OCS Study

BOEM 2016-019

U.S. Department of the Interior

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

Pressure Wave and Acoustic Properties

Generated by the Explosive Removal of

Offshore Structures in the 

Gulf of Mexico
OCS Study

BOEM 2016-019

Published by

U.S. Department of the Interior

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

New Orleans, LA

March 2016

Pressure Wave and Acoustic Properties

Generated by the Explosive Removal of

Offshore Structures in the 

Gulf of Mexico

Authors

MJ Barkaszi

A Frankel

JS Martin

W Poe

Prepared under BOEM Contract

M13PX00068

by

CSA Ocean Sciences, Inc

8502 SW Kansas Avenue

Stuart, Florida 34997
iii

DISCLAIMER

This report was prepared under contract between the Bureau of Ocean Energy Management (BOEM) and 

CSA Ocean Sciences, Inc. This report has been technically reviewed by BOEM, and it has been approved 

for publication. Approval does not necessarily signify that the contents reflect the views and policies of 

BOEM, nor does mention of trade names or commercial products constitute endorsement or 

recommendation for use.

REPORT AVAILABILITY

To download a PDF file of this Gulf of Mexico OCS Region report, go to the U.S. Department of the 

Interior, Bureau of Ocean Energy Management, Environmental Studies Program Information System

website and search on OCS Study BOEM 2016-019.

This report can be viewed at select Federal Depository Libraries. It can also be obtained from the National 

Technical Information Service; the contact information is below.

U.S. Department of Commerce

National Technical Information Service

5301 Shawnee Rd.

Springfield, Virginia 22312

Phone: (703) 605-6000, 1(800)553-6847

Fax: (703) 605-6900

Website: http://www.ntis.gov/

CITATION

Barkaszi, M.J., A. Frankle, J. Martin, and W. Poe. 2016. Pressure wave and acoustic properties generated 

by the explosive removal of offshore structures in the Gulf of Mexico. U.S. Dept. of the Interior, 

Bureau of Ocean Energy Management, Gulf of Mexico OCS Region, New Orleans, LA. OCS 

Study BOEM 2016-019. 69 p. 
iv

ACKNOWLEDGMENTS

The project described in this report was funded by the Bureau of Ocean Energy Management 

(BOEM) through Order No. M13PX00068. We would like to acknowledge the important contribution of 

different people who have been very much instrumental to the realization of this project. The people are 

not presented here in view of the importance of their contribution, but rather in terms of the timing of 

their involvement in the program. We appreciated the help and comments from the BOEM and Bureau of 

Safety and Environmental Enforcement (BSEE) personnel of their Headquarters office in Herndon, 

Virginia, particularly Lisa Algarin, Contracting Officer (CO). We acknowledge BOEM Gulf of Mexico 

OCS Region Contracting Officer Representative (COR), Dr. Tré Glenn, for his input during the 

development of the project, assistance in the field work, and valuable commenting during the writing of 

the report. Also, we acknowledge the field support and Contract Inspector (CI) efforts provided by Doug 

Peter, T.J. Broussard, and Daniel “Herb” Leedy from BSEE Gulf of Mexico OCS Region, and Mark 

Belter from BOEM Gulf of Mexico OCS Region. We also acknowledge the field and logistic support 

from Explosive Services International (ESI) and, in particular, William Poe and Jason Poe. Their 

coordination with, and assistance to, the study team, BSEE, and project owners ensured safe and 

successful operations. 

Finally, we greatly appreciate and want to recognize the cooperation and essential contributions of 

Fieldwood Energy LLC; particularly, John Seeger, Vice-President of Decommissioning Operations, and 

Brandon DeWolfe, Facilities Operations Manager. Without Mr. Seeger’s and Mr. DeWolfe’s continuous, 

logistical coordination and generous support for the field measurement needs, the measurement activities 

described in this report would not have been possible.
v

CONTENTS

Acknowledgments.......................................................................................................................... iv

LIST OF FIGURES ....................................................................................................................... vi

LIST OF TABLES........................................................................................................................ vii

ACRONYMS............................................................................................................................... viii

1.0 Introduction ............................................................................................................................. 1

1.1 Theoretical Background................................................................................................ 5

1.2 Background of the Underwater Calculator ................................................................... 6

2.0 Methods................................................................................................................................... 8

2.1. Target Selection ............................................................................................................ 8

2.2 Field Detonation Design ............................................................................................... 9

2.2.1 Well and pile sever information...................................................................... 10

2.3 Field Data Collection .................................................................................................. 13

2.3.1 Acoustic Array................................................................................................ 13

2.4 Data Measurement ...................................................................................................... 15

2.5 Slant Range Calculation.............................................................................................. 18

3.0 Results................................................................................................................................... 20

3.1 Measurement Results.................................................................................................. 20

3.1.1 Measurement Results from WD40A Well Conductors .................................. 20

3.1.2 Measurement Results from WD40A Piles...................................................... 25

3.1.3 Measurements Results from WD40B Piles..................................................... 28

3.2 Analysis of Measurement Results............................................................................... 31

3.2.1 Peak Pressure .................................................................................................. 32

3.2.2 Impulse Data ................................................................................................... 35

3.2.3 Energy Flux Density Data............................................................................... 36

4.0 Discussion ............................................................................................................................. 37

5.0 Conclusions........................................................................................................................... 40

6.0 Literature Cited...................................................................................................................... 42

Appendix 1.................................................................................................................................... 44
vi

LIST OF FIGURES

Figure 1. Structure locations on the Gulf of Mexico Outer Continental Shelf (as of December 

2015)..........................................................................................................................................2

Figure 2. Typical platform or facility configuration found in the Gulf of Mexico OCS Region..............3

Figure 3. Approximate location of the current study in relation to previous Pressure Wave 

and Acoustic Properties (PWAP) measurement projects. .........................................................5

Figure 4. Theoretical decay rates or transmission loss rates.....................................................................6

Figure 5. Cutaway of well conductor components. ..................................................................................8

Figure 6. Top-down view of the project equipment arrangement showing the derrick barge 

with anchor lines, lift boat (recording platform), and platform...............................................10

Figure 7. Top-down perspective of the shot plan at WD40A well conductors.......................................11

Figure 8. Top-down perspective of the shot plan schematic for WD40A piles (A1 and C2).................12

Figure 9. Schematic drawing of array configuration. .............................................................................14

Figure 10. Sample data waveform showing five explosive events. ..........................................................16

Figure 11. Determination of the time constant. ........................................................................................17

Figure 12. Exponential fit-to-measured data. ...........................................................................................18

Figure 13. Slant range...............................................................................................................................19

Figure 14. Example of the spatial relationship for the pile locations determined from the 

platform blueprints and the sonar reflectors determined from the Mesotech data. .................19

Figure 15. Topside plan view of the main piles and well conductors of the WD40A platform. ..............21

Figure 16. Peak pressure measured on each sensor (black letters) as a function of the reduced 

range for the WD40A well conductor shots............................................................................22

Figure 17. Peak pressure measured on each sensor (black letters) as a function of the reduced 

range axis for the WD40A well conductor shots.....................................................................23

Figure 18. Pressure data for all 75-lb charges and linear curve fit for each UWC prediction 

(without sensors D and G).......................................................................................................24

Figure 19 Pressure data for all the 100-lb charges (without sensors D and G)........................................24

Figure 20. Pressure as a function of reduced range for the WD40A pile shots. .......................................26

Figure 21. Pressure data from the WD40A main piles, with the three near-bottom sensors 

removed...................................................................................................................................27

Figure 22. Top-down view of the positions of the five main piles and charge location for the 

WD40B platform.....................................................................................................................28

Figure 23. Measured peak pressure as a function of the reduced range axis for the WD40B pile 

shots.........................................................................................................................................29

Figure 24. WD40B pressure data with values less than 100 psi removed. ...............................................30

Figure 25. All of the 200-lb charge pressure data (with questionable values removed)...........................31

Figure 26. All pressure data as a function of the log scaled-weight axis..................................................32
vii

Figure 27. Curve-fit decay rate plots for combined data. .........................................................................32

Figure 28. All pressure data as a function of the reduced range...............................................................33

Figure 29. All pressure data as a function of the log scaled-weight axis, with the questionable 

data points removed.................................................................................................................34

Figure 30. Impulse data plotted as a function of the reduced range. ........................................................35

Figure 31. Impulse data plotted as a function of the reduced range, but with the questionable 

data points removed.................................................................................................................35

Figure 32. Energy flux density (EFD) plotted as a function of the reduced-range axis. ..........................36

Figure 33. Energy flux density (EFD) plotted as a function of the reduced-range axis, but with 

the questionable data points removed......................................................................................36

Figure 34. Sample detonation sequence (with sensors D and G removed) and pile location 

relative to sensor location........................................................................................................38

LIST OF TABLES

Table 1. WD40A well conductor shot parameters. ...............................................................................10

Table 2. WD40A pile shot parameters at 11:36 hours on 25 October 2014..........................................12

Table 3. WD40B pile shot parameters...................................................................................................13

Table 4. Transducer calibration data. ....................................................................................................16

Table 5. Comparison of parameters of past and current studies............................................................39
viii

ACRONYMS

AML above mudline

ARA Advanced Research Associates

BML below mudline

BNC bayonet needle connector

BOEM Bureau of Ocean Energy Managment

BSEE Bureau of Safety and Environmental Enforcement

C4 composition C-4 (explosive material)

CSA CSA Ocean Sciences, Inc.

dB decibels

DOI U.S. Department of the Interior

EFD energy flux density

ESA Endangered Species Act

GOMR Gulf of Mexico OCS Region

H6 composition H6 (explosive material)

Hz Hertz

ITS Incidental Take Statement

kHz kilohertz

kPa kilopascal

MAI Marine Acoustics, Inc.

MOPU mobile offshore production unit

MMPA Marine Mammal Protection Act

MMS Minerals Management Service

ms millisecond

mV millivolt 

NMFS National Marine Fisheries Service

NSWC (U.S. Navy) Naval Surface Warfare Center

NTL Notice to Lessees

OCS Outer Continental Shelf

OCSLA Outer Continental Shelf Lands Act

PETN pentaerythritol

PROP Platform Removal Observer Program

psi pounds per square inch

PWAP Pressure Wave and Acoustic Propagation

R range (spreading loss)

RL received level

s second

SL source level

SPL sound pressure level

TAR Technical Asessment Research Project

TL transmission loss

TLP tension leg platform

TNT trinitrotolulene

TTS temporary threshold shift

UWC underwater calculator

UWCv1 underwater calculator version 1

UWCv2 underwater calculator version 2

V volt

W weight (of charge)

WD West Delta OCS lease block area in Gulf of Mexico 
1

1.0 INTRODUCTION

Oil and gas operations on the Federal Outer Continental Shelf (OCS) result in the placement of 

structures, equipment, and moorings into and onto the seafloor. The companies are obligated to 

decommission the offshore infrastructure when their activities are completed and remove the 

components from the OCS, as mandated under regulatory and lease requirements. Decommissioning is 

the process of ending the operations, removing the equipment and facilities, and returning the seafloor 

to its pre-lease condition. Under the OCS Lands Act (OCSLA), the U.S. Department of the Interior’s 

Bureau of Ocean Energy Management (BOEM) establishes decommissioning obligations to which an 

operator must commit when they sign an offshore lease; these includes the requirement to apply for and 

obtain a permit for subsequent removal of wells and facilities. The U.S Department of the Interior’s 

Bureau of Safety and Environmental Enforcement (BSEE) is responsible for regulating the 

decommissioning of OCS facilities in accordance with 30 CFR 250 Subpart Q. The regulations and 

lease agreements typically require the operator to remove all structures within one year of lease 

termination or before termination of the lease if either the operator or BSEE deems the structure unsafe, 

obsolete, or no longer useful for operations. 

The OCSLA regulatory and lease requirements for decommissioning offshore platforms are 

designed to minimize the environmental and safety risks inherent in leaving unused structures in the 

ocean. Decommissioning an offshore platform generally entails plugging all wells supported by the 

platform, severing the well casings 15 feet below the mudline (BML), and removing the platform from 

its foundation by severing all bottom-founded components at least 15 ft BML. Additionally, the Bureau 

of Ocean Energy Management, Regulation and Enforcement (BOEMRE) published the Notice to 

Lessees and Operators (NTL) No. 2010-G05, “Decommissioning Guidance for Wells and Platforms,”

for lease holders in the Gulf of Mexico OCS Region (GOMR) to provide clarification and interpretation 

of Subpart Q requirements. The policy informs lease holders and operators of their responsibilities and 

provides definitions and timelines for decommissioning idle wells and associated platforms. 

Decommissioning idle wells and inactive platforms in a timely manner reduces potential environmental 

and navigational risks on the OCS. 

Based on the most recent available data from BSEE (January 2016) (USDOI, BSEE, 2016), there 

are more than 2,325 existing structures the GOM OCS (Figure 1 has locations as of December 2015). 

The four main types of structures found on the GOM OCS are multi-leg platforms (67%), caissons 

(23%), well protectors (8%), and floating facilities (2%), which includes spars, tension leg platforms 

(TLPs), and mobile offshore production units (MOPUs). The majority of structures are located off the 

coast of Louisiana in less than 300 ft of water. 
2

Figure 1. Structure locations on the Gulf of Mexico Outer Continental Shelf (as of 

December 2015).

As noted above, the most common type of offshore structure in GOMR is the conventionally piled 

platform (Figure 2). These structures are secured to the seafloor by steel pipes called piles (or pilings) 

driven through the legs of a tubular frame called a jacket. Only the upper portion of the jacket is visible 

above the water surface. Piles have varying diameters and wall thicknesses, and their number can vary 

from three to eight or more, depending on the platform’s configuration and location on the OCS. The 

pile-to-jacket annulus in conventionally piled platforms is sometimes grouted. In most cases, several 

wells are drilled through long tubes, called conductors, placed through slots in the jacket. There can be 

as few as one or two wells or as many as sixty. The outermost pipe, called the drive pipe, may contain 

several inner conductors called casings.
3

Figure 2. Typical platform or facility configuration found in 

the Gulf of Mexico OCS Region.

