B08_Attachment_4_Geotech_Report.pdf

Prepared for:

Bureau of Land Management

Prepared by:

North Wind Resource Consulting, LLC

March 6, 2020

30130.105-TR-001

Geotechnical Report Cleveland Lloyd Dinosaur Quarry Building (DO #105) Bureau of Land Management Vernal Field Office Price, UT

30130.026-TR-001

Geotechnical Report

Cleveland Lloyd Dinosaur Quarry Building Bureau of Land Management

July 6, 2020

Prepared for:

Bureau of Land Management

Prepared by:

North Wind Resource Consulting, LLC 1425 Higham Street

Idaho Falls, Idaho 83402

Project No. 30130.105

APPROVALS

Project No.: 30130.105

Report Number: 30130.105-TR-001

Report Name: Geotechnical Report

Bureau of Land Management

Date: July 6, 2020

Revision No.: 0

Approval by the responsible manager signifies that the document is complete, all required reviews are complete, and the document is released for use.

Originators:

Noé H. Morales, P.E. Date Civil Engineer II

Independent Technical Reviewer:

Ben L. Carter, P.E. Date Senior Geotechnical Engineer

Project Manager:

Gary Mecham, P.E. Date Project Manager

CHANGE MANAGEMENT RECORD

Project No.: 30130.105

Report Number: 30130.105-TR-001

Report Name: Geotechnical Report

Cleveland Lloyd Dinosaur Quarry Building Bureau of Land Management

Revision No. Date Description of Changes/Affected Pages

0 July 6, 2020 Base Document

Geotechnical Report v North Wind Resource Consulting, LLC Cleveland-Lloyd Dinosaur Building July 2020

CONTENTS

1. INTRODUCTION ........................................................................................................................... 1-1

1.1 Project Description ............................................................................................................. 1-1

1.2 Purpose and Scope .............................................................................................................. 1-2

1.3 Terms and Conditions / Warranties .................................................................................... 1-2

2. GENERAL DATA .......................................................................................................................... 2-1

2.1 Geologic Setting and Stratigraphy ...................................................................................... 2-1

2.2 General Geology ................................................................................................................. 2-1

2.3 Seismic Design Criteria ...................................................................................................... 2-2

2.4 Liquefaction ........................................................................................................................ 2-3

2.5 Landslide and Other Geologic Hazards .............................................................................. 2-3

3. FIELD EXPLORATION AND LABORATORY TESTING ......................................................... 3-1

3.1 Field Exploration ................................................................................................................ 3-1

3.2 Laboratory Testing ............................................................................................................. 3-1

4. SUBSURFACE CONDITIONS ...................................................................................................... 4-1

4.1 Surface Conditions ............................................................................................................. 4-1

4.2 Soils .................................................................................................................................... 4-1

4.3 Groundwater ....................................................................................................................... 4-2

5. DISCUSSION AND RECOMMENDATIONS .............................................................................. 5-1

5.1 Foundation Recommendations ........................................................................................... 5-1

5.2 Lateral Earth Pressure......................................................................................................... 5-1

5.3 Chemical and Climate Considerations ............................................................................... 5-3

5.3.1 Chemical Considerations .................................................................................... 5-3

5.4 Site Preparation and Excavation Recommendations .......................................................... 5-4

5.4.1 Climate ................................................................................................................ 5-4

5.4.2 Clearing and Grubbing ........................................................................................ 5-4

5.5 EARTHWORK .................................................................................................................. 5-4

5.5.1 Excavations and Backfill .................................................................................... 5-4

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5.5.2 Grading and Filling ............................................................................................. 5-6

5.5.3 Slope Stability and Erosion ................................................................................. 5-6

5.5.4 Drainage .............................................................................................................. 5-6

5.5.5 Rock Surface Preparation ................................................................................... 5-6

5.6 Quarry Building Seepage Control and Mitigation .............................................................. 5-7

5.6.1 Observation ......................................................................................................... 5-7

5.6.2 Foundation Construction and Foundation Drain ................................................. 5-7

5.6.3 Cutoff Trench ...................................................................................................... 5-7

5.6.4 Catch Basins Using Geosynthetic Liner ............................................................. 5-7

5.6.5 Limitations .......................................................................................................... 5-8

5.7 Structural Fill and Aggregate Recommendations ............................................................... 5-8

6. LIMITATIONS ............................................................................................................................... 6-1

7. REFERENCES ................................................................................................................................ 7-1

Geotechnical Report vii North Wind Resource Consulting, LLC

FIGURES

Figure 2-1. Project Vicinity Map. .............................................................................................................. 2-1

Figure 2-2 Screen Shot of USGS Interactive Quaternary Fault Map. ........................................................ 2-2

Figure 5-1. Effect of Wall Movement on Wall Pressures (from NAVFAC DM7.02) ............................... 5-2

Table 5-3. Chemical Testing Results Per Kleinfelder Geotechnical Report. ............................................. 5-4

TABLES

Table 2-1. 2016 ASCE-7 Seismic Design Parameters ............................................................................... 2-3

