ATT_5_-_Geotechnical_Report_-_Final_BTSO_Geotech_Report.pdf

AG-02NV-S-15-0024 Bridger-Teton SO/District Ranger Building Construction Project Attachment 5

TABLE OF CONTENTS

GENERAL AND PROJECT DESCRIPTION

SCOPE OF SERVICES

SITE CONDITIONS

DESCRIPTION

Geology and Soil Mapping

SEISMIC HAZARD

SITE INVESTIGATIONS

FIELD INVESTIGATIONS

LABORATORY INVESTIGATIONS

SUBSURFACE CONDITIONS

SOIL PROFILES

GROUNDWATER

GEOTECHNICAL ANALYSIS

SEISMIC DESIGN PARAMETERS

LIGHT SINGLE STORY STRUCTURES

MULTI-STORY STRUCTURES: DEEP FOUNDATIONS

Driven Piles Pile Cost Opinion

RAMMED AGGREGATE PIERS

Rammed Aggregate Recommendations Allowable Bearing Pressure Settlement Cost Opinion

INTERIOR SLABS-ON-GRADE

SIDEWALKS AND EXTERIOR SLABS

CONCRETE MIX

ROADWAY AND PARKING LOT SECTIONS

CONSTRUCTION CONSIDERATIONS

EARTHWORK AND SITE GRADING

GENERAL COMMENTS

WARRANTY AND LIMITING CONDITIONS

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GENERAL AND PROJECT DESCRIPTION

This report pertains to a geotechnical investigation performed at the Bridger Teton National Forest Service compound located at 45 Rosencrans Street in Jackson, Wyoming.

The investigation is being conducted for the design and construction of Forest Supervisor’s Office which replace the existing facility. Recommendations for one and two story facilities were requested. Geotechnical recommendations contain herein are based on a preliminary site plan and description of the proposed development supplied by Case, Lowe & Hart, Inc.

and the United States Forest Service.

Scope of Services The scope of services for this investigation was to provide geotechnical recommendations based on a subsurface investigation and soils laboratory testing for the proposed facility.

The purpose of the subsurface investigation was to determine soils and groundwater characteristics. The results of the subsurface investigation and subsequent laboratory testing were utilized in an engineering analysis for foundation and paving recommendations. Slope stability analyses were not conducted, as it is our engineering judgment that the existing and proposed slope geometry and composition indicate stability.

Specific recommendations for drainage and surface water conveyance were not within the scope of work for this report.

The foundation analysis and resulting recommendations contained herein are based on typical loads for the type of structures envisioned in the conceptual design. In the final design phase of the project, it will be critical that structural loads be properly communicated to the geotechnical engineer to verify that the imposed loading conditions on the proposed foundation configuration do not cause excessive settlement, exceed the bearing capacity of the site soils, or exceed the seismic loading capacity of the foundation elements. Lateral earth pressure recommendations contained within this report are general in nature; it is critical that final retaining wall designs are reviewed by the geotechnical engineer for review and approval. For this report, it is assumed that foundation elements would not be subjected to unusual loading conditions such as eccentric loads or vibratory equipment. Unusual load conditions can induce settlement or reduce the bearing capacity of foundation elements.

SITE CONDITIONS

Description The Forest Service property and the Supervisor’s office are located in the northern part of Jackson, Wyoming. Local topography is generally flat with a gentle slope of approximately one percent descending from southeast to northwest towards Flat Creek. The facility is surrounded by lawns, mature trees, and asphalt parking areas. Various underground utilities traverse the site.

The existing Bridger Teton National Forest Supervisors Office building currently occupies the footprint of the proposed structure. The existing building is a two story structure supported by a grade beam and driven wooden pile foundation. Piles were advanced through soft swamp deposits and bear on and within underlying dense, coarse-grained, alluvial soils.

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Geology and Soil Mapping The area’s surface geology is mapped on the USGS “Geologic Map of the Jackson Quadrangle, Teton County, Wyoming,” J.D. Love, 2003. Quaternary swamp deposits are mapped just to the north, flood plain deposits are mapped at the site, and alluvial fan deposits immediately to the south and east. The surficial deposits are described as “Qfp- Flood-Plain Deposits-Sand, silt, clay, and minor lenses of gravel.” An “Qs Swamp Deposits “clays, silt, and fine sand, dark-gray and brown, rich in vegetal debris.” Soil profiles observed in the borings consist of swamp deposits underlain by alluvial fan facies at depth.

Alluvial fan deposits are described as “gravel, sand, silt and clay”; this description is similar to soils identified at depth in the borings.

The US Natural Resources Conservation Service's Soil Survey of Teton County has mapped the Greyback gravelly loam at the site. The soils are characterized as located on 0 to 3 percent slopes formed of alluvium and/or glaciofluvial deposits derived from igneous, metamorphic, and sedimentary rock. This soil is described as very deep, somewhat excessively drained, and composed of gravelly loam, very gravelly sandy loam, and very gravelly loamy sand.

Seismic Hazard Jackson Hole and the project site are located within the Intermountain Seismic Belt, a zone extending from southern Utah through eastern Idaho and western Montana, and encompassing western Wyoming and the Teton Range (Smith and Arabasz, 1991). Faults active within the Quaternary period indicated on the "Map of Quaternary Faults and Folds in Wyoming" (Machette et al, 2001) near the project site include the Teton Fault, East Gros Ventre Fault, Philips Canyon Faults, Hoback Fault, and secondary faults in the Jackson Hole Valley. In particular, the Teton Fault is thought to be capable of producing major earthquakes of a magnitude of six or greater. The postulated trace of the Teton Fault, as mapped by Love et. al., passes about six miles to the west of the project. Multiple minor earthquakes with epicenters near the site have occurred in recent years (USGS Database).

SITE INVESTIGATIONS

Field Investigations On August 14, 2014, three boreholes, BH-1 through BH-3, were excavated within the parcel.

Borehole locations are shown on the Borehole Location Drawing in the Appendix.

Boreholes were located with a Trimble GeoXT GPS unit. Borehole locations and depths were selected to determine subsurface conditions within the proposed building site. A monitoring well was installed in each borehole, and a flush mount monument and concrete apron were installed to protect each monitoring well.

