S02 - 824IC3005 - Geotechnical Report - Woodlawn.pdf

REPORT COVER PAGE

Geotechnical Engineering Report

Woodlawn National Cemetery - Facility Renovation, Improvements, and

Repairs

Elmira, Chemung County, New York

October 30, 2019

Terracon Project No. J5195134

Prepared for:

WFS Federal Services

Frederick, MD

Prepared by:

Terracon Consultants-NY, Inc.

Rochester, New York

Terracon Consultants-NY, Inc. 15 Marway Circle Suite 2B Rochester, New York 14624

P (585) 247 3471 terracon.com

REPORT COVER LETTER TO SIGN

WFS Federal Services

7820B Unit 162 Wormans Mill Rd

Frederick, MD 21701

Attn: Mr. Brian Jacobson, RLA – Director of Planning and Design

P: (703) 822-1615

E: bjacobson@wfsfederal.com

Re: Geotechnical Engineering Report

Woodlawn National Cemetery

1825 Davis Street, Elmira

Chemung County, NY

Dear Mr. Jacobson:

We have completed the Geotechnical Engineering services for the above referenced project. This study was performed in general accordance with Terracon Proposal No. PJ5195134 dated July

23, 2019. This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork and the design and construction of foundations, floor slabs and pavements for the proposed project.

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-NY, Inc.

Zeru Kiffle, E.I.T. Michele A. Fiorillo, P.E.

Staff Engineer Geotechnical Department Manager

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REPORT TOPICS

INTRODUCTION

SITE CONDITIONS

PROJECT DESCRIPTION

GEOTECHNICAL CHARACTERIZATION

GEOTECHNICAL OVERVIEW

EARTHWORK

SHALLOW FOUNDATIONS

SEISMIC CONSIDERATIONS

FLOOR SLABS

LATERAL EARTH PRESSURES

PAVEMENTS

FROST CONSIDERATIONS

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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INTRODUCTION

Geotechnical Engineering Report

Woodlawn National Cemetery

1825 Davis Street

Elmira, Chemung County, New York

INTRODUCTION

This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed Woodlawn National Cemetery to be located at 1825 Davis

Street in Elmira, Chemung County, New York. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

■ Subsurface soil conditions ■ Foundation design and construction

■ Groundwater conditions ■ Floor slab design and construction

■ Site preparation and earthwork ■ Seismic site classification per IBC

■ Demolition considerations ■ Lateral earth pressures

■ Excavation considerations ■ Pavement design and construction

■ Dewatering considerations ■ Frost considerations

The geotechnical engineering Scope of Services for this project included the advancement of five test borings to depths ranging from approximately 6 to 15 feet below existing site grades. B-5 was not drilled due to space constraints with the drill rig and the surrounding graves.

Maps showing the site and boring locations are shown in the Site Location and Exploration

Plan sections, respectively. The boring logs are included 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 project is located at 1825 Davis Street in Elmira, Chemung County, New

York. Approximate site coordinate is latitude of (42.1109° N, 76.8269° W).

Current Ground Cover Grass lawn and asphalt paved parking lot

Existing Topography Site is relatively flat and gently sloping up from east to west and elevation

(El.) ranging from El. 883 to 893 feet amsl.

Woodlawn National Cemetery ■ Elmira, Chemung County, New York

October 30, 2019 ■ Terracon Project No. J5195134

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Item Description

Geology

The project is located within the Allegheny Plateau physiographic province in the central portion of Chemung County. The surficial deposits within this province generally consist of outwash sand and gravel and kame deposits (i.e coarse to fine gravel with sand, proglacial fluvial deposition). The Geologic

Map of New York State Geological Survey map the bedrock underlying the overburden soils as sedimentary shale of Upper Devonian age.

