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0 0 <br /> San Joaquin County <br /> Environmental Health Depnartment DIRECTOR <br /> �.• � .o M Donna Heran,REHS <br /> e: 1868 East Hazelton Avenue <br /> Stockton, California 95205-6232 PROGRAM COORDINATORS <br /> �. '•.1 :� Robert McClellon,REHS <br /> Jeff Carruesco,REHS,RDI <br /> cq.. :... :P - Website:www.sjgov.org/ehd Kasey Foley,RENS <br /> ��FORd Linda Turkatte, REHS <br /> Phone: (209) 468-3420 Rodney Estrada,REHS <br /> Fax: (209) 464-0138 Adrienne Ellsaesser,REHS <br /> June 4, 2014 <br /> Mr. Sheldon Teranishi <br /> 1600 Durham Ferry Road <br /> Tracy, California 95304-8799 <br /> Subject: Former George's Service <br /> 1600 Durham Ferry Road <br /> Tracy, California 95376 <br /> Dear Mr. Teranishi: <br /> The San Joaquin County Environmental Health Department(EHD) has received and reviewed <br /> Second Semi-annual Groundwater Monitoring and Remedial Effectiveness Report (the <br /> Report), dated 29 January 2014, prepared by your consulting firm, Ground Zero Analysis, Inc. <br /> (GZA) on your behalf for the above-referenced site. In the Report, GZA recommended <br /> preparation of a work plan to install additional soil vapor extraction wells outside the over- <br /> excavation backfill in areas of known impacted soil in the vicinity of the former. UST pit, former <br /> pump island and under the northwestern third of the building on the site. <br /> Before the EHD can approve an expansion of the soil vapor extraction (SVE) and insitu air <br /> sparge (IAS) system, it must be shown that the technology has been effective in its initial run. <br /> The Report does not provide an estimate of the contaminant mass removed during the <br /> reporting period or cumulatively nor does it provide an estimate of the contaminant mass <br /> recovery rate — important parameters for evaluating remedial effectiveness and justifying <br /> expansion of the system. The EHD directs that a report of these parameters be prepared and <br /> submitted to the EHD by 31 August 2014 for further evaluation of the recommendation. <br /> Include in the report the results of SVE/IAS tests (influent and effluent: air flow, vapor stream <br /> concentrations, and photo-ionization detector (PID) concentrations; identify wells involved in <br /> the tests, hours of operation, injection pressure, etc.). The data can best be reviewed in table <br /> format, and based on these site characteristics, provide professional opinion to help justify the <br /> expansion. The work plan may be prepared as proposed, but the EHD will require the <br /> information noted to evaluate and approve the work plan. <br /> The EHD notes that all monitoring reports include much information of vertical gradient on the <br /> site, but beyond amply demonstrating that the dominant vertical gradient is upward on the site, <br /> a practical utilization of such information generated for each monitoring event is not evident to <br /> the EHD. The EHD therefore recommends dispensing with the time and effort needed for <br /> calculating and reporting this information unless it can be shown that significant changes in <br /> the vertical gradient are likely to occur and that the information is required to make specific <br /> adjustments in management of the plume of dissolved contaminants. <br />