OWRNC Phase 3 - Geotechnical Report.pdf

OREPORT COVER PAGE

Geotechnical Engineering Report

Ohio Western Reserve National Cemetery Improvements Rittman, Wayne Co., Ohio

February 20, 2019 Terracon Project No. N6185159

Prepared for:

Anderson Engineering of Minnesota, LLC

Plymouth, Minnesota

Prepared by:

Terracon Consultants, Inc.

Parma, Ohio

Terracon Consul tants, Inc. 12460 Plaza Dr ive Parma, Ohio P (216) 459-8378 F (216) 459-8954 terracon.com

REPORT COVER LETTER TO SIGN

February 20, 2019

Anderson Engineering of Minnesota, LLC 13605 1st Avenue North, Suite 100 Plymouth, Minnesota 55441

Attn: Mr. Eric Sautbine, P.E. – Project Manager P: (763) 412-4000 E: esautbine@ae-mn.com

Re: Geotechnical Engineering Report Ohio Western Reserve National Cemetery Improvements 10175 Rawiga Road Rittman, Wayne Co., Ohio Terracon Project No. N6185159

Dear Mr. Sautbine:

We have completed the Geotechnical Engineering services for the above referenced project. This study was performed in general accordance with Terracon Proposal No. PN6185159 dated September 7, 2018. This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork, the design and construction of foundations and floor slabs for the proposed structures, pavement design and construction, and stabilization of the stream bank and adjacent hillside along Tommy Run.

We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report or if we may be of further service, please contact us.

Sincerely, Terracon Consultants, Inc.

Eric A. Angyal, P.E. Thomas F. McDonnell, P.E.

Senior Engineer Principal

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REPORT TOPICS

INTRODUCTION

SITE CONDITIONS

PROJECT DESCRIPTION

GEOTECHNICAL CHARACTERIZATION

GEOTECHNICAL OVERVIEW

EARTHWORK

SHALLOW FOUNDATIONS

FLOOR SLABS

SEISMIC CONSIDERATIONS

PAVEMENTS

FROST CONSIDERATIONS

SEPTIC SYSTEM

SLOPE STABILITY

GENERAL COMMENTS

FIGURES

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 Ohio Western Reserve National Cemetery Improvements

10175 Rawiga Road Rittman, Wayne Co., Ohio Terracon Project No. N6185159

February 20, 2019

INTRODUCTION

This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed Ohio Western Reserve National Cemetery Improvements to be located at 10175 Rawiga Road in Rittman, Wayne Co., Ohio. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

■ Subsurface soil and rock conditions ■ Foundation design and construction

■ Groundwater conditions ■ Floor slab design and construction

■ Site preparation and earthwork ■ Seismic site classification per IBC

■ Dewatering considerations ■ Streambank and slope stabilization

■ Excavation considerations ■ Pavement design and construction

■ Frost considerations

The geotechnical engineering Scope of Services for this project included the advancement of 12 test borings to nominal depths ranging from approximately 10 to 50 feet below existing site grades and one Wildcat Dynamic Cone Penetrometer Test (WCDPT) to a depth of about 6.5 feet.

Maps showing the site and test 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 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.

Ohio Western Reserve National Cemetery Improvements ■ Rittman, Wayne Co., Ohio February 20, 2019 ■ Terracon Project No. N6185159

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Item Description

Parcel Information

The project site is located at 10175 Rawiga Road in Rittman, Wayne Co., Ohio. The entire 273-acre cemetery has a footprint of approximately 2,700 feet (east-west) by 3,300 feet (north-south) and is located about 1,900 feet south of Seville Road. Latitude: 41.0001° N, Longitude: 81.8119° W (approximate). See Site Location

Existing Improvements

The site includes existing paved roadways, two Committal Shelters, an Administration Building, an Honor Guard Building, a Welcome Center, asphalt paths, gravel drives, a Wash Bay building, etc.

Current Ground Cover

Portions of the site include interments with landscape areas. The eastern portion of the site is wooded and includes Tommy Run, a creek at the base of an approximately 35-foot high slope. The northeast portion of the site includes grass lawn areas as well as woods and areas with tall weeds, vegetation, stockpiled soil, and construction debris. An existing gravel drive to the north of burial Sections 9 through 12.

Existing Topography

Much of the site is relatively flat and portions are gently sloped. Existing site grade is about Elevation 1170 feet MSL near the northwest corner of the site and the grades generally fall to the south and east. Grades are near Elevation 1078 feet MSL along Tommy Run at the toe of the slope in the southeast portion of the site and near Elevation 1112 feet MSL at the top of the slope.

