HomeMy WebLinkAbout1988-04-28 Septic System Design ReportSystem Design
for Thomas R. Smieja
on Lots 1 and 2, Block 2, Swan Lake Addition
Orono, Minnesota
4-28-88
This lot was originally tested in June of 1980 and because of evidence of
a high water table the highest part of the lot in the southwest corner was teLt-
ed. With mottled soil found at the 4 foot level then in soil boring # 2, the
site was just at the limit for a shallow trench vs. a mound system. On 4-28-88
a new soil boring was taken near soil boring No. 2 with mottled soil found in
much the same manner at 3.8 feet. Another soil boring was taken downhill to the
north where mottled soil was found at 3.0 feet with a nice 1.5 foot layer of
black loam at the surface.
Thus, because the origi,i6_1y site would involve cutting down the trees,
installing an interceptor drain as originally recommended. be right at the
margin for trenches, and be almost as costly as a me;lnd system, it is recommend-
ed that a mound be installed in the open area to the north of the woods allowing
the wooded area to be used as an alternate site.
Design information follows for the system. In addition, two septic tanks of
at least 1000 and 750 gallons are needed along with a third pumping tank of at
least 750 gallons. An alarm device should be used to warn of pump failure. All
construction and materials must adhere to the provisions of the City of Orono.
All grading and construction traffic must he kept off both the primary and al-
ternative drainlield areas.
If any additional information is needed, please contact me.
Sincerely,
PERCOR, INC.
Mark S. Gronberg
rA woo-.� 'o
OL/ M
-Z
To/,1 J M/ errA
'h' dFORz. o/H S r-15
PUMP SELECTION PROCEDURE
A. Determine pump capacity:
1. Minimum suggested is 600 gallons per hour (10 ppm) -
to stay ahead of water use rate
2. Maximum suggested for deliver- to a drop box of a home
system is.2700 gallons per hou; (45 gpm) to prevent
buildup of pressure in drop box
3. Use value from design of pressure distribution system
SELECTED PUMP CAPACITY . . . . . . . . . . . . . . . . _
�S S gpm
B. Determine head requirements:
1. Elevation difference between pump and point of discharge
5 f feet
2. If pumping to a pressure distribution system, add 5 feet
for pressure requited at manifold . . . . . . . . . .
.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. = 7. /'j ft/100 ft
b. Determine total pipe length from pump to discharge
point. Add 25 percent to pipe lei .:tlh for fitting
loss, or use a fitting loss chart. Equivalent pipe
lengt'o - 1.25 times pipe length = 1.25 x / 50
S feet
_f�1;
c. Calculate total friction loss by multiplying;
friction loss in ft/100 ft by equivalent pine
length.
'total friction loss = 7. /y Y. /.F73' •-
Y feet
_�_�_
4. Total head required is the sum of elevation difference,
special head requirements, and total friction loss.
S + + 5 +
TOTAL HFAD . . . . . . . . . . . . . . . . . . . . . .
z �. Y t f ec t
C. Pump selection
I. A pump must be selected'Eo deliver at least ? S. S gpm
with at least 27.11 ! feet of total head.
D. To maximize pump life select sump size for 4 to 5 r,^rp
t:perations per day.
Calculate drainback
1. Determine total pipe l.eng'.h, feet.
2. Determine liquid volume r:j pipe, gallons per
100 feet. (See page E-18)
3. Mnitip,'.y length by volv.iie: Drainbac. antity =
feet x gallons/100 ft = gallons
A. Suggested drainback _ --tity is 10 percent of pumped quantity.
A larger drainback pe ;rare will decrease r.—P station
efficiency -slightly but pumping energy costs a.e usually a
relatively small part of the tucal householc: ;r^.y costs.
