HomeMy WebLinkAbout1977-05-19 Septic System Design ReportAn Expansion of Soil Engineering Services, Inc.
I7INNEAPOLIS/=T. PAUL 6800 S. County Rd.18, P.D. Boll 35108, Mpls., Mn. 55435 / 612-941.5600
NORTHERN MINNESOTA 3219 E.19th Avenue, Hibbing, Mn. 55746 / 218.263.9869
May 19, 1977
Nitz, Inc.
1989 Fagerness Point Road
Wayzata, Minnesota 55391
Gentlemen:
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ENGINEERING TE311NG
1. S. aRAUN P, E.. PrwWnr
P. H. ANGERSON, Vier Pars. Opwsriwr
C.G. KRUSE V E. V" Prat Enpr ,,V
Re: 77-159 SOIL BORING $ PERCOLATION
TESTS
Lot 3, Block 1
Farview Addition
Trono, Minnesota
As requested, we have recently conducted a soils investi-
gation consisting of one power auger boring and 8 perco<
lation tests taken to determine the general soil and water
conditions, as well as to provide information relative to
the soil absorptivity rates. The boring and percolation
tests were taken at the locations shown on the attached
sketch. Field locations were determined by our crew as
referenced to the house location. Surface elevations were
referenced to a spike in the south end of an 8-inch ash,
located on the northeast side of the proposed house. The
elevation at this pc_nt was assumed equal to 100.0 feet.
Initially, six percolation tests were conducted on the lot
on May 4, 1977. As some of the tests indicated failing results,
two additional percolation tests were conducted on May 17, as
you requested.
INVESTIGATION METHODS:
The power auger boring was completed using a truck -mounted
power auger unit. The soil classifiations and depths shown
on the attached log were inferred from the soils brought to
the surface by the continuous flight feature of the auger.
The depths of strata changes are, thus, considered approximate,
CONSULTING ENGINEERS/SOILS AND MATERIALS
Test Borings • Foundation Engineering and Recommendations • Inspecuan of Construction • Material Testing of Soils. Concrete and Building Components
77-159
Nitz, Inc. -2- May 19, 1977
Mineral soils encountered in the boring were classified in
accordance with the Unified Classification System (ASTM
D2487). A copy of that chart is attached. Representative
samples were then returned to our laboratory for verifica-
tion of the field classifications by a Soils Engineer.
Representative samples will remain in this office for a
period of 60 days to be available for your examination.
The boring was probed immediately after its completion to
check for the presence of groundwater. The boring was also
rechecked prior to leaving the site. The absence of ground-
water was noted in both probings of the borings to its 20
foot termination depth.
The percolation tests were run in 6-inch diameter holes
drilled to an approximate depth of 36 inches, in accordance
with the procedures recommended by the Minnesota Department
of Health (MHD) and with the procedures recommended by the
City of Orono. In accordance with these procedures, the
bottom and sides of the holes were scratched with a knife
blade to remove any smeared soil surfaces and to provide a
natural soil interface into which the water may percolate,
Two inches of coarse sand was then placed in the bottom of
the holes to prevent scouring. The holes were then carefully
filled with clear water to a minimum depth o: 12 inches over
the top of the sand layer and allowed to soak overnight with
the percolation tests being conducted the following day.
RESULTS:
The log of soils encountered in the boring and the water
level observations are shown on the attachec Log of Boring
sheet.
The soil boring and percolation tests generally encountered
sandy clay glacial till from the surface to the 10-foot
depth with the top 1 foot being considered the topsoil
layer. Immediately underlying the glacial till, a fine to
medium -grained glacial outwash sand was encountered to the
20-foot termination depth of the boring.
Results of the six initial percolation tests indicating the
soil absorptivities in minutes per inch (mpi) are as follows:
HRAun"
ENGINEERING TESTING
77-159
Nitz, Inc. -3- May 19, 1977
Surface
Soil At
Rate
Test #
Elevation
Test Depth
m i
P-1
95.0
Sandy Clay
(CL)
120
P-2
92.8
Sandy Clay
(CL)
48
P-3
93.5
Sandy Clay
(CL)
120
P-4
90.0
Sandy Clay
(CL)
120
P-5
87.3
Sandy Cldy
(CL)
35
P-6
86.0
Sandy Clay
(CL)
34
The average of these 6 initial percolation tests are then 80
mpi.
As indicated to you in a telephone conversation, percolation
tests P-2, P-5 and P-6 met the percolation requirements
while tests P-1, P-3 and P-4 indicated values outside the
limits for a typical individual sanitary sewer system. At
that time, in our opinion, it appeared likely that a suitable
drainfield site can be located in the lower area somewhat to
the south of the present proposed location as indicated by
tests P-5 and P-6 and on the boring where suitable granular
soils were encountered at or near elevation 83±.
At your request, on May 17 two additional percolation tests
(P-7 and P-8) were performed, approximately 30 feet further
south than the location of P-5 and P-6 and both were conducted
at or near elevation 81± per the assumed datum. Readings
were taken on these two additional percolation tests on May 18
with the following results:
Soil At Soil At Rate
Test !# Test Depth Test Depth m i
P-7 81± Slightly Silty Sand (SP-SM) 10
P-8 81± Slightly Silty Sand (SP-SM) 10
REMARKS:
In our opinion, a suitable drainfield can be situated imme-
diately to the south of the proposed location with the start
of the drainfield at or near the location of percolation
tests P-5 and P-6 and running parallel to the downslope
contours to the southeast of the proposed house location.
Of necessity, the area of the power auger boring and perco-
lation tests in relation to the area of the proposed drain -
field and the depth of the boring are limited. Suggestions
and/or recommendations of this report are opinions based on
the data obtained from the boring and the tests.
