ATTACHMENT_9_NASA_Instrument_Development_Facility_Geotechnical_Report_-_final.pdf

19955 Highland Vista Dr., Suite 170 Ashburn, Virginia 20147

(703) 726-8030 www.geoconcepts-eng.com

April 10, 2014

Mr. Alexis Smislova, Jr., RA, LEED AP HDR Architecture, Inc.

1101 King Street, Suite 400 Alexandria, VA 22314

Subject: Geotechnical Engineering Report, Instrument

Development Facility, NASA Goddard Flight Center, Greenbelt, Prince George’s County, Maryland (Our 10067.01)

Dear Mr. Smislova:

GeoConcepts Engineering, Inc. (GeoConcepts) is pleased to present the following geotechnical engineering report prepared for the Instrument Development Facility at the NASA Goddard Space Flight Center in Greenbelt, Maryland.

We appreciate the opportunity to serve as your geotechnical consultant on this project. Please do not hesitate to contact me if you have any questions or want to meet to discuss the findings and recommendations contained in the report.

Sincerely, GEOCONCEPTS ENGINEERING, INC.

Paul E. Burkart, PE Principal pburkart@geoconcepts-eng.com

Table of Contents

1.0 Scope of Services

2.0 Site Description and Proposed Construction

3.0 Subsurface Conditions

3.1 Geology

3.2 Stratification

3.3 Groundwater

3.4 Soil Laboratory Test Results

3.5 Seismic Site Classification

4.0 Engineering Analysis

4.1 Spread Footings

4.2 Lower Floor Slabs on Grade

4.3 Lateral Earth Pressures and Subdrainage

4.4 Pavements

4.4.1 Traffic Analyses

4.4.2 Pavement Design Recommendations

4.5 Earthwork

4.6 Infiltration Analysis

4.6.1 Infiltration Test Results

4.6.2 Classification Test Results

4.6.3 Recommended Design Infiltration Rate

5.0 General Limitations

Figure 1: Site Vicinity Map Figure 2: Design Earth Pressures for Loading Dock Walls Figure 3: Design Earth Pressures for Site Retaining Walls Figure 4: Compacted Structural Fill Diagram

Appendix A: Subsurface Investigation Appendix B: Soil Laboratory Test Results Appendix C: Pavement Design Calculations

April 10, 2014 10067.01 Page 2

Based on information provided to us, the proposed construction consists of a new 2-story building with a loading dock, associated at grade pavement areas, and stormwater management/green areas. The proposed building will have a finished floor level at elevation (EL) 226.0. Maximum column and wall loads are 600 kips and 4 kips/ft, respectively.

3.0 Subsurface Conditions

Subsurface conditions were investigated by drilling a total of 12 test borings in the proposed site development area. Test boring logs and a boring location plan are presented in Appendix A of this report.

3.1 Geology

The site is located within the Coastal Plain Physiographic Province of Maryland. The Coastal Plain consists of a seaward thickening wedge of unconsolidated to semi-consolidated sedimentary deposits from the Cretaceous Geologic Period to the Holocene Geologic Epoch. These deposits represent marginal-marine to marine sediments consisting of interbedded sands and clays. The Coastal Plain is bordered to the east by the Atlantic Ocean and to the west by the Piedmont Physiographic Province. The dividing line between the Coastal Plain and the Piedmont is locally referred to as the “Fall Line”. This name comes from the waterfalls that form as a result of the differential erosion that occurs as streams cross the Piedmont/Coastal Plain contact.

Specifically, according to local geologic maps, the site is mapped in the Potomac Group Formation of the Cretaceous geologic period. These soils are known to be highly over-consolidated as a result of the weight of a substantial thickness of overlying soils that have since been eroded away. As a result of over-consolidation, Potomac Group soils have been pre-loaded and are capable of supporting substantial loads.

The subsurface investigation indicated the presence of natural soils consistent with the geology map information provided above.

3.2 Stratification

The subsurface materials encountered have been stratified for purposes of our discussions herein. These stratum designations do not imply that the materials encountered are continuous across the site. Stratum designations have been established to characterize similar subsurface conditions based on material gradations and parent geology. The subsurface materials encountered in the test borings completed at the site have been assigned to the following strata:

Stratum A (Existing Fill) firm to compact, silty sand, poorly graded sand, clayey sand FILL, with gravel, moist, brown, tan, gray, and reddish brown

Stratum B1 (Potomac Group) medium stiff to hard, LEAN CLAY (CL), with various amounts of sand, moist, brown, tan, gray, pink, and brownish gray

Stratum B2 (Potomac Group) firm to compact, POORLY GRADED SAND (SP-SM) with silt, silty SAND (SM), clayey SAND (SC), moist, brown, tan, gray, reddish brown, orange, and pink

The two letter designations included in the strata descriptions presented above and on the test boring logs represent the Unified Soil Classification System (USCS) group symbol and group name for the samples based on laboratory testing per ASTM D-2487 and visual classifications per ASTM D-2488. It should be noted that visual classifications per ASTM D-2488 may not match classifications determined by laboratory testing per ASTM D-2487.