Geology

Available geologic references suggest the site subsurface conditions will consist of ground moraine silty clay glacial till of Late Wisconsinan Age overlying Cuyahoga Formation shale and sandstone bedrock of Mississippian Age. Bedrock topography maps and ODNR water well logs suggest shale bedrock may be present about 45 to 80 feet below existing site grades. We understand that some portions of the site have been previously filled to achieve the existing site grades.

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:

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Item Description

Information Provided

Project information was provided in emails from Anderson Engineering between August 31 and February 19, 2019, as well as from various project documents included with, or accessed via links in those emails.

The following information was provided to Terracon:

1) A project plan set dated 1/29/2016

2) PSI geotechnical report dated April 3, 2015

3) A conceptual cross-section for stabilization of Tommy Run prepared by others

4) A 17-page undated Statement of Work Document

5) A 4-page Statement of Work Clarification and Fee Preparation document dated 8/29/2018

6) Drawing L-101 titled “Soil Boring Locations” received via email on

November 26, 2018

7) Meetings with Anderson on September 8, 2018, and January 10,

8) An email dated January 14, 2019, that included a link to an undated and untitled Tommy Run area topographic drawing, a partial project plan set dated December 7, 2018, an undated project narrative document, project Earth Moving specifications dated January 29, 2016, and a drawing titled “Earthwork Cut & Fill Map” dated May 25, 2015

9) Drawing C-501 dated December 7, 2018, titled “Expansion Area Overall Grading Plan” received via email on February 11, 2019

Project Description

The proposed project will include the following:

1) Stabilization of approximately 150 linear feet of the bank of Tommy Run that is being destabilized by erosion;

2) A new maintenance drive in the footprint of the existing gravel drive located north of Sections 9 through 12;

3) Construction of a new Columbaria, Honor Guard Building, and Committal Shelter with associated drives, parking areas, and sidewalks in the northeastern portion of the site, including a new Cortage Lane;

4) Construction of a septic system near the Committal Shelter; and,

5) Regrading of the site required to achieve site grades in the proposed construction areas.

Proposed Structures

A new Honor Guard Building, Columbaria, and Committal Shelter will be constructed in the northeast portion of the site.

The new Committal Shelter will have overall plan dimensions of about 32 feet by 32 feet. The Honor Guard Building will have a footprint of 35 feet by 30 feet. The new Columbaria will consist of 32 individual structures with lengths ranging from about 34 to 56 feet in a rectangular footprint.

Building Construction It is anticipated that the Honor Guard Building will have load bearing stud walls. The Committal Shelter will have stone clad CMU bearing walls and columns. Both of these structures will have wood roof trusses. The Columbaria will have cast-in-place concrete walls.

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Item Description

Finished Floor Elevation The finished floor of the Honor Guard Building will be constructed at Elevation 1150 feet MSL. The finished floor of the Committal Shelter will be constructed at Elevation 1146.3 feet MSL. The finished grades in the area of the new Columbaria will range from about 1139 to 1143 feet MSL.

Maximum Loads

Structural loads were unavailable at the time of this submittal. Given the relatively small sizes of the structures and our understanding of the proposed construction, loads have been assumed to be no greater than:

■ Columns: 50 kips

■ Walls: 2 kips per linear foot (klf)

■ Slabs: 150 pounds per square foot (psf)

Grading/Slopes

As much as 4 to 7 feet of new fill may be required in the areas of the Columbaria and the Committal Shelter. About 1 to 2 feet of new fill will be required for the new Honor Guard Building. Proposed grading in the areas of the proposed septic system is unavailable. Minimal regrading is planned for the new Maintenance drive north of Sections 9 through 12.

About 1 foot of cut to 5 feet of fill is planned for the new parking lot adjacent to the new Honor Guard Building. The new Cortage Lane, to the south of the new Committal Shelter, will require about 5 to 7 feet of new fill.

The failing slope adjacent to Tommy Run, which is approximately 35 feet high, may require extensive regrading, drainage improvements, and reestablished vegetation for surface erosion protection. In addition, the toe of the slope along the Tommy Run stream bank will likely require erosion protection to help with the long-term stabilization of the slope.

Below-Grade and Retaining Structures

Although no retaining structures are planned, erosion protection may be constructed below grade near the toe of the slope along Tommy Run to assist with preventing future erosion of the toe. A septic system may be located to the north or to the east of the new Committal Shelter.

