HomeMy WebLinkAbout1991-11-11 Septic System Design ReportIVIL/UIVU ULLOMIlIV lVUltA01VILLL
(For I -lows up to 1200 gpd)
A. FLOW
Estimated --�� gl)cl (seepages D-7 or l-3, 4, 5)
or measured gpd x 1.5 =
B. SEPTIC TANK LIQUID VOLUMES
foo0 _# / - tewpA gallons (see pages C-3 or C-5)
C. SOILS (refer to site evaluation)
1. Depth to restricting layer = inches
2. Depth of percolation tests = I':t inches
3. Percolation rate '� mpi
4. Land slope Q %
1'.nimaled Sewage Fluws in Odlu�,s pv day
tcl+d>
of
Type I
Type 11
Typn ill
T�pe
Iledrooms
2
3011
225
180
9
450
3W
219
Boa
4
6011
375
256
5
750
450
294
1.
6
9011
525
332
1
7
1050
600
370
Ill
8
1200
675
AIN
ed w.w
Seek Ta.k Cap ilkra, in p/r.
Nwnhe e!
Miain vin Llpid
lAvid espacily .ith
Ikdr.s..a
C-PW"
karkqr di4 wal
2wkn
750
1IM
3w4
Ian
ISM
4wi
IS1U
tLS11
7.9.9
iJal
JIM
arm •
......
D. ROCK LAY':l% DIMENSIONS
1. Multiply ilcw rate by 0.83 to obtain required area of rock
layer: Daily Flow x 0.83 -
,07-15*6 gpd x 0.83 sq. ft./gpd = =sq. ft.
2. Select width of rock lay 1r (10 feet or less) _ . AO - ft.
3. Length of rock layer = Area + Width -
4az Sq. ft. + ,! ft. = &9 ft. Rock Bed
E. ROCK VOLUME
1. . ,w *Multiply rock area by rock depth to get cubic feet of rock;
} �esq. ft. x � f c. _ �,�,Zcu. ft..'
` Divide cu. ft. by 27 cu. ft. /cu. yd.. to get cubic yards;
ft. + 27 = cu. yd.
3..:`. `Multipl cubic yards by 1.4 to get weight of rock in tons;
'cu. yd. x 1.4 ton/cu. yd. -.U. tons.
F. ADSORPTION WIDTH
1. Percolation rate in top 12 inches of soil is �� mpi
2. Select allowable soil loadic� rate from table on page E-;
,P glad/ft'
3. Calculate adsorption width ratio by dividing rock layer
loading rate of 1.2U gpd/ft' by allowable soil loading rate;
1.20gpd/ft2+ -5-o gpd/ft2= a-V6 .
Check this value on page E-16.
4. Multiply adsorption width ratio by rock layer width to get
required adsorption width;
.IV. YoxL_ft=eft
��`�.•..,......••..•. �Ividth slily
� Lengih
Absllrpllun WWII Sir•InR"able
I'acalnlonv.+
I" Mhwut pv
lick IMPI`
Soil Tealwe
Galion
pn d.y per
rryare lwr
Wool
Alaarp,km . hhl
InNock Layer
Wkhh
FlKicr 11,an 0.1 •
Corse Sand
• •...
.....
0.1163
Saw 1
1.20
1.00
0.1 M 5 60
Fine Sand 0.
0 602.110
610IS
Sandy Lisa
0.79
1.32
1610.10
Loam
0.60
2.110
31 10 45
SIN Lora
0.50
2.40
4610 60
Clay Lawn
0 4S
2.67
60 10 120
Clsy
0.24
S.00
Sloweslhm
Clay,
_
_...
JIV..
