Geotech Report - Wichita.pdf

REPORT COVER PAGE

Geotechnical Engineering Report

Building 60 Addition at Robert J. Dole VA Medical Center Wichita, Kansas

May 24, 2021 Terracon Project No. 01215004

Prepared for:

H2B Inc.

Tempe, AZ

Prepared by:

Terracon Consultants, Inc.

Wichita, Kansas

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REPORT TOPICS

INTRODUCTION

SITE CONDITIONS

PROJECT DESCRIPTION

GEOTECHNICAL CHARACTERIZATION

GEOTECHNICAL OVERVIEW

EARTHWORK

SHALLOW FOUNDATIONS

FLOOR SLABS

PAVEMENTS

GENERAL COMMENTS

FIGURES

ATTACHMENTS

Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section and clicking on the GeoReport logo will bring you back to this page. For more interactive features, please view your project online at client.terracon.com.

ATTACHMENTS

EXPLORATION AND TESTING PROCEDURES

SITE LOCATION AND EXPLORATION PLANS

EXPLORATION RESULTS

SUPPORTING INFORMATION

Note: Refer to each individual Attachment for a listing of contents.

http://client.terracon.com/

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INTRODUC TION

Geotechnical Engineering Report Building 60 Addition at Robert J. Dole VA Medical Center

5500 E Kellogg Ave Wichita, Kansas

Terracon Project No. 01215004 May 24, 2021

INTRODUCTION

This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed Building 60 addition at Robert J. Dole VA Medical Center to be located at 5500 E Kellogg Ave in Wichita, Kansas. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

■ Subsurface soil conditions ■ Floor slab design and construction

■ Site preparation and earthwork ■ Pavement design and construction

■ Foundation design and construction

The geotechnical engineering Scope of Services for this project included the advancement of seven test borings to depths ranging from approximately 5 to 15 feet below existing site grades.

Maps showing the site and boring locations are shown in the Site Location and Exploration Plan sections, respectively. The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included on the boring logs and/or as separate graphs in the Exploration Results section.

SITE CONDITIONS

The following description of site conditions is derived from our site visit in association with the field exploration and our review of publicly available geologic and topographic maps.

Item Description Parcel Information The building addition is located at 5500 E Kellogg Ave in Wichita, Kansas.

Current Ground Cover Primarily grass surfaced or paved with some sidewalks, patios, and trees Existing Topography Relatively level

Building 60 Addition at Robert J. Dole VA Medical Center ■ Wichita, Kansas May 24, 2021 ■ Terracon Project No. 01215004

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PROJECT DESCRIPTION

Our initial understanding of the project was provided in our proposal and was discussed during project planning. A period of collaboration has transpired since the project was initiated, and our final understanding of the project conditions is as follows:

Item Description

Information Provided Email provided by Mr. Roderick Grier with H2B Inc.

Project Description

The project will include the construction of these structures

■ Building 60 addition will be a single story, slab-on-grade structure with a footprint of about 15,000 ft2. An approximately 10,000 ft2 Meditation Garden is also planned.

Maximum Loads

■ Columns: 30 kips (provided by H2B Inc.)

■ Walls (Building 60): 3 klf (estimated by Terracon)

■ Slabs: 150 psf (estimated by Terracon)

Grading We anticipate that cuts/fills of less than 2 feet will be required to achieve final grades.

Pavements Paved driveways and parking

GEOTECHNICAL CHARACTERIZATION

We have developed a general characterization of the subsurface conditions based upon our review of the subsurface exploration, laboratory data, geologic setting and our understanding of the project. This characterization, termed GeoModel, forms the basis of our geotechnical calculations and evaluation of site preparation and foundation options. Conditions encountered at each exploration point are indicated on the individual logs. The individual logs can be found in the Exploration Results section and the GeoModel can be found in the Figures section of this report.

As part of our analyses, we identified the following model layers within the subsurface profile. For a more detailed view of the model layer depths at each boring location, refer to the GeoModel.

Model Layer Layer Name General Description

1 Fill: Fat Clay, Lean Clay, Lean to Fat Clay, Sandy Lean Clay With sand in some areas

2 Lean Clay, Lean to Fat Clay Stiff to medium stiff 3 Shale Highly weathered cameron.crockett Callout

THIS IS WAY UNDERESTIMATED...

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Groundwater Conditions

The boreholes were observed while drilling and after completion for the presence and level of groundwater. Groundwater was not observed in our borings while drilling, or for the short duration the borings could remain open.

Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater could develop during the life of the structure. Long term observations in piezometers or observation wells sealed from the influence of surface water are often required to define groundwater levels. Also, it is possible that groundwater could temporarily perch seasonally at shallow depths. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project.

