WORK PLANS - Laserfiche WebLink

Home Browse Search

VYork Plan T3 Frontier Transportation � � (,;A Page 2 n through MW-7) to assess the extent of subsurface contamination beneath the site (See Figure 2, Site Layout Map). Soil samples were collected every five feet. Laboratory analysis of soil samples identified no detectable concentrations of TPH-g, BTEX, or MTBE. Groundwater samples were subsequently collected. Results are tabulated in Table 1 . .00 In January 2000, BEH advanced two borings (B-5 and B-6), installed four additional groundwater monitoring wells (MW--8 through MW- 11), and collected nine soil vapor samples ' V �I. for a soil vapor survey as part of an additional site assessment (See Figure 2). Soil sample } � 0 5a l vc, ur ICY analysis identified no detectable concentrations of petroleum hydrocarbons with the exception of s a ,Vles t{� \0 boring B-6 . Maximum contaminant levels in B-6 were identified 100 mg/kg as TPH-g, 2,343 r 4 p k as BTEX, and 10,600 as MTBE at 10 ' b Maximum soil vapor concentrations Frf� g µmg g• P were identified at sample point V5 at 4' bg. Groundwater samples were subsequently collected from all monitoring wells . Groundwater results are tabulated in Table I Viand soil vapor sample n i f results are presented in Table 2. In May 2002, BEII installed two additional groundwater monitoring wells (MW- 12 and MW- 13) screened from 30' bg to 40' bg. Soil sample results identified maximum TPH-g, BTEX, and MTBE concentrations of 700 mg/kg, 115,000 µg/kg, and 25,000 µg/kg in soil collected from MW- 13 at 10' bg. Soil concentrations attenuate by 99% at 15' bg. No detectable TPH-g, BTEX, �, - . and MTBE were identified in MW- 12 . Also, monitoring well MW-3 was abandoned prior to i _ jexcavation and removal of 325 tons of impacted soil and replaced by MW-3R . ( _I In June 2003, BEII installed one groundwater monitoring well (MW-14), and collected soil samples every five feet to further assess the extant of soil and groundwater contamination f beneath the si oil sample analysis identified detectable concentrations at 106 ug/Kg and 1020 —�a / ug/Kg as B at 5 ' b and 10 'bg respectively. No detectable concentrations of BTEX o� ' petroleum hydrocarbons wMe found in the other soil samples. YY� es� /7Jfa6 E A rIeruifr .by Ae0III J 3.0) SITE GEOLOGY/HYDROGEOLOGY BaGo raGr�44 ov tuF hnldl The site is located on the boundary of the Sacramento Valley and the San Joaquin Valley y„ within the west-central portion of the Great Valley Geomorphic province of California. The Great Valley has been filled with a sequence of older to younger alluvium of Pliocene to IHolocene age which overlay sedimentary rocks of Cretaceous to Tertiary age. These sedimentary units, in turn, overlay a crystalline basement of Paleozoic and Mesozoic metamorphic and igneous rocks . The shallow subsurface geology in the site vicinity is a heterogeneous mix of gravel, sand, silt, and clay (Reference; Site Characterization Report, Twining Laboratories, October 16, 1996) . BEII encountered predominantly clays with some silts and sands from 0' to 40' bg during well advancement. I I co VIP1'V6 ., 17 . x ,