Table 5-1. Static Equivalent Fluid Pressure. .............................................................................................. 5-2

Table 5-2. Typical Properties of Compacted Soils (from NAVFAC DM 7.02). ....................................... 5-3

APPENDICES

Appendix A: Bore Hole Locations............................................................................................................ A-1 Appendix B: Bore Hole Logs ................................................................................................................... B-1

Geotechnical Report viii North Wind Resource Consulting, LLC

ACRONYMS AND ABBREVIATIONS

AASHTO American Association of State Highway and Transportation Officials ACI American Concrete Institute ASTM American Society for Testing and Materials bgs below ground surface BLM Bureau of Land Management FS factors of safety ft feet IBC International Building Code in inches LL liquid limit LRFD Load and Resistance Factor Design NAVFAC DM Naval Facilities Engineering Command Design Manual NSHMP National Seismic Hazard Mapping Project NWRC North Wind Resource Consulting, LLC OSHA Occupational Safety and Health Administration psf pounds per square foot PI plasticity index SPT Standard Penetration Test USCS United Soil Classification System USDA United States Department of Agriculture USGS United States Geological Survey

Geotechnical Report 1-1 North Wind Resource Consulting, LLC

Geotechnical Report

Bureau of Land Management Vernal Field Office

Price, UT

1. INTRODUCTION

This report presents the findings, conclusions, and recommendations of a geotechnical investigation and analysis for the Bureau of Land Management (BLM) at the existing Cleveland-Lloyd Dinosaur Quarry Site for a proposed building replacement. The project site consist of two 960 square foot steel buildings with one 2,100 square foot steel building with an elevated walkway and platforms around the interior perimeter.

The site is located approximately 30 miles south of Price, Utah and approximately 10 miles east of Cleveland, Utah. These findings, conclusions, and recommendations are based on surface and subsurface conditions encountered by Kleinfelder and American Consultants summarized in a geotechnical report titled “Renovation of Visitor Center and Quarry Facilities, Cleveland-Lloyd Dinosaur Quarry, Emery County, Utah” and dated November 29, 2004. This report was prepared in accordance to the scope of work outlined under the ID/UT IDIQ Contract No. L14PC00105, DO #105 revised on July 30, 2019. The objective of this investigation was to determine general soil and ground water conditions for use by the architect and engineer for application to the design of structures and grading plans in accordance with generally accepted geotechnical engineering practices. The report presents the results of this study. Any discrepancies

1.1 Project Description

The BLM Cleveland Lloyd Dinosaur Quarry Building project consists of existing structures of two 960 square foot steel buildings with one 2,100 square foot steel building with an elevated walkway and platforms around the interior perimeter. Original construction was completed in 1968 and it was the first visitor center operated by the BLM. The Quarry is used by many research institutions and museums and is managed for protection and scientific use and public interpretation and education of paleontological resources.

Adjacent to the visitor center are two 20’ x 48’ metal buildings constructed over portions of the dinosaur bone bed to provide protection during excavation at the site. The current buildings are not providing adequate protection for the exposed sediments and bones. This inadequate protection typically manifests its during relatively short duration thunderstorms and other high runoff events. In addition to the drainage issues, the existing buildings do not provide a good visitor experience or adequate access for visitors to view the fossils.

To alleviate these deficiencies, a single building with a footprint of approximately 20’ x 106’ is proposed to be constructed on a permanent foundation and include an elevated walkway around the interior perimeter with platforms located at points of interest. The location of the new building is proposed to be located within the existing two structures with a slight shift to the northwest. Maximum foundation loads (dead plus live) will be relatively light on the order of 5 to 10 kips. The general terrain consists of an approximate 4 percent downslope to the southeast. Based on existing topography and the location of the proposed structure relative to the existing two buildings, minimal cuts and fills are anticipated in the order of 3 to 4 feet below existing ground surface (bgs).

Geotechnical Report 1-2 North Wind Resource Consulting, LLC

1.2 Purpose and Scope

The purpose of this investigation was to explore and evaluate the subsurface conditions at the project site, and to provide geotechnical engineering recommendations based upon the findings from the geotechnical investigation documented in a geotechnical report completed by Kleinfelder and American Consultants titled “Renovation of Visitor Center and Quarry Facilities, Cleveland-Lloyd Dinosaur Quarry, Emery County, Utah” and dated November 29, 2004. In addition, sketches of the proposed building footprint and proposed location were shared by BLM. A site visit was performed on September 19, 2019 to evaluate the existing conditions.

The scope of this investigation included surface reconnaissance, review of the subsurface exploration by Kleinfelder, analysis of field and laboratory data, research of pertinent geologic literature, and report preparation. This report provides conclusions and recommendations concerning the following:

• General subsurface site conditions and geology

• Seismic Conditions

• Groundwater Conditions

• Clearing and grubbing

• Site preparation and earthwork grading

• Conventional shallow spread foundation design

• Lateral earth pressures and drainage recommendations for retaining structures

• Construction considerations including:

o Climate o Excavation and backfill o Slope stability and erosion protection o Drainage

1.3 Terms and Conditions / Warranties

This geotechnical report was written to provide test results, observations, and professional opinions regarding a specific site for a specific project. This report was prepared for BLM. The contents of this report may not be relied upon by any other party without the expressed written permission of NWRC, and the written permission of BLM. The report presents site conditions at the time of the investigation and for the aforementioned proposed development.

