SR0084880_SSS - Laserfiche WebLink

Home Browse Search

The data illustrates the average daily flow (ADF) is less than 10,000 gpd. In addition, the average daily water usage also incorporates landscape irrigation, thus lowering the wastewater flow volume totals to an indeterminable amount. EFFLUENT DISPOSAL AREAS AND STRUCTURES The second issue to be investigated was delineation of the existing primary effluent disposal areas. Found in Appendix D, are diagrams of the primary disposal areas. There are 21 seepage pits located adjacent to the north of the Nottingham Treatment System, as illustrated on APN 051-150-14. Additionally, there are eight seepage pits located on APN 051-150-27, on the north side of the fence that separates the two subject APNs. Also located on Parcel 27 are three 100 ft leachlines, each with one 48" x 25 ft deep seepage pits at the ends of the leachline. RESERVE/REPLACEMENT AREAS As illustrated in the aerial photo in Appendix E, the reserve/replacement areas are denoted on Parcel 151-115-27. The following calculations only pertain to the existing leachlines with connected seepage pits and future leachlines and seepage pits to be potentially installed. The area immediately east of the pond can be used for leachlines, while the square area at the north end of the leachlines can be used for seepage pits. This square area is approximately 90 ft x 90 ft. Accounting for property line and distance between pit setbacks, this square area can have installed: 6 x 6 pits = 36 seepage pits. Section 9.9.7 of the SJC OWTS Standards specifies that "Two seepage pits are permitted at the terminal end of a leach line and that additional seepage pits may be permitted in hardpan/clay soils, or as determined by the EHD Director, with a minimum of 20% of the dispersal field in leach line being maintained." From the perc test results, it is evident that leachlines are theoretically having minimal management of effluent flows. If ultimately six leachlines are installed and ultimately a total of 36 pits + 3 existing pits + 3 proposed pits = 42 pits, then based on total infiltrative area, we find: Leachlines = 600 LFLL x 4 ft2 = 2,400 ft2 of infiltrative surface. Seepage pits = 42 pits x 276 ft2 = 11,592 ft2 o£ infiltrative surface. Total dispersal area = 2,400 + 11,592 = 13,993 ft2 x 20% = 2,798 ft2 > 2,400 ft2 On the west side of the pond is an area of 2,350 ft2, which can also be used for effluent disposal that could consist of two - 100 ft leachlines (installed end-to-end with seepage pits). Effluent will have to be pumped to this location (a duplex pump system exists). The calculations are now: Leachlines = 800 LFLL x 4 ft2 = 3,200 ft2 of infiltrative surface. Seepage pits = 42 pits + 2 pits = 44 pits x 276 ft' 12,144 ft2 of infiltrative surface. Total dispersal area = 3,200 + 12,144 = 15,344 ft2 x 20% = 3,068 ft2 < 3,200 W. Page -2- Chesney Consulting