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ENG FORM 4025-R, JUL 2015 REPLACES EDITION OF MAR 2012, WHICH IS OBSOLETEPage 1 of 1

Digitally signed by zachm@duwamishservices.com Date: 2020.11.11 16:30:11 -08:00

Robert Miner Dynamic Testing, Inc.

Dynamic Measurements and Analyses for Deep Foundations

November 11, 2020 Mr. Zachary Martin Duwamish Services LLC c/o Pacific Pile and Marine, LLC.

700 S Riverside Dr.

Seattle, WA 98108

Re: Dynamic Pile Measurements and Analyses Pile Dike 6.37: September 22 - October 5, 2020 Pile Dike 4.01: October 6 - 9, 2020 PP24"x0.50", APE D50-52 Diesel Impact Hammer Sand Island Test Pile Program Mouth of the Columbia River near Chinook, WA RMDT Job No. 20F36

Mr. Martin, This transmittal provides results obtained from dynamic pile measurements and analyses completed for the piles referenced above. The subject measurements and analyses were completed by Robert Miner Dynamic Testing, Inc. (RMDT) at the request of Duwamish Services, LLC and Pacific Pile and Marine, LLC.

TEST DETAILS

Piles:

The monitored piles were 24" OD steel pipe pies with a wall thickness of 0.50-inches. Four different pile tip configurations were advanced. These tip configurations were open-ended without tip protection advanced by only a vibratory hammer, open-ended with driving shoe (Ring), close-ended rock-breaking shoe (Rock), and close-ended conical tip (Cone). The latter three tip configurations were impact driven and are the subject of this report; we did not complete dynamic monitoring during vibratory pile driving. Tables 1a and 1b summarize certain pile details. RMDT observed manufacturer stencils indicating conformance to the ASTM A252 Gr 3 standard with a minimum material yield strength of 45 or 50 ksi.

General Site Conditions:

Project site conditions consisted of a single line of timber piling extending above high water level and armored by rock Rip-rap with thickness of 16 to 24 ft at the crest. Typically the crest of the rock rip-rap was 15 to 25 ft below the surface of the Columbia River. Strong tidal current fluctuations and potential for heavy wind waves or ground swell are likely at both site locations.

Figures 1, 2 and 3 provide general aspects of the setting.

Subsurface information contained in project documents suggest that the project site consists of 0 to 28 ft of rock rip-rap underlain by predominantly granular material which we assume extends below the required minimum tip elevation at both dike locations. Project documents do not provide specific information on the granular material.

Measurement and Analysis Method:

We collected dynamic measurements using two strain gages and two accelerometers attached to the pile 4 to 15 ft below the pile top. Signals from these sensors were collected and processed using a Pile Driving Analyzer ® (PDA) manufactured by Pile Dynamics, Inc. Figure 4 depicts typical dynamic measurements in progress. Following the testing we used the CAPWAP® program to compute the soil resistance acting on the pile. A description of the PDA and CAPWAP methods appears in Appendix A.

Mailing Address: P.O. Box 340, Manchester, WA, 98353, USA Phone: 360-871-5480 Location: 2288 Colchester Dr. E., Ste A, Manchester, WA, 98353 Fax: 360-871-5483

Duwamish Services c/o Pacific Pile and Marine, Sand Island Test Piles Nov 11, 2020 Page 2 RMDT Job No. 20F36

Hammer:

An APE D50-42 open-end diesel hammer drove all piles during dynamic monitoring. The APE D50-42 hammer has a ram weighing 11 kips, and a maximum energy rating of 124 kip-ft. We understand that the hammer was operated on Fuel Setting 2 during all impact driving.

Test Sequence:

Certain pile and test details relevant to the test sequence appear in Table 1a for Pile Dike 6.37 and in Table 1b for Pile Dike 4.01. Piles driven near the crest of the rock berm are labeled with a “C” in the pile name. An “F” in the pile name indicates a plan location offset from the crest, with such offset presumed to position the pile at or near the toe of the berm.

It is our opinion that all piles except Piles 6-4C Cone and 4-2C Ring were driven through the bottom of the rock rip-rap and into the underlying granular material while dynamic monitoring was occurring. For additional pile installation details please refer to project pile driving logs prepared by a representative of Duwamish Services, LLC and included in Appendix E.

RESULTS

Case Method Results Tables 2a and 2b summarize selected field Case Method results and other observed details for the End of Monitoring with the PDA (EOM) during impact driving. These results include measured transfer energy, EMX, the calculated ram stroke height, STK, and the average peak axial compressive driving stress at our sensor location, CSX. Appendix B contains graphic and numeric summaries of the Case Method Results as a function of pile penetration for impact driving.

The Case Method CSX values pertain to the location of the sensors near the pile top and are based on averaging measurements from the strain sensors on opposite sides of the pile. Near the end of impact driving on all piles the average CSX values were between 21 and 27 ksi at Pile Dike 6.36 and between 18 and 29 ksi at Pile Dike 4.01. CSX values averaged over 1 ft intervals at shallower depths were typically within 3 ksi of the tabulated CSX values for EOM.

The CSI stress values shown in Appendix B are obtained from the single sensor with the largest stress. The primary cause of any difference between CSX and CSI is usually considered to be uneven loading at the pile top. The average CSI values were typically within 2 to 6 ksi of the corresponding CSX values.