The methods used to sever bottom-founded components and other structural members will vary by 

facility, water depth, and other operational factors; however, BSEE categorizes the options as either 

mechanical or explosive severance. Currently, both severance methods are used equally. 

Mechanical severance includes abrasive-water jets, sand-cutters, diamond-wire saws, carbide

cutters, shears, and guillotine saws. This method generally proceeds more slowly than explosive 

severance options, because each target must be cut separately, and the logistics require additional 

personnel (often divers), or bulky support equipment is needed. Historically, the slower speed, 

additional personnel, and support spread result in more injuries and higher costs compared to explosive 

severance.

Explosive severance relies on the use of specially designed bulk or shaped charges. Charges are 

made up of explosive material with specific properties (i.e., velocity, density, brisance, specific energy, 

and weight strength) to produce enough stress, upon detonation, to completely sever the platform’s 

bottom-founded components. The charge is generally deployed from above the water surface inside the 

pile or conductor and set at various depths to comply with the minimum 15-ft BML requirement and 

reshoots, if required. Current BSEE policy and the most recent Endangered Species Act (ESA)

Biological Opinion allow operators to use charges with explosive weights up to 500 lbs; however, 

successful severance is typically made with smaller charges, from 50 to 200 lbs. Explosives allow 

multiple targets to be cut at once and typically require fewer technicians to deploy and detonate, which 

has historically resulted in fewer human injuries and lower costs compared to mechanical severance. 

Though mechanical severance methods pose few environmental concerns, the use of underwater 

explosives has the potential to impact marine life, particularly, marine mammals, sea turtles, and fish, 

which can be harmed by explosive overpressures. Noise levels during these detonations may pose a 
4

temporary acoustic disturbance to marine species. BSEE, as the permitting authority, and the operators 

who carry out the decommissionings, must do so in compliance with the ESA and the Marine Mammal 

Protection Act (MMPA). It is unlawful to “take” ESA-listed species; meaning it is unlawful to injure or 

harass a species listed as endangered or threatened under the ESA. BOEM and BSEE are subject to 

consultation requirements that may result in an Incidental Take Statement (ITS) and terms and 

conditions to be placed on decommissioning operations. In the GOMR, BSEE also coordinates with the 

National Marine Fisheries Service (NMFS) to petition for incidental-take rulemaking for marine 

mammals under the MMPA, which allows for subsequent Letters of Authorization (LoAs) to be issued 

to operators by NMFS for take coverage.

In the past, NMFS typically applied take-threshold criteria for explosives from models that were 

developed for the incidental-take authorization of U.S. Navy’s shock trials. In these, large, open-water 

charges of 5,000 to 10,000 lbs are detonated within close proximity of new classes of warships to assess 

how well the ship can withstand damage and how well the crew can respond to mass system casualties 

(Department of the Navy, 1998, 2001). The conservative nature of these models resulted in high

potential take estimates and large exclusions zones, on the order of 2 km or more, to be monitored 

during blasting operations. Conventionally, these conservative predictions of the impact zone have 

been used to satisfy MMPA and ESA requirements. However, explosive severance and, particularly,

BML detonations are likely to produce lower pressure levels at the same propagation distances than 

open-water shock trial configurations, due to absorption, attenuation of energy by sediments, and the 

confinement of the explosion within well casings and platform piles. Conservative take estimates and 

large exclusion zones have been used for explosive severance because of a wide range of probabilistic 

error associated with insufficient in situ measurements from which to calculate the most plausible

impact zone.

Previous explosive-severance studies conducted by the U.S. Department of the Interior’s Minerals 

Management Service (MMS, now BOEM and BSEE) focused on determining the potential impact on 

the marine environment and increasing the accuracy of predicting pressure waves and acoustic levels

radiating from blast events. By collecting acoustic data under various settings (i.e., varying cut depth, 

charge size), more accurate estimates of Pressure Wave and Acoustic Propagation (PWAP) can be 

calculated so that the agencies can apply appropriate mitigations to protect marine mammals and sea 

turtles, and also optimize operations (safety and efficiency) during detonations. 

Before this study, MMS’s Technology Assessment and Research (TAR) Project funded three 

similar, in situ PWAP projects working with various consultants and operators (Figure 3). The first, 

TAR Project No. 118, was overseen by the Department of the Navy’s Naval Surface Warfare Center 

(NSWC). During the winter of 1988, it was carried out in coordination with MMS personnel and the 

Exxon Corporation, who measured 27 separate detonations at West Delta (WD) Block 30 (Connor, 

1990). The Connor Study, as it is commonly called, included a set of developed, similitude equations, 

which were seen as the standard for calculating pressure ranges until NSWC questions the 

measurement. The second, TAR Project No. 429, was centered on developing improved linear shaped 

charge cutters; the project was modified during field testing to allow the deployment of an acoustic 

array to measure pressure wave characteristics (Saint-Arnaud et al., 2004). The severance/measurement 

activities were conducted in November 2003 at South Timbalier (ST) Block 21 structures. The third, 

TAR Project No. 570, was developed in 2006 to determine the effect of placement depth of the 

severance charges (15, 20, 25, and 30 ft BML) on the recorded PWAP (Poe et al., 2009). The in situ

testing took place at two locations: in Eugene Island Block 128 during July and August 2007 and in 

East Cameron Block 32 in August 2008. 
5

Figure 3. Approximate location of the current study in relation to previous Pressure 

Wave and Acoustic Properties (PWAP) measurement projects. 

The current study was developed to be a successive project and applied a comparable methodology 

and equipment used in previous explosive severance studies to collect measurement data. The primary 

objective of this study, where possible, was to obtain additional in situ data points and charge 

parameters necessary to fill in information gaps from the previous projects. A secondary objective of 

this project was to provide supplemental data for validating and fine tuning previously-developed 

modeling used to establish impact zones for mitigative monitoring needed during decommissioning 

projects using explosives. 

1.1 THEORETICAL BACKGROUND

A review of the theoretical background on shock wave attenuation and underwater propagation is 

provided in Section 2 of the TAR Project No. 570 report (Poe et al., 2009). A simplified explanation of 

the relevant concepts is offered here. The most basic form of the sonar equation can be used to outline 

the relevant issues (Eq 0).

RL = SL – TL

where RL is the received level, SL is the source level, and TL is the transmission loss. Source level 

is the amplitude of the explosion at a nominal range (typically 1 m). Transmission loss is the amount of 

amplitude decrease with range as the shock wave propagates outward. Subtracting TL from SL gives 

the received level at that particular range.

Safety ranges for marine protected species are set by NMFS at a conservative distance greater than 

that needed for the RL to meet the regulatory threshold (e.g., 23 pounds per square inch [psi]). The 

source level of an explosive charge in a free field is readily determined by its composition and weight.

However, when a BML charge is encased in a pile, the sediment and the pile will absorb some of the 

energy produced by the explosion. The effective source level is reduced and was verified in previous 

studies (Poe et al., 2009, Connor 1990; Continental Shelf Associates, Inc., 2004; Saint-Arnaud et al.,

2004; Kaiser et al., in prep; Frankel and Ellison, 2004; Dzwilewski and Fenton, 2003; Dzwilewski,

2014). 

Once the shock wave enters the water column, its amplitude will attenuate with range (R). This is 

known as spreading loss or the decay rate. In a free field, the pressures of acoustic waves decay at a 
6

rate of R

-1

(decay rate of spherical spreading). The theoretical spreading loss for an open-water 

explosion is R

-1.13 (Arons et al., 1950), or slightly higher than spherical spreading. These decay rates 

are shown in Figure 4 with both axes in logarithmic form. In this representation, the slope of the line 

can be used to measure the value of the exponent.

Figure 4. Theoretical decay rates or transmission loss rates. 

In pure spherical spreading, the pressure drops as the reciprocal of R. The theoretical 

decay rate for explosions is R-1.13. The slope of the pure spherical spreading line is -1 and 

the slope of the theoretical explosion line is -1.13.

1.2 BACKGROUND OF THE UNDERWATER CALCULATOR

In 2002, Applied Research Associates, Inc. (ARA) was contracted by MMS to develop a method to 

determine the shock wave propagation in the water column due to the underwater detonation of an 

explosive-severance charge. The research goal was to assess the impact that the detonations would 

have on marine life by developing a model that accurately estimates the shock effects caused by the 

detonation of a BML explosive charge inside a pile, leg, conduit, or other structural element of an oil 

and gas platform. The resulting model based on this methodology is referred to as the Underwater 

Calculator (UWC). The UWC is a spreadsheet-based tool that calculates the underwater shock, 

specifically the peak pressure, impulse, and energy flux density expected to result from the explosive 

detonation charges during explosive severance work. The tool is used to calculate the range from the 

explosive to a specified peak shock pressure and energy level that may result in impacts to marine life.

Version 1 of the UWC (UWCv1), published by ARA in 2003 (Dzwilewski and Fenton, 2003),

calculated the propagation of acoustic energy from the explosive severance as a function of the pile

diameter, pile wall thickness, and weight of the explosive used (25, 50, and 100 lbs). Numerical 

simulations using a representative distance of 30 m and 25-millisecond (ms) model run duration were 

performed to determine the amount of energy that is coupled to the water. The 30-m distance was 

chosen to be more than twice (2.3 times) the extent of the strong shock or nonlinear region as cited in 

Richardson et al. (1995). Each calculation was run out to a simulation time of 20 to 25 ms, which is the 

time it takes for a shock wave to propagate 30 to 37 m through water.
7

The simulations showed that less energy (30% to 70% reduction) is transferred to the water when 

the severance charge is confined than when detonated in open water. The inertial properties and 

structural strength of the pile and substrate must be overcome by the explosive charge before excess 

energy coupling into the surrounding water. The pile confinement has a greater effect than the substrate 

on the loss of energy coupling to the water because of the greater strength and density of the pile 

material. Some energy (typically less than 5%) is lost due to pressure wave propagation through the

water trapped inside the pile. This minimal amount of energy propagates up through the pile opening 

and into the air (Dzwilewski and Fenton, 2003). The least amount of energy transmission into the water 

occurs when the explosive is placed BML within a pile, because this augments the effect of both the 

pile and the substrate on energy transmission.

MMS (now BOEM and BSEE) used the UWCv1 to calculate impact zones critical to protected 

species and for mitigation planning for the 2005 Programmatic Environmental Assessment (US DOI 

MMS, 2005). That information and the in situ comparisons done during TAR 429 (Saint-Arnaud et.al, 

2004) were also used in the 2005 MMPA take authorization (Federal Register, 2008). When the 

UWCv1 was released, the MMPA take criterion was defined as a peak pressure greater than 12 psi for 

an explosive source. The NMFS has since revised this criterion and determined that temporary 

threshold shift (TTS) may occur at peak pressure levels greater than 23 psi (Federal Register, 2014).

To operate UWCv1, the user inputs a geometric profile that consists of explosive depth, slant range,

and receiver depth; and physical properties, including pile diameter, pile wall thickness, explosive 

weight, and explosive type. The model offers several options in the type of explosives used: 

trinitrotolulene (TNT), composition H6 (H6), Pentaerythritol tetranitrate (PETN), composition C-4 

(C4), or a user-defined explosive.

For the forward calculation, the outputs provided by the model are peak pressure, impulse 

(see Equation 1 in Dzwilewski and Fenton, 2003), energy flux density (see Equation 2 in Dzwilewski 

and Fenton, 2003), and explosive time constant at the specified point in the water column. The 

backward (or inverse) calculation provides the slant range for a specified energy flux density (EFD), 

decibel (dB) value, or pressure input.

UWC Version 2 (UWCv2), an updated version of the UWCv1, released by Dzwilewski (2014),

accounts for the abovementioned newer take criterion of peak pressure levels greater than 23 psi and 

uses models of peak value as a function of range that have been refined and verified based on in situ

data. These in situ data were collected as part of TAR Project No. 570 (Poe et al., 2009) and data 

collected by Connor (1990) during TAR Project No. 118. The models relating to TAR Projects No. 118 

and No. 570 were developed by determining the best curve fit to each data set.

The TAR Project No. 570 data were collected for charges set at 15, 20, 25, and 30 ft BML during 

20 internal (pile) severance detonations, with charges ranging from 25 to 145 lbs, and two open-water 

detonations using 5-lb charge weights. The conclusions drawn from the data indicate that increasing 

the depth BML of the explosive charge increased the attenuation of the pressure wave/acoustic energy 

and resulted in a size reduction of the marine protected species impact zones. Similarly, the TAR 

Project No. 118 (Connor, 1990) data were collected for main pile charges severed BML at depths of 8, 

16, and 26 ft. Jacket leg and skirt piles were severed, along with well conductors. Charge weights of 

25, 38, and 50 lbs were used. The data showed that, at 400 ft from the platform, the shock parameters 

were less than 10% of the values expected from an open-water detonation at the same range and same 

explosive weight.

A primary objective of this study was to obtain in situ data from decommissions of structures and 

charge parameters necessary to fill in any data gaps from the previous studies. To collect acoustic 

measurement data, this explosive severance study applied comparable methodologies and equipment as 

used in the previous studies. The project goal was to provide supplemental data for the validation and 

fine-tuning of the models used to develop the UWC. These new data yield information about the 

accuracy and robustness of the UWC Versions 1 and 2.
8

2.0 METHODS

2.1. TARGET SELECTION

Platform targets were selected based on consultation with BSEE and platform owner and operators

to identify platforms that would be the best to use for model verification while still conforming to their 

decommissioning schedule. Each well and pile has specific physical properties that can influence the 

sound propagation. For well conductor severance, the charge is confined by the outermost drive pipe

(caisson), the conductor pipe, and, in some cases, an inner casing pipe (Figure 5). For pile severance,

the charge is confined by an outer jacket leg and an inner pile. The jacket leg and pile assembly are 

considered as one structure for the input parameters of diameter and wall thickness. The goal was to 

choose targets that would allow numerous detonations and charge configurations, such that the data 

collected would maximize charge types and BML configurations identified as high priority data gaps 

for refining the UWC. Targets were prioritized to increase the number and type of detonation (shot) 

measurements as inputs to the UWC, strengthening the UWC’s value for potential use in estimating 

peak pressure and protected species safety zones during decommissioning activities that use explosive 

severance.

