EPA-R2-73-114
FEBRUARY 1973 Environmental Protection Technology S
Shore Termination for
Oil Spill Booms
Office of Research and Monitoring
U.S. Environmental Protection
Washington, DC 20450
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RESEARCH REPORTING SERIES
Research reports of the Office of, Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
degradation from point and non-point sources of
pollution. This work provides the new or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards.
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EPA-R2-73-114
February 1973
SHORE TERMINATION
FOR
OIL SPILL BOOMS
by
Archie C. Roberts
Project 15080 FVP
Project Officer:
Frank J. Freestone
Edison Water Quality Research Laboratories, NERC
Ediaon^ Kew Jersey 08817
Prepared for
OFFICE OF RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402
Price 50 cents domestic postpaid or 35 cents QPO Bookstore
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EPA Review Notice
This report has been reviewed by the Environmental Protection
Agency and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of
the Environmental Protection Agency, nor does mention of trade
names or commercial products constitute endorsement or recommenda-
tion for use.
ii
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ABSTRACT
SHORE TERMINATION FOR OIL SPILL BOOMS
One of the most common sources of failure in the application of floating
oil booms to contain an oil spill is leakage between the end of the boom
and the adjacent shoreline, deck or bulkhead. Booms cannot be fastened
solidly to the shore since they must rise and fall with the changes in
height due to tides and waves. The use of counter-currents generated
by a fire stream or prop wash is attractive, although it ties up a boat
often needed for other tasks. Furthermore, the shallow draft of a small
boat allows oil to escape beneath the boat unless the boat is overlapped
by the boom. Securing boom to the boat while avoiding the fouling of
the boat's propeller then become operational concerns.
This report describes a simple structure for mounting a small outboard
motor to "seal" the gap. This boom terminator can be constructed on-
scene with tools and materials generally available around the waterfront
by relatively unskilled personnel.
This report was submitted in partial fulfillment of Project 15080 FVP,
under the partial sponsorship of the Water Quality Office, Environmental
Protection Agency.
iii
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CONTENTS
Section Page
I Conclusions 1
II Introduction 3
III Background Study 5
IV Preliminary Design 7
V Final Design 11
VI Application 15
VII Acknowledgments 19
VIII References 21
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FIGURES
Number Page
1. Boom Terminator Construction Plan 13
2. Boom Terminator Applications - a. Diversion ^
Boom Terminator Applications - b. Collection 16
3. Terminator in Use 18
vi
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SECTION I
CONCLUSIONS
The use of prop wash to produce currents for herding and diverting oil
slicks is common practice. Such currents are useful in preventing the
spread of oil around the ends of boom where it is either impossible
or difficult to make an oil tight connection to the shore. The boom
terminator described above is one method of providing such a current
which makes it unnecessary to tie up a boat for this purpose. Except
for the need of occasionally refueling the engine, it also works
unattended. The construction materials should be readily available,
and the only expensive item is the outboard motor which, in this type of
emergency, could probably be borrowed for the spill duration. The
construction of the unit is well within the capabilities of the average
do-it-yourself carpenter. Because of the ease of construction, it is
unnecessary to maintain assembled terminators for an emergency. It is
only necessary to become familiar with the design and to stock the
materials.
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SECTION II
INTRODUCTION
A total boom system for controlling the spread and preventing the
escape of oil is only as good as its weakest component. If a
containment boom is used under sea conditions within its design
specification, the weak points often prove to be the boom ends and
ways must be found to seal the terminal gaps to maintain the
integrity of the total system. One problem normally encountered
is making an effective seal between the boom end and the shore. The
seal should have a good probability of being effective under the
majority of conditions encountered in those areas for which the
equipment is designed.
At certain stages of its research program on oil spill control, the
Marine Division of the Fire Department of the City of New York was
faced with the problem of providing an effective seal between the
boom used for test purposes and a bulkhead. The problem was easily
solved by using water streams from the fireboat to provide a counter-
current offsetting the normal water flow through the boom/bulkhead gap.