The geotechnical report considers only the site boundaries and construction information presented at the time of the investigation. This geotechnical report cannot be used for an adjacent lot and modifications of construction plans (i.e. size, shape, location, weight, intended use) nullifies the conclusions and recommendations contained in this report, unless indicated otherwise by the geotechnical engineer.

The site conditions which existed at the time of the geotechnical investigation can change. Conditions can only be reported at a particular time and place and no guarantee exists to ensure that recommendations will apply after natural or man-made changes occur. Examples of some possible changes include: floods, earthquakes, fluctuation of groundwater, construction activities on or next to site, demolition of existing structures, and the addition or removal of soil. The report should be updated prior to construction if a minimum of one year has elapsed from the issued date.

Our professional services were performed, the findings obtained, and our recommendations proposed in accordance with generally accepted engineering principles and practices. This warranty is in lieu of all other warranties either expressed or implied. Test findings and statements of professional opinion do not constitute a guarantee or warranty, expressed or implied.

Geotechnical Report 2-1 North Wind Resource Consulting, LLC

2. GENERAL DATA

2.1 Geologic Setting and Stratigraphy

The site is located approximately 30 miles south of Price, Utah and approximately 10 miles east of the city of Cleveland, in Emery County, Utah. (see Figure 2-1). Geological maps (Utah Geological Survey, 2004) show the site to be in an area dominated bluish-gray and gray with bands of yellow, green, maroon, brick-red and purple claystone and mudstone. It also contains thin limestones and sandstone beds with thickness varying from 150 to 250 feet. The geological layers known as the Brushy Basin Member of the Morrison Formation located on the northern margin of the San Rafael Swell that covers parts of Utah, Colorado, New Mexico, and Arizona.

The site slopes are about 1 to 8 percent in different directions relative to the existing project site.

However, the site generally slopes down to the southeast from the hill to the north. Elevation at the site is approximately 5,750 feet. Drainage is driven by sloping terrain from hills to the west and crossing to the east immediately south of the existing two structures. Vegetation consists of native grasses and shrubs.

The site is surrounded primarily by vacant land.

Figure 2-1. Project Vicinity Map.

2.2 General Geology

The geology map of the area indicates that most of the surface soils are described as Tertiary Age volcanic ash and/or mixed alluvium over bedrock. Deposits are intermixed such that they are difficult to distinguish with variable thicknesses, generally less than 20 feet thick.

Cleveland, UT

Price, UT

Cleveland-Lloyd Dinosaur Quarry Project Site

Geotechnical Report 2-2 North Wind Resource Consulting, LLC

2.3 Seismic Design Criteria

Based upon the regional geological maps of the area (see Figure 2-2) and existing literature, several active faults have been identified. These include active traces of the Joes Valley fault (30 miles west of the site and the Price River area faults located less than 1 mile south of the site (Black et al., 2006).

However, based on the fact that active faults are only considered when there is movement in the past 1,500 years, the Price River faults remain inactive (Black et al., 1999). Surface fault rupture hazards investigation is beyond the scope of work for this project.

Figure 2-2 Screen Shot of USGS Interactive Quaternary Fault Map.

Based upon the soil properties, site soils encountered at the field exploration, the project site would be classified as Site Class C in accordance with Chapter 20 of the 2016 edition of the American Society of Civil Engineers (ASCE-17). Bedrock at the site would be classified as Site Class B. The site latitude and longitude coordinates along with the soil class were used to determine the seismic design parameters using the ASCE 7 Tool. The seismic design parameter results are shown in Table 2-1 which may be used for design of structures at the subject site.

Joes Valley Fault Zone

Price River

Area Faults

Project Site

Geotechnical Report 2-3 North Wind Resource Consulting, LLC

Table 2-1. 2016 ASCE-7 Seismic Design Parameters Site Class B C

Mapped spectral acceleration for short periods SS 0.475g 0.475g

Mapped spectral acceleration for 1-second periods S1 0.12g 0.12g

Site coefficient Fa 0.9 1.3

Site coefficient Fv 0.8 1.5

Max considered earthquake spectral response acceleration for short periods SMS=FaSS 0.427g 0.617g

Max considered earthquake spectral response acceleration for 1-second periods

SM1=FvS1 0.096g 0.18g

5% damped design spectral response acceleration at short periods SDS=2/3 SMS 0.285g 0.412g

5% damped design spectral response acceleration at 1-second periods SD1=2/3 SM1 0.064g 0.12g

Peak Ground Acceleration (PGA) (%g) PGA 0.284g 0.284g

Site-Specific Peak Ground Acceleration PGAM 0.256g 0.341g

2.4 Liquefaction

Liquefaction is a phenomenon where saturated or partially saturated, relatively loose, granular soils lose their shear strength caused by an excess of pore pressure from dynamic load such as an earthquake. The results of liquefaction can have damages to structures from lateral movements as soil liquefies and settles.

