Ninyo & Moore | Hidden Glen Dump, Coombsville Road, Napa, California | 109558001 | October 1, 2024 12 6 HAZARD MONITORING AND EQUIPMENT
If, odors, or other indications of possible contamination are observed, hand-held, direct-reading (real-time) instruments will be used to monitor air for VOCs, combustible gases, and/or dust at the site perimeter. Air monitoring will not be performed if odors or other indicators of contamination are not present.
The dust monitoring program will consist of the following activities: 1) monitoring for the presence of visible dust generated during earth moving activities; 2) if dust is observed, notify the contractor and request that dust be reduced/eliminated by appropriate engineering controls (e.g., application of water via hose, water truck, etc.); 3) use a portable monitoring instrument to measure total dust levels at the downwind perimeter of the site at an appropriate sampling frequency (e.g., approximately every half hour); and 4) document dust monitor readings, including date, time, and location of each measurement.
VOCs and LEL monitoring will be performed at the site perimeter during earthwork activities.
The monitoring equipment will consist of a direct-reading instrument for VOCs using a photoionization detector and combustible gases using a 4-gas meter, as applicable. Calibration of the instruments will be performed in accordance with the manufacturer’s specifications. If VOCs or LEL are detected above the action levels indicated in Section 6.2 of this plan engineering controls will be implemented to mitigate vapors and gases. Readings will be collected and documented similarly to the dust readings as described above.
6.1 Air Monitoring Procedures and Methodology
The Project Environmental Consultant will use aerosol monitoring equipment to monitor total dust at the work site perimeter and direct-reading instrument for VOCs and combustible gases.
The monitoring locations will be determined by the Project Environmental Consultant based on prevailing wind, project activities, and potential sensitive receptors. Air monitoring readings will be documented at approximately 30-minute intervals, unless modified by the Project Environmental Consultant.
A MiniRAM or other aerosol monitor that measures total airborne dust will be used to comply with the action level indicated below. A photoionization detector will be used to measure VOCs and a 4-gas meter will be used to measure combustible gases. Field personnel trained in proper calibration, use, and maintenance will calibrate equipment in accordance with the manufacturer’s specifications.
Ninyo & Moore | Hidden Glen Dump, Coombsville Road, Napa, California | 109558001 | October 1, 2024 13 Instrument readings collected for monitoring purposes will be recorded in a daily log by the Project Environmental Consultant. The log will include, at a minimum:
• Diagram indicating site boundaries, the areas of material disturbance, and the perimeter monitoring locations.
• Direct reading instruments listed above, including equipment make and model, serial number, and calibration record.
• Table of direct reading results including collection time and collection location. • Weather observations including time, wind direction, wind speed, temperature, and precipitation. • Other conditions or circumstances that may influence instrument readings.
When downwind direction cannot be determined or if wind direction varies throughout the day, the onsite Project Environmental Consultant personnel will use their best judgment to determine appropriate perimeter monitoring locations.
6.2 Action Levels for Perimeter Monitoring
The action level for air monitoring will be any visible dust or 1 milligram per cubic meter (mg/m3) measured with an aerosol monitor as measured at the site perimeter.
The action level for VOC and combustible gas monitoring will be greater than 2 parts per million (ppm) for VOCs sustained for over two minutes at the immediate work area perimeter or 10% LEL for combustible gases at the work activity.
The monitoring action levels for the site are provided in Table 1.
Table 1 – Direct Reading or Quantitative Sampling and Analysis Constituent Work Area Perimeter Action Level
Airborne dust Visible dust or 1 mg/m3 as measured with real-time instrument Total VOCs 2 ppm over background, sustained over 2 minutes Methane 10% of LEL at work activity
H2S 10 ppm at work activity
CO 10 ppm
Oxygen concentration (O2) < 19.5% O2 or > 22.0% O2
Notes:
LEL = lower explosive limit
mg/m3 = milligram per cubic meter
ug/m3 = microgram per cubic meter
Field personnel trained in proper calibration, use, and maintenance will calibrate direct air monitoring equipment in accordance with the manufacturer’s specifications.
Ninyo & Moore | Hidden Glen Dump, Coombsville Road, Napa, California | 109558001 | October 1, 2024 14
6.3 Action Plan to Reduce Airborne Concentrations
If the action level in Table 1 is exceeded, project activities will immediately cease until engineering controls are implemented to reduce airborne concentrations to below the action levels. Engineering controls and best management practices discussed in Section 5 of this document may be used by the Contractor to prevent exposure to the public; however, it will be the Contractor’s responsibility to select and provide effective dust suppression controls.
If the Contractor’s engineering controls fail to reduce airborne concentrations to below the action level, the Project Environmental Consultant will notify the District and request that work stop until options for effective controls to protect the community are evaluated and implemented. 7 CONTROL METHODS
Administrative and engineering controls will be implemented by the Contractor to prevent or minimize public exposure to potential hazards created by field activities. Control methods to reduce public access, prevent or minimize dust, and reduce noise and other physical hazards will be used. If other contamination hazards are observed by the Contractor during the course of work, the Project Environmental Consultant will be notified and appropriate assessments performed.
7.1 Site Security
Controlled areas will be established by the Contractor prior to commencement of construction activities at the site, using fencing or barricades. Only authorized personnel, with the proper training and personal protective equipment, will be allowed to enter any work area boundaries after they agree to abide by the provisions of the Contractor’s site-specific worker HSP, and are informed of potential dangers that could be encountered while onsite. Site workers will also be briefed on the requirements of this plan, where necessary for implementation. Work areas will be surrounded by construction fencing and pedestrian barricades and will be securely locked at the end of each work day to prevent unauthorized entry.
7.2 Dust and Debris Control
Soil-intrusive activities will likely generate airborne dust. Under certain atmospheric conditions, this dust may become a nuisance or a hazard to nearby sensitive receptors such as residential communities. Site personnel will visually monitor airborne dust and, if impacted soils/materials, the Project Environmental Consultant will document the results of perimeter monitoring during work in those areas. During activities that may create large quantities of dust, such as excavation and loading of trucks, implementation of strict dust control (e.g., watering or procedural change) will be undertaken by the Contractor. The Contractor will generally mitigate dust with water, applied by
Ninyo & Moore | Hidden Glen Dump, Coombsville Road, Napa, California | 109558001 | October 1, 2024 15 water trucks or hoses, in the active work areas. Best management practices to control run-on or run-off from the site will be used by the Contractor to ensure that contaminants not leave the site during storms or excessive water application.
Trucks carrying waste shall be enclosed such that there is no dust or odor during transportation along the haul route. Open trucks that may produce dust during transport will not be permitted to haul waste from the site.
7.3 VOCs and Combustible Gases Control
If VOCs or combustible gases are detected above the action levels at the site perimeter, work shall be stopped, the source of vapors and/or combustible gases shall be assessed and proper ventilation or vapor mitigation measures will be implemented. If mitigation measures fail to reduce airborne concentrations to below the action levels, the activity causing the exceedance will stop, the area will be secured and the City of Napa will be notified.
7.4 Stockpiled Soil
Soil stockpiles shall be maintained by the Contractor according to project plans, specifications, and Storm Water Pollution Prevention Plan (SWPPP), and all local, state, and federal regulations and requirements. Soil stockpiling procedures are detailed in the Remedial Action Plan develop by Ninyo & Moore concurrent with this CHSP.
7.5 Quality Assurance and Control Measures
Quality control and assurance measures will be implemented to ensure proper calibration of instrumentation, to document the use of appropriate sample collection and handling procedures, and to assess whether additional air monitoring and sampling is necessary.
All real-time instrumentation will be calibrated according to the manufacturer’s specifications prior to use each day. A record of this calibration will be logged on an appropriate form and will include: equipment manufacturer and model, serial number, factory calibration date and time, methodology, and results of the daily field calibration.
7.6 Best Management Practices
To minimize or prevent the discharge of contaminated or potentially contaminated materials from the subject site, best management practices will be implemented by the Contractor, and all local, state, and federal regulations regarding the handling, storage, transportation, and disposal of contaminated or potentially contaminated materials will be adhered to.
Ninyo & Moore | Hidden Glen Dump, Coombsville Road, Napa, California | 109558001 | October 1, 2024 16 Vehicles entering and/or exiting the site for loading of wastes and contaminated material slated for disposal shall be tracked by the Contractor through documentation and decontaminated (where applicable), prior to their departure from the site. Care shall be exercised to avoid spillage of contaminated materials from vehicles leaving the site.
In addition, the Contractor will contain, collect, treat, detain, test, and release site storm water and/or groundwater as required by the SWPPP, National Pollutant Discharge Elimination System (NPDES), and project plans and specifications.
8 EMERGENCY PLANNING
In the event of an emergency or unauthorized release of a hazardous substance or waste, the following actions will be taken:
In the event of a release that causes a sudden hazard to life or the environment, the Contractor’s Site Health and Safety Manager (SHSM) must be immediately contacted and informed of the health and/or environmental risk. These individuals have the knowledge and integrated authorities to cease any activity or condition contributing to the hazard.
The Contractor’s SHSM is also responsible for notifying the appropriate emergency response agencies and the District. The Contractor’s SHSM will be determined prior to commencement of construction activities, and the applicable contact names and numbers will be posted to report any hazards at the project site.
Other required actions include:
• Stop work activities, as necessary;
• Lower background noise to speed communication;
• Notify other site personnel;
• Begin emergency procedures as mentioned below; and
• Immediately contain the source and spread of the release per OSHA Hazardous Waste Operations and Emergency Response training.
If an injury or illness occurs:
• Get first aid for the injured person(s) immediately;
• Obtain professional medical attention if injury is serious; and • Notify the Contractor’s SHSO.
Ninyo & Moore | Hidden Glen Dump, Coombsville Road, Napa, California | 109558001 | October 1, 2024 17 Rescue and response actions should be decided and the necessary steps implemented. No one should attempt emergency rescue until qualified personnel and evacuation routes have been identified.
Following are local emergency telephone numbers:
GENERAL 911
FIRE Napa County Fire Department 911 or (707) 253-4940
HOSPITAL Providence Queen of the Valley Medical Center 911 or (707) 252-4411 POLICE City of Napa Police Department 911 or (707) 257-9223 9 PUBLIC NOTIFICATION
This Public Notice and Proposition 65 Warning are intended to advise the neighboring community of the planned activities. Prior to the initiation of project activities, the CHSP will be reviewed and approved by the LEA. Signs will be posted at the project entrance that provides the following:
• Project name;
• Project commencement and expected completion dates;
• Project-specific warnings,
• Any required Proposition 65 warnings; and
• Emergency contact information
Ninyo & Moore | Hidden Glen Dump, Coombsville Road, Napa, California | 109558001 | October 1, 2024 18 10 REFERENCES
Engeo, 1988, Geotechnical Exploration, Hidden Glenn – Fennell Property, Napa, California:
dated March 2.
Kunkel, F., and Upson, 1960, Geology and Groundwater in the Napa and Sonoma Valley areas.
U.S.G.S. Water Supply Paper 1495.
McClaren-Hart, Inc, 2000, Closure Plan Hidden Glen Landfill, Napa, California: dated April 6.
SCS Engineers, 2020, Property Management Plan for City-Owned Parcel (APN 045-411-022- 000), Investigation and Clean-Up of Closed Hidden Glen Landfill, Napa, California: dated March 2.
Ninyo & Moore | Hidden Glen Dump, Coombsville Road, Napa, California | 109558001 | October 1, 2024 Appendix A
Photographic Documentatio FIGURES n
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NOTE: DIRECTIONS, DIMENSIONS AND LOCATIONS ARE APPROXIMATE. | SOURCE: ESRI WORLD TOPO, 2024
SITE LOCATION
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FIGURE 1
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MAP INDEX
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HIDDEN GLEN DUMP
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SITE PLAN
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PARCEL A BOUNDARY APN: 045-411-022-000(SCS ENGINEERS, 2020) @
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Ninyo & Moore | Hidden Glen Dump, Coombsville Road, Napa, California | 109558001 | October 1, 2024 5710 Ruffin Road | San Diego, California 92123 | p. 858.576.1000 ARIZONA | CALIFORNIA | COLORADO | NEVADA | TEXAS | UTAH ninyoandmoore.com
Geotechnlcal & Environmental Sciences Consultants
Ninyo & Moore | Hidden Glen Dump, Coombsville Road, Napa, California | 109558001 | October 16, 2024
APPENDIX F
Alternative Acceptance of Neighboring Property Waste
Soil Grading Plans
RELOCATED SOIL WITH WASTE (TOTAL STOCKPILE DEBRIS = 2,753 CY)
SECTION CUT
EXISTING CONTOUR: 1'-0" INTERVAL TYP.
PROPOSED CONTOUR: 1'-0" INTERVAL TYP.
GRADING AND DRAINAGE NOTES
1. GRADING AND DRAINAGE: ALL PROPOSED PAVING, CURBS, WALLS, AND PLANTING AREAS SHALL SMOOTHLY CONFORM TO EXISTING ADJACENT FEATURES TO REMAIN. PROVIDE POSITIVE DRAINAGE ON ALL PAVING AND THROUGHOUT ALL PLANTING AREAS.
2. SOIL STOCKPILE: STRIP AND STOCKPILE EXISTING 6" LAYER OF SOIL FROM AREAS DISTURBED DURING GRADING OR EXCAVATION.
3. GRADING: CONTRACTOR SHALL PERFORM ALL EARTHWORK AND GRADING PER GEOTECHNICAL ENGINEER'S RECOMMENDATIONS.
4. LANDFILL CAP PROTECTION: REFER TO SPECIAL PROVISIONS SECTION 00 72 00 GENERAL REQUIREMENTS, SECTION 1.3.C FOR LANDFILL CAP PROTECTION REQUIREMENTS.
X
XX
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PASCALE PLACE
SD
SD
PGE
PG&E
SL
PASCALE PLACE
SD
SD
PGE
PG&E
SL
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126
125
128
125
126
127
129
130
137
138
139
140
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144
145
146
147
148
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150
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152
153
154
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132
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135
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136
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120
119
118
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114
113
112
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110
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REVISIONS
DESCRIPTION
DESCRIPTION:
ELEV.
BENCH MARK
DATE BY
HORIZ.
SCALE
15 HIDDEN GLEN DUMP REMEDIATION DRAWN BY:
DESIGNED BY:
CHECKED BY:
BS
MR
DATE
DATE
DATE
SHEET NO.
DRAWING NO.
CAD FILE:
DATE:
OF
VERT.
Callander Associates
Landscape Architecture
RH/OP
5/22/24
10/14/24
5/22/24
OCTOBER 14, 2024
1 5.0
A17058_GD_Accept all Debris.dwg
GRADING PLAN
0 20 feet
1" = 20'
40 NORTH
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EROSION CONTROL PLAN
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150'
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-230' -225' -220' -215' -210' -205' -200' -195' -190' -185' -180' -175' -170' -165' -160' -155' -150' -145' -140' -135' -130' -125' -120' -115' -110' -105' -100' -95' -85'-90' -80' -75' -65'-70' -60' -55' -45'-50' -40' -35' -25'-30' -20' -15' -10' -5' 0' 5'
APPROXIMATE LIMIT OF LANDFILL CAP
PROPERTY LINE
EX. GEOCOMPOSITE DRAINAGE NET &
POLYETHYLENE MEMBRANE
EX. GRADE
EX. TOP SOIL
EX. WASTE
EX. FOUNDATION FILL (18" MIN.)
SOIL WITH WASTE FILL, SEE
WASTE EXCAVATION PLAN
135'
145'
140'
150'
130'
155'
LOT 6
125'
120'
0' 5' 10' 15' 20' 25' 30' 40'35' 45' 50' 55' 65'60' 70' 85'80' 90' 95' 105'100' 110' 115' 125'120' 130' 135' 145'140' 150' 155' 165'160' 170' 175' 180' 185' 190' 195' 205'200' 210' 215' 225'220' 230' 235' 240' 245' 250' 255' 260' 265' 270' 275' 280' 290' 295' 285' 300' 305' 310' 315' 320'
LIMIT OF WORK
325'
APPROXIMATE LIMIT
OF LANDFILL CAP PROPERTY LINE
EX. FENCE EX. BEDROCK
2% MIN SLOPE EX. GEOCOMPOSITE DRAINAGE
NET & POLYETHYLENE MEMBRANE
SOIL WITH WASTE FILL, SEE
WASTE EXCAVATION PLAN
2'-0" MIN. OF SOIL CAP 2% MIN SLOPE
EX. GRADE
EX. TOP SOIL
EX. FOUNDATION FILL
(18" MIN.)
EX. WASTE
APPROXIMATE LIMIT OF
LANDFILL CAP
330'
130'
140'
135'
145'
125'
150'
120'
115
-5' 0' 5' 10' 15' 20' 25' 30' 40'35' 45' 50' 55' 70'65'60' 75' 85'80' 90' 95' 105'100' 110' 115' 125'120' 130' 135' 145'140' 75'
LIMIT OF WORK
APPROXIMATE LIMIT OF
LANDFILL CAP
EX. BEDROCK
2% MIN SLOPE
2% MIN SLOPE
2'-0" MIN. OF SOIL CAP
SOIL WITH WASTE FILL, SEE
WASTE EXCAVATION PLAN
EX. GEOCOMPOSITE DRAINAGE
NET & POLYETHYLENE MEMBRANE
EX. WASTE
EX. FOUNDATION FILL (18" MIN.)
EX. TOP SOIL
EX. GRADE
APPROXIMATE LIMIT OF
LANDFILL CAP
PROPERTY LINE
EX. FENCE
EX. BEDROCK
2'-0" MIN. OF SOIL CAP
EX. BEDROCK
160'
2 t:\Projects\2017 projects\17058_hiddenglenpark\3_constructiondocuments\CutFill\A17058_GD_Accept all Debris.dwg NO.
REVISIONS
DESCRIPTION
DESCRIPTION:
ELEV.
BENCH MARK
DATE BY
HORIZ.
SCALE
15 HIDDEN GLEN DUMP REMEDIATION DRAWN BY:
DESIGNED BY:
CHECKED BY:
BS
MR
DATE
DATE
DATE
SHEET NO.
DRAWING NO.
CAD FILE:
DATE:
OF
VERT.
Callander Associates
Landscape Architecture
RH/OP
5/22/24
10/14/24
5/22/24
OCTOBER 14, 2024
5.1 A17058_GD_Accept all Debris.dwg
2 SECTIONS
HIDDEN GLEN DUMP REMEDIATION- ALL WASTE
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APPENDIX G
DTSC Information Advisory – Clean Imported Fill
October 2001
ltisDTSC's
mission to restore,
protect and
enhance the
environment, to
ensure public
health,
environmental
quality and
economic vitality,
by regulating
hazardous waste,
conducting and
overseeing
cleanups, and
developing and
promoting
pollution
prevention.
State of California
California
Environmental
Protection Agency
e
Information Advisory
Clean Imported Fill Material
DEPARTMENT OF Toxic SussTANCES CONTROL
Executive Summary
This fact sheet has been prepared to ensure that inappropriate fill material is not introduced onto sensitive land use properties under the oversight of the DTSC or applicable regulatory authorities. Sensitive land use properties include those that contain facilities such as hospitals, homes, day care centers, and schools. This document only focuses on human health concerns and ecological issues are not addressed.
It identifies those types of land use activities that may be appropriate when determining whether a site may be used as a fill material source area. It also provides guidelines for the appropriate types of analyses that should be performed relative to the former land use, and for the number of samples that should be collected and analyzed based on the estimated volume of fill material that will need to be used The information provided in this fact sheet is not regulatory in nature, rather is to be used as a guide, and in most situations the final decision as to the acceptability of fill material for a sensitive land use property is made on a case-by-case basis by the appropriate regulatory agency.
Introduction
The use of imported fill material has recently come under scrutiny because of the instances where contaminated soil has been brought onto an otherwise clean site. However, there are currently no established standards in the statutes or regulations that address environmental requirements for imported fill material.
Therefore, the California Environmental Protection Agency, Department of Toxic Substances Control (DTSC) has prepared this fact sheet to identify procedures that can be used to minimize the possibility of introducing contaminated soil onto a site that requires imported fill material. Such sites include those that are undergoing site remediation, corrective action, and closure activities overseen by DTSC or the appropriate regulatory agency. These procedures may also apply to construction projects that will result in sensitive land uses. The intent of this fact sheet is to protect people who live on or otherwise use a sensitive land use property. By using this fact sheet as a guide, the reader will minimize the chance of introducing fill material that may result in potential risk to human health or the environment at some future time.
The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways you can reduce demand and cut your energy costs, see our website at www.dtsc.ca.gov.