Pavements

A new Maintenance Drive is anticipated to the north of Sections 9 through 12 and will consist of regular duty pavement. A new Cortage Lane, drives, and parking lots are proposed adjacent to the new Honor Guard Building, new Committal Shelter, and new Columbaria. It is anticipated that these will consist of light duty pavement. Anticipated traffic loading for the new Maintenance Drive was provided to Terracon by Anderson via email on February 19, 2019.

Estimated Start of Construction 2020

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

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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 Lean Clay Soft to Very Stiff Brown and Gray Lean Clay 2 Fill Brown Lean Clay

3 Silt Medium Dense to Dense Brown or Gray Sandy Silty or Silty Clayey Sand

4 Gravel Medium Dense Gray Well Graded Gravel 5 Bedrock Highly Weathered Gray Shale or Hard Gray Sandy Silty Clay

Borings SB-1 and SB-2 encountered 12 inches of gravel at the existing ground surface and Borings SB-3 through SB-12 encountered 2 to 8 inches of topsoil.

Borings SB-4, SB-5, and SB-6 encountered soils identified as fill beginning beneath the topsoil and extending to depths ranging from about 3 to 12 feet below the existing ground surface. The fill was composed of sandy lean clay or sandy silty clay with trace amounts of gravel.

The existing fill soils and upper-level natural soils encountered at many of the boring locations to depths ranging from about 1.5 to 3 feet below the existing ground surface appear to have moisture contents in excess of the soil’s optimum moisture content. As such, these soils may require moisture conditioning or chemical stabilization if they are present at proposed subgrade elevations and/or if they are to be reused as engineered fill.

In Boring SB-3, highly to completely weathered, very weak to extremely weak shale bedrock was encountered from a depth of about 37 feet to the 50-foot boring termination depth. The weathered shale was similar to hard clay.

Wildcat Dynamic Cone Penetrometer Test (WDCPT) WC-1, not included in the GeoModel, encountered very loose/soft soils to a depth of about 2 feet below the ground surface followed by medium dense to dense/very stiff to hard soils to the cone penetration termination depth of 6.5 feet.

Groundwater was encountered at a depth of about 1.5 feet in Boring SB-11 and at one foot in WDCPT WC-1. Groundwater was not observed at the other boring locations for the short durations the bore holes could remain open. However, this does not necessarily mean the borings terminated above groundwater, or the water levels summarized at the other locations above are stable groundwater levels. Due to the relatively low permeability of some of the soils encountered in the borings, a relatively long period may be necessary for a groundwater level to develop and

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The groundwater levels in Borings SB-3 and SB-4 should be expected to be near Elevation 1080 feet MSL as they are located near WDCPT WC-1 and Tommy Run.

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 levels during construction or at other times in the life of the structure may be higher or lower than the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project.

GEOTECHNICAL OVERVIEW

The existing fill soils in the area of the new Columbaria are undocumented and these soils should be undercut, moisture conditioned, and properly recompacted. If left in place, total settlements in excess of those that would generally be considered tolerable for the structure(s) may occur.

Due to the elevated moisture contents of the near surface, natural, soft to stiff silty clay and lean clay site soils, these soils could become unstable with typical earthwork and construction traffic, especially after precipitation events. The effective drainage should be completed early in the construction sequence and maintained after construction to avoid potential issues. If possible, the grading should be performed during the warmer and drier time of the year. If grading is performed during the winter months, an increased risk for possible undercutting and replacement of unstable subgrade will persist. Additional site preparation recommendations including subgrade improvement and fill placement are provided in the Earthwork section.

Based upon the relatively light loading anticipated for the new Honor Guard Building, Columbaria, and Committal Shelter, these structures can be supported on conventional spread footing foundations. The foundations should bear in the natural, stiff or better silty clay and lean clay site soils or properly compacted structural fill.

A flexible pavement system is recommended for this site. The Pavements section addresses the design of pavement systems.

The slope stability issues observed along Tommy Run do not appear to be deep-seated failures.

They appear to be the result of over-steepening of the slope due to erosion at the toe of the slope from the creek. The portion of the failing slope along Tommy Run evaluated for this exploration should be regraded to a shallower slope angle, water runoff should be directed away from the slope, and the toe of the slope should be protected with either gabion baskets or be armored with rip-rap stone. Vegetation should also be established on the hillside to help further prevent erosion.

The General Comments section provides an understanding of the report limitations.

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EARTHWORK

Earthwork is anticipated to include clearing and grubbing, excavations, site grading, 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, floor slabs, and pavements.