GEOTECHNICAL OVERVIEW

Based on the information obtained from our subsurface exploration, it is our opinion that the site can be developed for the proposed project. The Earthwork section addresses site preparation and compaction. The Shallow Foundations section addresses support of the building addition bearing on engineered fill or native stiff clays. The Floor Slabs section addresses slab-on-grade support of the building addition. The Pavements section addresses subgrade preparation and provides typical pavement thicknesses based on estimated traffic information. The General Comments section provides an understanding of the report limitations.

Existing fill materials were found to depths of up to about 2 to 6 feet below existing site grades at our boring locations. Fill should be expected to occur (possibly to a greater depth) in other areas across the sites. We are not aware that the existing fill has been placed with moisture and density control.

Foundations and floor slabs supported on or above existing uncontrolled fill material that has not been uniformly placed and compacted with strict moisture and density control may not perform predictably. We consider the existing fill in its current condition to be unsuitable to support the proposed building addition. The depth and composition of the existing fill materials can vary greatly over relatively small lateral and vertical distances. Because of this variability, it may not be possible (until site grading is underway) to accurately predict the amount of fill that will need to be removed and replaced to develop suitable support for the proposed improvements. Caution should be exercised when using the depth and composition of the fill observed at the discrete boring locations, for estimating purposes.

Most of the fill observed in our borings appears suitable for re-use as new controlled fill below the recommended Low Volume Change (LVC) zone, provided it is properly moisture conditioned and compacted. However, the fill could contain unobserved materials that would render it unsuitable for re-use as new controlled fill. We encourage the owner to secure a base bid for removing and cameron.crockett Highlight

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Moderately to highly expansive soils are present on this site. This report provides recommendations to help mitigate the effects of soil shrinkage and expansion. However, even if these procedures are followed, some movement and cracking in the structure should be anticipated. The severity of cracking and other damage such as uneven floor slabs will probably increase if any modification of the site results in excessive wetting or drying of the expansive soils. Eliminating the risk of movement and distress may not be feasible, but it may be possible to further reduce the risk of movement if significantly more expensive measures are used during construction. Some of these options could include increasing the thickness of the recommended low volume change zone and/or constructing a structural slab. We would be pleased to discuss other construction alternatives with you upon request.

The owner or contractor could consider a contingency budget to provide for additional earthwork items such as moisture conditioning dry subgrade soils, repairing soft subgrade soils, and removing unsuitable foundation bearing soils.

EARTHWORK

Earthwork is anticipated to include clearing and grubbing, excavations, and fill placement. The following sections provide recommendations for use in the preparation of specifications for the work. Recommendations include critical quality criteria, as necessary, to render the site in the state considered in our geotechnical engineering evaluation for foundations and floor slabs.

Site Preparation

We recommend all pavement, and utilities from the proposed building addition area. Also, we recommend removing all existing fill from within and at least 5 feet beyond the building addition area presently proposed for construction.

After completing these operations and any cuts needed to develop design grade the exposed subgrade be thoroughly proofrolled (under the observation of Terracon personnel) with a loaded tandem-axle dump truck or other heavy, rubber-tired construction equipment weighing at least 20 tons, to locate any zones that are soft or unstable. The subgrade in the building addition area where excessive rutting or pumping occurs during proofrolling should be removed and replaced or aerated/reworked and recompacted in place to our recommendations for engineered fill (see below for details) prior to placement of areal fill.

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INCOMPLETE SENTENCE, DID THEY MEAN REMOVE?

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Fill Material Types Engineered fill should meet the following material property requirements:

Soil Type 1 USCS Classification Acceptable Parameters (for Structural Fill)

Lean Clay 2 CL 3

(LL<46 & PI>15)

> 18 inches below building addition finished subgrade

Lean to Fat Clay 2 CL/CH 3

(46≤LL<50)

> 18 inches below building addition finished subgrade

Fat Clay 2 CH

(LL≥50)

> 18 inches below building addition finished subgrade

Well-graded granular and silty gravel

GM-GW

GM 4 All locations and elevations

Low Volume Change

Material (LVC) 5

CL or GM-GW, GM 4 and

(LL<40 & 5≤PI<15)

All locations and elevations

On-Site Soils Varies

The on-site soils, free of organic matter and debris, typically appear suitable for reuse as engineered fill. However, these near surface soils do not meet the low volume change zone criteria and should not be utilized within 18 inches of finished subgrade beneath the proposed building addition.

1. Controlled, compacted fill should consist of approved materials that are free of organic matter and debris.

Frozen material should not be used, and fill should not be placed on a frozen subgrade. A sample of each material type should be submitted to the geotechnical engineer for evaluation.

2. Delineation of fat clays and lean clays should be performed in the field by a qualified geotechnical engineer or their representative and could require additional laboratory testing.

3. By our definition, cohesive soils with a liquid limit of 46 to 49 are classified as lean to fat clay (with the borderline symbol CL/CH) to alert of the expansive potential of clay soils with liquid limits close to 50 (see ASTM D2487-11, Section 1.1, Note 1).

4. Similar to KDOT AB-3 crushed limestone aggregate, limestone screenings, or granular material such as sand, gravel or crushed stone containing at least 15% low plasticity fines (-#200).

