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(§ 4.2) Any of the above land use could create environmental concerns that may be discovered in the future. This may be presumably from agricultural inputs, and will be discussed in the Conclusions Section of this report. z _w (§3.1) here is only one s�Theit m currently on the property, located at the referenced mobile home residential struct and schematic for this system are found�n P�ppenaix 4..� The schematic shows the system to exist of two - 100 foot leachlines and a 1,200 galm-96btictank on the east and south sides of the existing mobile home. Septic system design criteria for slopes do not have to e considered for any future system. (§3.4) The subject property is in the area designated as "High Water Table"by EHD's map denoting the various soil types and septic system requirements throughout the County. The Tracy area is known for its high water table, and since the property is in close proximity to the San Joaquin River, the water table is comparatively shallow. The standing water level (SWL) in the well at the new mobile home structure could not be measured because the well is more than 300 feet deep and is apparently perforated in a confined aquifer. However, from other projects completed by Chesney Consulting in this locale, namely the Douma Dairy -three miles to the south, the water table is known to be between 10 and 15 feet and can be even shallower closer to the San Joaquin River. The water table elevation is also heavily influenced by on-site and surrounding agricultural irrigation. (§3.2, 3.3, 3.4,3.5, and 3.6) A review of Application Permits on microfiche file at EHD reveals there has been one Application for Repairs/Additions/Replacements to septic systems within the one-half mile radius study area of Kasson and Critchett Roads exclusively. This repair occurred on �. Critchett Road. This low number of repair/additions can be attributed to the extremely low density housing within the study area. (§ 5.4) However, three miles to the south of the project at the San Joaquin Rimer,lys fi ivision, there have been many failures (50+) due to a combination of small-- van igh groundwater. These permits have not been included in this report due to the ss er c31 07 of paper. (§ 51 and 6.0) SOIL PROFILE AND PERCOLATION TESTING (§ 5.4) The USDA Soil Map shows the on-site soil structure to consist of three soil type classifications, as illustrated on the USDA Soil Map in Appendix 2. Capay clay (#121) at the southeastern half of the property, a small portion in the center of the property - Vernalis clay loam (#269), and at the northeast half of the property - Willows clay (#274). The Capay and Vernalis soils are silty-clays, clayey-silts, while the Willows soils are clay. These soils are moderately well- drained, and contrary to the above-referenced soil types, the percolation test results reveal the permeability to also be moderate, but generally slows with increased saturation. This moderate permeability was observed in all of the shallow perc test results, which is surprisingly indicative of almost all of the clay-type soils in the Tracy area. Sufficient soil "fines" exist within the encountered soil to impede very rapid percolation, which would occur with a sandy soil. There must be a five-foot separation distance between the soil-effluent interface and the depth to the water table, so that treatment of septic effluent can take place within the soil environment before reaching the water table. , Page -3- Chesney Consulting