36E77618R0062-008.pdf

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44 Wood Avenue, Suite I ● Mansfield, MA 02048 ● 508-623-0101 www.rwgillespie.com

19 September 2014

David C. Webster, AIA, LEED AP

PDT Architects

49 Dartmouth Street

Portland, ME 04101

Webster@pdtarchs.com

Subject: Geotechnical Engineering Services

Proposed AE Research Addition

VA Jamaica Plain Campus

Boston, Massachusetts

RWG&A Project No. 0435-011

Dear Mr. Webster:

R. W. Gillespie & Associates, Inc., (RWG&A) is pleased to present the attached report of

Geotechnical Engineering Services for the proposed AE Research Addition at the VA Jamaica

Plain Campus in Boston, Massachusetts. This work was performed in general accordance with

RWG&A Proposal No. P-8521.GI, Modification No. 1, dated 07 July 2014. The purpose of the services was to obtain information needed for geotechnical engineering evaluations in support of foundation design for the proposed AE Research Addition.

The attached report provides logs of previous subsurface explorations by others and of recent test borings by RWG&A, results of geotechnical engineering evaluations, and design recommendations made for the proposed AE Research Addition located at the north end of the circa 1997 Ambulatory Care Addition. RWG&A understands the proposed AE Research Addition will be three-stories high with a basement.

Subsurface conditions consist of fill over alluvial soils underlain by glaciofluvial soils, overlying glaciolacustrine soils and till, on bedrock. Bedrock is conglomerate locally called Roxbury

Puddingstone. Free water levels in test borings and observation wells occur near the interface between soil and bedrock.

Subsurface conditions are suitable for support the proposed AE Research Addition on rock bearing drilled shafts. Ground floors that will support heavy settlement-sensitive equipment (e.g., the

Magnetic Resonance Imaging (MRI) machine) will need to be structural slabs supported by drilled shafts. Ground floors in other areas may be either slabs-on-grade, built after removal of the existing fill and replacement with compacted granular fill, or structural slabs.

R.W. Gillespie & Associates, Inc. Page -2-

RWG&A appreciates the opportunity to be of service on this project, and has enjoyed working with VA, PDT Architects, and Becker Structural Engineers, Inc. If there are any questions regarding the attached report, or if RWG&A can be of further service, please do not hesitate to contact us.

Sincerely, R. W. GILLESPIE & ASSOCIATES, INC.

Copy: Daniel S. Burne, P.E, Becker Structural Engineers, Inc. — via email

G:\PROJECTS\0400\0435 0435-01 1\Reports20 14-09-19 01 Report 0435-011 .docx

Geotechnical Engineer

1 :md via email

RWG&A Project No. 0435-011 19 September 2014

R. Gillespje & Associates, In

Report of

GEOTECHNICAL ENGINEERING SERVICES

for

PROPOSED AE RESEARCH ADDITION

VA JAMAICA PLAIN CAMPUS

BOSTON, MASSACHUSETTS

Prepared for

PDT ARCHITECTS

PORTLAND, MAINE

Prepared by

R. W. GILLESPIE & ASSOCIATES, INC.

MANSFIELD, MASSACHUSETTS

/1 3(fl NI(EiSO?I ‘.YkE

/ I AV

\Charles R. Nickerson State of Masichusetts License No. 31159 Civil

RWG&A ProjecE No. 0435-011 19 September 2014

R.W. Gillespie & Associates, Inc.

RWG&A Project No. 0435-011 -i- 19 September 2014

TABLE OF CONTENTS

1.0 INTRODUCTION

1.01 Background

1.02 Scope of Services

1.03 Excluded Services

2.0 SUBSURFACE EXPLORATION

2.01 Subsurface Exploration for Research Addition

2.02 Subsurface Exploration for 1997 Addition

3.0 LABORATORY TESTING

4.0 SUBSURFACE CONDITIONS

4.01 Soils

4.02 Bedrock

4.03 Groundwater

5.0 EVALUATION OF GEOTECHNICAL DATA

5.01 Proposed Foundation Loads

5.02 Foundation Considerations

5.03 Construction Considerations

6.0 RECCOMENDATIONS

6.01 Site Preparation

6.02 Foundations

6.03 Ground Floor Slabs

6.04 Foundation Walls and Elevator Pit

6.05 Underground Utilities

6.06 Temporary Excavations

7.0 CLOSURE

TABLES:

Table I. Selected Record Documents for the Ambulatory Care Addition

Table II. Summary of Subsurface Explorations

FIGURES:

Figure 1. Locus Map

Figure 2. Exploration Location Plan

APPENDICES:

Appendix A. Exploration Logs

Appendix B. Groundwater Observation Well Construction Detail

Appendix C. Laboratory Test Results

Appendix D. Subsurface Information for 1997 Addition

RWG& A Project No. 0435-011 Page 1 of 13 19 September 2014

1.0 INTRODUCTION

1.01 Background

The VA Jamaica Plain Campus is located at 150 South Huntington Avenue in the Jamaica Plain neighborhood of Boston, Massachusetts, as illustrated on Figure 1, Locus Map. RWG&A’s understanding of the proposed AE Research Addition (Research Addition) is based on communications with PDT Architects and Becker Structural Engineers, Inc., site visits, and review of the record documents for the Ambulatory Care Addition (1997 Addition) listed in Table I, Selected Record Documents for the Ambulatory Care Addition.