IME of Riverton, Wyoming, drilled the boreholes with a CME 85 truck mounted drill rig using an 8 inch outer-diameter hollow stem auger. Andy Pruett, a Professional Geologist at Nelson Engineering, logged the boreholes and directed the sampling. Soils were classified in the field and logged by the geologist. The soil classifications, moisture conditions, and presence of organic or other notable features were recorded in the field logs. Bulk samples were sealed in plastic bags and transported to our laboratory for testing and further classification. Groundwater observations were made at the time of the excavation based on

S:\Proj2014\177-01 (Bridger-Teton National Forest Supervisor’s Office Geotech)\9 25 14 BTSO Geotech Report.docx field observations of soil moisture conditions. Field observations and laboratory testing results are presented both on the boring logs and in the test result presentation sheets in the Appendix.

The stratification lines shown on the boring logs represent the approximate boundary between soil types. The actual in-situ transition may be either gradual or abrupt. Due to the nature and depositional characteristics of natural soils and fills, care should be taken in interpolating subsurface conditions beyond the location of the boreholes. Soil conditions can change rapidly in both the lateral and vertical directions. Groundwater conditions shown on the logs are only for the dates indicated.

The subsurface conditions were interpreted from the described boreholes at the site. The soil properties inferred from the field and laboratory analyses supported by our experience formed the basis for developing our conclusions and recommendations.

Laboratory Investigations Samples obtained during the field investigation were taken to the laboratory where they were visually classified in accordance with ASTM Test Method D-2487-93, which is based on the Unified Soils Classification System. Representative samples were selected for testing to determine the physical properties of the in-place soils and to estimate engineering properties. Engineering properties of concern at this location included bearing capacity, seismic response, shear strength, and site-specific construction recommendations that are influenced by soil type and condition.

Laboratory testing was conducted to provide additional information to determine the suitability of the soils for use as foundation and subgrade materials and to verify field observations and classification estimates. The finalized laboratory observations were used to estimate soil strength and compressibility characteristics for bearing capacity determinations, consolidation and settlement determinations, lateral and vertical pile load response analysis, and pavement designs. Specific tests included Atterberg Limits Tests - ASTM Designation D4318, Grain Size Analysis - ASTM Designation C117 & C136, Soil Moisture Content Determinations - ASTM Designation D2226, and Soil Classification - ASTM Designation D2487, One-Dimensional Consolidation – ASTM Designation D2435, Unconfined Compressive Strength – ASTM Designation D2166, Water Soluble Sulfate in Soil

– ASTM Designation C1580, and soil pH.

The soil samples stored in our laboratory will be discarded after 30 days from the date this report is submitted unless we receive a specific request to retain them.

SUBSURFACE CONDITIONS

Soil Profiles Soil profiles in each of the borings consisted of swamp deposits overlying dense alluvial gravel and cobbles. Surficial soils consisted of very soft to stiff, moist to saturated silts (ML), silty clays (ML-CL), lean clays (CL), sandy silts (ML), sandy clays (ML), silty sands (SM), and gravels with sand and silt/clay (GW). These types of soils are typically deposited as lensed strata that vary in width, length, and thickness. In the borings strata thickness ranged from one inch to several feet. Standard penetration test N corresponds to very soft

S:\Proj2014\177-01 (Bridger-Teton National Forest Supervisor’s Office Geotech)\9 25 14 BTSO Geotech Report.docx to stiff consistency. Thin lenses of black organic debris and small fragments of black organic debris were observed in some the intervals of silt and clays. Swamp deposits extended to 21 foot depth in BH-1 and to approximately 23.5 feet depth in BH-2 and BH-3.

Underlying alluvium in the form of dense and very dense cobbles, gravels, and silty gravels were encountered immediately below the softer fine grained swamp deposits in all of the borings. Thin lenses of fine grained silts and clays were identified in BH-3 at about 30 foot depth. Gravels extended to the bottom depth of each boring at approximately 41.5 feet.

Groundwater Groundwater was encountered in each of the borings. Saturated soils were first encountered at depths of three to seven feet. Swamp deposits below this elevation were not uniformly saturated indicating that less permeable soils within the deposits form aquitards such that a continuous aquifer is not formed. A continuous aquifer is indicated in the underlying gravels and cobbles, which were saturated throughout.

Water levels measured in the monitoring wells on August 20, 2014 are given in Table 1 below.

Table 1 Groundwater Elevations 8/20/2014

BH #

G.S. ELEV.

(ft.)

Water Depth

BGS (ft.)

Water Surface

Elevation 1 6219.1 3.2 6215.9 2 6219.3 4.9 6214.4 3 6219.4 1.8 6217.6

Groundwater elevation will rise seasonally and in response to snowmelt and after significant rainfall events. The magnitude of these fluctuations is estimated to be less than five feet, with peak elevation during wet years tracking the elevation of Flat Creek closely.

Flat Creek flows highest during spring snowmelt and during irrigation season when water is diverted from the Gros Ventre River into the creek.

GEOTECHNICAL ANALYSIS

Subsurface conditions encountered at the site are typical of the fine grained swamp deposits found in the northern part of the Town of Jackson. The following sections discuss engineering analysis and construction recommendations for single or two story commercial structures with slab on grade floors.

Seismic Design Parameters The 2012 International Building Code (IBC) designates site class per ASCE 7 Chapter 20.

Data obtained in this investigation is not sufficient to determine soil parameters as required by ASCE 7; therefore the IBC directs that seismic coefficients and design spectra shall be determined using Site Class D and Latitude of 43.484° and Longitude of -110.762°.

If desired, a geophysical survey could be performed with a reasonably high probability that shear wave velocity findings would correspond to Site Class C.

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Light Single Story Structures One story wood frame or metal structures can be supported on conventional spread footings. A net allowable bearing capacity of 1000 psf can be accepted if three feet of soft silt and clay soils are excavated and removed and the material replaced with geogrid reinforced structural fill. Over-excavation shall extend horizontally a minimum of three feet beyond the perimeter of the footings. Reinforcement shall consist an 8 oz. nonwoven geotextile placed on the native subgrade and Tensar BX6100 (or approved equivalent) placed in the layers within the reinforced fills as shown on theDrawing in the Appendix.

