Attachment_7_-_Geotechnical_Engineering_Study.pdf

Kumar & Associates, Inc.

TABLE OF CONTENTS

SUMMARY

PURPOSE AND SCOPE OF WORK

PROPOSED CONSTRUCTION

SITE CONDITIONS

SUBSURFACE CONDITIONS

LABORATORY TESTING

GEOTECHNICAL ENGINEERING CONSIDERATIONS

FOUNDATION RECOMMENDATIONS

FLOOR SLABS

SITE SEISMIC CRITERIA

WATER SOLUBLE SULFATES

SURFACE DRAINAGE

SITE GRADING

PAVEMENT THICKNESS DESIGN

DESIGN AND CONSTRUCTION SUPPORT SERVICES

LIMITATIONS

FIG. 1 – LOCATION OF EXPLORATORY BORINGS

FIG. 2 – LOGS OF EXPLORATORY BORINGS

FIG. 3 – LEGEND AND NOTES

FIG. 4 – SWELL-CONSOLIDATION TEST RESULTS

FIG. 5 – GRADATION TEST RESULTS

TABLE I – SUMMARY OF LABORATORY TEST RESULTS

SUMMARY

1. Two (2) exploratory borings were drilled for this study. Boring 1 encountered approximately 3.5 inches of asphalt overlying approximately 2 feet of man-placed fill consisting of poorly graded sand with silt and gravel to silty sand with gravel. The man-placed fill was underlain by natural poorly graded sand with silt and gravel to clayey sand with gravel that extended to approximately 13 feet below the ground surface which was in turn, underlain by sandstone bedrock that continued the explored depth about 25 feet. Boring 2 encountered approximately 3 inches of asphalt overlying man-placed fill consisting of poorly graded sand with silt and gravel to silty sand with gravel. The man-placed fill was underlain by natural poorly graded sand with silt and gravel to clayey sand with gravel that extended to approximately 14 feet below the ground surface which was in turn, underlain by sandstone bedrock that continued to the explored depth of about 25 feet.

Groundwater was not encountered in the borings at the time of drilling and the borings were immediately backfilled.

2. Shallow spread footing foundations should be feasible for the site. Footings placed on natural soils or properly compacted structural fill extending to natural soils should be designed for a net allowable soil bearing pressure of 3,000 psf.

3. We understand that structurally supported floors are preferred for the structures on the site. The floors would be supported on foundations the same as the building structures, and underlain by crawl spaces.

4. Flexible pavements should consist of a minimum of 4 inches of full-depth asphalt in the automobile parking areas and 5.5 inches in the drive and fire lanes. In lieu of the full-depth asphalt section, an acceptable alternate consisting of 3 inches of asphalt and 6 inches of base course may be used in the parking areas and 4 inches of asphalt overlying 6 inches of aggregate base coarse may be used in the drive and fire lanes.

A 6.0-inch Portland cement concrete pavement section may also be used in parking areas subject to automobile and light-truck traffic only. Areas subjected to combined traffic and where truck turning movements are concentrated should be paved with 7 inches of Portland cement concrete. Concrete pavement should contain sawed or formed joints to ¼ of the depth of the slab at a maximum distance of 12 feet on center.

PURPOSE AND SCOPE OF WORK

This report presents the results of a geotechnical engineering study and pavement thickness design for the proposed USFS Saratoga Bunkhouse Phase II project to be located at 2171

Wyoming-130 in Saratoga, Wyoming. The project site is shown on Fig. 1. The study was conducted for the purpose of providing geotechnical engineering recommendations, pavement thickness design and site grading considerations related to the project.

A field exploration program consisting of exploratory borings was conducted to obtain site specific information on subsurface conditions. Samples of soils and bedrock obtained during the field exploration program were tested in the laboratory to determine their classification and engineering characteristics. The results of the field exploration and laboratory testing programs were analyzed to develop geotechnical engineering recommendations for use in design and construction of the proposed development.