Two piles, Piles 6-4C Ring and 4-2C Ring, sustained significant deformation of the pile tip, with such deformation being observed after pile extraction. Pile 6-4C Ring sustained deformation which extended from the pile tip upward for approximately the 5 ft. Figures 5 and 6 are photos of Pile 6-4C Ring after pile extraction, pictured next to a pile with a “Rock Tip”. We consider it likely that this deformation was primarily caused by lateral forces which caused the pile to take on a non-circular plan view as it advanced through the rip-rap. Review of our Case Method results suggests that this deformation may have begun when the pile tip was approximately 21 to 22 ft below mudline. At a depth of 21 ft Case Method values for EMX, CSX, STK rose rapidly, and there was a temporary increase in Case Method estimates of driving resistance. This pile was driven to a depth of 25 ft below the crest of the rock with PDA monitoring and then 11 ft further prior to extraction.

Deformation to the tip of Pile 4-2C Ring was very similar to that of Pile 6-4C Ring. Pile 4-2C was advanced only 1.5 ft before impact driving terminated due to rapid pile deviation from vertical.

Case method EMX, CSX, STK values as well as estimate of ultimate resistance remained steady during the brief impact drive. Deformation of Pile 4-2C Ring may have started during vibratory installation, or during impact driving.

Page 3 RMDT Job No. 20F36

Deformation of the tip of Piles 6-4C Ring and 4-2C Ring was primarily lateral crimping to a non-circular shape such that the axial cross-sectional area, or acoustic impedance of the piles was little changed. We did not observe within our dynamic measurements sustained evidence of pile damage below our sensors; the time of the observed end reflection corresponded with the marked pile length. Thus, in this case the PDA measurements did not support identification of the pile deformation.

Given the incidence of pile damage on open end piles, it is our opinion that the use of open end piles presents a markedly higher risk of pile damage during driving through the rip rap.

Moreover, we did not observe that the open end piles provided a meaningful improvement in any aspect of initial advancement through the rip rap. The closed end (Cone and Rock Shoe) piles did not sustain significant damage observable upon extraction, and were also installed through the rip rap and the sand without hard driving. Thus, the apparently higher risk of damage to open-end piles may be an unnecessary higher risk.

Soil Resistance

The CAse Pile Wave Analysis Program (CAPWAP) computes soil resistance forces and their approximate distribution using the force and velocity data recorded in the field during dynamic monitoring. For each monitored pile, CAPWAP analyses were completed for one hammer blow measured near the end of PDA monitoring, EOM. Tables 3a and 3b summarize the results of the CAPWAP analyses and Appendix C contains the detailed CAPWAP results.

CAPWAP computed ultimate resistances ranged from 190 to 420 kips in Pile Dike 6.37 and from 170 to 490 kips in Pile Dike 4.01. Open-ended Ring piles tended to have the lowest end bearing values, and the three largest shaft friction values were for open end piles. For all pile tips the friction computed for elevations in the rip rap tended to be lower than the friction computed in the lower granular material. CAPWAP results suggested the lower granular material was highly variable across the project site. However, the lower material did not present hard driving conditions for either open or closed end piles.

The results presented herein apply to the conditions present when the testing occurred; this condition was continuous driving. Shaft friction values may have increased after driving stopped. Case Method values RX9 and RUC may be used to estimate driving resistance during monitoring at penetration depths other than EOM, and to evaluate the relative pattern of resistance as the piles advanced. Please see the cover sheet of Appendix B for information applicable to all of our measurements and analyses for this project.

Wave Equation Analysis

RMDT completed wave equation analyses guided by the available monitoring and CAPWAP analysis results. Such analyses for a D50 hammer reflect aspects of the field measurements, particularly transfer energy, as well as the CAPWAP analyses. We used the analysis format know as the GRLWEAP® Bearing Graph format. The bearing graph format computes the penetration resistance (blows per ft) predicted for a wide range of ultimate compressive resistance values at various stroke heights. For each assigned axial soil resistance the GRLWEAP Bearing Graph results include predicted peak axial compressive stresses and penetration resistance (blows per ft). We include results for the APE D50-42 hammer with adjustments to reflect project data. Because soil resistance in the rip rap and in the lower sand were very modest relative to the driving energy of the APE D50 operating with a modest stroke height we also analyzed an APE D30-52 impact hammer for reference or comparison purposes.

For both hammer models we completed wave equation analyses for two representative resistance conditions. These conditions modeled impact driving early in the pile advancement

Robert Miner Dynamic Testing, Inc.

g2encnab Sticky Note ring shoes may be damaged, unnecessary risk g2encnab Sticky Note no hard driving in lower materials

Page 4 RMDT Job No. 20F36 when the pile tip is in contact with the rock rip-rap, and also final driving with the pile tip in the underlying sand. Analyses for addressing these two different conditions are identified by a "Rock" or "Sand" in the output title block. In consideration of the field results wherein closed end piles remained substantially undamaged and two ring piles did suffer significant deformation, our present wave equation analyses consider only closed-end piles. Results of the Bearing Graph analysis for the two hammers and the two conditions are given on two pages in Appendix D; one page gives a summary of analysis details with a graphical summary of results and one page gives a tabulation of results.

APE D50-42

1. The GRLWEAP analyses modeling the pile tip bearing on rip-rap rock early in the driving process ("Rock") predicts axial compressive stress values below 40 ksi for stroke heights of 8.0 ft or less. At stroke heights greater than 8.0 ft, axial stress levels are predicted to exceed 40 ksi; the highest stress levels were computed for a location within 4 ft of the pile tip.

Analyses for a pile tip bearing in sand at a 40 ft tip depth ("Sand") predict axial compressive stress values below 33 ksi for the maximum analyzed stroke height of 8.7 ft. For all “Sand” analyses with the D50 hammer the maximum axial compressive stress is predicted to occur approximately 50 ft below the pile top.

2. In our opinion, a reasonable upper limit for driving resistance with this hammer, pile and soil combination is approximately 950 to 1000 kips at resistances the predicted penetration resistance exceeds 100 blows per ft. This opinion reflects analysis of hammer operation with reduced fuel settings, as modeled with reduced combustion chamber pressure.

