ATTACHMENT I - SPECS APP B.pdf

V47 Breakwater Pier eProject No. 1605379 Naval Station Norfolk, Norfolk, VA

APPENDIX 'B'

GEOTECHNICAL ENGINEERING REPORT

V47 Breakwater Pier eProject No. 1605379 Naval Station Norfolk, Norfolk, VA

THIS PAGE INTENTIONALLY LEFT BLANK

REPORT OF

SUBSURFACE

EXPLORATION

AND

GEOTECHNICAL

ENGINEERING

SERVICES

PREPARED FOR:

5465 Greenwich Road · Virginia Beach, VA 23462 Phone: (757)-518-1703 www.getsolutionsinc.com

V-47 Breakwater Pier

Norfolk, Virginia

G E T Project No.: VB20-265G

February 15, 2021 (Revised March 5, 2021) hschilling Stamp hschilling Stamp

5465 Greenwich Road · Virginia Beach, VA 23462 · Phone: (757)-518-1703 · Fax: (757)-518-1704 info@getsolutionsinc.com

February 15, 2021 (Revised March 5, 2021)

TO: Moffatt & Nichol 101 W Main St. #800 Norfolk, VA 23510

Attn: Mr. William W. Wheaton, PE

RE: Report of Subsurface Exploration and Geotechnical Engineering Services V-47 Breakwater Pier Naval Station Norfolk, Virginia G E T Report No.: VB20-265G

Dear Mr. Wheaton:

In compliance with your instructions, we have completed our Subsurface Exploration and Geotechnical Engineering Services for the above referenced project. The results of this study, together with our recommendations, are presented in this report.

Often, because of design and construction details that occur on a project, questions arise concerning subsurface conditions. G E T Solutions, Inc. would be pleased to continue its role as Geotechnical Engineer during the project implementation.

We appreciate the opportunity to work with you on this project. We trust that the information contained herein meets your immediate need, and should you have any questions or if we could be of further assistance, please do not hesitate to contact us.

Respectfully Submitted, G E T Solutions, Inc.

Haleigh Schilling Project Geologist

Maria E. Murdock, P.E. Bruce R. Spiro, P.E.

Senior Project Engineer Principal Engineer VA Reg. # 039988 VA Reg. # 015791

Copies: (1) Client

TABLE OF CONTENTS

V-47 Breakwater Pier Naval Station Norfolk, Norfolk, Virginia G E T Report No.: VB20-265G

1.0 PROJECT INFORMATION

1.1 Project Authorization

1.2 Project Site Location and Description

1.3 Purpose and Scope of Services

2.0 FIELD AND LABORATORY PROCEDURES

2.1 Field Exploration

2.2 Field and Laboratory Testing

2.2.1 Soil Classification and Index Testing

2.2.2 Triaxial Testing

3.0 SITE AND SUBSURFACE CONDITIONS

3.1 Site Geology

3.2 Recent Land Reclamation and Site Development

3.3 Subsurface Soil Conditions

3.4 Groundwater Discussion

4.0 EVALUATIONS AND RECOMMENDATIONS

4.1 Clearing and Grading

4.2 Structural Fill and Placement

4.3 Suitability of On-site Soils

4.4 Below Grade Parameters for Breakwater Concrete Sheet Piles

4.5 Below Grade Parameters for Bulkhead

4.6 Axial Compression Capacity Recommendations-Breakwater Pier

4.6.1 Pile Drivability Considerations

4.6.2 Negative Side Friction Discussion

4.6.3 Test Piles

4.6.4 Dynamic Testing

4.6.5 Establishing Pile Driving Criteria

4.6.6 Allowable Driving Stresses

4.6.7 Hammer Types and Energies

4.6.8 Driven Pile Installation Monitoring

4.6.9 Pile Group Settlement

4.7 Buried Utility Lines

5.0 CONSTRUCTION CONSIDERATIONS

5.1 Anticipated Excavation Characteristics

5.2 Excavation Stability

5.3 Dewatering

6.0 REPORT LIMITATIONS

APPENDIX I BORING LOCATION PLAN

APPENDIX II CLASSIFICATION SYSTEM FOR SOIL EXPLORATION

APPENDIX III SUMMARY OF LABORATORY CLASSIFICATION RESULTS

APPENDIX IV BORING LOG

APPENDIX V TRIAXIAL TEST RESULTS

APPENDIX VI USGS 1978 GEOOGY OF THE NORFOLK NORTH QUADRANGLE

APPENDIX VII SUPPORTING CALCULATIONS

APPENDIX VIII HISTORIC GEOTECHNICAL INFORMATION

Report of Subsurface Exploration and Geotechnical Engineering Services February 15, 2021 V-47 Breakwater Pier (Revised March 5, 2021)

1.0 PROJECT INFORMATION

1.1 Project Authorization

G E T Solutions, Inc. has completed our subsurface exploration and geotechnical engineering services for the proposed V-47 Breakwater Pier project located at Naval Station Norfolk in Norfolk, Virginia. The geotechnical engineering services were conducted in general accordance with the scope presented in G E T Proposal No. PVB20-441G revised on September 11, 2020 and SAES (Contract No. N40085-18-D-1100, W.O. #1605379, Rev17) dated February 2020. Authorization to proceed with our services was received from the client in the form of an executed Master Services Subcontract Agreement dated September 30, 2020.

