HomeMy WebLinkAboutExcavating & Filling PermitCITY OF PRIOR LAKE
APPLICATION FOR
EXCAVATING/FILLING PERMIT
Permit No. -~r~ q~.~_/~ Date
447-4230
Applicant
Address:
~o~ Owner: ~
Address:
contac :
Address:
Consultant Engineer/Surveyor
Address:~/~ ~ ;_-" /[aGTO
Location of Property: //9/~' [~ t/
Legal Description: /.- o ~- ~, ct - t O ~ o O ~
Will the excavation or filling be in a: Watercourse
Purpose for the proposed excavating or filling:
Phone
Phone
Phone
Wetland Upland
Co.~ S -].-- o c i / o.,~ o/'c
Estimated start date: ~ - ~ o., 0 c/ Completion date:
What is the type of material to be removed or deposited: C I~-~
In what manner will the material be removed and/or deposited?
What highway, street, or other pubhc way w~ll material for removal or depositatton be hauled or carried. I
What, if any, street, avenue, lane, alley, highway, right of way, thoroughfare or public ground will be obstructed?
IT SHALL. nE THE RESPONSIBILITY AND THE BURDEN OF THE APPLICANT TO DEMONSTRATE TO THE SATISFACTION OF THE crrY
lNG CALCULATIONS OF A REOlSTERED PROFESSIONAL ENGINEER.
Will proposed excavation or depositon affect the City of Prior Lake overall storm water management plan? Yes No '~' If
yes, show proposed effect.
SUBMISSION REQUIREMENTS:
(A) Completed application form (B) Completed legal description (C) Map or plat of the proposed filling or excavating showing location and amount of material
proposed to be removed of deposited, with a description of the area (D) The depth or heights to which such removal or deposition is propo~ throughout the
area and the proposed angle of all slopes to he shown on a 2' contour map at a scale of 1" =50' or larger: The proposed and origifial contours shall be shown in-
cluding all properW within 150' of proposed excavation or deposition and shall be signed by an engineer or surveyor registered in the State of Minnesota .(Ii)
Erosion control plan (F) Affect on existing utilities (G) Protection of site by erection of suitable fence, guard or barricade (H) Application fee (I) Bond, let~r of
credit, or deposit of monies in a sum sufficiem to pay the cost of restoring a site. The extra ordinary costs of repairing, highways, streets or other poblic ways
along designated routes of travel and to pay such expenses aa the City may incur by reason of doing anything required to be done (J) Public linbilit~ insurance.
Amount of bond
Permit fee d,-~g.
Permit deposit
Letter of credit,
Signature of applicant
City Engineer
°r(~;)s~ ° f TTY,......M.,~ ~ ~ty insurance provided
'Y'-~~-} ,~" ~ ~ --- Date
_ .~~'.~/'~-- Date
Permit is valid if signed by City Engineer.
~8 -~T~ OON~O
LTANTS
STS DONSULTANTS~ LTD.
Single Family Dwelling at
14484 Waters Edge Trail
in Prior Lake, Minnesota
Tim & Vicki Klasell
Apple Valley, Minnesota
STS Project 9955Q
THE INFRASTRUCTURE IMPERATIVE
~ -~TS 00NSULTANTc~
STS Consultants, Ltd.
10900 - 73rd Ave. N., Suite 150
Maple Grove, MN 55369-5547
763-315-6300 Phone
763-315-1836 Fax
June 29,2004
Tim & Vicki Klasell
1066 Lowell Drive
Apple Valley, MN 55124
Re;
Subsurface Exploration and Geotechnical Engineering Report for a
Single Family Dwelling at 14484 Waters Edge Trail in Prior Lake, Minnesota;
STS Project 99550
Dear Mr. & Mrs. Klasell:
We have performed a subsurface exploration and geotechnical engineering analysis for
the proposed house at this lot. The attached report contains the logs of four soil borings,
an evaluation of the conditions encountered in the borings, and our recommendations for
site preparation, suitable foundation type, allowable soil bearing pressure for footing
design, and other geotechnical related design and construction considerations.
We appreciate the opportunity to work with you on your house project. If you have any
questions about our recommendations, please call us at 763/315-6300. To arrange for
our testing services during the earthwork and footing installation phase of this project,
please call Mr. Steve Ruesink, P.E. at the same phone number.
Sincerely,
STS CONSULTANTS. LTD.
Senior Project'Engineer
Principal Engineer/Vice President
MM/
Encs.
J HEREBY CERTIFY THAT I AM A PROFESSIONAL ENGINEER REGISTERED
UNDER THE LAWS OF THE STATE OF MINNESOTA, AND THAT THIS REPORT
Sig.e. Registration No.8435
MeYvyn I~indes~, P.E. Date J~)l'~' ~.
THE INFRAC~TRUCTURE IMPERATIVE
R699550-1 .doc
~STS P- FIN ~:~U LTANT5
Table of Contents
1.0 PROJECT OVERVIEW ............................... : ............................... 1
1.1 Project Description ................................................................ 1
1.2 Project Scope and Purpose .................................................. 1
2.0 EXPLORATION AND TESTING PROCEDURES .............. ; ........ 2
2.1 Boring Layout and Soil Sampling Procedures ...................... 2
2.2 Groundwater Measurements and Borehole Abandonment .. 3
2.3 Laboratory Testing Procedures .............................................3
2.4 Boring Log Procedures and Qualifications ........................... 3
3.0 EXPLORATION RESULTS ......................................................... 4
3.1 Site and Geology ................................................................... 4
3.2 Soil Conditions ...................................................................... 4
3.3 Groundwater Conditions ....................................................... 5
4.0 ANALYSIS AND RECOMMENDATIONS ................................... 6
4.1 Discussion ............................................................................. 6
4.2 Site Preparation for Building ................................................. 6
4.3 Foundation Recommendations ............................................. 7
4.4 Ground Supported Floor Slabs ............................................. 7
4.5 Foundation Backfill ................................................................ 8
4.6 Lowest Floor Elevation of House .......................................... 8
4.7 Exterior Pavement Areas ...................................................... 8
4.8 Construction Considerations .................................................. 9
4.9 Winter Construction ............................................................... 9
4.10 Construction Safety ............................................................. 9
4.11 Field Observation and Testing ............................................9
4.12 General Qualifications ....................................................... 10
5.0 STANDARD OF CARE ............................................................. 11
THE INFRABTRiiI:::TUR£ IMPEI~ATIVE
R699550-1.doc
~i~ ~TSi ~ ONSULTANT5
Tim & Vicki klasell
STS Project 99550
June 29, 2004
1.0 PROJECT OVERVIEW
1.1 Project Description
You propose to construct a one to two story slab-on-grade house on a lot at the east
margin of Lower Prior Lake. The house will probably have relatively shallow footings,
masonry bearing walls to grade or first floor level, with wood frame construction above.