APE D30-52

1. The GRLWEAP analyses modeling pile tip bearing on rip-rap rock early in the driving process ("Rock") predicts axial compressive stress values below 40 ksi for stroke heights of 9.0 ft or less. At stroke heights greater than 9.0 ft, axial stress levels are predicted to exceed 40 ksi; the highest stress levels were computed for a location within 4 ft of the pile tip. For “Sand” analyses with the D30 hammer the predicted axial compressive stress values were lower than 27 ksi for strokes up to 9.3 ft, and peak values were located approximately 55 ft below the pile top.

2. In our opinion, a reasonable upper limit for driving resistance with this hammer, pile and soil combination is approximately 700 to 750 kips at which resistance levels the predicted penetration resistance exceeds 100 blows per ft.

The wave equation analyses presented and discussed herein are for a 80 ft long pile of 24" OD and 0.5" wall thickness; changes in length or cross-sectional will effect computed driving stresses. The stresses computed in GRLWEAP analyses are axial stresses and thus do not include bending stresses or local contact stresses such as those that may result from non-uniform impact loading, bending, or non-uniform resistance forces at the pile toe, Such local stresses would be in addition to the GRLWEAP computed axial stresses. Thus, local stress concentrations, such as those which may result from driving in the rip-rap wherein contact with rock causes non-axial resistance or unbalanced end resistance, may cause pile deformation near the pile tip even if averaged axial stress is modest. To reduce the risk of such deformation we suggest that the ram stroke height be limited. At this time we suggest a stroke limit of approximately 7 and 8 ft for the D50 and D30 hammers, respectively, when driving in the rock, or if obstructions are encountered.

Robert Miner Dynamic Testing, Inc.

g2encnab Sticky Note Because damage to the piles was not "detectable" via PDA, wouldn't the WEA still be accurate for both open and closed end driving?

Page 6 RMDT Job No. 20F36

Table 1a. Pile Details and Summary of Test Sequence For Pile Dike 6.37

Pile ID 6-1C Ring

6-1C Rock

6-2C Cone

6-2C Rock

6-2F Ring

6-2F Cone

6-3C Rock

6-3C Ring

6-4C Ring

6-4C Cone

Pile Shoe Ring Rock Cone Rock Ring Cone Rock Ring Ring Cone

Impact Hammer D50 D50 D50 D50 D50 D50 D50 D50 D50 D50

Date of Initial Dynamic Monitoring Oct 5 Oct 5 Sept 30 Oct 5

Sept

Sept

Sept

Sept

Sept

Sept

Pile Length, ft 65 65 60 60 80 80 60 80 60 60

Approx. Mudline Elevation, ft -13.3 -12.0 -14.3 -15.7 -21.1 -23.1 -11.3 -14.7 -11.7 -12.5

Approx. Rock Thickness From Plans, ft 16 16 19 19 8 8 21 21 23 23

Initial Soil Penetration with Vibratory Hammer (ft)

12 10 11 8 24 15 15 19 13 13

EOM Tip Elev, ft -45.3 -33.0 -50.3 -40.7 -62.0 -58.1 -37.3 -54.7 -36.7 -30.5

EOM Soil Penetration, ft 32 21 36 25 41 36 26 40 25 18

EOM Blow Count, blows/set 5/1ft 6/1ft 9/1ft 9/1ft 9/1ft 9/1ft 8/1ft 10/1ft 10/1ft 8/1ft

Final Tip Elev, ft -49.3 - - -51.7 -64.0 -59.1 -47.3 - -47.7 -

Final Soil Penetration, ft 36 - - 36 43 37 36 - 36 -

Final Blow Count, blows/set 5/1ft - - 12/1ft 12/1ft 7/1ft 12/1ft - 8/1ft -

Visual Pile Damage No No No No No No No No Yes No

End of Monitoring (EOM) indicates the end of impact driving with PDA sensors attached. Final indicates the end of impact driving if impact driving continued after PDA sensors were removed.

Tabulated Blow counts (penetration resistance values), tip elevations and soil penetration values provided by Contractor.

Page 7 RMDT Job No. 20F36

Table 1b. Pile Details and Summary of Test Sequence For Pile Dike 4.01

Pile ID 4-1C Cone

4-1F Cone

4-1F Ring

4-2C Cone

4-2C Ring

4-2F Cone

4-3C Cone

4-3C Ring

4-4C Cone

4-4C Rock

Pile Shoe Cone Cone Ring Cone Ring Cone Cone Ring Cone Rock

Impact Hammer D50 D50 D50 D50 D50 D50 D50 D50 D50 D50

Date of Initial Dynamic Monitoring Oct 7 Oct 6 Oct 6 Oct 9 Oct 9 Oct 8 Oct 8 Oct 8 Oct 8 Oct 9

Pile Length, ft 71 80 80 70 65 70 70 65 70 65

Approx. Mudline Elevation, ft -12.9 -27.7 -22.7 -10.5 -10.4 -24.6 -12.0 -14.4 -14.7 -13.4

Approx. Rock Thickness From Plans, ft 11 2 2 19 19 5 20 20 24 24

Initial Soil Penetration with Vibratory Hammer (ft)

9 24 21 16 20 21 21 17 14 13

EOM Tip Elev, ft -43.9 -60.2 -60.7 -34.5 -31.9 -58.6 -54.0 -45.4 -50.7 -46.9

EOM Soil Penetration, ft 31.0 32.5 38.0 24 21.5 34 42 31 36 33.5

EOM Blow Count, blows/set 6/1ft 7/6in 15/1ft 11/1ft 8/6in 10/1ft 7/1ft 6/1ft 7/1ft 4/6in

Final Tip Elev, ft -51.9 -68.7 - - - -63.6 - -52.4 -55.7 -55.4

Final Soil Penetration, ft 39 41 - - - 39 - 38 41 42

Final Blow Count, blows/set 16/1ft 16/1ft - - - 15/1ft - 8/1ft 20/1ft 13/1ft

Visual Pile Damage No No No No Yes No No No No No

End of Measurements (EOM) designates the end of impact driving with PDA sensors attached. Final designates end of impact driving if impact driving continued after PDA sensors were removed.

