SU0005971 SSNL - Laserfiche WebLink

Home Browse Search

Test Soil Test Hole Percolation SJCEHD Number Description Depth ft. Rate min./inch Observed P-12 Clayey 4.9 50 Yes Gravelly and P-13 Sandy Clay 3 Did Not Perc Yes P-14 Sandy Clayey 5.2 Did Not Perc Yes Silt P-15 Clayey Sand 3.2 Did Not Perc Yes P-16 I Clayey Sand 4.4 Did Not Perc Yes S. CONCLUSIONS The results of our percolation tests indicate that a suitable soil percolation straturrl only exists only on the proposed parcel 2 (east parcel split from APN 009-170-04) at the shallow percolation test location at the depth tested and was observed by a representative of SJCEHD. A suitable soil condition is defined as a stratum capable of percolating water at a rate of 60 min/inch or faster at shallow depths and 30 minlinch for deep tests. It is our professional opinion that a conventional septic tank/leach trench sewage disposal system designed per SJCEHD criteria could theoretically adequately serve a proposed residence on the proposed parcel 2. However, it should be recognized that only one percolation test passed out of the sixteen tests performed in the area. Due to the cemented and fine grained subsurface soils encountered and the failed percolation tests, which were not observed by a representative of SJCEHD, it is our opinion that if any future residence were constructed on parcel 2, additional percolation tests should be performed in the actual area of the proposed leach field. The results of our percolation tests performed on proposed parcels 1, 3, and 4 indicate that a suitable soil percolation stratum does not exist, at least at the percolation test locations at the depths tested. In our opinion this is due to the fine grained and cemented nature of the soils encountered. As previously stated, a suitable soil condition is defined as a stratum capable of percolating water at a rate of 60 min/inch or faster at shallow depths and 30 min/inch for deep tests. Based on these results, it is our professional opinion that a conventional septic tank/leach trench sewage disposal system designed per SJCEHD criteria would not adequately serve any residences that would ever be built on the proposed parcels 1, 3, and 4 and that there is a need for an engineered system. We understand that currently no development is proposed at the project site, however, we recommend that if future development takes place, homeowners be made aware of the difficult percolation characteristics of the near surface soils at the site. As previously mentioned, there was no concentration of DBCP found in detectable amounts in the groundwater sampled at the project site. 575.56.GOt/ST05R687R August'25,2005 -2005 Kleinrolder, Inc. Page 5 of 5