600283112
EVALUATION OF A CONTAINMENT BARRIER
FOR HAZARDOUS MATERIAL-SPILLS IN WATERCOURSES
by
Thomas N. Blockwick
Samson Ocean Systems, Inc.
99 High Street
Boston, Massachusetts 02110
Contract No. 68-01-0103
and
Contract No. 68-03-2168
Project Officer
Ira Wilder
Oil and Hazardous Materials Spill Branch
Municipal Environmental Research Laboratory (Cincinnati)
U.S. Environmental Protection Agency
Edison, New Jersey 08837
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
-------
DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
-------
FORB-IORD
The U.S. Environmental Protection Agency was created because of in-
creasing public and government concern about the dangers of pollution to
the health and welfare of the American people. Noxious air, foul water,
and spoiled land are tragic testimonies to the deterioration of our natural
environment. The complexity of that environment and the interplay of its
components require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem
solution, and it involves defining the problem, measuring its impact, and
searching for solutions. The Municipal Environmental Research Laboratory
develops new and improved technology and systems to prevent, treat, and
manage wastewater and solid and hazardous waste pollutant discharges from
municipal and community sources, to preserve and treat public drinking
water supplies, and to minimize the adverse economic, social, health, and
aesthetic effects of pollution. This publication is one of the products of
that research and is a most vital communications link between the researcher
and the user community.
Development of methods, such as the Hazardous Material Barrier des-
cribed in this report, can help in the containment or confinement of spills
or leaks of hazardous materials in our waterways and prevent the dispersion
of potentially dangerous materials. Often, such confinement is the vital
first step before the manpower and equipment for cleanup and decontamination
can be brought to bear on an incident to protect the environment.
Francis T. Mayo
Director
Municipal Environmental
Research Laboratory
111
-------
PREFACE
Early in the Agency's history, growing concern over spills of hazardous
materials, particularly those which impact on our nation's waterways, led
the USEPA to recognize a need for quick containment of spills as a first
step in the clean-up process. The Hazardous Material Barrier (HMB) evolved
as one possible answer.
This study, conducted during the early 1970's, suggested that a
properly designed barrier system could contain spills and leaks that were
not rapidly dispersed into the water environment. This would include
releases of concentrated insoluble hazardous substances that pool on or
near the bottoms of watercourses. However, the studies also demonstrated
that the HMB had serious shortcomings, the greatest being its sensitivity
to currents, the time required for deployment, and weight-related handling
difficulties. Rapid technological advancements in plastics and their
fabrication, coupled with the experiences gained from this study, may make
it possible, today, to construct a barrier that can be deployed more
rapidly and with less difficulty.
Even though this report is being issued several years after project
completion, information on the study has been presented at the 1972
National Conference on Control of Hazardous Materials Spills and technical
advice has been provided on this topic to EPA Regions making inquires. It
is hoped that the release-of the report will stimulate those in the user
community that may want to further development of this concept.
iv
-------
ABSTRACT
Field tests were carried out during 1976 with an improved barrier for
the containment of hazardous material spills and leaks in waterways. The
improvements were based on the results of design, fabrication, and field
tests carried out in 1971 and 1972.
As currently configured, the Hazardous Material Barrier (HMB) consists
of a reinforced plastic film that can be used to encircle a spill or a
leaking vehicle, such as might result from a transportation accident. An
airfilled bladder provides flotation to keep the upper edge of the barrier
on the surface of the waterway while a liquid-filled bladder rests on the
bottom and seals the circumference, thus containing the spill in a minimum
volume of water and segregating it from the forces which tend to disperse
it.
While the current version of the HMB and its deployment still require
further improvements before the system could be considered practical for
field use, the trials reported at this time suggest that such a "curtain"
could be useful in containing a hazardous material spill or leak. The most
serious drawback of the HMB is its inability to retain its shape and, there-
fore, perform its function- when the current of the waterway exceeds 1 knot.
This report was submitted in fulfillment of Contracts No. 68-01-0103
and 68-03-2168 by Ocean Systems, Inc. under the sponsorship of the U.S.
Environmental Protection Agency and covers the period September 1971 to
July 1977. Work was completed as of July 1977.
-------
CONTENTS
Page
Foreword i i i
Preface i v
Abstract v
Fi gures vf 1
Tables viii
Acknowledgements ix
1. Introduction 1
2. Conclusions.... 2
3. Recommendations 4
4. Barrier System Development 6
5. Prototype Field Tests 12
6. Field Demonstration of the Modified Barrier 21
Appendix 39
Current Velocity Measurements
s,., vi
-------
FIGURES
Number Page
1 Vertohold embedment anchor 9
2 Pull-down schematic 10
3 Details of barrier construction ^ 17*
4 Palm Beach test site 22
5 Unloading the HMB from the van to the water ^ . 2£
6 Lacing air bladders together .. 26
7 HMB being towed*to test site 26
8 Diver releasing lines holding "D" rings 27
9 Pull-down grip being attached to mooring pendant 27
10 Underwater view of pull-down commencing..... 28
11 Winching down the HMB 28
12 HMB partially pulled down 29
13 Full pull-down at two adjacent anchors 29
14 Nearly inflated HMB on surface 30
15 Fully inflated HMB on surface 30
16 Fully inflated bottom seal rising above lagoon bottom 32
17 Fully collapsed HMB 32
18 Tears around "D" ring 36
v 19 Air test of HMB after repairs 36
20 Start of folding of HMB 37
21 Folding of HMB almost completed 37
22 HMB folded and tied 38
23 Current measurement stations 41
vn
-------
TABLES
Number Page
A-l In-situ Current Data for Station #1 42
A-2 In-situ Current Data for Station #2 43
A-3 Vertical Current Profiles for Station #1 44
A-4 Vertical Current Profiles for Station #2 45
-------
ACKNOWLEDGEMENTS
The assistance and advice provided by Mr. Ira Wilder and Dr. Joseph
Lafornara of EPA are gratefully acknowledged. The author also wishes to
express his appreciation to Mrs. Elaine Tomkins who assisted in the
preparation and arrangement of this document.
ix
-------
SECTION 1
INTRODUCTION
Despite a growing awareness of the dangers of hazardous materials,
accidental spills on land and into the nation's waterways still occur at an
alarming rate. Depending on the character of the spilled material and the
nature of the spill site, these incidents can present varying degrees of
hazard to the human and aquatic populations involved.
Although each incident requires specific counter-measures, certain
general requirements apply. For spills into waterways, counter-measures
must be effective in flowing streams, impoundments, estuaries, and the open
sea. They should be capable of rapid implementation in both congested and
remote areas. The counter-measure also should use a minimum of auxiliary
equipment, be safe to handle by semi-trained personnel, and should cause no
secondary damage to the environment.
A number of chemical, biological, and physical counter-measures for
dealing with spills are in use or have been tried with varying success. A
review of many of these methods indicated that physical containment of the
spill often is a vital first step in improving the potential for coping
with spills in waterways. Physical containment, by reducing dilution and
dispersion of the material, minimizes the volume of contaminated water that
must be treated and extends the time period over which the spill can be
treated. As a result, the ultimate treatment or disposal of the contained
substance often can be accomplished more safely and more effectively.
Based on these observations, it was proposed that a lightweight,
rapidly deployable, physical barrier system would be useful for a wide
variety of spilled substances. In June 1971, Ocean Systems, Inc. was
awarded a contract (68-01-0103) by the U.S. Environmental Protection Agency
(EPA) for the construction and testing of a prototype containment barrier
for hazardous material spills. Such a prototype containment system,
featuring a plastic film barrier, was designed, constructed, and tested
during 1971 and 1972.
Following the series of tests in 1971 and 1972, recommendations were
made for a new, strengthened Hazardous Material Barrier (HMB). This second
generation prototype was constructed and subsequently tested in June and
July of 1976, under a second contract, 68-03-2168. Results of both sets of
tests and recommendations for an operational version are presented herein.
-------
SECTION 2
CONCLUSIONS
As a result of the field tests conducted during the 1976 test program,
the following conclusions have been reached concerning the barrier system
for containment of hazardous material spills:
1. The barrier system can be a viable countermeasure against spilled
hazardous materials, although some changes are still required for
an optimized operational system.
