36C24618R0096-009.pdf

GEOTECHNICAL ENGINEERING REPORT

Community Living Center Expansion McGuire VA Medical Center 1201 Broad Rock Boulevard Richmond, Virginia

Schnabel Reference # 15613010 February 19, 2015

February 19, 2015

Mr. Dave Haun, CIPE, LEED AP BD+C Senior Vice President Design-Aire Engineering, Inc.

220 North College Avenue Indianapolis, Indiana 46202-3702

Subject: Project 15613010, Geotechnical Engineering Report, Community Living Center Expansion, McGuire VA Medical Center, 1201 Broad Rock Boulevard, Richmond, Virginia

Dear Mr. Haun:

SCHNABEL ENGINEERING CONSULTANTS, INC. (Schnabel) is pleased to submit our geotechnical engineering report for this project. This document includes tables, figures, and appendices with relevant data collected for this study. This study was performed in accordance with our agreement dated January 20, 2015.

This report presents the results of subsurface exploration, laboratory testing, and geotechnical engineering analysis for the proposed Community Living Center Expansion project.

SCOPE OF SERVICES

Our agreement dated January 20, 2015 defines the scope of services for this project. The scope of services includes the following:

Subsurface exploration including twelve test borings to depths of 20.5 to 30.5 ft Field engineering services, including site reconnaissance, boring layout, private utility screening at the boring locations and logging of the subsurface exploration Laboratory testing of materials encountered in the subsurface exploration including moisture content, gradation analysis and Atterberg Limits Geotechnical engineering analysis and report, including:

o Estimated subsurface conditions and groundwater levels within the area explored based on data collected in the subsurface exploration o Foundation recommendations for spread footings including a net allowable soil bearing pressure, bearing grades, estimated settlements, minimum dimensions and frost depth o Recommended Seismic Site Class in accordance with IBC 2009 for use in foundation design based on an extrapolation of data collected in the subsurface exploration

Design-Aire, Inc.

o Evaluation of the shrink/swell potential of the soils encountered in the exploration.

o Recommendations for floor slab support, including a recommended modulus of subgrade reaction for use in slab design o Earthwork recommendations for construction of load-bearing fill including an assessment of site soils for use as fill, subgrade preparation, and compaction criteria o Comments on construction dewatering considerations o Construction considerations related to the implementation of our recommendations

PROJECT DESCRIPTION

Site Description and Proposed Construction

The project site is located at the southeast end of the existing Hunter Holmes McGuire Veterans Administration (VA) Hospital on Broad Rock Boulevard in Richmond, Virginia. A Site Vicinity Map is included as Figure 1. The site is a level grassy area on the south side of the existing Community Living Center (CLC) wing. The site extends south to the north edge of the asphalt paved parking lot and is bound on the east by a two-story utility building. An asphalt driveway is located on the west side of the site. Other existing features at the site include a small shelter, asphalt paved walkways, and underground utilities. The ground surface varies from about El 90 to the northwest adjacent to the existing CLC wing to about El 86 to the southeast.

The proposed project will include construction of two additions to the existing CLC wing. The project will consist of the West House and East House expansions. Currently, only the East House expansion is proposed for construction. The East House will initially be a one-story addition with future plans to increase it to a three-story building. This addition will match the existing CLC wing in height and the finished first floor elevation will also match at about El 90.2. A new lobby, corridor and service storage area will connect the north ends of the two houses to the existing CLC wing. The lobby and service storage area will have an elevator shaft leading to a break room and service storage at the basement level. The finished basement floor elevation will also match the existing CLC wing basement at about El

66.2. The elevator pit slab will be at about El 61.2.

The proposed grading for the project will require varying amounts of cut and fill. Excavations of about 24 ft will be required to reach the basement level. The building will have a slab on-grade, masonry and steel framing and a brick façade. Foundation loading information indicates that final interior column footings will have a service load of 375 kips and perimeter column footings will have a service load of 175 kips.

Wall footing loads will be around 6 kips per lineal foot.

Schnabel obtained the site and initial project information from the drawing labeled as VAMC Richmond CAD Measurements Rough Dims which we received from John Skinner. We also received additional project development information from the Building Sections plans we received from Huelat Davis Healing Design. Ehlert/Bryan, Inc. provided the structural load information. We also obtained site information through our review of available site aerial photography and through our site visit.

February 19, 2015 Page 2 Schnabel Engineering Consultants, Inc.

Project 15613010 ©2015 All Rights Reserved

SUBSURFACE EXPLORATION AND LABORATORY TESTING PROGRAM

We conducted a subsurface exploration and field testing program to identify the subsurface stratigraphy underlying the site and to evaluate the geotechnical properties of the materials encountered. This program included test borings. Exploration methods used are discussed below. The appendices contain the results of our exploration.

Subsurface Exploration Methods

Test Borings

Schnabel’s subcontractor, Ayers and Ayers, Inc. of Powhatan, Virginia drilled twelve test borings under our observation on February 2 and 3, 2015. The Standard Penetration Test (SPT) was conducted at selected depths in the borings. Appendix A includes specific observations, remarks, and logs for the borings; classification criteria; drilling methods; and sampling protocols. Figure 2 included at the end of this report indicates the approximate test boring locations. We will retain soil samples up to 45 days beyond the issuance of this report, unless you request other disposition.

