ARCHIVED REPORTS XR0002755 - Laserfiche WebLink

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Ailani,c 1t,ahl,a Id(aHnl,anl AltCO strait, %iaucxr 44912 If,E Hardin+BI%d %toLkiax, ( A laouary 5 ?tkii • currently include one 20,000-gallon gasoline underground storage tank (US] ) and one 22 000 gasoline UST and associated product Imes and dispensers Excavation and removal of three gasoline USTs and associated dispensers and product lines weic performed by Getticr Ryan Cow tiuction of Dublin California between May 25 and June 9 1999 The excavated USTs consisted of three 10,000-gallon capacity USTs of double-walled hher-0ass construction Over-excavation was peifoimed in the LiST complex to accommodate the larges nc%� USA's Appiommately 631 tong of soil was ovel-cscavated I 1011 the US i complex Over-excavation of the US I complex WA, completcd and samples were collected oil June 9 1999 Six samples weic collected hom the bottom of the UST complex at approximately 19 feet bgs TP1Ig and Mt13L were reported in one sample each at concentrations of 1 02 mJkg and 0 _579 mg/kg respectively Benzene and fuel oxygenates were reported as nondetect in all samples from the UST after over-excavation Approximately 150 tons of soil was over- excavated from the product line and dispenser areas TPHg was reported in three of the six samples at a maximum concentration of 5,430 mg/kg Benzene was reported in two samples at a maximum concentration 10 6 mg/kg MtBE was reported in two samples at a maximum concentration of 55 5 mg/kg In August 2000, four groundwater monitoring wells (MW-1, MW-2, MW-3, and MW- 4) and one vapor extraction well (SVE-1) were installed at the site TPHg, benzene, and MtBE were reported in groundwater samples collected from the groundwater monitoring wells at maximum concentrations of 166,000 ppb, 10,500 ppb, and 708,000 ppb,respectively(MW-4). Fuel oxygenates TAME and 1,2-DCA were reported in all wells except MW-3 at maximum concentrations of 427 ppb (MW-4) and 23 8 ppb (MW-1),respectively. TBA was reported in wells MW-2 (215 ppb) and MW-4(26,100 ppb). ELBE was reported in well MW-4 at a concentration of 2.22 ppb PROPOSED SCOPE OF WORK The scope of work for this site assessment will include the installation of five groundwater monitoring wells,the drilling of two soil bonngs,the performance of a 500-foot radius door-to-door well survey, and the performance of a conduit study. The wells and bonngs have been proposed to evaluate the vertical and lateral extent of petroleum hydrocarbons in soil and groundwater beneath the site and the proposed locations are shown on Figure 2 The specific scope of work is discussed below Site Safety Plan. As required by the Occupational Health and Safety Administration (OSHA)Standard"Hazardous Waste Operations and Emergency Response' guidelines(29 CFR 1910 120), and by • California Occupational Health and Safety Administration (Cal--OSHA)"Hazardous Waste Operations and Emergency O?7 41286 1 IO(Wi'LAN3 doc