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F L PHYSICAL CHARACTERISTICS AND ANALYTICAL TEST RESULTS site consists of level terrain; consequently,there will have to be no septic system derations for slopes. An 16 ft hand boring was completed in the stormwater detention basin located at the east end of the Cunha Trucking facility. This facility is located to the southeast of the subject property. Since the detention basin is six feet deep, this boring was actually terminated at 22 feet below existing surrounding grade. A log of boring found in the Appendix illustrates the subsurface soil characteristics found in this boring. The surface soils (04) are composed of a fine silty sand. From six to nine feet,there exists a medium well-graded sand with rust mottling. From 10 to 16 feet, there is a clayey silt, also with some rust mottling. Below this clayey silt layer, there is a medium sand extending to a coarse sand from 16 to 19 feet. From 19 to 22 feet there is another clayey silt/silty clay layer. This strata was wet and can be considered to be the capillary fringe. The boring was terminated at this elevation. A feature of the soil observed in this boring was rust mottling of the silty sand strata. This can be attributed to geologic processes whereby the mottling originates from seasonal soil saturation. As the water encounters strata of slower permeability, the percolating water "pools" on the top of the slower permeability layer. This creates an anaerobic zone. Rust mottling occurs when anaerobic bacteria decompose organic matter and use oxidized iron in their metabolic processes. If these two conditions are present-organic matter and an anaerobic environment, denitrification (the conversion of nitrate to gaseous products and the primary means by which nitrate concentrations are reduced) is promoted. Two soil samples were obtained from near the anticipated leachfield and one from the boring termination elevation of 22 feet below existing grade. As the noted on the attached SOIL ANALYSIS REPORT,the nitrate concentration at the 22 ft elevation is 3 ppm and actually higher than the surface soils. This higher concentration can be attributed to the downward migration of nitrate molecules over the centuries. However, the concentration is low which may be indicative of the above-referenced silt strata promoting denitrification. Chemical analyses of soil composited from the 32 to 42 inch depth(36 in. avg.) from the anticipated leachfield area was done to quantify several constituents. The important parameters for nitrate loading assessment are the organic matter, pH, cation exchange capacity (CEC), and nitrate-nitrogen(NO3-N) content. As noted,the organic matter in the soil is low and indicates a potentially small influence on additional nitrate-nitrogen loading in the future. Previous organic matter content from past agricultural activity has apparently been oxidized. The pH of the soil is alkaline which may slightly inhibit ammonium(NH4) formation and stability. The CEC measures the ability of the soil to theoretically trap and hold ammonium molecules. A CEC of 10.2 indicates there is limited potential for the retention of ammonium molecules for microbial uptake. The nitrate-nitrogen concentration is very low at 1 ppm. 2 Vafley Ag Research