Soil Laboratory Testing

Our laboratory performed tests on selected samples collected during the subsurface exploration. The testing aided in the classification of materials encountered in the subsurface exploration and provided data for use in the development of recommendations for design of foundations and earthwork. The results of the laboratory tests are included in Appendix B and are summarized for each stratum in the Site Geology and Subsurface Conditions section of this report. Selected test results are also shown on the boring logs in Appendix A.

Index Testing

We performed index testing on samples collected as part of the exploration to provide soil classifications and to provide parameters for use with published correlations with soil properties. Index testing included performing natural moisture content, Atterberg Limits, and gradation tests on several jar samples of soil representing Stratum A.

SITE GEOLOGY AND SUBSURFACE CONDITIONS

Site Geology

We reviewed existing geologic data and information in our files. Based on this review, the geologic stratigraphy consists of upland terrace deposits of Pleistocene geologic age or older. The terrace deposits are alluvial soils that typically consist of a mixture of clay, silt, sand and gravel. These soils typically exhibit moderate to high strength and low to moderate compressibility.

Generalized Subsurface Stratigraphy

We characterized the following generalized subsurface stratigraphy based on the exploration and laboratory test data included in the appendices.

February 19, 2015 Page 3 Schnabel Engineering Consultants, Inc.

Stratum A: Existing Fill

Existing fill was encountered at all the boring locations to depths of about 13 ft to 28 ft with an average depth of about 19 ft. The fill consisted of sandy fat clay, sandy lean clay, clayey sand and silty sand soils.

These fill soils contained miscellaneous items including brick fragments, crushed stone, gravel, asphalt fragments, and root fragments. We believe these fill soils represent fill used to grade the site and backfill the below-grade foundation walls of the existing CLC. Based on correspondence with Mr. John Skinner there is no documentation of the placement and density testing of the existing fill soils. Boring B-01 encountered a layer of soft clay soils from about 18 to 28 ft. Borings B-08, B-11, and B-12 encountered several obstructions within the fill and we observed concrete fragments in the samples.

The existing fill soils were generally of moderate to high plasticity with liquid limits of about 39 to 58, and plasticity indices of 22 to 34. The moisture contents of the existing fill varied from 13.1 to 22.9 percent.

Based on the Standard Penetration Tests performed, this stratum is generally medium stiff to very stiff: N = 6 to 43 blows per foot (bpf) or medium dense to dense: N = 11 to 57 bpf.

Laboratory tests conducted on several samples representing Stratum A indicate these soils exhibit a medium to high potential for moisture-related volume change (shrink/swell behavior).

Stratum B1: Pleistocene Terrace (Fine-Grained)

Below the existing fill soils of Stratum A and inter-layered with the coarse-grained soils of Stratum B2, more than half of the borings encountered a terrace deposit consisting of lean clay (CL) and fat clay (CH) with varying amounts of sand to depths of 20.5 to 30.5 ft. The natural moisture contents measured in two samples were 17.5 and 21.0 percent. Based on the Standard Penetration Tests performed, this stratum is generally very stiff to hard consistency: N = 19 to 60 bpf.

Stratum B2: Pleistocene Terrace (Coarse-Grained)

Below the existing fill soils of Stratum A and interlayered with the fine-grained soils of Stratum B1, more than half of the borings encountered a terrace deposit consisting of fine to coarse clayey sand (SC) with varying amounts of gravel to depths of about 17.5 to 27.5 ft. The natural moisture contents measured were 13.0 to 21.4 percent. Based on the Standard Penetration Tests performed, this stratum is medium dense to dense: N = 11 to 40.

Groundwater

We encountered groundwater in Borings B-05 and B-07 at depths of 23.5 and 4 ft, about EL 64.5 and 84.5, respectively. Groundwater was not encountered in the remaining borings. After drilling, all the borings caved dry at depths of 2 to 18 ft. The test boring logs in Appendix A include groundwater observations obtained during our subsurface exploration. These data include depths to groundwater encountered during drilling, upon drilling completion, and following completion of the borings. We did not obtain long-term water level readings since we backfilled the test borings upon completion for safety.

The shallow groundwater encountered in Boring B-07 is believed to represent perched groundwater within the existing fill of Stratum A. The groundwater levels on the logs indicate our estimate of the hydrostatic water table at the time of our subsurface exploration. The final design should anticipate the

February 19, 2015 Page 4 Schnabel Engineering Consultants, Inc.

fluctuation of the hydrostatic water table depending on variations in precipitation, surface runoff, pumping, evaporation, leaking utilities and similar factors.

Seismic Site Classification

We evaluated the Seismic Site Class and Seismic Site Coefficients for this project according to the International Building Code (IBC) Section 1615 (2009). Our analysis indicates Site Class D for this location. This Site Class was evaluated based on corrected SPT values and shear strength values from pocket penetrometer test results.

GEOTECHNICAL RECOMMENDATIONS

We based our geotechnical engineering analysis on the information developed from our subsurface exploration and soil laboratory testing, along with the project development plans, site plans, and structural loading furnished to our office. The existing fill soils of Stratum A, although generally medium stiff to very stiff or medium dense to dense, contain some isolated soft layers and deleterious material and it is our opinion that the existing fill soils are not suitable for direct support of the proposed CLC building additions.