The Research Addition will be located at the north end of the 1997 Addition. Overall dimensions of the Research Addition are about 100 feet east to west by 55 feet north to south. Based on the above information, the 1997 Addition is supported on caissons (a.k.a., drilled shafts) and spread footings bearing on bedrock. It is understood that the basement level ground floors for the 1997 Addition are slab-on-grade construction built after removal of the existing fills down to the naturally deposited soils and replacement with compacted granular fill.

1.02 Scope of Services

RWG&A’s geotechnical engineering services were performed to develop subsurface information, laboratory test data, and to make geotechnical engineering evaluations for the Research Addition.

As performed, RWG&A’s scope of services included the following:

1. Visited the site and observed conditions exposed at ground surface, drill rig access, and reviewed information regarding underground utilities at the Jamaica Plain Campus near the

Research Addition.

2. Reviewed readily available geologic maps, subsurface information prepared by others, and record drawings for the 1997 Addition for use in geotechnical evaluations.

3. Provided geotechnical engineering consultation relative to subsurface conditions described in the record documents, and regarding foundation and ground floor slab type.

4. Prepared a geotechnical subsurface exploration program to obtain site specific soil, bedrock, and groundwater information.

5. Marked and located the test borings in the field by tape survey methods from fixed features shown on the drawings provided. Contacted DigSafe to locate and mark public underground utilities.

6. Arranged for a subcontractor to drill four test borings. RWG&A provided technical monitoring of drilling activities so that depths, locations, and sampling could be modified in response to the subsurface conditions encountered.

7. Installed a groundwater observation well in one of the completed boreholes.

R.W. Gillespie & Associates, Inc. Page 2 of 13

8. Designed and performed a laboratory testing program to aid in estimation of geotechnical engineering properties of bedrock. The laboratory testing consisted of three unconfined compressive strength tests on intact bedrock cores.

9. Evaluated acquired data with respect to the Research Addition including seismic site class, foundation depth, drilled shaft foundations, allowable bearing capacity, lateral load resistance, ground floor slab type, foundation drainage, and anticipated construction dewatering and excavation support requirements.

10. Prepared this report of geotechnical evaluation presenting the findings, conclusions and geotechnical engineering recommendations.

1.03 Excluded Services

RWG&A’s scope of services did not include an environmental site assessment relative to oil and hazardous materials or evidence of a potential release or threat of oil or hazardous materials on, below, or around the site. It is understood that environmental site assessments have been performed by others. RWG&A anticipates that disposal requirements for fill and soil, bedrock, and groundwater from the Research Addition construction will be provided by the VA’s environmental consultant. The scope of services also did not include any service to investigate or detect the presence of mold or other biological contaminants, or any service that was designed or intended to prevent or lower the risk of the occurrence of an infestation of mold or other biological contaminants (MOBC infestation).

2.0 SUBSURFACE EXPLORATION

2.01 Subsurface Exploration for Research Addition

The subsurface exploration program for the Research Addition consisted of four test borings

(designated B-101 through B-104) advanced between about 30 to 48 feet below local ground surface. Figure 2, Exploration Location Plan, shows the approximate locations of the test borings.

The recent explorations were drilled on 22, 23, and 24 July 2014 by Great Works Pump & Test

Boring, Inc., of Rollinsford, New Hampshire, using a track-mounted drill rig.

Standard Penetration Testing (SPT) with split-barrel sampling was performed in general accordance with ASTM D1586, Standard Test Method for Penetration Test and Split-Barrel

Sampling of Soils. SPT tests and samples were taken semi-continuously in the fill materials and at about 5-foot intervals through the naturally deposited soils. The test borings were advanced with

4-inch diameter steel casing using drive and wash drilling methods through fill and soil, and about

11 to 12.5 feet into bedrock using a roller cone drill bit and an NQ (1.874 inch diameter rock core) double tube core barrel.

The exploration activities were coordinated and monitored by RWG&A, who also prepared the test boring logs included as Appendix A. Soil descriptions used on the logs are in general accordance with ASTM D2488, Standard Practice for Description and Identification of Soils (Visual-Manual

Procedure). Stratification lines shown on the logs represent the estimated thickness of fill, the boundaries between the different soil types, and the approximate depth to bedrock; the actual

R.W. Gillespie & Associates, Inc. Page 3 of 13 transitions will be more gradual and vary in elevation over short horizontal distances. Subsurface information should only be considered representative of subsurface conditions encountered within the vertical reach of the test borings, at the locations, and on the date(s) they were drilled.

A groundwater observation well to measure stabilized free water levels was installed in the completed borehole designated B-101. The groundwater well installation detail is presented in

Appendix B, Groundwater Observation Well Construction Detail.

As-drilled locations of the test borings made for the Research Addition were measured in the field by RWG&A using taping and/or pacing survey methods with reference to fixed site features.

Ground surface elevations at the test boring locations were estimated to the closest half-foot by linear interpolation of ground surface contours shown on the Record Drawing revised dated

9/19/03 prepared for the VAMC Boston Ambulatory Care Addition project titled, Proposed

Utility, Grading & Drainage Plan (North), Drawing No. 1-L14, prepared by Payette Associates, Inc. Test boring locations and associated ground surface elevations should be considered accurate only to the degree implied by the methods used to determine them. RWG&A recommends the as-drilled locations and ground surface elevations of the test borings be surveyed by the project surveyor or site/civil engineer. The surveyed test boring locations and elevations will need to be shown on contract drawings.

