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Appendix C:Initial Study Checklist Former Marley Cooling Tower Company,Stockton,CA <br /> ❑ Potentially Significant Unless Mitigated <br /> ® Less Than Significant Impact <br /> ❑ No Impact <br /> References Used: <br /> 1, 3 <br /> , 8H rotagyandWateeQtrality <br /> Description of Baseline Environmental Conditions: In 1992, a groundwater treatment system and remedial well field began <br /> operating and extracting groundwater contaminated with total dissolved chromium. An electrochemical precipitation <br /> system and ion exchange system are used to remove chromium from the extracted groundwater. All treated groundwater <br /> is then discharged to the Stockton Diverting Canal according to the requirements in Central Valley Regional Water Quality <br /> Control Board (RWQCB) Order R5-2008-0030. Monitoring and reporting is conducted in accordance with the existing <br /> Monitoring and Reporting Program (MRP) for the Site. Groundwater is first encountered at approximately 60 feet bgs at <br /> the site, Three water bearing zones have been identified at the site and they are; Shallow Zone from approximately 60 to <br /> 85 feet bgs, Intermediate Zone from 120 to 180 feet bgs., Deep Zone from 180 to 250 feet bgs. Groundwater in the area <br /> of the retort pit has elevated concentrations of hexavalent chromium detected in excess of 20,000 micrograms per liter. <br /> There are local domestic, irrigation, and production wells that are being sampled on regular intervals due to historical site <br /> contamination Impacting the wells. Current chromium concentrations reported in samples collected from the wells are <br /> below MCLs. Proposed remediation should improve water quality in the area. The cleanup goal established for the Site <br /> is 0.050 mglL dissolved in groundwater based on the Calffomia MCL. <br /> Analysis as to whether or not project activities would: <br /> a. Violate any water quality standards or waste discharge requirements. <br /> Impact Analysis: Local wells and specific sample locations would continue to be monitored and sampled for <br /> associated contamination as specified in associated permits by the regulatory agencies (Regional Water Quality <br /> Control Board, Central Valley Region and DTSC)to comply with water quality standards. <br /> Conclusion: <br /> ❑ Potentially Significant Impact <br /> ❑ Potentially Significant Unless Mitigated <br /> ® Less Than Significant Impact <br /> ❑ No Impact <br /> b. Substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would <br /> be'a net deficient in aquifer volume or a lowering of the local groundwater table level (e.g., the production rate of pre- <br /> existing nearby wells would drop to a level which would not support existing land uses or planned uses for which <br /> permits have been granted). <br /> Impact Analysis: No impact is anticipated. The activities would actually be adding solution to the water table for a net <br /> gain effect. <br /> Conclusion: <br /> ❑ Potentially Significant Impact <br /> ❑ Potentially Significant Unless Mitigated <br /> ® Less Than Significant Impact <br /> ❑ No Impact <br /> e. Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a <br /> stream or river, in a manner which would result in substantial erosion or siltation on or off-site. <br /> Impact Analysis: No alteration of a stream or river Oil occur. <br /> Conclusion: <br /> El Potentially Significant impact <br /> ❑Potentially Significant Unless Mitigated <br /> ❑Less Than Significant Impact <br /> ®No Impact <br /> Page 15 of 25 <br />