []
Additional Comments:
-On-Site Signature of Client Representative87
Section 6, Item # 6.1

GEOTECHNICAL CONSULTATION

MEMORANDUM
208 4th Street, Wheatland, CA
Attachment B:

City of Wheatland Letter
88 Section 6, Item # 6.1
City of Wheatland
111 C Street Wheatland, California 95692
TELEPHONE (530) 633-2761
FAX (530) 633-9102
April 22, 2024
Erike Young - Deputy General Manager
CIRA
2330 E. Bidwell Street
Folsom, CA 95630
Subject: Sink Hole at Wheatland Corporation Yard; 208 4th Street, Wheatland, CA Dear Mr. Young:

On the afternoon of April 11, 2024, the City’s Public Works staff was working at the City’s Corporation Yard (“Site”) and discovered a hole in the pavement just outside of a shop building located at the northwest corner of the Site (see Photo 1) that revealed a large underground void.

Photo 1: Aerial View of Wheatland’s Corp Yard
SHOP
BLDG.

WATER OPS
BLDG.

STORAGE
TANK

ELEVATED
TANK

INITIAL
HOLE
89 Section 6, Item # 6.1
Erike Young
April 22, 2024

Page 2 of 8 ends

Structures at the Site include a water operations control building, shop building, parking area, a 660,000- gallon water storage tank, a 70,000-gallon elevated tank, a diesel generator, water pumps, piping and a municipal well (Well #3) at the northeast corner of the site. The City also stores vehicles and equipment at the Site. The steel-framed shop building was constructed circa 1950’s with a concrete slab-on-grade, concrete foundation, and concrete spread footings at each of its structural columns. The water operations building, consisting of masonry walls and metal roof, was constructed circa 2002 as part of the City’s USDA water system modernization project.

After discovering the hole and void, Staff carefully removed a 3-ft x 5-ft area asphalt paving around the original hole which revealed a very large and deep void with tunnels extending in two directions:
beneath the shop building foundation and slab; and extending under the asphalt road into the yard.

Photo 2 shows the location of the hole in the asphalt. The white line on the pavement in Photo 2 shows the approximate limit of the void beyond the building.

Photo 2: Location of Hole in Pavement (facing northwest towards 4th Street) Initial estimates indicate that building foundation has been undercut by the void leaving at much as 25-ft of the east side of the building foundation and slab unsupported. Photo 3 shows the exposed void and the unsupported spread footing.
90 Section 6, Item # 6.1
Erike Young
April 22, 2024

Page 3 of 8 ends

Photo 3: Exposed Foundation and Spread Footing, Tunnel to the Southeast of the Hole On the following day City Manager Bill Zenoni, City Engineer Dane Schilling with Coastland Engineering and consulting engineering geologist Haze Rodgers with Blackburn Consulting visited the site to examine and document the damage.

In the following week, Public Works Staff further explored the void using underground utility cameras which revealed the smaller void is a tunnel that extends to the southeast of the surface hole and is 1- to 3-ft in diameter and approximately 20-ft in length (see Exhibits A and B). The larger void extends along the easterly edge of the shop building and angles to the northwest for approximately 25-feet to a depth of approximately 25-ft and ranges from 3- to 6-ft in diameter. Approximately 15-feet from the opening in the asphalt, the void turns into a tunnel with approximately 6’-8’ of material bridging over the void (see Photo 4).

BOTTOM OF BUILDING FOOTING

BOTTOM OF SPREAD FOOTING
91 Section 6, Item # 6.1
Erike Young
April 22, 2024

Page 4 of 8 ends

Photo 4: Tunnel Facing Northwest of the Hole
At the farthest/deepest part of the large void a brick structure is barely visible and appears to be arranged in a convex configuration such as the outside edge of a cylindrical structure (see Photo 5).