This report has been prepared to summarize the data obtained during this study and to present our conclusions and recommendations based on the proposed construction and the subsurface conditions encountered. Design parameters and a discussion of geotechnical engineering considerations related to construction of the proposed project are included in the report.

PROPOSED CONSTRUCTION

We understand the proposed single-story building is anticipated to have an approximate footprint of 2,400 square feet. We anticipate the buildings will be constructed with wood-framing with floor joists over a crawlspace. The area surrounding the proposed building will consist of landscaping, paved parking areas and access drives.

If the proposed construction varies significantly from that described above or depicted in this report, we should be notified to reevaluate the recommendations provided herein.

SITE CONDITIONS

The site is bounded on the west by an office building, on the south by a shop and warehouse area, and to the north and east by empty fields. At the time of our field exploration program, the site consisted of an asphalt parking lot with an existing storage shed on the northwest corner of the site. The site was relatively flat with a slight slope down to the south and east.

SUBSURFACE CONDITIONS

The subsurface conditions at the site were explored by drilling two (2) exploratory borings to depths of about 25 feet below the ground surface at the approximate locations shown on Fig. 1.

Graphic logs of the borings are presented on Fig. 2, and a legend and notes describing the soils encountered are presented on Fig. 3.

Boring 1 encountered approximately 3.5 inches of asphalt overlying approximately 2 feet of man-placed fill consisting of poorly graded sand with silt and gravel to silty sand with gravel.

The man-placed fill was underlain by natural poorly graded sand with silt and gravel to clayey sand with gravel that extended to approximately 13 feet below the ground surface which was in turn, underlain by sandstone bedrock that continued the explored depth about 25 feet. Boring 2 encountered approximately 3 inches of asphalt overlying man-placed fill consisting of poorly graded sand with silt and gravel to silty sand with gravel. The man-placed fill was underlain by natural poorly graded sand with silt and gravel to clayey sand with gravel that extended to approximately 14 feet below the ground surface which was in turn, underlain by sandstone bedrock that continued to the explored depth of about 25 feet.

The man-placed fill material was fine to coarse grained with gravel, moist, and brown to dark brown. The natural granular soils were fine to coarse grained, moist and brown. The sandstone bedrock was fine to coarse grained with occasional cemented layers, moist, and gray to light brown. Based on sampler penetration resistance, the natural granular soils were generally medium dense to very dense and the sandstone bedrock was hard to very hard.

Groundwater was not encountered in the borings at the time of drilling and the borings were immediately backfilled. Groundwater levels are expected to fluctuate with time, and may fluctuate upward after wet weather or subsequent to landscape irrigation.

LABORATORY TESTING

Laboratory testing was performed on selected samples obtained from the borings to determine in-situ moisture content and dry density, Atterberg limits, gradation, swell-consolidation characteristics, and water soluble sulfates. The results of the laboratory tests are shown next to the boring logs on Fig. 2, graphically plotted on Figs. 4 and 5, and summarized in the attached

Table I.

The testing was conducted in general accordance with recognized test procedures, primarily those of the American Society for Testing of Materials (ASTM) and the Wyoming Department of

Transportation (WYDOT).

Swell-Consolidation: Swell-consolidation testing was conducted on a selected sample of the overburden materials in order to evaluate the compressibility and swell characteristics under loading and when submerged in water. The sample was prepared and placed in a confining ring between porous discs, subjected to a surcharge pressure of 1,000 psf and allowed to consolidate before being submerged. The sample height was monitored until deformation practically ceased under each load increment.

Results of the swell-consolidation tests are plotted as a curve of the final strain at each increment of pressure against the log of the pressure and are presented on Fig. 4. Based on the results of the laboratory swell-consolidation testing, a sample of natural clayey sand with gravel exhibited no movement upon wetting under a 1,000-psf surcharge pressure.

Index Properties: Samples were classified into categories of similar engineering properties in general accordance with the Unified Soil Classification System. This system is based on index properties, including liquid limit and plasticity index and gradation characteristics. Values for moisture content and dry density, liquid limit and plasticity index, and the percent of soil passing the U.S. No. 4 and No. 200 sieves are presented in Table I and adjacent to the corresponding sample on the boring logs.

