HomeMy WebLinkAbout1987-08-19 Septic System Design ReportFOX�--r--
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SYSTEM DESIGN
FOR DAVID OSTREIM
OF LOT 2, BLOCK 1, BEAU MARAIS
ORONO, M!NNESOTA
8-19-87
On August 10-12, 1987 an area northwest of the house was tested for a
septic system, which because of a high water table would require a mound
system under pressure. Additional design information follows.
In addition, two septic tanks of at least 1000 and 750 gallons are
needed along with a pumping tank of 500 gallons.
All construction and materials must adhere to the provisions of the City
of Orono and the On -Site Sewage Treatment manual.
PH grading and construction traffic must be kept off both the primary
and the alternate drainfield sites. If dny additional information is needed,
please contact me.
Sincerely,
PERCOR, INC.
M� Gronberg,
PCA certified
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F.-19
OW
MO= DESIG14 PROCEDURE
(For ?lows up to 1200 gpd)
A. Sewage Flow Rate
See D-7 or I-3. 4, or 5, or use
metered value; Flow Rate =
60 O gpd
B. Septic Tank Liquid Volume
(see C-3 or C-5) /000 gallons
C. Soil Characteristics
1. Depth to restricting layer
such as seasonally saturated
soil, bedrock, coarse soil,
etc,; inches
2. Depth of percolation tests;
_inches
3. Number of percolation test
holes; 7 holes
4. Ave. percolation rate;
5. Landslope = 8 S
D. Rock Layer Dimensions
1. Multiply gpd by 0.83 to
obtain required area of
rock layer;
6pgpd x 0. 83 - Soo sq f t
2. Select width of rock layer
(10 feet or less) _ /p feet
3. Length of rozk layer - Area
Width.S:i0 sq ft - /p ft
So ft
E. Rock Volume
1. Aultiply rock area by rock depth
to get cubic feet of rock;
SDO sq f t x O.75f t =_ _775 cu f t
2. Divide cu ft by 27 cu f t/cu yd
to get cubic yards;
3. Multiply cubic yards by 1.4 to
get weight of rock in tons;
%2, cu yds x 1.4 a / , Stuns
F. Pressure Distributir-1 System
1. Select number of perforated
laterals 6
2. Select perforation spacing
3 ft
3. Select perforated lateral
length; Note if manifold is
at end of rock layer, lateral
length is rock layer length
less half a perforation
spacing. If manifold is in
center of rock layer, lateral
length is one-half rock layer
length less half a perforation
spacing. Perforated lateral
length = 9Y S f t.
4. Divide lateral length by perfor-
ation spacing to get number of
Perforations per lateral
Zf.S feet 3 feet = 9, perfs
Note: last perforation must be
in end cap, (see page E-14)
5. Multiply perforations per
lateral by number of laterals
to get total number of
perforations;
_9 perfs/lat x 6_lats
6. Determine required flow rate
by multiplying number of
perforations by flow per 'A
perforation (see page E-17) �
Y.V perfs x,7yFpm/perf=.?55'jppj
7. Select minimum required latl•1-al
diameter from table on Page f:-17;
enter table with Perforation
spacing, perforation diameter,
and number of perfurations per
lateral. Select minimum
diameter for perforated lateral
_ / /y „ inches tole I yz "
G. Basal Width
1. Percolation rate in top 12
inches of soil is X. 0IPi
2. Select allowable soil loading
rate from table on page E-16;
�� O. 7? gpd/f t2
MOUND DESIGN PROCEDURE (Continued)
(For Flows up to 1200 gpd)
G.3. Calculate basal width ratio
by dividing rock layer
loading rate of 1.20 gpd/ft2
by allowable soil loading
rate;
1.20 gpd/f t2 �-. 7 gpd/f t2
Check this value on page E-16.
4. Multiply basal width ratio by
rock layer width to get
required basal width;
,� x/ o f t^ Ls. ? f t
H. Downslope Dike Width
1. If landslope is 3% or more,
subtract rock layer width
from basal width to obtain
minimum downslope dike toe width
/�L2 ft - eft - S,2ft
2. Calculate mound height at edge
of rock layer on downslope side;
a. Determine depth of clean sand
fill at upslope, edge of rock
layer: / feet
b. Multiply rock layer width by
landslope to determine drop
in elevation;
/0x If.5 % 100 -Offt
c. Add drop in elevation to depth
of clean sand at upslope edge
of rock layer to get depth of
clean sand at downslope edge
of rock layer.