If liquefaction occurs and the site is located on a sloped site, the structure may experience lateral movement known as lateral spreading.

However, due to the shallow bedrock depths, lack of groundwater presence in the upper 50 feet, and low probability of large magnitude seismic events for this area, the liquefaction potential is determined to be low.

2.5 Landslide and Other Geologic Hazards

Potential for landslide include several factors such as the slope, soil type, weather, and other geological factors. In general, the natural slopes are considered low with no major indication of potential landslide events. Nevertheless, the presence of boulders could pose a risk of rock fall in the rare occasion of a seismic event in the area.

Geotechnical Report 4-1 North Wind Resource Consulting, LLC

3. FIELD EXPLORATION AND LABORATORY TESTING

3.1 Field Exploration

The field exploration program previously conducted at the site by Kleinfelder consisting of drilling four

(4) exploratory borings to maximum depths of approximately 11 ft below the existing ground surface at the time of the field exploration. The borings were drilled using a Diedrich D-120 hollow-stem auger drill rig with rock coring capability. Standard Penetration Test (SPT) was used to establish soil consistency and collect samples at regular intervals. Soil samples were collected using a standard split-spoon sampler 140-pound hammer with an approximate 30-inch free-fall drop in accordance with the American Society for Testing and Materials (ASTM) standard D1586. Blowcounts for the last foot were logged as penetration resistance and are shown on the boring log in Appendix A. The blowcounts from the SPT sampler were utilized to determine subsurface soil characteristics for correlation with United Soil Classification System (USCS) soil types. Bedrock samples were collected using an NQ core barrel using a diamond bit. Representative bulk soil samples were obtained and preserved in plastic sample bags for possible laboratory testing. Representative samples were classified onsite by a field engineer and packaged for sample testing for final soil classification.

The boring locations relative to the existing structures are shown on the Boring Location Plan, Plate A-2 in Appendix A. The boring locations are documented in the field by sighting from features shown on the site topographic map; hence, the accuracy shown on Plate A-2 should be considered approximate.

3.2 Laboratory Testing

Laboratory tests were performed on selected representative samples to aid in soil classification and to estimate the engineering properties of the subsurface soils. The testing program included moisture content, sieve analysis (ASTM C136), and Atterberg limits test (ASTM D4318). In addition, pH resistivity, and water-soluble sulfate tests were conducted to further aid in the classification of the existing soils. Results of the laboratory tests are shown partially on the logs of each boring and are summarized in the Summary of Laboratory Test Results in Appendix B. All laboratory testing was conducted in accordance with generally accepted industry standards and appropriate ASTM standards.

4. SUBSURFACE CONDITIONS

4.1 Surface Conditions

At the time of the field exploration, the site was generally surrounded by vacant land with uneven terrain outside the existing buildings, the two buildings to the east and the visitor center at the south of the site.

The topography consisted of down sloping terrain from the west. Vegetation consisted of minimal desert bushes and desert grasses.

At the time of the writing of this report, a small berm is located northwest of the existing two structures north of the site. The berm, approximately 5 feet in height, was installed to assist in drainage redirection.

The proposed building at the site will replace the existing two building and will continue to straddle the quarry area of the site. Historically the site has been excavated from the downhill side on the east into the hillside on the west. In general, the mudstone (bone bed) strata was overlain by a sandstone layer of bedrock that was generally removed as part of the paleontological excavations. Excavations generally terminated on the bottom of the mudstone at the top of the underlying siltstones.

4.2 Soils

Based on the field exploration conducted on September 6, 2004 and laboratory testing conducted on selected soil samples, the subsurface soils were classified for the north side of the project site. The results from the exploratory program were consistent with the geological description described in Section 2.2.

Geotechnical Report 4-2 North Wind Resource Consulting, LLC

The soil subsurface conditions on the north section of the project site (borings Q-1 and Q-2), immediately adjacent to the existing two structures to the north, showed Silty GRAVEL fill material extending down

2.5 feet bgs underlain by a 12 inch high-plasticity medium stiff (fat) CLAY layer. SILTSTONE was encountered beginning at depths 3 to 4 feet extending down to approximately 8 feet bgs. This layer was followed by medium to coarse, slightly weathered to unweathered SANDSTONE extending to maximum depths of 11 feet bgs. The boring logs are shown in Appendix A.

The September 19, 2019 site visit reveled that the eastern side of the existing buildings have already been excavated of approximately 3 to 5 feet of rock material and fill in as part of the construction of the existing two buildings. The upper section of the proposed building has several additional layers of rock and soil overlying the siltstone mentioned previously. These layers as mentioned over consist of the slightly to moderately weathered MUDSTONE (bone bed) that is approximately 1.5 to 2 feet thick overlain by a slightly to moderately weathered SANDSTONE layer that is approximately 2 feet thick. The upper slopes also have additional overlaying soils, native and fill, that have deposited due to erosion and weathering.

