WATKH I'OLI.l'TlON CONTROL RESEARCH SERIES 15080DOZ12
!/7l
TESTING AND EVALUATION
OF OIL SPILL RECOVERY EQUIPMENT
ENVIRONMKNTAL PROTECTION AGENCY WATER QUALITY OFFICE
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WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Reports describe
the results and progress in the control and abatement of
pollution of our Nation's Waters. They provide a central
source of information on the research, development and
demonstration activities of the Environmental Protection
Agency, Water Quality Office, through in-house research
and grants and contracts with Federal, State and local
agencies, research institutions, and industrial organizations.
A triplicate abstract card sheet is included in the report
to facilitate information retrieval. Space is provided on
the card for the user's accession number and for additional
uniterms.
Inquiries pertaining to Water Pollution Control Research
Reports should be directed to the Head, Projects Reports
System, Planning and Resources Office, Office of Research
and Development, Environmental Protection Agency, Water
Quality Office, Room 1108, Washington, D. C. 202^2.
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TESTING AND EVALUATION
OF
OIL SPILL RECOVER! EQUIPMENT
Main Port Authority
Maine State Pier
Portland, Maine 04111
for the
WATER QUALITY OFFICE
ENVIRONMENTAL PROTECTION AGENCY
Program Number 15080 DOZ
December, 1970
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402 - Price $1.50
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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 Pro-
tection Agency, nor does mention of
trade names or commercial products
constitute endorsement or recommenda-
tion for use.
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ABSTRACT
This report summarizes results of a project for testing
and evaluating representative samples of oil spill control
equipment. It presents a detailed analysis of the cap-
abilities and limitations of all equipment tested
together with recommendations for further developments.
Suggestions for various techniques for deployment and
operation of the equipment under varying ocean conditions
are included.
The report is directed toward mechanical means for
removing spilled oil from harbors and adjacent waters
and an Appendix described results obtained under con-
ditions of 30K winds and 8' waves in the Gulf of Mexico
in March, 1970.
Tests reported include evaluations of mechanical booms,
air barriers, 5 types of skimmers and several alternative
arrangements of oil recovery and disposal systems. A
design for an articulated skimmer adaptable to rough
water operations is included.
Appendices to the report offer suggestions on effective
measures for enlisting community support for oil pre-
vention and clean-up programs.
The report urges industry to take the initiative to
provide complete integrated systems for oil spill clean-
up operations under both controlled and emergency
conditions and available for use in all portions of the
ocean.
This report was submitted in fulfillment of Contract
15080 DOZ between the Federal Water Quality Adminis-
tration and the Maine Port Authority of Portland, Maine.
Key Words:
Curtain Booms
Fence Booms
Air Barriers
Oil/Water Mix
Skimmers
Throughput Capacity
Oil/Water Separation
Rate-of-rise
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TABLE OF CONTENTS
Section Title Page
I. Summary of Conclusions and Recommendations 1.
II. Preparation for the Testing Program 9.
III. Mechanical Booms 17.
IV. Air Barriers 37.
V. Skimmers 47.
VI. Reclamation and Disposal Equipment 57.
VII. The "Systems" Approach 63.
Acknowledgments 71.
B ib1iogr aphy 73.
Appendices
A. Special Projects Developed in the
Testing Program 77.
B. The Louisiana Spill, February/March, 1970 87.
C. Oil Spill on Bounding Bay, (A Narrative) 97.
D. Community Response to the Oil Clean-up
Problem 117.
E. A Clean-up System for Major Oil Spills 127.
F. Aerial Photography of Oil Spills -
Singco Corp. 133.
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LIST OF EXHIBITS
No. Page
1. Core Samples of an Oil Spill 137.
2. Forces Acting in an Oil Spill 138.
3. Typical Boom Designs 139.
4. Standard Towing Procedure 140.
5. Current Patterns Under a Fence Boom 141.
6. Moving Oil Inside a Boom 142.
7. Towing a Funnel Boom 143.
8. Diversion Boom Test 144.
9. Current Velocities Near an Air Barrier 145.
10. Vertical Currents Generated by Air Barrier 146.
11. Demonstration of Barrier Effect of Air Bubbles 147.
12. AK Skimmer Design 148.
13. Skimmer Boat Design 149.
14. 22 Skimmer Designs Studied in Project 150.
15. Articulated Skimmer 151.
16. Effect of Oil Thickness on Efficiency of a Weir 152.
Skimmer
17. Alternate Systems for Recovery, Reclamation and 153.
Disposal
18. Separating Tanks 154.
19. Floating Tank 155.
20. Floating Tank (Continued) 156.
21. Aerial Observation Procedure 157.
22. Oil Pollution Warning Poster 158.
23. System Test - Funnel Boom 159.
24. Towing Technique - Funnel Boom 160.
25. Effect of Wind or Current on Funnel Boom 160.
26. Effect of Air Barrier Currents on a Wind-Driven 161.
Spill
27. Samples of Aerial Photo Techniques - Singco Corp.162.
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SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS
The basic objectives of Project 15080 DOZ have been
accomplished.
1. Commercial equipment for oil spill clean-up has
been tested and evaluated to determine its cap-
abilities and limitations.
2. Two designs of experimental Air Barrier equipment
have been tested.
3. A working model of a rough water skimmer has been
built and tested to determine the practicality of
its design.
4. Broad specifications for an equipment system for
major oil spills have been outlined.
In addition to those required tasks, several other ac-
complishments have resulted.
1. Modifications to existing oil spill equipment have
been suggested to manufacturers. In many cases
these have been adopted and incorporated in the
new models.
2. Techniques developed during the testing program
contributed substantially to the successful clean-
up of the Louisiana oil spill in February and March
of 1970.
3. The equipment industry has been made aware of some
basic engineering concepts in the design and
operation of spill clean-up equipment. They relate
to
a. Limitations to the containment capacity of a
boom.
b. The need for very slow relative speed of boom
and oil slick in containment operations.
c. Importance of rate-of-rise factor in designing
clean-up equipment.
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4. A procedure for aerial reporting of oil spills has
been announced by District 1 (Boston) of the U.S.
Coast Guard. (Described in detail in Annual Report
of this project dated October 30, 1969.)
Conclusions and Recommendations derived from evaluation
tests, observations, practical experience and studies
are summarized below and are detailed in the appropriate
sections of the report.
MECHANICAL BARRIERS
Conclusions
1. The use of a boom to control the movement of an oil
slick can accomplish these tasks:
a. If complete encirclement is possible the boom
can
1) Prevent further spread of the slick, and
2) It can contain a large amount of oil -
up to at least 2" of film thickness - as
long as wind and wave permit.
b. As a barrier across the path of a spill, a
boom can
1) Delay passage of the slick until depth of
oil pool against the arc of the boom
approaches two-thirds of the draft of the
boom, or
2) Until current and turbulence pull oil under
the boom.
c. Used as a sweep or trawl, the boom can
1) Gather pools of surface oil in the arc of
the boom so that skimming operations can
be effective in those areas.
2) Compact widely scattered puddles of oil
or very thin films so that the efficiency
of skimming can be improved.
3) Tow or pull limited areas of slick from
one location to another to avoid sensitive
areas or to reach fixed oil-removal
installations.
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d. Used as a means of guiding the flow of an oil
slick, the boom can
1) Divert the flow of a spill by as much as
20 from its natural path.
2) Lead a slick to the area where skimmer
equipment is operating.
3) Limit the spread of a flowing spill in the
area near the source.
2. For use in rough water, a minimum of 12" of freeboard
is essential to reduce over-flow by surface waves and
wind-driven spray.
3. Present designs can be effective when operated by
trained personnel, but continued development of
accessories and easier handling techniques are needed.
4. The overall evaluation of various styles of mechanical
booms suggests that
a. The curtain booms can be effective in shallow
water and calm wind and wave conditions. As
such, they offer very good cost effectiveness
in protected waters.
b. The light fence types offer the greatest pro-
tection and versatility for most situations,
though their effectiveness may be very limited
in shallow waters. (Less than 2 feet.)
c. The heavy fence types are handicapped by heavy
weight, and the need for mechanized handling
equipment but their extra freeboard and
stability can be very valuable in rough water
conditions.
Recommendations
The following items should be considered by any supplier
or manufacturers of boom equipment:
1. Improve the part that the boom can play in a complete
clean-up system by
a. Making it compatible with other equipment.
b. Making it compatible with other booms.
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c. Increase the ease of launching and recovery
from a work boat or dock,
d. Design the boom to assist the clean-up operation
- whether by skimmer, chemical or other device.
Improve its ability to exert more force against an
oil spill.
a. Consider the addition of air or water jets to
augment its abilities as an inert barrier.
b. Consider the aerodynamic possibilities of the
freeboard structure as an assist in rough water.
Explore the use of multiple booms, with a secondary
structure to act as
a. A channel to pick up small patches of oil which
may get past the primary structure.
b. An auxiliary structure to act as a wave damper
in choppy water.
Designers should explore the use of a material to
limit the accumulation of marine growth on a boom,
and should provide a method for cleaning such growth
from a boom.
More attention needed on leak-proof fastening of
booms to docks, boats and skimmers.
AIR BARRIERS
Conclusions
Air Barriers hold real promise for fixed installations
across slips and parallel to unloading docks, for
a. Continuous stand-by operation at reduced air
pressures should keep the hose ready for instant
use, with maximum air pressure to be used only
in emergencies.
b. The Air Barrier generates its strongest
horizontal forces at or near the surface of
the water. Vertical forces are also present,
but their effect on oil spills needs additional
research.
c. The sub-surface air curtain can partially divert
sub-surface tidal currents of low velocity.
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d. An air barrier can be almost as mobile as a
mechanical barrier. Compressors, buoys and
other accessories for operating an air barrier
can be ship-mounted without undue difficulty.
e. The Air Barrier's ability to contain or divert
oil in rough water has been tested by the manu-
facturer but results have not yet been published,
2. Some models should be sufficiently versatile to operate
in several different applications.
We realize fully that a general purpose model might
entail a compromise with some engineering refinements
which could be realized if the barrier were engineered
for a specific task.
3. The Air Barrier may perform effectively in rough water
conditions where the full force of surface waves and
wind would not be exerted against the air supply pipe
suspended sub-surface.
4. An Air Barrier used to surround a ship at a pier or
at a single-point-mooring has some potential economic
advantages as follows:
a. Moderate installation costs
b. Minimum manpower to activate and monitor its
performance
c. Will not limit the access of supply and work
boats to the tanker
d. Not susceptible to accumulation of ice in
freezing weather
Recommendations for Further Testing and Development
1. The potential for permanent installations should be
researched in more detail because of
a. Possibility of low installation costs and low
upkeep
b. Possibility of using an air source which could
be inter-changeable with other productive work
when the air barrier is not required
c. The barrier can be quickly and effectively
activated by one man when needed
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2. The potential of a mobile air barrier should be
explored.
3. Rough water performance needs further research and
demonstration.
SKIMMERS
Conclusions
1. Improved skimmer designs are needed:
a. For rough water operations
b. For high-speed pick-up of thin oil slicks
spread over wide areas.
2. For massive oil spills, a through-put of 500 gpm
or more is needed.
3. Most versatile design at time of this report seems
to be the circular sump with a fixed or adjustable
weir.
4. The endless belt "separating" skimmers have good
potential for small spills in protected waters.
5. Dependable pumps, motors and accessories are
essential for good skimming operations.
6. The skimming process, by itself, will not generate
a surface flow of oil for any great distance. 6'
to 10' seems to be the maximum at present.
7. The skimmers must go to the oil, or the oil must
be brought to the skimmers.
8. Skimmers should have a high degree of compatibility
with all other units in the system.
Recommendat ions
1. The development of improved skimmer designs should
be accelerated until there is high volume capacity
at strategic points near all petroleum centers.
2. One major objective is the skimming of massive spills
in rough water conditions.
3. Another objective is the skimming of very thin slicks
spread over wide areas.
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4. Optimum performance toward these two separate
objectives may require the use of dis-similar
skimming principles.
RECLAMATION AND DISPOSAL EQUIPMENT
Conclusions
1. In any system of oil recovery and disposal, primary
separation of the oil from the water should be intro-
duced as early in the system as possible so that the
problem of handling large volumes of oil/water mix is
minimized.
2. Under most conditions, and with most types of oil,
the gravity separation system is so simple and
dependable that it should be given first consideration.
3. When and if shipboard separators (such as centri-
fuges or other techniques become available), such
equipment should be introduced into the system at
the earliest possible point to reduce the volume
of liquid to be handled.
Recommendations
1. The ultimate objective of the recovery and disposal
system should be to deliver the largest possible
quantity of reclaimable oil to an oil refinery which
can receive it.
2. The use of high pressure and high efficiency oil
burners should be explored as a method of ultimate
disposal of non-reelaimable oil sludges.
3. At the present state of the art, the design and
operation of equipment to receive oil from the
skimmer pumps and to handle it through ultimate
disposal will depend on the type of equipment which
is available at or near the location of the spill.
In most areas where oil is being handled or trans-
ported in any volume, there is probably an adequate
inventory of pumps, piping equipment, valves, tanks,
and other accessories which can be mounted on surface
craft or assembled at strategic shoreside locations so
that systems such as described above or variations
of them can be put together and operated effectively.
4. It is suggested that attention be given by government
and industry to providing specially designed shore-
side separator units. Vessels carrying petroleum
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products could then tie up at place of loading and
discharge the remaining ballast into separator tanks
rather than discharging ballast into the sea. These
units would be strategically placed at loading points.
(Note: This type of installation was called for
in a Presidential message delivered on May 20,
1970.)
A CLEAN-UP SYSTEM FOR MAJOR OIL SPILLS
Conclusions
1. The type of equipment described has been proved to
be effective up to the limits specified.
2. Basic clean-up systems built around the equipment
specified would constitute effective systems to the
limit of their capacities. (Equipment should include
both weir skimmers and belt or disc skimmers.)
3. Individual systems, as described, would provide
effective clean-up capacity, adequate for many
locations where small spills might occur.
4. High mobility of the individual systems would permit
quick concentration of multiple units to combat
massive spills.
Recommendations
1. Pending the development of major advances in technology,
units as described should be placed at strategic
locations throughout the United States.
2. Action should be initiated to install such units
(or the essential elements thereof) on all tankers
operating on routes where land based equipment is
not close at hand.
COMMUNITY RESPONSE TO THE OIL SPILL CLEAN-UP PROBLEM
Conclusions
A well organized community group, dedicated to the pre-
vention of oil spills always and to immediate and effective
clean-up of oil spills when they do occur, is the best
guarantee of continued progress in the controlling of oil
pollution on navigable waters.
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PREPARATION FOR THE TESTING PROGRAM
Review of the State of the Art
Early in 1969 a literature review was initiated to develop
background material on oil spill control technology.
Coverage of the subject at that time was found to be
sparse and few comprehensive reports were available. The
review of literature has continued steadily throughout the
project so that today there are many more reports on the
major spills, technology for using equipment and studies
of various aspects of oil spill phenomena. Universities,
government agencies in the United States and Abroad, the
petroleum industry and equipment suppliers have become
major sources of information on the subject and an in-
creasing amount of valuable data has been collected in
our files. (See Bibliography)
In addition to the continuing search of literature,
personnel attended meetings and conferences on many
aspects of the problem and maintained contact with many
groups and individuals who had experience with practical
operations. Locally, these included Coast Guard personnel,
members of the Maine Port Authority, Portland and South
Portland Fire Departments, local marine contractors and
barge and tanker operators.
On a broader front, personnel have attended a series of
demonstrations and conferences by suppliers of equipment
and materials and by local or regional groups engaged in
organizing and operating oil spill prevention and control
programs. The FWQA has been- a continuing source of
information and has supplied several documents relating
to major oil spills and to equipment and procedures for
combatting them.
A review of the information which was available from all
sources indicated that there was very little definite
knowledge on many phases of the testing program and there
were no generally accepted standards against which equip-
ment could be evaluated.
Technology for making comparative tests of equipment
designs was almost non-existent.
The forces which are active in an oil spill had not been
catalogued in a comprehensive manner and the few scien-
tific treatises which were available presented very little
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information which could readily be used by lay personnel.
Consequently, it was necessary for the project to design
its own testing laboratory, develop necessary techniques
of testing procedures in order to arrive at definite
evaluations and conduct additional research into all
phases of the oil spill cycle from initial overflow to
final clean-up.
Equipping a Testing Laboratory
Operations planned required a test site having very
special facilities. An area was leased in South Portland,
Maine in a space which had previously been used for building
and launching Liberty ships. Two ship launching basins
800' long by 80' wide were available with adequate parking
and storage space alongside. The testing area was ideal
for controlled experiments in smooth water conditions and
it provided an effective base for observation and evalu-
ation of testing procedures.
The area was large enough to maneuver boats and the
floating equipment used in oil spill control work. The
tidal testing basin was protected from violent winds under
most conditions but occasional northerly winds provided
wave conditions up to 4' inside the enclosed basin. Tides
measured 9' to 12' in height and tidal currents adjacent
to the testing basin approached IK in velocity.
On-shore storage facilities were adequate and observation
platforms adjacent the area provided sufficient height
for good viewing of testing procedures and good camera
angles.
Water in the testing basin was generally clean which
permitted limited sub-surface observation without the need
for sophisticated underwater technology or specially built
viewing chambers. There was adequate access to the
testing basin for the power boats and other floating
vessels and equipment which were used in the program.
The basin was surrounded on 3 sides with solid cement
docks so that oil spills could be created and cleaned up
without the danger of spreading pollution to nearby shore-
lines.
Rough water conditions were conveniently available in
Portland Harbor near the testing area and large ground
swells and a wide variety of surface conditions were
available just outside Portland Harbor about 2 miles
from the testing area.