1.2 Project Site Location and Description

The project site is located within the V-47 Squadron compound adjacent to Willoughby Bay within Naval Station Norfolk, Virginia. The proposed construction will consist of the following:

1. An approximately 20- by 200-foot concrete breakwater pier to be supported on a deep foundation system. The deep foundation system will consist of either Square, Precast, Prestressed Concrete (SPPC) or steel HP piles. Concrete sheet piles will be jetted on the northern side of the pier for protective breakwater services. The pier will be designed to provide for the mooring and berthing of various watercraft during calm weather.

2. Repairs to the bulkhead about 50 feet on either side of the pier. The original bulkhead was constructed with steel sheet pile in 1933, and last repaired in 2001 by adding composite sheet piling in front of the existing steel sheet pile. The eastern side of the bulkhead will also be designed to provide for the mooring and berthing of watercraft.

3. Buried electrical and water service to the pier for services stations which will provide power, and water to those utilizing the pier.

4. Buried utility lines throughout the complex. Utility lines are expected to bear at about 6 to 8 feet below existing grades.

Top of Pier and existing site grades are about 7 ft NAVD 88. The mudline at the location of the proposed pier is roughly -11 ft NAVD 88. Approximately 5 feet of scour has been calculated to occur at the proposed pier. Design site grades are expected to remain the same as current grades. Elevations are based on SAES Attachment #2, sheet S-101 provided by the client. A prior geotechnical exploration and evaluation was performed in the immediate vicinity of the proposed pier (GET Solutions, Inc. report VB08-190G, dated June 19, 2008). The data collected during this prior study will be used in the current evaluation of the site. A plan depicting the proposed construction is provided in Figure 1. A site vicinity plan based on the 7.5 Minute Series Norfolk North Quadrangle (2019) is provided in Figure 2.

Figure 1: Proposed Construction

From SAES Attachment #2, Sheet S-001

Figure 2: Site Vicinity

USGS 2019, Bowers Hill Quadrangle, Virginia – 7.5-Minute Series

If any of the noted information is incorrect or has changed, please inform G E T Solutions, Inc. so that we may amend the recommendations presented in this report, if appropriate.

1.3 Purpose and Scope of Services

The purpose of this study was to provide evaluations and recommendations based on our findings in this exploration as well as historic geotechnical information in the vicinity of the project (Report VB08-190G P223V BRAC V-47 Building Renovations for Combat Craft, dated June 19, 2008, provided by NAVFAC). Sections of this prior report are provided in Appendix VIII for reference.

Additionally, historical topographic and geologic maps of the site were reviewed. The purpose of this report is to provide engineering assessments for the following items:

1) General assessment of the soils revealed by our borings performed at the project site.

2) General location and description of potentially deleterious material encountered in the borings that may interfere with construction progress or structure performance, including existing fills or surficial/subsurface organics.

3) Soil subgrade preparation, including stripping, grading and compaction. Engineering criteria for placement and compaction of approved structural fill material.

4) Construction considerations for back-fill placement for utility work behind the bulkhead.

5) Evaluation of the on-site soils for re-use as structural fill.

6) Feasibility of utilizing a deep foundation system of 20-inch Square, Precast, Prestressed Concrete (SPPC), 24-inch SPPC, or HP-14 Steel piles to support the pier.

7) Recommendations for prestressed concrete sheet piling to form the breakwater side of the pier. Estimated soil parameters (unit weights, Ko, Ka, Kp, friction angle, cohesion, soil modulus(k) and strain parameters(E50)) are provided for the lateral analysis. Axial capacities are provided for 16-inch thick concrete sheet pile sections.

8) Estimated soil parameters (unit weights, Ko, Ka, Kp, friction angle and cohesion) are provided for the lateral analysis evaluation for the existing bulkhead, 50 feet on either side of the new pier.

9) Scour impact on the structural components of the project.

10) Based on discussions with the client, any pavement that has been disturbed due to construction or utility installation must be replaced to match the existing pavement section in depth and type of materials. As such, pavement recommendations are not provided in this report, but can be provided upon request.

2.0 FIELD AND LABORATORY PROCEDURES

2.1 Field Exploration

The field exploration program was coordinated with the Waterfront Operations Manager to minimize the impact on Naval operations. G E T Solutions, Inc. met with the Waterfront Operations Manager, reviewed security requirements and established a schedule for performing the work.

G E T Solutions, Inc. notified the client and applicable Base personnel of all field activities prior to mobilizing to the site. Additionally, clearance from VA811 was obtained prior to drilling and a private subsurface utility locator was subcontracted to verify the presence of existing buried utility lines in the vicinity of the proposed exploration locations. An Activity Hazard Analysis document was prepared in accordance with the A-E Safety Plan and signed by all personnel on site before beginning drilling activities. To explore the general subsurface soil types, one (1) 100-foot deep SPT boring (designated as 20B-01) was drilled within the vicinity of the proposed bulkhead. The test location was verified with the client prior to the field activities.

Standard Penetration Tests (SPT) were performed in the field in general accordance with ASTM D1586. The tests were performed continuously from the existing ground surface to a depth of 12 feet, and at 5-foot intervals thereafter starting at a depth of 13 feet. The SPT soil samples were obtained with a standard 1.4” I.D., 2” O.D., 30” long split-spoon sampler. The sampler was driven with blows of a 140 lb. hammer falling 30 inches, using an automatic hammer. The number of blows required to drive the sampler each 6-inch increment of penetration was recorded and is shown on the boring logs. The sum of the second and third penetration increments is termed the SPT N-value (uncorrected for automatic hammer and overburden pressure). A representative portion of each disturbed split-spoon sample was collected with each SPT, placed in a glass jar, sealed, labeled, and returned to our laboratory for review.