O.YISft + / ft - /.95ft
d. Add depth o-clean sand at down -
slope edge to depth of rock
layer to depth of soil backf ill
to get mound height at downslope
edge of rock layer;
JP3T t +V. 7
If t + /,15 f t 3. JSf t
e. Enter table on page E-18 with
landslope and downslope dike
ratio. Select dike multiplier
of j-, O 6 y. i fig/f
E-20
11.2.f. Multiply dike multiplier by
downslope mound height to get
downslope dike width;
d'06 x -?.YS - 2_ .aft
g. Compare the values of step 11.1
and step P.2.f. Select the
greater of the two values as
the do•+m slope dike width;
23. 2 feet
h. Calculate upslope dike width
using upslope mound height
and upslope dike multiplier
r page E-18;
;�, 9.oft
i. Total mound width is the sum
of upslope dike width plus rock
layer width plus downslope dike
%Yid th ;
j,Qf t 4- /0 f t +Zy3f t 7 3 f t
3. If landslope is 2.9 percent or
less, basal width includes bath
the upslope and downslope dike
widths.
a. Calculate downslope dike width
using steps 11.2.a. through
11.2.f; feet
b. Calculate upslope dike width
using upslope mound height and
dike multiplier from Tage E-18;
x ft ft
c. Add downslope dike width to
upslope dike width to rock
layer width to get total mound
width;
ft + ft + ft ft
d. Compare total mound width to
required basal width from step
C.4. If total mound width is
greater than required basal
width, use calculated dike
widths. If required basal
width is greater than total
mound width, increase downslope
dike width.
F-15
PUMP SELECTION PROCEDURE
A. Determine pump capacity:
I. Minimum suggested is 600 gallons per hour (10 9pm) -
to stay ahead of water use rate
Maximum suggested for delivery to a drop box of a home
system is 2700 gallons per hour (45 qpm) to prevent
buildup of pressure in drop boy
7. Use value from design of pressure distribution system
SELECTED PUMP CAPACr'ry . . . . . . . . . . . . . . . . 35, 5 l:pm
R. Determine head requirements:
I. Elevation difference between pump and point of discharge
$_ feet
2. If pumping to a pressure distribution system, add 5 feet
T
for pressure required at m.,nifold . . . . . . . . . .
S feet
3. Friction loss _
a Enter friction loss table with gpm and pipe diameter.
Read friction loss in feet per 100 feet from page F-18.
F. L. - 6 9gr ft/100 ft
b. Petermine total pipe length from pump to discharge
point. Add 25 percent to pipe length for fitting
loss, or use a fitting loss chart. Equivalent pipe
length - 1.25 times pipe length - 1.25 x ,_Q
feet
_
c. Calculate total friction loss by multiplying
friction loss in ft/100 ft by equivalent pine
length.
'total friction loss 9C'11ee x <<_ S
feet
—�
+• Tor, -.I head required is the sum of elevation difference,
special head requirements, and total friction loss.
'? + s + _yam_
TOTAL HEAD . . . . . . . . . . . . . . . . . . . . . .
/1', ji feet
C. Pump selection
1. A pump must be selected to deliver at least 3S. S gpm
with nt least /T _�/ fret of total head.
D. To maximize puir.p life select sump size for 4 to 5 pump
operations per day.
1{. Calculate drainhack
I. Determine total pipe length, _ feet.
2. Determine liquid volume of pipe, gallons per
100 feet. (See page E-18)
3. Multiply length by volume: Drainback quantity =
feet x gallons/100 ft = gallons
4• Suggested drainhack quantity is 10 percent of pumped quantity.
A larger drainback percentage will decrease pump station
efficiency slightly but pumping energy costs are usually a
relatively small part of the total household energy costs.
m- 35
PERC01ATION TEST DATA SUM
Teat hole location_ /X,49 • ;/�� _ Uole number
Date test hole was prepared 7 Depth of hole bottom, inches.
Diareter of hole, ,; inches.
Soil data.from test bole:
Depth, inches
Soil texture
Methoc of sc:a:c}inq sidevall /✓/44*
a° pea -sited gravel in bo:to= of hole, _ inches.
:,-�
a:< <-.: :�,;_. cf :r:itial rater i_.l::,g 7.' � ii�t f i- P7
Da initial rater filling, inches above hole bottom.