Ta'W r'r / Fr.o
y d'ev" n f
BOUND DESIGN PROCEDURE
(For Flows up to 1200 gpd)
A. Sewage Flow Rate
See D-7 or I-3, 4, or 5, or use
metered value; Flow Rate =
IC0 6p gpd
B. Septic Tank Liquid Volume
(see C-3 or C-5) /pOO gallons
C. Soil Characteristics
1. Depth to restricting layer
such as seasonally saturated
soil, bedrock, coarse soil,
etc.; -7C inches
2. Depth of percolation tests;
__inches
3. Number of percolation test
holes; 6 holes
4. Ave. percolation rate;
/7. mpi
5. Landsiope -
D. Rock Layer Dimensions-
1. Multiply gpd by 0.83 to
obtain required area of
rock layer;
1(00 gpd x 0.83 - JeV sq f c
Select width of rock layer
(10 fiat or lest-'• _ /-feet
3. ength of rock .Byer - Area
- Width Sou sq f t = /o f t
= So ft
Rock Volume
1. Multiply rock area by rock del:th
t )ic feet of rock;
x 0.7y f t= ?75cu f t
2. Divide cu ft by 27 cu ft/c., yd
co get cubic yards; /3,S
3. Multiply cubic yards by 1.4 to
pr weight of rock in tons;
i},3 yds x 1.4 a 1R4/tons
E-19
F. Pressure Distribution System
1. Select nu-iLer of perforated
laterals 6
2. Select perforation spacing
3 ft
3. Select perforated lateral
length; Note if mania*old is
at end of rock layer, lz..eral
length is rock layer length
les! f a ,perforation
spac :f ::u.nifold is in
Cc- to)of rock layer, lateral
length is one-half rock layer
length less half a perforation
spaying. Perforated latera).
length = Z , 5 ft.
4. Divide lateral length '.;;• pc::for-
a tion spacing to r numbr r of
perforations per lateral
73.5 feet ' 7 feet = 8 perfs
Note: la::, , _rforatior must be
in end cap, (see page E-14)
5. Mul perforations per
lai(: y number of 1-terals
to Fed total number ui
perforations;
F_perfs/lat x 6 lats
6. Determine ruquircd flow gate
by multiplying number
perforations 1,v _low
perforation (see -)age 7)
_,perf s x ,7gpm/pert
7. Select minimum required lateral
diameter from tabl, or. Pate is-17;
-cr Lable v- ti. peroration
spacing, perft: . -_ion diameter,
and number of perforations per
lateral. S''.ct minimum
diameter for perforated lateral
inches 'f rc / % ••
Basal Width
— Percolation rate in tor, 12
inches of soil is f 1. /mt,i
2 :.elect allowable soil leading
tote from table o- page E-16;
gpd _ 2
E-20
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 = 0.60gpd/f t2 = I. 0
Check this value on page E-16.
4. Multiply basal width ratio by
rock layer width to get
required basal width;
Z.0 x _of t= 20 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
20 ft- /O ft = _oft
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;
/0 x % 100 =0.`i ft
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.y ft + / ft a /.y ft
d. Add depth of clean sand at down -
slope edge to depth of rock
layer to depth of soil backfill
to get mound height at downslope
edge of rock layer;
/.Vft +Q,75ft +/.Zsft - -?.yft
e. Enter table on page E-18 with
landslope and downslope dike
ratio. Select dike multiplier
of .?. S/ / 3: / lYOo"f
H.2.f. Multiply dike multiplier by
downslope mound height to get
downslope dike width;
-7.VI x .7.1/ = 1/ 6'ft
g. Compare the values of step 11.1
and step 11.2.f. Select the
greater of the two values as
the downslope dike width;
//. 6 feet
h. Calculate upslope dike width
using upslope mound height
and upslope dike multiplier
trom pages E-18; y 0 f t
i. Total mound width is the sum
of upslope dike width plus rock
layer width plus downslope dike
width;
80ft + /0 ft +//6ft =?9.Cft
3. If landslope is 2.9 percent or
less, basal width includes both
the upslope and do:nslope dike
widths.
a. Calculate downslope dike: width
using steps N.2.a. through
11.2.f; feet
b. Calculate upslope dike width
using upslope mound height and
dike multiplier from Pale 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
G.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 downslopo
dike width.
LOTS 1&2, BLOCK 2
SWAN LAKE ADDITION
ORONO, MINNESOTA
Percolation Results
Hole No.
Material
Percolation Rate
P-1
Brown Loam
li}. 1 Min. /inch
P-2
Brown Loam
16.0
P-3
Brown Loam
20.9
P-4
Brown Loam
17.1
P-5
Black Loam
20.0
P-6
Black Loam
14.1
The average percolation rate is 17.0 minutes per inch.
Soil Borings
S.B.# 1
Depth(ft.)
Material
0.0-1.2
Black
Loam
1.2-2.2
Dark
Brown Clay Loam
2.2-2.8
Brown
Clay Loam
2.8-4.8
Brown
Loam
4.8-8.0
Brown
Clay Loam
Mottled soil at 5.0 feet and water
table at 5.4 feet after 24 hours.
S.B.# 3
Depth(ft.) Material
0.0-2.0 Black Loam
2.0-2.8 Brown Loam
2.8-6.0 Brown Clay Loam
Mottled soil at 4.5 feet and water
table at 4.9 feet after 24 hours.
