GEO-TECH_REPORT_OTOE_PROJECT_(4_19_2021)_0001.pdf

REPORT OF SUBSURFACE EXPLORATION

AND GEOTECHNICAL EVALUATION

PROPOSED OTOE MISSOURIA TRIBE

PAVEMENT IMPROVEMENTS

RED ROCK, OKLAHOMA

BUILDING & EARTH PROJECT NO.: OK210050

PREPARED FOR:

RK & Associates, PLC

APRIL 19, 2021

1403 South 70th East Avenue

Tulsa, OK 74112 Tel: (918) 439-9005 www.BuildingAndEarth.com

Birmingham, AL Auburn, AL Huntsville, AL Montgomery, AL Tuscaloosa, AL Columbus, GA Louisville, KY Raleigh, NC Dunn, NC

Jacksonville, NC Springdale, AR Little Rock, AR Ft. Smith, AR Tulsa, OK Oklahoma City, OK Nashville, TN DFW Metroplex, TX Virginia Beach, VA

4/19/2021

April 19, 2021

RK & Associates, PLC 4815 South Harvard Avenue, Suite 290 Tulsa, Oklahoma 74135

Attention: Mr. Rick Kosman, P.E.

Subject: Report of Subsurface Exploration and Geotechnical Evaluation

Proposed OTOE Missouria Tribe Pavement Improvements Red Rock, Oklahoma

Building & Earth Project No: OK210050

Dear Mr. Kosman:

Building & Earth Sciences, Inc. has completed the authorized subsurface exploration and geotechnical engineering evaluation for the Proposed OTOE Missouria Tribe Pavement Improvements at the OTOE Missouria Tribe campus in Red Rock, Oklahoma.

The purpose of this exploration and evaluation was to determine general subsurface conditions at the site and to address applicable geotechnical aspects of the proposed pavement improvements. The recommendations in this report are based on a physical reconnaissance of the site and observation and classification of samples obtained from nineteen (19) test borings conducted at the site. Confirmation of the anticipated subsurface conditions during construction is an essential part of geotechnical services.

We appreciate the opportunity to provide consultation services for the proposed project. If you have any questions regarding the information in this report or need any additional information, please call us.

Respectfully Submitted, BUILDING & EARTH SCIENCES, INC.

Certificate of Authorization, #3975, Expires 6/30/2022

Spencer Harris Marco V. Vicente Silvestre, P.G., P.E.

Field Professional II Regional Vice President

OK: 21903

http://www.buildingandearth.com/

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Table of Contents

1.0 PROJECT & SITE DESCRIPTION

2.0 SCOPE OF SERVICES

3.0 GEOTECHNICAL SITE CHARACTERIZATION

3.1 EXISTING SURFACE CONDITIONS

3.2 SUBSURFACE CONDITIONS

GROUNDWATER

4.0 SITE DEVELOPMENT CONSIDERATIONS

4.1 INITIAL SITE PREPARATION

4.2 MOISTURE SENSITIVE SOILS

4.3 PAVEMENT SUBGRADE PREPARATION

UNDERCUTTING LOW CONSISTENCY/UNSTABLE SOILS

UNDERCUTTING HIGH PLASTICITY CLAYS

SUBGRADE PREPARATION AND EVALUATION

4.4 STRUCTURAL FILL

STRUCTURAL FILL PLACEMENT

4.5 EXCAVATION CONSIDERATIONS

PERCHED GROUNDWATER

4.6 UTILITY TRENCH BACKFILL

4.7 LANDSCAPING AND DRAINAGE CONSIDERATION

4.8 WET WEATHER CONSTRUCTION

5.0 PAVEMENT CONSIDERATIONS

5.1 FLEXIBLE PAVEMENT

5.2 RIGID PAVEMENT

6.0 SUBGRADE REHABILITATION

7.0 CONSTRUCTION MONITORING

8.0 CLOSING AND LIMITATIONS

APPENDIX

Subsurface Exploration and Geotechnical Evaluation, Proposed OTOE Missouria Tribe Pavement Improvements, Red Rock, OK Project No: OK210050, April 19, 2021

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1.0 PROJECT & SITE DESCRIPTION

The subject site is located at the Missouria Tribe campus in Red Rock, Oklahoma. The campus includes numerous buildings and associated pavements. Google Earth satellite imagery of the overall site is provided below in Figure 1.

Figure 1: Google Earth image of site with planned pavement improvement areas

The areas where proposed improvements were investigated are broken down in the Google Earth imageries below. The proposed improvements to each subject area, as provided by RK & Associates, are described in Table 1 below.

Figure 2: Project Area ‘A’ Figure 3: Project Area ‘B’

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Figure 4: Project Area ‘C’ Figure 5: Project Area ‘D’

Figure 6: Project Area ‘E’ Figure 7: Project Area ‘F’

Figure 8: Project Area ‘G’

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Parking Area General Planned Improvements Associated Borings

Project Area ‘A’ Wellness Center New Parking Lot

A new circle drive to the north, and a new parking lot along with a new concrete sidewalk abutting the east side of the center. The parking lot shall provide for 24 parking stalls with a concrete apron for a trash container on south end.

P-01 through P-04

Project Area ‘B’ Existing Parking Lot, south of Otoe

Seniors

Reconstruction of parking lot which has very wide cracking across the asphalt pavement P-05 and P-06

Project Area ‘C’ Existing Parking Lot, north of

Learning Center, south of Tribal Council and west of Maintenance Shops

Reconstruction of parking lot needing drainage improvements at the west side of the Learning Center (Dead End Driveway) and at the northwest corner of the overall parking lot east of the Maintenance Shops. Construction may include a swale from the south end of the dead-end driveway and possibly a new concrete swale northward from the ponding area across the secondary entrance to the Maintenance Shops to drain storm water northerly. Curb and gutter appear in good condition and probably will remain in most places.