2.02 Subsurface Exploration for 1997 Addition

The VA provided logs of test borings drilled by Guild Drilling Company, Inc. in 1994 (designated

B-1through B-18) and by Carr-Dee Corporation in 1997(designated B-201 through B-210), for the

1997 Addition. Test borings B-3 and B-7, and B-201 and B-210 were located near the Research

Addition and have been shown, herein, on Figure 2 for reference. The 1994 test borings were advanced with 4-inch diameter steel casing using drive and wash drilling methods with SPT sampling. These borings were advanced into bedrock with a roller cone drill bit; rock cores were obtained in selected test borings drilled in 1994 with an NV-II (1.996 inch diameter rock core) double tube core barrel. A groundwater observation well was installed in the completed borehole

B-3. The 1997 test borings were drilled by hollow-stem auger methods with SPT sampling, and without coring bedrock.

Test boring logs, water level measurements, location plans, and an interpretive summary table are presented for informational purposes in Appendix D, Subsurface Information for 1997 Addition.

RWG&A is unable to ensure the accuracy or completeness of information provided by others, either because doing so is impossible, or because errors and omissions others may have committed when assembling the information. RWG&A does not accept responsibility for use, interpretation, or accuracy of information prepared by others.

3.0 LABORATORY TESTING

Laboratory compressive strength tests were performed on three bedrock samples cut from the cores taken in the Research Addition test borings. The tests were performed in general accordance with ASTM D 7012 Standard Test Methods for Compressive Strength and Elastic Moduli of Intact

Rock Core Specimens under Varying States of Stress and Temperatures, Method C.

R.W. Gillespie & Associates, Inc. Page 4 of 13

The dimensions of the cut samples did not conform to the tolerances of ASTM D 4543 Standard

Practices for Preparing Rock Core as Cylindrical Test Specimens and Verifying Conformance to

Dimensional and Shape Tolerances and were capped to have flat and parallel top and bottom surfaces. The above non-conformances would cause the test results to be lower than, but representative of, the bedrock unconfined compressive strength. The tests were performed at the

RWG&A soil and materials testing laboratory, which is accredited by the American Association of

State Highway and Transportation Officials (AASHTO). Test results are provided in Appendix C.

4.0 SUBSURFACE CONDITIONS

Descriptions of the soil, bedrock, and groundwater conditions encountered in the test borings made for the 1997 Addition and the Research Addition are presented below. Descriptions of subsurface conditions encountered in test borings B-1, B-7, B-201 and B-210 made for the 1997 Addition have been included. An interpretive summary of subsurface conditions is provided in Table II, Summary of Subsurface Explorations.

4.01 Soils

Beneath the surficial asphalt parking areas, Portland cement walkways, and the loamed and grassed landscaped ground surface, the test borings encountered five soil units overlying bedrock.

Individual units were absent in some of the test borings. Proceeding downward from ground surface the soil units, as described on the test boring logs, are as provided below.

Fill: Each boring encountered fill to depths ranging from about 4.5 to 13.5 feet below local ground surface. The fill consisted of silty sand, sand with gravel, and gravelly sand with silt, dark brown.

Brick fragments were encountered in test boring B-103, rock fragments were noted on the log of

B-3, and cobbles were noted on the log of B-7. (Note: It is anticipated that fill observed in the previous test borings located near the Research Addition might have been removed and replaced with compacted granular or other fill materials in connection with the construction of the 1997

Addition. In turn, fill descriptions on the logs of the test borings drilled in 1994 and 1997 might not be representative of current conditions.)

Alluvial: Naturally deposited alluvial soils consisting of fine sand, little to few silt, and few medium sand, light brown, were encountered below the fill. Boulders were note in the alluvial soil on the log of B-3. Based on SPT N-value blow counts the relative density of the alluvial soils ranged from very loose to dense, and averaged about 35 to 65 percent, or medium relative density.

Encountered thicknesses in the vicinity of the Research Addition ranged from 3 to 11.5 feet. The soil unit was not observed in B-104, and not indicated on the logs for test borings B-7, B-201 and

B-210.

Glaciofluvial: Medium to very dense (i.e., relative density about 35 to 85 percent) glaciofluvial soils were encountered below the alluvial soils. The glaciofluvial soils were described as fine to coarse sand, little to trace gravel, and little silt; color varied locally from brown to light brown to gray-brown. Encountered thicknesses ranged from 1.5 to 22 feet. The glaciofluvial soils were over bedrock in test borings B-102 and B-3, and over the refusal surface encountered in B-201.

R.W. Gillespie & Associates, Inc. Page 5 of 13

Glaciolacustrine: Glaciolacustrine soils were encountered below the glaciofluvial soils, and above bedrock in B-101, B-103, B-104, and B-7. SPT blow count N-values indicate the glaciolacustrine soils have medium relative density of about 35 to 65 percent. The glaciofluvial soils were described as fine sand, with little to some silt, brown. Encountered thicknesses ranged from about

3.5 to 20 feet.

Till: Till was apparently encountered in test boring B-210 drilled for the 1997 Addition, and might be present beneath the Research Addition, especially where the bedrock surface locally undulates.

Description of the Till on the test boring log of B-210 was as follows: Dense coarse to fine sand, trace gravel, inorganic silt, cobbles. Encountered thickness of the Till was about 10.2 feet. Based on the SPT N-value blow counts indicate the relative density of the till is dense. Till in the Boston area is typically dense to very dense and contains cobbles and boulders (i.e., boulders are stones greater than 12 inches in size). (Note: A boulder was noted at the top of the Till on the log of test boring B-8, see Appendix D.)