2. Deployment of the Hazardous Material Barrier (HMB) can be
accomplished in time to contain slow spills or leaks or where a
significant amount of pollutant remains at the source 8 to 12 hr
after the barrier arrives at the scene.
3. Use of the barrier may not be feasible in all situations. The
On-Scene Coordinator must determine the feasibility of deploying
the system to combat an actual spill.
4. The barrier can be effective in average currents up to one knot '.
under good weather conditions.
5. Deployment of the barrier in currents faster than one knot is not
recommended. Retention of the desired circular shape cannot be
assured at higher currents; the barrier may lose its shape and
tend to close in on itself on the surface, while the lower seal
may tend to rise.
6. The self-embedment anchoring system used to moor the HMB is
extremely effective. Mushroom anchors (an option) present
problems.
7. Better deployment of the HMB can be achieved by using an improved
mechanical handling system, a trained crew and proper support,
including divers and suitable surface craft. Deployment of the
barrier by an untrained crew is difficult even under the best
conditions, but a marked improvement is achieved with a single
practice deployment.
8. The pull-down system for deployment works well, but a more
efficient system is needed to move the barrier into the water.
9. The field tests of the improved prototype have indicated specific
-------
areas where design changes would improve deployment of an
operational barrier.
10. Tidal flushing can be an important factor when using the barrier
and must oe considered when using the HMB.
-------
SECTION 3
RECOMMENDATIONS
We strongly recommend that the HMB system be made fully operational,
after incorporating the following changes in design and deployment
procedures: ^
1. Construct a new barrier with the following changes:
a. If feasible, use a zipper-type mechanism to attach the tvra
ends of the curtain. Retain the existing lacing and grommet
system as a backup.
b. Change the air bladder relief valve specifications to 1.0 or
1.5 psi over-pressure and use coarser threading on the valves.
Investigate the use of relief valves such as those on divers'
suits.
c. Use a non-kinking hose to insure that no kinking of air infla-
tion hoses can occur, particularly near the inlet to the air
bladder.
d. Insure more quality control over electronic welding of seams,
or use stitched seams.
e. Design a method and system for evacuation of the bottom seal
bladder and bleed-off of any trapped air. Investigate the
feasibility of using a zippered or double Velcro closure for
these purposes.
f. Use two inlets to fill the bottom seal bladder instead of
one; insure that no kinking of hoses can occur.
g. Use stronger or doubled material in the bottom seal bladder,
where most abrasion occurs.
h. Strengthen the barrier at other critical points as indicated
by the tests.
2. Design and construct a new handling and winch system to move the
barrier from land to water and back.
3. Implement changes in deployment techniques as follows:
-------
a. Use aivers v/hen possible. However, the use of divers should
not be designed into the system.
b. nsncve flotation before oull-down of iiruj', ^ction.
c. Inflate air bladder initially using a bank of conoressed air
tanks and top-off using a compressor.
d. If feasible, fill bottom seal bladder with a dense slurry
rather than water.
e. Use mechanical assistance and handling systems to maximum
advantage.
• \ -»•-
f. Minimize towing of the HMB in deployment and recovery
operations.
4. Develop mechanical aids to eliminate or reduce the need for
divers in deployment and recovery of the barrier.
5. Do not deploy the barrier in currents exceeding one knot.
"w
-------
SECTION 4
BARRIER SYSTEM DEVELOPMENT
DESIGN APPROACH
In accordance with the Environmental Protection Agency's general
objectives for the design of equipment for controlling spills of hazardous
materials (ref. FWQA Request for Proposal WA71-513), Ocean Systems, Inc.
used the following guidelines during development of the containment system
for use in watercourses. The system should:
Be effective in flowing streams, impoundments, estuaries, and in
moderate seas.
Be capable of rapid deployment in both congested and remote areas.
Be light in weight and easily transported.
Require a minimum of auxiliary equipment.
Be constructed of state-of-the-art materials and components and should
be reasonable in first cost.
Be capable of being deployed by a minimum number of trained
personnel.
Have a long shelf life with little or no maintenance.
Be ecologically acceptable and should not cause any secondary damage
to the environment.
To be effective against soluble substances, a containment barrier
should completely prevent escape of polluting materials from the contained
mass of water. This means that the bottom of the barrier must seal against
the bottom of the watercourse and that the top of the barrier must be sup-
ported above the water surface. A flexible fabric barrier with inflatable
support flotation and bottom seal was the only concept for a containment
barrier that was fully consistent with the guidelines presented above.
Because the barrier had to be designed for use in flowing v/ater, an
anchoring scheme that provides strong vertical holding power for restraining
the barrier and holding it tightly to the bottom of the v/atercourse was
required. Explosive embedment anchors were considered to be the only type
-------
of anchors that could neet these tv.-o requirements -n^ still ^.tisfy
general guidelines for the systen.
To deulov f.iiH s-'Steo Affective! v vif.ho'it "iv^rs anri t/irnin
SbiTQintS 0~ wi'rc ClcS'i^iii uul C
-------
ratio, and their ability to be installed rapidly in comparison to alternate
anchoring systems. The anchor assembly weighs approximately 100 Ib in the
ready-to-fire configuration. The anchor itself weighs only 25 Ib and has a
confirmed vertical pull-out force of at least 10,000 Ib for sanrl and nud
installations. The same anchor system can be used with a different anchor
point for rock installation.
Two methods for firing the anchor are available. One method is the
remote electrical method described here and the other is a bottom contact
method. The electrical method was selected because it was believed that
the anchors could be placed more accurately using this method. For in-
stance, if the anchor is not set on the bottom initially, it can be picked
up and relocated before firing. The contact-type anchor fires immediately
on touching the bottom. Deadweight or other types of anchors can be used
as an emergency anchoring system, if the current velocity in the watercourse
is low.
Deployment Subsystem
This subsystem includes special devices for pulling the barrier to the
bottom and mooring it to the anchor pendants, equipment for filling the air
and water bladders, vessel(s) for deploying the barrier, and marker buoys
and anchors for temporarily mooring the barrier.
Figure 2 illustrates the gripper devices used to pull the barrier to
the bottom and moor the barrier to the anchor pendant. The pull-down grip
is first put on the anchor pendant. This grip is permitted to free-fall or
is lowered down the anchor pendant until it reaches bottom. Both ends of
the pull-down line are maintained on the surface during this procedure.
When the pull-down grip is on the bottom, the end of the pull-down line is
attached to a bail located on the mooring grip, and the top of the mooring
grip is attached to an anchor ring on the barrier. When the free end of
the pull-down line is pulled on, the barrier will move down the anchor
pendant. The grips are designed to slide when moved in one direction on a
cable and to be self-activating when pulled in the other direction.
The mooring grip has a rated strength of 15,000 Ib. To check this
figure and assure that the grip would function properly on the particular
type of wire rope used for the anchor pendant, a structural test was per-
formed. The grip was installed on a length of the wire rope and was put on
a hydraulic tensile testing machine. The machine loaded the grip and wire
rope with a force of 15,000 Ib without any malfunction or apparent struc-
tural damage to the grip or wire rope.
Five lightweight-type (LWT) anchors are used to moor the barrier in a
temporary position while the explosive anchors are installed. Each
temporary mooring line to be used with these anchors should be at least 100
ft long so that the anchor can develop full holding power. The preferred
line for this use is 3/8-in. diameter, braided nylon line. The braided
line is much easier to work with and is stronger than twisted line.
Five buoys of at least 50 Ib buoyancy are required for supporting the
8
-------
TO BOAT
FIRING LINE
RECOVERY LINE
TO BOAT
ANCHOR LINE
SHACKLE
HYDROSTATIC ARMED
REMOTE ELECTRIC FUSE
CABLE PEA/OANT
ANCHOR
Figure 1. Vertohold embedment anchor-remote (electric) placement,
-------
TO -DAVIT
[ON 00AT)
HAULING X1
PART \
(TO OOAT)
BARRIER (PACKAGED)
ANCHOR PENDANT
SURFACE
TO ANCHOR
Figure 2. Pull-down schematic.
10
-------
anchor pendants and pull-down devices during deployment operations. These
buoys should have a 3-ft line v/ith snap hooks attached so that they can he
easily installed on the pendants. In addition, five smaller buoys of about
20 Ib buoyancy are required to support the five ends of the pull-down lines.
A small boat equipped with an outboard motor is required for installa-
tion of the barrier system. This boat should have at least a 1000 Ib rated
load capacity and should be equipped with an outboard motor of at least 5
hp if used to deploy the barrier in still water. If the barrier is to be
deployed in a watercourse where there is a current, a larger boat is re-
quired for towing the barrier. Preferably, two boats should be available
for deployment of the barrier system.