P-07 through P-10

Project Area ‘D’ Existing Parking Lot, west of the

Enterprise Center and west of the Education Center

Reconstruction of parking lot using concrete pavement to be tied to match to the surrounding concrete pavement.

P-11 through P-13

Project Area ‘E’ & ‘F’ Existing Parking Lot, east of the

Enterprise Center, southeast of the Education Center, and southeast of the Tribal Center

Reconstruction of the overall parking lot will include driveway to the Maintenance Shops. Minor drainage improvement is needed at intersection of main roadway and driveway. Probably a concrete section, including a concrete swale southward to the culvert under the driveway to the Learning Center parking lot. Reconstruction may include new curb and guttering with new sidewalks in front of the north and west buildings and new handicap ramps. New PVC conduits may be recommended at various locations for future electric or signage.

P-14 though P-17

Project Area ‘G’ Existing Parking Lot, Health Services

Reconstruction of this parking lot shall include new bumper blocks and concrete pad for trash container.

P-18 and P-19

Table1: Proposed Improvements for each subject area Notes:

1. A grading plan was not available at the time of preparing this report. We assume that most reconstruction areas remain close to grade with minor adjustments (i.e., less than 1 foot) for drainage improvements on as needed basis. When a grading plan is finalized, Building & Earth should be allowed to review the plan and its effects on our recommendations.

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Photographs depicting the current site conditions at each subject area are presented on the following pages. Minor to severe separation within the existing asphalt pavement was observed throughout the entire site.

Figure 9: Project Area ‘A’ Figure 10: Project Area ‘B’

Figure 11: Project Area ‘C’ Figure 12: Project Area ‘D’

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Figure 13: Project Area ‘E’ Figure 14: Project Area ‘F’

Figure 15: Project Area ‘G’

2.0 SCOPE OF SERVICES

The authorized subsurface exploration was performed on March 15, 2021 in conformance with our proposal OK22316, dated March 3, 2021. Notice to proceed was provided by signing our contract on March 3, 2021.

The purpose of the geotechnical exploration was to determine general subsurface conditions at specific boring locations and to gather data on which to base a geotechnical evaluation with respect to the proposed pavement improvements. The subsurface exploration for this project consisted of nineteen (19) test borings.

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All borings were drilled with a Diedrich D-50 track mounted drill rig equipped with solid flight augers and a manual hammer.

The boring locations were determined in the field by a representative of our staff using a handheld GPS device. As such, the boring locations shown on the Boring Location Plan attached to this report should be considered approximate.

The soil samples recovered during our site exploration were visually classified and specific samples were selected by the project engineer for laboratory analysis. The laboratory analysis consisted of:

Test ASTM No. of Tests

Natural Moisture Content D2216 64

Atterberg Limits D4318 11

Material Finer Than No. 200 Sieve by Washing D1140 4 Table 2: Scope of Laboratory Tests

The results of the laboratory analysis are presented on the enclosed Boring Logs and in tabular form in the Appendix of this report. Descriptions of the laboratory tests that were performed are also included in the Appendix.

The information gathered from the exploration was evaluated to determine if any special subgrade preparation procedures will be required during the earthwork phase of the project and to establish minimum pavement sections for planned improvements.

The results of the work are presented within this report that addresses:

Summary of existing surface conditions.

A description of the subsurface conditions encountered at the boring locations.

A description of the groundwater conditions observed in the boreholes during drilling. Long-term monitoring was not included in our scope of work.

Presentation of laboratory test results.

Site preparation considerations including material types to be expected at the site, treatment of any encountered unsuitable soils, excavation considerations, and surface drainage.

Compaction requirements and recommended criteria to establish suitable material for structural backfill.

Recommended typical minimum flexible and rigid pavement sections based on assumed traffic loading conditions.

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3.0 GEOTECHNICAL SITE CHARACTERIZATION

The following discussion is intended to create a general understanding of the site from a geotechnical engineering perspective. It is not intended to be a discussion covering all the potential geotechnical issues that may arise, nor to provide every possible interpretation of the conditions identified. The following conditions and subsequent recommendations assume that significant changes in subsurface conditions do not occur between boreholes. However, anomalous conditions can occur due to variations in existing fill or the geologic conditions at the site, and it will be necessary to evaluate the assumed conditions during subgrade preparation and pavement reconstruction.

3.1 EXISTING SURFACE CONDITIONS

At the time of our subsurface exploration, the project site was covered with mostly asphalt pavement, except for project area ‘A’, which was gravel and grass covered. The topsoil encountered in boring P-04 was approximately 4 inches thick. The topsoil conditions reported apply only to the specific boring locations. It should be noted that topsoil thicknesses likely vary at unexplored locations of the project site. For this report, topsoil is defined as the soil horizon which contains the root mat of the noted vegetation.

3.2 SUBSURFACE CONDITIONS

A generalized stratification summary has been prepared using data from the test borings and is presented in the table below. The stratification depicts the general soil conditions and strata encountered during our field investigation.

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Stratum No.

Typical Thickness Description Consistency Lab Testing Data (4)

1(1) 0.6’ to 4.1’

Fill Material: Lean clays and sandy lean clays with some fat clay, sandstone and limestone fragments, ferrous staining and nodules, and trace coal fragments

Various shades of brown, reddish brown, and gray

In general, stiff to very stiff except for boring P-14, with medium stiff material

Atterberg Limits:

LL = 42, PI = 24

Moisture Content Range:

14 to 23%

2 (2) 2’ to 6.5’

Residuum: Lean clay, sandy lean clay, and fat clay (3) with trace fine roots, limestone and sandstone fragments, ferrous staining and nodules, calcium deposits, and few wet pockets

Various shades of brown, reddish brown, grayish brown, and gray

Typically, stiff to very stiff

Soft to medium stiff in the top 2.5 ft (3)

Atterberg Limits LL=27 to 51, PI=10 to 35

Moisture Content Range:

12 to 25%

% Passing #200 Sieve:

86 to 91%

Table 3: Stratification Summary Table 3 Notes:

(1) Encountered in borings P-06 through P-11, P-14, P-16, and P-19 only.