It was recognized that this solution to the problem was not universally
applicablicable, but the principle of blocking the normal flow through
the gap with a counter-current was considered to be a reasonable approach
to the problem, and this path was pursued in the subsequent investiga-
tion and design. The end product of the investigation is a design for
a dynamic boom terminator which can be used in most situations where
it becomes necessary to close off oil leaks around the ends of boom.
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SECTION III
BACKGROUND STUDY
In most harbors subject to oil spills, the shoreline characteristics
can vary from smooth vertical bulkheads to rough sloping riprap,
and each type presents its individual problems for boom termination.
The immediate shoreline of most harbors is found to be a result of
land fill and dock building activity, and the chances of finding a
smooth surface to provide a basis for a direct mechanical seal
between boom and shore are rare. The options open are to fair
out the surface to allow for a direct oil tight connection, or to
go to some type of dynamic device which does not require a tight
connection. One problem involved with riprap shorelines and the
general run of land fill areas is that irregularities and voids are
difficult to smooth out or fill. Often vertical bulkheads are faced
with timbers to protect the concrete or stone and therefore do not
provide a smooth profile.
In addition to the problems presented by the character of the shore-
line, the sea itself makes its contribution. Values of current, tide
and wave must be considered in determining the design criteria, and
the limiting values of each imposes restraints on the terminator
design. In this case, the values used were those likely to be en-
countered in New York Harbor and could be considered as fairly
representative of most ports in the United States.
Although currents in areas of New York Harbor often reach values in
excess of 5 knots, the terminator need only be as effective as the
boom itself, and analyses of fixed boom have shown that they will only
contain oil at currents of O.Tkiots^1' normal to their direction. The
design, therefore, was based on this lower figure. The design criteria
for tidal range and wave height were taken as 6 feet and 2 feet,
respectively.
Other types of boom termination were considered in addition to the use
of water streams:
1. Sliding mechanical oil tight seals for vertical bulkheads
2. Bubble barriers
The first type has limited use. Its primary application would be for
permanent oil terminal installations where an optimum design can be
made to fit the particular conditions. The advantage of a well-
engineered installation of this type is that it is completely passive
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and requires no power input. It was not considered applicable to a
situation where the shore/boom gap must be sealed off quickly for
various types of shore profiles. Bubble barriers are much more
universal and as a first order approximation their effectiveness is
not seriously modified by waves or tidal changes. Research data
indicates, however, that bubble barriers are only about one-half as
effective as solid barriers when trying to hold back oil against a
current. (See Reference [1]). Based on this background information,
it was decided to concentrate on designing a terminator which could
create a counter-current of sufficient velocity to counteract the
normal current.
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SECTION IV
PRELIMINARY DESIGN
During previous tests involving the herding of oil slicks for concentra-
tion and pick-up, two methods had been investigated: (1) Use of a
boat's prop wash and (2) use of hose and fire monitor streams. These
investigations indicated that, for herding, maneuvering the boat to
utilize prop wash was not practical considering the water pumping
capability of fireboats. For a boom terminator, however, the use of
an outboard motor to produce a counter-current with it s prop wash
seemed attractive when compared with the alternative of creating a self-
contained motor-water pump combination. The solution appeared to be in de-
signing a stable platform which would hold an outboard motor and its
gas tank, and orient it such that the prop wash was in the proper direction
to counteract currents tending to flow through the boom/shore gap.
The initial tests were made using the fireboat's small workboat as a
terminator. A section of oil spill boom was set out to form an U in
the test basin with a gap between one boom end and a vertical bulkhead.
A fireboat was moored further along the bulkhead and its monitor
streams were used to set up a 1-knot current in the gap. The small
boat, fitted with a 9-hp outboard, was placed in line with the boom,
with the stern moored to the bulkhead, and the oil "boom fastened and
overlapping the forward end of the boat on the upstream side. The
boom was set- rfith the boat angled at 40° to the bulkhead so that its
prop wash had a component opposing the current set up by the fireboat,
The gap was adjusted to 10 feet by adjusting the securing line, and the
motor started. Data processing cards were used as floaters to map the
surface current flow. With the motor running at standard throttle, none
of the cards penetrated the gap. The fan-shaped surface current set
up by the prop wash bent the prevailing current flow lines so that
those cards which would normally flow through the boom gap were deflected
outward and were caught behind the boom.