Figure 5. Cutaway of well conductor components.

Potential structures for removal were identified that offered an opportunity for at least 7 to10

detonation events with minimal mobilizations. Specifically, the availability of both well conductor and 

pile detonations, at least 15 ft BML, and requiring 100 lbs or more of explosives. Two appropriate 

platforms were selected: West Delta Block 40, platforms A and B (WD40A and WD40B). The 
9

platform WD40A was located in the West Delta Block of the Gulf of Mexico at 

29.04084020N/89.47700600W. The target consisted of eight well conductors and six piles located in 

92 ft of water. Each conductor was 24 to 28 inches in diameter and had a wall thickness of 0.5 inches.

Each pile was 36 inches in diameter, with a wall thickness of 1.75 inches.

The platform WD40B was also located in the West Delta Block of the Gulf at 

29.04090000N/89.48190000W. The target consisted of five piles located in 92 ft of water. The piles 

were 36 inches in diameter with a wall thickness of 2.25 inches.

2.2 FIELD DETONATION DESIGN 

Explosive charges made of composition B explosives were used to sever the piles and well

conductors of WD40A and WD40B. During the preparation of these structures for removal, welders 

cut deck with associated topsides (equipment and helicopter pad) from the jacket approximately 12 ft 

above the waterline and transferred the assembly to a material barge using the main crane on the derrick 

barge. Deck removal deck allowed access to high pressure jet cleaning of the internal well conductors

and piles to the specified severance cut depth. The specific structures removed during this test were 

permitted by BSEE for 200-lb explosive charges detonated at 15 ft BML. The explosive severance

charges were lowered by crane to the predetermined depth BML and secured. The charges were then 

primed (delay detonator attached), and the derrick barge was moved to a safe location (at least 500 ft 

away) from the platform jacket. NMFS observers from the Platform Removal Observer Program 

(PROP) then performed an aerial observation by helicopter for 45 minutes. Aerial observation patterns 

make a clockwise spiral from the platform out to the edge of the impact zone (NOAA, 2006); or 3,086

ft for this removal scenario. Halfway through the survey, the observation aircraft periodically diverges

from the spiral pattern to scan outside the perimeter of the impact radius to confirm that no animals are 

approaching the impact zone. The NMFS observers completed the required observation period and

confirmed that the observed area around the platform was clear of marine mammal and sea turtle 

species immediately before detonation. 

Upon NMFS clearance confirmation, the explosives were detonated using a minimum 1-s delay 

detonator between each charge. The derrick barge was then moved back into position (next to the 

platform) for rigging and lifting the severed conductor wells and platform jacket (Figure 6). The

conductor wells were pulled out of the slots first and then the entire jacket structure was removed from 

the seabed. The decommissioned platform jackets and conductor wells were fastened to a materials 

barge and transported to an onshore disposal facility.
10

Figure 6. Top-down view of the project equipment arrangement showing the derrick 

barge with anchor lines, lift boat (recording platform), and platform. 

This placement was similar for both removal sites WD40A and WD40B.

2.2.1 Well and pile sever information 

A total of eight well conductors at the WD40A platform were severed at 13:01 hours on 24 October

2014 (Table 1 and Figure 7). There was a 1-s delay between each shot. 

Table 1. WD40A well conductor shot parameters.

Shot Target 

Name

Charge 

Weight 

(lb)

Charge 

Depth BML 

(ft)

Outer Drive 

Pipe Diameter 

(in.)

Conductor 

Diameter

(in.)

Casing

Diameter 

(in.)

Wall 

Thickness 

(in.)

1 Well A-11 75 25 24 9.625 n/a 0.5

2 Well A-4 100 25 24 10.75 7.625 0.5

3 Well A-9 100 25 24 10.75 7.625 0.5

4 Well A-2 100 25 24 13.375 10.75 0.5

5 Well A-7 100 25 24 16 10.75/7.625 0.5

6 Well A-8 75 15 24 10.75 n/a 0.5

7 Well A-1 100 15 28 9.625 n/a 0.5

8 Well A-3 75 15 24 10.75 n/a 0.5

BML = below mud line; n/a = not applicable.
11

Figure 7. Top-down perspective of the shot plan at WD40A well conductors.

A1 and C2 are the platform support legs; the arrow points to the location of the acoustic sensor 

array attachment, the reference point is the location of the pre-detonation calibration charge.

The six piles at platform WD40A were severed at 11:36 hours on 25 October 2014. The following 

list describes each pile and the order of detonation (Table 2 and Figure 8). There was a 2-s delay

between each shot.
12

Table 2. WD40A pile shot parameters at 11:36 hours on 25 October 2014.

Shot Target Name Charge Weight 

(lb)

Charge depth 

BML (ft) Diameter (in.) Wall Thickness (in.)

1 A2 200 20 36 1.75

2 A1 200 20 36 1.75

3 B1 200 20 36 1.75

4 C1 200 20 36 1.75

5 C2 200 20 36 1.75

6 B2 200 20 36 1.75

Figure 8. Top-down perspective of the shot plan schematic for 

WD40A piles (A1 and C2).

The arrow points to the location of the acoustic sensor array attachment, 

the reference point is the location of the pre-detonation calibration charge.
13

Five piles of the WD40B platform were severed on 28 October 2014 (Table 3) at 15:11 with a 2-s

delay between shots. Pile A2 was not severed due to problems encountered while jetting (cleaning) 

piles for charge placement.

Table 1. WD40B pile shot parameters.

Shot Target Name Charge Weight 

(lb)

Charge depth 

BML (ft)

Pile Diameter 

(in.)

Wall Thickness 

(pile and jacket leg) 

(in.)

1 A1 200 20 36 2.25

2 B1 200 20 36 2.25

3 C1 200 20 36 2.25

4 C2 200 20 36 2.25

5 B2 200 20 36 2.25

2.3 FIELD DATA COLLECTION

2.3.1 Acoustic Array

The sensor array used to collect these data was based on the successful designs used in the previous 

TAR Projects No. 429 and No. 570 (Saint-Arnaud et al., 2004; Poe et al., 2009). CSA and Marine 

Acoustics, Inc. (MAI) constructed a transducer array consisting of 12 PCB Piezotronics, Inc. (PCB)

W138A02 Tourmaline ICP®underwater blast sensors. These sensors have a measurement range of 

1,000 psi (6,895 kilopascals [kPa]), sensitivity at (±15%) 5 millivolt (mV) psi-1(0.73 mV kPa-1), a lowfrequency response of (-5%) 2.5 Hertz (Hz), and resonant frequency of ≥ 1,000 kilohertz (kHz).

Sensors included measured-to-length marine waterproof cabling that terminated with a bayonet 

needle connector (BNC) installed by the manufacturer. The 12 individual sensors were powered by 

three four-channel PCB 482C05 charge amplifiers. A Yokogawa DL850 data acquisition and analysis 

system was used to process, display, and record data. This Yokogawa was equipped with six, 2-channel 

1 MS s

-1

, 16-bit, high-speed modules (model number 701251) that were used to provide analog to 

digital conversion with sufficient dynamic range and temporal resolution.

To capture the desired data for each blast configuration, three near-field acoustic arrays were 

deployed that consisted of three transducers each and three far-field acoustic arrays were deployed that

consisted of one transducer each that were located at predetermined depths (proportional to the water 

depth and platform structure). The array of sensors is diagrammed in Figure 9.
14

Figure 9. Schematic drawing of array configuration. 

Sensor cables are not shown here; however, a single cable ran from each sensor to the 

electronics on the lift boat. The location of the reference origin of the array is indicated by an 

arrow and “origin” in red.

The array methodology and deployment configuration was similar to the methodology used during

TAR Project No. 570 (Poe et al., 2009). The vertical arrays were deployed from a small watercraft 

launched from the lift boat. Each array was attached to a 4-mm braided plasma line equipped with a 

sonar reflector and anchor. Once the lift boat was positioned, a small workboat (approximately 15 ft) 

was used to attach the coated steel cable (strong line) to the designated pile of the target platform. The 

strong line was stretched taut from the target structure to the lift boat that provided housing for the 

recording equipment. The strong line had floats placed at the locations where each downline or anchor 

line was placed. Each downline assembly consisted of an anchor, a sonar reflector, the vertical 

non-stretch plasma line, and appropriate number of cabled sensors (Figure 9). The downline assembly 

was installed by lowering the anchor to the bottom, then attaching the plasma line to the horizontal 

strong line. The sensor cables were routed along the strong line, and the cable connectors were attached 

to the data acquisition equipment on the lift boat. This procedure was repeated for each downline 

assembly and sensor cable.

Once the workboat was retrieved, BSEE personnel deployed the Mesotech MS 1000 sector 

scanning sonar to record the positions of the sonar reflectors located at the bottom of each downline. 

The sonar data, combined with the known positions of the surface floats, were later used to calculate the 

three-dimensional (3D) coordinates of each sensor.
15

Near the bow rail of the lift boat (recording location) was an 8 ft x 10 ft steel container, which was

used as a weatherproof equipment lab. The Yokogawa and signal conditioners were located in this lab 

as well as storage for supplies and backup equipment. The cables with BNC connectors from each 

sensor were run over the bow and into the lab. Power for the equipment was provided by a combination 

of a small generator, 12-V batteries, and ship power. 

Before each decommissioning event, the charge weights were input into UWCv2, using the openwater setting, to predict the amplitude of the signal at each sensor. These predictions determined the 

appropriate sensitivity setting for each data channel of the Yokogawa recorder for each explosive 

severance event to ensure that the incoming data signals did not exceed the voltage range of the 

recorder, a condition known as “clipping”.

Before each detonation, the derrick barge backed away from the target platform, and the lift boat 

was raised several feet above the sea surface for safety and to protect the ship systems from the blast. 

Raising the lift boat pulled the strong line taut and therefore provided and maintained accurate spacing 

in the downlines. A small calibration charge consisting of 2 ft of detonation cord was used to verify 

that the sensor and data recording equipment were working properly before each decommissioning 

event. This ensured that data collection equipment was functioning properly before the explosive 

charges were detonated.

Before each explosive severance event, the field acoustician and BSEE personnel coordinated the

protocol and timing between charges with the explosives director. When all preparations were 

finalized, the explosives director gave a two-minute detonation warning notice over the radio. The 

Yokogawa recorder data acquisition process was started at least 30 s before the detonation event. 

Explosive charges were spaced 1 s apart for the well conductor severance event at WD40A and 2 s 

apart for the pile severance events to allow reverberation to attenuate before the next explosive charge 

detonated.

2.4 DATA MEASUREMENT

The Yokogawa recorder was stopped shortly after detonation. The acquired data were transferred 

via secure digital card to a Dell Dimension workstation, where they were converted from the 

proprietary Yokogawa format (WDF) into a standard .wav audio file format using the Yokogawa 

supplied WDFcon utility.
16

The remaining analyses were conducted on a MacBook Pro using Matlab 2014a (Mathworks, 

2014). The voltage data were loaded and converted into pressure values (psi) using the calibration 

values provided by PCB (Table 4). A sample recording is shown in Figure 10, where five discrete

explosion signals can be seen clearly.

Table 2. Transducer calibration data.

Yokogawa 

Channel

Signal 

Name

Distance AML 

(ft)

Cable 

Length (ft) PCB Tranducer Serial Number

Sensitivity 

(mV/psi)

1 A 5 450 138A01 10132 5.007

2 B 45 425 138A01 10140 4.919

3 C 80 400 138A01 10139 5.034

4 D 5 400 138A01 10138 5.033

5 E 45 375 138A01 10137 5.284

6 F 80 350 138A01 10135 5.057

7 G 5 375 138A01 10136 4.704

8 H 45 350 138A01 10134 5.191

9 I 80 325 138A01 10144 5.009

10 J 80 300 138A01 10142 5.003

11 K 80 250 138A01 10143 4.880

12 L 80 200 138A01 10141 5.138

AML = above mudline; mV = millivolt; PCB = PCB Piezotronics, Inc.; psi = pounds per square inch.

Figure 10. Sample data waveform showing five explosive events.
17

The following amplitude metrics were generated for each signal on each recording channel:

(1) Peak pressure (reported in psi and megaPascals)

(2) Impulse (reported in psi-seconds and kiloPascal-seconds)

(3) Energy flux density (EFD; reported in psi-inch and kiloPascal-meter)

Peak pressure is simply the maximum pressure value for each signal on each channel. 

Impulse (I) was calculated with Equation 1:

I(t) = ∫ P

τ

0

(t)dt (1)

where P is pressure and τ (tau) is the integration time of the impulsive signal. The integration time was 

set as five times the time constant (Swisdak, 1978). The time constant is defined as the time needed for 

the peak pressure (Pm) to decay to the defined value of Pm/e, where e = ~2.718. Figure 11 illustrates

the procedure to determine the time constant (redrawn from Swisdak, 1978). The solid line represents 

exponential decay. As per Swisdak (1978), exponential decay is expected to occur until about one time 

constant (θ). After that, the actual decay in pressure is expected to occur more slowly, shown as the 

dashed line.

Figure 11. Determination of the time constant.