5. Low volume change cohesive soil or granular soil having at least 15% low plasticity fines (-#200).

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THIS TABLE IS VERY SIMILAR TO THE ONE IN THE B26 REPORT. THE TABLE HAS BEEN CREATED IN THE REVIT MODEL AND CAN BE IMPORTED FROM THERE.

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Fill Compaction Requirements

Structural fill should meet the following compaction requirements.

Item Structural Fill

Lift Thickness

9-inches or less in loose thickness when heavy, self-propelled compaction equipment is used or 4 to 6 inches in loose thickness when hand-guided equipment (jumping jack or plate compactor) is use

Compaction Requirements 1

Below Footing Bearing Level:

At least 97% of the material’s maximum standard Proctor dry density (ASTM D698).

Above Footing Bearing Level: At least 95%, but not more than 100%, of the material’s maximum standard Proctor dry density (ASTM D698).

Pavement: The final 8 inches of the subgrade in the pavement areas should be compacted to at least 98% of the material’s maximum standard Proctor dry density (ASTM D698). Below the final 8 inches of the subgrade in the pavement areas the fill should be compacted to at least 95% of the material’s maximum standard Proctor dry density (ASTM D698).

Moisture Content Cohesive Soils with PI of 35 and higher

At least 3 percentage points above the optimum moisture content value as determined by the standard Proctor test at the time of placement and compaction

Moisture Content Cohesive Soils with PI of 25 to 34

At least 2 percentage points above the optimum moisture content value as determined by the standard Proctor test at the time of placement and compaction

Moisture Content Cohesive Soils with PI of 18 to 24

Above the optimum moisture content value as determined by the standard Proctor test at the time of placement and compaction

Moisture Content Cohesive Soils with PI less than 18

No drier than 2 percentage points below the optimum moisture content value as determined by the standard Proctor test at the time of placement and compaction

Moisture Content Granular Material 2 Workable moisture levels

1. We recommend the moisture content and compaction be determined for each lift of engineered fill during placement. Should the results of the in-place density tests indicate the specified moisture or compaction limits have not been met, the area represented by the test should be reworked and retested as required until the specified moisture and compaction requirements are achieved. The zone of fill compacted to meet these criteria should extend at least 5 feet and 2 feet horizontally beyond the building addition footprint and pavement areas, respectively.

2. Specifically, moisture levels should be maintained low enough to allow for satisfactory compaction to be achieved without the cohesionless fill material pumping.

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Grading and Drainage

All grades must provide effective drainage away from the building addition during and after construction and should be maintained throughout the life of the structure. Water retained next to the building addition can result in soil movements greater than those discussed in this report.

Greater movements can result in unacceptable differential floor slab and/or foundation movements, cracked slabs and walls, and roof leaks. The roof should have gutters/drains with downspouts that discharge onto pavement or splash blocks at a distance of at least 10 feet from the building addition.

Exposed ground should be sloped and maintained at a minimum 5% away from the building addition for at least 10 feet beyond the perimeter of the building addition. Locally, flatter grades may be necessary to transition ADA access requirements for flatwork. After building addition construction and landscaping have been completed, final grades should be verified to document effective drainage has been achieved. Grades around the structure should also be periodically inspected and adjusted, as necessary, as part of the structure’s maintenance program. Where paving or flatwork abuts the structure, a maintenance program should be established to effectively seal and maintain joints and prevent surface water infiltration.

Earthwork Construction Considerations

It is anticipated that excavations for the proposed construction can be accomplished with conventional earthmoving equipment. These soils could become unstable with typical earthwork and construction traffic, especially after precipitation events. Upon completion of filling and grading, care should be taken to maintain the subgrade moisture content prior to construction of floor slabs. Construction traffic over the completed subgrade should be avoided to the extent practical. The site should also be graded to prevent ponding of surface water on the prepared subgrade or in excavations. If the subgrade should become frozen, desiccated, saturated, or disturbed, the affected material should be removed, or these materials should be scarified, moisture conditioned, and recompacted prior to floor slab and pavement construction and observed by Terracon.

Surface water should not be allowed to pond on the site and soak into the soil during construction.

Construction staging should provide drainage of surface water and precipitation away from the building addition area. Any water that collects over or adjacent to construction areas should be promptly removed, along with any softened or disturbed soils. Surface water control in the form of sloping surfaces, drainage ditches and trenches, and sump pits and pumps will be important to avoid ponding and associated delays due to precipitation and seepage.

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Based on our understanding of the proposed building addition, we do not expect groundwater to adversely affect construction. If groundwater is encountered during construction, some form of temporary or permanent dewatering may be required. Conventional dewatering methods, such as pumping from sumps, should likely be adequate for temporary removal of any groundwater encountered during excavation at the site.

