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Project Title: |
Green Valley Road Single-Family Residential Rezone and Minor Subdivision |
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County File(s): |
CDRZ23-03271 & CDMS23-00005 |
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Applicant: |
Benoit McVeigh, dk Engineering |
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Owner: |
George M. Moore |
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Zoning: |
A-2, General Agricultural District |
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General Plan: |
SL, Single-Family Residential - Low Density (RL, Residential Low Density) |
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Site Address/Location: |
1921 Green Valley Road, Alamo, CA (Assessor’s Parcel Numbers: 194-070-015 and 194-070-018) |
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California Environmental Quality Act (CEQA) Status: |
Mitigated Negative Declaration (MND), SCH #2025031276 |
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Project Planner: |
Syd Sotoodeh, Senior Planner; (925) 655-2877; syd.sotoodeh@dcd.cccounty.us |
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Staff Recommendation: |
Approve (See Section II for Full Recommendation) |
I. PROJECT SUMMARY
The applicant requests approval of a rezone from an A-2, General Agricultural District to R-40 Single-Family Residential District, and a vesting tentative map to subdivide the subject 2-acre property into two lots, an approximately 0.95-acre Parcel A and an approximately 1.05-acre Parcel B. The applicant has requested variances to the requirements of the R-40 zoning district standards to allow a 0-foot front setback and an 8-foot side yard for the construction of retaining Wall #1 and to allow a 5-foot front setback for the construction of retaining Wall #3. The applicant also requests an exception to County Title 9 standards requiring the undergrounding of existing utilities along the Green Valley Road frontage. Site improvements include expanding the existing driveway where it connects to Green Valley Road, installing new utilities and infrastructure, and constructing stormwater and drainage infrastructure. The applicant also requests approval of a tree permit for the removal of eight code-protected trees and to allow work within the driplines of four code-protected trees for the demolition of an existing barn, grading including ±330 cubic yards (CYS) of cut and ±540 CYS of fill for a net 210 CYS, construction of retaining walls and other site improvements, and construction of a new two-story residence on proposed Parcel B. An existing residence on proposed Parcel A would remain unchanged.
The planning commission will consider and make recommendations to the Contra Costa County Board of Supervisors on the following:
• A rezoning of the Project site from an A-2, General Agricultural District to a R-40, Single-Family Residential District;
• A Vesting Tentative Map (VTM) to subdivide the subject property into two lots, an approximately 0.95-acre Parcel A and an approximately 1.05-acre Parcel B;
• Variances to allow a 0-foot and a 5-foot front setback (where 25 feet is required) and an 8-foot side yard (where 20 feet is required) for the construction of two retaining walls;
• An exception to the requirements and regulations of County Code Title 9, Chapter 96-10, for undergrounding of overhead utility services; and,
• A Tree Permit to allow the removal of eight code-protected trees (three valley oaks, one coast live oak, three coast redwoods, and one ash with a combined diameter of 149 inches), and work within the driplines of four code-protected trees (one valley oak and three coast live oaks with a combined diameter of 79 inches).
II. RECOMMENDATION
The Department of Conservation and Development, Community Development Division (CDD) staff recommends that the County Planning Commission:
A. OPEN the public hearing on the Green Valley Road project, RECEIVE testimony, and CLOSE the public hearing.
B. RECOMMEND that the Board of Supervisors:
a. ADOPT the Mitigated Negative Declaration (SCH 2025031276) and Mitigation Monitoring and Reporting Program prepared for the project, and specify that the Department of Conservation and Development (located at 30 Muir Road, Martinez, CA) is the custodian of the documents and other materials, which constitute the record of proceedings upon which this decision is based;
b. ADOPT an ordinance rezoning the approximately 2-acre project site and adjacent public right-of-way to an R-40, Single-Family Residential (R-40) district (County File #CDRZ23-03271);
c. APPROVE the Vesting Tentative Map for the Project (County File #CDMS23-00005).
d. APPROVE variances to allow a 0-foot front setback (where 25 feet is required) and an 8-foot side yard (where 20 feet is required) for construction of retaining “Wall #1” and to allow a 5-foot front setback (where 25 feet is required) for construction of retaining “Wall #3”.
e. AUTHORIZE an exception to the requirements and regulations of County Code Title 9, County Code Chapter 96-10, for undergrounding of existing overhead utility services.
f. APPROVE the Tree Permit to allow the removal of eight (8) code-protected trees and work within the driplines of four (4) code-protected trees.
g. APPROVE the findings in support of the Project.
h. APPROVE the Project conditions of approval.
i. APPROVE the Green Valley Road 2-Lot Subdivision Project.
j. DIRECT the Department of Conservation and Development to file a CEQA Notice of Determination with the County Clerk.
III. GENERAL INFORMATION
A. General Plan: As of November 5, 2024, the subject property is located within an RVL, Residential Very Low-Density General Plan land use designation (County General Plan Envision 2045). When the application was deemed “complete” for processing on October 7, 2024, the property was located in a SL, Single-Family Residential - Low Density General Plan land use designation.
B. Zoning: The subject property is located within an A-2, General Agricultural District.
C. California Environmental Quality Act (CEQA) Compliance: An Initial Study and Mitigated Negative Declaration (IS/MND) identified potentially significant impacts in the areas of biological resources, cultural and tribal cultural resources, geology & soils, wildfire, and mandatory findings of significance, and identified mitigation measures to reduce such impacts to less-than-significant levels. The IS/MND and corresponding documents were posted for public review on March 25, 2025. The public comment period for accepting comments on the adequacy of the environmental documents extended from March 26, 2025, through April 24, 2025. Three comment letters were received via email within the comment period. The letters received are discussed in further detail in the CEQA Public Comment section of this report.
