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California&gional Water Quality Conal Board <br /> Central Valley Region <br /> Karl E. LongleN. SeD. P.E.. Chair <br /> ;lrnolof <br /> d <br /> Linda S.AdamsI schwarzenegger IU2U 5'un l�entcr Ihnc='UIQ. kanch�����n1���a-�alili�rnia �>�C�'lrhl I 1 <br /> 1<<iel�irl Jor Phlmr I�I1 -164-3291 1 :1.A 1 9 16 1-16-4-4611 <br /> urUriror <br /> i_rn lrw7117em / Imp/,\N����.��arerboards ca gm,centrak alIc_s <br /> PI owc[toll <br /> i� <br /> TO: Antonia K. J. Vorster � �, FROM: Kathleen Amaru <br /> Site Cleanup Unit Engineering Geologist <br /> Program Manager Site Cleanup Unit <br /> DATE: 26 February 2009 Cori Condon <br /> Senior Engineering Geologist <br /> Site Cleanup Unit <br /> SUBJECT: RATIONALE FOR CONSIDERING NO FURTHER ACTION, FORMER VALLEY <br /> WATER TREATMENT, 612 NORTH BUENA VISTA ROAD, STOCKTON, SAN <br /> JOAQUIN COUNTY <br /> Rationale: The brine pit which had contained salt was removed and salt-impacted soil beneath <br /> the brine pit has been excavated. The excavation of approximately 975 feet of soil removed <br /> 105 pounds of solid phase salt from the environment. Confirmation soil samples show the <br /> remaining concentration of salt in soil is 93 mg/kg. Background concentrations and/or water <br /> quality objectives for chlorides and total dissolved solids have been achieved in three of the <br /> five monitoring wells. Quarterly groundwater monitoring shows decreasing trends in the <br /> remaining two wells. Background concentrations and/or water quality objectives in the two <br /> wells will be achieved in approximately three years. <br /> Issues: In March 2005, an environmental assessment was conducted on the property to assess <br /> impacts to soil and groundwater from a leaking brine pit. Soil and groundwater analysis <br /> indicated impacts from salt. Grab groundwater samples from the source area contained up to <br /> 4900 mg/L total chloride and 8200 mg/L of total dissolved solids (TDS). Soil samples contained <br /> up to 2300 mg/kg total chloride. Background concentrations for chloride and TDS at the Site <br /> range from 100-130 mg/L and 700-1000 mg/L, respectively. Water Quality Objectives (WQOs) <br /> for chloride and TDS are 250 mg/L and 500 mg/L, respectively. <br /> During the assessment, soil and groundwater was also analyzed for petroleum hydrocarbons, <br /> because a former underground storage tank (UST) had also been on the property. Groundwater <br /> pollution from the UST is being addressed by San Joaquin County Department of Environmental <br /> Health. San Joaquin County is preparing to close the UST portion of the Site. pending <br /> destruction of monitoring wells, which are currently being used to monitor the salt and TDS <br /> impacts. <br /> California Environmental Protection Agency <br /> el I,,rrciccl Paper <br />