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f SITE CONCEPTUAL MODEL WATER TABLE ELEVATIONS AND GRADIENT The water table vanes from 34'to 49'below the ground surface The prominent hydraulic gradient is s= 006 bearing to the East with droughts having a gradient of s= 009 bearing to the East Past monitoring events shows that the flow can also go North with a gradient of s= 003 SOIL BORING SAMPLE ANALYSIS FINDINGS The soil samples from the monitoring well borings indicate the contaminated soil is limited to the soil under the existing building The borings under the two tanks (BH-1, and MWA) show contamination clinging to the soil particles BH#1 showed TPHg from 1,000 to 6,800ppm the whole length BTEX compounds were spotty for 1311#1 Benzene, and Toluene are limited to the sand lense at the 35'depth with concentrations of 0.351 and 177ppm,respectively Ethyl Benzene appears at the top and at the bottom with concentrations ranging from ND to 32.5ppm Total Xylene was present the length of the bore with concentrations ranging from 10 to 572ppm The bore for MW-1 shows TPHg and BTEX only in the top 30'. Benzene at 1 8ppm, Toluene at 261 ppm, Ethyl Benzene at 22 8ppm, Total Xylene at 1,540ppm,and TPHg at 12,300ppm The soil samples from MW-2,MW-3,MW-4,and MW-5 came back remarkably clean A summary of results for soil samples is attached WATER SAMPLE ANALYSIS FINDINGS The analytical results for water samples has shown consistent positives for BTEX compounds, TPHg,Chloroform, 1,2-Dichlorobenzene, I,2-Dxchloroethane(1,2-DCA),cis-1,2-Dichloroethene, Tetrachloroethene, Trichloroethene(TCI .), and Vinyl Chloride A summary of water samples from the initial well drilling and monitoring events is attached. MAXIMUM CONTAMINANT LEVELS For the above listed consistent positive results the EPA has published Maximum Contaminant Levels (MCL's) for primary health concerns They are as follows Compound MCL.ppb Wells that exceed MCL's as of 9115104 Benzene 50 MW-3S(1 1.6) Toluene 1,0000 None Ethyl Benzene 7000 None Xylene 10,000.0 None TPHg 210* MW-3S(542) Chloroform Not Regulated None 1,2-Dichlorobenzene Not Regulated None 1,2-Dichloroethane(DCA) 50 MW-3S(6.9), MW-5S(9 8), MW-5D(37) cis-1,2-Dichloroethene 700 None Tetrachloroethene 50 None Tnchloroethene(TCE) 50 None Vinyl Chloride 20 None # from State Regional Water Quality Control Board 2