Site Preparation

Prior to placing and compacting engineered fill, all standing water, existing trees, vegetation, root mat, stockpiled soil, and construction debris should be removed. Complete stripping of the topsoil should be performed in the proposed building, parking/driveway areas, and slope regrading areas.

The existing, undocumented fill soils encountered to a depth of approximately 3 feet in Borings SB-5 and SB-6, in the area of the proposed Columbaria, should be removed, moisture conditioned, and recompacted as further discussed in this report.

After stripping and cutting the site to grade, the resulting subgrade in proposed building and parking/drive areas should be proofrolled using multiple passes from a loaded (minimum weight 20 tons) tandem axle dump truck. The proofrolling should be performed under the direction of the Geotechnical Engineer. Areas excessively deflecting under the proofroll should be delineated and subsequently addressed by the Geotechnical Engineer. Such areas should be stabilized by one of more of the following methods:

1) Undercut to underlying stable soils and replaced with material at an appropriate moisture content, or moisture conditioned (dried) and recompacted to a stable condition in accordance with the earthwork recommendations contained within this report.

2) Partially undercut and replaced with a system of construction grade geogrid and an appropriate layer thickness of stone. The stone type and gradation should be in accordance with the geogrid manufacturer’s specifications. As a general guide, undercut depths and associated stone layer thicknesses may range from about 12 to 24 inches, depending upon the severity of the instability.

3) Chemically stabilized with cement or lime. The chemical type and layer thickness should be selected by a contractor specializing in chemical stabilization of soils. As a general guide, chemical stabilization depths typically range between 12 and 18 inches.

The natural, soft to stiff lean clay and silty clay soils encountered to depths ranging from about

1.5 to 3 feet below the existing ground surface at several of the boring locations are likely wet of their optimum moisture content and may become unstable during earthwork operations. The

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Excessively wet or dry material should either be removed from the project area or moisture conditioned and recompacted.

Fill Material Types

Fill required to achieve design grade should be classified as structural fill and general fill.

Structural fill is material used below, or within 10 feet of structures, pavements or constructed slopes. General fill is material used to achieve grade outside of these areas. Earthen materials used for structural and general fill should meet the following material property requirements:

Soil Type 1, 2 USCS Classification Acceptable Parameters (for Structural Fill)

Low Plasticity Cohesive CL, CL-ML Liquid Limit less than 50 Plasticity index less than 20

Granular GW, GP, GM, GC, SW, SP, SM, SC Less than 10% Passing No. 200 sieve

On-Site Soils CL, CL-ML, GW-GM, SC-SM, ML

Same as Low Plasticity Cohesive and Granular Fill Soils. Boulders and cobbles will need to be removed from fill prior to placement and compaction.

1. Structural and general fill should consist of approved materials 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 prior to use on this site.

2. Imported fill and on-site soils identified as silt (ML) should not be used within 3 feet of finished grade in parking lot, drive, sidewalk, and unheated building areas unless they are cement stabilized to a depth of 16 inches as these soils are highly frost susceptible.

Fill Compaction Requirements

Structural and general fill should meet the following compaction requirements.

Item Structural Fill General Fill

Maximum Lift Thickness

8 inches or less in loose thickness when heavy, self-propelled compaction equipment is used 6 inches in loose thickness when hand-guided equipment (i.e. jumping jack or plate compactor) is used

Same as Structural fill

Minimum Compaction Requirements 1, 2

100% of max. 98% of max.

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Item Structural Fill General Fill

Water Content

Range 1, 3

Low plasticity cohesive: -2% to +2% of optimum High plasticity cohesive: 0 to +4% of optimum Granular: -3% to +3% of optimum

As required to achieve min.

compaction requirements

1. Maximum density and optimum water content as determined by the standard Proctor test (ASTM D 698).

2. If the granular material is a coarse sand or gravel, or of a uniform size, or has a low fines content, compaction comparison to relative density may be more appropriate. In this case, granular materials should be compacted to at least 75% relative density (ASTM D 4253 and D 4254).

3. The on-site lean clay (CL), sandy lean clay (CL), silty clay (CL-ML), silty clayey sand with gravel (SC-SM), and silt (ML) soils will likely require moisture conditioning (drying) to achieve required compaction and a subgrade that is suitably stable.

Grading and Drainage

All grades must provide effective drainage away from the buildings during and after construction and should be maintained throughout the life of the structures. Water retained next to the buildings 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 to storm sewers or onto splash blocks at a distance of at least 10 feet from the buildings.