(2) All borings terminated within the residual clay stratum.

(3) Encountered in borings P-02, P-04, P-13, P-14, and P-18 only.

(4) For Atterberg Limits: LL = Liquid Limit, PL = Plastic Limit, and PI = Plasticity Index

For specific details on information obtained from individual borings, refer to the Boring Logs included in the Appendix. The ground surface elevations at the boring locations indicated in this report were obtained by a professional surveyor and shared by RK & Associates, PLC.

GROUNDWATER

Groundwater seepage was encountered during drilling of boring P-19 at a depth of about

3.9 feet. The other borings were dry during drilling and they remained dry at the time of backfilling.

Fluctuations in the water level can occur due to seasonal rainfall. Water levels are accurate only for the time and date that the borings were drilled. Long term monitoring of the boreholes was not included as part of our subsurface exploration. The borings were backfilled the same day that they were drilled.

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4.0 SITE DEVELOPMENT CONSIDERATIONS

A grading plan was not available at the time of preparing this report. We assume that most reconstruction areas remain close to grade with minor adjustments (i.e., less than 1 foot) for drainage improvements on as needed basis. When a grading plan is finalized, Building & Earth should be allowed to review the plan and its effects on our recommendations.

The primary geotechnical concerns for this project are:

◾ Area ‘A’: near-surface lower consistency soils with relatively high moisture contents were encountered in grass covered areas, extending to depths of about 2 to 2.5 ft.

◾ Area ‘B’: high plasticity residual fat clays and fill comprised of higher plasticity clays were encountered below the full-depth asphaltic concrete pavements.

◾ Area ‘C’: existing fill materials with thickness ranging from roughly 0.5 to 1.5 feet were encountered below the full-depth asphaltic concrete pavements. High plasticity fat clays were encountered in one of the four borings.

◾ Area ‘D’: most of the subgrade encountered below the full-depth asphaltic concrete comprised of stiff, medium plasticity lean clays. One boring encountered minor amount of existing fill, and another boring encountered medium stiff clays below the pavement.

◾ Area ‘E’: existing fill and very soft residual lean clay was encountered below the full-depth asphaltic concrete pavement to a depth of approximately 2.5 feet.

◾ Area ‘F’: with exception of boring P-16, stiff residual lean clays were encountered below the pavement. In boring P-16, soft clay fill extended to depth of about 2.5 feet below top of pavement.

◾ Area ‘G’: medium stiff clay fill was encountered to depth of about 4.5 feet in boring P-19. Groundwater seepage was encountered in that same boring at depth of approximately 3.9 feet, which appeared to be perched within the fill at the contact with stiff residuum.

Recommendations addressing the site conditions are presented in the following sections.

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4.1 INITIAL SITE PREPARATION

All vegetation, roots, topsoil, and any other deleterious materials, should be removed from the proposed construction areas. Approximately 4 inches of topsoil was observed in boring P-04 only; however, topsoil could extend to greater depths in unexplored areas of the site. For this report, topsoil is defined as the horizon which contains most of the root mat of the noted vegetation.

Existing pavements materials are to be removed from the proposed reconstruction areas.

Existing utility lines are anticipated within parts of the pavement reconstruction areas. The backfill of utility trenches need to be carefully evaluated to determine they comprise of properly compacted and suitable material for support of proposed new pavement sections. Any unsuitable backfill material needs to be removed and replaced with approved structural fill.

Materials disturbed during clearing operations should be undercut to undisturbed materials and backfilled with properly compacted, approved structural fill. A geotechnical engineer should observe stripping and demolition operations to evaluate that all unsuitable materials are removed from locations for proposed construction.

During site preparation activities, the contractor should identify borrow source materials that will be used as structural fill and provide samples to the testing laboratory so that conformance to the Structural Fill requirements outlined below and appropriate moisture-density relationship curves can be determined.

4.2 MOISTURE SENSITIVE SOILS

The lower plasticity lean clay soils are moisture sensitive, prone to losing strength and stability with slight increases in soil moisture contents and when subjected to repeat traffic loads. These soils likely will degrade when saturated. Therefore, not allowing water to pond by maintaining positive drainage and temporary dewatering methods (if required) is important to help avoid degradation and softening of the soils.

The contractor should anticipate difficulty during the earthwork phase of this project when moisture levels are moderate to high during construction. Increased moisture levels will soften the subgrade and the soils will be unstable under the influence of construction traffic.

4.3 PAVEMENT SUBGRADE PREPARATION

Pavement subgrade preparation is area specific and a summary for each area can be found in the following table.

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Parking Area Pavement Subgrade Preparation

Project Area ‘A’ Wellness Center New

Parking Lot

Following removal of existing aggregate (borings P-01 and P-03), the exposed subgrade is to be evaluated and prepared in accordance with Section 4.3.3.

Lower consistency, low plasticity lean clays are anticipated in areas outside of the existing aggregate covered areas. Anticipate the need for undercutting soft and unstable soils to depth of approximately 1.5 feet below existing subgrade following the recommendation outlined in Section 4.3.1.

Project Area ‘B’ Existing Parking Lot, south of Otoe Seniors

High plasticity residual fat clays and existing fill materials are anticipated at finished subgrade. These materials have a high shrink-swell potential with poor pavement subgrade support properties. It is recommended to partially undercut higher plasticity clays to a level that will allow for placement of at least 12 inches of approved, lower plasticity structural fill following the recommendations presented in Section 4.3.2.

