Laserfiche WebLink
%WOO .r <br /> Quik Stop Station No. 076 Page 2 <br /> 1030 South Olive Avenue January 14,2009 <br /> Stockton, California 95215 <br /> • Comparison of analytical data for groundwater collected from MW5 at the JAMAR site <br /> and MW-1 at the Quik Stop site indicates concentrations for total petroleum <br /> hydrocarbons quantified as gasoline (TPHg) have been significantly higher in <br /> groundwater collected quarterly from MW-1; and methyl tertiary-butyl ether (MTBE), <br /> detected at low concentrations in groundwater collected quarterly from MW5 at the <br /> JAMAR site, has not been detected in any groundwater samples collected from MW-1. <br /> The EHD has concluded that analytical data do not demonstrate a clear relationship <br /> between results from the two monitoring wells. <br /> Therefore, the EHD does not approve deferral of a work plan to address the lateral and vertical <br /> extent of impacted groundwater and an assessment of the potential for vapor intrusion into the <br /> existing onsite buildings by evaluation of Environmental Screening Levels (ESLs) and California <br /> Human Health Screening Levels (CHHSLs), as directed by letter dated August 8, 2008. Submit <br /> the work plans/assessments within fourteen days of date of this letter. <br /> If Horizon can demonstrate that contaminants of concern detected in groundwater collected from <br /> MW-1 are the result of petroleum hydrocarbon contamination from the JAMAR site, the EHD <br /> will reconsider its position. To achieve these objectives the EHD recommends the following: <br /> • Submit hydrogeological cross sections to demonstrate migration pathways between the <br /> JAMAR site and the Quik Stop site. <br /> • Conduct additional site assessment to delineate the petroleum hydrocarbon plume at the <br /> Quik Stop site and to determine if the petroleum hydrocarbon plume is coming from <br /> the JAMAR plume. <br /> • Resurvey MW-1 using the same survey markers used for surveying the monitoring <br /> wells at the JAMAR site; then establish the groundwater gradient by collecting depth- <br /> to-groundwater measurements from MW-1 on the same day wells are monitored at the <br /> JAMAR site. <br /> Please contact Vicki McCartney, Senior Registered Environmental Health Specialist, at (209) <br /> 468-9852, or by email at vrnccartney ri sjcehd.com if you have any questions. <br /> Sincerely, <br /> Victoria L. McCartney, REHS Nuel C. Henderson,Jr., PG <br /> Senior Registered Environmental Health Specialist Engineering Geologist <br /> c: Mr. Rexford K. Smith, PG, Horizon Environmental Inc., 4970 Windplay Drive, No. C5, El <br /> Dorado Hills, California 95762 <br /> Mr. James L.L. Barton, PG, California Regional Water Quality Control Board Central Valley <br /> Region, 11020 Sun Center Drive, Suite 200, Rancho Cordova, California 95670 <br />