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The testing area was enclosed by a cyclone fence patrolled
by industrial security personnel of the lessor.
The basic items of floating equipment for laboratory use
included a small wooden barge (I2lx22l) to serve as a
work platform, a 16' work boat powered with a 15 H.P.
outboard motor, a specially built floating platform on
which a variety of instruments could be mounted and a
floating fabric tank of 5,000 gallon capacity which was
used for temporary storage and transportation of oil and
water taken from the ocean during the clean-up tests.
Dockside equipment included a field office and an oil/
water separating system of 2,000 gallon capacity.
The field office provided shelter and work space for
personnel during the winter months and served as a store
room for marine gear and equipment necessary to support
the operation.
The oil/water separation system included two steel oil
tanks, each of 1,000 gallon capacity, and fitted with a
series of valves to provide selected drainage of oil and
water levels.
Sixteen hundred feet of air barrier hose was purchased
and installed in various configurations around the basin
both for testing purposes and as a barrier to prevent oil
spilled in the basin from flowing out into the ocean.
Details of the operation of the equipment described above
will be found in following sections of this report.
Development of Testing Technology
The project moved into its testing area in March of 1969
and proceeded with the development of some basic technology
for measuring the effectiveness of oil spill equipment.
Measurement of Ocean Currents
It was found immediately that there was no marine speed-
ometer equipment available for accurate measurement of
surface and sub-surface currents at the low velocities
which would be encountered in the program. Suitable
instrumentation was developed by modifying new designs
of marine speedometers which were just coming on the
market. The equipment uses strain gauges activated by
a probe which can be positioned at the point on the
surface of the water or below the surface where the
reading should be taken. Reactions of the strain gauge
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are transmitted through a modified Wheatstone bridge
circuit to a battery powered amplifier and the output
can be read on a milliameter dial calibrated in knots
and fractions thereof.
This equipment was proved to be accurate to tenths of
a knot. Its accuracy could be checked from time to time
against a measured 200' range inside the testing basin.
The instrument probes could be mounted on boats or barges
and on the equipment being tested in the program. Probes
could also be supported on an instrument platform floating
on the surface of the ocean and supported by sub-surface
buoyancy so that wave action did not produce unacceptable
fluctuations of the indicator.
This equipment proved valuable in measuring currents
generated by air barrier equipment and measuring the speed
at which oil containment booms could be moved through an
oil slick without losing control of the contained oil. The
technology will be described in greater detail in the
section on Mechanical Booms and Air Barriers.
Measurement of "Rate of Rise"
The State of the Art search had disclosed no information
on the rate of rise of oil in globule or droplet form as
it emerges from an underwater position and floats to the
surface. There is a recent report that some work has been
done on this subject by the FWQA laboratories at Edison,
New Jersey.
Rate of rise is of great importance in the design and
operation of oil spill control equipment. In the past,
designers of oil spill control equipment do not seem
to have given enough attention to this phenomenon with
the result that equipment depending on a rapid rate of
rise has proved to be limited in its capabilities.
For example, a tanker might spill oil from the scuppers
into the ocean twenty feet below. The oil could penetrate
to a depth of fifteen feet or more, and might require from
20 to 30 seconds to return to the surface. If the tanker
were moored in calm water, the oil would return to the
surface at the point of entry. If the ship were moored
in a 5 Knot current, slow "Rate of Rise" might cause the
oil to surface 100 feet from the point of the spill, and
a protective boom placed less than 100 feet from the hull
of the ship would be ineffective.
Again, the "Rate of Rise" should be considered when
designing equipment to tow or push a skimmer through an
oil slick. The bow wave from a work boat might easily
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force the oil to penetrate the water to a depth of 4 feet,
and the oil could require 6 seconds or more to return to
the surface. Under those conditions a skimmer placed
close to the bow could overrun the displaced oil before
the oil had returned to the surface.
In recent developments designers are beginning to plan
for this Rate of Rise factor and have provided the
necessary time interval for the oil to return to the
surface after being displaced.
In order to measure this rate of rise, various sizes of
globules of oil were contained in bags of polyfilm or
of thin rubber latex and submerged below the water. The
containers were ruptured at a depth of 10' below the
surface and the rate of rise of the contents was observed
and timed with a stopwatch. It was found that visible
globules of oil could be timed accurately through this
crude but effective procedure.
It was observed that the large globules (ping-pong size
and larger) rose at the rate of 1 second per foot while
the smaller droplets (pinhead size) had a slower rate
of approximately 1% seconds per foot.
This observation is in line with the well known fact that
oil in very tiny particles, such as in an emulsion,
takes much longer periods of time to rise to the surface
of a gravity separating column than oil which is still in
large globules.
Measurement of Thickness of Oil Slick
No equipment or procedure for measuring a thickness of an
oil film was available to the project although such in-
formation would be highly desirable.
A crude technique for accomplishing this was developed by
modifying a standard 5 gallon can so that it could be sub-
merged below an oil film and then raised gently through
the surface so that a representative core sample of a
section of the surface and the sub-surface water could
be lifted out of the ocean in the drum and sent to a
laboratory for analysis. Chloroform evaporation techniques
made it possible to measure the quantity of oil in the
area enclosed by the core sample and by this means the
thickness of the film could be determined. (See Exhibit
1. )
Ambient weather conditions were important to the testing
program and were measured by standard weather instruments
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mounted in a portable console which could be positioned in
work boats to measure wind direction, velocity, temperature,
barometric pressure and humidity at the site of the test
as needed.
The accuracy of such observations could be checked by
referring to records of the U.S. Weather Bureau at the
Portland, Maine International Jetport approximately
three miles from the site of most of our testing work.
Various types of photographic technique were used to
record many phases of the testing procedures and con-
struction details of the equipment being tested. A
library of photos constitutes a comprehensive data bank
of the project. In one of the special tests an attempt
was made to evaluate the capability of infra-red photo-
graphy and other highly sensitive films. Both infra-
red and Tri X Pan film showed excellent definition of
the oil spill on the surface of the water. This is
reported under Appendices
Analysis of the Forces in an Oil Spill
When oil is spilled into ocean waters the volume spilled
is only one factor effecting the area which will be
polluted.
The ultimate size of the spill and the direction which
it travels will be determined by the resultant of a
series of forces which act upon the oil. (Exhibit 2 .)
The forces operating vertically are gravity and the rate
of rise of the oil. The latter is a function of the
specific gravity of the oil and of the water in which
the oil floats.
The horizontal forces which effect the spill include
"the spread effect" which urges the oil to travel out-
wardly from the center of the spill, the "surface tension"
of the oil which tends to hold the oil in one mass until
other forces overcome it, "current effect" which is the
influence of river or tidal current and "wind effect"
which is the force exerted against an oil slick by surface
winds.
In addition to the 6 forces listed above various types of
marine activity can act upon an oil spill in an almost
infinite variety of unpredictable combinations.
Wave action can push some portions of an oil spill above
or below its normal position above or below the surface
of the water.
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The wake of a boat or turbulence from its propeller can
generate violent combinations of forces in an oil spill
so that oil is forced far below the surface and in some
cases oil and water are forced into an emulsion state.
At one time or another in the testing program all of these
types of extraneous force have been experienced. In the
reporting of such forces, language has been used which
should be useful and easily understood by lay personnel
operating oil spill control equipment.
It is apparent that additional research should be carried
on to investigate the forces in oil spills and it would
be helpful if a universal nomenclature could be adopted
so that all parties concerned will speak the same language
in discussions of this phenomenon.
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MECHANICAL BOOMS
Designs Available to the Testing Program
The mechanical booms available to industry at this time
represent a wide variety of designs and materials.
For ready reference, we have classified each boom as a
"curtain boom" or as a "fence boom".
"Curtain booms" include the following components:
A surface float which acts as a barrier on the
surface and which supports a sub-surface curtain.
The curtain is flexible and provides a barrier below
the surface to a depth of as much as 18" or more.
The flexible curtain may or may not be stabilized by
weights or a cable to provide greater resistance to
sub-surface currents.
"Fence booms" include:
A vertical "fence" or panel extending above the
surface and below the surface, thus providing both
freeboard above the surface and draft below.
Flotation which supports the "fence" in a vertical
plane. The lower edge of the panel may be stabilized
or strengthened by a cable or chain to increase
structural integrity.
Each boom has its special characteristics, but each is
directed at one common objective; namely, to counteract
the forces which are exerted upon spilled oil and thereby
to assist in the control and eventual clean-up of the
spill. (See Exhibit 3 .)
In this project, 10 different models of boom were tested
extensively under controlled conditions, and at the
Louisiana spill (Appendix B. ) two additional designs
were observed in action.
"Curtain" booms tested included:
C-l A flexible, plastic curtain extending 12" below
surface, supported by a series of 6" cylindrical,
closed cell, foamed plastic floats 10 long,
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having 3" of freeboard. Boom sections of
various lengths are joined by stainless steel
connector plates. One-quarter inch stainless
steel cable runs the length of each section.
C-2 Same construction as above, with 8" curtain and
6" cylindrical floats 41 long.
C-3 Same construction as above, with 6" curtain and
4" float.
C-4 Same construction as above with 10" curtain and
6" float.
C-5 Same construction as above with 6" curtain and
4" float. Utility boom only. Not submitted for
testing.
C-6 6" float with 12" curtain. Float chambers
filled with polystyrene beads. Curtain stabilized
with plastic keelsons sewed into bottom edge and
with tension cable along bottom edge and attached
to towing hitches.
C-7 6" foamed plastic floats 9' long enclosed in
pocket of 1 piece nylon fabric, weighted with
lead at bottom edges. Curtain has 9" draft.
Float provides 4" of freeboard.
Light Fence Type booms
L-8 24" aluminum panels with rubber connecting
panels and plastic foam buoyancy pads.
L-9 36" reinforced nylon fabric with plastic floats.
L-10 36" sheets of rubber-asbestos floated verti-
cally by plastic buoyancy strips.
Heavy Fence Type booms
H-ll Flexible, reinforced fabric barrier supported
by integral float chambers. 30" freeboard
and 66" draft.
H-12 4' x 8' plywood supported by 55 gallon drums
and connected by flexible rubber panels. Sub-
surface curtain hangs below lower edge of
plywood to depths of 5'. Freeboard of 2'.
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As soon as the existence of the project became known, manu-
facturers and suppliers of mechanical booms (and of many
other types of equipment) were prompt and generous in
offering their equipment for testing purposes.
The booms listed above were selected as representative of
the various categories available. It was impossible to
test all equipment offered because of time and budget
limitations.
In addition to loaning equipment, manufacturers visited
the project to instruct personnel in assembly, launching
and maneuvering of the booms. This insured that equip-
ment would be operated properly during testing procedures.
Throughout the project donors of equipment have been most
cooperative in assisting with problems encountered in
testing. In addition, they have welcomed comments and
suggestions for improving their equipment. In many cases
changes have already been adopted as a result of the testing
program.
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Functions of Mechanical Booms
There were no accepted criteria of boom performance at the
time this project was initiated. Establishment of such
criteria was a major objective of the project.
Before meaningful criteria could be adopted, project
personnel acquired practical knowledge of boom operations
by testing booms under a wide variety of conditions,
developed standard testing procedures, and learned the
functions which a boom should perform in a complete system
of oil spill clean-up equipment.
Some of the principles of boom operation are summarized
in the following paragraphs as a background to the evalu-
ation criteria which were ultimately adopted. It is hoped
that this summary will be valuable to assist prospective
users in determining which boom might best suit the
specific problems of the oil spill in which the boom will
be used.
It became evident that surrounding and containing an oil
spill with a boom is of very limited value unless the
operation contributes to the successful removal of the oil
from the water. Consequently in any consideration of
booming technique the operator should plan his maneuvers
to assist the skimming and other clean-up techniques which
follow.
Most operational spills are of the limited variety. That
is, a finite quantity of oil drops into the water, the
source of the spill is emptied or blocked off and there
is no continuing flow of oil to enter the area.
To be useful against a limited spill, a boom must be able
to stop the spread of the oil until clean-up methods can
be implemented.
Under calm air and water conditions a boom would have to
surround the spill completely in order to accomplish this.
If sufficient boom is available any of the curtain or
fence booms would be effective.
In an unlimited spill the source of the oil continues to
flow for a long period of time before it can be effectively
stopped.
Under such conditions there is seldom enough boom at hand
to contain the large volume of oil. Instead, the boom
must be used to divert the flow of the oil effectively
to the skimmers, suction nozzles or other equipment
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which is used to extract the oil from the water.
There are many alternative arrangements whereby booms may
be used for this purpose. Some of them will be discussed
in more detail in Appendix C. of this report.
When conditions of wind, wave and weather are present, the
problem of containing a spill or of diverting its flow
becomes more difficult, and a boom must be judged on its
ability to conform to the wave profile, to withstand the
stresses set up by wave action and wind action and to
retain the design profile of its barrier. These qualities
are essential if it is to function effectively. In addition
to the operational characteristics described above, the
boom must be graded for its ability to withstand extended
exposure when stored or deployed in salt water for a long
period of time.
Additionally, the ease with which the boom can be deployed,
towed to the scene of a site, recovered, cleaned and stored
for further use is very important.
In order to observe each test boom under controlled con-
ditions, a Standard Testing Procedure was developed. This
provided comparative data on each type of boom tested.
The procedure included tow tests, diversion tests and care-
ful analysis of problems incidental to rigging, mooring,
deployment and recovery, cleaning and use of accessories.
In tow tests, a length of boom was towed from outriggers
mounted on a work barge (See Exhibit 4. )
Oil was spilled into a loop of the boom during forward
movement at the rate of IK to 3K's. This tested the
ability of the barrier to accumulate oil in the vee of
the boom and to contain the oil in that position at
varying speeds. Skimmers were operated in the vee of
the boom to remove the oil thus contained. Sensitive
marine speedometers were used to measure speeds relative
to the surrounding water. As shown in Exhibit 4. , out-
riggers spanned a distance of 38'. Tow lines, 16' long,
led from the outriggers to the end of the boom being towed.
A length of boom being tested thus forms a catenary as
shown on the exhibit.
With the boom moving across the water at relative speeds
of up to 3 knots, generation of current, turbulence and
eddies in front of the vee of the boom can be observed.
It is also possible to measure the forward speed at which
the turbulence begins to pull the contained oil under-
neath the boom. The action of the sides of the boom
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forward of the vee in diverting a surface film could be
effectively observed and measured by using flotation
material (chips, talc, sawdust, and shavings) in addition
to oil. The effects of draft and freeboard were observed
and measured. In the course of such testing it was evi-
dent that turbulence is the major cause of losing oil
underneath the boom and that wave action is the major
cause of losing oil over the top of the boom.
In these standard tow tests the formation of a smooth
surfaced pool of calm water in the vee of the boom was
apparent. In the configuration shown in Exhibit 4. the
"pool" extended from 2' to 6' ahead of the vee of the boom.
The forward edge of this pool was marked by a line of
ripples similar to a tide-rip. Contained oil tends to stay
in the "pool" area between the ripples and the boom. A
section through the sub-surface structure of this oil
pool would approximate that shown in Exhibit 5
The pool which can be maintained during towing at a
speed of 1/2 to ih knots is sufficiently large and stable
to provide a suitable area for the operation of a skimmer.
In many of the tests a skimmer was towed behind the barge
so that oil being diverted into the pool could be skimmed
and pumped to the tank on the barge as fast as it was
being spilled overboard from the barge.
To accomplish this operation without leakage of the oil
under the boom, relative speed of the boom and the water
must be slow enough to avoid generation of excessive
turbulence. When the turbulence begins to cause leakage,
forward speeds must be reduced.
Some booms will not contain oil at a relative speed of more
than .5 knots. Others have contained oil at a relative
speed of 1.5 knots. In general, the fence type booms
contain oil at higher speeds than the curtain type booms.
Booms can be used to encircle a spill and to move the spill
by towing the boom, but this must be done very slowly at
speeds of 1% K or less. (See Exhibit 6. )
Observation of tow tests in waves up to 4' high led to a
conclusion that in general the "fence" type booms with
their high freeboard and rigid sub-surface structure
showed promise of containing oil under some severity of
wind and wave action. The "curtain" type barriers
characterized by a low, rounded freeboard and a flexible
sub-surface curtain were more suited to use in smooth
water, in shallow water and under limited wave action
conditions.
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The tests described above indicated that outriggers pro-
vided effective maneuvering control of a flexible boom
so that a pool of oil would form in the arc of the boom
and effective skimming could be accomplished in the pool
thus formed. The installation of tanks and pumping equip-
ment made possible a complete clean-up system which could
operate as a unit.
Towing a boom in the form of a funnel pointed toward a
skimmer gave additional information about the capabilities
of the booms. Exhibit 7. shows a typical tendency of a
boom to bulge as the area between the two booms becomes
squeezed into a narrow channel on its way to the skimmer.
Correction is needed because as soon as the boom starts
to divert the oil more than twenty degrees from its normal
path turbulence can be expected under the bottom of the
boom and this will result in loss of oil.
To avoid this the type of rigging shown on Exhibit 7. can
be used to minimize the tendency of the boom to bulge.
Tow tests also showed that too much tension on a boom
reduces the boom's ability to flex in accordance with the
wave profile, sometimes even to the point that portions
of the boom can be completely submerged by a wave 3' or
4' high. This results in substantial loss of oil at the
point where the boom is submerged.
"Funnel" tests showed that oil or other flotsam tended to
hug one side of the funnel or the other depending on the
direction of the controlling force which was moving the
oil along the surface.
If the wind were the controlling factor and blew toward
one side of the funnel, the oil would hug the boom on that
side. Similarly, if the current proved to be the stronger
factor, the oil was carried toward the down-current side
of the funnel and the boom on the other side had little
work to do. (See Exhibit 25. )
Single Boom Diversion Tests were developed in the later
stages of the project. Tests indicated that a single
boom could be used effectively to steer an oil spill away
from a sensitive area or to divert its path to an area
favorable for good skimming operations.
