The Regional Water Quality Control Board amended U.S. Marine Corps Base Camp Pendleton’s waste discharge requirements for the Las Pulgas Landfill.
The 7-0 RWQCB vote Wednesday, Feb. 10, established procedures and technical specifications to remove the existing Phase I unit side slope liner system and to construct the engineered alternative Phase I unit side slope liner system. The revised waste discharge order recognized Marine Corps efforts to implement corrective actions at the landfill and resume waste disposal operations within the Phase I unit.
The Marine Corps has operated the 89-acre landfill since 1971. The Class III landfill for non-hazardous solid waste only accepts waste generated on the base. Camp Pendleton is dependent upon groundwater, although the nearest groundwater supply is approximately 5 miles away from the landfill.
In January 2017, the Marine Corps notified the RWQCB of a potential failure within the Phase I unit side slope liner system. RWQCB staff visited the landfill in February 2017 and observed bulging and slumping of the side slope liner system.
The Marine Corps conducted field investigations and confirmed the failure of the unit side slope liner system while also determining that groundwater seeps hydrated and compromised the integrity of the clay layer which is the lowermost component of the side slope liner system.
The Marine Corps’ conclusion was that the seeps were created by a rise in groundwater elevation caused by a series of large storms. Daily waste disposal operations were moved from the Phase I unit to the Phase II unit.
The Marine Corps conducted an engineering feasibility study and prepared a corrective action plan to mitigate the slope liner system failure. The Marine Corps also worked with the RWQCB to ensure that the plan and the proposed alternative liner system complied with federal and state regulations. The RWQCB accepted the corrective action plan in August 2020.
The corrective action plan provides the procedures and technical specifications to remove the existing liner system and construct an alternative liner system. The alternative liner system will have a continuous drainage layer, which is expected to prevent groundwater seeps from interacting with the liner system materials.
A 45-day public review and comment period preceded the Feb. 10 board action.
Joe Naiman can be reached by email at [email protected].