W911SA20B2007 Attachment 10 - Geotechnical Report Fort McCoy Twin Culvert Rehab.pdf

MINNESOTA IOWA WISCONSIN

Design Phase Geotechnical Evaluation:

Proposed Twin Culvert Replacement Bronze Court Fort McCoy, Wisconsin

Prepared for:

Mr. Jeremy Tomesh, PE SEH, Inc.

January 11, 2019

13648.18.WIL

Certification:

I hereby certify that this report was prepared by me or under my direct supervision, and that I am a duly Licensed Professional Engineer under the laws of the State of Wisconsin.

Devin M. Ehler, PE Geotechnical Engineer Registration Number 44630 Date: January 11, 2019

M I N N E S O T A I O W A W I S C O N S I N

Chosen Valley Testing, Inc.

Geotechnical Engineering and Testing • 1019 Second Ave. SW • Onalaska, WI 54650 • Telephone (608) 782-5505 • Fax (608) 785-2818

Mr. Jeremy Tomesh, PE January 11, 2019 Sr. Professional Engineer, Project Manager SEH, Inc.

312 South 3rd Street, La Crosse, WI 54601 jtomesh@sehinc.com

Re: Design Phase Geotechnical Report

Bronze Court

CVT Project Number: 13648.18.WIL

Dear Mr. Tomesh, As authorized, we have completed the geotechnical evaluation for the proposed twin culvert replacement on Bronze Court in Fort McCoy, Wisconsin. The attached report provides details of our analysis and recommendations. CVT appreciates the opportunity to provide geotechnical services on this project. If you have any questions about our report, please feel free to contact us at (608) 782-5505.

Sincerely, Chosen Valley Testing, Inc.

Devin M. Ehler, PE Geotechnical Engineer

TABLE OF CONTENTS

A. Introduction ______________________________________________________________ 2

A.1. Purpose _____________________________________________________________________ 2

A.2. Scope _______________________________________________________________________ 2

A.3. Boring Location and Elevation __________________________________________________ 2

A.4. Geologic Background _________________________________________________________ 2

B. Subsurface Data ___________________________________________________________ 3

B.1. Stratification _________________________________________________________________ 3

B.2. Penetration Test Results _______________________________________________________ 4

B.3. Groundwater Data ____________________________________________________________ 4

C. Project Design Data ________________________________________________________ 4

D. Culvert Recommendations ___________________________________________________ 5

D.1. Grading Recommendations ____________________________________________________ 5 D.1.a. Excavation ________________________________________________________________________ 5 D.1.b. Oversizing ________________________________________________________________________ 5 D.1.c. Filling and Compaction ______________________________________________________________ 5

D.2. Foundation Design ____________________________________________________________ 5 D.2.a. Bearing Capacity ___________________________________________________________________ 5 D.2.b. Settlement ________________________________________________________________________ 5

E. General Grading Recommendations ___________________________________________ 6

E.1. Earthwork ___________________________________________________________________ 6

E.2. Dewatering __________________________________________________________________ 6

E.3. Compaction __________________________________________________________________ 6

E.4. Cold Weather ________________________________________________________________ 7

E.5. Construction Testing and Documentation _________________________________________ 7

F. Level of Care ______________________________________________________________ 7

Appendix ____________________________________________________________________ 8

Boring Location Sketch

Log of Boring # 1 - 2

Legend to Soil Description

Fort McCoy Bronze Ct. Twin Culvert January 11, 2019 Project#: 13648.18.WIL Page - 2

Design Phase Geotechnical Evaluation Proposed Twin Culvert Replacement

Bronze Court

CVT Project Number: 13648.18.WIL

Date: January 11, 2019

A. Introduction

The intent of this report is to present our results to the client in the same logical sequence that led us to arrive at the opinions and recommendations expressed. Since our services must often be completed before the design, assumptions are sometimes needed to prepare a proper evaluation and to analyze the data. A complete and thorough review of this entire document, including the assumptions and the appendices, should be undertaken immediately upon receipt.