In small scale Diversion Tests it was noted that the "down-
wind" boom not only diverted the path of the oil but tended
to keep the stream of oil compact and narrow, thus creating
ideal conditions for the skimming operation which was to
follow. (See Exhibit 8.)
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The towing operations disclosed problems with the towing
hitches and connectors which join one section to another.
In one instance, wave action loosened connector bolts
on one design of connector. These weaknesses were relayed
to the manufacturers and steps have been taken by them to
modify or re-design as necessary.
The connector plate supplied by one manufacturer was not
compatible with a boom designed by another manufacturer.
A new design was necessary whenever two different booms
were joined end to end. It is strongly recommended that
an industry committee be formed to work out a universal
design for joining one boom to another of different make
just as fire hoses are equipped with universal couplings.
There were no mechanical failures of any of the booms
during the conduct of these standard tow tests in Portland
Harbor. However, later operations in rough water conditions
did produce structural failures such as ripped fabric,
tangled rigging and broken components.
Rough handling, exposure to deterioration, high speed
towing for deployment purposes and the twisting action
of rough water may generate forces which are not apparent
in the standard tests and which are more likely to cause
physical damage to a boom.
Tow testing procedures indicated that the ability of a
boom to hold together when strung across a 5 or 10 knot
current may be an indication of the material strength of
the boom but such ability is not an indication of the
boom's effectiveness in containing spilled oil. Evaluation
of the boom should depend primarily on its ability to
contain oil and only secondarily on its brute strength.
The deployment of booms at the site of a spill has created
some handling problems. The Maine Port Authority has
successfully used a catamaran structure to store 1500' of
curtain type boom on its deck. The boom can be arranged
in a fanfold pattern when not in use. The catamaran thus
serves as a carrier which can be towed rapidly to the source
of a spill. The boom can be played out rapidly and
effectively without danger to personnel or damage to the
boom, just as fire hose is played out from the rear of a
fire truck.
Deployment of any boom which is equipped with chains,
cables or other loose lines can lead to tangles of the
lines or cables with other parts of the boom. This has
been a real problem on one of the "fence" designs and
corrective action has been taken by the supplier.
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In all instances where a boom was immersed in salt water
for 30 days or more, the booms accumulated some quantities
of marine growth on sub-surface sections. In permanent
installations, such growth could accumulate to create
problems and hazards. Measures should be taken to combat
marine growth or to provide for an effective means for
periodic removal of such growth.
Design of boom handling equipment should receive attention
by the suppliers. Manpower is always at a premium, and any
device which will take the muscle out of launching and
recovery will be most welcome.
Evaluation Criteria
Considering all the operations factors listed above,
evaluation criteria must be closely related to practical
considerations if they are to be effective.
Furthermore there are so many qualities to be considered
and environmental factors are so varied that evaluation
must include judgments by qualified personnel as well as
mathematical measurements of testing procedures.
In order to evaluate each boom, 19 characteristics of
booms have been listed in groups as follows:
Performance under Calm Water conditions
Containment The ability to restrain a spill against
the forces which seek to spread the spill
over a greater area
Compaction The ability to gather the oil inwardly
so that it covers less area and the
slick becomes thicker to assist the
skimming efficiency
Towing The ability to move the spill across the
surface of the ocean in a direction
counter to that urged by wind and current
forces
Diversion The ability to divert the flow of a
stream of oil counter to the influence
of wind and current and to bring about
a change in the flow of a stream emanating
from an oil spill
Protection The ability to function as an inert
barrier in the path of an oil slick
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which is threatening a sensitive shoreline.
(Recreation area or wild-life refuge.)
Ability of the boom to perform the above functions
in the presence of severe wind or wave conditions.
as follows:
Ability of the boom to flex and conform to wave
profile
Stability of the boom in holding its preferred
position in the presence of "knockdown" wind gusts
or squalls
Structural integrity when subjected to the strains
imposed by heavy seas and strong winds
Dependence on critical rigging or mooring operations
or special handling techniques
Design Convenience Factors
Ease of assembly when received from the manufacturer
Ease of launching from boat or dock
Performance while being towed to site of spill
Ease of coupling one section of boom to another
Ability to make a leakproof attachment to a dock or
boat
Compatibility with other booms or with other oil
spill equipment
Ease of hauling onto boat or dock for cleaning,
storage or transport
Cleaning of oil or marine growth
Shelf Life Factors
Shelf life on-shore during periods of non-use
Deterioration when deployed in the water for extended
periods of time in stand-by status
Project personnel made independent judgments of each boom
on the qualities noted above. Performance on each item
was graded from 1 to 10, and bonus points were awarded
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for those factors which were considered to be the more
important.
Five "curtain" type booms were graded on the system
described above, and three "light fence" type booms and
two "heavy fence" designs.
On the basis of total points scored by each boom, the
light fence booms scored appreciably ahead of the curtain
type booms. The heavy fence booms, graded on the basis of
their performance at the Louisiana spill, scored better
than the curtain type booms but by a more narrow margin.
Results of the grading are summarized in the Tables on
the following pages.
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COMPARATIVE GRADES OF 10 MECHANICAL BOOM DESIGNS
CURTAIN BOOMS
LIGHT
FENCE BOOMS
HEAVY
FENCE BOOMS
GRADED
BY
C-l
C-2
C-4
C-6
C-7
Total Points
Relative Rank
536
5
570
4
507
8
524
6
469
9
L-8
L-9
L-10
513
7
664
3
711
1
H-ll
H-12
570
4
672
2
CD
I
NOTE: Heavy Fence Booms graded only on performance in Louisiana spill.
Booms C-2 and H-ll tied for fourth place in standings.
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AVERAGE SCORES BY GROUPS - Countering Oil Spill Forces
i
no
VD
I
Curtain
Light Heavy Best
Fence Fence Group
Remarks
Class l.
Ability to Counter
the Forces in an
Oil Slick in
Smooth Water
Conditions
a. Containment 7.2
b. Compaction 5.9
c. Towing a pool
of oil 7.5
d. Diversion 9.9
Protection 6.1
13.3 18.5 Heavy
Fence
11.6 5.0 Light
Fence
13.2 12.0 Light
Fence
17.2 12.0 Light
Fence
12.0 13.5 Heavy
Fence
Heavy Fence group has higher
freeboard and greater draft.
Easiest to maneuver. Curtain
booms with short floats are
easier to handle in the water
or on land than those with long
floats.
Fence structure maintains
vertical profile.
Mobility, maintains vertical
profile.
Most freeboard and draft.
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AVERAGE SCORES BY GROUPS - Rough Water Performance
o
l
Light Heavy Best
Curtain Fence Fence Group
Remarks
Class 2.
Ability to Control
Forces in Rough
Water Conditions
a. Conformity
to Wave
Profiles
b. Stability
against
knockdown
9.3
7.1'
16.0 17.0 Heavy Both fence types are far
Fence ahead on this item.
11.9 14.5 Heavy
Fence
Heavy weight is a stabilizing
factor.
Structural
integrity
11.5
Dependence on
Critical Rigg-
ing operations 7.4
12.3 14.5 Heavy
Fence
Any design can be wrecked if
not moored properly.
9.6 11.5 Heavy Basic strength of Heavy Fence
Fence types makes them less critical,
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AVERAGE SCORES BY GROUPS - Design Factors Affecting Deployment
i
u>
Curtain
Light
Fence
Heavy
Fence
Best
Group
Remarks
Class 3. Design
Factors Affecting:
A. Assembly
B. Launching
C. Towina to
site of
spill
D. Coupling
E. Attachment
F. Compatibility
G. Hauling
11.9
12.3
11.2
11.2
6.9
7.9
12.5
10.7
11.6
9.7
9.5
7.7
8.6
9.5
2.5
11.0
12.0
10.5
9.0
9.0
8.0
Curtain
Curtain
Heavy
Fence
Curtain
Heavy
Fence
Heavy
Fence
Curtain
Light weight and portability
were generally good in the
Curtain group, while power
equipment is needed for assembly
of Heavy Fence group.
Weight is controlling factor.
Proper rigging of towing
bridle is critical on Light
Fence type.
All groups need better hitches.
All groups scored poorly on
this factor.
This factor needs much more
attention.
Light weight scores heavily
H. Cleaning
6.1
6.0
3.0 Curtain
for Curtain Booms. Power
equipment needed on Heavy
Fences.
Hand labor needed on all
types.
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AVERAGE SCORES BY GROUPS - Shelf Life Factors
Light Heavy Best
Curtain Fence Fence Group Remarks
Class 4.
i On Shore Storage 10.4 8.0 3.0 Curtain Light weight and easy to store
^ between periods of use.
Water Storage 13.0 12.4 14.5 Heavy Generally good, but very light
Fence materials on Curtain group are
fragile under rough handling.
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Conclusions and Recommendations
Conclusions
1. The use of a boom to control the movement of an oil slick
can accomplish these tasks:
a. If complete encirclement is possible, the boom
can
1) Prevent further spread of the slick, and
2) It can contain a large amount of oil - up to
at least 2" of film thickness - as long as
wind and wave permit.
b. As a barrier across the path of a spill, a boom
can
1) Delay passage of the slick until depth of oil
pool against the arc of the boom approaches
two-thirds of the draft of the boom, or
2) Until current and turbulence pull oil under the
boom.
c. Used as a sweep or trawl, the boom can
1) Gather pools of surface oil in the arc of the
boom so that skimming operations can be
effective in those areas.
2) Compact widely scattered puddles of oil or
very thin films so that the efficiency of
skimming can be improved.
3) Tow or pull limited areas of slick from one
location to another to avoid sensitive areas
or to reach fixed oil-removal installations.
d. Used as a means of guiding the flow of an oil
slick, the boom can
1) Divert the flow of a spill by as much as 20°
from its natural path.
2) Lead a slick to the area where skimmer equip-
ment is operating.
3) Limit the spread of a flowing spill in the
area near the source.
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2. For use in rough water, a minimum of 12" of freeboard
is essential to reduce over-flow by surface waves and
wind-driven spray.
3. Present designs can be effective when operated by
trained personnel, but continued development of
accessories and easier handling techniques are needed.
4. The overall evaluation of various styles of mechanical
booms suggests that
a. The curtain booms can be effective in shallow water
and calm wind and wave conditions. As such, they
offer very good cost effectiveness in protected
waters.
b. The light fence types offer the greatest protection
and versatility for most situations, though their
effectiveness may be very limited in shallow waters,
(Less than 2 feet.)
c. The heavy fence types are handicapped by heavy
weight, and the need for mechanized handling
equipment but their extra freeboard and stability
can be very valuable in rough water conditions.
Recommendations
The following items should be considered by any supplier
or manufacturers of boom equipment:
1. Improve the part that the boom can play in a complete
clean-up system by
a. Making it compatible with other equipment.
b. Making it compatible with other booms.
c. Increase the ease of launching and recovery from
a work boat or dock.
d. Design the boom to assist the clean-up operation -
whether by skimmer, chemical or other device.
2. Improve its ability to exert more force against an
oil spill.
a. Consider the addition of air or water jets to
augment its abilities as an inert barrier.
b. Consider the aerodynamic possibilities of the
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freeboard structure as an assist in rough water.
3. Explore the use of multiple booms, with a secondary
structure to act as
a. A channel to pick up small patches of oil which
may get past the primary structure.
b. An auxiliary structure to act as a wave damper in
choppy water.
4. Designers should explore the use of a material to
limit the accumulation of marine growth on a boom,
and should provide a method for cleaning such growth
from a boom.
5. More attention needed on leak-proof fastening of
booms to docks, boats and skimmers.
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AIR BARRIERS
Designs Available to the Testing Program
When this project was activated the Maine Port Authority
expressed a definite interest in using an air barrier at
one or more critical locations in Portland Harbor.
Correspondence was initiated with two manufacturers of
air barrier equipment, but it was evident that each one
preferred to engineer a custom design for a specific
application at a designated location rather than to supply
equipment for a testing and evaluation program. This plan
did not meet the requirements of the project, which in-
volved tests at several locations in the Portland Harbor
area.
Efforts to obtain an air barrier for testing purposes
disclosed that Maine sardine fishermen have for years
used air barriers to pen sardines, inside a cove while
netting takes place.
1600' of such barrier was acquired for the project. A
portion of the length was of 3/4" I.D. flexible p.v.c.
hose and the balance was of 1" I.D. hose.
With this substitute equipment the tests described later
were performed. Those tests demonstrated many of the
characteristics of air barriers, or "bubble curtains"
as they are sometimes called.
In November, 1969, one manufacturer offered an air barrier
of 1" I.D. aluminum pipe for the testing program.
The offer was most welcome and arrangements were made to
conduct tests in waters up to 50' deep adjacent the
former Navy refueling docks on Long Island in Casco Bay,
Maine. Personnel who designed the barrier accompanied
the equipment to Portland to assist in a three day testing
program under a wide variety of surface conditions. During
theses tests attempts were made to take underwater photos
of the pattern set up by the bubble barrier but scuba
divers were unable to cope with the combination of murky
water and the strong vertical currents set up by the
equipment being tested. Surface conditions throughout
the tests were recorded on colored slides.
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Testa and Evaluations
The series of tests was directed toward the following
objectives:
1. To determine the problems inherent in assembling,
launching and operating an air barrier in Maine waters.
2. To determine the basic characteristics of the air
barrier curtain.
3. To determine the air barrier's basic ability to
counteract the forces which affect an oil spill.
a. When working from a permanent installation on
the bottom.
b. When working from a supported position at a
selected depth.
c. When used as a highly mobile unit for sweeping,
collecting or diverting an oil spill or other
flotsam.
Note: In measuring the forces generated by the air
barrier curtain marine speedometers were used to
establish that the air bubbles generate surface
currents floating away from the "Z" line (the Z
line is shown in Exhibit 9 .) The surface
currents are generally at right angles to the Z
line. Using"the same technigue it was found that
very little horizontal current is present at
depths of 6" and 18" below the surface except
within 2' or 3' of the Z line. (See Exhibit 10. )
However, there is also a vertical current of some
magnitude generated by the rising air bubbles. The
potential of this phenomenon has not been fully
explored.
Tests of Maine Port Authority Air Barrier (Floating and
Fixed) at Test Area
Maine Port Authority's Air Barrier, about 200' of 1"
flexible hose and about 400' of 3/4" flexible hose,
with small holes (Approximately 1/32" diameter) spaced
18" apart, was used.
The first test with the air barrier was performed by
placing the 200' of 1" air barrier hose across the
outboard end of slips 3 and 4 at the testing site. Air
was supplied from a 125 cfm air compressor operating
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at 100 psi. When air was first applied to the air
barrier hose it required less than two minutes for
the air to displace the water in the hose for the
full 200' length. The surface boil appeared at the
compressor end immediately and extended rapidly for
the full 200' across the slips.
The turbulence created by the air barrier varied from
6' to 8' wide and consisted of a surface current moving
outward from the center line (the Z line) of the barrier
In this surface current, pieces of seaweed and flotsam
were brought to the surface by the upward motion of
the air and water and carried outward by the water
currents created. Near the outward edge of the
surface current these objects dropped down to lower
depths.
These first observations indicated that an air barrier
creates sub-surface vertical currents due to the
rising air. Surface currents extend outward from the
center line of the barrier as a result of the upward
vertical current.
A test series was performed to determine the action of
the air barrier on partially submerged objects and
the effect the air barrier would have on tidal or
current flows. The 400' of 3/4" hose was coupled to
the original 200' of 1" hose and layed on the bottom
of the slips as shown in figure A.B. 1. To study the
effect on submerged objects, 16 ounce cans filled
with water were suspended from small floats. This
arrangement provided a reasonably large suspended
object and a condition of nearly neutral buoyancy.
With the air barrier on, it was observed that the
cans in slip #3 collected at the sharp vee and were
carried through the air barrier by the outgoing tide.
The cans in slip #4 escaped from the slip into the
open passage and moved out at an accelerated rate.
This indicated that the air barrier had some effect
3" below the surface and to some extent diverted the
outgoing tide to the open area. This testing was
reported after removing the sharp vee and although
the cans in slip #3 drifted toward the barrier none
of them penetrated through the vertical currents it
generated.
Additional tests were conducted using 200' of the 1"
hose stretched across slip #3 and halfway across slip
#4. The cans which formerly were suspended 3' below
the surface, were changed to one group 3' below the
surface, one group 7' below the surface and the third
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group 12» below the surface. These tests, which
were conducted on both incoming and outgoing tides,
showed that the air barrier diverted the tidal
flow to the extent that no cans crossed the air
barrier and most of them were carried by the current
to the opening in slip #4. It was also observed that
the rate of tidal flow through the narrow opening in
slip #4 was more than twice the normal rate of tidal
flow in and out of the slips when the air barrier was
not running. These tests clearly indicated that an
air barrier can be used to partially divert a tidal
flow or current having a velocity of 1^ K or less.
(Exhibit 11.)
Tests on the surface effect of air barriers using talc
showed that during a period of wind velocity of 15 to
18 knots that talc blown across the surface came to a
stop as soon as it met the outgoing surface current
some 4 to 61 from the center line of the air barrier.
When there was a sharp vee in the air barrier some
talc would escape through the irregular surface pattern
at the vee. When the vee was removed and replaced by
a gentle curve the loss of talc was stopped.
During these tests it was also observed that although
the water surface appeared to be relatively clean,
traces of oil and other flotsam were collected at the
edge of the air barrier current after about ten minutes
of operation. The restraining effect of the current was
clearly demonstrated when a styrofoam coffee cup was
blown toward the barrier and was stopped by the
surface current created by the air barrier. This same
result occurred using styrofoam balls and rolls and
various floats and buoys. In all tests it was apparent
that it was the outward flowing surface current which
acted as the barrier, and not the height of the boil.