4.02 Bedrock

Depth to bedrock encountered in the test borings located near the research addition ranged from about 17.5 to 35.5 feet below local ground surface when the test borings were made. Bedrock elevation contours are shown on Figure 2. The elevation contours were estimated by linear interpretation based on ground surface elevations and the combined fill and soil thicknesses measured in the test borings. The elevation contours are provided to indicate general trends in the bedrock surface. Local variations and undulation of the bedrock surface elevation should be anticipated.

Recovered bedrock cores taken in the recent test borings were described as fresh to slightly weathered, moderately hard, medium grained to aphanitic, gray conglomerate (ROXBURY

PUDDINGSTONE) with occasional high angle fractures and jointing; highly fractured zones were encountered locally. Rock Quality Designation (RQD) was calculated for the bedrock cores. RQD is a modified core recovery ratio that provides an estimate of the in-place bedrock quality in accordance with the classification system indicated below. RQD is calculated by measuring the sum of core pieces with lengths equal to or longer than 4 inches (i.e., about twice the core diameter). The percentage ratio of the added length of the core pieces divided by the total length of core drilled is the RQD. The RQD ranged from about 0 to 96 percent, and averaged 47 percent.

RQD

(Percent) Bedrock Quality

90 to 100 Excellent

75 to 90 Good

50 to 75 Fair

25 to 50 Poor

0 to 25 Very Poor

Based on the RQD of the Research Addition bedrock cores, the bedrock quality ranges from

Excellent to Very Poor, and on average Poor. Results of the laboratory unconfined compressive

R.W. Gillespie & Associates, Inc. Page 6 of 13 strength tests of the three rock core samples ranged from about 3,580 to 12,980 pounds per square inch, and averaged about 8,330 pounds per square inch.

Where indicated on the logs of the test borings made for the 1997 Addition, the bedrock was described as gray, dark gray or multi-colored conglomerate. Neither the recovery ratio or RQD was not provided on the 1994 or 1997 logs of test borings made for the 1997 Addition; the bedrock was described as “fractured” on the log of test boring B-1.

4.03 Groundwater

Free water levels measured in the test borings made for the Research Addition are indicated on the test boring logs in Appendix A. On 03 September 2014, or about six weeks after the observation well was installed in B-101, free water was measured at a depth of 36.8 feet or about elevation 29.2 feet (about 1.3 feet below the estimated interface between soil and bedrock), see Appendix B. Free water levels in the previous test borings when drilled, and stabilized levels measurements in the monitoring wells, are presented in Appendix D.

In general, free water levels measured in test borings and observation wells located near the Research Addition have ranged from 5.2 feet below to 3.5 feet above the estimated interface between soil and bedrock. Water levels at the site will fluctuate due to season, temperature, rainfall, proximity to underground utilities, and construction activity near the area of the Research Addition. It is understood that foundation drainage was not provided for the 1997 Addition.

5.0 EVALUATION OF GEOTECHNICAL DATA

Soil, bedrock, and groundwater conditions for the previous and recent test borings (note: drilled about 20 years apart) are very similar to one another. Inconsistencies in descriptions can be attributed to differences in classification systems used to describe the fill materials, naturally deposited soils, and bedrock. Geotechnical evaluations made for this report have been based on the following:

Previous test borings drilled for the 1997 Addition.

The record documents listed in Table I

Performance of the 1997 Addition foundation and ground floors.

Recent test borings drilled for the Research Addition and laboratory bedrock test results.

The 30 percent schematic design drawings for the Research Addition.

If additional and/or differing information becomes known prior to or during construction, then the evaluations and recommendations provided in this report will need be reviewed by RWG&A to confirm their continued applicability.

R.W. Gillespie & Associates, Inc. Page 7 of 13

5.01 Proposed Foundation Loads

Becker Structural Engineers, Inc. provided preliminary foundation reactions via email dated 15

August 2014 3:20AM. Foundation reactions range from about 30 kips to 430 kips (Allowable

Stress Design) or from about 40 kips to 540 kips (Load Resistance Factor Design). In accordance with the 2012 International Building Code and the Massachusetts Amendments to the

International Building Code 2009 (Basic/ Commercial) Eighth Edition, the design recommendations provided in this report are intended to be used with Allowable Stress Design load combinations. Proposed site grading, and settlement tolerances determined by PDT

Architects and Becker Structural Engineers were not provided when this report was prepared.

When information becomes available RWG&A should be provided the opportunity to review additional information and verify continued applicability of the recommendations in this report.

5.02 Foundation Considerations

If the Research Addition were to be supported on compacted granular fill and/or the naturally deposited soils, then differential settlements between the 1997 Addition and Research Addition would be expected to be more than an inch, which RWG&A anticipates would not be tolerable.

Based on the above considerations, technically feasible foundation types include micropiles and drilled shafts.

