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• a Y � 1 I� <br /> 2. ANALYSES OF SELECTED DOMESTIC WELLS <br /> Seven operational and accessible domestic wells were sampled around the subject property to <br /> quantify nitrate concentrations. The Maximum Contaminant Level (MCL) for nitrate (as NO3) <br /> is 45 ppm and the MCL for DBCP is 0.0002 ppm or 0.2 ,ug/L. Documentation at PHS-EHD <br /> indicates there has been serious nitrate impact originating from the Southland Mobile Home <br /> Park, which is directly west and cross-gradient from the subject site. Two wells sampled on the <br /> Highway 99 Frontage Road, which are downgradient from the Southland Mobile Home Park <br /> reveal well water over the MCL for nitrate. The single family residence (SFR) at 15393 Cottage <br /> also tested for a nitrate level slightly over the MCL at 47 ppm. This nitrate concentration is <br /> presumably originating from the high density septic systems within this area. The remaining <br /> wellstested are below the MCL. <br /> The water test results have been plotted on a United States Geological Survey Map. A summary <br /> of the water well test results are as follows: <br /> NITRATE AND DBCP .CONCENTRATIONS . <br /> ADDRESS NITRATE CONC. DBCP CONC. T 4 <br /> +15655 S.Mitchell Road 9 ppm as NO3 N/A <br /> +15444 S. Mitchell Road 18 ppm as NO, BDL* 1 <br /> 8092 Southland Road 18 ppm as NO, N/A <br /> Lathrop Road Offramp 29 ppm as NO, NIA <br /> 15393 Cottage Avenue 47 ppm as NO3 N/A <br /> 15257 S. Hwy 99(Frontage) 53 ppm as NO, N/A - <br /> 15141 S. Hwy 99 (Frontage) 58 ppm as NO, N/A <br /> +Well Log Available <br /> *Below Detection Limits <br /> B. SURFACE WATER INFORMATION <br /> Surface water consists of all water sources originating from the surface of the project. These <br /> sources include rainfall runoff, domestic irrigation and stormwater retention. The San Joaquin <br /> County of Public Works - Isohyetal Map indicate 11 inches of rainfall to be the Mean Annual <br /> Precipitation in the area of the project. Stormwater runoff retention will be accomplished by a <br /> channel fronting Mitchell Road. <br /> After project development, a percentage of the land surface area will be impermeably covered <br /> with structures, concrete and/or asphalt. This will have an attenuating effect on the downward <br /> migration of nitrate molecules currently "in-transit" and on nitrate yet to be formed. <br /> 6 <br /> Vafley Ag Research <br />