Maintaining the 1-knot current, the boom gap was progressively opened
to 15 and 20 feet. The data processing cards did not pass through with
the 15-foot gap, but some did manage to penetrate when the opening
was increased to 20 feet. Subsequent tests using a 5-hp motor
showed that it would seal a 10-foot gap with an occasional card
getting through at 15 feet. Based on these experiments and other
size/weight considerations, it was decided to purchase a 6-hp engine
for incorporation into the terminator design.
Some theoretical calculations based on the engine specifications were
made to substantiate the experimental results. The propeller area
was roughly 1/3 ft 2, its pitch 1/2 ft, and its speed 2400 rpm (40 rps ).
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Considering the propeller as a pump with perfect coupling, it should
produce a water flow of 6-2/3 ft /sec at an output velocity of 20 ft/sec.
This flow through a 1/3 ft area can be considered ideally to have
expanded into a 6-2/3 ft area by the time the velocity had decreased
to 1 ft/sec. This appears to be a reasonable area of surface current
intercept. The next objective was to design an inexpensive, easily built
terminator which would not require tying up the ship or its small boat,
since they are usually needed for other work during an oil spill.
It should be noted, however, that if a spare small boat is available it
could, with some adaptation, serve as a terminator. In an in-line
configuration the small boat does not have enough draft to be an effective
boom extension. The boom must, therefore, lap the boat and provisions
must be made to fasten the boom and boat together while maintaining the
boom integrity and assuring that the boom does not foul the propeller of
the outboard motor. In waves there may be relative motion between boat
and boom with subsequent chafing and boom damage.
In order to make a practical dynamic boom terminator, it must be built
from materials readily available on the waterfront if it is to be of any
use as an emergency piece of equipment. The structure for supporting the
outboard and its fuel tank' should also be made from inexpensive, readily
attainable materials, and be suitable for construction by relatively
inexperienced people, with a minimum of tools. The initial model of the
terminator only partially met these specifications. The basic con-
struction materials were plywood and a 55 gal. oil drum. The use of a
55 gal. drum for flotation at first glance appears to be a good choice
since drums are easily available and can provide adequate buoyancy. The
problems that arise are:
1. The stable flotation aspect is horizontal and it requires considerable
ballast to make it float upright while supporting an outboard motor.
2. Since the drum becomes part of the boom it has to be ballasted down
so that it has 2/3 of its 3 ft height submerged.
3. This type of buoy is a spar buoy, and is not surface-following for
short period waves. The natural undamped period for such a buoy is
1/2
Tn = 2TT (W/kg) '
For a simple spar buoy
k = W
k -s
Where W = the weight of the buoy in pounds, and d = the static vertical
displacement in water-due to this weight in ft and g = accleration of
gravity =32.2 ft/sec .
1/2
Tn = 2TT (d/g) =1.11 /d
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This calculation does not allow for end effects (added mass) on the drum
which would tend to increase the period. The drum, therefore, will not
follow short period waves.
4. The thin metal used in standard drums makes it impractical to weld
attachments to it. These attachments must, therefore, be strapped on,
making oil tight joints between the drum and the boom attachment plates
difficult.
5. The outboard motor weight cannot be centered with respect to the
buoyancy of the drum, and the ballast must be located so as to adjust the
trim as well as the depth of flotation.
6. The overall design did not meet the criterion that it could easily be
made by relatively inexperienced people. In addition to the wood work
involved, the motor and ballast mounting brackets were fabricated from
angle iron and required the services of a welder.
7. The finished terminator was heavy, weighing approximately 320 Ibs
without motor or fuel - the total rigged weight being about 380 Ibs. This
weight was too much for manhandling, and a small crane or davit was needed
to launch it from the fireboat.
Although once in the water this terminator performed well, and alternative
design was sought which would offset some of the disadvantages of the 55
gal. drum model and yet be able to support the outboard motor.
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SECTION V
FINAL DESIGN
In order to provide a lightweight unit with a shorter natural period than
the 55 gal. drum model, two criteria had to be met:
1. Considering the unit to be essentially a buoy, it must be of the
surface-following rather than spar buoy type.