The EFD was calculated using Equation 2:

Ef

(t) = ρ0

−1

c0

−1

∙ ∫ p

2

τ

0

(t)dt (2)

The τ (tau) value derived for the impulse calculation was used in this calculation. 
18

Moving from theory to measured data introduced complexities in the analysis of measurement 

results. The measured signals frequently had multiple peaks or otherwise did not conform to the 

theoretical decay pattern, complicating the determination of the value of theta. An exponential decay 

function was fit to the pressure time series (Figure 12). The time constant was taken as the time 

required for the fitted exponential decay function to reach the criterion value (Pm/e). If the recorded 

time-pressure series did not support the curve fit, the impulse measurement for that signal was 

discarded. 

Figure 12. Exponential fit-to-measured data. 

The blue line shows the measured pressure values, and the red line shows the 

exponential fit to the data.

2.5 SLANT RANGE CALCULATION

The precise manner of array deployment enabled an accurate estimation of the 3D positions of the 

sensors and the explosive charges. Thus, the distances between them in the X, Y, and Z planes were

calculated, and the total slant range (Figure 13) from each charge to each sensor was determined. In 

addition to the positional data provided by the blueprints of each platform, the origin of the local 

coordinates for each platform was recorded at the attachment point of the strong line to the designated 

pile (seen in Figure 9). The dimensions of the platform and the BML depth were then used to 

determine the 3D locations of the charges.
19

Figure 13. Slant range.

The Mesotech data were used to calculate the horizontal range and bearing of each sonar reflector 

from the position of the pile to which the strong line had been attached. The assumption was made that 

the surface float was directly above the sonar reflector. Thus, the platform geometry and Mesotech data 

provided the inputs for the X and Y planes. An example of this is shown in Figure 4. The distance in 

Z direction was the charge depth, added to the measured height of each sensor above the seafloor. The 

X, Y, and Z distances were used to calculate the slant range from each charge to each sensor.

Figure 14. Example of the spatial relationship for the pile locations determined 

from the platform blueprints and the sonar reflectors determined 

from the Mesotech data.
20

3.0 RESULTS

Data are presented as both a function of slant range and the reduced range (Urick, 1983). The 

reduced range is the range divided by the cube root of the charge weight. In a free-field environment,

the received level of peak pressure, from a charge of weight, W, is defined as:

log10(Peak Pressure) = Constant − 1.13 log10 (R ∙ W

−1

3

⁄

)

Plotting the peak pressure compared to the reduced range allowed simultaneous comparison of data 

from different explosions with varying charge. When plotted as a function of slant range, data from 

different size charges must be considered separately.

Field measurements were compared with various predictions produced by the UWCv1 and 

UWCv2. UWCv1 requires specification of pile parameters (diameter, thickness), whereas UWC v2 has 

a predetermined set of scenarios (e.g., main pile Connor or well conductor, TAR Project No. 570) that 

incorporate values for these variables. The UWCv2 predictions included those for a free-field 

explosion, the main pile, and the well conductor with the Connor and TAR Project No. 570 options.

UWCv1 predictions were made using the exact values from each explosion.

3.1 MEASUREMENT RESULTS

Summaries of the results for each individual detonation event (WD40A well conductors, WD40A 

piles, and WD40B piles) using UWCv2 are provided in Appendix 1. A detailed list of sensor 

measurements for each shot is provided in the Appendix.

3.1.1 Measurement Results from WD40A Well Conductors

The first measurements were made on 24 October 2014 when the well conductors were explosively 

severed. Figure 15 illustrates the geometry of the well conductor, piles, and locations of the pile 

charges for platform WD40A. Data were collected on 11 of 12 of the sensors. One of the sensor cables 

was accidently cut during deployment before the explosives were detonated. This cable was repaired 

and the sensor was returned to service the following day.
21

Figure 15. Topside plan view of the main piles and well 

conductors of the WD40A platform.

The main piles are slanted at a slope of 10%, so the positions of the piles at the surface and the 

positions of the charges BML are offset. The positions of the main piles are shown at the 10-ft

elevation, as taken from the original plans (distances are in feet). The positions of the charges BML 

were determined from the slope of the main piles (10%).

The final charge locations and configurations that were used as input for the UWCs are shown in 

Tables 1 through 3. The pressure results for each detonation shot are shown in Figure 16.
22

Figure 16. Peak pressure measured on each sensor (black letters) as a function of 

the reduced range for the WD40A well conductor shots. 

A log-log fit of the data is shown as a green line.
23

The data in Figure 17 show what appear to be two anomalous data points in each of the detonations 

shots (e.g., the two data points in the lower left corner for shot number 8). These anomalous points

were recorded on the near-bottom sensors D and G. Figure 16 shows the same data with these two 

sensors removed. The relationship between pressure and the reduced range axis is much more 

consistent. Potential reasons for the anomalous data points are discussed in Section 4.0. 

Figure 17. Peak pressure measured on each sensor (black letters) as a function of the 

reduced range axis for the WD40A well conductor shots. A log-log fit of the 

data is shown as a green line.
24

The data from the 75-lb charges (n = 3) from the WD40A well conductor detonations (open circles)

were combined (Figure 18). The predictions of the UWC (Versions 1 and 2) are plotted for 

comparison. The long red line in this (and the following) figure represents the linear curve fit to the 

measured data, which has a slope of -1.042. The UWC predictions and the curve-fits represent the 

decay function of the pressure amplitude with range. The 100-lb charge data from the 100-lb charges (n

= 5) from the WD40A well conductor shots were also combined (Figure 19). The slope for the line 

fitted to those data is -1.121.

Figure 18. Pressure data for all 75-lb charges and linear curve fit for each UWC 

prediction (without sensors D and G). Slope (red line) is -1.042.

Figure 19 Pressure data for all the 100-lb charges (without sensors D and G). 

Slope (red line) is -1.121.
25

Both Figures 18 and 19 show that the 75- and 100-lb data (red line) have respective decay rates of 

R

-1.04 and R-1.21, which are similar to those of the open water, the UWCv1 (gray line), and the UWCv2 

TAR 570 (pink line) predictions (R-1.13). The amplitude of the measured data is intermediate between 

the two predictions. 

3.1.2 Measurement Results from WD40A Piles

The second data measurements were made on 25 October 2014 when the main piles of WD40A 

were severed. Data were collected from 12 of the 12 sensors. The parameters describing these shots

are shown in Table 4. The pressure results for each explosion are shown in Figure 20.

Again, there appear to be anomalous data points in the lower left-hand corner of these plots. These

data were recorded on the near-bottom sensors A, D, and G. Figure 21 shows the same data set with 

these three sensors removed. The correspondence to a linear relationship is much better among the 

remaining data channels.
26

Figure 20. Pressure as a function of reduced range for the WD40A pile shots.
27

Figure 21. Pressure data from the WD40A main piles, with the three near-bottom sensors 

removed.
28

3.1.3 Measurements Results from WD40B Piles

The second structure was removed on 28 October 2014, when five of the six main piles were shot. 

One pile had an obstruction that did not allow for the BML placement of the explosive charge. Data 

were collected on all 12 sensors. The geometry of the main piles is shown in Figure 22, where the 

location of the piles in horizontal space is shown relative to the charge locations (measured in feet). 

Only five piles are illustrated, because one pile was not severed explosively. The parameters describing 

these shots are shown in Table 4. The pressure results for each explosion are shown in Figure 23.

Figure 22. Top-down view of the positions of the five main piles and charge location for 

the WD40B platform. 

The positions of the main piles are shown at the 10-ft elevation, as per the original plans. The 

positions of the BML charges were determined from the slope of the main piles (12.5%).
29

Figure 23. Measured peak pressure as a function of the reduced range axis for the 

WD40B pile shots.
30

The data from WD40B show fewer apparently anomalous data points. There was no consistent 

pattern as to which sensor produced the very low values. At the WD40A locations, all of the 

anomalously low values were measured with the near-bottom sensors. At WD40B, there was no such 

obvious pattern. The most aberrant points were those with values less than 100 psi. Figure 24 presents 

these data with five points (<100 psi) removed.

Figure 24. WD40B pressure data with values less than 100 psi removed.
31

All of the data from Figures 21 and 23 were combined and are presented in Figure 25. A line was 

fit to the data (red line). The pressure dropped at a rate of R

-1.30, faster than the predictions of the 

UWCv1 (R

-1.13), but not as quickly as the predictions reported by UWCv2.

Figure 25. All of the 200-lb charge pressure data (with questionable values removed). 

Note the strong correspondence between the line fit to the data and the predictions of the UWCv1. The 

data values are much closer to the UWCv1 predictions for the 200-lb charges than the 75- and 100-lb 

charges.

3.2 ANALYSIS OF MEASUREMENT RESULTS

The individual pressure time series (waveforms) differed considerably in detailed form from the 

theoretical predictions for exponential decay of an explosive signal. This condition had been noted in 

earlier work (Poe et al., 2009). It has been suggested that multiple reflections from the structure, and 

from the water surface, may contribute to this effect.
32

3.2.1 Peak Pressure

The previous sections have presented the pressure results for each shot from each explosive event. 

Figures 26 and 27 present all of the data for each charge size. These figures showed that the measured 

decay rate with distance was a good match for both UWC predictions, although the amplitude was 

intermediate between the Version 1 and Version 2 (using TAR Project No. 570 input) predictions. 

Figure 26. All pressure data as a function of the log scaled-weight axis.

The UWC predictions are shown as well as a linear fit to the log-log plot. The curve fit to the data 

parallels the decay rate of the open-water curve (Figure 26), but at a reduced amplitude. 

Figure 27. Curve-fit decay rate plots for combined data.
33

A more general view can be obtained by combining data, where appropriate. Figure 28 shows the 

data for all charges, plotted as a function of the reduced-range (x-axis) of slant range/charge weight1/3.

The slope of the line fitted to those data was -0.8784, which indicates spreading rates intermediate 

between cylindrical and spherical. Figure 29 shows the same data, with the questionable data points 

removed. Here the measured decay rate of the data is -1.199, only slightly greater than the 1.13 value 

predicted by the UWCv1, albeit at a slighted reduced amplitude. The UWCv2 predictions show a 

greater rate of attenuation with range than that shown by the data. 

Figure 28. All pressure data as a function of the reduced range. Slope (red line) 

is -0.8784.
34

Figure 29. All pressure data as a function of the log scaled-weight axis, with the 

questionable data points removed. Slope (red line) is -1.199.

The measured values were compared with predictions from the UWCv2 for the well conductors and 

main piles, using the TAR 570, Connor, and open-water options (Dzwilewski, 2014). In both 

presentations of the pressure data, the curve fit to the data largely parallels that for the open-water 

predictions, albeit with what appears to be a near-constant offset with of the measured data having a 

lower amplitude. 
35

3.2.2 Impulse Data

Figures 30 and 31 show the impulse data plotted as a function of the reduced range, with and

without the suspect data points, respectively. As seen with the pressure data, the linear fit to impulse 

data has the same approximate slope (decay rate), as the predictions of the UWCv1. However, the 

amplitudes of the measured data are lower than the UWCv1 predictions.

Figure 30. Impulse data plotted as a function of the reduced range.

Figure 31. Impulse data plotted as a function of the reduced range, but 

with the questionable data points removed.
36

3.2.3 Energy Flux Density Data

The EFD data presented in Figures 32 and 33 show the same trend as seen in the pressure data, 

with the curve fit to the data paralleling that of the UWCv1 predictions.

Figure 32. Energy flux density (EFD) plotted as a function of the reduced-range

axis.

Figure 33. Energy flux density (EFD) plotted as a function of the reduced-range 

axis, but with the questionable data points removed.
37

4.0 DISCUSSION

There was considerable variability in the data, but clear trends were observed in comparisons of the 

measured data with the UWC (Versions 1 and 2) predictions. When measured data were compared 

with UWC predictions, the UWCv1 consistently overestimated the pressure levels and slightly 

underestimated decay rates for the 75- and 100-lb charges. However, the UWCv1 predictions showed a 

close fit for measured pressure levels and decay rates for all 200-lb charge data. The UWCv2 

predictions produced a poor fit to the measured pressure values. The UWCv2 (Connor and TAR 570) 

predicted a faster decay rate as compared to the UWCv1 and the measured results. 

Both forward and backward calculation Microsoft© Excel© spreadsheets are provided for UWCv1 

and UWCv2 in Appendix 1. The variation of predicted results for the EFD and decay rates between 

UWCv1 and UWCv2 to the measured values is most likely due to the premise upon which each 

calculator was built. The inputs to UWCv2 have been simplified compared to the inputs required for 

UWCv1. Specifically, UWCv1 requires the user to input pile diameter and thickness, while the 

UWCv2 requires the user to select a scenario, such as “main pile Connor” or “well conductor TAR

570”. These scenarios represent the type of structure being removed as well as the source of the 

measurement data (Connor or TAR 570). Despite these differences in inputs, the forward calculation in 

both versions still predicts the peak pressure, impulse, and energy flux density for an input slant range 

and explosive weight for a selected pile scenario, and these values provide the information necessary to 

calculate exclusion zones and take estimates.

The different required inputs stem from the premise upon which each calculator is built. The 

UWCv1 is based on near-field energy coupling from the physics of shock wave propagation 

(Dzwilewski and Fenton, 2003). These calculations use the physics of underwater propagation and the 

dampening effects of structural properties to theoretically calculate the near-field predictions. Those 

near-field predictions are also used in the far field. Conversely, the UWCv2 is based solely on 

curve-fits applied to the TAR 570 data and the Connor data (Dzwilewski, 2014). These curve-fit data 

are used for both the near-field and far-field calculations. The outputs from UWCv2 with either of 

these selected scenarios (Connor or TAR 570) will thus be driven specifically by the physical 

parameters of those individual project data sets and, therefore, may not be as universally applicable to 

all situations. This exact result is found when comparing the measured data from this study with the 

outputs of UWCv2. As such, the outputs of the two models (UWCv1 and UWCv2) differ markedly in 

their predicted attenuation rates (Dzwilewski, pers. comm.).