In addition, due to the variable nature inherent with such existing fill deposits it is possible that areas of unsuitable existing fill soils may be present at depths below the proposed additions in areas where we did not explore. Additionally, documentation of the existing fill placement is not available to consider the existing fills a controlled structural fill.

Based on the existing fill extending to about El 62 to 71, it is our opinion that the existing fill soils of Stratum A are too deep for undercut and replacement to be economical. Therefore, we recommend an intermediate foundation system such as aggregate piers for support of spread footings for Level 1. The basement level at El 66 is generally expected to extend through the existing fill soils of Stratum A and spread footings supported on suitable natural soils of Strata B1/B2 are considered feasible. The existing fill soils of Stratum A and natural soils of Strata B1 and B2 are generally considered suitable for direct support of the floor slabs. Detailed recommendations are provided in the following sections of the report.

Spread Footings on Aggregate Piers

We recommend aggregate piers to support spread footings for Level 1 of the CLC additions. The aggregate pier foundation system is a refinement of the traditional excavation and replacement method of strengthening soils for settlement control and bearing capacity improvement.

There are two common proprietary aggregate pier systems: Geopiers Rammed Aggregate Piers, a patented product of the Geopier Foundation Company, Inc. and Vibro Piers by Hayward Baker. The systems differ in installation methodology, but the end product of both systems is a stiffened pier support element that can be used to support shallow foundations.

Geopier rammed aggregate pier support elements are constructed by drilling a hole to create a cavity, removing a volume of compressible material (e.g. the existing fill on this site), then building a bottom bulb of clean, open-graded stone while vertically pre-stressing and pre-straining soils underlying the bottom bulb. The pier shaft is built on top of the bottom bulb, using well-graded highway base course stone (VDOT No. 21B) placed in thin lifts (12 inches compacted thickness) above groundwater levels. For shaft

February 19, 2015 Page 5 Schnabel Engineering Consultants, Inc.

portions constructed below the groundwater, clean open-graded aggregate (such as VDOT No. 57) is typically used.

Densification of the bottom bulb and of the shaft lifts is accomplished by using the impact ramming action of a modified hydraulic hammer. The tamper consists of a special steel alloy shaft and a beveled tamper head. The beveled tamper head assists in transferring force laterally during impact densification, resulting in pushing of aggregate against the confined walls of the cavity. The nature of the soil is to “push back”, creating significant lateral pressure buildup in the matrix soil resulting in lateral confinement to the pier elements. In addition to increasing shear resistance at the perimeter of the pier element, the increased horizontal stress in the matrix soil improves the matrix soil and makes it stiffer.

Vibro Piers are constructed in a similar fashion as Geopiers with the exception that the compaction of the aggregate is achieved by vibration and ramming action via a specially-designed, high-energy depth vibrator. Horizontal vibrations are created by a motor and eccentric weight located near the tip of the vibrator. Extension tubes are bolted to the vibrator to allow it to be lowered to the necessary treatment depth. Alternatively, if the pre-drilled hole will not stay open, a bottom feed vibrator equipped with a tremie pipe through which the aggregate is fed can be used.

A preliminary bearing analysis of an aggregate pier-supported, spread footing foundation system indicates that footings bearing on 30-inch diameter pier elements can be sized for a maximum allowable composite bearing pressure of approximately 6,000 psf or more. With column loads and wall loads of up to 375 kips and 6 klf respectively, and typical pier lengths of 15 to 20 feet, the estimated total settlement is expected to be less than 1 inch. However, longer pier elements will likely be necessary to penetrate the existing fill at some locations. We recommend the aggregate piers be designed to limit settlement to ½ inch adjacent to the existing CLC wing.

Aggregate piers are typically installed as proprietary systems by licensed foundation installers. The installer and their designer are responsible for design and installation. The designer would design the aggregate piers to support the proposed structure within the structural design tolerances (i.e. settlement potential, sliding resistance, uplift capacity, etc.).

When foundation plans become available, the aggregate pier design/installer can provide a design/construction cost estimate including the estimated time to install the pier elements. This estimate should include the cost to provide a full-scale pier Modulus Load Test to verify design assumptions. The load test provides the stiffness of the pier element and will provide quality control guidelines for the pier installation procedures. The Modulus Load Test will be performed in the general area of the site considered to be representative of the most critical soil condition.

Spread Footings on New Compacted Structural Fill or Suitable Natural Soils

The basement level at El 66 is generally expected to extend through the existing fill soils of Stratum A and spread footings supported on suitable natural soils of Strata B1/B2 are considered feasible. If existing fill soils are encountered at design bearing grades they should be undercut and replaced with new compacted structural fill, crushed stone, controlled low strength material (CLSM), or lean concrete.

Compacted structural fill should meet the requirements outlined in the Site Grading and Earthwork section discussed below in this report. We recommend footings supported on suitable natural soils of Strata

February 19, 2015 Page 6 Schnabel Engineering Consultants, Inc.

B1/B2 be designed for a net allowable soil bearing pressure of 4,000 psf. This bearing pressure provides a factor of safety against general bearing capacity failure of at least 3.0.

The above allowable soil bearing pressure may be increased by 33 percent for wind and seismic loads when used in conjunction with load combinations defined in IBC 2009 Section 1605.3.2, Alternative Basic Load Combinations for use with allowable stress design. This increase is not applicable for other allowable stress load combinations, strength design, or load and resistance factor design.

