7-Eleven Store No. 13799 and Former Quick Quality Cleaners Removal Action Workplan

7-Eleven Store No. 13799 and Former Quick Quality Cleaners Removal Action Workplan

Project Description: The project consists of implementing the 7-Eleven Store No. 13799 and Former Quick Quality Cleaners Removal Action Workplan (RAW). The goal of the RAW is to address volatile organic compounds (VOCs) contamination in soil vapor on an approximately 0.6-acre commercial parcel located at 16791 and 16795 McFadden Avenue in the city of Tustin (Site). The project activities consist of the excavation and offsite disposal of approximately 1,210 cubic yards (CYs) of VOC-impacted soil along with potential installation and operation of a soil vapor extraction (SVE) system. Background: The Site is currently occupied by a 7-Eleven-branded convenience store. Adjacent to the eastern side of the existing building was a second suite that included a former dry-cleaning business and laundromat. The building was demolished in August 2023, and the footprint of the former building currently consists of bare dirt. The former dry-cleaning/laundromat suite and the 7-Eleven building are located in the central portion of the Site. The Site is part of an approved redevelopment project that entails demolition of the existing 7-Eleven-branded convenience store, construction of a replacement building on the east-adjacent vacant property, and the installation of fuel dispensing infrastructure across both properties (including an underground storage tank (UST) basin on the southern portion of the Site). The City of Tustin approved the project on December 22, 2020, and filed a Notice of Exemption (Class 32) dated February 2, 2021. In March 2021, 7-Eleven entered into a Standard Voluntary Agreement (Docket No. HSA-FY20/21-081) with the Department of Toxic Substances Control (DTSC), for the investigation and remediation of subsurface impacts at the Site. Previous Investigations: Historical Site investigation activities assessed Site soil, soil vapor, and groundwater for VOCs because of the former operation of a dry-cleaning facility at the Site. Limited soil assessment was also conducted to evaluate potential petroleum hydrocarbon and metals impacts. The RAW addresses VOCs previously identified in Site soils and VOCs (most notably tetrachloroethene (PCE)) likely present in Site soils based on observed vapor phase VOC concentrations. In February 2019, a Phase I Environmental Site Assessment (ESA) was completed for the Site. According to the ESA, Quick Quality Cleaners occupied an eastern tenant space of previous commercial building on the Site (16795 McFadden Avenue) from at least 1980 to 2014. Permits were issued to the facility in 1983 and 1998 for the operation of on-site dry-cleaning equipment that utilized PCE. In March 2019, as part of a Phase II ESA, four soil borings and four sub-slab soil vapor probes were advanced to analyze underlying soil. PCE was detected in all analyzed soil and soil vapor samples. All the detected PCE vapor concentrations in the sub-slab probes exceeded the DTSC screening levels (SL) and the San Francisco Bay Regional Water Quality Control Board’s (SFBRWQCB’s) Environmental Screening Level (ESL) for sub-slab commercial soil vapor. Between June and October 2020, two soil vapor extraction events occurred. Subsequently, soil vapor samples showed a rebound in vapor concentrations over time. On August 25, 2023, 7-Eleven removed the concrete slab at the former dry-cleaning suite in the area of the former dry-cleaning equipment. The demolition activities were conducted under the oversight of DTSC. Ambient air monitoring and field soil screening were conducted during demolition activities for chlorinated solvents. PCE vapors were not detected in the ambient air or in surface soil during removal activities. During May 2025, a 4-day SVE pilot test was conducted, during which a trailer-mounted SVE system was operated to extract vapors from existing SVE wells. Lastly, during May and June 2025, five triple-nested soil vapor probes were installed and sampled on the east-adjacent vacant property to evaluate soil vapor conditions in preparation for upcoming redevelopment of the property and the Site. PCE, the primary VOC of concern on the Site, was detected in soil vapor samples collected below the SL for indoor air in a commercial/industrial land use scenario. No other VOCs were detected at concentrations that exceeded their respective RSLs or (when established) SLs for indoor air in a commercial/industrial land use scenario. The RAW was prepared to facilitate remedial actions (i.e., soil excavation) at the Site during the redevelopment activities, associated post-excavation confirmation soil and soil vapor sampling activities, and subsequent remedial actions (potential installation and operation of an SVE) to be performed after Site redevelopment. Project Activities: Based on the proposed Site redevelopment activities, approximately 1,210 CY of potentially VOC-impacted soil will be excavated during the construction of the UST basin and transported offsite for disposal at an appropriately licensed facility. The proposed excavation area will be located inside the footprint of the proposed UST basin associated with Site redevelopment. Assuming trucks will be loaded to hold 18 CYs of soil, and the excavation and loading process results in a 50% increase in volume, it will take approximately 101 truckloads to remove the anticipated volume of waste soil from the Site over a period of approximately 6 weeks. Based on the observed concentrations of VOCs (particularly PCE) in soil vapor beneath the Site and the lack of delineation of vapor phase VOC concentrations, an SVE system may be installed and operated at the Site to remove vapor phase VOCs present in the subsurface and to limit potential off-site migration of vapor-phase VOCs. However, excavation of potentially VOC-impacted soil as proposed above may result in a localized reduction in observed vapor phase VOC impacts. Therefore, following completion of the proposed soil excavation activities and assessment of the west-adjacent property, soil vapor conditions will be reevaluated, and the need of further remediation will be confirmed. The RAW does not include design specifications for an SVE system that may be installed at the Site. If Site conditions are still found to warrant remediation following the soil excavation and western-adjacent property assessment, a remedial design package will be prepared for installation of an SVE system at the Site to mitigate potential vapor intrusion concerns associated with vapor phase VOCs present in soil across the Site. Based on currently available data, the conceptual design of the SVE system entails the installation of a network of SVE wells screened at multiple depth intervals. Based on the observed mass recovery rates during the recent SVE pilot testing, vapor abatement will likely involve the use of granulated activated carbon and a knock-out tank for capturing entrained moisture. The vacuum extraction blower sizing and associated electrical service requirements will be dictated by the designed network of vapor extraction wells. The activities described in this RAW are subject to South Coast Air Quality Management District (SCAQMD) Rule 1166 – Volatile Organic Compound Emissions from Decontamination of Soil. Because the quantity of potentially impacted soil to be disturbed (less than 2,000 CYs), a Various Locations Plan will be utilized in lieu of preparation of a Site-specific compliance plan to describe the measures and monitoring to be implemented to identify and limit potential emissions of VOCs from impacted soils. The project is also subject to the provisions of SCAQMD Rule 1466 – Control of Particulate Emissions from Soils with Toxic Air Contaminants. Ambient monitoring of particulate matter smaller than 10 micrometers (PM10), appropriate signage, stockpile covering, and recordkeeping will be completed in accordance with the provisions of Rule 1466. On-site activities will also be completed to adhere to SCAQMD Rule 403 – Dust Control, to minimize emission of fugitive dust. Monitoring will be conducted during all soil disturbance activities by qualified technicians under the supervision of a Certified Industrial Hygienist. 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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