Laserfiche WebLink
GROUNDWATER ASSESSMENT REPORT <br /> 11. Discuss concentrations and mass changes over time, and current concentrations of <br /> contaminants remaining in groundwater at the site. <br /> MTBE was first identified in soil duringUST removal activities In response to the <br /> p <br /> detected concentration of MTBE,the SJCEHD required additional soil and groundwater <br /> investigations Since the initial detection and soil removal activities,only 15 ppb of MTBE <br /> was detected in one groundwater sample from MW-3 (January 2002) MTBE has not been - <br /> detected since Based on four quarters of monitoring and subsequent soil and groundwater , <br /> investigations, if MTBE remains on site it is extremely localized and at mmor <br /> concentrations <br /> 12._Provide_isoconcentration maps_of-contamanants_of-concern to_defane the-lateral and <br /> vertical extent of contaminants remaining in soil and groundwater. The contour maps <br /> should present an estimated"zero line"of contaminant concentrations both on and off ' <br /> the site <br /> MTBE has not been detected at the site since January 2002 and then it was only a very low ' <br /> concentration in one well <br /> 13. Provide a summary of the remedial method(s) used to clean up the site Include the <br /> calculated zone of influence, assumptions used to design the remedial system(s), and the <br /> duration of remedial activities. <br /> Remediation was not necessary for this site No remediation activities were required or <br /> have been implemented <br /> 14. Provide a discussion of whether background is unattainable using best available <br /> remediation method(s) <br /> Laboratory analyses has not detected MTBE or any other chemical of concern above the �t <br /> laboratory reporting limits since January 2002 when a low concentration was detected in <br /> MW-3 Soil and groundwater is not impacted from the former UST Remediation methods ' <br /> were not necessary for this site No remediation activities were required or have been <br /> implemented <br /> 15. Provide a discussion(and estimate)of contaminant mass remaining in soil and <br /> groundwater versus contaminant mass removed or destroyed by soil excavation or <br /> remedial actions <br /> A mass of MTBE-impacted soil was not identified through soil sampling and analysts <br /> Residual concentrations localized near the former UST excavation do not represent a -_ <br /> significant mass capable of migrating vertically downward through the soil Remediation <br /> methods were not necessary for this site No remediation activities have been ' <br /> implemented <br /> Groundwater Montnnng and Sampling Report- F-4 FSA/200252 <br /> Request for No Further Action December 2003 S <br />