S.B.q 2
Depth(ft.) Material
0.0-2.0 Black Loam
2.0-3.0 Brown Clay Loam
3.0-6.0 Brown Loam
Mottled soil at 4.0 feet and water
table at 4.3 feet after 24 hours.
E
Logs of Soil Borings
B- 31
Location or Project 7yo,W.1 /' J'M/fj;.r
Borings made by C�'a.�/� 0"4: Date -1/-I d''Ji'
Classification System: AASHO — _; USDA-SCS X ; Unified other _
Auger used (check two): Hand ZC or Power _; Flight _, or Bucket X other
Depth, Boring number — Depth, Boring number
in
feet I Surface elevation feet in Surface elevation
OL.I Pw (a,11"
1—
epdn
2 —
Aet-U r✓ CL.► r l O/1lYl
3—
4
5 —
6 —
7 —
8 —
End of boring at `/ S feet.
Standing water table:
Present at feet of depth,
hours after boring.
Not present in boring hole ><
Mottled soil:
Observed at 7. F feet of depth.
Not present in boring hole
Observations and comments:
W�
2 --
3 —
4 —
5 —
6 —
7 —
8 —
BGAPP !GA/Yl
,.f'44'-- C.
End of boring at _?_ s feet.
Standing water table:
Present at feet of depth,
hours after boring.
`lot present in boring hole X
Mottled soil:
Observed at feet of depth.
Not present in boring hole
Observations and comments:
cz-
Additional System Design Information
for Thomas R. Smieja
on Lots 1 and 2, Block 2, Swan Lake Addition
Orono, Minnesota
20 c,yG � JC_ _7 F"Clff
5-9-88
Because of the need to move the driveway farther to the south, a new area
was tested for a mound system just to the north of soil boring No. 5. Addition-
al information follows for these results. The design of the system is basic-
ally the same except for the change in location of the tanks, driveway and
mound site.
If any other information is needed, please contact me.
Sincerely,
PERCOR, INC.
Mark S. Gronterg
w
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y BEORooiKS r•-15
PUMP SELECTION PROCEDURE
A. Determine pump capacity:
1. Minimum suggested is 600 gallons per hour (10 Rpm) -
to stay ahead of water use rate
2. Maximum suggested for delivery to a drop box of a home
system is.2700 gallons per hour (45 Rpm) to prevent
buildup of pressure in drop box
3. Use value from design of pressure distribution system
SELECTED PUMP CAPACITY . . . . . . . . . . . . . . . . ,�s .S 9PM
B. Determine head requirements:
1.
Elevation difference between pump and point of discharge
_ _,5_ feet
2.
If pumping to a pressure distribution system, add 5 feet
S
for pressure required at manifold . . . . . . . . . .
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. - ? 1Y f t/100 ft
b. Determine 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 150
feet
c. Calculate total friction loss by multiplying
friction loss in ft/100 ft by equivalent pipe
length.
'total friction loss 7. /y x /. F71 =
_/_�, `/ _ feet
4.
Total head required is the sum of elevation difference,
special head requirements, and total friction loss.
.S + + s + _/.?. Y
Z 3J Y t feet
TOTAL HEAD . . . . . . . . . . . . . . . . . . . . . .
_
C. Pump selection
1. A pump must be selected to deliver at '_east .75. 5 gpm
with at least 2 3.4V $' feet of total head.
D. To maximize pump life select sump size for 4 to 5 pump
operations per day.
i'. Calculate drainback
1. Determine total pipe length. feel.
2. Determine liquid volume of pipe, g::llons per
100 feet. (See page E-18)
3. Multiply length by volume: Drainback quantity =
feet x gallons/100 ft - gallons
4. Suggested drainback quantity is 10 percent of . ,ed quantity.
A larger drainback percentage will decrease g•. -.•tion
efficiency -slightly but pumping energy costs a I•ly a
relatively small part of the total household c•
tests.
�% d fORG o�h S
PUM1' SELECTION PROCEDURE
A. Determine pump capacity:
1. Minimum suggested is 600 gallons per hour (10 gpm) to stay ahead of water use rate
2. Maximum suggested for delivery to a drop box of a home
system is.2700 gallons per hour (45 gpm) to prevent
buildup of pressure in drop box
3. Use value from design of pressure distribution system
F-15
SELECTED PUMP CAPACITY . . . . . . . . . . . . . . . . S
B. Determine head requirements:
I. Elevation difference between pump and point of discharge
'f_ feet
2. If pumping to a pressure distribution system, add 5 feet
_,5
for pressure required at manifold . . . . . . . . .
