HomeMy WebLinkAbout1978-02-13 Septic System Design Report' An Expansion of Soil Engines ing Services, Inc.0mun-
ENONEERM TESTMrO
'O MINNEAVOLIS/ST. VAUL 6680 S. County Rd. 18, V.O. Box 36108, Myb., Mn. 56435 / 612.941-SM 1 a axAU%F. E.. AseuAnr
❑ NORTHERN MINNESOTA 3219 E. 19tb Awnw, Hibbing, MN. 56746 / 219.2634M 1,N ANOEnEOa, VbAm Operations
O CENTRAL MINNESOTA 200 Owo Awnw No., St. Cloud, Mo. 5=1 if612.253.9940 C O. KxUU P. E., V"Flat Ee A@W.V
February 13, 1978
Mr. David Nitz
464 2nd Street
Excelsior, MN SS331
Re: 78-08B SOIL BORINGS & PERCOLATION
TESTS
Lot 8, Block 1
Brown's Residence
Farview Addition
Orono, Minnesota
Gentlemen:
As you requested, we have recently c-zducted a series of two
power auger borings and 21 percolat i tests in an attempt
to evaluate soil absorptivity rates tor an individual sanitary
system proposed for the above referenced lot.
The boring and percolation tests were taken at the locations
as shown on the attached sketch. Field locations were
determined by our crew with reference to the staked property
corners. Surface elevations were referenced to a top -of -
block marker set in a tree on the property line approxi-
mately 20 feet north of the southeast property corner. An
elevation of 100.0 was assumed for this bench mark.
Initially, six percolation tests were conducted on the lot
' on January 6, 1978. At that time, all of the testL indi-
cated failing results. As you requested then, six addi-
tional were conducted slightly upgrade and farther to
the north of the initial tests. Three of these tests numbered
P-2, P-10 and P-12, all were within the minimum requirement
for a drainfield. The three tests conducted further to the
east in this series, however, all failed to meet the criteria
for an adequate drainfield system. Subsequently, three
additional tests were then conducted to the west of the
' three passing tests; however, these three also failed to
meet the 60 mpi requirement. Six additional percolation
tests and an additional soil boring were then conducted on
' February 9 in the area of the northeast portion of the lot,
results also indicating this area to be unsuitable for a
drainfield.
1 CONSULTING ENGINEERS/SOILS AND MATERIALS
Test Borings - Foundation Engineering and Recommendations - Inspection of Cc ruction - Material Tasting of Soils. Concrots and Building "omponents
78-08B
Mr. David Nitz -2- February 13, 1978
The percolation tests and the borings were either conducted
with a truck -mounted power auger unit; or, in those areas
inaccessible to truck, with a hand operated drill. All
operations were c..►ducted in conformance with City of Orono
specifications and in accordance with those procedures as
indicated to you in previous percolation test reports
conducted for various lots in the addition.
The borings were probed immediately after their completion
to check for the presence of groundwater and once again the
following day. Groundwater was encountered at the 4-foot
depth in boring B-1, however, was not enc untered at the
time of the final reading in boring B-2.
RESULTS:
The log of soils encountered in the borings and the water
level observations are shown on the att:+.h,2d Log of Boring
sheets.
Soil boring B-1 generally encountered a frozen silty clay
topsoil to a depth of approximately '.�j feet, underlain by a
silty clay lacustrine deposit to a depth of 8 feet. Silty
clayey sand glacial till was then encountered to the 17-foot
termination depth in this boring. Boring B-2 encountered a
silty sandy clay topsoil from the surface to approximately
the 1h-foot depth. A sandy clay glacial till was then
encountered immediately below this layer to the 8-foot depth
where a silty clayey sand till was then encountered to the
20-foot termination depth in the boring.
