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f <br /> CHRONOLOGY l <br /> TRI-VALLEY GROWERS - PLANT T <br /> 26,200 GALT (aka Nowell) ROAD, <br /> THORNTON,CA.,95686 <br /> LOP PROGRAM: 35.26 SITE CODE#: 1920 <br /> 02/04/87 Six (6) underground storage tanks (UST)were removed under permit and inspection. <br /> q County Joaquin San uin CPublic Health Services, Environmental Health Division <br /> . <br /> (PHS-EHD). Soil samples and `grab' groundwater samples collected. Groundwater <br /> and soil contamination noted in "T-4& 5" pit. LOP/UST investigation revolves <br /> around this area, just east of"Fork Lift" repair shop. <br /> 08/00/87 Exceltech Consulting installs three (3) monitoring wells,MW-1 near "T2&Y, MW- <br /> 2 and MW-3 at "Fork Lift" shop area, under CVRWQCB and PHS-EHD oversight. <br /> Soil data to 16' b s for all three monitoring So g g wells listed as "ND" for TPH as <br /> Gasoline and Diesel and BTX (Ethylbenzene not analyzed). Initial groundwater <br /> samples all ND for TPH-G and BTEX for all three new monitoring wells.. <br /> Groundwater gradient to NE: <br /> 01/00/88 Exceltech installs MW-4 just NE of former UST pit at Forklift area. Soil from MW- <br /> 4 ND for petroleum at 6' & 10.5'bgs. <br /> 02/08/88 Groundwater from MW-4 records elevated levels of Benzene (630 ppb) and TPH-G <br /> (9„100 ppb),in first sampling event. <br /> 03/24/89 "Adjacent-well" (Lopez irrigation well, "30'NE of forklift area, offsite) reports ND <br /> for petroleum. Groundwater gradient to West. PHS-EHD directs Tri-Valley to <br /> define groundwater contamination plume'. <br /> 03/00/89 Consulting firm, WaterWork, installs MW-5 & 6. No soil or groundwater <br /> contamination detected in new well installations. Gradient is still Westerly. <br /> WaterWork reports a 500 gallon UST is present on Lopez property, about 20'NE of <br /> forklift area, offsite. Tri-Valley directed to conduct quarterly monitoring. <br /> 03/27/89 Over-excavation and soil sample collection from "T4&5" former location. <br /> 12/00/89 Excavated soil from tank pits that was aerated on site was placed back into the <br /> former tank pits along with clean material. <br /> 05/00/91 Operation of low flow,pump and treat remedial action begins onsite from 2" <br /> monitoring well #4 onsite after CVRWQCB approval. Dischargeof carbon-treated <br /> water to storm system onsite for discharge to "facilities field" under Discharge <br /> permit. <br /> 2nd QTR-94 Quarterly Monitoring of groundwater monitoring wells and pump.an:d treat system <br /> ends with PHS-EHD approval and CVRWQCB concurrence. <br /> 1 f <br />