April 10, 2014 10067.01 Page 5

4.2 Lower Floor Slabs on Grade

Lower floor slabs supported by firm to compact existing soils or new compacted fill are considered feasible at the site. All debris and soft soils near the final floor slab subgrade as a result of construction operations should be stripped and removed prior to placement of underfloor stone. A 4-inch minimum thickness of washed gravel or crushed stone meeting the requirement of AASHTO No. 57 should be placed below the floor slab on grade to serve as a capillary break. An impermeable plastic membrane should be placed on top of the crushed stone layer to assist as a moisture barrier. Special attention should be given to the surface curing of the slab in order to minimize uneven drying of the slab and associated cracking.

Underfloor subdrainage is not recommended since groundwater is expected to be below the lower floor level.

We recommend that mesh (fiber or welded wire fabric) reinforcement be included in the design of the floor slab to minimize the development of any shrinkage cracks near the surface of the slab. If welded wire fabric is used, the mesh should be located in the top half of the slab.

4.3 Lateral Earth Pressures and Subdrainage

Loading dock walls and site retaining walls should be designed to withstand lateral earth pressures. An equivalent fluid pressure of 60H (psf) should be used for design of loading dock walls and 42H (psf) for design of site retaining walls, where H refers to the height of the wall. The design should account for any surcharge loads within a 45 degree slope from the base of the wall. Retaining walls may be designed to include a passive equivalent fluid pressure of 375D (psf), where D represents the depth of wall embedment below the exposed wall face. The upper 1.5 feet of soil at the base of retaining walls should not be included in the design of passive soil resistance. A coefficient of friction of 0.35 may be used for sliding resistance at the soil/concrete interface. Recommended lateral earth pressure diagrams for use in the design of loading dock walls and site retaining walls are presented as Figures 2 and 3, respectively, at the end of this report.

Hydrostatic pressures are not included in the lateral earth pressure diagrams assuming the use of relatively granular or free draining backfill, and perimeter subdrainage (weepholes) at the base of walls below grade.

Recommended subdrainage for loading dock and site retaining walls are presented on Figures 2 and 3, respectively, at the end of this report. Recommendations for backfill against walls below grade are presented in Section 4.5 of this report.

4.4 Pavements

Pavement subgrades are expected to consist of firm to compact existing soils or new compacted fill. These materials are generally considered suitable for support of the planned roadways and parking areas.

However, where pavement subgrades consist of existing fill, we recommend budgeting for undercutting the existing fill to a depth of at least 2 feet and backfilling with new compacted fill. The decision to undercut the existing fill should be based on a thorough proofroll of the pavement subgrades under the observation of the geotechnical engineer.

Based on the California Bearing Ratio (CBR) test results for the materials expected at pavement subgrades, a preliminary design CBR value of 3 is recommended for pavement design purposes. The design CBR value of 3 represents the average of the two CBR test results reduced by two-thirds. If fill placed at the site is generated from off-site borrow areas, the actual CBR value for the pavement subgrades may be significantly different from the preliminary value presented herein. Therefore, CBR tests should be performed on the in-place subgrade after rough grading and installation of utilities within roadways. Final pavement sections should be based on CBR tests taken on subgrade soils at the time of construction. Concrete pavements should be utilized in loading dock areas and for dumpster pads.

April 10, 2014 10067.01 Page 8 course has been increased to account for the heavier-loaded construction traffic. We suggest that placement of the asphalt surface course not occur until all the major construction has been completed for pavement areas subjected to construction traffic. To minimize damage to light duty pavement areas during and after construction, consideration should be given to restricting access by construction and any future commercial (non-passenger vehicle) traffic onto the light duty pavement areas, where possible.

The overall grading design should include suitable storm inlets and diversion structures for collecting surface runoff and to limit excessive ponding on paved surfaces. Specific surface drainage recommendations are beyond the scope of our services.