We estimate that structural loads on the bearing wall footings will be in the range of 1.2 to
2.2 kips per lineal foot, with interior column loads of 35 to ¢5 kips.
1.2 Project Scope and Purpose
Our services were performed in accordance with the project scope outlined in our
proposal dated June 2, 2004. This work was authorized by Vicki Klasell on June 7, 2004.
The purposes of this exploration are to:
· Perform a subsurface exploration and testing program consisting of four soil borings
to 20 to 25 foot depth.
· Describe the soil and groundwater conditions encountered in our exploration.
· Characterize the subsurface conditions with respect to the site geology and the
proposed construction.
· Analyze the available subsurface information which is applicable to this project.
· Present recommendations for design of foundations and floor slab.
· Discuss the construction considerations related to earthwork and foundations.
THE INFI:~AI~TI~U~?TUII~Ir IMPEIg;ATIVE
R699550-1.doc
[~'~ E iT 5 [~ Q N-q U LTANT5
Tim & Vicki Klasell
STS Project 99550
June 29, 2004
2.0 EXPLORATION AND TESTING PROCEDURES
2.1 Boring Layout and Soil Sampling Procedures
STS recommended the number of soil borings, the'boring locations and depths. The
building corners had been staked by a land surveyor prior to our arrival on-site. An STS
engineer staked the STS boring Ioca:tions. The approximate boring locations in relation
to the outline of the proposed house are shown on the Soil Boring Location Diagram in
the Appendix. Our drill crew determined the ground surface elevations at the borings
with reference ~o the water ~eve~ in Prior Lake. We assumed tha~ the ~ake ~evel on June
27, 2004 was 902:8 feet National Geodetic Vertical Datum. The actual water elevation
on that date may have varied slightly from this figure. The actual measured water
elevation of Prior Lake on June 2, 2004 was 902.78 feet.
We drilled the borings on June 21, 2004 with a truck-mounted Diedrich D-50 drill rig
operated by a two person crew. The drill crew advanced the borings using continuous
flight hollow stem augers. Detailed descriptions of typical drilling procedures are included
in the Appendix. 'Drilling methods, depths, casing usage, drill rig type, foreman, and other
drilling information are indicated on the boring logs.
The drill crew sampled the soil in advance of the auger tip at 2.5 foot intervals of depth to
10 feet and at 5 foot intervals thereafter. The soil samples were obtained using a split-
barrel sampler which was driven into the ground during standard penetration tests in
accordance with ASTM D-1586, Standard Method of Penetration Test and Split-Barrel
Sampling of Soils. An explanation of typical STS drilling and sampling procedures is
presented in STS Field and Laboratory Procedures in the Appendix.
Recovered soil samples were described on field logs, containerized, and transported to
our laboratory for further examination and testing. The field logs also document sample
intervals, test data, observations of drilling resistance, groundwater occurrence and other
pertinent conditions.
THE INFRABTRUCTURE IMPERATIVE
R699550-1 .doc
~] ~T~i E:ONSULTANT5
Tim & Vicki Klasell
STS Project 99550
June 29, 2004
2.2 Groundwater Measurements and Borehole Abandonment
The drill crew observed the borings for free groundwater while drilling and after
completion. These observations and measurements are noted on the lower left corner of
the boring logs. The crew then backfilled the 25 foot borings with high solids bentonite
grout, and the 20 foot boring with soil cuttings, in compliance with Minnesota Department
of Health regulations.
2.3 Laboratory Testing Procedures
The penetration test split;spoon 'samples were visually examined by a geotechnical
engineer to estimate the distribution of grain sizes, plasticity, consistency, moisture
condition, color, presence of lenses and Ceams, and apparent geologic origin. The
engineer classified the soils according to type using the STS Classification System, which
is closely based on the Unified Soil Classification System. A chart describing the STS
Classification System is included in the Appendix. An explanation of typical laboratory
procedures is presented, in the Appendix.
2.4 Boring Log Procedures and Qualifications
The results of the field and laboratory observations and tests are printed on final boring
logs included, in the Appendix. Similar soils were grouped into the strata shown on the
boring logs, and the appropriate estimated USCS classification symbols were also added.
Note that the stratification depth lines between soil types on the logs are estimated based
on the available data. In-situ, the transition between soil types may be distinct or gradual
in either the horizontal or vertical directions. The soil conditions have been established at
our specific test hole locations only. Variations in the soil stratigraphy may occur
between and around the bo'rings, the nature and extent of which would not become
evident until exposed by construction excavation. These variations must be properly
assessed when utilizing the information presented on the boring logs. Additional
comments on boring log preparation and qualifications are contained in an Appendix
sheet entitled STS Standard Boring Log Procedures.
THE INfR.A~ITRUI:TLJRIr IMPERATIVE:
R699550-1.doc
~'~I~ ,..~ T ~] 0 ON 5 U L-TANT5
Tim & Vicki Klasell
STS Project 99550
June 29, 2004
3.0 EXPLORATION RESULTS
3.1 Site and Geology
The lot has been graded and is relatively level. A former house on the property has been
removed or razed.
Naturally occurring soils at this site consist of Iow plasticity sandy clay related to the Des
Moines ice lobe of the Wisconsin glaciation, water modified clayey till and clayey sand,
overlain by valley train sands of varying gradation.
3.2 Soil Conditions
We found from 0.3 to 0.7 feet of topsoil at borings 2 and 3, at the northeasterly end of the
proposed house. At boring 4, in the southeast corner, the topsoil had apparently been
removed by excavation. At boring 1, within the northwesterly portion of the south half of
the house pad, we found 7-1/2 feet of soft to firm sandy clay, which may be fill, or soil that
has been disturbed by excavation. The sandy clay layer, which extends to 7-1/2 foot
depth from present grade, is weak and potentially compressible, and is unsuitable for
foundation support.
Below the topsoil, or the suspected fill at boring 1, we found about a 15 foot thick stratum
of valley train sands including silty sand, fine to medium sand, and clayey sand with
traces of gravel. Standard penetration N-values in the sand formation ranged from 3 to
41. The uppermost portion of the sand layer is loose, and the lower portion is medium
dense to dense. If adequately compacted, the sand would be suitable for foundation
support.
A major stratum of lean sandy clay commences at depths of 15 to 22-1/2 feet below
ground surface, and extends beyond the termination depths of the borings. Standard
penetration N-values in this underlying sandy clay range from 15 to 36, representative of
a very stiff to hard consistency. This soil has adequate load bearing capacity and Iow
compressibility, and is a suitable foundation subsoil.