1. References: Fisher, D.W., Isachsen, Y.W., and Rickard, L.V., 1970, Geologic Map of New York State, consisting of 5 sheets: Niagara, Finger Lakes, Hudson-Mohawk, Adirondack, and Lower Hudson, New York

State Museum and Science Service, Map and Chart Series No. 15, scale 1: 250,000.

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

The following documents were provided by WFS Federal Services:

■ Project 824IC3005 Woodlawn Statement of Work

■ Woodlawn Cemetery Map

■ Woodlawn Entrance Gate Fence 1941

■ Woodlawn Grave Devel 787-002 1988

■ Woodlawn Lodge 25-20-06 1949

Project Description

The proposed constructions include:

■ Replacement of existing brown storage shed with a new storage building

■ New covered storage structure for storage of small equipment between the administration and maintenance building

■ New asphalt pavement for the entire maintenance yard

■ Extension of the visitor parking at location previously occupied by the brown storage shed

■ Removal and replacement of foundation for the existing Gettysburg tablet stone

Building Construction

■ Wood frame

■ Slab-on-grade

■ Concrete spread foundations

Finished Floor

Elevation

Finished floor elevations for the buildings are expected to be located near existing grades to minimize earthwork cut and fill operations.

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Item Description

Maximum Loads

(assumed)

■ Columns: 20 to 50 kips

■ Continuous Load-Bearing Wall: 4 kips per linear foot (klf)

■ Slab: 100 psf

Pavements

We assume both rigid (concrete) and flexible (asphalt) pavement sections will be constructed at the site. Anticipated traffic is as follows:

■ Autos/light trucks: 1,000 vehicles per day

■ Light delivery and trash collection vehicles: 20 vehicles per week

■ Tractor-trailer trucks: <1 vehicle per week

The pavement design period is 20 years.

1. If the assumed foundation loads or traffic counts are significantly higher than the actual values, please contact our office.

GEOTECHNICAL CHARACTERIZATION

We have developed a general characterization of the subsurface conditions based upon our review of the subsurface exploration, 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 Surficial Topsoil / Asphalt with aggregate base course

2 Fill

Mixtures of silt, sand and gravel; black and brown; trace wood fragments

3 Native Soil Mixtures of silt and sand with gravel (SM, ML, SW and SP);

brown to gray.

1. Fill was encountered in all borings to depths ranging from 2 to 6 feet below existing grades.

Groundwater Conditions

The boreholes were observed while drilling and after completion for the presence and level of groundwater. The water levels observed in the boreholes can be found on the boring logs in

Exploration Results. Groundwater was not observed in any of the borings with in the explored depths; however, trapped or perched water conditions were occasionally observed at permeable/impermeable interface.

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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. Water may also become temporarily perched over low permeability layers. 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

In general, the site is suitable for the proposed construction based upon geotechnical conditions encountered during the exploration program. The proposed buildings may be supported on shallow foundation bearing upon compacted Structural Fill placed upon proof-rolled native soil.

As part of the proposed construction, there is also a need to remove and replace foundation of the existing Gettysburg tablet stone monument. The monument may also be supported on shallow foundation bearing upon compacted Structural Fill paced on proof-rolled native soil.

The key geotechnical consideration impacting the proposed construction is the presence of approximately 2 to 6 feet of uncontrolled fill in all borings performed for this study (B-5 not drilled).

Existing fill is not suitable to support foundations and slabs due to the risk of greater than normal settlements associated with inherent variations in the nature and relative density of the fill and should be replaced with compacted Structural Fill. The Shallow Foundations section addresses design recommendation for new foundations supporting the building. The Floor Slabs section addresses recommendations for support of the slabs-on-grade. The Pavements section addresses recommendations for support of the exterior pavements.

Monitoring of the construction operations discussed herein will be critical in achieving the design subgrade support. We recommend Terracon be retained to evaluate soil bearing subgrades exposed after excavation to confirm they are suitable for footing, or slab support. Subsurface conditions in the explorations have been reviewed and evaluated with respect to the proposed construction plans known to us now.

