Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
ATHERTON HOUSING ELEMENT UPDATE
MITIGATION MONITORING AND REPORTING PROGRAM
MITIGATION MEASURE IMPLEMENTATION RESPONSIBLE
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AIR QUALITY
AQ-1: During all construction activities associated with future development facilitated by the 2023 – 2031 Housing Element, the contractor shall implement the latest BAAQMD recommended Best Management Practices (BMPs) to control for fugitive dust and exhaust as follows:
1. All exposed surfaces (e.g., parking areas, staging areas, soil piles, graded areas, and unpaved access roads) shall be watered two times per day.
2. All haul trucks transporting soil, sand, or other loose material shall be covered.
3. All visible mud and 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.
4. All vehicle speeds on unpaved roads shall be limited to 15 miles per hour (mph).
5. All roadways, driveways, and sidewalks to be paved shall be completed as soon as practicable. Building pads shall be laid as soon as practicable after grading unless seeding or soil binders are used.
6. All excavation, grading, and/or demolition activities shall be suspended when average wind speeds exceed 20 mph.
7. All trucks and equipment, including their tires, shall be washed off prior to leaving the site.
8. 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 layer of wood chips, mulch, or gravel.
9. A publicly visible sign with the telephone number and person to contact at the Lead Agency regarding dust complaints shall be posted on the project site prior to the initiation of construction activities. This person shall respond and take corrective action within 48 hours. The Air District’s phone During
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Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
ATHERTON HOUSING ELEMENT UPDATE
MITIGATION MONITORING AND REPORTING PROGRAM
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number shall also be visible to ensure compliance with applicable regulations.
AQ-2: Require multi-unit residential projects, larger than 10 units, and within 1,000 feet of existing sensitive receptors, as defined by BAAQMD to prepare a project-specific construction health risk assessment (HRA). If the HRA demonstrates, to the satisfaction of the Town, that the health risk exposures for adjacent receptors will be less than BAAQMD project-level thresholds, then additional mitigation would be unnecessary. However, if the HRA demonstrates that health risks would exceed BAAQMD project level thresholds, additional feasible mitigation shall be analyzed and adopted to further reduce risks below the BAAQMD project-level thresholds. Measures to avoid significant construction health risks impacts that could be included in projects, depending on the results of an HRA could include the following:
1. Use Tier 4 engines for all off-road equipment greater than 50 horsepower (hp) and operating for more than 20 total hours over the entire duration of construction activities.
2. Use diesel trucks with 2010 or later compliant model year engines during construction.
3. Use renewable diesel during construction.
4. Implement enhanced measures to control dust emissions, as recommended by BAAQMD.
5. Use portable electrical equipment where commercially available and practicable to complete construction. Construction contractors shall utilize electrical grid power instead of diesel generators when: (1) grid power is available at the construction site; (2) when construction of temporary power lines are not necessary in order to provide power to portions of the site distant from existing utility lines; (3) when use of portable extension lines is practicable given construction safety and operational limitations; and (4) Prior to
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Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
ATHERTON HOUSING ELEMENT UPDATE
MITIGATION MONITORING AND REPORTING PROGRAM
MITIGATION MEASURE IMPLEMENTATION RESPONSIBLE
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when use of electrical grid power does not compromise the construction schedule.
