HomeMy WebLinkAbout1985-05-20 Septic System Design ReportSYSTEM DESIGN
FOR GARY RODERICK
LOT 7, BLOCK 1, RINGERSWOOD
ORONO, MINNESOTA
5-20-85
1. Percolation Rate, Ty,<, J System.
Percolation tests were. taken previously by others. ltwever, the proposed
house is on the primary si-Lie' tested earlier. Thus, we took new percolation
tests for a primary site and had an average percolation rate of 25.2 M.P.I.
but a high water table re:uiring a mound system. Tests were done at an 18"
depth because these upper layers would be used for the proposed mound
syste. The old alternate site should still be preserved for possible future
use.
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 feet
wide by 50 feet long.
4. Septic Tanks and Distribution System.
Two septic tanks of 1000 gallons each are recommended. In addition, a third
pumping tank will be seeded to house the pump required for pressure dis-
tribution 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 o' Orono.
5. Mound Dimensions.
(Ise a 2.67 factor x 10 feet of rock bed width or 26.7 feet for the basal
width. Since the ground slope is between 1.5 to 2.5 %, both the upslope and
downs!ope areas can be used. % wever, with a 3 foot high mound and 4:1
sideslopes, the total width would oe 10 feet for the bed plus 11 fcet
upslope and 13 feet downslope or 34 feet which should be used rather than
the 26.7 feet.
If there are any other questions, please contact me.
Sincerely,
PERCOR, INC.
Mark S. Gronberg, P.E.
f
WILLOW DRIVE
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CITY OF ORONO
GENERAL CONSTRUCTION REQUIREMENTS
MOUND DRAT_NFIELD SYSTEM
TO BE 1'3ED WHERE: Seasonal perched water table is between 2 feet and 4 feet
below surface. Percolation rate in top 12" of soil is
faster than 60 MPI. Percolation rate in subsoil but above
water table is faster than 120 MPI. Where percolation rate
is 60-120 MPI, depth to groundwater shall be at least 3'
and slope must be no more than 3%. Where percolation rate
is 30-60 MPI, depth to groundwater shall be at least 2'
and slope must not exceed 6%. If percolation rate is faster
than 30 MPI, depth to groundwater shall be at least 3, and
slope must not exceed 6-12%.
CONNECTION TO
HOUSE House to tanks may be PVC (ASTM P-3034 or better),
cast iron or clay tile. PVC should be sand -bedded
in flat runs over long distances. No outside air test
required but joints must be tight.
TANKS Two (2) precast concrete tanks are required. Min. size
1000 gal. and 750 gal.; we recommend 2 1000's. Tanks
must h,ve 20" manhole riser to within 12" of final
grade, and at least one 4"-6" inspection stack to
surface. Baffles .crust he acid resistant and may be
Plastic, fiberglass, or precast with tank.
DRAINFIELD Mound consisting of 12-24" layer of sand on plowed, chopped,
or otherwise scarified natural surface soil. 12" rock bed
on top of sand layer, 10' maximum width X length dependent
on water use. Distribution pipe is laid in top 3" of rock.
Cover rock bed with s„raw or hay AND building paper. A
layer of sandy loam 6-12" thick should be placed over the
covered rock bed and a 6" layer of topsoil then placed over
the sntire mound. Finished sideslopes to be 3:1 or flatter.
Grass cover should be establishes as soon as possible over
the n.ound area to reduce erosion and aid in evaporation.
THE MOST IMPORTANT STEP IN CONSTRUCTING A MOUND IS
PREPARING THE NATURAL SOIL SURFACE BY DISC -PLOWING
OR CHOPPING WITH A 3ACKHOE TO A DEPTH OF ABU%;T 12".
When sand is pushed or dropped onto this loosened raw top -
boil (DON'T drive on it), an interface is formed which will
allow percolation to occur from the sand into the topsoil.
SEE "WETCH ON BACK 0? THIS SHEET.