4.3 Groundwater

Groundwater was not encountered at the time of the previous field exploration at the project location and within the approximate maximum depths explored of 11 feet bgs. However, it should be noted that groundwater levels fluctuate with seasonal changes, precipitation, and other hydrological events. It is our understanding that periodic perched groundwater flows and excessive runoff has been reported in the quarry area during relatively short duration thunderstorms.

Geotechnical Report 5-1 North Wind Resource Consulting, LLC

5. DISCUSSION AND RECOMMENDATIONS

Based on the previous field exploration and laboratory testing program, it is the engineer’s opinion that the site is suitable for construction, from a geotechnical standpoint, of the proposed new structure provided all conclusions and recommendations presented in this report are incorporated into the design and construction. The following sections present the conclusions and recommendations for the proposed site.

5.1 Foundation Recommendations

Based on the anticipated foundation loads and the soil conditions, the proposed structure may be supported on conventional strip footings established within competent sandstone, limestone, or siltstone bedrock. Based on recent voids potentially created due to erosion from runoff, footings should be embedded to the bedrock. Nevertheless, final footing design shall be evaluated by the structural engineer.

Field verification of bedrock competency during site preparation should be completed by a qualified geotechnical engineer. Footings should extend a minimum of 12 inches into the competent bedrock. This recommendation may require excavation up to 4 to 5 feet based on existing topography. When footings rest directly on bedrock, no minimum embedment for frost limiting purposes is required. Furthermore, due to the high-plasticity and expansion potential for the clay layer encountered adjacent to the existing two structures, these soils are not suitable for support of foundations and should not be reused as structural fill. Therefore, all high-plasticity clay soils encountered beneath the proposed footing locations during excavation should be removed.

Footings may be designed using a maximum net allowable bearing pressure of 4,000 pounds per square foot (psf) provided these are resting on competent bedrock. Footing width and reinforcement requirement shall be determined by the structural engineering based on building codes and structural needs. A one-third increase to the above-mentioned bearing pressure may be used for transient wind or seismic loads.

Total and differential settlement of footings are anticipated to be in the order of ½-inch and less than ½ of an inch, respectively.

Side friction acting along the base of footings on competent bedrock may be computed using a coefficient of friction of 0.5 with normal dead load. Footings resting on granular soils such as structural fill shall use a coefficient of friction of 0.4. Lateral earth pressures are included in Section 5.2.

5.2 Lateral Earth Pressure

Recommended lateral earth pressures are required for design of retaining structures including abutments, wing walls, and retaining walls. Retaining walls and below grade facilities must be designed to withstand lateral earth pressures and surcharge loads from backfill or adjacent structures. For this project, these pressures are estimated by applying recommended pressure coefficients to the estimated moist unit weight of proposed fill material to calculate an equivalent fluid pressure. If, during backfill operations, the top of the soil-retaining structure is restrained against lateral deflection at the top, the at-rest equivalent fluid pressure should be used for design. If the top is allowed to deflect away from the soil mass, the active equivalent fluid pressure may be used for design. While, if the top deflects into the soil mass or if soils are used for passive resistance, the passive equivalent fluid pressure may be used for design. An Equivalent Fluid Pressure (EFP) is calculated in the deflections that would typically generate the active and passive pressures are less than 0.5 in. for active pressures and 1.5 in. for passive pressures. These deflections are calculated based on Figure 1 of the NAVFAC DM7.2 found on page DM7.2-60, presented in Figure 5-1 below.

Geotechnical Report 5-2 North Wind Resource Consulting, LLC

Figure 5-1. Effect of Wall Movement on Wall Pressures (from NAVFAC DM7.02)

The coefficients and static lateral earth pressures recommended for design are listed in Table 5-1. These values are based on the correlated soil friction angles and bulk unit weights of typical compacted soils found in NAVFAC DM7.2, Table 1, Page 7.2-39, presented in this report as Table 5-2. The values assume non-saturated, cohesionless soils, and a horizontal backfill. If soils anticipated to be used for backfill, or a sloped backfill is anticipated, NWIT should be contacted for additional consultation.

Table 5-1. Static Equivalent Fluid Pressure.

Soil Type and

Characteristics Condition Lateral Earth Pressure Coefficient

Equivalent Fluid Pressure

Granular Cohesionless Soils φ’ = 32o

Unit Weight = 120 pcf

At-rest Ko = 0.49 56 pcf (unsaturated)

Active Ka = 0.31 37 pcf (unsaturated)

Passive Kp = 3.25 390 pcf (unsaturated)

Geotechnical Report 5-3 North Wind Resource Consulting, LLC

Table 5-2. Typical Properties of Compacted Soils (from NAVFAC DM 7.02).

