1983-08-01 Septic System Design Report

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5 ! ! TOM SMITH ASSOCIATES Inc Consulting Engineers August 1, 1983 IncAnderson Builders 3911 Lcslee Curve Excelsior, I'iK 55331 ATTN: Keith Anderson AU6-2Be3 OF ORONQ SUBJECT: Evaluation and report for onsite setiage treatment system, I-Iaass Residence, flaxwell Day, Orono, lH! Job // 1979 Per your request we have condicted a site evaluation for the above subject site# This report presents our findings, recommendations, and desigi specifications for the sewage treatment for this site# CODCLUSIONS AND PJSCO.DSTDATIONS; The depth to seasonally high ground water table, as indicated by mottling of the soil samples recovered, is betvreen 3 to u feet belov; existinr. grade. The percolation rate of the soils above this are on the order of 20 minutes per inch. Even considering minimum depth of rock under normal distribution lines in a standard drainfield, the site would have to receive some fill in order to maintain at least 3 feet between the bottom of the drainfield rock and the seasonally hi£^i ground water table. At any configuration, the topography of the site would not allow total gravity flow of the system , and some pumping would have to be incorporated# Given these conditions and the size of the drainfield required, "we recommend the onsite sev/age treatment system at this site incorporate a mound type system in accordance with the attached specifications# The mound system, and in fact even a standard drain tile system co\ild be accomodated in the area we discussed on the site, however either would have to extend to the south sufficiently far to be vrell within the drip line of the mature maple trees immediately east of the proposed new house. In order to avoid any possible damage to these trees from construction of the system, and to mo\.’-s the treatment area out of the swale in that particular location, wo recommend moving the treatment to the north of the site v:e discussed, just beyond the small grove of evergreen trees where open conditions exist. This area is shovm on the attached sketch, and was tested id-th boring B-2 and percolation tests P-!^, P-5> and P-6# EVALUATION; The site in question is relatively level with bordering groves of very mature trees. The lot width is 282 feet in the east-west dimension which fronts on the lake, and is a total of approximately 8 acres# The areas tested were grassy and fairly open. The attached sketch shows the areas tested and nearby features of interest, along with contour lines# A total of four soil test borings ircre put down on July 28th, and six percolation tests were set up to soak on July 28th and then run off of July 29th# The soils vrere predominately silty and lean claj^s, llottling, an indication of 5109 Kimberly Road, Minnetonka, Minnesota 55343 16121 934-8031