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

EARTHWORK

Earthwork will include removal of topsoil or asphalt, removal of existing fill, 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.

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Demolition

As part of the construction, we anticipate removal of existing structures (i.e. slabs; foundations;

pavements; sidewalks; underground utilities; etc.) may be required. Removed buried structures should be backfilled with approved imported Structural Fill, which is placed and compacted in accordance with recommendations presented in this report. We also recommend the following:

■ Existing structures and utilities should be removed from beneath proposed foundations and floor slabs.

■ Existing structures should be removed from proposed pavement areas to a minimum depth of 2 feet below of the pavement subgrade. Existing floor slabs (if left at a minimum depth of 2 feet below the bottom of floor slab) should be broken up to promote drainage and minimize the potential for trapped water.

■ Existing underground pipes may remain in-place if the top of the pipe is at least 2 ft below pavement subgrade or floor slab bottom and filled with Flowable Fill with a minimum compressive strength of 500 psi. Existing piping/structures should be disconnected from other existing piping intended to be left in place and functioning, and properly capped prior to placing Flowable Fill.

Site Preparation

Complete stripping of the topsoil should be performed in the proposed buildings and parking/driveway areas. The existing fill should then be removed in its entirety from within and 5 feet beyond the limits of the new buildings. The exposed subgrades should be proof-rolled with a minimum 10-ton (static weight) smooth drum roller compactor. We recommend a minimum of two overlapping passes in one direction, followed by two overlapping passes in a direction perpendicular to the first passes. The intent is to compact areas with relatively loose surficial soil, to re-compact areas loosened by stripping and fill removal operations, as well as to identify unacceptable subgrade areas. As an alternative, proof-rolling can also be performed with an adequately loaded vehicle such as a fully loaded tandem axle dump truck or other heavy, rubber-tired construction equipment weighing at least 20 tons.

Areas which excessively deflect under the proof-roll should be delineated and subsequently addressed by the Geotechnical Engineer. Unstable subgrades, as identified by the Geotechnical

Engineer, should be over-excavated from the building footprint, footing bearing zones, and pavement areas to competent material and replaced with compacted Structural Fill. After the exposed subgrades have been successfully proof-rolled and unstable areas repaired, Structural

Fill could then be placed in a controlled manner as presented below to achieve the proposed design grades.

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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:

Fill Type

USCS

Classification Acceptable Parameters

Structural Fill

GW, GW-GM, SW,

SW-SM, SP, SM,

GP

Liquid Limit less than 40, Plasticity Index less than 20, and less than 25% retained on No. 200 sieve

Aggregate

Base/Subbase Course

GW, GW-GM, SW,

SW-SM, SP, GP

NYSDOT, Subbase Course, Type 2. Less than 10% passing No. 200 sieve.

General Fill

GW, GP, GM,

SW, SP, SM, CL,

ML

General Fill may be used for general site grading;

General Fill should not be used under settlement or frost-sensitive structures. General Fill should have a maximum particle size of 12 inches and no more than

40 percent by weight passing the No. 200 sieve.

Non-Frost Susceptible

(NFS) Fill

GW, GP, SW, SP

NFS Fill should contain less than 5 percent material passing No. 200 sieve size.

Crushed Stone GP

May be used to level subgrades at the bottom of trenches and to facilitate dewatering. Should be uniform ¾-inch angular Crushed Stone wrapped in a geotextile separation fabric (Mirafi 140N, or similar).

Lean Concrete Not applicable

Lean Concrete should be flowable, self-compacting concrete with a compressive strength between 750 and

2,000 psi.

1. 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 prior to use on this site.

