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h _1_100 - — - [5] CONCLUSIONS - The perc test result for the subject Parcel suggests there will be excellent effluent percolation at the slow leachline depth of 40-42 inches throughout the leach-field area: This was evidenced by the hal two perc tests performed on either side'of this area with.very similar results. The perc tests show l =:J that percolative capacity does not necessarily decrease.with`soil saturation, but is somewhat t. - influenced by head pressure.= - a 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. From the number of repairs and additions within the _ area,it is evident thatsepticsystem failure with_ in the shallow soils is a possibility. Since the septic system will have a lifespan,it is recommended that a financial"sinking fund"be initially established to assist in paying for a possible repair/replacement. Septic system 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 higher porosity soil material,aerobic conditions will probably prevail overtime which may prevent leachline failure. - r Tli Leachline Requirement map published by the Environinental Health Department indicates the subject property is in the High Water Table Area, and that-seepage pits,are not allowed in this area. ri From our observations,'the leachfield soils have readily.-coiripactable'properties-under optimum - moisture conditions. 'Therefore, asstated in-the Development Title, Section 9-1110.4(c)(5): The leachfield area will be barricaded so it cannot be driven over;parked on, or used as a storage area. The leachfield area must be used for that specific purpose only and cannot contain any underground - utility lines. As referenced above, the leachfield must be hydraulically protected during the rainy season to prevent inundation. . If several people will be_ using the system,that is higher than originally estimated, consideration should be giver: to eventually over-sizing the septic system to accommodate additional wastewater flows. This may include the addition of sumps,but will depend upon PHS-EHD•discretion. A 100%standby replacement area to the west of the existing leachfield can be used for repair or addition: All related septic system. structures must:comply with the - published "distance".requirements from property borders,�roads, irrigation fields, etc. - j The upper nitrate concentrations found-in the underlying groundwater indicates there has been - nitrate impact to the underlying aquifer(s). ::This may be attributable to the obvious porosity of the fine-grained soils throughout the soil profile which may expediting the downward migration of . nitrate molecules. There appears to have been sufficient_fines within the soil matrix to theoretically -_ - promote denitrification.: Regardless of the nitrate concentration of any well water id rural areas,.it is recommended'fl at bottled water should always be used for drinking and cooking.purposes. = _ Page =4- - - _ 7Ja. Y AY Research