D. Tribal Cultural Resources: In accordance with Section 21080.3.1 of the California Public Resources Code, Notices of Opportunity to Request Consultation were mailed to the Wilton Rancheria on October 31, 2024, and to the Confederated Villages of Lisjan Nation on November 1, 2024. These are the two California Native American tribes that have requested notification of proposed projects. Pursuant to Section 21080.3.1(d), there was a 30-day time period for each of the tribes to either request or decline consultation in writing for this project. No response has been received from the Wilton Rancheria. However, responses from the Confederated Villages of Lisjan Nation were received on December 11, 2024, and December 12, 2024, in which the Tribal Chair requested consultation due to the proximity of the project to Green Valley Creek. Ultimately, in email correspondence received on January 27, 2025, the Tribal Chair of the Confederated Villages of Lisjan Nation requested that as the project area may be sensitive for Tribal Cultural Resources, they be contacted if any cultural resources of Native American origin are inadvertently found during grading or construction on the project site. Mitigation measures CUL-1 through CUL-3 for Cultural and Tribal Cultural Resources have been included in the MND and also in the conditions of approval as part of staff’s recommendations (COA #34 to #36). The Tribal Chair of the Confederated Villages of Lisjan Nation indicated that the Tribe has no further information to supply about the proposed site for this subdivision.
E. Lot Creation: The subject property consists of two descriptive tax parcels established as one lot pursuant to the County’s approval of Minor Subdivision #MS66-89 and depicted as Lot C on a Record of Survey recorded on June 10, 1966 (43 LSM 13).
F. Prior County Files Related to the Property:
a. MS66-89: A minor subdivision to establish 4 new lots, approved in May of 1966 and recorded as Record of Survey (LSM) Book 43, Page 13, on June 10, 1966.
b. ZI01-9011: A small lot design review to construct a new steel and wood retaining wall to replace an older wood wall around the east and south side of an existing residence, approved on March 19, 2011.
IV. SITE/AREA DESCRIPTION
The subject property is an approximately 2-acre, irregularly shaped lot comprised of two tax parcels located on Green Valley Road in the Alamo area of the County, approximately 1/4-mile north of Stone Valley Road and approximately 1-3/4 miles northeast of I-680. The Green Valley trail head with access to the Summit Trail at the base of Mt. Diablo is located approximately 962 feet north of the subject property. The West Branch of Green Valley Creek is located approximately 378 feet west of the project site. Located within the foothills of Mt. Diablo and situated at the bottom of a low hill that is part of a series of low ridges and small canyons to the west, the subject property has fairly steep topography rising approximately 140 feet from the eastern property line fronting Green Valley Road to the western property line, with an average slope of approximately 53 percent. The project site where an existing barn is located has been leveled where slopes are less than 15 percent. The existing driveway is fairly steep and narrow and bisects the property above the barn. Nineteen mature, code-protected trees (measuring more than 6.5-inches in diameter) on the subject property and seventeen mature, non-code-protected trees in the public right-of-way along the frontage of the subject property were inventoried by the project arborist.
Developments in the surrounding unincorporated area are located within a variety of single-family residential zoning districts (R-10, R-15, R-20, R-40, or R-100), Planned Unit (P-1) districts, and General Agriculture (A-2) districts. The project site within an A-2 General Agricultural (A-2) zoning district is developed with a single-family residence, driveway, and barn. The surrounding area of Alamo is predominantly developed with single-family residences. Other nearby land uses include Monte Vista High School and Los Cerros Middle School, Monte Vista swimming pool and sports complex, and Oak Hill Park, all approximately 1/2-mile south of the project site. Nearby town centers include Alamo (e.g., Alamo Plaza) approximately 3 miles to the west and downtown Danville approximately 2 miles to the south.
V. PROJECT DESCRIPTION
The applicant requests a rezone of the property from A-2, General Agricultural District to R-40, Single-Family Residential district and approval of a vesting tentative map to subdivide the subject 2-acre property into two parcels, resulting in a 0.95-acre (gross) Parcel A and a 1.05-acre (gross) Parcel B.
The project proposes one private access and utility easement (PAUE) approximately 25 feet in width on proposed Parcel B. Improvements would be made to an existing driveway within the new PAUE including widening the driveway where it connects to Green Valley Road to approximately 20 feet and repaving portions of the driveway. An improved and widened driveway to the residence on proposed Parcel B would split from the PAUE. The driveway on proposed Parcel A to the existing residence would remain as-is.
Other site improvements include three bioretention filters, a concrete ditch, and trench inlets/drains for stormwater control and drainage. Six retaining walls between zero and nine feet in height are proposed. The applicant has requested variances to the requirements of the R-40 zoning district for the construction of two of the retaining walls that would be over three feet in height:
• 0-foot front setback (where 25 feet is required) and 8-foot side yard (where 20 feet is required) for “Wall No. 1”; and,
• 5-foot front setback (where 25 feet is required) for “Wall No. 3”.
The applicant has also requested an exception from the requirements of Title 9, Chapter 96-10, of the County Ordinance Code related to the undergrounding of existing overhead utility services along the subject property’s Green Valley Road frontage. Water, sewer, electrical, and other utilities extending to the proposed residence on Parcel B would be installed underground. Trenching for those utilities, as well as drainage improvements, would be performed as part of grading. It is anticipated that the project will entail ±330 cubic yards (CYS) of cut and ±540 CYS of fill for a net 210 CYS of grading for site and residential improvements.
The project proposes demolition of an existing barn for the construction of a new 3,496-square-foot, two-story, single-family residence with a 553-square-foot garage, 315-square-foot main floor deck, and 383-square-foot lower floor concrete patio for Parcel B. New development proposed for Parcel A consists of the installation of two bioretention filters for stormwater control. No other changes or improvements are proposed for Parcel A where an existing residence would remain.
The applicant also requests approval of a tree permit for the removal of code-protected trees including three valley oaks, one coast live oak, three coast redwoods, and one ash (trees #106 through #113) with a combined diameter of 149 inches, and to allow work within the driplines of code-protected trees including one valley oak (tree #120) and three coast live oaks (trees #103 through #105) with a combined diameter of 79 inches for the demolition of an existing barn, construction of retaining walls, grading, site/drainage improvements, and construction of a new residence on proposed Parcel B.
VI. AGENCY COMMENTS
Agency comments received by staff are included in Attachment 4. Following are summaries of the agency comments received:
A. San Ramon Valley Fire Protection District: In correspondence dated July 10, 2023, Fire District staff indicated that the applicant would be required to comply with current requirements for water supply and fire department access at time of submittal for construction review and permits. In additional correspondence received on August 26, 2024, the Fire District indicated that they provided directions to the applicant regarding a hairpin approach coming from the south and also advised that a turnaround is not required as the fire department would be able to achieve the required hose pull distance of 200 feet from the top of the driveway. Also, the Fire District indicated that a grooved concrete application is not required as the grade of the new driveway would be under 16 feet. Please refer to the attached correspondence for the details of their comments.