The location of the SPT boring was staked in the field by a representative of G E T Solutions, Inc. using a hand-held measurement device. The approximate test location is shown on the attached “Boring Location Plan” which includes locations from the previous exploration for reference (Appendix II).

2.2 Field and Laboratory Testing

Soil testing provided by G E T Solutions, Inc. was performed in accordance with American Society for Testing and Materials (ASTM) standards. All soils and materials tests were performed in our AASHTO re:source (formally AMRL) and US Army Corps of Engineers certified Virginia Beach laboratory.

2.2.1 Soil Classification and Index Testing

Representative portions of all soil samples collected during drilling operations were labeled, preserved and transferred to our laboratory in accordance with ASTM D4220 for classification and analysis. Soil descriptions on the boring logs are provided using visual-manual methods in general accordance with ASTM D2488 using the Unified Soil Classification System (USCS). Soil samples that were selected for index testing were classified in general accordance with ASTM D2487. It should be noted that some variation can be expected between samples classified using the visual-manual procedure (ASTM D2488) and the USCS (ASTM D2487). A summary of the soil classification system is provided in Appendix II.

Representative split-spoon soil samples were selected and subjected to natural moisture, #200 sieve wash, and Atterberg Limits testing in order to corroborate the visual classification. These test results are presented in Appendix III and on the soil test boring log provided in Appendix IV.

2.2.2 Triaxial Testing

Consolidated-Undrained Triaxial Compression tests (ASTM D4767) were performed on the soil specimens extracted from the Shelby tube samples at our Virginia Beach laboratory. The test results are presented in Table I and the comprehensive test results are provided in Appendix V.

Table I- Triaxial Test Results

Boring No.

Depth (Ft)

USCS

Classification

Angle of Internal Friction Φ(1) (deg.)

Cohesion(1) c (psf)

20B-01 20-22 CH Φ’=20.7

Φ=9.9 c’=238 c=290

20B-01 30-32 CH Unable to extract enough sample from tube to perform test.

Note(s): Total and effective parameters are provided in the table. Effective is presented with a prime (‘) next to the parameter.

3.0 SITE AND SUBSURFACE CONDITIONS

3.1 Site Geology

The project site lies within a major physiographic province called the Atlantic Coastal Plain.

Numerous transgressions and regressions of the Atlantic Ocean have deposited marine, lagoonal, and fluvial (stream lain) sediments. The regional geology is very complex, and generally consists of interbedded layers of varying mixtures of sands, silts and clays. Based on our review of existing geologic and soil boring data, the geologic stratigraphy encountered in our subsurface explorations generally consisted of marine deposited Sands, Silts and Clays.

The Yorktown Formation is one of the six stratigraphic units of the Coastal Plain. This formation consists of green-gray, over-consolidated clay and sand with marine shell fragments; it provides a suitable bearing stratum for pile support. Yorktown Formation soils were recovered from the SPT boring location below a depth of 58 feet.

3.2 Recent Land Reclamation and Site Development

In order to obtain information regarding historical land use of the project site and its vicinity, we reviewed the 1978 map of the Geology of the Norfolk North Quadrangle, Virginia, topographic plans and aerial photographs. From this review, it appears that the project site consists of man-made fill land. A copy of a portion of the referenced map is provided in Appendix VI.

3.3 Subsurface Soil Conditions

For the purposes of this report, the subsurface soils have been divided into three (3) strata based on their classifications. A brief description of the subsurface soils conditions encountered at the SPT boring location is presented in Table II.

Table II – Subsurface Soil Conditions

Average Depth Stratum Description Ranges of

SPT(1) N-Values to

0.01 Surficial 1 inch of Topsoil –

0.01 to

18.8

UNCONTROLLED

FILL SAND (SP) with varying amounts of Silt 3 - 10

18.8 to

39.8 I CLAY (CH, CL) and Organic CLAY (OH) with

varying amounts of Sand and Silt WOH(2) - 7

39.8 to

II SAND (SC, SM) with varying amounts of Clay 2 - 3 to

III YORKTOWN (SC) with varying amounts of Silt, Clay and marine shell fragments. 10 - 19

Note(s): (1) SPT = Standard Penetration Test, N-Values in Blows-per-foot (uncorrected)

(2) WOH=Weight-of-Hammer

The subsurface descriptions are of a generalized nature provided to highlight the major soil strata encountered. The records of the subsurface exploration are included in Appendix IV (Boring Log sheet) which should be reviewed for specific information as to the individual boring. The stratifications shown on the records of the subsurface exploration represent the conditions only at the actual boring location. The stratifications represent the approximate boundary between subsurface materials and the transition may be gradual.

3.4 Groundwater Discussion

The initial groundwater-level was recorded at the land SPT boring location as observed through the relative wetness of the recovered soil samples during the drilling operations, and upon the completion of the boring. The initial groundwater level was measured to occur at a depth of approximately 10 feet below the existing site grades. The borehole was backfilled upon completion for safety considerations.

The soils encountered within boring at the presumed groundwater level consisted of granular soils; thus, drilling fluids (bentonite and water) were introduced into the borehole during the drilling operations to prevent cave-ins from occurring, impairing the ability to accurately determine the groundwater level. Therefore, the reported initial groundwater level may not be indicative of the static groundwater level but should be reflective of the immediately adjacent water body and subject to tidal variations.

Groundwater conditions will vary with environmental variations and seasonal conditions, such as the frequency and magnitude of rainfall patterns, as well as man-made influences, such as existing swales, drainage ponds, underdrains and areas of covered soil (paved parking lots, sidewalks, etc.). Seasonal groundwater fluctuations of 2 feet are common in the project’s area;

however, greater fluctuations have been documented. We recommend that the contractor determine the actual groundwater levels at the time of the construction to determine groundwater impact on the construction procedures, if necessary.