U. UUWNSLUYE W&L 4VIUift
I. If landslope is 2.9 percent or less, basal width includes both the
' ape and downslope dike widths,
r♦
9
Ca, ate minimum mound size based on geometery:
a. )etermine depth of clean sand fill at upslope edge of rock
layer: Separation L feet
b. Multiply roc1, :. ; er width by landslope to determine drop �
in elevation; Sh �c difference
x crP % + 100 _ __Zjo_ feet �6w1lYO.r.Yw
c. Add depth of clean sand depth of clean sand for
separation at upslope edge (2a) to depth of rock layer to
rock depth and the depth of cover to find the total mound
height at Upslope edge of rock layer;
-L ft + 1 ft + 1 ft - 3 feet
d. Enter table on page bottom with landslope and upslope
dike ratio. Select dike multiplier of
e. Multiply dike multiplier by upslope mound height
to get upslope dike width: 4_ x -a_ _ _ /1 feet
f. Add the depth of slope difference (2b) to the upslope
height to get the downslope height _/ o i o feet
g. Enter table on page E-18 with landslope and downslope
.dike ratio. Select dike multiplier of Y, o ,
h. Multiply dike multiplier by downslope mound height
to'get downslope dike width! I_ x -3_ _ / y.- feet
1. Minirimum'mound width is the sum of upslope dike
width plus rock layer width plus downslope dike width;
/JL f t + /'.L ft+-,L ft= :? Yfeet
j. Subtract the Nlinimum width G.i from the Absorption
width F.4 to find the Additional Downslope required for
Absorption
/_ft-1,ft= C feet "F"°
k. Add the Additional Uownslope required for Absorptioi
to the downslope dike width and recalulate (lie Total
Mound Width whicli is is the sum of upslope dike
width plus rock layer width plus downslope dike width
eft+eft+PI, _ft feet
1. Total mound length is the sum of upslope dike width
plus rock layer I length plus upslope dike width;
l a• f t+ _ea 2. f t+ e f t= _Meet
�f--ToW length -----i
J 1
4:1
Lrownslups
5.1
6:1
f:t
J 1
kl
„1,c
&
&I
AI
6:1
sMisr
0
J.0
to
f.0
t0
� 70
10
4.0
IQ
t0
7.0
JA
1
JA
1.17
:is
!26
U6
1.11
1"
JAf
6.76
f.66
am
7.41
2
1It
f!6
t62
L14
1p
J20
631
J.16
t11
6.10
2
J20
/31
11.101
7!7
1.26
L75
10
I.Jf
5.01
L70
&AS
1
JAI
1.76
t2f
7.0
9.72
Uf
&aS
7
/ a
IL"
6.06
f
2M
f.0)
L67
am
on
3.61
333
4.s2
!.It
f21.
6
JAI,f.26
7.14
USN
2!1
J.22
tl1
t03
JAI
7
JAO
f!6
7.0
102/
IJ27
1Y
3.12
2.70
t2J
4"
2.13
J.t!
f.M
6.I]
I1S/
If.01
'.12
1.0/
J!7
1.in
to
IA1
0
4.11
t25
t.00
1J.111
It02
I'm
iN
3.63
3.10
/20
/A6
t0
420
to
10.0
Ism
2323
231
1"
J.11
3.73
6.12
444
11
IA6
7.14
11.11
17AS
NO
126
178
3.23
3.61
1"
421
11
sAt
7.60
1230
21.11
43.79
2.21
2.70
112
3.0
3.110
/0
1. Select number of perforated laterals 3
2. Select perforation spacing = _3 feet
3. Since perforations should not be placed closer titan 1 ft. to
the edge of the rock layer (see diagram), subtract 2 ft. from
the rock layer length.
(o a - 2 ft• = 60 feet
Rock layer lenslh
4. Determine the number of spaces between perforations.
Divide the length above by perforation spacing and round
down to nearest whole number.
Length perf. spacing = Go ft. + 3 ft. = ao spaces
(03) 02)
5. Number of perforations is equal to one plus the number of
perforation spaces .
coo spaces + 1 = 2 /_ perforations per lateral
6. Multiply perforations per lateral by number of laterals to
get total number of perforations.
3 Uj/ _
laterals x pefHAtlelal ` =� perforations
7. Determine required flow rate by multiplying
number of perforations by flow per perforation
. Pis x spn/pert
�Orau Cover
TeseeN
• Lorat of Oraledlle ►OWC
• lfwar load Lar« ' IMN low N M/ w w..
wla a IaeM p "I
-Pvrlw little otww ilea,
,
,•� ■ji ,
Aftj 1 R
-M L.MI It' le
of R«a Love,'
-pwfM.IMM Located of
Chao load Layer
BMW" N Lsoval
plslaal tall �ren1/1 lcarllld
seNre PIG" so" Grw
TABLH OF PERFORATION DISCHARGES IN
Head Perforation diameter Onchn)
r/N
1/a
sAa
0.56
0.74
1.5
0.69
0.90
2.Ob
0.80
1.04
2.5
0.89
1.17
3.0
0.98
1.28
4.0
1.13
1.47
S.0
1 1.26
1 AS
•Use 1.0 foot of head for residenlial system..
