Attachment_C_-_Geotechnical_Report.pdf

1301 N 3 rd

St. Superior WI 54880 715-392-7114 1-800-373-2562 F 715-392-7163 www.twinportstesting.com

Geotechnical Evaluation Report

FR 199 Culvert Replacement, Hunting Shack Creek near Orr, Minnesota

Prepared for:

USDA-Forest Service Superior National Forest

I hereby certify that this plan, specification, or 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 Minnesota.

Michael A. Haapala, PE

February 3, 2014

TPT Project Number: 13M6455F

February 5, 2014 TPT Project No. 13M6455F

John P. Jamnick, PE JPJ Engineering, Inc.

303 E. 19th Street, PO Box 656 Hibbing, Minnesota 55746

Re: Geotechnical Evaluation Report FR 199 Culvert Replacement, Hunting Shack Creek near Orr, Minnesota

Dear Mr. Jamnick:

Enclosed is our geotechnical evaluation report for the above referenced project. We have prepared this report and based our conclusions upon current applicable professional standards.

Soil samples from this project will be retained for a period of two months after the date of this report unless we are instructed in writing to do otherwise.

If you have any questions concerning the data, the recommendations presented, or if we may be of further service on this project, please contact us at (715) 392-7114. We appreciate the opportunity to be of service to you.

Respectfully submitted, Twin Ports Testing, Inc.

Martin L. Halvorson, EIT Geotechnical Engineer

Michael A. Haapala, PE

Principal Engineer

Attachment:

Geotechnical Evaluation Report

Contents

1 Introduction

1.1 Scope of Services

1.2 Proposed Project

2 Site Conditions

2.1 Geologic Setting

2.2 Site Location and Existing Conditions

2.3 Topography and Elevations

3 Field Procedures

3.1 Test Locations and Elevations

3.2 Sampling

3.3 Boring Logs

3.4 Water Level Readings

3.5 Additional Investigations/Testing

4 Subsurface Conditions

4.1 Soil

4.2 Groundwater

5 Laboratory Testing

5.1 Moisture Content

6 Analyses and Design Recommendations

6.1 Site Preparation

6.2 Shallow Foundations

6.3 Slopes

6.4 Backfill and Fill

6.5 Scour and Riprap

7 Recommendations for Construction

7.1 Excavation

7.2 Observation

7.3 Frequency of Testing

8 Limitations of Evaluation and Report

8.1 Site Variations

8.2 Design Review

8.3 Continuity of Professional Responsibility

8.4 Safe Working Conditions

8.5 Exclusive Use

Appendix: Boring Location Sketch, Boring Logs B-1 and B-2, Boring Notes/Soil Classification Data

1 Introduction

This report presents the results of our geotechnical evaluation for the proposed replacement of the Forest Road 199 culvert crossing Hunting Shack Creek, near Orr, Minnesota.

1.1 Scope of Services

The scope of this geotechnical evaluation as included in our cost estimate 13M6455, dated August 19, 2013, included:

Performing an exploration program consisting of two Standard Penetration Test (SPT) borings to nominal depths of 20 feet.

Performing laboratory tests and observations of soil samples to evaluate pertinent engineering properties of materials encountered.

Preparing a geotechnical evaluation report containing a description of the exploration program, a description of the geology and subsurface conditions encountered, groundwater conditions, boring logs with a boring location sketch, results of laboratory testing, and recommendations for foundation design.

TPT has prepared this report for design purposes only. It may not have sufficient subsurface information to prepare an accurate construction bid. TPT recommends that contractors preparing bids or proposals for this project be provided with a complete copy of this report as a supplement to the plans and specifications.

1.2 Proposed Project

It is our understanding that the proposed project will consist of replacing an existing steel culvert at the above referenced location. Potential options for the replacement structure include larger steel culverts, bottomless arches, box culverts, and bridges. Potential foundation options include spread footings and driven piles.

Site grading will consist of earthwork necessary for replacement of the proposed culvert. Cuts or fills involving permanent grade changes are assumed to be less than four feet.

