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[7] CONCLUSIONS The results of the percolation tests indicate there is rapid percolation in the shallow, 42 inch boring in the proposed area of the leachfield, even considering the saturated soil conditions after the recent rains. This 42 inch depth represents the maximum depth for leachline trenches. As referenced in Section 4, there are two methods of design of the leachfield. It is our recommendation that due to the high groundwater table and potential for dramatic fluctuations, leachlines be used exclusively, with no sumps. This septic system design allows for maximum soil/effluent interaction to attenuate potential pathogen contamination. Using leachlines exclusively may assist in environmental stability from pathogen contamination, i although the possibility for leachfield failure does exist. This is the reason for having the 100% replacement area. A failure would primarily result from the formation of a "biomat" or "clogging _ mat" on the wetted soil interface. This mat is composed mostly of aerobic and anaerobic bacteria and bacterial products consisting of a slime of polyuronides and polysaccharides. If the soil/effluent interface is well aerated, a variety of soil microfauna such as nematodes and protozoa may digest the clogging mat bacteria. The subject area soil can be considered aerobic due to its sandy structure. Although there may be a propensity for aerobic degradation of the biomat,the soil structure is also conducive for nitrate formation. The soil of the subject property can be considered favorable for nitrification. The nitrogen cycle and the eventual formation of nitrates is highly complex within the soil environment. The subject parcel soils are not conducive for two beneficial nitrogen cycle processes, namely fixation of ammonium and denitrification. Fixation of ammonium (NH4) can occur with the adsorption of ammonium molecules onto expanding clay particles. Insufficient clay exists within the subject parcel soil profile to attenuate nitrate formation. With adsorption, ammonium becomes "fixed" and is unavailable for biological transformation to nitrate. Denitrification occurs under reduced oxygen supply or anaerobic conditions. This happens when water or effluent fills the soil pores. The sandy soil structure is not favorable for extended saturation to create an anaerobic environment, thus promoting denitrification. Therefore, the possibility exists for some contribution of nitrate to the underlying groundwater. However, since the number of employees at the subject facility is relatively small at four, yearly nitrate nitrogen contribution to the groundwater is comparative to small-scale agricultural .. practices in the area. �� uality (Yontrol Inspection js