ARCHIVED REPORTS_XR0005738 - Laserfiche WebLink

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Cis t • DISCUSSION: Total petroleum hydrocarbons as gasoline(TPHg)were reported in four of twelve monitoring wells sampled this quarter at concentrations ranging from 57 ppb(MW-7) to 1,000 ppb(MW-1) Benzene was reported in four of the twelve monitoring wells at concentrations ranging from 0 53 ppb(MW-3)to 42 ppb(MW-1) Methyl tert-butyl ether(MtBE),analyzed using EPA Method 8260B,was detected in eleven of the twelve monitoring wells at concentrations ranging from 0 93 ppb(MW-9)to 87 ppb(MW-7) Tertiary butyl alcohol (TBA) was reported in seven of the twelve monitoring wells at concentrations ranging from 5 8 ppb(MW-1)to 76 ppb(MW-2) Di- isopropyl ether(DIPE)was reported in one well(MW-3) at 0 98 ppb Ethylene dibror ude(EDB) was detected in one well (MW-1)at 17 ppb 1,2-dichloroethane (1,2-DCA) was reported in seven of twelve monitoring wells at concentrations ranging from 0 89 ppb(MW-8)to 55 ppb(MW-3) Well MW-4 was not sampled due to an insufficient amount of water in the well Concentrations of benzene, toluene,ethylbenzene,and xylenes(BTEX) were detected in trip blank sample QCTB at 0 62 ppb,5 0 ppb,0 84 ppb,and 5 1 ppb,respectively Chemical concentrations were generally consistent with historical data Additionally,domestic well WSW and well DW-2 were sampled for TPHg,BTEX,MtBE,and other fuel oxygenates, all of which were reported as non-detectable above the method reporting limits The direction of groundwater flow within shallow wells (MW-1 through MW-10) was northwest to northeast,at a gradient ranging from 0 001 to 0 003 ft/ft The direction of groundwater flow within deep wells(DMW-1 through DMW-3) was to the southeast,at a gradient of 0 11 ft/ft Groundwater elevations in shallow monitoring wells MW- 1 through MW-7 increased by an average of 131 ft SECOR is performing granulated activated carbon treatment on well DW-1 Influent and effluent water samples are taken monthly and reported under separate cover in monthly performance summaries DW-2 and the onsite water supply well(WSW)are incorporated into the quarterly monitoring and reporting Analytical data from DW-2 is included in Tables 4 and 5 Certified laboratory analytical data are included in Attachment B This report presents our understanding of existing conditions at the subject site The conclusions contained herein are based on the analytical results,and professional judgment in accordance with current standards of professional practice,no other warranty is expressed or implied SECOR assumes no responsibility for exploratory borings or data reported by other consultants or contractors