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State of California—California Environmental protection Agency, <br /> Department of Toxic Substances Control <br /> Risk of exposure to hazardous substances from soil has been mitigated since the 1990 Remedial Investigation (RI), <br /> Surface and shallow soil contamination identified in samples collected from drainage ditches on-site in 1989 have been <br /> remediated by removing soil with concentrations exceeding the established levels and covering the entire site with <br /> asphalt. Shallow soil with elevated levels of chromium, arsenic, and copper at depths from near surface to approximately <br /> 15 feet below ground surface are covered with an engineered RCRA cap in the immediate area of the retort pits. An <br /> environmental restriction has been implemented prohibiting disturbance of the cap without authorization from DISC. The <br /> site is fenced and secure and all storm water is captured and pumped to the treatment system for processing before being <br /> discharged under an NPDES permit to the Stockton Diverting Canal. <br /> The calcium polysulfide solution used in the pilot studies was a 3% concentration in a water solution. The RAP <br /> Amendment proposes to use a calcium palysulfide solution as the injection fluid.An official NSF International Standard 60 <br /> Listing allows the use of safe use of CASCADE calcium polysulflde solution as a treatment solution in drinking water. The <br /> product is used for the destruction of residual chlorine in the water. <br /> Chromium is the contaminant of concern in groundwater in the shallow and intermediate zones (60-200') beneath and <br /> emanating from the site. Direct ingestion of groundwater containing chromium represents a potentially complete exposure <br /> pathway, There are five (5)domestic wells, one (1) irrigation, and four(4)municipal production water wells that have been <br /> identified downgradient from the site that continue to be monitored and sampled to ensure chromium concentrations are <br /> below the MCI. The existing extraction and treatment system has reduced the concentrations on and off site and <br /> maintains hydraulic control. <br /> The proposed work on the Franklin school site will be performed during periods when school will not be in session, Work <br /> will be scheduled when school is out of session and the athletic field has reduced usage. Atter field activities are <br /> completed, surface completion will be restored to like original condition. The area of the proposed field activities will not <br /> interrupt the listed services. The project is expected to occur in the spring/summer 2007 and take approximately 12 <br /> months to complete. A notification to interested parties is expected to be sent out prior to the start of field work. <br /> Findings of Significant Effect on Environment: <br /> The Department of Toxic Substances Control (DISC)has prepared an Initial Study pursuant to the requirements of the <br /> California Environmental Quality Act(CEQA,Section 21000 at seq., Califomia Public Resources Code)and implementing <br /> Guideline (Section 15000 at seq_, Title 14, California Code of Regulations). Based upon this analysis, DTSC has <br /> determined that the proposed project will not have a significant effect upon the environment. <br /> (R copy of the Initial Study which supports this finding is attached,) <br /> Mitigation Measures: <br /> DTSC has determined that the project does not require any mitigation measures beyond those incorporated as part of the <br /> project description. <br /> Branch Chief Signature Date <br /> Branch Chief Name Branch Chief Title Phone# <br /> OTSC 1327(1/06/06) <br />