Exposed ground should be sloped and maintained at a minimum 5% away from the buildings for at least 10 feet beyond the perimeter of the building. Locally, flatter grades may be necessary to transition ADA access requirements for flatwork. After building 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

Shallow excavations for the proposed buildings are anticipated to be accomplished with conventional construction equipment. Upon completion of filling and grading, care should be taken to maintain the subgrade water content prior to construction of floor slabs. Construction traffic over the completed subgrades should be avoided. The site should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. Water collecting over or adjacent to construction areas should be removed. If the subgrade freezes, desiccates, saturates, or is disturbed, the affected material should be removed, or the materials should be scarified, moisture conditioned, and recompacted prior to floor slab construction.

The groundwater table could affect overexcavation efforts in some areas, especially for over-excavation and replacement of lower strength soils. A temporary dewatering system consisting of sumps with pumps could be necessary to achieve the recommended depth of over-excavation.

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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, and/or state regulations. 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.

Construction Observation and Testing

The earthwork efforts should be monitored under the direction of the Geotechnical Engineer.

Monitoring should include documentation of adequate removal of vegetation and topsoil, proofrolling, and mitigation of areas delineated by the proofroll to require mitigation.

Each lift of compacted fill should be tested, evaluated, and reworked, as necessary, until approved by the Geotechnical Engineer prior to placement of additional lifts. Each lift of fill should be tested for density and water content at a frequency of at least one test for every 2,500 square feet of compacted fill in the building areas and 5,000 square feet in pavement areas. One density and water content test should be performed for every 50 linear feet of compacted utility trench backfill.

In areas of foundation excavations, the bearing subgrade should be evaluated under the direction of the Geotechnical Engineer. If unanticipated conditions are encountered, the Geotechnical Engineer should prescribe mitigation options.

In addition to the documentation of the essential parameters necessary for construction, the continuation of the Geotechnical Engineer into the construction phase of the project provides the continuity to maintain the Geotechnical Engineer’s evaluation of subsurface conditions, including assessing variations and associated design changes.

SHALLOW FOUNDATIONS

If the site has been prepared in accordance with the requirements noted in Earthwork, the following design parameters are applicable for shallow foundations.

Design Parameters – Compressive Loads

Item Description Maximum Net Allowable Bearing pressure 1, 2 3,000 psf

Required Bearing Stratum Native stiff or better consistency lean clay, sandy lean clay, or silty clay, or properly compacted structural fill

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Item Description

Minimum Foundation Dimensions Columns: 30 inches Continuous: 18 inches

Ultimate Passive Resistance 3

(equivalent fluid pressures) 288 pcf (Native Stiff Clay or Silty Clay)

Ultimate Coefficient of Sliding Friction 4 0.35 (Native clay or structural fill)

Minimum Embedment below

Finished Grade 5 Exterior footings in unheated areas: 42 inches Interior footings in heated areas: 24 inches

Estimated Total Settlement from Structural Loads 2 Less than about 1 inch

1. The maximum net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation. An appropriate factor of safety has been applied. Values assume that exterior grades are no steeper than 20% within 10 feet of structure.

2. Values provided are for maximum loads noted in Project Description.

3. Use of passive earth pressures require the sides of the excavation for the spread footing foundation to be nearly vertical and the concrete placed neat against these vertical faces or that the footing forms be removed and compacted structural fill be placed against the vertical footing face.

4. Can be used to compute sliding resistance where foundations are placed on suitable soil/materials. Should be neglected for foundations subject to net uplift conditions.

5. Embedment necessary to minimize the effects of frost and/or seasonal water content variations. For sloping ground, maintain depth below the lowest adjacent exterior grade within 5 horizontal feet of the structure.

Foundation Construction Considerations

As noted in Earthwork, the footing excavations should be evaluated under the direction of the 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. Excessively wet or dry material or any loose/disturbed material in the bottom of the footing excavations should be removed/reconditioned before foundation concrete is placed.

If unsuitable bearing soils such as medium stiff or softer silty clay or lean clay are encountered at the base of the planned footing excavation, the excavation 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. This is illustrated on the sketch below.

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Over-excavation for structural fill placement below footings should be conducted as shown below.

The over-excavation should be backfilled up to the footing base elevation, with properly compacted structural fill placed, as recommended in the Earthwork section.

FLOOR SLABS

Based upon our understanding of the existing and proposed site grading in the areas of the new Honor Guard Building, Columbaria, and Committal Shelter, the floor slab subgrades will likely consist of new, structural fill after undercutting, subgrade preparation, and earthwork are complete. Design parameters for floor slabs assume the requirements for Earthwork have been followed. Specific attention should be given to positive drainage away from the structures and positive drainage of the aggregate base beneath the floor slabs.