Tabulated Blow counts (penetration resistance values), tip elevations and soil penetration values provided by Contractor.

Page 8 RMDT Job No. 20F36

Table 2a. Summary of Case Method Results for Pile Dike 6.37

Pile Test Approx.

Pile

Depth in Soil

(ft)

Approx.

Rock

Thickness From Plans

(ft)

Reported Penetration Resistance

(blows/set)

Average Transfer Energy, EMX

(kip-ft)

Computed Ram

Stroke, STK

(ft)

Comp.

Stress, CSX

(ksi)

6-1C Ring EOM 32 16 5/1ft 51 5.9 23

6-1C Rock EOM 21 16 6/1ft 38 5.1 21

6-2C Cone EOM 36 19 9/1ft 53 6.8 25

6-2C Rock EOM 25 19 9/1ft 58 7.2 27

6-2F Ring EOM 41 8 9/1ft 45 7.1 27

6-2F Cone EOM 36 8 9/1ft 51 6.8 26

6-3C Rock EOM 26 21 8/1ft 50 6.5 26

6-3C Ring EOM 40 21 10/ft 49 6.3 26

6-4C Ring EOM 25 23 10/1ft 52 6.2 27

6-4C Cone EOM 18 23 8/1ft 48 6.5 25

Table 2b. Summary of Case Method Results for Pile Dike 4.01

Pile Test Approx.

Pile

Depth in Soil

(ft)

Approx.

Rock

Thickness From Plans

(ft)

Reported Penetration Resistance

(blows/set)

Average Transfer Energy, EMX

(kip-ft)

Computed Ram

Stroke, STK

(ft)

Comp.

Stress, CSX

(ksi)

4-1C Cone EOM 31 11 6/1ft 32 5.2 18

4-1F Cone EOM 32.5 2 7/6in 52 6.9 26

4-1F Ring EOM 38 2 15/1ft 55 7.6 29

4-2C Cone EOM 24 19 11/1ft 48 6.5 24

4-2C Ring EOM 21.5 19 8/6in 58 7.4 29

4-2F Cone EOM 34 5 10/1ft 53 6.5 26

4-3C Cone EOM 42 20 7/1ft 47 6.4 23

4-3C Ring EOM 31 20 6/1ft 44 5.6 23

4-4C Cone EOM 36 24 7/1ft 40 5.7 21

4-4C Rock EOM 33.5 24 4/6in 50 5.5 23

Page 9 RMDT Job No. 20F36

Table 3. Summary of CAPWAP Results For Pile Dike 6.37

Pile Test Approx . Pile

Depth in Soil

(ft)

Approx.

Rock

Thickness From Plans

(ft)

Reported Penetration Resistance (blows/set)

Computed Soil Resistance, kips

Total Shaft Toe

6-1C Ring EOM 32 16 5/1ft 190 90 100

6-1C Rock EOM 21 16 6/1ft 210 100 110

6-2C Cone EOM 36 19 9/1ft 400 110 290

6-2C Rock EOM 25 19 9/1ft 420 90 320

6-2F Ring EOM 41 8 9/1ft 310 190 120

6-2F Cone EOM 36 8 9/1ft 340 70 270

6-3C Rock EOM 26 21 8/1ft 320 90 230

6-3C Ring EOM 40 21 10/ft 360 170 190

6-4C Ring EOM 25 23 10/1ft 260 90 170

6-4C Cone EOM 18 23 8/1ft 240 60 180

Table 3b. Summary of CAPWAP Results For Pile Dike 4.01

Pile Test Approx.

Pile

Depth in Soil

(ft)

Approx.

Rock

Thickness From Plans

(ft)

Reported Penetration Resistance (blows/set)

Computed Soil Resistance, kips

Total Shaft Toe

4-1C Cone EOM 31 11 6/1ft 170 65 105

4-1F Cone EOM 32.5 2 7/6in 470 120 350

4-1F Ring EOM 38 2 15/1ft 490 220 270

4-2C Cone EOM 24 19 11/1ft 340 130 210

4-2C Ring EOM 21.5 19 8/6in 390 70 320

4-2F Cone EOM 34 5 10/1ft 380 90 290

4-3C Cone EOM 42 20 7/1ft 270 75 195

4-3C Ring EOM 31 20 6/1ft 220 100 120

4-4C Cone EOM 36 24 7/1ft 220 80 140

4-4C Rock EOM 33.5 24 4/6in 240 90 150

Page 10 RMDT Job No. 20F36

Figure 1.Existing Pile Dike 6.37 Looking South

Figure 2. Existing Pile Dike 6.37 Looking North with Tidal Current Present

Page 11 RMDT Job No. 20F36

Figure 3: Pile Driving Derrick On Location at Pile Dike 6.37

Figure 4: High Strain Dynamic Measurements of Impact Driving

Page 12 RMDT Job No. 20F36

Figure 5: Pile Dike 6.37 Pile 6-42C Ring Tip Deformation

Figure 6: Pile Dike 6.37 Pile 6-42C Ring Tip Deformation, Close-up

A-1© 1999, Goble Rausche Likins and Associates, Inc.