4.5 Earthwork

Fill will be required for site grading in building and pavement areas, and as backfill against walls below grade. Unsuitable existing fill, soft or loose natural soils, organic material, and rubble should be stripped to approved subgrades as determined by the geotechnical engineer. Topsoil, asphalt, and gravel base depths presented on the boring logs should not be considered as stripping depths, as topsoil, asphalt, and gravel base depths may vary widely across the site. Stripping depths will probably extend to greater depths than the topsoil depths indicated herein due to the presence of minor amounts of organics, roots, and other surficial materials that will require removal as a part of the stripping operations. In addition, seasonal soil moisture variations can affect stripping depths. In general, less stripping may occur during summer months when drier weather conditions can be expected. The depth of required stripping should be determined prior to construction by the excavation contractor using test pits, probes, or other means that the contractor wishes to employ, and this determination should be the responsibility of the excavation contractor. All subgrades should be proofrolled with a minimum 20 ton, loaded dump truck or suitable rubber tire construction equipment approved by the geotechnical engineer, prior to the placement of new fill.

Fill material should be placed in lifts not exceeding 8 inches loose thickness, with fill materials compacted by hand operated tampers or light compaction equipment placed in maximum 4-inch thick loose lifts. Fill should be compacted at +/- 2% of the optimum moisture content to at least 95 percent of the maximum dry density per ASTM D-698, except that fill placed in building areas should be compacted to at least 98 percent of the maximum dry density per ASTM D-698.

Materials used for compacted fill for support of footings, floor slabs, and pavements should consist of soils classifying SC, SM, SP, SW, GC, GM, GP, or GW per ASTM D-2487, with a maximum dry density greater than 105 pcf. Materials used for backfill against walls below grade should consist of soils classifying SM, SP, SW, GM, GP, or GW, with a liquid limit and plasticity index less than 40 and 15, respectively. It is expected that the generally granular Stratum B2 soils excavated at the site will be suitable for re-use as fill based on classification. The Stratum A existing fill was also generally granular classification but may not be suitable for re-use as new compacted fill due to deleterious man-made materials in the fill. In addition, drying of excavated soils by spreading and aerating may be necessary to obtain proper compaction. This may not be practical during the wet period of the year. Accordingly, earthwork operations should be planned for early Spring through late Fall, when drier weather conditions can be expected. Individual borrow areas, both from on-site and off-site sources, should be sampled and tested to verify classification of materials prior to their use as fill.

Fill materials should not be placed on frozen or frost-heaved soils, and/or soils that have been recently subjected to precipitation. All frozen or frost-heaved soils should be removed prior to continuation of fill operations. Borrow fill materials should not contain frozen materials at the time of placement.

Compaction equipment that is compatible with the soil type used for fill should be selected. Theoretically, any equipment type can be used as long as the required density is achieved; however, sheepsfoot roller equipment are best suited for fine-grained soils and vibratory smooth drum rollers are best suited for granular soils. Ideally, a smooth drum roller should be used for sealing the surface soils at the end of the day or prior to upcoming rain events. In addition, compaction equipment used adjacent to walls below

Appendix A Subsurface Investigation Subsurface Investigation Procedures (1 page)

Identification of Soil (1 page)

Test Boring Notes (1 page)

Test Boring Logs (12 pages)

Boring Location Plan, Figure 5 (1 page)

Subsurface Investigation Procedures

1. Test Borings – Hollow Stem Augers The borings are advanced by turning an auger with a center opening of 2-¼ 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.

2. Standard Penetration Tests Standard penetration tests are performed by driving a 2 inch O.D., 1-⅜ inch I.D. sampling spoon with a 140-pound hammer falling 30 inches, according to ASTM D-1586. After an initial 6 inches penetration to assure the sampling spoon is in undisturbed material, the number of blows required to drive the sampler an additional 12 inches is generally taken as the N value. In the event 30 or more blows are required to drive the sampling spoon the initial 6 inch interval, the sampling spoon is driven to a total penetration resistance of 100 blows or 18 inches, whichever occurs first. The sampling operation is terminated after a total of 50 hammer blows and the depth of penetration is recorded.

3. Test Boring Stakeout The test boring stakeout was provided by GeoConcepts personnel using available site plans. Ground surface elevations were estimated from topographic information. If the risk related to using approximate boring locations and elevations is unacceptable, we recommend an as-drilled survey of boring locations and elevations be completed by a licensed surveyor.