GEOTECHNICAL ENGINEERING CONSIDERATIONS

Without documentation of placement conditions including density testing documenting the degree of compaction, the existing fill materials are considered non-engineered and generally not suitable for support of foundations or floor slabs.

Criteria for shallow spread footing foundations are presented below; however, it is very important to the long-term performance of the building that all of the existing fill materials be removed from below the proposed foundation elements and floor slabs and to a distance beyond the building area as outlined in Item 7 of the “Foundation Recommendations” section below. In our opinion, the removed fill, excluding deleterious materials, is suitable to be moisture conditioned and recompacted as structural fill below foundation elements, floor slabs and exterior flatwork. We have no way to accurately predict the total magnitude of potential settlements if the existing fill is left in place; however, movements exceeding 1-inch are possible. As discussed above, to reduce settlement potential, all existing fills beneath planned foundations and slabs-on-grade should be removed and replaced with structural fill.

FOUNDATION RECOMMENDATIONS

Considering the subsurface conditions encountered in the exploratory boring and the nature of the proposed construction, we recommend that structures on the site be founded on spread footings placed on undisturbed natural soils or properly compacted structural fill extending to undisturbed natural soils.

The design and construction criteria presented below should be observed for a spread footing foundation system. The construction details should be considered when preparing project documents.

1. Footings placed on structural fill extending to undisturbed natural soils should be designed for an allowable soil bearing pressure of 3,000 psf.

2. Based on experience we estimate total settlement for footings designed and constructed as discussed in this section will be less than 1-inch. Differential settlements across the building are estimated to be less than ½ to ¾ of the total settlement.

3. Spread footings should have a minimum footing width of 16 inches for continuous footings, and 24 inches for isolated pads.

4. Exterior footings and footings beneath unheated areas should be provided with adequate soil cover above their bearing elevation for frost protection. Placement of foundations at least 54 inches below the exterior grade is typically used in this area.

5. The lateral resistance of a spread footing placed on undisturbed natural soils and/or properly compacted structural fill material will be a combination of the sliding resistance of the footing on the foundation materials and passive earth pressure against the side of the footing. Resistance to sliding at the bottoms of the footings can be calculated based on an allowable coefficient of friction of 0.35. Passive pressure against the sides of the footings can be calculated using an equivalent fluid pressure of 200 psf. The values recommended above assume mobilization of the ultimate soil strength. The above values are working values.

6. Continuous foundation walls should be reinforced top and bottom to span an unsupported length of at least 10 feet.

7. Structural fill placed against the sides of the footings to resist lateral loads should consist of moisture-conditioned on-site soils or imported non-expansive granular fill. The structural fill should be compacted as listed in the “Site Grading” section of this report.

New fill should extend down from the edges of the footings at a 1 horizontal to 1 vertical projection

8. Areas of loose or soft material or existing fill encountered within the foundation excavations should be removed and the footings extended to adequate natural bearing material. Alternatively, the loose or soft material or existing fill may be removed and replaced with structural fill. The structural fill should be compacted as listed in the “Site

Grading” section of this report. Structural fill should extend down from the edges of the footings at a 1 horizontal to 1 vertical projection.

9. Granular foundation soils should be densified with a smooth vibratory compactor prior to placement of concrete.

10. Care should be taken when excavating the foundations to avoid disturbing the supporting materials. Excavation methods that reduce soil disturbance, such as hand excavation or careful soil removal with a backhoe positioned outside of the excavation may be required.

11. A representative of the project geotechnical engineer should observe all footing excavations prior to concrete placement.

FLOOR SLABS

Based on discussions with the design team, we understand that a structural floor above a well-ventilated crawl space is the preferred method of construction for the proposed building. The floor should be supported on shallow foundations the same as the main structure.

