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E (§ 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 1 shows acceptable percolation for the management of any future septic system effluent flows attypical leachline and sump depths. As noted from the perc test results, as the soil becomes increasingly saturated, the percolation rate potential decreases to a measurable,but not substantial extent. The deeper perc test representative of sumps was conducted at this depth to demonstrate that acceptable permeability exists at this depth. The perc test results show that percolation started off at a comparatively slower rate, then accelerated, and then finished near the initial perc rates. This phenomenon has been observed before and may be attributed to soil hydrodynamics: As the water begins to work its way through the micro and macroscopic soil pores, individual water molecules increasingly "pull"themselves through these channels under gravitational influence. Given the proximity to the Calaveras River, shallow septic system structures like sumps should be considered for any future installation. Distribution of septic effluent at shallower depths is almost ` h that this is a always preferable than at deeper depths typical of seepage pits. Given, however, 1 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. A filter bed area can be calculated if so desired, but this is not recommended in this locale. 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 feet in sumps and seepage pits. Therefore,there is more than sufficient distance existing between the bottom of a maximum depth sump at 12 feet in depth, and the current groundwater depth of 125 feet. (§ 6.$) As referenced, although there is no proposal to build on the Parcels, a septic system for any future development will be dependent upon the number of bedrooms within a new house. Determination of a bedroom is made by closets. If a room has a closet, it is designated as a bedroom. (§6.7) No problems are anticipated for any future septic system on the Parcels, other than typical lifespan concerns. An engineered septic system will not have to be installed for this project unless there are perc test failures, or septic system failures. Any 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 areas. Any new septic system structures for the property must comply with the "distance" requirements from property borders, roads, wells, irrigation lines, etc. As referenced, the surrounding cherry orchard is irrigated by micro-sprinklers, so there should be no inundation concerns as may be the case with flood irrigation. 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. Page -5- Chesney Consulting