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%001 .,i 161 CONCLUSIONS The soil structure found in the areas of the future leachfields has been under irrigated forage and grain crops for the last several years. The soil characteristics will undoubtedly change in the leachfield areas, after the introduction of sewage effluent. This will be due to the absence of crops being grown in these areas and different biological processes taking over after the soil becomes a sewage drainfield. Since these soil changes are anticipated, this is the reasoning behind the recommendation of 12,000 square foot leachfield areas with 50% standby replacement areas for both parcels. This recommended area will help ensure stability and guard against leachfield failure since the soil structure contains a high percentage of clay. A leachfield failure would primarily result from the formation of a "biomat" or 'clogging mat" on the wetted interface where the effluent enters the soil. 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. At present, the subject soil can be considered aerobic due to the alfalfa/grain root systems. However, over time and with the loss of these crops in the leachfield areas, these soils may eventually become anaerobic and therefore, more susceptible to clogging mat formation and potential failure. As an additional protection measure, seepage pits will have to be incorporated into the septic system design for both parcels. The number and dimensions of seepage pits will be dependant upon the number of bedrooms the houses will have, and the number of anticipated people that will occupy the houses, particularly children. With respect to the protection of the underlying groundwater from pathogens and primarily nitrates (NOA the soil structure of the subject parcels can be considered favorable for prevention of contamination from these two sources. The Littlejohns Creek must be protected from impact by sewage effluent. Surfacing of effluent may be a slight possibility during a highly unusual rainfall event of long duration and intensity. Protection measures to prevent surface or subsurface effluent from entering the creek must be followed. Normally, the distance requirements as promulgated in the County Codes are sufficient. All related development structures such as wells, etc. must comply with these published distance requirements from the septic systems. El 0 *- ity ontml 1 -T -d—