Excavated on-site soils are anticipated to consist primarily of sand and silt mixtures. We do not recommend reusing excavated on-site soils as Structural Fill. It is our opinion excavated non-organic soils (clean from roots, oversized particles, and vegetation) may likely be suitable for reuse as General Fill to attain proposed subgrade elevation, provided material larger than 6 inches in diameter is removed, it is free of deleterious materials, and that during construction proper compaction and optimum moisture content can be achieved. If construction is performed during the wet season, it is possible the moisture content of the excavated soils is in excess of the optimum moisture content required to achieve proper compaction, and that proper compaction of the on-site soils may be very difficult to achieve. We anticipate that imported Structural Fill may then be required. Saturated soils which cannot achieve compaction should be removed or used

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Fill Compaction Requirements

Structural and General Fill should meet the following compaction requirements.

Item Structural Fill General Fill

Maximum Lift Thickness

12 inches or less in loose thickness when heavy, self-propelled compaction equipment is used.

6 to 8 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, 3

95% of maximum dry density below foundations and within 1 foot of finished pavement subgrade

90% of max. above foundations, below floor slabs, and more than 1 foot below finished pavement subgrade

90% of max.

Water Content

Range

Workable moisture levels As required to achieve min.

compaction requirements

1. Maximum density and optimum water content as determined by the modified Proctor test (ASTM D 1557).

2. We recommend testing fill for moisture content and compaction 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 this criterion should extend at least 5 feet horizontally beyond the building footprint.

3. For NFS fill material (with less than 5 percent fines), compaction testing is typically not feasible. We recommend that NFS fill be thoroughly tamped in place in horizontal lifts not to exceed 6 inches loose thickness. Compaction should be by uniform passes of compaction equipment in sufficient number, but not less than four passes, such that no further consolidation is evident. The NFS fill should not be dumped into place but should be distributed in horizontal lifts by blading and dozing in such a manner as to ensure proper placement into final position.

Utility Trench Backfill

Trench excavations should be made with sufficient working space to permit construction including backfill placement and compaction. Trenches should be backfilled with material that approximately matches the permeability characteristics of the surrounding soil to reduce the infiltration and preferential conveyance of surface water through the trench backfill. Fill placed as backfill for utilities located below the slab should consist of compacted Structural Fill or suitable bedding material.

Utility trenches are a common source of water infiltration and migration. All utility trenches that penetrate beneath the building should be effectively sealed to restrict water intrusion and flow

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Structural Fill stated previously in this report.

Grading and Drainage

Grades must provide effective drainage away from the building during and after construction and should be maintained throughout the life of the structure. Water retained next to the building 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 discharging 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 percent away from the building 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 buildings construction and landscaping, 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 structure, 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 foundations and 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.

Groundwater was generally not observed in the borings within the exploration depth. 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, it should be anticipated the groundwater table could rise and affect earthwork. If required, the contractor should select a dewatering method to lower groundwater at least 2 feet below the excavation subgrade in order to minimize bearing surface disturbance during construction of footings and utilities. Dewatering, if required, can likely be accomplished using filtered pumps placed in crushed stone. If ¾-inch

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Crushed Stone is used, a geotextile separation fabric (Mirafi 140N, or equivalent) should be placed between the Crushed Stone and on-site soil.

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. The contractor should be aware that slope height, slope inclination, and excavation depth should in no instance exceed OSHA guidelines. OSHA guidelines 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.

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 proof-roll 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 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 of buildings and tablet stone monument.

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Design Parameters – Compressive Loads

Item Description

Maximum Net Allowable Bearing

Pressure 1, 2

2,500 psf

Required Bearing Stratum

Minimum 12 inches compacted Structural Fill placed upon proof-rolled/compacted native soil. The Structural

Fill should extend a minimum lateral distance of 12 inches from the edge of the foundations.

