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(§ 7.0) CONCLUSIONS Although there is no proposal to build on either of the proposed Parcels from this subdivision, the perc test results for proposed Parcel 2 shows acceptable percolation for the management of septic system effluent flows at typical leachline depth. As noted from the perc test results, as the soil becomes increasingly saturated, the percolation rate decreases substantially. The two deeper perc tests representative of sumps were conducted at this depth to demonstrate that unacceptable permeability exists at sump depth due to the severe hardpan encountered. The perc test results for Parcel 1 show that percolation began at a comparatively fast rate, then what appears to be either vadose zone water intrusion, or partial cave-in of the boring, caused the water level to rise. This resulted in perc test failure conditions. Distribution of septic effluent at shallower depths is always preferable than at deeper depths typical of seepage pits. Given, however, that this is a seepage pit area, EHD would allow, and may prefer the installation of seepage pits due to lifespan concerns. In comparison to sumps, the lifespan of seepage pits can be significantly greater in most cases. 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 in leachlines and 10 ft in sumps and seepage pits. Therefore, there is more than sufficient distance existing between the bottom of a maximum depth seepage pit at 25 ft in depth, and the current groundwater depth of approximately 90 ft. (§ 6.8) As referenced, although there s o pr osal to build on the Parcels at present, a septic system for any future development will pendent upon the number of bedrooms a new house structure will have. Determinatioof a bedroom is made by closets. If a room has a closet,_10i designated as a bedroom. In a dtl ition, a registered civil engineer must design a septic system for the property if passing perc rates re not obtained in a future leachfield location. (§ 6.7) No problems are anticipated for the existing septic systems and any future septic system on the Parcels, other than typical lifespan concerns. It is important to recognize that all septic systems have a lifespan, which is dependent 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 very fine sands, silts, and clays, anaerobic conditions may prevail over time which may decrease the expectant life of any on-site septic system. 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 rainy season, subsurface soil moisture content will increase, thus decreasing permeability. Page -6-