Changes in the nature, design, and location of all or parts of this project may occur during the design process. The conclusions and recommendations contained in this report shall not be considered applicable to changes unless they are reviewed by the geotechnical engineer of record. TPT will then make necessary changes or modifications to this report in writing only.

2 Site Conditions

2.1 Geologic Setting

Through an understanding of the geologic history and processes of an area, we are better able to define and understand the range of geotechnical properties observed in the geological materials encountered at the site. Knowledge of the anticipated subsurface profile at the site is important for interpreting and correlating the borings from the field exploration program.

Based upon information from geologic survey reports and previous soil explorations in the area, the geology local to the site generally consists of ground moraine associated with the Des Moines Lobe of the Late-Wisconsinan Glacial Period. More specifically the Erskine Moraine Association is described as sandy, stony till, often thinly draped over bedrock hills, also containing reworked lake sediment (i.e. clay).

2.2 Site Location and Existing Conditions

The Hunting Shack River Culvert is located on Forest Route 199, about 1800 feet north east of the intersection with Forest Route 116. The existing road is gravel surfaced. Ditches slope downward on either side of the roadway. Hunting Shack Creek runs north to south through the existing culvert. Areas next to the roadway and creek are partially wooded and consist of trees and brush.

2.3 Topography and Elevations

Site topography at this location is relatively flat on either side of the roadway with some small slopes adjacent to Hunting Shack Creek. Surface elevations between the boring locations varied by less than three feet.

3 Field Procedures

The subsurface exploration program for this site consisted of two Standard Penetration Test (SPT) borings. Auger refusal on apparent bedrock was encountered in both borings at depths of about 9.5 feet.

SPT borings were performed with a CME 1050 flotation tired drill rig using hollow stem auger drilling methods. Field procedures were performed on October 30, 2013.

3.1 Boring Locations and Elevations

One SPT boring was performed at both the west and the east side of the culvert, located within the roadway surface.

3.2 Sampling

3.2.1 Standard Penetration Tests

At selected depth intervals in the borings, Standard Penetration Tests (SPT) were conducted in substantial compliance with ASTM Method D1586. The SPT “N” values shown on the boring logs are the number of blows required to drive a standard split barrel sampler 12 inches (two six-inch increments) into undisturbed soil using a 140 pound drive hammer dropped 30 inches per blow after an initial “set” of six inches. The “N” value is an index of the relative density of cohesion-less soils. Partially disturbed samples obtained from the SPT were sealed in glass jars and returned to the laboratory for testing.

3.3 Boring Logs

Field logs were prepared for each boring location by our field supervisor. These logs contain interpretation of the soil conditions observed, as described in compliance with ASTM D420 and D2488.

Final logs are included in the Appendix. The final logs represent our interpretation of the contents of the field logs after laboratory observations by our geotechnical engineer and laboratory tests of collected samples were complete. Soils are described in this report according to the Unified Soil Classification System (USCS). Boring Log Notes and Soil Classification Data can be found in the Appendix.

3.4 Water Level Readings

Water level readings were observed in the borings at the times and under the conditions stated on the boring logs. We have reviewed the data and have reported interpretations in the text of this report. However, it must be noted that fluctuations in the level of ground water may occur due to variations in rainfall, temperature, subsurface materials and other conditions or factors different from those observed at the time of our measurements. It should be noted that such conditions are subject to change.

3.5 Additional Investigations/Testing

The subsurface investigation at this site appears to be suitable for the design of shallow foundations. However, apparent shallow bedrock was encountered at this site. We recommend that a minimum of five feet of rock coring be performed to confirm the presence and quality of bedrock prior to construction.

4 Subsurface Conditions

4.1 Soil

The subsurface conditions encountered at this site consist primarily of three stratigraphic units:

(1) Fill, (2) Poorly Graded Sand, and (3) Apparent Bedrock.

4.1.1 Fill

Fill soils were encountered at the surface to a depth of 7.5 feet in boring B-1 and to a depth of 6 feet in boring B-2. Fill soils classify as poorly graded sand with silt and gravel, were fine to coarse grained, light brown in color, and were moist.