Identification of Soil I. DEFINITION OF SOIL GROUP NAMES ASTM D-2487 Symbol Group Name

Coarse-Grained Soils More than 50% retained on No. 200 sieve

Gravels More than 50% of coarse fraction retained on No. 4 sieve

Clean Gravels Less than 5% fines

GW WELL GRADED GRAVEL

GP POORLY GRADED GRAVEL

Gravels with Fines More than 12% fines

GM silty GRAVEL GC clayey GRAVEL

Sands 50% or more of coarse fraction passes No. 4 sieve

Clean Sands Less than 5% fines

SW WELL GRADED SAND

SP POORLY GRADED SAND

Sands with fines More than 12% fines

SM silty SAND SC clayey SAND

Fine-Grained Soils 50% or more passes the No. 200 sieve

Silts and Clays Liquid Limit less than

Inorganic CL LEAN CLAY

ML SILT

Organic OL ORGANIC CLAY

ORGANIC SILT

Silts and Clays Liquid Limit 50 or more

Inorganic CH FAT CLAY

MH ELASTIC SILT

Organic OH ORGANIC CLAY

ORGANIC SILT

Highly Organic Soils Primarily organic matter, dark in color, and organic odor PT PEAT

II. DEFINITION OF MINOR COMPONENT PROPORTIONS

Minor Component Approximate Percentage of Fraction by Weight Gravelly, Sandy (adjective) 30% or more coarse grained Sand, Gravel (with) 15% to 29% coarse grained Silt, Clay (with) 5% to 12% fine grained

III. GLOSSARY OF MISCELLANEOUS TERMS

SYMBOLS Unified Soil Classification Symbols are shown above as group symbols. Use “A” Line Chart for laboratory identification. Dual symbols are used for borderline classification.

BOULDERS & COBBLES Boulders are considered pieces of rock larger than 12 inches, while cobbles range from 3 to 12 inches.

DISINTEGRATED ROCK Residual rock material with a standard penetration test (SPT) resistance between 60 blows per foot and refusal.

ROCK Rock material with a standard penetration test (SPT) resistance of 100 blows for 2 inches or 50 blows for 0 inches, or less penetration DECOMPOSED ROCK Residual rock material exhibiting rock-like properties that can be excavated by backhoe equipment.

Similar to Disintegrated Rock, but cannot be classified as such because SPT N-Values were not obtained.

ROCK FRAGMENTS Angular pieces of rock, distinguished from rounded transported gravel, which have separated from original vein or strata and are present in a soil matrix.

QUARTZ A hard silicate mineral often found in residual soils. Only used when describing residual soils.

CEMENTED SAND Usually localized rock-like deposits within a soil stratum composed of sand grains cemented by calcium carbonate, iron oxide, or other minerals. Commonly encountered in Coastal Plain sediments, primarily in the Potomac Group sands (Kps).

MICA A plate-like phyllosilicate mineral found in many rocks, and in residual or transported soil derived there from.

ORGANIC MATERIALS

(Excluding Peat)

Topsoil - Surface soils that support plant life and contain organic matter.

Lignite - Hard, brittle decomposed organic matter with low fixed carbon content (a low grade of coal).

FILL Man made deposit containing soil, rock, and other foreign matter.

PROBABLE FILL Soils which contain no visually detected foreign matter but which are suspect with regard to origin.

LAYERS ½ to 12 inch seam of minor soil component.

COLOR Two most predominant colors present should be described.

MOISTURE CONDITIONS Wet, moist, or dry to indicate visual appearance of specimen.

Test Boring Notes

1. Classification of soil is by visual inspection and is in accordance with the Unified Soil Classification

System.

2. Estimated groundwater levels are indicated on the logs. These are only estimates from available data and may vary with precipitation, porosity of soil, site topography, etc.

3. Sampling data presents standard penetrations for 6-inch intervals or as indicated with graphic representations adjacent to the sampling data.

4. The logs and related information depict subsurface conditions at the specific locations and at the particular time when drilled. Soil conditions at other locations may differ from conditions occurring at the test locations. Also, the passage of time may result in a change in the subsurface conditions at the test locations.

5. The stratification lines represent the approximate boundary between soil types as determined in the sampling operation. Some variation may be expected vertically between samples taken. The soil profile, groundwater level observations and penetration resistances presented on the logs have been made with reasonable care and accuracy and must be considered only an approximate representation of subsurface conditions to be encountered at the particular location.