Micropiles are bored, grouted-in-place deep foundation elements that would develop their load-carrying capacity by bond in the underlying bedrock. Drilled shafts were used to support the

1997 Addition and consisted of end-bearing foundation elements, without permanent casings, with the bottom of shafts socketed a minimum of 6 inches into hard bedrock. Based on installation duration and load testing requirements associated with micropiles, and the performance of the

1997 Addition foundation; RWG&A recommends the Research Addition also be supported on drilled shafts.

Ground floors may be either structural slabs supported by drilled shafts, or slabs-on-grade built after removal of the existing fill and replacement with compacted granular fill. A layer of aggregate base fill will be needed to cushion between parts of the foundation supported on drilled shafts (e.g., drilled shaft caps and tie beams) and soil supported slab-on-grade floors, to reduce abrupt differential settlements between bedrock supported foundations and soil supported floors.

5.03 Construction Considerations

Protection of existing buildings and nearby utilities from disturbance during excavation and construction of the Research Addition is a foundation construction issue. Tolerable lateral and vertical movements of the 1997 Addition, underground utilities, and other nearby structures should be determined for construction purposes by the Structural Engineer and Architect during final design of the Research Addition.

Temporary Excavations: Removing soil near the 1997 Addition will change current unbalanced lateral earth pressures acting on foundation walls which might result in lateral movement, settlement, cracking of the walls and ground floors, and movement of underground utilities. The

Contractor’s responsibilities for construction of the Research Addition should include designing

R.W. Gillespie & Associates, Inc. Page 8 of 13 and providing temporary lateral support, bracing, and shoring of the 1997 Addition based on the

Contractor’s planned construction methods and sequencing.

Construction Vibrations: Vibrations from construction activities might have deleterious effects on occupants, vibration sensitive equipment, and the existing structures. If self-propelled vibratory drum rollers are used to compact fill, then they might need to be operated in static mode. If compaction requirements cannot be met with this approach, then light, hand-operated compaction equipment and thinner lifts of backfill might be needed to reduce vibrations to tolerable levels and achieve compaction requirements.

Construction Dewatering: Groundwater levels observed during the explorations were within a few feet of the interface between soil and bedrock. The Contractor should be advised that the on-site fill and naturally deposited soils are sensitive to disturbance when wet. It will be important to pitch temporary construction ground surfaces to divert surface runoff away from excavations, and to remove groundwater infiltration to reduce disturbance of exposed fill and soils. RWG&A anticipates that groundwater control could be accomplished to depths of about 1 foot below free water levels encountered during construction through the use of ditches, sumps, and open pumping methods. The Contractor should identify and provide any applicable permits for the discharge and/or disposal of effluent from the construction dewatering system.

Use of On-site Soils: RWG&A’s scope of services did not include an environmental site assessment and has only considered the use of the on-site fill and naturally deposited soils from a geotechnical perspective. Much of the information provided by the VA listed in Table I consisted of analytical test results for characterization of the fill, soil, and groundwater for oil and/or hazardous materials for the 1997 Addition. It is understood the VA has an environmental consultant for the Jamaica Plain Campus. RWG&A anticipates the VA’s environmental consultant will assess issues related to the impacts of oil and/or hazardous materials on construction of the

Research Addition including earthwork and foundation construction, disposal of excess materials on and/or off site, worker health and safety, and preparation of a release abatement measure plan in accordance with regulatory agency and Massachusetts Contingency Plan requirements.

From a geotechnical perspective, RWG&A anticipates that on-site topsoil will be stripped and either incorporated into landscaped areas or hauled off-site. Topsoil and organic materials are not considered suitable for use as common fill. Materials from foundation and utility excavations are expected to consist of fill, sand, and silty sand, which are not anticipated to be suitable for use as compacted granular fill, but might be suitable for use as common fill in landscaped areas. If on-site fill or naturally deposited soils are proposed for use other than common fill, then the soil should be stockpiled separately and tested to determine if it meets specification requirements for the proposed use.

6.0 RECCOMENDATIONS

Recommendations presented below are provided for use in design and construction of the geotechnical aspects of Research Addition. Foundation and site work construction will be greatly influenced by subsurface conditions at the project site. RWG&A recommends foundation design and construction be in compliance with the requirements of all applicable codes, regulations, and

R.W. Gillespie & Associates, Inc. Page 9 of 13 ordinances. RWG&A understands that, when this report was prepared, VA requires to project design and construction be in compliance with the latest edition of the International Building Code which is the 2012 International Building Code

. The State of Massachusetts adheres to the

Massachusetts Amendments to the International Building Code 2009 (Basic/Commercial) Eighth

Edition.

6.01 Site Preparation

1. Obstructions to drilled shaft construction should be removed from the Research Addition area prior to installation. Due to the previously developed nature of the site, the Contractor should be sensitive to the potential of encountering obstructions such as remnants of previous structures, building foundations, and underground utilities (note: both active and abandoned) during site work activities and drilled shaft installation. Where such items are encountered beneath the Research Addition plan limits they will need to be excavated to their full extent, removed, and replaced with compacted granular fill. It is anticipated that obstruction removal would be accomplished by hydraulic excavators and hydraulic hammers in open excavations and by rock core bits in drilled shafts.

2. Excavations adjacent to the 1997 Addition and utilities to remain should be designed to limit movements to tolerable amounts as determined by the project Architect, Structural and Civil Engineers. The Contractor’s excavation procedures, bracing, shoring and temporary excavation support design, should be submitted for informational purposes, and review and comment by the VA and Research Addition design engineers, prior to construction.

3. Site grading should provide positive drainage away from Research Addition both during and after construction.

4. Backfill should be placed in level, uniform lifts and compacted to at least 95 percent of the maximum dry density as determined by ASTM D1557, Test Method for Laboratory

Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft (2,700 kN-m/m )), (ASTM D1557). In confined areas, backfill should be placed in lifts not exceeding 6 inches in uncompacted thickness (note: maximum particle size 3 inches).