A.1. Purpose

This geotechnical evaluation was prepared to assist the design of the proposed twin culvert replacement on Bronze Court in Fort McCoy, Wisconsin. Our services were authorized by Mr. Randy Sanford, PE with SEH, on behalf of the Owner.

A.2. Scope

To obtain data for analysis, we were authorized to perform 2 penetration test borings. The borings were drilled to depths of about 20 to 25 feet. Our engineering scope consisted of providing geotechnical recommendations for support of a new culvert.

A.3. Boring Location and Elevation

The boring locations were indicated to Chosen Valley Testing by staking on site, provided by SEH. The approximate locations of the borings as-drilled are indicated on the Boring Location Sketch in the Appendix.

Ground surface elevations at the borings were estimated using a laser level. The centerline of the road in the middle of the existing culvert was used as a benchmark and was assigned an elevation of 100.0 feet.

A.4. Geologic Background

A geotechnical report is based on subsurface data collected for the specific structure or problem. Available geologic data from the region can help interpretation of the data and is briefly summarized in this section.

Geologic maps indicate that the uppermost soils in the area are primarily alluvial (water-deposited) sands and gravels. Bedrock is commonly within 50 feet of the surface and typically consists of Cambrian Age Sandstone.

Project#: 13648.18.WIL Page - 3

B. Subsurface Data

Methods: The borings were performed using penetration test procedures (Method of Test D1586 of the American Society for Testing and Materials). This procedure allows for the extraction of intact soil specimen from deep in the ground. With this method, a hollow-stem auger is drilled to the desired sampling depth. A 2-inch OD sampling tube is then screwed onto the end of a sampling rod, inserted through the hole in the auger's tip, and then driven into the soil with a 140-pound hammer dropped repeatedly from a height of 30 inches above the sampling rod. The sampler is driven 18 inches into the soil, unless the material is too hard.

The samples are generally taken at 2½, 5, and 10-foot intervals. The core of soil obtained is classified and logged by the driller and a representative portion is then sealed and delivered to the soils engineer for review.

B.1. Stratification

At the surface, the borings generally encountered about 14 to 16 inches of aggregate over approximately 6 inches of shaley aggregate. This was followed by sandy fill materials to depths of about 11 ½ feet.

Buried topsoil followed in the eastern boring (B-2) to approximately 13 feet.

Beneath the fill and buried topsoil, weathered sandstone was found in the western boring (B-1) to a termination depth around 19 ½ feet. While the eastern boring (B-2) came across natural clean sand to about 16 1/2 feet over weathered sandstone to a termination depth around 24 ½ feet below the surface.

The boring data has been summarized in the following cross section. For more detailed information, please refer to the individual Log of Boring sheets in the Appendix.

B-1 B-2

A p p ro xi m at e

E le va ti o n o n

D at u m

F ee t)

Boring Number

Aggregate

Fill

Buried Topsoil

Sand

Wx. Sandstone

Below Boring

West East

Project#: 13648.18.WIL Page - 4

B.2. Penetration Test Results

The number of blows needed for the hammer to advance the penetration test sampler is an indicator of soil characteristics. The number of blows to advance the sampler 1 foot is called the penetration resistance or “N”-value. The results tend to be more meaningful for natural mineral soils, than for fill soils. In fill soils, compaction tests are more meaningful.

Penetration resistance values (N-values) of 3 to 13 BPF (Blows per Foot) were recorded in the sandy fill material and buried topsoil, indicating they were variable.

The natural clean sand returned values of 12 to 30 BPF, indicating it was medium dense to dense. The weathered sandstone returned 50 hammer blows for ½ to 4 inches of sampler advancement, indicating it was very dense.

A key to the descriptors used to qualify the relative density of soil (such as soft, stiff, loose, and dense) can be found on the Legend to Soil Description in the Appendix.