The results of the percolation tests indicating the soil
absorptivities in minutes per inch (mpi) are as follows:
Surface
Soil At
Test N
Elevation
Test Depth
P-1
92.5
Silty Clay (CL)
P-2
93.5
Silty Sand (SM)
P-3
92.3
Silty Clay (CL)
P-4
91.3
Silty Clay (CL)
P-5
92.2
Silty Clay (CL)
P-6
92.5
Silty Clay (CL)
P-7
91.8
Silty Clay (CL)
P-8
98.4
Silty Clayey Sand,
(SM- SC)
P-9
92.6
Silty Clay (CL)
P-10
96.9
Silty Clayey Sand,
(SM-SC)
Rate
m i
80
30
120
240
80
75
40
BRAUR"
ENGINEERING TESTING
78-08B
Mr. David Nitz
Test N
P-11
P-12
P-13
P-14
P-15
P-16
P-17
P-18
P-19
P-20
P-21
Surface
Elevation
9i. 2
94.8
94.1
93.5
94. 7
10S. 8
10S.4
106.7
107.6
105.9
107.2
-3-
Soil At
Test Depth
February 13, 1978
Rate
Lmp ij-
Silty Clay (CL)
Silty Clayey Sand,
(SM-SC)
Silty Clayey Sand,
(SM-SC)
Silty Cl.,y (CL)
Silty Clayey Sand,
(SM-SC)
Sandy Clay (CL)
Sandy Clay (CL)
Sandy Clay (CL)
Sandy Clay (CL)
Sandy Clay (CL)
Sandy Clay (CL)
*No drop in water level observed.
60
120
240
120
*
480
*
*
*
480
As shown above, only three of the 21 percolation tests
conducted on the lot met the specified minimum standard
required for a drainfield system.
As noted, some of the areas indicated passing results while
no water movement was observed in other areas. This variability
in the test results can probably be attributed to one or two
factors. Soils in the test holes, particularly in the lower
areas, appear to range from silty clays to silty clayey sand
which would influence the percolation rate. The more cohesive
sandy clays and silty clays would typically have higher
percolation readings.
The failing rates may also be affected by frost action.
Although frost depth throughout the site appears to be
somewhere between 1 and 2 feet below the surface, temperature
measurements on another lot in Orono conducted February'll
indicated that the soil temperature at the 36-inch depth
was 320 F. If the water does not freeze when entering the
soil, it would be considerably more viscuous, which would
limit its flow through the soil pores.
PRELIMINARY RECOMMENDATIONS:
In a recent telephone conversation with Mr. Mike Gaffron,
Septic System Inspector from the City of Orono, we have
indicated that a potential drainfield system can likely be
established on the lot in the area immediately to the west
of the house, based on percolation tests NP-2, P-8, P-10,
and P-12. The City has asked that we make a preliminary
BRAUR'"
ENGINEERING TESTING
78-08B
Mr. David Nitz -4- February 13, 1978
design for a system in this area, subject to change, based
on percolation tests run next spring. However, it would be
based on a rate of on the orda rof 80 mpi, which is above the
normal minimum acceptable standards.
Although standards have not been set up for developing a
system based on an 80 mpi rate, a larger than normal system
consisting of seven 30-inch wide trenches, 75 feet in length,
with 7 foot center -to -center spacing may be adequate for
this system. This rate was interpolated from the standard
curve system which indicates requirement rates per bedroom
based on the minutes per inch reading. Based on this system,
a typical 4-bedroom home would then require approximately
325 lineal feet of absorptive trench per bedroom.
Although a system of this stature appears feasible, there is
some risk of future failure.
A sewage treatment mound would be the second alternative for
the site. With this system, sand and rock fill can be
placed directly on the natural clayey soils in the proposed
drainfield area. It should be noted that general topography
in this area should be relatively flat, with less than 3t
grade slope. This system would be developed based on 125
square feet per bedroom or .83 square feet per gallon of
waste per day. For a proposed 4-bedroom home, the mound'bed
would require 500 square feet of total area. This can be
accomplished with a bed length of 50 feet and a maximum
width of 10 feet. The system then consists of approximately
12 inches of sand fill overlying the natural soils. A 9-
inch layer of 3/4 to 2�-inch clean rock is then placed
directly over the sand and used as a bedding for the pipe.
