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Home My WebLink About1987-05-05 Septic System Design ReportJ AV,40 r;� �*r 7 Hakanson Anderson Assoc., Inc. May 5, 1987 Mr. Jim Johnson 8327 W. Bush Lake Road Bloomington, FIN 55438 Dear Jim: Jame_;! :. yoknson Aelen L. Jofwon 8.127 11Pat Bus/t Lake Road �Bloontingtott, ;11�( 554.38 Engineers, Surveyors & Landscape Architects At your request, a site evaluation to determine soil suitability for on -site sewage treatment was performed at Lot 4, Block 1, Bill Kelley's Land in the City of Orono, Minnesota. Standard methods of percolation testing were employed. Elevations are relative to an assumed elevation of 100.0 based at the top of a single spike in a six inch diameter elm tree east of the test site (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 sur- face soils overlie sandy clay loam to sandy clay subsurface soil horizons. Soil mottling begins at 1.5 to 2.5 Z."at depth at the boreholes. Soil mottles (spots of contrasting color) are accepted indicators of periodic saturation in soils. Soil gleying begins at 2.0 to 3.0 feet depth at the boreholes. Gleying (dull gray soil color) fortes in soils which are saturated and in a chemically reduced condition for long periods of time. Ground water was encountered at elevation 91.8 at borehole #4 on April 24, 1987. Percolation test results are as follows: Soil Texture at Hole Elevation Depth (inches) Bottom of Hole P-1 99.5 16 Sandy loam P-2 99.9 12 Sandy loam Percolation Rate (min/in) 1 6 222 Monroe Street Anoka, Minnesota 553C 612/427-SW Eugene J. Hakanson, CE James M. Winter. LS. Lawrence 4 Koshak. PL Peter R. Raatikka, P.E Mr. Jim Johnson May 5, 1987 Page Two P-3 100.9 30 Sandy clay loam 6 P-4 100.9 24 Sandy clay loam 7 P-5 98.0 24 Sandy clay loam 2 P-6 99.7 24 Sandy clay loam 11 Measured percolation rates are rapid for the soil textures 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 mott- ling. To meet this requirement, a mound septic system is recom- mended at this site. The mound is designed to serve a three bedroom house. Design sewage flow is 450 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 375 square feet. 450 gal/day = 1.2 gal/ft2/day = 375 ft2 A rock bed 10.0 feet wide by 40.0 feet long provides the needed area. A minimum of one foot (1.0l) of medium sand should be constructed below the rock bed. The pressure distribution system of the mound consists of Schedule 40 PVC plastic pipe. The supply pipe should slope back towards the pumping chamber so that it drains after the mound is dosed. The laterals are 1.5 inch inside diameter pipes. 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 horizontally in the end cap near the crown of the pipe to facilitate air venting. A submersible effluent pump capable of delivering at least 30 gallons per minute against a total dynamic head of at least 12.3 feet should be selected. Headlosses are calculated as follows: 1. Vertical headloss of 6.7 feet between pump discharge (approx. elev. 95.0) and manifold (approx. elev. 101.7) 2. Friction loss of 0.5 feet in 30 feet of supply pipe (1.6 feet per 100 feet 2.0 inch inch I.D. plastic pipe at 30 gpm flow), 3. Friction loss of 0.1 feet in pipe fittings equal to 25 percent of friction loss in supply pipe, Mr. Jim Johnson May 5, 1987 Page Three 4. Five feet (5.01) to account for losses in distribution network. 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 120 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 pump failufe. The mercury switches should be rigged to allow 450 gallons --.;.serve capacity in the pumping chamber. All electrical connect j s should be watertight. The two septic tanks should have at least 1000 gallons capacity each. The pumping chamber should have at least 1000 gallons capacity. It is recommended that a water meter be installed to monitor water use. The meter should be hooked to the water system such that exterior sillcocks are excluded. The water meter should be read periodically to ensure that the design capacity of the septic system is not exceeded. 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 -site absorption of septic tank effluent at the test site. Although soil 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 data 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. Gary J. iftfithbun, Soil sc ent st /ckl Enclosures File: 1601.01 LOGS OF SOIL BORINGS PmEc'; Johnson site Evalution FILE No. 1601.01 BmINIG ME11 : _ 4" Flight Auger . _ DM: 5 4 87 DEPTH 0.0 1.0 1.5 2.0 5.0 7.0 Borehole #1 Pi m rfm .. 49.5 Dark brown sandy loam to sandy clay loam Dark grayish brown sandy c a loam, moist Grayish brown sandy clay, few yellowish brown mottles, Grayish brown sandy clay, many yellowish brown mottles, many gray gleyed areas, mols' Gray sandy clay, many yellowish brown mottles, many gray gleyed areas, wet END OF BORING Ground Watar not anrniintAraA DEPTH (feet) 0.0 0.5 1.0 1.5 1oi st 2.5 7.0 Borehole #2 Fr cvarrrw — 99. 9 Dark brown sandy loam Grayish rown sandy loam to fine sand Grayish brown sandy clay loam Brown sandy clay loam Grayish brown sandy clay, many yellowish brown mottles many gray gleyed areas END OF BORING Ground water not encountered BY: LOGS OF SOIL WURINGS PROEcr; Johnson Site Evaluation FILE No. 1601.01 BORING METHOD: 4" Flight Auger DATE; 5/4/67 3.0 7.0 Borehole #3 M cveTtrw - 100.9 Dark brown sandy loam to sandy clay loam Dark grayish brown sandy clay loam Brown sandy clay loam, moist Grayish brown sandy clay loam, few yellowish brown ...ottles, moist Gray sandy clay, many yellowish brown mottles, many gray gleyed areas END OF BORING bround water not encounterea FWJ AU1iSON =IATES, INC. (feet 0.0 1.0 2.0 2.5 4.0 6.0 7.0 Borehole #4 Pi cverrnu - 98.0 Dark brown sandy loam Dark grayish brown sandy clay loam Brown sandy clay loam Grayish brown -sandy clay, many yellowish brown mottles many gray gleyed areas Grayish brown clayey sand, many yeliowish brown mottles many gray gleyed areas, moist to wet with depth Grayish brown silty clay, many yellowish brown mottles many gray gleyed areas, wet END OF BORING * Ground water at elev. 91.8 on 4/24/87 BY: 'IQ It It It r au 1 jr r.Y:•.. Z� ^",....} -r•'.T l,'Lj%-lr. tYy,,hjkt=�t��"i"i fiT.?'^' .��i �tit { :i. '�' �i�.•� y�, 1 •1. ...t�-'^' .'1. _ -_. _St y"j r"`F'+:i. LAGS OF SOIL BORINGS PROJECT: Johnson Site Evaluation FILE N0, 1601.01 &AINIG i'ET1i0O: _4" Flight Auger DATE: 5/4/81 2.%, 6.0 8.0 .Borehole #5 FI t:VATTn;d -OA 7 Dark brown sandy loam Dark grayish brown sandy clay loam Brown sandy clay loam Grayish brown sandy clay loan few yellowish brown mottles Gray sandy clay, few yellowish brown mottles, few gray gleyed areas Grayish brown sandy clay to clayey sand, many yellowish brown mottles, many gray gleyed areas, wet END OF BORING Groundwater not encountered HAKA= MUM ASSOCIATES, INC. DEPTH (feet)