Phase II Environmental Site Assessment and Remedial Design Implementation
- Investigation and remediation of commingled hydrocarbons plumes
- Multiple stakeholders including community groups involved
- Installation of multiple groundwater monitoring and extraction well
- Installation and operation a Dual-Phase Extraction (DPE) remediation system
- Direct negotiations with the RWQCB-LA and LADWP
- Submittal of request for site closure under the RWQCB low-threat policy
EEC Environmental (EEC) has been supporting this project through various stages of the investigation and remediation for more than 10 years. Shallow groundwater beneath the site was impacted by petroleum releases from the former onsite underground storage tanks and from releases at an up-gradient offsite location. Investigation phases included detailed record reviews and research, the advancement of multiple borings, the installation of groundwater monitoring wells, soil-vapor sampling, and geophysical surveys. In conjunction with investigation phases of the project, a dual-phase extraction remedial unit was installed and piped to a series of 15 extraction wells to remediate hydrocarbon impacts.
All permitting, construction and operation & maintenance activities were completed by EEC in-house staff. The system extracted a combination of hydrocarbon impacted vapor and groundwater which is treated ex-situ by the onsite treatment system. Treated groundwater is discharged into the storm drain under an NPDES permit. Hydrocarbon laden vapors were destroyed in a thermal oxidizer then discharged under a site-specific AQMD permit. During the operation of the DPE system, a total of more than 13,000 gallons of hydrocarbons were removed from the subsurface. Following extensive negotiations with the RWQCB-LA including detail forensic analysis to determine the source, a request for closure was submitted under the low-threat UST policy.