Footing width is limited to a maximum width of 2 feet for continuous footings and maximum dimension of 4 feet for isolated footings. Construction of larger footings can lead to increased settlement. The net allowable soil pressure includes dead load plus maximum live load. The above loading and footing dimensions are associated with a maximum total settlement of 1.0 inches and a maximum differential settlement between footings of 0.5 inches. Lateral loads may be resisted by a coefficient of friction of 0.25 at the footing and a lateral passive bearing pressure of 130 psf per foot of depth. The above recommendations assume a depth of footing 3.5 feet below final grade for frost and structural fill depth of 6 feet below final grade.

Multi-Story Structures: Deep Foundations Multi-story, steel, masonry, and concrete buildings should be supported by deep foundation systems conveying structural loads to dense alluvial deposits. Deep foundation systems considered in this report are conventional driven steel piles and rammed aggregate piers. Drilled piers or caissons were not evaluated due to cost of advancing cased borings below the water table.

Driven Piles Allpile and Driven software were used to analyze several pile types. Software output files are given in the Appendix. Other pile types and configurations may be considered by structural designers; load capacities should be evaluated by this office for each pile type.

Recommended working load capacity, tip depth, and pile types evaluated are given in Table

1. Other combinations of depth and pile type can be evaluated if requested. Settlement for individual piles at these working loads is calculated to be less than 0.25 inches. A grade beam foundation system will be required to convey loads to driven piles. The recommendations and load limits given are for specific pile sizes.

TYPE

TIP

DEPTH

(FT)

ALLOWABLE

LOAD (KIP)

HP 12 X 53 35 29

HP 14 X 73 35 46

HP 14 X 89 35 56

Table 1.

Piles should be designed to resist lateral loading in the swamp soils using a modulus of horizontal sub-grade reaction of 30 kip/in3, E20 of 2%, and a modulus of subgrade reaction of 125/in3 for the underlying gravels. Computations for lateral loading on piles shall consider seismic loading for both base shear at the pile cap and at the surface of the deep gravel deposits.

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A Factor of Safety (FOS) of 1.5 was selected for the selection of working design loading recommended above. To achieve this FOS, dynamic testing with signal matching must be performed for a minimum of 4 production piles to be located in roughly the four quadrants of the structure footprint. Contractor or owner shall provide PDA analysis of proposed hammer and pile configuration to this office prior for review prior to mobilization.

Dynamic testing shall be conducted both to ensure the contractors hammer and driving apparatus are adequate and will not cause pile damage and to meet Factor of Safety assumptions. Piles should conform to all applicable material specifications in WYDOT Standard Specifications for Road and Bridge Construction. Dynamic testing shall be performed in general conformance with WYDOT Specifications 2010 edition. Dynamic testing results shall be reviewed by this office prior to proceeding with production pile installation.

Pile Cost Opinion The Wyoming Department of Transportation compiles weighted average base bids on an annual basis. Cost data obtained from this source and from recent bid prices for a bridge on Teton County were used to formulate the following preliminary cost opinion table. In Teton County bid prices for driven piles can vary considerably and unpredictably due to factors such as the coincident mobilization of pile driving equipment to other projects within and near Teton County.

Type Cost

Opinion/LF LF/Pile kips/Pile $/kip

HP 12 X 53 $70.00 35 30 $82

HP 14 X 73 $82.00 35 46 $62

HP 14 X 89 $90.00 35 56 $60

Table 2.

The optimum configuration should be determined based on the minimum material and installation costs that adequately support loading.

Rammed Aggregate Piers A designer of rammed aggregate foundation systems, the Geopier Foundation Company, Inc. (Geopier), was consulted regarding the suitability of a rammed aggregate pier system to support a multi story structure. Project boring logs, laboratory test results, and preliminary building footprints and structural loads were provided to Geopier for evaluation. Geopier is of the opinion that the proposed structure can be supported by strip and spread footings resting on existing soil reinforced by appropriately designed and constructed rammed aggregate elements. The piers are constructed by augering 24- to 36-inch diameter holes to depths of about 8 to 25 feet below the base of the footings and backfilling the holes with thin lifts of compacted aggregate. Alternatively, a displacement approach may be used by driving a hollow mandrel into the ground to depths of up to 40 feet, feeding aggregate through the mandrel and compacting in thin lifts. In each case, compaction is achieved using high frequency impact hammers that deliver vertical ramming energy that densifies the aggregate and increases lateral stress in the soil matrix.

The system serves to reduce settlement by replacing the compressible in the upper 23 feet below the footing with a stiffer composite soil matrix.

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The Geopier Foundation Company, Inc. recommends a net allowable bearing pressure for shallow spread footings of 2,500 at the project site if rammed aggregate piers conforming to their design are used to reinforce the subsurface conditions.

Rammed Aggregate Recommendations If a rammed aggregate pier-enhanced foundation system is selected, we recommend that the following issues be considered prior to construction.

• Specifications for rammed aggregate pier foundation systems should be prepared by a design engineer experienced in rammed aggregate pier systems licensed in the State of Wyoming.

• One demonstration pier should be installed with using standard procedures and then load-tested to determine the pier stiffness. The load testing setup and procedures should be submitted for review to the project geotechnical engineers.

The demonstration pier should be installed at the foundation grade level.

• All of the rammed aggregate pier element installations should be conducted under the observation of the geotechnical engineer’s representative to verify proper installation procedures and document any changes in the explored soil conditions.

• After the foundation soils have been reinforced with rammed aggregate elements, adequate protection of the reinforced ground is required. This includes proper drainage to eliminate ponding water and maintaining excavation distance from the installed piers. Prior to foundation installations, the reinforced ground surface should be cleared and cleaned to the satisfaction of the geotechnical engineer, and shallow foundations installed at grade.

Allowable Bearing Pressure Based on recommendations provided by Geopier Foundation Company, Inc., footings that are supported by their Rammed Aggregate Pier system may be designed for a net allowable bearing pressure not to exceed 2500 pounds per square foot (psf). Equivalent systems can be expected to achieve similar bearing capacities.