Appendix B Soil Laboratory Test Results Moisture Density Relationship Test Data (2 pages)

CBR Test Data (2 pages)

Texture Analysis (1 page)

Appendix C Pavement Design Calculations Flexible Pavement – Light Duty Section (1 page)

Flexible Pavement – Heavy Duty Section (1 page)

Rigid Pavement (2 pages)

1993 AASHTO Pavement Design

DARWin Pavement Design and Analysis System

A Proprietary AASHTOWare Computer Software Product

GeoConcepts

Flexible Structural Design Module

Light Duty Pavement Section

Flexible Structural Design

18-kip ESALs Over Initial Performance Period 54,910 Initial Serviceability 4 Terminal Serviceability 2.5 Reliability Level 85 % Overall Standard Deviation 0.49 Roadbed Soil Resilient Modulus 4,500 psi Stage Construction 1

Calculated Design Structural Number 2.58 in

Rigorous ESAL Calculation

Performance Period (years) 20 Two-Way Traffic (ADT) 1,600 Number of Lanes in Design Direction 1 Percent of All Trucks in Design Lane 50 % Percent Trucks in Design Direction 100 %

Vehicle Class

Percent of

ADT

Annual

Growth

Average Initial Truck Factor

(ESALs/ Truck)

Annual % Growth in

Truck Factor

Accumulated 18-kip ESALs over Performance Period

1 98 0 0.0002 0 1,145 4 2 0 0.46 0 53,765

Total 100 - - - 54,910

Growth Simple

Total Calculated Cumulative ESALs 54,910

Specified Layer Design

Layer

Material Description

Struct Coef.

(Ai)

Drain Coef.

(Mi)

Thickness (Di)(in)

Width

(ft)

Calculated

SN (in) 1 HMA Superpave 9.5mm Surface 0.44 1 1.5 - 0.66 2 HMA Superpave 19.0mm Base 0.4 1 3 - 1.20 3 Graded Aggregate Subbase 0.12 1 6 - 0.72

Total - - - 10.50 - 2.58

Flexible Structural Design Module

Heavy Duty Pavement Section

Flexible Structural Design

18-kip ESALs Over Initial Performance Period 552,842 Initial Serviceability 4 Terminal Serviceability 2.5 Reliability Level 85 % Overall Standard Deviation 0.49 Roadbed Soil Resilient Modulus 4,500 psi Stage Construction 1

Calculated Design Structural Number 3.84 in

Performance Period (years) 20 Two-Way Traffic (ADT) 2,000 Number of Lanes in Design Direction 1 Percent of All Trucks in Design Lane 50 %

Growth

Average Initial Truck Factor

(ESALs/ Truck)

Annual % Growth in

Truck Factor

Accumulated 18-kip ESALs over Performance Period

1 90 0 0.0002 0 1,315 3 5 0 0.46 0 168,015 9 5 0 1.05 0 383,513

Total 100 - - - 552,842

Total Calculated Cumulative ESALs 552,842

Specified Layer Design

Struct Coef.

(Ai)

Drain Coef.

(Mi)

(Di)(in)

Width

Calculated

SN (in) 1 HMA Superpave 9.5mm Surface 0.44 1 2 - 0.88 2 HMA Superpave 19.0mm Base 0.4 1 6 - 2.40 3 Graded Aggregate Subbase 0.12 1 6 - 0.72

Total - - - 14.00 - 4.00

Rigid Structural Design Module

Loading Dock

Rigid Structural Design

Pavement Type JRCP 18-kip ESALs Over Initial Performance Period 2,438,044 Initial Serviceability 4.5 Terminal Serviceability 2.8 28-day Mean PCC Modulus of Rupture 650 psi 28-day Mean Elastic Modulus of Slab 5,000,000 psi Mean Effective k-value 150 psi/in Reliability Level 90 % Overall Standard Deviation 0.39 Load Transfer Coefficient, J 2.8 Overall Drainage Coefficient, Cd 1

Calculated Design Thickness 7.84 in

Performance Period (years) 30 Two-Way Traffic (ADT) 250 Number of Lanes in Design Direction 1 Percent of All Trucks in Design Lane 100 %

Growth

Average Initial Truck Factor

(ESALs/ Truck)

Annual % Growth in

Truck Factor

Accumulated 18-kip ESALs over Performance Period

4 70 0 0.59 0 1,131,362 9 30 0 1.59 0 1,306,682

Total 100 - - - 2,438,044

Total Calculated Cumulative ESALs 2,438,044

Layer Information

(in)

One Dir Width

(ft)

1 JRCP 7.8385076 -

2 VDOT #21-A 8 -

(in)

One Dir Width

Total - 15.84 -

texture analysis