Lakewood Plaza Removal Action Workplan

Project Description: The project consists of implementing the Lakewood Plaza Removal Action Workplan (RAW) to address the presence of tetrachloroethylene (PCE) and trichloroethylene (TCE) in groundwater beneath approximately 7.3 acres of land located in Long Beach, CA (Site). The project activities entail performing on-Site treatment of groundwater using enhanced reductive dichlorination (ERD, a process that consists of injecting microbes capable of converting contaminants to inert substances) to achieve groundwater remedial action objectives and eliminate future concerns of vapor intrusion due to off-gassing from groundwater. Background: The Site is a commercial retail property comprised of four parcels (Los Angeles County APNs 719-1027-25, -27, -28, and -29) situated at the northwest corner of East Spring Street and Palo Verde Avenue in the city of Long Beach. The Site was initially used for agricultural purposes and was developed as a shopping center in the 1950s. Additional buildings were constructed in the 1960s, and the number and footprint of the buildings have not changed since that time. Two dry cleaning businesses previously operated on the Site, one of which (Happy Hanger Cleaners) historically used PCE until approximately 2003. Other businesses on site include a dental clinic, a gym, a bakery, a nail salon, and a grocery store. The Site also contains asphalt-paved parking areas, concrete walkways, and palm trees and other minor landscaping. Residential properties are located immediately north and west of the site, and commercial retail properties are located east of the site across Palo Verde Avenue and south of the site across East Spring Street. There are five groundwater monitoring wells currently at the site. Groundwater monitoring is currently conducted on a semi-annual frequency. The project applicant and DTSC entered into a Standard Voluntary Agreement on November 26, 2019 (Docket No. HAS-FY19/20-037). Previous Investigations: In April 2019, a Phase I Environmental Assessment was conducted on Site. As part of the assessment, soil vapor probes were installed at 5 feet below ground surface (bgs) either inside the tenant space adjacent to the Happy Hanger Cleaners building, or in the parking lot immediately behind the dry-cleaning businesses. PCE was detected in each of the soil vapor samples at elevated concentrations. In May 2019, indoor air, soil, groundwater, and additional soil vapor samples were collected to evaluate the potential for vapor intrusion into the tenant spaces and to delineate the lateral and vertical extent of PCE concentrations in the subsurface. Elevated concentrations of PCE were found in soil vapor and groundwater in the immediate area surrounding the source area on Site, with the highest concentrations present at the former source area adjacent to the dry-cleaning machine in the Happy Hangers Cleaners business. In February 2022, additional sampling of soil, soil vapor, indoor air and groundwater were conducted as part of the Supplemental Site Investigation. Elevated concentrations of PCE were found in soil vapor and groundwater in the immediate area surrounding the source area on Site, with the highest concentrations adjacent to the former dry-cleaning machine in the Happy Hangers business. From July 2023 to October 2024, a Soil Vapor Extraction (SVE) Pilot Study was conducted on Site. The SVE system was turned off for rebound evaluation, then restarted November 2024 until December 2024. During November 2024 rebound evaluation, vapor samples were collected from the individual SVE wells, the highest concentrations were found in the wells located within the former Happy Hanger Cleaners tenant space, but remained well below the target cleanup goals. In February 2025, SVE system was removed from Site. Project Activities: Implementation of the RAW involves a process known as enhanced reductive dichlorination (“ERD”) which will be used to reduce concentrations of volatile organic compounds (VOCs) in the area of the source plume core area and beneath the former dry cleaning facilities. ERD works by injecting a solution containing microbes into the ground, which then reacts with contaminants and converts them to inert end products. ERD will be implemented in an area measuring approximately 10,000 square feet in the area of the core plume source area around existing monitoring wells MW 1 and MW 3 and beneath the former dry-cleaning facilities. Implementation will consist of a single injection in up to 17 injection points. The injection wells will be installed using a drill rig, with boring widths measuring approximately 2 to 3 inches in diameter. The target depth of the injection is approximately 15 to 35 feet bgs at the core plume source area around existing monitoring wells MW 1 and MW 3 and approximately 15 to 55 feet bgs and beneath the dry cleaning facilities utilizing angle borings. The estimated time/duration of the injection is six to eight working days. Monitoring of groundwater will be performed to evaluate baseline conditions, performance and for compliance with applicable permits. It is noted that additional rounds of injections may be necessary depending on the VOC concentrations in the wells post injection. Limited monitoring of indoor air is proposed until cleanup goals are confirmed to be achieved for soil vapor and groundwater. The RAW estimates it will take 1 to 3 years to achieve the reduction goals. Sampling and analysis will be performed as required by Waste Discharge Requirements (WDR) to be issued by the Regional Water Quality Control Board (RWQCB). Compliance monitoring is typically performed on a quarterly basis. The results of compliance testing will be reported in the required WDR monitoring reports. 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.