4.1.2 Poorly Graded Sand

Poorly graded sand was encountered beneath the fill in both locations to the boring termination depths. Poorly graded sand contained silt and gravel, was generally fine to medium grained, was light brown in color, and ranged in moisture content from moist to wet.

N-values from SPT sampling suggest that these soils range in relative density from medium dense to dense. Refusal was encountered in both borings on apparent rock at a depth of 9.5 feet.

4.1.3 Apparent Bedrock

Auger refusal was encountered on apparent bedrock in both boring locations at depths of about 9.5 feet. Rock outcroppings were also observed nearby the site. The presence and quality of bedrock cannot be confirmed without performing rock coring procedures at the site.

4.2 Groundwater

Groundwater was observed at a depth of six feet in both boring locations during field procedures. A detailed evaluation of groundwater levels at the site would require long term monitoring of piezometers and was not included in the scope of this evaluation.

5 Laboratory Testing

Results of the field testing and observed subsurface conditions were evaluated to develop a laboratory testing program. Laboratory testing of collected samples included visual classification by a geotechnical engineer and moisture content testing. Laboratory testing was performed in accordance with all applicable ASTM standards. Results of laboratory testing are shown on the boring logs in the Appendix.

5.1 Moisture Content

Laboratory moisture content testing was performed on collected samples from the field exploration in accordance with ASTM D2216. Values of moisture content ranged from 3% to 19%.

6 Analysis and Design Recommendations

Soil and shallow rock at this site appear to be suitable for the use of shallow foundations and culverts. Alternative feasible options include bridges and bottomless arches.

6.1 Site Preparation

Field explorations at the site encountered potential fill soils during field explorations. The conditions and compactive effort under which fill soils were placed is unknown and it is likely that these soils would settle when loaded.

We recommend stripping all surface fill soils and organic soils encountered within the footprint and influence area (1H:1V out from the outside edge of footings) of the proposed culvert and replacing with compacted engineered fill to reach design elevations. Excavations for the placement of culvert foundations should be excavated to a minimum depth of one foot below the bottom of culvert elevation to insure the removal of any hard rock projections or boulders.

6.2 Shallow Foundations

After completion of site grading and preparation, it is our opinion that the proposed culvert can be supported on shallow foundations including spread footings or culverts bearing on aggregate bedding. It is expected that culvert foundations will be placed on a minimum of six inches of MnDOT aggregate bedding (3149 G) overlying native soil. Recommendations for foundation design are provided below.

6.2.1 Net Allowable Bearing Stress

Results of the field and laboratory testing program were used to develop a soil stratigraphy for this site. Estimated soil parameters (unit weight, angle of internal friction, and soil cohesion) were calculated and used with soil mechanics principles and the Terzaghi general bearing capacity equation (Essentials of Soil Mechanics and Foundations, Seventh Edition by David F.

McCarthy, Pearson Prentice Hall 2007) to evaluate the net allowable bearing stress for proposed foundations at this site. Since foundation layouts were not provided, modification factors for inclined/eccentric loadings, square/rectangular/circular footings, footing depth, and inclined bases were not used. In our opinion, a net allowable bearing stress (with a minimum factor of safety of at least 2.5) of 3,000 psf may be used to design culvert foundations placed directly on native soil or compacted engineered fill.

Due to the presence of shallow rock, it may be desired to place foundations on clean and prepared bedrock. Allowable bearing stresses for foundations placed on rock often exceed 10,000 psf. If foundations on rock are desired, we recommend that rock coring be performed to confirm the presence and quality of rock.

6.2.2 Settlement Estimate

Replacement of the existing culvert will result in little net change in soil stresses at this location provided that dimensions and grading for the final design are similar to the existing conditions.

For culvert foundations designed for a net allowable bearing stress of 3,000 psf, we estimate total settlement of less than one inch and differential settlements less than one-half inch.