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Floor Slab Design Parameters

Item Description

Floor Slab Support 1 Minimum 6 inches of free-draining (less than 6% passing the U.S. No. 200 sieve) crushed aggregate compacted to at least 98% of ASTM D 698 3

Estimated Modulus of Subgrade Reaction 2 145 pounds per square inch per inch (psi/in) for point loads

1. Floor slabs should be structurally independent of building footings or walls to reduce the possibility of floor slab cracking caused by differential movements between the slab and foundation.

2. Modulus of subgrade reaction is an estimated value based upon our experience with the subgrade condition, the requirements noted in Earthwork, and the floor slab support as noted in this table. It is provided for point loads. For large area loads the modulus of subgrade reaction would be lower.

3. Free-draining granular material should have less than 6% fines (material passing the #200 sieve). Other design considerations such as cold temperatures and condensation development could warrant more extensive design provisions.

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.

Saw-cut control joints should be placed in the slab to help control the location and extent of cracking. For additional recommendations refer to the ACI Design Manual. Joints or cracks should be sealed with a water-proof, non-extruding compressible compound specifically recommended for heavy duty concrete pavement and wet environments.

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 settlement through use of sufficient control joints, appropriate reinforcing or other means.

Floor Slab Construction Considerations

Finished subgrade, within and for at least 10 feet beyond the floor slab, should be protected from traffic, rutting, or other disturbance and maintained in a relatively moist condition until floor slabs are constructed. If the subgrade should become damaged or desiccated prior to construction of floor slabs, the affected material should be removed and structural fill should be added to replace the resulting excavation. Final conditioning of the finished subgrade should be performed immediately prior to placement of the floor slab support course.

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The Geotechnical Engineer should evaluate the condition of the floor slab subgrades immediately prior to placement of the floor slab support course, reinforcing steel, and concrete. Attention should be paid to high traffic areas that were rutted and disturbed earlier, and to areas where backfilled trenches are located.

SEISMIC CONSIDERATIONS

The seismic design requirements for buildings and other structures are based on Seismic Design Category. Site Classification is required to determine the Seismic Design Category for a structure.

The seismic design requirements for buildings and other structures are based on Seismic Design Category. Site Classification is required to determine the Seismic Design Category for a structure.

The Site Classification is based on the upper 100 feet of the site profile defined by a weighted average value of either shear wave velocity, standard penetration resistance, or undrained shear strength in accordance with Section 20.4 of ASCE 7 and the International Building Code (IBC).

Based on the soil/bedrock properties encountered at the site and as described on the exploration logs and results, it is our professional opinion that the Seismic Site Classification is D.

Subsurface explorations at this site were extended to a maximum depth of 50 feet. The site properties below the boring depth to 100 feet were estimated based on our experience and knowledge of geologic conditions of the general area. Additional deeper borings or geophysical testing may be performed to confirm the conditions below the current boring depth.

PAVEMENTS

General Pavement Comments

Pavement designs are provided for the traffic conditions and pavement life conditions as noted in Project Description and in the following sections of this report. A critical aspect of pavement performance is site preparation. Pavement designs noted in this section must be applied to the site which has been prepared as recommended in the Earthwork section.

It has been assumed that only Asphalt Concrete (AC) pavement design sections are being considered for the proposed project. The anticipated traffic loading for the new Maintenance Drive was provided to Terracon by Anderson via email on February 19, 2019. Traffic loading for the other pavements has not been made available to Terracon at the time of submittal of this report.

Pavement Design Parameters

If the natural soils are stable and consist of lean clay and silty clay encountered in the borings (or stable, properly compacted structural fill consisting of these on-site soils), a subgrade California

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Bearing Ratio (CBR) of 5 and an associated Resilient Modulus (Mr) of 6,000 psi are recommended for AC pavement designs.

These values were empirically derived based upon our experience with the encountered subgrade soils and our understanding of the quality of the subgrade as prescribed by the Site Preparation conditions as outlined in Earthwork.

Pavement Section Thicknesses

Pavement thickness design is dependent upon:

n Anticipated traffic conditions, n Subgrade and paving material characteristics, and n Climate conditions.

In developing our recommendations, we have assumed that traffic loading for the new light duty pavements will consist primarily of automobile traffic with occasional delivery and refuse trucks.