Project Area ‘C’ Existing Parking Lot, north of Learning Center, south of Tribal

Council and west of Maintenance Shops

Following removal of existing pavements, the exposed subgrade is to be evaluated and prepared in accordance with Section 4.3.3.

Project Area ‘D’ Existing Parking Lot, west of the Enterprise Center and west of the

Education Center

Following removal of existing pavements, the exposed subgrade is to be evaluated and prepared in accordance with Section 4.3.3. Lower consistency soils were encountered to depth of about 2.5 feet in boring P-13. Anticipate areas with the need for undercutting unstable soils following the recommendation outlined in Section 4.3.1.

Project Area ‘E’ & ‘F’ Existing Parking Lot, east of the Enterprise Center, southeast of the Education Center, and southeast of the

Tribal Center

For the proposed improvement to the drive leading to the maintenance facility (Project Area ‘E’), expect soft and unstable subgrade materials. Anticipate the need for undercutting soft and unstable soils to depth of approximately 2 feet below existing subgrade following the recommendation outlined in Section 4.3.1.

For the proposed improvement to the parking lot east of the Enterprise Center, southeast of the Education Center, and southeast of the Tribal Center (Project Area ‘F’), proof roll existing subgrade. Expect soft/unstable subgrade materials to depth of approximately 2.5 feet in the area of boring P-16.

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Parking Area Pavement Subgrade Preparation

Project Area ‘G’ Existing Parking Lot, Health Services

Following removal of existing pavements, the exposed subgrade is to be evaluated and prepared in accordance with Section 4.3.3. Lower consistency clay fill was encountered to depth of about 4.5 feet in boring P-19. Anticipate areas with the need for undercutting unstable soils following the recommendation outlined in Section 4.3.1.

UNDERCUTTING LOW CONSISTENCY/UNSTABLE SOILS

Following pavement demolition and any cuts needed to accommodate design grades, low consistency and/or unstable soils are anticipated to be exposed across portions of proposed pavement areas. Soft/unstable soils do not provide a suitable subgrade for fill placement or support of proposed new pavements.

Depending on depth of soft/unstable soils, the following can be considered to provide for a stable subgrade that is suitable for supporting new pavement sections:

Soft/unstable soils extending to depth of 12 inches can be scarified, moisture conditioned, and recompacted as outlined in Section 4.3.3 of this report.

Soft/unstable soils extending to depths of 12 to 24 inches should be undercut 12 inches and the spoils stockpiled for reuse when they meet the structural criteria outlined in the Structural Fill section of this report. The remaining in-place soft/unstable soils then can be scarified, moisture conditioned, and recompacted as outlined in Section 4.3.3 of this report.

For areas requiring undercut depths greater than 24 inches, it may be more practical and cost effective to mechanically stabilize the subgrade using an ODOT Type 2 geogrid and graded crushed aggregate, such as ODOT Type “A” aggregate.

Detailed stabilization recommendations can be developed at the time of construction, depending on the subgrade conditions encountered in the specific area at that time.

Undercut areas are to be brought back up to design grades using approved structural fill.

The placement procedure, compaction and composition of the structural fill must meet the requirements of the Structural Fill section of this report.

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UNDERCUTTING HIGH PLASTICITY CLAYS

High plasticity clay soils, i.e., fat clays (CH), have a high swell potential and they typically provide poor support for pavement sections. Post-construction moisture absorption will result in swelling of the clays and subsequent heave of overlying pavement, and development of tension cracks.

As such, we recommend that all fat clays (CH) be undercut to a level that will allow placement of at least 12 inches of structural fill.

Prior to start of fill placement, the exposed cut subgrade is to be scarified, moisture conditioned, and recompacted as outlined in Section 4.3.3 of this report.

SUBGRADE PREPARATION AND EVALUATION

Prior to fill placement, the exposed clay subgrade within the proposed pavement areas should be scarified, moisture conditioned, and recompacted to a minimum depth of 8 inches. Subgrade soils comprised of lean clays (CL) should be moisture conditioned within a range of 2 percent below to 2 percent above the material’s optimum moisture content.

Subgrade soils comprised of fat clays (CH) should be moisture conditioned within a range of 0 to 3 percent above the material’s optimum moisture content. All subgrade soils are to be recompacted to least 95 percent of the material’s standard Proctor maximum dry density.

We recommend that the project geotechnical engineer or their qualified representative evaluate the subgrade after the site is prepared. Some unsuitable or unstable areas may be present in unexplored areas of the site. All areas that will require fill or that will support pavements should be carefully proofrolled with a fully loaded, tandem-axle dump truck (20- to 25-ton), at the following times.

◾ After an area has been stripped, and undercut as anticipated and recommended, prior to the placement of any fill.

◾ After grading an area to the finished subgrade elevation in pavement area.

◾ After areas have been exposed to any precipitation, and/or have been exposed for more than 48 hours.

All soft and unstable soils identified during the proofrolling process must be undercut or stabilized prior to fill placement or pavement construction. All unsuitable material identified during the construction shall be removed and replaced in accordance with the Structural Fill section of this report.

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4.4 STRUCTURAL FILL

Requirements for imported structural fill on this project are as follows:

Soil Type USCS

Classification Property Requirements Placement Location

Imported Lean Clay, Clayey

Sand or Shale

CL, SC

LL<40, 7<PI<20,

γd>100 pcf, P200>15%, Maximum 3” particle size in any dimension, CBR ≥ 3.0

Low Plasticity Structural Fill to be used for construction of pavement subgrade

Onsite Lean Clays CL

Same as for Imported Structural Fill above

Suitable for use as lower plasticity structural fill in pavement areas

Onsite Lean to Fat Clays and Fat Clays CL-CH, CH Not Applicable

Not suitable for use as lower plasticity structural fill due to higher plasticity characteristics

Table 5: Structural Fill Requirements

Notes:

1. Structural fill should be free of vegetation, topsoil, and any other deleterious materials. The organic content of materials to be used for fill should be less than 3 percent.