Overview
Both natural and manmade fill materials are used
for a variety of purposes. Fill material properties are commonly controlled to meet the necessary site specific engineering specifications. Because most sites requiring fill material are located in or near urban
areas, the fill materials are often obtained from construction projects that generate an excess of soil, and from demolition debris (asphalt, broken concrete,
etc.). However, materials from those types of sites
may or may not be appropriate, depending on the
proposed use of the fill, and the quality of the assessment and/or mitigation measures, if necessary.
Therefore, unless material from construction
projects can be demonstrated to be free of contamination and/or appropriate for the proposed use, the use of that material as fill should be avoided.
Selecting Fill Material
In general, the fill source area should be located in
nonindustrial areas, and not from sites undergoing
an environmental cleanup. Nonindustrial sites include those that were previously undeveloped, or used solely for residential or agricultural purposes.
If the source is from an agricultural area, care should be taken to insure that the fill does not include
former agricultural waste process byproducts such
as manure or other decomposed organic material.
Undesirable sources of fill material include industrial and/or commercial sites where hazardous maPotential Contaminants Based on the Fill Source Area Fill Source:
Land near to an existing freeway
Land near a mining area or rock quarry
Agricultural land
Residential/acceptable commercial land
Target Compounds
Lead (EPA methods 6010B or 7471A), PAHs
(EPA method 8310)
Heavy Metals (EPA methods 601 OB and
7 4 71 A), asbestos (polarized light
microscopy), pH
Pesticides (Organochlorine Pesticides: EPA
method 8081 A or 8080A; Organophosphorus Pesticides: EPA method 8141 A; Chlorinated Herbicides: EPA method 8151 A), heavy metals (EPA methods 601 OB and
7471A)
VOCs (EPA method 8021 or 8260B, as
appropriate and combined with collection
by EPA Method 5035), semi-VOCs (EPA
method 8270C), TPH (modified EPA method
8015), PCBs (EPA method 8082 or 8080A),
heavy metals including lead (EPA methods
601 OB and 7 4 71 A), asbestos (OSHA Method
ID-191)
*The recommended analyses should be performed in accordance with USEPA SW-846 methods (J 996).
Other possible analyses include Hexavalent Chromium: EPA method 7199 II
Recommended Fill Material Sampling Schedule
Area of Individual Borrow Area
2 acres or less
2 to 4 acres
4 to 10 acres
Greater than 10 acres
Volume of Borrow Area Stockpile
Up to 1,000 cubic yards
1,000 to 5,000 cubic yards
Greater than 5,000 cubic yards
terials were used, handled or stored as part of the
business operations, or unpaved parking areas where
petroleum hydrocarbons could have been spilled or
leaked into the soil. Undesirable commercial sites
include former gasoline service stations, retail strip
malls that contained dry cleaners or photographic
processing facilities, paint stores, auto repair and/or painting facilities. Undesirable industrial facilities
include metal processing shops, manufacturing facilities, aerospace facilities, oil refineries, waste treatment plants, etc. Alternatives to using fill from construction sites include the use of fill material obtained from a commercial supplier of fill material or from soil pits in rural or suburban areas. However, care should be taken to ensure that those materials are also uncontaminated.
Documentation and Analysis
In order to minimize the potential of introducing
contaminated fill material onto a site, it is necessary II
Sampling Requirements
Minimum of 4 samples
Minimum of 1 sample every 1/2 acre
Minimum of 8 samples
Minimum of 8 locations with 4 subsamples
per location
Samples per Volume
1 sample per 250 cubic yards
4 samples for first 1000 cubic yards + 1
sample per each additional 500 cubic yards
12 samples for first 5,000 cubic yards + 1
sample per each additional 1,000 cubic
yards
to verify through documentation that the fill source
is appropriate and/or to have the fill material analyzed for potential contaminants based on the location and history of the source area. Fill documentation should include detailed information on the previous use of the land from where the fill is taken, whether an environmental site assessment was performed and its findings, and the results of any testing performed. It is recommended that any such documentation should be signed by an appropriately licensed (CA-registered) individual. If such documentation is not available or is inadequate,
samples of the fill material should be chemically analyzed. Analysis of the fill material should be based on the source of the fill and knowledge of the prior
land use.
Detectable amounts of compounds of concern
within the fill material should be evaluated for risk
in accordance with the DTSC Preliminary Endangerment Assessment {PEA) Guidance Manual. If
metal analyses are performed, only those metals
(CAM 17 /Title 22) to which risk levels have been
assigned need to be evaluated. At present, the
DTSC is working to establish California Screening Levels (CSL) to determine whether some compounds of concern pose a risk. Until such time as these CSL values are established, DTSC recommends that the DTSC PEA Guidance Manual or an equivalent process be referenced. This guidance may include the Regional Water Quality Control Board's (RWQCB) guidelines for reuse
of non-hazardous petroleum hydrocarbon contaminated soil as applied to Total Petroleum Hydrocarbons (TPH) only. The RWQCB guidelines should not be used for volatile organic compounds
(VOCs) or semi-volatile organic compounds
(SVOCS). In addition, a standard laboratory data
package, including a summary of the QA/QC
(Quality Assurance/Quality Control) sample results should also accompany all analytical reports.
When possible, representative samples should be collected at the borrow area while the potential fill material is still in place, and analyzed prior to removal from the borrow area. In addition to performing
the appropriate analyses of the fill material, an appropriate number of samples should also be determined based on the approximate volume or area of soil to be used as fill material. The table above can
be used as a guide to determine the number of
samples needed to adequately characterize the fill
material when sampled at the borrow site.
Alternative Sampling
A Phase I or PEA may be conducted prior to sampling to determine whether the borrow area may have been impacted by previous activities on the
property. After the property has been evaluated, any
sampling that may be required can be determined
during a meeting with DTSC or appropriate regulatory agency. However, if it is not possible to analyze the fill material at the borrow area or determine that it is appropriate for use via a Phase I or PEA, it is recommended that one (1) sample per
truckload be collected and analyzed for all comII
pounds of concern to ensure that the imported soil
is uncontaminated and acceptable. (See chart on
Potential Contaminants Based on the Fill Source
Area for appropriate analyses) . This sampling frequency may be modified upon consultation with the DTSC or appropriate regulatory agency if all of
the fill material is derived from a common borrow
area. However, fill material that is not characterized
at the borrow area will need to be stockpiled either
on or off-site until the analyses have been completed.
In addition, should contaminants exceeding acceptance criteria be identified in the stockpiled fill material, that material will be deemed unacceptable
and new fill material will need to be obtained,
sampled and analyzed. Therefore, the DTSC recommends that all sampling and analyses should be completed prior to delivery to the site to ensure the
soil is free of contamination, and to eliminate unnecessary transportation charges for unacceptable fill material.
Composite sampling for fill material characterization may or may not be appropriate, depending on quality and homogeneity of source/borrow area, and
compounds of concern. Compositing samples for
volatile and semivolatile constituents is not acceptable. Composite sampling for heavy metals, pesticides, herbicides or PAH's from unanalyzed stockpiled soil is also unacceptable, unless it is stockpiled at the borrow area and originates from the same
source area. In addition, if samples are composited,
they should be from the same soil layer, and not
from different soil layers.
When very large volumes of fill material are anticipated, or when larger areas are being considered as borrow areas, the DTSC recommends that a Phase
I or PEA be conducted on the area to ensure that
the borrow area has not been impacted by previous
activities on the property. After the property has
been evaluated, any sampling that may be required
can be determined during a meeting with the
DTSC.
For further information, call Richard Coffman, Ph.D.,
RG., at (818) 551-2175.
5710 Ruffin Road | San Diego, California 92123 | p. 858.576.1000 ARIZONA | CALIFORNIA | COLORADO | NEVADA | TEXAS | UTAH ninyoandmoore.com
Geotechnical & Environmental Sciences Consultants
APPENDIX C
AIR QUALITY, GREENHOUSE GAS EMISSIONS, & ENERGY
SUPPORTING INFORMATION
Napa Hidden Glenn
CalEEMod Version 2022.1.1.29 Inputs
Project Characteristics
Start of Construction: August 1, 2025
End of Construction: October 30, 2025
Location: Napa County
Air District: Bay Area Air Quality Management District
Utility Company: Pacific Gas & Electric (Electricity)
Project Specifics
No existing buildings will be demolished.
The project site is 2.18-acres.
The project would require 3,500 cubic yards of waste soil export using 18.5-ton capacity haul trucks. Waste soil would be transported to Kettleman Hills Class I non-RCRA hazardous waste landfill (470 miles per round trip and involve 25 percent of the soil export trips) and Altamont Class II non-hazardous waste landfill (146 miles per roundtrip and involve 75 percent of the soil export trips). Therefore, there would be 71 round trips to Kettleman Hills and 213 round trips to Altamont. The average round trip would be 227 miles. As a result, there would be a total of 284 round trips of waste soil export with a total of 64,468 miles traveled.
The project would require 6,050 cubic yards of clean soil fill using a combination of 18.5-ton capacity haul trucks and 12-ton haul trucks. Each round trip would be 16 miles. As a result, there would be a total of 595 round trips of clean soil fill import with a total of 9,520 miles traveled.
The project would require approximately ten construction workers per day. Typically, construction activities would occur between 8 a.m. and 5 p.m. (eight hours per day), on Monday through Friday.
On-Road fugitive dust inputs left as default.
Estimated Construction Schedule
Description Start End Hours per Day Working Days
Mobilization 8/1/2025 8/14/2025 5 10
Grading 8/15/2025 9/11/2025 5 20
Clean Fill Import 9/12/2025 10/16/2025 5 25
Restoration 10/17/2025 10/30/2025 5 10
SOURCE: Applicant Data Response (March 11, 2025).
Estimated Construction Equipment Usage
Phase Equipment Amoun
t
Daily
Hours HP LF
Mobilization Graders 1 8 148 0.41
Mobilization Scrapers 1 8 423 0.48
Mobilization Tractors/Loaders/Backhoes 1 7 84 0.37
Grading Graders 1 8 148 0.41
Grading Rubber Tired Dozers 1 8 367 0.40
Grading Tractors/Loaders/Backhoes 2 7 84 0.37
Grading Excavators 2 8 36 0.38
Grading Plate Compactors 1 8 8 0.43
Clean Fill Import Tractors/Loaders/Backhoes 2 7 84 0.37 Clean Fill Import Graders 1 8 148 0.41
Clean Fill Import Rubber Tired Dozers 1 8 367 0.4
Restoration Graders 1 8 148 0.41
Restoration Scrapers 1 8 423 0.48
Restoration Tractors/Loaders/Backhoes 1 7 84 0.37
SOURCE: Applicant Data Response (March 11, 2025) and CARB CalEEMod Version 2022.1.
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Napa Hidden Glenn Custom Report
Table of Contents
1. Basic Project Information
1.1. Basic Project Information
1.2. Land Use Types
1.3. User-Selected Emission Reduction Measures by Emissions Sector
2. Emissions Summary
2.1. Construction Emissions Compared Against Thresholds
2.2. Construction Emissions by Year, Unmitigated
3. Construction Emissions Details
3.1. Mobilization (2025) - Unmitigated
3.3. Restoration (2025) - Unmitigated
3.5. Grading (2025) - Unmitigated
3.7. Clean Fill Import (2025) - Unmitigated
4. Operations Emissions Details
4.10. Soil Carbon Accumulation By Vegetation Type
4.10.1. Soil Carbon Accumulation By Vegetation Type - Unmitigated
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4.10.2. Above and Belowground Carbon Accumulation by Land Use Type - Unmitigated
4.10.3. Avoided and Sequestered Emissions by Species - Unmitigated
5. Activity Data
5.1. Construction Schedule
5.2. Off-Road Equipment
5.2.1. Unmitigated
5.3. Construction Vehicles
5.3.1. Unmitigated
5.4. Vehicles
5.4.1. Construction Vehicle Control Strategies
5.5. Architectural Coatings
5.6. Dust Mitigation
5.6.1. Construction Earthmoving Activities
5.6.2. Construction Earthmoving Control Strategies
5.7. Construction Paving
5.8. Construction Electricity Consumption and Emissions Factors
5.18. Vegetation
5.18.1. Land Use Change
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5.18.1.1. Unmitigated
5.18.1. Biomass Cover Type
5.18.1.1. Unmitigated
5.18.2. Sequestration
5.18.2.1. Unmitigated
6. Climate Risk Detailed Report
6.1. Climate Risk Summary
6.2. Initial Climate Risk Scores
6.3. Adjusted Climate Risk Scores
7. Health and Equity Details
7.1. CalEnviroScreen 4.0 Scores
7.2. Healthy Places Index Scores
7.3. Overall Health & Equity Scores
7.4. Health & Equity Measures
7.5. Evaluation Scorecard
7.6. Health & Equity Custom Measures
8. User Changes to Default Data
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1. Basic Project Information
1.1. Basic Project Information
Data Field Value
Project Name Napa Hidden Glenn
Construction Start Date 8/4/2025
Lead Agency City of Napa
Land Use Scale Project/site
Analysis Level for Defaults County
Windspeed (m/s) 3.60
Precipitation (days) 42.2
Location 38.297890785929496, -122.26649688813013
County Napa
City Napa
Air District Bay Area AQMD
Air Basin San Francisco Bay Area
TAZ 805
EDFZ 2
Electric Utility Pacific Gas & Electric Company
Gas Utility Pacific Gas & Electric
App Version 2022.1.1.29
1.2. Land Use Types
Land Use Subtype Size Unit Lot Acreage Building Area (sq ft) Landscape Area (sq ft)
Special Landscape
Area (sq ft)
Population Description
City Park 2.18 Acre 2.18 0.00 2.18 2.18 — —
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1.3. User-Selected Emission Reduction Measures by Emissions Sector No measures selected
2. Emissions Summary
2.1. Construction Emissions Compared Against Thresholds Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Un/Mit. TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Unmit. 2.46 1.90 22.8 19.6 0.06 0.81 4.39 5.20 0.72 1.78 2.50 — 8,675 8,675 0.34 0.96 13.3 8,982 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Unmit. 1.95 1.61 15.3 15.8 0.03 0.66 3.11 3.76 0.60 1.42 2.02 — 3,329 3,329 0.14 0.14 0.06 3,375 Average
Daily
(Max)
— — — — — — — — — — — — — — — — — —
Unmit. 0.35 0.28 2.91 2.79 0.01 0.12 0.49 0.61 0.10 0.20 0.30 — 861 861 0.03 0.06 0.40 881 Annual
(Max)
— — — — — — — — — — — — — — — — — —
Unmit. 0.06 0.05 0.53 0.51 < 0.005 0.02 0.09 0.11 0.02 0.04 0.06 — 142 142 0.01 0.01 0.07 146
2.2. Construction Emissions by Year, Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Year TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily -
Summer
(Max)
— — — — — — — — — — — — — — — — — —
2025 2.46 1.90 22.8 19.6 0.06 0.81 4.39 5.20 0.72 1.78 2.50 — 8,675 8,675 0.34 0.96 13.3 8,982 -------------------
-------------------
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Daily -
Winter
(Max)
— — — — — — — — — — — — — — — — — —
2025 1.95 1.61 15.3 15.8 0.03 0.66 3.11 3.76 0.60 1.42 2.02 — 3,329 3,329 0.14 0.14 0.06 3,375 Average
Daily
— — — — — — — — — — — — — — — — — —
2025 0.35 0.28 2.91 2.79 0.01 0.12 0.49 0.61 0.10 0.20 0.30 — 861 861 0.03 0.06 0.40 881 Annual — — — — — — — — — — — — — — — — — —
2025 0.06 0.05 0.53 0.51 < 0.005 0.02 0.09 0.11 0.02 0.04 0.06 — 142 142 0.01 0.01 0.07 146
3. Construction Emissions Details
3.1. Mobilization (2025) - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Onsite — — — — — — — — — — — — — — — — — —
Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent
1.42 1.19 10.9 11.0 0.03 0.47 — 0.47 0.43 — 0.43 — 2,717 2,717 0.11 0.02 — 2,726 Dust
From
Material
Movement
— — — — — — 0.62 0.62 — 0.07 0.07 — — — — — — —
Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Average
Daily
— — — — — — — — — — — — — — — — — —
-------------------
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Off-Roa
Equipment
0.04 0.03 0.30 0.30 < 0.005 0.01 — 0.01 0.01 — 0.01 — 74.4 74.4 < 0.005 < 0.005 — 74.7 Dust
From
Material
Movement
— — — — — — 0.02 0.02 — < 0.005 < 0.005 — — — — — — —
Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Annual — — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent
0.01 0.01 0.05 0.05 < 0.005 < 0.005 — < 0.005 < 0.005 — < 0.005 — 12.3 12.3 < 0.005 < 0.005 — 12.4 Dust
From
Material
Movement
— — — — — — < 0.005 < 0.005 — < 0.005 < 0.005 — — — — — — — Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Offsite — — — — — — — — — — — — — — — — — —
Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.09 0.08 0.06 0.92 0.00 0.00 0.17 0.17 0.00 0.04 0.04 — 173 173 < 0.005 0.01 0.74 176 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Average
Daily
— — — — — — — — — — — — — — — — — —
Worker < 0.005 < 0.005 < 0.005 0.02 0.00 0.00 < 0.005 < 0.005 0.00 < 0.005 < 0.005 — 4.47 4.47 < 0.005 < 0.005 0.01 4.54 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Annual — — — — — — — — Page 263 of 342 — — — — — — — — — — ATTACHMENT 6
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Worker < 0.005 < 0.005 < 0.005 < 0.005 0.00 0.00 < 0.005 < 0.005 0.00 < 0.005 < 0.005 — 0.74 0.74 < 0.005 < 0.005 < 0.005 0.75 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00
3.3. Restoration (2025) - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Onsite — — — — — — — — — — — — — — — — — —
Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent
1.42 1.19 10.9 11.0 0.03 0.47 — 0.47 0.43 — 0.43 — 2,717 2,717 0.11 0.02 — 2,726 Dust
From
Material
Movement
— — — — — — 0.62 0.62 — 0.07 0.07 — — — — — — —
Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Average
Daily
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent
0.04 0.03 0.30 0.30 < 0.005 0.01 — 0.01 0.01 — 0.01 — 74.4 74.4 < 0.005 < 0.005 — 74.7 Dust
From
Material
Movement
— — — — — — 0.02 0.02 — < 0.005 < 0.005 — — — — — — —
-------------------
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Onsite 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 truck
Annual — — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent
0.01 0.01 0.05 0.05 < 0.005 < 0.005 — < 0.005 < 0.005 — < 0.005 — 12.3 12.3 < 0.005 < 0.005 — 12.4 Dust
From
Material
Movement
— — — — — — < 0.005 < 0.005 — < 0.005 < 0.005 — — — — — — — Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Offsite — — — — — — — — — — — — — — — — — —
Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.09 0.08 0.08 0.84 0.00 0.00 0.17 0.17 0.00 0.04 0.04 — 162 162 0.01 0.01 0.02 164 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Average
Daily
— — — — — — — — — — — — — — — — — —
Worker < 0.005 < 0.005 < 0.005 0.02 0.00 0.00 < 0.005 < 0.005 0.00 < 0.005 < 0.005 — 4.47 4.47 < 0.005 < 0.005 0.01 4.54 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Annual — — — — — — — — — — — — — — — — — —