5. Only compacted granular fill may be used to backfill excavations made to remove obstructions, below ground floors, and to backfill drilled shaft caps and tie beams. Gravel borrow (Mass Highway M1.03.0 Type a) for compacted granular fill should be a well-graded sand and gravel mixture meeting the following gradation requirements:

Screen or Sieve Size Percent Passing

6 inches 100

½ inch 50-85

No. 4 40 - 70

No. 50 8-28

No. 200 0-10

Note: Maximum particle size should be limited to 3 inches within 2 feet of caps, tie beams, ground floor slabs and grade beams, and/or if compacted by hand-guided equipment.

R.W. Gillespie & Associates, Inc. Page 10 of 13

6.02 Foundations

6. The Research Addition needs to be designed to withstand lateral, uplift, and overturning forces due to earthquake. The naturally deposited soils encountered in the previous and recent test borings are not considered susceptible to liquefaction. In accordance with the

2012 International Building Code and the Massachusetts Amendments to the

International Building Code 2009 (Basic/Commercial) Eighth Edition, the soil profile at the site is classified as Site Class D.

7. The Research Addition may be supported on drilled shafts socketed a minimum of 6 inches into hard, competent bedrock and that develop load-carrying capacity in bearing.

The shafts should be designed for an allowable bearing pressure of 20 tons (40 kips) per square foot. Drilled shaft design should be consistent with applicable parts of ACI

336.3R-93, Latest Edition, Design and Construction of Drilled Piers.

8. Drilled shafts should have a minimum diameter of 2 feet. Based on the foundations reactions provided and recommended allowable bearing pressure, anticipated drilled shaft diameters would range from about 2 to 4 feet.

9. Bottoms of drilled shaft caps, foundation walls, and tie beams, in unheated locations should be a minimum of 4 feet below the lowest adjacent exterior ground surface for frost protection.

10. Lateral loads from wind and earthquake may be resisted by earth pressure against sides of drilled shafts, foundation walls and tie beams and by friction between the bottoms of drilled shafts and bedrock subgrades. An earth pressure equivalent fluid unit weight of

125 pounds per cubic foot per foot below finished grade may be used for lateral resistance.

Batter drilled shafts are not recommended.

11. Drilled shafts should be spaced a minimum of two diameters from center-to-center.

Installed drilled shafts should not vary from design locations more than 1/24 th of the drilled shaft diameter or 3 inches, whichever is less. Drilled shafts should not be out of plumb more than 1 inch in 10 feet for the installed depth. As-built cross sections and diameters of should not be less than design dimensions for their respective installed depth.

12. Drilled shaft lengths are anticipated to range from about 20 to 40 feet below current, local ground surface elevation. Drilled shafts need to be socketed a minimum of 6 inches into hard, competent bedrock over their entire bottom and perimeter. It should be anticipated that individual drilled shaft subgrades might occur on sloping bedrock surfaces, and sockets might extend several feet into bedrock. The bearing surface should be cleaned of soft, loose, and disturbed bedrock fragments. Drilled shaft bearing subgrades be documented by remote video photography methods.

13. Project design and specifications should require temporary casings. The temporary casing will need to be steel and sufficiently strong to resist collapse and sufficiently water tight to exclude any foreign materials during placing of concrete.

R.W. Gillespie & Associates, Inc. Page 11 of 13

14. Concrete should not be placed until the rock conditions have been verified, and cleaning of the drilled shaft bottom has been adequately performed. If water is present in drilled shaft excavation and cannot be removed, then concrete should be placed using a tremie or pumped concrete methods.

15. The drilled shaft Contractor should submit prepare a site specific plan that identifies type, capacity, layout and work space of the drilling equipment, material safety data sheets for any proposed drilling fluids used in the work, qualifications of the Contractor and driller(s), and protocols for spill and clean-up/disposal of excavated materials.

16. Project specifications should require materials testing and inspection during in accordance with VA specifications Section 31 63 26 Drilled Caissons, latest edition. Special inspection of the drilled shafts should also be in accordance with 2012 International

Building Code

, Section 1705.8 Cast-in-place deep foundations, Table 1705.8 Required

Verification and Inspection of Cast-In-Place Deep Foundations.

6.03 Ground Floor Slabs

17. Ground floors that will support heavy settlement-sensitive equipment (e.g., the Magnetic

Resonance Imaging (MRI) machine) will need to be structural slabs supported by drilled shafts. Ground floors in other areas may be either slabs-on-grade, built after removal of the existing fill and replacement with compacted granular fill, or structural slabs.

Slab-on-grade ground floors may be based on a subgrade modulus of 150 pounds per cubic inch.

18. The tops of drilled shaft caps, foundation walls, and tie beams should be placed a minimum of 12 inches below the bottom of ground floor slabs. A 12-inch thick layer of aggregate base fill will be needed beneath slab-on-grade floors to reduce abrupt differential settlements between the bedrock supported foundation and slab-on-grade ground floors.

19. It is understood that foundation drainage was not provided for the 1997 Addition. At the minimum, the foundation walls and floor slabs should be damp proofed to minimize moisture infiltration. It is anticipated design and construction details of floor slabs, including concrete thickness, reinforcing, control joint depth and spacing, and the vapor retarder type and thickness, will be provided by the project Structural Engineer and Architect based on slab used and floor finishes.