B. East Bay Municipal Utility District (EBMUD): In correspondence dated July 10, 2023, EBMUD staff advised that the applicant should contact EBMUD’s New Business Office to request a water service estimate and that engineering and installation of water mains and services may require a substantial lead time. EBMUD also indicated that water meters are not allowed to be located in driveways and that EBMUD’s Water Service Regulations require applicable water-efficiency measures to be installed at the project sponsor’s expense for the provision of new or expanded water services. EBMUD indicated that due to their limited water supply, all customers should plan for shortages in time of drought. Please refer to the attached correspondence for the details of their comments.
EBMUD also provided comments on April 15, 2025, during the CEQA notification period for the draft Initial Study and Mitigated Negative Declaration (IS/MND) which are addressed in the Final IS/MND (attached).
C. California Historic Resources Information System (CHRIS): In correspondence dated July 12, 2023, staff of the CHRIS indicated that there is no record of any previous cultural resource studies for the proposed project area, therefore, the proposed project has the possibility of containing unrecorded archeological sites or Native American cultural resources sites. In addition, staff of CHRIS recommended that if the project area contains any building or structure that is 45 years or older, a qualified professional conduct a formal CEQA evaluation. Pursuant to the recommendations made by CHRIS, mitigation measures CUL-1 through CUL-3 for Cultural Resources have been included in the MND, and also in the conditions of approval as part of staff’s recommendations (COA #34 to #36). Please refer to the attached correspondence for the details of their comments.
D. County Peer Review Geologist: Darwin Meyers Associates (DMA) provided multiple sets of project comments as the applicant worked to achieve a project that meets preliminary applicable standards. In correspondence dated March 28, 2024, DMA noted that they reviewed the preliminary geotechnical report by GFK Investigation, the preliminary VTM and project plans, and a preliminary Stormwater Control Plan prepared for the proposed project. DMA also indicated that they had reviewed the pertinent geology reports, maps, and soil surveys for the Contra Costa County area. DMA acknowledges that there are steep slopes above the project site and that the project site is located within an Earthquake-Induced Landslide Seismic Hazard Zone (SHZ). According to DMA, the risk of slope failure would be greatest if an earthquake were to happen during the winter rainy season. However, DMA noted that the site is not located in an Alquist-Priolo Earthquake Fault Zone and that GFK indicated there are no landslide deposits present on the project site or the hillside overlooking the project site. Thus, DMA advised that GFK does not regard landslide displacement or ground failure as significant hazards for the project.
The revised VTM and preliminary stormwater control plan submitted on August 19, 2024, were routed to DMA. In correspondence dated September 12, 2024, DMA provided updated comments and recommendations indicating that the analysis and recommendations in GFK’s investigative report remain operative. Based on the revised grading and retaining wall plans for the project, DMA indicated that the project proposes the use of engineered retaining walls with only very low/localized graded slopes with a 3:1 or flatter gradient in lieu of highly graded slopes. Thus, according to DMA the proposed grading is very limited, and the project is designed to avoid adverse effects to or due to the stability of the project site.
The peer-review geologist’s recommendation for the applicant to provide a design-level geotechnical report prior to issuance of a building permit and monitoring work performed during construction have been included as mitigation measures GEO-1 and GEO-2 in the draft MND and also as conditions of approval (COA #37 and #39). Please refer to the attached correspondence for the details of their comments.
E. Alamo Improvement Association (AIA): In correspondence dated April 21, 2024, the AIA Planning Committee indicated although they recommended approval of the project at their July 20, 2023, meeting (letter dated July 23, 2023, attached), they reconsidered the applications at their meeting held on April 18, 2024. The AIA advised that based on the meeting discussions, they rescind their prior recommendation for approval and recommend denial of the applications for rezoning, minor subdivision, tree permit, and setback variances. The AIA noted that necessary setback variances for extensive improvements necessary to create a buildable area on Parcel B and for retaining walls were not described in the original project summary provided to both the AIA and the Alamo MAC but were apparent in project exhibits provided by the applicant to the Alamo MAC. Also, the AIA notes that although the County General Plan designates the R-40, R-20, and R-15 zoning districts as “consistent” with the SL land use designation it also lists all A-districts as “could be consistent”. Thus, the AIA advised that local circumstances should guide a rezoning decision. The AIA also noted that the subject property is located within a large, contiguous area of A-2 zoning and rezoning just one of the 13 contiguously A-2 zoned parcels would create an anomaly and undesirable precedent for the other parcels, and that the proposed subdivision would not be permissible in the A-2 district. The AIA further indicated concerns that the property is extremely steep with an average 50% slope, which is greater than the 26% slope above which the General Plan deems substantial topographic modification inappropriate. Thus, according to the AIA, the proposed subdivision meets two of the findings in Section 66474 of the [California] Subdivision Map Act for denial of the subdivision due to the site not being physically suitable for the proposed density of the development or for any type of development. Finally, the AIA indicated that because the proposed retaining walls extend the entire width of the proposed Parcel [B] in close proximity to Green Valley Road, they would have a substantial visual impact, and that, based on landscaping plans provided by the applicant [to the AIA] there would be difficulty in screening the tallest wall(s) by planting due to a lack of space along the proposed driveway or behind the walls. Please refer to the attached correspondence for the details of their comments.
Staff Response: In their initial recommendation for approval, the AIA indicated that the R-40 Single-Family Residential district is the appropriate residential zoning district for the proposed project. Staff agrees. Aside from lot area and average width, the development standards of the A-2 zoning district are the same as those for the R-40 zoning district. Rezoning is common in this area of Alamo where properties have consistently been rezoned over the years for residential subdivisions, including within the same subdivision that created the subject property. In 1991, Parcel ‘A’, the southernmost parcel of Minor Subdivision 89-66 which created the subject property, was subdivided into Parcels ‘A’ and ‘B’ at which time the two new parcels were also rezoned from A-2 to R-40. As shown on the Rezone exhibit included in the attached project plans, properties in this area of Alamo are located in A-2, R-15, R-20, R-40, R-65, R-100, and P-1 zoning districts, including some parcels that are an “anomaly” in being located outside of a contiguous zoning district.