Design of a crawl space or underfloor void should consider drainage and moisture control. We recommend a minimum 12-inch void beneath floors. Providing a full crawl space (3 feet or more) rather than a 12-inch void beneath the floor has the advantages that utilities can be suspended above the expansive subgrade and crawl space surface drainage can be provided.

Utility lines should not be supported on the subgrade, unless adequate measures are taken to account for differential movement between grade supported utilities and slabs. If utilities are connected to the floor or floor openings, void spaces should also be provided below the utility lines. The utility lines should be supported by suitable means such as hangers as necessary.

We recommend that void and crawl spaces be designed with positive surface drainage and a collection point or outlet so that free-water introduced into these spaces can be removed. High humidity can develop in crawl spaces due to the transmission of water vapor through moist soils. Crawl space humidity should be controlled through ventilation and/or the use of a vapor barrier on the crawl space floor or on the underside of the structure floor.

SITE SEISMIC CRITERIA

Saratoga is located in a low seismic activity area. The soil profile consists generally of relatively dense overburden soils overlying hard bedrock. The overburden materials will generally classify as International Building Code (IBC) Site Class D. Based on our experience with similar subsurface profiles in the area, we recommend a design soil profile of IBC Site Class D. Based on the subsurface profile, and site seismicity, liquefaction is not a design consideration.

WATER SOLUBLE SULFATES

The concentrations of water-soluble sulfates measured in a sample of the overburden soils obtained from the exploratory borings was 0.00%. These concentrations of water-soluble sulfates represent a Class 0 severity exposure to sulfate attack on concrete exposed to these materials.

The degree of attack is based on a range of Class 0, Class 1, Class 2, and Class 3 severity exposure as presented in ACI 201. Based on the laboratory test results, we believe special sulfate resistant cement will generally not be required for concrete exposed to the on-site soils.

SURFACE DRAINAGE

Proper surface drainage is very important for acceptable performance of the facility during construction and after construction has been completed. Drainage recommendations provided by local, state and national entities should be followed based on the intended use of the facility.

The following recommendations should be used as guidelines and changes should be made only after consultation with the geotechnical engineer.

1. Excessive wetting or drying of foundation and slab subgrades should be avoided during construction.

2. The ground surface surrounding the exterior of the buildings and exterior flatwork and paved areas should be sloped to drain away in all directions. We recommend a minimum slope of 6 inches in the first 10 feet in unpaved areas and a minimum slope of

3 inches in the first 10 feet in impervious flatwork and paved areas. Site drainage beyond the 10-foot zone should be designed to promote runoff and reduce infiltration.

These slopes may be changed as required for handicap access points in accordance with the Americans with Disabilities Act.

3. To promote runoff, the upper 1 to 2 feet of the backfill adjacent to buildings should be a relatively impervious on-site soil or be covered by flatwork or a pavement structure.

4. Exterior backfill should be adjusted to near optimum moisture content (generally optimum to +3% of optimum unless indicated otherwise in this report) and compacted to at least 95% of the standard Proctor (ASTM D698) maximum dry density.

5. Ponding of water should not be allowed in backfill material or in a zone within 10 feet of the building foundations, whichever is greater.

6. Roof downspouts and drains should discharge well beyond the limits of all backfill.

SITE GRADING

Site Preparation: Based on our understanding of the proposed construction and observed site topography, site grading within the building footprint is expected to consist of minimal cuts and fills. Material types encountered during site grading will generally consist of clayey to granular materials. These materials can be excavated during site grading operations with moderate to heavy-duty earth moving equipment.

Existing fills, where present, are considered non-engineered and unsuitable in their current condition for support of foundations, floor slabs, settlement-sensitive exterior flatwork, and pavements unless properly prepared. Proper preparation should include complete removal of existing fill from beneath foundations, floor slabs, settlement sensitive flatwork, and rigid pavements.

The on-site overburden soils, including the existing fills, should be suitable for use as general site fill and as structural fill beneath foundations and slabs, provided they do not contain organic or other deleterious materials.