6.2.3 Modulus of Subgrade Reaction

It is our opinion that a modulus of subgrade reaction, k, of 160 pounds per square inch per inch of deflection (pci) may be used to design culvert foundations or slabs.

6.2.4 Frost Protection

We recommend that culvert foundations be placed at a minimum depth of six feet below finished exterior grade (surface of soil directly above foundation) to provide frost protection.

We also recommend that the roadway surface be a minimum of five feet above the water table to minimize frost heave.

In areas where new culvert construction ties into existing roadways, we recommend that excavations extend from the bottom of culverts at a slope of 1:20 (Vertical:Horizontal) to provide frost differential protection.

6.3 Slopes

Permanent cuts and slopes for this project should be sloped at a minimum of 3:1 (horizontal:vertical) to provide ease of construction as well as maintain long term stability.

Slopes constructed steeper than recommended should be stabilized using an approved method (such as layers of geogrid or soil nails as approved by a geotechnical engineer). A detailed slope stability analysis was not included in our scope of work.

6.4 Backfill and Fill

A wide variety of materials can be considered as suitable for engineered backfill placed in a controlled manner or for general fill soils at non-structural locations. The choice of materials is a function of structural requirements, water table conditions, seasonal construction constraints, placement and compaction methods, and other site or project specific needs. Soils which classify as SP, SP-SM, or SM in the Unified Soil Classification System (ASTM D2487) are usually the most available suitable soils for engineered backfill and fill.

For this project, we recommend that MnDOT Aggregate Bedding (3149 G) be used for direct culvert support/bedding. Suitable aggregates for backfill of over excavations or embankment construction include MnDOT Granular Borrow (3149 B) and MnDOT Granular Backfill (3149 D).

Other gradations may also be suitable as approved by the project geotechnical engineer.

Existing silty sand and poorly graded sand soils may be suitable for use as engineered backfill.

We recommend that sieve analysis of bulk samples be performed prior to construction in order to confirm material acceptability.

We recommend that a geotextile fabric (MnDOT 373, Type V or equivalent) be placed between native soils and engineered fill/aggregate bedding to promote drainage and provide separation.

6.4.2 Compaction Standard

We recommend using ASTM D1557 – Modified Proctor as the laboratory compaction standard.

6.4.3 Density

We recommend compacting each lift to a minimum of the following percentages of the above compaction standard for the respective types of fill materials as shown in Table 1.

Table 1: Compaction Recommendation

Type of Engineered Fill % Minimum Compaction

Foundation Structural Backfill 95%

Pipe Bedding 95%

Non-Structural Foundation Backfill 90%

6.4.4 Lift Thickness

Place engineered backfill and non-structural fill materials in lifts not to exceed eight inches in a loose condition, unless the contractor can demonstrate satisfactory results when placing thicker lifts. Maximum compacted lift thickness should not exceed 12 inches in a loose condition.

6.4.5 Moisture

In general, granular fill materials should be place and compacted within two percent of optimum moisture content, as determined by the above referenced compaction standard.

When the moisture content of fill materials is not in this range, compaction to the required density may be difficult if not impossible. The excavating contractor is responsible for controlling and adjusting moisture content of backfill materials.

6.5 Scour and Riprap

We recommend the use of concrete end treatments (headwalls and wingwalls) combined with riprap to prevent the erosion of embankment soils and to provide protection against scour.

Culverts foundations should be placed at an adequate depth to avoid scour. A detailed scour analysis was not included in our scope of work.

7 Recommendations for Construction

We offer the following recommendations for use during the construction of this project.

7.1 Excavation

7.1.1 Dewatering

Groundwater was encountered at a depth of about six feet in both boring locations at this site.

Groundwater is expected to be directly related to the levels of adjacent Hunting Shack Creek. If excavations extend below the groundwater surface and dewatering is necessary for construction, a large scale dewatering plan may be required. Dewatering options include diverting Hunting Shack Creek around excavations or installing temporary sheet pile cofferdams with sumps and pumps.

