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To determine the extent of nitrate impact to the underlying water table, three water samples were taken: The first sample was retrieved from the northeast corner of the proposed filter bed. This is denoted on the attached WATER ANALYSIS REPORT as "Water Table." Test results indicate a high concentrations of nitrate and chloride at 106 mg/L and 167 nig/L, respectively. Studies have found that septic systems contribute chloride to groundwater. Chloride travels as readily, if not more so, than nitrate in the vadose and phreatic (saturated) zones and can be the first indicator of septic contamination. The chloride concentrations in most groundwater formations averages 6 mg/1. The typical concentration of chlorides in untreated domestic wastewater is 50 mg/l, with the range being 30-100 mg/1. The second sample was taken from the northeast corner of the existing leachfield (Sample Number `ELF"). Test results indicate very high concentrations of nitrate and chloride at 259 mg/L and 213 mg/L, respectively. Due to this high nitrate concentration downgradient from the existing leachfield, it was decided to test the water table upgradient to this disposal area. Nitrate test results reveal a concentration of 56 ppm as nitrate, indicating impact from the current system. The nitrate concentration in the sampled well is above the median value of 22.5 ppm N031 at 40 ppm, as nitrate. The Maximum Contaminant Level (MCL) for nitrate (NO3) in drinking water is 45 ppm. Chloride was tested at 200 mg/L. When interpreted together, the two test results for nitrate and chloride are a more positive indicator of septic influence than nitrate alone. UNDERLYING GROUNDWATER ANALYSIS EABLE UNDER PROPOSED NEW WATER TABLE UNDER EXISTINGESSURIZED FILTER BED GRAVITY LEACHFIELD ANALYTE LEVEL FOUND ANALYTE LEVEL FOUND Nitrate 106 mg/L Nitrate(As Nitrate) 259 mg/L (56 mg/L upgradient of the leadifield) Total Dissolved Solids 1360 mg/L Total Dissolved Solids 1630 mg/L pH 7.4 pH 7.0 Total Alkalinity 444 mg/L Total Alkalinity 691 mg/L Calculation of Alkalinity Requirement for Nitrification All of the nitrate-nitrogen loading calculations below are contingent upon the environmental factors required for nitrification to occur. These conditions include soil pore-space oxygen content, soil temperature, pH, electrical conductivity, organic matter, cation exchange capacity, and alkalinity. Alkalinity in wastewater effluent is derived from the domestic water supply in addition to the introduction of wastes. As referenced,nitrification consumes approximately 7.1 mg of alkalinity for every mg of ammonia-nitrogen (NH4-N) oxidized. 5 Chesney Consulting