Temporary Excavations and Dewatering: Temporary excavations should be constructed in accordance with OSHA requirements, as well as state, local and other applicable requirements.

Site excavations will encounter existing fill and natural granular soils that classifying as OSHA

Type C soils, although loose areas of fill may classify as OSHA Type D soils. Excavations encountering loose granular soils, or groundwater, will require much shallower side slopes than those allowed by OSHA and/or temporary shoring.

In our opinion, conventional hydraulic excavation equipment can be used for excavation of the existing fill materials and underlying natural soils. Excavated slopes may soften due to construction traffic and erode from surface runoff. Measures to keep surface runoff from excavation slopes, including diversion berms, should be considered.

Cut and Fill Slopes: Permanent unretained cuts in the overburden soils and fill slopes up to 10 feet high should be constructed at a 2H:1V (horizontal to vertical) or flatter inclination for stability purposes and at a 3H:1V or flatter inclination for limiting the potential for erosion.

If groundwater seepage is encountered during or prior to cut slope excavation, a stability evaluation should be conducted to determine if the seepage would adversely affect the cut.

Material Specifications: Unless specifically modified in the preceding sections of this report, the following recommended material and compaction requirements are presented for compacted fills on the project site. A geotechnical engineer should evaluate the suitability of all proposed fill materials for the project prior to placement.

1. Structural Fill beneath Footings, Slab-on-Grade Floors, and Settlement-Sensitive

Exterior Flatwork: Structural fill should consist of moisture conditioned on-site soils or, if necessary, imported non-expansive soils with a maximum of 60% passing the No. 200 sieve, a maximum Liquid Limit of 30, and a maximum Plasticity Index of 12. Fill source materials, including on-site soils, not meeting one or more of these criteria may be acceptable if they meet the swell criteria presented in Item 6 below.

2. Site Grading Fill Beneath Pavements and Movement-Tolerant Exterior Flatwork:

Compacted fill should consist of moisture-conditioned on-site materials or non-expansive imported soil materials.

3. Pipe Bedding Material: Pipe bedding material should be a free draining, coarse-grained sand and/or fine gravel. The near-surface on-site soils generally consist of clay soils and sands within relatively high silt and/or clay content and are not considered suitable for pipe bedding.

4. Utility Trench Backfill: Materials excavated from the utility trenches may be used for trench backfill above the pipe zone fill provided they do not contain unsuitable material or particles larger than 4 inches and can be placed and compacted as recommended herein.

5. Base Course: Base course placed in conjunction with pavements should consist of material meeting the requirements of WYDOT Grading GR or L Base Criteria.

6. Material Suitability: Unless otherwise defined herein, all fill material should be a non-expansive soil free of vegetation, brush, sod, trash and debris, and other deleterious substances, and should not contain rocks or lumps having a diameter of more than 4 inches. A fill material should be considered non-expansive if the swell potential of the material, when remolded to 95% of the standard Proctor (ASTM D698) maximum dry density at optimum moisture content, does not exceed 0.5% when wetted under a 200 psf surcharge pressure. If grading is performed during times of freezing weather, the fill should not contain frozen materials, and, if the subgrade is allowed to freeze, all frozen material should be removed prior to additional fill placement or footing, slab or pavement

Based on the data from the borings and results of the laboratory testing, the on-site soils should be suitable for reuse as compacted site grading fill and as structural fill.

Evaluation of potential structural fill sources, particularly those not meeting the above liquid limit and plasticity index criteria for imported fill materials, should include determination of laboratory moisture-density relationships and swell-consolidation tests on remolded samples prior to acceptance.

Compaction Requirements: We recommend the following compaction criteria be used on the project:

1. Moisture Content: Fill materials should be compacted at moisture contents within 2 percentage points of the optimum moisture content for predominantly granular materials and between 0 and +3 percentage points of optimum for predominantly cohesive materials, if used. The contractor should be aware that clay materials, including on-site and imported materials, may become somewhat unstable and deform under wheel loads if placed near the upper end of the moisture range.