The boat should be fitted with a device capable of lifting a 200 to
300 Ib load to a height of 5 ft and moving it over the bow of the boat.
This device must be equipped v/ith a hand winch v/ith at least 50 ft of line
for lowering the anchor to the bottom. An unmodified grip of the size used
for the pull-down grip should be available for attachment to the end of the
winch line so that the anchor pendant can be gripped and pulled taut.
The air compressor/water pump unit required for inflation of the
barrier flotation collar and filling of the bladder seal is powered by a
6.5 hp gasoline engine. It includes a direct-coupled rotary air pump with
a rated delivery of 14 SCFM at 10 psig and a clutch-coupled water pump with
a rated delivery of 125 gpm at a 20-ft head. Shop tests of the unit found
that the delivered volumes were 10 SCFM at 10 psig for the air compressor
and 100 gpm at a 20-ft head for the water pump, which were the original
specifications.
Bear Lake Test
Preliminary tests were conducted in September 1971 at Bear Lake to
introduce and train Ocean System, Inc. personnel in the correct assembly
and field use of the explosive embedment anchors and to test the pull-down
device that was under development at the time. Two Ocean Systems, Inc.
personnel and two EDO Western Corporation personnel participated in the
test.
11
-------
SECTION 5
PROTOTYPE FIELD TESTS .
Three field tests of the prototype barrier were conducted betv/een
October 1, 1971 and April 30, 1972. The first test was conducted in a lake
in West Virginia. The second test was conducted in the lower Potomac River
in Virginia; however, adverse weather forced cancellation of this test
before it could be completed and, as a result, a third test of the barrier
was conducted in Florida.
WEST VIRGINIA FIELD TEST
A small private lake located at Sugar Grove, West Virginia, v/as
selected as the test site at which to evaluate the barrier and deployment
techniques under still water conditions. It was necessary to use this
lake, which is approximately 150 miles from Ocean Systems' Reston, Virginia
facility, because of problems in obtaining permission to use a local lake
for the test. Most of the difficulties were due to apprehension on the
part of the owners concerning the use of the explosive anchors and
Rhodamine-B fluorescent dye in the test.
POTOMAC RIVER FIELD TEST
The lower Potomac River southeast of Colonial Beach, Virginia, was
selected as the location for the second test. This particular area of the
Potomac River was selected because it afforded the correct depth, currents,
and bottom conditions required to subject the barrier and deployment tech-
niques to more severe environmental conditions than those experienced at
the lake site in Sugar Grove, West Virginia. Slightly modified deployment
techniques, reflecting results of the previous test, were used in this test.
Because the barrier deployment site was approximately 7 mi from the
shore base, it was necessary to transport the packaged barrier to the
deployment site, rather than tow it to the site as was done in the lake
test. To accomplish this, a small catamaran platform about 18 ft long v/as
designed and constructed. This platform incorporated the gantry used on
the small boat in the lake test, a large box for the packaged barrier, and
a set of large rollers for launching and retrieving the barrier; the
platform was not powered.
The barrier system was prepared for deployment the week before the
test. The barrier was dried in the sun, and the air and water bladders
were filled and inspected for leaks. A number of small tears were located
and easily repaired using fabric patches and cement. The barrier was then
f#tti?"j"
12
-------
repackaged. The foam flotation used in the lake test was left out of the
packaged barrier, but a 3/3-in. nylon rip cord was included. With the foam
flotation omitted, the barrier was much easier to package and handle.
Preparation of the other equipment needed for deployment v/as
accomplished according to the same general procedures used in the previous
test. Extra batteries for firing the anchors and extra materials for
cleaning the anchor fuze bodies were packed with the anchor system. In
addition, load cells for two of the mooring legs and a current meter with a
recorder output were included with the test equipment.
PALM BEACH FIELD TEST
Because of the premature termination of the second field test
(described later), a third field test was conducted near Lake Worth Inlet,
Palm Beach, Florida. The reasons that this test was conducted at this
location were that tidal currents of 1 to 2 knots were available and there
was good underwater visibility for observation of certain stages of
deployment and aspects of the in-place barrier.
During the week before the test, the barrier was again inspected,
repaired, and repackaged. Several of the plastic hose-to-pipe fittings on
the air bladder penetrations were found to be broken and were replaced.
The foam flotation that was removed after the first field test was replaced,
and the nylon rip cord was replaced with a polypropylene rip cord which
would float when free of the barrier. The masking tape bindings were re-
placed with 1.5-in. wide fiber duct tape. This tape was put on two layers
thick for most of the barrier and three layers thick at points where higher
stresses might occur. By experimentation, it was found that this tape was
readily torn by the rip cord.
Five fuze bodies for the explosive anchors were obtained from EDO
Western Corporation. Each of these was completely assembled and readied
for use. Two anchors were assembled to the extent that all that was
required to render them ready for use was to load the powder charge, mount
them on their firing stands, and connect the anchor pendant. Thus, two of
the anchors could be deployed quickly and only a portion of the total
refurbishment procedure would have to be performed to ready additional
anchors for firing. The difficult and time-consuming task of refurbishing
the fuze body would already be accomplished.
EVALUATION OF PROTOTYPE SYSTEM
Deployment
For evaluation purposes, deployment of the barrier has been divided
into four steps, each of which is essentially independent of but sequential
to the others.
Temporary Mooring--
In the beginning of the program, it was thought that the best way to
accurately install the explosive anchors was to moor the barrier temporarily
13
-------
in place on the surface and then use the barrier as a pattern for placing
the anchors. To use the barrier as a pattern for placing the anchors, it
nust (1) arrive at the scene of the spill with or before the explosive
-r,cuors, (2) be pulled very taut so that the anchor pattern win r>e accurate
atl- :, - ^toi.i of the barrier will be pulled tight (which is required for a
good bottom seal) when the barrier is permanently moored, and (3) be left
in place on the surface while the explosive anchors are being installed.
In the first test of the system on the still lake (West Virginia),
temporary mooring of the barrier presented no problem. It was towed 600 ft
to the deployment site and moored in approximately 40 min by 2 men in a
12-ft boat equipped with a 5 hp outboard motor. During the second test in
open water (Potomac River), mooring the barrier proved somewhat more
difficult, taking approximately 80 min. During this test, the river was
flowing at approximately 1 knot, and positioning of the barrier with the
small boat was more difficult. In addition, the motions of the barrier
caused by waves made it impossible to pull the barrier as taut as in the
first test. Because of problems associated with the explosive anchors and
insufficient daylight, it was not possible to install all of the anchors
during the first day, and as a result, the barrier was left in the
temporary moor for the night. Winds and waves caused by bad weather broke
the tape bindings on the barrier during the evening and, as a result, the
barrier became unfurled. The test was discontinued, and the barrier was
recovered.
For the third field test (Palm Beach, Florida), a "template" was used
instead of the barrier for accurately placing the anchors. The template
worked very well and was pulled taut even though there was a current of
approximately 1 knot and small waves. Mooring of this template required
approximately the same amount of time as was required for mooring the
barrier in the first test. The explosive anchors were placed very
accurately, but replacement of the template with the barrier after the
anchors had been installed required about the same amount of time as was
required to moor the template. Thus, the explosive anchors were placed
more accurately, and the barrier was not put into the water until the
explosive anchors were in place. However, an additional 40 min v/ere
consumed using this procedure.
As a result of these experiences, we believe that the best plan is to
include the template as part of the deployment system, but only to be used
as the situation requires. This decision will have to be made by the
On-Scene Coordinator. As an example, if the explosive anchors (because of
their lighter weight) can reach the spill scene hours before the barrier,
then it would be advisable to install the explosive anchors using the
template while waiting for the barrier to arrive.
The time required to install the barrier or template in a temporary
moor is reasonable considering the small, slow boat used for the job. If a
slightly larger and more powerful boat with a reverse drive (the 5 hp motor
used in the field test did not have reverse drive) were used, the time prob-
ably could be shortened by 10 to 15 min because the boat could move around
faster and maneuver better.
