Laserfiche WebLink
Ms. Dot Lofstrom <br /> Page 5 of 6 <br /> • r soil discoloration were noted and PID readings were all zero <br /> No petroleum hydrocarbon odors o o g <br /> in the soil samples collected from boring MW2. The boring/well construction log for MW2 is <br /> included in Attachment A. <br /> 3.2 Soil Analytical Results <br /> No TPHg, BTEX, 1,2 DCA., EDB or gasoline oxygenate additives were detected in the soil. Soil <br /> analytical results are summarized in Table 2. Laboratory reports and chain of custody documentation <br /> are included in Attachment C. <br /> 3.3 Groundwater Analytical Results <br /> TPHg and BTEX were not detected in wells MW 1 or MW2. The only analyte detected in well MW 1 <br /> was MTBE at a concentration of 11 parts per billion(ppb). No gasoline oxygenate additives, 1,2 DCA <br /> or EDB were detected in well MW2. Groundwater analytical results are summarized in Table 3. <br /> Laboratory reports and chain of custody documentation are included in Attachment C. <br /> 4.0 SUMMARY <br /> • One groundwater monitoring well (MW2) was installed to a depth of approximately 40 feet <br /> . bgs at the site. First groundwater was found at a depth of approximately 33 feet bgs and <br /> subsequently rose to 25.68 feet bgs. The water table elevation in well MW2 was slightly <br /> higher than in well MW L This is attributed to the large difference in screened intervals. <br /> • Field observations (odors, staining, PID readings) indicated that soil in MW2 was not <br /> impacted by the unauthorized release. Laboratory analysis detected no contaminants in the <br /> soil samples collected from boring MW2. <br /> 1 were detected in the water sample from well MW l. The <br /> • Other than MTBE, no analytes p <br /> concentration of MTBE detected in well MW 1 was 11 ppb, which is less than the primary <br /> maximum contaminant level (MCL) of 13 ppb for drinking water. The MTBE concentration in <br /> well MW 1 has decreased during each of the last two sampling events. <br /> • No analytes were detected in the water sample collected from well MW2. <br /> 5.0 CONCLUSIONS <br /> • The lateral and vertical extent of soil contamination has been defined. Soil contamination is <br /> confined to an area of approximately 700 square feet within close proximity to the former UST <br /> location. Soil contamination occurs between the depths of approximately 17.5 and 32.5 feet below <br /> grade, and consists of highly weathered gasoline range hydrocarbons depleted in BTEX. <br /> • <br />