As a minimum, excavations should be performed in accordance with OSHA 29 CFR, Part 1926, Subpart P, “Excavations” and its appendices, and in accordance with any applicable local, state, and federal safety regulations. The contractor should be aware that slope height, slope inclination, and excavation depth should in no instance exceed those specified by these safety regulations. Flatter slopes than those dictated by these regulations may be required depending upon the soil conditions encountered and other external factors. These regulations are strictly enforced and if they are not followed, the owner, contractor, and/or earthwork and utility subcontractor could be liable and subject to substantial penalties.

Construction site safety is the sole responsibility of the contractor who controls the means, methods, and sequencing of construction operations. Under no circumstances shall the information provided herein be interpreted to mean Terracon is assuming responsibility for construction site safety, or the contractor's activities; such responsibility shall neither be implied nor inferred.

Fill Construction Observation and Testing

The earthwork efforts should be monitored by Terracon. Monitoring should include documentation of adequate removal of vegetation and topsoil, proofrolling, and mitigation of areas delineated by the proofroll to require mitigation.

The exposed subgrade and each lift of compacted fill should be tested, evaluated, and reworked, as necessary, until approved by the geotechnical engineer’s representative prior to placement of additional lifts. We recommend that each lift of fill be tested for density and moisture content at a frequency of at least one test for every 2,500 square feet of compacted fill in the building and pavement areas. We recommend at least one density and moisture content test for every 50 linear feet of compacted utility trench backfill.

SHALLOW FOUNDATIONS

In our opinion, the proposed building addition can be supported by a shallow, spread footing foundation system bearing on newly constructed compacted structural fill prepared in accordance with the requirements noted in the Earthwork section of this report or suitable native materials consisting of stiff clays. Design recommendations for shallow foundations are presented in the following paragraphs.

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Design Recommendations and Parameters

Item Column Continuous

Net Allowable Bearing pressure 1 on newly constructed compacted structural fill 2 and/or suitable native materials consisting of stiff clays or highly weathered shale

2,500 psf 2,500 psf

Minimum footing width 30 inches 12 inches (trenched) 16 inches (formed)

Minimum embedment below finished grade for frost protection 3 42 inches 42 inches

Estimated Total Settlement 4 <1 inch <1 inch

Estimated Differential Settlement 4 <¾ inch between columns <¾ inch over 40 feet

1. The recommended net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation. Assumes any unsuitable fill or soft soils, if encountered, will be undercut and replaced with engineered fill.

2. All new engineered fill beneath footings should be constructed as recommended in Fill Compaction Requirements of the Earthwork section of this report.

3. And to reduce the effects of seasonal moisture variations in the subgrade soils. For perimeter footings and footings beneath unheated areas.

4. The foundation settlement will depend upon the variations within the subsurface soil profile, the structural loading conditions, the embedment depth of the footings, the thickness of compacted fill, and the quality of the earthwork operations. The above settlement estimates have assumed that the maximum loads stated previously in the Project Description section of this report will not be exceeded.

Foundation Construction Considerations

The footing excavations should be evaluated under the direction of the Terracon Geotechnical Engineer. The base of all foundation excavations should be free of water and loose soil, prior to placing concrete. Concrete should be placed soon after excavating to reduce bearing soil disturbance. Care should be taken to prevent wetting or drying of the bearing materials during construction. Should the soils at bearing level become excessively dry, disturbed or saturated, or frozen, the affected soil should be removed prior to placing concrete. Consider placing a lean concrete mud-mat over the bearing soils if the excavations must remain open over night or for an extended time.

cameron.crockett Rectangle cameron.crockett Text Box 30" SQ = 15 k 36" SQ = 22 k 42" SQ = 30 k 48" SQ = 40 k 54" SQ = 50 k 60" SQ = 62 k 72" SQ = 90 k 84" SQ = 122 k 96" SQ = 160 k cameron.crockett Highlight cameron.crockett

THIS IS WAY UNDERESTIMATED...

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Regarding construction of footings, we generally anticipate that material suitable for support of the design bearing pressure will be present at the base of the footings. However, there is a possibility that isolated zones of soft native soils or low density fill or could be encountered below footing bearing level, even though field density tests are expected to be performed during fill placement operations. Therefore, we recommend that the geotechnical engineer of record be retained to observe, test, and evaluate the soil foundation bearing prior to placing reinforcing steel and concrete to determine if additional footing excavation depth is needed.

If unsuitable bearing soils are encountered in footing excavations, the excavations should be extended deeper to suitable soils and the footings could bear directly on these soils at the lower level or on lean concrete backfill placed in the excavations. As an alternative an overexcavation and backfill procedure could be utilized wherein the foundation could bear on properly compacted backfill extending down to suitable soils. The overexcavation for compacted backfill placement should extend laterally beyond the edges of the footing in all directions at least 8 inches per foot of overexcavation depth below design bearing level. The overexcavation should then be backfilled up to the footing base elevation with approved well-graded granular material constructed as described in section Compaction Requirements of the Earthwork section of this report.