A sandy soil should then be placed over the pipe, the thick-
ness of which should be between 6 and 12 inches. A 6-inch
layer of topsoil would then be placed immediately over the
sand. The sideslopes of the dike should not be steeper than
3 feet horizontally to 1 foot vertically.
If either of the two above systems are not feasible for the
lot, a third alternative would be a sewage osmosis system.
The sewage osmosis system can be useful in areas of heavy
clay soils and in areas where the seasonal water table is
high. This patented system, using a set of cathodes and
anodes, together with the special drainfield trenches,
should be designed, constructed, and maintained by a licensed
dealer. This system, as well as those mentioned above, are,
of course, all subject to City of Orono approval.
s�un
EN(i1NEERINQ TESTING
1
78-OSB
Mr. David Nitz -S- February 13, 1978
' It is recommended that additional percolation tests be
conducted after the spring thaw in the event that frost
action is, in fact, contributing to the failing results.
' If this proves to be the case, a more suitable drainfield
system could then be developed on the lot.
' Should you have any further questions regarding these data
or if we may provide further services on this project,
kindly contact us at your convenience.
Very truly yours,
;UN ENGINEERING TESTING, INC.
Dennis M. Rietschel
io
�En. gineeI�rr'ng gist
PVice President - Engineerilig
DMR/CGK:skh
' The content of this report end supporting documents are for the exclusive use of the addressee In the absence of our prior written approval
we make no representation and assume no responsibility to any other parties regarding such content
BRAUR
ENOWERING TE8T1N0
tiN�4�tl�it iNT�L F1EY.
! ol40
BRAUR"
ENGINEERING TESTING
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WA MINW,
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LOG OF BORINGS
PROJECT: 78-008 Soil Borings S Percolation Tests
DATE: 1/6/78
Lots 3 and 10, Block 1, Farview Addition
SCALE: V-4'
Orono, Minnesota
BORING: B-1 LOCATION: Lot 8,
BORING: B-2
LOCATION:
R Block 1, See Attached
See Attached Sketch.
R
92.2 Sketch.
107.1
Depth
AS
De scr
148
ion o Materials
ASTM
D2 87 WL
DepthDescr
ono Al MaterialsD2487
ASTM
W
SILTY CLAY, black,
CL
SILTY SANDY AY, black,
1.5
frozen. (Topsoil)
1.5
frozen. (To P
(Topsoil)
CL
SILTY CLAY, dark brown,
SANDY CLAY, with a trace
wet.
of fine to medium
CL
(Lacustrine)
CL
Gravel, brown, moist.
(Glacial Till)
8
8
SILTY CLAYEY SAND, fine
SILTY CLAYEY SAND, fine
to medium -grained,
SM-SC
to medium -grained, with
SM-SC
grayish brown, water-
a trace of fine to med1wi
bearing.
Gravel, brown, moist to
(Glacial Till)
wet.
(Glacial Till)
17
Water level down 8' 10
minutes after completion of
boring.
20
Water level down 4' 24
Water level not encountered
hours after completion of
10 minutes after completion of
boring.
boring.
Bench Mark - Top of block
Water level not encountered 24
marker in tree located 20'N
hours after completion of
of N.E. property corner with
boring.
elevation assumed - 100.0'.