Worker < 0.005 < 0.005 < 0.005 < 0.005 0.00 0.00 < 0.005 < 0.005 0.00 < 0.005 < 0.005 — 0.74 0.74 < 0.005 < 0.005 < 0.005 0.75 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00
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3.5. Grading (2025) - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Onsite — — — — — — — — — — — — — — — — — —
Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent
2.07 1.74 16.0 16.8 0.03 0.70 — 0.70 0.65 — 0.65 — 2,772 2,772 0.11 0.02 — 2,782 Dust
From
Material
Movement
— — — — — — 2.77 2.77 — 1.34 1.34 — — — — — — —
Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Average
Daily
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent
0.11 0.10 0.88 0.92 < 0.005 0.04 — 0.04 0.04 — 0.04 — 152 152 0.01 < 0.005 — 152 Dust
From
Material
Movement
— — — — — — 0.15 0.15 — 0.07 0.07 — — — — — — —
Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Annual — — — — — — — — — — — — — — — — — —
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Off-Roa 0.02 0.02 0.16 0.17 < 0.005 0.01 — 0.01 0.01 — 0.01 — 25.2 25.2 < 0.005 < 0.005 — 25.2 d
Equipm
ent
Dust
From
Material
Movement
— — — — — — 0.03 0.03 — 0.01 0.01 — — — — — — —
Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Offsite — — — — — — — — — — — — — — — — — —
Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.09 0.08 0.06 0.92 0.00 0.00 0.17 0.17 0.00 0.04 0.04 — 173 173 < 0.005 0.01 0.74 176 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling 0.30 0.08 6.74 1.91 0.04 0.11 1.46 1.57 0.07 0.41 0.48 — 5,729 5,729 0.22 0.93 12.6 6,024 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Average
Daily
— — — — — — — — — — — — — — — — — —
Worker < 0.005 < 0.005 < 0.005 0.04 0.00 0.00 0.01 0.01 0.00 < 0.005 < 0.005 — 8.94 8.94 < 0.005 < 0.005 0.02 9.08 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling 0.02 < 0.005 0.39 0.10 < 0.005 0.01 0.08 0.08 < 0.005 0.02 0.03 — 314 314 0.01 0.05 0.30 330 Annual — — — — — — — — — — — — — — — — — —
Worker < 0.005 < 0.005 < 0.005 0.01 0.00 0.00 < 0.005 < 0.005 0.00 < 0.005 < 0.005 — 1.48 1.48 < 0.005 < 0.005 < 0.005 1.50 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling < 0.005 < 0.005 0.07 0.02 < 0.005 < 0.005 0.01 0.02 < 0.005 < 0.005 < 0.005 — 52.0 52.0 < 0.005 0.01 0.05 54.6
3.7. Clean Fill Import (2025) - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual)
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Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Onsite — — — — — — — — — — — — — — — — — —
Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent
1.80 1.51 14.1 14.5 0.02 0.64 — 0.64 0.59 — 0.59 — 2,455 2,455 0.10 0.02 — 2,463 Dust
From
Material
Movement
— — — — — — 2.77 2.77 — 1.34 1.34 — — — — — — —
Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent
1.80 1.51 14.1 14.5 0.02 0.64 — 0.64 0.59 — 0.59 — 2,455 2,455 0.10 0.02 — 2,463 Dust
From
Material
Movement
— — — — — — 2.77 2.77 — 1.34 1.34 — — — — — — —
Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Average
Daily
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent
0.12 0.10 0.96 0.99 < 0.005 0.04 — 0.04 0.04 — 0.04 — 168 168 0.01 < 0.005 — 169 Dust
From
Material
Movement
— — — — — — 0.19 0.19 — 0.09 0.09 — — — — — — —
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Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Annual — — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent
0.02 0.02 0.18 0.18 < 0.005 0.01 — 0.01 0.01 — 0.01 — 27.8 27.8 < 0.005 < 0.005 — 27.9 Dust
From
Material
Movement
— — — — — — 0.03 0.03 — 0.02 0.02 — — — — — — —
Onsite
truck
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Offsite — — — — — — — — — — — — — — — — — —
Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.09 0.08 0.06 0.92 0.00 0.00 0.17 0.17 0.00 0.04 0.04 — 173 173 < 0.005 0.01 0.74 176 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling 0.06 0.02 1.11 0.43 < 0.005 0.01 0.17 0.18 0.01 0.05 0.06 — 712 712 0.04 0.12 1.49 749 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.09 0.08 0.08 0.84 0.00 0.00 0.17 0.17 0.00 0.04 0.04 — 162 162 0.01 0.01 0.02 164 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling 0.06 0.02 1.17 0.44 < 0.005 0.01 0.17 0.18 0.01 0.05 0.06 — 712 712 0.04 0.12 0.04 748 Average
Daily
— — — — — — — — — — — — — — — — — —
Worker 0.01 0.01 < 0.005 0.06 0.00 0.00 0.01 0.01 0.00 < 0.005 < 0.005 — 11.2 11.2 < 0.005 < 0.005 0.02 11.3 Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling < 0.005 < 0.005 0.08 0.03 < 0.005 < 0.005 0.01 0.01 < 0.005 < 0.005 < 0.005 — 48.8 48.8 < 0.005 0.01 0.04 51.2 Annual — — — — — — — — — — — — — — — — — —
Worker < 0.005 < 0.005 < 0.005 0.01 0.00 0.00 < 0.005 < 0.005 0.00 < 0.005 < 0.005 — 1.85 1.85 < 0.005 < 0.005 < 0.005 1.88
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Vendor 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 — 0.00 0.00 0.00 0.00 0.00 0.00 Hauling < 0.005 < 0.005 0.01 0.01 < 0.005 < 0.005 < 0.005 < 0.005 < 0.005 < 0.005 < 0.005 — 8.07 8.07 < 0.005 < 0.005 0.01 8.48
4. Operations Emissions Details
4.10. Soil Carbon Accumulation By Vegetation Type
4.10.1. Soil Carbon Accumulation By Vegetation Type - Unmitigated Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Vegetati
on
TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Total — — — — — — — — — — — — — — — — — —
Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Total — — — — — — — — — — — — — — — — — —
Annual — — — — — — — — — — — — — — — — — —
Total — — — — — — — — — — — — — — — — — —
4.10.2. Above and Belowground Carbon Accumulation by Land Use Type - Unmitigated Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Land
Use
TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Total — — — — — — — — — — — — — — — — — —
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Daily, — — — — — — — — — — — — — — — — — —
Winter
(Max)
Total — — — — — — — — — — — — — — — — — —
Annual — — — — — — — — — — — — — — — — — —
Total — — — — — — — — — — — — — — — — — —
4.10.3. Avoided and Sequestered Emissions by Species - Unmitigated Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Species TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Avoided — — — — — — — — — — — — — — — — — —
Subtotal — — — — — — — — — — — — — — — — — —
Sequest
ered
— — — — — — — — — — — — — — — — — —
Subtotal — — — — — — — — — — — — — — — — — —
Remove
d
— — — — — — — — — — — — — — — — — —
Subtotal — — — — — — — — — — — — — — — — — —
— — — — — — — — — — — — — — — — — — —
Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Avoided — — — — — — — — — — — — — — — — — —
Subtotal — — — — — — — — — — — — — — — — — —
Sequest
ered
— — — — — — — — — — — — — — — — — —
Subtotal — — — — — — — — — — — — — — — — — —
Remove
d
— — — — — — — — — — — — — — — — — —
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Subtotal — — — — — — — — — — — — — — — — — —
— — — — — — — — — — — — — — — — — — —
Annual — — — — — — — — — — — — — — — — — —
Avoided — — — — — — — — — — — — — — — — — —
Subtotal — — — — — — — — — — — — — — — — — —
Sequest
ered
— — — — — — — — — — — — — — — — — —
Subtotal — — — — — — — — — — — — — — — — — —
Remove
d
— — — — — — — — — — — — — — — — — —
Subtotal — — — — — — — — — — — — — — — — — —
— — — — — — — — — — — — — — — — — — —
5. Activity Data
5.1. Construction Schedule
Phase Name Phase Type Start Date End Date Days Per Week Work Days per Phase Phase Description Mobilization Site Preparation 8/1/2025 8/14/2025 5.00 10.0 1 Restoration Site Preparation 10/17/2025 10/30/2025 5.00 10.0 4 Grading Grading 8/15/2025 9/11/2025 5.00 20.0 2
Clean Fill Import Grading 9/12/2025 10/16/2025 5.00 25.0 3
5.2. Off-Road Equipment
5.2.1. Unmitigated
Phase Name Equipment Type Fuel Type Engine Tier Number per Day Hours Per Day Horsepower Load Factor Mobilization Graders Diesel Average 1.00 8.00 148 0.41
Mobilization Scrapers Diesel Average 1.00 8.00 423 0.48
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Mobilization Tractors/Loaders/Back Diesel Average 1.00 7.00 84.0 0.37 Restoration Graders Diesel Average 1.00 8.00 148 0.41
Restoration Scrapers Diesel Average 1.00 8.00 423 0.48
Restoration Tractors/Loaders/Back
hoes
Diesel Average 1.00 7.00 84.0 0.37
Grading Graders Diesel Average 1.00 8.00 148 0.41
Grading Rubber Tired Dozers Diesel Average 1.00 8.00 367 0.40 Grading Tractors/Loaders/Back
hoes
Diesel Average 2.00 7.00 84.0 0.37
Grading Excavators Diesel Average 2.00 8.00 36.0 0.38
Grading Plate Compactors Diesel Average 1.00 8.00 8.00 0.43 Clean Fill Import Tractors/Loaders/Back
hoes
Diesel Average 2.00 7.00 84.0 0.37
Clean Fill Import Graders Diesel Average 1.00 8.00 148 0.41 Clean Fill Import Rubber Tired Dozers Diesel Average 1.00 8.00 367 0.40
5.3. Construction Vehicles
5.3.1. Unmitigated
Phase Name Trip Type One-Way Trips per Day Miles per Trip Vehicle Mix Mobilization — — — —
Mobilization Worker 20.0 11.7 LDA,LDT1,LDT2
Mobilization Vendor 0.00 8.40 HHDT,MHDT
Mobilization Hauling 0.00 20.0 HHDT
Mobilization Onsite truck 0.00 — HHDT
Grading — — — —
Grading Worker 20.0 11.7 LDA,LDT1,LDT2
Grading Vendor 0.00 8.40 HHDT,MHDT
Grading Hauling 14.2 114 HHDT
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Grading Onsite truck 0.00 — HHDT
Clean Fill Import — — — —
Clean Fill Import Worker 20.0 11.7 LDA,LDT1,LDT2
Clean Fill Import Vendor 0.00 8.40 HHDT,MHDT
Clean Fill Import Hauling 23.8 8.00 HHDT
Clean Fill Import Onsite truck 0.00 — HHDT
Restoration — — — —
Restoration Worker 20.0 11.7 LDA,LDT1,LDT2
Restoration Vendor 0.00 8.40 HHDT,MHDT
Restoration Hauling 0.00 20.0 HHDT
Restoration Onsite truck 0.00 — HHDT
5.4. Vehicles
5.4.1. Construction Vehicle Control Strategies
Non-applicable. No control strategies activated by user.
5.5. Architectural Coatings
Phase Name Residential Interior Area
Coated (sq ft)
Residential Exterior Area
Coated (sq ft)
Non-Residential Interior Area
Coated (sq ft)
Non-Residential Exterior Area
Coated (sq ft)
Parking Area Coated (sq ft)
5.6. Dust Mitigation
5.6.1. Construction Earthmoving Activities
Phase Name Material Imported (Cubic
Yards)
Material Exported (Cubic
Yards)
Acres Graded (acres) Material Demolished (sq. ft.) Acres Paved (acres) Mobilization 0.00 0.00 15.0 0.00 —
Restoration 0.00 0.00 15.0 0.00 —
Grading 0.00 3,500 20.0 0.00 —
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Clean Fill Import 6,050 0.00 25.0 0.00 —
5.6.2. Construction Earthmoving Control Strategies
Control Strategies Applied Frequency (per day) PM10 Reduction PM2.5 Reduction Water Exposed Area 2 61% 61%
5.7. Construction Paving
Land Use Area Paved (acres) % Asphalt
City Park 0.00 0%
5.8. Construction Electricity Consumption and Emissions Factors kWh per Year and Emission Factor (lb/MWh)
Year kWh per Year CO2 CH4 N2O
2025 0.00 204 0.03 < 0.005
5.18. Vegetation
5.18.1. Land Use Change
5.18.1.1. Unmitigated
Vegetation Land Use Type Vegetation Soil Type Initial Acres Final Acres
5.18.1. Biomass Cover Type
5.18.1.1. Unmitigated
Biomass Cover Type Initial Acres Final Acres
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5.18.2. Sequestration
5.18.2.1. Unmitigated
Tree Type Number Electricity Saved (kWh/year) Natural Gas Saved (btu/year)
6. Climate Risk Detailed Report
6.1. Climate Risk Summary
Cal-Adapt midcentury 2040–2059 average projections for four hazards are reported below for your project location. These are under Representation Concentration Pathway (RCP) 8.5 which assumes GHG emissions will continue to rise strongly through 2050 and then plateau around 2100.
Climate Hazard Result for Project Location Unit
Temperature and Extreme Heat 11.4 annual days of extreme heat Extreme Precipitation 7.95 annual days with precipitation above 20 mm Sea Level Rise — meters of inundation depth
Wildfire 15.6 annual hectares burned
Temperature and Extreme Heat data are for grid cell in which your project are located. The projection is based on the 98th historical percentile of daily maximum/minimum temperatures from observed historical data (32 climate model ensemble from Cal-Adapt, 2040–2059 average under RCP 8.5). Each grid cell is 6 kilometers (km) by 6 km, or 3.7 miles (mi) by 3.7 mi.
Extreme Precipitation data are for the grid cell in which your project are located. The threshold of 20 mm is equivalent to about ¾ an inch of rain, which would be light to moderate rainfall if received over a full day or heavy rain if received over a period of 2 to 4 hours. Each grid cell is 6 kilometers (km) by 6 km, or 3.7 miles (mi) by 3.7 mi.
Sea Level Rise data are for the grid cell in which your project are located. The projections are from Radke et al. (2017), as reported in Cal-Adapt (Radke et al., 2017, CEC-500-2017-008), and consider inundation location and depth for the San Francisco Bay, the Sacramento-San Joaquin River Delta and California coast resulting different increments of sea level rise coupled with extreme storm events. Users may select from four scenarios to view the range in potential inundation depth for the grid cell. The four scenarios are: No rise, 0.5 meter, 1.0 meter, 1.41 meters Wildfire data are for the grid cell in which your project are located. The projections are from UC Davis, as reported in Cal-Adapt (2040–2059 average under RCP 8.5), and consider historical data of climate, vegetation, population density, and large (> 400 ha) fire history. Users may select from four model simulations to view the range in potential wildfire probabilities for the grid cell. The four simulations make different assumptions about expected rainfall and temperature are: Warmer/drier (HadGEM2-ES), Cooler/wetter (CNRM-CM5), Average conditions (CanESM2), Range of different rainfall and temperature possibilities (MIROC5). Each grid cell is 6 kilometers (km) by 6 km, or 3.7 miles (mi) by 3.7 mi.
6.2. Initial Climate Risk Scores
Climate Hazard Exposure Score Sensitivity Score Adaptive Capacity Score Vulnerability Score Temperature and Extreme Heat N/A N/A N/A N/A
Extreme Precipitation 2 0 0 N/A
Sea Level Rise 1 0
0 N/A
ATTACHMENT 6
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Wildfire 1 0 0 N/A
Flooding N/A N/A N/A N/A
Drought N/A N/A N/A N/A
Snowpack Reduction N/A N/A N/A N/A
Air Quality Degradation 0 0 0 N/A
The sensitivity score reflects the extent to which a project would be adversely affected by exposure to a climate hazard. Exposure is rated on a scale of 1 to 5, with a score of 5 representing the greatest exposure.
The adaptive capacity of a project refers to its ability to manage and reduce vulnerabilities from projected climate hazards. Adaptive capacity is rated on a scale of 1 to 5, with a score of 5 representing the greatest ability to adapt.
The overall vulnerability scores are calculated based on the potential impacts and adaptive capacity assessments for each hazard. Scores do not include implementation of climate risk reduction measures.
6.3. Adjusted Climate Risk Scores
Climate Hazard Exposure Score Sensitivity Score Adaptive Capacity Score Vulnerability Score Temperature and Extreme Heat N/A N/A N/A N/A
Extreme Precipitation 2 1 1 3
Sea Level Rise 1 1 1 2
Wildfire 1 1 1 2
Flooding N/A N/A N/A N/A
Drought N/A N/A N/A N/A
Snowpack Reduction N/A N/A N/A N/A
Air Quality Degradation 1 1 1 2
The sensitivity score reflects the extent to which a project would be adversely affected by exposure to a climate hazard. Exposure is rated on a scale of 1 to 5, with a score of 5 representing the greatest exposure.
The adaptive capacity of a project refers to its ability to manage and reduce vulnerabilities from projected climate hazards. Adaptive capacity is rated on a scale of 1 to 5, with a score of 5 representing the greatest ability to adapt.
The overall vulnerability scores are calculated based on the potential impacts and adaptive capacity assessments for each hazard. Scores include implementation of climate risk reduction measures.
7. Health and Equity Details
7.1. CalEnviroScreen 4.0 Scores
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The maximum CalEnviroScreen score is 100. A high score (i.e., greater than 50) reflects a higher pollution burden compared to other census tracts in the state.
Indicator Result for Project Census Tract
Exposure Indicators —
AQ-Ozone 20.8
AQ-PM 45.9
AQ-DPM 35.9
Drinking Water 43.0
Lead Risk Housing 46.3
Pesticides 66.6
Toxic Releases 54.5
Traffic 9.82
Effect Indicators —
CleanUp Sites 75.6
Groundwater 65.3
Haz Waste Facilities/Generators 7.35
Impaired Water Bodies 33.2
Solid Waste 70.4
Sensitive Population —
Asthma 32.2
Cardio-vascular 20.3
Low Birth Weights 13.5
Socioeconomic Factor Indicators —
Education 24.6
Housing 8.86
Linguistic 32.0
Poverty 22.0
Unemployment 0.00
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7.2. Healthy Places Index Scores
The maximum Health Places Index score is 100. A high score (i.e., greater than 50) reflects healthier community conditions compared to other census tracts in the state.
Indicator Result for Project Census Tract
Economic —
Above Poverty 76.32490697
Employed 85.83344027
Median HI 82.40728859
Education —
Bachelor's or higher 74.51559091
High school enrollment 16.64314128
Preschool enrollment 19.87681252
Transportation —
Auto Access 87.47593995
Active commuting 28.80790453
Social —
2-parent households 85.55113563
Voting 92.53175927
Neighborhood —
Alcohol availability 34.56948544
Park access 50.84049788
Retail density 16.54048505
Supermarket access 26.85743616
Tree canopy 95.09816502
Housing —
Homeownership 56.88438342
Housing habitability 91.81316566
Low-inc homeowner severe housing cost burden 84.04978827 Low-inc renter severe housing cost burden 93.46849737
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Uncrowded housing 68.66418581
Health Outcomes —
Insured adults 80.31566791
Arthritis 12.5
Asthma ER Admissions 61.0
High Blood Pressure 18.2
Cancer (excluding skin) 9.1
Asthma 51.9
Coronary Heart Disease 23.5
Chronic Obstructive Pulmonary Disease 37.6
Diagnosed Diabetes 70.5
Life Expectancy at Birth 71.8
Cognitively Disabled 28.0
Physically Disabled 68.4
Heart Attack ER Admissions 91.4
Mental Health Not Good 71.0
Chronic Kidney Disease 45.1
Obesity 54.6
Pedestrian Injuries 63.5
Physical Health Not Good 64.0
Stroke 45.2
Health Risk Behaviors —
Binge Drinking 32.5
Current Smoker 70.0
No Leisure Time for Physical Activity 75.4
Climate Change Exposures —
Wildfire Risk 0.0
SLR Inundation Area 74.5
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Children 78.7
Elderly 19.2
English Speaking 84.7
Foreign-born 26.1
Outdoor Workers 53.0
Climate Change Adaptive Capacity —
Impervious Surface Cover 79.2
Traffic Density 13.1
Traffic Access 49.0
Other Indices —
Hardship 18.0
Other Decision Support —
2016 Voting 96.1
7.3. Overall Health & Equity Scores
Metric Result for Project Census Tract
CalEnviroScreen 4.0 Score for Project Location (a) 15.0 Healthy Places Index Score for Project Location (b) 81.0 Project Located in a Designated Disadvantaged Community (Senate Bill 535) No Project Located in a Low-Income Community (Assembly Bill 1550) No Project Located in a Community Air Protection Program Community (Assembly Bill 617) No a: The maximum CalEnviroScreen score is 100. A high score (i.e., greater than 50) reflects a higher pollution burden compared to other census tracts in the state. b: The maximum Health Places Index score is 100. A high score (i.e., greater than 50) reflects healthier community conditions compared to other census tracts in the state.
7.4. Health & Equity Measures
No Health & Equity Measures selected.
7.5. Evaluation Scorecard
Health & Equity Evaluation Scorecard not completed.
Napa Hidden Glenn Custom Report, 4/9/2025
26 / 26
7.6. Health & Equity Custom Measures
No Health & Equity Custom Measures created.