In some individual measurements, the recorded pressure value was higher at greater slant ranges 

(e.g., Figure 19, shot 1). This suggests a potential for error in individual measurements that must be 

considered during the interpretation of the data. Because most of the anomalous data points came from 

the near-bottom sensors, a number of factors may be at work in producing these results. The 

positioning of the sensor and interaction with the physical characteristics of the removal site likely have 

the greatest role in producing this anomaly. Each detonation is timed 1 to 2 s apart and will reach the 

array sensors along different pathways and, depending on the spatial relation to the sensors, will interact 

with other pressure waves (direct or reflected). Though individual variation is to be expected, the 

complexity of the pressure waves interacting with the substrate and the existing structure may create a

shadowing effect where pressure may be dampened before reaching certain sensors, producing results 

that appear as “higher” peak pressures and EFD in sensors that are farther away (Figure 34) from the 

detonation. This is best exemplified in the better slope-fit for peak pressure versus slant range (fixed)

between detonations that had no structure between the pile and the sensor (Figure 20, shot 4) compared 

to detonations that had piles, sonar reflectors, and other structures between the target pile and sensor

(Figure 20, shot 1). 

This is also seen in the relative consistency of good slope fit for all the near-surface sensors in the 

same figures. These assumptions hold true with and without the inclusion of sensors D and G, which 

likely show the complexity of interactions with the pressure waves for the lowest sensors. Specifically, 

there is less linear agreement between pressure measurements and slant range for piles that are 
38

detonated later in the sequence and for those that have other structures between them and the sensor 

array.

Figure 34. Sample detonation sequence (with sensors D and G removed) and pile location 

relative to sensor location.

Embedded graphs compare measured peak pressure (bar graph) to slant range (line graph). The 

bar graph color corresponds to the sensor location (surface, mid or bottom).

The water depths at the study sites were between 90 and 95 ft, almost twice as deep as the data 

collection efforts at the TAR 118 (Connor) and TAR 570 study sites. The difference in water depth 

may be related to the difference in the observed decay rates from the predictions that were based on the 

shallow water observations. The sediment type and characteristics were also different than at the 

previous study sites. Propagation of acoustic waves through a porous seabed depends on the type, 

distribution, density, and stress state of the sediments. The fundamental connection that exists between 

acoustic energy propagation and the physical and behavioral properties of the sediments is firmly 

established with the work of Hamilton and Bachman (1982), Bachman (1985), Richardson and Briggs 

(1993), and Wilkens (1998). Specifically, softer sediments will attenuate acoustic and pressure waves 

more effectively than harder sediments. However, the liquefied nature of the sediments found on the 

PWAP 40 sites may contribute to the inconsistency of the linear attenuation of the pressure wave.

It is not possible to quantify the specific contribution from suspended particles, water depth, 

structural interference, or other controlling factors, such as gas bubble entrapment. There is likely a 

synergistic effect among multiple factors that results in complex attenuation patterns in the near field. 
39

Although it is beyond the scope of the current project to evaluate these hypotheses, these variables seem 

relevant and worthy of further investigation and perhaps modification of UWCv2.

However, these outlier values affected only the pressure results shown in Figures 28 and 29. The 

curve fit to all of the data points has a decay rate less than that for the open water. When those points 

are removed, the decay rate is very close to that predicted by the UWCv1 for pile constrained

explosions (slopes of -1.19 and -1.13). The decay rates for impulse (Figures 30 and 31) and EFD 

(Figures 32 and 33) were not greatly affected by inclusion or removal of the suspect data points. This 

may result in part from the measurement process that removed any point for which a time constant 

could not be reliably measured.

The predictions of the two versions of the UWC differ markedly. UWCv2 predicts greater decay of 

amplitudes with range than UWCv1, which is based on numerical simulations of the shock wave 

propagation through the sediment. UWCv2 is based on empirical data from earlier experiments.

However, there were notable differences between those two earlier experiments and the current work, 

including water depth, pile diameter, charge size, and depth BML (Table 5).

Table 3. Comparison of parameters of past and current studies.

Experiment Water Depth (ft) Charge Sizes (lb) Depth BML (ft) Wall Thickness (in.)

TAR 118 (Connor) 53 25–50 8–26 1.00

TAR 570 50 75–145 15–30 0.625–1.50

Current 92 75–200 15–25 1.00–2.25
40

5.0 CONCLUSIONS

Compared to this study, earlier studies (Connor and TAR 570) that are used for UWCv2 

development took place in water that was about half as deep and used smaller charges that were often 

placed deeper than the current study BML level. UWCv1 is based on physics models, rather than 

curves fit to data from two specific locations that may vary greatly depending on project parameters. 

UWCv1 returned accurate predictions of the results from this study but overestimated the 

measurements from Connor and TAR 570 projects. But both the UWCv1 and UWCv2 predictions will 

produce safety ranges that are smaller than those for an open-water explosion.

The observed data from the current experiment were accurately predicted by UWCv1. As with the 

Connor and TAR 570 data, the UWCv1 generally over-predicted the actual measured PWAP levels. 

The UWCv2 was built on curves fit to the data from TAR 570 and the Connor experiments. The 

UWCv2 predictions had a quicker decay rate with range than the UWCv1 predictions and the observed 

data from the current study. These results suggest that the effects of the differing parameter

combinations are not fully incorporated into the UWCv2. The current study was conducted in deeper 

water and used larger charge sizes than either the Connor or TAR 570 project. 

All predicted and measured pressure level data for the BML detonations were lower than the 

predicted amplitudes of an open-water charge for all charge weights, indicating that using an openwater model calculation to establish take or safety zones would consistently overestimate the size of the 

impact area for detonations at any charge weight or depth BML. Conservative estimates from both 

UWCv1 and UWCv2 provide impact zone predictions that remain far below calculations for an openwater blast.

The implications for using either UWC to determine exclusion zones and impact assessment from 

decommissioning events lie in the utility of these calculators in predicting the impulse, EFD, and peak 

pressure at given distances from the platform. For impulse, EFD, and peak pressure, the measured 

attenuation was consistently better fit to the predicted values produced by the UWCv1 than by the 

UWCv2. Measured peak pressures were consistently lower than those predicted by UWCv1, but were 

variable compared to UWCv2; closer distances were over predicted and farther distances were under 

predicted. UWCv1 provides a consistently more conservative and accurate prediction of measured 

values important in impact evaluation. 

Regulatory use of the UWC involves the backward calculation that calculates the slant range for the 

input (e.g., Level B take criteria for pressure and energy flux density values for different open-water 

and pile scenarios). 

The objective of this study was to quantitatively measure the underwater pressure waves and 

acoustic proprieties generated by the detonation of explosives used for severance during offshore 

structure removal ops and provide BSEE and BOEM with scientifically valid data to update the ARA 

model so that the take harassment impact zones of protected species may be more accurately calculated. 

Data collection was needed to further document the dampening effects of the target structures and 

surrounding sediments; particularly by deepening the severance depth or making severance cuts internal 

to larger tubulars (i.e., cutting conductors in caissons or large jacket legs).

This study advanced the understanding of the underwater pressure waves and acoustic properties of 

severance-charge detonations under varying physical conditions. Charge weights were greater than for 

previous studies, water depth was greater than previous studies, and overall, wall thickness of the 

structures was generally larger than in previous studies. The dampening effects of sediment differences 

were also considered as a contributing factor in the resulting UWC calculations for this study when 

compared to previous studies. Charge depth within the structure and alternative methodologies of 

severance were not explored fully due to the operational parameters of the available target structures. 

The field measurements from this study and their predicted calculations using UWCv1 and UWCv2 

show that UWCv1 provides a more accurate and conservative prediction of impact criteria. Peak 

pressure (psi) and EFD are the dual criteria typically used by NMFS in determining impact zones and 

take estimates for marine mammals and sea turtles from explosive sources. Measured psi values during 
41

this study were generally lower than those predicted by the UWCv1 and were always lower than 

unconfined, open-water predictions for either UWCv1 or UWCv2. UWCv1 can be safely and 

conservatively used universally for impact assessment and survey planning, while UWCv2 could be 

used in some circumstances, namely for removals conducted near the TAR 570 or Connor study sites 

and with charge sizes that are no larger than 80 lb. UWCv2 is ideally the calculator version that should 

be applied in regulatory frameworks, because it uses project-specific information. However, based on 

this study, further refining of the UWCv2 is needed to achieve better agreement with EFD rates on a 

consistent basis. The data collected during this study can be applied for updating the UWCv2 model. 
42

6.0 LITERATURE CITED

Arons, A.B., D.R. Yennie, and T.P. Cotter. 1950. Long range shock propagation in underwater 

explosion phenomena II. In: Underwater Explosions: A Compendium of American and British 

Reports, Vol I, The Shock Wave. Office of Naval Research, Washington, DC.

U.S. Dept. of the Interior. Bureau of Safety and Environmental Enforcement. 2016. Offshore 

Statistics by Water Depth. Available at: 

www.data.bsee.gov/homepg/data_center/leasing/WaterDepth/WaterDepth.asp.

Bachman, Richard T. 1985. Acoustic and physical property relationships in marine sediment. The 

Journal of the Acoustical Society of America 78(2):616-621.

Connor, Jr., J. 1990. Underwater blast effects from explosive severance of offshore platform legs and 

well conductors. Naval Surface Warfare Center, Silver Spring, MD. NAVSWC TR 90-532. U.S. 

Dept. of the Interior, Minerals Management Service, Technology Assessment and Research (TAR) 

Program, Herndon, VA. [TAR Project No. 118]

Continental Shelf Associates, Inc. 2004. Explosive removal of offshore structures – information 

synthesis report. U.S. Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS 

Region, New Orleans, LA. OCS Study MMS 2003-070.

Department of the Navy. 1998. Final environmental impact statement: Shock Testing the Seawolf 

Submarine. U.S. Department of the Navy, Southern Division, Naval Facilities Engineering 

Command, North Charleston, SC.

Department of the Navy. 2001. Shock Trial of the Winston S. Churchill (DDG 81): Final 

environmental impact statement. Department of the Navy, Naval Sea Systems Command. 

Washington, D.C.

Dzwilewski, P. and G. Fenton. 2003. Shock Wave/Sound propagation modeling results for calculating 

marine protected species impact zones during explosive removal of offshore structures. Applied 

Research Associates, Inc., Kenner, LA, January 20, 2003.

Dzwilewski, P.T. 2014. Water Shock Prediction For Explosive Removal Of Offshore Structures: 

Underwater Calculator (UWC) Version 2.0 Update Based Upon Field Data.

Federal Register. 2008. Taking and importing marine mammals; taking marine mammals incidental to 

the explosive removal of offshore structures in the Gulf of Mexico. 73FR34875, pp. 34875-34894. 

Federal Register. 2014. Takes of marine mammals during specified activities; confined blasting 

operations by the US Army Corps of Engineers during the Port of Miami construction project in 

Miami, FL. 79 FR6545, pp. 6545-6567.

Frankel, A., and W. Ellison. 2004. Explosive removal model simulation report. U.S. Dept. of the 

Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS 

Study MMS 2004-064.

Hamilton, Edwin L., and R.T. Bachman. 1982. Sound velocity and related properties of marine 

sediments. The Journal of the Acoustical Society of America 72(6):1891-1904.
43

Kaiser, M.J., D.V. Mesyanzhinov, and A.G. Pulsipher. In preparation. Modeling structure removal 

processes in the Gulf of Mexico. U.S. Department of the Interior, Minerals Management Service, 

Gulf of Mexico OCS Region, New Orleans, LA.

Mathworks. 2014. Matlab. Cambridge, MA.

National Oceanic and Atmospheric Administration. 2006. Biological Opinion: Permitting Structure 

Removal Operations on the Gulf of Mexico Outer Continental Shelf. 133 pp.

Poe, W.T., C.F. Adams, R. Janda, and D. Kirklewsiki. 2009. Effect of Depth Below Mudline of Charge 

Placement During Explosive Removal of Offshore Structures (EROS) – final report. U.S. Dept. of 

the Interior, Minerals Management Service, Technology Assessment and Research (TAR) Program, 

Herndon, VA (TAR Project No. 570).

Richardson, M.D., and K.B. Briggs. 1993. On the use of acoustic impedance values to determine 

sediment properties. Final Report No. NRL/PP/7431-92-0001. Naval Research Lab, Stennis Space 

Center, MS. 12 pp.

Richardson, W.J., C.R. Greene, Jr., C.I. Malme, and D.H. Thomson. 1995. Marine Mammals and 

Noise. Academic Press, San Diego, CA. 576 pp.

Saint-Arnaud, D., P. Pelletier, W. Poe, and J. Fowler. 2004. Oil platform removal using engineered 

explosive charges: In-situ comparison of engineered and bulk explosive charges – final report. 

U.S. Dept. of the Interior, Minerals Management Service, Technology Assessment and Research

(TAR) Program, Herndon, VA. [TAR Project No. 429]

Swisdak, M.M., Jr. 1978. Explosion Effects and Properties: Part II - Explosion Effects in Water. 

Naval Surface Weapons Center, 22 February 1978.

Urick, R.J. 1983. Principles of Underwater Sound, 3rd edition. McGraw-Hill, New York. 423 pp.

U.S. Dept. of the Interior. Minerals Management Service. 2005. Structure-removal operations on the 

Outer Continental Shelf of the Gulf of Mexico—Programmatic environmental assessment. U.S. 

Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, 

LA. OCS EIS/EA MMS 2005-013. 333 pp. Available at: 

http://www.nmfs.noaa.gov/pr/pdfs/permits/mms2005_013.pdf Accessed February 8, 2016.

Wilkens, R.H., and M.D. Richardson. 1998. The influence of gas bubbles on sediment acoustic 

properties: in situ, laboratory, and theoretical results from Eckernförde Bay, Baltic Sea. 

Continental Shelf Research 18(14):1859-1892.
Appendix 1
45

WD40A Conductor Shot 1

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(psi)

Impulse 

(psi·s)

EFD 

(psi·in.)

