Laserfiche WebLink
`./ Page 2 of 5 <br /> Chronology <br /> Former Morita Brothers <br /> 814 E. Charter Way, Stockton, CA 95206 <br /> ons of <br /> 09/30/1992 monitoring well MW-1 were initially impceth by low <br /> ene and totalxylenes, have <br /> TPHg and low concentrations of toluene, y <br /> been generally "non-detect" since September 2000, with rare detectable TPHg; the <br /> well provides a maximum southern extent of the impacted groundwater plume. <br /> MW-2 samples were initially impacted by moderate to high concentrations of TPHg <br /> and moderate BTEX concentrations; BTEX has mostly been absent from the well <br /> since November 2000, TPHg has persisted, but was occasionally "ND" in 2008. <br /> MW-2 demonstrated an undefined northeastward extent of the dissolved plume, <br /> justifying the later installation of MW-5. Groundwater samples from monitoring well <br /> MW-3 were initially impacted by moderate TPHg concentrations and low BTEX <br /> concentrations, but have mostly been "ND" since September 2003, providing a <br /> northwestward extent of impacted groundwater. <br /> 11/06/1992 Date of Preliminary Groundwater Assessment that discusses the September 1992 <br /> work. <br /> 03/31/1993 During this time over-excavation of the former UST pit was observed by the EHD; <br /> 05/17/1993 the excavation measured approximately 40 feet by 30 feet and was approx 18 feet <br /> deep (locally —22 feet deep), with a 42 feet by 8 feet by 6-foot deep extension. An <br /> estimated 760 cubic yards of soil was disposed at Forward Landfill. <br /> 07/06/1993 Date the EHD received Site Assessment Report dated June 1993 that discusses <br /> the March 1993 excavation and has receipts for the soil disposal at Forward <br /> Landfill. <br /> 07/27/1998 Date of EHD directive letter to delineate the lateral extent of impacted groundwater <br /> by installing additional groundwater monitoring wells. <br /> 09/16/1999 Monitoring wells MW-4 and MW-5, screened from 30 to 50 feet bsg were installed <br /> this date. MW-4 was sited near the former dispenser area and MW-5 obliquely <br /> down-gradient (northeast) of impacted MW-2. Groundwater samples collected <br /> from MW-4 were initially impacted by TPHg and BTEX, but have been "non-detect' <br /> since 03/13/2003; MW-5 samples had low BTEX concentrations on 11/16/1999 <br /> and 12/06/2001, but have generally been "non-detect' since with only rare, <br /> individual low detections. <br /> 11/12/1999 Date of Additional Site Characterization report that discusses the September 1999 <br /> work. <br /> 05/03/2000 Date of the EHD letter directing additional site characterization to delineate the <br /> vertical and lateral extent of impacted groundwater based on continued and <br /> increasing contaminant concentrations in existing groundwater monitoring wells <br /> reported in Quarterly Monitoring Report, dated 17 April 2000, and that a sensitive <br /> receptor survey be conducted. <br /> 11/20/2000 Dates monitoring wells MW-6 and MW-7 (screened 25 to 40 feet bsg), MW-106 <br /> 11/21/2000 and MW-107 (screened 55 to 60 feet bsg) and MW-104 (screened 87.5 to 90 feet <br /> 11/22/2000 bsg) were installed. Monitoring well MW-6 has been a "non-detect' well, providing <br /> an eastern boundary to the shallow dissolved plume; MW-7 was initially a "non- <br /> detect' well, but later yielded samples consistently impacted by low concentrations <br />