14
-------
Explosive Anchors—
The installation of the explosive anchors is the single most time-
consuming portion of deployment and is also that portion that offers the
opportunity for the greatest reduction in tine. Tvro seonents n-f tha
installation can be discussed individually.
The first segment is the actual installation of the anchors, i.e., the
time from which the boat with the anchors leaves shore, the anchors are
installed, and the boat returns to shore. In the field tests, all of the
anchors were installed using the small boat equipped with a 5 hp outboard
motor and a lightweight gantry with a hand winch. Because the motor did not
have a reverse drive, it was difficult to maneuver the boat in a current.
This was aggravated by the fact that it took about 5 nrin to lower the
anchors to the bottom because the electrical leads and firing line had to be
taped to the lowering line. Retrieving the gun barrel and stand (75 Ib
combined weight) (after firing the anchors) took longer than lowering the
anchors. In addition, time was required to connect the firing line to the
firing box and fire the anchors.
If the bottom-contact-fired anchors were used rather than the.remote
electrically fired type, approximately 10 min could be saved at each firing.
It should be realized that this type anchor must be placed accurately the
first time, since it fires upon initial contact with the bottom. With a
reasonable amount of practice dropping a dummy anchor in waves and currents,
the skill of the boat operator could be developed to assure a high proba-
bility of accurate placement of the anchors. The possibility of an
occasional inaccurate placement of an anchor is thought to be a good tradeoff
against the time saved by using bottom-contact-fired anchors. The heavy
stands, firing box, and firing cable also would not be required.
The other segment of anchor installation that requires a large amount of
time, 30 to 40 min per installation, is refurbishing or rebuilding the anchor
gun after each firing. Based on the field tests, we believe that five com-
pletely ready-to-fire anchors and one spare should be used in deploying the
barrier. These anchors should have the anchor pendants attached and should
be packed in individual boxes for ease of handling. The main powder charge
should be left out of the gun barrel, but should be packed in the same box
as the anchor. All that should be required to ready an anchor for firing
would be to install the powder charge and load the anchor on the boat.
If the suggestions mentioned above were implemented, we believe that
the time required to install an anchor, including a short over-water
transit, could be reduced from approximately one hr to 15 to 20 min. Based
on the experience of the field tests, it is evident that functionally (i.e.,
firing and penetration), the anchors operated exceptionally well. They are
very well suited for their intended application.
Pull-Down--
Both the pull-down grip and the mooring grip worked very well, although
there are some modifications that could be made to the grips that would make
their installation much easier and probably cut the total time for installa-
tion of the mooring devices from approximately 1 hr to about 30 min.
15
-------
As presently constructed, the grips nust be slipped on the end of the
anchor pendant because the grips have fixed tabs on the sides to prevent
the grips from coning off the cable. If these tabs were modified so that
•chev were Movable, the qrios could be sliooed on the anchor pendant side-
Wuy 3 9 Wn 1 C n t'Guiu ^uVG i*l iiiC •
Also, if the shackle on top of the mooring grip were replaced with
some type of quick-connecting hook, this grip would be easier to connect to
the anchor's ring on the barrier. In addition, some type of quick attach-
ment device on the bail of the mooring grip would make attachment of the
end of the pull-down line quicker. The present method requires that the
line be knotted and then taped to prevent the knot from possibly becoming
untied. In making both of these modifications, it should be realized that
it is very important to minimize the combined height of the pull-down grip
and the mooring grip, since the strength belt on the barrier (Figure 3)
cannot be brought any closer to the bottom than this distance.
The force required to pull down the barrier was somewhat larger than
anticipated. The addition of another winch on the deployment vessel would
facilitate pull-down of the barrier. This winch would not have to be
mounted on the gantry frame, but preferably would be mounted low in the
boat so that the end of the pull-down line could be brought over the stern
of the boat and onto the winch. If another boat with a more powerful motor
is available, such as was used in the Palm Beach Field Test, this boat can
be used to pull down the barrier.
Another small problem that occurred was that two of the pull-down
grips did not fall all the way to the bottom of the anchor pendant when:
installed because of kinks in the wire anchor pendant. A diver found it an
easy job to slide the grips over the kink, and this problem can be easily
solved in the future by maintaining a strong tension on the pendant while
sliding the pull-down grip to the bottom.
Inflation—
The time required to inflate the flotation collar fully was approxi-
mately 1 hr using a 10 SCFM compressor. This time could be reduced signifi-
cantly by simply supplying air at a higher rate. One means would be to: use
regulated air from compressed air cylinders. The capacity of the flotation
collar is approximately 600 ft^, which is the equivalent to the air con-
tained in 9 standard SCUBA diving tanks or two large "T" cylinders. The
combined weight of enough of either of these cylinders to supply the air
would be less than 250 Ib. Using compressed air cylinders, the time
required to inflate the barrier could probably be reduced to about 10
minutes. This is a tradeoff that should be considered for an operational
unit.
The most serious problem concerning inflation of the barrier was that
the air bladders leaked, and, as a result, the flotation collar could not
be filled with air. This problem, although serious, can readily be solved
with changes in the design and materials of the flotation collar or by
intermittent pumping. Even if compressed air is used to inflate the
flotation collar, an air compressor should still be on hand for use in the
16
-------
INFLATION LINE-
FLOTATION COLLAR
GROMMETS
ROPE FOR LACING
WATER HOSE TO SURFACE
RELIEF VALVE
— HOSE CONNECTION
1—STRENGTH BELT
ANCHOR POINT
WATER INFLATED SEAL
Figure 3. Details of barrier construction,
17
-------
event that the collar develops a leak. The 10 SCFH compressor supplied
with the system is sufficient to keep up with snail leaks, but, if time
permits, a larger one should be obtained once the barrier is deployed.
A less serious problem which occurred during the first test was that
some of the tape bindings did not break. During the third test, this did
not appear to be a problem because the barrier was pulled down tight
against the bottom. When inflation began during the third test, the
barrier immediately "popped" to the surface; however, because of leaks in
the flotation collar, it did not continue to rise, and the rip cord that
was installed after the first test was used to break the bindings. It is
suspected that if the flotation had not leaked, the barrier would have
"popped" up without the use of the rip cord; however, it is advisable to
retain the rip cord in the packaged barrier as an added measure of safety.
The time required to fill the bladder seal on the bottom of the barrier
is dependent on the rate at which liquid is pumped into it. The bladder
has a capacity of approximately 10,000 gal. There are no easy solutions to
shorten the time required to fill this bladder since any equipment that will
pump liquid at a high enough rate to fill the bladder in a short time will
also be heavy. In addition, it is not as important that the seal bladder
be filled as quickly as the air bladder, unless the spilled or leaking
substance has a low solubility and is more dense than water. The best
solution for filling the seal bladder probably is to include the 100 gpm
water pump with the system, and to try to locate a larger pump near the
site of the spill. Preferably, this will be a mud pump so that the seal
bladder can be filled with sand or mud to weigh it down.
Ability of Barrier to Contain a Spill
The ability of the barrier to contain the spilled hazardous material
is dependent upon the "tightness" with which the barrier encloses the spill
source and the ability of the barrier to maintain its structural integrity.
The barrier did not maintain its structural integrity in the third field
test; however, it is believed that this problem can be corrected. Because
of the structural failure of the barrier, there was no opportunity to put
dye inside the barrier during the Palm Beach Field Test. However, visual
inspection by a diver indicated that the barrier was pulled down tight
against the bottom for its full circumference and there would be little
chance for pollutants inside the barrier to leak out. This observation
confirmed the results t>f the still water test at Sugar Grove, West Virginia,
when enough Rhodomine-B fluorescent dye was put inside the barrier to form
a deep red solution. For the next 22 hr, the water around the barrier v/as
checked for dye using a fluorometer capable of detecting a few parts of dye
per billion parts of water. No dye was detected, which indicates that the
barrier would contain a pollutant.
Visual observation of the barrier at the time of failure in the 1972
Palm Beach test indicated that the barrier wall tore initially in the
vicinity of anchor No. 1. The barrier wall continued to tear away from the
strength belt for almost the full circumference of the barrier until the
barrier was "feathered" in the current and the dynamic load was released.
