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HomeMy WebLinkAboutOMP_Water_Capture_AddendumADDENDUM TO THE ADOPTED FINAL INITIAL STUDY/MITIGATED NEGATIVE DECLARATION FOR THE ORANGE MEMORIAL PARK WATER CAPTURE PROJECT JULY 2020 1.0 INTRODUCTION This document is an Addendum to the Final Initial Study/Mitigated Negative Declaration (IS/MND) prepared for the Orange Memorial Park Water Capture Project (Project) (State Clearinghouse No. 20190609092). This Addendum assesses the environmental impacts associated with the implementation of the Project as required by the California Environmental Quality Act (CEQA) (California Public Resources Code [PCR] 21000 et seq.) and in compliance with the State CEQA guidelines (14 California Code of Regulations [CCR] 15000 et seq.). Since the adoption of the Final IS/MND, minor clarifications to the proposed Project have been proposed, thus requiring further environmental analysis. The Final IS/MND was adopted by the City of South San Francisco Public Works Director on August 21, 2019. The Addendum is intended to update the existing CEQA documentation to address minor technical revisions to the original Project description. Based on the updated environmental analysis in this Addendum, the proposed Project would not result in new significant impacts or mitigation measures, nor substantially increase the severity of the previously disclosed impacts identified in the adopted Final IS/MND. As a result, an Addendum is the appropriate CEQA document to address the minor technical revisions. 2.0 ADDENDUM REQUIREMENTS The Addendum has been prepared in accordance with the provisions of CEQA and the State CEQA Guidelines as implemented by the City of South San Francisco. According to Section 15164(b) of the State CEQA Guidelines, an Addendum to a Negative Declaration (ND) is the appropriate environmental document in instances when “only minor technical changes or additions are necessary or none of the conditions described in Section 15162 calling for the preparation of a Subsequent Negative Declaration have occurred.” Section 15162(a) of the State CEQA Guidelines states that no Subsequent ND shall be prepared for a project unless the lead agency determines, on the basis of substantial evidence in the light of the whole record, one or more of the following: 1) Substantial changes are proposed in the project which will require major revisions of the previous Environmental Impact Report (EIR) or ND due to the involvement of new significant environmental effects or a substantial increase in the severity of previously identified significant effects; 2) Substantial changes occur with respect to the circumstances under which the project is undertaken which will require major revisions of the previous EIR or ND due to the involvement of new significant environmental effects or a substantial increase in the severity of previously identified significant effects; or DocuSign Envelope ID: 9022A969-B29D-4A50-A2A2-7B9E54EE069B ADDENDUM City of South San Francisco Orange Memorial Park Water Capture Project July 2020 2 IS/MND Addendum 3) New information of substantial importance, which was not known and could not have been known with the exercise of reasonable diligence at the time the previous EIR or ND was adopted, shows any of the following: a. The project will have one or more significant effects not discussed in the previous EIR or ND; b. Significant effects previously examined will be substantially more severe than shown in the previous EIR or ND; c. Mitigation measures or alternatives previously found not to be feasible would in fact be feasible, and would substantially reduce one or more significant effects of the project, but the project proponents decline to adopt the mitigation measure or alternative; or d. Mitigation measures or alternatives which are considerably different from those analyzed in the previous EIR or ND would substantially reduce one or more significant effects on the environment, but the project proponents decline to adopt the mitigation measure or alternative. With respect to the proposed Project, the minor technical changes do not result in any new significant environmental impacts; therefore, the updated Project does not require an EIR. This Addendum does not require circulation because it does not provide significant new information that changes the adopted Final IS/MND in a way that deprives the public of a meaningful opportunity to comment on a substantial adverse environmental impact of the proposed Project or a feasible way to mitigate or avoid such an impact. This Addendum includes this introduction and a description of the updated and minor technical revisions associated with the proposed Project as they relate to the original proposed Project. The City shall consider this Addendum with the adopted Final IS/MND as part of the approval of the amended Project. The CEQA documentation for this Project, including this Addendum and the adopted Final IS/MND, is available for review at the City of South San Francisco, 315 Maple Avenue, South San Francisco, CA 94083. It is also available online at the City’s website at: http://www.ssf.net/ceqadocuments. 