2. LL indicates the soil Liquid Limit; PI indicates the soil Plasticity Index; P200 indicates the percent of material by weight that passes the #200 sieve; γd indicates the maximum dry density as defined by the density standard outlined in the table below.

3. Laboratory testing of the soils proposed for fill must be performed to verify their conformance with the above recommendations.

4. Any fill to be placed at the site should be reviewed by the geotechnical engineer.

5. Some of the onsite clay soils had relatively high moisture contents at the time of our subsurface exploration. When considering the use of these soils for structural fill, the contractor should anticipate the need for drying of the soils prior to placement. Double handling of materials and drying of soils using windrowing techniques should be expected.

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STRUCTURAL FILL PLACEMENT

Placement requirements for structural fill are as follows:

Specification Requirement

Lift Thickness Maximum loose lift thickness of 8 to 12 inches, depending on type of compaction equipment used.

Density 95% of the standard Proctor (ASTM D698) maximum density

Moisture ±2% of the optimum moisture content as determined by ASTM D698

Density Testing Frequency Pavement area: One test per 5,000 SF per lift with a minimum of three tests performed per lift Utility trenches: One test per 150 linear feet per lift

Table 6: Structural Fill Placement Requirements

4.5 EXCAVATION CONSIDERATIONS

All excavations performed at the site should follow OSHA guidelines for temporary excavations. Excavated soils should be stockpiled according to OSHA regulations to limit the potential cave-in of soils.

PERCHED GROUNDWATER

Perched water was encountered in the fill at the contact with underlying stiff residuum at depth of about 3.9 feet in boring P-19.

The other borings were dry at the time of the subsurface exploration. Although groundwater seepage was not encountered in other borings, elevated moisture contents were noted for some of the samples collected immediately below the pavement or near the contact with underlying less permeable soils.

There is a probability for development of perched water, particularly at the interface of the lower plasticity clay soils and underlying higher plasticity clay soils. Perched water may be encountered in undercut areas and in utility trenches.

It should be noted that fluctuations in the water level could occur due to seasonal variations in rainfall. The contractor must be prepared to remove groundwater seepage from excavations if encountered during construction. Excavations extending below groundwater levels will require dewatering systems (such as sump pumps or trench drains). The contractor should evaluate the most economical and practical dewatering method based on the conditions encountered during construction.

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4.6 UTILITY TRENCH BACKFILL

All utility trenches must be backfilled and compacted in the manner specified above for structural fill. It may be necessary to reduce the lift thickness to 4 to 6 inches to achieve compaction using hand-operated equipment.

4.7 LANDSCAPING AND DRAINAGE CONSIDERATION

The potential for soil moisture fluctuations within pavement subgrades should be reduced to lessen the potential of subgrade movement. Site grading should include positive drainage away from pavements areas. Excessive irrigation of landscaping poses a risk of saturating soils below pavements, which could result in premature failure of pavements.

4.8 WET WEATHER CONSTRUCTION

Excessive movement of construction equipment across the site during wet weather may result in ruts, which will collect rainwater, prolonging the time required to dry the subgrade soils.

During rainy periods, additional effort will be required to properly prepare the site and establish/maintain an acceptable subgrade. The difficulty will increase in areas where clay or silty soils are exposed at the subgrade elevation. Grading contractors typically postpone grading operations during wet weather to wait for conditions that are more favorable. Contractors can typically disk or aerate the upper soils to promote drying during intermittent periods of favorable weather. When deadlines restrict postponement of grading operations, additional measures such as undercutting and replacing saturated soils or stabilization can be utilized to facilitate placement of additional fill material.

5.0 PAVEMENT CONSIDERATIONS

Specific traffic information was not provided at the time of this report. For this report, we assumed that standard-duty parking lots will be subjected to passenger cars, pick-up trucks, and occasional light box trucks (i.e., UPS and FedEx trucks). Medium duty drive aisles within parking lots are expected to be subjected to traffic that is similar to standard-duty pavements. Heavy-duty pavements comprise of access drives and parking areas that will be subjected to frequent maintenance vehicles, and occasional delivery truck and trash collection truck traffic.

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Based on the materials encountered at the boring locations and after our recommendations for site preparation are implemented, flexible pavements at the subject site may be designed based on an estimated California Bearing Ratio (CBR) of 3. Note that no CBR or plate load testing was completed to develop these recommendations. In addition, we have assumed the following design parameters:

Design Criteria Value

Design life (Years) 20

Terminal Serviceability 2.0

Reliability 85%

Initial Serviceability 4.2 (Flexible), 4.5 (Rigid)

Standard Deviation 0.45(Flexible), 0.35(Rigid)

Table 7: Assumed Design Parameters

All subgrade, base and pavement construction operations should meet minimum requirements of the Oklahoma Department of Transportation (ODOT), Standard Specifications for Highway Construction, dated 2019. The applicable sections of the specifications are identified as follows:

Material Specification Section

Portland Cement Concrete Pavement 414 & 701

Plant Mix Asphalt Concrete Pavement 411 & 708

Mineral Aggregate Base Materials 303 & 703.01

Table 8: ODOT Specification Sections

5.1 FLEXIBLE PAVEMENT

The asphalt pavement sections described herein were designed using the “AASHTO Guide for Design of Pavement Structures, 1993”. Alternative pavement sections were designed by establishing the structural numbers used for the AASHTO design system and substituting materials based upon structural equivalency as follows:

Material Structural No.