The regular duty will include the same traffic as the light duty pavement along with occasional, light construction equipment including skid steers, back hoes, small, loaded dump trucks with trailers, off-road dumpers, and approximately one semi-truck per week. If heavier vehicle types or higher traffic volumes are expected, Terracon should review and revise these recommendations as necessary.

Based on the design criteria noted above and our experience with similar projects and soil conditions, the asphalt concrete (AC) pavement sections listed on the following table are recommended minimum thicknesses. It has been assumed that the Maintenance Drive north of Sections 9 through 12 will consist of regular duty pavement and the new Cortage Lane and drives and parking lots adjacent to the new Honor Guard Building, new Committal Shelter, and new Columbaria will consist of light duty pavement.

Asphaltic Concrete Design

Layer Thickness (inches)

Light Duty 1 Regular Duty 1

AC 2 4 5

Aggregate Base 6 3 12 4

1. See Project Description for more specifics regarding Light Duty and Regular Duty traffic.

2. A minimum 1.5-inch surface course should be used on AC pavements.

3. New aggregate base should meet ODOT Item 304 Aggregate Base gradation requirements.

4. The existing, 12-inch thick granular base layer, where present, may remain in place, if found to be stable during proof-rolling.

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Terracon understands that the owner desires to reuse the existing 12-inch thick granular base layer encountered in Borings SB-1 and SB-2 as part of the new Maintenance Drive pavement system. Prior to paving, we recommend that the existing granular base layer be proof-rolled in accordance with the Earthwork section of this report to detect unstable areas. If unstable areas are detected, the base material should be removed and stockpiled and the underlying unstable soils should be stabilized. The base could then be replaced and recompacted to the densities specified under Earthwork. If the proof roll indicates the existing granular base is stable during proof rolling, the stone should be moisture conditioned and compacted to the densities specified under Earthwork.

Pavement Drainage

Pavements should be sloped to provide rapid drainage of surface water. Water allowed to pond on or adjacent to the pavements could saturate the subgrade and contribute to premature pavement deterioration. In addition, the pavement subgrade should be graded to provide positive drainage within the granular base section. Appropriate sub-drainage or connection to a suitable daylight outlet should be provided to remove water from the granular subbase.

Subdrainage should be a primary consideration in the proposed pavement areas to prevent water from accumulating within the aggregate base course and causing softening of the subgrade, shrink/swell volume change, or frost heave. To this end, we recommend the installation of pipe underdrains (finger drains) radiating from all catch basins within the pavement. Where surrounded by pavement, the finger drains should be installed on all four sides of the catch basins. At catch basins located along the edge of the pavement, the finger drains should be installed on the sides that abut pavement. Subgrade surfaces should be fine-graded so that water seepage under the pavements will flow to the underdrains or to other suitable drainage outlets. Establishing subgrade slopes during site grading to promote rapid surface and base course drainage will extend its useful life.

We recommend at least 6 inches of free-draining granular material should be placed beneath the new pavements. The use of a free draining granular base will also reduce the potential for frost action. We recommend pavement subgrades be crowned at least 2 percent, to promote the flow of water towards the subdrains, and to reduce the potential for ponding of water on the subgrade.

The subdrains should be hydraulically connected to the free-draining granular base layer.

Subdrains should be sloped to provide positive gravity drainage to reliable discharge points such as the storm water detention basin. Periodic maintenance of subdrains is required for long-term proper performance. Utility lines and the subdrains should be installed as soon after site grading is complete and as far in advance of paving operations as feasible in an attempt to remove perched/surface water and to assist with creating a stable subgrade suitable for paving operations to proceed.

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The pavement surfaces and adjacent sidewalks should be sloped to provide rapid drainage of surface water. Water should not be allowed to pond on or adjacent to these grade-supported slabs, since this could saturate the subgrade and contribute to premature pavement or slab deterioration.

Pavement Maintenance

The pavement sections represent minimum recommended thicknesses and, as such, periodic maintenance should be anticipated. Therefore, preventive maintenance should be planned and provided for through an on-going pavement management program. Maintenance activities are intended to slow the rate of pavement deterioration and to preserve the pavement investment.

Maintenance consists of both localized maintenance (e.g., crack and joint sealing and patching) and global maintenance (e.g., surface sealing). Preventive maintenance is usually the priority when implementing a pavement maintenance program. Additional engineering observation is recommended to determine the type and extent of a cost-effective program. Even with periodic maintenance, some movements and related cracking may still occur and repairs may be required.

Pavement performance is affected by its surroundings. In addition to providing preventive maintenance, the civil engineer should consider the following recommendations in the design and layout of pavements:

■ Final grade adjacent to paved areas should slope down from the edges at a minimum 2%.