SOIL BRIDGING AS

DEPTH INCREASES

ELECTRICAL SERVICE

TO SHOP BUILDING

ELECTRICAL

GROUNDING RODS
92 Section 6, Item # 6.1
Erike Young
April 22, 2024

Page 5 of 8 ends

Photo 5: Brick Exposed at End of Tunnel
A 1899 Sandborn Map (Figure 1 and Exhibit C) indicates that a well was present near the turn of the century along with two storage tanks. Apparently, the well was abandoned in-place but the means and extent of the abandonment cannot be ascertained at this time. It is known from recent work in the area that ground water that would be available for municipal use is available at depths of 30- to 40-feet below ground surface. Therefore, it is estimated that the abandoned well is at least 30-feet in depth. 93 Section 6, Item # 6.1
Erike Young
April 22, 2024

Page 6 of 8 ends

Figure 1: Portion of 1899 Sandborn Map at Corp Yard site with well indicated by arrow The Shop Building appears to have been built over of a portion of the historic well. The brick that is visible from looking into the void is expected to be the outside of the well casing. If the brick structure is indeed the old well, it would likely be approximately 4-6 feet in diameter and it is expected that it would have been at least 30-feet in depth to reach groundwater and supply the 40-horse power pump shown on the map.

On April 19, 2024, the City and Coastland attempted to map the limits and depth of the void based on what can be safely seen from the opening in the pavement. The resulting map and profile views of the approximate limits of damage are included as Exhibits A and B.

Preliminary Assessment and Causation
Preliminary information indicates that surface storm water from the improvements at the Corp Yard site, including roof downspouts and pavement draining to the easterly side of the Shop Building, have found a pathway to the abandoned historic well which was able to receive and drain the water. In the process of the stormwater draining to the well, soil was eroded and transported toward the well – a condition in geotechnical engineering known as “piping”. Soils are “piped” when saturated soils under hydrostatic pressure flow to areas of lower pressure. Although the initial flows begin as water moving through the soil matrix, the situation can progress to include the erosion of soils in the areas of highest hydrostatic pressure and lower soil strength which eventually leads to acute soil erosion in the form of “pipes” that lead to an outlet for the hydrostatic pressure and soil. The size of the pipes can increase as 94 Section 6, Item # 6.1
Erike Young
April 22, 2024

Page 7 of 8 ends

water flows more freely and more soil is transported away. Also, recent storms in the Sacramento region have been notably more intense in terms of inches of rainfall per hour which would likely cause sustained periods of runoff and, therefore, caused more and possibly accelerated erosion at the Site due to piping.

In addition, based on the volume of lost or displaced soil material that is large enough to create the size and depth of the void that is visible, it is likely that soil has been displaced or transported away via bottom the well. At this point in time, the apparent cause of the soil loss and resulting void is due to the occurrence heavy rains resulting in erosion and transportation of soil material. The pavement where the original hole developed is in a low-lying spot relative to the surrounding pavement and buildings, so any runoff from the paved area collects near the low spot. The Water Operations and Shop Buildings collect runoff in downspouts that outlet on to the pavement along the easterly sides of both buildings and runoff is directed toward the sink hole and initial hole in the asphalt.

Action Items
The following are suggested next steps and considerations in response to the situation:

1. Protect the area from any sources of storm water by covering and diverting water away from the immediate area prior to future rain events. This may be accomplished with plastic sheeting, supporting plywood, sandbags and diversion pipes from the building downspouts to 4th Street.

2. Suspend use of the main entry driveway, portions of the yard area, the Shop Building and possibly the use of the public sidewalk on 4th Street as needed and establish a safety zone to protect City staff and the public from hazards associated with the void.

3. As more information becomes available, re-evaluate and adjust the safety-zone and cordon off any unsafe areas outside and inside the buildings.

4. De energize and lock-out/tag-out the electrical service to the Shop Building.

5. Prevent any loads or vibrations in the immediate area including vehicles, equipment, motors and the large generator adjacent to the void.

6. Ascertain the depth and measures originally used to abandon the well (if any) by exploring the well with a video camera.

7. Search County records for any additional information on the well.

8. To the extent safely possible, remove existing racks, equipment, tools, hardware, flammables and supplies in and around the shop building. This should be accomplished without additional loads to the ground within the hazard areas.
95 Section 6, Item # 6.1
Erike Young
April 22, 2024

Page 8 of 8 ends

9. Establish a scope of work, plans and specifications for:
a. Securing the Shop Building from further damage by temporarily supporting/shoring the exposed foundations;
b. Abandoning the well to modern standards;
c. Removing loose soils and properly filling the void to provide adequate support for the buildings, large water mains, vehicles and activities at the yard; d. Restore damaged/altered/removed facilities, buildings, pavement, concrete slabs, electrical, etc.;
e. Ensure that drainage pathways from the buildings and yard are properly and safely draining to existing storm drain systems.