2. The stability must be provided by the buoyancy configuration and not
by means of counterweights.
Both of these criteria are met by a raft. It is hard to tip over because
of the large correcting moment produced as a result of heel, and it follows
the surface because of the large areas crossing the air/water interface.
In the formula for natural period for vertical motion
1/2
Tn =2Tr(W/kg)
k (the equivalent spring coefficient which is a measure of the change in
vertical displacement as a function of a change in weight) is large when
the surface intercept area is large. By using low density flotation
material, W (the weight) becomes small. The ratio W/k in the formula
above, therefore, is decreased on both counts with a subsequent decrease
in the natural period.
Two types of lightweight flotation were available - rigid foam and in-
flatable floats. Since rigid flotation is not universally available,
and inflatables looked attractive from the storage point of view, the
latter was chosen for buoyancy.
Selected was a heavy duty inner tube for truck tires. The outboard can
be mounted with its shaft down through the center of the toroid formed
by the large tube. The system is therefore balanced, and there is no need
for large amounts of ballast to adjust the trim. Once this decision was
made, the design was simply one of mechanically tying the boom, the
flotation and outboard motor together. The resulting design is shown in
Fig. 1. Two sheets of 1/2" marine or exterior plywood are connected in
the shape of a V. A 2 x 12 timber is fastened across the V to serve as
a motor mount. Each sheet of plywood has two holes cut in it, through
which the tube can pass when it is inflated. In order to insert the tube,
1/2" slots extend vertically from the hole centers to the top of the ply-
wood. The tube is slipped down through the slot while deflated, and then
pumped up to fill the hole. The oil spill boom is sealed to the apex of
the V and a split bridle is fastened at the open end for making the
on-shore attachment.
Two versions of this terminator were made. The first was a rigid model
11
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made to test out the design, while the second was a unit capable of
being easily knocked down for stowage. Because the former is easier
to construct and needs fewer purchased parts, it will be described
in detail rather than the latter:
With reference to Fig. 1, the materials needed for construction are
1. 1 each 4' x 81 sheet of 1/2" marine or exterior plywood
2. 3 ft length of 2" x 12" (wood)
3. 30" length of 2" x 4" (wood)
4. 1 each 1000-20 truck tire tube
5. 1 each 1" dia by 36" hardwood dowel
6. 2 each 1" hose clamps
7. A supply of galvanized nails.
Although it is possible to build the unit with hand tools, use of a
table saw and a saber saw would simplify the job.
The 1/2" plywood sheet will make the two sides plus the oil boom
attachment strip. The edges of the 2" x 12" are ripped at 18° angles
to fit as the motor mount bracket, and the two thin wedges cut off
are used to fair the sides into the boom attachment strip. The 2" x
4" spreader at the open end of the V is also cut at an 18° angle.
Dimensions for the cutouts in the side panels are shown in Fig. 1.
The 1/2" slots which allow the deflated tube to be slipped down into
position can be reclosed by tacking on 1/4" plywood battens. Be sure
the sharp and ragged edges made by the saw while cutting the 11" hole
are rounded off in order to prevent chafing of the tube. It should
be noted that the actual shape of the hole formed by the intersection
of the tube and plywood is a distorted ellipse. The tube will, however,
conform to the circle and the layout work is thus simplified. The unit
can be assembled with bolts, screws, or galvanzied nails - with nailing
being the quickest and simplets method. A notch is cut in the top of
each side panel to hold the 1" dowel, which in turn, is clamped to the
gas tank handle with the hose clamps.
Two 3/4" holes are drilled in the plywood at the open end of the V
for fastening a 2-part mooring bridle. These holes are positioned at
the waterline for 1/2 tank fuel conditions. Thus, if the mooring
line is fastened ashore at a height of mean tide, it produces the least
possible vertical component tending to lift or submerge the unit as the
tide changes. The plywood strip at the apex of the V can be drilled on
site to match the end fittings of the particular boom being used. Make
sure that the fastenings between the strip and the side panels are
distributed proportionally to the in-line loads expected to be trans-
mitted at each point of boom attachment. This applies particularly to
points where wire rope or chain stress members are tied in.