At the time the subject applications were deemed complete, the subject property and 11 other properties comprised of 13 tax parcels located west of Green Valley Road were located within an SL, Single-Family Residential - Low Density General Plan land use designation. Pursuant to the County General Plan Envision 2045 adopted by the Board of Supervisors on November 5, 2024, these properties are now located within a RVL, Residential Very Low-Density land use designation. Although it does not apply to the subject applications, the RVL designation would apply to future applications for the subject property. The RVL designation has been deemed appropriate for transitions between urban development and agricultural/rural areas and for constrained sites where reduced densities are justified, and the R-40 zoning district is consistent with this designation. The 12 properties located in this designation are in a transitional area as they are located between typically urban developments to the north, south, and east, and undeveloped open space to the west (e.g., East Bay Regional Park District land designated Parks and Recreation or Resource Conservation). Like the proposed project, typical development in RVL includes detached single-family units on lots that are approximately 1 acre or larger and small-scale agricultural activities. Of the 12 properties within the SL/RVL land use designation and A-2 zoning district, only three are larger than 5 acres as required in an A-2 district, with the rest ranging between 0.92 and 3.26 acres in area. All are developed with single-family residential uses, including three homes that were constructed on top of the ridge above the subject property and overlooking Green Valley Road and several homes that were constructed on lots with 26 percent or greater slopes.
Regarding the variances that the AIA identified, the R-40 district requires a 20-foot other (or secondary) setback for corner lots which is also applicable to access easements. Pursuant to County Code section 82-4.244(d), setbacks on lots that are 40,000 square feet or more are measured from property lines and not the edge of existing or proposed access easements. Therefore, although there is a proposed access easement, the “other” setback for a corner lot does not apply and there is no secondary front setback variance required for the proposed residence. The applicant submitted a revised vesting tentative map and revised site/development plans to the CDD on August 19, 2024. The revised design reduces the number, length, and height of proposed retaining walls. As shown on the plans, the retaining walls do not span the entire length of proposed Parcel B’s frontage.
Thus, based on the above, staff disagrees that the proposed rezoning to R-40, subdivision of the property into two new lots, and development of one new single-family residence is an anomaly and would set a precedence as this pattern of development has already been established in this area of Alamo. In addition, it is typical for variances for reduced setbacks to be granted for retaining walls in hilly areas of the County. The retaining walls necessary for driveway improvements would provide safer access to the existing residence on proposed Parcel A including Fire District access and would likely be necessary in the future even if the subdivision and development was not proposed.
F. Contra Costa County Public Works Department, Engineering Services: The County Public Works Department, Engineering Services Division provided multiple sets of project comments as they worked with the applicant to achieve a project design that met applicable standards. In their most recent correspondence and staff report dated September 3, 2025, Public Works staff provided comments and recommended conditions of approval for the project relating to traffic and circulation, underground utilities, drainage and stormwater control management, floodplain management, lighting district annexation, area of benefit fees and drainage area fee and creek mitigation, and findings for the requested exceptions to Title 9 requirements. Public Works' recommendations have been included in the conditions of approval as part of staff’s recommendations (COA #43 to #69). Please refer to the attached correspondence for the details of their comments.
G. Alamo Municipal Advisory Council (MAC): The project proposal was considered by the Alamo MAC at their monthly meeting held on April 9, 2024. In correspondence to CDD staff, the Alamo MAC chair indicated that a motion to approve the application as presented by the applicant was carried and passed 5 to 2 to recommend approval with conditions requiring the applicant to screen all retaining walls with trees, shrubs, and vines, and that the geotechnical report be prepared to address the impacts of grading, cut and fill on the six adjoining properties. A requirement for screening the new retaining walls to the extent possible has been included in the conditions of approval as part of staff’s recommendations (COA #23). Please refer to the attached correspondence for the details of their comments.
H. Central Contra Costa Sanitary District (Central San): In correspondence dated March 25, 2025, Central San staff indicated that the project site is located within Central San’s service area and is currently receiving sanitary sewer service. Central San staff also indicated that the side sewer connection to the existing residence on Parcel A appears to traverse proposed Parcel B to connect to an existing public manhole in Green Valley Road; thus, land rights will need to be dedicated if the existing side sewer is to remain as-is, or the applicant may choose to relocate the existing side sewer. Central San staff advised that the applicant would be responsible for submitting plans to Central San for review prior to receiving a final building permit. Please refer to the attached correspondence for the details of their comments.
I. Additional Agencies: Comments were solicited from the Contra Costa Couty Building Inspection Division, the Contra Costa County Grading Inspection Division, the Department of Conservation and Development Transportation Planning, the Department of Conservation and Development Advance Planning, Contra Costa Environmental Health Division (CCEHD), and Contra Costa Mosquito & Vector Control District. No comments were received from these agencies prior to the preparation of this report.
VII. CEQA PUBLIC COMMENTS
A CEQA Initial Study was prepared indicating that, with mitigations, no significant environmental impacts would be created by the proposed project. The proposed rezone, two-lot minor subdivision, grading and site improvements, and development of proposed Parcel B with a new single-family residence may affect the quality of the environment. However, the impacts would be reduced to less than significant levels with the adoption of the recommended mitigation measures as specified in the attached Mitigation Monitoring and Reporting Program (MMRP). Mitigation measures in the areas of biological resources, cultural and tribal cultural resources, geology and soils, and wildfire have been added as conditions of approval for the project and will be implemented to reduce project impacts to less-than-significant levels.
An Initial Study and Mitigated Negative Declaration (MND) for the proposed project was posted for public review on March 25, 2025. The public comment period for accepting comments on the adequacy of the revised environmental documents extended from March 26, 2025, through April 24, 2025. During that time three comment letters were received from the California Department of Toxic Substances Control, the East Bay Municipal Utility District (EBMUD), and David J. Bowie on behalf of the Kimberwicke Court neighborhood.