Asphalt Concrete 0.44

Crushed Aggregate Base (ODOT Type “A”) 0.14

Table 9: Structural Equivalent Coefficient

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The following typical minimum flexible pavement sections are based on the design parameters presented above:

Minimum Recommended Thickness (in) Material Standard

Duty Medium

Duty Heavy Duty

Parking Stalls

Drives Aisles in Parking

Access Drives

2.0 2.0 2.0 HMAC Surface Course (Superpave “S4”)

2.5 3.5 3.5 HMAC Binder Course (Superpave “S3”)

6.0 6.0 12.0 Crushed Aggregate Base (ODOT Type “A”)

Table 10: Asphalt Pavement Recommendations

In accordance with the ODOT specifications, asphaltic concrete should be compacted within 92 to 97 percent of the theoretical maximum specific gravity of the asphaltic concrete mix. The underlying aggregate base course should be compacted to at least 98 percent of the material’s standard Proctor maximum dry density with a moisture content range of ± 2 percent of the optimum moisture content at the time of placement.

5.2 RIGID PAVEMENT

The following rigid pavement sections are based on the design parameters presented above. We assume an effective modulus of subgrade reaction (k) of 100 pci. We have assumed concrete elastic modulus (Ec) of 3.1 X 106 psi, and a concrete modulus of rupture (S’c) of 600 psi.

Minimum Recommended Thickness (in) Material

Standard Duty Heavy Duty Parking Stalls and Drive Aisles

Access Drives

5.0 6.0 Portland Cement Concrete, f’c=3,500 psi

4.0 6.0 Crushed Aggregate Base (ODOT Type “A”)

Table 11: Rigid Pavement Recommendations

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For access drive approaches, trash compactor pads, loading areas, and other pavement areas that are frequently subject to high traffic loads with frequent braking and turning of wheels, consideration should be given to using a rigid pavement section comprised of seven (7) inches of Portland cement concrete over six (6) inches of crushed aggregate base course.

The concrete should be protected against moisture loss, rapid temperature fluctuations, and construction traffic for several days after placement. All pavements should be sloped for positive drainage. We suggest that a curing compound be applied after the concrete has been finished.

Although not referenced in the ODOT specifications, based on our experience with project sites in this region and anticipated traffic loads, we recommend Portland cement concrete should have a minimum 28-day compressive strength of 3,500 psi, maximum slump of 4 inches, and air content of 5 to 7 percent.

For rigid pavements, we recommend a jointing plan be developed to control cracking and help preclude surficial migration of water into the base course and subgrade. If a jointing plan includes a widely spaced pattern (spacing typically greater than 30 times the slab thickness), consideration should be given to include steel reinforcement in rigid pavements, per Section 3.4 of the American Association of State Highway and Transportation Officials (AASHTO) Guide for Design of Pavement Structures 1993, and Section 3.8 of the American Concrete Institute (ACI) Guide for the Design and Construction of Concrete Parking Lots. Additionally, we recommend the joints be sealed to further preclude surficial moisture migration into the underlying supporting soils.

All pavements should be sloped, approximately ¼ inch per foot, to provide rapid surface drainage. Water allowed to pond on or adjacent to the pavement could saturate the subgrade and cause premature deterioration of the pavements because of loss of strength and stability. Periodic maintenance of the pavement should be anticipated. This should include sealing of cracks and joints and maintaining proper surface drainage to avoid ponding of water on or near the pavement areas.

6.0 SUBGRADE REHABILITATION

The subgrade soils often become disturbed during the period between initial site grading and construction of surface improvements. The amount and depth of disturbance will vary with soil type, weather conditions, construction traffic, and drainage.

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The engineer should evaluate the subgrade soil during final grading to verify that the subgrade is suitable to receive pavement and/or concrete slab base materials. The final evaluation may include proofrolling or density tests.

Subgrade rehabilitation can become a point of controversy when different contractors are responsible for site grading and building construction. The construction documents should specifically state which contractor will be responsible for maintaining and rehabilitating the subgrade. Rehabilitation may include moisture conditioning and re-compacting soils. When deadlines or weather restrict grading operations, additional measures such as undercutting and replacing saturated soils or chemical stabilization can often be utilized.

7.0 CONSTRUCTION MONITORING

Field verification of site conditions is an essential part of the services provided by the geotechnical consultant. To confirm our recommendations, it will be necessary for Building & Earth personnel to make periodic visits to the site during site grading. Typical construction monitoring services are listed below.

◾ Periodic observations and consultations by a member of our engineering staff during site grading

◾ Field density tests during structural fill and aggregate base course placement

◾ Molding and testing of concrete cylinders

◾ Sampling of asphalt for mix verification and coring for determination of in-place thickness and density

8.0 CLOSING AND LIMITATIONS

This report was prepared for RK & Associates for specific application to the pavement improvements at the campus of the and the OTEO Missouria Tribe in Red Rock, Oklahoma.

The information in this report is not transferable. This report should not be used for a different development on the same property without first being evaluated by the engineer.

The recommendations in this report were based on the information obtained from our field exploration and laboratory analysis. The data collected is representative of the locations tested. Variations are likely to occur at other locations throughout the site.

Engineering judgment was applied regarding conditions between borings. It will be necessary to confirm the anticipated subsurface conditions during construction.

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This report has been prepared in accordance with generally accepted standards of geotechnical engineering practice. No other warranty is expressed or implied. If changes are made, or anticipated to be made, to the nature, design, or location of the project as outlined in this report, Building & Earth must be informed of the changes and given the opportunity to either verify or modify the conclusions of this report in writing, or the recommendations of this report will no longer be valid.

The scope of services for this project did not include any environmental assessment of the site or identification of pollutants or hazardous materials or conditions. If the owner is concerned about environmental issues Building & Earth would be happy to provide an additional scope of services to address those concerns.

This report is intended for use during design and preparation of specifications and may not address all conditions at the site during construction. Contractors reviewing this information should acknowledge that this document is for design information only.

An article published by the Geoprofessional Business Association (GBA), titled Important Information About Your Geotechnical Report, has been included in the Appendix. We encourage all individuals to become familiar with the article to help manage risk.