THE INF'RABTRUCTURE IMPERATIVE
R699550-1 .doc
~ -~TS [-:- o N S IJ LTANT8
Tim & Vicki Klasell
STS Project 99550
June 29, 2004
There are also random seams or lenses of lean sandy clay within the overlying sand
formation. These inclusions are typical when a clay fill has been water modified and then
becomes covered with fluvially deposited, valley train sand.
3.3 Groundwater Conditions
We observed free groundwater in all four borings, at final measured depths of 2.7 to 3.8
feet below ground surface, corresponding to elevations 901.1 to 902.0 feet. Had our
period of observation been longer, the groundwater level would probably have risen to
match the lake water elevation.
This site is directly adjacent to the north end of Prior Lake, known as Lower Prior Lake.
Prior Lake was formerly a landlocked lake with no outlet. In the early 1980's, the lake
elevation rose to an unacceptable level, and an outlet was built in 1983. We were
informed by the Director of the Prior Lake-Spring Lake Watershed District that the water
elevation in Prior Lake during the spring of 2001 was 904.3 feet. The ordinary high water
level of the lake is 904.0 feet. On June 2, 2004, the water elevation in the lake was
902.78 feet.
The groundwater elevation at this site is directly related to the prevailing water level in
Prior Lake, and will fluctuate seasonally and annually, as the lake level varies.
THE INFI:{AI~TF~UCTURi~ IMPERATIVE
R699550-1.doc
Tim & Vicki Klasell
STS Project 99550
June 29, 2004
ST~ P- n N SI ILTANTS
4.0 ANALYSIS AND RECOMMENDATIONS
4.1 Discussion
Some soil correction will be required to prepare the building pad for house construction.
We found soft and potentially compressible clayey soils that extend to 7-1/2 foot depth at
boring 1 and 5 foot depth at boring 3. These soils should be excavated and replaced with
compacted sand fill.
After soil correction, the house may be supported on conventional spread footing
foundations bearing on medium dense naturally occurring clayey or silty sand, or on
compacted sand fill.
The on-site clayey and silty sand is suitable as a pavement subgrade. However in areas
where the subgrade soil is a sandy clay, this should be subcut approximately 18 inches
and replaced with sand fill.
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4.2 Site Preparation for Building
An excavation should be commenced at the location of boring 1, to remove the soft to
firm sandy clay. The lateral extent of this clay pocket can be determined in the field, by
careful observation of the exc$/ated soil. A similar excavation should commence at the
location of boring 3, at the northeasterly corner of the house pad, to remove a buried
layer of soft sandy clay. The excavations should extend at least 5 feet laterally outside
the building lines. Since these excavations will extend below the lake water level,
groundwater intrusion will be encountered. This should be controlled by pumping from
sump pits in the deepest portion of the excavation. Even if total dewatering cannot be
achieved, the pumping should be sufficient to depress the water level by several feet.
The fill used to replace the soil from the excavations should be an imported fine to coarse
sand with some gravel, and not more than 5% passing the No. 200 sieve. The first lift of
this fill into the excavations can be 2 feet thick before compaction is attempted. The sand
fill should be compacted with a smooth drum vibratory roller, to at least 100% of the
THE INFR.ASTRLICTIJR£ IMFEI:IATIv£
R899550-l.doc
Tim & Vicki Klasell
STS Project 99550
June 29, 2004
E~ StSi
~; DNSULTANT~
Standard Proctor dry density, ASTM D-698. Sand fill above the first lift should be spread
in 8 to 10 inch lifts, and should be similarly compacted. In the portions of the house pad
outside of the two subcut areas, the exposed subgrade after topsoil stripping should be
surface rolled and compacted prior to placement of additional fill.
Procedures to reduce subgrade deterioration and for subgrade improvement when locally
unsuitable soils are encountered are discussed in sheets entitled STS Subgrade
Stabilization Guideline and STS Subgrade Protection Guideline in the Appendix.
4.3 Foundation Recommendations
The house and garage may be supported on conventional spread footing foundations
bearing on compacted sand fill, or on medium dense naturally occurring clayey and silty
sand. Perimeter house footings should be based at a minimum depth of 3 feet 8 inches
(3.67 feet) below outside finished grade for frost protection, and should be at least 22
inches wide. Interior column footings, if any, should be based at least 16 inches below
the top of the floor slab, and should be at least 3 feet wide. Interior continuous bearing
wall footings should be based at least 16 inches below the top of the floor slab, and
should be at least 16 inches wide.
The footings may be designed for a net allowable soil bearing pressure not to exceed
2000 pounds per square foot. This recommended soil bearing pressure provides a
theoretical factor of safety against shear or bearing capacity failure in excess of 3. Total
and differential settlements corresponding to this loading should be less than 1 inch and
1/2 inch, respectively, provided the bearing soils are not frozen or disturbed at the time of
footing installation.
4.4 Ground Supported Floor Slabs
The recommended building pad preparation will provide appropriate support for the
house and garage floor slabs. If portions of the house floor slab are to be surfaced with
wood flooring, we recommend that a vapor barrier should be installed below those
portions of the slab. If a vapor barrier is used, it should be installed in accordance with
THE INFR.AaTRUI~TURE IMPE:~TIVE:
R699550-1.doc
E~ ~t~i P. n N ~ULTANT~
Tim & Vicki Klasell
STS Project 99550
June 29, 2004
the recommendations given in the ACI Manual of Concrete Practice, Part 2, Section
302.2.4.1.
4.5 Foundation Backfill
The footings should be backfilled with the same imported fine to coarse sand used within
the house pad. Within 3 feet of the foundation walls, the backfill should be compacted
with manually operated vibrating plate or sled type compactors. The backfill should
achieve a density of at least 98% of the maximum Standard Proctor dry density. The use
of large mechanical equipment close to the foundation walls could potentially damage
them.
4.6 Lowest Floor Elevation of House
We recommend that the lowest floor elevation of the house should be at least 2 feet
above the ordinary high water level of Prior Lake, or higher if required by the local
building ordinance.
4.7 Exterior Pavement Areas
Obviously organic topsoil should be stripped and removed from patio slab; sidewalk, and
driveway areas. The exposed subgrade should be thoroughly rolled and surface
compacted to at least 100% of the maximum Standard Proctor dry density. If clay soils
are encountered at subgrade level, they should be subcut 18 inches and replaced with
the same type of sand fill used for the house pad.
The recommended pavement thickness design for the driveway is:
Material
Hot-mix bituminous wearing course
Hot-mix bituminous binder course
Aggregate base course, MnDOT Class 5
100% crushed rock or recycled concrete
Thickness - inches
1.5
1.5
THE: INFI:~A~TI~UCTLIRE IMPEI~ATIVE:
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~ST~ I-:- o N S U LTANTS
Tim & Vicki Klasell
STS Project 99550
June 29, 2004
4.8 Construction Considerations
The excavation for the soil correction will extend below lake water level and is likely to
encounter groundwater intrusion. A sump pit should be dug at the deepest part of the
excavation, and sufficient pumping should be done to temporarily depress the water level
by several feet. This will permit proper placement and compaction of the imported sand
fill. Under no circumstances should foundation concrete be placed into standing water.