Therefore air barrier design should be based on creating
the maximum upward vertical current by the rising air
bubbles, as it is this vertical current which becomes
the outward flowing surface current.
To determine the vertical currents and resulting out-
flowing surface currents at various air barrier depths
and air pressures, the air barrier was secured to a
line stretched across slip 3 just below Mean Low Water.
Tests were run at each foot rise of the tide.
Operations at less than 4' depth resulted in a poor
surface current pattern. This was caused by the wide
(18") spacing between the air holes which resulted
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in a broken surface pattern. As the depth increased
from 41 to 7 or 8', the outward flowing surface
increased. For depths greater than 81, up to the
maximum of 16' observed during these tests, the out-
ward flowir.g surface currents were measured at .7 K
close to the Z line and a .2 K at 20' from the Z line.
For each different depth of air barrier, observations
were made for 40 psi, 70 psi and 100 psi air pressures.
At 40 psi there was not a sufficient amount of air
discharged to create a steady and uninterrupted out-
ward flowing surface current. Both the 70 psi and
100 psi operating pressures created the desired
outward flowing surface current. The area effected
by the current increased from 3' to 4' from the air
barrier center line at 70 psi to 6'-8' at 100 psi.
Several tests were made to determine the effectiveness
of an air barrier used to sweep an area. For these
tests the air barrier was suspended at various depths
for 3' to 81 from floats. About 40' of air barrier
was stretched between the outriggers of the barge.
A 25 cfm compressor on the barge supplied the
air at 75 psi. When the barge was towed at any speed
over 2 knots the outward surface current created by
the air barrier was broken up as a result of the
forward motion. Talc or other floating objects were
able to pass quite freely through the barrier. During
these tests it was observed that the air bubbles rising
from the air hose appeared to be much larger and fewer
in number than were observed when the air barrier was
stationary.
Another series of tests was conducted using 80* of
air barrier suspended at 5' and at 10' below the
surface. During this series of tests the air was
supplied from the shore based 125 cfm air compressor
at 100 psi. The free end of the air barrier was
towed to sweep a circular area around the end of the
pier. Good sweeping action was obtained, particularly
near the pier where the barrier was travelling at slow
speed. Again it was observed that there v/as a tendency
for the air to form large bubbles as the air barrier
moved through the water, and that fewer large bubbles
create less outward flowing surface current than a
larger number of small bubbles.
To determine the bubble patterns for different size
holes at different air pressures and depths, a series
of holes, spaced one foot apart, was drilled in a
12' length of 1" I.D. aluminum pipe. The holes were
drilled with even numbered drills, from #60 (.040")
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to #40 (.098").
The test pipe was suspended from the outriggers across
the end of the barge, and the air was supplied by a 25
cfm air compressor mounted on the barge.
These tests showed that the bubbles of air escaping from
the largest hole (#40 drill - .098") were no larger
than the bubbles escaping from the smallest hole
(#60 drill - .040"). However, because more air was
escaping from the largest hole than the smallest hole
(approximately 6 times the volume, based on the hole
areas), the outward flowing surface currents above
the largest hole were significantly greater than the
currents above the smallest hole. During the series
of tests the depth of the air barrier was varied from
3' to 10' and the air pressure was varied from 5 psi
to 10 psi. For each combination the surface current
pattern over the largest hole was visibly stronger
than the pattern over the smallest hole.
During these tests it was again noted that when the
boom was stationary or moving slowly the pattern of
small bubbles remained, but when the barge was moved
more rapidly larger bubbles were formed.
Air bubbles rising from water do not assume an aero-
dynamic shape and travel in a straight vertical path
unless lateral current is present. The shape of an
air bubble is generally circular, and the bubble
moves from side to side as it rises. The water
passing between two adjacent rising bubbles forces
them apart, so that the pattern formed by the air
bubbles coming from a single hole is an inverted
cone.
This test of Commercial Air Barrier equipment was
conducted on December 13, 1969 at King Resources
Long Island Pier in Casco Bay, with a 10 to 15K wind.
The barrier equipment consisted of five 20' lengths
of 1" I.D. aluminum pipe drilled every 6" with a
1/16" hole. The sections were coupled together with
a semi-flexible compression type coupler.
The barrier was initially placed in 40' of water
alongside the pier and was coupled to a 600 cfm
compressor with 50' of 2" I.D. rubber hose. The
operating pressure at the compressor was 45 psi.
When the system was activated a good boil appeared
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on the surface in 1-1% minutes and within 3 minutes
the surface current was established the entire length
of the barrier. The surface boil was apparent but of
more importance was the surface current extending 15
to 18' on either side of the Z line. This action
completely knocked down the 1' chop that was on the
water. The outflow of the current was very apparent
and its affect on the waves was quite spectacular.
Several floating objects and standard oil substitutes
were placed in the water up-wind of the barrier and
not one of them approached within 15' of the Z line.
The floats that were attached to the barrier to spot
its location were also driven away from the Z line
as far as their lines would allow them to go and the
current at the base of these floats was quite apparent.
The work boat was sent into this current using its
engine to hold a fixed location and currents of lh
to 2K were recorded close to the Z line.
During this test divers were attempting to take
pictures of the bubble pattern as it left the pipe,
using 1500W waterproof lights. They were not very
successful for several reasons. The water itself
was not too clear, the bottom was being stirred up
by the action of the barrier and it was reported by
the divers that the turbulence of the water made it
very difficult for them to maintain their position
while photographing.
For these reasons the barrier was raised to 20' of
depth to eliminate the disturbance of the bottom.
There was no apparent change in the surface pattern
of the barrier. The ascending bubbles did not appear
to change shape or size due to the change in depth.
The current measurements made by the work boat did
not change significantly and floating objects were
held at the same distance as before.
This barrier from all indications was very successful
and if it is used as a device to protect sensitive
areas in a fixed location it could be effective. Further
studies of air barrier applications should be under-
taken to determine its adaptability as a diverting
boom, a sweeping boom and a mobile containment boom.
Air holes in an air barrier pipe have a tendency to
become plugged (this was true of both types of equip-
ment tested.) This spoils the pattern of the barrier
and reduces its efficiency.
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Test operations indicated that:
a. Frequent shut-down of the system tends to pull
foreign matter and marine growth into the air
holes from the surrounding water.
b. The suspended barrier pipe (61 above the bottom)
was less susceptible to plugging than the pipe
laying on the bottom.
c. The problem can be minimized by maintaining an
air flow at low pressure as a stand-by procedure,
and then increasing the pressure to the range of
maximum effect when need arises.
d. As an alternate to c. above fresh water can be
pumped through the air hose during stand-by
periods. A low pressure water flow will keep
the air holes clear. When barrier operation is
required, the water is turned off and air pressure
is applied.
Conclusions and Recommendations
Tests described above led to the following conclusions:
1. Air Barriers hold real promise for fixed installations
across slips and parallel to unloading docks, for
a. Continuous stand-by operation at reduced air
pressures should keep the hose ready for instant
use, with maximum air pressure to be used only
in emergencies.
b. The Air Barrier generates its strongest horizontal
forces at or near the surface of the water.
Vertical forces are also present, but their
effect on oil spills needs additional research.
c. The sub-surface air curtain can partially divert
sub-surface tidal currents of low velocity.
d. An air barrier can be almost as mobile as a
mechanical barrier. Compressors, buoys and other
accessories for operating an air barrier can be
ship-mounted without undue difficulty.
e. The Air Barrier's ability to contain or divert
oil in rough water has been tested by the manu-
facturer but results have not yet been published.
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2. Some models should be sufficiently versatile to
operate in several different applications.
We realize fully that a general purpose model might
entail a compromise with some engineering refinements
which could be realized if the barrier were engineered
for a specific task.
3. The Air Barrier may perform effectively in rough water
conditions where the full force of surface waves and
wind would not be exerted against the air supply pipe
suspended sub-surface.
4. An Air Barrier used to surround a ship at a pier or
at a single-point-mooring has some potential economic
advantages as follows:
a. Moderate installation costs
b. Minimum manpower to activate and monitor its
performance
c. Will not limit the access of supply and work
boats to the tanker
d. Not susceptible to accumulation of ice in freezing
weather
Recommendations for Further Testing and Development
1. The potential for permanent installations should be
researched in more detail because of
a. Possibility of low installation costs and low
upkeep
b. Possibility of using an air source which could be
inter-changeable with other productive work when
the air barrier is not required
c. The barrier can be quickly and effectively acti-
vated by one man when needed
2. The potential of a mobile air barrier should be
explored.
3. Rough water performance needs further research and
demonstration.
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SKIMMERS
The Urgent Need for Skimming Capacity
The second Phase progress report on this Project, (October
1969) included the following statement: "the biggest
problem in developing a viable system (for oil spill clean-
up) is that of designing improved skimmers "
That statement was borne out at the beginning of the
Louisiana oil spill (See Appendix B. ) when the need for
massive skimming capacity was so imperative. There simply
were no high volume skimmers available from the equipment
industry in this country. Best estimates at that time
indicated that skimming capacity would need a total through-
put volume of 75,000 barrels of liquid per day (@ 42 gal.
per bbl) at an oil/water ratio of 10% (10% oil to 90%
water) if they were to contain the expected spill.
Fortunately, this project had tested one design of skimmer
which indicated that the circular weir principle of skimming
had real potential for large volume operations. In addition,
this principle had the virtue of simplicity and could
readily be designed into a large volume skimming nozzle.
Also, the resulting design could be built rapidly by most
welding shops.
The design (See Exhibit 12. ) proved to have a through-put
of 420 GPM using a 4" Impeller Pump driven by a diesel
engine. 420 GPM is equal to 10 bbls (a standard oil barrel
per minute of 600 barrels per hour or 14,400 barrels per
24 hour day. Six of these skimmers (referred to as the AK
skimmer) could provide a through-put of over 80,000 bbls
per 24 hour day, if each could be used at full capacity.
Twenty of the design were built and deployed on various
skimmer boats and barges. (Exhibit 13. ) They were heavy,
crude and required power lift equipment to move them on or
off the boats, but they performed reasonably well.
Later in the operation, 10 additional circular weir skimmers
were built and added to the skimmer fleet. Their capacity
was slightly less than the AK design.
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While these makeshift products were successful in a sub-
stantial portion of the skimming at the Louisiana spill,
they are probably obsolescent already, for a great deal of
development work is going forward and improved designs will
certainly be available in the near future.
State of the Skimming Art
The problem of removing spilled oil has sparked the
imagination of many designers. By the summer of 1969 their
efforts seemed to fall into 5 approaches to the skimming
problem. During the Project, 22 skimmers were identified
in 5 design groups as listed on Exhibit 14 . Five of these
were tested in the Project. Seven others were inspected,
on display or in some form of demonstration. Information
on nine others was available in the form of literature and
reports.
1. The "separating" skimmers. (8)
This group included many variations of the adhesion
principle, wherein oil would preferentially wet an
endless belt or a rotating drum which operated partly
submerged in the oil.
2. The "blotter" skimmers. (3)
Several designers placed absorbent material in net
sacks which, in turn, could be dropped into an oil
spill to soak up the oil. When loaded to capacity,
the sacks could be withdrawn and either discarded or
wrung out and used again.
3. The "suction" nozzles. (3)
Suction hose nozzles operated from vacuum trucks have
been widely used when the trucks could be placed near
a spill.
Some are rigid, like a household vacuum cleaner nozzle,
and others are sufficiently flexible to conform to
some degree of wave action.
4. The "separating column" skimmers. (3)
These are barge - or boat-mounted devices for drawing
oil and water into an open-bottom hold or sump on
board a boat and allowing the oil to rise to the top
where it can be removed by suction, by a weir or by
a standpipe.
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5. The "floating weir" skimmers. (4)
These designs support a weir (either a straight line
weir or a circular weir) so that the intake (the top
of the weir) is floated below the surface of the area
to be skimmed. The weir is positioned as close to the
underface of the oil slick as possible, and the oil
and water together flow across the weir and into a
sump. A suction pump transfers the oil/water mix to
another tank for further separation.
(Note: In addition to the evaluation of 21 skimmers
listed above, project personnel developed and
tested an "articulated" skimmer which is
described in more detail later in this section.)
This project tested two commercial floating weir skimmers
and one experimental flexible suction nozzle skimmer. Two
endless belt designs were inspected, neither of which was
operating. A prototype of a floating skimmer with four
independently mounted weirs was also inspected and its
operation checked with other observers.
The skimmers in 1,2,3 and 4 above have been designed to
accomplish 100% separation of oil from water at the site
of the spill. With present technology this group of
"selective" skimmers is characterized by generally low
volume capacities and loss of efficiency in rough water
conditions. (The above statement based on reports from
equipment manufacturers in addition to observations made
on this project.)
It is undoubtedly desirable to work toward a high volume
skimmer which can separate oil and water efficiently at
the point of skimming but the achievement of this objective
may be some years away.
Consequently, a worthwhile short-term objective is that of
pumping a high volume of oil/water mix, always understanding
that every attempt should be made to keep the oil/water
ratio as high as possible. "Skim first and separate later."
The circular weir skimmer with adjustable rim which was
tested in many of our experimental spills has given firm
indications that its basic design in a larger size might
provide an immediate answer to this "interim" objective.
In smooth water tests it has performed with high efficiency
while pumping a thick oil spill. In test spills of small
volume such pumping action thins the film very quickly.
As a result the clean-up of a 100 gallon oil spill results
in pumping a high ratio of oil/water mix for only 5 or 6
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minutes during which time 75% of the volume of oil is
usually removed.
Clean-up of the remaining 25% of the spill requires 40 to
50 minutes during which time the skimmer is working at low
efficiency. During the final clean-up, some device must
be employed to move the skimmer to the remaining polluted
areas or the remaining pools of oil must be urged toward
the skimmer by moving the containment boom. (See Exhibit
6. )
There are other approaches to skimmer design which may
prove to have potential in meeting the interim objective
as well as the final objective as described earlier in
this section. However, the circular weir skimmer used in
this project performed so well in rough water (waves to
81 - 35 K winds) that a larger embodiment of that design
should provide a major increase in skimming capacity, and
multiple units could be effective in dealing with the
volumes of massive spills.
Design Problems of "Selective Skimming"
Referring again to the "selective" skimmers described in
1,2,3 and 4 above, emphasis on complete separation at the
point of removal creates more problems than it solves. In
this project it has been apparent that inclusion of the
separation function slows down the removal operation to
such an extent that most of these "selective" skimmers
are characterized by very low rates of production.
For example, the 3 "Separating Column" skimmers depend on
the tendency of oil to rise to the surface for their
ability to separate oil from water at the point of removal.
As pointed out previously, oil does not travel to the
surface instantly. Its rate of rise depends on the specific
gravity of the oil, size of droplets or globules, temperature
of sea water and other factors.
Rate of rise seems to have been overlooked by designers of
skimming equipment in some cases, and the time required
for that rise to the surface may become a limiting factor
on the rate of through-put for the equipment.
The inability to handle large volumes of oil,for whatever
reason, restricts a skimmer's attractiveness in combating
large oil spills simply because of the restrictions on
volume. However, the separating skimmers do have appli-
cation to small spills where volume does not go beyond
a few barrels.
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Furthermore, the complexity of the separating mechanism
creates operational problems as soon as operation is
attempted in choppy waves or in any situation where a
heavy ground swell is apparent.
It has also been apparent that any collection device fixed
rigidly to a boat or barge has limited ability to conform
to wave action.
In such cases, wave action which causes the vessel to rise
and fall even slightly may negate all the careful setting
of the skimmer at the proper level for efficient operation.
Whatever device is used for the adjustment of the weir or
intake nozzle, the plunging of a barge or vessel can lift
the skimmer completely out of the water or submerge it for
several feet below its optimum operating position unless
the skimming element itself is independently floated.
The endless belt design, of course, is a possible exception
to the above statement because the belt could be arranged
to travel through a wide range of wave heights. Even so,
the efficiency of pick-up on the belt itself might be
reduced appreciably due to the variation in the speed
with which any point on the belt would travel through
the relatively thin section of the oil slick.
Effect of Thick and Thin Slicks
All tests to date have indicated that it is far easier to
pump or skim effectively in a thick film of oil than in a
thin film. (See Exhibit 16. )
Most skimmers can pump oil effectively from a deep pool of
oil or from an oil slick 2" or more in thickness.
In considering the design of skimmers it should be kept in
mind that an oil spill is no-t a static situation. Left to
itself the slick continually changes size and shape while
the physical and chemical actions such as evaporation,
spread effect and other phenomena exert their influence.
This results in some spills being very thick near the
source, but rapidly becoming thin at some distance from
the source or after enough time goes by.
The high-volume skimmer used for attacking the thick spill
is much less efficient when working on a widespread slick
that has become very thin. One obvious approach to this
situation is to use booms to compact the slick. However,
such maneuvers take time which may not be available.
Therefore, there seems to be an opportunity to develop a
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new skimmer design which can travel fast enough to skim a
very thin surface film at a speed of 10 to 12 knots or
more and to sweep a relatively wide path in the process.
There are reports of a new design intended to sweep 120
acres per hour. This could be accomplished by a sweep
110' wide travelling at a speed of approximately 10 miles
per hour. A wider sweep would permit slower forward
speeds. Any combination which would skim 120 acres per
hour would be most welcome in dealing with the widespread
"iridescent" slick which is frequently associated with a
large spill.
It is evident, of course, that a selective skimmer, producing
100% oil at 100 gallons per minute would equal the production
of a non-selective skimmer producing 1,000 gallons of oil/
water mix at 10% efficiency. However, in a very thin spill
a selective skimmer would have to cover a lot of area to
contact 100 gallons of oil with its belt or drum. In a
thick spill, the problem would be easier for either type
of skimmer. Consequently, both approaches should be con-
sidered in further development efforts.