4.0 EVALUATIONS AND RECOMMENDATIONS

Our recommendations are based on the previously discussed project information, our interpretation of the soil test borings and laboratory data, and our observations during our site reconnaissance. If the proposed construction should vary from what was described, we request the opportunity to review our recommendations and make any necessary changes. Supporting calculations for the geotechnical evaluations are provided in Appendix VII.

4.1 Clearing and Grading

The proposed construction areas should be cleared by means of removing topsoil, asphalt, concrete or any otherwise unsuitable materials. It is estimated that a cut of up to 3 inches in depth will be required to remove the topsoil materials and a cut of 4 to 13 inches (typically 4 to 8 inches) will be required to remove the concrete and asphalt materials. This cut is expected to extend deeper in isolated areas to remove deeper deposits of unsuitable soils which become evident during the clearing. It is recommended that the clearing operations extend laterally at least 5 feet beyond the perimeter of the proposed construction areas.

To reduce the potential for subgrade improvements (undercutting due to saturated soils in conjunction with heavy construction traffic), it is recommended that the grading operations be performed during the drier months of the year (historically April through November). This should minimize these potential problems, although they may not be eliminated. If grading is attempted during the winter months, undercutting of wet soils should be anticipated. However, during the drier months of the year, wet soils could be dried by discing or implementing other drying procedures to achieve moisture contents necessary to achieve adequate degrees of compaction.

The site should be graded to enhance surface water runoff to reduce the ponding of water.

Ponding of water often results in softening of the near-surface soils. In the event of heavy rainfall within areas to receive fill, we recommend that the grading operations cease until the site has had a chance to dry.

4.2 Structural Fill and Placement

Any material to be used for structural fill should be evaluated and tested by an independent testing laboratory prior to placement to determine if they are suitable for the intended use. Suitable structural fill material should consist of sand or gravel containing less than 25% by weight of fines (SP, SM, SW, GP, GW - with dimensions not to exceed 2 inches in diameter), having a Liquid Limit less than 20 and Plastic Limit less than 6, and should be free of rubble, organics, clay, debris and other unsuitable material.

All structural fill should be compacted to a dry density of at least 95% of the Modified Proctor maximum dry density, in accordance with ASTM Specification D 1557. The moisture content of the structural fill should be within +/- 2% of the optimum moisture content at the time of placement.

In general, the compaction should be accomplished by placing the fill in maximum 8 to 10-inch loose lifts and mechanically compacting each lift to at least the specified minimum dry density. A qualified inspector should perform field density tests on each lift as necessary to assure that adequate compaction is achieved.

Backfill material in utility trenches within the construction areas should consist of structural fill (as previously described) and should be compacted to at least 93% of ASTM Specification D 1557.

This fill should be placed in 4-to-6-inch loose lifts when hand compaction equipment is used.

If applicable, care should be used when operating the compactors near existing structures to avoid transmission of the vibrations that could cause settlement damage or disturb occupants. In this regard, it is recommended that the vibratory roller remain at least 25 feet away from existing structures; these areas should be compacted with small, hand-operated compaction equipment.

4.3 Suitability of On-site Soils

The subsurface SAND (SP-SM and SP) soils encountered appear to meet the recommended criteria for reuse as structural fill. Further classification testing (natural moisture content, gradation analysis, and Proctor testing) should be performed in the field during construction to evaluate the suitability of excavated soils for reuse as fill and backfill within building, pavement and utility areas.

4.4 Below Grade Parameters for Breakwater Concrete Sheet Piles

Below grade parameters to aid in the design of the proposed breakwater sheet piles are provided in Table III. Consideration should be given to the hydrostatic pressures when analyzing the proposed breakwater performance. These pressures should take into consideration the tidal fluctuations at the site. Also, appropriate safety factors should be maintained against kick-out or overturning failures. Per the Structural Engineer, overturning is to be resisted by the pier deck acting as a lateral restraint and tie back.

Table III - Below Grade Soil Parameters – Water borings

Stratum WATER CLAY SAND Yorktown

Elevation (ft. NAVD88) 0 to -16(1) -16 to

-30 to -51

-30 to -51 to

-60 to -66

-60 to -66 to

Termination Soil Classification

(USCS) N/A CH, CL SM, SP, SC SP-SM, SM, SC

Estimated Moist Unit Weight (pcf) N/A 105 120 122

Estimated Saturated Unit Weight (pcf) N/A 110 128 130

Estimated Buoyant Unit Weight (pcf) N/A 48 66 68

Friction Angle(2) () (degrees) N/A Φ’=20

Φ=9 32 34

Cohesion(2) (c) (psf) N/A c’=200 c=250 0 0

Active Soil Pressure(2)

Ka N/A Ka’=0.71 Ka=0.48 0.31 0.28

At-Rest Soil Pressure(2), Ko N/A Ko’=0.83

Ko=0.64 0.47 0.44

Passive Soil Pressure(2) Kp N/A Kp’=1.42

Kp=2.09 3.25 3.54

Soil Modulus Parameter, k (pci) N/A N/A 60 60

Soil Strain Parameter (E50) N/A 0.02 N/A N/A

1) Includes 5 feet of scour.

2) Total and effective parameters are provided in the table. Effective is represented with a prime (‘) next to the parameter.

4.5 Below Grade Parameters for Bulkhead

Below grade parameters to aid in the design of the bulkhead are provided in Table IV.