B.3. Groundwater Data

During the drilling operation, the drillers may note the presence of moisture on the sampling instrument, in the cuttings, or within the borehole. These observations are recorded on the boring logs. The water level may vary with weather, time of year and other factors and the presence or absence of water during the drilling is subject to interpretation and is not always conclusive.

Water was observed in the borings around 14 ½ to 19 ½ feet below the surface during our exploration.

The depths correspond near elevations 80 ½ to 85 feet on the datum used to survey the borings. The water surface level in the stream was near elevation 82 ½ feet the day of our exploration. Groundwater levels are expected to fluctuate seasonally, similar to water levels in the stream, as well as with local weather patterns.

C. Project Design Data

Each structure has a different loading configuration and intensity, different grades, and different structural and performance tolerances. Therefore, the geotechnical exploration will be construed differently from one structure to another. If the initial structure should change design, we should be engaged to review these conditions with respect to the prevailing soil conditions. Without the opportunity to review any such changes, the recommendations may no longer be valid or appropriate.

The project is assumed to consist of the construction of a new cast-in-place twin box culvert. For purposes of our analysis, we assume a twin box culvert with two, 10-foot tall by 12-foot wide openings and 1-foot thick concrete floors/walls will be used. The bottom of the culvert is expected to bear about 14 feet below existing grades or near elevation 86 feet on the boring datum.

Project#: 13648.18.WIL Page - 5

D. Culvert Recommendations

D.1. Grading Recommendations

D.1.a. Excavation: Based on the boring data and the assumed bottom of culvert elevation, clean sand and weathered sandstone are expected to be present at bearing depth. These materials are judged to be suitable for support of the structure.

Any fill or buried topsoil materials that are found below the culvert bearing depth should be removed, along with any soft soils, debris, or otherwise deleterious materials that may be discovered during construction. Again, excavations are expected to extend through the unsuitable fill and buried topsoil materials according to the boring data.

D.1.b. Oversizing: Excavations below the culverts should be oversized at least 1-foot horizontally beyond the edge of foundations for each foot of fill needed below footing grade. This oversizing can be reduced by up to 50% if rather precise staking is present during grading.

D.1.c. Filling and Compaction: For ease of construction, we suggest using clean 1½-inch minus gravel as fill below the culverts. Aggregate base/dense graded base could also be considered for use as fill upon evaluation, but will require higher compactive effort and thinner lifts to attain proper compaction. The gravel or aggregate materials should be wrapped with a filter fabric – to prevent the migration of soils and scouring.

The above material recommendations are subject to specific material requirements from the manufacturer or the DNR. The below-culvert fill should be compacted to at least 95% of the soil’s standard Proctor density. Compaction testing of gravel and aggregate materials may not be feasible, in which case the materials should be tamped into place using “Ordinary” compaction until no yield is observed.

D.2. Foundation Design

D.2.a. Bearing Capacity: With assumed foundation loads and implementation of the earthwork recommendations, we are of the opinion that the natural clean sand and weathered sandstone are suitable for support of foundations sized to exert pressures of up to 4,000 pounds per square foot (psf). This allowable bearing capacity includes a safety factor of at least 3 against shear failure.

D.2.b. Settlement: Based on the recommended bearing capacity and assumed design information, total settlements are estimated to be on the order of 1 inch or less. Differential settlement across the culvert is estimated to be on the order of ½ inch or less.

D.2.c. Backfilling and Lateral Earth Pressures: Subject to specific earth pressure requirements by the manufacturer or regulatory agencies, we recommend using clean free draining sand having less than 10% particles passing a number 200 sieve as backfill behind culvert walls. The existing poorly-graded sand with silt fill may meet this criterion upon further evaluation.

Backfill should be brought uniformly along the side of the culvert and compacted to at least 95% of the

Project#: 13648.18.WIL Page - 6 soil’s maximum standard Proctor density or as otherwise specified. Clean sands have a rather high permeability. We suggest covering the surface of such materials with fabric and rip-rap or a thick layer of low permeable topsoil to limiting potential for erosion through the loss of material during times of high water due to seepage and “piping”.