2. Placement and Degree of Compaction: Unless otherwise defined herein, compacted fill should be placed in maximum 8-inch-thick loose lifts. The following compaction criteria should be followed during construction:

Percentage of Maximum Standard Proctor Density

Fill Location ...................................................................................... (ASTM D-698) Beneath Spread Footing Foundations ........................................................... 100% Adjacent to Foundations .................................................................................. 95% Beneath Floor Slabs, Settlement-Sensitive Flatwork Areas and Pavements1 . 95% Utility Trenches ................................................................................................ 95% Landscape and Other Areas ............................................................................ 90%

1 Aggregate base course should be compacted to a minimum of 95 percent of the modified Proctor (ASTM D 1557) maximum dry density at moisture contents within 2 percentage points of optimum.

3. Subgrade Preparation: Areas receiving new fill should be prepared as recommended in specific sections of this report to provide a uniform base for fill placement. All other areas to receive new fill not specifically addressed herein should be scarified to a depth of at least 8 inches and recompacted to at least 95% of the standard Proctor (ASTM

D698) maximum dry density at the moisture contents recommended above.

Subgrade preparation should include proofrolling with a heavily loaded pneumatic-tired vehicle or a heavy, smooth-drum roller compactor. Areas that deform excessively during proofrolling should be removed and replaced to achieve a reasonably stable subgrade prior to placement of compacted fill or slabs, flatwork or pavements.

UNDERDRAIN SYSTEM

We recommend that the foundation be protected by an underdrain system. Although groundwater was not encountered in our explorations at depths near the proposed foundation elevation, it has been our experience that local perched groundwater may develop during times of heavy precipitation, snow melt, or seasonal irrigation. If an underdrain system is not constructed, the below ground walls should be designed for the full hydrostatic pressure conditions. We also recommend a standby pump be available to discharge water that may develop in the below ground areas.

The drain system should consist of rigid drainpipe placed in the bottom of a trench or the exterior side of the foundation and surrounded above the invert level with free-draining granular material. Free-draining granular material used in the drain system should contain less than 5% passing the No. 200 sieve, less than 35% passing the No. 4 sieve and have a maximum size of

2 inches. The free-draining backfill should be hydraulically connected to the drainage zone on the exterior face of the walls discussed above. The perimeter drains should be at least 4 inches in diameter. The drain lines should be placed at least 1 foot below the floor level and graded to sumps at a minimum slope of 1/2%. The granular underdrain system should be sloped to a sump or multiple sumps where water can be removed by pumping or gravity drainage.

Standby pump capacity should be provided in the event of pump failure. We also believe an overdesigned pump capacity is desirable in the event groundwater conditions change.

PAVEMENT THICKNESS DESIGN

A pavement section is a layered system designed to distribute concentrated traffic loads to the near surface subgrade. Performance of the pavement structure is directly related to the physical properties of the subgrade soils and traffic loadings. Soils are represented for pavement design purposes by means of a soil support value for flexible pavements and a modulus of subgrade reaction for rigid pavements. Both values are empirically related to strength.

Subgrade Materials: Based on the results of the field and laboratory studies, the majority of the near-surface subgrade materials at the site classify as A-1-b and A-6 with group indices between 0 and 2 in accordance with the American Association of State Highway and

Transportation Officials (AASHTO) classification. For design purposes, a resilient modulus value of 5,000 psi was selected for flexible pavements and a modulus of subgrade reaction of

50 pci was selected for rigid pavements.

Design Traffic: Since anticipated traffic loading information was not available at the time of this report preparation, an 18-kip equivalent single axle loading (ESAL) value of 20,000 was assumed for the paved parking surfaces and an ESAL of 73,000 was assumed for truck routes.

The values are selected based on our past experience for facilities of this nature. We frequently identify a “Light Duty” and a “Heavy Duty” pavement thickness requirement for similar projects.