Minimum Foundation Dimensions Columns: 30 inches

Continuous: 18 inches

Ultimate Passive Resistance

(equivalent fluid pressures) 390 pcf (compacted Structural Fill)

Ultimate Coefficient of Sliding Friction

0.50 (Footing on compacted Structural Fill)

Minimum Embedment below

Finished Grade

Exterior footings in unheated areas: 48 inches

Exterior footings in heated areas: 48 inches

Interior footings in heated areas: 18 inches

Estimated Total Settlement from

Structural Loads

Less than about 1 inch

Estimated Differential Settlement 2, 7

About 2/3 of total settlement

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. These bearing pressures can be increased by 1/3 for transient loads unless those loads have been factored to account for transient conditions. 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. Unsuitable or soft soils should be over-excavated and replaced per the recommendations presented in the

Earthwork.

4. 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. The Structural Fill must extend out and up from the base of the foundation at an angle of at least 60 degrees from vertical for the passive case.

5. 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.

6. 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.

7. Differential settlements are as measured over a span of 50 feet.

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Construction Adjacent to Existing Building

Differential settlement between the addition and the existing building is expected to approach the magnitude of the total settlement of the addition. Expansion joints should be provided between the existing building and the proposed addition to accommodate differential movements between the two structures. Underground piping between the two structures should be designed with flexible couplings and utility knockouts in foundation walls should be oversized, so minor deflections in alignment do not result in breakage or distress. Care should be taken during excavation adjacent to existing foundations, to avoid disturbing existing foundation bearing soils.

New footings should bear at or near the bearing elevation of immediately adjacent existing foundations. Depending upon their locations and current loads on the existing footings, footings for the new addition could cause settlement of adjacent walls. To reduce this concern and risk, clear distances at least equal to the new footing widths should be maintained between the addition’s footings and footings supporting the existing building.

The structural capacity of existing foundations should be evaluated by a licensed structural engineer, where increases in loading are planned.

Design Parameters - Uplift Loads

Uplift resistance of spread footings can be developed from the effective weight of the footing and the overlying soils. As illustrated on the subsequent figure, the effective weight of the soil prism defined by diagonal planes extending up from the top of the perimeter of the foundation to the ground surface at an angle, , of 20 degrees from the vertical can be included in uplift resistance.

The maximum allowable uplift capacity should be taken as a sum of the effective weight of soil plus the dead weight of the foundation, divided by an appropriate factor of safety. A maximum total unit weight of 120 pcf should be used for the backfill. This unit weight should be reduced to

60 pcf for portions of the backfill or natural soils below the groundwater elevation.

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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. Any large cobbles and/or boulders encountered beneath the proposed foundations at the bearing grade elevation shall be removed from the bearing surface as necessary to avoid point-bearing, and then backfilled with properly compacted Structural Fill.

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 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 removal of unsuitable soils below footings should be conducted as shown below. The over-excavation should be backfilled up to the footing base elevation, with imported

Structural Fill, as recommended in the Earthwork section.

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 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 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 15 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.

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FLOOR SLABS

Design parameters for floor slabs assume the requirements for Earthwork have been followed.

Specific attention should be given to positive drainage away from the structure and positive drainage of the aggregate base beneath the floor slab.

Floor Slab Design Parameters

Item Description

Floor Slab Support

Minimum 12 inches of Aggregate Base material compacted to at least 95% of

Modified Proctor (ASTM D 1557) placed directly upon proof-rolled subgrade soils (native or Structural Fill).

Estimated Modulus of

Subgrade Reaction

125 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.

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

Responsive ■ Resourceful ■ Reliable 15 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.

The Geotechnical Engineer should approve 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.

LATERAL EARTH PRESSURES

Design Parameters

In the event that there are structures with unbalanced backfill levels on opposite sides (i.e.

retaining walls), they should be designed for earth pressures at least equal to values indicated in the following table. Earth pressures will be influenced by structural design of the walls, conditions of wall restraint, methods of construction and/or compaction and the strength of the materials being restrained. Two wall restraint conditions are shown. Active earth pressure is commonly used for design of free-standing cantilever retaining walls and assumes wall movement. The "at-rest" condition assumes no wall movement and is commonly used for basement walls, loading dock walls, or other walls restrained at the top. The recommended design lateral earth pressures do not include a factor of safety and do not provide for possible hydrostatic pressure on the walls

(unless stated).