Appendix Table of Contents

GEOTECHNICAL INVESTIGATION METHODOLOGIES

DRILLING PROCEDURES – STANDARD PENETRATION TEST (ASTM D1586)

BORING LOG DESCRIPTION

DEPTH AND ELEVATION

SAMPLE TYPE

SAMPLE NUMBER

BLOWS PER INCREMENT, REC%, RQD%

SOIL DATA

SOIL DESCRIPTION

GRAPHIC

REMARKS

SOIL CLASSIFICATION METHODOLOGY

KEY TO LOGS

KEY TO HATCHES

BORING LOCATION PLAN

BORING LOGS

LABORATORY TEST PROCEDURES

DESCRIPTION OF SOILS (VISUAL-MANUAL PROCEDURE) (ASTM D2488)

NATURAL MOISTURE CONTENT (ASTM D2216)

ATTERBERG LIMITS (ASTM D4318)

MATERIAL FINER THAN NO. 200 SIEVE BY WASHING (ASTM D1140)

LABORATORY TEST RESULTS

IMPORTANT INFORMATION ABOUT THIS GEOTECHNICAL-ENGINEERING REPORT

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GEOTECHNICAL INVESTIGATION METHODOLOGIES

The subsurface exploration, which is the basis of the recommendations of this report, has been performed in accordance with industry standards. Detailed methodologies employed in the investigation are presented in the following sections.

DRILLING PROCEDURES – STANDARD PENETRATION TEST (ASTM D1586)

At each boring location, soil samples were obtained at standard sampling intervals with a split-spoon sampler. The borehole was first advanced to the sample depth by augering and the sampling tools were placed in the open hole. The sampler was then driven 18 inches into the ground with a 140-pound automatic hammer free-falling 30 inches. The number of blows required to drive the sampler each 6-inch increment was recorded. The initial increment is considered the “seating” blows, where the sampler penetrates loose or disturbed soil in the bottom of the borehole.

The blows required to penetrate the final two (2) increments are added together and are referred to as the Standard Penetration Test (SPT) N-value. The N-value, when properly evaluated, gives an indication of the soil’s strength and ability to support structural loads.

Many factors can affect the SPT N-value, so this result cannot be used exclusively to evaluate soil conditions.

The SPT testing was performed using a drill rig equipped with an automatic hammer.

Automatic hammers mechanically control the height of the hammer drop, and doing so, deliver higher energy efficiency (90 to 99 % efficiency) than manual hammers (60 % efficiency) which are dropped using a manually operated rope and cathead system. Because historic data correlations were developed based on use of a manual hammer, it is necessary to adjust the N-values obtained using an automatic hammer to make these correlations valid. Therefore, an energy correction factor of 1.3 was applied to the recorded field N-values from the automatic hammer for the purpose of our evaluation. The N-values discussed or mentioned in this report and shown on the boring logs are recorded field values.

Samples retrieved from the boring locations were labeled and stored in plastic bags at the jobsite before being transported to our laboratory for analysis. The project engineer prepared Boring Logs summarizing the subsurface conditions at the boring locations.

BORING LOG DESCRIPTION

Building & Earth Sciences, Inc. used the gINT software program to prepare the attached boring logs. The gINT program provides the flexibility to custom design the boring logs to include the pertinent information from the subsurface exploration and results of our laboratory analysis. The soil and laboratory information included on our logs is summarized below:

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DEPTH AND ELEVATION

The depth below the ground surface and the corresponding elevation are shown in the first two columns.

SAMPLE TYPE

The method used to collect the sample is shown. The typical sampling methods include Split Spoon Sampling, Shelby Tube Sampling, Grab Samples, and Rock Core. A key is provided at the bottom of the log showing the graphic symbol for each sample type.

SAMPLE NUMBER

Each sample collected is numbered sequentially.

BLOWS PER INCREMENT, REC%, RQD%

When Standard Split Spoon sampling is used, the blows required to drive the sampler each 6-inch increment are recorded and shown in column 5. When rock core is obtained the recovery ration (REC%) and Rock Quality Designation (RQD%) is recorded.

SOIL DATA

Column 6 is a graphic representation of four different soil parameters. Each of the parameters use the same graph, however, the values of the graph subdivisions vary with each parameter.

Each parameter presented on column 6 is summarized below:

• N-value- The Standard Penetration Test N-value, obtained by adding the number of blows required to drive the sampler the final 12 inches, is recorded . The graph labels range from 0 to 50.

• Qu – Unconfined Compressive Strength estimate from the Pocket Penetrometer test in tons per square foot (tsf). The graph labels range from 0 to 5 tsf.

• Atterberg Limits – The Atterberg Limits are plotted with the plastic limit to the left, and liquid limit to the right, connected by a horizontal line. The difference in the plastic and liquid limits is referred to as the Plasticity Index. The Atterberg Limits test results are also included in the Remarks column on the far right of the boring log. The Atterberg Limits graph labels range from 0 to 100%.

• Moisture – The Natural Moisture Content of the soil sample as determined in our laboratory.

SOIL DESCRIPTION

The soil description prepared in accordance with ASTM D2488, Visual Description of Soil Samples. The Munsel Color chart is used to determine the soil color. Strata changes are indicated by a solid line, with the depth of the change indicated on the left side of the line and the elevation of the change indicated on the right side of the line. If subtle changes within a soil type occur, a broken line is used. The Boring Termination or Auger Refusal depth is shown as a solid line at the bottom of the boring.

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GRAPHIC

The graphic representation of the soil type is shown. The graphic used for each soil type is related to the Unified Soil Classification chart. A chart showing the graphic associated with each soil classification is included.

REMARKS

Remarks regarding borehole observations, and additional information regarding the laboratory results and groundwater observations.

