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HomeMy WebLinkAbout1987-01-12 Site Evaluation ReportHakanson Anderson As-, :., Inc. January 12, 1987 Mr. David Nitz 950 Red Sandstone Road, #41 Vail, CO 81658 Dear Mr. Nitz: Enoneers, Surw pots & Landscape Archk cis At your request a site evaluation to determine soil suitability for an on -site sewage treatment system was performed at Lot 12, Block 1, Farview in the City of Orono, Minnesota. Standard methods of percolation testing were employed. Elevations are relative to an assumed elevation of 104.0 based at a double spike in a birch tree near the southwest property corner as set by Strgar-Roscoe-Fausch Inc. (see enclosed sketch). This report includes: 1. Soil boring logs 2. Percolation test results 3. Testhole location and septic system configuration sketch 4. Septic system design specifications 5. Discussion and recommendations. The soil boring logs show that sandy loam to sandy clay loam surface soils overlie sandy clay loam to clay subsur-face soil horizons. Soil mottling begins at 2.0 ti 2.5 feet depth at the b,�reholes. Soil mottl,2s (spots of contrasting color) are accepted indicators of periodic saturation in soils. Gleying begins at 2.0 to 5.0 feet depth at the bcreholes. Gleying (dull gray soil color) forms in soils which are saturated and Ln a chemically reduced condition for long periods of time. Ground water was at elevation 94.1 to 94.8 at the boreholts or Tanuary 9, 1987. Percolation test results are as follows: Hole Elevation Depth (inches) Soil Texture at Bottom cf Hole Percolation Rate min ink_ P-1 98.4 24 Sandy loam 3 P-2 98.1 24 Sandy loam to sandy 9 clay loam P-3 96.6 18 Sandy clay loam 5 P-4 95.8 18 Sandy clay loam 8 P-5 98.6 24 Sandy cl--y loam 5 P-6 96.8 24 Sandy clay loam 6 222 Monroe Street Eugene 1. Hakanson. PL Anoka. Minnesota 55303 James M. Wlnter. L.S. Lawrence G. Koshak, PL 612/427-5860 Peter R Raadkka. PE.. Mr. David Nitz Pag s 2 January 12, 1987 Measured percolation rates are consistent to somewhat rapid for the texture of the soil materials in which the percolation tests were run. The City of Orono requires at least three feet elevation difference between the bottom of the filter rock of a septic system and ground water or indication of periodic soil saturation such as soil mottling. To meet this requirement, a mound septic system is recommended for the primary and secondary septic systems at this site. The mound is designed to serve a four bedroom house with a whirlpool bath. Design sewage flow for the house is 600 gallons per day. A sewage flow of 100 gallons per day is added for the whirlpool bath. Total design sewage flow is 700 gallons per day. with a design infiltration rate of 1.2 gallons effluent per square foot per day for the medium sand fill material of the mound, the required rock bed area of the mound is 700 square feet. 700 gal/day 1.2 gal/ft2/day = 583 ft2 A rock bed 10.0 feet wide by 60.0 feet long provides the needed area. A minimum of one foot (1.01) of medium sand should be constructed below the rock bed. The pressure distribution system of the mound consists of Schec _e 40 PVC plastic pipe. The supply pipe should slope back towards the pumping chamber so that it drains after the mound is dosed. The la::ezals are 1.5 inch inside diamete- r-pes. The laterals should have 1/4 inch diameter holes drilled at a spacing of 3.0 feet. The laterals should be assembled to the manifold so that the holes point downwards into the rock bed. The distal ends of the laterals should be drilled norizontally in the end cap near the crown of the pipe to facilitate air venting. A submersible effluent pump capable c•f deliver.Lng at least 45 gallons per minute against a total dynamic head of at least 10.2 feet should be selected. Headlosse- are calculated as follows: 1. Verti.:al headloss of 4.5 feet between pump disc,arge (approx. elev. 95.0) and manifold (approx. elev. 99.5), i�tion �oss of 0.7 feet in 20 feet of supply pipe (3.3 feet per 100 feet 2.0 inch I.D. plastic pipe at 45 gpm flow), 3. Five feet (5.01) to account for losses in distribution network. M. David Nitz Page 3 January 12, 1987 If as -built elevations are different from those above, headloss should be recalculated to ensure proper pump selection. The pump should be rigged with mercury float switches to dose about 175 gallons of effluent to the mound. An additional mercury float switch should be installed on a separate circuit to an alarm device to warn of failure. The mercury switches should be rigged to allow 700 gallons reserve capacity in the pumping chamber. All electrical connections should be watertight. The septic tanks should each have at least 1,000 gallons capacity. The pumping chamber should have at least 1,000 gallons capacity. It is recommended that a water meter be installed to monitor water use. Exterior sillcocks should be excluded from the metered water system. The water meter should be read periodically and water use patterns adjusted if necessary to ensure that the design sewage flow of the septic system is not exceeded. The area for the proposed primary septic system should be roped off to prevent vehicular traffic on the site. Construction of the mound system should begin only when the moisture content of the topsoil is lower than the plastic limit. It is highly recommended that the installer of this septic system holds an Individual Sewage Treatment Systems Certificate for installation issued by the Minnesota Pollution Control Agency. The sole purpose of soils data contained herein is evaluation of soil suitability for on-ait,�t absorption of septic tank effluent at the test site. AlthOlAgh so'_1 texture and horizonation information and groundwater elevation data may be helpful for the setting of basement elevations at this site, we cannot warrant any such inter- pretations or use of this c.ata for other purposes. If you have any questions about information contained in this report, please feel free to contact me. Sincerely, HAKANSON ANDERSON ASSOCIATES, INC. . Aa, " If. ( /" <- - - - - - " Gary J. thbun, Soil Scientist Enclosures File: 1540.07 PMWT: Nitz Site Evaluation FILE No. 1540.01 BMING ItM: 4" Flight Auger WE: 1/9/87 (feet) 0.0 ark brown sandyloam---- Dark grayish brown sandy loam o sandy clay loam ,rayish brown sandy clay, few o many yellowish brown ttles with depth, few to ny gray gleyed areas /depth I END OF BORING 1.1 2A 7.( Borehole i 1 FI NaTtnu - aA *Ground water at 94.8 on 1/9/87 WAM NCUSM ASSOCIATES, INC. AP 3.0 5.0 7.5 Borehole / 2 rk brown to ac c san y lay loam, moist to wet ith depth Dark grayish brown sandy clay loam Gray clay, many yellowish brown mottles Grayish brown sandy clay, many red mottles, many gray gleyed areas END OF BORING *Ground water at 94.4 on 1/9/87 BY: ,� 1 PfVjECT; Ni tz Site Evaluation RLE No. 1540.01 BORIM MEhw: 4" Flight Auger DOE: 1/9/87 DfeDEPTH 0. 0 1.0 1.5 2.5 4.0 991 Borehole / 3 FI LVATf nu - 07 C ark brown sandy loam to sand lay loam Grayish brown sandy loam to sandy clay loam Brown sandy clay loam Grayish brown sandy clay. many yellowish brown mottles, many gray gleyed area,, wet Grayish brown sandy silt, many yellowish brown mottles, many gray gleyed areas, wet Grayish brown sandy clay, many yellowish brown mottles, many gray gleyed areas END OF BORING roundat 94.1 on O`1 >I T�• �•� .r "ee Borehole i .