3.0 PREVIOUS CEQA DOCUMENTATION A Public Review Draft IS/MND was prepared for the Orange Memorial Park Water Capture Project and circulated for public and agency review from June 21, 2019 to July 22, 2019. The Final IS/MND was adopted by the City of South San Francisco Public Works Director on August 21, 2019. A Notice of Determination (NOD) was filed with the San Mateo County Clerk and State Clearinghouse on August 21, 2019. There were no legal challenges to the adequacy of the Final IS/MND during the 30-day statute of limitations associated with the NOD, pursuant to CEQA (PRC Section 21167 and CEQA Guidelines Section 15094). 4.0 WHY AN ADDEDNUM IS APPROPRIATE CEQA Guidelines Section 15162 and 15164 sets forth criteria to assess which environmental document is appropriate. Since the adoption of the Final IS/MND and the decision to proceed with the proposed Project by the City of South San Francisco Public DocuSign Envelope ID: 9022A969-B29D-4A50-A2A2-7B9E54EE069B ADDENDUM Orange Memorial Park Water Capture Project City of South San Francisco IS/MND Addendum 3 July 2020 Works Director on August 21, 2019, one minor technical change to the project design has occurred related to the diversion rate associated with the water capture and treatment facility. This document is an Addendum to the Final IS/MND to describe the updated and minor technical revisions in response to a request from the San Francisco Bay Regional Water Quality Control Board (RWQCB), so that the Final IS/MND, with the updated and minor technical revisions, may be used by the San Francisco Bay RWQCB for purposes of environmental review and issuance of the proposed Project’s Section 401 Water Quality Certification under the Clean Water Act (CWA) (Corps File No. 2019-00181S; Place ID 862602, Effective April 21, 2020). This Addendum also incorporates the additional analysis for inclusion in the City’s environmental record. The updated analysis does not substantially change the findings and conclusions of the Final IS/MND and a Subsequent IS/MND is not necessary pursuant to Section 15162 of the State CEQA Guidelines. 5.0 UPDATED PROJECT DESCRIPTION Original Project Description Summary The proposed Project would provide water quality improvements to meet National Pollutant Discharge and Elimination System (NPDES) requirements of the San Francisco Bay Municipal Regional Stormwater Permit (MRP). Section 402 of the federal CWA, as amended by the Water Quality Act of 1987, requires NPDES permits for stormwater discharges from municipal separate storm water systems (MS4s), stormwater discharges associated with industrial activity (including construction activities), and designated stormwater discharges, which are considered significant contributors of pollutants to waters of the United States. The MRP governs stormwater discharges to San Francisco Bay from the City of South San Francisco and 21 other co-permittees in San Mateo County. The proposed Project is designed to reduce pollutant discharges of polychlorinated biphenyls (PCBs) and mercury to San Francisco Bay to comply with Total Maximum Daily Load (TMDL) requirements, as well as trash discharge reductions under the MRP requirements. The proposed Project would include construction and operation of a water capture and treatment facility through the installation of a drop inlet diversion channel and a pretreatment structure (trash screen and sediment removal chamber) in the upper and western end of the Colma Creek flood control channel and Orange Memorial Park (Park) boundary. Flows from the Colma Creek flood control channel would be diverted into a drop inlet that would route flows into a pretreatment structure (trash screen, baffle, and sediment removal chamber) that would remove trash, gross solids, and debris and sediment 100 microns and larger in size. Pretreated water would then enter into a diversion pipe leading to an underground stormwater storage reservoir in the southeastern corner of the Park. A portion of the storage would function as a cistern holding water for eventual non-potable irrigation use in and around the Park, and the remainder would function as an infiltration chamber. These storage facilities would be constructed underneath a portion of the Park’s two existing ballfields. When storage capacity is exceeded, treated overflow would be discharged back into Colma Creek. This regional Project would have multiple benefits in addition to water quality improvements, including localized flood reduction, potable offset via reuse for irrigation, and recharging groundwater via infiltration. The proposed Project is estimated to capture and treat 16 DocuSign Envelope ID: 9022A969-B29D-4A50-A2A2-7B9E54EE069B ADDENDUM City of South San Francisco Orange Memorial Park Water Capture Project July 2020 4 IS/MND Addendum percent of the average annual drainage from approximately 6,500 acres of land mostly in the City of South San Francisco, Town of Colma, the City of Daly City, and unincorporated San Mateo County; less than one percent of the drainage area is in the cities of Pacifica and San Bruno. The adopted Final IS/MND evaluated the environmental impacts associated with two cistern and infiltration chamber storage systems: 1) a 4 acre-feet cistern and infiltration chamber storage system with a 1.2-acre footprint; 2) and a 7.5 acre-feet cistern and infiltration chamber storage system with a maximum 2.5-acre footprint. The 4 acre-feet system would be designed to provide treatment to an estimated 320 acre-feet of stormwater runoff. The 7.5 acre-feet system would be designed to provide treatment to an estimated 650 acre-feet of stormwater runoff. Installation of the drop inlet, pretreatment structure, and diversion pipe within Colma Creek and near an open picnic area