Laserfiche WebLink
3 �� Cardno® <br /> San Joaquin County Environmental Health Department ATC <br /> March 22,2013 Shaping the Future <br /> In September 2010,ATC conducted a soil gas study to evaluate the potential for soil vapor intrusion into the <br /> existing commercial structure located on-site. The results indicated that neither the released non aqueous phase r <br /> liquid (NAPL) present in the vadose zone or the dissolved hydrocarbons in the groundwater posed a risk to human�l ��s <br /> health. <br /> In a letter dated January 16, 2013, EHD relayed the information that they had received a No Further Action 64-rlrel�. <br /> Required Concurrence letter from the CVRWQCB, dated December 18, 2012. Since no further action was to be <br /> required,the existing monitoring wells that are present at the site no longer serve a purpose. The EHD directed <br /> the destruction of the monitoring wells used in the investigation. <br /> SCOPE OF WORK <br /> Determination of Well Destruction Method <br /> To be protective of groundwater quality, EHD has developed a policy that directs the destruction of monitoring wells <br /> by two different methods depending on the presence or absence of contamination in soil or groundwater in the <br /> vicinity of the well. <br /> Over drilling is required for wells where soil samples collected during their installation indicated the presence of <br /> hydrocarbons and where dissolved contaminants remain detected in recently collected groundwater samples. In <br /> contrast, pressure grouting could be used to destroy monitoring wells if contamination was not detected in soil <br /> samples collected during their installation and where recent groundwater samples collected from the wells proved <br /> to be free of contaminants. <br /> Cardno ATC applied the criteria to be used to determine the appropriate well destruction method as stated above. <br /> The results of this exercise are displayed in the table below. <br /> Well Characteristics <br /> Well Location in an Water Samples <br /> Well area free of known Acceptable Lab absent <br /> Construction or suspected soil Detection Contaminants of Destruction <br /> MWID Detail Known? contamination? Limits? Concern? Method <br /> Yes No Yes No Yes No Yes No PG OD <br /> MW-1 X X X X X <br /> MW-21 X X X X X <br /> MW-3 X I X X X X <br /> MW-4 X X X X X <br /> MW-5 1 X X X X X <br /> MW-6 X X X X X `f <br /> MW-7 X X X X X <br /> MW-8 X X X X X <br /> Cardno ATC used the results in the table above to plan the well destruction described below. A Well Construction <br /> Detail Table is attached as Table 1. <br /> www.cardnoatc.com <br />