Design of an Articulated Skimmer (Exhibit 15 .)
At the start of this project the need for a successful
off-shore skimmer was apparent. The contract authorized
use of funds to construct a working model of any design
which showed promise of working successfully in rough water
(waves to 10') and high winds (to 35 Knots.)
Personnel employed on this project developed an initial
concept of an "articulated" skimmer, composed of 2 or more
sections hinged together but independently buoyant, so
that each section could ride up or down the front or
back of an ocean swell without effecting adversely the
operation of adjoining sections.
The "articulated" feature was tested successfully in waves
of 4' in height at several times during the project.
In addition to its ability to conform to wave profiles, the
skimmer was designed toward these objectives:
High volume through-put capacity - 500 gallons per
minute, or more, of liquid. (Either oil or oil/water
mix)
Readily portable by boat or aircraft.
Trouble free operation in rough water.
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Intake adjustable to thickness of slick.
Compatible with booms.
Capable of working in groups of three or more at a
time.
Initial construction and modification of the working model
was completed in March of 1970 and tested in one small,
experimental oil spill.
The skimmer was tested before that date without oil on
several occasions. In its experimental size it has demon-
strated a through-put capacity of over 250 gallons per
minute. It has maintained a uniform thickness of skimming
depth at speeds up to 2 knots while running over waves of
1 to 2 feet in height. The design may be worth additional
development.
In the final test the skimmer was used to pick up a small
oil spill. The down-wind end of a 50' diversion boom was
attached to one side of the "sluice" or entrance to the
skimmer. The up-wind end of the boom was anchored. Five
gallons of crude oil were spilled at the up-wind end of
the diversion boom. The resultant slick was eventually
50' long, (from the point of spill to the point of entry
into the skimmer.) The spill was urged toward the skimmer
by a 10K breeze, and the slick was held against the diversion
boom as expected by the force of the wind, being no more
than 2' wide at any point during its journey. (Exhibit 8 .)
As the floating oil entered the skimmer, the surface slick
and some sub-surface water passed over the entering edge
of the skimming blade which was set at a depth of 2" below
the surface. (Depth is adjustable.)
The oil/water mix then passed over the two articulating
hinges to a point where the paddle wheel pump elevated
the mix into a sump tank.
The sump was continually drained by suction pumps which
moved the oil/water mix into a floating tank where primary
separation of oil and water could take place.
The 5 gallon spill was cleaned up completely in less than
2 minutes after the slick reached the skimmer.
The skimmer has been described in detail on Invention Dis-
closure Forms which have been forwarded to the Contract
Officer as required.
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Pumps and Accessory Equipment
Several of the skimmers studied in this project depend on
standard commercial pumps and hoses to move the oil/water
mix away from the point of skimming and into the next tank
or conduit in the system.
When such skimmers are floated independently of their pumps
there are two potential problems which should be considered
in future design of skimmers.
1. The connecting hose must be flexible
a. To allow the skimmer to float on the surface
without impeding the skimmers ability to match
the contour of the waves, and
b. To pass over, under or around any booms or
other equipment which may be located close to
the skimmer.
2. The hydraulic head between skimmer and pump must
be kept as low as possible to minimize priming
problems and to insure maximum efficiency of the
pumping.
Self-priming pumps are desirable at initial start-up of
operations, but the ability to pick up prime following
periods of temporary loss of prime is essential. In any
sort of rough water operation, a skimmer will surely
encounter wave action which temporarily starves the intake,
and the pump must be able to pick up its prime and keep
going without the necessity for shutting down and repriming
manually.
From the discussion above, it is evident that a selective
skimmer mounted on a boat or barge with all its connecting
equipment combined into one system of containment, removal
and some storage capacity, is in itself a complete system.
When a skimmer is limited to the removal function and must
be combined with other equipment from other designers,
compatibility with that other equipment is very important.
Designers should make every attempt to insure that their
skimmers are indeed able to function as an effective part
of a complete system.
Conclusions and Recommendations
Conclusions
1. Improved skimmer designs are needed:
a. For rough water operations
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b. For high-speed pick-up of thin oil slicks
spread over wide areas.
2. For massive oil spills, a through-put of 500 gpm
or more is needed.
3. Most versatile design at time of this report seems
to be the circular sump with a fixed or adjustable
weir.
4. The endless belt "separating" skimmers have good
potential for small spills in protected waters.
5. Dependable pumps, motors and accessories are
essential for good skimming operations.
6. The skimming process, by itself, will not generate
a surface flow of oil for any great distance. 6'
to 10' seems to be the maximum at present.
7. The skimmers must go to the oil, or the oil must
be brought to the skimmers.
8. Skimmers should have a high degree of compatibility
with all other units in the system.
Recommendations
1. The development of improved skimmer designs should
be accelerated until there is high volume capacity
at strategic points near all petroleum centers.-
2. One major objective is the skimming of massive
spills in rough water conditions.
3. Another objective is the skimming of very thin
slicks spread over wide areas.
4. Optimum performance toward these two separate
objectives may require the use of dis-similar
skimming principles.
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RECLAMATION AND DISPOSAL EQUIPMENT
Oil/Water Ratios and the Recovery System
Whenever an oil spill is skimmed from the ocean, some
system must be provided to store, transport and dispose
of the oil involved.
Hopefully the ultimate destination of the skimmed oil
will be a refinery which can process the recovered oil
and reclaim it to the point that it can be turned back
into industry and its economic value can be realized.
Somewhere between the ocean and the refinery, water must
be separated from the oil to make the oil acceptable to
the refinery process.
If an efficient "separating" skimmer is used initially,
the separating is accomplished at the site of the spill.
From that point on nothing but the oil need be put through
the storage, transport and disposal system.
If a separating skimmer produces a mix of 90% oil to 10%
water the liquid quantities downstream of the skimmer will
be far smaller than with an ratio of 10% oil/90% water.
Under those circumstances the problem of transporting and
disposing of the oil can be solved by any conventional
method used for transporting petroleum liquids. This
includes the use of drums, pipelines, tanker barges,
portable tanks, or floating tanks. Such items are generally
available in good quantity in the areas where petroleum is
being handled.
From discussion in the previous chapters it will be seen
that with th'e present state of the skimming technology wide
spread use of separating skimmers is not forecast at an
early date. Such use as is realized will probably be on
small operational spills in relatively calm waters and
will yield small volumes of oil to be transported.
In spills which involve substantial quantities of oil,
(50 barrels and more) the probability is high that non-
separating skimmers will be used for some time to come,
and the oil/water mix emerging from those skimmers will
have a much lower oil/water ratio, probably in the range
of 20% oil to 80% water.
When a large spill is handled by non-separating skimmers,
the total volume of the oil/water mix may be large enough
to pose a handling problem. Therefore it is important
to perform some separation of the oil from the water at
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the earliest possible point in the system.
There was no separating skimmer available to this project.
Skimmers tested delivered oil/water mixes as low as 5%
oil. Two variations of a system for separating, reclaiming
and disposing of the recovered oil were used. Each of
these systems included the use of gravity separation. With
smaller amounts, (spills of 50 gallons and less) it was
possible to use a gravity separator tank on shipboard.
When larger amounts were involved a floating tank was used
as a gravity separator during transportation of the oil/
water mix from ship to shore and a secondary gravity
separator was mounted on the docks alongside the testing
area. In either case, the intent was to achieve some
separation as early as possible in the process so that the
separated water could be drained overboard and the total
volume of liquid handled beyond that point could be mini-
mized. (Exhibit 17. )
Details of each of the above systems follow.
Shipboard. Separation Systems Used in the Project
In the early stages of the project when oil test spills
were very small (less than 20 gallons per spill) it was
possible to use a very small but effective separating
system mounted on the work barge.
A 280 gallon household fuel oil tank was skid-mounted and
placed in the working area of the barge.
Oil/water mix pumped from the skimmer was delivered
directly into the tank which was mounted in a vertical
position as shown in Exhibit 18
Because the quantities of oil spilled were very small
(20 gallons or less) the oil/water ratio was expected to
be about 10% oil/90% water by the time the oil/water mix
reached the tank. Under those circumstances the capacity
of the tank would be barely sufficient to contain enough
oil/water mix to clean up all of the spill and in some
cases a two batch process was planned.
On the first tests, however, gravity separation inside
the 280 gallon tank was taking place far more rapidly
than had been expected. This was true even though the
oil/water mix had been pumped into the tank through an
impeller type centrifugal pump which emulsified the oil.
Nevertheless the oil did separate rapidly so that it was
possible to drain clear water from the bottom
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of the tank after the tank was about half full.
This accelerated procedure was sufficiently effective to
accumulate the separated oil from 3 or 4 spills before it
was necessary to empty the contents of the tank into a
storage container on shore.
This type of system would be satisfactory for many of the
small operational spills which are encountered in a harbor
and a ship-mounted tank of even 500 gallons capacity could
provide adequate capacity to hold the oil from many of the
small spills encountered.
Floating Tanks as a Separating System
When the project had gone forward to the point of making
larger oil spills (100 gallons per spill) it was evident
that the 280 gallon capacity of the barge mounted tank
was insufficient for a continuous operation.
The possibilities of using a floating fabric tank for the
storing, transporting and perhaps separating of substantial
quantities of oil/water mix had been noted.
The Needham office of the FWQA found a fabric tank of
5,000 gallon capacity and arranged to make it available
for use on the project.
This particular tank was not designed for marine use.
Necessary modifications included auxiliary flotation,
inlet hoses, discharge hoses and an air vent so it could
be used with skimmer pumps and transfer pump equipment.
Equipped with this tank (See Exhibit 19-20), as much as
5,000 gallons of oil/water mix could be pumped directly
from the skimmers into the floating tank.
Here again gravity separation of the oil and water made it
possible to start draining clean water from the bottom of
the tank 30 or 40 minutes after the pumping started.
In those instances wherein 3 or 4 thousand gallons of mix
were pumped into the tank and then towed to shore, primary
separation was well underway when the tank arrived at
dock-side. When the clean water had been drained the
residue in the tank was 80% oil or better.
At this point the contents of the tank were discharged into
vertical separator tanks mounted on the dock alongside the
testing basin. (See Exhibit 18.)
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Each tank held 1,000 gallons. A settling period of one
hour was sufficient time in these vertical tanks to
achieve sufficient separation so the clean water could
be drained off. The residue in the tank was useful oil.
This oil was re-used for oil spill purposes but it could
well have been returned to a refinery for complete
reclamation.
From the description above it will be seen that there is a
vast inventory of equipment which can be readily pressed
into service for use as components of an oil handling,
separating, transporting and storage system. Some of
the items which are available in most areas for this type
of work include:
a. Drums or other open containers. (55 gallon capacity)
b. Skid-mounted tanks of almost any size (200 gallons
and up) or shape which have adequate openings at
the top to receive the oil and workable drains near
the bottom for discharge.
c. Metal and fabric pipes and hoses of all sizes and
styles with their appropriate valves and fittings.
d. Pumping equipment as required.
Incineration of Sludge Wastes
In any refinery operation there develops a sludge which
cannot be used industrially. Various methods are used
for disposing of this. Some refineries have burning pits
where the sludge is periodically disposed of by incineration.
Considerable improvement can be made in the incineration
process and this is discussed in the following paragraphs.
Now that air pollution is a matter of prime importance,
some careful attention should be given to the use of
equipment whereby pollution of the air is avoided when
incineration must take place.
There are two or three equipment suppliers who manufacture
highly efficient oil burners which might accomplish this
type of incineration without generating air pollution.
There are reports that such burners have been installed in
paper mill dryers where the products of combustion went
directly into the drying of white paper and were so
effective that there was no visible evidence of any par-
ticulate matter adhering to the paper produced under those
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circumstances. The type of burner described above has
been on the market for over 15 years, its operation is well
understood and the burners are highly reliable under a
wide variety of industrial applications.
This is the logical avenue to explore for the incineration
of large quantities of sludge oil or, in some cases, for
the disposal of quantities of recovered oil when those
quantities are too small to justify transportation to a
distant refinery.
It is conceivable that the high-efficiency burners described
above could be mounted effectively on ship-board and
operated at the site of an oil spill if it became desirable
to do so rather than to attempt transportation of the
recovered oil.
Addresses of the manufacturers of this equipment and
additional technical information are available upon request.
Alternate Waste Disposal Methods
The problems of disposing of sludge oil by other than
incineration are apparent and should be well known by
anyone active in the petroleum industry.
Burying oil or pouring it on a dump or burning it by
conventional methods are less than satisfactory answers.
In some areas there are companies which collect sludge
oil, used crankcase oil and other contaminated oil products.
This waste oil can be used satisfactorily on industrial
roads or areas where some sort of surface treatment is
required to support wheeled traffic.
If underground disposal must be made, careful selection
of the site minimizes the problem of leaching of oil into
water systems or other areas which should not be contami-
nated. The site must be chosen with great care and with
full attention to any regulations governing underground
disposal which might apply in the area.
Conclusions and Recommendations
Conclusions;
1. In any system of oil recovery and disposal, primary
separation of the oil from the water should be
introduced as early in the system as possible
so that the problem of handling large
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volumes of oil/water mix is minimized.
2. Under most conditions, and with most types of
oil, the gravity separation system is so simple
and dependable that it should be given first
consideration.
3. When and if shipboard separators (such as centri-
fuges or other techniques become available), such
equipment should be introduced into the system at
the earliest possible point to reduce the volume
of liquid to be handled.
Recommendations
1. The ultimate objective of the recovery and disposal
system should be to deliver the largest possible
quantity of reclaimable oil to an oil refinery
which can receive it.
2. The use of high pressure and high efficiency oil
burners should be explored as a method of ultimate
disposal of non-reclaimable oil sludges.
3. At the present state of the art, the design and
operation of equipment to receive oil from the
skimmer pumps and to handle it through ultimate
disposal will depend on the type of equipment
which is available at or near the location of
the spill. In most areas where oil is being
handled or transported in any volume, there is
probably an adequate inventory of pumps, piping
equipment, valves, tanks, and other accessories
which can be mounted on surface craft or assembled
at strategic shoreside locations so that systems
such as described above or variations of them can
be put together and operated effectively.
4. It is suggested that attention be given by govern-
ment and industry to providing large fixed and
specifically designed shore-side separator units.
Vessels carrying petroleum products could then tie-
up at place of loading and discharge the remaining
ballast into separator tanks rather than discharging
ballast into the sea. These units would be strate-
gically placed at loading points.
(Note: This type of installation was called for
in a Presidential message delivered on May
20, 1970.)
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THE "SYSTEMS" APPROACH
Outline of a Complete Clean-up System
This Section of the report is written to emphasize the
need for a "Systems" Approach in dealing with oil spills.
Obviously, prevention, of oil spills is the ultimate answer
to the problem, but until prevention is 100% effective,
there must be a clean-up capability to minimize the damage.
A complete clean-up system begins with the make-ready
activities of organization, equipment procurement, training
and their sub-divisions. The actual removal of oil from
the spill begins with the detection of the spill and
follows a sequence of events leading to final disposal of
the spilled oil and make-up of the equipment in preparation
for re-use.
Testing and evaluation of equipment on this project, has
emphasized the requirement that each unit must be compatible
with other units to form a complete system.
For example, it should be possible to fasten a mechanical
barrier to a skimmer so that no oil can leak out at the
joint. A skimmer pump must be able to deliver its discharge
high enough and far enough to reach a tank on the deck of
a barge or on a dock. The tank, in turn, must be an effective
unit in a separating or disposal system.
A thorough understanding of the inter-dependence of units
will benefit personnel responsible for all phases of
preparations, training, planning the attack on a spill
and operation of the equipment as well as those who design
and manufacture equipment for oil spill control.
The inter-relationships effecting each phase of the
operation are complex. Consequently, the balance of this
Section reviews all stages of the process and points out
some of the instances where the success of one unit depends
on the proper operation of the unit which precedes or
follows in the sequence.
The make-ready activities of organization, equipment
selection, procurement, and the training of personnel
are outlined in Appendix D entitled "Community Response
to the Oil Clean-up Challenge".
In addition, Appendix A contains detailed reports on
several special projects wherein the inter-dependence of
various phases of the operation and the value of the
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Systems Approach should be readily apparent. .
It is obvious that whenever the prevention part of the
program fails, the clean-up system operates until eventual
disposition has been completed and the equipment is ready
for re-use.
The various stages of the clean-up program include:
1. Detection
2. Location
3. Analysis
4. Containment
5. Compaction
6. Removal
7. Storage, Separation and Sludge Disposal
8. "Make-up" of Equipment
Equipment and facilities needed for each stage of the
operation are described in other Sections of this report.
Good equipment is already available for some portions
of the operation, new developments are known to be under-
way, and new approaches to some of the problems will appear
at an increasing rate as new research is focused on this
situation.
Detection
This section should really be entitled "Spill Alarm".
This term is suggested to emphasize the need for rapid
action just as in the case of reporting a fire. It is
unfortunate at the present time that oil spills are not
so considered. Many oil spills go unreported for days
or weeks although they may have been observed by many
personnel who could have reported their presence had
the urgency been understood.
Many oil handling activities are prompt and conscientious
in reporting oil spills.
Nevertheless, in the open waters or along sections of the
coast which are sparsely inhabited spills may remain
unreported because no immediate economic danger is recog-
nized and the observer may hope the problem, if ignored,
will disappear.
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Crews on commercial vessels of all categories should be
alert by now to the potential danger of an oil spill.
Many other groups, however, have not been told where to
report spills so that active counteraction can be started.
Coast Guard Bases are an obvious communication center.
In addition, the harbor master or the local fire department,
yacht clubs, power squadrons, city officials, bridge tenders
and many others constitute an increasing network of
knowledgeable persons who know how to "ring the alarm" in
a particular area.
