1984-12-28 Septic System Design Report

Home Browse Search

L4 Vv- U 2 � 2 SYSTEM DESIGN FOR GARY RODERICK LOT 3, BLOCK I, RINGERSW000 3 ORONO, MINNESOTA CIS Y 12-28-84 1. Percolation Rate, Type of System. Percolation tests were taken by others. From information supplied, the pri- mary site had a rate of 18 minutes per inch, but a possible water table at 1.5 feet. Thus, a pressure mound system according to basal width would be required. Contour lines shown on the attached drawing were from our own topography taken recently. 2. Proposed Flow Rate. 4 bedrooms @ 150 G.P.D. is 600 G.P.D. 3. Soil Treatment Area Needed. 600 G.P.D. x 0.83 factor is 500 Sq. Ft. of rock bed area or a bed 10' wide by 50' long. 4. Septic Tanks and Distribution System. Two septic tanks of 1000 gallons each are recommended. In addition, a third pumping tank will be needed to house the pump required for pressure distri- bution to the mound area. Distribution to the rock bed is to be through 3 perforated laterals 40" apart All construction and materials should adhere to the provisions of the city of Orono. 5. Mound Dimensions. o r a percolation rate of 18 MPI a factor of 2.00 would be used as the minimum. However, since it appears from the results that one hole was not used in calculating the average, a factor of 2.67 used for 46-60 MPI should be used. This would result in a total basal width of 10 x 2.67 or 26.7 feet. Since the ground slope is around 6% only the downslope can be used for this width. Thus, this downslope dimension will have to be 26.7-10 or 16.7 feet. However, with the high water table 2 feet of sand will be needed instead of I foot. Thus, the mound will be 4 feet high instead of 3 feet, and with a minimum allowable sideslo pe of 3:1 the downslope side would need to extend 16.8 feet. All other sides of the mound would slope down at a minimum of 3:1. If there are any other questions, please contact me. Sincerely, PERCOR, INC. ,+ Mark S. Gronberg, P.E.