Care should be taken during construction not to disturb the soils beneath the existing foundations.

Some overlap of stresses between the new and existing footings will occur if the two foundation systems abut each other possibly causing some movement of the existing footings and supported structure. To reduce this overlap of stresses between the new and existing footings we recommend maintaining a clear distance between the edge of the new and existing footings at least equal to one-half the width of the new footings. Connections between the new and existing structures should accommodate some movement between the addition and adjoining existing building.

FLOOR SLABS

Building Pad Subgrade Preparation

In addition to providing a subgrade suitable from a strength perspective as addressed in the Earthwork section of this report, a factor affecting floor slab performance is the potential for the subgrade soils to shrink/swell due to variations in moisture content. Typically, some increase in the floor slab subgrade moisture content will occur because of gradual accumulation of capillary moisture, which would otherwise evaporate if the floor slab had not been constructed. A soil’s swell potential is dependent primarily on its plasticity, and moisture content. The confining pressure provided by the weight of the floor slab and the overburden pressure (including the fill required to develop design grade) also effect swell potential. Subgrade soils with higher plasticity and lower moisture content and confining pressure, generally have greater swell potential.

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The near-surface fill soils encountered in our borings have medium to high plasticity and were generally in a relatively moist condition at the time of our subsurface exploration. Based on a method of analyses that uses Atterberg limits values, total unit weight, and our experience with similar soils, we estimated a potential vertical rise (PVR) greater than 1 inch for these soils. In our opinion, this amount of potential vertical rise could cause excessive heave of floor slabs. This potential to swell could increase if further drying occurs prior to, or during, construction. To reduce the swell potential to a relatively small amount, less than about one inch, we recommend that at least the upper 18 inches of subgrade soils below the floor slab be low volume change (LVC) material that we describe in detail in Fill Material Types of the Earthwork section of this report.

Because we expect that the high plasticity clay materials could have greater swell potential if they are drier at the start of construction than they were at the time the borings were performed, constructing a 18-inch thick LVC zone may not be adequate to limit floor slab heave to a small amount. Therefore, we recommend that Terracon evaluate the material within at least 36 inches of the bottom of the LVC zone just prior to placement of any additional fill (see Building Subgrade Preparation Diagram below). Where the existing materials within this depth range at the start of construction are drier than the minimum moisture requirements stated in Fill Compaction Requirements of the Earthwork section of this report, we recommend corrective procedures be implemented. These procedures would include over-excavating if dry soils are present and either uniformly increasing their moisture content to the minimum moisture contents stated in Fill Compaction Requirements of the Earthwork section of this report and reworking/recompacting the soil in lifts or replacing them with LVC material. If LVC material is used to replace the dried soils, it should be placed at the moisture content values described in Fill Compaction Requirements of the Earthwork section of this report.

Note: Presently the near surface soils are typically relatively moist. Also, remove and replace unsuitable materials including uncontrolled existing fill that may extend to greater depths than shown in the above diagrams.

DRY SUBGRADE CONDITION MOIST SUBGRADE CONDITION

Finished Floor Elevation Finished Floor Elevation Finished Subgrade Elevation Finished Subgrade Elevation

Concrete Floor Slab Concrete Floor Slab Granular Capillary Cutoff/Leveling Course Granular Capillary Cutoff/Leveling Course

18 Inches LOW VOLUME CHANGE (LVC) Material LOW VOLUME CHANGE (LVC) Material (see report for details) 18 Inches (see report for details)

24 Inches

Low Volume Change (LVC) Material Or 6 Inches Subgrade: Scarify, Moisture-Condition, And

54 Inches Reworked Native Clays Compact In Place 30 Inches (See Report For Recommended

Moisture and Density)

30 Inches If The Evaluation Indicates That These Soils

6 Inches Subgrade: Scarify, Moisture-Condition, And Are Sufficiently Moist, Then Moisture- Compact In Place -Conditioning Of These Soils Is Not Required

BUILDING SUBGRADE PREPARATION DIAGRAM (NOT TO SCALE)

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Prior to placing additional areal fill where moisture conditioning (as described above) is not needed, we recommend the upper 6 inches of exposed subgrade be scarified and recompacted to the compaction requirements and at the moisture contents stated in Fill Compaction Requirements in the Earthwork section of this report.

Low Volume Change Zone

As stated previously, we recommend the upper 18 inches of material directly below the floor slabs be LVC material. This is primarily to help protect the newly placed fill from moisture fluctuations during construction and provide a layer of soil that will not experience significant volume change as the moisture content fluctuates.

By our definition, LVC materials have a liquid limit (LL) less than 40 and a plasticity index (PI) of at least 5, but less than 15. LVC materials that meet this requirement may include granular soils (such as limestone/concrete screenings or clayey sand) or possibly silty, sandy or lean clays, although laboratory testing of prospective LVC materials proposed for use by the contractor should be conducted to confirm their suitability prior to bidding/construction. Cohesive LVC soils may need extensive “wetting maintenance” by the contractor to maintain the required above optimum moisture content in the cohesive LVC material until construction of the floors. Based on the soils encountered in the borings, the near-surface fat clays do not meet the criteria for LVC material.