In addition to the lateral earth pressures found in Table 5-1, lateral surcharge loads from heavy equipment or storage materials should be considered for design of retaining structures. Lateral surcharge loads are in addition to the above coefficients. A lateral surcharge pressure coefficient of 0.45 acting uniformly over the entire below-grade soil-retaining structure should be used to estimate surcharge loads from heavy equipment operation and storage materials.

This frictional resistance, when combined with any reliable passive resistance due to shear keys or soil embedment, shall be sufficient to resist the total lateral design forces with a minimum FS of 1.5.

5.3 Chemical and Climate Considerations

5.3.1 Chemical Considerations

Concrete durability requirements include exposure to naturally occurring chemicals in the soils. The reactivity of cement to sulfate and chloride concentrations in soils is an important factor for determining cement type. These chemical exposures include sulfates and chlorides. USGS Soil Survey Maps indicated the region as having a high potential for risk of corrosion and steel. Nevertheless, soil conditions may vary drastically within the project site and should be evaluated locally.

To determine the potential of certain areas within the project site, a series of tests were conducted previously on selected soil samples to evaluate sulfate or chloride levels. The sulfate soluble results from the selected soil samples collected indicates levels as “negligible” as shown on Table 5-3.

Geotechnical Report 5-4 North Wind Resource Consulting, LLC

Table 5-3. Chemical Testing Results Per Kleinfelder Geotechnical Report.

Boring Soil Type Depth (ft)

Sulfate (mg/kg) pH Resistivity

(ohms-cm) Conductivity

(mho/cm) B-2 Silty to Gravelly SAND 0-0.5 <10 7.4 3810 0.000277

Based on the results obtained from the chemical tests, the sulfate and chloride values reported at the Project Site are low. We recommend the use of ASTM C 150 Type II cement unless further documentation or testing at more localized areas indicate otherwise. Uncoated reinforcing steel or building steel should not be placed in direct contact with soil without having a protective coating.

5.4 Site Preparation and Excavation Recommendations

5.4.1 Climate

If construction is to be conducted during the dry seasonal conditions, many problems related to soft soils may be avoided. Lack of moisture during the dry season may cause problems with compaction of moisture sensitive soils and exposed soils. Low cohesion soils (i.e. gravels, sands, and silts) exposed in excavations may become dry, increasing the chances of sloughing or caving. Measures for these, as well as excess dust should be considered as part of the overall health and safety management plan.

Wet weather conditions present problems with soft/wet soils and must be considered as part of the construction plan. During cooler and wetter times of year, fine-grained soils such as silts and clays become unstable with increased moisture content. The presence of soft soils such as the thin clay layer encountered on the exploratory borings may cause problems during excavation during the wet season.

Prior to placement of structural fill materials or concrete, frozen soils must either be allowed to thaw or be removed to depths of non-frozen soils. Frozen soils shall not be placed as structural fill until allowed to thaw and return to optimal moisture conditions.

5.4.2 Clearing and Grubbing

The excavation boundaries should be initially cleared of all vegetation, trees, brush, roots, irrigation lines, near surface debris, organic soils, deleterious materials, and undocumented fills or disturbed soils. All vegetation and debris materials should be removed from the site. Undocumented fill, classified as soil not native to the area and/or placed without proper placement documentation should be removed and over-excavated down to undisturbed native soil or suitable bedrock. Clean top soils and disturbed soils can be stockpiled and placed as a final lift in landscaped areas only.

Remove all buried structures (i.e., foundations, pipes, abandoned utilities, or duct banks) and clean loose soils and debris from excavations. Voids resulting from removed structures shall be properly backfilled and compacted during grading operations. Any pipes less than 2 inches in diameter can be left in place provided these are backfilled with grout and capped properly.

5.5 EARTHWORK

5.5.1 Excavations and Backfill

The site soils (silty gravel) in the upper 2.5 feet can be excavated using conventional excavation equipment except for areas where bedrock may be required using rock removal techniques to reach grading levels. Expansive soils such as the fat clay layer encountered at an approximate depth of 3 feet should be removed completely and overexcavated extending down to clean competent bedrock.

Excavated expansive soils should not be used as structural fill unless approved by the geotechnical engineer.

Geotechnical Report 5-5 North Wind Resource Consulting, LLC

5.5.1.1 Soil Excavations and Backfill

Temporary shallow excavations that do not exceed 4 ft in depth may be constructed with side slopes approaching vertical, provided that proper moisture conditions are maintained. Below this depth or if trenches are allowed to dry out, the excavations may become unstable. Therefore, it is recommended that slopes be constructed in accordance with Occupational Safety and Health Administration (OSHA) regulations (29 Code of Federal Regulations [CFR], Section 1926, Subpart P). Based on these regulations, most of the onsite soils are classified as “Type C” soils and as such, excavations up to 20 ft in depth shall have a maximum slope of 1.5 foot horizontal to 1 foot vertical (1.5 H:1V).