All footing subgrades should be observed by the Geotechnical Engineer prior to placement of concrete to evaluate if subgrade materials are as anticipated.

Settlements of shallow foundations supported on suitable natural soils and on properly placed compacted structural fill are not expected to exceed about one (1) inch. Differential settlements between similarly loaded footings are not expected to exceed about half this value. Differential settlement between the additions and the existing CLC building of about one half (½) inch should be anticipated.

Column and wall footings should be at least 24 and 16 inches wide, respectively, for shear considerations. Exterior footings should be founded at least 3 ft below final exterior grades for shrink/swell protection. Interior footings may be founded at nominal depths below the floor slabs. New footing grades for those footings adjacent to existing footings should be constructed at the same elevation. Where bearing grades between adjacent footings vary, the slope between the bottom edges of adjacent footings should not be steeper than 45 degrees (1H:1V).

To further limit the potential for damage from moisture-related volume change of foundation soils, site grades should be set to permit positive drainage of surface water away from the building. Roof drainage from the building should be collected and discharged at least 25 ft from the building.

Floor Slabs

The proposed floor slabs should be supported on suitable existing fill soils of Stratum A or compacted structural fill. A modulus of subgrade reaction, k, of 75 pci should be used in the design of floor slabs.

A four-inch crushed stone or washed gravel capillary moisture barrier should underlie floor slabs on grade. Moisture barrier material should consist of VDOT No. 57 crushed stone. The Contractor should compact the stone in place with at least two passes of suitable vibratory compaction equipment.

The Contractor should compact floor slab subgrades to repair any disturbance that may occur due to construction operations before placing capillary moisture barrier materials. Since floors will be slab-on-grade, footing and utility excavations should be backfilled with compacted structural fill as defined in the Site Grading and Earthwork section of this report.

Site Grading and Earthwork

Proposed building and site grades will require placement of up to about 4 ft of compacted structural fill.

Recommendations for compacted fill subgrade preparation fill soil requirements; placement and compaction criteria are presented in subsequent sections.

February 19, 2015 Page 7 Schnabel Engineering Consultants, Inc.

Compacted Fill Subgrades

Subgrades to receive compacted structural fill for building support should be stripped of vegetation, topsoil, and organic matter. Schnabel’s subsurface exploration indicated topsoil to depths of 0.3 to 0.5 ft below the ground surface. However, stripping of sites typically results in some disturbance and contamination of near-surface soils, particularly during periods of wet weather. Therefore, we recommend a topsoil stripping depth of 0.5 ft be considered for the site during the project planning.

Compacted structural fill subgrades should consist of suitable existing fill soils of Stratum A or new compacted structural fill. These soils are expected to be encountered at shallow depths beneath the topsoil and root mat.

The Geotechnical Engineer should evaluate the suitability of the fill subgrades. The stripped subgrades should be proofrolled with a loaded dump truck to evaluate the subgrade suitability for support of the compacted structural fill prior to any undercutting or initiation of fill placement. Areas that exhibit excessive pumping, weaving, or rutting should be scarified, dried and recompacted, or undercut and replaced with compacted structural fill as recommended by the Geotechnical Engineer. Subgrade evaluation techniques complementary to proofrolling could include a combination of probing with a penetrometer, drilling hand augers, or observing test pits.

Subgrades beyond the building limits that exhibit unsuitable movements during proofrolling may be stabilized by using crushed stone and geotextile working platforms. Recommendations for working platforms should be provided by the Geotechnical Engineer.

If stripping and earthwork operations are performed during an extended period of warm, dry weather, the non-organic portions of the undercut materials may be reused as compacted structural fill. The use of these materials as compacted structural fill will depend on the soil moisture content, and the Contractor's ability to limit contamination of these materials with organic matter during stripping and undercutting.

When removal of unsuitable materials is required, the excavation should be performed in a manner to limit disturbance of the underlying suitable material. The excavation should be performed under the observation of the Geotechnical Engineer to evaluate required excavation depths.

Undercut volumes should be evaluated by cross sectioning. Other methods of calculating volumes of undercut, such as counting trucks, are less accurate and generally result in additional expense. If truck counts are used, we recommend the method of payment be in accordance with Section 109 of VDOT Road and Bridge Specifications.

Compacted structural fill subgrades should be kept free of ponded water. If springs or other flowing water is present at the compacted structural fill subgrade level, the Contractor should direct water to discharge beyond the fill limits. Recommendations for discharging springs should be provided by the Geotechnical Engineer.

Compacted structural fill subgrades should be free of snow, ice, and frozen soils. If snow, ice, or frozen soils are present at subgrade levels, these materials should be removed as recommended by the Geotechnical Engineer.

February 19, 2015 Page 8 Schnabel Engineering Consultants, Inc.

Some existing structures present on site will need to be removed before earthwork construction.

Therefore, buried foundations and other associated debris may be encountered during grading activities.

Existing foundations should be completely removed from the proposed building area. Existing utilities and drainage structures within the building area should be removed and replaced with compacted structural fill.

Compacted structural fill subgrades should not be steeper than about 4H:1V. If steeper slopes are present, subgrades should be benched to permit placement of horizontal lifts of fill.

Compacted Fill

Compacted structural fill should consist of non-organic on-site soils. If off-site borrow materials are needed, these soils should classify CL, ML, SC, SM, SP, SW, GC, GM, GP or GW according to ASTM D2487. Fill materials should not contain particles larger than 3 inches.