7.1.2 Over Sizing

Excavations for the placement of engineered backfill should extend horizontally at least a minimum of one foot beyond the bottom edge of footing for every one foot of over excavation depth required below the footing.

7.1.3 Temporary Shoring

Temporary shoring of excavations may be required for this project. Any temporary shoring systems should be designed by a registered Professional Engineer.

7.1.4 Frozen Materials

If construction occurs during temperatures below freezing, the base of all excavations and backfill materials should be protected from freezing. Excavated surfaces which become frozen should be completely thawed prior to placing backfill, concrete, or pavements. If freezing has loosened and reduce the bearing capacity of the excavation surface, remove the frozen material to the undisturbed surface. Frozen material should not be used as backfill.

7.1.5 Rock/Boulders

Difficult excavation conditions are expected involving potential bedrock or boulders. We recommend that contractors make contingencies for difficult excavation conditions.

7.2 Observation

7.2.1 Excavations

Excavation bottoms and engineered fill operations should be observed by a geotechnical engineer or a designated representative to assure that the recommendations in this report are being followed. In-place density testing should be performed to document that project specifications are met.

7.2.2 Foundations

Installation of foundations should be observed and documented by a qualified technician or engineer. We recommend that at a minimum, concrete be tested for air content, temperature, slump, and compressive strength.

7.3 Frequency of Testing

For this project, we recommend a minimum density testing frequency of one test per 1,000 square feet of backfill area per lift. If the project area is smaller than this, we recommend a minimum of one test per lift. For isolated locations or questionable areas, we recommend a minimum of one test per occasion.

8 Limitations of Evaluation and Report

8.1 Site Variations

We have based the analyses and recommendations submitted in this report in part on the data obtained from two SPT borings. The nature and extent of variations at the site will not become evident until construction. Where major variations appear it will be necessary for us to re-evaluate the recommendations contained in this report.

8.2 Design Review

As the geotechnical engineer for this project, we recommend that we be provided an opportunity to perform a general review of final plans and specifications for this project to determine that the recommendations provided have been properly interpreted and included in the design. We assume no responsibility for misinterpretation or improper application of our recommendations and conclusions by others.

8.3 Continuity of Professional Responsibility

TPT recommends that we be retained to provide geotechnical engineering services during construction. This would allow us to observe compliance with the plans, compliance with the specifications and recommendations, provide continuity of professional responsibility, and allow design changes to be made in the event that subsurface conditions differ from those anticipated.

8.4 Safe Working Conditions

Responsibility to provide safe working conditions for earthwork and below grade aspects of this project is solely that of the contractors working on the project. It appears that the on-site soils encountered are generally OSHA type B and C soils. However, our site exploration was limited to two locations and therefore excavations should be evaluated individually at the time of construction by the contractor. All local, state and federal requirements, statutes, ordinances, and building codes relating to slopes or temporary sheeting and bracing of trenches and excavations must be observed during construction.

8.5 Exclusive Use

TPT has prepared this report for the exclusive use of the USDA Forest Service and their designated representatives (JPJ Engineering), for specific application to the replacement of the Hunting Shack Creek Culvert. Professional services provided to this project by TPT were completed, findings obtained, and recommendations prepared using generally accepted engineering principles and practices. Conclusions and recommendations contained herein are based upon the applicable standards of our profession at the time this report was prepared. No warranty, express or implied, is made.

APPENDIX

CS

CS

PA

CS

PA

CS

PA

7.5

9.5

(FILL) Poorly Graded Sand with silt and gravel, fine to coarse grained, medium dense, light brown, moist

(SP) POORLY GRADED SAND with Gravel, fine to coarse grained, dense, light brown, wet

Auger Refusal at 9.5 feet End of Boring

CLIENT:

Superior National Forest Culvert Replacement

PROJECT:

11/4/13

6 ft. WD

CME Autohammer

BORING COMPLETED

CAVE IN LEVEL

CREW CHIEF

WATER LEVEL

SITE LOCATION:

JPJ Engineering, Inc.