Time 

Constant 

(s)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(psi)

Impulse

(psi-s)

EFD 

(psi-in.)

A 5 62.00 2.350 0.001 0.776 340.773 0.131 4.433 0.000 2.641 6.764 4.151 382.943 0.981 23.701

B 45 88.56 1.650 0.001 0.829 239.293 0.192 4.735 0.001 1.386 3.447 1.235 201.026 0.500 7.050

C 80 118.19 1.392 0.001 0.597 201.960 0.177 3.409 0.001 0.823 1.998 0.463 119.345 0.290 2.643

D 5 72.97 0.709 0.000 0.063 102.821 0.036 0.361 0.014 1.967 4.971 2.385 285.274 0.721 13.620

E 45 96.56 1.037 0.001 0.460 150.454 0.136 2.629 0.001 1.186 2.928 0.920 171.948 0.425 5.254

F 80 124.30 1.066 0.001 0.411 154.571 0.146 2.348 0.018 0.751 1.817 0.390 108.960 0.263 2.227

G 5 88.92 0.343 0.002 0.216 49.692 0.341 1.232 0.016 1.376 3.421 1.218 199.577 0.496 6.954

H 45 109.12 1.036 0.001 0.237 150.260 0.093 1.351 0.001 0.951 2.324 0.607 137.871 0.337 3.467

I 80 134.28 0.873 0.001 0.310 126.605 0.118 1.771 0.001 0.654 1.570 0.300 94.759 0.228 1.712

J 80 150.20 0.842 0.001 0.224 122.135 0.092 1.278 0.013 0.534 1.270 0.205 77.396 0.184 1.170

K 80 186.28

L 80 221.60 0.415 0.000 0.041 60.213 0.037 0.234 0.001 0.264 0.609 0.055 38.326 0.088 0.312
46

WD40A Conductor Shot 2

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse

(psi-s)

EFD 

(psi-in)

A 5 57.866 2.82864 0.1872 1.4234 410.259 0.1872 8.128 2.075 3.55741 10.167 8.0018 515.824 1.4746 45.692

B 45 85.723 1.63235 0.2362 1.1404 236.752 0.2362 6.512 2.805 1.74874 4.8374 2.1033 253.568 0.7016 12.01

C 80 116.08 1.09571 0.1822 0.6631 158.919 0.1822 3.7863 1.845 1.01123 2.7278 0.7504 146.629 0.3956 4.2852

D 5 71.701 1.07195 0.0062 0.0213 155.474 0.0062 0.1218 0.005 2.41491 6.78 3.8605 350.162 0.9834 22.044

E 45 95.609 1.41249 0.1601 0.6572 204.864 0.1601 3.7528 2.85 1.43574 3.9358 1.4513 208.183 0.5708 8.2869

F 80 123.56 1.04074 NaN NaN 150.946 NaN NaN NaN 0.90332 2.4241 0.6069 130.981 0.3516 3.4654

G 5 90.184 0.43666 0.0459 0.2313 63.3326 0.0459 1.3208 6.24 1.59557 4.3952 1.7701 231.358 0.6375 10.107

H 45 110.15 1.18377 0.1003 0.3624 171.691 0.1003 2.0691 1.445 1.11164 3.0117 0.8968 161.188 0.4368 5.1207

I 80 135.12 0.97099 0.1156 0.405 140.83 0.1156 2.3128 3.765 0.76844 2.0469 0.4477 111.424 0.2969 2.5563

J 80 152.48 0.90755 0.1039 0.2903 131.629 0.1039 1.6575 2.715 0.6177 1.6289 0.2968 89.566 0.2363 1.695

K 80 190.45 NaN NaN NaN NaN NaN NaN NaN 0.41329 1.07 0.1394 59.9272 0.1552 0.7958

L 80 226.89 0.47834 0.0437 0.0505 69.3769 0.0437 0.2886 1.78 0.30123 0.7686 0.0769 43.6778 0.1115 0.4389
47

WD40A Conductor Shot 3

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse

(psi-s)

EFD 

(psi-in)

A 5 51.824 2.35528 0.146 1.1048 341.605 0.146 6.3084 1.555 4.34188 12.523 11.642 629.573 1.8163 66.478

B 45 81.766 1.26149 0.1741 0.5304 182.964 0.1741 3.0285 4.26 1.90465 5.2894 2.4699 276.174 0.7672 14.104

C 80 113.18 0.89597 0.1389 0.2931 129.95 0.1389 1.6739 3.23 1.05839 2.861 0.8176 153.466 0.415 4.6688

D 5 62.927 0.50915 0.2108 0.1675 73.846 0.2108 0.9564 11.695 3.05732 8.6771 6.0172 443.312 1.2585 34.359

E 45 89.218 0.96449 0.0048 0.0099 139.888 0.0048 0.0566 0.005 1.62695 4.4856 1.8361 235.907 0.6506 10.485

F 80 118.68 0.80214 0.1071 0.203 116.34 0.1071 1.1593 3.14 0.9715 2.6158 0.6959 140.867 0.3794 3.9738

G 5 79.861 0.22902 0.0332 0.0193 33.2164 0.0332 0.1102 1.9 1.98754 5.5304 2.6761 288.194 0.8021 15.281

H 45 101.87 0.78365 0.0581 0.1702 113.658 0.0581 0.972 2.775 1.28022 3.491 1.1697 185.632 0.5063 6.6789

I 80 128.46 0.57066 0.056 0.1744 82.7677 0.056 0.9961 5.34 0.84193 2.2521 0.5316 122.079 0.3266 3.0355

J 80 144.37 0.5636 0.0675 0.1179 81.7426 0.0675 0.6731 1.61 0.68184 1.8063 0.3575 98.867 0.262 2.0413

K 80 180.84 NaN NaN NaN NaN NaN NaN NaN 0.45385 1.18 0.1662 65.8076 0.1711 0.949

L 80 216.64 0.34974 0.0226 0.0247 50.725 0.0226 0.1409 2.475 0.32745 0.8387 0.0899 47.48 0.1216 0.5135
48

WD40A Conductor Shot 4

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi-s)

EFD 

(psi-in)

A 5 46.836 3.84132 0.245 2.4137 557.137 0.245 13.782 2.035 5.21314 15.163 16.424 755.906 2.1992 93.781

B 45 78.699 2.37114 0.2754 1.7271 343.905 0.2754 9.8619 3.695 2.04087 5.6857 2.8128 295.927 0.8246 16.061

C 80 110.99 1.72346 0.0803 0.4553 249.967 0.0803 2.6 0.005 1.09652 2.9689 0.8739 158.995 0.4306 4.9903

D 5 61.196 0.56509 0.0764 0.0933 81.9591 0.0764 0.533 3.615 3.21535 9.1467 6.6157 466.225 1.3266 37.777

E 45 88.005 2.26389 0.1739 1.0918 328.35 0.1739 6.2345 2.675 1.66766 4.6031 1.9236 241.811 0.6676 10.984

F 80 117.77 1.5736 0.1775 0.7197 228.231 0.1775 4.1098 3.06 0.98508 2.6541 0.7143 142.837 0.3849 4.079

G 5 80.904 0.57102 0.0873 0.3278 82.8196 0.0873 1.8719 6.01 1.9415 5.3965 2.5606 281.517 0.7827 14.621

H 45 102.69 2.14673 0.1095 0.6588 311.356 0.1095 3.7619 1.715 1.26182 3.4386 1.1382 182.964 0.4987 6.4994

I 80 129.11 1.48946 0.0139 0.0711 216.028 0.0139 0.4061 0.005 0.83427 2.2307 0.5225 120.97 0.3235 2.9838

J 80 146.43 1.39076 0.1096 0.4728 201.712 0.1096 2.6997 2.495 0.66457 1.7585 0.3406 96.363 0.255 1.9451

K 80 184.77 NaN NaN NaN NaN NaN NaN NaN 0.43656 1.133 0.1545 63.3008 0.1643 0.8822

L 80 221.67 0.95276 0.0409 0.1026 138.186 0.0409 0.5857 1.39 0.31416 0.8031 0.0832 45.5532 0.1165 0.475
49

WD40A Conductor Shot 5

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi-s)

EFD 

(psi-in)

A 5 41.217 3.82985 0.176 1.6128 555.472 0.176 9.2094 1.115 6.56741 19.305 25.362 952.275 2.8 144.82

B 45 75.491 2.0324 0.2046 0.9814 294.775 0.2046 5.6036 3.38 2.20031 6.1511 3.2404 319.045 0.8921 18.503

C 80 108.74 1.86328 0.1509 0.6877 270.246 0.1509 3.9268 1.85 1.13789 3.0861 0.937 164.994 0.4476 5.3505

D 5 52.265 0.39385 0.0412 0.0395 57.123 0.0412 0.2256 2.985 4.27586 12.324 11.311 619.999 1.7874 64.588

E 45 82.047 1.31136 0.1193 0.4951 190.197 0.1193 2.8273 3.335 1.8929 5.2553 2.4413 274.471 0.7622 13.94

F 80 113.39 1.25093 0.1264 0.4199 181.432 0.1264 2.3976 3.745 1.05497 2.8513 0.8127 152.97 0.4135 4.6405

G 5 70.413 0.34933 NaN NaN 50.6661 NaN NaN NaN 2.4953 7.0162 4.1059 361.819 1.0176 23.445

H 45 94.647 0.9541 0.0673 0.2843 138.381 0.0673 1.6231 2.395 1.46222 4.0117 1.502 212.022 0.5819 8.5767

I 80 122.81 1.12641 0.102 0.3204 163.373 0.102 1.8294 3.345 0.91321 2.4519 0.6194 132.416 0.3556 3.5371

J 80 138.57 0.94114 0.0772 0.2201 136.501 0.0772 1.2569 2.595 0.73425 1.9517 0.4109 106.466 0.2831 2.3465

K 80 175.32 NaN NaN NaN NaN NaN NaN NaN 0.47999 1.2512 0.1847 69.598 0.1815 1.0545

L 80 211.57 0.56053 0.029 0.0497 81.2978 0.029 0.2836 1.81 0.34177 0.8771 0.0975 49.5571 0.1272 0.5566
50

WD40A Conductor Shot 6

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse

(psi-s)

EFD 

(psi-in)

A 5 56.822 0.65409 0.0359 0.0671 94.8672 0.0359 0.3833 1.255 3.09155 7.976 5.5827 448.275 1.1568 31.878

B 45 85.022 0.4643 0.0652 0.0745 67.3409 0.0652 0.4253 1.585 1.49253 3.724 1.4184 216.416 0.5401 8.0991

C 80 115.56 0.81322 -0.003 0.0163 117.948 -0.003 0.0933 0.175 0.85724 2.0851 0.4997 124.3 0.3024 2.8531

D 5 67.868 0.32535 0.0071 0.0067 47.1886 0.0071 0.0383 0.08 2.24264 5.7012 3.0516 325.183 0.8269 17.425

E 45 92.769 0.54259 0.0452 0.0569 78.6967 0.0452 0.3251 2.835 1.27492 3.1581 1.0544 184.864 0.458 6.021

F 80 121.37 0.30109 NaN NaN 43.6688 NaN NaN NaN 0.78448 1.9003 0.4229 113.75 0.2756 2.4146

G 5 84.299 0.22108 0.0108 0.0052 32.0649 0.0108 0.0294 0.99 1.51574 3.7845 1.4602 219.782 0.5489 8.3378

H 45 105.39 0.45104 0.0327 0.0382 65.4177 0.0327 0.2181 1.815 1.01254 2.4817 0.6835 146.818 0.3599 3.9028

I 80 131.27 0.38312 0.0394 0.0314 55.5666 0.0394 0.179 3.315 0.68088 1.6387 0.3239 98.7274 0.2377 1.8497

J 80 147.19 0.29859 0.0286 0.0288 43.3073 0.0286 0.1646 3.44 0.55365 1.3199 0.2195 80.279 0.1914 1.2533

K 80 183.48 NaN NaN NaN NaN NaN NaN NaN 0.37177 0.8702 0.1037 53.9066 0.1262 0.5924

L 80 219.06 0.2586 0.0142 0.0098 37.5065 0.0142 0.056 1.455 0.2699 0.6225 0.0568 39.135 0.0903 0.3243
51

WD40A Conductor Shot 7

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi-s)

EFD 

(psi-in)

A 5 48.016 4.36631 0.1864 2.9816 633.28 0.1864 17.025 1.425 4.98391 14.466 15.091 722.667 2.0981 86.172

B 45 74.199 2.41494 0.0509 0.3984 350.258 0.0509 2.2748 0.005 2.26999 6.355 3.4362 329.148 0.9217 19.621

C 80 104.55 1.13851 0.1251 0.3521 165.127 0.1251 2.0104 2.145 1.22159 3.324 1.0709 177.13 0.4821 6.1149

D 5 63.204 1.31968 0.0576 0.2249 191.403 0.0576 1.2845 1.245 3.03314 8.6053 5.928 439.806 1.2481 33.85

E 45 84.822 2.0312 0.0207 0.1313 294.6 0.0207 0.7496 0.005 1.78248 4.9351 2.1803 258.46 0.7158 12.45

F 80 112.34 2.14055 0.1205 0.4196 310.461 0.1205 2.396 1.835 1.07285 2.9019 0.8388 155.563 0.4209 4.7896

G 5 83.095 1.03333 0.0467 0.1167 149.872 0.0467 0.6665 1.39 1.84999 5.1307 2.3382 268.248 0.7442 13.352

H 45 100.52 2.1257 0.1052 0.6467 308.306 0.1052 3.6927 1.785 1.31144 3.5801 1.2239 190.159 0.5193 6.9886

I 80 124.62 2.14673 0.1141 0.4264 311.356 0.1141 2.4347 1.745 0.88945 2.3852 0.5895 128.97 0.3459 3.3659

J 80 142.92 1.2963 0.0902 0.39 188.012 0.0902 2.2268 2.06 0.69433 1.8409 0.3699 100.678 0.267 2.1122

K 80 182.51 NaN NaN NaN NaN NaN NaN NaN 0.44636 1.1597 0.1611 64.7223 0.1682 0.9198

