COMPLIANCE INFO_2008-2010 - Laserfiche WebLink

Home Browse Search

2.5 PREVIOUS SITE INVESTIGATION AND REMEDIAL ACTIVITIES Cove Contractors is closing the landfill located at the site under the oversight of the RWQCB and the CIWMB. Several documents have summarized the activities conducted on site including documentation of the closure and post-closure activities. The document titled Revised Landfill Closure and Post-Closure Maintenance Plan [Clayton Group Services (Clayton), January 16, 2006] was approved by the CIWMB in a letter dated January 26, 2006 and by the RWQCB in a letter dated February 16, 2006. This plan described how the proposed landfill capping activities, groundwater monitoring, and landfill gas monitoring were an integral part of the post-closure maintenance procedures. Once landfill closure activities were completed a closure report was submitted to the RWQCB and CIWMB. This report was titled Landfill Closure Report Cove Contractors Facility 3242 South EI Dorado Street, Stockton Co (Condor Earth Technologies - September, 2007) detailing the earthwork, geotechnical oversight and quality assurance directly related to the construction of the landfill cover system based on the approved closure plan. Additional information regarding the closure activities was requested by the RWQCB and CIWMB. Therefore a supplemental report titled Closure Report Addendum Cove Contractors Facility 3242 South EI Dorado Street, Stockton, Ca (Miller Brooks - May 8, 2008) was submitted. This report described the ancillary closure activities associated with the installation of the landfill cap including monitoring well removal, monitoring well installation, landfill gas probe installation, hydroseeding, and implementation of site security. Closure and post-closure activities include the periodic groundwater and landfill gas monitoring events, as mentioned previously. Prior to the approval of the Revised Landfill Closure and Post- Closure Maintenance Plan, periodic soil and landfill gas investigations were conducted at the site beginning in 1986. However, regular monitoring events were conducted beginning in 2006. Clayton conducted all monitoring and landfill capping activities, from June 2006 through January 2007. Beginning in May 2007, Miller Brooks conducted all landfill capping and subsequent monitoring activities as required by RWQCB Waste Discharge Requirement (WDR) Order No. R5-2007-0084. Methane concentrations reported from the landfill gas probes located in the center of the site have generally remained the same or slightly increased over time. The majority of these concentrations have been above 5%. As described in following sections, perimeter gas probes were installed at the site in 2007. The majority of the methane concentrations reported from the perimeter gas probes have remained the some and have been below 5%,with the exception of two locations (PGP-1 and PGP-2). As discussed in Section 2.2, PGP-1 and PGP-2 are most likely reporting elevated methane concentrations due to their installation within the landfill footprint. 5 AMLLER MWOOKK P:\707 Cove Contractors\Feasibility Study and Corrective Action Plan\Corrective Action Plan_Final.doc