Compacted structural fill should be placed in maximum eight-inch thick horizontal, loose lifts. Fill should be compacted to at least 95 percent of the maximum dry density per ASTM D698 (Standard Proctor).

Backfill placed in excavations, trenches, and other areas that large compaction equipment cannot access should be placed in maximum six-inch thick lifts. Backfill should meet the material, placement, and compaction requirements outlined above.

Successful re-use of the excavated, on-site soils as compacted structural fill will depend on their natural moisture contents during excavation. Scarifying and drying of these soils should be anticipated to achieve the recommended compaction. Drying of these soils will likely result in some delays, and may not be possible during cooler, wetter weather. We recommend that the earthwork be performed during the warmer, drier times of the year.

Below-Grade Walls

Below-grade building walls will be braced by the structure preventing movement. Braced basement walls should be designed considering equivalent fluid pressure, gef, as shown in Figure 3. Equivalent fluid pressure factors are presented in Table 1 for the respective backfill conditions. Where applicable, the design should consider surcharge loads using a rectangular earth pressure distribution as shown in Figure 3. The surcharge pressure ordinate should be obtained by multiplying the surface surcharge pressure, q, by the factor in Table 1 for the respective backfill condition. Friction and passive earth pressure factors are also presented in Table 1.

Table 1: Recommended Design Parameters for Walls

Wall Type Backfill Materials

Equivalent Fluid Pressure Factor

(gef)

Surcharge Pressure

Factor Friction Factor

Passive Equivalent

Fluid Pressure Factor

(γP) Braced On-site 50 0.4 0.35 360

Braced Free-draining 35 0.3 0.35 360

February 19, 2015 Page 9 Schnabel Engineering Consultants, Inc.

February 19, 2015 Page 10 Schnabel Engineering Consultants, Inc.

Project 15613010 ©2015 All Rights Reserved

The above parameters consider a horizontal ground surface behind the walls and do not consider foundation loads. We should be contacted to provide alternative parameters if sloping ground surface conditions are anticipated and/or adjacent foundations are expected to exert load on existing and/or proposed below-grade walls.

These design parameters do not consider hydrostatic pressure since we recommend subdrainage behind the walls. Basement walls should be backfilled as recommended below. Basement walls should be damp proofed.

Backfill materials for walls designed considering free-draining backfill should consist of non-plastic material classifying SP-SM, SW-SM, SP, SW, GW-GM, GP-GM, GP or GW according to ASTM D2487.

This classification includes open-graded crushed stone such as VDOT No. 78 or No. 57. Free-draining backfill should be placed in the zone extending from the base of the wall upwards at 45 degrees. Backfill materials for walls designed considering on-site materials used for backfill should consist of material classifying SC, SM, SP, SW, GC, GM, GP or GW according to ASTM D2487.

The Contractor should place backfill in maximum 8-inch thick loose lifts, and compact each lift to at least 95 percent of maximum dry density according to ASTM D698 (Standard Proctor), or to at least 70 percent relative density according to ASTM D4253 and D4254. Only light hand-operated equipment should be used to compact backfill against walls. The Structural Engineer of Record should approve the size of the compaction equipment. If backfill consists of open-graded aggregate, the Contractor should place backfill in maximum 12-inch thick lifts, and compact each lift using suitable vibratory equipment.

Earth pressure recommendations provided do not include hydrostatic pressure since subdrainage will be provided behind the basement walls. Subdrainage should consist of perimeter subdrains located on top of the wall footing, next to the wall. Subdrains should consist of four-inch slotted, corrugated polyethylene tubing according to ASTM F405 (perforated Schedule 40 PVC pipe) surrounded by at least six inches of filter drainage material. Subdrains should drain by gravity to an outlet, or to a sump or storm sewer.

Geocomposite drainage panels consisting of Miradrain G100N or equivalent should be installed on all basement walls when on-site soils are used as wall backfill. Drainage panels should be placed along the entire wall face to within 1.5 ft of finished grade. The Contractor should bind the edges of the panels with drainage geotextile to limit the potential for soil intrusion into the drainage system.

Filter material should consist of VDOT No. 57 aggregate. Drainage geotextile should consist of a non-woven geotextile such as Mirafi 140N or equivalent.

CONSTRUCTION CONSIDERATIONS

Removal of Existing Features

The CLC addition site has numerous structures and subsurface utilities. Existing foundations, slabs and utilities should be completely removed from within the footprint of proposed new structures and replaced with new structural fill.

Temporary Construction Slopes

The basement level is expected to require an excavation of up to about 24 ft below existing grades. We expect that temporary slopes will be utilized for construction of the basement level. We recommend temporary excavation slopes of 1H:1V existing fill soils of Stratum A and natural soils of Stratum B1/B2.

The recommended slope angle requires that the groundwater surface elevation be maintained below the bottom of the excavation.

Shored excavations may be required where space does not allow for temporary sloped excavations.

Shored excavations may be used in conjunction with temporary sloping of the upper portion of excavations. Shored excavation systems should be designed by an engineer retained by the contractor.

The contractor should take responsibility for the design and performance of the shored excavation systems and the safety of their employees working around the shored and sloped temporary excavations.