bUse 2.0 feel of head for other eslablishmenls
Table 2
1lissiafrra allowable number of floater lock Wa►ations prr
Isterol to ilvarantee -c I % nlackarle veriallun
M'� �;R +e•I"a
1.25 inch
1.5 inch
2.0 i
2.5
14
18
2
3.0
13
17
2,
3.3
12
16
2
4.0
11
15
2
5.0
10
14
2
B. If laterals are connected to header pipe as shown on upper
example, select minimum required lateral diameter from
table 2, enter table with perforation spacing and number
of perforations per lateral. Select minimum diameter for
perforated lateral - incites
9: If perforated lateral system is Attached to manifold pipe near
the center, as in lower example, perforated lateral length and
number of perforations per lateral will be approximately one
half of that In N 6. Using these values, select minimum JAMM i
diameter for perforated lateral from table 2�---
perforated lateral = --1--- incites
.. �w
A. Determine pump capacity:
Gravity Distribution
1. Minimum suggested is 6W 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 2,70()
gallons per hour (45 gpm) to prevent build-up of pressure in drop box.
Pressure Distribution 3
3. a. Select number of perforated laterals
b. Select perforation spacing = 3 (1.
C. Su trfft 2 fl. from The rock layer length.
2 It. it.
d. Determine the number of spaces betweetl perforations.
Len th perf. spacing - �_ f t. + L i It. = `■1 U spaces
C. spaces + 1 = �L ( perforations/lateral
I. Multiply perforations per lateral by number of laterals to
MEtotal gZ r of riper fo ati
x r�►� _ perforations.
g, !ja x _ gpm.
SELECTED PUMP CAPACITY Yr gpm
B. Determine head requirements:
1. Elevation difference between pump and point of discharge.
_Al feet
2, if pumping to a pressure distribution system, add five feet for pressure
required at manifold
feet
3. Friction hats
a. Enter friction loss table with gpm and pipe diameter.
Read friction loss in feet per I feet from table.
F.L = 3-;) it./100flofPiPe
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 tithes pipe length =
100 x 1.25 =
c. Calculate total friction loss by multiplying
friction loss in (t/IOU It by equivalent pipe length.
Total friction loss = �� -x I asp +1(X) _ feet
4. Total head required is the sum of elevation difference,
special head requirements, and total friction loss.
+ -I-�l
+ 7
111 (2) (3c)
TOTAL HEAD feet
Pump selection
I. A pump must be selected to deliver at least __J&f Spin (Step A)
with at least _L.J_ feet of total head (Step B).
END PER1 JRATION OF A PERFORATED LATERAL
Te►■eN
Lelrr N Ouu■W■ raD11a tar r
L SW L-1-1 N■rt 11, d her a 14'" CF Cd
oil%Ito "in ravel
-Pnlw.liwl O,Nled #W4-a.
�Mle C . Plea top
r
' 1 -N Lell I. Ed.• •l de. Loin
-►n1w.11ese Linter U
CIO" a wd Le»w Nl4w N Laeesl
alw+ 2N1 ►■creel/ Sewell"
Mlw. Pktkq Swill Lena
TABLE OF PERFORATION UISCHARCES IN CPM
I lead Perforation diermler (Inches)
r/n
1/1
l.0a
036
0.74
1.3
OA9
0.90
2.0b
0.80
1.04
2.5
OJ9
1.17
3.0
0."
Ila
4.0
1.13
1.47
5.0
116
1 bS
sUse 1.0 foot of head for sesidenuel syslenls.
bUse 2.0 feet of head for other establishments
Pipe Length
Point of 1T7ischarl
Elevation OHfcrence�
PKmp
F• 1 ab
1.5 inch 2.0 inch 3.0 inch
Pin AkUm lm prr 100 fl of alp
10
0.69
0.20
12
0.96
0.28
14
1.28
0.38
16
1.63
0.48
IS
2.03
0.60
20
2.47
0.73
0.11
25
3.73
1.11
0.16
30
5.23
1.55
0.23
35
7.90
2.06
o.30
40
11.07
2.64
0.39
4.S_
_14,73
3.28
0.48
50
3.99
0.58
55
4.76
0.7o
60
5.60
0.82
F-19
1. Determine Surface Area T
Wjdih
Rectangle = Area = L x W
2 x _ ,yT square feet Length
Circle = Area = x x (Radius)2
dius
3.14 x x = square feet 14.3
� = 14
Other = Get Surface Area from Manufacturer
square feet
Z. Calculate pajbns Per Inch
There arc - .,-, gallons per cubic foot of vc'ume, therefore you must multiply
the area times the conversion factor and divide by 12 inches per foot to
calculate gallons per inch
Area x, ..+ 12
+ 12 = ,gallons/inch /4A,Aj
Calculate Gallons to Cover Pump (with 2 inches of water covering pump)
(Height (in) + 2 inches) x gallons/inch
+x 0. 3 = 3 24 gallons
Calculate Total Pumpout Volume VReserve Caps
(Section 0 on page f-15) �y� I_r _ dv(O-Awk gallons —�viWAbm
Calculate Volume for Alarm (typically 2 to 3 inches) V Pump On
Depth (in) x gallons/inch =
a x = Y7 gallons Pump OR
Calculate Reserve Capacity (75% the daily flow) Pump Height
Daily flow (see page D-7) x .75 =
,ISO x .75 - _Z0 gallons
Calculate total gallons
gallons over ptun +gallons pumpout +gallo s alarm + gallons reserve
1 + 4 + 5 + 6 � %l�!