APPENDIX A

AN INTRODUCTION INTO DYNAMIC PILE TESTING METHODS

The following has been written by Goble Rausche Likins and Associates, Inc. and may only be copied with its written permission.

BACKGROUND

Modern procedures of design and construction control require verification of bearing capacity and integrity of deep foundations during preconstruction test programs and also production installation. Dynamic pile testing methods meet this need economically and reliably, and therefore, form an important part of a quality assurance program when deep foundations are executed. Several dynamic pile testing methods exist; they have different benefits and limitations and different requirements for proper execution.

The Case Method of dynamic pile testing, named after the Case Institute of Technology where it was developed between 1964 and 1975, requires that a substantial ram mass (such as that of a pile driving hammer) impacts the pile top such that the pile undergoes at least a small permanent set. The method is therefore also referred to as a “High Strain Method”. The Case Method requires dynamic measurements on the pile or shaft under the ram impact and then an evaluation of various quantities based on closed form solutions of the wave equation, a partial differential equation describing the motion of a rod under the effect of an impact. Conveniently, measurements and analyses are done by a single piece of equipment: the Pile Driving Analyzer® (PDA).

However, for bearing capacity evaluations an important additional method is CAPWAP® which performs a much more rigorous analysis of the dynamic records than the simpler Case Method.

A related analysis method is the “Wave Equation Analysis” which calculates a relationship between bearing capacity and pile stress and field blow count.

The GRLWEAP™ program performs this analysis and provides a complete set of helpful information and input data.

The following description deals primarily with the Case Method or “High Strain Test” Method of pile testing, however, for the sake of completeness, the “Low Strain Test” performed with the Pile Integrity Test™ (PIT), mainly for pile integrity evaluation, will also be described.

RESULTS FROM DYNAMIC TESTING

There are two main objectives of high strain dynamic pile testing:

• Dynamic Pile Monitoring and

• Dynamic Load Testing.

Dynamic pile monitoring is conducted during the installation of impact driven piles to achieve a safe and economical pile installation. Dynamic load testing, on the other hand, has as its primary goal the assessment of pile bearing capacity. It is applicable to both cast insitu piles or drilled shafts and impact driven piles during restrike.

Dynamic Pile Monitoring

During pile installation, the sensors attached to the pile measure pile top force and velocity. A PDA conditions and processes these signals and calculates or evaluates:

• Bearing capacity at the time of testing, including an assessment of shaft resistance development and driving resistance. This information supports formulation of a driving criterion.

• Dynamic pile stresses, axial and averaged over the pile cross section, both tensile and compressive, during pile driving to limit the potential of damage either near the pile top or along its length. Bending stresses can be evaluated at the point of sensor attachment.

• Pile integrity assessment by the PDA is based on the recognition of certain wave reflections from along the pile. If detected early enough, a pile may be saved from complete destruction. On the other hand, once damage is recognized measures can be taken to prevent reoccurrence.

• Hammer performance parameters including the energy transferred to the pile, the hammer speed in blows per minute and the stroke of open ended diesel hammers.

A-2

Dynamic Pile Load Testing

Bearing capacity testing of either driven piles or drilled shafts applies the same basic measurement approach of dynamic pile monitoring. However, the test is done independent of the pile installation process and therefore a pile driving hammer or other dynamic loading device may not be available. If a special ram has to be mobilized then its weight should be between 0.8 and 2% of the test load (e.g. between 4 and 10 tons for a 500 ton test load) to assure sufficient soil resistance activation.

For a successful test, it most important that the test is conducted after a sufficient waiting time following pile installation for soil properties approaching their long term condition or concrete to properly set. During testing, PDA results of pile/shaft stresses and transferred energy are used to maintain safe stresses and assure sufficient resistance activation. For safe and sufficient testing of drilled shafts, ram energies are often increased from blow to blow until the test capacity has been activated. On the other hand, restrike tests on driven piles may require a warm hammer so that the very first blow produces a complete resistance activation. Data must be evaluated by CAPWAP for bearing capacity.

After the dynamic load test has been conducted with sufficient energy and safe stresses, the CAPWAP analysis provides the following results:

• Bearing capacity i.e. the mobilized capacity present at the time of testing

• Resistance distribution including shaft resistance and end bearing components

• Stresses in pile or shaft calculated for both the static load application and the dynamic test. These stresses are averages over the cross section and do not include bending effects or nonuniform contact stresses, e.g. when the pile toe is on uneven rock.

• Shaft impedance vs depth; this is an estimate of the shaft shape if it differs substantially from the planned profile

• Dynamic soil parameters for shaft and toe, i.e.

damping factors and quakes (related to the dynamic stiffness of the resistance at the pile/soil interface.)

MEASUREMENTS

PDA

The basis for the results calculated by the PDA are pile top strain and acceleration measurements which are converted to force and velocity records, respectively. The PDA conditions, calibrates and displays these signals and immediately computes average pile force and velocity thereby eliminating bending effects. Using closed form Case Method solutions, based on the one-dimensional linear wave equation, the PDA calculates the results described in the analytical solutions section below.

HPA

The ram velocity may be directly obtained using radar technology in the Hammer Performance Analyzer™. For this unit to be applicable, the ram must be visible. The impact velocity results can be automatically processed with a PC or recorded on a strip chart.

Saximeter™

For open end diesel hammers, the time between two impacts indicates the magnitude of the ram fall height or stroke. This information is not only measured and calculated by the PDA but also by the convenient, hand-held Saximeter.