AQ-3: Prior to commencing construction activities on sites identified for residential development in the 2023 – 2031 Housing Element, the applicant/contractor shall prepare a site-specific Health Risk Assessment (HRA) for projects affected by Toxic Air Contaminant (TAC) sources. If the HRA demonstrates to the satisfaction of the Town, that the health risk exposures for sensitive receptors will be less than BAAQMD project-level thresholds, then additional mitigation would be unnecessary. However, if the HRA demonstrates that health risks would exceed BAAQMD project level thresholds, additional feasible on- and off-site mitigation shall be analyzed by the applicant to help reduce risks below the BAAQMD project-level threshold. Such measures to be evaluated may include enhanced ventilation systems with filtration capable of reducing TAC exposure such that health risks are reduced to acceptable levels. During Construction Project
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BIOLOGICAL RESOURCES
BIO-1: Prior to the Town of Atherton’s approval of development on the proposed Housing Element Update sites, special-status plant surveys shall be conducted by a qualified botanist in appropriate habitats during the appropriate period (congdon’s tarplant’s blooming period is from May through November; crystal springs lessingia’s blooming period is from July through October; smallflowered monolopia’s blooming period is from March through July; white-rayed pentachaeta’s blooming period is from March through May; and fragrant fritillary’s blooming period is from February through April) in which the species are most identifiable. Project construction shall not be initiated until all specialstatus plant surveys are completed and subsequent mitigation, if deemed necessary by the qualified botanist, is implemented. If the special-status plant species are identified in these surveys, those individuals or populations shall be avoided to the maximum extent possible. If avoidance is not possible, then other suitable measures and mitigations shall be developed in consultation with Prior to Approval Project
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Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
ATHERTON HOUSING ELEMENT UPDATE
MITIGATION MONITORING AND REPORTING PROGRAM
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agencies that are responsible for the protection of the subject plant species, based on its protection status [i.e., Town of Atherton (for plants protected by CEQA), CDFW (plants protected by California law/regulation) or USFWS (protected by federal law regulation)]. Appropriate mitigation prescriptions for impacts on special-status plants shall be included as conditions of project approval.
BIO-2: Unless otherwise recommended in site-specific biological assessments prepared for future development of sites identified in the Housing Element, to avoid impacts to the San Francisco dusky-footed woodrat, a species of special concern, a survey prior to the commencement of ground disturbing activities or vegetation removal on subject parcels with suitable vegetation. Since woodrats use their nests year-round, surveys for the rodent species can be conducted at any time of the year. If the woodrat nests are identified, they shall be flagged and delineated on project site maps.
If any woodrat nests are identified, then CDFW shall be contacted immediately to coordinate mitigation. A qualified biologist shall conduct a pre-construction survey for the San Francisco dusky-footed woodrat nests no more than 30 days prior to the onset of site grubbing/grading or construction activities within 50 feet of construction zones. The identified nests shall be avoided, where possible. If avoidance is not possible, the nest(s) should be manually deconstructed when helpless young are not present, typically during the nonbreeding season which is October through January. If it is determined that young may be present during the pre-construction survey, a suitable buffer, depending on the type of impact, nest location, and topography of the nest location, shall be established by the qualified biologist. The non-disturbance buffer typically ranges from 20 to 50 feet. This buffer shall remain in place around the nest until the young are independent enough to successfully move from the nest.
Prior to Building
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Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
ATHERTON HOUSING ELEMENT UPDATE
MITIGATION MONITORING AND REPORTING PROGRAM
MITIGATION MEASURE IMPLEMENTATION RESPONSIBLE
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BIO-3: Unless otherwise recommended in site-specific biological assessments prepared for future development of the Cal Water site identified in the Housing Element, to avoid impacts to burrowing owls protected under the Migratory Bird Treaty Act and Fish and Game Code (§3503, §3503.5 and §3513), a preconstruction survey for burrowing Owls shall be conducted at the Cal Water site (MFO-10) 14 days prior to ground disturbance. Since burrowing owls can recolonize a site only after a few days, time lapses between project activities trigger subsequent take avoidance surveys, including but not limited to a final survey conducted within 24 hours prior to ground disturbance to ensure that the species is not present. Between April 1st and October 15th, low disturbance and medium disturbance activities should have a 200-meter buffer while high disturbance activities should have a 500-meter buffer from occupied nests.
Between October 16th and March 31st, low disturbance activities should have a 50-meter buffer, medium disturbance activities should have a 100-meter buffer from occupied nests, and high disturbance activities should have a 500- meter buffer from occupied nests. No earth-moving activities or other disturbances within the aforementioned buffer zones of occupied burrows.