The reporting of oil spills from the air can be very
effective but very little has been done to alert pilots
of private, commercial and military aircraft to the need
of reporting oil slicks; All commercial and most private
aircraft are in almost constant communication with FAA
radio stations. This provides a very effective channel
for initiating the oil spill alarm. (See Appendix A. )
At the time of this report, there is no satisfactory method
for detecting oil spills promptly during the hours of
darkness. Research has been initiated and proposals for
development range from continuous inspection by visual
means to improved photography from satellites in space.
Inasmuch as time is extremely important in the early
stages of an oil spill it would seem that attention to
this problem of reporting should receive high priority
for intensive research.
Location
Just as in reporting a fire, accurate location of the
spill is of extreme importance in the first report.
Given the infinite combinations of water conditions,
terrain, wind, weather, tide, size of the spill and the
type of material spilled, the need for accurate location
is evident.
Even this is only a part of the problem because oil spills
travel across the surface of the water under the influence
of tidal currents and surface winds to such an extent
that their change of position is of continuing concern
and the prediction of the course is difficult.
When one understands the time required to marshal the
clean-up force and equipment, the importance of tracking
a reported spill becomes self-evident.
A recent spill near an oil terminal in Portland Harbor,
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Maine occurred just after midnight when visual observation
of the extent of the spill and its track was almost
impossible.
In this instance, the placing of an oil boom was prompt
and, under the circumstances, extremely effective. Never-
theless, some portions of the spill had drifted outside
the area surrounded by the boom and it required prompt
action by a local helicopter to find these other patches
of oil early the following morning before they impacted
on sensitive areas in the nearby harbor.
If an oil spill followed the known tidal currents in the
area an application of dead reckoning calculations would
be most helpful in predicting the track of an oil spill.
However, local surface winds can push an oil spill against
tidal currents and at surprising speeds. This makes it
important to know the local weather conditions in more
detail.
Improved forecasting of the track of a spill, plus good
communications, would make the job of getting to the spill
much easier and would save precious time.
Analysis
The volume which has been spilled and the type of oil is
also very important to the planning of effective counter
measures.
A spill of highly volatile oils may yield to the evaporation
process and disappear completely into the atmosphere under
some circumstances. Off-shore, such a spill might simply
be ignored while nature takes it course, while the same
spill in a harbor area might be a serious fire hazard
calling for immediate clean-up effort.
In any event every detail of the spill is important to
the individual who is responsible for marshalling the clean-
up activities and directing the personnel involved or for
alerting shore installations which might be threatened by
an approaching oil slick.
Characteristics of an oil spill vary over wide ranges and
cannot be determined accurately without close inspection.
The type of oil, the thickness of the oil film, temperature
of the water and other items can best be determined by
surface inspection methods at present.
It might be worthwhile to develop a technique for extracting
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a sample from the central area of an oil slick by some
application of a pick-up device operated from a fixed
wing or rotor wing aircraft. At many locations such
technology could provide critical information much faster
than by surface methods.
Containment
Containment of an oil spill by means of a surrounding
barrier is a key operation in preventing the continued
spread of the spill over a wide area and perhaps in
limiting or controlling the movement of the spill under
the urging of wind and current conditions.
The same equipment which is used to contain the spill may
also prove to be useful in compacting the spill as part of
the preparation for the removal process.
Unfortunately, many of the mechanical booms have not been
designed to work effectively as a component in a system pri-
marily because other components of the systems are them-
selves still in a formative stage.
As a result mechanical boom "A" may be awkward and difficult
to handle in connection with oil skimmer "B".
Compaction
Compacting of an oil spill is the process of gathering
the edges of the spill toward the center so that the thick-
ness of the oil film is increased.
Compaction will sometimes be accomplished by maneuvering
a boom or other type of barrier so that the enclosed area
is gradually reduced. Under most circumstances it may
be accomplished by action of the underflowing current or
by surface winds.
The advantages of compaction are evident because most oil
removal equipment functions more rapidly and more efficiently
in a film 1/2" thick or more but the efficiency deteriorates
rapidly as the film becomes thinner.
Consequently, designers of barrier equipment should give
more attention to the ability to compact a spill. The
boom or barrier should control the spilled oil in a manner
to provide good working conditions for the skimmer and the
boom should never become an obstacle to the successful
operation of the skimmer.
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Removal
Skimming equipment has been discussed in some detail in a
previous Section. Many new skimmer designs are well along
in the development stage or are being offered to the trade
as finished equipment.
While some of the skimmer designs include components for
containment, removal, and storage functions, most skimmers
are limited to the removal function and must team up with
other equipment to be useful.
In either case, the Systems Approach suggests that skimmers
should be compatible with the equipment which precedes them
or follows them in the clean-up process. Designers and
manufacturers should work constantly to make their equip-
ment and supplies function as an effective part of the
complete system.
Storage, Separation and Sludge Disposal
In the removal process some type of storage must be pro-
vided.
In all but the smallest slicks, it is probable that more
storage capacity will be required than can be provided in
the vessel which carries the removal equipment.
Storage capacity may be combined with separation facilities
whether on board ship or ashore. For example, any tank
which is equipped with a drain valve near the bottom can
be used for gravity separation of oil from water. Such
a tank might be the hold of a tanker vessel or the hold
of a barge or a tank available in a nearby shore install-
ation.
Sludge is generated at the separating tanks, and some
provision must be made for its disposal. Incineration
equipment is recommended as described in the Section on
Reclamation and Disposal.
"Make-up" of Equipment
The final stage in any clean-up is to prepare the equip-
ment for the next use.
This can be an arduous task requiring costly hand labor
unless the equipment supplier has designed for easy
cleaning and storage. Attention should be given to powered
cleaners or other accessories which facilitate the cleaning
process.
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Cleaning should be accomplished in an area which can
contain the oil and other pollutants removed from the
equipment. Waste from the cleaning operation must not
be allowed to drain back into the ocean, thus becoming
a secondary source of pollution.
In either event, the Systems Approach dictates that this
final problem be given proper attention.
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Acknowledgments
Thanks and sincere appreciation are extended to the
following groups for their support, encouragement and
assistance in this project.
To all those members of the Portland Harbor - Casco Bay
community in Maine, the Fire Departments of South Portland
and Portland, civic officials, the Portland Pilots, marine
supply and repair firms, and many individuals and
companies who were generous in loaning equipment.
To the South Portland Base of the United States Coast
Guard for its complete cooperation, constructive
criticism and assistance when needed.
To the oil terminal operators in the Portland Harbor and
Casco Bay areas, the Chevron Oil Company Division in
Louisiana and to the many representatives of the major
oil companies who visited the project, supplied valuable
information and loaned equipment.
To the many equipment suppliers who offered equipment for
testing purposes and welcomed the give and take of an
evaluation program.
To the FWQA offices in Washington, D.C., Edison, New Jersey,
Needham and Boston, Massachusetts, and especially to Mr.
Thomas W. Devine, the Grant Project Officer.
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BIBLIOGRAPHY
"Study of Equipment and Methods for Removing Oil from
Harbor Waters"
By: Paul C. Walkup
Battelle Memorial Institute
Richland, Washington
For: Naval Civil Engineering Lab.
Department of the Navy
"The Containment of Oil on Water and Its Removal"
Aransas, San Patricio & Nueces Counties, Texas
Study & Contingency Plan - April, 1970
"The Ocean Eagle Oil Spill"
By: M. J. Cerame-Vivas
Puerto Rico University
Mayaquez, Puerto Rico
For: F.W.Q.A.
"Oil and Hazardous Materials Contingency Plan for Pre-
vention, Containment and Clean-up for the State of Maine'
By: Portland Harbor Pollution Abatement Committee
Portland, Maine - January, 1970
"Proceedings of the JointConference on Prevention and
Control of Oil Spills"
By: API
F.W.Q.A.
At: Americana Hotel
New York - December 15-17, 1969
"Proceedings of the Marine Frontiers Conference"
University of Rhode Island
July 27-28, 1967
"Oil Pollution: Problems and Policies"
By: Stanley E. Degler
Environmental Management Series
Bureau of National Affairs - 1969
-73-
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"Oil Spillage Study"
Literature Search and Critical Evaluation for
Selection of Promising Techniques to Control
and Prevent Damage.
By: Pacific Northwest Laboratories
Battelle Memorial Institute
For: Department of Transportation
U. S. Coast Guard - November 20, 1967
"Our Nation and the Sea"
By: Commission on Marine Science and Engineering
Resources
American Association of Port Authorities
"Reducing the Spread of Oil Spills at Sea"
By: James A. Pay
M.I.T.
At: Symposium on the Scientific and Engineering
Aspects of Oil Pollution of the Seas
Woods Hole Oceanographic Institute - May 16, 1969
"Review of Oil Spill Clean-up Techniques and Experiences"
By: F. H. James, Jr.
Gulf Oil Company
Port Arthur, Texas
At: Session on Air and Water Conservation
API Division of Refining
Palmer House
Chicago, Illinois - May 13, 1969
"The Spread of Oil Slicks on a Calm Sea"
By: Prof. James A. Fay
Fluid Mechanics Lab.
M.I.T. - August, 1969
"Laboratory Guide for the Identification of Petroleum
Products"
Pub. by: F.W.Q.A.
Division of Water Quality Research
U. S. Department of Interior - January, 1969
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"Containment and Collection Devices for Oil Slicks"
By: David P. Hoult
M.I.T.
At: Symposium on the Scientific and Engineering
Aspects of Oil Pollution of the Seas
Woods Hole Oceanographic Institute - May 16, 1969
"Oil Skimming Devices"
Edison Water Quality Laboratory
F.W.Q.A.
U. S. Department of Interior - May, 1970
"Exercise Torrey Canyon"
U. S. Coast Guard
Portland, Maine - April, 1968
"Industries Program to Improve its Oil Spill Clean-up
Capacity"
By: L. P. Haxby
Mgr: Environmental Conservation Department
Shell Oil Company
At: 21st Annual Pipe Line Conference
API Division of Transportation
Statler Hilton Hotel
Dallas, Texas - April 13-15, 1970
"An Evaluation - Oil Spill Control Equipment and Techniques"
By: E. A. Milz
Research and Development Lab.
Shell Pipe Line Corp.
At: 21st Annual Pipe Line Conference
API Division of Transportation
Statler Hilton Hotel
Dallas, Texas - April 13-15, 1970
"The Use of Coated Fabrics in Containment of Petroleum"
By: Richard T. Headrick
Firestone Coated Fabrics Co.
At: API Meeting
Lakewood Country Club
Los Angeles - September 11, 1969
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"Burning of Oil Slicks"
By: Paul R. Tully
Cabot Corp.
At: Symposium on the Scientific and Engineering
Aspects of Oil Pollution of the Seas
Woods Hole Oceanographic Institute - May 16, 1969
"The Role of the Federal Government in Controlling Oil
Pollution"
By: Max Edwards
U. S. Department of Interior
At: Symposium on the Scientific and Engineering
Aspects of Oil Pollution of the Seas
Woods Hole Oceanographic Institute - May 16, 1969
"The Dynamics of Film Formation"
By: P. C. Blokker - 1964
"In the Wake of Torrey Canyon"
By: Richard Petrow (1968)
"Oil and the Maine Coast"
By: Natural Resources Council of Maine
116 State Street
Augusta, Maine - March, 1970
"Water Pollution by Oil Spillage"
By: Science Information Center
Southern Methodist University
Dallas, Texas 75222
214EM3-3011 (November, 1969)
An excellent survey of 11 indexes and catalogs of
scientific treatises. Available through February
1, 1969. Page 57 (Volume II) contains detailed
reference to New York Times reporting of Santa
Barbara spill.
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Appendix A
SPECIAL PROJECTS
There are many occasions in a clean-up operation wherein
an improvement in one part of the operation could con-
tribute to the success of another part. The following
paragraphs describe several such occasions encountered
in this project where the "Systems Approach" can produce
a synergistic reaction.
Aerial Reporting of Oil Spillj
Since 1967 there have been several instances of oil spills
in remote areas of the Maine Coast which have gone undetected-
or at least unreported-for several days. Several such
spills have been found eventually and reported to the
Coast Guard, but the chances of determining the cause and
responsibility after such delay are quite remote.
Over the same period of time, there have been several spills
reported to personnel of this project wherein the pilot or
passenger in an aircraft has been able to observe and
report a spill.
Repeated instances of effective reporting have confirmed
the feasibility of aerial observation of oil slicks. The
Annual Report on this project, dated October of 1969, noted
this circumstance. It also noted that there was then no
established procedure for reporting such observations to
a communications network which would pass the word to the
Coast Guard or to other authorities having the know-how
to start the ball rolling on clean-up operations.
The circumstances described above were related to F.A.A.
Air Traffic Control personnel at the Portland, Maine
International Jetport and to the Commanding Officer of
the U. S. Coast Guard Base in South Portland, Maine, in
September, 1969.
FAA personnel confirmed that pilots of itinerant aircraft
(Military, Airline or General Aviation) were in frequent
communication with Flight Service Stations or Air Traffic
Control Centers and that reports of oil spill situations
could be transmitted to those facilities and then relayed
to the Coast Guard.
Development of this procedure into a viable system would
not require new equipment or technology, although some
publicity and guidelines for such reporting would be
helpful.
A suggested plan for the system is included as Exhibit 21.
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Coast Guard personnel in South Portland, Maine, indicated
a willingness to receive such reports, screen them and
take appropriate action. The Commanding Officer empha-
sized that the ability to receive early notification of
bonafide spills was so important that it would outweigh
the inconvenience of an occasional false alarm or dupli-
cate reports on spills already reported.
As this report is written, a press release dated October
13, 1970, (Boston, AP) quotes the Commander of the First
Coast Guard District in Boston as asking that airline and
other pilots, police and persons who travel along the
coastlines be alert to spot oil spills and to report
them.
Widespread adoption of an aerial reporting system along
the lines described above would improve the operation of
detecting an oil spill with minimum delay and this, in
turn, would accelerate the subsequent clean-up operations.
First Echelon Chemical Analysis
In many oil spill situations, it is desirable to analyze
samples of the oil to determine its chemical content,
its viscosity and the thickness of the slick.
In situations where the source of the spill is unknown,
analysis of the spilled oil may lead to eventual identifi-
cation of the source so that responsibility for the spill
can be determined accurately.
The core-sampling technique which was developed as part
of the testing technology of this project is described
in an earlier Section of this report and is illustrated
in Exhibit 1. While the equipment used was crude and
was operated from a surface vessel, the procedure was
satisfactory for obtaining a rough measure of the thickness
of the slick. Further development of the technology might
permit samples to be taken from aircraft. Such samples
would not only measure the thickness of the slick, but
would provide a sufficient quantity for chemical analysis.
This would be useful in dealing with a mystery spill,
particularly if it were found at some distance from the
nearest shorebased clean-up facility.
Facts derived from analysis of samples would assist in
the effective planning of clean-up operations and the
dispatching of most suitable equipment to a distant spill.
Oil Slick Warning Systems
Experience in Portland Harbor has indicated a definite
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need for a means of advising the boating community when-
ever oil pollution is present in local waters.
Various types of warning systems are being considered,
including sound signals, light signals or a distinctive
pattern of floating buoy which could be anchored in or
near a polluted area. (See Exhibit 22 .)
Air Born Command Post for
Coordination of Anti-Pollution Efforts
In all activities of a clean-up effort it is evident that
the tracking of the slick and the proper position of
boats, booms and other equipment can best be coordinated
from an elevated observation point.
In rough water tests in Portland Harbor we observed from
a position on the pilot house of the Portland Fireboat,
or from the flying bridge of a Sport Fisherman. Such
location, 20' or 30' above sea level provides a great
advantage over a position on a work boat at sea level.
Exhibit 23 .
These conclusions have been made known to the Maine Port
Authority. That organization has just completed a heli-
port on the roof of the Maine State Pier. This provides
a base from which to operate the helicopter which is
occasionally used as an air born observation point when
an oil spill is being attacked at some distance.
Systems Test Combined with
Photometric Test - October 9, 1969
OBJECTIVES - This test had two objectives as follows:
1. To demonstrate that proper booming technique could
contain the oil spill on the surface of the water
and move the spill to another location where clean-
up operations could be completed.
2. To determine the efficiency of photo measurements of
the spillage, containment and clean-up of a 100 gallon
spill.
PROCEDURE - Photo measurements of the results were taken
from an airplane flying at an altitude of 800' over the
site of the spill. The plane was equipped with specialized
photo equipment supplied by Singco Corporation and operated
by Singco personnel.
Physical measurement of the spill was taken by project
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personnel. Time logs, colored photos, observations and
chemical measurement of core samples collected during
the test were included.
PREPARATION - A coordinated schedule for air and ground
operations was prepared and reviewed with all personnel.
AMBIENTS - The test was conducted outside of the testing
basin at South Portland, Maine. Wind northwest at 6
knots, sea calm, tide falling, current at the spill site
was south to north.
The time log of the experiments contained the following
entries:
11:50 a.m. Singco plane arrived at Portland Airport.
Equipment deployment had been completed at the test
site.
12:55 p.m. Plane arrived overhead at the test site.
1:02 p.m. Started spill procedure.
1:34 p.m. Two 55 gallon drums of oil had been emptied
into a floating pen formed by a light fence type boom
rigged into a pen approximately 40' on a side and towed
behind the work barge.
1:37 p.m. The oil slick had covered the area inside
the pen completely.
1:50 p.m. The pen was moved very slowly to a position
about 200' off the pier head. During this movement of
the pen with the oil contained inside, any relaxing
of the tension on the tow points of the boom allowed
the boom to sag so that a few pints of oil escaped
over the top of the boom. Improvement in towing
technique could have avoided this loss. (Exhibit 6 .)
2:05 p.m. The oil spill was uniform throughout the
extent of the boom and the first core sample was ex-
tracted for laboratory measurements.