PIT

The Pile Integrity Tester™ (PIT) can be used to evaluate defects in concrete piles or shafts which may have occurred during driving or casting. Also timber piles of limited length can be tested in that manner. This so-called "Low Strain Method" or “Pulse-Echo Method” of integrity testing requires only the measurement of acceleration at the pile top. The stress wave producing impact is then generated by a small hand-held hammer and the records interpreted in the time domain. PIT also supports the so-called “Transient Response Method” which requires the additional measurement of the hammer force and an analysis in the frequency domain. This method may also be used to evaluate the unknown length of deep foundations under existing structures.

A-4 therefore requires no damping parameter. In any event, the proper Case Method and its associated damping parameter is most conveniently found after a CAPWAP analysis has been performed.

The static resistance calculated by Case Method or CAPWAP is the mobilized resistance at the time of testing. Consideration therefore has to be given to soil setup or relaxation effects and whether or not a sufficient set has been achieved under the test loading that would correspond to a full activation of the ultimate soil resistance.

The PDA also calculates an estimate of shaft resistance as the difference between force and velocity times impedance at the time immediately prior to the return of the stress wave from the pile toe.

This shaft resistance is not reduced by damping effects and is therefore called the total shaft resistance SFT. A correction for damping effects produces the static shaft resistance estimate, SFR.

The Case Method solution is simple enough to be evaluated "in real time," i.e. between hammer blows, using the PDA. It is therefore possible to calculate all relevant results for all hammer blows and plot these results as a function of depth or blow number. This is done in the PDAPLOT program.

CAPWAP

The CAse Pile Wave Analysis Program combines the wave equation pile and soil model with the Case Method measurements. Thus, the solution includes not only the total and static bearing capacity values but also the shaft resistance, end bearing, damping factors and soil stiffnesses. The method iteratively calculates a number of unknowns by signal matching.

While it is necessary to make hammer performance assumptions for a GRLWEAP analysis, the CAPWAP program works with the pile top measurements.

Furthermore, while GRLWEAP and Case Method require certain assumptions regarding the soil behavior, CAPWAP calculates these soil parameters.

STRESSES

During pile monitoring, it is important that compressive stress maxima at pile top and toe and tensile stress maxima somewhere along the pile be calculated for each hammer blow.

At the pile top (location of sensors) both the maximum compression stress, CSX, and the maximum stress from individual strain transducers, CSI, are directly obtained from the measurements.

Note that CSI is greater than or equal to CSX and the difference between CSI and CSX is a measure of bending in the plane of the strain transducers.

Note also that all stresses calculated for locations below the sensors are averaged over the pile cross section and therefore do not include components from either bending or eccentric soil resistance effects.

The PDA calculates the compressive stress at the pile bottom, CSB, assuming (a) a uniform pile and

(b) that the pile toe force is the maximum value of the total resistance R(t) minus the total shaft resistance, SFT. Again, for this stress estimation uniform resistance force are assumed (e.g. not a sloping rock.)

For concrete piles, the maximum tension stress, TSX, is also of great importance. It occurs at some point below the pile top. The maximum tension stress can be computed from the pile top measurements by finding the maximum tension

Uwave (either traveling upward, W , or downward, dW ) and reducing it by the minimum compressive wave traveling in opposite direction.

uW = ½[F(t) - Zv(t)] (4) dW = ½[F(t) + Zv(t)] (5)

CAPWAP also calculates tensile and compressive stresses along the pile and, in general, more accurately than the PDA. In fact, for non-uniform piles or piles with joints, cracks or other discontinuities, the closed form solutions from the PDA may be in error.

PILE INTEGRITY

High Strain Tests (PDA)

Stress waves in a pile are reflected wherever the pile impedance, Z = EA/c = DcA = A o(E D), changes.

Therefore, the pile impedance is a measure of the quality of the pile material (E, D, c) and the size of its cross section (A). The reflected waves arrive at the pile top at a time which is greater the farther away from the pile top the reflection occurs. The

A-5 magnitude of the change of the upward traveling wave (calculated from the measured force and velocity, Eq. 4) indicates the extent of the cross isectional change. Thus, with $ (BTA) being a relative integrity factor which is unity for no impedance change and zero for the pile end, the following is calculated by the PDA.

i i i$ = (1 - " )/(1 + " ) (6) with i UR UD Di UR" = ½(W - W )/(W - W ) (7) where

UR is the upward traveling wave at the onset ofW the reflected wave. It is caused by resistance.

UD is the upwards traveling wave due to theW damage reflection.

DiW is the maximum downward traveling wave due to impact.

It can be shown that this formulation is quite accurate as long as individual reflections from different pile impedance changes have no overlapping effects on the stress wave reflections.

Without rigorous derivation, it has been proposed to consider as slight damage when $ is above 0.8 and a serious damage when $ is less than 0.6.

Low Strain Tests (PIT)

The pile top is struck with a held hand hammer and the resulting pile top velocity is measured, displayed and interpreted for signs of wave reflections. In general, a comparison of the reflected acceleration leads to a relative measure of extent of damage, again the location of the problem is indicated by the arrival time of the reflection. PIT records can also be interpreted by the $-Method. However, low strain tests do not activate much resistance which simplifies

UREq. 7 since W is then equal to zero.

For drilled shafts and PIT records that clearly show a toe reflection, an approximate shaft profile can be calculated from low strain records using the PITSTOP program’s PROFILE routine.

HAMMER PERFORMANCE

The PDA calculates the energy transferred to the pile top from:

oE(t) = I F(t)v(t) dt (8a)t

The maximum of the E(t) curve is the most important information for an overall evaluation of the performance of a hammer and driving system. This

EMX value allows for a classification of the hammer's performance when presented as the rated transfer efficiency, also called energy transfer ratio

(ETR) or global efficiency

T Re = EMX/E (8b) where

RE is the manufacturer’s rated energy value.

