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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. Therefore, sufficient distance exists between the bottom of a maximum depth leachline trench at 42 inches (although a filter bed will be installed which should be higher in elevation) and the current groundwater depth f of greater than 12 feet (144 inches), as evidenced by the backhoe test pit: (144 inches minus 42 inches = 102 inches= 8.5 feet). /(§ 6.8) The number of leachlines and septic tank size will be dependent upon the number of bedrooms within the new house. Leachline length in this locale is stipulated by EHD to be 100 feet for each bedroom. Determination of a bedroom is made by closets. If a room has a closet, it is designated as a bedroom. From the total lateral length of leachline, the filter bed area can be calculated. ,//(§ 6.7) No problems are anticipated for any future septic system on the Parcel, other than typical lifespan concerns. An engineered septic system will not have to be installed for this project unless there are continual failures. The new system must have at least a 50% standby replacement area incorporated into the design,which will be easily achieved due to the surrounding open area on Parcel 1. All related septic system structures and the new domestic well for the Parcel must comply with the "distance" requirements from property borders, roads, and irrigation ditches, etc. As referenced, the future surrounding vineyard will be drip-irrigated, so there should be no inundation concerns. 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 fine sands, silts and clays, aerobic conditions may prevail over time which may increase the expectant life of the new filter bed. Lifespan will be dependant upon the efficiency of the bed to manage effluent flows. By nature of the construction details of a filter bed, it will be installed high in elevation, consequently, there will be a greater opportunity for oxygen intrusion from the atmosphere. This will theoretically assist 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 under agricultural production, it is highly recommended that bottled water be used for drinking and cooking purposes. It is my understanding that the Stokes' use bottled water for these purposes. Page-6- Chesney Consulting