8. User Changes to Default Data
Screen Justification
Construction: Construction Phases Applicant Data Responses March 11, 2025 Construction: Off-Road Equipment Applicant Data Response March 11, 2025 Construction: Dust From Material Movement Applicant Data Response March 11, 2025 Construction: Trips and VMT Applicant Data Response March 11, 2025
APPENDIX D
BIOLOGICAL RESOURCES ASSESSMENT
Biological Resources Assessment
Hidden Glen Remediation Project
City of Napa
April 2025
Prepared for:
City of Napa
1700 2nd Street, Suite 100
Napa, CA 94559
RCH Group
6521 Chesbro Circle
Rancho Murieta, CA 95683
Prepared by:
Swift Biological Consulting LLC
Sebastopol, CA 95472
https://swiftbiological.com/
~ SWIFT BIOLOGICAL
Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
Table of Contents
1 Introduction .......................................................................................................................... 1
1.1 Project Setting ............................................................................................................... 1
1.2 Proposed Project ........................................................................................................... 4 2 Methods ................................................................................................................................ 5
2.1 Background Review ....................................................................................................... 5
2.2 Biology Field Surveys ..................................................................................................... 6
2.3 Maps and Photographs .................................................................................................. 7 3 Existing Conditions ................................................................................................................ 8
3.1 Physical Characteristics .................................................................................................. 8
3.2 Existing Plant Communities ............................................................................................ 8
3.3 Wildlife Habitats .......................................................................................................... 10
3.4 Wildlife Connectivity .................................................................................................... 11 4 Special-status Species and Habitats ..................................................................................... 12
4.1 Special-status Species Definition .................................................................................. 12
4.2 Special-status Species Evaluation Criteria .................................................................... 12
4.3 Special-status Plants .................................................................................................... 13
4.4 Special-status Animals ................................................................................................. 15 5 Sensitive Natural Communities ............................................................................................ 19 6 Aquatic Resources ............................................................................................................... 20 7 Conclusions ......................................................................................................................... 21
7.1 Existing Plant Communities .......................................................................................... 21
7.2 Sensitive Natural Communities .................................................................................... 22
7.3 Aquatic Resources ....................................................................................................... 22
7.4 Special-status Plants .................................................................................................... 22
7.5 Special-status Animals ................................................................................................. 23
7.6 Nesting Birds ................................................................................................................ 23
7.7 Special-status Bats ....................................................................................................... 24 8 References ........................................................................................................................... 25 9 Photographs ........................................................................................................................ 28 10 Tables .............................................................................................................................. 37
Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
List of Figures
Figure 1. Project Location .............................................................................................................. 2 Figure 2. Site Map ......................................................................................................................... 3 Figure 3. California Natural Diversity Database Occurrences ....................................................... 14 List of Tables
Table 1. Plants Species Observed During Botanical Surveys, March – April 2025 ......................... 37 Table 2. Wildlife Species Observed During Botanical Surveys, March – April 2025 ...................... 38 Table 3. Special-status Plants Evaluated for Potential to Occur within the Project Site ................ 39 Table 4. Special-status Animals Evaluated for Potential to Occur within the Project Site ............. 43
Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
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1 Introduction
The City of Napa (the City) is proposing a remediation project at the Hidden Glen Dump near the intersection of Pascale Place and Glory Court in Napa, California. The dump is a City-owned property that was formerly a waste disposal site. During a 2018 site investigation, waste-impacted soils and high lead concentrations were detected, exceeding environmental standards. The City is proposing a remediation project to remove the contaminated soil and cover it with imported clean fill.
Swift Biological Consulting LLC (Swift Biological) was retained by RCH Group through a contract with the City of Napa to complete a biological resources assessment of the proposed remediation project. The purpose of this report is to identify sensitive biological communities and special-status species and their habitats within the project site1, evaluate potential impacts on sensitive resources resulting from the proposed project, and recommend measures to avoid, minimize, or mitigate potential impacts. This report is based on information available at the time of the biological surveys, site conditions observed, currently available information, and the report preparer's best professional judgment. This report will support the City's California Environmental Quality Act (CEQA) analysis and/or agency consultations.
1.1 Project Setting
The project is on a 2.18-acre property along Pascale Place near Glory Court in Napa, California (APN 045-411-022-000). The project site is accessible from Pascale Road. It is accessible from the east side of Highway 121 from Coombsville Road. It is approximately one mile east of downtown Napa. The property is a former landfill site and remains undeveloped, except for three monitoring wells that are used to track landfill gas. It is situated in a residential area, bordered by residential parcels to the north, east, and south, and Pascale Place to the west. It is mapped on the Napa USGS quadrangle (38.2977°N, 122.2679°W).
The project site is in the Napa Valley, located between the Mayacamas and Vaca Mountains in southern Napa County. The valley stretches from the city of Calistoga in the north to the baylands in the south. The Napa River runs down the valley. It is a 426-square-mile watershed that drains the Napa Valley and flows into San Pablo Bay. The Napa River flows to the east of the property.
Drainage from the site flows through the City’s storm drain system before entering the Napa River.
1 The term “project site” is used to define the project footprint (i.e., remediation site, access routes, and a buffer around). The resources on the larger property are included for context and are important for understanding the biological resource conditions and impact determinations beyond the project footprint.
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Biological Resources Assessment
Hidden Glen Remediation Project, City of Napa
April 2025
Parcel Boundary
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Biological Resources Assessment
Hidden Glen Remediation Project, City of Napa
April 2025
Parcel Boundary
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Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
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1.2 Proposed Project
The City of Napa is proposing to conduct remedial action activities at the former Hidden Glen Dump site. The 2.18-acre City-owned property is located near the intersection of Pascale Place and Glory Court in Napa, CA (APN #045-411-022-000). The site was initially an excavated quarry that operated into the 1940s. After quarry operations were abandoned, a private operator used the site as a general garbage dump until it was abandoned in the 1960s. In 2001, a landfill cap was installed at the dump site. In 2020, three methane monitoring wells were installed to monitor landfill gases (LFG).
The project site contains waste-impacted soil and debris in the shallow soils from its previous operation as the former Hidden Glen Dump and requires remedial action. On November 26, 2019, the County of Napa Environmental Health, Solid Waste Local Enforcement Agency (LEA) issued a letter to the City of Napa requiring the submittal of a work plan to ensure that State Minimum Standards are addressed at the City-owned property in compliance with Title 27 of the California Code of Regulations (CCR). To comply with State Minimum Standards, the letter requires the City to remove and/or cover waste-impacted soil on the site.
A Remedial Action Plan (RAP) was prepared by Ninyo & Moore in October 2024 and approved by the LEA on December 20, 2024. Under the RAP, waste-impacted soil around the perimeter of the landfill cap would be excavated to bedrock, where feasible, to depths of approximately 10 to 20 inches or greater. The depth of excavation will be reduced if bedrock is encountered at shallower depths. Where waste removal is not possible due to access, stability, and/or other restrictions, the remaining waste will be covered with two feet of clean, imported soil to meet state minimum standards. The waste-impacted soil to be removed would be reconsolidated onsite and covered with a minimum of two feet of clean fill, essentially capping it. Alternatively, the waste-impacted soil may be hauled offsite to an appropriate landfill for disposal. The proposed access road would be constructed off a paved private driveway to the lot east of the City-owned property. The access road would be approximately 10 feet wide by 75 feet long. Alternatively, the site may be accessed off Pascale Place. The maximum amount of waste to be removed is approximately 3,500 cubic yards, and clean fill imported into the site is approximately 6,050 cubic yards. Equipment would include large and mini excavators, backhoes, loaders, dump trucks, dozers, and sheep-foot compactors. Excavation would occur within disturbed annual grassland. Several native coast live oak trees may need to be removed to accommodate construction. Construction is anticipated to take place from August to October 2025.
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Hidden Glen Remediation Project
April 2025
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2 Methods
2.1 Background Review
Information on special-status species and habitats was compiled through a review of background literature and databases. The search focused on the known occurrences of special-status species on the Napa 7.5-minute USGS quadrangle where the project is located and the surrounding quadrangles. The following resources were consulted to determine species and habitats within the site:
- The California Natural Diversity Database2 (CNDDB) maintained by the California Department of Fish and Wildlife (CDFW 2025a); RareFind Version 5.3.0, BIOS 6 Version
6.25.0026 (including unprocessed data from CNDDB Online Field Survey Forms), CNDDB GIS Data Version March 31, 2025; this included species reported within a 5-mile buffer around the project,
- CDFW’s Special Animals List, April 2025 (CDFW 2025b), - CDFW’s Special Vascular Plants, Bryophytes, and Lichens List, January 2025 (CDFW 2025c), - CDFW’s California Natural Communities List, February 27, 2025 (CDFW 2025d), - CDFW’s California Sensitive Natural Communities List, February 27, 2025 (CDFW 2025e), - U.S. Fish and Wildlife Service’s Information for Planning and Consultation (IPaC) database (USFWS 2025a),
- California Native Plant Society’s (CNPS) A Manual of California Vegetation Online (CNPS 2025a),
- California Native Plant Society’s Rare Plant Inventory (CNPS 2025b), - Calflora’s Observation Search and Search for Plants databases (Calflora 2025), - USDA Natural Resources Conservation Service Web Soil Survey (WSS; NRCS 2025b), - USDA Soil Survey for Napa County (USDA 1978),
- National Wetlands Inventory (NWI) (USFWS 2025b)
- Google Earth aerial images,
- USGS (2025) topographic maps,
- VegCAMP Vegetation Classification and Mapping Program (CDFW 2016b) and - Historical and current accounts of biological resources within the Napa River watershed and species-specific information are presented in other technical reports, publications, and field guides.
2 The California Natural Diversity Database is an inventory of the status and locations of rare plants and animals in California and is maintained by the California Department of Fish and Wildlife. It is part of an international network of natural heritage programs, managed by NatureServe. It is a positive detection database and only contains records where species have been detected; there are no organized inventory or survey efforts used to populate the database. Observations are submitted by local agencies, researchers, and consultants and reviewed by CDFW staff prior to entry into the database. The CNDDB is not a public dataset; the maps and information provided in this report are for internal review only and should not be used for any public reports or other documents.
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April 2025
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2.2 Biology Field Surveys
Swift Biological completed biological surveys of the project site on March 19, 2025, and April 8, 2025. The field surveys followed the methods described in CDFW’s Protocols for Surveying and Evaluating Impacts to Special-status Native Plant Populations and Natural Communities (CDFW 2009) and Napa County's Guidelines for Preparing Biological Resources Reconnaissance Surveys (Napa County 2016). The surveys were completed to 1) document vegetation communities, 2) compile a list of plant and animal species present, 3) evaluate the project site for the presence of special-status species and their habitats, and 4) evaluate the project site for jurisdictional aquatic features. Areas adjacent to the project site were also observed for context and to evaluate the potential for impacts on off-site resources.
Before the surveys, a background review was completed to generate a list of potentially sensitive biological communities and special-status species that may occur within the project site; see Background Review. A base map of the project site was produced before the field surveys, with the parcel boundaries overlaid on an aerial photograph. The site boundaries and aerial data were also downloaded into the ESRI Field Maps application, and GPS field data on biological features were collected in the field. During the surveys, the entire site and a buffer around it were systematically and thoroughly surveyed to inventory all biological resources present.
Plants. Botanical surveys of the project site were completed to describe the vegetation communities and evaluate for the presence of special-status plants. Surveys were completed in March and April 2025, with an additional survey planned for May 2025 to coincide with the peak blooming periods of special-status plants. Plant communities were identified and described based on the Manual of California Vegetation (CNPS 2025a) definitions. Data downloaded from the VegCAMP Vegetation Classification and Mapping Program for Napa County was used to evaluate vegetation communities within the site (CDFW 2016b). The botanical inventory was floristic in nature, and every plant taxon that occurs on the site was identified to the taxonomic level necessary to determine rarity or listing status. All plants were identified using the Jepson eFlora (Jepson Flora Project 2025) and A Flora of Napa County (Ruygt 2020). Representative plant species observed were incorporated into the Existing Plant Communities section below. A complete list of plants observed is provided in Table 1.
Wildlife. Wildlife surveys of the project site were completed in March and April 2025 to describe the wildlife species and habitats present and evaluate for the presence of special-status species.
Binoculars (Swarovski 10x42) and a high-resolution camera (Canon PowerShot SX70) were used.
All wildlife species were identified by sight or sound, and details of wildlife behavior and activity were recorded. The surveys were carried out under suitable weather conditions to maximize the potential for the detection of wildlife species. The surveys included daytime inspections of all vegetation and an evaluation of unique wildlife habitat features. Representative plant species observed were incorporated into the Wildlife Habitat section below. A complete list of plants observed is provided in Table 2.
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April 2025
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Aquatic Resources. The project site was reviewed for the presence of wetlands, waters of the US and State, and riparian habitat1F
3under the jurisdiction of the US Army Corps of Engineers (Corps), the Regional Water Quality Control Board (RWQCB), and the California Department of Fish and Wildlife (CDFW). Wetland jurisdiction is determined based on a preliminary assessment of hydrophytic vegetation, hydric soils, and hydrology; a site must meet these three parameters to be considered jurisdictional (Corps 1987, 2008b). Waters and other drainage areas are identified based on wetland indicators and other physical characteristics such as a clear, natural line impressed on the bank, shelving, changes in the character of the soil, destruction of terrestrial vegetation, or the presence of litter and debris to indicate the presence of an OHWM (Corps 2008a). Riparian habitat is identified by the riparian vegetation that serves as the demarcation between riparian and upland habitat and/or the top of the stream bank based on topographical changes or other indicators.
2.3 Maps and Photographs
Maps for this report were generated using ESRI ArcGIS ArcMap 10.8.2 software. Field data was collected using the ESRI Field Map application and downloaded in the office to support the mapping efforts. Aerial imagery and existing GIS layers available from ArcGIS Online on soil types, land cover/vegetation, and hydrology were used to create figures that represent conditions on the site. Data downloaded from the VegCAMP Vegetation Classification and Mapping Program for Napa County was also used to characterize the site (CDFW 2016b). Digital photographs were collected in the field to characterize on-site conditions and document biological resources.
3 See Section 6 for definitions.
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3 Existing Conditions
3.1 Physical Characteristics
The project is situated on a 2.18-acre parcel of land. The capped waste disposal area is relatively flat, with an elevation of approximately 126 to 139 feet. The northwest, north, and east sides are near vertical quarry walls. There is an upper terrace above the disposal area to the east with a peak elevation of 176 feet. The site slopes downward to the west along Pascale Place, reaching an elevation of 105 feet along the road. There is a small rocked depression at the western edge of the site and a storm drain along Pascale Place.
According to the USDA’s Natural Resources Conservation Service Soil Survey, the property is underlain by one soil mapping unit: Hambright-Rock outcrop complex, 2 to 30 percent slopes (USDA 1978, NRCS 2025b). It is found on plateaus and uplands. This soil is formed from weathered material from basic rock. It is very stony loam from 0 to 12 inches and bedrock from 12 to 22 inches. The Hambirght-Rock outcrop is moderately well-drained, and the runoff class is medium to rapid. It is not subject to flooding or ponding. This soil is primarily used for wildlife habitat, watersheds, and limited grazing. This soil is not listed as a hydric soil (NRCS 2025a).
3.2 Existing Plant Communities
Plant communities are assemblages of plant species that occur together in the same area, defined by their species composition and relative abundance. According to the 2016 Vegetation Map of Napa County, the parcel is mapped as valley oak woodland (MCV Scientific Name: Quercus lobata) and coast live oak woodland (MCV Scientific Name: Quercus agrifolia - Quercus douglasii; CDFW 2016b). The mapped communities only partially reflect the current conditions. The margins of the capped waste disposal area are dominated by California annual forb/grass vegetation. The edges and hillside above the main disposal area support native oak woodlands dominated by coast live oak (Quercus agrifolia) and blue oak (Q. douglasii).
The main waste disposal area is an open and relatively flat area. It is dominated by non-native annual grasses and forbs and is classified as the Avena spp. – Bromus spp. Herbaceous SemiNatural Alliance (wild oats and annual brome grasslands) based on A Manual of California Vegetation (CNPS 2025a). This alliance can occur in a variety of topographical settings, from foothills, waste places, rangelands, and openings in woodlands (CNPS 2025a), and it is widely distributed in Napa County. The plant composition across the site reflects a history of soil disturbance. Native cover is less than 5% within the non-native annual grassland. Non-native grasses dominate and include wild oat (Avena fatua), ripgut brome (Bromus diandrus), soft chess (B. hordeaceus), perennial rye grass (Festuca perennis), and foxtail barley (Hordeum murinum).
Non-native forbs are abundant, and representative species include wild geranium (Geranium dissectum), smooth cat’s ear (Hypochaeris glabra), burclover (Medicago polymorpha), wild radish (Raphanus sativus), chickweed (Stellaria media), clover (Trifolium sp.), and vetch (Vicia villosa).
Scattered native forbs are also present. These include annual lupine (Lupinus bicolor) and
Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
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fiddleneck (Amsinckia intermedia). Native Miner’s lettuce (Claytonia perfoliata) and bedstraw (Galium aparine) grow along the edges in shadier locations. Small native coyote brush (Baccharis pilularis) have also colonized the center of the disposal area; these plants are approximately a foot in height. The slope above Pascale Road is also dominated by non-native annual grasses and forbs with similar species composition; however, non-native broad-leaf filaree (Erodium botrys), bristly ox-tongue (Helminthotheca echioides), and rose clover (Trifolium hirtum) are more prevalent in this location. Native annual lupine and California poppy (Eschscholzia californica) are also growing on the slope above Pascale Road. Native purple needle grass (Stipa pulchra) is growing in cracks along the edge of the roadside curb. Patches of non-native French broom (Genista monspessulana) are present around the main disposal area, especially at the southwest corner.
The northwest, north, and east sides of the main disposal area are near vertical walls with a rock outcrop to the south, all remnants from the quarry operation. The rock faces are partially vegetated, and there is a stand of intact native woodland on the terrace above the cliffs along the eastern boundary. These areas are characterized as Quercus douglasii Forest and Woodland Alliance (blue oak woodland and forest) based on A Manual of California Vegetation (CNPS 2025a).
The canopy is predominately Q. douglasii in the upland tree canopy, with Q. agrifolia as a codominant. The southwestern corner of the project site also includes a stand of oak trees; at this location, Quercus agrifolia is the only oak species; this area would be characterized as a remnant stand of Quercus agrifolia Forest and Woodland Alliance based on A Manual of California Vegetation (CNPS 2025a). Both of these tree communities are widely distributed in Napa County.
The vertical walls and rock outcrops support stands of native coast live oak, blue oak, gray pine (Pinus sabiniana), California bay (Umbellularia californica), and toyon (Heteromeles arbutifolia).
The understory and lower slopes of the vertical walls support native coyote brush, Miner’s lettuce, sticky monkeyflower (Diplacus aurantiacus), wild cucumber (Marah fabacea), poison oak (Toxicodendron diversilobum), and soap plant (Chlorogalum pomeridianum). The upper terrace woodland is similar in species composition with a canopy dominated by coast live oak, blue oak, and a few gray pines. The understory is dominated by non-native annual grasses and non-native and native forbs, including milkmaids, soap plant, blue dicks (Dipterostemon capitatus), Pacific sanicle (Sanicula crassicaulis), and blue-eyed grass (Sisyrinchium bellum). The rock outcrop to the south supports both coast live oak and blue oak, with toyon and poison oak in the understory. The southwestern corner of the project site supports a small stand of coast live oak with poison oak and annual grasses in the understory.
The property does not contain any wetlands or other natural aquatic habitat features, such as stream channels or drainages. There is a small unvegetated rocked depression at the western edge of the site, but it does not appear to carry water from the site. There is a grated storm drain along Pascale Place to capture street runoff. No evidence of hydrophytic vegetation, hydric soils, and stream or wetland hydrology was observed during biological surveys of the site. All of the plant communities present are dominated by upland grasses, forbs, and woody vegetation.
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Native Trees
Native trees4 and plants on public property in the City of Napa are protected under Chapter 12.44 Public Trees and Plants in the municipal code. Removal or pruning of any protected native tree, significant tree, or tree within the public right-of-way requires a permit from the City of Napa Parks and Recreation Services Department unless it is approved via authorized signature on the development plan; per see Sheet 3 of 5 of the Hidden Glen Dump Remediation Demolition Plan dated October 14, 2024 (Ninyo & Moore 2024). The project will require the removal of several native coast live trees along Pascale Place and/or near the proposed access road. Along Pascale Place, there are two smaller oaks, 3- and 4-inch DBH5 on the lower slope, and a cluster of three trees on the upper slope measuring 15-, 17-, and 20-inch DBH. Near the proposed access road at the southwest corner, there is a multi-trunk coast live oak tree that will need to be removed along with some trimming of larger branches of nearby trees. The remaining trees on the site will be protected in accordance with the Tree Protection Notes and Tree Protection Fencing specifications outlined in the Hidden Glen Dump Remediation Demolition Plan under the guidance of a certified arborist (see Sheet 3 of 5; Ninyo & Moore 2024).