Consideration should be given to hydrostatic pressures when analyzing the bulkhead’s performance.

Table IV - Below Grade Soil Parameters

Stratum

UNCONTROLLED

FILL

CLAY SAND Yorktown

Elevation (ft. NAVD88) to

-11

-11 to -33

-33 to -51

-51 to -92

Soil Classification

(USCS) SP CH, CL SM, SP, SC SM, SC

Estimated Moist Unit Weight (pcf) 115 105 120 122

Estimated Saturated Unit Weight (pcf) 120 110 128 130

Estimated Buoyant Unit Weight (pcf) 58 48 66 68

Friction Angle(1) () (degrees) 26 Φ’=20

Φ=9 32 34

Cohesion(1) (c) (psf) 0 c’=200 c=250 0 0

Active Soil Pressure(2)

Ka 0.39 Ka’=0.71 Ka=0.48 0.31 0.28

At-Rest Soil Pressure(2), Ko 0.56 Ko’=0.83

Ko=0.64 0.47 0.44

Passive Soil Pressure(2) Kp 2.56 Kp’=1.42

Kp=2.09 3.25 3.54

Soil Modulus Parameter, k (pci) 20 N/A 60 60

Soil Strain Parameter (E50) N/A 0.02 N/A N/A

1) Total and effective parameters are provided in the table. Effective is represented with a prime (‘) next to the parameter.

4.6 Axial Compression Capacity Recommendations-Breakwater Pier

The proposed Breakwater Pier is expected to be ±200 feet long by ±20 feet wide. A deep foundation system is recommended to support the pier. The basis for design encompasses the following:

• Breakwater (north side) foundation system to be comprised of 16-inch thick Pre-stressed Concrete sheet piles reinforced by 20-inch SPPC, 24-inch SPPC, or HP-14 Steel vertical and battered piles.

• The concrete sheet piles are to be jetted into place. The pile capacity calculations include a reduction factor for jetting installation.

• South side foundation system to be comprised of 20-inch SPPC, 24-inch SPPC, or HP-14 Steel piles in alternating vertical and battered positions.

• Existing mudline elevation at -11 ft NAVD 88.

• Maximum design freeboard elevation extends to -16 feet NAVD88 (future scour elevation).

• Top of pier elevation is referenced at +7 feet NAVD88.

• A safety factor of 2.5 was utilized in the deep foundation design calculations based on using high-strain dynamic methods for load verification. See Section 4.6.3 for proposed Test Pile Program.

Allowable compressive and tensile capacities for 16-inch Prestressed Concrete sheet piles, the 20- to 24-inch SPPC piles, and HP-14 Steel piles are provided in Figures 3 through 6.

Figure 3: Allowable Compressive Capacity 16-inch Pre-stressed Concrete Sheet Pile

Figure 4: Allowable Compressive Capacity 20-inch SPPC Pile

Figure 5: Allowable Compressive Capacity 24-inch SPPC Pile

Figure 6: Allowable Compressive Capacity HP-14 Steel Pile

4.6.1 Pile Drivability Considerations

If for some reason during construction, pile driving “capacity” is encountered before the piles reach their design tip elevations, the Geotechnical Engineer should be retained to review driving records and field reports to determine whether the pile can adequately support the design loads. If the pile driving hammer is not properly matched to the pile type, size and subsurface conditions, it may reach practical refusal before the pile reaches the design tip elevation, or the required capacity.

Hard driving conditions are expected to occur between -60 to -65 feet NAVD 88 in elevation. To reduce the risk of pile refusal prior to reaching the design embedment depth and overstressing the piles, the following recommendations are proposed:

• The pile contractor should be consulted prior to construction to verify that the chosen pile system can be driven to the recommended depth.

• For pile groups, drive interior piles first.

• Assure pile driving equipment and pile cushions are appropriate to this application (see Section 4.6.5).

• Ensure proper alignment of the driving head.

• Drive or jet piles in a continuous manner. As previously stated, the soils within the project’s area typically exhibit time-dependent strength characteristics; the dynamics of driving piles will cause excess pore pressures to develop, thereby decreasing driving resistance during initial pile installation.

4.6.2 Negative Side Friction Discussion

The conditions that result in settlement that induces negative skin friction are not expected to be present at this project. As such, negative side friction is not included in our pile capacity calculations. Accordingly, ultimate capacity is simply the design capacity multiplied by the safety factor.

4.6.3 Test Piles

We recommend that a test pile program be implemented for the purpose of assisting in the development of final tip elevations, to confirm that the contractor’s equipment and installation methods are acceptable, and to provide an indication of various driving and/or installation conditions. The test pile locations should be established by the geotechnical engineer of record.

It is important to note the relationship between the required testing and our design assumptions.

We chose safety factors based upon the recommended pile testing program. We expect that the pile testing program will include primarily dynamic evaluation with a Pile Driving Analyzer (PDA).

The allowable compressive capacities provided in this report are based on a Safety Factor of 2.5.

Per Unified Facilities Criteria requirements (UFC 3-220-01), a Safety Factor of 2.5 is required if the pile acceptance relies solely on PDA testing, without static load tests. We recommend testing three (3) SPPC and three (3) concrete sheet indicator piles along the pier alignment, equidistant from each other.

The test piles should be driven using the drive system submitted by the contractor and approved by the geotechnical engineer. Test pile lengths should be at least ten feet longer than anticipated production pile lengths to ensure that the required capacity is developed, to allow for refinement of estimated capacities, and for dynamic and static testing reasons. The indicator piles installed during the Test Pile Program, which satisfy the geotechnical engineer’s requirements for proper installation, may also be used as permanent production piles.