If cohesive material meeting the above criteria cannot be readily obtained, an LVC soil may be developed with the clay overburden soils by modifying them with hydrated lime, Class C fly ash, cement/cement slurry, or possibly Cement Kiln Dust (CKD) although using the dry agents may result in objectionable dusting problems. A lime slurry or cement slurry application (or the use of granular LVC materials) would reduce the dusting problems. It has been our experience that some CKD products have excessively high sulfate contents that would react adversely when mixed with soils, causing undesirable swell and heave. When CKD is considered, we recommend that a recent chemical laboratory analysis is submitted to us for review prior to approval of the CKD product. Because of the potentially deleterious heave that could result if hydrated lime is used to modify shale or soil that contains sulfates, such as gypsum zones or seams, we recommend that shale or overlying soil above the shale not be modified with hydrated lime unless extensive additional laboratory and field testing is performed to determine if excessive sulfates are present and if they would react adversely with the hydrated lime.

For clay materials, it has been our experience that hydrated lime contents of 4% to 6%, cement/cement slurry contents of 5% to 6%, CKD contents of 6% to 8%, or Class C fly ash contents of 14% to 16, based on the dry weight of the soil, would typically be required to appreciably reduce the shrink/swell characteristics of clayey soils not meeting the previously described plasticity requirements for LVC materials. A more precise application rate should be developed based on additional laboratory testing. Recognized guidelines such as those specified by KDOT or City of Wichita (including minimum mixing temperatures) should be followed during

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Responsive ■ Resourceful ■ Reliable 13 the mixing and construction of the fly ash- or lime-modified subgrade. A lime/cement slurry application or the use of a granular LVC material may reduce the dusting problems that could occur with subgrade modification using dry products. The modified zone should extend at least 3 feet beyond the edges of the proposed building. Soils mixed with Class C fly ash should be compacted within 2 hours following blending operations.

The LVC soils should be placed in lifts not exceeding 9 inches in loose thickness and compacted to at least 95%, but not more than 100%, of maximum dry density. Cohesive soils should be placed and maintained at moisture contents not less than 2 percentage points below their optimum moisture content. Granular soils should be placed at workable moisture content. If lime-or fly ash-modified soils are used, they should be placed and maintained at moisture contents above their optimum moisture content.

Cohesive LVC materials can be swell susceptible if allowed to dry before constructing the floor slab; therefore, it is important that the recommended moisture content of the cohesive LVC material be maintained. As a check, we recommend the subgrade moisture content be evaluated about 3 to 4 days before placing concrete. If drying of the subgrade materials has occurred at this time, measures should be taken to increase the moisture content of the subgrade soils before placing the sand leveling course or concrete, which may also include recompaction. If the subgrade was modified with fly ash and recompaction is required, additional fly ash would be needed.

We suggest constructing the upper 4 to 6 inches of the LVC zone using crushed limestone silty gravel similar to KDOT AB-3-Type material to reduce the above stated swell potential associated with cohesive LVC materials or on-site soils that are allowed to dry excessively. This granular zone would reduce the moisture fluctuations in the bottom portion of the LVC zone and, also provide a more stable working surface during construction following inclement weather

Floor Slab Construction Considerations

We recommend that all HVAC supply/return ducts be above floor level as air-flow and heat transfer through these ducts can cause substantial post-construction drying and shrinkage of clay subgrade and result in severe floor slab/interior wall distress.

The use of a vapor retarder should be considered beneath concrete slabs on grade covered with wood, tile, carpet, or other moisture sensitive or impervious coverings, or when the slab will support equipment sensitive to moisture. When conditions warrant the use of a vapor retarder, the slab designer should refer to ACI 302 and/or ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder.

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Where floor slabs are tied to perimeter walls or turn-down slabs to meet structural or other construction objectives, our experience indicates differential movement between the walls and slabs will likely be observed in adjacent slab expansion joints or floor slab cracks beyond the length of the structural dowels. The Structural Engineer should account for potential differential.

PAVEMENTS

Pavement Subgrade Preparation

We recommend pavement areas be prepared as described previously under Site Preparation in the Earthwork section of this report. We also recommend removing any existing fill from within and at least 2 feet beyond the pavement areas proposed for construction. However, if the Owner is willing to accept the risks associated with constructing pavements on existing fill (possible reduced performance or premature pavement failure), consideration could be given to leaving the existing fill in place unless failures are identified during proofrolling as described previously in the Site Preparation of the Earthwork section of this report. The upper 9 inches of resulting exposed subgrade prior to fill placement should be compacted to at least 95% of its maximum dry density by ASTM D-698.

