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Source <br />Underground piping connected to an above ground storage tank was found to be <br />leaking in 1996, resulting in the contamination of soil and groundwater. <br /> <br />Actions <br />December 1996: Immediate response after discovery of the release included excavation <br />of approximately 15 cubic yards of soil containing diesel fuel to the water table and <br />removal of approximately 3,000 gallons, or about 20,850 pounds, of diesel and 2,000 <br />gallons of mixed diesel and water from the excavation. <br />June 1999: Condor Earth Technology installed six diesel recovery wells and three <br />monitoring wells to recover Light Non-Aqueous Phase Liquid (LNAPL). <br />June 1999 to March 2011: Condor recovered 260 gallons LNAPL (1,807 pounds) by <br />bailing, passive and active skimming, and absorbent socks. <br />February 2012: Conestoga Rovers & Associates (CRA) submitted the LNAPL Remedial <br />Feasibility Study which provided a Conceptual Site Model for the facility. <br />June 2015: CRA recommended a different remediation strategy in the Site Assessment <br />Work Plan Addendum, as the on-going limited LNAPL recovery would result in an <br />extended remedial time frame. <br />June 2015: AdvancedGeo Environmental (AGE) installed a Dual Phase Extraction <br />(DPE) Remediation System. This system operated for a total of 201 days from 2015 to <br />September 2018. AGE estimated that 3,400 lbs of dissolved TPH and 7,995 lbs of <br />absorbed TPH have been removed by the DPE system. <br />October 2015: AGE installed two additional remediation wells and conducted soil and <br />grab groundwater sampling. The Remediation Well Installation & Additional Site <br />Assessment Report dated 29 December 2015 defined the extent of the plume and <br />concluded that diesel impacted soil was limited to a depth of 20 feet bgs. <br />February 19-21, 2020: Confirmation sampling verified that no constituents of concern <br />have been detected in wells MW-1 through MW-4, and although the sample from <br />recovery well RW-8 contained 17,000 ug/l of TPH-d, no free product was encountered <br />in any recovery well. Soil samples collected adjacent to previous sampling points <br />confirmed a decreased concentration of diesel adsorbed onto soil (Attachment 2). Grab <br />groundwater samples collected around the former furnace building found TPH-d in <br />shallow groundwater, with a highest concentration of 580 ug/L, far below the <br />concentrations found in the majority of recovery wells. <br /> <br />Well Destruction <br />AGE submitted the 12 February 2020 Well Destruction Work Plan with was approved by <br />Central Valley Water Board staff in a 10 March 2020 letter. Destruction activities took <br />place on 18-20 March 2020, before the end of the 30-day comment period. All