The following table provides design parameters for the recommended clean sand backfill. These values do not include a safety factor.

The actual loads exerted on the structure will depend on the movement or flexure of the structure. For sand fill, horizontal movement or flexure of about 0.2% of the height of soil retained may be sufficient to mobilize frictional forces from the at-rest state to the active state.

E. General Grading Recommendations

E.1. Earthwork

Earthwork can likely be performed with a variety of equipment, provided sandy subgrades are not overly loose and dry. Standard vehicles with tires may have difficulty traversing the site under such conditions.

A backhoe is recommended for completing excavations.

E.2. Dewatering

The bottom of the excavation is expected to terminate in or near water-bearing sands. Because of the high permeability of the sands and water levels on site, diversion and/or dewatering wells will likely be required to keep excavations dry.

E.3. Compaction

All fill should be placed in lifts adjusted to the compactor being used and the material being compacted.

We recommend limiting lifts to no more than 1-foot – assuming large, self-propelled or tow-behind compactors are used. Thinner lifts should be used for lighter compaction equipment.

Poorly Graded Sand (SP) 95% standard Proctor density

Internal Friction Angle (degrees) 34

Cohesion (psf) 0

Coefficient of Friction between Concrete and Soil 0.50

Moist Unit Weight (pcf) 120

Backslope Behind Top of Wall (degrees) 0 (Flat)

At-Rest Coefficient (Ko) 0.44

Active Coefficient (Ka) 0.28

Passive Coefficient (Kp) 3.54

Project#: 13648.18.WIL Page - 7

E.4. Cold Weather

If the earthwork occurs during freezing temperatures, good winter construction practices should be used.

No frozen fill should be used nor should structural filling take place on frozen ground.

E.5. Construction Testing and Documentation

Excavating and grading should be evaluated and documented by qualified geotechnical personnel, after the unsuitable soils are removed and prior to the placement of any new fill or concrete. Fill should be evaluated for conformance to the project gradation recommendations and should be tested for compaction. If the filling proceeds during periods of freezing weather, full-time testing should be considered to help confirm that imported fill is thawed prior to and during compaction, and that all snow has been removed before placement of the fill.

Although our firm offers testing services relating to civil and structural components of the building (such as concrete testing, reinforcement observations, etc.) specification of such services is beyond our work scope and the designer should be consulted as to such requirements.

F. Level of Care

The services provided for this project have been conducted in a manner consistent with that level of care and skill ordinarily exercised by members of the profession currently practicing in this area, under similar budget and time constraints. This is our professional responsibility. No other warranty, expressed or implied, is made.

Project#: 13648.18.WIL Page - 8

Appendix

Log of Boring # 1 - 2

Legend to Soil Description

N

Bronze Court Fort McCoy, Wisconsin

13648.18.WIL

C

Chosen Valley Testing, Inc.

V T Legend

Boring Location

Benchmark

Benchmark: centerline of the road in the middle of the culvert, assigned elevation

100.0 feet.

* 50 = 4'' (set)

* 50 = 1'' (set)

* 50 = 0.5'' (set)

1.2

5.5

SP

19.5

SP

SM

98.7 98.2

94.4

88.4

80.4

CV

T S

TA

ND

AR

D

8.1

8.W

IL

(FO

RT

M

CC

OY

TW

IN

C

UL

VE

RT

R

EP

LA

CE

ME

NT

).G

PJ

L

OG

A

GN

NN

.G

DT

/10

/19

11.5

SM

Depth

CHOSEN VALLEY TESTING

SCALE: 1" = 4'

BPF

13648.18.WIL

Design Phase Geotechnical Evaluations Proposed Twin Culvert Replacement Bronze Court Fort McCoy, Wisconsin

See attached sketch

LOCATION:

WLUSCS

Symbol

1.7

L O G O F B O R I N G

Tests and NotesElev.

