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EHD requires that there be sufficient distance for"treatment" of septic effluent before it encounters the groundwater table. This distance is normally regarded to be five feet for leachlines and ten feet for sumps and seepage pits. Therefore, sufficient distance exists between the bottom of a maximum depth seepage pit of 25 feet and the current groundwater depth of approximately 55 feet. (§ 6.8) TJ a number of leachlines and septic tank size is unknown for the future residential structure since there is osal to build on any of the proposed Parcels. (§ 6. o:problems are nticipated for any future septic system on the property, other than typical lifesp neered septic systems will not have to be installed for this proposed subdivision unless there are continual failures. Each new system must have at least a 50% standby replacement area incorporated into the design of the septic system, which can easily be achieved. All related septic system structures and the new domestic well must comply with the "distance" requirements from property borders, roads, wells, irrigation fields, irrigation ditches, the Lone Tree Creek, etc. It is important to recognize that all septic systems have a lifespan, which is dependant on several factors and is therefore difficult to determine. 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 on the property consist of silts and sands, aerobic conditions may prevail over time which may increase the expectant life of any new leachfield. Lifespan will be partly dependant upon the efficiency of the leachline trench structures and seepage pits to manage effluent flows. If the leachlines are installed high in elevation, there will be a greater opportunity for oxygen intrusion from the atmosphere, thus theoretically assisting in biomat degradation, along with promoting evapotranspiration. In addition, soil moisture content of the subsurface soils will play an important role in septic system operational capacity. For example, if heavy rains are experienced in any given winter, subsurface soil moisture content will increase, thus decreasing permeability. In unsewered areas and/or areas that have been, or currently are in or near agricultural production, it is highly recommended that bottled water be used for drinking and cooking purposes. This is particularly important given the on-site well water analyses indicate high nitrate and DBCP concentrations. Page-7- Chesney Consulting