Settlement Settlement calculations should be performed by the rammed aggregate pier designers.

Based on preliminary calculations forwarded to us by Geopier Foundation Company, Inc., settlements of the aggregate-pier supported footings are estimated to be on the order of 1 inch.

Cost Opinion Rammed aggregate piers, to our knowledge, have never been constructed in Teton County or for that matter, any of the neighboring counties constituting northwestern Wyoming. Based on discussions held with ARW Engineers, the project structural consultants and the geotechnical data provided by this office, the regional GeoPier representative provided an estimate for the design and construction of a rammed aggregate foundation support system on the order of $125,000.

Interior Slabs-On-Grade In interior slab areas, a minimum of 1.75 feet thickness of the surface soils shall be excavated and removed. Interior slabs shall be founded upon the following section from top to bottom: 1) a leveling course mat 4 inches in thickness composed of a ¾-inch minus free draining material (WYDOT Grade W or equivalent) compacted to a minimum of 95% of

S:\Proj2014\177-01 (Bridger-Teton National Forest Supervisor’s Office Geotech)\9 25 14 BTSO Geotech Report.docx maximum density as determined by ASTM D 698, 2) 18 inches of structural fill, and 3) Geotex 315 ST geotextile or approved equivalent placed on native subgrade. Any excessively loose material or soft spots encountered in slab subgrade will require over-excavation and backfilling with structural fill.

All slabs should be a minimum of 4 inches thick. A moisture retardant barrier can be placed beneath all floor slabs to minimize potential ground moisture effects on floor coverings and to minimize the potential for radon infiltration. Testing for the presence of radon has not been conducted at this location. If desired, placing ASTM C33 size 5 aggregate for the granular mat beneath slabs can enhance radon remediation.

Concrete slab-on-grade control joints should be saw-cut as early as possible. Nelson Engineering recommends the use of a soft cut system, which allows saw cutting as soon as the concrete can support foot traffic. Successful crack control is dependent upon proper joint spacing. Control joints should be placed in accordance with current Portland Cement Concrete Paving Association guidelines.

Sidewalks and Exterior Slabs Sidewalks and exterior concrete slabs for foot traffic shall be placed upon a minimum of 4 inches of ¾-inch minus crushed gravel placed upon 1 foot of structural fill Any fill required to increase the elevation of slabs should meet the requirements for granular structural fill.

(Refer to the section on structural fill for requirements). Any excessively loose material or soft spots encountered in slab subgrade will require over-excavation and backfilling with structural fill.

All fill material within 2 feet of the slabs must be compacted to a minimum 95% of the maximum density as determined by ASTM D698.

Concrete Mix Per sulfate and pH testing Type II concrete is acceptable.

Roadway and Parking Lot Sections This section recommends two flexible pavement sections. One section is for existing paved areas, the other for newly paved portions of the site. Per the boreholes located in the existing parking lot to the west, the existing parking area pavement section consists of 2 inches of asphalt, 4 inches of crushed aggregate, and 1.5 feet of compacted silty gravel/gravelly silt fill. This section will support construction traffic and accommodate newly placed paving if final grade is at or higher than existing pavement elevation. In currently unpaved area and areas where the existing crushed aggregate and fill will be removed, the section given is based on providing a stable surface for construction traffic.

This section will provide a satisfactory final paved section based on the assumed traffic loading. Should a concrete pavement be desired, utilize the newly paved section given and an R value corresponding to crushed aggregate and structural fills of 70 or greater. Design traffic loading is estimated as no traffic data was available at the time of the report.

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PAVEMENT SECTION

COMPONENTS

Existing Paved Areas* Newly Paved Areas

Asphaltic Concrete 3 inches 3 inches Grade W Crushed Aggregate 6 inches 6 inches

Structural Fill subbase N/A 14 inches

N/A

TenCate RS380i Geotextile OR Tenax MS220 over 8oz

Nonwoven Geotextile Placed on Subgrade. Or Equivalents

Compacted Subgrade Surficial 8 inches of native soil compacted as much as moisture and subgrade conditions permit

*See Discussion above

CONSTRUCTION CONSIDERATIONS

Earthwork and Site Grading Excavation work and heavy equipment access will be difficult due to soft to very soft subgrades. During wet conditions, conditions will deteriorate. A protracted period of wet conditions can be expected during and after seasonal snowmelt. Placement of imported gravels supported by geotextiles and/or geogrid will be required to provide construction access and to provide platforms for equipment. Utility trenches will encounter groundwater at shallow depths. General recommendations for earthwork suitability, placement, and compaction procedures are provided below:

• Within the building footprints and areas to be paved, a minimum of 6 inches of material shall be stripped and removed. Beneath all footings, a minimum of 1 foot of material shall be stripped and removed. All organic material, deleterious undocumented fill, and debris shall be removed regardless of depth below the surface. Loose and disturbed native soils should be scarified, moisture-conditioned, and compacted. Finish surfaces shall be sloped away from foundations.

• Fill materials shall not be placed, spread, or compacted while the ground is frozen or during unfavorable weather conditions. Fill materials shall be at the proper moisture content prior to compaction and shall contain no frozen soil.

• Native subgrade shall be compacted with vibratory equipment appropriate for the soil types. Where soft and loose or over moist areas are encountered that do not improve with repeated compactive effort, replace native soils with structural fill.

• Sandy clay, clayey sand, clay, and silt soils will be encountered throughout the excavations. These soils will exhibit undesirable engineering properties when wetted. Every effort shall be made to ensure that moisture from rainfall and groundwater does not infiltrate foundation bearing, slab, and roadway

S:\Proj2014\177-01 (Bridger-Teton National Forest Supervisor’s Office Geotech)\9 25 14 BTSO Geotech Report.docx subgrade soils during the entire construction period until backfilling is complete. Measures to prevent moisture infiltration may include the placement of tarps or membranes; maintain grading during construction to drain storm water from exposed excavations during precipitation and snowmelt events, and others. In the event that moisture has been allowed to infiltrate subgrade or bearing soils, excavation and backfill operations should cease and not resume until Nelson Engineering approves the moisture and density conditions of the soils.