Any additional fill should be approved material free of organic matter and debris that is placed in lifts not to exceed 9 inches in loose thickness and compacted to at least 95% of its maximum dry density at moisture contents above optimum moisture content where clay soils are encountered.

We also recommend the final 18 inches of subgrade beneath pavements and exterior slabs meet the minimum moisture recommendations stated for additional fill in Compaction Requirements of the Earthwork section of this report. This may require subgrade removal, moisture manipulation, and recompaction.

We recommend modifying the final 8 inches of subgrade in all areas to be paved or removing and replacing the upper 8 inches of subgrade soils with suitable granular material. This would improve subgrade support, reduce swell potential, and reduce the tendency for rutting in untreated wet cohesive subgrades by the paving spreader and loaded dump trucks during the paving operation.

The final subgrade should be constructed of one of the following:

■ Modified subgrade by blending Class C fly ash, hydrated lime, cement/cement slurry, or possibly CKD with on-site clay soil

■ Granular subbase of silty gravel meeting KDOT requirements for AB-3 base

■ Crushed concrete or limestone subbase over a geo-grid or engineering fabric

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If used, we recommend applying the modifying agent at an application rate sufficient to achieve a minimum laboratory CBR value of 25. This can typically be obtained with Class C fly ash contents of about 14% to 16% or lime contents of about 4% to 6%, based on the dry weight of the soil, although this may result in objectionable dusting problems. A more precise application rate should be developed based on additional laboratory testing. A lime slurry application (or the use of granular materials) may reduce the dusting problems.

It has been our experience that some CKD products have excessively high sulfate contents that would react adversely when mixed with soils, causing undesirable swell and heave. When CKD is considered, we recommend that a recent chemical laboratory analysis is submitted to us for review prior to approval of the CKD product.

Because of the potentially deleterious heave that could result if hydrated lime is used to modify shale or soil that contains sulfates, such as gypsum zones or seams, we recommend that shale or overlying soil above the shale not be modified with hydrated lime unless extensive additional laboratory and field testing is performed to determine if excessive sulfates are present and if they would react adversely with the hydrated lime.

The lime-, cement-, or fly ash-modified subgrade or silty gravel (KDOT AB-3) subbase should be compacted to at least 98% of its standard Proctor maximum dry density at a final moisture content within 2 percentage points of its optimum moisture content by ASTM D-698. The modified zone should extend at least 1 foot beyond the edge of the pavement. Soils mixed with Class C fly ash should be compacted within 2 hours following blending operations. Recognized guidelines, such as those specified by the KDOT should be followed in the mixing and blending of lime or fly ash-modified material.

Cohesive pavement subgrades, including fly ash-modified materials, can lose strength if subjected to prolonged wetting/drying and/or freeze/thaw conditions or they can become swell susceptible if allowed to dry excessively before paving operations. Therefore, it is important that the recommended moisture content of cohesive, subgrades in pavement areas be maintained.

As a check, we recommend the moisture content be evaluated about 1 to 2 days before paving operations. If drying or disturbance/loosening of the subgrade materials has occurred at this time, measures should be taken to adjust their moisture content and/or recompact the subgrade soils before paving operations. If the subgrade was previously modified with fly ash and recompaction is required, additional fly ash would be needed.

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Pavement Section Thicknesses

Specific information on the type and volume of traffic anticipated at this site was not provided.

We anticipate that traffic on most of the pavements will consist of personal vehicles (cars and pickups). More repetitions of traffic are anticipated in drive lanes. The following table presents typical minimum thicknesses of pavements constructed on subgrades modified with fly ash or lime for similar projects. The thickness recommendations for parking areas are based on car traffic only. As part of the layout design of the facility, we recommend the designer use signs and preventive structures to restrict truck traffic from entering these areas. In addition, during construction we recommend preventing any contractor traffic on areas of stabilized subgrade or partial thickness pavement. Heavy loaded vehicles operating on these surfaces will cause significant damage resulting in deterioration and reduction in pavement life.

For areas subject to concentrated and repetitive loading conditions, such as dumpster pads, truck delivery docks, and ingress/egress aprons, we recommend using at least 7 inches of reinforced Portland cement concrete pavement, underlain by at least 4 inches of crushed stone. Prior to placement of the crushed stone the areas should be thoroughly proofrolled. For dumpster pads, the concrete pavement area should be large enough to support the container and tipping axle of the refuse truck.

Minimizing subgrade saturation is an important factor in maintaining subgrade strength. Water allowed to pond on or adjacent to the pavement could saturate the pavement and cause premature pavement deterioration. We recommend sloping all pavement surfaces to provide rapid surface drainage. Typically, 2% slopes are used to facilitate rapid surface drainage.

Positive surface drainage beyond the edge of the paved areas should be maintained. Design measures that could reduce the risk of subgrade saturation and improve long-term pavement performance would include crowning the pavement subgrade to drain toward the edges of the pavement area, rather than to the center, and installing surface drains next to any area where surface water can pond.