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SOIL CLASSIFICATION METHODOLOGY

Major Divisions Symbols

Group Name & Typical Description Lithology Group

Coarse Grained

Soils

More than 50% of material is larger than

No. 200 sieve size

Gravel and Gravelly coarse fraction is larger than No. 4 sieve

Clean Gravels

(Less than 5% fines)

GW Well-graded gravels, gravel – sand mixtures, little or no fines

GP

Poorly-graded gravels, gravel – sand mixtures, little or no fines

Gravels with Fines

(More than 12% fines)

GM Silty gravels, gravel – sand – silt mixtures

GC Clayey gravels, gravel – sand – clay mixtures

Sand and Sandy coarse fraction is smaller than

No. 4 sieve

Clean Sands

(Less than 5% fines)

SW Well-graded sands, gravelly sands, little or no fines

SP

Poorly-graded sands, gravelly sands, little or no fines

Sands with Fines

(More than 12% fines)

SM Silty sands, sand – silt mixtures

SC Clayey sands, sand – clay mixtures

Fine Grained material is smaller than No. 200 sieve size

Silts and Clays

Liquid Limit less than 50

Inorganic

ML

Inorganic silts and very find sands, rock flour, silty or clayey fine sands or clayey silt with slight plasticity

CL

Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays

Organic

OL Organic silts and organic silty clays of low plasticity

Silts and Clays

Liquid Limit greater than

Inorganic

MH

Inorganic silts, micaceous or diatomaceous fine sand, or silty soils

CH Inorganic clays of high plasticity

Organic

OH

Organic clays of medium to high plasticity, organic silts

Highly Organic Soils

PT

Peat, humus, swamp soils with high organic contents

Table 1: Soil Classification Chart (based on ASTM D2487)

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SOIL CLASSIFICATION METHODOLOGY

* - Modified based on 80% hammer efficiency

Building & Earth Sciences classifies soil in general accordance with the Unified Soil Classification System (USCS) presented in ASTM D2487. Table 1 and Figure 1 exemplify the general guidance of the USCS. Soil consistencies and relative densities are presented in general accordance with Terzaghi, Peck, & Mesri’s (1996) method, as shown on Table 2, when quantitative field and/or laboratory data is available. Table 2 includes Consistency and Relative Density correlations with N-values obtained using either a manual hammer (60 percent efficiency) or automatic hammer (90 percent efficiency). The Blows Per Increment and SPT N-values displayed on the boring logs are the unaltered values measured in the field. When field and/or laboratory data is not available, we may classify soil in general accordance with the Visual Manual Procedure presented in ASTM D2488.

Non-cohesive: Coarse-Grained Soil Cohesive: Fine-Grained Soil

SPT Penetration (blows/foot) Relative

Density

SPT Penetration (blows/foot)

Consistency

Estimated Range of Unconfined Compressive

Strength (tsf)

Automatic Hammer*

Manual Hammer

Automatic Hammer*

Manual Hammer < 2 < 2 Very Soft < 0.25

0 - 3 0 - 4 Very Loose 2 - 3 2 - 4 Soft 0.25 – 0.50

3 - 8 4 - 10 Loose 3 - 6 4 - 8 Medium Stiff 0.50 – 1.00

8 - 23 10 - 30 Medium Dense 6 - 12 8 - 15 Stiff 1.00 – 2.00

23 - 38 30 - 50 Dense 12 - 23 15 - 30 Very Stiff 2.00 – 4.00

> 38 > 50 Very Dense > 23 > 30 Hard > 4.00

Table 2: Soil Consistency and Relative Density (based on Terzaghi, Peck & Mesri, 1996)

0 10 20 30 40 50 60 70 80 90 100 Pl as tic ity In de x

(P I)

Liquid Limit (LL)

CH or OH

MH or OH

CL or OL

ML or OLCL-ML7

Figure 1: Plasticity Chart (based on ASTM D2487)

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KEY TO LOGS

Standard Penetration Test ASTM D1586 or

AASHTO T-206

Dynamic Cone Penetrometer (Sower DCP)

ASTM STP-399

Soil Particle Size U.S. Standard

Boulders Larger than 300 mm N.A.

Cobbles 300 mm to 75 mm N.A.

Shelby Tube Sampler

ASTM D1587

No Sample Recovery

Gravel 75 mm to 4.75 mm 3-inch to #4 sieve

Coarse 75 mm to 19 mm 3-inch to ¾-inch sieve

Fine 19 mm to 4.75 mm ¾-inch to #4 sieve

Rock Core Sample

ASTM D2113

Groundwater at Time of Drilling

Sand 4.75 mm to 0.075 mm #4 to #200 Sieve

Coarse 4.75 mm to 2 mm #4 to #10 Sieve

Medium 2 mm to 0.425 mm #10 to #40 Sieve

Auger Cuttings

Groundwater as Indicated

Fine 0.425 mm to 0.075 mm #40 to #200 Sieve

Fines Less than 0.075 mm Passing #200 Sieve

Silt Less than 5 µm N.A.

Clay Less than 2 µm N.A.

Table 1: Symbol Legend Table 2: Standard Sieve Sizes

Standard Penetration Test Resistance calculated using ASTM D1586 or AASHTO T-

206. Calculated as sum of original, field recorded values.

A measure of a soil’s plasticity characteristics in general accordance with ASTM D4318. The soil Plasticity Index (PI) is representative of this characteristic and is bracketed by the Liquid Limit (LL) and the Plastic Limit (PL).

Unconfined compressive strength, typically estimated from a pocket penetrometer. Results are presented in tons per square foot (tsf).

Percent natural moisture content in general accordance with ASTM D2216.

Table 3: Soil Data

Hollow Stem Auger Flights on the outside of the shaft advance soil cuttings to the surface. The hollow stem allows sampling through the middle of the auger flights.

Descriptor

Meaning Mud Rotary /

Wash Bore A cutting head advances…