DATE: 11/28/2018

Description of Materials

(ASTM D 2487/2488)

BORING:

Gray below 6.5 feet.

POORLY GREADED SAND with SILT fine grained, brown, moist, very loose to loose.

(Fill)

SILTY SAND fine grained, brown and dark brown mixed, moist, loose to medium dense.

(Fill)

WEATHERED SANDSTONE fine grained, white, moist to water bearing, very dense.

B-1 page 1 of 1

99.9 0.0

End of boring.

Water observed around 19.5 feet during drilling.

Boring sealed upon completion.

PROJECT:

Grayish brown and trace gravel below 9 feet.

6'' SHALEY AGGREGATE BASE

13648.18.WIL

B-1

14'' AGGREGATE BASE

13.0

SP

SM

SP

Benchmark: centerline of the road in the middle of the culvert, assigned elevation

100.0 feet.

* 50 = 1'' (set)

CV

T S

TA

ND

AR

D

8.1

8.W

IL

(FO

RT

M

CC

OY

TW

IN

C

UL

VE

RT

R

EP

LA

CE

ME

NT

).G

PJ

L

OG

A

GN

NN

.G

DT

/10

/19

1.3

75.1

83.2

86.7

88.2

97.9 98.4

1.8

11.5

24.6

16.5

ML

OL

* * 50 = 1'' (set)

SM

Tests and Notes 99.7

L O G O F B O R I N G

CHOSEN VALLEY TESTING

SCALE: 1" = 4'

BPF

13648.18.WIL

Design Phase Geotechnical Evaluations Proposed Twin Culvert Replacement Bronze Court Fort McCoy, Wisconsin

See attached sketch

LOCATION:

MC = 31.6%, OC = 13.2%

PROJECT:

Description of Materials

(ASTM D 2487/2488)

DATE: 11/28/2018

USCS

SymbolElev. Depth WL

WEATHERED SANDSTONE fine grained, white, water bearing, very dense.

SILTY SAND pockets of poorly graded sand with silt in upper 6.5 feet, fine grained, brown, moist, medium dense.

(Fill)

End of boring.

Water observed around 14.5 feet during drilling.

Boring sealed upon completion.

16'' AGGREGATE BASE

POORLY GRADED SAND with SILT fine grained, light gray, moist to water bearing, medium dense to dense.

(Alluvium)

6'' SHALEY AGGREGATE BASE

Organic SANDY SILT black, wet, medium.

(Buried Topsoil)

13648.18.WIL

B-2BORING:

0.0

B-2 page 1 of 1

SAMPLE TYPES

COMPRESSIVE

STRENGTH (TSF)

SOIL GROUP NAMES & LEGEND

GRAVELS WITH FINES

>12% FINES

BLOWS/FOOT* CONSISTENCY

2.0 - 4.0

OVER 4.0

Job No. 13648.18.WIL

TERM

Trace With

Modifier

0.50 - 1.0

1.0 - 2.0

0 - 0.25

0.25 - 0.50

GW

GP

GM

GC

SW

SP

SM

SC

CL

ML

OL

CH

MH

OH

PT

CLEAN GRAVELS

<5% FINES

PRIMARILY ORGANIC MATTER, DARK IN COLOR, AND ORGANIC ODOR

WATER LEVEL (WITH TIME OF)

MEASUREMENT

0 - 4 4 - 10 10 - 30 30 - 50

OVER 50

LIQUID LIMIT (%)

CH

PL

AS

TIC

ITY

IN

DE

X

SIZE

< 12 in.

3 in. - 12 in.

#4 sieve to 3 in.

#200 sieve to #4 sieve Passing #200 sieve

TERM

Boulder Cobble Gravel Sand

Silt or Clay

SAND & GRAVEL

GROUP

SYMBOL

MC

OC

CN

DD

PP

RV

SA

P200

>50% OF COARSE

FRACTION PASSES

ON NO 4. SIEVE

RELATIVE DENSITY

(RECORDED AS BLOWS / 0.5 FT)

CL

SILT & CLAY

NUMBER OF BLOWS OF 140 LB HAMMER FALLING 30 INCHES TO DRIVE A 2 INCH O.D.