The contractor should include in his equipment submittal a Wave Equation Analysis of pile drivability (using GRLWEAPTM software) modeling the behavior of the test piles during driving, or what is termed by GRL as a “Drivability Study.” The primary intent of the Wave Equation Drivability Study is to estimate the feasibility of the contractor’s proposed pile driving system with respect to installing the piles. Since the results of the Wave Equation Drivability Study are dependent on the chosen hammer, the pile type and length, and the subsurface conditions, it is likely that at least one Wave Equation Drivability Study per hammer will be required.

Pile driving equipment should not be mobilized for the test piles until the Wave Equation Drivability Study have been submitted and approved by the geotechnical engineer. If the contractor’s proposed pile driving system is rejected, subsequent submittals of alternative drive systems should also include appropriate Wave Equation Drivability Study that are subject to the approval of the geotechnical engineer. The Wave Equation Drivability Study are also used to estimate:

• Compressive and tensile stresses experienced by the modeled pile during driving.

• The total number of blows required to install each pile.

• Driving resistance (in terms of blows per foot) within the various soil strata.

• Driving time

The results of the WEAP analyses are highly dependent on the many input parameters related to the soil conditions, static pile capacity estimates, as well as specific characteristics associated with different makes and models of pile driving hammers.

4.6.4 Dynamic Testing

Dynamic testing was developed as a method of improving upon the reliability of the wave equation and other dynamic predictions by actually measuring the acceleration and strain of a pile during driving. This technique was developed in the mid-1960's and has been continually refined. The use of dynamic pile testing has permitted the possibility of checking the driving stresses in the pile and the hammer performance during pile driving. It is also possible to estimate the static capacity of the pile based upon the strain and acceleration measurements taken during pile driving.

The test pile installation should be monitored by the Geotechnical Engineer using the PDA, an electronic device that records driving stresses and pile/soil interactions, among other things. The PDA results will confirm that the pile driving system (hammer type/energy, cushion type/ thickness, etc.) can successfully install the piles without over stressing them in compression or tension. We recommended the owner retain the services of the Geotechnical Engineer to perform the dynamic testing, not the contractor, to avoid possible conflicts of interest.

No sooner than 7 days after installation, all of the test piles should be re-struck while being monitored with the PDA. This test establishes the “static capacity” of the pile. The initial hammer blow during re-strike activities is critical to the quality of dynamic data with respect to capacity interpretation. The contractor should make every effort to insure an initial high-energy blow of the hammer. After several blows during re-strike activities, pore pressures increase, soil setup diminishes, and ultimately pile capacities (as recorded by the PDA) decrease. Loss of estimated static capacity following repeated hammer blows is the reason the initial blows are critical.

The dynamic data recorded by the PDA during restrike testing should be further refined by using CAPWAP® analysis. CAPWAP® analysis, not the initial assessment of capacity determined by the PDA, should be the basis of static pile capacity estimates. Interpretation of CAPWAP® data, in the context of the soil subsurface conditions and previous static pile capacity estimates, should allow the Geotechnical Engineer to estimate ultimate pile capacities and recommend appropriate production pile lengths.

Our previous experience with the PDA indicates that a significant cost savings may be realized if the PDA is properly utilized to monitor the installation of test piles, confirm pile capacity in production installations, and monitor potentially damaging stresses during driving.

4.6.5 Establishing Pile Driving Criteria

Prior to driving production piles, the geotechnical engineer should establish the criteria for pile installation. The criteria will be based on the data collected during monitoring of the test pile installation and the subsequent restriking. The intent of establishing driving criteria is to facilitate installation of the production piles without damage and to provide a means of establishing when piles have achieved the design capacities. The driving criteria may include: hammer type, hammer energy, ram weight, pile cushion and thickness, hammer cushion type and thickness, required tip elevations and driving resistance necessary to achieve capacities, and possibly predrilling recommendations (if the test pile results warrant the need).

4.6.6 Allowable Driving Stresses

Concrete Piles

Guidelines from the American Association of State Highway Transportation Officials (AASHTO) indicate that maximum compressive stresses, imposed on driven precast concrete piles during installation, should be less than the following equation:

Maximum Compressive Stresses ( ) ( ) pec ff − '85.0

Where:

=cf ' concrete compressive strength =pef effective pre-stressing after losses from relaxation

The Maximum Tensile Stress recommended by AASHTO is pec ff + '3 .

Steel Piles

Based on the literature provided by ASCE (Design of Pile Foundations), allowable tension and compression stresses are given for both the lower and upper regions of the pile (conservatively defined as the embedded versus the exposed lengths of the pile, respectively). These stresses are on the order of 0.8 Fy to 0.9 Fy (Fy is the steel yield strength). Since the lower region of the pile is subject to damage during driving, the basic allowable stress should have a high factor of safety. The upper region of the pile may be subject to the effects of bending and buckling as well as axial loading. Since damage in the upper region of a pile is usually apparent during driving, a higher allowable stress is permitted. The upper region of the pile is designated as a beam-column, with due consideration to lateral support conditions.

4.6.7 Hammer Types and Energies

Concrete Piles

In comparing hammers of equal energy, the Prestressed Concrete Institute (PCI) states that hammers with heavier rams and lower impact velocities are less likely to cause damaging stresses in concrete piles. Hammers with proportionally higher ram weights and short stroke heights (low impact velocities) are usually air or steam driven, and not diesel fueled. It has been our experience that air/steam or hydraulic hammers are more appropriate for the installation of precast concrete piles than similarly sized (in terms of energy) diesel hammers. We recommend that the contractor use an air or steam driven hammer whose ram weight is roughly equal to 0.5 to 1.0 times the weight of the pile itself. The actual determination of an acceptable ram weight should be determined through the results of the Test Pile Program. If the contractor elects to use a diesel hammer, we recommend a critical, detailed review of the contractor’s Wave Equation Analysis prior to driving the test piles.