• Structural Fill shall consist of imported gravels (USCS classification GW or GP) with the following characteristics:

Sieve Designation Percent Passing

4” 100 ¾-inch 60-100

#4 30-50 #200 10

Fines shall have a PI of less than 15.

Structural Fill shall be placed in layers of not more than 8 inches in thickness.

Each layer of Structural Fill should be moisture conditioned to within 2% of optimum moisture content and compacted to a minimum density of 95% of the maximum dry density as determined by ASTM Designation D 698. The maximum density of material containing more than 30% oversize (greater than ¾" diameter) cannot be determined by use of the ASTM Designation D 698. In this case, a field maximum density may be determined by a test strip method. The material shall be compacted at or near optimum moisture content and a field density test shall be taken after each pass of the compaction equipment. This sequence shall continue until the maximum field density is achieved. This maximum field density shall be used for subsequent field compaction tests.

Enough density tests should be taken to monitor proper compaction.

• Safety of construction personnel including safe trenches and excavations are the responsibility of the contractor. Excavations for retaining walls and foundations shall conform to the applicable OSHA and Wyoming safety standards. Excavations and utility trenches shall be laid back to safe slopes or properly shored.

Excavations and shoring operations shall be conducted in accordance with the most recent versions of the OSHA Construction Standards for Excavations, Part 1926, Subpart P and Wyoming Public Works Standard Specifications.

Excavations for utilities shall be shored if the proper slope cannot be maintained.

• During earthwork phases of the project, a representative of Nelson Engineering shall be present to observe exposed native soils and fill materials for suitability and consistency. A documented testing program should be conducted to determine that soil compaction is in accordance with requirements.

• Backfill placed against structures (i.e., pipes and walls) shall be of a character and in a manner that will not damage that structure. In no case shall material greater

S:\Proj2014\177-01 (Bridger-Teton National Forest Supervisor’s Office Geotech)\9 25 14 BTSO Geotech Report.docx than 6 inches in diameter bear directly on or against these structures. Placing oversized material against rigid surfaces can damage the structure and interferes with proper compaction.

GENERAL COMMENTS

It is critical that the structural engineer and other project designers review this report.

When project plans and specifications are complete, a consultation with this office should be arranged to ensure compliance with this report. Additional or supplementary recommendations concerning foundations and earthwork may be required at this time.

Monitoring and testing should be performed to verify that suitable materials are used for structural fills and backfills and that fills are properly placed and compacted. Concrete testing and special inspections should be performed prior to and during placement of all concrete to ensure concrete and reinforcing steel bar comply with project plans and specifications.

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WARRANTY AND LIMITING CONDITIONS

The field observations and research reported herein are considered sufficient in detail and scope to form a reasonable basis for the purposes cited above. Nelson Engineering warrants that the findings and conclusions contained herein have been promulgated in accordance with generally accepted professional engineering practice in the fields of foundation engineering, soil mechanics, and engineering geology, only for the site described in this report. No other warranties are implied or expressed.

These engineering methods have been developed to provide the client with information regarding apparent or potential engineering conditions relating to the subject property within the scope cited above and are limited to the conditions observed at the time of the site visit and research. There is a distinct possibility that conditions may exist which could not be identified within the scope of the investigation or which were not apparent during the site investigation. The report is also limited to the information available at the time it was prepared. In the event additional information is provided to Nelson Engineering following this report, it will be forwarded to the client in the form received for evaluation by the client. This report was prepared for use by Case, Lowe & Hart, Inc. in Ogden, Utah (“Client”) and the conclusions and recommendations presented in this report are based on the agreed-upon scope of work outlined in the report and the contract for professional services between Client and Nelson Engineering (“Consultant”). Use or misuse of this report, or reliance upon the findings hereof by any parties other than the Client, is at their own risk. Neither the Client nor Consultant may make any representation of warranty to such other parties as to the accuracy or completeness of this report or the suitability of its use by such other parties for any purpose whatsoever, known or unknown, to the Client or Consultant. Neither Case, Lowe & Hart, Inc., nor Nelson Engineering shall have any liability to, or indemnifies or holds harmless third parties for any losses incurred, by the actual or purported use or misuse of this report. No other warranties are implied or expressed.

Philip Gyr, PE Geotechnical Engineer

APPENDIX

DRAWINGS

BORING LOGS

GEOTECHNICAL GENERAL NOTES

i

CORRECTED SPT: Standard Penetration Test values corrected to 60% of the theoretical free-fall hammer energy and for corrected for overburden pressure per AASHTO LRFD 6th ED Article 10.4.6.2.4.

DRILLING, SAMPLING, AND SOIL PROPERTIES ABBREVIATIONS AND SYMBOLS

N: Standard Penetration Test Uc: Unconfined compressive strength, Pounds/ft2 (PSF) Pp: Pocket Penetrometer values, Ton/ft2 (TSF) FILGC: Fragments indicate gravels and cobbles larger than split spoon diameter.

w: Water content, % LL: Liquid limit, % PI: Plasticity index, % gd: In-situ dry density, lbs/ft3 (PCF) : Ground water level SS: Split-Spoon Sample ST: Shelby Tube Sampler CS: Cylindrical Brass Lined Sample

Monitoring Well, diagonal hatching indicates screen and sand packed interval

SOIL RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION

Non-Cohesive Soils

Standard Penetration Resistance Cohesive Soils Pp-(tons/ft2)

Very Loose 0 - 4 Very Soft 0 - 0.25 Loose 4 - 10 Soft 0.25 - 0.50

Slightly Compact 8 - 15 Firm (Medium) 0.50 - 1.00 Medium Dense 10 - 30 Stiff 1.00 - 2.00

Dense 30 - 50 Very Stiff 2.00 - 4.00 Very Dense 50+ Hard 4.00+

PARTICLE SIZE

Boulders:

12 in.+

Coarse Sand:

5 mm(#4)-2 mm(#10)

Silts and Clays:

<#200

Cobbles:

12 in.-3in.