The City anticipates that the expenses for securing the site, further investigations and engineering work, and remediation and repair of damages will exceed the City’s $25,000 deductible. Therefore, this letter serves as the City’s notice of potential claim to CIRA for this incident. Please let me know if you have any further informational needs or questions on this matter.

Sincerely,
Bil Zenoni
City Manager
Attachments:

Exhibit A – Plan of Corp Yard Sink Hole Limits
Exhibit B – Profile of Corp Yard Sink Hole Limits
Exhibit C – Overlay of 1899 Sandborn Map on Corp Yard Site Letter from Blackburn Consulting to Dane Schilling, April 17, 2024 Copy: Jennifer Buckman – City Attorney
Dale Klever – Public Works Director
Dane H. Schilling – City Engineer
96 Section 6, Item # 6.1
COASTLAND | DCCM
11641 Blocker Dr, Ste 170
Auburn, CA 95603
530.888.9929 | coastlandcivil.com

CITY OF WHEATLAND

CORP YARD SINKHOLE LIMITS
APRIL 22, 2024 REVISION 1 EXHIBIT A
97 Section 6, Item # 6.1
COASTLAND | DCCM
11641 Blocker Dr, Ste 170
Auburn, CA 95603
530.888.9929 | coastlandcivil.com

CITY OF WHEATLAND CORP YARD
SINKHOLE PROFLE VIEW - APPROX. LIMITS
APRIL 22, 2024 REVISION 1 EXHIBIT B 98
Section 6, Item # 6.1
COASTLAND | DCCM
11641 Blocker Dr, Ste 170
Auburn, CA 95603
530.888.9929 | coastlandcivil.com

CITY OF WHEATLAND CORP YARD

SANDBORN MAP OVERLAY
APRIL 22, 2024 REVISION 1 EXHIBIT C
99 Section 6, Item # 6.1
Auburn Office:
11521 Blocker Drive, Ste 110
Auburn, CA 95603 West Sacramento (916) 375-8706
(530) 887-1494 Fresno (559) 438-8411
File No. 2871.X 007
April 17, 2024
Coastland Engineering
Mr. Dane Schilling
11641 Blocker Dr. Suite 170
Auburn, CA 95603
Subject: GEOTECHNICAL CONSULTATION
208 4th Street
Wheatland, California
Dear Mr. Schilling,
Blackburn Consulting (Blackburn) appreciates the opportunity to provide geotechnical consultation services for the void that has formed below the City of Wheatland Water Department Operations Building at 208 4th Street in Wheatland, California. Below is a summary of site observations, conclusions, preliminary recommendations, and limitations.

SITE DESCRIPTION AND PURPOSE
The site is occupied by the City of Wheatland Water Department and Public Works operations building and shop/warehouse. Site improvements include:
- Single-story concrete masonry unit (CMU) operations building supported on shallow concrete spread footings.
- A Single-story steel framed shop/warehouse supported on shallow concrete spread footings. - Asphalt pavements.
- Water pumps and pipelines.
- Water tanks (elevated and at grade), and
- Emergency backup generators.

Photo 1 shows the conditions near the shop/warehouse.
100
Section 6, Item # 6.1

GEOTECHNICAL CONSULTATION MEMORANDUM
208 4th Street, Wheatland, CA
April 17, 2024

2 Photo 1: 208 4th Street
Looking North toward 4th Street.

We understand City of Wheatland employees found a hole in the pavement near the southeast corner of the shop/warehouse building (coned area in Photo 1) on Thursday April 11, 2024, while moving a fuel storage cabinet (yellow cabinet on east side of shop/warehouse in Photo 1). The City contacted Coastland Engineering who requested Blackburn visit the site to observe the conditions, provide a professional opinion regarding likely cause(s) of the void, and preliminary recommendations to mitigate/ fill the void.

We prepared this memo to summarize our observations, conclusions, and preliminary recommendations.