in the western portion of the Park would involve excavation and trenching that would last approximately one month. Excavation and installation of the underground storage reservoir would require the temporary closure of the two ballfields for 9 to 12 months. During construction, the two ballfields would be secured with construction fencing and closed to the public. Construction of the entire proposed Project is anticipated to last 12 to 18 months. Following construction of the proposed Project, the open picnic areas would be graded and re-landscaped. The two ballfields would be brought up to grade in preparation for a separate and subsequent ballfields improvement project to be completed by the City of South San Francisco Parks & Recreation Department. Ballfield improvements would include the installation of new dugouts, bleachers, lighting, and a scoreboard. These improvements are separate from the proposed Project and are outlined in the Orange Memorial Park Sports Field Renovation project summarized in the City’s 2018-2019 Capital Improvement Program. Updated Project Description Summary The updated Project description includes minor technical revisions associated with how much annual stormwater would be diverted from the Colma Creek flood control channel into the proposed water capture and treatment facility during a typical year. The proposed Project would divert up to 30 cubic feet per second of water flows from the Colma Creek flood control channel, or approximately 16 percent of the average annual flows in the flood control channel at the Project site during a typical year. All diverted flows would be captured in a drop inlet diversion channel, treated by a pretreatment structure with a trash screen and sediment removal chamber, and then transferred via a 36-inch diversion pipe to a flow splitter and an underground cistern and infiltration system. Figure 1 summarizes the project hydrology within Colma Creek on a watershed basis. Of the 16 percent annual water flows diverted, 7 percent would reach the underground storage cistern, where 6 percent would infiltrate and recharge the groundwater table, and 1 percent would be further treated and used for non-potable irrigation use in the Park. After pretreatment, the other 9 percent would overflow back to the Colma Creek flood control channel via a 36-inch outfall pipe. DocuSign Envelope ID: 9022A969-B29D-4A50-A2A2-7B9E54EE069B ADDENDUM Orange Memorial Park Water Capture Project City of South San Francisco IS/MND Addendum 5 July 2020 The updated Project involves the construction of a 5.4 acre-feet cistern and infiltration chamber storage system that includes an approximate 1.1-acre footprint, which is within the larger 2.5-acre footprint originally evaluated in the adopted IS/MND. Once operational, the water capture and treatment facility would treat an estimated 640 acre-feet of stormwater runoff. Construction duration is anticipated to be similar to the time frame summarized in the adopted IS/MND. The installation of the grit chamber and trash screen facility (i.e., pretreatment structure) near the open picnic area would involve excavation that is now estimated to occur over a two to three month period versus a one month period. Construction of the entire proposed Project is still anticipated to last up to 18 months, as summarized in the adopted IS/MND. 6.0 UPDATED ENVIRONMENTAL ANALYSIS This section addresses updates to the impact analysis in the Draft IS/MND as a result of the project changes described above. Initial Study Checklist Section IV, Biological Resources, was updated to address the increased diversion rate associated with the proposed Project water capture and treatment facility and the related downstream impacts to biological resources. Section X, Hydrology and Water Quality, was updated to address the increased diversion rate and potential impacts on existing drainage patterns and beneficial impacts associated with increased groundwater recharge and reduced localized flooding. The minor technical revisions associated with the diversion rate for the proposed Project does not result in any new significant impacts, nor does it substantially increase the severity of previously disclosed impacts for other environmental resources (hazardous materials, etc.) identified in the adopted Final IS/MND. This Addendum discusses only those impacts that have the potential to be affected by the minor technical revisions. BIOLOGICAL RESOURCES As described in the IS/MND the proposed Project would result in less than significant impacts on riparian habitat and other sensitive natural communities identified in local or regional plans, policies, or regulations. The proposed Project would also result in a less than significant impact on the movement of native resident or migratory fish or wildlife species, and with established migratory wildlife corridors. The minor technical revisions Figure 1. The proposed Project would divert 16 percent of the annual water flows from the Colma Creek flood control channel during a typical year. Of the 16 percent annual water flows diverted and treated, 9 percent would overflow back to Colma Creek, 6 percent would infiltrate and recharge the groundwater table, and 1 percent would be polished and disinfected to meet irrigation demands in and around the Park. DocuSign Envelope ID: 9022A969-B29D-4A50-A2A2-7B9E54EE069B ADDENDUM City of South San Francisco Orange Memorial Park Water Capture Project July 2020 6 