Kctto-- used to raintain at least 12 inches of water depth in hole for at least
'rerc_'lation test readings made by ;.-a i- Ir Z on
7 starting at :fl Maximum water depth above hole bottom
(L:a_e)
dvr•-ng :est, inches.
;ire
'i_e
;r.te n al,
mutes
�
Measurement,
i inches
I
Dzop in eater
level, inches
Percolation
rate,
minutes per
inch
Remarks
o..
/Ire ; <!
-7
10
4.14
y"71
ainutse Osr toe".
?arcolation rats � '
8- 3S
PERCOLATION TEST DATA SHEL?
Teat hale location_ g&t-ly 41rRFinl Bole nuzber a
Date teat hole was prepared A0 7 Depth of hole bottom,15 inches.
Diameter of hole, ___C_ inches.
Soil data.from test bole:
Depth, inches
veiti'.d Of sc:&:c�:nR s:dewall _�i�. i•'.'
Soil texture
o- ;ea -fixed gravel in bottor. of hole, lashes.
:,a:r E-.- hC'-'7 cf in:.tial water filing 7:J0 /At r-1i 7iR7
:: ini:=ai water filling, 0- inches above hole botto=.
X::`od ::sed to maintain a: least 12 inches of water depth in hole for at least
Per:clarion test readings made by „ocr _ on
S'' t'7 starting at yp g II Maxim= water depth above hole bottom
(da:e)
dur'_^g :est, inches.
8 4 9 i
lire
' '`:mutes
Measurement.
I inches
I
// G
Drop in eater
level, inches
Percolation
rate,
minute. per
inch
Remarks
'7/1
6
5/ o
IJ , 15
11 3-1
30,
103i�6
I
I
Percolation rats •
2 alnutes Per ieel+.
Loes of Soil Borinas
B-27
:.ocation or Project 441ZIZl
Borings made by &SIC 6 eA-10' 'F C((kK ay'.-,.✓rWC Date ,7-iG -,P7
Classification System: AASHO USDA-SCS Unified other T
Auger used (check two): Hand or Power _; Flight or Bucket ?K_; other
Depth, Boring number, Depth, Boring number 2
in Surface elevation in Surface elevation
feet feet
r�' ■T� NC
J'lACA' t o• r^
bf,p0 e- w• [ 'PA i% I
End of boring at �_ feet.
Standing water table:
Present at feet of depth,
hours after boring.
Not present in boring hole ><_—.
Mottled soil:
Observed at 2 G feet of depth.
Not present in boring hole
Observations and comments:
&4Ck c o.4^
1 —
2 '-
3
4 —
5 —
6 ---
7 —
F�
'dxt'A"',
Cnd of boring at feet.
Standing water table:
Present at feet of depth,
hours after boring.
,lot present in boring hole _.
klottled soil:
Dbserved at L. O feet of depth.
Not present in boring hole
Observations and cosrnents:
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SYSTEM DESIGN
FOR DAVID OSTREIM
OF LOT 2, BLOCK 1, BEAU MARAIS
ORONO, MINNESOTA
3-28-87
1. Percolation Rate. Type of System.
21.6 minutes pf ch, Shallow Trench System.
2. Proposed Flow Race.
3 bedrooms @ 150 G.P.D. = 450 G.P.D.
3. Soil Treatment Area Required.
Use 2.0 factor x 450 G.P.D. = 900 SQ. Ft. minimum.
4. Size and Number of Trenches.
3 trenches 3 feet wide and 100 feet long = 900 Sq. Ft. These trenches would
be o.5 feet deep in the natural soil so loam fill would be needed over the
top, and they would be a minimum of 7.5 feet apart center to center.
5. Drainfield Rock Needed.
33.3 cubic yards of rock is needed to have 6 inches under and 2 inches over
a 4 inch distribution pipe.
6. Septic Tanks.
Two septic tanks of at least 1000 and 750 gallons are needed. In addition
a third pumping tank and pump are needed to reach the higher drainfield
area.
7. Additional Information.
All materials and construction must adhere to the provisions of the City of
Orono. Also, runoff water must be diverted from the drainfield site and both
the primary and alternate areas must be kept free from grading and construc-
tion traffic in order to preserve the natural soil.
If any additional information is needed, please contact me.
Sincerely,
PERCOR, INC.
; ,a%rK�-t;rg.
ark S
PCA certified