Staff has prepared a revised IS/MND for the project, including responses to the comments received or staff-initiated text changes, either to provide additional clarifying information or to correct typographical errors. The text changes are not the result of any new avoidable, significant effect and do not alter the effectiveness of any mitigation included in the pertinent section. None of the mitigations identified in the IS/MND circulated on March 25, 2025, have been revised and no new mitigations have been added. New text in the revised IS/MND is shown in underline and deleted text is shown in strikeout.
Below is a summary of the comments that address environmentally related issues discussed in the MND, and staff’s responses to those comments.
A. Letter from the State of California Department of Toxic Substances Control, received April 3, 2025
1. Comment - Contaminants of Concern: A number of contaminants of concern (COCs) can be present on agricultural lands and should be considered when converting such lands for residential use. The lead agency shall identify the amounts of pesticides and organochlorine pesticides (OCPs), or other COCs historically used on the property and take appropriate actions to mitigate.
Staff Response: The applicant submitted a Phase 1 Environmental Site Assessment (ESA) Report prepared by ALFA Environmental Assessment Services (ALFA) for the project (June 9, 2025) which found that there is no evidence of the use, storage, or disposal of COCs or potentially hazardous materials related to agricultural uses on the subject property. In addition, based on their research, ALFA found no evidence that the subject property was used for any agricultural purposes that would have resulted in COCs related to agricultural crops being used. Staff has revised Section 9 - Hazards and Hazardous Materials of the Initial Study as shown on the attached IS/MND.
2. Comment - Imported Soil/Fill: DTSC recommends that all imported soil and fill material be tested to assess any contaminants of concern (COC) to meet screening levels outlined in DTSC's Preliminary Endangerment Assessment (PEA) Guidance Manual and advises referencing the DTSC Information Advisory Clean Imported Material Fact Sheet if importing fill is necessary.
Staff Response: As reported in the Description of Project of the Initial Study, grading would be minimal with a net 210 cubic yards of fill imported to the site, primarily for proposed driveway improvements. The comment does not specify inadequacies in the draft IS/MND or otherwise challenge the environmental review. Nonetheless, staff has recommended as a condition of approval that all imported soil and fill material be tested to assess any contaminants of concern and documentation submitted to the CDD and County Building Inspection (BI) verifying the testing results (COA #29 and #30).
B. Letter from the East Bay Municipal Utility District (EBMUD), received April 14, 2025
1. Comment: EBMUD advises that the project would be served by the EBMUD Diablo Pressure Zone, that water service is available, and that separate meters for each lot will be required. EBMUD provided information on how to request water service when development plans are finalized. In addition, EBMUD indicates that the project presents an opportunity to incorporate water conservation measures including those required by State Assembly Bill 325 (Model Water Efficient Landscape Ordinance).
Staff Response: In general, comments received from EBMUD during the CEQA notification period provided additional guidelines that apply to the proposed project but did not challenge the adequacy of the environmental document. The majority of the comments received on April 14, 2025, are similar to comments typically provided to the CDD in response to an Agency Comment Request during the project review period. The project would be required to comply with the County’s Model Water Efficient Landscape Ordinance if new or renovated landscaping is proposed and as such would comply with State Assembly Bill 325.
C. Letter from David J. Bowie, office of Bowie & Schaffer, Attorneys at Law, received April 22, 2025
Many of the comments received from David J. Bowie during the CEQA notification period (e.g., whether or not the subject property should be rezoned, community values and the political process of zoning decisions, the need for variances for setbacks) pertain to the merits of the project and did not challenge the adequacy of the environmental document. A summary of the comments that do challenge the adequacy of the environmental document are as follows:
1. Comment: The subject property has been zoned A-2 since its creation in/around 1966 and is consistent with the General Plan. The subject property is steep (at an average slope of 53%) and entirely unsuitable for flat land development and density. Other residential R-20 and R-40 zoning districts are in the general area; however, the subject property is one of a number of adjoining parcels in steep terrain that share an A-2 district. In addition, although the County’s Slope Density Overlay District does not apply to the property, the lot size dimensions required in the A-2 district are consistent with a basic principle that the size of lots should increase and density decrease as the steepness of the terrain increases.
Staff Response: As discussed in Section 7 - Geology and Soils of the Initial Study, a Geotechnical Investigation was prepared for the proposed minor subdivision and development of site improvements and a new residence on proposed Parcel B. In addition, the findings in the Geotechnical Investigation were peer-reviewed by the County’s peer review geologist. Potentially significant impacts were identified due to potential seismicity/ground shaking and the risk of slope failure during earthquakes. Mitigation measures related to Geology and Soils have been included in the MMRP (GEO-1 and GEO-2) and related conditions of approval have been included as part of staff’s recommendations to reduce any potentially significant geologic/geotechnical impacts including earthquake-induced landslides, slope instability and failure, and other hazards to less than significant levels. As discussed in Section 11 - Land Use and Planning of the Initial Study, the subject property is located within a Single-Family Residential, Low Density (SL) General Plan land use designation. The subject property is not located in an SD-1, Slope Density and Hillside Development Combining District. Based on Table 3-5 of the General Plan, the R-40 zoning district is consistent with the SL General Plan land use designation, and all Agricultural (A-) zoning districts may be consistent with the SL designation.
2. Comment: The MND describes the subject property as an approximately 2-acre irregularly shaped lot with two separate assessor’s parcel numbers. The proposal is to rezone from A-2 to R-40 then subdivide the existing parcels into two separate lots, one of 0.95 gross acres and the other of 1.05 gross acres. The R-40 zoning district requires a minimum lot size of 40,000 square feet excluding rights of way from its calculation. The MND describes plans for a right of way ranging from 16 to 30 feet in width and at least 200 feet in length. Although the area of rights of way have not been calculated, it appears that neither resulting lot from an approved subdivision would meet R-40 minimum lot area and that neither would meet other requirements of the district for setbacks.
Staff Response: The comments do not challenge the adequacy of the Description of Project of the Initial Study which correctly describes the proposed subdivision of one lot comprised of two tax parcels which would result in two parcels, one that is 0.95 gross acres (approximately 41,554 square feet) and one that is 1.05 gross acres (approximately 45,745 square feet). However, staff has revised paragraph one of the Initial Study Description of Project to clarify that access to proposed Parcels A and B would be through a private access and utility easement (PAUE) that is 25 feet in width.