3.3 Wildlife Habitats
Despite its urban location, the project site supports grassland and native oak woodland vegetation and provides habitat for many wildlife species. These areas offer animals nesting habitat, food, shelter, and refuge from the surrounding developed areas. They support a variety of wildlife species that can live and thrive in urban and suburban environments. These species generally have a high tolerance for human disturbance, utilize human food resources, and are typically omnivorous and generalists with regard to food and habitat. The annual grassland is an open habitat with limited shrub and tree cover. This area provides some foraging opportunities for wildlife, especially with the nearby vegetated cover and rock outcrop habitat features. Black-tailed deer (Odocoileus hemionus) were observed foraging in the open grassland. Evidence of fossorial species was observed in the grassland, including small dirt piles and rodent tunnels, despite it being imported topsoil over fill material. Birds in the grassland were limited to house finch (Haemorhous mexicanus) and California towhee (Melozone crissalis). Western fence lizards (Sceloporus occidentalis) were observed on the periphery of the grassland near the rock outcrops.
The woodland areas surrounding the main waste disposal area and open grassland support a diversity of species. These wooded areas support native tree and shrub cover. The coast live oak and blue oak trees are especially valuable to wildlife. These native trees provide food, shelter, and nesting opportunities for a variety of native wildlife, including a number of species that are closely associated with them. Every aspect of the oak tree is utilized as forage, including acorns, leaves, twigs, pollen, roots, and sap. The trees themselves contain nooks, crannies, and perches where wildlife can live, breed, and take shelter. Birds were abundant in the wooded areas. These included 4 Under Chapter 12.45 Trees on Private Property, these include valley oaks (Q. lobata), coast live oak, black oak (Q. kelloggii), California bay, and black walnut (Juglans hindsi) over 12 inches or greater in diameter, blue oak 6 inches or greater in diameter, and coast redwood (Sequoia sempervirens) 36 inches or greater in diameter. 5
DBH = Diameter at Breast Height
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both year-round residents, seasonal migrants, and winter residents based on the field visit timing.
Representative species included California scrub-jay (Aphelocoma californica), oak titmouse (Baeolophus inornatus), ruby-crowned kinglet (Corthylio calendula), Anna’s hummingbird (Calypte anna), Nuttall’s woodpecker (Dryobates nuttallii), dark-eyed junco (Junco hyemalis), bushtit (Psaltriparus minimus), and white-breasted nuthatch (Sitta carolinensis). A great horned owl (Bubo virginianus) was observed roosting in an oak tree on the vertical walls above the main disposal area in both March and April. Whitewash was observed below its roost, along with an opossum carcass. California ground squirrels (Otospermophilus beecheyi) were observed in the wooded areas; burrows were carved into the rock on the vertical faces. Black-tailed deer were observed in the wooded areas as well. Bats could roost in the trees and forage over the site, but no evidence of them was observed during a survey of the trees.
3.4 Wildlife Connectivity
Wildlife movement is essential for their survival. This includes both the day-to-day movements needed for wildlife to acquire food, shelter, and mates, but also for dispersal and migration to ensure gene flow, recolonization of unoccupied habitat, and geographic shifts in response to climate change. Movement is necessary to maintain healthy ecological and evolutionary processes. Habitat linkages are landscape connections that facilitate movement between large, core habitat areas for diverse organisms and processes. These can be critical at both the local and regional levels. Wildlife crossings are structures that allow animals to cross over human-made barriers to allow collections between habitats or allow animals to navigate through areas where they would be prone to vehicle collisions. Barriers can include urban development, roads, fences, and open areas with limited cover. Crossings can range in size from small culverts and underpasses to larger overpasses or green bridges.
The project site is undeveloped, but it is located within a residential community just outside the city. It is bordered by residences to the north, east, and south. Pacscale Place, a paved residential street, forms the western boundary. A cemetery is located across Pascale Place to the west. The adjacent residential properties are separated by fences or partially fenced. Wildlife likely travel through the site; however, the boundary fencing may restrict wildlife movement to a certain degree. The remedial action project will be concentrated in an existing residential neighborhood and outside of any critical wildlife corridor.
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4 Special-status Species and Habitats
4.1 Special-status Species Definition
Special-status Species is a term used primarily in the California regulatory community for species that are considered sufficiently rare and require special consideration and/or protection. They are defined as follows:
Species listed or proposed for listing as threatened or endangered under the Federal Endangered Species Act (ESA) and California Endangered Species Act (CESA); Animals designated by CDFW as Species of Special Concern or Fully Protected; Plants considered by the California Native Plant Society to be rare, threatened, or endangered in California (List 1B, 2, 3, and 4);
Plants listed under the California Native Plant Protection Act (California Fish and Game Code);
Species considered sensitive by other federal agencies (i.e., US Fish and Wildlife Service, US Forest Service, Bureau of Land Management) or State and local agencies or jurisdictions; and
Species that meet the definitions of rare or endangered under the conditions of Section 15380 of the California Environmental Quality Act Guidelines.
4.2 Special-status Species Evaluation Criteria
The potential for each special-status species identified during the background review was evaluated for potential occurrence within the project site. The potential for special-status species to occur on the site is based on the existing site conditions, known distribution and habitat requirements of the species, and the professional expertise of the biologist completing this assessment. The following criteria were used:
No Potential – Suitable habitat is not present, and/or the project site is outside the species’ range.
Not Expected – Habitat is generally unsuitable or of very poor quality, key habitat elements are absent, and/or the project site is isolated from the nearest extant occurrences. The species is not expected to be found within the project site.
Moderate Potential – Marginally suitable habitat or some key habitat elements that could support this species are present within the project site or immediately adjacent to the site.
Species has a moderate potential to occur within the project site.
High Potential – All of the habitat components required by this species are present, and/or the suitable habitat is adjacent to the project site. This species would be expected to be found during focused field surveys. Species has a high potential to occur within the project site.
Present – Species was observed directly or indirectly during surveys and/or known from reported occurrences that are believed to be still extant.
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4.3 Special-status Plants
Based on the background review, a list of special-status plants with the potential to occur within the project site was generated. The background review identified 25 plant species with reported occurrences within the region (Table 3; CDFW 2025a and USFWS 2025a). Table 3 details all specialstatus plant species documented within a 5-mile radius of the project site as well as any of the other special-status species identified in the database review that could potentially occur based on ecological considerations; the table includes their listing status, habitat requirements, and the potential for occurrence within the site.
No special-status plants were observed during the March and April 2025 botanical surveys of the project site. An additional survey is planned for May 2025 to coincide with the peak blooming periods of special-status plants, but none are expected to be found. The proposed remediation work will be completed within the main waste disposal area. This area has a long history of disturbance, first as a former rock quarry and then as a dump site. The surface of the site supports a topsoil layer over geocomposite drainage net and polyethylene membrane, foundation fill, and waste. Native soils and intact native plant communities are absent from the proposed remediation work area. The surrounding vertical walls, rock outcrops, and upper terrace support native bedrock and soil and oak woodland; however, no work will occur there, and no special-status plants have been observed in these locations to date. The proposed remediation work area is highly disturbed, making it unsuitable for special-status plants. This lacks native vegetation communities, hydrological and topographic conditions, and unique soil characteristics necessary to support species-status plants. The project is not likely to impact special-status plants.
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Biological Resources Assessment
Hidden Glen Remediation Project, City of Napa
April 2025
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Figure 3. California Natural Diversity Database Occurrences Sources: Street Map - ESRI, Parcel - City of Napa, CNDDB Occurrences - CDFW
CNDDB version 4/2025; Note: The occurrences shown on this map represent the known locations of the species listed here as of the date of this version. There may be additional occurrences or additional species within this area that have not yet been surveyed and/or mapped. The lack of information in the CNDDB about a species or an area can never be used as proof that no special-status species occur in an area. This map is not intended for public review. It includes sensitive data and is intended for internal planning purposes only.
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4.4 Special-status Animals
Based on the background review, a list of special-status animals with the potential to occur within the project site was generated (Table 4; CDFW 2025a and USFWS 2025a). The background review identified 29 animal species with reported occurrences within the region. Table 4 details all special-status animal species documented within a 5-mile radius of the project site as well as any of the other special-status species identified in the database review that could potentially occur based on ecological considerations; the table includes their listing status, habitat requirements, local observations, and the potential for occurrence within the site.
Two special-status animal species were observed during the biological surveys of the project site and surrounding habitats. These included oak titmouse (Baeolophus inornatus) and Nuttall’s woodpecker (Dryobates nuttallii), both USFWS Birds of Conservation Concern and common birds of oak woodlands and wooded suburban areas in Napa County. The project site, including areas of proposed remediation work, supports habitat features, including native trees and understory vegetation that may support protected nesting birds, including oak titmouse and Nuttall’s woodpecker, and limited roosting habitat for common and special-status bats. Protected nesting birds and bats are described further below. Recommended protection measures are included in the conclusions section.
The remaining special-status animal species identified in the review of background literature were determined to have no or low potential to occur within the project site due to the absence of suitable habitat elements in and immediately adjacent to the site. For these species, the project site lacks the required native vegetation communities, perennial or intermittent streams, ecologically significant wetland habitats, and other wildlife habitat features such as dens, burrows, and other habitat features necessary to support most of the species-status animals identified. The project site is also constrained by the lack of interconnectivity to the documented occupied habitat.
Protected Nesting Birds
There are over 300 bird species that have been documented in Napa County, including 156 that have possible to confirmed breeding status in Napa County (Berner et al. 2003). These include a wide range of species, from habitat generalists to specialists, year-round residents, winter residents, summer residents, spring and fall migrants, and rare vagrants. Bird species of concern are reported in CDFW’s CNDDB, USFWS (2025a), and other bird reporting databases (eBird, iNaturalist). USFWS also identifies migratory and non-migratory Birds of Conservation Concern (beyond those already designated as threatened or endangered) that represent species of high conservation priority that deserve proactive attention (USFWS 2021).
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Native birds are protected under several federal and State regulations, including the Migratory Bird Treaty Act of 1918 (MBTA; 50 CFR 10.13), Bald and Golden Eagle6 Protection Act of 1940 (16 USC 668-668c), Endangered Species Acts, California Fish and Wildlife Code (§3503, 3503.5, and §3513), and California Endangered Species Act. All native nesting birds, with a few exceptions, are protected under these laws. Non-nesting protections extend to golden and bald eagles, CDFW fully protected species, and listed species and their habitats listed under the ESA and CESA.
Under the federal MBTA, “it is unlawful to pursue, hunt, take, capture, kill, possess, sell, purchase, barter, import, export, or transport any migratory bird, or any part, nest, or egg or any such bird unless authorized under a permit issued by the Secretary of the Interior. Take is defined as:
‘pursue, hunt, shoot, wound, kill, trap, capture, or collect, or attempt to pursue, hunt, shoot, wound, kill, trap, capture, or collect”. The Migratory Bird Treaty Reform Act (MBTRA) of 2004 updated the criteria for species to be protected under the MBTA to include “all species native to the United States or its territories, which are those that occur as a result of natural biological or ecological processes.” The MBTA does not protect “nonnative species whose occur in the US are solely the result of intentional or unintentional human-assisted introduction.” Within California, these exceptions include non-native European starling (Sturnus vulgaris), house sparrow (Passer domesticus), rock pigeon (Columba livia), and non-migratory game birds such as California quail, pheasant, and grouse, wild turkey in the families Odontophoridea and Phasianidae. However, nonmigratory game birds are protected under the California Fish and Game Code. Under §3503 of the California Fish and Game Code, “it is unlawful to take, possess, or needlessly destroy the nest or eggs of any bird, except as otherwise provided by this code or any regulation made pursuant thereto.” Under §3513 of the California Fish and Game Code, “it is unlawful to take or possess any migratory nongame bird as designated in the Migratory Bird Treaty Act or any part of such migratory nongame bird except as provided by rules and regulations adopted by the Secretary of the Interior under provisions of the MBTA.”
Construction activities in areas with nesting birds can result in the alteration of the nesting habitat and disruption of nesting activities. Construction activities (including grading, vegetation removal, and worker presence) can result in the destruction of eggs or occupied nests, mortality of young, and the abandonment of nests with eggs or young birds before fledging. If construction-related activities are scheduled during the nesting season, preconstruction nesting bird surveys are required to be completed by a qualified biologist. If nesting birds are found, protection buffers are required, and ongoing monitoring may be necessary. If work is delayed, additional surveys may also be required. Implementation of standard construction Best Management Practices that limit construction activities, including vegetation removal, to the non-nesting season (typically September 1 – January 31) can avoid impacts on native nesting birds. Native birds typical of human-dominated landscapes and suburban woodland and grasslands habitat may occur seasonally or year-round within the project site. Several bird species were observed within the project site, including the oak titmouse and Nuttall’s woodpecker, Birds of Conservation Concern 6 Bald and golden eagles are reported on USFWS IPac list (USFWS 2025a). However, suitable habitat is not present, and these species are not discussed further in this section; see Table 4.
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with USFWS. Native birds may nest within the project site. Nesting birds should be protected per the recommendations provided below.
Common and Special-status Bats
In California, 25 species of bats have been reported, with approximately 15 species reported in the San Francisco Bay area (CDFW 2016a, Zeiner et al 1990). Some species of bats in this region are year-round residents, while others are seasonal. Ten of California’s bat species are listed as Species of Special Concern by CDFW. There are no federally or state-listed bat species occurring within California; therefore, ESA and CESA protections for bats do not apply. There are no laws in California protecting bats as a specific wildlife taxonomic group; however, CEQA requires State and local agencies within California to follow a protocol of analysis and public disclosure of environmental impacts of a proposed project and adopt measures to mitigate those impacts.
CEQA is the single most important law protecting bats, including SSCs and large roosting colonies, within California. The National Forest Service, Bureau of Land Management, and the Western Bat Working Group (WBWG) have identified sensitive bat species and ranked them accordingly. CDFW tracks WBWG priority species; WBWG priority species may be reviewed during CEQA.
Bats forage over a range of habitats and use a variety of features for roosting, including caves, mines, trees, bridges, and buildings. Bat roosts provide security and protection where bats can rest, sleep, hibernate, mate, socialize, and feed. Bats will move between different roost sites throughout the year to support their life cycle requirements. Roosting behavior is speciesdependent. Bats will roost in colonies or as solitary individuals. Bats will also use a range of different features within a roost. Some bats prefer cavities, such as open surfaces; some like crevices, and some use both at different times. A few species will also roost in foliage. Bat roosts are generally defined as the following: 1) hibernation/winter – roosts that are used for extended periods of torpor or hibernation during low temperatures and when food supplies are limited (late fall to early spring), 2) transient - sites used by bats when moving between hibernacula and maternity roosts, often where breeding occurs (spring and fall), 3) day – used by individual bats or small groups of males and non-breeding females to rest or shelter during the day in the breeding season (sunrise to sunset), 4) night– used by individuals or groups of bats to rest and digest food between foraging bouts (sunset to sunrise), and 5) maternity (nursery) – used by females for raising young; these roosts are generally thermally stable, with a low risk of falling and predation of pups (April – August). Bats are particularly vulnerable to disturbance during the maternity season and during winter hibernation. During the maternity season (typically April 15 – September 1), bats are especially vulnerable as females are nursing pups, and the pups are non-volant (not capable of true flight). In the fall, when nighttime temperatures drop below 45oF and the onset of rainfall greater than ½” in 24 hours, bats enter sustained torpor for winter hibernation or maintain a low level of activity; they become more active around March 1 when nighttime temperatures are above 45oF, and rainfall is less than ½” in 24 hours.
Construction activities have the potential to negatively impact bats through direct disturbance to roosting individuals, mortality, and temporary or permanent loss of roosting habitat. The presence
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of construction equipment and personnel can disturb bats through noise and vibrations.
Modifications to roosting habitat can impact a bat's ability to use a roost through changes to entrances, airflow, temperature, and humidity. Modification or removal of suitable roost trees or structures can displace bats. Disruption of bat roosts during the maternity and overwintering periods can impact breeding success, bat fitness, and survivability. Most construction projects are not likely to disrupt the foraging behavior of bats, as bats are mostly nocturnal, and work is generally restricted to daylight hours.
One bat species, the pallid bat (Antrozous pallidus), is reported within a 5-mile buffer of the project (CDFW 2025a; see Table 4). Additional bat species may be present; however, bats are generally underrepresented in the CNDDB. Suitable bat roosting and foraging habitat is present within the project site. Bats could roost in the mature oak trees, especially in the trees with hollows and crevices. The trees proposed for removal were inspected for the presence of bats. This included observing evidence of live or dead bat specimens, bat fecal pellets, urine splashes, and squeaking noises. No evidence of bats was observed. Bats may roost in the mature trees and forage over the site. Construction will occur only during daylight hours and will not interfere with the foraging ability of bats. Construction could require the removal of a number of trees (greater than 12” in DBH with suitable roost sites). Roosting bats should be protected per the recommendations provided below during any tree removal.
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5 Sensitive Natural Communities
Sensitive natural communities are vegetation communities that are considered sensitive by the California Department of Fish and Wildlife based on the range and distribution of a given type of vegetation, the proportion of occurrences that are of good ecological integrity, and threats and trends. Communities are evaluated at both a global (full range within and outside of California) and state (within California) using NatureServe's Heritage Program methodology. Rankings include a single G (global) and S (state) rank ranging from 1 (very rare and threatened) to 5 (demonstrably secure), with those alliances ranked globally (G) or statewide (S) as 1 through 3 considered sensitive. CDFW maintains the California Sensitive Natural Communities list of current vegetation alliances, associations, special stands, and their global and state rarity ranks (CDFW 2025e), as well as the Manual of California Vegetation (Sawyer et al. 2009). It should be noted that some alliances that are not considered sensitive may contain associations that are listed as sensitive by CDFW.
Sensitive natural communities may also be identified in local or regional plans, policies, or regulations. Impacts on sensitive natural communities must be considered and evaluated under the CEQA (CCR Title 14, Div. 6, Chap. 3, Appendix G).
As described under Existing Plant Communities, the main waste disposal area and area of proposed remediation is dominated by non-native annual grasses and forbs and is classified as the Avena spp. – Bromus spp. Herbaceous Semi-Natural Alliance (wild oats and annual brome grasslands; CNPS 2025a). The surrounding vertical walls, rock outcrops, and upper terrace support native woodlands classified as Quercus douglasii Forest and Woodland Alliance (blue oak woodland and forest; CNPS 2025a). The southwestern corner includes several coast live oak trees; at this location, Quercus agrifolia is the only oak species. This area would be characterized as a remnant stand of Quercus agrifolia Forest and Woodland Alliance due to its current size of a few oak trees (CNPS 2025a).
The wild oats and annual broom grasslands are dominated by non-native species and are not considered sensitive. The blue oak woodland and forest association present on the site is Quercus douglasii – Quercus agrifolia; CDFW CA Code 71.020.01. This is ranked G4 S4 and is not considered sensitive (CDFW 2025d). The coast live oak woodland and forest association present on the site is Quercus agrifolia/grass; CDFW CA Code 71.060.09. This is ranked G5 S5 and is not considered sensitive (CDFW 2025d). Based on the current alliances and associations, no sensitive plant communities are present within the project site.
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6 Aquatic Resources
Aquatic resources, including riparian areas, wetlands, and certain aquatic vegetation communities, are considered sensitive biological resources. They fall under the jurisdiction of several regulatory agencies. The US Army Corps of Engineers exerts jurisdiction over “waters of the US.” They regulate the discharge of dredged or fill material into Waters of the US under Section 404 of the Clean Water Act and regulate structures or work in navigable Waters of the US under Section 10 of the Rivers and Harbors Appropriation Act of 1899. The Regional Water Quality Control Board also regulates “waters of the state” under the Porter-Cologne Water Quality Control Act and the federal Clean Water Act. CDFW regulates wetlands and riparian resources associated with rivers, streams, and lakes under the California Fish and Game Code.
Waters of the US include “the territorial seas, and waters which are currently used, or were used in the past, or may be susceptible to use in interstate or foreign commerce, including waters which are subject to the ebb and flow of the tide, tributaries, lakes, and ponds, and impoundments of jurisdictional waters; and adjacent wetlands” (85 FR 22340). Waters of the State include “any surface water or groundwater, including saline waters, within the boundaries of the state” (Water Code Section 13050(e)). This is broadly construed to include all waters within the State’s boundaries, whether private or public, including both natural and artificial channels.
Wetlands include swamps, bogs, seasonal wetlands, seeps, marshes, and other aquatic habitats.
Wetlands are defined as “those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions.” They are typically delineated based on the presence of wetland plants, soils, and hydrology indicators.