Aggregate Piers

We recommend that we monitor the rammed aggregate pier installer’s operations on a full-time basis as a Quality Assurance service. Our services will supplement the installer’s internal QC program. Together the QA/QC program will monitor drill depths, pier element lengths, average lift thickness, installation procedures, aggregate quality, and densification of lifts. These items will be documented for each pier element installed to provide a complete installation report.

Aggregate used for piers constructed above the water table should be VDOT Type 21B. It should be compacted to a densification and strength that provides resistance to the dynamic penetration test (ASTM STP 399) of a minimum average of 15 blows per 1.75 inch vertical movement. Aggregate below the water table should be open graded crushed stone meeting VDOT No. 57 size or larger.

One modulus load test should be performed at a location chosen by Schnabel Engineering prior to the start of construction of the production piers. This test will be provided to confirm the subgrade modulus value used in design. The load shall be applied by hydraulic jacks to the center of a circular steel plate equal to the diameter of the pier. The plate shall be centered over a singular pier. The procedure should follow ASTM D-1143. For aggregate piers, the maximum load applied during the test should equal 150% of the maximum pier design stress for aggregate piers.

If at any time during the installation of the aggregate piers it is questionable whether the bottom of the auger hole has remained stable, a bottom stabilization verification test may be performed. This test is conducted by placing a reference bar over the hole after the energy source has been turned off. The tamper bar is marked, and the energy is restarted. If the measured vertical movement exceeds 150% of the value achieved for the load tested pier, added energy shall be used to redensify the bulb. Additional aggregate and redensification shall be performed until less than 150% of the load test values are achieved. If this cannot be achieved within 2/3 of the pier depth, then the hole shall be reaugered and placed under slurry, or other methods should be used to penetrate to the correct depth.

A price for piers constructed to the specified length and a modulus load test should be provided in the contractor’s base bid. Additionally, unit prices should be provided for additional modulus load tests, additional piers beyond the base bid, casing of holes and additional mobilizations.

February 19, 2015 Page 11 Schnabel Engineering Consultants, Inc.

Spread Footings

The Contractor should exercise care during excavation for spread footings so that as little disturbance as possible occurs at the foundation level. The Contractor should carefully clean loose or soft soils from the bottom of the excavation before placing concrete. A Geotechnical Engineer from our firm should observe footing subgrades prior to concrete placement to evaluate whether subgrade soils are as anticipated in this report.

Footing subgrades needing undercut should be concreted at the elevation of undercut or backfilled to the original design subgrade elevation with lean concrete. We do not recommend open-graded crushed stone backfill since this material provides a path for moisture to reach subgrade soils, resulting in an increased potential for shrink/swell related distress. The Contractor should place footing concrete immediately after excavation of the footing to prevent accumulation of water in the excavation or drying of foundation soils.

The potential for variation of moisture content in foundation soils is probably greatest during construction.

If the moisture content of foundation soils increases or decreases during construction, a moisture-related change in volume will likely occur as these soils return to their natural moisture content. Therefore, prompt placement of concrete, backfilling, and grading are very important for proper foundation performance.

The Contractor should anticipate groundwater during excavation for footings at this site especially in the area of the basement near the location of Boring B-01. We anticipate that pumping from sump pits within the footing excavations can control groundwater.

To protect bearing materials from deteriorating, three-inch mud-mats consisting of lean concrete should be placed over them immediately after excavation and evaluation of spread footing subgrades. Forms may be used if necessary, but less subgrade disturbance is expected if excavations are made to the required dimensions, and concrete is placed against the soil. If footings are formed, the forms should be pulled and the excavation backfilled as soon as possible. Water should not be allowed to pond along the outside of footings for long periods of time.

Site Grading and Earthwork

The test boring data indicate the approximate depth of topsoil based on our visual identification procedures. The depth of stripping needed to provide a suitable base for placement of earthwork may include topsoil and other softer surficial layers. The depth of required stripping should be determined by the excavation Contractor prior to construction using test pits, probes, or other means.

The on-site soils are susceptible to moisture changes, will be easily disturbed, and will be difficult to compact under wet weather conditions. Drying and reworking of the soils are likely to be difficult during periods of wet months. We recommend that the earthwork phases of this project be performed during the warmer, drier times of the year to limit the potential for disturbance of on-site soils.

The soils at this site consist primarily of moderately to highly plastic clays and silts. These soils are moisture sensitive, and will become readily disturbed by construction traffic on exposed surfaces of wet

February 19, 2015 Page 12 Schnabel Engineering Consultants, Inc.

subgrades. We recommend avoiding wet weather site preparation and grading activities. If wet weather work is performed, the quantities of disturbed soils to be excavated can be expected to increase.

Traffic on stripped or undercut subgrades should be limited to reduce disturbance of underlying soils.

Also, using lightweight, track-mounted dozer equipment for stripping will limit the disturbance of underlying soils, and may reduce the undercut volume needed. The Contractor should provide site drainage to maintain subgrades free of water and to avoid saturation and disturbance of the subgrade soils before placing compacted structural fill or moisture barrier material. This site drainage will be important during all phases of the construction work. The Contractor should be responsible for reworking of subgrades and compacted structural fill that were initially considered suitable but were later disturbed by equipment and/or weather.

Grading activities may encounter perched groundwater in the vicinity of Boring B-07, and grading activities may encounter groundwater during excavation for the basement portion of the new building near Boring B-01, based on our observations. Therefore, the Contractor will likely need to provide temporary dewatering such as trenching and/or pumping from sumps to control the surface and/or groundwater.