RIG

ABBREVIATIONS: ACR-After Casing Removal, BCR-Before Casing Removal, AB-After Boring, WD-While Drilling, WS-While Sampling, NE-None Encountered, DB-Diamond Bit, RB-Rock Bit, SS-Split Spoon, ST-Shelby Tube, PA-Power Auger, MR-Mud Rotary, CS-Continuous, WL-Water Level, WO-Wash Out, WOH-Weight of Hammer, EIL-Exceeds Instrument Level, TS-Topsoil, HP-Hydraulic Probe, PP-Pocket Penetrometer

SPT HAMMER

Lou Dinnan

WATER LEVEL

JPJ Engineering

ARCHITECT - ENGINEER:

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES

IN-SITU, THE TRANSITION MAY BE GRADUAL.

BORING STARTED

10/30/13 10/30/13

REPORT DATE:

CME1050

WATER LEVEL

TPT Job No.:

13M6455F

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PLASTIC

LIMIT %

UNCONFINED COMPRESSIVE STRENGTH (TONS/FT2)

PERCENT PASSING #200 SIEVE

10 20 30 40 50

1 2 3 4 5

10 20 30 40 50

BORING LOCATION:

B-1

Hunting Shack Creek, South Side

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DESCRIPTION OF MATERIAL

WATER

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LIQUID

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LOG OF BORING

STANDARD PENETRATION N-VALUE (BLOWS/FT)

BOREHOLE LOG 13M6455F HUNGTING SHACK CREEK.GPJ TWINPORT.GDT 2/5/14

G R

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SURFACE ELEVATION:

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6.0

9.5

(FILL) Poorly Graded Sand with gravel, fine to coarse grained, loose to medium dense, light brown, moist

(SP) POORLY GRADED SAND with Gravel, light brown, wet

Auger Refusal at 9.5 feet End of Boring

CLIENT:

Superior National Forest Culvert Replacement

PROJECT:

11/4/13

6 ft. WD

CME Autohammer

BORING COMPLETED

CAVE IN LEVEL

CREW CHIEF

WATER LEVEL

SITE LOCATION:

JPJ Engineering, Inc.

RIG

ABBREVIATIONS: ACR-After Casing Removal, BCR-Before Casing Removal, AB-After Boring, WD-While Drilling, WS-While Sampling, NE-None Encountered, DB-Diamond Bit, RB-Rock Bit, SS-Split Spoon, ST-Shelby Tube, PA-Power Auger, MR-Mud Rotary, CS-Continuous, WL-Water Level, WO-Wash Out, WOH-Weight of Hammer, EIL-Exceeds Instrument Level, TS-Topsoil, HP-Hydraulic Probe, PP-Pocket Penetrometer

SPT HAMMER

Lou Dinnan

WATER LEVEL

JPJ Engineering

ARCHITECT - ENGINEER:

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES

IN-SITU, THE TRANSITION MAY BE GRADUAL.

BORING STARTED

10/30/13 10/30/13

REPORT DATE:

CME1050

WATER LEVEL

TPT Job No.:

13M6455F

SA

M

PL

E

N O

D

EP

TH

(f t)

EL

EV

AT

IO

N

(f t)

0.0

10.0

20.0

SA

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PL

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TA

N

C E

PLASTIC

LIMIT %

UNCONFINED COMPRESSIVE STRENGTH (TONS/FT2)

PERCENT PASSING #200 SIEVE

10 20 30 40 50

1 2 3 4 5

10 20 30 40 50

BORING LOCATION:

B-2

Hunting Shack Creek, North Side

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R Y

10 20 30 40 50

DESCRIPTION OF MATERIAL

WATER

CONTENT %

LIQUID

LIMIT %

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L

EV

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SA

M

PL

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TY

PE

LOG OF BORING

STANDARD PENETRATION N-VALUE (BLOWS/FT)

BOREHOLE LOG 13M6455F HUNGTING SHACK CREEK.GPJ TWINPORT.GDT 2/5/14

G R

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SURFACE ELEVATION:

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