L 80 220.06 0.88315 0.0387 0.1282 128.09 0.0387 0.7321 1.925 0.31832 0.8143 0.0853 46.1568 0.1181 0.4869
52

WD40A Conductor Shot 8

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse

(psi-s)

EFD 

(psi-in)

A 5 36.313 5.48228 0.2694 4.3639 795.137 0.2694 24.918 1.285 6.94296 18.591 25.584 1006.73 2.6963 146.09

B 45 67.221 3.60635 0.2553 1.9522 523.057 0.2553 11.148 2.52 2.28182 5.8054 3.1527 330.864 0.842 18.002

C 80 99.718 2.37975 0.1851 1.0205 345.153 0.1851 5.8274 1.885 1.11892 2.7551 0.8248 162.244 0.3996 4.7099

D 5 52.599 1.17698 0.0306 0.123 170.707 0.0306 0.7025 0.005 3.55451 9.2294 7.259 515.404 1.3386 41.45

E 45 77.244 2.18343 0.1744 1.1616 316.679 0.1744 6.6327 2.33 1.77505 4.4643 1.9654 257.383 0.6475 11.223

F 80 106.73 1.76334 0.1609 0.7142 255.751 0.1609 4.0781 2.625 0.98959 2.4229 0.6546 143.491 0.3514 3.738

G 5 74.061 0.72736 0.0608 0.1244 105.495 0.0608 0.7101 2.25 1.91531 4.8339 2.2678 277.72 0.7011 12.949

H 45 93.193 1.68462 0.1022 0.7827 244.333 0.1022 4.4693 2.77 1.26446 3.131 1.0382 183.347 0.4541 5.9284

I 80 118.79 1.88405 0.142 0.6518 273.258 0.142 3.7217 2.62 0.81562 1.9793 0.455 118.264 0.2871 2.598

J 80 137.07 1.56101 0.1155 0.518 226.406 0.1155 2.958 2.22 0.62973 1.5102 0.2797 91.3108 0.219 1.5969

K 80 177.05 NaN NaN NaN NaN NaN NaN NaN 0.39655 0.931 0.1171 57.4992 0.135 0.6689

L 80 215.07 1.03998 0.0456 0.1845 150.837 0.0456 1.0534 1.875 0.27901 0.6445 0.0605 40.4567 0.0935 0.3452
53

WD40A Pile Shot 1

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi-s)

EFD 

(psi-in)

A 5 121.06 0.65982 0.3443 0.3889 95.6994 0.3443 2.2206 10.995 0.38416 0.6581 0.0905 55.7034 0.0955 0.5166

B 45 135.11 1.72287 0.2685 0.8864 249.881 0.2685 5.0615 4.08 0.33163 0.5607 0.0645 48.0856 0.0813 0.3682

C 80 155.02 3.24148 0.1919 0.98 470.136 0.1919 5.5957 1.845 0.27589 0.4589 0.0422 40.0035 0.0666 0.2411

D 5 142.21 0.4281 0.138 0.3257 62.0902 0.138 1.8599 15.4 0.30966 0.5204 0.0551 44.9 0.0755 0.3145

E 45 154.35 1.34833 0.2083 0.5532 195.559 0.2083 3.1588 4.185 0.27749 0.4618 0.0428 40.2357 0.067 0.2443

F 80 172.04 1.9741 0.1596 0.6719 286.319 0.1596 3.8367 2.36 0.23996 0.3942 0.0306 34.7938 0.0572 0.1749

G 5 163.26 0.26505 0.1511 0.4192 38.4425 0.1511 2.3938 47.515 0.25739 0.4255 0.036 37.3215 0.0617 0.2055

H 45 173.94 1.16883 0.1361 0.3335 169.524 0.1361 1.9041 3.195 0.23646 0.388 0.0296 34.2866 0.0563 0.1691

I 80 189.82 2.42948 0.1407 0.5903 352.366 0.1407 3.3709 1.875 0.21036 0.3416 0.0226 30.5022 0.0495 0.1292

J 80 206.08 1.86851 0.137 0.4791 271.004 0.137 2.7356 2.315 0.18844 0.303 0.0176 27.3233 0.0439 0.1003

K 80 245.27 1.24685 0.0812 0.265 180.84 0.0812 1.5131 1.865 0.14925 0.2351 0.0103 21.6413 0.0341 0.0586

L 80 288.32 0.97512 0.0449 0.1657 141.43 0.0449 0.946 2.04 0.12019 0.1857 0.0062 17.4279 0.0269 0.0356
54

WD40A Pile Shot 2

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse

(psi-s)

EFD 

(psi-in)

A 5 89.527 3.65485 0.0679 0.7664 530.091 0.0679 4.3763 0.005 0.57541 1.0218 0.2293 83.4349 0.1482 1.3092

B 45 107.77 4.65467 0.2847 3.2238 675.103 0.2847 18.408 2.075 0.44886 0.7797 0.1294 65.0852 0.1131 0.7391

C 80 131.87 4.54263 0.27 1.9761 658.853 0.27 11.284 1.89 0.34258 0.5809 0.0695 49.6745 0.0843 0.3968

D 5 100.55 1.21294 0.0717 0.1809 175.922 0.0717 1.0332 1.575 0.49255 0.8626 0.1603 71.419 0.1251 0.9153

E 45 117.09 4.36305 0.241 2.193 632.807 0.241 12.522 1.685 0.40169 0.6909 0.1002 58.2444 0.1002 0.5724

F 80 139.59 4.23225 0.2231 1.6395 613.836 0.2231 9.362 1.825 0.31746 0.5347 0.0583 46.0311 0.0776 0.333

G 5 115.39 0.9173 0.4684 0.7688 133.043 0.4684 4.3899 13.205 0.40964 0.7058 0.1049 59.3981 0.1024 0.5989

H 45 130.06 3.59614 0.1814 1.314 521.576 0.1814 7.5029 1.68 0.349 0.5928 0.0725 50.6046 0.086 0.4142

I 80 150.63 4.07666 0.1871 1.507 591.269 0.1871 8.6054 1.685 0.28669 0.4785 0.0461 41.5707 0.0694 0.2634

J 80 162.01 4.16538 0.1693 1.2767 604.138 0.1693 7.29 1.4 0.26006 0.4303 0.0369 37.7085 0.0624 0.2104

K 80 194.39 2.46485 0.118 0.7352 357.497 0.118 4.1981 1.78 0.20375 0.3299 0.021 29.5441 0.0479 0.12

L 80 234.12 2.28405 0.0825 0.4918 331.274 0.0825 2.808 1.44 0.15884 0.2516 0.0118 23.0319 0.0365 0.0677
55

WD40A Pile Shot 3

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi-s)

EFD 

(psi-in)

A 5 51.836 7.99821 0.4571 10.014 1160.04 0.4571 57.181 1.315 1.19607 2.2667 1.2353 173.43 0.3288 7.0539

B 45 79.291 6.3425 0.457 6.3841 919.902 0.457 36.454 1.705 0.677 1.2197 0.3333 98.1657 0.1769 1.9034

C 80 109.83 4.75378 0.0625 0.6679 689.478 0.0625 3.8138 0.205 0.43766 0.7585 0.1221 63.461 0.11 0.6974

D 5 67.735 1.74664 0.9892 3.4524 253.328 0.9892 19.714 14.105 0.83597 1.5346 0.5417 121.216 0.2226 3.0929

E 45 90.487 5.43682 0.3541 4.4467 788.544 0.3541 25.391 2.27 0.56725 1.006 0.2219 82.2517 0.1459 1.2668

F 80 118.17 4.99916 0.3037 2.5925 725.068 0.3037 14.804 2.02 0.39681 0.6818 0.0975 57.5379 0.0989 0.5566

G 5 87.331 1.12372 0.7131 1.7424 162.982 0.7131 9.9493 23.04 0.59487 1.0595 0.2475 86.256 0.1537 1.4133

H 45 105.96 3.64595 0.2463 2.2279 528.8 0.2463 12.722 2.37 0.4592 0.7993 0.1364 66.5842 0.1159 0.7789

I 80 130.39 3.84151 0.2564 2.1406 557.164 0.2564 12.223 2.34 0.3478 0.5906 0.072 50.4314 0.0857 0.4109

J 80 143.45 3.04336 0.2204 1.6383 441.402 0.2204 9.3549 2.59 0.30607 0.5139 0.0536 44.3796 0.0745 0.3062

K 80 178.46 2.34064 0.1238 0.6458 339.481 0.1238 3.6875 0.955 0.22848 0.3738 0.0274 33.1298 0.0542 0.1562

L 80 218.91 1.36596 0.0862 0.2725 198.115 0.0862 1.5563 2.43 0.1738 0.2775 0.0146 25.2007 0.0402 0.0832
56

WD40A Pile Shot 4

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse

(psi-s)

EFD 

(psi-in)

A 5 31.166 12.8522 0.6659 20.164 1864.06 0.6659 115.14 1.62 2.36382 4.7592 5.926 342.754 0.6903 33.839

B 45 67.611 7.56311 0.5633 8.3496 1096.94 0.5633 47.678 2.37 0.83802 1.5387 0.5447 121.512 0.2232 3.1103

C 80 101.72 4.31436 0.4222 3.5914 625.745 0.4222 20.507 3.235 0.48501 0.8483 0.1547 70.3264 0.123 0.8834

D 5 51.747 2.189 1.2137 6.4459 317.488 1.2137 36.807 19.89 1.19884 2.2724 1.2419 173.832 0.3296 7.0916

E 45 79.232 6.41817 0.3265 5.5725 930.876 0.3265 31.82 1.82 0.67768 1.221 0.3341 98.2629 0.1771 1.9077

F 80 109.78 4.99632 0.3009 2.932 724.656 0.3009 16.742 2.15 0.43789 0.7589 0.1223 63.4938 0.1101 0.6982

G 5 74.506 3.15863 0.3186 1.9729 458.121 0.3186 11.266 1.105 0.73584 1.3356 0.4038 106.697 0.1937 2.3059

H 45 95.662 4.00124 0.2205 1.6514 580.331 0.2205 9.4299 1.85 0.52655 0.9277 0.1869 76.35 0.1346 1.0673

I 80 122.17 4.43569 0.2321 2.4064 643.342 0.2321 13.741 1.88 0.37948 0.6494 0.0879 55.0249 0.0942 0.5022

J 80 136.1 4.28482 0.1823 1.6698 621.46 0.1823 9.5348 1.525 0.32842 0.5548 0.0631 47.6203 0.0805 0.3601

K 80 171.8 1.98389 0.0062 0.0286 287.739 0.0062 0.1632 0.005 0.2404 0.395 0.0308 34.8586 0.0573 0.1756

L 80 211.28 0.98575 0.0815 0.1972 142.971 0.0815 1.1259 3.12 0.18225 0.2922 0.0163 26.4264 0.0424 0.0928
57

WD40A Pile Shot 5

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse

(psi-s)

EFD 

(psi-in)

A 5 87.244 0.75163 0.2316 0.3324 109.014 0.2316 1.8982 6.315 0.59567 1.061 0.2483 86.3716 0.1539 1.4177

B 45 105.88 1.16805 0.1984 0.5745 169.411 0.1984 3.2802 5.125 0.45962 0.8 0.1367 66.6448 0.116 0.7805

C 80 130.33 2.55666 0.2517 1.5022 370.812 0.2517 8.5776 3.23 0.34801 0.591 0.0721 50.4617 0.0857 0.4115

D 5 113.09 0.48518 0.0374 0.0423 70.3689 0.0374 0.2418 1.415 0.42081 0.7268 0.1116 61.0179 0.1054 0.6371

E 45 128.03 1.01397 0.0314 0.1116 147.063 0.0314 0.6373 0.005 0.35644 0.6066 0.0761 51.6831 0.088 0.4348

F 80 148.88 3.06483 0.1661 0.8449 444.516 0.1661 4.8248 1.675 0.29122 0.4868 0.0478 42.2267 0.0706 0.273

G 5 137.44 0.36277 0.2284 0.3797 52.6148 0.2284 2.168 29.285 0.32411 0.5469 0.0612 46.9962 0.0793 0.3493

H 45 149.97 0.78918 0.1158 0.2573 114.461 0.1158 1.4691 4.05 0.28839 0.4816 0.0468 41.8163 0.0699 0.267

I 80 168.13 1.58065 0.1542 0.4167 229.254 0.1542 2.3792 3.08 0.24747 0.4077 0.0329 35.8835 0.0591 0.1877

J 80 186.39 1.46885 0.1187 0.3483 213.039 0.1187 1.9891 3.045 0.21555 0.3508 0.0239 31.2542 0.0509 0.1366

K 80 227.78 0.82593 0.0573 0.182 119.792 0.0573 1.0391 3.105 0.16479 0.2619 0.0129 23.8945 0.038 0.0736

L 80 270.1 0.68046 0.0352 0.1012 98.6927 0.0352 0.5779 2.455 0.13117 0.2043 0.0076 19.02 0.0296 0.0435
58

WD40A Pile Shot 6

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi-s)

EFD 

(psi-in)