Engineering Services During Construction

The engineering recommendations provided in this report are based on the information obtained from the subsurface exploration and laboratory testing. However, conditions on the site may vary between the discrete locations observed at the time of our subsurface exploration. The nature and extent of variations between borings may not become evident until during construction.

To account for this variability, we should provide professional observation and testing of subsurface conditions revealed during construction as an extension of our engineering services. These services will also help in evaluating the contractor's conformance with the plans and specifications in accordance with building code requirements. Because of our unique position to understand the intent of the geotechnical engineering recommendations, retaining Schnabel for these services will allow the owner to receive consistent service throughout the project construction.

General Specification Recommendations

An allowance should be established to account for possible additional costs that may be required to construct earthwork and foundations as recommended in this report. Additional costs may be incurred for a variety of reasons including variation of soil between borings, greater than anticipated unsuitable soils, need for borrow fill material, wet on-site soils, obstructions, temporary dewatering, etc.

We recommend that the construction contract include unit prices for scarifying and drying wet and/or loose subgrade soils, and provide an allowance for this work. In addition, the construction contract should include an allowance for undercutting soft or loose, near-surface soils, and replacement with compacted structural fill. Add/deduct unit prices should also be established in the contract so adjustments can be made for the actual volume of materials handled.

The project specifications should indicate the Contractor's responsibility for providing adequate site drainage during construction. Inadequate drainage will most likely lead to disturbance of soils by construction traffic and increased volume of undercut.

February 19, 2015 Page 13 Schnabel Engineering Consultants, Inc.

This report may be made available to prospective bidders for informational purposes. We recommend that the project specifications contain the following statement:

Schnabel Engineering Consultants, Inc., has prepared this geotechnical engineering report for this project. This report is for informational purposes only and is not part of the contract documents. The opinions expressed represent the Geotechnical Engineer’s interpretation of the subsurface conditions, tests, and the results of analyses conducted. Should the data contained in this report not be adequate for the Contractor's purposes, the Contractor may make, before bidding, independent exploration, tests and analyses. This report may be examined by bidders at the office of the Owner, or copies may be obtained from the Owner at nominal charge.

Additional data and reports prepared by others that could have an impact upon the Contractor's bid should also be made available to prospective bidders for informational purposes.

LIMITATIONS

We based the analyses and recommendations submitted in this report on the information revealed by our exploration. We attempted to provide for normal contingencies, but the possibility remains that unexpected conditions may be encountered during construction.

This report has been prepared to aid in the evaluation of this site and to assist in the design of the project.

It is intended for use concerning this specific project. We based our recommendations on information on the site and proposed construction as described in this report. Substantial changes in loads, locations, or grades should be brought to our attention so we can modify our recommendations as needed. We would appreciate an opportunity to review the plans and specifications as they pertain to the recommendations contained in this report, and to submit our comments to you based on this review.

We have endeavored to complete the services identified herein in a manner consistent with that level of care and skill ordinarily exercised by members of the profession currently practicing in the same locality and under similar conditions as this project. No other representation, express or implied, is included or intended, and no warranty or guarantee is included or intended in this report, or other instrument of service.

February 19, 2015 Page 14 Schnabel Engineering Consultants, Inc.

We appreciate the opportunity to be of service for this project. Please call us if you have any questions regarding this report.

Sincerely, SCHNABEL ENGINEERING CONSULTANTS, INC.

Benedictus K. Azumah, PE Senior Staff Engineer

Jeremy L. Mydlinski, PE Senior Associate

BKA:JLM:ms

Figures Appendix A: Subsurface Exploration Data Appendix B: Soil Laboratory Test Data

February 19, 2015 Page 15 Schnabel Engineering Consultants, Inc.

mstory Ben Azumah mstory Jeremy Mydlinski mstory Nate Dumas mstory Ben Azumah

FIGURES

Figure 1: Site Vicinity Map Figure 2: Boring Location Plan Figure 3: Lateral Earth Pressure Diagram

February 19, 2015 Schnabel Engineering Consultants, Inc.

³ 2/5

/20

T his

M ap w as

C rea ted In

Sc hn ab el

En gin ee rin gs Si te Vic ini ty

Ma p A pp lica tio n

NOT TO SCALE

arc gis

COMMUNITY LIVING CENTER EXPANSION

PROJECT NO. 15613010

SITE VICINITY

MAP

FIGURE 1

1201 BROAD ROCK BOULEVARD

Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community Sources: Esri, HERE, DeLorme, USGS, Intermap, increment P Corp., NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, MapmyIndia, © OpenStreetMap

© Schnabel Engineering, 2014. All Rights Reserved.

bazumah Text Box

COMMUNITY LIVING CENTER EXPANSION

1201 BROAD ROCK BOULEVARD

RICHMOND, VIRGINIA

B-01

B-04

B-02

B-03 B-06

B-09

B-12B

B-12A

B-12

B-11A

B-11

B-08, -08A B-05

B-10

B-07

EXISTING COMMUNITY

LIVING CENTER

H U

N T

E R

H

O L M

S

D

I V

E

B-01

B-04

B-02

B-03 B-06

B-09

B-12B

B-12A

B-12

B-11A

B-11

B-08, -08A B-05

B-10

B-07

PROPOSED COMMUNITY

LIVING CENTER EXPANSION

EXISTING COMMUNITY

LIVING CENTER

FF EL = 90.2

H U

N T

H

O L M

S

D

I V

E

WEST HOUSE

EAST HOUSE

COMMUNITY LIVING CENTER EXPANSION

MCGUIRE VA MEDICAL CENTER

1201 BROAD ROCK BOULEVARD

RICHMOND, VIRGINIA

BORING LOCATION

PLAN

15613010

Figure Name: Done:

Project Number: Reviewed:

Figure Number:

Date:

B. AZUMAH

J. MYDLINSKI

FEB 2015

Base Plan Provided by Huelat Davis Healing Design on February 10, 2015.