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. = 7 /Y ft/100 It
b. Determine 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 150
7,S feet
c. Calculate total friction loss by multiplying,
Friction loss in ft/100 ft by equivalent pine
length.
Total friction loss = _7, /y r. /. P7.S
�/ feet
_ __
4. Total head required is the sum of elevation difference,
_/�, _
special head requirements, and total friction loss.
S f + s + /�. Y
TO'rAL IIRAD . . . .
7 f/ +
. . . . . . . . . . . . . . . . .
feet
C. Pump selection
1. A pump must be selected to deliver at '_east -7S. 5 gpm
with at least 2 Y.V ! feet of total head.
D. To maximize pump life select sump size for 4 to 5 pump
operations per day.
E. Calculate drainback
I. Determine total pipe length, _ feL-t.
2. Determine liquid volume of pipe, p,.:llons per
100 feet. (See page E-18)
3. Multiply length by volume: Drainback quantity =
feet x gallons/100 It = gallons
4. Suggested drainback quantity is 10 percent of r -led quantity.
A larger drainback percentage will decrease I •:tion
efficiency - slightly but pumping energy costs :. '.ly a
relatively small part of the total household t. sts.
Tom
'Y
MOUND DESIGN PROCEDURE
(For Flows up to 1200 gpd)
A. Sewage Flow Rate
See D-7 or I-3, 4, or 5, or use
metered value; Flow Rate =
grD O gpd
B. Septic Tank Liquid Volume
(see C-3 or C-5) /g gallons
C. Soil Characteristics
1. Depth to restricting layer
such as seasonally saturated
soil, bedrock, coarse soil,
etc.; -76 inches
2. Depth of percolation tests;
_ /flinches
3. Number of percolation test
holes; 2 holes
4. Ave. percolation rate;
S. a mp i
5. Landslope - Z/ _%
D. Rock Layer Dimensions'
1. Multiply gpd by 0.83 to
obtain required area of
rock layer;
COO gpd x 0. 83 - J?V sq f t
2. Select width of rock layer .
(10 feet or less) = L-feet
3. Length of rock layer - Area
Width Soo sq f t L /o f t
So f t
E. Rock Volume
1. Multiply ruck area by rock depth
to get cubic feet of rock;
Soo sq f t x 0.75 f t= _77.Scu f t
2. Divide cu ft by 27 cu ft/cu yd
to get cubic yards; /_?,9
3. Multiply cubic yards by 1.4 to
get weight of rock in tons;
/1.9 cu yds x 1.4 - /9 Ytons
E-19
F. Pressure Distribution 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 - Z , S f t.
4. Divide lateral length by perfor-
ation spacing to get number of
perforations per lateral
23.5 feet _ _?feet - 8 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;
-ff_perfs/]at x 6 lats = yJP
6. Determine required flow rate
by multiplying number of „.A
perforations by flow per V`1 rxFS,
perforation (see page E-17)
_ —perfs x,7Zigpm/perf=j?S.Sgpm
7. Select minimum required lateral
diameter from table on Page E-17;
enter table witli perforation
spacing, perforation diameter,
and number of perforations per
lateral. Select minimum
diameter for perforated lateral
= / Yy inches a rf / 91' "
G. Basal Width
1. Percolation rate in top 12
inches of soil is 'mpi
2. Select allowable soil loading
rate from table on page E-16;
��'. 0, 60 gpd/ft2
1:-20
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/ft2 ; 0.9dgpd/ft2
Check this value on page E-16.
4. Multiply basal width ratio by
rock layer width to get
required basal width;
Z.0 x LO ft = 20 ft
H. Downslope Dike Width
11.2.f. Multiply dike multiplier by
downslope mound height to get
downslope dike width;
3.ti/ x -7.`/ _ //.6ft
g. Compare the values of stela :{ l
and step 11. 2. f . Select the
greater of the two values as
the downslope dike width;
//. 6 f e e t
1. If landslope is 3% or more, i
subtract rock layer width
from basal width to obtain
minimum downslope dike toe width
20 ft - /O ft = eft
Calculate upslcpe dike width
using; upslope mound height
and upslope dike multiplier
f_rot� page E_-18; 0 ft
'total mound width is the sure
of upslope dike width plus rock
layer width plus downslope dike
width;
BQft + /0 ft +//6ft=?9.6ft
2. Calculate mound height at edge
3. If
landslope is 2.9 percent or
of
rock layer on downslope side;
less,
basal width includes both
a.