2:10 p.m. Skimming procedure was started. The skimming
pump was operated at idle speed so that a thin skim
could be extracted.
2:15 p.m. A core sample was extracted for laboratory
measurement. At this point it was established that
the wind was pushing the slick toward the south end
of the enclosure. This effect plus the rapid removal
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of oil by the skimmer caused large clear spots to
appear over about 1/3 of the enclosure area. The
pump was still running at idle speed but it was be-
ginning to pump some water along with the oil.
2:25 p.m. Core sample No. 3 was extracted.
2:40 p.m. Core sample No. 4 was extracted. At this
point 2/3 of the enclosure was clear of oil.
2:45 p.m. At this point the contour of the pen was
changed so that the light breeze could clean out oil
spots in corners of the pen protected from the wind
by the freeboard of the boom. This maneuver was
effective and the remaining oil moved immediately to
the downwind side of the pen where the skimmer was
operating.
2:55 p.m. At this point the skimmer was operating in
a very thin film of oil and was producing a low oil/
water ratio. Only two or three square feet of spill
remained to be cleaned.
3:07 p.m. Clean-up completed.
3:10 p.m. Core samples No. 5 and No. 6 were extracted
for laboratory analysis to determine effectiveness of
the clean-up.
3:35 p.m. Output of the skimmer had been pumped into
a floating tank. The tank was now towed to dockside.
In the process, it served as a primary separating
tank as well as to transfer the oil residue to
separating tanks on the shore.
3:50 p.m. The boom was collapsed and towed to dockside
and stowed.
Commentary on the Tests
The first objective of the test was realized. The 100
gallon spill was held satisfactorily inside a containment
boom (a light fence type), towed a distance of more than
200' without unavoidable loss and cleaned up satisfactorily
at the new location. Similar technique would be useful
in moving a spill of .fuel oil or other combustible substance
away from a dangerous location before starting clean-up
operations.
The second objective was partially completed. Pictures of
the entire operation were taken at intervals of about 5
minutes from an elevation of 800 feet. Photo equipment
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was mounted in a Cessna 172 aircraft which flew a rec-
tangular pattern over the test site. Infra-red film, Tri
X Pan film and Kodachrome II were tested. The Kodachrome
II was lost enroute to the developer, but prints of the
Infra-red and Tri X Pan film were clear. (See Exhibit
27 .)
The black and white prints showed excellent definition of
the oil coated areas of the water at all stages of the
operation. When a small amount of oil escaped from the
boom (perhaps 1 quart volume) the very thin, iridescent
slick outside the boom was hardly noticeable from the
surface, but the Tri X Pan film showed that slick escaping
from the boom, spreading out into a streamer about 20 feet
long by 3 feet wide and gradually changing position under
the influence of wind and tidal current.
A more detailed report on the film technique was made by
Singco Corporation. The complete text of the report is
included as received. (Appendix F .)
Disposal of Oil/Water Mix
The oil/water mix removed from the boom on October 9th
remained in the 5,000 gallon floating tank for 5 days. On
October 14th transfer of oil to the separating system on
the dock was started.
Initial draining from the tank was completed in about 15
minutes of full throttle pumping. During this time clear
water was being pumped steadily. When the first trace of
oil appeared the output was pumped into the 2,000 gallon
separating tanks on shore. The volume remaining in the
fabric tank at the time of the switchover was estimated
at 150 gallons of oil/water mix. It required only two
minutes pumping time to transfer it to the shore tanks.
Within six hours the final separation of the oil from the
water had taken place in the vertical separating tanks on
the dock.
Funnel Boom Test
In February of 1970 a special test was arranged to determine
the ability of two booms, towed independently, to produce
a "funnel" effect and to channel oil into a skimmer towed
at the small end of the funnel.
Equipment included two tow boats, two light fence booms,
each 160 feet long, the articulated skimmer prototype (as
developed on this project (See Exhibit 23 .) pumping equip-
ment and a 5,000 gallon floating fabric tank. The Portland
Fire Boat served as a headquarters and observation post.
(See Exhibit 23 .)
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Tow tests were conducted in Portland Harbor on calm seas
with occasional waves from passing vessels. There were
many small pieces of ice floating on the surface. Towing
speed was 1% to 2K.
Results of the test were as follows:
a. With the tow boats 200' apart as in Exhibit 24 ,
the funnel collected far more surface water in the
Vee than could run out through the skimmer. Con-
sequently, turbulence developed along the curve at
the sides of the funnel. If oil had been present,
there would have been substantial loss under the
boom. Even some of the ice cakes were carried under
the boom by the induced currents.
b. By positioning the tow boats at an interval of 100'
the surface water collected in the Vee was reduced
so that very little loss of oil would have occurred.
See Exhibit 24 .
c. It was evident that the same area could be swept
using shorter lengths of boom, and this would also
reduce the tendency of the booms to curve and
develop turbulence.
d. Many of the ice cakes caught inside the booms were
diverted into the entrance of the skimmer and
actually pumped into the sump of the skimmer.
e. Rough water tests were planned using the same
equipment layout and with shorter booms, but before
the rough weather arrived, Project personnel were
diverted to the Louisiana spill as reported in the
Appendix on that incident.
Diversion Boom Test
The final oil spill test in the project was conducted on
April 16, 1970. The objectives were:
a. To demonstrate a Diversion Boom technique in open
water, using a single boom placed at an angle
across the normal path of an oil slick, and thereby
to divert the oil to a skimmer, and
b. To demonstrate pumping action of the skimmer.
Equipment was positioned as shown on Exhibit 8 . Wind
from the Northeast was steady at 6 Knots, and was controlling
the movement of surface objects. Current was negligible.
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Oil was spilled at the up-wind end of the boom as shown on
the Exhibit. The boom was anchored at that end and
fastened to the skimmer at the down-wind end.
In 4 minutes the spilled oil travelled the 50' length of
boom and floated into the sluiceway leading to the skimmer.
At that point the skimmer pump was operated and all the oil
in the spill moved into the skimmer sump ready for pumping
into a floating tank, separation and disposal.
The boom had been deployed carefully so that it did not
cross the normal path of the oil flow at more than 20
degrees. (The greater the angle of boom to oil path, the
more tendency for turbulence to develop and to lose oil
under the boom. 20 seems to be about the maximum angle
permissible under conditions described.) The boom was
fastened to the skimmer with the telescoping fastening
device which has been used successfully throughout our
project.
As a result, all the oil was contained, diverted to the
skimmer, removed from the water and delivered to the skimmer
removed from the water and delivered to the skimmer sump '
without leakage at any point in the process.
The Diversion Boom principle performed as desired under
these test conditions, because all elements of the system
performed their tasks effectively and contributed to the
necessary end result - that of removing the spilled oil
from the ocean and delivering it to the oil disposal
system.
It seems evident that this Diversion Boom technique can
be developed to the point that it will be effective even
in rough water conditions.
Modifications of Commercial Equipment
Testing of commercial equipment loaned to this project by
suppliers gave evidence of many opportunities to improve
various features of the equipment.
Careful records were kept whenever opportunities for such
improvement became apparent, and detailed reports were
sent to nine of the suppliers listing favorable and un-
favorable items and making suggestions for modification
whenever possible.
At least four of the suppliers have advised that they modi-
fied their equipment to overcome the problems which became
apparent from the testing program of this project.
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Copies of correspondence with the suppliers have been
assembled into a single volume which has been sent to
the project Contract Officer for in-house circulation,
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Appendix B
THE LOUISIANA SPILL February/March 1970
Introductions; Disaster and Opportunity
On February 11, 1970, fire broke out in the engine room of
"C" Structure, an offshore oil well platform belonging to
the Chevron Oil Company and located about 70 miles south-
east of New Orleans and 14 miles east of the town of Venice,
Louisiana, on the Delta of the Mississippi River.
The fire was one of the worst in oil well history. It
consumed all burnables on the structure and destroyed all
production equipment on the platform. 22 oil well casings
emerged from the ocean bottom at that point and had been
controlled at "C" platform. At the time of the fire about
half of the 22 wells were producing oil, gas or a mixture
of the two. The other wells in the structure were not
productive.
The oil and gas emerging from the damaged casings fed the
fire and the resulting flames formed a roaring torch as
high as 200' above the surrounding waters.
Oil well fires are not unknown and the technique for
extinguishing them has been successful for many years.
The Chevron Division which operated the oil well lost no
time in calling the Red Adair Company of Houston, Texas,
to plan for extinguishing the fire, and operations for
that purpose got under way.
The worse aspect of the fire was the potential for a
disastrous oil spill. "C" Structure had been producing
nearly 2000 barrels of oil per day prior to the fire. As
long as the fire burned fiercely it was expected that most
of the oil emerging from the damaged well casings would be
consumed by the flames and oil pollution in the surrounding
waters would be minimal, and this proved to be the case.
As soon as the fires were extinguished, however, any oil
gushing from the damaged wells would fall into the ocean
and a massive oil spill situation would develop. This also
proved to be true.
The Company sought help from many sources both within and
outside of the petroleum industry. Surprisingly enough,
the Company had heard of the testing project in Portland
Harbor and on February 12th a telephone call to Portland
asked for project personnel to go to New Orleans to give
advice and assistance on plans for minimizing the oil
pollution and for cleaning up the spill which was expected.
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At that time, the project was in its final month of testing.
A leave of absence from the project was immediately obtained
from the FWQA and the senior consultant on the project flew
to New Orleans for a conference on February 14th. He
stayed on the job for 5 weeks.
It is not often that a research project has an opportunity
to test its findings so quickly and on such a large scale.
Lessons learned on the testing project were made available
to Chevron and to all the other personnel who were assembled
to work on the problem. Techniques developed on the project
were useful in deploying oil spill booms, controlling the
flow of oil after the fire was extinguished, guiding the
flowing oil to areas where skimmers could remove the oil
from the water, separating the oil from the water and
delivering the recovered oil to a refinery where it became
useful product. Something over 30,000 barrels of oil was
skimmed from the ocean surrounding the "C" Structure,
perhaps as much as 36,000 barrels.
This was the largest recovery of oil from the oceans surface
in all the recorded history of oil spills. The volume
recovered was probably 85% of the total spilled, and the
recovery of such a volume took the muscle out of the spill
and was a major factor in preventing the oil from reaching
the mainland.
The following paragraphs of this Appendix report the high-
lights of the planning, equipment procurement, training and
operation of the clean-up program as observed by the
consultant from the testing project who worked on the Louisiana
Spill for the Chevron Division.
Analysis of the Situation February 14, 1970.
As of February 12, Chevron had very little oil spill equip-
ment on hand in Louisiana. 1000' of curtain boom had been
obtained locally and 1400' of 36" light fence type boom
had been ordered. The consultant suggested placing orders
immediately for additional light fence type boom and
advised Chevron where it could be obtained.
Supporting equipment was available in considerable volume
at the oil field base in Venice, Louisiana and in the New
Orleans area. Work boats, crew boats, amphibious planes,
helicopters, and a very efficient microwave telephone
network plus land lines (to "H" Structure 2 miles from the
fire) provided transportation and communications.
As of February 14, additional equipment began to pour in
to the Venice base. Marine equipment included anchors,
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lines, marine hardware, buoys, floats and all the support
equipment used in oil field work.
Steel plates, tubes, pipes, casings, auxiliary pumps, and
engines arrived by the truckload. Portable welding and
cutting equipment was ordered to supplement the inventory
usually maintained at the Venice base. The staging area
at Venice rapidly came to resemble a military base for an
amphibious assault force.
At the first full scale conference at Chevron Divisional
headquarters on February 14, basic assignments were made.
Responsibilities were delegated to several task forces to
work on fire fighting in cooperation with the Adair Company,
a "Pollution Team" was assembled to develop a plan for
combating the oil spill, specific duties and responsibilities
for procurement, land transport, water transport, air trans-
port, housing and communications were determined.
At that time, it was announced that the pre-fire production
rate on "C" Structure had been 1800 barrels of oil per
day. That volume had been flowing from a group of 12 well
casings on the platform, and the other 10 wells had become
unproductive and were considered plugged.
The Pollution Team was made responsible for estimating the
volume of oil flow which could be expected after the fire
could be put out, and to plan the equipment program, crew
selection and training and the operating plan for cleaning
up the expected oil spill. The consultant from the Portland
Harbor Testing Project was assigned to the Pollution Team,
working with 5 Chevron engineers and assisted by field
representatives of equipment supply houses, research and
engineering personnel from standard Oil of Southern
California (parent company of Chevron) and of the Shell
Oil Research Laboratory at Houstin, Texas.
Weather situations could be very important, and a local
meteorological service was employed to brief the group
on prevailing weather patterns and to supply up-dated
forecasts around the clock every four hours. This service
was continued throughout the program and proved to be of
great value in planning day to day operations.
Briefing indicated that on a year-round basis prevailing
winds would be from the Southeast. This was the worst
possible direction as such winds would tend to drive
spilled oil from the "C" Structure directly toward the
oyster beds and wild-life refuges which were abundant on
the Eastern side of the Delta and Southeast of New Orleans.
However, at that season of the year the prevailing pattern
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could be expected to include cyclonic storms travelling
across the Gulf of Mexico, and resulting wind patterns
would probably go around the compass every two or three
days. This prediction was generally accurate. Four
storms of severe intensity were experienced during the
next five weeks.
On Sunday, February 15, the Pollution Team made an aerial
reconaissance of the oil field and the burning structure.
As predicted, most of the gushing oil was being consumed
by the fire and no large slick was apparent in the area.
Later it was learned that partially consumed blobs of
oil were falling into the ocean in some quantity, but most
of the light ends of oil had been burned out of them, and
they did not spread into a continuous film of oil.
The Pollution Team was quartered initially at the Venice
base and addressed itself to the planning of clean-up
operations which would have to start on a full scale as
soon as the fire could be extinguished. That date was
expected to be about March 5.
The Equipment Build-up - Skimmers
Upon arrival at Venice it was found that Chevron had pro-
vided two 130' work boats, each equipped with two 40'
r-pray outriggers, inductors and a deckload of detergents
for disposal operations. Plans for the spraying operation
were abandonned, however, in view of the decision by FWQA
that such spraying would be extremely harmful to the ecology,
Mechanical removal of the oil spill became mandatory, and
it was immediately evident that there was no supply of
skimming equipment anywhere in the country to meet the
requirements of the expected spill.
Experience with circular weir skimmers on the testing
project had been encouraging and a crude copy was designed
which could be built by local welding shops.
The first such skimmer was built in 24 hours by a welding
crew which worked around the clock. The skimmer was fitted
with a 4" discharge nozzle and was coupled to a 4" impeller
pump driven by a diesel motor. Initial testing on February
17 showed that the skimmer had a through-put capacity of
440 gallons of liquid per minute. (See Exhibit 12 .)
At that time, best estimates were that a total skimming
capacity of 75,000 barrels of liquid per day would be
needed to handle the flow of oil after the fire. That
figure was based on a maximum expected oil flow of 7500
barrels of oil per day (42 gallons per barrel) and an
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expected skimmer efficiency of 10% (10% oil and 90% water.)
The first skimmer, having a through-put capacity of 440
gallons per minute, would handle 600 barrels of liquid
per hour or 14,400 barrels per 24 hour day. Six such
skimmers would provide a through-put of over 80,000
barrels per day if each could be used at full capacity.
Sea tests were first conducted on February 21 from the
work boat Van Tide. Waves were 8* high with some breaking
crests driven by a 40K wind. The skimmer was buoyant and
rode the waves well, the intake platform staying normal
to the slope of the waves to a surprising degree. It
was adjusted to skim a 3" deep cut and the input kept the
4" pump operating to capacity at all times. Inflow of
surface liquid for a distance of 8' to 10' was apparent.
The Company built 20 of these skimmers (called the AK
design) and later built 12 of a slightly modified design,
lighter in weight and adjustable for skimming in thin oil
slicks.
They were eventually deployed on skim boats (See Exhibit
13 .) and on barges. They were heavy and crude and
required power lift equipment to move them on or off the
boats, but they performed reasonably well.
Booms
By February 20, a good supply of booms had been accumulated
on the site. Field representatives of the boom suppliers
were active in preparing these booms for use and training
personnel in assembly and launching techniques.
The problem of using the booms to best advantage was a
subject of much discussion. Experience on the Testing
Project indicated that booms would not be effective as
a fixed barrier across the path of an oil spill, but that
they could be used as trawls to collect pools of oil in
which skimmers could operate effectively.
At this point, the Pollution Team commandeered one of the
work boats which had been equipped with spray outriggers.
A demonstration was arranged on February 22 using a light
fence boom towed in a loop behind a spray outrigger.
Waves were about 4» high and the boom rode the surface
quite effectively. The work boat "3M2" towed such a boom
for several hours in an area where the oil blobs were
falling into the water from the burning well. Wherever
such blobs were in abundant supply, it was possible to
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collect a pool of oil which almost filled the loop of the
boom. Maneuverability was good, as had been expected,
although the boat had to run its engines at dead slow
speed to keep its speed relative to the surface at 1^ K
or less.
Skimmer Boats
The demonstration of boom handling plus the success of the
skimmer tests offered the beginnings of a complete system.
Chevron engineers suggested the use of skid-mounted tanks
on the deck of the work boat for primary separation of
oil and water mix and the result was the skimmer boat
design shown on Exhibit 13 .
Within the next ten days 6 boats were equipped as shown in
the exhibit and crews were trained to operate them on a
2-shift basis. Each boat carried two outriggers, two
floating booms of the light fence type, two 4" pumps with
diesel engine drives and one or two skid-mounted tanks
of 210 barrel capacity for separating operations.
Additional equipment included portable welding equipment
and oxy-acetylene burning sets. A welder was stationed on
each boat and 4 mechanics were on call on nearby crew boats
to handle pump and engine problems.