-3446 + �+ Y I + 6L O = gallons
Total Depth (Total gallon divided by gallon per inch)
Total Gallon+ allon/inch
-�- =- + _ inches
Float Separation Distance (equal total pumpout volume)
Total pumpout volume+ gallons/inch
4-gr+ ,P1.3 = if inches
Pumpout Volume
1ovn.niP ild, Fnnpe
'.mty, Minnesota
Of
0
.. �, `r
��M Rfa•il
S� T
LVF1T
Ai
B Al 6
�b
OVA
Xv /
o / gt// _
s �
,.
gj
'
P
5' ..
I IfnUly TJWAIM6' eAftmewr
/00
r , /
I h � J / •
I
n"esed To K Meek
pl ST.4NG�5
a.'-o
8
D_4' 44 "
PI
ND'
P-1
50 �
r�.
d Pt-v Teel V
' �" i A r-•e�iv�Nrr
L..w • K �r.
Proposed Garage Floor Proposed Lowest Floor
I / I
o I• II)AS
IProposed grades wlbjeet to resrlts of sell test.
Lot 6 uaek 1 PA1NITillS MOODS •
A
� enew� ri hwe rWs d ieseis w bAsw�r�n s+a� b � /
Redwood,cedar or
Water tight & lockable electric box
treated post (4x4 min)
Plugs or electric connections
All electric connections
2' PVC conduit schedule 80
made ins" box
Manhole cover chained 3 locked
Sealed manhole rings
Loop of power cord
6 space for stettlement
Final grade
Union At leas! 12'
below grade
Wire from power
supply
Pipe is laid on a uniform slope
Plastic rope or chain with
from pump station up to soil
anchor Do
treatment area for proper
Sealed tank cover
drainback
Alum float on separate
If pipe at tank must be lower
electrical circuit
than union to get elevation for
drainback, a 1 /4 inch weep
hole must be used
Start_ — — Q _ _ —�� — _
_ _ _ _ Weep hole
N,
Notes: Electrical wire from power supply
must not run over any tanks but
Shut-off level _ _ _
------- --
_ _ _ _ must be laid beside other tanks and
must be placed In conduit along post
Pump control float
Electrical cords from pump and
000 floats must be run through
conduit. Wires cannot have ground
contact.
Pumping rate should not exceed drop box outflow capacity or 45 gallons per minute
(2700 gallons per hour).
Pump discharge head must be adequate to overcome elevation difference between the
pump and distribution box plus friction loss in discharge pipe.
0
Frostproofing the discharge pipe
Place a rock envelope around discharge pipe.
Rock should be 314 to 2 1/2 inches in
diameter, with no sand. Cover with a 2
inch thick sheet of expanded polystyrene.
Wherever possible maintain a grass cover
over top of trench and allow snow to
remain in place. When snow cover is
light, place a 6 Inch hay or straw layer
on ground above pipe.
Backfill
Expanded
polystyre
6c
Discharge pipe
6'
Rock 3/4' - 2 1 /2' dia.
PERFORATED
LATERALS
SANDY LOAM SOIL
LAYER OF GEOTEXTILE •=
FABRIC OR 4 INCHES OF , ' y�
HAY COVERED BY
BUILDING PAPER
/ OR
PIPE FROM PUMP��
ell
CLEAN ROCK , .'�r ' �• „�" /' ; / DIVERSION FOR
• •••••�` :;�' ,� i' �� ,�
6" TOPSOILS � • = SURFACE WATER
�
•SIO
`�►. �~•'• " , �`� � �,� ,,ma�cc
91,
CAE
ND FILL SOD
pkENAYER
up
BARRIERRaL
SAYER
E-4
LAYER OF GEOTEXTILE LOAMY SAND CAP
FABRIC PERFORATED LATERAL
GRASS COVER 6 INCHES
CLEAN SAND FILL TOPSOIL
MAXIMUM SLOPE —�
3 TO I
CLEAN ROCK 4"
TOPSOIL PLOWED OR 3/4 TO 2 r/2 INCHES
DISKED SURFACE
SUBSOIL
CROSS SECTION A — A
PIPE FROM
PUMPING CHAMBER
w .n
Y
-• O
rr
PERFORATED '
L' ATFRALS -
BED AREA z
---- 0 w
� , I J
�I
I i W i W� m :'
-- ( z --- z � ,
I o o 20
INCH I v 'T "I INCHES _
DIKE --=0 FEET . I- DIKE
MAX.
