Former Reeves Rubber, Inc., Interim Remedial Measures Workplan

Former Reeves Rubber, Inc., Interim Remedial Measures Workplan

The California Department of Toxic Substances Control approved an Interim Remedial Measures Workplan that describes interim remedial actions to be completed at the Pico Pavilion Shopping Center located at 415 Avenida Pico in the City of San Clemente. Remedial actions include installation and operation of a soil vapor extraction system to address soil vapor impacts. Background: The Site covers approximately 2.7 acres and is located in a commercial/industrial area of the city. The Pico Pavilion Shopping Center has occupied the Site since 1989 and encompasses three single-story buildings (A, B, and C), 18 sub-tenant units (Units A through Unit P), and a central parking lot. The Site was formerly occupied by the Reeves Rubber Facility from the 1940s through the 1980s. Previous operations at the Former Reeves Rubber Facility included manufacturing for automotive and aerospace industries. Based on environmental investigations dating back to 1994, tetrachloroethene (PCE) and trichloroethene (TCE) have been identified as chemicals of concern (COCs) in soil, groundwater, soil vapor, and indoor air at the Site. Saint-Gobain entered into a Voluntary Cleanup Agreement (VCA) with DTSC to investigate and remediate the Site on March 13, 2019 (Docket Number HSA- FY18/19-045). Previous Investigations: A series of environmental investigation activities conducted at the Site revealed the presence of elevated concentrations of the COCs identified above. An Additional Site Assessment and Sub-Slab Depressurization Pilot Test Report (dated 2021) reviewed historical data, summarized results of a passive soil vapor survey, and identified three potential areas of concern (AOCs) (Areas 1 through 3) as described below: Area 1: Located east of and underlying the western portion of Building A, with highest concentrations adjacent to the former machine shop, the former concrete waste disposal pits, and former dry-cleaning operations. Area 2: Located south of and underlying the northern portion of Building B, downgradient from a former solvent storage area. Area 3: Located west of Building C, adjacent to a former stock preparations building. It is noted that additional investigation is ongoing to further delineate the extent of COCs upgradient and downgradient of the Site and to aid in the correlation between specific sources or releases to the presence and distribution of contaminants in the AOCs. There are several nearby and upgradient properties with documented releases or a history of operations consistent with the Site-related COCs. A Site Assessment (SA) and Sub-Slab Depressurization System (SSDS) Report (dated 2023) summarized the soil, groundwater, and soil vapor sampling conducted from January through August 2022 to further delineate the extent of Siterelated COCs in the AOCs. A Supplemental SA Report and Supplemental SA Addendum (dated 2024 and 2025, respectively) summarized a Membrane Interface Hydraulic Profiling (MIHPT) investigation, and findings from onsite and offsite investigative locations. A screening-level human health risk evaluation (SLHHRE) Report (dated 2024) evaluated potential human exposures to COCs in onsite soil, soil vapor, shallow groundwater, and indoor air. The SSDS began operating at the Site (beneath Building A) in September 2022 to recover and treat soil vapors potentially impacted with volatile organic compounds (VOCs) beneath the building. The SSDS consists of suction points distributed throughout Building A; sub-slab vapor pins to monitor vacuum response; and, the SSDS blower, ancillary equipment, and instrumentation located in Unit K of Building A. Extracted vapors pass through an air/water separator vessel (“knockouttank”), cool down by an air-to-air heat exchanger, and then are treated by two vapor-phase granularly activated carbon vessels connected in series. The SSDS operates under a South Coast Air Quality Management District (SCAQMD) air permit (Permit No. G73007). Between October and November 2024, a Soil Vapor Extraction (SVE) pilot study was conducted to evaluate the effectiveness of a SVE system to reduce the concentrations and residual mass of VOCs in the vadose zone and to identify design parameters for a full-scale SVE system to be implemented as an interim remedial measure (IRM). A horizontal SVE well (SVE-1H) and two vertical SVE wells (SVE-2S/M) were installed for the SVE pilot study. SVE-1H was constructed starting with an entry point in the parking lot in front of Building A with a 100-foot-long custom-slotted well screen extending beneath Building B. SVE-2S and SVE-2M were installed in a single 12-inch borehole using 2-inch-diameter, Schedule 40 polyvinyl chloride (PVC) slotted screens. SVE-2S is screened from 7 to 15 feet below ground surface (bgs) and SVE-2M is screened from 22 to 30 feet bgs. The SVE pilot study demonstrated that SVE is an effective remedial technology to extract and capture potentially impacted soil vapor and reduce contaminant mass in the vadose zone at the Site and is an appropriate remedial alternative for consideration for full-scale implementation at the Site. The results of the SVE pilot study were used to develop the conceptual SVE design to be used in the full-scale system described in the IRM Workplan. Project Activities: The interim remedial action will involve installing and operating the SVE system to address VOCs in soil and soil vapor in the three AOCs. The SVE system will be installed in Unit K (Building A) where the existing SSDS is currently located. The SVE system will utilize the existing horizontal well (SVE-1H), existing nested vertical wells (SVE-2S/M), and five new nested vertical wells (SVE-3S/M through SVE-7S/M). The five new nested vertical wells will be spaced approximately 130 feet apart and will have similar screen intervals as wells SVE-2S and SVE-2M. Final screen depths for the five new nested vertical wells will be adjusted based on field observations during drilling, such as soil lithology, photoionization detector readings, and groundwater depth. The SVE wells will be connected to a SVE blower skid using a network of aboveground and belowground PVC or high-density polyethylene piping. The SVE conveyance piping trenches will be lined with fine bedding sand to at least 6 inches over the top of the piping. The trenches will be backfilled with the soil excavated from the trench or new clean imported soil to within 12 inches of the existing grade. A single 6 to 8-inch-thick layer of aggregate base will then be placed and compacted, and the trenches will be resurfaced with 4 inches of asphalt to match existing conditions. Excess trench spoils not used for backfilling will be temporarily stockpiled onsite pending waste characterization and arrangements for disposal offsite. Upon approval of the waste profile, the waste will be transported by a licensed waste transporter and disposed of in accordance with local, state, and federal regulations. The blower will be similar to the existing SSDS blower currently operating at the Site. Extracted vapors will be routed through a moisture knockout tank, followed by two vapor-phase granularly activated carbon vessels arranged in series to remove VOCs before discharge to the atmosphere. The extracted vapors will be managed in accordance with a South Coast Air Quality Management District (SCAQMD) air permit, which will be obtained to operate the SVE blower and off-gas treatment system. Condensate from the moisture knockout tank will be pumped to a holding tank for temporary storage prior to disposal offsite. Drilling and building permits will be obtained from the City of San Clemente for the installation of the SVE system and wells. All SVE well locations will be advanced within the boundaries of the Site. Construction of the SVE system will be performed in accordance with the DTSC-approved IRM Workplan. A Site-specific health and safety plan (HASP) has been previously prepared for the Site, and the existing HASP will be updated to address additional health and safety hazards associated with installation of the SVE system. The SVE system is proposed to operate continuously for three years followed by 2 years of intermittent operation and monitoring. 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.

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