DESCRIPTIVE TERMINOLOGY
PARTICLE SIZE IDENTIFICATION
"AdtMs
over 3"
Cke
Come
1 " — 3"
Medium
1/4, — 1"
Fine
No. 4 — 1/2"
Send
Coro
No. 4 —No. 10
Madum
No. 10 — No. 40
Fine
No. 40 — No. 100
Very Fine
No. 100 — No. 200
Salt
No. 200 — A01 mm
Clay
leN then A01 mm
h _ , ATI VE DENSITY OF
COHESIONLESS SOILS
WV lopes
0 — 4 8PF
boo
S — 10 MF
madam dense
11 — 30 9PF
dew
31 — 60 S►F
very dense
SO► MF
RELATIVE PROPORTIONS
SOIL INTRUSIONS
THICKNESS
stern
1 IS" — 1 "
Inver
I" — 12"
vervad
alternating teeny Of
lenses of clays and
silts in lake deposit
MOISTURE CONTENT
Dry
law than S%
Moist
sandal optimum moisture
Net
ovar optinwm noisture
Wl.nrbsering saturated send
CONSISTENCY OF
COHESIVE SOI LS
very soft
0 — 1 S►F
soft
2 — 3 SPF
rather colt
4— S BPF
medium
6— 6 SFF
rather stiff
S — 12 BPF
stiff
13 — 16 BFF
very stiff
17 — 30 5PF
hard
30+ S►F
RELATIVE ►RO►OMYOINE
with a few 0 — 10%
with sorrel 11 — 20%
with over 20%
ORGANIC CONTENT
0 - S%
non to slightly organic
6 — 10%
slightly organic
11 — 26%
organic
26 — 66%
muck
66+
peat
PLASTICITY OF SOILS WITH
LESS THAN 20% CLAY
eon plastic gritty, cannot thread
slightly plastic rough to smooth,
hard to thread
plastic smooth to wary.
easy to thread
OF GRAVEL LABORATORY TESTS
a trots 0 — S% DO Dry Density, pef OC Organic Content. %
a little 6 — 1S% WD Net Density, gad S Percant of Saturation, %
some 16 — 30% MC Natwal Moisture Content, % SG Specific Gravity
and 31 — SO% LL Liquid Limit, % C Cohesion
PL Plastic Limit, % 0 Angle of Internal Friction
►l Plasticity Index, % qu Unconfined Compressive Strength
DRILLING NOTES: Standard penetration Not borings were advanced by 216" or 3%" I.D. hollow -stem augers unless noted other-
wise. Jetting water was toed to clean out sugar prior to sampling only when indicated on log. Standard
Penetration test brings we designated by the prefix -sr, (Split Tuba).
Power auger brie* owe advanood by 4" or 6" diameter, continuous flits, solid stem augers. Soil classification
and ovate depth are inferred from disturbed Nmplas supred to the surface and we therefore somewhat
approximeta. ►over sugar brings we designated by the prefix "B'
Hand probings ware advanced manually voth a 116" diameter probe and an limited to the depth from which
the probe can be manually withdrawn. Hand probings an indicated by the prefix "H'
CLASSIFICATION: Classification on kegs is made by inspection in accordance with the Unified Soils Classification System
(tee attached chart) using visual -manual procedures unless noted otherwise.
GROUND WATER: Observations were made at the tines indicated. ►rosity of soil strata, seasonal weather conditions, site
topography. etc., may cause changes in the water levels if led on the logs.
SAMPLING: All Nmpi are taken with the standard 2" O. D. solit•tube sampler, except where noted. TW indicates thin -
well undisturbed temple.
BPF: Numbs I idicaN blows per foot recorded in standard penetration salt, alto known as "N" value. The sampler
is Nt 6" Into undisturbed soil below the hollow -sum suer. Driving resistances an then counted for second
and third 6" incrienants and added to get OFF. Wisre they differ significantly, they we reported in the
follawing form — 2112 for the second and third 6" incre rernts reepeetively.
WH: WH wndicates that asmpler penetrated soil under weight of hemmer and rods alone, driving not required.
NOTE: Ail tan run in scawdence with applicable ASTM stsndwdo.