• 18
-------
Close inspection of the barrier after the test indicated that the initial
tear probably occurred at a sewn seam where the barrier wall was attached
to the strength belt. At this sewn seam, the barrier v/all was conorised of
two thicknesses of fabric sewn on each side of t!?2 str?rc?th ^l4-. T^ro
-*». two pieces of fabric were joined in an electronically welded joint above
and below the strength belt. Above the welded joint located above the
strength belt, the barrier wall was a single layer of fabric (Figure 3).
It is believed that dynamic pressure on the barrier wall caused the
fabric to pull very hard at the sewn seam. The pressure of the stitches on
the fabric caused the fabric to begin to fail in a tensile mode. As soon
as a short length of the wall had failed in this mode, the fabric began to
fail in a tear mode. The fabric will, of course, faij much easier in the
tear mode since all of the load is put on the few f-Bers at the tear point.
After tearing for a few yards through the double layer of material at the
sewn seam, the tear jumped up the barrier wall just above the welded joint
where it continued for the circumference of the barrier.
In the direction of the No. 5 anchor, the tear spread for almost the
full length of the barrier, while in the direction of the No. 2 anchor it
went only approximately 20 ft until it was checked by the 2-in. webbing in
the vertical joint. Here it continued upward along the webbing until it
reached a point just under the flotation collar. That the tear was checked
by the 2-in. webbing and then ran up alongside the webbing, suggests that
had vertical belts been Included in the barrier, they would not have
prevented failure.
*» Another area of the barrier design where failure occurred is that of
^ the seams in the bladders. The barrier, as presently designed and con-
structed, uses a simple type of seam for the bladders. Although this seam
has an adequate vertical strength, and material tests during the construc-
tion of the barrier indicated adequate strength of the joint, the electronic
weld did fail by peeling and the row of stitching down the middle of the
electronic weld prevented the bladder from bursting. The flotation collar
was pneumatically tested after construction by pumping it up with the air
compressor until the relief valves vented. All of the valves operated
properly, which indicates that failure of the seam was not caused by
overpressurization. Instead, it is believed that the electronic weld
"peeled" in a long-term creep mode when the bladders were pressurized
during the first field test.
Construction of the bladders using an improved type of joint will
solve this problem and will decrease the strength of the bladder signifi-
cantly. The only disadvantage of using this method is that it is more
costly.
The laced joint with seal-flap performed very well during the tests.
At no time did the Velcro fastener material used to fasten the seal come
apart. This was true even during the second field test in the Potomac
River when the barrier was retrieved from the water without undoing the
vertical seam, which involved much handling of the barrier. The only
disadvantage of the laced seam is that it would be rather difficult and
:&&#•
w> 19
-------
time-consuming to put together when the ends of the barrier nust be joined
during deployment, as would be the case if the barrier were being deployed
around a large spill source that was protruding above the water surface and
there were no way to lift the barrier over the source. In this case, it
would be better if the barrier were fitted with a large zippar. Sucn .:
zipper, ruggedly constructed of nylon, can have a tensile strength perpen-
dicular to its length of over 300 Ib/in.
The material that was used for construction of the barrier, Herculite
"20," was obviously not of sufficient strength, at least in the areas where
failure occurred. Nevertheless, after being handled and deployed three
times, the material did not show a significant amount of wear and tear from
these operations, except for some small tears and abraded spots on the air
bladder. Although oth»r materials should be considered if the barrier is
redesigned, the Herculite material should be a prime candidate. It has a
higher tear strength>than most other materials of equivalent weight and is
available in stronger and more abrasion-resistant grades.
The structural design, if made adequate for low current conditions,
probably also will be adequate for small wave conditions, such as were ob-
served in the third field test. The barrier was observed to be essentially
transparent to the waves observed in this test (heights up to 2 ft, wave
length 5 to 50 ft). As long as sufficient slack is available in the barrier
skirt, the surface flotation should conform closely to the water surface and
not create significant dynamic loads on the barrier.
As a final comment on the structural design of the barrier, it should
be noted that the barrier is not yet an optimized design and does not
represent the end-product of a significant design effort. Although it did
not perform as well as desired or expected, it was useful in evaluating the
operational aspects of deploying the barrier, which was the primary purpose
of the program. With the proper design effort, the barrier could be made
to work properly and to have the desired structural integrity.
20
-------
SECTION 6
FIELD DEMONSTRATION OF THE MODIFIED BARRIER
Phases 1 and 2 of this project were completed in May 1972. This was
followed by Phase 3 wherein a new barrier was fabricated which incorporated
the recommendations of Phases 1 and 2. These modifications and improvements
to the new barrier were as follows:
The Herculite "20" fabric was replaced by a heavier type known as
Herculite "LR-210."
The flotation collar was reinforced by doubling the fabric.
The area around the strength belt was reinforced by doubling the
fabric.
The anchoring points were reinforced more heavily.
Quality control of the electronically welded joints was much more
rigorous.
****" Field demonstration tests, consisting of two deployments and recoveries of
the newly fabricated barrier, were then carried out between June 9 and
July 6, 1976.
The test site was located in Lake Worth, a coast-parallel back-barrier
lagoon located between the towns of Palm Beach and Riviera Beach, in
Florida (Figure 4). The site was selected because of (1) appropriate water
depth (25 ft), (2) water clarity on flood tide suitable for photographic
documentation, (3) currents up to 2 knots, (4) accessibility to support
facilities, (5) protection from severe storms, and (6) the opportunity to
compare results with those of a previous test conducted at this site in
1972.
Changes in regulations since 1972 made it necessary to obtain permits
from local, state, and federal agencies before conducting the tests. Local
objections to the use of propel!ant anchors required that the test program
be modified if this site was to be used. A decision was made to "jet" mush-
room anchors into the lagoon bottom to overcome these objections. The pro-
pel! ant anchoring system had been tested successfully on several earlier
occasions and, although an integral part of the total system, its use could
be avoided for this test. Local objections to the test were then dropped
and the necessary permits granted.
21
-------
en
(U
x:
u
rt
0)
ffl
22
-------
The test program consisted of two deployments and recoveries. The
first test was not completely successful because only partial deployment
occurred. Nevertheless, the experience gained in handling the HMB system
was extremely valuable in the second test and a marked improvement in
deployment ease was noted.
The HMB arrived in Riviera Beach in early June 1976 and was unloaded
from an enclosed van. It was immediately apparent that the most difficult
problem associated with the HMB would be that of handling. This was to be
proved in every aspect of the testing program. Loading the packaged HMB
into the van had required two forklifts; unloading it with one forklift was
difficult and took approximately 1.5 hr with five men.
The first site selected was changed when divers uncovered a large
object where the barrier wall would have been positioned. The bottom of
the alternate site was relatively flat, consisting of compact sand with a
thin veneer of fine, loose sand. The only obstruction was a partially
buried 55 gal drum. Two mushroom anchors were jetted in 5 ft deep at each
of the five anchor points. The anchors were 30 in. in diameter. Installa-
tion of the anchors required 10 hr.
After flotation was attached to the folded barrier, it was offloaded
from a van directly into the water using a crane mounted on the stern of a
vessel moored at the adjacent pier (Figure 5). It was necessary to take
the HMB under tow immediately to prevent it from tangling in the pilings of
the pier. During the approximately 25 min while the HMB was being towed to
the site, only two-thirds of the barrier was on the surface. Once at the
site, additional flotation was added to the barrier to prevent it from
sinking. ;
All mooring pendants were attached to the anchors, and the pull-down
procedure begun. Some difficulty was encountered because of air trapped in
folds of the HMB and an anchor which was pulled out by the upward force of
the overly buoyant HMB. The anchor was replaced.
Pull-down was .completed early on the next morning. When the rip cord
was pulled to break the tape binding holding the barrier together, the tape
refused to break arid diver assistance was required. Inflation of the
flotation bladders was then begun. Inspection by divers soon revealed a
double twist in the barrier, preventing proper deployment and blocking the
air from entering the remainder of the flotation bladder. Inflation was
halted. Attempts to untwist the HMB were fruitless and immediate steps
were taken to bind the barrier together as much as possible before the
strong ebb tide currents began. During this operation, it was noted that
several anchors had pulled out under the upward force of the twisted
barrier. The currents were strong at that time, and only by extraordinary
action of the handling team was loss of the HMB prevented when the last
anchor was released. The partially unfolded barrier was extremely difficult
to handle in the swift current and return to shore required approximately 2
hr. (Subsequent analysis suggested that improper folding was the probable
reason for the twisting.) Removing the HMB from the water required seven
men working 8 hr with a forklift and a crane, once again emphasizing the
23
-------
Figure 5. Unloading the HMB from the van to the water.