(1-3/8 INCH I.D.) SPLIT-BARREL SAMPLER THE LAST 12 INCHES OF AN 18-INCH DRIVE

(ASTM-1586 STANDARD PENETRATION TEST).

BLOWS/FOOT*

WELL-GRADED GRAVEL

POORLY-GRADED GRAVEL

SILTY GRAVEL

CLAYEY GRAVEL

WELL-GRADED SAND

POORLY-GRADED SAND

SILTY SAND

CLAYEY SAND

LEAN CLAY

SILT

ORGANIC CLAY OR SILT

FAT CLAY

ELASTIC SILT

ORGANIC CLAY OR SILT

PENETRATION RESISTANCE

LEGEND TO SOIL

DESCRIPTIONS

FINES CLASSIFY AS ML OR CL

FINES CLASSIFY AS CL OR CH

PI>7 AND PLOTS>"A" LINE

PI>4 AND PLOTS<"A" LINE

LL (oven dried)/LL (not dried)<0.75

PI PLOTS >"A" LINE

PI PLOTS <"A" LINE

LL (oven dried)/LL (not dried)<0.75

UNIFIED SOIL CLASSIFICATION (ASTM D-2487/2488)

CLEAN SANDS

<5% FINES

SANDS AND FINES

>12% FINES

INORGANIC

MOISTURE CONTENT

ORGANIC CONTENT

CONSOLIDATION

DRY DENSITY

POCKET PENETROMETER

R-VALUE

SIEVE ANALYSIS

% PASSING #200 SIEVE

LIQUID LIMIT

PLASTISITY INDEX

SWELL TEST

Unconsolidated Undrained triaxial

LL

PI

SW

UU

PERCENT

< 5

5 - 12 > 12

Relative Proportions of Fines

0 - 1 2 - 3 4 - 5 6 - 8 9 - 12 13 - 16 17 - 30

OVER 30

Hollow Stem

Standard Penetration Test

ML

MH

TEST SYMBOLS

PERCENT

< 15 15 - 29 > 30

ORGANIC

Relative Proportions of Sand and Gravel

Chosen Valley Testing, Inc.

VERY SOFT

SOFT

RATHER SOFT

MEDIUM

RATHER STIFF

STIFF

VERY STIFF

HARD

GRAVELS

TERM

Trace With

Modifier

Grain Size Terminology

Cu>4 AND 1<Cc<3

Cu>4 AND 1>Cc>3

FINES CLASSIFY AS ML OR CL

FINES CLASSIFY AS CL OR CH

Cu>6 AND 1<Cc<3

Cu>6 AND 1>Cc>3

PEAT

INORGANIC

0 10 20 30 40 50 60 70 80 90 100 110 120

MATERIAL

TYPES CRITERIA FOR ASSIGNING SOIL GROUP NAMES

ORGANIC

SANDS

CV

T

8.1 8.W

IL

(FO

RT

M

CC

OY

TW

IN

C

UL

VE

RT

R

EP

LA

CE

ME

NT

).G

PJ

1/1

0/1

CL-ML

SILTS AND CLAYS

LIQUID LIMIT>50

SILTS AND CLAYS

LIQUID LIMIT<50

>50% OF COARSE

FRACTION RETAINED

ON NO 4. SIEVE

HIGHLY ORGANIC SOILS

CO

AR

SE

-G

RA

IN

ED

S

O

IL

S >5

0% R

ET

AI

NE

D

O N

NO

. 2

S

IE

VE

FI

NE

-G

RA

IN

ED

S O

IL

S

>5 0%

P

AS

SE

S

NO

. 2

S

IE

VE

PLASTICITY CHART

" A" L I N E

VERY LOOSE

LOOSE

MEDIUM DENSE

DENSE

VERY DENSE