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�.. v../ and the new domestic well must comply with the published "distance" requirements from property borders, roads, and especially irrigation fields and irrigation ditches, etc. As referenced, the perc test for parcel 3 was conducted 168 feet north of the Westside Irrigation canal. The new well must be 50 feet north of the irrigation canal and the leachfield must be 150 feet from the well. As can be noted on the Tentative Map, there is ample area within parcel 3 for all distance requirements to be achieved. The existing concrete wellhead for the domestic well on parcel 2 is cracked. As of August 15, 2003, the well casing had been extended and the cracks in the concrete have been filled with epoxy in compliance with EHD requirements. A new concrete wellhead will be poured over the existing one. It is important to note that all septic systems have a lifespan. This lifespan is dependant on several factors and is therefore difficult to determine. Although only one repair and addition were found at the Environmental Health Department within this locale, septic systems in this area will have a lifespan due to the indigenous fine-grained soils. However, from the operation of the Mattos's septic system, it appears this lifespan may be a long time. Septic system leachline failure would primarily result from the advanced formation of a "biomat" or "clogging mat" on the wetted soil/effluent 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. Since the shallow subsurface soils consist of a figgLZEauWJ%A,. te.;W1, anaerob c„ 'QW will prevail over time which may hasten leachfield failure. However, if the leachlines are i si„�tnlledd high in elev n there will be a greater opportunity for oxygen intrusion fromhe atUW,%kwj_r, thus theorgfically assisting in biomatdie rradation. As noted on the Leachline Requirement Map published by the Environmental Health Department, the subject property is in the "High Water Table Areas." The map shows that sumps or seepage pits are not allowed in this area. The nitrate concentrations determined in the underlying groundwater suggests there has been impact to the shallower aquifers predominately from upgradient agricultural inputs. There is a neighbors' septic system to the south of the tested well; however, influences from this septic system is unlikely since it can be considered cross gradient to the groundwater directional flow. As noted above, housing subdivisions will eventually be built on the subject parcels. Structures, concrete and asphalt may have an attenuating effect on the downward migration of nitrate currently in transit. Unfortunately, unregulated lawn and garden nitrogen fertilization has the potential to actually increase the nitrate loading from a housing subdivision on sewer. Regardless of the nitrate concentration of any well water in rural areas, it is recommended that bottled water should always be used for drinking and cooking purposes. The Mattos' do use bottled water for these purposes. Page -4- Ckestwy Consufting