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Lateral Earth Pressure Design Parameters

Earth Pressure Condition

Coefficient for

Backfill Type

Surcharge Pressure 3, 4, 5 p1 (psf)

Effective Fluid Pressures (psf) 2, 4, 5

Drained

Active (Ka)

Granular - 0.31 (0.31)S (37)H

At-Rest (Ko)

Granular - 0.47 (0.47)S (56)H

Passive (Kp)

Granular - 3.25 -- (390)H

1. For active earth pressure, wall must rotate about base, with top lateral movements 0.002 H to 0.004 H, where H is wall height. For passive earth pressure, wall must move horizontally to mobilize resistance.

2. Uniform, horizontal backfill, compacted to at least 95 percent of the ASTM D 1557 maximum dry density, rendering a maximum unit weight of 120 pcf and friction angle of 32 degree.

3. Uniform surcharge, where S is surcharge pressure.

4. Loading from heavy compaction equipment is not included. Hand operated equipment should be used within 4 feet of back of wall.

5. No safety factor is included in these values.

Backfill placed against structures should consist of granular soils. For the granular values to be valid, the granular backfill must extend out and up from the base of the wall at an angle of at least

45 and 60 degrees from vertical for the active and passive cases, respectively.

Subsurface Drainage for Below Grade Walls

Perforated rigid plastic drain lines installed behind the base of any retaining / unbalanced walls, and extends below adjacent grades are recommended to prevent hydrostatic loading on the walls.

The invert of a drain line around a below-grade building area or exterior retaining wall should be placed near foundation bearing level. The drain line should be sloped to provide positive gravity drainage to daylight or to a sump pit and pump. The drain line should be surrounded by clean, free-draining granular material such as NYSDOT Item 203.21 Select Structural Fill; however, we recommend less than 5% passing the No. 200 sieve. The Select Structural Fill should be encapsulated in a filter fabric. The granular fill should extend to within 2 feet of final grade, where it should be capped with rigid or flexible pavement or low permeable fill to reduce infiltration of surface water into the drain system.

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As an alternative to Select Structural Fill, a pre-fabricated drainage structure may be used. A pre-fabricated drainage structure is a plastic drainage core or mesh which is covered with filter fabric to prevent soil intrusion and is fastened to the wall prior to placing backfill.

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.

Pavement Design Parameters

Pavement designs were based on AASHTO Guide for Design of Pavement Structures (1993) and our experience with similar projects. The thickness of each course is a function of subgrade strength, traffic, design life, serviceability factors, and frost susceptibility.

A subgrade CBR of 4 was used for the AC pavement designs, and a modulus of subgrade reaction of 100 pci was use for the PCC pavement designs. The values were empirically derived based upon our experience with the on-site soils and our understanding of the quality of the subgrade as prescribed by the Site Preparation conditions as outlined in Earthwork. A modulus of rupture of 600 psi was used for pavement concrete.

Pavement Section Thicknesses

Frost susceptibility is a major factor in the overall pavement section thickness. The total pavement structural sections presented in this report are based also upon the expected depth of freeze, which for the project site is anticipated at 48 inches. Based on local field data and experience, Responsive ■ Resourceful ■ Reliable 18 and provided positive pavement drainage is maintained, we anticipate that the minimum pavement structural sections presented in the following sections are required to minimize pavement heave and keep cracking within tolerable amounts.

As a result of the fine-grained nature of the in-situ soil, we recommend a separation woven geotextile be placed upon all new approved flexible pavement subgrades prior to placing the subbase course materials. A Mirafi HP270 or approved equivalent may be used. The geotextile will mitigate migration of fines into the overlying subbase course material, which may contribute to its degradation and loss of strength.