We believe that the ESAL values of 20,000 and 73,000 should be considered to classify as Light

Duty and Heavy Duty pavement sections, respectively. The Heavy Duty pavement section should be constructed in locations of heavy vehicular traffic movements such as truck routes.

If estimated daily traffic volumes for the facility are known to be different from those assumed, we should be provided with this information in order to reevaluate the pavement sections provided below.

Pavement Thickness Requirements: Alternatives for flexible pavements of full-depth hot mix asphalt (HMA) or a composite section of HMA over aggregate base course (ABC), and rigid pavements of Portland cement concrete (PCC) are presented in the table below. The pavement sections were determined in accordance with the 1993 AASHTO pavement design procedures.

For design purposes, a reliability of 75% was assumed for all pavement areas. The following table presents the minimum pavement thickness alternatives for the project:

LOCATION

Asphalt Thickness

(inches)

Asphalt Over Aggregate Base

Course (inches)

Concrete Thickness (inches)

Light Duty 4 3 over 6 5 Heavy Duty 5.5 4 over 6 7

Truck loading dock areas and other areas where truck turning movements are concentrated should be paved with 7 inches of Portland cement concrete. The concrete pavement should contain sawed or formed control joints to ¼ of the depth of the slab at a maximum distance of

12 feet on center. Concrete pavements may be a suitable alternative for parking lots and delivery areas.

Pavement Materials: The following are recommended material and placement requirements for pavement construction for this project site. We recommend that properties and mix designs for all materials proposed to be used for pavements be submitted for review to the geotechnical engineer prior to placement.

Aggregate Base Course: Aggregate base course (ABC) used beneath HMA pavements should meet the material specifications for Grading GR or L stated in the current

WYDOT “Standard Specifications for Road and Bridge Construction”. The ABC should be placed and compacted as outlined in the “SITE GRADING” section of this report.

Hot Mix Asphalt: Hot mix asphalt (HMA) materials and mix designs should meet the applicable requirements indicated in the current WYDOT “Standard Specifications for

Road and Bridge Construction”. We recommend that the HMA used for this project is designed in accordance with the SuperPave gyratory mix design method. The mix should meet Class II-S specifications with a SuperPave gyratory design revolution

(NDESIGN) of 75 and a maximum nominal aggregate size of ¾” or ½”. The mix design(s) for the HMA should use a performance grade asphalt binder (PGAB) of 58-28 or 64-22. However, we recommend the PGAB 58-28 binder which tends to perform better under relatively low traffic volumes. Placement and compaction of HMA should follow current WYDOT standards and specifications.

Portland Cement Concrete: Portland Cement Concrete (PCC) pavement should meet

Class P specifications and requirements in the current WYDOT “Standard Specifications for Road and Bridge Construction”. Rigid PCC pavements are more sensitive to distress due to movement resulting from settlement or heave of the underlying base layer and/or subgrade than flexible asphalt pavements. The PCC pavement should contain sawed or formed joints to ¼ of the depth of the slab at a maximum distance of 12 to 15 feet on center.

The above PCC pavement thicknesses are presented as un-reinforced slabs. Based on projects with similar vehicular loading in certain areas, we recommend that dowels be provided at transverse and longitudinal joints within the slabs located in the travel lanes of heavily loaded vehicles, loading docks and areas where truck turning movements are likely to be concentrated. Additionally, curbs and/or pans should be tied to the slabs.

The dowels and tie bars will help minimize the risk for differential movements between slabs to assist in more uniformly transferring axle loads to the subgrade. The proper sealing and maintenance of joints to minimize the infiltration of surface water is critical to the performance of PCC pavement, especially if dowels and tie bars are not installed.

Subgrade Preparation: Fill materials exist across this site and will be the predominant subgrade material available on-site. The fill should be evaluated by proof-rolling the surface and by performing in-place moisture/density tests both at and 1 foot below pavement subgrade elevation. If the stability is adequate based on proof-rolling, and the moisture/density tests indicate the existing fill generally meets the moisture content and compaction requirements indicated in this report, the fill may be left in place. If either the stability based on proof-rolling or in-place moisture/density tests indicate the fill as unsuitable, the fill will need to be reworked to provide a suitable and stable subgrade for overlying pavements.