Under SB9, wetlands are defined based on the United States Fish and Wildlife Service Manual, Part 660 FW 2, June 21, 1993 (USFWS 1993).
As described under Existing Conditions, the project site contains no wetlands or other natural aquatic habitat features, such as stream channels or drainages. There is a small unvegetated rocked depression at the western edge of the site, but it does not appear to carry water from the site. There is a grated storm drain along Pascale Place to capture street runoff. No evidence of hydrophytic vegetation, hydric soils, and stream or wetland hydrology was observed during biological surveys of the site. All of the plant communities present are dominated by upland grasses, forbs, and woody vegetation.
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7 Conclusions
The City of Napa is proposing to conduct remedial action activities at the former Hidden Glen Dump site. The 2.18-acre City-owned property is located near the intersection of Pascale Place and Glory Court in Napa, CA (APN #045-411-022-000). The site was initially an excavated quarry that operated into the 1940s. After quarry operations were abandoned, the site was used as a general garbage dump by a private operator until it was abandoned in the 1960s. In 2001, a landfill cap was installed at the dump site. During a 2018 site investigation, waste-impacted soils and high lead concentrations were detected, exceeding environmental standards. The City is proposing a remediation project to remove the contaminated soil and cover it with imported clean fill.
Swift Biological Consulting LLC was retained by RCH Group through a contract with the City of Napa to complete a biological resources assessment of the proposed remediation project. This section summarizes the biological resources present on the site based on the background literature, data search, and field surveys and provides conservation measures that should be incorporated into the project. The following discussion is based on a review of the site and the proposed actions outlined in the Remedial Action Plan (Ninjo & Moore 2024) and project documentation provided by the City of Napa.
7.1 Existing Plant Communities
Vegetation communities mapped within the project site include wild oats and annual brome grasslands, blue oak woodland, and remnant coast live oak woodland. The main waste disposal area, and the area of proposed remediation, is an open and relatively flat area. It is dominated by non-native annual grasses and forbs. This area supports primary introduced annual grasses such as wild oat (Avena fatua), ripgut brome (Bromus diandrus), soft chess (B. hordeaceus), perennial rye grass (Festuca perennis), foxtail barley (Hordeum murinum), and other herbaceous non-native species. Native cover is less than 5% within the non-native annual grassland. Surrounding the main disposal area are vertical walls and a rock outcrop to the south, all remnants from the quarry operation. The rock faces are partially vegetated, and there is a stand of intact native woodland on the terrace above the cliffs along the eastern boundary. These areas support stands of native coast live oak (Quercus agrifolia), blue oak (Quercus douglasii), gray pine (Pinus sabiniana), California bay (Umbellularia californica), and toyon (Heteromeles arbutifolia). The understory supports some native shrubs and herbaceous species but is predominately non-native plants. The southwestern corner of the project site supports a small stand of coast live oak with poison oak (Toxicodendron diversilobum) and annual grasses in the understory.
The project will require the removal of several native coast live trees along Pascale Place and/or near the proposed access road off a paved private driveway to the lot east of the City-owned property. Along Pascale Place, there are two smaller oaks (3 to 4 inches in diameter) on the lower slope and a cluster of three larger trees (15 to 20 inches in diameter) on the upper slope. Near the proposed access road at the southwest corner, there is a multi-trunk coast live oak tree that may need to be removed along with some trimming of larger branches of nearby trees. The remaining
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trees on the site will be protected in accordance with the Tree Protection Notes and Tree Protection Fencing specifications outlined in the Hidden Glen Dump Remediation Demolition Plan under the guidance of a certified arborist (see Sheet 3 of 5; Ninyo & Moore 2024).
7.2 Sensitive Natural Communities
Based on the current alliances and associations, no sensitive plant communities are present within the project site. The main waste disposal area and area of proposed remediation is dominated by non-native annual grasses and forbs and is classified as the Avena spp. – Bromus spp. Herbaceous Semi-Natural Alliance (wild oats and annual brome grasslands; CNPS 2025a). This is not a sensitive natural community. The surrounding vertical walls, rock outcrops, and upper terrace support native woodlands classified as Quercus douglasii Forest and Woodland Alliance (blue oak woodland and forest; CNPS 2025a). This is ranked G4 S4 and is not considered sensitive (CDFW 2025d). The southwestern corner includes several coast live oak trees; at this location, Quercus agrifolia is the only oak species. Due to its current size of a few oak trees, this area would be characterized as a remnant stand of Quercus agrifolia Forest and Woodland Alliance (CNPS 2025a). This is ranked G5 S5 and is not considered sensitive (CDFW 2025d).
7.3 Aquatic Resources
The project site does not contain any wetlands or other natural aquatic habitat features, such as stream channels or drainages. There is a small unvegetated rocked depression at the western edge of the site, but it does not appear to carry water from the site. There is a grated storm drain along Pascale Place to capture street runoff. No evidence of hydrophytic vegetation, hydric soils, and stream or wetland hydrology was observed during biological surveys of the site. All of the plant communities present are dominated by upland grasses, forbs, and woody vegetation.
7.4 Special-status Plants
Information on special-status plant species and their habitats was compiled through a review of background literature and databases (Table 3; CDFW 2025a and USFWS 2025a). The background review identified 25 plant species with reported occurrences within the region. Botanical surveys of the project site were completed in March and April 2025. An additional survey is planned for May 2025 to coincide with peak blooming periods for special-status plants. No special-status plants have been observed, and no special-status plant species are expected to be found within the project site. The proposed remediation work will be completed within the main waste disposal area. This area has a long history of disturbance, first as a former rock quarry and then as a dump site. The surface of the site supports a topsoil layer over geocomposite drainage net and polyethylene membrane, foundation fill, and waste. Native soils and intact native plant communities are absent from the proposed remediation work area. The surrounding vertical walls, rock outcrops, and upper terrace support native bedrock and soil and oak woodland; however, no work will occur there, and no special-status plants have been observed in these locations to date.
The proposed remediation work area is highly disturbed, making it unsuitable for special-status
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plants. This area lacks native vegetation communities, hydrological and topographic conditions, and unique soil characteristics necessary to support species-status plants. The project is not likely to impact special-status plants.
7.5 Special-status Animals
Information on special-status wildlife species and their habitats was compiled through a review of background literature and databases (Table 4; CDFW 2025a and USFWS 2025a). The background review identified 29 animal species with reported occurrences within the region. During the wildlife surveys completed in March and April 2025, two special-status animal species were observed. These included oak titmouse (Baeolophus inornatus) and Nuttall’s woodpecker (Dryobates nuttallii), both USFWS Birds of Conservation Concern and common birds of oak woodlands and wooded suburban areas in Napa County. The project site, including areas of proposed remediation work, supports habitat features, including native trees and understory vegetation that may support protected nesting birds, including oak titmouse and Nuttall’s woodpecker, and limited roosting habitat for common and special-status bats. Nesting bird and roosting bat protection measures are outlined below. The remaining special-status animal species identified in the review of background literature were determined to have no or low potential to occur within the project site due to the absence of suitable habitat elements in and immediately adjacent to the site. For these species, the project site lacks the required native vegetation communities, perennial or intermittent streams, ecologically significant wetland habitats, and other wildlife habitat features such as dens, burrows, and other habitat features necessary to support most of the species-status animals identified. The project site is also constrained by the lack of interconnectivity to the documented occupied habitat.
7.6 Nesting Birds
The project site supports breeding habitat for native bird species. Breeding birds are protected under the Migratory Bird Treaty Act, California Fish and Game Code, and federal and state ESAs.
Project activities (including vegetation removal, grading, or other ground-disturbing activities) could result in the alteration of the nesting habitat and disruption of nesting activities.
Construction activities can result in the destruction of eggs or occupied nests, mortality of young, and the abandonment of nests with eggs or young birds before fledging. To avoid potential impacts on native nesting birds, the following protection measures will be implemented:
Preconstruction nesting bird surveys will be completed from February 1- August 31. A survey will be completed within 7 days before the beginning of project-related activities. The survey area will include the project site and an appropriate buffer around the site to identify any nesting that could be impacted directly or indirectly by the project-related activities. The survey will follow established nesting search protocols described in Martin and Geupel (1993) and CDFW and USFWS protocols, where appropriate. If the qualified biologist finds no active nests or breeding activity indicating nests are present, then work can proceed without
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restrictions. If there is a lapse in project-related activities for 7 days or more, then a follow-up survey may be required per the recommendations of the qualified biologist. If active nests are identified during the survey and the nests are within the project site or the buffer area and nesting would be adversely affected, a “No Work Zone” buffer area will be demarcated around each nest site by the qualified biologist. Buffer distances for each bird nest will be site-specific and established to protect the bird’s normal behavior to prevent nesting failure or abandonment. The buffer distance will vary by species, nest location, existing visual and topographical buffers, and intensity and extent of the construction-related disturbance.
The buffer area may be as small as 25-50 feet for common, disturbance-adapted species or much larger (e.g., 100-250 feet) for sensitive species like raptors and owls. The “No Work Zone” will be established in the field with flagging, fencing, or other appropriate material and remain in place until all young in the nest have fledged or the nest otherwise becomes inactive due to predation or other natural causes as determined by the qualified biologist. The qualified biologist will continue to monitor the behavior of the birds at the nest site during construction activities to ensure that they are not disturbed by the project work. Nest monitoring will continue until the nesting attempt is complete. If state and/or federally-listed birds are found breeding within the area, consultation with the CDFW and USFWS may be required. If initial ground-disturbing activities occur outside of the nesting season (September 1 through January 31), then a preconstruction survey would not be required, and construction could begin unimpeded.
7.7 Special-status Bats
The project site supports potential roosting (tree) and foraging habitat for special-status and common bat species. Bats may be present within the trees during construction and forage over the site. Work will be restricted to daylight hours; therefore, no impacts on foraging bats are anticipated. Project construction activities could result in direct impacts on roosting bats if suitable roost trees are removed or significantly trimmed. Indirect impacts can occur as a result of increased human presence and noise during construction. To avoid potential impacts on roosting bats, the following precautionary measures will be implemented:
Before tree removal/trimming (branches over 12” DBH), a qualified biologist will survey for potential bat roosts and occupied habitats. If active bat roosts are identified within the trees to be removed, the disturbance will not be allowed until the roost is abandoned or unoccupied. If tree trimming/removal is postponed or interrupted for more than two weeks from the date of the initial bat survey, the biologist will repeat the pre-construction survey. Tree removal or trimming is recommended from September 1 to October 15 or March 1 to April 15 to avoid the bat maternity roost and winter hibernation season. To the extent feasible, tree work should be avoided between April 15 and September 1 during the maternity roost season [bats are especially vulnerable during this period when females are nursing pups, and the pups are non-volant (not capable of true flight)].
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8 References
Berner, M., B. Grummer, R. Leong, and M. Rippey. 2003. Breeding Birds of Napa County, California.
Napa-Solano Audubon Society, Vallejo, CA.
Calflora. 2025. Calflora database – a non-profit database providing information on wild California plants. http://www.calflora.org/
California Department of Fish and Wildlife (CDFW). 2009. Protocols for Surveying and Evaluating Impacts to Special Status Native Plant Populations and Natural Communities. Sacramento, CA.
California Department of Fish and Wildlife (CDFW). 2016a. Complete List of Amphibian, Reptile, Bird, and Mammal Species in California. May 2016.
California Department of Fish and Wildlife (CDFW). 2016b. VegCAMP Vegetation Classification and Mapping Program. California Department of Fish and Wildlife. Sacramento, CA.
California Department of Fish and Wildlife (CDFW). 2023. Survey Considerations for California Endangered Species Act (CESA) Candidate Bumble Bee Species. June 6, 2023.
California Department of Fish and Wildlife (CDFW). 2025a. California Natural Diversity Database (CNDDB) – Commercial version dated March 2025. RareFind Version 5.3.0, BIOS 6 Version
6.25.0026 (including unprocessed data from CNDDB Online Field Survey Forms), CNDDB GIS Data Version March 1, 2025. Retrieved April 8, 2025. Accessed from:
https://apps.wildlife.ca.gov/rarefind/view/RareFind.aspx https://wildlife.ca.gov/Data/BIOS
https://wildlife.ca.gov/Data/CNDDB/Maps-and-Data#43018408-cnddb-in-bios California Department of Fish and Wildlife (CDFW). 2025b. Special Animals List – April 2025.
California Department of Fish and Wildlife. Sacramento, CA. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=109406&inline California Department of Fish and Wildlife (CDFW). 2025c. Special Vascular Plants, Bryophytes, and Lichens List, April 2025. California Department of Fish and Wildlife. Sacramento, CA. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=109383&inline California Department of Fish and Wildlife (CDFW). 2025d. California Natural Communities List, February 27, 2005. California Department of Fish and Wildlife. Sacramento, CA. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=153398&inline
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California Department of Fish and Wildlife (CDFW). 2025e. California Sensitive Natural Communities List, February 27, 2005. California Department of Fish and Wildlife. Sacramento, CA. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=153609&inline California Native Plant Society (CNPS). 2025a. A Manual of California Vegetation Online. California Native Plant Society. Sacramento, CA. https://vegetation.cnps.org/ California Native Plant Society (CNPS). 2025b. Inventory of Rare Plants. California Native Plant Society. Sacramento, CA. https://www.cnps.org/rare-plants/cnps-inventory-of-rare-plants eBird. 2025. eBird. The Cornell Lab of Ornithology. https://ebird.org/home Jepson Flora Project (eds.) 2025. Jepson eFlora. http://ucjeps.berkeley.edu/eflora/ Martin, T.E. and G.R. Geupel. 1993. Nest-monitoring plots: methods for locating nests and monitoring success. Journal of Field Ornithology 64:507–519.
Napa County. 2016. Attachment B Guidelines for Preparing Biological Resources Reconnaissance Surveys. August 2016.
Natural Resources Conservation Service (NRCS). 2025a. Soil Data Access (SDA) Hydric Soils List. https://www.nrcs.usda.gov/publications/query-by-ssa.html Natural Resources Conservation Service (NRCS). 2025b. Web Soil Survey (WSS). https://websoilsurvey.sc.egove.usda.gov/App?HomePage.htm Ninoyo & Moore. 2024. Remedial Action Plan, Hidden Glen Dump, Coombsville Road, Napa, California, SWIS No. 28-AA-0028. Dated October 16, 2024.
Ruygt, J. 2020. A Flora of Napa County. Published by the California Native Plant Society, Sacramento, CA.
Sawyer, J., T. Keeler-Wolf, and J. Evens. 2009. A Manual of California Vegetation. Second Edition.
California Native Plant Society and California Department of Fish and Game. Sacramento, CA.
Swainson’s Hawk Technical Advisory Committee (SWHA TAC). 2000. Recommended Timing and Methodology for Swainson’s hawk Nesting Surveys in California’s Central Valley. May 31, 2000.
U.S. Army Corps of Engineers (Corps). 1987. Corps of Engineers Wetlands Delineation Manual.
Technical Report Y-87-1. Vicksburg, MS: U.S. Army Corps of Engineers Waterways Experiment Station.
Biological Resources Assessment
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U.S. Army Corps of Engineers (Corps). 2008a. A Field Guide to the Identification of the Ordinary High Water Mark (OHWM) in the Arid West Region of the Western United States. A Delineation Manual. ERDC/CRREL TR-08-12. August 2008. Hanover, NH: U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory.
U.S. Army Corps of Engineers (Corps). 2008b. Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region. Version 2.0. ERDC/EL TR 08-28. September 2008.
Vicksburg, MS: U.S. Army Corps of Engineers Research and Development Center.
U.S. Department of Agriculture (USDA). 1978. Soil Survey of Napa County, California.
U.S. Fish and Wildlife Service (USFWS). 2021. Birds of Conservation Concern 2021. United States Department of the Interior, U.S. Fish and Wildlife Service, Migratory Birds, Falls Church, Virginia. http://www.fws.gov/birds/management/ managed-species/birds-of-conservation-concern.php U.S. Fish and Wildlife Service (USFWS). 2025a. Information for Planning and Conservation (IPaC). https://ecos.fws.gov/ipac/.
U.S. Fish and Wildlife Service (USFWS). 2025b. National Wetlands Inventory – Surface Waters and Wetlands. https://fwsprimary.wim.usgs.gov/wetlands/apps/wetlands-mapper/ U.S. Geological Survey (USGS). 2025. The National Map. https://apps.nationalmap.gov/viewer/ Zeiner, D.C., W.F. Laudenslayer, Jr., K.E. Juneer, and M. White. 1990. California's Wildlife, Volume I-III: Amphibians and Reptiles, Birds, Mammals. California Statewide Wildlife Habitat Relationships System, California Department of Fish and Game, Sacramento, CA.
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9 Photographs
Photographs dated March 19 and April 8, 2025
Looking east (above) and west (below) at the waste disposal site.
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Looking northwest (above) and southwest (below) at the waste disposal site.
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Looking southeast at the waste disposal site (above) and grassland conditions (below).
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Vertical quarry walls adjacent to the disposal site.
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Rocked depression leading to Pascale Place at the western edge of the site (above).
Coast live oak trees proposed for removal near Pascale Place (below).
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Frontage off Pascale Place (above) and looking downslope to Pascale Place from the site (below).
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Existing methane gas monitoring wells.
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Coast live oak tree proposed for removal near the proposed access road and monitoring well (above) and access road area on adjacent property (below).
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Ook woodland on the upper terrace above the waste disposal site.
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10 Tables
Table 1. Plants Species Observed During Botanical Surveys, March – April 2025 Common Name Scientific Name Native or Non-native
American century plant Agave americana non-native
common fiddleneck Amsinckia intermedia native
wild oat Avena fatua non-native
coyote brush Baccharis pilularis native
ripgut brome Bromus diandrus non-native
soft chess brome Bromus hordeaceus non-native
milk maids Cardamine californica native
Italian thistle Carduus pycnocephalus non-native
soap plant Chlorogalum pomeridianum native
bullthistle Cirsium vulgare non-native
miner's lettuce Claytonia perfoliata native
Sticky monkeyflower Diplacus aurantiacus native
blue dicks Dipterostemon capitatus native
broad leaf filaree Erodium botrys non-native
red stemmed filaree Erodium cicutarium non-native
California poppy Eschscholzia californica native
brome fescue Festuca bromoides non-native
annual ryegrass Festuca perennis non-native
fennel Foeniculum vulgare non-native
cleavers Galium aparine native
French broom Genista monspessulana non-native
cut-leaf geranium Geranium dissectum non-native
herb Robert Geranium robertianum non-native
bristly ox-tongue Helminthotheca echioides non-native
toyon Heteromeles arbutifolia native
farmer’s foxtail Hordeum murinum non-native
common barley Hordeum vulgare non-native
smooth cat's ear Hypochaeris glabra non-native
miniature lupine Lupinus bicolor native
wild cucumber Marah fabacea native
burclover Medicago polymorpha non-native
Bermuda buttercup Oxalis pes-caprae non-native
phacelia Phacelia sp. native
gray pine Pinus sabiniana native
coast live oak Quercus agrifolia native
blue oak Quercus douglasii native
Endive daisy Rhagadiolus stellatus non-native
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Common Name Scientific Name Native or Non-native
Pacific sanicle Sanicula crassicaulis native
common groundsel Senecio vulgaris non-native
blue-eyed grass Sisyrinchium bellum native
prickly sowthistle Sonchus asper non-native
common chickweed Stellaria media non-native
purple needle grass Stipa pulchra native
poison oak Toxicodendron diversilobum native
rose clover Trifolium hirtum non-native
clover Trifolium sp. non-native
California bay Umbellularia californica native
vetch Vicia villosa non-native
Table 2. Wildlife Species Observed During Botanical Surveys, March – April 2025 Common Name Scientific Name
California Scrub-Jay Aphelocoma californica
Oak Titmouse* Baeolophus inornatus
Great Horned Owl Bubo virginianus
Red-tailed Hawk Buteo jamaicensis
Red-shouldered Hawk Buteo lineatus
Anna's Hummingbird Calypte anna
Ruby-crowned Kinglet Corthylio calendula
American Crow Corvus brachyrhynchos
Opossum** Didelphis virginiana
Nuttall's Woodpecker* Dryobates nuttallii
House Finch Haemorhous mexicanus
Dark-eyed Junco Junco hyemalis
California Towhee Melozone crissalis
Northern Mockingbird Mimus polyglottos
Black-tailed Deer Odocoileus hemionus
California Ground Squirrel Otospermophilus beecheyi
Bushtit Psaltriparus minimus
Yellow-rumped Warbler Setophaga coronata
Western Fence Lizard Sceloporus occidentalis
White-breasted Nuthatch Sitta carolinensis
European Starling* Sturnus vulgaris
Violet-green Swallow Tachycineta thalassina
Bewick's Wren Thryomanes bewickii
*non-native
**non-native
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Table 3. Special-status Plants Evaluated for Potential to Occur within the Project Site Common
Name Scientific Name Listing Status7
Life Form, Habitat Affinities,
and Blooming Period
Potential for
Occurrence within
the Project Site
Franciscan
onion
Allium peninsulare
var. franciscum 1B.2
Perennial bulbiferous herb.