The following table provides options for Asphaltic Concrete and for Portland Cement Sections:

Asphaltic Concrete Design

Layer Thickness (inches)

Light Duty Heavy Duty

Asphalt Top Course 2 1.5 1.5

Asphalt Binder Course 2 2.5 3.5

Aggregate Base Course 2 12.0 12.0

1. See Project Description for more specifics regarding pavement type.

2. All materials should meet the current NYSDOT Department of Transportation (NYSDOT) Standard

Specifications.

■ Asphalt Top Course – NYSDOT Section 402 for Type 12.5 F2 Top Course HMA, Item No.

402.127202

■ Asphalt Binder Course – NYSDOT Section 402 for Type 19 F9 Binder Course HMA, Item No.

402.197902

■ Aggregate Base Course – NYSDOT Section 304 for Type 2 Subbase Course, Item No. 304.12

Portland Cement Concrete Design

Layer Thickness (inches)

Light Duty

PCC 2 6.0 8.0

Aggregate Base

12.0 12.0

1. See Project Description for more specifics regarding traffic classifications.

2. All materials should meet the current State, County, and City Department of Transportation (NYSDOT)

Standard Specifications for Highway and Bridge Construction.

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Portland Cement Concrete Design

Layer Thickness (inches)

Light Duty

■ Concrete Pavement - NYSDOT Portland Cement Concrete Section 502, with a minimum compressive strength of 4,000 psi at 28 days.

■ Aggregate Base Course – NYSDOT Section 304 for Type 2 Subbase Course, Item No. 304.12

3. In areas of anticipated heavy traffic, fire trucks, delivery trucks, or concentrated loads (e.g. dumpster pads), and areas with repeated turning or maneuvering of heavy vehicles.

The estimated pavement sections provided in this report are minimums for the assumed design criteria, and as such, periodic maintenance should be expected. Areas for parking of heavy vehicles, concentrated turn areas, and start/stop maneuvers could require thicker pavement sections. Edge restraints (i.e. concrete curbs or aggregate shoulders) should be planned along curves and areas of maneuvering vehicles. A maintenance program that includes surface sealing, joint cleaning and sealing, and timely repair of cracks and deteriorated areas will increase the pavement’s service life. As an option, thicker sections could be constructed to decrease future maintenance.

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. Subdrains should be sloped to provide positive gravity drainage to reliable discharge points. Periodic maintenance of subdrains is required for long-term proper performance.

Openings in pavements, such as decorative landscaped areas, are sources for water infiltration into surrounding pavement systems. Water can collect in the islands and migrate into the surrounding subgrade soils thereby degrading support of the pavement. This is especially applicable for islands with raised concrete curbs, irrigated foliage, and low permeability near-surface soils. The civil design for the pavements with these conditions should include features to restrict or to collect and discharge excess water from the islands. Examples of features are edge drains connected to the storm water collection system, longitudinal subdrains, or other suitable outlet and impermeable barriers preventing lateral migration of water such as a cutoff wall installed to a depth below the pavement structure.

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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 be properly sloped to promote proper surface drainage

■ Drainage systems should be installed below pavements where surrounding areas are anticipated to be wet frequently

■ Joint sealant and seal cracks should be installed immediately

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

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.

■ Install drains around the perimeter of the building, stoops, below exterior slabs, 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.

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■ 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 placing extruded polystyrene or cellular concrete under a buffer of at least 2 feet of NFS material.

GENERAL COMMENTS

Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration. Natural variations will occur between exploration point locations or due to the modifying effects of construction or weather.

The nature and extent of such variations may not become evident until during or after construction.

Terracon should be retained as the Geotechnical Engineer, where noted in this report, to provide observation and testing services during pertinent construction phases. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations.

Our Scope of Services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

Our services and any correspondence or collaboration through this system are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third-party beneficiaries intended. Any third-party access to services or correspondence is solely for information purposes to support the services provided by Terracon to our client.

Reliance upon the services and any work product is limited to our client, and is not intended for third parties.