Both Saximeter and PDA calculate the stroke (STK) of an open end diesel hammer using

B LSTK = (g/8) T - h (9)2 where g is the earth’s gravitational acceleration, BT is the time between two hammer blows, Lh is a stroke loss value due to gas compression and time losses during impact (usually 0.3 ft or

0.1 m).

DETERMINATION OF WAVE SPEED

An important facet of dynamic pile testing is an assessment of pile material properties. Since in general force is determined from strain by multiplication with elastic modulus, E, and cross sectional area, A, the dynamic elastic modulus has to be determined for pile materials other than steel.

In general, the records measured by the PDA clearly indicate a pile toe reflection as long as pile penetration per blow is greater than 1 mm or .04 inches. The time between the onset of the force and velocity records at impact and the onset of the reflection from the toe (usually apparent by a local maximum of the wave up curve) is the so-called wave travel time, T. Dividing 2L (L is here the length of the pile below sensors) by T leads to the stress wave speed in the pile:

c = 2L/T (10)

A-6

The elastic modulus of the pile material is related to the wave speed according to the linear elastic wave equation theory by

E = c D (11)2

Since the mass density of the pile material, D, is usually well known (an exception is timber for which samples should be weighed), the elastic modulus is easily found from the wave speed. Note, however, that this is a dynamic modulus which is generally higher than the static one and that the wave speed depends to some degree on the strain level of the stress wave. For example, experience shows that the wave speed from PIT is roughly 5% higher than the wave speed observed during a high strain test.

Other Notes:

• If the pile material is nonuniform then the wave speed c, according to Eq. 10, is an average wave speed and does not necessarily reflect the pile material properties of the location where the strain sensors are attached to the pile top. For example, pile driving often causes fine tension cracks some distance below the top of concrete piles. Then the average c is slower than that at the pile top. It is therefore recommended to determine E in the beginning of pile driving and not adjust it when the average c changes.

• If the pile has such a high resistance that there is no clear indication of a toe reflection then the wave speed of the pile material must be determined either by assumption or by taking a sample of the concrete and measuring its wave speed in a simple free column test. Another possibility is to use the proportionality relationship, discussed under “DATA QUALITY CHECKS” to find c as the ratio between the measured velocity and measured strain.

DATA QUALITY CHECKS

Quality data is the first and foremost requirement for accurate dynamic testing results. It is therefore important that the measurement engineer performing PDA or PIT tests has the experience necessary to recognize measurement problems and take appropriate corrective action should problems develop. Fortunately, dynamic pile testing allows for certain data quality checks because two independent measurements are taken that have to conform to certain relationships.

Proportionality

As long as there is only a wave traveling in one direction, as is the case during impact when only a downward traveling wave exists in the pile, force and velocity measured at the pile top are proportional

F = v Z = v (EA/c) (12a)

This relationship can also be expressed in terms of stress

F = v (E/c) (12b) or strain

, = v / c (12c)

This means that the early portion of strain times wave speed must be equal to the velocity unless the proportionality is affected by high friction near the pile top or by a pile cross sectional change not far below the sensors. Checking the proportionality is an excellent means of assuring meaningful measurements.

Measurements are always taken at opposite sides of the pile as a means of calculating the average force and velocity in the pile. The velocity on the two sides of the pile is very similar even when high bending exists. Thus, an independent check of the velocity measurements is easy and simple.

Strain measurements may differ greatly between the two sides of the pile when bending exists. It is even possible that tension is measured on one side while very high compression exists on the other side of the pile. In extreme cases, bending might be so high that it leads to a nonlinear stress distribution. The averaging of the two strain signals does then not lead to the average pile force and proportionality will not be achieved.

When testing drilled shafts, measurements of strain may also be affected by local concrete quality variations. It is then often necessary to use four strain transducers spaced at 90 degrees around the pile for an improved strain data quality. The use of four transducers is also recommended for large pile

A-7 diameters, particularly when it is difficult to mount the sensors at least two pile widths or diameters below the pile top.

LIMITATIONS, ADDITIONAL CONSIDERATIONS

Mobilization of capacity

Estimates of pile capacity from dynamic testing indicate the mobilized pile capacity at the time of testing. At very high blow counts (low set per blow), dynamic test methods tend to produce lower bound capacity estimates as not all resistance (particularly at and near the toe) is fully activated.

Time dependent soil resistance effects

Static pile capacity from dynamic method calculations provide an estimate of the axial pile capacity.

Increases and decreases in the pile capacity with time typically occur (soil setup/relaxation). Therefore, restrike testing usually yields a better indication of long term pile capacity than a test at the end of pile driving. Often a wait period of one or two days between end of driving and restrike is satisfactory for a realistic prediction of pile capacity but this waiting time depends, among other factors, on the permeability of the soil.

(A) Soil setup

Because excess positive pore pressures often develop during pile driving in fine grained soil (clays, silts or even fine sands), the capacity of a pile at the time of driving may often be less than the long term pile capacity. These pore pressures reduce the effective stress acting on the pile thereby reducing the soil resistance to pile penetration, and thus the pile capacity at the time of driving. As these pore pressures dissipate, the soil resistance acting on the pile increases as does the axial pile capacity. This phenomena is routinely called soil setup or soil freeze.

(B) Relaxation

Relaxation (capacity reduction with time) has been observed for piles driven into weathered shale, and may take several days to fully develop. Pile capacity estimates based upon initial driving or short term restrike tests can significantly overpredict long term pile capacity. Therefore, piles driven into shale should be tested after a minimum one week wait either statically or dynamically (with particular emphasis than on the first few blows). Relaxation has also been observed for displacement piles driven into dense saturated silts or fine sands due to a negative pore pressure effect at the pile toe.