20. Granular fill beneath slab-on-grade floors will need to be compacted to at least 95 percent of the maximum dry density as determined by ASTM D1557. Beneath structural floor slabs, granular fill will need to be compacted to at least 92 percent of the maximum dry density as determined by ASTM D1557.

6.04 Foundation Walls and Elevator Pit

21. Foundation walls with unbalanced earth pressures acting upon them should be designed to withstand an at-rest equivalent fluid unit weight of 65 lbs. per cu. ft. (Ko = 0.5). Any foundation walls that cannot be allowed to move or are otherwise restrained, such as ones

R.W. Gillespie & Associates, Inc. Page 12 of 13 attached to building foundations, should be designed for at-rest conditions as well. Lateral load from motor vehicle surcharge can be accounted for by applying a uniform vertical pressure equal to 250 lbs. per sq. ft. multiplied by the at-rest earth pressure coefficient.

22. Typical of elevator pit design and construction, it is anticipated the proposed elevator pit in the Research Addition would be fully waterproofed with a pumped internal sump. The walls and bottom of the elevator pit should be designed to resist hydrostatic uplift pressures with free water level no lower than the exterior finished grade or ground floor finished elevation, whichever is higher. An equivalent fluid unit weight (i.e., combined earth and water unit weight) of 90 pounds per cubic foot is recommended for design of elevator pit and foundation walls below free water level; above free water level an equivalent fluid unit weight of 65 pounds per cubic foot is recommended.

6.05 Underground Utilities

23. Underground utilities may either be earth supported below ground floors or be attached to the Research Addition foundation supported by drilled shafts. In either case, earth-supported utilities will need to pass through over-sized sleeves and/or have flexible connections where they connect to or penetrate the foundation. It is recommended that sleeves and flexible connections allow for 2 inches, minimum, of abrupt differential movement where utilities are affixed to or pass thru drilled shaft caps, foundation walls, tie beams, and other parts of the foundation supported on drilled shafts.

24. Bedding and cover placed below and over earth-supported utilities should be in compliance with the utility and manufacturer requirements for the type of conduit or pipe being installed.

25. Trench backfill below slab-on-grade ground floors, sidewalks and pavements should be systematically compacted in lifts to at least 95 percent of the maximum dry density as determined by ASTM D1557, Test Method for Laboratory Compaction Characteristics of

Soil Using Modified Effort (56,000 ft-lbf/ft (2,700 kN-m/m

)) to reduce post-construction differential settlements.

6.06 Temporary Excavations

Contractors should make themselves aware of, and become familiar with, applicable local, state, and federal safety regulations, including the current OSHA Excavation and Trench Safety

Standards. Construction site safety is considered the sole responsibility of the Contractor, who shall also be solely responsible for the means, methods, and sequencing of construction operations.

RWG&A has not evaluated the earthwork and foundation construction from a site safety perspective. Under no circumstance should the Contractor assume or interpreted this report to mean that VA and/or RWG&A, PDT Architects, and Becker Structural Engineers, Inc. are assuming responsibility for construction site safety or the Contractor’s activities; such responsibility is not being implied and should not be inferred.

R.W. Gillespie & Associates, Inc. Page 13 of 13

26. As a precautionary measure, it is recommended all vehicles and spoil piles be kept a minimum lateral distance from the top of excavations equal to no less than 100 percent of the excavation height.

27. Subsurface soils at this site encountered within the anticipated depths of excavations consist of fill and naturally deposited sand with silt, silty sand, and sand with gravel. The naturally deposited soils are sensitive to disturbance when wet. To reduce disturbance of exposed subgrade soils, it will be important to divert runoff and provide positive grading to shed seepage and runoff. Exposed soils should be compacted to reduce rutting, ponding, and surface water infiltration.

28. The integrity of natural soils and fill must be maintained during cold weather conditions.

Slab subgrades should not be allowed to freeze. The naturally deposited soils are considered to be frost-susceptible. Freezing of subgrade soils beneath floor slabs may result in frost heaving and post-construction settlement and cracking. Every effort should be made to prevent freezing of subgrade soils. In the event that frost penetration occurs, fill or naturally deposited soils should be removed and replaced to the depth of the frozen soils with compacted granular fill. At no time should frozen material be placed as fill.

After floor slabs are built, they should be protected from freezing temperatures by insulation or other suitable methods.

7.0 CLOSURE

This report has been prepared for specific application to the proposed Research Addition to the VA

Jamaica Plain Campus in Boston, Massachusetts and for the exclusive use of PDT Architects and the project design team. These services have been completed in accordance with generally accepted soil and foundation engineering practices. No other warranty, expressed or implied, is made. RWG&A will need to perform a general review of the final design and specifications in order to complete the scope of services on this project. The final design review is intended to determine that earthwork and foundation recommendations have been interpreted in the manner in which they were intended.

In the event any changes are made in the nature, design, or location of the proposed construction, the conclusions and recommendations of this report should be reviewed by RWG&A and reaffirmed or revised in writing. The recommendations presented above are based on the results of widely spaced explorations. The nature of variations between the explorations may not become evident until construction has begun. If variations are encountered, it will be necessary for

RWG&A to re-evaluate the recommendations presented in this report.