DISTRIBUTION The mound must use pressure distribution and requires a
pump from the se tic tar. s. Distribution must be 1ln" PVC
or plastic with �" holes (turned down) every 36". Pumping
from a 2" manifold, distribution system st.ould be 3 lengths
of pipe spaced 40" on center capped at the ends, running
the length of the rock bed (see sketch). No drop boxes or
distribution boxes are used. 4" PIPE WITH GRAVITY DISTRIB-
UTION IS NOT A17CEPTABLE IN A MOUND SYSTEM.
PUMPING Pump should go in a 3rd tank or in a baffled chamber of
2nd tank. The idea is to retain the 2nd tank's capacity
for solids retention. An alarm device and reser,re capacity
equal to one days sewage flow .-+
are required. /SO CA.Q /13r, A
�4ZC�RFVCAekCIT`f rvNAY /AlJCLE 1.lG%L'FQD SPRcf AA0vF -rAv% pe- e),4 -L67-
64PYL' L- .
TYPICAL '}K_v.1pl syiAGL MEATKr T LYSTFA LAYMT
4 INCHES S74AW OP MARSH SANDY LOAM SOIL 6-12" F
HAY AND LAYER OF RED des
ROSIN PAPER PERFORATED LATERAL
GRASS COVER
12-24' SAND FILL 6 INCHES
TOPSOIL
MAXIMUM SLOPE —.-
3 TO I /
_ OPS IL__-----
r—Pl01MED OR `—CLEAN ROCK 5' MOW FIPB, 2" 0�'E74
DISKEr SURFACE
CROSS SECTION A -A
PIPE FRr,M
PUMPING CHAMflER
II
� F
ROCK BED -
1 I SH Ho". _ 10'a 40,
S BR 4ome - 10'j 65,
4" FYC (•
PERFORATEC I RtT=.tO LL - IROM
LATERALS I ( ROC FD Of
t" Sol." a d S F.S.
*Very )6"
EXrcr,7 of
I i Sp, ,D r/c.L
ED AREA u
- TO 2'1, -4
CLEAN INCHESROCK'
j 12,. DeKF i rr A (eYouR
20 r6l^A)44 *f-
- INCHES -�
SA�t 10 FEET _S4r.n
FAA �1n-'�-X 10'Wfn`
lOC4 111S
Ov[! App
01,
PLAN VIEW
QUESTIONS ? CALL THE S 3PTIC SYSTEM INSPECTOR AT 473-7357-
B- 35
PERCOLATION rLST DATA SHUT
Test hole 'location iq 19 Fir Role number
Date test hole was prepared / — X Depth of hole bottom, /e�inches.
Diameter of ho)e,_ inches.
Soil data from r.Lst hole:
Depth, inches Soil texture
-/l 13Z4e_ 4 o�f/`1
Method of scratchlne s.dewall _ s , e,4
✓Ep:h of pea -sized gravel in bottc= of hot ?, inches.
Date and hc::: cf _nitia. water f!:li,&
Dep:h c` initial -.:atx. fill`ng, inches above hole bottom.
`god ucLd to nainta'.r at least 12 inches of water depth in hole for at least
L
Pe.cclatior, test readings made by 1)e,4J 6-f'd/!J on
a.m.
starting at M. . Maximum water depth above hole bottom
(date)
during -est, 7�_ irchcs.
"ise i
:ze :nter�al, i Heasuremen :, Drop in water
!!inu:es { inches I level, inches
ti L L
Percolation
ite,
a.:nutes per
i:,ch
Remarks
-LILL
LPL
L
y
S
27
3
4
Percolation rate • Y. 0 minutes Per inch.
PERC01.AT10N TEST DATA SHM
Test hole loc:ation__ /f n4L'o C �� Role number
P.:e test hole was prepare:: Depth of hole bottom, inches.
Diameter of hole, f/_ inches.
Soil data"from test hole:
Depth, inches Soil texture
r
hethod 0 ratcfing sidewall �/0/1 ( A t R
Depth of eez-sized gravel in bottoz of hole, 2 inches.
;late and hcur of initial :titer f:1ling 1-/7 — S' 4:" - 7.