■ Subgrade and pavement surfaces should have a minimum 2% slope to promote proper surface drainage.

■ Install below pavement drainage systems surrounding areas anticipated for frequent wetting.

■ Install joint sealant and seal cracks immediately.

■ Seal all landscaped areas in or adjacent to pavements to reduce moisture migration to subgrade soils.

■ Place compacted, low permeability backfill against the exterior side of curb and gutter.

FROST CONSIDERATIONS

The soils on this site are frost susceptible, and small amounts of water can affect the performance of the slabs on-grade, sidewalks, and pavements. Exterior slabs should be anticipated to heave during winter months. If frost action needs to be eliminated in critical areas, we recommend the use of non-frost susceptible (NFS) fill or structural slabs (for instance, structural stoops in front of building doors). Placement of NFS material in large areas may not be feasible; however, the following recommendations are provided to help reduce potential frost heave:

■ Provide surface drainage away from the building and slabs, and toward the site storm drainage system.

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■ Install drains around the perimeter of the building, stoops, below exterior slabs and pavements, and connect them to the storm drainage system.

■ Grade clayey subgrades so groundwater potentially perched in overlying more permeable subgrades, such as sand or aggregate base, slope toward a site drainage system.

■ Place NFS fill as backfill beneath slabs and pavements critical to the project.

■ Place a 3 horizontal to 1 vertical (3H:1V) transition zone between NFS fill and other soils.

■ Place NFS materials in critical sidewalk areas.

As an alternative to extending NFS fill to the full frost depth, consideration can be made to chemically stabilizing the upper 16 inches of pavement and slab-on-grade subgrade or placing extruded polystyrene or cellular concrete under a buffer of at least 2 feet of NFS material.

SEPTIC SYSTEM

Information regarding the proposed septic system was unavailable at the time of this submittal.

Boring SB-10 was advanced in the general area of the primary septic location and Boring SB-8 was advanced in the general area of the alternate septic location. Both of these borings encountered layers of sandy silty clay and sandy lean clay to the 15-foot boring termination depths. Permeability tests were not run on the encountered soils from these borings. However, grain-size distribution tests performed on the upper-level silty clay and lean clay site soils from other borings indicate that the soils consist of 70 to 75 percent silt/clay size particles (fines).

SLOPE STABILITY

Mechanics of Stability

Slope stability analyses take into consideration material strength, presence and orientation of weak layers, water (piezometric) pressures, surcharge loads, and the slope geometry.

Mathematical computations are performed using computer-assisted simulations to calculate a Factor of Safety (FS). Minor changes to slope geometry, surface water flow and/or groundwater levels could result in slope instability. Reasonable FS values are dependent upon the confidence in the parameters utilized in the analyses performed, among other factors related to the project itself.

Geometric Analysis Results

Field observations suggest Tommy Run is scouring the toe of approximately 125 linear feet of the hillside along the west bank of the creek and destabilizing (over-steepening) the slope. As the slope becomes over-steepened, additional soils are sloughing from the hillside into the creek and is being washed away. It also appears that surface runoff may be draining onto portions of the slope from above, causing additional erosion of the slope surface.

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Topographic data shown on the partial project plan set dated December 7, 2018, indicates the creek bottom generally ranges from about Elevation 1077 to 1078 feet MSL and the top of the slope is generally near Elevation 1112 feet MSL in the area under investigation. Water in Tommy Run is only about 1 to 2 feet deep in the project area. The existing slope face is generally at a slope angle of 38 degrees (about 1.28 horizontal : 1 vertical) or steeper. The toe of the slope is located at, or immediately adjacent to, the creek bottom along the portion of the slope that is being destabilized. Evidence of deep-seated (rotational or block failure) slope movements was not observed during our site visits.

A representative cross-section (Section A-A shown on the Exploration Plan for this area) of the slope was evaluated using slope geometry from the partial project plan set, soil strength parameters obtained from samples tested from Borings SB-3 and SB-4, information from WDCPT WC-1, and our experience in conjunction with the computer program Slide Version 2018 8.0221.

Unstable Slopes and Follow Up Analyses

The results of our stability analyses suggest the Factor of Safety of the existing slope with respect to global stability is near 1.0. Typically, where pavements are supported at the top of the slope, a Factor of Safety of 1.3 is considered suitable.

The slope was then modeled with the slope regraded at angles of 2:1 (26.5 degrees) and 2.5:1 (21 degrees) to…