IS/MND Addendum associated with the amount of water that will be diverted, captured, and treated by the proposed Project was not fully described in the adopted Final IS/MND and is described and evaluated further below. The proposed Project would occur within and adjacent to Colma Creek, a perennial stream that has been identified as a non-tidal water of the United States that flows into tidal waters of the United States. The drainage channel has been previously modified for flood control management and the area adjacent to the Colma Creek does not support riparian habitat. The bottom and sides of the 35 to 40-foot channel are entirely lined with concrete and the majority of the adjacent upland vegetation consists of eucalyptus woodland and ornamental trees. Riparian vegetation was only observed growing on accumulated sediment within the flood control channel during dry months; however, this vegetation was not observed in the wet months. No local or regional sensitive habitat types, natural communities, or sensitive plant species regulated by the U.S. Fish and Wildlife Service or California Department of Fish and Wildlife are present within the Project site. Urban recreational development within the Park has removed much of the suitable habitat for sensitive plant species. The proposed Project would involve installing a drop inlet diversion channel structure within the bottom of the concrete channel, but would not impact any adjacent riparian habitat. The proposed Project would divert and treat approximately 16 percent of annual water flows within the Colma Creek flood control channel during a typical year. Of this total amount of diverted annual water flows approximately 7 percent would remain in the underground cistern for groundwater recharge and non-potable irrigation use in and around the Park. This amount of diverted water flows would not substantially alter the downstream water flows within Colma Creek, nor riparian habitat or downstream sensitive fish or bird species (i.e., Green Sturgeon, California Ridgeway’s Rail) within the tidal salt and brackish marshes in San Francisco Bay. While a portion of the treated flows would be used for irrigation in the Park and stored within the underground cistern, this portion is limited to 1 percent of the total stormwater flows captured with the proposed Project. The vast majority of the diverted water would be treated, infiltrated back into the groundwater table, or discharged back to Colma Creek via a 36-inch overflow and outfall pipe. Depending on seasonal water table variations during the year, the water infiltrated to the groundwater table via the water capture and treatment facility would eventually flow towards the San Francisco Bay, and the downstream segment of Colma Creek within the tidal marsh would receive base flow from the groundwater inflow. The downstream segments of Colma Creek past the Park would receive additional sources of stormwater runoff from the drainage area of the larger Colma Creek watershed before its discharge into the San Francisco Bay. The segments of Colma Creek past U.S. Highway 101 (half-mile from Park) are also influenced by tidal fluctuations in the San Francisco Bay. Consequently, the proposed Project would not have a substantial adverse impact on riparian or salt marsh habitats as identified by regulatory agencies, nor on downstream riparian or salt marsh habitats within the tidally-influenced portion of Colma Creek. While the San Francisco Bay supports native fish such as steelhead, coho salmon, green sturgeon, and longfin smelt, the Colma creek flood control channel adjacent to the Project site does not provide suitable habitat for native fisheries given the lack of vegetation and bottom substrate. Previous studies for downstream reaches of Colma Creek found the area DocuSign Envelope ID: 9022A969-B29D-4A50-A2A2-7B9E54EE069B ADDENDUM Orange Memorial Park Water Capture Project City of South San Francisco IS/MND Addendum 7 July 2020 generally unsuitable for sensitive fish populations (Horizon Water and Environment 2015a; 2015b). While the proposed Project involves the diversion of approximately 16 percent of the annual water flows along the Colma Creek flood control channel, most of these flows consist of stormwater flows and only 7 percent of these flows would be diverted and remain in underground storage for groundwater recharge and non-potable irrigation use in the Park. Approximately 9 percent of the treated stormwater would infiltrate back into the groundwater table or be discharged back to Colma Creek via one 36- inch overflow and outfall pipe. Therefore, the proposed Project would not interfere with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors. Impacts on biological resources related to wildlife movement would be less than significant. Taking into account the minor technical revisions related to the diversion rate, impacts to riparian habitat, sensitive natural communities, and migratory wildlife corridors would remain less than significant. The minor technical revisions does not change the analysis or the conclusions in the adopted IS/MND pertaining to biological resources. HYDROLOGY AND WATER QUALITY As described in the IS/MND, the proposed Project would result in less than significant impacts on existing drainage patterns in the Park, and a less than significant impact on the implementation of a water quality control plan or sustainable groundwater management plan. The minor technical