Determine depth of clean sand
the
upslope and do•..nslope dike
fill at upslope edge of rock
widths.
b.
layer: _ / feet
`?ultiply rock layer width by
a.
Calculate downslope dike width
landslope to determine drop
using stets H.2.a. hruus;h
in elevation;
H.2.f; feet
/D x Y `/, = 100 =O.`i f t
b.
Calculate upslope dike width
c.
Add drop in elevation Co depth
using upslope mound height and
dike multiplier frog. Page E-18;
of clean sand at upslope edge
ft - ft
of rock layer to get depth of
clean sand at downslope edge
c.
Add downslope dike width to
of rock layer.
upslope dike width to rock
d, Y f t + / f t = /. Y ft
layer width to get total mound
d.
Add depth of clean sand at down-
width;
slope edge to depth of rock
—ft + ,ft + _ft = _ft
layer to depth of soil backfill
d.
Compare total mound width to
to get mound height at do -%%slope
required basal width from step
edge of rock layer;
G.4. If total mound width is
/, / f t +49,7Sf t + /, 2S'f t = 3. Y f t
grr_a ter than required basal
e.
Enter table on page E-18 with
width, use calculated dike
landslope and downslope dike
widths. If required basal
ratio. Select dike multiplier
width is greater than total
of
mound width, increase downslope
dike width.
j Logs of Soil Borings
tcrl / 2 C�cGrx ----- B-31
Location or Project ''�,.- �Arr �,�� . r•�• -
Borings made - by &r, :c :. r7 — Date_ -
Classification System: P.ASHO USDA-SCS X ; Unified other ^
Auger used (check two): Hand �, or Power _; Flight _, or Bucket x other
Depth, Boring number G Depth, Boring nun.ber iin
in
feet Surface elevation feet Surface elevation _
n n
1 —
2 —
3 —
4 —
S —
6 —
7 —
8 --
End of boring at q.. G feet.
Standing water table:
Rresent at feet of depth,
hours after boring.
Not present in boring hole x
Mottled soil:
Observed at _7, G feet of depth.
Not present in boring hole
Observations and co=ents:
1 —
2 —
3 —
1 4 —
1 S —
7 ---
3 —
?nd of boring; at �� � feet.
standing water table:
'resent at feet of depth,
hours after boring.
sot present in borin,p, hole
;ottled soil:
)bserved at f. D feet of depth.
Not present in boring hole
Observations and coi=ents:
PERCOLATION TEST DATA SHEET L-39
CATS
Test hole location
C.TA Hole number %
Date test hole was prepared_ 5- S+15U Depth of hole bottori, /8 inches.
Diameter of hole, _60— inches.
Soil data from test hole:
Depth, inches
Soil texture
------------
Method of scratch'.ng sidewall 4le. 5C/cj
Depth of pea -sized 8ravel in botto:c of hole, inches.
Date and hour of initial water filling y Q
Depth of initial water filling, / -
- inches above hole bottom.
Method used to maintain at least 12 inches of water depth in hole for at least
4 hours A1 16 C
Percolation test readings made by /71
on
starting at / / ;
2•f3ximum water d^_pth above hole botto:::
duri- :est, 1 4— inches.
Time
Time
Interval,
Measurement,
Drop in water
Percolation
Minutes
inches
level, inches
rate,
minutes per
Remarks
inch
/r6 ��q b
1 z B
D
�r
--
3
/ o �T—
S /—�-�
58
5.3
Percolation rate = 5.3 minutes per inch.
PERCOLATION TEST DATA SHEET
Test hole location_ Aft ,ri4- Bole number 8
Date test hole wis prepared 5-5--SS Depth of hole bottom, A8 inches.
Diameter of hole_ iO inches.
Soil data from test hole:
Depth, inches Soil te:•;ture
Method of scratching sidewall — AeWr sc- -fc k 'e
Depth of pea -sized gravel in bottom of hole,
�1 _ _ inches.
Date and hour of initial water filling 4• % 30 5-- 5.8s
Depth of initial water filling, /
5 inches above hole bottom.
Method used to maintain t least 12 inches of water depth in hole for at least
4 hours r 'e I c % V ii LL
Percolation test readings evade by
starting at
(date)
during test, inches.
low
Naxirmum water depth above hole bottom
Time
Time
Interval,
Minutes
Measurement,
inches
Drop in water
level, inches
Percolation
rate,
minutes per
inch
Remarks
77,
30
-_I
Percolation rate - 1!(. 3 minutes per inch.