Again, restrike tests should be used, with great emphasis on early blows.

Capacity results for open pile profiles

Larger diameter open ended pipe piles (or H-piles which do not bear on rock) may behave differently under dynamic and static loading conditions. Under dynamic loads the soil inside the pile or between its flanges may slip and produce internal friction while under static loads the plug may move with the pile, thereby creating end bearing over the full pile cross section. As a result both friction and end bearing components may be different under static and dynamic conditions.

CAPWAP Analysis Results

A portion of the soil resistance calculated on an individual soil segment in a CAPWAP analysis can usually be shifted up or down the shaft one soil segment without significantly altering the match quality. Therefore, use of the CAPWAP resistance distribution for uplift, downdrag, scour, or other geotechnical considerations should be made with an understanding of these analysis limitations.

Stresses

PDA and CAPWAP calculated stresses are average values over the cross section. Additional allowance has to be made for bending or non-uniform contact stresses. To prevent damage it is therefore important to maintain good hammer-pile alignment and to protect the pile toes using appropriate devices or an increased cross sectional area.

In the United States is has become generally acceptable to limit the dynamic installation stresses of driven piles to the following levels:

90% of yield strength for steel piles

85% of the concrete compressive strength - after subtraction of the effective prestress - for concrete piles in compression

A-8

100% of effective prestress plus ½ of the concrete’s tension strength for prestressed piles in tension

70% of the reinforcement strength for regularly reinforced concrete piles in tension

300% of the static design allowable stress for timber

Note that the dynamic stresses may either be directly measured at the pile top by the PDA or calculated by the PDA for other locations along the pile based on the pile top measurements.

Additional design considerations

Numerous factors have to be considered in pile foundation design. Some of these considerations include

• additional pile loading from downdrag or negative skin friction,

• lateral and uplift loading requirements

• effective stress changes (due to changes in water table, excavations, fills or other changes in overburden),

• long term settlements in general and settlement from underlying weaker layers and/or pile group effects, These factors have not been evaluated by GRL and have not been considered in the interpretation of the dynamic testing results. The foundation designer should determine if these or any other considerations are applicable to this project and the foundation design.

Wave equation analysis results

The results calculated by the wave equation analysis program depend on a variety of hammer, pile and soil input parameters. Although attempts have been made to base the analysis on the best available information, actual field conditions may vary and therefore stresses and blow counts may differ from the predictions reported. Capacity predictions derived from wave equation analyses should use restrike information. However, because of the uncertainties associated with restrike blow counts and restrike hammer energies, correlations of such results with static test capacities with have often displayed considerable scatter.

As for PDA and CAPWAP, the theory on which GRLWEAP is based is the one-dimensional wave equation. For that reason, stress predictions by the wave equation analysis can only be averages over the pile cross section. Thus, bending stresses or stress concentrations due to non-uniform impact or uneven soil or rock resistance are not considered in these results. Stress maxima calculated by the wave equation are usually subjected to the same limits as those measured directly or calculated from measurements by the PDA.

Appendix B

Summary of Field Case Method Results

The static soil resistance values computed with the Case Method and from CAPWAP are estimates of the mobilized, axial compressive soil resistance at the time of testing.

These soil resistance results are ultimate resistance values and they must be reduced by an appropriate factor of safety or resistance factor to obtain working or factored loads.

The detailed CAPWAP results include computed shaft resistance values versus depth for segments of approximately 6 to 7 ft length. Computed unit friction and unit bearing values in units of kips per square ft are included. The primary CAPWAP results are those expressed in force (kips); the unit values are secondary CAPWAP results and are based on the conversion assuming a nominal outside pile perimeter, and the steel end projection of an open or closed-ended pipe pile. These perimeter and end area values were used only to compute unit values; the assigned perimeter and end areas do not effect the primary CAPWAP results given in kip units.

During pile driving, excess positive pore pressures are often generated. These pore pressures reduce the effective stress acting on the pile thereby reducing the soil resistance to pile penetration, and the pile capacity at the time of driving. As such excess pore pressures dissipate the soil strength increases and the soil resistance increases. This phenomena is often called soil setup or “soil freeze”. Alternately, relaxation of end bearing may occur for piles driven into rock or into dense granular soils which dilate during shear. Dynamic testing during restrike with adequate set per blow usually yields a better indication of long term soil resistance than a test at the end of pile driving.

Numerous factors are usually considered in pile foundation design. Some of these considerations include cyclic loading performance, lateral and uplift loading requirements, effective stress changes (due to changes in water table, excavations, fills or other changes in overburden pressure), settlement from underlying weaker layers, the effects of scour or liquefaction on pile capacity, as well as pile group effects, strong ground motion, and time dependant or temperature dependent changes to the strength of the pile or soil . These factors have not been evaluated by RMDT in the interpretation of the dynamic testing results. The foundation designer should determine if these considerations are applicable to this project and, if so, their impact on the foundation design.

Robert Miner Dynamic Testing, Inc. - PDIPLOT2 Ver 2017.2.58.5 - Case Method & iCAP® Results Printed: 14-October-2020 Test started: 05-October-2020

PPM, SAND ISLAND - PD 6.37, Pile 6-1C Ring

1 - Start of test on 10/5/2020 at 1:27 PM 2 - Restart after 14 minutes 58 seconds

3 - End of test on 10/5/2020 at 1:45 PM

BLC (bl/ft) Blow Count

EMX (k-ft) Max Transferred Energy

0 15 30 45 60

0 20 40 60 80

CSX (ksi) Max Measured Compr. Stress

STK (ft) O.E. Diesel Hammer Stroke

0 10 20 30 40 50

0 2 4 6 8 10

RX9 (kips) Max Case…