Cismontane woodland and
valley and foothill grassland;
clay, volcanic, often
serpentinite. Elevation: 170-
1,000 feet. Blooms May-June.
Not expected.
Typical habitat is
not present within
the project site.
Additional survey
planned during the
reported blooming
period.
alkali milkvetch Astragalus tener
var. tener
1B.2
Annual herb. Alkaline playas,
grassland (adobe clay), and
vernal pools. Elevation: 5-195
feet. Blooms March-June.
No potential.
Typical habitat not
present within the
project site.
narrowanthered
brodiaea
Brodiaea
leptandra 1B.2
Perennial bulbiferous herb.
Broadleafed upland forest,
chaparral, cismontane
woodland, lower montane
coniferous forest, and valley
and foothill grassland; volcanic
soils. Elevation: 360-3,000
feet. Blooms May-July.
Not expected.
Typical habitat is
not present within
the project site.
Additional survey
planned during the
reported blooming
period.
Brewer's
caladrinia
Calandrinia
breweri 4.2
Annual herb. Chaparral and
coastal scrub; burned areas,
disturbed areas, sometimes
loam and sandy soils.
Elevation: 35-405 feet. Blooms
March-June
Not expected.
Typical habitat is
not present within
the project site.
Additional survey
planned during the
reported blooming
period.
7 Plant Listing Status Codes
Federal Endangered Species Act (ESA): FE - listed as endangered (in danger of extinction); FT - listed as threatened (likely to become endangered within the foreseeable future); FC - federal candidate species California Endangered Species Act (CESA; State): SE - listed as endangered; ST - listed as threatened; SCE-state candidate to be listed as endangered; SCT-state candidate to be listed as threatened - listed as rare.
California Rare Plant Rank (CRPR): 1A - presumed extirpated in California and either rare or extinct elsewhere; 1B - rare or endangered in California and elsewhere; 2A - presumed extirpated in California, but common elsewhere; 2B - rare or endangered in California, but more common elsewhere; 3 - plants for which we need more information, a review list; 4 – plants of limited distribution, a watch list. The CRPR uses a decimal-style threat rank. The threat rank is an extension added onto the CRPR and designates the level of threats by a 1 to 3 ranking with 1 being the most threatened and 3 being the least threatened (CDFW 2025c).
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Common
Name Scientific Name Listing Status7
Life Form, Habitat Affinities,
and Blooming Period
Potential for
Occurrence within
the Project Site
jonny-nip
Castilleja
ambigua var.
ambigua
4.2 Annual herb (hemiparasitic).
Coastal bluff scrub, coastal
prairie, coastal scrub, marshes
and swamps, valley and
foothill grassland, and vernal
pools (margins). Elevation: 0-
1,425 feet. Blooms MarchAugust.
Not expected.
Typical habitat is
not present within
the project site.
Additional survey
planned during the
reported blooming
period.
holly-leaved
ceanothus
Ceanothus
purpureus
1B.2
Perennial evergreen shrub.
Chaparral and woodland;
rocky, volcanic. Elevation: 395-
2,100 feet. Blooms FebruaryJune.
No potential.
Suitable habitat not
present. No
ceanothus plants
present.
Tracy's clarkia Clarkia gracilis ssp.
tracyi 4.2
Annual herb. Chaparral
(openings, and serpentinite).
Elevation: 215 – 2,135 feet.
Blooms April - July.
No Potential.
Typical habitat and
typical soil
conditions are not
present within the
project site.
dwarf
downingia Downingia pusilla 2B.2
Annual herb. Vernal pools,
often roadside ditches.
Elevation: 5-1,460 feet.
Blooms March-May.
No Potential.
Typical habitat is
not present within
the project site.
small spike
rush Eleocharis parvula 4.3
Perennial herb. Marshes and
swamps. Elevation: 5-9,910
feet. Blooms June-August.
No Potential.
Typical aquatic
habitat is not
present within the
project site.
Greene’s
narrow-leaved
daisy
Erigeron greenei 1B.2
Perennial herb. Chaparral
(serpentinite, volcanic).
Elevation: 260-3,295 feet.
Blooms May-September.
No Potential.
Typical habitat and
microhabitat soil
conditions are not
present within the
project site.
St. Helena
fawn lily
Erythronium
helenae 4.2
Perennial bulbiferous herb.
Chaparral, Cismontane
woodland, lower montane
coniferous forest, and valley
and foothill grassland;
sometimes serpentine and
volcanic soils. Elevation: 1,150-
4,005 feet. Blooms MarchMay.
Not expected.
Typical habitat is
not present within
the project site.
Additional survey
planned during the
reported blooming
period.
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Common
Name Scientific Name Listing Status7
Life Form, Habitat Affinities,
and Blooming Period
Potential for
Occurrence within
the Project Site
San Joaquin
spearscale
Extriplex
joaquinana 1B.2
Annual herb. Chenopod scrub,
meadows and seeps, playas,
and valley and foothill
grassland; alkaline. Elevation:
5-2,740 feet. Blooms AprilOctober.
No Potential.
Typical habitat and
microhabitat soil
conditions are not
present within the
project site.
nodding
harmonia Harmonia nutans 4.3
Annual herb. Chaparral and
cismontane woodland;
volcanic, sometimes gravelly,
rocky soils. Elevation: 245-
3,200 feet. Blooms MarchMay.
No Potential.
Typical habitat and
microhabitat soil
conditions are not
present within the
project site.
Contra Costa
goldfields
Lasthenia
conjugens FE, 1B.1
Annual herb. Cismontane
woodland, alkaline playas,
valley and foothill grassland,
vernal pools (mesic). Elevation:
0-1,540 feet. Blooms MarchJune.
No Potential.
Typical habitat and
microhabitat
conditions are not
present within the
project site.
Delta tule pea Lathyrus jepsonii
var. jepsonii 1B.2
Perennial herb. Marshes and
swamps (freshwater and
brackish). Elevation: 0-15 feet.
Blooms May-July.
No Potential.
Typical aquatic
habitat not present
within the project
site.
legenere Legenere limosa 1B.1
Annual herb. Vernal pools.
Elevation: 5-2,885 feet.
Blooms April-June.
No Potential.
Typical aquatic
habitat is not
present within the
project site.
bristly
leptosiphon
Leptosiphon
acicularis 4.2
Annual herb. Grassland,
woodland, and chaparral.
Elevation: 55-1500 m. Blooms
April-July.
Not expected.
Typical habitat is
not present within
the project site.
Additional survey
planned during the
reported blooming
period.
Jepson’s
leptosiphon
Leptosiphon
jepsonii 1B.2
Annual herb. Chaparral,
cismontane woodland, valley
and foothill grassland; usually
volcanic soils. Elevation: 330-
1,640 feet. Blooms MarchMay.
Not expected.
Typical habitat is
not present within
the project site.
Additional survey
planned during the
reported blooming
period.
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Common
Name Scientific Name Listing Status7
Life Form, Habitat Affinities,
and Blooming Period
Potential for
Occurrence within
the Project Site
Mason's
lilaeopsis Lilaeopsis masonii CR, 1B.1
Perennial rhizomatous herb.
Marshes and swamps
(brackish and freshwater),
riparian scrub. Elevation: 0-35
feet. Blooms April-November.
No Potential.
Typical aquatic
habitat is not
present within the
project site.
Lobb's aquatic
buttercup Ranunculus lobbii 4.2
Annual aquatic herb. Vernal
pools. Elevation: 50-1,540 feet.
Blooms February-May.
No Potential.
Typical aquatic
habitat is not
present within the
project site.
Suisun Marsh
aster
Symphyotrichum
lentum 1B.2
Perennial rhizomatous herb.
Marshes and swamps
(brackish, and freshwater).
Elevation: 0-10 feet. Blooms
May-November
No Potential.
Typical aquatic
habitat not present
within the project
site.
Napa
bluecurls
Trichostema
ruygtii 1B.2
Annual herb. Chaparral,
cismontane woodland, lower
montane coniferous forest,
valley and foothill grassland,
and vernal pools. Elevation:
100-2,230 feet. Blooms JuneOctober.
Not expected.
Typical habitat is
not present within
the project site.
Additional surveys
planned during the
reported blooming
period.
two-fork
clover
Trifolium
amoenum
FE, 1B.1
Annual herb. Coastal bluff
scrub, valley and foothill
grassland (sometimes
serpentinite); moist, heavy
soils, disturbed areas.
Elevation: 15-1,360 feet.
Blooms April-June.
Not expected.
Typical habitat is
not present within
the project site.
Additional surveys
planned during the
reported blooming
period.
saline clover Trifolium
hydrophilum 1B.2
Annual herb. Salt marshes and
swamps, grassland (mesic,
alkaline), vernal pools.
Elevation: 0-985 feet. Blooms
April-June.
No potential.
Typical habitat is
not present within
the project site.
oval-leaved
viburnum
Viburnum
ellipticum 2B.3
Perennial deciduous shrub.
Chaparral, woodland, lower
montane coniferous forest.
Elevation: 705-4,595 feet.
Blooms May-June.
Not expected.
Typical habitat is
not present within
the project site.
Additional survey
planned during the
reported blooming
period.
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Table 4. Special-status Animals Evaluated for Potential to Occur within the Project Site Common Name
Scientific Name Listing Status8 Habitat
Requirements
Local Observations9 and Potential for
Occurrence within the Project Site
Amphibians
California Giant
Salamander
Dicamptodon
ensatus
SSC One of the largest terrestrial salamanders in
North America. Primarily nocturnal. Occurs in
wet coastal forests near permanent and semipermanent streams and seepages. Adults are generally found within 150 feet of aquatic
habitat. Remain underground in retreats and are
more active during the rainy season. Breeding
occurs in spring and sometimes fall.
Reproduction is aquatic. Larvae are streamdwelling and require 18-24 months to transform.
Eat small vertebrates and invertebrates.
No potential. California giant
salamanders are known from
sightings over 5 miles from the
project site. Suitable upland and
perennial stream habitats are not
present within the project site.
Foothill Yellowlegged Frog
Rana boylii pop.1
North Coast DPS
SSC Found in small tributary streams with perennial
water. Breeding and rearing streams are
generally sunlit with microhabitat features (e.g.,
boulders) and low flow velocities. Typically found
within close proximity to the stream channel,
small upland movements have been noted. Nonbreeding habitat also includes adjacent terrestrial riparian habitat and nearby features
that provide high-flow refuge. Breeding occurs in
spring after winter runoff has subsided (typically
May-June). Eggs attached to rock and vegetative
substrates in shallow, slow-moving water. Mostly
active during daylight. Adults consume a variety
of aquatic invertebrates. Tadpoles graze algae
and detritus.
No potential. Foothill yellow-legged
frogs are known from both extirpated
and extant sightings in the Napa River
watershed over 5 miles from the
project site. Suitable aquatic habitat
is not present within the project site.
California Redlegged Frog
Rana draytonii
FT, SSC Largest native frog in the western US. Breed in a variety of aquatic habitats with still to slowmoving water and emergent vegetation must hold water into late summer or early fall. Found
in streams, ponds, marshes, sag ponds, dune
ponds, and lagoons, including both natural and
manmade features. Non-breeding habitat
includes areas used for breeding and other nonbreeding habitats such as springs, vegetated seeps, riparian habitat, and oftentimes other less
conspicuous upland locations like burrows and
leaf litter. Breeding occurs between November
and April (egg-laying is generally January –
February). Eggs are deposited in a large
grapefruit-sized mass on emergent vegetation
just below the water's surface. Variable diet.
No potential. There are no reported
occurrences of this species within 5
miles of the project site. Species
reported on USFWS IPac list. Suitable
habitat is not present within the
project site.
8 Animal Listing Status Codes
Federal: FE-federally listed as endangered, FT-federally listed as threatened, FC-federal candidate species, BCC-USFWS Bird of Conservation Concern
State: SE-state listed as endangered, ST-state listed as threatened, SC (Endangered)-state candidate to be listed as endangered under CESA, Candidate SE-state candidate to be listed as endangered under CESA, SC (Threatened)-state candidate to be listed as threatened under CESA, FPCDFW fully protected, SSC-CDFW Species of Special Concern, and WL-CDFW Watch List (CDFW 2025b). 9 Occurrence information based on CDFW’s California Natural Diversity Database (CDFW 2025a).
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Common Name
Scientific Name Listing Status8 Habitat
Requirements
Local Observations9 and Potential for
Occurrence within the Project Site
Western
Spadefoot
Spea hammondii
FC
(Threatened),
SSC
A small 1 ½ to 2 ½-inch toad of mixed
woodlands, grasslands, coastal sage scrub,
chaparral, sandy washes, lowlands, river
floodplains, alluvial fans, playas, alkali flats,
foothills, and mountains. Requires open areas
with sandy or gravelly soils spends most of its life
buried underground in earth-filled burrows. The
species is completely terrestrial, only entering
the water to breed. Breeds from January through
May, peaking in February and March, 1-2 days
after heavy rains. Breeding occurs in temporary
pools or quiet streams without bullfrogs, fish,
and crayfish. Eggs hatch after 3 to 4 days on
average. Tadpoles transform in 4 to 11 weeks.
Both juveniles and adults are nocturnal.
No potential. There are no reported
occurrences of this species within 5
miles of the project site. Species
reported on USFWS IPac list. Suitable
aquatic and upland habitat is not
present within the project site.
Reptiles
Western Pond
Turtle
Emys marmorata
FC
(Threatened),
SSC
Only native turtle in Napa County. Found in
ponds, lakes, rivers, streams, creeks, marshes,
irrigation ditches, and upland areas. Nest dug in
upland areas along stream or pond margins in
sunny, grassy areas. Mating occurs from April to
May (8-10 years old). 2-11 eggs laid. Hatchlings
emerge in late summer-fall and sometimes
overwinter in the ground. Active FebruaryMarch. Diurnal and aquatic. Requires basking sites – logs, banks, etc. Eat plants, invertebrates,
carrion, and occasionally frogs and fish.
No potential. Western pond turtle is
known from multiple sightings within
a 5-mile radius of the project site,
including the mainstem Napa River,
Tulucay Creek (0.8 miles, the nearest
sighting), and other water bodies. The
project site is isolated from known
populations by heavily traveled
roadways and development. Suitable
habitat is not present within the
project site.
Birds
Golden Eagle
Aquila chrysaetos
FP, WL
(nesting and
wintering)
The golden eagle is the most widely distributed
bird in the Northern Hemisphere and one of the
largest birds in North America. It occurs in open
country, especially around mountains, hills, and
cliffs. It is primarily solitary and feeds on
mammals. It nests in large trees or on cliffs. The
nest is a bulky platform of sticks lined with
weeds, grass, leaves, and moss. It breeds from
late January through August. Birds may mate for
life. It is a year-round resident of Napa County,
where it occupies mountain and ranch areas in
the eastern portion of the county (Napa).
No potential. Golden eagles are
known from mountainous and ranch
country in eastern Napa County.
There are historic and unprocessed
records of this species in the CNDDB.
They are also reported in the Berner
et al. 2003. Suitable habitat is not
present within the project site.
Oak Titmouse
Baeolophus
inornatus
BCC Small, brown-tinged gray bird with small crest.
Occurs in oak woodlands and open pine or mixed
oak-pine forests. Their call resonates through
woodland habitats, a harsh, fussy see-dee-dee or
chick-a-dee-dee. Feeds among the branches and
larger twigs of trees for insects among the
foliage and bark. Feeds primarily on insects, nuts,
and seeds. Pairs mate for life and defend
Present. Species observed within the
project site. Suitable foraging and
nesting habitat is present in the oak
trees on the site. See breeding bird
protection measures.
Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
Page | 45
Common Name
Scientific Name Listing Status8 Habitat
Requirements
Local Observations9 and Potential for
Occurrence within the Project Site
territories year-round. Nest in cavities of trees or
nest boxes. A year-round resident in Sonoma
County.
Swainson’s Hawk
Buteo swainsoni
ST A large buteo with slender and long wings and a
short tail. Coloration is variable but typically
uniform dark upper side, dark chest, and dark
gray flight feathers. They are uncommon in
prairies and farmlands. Nesting occurs in isolated
trees. They are usually solitary but migrate in
larger flocks. They feed on small mammals and
reptiles in summer and invertebrates during the
rest of the year. Breeding is concentrated in the
Central Valley and in the Great Basin area of
northeastern California.
Not expected. Swainson’s hawks have
been reported within 5 miles of the
project site. They are known to breed
in the lower Napa River watershed in
the vicinity of Suscol Creek, Napa
Valley Business Park, County Airport,
and nearby areas. The nearest
confirmed nesting site is 3 miles from
the project site. The project site
features disturbed grasslands (less
than 2 acres) with trees along the
periphery. Residential parcels
surround the project site. The site is
not likely to support a breeding pair
with suitable forage and protection
from nearby residential disturbances.
The site was visited on two occasions
during the Swainson’s hawk breeding
season: Period II, during nest territory
establishment, and Period III, during
the active nesting period (SWHA TAC
2000). No raptors were observed.
Due to its residential location and
limited habitat, Swainson’s hawk are
not likely to be present within the
project site.
Ferruginous Hawk
Buteo regalis
WL The ferruginous hawk is the largest hawk in
North America. It occurs in North America, from
southwestern Canada through the western
United States and into northern Mexico, and
occupies prairies, deserts, and open-range land.
It is a predator of open country. It forages for
ground squirrels, rabbits, hares, mice, and
pocket gophers while soaring or hunting from
low perch or ground. It is one of the most
adaptable nesting raptors and will use various
features, including trees, ledges, nest platforms,
power poles, and other manmade structures. A
pair will build or refurbish their stick nest, which
may be re-used year after year. Winters in Napa
County, no documented occurrences of
breeding.
No potential. Ferruginous hawks were
reported in the Napa Valley Business
Park area in 1989 when the area
supported open grasslands before
development. This species is known
to overwinter in Napa County, but
there are no reported breeding
occurrences (Berner et al. 2003).
Suitable habitat is not present within
the project site.
Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
Page | 46
Common Name
Scientific Name Listing Status8 Habitat
Requirements
Local Observations9 and Potential for
Occurrence within the Project Site
Nuttall's
Woodpecker
Dryobates nuttallii
BCC Small woodpecker of oak woodland habitats.
Feeds primarily on insect larvae by tapping and
probing into the crevices of oak trees. This
species is found year-round in oak woodlands,
wooded suburban areas, and near streams. This
species is non-migratory. It occurs throughout
California’s oak woodland communities but
extends into Baja, Mexico. A cavity nesting
species. Males excavate out a cavity in a dead
tree. They form monogamous pairs and will
defend their territories year-round. A permanent
resident in Napa County oak woodlands.
Present. Species observed within the
project site. Suitable foraging and
nesting habitat is present in the oak
trees on the site. See breeding bird
protection measures.
White-tailed Kite
Elanus leucurus
FP A small hawk with a white body and black
wingtips and shoulders. They are common in
savannas, open woodlands, marshes, desert
grasslands, partially cleared lands, cultivated
fields, and even highway median strips. Hovers in
flight and parachutes down on their prey. Feeds
primarily on small mammals. Breeding occurs
from February to October, with a peak in May to
August. Nests are typically constructed in large
bushes or trees, open in an isolated stand.
During the non-breeding season, may roost
communally. Fairly common permanent resident
in Napa County.
Not expected. White-tailed kites are
known to occur year-round in the
valley and grasslands habitat of Napa
County. This species is reported
within 5-mile radius of the project
site. If present nearby, kites could
occasionally forage within the project
site. Due to its residential location
and limited habitat, there is low
potential for white-tailed kites to
breed within the project site.
However, all nesting birds will be
protected per the recommendations
provided in this report.
American
Peregrine Falcon
Falco peregrinus
anatum
Delisted The peregrine falcon is the most widely
distributed bird of prey, with 16 recognized
subspecies. It is the world's fastest bird, with
diving speeds of 186 mph, and feeds primarily on
birds. It forages in woodlands, wetlands, forests,
and coastal habitats, as well as agricultural areas
and cities. Nests are typically constructed on cliff
ledges, snags or old nests of other birds, and
manmade structures. No nest is built; eggs are
laid in a simple scrape. Birds may mate for life.
