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File No. CO-9024-SO1 <br /> September 25, 1991 <br /> The percolation tests were performed by drilling a 12-inch diameter hole to a depth of 36 <br /> inches at both locations. The sides of the holes were scored and loose soils were removed from <br /> the bottom of the hole by hand. The bottom of the holes were filled with a 2-inch layer of gravel <br /> and a perforated 4-inch diameter PVC pipe installed. The annular space between the pipe and <br /> hole sides was backfilled with gravel for some distance above the base of the hole to sturdy the <br /> PVC pipe. A minimum of 12-inches of water above the gravel base was added and allowed to soak <br /> for 24 hours. The percolation tests were then performed. <br /> A copy of the actual data sheet associated with each percolation test is included in Appendix A of <br /> this report. The percolation test results obtained are summarized below. <br /> Test Depth Percolation Rate' <br /> Hole Parcel (inches) (min/in) Comments <br /> 1 2 36 1 5 Proposed leach field <br /> 2 1 36 Existing leach field <br /> The highest percolation rate allowed for leach line fields is 60 min/in and 30 min/in for <br /> seepage pits (without alternate septic system design by a registered engineer). It can be seen <br /> from the test results reported above that Parcel 2 meets this criteria while Parcel 1 does not. <br /> A deeper percolation test could be performed on Parcel 1. However, this was considered <br /> unnecessary due to the successful performance of the existing system on Parcel 1 and the recent <br /> satisfactory inspection report for this septic system. <br /> Conclusions <br /> Based on the results of the percolation tests, soil profile, past performance of the existing <br /> system on Parcel 1, inspection report for the system on Parcel 1, EHD permit records of other <br /> systems in the site vicinity, and on interviews of neighbors we have formed the following <br /> opinions. <br /> The existing septic system on Parcel 1 can be expected to continue to give good performance. <br /> Due to the surface clay layer, the disposal field for Parcel 2 should include seepage pits. Since <br /> the maximum allowable depth of seepage pits is 25 feet and the groundwater table is at a depth of <br /> approximately 70 feet, both the existing and proposed septic systems should not adversely affect <br /> the quality of the groundwater in the area. <br /> 3 <br />