SUMMARY OF SITE OBSERVATIONS
Blackburn’s engineer Haze Rodgers visited the site on April 12, 2024. Photos 2 through 4 show some of the void conditions observed during the site visit. Haze observed:
• A hole approximately 4 feet in diameter in the asphalt pavement near the southeast corner of the shop/warehouse building.
• Approximately 1 foot of the pavement around the hole was depressed and undermined. • The southeastern corner, eastern perimeter footing, and floor slab of the shop/warehouse building was undermined (Photo 2).
• The void extended to the north (Photo 3), and to the south and southwest (Photo 4). • A brick structure was observed at the northern end of the void (Photo 3). • The base of the void is covered with loose soil, Aggregate Base and debris (AC pieces, leaves, etc.). • The depth and horizontal extents of the void are unknown but estimated to extend to a depth of at least 20 feet below the ground surface at the northern end. • Significant distress was not observed inside the shop/warehouse building at the southeastern corner; however, some cracks were observed in the floor slab near the northeast corner. 101
Section 6, Item # 6.1

GEOTECHNICAL CONSULTATION MEMORANDUM
208 4th Street, Wheatland, CA
April 17, 2024

3 Photo 2: 208 4th Street
Undermined asphalt pavement at east edge of void. Bottom of AC is observed at top of photo.

Photo 3: 208 4th Street
Looking North down void toward 4th Street. Eastern perimeter footing is visible at top left corner of photo, and Brick structure is observed at end of void.
102
Section 6, Item # 6.1

GEOTECHNICAL CONSULTATION MEMORANDUM
208 4th Street, Wheatland, CA
April 17, 2024

4 Photo 4: 208 4th Street
Looking Southwest below southeast corner of shop/warehouse building. Corner and eastern perimeter footing are visible.

Mr. Dane Schilling (Coastland) was present and had access to historical Sanborn maps. According to Dane, one of the Sanborn maps shows water tanks and a well near the location of current shop/warehouse building. The depth and size of the well were not reported on the map.

CONCLUSIONS
Based on our observations, available historical information, we conclude the void is likely caused by backward erosion piping of soil into an improperly abandoned well. The soil is likely being transported by surface water (from storm water, irrigation, etc.) that seeps into the soil and flows to the historic well. On-site stormwater could also enter the ground at the cold joint between the pavement and perimeter building foundations.

Preliminary Recommendations
Based on our observations, available information, and experience with similar projects we provide the following preliminary repair recommendations:
- A “No-access”/exclusion zone (for both the interior and exterior) within 20 feet of the eastern edge of the shop/warehouse building should be established. No equipment or material storage should be allowed within the exclusion zone. Equipment, vehicles and materials stored within the exclusion area should be relocated outside the exclusion zone. - Determine and map the depth and horizontal extents of the void, and location of the suspected well. - Expose the suspected well and observe and measure the depth and size of the well (or other feature if different).
103
Section 6, Item # 6.1

GEOTECHNICAL CONSULTATION MEMORANDUM
208 4th Street, Wheatland, CA
April 17, 2024
5 - Remove the loose soil and debris from the base of the mapped void and well/feature to expose firm native soil.
- Backfill the void and well with CLSM. CLSM should a minimum 28-day unconfined compressive strength between 200 and 500 pounds per square inch (psi).

Due to the depth and extent of undermining below the building foundations we anticipate shoring and underpinning will be required. The type and design of the underpinning and shoring depend on the subsurface conditions, contractor means and methods, and actual extent and depth of the void. To provide the geotechnical information necessary to provide recommendations for a contractor to determine and design the shoring and underpinning we recommend a geotechnical subsurface investigation be performed. The subsurface investigation should include:
• Review of available subsurface information
• Drilling, sampling, and logging two borings near the void. The borings should be advanced at least 10 feet below the bottom of the void.
• Geotechnical laboratory testing to provide engineering properties of the in-situ native soil, and recommendations for use in the design of shoring and underpinning. • Engineering evaluations and recommendations for:
o Void excavation and backfill, including clean out, appropriate materials, and criteria. o Lateral earth pressures (active, at rest, and passive) for design of shoring. o Allowable bearing pressures for underpinning elements. o Temporary slopes.
o Floor slab repair.
o Additional services during construction.
• A summary letter presenting the results of the geotechnical investigation and evaluations.