Trenches for underground utility lines serving the house may alSo encounter some
groundwater intrusion, in which case dewatering would also be required.
4.9 Winter COnstruction
Only unfrozen fill should be used. Placement of fill and/or' foundation concrete must not
be permitted on frozen soil, and the bearing soils under footings or under the floor slab
should not be allowed to freeze after concrete is placed, because excessive post-
construction settlement could occur as the frozen soils thaw.
4.10 Construction Safety
All excavations must comply with the requirements of OSHA 29 CFR, Part 1926, Subpart
P "Excavations and Trenches". This document states that excavation safety is the
responsibility of the contractor. Reference to this OSHA requirement should be included
in the job specifications.
The responsibility to provide safe working conditions on this site, for earthwork, building
construction, or any associated operations is solely that of the contractor. This
responsibility is not borne in any manner by STS Consultants, Ltd.
4.11 Field Observation and Testing
We recommend that the earthwork and footing installations for this house be observed
and tested by a qualified engineering technician working under the direction of a
THE INI:'RABTRUCTURE IMP~EATIVE:
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{~i~ S T _c::; r. o N 5 U LTANT5
Tim & Vicki Klasell
STS Project 99550
June 29, 2004
geotechnical engineer, to determine if the soil and groundwater conditions encountered
are consistent with those anticipated based on our exploration. Foundation subgrades
should be tested to check for adequate bearing conditions. Subgrades for slabs,
pavement and new structural fill should be tested and unsuitable areas improved. Fill
placement and compaction should be monitored and tested to determine that the
resulting fill conforms to specified density and strength requirements. Structural materials
such as foundation concrete should also be tested for conformance to specifications.
STS would be pleased to provide the necessary field observation, monitoring and testing
services during construction.
4.12 General Qualificatioas
This report has been prepared to aid in the evaluation of a single family dwelling at this
property, and to assist the architect and/or builder in the design and construction of this
project. The scope is limited to the specific house and location described herein, and our
description of the project represents our understanding of the significant aspects relevant
to soils and foundations. In the event that there are changes in the nature, design or
location of the building, the opinions and recommendations contained in this report shall
not be considered valid unless STS reviews these changes and modifies or verifies the
recommendations in writing.
THE INFFT. ABTRUCTURE IMPI:'R~TIVE
10
R699550-1 .doc
Tim & Vicki Klasell
STS Project 99550
June 29, 2004
5,0 STANDARD OF CARE
The recommendations and opinions contained in this report are based on our
professional judgment. The soil testing and geotechnical engineering services performed
for this project have been conducted in a manner consistent with that level of skill and
care ordinarily exercised by other members of the profession currently practicing in this
area under similar budgetary and time constraints. No other warranty, express or
implied, is made.
THE INFRAI=iTIg, UCTURE I~I~E'RATIVE
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~.. ri N S U LTANTS
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~ EiT~ 0 ON ~i LIITANTB
APPENDIX
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2.
3.
4.
5.
o
7.
8.
9,
THE INFRABT~UP-TURE IMPERATIVE
Boring Location Diagram
Boring Logs
STS General Notes
STS Soil Classification System
STS Field and Laboratory Procedures
Subsurface Exploration Field Procedures
Field Sampling Procedures
Laboratory Procedures
STS Standard Boring Log Procedures
STS Subgrade Protection Guideline
STS Subgrade Stabilization Guideline
STS Earthwork Guideline
R699550-1 .doc
SUR~,~'Y PRE]~ARE~ FOR:
}N:
~e west half of lot I~, Boudins Manor
~tt County,
ss:
tONUMENT FOUND
IONUW£NT SET ~O WARKFO
.ICON SE N0.101 ~3
LE-GE'ND
e'B-# BOFII~ LOCA TI(~
1 OWNER LOG OF BORING NUMBER
Tim & Vicki Klasell
PROJECT NAME ARCHITECT-ENGINEER
s'rs Cen$-Itants Ltd, Single Family Dwelling
SITE LOCATION ~ UNCONFINED COMPRESSIVE STRENGTH
14484 Waters Edge Trail, Prior Lake, MN ~"~ TONS/FT.'
1 2 3 4 5
~' UJ PLASTIC WATER LIQUID
~. o ~ ~ DESCRIPTION OF MATERIAL X- .... · .... .-~
~.~ ~ ~ ~ ~ ~..~ 10, 20, 30, 40, 50,
STANDARD
o: SURFACE ELEVATION +905.1 NGVD ~ ~
PENETRATION
BLOWS/FT
-~ 10 20 30 40 50
FILL: Sandy clay, random lenses of fine to medium sand, trace
1 SS gravel - gray - very soft to firm - (CL, lenses SP) ·
HS i5
2 SS
5.0 HS
3 ,SS
HS 7.5
Fine to coarse sand, little gravel - gray - saturated - loose to
4 SS medium dense - (SW)'
lO.O HS
:11
5 SS
\
\
HS
\
15.0 15.0 '.
Clayey fine to medium sand - brown - saturated - medium
6 SS dense to dense-(SC) ~!9
'\
HS \
20.0
40
7 SS
: I lC ~2.5 ,.'
Sandy clay, trace gravel - red-brown - very stiff - (CL) ·
8 ss .0
25.0 25.0
· Cai brated Penetr ~meter
End of boring at 25.0 ft.
Boring backfilled with high solids bentonite grout.
The stratification lines represent the approximate boundary lines between soil types: in situ, the transition may be gradual.
WL BORING STARTED ! STS OFFICE'"' P ,,""'nnea-o"s
Area
06
4 ft. WS 6121/04
WL BORING COMPLETED ENTERED BY SHEET NO. OF
3.7 ft. ACR 6/21/04 DN 1 1
WL i RIG/FOREMAN APP'D BY STS JOB NO.
Diedrich D-50/TM MM 99550
Tim & Vicki Klasell
'~ROJECT NAME ARCHITECT-ENGINEER
S'I'S Consultan~ Ltd. Single Family Dwelling
SITE LOCATION ~ UNCONFINED COMPRESSIVE STRENGTH
14484 Waters Edge Trail, Prior Lake, MN
1 2 3 4 5
~ o~ PLASTIC WATER LIQUID
LIMIT % CONTENT % LIMIT %
~ ~ ~ ~ DESCRIPTION OF MATERIAL
-
~ ~ ~ ~ 10 20 30 40 50
~ ~ ~ ~> ~" , ....
