WORK PLANS - Laserfiche WebLink

Home Browse Search

ranging from 38.5 to 46.5 feet BGS. Soil samples were collected at each location, and grab groundwater samples were collected from SB-1 and SB-2. The samples were analyzed for TPH-g and BTEX. The maximum detected concentration of TPH-g in soil was 13,000 mg/kg in the sample from VE-1 at 21 feet BGS. TPH-g was detected at 180,000 micrograms-per-liter (µg/L) in the grab groundwater sample collected from SBA and 190,000 µg/L in the sample collected from SB-2. MW-1 was completed as a 2-inch diameter groundwater monitoring well screened from 20 to 46 feet BGS. VE-1 was completed as a 4-inch diameter vapor monitoring well screened from 15 to 35 feet BGS. Monitoring well MW-1 was developed and sampled on February 6, 1997. TPH-g was detected in the groundwater sample at a concentration of 160,000 µg/L. The BTEX constituents were detected at concentrations of 22,000 gg/L, 36,000 µg/L, 4,100 gg/L and 20,000 gg/L, respectively(Secor, 1996). October 1997 Well Installation In October 1997, Secor drilled one soil boring (MW-7) through the former tank excavation to a total depth of 90 feet BGS. Soil samples were collected between 34.5 and 79 feet BGS and grab groundwater samples were collected at approximately 35 and 41 feet BGS. The maximum detected concentration of TPH-g was 390 mg/kg in soil at 34.5 feet BGS and 400,000 gg/L in groundwater at 41 feet BGS. MW-7 was completed as a nested groundwater monitoring well with MW-7S constructed using 2-inch diameter casing and screened from 55 to 63 feet BGS, and MW-7D constructed with 2-inch diameter casing and screened from 80 to 85 feet BGS. Following development, MW-7S and MW-7D were sampled on October 31, 1997 and analyzed for TPH-g, BTEX, and five fuel oxygenates (methyl tertiary butyl ether (MTBE), di-isopropyl ether (DIPE), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether (TAME) and tertiary butyl alcohol [TBA]). TPH-g was detected at concentrations of 100,000 gg/L and 10,000 µg/L in groundwater samples collected from MW-7S and MW-7D, respectively. Benzene was detected in groundwater samples collected from MW-7S and MW-7D at concentrations of 19,000 µg/L and 1,300 gg/L, respectively. MTBE was detected in the sample collected from MW-7S at a concentration of 120 gg/L(Secor 1997). December 1997 Cone Penetrometer Testing Investigation In December 1997, Secor drilled three cone penetration test (CPT) borings (CPT-1 through CPT-3). CPT-1, CPT-2 and CPT-3 were drilled to depths of 125, 115, and 120 feet BGS, respectively. One soil sample was collected from CPT-1 at 125 feet BGS, and grab groundwater samples were collected at various depths from each boring. TPH-g was not detected in the soil sample. The maximum detected concentration of TPH-g in groundwater was 17,000 gg/L in CPT-2 at 82 feet BGS (Secor, 1998). 5