12
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USE WEDGES TRIMMED
FROM 2" x 12"
PART
I
2
3
4
MATERIAL
'/2 PLYWOOD
'/2 PLYWOOD
2"xl2"
2"x4"
^DIA. FOR BRIDLE
FIGURE I
BOOM TERMINATOR CONSTRUCTION PLAN
13
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SECTION VI
APPLICATION
Oil spill booms are used in two manners:
1. To divert a moving oil slick and carry it away from an area
which needs to be protected;
2. To prevent the spreading of oil and thicken it up for subsequent
skimming operations.
Fig. 2 indicates how the terminator can be used under both conditions.
In both configurations, the terminator is producing a current which is
opposite the direction of oil flow, and acting as an extension of the
boom.
15
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TERMINATOR
DIRECTION OF
NORMAL CURRENT
AND OIL FLOW
DIVERSION
AREA BEING PROTECTED
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TERMINATOR
SKIMMING
AREA
COLLECTION
BOOM
FIGURES 2a-2b
TERMINATOR APPLICATIONS
16
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Figure 3
Boom Terminator in Use
17
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SECTION VII
ACKNOWLEDGMENTS
The field testing necessary for the development of the dynamic Shore
Termination for Oil Spill Booms, as described herein, was done by
Alpine Geophysical Associates, Inc. with the full cooperation of
the Officers and Members of the Marine Division of the New York
City Fire Department.
The guidance of Mr. Howard Lamp'l, EPA Project Officer, and the
cooperation of the City of New York and the U. S. Navy in providing
the test basin at Wallabout Creek, Brooklyn, New York, is gratefully
acknowledged.
19
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SECTION VIII
REFERENCES
1. Milz, E. A., "An Evaluation of Oil Spill Control Equipment and
Techniques", A.P.I.'s Division of Transportation Pipeline
Conference, Dallas, 1970.
4 U. S. GOVERNMENT PRINTING OFFICE : 1973—514-153/220
21
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
1. Report No.
w
4. Title
SHORE TERMINATION FOR OIL SPILL BOOMS
7. Author(s)
Roberts, Archie C.
9. Organization Alplne Geophysical Associates, Inc.
under contract to
New York City Fire Department
5. R, irtD. 2
6.
8. Performs : Orgar -ation
Revolt Nc.
15080 FVP
13. Type c ' Repoi :nd
Period Covered
2* Sponsoring Organization
n. Supplementary Notes
Environmental Protection Agency, W.Q.O.
Environmental Protection Agency report
number, EPA-R2-73-114, February 1973.
16. Abstract
One of the most common sources of failure in the application of floating oil booms to
contain an oil spill is leakage between the end of the boom and the adjacent shoreline,
deck Qt bulkhead. Booms cannot be fastened solidly to the shore since they must rise
and fall with the changes in height due to tides and waves. The use of counter-
currents generated by a fire stream or prop wash is attractive, although it ties up a
boat often needed for other tasks. Furthermore, the shallow draft of a small boat
allows oil to escape beneath the boat unless the boat is overlapped by the boom.
Securing boom to the boat while avoiding the fouling of the boat's propeller then
becomes operational concerns.
This report describes a simple structure for mounting a small outboard motor to "seal"
the gap. This boom terminator can be constructed on-scene with tools and materials
generally available around the waterfront by relatively unskilled personnel.
This report was submitted in partial fulfillment of Project 15080 FVP, under the
partial sponsorship of the Water Quality Office, Environmental Protection Agency.
17a. Descriptors
17b. Identifiers
Oil Spills, Harbors, Hydrodynamics, Riprap
* *
Containment Boom Terminator, Oil Seal, Boom Terminal Gap,
Construction Details
17c. COWRR Field & Group
05D
18. Availability
(JK»port)
<
20. Security Class,
(Page)
21.
Pages
22. Price
21
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D. C. 2O24O
Abstractor Archie C. Roberta
I "•*• ' —-
| Institution Alpine Gonphyo-f cal Aaaoc. Ing,
WRS1C IO2 (REV JUNE 1971)
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