HomeMy WebLinkAbout1984-12-28 Septic System Design ReportL4 Vv- U 2
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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.