These buffer zones shall be fenced as well. If burrowing owls are present on the proposed project area, then a qualified biologist would need to delineate the extent of the western burrowing owl habitat on the site. Prior to Building
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Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
BIO-4: Unless otherwise recommended in site-specific biological assessments prepared for future development of sites identified in the Housing Element, to avoid impacts to birds protected under the Migratory Bird Treaty Act and Fish and Game Code (Section 3514), construction activities, including the removal of trees, should occur outside of the bird-nesting season between September 2nd and January 31st. If work occurs between February 1st and September 1st, a pre-construction bird nesting survey shall be conducted within seven days prior to any proposed ground disturbance or vegetation removal on subject parcels that require nesting bird surveys. The bird nesting survey shall include an examination of all buildings onsite, and trees and shrubs onsite and within 200 feet of the subject parcel (i.e., within a zone of influence of nesting birds), not just trees slated for removal. The zone of influence includes areas outside of the project site where birds could be potentially disturbed by earth-moving vibrations and/or other construction-related noises. If any active bird nests are identified onsite or within a zone of influence, then a qualified ornithologist or biologist shall establish a temporary protective construction buffer around the nest(s), conduct a survey to establish behavioral baseline of birds using each nest, and conduct monitoring to ensure it is not disturbed. The nest buffer will be staked or fenced with orange construction fencing to establish a construction exclusion perimeter and shall be adjusted by a qualified biologist as needed to avoid disturbance. The buffer shall be of sufficient size to protect the nesting site from construction-related disturbance. Typically, adequate nesting buffers are 50 feet from the nest site or nest tree dripline for small birds and up to 300 feet for sensitive raptors. Upon completion of nesting surveys, if nesting birds are identified a qualified ornithologist/biologist shall prescribe adequate nesting buffers to protect the nesting birds from harm while the project is being constructed. If continuous monitoring is not feasible, conservative nodisturbance buffer(s) should be established, with the buffer distance based on the tolerance level of the nesting species.
No construction or earth-moving activity shall occur within any established nest protection buffer prior to September 1st unless determined by a qualified ornithologist/biologist responsible for monitoring nesting behavior that the young have left the nest and have attained sufficient flight skills to avoid construction zones, or that the nesting cycle is otherwise completed. At the end of the nesting cycle and the fledging from the bird nest, as determined by a Prior to Building
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Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
qualified biologist, temporary nesting buffers may be removed, and construction may commence in established nesting buffers without further regard for the nest site.
The biologist/ornithologist conducting the surveys shall provide the Town of Atherton with a report detailing the results of the survey and any recommendations required for establishment of protective buffers, if vegetation removal or any ground disturbance occurs between February 1st and September 1st.
Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
ATHERTON HOUSING ELEMENT UPDATE
MITIGATION MONITORING AND REPORTING PROGRAM
MITIGATION MEASURE IMPLEMENTATION RESPONSIBLE
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BIO-5: Unless otherwise recommended in site-specific biological assessments prepared for future development of sites identified in the Housing Element, to avoid impacts to roosting pallid bats or other special-status bat species, building or tree removal shall only be conducted during seasonal periods of bat activity, between August 31 and October 15, when bats would be able to fly and feed independently, and between March 1 and April 1 to avoid hibernating bats, and prior to the formation of maternity colonies. A biologist with at least two years of experience surveying for bats, shall conduct a pre-construction survey of all buildings and trees that would be impacted within 14 days prior to removal or commencement of site improvement activities. If no special-status bats are found during the surveys, then the biologist shall provide a memo summarizing the results of the survey to the Town, and construction activities may commence. If bat roosts are found, then a plan shall be developed by the qualified biologist for removal and exclusion, when there are not dependent young present, in conjunction with the CDFW.
If building or tree removal must occur outside the seasonal activity periods (i.e., between October 16 and the end of February, or between April 2 and August 30), then a qualified biologist, shall conduct pre-construction surveys within 14 days of tree removal, and determine if there are young present (i.e., the biologist will determine if there are maternal roosts). If a maternity site is found, impacts to the maternity site shall be avoided by establishment of a fenced, nondisturbance buffer until the young have reached independence (i.e., are flying and feeding on their own) as determined by a qualified biologist. The size of the buffer zone shall be determined by a qualified biologist at the time of the surveys. If the qualified biologist finds evidence of roosting bats but not a maternity site with young, then a plan shall be developed for removal and exclusion, in conjunction with the CDFW. The biologist shall provide the Town with a report detailing the results of the survey and any recommendations, as Prior to Tree
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Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
ATHERTON HOUSING ELEMENT UPDATE
MITIGATION MONITORING AND REPORTING PROGRAM
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warranted, required for establishment of protective buffers for bat roosts, if identified.