Steel Piles

Typically, hammers used in driving of steel piles have ram weights of about 0.75 to 1.5 the weight of the pile itself. The actual determination of an acceptable ram weight should be determined through the results of the Test Pile Program. If the contractor elects to use a diesel hammer, we recommend a critical, detailed review of the contractor’s Wave Equation Analysis prior to driving the test piles.

4.6.8 Driven Pile Installation Monitoring

The Geotechnical Engineer should observe the installation of the test piles and all production piles. The purpose of the Geotechnical Engineer’s observations is to determine if production installations are being performed in accordance with the previously derived Pile Driving Criteria.

Continuous driving and installation records should be maintained for all driven piles. Production piles should be driven utilizing the approved system established as a result of the Test Program.

The field duties of the Geotechnical Engineer (or a qualified engineer’s representative) should include the following:

• Being knowledgeable of the subsurface conditions at the site and the project-specific Pile Driving Criteria.

• Being aware of aspects of the installation including type of pile driving equipment and pile installation tolerances.

• Keeping an accurate record of pile installation and driving procedures.

• Documenting that the piles are installed to the proper depth indicative of the intended bearing stratum. Also, documenting that appropriate pile splicing techniques are used, if necessary.

• Recording the number of hammer blows for each foot of driving.

• Generally confirming that the pile driving equipment is operating as anticipated.

• Record the energy rating of the hammer.

• Informing the Geotechnical Engineer of any unusual subsurface conditions or driving conditions.

• Notifying the contractor and Structural Engineer when unanticipated difficulties or conditions are encountered.

• Confirming from visual appearance that the piles are not damaged during installation and observing the piles prior to installation for defective workmanship. The Geotechnical Engineer should review all driving records prior to pile cap construction.

4.6.9 Pile Group Settlement

Based on our experience with deep foundations in similar soil conditions, it is anticipated that the total butt settlements of the piles (including elastic shortening) will not exceed about 0.5 inches, which is the settlement necessary to mobilize the soil/pile capacity in combination with the pile group settlements due to the stress increase in the underlying soils.

4.7 Buried Utility Lines

Buried utility lines will be installed within the land-portion of the project site. It is expected that dewatering will be required for excavations that extend near or below the existing groundwater table. Dewatering considerations are provided in Section 5.3.

It is expected that utility lines will bear at 6 to 10 feet below grade. The soils recovered at these depths consist mostly of loose to medium dense SAND (SP, SP-SM). These soils appear to be suitable bedding material; thus, the excavation should extend 4 inches below the base of the proposed utilities to allow for a minimum of 4 inches of bedding material (VDOT No. 57 or No. 58 stone).

Should any unstable bearing conditions be encountered during construction, it is expected that these surfaces may warrant subsurface improvements to provide a stable bedding surface. These subsurface improvements are expected to consist of over-excavating the unstable soils approximately 12 to 24 inches, if necessary, line the exposed subsurface soils with a woven geotextile fabric (Mirafi HP270 or equivalent), and backfill with VDOT No. 57 or No. 58 stone.

Lateral earth pressure parameters are provided below in Table V. Dewatering and shoring are expected to be required during construction. Backfill material in utility trenches within the construction areas should consist of structural fill (as described in Section 4.3) and should be compacted to at least 98% of ASTM D1557. This fill should be placed in 4- to 6-inch loose lifts when hand compaction equipment is used.

Table V - Below Grade Soil Parameters

Stratum UNCONTROLLED FILL

Depth (ft) 0 to 10

Soil Classification (USCS) SP

Estimated Moist Unit Weight (pcf) 115

Estimated Saturated Unit Weight (pcf) 120

Estimated Buoyant Unit Weight (pcf) 58

Friction Angle () (degrees) 26

Cohesion (c) (psf) 0

Active Soil Pressure-Ka 0.39

At-Rest Soil Pressure-Ko 0.56

Passive Soil Pressure-Kp 2.56

5.0 CONSTRUCTION CONSIDERATIONS

5.1 Anticipated Excavation Characteristics

Based on the results of this exploration, varying soil conditions and compositions are expected to be encountered throughout the project limits. Open-cut excavations will extend through natural soils that are considered to be relatively “clean” (i.e. soil that is relatively free of deleterious debris that may hinder excavation or installation). Debris typically considered unsuitable consist of wood, glass, organics, plastics, coal, brick or any other material larger than 2 inches in diameter. Based on these characteristics it is anticipated that some of the shallow subsurface materials encountered within the project alignment may be reusable as backfill. Soils containing appreciable amounts of deleterious debris should be discarded; however, an effort should be made during excavation to segregate potentially suitable in-situ soils for reuse. Information pertaining to backfill criteria was provided previously in Section 4.2.

5.2 Excavation Stability

The shallow subsurface soil within the project limits is comprised of granular soils which the Contractor should anticipate having relatively little cohesion and a high potential for caving.

Additionally, water seepage at varying elevations should be expected within the side walls of the open cut areas, increasing the potential for caving. Based on these mentioned characteristics, it is recommended that all subsurface soils be considered Type C in accordance with Occupational Safety and Health Administration (OSHA) criteria.

