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page 2, 1645 Cherokee Road v <br /> On September 2, 2005 SJC/EHD received a phone call from the consultant onsite directing <br /> the excavation, reporting that they had encountered groundwater at approximately 75 feet <br /> bsg. SJC/EHD personnel went to the site to observe; a grab groundwater sample was <br /> collected, but no documentation of, or laboratory analytical report for this sample was <br /> submitted with the CLS Report. <br /> Four groundwater monitoring wells were formerly located at this site. They were destroyed <br /> prior to the start of the remedial excavation. TRC states in the Work Plan that the highest <br /> concentration of contamination in any of these wells was 100 micrograms per liter(Ng/1) <br /> total petroleum hydrocarbons as diesel (TPHd). It was not noted, however, that the wells <br /> from which these results were obtained were not located near the source area. One well, <br /> MW-4, was eventually located in the source area, but it was built too shallow and no <br /> groundwater samples from it were ever collected and analyzed. <br /> Per the Remedial Action Plan, the four groundwater monitoring wells were to be reinstalled <br /> following completion of the excavation. TRC instead proposes to install four soil borings to <br /> collect soil and grab groundwater samples. TRC did not describe the drilling method they <br /> intend to use to install the borings. If this is the way you wish to proceed with your site <br /> investigation, SJC/EHD will approve it with the conditions that: 1) you understand and agree <br /> that the installation of groundwater monitoring wells may still be required; 2) the proposed <br /> boring locations are to be moved for more appropriate collection of grab groundwater <br /> samples near the original source of the contamination from the former diesel underground <br /> storage tank (UST); and 3) one boring must also be located near the western margin of the <br /> excavation (possible location of sample WWCSF-78). <br /> Please proceed with submittal of a brief addendum to the work plan stating what drilling <br /> method you intend to use. Due to the depth required, SJC/EHD does not recommend <br /> attempting to use a Geoprobe. Include an updated map showing alternate boring locations <br /> to fulfill the conditions stated above. If you wish to install more than four borings, that can <br /> be approved upon provision of sufficient technical justification. The addendum is due for <br /> submittal to SJC/EHD no later than December 21, 2007. <br /> Per California Code of Regulations, Title 23, Chapter 30, Section 3890, all contaminated <br /> UST sites must electronically transmit to Geotracker, the State Water Resources Control <br /> Board database website, reports of work performed, laboratory data from chemical analysis <br /> of samples, monitoring well elevation survey data, site maps and quarterly groundwater <br /> depth measurements. Reports from your site have not been submitted to Geotracker. <br /> Please proceed with the immediate submittal of all required site data and reports to <br /> Geotracker. <br /> If you have any questions please call Lori Duncan at (209) 468-0337. <br /> Donna Heran, REHS, Director <br /> Environmental Health Department <br /> Lori Duncan, Senior REHS Nuel C. Henderson, Jr., PG <br /> LOP/Site Mitigation Unit IV LOP/Site Mitigation Unit IV <br /> cc: James Barton CVRWQCB <br /> Keith Woodburne, TRC <br />