GEOTECHNICAL CONSULTATION MEMORANDUM
208 4th Street, Wheatland, CA
April 17, 2024
6 Thank you for contacting us to help. Please call if you have questions or require additional information.

Sincerely,

BLACKBURN CONSULTING
Reviewed by:

Haze Rodgers, P.E., G.E. Rob Pickard, P.G., C.E.G
Geotechnical Director Senior Engineering Geologist
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Section 6, Item # 6.1

GEOTECHNICAL CONSULTATION

MEMORANDUM
208 4th Street, Wheatland, CA
Attachment C:

Injection Grout Sample Specification
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Section 6, Item # 6.1
------------------------------------------------------------------------------------------------------------------ SECTION 02800

INJECTION GROUTING
------------------------------------------------------------------------------------------------------------------ PART 1: GENERAL

1.01 SUMMARY
A. Furnish all labor, material, equipment, transportation, and services necessary for the completion of all injection grouting work indicated in the project documents.

B. The contractor shall review the available project and site information.

1.02 INJECTION GROUT
A. Definition: "Injection Grout," as referred to herein, is a relatively non-viscous grout that is injected into the ground or a void. The grout can consist of cementitious and chemical (polymer) materials that undergo a reaction that results in solidification of the injected for the purpose of filling voids in the soil and below surface improvements, and reestablishing support if the surface improvements.

B. The materials used shall be so proportioned and mixed as to produce a grout that contains no solids, may be pumped without difficulty, will penetrate and fill the voids in the soil mass, and will result in a stable solid material of the required strength and stability.

C. The Contractor shall submit, for approval by the Geotechnical Engineer, detailed sketches of the intended injection techniques and patterns and shall submit, for approval by the Geotechnical Engineer, necessary data to prove that the grout mixture contemplated will meet in all respects the requirements as to properties and qualities required by these Specifications.

D. Authorization of use under license must be filed with Engineer for the use of any chemical system that is covered with a current patent. 107
Section 6, Item # 6.1

1.03 DETERMINATION OF ACTUAL WORK LIMITS
A. Voids beneath the existing floor slab and designated areas surrounding CSLM (to be placed under this contract prior to injection grouting) shall be grouted. Depth of grouting shall be determined based on field conditions. For estimation purposes, an average depth of 10 feet should be assumed and unit prices shall be provided on a costper-unit volume basis.

B. Grouting beneath existing foundations shall be thorough and complete and shall extend to the boundary between the soil and the bottom of existing foundation.

PART 2: PRODUCTS

2.01 MATERIALS
A. Grout shall be composed of a uniform mixture of polymer, cement, or other proprietary material. The grout mix proportions are to be determined by the contractor and submitted for review and approval to the City.

B. Grout mix can include cement, polymers, or other chemical binders.

C. Water used shall be compatible with the binder/cement used.

D. Considering the chemistry of the grout and the conditions known at the site, the chemical system shall produce a stable grout. The chemical system used shall be permanent and shall have a proven record of stability.

E. Chemicals mixed into primary solutions, before final batching, may be held only in accordance with the manufacturer's recommendations and must not be injected or held beyond the specified time, exposed to critical temperatures, exposed to sunlight, or other limiting factors imposed by the manufacturer. Any solutions deemed unsuitable to be used for the injection shall be immediately disposed of to the satisfaction of the Engineer.

F. The unconfined compressive strength of grout shall be at least 100 pounds per square inch (psi) at 28 days but not greater than 500 psi.

2.02 EQUIPMENT
A. The grout plant shall be capable of supplying, mixing, stirring, and pumping the grout. Mixing and pumping equipment used in the preparation and handling the grout shall be maintained in first-class operating condition at all times. 108
Section 6, Item # 6.1
B. Mixing equipment shall be capable of thoroughly mixing the primary constituents to the proper solution strength and shall be capable of thoroughly mixing these constituents in the final batching. In the event that temperatures fall to a critical temperature for the required solution strengths, provision shall be made to heat solutions, in accordance with the material manufacturer's recommendations, or grouting shall be suspended until proper temperatures and re-mix occur. Under no conditions will compressed air "bubble mixing" be allowed.