RWG& A Project No. 0435-011 19 September 2014

TABLE I

SELECTED RECORD DOCUMENTS FOR THE

AMBULATORY CARE ADDITION

Drawing Number 15-04-01, Site Topography, Veterans Administration Hospital Boston, Mass., dated 15 December 1949, prepared by Coolidge Shepley Bulfinch & Abbott and

Chas. T. Main, Inc.

Drawing Number 15-04-02, Core Boring Data, Veterans Administration Hospital Boston, Mass., dated 15 December 1949, prepared by Coolidge Shepley Bulfinch & Abbott and

Chas. T. Main, Inc.

nd

& 3 rd

Floor – Lighting, Building No. 1A, Additions and Alterations for Research, Veterans Administration Boston, Mass., dated 28 April 1969, prepared by Charles A.

Maguire & Associates.

Note to Bidders, Table 1, Figures 1, 2, 4, and 6, Appendix A, and Appendix C from Haley

& Aldrich, Inc. report titled Report on Geotechnical Design Recommendations for

Veteran’s Administration Ambulatory Care Addition and Parking Deck, for Payette

Associated, Inc., dated June 1994.

Report by Haley & Aldrich, Inc., Proposed Ambulatory Care Addition and Parking Deck, Veteran’s Administration Medical Center, Roxbury, Massachusetts, for Payette

Associated, Inc., date 27 July 1994.

Release Abatement Measure Plan, Veteran’s Administration Medical Center, Ambulatory

Care Addition and Parking Facility, Boston, Massachusetts, RTN:3-11323, prepared by

Haley & Aldrich, Inc., dated 13 December 1996.

Report by Haley & Aldrich, Inc., Supplemental Geotechnical and Environmental Data

Report, Proposed Ambulatory Care Addition, Veteran’s Administration Medical Center, for Payette Associated, Inc., dated 13 March 1997. Geotechnical Laboratory Test Results.

Letter from Haley & Aldrich to Payette Associates, Inc. titled Supplemental Geotechnical and Environmental Recommendations for Design and Construction, dated 13 March 1997.

Sheet 1-S26, Typical Details and General Notes, VAMC Boston Ambulatory Care

Addition, dated 5 June 1997, prepared by Payette Associates Architects Planners.

RWG& A Project No. 0435-011 19 September 2014

TABLE II

SUMMARY OF SUBSURFACE EXPLORATIONS

PROPOSED AE REASEARCH ADDITION

VA JAMAICA PLAIN CAMPUS

BOSTON, MASSACHUSETTS

Test Boring

Designation

Date Drilled

Approximate

Ground Surface

Elevation

(Feet - NGVD)

Encountered Thickness of Unit

(Feet)

Drilled into

Bedrock

(Feet)

Observed Free

Water Depth

(Feet) Fill Alluvial Glaciofluvial Glaciolacustrine Till

Combined

Fill and Soil

Thickness

(Feet)

B-101 July 2014 66 9.5 3 11 12 Not Observed 35.5 12.5 36.8 (OW)

B-102 July 2014 67 4.5 11.5 1.5 Not Observed Not Observed 17.5 12.5 21

B-103 July 2014 67 7 4 2.5 20 Not Observed 33.5 12 30

B-104 July 2014 67 10.5 Not Observed 8.5 12 Not Observed 31.0 11 Not Measured

B-3 May 1994 68.5 5.5 5 8.5 Not Indicated Not Indicated 19.0 18.5 24.2 (OW)

B-7 May 1994 67 13.5 Not Indicated 13 5 Not Indicated 31.5 2.0 31

B-201 February 1997 67

6.5 Not Indicated 22 Not Indicated Not Indicated 28.5R Not Drilled Not Encountered

B-210 February 1997 68 10 Not Indicated 5 3.5 10.2 28.7R Not Drilled Not Encountered

Comments:

1. Elevation Datum: Elevations are in feet and referenced to National Geodetic Vertical Datum (NGVD).

2. An asterisk

Ground surface elevations at February 1997 test boring locations were not provided on the test boring logs. RWG&A estimated the elevations for test borings

B-201 and B-210 shown in the above Table. Elevation were estimated to the closest half-foot by linear interpolation of ground surface contours shown on Figure 1, Exploration Location Plan Ambulatory Care Addition, dated March 1997 provided in the Appendix D.

3. Not Observed: Soil unit was not observed in the 2014 test boring made for the Research Addition.

4. Not Indicated: Soil unit was not indicated on the test boring log of the 1994 or 1997 test boring made for the 1997 Addition.

5. R: Test boring stopped at Refusal. Refusal might have occurred on cobble(s), boulder(s), and/or on bedrock. See test boring logs for definition of Refusal.

6. (OW): Free water level measurement taken in a groundwater monitoring well.

7. Not Measured: Indicates free water did not accumulate in B-104 such that a water level could be measure during or after drilling the test boring.

8. Not Encountered: “NO WATER ENCOUNTERED” noted on logs of test borings B-201 and B-210 made for 1997 Addition. These borings were drilled with hollow-team augers, in turn free water might have been encountered but not observed due to drilling method used.

APPENDIX A

EXPLORATION LOGS

RWG&A (2014)

Geotechnical Engineering Services

VA Jamaica Plain Campus

APPENDIX B

GROUNDWATER OBSERVATION WELL CONSTRUCTION DETAIL

APPENDIX C

LABORATORY TEST RESULTS

APPENDIX D

SUBSURFACE INFORMATION FOR 1997 ADDITION

1994 SUBSURFACE INFORMATION

1997 SUBSURFACE INFORMATION