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n The infiltration tests were done at approximately 12 inches below the ground surface on the aforementioned plow pan layer. This depth represents a potential soil-effluent interface if the wastewater disposal system is installed at a high elevation in relation to the soil surface. The annular spaces were presaturated with 12 inches of water the day before testing. No soil cracking was observed in the soil surface. When the soil becomes saturated, infiltration slows considerably. This is evident on the Infiltration Test Form found in Appendix 4 in which there was an initial, large influx of water(500 cc 24 hours after pre-saturation), and then a steady decline of water infiltration after every 30 minutes. The double ring infiltration test results are summarized below: TABLE 4 . 'Y�,_,,4NFILTRATION:1 EST RESULTS` - IINFILTRATION RATE IN CM/HR,CM/SEC AND MINAN r 1.79 cm/hr, 0.000497 cm/sec, 85.1 min/in 2.4 Soil Chemical Test Results Chemical analytical assessment of the subsurface soils was done on the samples at the respective depths,retrieved from the two 15 ft.perc test borings. The test results are noted on the Soil Analysis Reports in Appendix 5. This chemistry was done to analyze the primary constituents that influence nitrate loading; specifically adsorption, nitrification and denitrification. The important soil parameters for nitrate assessment are the organic matter,pH, cation exchange capacity(CEC),and indigenous nitrate-nitrogen content. As noted from the test results,the organic matter within the soil profile is low. Thenitrate-nitrogen contents low-to-low consistent nitrogen concentration throughout the soil profile in the NEC at an averaC of 4.5 pp (does not exceed 10 ppm as NO,-N). The SWC soil tests show a higher nitrate-nitrogen concentratiddn through soil profile in comparison to the NEC samples at approxi telt'2x fortlie and 5 ft test samples, an proximately 3.5x for the 10 ft and 15 ft samples. Although eq i g soil nitrate-ni ,{egen ontent vados water content is difficult,the nitrogen cone trafion in the SWC t 9 ppm11111 ppm, 9 pp an pp ay indicat the possibility that greater than 10 p NO,-N�ould exist in e vad9he zone w t ese concen ations c considered low-to-medium for soils t tt have-Keen under past agn ultiival pra'c ces. Since septic tank effluent is composed predominately of ammonium(NH,),the pH, along with the CEC,have influence on ammonium molecules. The pH of the soil profile is alkaline with all samples above 8.0,except for the 10 ft depth in the SWC test area,which had a pH of 7.9(and the highest N0,-N content at 19 ppm). This pH i profile may have a defined suppression effect on nitrate formation(nitrification)by affecting molecular ammonium stability. Secondly,nitrate that does form,alkaline environments may increase the potential for denitrification. The CEC measures the ability of the soil to theoretically trap and hold ammonium molecules, thus having an influence on suppression of nitrification;however, from the test results,there appears to be little correlation between CEC and nitrogen concentration. Given that the SWC soils of the disposal area have a higher nitrate-nitrogen concentration than the NEC soils,it is theorized that these concentrations throughout the SWC soil profile may be much greater that what was observed if the referenced soil parameters that influence, and may suppress nitrification were not occurring. The following Table illustrates and summarizes the encountered soil profile characteristics,along with the analytical test results for comparison purposes: Page -9- Chesney Consulting