CULTURAL RESOURCES
CUL-1: Upon submittal of site-specific development proposals for housing opportunity sites identified in the 2023 – 2031 Housing Element, a projectspecific archaeological study should be undertaken for each development project proposed within the Subject Properties. An archaeological study should consist of a record search at the NWIC/CHRIS, a literature review, a pedestrian field survey, a site-specific assessment of the potential for subsurface archaeological resources to be present, and preparation of a report with project-specific recommendations. A geophysical survey and/or subsurface testing should be required for properties that have a high potential for buried archaeological resources, including Property V2, which is adjacent to the previously recorded Native American archaeological resource P-41-000278. Prior to Approval Project
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CUL-2 If an archaeological deposit is encountered during ground-disturbing activities, all work within 50 feet of the discovery shall be redirected until a Secretary of Interior-qualified Archaeologist assesses the find, consults with agencies and Native American tribes as appropriate, and makes recommendations for the treatment of the discovery. If avoidance of the archaeological deposit is not feasible, the archaeological deposit shall be evaluated for its eligibility for listing in the CRHR or as a unique archaeological resource. If the deposit is found to be eligible, all efforts should be made to avoid impacts to the resource. If avoidance is not feasible, adverse impacts shall be mitigated. Mitigation may include excavation of the archaeological deposit in accordance with the Secretary of Interior’s Standards and Guidelines for Archaeological Documentation that may include data recovery using standard archaeological field methods and procedures; laboratory and technical analyses of recovered archaeological materials; preparation of a report detailing the During
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Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
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methods, findings, and significance of the archaeological site and associated materials; and accessioning of archaeological materials and a technical data recovery report at a curation facility. Upon completion of the assessment, the archaeologist shall prepare a report to document the methods and results of the assessment. The report shall be submitted to the NWIC/CHRIS upon completion of the resource assessment.
CUL-3 In the event that human skeletal remains are uncovered during grounddisturbing activities, all work shall immediately halt and the San Mateo County Coroner shall be contacted to evaluate the remains and following the procedures and protocols pursuant to Section 15064.5 (e)(1) of the CEQA Guidelines. If the County Coroner determines that the remains are Native American, the Coroner shall contact the NAHC, pursuant to subdivision (c) of Section 7050.5 of the Health and Safety Code, and all excavation activities shall cease within a 50-foot radius of the find until appropriate arrangements are made. A Secretary of Interior-qualified Archaeologist should also evaluate the historical significance of the discovery, the potential for additional human remains to be present, and provide further recommendations for treatment of the resource in accordance with the MLD recommendations and the Secretary of Interior Standards for the Treatment of Historic Properties. Adherence to CUL-3 would ensure that development carried out under the proposed Project would have a less than significant impact from potential disturbance of human remains, specifically those interred outside of formal cemeteries. During
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GREENHOUSE GAS EMMISSIONS
GHG-1 If the Town has not adopted a GHG reduction strategy that is consistent with current State goals or that meets the criteria under State CEQA Guidelines Section 15183.5(b), then Town shall take the following actions:
1. Require all new or remodeled housing to include all-electric appliances and electric plumbing, in addition to any natural gas infrastructure. Building Permit Plan
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Housing Element 2023-2031 Update
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2. Require all new housing to include electric vehicle charging infrastructure that meets or exceeds current Building Code CALGreen Tier 2 compliance.
3. Implement the VMT Mitigation measure for proposed projects in the “highVMT area” that do not meet other screening requirements (i.e., generate less than 110 trips per day or located within a high-quality transit corridor).
The TDM measure is described in the Atherton HEU Transportation Analysis, prepared by Hexagon, dated February 13, 2024.