Medium Sand:

2 mm(#10)-0.4mm(#40)

Gravel:

3in.-5mm(#4)

Fine Sand:

0.4mm(#40)- 0.075mm(#200)

LABORATORY RESULTS

USCS CLASSIFICATION

Sample ID Depth (ft) 10'-11.5'

Gravel 19% Liquid Limit: 32 Sand 10% Plastic Limit: 20 Fines 71% Plasticity Index: 12

Standard Particle Tare Sample + Sample Cumulative Percent Sieve No. Size (mm) Weight (g) Tare (g) Weight (g) % Retained Passing

1.5" 38 203.6 203.6 0.0 0% 100% 1" 25 203.6 233.4 29.8 4% 96%

3/4" 18.75 203.6 229.3 25.7 8% 92% 3/8" 9.5 203.6 265.0 61.4 17% 83% #4 4.75 203.6 222.2 18.6 19% 81%

#10 2.00 203.6 211.8 8.2 21% 79% #40 0.425 203.6 213.0 9.4 22% 78%

#100 0.15 203.6 223.2 19.6 25% 75% #200 0.075 203.6 237.9 34.4 30% 70% Pan 0 203.6 697.4 493.8 100% 0%

Total Weight of Sample (g) 700.9

Moisture Content Wet Wt + Tare (g) 985.6 Dry Wt. + Tare (g) 815.0

Wt of Water (g) 170.6 Tare Wt. (g) 114.1 Dry Wt. (g) 700.9

Moisture Content 24.3% Wash Wet Wt. + Tare (g) 985.6

Pre Wash Dry (g) 700.9 Post Wash Dry (g) 207.1

Tare Wt. (g) 114.1 Wt.Of Minus #200 = 493.8

Project: Sampled By: AP Job Number Date: 8/14/2014

Visual ID: Tested By: HC Date: 8/25/2014

14-177-01 Brown Clay with Gravel

BH1-4

Unified Soils Classification

In-Situ Moisture Content

24.3%

CL (Lean Clay with Gravel)

BTSO

USCS CLASSIFICATION SIEVE CHART

0.001 0.01 0.1 1 10 100 1000

Pe rc en t P as sin g

Diameter of Particle in Millimeters

BH1-4

.002 .005 .009 .019 .037 .074 .149 .292 .420 .590 1.19 2.0 2.38 4.76 9.52 19.1 38.1 76.2 200

HR

.4 5M

IN

7H R.

M

IN

M

IN

M

IN

M

IN

M

IN

TIME READINGS

HYDROMETER ANALYSIS

SIEVE ANALYSIS

U.S. STANDARD SERIES CLEAR SQUARE OPENINGS

100 50 40 30 16 8 4 3/8" 3/4" 1-1/2" 3" 5" 6" 8"

CLAY (plastic) TO SILT (non-plastic)

SAND GRAVEL

COBBLES

FINE MEDIUM COARSE FINE COARSE

BTSO

Sample ID Depth (ft) 20'-21.5'

Gravel 0% Liquid Limit: 45 Sand 22% Plastic Limit: 44 Fines 78% Plasticity Index: 1

Standard Particle Tare Sample + Sample Cumulative Percent Sieve No. Size (mm) Weight (g) Tare (g) Weight (g) % Retained Passing

1.5" 38 203.6 203.6 0.0 0% 100% 1" 25 203.6 203.6 0.0 0% 100%

3/4" 18.75 203.6 203.6 0.0 0% 100% 3/8" 9.5 203.6 203.6 0.0 0% 100% #4 4.75 203.6 203.6 0.0 0% 100%

#10 2.00 203.6 203.9 0.3 0% 100% #40 0.425 203.6 207.7 4.1 1% 99%

#100 0.15 203.6 223.5 19.9 7% 93% #200 0.075 203.6 254.2 50.6 22% 78% Pan 0 203.6 472.8 269.2 100% 0%

Total Weight of Sample (g) 344.2

Moisture Content Wet Wt + Tare (g) 735.6 Dry Wt. + Tare (g) 454.1

Wt of Water (g) 281.5 Tare Wt. (g) 109.9 Dry Wt. (g) 344.2

Moisture Content 81.8% Wash Wet Wt. + Tare (g) 735.6

Pre Wash Dry (g) 344.2 Post Wash Dry (g) 74.9

Tare Wt. (g) 109.9 Wt.Of Minus #200 = 269.2

Project: Sampled By: AP Job Number Date: 8/14/2014

Visual ID: Tested By: HC Date: 8/25/2014

14-177-01 Gray Silt with Sand

BH2-6

Unified Soils Classification

In-Situ Moisture Content

81.8%

ML (Silt with Sand)

0.001 0.01 0.1 1 10 100 1000

Pe rc en t P as sin g

Diameter of Particle in Millimeters

BH2-6

.002 .005 .009 .019 .037 .074 .149 .292 .420 .590 1.19 2.0 2.38 4.76 9.52 19.1 38.1 76.2 200

HR

.4 5M

IN

7H R.

M

IN

M

IN

M

IN

M

IN

M

IN

TIME READINGS

HYDROMETER ANALYSIS

SIEVE ANALYSIS

U.S. STANDARD SERIES CLEAR SQUARE OPENINGS

100 50 40 30 16 8 4 3/8" 3/4" 1-1/2" 3" 5" 6" 8"

CLAY (plastic) TO SILT (non-plastic)

SAND GRAVEL

COBBLES

FINE MEDIUM COARSE FINE COARSE

BTSO

Sample ID Depth (ft) 30'-31.5'

Gravel 43% Liquid Limit: 19 Sand 55% Plastic Limit: 18 Fines 2% Plasticity Index: 1

Cu= 67 Cc= 0.23

Standard Particle Tare Sample + Sample Cumulative Percent Sieve No. Size (mm) Weight (g) Tare (g) Weight (g) % Retained Passing

1.5" 38 203.6 203.6 0.0 0% 100% 1" 25 203.6 307.8 104.2 9% 91%

3/4" 18.75 203.6 278.2 74.6 16% 84% 3/8" 9.5 203.6 343.8 140.2 28% 72% #4 4.75 203.6 372.6 169.0 43% 57%

#10 2.00 203.6 362.7 159.1 56% 44% #40 0.425 203.6 348.7 145.1 69% 31%

#100 0.15 203.6 270.6 67.0 75% 25% #200 0.075 203.6 261.5 261.5 98% 2% Pan 0 203.6 228.6 25.0 100% 0%