Flatter slopes and/or shoring might be required if loose, cohesionless soils are encountered along the slope face. Sloughing of granular soils could occur if soils are allowed to dry or are wetted during rain/snow periods. Sloping and benching for excavations greater than 20 ft deep shall be designed by a registered professional engineer. Slopes will further need to be monitored by competent personnel during construction and throughout the construction process in order to protect workers from being injured from falling material and sloughing.

When open slope excavations conflict with existing buildings or utilities, or when soil conditions limit or prohibit open cut slopes, temporary excavation support (shoring) systems may need to be used.

Temporary shoring systems should be selected and installed with minimal disturbance to existing facilities. Examples of shoring systems that could be used at the site are sheet piles or pre-drilled soldier piles with pressure treated wood lagging system. It is beyond the NWRC scope of work to provide a detailed analysis for temporary shoring design. As design plans are finalized, we recommend that NWRC be retained to perform the analyses on the temporary excavation support systems and observations of slopes, as needed.

Heavy construction equipment, building materials, excavated soils and vehicular traffic should not be allowed within 1/3 of the slope height from the top of any excavation without special consideration. In addition to heavy loads on slopes, other geological hazardous features should be evaluated. Some of these hazards include discontinuities in soil layers and collapsible clays. While not encountered during field exploration activities if they are found during construction they should be evaluated for stability and maintained with good drainage. During wet weather, earthen berms or other methods should be used to prevent runoff from entering excavations.

If needed, backfill in the pipe zone (material within 6 in. below and 12 in. above the pipe) of underground utilities shall, as a minimum, consist of clean, granular materials free of clay and organic material, with 100% passing a 1-in. sieve and not more than 8% fines (passing a No. 200 sieve). See Table 4-5 for structural fill and trench fill material criteria. Trench zone backfill (material from pipe zone to subgrade) shall consist of structural fill materials placed in the structural areas (i.e., under foundation, roadways, paved areas, and other slabs) and native soils in non-structural areas. Soils used for backfill should be uniformly moisture conditioned, placed, and compacted per the structural fill section criteria. Jetting and flooding shall not be permitted for compaction of backfill. Poor compaction in utility trench backfill may cause excess settlements or unstable soils, resulting in damage to overlying structures, pavements, and slabs.

5.5.1.2 Rock Excavations and Backfill

Continuous wall footings will likely be founded on top of competent bedrock; this may require over excavation of loose highly fractured and/or irregular rock down to competent rock. Rock cuts can be made with near-vertical side slopes if care trimming is used during rock cutting.

Rock cuts or excavations required for construction of the proposed structures may be performed by numerous methods and means. These methods and means include but are not limited to, traditional mechanical means, chain trenching, and blasting. Due to the relatively small footprint of the proposed structure chain trenching and blasting are not considered viable options for this project.

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Traditional mechanical means of rock removal consist of either the use of a track hoe with hydraulic jack hammer (breaking) or a bulldozer with ripper (ripping). These mechanical methods consist of breaking the rock into pieces that are easily removed by conventional construction equipment. The track hoe with hydraulic jack hammer is not as economical as other methods but has been shown to be effective for relative small projects like this one. The bulldozer with ripper would likely not be effective due to the relatively small footprint of the foundation.

Whichever rock excavation method is selected, caution should be used to limit damage to bearing surfaces and limitation of vibrations. Over-excavation in rock may be necessary at some locations for socketing or leveling the building foundations. The recommendation for the contractor is to over-excavate until competent bedrock is reached. Competent bedrock will be determined by a qualified field geologist/geotechnical engineer. The over excavated volume may be filled with approved quality concrete.

5.5.2 Grading and Filling

After clearing and grubbing operations and any excavation cuts have been completed the subgrade soils shall be scarified a minimum of 8 in., moisture conditioned, and compacted to dry densities of 95% of the maximum dry densities obtained by the Standard Test Methods for Laboratory Compaction Characteristics of Soil, using the Modified Effort per ASTM D1557. The soil should be moisture conditioned to within 2% (plus or minus) of the optimum moisture content obtained in the same test. Fill placed on the building pads and in pavement areas, if any, should be non-expansive and placed as structural fill.

5.5.3 Slope Stability and Erosion

Stability of permanent cut and fill slopes is dependent upon shear strength, unit weight and moisture content of soils, and slope angle. Cut and fill slopes at the Site should be stable at inclinations of up to 2 horizontal to 1 vertical. However, if granular, cohesionless soils are prevalent, then a 3 horizontal to 1 vertical slope should be used. It is recommended that permanent slopes be flatter whenever feasible.

Slope performance will be primarily affected by surface runoff. Therefore, it is recommended that drainage be directed to flow away from slope faces by interceptor ditches or other means. Slope faces should further be protected from direct rain impact and melting snow by permanent erosion control measures, such as riprap, geosynthetics, and/or vegetation.

5.5.4 Drainage

Special care should be taken to ensure adequate drainage is provided throughout the life of the structure.

Final elevations at the Site should be planned so that drainage is diverted away from all structural foundations and pavement sections. Drainage grading should be sloped and maintained to carry surface water away from bearing soils and off the Site. Due to recent drainage concerns documented within the existing quarry buildings footprint, special recommendations have been included in Section 5.6.