If the fill is found to be suitable, the upper 8 inches should be scarified, adjusted in moisture content and compacted as indicated in the Site Grading section of this report. If the fill is found to be unsuitable, the upper 2 feet should be removed and the exposed surface scarified to a depth of 12 inches. The scarified materials should be adjusted in moisture content and compacted as indicated in the Site Grading section of this report. The subgrade should be brought to final plan elevation using materials meeting the criteria and placed as indicated in the

Site Grading section of this report.

Pavement design procedures assume a stable subgrade and the pavement subgrade should be proof-rolled, preferably within 48 hours prior to paving. The proof-roll should be performed using a heavily loaded pneumatic-tired vehicle such as a loaded water truck or large front-end loader. Areas that deform under wheel loads that are not stable should be removed and replaced to achieve a stable subgrade prior to paving.

Drainage: The collection and diversion of surface drainage away from paved areas is extremely important to the satisfactory performance of pavement. Drainage design should provide for the removal of water from paved areas and prevent the wetting of the subgrade soils.

DESIGN AND CONSTRUCTION SUPPORT SERVICES

Kumar & Associates, Inc. should be retained to review the project plans and specifications for conformance with the recommendations provided in our report. We are also available to assist the design team in preparing specifications for geotechnical aspects of the project, and performing additional studies if necessary to accommodate possible changes in the proposed

We recommend that Kumar & Associates, Inc. be retained to provide observation and testing services to document that the intent of this report and the requirements of the plans and specifications are being followed during construction, and to identify possible variations in subsurface conditions from those encountered in this study so that we can re-evaluate our recommendations, if needed.

LIMITATIONS

This study has been conducted in accordance with generally accepted geotechnical engineering practices in this area for exclusive use by the client for design purposes. The conclusions and recommendations submitted in this report are based upon data obtained from the exploratory borings at the locations indicated on Fig. 1, and the proposed construction. This report may not reflect subsurface variations that occur between the explorations, and the nature and extent of variations across the site may not become evident until site grading and excavations are performed. If during construction, fill, soil, rock or groundwater conditions appear to be different from those described herein, Kumar & Associates, Inc. should be advised at once so that a re-evaluation of the recommendations presented in this report can be made. Kumar & Associates, Inc. is not responsible for liability associated with interpretation of subsurface data by others.

The recommendations presented in this report are based on current theories and experience of our engineers on the behavior of swelling soil in this area. The owner should be aware that there is risk of movement and possible damage to foundations, interior slab-on-grade floors, and exterior slabs and pavements on sites where expansive soils and/or bedrock occur. Following the recommendations given by a geotechnical engineer, careful construction practice and prudent maintenance by the owner can, however, decrease this risk.

JAH/es cc: Book, file

Project No.: 17-3-207 Project Name: Saratoga Bunkhouse Date Sampled: November 20, 2017 Date Received: November 20, 2017

Boring Depth (Feet) Gravel

(%) Sand (%) Liquid

Limit (%) Plasticity

1 4 11/28/17 2.6 34 58 8 NV NP A-1-b (0) Poorly Graded Sand with Silt and Gravel (SP-SM) 1 9 11/28/17 2.3 34 52 14 NV NP A-1-b (0) Silty Sand with Gravel (SM) 1 19 11/28/17 17.0 110.0 Sandstone Bedrock 2 4 11/28/17 12.5 114.4 16 41 43 29 12 0.00 A-6 (2) Clayey Sand with Gravel (SC)

Table I

Sample Location Gradation Atterberg Limits

Date Tested

Natural Moisture Content

Natural Dry

Density (pcf)

Percent Passing No. 200 Sieve

Water Soluble Sulfates

AASHTO

Classification (Group

Index) Soil or Bedrock Type

Summary of Laboratory Test Results