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MONITORING AND REPORTING PROGRAM <br /> MOBIL OIL CORPORATION <br /> FORMER MOBILE GASOLINE SERVICE STATION 10-NP4 <br /> GROUND WATER TREATMENT SYSTEM DISCHARGE <br /> SAN JOAQUIN COUNTY -2- <br /> Sampling <br /> Constituents Units Tyne of Sample Frequency <br /> Toluene' µg/l Grab Quarterly2 <br /> Xylene' µg/l Grab Quarterly' <br /> Bioassay % Survival Grab Quarterly <br /> z By EPA Method 8015, Modified (GCFID, EPA 5030) . <br /> Analyses shall be conducted weekly for four consecutive weeks following initial <br /> discharge to the storm drain from the treatment system. The weekly data shall <br /> be submitted to the Board within 30 days of taking each sample. <br /> ' By EPA Method 602, or an equivalent method. <br /> GROUND WATER MONITORING <br /> Prior to construction, plans and specifications for ground water monitor and/or <br /> extraction wells shall be submitted to Board staff for review and approval . <br /> No later than 90-days after issuance of this Order, the Discharger shall Board staff <br /> with a ground water monitoring program that will demonstrate the effectiveness of the <br /> ground water extraction and treatment system. <br /> The ground water monitoring network consists of 12 monitor wells and a proposed <br /> extraction well as shown on Attachment C. <br /> REPORTING <br /> For ground water monitoring, quarterly reports are required in Section 2652(d) of the <br /> Underground Tank Regulations, Chapter 16, Division 3, Title 23, of the California Water <br /> Code of Regulations. Recommended reporting formats are included in the Tri-Regional <br /> Recommendations and Appendix A. Ground water monitoring results, volumes of extracted <br /> ground water and product, and remediation system operation information must be <br /> included. <br /> In reporting the monitoring data, the Discharger shall arrange the data in tabular form <br /> so that the date, the constituents, and the concentrations are readily discernible. <br /> The data shall be summarized in such a manner to illustrate clearly whether the <br /> discharge complies with waste discharge requirements. <br /> Quarterly monitoring results shall be submitted by the 20th day of the month following <br /> each calendar quarter. The quarterly reports shall have the results of the ground <br /> water monitoring and the treatment system influent and effluent monitoring presented <br /> in separate volumes. <br /> An annual report evaluating the effectiveness of the ground water cleanup shall be <br /> submitted to the Board by 30 January of each year. At a minimum, the report shall <br /> contain the following information: both tabular and graphical summaries of the <br /> monitoring data obtained during the previous year; trends in the concentrations of the <br />