24
-------
extreme difficulty of handling the HMB, particularly in moving it out of
water.
The HMB was inspected for damage. Although there was no major struc-
tural damage, nine holes were observed in the air bladders, as well as
several defective welds, numerous small holes in the water bladder, and
small rips in the Herculite material near the anchor "D" rings. Repairs
were made.
Discussion of the first field trial attempt produced two major changes
in the deployment procedures for the second test. First, the anchoring
system was changed to three equally spaced mushroom anchors at each of the
five points. (It was believed that the single center point allowed the
anchors to slip sideways under lateral forces and work themselves up out of
the bottom.) The second change involved the towing procedure. For the
second test, the folded barrier bundle would be towed by one "D" ring, with
the other opposing- "D" rings secured together to prevent twisting during
the tow.
After the decision was made to proceed with the second test using
these modifications, the HMB was refolded. This was by far the most
physically demanding task in the entire operation. Many problems were
encountered in the folding process, mainly because of inexperience. Seven
men were used in the folding, but the compact accordian folds necessary for
proper deployment and to avoi d trapped ai r, twi sti ng, etc. were not
achieved on the first attempt. After the folding was repeated success-
fully, the bundle was taped together and flotation added. The ends of the
bundle were brought together and laced, as shown in Figure 6. The new
mushroom anchors were positioned at the test site.
On June 28, 1976 all boats were readied and the HMB was placed in the
water at 0830 hr. This took 30 min using an overhead crane to unload the
HMB. By 0900 hr the HMB was under tow to the site where it arrived at 0930
hr (Figure 7). The lines holding the HMB together to prevent twisting
during the tow were taken off (Figure 8) and the first "D" ring attached to
the mooring pendant. Pull-down began at the northern-most point and
continued without major difficulty to completion at 1500 hr, a total of
approximately 5 hr. Figure 9 shows the pull-down grip being attached to
the mooring pendant. Figure 10 shows an underwater view of the pulldown
process beginning. In Figure 11, the HMB is being pulled down with the
winch system. Figure 12 shows the HMB partially pulled down and Figure 13
shows the HMB after subsequent pull-down. The thin white line near the
bottom is the template used to position the anchors. When pull-down was
completed, the system was ready to be inflated.
Even though the rip cord had been changed to 0.5 in. manila line,
attempts to pull the rip cord from the surface failed again as the line
only rolled the tape. It was again necessary for a diver to break all but
two of the tape bindings. Inflation of the air bladders began, but one of
the air lines kinked and a diver had to free the line. Figure 14 shows the
last portion of the bladder being inflated. Several small leaks were
located in the air bladder and the relief valves leaked as well, possibly
25
-------
Figure 6.
Lacing air bladders
together.
Figure 7.
HMB being towed to test
site. Note the air
inflation umbilical on
top.
26
-------
Figure 8.
Diver releasing lines holding "D" rings together
for towing.
Figure 9.
Pull-down grip being
attached to the
mooring pendant.
27
-------
Figure 10. Underwater view of pull-down commencing.
Figure 11. Winching down the HMB.
28
-------
Figure 12. HMB partially pulled down.
Figure 13. Full pull-down
at two adjacent anchors.
Note the upward strain
caused by the flotation.
Also note the template
(thin white line) near the
bottom used in placing the
anchors.
29
-------
Figure 14. Nearly inflated HMB on surface.
Figure 15. Fully inflated bottom seal rising above lake floor.
30
-------
due to their 0.5 psi over-pressure setting. The worst air leak was at the
end of the orange air bladder inside a welded flap and was impossible to
patch without destroying the weld. The air compressor ran for approximately
10 min out of every hour to counter air losses through the leaks. The
barrier was on the surface by 1600 hr (Figure 15) at which time the water
*"'* pump was connected, and water was pumped into the bottom seal bladder.
Filling of the water bladder was also slowed because of repeated kinking of
the fire hose used.
On the following day, inspection of the HMB revealed the water bladder
to be four-fifths full, but not sealed against the bottom (Figure 16). Two
anchors were also discovered to have pulled out of the bottom during the
night. These were the old, center-attached anchors. None of the new,
three-point anchors had pulled loose, and the barrier was in no danger of
breaking away. The anchors that pulled out were on the south side of the
barrier, which received the strongest force from the ebb tide. The
dynamometer readings showed a maximum of 2000 Ib of force had been reached
during the night. The ebb tide currents began increasing early in.the
afternoon. By 1400 hr the barrier had begun changing shape, and it was
completely collapsed by 1500 hr (Figure 17). Current velocities during
this period are reported in the Appendix. The HMB could not be forced open
and field operations were suspended for the day. In spite of this problem,
it was decided to weigh down the bottom seal bladder with lead bars and
attempt a dye experiment to determine any leakage points.
On the morning of June 30, 1976, the barrier was found collapsed again,
although it had been observed to have opened up during the slack current the
previous evening. However, within a short time, the barrier once again re-
gained its circular shape without assistance. Divers placed 1000 Ib of lead
bars in the space between the HMB wall and the water bladder to seal the
barrier against the bottom. Rhodamine-B fluorescent dye was placed inside
the HMB at 1305 hr and current meter and fluorometer readings were taken
continuously in and around the HMB during the ebb tide. As the current
increased, the barrier again began changing configuration. By 1505 hr, the
south side of the barrier facing the ebb current was pushed completely
underwater and all the dye was lost. Measurable amounts of dye also were
detected within 4 ft of the bottom, downstream of the barrier, indicating
that the bottom seal was incomplete, and water was being lost under the
seal. Subsequent investigation by divers revealed that the anchors on the
southeast section had pulled out, leaving the bottom seal of the barrier
about 5 ft above the bottom of the lagoon, thus allowing sufficient water
inside to maintain pressure against the lee wall. The field test of the
HMB was discontinued at that time.
The recovery process began the following day by removing the lead bars and
disconnecting all but one anchor point. Several slashes were made in the
bottom seal bladder to allow the water to exit while the barrier was under
tow. When the final anchor was cut loose, it was impossible to tow the
barrier, even against the weak flood tide current. The HMB wall was acting
like an enormous sea anchor and had to be slashed to allow water to escape
through the rear. An attempt also was made to cinch up the wall to the
flotation bladder, but the mass of the curtain was too great to be moved
C 31
-------
Figure 16. Fully collapsed HMB. Current was from left to right.
rr
Figure 17. Tears around "D" ring.
32
-------
manually. It took 2.5 hr to move the barrier to the shore base. Another 2
hr of effort by 5 men and an overhead crane was required to lift the HMB
from the water onto a flatbed truck.
Inspection later revealed some structural damage, peeling welds, and
several holes to the air and bottom seal bladders and the curtain wall, in
addition to the intentional slashes. The barrier was folded and stored on
a pallet pending further action.
SYSTEM EVALUATION
Temporary Mooring
~«- The template marking the deployment positions for the anchors was
staked out on the bottom instead of in its normal, floating position because
', of the alternate anchoring system being installed by the divers. Used in
this manner, the template was very effective^in guiding the divers.
Anchoring
The preferred propellant anchoring system was not used in this test
because of permit restrictions, as previously explained. The mushroom
anchoring system actually used was an expedient measure and was not eval-
uated as part of the test. Earlier tests had shown that the propellant
anchoring system was workable and was probably superior to the anchors
being used in the field tests, as was confirmed by the failure of several
anchors during the two tests.
Pull-down
'**»,» ^~~~
Both the pull-down and the mooring grips worked well. The weakest part
of the pull-down system was the winch. The winch used in the test was a
simple two-gear boat trailer winch that did not have the strength nor the
durability for this application. It was impossible to pull the mooring
pendants taut under even a slight current using this system. This
prevented several pull-down grips from falling all the way to the bottom,
and diver assistance was required.
In the initial test, air trapped in the HMB, combined with strong
lateral forces imposed by the strong tidal currents, made pull-down ex-
tremely difficult and even caused anchors to pull out. During the second
test, extra flotation had been added, and this contributed to the difficulty
even though little air was trapped in the folded barrier. The flotation
could not be removed prior to pull-down because the tape binding the HMB
also held the flotation. An alternate method of binding and attaching
flotation should be found.