omen
ENGINEERING TESTING
1 CL'.SSIFICATION OF SOILS FOR ENGINEERING PURPOSES
ASTM DESIGNATION D-2487
1
Major Divisions
N
^
M �
V
4N Q
Qp
i ■ Z
,�
to Ox0
L
C
N N
w
it=
Ogg
r N
4 Lu -V
,5;a
aa$
e
u0
$A
i-
Group Typical
Symbols Names Classification Criteria
Hell -graded gravels and
Cu - 000 ID 14
Greater than 4
c
ow
gravel -sand mixtures,
little or no fines
(D a
Ca ' Dla
Between 1 and 3
N
3
Poorly graded gravels and
rap
ravel -sand mixtures,
Not meeting both criter's for OW
r
little or no fines
o
e
511 g9
siravels gravel- It mixturres
Atterbe limits plot
below " line or
Atterberg limits plot-
�•• c
GN
man
plasticity index
ting in hatched area
less than 4
are borderline
b•�• t
Clayey growls, gravel-
a „�limits P o
above A line and
irinclassifications re-
qug use of dual
r
OC
sand -clay mixtures
plasticity index
7
symbols
�•a•
greater than
Cu - D80/D10
Greater than 6
g
N
Aell-yrated sands and
SW
gravelly sends, little
or no fines
(D)E
Ca -
Been 1 and 3
QN$ e
N
Din X Dgp
6
ZG^
Poorly sands and
BP
graded
gravelly sands, little
Not nesting both criteria for BW
4
or no fines
N
GZM
Silty sands, sand -silt
Atterbary limits plot
below "A line or
Atterborg limits plot-
T
eL
W OIL
BN
mixtures
plasticity index less
ting in hatched area
than 4
-are borderline clas-
Clayey sands, sand -clay
erg plot
above A line and
sifications requiring
use of symbols
N 0
BC
mixtures
greater titann4ax
Inorganic silts, rock
flour, silty or clayey
AM fine sand
Inorganic clays of ow 5-
media plasticity, yrav-
lZ ally clays, sandy c�ays,
silty clays, lean clays
Organic silts and organic
OL silty clays of low
plasticity
Inorganic silts, micaceous
0 or diatomaceous silts,
elastic silts
Inorganic clays of high
M plasticity, fat clays
Organic clays of median
OH to high plasticity
60
s0
1 40
.r
30
20
a 14
Plaetietiy chart
For *low of fine-
Qrat"d #Ot 1e and fine Jleotton
of ooa ne-gmatned coils.
AtterbaV unite pplotting in
hatched area are borderitne
el"eifteattane requiriv
we of drei 40""to.*
/{gwtim 0f A-1
PI - 0. ?a Q_ 20Cz
,
0 0 10 20 30 40 50 60 70 80 90 100
Ltqui,d Uxdt
nl organic soils Pt Peat, uwck dnd other
H1
9 Y ►g highly organic soils Visual -manual identification
onAun'
ENGINEERING TESTING
11
Telephone 473.7357
CITY Of ORONO
Post Office Box 66 • Crystal Bay, Minnesota 55323 • Municipal OfScaa
On the North Shore o/ Lake Minnetonka
February 14, 1978
Mr. James Olson
A.onestroo, Rosene, Anderlik 6 Associates, Inc.
2335 Hwy 36
St. Paul, MN 55113
Dear Mr. Olson:
Enclosed is a cod., of the Braun Engineering Report on soil borings
and percolation tests for Lot 8, Block 1 of the Farview Addition.
Please note that of 21 percolation tests performed, only 3 gave
results of 60 mpi or less. Three possible systems have been
roposed, including an osmosis system with which I am not familiar.
riease review this report and recommend which system, if any, would
be feasible for this lot. Thanks!
Sincerely;
4'-
Michael P: Gaffron
Septic System Inspector
'LPG: sm
Enclosure
8 A' Rom. 444d4 & 4. ,, 9,wr
e�
"is */. 16"A -44FAMOV d6
one 0. •eweeb", P.R.
Lewrewer P. reYWw• ra.
At Aa4 NAmoswls aa»a
Robot Romm,dM0
reek, r.a.
ph C.
Jeeerk c. An4dtk, r.t
P.R.Pir.Gig=X"A
A.
re�w �. r+,r,bA, Pi.
P�nssv `-t �,tA^
WOMwV
O
Buller/ A. L nsbos P.F. the •�r.r, P.R.
Reber D. PHONVI, Pi.
Rk �n, rl.
February 21, 1978 FED '2
Rk"erf X. rrrwer, P.E.
JMWS C. otMw, P.H.
Rubes d" rl.
