ARCHIVED REPORTS_XR0011731 - Laserfiche WebLink

Home Browse Search

i i Each ground monitoring well was completed with 20 feet of well screen section The wells were constructed using two 2-inch diameter, schedule 40 PVC casing with the following designs and ' material Monitoring well MW-1 was completed with 0 02-inch slotted screen, the screen interval was installed from depths of 15 to 35 feet bsg A filter pack was Installed using#3 Lonestar sand from 13 to 35 feet bsg Bentonite chips were used to make a one-foot transition seal above the sand ' pack Monitoring wells MW-2 through MW-4 were completed with 0 02-Inch slotted screen, the screen interval was installed from depths of 10 to 30 feet bsg A filter pack was installed using #3 Lonestar sand from 9 to 30 feet bsg Bentonite chips were used to make a one-foot transition seal ' above the sand pack The remaining annular space was backfilled to within six Inches of surface grade with Portland cement A traffic-rated well box(8-inch diameter)was installed over each well, ' in accordance with County regulations • TPH-g was detected in one of the twelve soil samples analyzed(MW 1-15)at a concentration ' of 990 mg/kg BTEX compounds were also detected in the same soil sample at concentrations of 3 9 mg/kg, 33 mg/kg, 17 mg/kg, and 110 mg/kg, respectively BTEX compounds were also detected in two other soil samples collected from boring MW-1 Toluene,ethylbenzene,and total xylenes were detected in sample MW 1-30 at concentrations of 0 012 mg/kg, 0 005 mg/kg, and 0 028 mg/kg, respectively BTEX compounds were detected in sample MW1-35 at concentrations of 0 008 mg/kg, 0 024 mg/kg, 0 007 mg/kg, and 0 037 mg/kg, respectively Soil samples collected from the other soil borings (MW-2 through MW-4) did not contain detectable concentrations of petroleum hydrocarbons The oxygenated compound methyl tertiary-butyl ether (MTBE) was not detected in the soil t . samples analyzed ' On 06 November 2000, two ground water monitoring wells were installed off-site Soil bonng/momtonng wells MW-5 and MW-6 were advanced vertically to depths of 25 bsg as part of assessment activities related to the former USTs at the site Soil borings MW-5 and MW-6 were ' completed as ground water monitoring wells utilizing 2-inch diameter,schedule 40,blank PVC well casing from 10 feet to 25 feet bsg and perforated,2-inch diameter PVC well casing(0 020-inch slot) from 10 feet bsg to surface A filter pack was installed using#3 Lonestar sand from 8 feet to 25 feet ' bsg Bentonite chips were used to make a one-foot transition seal above the sand pack The remaining annular space was backfilled to within six inches of surface grade with portland cement A traffic-rated well box (8-inch diameter)was installed over each well, in accordance with County ' regulations • TPH-g, BTEX compounds, and MTBE were not detected in the soil samples analyzed On 14 November 2000, three soil probe borings (P9 through P11)were advanced at the site, under ' observation by the EHD Probe borings were advanced in the area of the former USTs and in the areas north and east of the former UST dispenser Boring P9 was advanced to a depth of 3 5 feet bsg, boring P10 was advanced to a depth of 40 feet bsg, and boring P11 was advanced for collection of ' a grab ground water sample to 20 feet bsg • TPH-g and BTEX compounds were detected in soil samples collected from probe boring P9 Advanced GeoEnvironmental,Inc