¢3 ~u o. n ~ O Q ~ STANDARD
~ ~ SURFACE ELEVATION +904.3 NGVD ~ ~ (~ PENETRATION BLOWS/FT.
10 20 30 40 50
0.7 Organic sandy siR, trace fine roots - brown-black - moist - (OL)
.. 1 SS Silty ~ine to medium sand, trace grave~ - brown, we~ to
saturated - loose - (SM)
HS
4.7. :
5.0 HS Silty and clayey sand, trace gravel, lenses sandy clay - gray -
loose- (SM-SC, lenses CL)
3 ss
7.3 ",,
· '~ Silty fine to medium sand - gray - saturated - medium dense -
4 SS (SM) '.~4
10.0 NS ~.8 ./
Fine to coarse sand, little gravel - gray - saturated - loose. /
5 SS! (SW)
HS
15.0 ~5.o '. I
,
Sandy clay, lenses clayey sand, little gravel - gray - stiff - (CL, 5
6 SS lenses SC)
~8.o
HS Clayey sand, little to some gravel - brown to red-brown - I
saturated - medium dense to dense - (SC)
20.0
7 SS J
I
i ',
HS I \
\
~ ss
25.0 25.0
End of boring at 25.0 ft.
Boring backfilled with high solids bentonite grout.
The stratification lines represent the approximate boundary lines between soil types: in situ, the transition may be gradual.
I
I wL BOR[NO STARTED S TS OFFICE
3.5 ft. WS 6121104 Minneapolis Ama - 06
i wL BORING COMPLETED ENTERED BY I SHEET NO. OF
2.7 ft. ACR 6/21/04 DN 1 1
WL RIG/FOREMAN APP'D BY STS JOB NO
Dledrlch D-5OITM MM 99550
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._1 OWNER LOG OF BORING NUMBER 3
Tim & Vicki Klasell
PROJECT NAME ARCHITECT-ENGINEER
STSConsultantsL,td. Single Family Dwelling
SITE LOCATION .,.,'%. UNCONFINED COMPRESSIVE STRENGTH
14484 Waters Edge Trail, Prior Lake, MN ~"~ TONS/FT~
1 2 3 4 5
~" "' PLASTIC WATER LIQUID
~ ~ LIMIT % CONTENT % LIMIT %
- ~ ~- DESCRIPTION OF MATERIAL X- .... ·
-- ~ >.. 10 20 30 40 50
>q
~ ~,' SURFACE ELEVATION +904.8 NGVD
..L3.3 Or anic sand silt-black- OL
I SS Silty fine to medium sand - brown - moist to wet~- loose - (SM)
HS ~.5
lensesSandy clay, lenses clayey sand, trace gravel - gray - soft - (CL,
2 SS SC)
5.0 HS 5.0
Silty fine to medium sand, trace gravel - brown - saturated -
3 SS very loose to medium dense - (SM)
\
HS
4 SS
I
10,0 HS :
5 SS
15.0
6 SS J ~6
\
\
HS '\
\
20.0 2Q,O '\
l Sandy clay and clayey sand, little gravel - gray-brown - very
0
7 SS stiff to dense - (CL-SC)
HS
8 SS
25.0 ~5.0
End of boring at 25.0 ft.
Boring backfilled with high solids bentonite grout.
The stratification lines represent the approximate boundary lines between soil types: in situ, the transition may be gradual.
WL BORING STARTED STS OFFICE"" ~' ,,""=nnea"o"s
Area
06
5 fi. WS 6121104
WL aORING COMPLETED ENTERED SY SHEET NO. OF
2.8 ff. ACR 6121104 DN 1 1
WL RIG/FOREMAN APP'D BY STS JOB NO,
Diedrlch D-50/TM MM 99550
1 OWNER LOG OF BORING NUMBER 4
Tim & Vicki Klasell
~ PROJECT NAME ARCHITECT-ENGINEER
ST$ Consultants Ltd. Single Family Dwelling
SITE LOCATION 4~. UNCONFINED COMPRESSIVE STRENGTH
14484 Waters Edge Trail, Prior Lake, MN %'~' TONS/FT,2
1 2 3 4 5
' - PLASTIC WATER LIQUID
ff ~ ~ LIMIT ~ CONTENT ~ LlUlT %
~ I~ DESCRIPTION OF MATERIAL
0 m ~ ~ ~ ~ STANDARO
~ ~ ~ ~ ~ SURFACE ELEVATION +904.9 NGVD ~ ~ ~ .ENETRATION BLOWS,FT.
Silty fine to coarse sand, little gravel - brown - moist - medium
1 SS dense- (SM)
Sandy cla~ and clayoy saad, trac~ ~rawl - ~rown - wet - stiff to
2 SS medium dense - (CL-SC)
/
Silty and clayey fine to medium sand, trace ~ravel - ~ray to
3 SS ~rown - saturated - w~ Ioo~ to medium d~n~ -
4 SS 2
5 SS
~5.0 ~5.0
Sandy clay, and clayey fine to coarse sand, little gravel - -
~ SS ~ray-~rown to ~rown - ~aturat~d - w~ stiff to modium dense - ~ '
(Ok-SC)
HSI ~
7 SS
20.0 Z0.0
End of boring at 20.0 ff.
Boring backfilled with cuttings.
lhe stratification lino~ represent th~ approximat~ bounda~ lino~ ~e~on ~oil ty~s: in situ, tho transition may ~o ~radual.
BORING STARTED STS OFFICE Minneapolis
WL 5 fi, WS 6121104
Area
06
WL BORING COMPLETED ENTERED BY SHEET NO. OF
3.8 fi, ACR 6121104 DN I 1
WL RIG/FOREMAN APP'O BY STS JOB NO.
Diedrich D-50~M MM 99550
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STS General Notes
_c:::: T ~ P. 0 N i:::: U LTA N T ~::
DRILLING & SAMPLING SYMBOLS:
SS: Split Spoon - 1-3/8" I.D. 2" O.D.
Unless otherwise noted
ST: Shelby Tube-2" O.D.
Unless otherwise noted
PA: Power Auger
DB: Diamond Bit-NX, BX, AX
AS: Auger Sample
JS: Jar Sample
VS: Vane Shear
Standard "N" Penetration:
OS : Osterberg Sampler
HS : Hollow Stem Auger
WS: Wash Sample
FT : Fish Tail
RB: Rock Bit
BS: Bulk Sample
PM: Pressuremeter Test
GS: Giddings Sampler
Blows per foot of a 140 pound hammer falling 30 inches on a 2
inch O.D. split spoon sampler, except where otherwise noted.