As described in Section 11 - Land Use and Planning of the Initial Study, the proposed subdivision is consistent with the minimum lot area, average width, and depth requirements of the R-40 zoning district. Although net acreage excluding private access easements and rights-of way is calculated to determine residential densities (e.g., 1 unit per net acre), private access easements and rights-of way are not excluded from the minimum lot size required by any zoning district including the R-40 district. Also, the project requests approval of variances for reduced setbacks and side yard for two retaining walls, which is also accurately described in the Initial Study. The setback and yard standards are the same for both A-2 and R-40 zoning districts and aside from the variances requested for retaining walls, the project is consistent with those standards. Staff considers that the findings exist to grant approval of the variances to construct two retaining walls, as indicated in the attached Findings section of this report.
3. Comment: In considering if the project would cause significant environmental impact due to conflict with any land use plan, policy, or regulation, the MND disregards potential conflicts with land use policies by its characterization of the density as falling within an acceptable range and broadly approximating the “net” area calculations in “cavalier fashion.” The MND does not draw distinction between environmental policies and the arbitrary and unjustified proposal to simply advocate for R-40 zoning and ignoring that the project does not meet minimum standards and variances would be required. Thus, a less dense zoning district such as R-65 would be more consistent and avoid the creation of substandard lots requiring variances.
Staff Response: The project’s consistency with the allowed densities in the SL, Single-Family Residential General Plan land use designation and the R-40 district’s consistency with the SL land use designation, and potentially significant impacts due to rezoning, subdividing, or development of the subject property is discussed in the Initial Study in Section 1 - Aesthetics, Section 2 - Agricultural and Forest Resources, Section 3 - Air Quality, Section 11 - Land Use and Planning, and Section 21 - Mandatory Findings of Significance. Where potentially significant impacts were identified in the Initial Study, mitigation measures were incorporated to reduce those impacts to less than significant levels as indicated in the Mitigation Monitoring and Reporting Program.
The Description of Project of the Initial Study correctly describes the proposed subdivision of the subject property which would result in two parcels, one that is 0.95 gross acres (approximately 41,554 square feet) and one that is 1.05 gross acres (approximately 45,745 square feet). As mentioned above in response to Mr. Bowie’s Comment #2, net acreage excludes private access easements and rights-of-way and is calculated to determine residential densities. As such, excluding the proposed access easement, the total net acreage of the 2-acre project site is approximately 1.9 acres. The net acreage was not calculated by staff but is based on the Vesting Tentative Map that was prepared by a licensed engineer. As proposed, the two-lot minor subdivision results in a density of approximately 1 unit per net acre, which is within the range of units allowed in the SL, Single-Family Residential General Plan land use designation. Also, although the project would not meet minimum front and side yard setback requirements for construction of two retaining walls, the project would not create any substandard lots. Staff considers that the findings exist to grant approval of the requested variances to allow substandard setbacks.
4. Comment: The MND failed to consider the cumulative impacts of development within the area. The MND is inadequate in that it fails to consider the environmental impact related to its “cavalier” proposed rezoning of the property to R-40. There are many properties that are similarly situated to the subject property which are currently designated A-2. The rezoning of the property to R-40 would likely result in being determined to as “spot-zoning” or if approved would act as a catalyst for future rezoning and subdivision applications. There is no discussion as to why a denser zoning district has been proposed over less dense categories.
Staff Response: The project’s cumulative impacts due to rezoning and subdivision within the vicinity of the subject property is discussed in Section 21 - Mandatory Findings of Significance of the Initial Study which found that the subject property is one of the few in the immediate vicinity that is further subdividable and that the County is not currently processing any discretionary applications for residential or non-residential development for properties contiguous to the site or within at least five miles of the project site. The project site is in an area of Alamo located in a variety of zoning districts (A-2, R-15, R-20, R-40, R-65, R-100, and P-1 zoning districts), and rezoning is common in this area of Alamo where properties have similarly been rezoned over the years for residential subdivisions. Thus, if granted, the result of rezoning the subject property from A-2 to R-40 would not constitute “spot-zoning”. The project’s proposed density and consistency with the intent and purpose of the SL, Single-Family Residential General Plan land use designation including the allowed density, as well as the consistency of the proposed R-40 zoning district for the subject property is discussed in Section 11 - Land Use and Planning of the Initial Study.
VIII. STAFF ANALYSIS AND DISCUSSION
A. General Plan:
On November 5, 2024, the County Board of Supervisors adopted the Contra Costa County 2045 General Plan. The subject Minor Subdivision and Rezoning applications were deemed “complete” for processing on October 7, 2024. Therefore, the County General Plan 2005-2020 applies and is cited throughout this Initial Study.
Land Use Element:
The subject property is located within a Single-Family Residential, Low Density (SL) land use designation. Generally speaking, the purpose of the SL designation is to allow for the development of detached single-family residences and accessory buildings and structures, while also allowing for secondary uses that are considered to be compatible with low density homes (e.g., ADUs, churches, home occupations, small residential and child care facilities). The SL land use designation allows for a density of 1 to 2.9 units per net acre. According to Table 3-4 of the 2005-2020 County General Plan, “Net acreage includes all land area used exclusively for residential purposes, and excludes streets, highways, and all other public rights-of-way.” Due to the proposed access easement, the total net acreage of the approximately 2-acre project site is approximately 1.9 acres. As proposed, the two-lot minor subdivision would result in a density of approximately 1 unit per net acre, which is within the range of units allowed. Thus, the proposed subdivision of land will not alter or conflict with the density or result in more residential units than is allowed for the project site. The application proposes the rezone of the subject property from A-2, General Agricultural District to R-40, Single-Family Residential. Based on Table 3-5 of the General Plan (Consistency Between the General Plan and Zoning Ordinance), the R-40 zoning district is consistent with the SL General Plan land use designation. Only residential uses are proposed with this application.