Afwvk, c..', *Id. r,s.
6
.q0 P.R.
Ar~gk R. MN&W' r r.
Mr. Michael P. Gaffro �
A. zp kkwx
"'
�
�R`-
Septic System inspecto
L"MHES M.
Lee M. kky
kp
KWAM M. obew
City of Orono
Box 66
Crystal Bay, Mn. 55323
Re: Percolation Tests
Lot 8, Block 1
Farview Addition
Cur File No. 139
Lear M: , C 'iron:
We have =.viewed the Soil Borings and Percolation Tests Report dated February 13,
1978 prepa�.ed by Braun Engineering Testing for the above lot. Based on the
test resulca indicated in the report, a standard septic tank-drainfield system
cannot .e apl,, wed. The tesz results exceed the minimum requirements by such a
large de,yree gnat no further consideration should be given to the standard sys-
tem.
With respect to innovative systems, we quote from Section 4 of the proposed
"City of Orono On -Site Sewage Treatment System Design Manual" as follows:
"Application for innovative system installation variances shall include
all the data required for standard system application, plus any addition-
al data necessary to establish the acct�ptsbility of the proposal. Such
data would normally include case histor, I similar installations,
manufacturer's literature, independent results and engineering re-
ports."
The Braun report suggests that the mound system may be ieasible. However, no
detailed design features or layouts are presented. The proposed On -Site Design
Manual indicates that percolation rates should be faster than 60 minutes per inch
on the surface and faster than 120 minutes per inch in the sub -soil and/or sub-
stratuir for the mound system.
We recommend that the Owner of Lot 8, Block 1 be advised that based on percola-
tion rates submitted in the test data, the standard septic tank-drainfield sys-
tem cannot be installed and further if he wishes to pursue any alternate
innovative system, he must submit a detailed design layout in accordance with
Section 4 listed above. The City of Orono should not be placed in the position
of designing a system for the property owner, but rather should review a proposed
design prepared for and submitted by the Owner.
Page 1.
Mr. Michael P. Gaffron
City of Orono
Crystal Bay, Mn. 55323
Re: Percolation Tests
Our File No. 139
February 21, 1978
If tie may be of further as tace in this matter, please contact us at your con-
venie� ,e.
Y_aY., very truly,
BONEST"G, ROSUNE, ANDERJIK & ASSOCIATES, INC..
J, C. Ols
CO.li
Page 2.
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E-4
Y -4" STRAW OR MARSH HAY L SANDY LOAM SOIL
GRASS COVER---,-- I V4" PERFORATED
SAND FILL
PIPE
6" TOPSOIL
MAXIMUM SLOPE
3 TO 1
OP % SLOPE
SU PLOWED OR
DISKED SURFACE 3/4' - 2 1/2" CLEAN ROCK
CROSS SECTION A - A
1 1/2"- 2" PIPE FROM
PUMPING CHAMBER
FTTTA\-TT-11
I V4"
PERFORATED
PIPE
BED AREA
*4 "- 2 1/2"
- CLEAN ROCK
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DIKEIN 1. 10' MAX DIKE
—TOTAL WIDTH
PLAN VIEW
SEWAGE TREATMENT MOUND WITH PRESSURE
DISTRIBUTION OF EFFLUENT
Telephone 473-7357
CITY of ORONO
Pat Once Box 66 • Crystal Bay, Minnesota SM23 • Municipal Office*
On the North Shore of Lake Minnetonka
February 27, 1978
Mr. Jim Olson
Bonestroo, Rosene, Anderlik & Associates, Inc.
2335 Highway 36
St. Paul, MN 55113
Dear Jim:
Mr. Scott Abernathy, of David Nitz, Inc., has or will soon
deliver to you plans for a proposed drainfield for Lot 8,
Block 1, Farview Addition, incorporating a Mound treatment
system. I believe you already have the Braun Engineering
report including perc tests for this lot.
Please review these plans and make a recommendation as to
approval or denial of this system. Thank you.
Sincerely,
Michael P. Gaffron
Septic System Inspector
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