WATER LEVEL MEASUREMENT SYMBOLS:
WL : Water Level
WS : While Sampling
WD : While Drilling
AB : After Boring
WCI : Wet Cave In
DCI : Dry Caveln
BCR : Before Casing Removal
ACR .: After Casing Removal
Water levels indicated on the bo. ring logs are the levels measured in the boring at the time indicated. In
pervious soils, the indicated elevations are considered reliable groundwater levels. In impervious soils,
the accurate determination of groundwater elevations may not be possible, even after several days of
observations; additional evidence of groundwater elevations must be sought.
GRADATION DESCRIPTION AND TERMINOLOGY:
Coarse grained or granular soils have more than 50% of their dry weight retained on a #200 sieve; they
are described as boulders, cobbles, gravel or sand. Fine grained soils have less than 50% of their dry
weight retained on a #200 sieve; they are described as clay or clayey silt if they are cohesive and silt if
they are non-cohesive, in addition to gradation, granular soils are defined on the basis of their relative in-
place density and fine grained soils on the basis of their strength or consistency and'their plasticity.
Maior Component of
Sample
Boulders
Cobbles
Gravel
Sand
Silt
Clay
Size Ranqe
Over 8 in. (200 mm)
8 inches to 3 inches
(200 mm to 75 mm)
3 inches to #4 sieve
(75 mm to 4.76 mm)
#4 to #200 sieve
(4.76 mm to 0.074 mm)
Passing #200 sieve
(0.074 mm to 0.005 mm)
Smaller than 0.005 mm
Description of Other
Components
Present in Sample Percent Dry Wei.qht
Trace 1-9
Little . 10-19
Some 20-34
And 35-50
CONSISTENCY OF COHESIVE SOILS:
Unconfined Compressive
Strength, Qu, tsf
<0.25
0.25 - 0.49
0.50 - 0.99
1.00 - 1.99
2.00 - 3.99
4.00 - 8.00
>8.OO
Consistency
Very Soft
Soft
Medium (firm)
Stiff
Very Stiff
Hard
Very Hard
RELATIVE DENSITY OF GRANULAR SOILS:
N-Blows per foot Relative Density
0 - 3 Very Loose
4 - 9 Loose
10 - 29 Medium Dense
30 - 49 Dense
50 - 80 Very Dense
>80 Extremely Dense
(I)
STS Soil Classification System
D STS Consultants
Ua jar Group
Divisions Symbols Typicql Names Laboratory Classification Criteria
"~ Well-graded, gravel, ^ =. D~o .
~ ~ ~, ~o 6W orgravel-sandno fines mixtures, little E., t.u ~7.graa~.er than 4: Cc -
~ >e g ~ Poorly graded gravel, .~ E
~ ~ gravel-sand mixtures, Not meeting oll gradation requirements for GW
: ~ ~ o Sil~ gravel, gravel-sand- .-
c . ~ ~ GM silt mixtures ~ ~ ;~ Atterberg limits below 'A'
~ ~ line or PI less than ~ ~ove 'A' line with
~ PI between 4 and 7
-- ,~ '~ ~ E ~ ~ ~u ~ cases requiring use
~ e ~ ~ Clayey gravel, gravel-sand-i ~~ m~e Atterberg li~}[S above "A' of dual ~ymboJs
~'- ~ ~ GC - ~ ~ line or PI greater than 7
Well-graded sand. gravel, ~ O.
~grea~er than 6; Cc- etween 1
~: _ ~ ,-.
~ ~ = ~ Silty ,and. sand-silt ~, 8 A~e~,r~ limits b,low 'A" Limits platting in
z ~ ~ ~ ~ h~tched zone with PI
~ ~ c c c o between 4 ~nd 7
~ .~ -~ u .e o are b~
. [ · · o cases requiring use
= 'O ~ Clayey sand, sand-clay u e .~ ~ = ~ A~erberg limits above 'A' of dual symbols
='~ ~ ~ SC . ~ e llne or PI greeter than 7
~ m ~ mixtures
tnorgonlc silt end ve~ fine
send, rock flour, sil~ or Pl=sticity Ch=~ (2)
~ ML cl=yey fine Sand or clayey 60
~ si~t with slight plastici~ For classification of fine-grained
~ soils and fine fraction of /
~ Inorganic clay of Iow to coarse-grained soils.
medium pla~ticlty, gravel~ ~0
u ~ CL
~ ~ cl~. sandy clay, *il~ 'Atte~erg Umits plotting / I
~ clay. lean clay in hatched areas are CH or OH
= E borderline classifications //
~ = 40 requiring use of dual /
· - Organic silt and organic
~ OL ~ 'symbols. ~
~ ~ Equation of A-line:
P~-0.7~ (~-=0) / I
~ Inorganic silt, mlcaceous -- 30 ..... [ .... T .... : I ·
~ MH or diatomaceous fine sandy i ~
or silty soils, elastic silt ~ / MH or OH
~ ~ Inorganic cloy of high I / // ,
= 10 .....
~ Or~onic cloy of medium ~o / /
'7 II .,
~'~ ~ Peat and othsr highly 0 10 20 30 40 50 60 70 80 90 1C
~ ~'~ PT organic soil
~ ~" Liquid Limit (~)
For classification of fine-grained
soils and fine fraction of /
coarse-groined soils. //
Atterberg Limits plotting / ///
in hatched areas are CH or OH
border, ne classifications
requiring use of dual / //
'symbols. /
Equation of A-line: /
P1=0.73 (LL-20) //
..... r .... T,, .... ./: /'
~ ~ MH or OH
..... L .... /
I / eL or OL
!/
.__ tI /
,'-/ J orI aL .,
1) See 5TS General Notes for bomponent gradation terminology, consistency of cohesive soils and relative density of granular soils.
2) Reference: Unified Soil Classification System
3) Bordedine classifications, used for soils possessing characteristics of two groups, ore designated by combinations of group symbols.
For example: aW-aC, well-graded gravel-sand mixture with cloy binder,
STS Field and Laboratory Procedures ~iTc~ BON!SUL'rAN'I'IS
SUBSURFACE EXPLORATION FIELD PROCEDURES
Hand-Auqer Drilling (HA)
In this procedure, a sampling device is driven into the soil by repeated bl(:~ws of a sledge
hammer or a drop hammer. When the sampler is driven to the desired sample depth, the soil
sample is retrieved. The hole is then advanced by manually turning the hand auger until the
next sampling depth increment is reached. The hand auger drilling between sampling intervals
also helps to clean and enlarge the borehole in preparation for obtaining the next sample.
Power Auqer Drillinq (PA)
In this type of drilling procedure, continuous flight augers are used to advance the boreholes.
They are turned and hydraulically advanced by a truck, trailer or track-mounted unit as site
accessibility dictates. In auger drilling, casing and drilling mud are not required to maintain open
boreholes.