Pull-down for the first test, with all its problems, took 8 hr and
required 6 men. The second test pull-down, after corrective measures had
been taken, still required 5.5 hr using 5 men.
33
-------
Inflation
The biggest problem encountered during inflation occurred during the
first test when a twist in the barrier prevented complete inflation and
cancel"!^ •';!".-: ."-.- .::.rjer of the test. Careful attention to repacking the
"*•** HMB solved this proclem. Another problem during both tests was breaking
the tape bindings holding the HMB bundle together. In both deployment
tests, using either a smooth, braided nylon rope or a rough, manila rope,
respectively, as a rip cord, diver assistance still was required to cut the
tape and release the HMB.
Both bottled air and a compressor were evaluated as a source of the
air to inflate the upper bladder. For example, a bank of five "K" bottles,
each holding 220 ft^ of compressed air, is sufficient to inflate the
bladder. The air compressor has the advantage that it can also be used to
maintain pressure in case of leaks. Thus, in the second trial, the air
compressor was operated for approximately 10 min every hour to keep the air
bladder full, even with several small leaks.
As with the air hose, diver inspection found the water hose to the
bottom seal bladder kinked near the intake opening. Water pressure from
the pump was not adequate to hold the kink open until a larger pump was
substituted. However, the bottom seal failed to function as designed when
filled with water. Obviously, a higher density fluid must be pumped into
the bladder to provide an effective seal against the bottom. This fluid
could be a sand slurry, drilling mud, or some other dense medium. Obtaining
such a material in a spill situation could present a logistical problem. In
addition, some air is inevitably trapped in the bladder and causes it to
arch up between the anchor points. Valves should be installed to bleed off
this trapped air.
Recovery
The HMB represents a substantial economic investment and, to be cost
effective, it must be recovered - with minimal damage - to be used again.
The initial step in recovery is to drain the bottom seal bladder.
This was done in the trials by cutting vertical slits in the bladder so
that the dynamic pressure during towing caused the bladder to collapse and
force the trapped water out through the slits. Special valves should be
incorporated into an operational barrier design to allow the bladder to be
purged with air or completely opened for the liquid inside to escape.
After the bottom seal is drained, the anchors on the downstream side
of the barrier are released by a diver unshackling the barrier "D" rings
from the pull-down grips. The final anchor is released only when the tow
boat is in position and ready. This operation can be expedited by replacing
the final shackle with a strong rope just before removal and then having the
diver cut the rope.
It had been suggested earlier that the lacing holding the ends of the
HMB together could be cut and the HMB recovered more easily by towing a
,,/MSife..
34
-------
single strand. This was found to be impractical because the 200 ft length
would have been uncontrollable in the currents and it could not nave been
maneuvered around channel markers, anchored vessels and pilings. In
general, towing of the HMB should be avoided if possible. A crane also
must be available to lift the HMB from the water at the shori? bass, since
it is too heavy to be recovered manually.
STRUCTURAL DESIGN
The structural design improvements incorporated into the HMB since the
1972 tests were highly successful. No major failures occurred in the
Herculite LR-210 film except during recovery. Several of the electronic
welds did fail by "peeling", but none of these was at a critical point.
INSPECTION, REFURBISHING, AND REPACKAGING OF SYSTEM
One year later, on July 1, 1977, the barrier was laid out at the large
Perry Oceanographic Warehouse at Riviera Beach, Florida and inspected for
damage. Aside from the deliberate slashes in the barrier wall and the
bottom seal bladder made to facilitate recovery and towing, and several
smaller tears around the "D" rings (Figure 18), the barrier was in good
condition. The auxiliary equipment was also inspected and found to be in
fair condition.
The large slashes in the barrier were sewed, and then two layers of
the Herculite plastic film were placed over the area with Herculite CVV
adhesive. The small tears were repaired in a similar manner. All compart-
ments were then inflated with an air compressor to check for leaks (Figure
19); the minor leaks found in this manner were also repaired.
The barrier was then swept clean in preparation for repackaging.
Starting with a 10-in. fold, the barrier was folded by a team of 6 to 8
people (Figures 20 and 21). When completely folded, it was tied with line
every 4 or 5 ft (Figure 22) and then placed on a pallet with the aid of a
forklift truck. On October 10, 1977, the barrier and the entire support
system were shipped to the USEPA's Edison, NJ facility to be available for
further tests.
35
-------
Figure 18. Air test of HMB after repairs.
v--
Figure 19. Start of folding HMB.
36
-------
5*s^^^v^-^%3fe<; . T-,.-X_.V
*->?*v ,£.*^-'-,:>r" '^SwSwfcc.-*.«-"- .'•"saSsi
Figure 20. Folding of HMB almost completed.
Figure 21. HMB folded and tied every 4 to 5 ft.
37
-------
APPENDIX
CURRENT VELOCITY MEASUREMENTS
This appendix summarizes the procedures used and the results obtained
from current monitoring tests during the 1976 trials, while the hazardous
materials barrier was being deployed and studied for its performance in the
field.
Measurements of current velocity were made on June 30 and July 1
and 2, 1976, during both flood and ebb tides, to determine the effects of
the tidal currents on the configuration and integrity of the HMB. Continu-
ous current monitoring was conducted with an in-situ recording current
meter; vertical profile data were collected at predetermined stations
during various portions of the tidal cycle.
Current velocities were measured at a single depth using an in-situ
film recording current meter installed sequentially at two stations
(Stations #1 and #2) adjacent to the HMB. (See Figure 23 for station
locations.) Recordings were taken at Station #1 from 1100 hr on June 30
through 1030 hr on July 1. The meter was then moved to Station #2 where
recording began at 1100 hr on July 1 and continued through 0900 hr on
July 2. In both cases, the meter was installed 12 ft off the lagoon
bottom. Water depth at Station #1 was 24 ft and at Station #2, 18 ft.
Station #1 was selected so that currents unaffected by the presence of
the HMB could be measured during both flood and ebb tide. It was located
approximately 40 ft from the east side of the barrier. Station #2, located
about 50 ft south of the barrier, was selected to measure the strength of
the ebb current. At this location, it also provided accurate measurements
of the actual current affecting the barrier, which was directly upstream
during the ebb tide cycle. It was suspected that the maximum ebb currents
would be stronger than the maximum flood currents. It was known that the
duration of the ebb cycle was much longer than the flood cycle. This was
confirmed by the data. The data from the in-situ current meter appear in
Tables A-l and A-2 for Stations #1 and #2, respectively.
In addition to collecting in-situ current data at a single depth,
current velocity profiles were also made at Stations #1 and #2 to determine
the relationship between speeds at a single depth and those throughout the
water column. The vertical profiling data were obtained using a surface
readout meter with a Bendix BIO ducted impeller sensor. Measurements were
taken at depths of 15, 10, 5, and 2 ft.
The vertical profiles at Station #1 were only obtained during three
38
-------
closely spaced time intervals on June 30. These data, tabulated in Table
A-3, confirm that current velocities at the surface are considerably higher
than those at the bottom of the lagoon. The vertical profile data at
Station #2 were taken on July 1, 1976. These data are reported in tabular
form in Table A-4.
The current conditions encountered at the test site should be
considered typical for major rivers and estuarine areas where a hazardous
material might be spilled. The vertical profiles show current speeds
considerably higher at the surface than at the bottom. At the surface,
current velocities were frequently recorded in excess of 1.5 knots; bottom
velocities were below 0.2 knot on most occasions. The HMB appears to hold
its configuration well in current speeds below 0.4 knot. When speeds exceed
0.4 knot, the forces on the barrier increase and there is a tendency for the
barrier to collapse, particularly at the surface. Collapse is, of course,
less likely on the bottom due to both the anchoring and the substantially
lower current velocities.
In areas of limited tidal height variations, the barrier can be very
effective at current speeds below 0.4 knot. When deployed in locales with
high tidal range, the HMB's effectiveness decreases as an inverse function
of the increase in tide range. With each tide cycle, flushing of a certain
percentage of the contained volume of water within the HMB was observed.
Under the conditions of this test, it was virtually impossible to separate
the effects of tidal flushing from those attributable to loss in general
integrity of the barrier.