Total Weight of Sample (g) 1145.7

Moisture Content Wet Wt + Tare (g) 1628.9 D60= 6 Dry Wt. + Tare (g) 1483.0 D30= 0.35

Wt of Water (g) 145.9 D10= 0.09 Tare Wt. (g) 337.3 Dry Wt. (g) 1145.7

Moisture Content 12.7% Wash Wet Wt. + Tare (g) 1628.9

Pre Wash Dry (g) 1145.7 Post Wash Dry (g) 1120.7

Tare Wt. (g) 337.3 Wt.Of Minus #200 = 25.0

Project: Sampled By: AP Job Number Date: 8/14/2014

Visual ID: Tested By: HC Date: 8/25/2014

14-177-01 Brown Clay with Gravel

BH 1-8 & 3-9

Unified Soils Classification

In-Situ Moisture Content

12.7%

Particle Size (mm)

SP (Poorly Graded Sand with Gravel)

0.001 0.01 0.1 1 10 100 1000

Pe rc en t P as sin g

Diameter of Particle in Millimeters

BH 1-8 & 3-9

.002 .005 .009 .019 .037 .074 .149 .292 .420 .590 1.19 2.0 2.38 4.76 9.52 19.1 38.1 76.2 200

HR

.4 5M

IN

7H R.

M

IN

M

IN

M

IN

M

IN

M

IN

TIME READINGS

HYDROMETER ANALYSIS

SIEVE ANALYSIS

U.S. STANDARD SERIES CLEAR SQUARE OPENINGS

100 50 40 30 16 8 4 3/8" 3/4" 1-1/2" 3" 5" 6" 8"

CLAY (plastic) TO SILT (non-plastic)

SAND GRAVEL

COBBLES

FINE MEDIUM COARSE FINE COARSE

BTSO

Sample ID Depth (ft)

Gravel 46% Liquid Limit: 19 Sand 36% Plastic Limit: 17 Fines 18% Plasticity Index: 2

Standard Particle Tare Sample + Sample Cumulative Percent Sieve No. Size (mm) Weight (g) Tare (g) Weight (g) % Retained Passing

1.5" 38 203.6 203.6 0.0 0% 100% 1" 25 203.6 363.7 160.2 7% 93%

3/4" 18.75 203.6 322.0 118.5 13% 87% 3/8" 9.5 203.6 576.5 373.0 30% 70% #4 4.75 203.6 563.6 360.1 46% 54%

#10 2.00 203.6 510.3 306.8 60% 40% #40 0.425 203.6 501.4 297.8 73% 27%

#100 0.15 203.6 313.0 109.4 78% 22% #200 0.075 203.6 284.7 81.2 82% 18% Pan 0 203.6 604.2 400.7 100% 0%

Total Weight of Sample (g) 2207.5

Moisture Content Wet Wt + Tare (g) 2817.8 Dry Wt. + Tare (g) 2543.1

Wt of Water (g) 274.7 Tare Wt. (g) 335.6 Dry Wt. (g) 2207.5

Moisture Content 12.4% Wash Wet Wt. + Tare (g) 2817.8

Pre Wash Dry (g) 2207.5 Post Wash Dry (g) 1806.8

Tare Wt. (g) 335.6 Wt.Of Minus #200 = 400.7

Project: Sampled By: AP Job Number Date: 8/14/2014

Visual ID: Tested By: HC Date: 8/25/2014

25'-26.5' & 30'-31.5'

14-177-01 Gravel with Clay

BH1-7, 2-7,2-8, 3-8

Unified Soils Classification

In-Situ Moisture Content

12.4%

GM (Silty Gravel with Sand)

0.001 0.01 0.1 1 10 100 1000

Pe rc en t P as sin g

Diameter of Particle in Millimeters

BH1-7, 2-7,2-8, 3-8

.002 .005 .009 .019 .037 .074 .149 .292 .420 .590 1.19 2.0 2.38 4.76 9.52 19.1 38.1 76.2 200

HR

.4 5M

IN

7H R.

M

IN

M

IN

M

IN

M

IN

M

IN

TIME READINGS

HYDROMETER ANALYSIS

SIEVE ANALYSIS

U.S. STANDARD SERIES CLEAR SQUARE OPENINGS

100 50 40 30 16 8 4 3/8" 3/4" 1-1/2" 3" 5" 6" 8"

CLAY (plastic) TO SILT (non-plastic)

SAND GRAVEL

COBBLES

FINE MEDIUM COARSE FINE COARSE

BTSO

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

S tr ai n, Initial Dry Initial Moisture

Density (pcf) Content (%)

Boring No. BH1-4 Depth: 11.0 to 11.5' 102.7 23.1

Sampled By: Client 8/14 Date Received: 8/21/14

Soil Description: ML: silt, trace sand and clay, trace plasticity, orangish brown, saturated, loose

8/28/14

P. O. Box 80190

Billings, MT 59108-0190

Phone: 406.652.3930

Fax: 406.652.3944

Bridger Teton National Forest Supervisor's Office

Consolidation/Swell Test

SK Project Number: 08-2506 Nelson Project Number: 14-177-01

7.0

7.5

8.0

8.5

9.0

9.5

10.0 10 100 1000 10000

Stress, psf

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

S tr ai n, Initial Dry Initial Moisture

Density (pcf) Content (%)

Boring No. BH2-4 Depth: 10.0 to 12.0' 97.8 26.1

Sampled By: Client 8/14 Date Received: 8/21/14

Soil Description: ML: silt, trace sand, gravel and clay, trace plasticity, olive brown, saturated, loose

8/28/14

P. O. Box 80190

Billings, MT 59108-0190

Phone: 406.652.3930

Fax: 406.652.3944

Bridger Teton National Forest Supervisor's Office

Consolidation/Swell Test

SK Project Number: 08-2506 Nelson Project Number: 14-177-01

7.0

7.5

8.0

8.5

9.0

9.5

10.0 10 100 1000 10000

Stress, psf

Unconfined Compressive Strength of Cohesive Soil, ASTM D2166

Date: Project: 08-2506

Client: Nelson Engineering Project 14-177-01

Sample Data:

Boring: BH2-4 Sampled by: Client 8/14/14 Depth: 10.0 - 12.0' Received: 8/21/14 Description:

Specimen Information: Test Results:

Moisture, % 26.1 Unconfined strength, psi 4.2

Diameter, inches 2.87 Undrained shear strength, psi 2.1 Height, inches 4.25 Failure strain, % 13.0

L/D ratio 1.48 Strain rate, (0.5 - 2%)/minute 1.3 Wet density, pcf 143.8 Dry density, pcf 114.0

August 29, 2014 Bridger Teton National Forest

Supervisor's Office

ML: silt, trace sand, gravel and clay, trace plasticity, olive brown, saturated, loose

9.0

10.0

Joe B. DeBar Materials Lab Manager

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

C om p r e ss iv e S tr es s, p si

Axial Strain, %

Unconfined Compressive Strength of Cohesive Soil, ASTM D2166

Date: Project: 08-2506

Client: Nelson Engineering Project 14-177-01

Sample Data:

Boring: BH3-6 Sampled by: Client 8/14 Depth: 15.0 - 17.0' Received: 8/21/14 Description:

Specimen Information: Test Results:

Moisture, % 26.9 Unconfined strength, psi 5.9

Diameter, inches 2.87 Undrained shear strength, psi 2.9 Height, inches 4.875 Failure strain, % 11.3

L/D ratio 1.70 Strain rate, (0.5 - 2%)/minute 1.1 Wet density, pcf 125.7 Dry density, pcf 99.1

August 29, 2014 Bridger Teton National Forest

Supervisor's Office

ML: silt, trace gravel and clay, trace plasticity, olive brown, saturated, loose

9.0

10.0

Joe B. DeBar Materials Lab Manager

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13

C om p r e ss iv e S tr es s, p si

Axial Strain, %

ANALYTICAL SUMMARY REPORTANALYTICAL SUMMARY REPORTANALYTICAL SUMMARY REPORTANALYTICAL SUMMARY REPORT

The results as reported relate only to the item(s) submitted for testing. The analyses presented in this report were performed at Energy Laboratories, Inc., 2393 Salt Creek Hwy., Casper, WY 82601, unless otherwise noted.

Radiochemistry analyses were performed at Energy Laboratories, Inc., 2325 Kerzell Lane, Casper, WY 82601, unless otherwise noted. Any exceptions or problems with the analyses are noted in the Laboratory Analytical Report, the QA/QC Summary Report, or the Case Narrative.

If you have any questions regarding these test results, please call.

Lab ID Client Sample ID Collect Date Receive Date Matrix Test

Report Approved By:

C14081086-001 BH2-2 [2.5'-4'] 08/14/14 11:05 08/27/14 Soil E300.0 Anions pH, 1:X Water Extractable DI Water Soil Extract

Nelson Engineering Inc

Project Name: 14-177-1 BTNF Supervisors Office

Work Order: C14081086

430 S Cache

Jackson, WY 83001

September 05, 2014

Energy Laboratories, Inc. Casper WY received the following 1 sample for Nelson Engineering Inc on 8/27/2014 for analysis.

LABORATORY ANALYTICAL REPORT

Client: Nelson Engineering Inc

Project: 14-177-1 BTNF Supervisors Office

Lab ID: C14081086-001

Client Sample ID: BH2-2 [2.5'-4']

Collection Date: 08/14/14 11:05

Matrix: Soil

Report Date: 09/05/14

DateReceived: 08/27/14

Prepared by Casper, WY Branch

Analyses Result Units Analysis Date / ByRL Method

MCL/

QCLQualifiers

1:X SOIL:WATER

09/04/14 09:30 / rw0.1s.u.7.6pH, 1:1 ASA10-3

CHEMICAL CHARACTERISTICS

D 09/05/14 11:05 / ljl2mg/kg20Sulfate E300.0

D 09/05/14 11:05 / ljl0.03meq/L0.41Sulfate, 1:1 E300.0

Report

Definitions:

RL - Analyte reporting limit. MCL - Maximum contaminant level.

QCL - Quality control limit. ND - Not detected at the reporting limit.

D - RL increased due to sample matrix.

Project: 14-177-1 BTNF Supervisors Office

Work Order: C14081086

QA/QC Summary Report

09/05/14Report Date:

Analyte Result %REC RPDLow Limit High Limit RPDLimitRLUnits QualCount

Prepared by Casper, WY Branch

Method: ASA10-3 Batch: 42488

Lab ID: C14081086-001ADUP 09/04/14 09:30Sample Duplicate Run: ORION 3 STAR PH_140904B pH, 1:1 200.10 0.37.56 s.u.

Lab ID: LCS1_140904B 09/04/14 09:30Laboratory Control Sample Run: ORION 3 STAR PH_140904B pH, 1:1 99 90 1100.107.04 s.u.

Qualifiers:

RL - Analyte reporting limit. ND - Not detected at the reporting limit.

Project: 14-177-1 BTNF Supervisors Office

Work Order: C14081086

QA/QC Summary Report

09/05/14Report Date:

Analyte Result %REC RPDLow Limit High Limit RPDLimitRLUnits QualCount

Prepared by Casper, WY Branch

Method: E300.0 Analytical Run: IC2-C_140904A

Lab ID: CCV090414-5 09/05/14 08:46Continuing Calibration Verification Standard

Sulfate 99 90 1101.039.7 mg/L

Method: E300.0 Batch: 42488

Lab ID: MB-42488 09/05/14 10:30Method Blank Run: IC2-C_140904A

Sulfate 0.060.08 mg/kg

Lab ID: LCS1-42488 09/05/14 10:48Laboratory Control Sample Run: IC2-C_140904A

Sulfate 100 70 130323630 mg/kg

Lab ID: C14081086-001ADUP 09/05/14 11:23Sample Duplicate Run: IC2-C_140904A

Sulfate 201.6 2.819.3 mg/kg

Qualifiers:

RL - Analyte reporting limit. ND - Not detected at the reporting limit.

Seismic Hazard

USCSGRAPHICSLEGEND-USCS GRAPHICS LEGEND