Hollow Stem Auqer Drillinq (HS)
In this drilling procedure, continuous flight augers having open stems are used to advance the
boreholes. The open stem allows the sampling tool to be used without removing the augers
from the borehole. Hollow stem augers thus provide support to the sides of the borehole during
the sampling operations.
RotarY Drillincl (RB)
In employing rotary drilling methods, various cutting bits are used to advance the boreholes. In
this process, surface casing and/or drilling fluids are used to maintain open boreholes.
Diamond Core Drillincl (DB)
Diamond core drilling is used to sample cemented formations. In this procedure, a double tube
(or triple tube) core barrel with a diamond bit cuts an annular space around a cylindrical prism of
the material sampled. The sample is retrieved by a catcher just above the bit. Samples
recovered by this procedure are placed in sturdy containers in sequential order.
THE INFEABTEIICTLIRE Ih4pERATIVE
STS Field and Laboratory Procedures
-'¢~ T -C~ I~. O N B MLTANTS
FIELD SAMPLING PROCEDURES
Au_cler Sam~olinq fAS)
In this procedure, soil samples are collected from cuttings off of the auger flights as they are
removed from the ground. Such samples provide a general indication of subsurface conditions;
however, they do 'not provide undisturbed samples,, nor do they provide samples from discrete
depths.
Split-Barrel Samplin.q (SS) - (ASTM Standard D-1586-99)
In the split-barrel sampling procedure, a 2-inch O.D. split barrel sampler is driven into the soil a
distance of 18 inches by means of a 140-pound hammer falling 30 inches. The value of the
Standard Penetration Resistance is obtained by counting the number of blows of the hammer
over the final 12 inches of driving. This value provides a qualitative indication of the in-place
relative density of cohesionless soils. The indication is qualitative only, however, since many
factors can significantly affect the Standard Penetration Resistance Value, and direct correlation
of results obtained by drill crews using different rigs, drilling procedures, and hammer-rod-spoon
assemblies should not be made. A portion of the recovered sample is placed in a sample jar
and returned to the laboratory for further analysis and testing.
Shelby Tube Samplin.cI Procedure (ST) - ASTM Standard D-1587-94
In the Shelby tube sampling procedure, a thin-walled steel seamless tube with a sharp cutting
edge is pushed hydraulically into the soil and a relatively undisturbed sample is obtained. This
procedure is generally employed in cohesive soils. The tubes are identified, sealed and
carefully handled in the field to avoid excessive disturbance and are returned to the laboratory
for extrusion and further analysis and testing.
Giddin.qs Sampler (GS)
This type of sampling device consists of 5-foot sections of thin-wall tubing which are capable of
retrieving continuous columns of soil in 5-foot maximum increments. Because of a continuous
slot in the sampling tubes, the sampler allows field determination of stratification boundaries and
containerization of soil samples from any sampling depth within the 5-foot interval.
THE INFRABTRUCTUFtE IMPERATIVE
STS Field and Laboratory Procedures
LABORATORYPROCEDURES
Water Content (Wc)
The water content of a soil is the ratio of the weight of water in a given soil mass to the weight of
the dry soil. Water content is generally expressed as a percentage.
Hand Penetrometer (Qp)
In the hand penetrometer test, the unconfined compressive strength of a soil is determined, to a
maximum value of 4.5 tons per square foot (tsf) or 7.0 tsf depending on the testing device
utilized, by measuring the resistance of the soil sample to penetration by a small, spring-
calibrated cylinder. The hand penetrometer test has been carefully correlated with unconfined
compressive strength tests, and thereby provides a useful and a relatively simple testing
procedure in which soil strength can be quickly and easily estimated.
Unconfined Compression Te~ts (Qu)
In the unconfined compression strength test, an undisturbed prism of soil is loaded axially until
failure or until 20% strain has been reached, whichever occurs first.
Dry Density (yd)
The dry density is a measure of the amount of solids in a unit volume of soil. Use of this value
~is often :made when measuring the degree of compaction of a soil.
Classification of Samples
In conjunction with the sample testing program, all soil samples are examined in our laboratory
and visually classified on the basis of their texture and plasticity in accordance with the STS Soil
Classification System which is described on a separate sheet. The soil descriptions on the
boring logs are derived from this system as well as the component gradation terminology,
consistency of cohesive soils and relative density of granular soils as described on a separate
sheet entitled "STS General Notes". The estimated group symbols included in parentheses
following the soil descriptions on the boring logs are in general conformance with the Unified
Soil Classification System (USCS) which serves as the basis of the STS Soil Classification
System.
THE. INFEABTI~UCTUEE llVlI=EEATIVE
STS Standard Boring Log Procedures
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STS STANDARD BORING LOG PROCEDURES
In the process of obtaining and testing samples and preparing this report, standard procedures
are followed regarding field logs, laboratory data sheets and samples.
Field logs are prepared during performance of the drilling and sampling operations and are
intended to essentially portray field occurrences, sampling locations and procedures.
Samples obtained in the field are frequently subjected to additional testing and reclassification in
the laboratory by experienced geotechnical engineers, and as such, differences between the
field logs and the final logs may exist. The engineer preparing the report reviews the field logs,
laboratory test data and classifications, and using judgment and experience in interpreting this
data, may make further changes. It is common practice in the geotechnical engineering
profession not to include field logs and laboratory data sheets in engineering reports, because
they do not represent the engineer's final opinions as to appropriate descriptions for conditions
encountered in the exploration and testing work. Results of laboratory tests are generally
shown on the boring logs or are described in the text of the report, as appropriate.
Samples taken in the field, some of which are later subjected to laboratory tests, are retained in
our laboratory for sixty days and are then discarded unless special disposition is requested by
our client. Samples retained over a long period of time, even in sealed jars, are subject to
moisture loss which changes the 'apparent strength of cohesive soil, generally increasing the
'strength from what was originally encountered in the field. Since they are then no longer
representative of the moisture conditions initially encountered; observers of these samples
should recognize this factor.
STS Subgrade Protection Guideline
Care should be exercised to minimize disturbance and degradation of subgrade
soils 'for foundations, slabs-on-grade, pavements and areas to be filled. Water
should not be allowed to pond on the surface of exposed subgrade soils, as this
could cause a softening of the subgrade, particularly when subjected to construction
traffic. Disturbed or softened subgrade soils should be removed to a suitable
undisturbed subgrade prior to fill or concrete placement.
Wet subgrade conditions may result from precipitation, runoff and groundwater
seepage through excavation walls and bottom. Precipitation risk can be minimized
by scheduling construction for drier seasons. The subgrade should be sloped to
drainage ditches and sumps .to minimize water accumulations. Runoff from adjacent
areas should be eliminated by use of berms and ditches to channel water away.