BRAun'
ENGINEERING TESTING
77-159
Nitz, Inc. -4- May 19, 1977
If we can be of further assistance in evaluating these data,
or in developing a sanitary system layout for the lot,
kindly contact us at your convenience.
Very truly yours,
gUN:LENGINEERI TESTING, INC.
Dennis Rietschel
e-%%,. Engir rWg Assistant
!Braun, P.E.
sident
DMR/JSB:skf
' The content of this report an , --rpporting document., are for the exclusive use of the addressee in the absence of our prior written approval
we make no rep resents Uon ..*.-' assume no responsibm'y to any other parties regarding such content
BRAUH"
ENGINEERING TESTING
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LOG OF BORINGS
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11
PROJECT: 77-159 Soil Boring b Percolation Test
DATE: 5/4/77
Lot 3, Blocc 1
SCALE: 1"-4'
Fairview Addition
Orono Minnesota
BORING: B-1
LOCATION:
BORING:
LOCATION:
See Attached Sketch.
R .E EV•
SURF. EL EV:
93. 3
Depth
Description o Ma erials
2487
WL
De t
Des cr phon o term!; ! 7
WL
SANDY CLAY, dbrown,
1
moist To soi
CL
SANDY CLAY, with fine to
medium Gravel, brown,
CL
moist.
(Glacial Till)
10
SAND, fine to medium -
grained, with fine to
medium Gravel, brown,
SP
moist.
I
(Glacial Outwash)
,
20
Water level not encountered
when probing boring
immediately after with-
drawal of auger.
An Expansion of Soil Engineering Services, Inc
ANNEAPOIIS/ST. PAUL 6600 S. County Rd.16, P.O. Boa 35100, Mpis., Mn. 5$435 / 612.941.5600
ORTHERN MINNESOTA 3210 E. 19th Avenue, Hibbing. Mn. 55746 / 216-263.6669
june 9, 1977
Nitz, Inc.
1989 Faegerness °oint Road
Wayzata, Minne d 55391
G._ntlemen:
Hmult
ENGINEERING TESTING
s aeapwr t. Arar.a►nr
r w .wotltsow. V,n
c G U. I. E Vi Ara E,rrrr ,m
Re: 77-159 $ 77- .99
Proposed Drainfield System
Lot 3, Block 1 $ Lot 4, Block
Farview Addition
Orono, Minnesota
As requested, please ad copies of the proposed drainfield
systems for the above mentioned lots. The systems were set
up based on the results of the recent percolation tests and
in accordance with the "Code of Minimum Standards" as set
forth for individual sewage disposal systems for the Village
of Orono.
The Village of Orono recommends •t each single family
residence shall be equipped wit.. o septic tanks, the first
of which shall not be less than 750 gallon capacity and the
second tank not less than 500 gal�on capacity. If garbage
disposal units are used, the first tank shall be of 1000
gallon capacity. The location of the disposal drainfield
shall be in an unobstructed and preferably unshaded area and
shall be placed no less than 10 feet from.occupied buildings.
property lines, or buried p-pe, distributing water under
pressure and 75 feet from any water supply well or buried
water suction pipe. Disposal trenches shall have a depth of
24 inches and not j exceed 36 inches. Trench width shall
be 30 inches and with 7 feet center to center minimum
spading of lines.
Lot 3, Block 1: The disposal system designed for Lot 3,
Block ylerTs residence) was set up based on the results
of percolation tests P-5 through 1'-8, which indicated an
average of 22 minutes per inch (mpi). For this system, a
total of 220 li:.-al feet of absorptive trench per bedroom is
then necessary. Based on a 3-bedroom home, a total of 660
lineal feet of absorptive trench was then utilized in the 7
design of the system. In order to n.eet the minimum require-
ments, the design system consists of 5 trenches, S5 feet in
CONSULTING ENGINEERS/SOILS AND MAIERIALS
Test Elonngs • Foundation Engmeennq and Recommer—axons a Inspection o; Construction • Material Testing of Smis. Concrete and Building I ompenents
77-159 & 77-199
Nitz, Inc. -2- June 9, 1977
length and located on the southeast side of the proposed
house with the trenches running, parallel to the downslope
contours, as shown on the att.,.bed sketch. The optional
location per the sketch was ,.nc -ded doe to its possible
easier accessibility.
Lot 4, Block 2: The system designed for Lot 4, Block 2
(McCrath residence) was based on the results of percolation
tests P-5 through P-8, which indicated an average of 42 mpi.
For this system, a total of 290 lineal `-et of absorptive
trench per bed -Dom would be required, efore, the drainfield
system consisting of '70 lineal feet of .)sorptive trench
was &.Agned 'based o- a 3-bedroom home for this lot. In
order to meet this requirement, six absorptive trenches S8
feet in length starting approximately 60 feet southwesterly
of the proposed southwest house corner and as shown on the
attached s?.r h, appear suitable for this lot.
It has beer,:ar pleasure to be of service to you on these
projects and if we can be of further assistance in evalu-
ating the enclosed data, kindly contact us at your convenience.
Very ;rely yours,
RALA ENGINEER. G TESTING, INC.
�Denn, M. Rietschel
ErtginLeriI4 As 'stant
• /_
C. G. Krus
Vice President - Engineering
r'MR/CGK: skf
rh, cc itrot of this report And supporting documents air for the enclustve use of the anrne»re In IM absence,-t our poor wr.nen approval
we make nu reprrsentahon And assume no it Yphad, to any othm parbrs regarding such conlrnt
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ENGINEERING TESTING
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