TOTAL WIDTH
•
PLAN VIEW
PERCOLATION TEST DATA SHEET
a. in.
Percolation lest readings made by LO��' ����'�-ael+' n N ��starting at A do ela,U-J�
Test hole location_ Z o r G 1s l k I 4� 1 �" `'' :"ttole numL_. r�, Date hole was prcliarcNam,
Depth of hole bottom inches, Diameter of hole �* inches
Soil data from teat hole:
Depth, inches
UT
4
Soil texture
Method of scratching sidewal r %&-
Depth of gravel in bottom of hole Inches
11do
Date and hour of initial water filling%. Depth of initial water filling Z inches above hole baton
Method used to maintain at least 12 inches of water depth in hole for at least 4 hours_ A/A J (? i d
Maximum water depth above hole bottom during test / V— inches
Time
Time
interval,
minutes
Measurement,
inches
Drop in water
level, inches
Percolation
rate,
minutes PC -
inch
Rcmatks
.fir ,
s
Yd.c
C
Percolation rate minutes per inch.
x .
PERCOLATION TEST n2%T- MEET
0" . ;l.I Lt. V� '/tarting a'
Percolation lest readings made by pnIG`C) � � e
,� .���NO
%,b (� (�� % � �% Hole numbed. ^ I)atc hole was prcparc
Test hole location �—��
Depth of hole bottom._ inches, Diameter of hole inches
Soil data from teat hole: -
i._
Depth, inches
Soil textule
--
Method of scratching sidewall
Depth of gravel in bottom of hole —
Dale and hour of initial water Gllin a IL' Depth Depth of initial water fiinches above hole lwtlom
Method used to maintain al least 12 inches of water depth in hole for at least 4 hours &Ltld 3Q
, Maxitnuin water depth above hole Woom during test %";t— inches
`..
Time
Time
interval,
minutes
Measurement,
inches
Drop in water
level, inches
Percolation
rate,
minutes per
inch
Remarks
D
c
d
3. G
,L
Percolation tale = tinutes per inch.
PERCOLATION TEST DATA SHEET
on/�% Il Z OV starting ac "•yd a.m. n .
Percolation test readings made by (& J
Test hole locationZ4 (o S(k ( t"n �US�' LJA* S , dole number, Date hole was prepare /'*V*n2
Depth of hole bottoms - 2. inc hes, Diameter of hole inches
Soil data from teat hole:
Depth, inches
Method of scratching sidewalt S 6 .r k. �%a�, L.••S
Depth of gravel in bottom of hole inches
Soil texture
Date and hour of initial water fillings '� , Depth of initial water filling inches above (role buflom
Method used to maintain at least 12 inches of water depth in (role for at least 4 hours— Na�� '�• ��
Maximum water depth above hole bottom during test_ " 1 inches
Time
Time
interval,
minutes
Measurement,
inches
Drop in water
level, inches
Percolation
rate,
minutes per
inch
Remarks
or
26
c
ai
Percolation rates minutes per inch.
OM
PERCOLATION TEST DATA SHCI;'I'
Percolation test readings made by�f. on�i��1l�%� _ _starting.af l G—460.
f�rrl
Test hole location A, ( (31 ki i i,-� • v•��_ WOO- +,'No1e number, I)ale hole was prcpated
Depth of hole bolto __ / 2— inches, Diameter of hole (, Inches
Soil data fmm lest hole: •
Depth, inches
D —/l
Soil textwc
Method of scratching sidewall �� 015
DepUt of gravel in bottom of hole -
Dote and hour of initial water fillip , Depth of initial water filling / �-- inches above hole botlonr
Method used to maintain al least 12 inches of water depth in hole for at least 4 hours —
Maximum water depth stove hole tx,ttom during test 2"' inches
Time
Time
interval,
minutes
Measurement,
inches
Drop in water
level, inches
Percolation
tale,
minutes per
inch
Remarks
av
n
a�
-
Percolation rate minutes per inch.
0
019