Jep:h c_` ini:iai water filling, / A6 inches above hole bottom.
Xcthod used to =ainra'_n at least 12 inches of water depth in hole for at least
4 hours :" l / •L l
Per--latioc test reacings Lade by �%D/f/G"'/'� /+!�lrf / on
,i -/•C'� <1� S starting or e'm' Maximum water depth above hole bottom
(date) Y.M.
dur'_ng :est, in_hes.
;ise
Time i inte-.•al, 4easuremen Drop in water ,
!:mutes i inches level, inches
Percolatior
rate, �
minutes per
inch
Remarks
23
1L
-r
7-1sr
.�
Z
Igy
Percolation rate 6 alnutes per inch.
PERCOLATION TLST DATA SHUT
s- 35
Test hole to atior_ / ) /) �;Y/(� Bole number
Datr test hole was prepared Depth of hole boctoW,_� inches.
Diameter of hole, _�_ inches.
Siil data from test Dole:
Depth, inches Soil texture
-L '
Method of scza:ch',rq sidewall `
:E?th of Yea -sized gravel in of hole, Z inches.
gate Enc hcc:r of _.._tial rater fi:'_inF
Jep:h of iritial water filling, inches above hole bottom.
Mczhoe used to maintain at least 12 inches of water depth in hole for at least
L hours Lr- F/ L l
Percolation test re&dings made by on
starting at a'm' Maximum water depth above hole bottom
(date) --p.m.
curing :est, % /2 inches.
rime
size i interval, Measurement, Drop in water
Minutes inches I level, inches
elo Z—
Percolation
rate,
minuses per
inch
Remarks
, . , ,.
7
?t rcolation rate - 97, 0 minutes per Loch.
s- 3s
PERCOLATION TEST DATA SHUT
Test hole location_ f -i /) FW,/ (R Bole number
Date test hole was prepared J_ -- / 4 — G'C' , Depth of hole bottom, / inches.
Diameter of hole, �1 inches.
Soil data.from test bole:
Depth, inches Soil texture
Method of scratcrinR eidewall _,�",4Tc f+ --R
✓cpth of pea -sized gravel in bo:tez of hole, 2 inches.
Date ane hc:.r cf initial :titer firing S—/7-- Lr 7 /,_
Depth cf initial water filling, 116 irches above hole bottom.
Mcthod used to m.aintair at least 12 inches of water depth it; hole for o least
4 hours v__ f /'L L
Percolation test readings aade by b i/:/ ��; /t'%ic',�-C on
starting at a'm' . Faximum water depth above hole bottom
(dame) .m.
during zest, iIILhEs.
I
.i=e
lr.terva2 , HeasUreme. , Drop in water
K:nutes i in-hes level, inches
Percolation
rate,
minutes per
inch
Remarks
L /
7
%
t I
J
Percolation rate - /,". - alnutes per inch.
Logs of Soil Borin .s IS-l8
o•�����
(.oration or Project—_-
1
Bor inns made by �L.�Oi?% �-� ' / •'!.� t" %l. /' te—
Classification System: ASH(? USDA-SCS Unified : other — —
Auper used (check two): Nand or Power _; Flight _, or Bucket X other
Depth. I Boring number _ — _1 Depth, Rorinp number
In
!in Surface elevation °eet Surface elevation —`gzz
&A? -c• c' r A � : r.,t' • t
�,4i! t �/r'✓r.�.�- Cal � y
End of boring at —�71 feet.
Standing water table:
Present at I feet of depth,
hours after boring.
Not present in boring hole
Mottled soil:
Observed at 2. 3 feet of depth.
Not Present in boring hole
Obs,rvations and co*nents:
Ilt a.N' � lA Y
3 --
4
5 —
6 —
7 —
8 —
End of boring at L,/ fe
Standing water table:
Present at �. feet of depth,
,340 hours after hurina.
Not present in borino hole
Mottle, soil:
Observed at z • oQ feet of depth.
•c present in boring hole
iservations and comments:
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