39
-------
10
c
o
•1—
4->
IB
4-»
00
0)
s_
2
-------
TABLE A-1. IN-SITU CURRENT DATA FOR STATION 1
Time
Speed
(knots)
Time
Speed
(knots)
Speed
( Ki'lO"CS
1100
1115
1130
1145
1200
1215
1230
1245
1300
1315
1330
1345
1400
1415
1430
1445
1500
1515
0015
0030
0045
0100
0115
0130
0145
0200
0215
0230
0245
0300
0315
0330
0.17
0.10
0.08
0.04
0.07
0.05
0.02
0.08
0.14
0.13
0.18
0.20
0.28
0.14
0.24
0.27
0.26
0.24
0.05
0.05
0.00
0.07
0.12
0.07
0.13
0.16
0.08
0.14
0.20
0.19
0.25
0.22
June 30. 1976
1530
1545
1600
1615
1630
1645
1700
1715
1730
1745
1800
1815
1830
1845
1900
1915
1930
1945
July 1,
0345
0400
0415
0430
0445
0500
0515
0530
0545
0600
0615
0630
0645
0700
0.22
0.28
0.23
0.19
0.20
0.19
0.17
0.19
0.16
0.10
0.01
0.00
0.00
0.03
0.00
0.01
0.22
0.24
1976
0.22
0.25
0.21
0.21
0.25
0.23
0.25
0.22
0.20
0.21
0.17
0.10
0.05
0.01
2000
2015
2030
2045
2100
2115
2130
2145
2200
2215
2230.
2245
2300
2315
2330
2345
2400
0715
0730
0745
0800
0815
0830
0845
0900
0915
0930
0945
1000
1015
1030
0.21
0.24
0.28
0.24
0.20
0.19
0.18
0.15
0.16
0.13
0.13
0.09
0.08
0.05
0.11
0.12
0.08
0.02
0.04
0.05
0.03
0.12
0.24
0.19
0.17
0.22
0.17
0.18
0.13
0.11
0.09
41
-------
TABLE A-2. IN-SITU CURRENT DATA FOR STATION 2
Time
Speed
(knots)
Soeed
(knots;
Time
\ k i "i o t s i
1100
1115
1130
1145
1200
1215
1230
1245
1300
1315
1330
1345
1400
1415
1430
1445
1500
1515
0015
0030
0045
0100
0115
0130
0145
0200
0215
0230
0245
0300
0.08
0.09
0.10
0.10
0.09
0.10
0.10
0.06
0.05
0.03
0.05
0.10
0.13
0.13
0.13
0.15
0.11
0.14
0.07
0.04
0.07
0.10
0.05
0.05
0.09
0.10
0.12
0.12
0.14
0.21
July 1, 1976
1530
1545
1600
1615
1630
1645 's
1700
1715- ^
1730
1745
1800
1815
1830
1845
1900
1915
1930
1945
July 2,
0315
0330
0345
0400
0415
0430
0445
0500
0515
0530
0545
0600
0.19
0.14
0.15
0.18
0.22
•' 0.24
0.14
0.16
0.15
0.11
0.09
0.12
0.05
0.04
0.01
0.05
0.05
0.04
1976
0.20
0.20
0.25
0.25
0.23
0.20
0.19
0.25
0.18
0.18
0.17
0.14
2000
2015
2030
2045
2100
2115
2130
2145
2200
2215
2230
2245
2300
2315
2330
2345
2400
0615
0630
0645
0700
0715
0730
0745
0800
0815
0830
0845
0900
0.00
0.01
0.00
0.04
0.04
0.04
0.05
0.05
0.18
0.05
0.12
0.01
0.01
0.01
0.01
0.01
0.08
0.05
0.09
0.05
0.05
0.02
0.02
0.04
0.01
0.05
0.01
0.01
0.02
42
-------
TABLE A-3. VERTICAL CURRENT PROFILES
FOR STATION #1
Time
(hr)
1400
1410
1420
JUMc jU , i i/ / O
Depth
(ft)
-2
-5
-10
-13
-15
Bottom
-2
.-5
-8
-10
-15
-20
-22
-2
-5
-10
-15
-20
Current
(knots)
1.30
0.50 - 0.80
0.46 - 0.48
0.18 - 0.30
0.22 - 0.28
0.20
1.30
0.75
0.65 - 0.80
0.50 - 0.70
0.30 - 0.55
0.30 - 0.50
0.60 - 0.70
1.25
1.00
0.50
0.20
0.10
43
-------
TABLE A-4. VERTICAL CURRENT PROFILES - STATION 2
"Htm*
Time
(hr)
1245
1315
1324
1326
1331
1338
1340
Depth
(ft)
-2
-5
-10
-15
-2
-5
-10
-15
-17
-2
-5
-10
-15
-17
-2
-5
-10
-15
-2
-5
-10
-15
-17
-1
-2
-5
-10
-15
-17
-1
-2
-5
-10
-15
-17
'.-i -' ' ^/ ' > ' -' •" "-'
Current Time
(knots) (hr)
0.2 1345
0.1
0.1
0.05
0.15
0.0
0.0 1350
0.0
0.15
0.4
0.1
0.0
0.0 1355
0.0
0.4
0.05
0.05
0.1
1400
0.45
0.3
0.1
0.1
0.025
0.6 1405
0.5
0.45
0.2
0.1
0.1
0.75 1420
0.6
0.35
0.2
0.15
0.1
Death
(ft)
-1
-2
-5
-10
-15
-17
-1
-2
-5
-10
-15
-17
-1
-2
-5
-10
-15
-17
-1
-2
-5
-10
-15
-17
-1
-2
-5
-10
-15
-17
-1
-2
-5
-10
-15
-17
Current
(knots)
0.65
0.5
0.5
0.4
0.3
0.25
0.8
0.68
0.56
0.32
0.22
0.18
0.88
0.75
0.52
0.36
0.12
0.2
0.92
0.86
0.62
0.1
0.1
0.1
0.9
0.84
0.64
0.22
0.0
0.0
0.95
0.84
0.75
0.0
0.02
0.02
44
-------
Table A-4
(continued)
Time
(hr)
1430
1440*
1450
1455
1500
1505
1510
Depth
(ft)
_2
-5
-10
-15
-17
-1
-2
-5
-10
-15
-17
-2
-5
-10
-15
-17
-2
-5
-10
-15
-17
-2
-5
-10
-15
-17
-2
-5
-10
-15
-17
-2
-5
-10
-17
Current
(knots)
0.75
0.6
0.4
0.18
0.10
0.02
0.02
0.04
0.05
0.07
0.0
1.3
0.52
0.2
0.0
0.0
1.05
0.7
0.16
0.0
0.0
1.1
0.6
0.0
0.0
o.o
1.3
0.64
0.0
0.2
0.0
1.0
0.6
0.0
0.0
Time
(hr)
1515
1520
1525
1530
1540
1545
1555
Depth
(ft)
-2
-5
-10
-15
-17
-2
-5
-10
-15
-17
-2
-5
-10
-15
-17
-2
-5
-10
-15
-17
-2
-5
-10
-15
-17
-2
-5
-10
-15
-17
-2
-5
-10
-15
Current
(knots)
1.3
0.5
0.30
0.0
0.0
1.4
0.5
0.1
0.12
0.08
1.5
0.8
0.2
0.24
0.1
1.5
0.52
0.42
0.3
0.1
1.5
0.9
0.2
0.1
0.2
1.15
0.6
0.0
0.2
0.1
1.3
0.36
0.1
0.05
.
""me*-
45
-------
Table A-4
(continued)
Time
(hr)
1605
1615
1625
1630
"k^ r— n
Depth
(ft)
-2
-5
-10
. -15
-16
-2
-5
-10
-16
-2
-5
-10
-16
-2
-5
-10
-16
Current Time
(knots) (hr)
1.2 1635
0.6
0.1
0.1
0.1
1645
1.3
0.45
0.1
0.0
1655
1.6
0.76
0.28
0.0
1705
1.6
1.0
0.36
0.05
Depth
(ft)
-2
-5
-10
-16
-2
-5
-10
-16
-2
-5
-10
-16
-2
-5
-10
-16
Current
(knots)
1.55
0.8
0.26
0.08
1.6
0.67
0.2
0.17
1.6
0.5
0.0
0.2
1.5
0.56
0.21
0.18
* Wind came up; 15 to 20 knots.
46
------- |