C. Drilling Equipment: Injection points shall be installed by either rotary drilling methods or by percussion. If rotary drilling methods are used, the injection pipes shall be installed in the hole in such a way as to form a tight seal around the pipe and confine the grout to the required injection depth. The injection ports shall be of sufficient clear inside diameter and strength to accommodate the maximum grout pressure and flow rates.

D. Pumping equipment shall be reciprocating pumps, preferably of the airoperated type, capable of developing at least 200 psi. Pumping rates and pressures shall be readily controlled. Under no conditions will "static head" type pumps be allowed.

E. Metals used for the construction of the mixers and pumps shall be compatible with the chemical system used in accordance with the chemical manufacturer's recommendations.

F. All equipment shall be cleaned of oil or other rust inhibitors prior to its contact with the grout constituents.

PART 3: EXECUTION

3.01 PREPARATION
A. Core or drill through existing interior slab-on-grade where required for placement of injection points.

3.02 MIXING AND PUMPING
A. All material shall be accurately measured by weight or volume for mixing. If a proportioning pump system is used, positive controls shall be incorporated to ensure accurate proportioning.

B. Care shall be taken not to contaminate mixing vessels with reactive chemicals by spillage, splash, etc.
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Section 6, Item # 6.1
C. A fast check reaction shall be made by the Contractor with each new primary batch. A test sample shall be made of every injection batch. If a proportioning system is used, a test sample shall be made periodically as required by the City or Engineer. The contractor shall keep records to establish the point of injection for each sample.

D. If any sample fails to show the proper stabilization, the potential area of failure shall be reinjected as directed by the Engineer.

E. Care shall be taken in the placing of injection points to secure accurate injection and the proper overlapping of injection cylinders.

F. Grouting Method: Injection grouting shall be done by the split-spaced, descending stage method. Grout injection points will be installed at the angles, depths, and spacing required to achieve permeation within the lines and grades shown on the drawings. Primary injection points shall be installed midway between the primary points.

Injection points shall be grouted in stages at intervals and depths selected by the contractor. Grouting will not be permitted in a secondary point until the adjacent primary points are completed.

If the contractor elects to grout using the sleeve pipe method, the injection tubes shall be installed and grouted first. After the grout around the pipe gains sufficient strength, chemical grouting may proceed.

G. Injection rates and pressures shall be closely controlled to prevent blowout, localized "quick" conditions, movement of immediately adjacent structures, and to ensure proper filling of voids to attain the desired stabilized section.

H. Quantities of grout injected at each point shall be governed by calculated volume, back pressure, or a combination of these two factors. If it appears at any point that a large void exists, proper steps shall be taken to assure penetration of the desired soil section.

I. If any injection batches begin to show signs of gelation, increased viscosity before injection, they shall immediately be discarded and equipment cleaned before proceeding further.

3.03 PATCHING
A. Replace floor slab to match existing dimensions.
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Section 6, Item # 6.1

3.04 QUALITY CONTROL AND MONITORING
A. One sample injection shall be made at a location designated by the engineer, and after suitable curing time, the sample shall be cored to collect samples for confirmation strength tests.

The contractor shall keep a daily log of grouting operations which shall contain the point number, location, grouting pressure, depth, grout mix proportions, and grout quantity.

B. Contractor shall monitor the existing building foundation and slab for excessive vertical movement. If excessive movement is observed the contractor shall stop injection at that location.

3.05 SUBMITALS
Contractor shall submit to the City and Engineer for review and approval the following submittals at least 7 days prior to start of injection grouting:

A) Grout mix design. Includes material data sheets, and laboratory compression tests on samples demonstrating the proposed mix will results in the required unconfined compressive strength.

B) Grouting plan. Plan should include as a minimum:
- Description of the mixing and proportioning methods and equipment. - Layout of grouting locations.
- Description of monitoring and quality control.
- Grouting procedure.

3.06 MEASUREMENT AND PAYMENT
A. Provide lump sum base bid based on total volume of grout below half the existing building and along the exterior edge of CLSM to an average depth of 10 feet below the floor slab. A unit price on a per-volume basis shall be provided for grouting for more than 10 feet.
23390105.CSS
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Section 6, Item # 6.1

Wheatland City CouncilFebruary 11, 2025

Wheatland City Council
February 11, 2025