NOISE
NOI-1: The following best management practices shall be implemented to reduce noise from construction activities near sensitive receptors:
Pursuant to Municipal Code, restrict noise generating activities at the construction site or in areas adjacent to the construction site to the hours between 8:00 a.m. and 5:00 p.m., Monday through Friday and prohibit construction activities on Saturday, and Sunday and State, Federal or Local Holidays.
Consider temporary noise barriers during construction phases involving earth moving equipment (e.g. grading operations) where they would be effective in reducing the construction noise impact, when directly adjoining sensitive receptors.
Utilize ‘quiet’ models of air compressors and other stationary noise sources where technology exists.
Equip all internal combustion engine-driven equipment with mufflers that are in good condition and appropriate for the equipment. Locate all stationary noise-generating equipment such as air compressors and portable power generators as far away from adjacent receptors. Acoustically shield stationary equipment located near adjacent receptors with temporary noise barriers.
Locate staging areas and construction material as far away as possible from adjacent receptors.
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Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
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MITIGATION MONITORING AND REPORTING PROGRAM
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Prohibit all unnecessary idling of internal combustion engines. Route all construction traffic to and from the project site via designated truck routes and prohibit construction related heavy truck traffic in residential areas where feasible.
Control noise from construction workers’ radios to the point where they are not audible at existing residences that border the project site. Notify all adjacent receptors of the construction schedule in writing. Designate a “disturbance coordinator” who will be responsible for responding to any local complaints about construction noise. The disturbance coordinator will determine the cause of the noise complaint (e.g., starting too early, bad muffler, etc.) and will require that reasonable measures warranted to correct the problem be implemented. Conspicuously post a telephone number for the disturbance coordinator at the construction site and include it in the notice sent to neighbors regarding the construction.
Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
ATHERTON HOUSING ELEMENT UPDATE
MITIGATION MONITORING AND REPORTING PROGRAM
MITIGATION MEASURE IMPLEMENTATION RESPONSIBLE
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NOI-2: Prior to the approval of site-specific development of housing on properties with the RM-10, RM-20 and RM-40 overlay zones and identified in the 2023 – 2031 Housing Element, groundborne vibration shall be prepared by qualified professionals in accordance with industry-accepted methodology where heavy construction activities involving significant site grading, underground, or foundation work will occur within 25 feet of residential or other vibration sensitive uses. The industry-accepted methodologies include the recommended vibration assessment procedure and thresholds provided by public agencies such as Caltrans or the Federal Highway Administration. The studies should identify necessary construction vibration controls to reduce both human annoyance and the possibility of cosmetic damage. Controls shall include, but not be limited to, the following measures:
A list of all heavy construction equipment to be used for this project known to produce high vibration levels (tracked vehicles, vibratory compaction, jackhammers, hoe rams, etc.) shall be submitted to the Town by the contractor. This list shall be used to identify equipment and activities that would potentially generate substantial vibration and to define the level of effort for reducing vibration levels below the thresholds. Place operating equipment on the construction site as far as possible from vibration-sensitive receptors.
Use smaller equipment to minimize vibration levels below the limits. Avoid using vibratory rollers and tampers near sensitive areas. Select demolition methods not involving impact tools. Modify/design or identify alternative construction methods to reduce vibration levels below the limits.
Avoid dropping heavy objects or materials.
Prior to Approval Project
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Housing Element 2023-2031 Update
Town of Atherton Draft Mitigation Monitoring and Reporting Program
TRANSPORATION AND CIRCULATION
TRAN-1. Submittals of site-specific development proposals for housing sites identified in the 2023 – 2031 Housing Element that are located in a high-VMT area shall include a VMT analysis that identifies travel demand management (TDM) measures and/or physical measures (i.e. Tier 1 through Tier 4 strategies) to reduce VMT impacts to less than significant. Additional measures may be proposed by individual projects and/or required by Town staff to achieve the necessary VMT reductions or to meet applicable TDM reduction requirements. programs.
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TRIBAL CULTURAL RESOURCES
TCUL-1: Implement Mitigation Measure CUL-2. During
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