No potential. Peregrine falcons are
known from mountainous and open
spaces areas in Napa County. There
is one reported occurrence of this
species within a 5-mile radius of the
project site. Suitable habitat is not
present within the project site.
Saltmarsh
Common
Yellowthroat
Geothlypis trichas
sinuosa
BCC, SSC The San Francisco or saltmarsh common
yellowthroat is one of 13 recognized subspecies.
It is endemic to the greater San Francisco Bay
region, where it occupies wetlands with adjacent
riparian thickets. This species is insectivorous
and forages for insects and spiders. It constructs
an open cup nest that is well-concealed near the
ground in grasses and herbaceous vegetation.
Breeding occurs from mid-March to late July and
occurs year-round within its breeding range.
No potential. Saltmarsh common
yellowthroats are reported in the
tidal areas along the lower Napa
River. Suitable wetland and riparian
habitat are not present within the
project site.
Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
Page | 47
Common Name
Scientific Name Listing Status8 Habitat
Requirements
Local Observations9 and Potential for
Occurrence within the Project Site
Black-crowned
Night Heron
Nycticorax
nycticorax
None A medium-sized heron with a black crown and
back. Common in wetlands, including
saltmarshes, freshwater marshes, swamps,
streams, rivers, lakes, ponds, lagoons, tidal
mudflats, canals, reservoirs, and wet agricultural
fields. An opportunistic feeder that consumes a
variety of terrestrial, freshwater, and marine
animals. Typically nests in colonies with other
herons. Nests are constructed in trees or in
cattails and consist of a platform made of sticks,
twigs, and other vegetation. Females lay 3-5
eggs. Nests and behaves socially all year.
No potential. Black-crowned night
herons are known to forage in
suitable wetland habitats within a 5-
mile radius of the project site (eBird
2025). There is an old rookery site
within 5 miles. No rookeries are
present within the project site, and
limited rookery habitat is present.
Suitable foraging and nesting habitat
is not present within the project site.
Bank Swallow
Riparia riparia
ST Smallest swallow in North America. Found
primarily in riparian and other lowland habitats.
Forages by hawking insects during long, gliding
flights. Breeding season occurs from early May
through July. A colonial nesting species. Nests on
earthen banks and bluffs. Generally, dig their
own nesting burrows, sometimes up to five feet
long. A long-distance migrant, wintering in the
lowlands of South America. There is one historic
record of bank swallows nesting in Napa County
from the 1930s (Berner et al. 2003).
No potential. There are no reported
occurrences of this species within 5
miles of the project site. Suitable
habitat is not present within the
project site.
California Least
Tern
Sternula antillarum
browni
FE, SE, FP Small, migratory shorebird and one of three
recognized subspecies. Winter in Central
America, the Caribbean, and northern South
America. During the breeding season, occur
along the Pacific coast from San Pablo Bay to San
Jose del Cabo in Baja, California. Known from 23
nest sites, some of which are natural, and others
are man-made, including beaches close to river
mouths, estuaries, and coastal embayment’s.
Breeding occurs from mid-April to midSeptember. Nesting colonies consist of 15 to 300 pairs. Forage in nearshore waters, estuaries, and
river mouths for small, slender fish.
No potential. There are no reported
occurrences of this species within 5
miles of the project site. Species
reported on USFWS IPac list. Suitable
habitat is not present within the
project site.
Northern Spotted
Owl
Strix occidentalis
caurina
FT, ST Occupies old-growth forests in the northern
range and mixed old-growth and younger forest
types in the southern range. Consumes primarily
small mammals, other birds, and insects. It
requires a large territory size for nesting and
foraging. Nests in cavities or platforms in large
trees. Breeding season occurs from early March
through September. Permanent year-round
resident in Sonoma County in old-growth and
mixed forest habitats. Spotted owls have
experienced a population decline due to the loss
and degradation of existing mature and oldgrowth forests and, most recently, the establishment of barred owls in the west.
No potential. Spotted owls are known
to occur in forested locations to the
northwest, but not within a 5-mile
radius of the project site. Suitable
forested habitat is not present within
the project site.
Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
Page | 48
Common Name
Scientific Name Listing Status8 Habitat
Requirements
Local Observations9 and Potential for
Occurrence within the Project Site
Fish
Steelhead - Central
California Coast
DPS
Oncorhynchus
mykiss
FT, SSC Steelhead transition from freshwater, tidal
zones, to the ocean during different life stages.
Steelhead immigrate during high flow events and
sand bar breaches between December and April
and spawn shortly after reaching their spawning
grounds. Juvenile freshwater residence can
range from one to three years depending on
environmental conditions and growth rates.
Adults typically spend one to two years in the
ocean before returning to their natal streams to
spawn. Steelhead may spawn more than one
season before dying; however, the majority of
adults only spawn one time.
No potential. Steelhead are known
from the San Francisco Bay Estuary
and the Napa River. Suitable aquatic
habitat is not present within the
project site.
Longfin Smelt
Spirinchus
thaleichthys
FE, ST Small fish found along the Pacific coast from
Alaska to California Estuary. In California they
use a variety of habitats from nearshore waters,
to estuaries and lower portions of freshwater
streams. A slender-bodied fish, reaching 90-124
mm. A pelagic (lives in the open water column
away from the bottom) and euryhaline species
(tolerant of a wide salinity range). They consume
primarily opossum shrimp but eat copepods and
other small crustaceans. Spawning occurs from
November through May, with a peak in February
through April. Longfin smelt is semelparous,
living two, sometimes three years, and dying
after spawning.
No potential. Longfin smelt are
known from the San Francisco Bay
Estuary. Suitable aquatic habitat is
not present within the project site.
Invertebrates
Western Bumble
Bee
Bombus
occidentalis
SC
(Endangered)
The western bumble bee has a broad range
extending from Canada to northern Mexico.
Historically, it occurred in a range of habitats
within California (shrublands, chaparral, gardens,
and urban parks) from sea level to high
elevations. It is currently restricted to coastal
grasslands in northern California and highelevation meadows, forests, and riparian areas in the Sierra Nevada and Cascade Range. It lives in
small, highly social, and interdependent colonies.
They are a generalist forager.
No potential. The western bumble
bee is known from a 1962 collection
in the Vallejo hills. This species is not
known to currently occur within Napa
County (CDFW 2023). Given the lack
of Napa County sightings and historic
land disturbances, suitable habitat is
not present within the project site.
Conservancy Fairy
Shrimp
Branchinecta
conservatio
FE A small freshwater crustacean measuring 0.6 to
1.1 inches. It occurs in large, turbid freshwater
vernal pool habitats. It is found only in
California’s Central Valley. They are opportunistic
filter feeders. The average life span is 114 days.
Eggs (cysts) sink to the bottom of a pool and
remain viable for several years. They can
withstand extreme environmental conditions
and even digestion by predators due to their
protective coating. There are 10 known
populations in the Central Valley. Named after
No potential. There are no reported
occurrences of this species within 5
miles of the project site. Species
reported on USFWS IPac list. Suitable
aquatic habitat is not present within
the project site.
Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
Page | 49
Common Name
Scientific Name Listing Status8 Habitat
Requirements
Local Observations9 and Potential for
Occurrence within the Project Site
The Nature Conservancy, which protected
several pools where this species occurs.
An Isopod
Calasellus
californicus
None A freshwater isopod. Reaches up to 6.2
millimeters in length. Three collections in
California from a freshwater well and two springs.
Known from Lake, Napa, Marin, Santa Cruz, and
Santa Clara Counties. There is no published
information on the life history or behavior of this
species.
No potential. This species was
collected from a spring in 1969 near
the town of Napa. Suitable habitat is
not present.
Monarch ButterflyCalifornia
Overwintering
Population
Danaus plexippus
plexippus pop.1
FC
(Threatened)
Large, brightly colored butterfly. Two
populations are separated by the Rocky
Mountains. Populations along the California
coast overwinter within 1.5 miles of the
coastline. Overwintering sites are typically
dominated by eucalyptus but are also found on
Monterey pine, Monterey cypress, western
sycamore, coast redwood, and coast live oak.
Requires good solar radiation exposure and wind
shelter. Arrives at overwintering grounds in
September-October and disperses by FebruaryMarch. Migrates to inland locations during the breeding season. Requires native narrow-leaf
milkweed (Asclepias fascicularis) or showy
milkweed (A. speciosa) for egg deposition. Larvae
develop on milkweed plants.
Not expected. Monarch butterflies
are known to overwinter in the
coastal regions. Suitable
overwintering habitat is not present
on the project site. Monarchs can
breed in inland locations, but suitable
larval host plants are not present.
Monarchs may occur in the region on
a limited basis as a seasonal migrant.
Plants on the project site provide
limited adult nectar sources.
Monarchs would not be expected to
occur on the project site at any
frequency.
Valley Elderberry
Longhorn Beetle
Desmocerus
californicus
dimorphus
FT A medium-sized, red and dark green insect with
long antennae. Males range in size from ½ to 1
inch, and females from ¾ to 1 inch. Endemic to
riparian habitats in the Central Valley of
California. Found in association with its host
plant, elderberry (Sambucus spp.). Female lays
her eggs on the bark of the elderberry plant,
with larvae burrowing into the stems after
hatching. Larval stage can last up to two years.
Larvae emerge in March and June. Adults most
active in spring and early summer.
No potential. There are no reported
occurrences of this species within a 5-
mile radius of the project site. Species
reported on nearby quadrangles.
Suitable habitat, including elderberry
host plants, is not present within the
project site.
Western Ridged
Mussel
Gonidea angulata
None Freshwater mussel found in streams and,
oftentimes lakes, with constant water flow and
well-oxygenated substrates. Reach up to 5 inches
in length. A filter feeder that siphons suspended
particles from the water column. Consume
plankton, bacteria, dissolved organic material,
and algae. Limited mobility. Mature at
approximately 7 years and expected to live up to
30 years. Occurs in California, Oregon,
Washington, Idaho, Nevada, and British
Colombia.
No potential. This species was
collected at an unknown date near
the town of Napa. Suitable aquatic
habitat is not present.
Biological Resources Assessment
Hidden Glen Remediation Project
April 2025
Page | 50
Common Name
Scientific Name Listing Status8 Habitat
Requirements
Local Observations9 and Potential for
Occurrence within the Project Site
California
Freshwater Shrimp
Syncaris pacifica
FE, SE Endemic to Marin, Sonoma, and Napa Counties.
Occur in low elevation (less than 380 feet), low
gradient streams (less than 1%) with perennial
flow, or intermittent streams with perennial
pools. Streams are generally structurally diverse
with undercut banks, overhanging woody debris
and vegetation, and exposed roots.
Reproduction occurs once a year in the fall.
Females retain eggs through the winter and
remain attached to the abdominal swimming
legs until May or early July. Forage on fine
particulate organic matter, but have been
observed feeding on dead fish as well.
No potential. California freshwater
shrimp are known from the Napa
River and tributaries. Suitable aquatic
habitat is not present within the
project site.
Mammals
Pallid Bat
Antrozous pallidus
SSC Grassland, shrubland, forest, and woodland
habitats from sea level up through mixed
coniferous forests. Found from south-central
British Colombia to central Mexico and Cuba.
Most common in open, dry habitats with rocky
areas for roosting. A social species forming small
colonies. Roosting sites include caves, mines,
crevices, buildings, and hollow trees during the
day, and more open sites are used at night. Feed
on a variety of insects and arachnids; most prey
are taken on the ground. The mating season
ranges from October to February. One to three
(typically twins) pups are born from April to July.
A yearlong resident throughout most of its
range.
Moderate potential. The pallid bat is
reported from multiple sightings
within 5 miles of the project site. Bats
may forage over the project site.
Some of the larger trees may provide
limited roosting habtiat. See bat
protection measures.
Salt Marsh Harvest
Mouse
Reithrodontomys
raviventris
FE, SE, FP Endemic to the San Francisco Bay Estuary.
Occupies salt and brackish marshes and adjacent
uplands. Prefers habitat dominated by
pickleweed, alkali bulrush, and fat hen.
Pickleweed is their primary food source.
Breeding occurs from spring through autumn
with up to two litters per year. Nests are
constructed in wetland habitats with dense
cover. Can live up to 18 months or possibly
longer. Two subspecies are recognized, northern
and southern, based on range and morphological
characters.
No potential. Salt marsh harvest mice
are reported in the tidal areas along
the lower Napa River. Suitable marsh
habitat is not present within the
project site.
American Badger
Taxidea taxus
SSC Common in open grassland habitats may also
occur in forest meadows, marshes, and brushy
areas, with friable soils for digging for prey. They
are fossorial carnivores. Prey includes pocket
gophers, ground squirrels, moles, mice, and
voles in this region. They will also eat snakes,
birds, and other wildlife. They are typically
nocturnal and do not hibernate, but become less
active in winter. Mating occurs in late summer
and early fall. Young are born from late March to
early April. They dig their own burrows or
enlarge other animal burrows.
No potential. The American badger is
known from 1911 and 1937
collections within 5 miles of the
project site. Evidence of American
badgers was not observed during
repeat surveys of the site. Given the
lack of recent confirmed sightings
within the general vicinity of the site,
existing soil conditions, and urban
setting, suitable habitat is not present
within the project site.
APPENDIX E
MITIGATION MONITORING AND REPORTING PROGRAM
(MMRP)
MITIGATION MONITORING AND REPORTING PROGRAM
Napa Hidden Glen Remediation Project RCH Group
Draft Initial Study/Mitigated Negative Declaration 1 July 2025 MITIGATION MONITORING AND REPORTING PROGRAM – NAPA HIDDEN GLEN REMEDIATION PROJECT Mitigation Measure Monitoring Agency Implementation Schedule Sign-off
AIR QUALITY
Mitigation Measure AQ-1: The applicant shall implement the following during construction of the Project:
• All exposed surfaces (e.g., parking areas, staging areas, soil piles, graded areas, and unpaved access roads) shall be watered two times per day.
• All haul trucks transporting soil, sand, or other loose material off site shall be covered. • All visible mud or dirt track-out onto adjacent public roads shall be removed using wet power vacuum street sweepers at least once per day. The use of dry power sweeping is prohibited. • All vehicle speeds on unpaved roads shall be limited to 15 miles per hour. • All roadways, driveways, and sidewalks to be paved shall be completed as soon as possible.
Building pads shall be laid as soon as possible after grading unless seeding or soil binders are used. • All excavation, grading, and/or demolition activities shall be suspended when average wind speeds exceed 20 mph.
• All trucks and equipment, including their tires, shall be washed off prior to leaving the site. • Unpaved roads providing access to sites located 100 feet or further from a paved road shall be treated with a 6- to 12-inch layer of compacted wood chips, mulch, or gravel. • A publicly visible sign shall be posted with the telephone number and the person to contact the City regarding dust complaints. This person shall respond and take corrective action within 48 hours. The BAAQMD’s phone number shall also be visible to ensure compliance with applicable regulations.
City of Napa Utilities
Department
During construction activities
BIOLOGICAL RESOURCES
Mitigation Measure BIO-1: To avoid potential impacts on nesting birds, the following protection measures shall be implemented:
• Preconstruction nesting bird surveys shall be completed from February 1- August 31. A survey shall be completed within 7 days before the beginning of Project-related activities. The survey area shall include the Project site and an appropriate buffer around the site to identify any nesting that could be impacted directly or indirectly by the Project-related activities. The survey shall follow established nesting search protocols described in Martin and Geupel (1993) and CDFW and USFWS protocols, where appropriate. If the qualified biologist finds no active nests or breeding activity indicating nests are present, then work can proceed without restrictions. If there is a lapse in Project-related activities for 7 days or more, then a follow-up survey may be required per the recommendations of the qualified biologist.
• If active nests are identified during the survey and the nests are within the Project site or the buffer area and nesting would be adversely affected, a “No Work Zone” buffer area shall be demarcated City of Napa Utilities
Department
Prior to construction activities
I I
I I
MITIGATION MONITORING AND REPORTING PROGRAM
Napa Hidden Glen Remediation Project RCH Group
Draft Initial Study/Mitigated Negative Declaration 2 July 2025 MITIGATION MONITORING AND REPORTING PROGRAM – NAPA HIDDEN GLEN REMEDIATION PROJECT Mitigation Measure Monitoring Agency Implementation Schedule Sign-off around each nest site by the qualified biologist. Buffer distances for each bird nest shall be sitespecific and established to protect the bird’s normal behavior to prevent nesting failure or abandonment. The buffer distance shall vary by species, nest location, existing visual and topographical buffers, and intensity and extent of the construction-related disturbance. The buffer area may be as small as 25-50 feet for common, disturbance-adapted species or much larger (e.g., 100-250 feet) for sensitive species like raptors and owls. The “No Work Zone” shall be established in the field with flagging, fencing, or other appropriate material and shall remain in place until all young in the nest have fledged or the nest otherwise becomes inactive due to predation or other natural causes as determined by the qualified biologist. The qualified biologist shall continue to monitor the behavior of the birds at the nest site during construction activities to ensure that they are not disturbed by the project work. Nest monitoring shall continue until the nesting attempt is complete. If state and/or federally-listed birds are found breeding within the area, consultation with the CDFW and USFWS may be required.
• If initial ground-disturbing activities occur outside of the nesting season (September 1 through January 31), then a preconstruction survey would not be required, and construction could begin unimpeded.
Mitigation Measure BIO-2: To avoid potential impacts on roosting bats, the following protection measures shall be implemented:
• Before tree removal/trimming (branches over 12” Diameter at Breast Height [DBH]), a qualified biologist shall survey for potential bat roosts and occupied habitats. If active bat roosts are identified within the trees to be removed, the disturbance shall not be allowed until the roost is abandoned or unoccupied.
• If tree trimming/removal is postponed or interrupted for more than two weeks from the date of the initial bat survey, the biologist shall repeat the pre-construction survey. • Tree removal or trimming is recommended from September 1 to October 15 or March 1 to April 15 to avoid the bat maternity roost and winter hibernation season. • To the extent feasible, tree work should be avoided between April 15 and September 1 during the maternity roost season [bats are especially vulnerable during this period when females are nursing pups, and the pups are non-volant (not capable of true flight)].
City of Napa Utilities
Department
Prior to tree removal and
trimming activities
Mitigation Measure BIO-3: To avoid the potential impact associated with a potential conflict with City tree preservation policies, the following shall be implemented:
• Prior to tree removal, the DBH of protected trees proposed for removal shall be confirmed and documented. For every 6 inches of DBH or fraction thereof removed, two trees of the same species shall be planted on or offsite within the City. Tree planting shall be completed by the City within one year of tree removal in a location to be determined and at the City’s discretion.
City of Napa Utilities
Department
Prior to tree removal activities
MITIGATION MONITORING AND REPORTING PROGRAM
Napa Hidden Glen Remediation Project RCH Group
Draft Initial Study/Mitigated Negative Declaration 3 July 2025 MITIGATION MONITORING AND REPORTING PROGRAM – NAPA HIDDEN GLEN REMEDIATION PROJECT Mitigation Measure Monitoring Agency Implementation Schedule Sign-off
CULTURAL RESOURCES
Mitigation Measure CUL-1: In the event that cultural resources are discovered, regardless of significance, all work shall be halted within a 50-foot radius of the discovery and a qualified archaeologist shall be immediately notified. Any soil or cultural or tribal cultural resources that have been removed shall be retained in as close to the original context as possible until reviewed by a qualified archaeologist and applicable tribal representative. Work shall continue outside of the 50-foot buffer around the discovery. If the find is deemed not significant by the qualified archaeologist and applicable tribal representative, work shall resume within the 50-foot buffer. If the find is deemed significant by the qualified archaeologist, additional work, such as shovel testing or data recovery, shall be required and shall be determined through consultation with the City, State Historic Preservation Office, regulatory agencies, affiliated Tribal governments, or other stakeholders, as appropriate.
City of Napa Utilities
Department
During construction activities
(if cultural resources are
discovered)
Mitigation Measure CUL-2: In the event of discovery or recognition of any human remains, the stipulations of State of California Health and Safety Code Section 7050.5 shall be followed to treat the discovery. The Napa County Coroner shall be notified immediately of the discovery of human remains and no further disturbance shall occur in the area of the discovery until the Napa County Coroner has made a determination of origin and disposition of the remains pursuant to PRC Section 5097.98. If the human remains are determined to be of Native American origin, the Coroner shall notify the NAHC, who will determine and notify a Most Likely Descendent (MLD). Treatment of the remains should be determined in consultation with the MLD and appropriate regulatory agencies.
City of Napa Utilities
Department
During construction activities
(if human remains are
discovered)
I I
MITIGATION MONITORING AND REPORTING PROGRAM
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