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[6] CONCLUSIONS <br /> Since the present water table level is relatively shallow and has <br /> been at higher depths, maximum protection measures to the <br /> underlying groundwater should be engineered. These protection <br /> practices would include placement of the leach lines at a shallow <br /> depth to promote evaporation of effluent, designing the greatest <br /> amount of leach field area, and direct observation by the Engineer <br /> of Record of the proposed subsurface leach field area prior to <br /> leach line placement. <br /> Due to the agricultural nature of the subject property soils, most <br /> soil nitrogen can be found in the soil organic matter. This is <br /> particularly important since alfalfa is currently grown on the <br /> subject property. Alfalfa produces nitrogen through fixation, <br /> whereby atmospheric nitrogen is converted to an organic form to be <br /> utilized by the plant. Therefore, excess bio-manufactured nitrogen <br /> may be leached into the soil profile and ultimately into the <br /> groundwater. <br /> The nitrogen cycle in soils is highly complex. The subject <br /> property soils are conducive to two beneficial nitrogen cycle <br /> processes, namely denitrification and fixation of ammonium. <br /> Denitrification occurs under reduced oxygen supply, e.g. when water <br /> fills the soil voids and pores. With a clay soil structure, <br /> relatively less water is needed to create this saturated condition. <br /> Under these anaerobic conditions, nitrate nitrogen serves as an <br /> electron acceptor and is reduced to gaseous nitrogen forms. <br /> Fixation of ammonium occurs when the adsorption of ammonium <br /> molecules takes place between the expanding clay particles, which <br /> is the predominate soil type of the subject property. Ammonium is <br /> therefore unavailable for transformation to nitrate. <br /> 4 <br /> Inspection <br />