revisions associated with the amount of water that will be diverted would result in net beneficial impacts associated with improved groundwater recharge, reduced localized flooding, and improved and treated receiving water quality in the San Francisco Bay. The minor technical revisions associated with the amount of water that will be diverted, captured, and treated by the proposed Project was not fully described in the adopted Final IS/MND and is described and evaluated further below. The proposed Project as a water capture facility would not entail any development or construction that would alter current drainage patterns at the Project site or in the Park. The proposed Project would involve the installation of an instream drop inlet diversion channel within the Colma Creek flood control channel. This structure and the modifications to bottom of the concrete channel (i.e. ramp cuts to divert water flows) would not measure more than 0.012 acres (520 square feet). The proposed Project would also include the installation one 36-inch overflow and outfall pipe that measures 0.0002 acres (7 square feet). While the water capture facility would redirect and treat stormwater runoff within the underground reservoir cistern and infiltration chamber, the local drainage pattern would remain the same as it exists today. The proposed water capture and treatment facility would divert 16 percent of the water flows from Colma Creek through the facility within the southern portion of the Park and approximately 9 percent of the treated water would be diverted back to the Colma Creek flood control channel via the overflow and outfall pipe situated roughly 800 feet downstream of the instream drop inlet diversion channel. Proposed construction would not cause substantial erosion or siltation. The San Francisco Bay RWQCB has developed TMDLs for several pollutants originating from urban and stormwater runoff in the watersheds throughout San Mateo County. Colma Creek is among the impaired water bodies with TMDLs for PCBs, mercury, and trash reductions and has been identified for water quality improvements in the MRP and DocuSign Envelope ID: 9022A969-B29D-4A50-A2A2-7B9E54EE069B ADDENDUM City of South San Francisco Orange Memorial Park Water Capture Project July 2020 8 IS/MND Addendum San Mateo County Stormwater Resources Plan. The proposed Project co-locates stormwater diversion and treatment facilities in the Park to meet the NPDES requirements of the San Francisco Bay MRP. Implementation of the proposed Project would address multiple water quality targets, including a reduction in pollutant discharges of PCBs and mercury to San Francisco Bay to comply with TMDL requirements, as well as trash discharge reductions. For these reasons, the proposed Project with the minor technical revisions associated with the stormwater diversion rate would not conflict or obstruct the implementation of a water quality control plan or sustainable groundwater management plan. The proposed Project would reduce localized flooding, result in net benefits to downstream stormwater runoff and receiving water quality in the San Francisco Bay, and groundwater recharge in the West Side Ground Water Basin. Therefore, taking into account the revised project information related to the diversion rate, impacts to hydrology and water quality, including impacts to drainage patterns and conformance to existing water quality plans would remain less than significant. The revised project information does not change the analysis or the conclusions in the adopted IS/MND pertaining to hydrology and water quality. 6.0 DETERMINATION In accordance with Section 15164 of the State CEQA Guidelines, the City of South San Francisco has determined that this Addendum to the adopted Final IS/MND is necessary to document the minor technical revisions that have occurred in the proposed Project description for the Orange Memorial Park Water Capture Project since the adoption of the Final IS/MND. The City has reviewed and considered the information contained in this Addendum and finds that the preparation of a Subsequent CEQA document that would require public circulation is not necessary. Any substantial changes in the proposed Project may be subject to further environmental review. Signature Date Eunejune Kim City Engineer/Public Works Director Printed Name Title City of South San Francisco Agency DocuSign Envelope ID: 9022A969-B29D-4A50-A2A2-7B9E54EE069B 8/13/2020 ADDENDUM Orange Memorial Park Water Capture Project City of South San Francisco IS/MND Addendum 9 July 2020 7.0 SUPPORTING CEQA DOCUMENTATION A. Orange Memorial Park Water Capture Project Final Mitigated Negative Declaration (State Clearinghouse No. 20190609092). Adopted August 21, 2019. 8.0 REFERENCES Horizon Water and Environment. 2015a. Biological Assessment for the Colma Creek Flood Control Channel Maintenance Project. San Mateo County, California. December 2015. Accessed on 28 April 2019. Retrieved from: https://publicworks.smcgov.org/sites/publicworks.smcgov.org/files/ColmaCreekFl oodControlChannelMaintenance_ISMND_June2016_0.pdf Wetland Delineation Report for the Colma Creek Flood Control Channel Maintenance Project. 2015b. San Mateo County, California. December 2015. Accessed on 28 April 2019. Retrieved from: https://publicworks.smcgov.org/sites/publicworks.smcgov.org/files/ColmaCreekFl oodControlChannelMaintenance_ISMND_June2016_0.pdf DocuSign Envelope ID: 9022A969-B29D-4A50-A2A2-7B9E54EE069B