Laserfiche WebLink
Geological Technics!ac Page 3 <br /> ' Groundwater Momtormg Report <br /> Project No 662 2 <br /> . July 2, 2002 <br /> 1.3 Laboratory Analyses <br /> 1 The groundwater samples collected on April 15, 2002, were delivered to Sherwood Labs <br /> (Department of Health Services Certification No 1400) of Hilmar, California, for analysis <br /> ' The groundwater samples were analyzed for <br /> • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX)by method EPA method 602 <br /> Total Petroleum Hydrocarbons as Gasoline (TPH-G) by EPA method 5030/8015(M) <br /> Sherwood forwarded samples to Castle Analytical Laboratory (Department of Health <br /> ' Services Certification No 2480) of Atwater, California, for analysis of <br /> • Oxygenated Fuel Compounds (MTBE, DIPE, ETBE, TAME & TBA) by EPA method <br /> 8260 <br /> The detection limits for the above analyses are listed in Table 2 of Appendix A while the lab <br /> Y pp <br /> ' analytical results are presented in Appendix B <br /> As required under AB2886, the laboratory data was submitted electronically to GeoTracker <br /> on April 30, 2002 (confirmation# 4211215734) <br /> 2.0 FINDINGS AND DISCUSSION <br /> The results of the groundwater sample analysis show the following <br /> ' • MW-1 contained the gasoline oxygenates MTBE at 1600 pg/l, ETBE at 2 5 ug/l, and <br /> TAME at 11 ug/1 <br /> • MW-2, which is upgradient of the former USTs, has not contained contaminant <br /> ' concentrations above the laboratory detection limits for all ten quarterly events <br /> completed thus far in the investigation <br /> ' • MW-3 contained the gasoline oxygenates MTBE at 5600 gg/i, ETBE at 10 ug/1, TAME <br /> at 27 ug/l and TBA at 160 ug/1 <br /> • Figure 4 MTBE vs Groundwater Elevation - MW-3 illustrates a fairly direct <br /> ' relationship between the concentration of MTBE in groundwater and the elevation of <br /> groundwater in well MW-3 <br /> • Neither BTEX nor TPH-G was present in any of the groundwater samples above the <br /> ' laboratory reporting limits <br /> • Oxidation-Reduction Potential measurements (Table 3) show that the values for all three <br /> wells are positive, suggesting that there is a limited amount of biodegradation of the <br /> contaminant plume occurring This is to be expected, since the primary contaminant is <br /> MTBE, which is resistant to biodegradation <br />