Pursuant to the new County General Plan Envision 2045 adopted by the Board of Supervisors on November 5, 2024, the subject property is now located within a RVL, Residential Very Low-Density land use designation with a density of less than or equal to 1 unit per acre. Although it does not apply to the subject applications, the RVL designation would apply to future applications for the subject property. The RVL designation is appropriate for transitions between urban development and agricultural/rural areas and for constrained sites where reduced densities are justified. Typical development in RVL includes detached single-family units on lots that are approximately 1 acre or larger and small-scale agricultural activities. In addition to R-65 and R-100 zoning, the R-40 zoning district is consistent with RVL. The proposed project would result in two parcels that are approximately 1 acre each and is located on a lot that is a transitional area between urban development to the north, south, and east and open space/park land to the west that is located in Parks and Recreation or Resource Conservation land use designations. A density of two lots would be allowed for the 2-acre (1.90-acre net) property, and the proposed subdivision of land will not alter or conflict with the density or result in more residential units than is allowed for the project site in RVL.
Policies for the Alamo-Diablo-Blackhawk Area:
General Plan Policies 3-115 to 3-125 are specific to the guidance of uses and development for the Alamo-Diablo-Blackhawk areas of the County. Policies 3-115, 3-116, 3-122, and 3-124 are applicable to residential development or rezoning within the Alamo area. As such, these are the area policies that are applicable to the project, as discussed below:
• The intent of Policies 3-115 and 3-116 is to promote the individuality and unique character of each community based on existing community images, and to promote the character of the area as one of predominantly single-family residences. After approval of the proposed two-lot minor subdivision application, one existing single-family residence would remain on Parcel A and a single-family residence would be built on Parcel B. Each parcel would be approximately 1 acre in area, which is similar to other lots in the vicinity. Thus, the project would have no impact on the character of the community and established single-family residential neighborhood in which the project is located.
• The intent of Policy 3-122 is to ensure that when rezoning in Alamo, the appropriate zoning will include Single-Family Residential districts R-20, R-40, R-65, and R-100, and Planned Unit district P-1. If approved, the subject property would be rezoned to R-40 which is consistent with Policy 3-122 and the variety of residential zoning districts in the surrounding Alamo area.
• The intent of Policy 3-124 is to require developments to be reviewed to ensure the continued rural character of the area. The surrounding area is generally developed with single-family residences, roads, some curbs, and some sidewalks as would typically be found in a suburban environment, and there is an element of rural character in the immediate vicinity of the project site along Green Valley Road, and due to open, rolling hillsides to the west that are developed with very low density residential uses and undeveloped open space further to the west. Based on comments received from staff of the Public Works Department, the project would not be required to install curb and sidewalk improvements along its Green Valley Road frontage. In addition, the steepest area of the subject property west of the existing driveway would remain undeveloped, natural open space. Thus, the project would maintain the “rural” character of the area.
The two-lot minor subdivision does not involve an amendment to the General Plan land use designation, and the resultant parcels would remain residential in nature and use. The development of one new single-family residence on proposed Parcel B would remain compatible with the predominantly residential development of the area.
Conservation Element:
The Conservation Element of the General Plan lists three overall conservation goals (8A-8C):
• Conservation Goal 8A: To preserve and protect the ecological resources of the County.
• Conservation Goal 8B: To conserve the natural resources of the County through control of the direction, extent, and timing of urban growth.
• Conservation Goal 8C: To achieve a balance of uses of the County’s natural and developed resources to meet the social and economic needs of the County’s residents.
The subject property is located approximately 3 miles west of the lower elevations of Mt. Diablo State Park. The entire project site has been previously disturbed, primarily through maintenance of the property that is developed with one single-family residence and a barn with a shared driveway to each structure. According to the California Department of Conservation’s California Important Farmland Finder map, the western area (approximately half) of the subject property is within an area deemed to be “Grazing Land” which is considered to contain vegetation that is suited to livestock grazing whereas the eastern area (approximately half) of the subject property along the Green Valley Road frontage is within an area deemed to be “Urban and Built-Up Land” which is considered to be occupied by or suitable for urban structures with a building density of at least one unit per 1.5 acres. There is no evidence that the subject property is utilized for grazing or other agricultural uses and is not considered to be prime farmland. The project site is not located within an area of known ecological sensitivity (Figure 8-1, County General Plan) and the project does not affect any known natural resources. Through the implementation of mitigation measures identified in the draft IS/MND prepared for the project, air quality, biological, geological, or cultural resources in Contra Costa County would not be significantly affected.
B. Rezoning and Consistency with R-40 Zoning District: The project proposes to rezone the site from A-2, General Agricultural District to R-40, Single-Family Residential District. The proposed zone change from A-2 to R-40 is consistent with lots in the surrounding area which are designated with a variety of residential, Planned Unit (P-1), and agricultural districts, within an underlying SL General Plan land use designation. The proposed Vesting Tentative Map identifies two new residentially zoned lots.
The standards of the R-40 zoning district require lots to have a specific lot area (size), average width, and depth as summarized in the table below.
|
R-40 Zoning Standard |
Proposed Parcel A |
Proposed Parcel B |
|
Minimum lot area: |
40,000 sq. ft. |
41,554 sq. ft. |
45,745 sq. ft. |
|
Minimum average width of lot: |
140 feet |
282 feet |
299 feet |
|
Minimum lot depth: |
140 feet |
148 feet |
152 feet |
As proposed, the dimensions of the resultant parcels will comply with the minimum lot area, width, and depth standards for the R-40 zoning district.
The R-40 district requires a 25-foot front setback for primary and accessory buildings/structures, a 20-foot side yard with a 40-foot side yard aggregate for primary buildings, and a 15-foot rear side yard. R-40 allows a 3-foot side yard for accessory structures with a minimum 75-foot front setback. The R-40 district requires a 20-foot other setback for corner lots which is also applicable to access easements. Setbacks on lots that are larger than 40,000 square feet are measured from property lines and not the edge of existing or proposed access easements (County Code section 82-4.244(d)). Therefore, although there is a proposed access easement, the “other” setback for a corner lot does not apply.
As designed, the proposed residence for Parcel B is consistent with the minimum front setback, rear yard, side yard, side yard aggregate, and maximum building heights. The applicant has requested variances from the standards to allow a 0-foot front setback and an 8-foot side yard for retaining Wall #1 and to allow a 5-foot front setback for retaining Wall #3. Pursuant to County Code Section 84-16.1602, variances may be granted to modify the provisions in the R-40 district. Staff considers that findings exist to allow the variances for reduced setbacks and a reduced side yard for retaining walls over three feet in height due to the steep topography of the subject property and the need to widen and shore up the existing driveway for safe ingress and egress and improved fire apparatus access. In addition, the use of a shared driveway minimizes the number of curb cuts on Green Valley Road. The proposed two-lot minor subdivision project and proposed residential improvements are consistent with the permitted residential land uses within the R-40 zoning district, and the R-40 zoning district is consistent with the underlying SL General Plan land use designation. Therefore, the project is consistent with the R-40 zoning district.
