Vineland Family Housing Removal Action Workplan

The project consists of implementing a Removal Action Workplan (RAW) to address concentrations of volatile organic compounds (VOCs) in soil and sub-slab vapor on a 2.18 acre parcel located at 8015 and 8025 Vineland Avenue in Los Angeles, California (“Site”). The RAW proposes implementation of a vapor intrusion mitigation system (VIMS) with passive sub-slab ventilation (SSV) beneath two buildings that are proposed for development at the Site, along with adoption of a Land Use Covenant (LUC). Background: The Site is located in the Sun Valley neighborhood of Los Angeles and is identified as Los Angeles County Assessor’s Parcel Number (APN) 2314-006-002. The Site is an “L-shaped” parcel, roughly bounded on the west and northwest by apartments and residential properties, on the south by Strathern Street, on the east by Vineland Avenue, and on the north and southeast by commercial properties. The Site is currently vacant except for the concrete building foundation of a former 20,181-square-foot building, historically used as a grocery/market, which was destroyed in a fire in July 2021. Additionally, a temporary building and storage containers associated with a recycling center are located off Strathern Street in the southwest portion of the Site. The remaining portions of the Site consist of asphalt-paved parking areas and driveways providing access from Strathern Street to the south and Vineland Avenue to the east. DTSC and Las Palmas Housing and Development Corporation entered into a Voluntary Cleanup Agreement (Docket Number HSA-FY21/22-115 signed on March 29, 2022) to address contaminants on the Site. The Site is planned to be redeveloped with mixed-used commercial and multi-family/senior residential uses. Redevelopment of the Site entails the construction of a 6-story mixed-use building on the eastern/central portion of the Site (Vineland Apartments), which would include 136 affordable apartment dwelling units, 26,056 square feet of ground-floor commercial space, and underground parking. Additional development on the western portion (Strathern Senior Apartments) includes a 5-story building consisting of 97 affordable senior housing units, common areas, and underground parking. Two single-story underground parking structures are proposed to a depth of 12 feet beneath the majority of the Site apart from the southern portion of the senior development. Vehicular access to the Site is proposed at Vineland Avenue via two separate driveways and Strathern Street via one driveway, with reciprocal access at the northern adjacent property. It is noted that the City of Los Angeles previously determined that each of the land use development projects with which the subject RAW is associated are statutorily exempt from CEQA as a ministerial action pursuant to Public Resources Code Section 21080(b)(1) and Los Angeles Municipal Code (“LAMC”) Section 12.22 A.31. The City issued SB 35 Letters of Compliance dated April 20, 2023, to the RP regarding the ministerial approvals. The subject site mitigation and cleanup activities set forth in the RAW are considered discretionary approvals subject to CEQA and are outside the scope of the activities determined to be statutorily exempt. Previous Investigations: Investigations at the Site indicate that the primary Chemicals of Potential Concern (COPCs) include PCE, benzene, ethylbenzene, chloroform, dichlorodifluoromethane, and 1,2-DCA, which were detected at concentrations exceeding applicable screening levels (SLs). Per information provided in the RAW, soil investigation results did not indicate any COPCs in soil exceeding SLs, or potential on-Site sources of the reported soil vapor impacts. Groundwater is estimated to be at a depth of greater than 300 feet below ground surface (bgs). Based on the soil sampling results, soil and/or groundwater does not appear to have been potentially impacted by historical operations at the Site. Project Activities: The activities outlined in the RAW consist of implementing a VIMS with passive SSV beneath the two proposed buildings. The SSV system is designed for soil vapor to be passively diverted into the venting system and safely discharged to the atmosphere by means of vertical vent risers terminating at the building roof line. The venting system will consist of a sub-slab gravel layer beneath the entire footprint of the building that contains low-profile, 1-inch sub-slab collection pipes, which will transition to 3-inch rigid polyvinyl chloride pipe where penetration though building footers occurs. The collection pipes will be connected to carbon steel vertical risers along the building exterior that terminate above the roof line. An impervious membrane barrier will be installed above the sub-slab passive venting system and beneath the entire extent of the building footprint. The horizontal membrane barrier will consist of a minimum cured thickness of 60 mil (0.06 inches) Liquid Boot Plus VI-20 geomembrane. Monitoring probes will be placed within the gravel layer (below the membrane) and terminate in monitoring vaults outside the building perimeter wall. Sub-slab soil vapor monitoring probes will be used to monitor soil vapor concentrations under the slab. The VIMS installation will be implemented as part of the same construction activities which have already been approved for development through the City of Los Angeles’s SB 35 streamlined environmental review process. Installation of the VIMS would not require any substantial changes to the timing or duration of site preparation and construction activities, the type of equipment utilized as part of site preparation and construction, or the number of workers involved or number of worker transportation trips for the site preparation and construction processes. VIMS installation will not require any changes to the site boundaries, building footprint, aesthetic design, or operational characteristics from what was previously evaluated. In addition, a Land Use Covenant (LUC) will be recorded with Los Angeles County to ensure notifications are made to DTSC prior to any future earthwork activities at the Site, prevent disturbance of the vapor barrier, and ensure the prohibition of any groundwater extraction. Although not anticipated, in the event biological, cultural or historical resources are discovered in the course of project activities, work will be suspended while a qualified biologist, cultural or historical specialist makes an assessment of the area and arrangements are made to protect or preserve any resources that are discovered. If human remains are discovered, no further disturbance will occur in the location where the remains are found, and the County Coroner will be notified pursuant to the Health and Safety Code, Chapter 2, Section 7050.5.