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TYPICAL MINIMUM PAVEMENT SECTIONS (INCHES) 7

COMPONENT

CAR PARKING & DRIVE

AREAS, LIGHT DUTY1

TRUCK DRIVE AREAS

MEDIUM DUTY2

PORTLAND CEMENT CONCRETE OR

ROLLER COMPACTED CONCRETE:

Air Entrained 4,000 Psi Compressive 580 Psi Flexural

5.0 6.0

ASPHALTIC CONCRETE:

Surface Course 3 and Base Course 4

2.0

3.5

2.0 5.0

MODIFIED SUBGRADE:

■ Class C Fly Ash (about 14% to 16%) or

■ Hydrated Lime (about 4% to 6%) or

■ Crushed Aggregate Base5 or

■ Crushed Aggregate6 on Tensar BX-Type 1 Geogrid or Mirafi HP-370 or equivalent.

5-inch thickness beneath parking areas 7-inch thickness beneath drives

8.0 8.0 8.0 8.0

1. Based on automobile traffic only. Heavier traffic loads (such as wandering heavy trucks) would require greater pavement thickness (a minimum of 6 inches).

2. Based on 15,000 moderate to heavy buses/trucks during the life of the pavement in drive areas. Higher traffic loads would require greater pavement thickness.

3. Surface course material should conform to one of the following specifications:

■ City of Wichita Specifications for Type SC-1 Asphalt

■ 1990 KDOT Specifications for Type BM-2 Asphalt with a minimum stability value of 1800 pounds

■ 2007 KDOT Specifications for Class A Commercial Grade Asphalt Type SM-9.5A or SM-12.5A We recommend the surface course asphalt not contain recycled asphalt product (RAP). The mix design should utilize the appropriate Performance Graded (PG) asphalt cement for the project location and traffic. The approved mix design should have an air void content of 3% to 5% at the optimum asphalt cement content.

4. Base course material should conform to one of the following specifications:

■ City of Wichita Specifications for Type BC-1 Asphalt

■ 1990 KDOT Specifications for Type BM-4 Asphalt with a minimum stability value of 1500 pounds

■ 2007 KDOT Specifications for Class A Commercial Grade Asphalt SR-12.5A or Type SR-19A The maximum allowable recycled asphalt material in the base course mixes should be limited to 35%. The mix design should utilize the appropriate Performance Graded (PG) asphalt cement for the project location and traffic. The approved mix design should have an air void content between 2% and 5% at the optimum asphalt cement content.

5. Crushed Aggregate should consist of crushed stone, crushed gravel, or crushed recycled concrete. Virgin crushed aggregate should conform to the quality requirements of 1990 KDOT Specification Section 1105 or 2007 KDOT Specification 1104. The gradation of the material should be similar to KDOT materials AB-1 or AB- 3, with a maximum of 15% material passing the #200 sieve.

6. Recycled crushed concrete should have a maximum particle size of 2.5 inches and have a gradation similar to the City of Wichita specification Section 404 for Geogrid Reinforced Aggregate Base. Aggregate materials conforming to other aggregate base course specifications may be considered on a project basis.

7. The recommended pavement thicknesses presented in this table could be reduced if the pavements are supported on cement-modified subgrade. Recommendations for cement stabilization could be provided upon your request.

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Pavement design methods are intended to provide structural sections with adequate thickness over a particular subgrade such that wheel loads are reduced to a level the subgrade can support.

The support characteristics of the subgrade for pavement design do not account for shrink/swell movements of an expansive clay subgrade such as the soils encountered on this project. Thus, the pavement may be adequate from a structural standpoint, yet still experience cracking and deformation due to shrink/swell related movement of the subgrade. It is, therefore, important to minimize moisture changes in the subgrade to reduce shrink

Openings in pavements, such as foliage areas installed to comply with landscape code requirements, are sources for water to collect and migrate beneath pavements, and thereby degrade the subgrade support. This is especially applicable for islands with raised concrete curbs, irrigated foliage, and near-surface site soils of impervious clay. The civil design for the pavements with these conditions should include features to restrict, or to collect and discharge excess water from the islands. This could include installing an impervious membrane liner beneath the entire island, or as a minimum, installing trenched lean concrete or rolled sheeting (around the perimeter of the island) that seals against the concrete curb of the island and extends from the ground surface to a depth of at least 3 feet. Alternately, trench drains could be installed around the perimeter of the islands at depths of at least 3 feet, backfilled with free-draining granular material, and connected to sumps with pumps or to collector drain lines that flow to storm sewers or positive outfalls.

The typical pavement thicknesses presented in our table assume periodic maintenance will be performed throughout the life of the pavement. Preventive maintenance should be planned and provided for through an on-going pavement management program. Preventive maintenance activities are intended to slow the rate of pavement deterioration, and to preserve the pavement investment. Preventive maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g. surface sealing and scheduled overlays).

Preventive maintenance is usually the first priority when implementing a planned pavement maintenance program and provides the highest return on investment for…