5.5.5 Rock Surface Preparation

A qualified field geologist/geotechnical engineer is to evaluate the top of competent rock. It is recommended to retain NWRC to perform this evaluation. Following excavation to rock, the bearing surface should be cleaned with high-pressure air or water. If the bearing surface is intersected by open joints, the field geologist/geotechnical engineer will evaluate the joint width and length and determine if the characteristics of the joint are such that these should be filled with dental concrete. Dental concrete is a high density flowable concrete commonly used in construction practice. The only goal of dental concrete is to provide a flat working surface. The technique is not intended to provide any benefits, such as improved stiffness.

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5.6 Quarry Building Seepage Control and Mitigation

5.6.1 Observation

We understand that periodic seepage is observed near the base of the active quarry excavation in the northernmost quarry building. The seepage occurs shortly after storm events. Presently, this seepage is being collected and channeled in an open ditch at the base of the excavation to the east side of the building where it drains into existing drainage piping. We were requested to note this undesirable situation and comment on practical means to limit or eliminate the problem.

Based on our observations, it appears that the seepage is the result of precipitation and runoff infiltrating into the soils upslope (west) of the quarry building. The moisture likely encounters shallow bedrock and is directed toward the building. Two factors that appear to concentrate moisture upslope of the quarry building are the ravines from the hills to the west, the existing roof runoff, and surface drainage system on the upslope side of the building.

The ravines would tend to collect moisture from a relatively large surface area and concentrate it at the base of the ravines where it can infiltrate through the surface soils to the underlying bedrock and move toward the building. The roof drainage drops off both sides of the building on the west side there is a protection berm and a liner drainage system positioned on the ground next to the building. Precipitation runs off the metal roof and drops into the liner which drains to the south. It is not for sure but appears that this liner might exhibit perforation and performing poorly properly drain water away from the building.

Finally, the ground surface adjacent to the upslope side of the building slopes toward the building allowing for further concentration of moisture near the building foundation.

The following sections will provide some methods to help control the drainage and alleviate any drainage related moisture from seeping into the excavation areas within the proposed building footprint. These methods can be used in conjunction with other methods that the civil designer deems necessary to control and maintain proper drainage.

5.6.2 Foundation Construction and Foundation Drain

Construction of the new building foundation and wall shall include socketing the concrete footing into the rock surface on the upslope side of the building. It is also recommended to install a drainage system behind the foundation wall to limit hydrostatic pressures and provide a last resort for drainage protection.

The concrete wall shall be sealed and free-draining 1 inch minus washed gravel placed adjacent to the wall approximately 6 inches thick with geotextile filter fabric placed to protect gravel from migration of fines from the native soils. Alternatively a prefabricated geotextile drainage mat, such as MiraDRAIN 6000 or equivalent, can be placed in lieu of gravel. Gravel or drainage mat shall direct water to a corrugated collection pipe with perforation at the bottom with discharge away from the building.

5.6.3 Cutoff Trench

Construction of a seepage cutoff trench upslope and parallel to the building would be effective in intercepting and diverting water flow away from the building. The cutoff trench would entail excavation through the surficial soils and into the underlying bedrock a minimum of 12 inches. The trench should extend along the full length of the building and should be properly sloped to drain away and downslope from the building. Further details regarding construction of the trench (i.e., pipe, gravel, geotextile fabrics, etc.) can be provided upon request. However, since construction of this trench may impact the existing bone bed, we are presenting additional alternative recommendations for your consideration.

5.6.4 Catch Basins Using Geosynthetic Liner

We recommend that catch basins be constructed at the base of the two principal ravines located upslope of the quarry building. The catch basins could be formed by excavating the surface soils to expose bedrock and placing a geosynthetic liner material (40 mil thickness or greater) over the rock forming a

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We also recommend that the same geosynthetic liner be placed on the slope adjacent to the building. The liner should be placed to create a trough at the base of the slope and then extend up and be permanently attached to the foundation wall. This will direct all surface runoff from the slope as well as roof runoff into the trough which should be sloped toward a suitable drainage location. A four-inch corrugated plastic drainage pipe should be placed in the bottom of the trough to facilitate drainage. The liner and pipe should be covered with coarse gravel or cobbles for protection.

5.6.5 Limitations

It should be noted that these measures may not be totally effective in eliminating all seepage into the quarry area. Precipitation falling on the exposed ground upslope of the building may still be a source of moisture resulting in some seepage into the quarry area. This potential could be reduced by grading the area upslope of the building to drain surface water away from the building.

Any remaining seepage in the quarry excavation could be collected at the base of the excavation into corrugated drainage pipes as described above and directed to suitable drainage structures.

5.7 Structural Fill and Aggregate Recommendations

Structural fill will be required beneath any shallow foundations or slabs and areas adjacent to retaining wall structures except when bearing on competent rock. No significant native gravel alluvium with acceptable structural fill material was encountered during the field investigation.