Temporary Slopes

In Federal Register, Volume 54, No. 209 (October 1989), the United States Department of Labor, Occupational Safety and Health Administration (OSHA) amended its “Construction Standards for Excavations, 29 CFR, part 1926, Subpart P”. This document was issued to better ensure the safety of workmen entering trenches or excavations. It is mandated by this federal regulation that all excavations, whether they be utility trenches, basement excavations, or footing excavations, be constructed in accordance with the new (OSHA) guidelines. It is our understanding that these regulations are being strictly enforced and if they are not closely followed, the owner and the Contractor could be liable for substantial penalties.

Temporary slopes may not be a feasible option. The Contractor is solely responsible for designing and constructing stable, temporary excavations and should shore, slope, or bench the sides of the excavations as required to maintain stability of both the excavation sides and bottom. The Contractor’s responsible person, as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations as part of the Contractor’s safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety regulations.

Where temporary slopes are not feasible, shoring by means of sheeting and/or trench shields may be appropriate. Where the stability of adjoining structures, pavements, or other improvements is endangered by excavation operations, support systems such as shoring, bracing, or underpinning may be required to provide structural stability. Shoring, bracing, or underpinning required for this project (if required) should be designed by a professional engineer.

Shoring

Shoring design and installation should be the responsibility of the Contractor. Shoring systems required for this project should be designed by a professional engineer. Shoring systems should be designed to provide positive restraint of trench walls in an effort to protect against lateral deformation that may result in ground cracks, settlement, and/or other ground movements that may affect adjacent underground utilities and pavements as well as surface improvements. The Contractor should be made aware of this potential condition so that preventative measures can be implemented.

Depending on the shoring system used, the removal process may create voids along the walls of the excavations. If these voids are left in place and are significant, backfill and/or the retained soil may shift laterally resulting in settlement of overlying structures/pavements. As such, care should be taken to remove the shoring systems and backfill the trenches in a manner as to not create these voids.

In all cases, the Contractor should select an excavation and/or shoring scheme that will protect adjacent and overlying improvements, including below grade utilities.

We are providing this information solely as a service to our client. G E T Solutions, Inc. is not assuming responsibility for construction site safety or the Contractor’s activities; such responsibility is not being implied and should not be inferred.

5.3 Dewatering

It is expected that dewatering will be required for excavations that extend near or below the existing groundwater table. Temporary dewatering will impact construction and be dependent on construction methods and scheduling. For those reasons, we recommend the Contractor be solely responsible for the design, installation, maintenance, and performance of all temporary dewatering systems. The dewatering system should be designed to maintain a controlled environment suitable for the proposed construction and specified construction methods. Where temporary shoring is employed, the dewatering system should be compatible with the type of shoring to be used. We recommend the Contractor verify groundwater conditions and evaluate dewatering requirements prior to construction.

Lowering the groundwater table during dewatering activities will result in an increase in effective stresses and may induce settlements of the soils underlying adjacent structures/pavements.

Additionally, hydraulic compaction of predominately granular soils (e.g. SP, SP-SM, SM soils) should be anticipated as a result of lowering the groundwater table. We recommend that the dewatering be performed such that the groundwater level is lowered no more than approximately 5 feet below the proposed excavation depth. It may be advantageous to install settlement monuments in areas where dewatering by means of well pointing is required.

6.0 REPORT LIMITATIONS

The recommendations submitted are based on the available soil information obtained by G E T Solutions, Inc. and the information supplied by the client and their designated agents for the proposed project. If there are any revisions to the plans for this project or if deviations from the subsurface conditions noted in this report are encountered during construction, G E T Solutions, Inc. should be notified immediately to determine if changes in the foundation recommendations are required. If G E T Solutions, Inc. is not retained to perform these functions, G E T Solutions, Inc. can not be responsible for the impact of those conditions on the geotechnical recommendations for the project.

The Geotechnical Engineer warrants that the findings, recommendations, specifications or professional advice contained herein have been made in accordance with generally accepted professional geotechnical engineering practices in the local area. No other warranties are implied or expressed.

After the plans and specifications are more complete, the Geotechnical Engineer should be provided the opportunity to review the final design plans and specifications to make sure our engineering recommendations have been properly incorporated into the design documents, in order that the earthwork and foundation recommendations may be properly interpreted and implemented. At that time, it may be necessary to submit supplementary recommendations.

This report has been prepared for the exclusive use of the client and their designated agents for the specific application to the proposed V-47 Breakwater Pier project in Norfolk, Virginia.

APPENDICES

APPENDIX I BORING LOCATION PLAN

APPENDIX II CLASSIFICATION SYSTEM FOR SOIL EXPLORATION

APPENDIX III SUMMARY OF LABORATORY CLASSIFICATION RESULTS

APPENDIX IV BORING LOG

APPENDIX V TRIAXIAL TEST RESULTS

APPENDIX VI USGS 1978 GEOLOGY OF THE NORFOLK NORTH QUADRANGLE

APPENDIX VII SUPPORTING CALCULATIONS

APPENDIX VIII HISTORIC GEOTECHNICAL INFORMATION

APPENDIX I

BORING LOCATION PLAN

PROJECT: V-47 Breakwater Pier

PROJECT LOCATION: Norfolk, Virginia

PROJECT NO: VB20-265G

CLIENT: Moffatt & Nichol hschilling Text Box Boring Location Plan hschilling Line hschilling Stamp hschilling Stamp north arrow

V-47 Breakwater Pier Legend

Breakwater Pier Boring 20B-01

Previous Study Cores & Borings

Previous Study Water Borings

300 ft

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© 2020 Google

APPENDIX II

CLASSI…