Groundwater seepage may be minimized by use of dewatering systems such as
wells and/or groundwater isolation systems such as cutoff walls or trenches.
Dewatering wells and/or groundwater isolation systems are recommended where
upward seepage is likely to cause the subgrade to loosen and become "quick" or
where lateral seepage may erode the face soil or cause "piping" of fines from the soil
matrix as exhibited by muddy or silt laden water.
If moisture or disturbance sensitive subgrade soils and wet conditions are expected
and construction of facilities bearing on the subgrade will not promptly protect the
subgrade soils, then consideration should be given to protecting the subgrade by
promptly placing appropriate combinations of a geotextile, a gravel base co.urse and
a lean concrete mud mat over the prepared and approved subgrade. Geotextiles
should be considered for use to separate the subgrade and gravel where subgrade
soils are at risk of migrating into the gravel base course. A suitably de:signed gravel
base course should help surcharge the subgrade and act as a drainage layer for
removing water accumulations. A lean concrete or flowable fill mud mat with a
thickness of several inches or more may be placed directly on the subgrade if
upward seepage does not exist. If base drainage is needed, a lean concrete or
flowable fill mud mat may be placed over a gravel base course. A mud mat will help
to isolate water, provide surcharge against loosening and will provide a stable
surface which is resistant to disturbance from construction traffic. Sump and pump
systems or dewatering wells should be used to remove any accumulating water or
water pressure in the gravel base course.
In any areas where unsuitable conditions develop despite protection measures,
subgrade stabilization should be performed as described in a separate sheet entitled
"STS Subgrade Stabilization Guideline".
STS Subgrade Stabilization Guideline
Subgrade stabilization may be required if zones of unsuitable soil are encountered
upon excavating to the subgrade level or if subgrade degradation occurs from
construction traffic, moisture accumulations, freeze-thaw cycles or other causes. Care
should always be used to minimize disturbance and degradation of subgrade soils
below foundations, slabs-on-grade, pavements and fill areas. Water should not be
allowed to pond on the surface of exposed subgrade soils, as this could cause a
softening of the subgrade, particularly when subjected to construction traffic.
Detrimental groundwater seepage should not be allowed to soften or loosen the
subgrade.
Unsuitable subgrade soils that are encountered or subgrade soils that become
disturbed or softened after exposure should be improved prior to concrete or new
material placement. The unsuitable soils should either be properly compacted in place
(if feasible based on material type, moisture content and thickness), or over-
excavations should extend through the unsuitable soils to remove them to an
underlying competent soil stratum.
If improvement by over-excavating is performed, footing walls can be extended deeper
and supported at the level where suitable soil is encountered. Alternatively, the over-
excavations can be backfilled to the design level using either a suitable compacted
structural fill material or a flowable cementitious fill.
If the over-excavations are backfilled using structural soil fill, the over-excavations
should extend a minimum of 1 foot horizontally from each edge of the footing for each
foot of fill required below the footing base. The structural soil fill should be placed,
compacted and tested in accordance with a separate document entitled STS
Earthwork Guideline. Generally, a well-graded granular material is more suitable for
stabilization work than cohesive soils. If an open-graded granular material is planned
as the backfill and the new subgrade or surrounding soils contain zones of
cohesionless fine sands or silts which may migrate into the open-graded backfill, then
an appropriately designed geotextile should be utilized to separate the stabilization
material from the subgrade and surrounding trench soils. Failure to provide such
separation may cause lost ground from surrounding soils and detrimental settlements.
Horizontal over-excavation is unnecessary if footing walls are extended to the iower
suitable subgrade level or if flowable fill is used to backfill the over-excavated area.
FIowable fill should have a sufficient Portland cement and/or fly ash content to achieve
28 day unconfined compressive strengths in the range of 50 to 200 pounds per square
inch (psi).
STS Earthwork Guideline
Fill or backfill required on the project should consist of a non-frozen, non-organic granular
material, aggregate or natural soil that is free of debris and particles larger than 25 percent of
the loose lift thickness. The natural water content of cohesive fill soil at the time of compaction
should generally be within -2 to +3 percent of the optimum water content as determined by the
Standard ProCtor test (ASTM D-698). Difficulty in obtaining the desired degree of compaction is
expected for soil that is too dry or too wet. The water content should be adjusted by sprinkling if
too dry or by scarifying and aerating if too wet. Blending with an additive such as fly ash or drier
soil may also help produce an acceptable water content.
Fill or backfill which is relatively uniform should be used on the project. Non-uniform materials
or mixing two or more materials will reduce the degree of certainty in the test results and will
tend to cause variable compressibility of the fill.
Fill or backfill should be placed on a firm, checked subgrade in horizontal lifts with a loose
thickness not greater than 12 inches for granular material and 9 inches for cohesive soil. It
should then be compacted with equipment that is suited to the soil type and compaction
requirements. Normally, vibratory roller or plate compactors are better suited for granular soils,
while a sheepsfoot or other "kneading" type of compactors are more effective in cohesive soils.
Lighter, hand-propelled compactors should generally be utilized to compact backfill within 5 feet
of structures unless the structure is designed to resist expected lateral pressures from use of
heavier compactors. When using lighter, hand-propelled compactors, a maximum loose lift
thickness of 8 inches should be used for granular material and 6 inches for cohesive soil.
Unless stated otherwise in the report text, fill or backfill that supports foundations, floor slabs
that..are loaded in excess of 400 psf, and roadway pavement that is subjected to concentrated
automobile or truck traffic should be compacted to a dry density of 95% or more of the
maximum dry density determined by Standard Proctor tests (ASTM D-698) on representative
samples of the fill material. Fill or backfill that supports lightly loaded floor slabs, sidewalks or
pavement that is subjected to dispersed automobile traffic should be compacted to a dry density
of 90% or more of the maximum dry density determined by Standard Proctor tests on
representative samples of the fill material. Compaction tests may be considered satisfactory if
the average of five consecutive tests on similarly compacted material exceeds the required
compaction and no individual test is more than 2% below the required percentage of
compaction.
Proper compaction is generally difficult to achieve near the edge of a slope or embankment fill
due to lack of confinement. For this reason, we recommend that the compacted fill or backfill
zone extend horizontally beyond the edge of foundations a minimum of 1 foot at the subgrade
level and then with depth at a minimum slope of 1 horizontal to 1 vertical.
Fill material acceptability, subgrade preparation and testing for suitability, fill placement and fill
compaction should be monitored continuously or at least regularly by a qualified soils technician
whom reports to the geotechnical engineer for the project. Compaction density for structural fill
should be tested at a minimum frequency of once per 5000 ft2 of fill area or once per 200 yd3 of
compacted material placed unless stated otherwise in our report. In non-structural fill areas,
testing frequencies may be reduced in half.