C. Tree Permit: The subject property contains a number of mature trees, all of which are considered protected trees under the County’s Tree Protection and Preservation Ordinance (County Code Chapter 816-6) due to their size and their presence on a property that is further subdividable if the requested rezone to an R-40 zoning district is approved. If granted, the proposed tree permit would allow for the for the removal of eight code-protected trees (three valley oaks, one coast live oak, three coast redwoods, and one ash with a combined diameter of 149 inches) and would also allow for work within the driplines of four code-protected trees (one valley oak and three coast live oaks with a combined diameter of 79 inches) for anticipated grading, trenching, and construction activities as part of the proposed project on the subject property, primarily on proposed Parcel B. The County’s Tree Preservation and Protection Ordinance is intended to provide for the protection of trees on private property through contingency restitution should altered trees be damaged or removed, while allowing for reasonable enjoyment of private property rights and development. When protected trees are removed, the Ordinance is intended to provide for restitution through the planting of new trees. The reasonable development of the subject property requires the removal of and work within the driplines of code-
protected trees. Therefore, staff considers that the required findings exist to grant approval of a tree permit. Staff has recommended conditions of approval requiring the replacement of removed trees, the protection of trees intended to be preserved, and security deposits to ensure these measures are implemented (COA #16 to #21). Therefore, the proposed project is consistent with the County’s Tree Protection and Preservation Ordinance.
D. Traffic and Circulation: The project has access from Green Valley Road, a County maintained road. The Green Valley Road frontage features a curb that has been partially buried in some locations along its length at places by the elevated earthen shoulder. At this location, Green Valley Road is 30 feet wide within a 60-foot right-of-way and no right-of-way dedication is necessary for this project. The site plan proposes to remove and replace the existing driveway onto Green Valley Road, which is offset by several feet from being in line with the Kimberwicke Court intersection. The new and wider driveway will take a 90-degree turn, providing direct access to the proposed residence and branching onto the existing drive that is to remain. The applicant will be required as a condition of approval to relinquish abutter’s rights of access along the frontage of Green Valley Road, with the exception of the new driveway access. Staff of the Public Works Department have recommended conditions of approval regarding traffic and circulation (COA #44 to #53).
E. Underground Utilities: Chapter 96-10 of the County Ordinance Code requires all new and existing utility distribution facilities to be installed underground. The applicant has requested an exception from the requirement applicable to the existing overhead lines along the site’s Green Valley Road frontage. Considering the character of the area and the scope of this project, Public Works indicated that they would not be averse to the granting of this exception. The required findings for the request for exception pursuant to Chapter 92-6 have been provided and are included as part of the attached Findings. In addition, staff of the Public Works Department has recommended a condition of approval regarding the undergrounding of utilities (COA #56).
F. Drainage: Division 914 of the County Ordinance requires that all storm water entering and/or originating on this property to be collected and conveyed, without diversion and within an adequate storm drainage system, to an adequate natural watercourse having a definable bed and banks or to an existing adequate public storm drainage system which conveys the storm water to an adequate natural watercourse. Based on County elevation data, runoff flows eastward towards Green Valley Road. Submitted plans show that proposed modifications to grading and drainage infrastructure are confined to Parcel “B”. Stormwater infrastructure proposed for Parcel “B” will tie into three separate curb inlets along Green Valley Road. A Stormwater Control Plan (SWCP) is required for applications that will create and/or redevelop impervious surface area exceeding 5,000 square feet in compliance with the County’s Stormwater Management and Discharge Control Ordinance (§1014) and the County’s Municipal Separate Storm Sewer System (MS4) National Pollutant Discharge Elimination System (NPDES) Permit. This project proposes approximately 11,000 square feet of impervious surface with the minor subdivision application, which is above the threshold for requiring submittal of a SWCP. A preliminary SWCP was submitted with the application and was considered adequate for deeming the subject applications complete for processing. Staff of the Public Works Department have recommended conditions of approval regarding drainage and stormwater management (COA #58 to #69).
G. Appropriateness of the Use: The proposed minor subdivision of a 2-acre lot located within a SL, Single-Family Residential - Low Density General Plan land use designation and rezoning of the lot to a single-family residential R-40 zoning district will create more available area for residential development without impacting the existing residential land uses on the subject lot or within the area. The rezoning of the lot from A-2 Agricultural Lands to R-40 Single-Family Residential is consistent with the SL, Single-Family Residential - Low Density General Plan land use designation for the subject property. The project complies with the General Plan policies for land uses and the Alamo-Diablo-Blackhawk Area. The proposed vesting tentative map and residential development also complies with the requirements of the R-40 zoning district and findings have been made for the variance and exception requests to the applicable sections of Titles 8 and 9 of the Contra Costa Code. The project will not result in development that would otherwise impede or negatively impact the surrounding area. Thus, the project is appropriate for the area and satisfies the requirements of the County General Plan and Titles 8 and 9 of the County code.
IX. CONCLUSION
With Conditions of Approval, the proposed project is consistent with applicable policies and standards of the General Plan and zoning code. In addition, an environmental analysis of the project was completed and found that the proposed project would not have a significant impact on the environment with the incorporation of specific mitigations. Therefore, staff recommends approval of County Files #CDRZ23-03271 & CDMS23-00005, based on the attached findings and subject to the attached conditions of approval.
Attachments:
1. Findings and Conditions of Approval
2. Proposed Zoning Map (PreOrdinance_RZ233271)
3. Maps (Parcel Map, General Plan, Zoning, Aerial Photograph)
4. Agency Comments
5. CEQA Public Comments
6. Initial Study and Mitigated Negative Declaration
7. Applicant Acceptance of Mitigations
8. Mitigation and Monitoring Reporting Plan (MMRP, Nov. 17, 2025)
9. Project Plans
10. Presentation Slides