A 5 96.578 1.05572 0.0616 0.1784 153.119 0.0616 1.019 1.32 0.51988 0.9149 0.1815 75.382 0.1327 1.0364

B 45 113.7 1.15053 0.0439 0.1185 166.87 0.0439 0.6764 0.99 0.41783 0.7212 0.1098 60.5849 0.1046 0.6268

C 80 136.76 3.23006 0.0955 0.8104 468.481 0.0955 4.6276 0.975 0.3263 0.5509 0.0621 47.3134 0.0799 0.3548

D 5 121.25 0.47091 0.0219 0.0302 68.2992 0.0219 0.1725 0.795 0.38337 0.6566 0.09 55.5884 0.0952 0.5141

E 45 135.28 1.08465 0.0133 0.046 157.315 0.0133 0.2626 0.005 0.33108 0.5597 0.0642 48.0059 0.0812 0.3668

F 80 155.16 2.35756 0.0538 0.2053 341.935 0.0538 1.1721 0.69 0.27554 0.4583 0.0421 39.953 0.0665 0.2404

G 5 144.8 0.48491 0.0169 0.0248 70.3302 0.0169 0.1413 0.835 0.30226 0.5069 0.0521 43.8281 0.0735 0.2975

H 45 156.74 0.78918 0.0311 0.1104 114.461 0.0311 0.6306 0.725 0.27184 0.4516 0.0408 39.4166 0.0655 0.233

I 80 174.19 1.45333 0.033 0.1522 210.787 0.033 0.8692 0.925 0.23601 0.3872 0.0295 34.2209 0.0562 0.1683

J 80 191.83 2.16366 0.0276 0.1198 313.812 0.0276 0.6842 0.415 0.20741 0.3364 0.0219 30.074 0.0488 0.125

K 80 232.84 0.8171 0.0206 0.0456 118.511 0.0206 0.2604 0.705 0.16001 0.2536 0.0121 23.202 0.0368 0.0688

L 80 276.11 0.47079 0.0154 0.0288 68.2821 0.0154 0.1644 0.8 0.12737 0.1978 0.0071 18.4679 0.0287 0.0407
59

WD40B Pile Shot 1

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi-s)

EFD 

(psi-in)

A 5 32.947 12.7547 0.9924 29.988 1849.91 0.9924 171.24 2.61 2.19426 4.3887 4.993 318.168 0.6365 28.511

B 45 68.451 6.6754 0.5505 6.8687 968.185 0.5505 39.221 2.645 0.82428 1.5113 0.5244 119.521 0.2192 2.9943

C 80 102.28 4.35145 0.3493 2.8065 631.125 0.3493 16.025 1.865 0.48146 0.8415 0.1521 69.8113 0.1221 0.8686

D 5 53.467 3.29349 0.1449 1.6575 477.681 0.1449 9.4644 0.005 1.14747 2.1666 1.1228 166.383 0.3142 6.4116

E 45 80.366 4.76048 0.3199 2.7817 690.449 0.3199 15.884 2.235 0.6649 1.196 0.3198 96.4104 0.1735 1.826

F 80 110.61 4.31178 0.2978 2.2472 625.371 0.2978 12.832 2.295 0.43354 0.7507 0.1195 62.8632 0.1089 0.6823

G 5 75.245 2.61631 0.4068 2.3088 379.464 0.4068 13.183 3.52 0.72618 1.3165 0.3917 105.296 0.1909 2.2367

H 45 96.239 3.37477 0.1874 1.4824 489.469 0.1874 8.4646 0.47 0.52233 0.9196 0.1835 75.7377 0.1334 1.0477

I 80 122.62 4.0583 0.2444 1.6963 588.607 0.2444 9.6859 1.985 0.37761 0.6459 0.087 54.7533 0.0937 0.4965

J 80 139.21 3.18978 0.2267 1.3172 462.639 0.2267 7.5212 2.43 0.31861 0.5368 0.0588 46.1979 0.0779 0.3358

K 80 170.06 1.91796 0.1893 0.6678 278.176 0.1893 3.8131 3.245 0.24372 0.401 0.0317 35.3387 0.0582 0.1812

L 80 213.72 1.48393 0.1643 0.4563 215.226 0.1643 2.6056 3.53 0.17947 0.2874 0.0157 26.0233 0.0417 0.0896
60

WD40B Pile Shot 2

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

Above 

Mudline 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSIpsi)

Impulse

(psi-s)

EFD 

(psi-in)

A 5 59.709 8.0728 0.5578 11.899 1170.86 0.5578 67.943 2.255 0.98976 1.8444 0.799 143.516 0.2675 4.5622

B 45 84.647 5.54531 0.3209 4.5912 804.279 0.3209 26.216 2.17 0.62026 1.1088 0.2725 89.938 0.1608 1.5561

C 80 113.75 3.87779 0.2493 2.3986 562.426 0.2493 13.697 2.08 0.41755 0.7206 0.1096 60.5443 0.1045 0.6258

D 5 77.623 5.27415 0.2744 3.3224 764.951 0.2744 18.971 1.65 0.69655 1.2581 0.3559 101 0.1825 2.0323

E 45 98.109 4.14938 0.2357 2.8986 601.817 0.2357 16.552 2.39 0.50904 0.8942 0.1729 73.8111 0.1297 0.9874

F 80 124.1 3.57781 0.2153 1.899 518.918 0.2153 10.843 2.305 0.37162 0.6348 0.0838 53.8848 0.0921 0.4786

G 5 97.11 4.80024 0.2607 3.8876 696.216 0.2607 22.199 1.615 0.51606 0.9076 0.1785 74.8287 0.1316 1.019

H 45 114.15 3.64595 0.2314 2.2307 528.8 0.2314 12.737 2.495 0.41561 0.717 0.1084 60.2632 0.104 0.6191

I 80 137.13 3.34139 0.2057 1.6626 484.628 0.2057 9.4935 2.425 0.3251 0.5487 0.0616 47.1395 0.0796 0.3518

J 80 154.64 2.71376 0.211 1.5291 393.597 0.211 8.7312 2.61 0.27678 0.4605 0.0425 40.1329 0.0668 0.2429

K 80 186.03 2.14755 0.1756 0.9894 311.475 0.1756 5.6495 2.745 0.21611 0.3518 0.0241 31.3355 0.051 0.1374

L 80 231.31 2.24547 0.1503 0.7097 325.678 0.1503 4.0525 2.4 0.16143 0.2561 0.0123 23.4078 0.0371 0.0702
61

WD40B Pile Shot3

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSI)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSI)

Impulse

(psi-s)

EFD 

(psi-in)

A 5 99.915 4.60442 0.1102 1.7857 667.815 0.1102 10.197 0.005 0.49675 0.8707 0.1635 72.0293 0.1263 0.9334

B 45 116.55 3.43698 0.0052 0.0744 498.492 0.0052 0.4247 0.005 0.40421 0.6956 0.1017 58.6104 0.1009 0.5807

C 80 139.13 3.27857 0.0058 0.0795 475.516 0.0058 0.4538 0.005 0.31886 0.5373 0.0589 46.2341 0.0779 0.3364

D 5 114.59 3.53665 0.1882 2.1755 512.948 0.1882 12.423 1.19 0.41349 0.713 0.1072 59.9564 0.1034 0.6119

E 45 129.35 2.93588 0.2223 1.5054 425.814 0.2223 8.5961 2.44 0.35157 0.5976 0.0738 50.9782 0.0867 0.4212

F 80 150.02 2.53708 0.181 1.1367 367.972 0.181 6.4905 2.525 0.28827 0.4814 0.0467 41.7989 0.0698 0.2667

G 5 130.91 3.06214 0.2221 2.2692 444.126 0.2221 12.957 2.26 0.34596 0.5872 0.0711 50.1641 0.0852 0.4059

H 45 144 2.34762 0.023 0.1739 340.493 0.023 0.993 0.005 0.3045 0.511 0.053 44.1522 0.0741 0.3026

I 80 162.83 2.87224 0.1986 1.0976 416.583 0.1986 6.2676 2.365 0.25832 0.4272 0.0363 37.4558 0.062 0.2072

J 80 179.96 2.60638 0.2042 1.0173 378.023 0.2042 5.8087 2.745 0.22592 0.3692 0.0267 32.7585 0.0535 0.1522

K 80 210.32 1.78491 0.1758 0.7308 258.88 0.1758 4.173 3.405 0.18336 0.2941 0.0165 26.5873 0.0427 0.0941

L 80 255.48 1.63099 0.1633 0.5611 236.554 0.1633 3.2039 3.275 0.14132 0.2215 0.0091 20.4908 0.0321 0.0517
62

WD40B Pile Shot4

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSI)

Impulse

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSI)

Impulse 

(psi-s)

EFD 

(psi-in)

A 5 132.49 1.85898 0.1792 1.0242 269.623 0.1792 5.8481 2.455 0.34046 0.577 0.0685 49.3666 0.0837 0.3912

B 45 145.44 1.43962 0.0582 0.4008 208.799 0.0582 2.2885 1.49 0.30048 0.5037 0.0514 43.5701 0.073 0.2935

C 80 164.1 1.52658 0.0426 0.1193 221.411 0.0426 0.6811 0.49 0.25564 0.4224 0.0354 37.0682 0.0613 0.2023

D 5 155.19 1.0788 0.0628 0.166 156.467 0.0628 0.9478 1.425 0.27547 0.4582 0.0421 39.9429 0.0665 0.2402

E 45 166.39 1.20589 0.0622 0.3454 174.899 0.0622 1.9725 1.3 0.25094 0.4139 0.0339 36.3862 0.06 0.1938

F 80 182.92 0.50901 0.1134 0.1463 73.8251 0.1134 0.8352 5.75 0.22104 0.3605 0.0254 32.0515 0.0523 0.1448

G 5 176.68 1.32648 0.0936 0.2754 192.389 0.0936 1.5723 1.545 0.23156 0.3792 0.0282 33.5765 0.055 0.1611

H 45 186.59 0.83235 0.1012 0.2378 120.722 0.1012 1.3577 2.905 0.21524 0.3502 0.0238 31.2104 0.0508 0.1362

I 80 201.47 1.61621 0.0472 0.1834 234.411 0.0472 1.0472 0.89 0.19423 0.3132 0.0188 28.1628 0.0454 0.1075

J 80 223.21 1.86277 0.0591 0.2069 270.171 0.0591 1.1816 1.065 0.16932 0.2697 0.0137 24.5516 0.0391 0.0784

K 80 258.8 0.70643 0.0847 0.1555 102.459 0.0847 0.888 3.485 0.1389 0.2174 0.0087 20.1404 0.0315 0.0497

L 80 307.13 0.73638 0.0738 0.1498 106.802 0.0738 0.8553 3.09 0.11044 0.1694 0.0051 16.0136 0.0246 0.0293
63

WD40B Pile Shot 5

Sensor and Charge Data Measured Data ARA UWCv2 Data

Sensor

Sensor 

Depth 

(ft)

Slant 

Range 

(ft)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSI)

Impulse 

(psi·s)

EFD 

(psi·in)

Time 

constant 

(sec)

Peak 

Pressure 

(Mpa)

Impulse 

(kPa·s)

EFD 

(kPa·m)

Peak 

Pressure 

(PSI)

Impulse

(psi-s)

EFD 

(psi-in)

A 5 105.52 3.03232 0.0506 0.4947 439.801 0.0506 2.8247 0.005 0.46175 0.8041 0.1382 66.9532 0.1166 0.7889

B 45 121.39 1.53598 0.1677 0.533 222.776 0.1677 3.0437 2.695 0.38278 0.6555 0.0897 55.503 0.0951 0.5123

C 80 143.21 0.20259 0.0551 0.0547 29.3835 0.0551 0.3123 9.89 0.30676 0.5151 0.0539 44.4799 0.0747 0.3078

D 5 130.31 0.55596 0.2154 0.2539 80.6345 0.2154 1.4497 11.925 0.3481 0.5911 0.0721 50.4747 0.0857 0.4117

E 45 143.46 1.33093 0.1364 0.508 193.036 0.1364 2.9007 3.32 0.30605 0.5138 0.0536 44.3778 0.0745 0.3061

F 80 162.34 0.56468 0.0737 0.1818 81.8997 0.0737 1.038 9.105 0.25935 0.4291 0.0366 37.6053 0.0622 0.2091

G 5 153.33 0.88676 0.1561 0.3081 128.614 0.1561 1.7596 5.275 0.27997 0.4663 0.0437 40.5955 0.0676 0.2494

H 45 164.65 1.36031 0.0142 0.0495 197.297 0.0142 0.2826 0.005 0.2545 0.4203 0.0351 36.902 0.061 0.2002

I 80 181.34 0.73756 0.1051 0.1806 106.974 0.1051 1.0311 3.35 0.22363 0.3651 0.026 32.4263 0.053 0.1487

J 80 203.35 1.14671 0.096 0.2135 166.317 0.096 1.2191 1.925 0.19182 0.309 0.0183 27.8145 0.0448 0.1044

K 80 239.47 1.04434 0.0733 0.1872 151.469 0.0733 1.0692 2.655 0.15411 0.2434 0.0111 22.3454 0.0353 0.0631

L 80 287.34 1.30222 0.0647 0.1376 188.871 0.0647 0.7856 1.6 0.12074 0.1866 0.0063 17.5077 0.0271 0.036

ARA = Advanced Research Associates Inc.; EFD = energy flux density; in. = inch; kPa = kilopascal; mPa = millipascal; psi = pounds per square inch; s = second; 

UWCv2 = underwater calculator version 2; WD40A = West Delta Block 40 platform A.
The Department of the Interior Mission

As the Nation’s principal conservation agency, the Department of the Interior has 

responsibility for most of our nationally owned public lands and natural 

resources. This includes fostering the sound use of our land and water 

resources; protecting our fish, wildlife, and biological diversity; preserving the 

environmental and cultural values of our national parks and historical places; 

and providing for the enjoyment of life through outdoor recreation. The 

Department assesses our energy and mineral resources and works to ensure 

that their development is in the best interests of all our people by encouraging 

stewardship and citizen participation in their care. The Department also has a 

major responsibility for American Indian reservation communities and for people 

who live in island communities.

The Bureau of Ocean Energy Management Mission

The Bureau of Ocean Energy Management (BOEM) works to manage the 

exploration and development of the nation's offshore resources in a way that 

appropriately balances economic development, energy independence, and 

environmental protection through oil and gas leases, renewable energy 

development and environmental reviews and studies.