N

00 50' 100'

SCALE: 1"=50'

LEGEND

APPROXIMATE BORING LOCATION

G

R i c h m o n d

C

L C x p a n s i o n

M c Q u i r e

V

A

S

E

P r o d u c t s

C

A D

B

L P d w g

P

M

COEFFICIENT (B)

0.4

EQUIVALENT

FLUID PRESSURE (A)

50H

BACKFILL

SC OR BETTER

PRESSURE

CONDITION

AT-REST

(BRACED)

0.3 35H

CRUSHED STONE AT-REST

(BRACED)

LOWEST FLOOR OF ADDITION , EL 66.2

AB

q, SURCHARGE

(PSF)

GROUND

SURFACE

H

EARTH PRESSURE RECOMMENDATIONS

FOR BELOW GRADE WALLS

NOT TO SCALE

FIRST FLOOR OF ADDITION, EL 90.2

PERIMETER DRAIN

PANEL DRAIN

(IF NEEDED)

COMMUNITY LIVING CENTER EXPANSION

MCGUIRE VA MEDICAL CENTER

1201 BROAD ROCK BOULEVARD

RICHMOND, VIRGINIA

LATERAL EARTH

PRESSURE DIAGRAM

Figure Name: Done:

Project Number:

Reviewed:

Figure Number:

Date:

B. AZUMAH

J. MYDLINSKI

15613010 FEB 2015

G

R i c h m o n d

C

L C x p a n s i o n

M c Q u i r e

V

A S

E

P r o d u c t s C

A D

F i g u r e

L a t e r a l

E a r t h

P r e s s u r e o n

W a l l s d w g

P

M

APPENDIX A

SUBSURFACE EXPLORATION DATA

Subsurface Exploration Procedures General Notes for Subsurface Exploration Logs Identification of Soil Boring Logs, B-01 through B-12B

SUBSURFACE EXPLORATION PROCEDURES

Test Borings – Hollow Stem Augers

The borings are advanced by turning a continuous flight auger with a center opening of 2¼ or 3¼ inches.

A plug device blocks off the center opening while augers are advanced. Cuttings are brought to the surface by the auger flights. Sampling is performed through the center opening in the hollow stem auger, by standard methods, after removal of the plug. Usually, no water is introduced into the boring using this procedure.

Standard Penetration Test Results

The numbers in the Sampling Data column of the boring logs represent Standard Penetration Test (SPT) results. Each number represents the blows needed to drive a 2-inch O.D., 1⅜-inch I.D. split-spoon sampler 6 inches, using a 140-pound hammer falling 30 inches. The sampler is typically driven a total of 18 or 24 inches. The first 6 inches are considered a seating interval. The total of the number of blows for the second and third 6-inch intervals is the SPT “N value.” The SPT is conducted according to ASTM D1586.

Soil Classification Criteria

The group symbols on the logs represent the Unified Soil Classification System Group Symbols (ASTM D2487) based on visual observation and limited laboratory testing of the samples. Criteria for visual identification of soil samples are included in this appendix. Some variation can be expected between samples visually classified and samples classified in the laboratory.

Pocket Penetrometer Results

The values following “PP=” in the sampling data column of the logs represent pocket penetrometer readings. Pocket penetrometer readings provide an estimate of the unconfined compressive strength of fine-grained soils.

Boring Locations and Elevations

Borings locations were staked by personnel from our office using a hand-held sub-meter accuracy GPS unit. Approximate boring locations are shown on Figure 2. Ground surface elevations at the boring locations were obtained from the site topographic plan and are indicated on the logs. Locations and elevations should be considered no more accurate than the methods used to determine them.

GENERAL NOTES FOR

SUBSURFACE EXPLORATION LOGS

1. Numbers in sampling data column next to Standard Penetration Test (SPT) symbols indicate blows required to drive a 2-inch O.D., 1⅜-inch I.D. sampling spoon 6 inches using a 140 pound hammer falling 30 inches. The Standard Penetration Test (SPT) N value is the number of blows required to drive the sampler 12 inches, after a 6 inch seating interval. The Standard Penetration Test is performed in general accordance with ASTM D1586.

2. Visual classification of soil is in accordance with terminology set forth in “Identification of Soil.”

The ASTM D2487 group symbols (e.g., CL) shown in the classification column are based on visual observations.

3. Estimated water levels indicated on the logs are only estimates from available data and may vary with precipitation, porosity of the soil, site topography, and other factors.

4. Refusal at the surface of rock, boulder, or other obstruction is defined as an SPT resistance of 50 blows for 1 inch or less of penetration.

5. The logs and related information depict subsurface conditions only at the specific…