Later in the project these skimming boats demonstrated a
capacity to collect upwards of 500 barrels of oil per
boat, per day, working about 18 hours of each day. The
water content of the oil was 10% or less, due to the use
of the skid mounted tanks as gravity separators. Content
of the tanks was emptied into tanker barges for transport
to a shore based refinery.
Skimmer Barge
While the skimmer boat development was going forward,
Chevron engineers mounted additional skimming equipment
on a steel barge. Two Vee-shaped weldment structures
served to concentrate the surface slick at two points
on one side of the barge. At each point of the Vee an
8" suction nozzle and a 4" suction nozzle mounted 4" below
the surface combined to give the barge a pick-up capacity
in excess of 1000 barrels per day of oil. Two 1000 barrel
tanks were mounted on the barge. The barge was maneuvered
through the oil slick by two tugs, one at each end. When-
ever it could be positioned in a portion of the slick where
the oil was thick it proved to be the largest producing
unit in the fleet. Mercury vapor lights mounted on the
deck of the barge provided good illumination of the surrounding
water so that the
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operation could continue effectively after dark.
The suction nozzles were not equipped with any skimming
device to separate the oil from the water at the point
of recovery. The design was predicated on the principle
which had been adopted in Portland; namely, get the oil
out of the water as fast as possible and take as much
water with the oil as is necessary to do a complete job.
Then separate the oil from the water later in the system.
Both the skimmer boats and the skimmer barge worked on
that principle and worked successfully.
The Barrier Barges
While the skimming fleet was under construction, the Company
moored a string of 8 dead barges Northwest of the fire at
a distance of about 1000 yards. Each barge was 300' long.
Gaps of 100' between barges were closed with floating booms.
The intent was to provide a barrier between the source of
the expected oil spill and the most sensitive shoreline to
the Northwest. This is the path wherein prevailing winds
would probably generate the most dangerous threat to the
mainland.
Experience in the Portland testing program had shown that
such a barrier would not contain any great amount of oil
for any length of time under prevailing conditions of wind
and current, so skimmers and pumps were mounted along the
sides of the barges toward the burning well.
The results of this effort were mixed. On four separate
occasions storms drove the barges out of position, breaking
the connecting booms away from the barges and destroying
large sections of the booms. Different styles of booms
were tried. One heavy fence type boom, manufactured almost
on the site on a special barge, proved to be stable under
storm conditions as long as its mooring lines remained
intact. Other heavy and light fence booms foundered on
the barge anchor cables and were only intermittently effective,
All in all, the experience reinforced the conclusions reached
at Portland that booms have only limited value when used as
a barrier across the path of an oil spill.
On the plus side, the barrier barges did function well as
a diversion boom on those days when the oil spill approached
the barrier from a slight angle. The oil slick ran along
the windward side of the booms for a distance of several
hundred feet until it came to the end of the string. During
brief periods, skimmers were operated effectively from the
decks of barges and the oil/water mix was pumped directly
into settling barges moored alongside the barrier.
Furthermore, the barrier provided a most welcome breakwater
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effect on several windy days and the skim boats were able
to operate much more effectively and comfortably in the
protected area behind the barge line.
Fire OutOil In
The fire was extinguished briefly on Sunday, March 8, but
red-hot steel in the vicinity of the well tops re-ignited
the gas and oil mixture after about 12 minutes. During
that 12 minute period a substantial pool of crude oil fell
into the ocean and started to move toward the Southwest,
urged along by a 4K current. Sea and wind were calm.
The skimmer fleet was in position about 2 miles down stream
of the "C" Structure. For safety reasons (because of a
possible explosion of oil laden air if the well re-ignited)
the skimmer boats were kept at this distance. By the time
the oil reached the boats it had split up into a number
of small rivulets. Consequently the skimmer boats had to
pick up small pools wherever they could be found and the
boats could not skim steadily in the thick pool of oil near
the spill.
When re-ignition took place, there was no flash or explosion
of any sort. The fire started as a small flame, then gradually
spread until all the emerging oil and gas was burning at the
same volume as before.
However, enough oil had been spilled during the 12 minute
period to give the skimmer boats some good practice and
to demonstrate that they would be able to work effectively.
On March 9, the second attempt to extinguish the fire was
successful, and no further re-ignition occurred. On that
day, the wind had changed and was blowing toward the North-
west. The skimmer boats were positioned about half a
mile from the "C" Structure because the danger was felt to
be minimal. They got into effective action much more
quickly, and worked until dark.
The spill continued through the night, of course, and next
day's dawn patrol by helicopter showed that some slicks
were 5 to 7 miles away from the area. Two skim boats were
dispatched to clean up those remote streamers of oil while
the other boats moved in as close to the spill as possible.
Unfortunately there was so much equipment moored close to
the "C" Structure to support the fire fighting effort that
skimmers were seldom able to get closer than 1000'.
The oil stream floating down current from the "C" Structure
was 50' to 80' wide for about \ of a mile. Then it began
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to break up into multiple streams, the slick became thinner
and skimming efficiency was reduced. This experience con-
firmed another principle developed at the Portland project;
namely, skim as close to the source of the spill as
possible where the oil is thick and concentrated and where
the skimmers can be most effective.
Effect of Wind and Current
At this point it became apparent that the clean-up operation
had to deal with two spill patterns, one responsive to
tidal currents in the area and the other responsive to
winds. A fine, oily mist floated on the wind for two or
three miles from the "C" Structure, finally dropping into
the water and becoming responsive to surface currents
thereafter. This mist was coming from the one oil well
which was "gushing" after the fire was put out.
Three or four other wells were emitting oil at very low
velocities, and this oil dropped immediately into the ocean
at the foot of the structure and was immediately swept away
by the currents which reached a speed of 4K at many times.
This existence of two spill patterns, (Exhibit 25 .) often
separated by a mile or more, required the dispatching of
two or more skimmer boats to deal with the airborn spill.
Skimming of the airborn spill was not efficient because
the spill was so thin and widespread by the time it landed
in the water.
Final Clean-up
As soon as the fire was out, the Adair Company personnel
moved onto the remains of the "C" Structure and capped
the wells which were still producing gas or oil. This
process took the better part of three weeks during which
time the skimming operation kept going at an increasing
pace.
Equipment was tested during this period, crews increased
their efficiency, mercury vapor lights were added to the
skim boats so that they could work effectively at night,
and the daily production of the skimming effort built up
steadily. On March 13 the skimmers delivered 1714 barrels
of oil (10% water or less) to the tanker barges for trans-
port to the refinery at Pass Romere. On March 14 the score
was 2367 barrels and on March 15 it was 3212 barrels.
Storms interrupted the operations on at least three
occasions after the fire was stopped, but the skimmer
crews developed ability to operate in rough water to a
surprising degree.
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The last day the Portland consultant was on the scene, skim
boats were operating in breaking swells 10» high driven by
a 40K wind. Captains had been given permission to run
for sheltered waters at Lonesome Bayou, but elected to
continue skimming. It was found that by hoisting their
windward boom out of the water and skimming only with the
leeward boom on the sheltered side of the boat, the operation
could be continued effectively although at a reduced pro-
duction rate.
By the time the last oil well had been capped several days
later, the situation had been saved. No oil had reached
the mainland. No oil had reached into the oyster beds.
One small slick did reach an uninhabited island in the
Chandeleur group. This was a game refuge and the Company
had 40 men, 1000 bales of straw, a helicopter and work
boats on the scene to clean that spot in a few hours.
Meanwhile, protective booms had been placed at many points
along other shore lines which might have been threatened,
but those resources were not used.
Obviously, there were some very favorable circumstances
to assist the clean-up effort. Most important was the
time interval of three weeks before the fire was extinguished,
That gave opportunity to assemble equipment and personnel,
train crews and plan an organized effort.
The wind was a factor both for and against the effort. If
the wind had been calm, skimming would have been relatively
easy. Storms tore up the barrier barges, handicapped the
boat operation and rocked the boat in more ways than one.
The fact that the wind changed so frequently was a big
help because unfavorable winds did not persist for more
than three or four days at a time.
One cannot avoid the conclusion, however, that with the
continued development of equipment and with stockpiles
of equipment and trained personnel at strategic locations
around the shoreline, massive oil spills can be cleaned
up if they do occur.
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Appendix C
"OIL SPILL IN BOUNDING BAY"
(A Narrative)
This section is written for the man who has to work on the
clean-up of an oil spill. He may be a workboat captain
or a deck hand, an equipment dealer or maintenance man, a
marine repair expert, a salvage master, a city fireman
or a Coast Guardsman.
Whatever his job on the team that is gathered together to
fight an oil spill, this section of the report is an attempt
to pass along some practical information from other men who
have faced the same problems.
Many people have worked on oil spills. They have learned
a great deal about oil slicks and the kinds of equipment
which can be used to clean up the mess. They have tried
new equipment and seen it work in some cases and fail
miserably in others.
Some of the things they have learned are described here in
the hope that it will help everyone to do a better job
faster and more effectively when he is faced with the dirty,
tiresome and sometimes dangerous job of cleaning up an oil
spill.
Fortunately, our knowledge of methods for cleaning up oil
spills is growing rapidly, but we have a long way to go and
there are no easy answers.
Nevertheless, there are some things we can agree upon as
follows:
1. No two oil spills are exactly alike.
2. There is no one piece of equipment nor one single
method of attack which will work effectively on all
oil spills.
3. The attack on the oil spill must be planned in accordance
with the special characteristics of that spill, the
abilities of the people and the types of material and
equipment which are available.
4. Time is your most important ally. Don't waste it.
5. The principle of "skimming first and separating after-
wards" has been proved to be effective.
6. Recovered oil can sometimes be delivered to a refinery
and reconstituted so that its value is not lost. It
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need not be wasted, poured on the ground or burned to
pollute the atmosphere.
7. The clean-up job is not finished until the oil has been
removed so thoroughly that it can do no further harm
to property or people or the environment in which we
live.
We have a long way to go before we can feel secure in our
ability to clean up oil spills. However, at this writing,
good equipment is available at some locations to attack
some portions of the problem. A lot of Research and
Development work is being pushed forward by equipment
suppliers. New equipment is coming on the market at an
increasing rate. It can safely be predicted that workable
solutions of today's problems will be found with increasing
rapidity as this research effort goes forward.
The oil spill in Louisiana was cleaned up before any damage
was apparent. Unfortunately, very little oil control
equipment was available near New Orleans or anywhere
else in the United States, for that matter. Consequently,
it took three weeks to assemble necessary equipment and to
train crews.
Hundreds of men, scores of boats and airplanes, and many
thousands of man hours were involved, but more than 30,000
barrels of oil were removed from the ocean. That took the
muscle out of the spill, the oil that escaped the clean-up
effort dispersed or was blown out to sea as a very thin
"iridescent" film and eventually disappeared. The potential
disaster had been averted, and oil spill clean-up technology
had taken a long step forward.
The following pages of this Section provide, in narrative
form, a series of "how-to-do-it" suggestions based on
actual experience in two different types of oil spill.
Assume that you are in charge of oil spill clean-up for a
Township on the Maine Coast. You have a contingency plan,
an organization of men to work with you, a communications
network and an inventory of boats and oil spill equipment.
You have actually run a few training exercises, so you are
better prepared than most towns to take care of an oil spill
if one takes place. You hope it never happens.
7:30 a.m. The phone rings in your office on the Marine
Supply Wharf. The captain of a local work boat reports an
oil spill "out in the Bay". Try to get all of the following
information on the first call and it would help if you
had a reminder sheet close at hand which lists all the
important questions:
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Who is calling and where can you call him back if needed?
Where is the spill? (Locate it in relation to known reference
points in the area, or to a marine chart)
How big does it look? (Did the caller have a chance to
travel around it or did he come through it)
Is it spread widely over an area or is it a long narrow
stream of oil?
What color? Does it look thick or thin?
Any apparent indication of the source of the spill? Is
there a vessel involved that might be leaking oil?
What are the surface conditions in the area? Rough or
smooth? Whitecaps? How much wind? From what direction?
Rain or fog in the area? Does the oil spill seem to be
moving in any direction? Downwind? Or across the wind?
Any strong currents in the area? Are they tidal currents
or rive flow currents?
From the above information you can estimate the problem
and pass the information along to someone else who will
take over the shoreside duties, notify the Coast Guard,
answer the phone and talk to reporters. You have to go
out and clean up the mess.
From the information received, you estimate that some
passing vessel pumped its bilges and spilled about four
barrels of oil sludge into the usually clean waters of
Bounding Bay. The oil is reported to be black, which means
that it hasn't spread too widely, and maybe covers about
2 or 3 acres of the surface. The area is generally calm
without many strong currents, but the wind is blowing
steadily from the South at 9 knots and will probably move
the slick North toward Picnic Beach about four miles away
and the tourist season is just starting.
See illustration showing the situation on the following
page.
The spill will spread slowly, and the wind will cause it
to change its shape from a circle to a long-tailed slick.
The oil will move at a speed of about 3% of the wind
velocity, or about 3/10 of a knot. In about 12 hours it
will reach the Picnic Beach area. (Exhibit 26.)
At this point, your actions depend on the type of equip-
ment available to remove the oil from the water. You
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The situation looks like this:
PICNIC BEACH
SHORE
SURFACE:
8" WAVES
NO CURRENT
WIND
8 Knots
OIL
SPILL
cannot spray with detergents because there are too many
lobster grounds and clam flats in the area and, anyway,
detergents are illegal until you get permission. Your best
bet is to skim the oil out of the water before it can do
any harm to anyone.
You have two skimmers on your work boat. One is a small
capacity model, which pumps 100 gallons per minute and is
suited to shallow, calm waters. The other is a heavy duty
model which can pump 400 gallons per minute. (You also
have 1000 of air barrier hose, an air supply boat, and
2000 of a light, fence type boom.
Get those skimmers into action as fast as you can and at a
point where they will do the most good. Use your other
equipment to make the job easy for the skimmers.
-100-
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You only have 4 barrels of oil (about 200 gallons) to pick
up, but you may have to pick up as much as 4,000 gallons
of oil/water mix in order to get all the oil out of the
water. So you need your big skimmer to attack the major
portion of the oil spill. Use the small skimmer to go
after small patches of oil which may become separated
from the rest of the slick.
What about protecting Picnic Beach? You have 12 hours
before that area is threatened, unless the wind gets
stronger. The wind always get stronger later in the day
so you send a crew to set up the protection of Picnic
Beach now while you have time to get it done.
Back to the slick.
Where do you place your big skimmer? You have two choices,
because you know that you have to take the skimmer to the
oil or else bring the oil to the skimmer. Now you have a
job for your oil containment booms.
Given the situation that is described, there are at least
two ways to deploy your oil booms depending on the probable
movements of the oil slick.
One plan is to contain the slick by putting a boom all
around it, or by collecting the oil inside a loop of the
boom. This means that you have to prevent any further
movement of the oil. The other plan is to divert the
flow of the oil to a point where you can skim it.
So you get out to the slick as fast as possible with your
manpower and equipment and take a look at the slick. You
find that the shape of the slick is now changing due to the
wind, and the slick is about like this:
SHORE
PICNIC BEACH
SHORE
SURFACE:
8" WAVES
NO CURRENT
WIND:
8 KNOTS
500
-101-
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The slick is 500' wide and 1500' long. You have only 2000'
of light, fence type boom. Not enough to go all around the
slick. But you know the wind will probably continue to
move the slick north. There are two ways to use the wind
to your advantage.
You might put 1000' of boom across the path of the slick
and hope the wind will push all the oil into the arc of the
boom. Then you could operate your big skimmer in the pool
of oil which collects in front (upwind) of the boom, as
shown in the next sketch.
TO TANKER
WIND
If you elect this pattern, keep in mind that you are
dependent on anchors to hold the boom in place, you have
to hold your pump boat and skimmer in place against the
push of the wind. You may have to keep a work boat inside
the boom in order to hold the skimmer in place. If the
wind changes you have a lot of moving to do.
A more flexible approach is to use your boom to divert the
oil to your skimmer as shown on the following page.
Here you can hold one end of your boom close alongside the
edge of the slick with an anchor or with a small boat. The
oil will collect along the wind side of the boom and then
will be diverted along that side of the boom to the skimmer.
The skimmer can be held in position by making it fast to
one side of your pump boat. As the slick arrives at the
skimmer, the oil/water mix is pumped into the separating
-102-
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(b)
SLICK
tank on the pump boat and the clean water from the bottom
of the tank can go back into the ocean ahead of the skimmer
so that any oil which goes overboard will be picked up
again by the skimmer.
To make this pattern work properly, be sure that you do
these things:
1. There must be an oil-tight connection between the end
of the boom and the entrance to the skimmers at (a),
and another oil-tight connection at (b) between the
skimmer and the pump boat.
2. Position of the up-wind end of the boom and of the work
boat must be changed quickly as the wind shifts. The
flow of the slick must continue into the area between
the boom and the pump boat.
3. The pump boat must have enough tank capacity to handle
the volume of oil/water mix coming from the skimmer. A
1,000 gallon tank would be minimum.
4. The skimmer must operate steadily, because there is not
much area for a pool to form between the pump boat and
the boom, and if this pool is allowed to overflow, oil
will be lost under the boom or around the boat.
5. If a floating fabric tank or other vessel is available
to receive the oil from the tank, that vessel should
be standing by and ready to operate. It might be
desirable to pump directly from the skimmer into the
floating tank or vessel and let the separation process
take place in that vessel or on shore.
-103-
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The angle between the wind direction and the boom
should not be greater than 20 . With more angle,
the boom will tend to develop a belly in its shape and
oil may be lost under the boom.
Be sure to have a good supply of gasoline or diesel
fuel on a work boat to supply pump motors.
Too much angle between wind and boom.
Oil will be lost here.
WIND
Now you have your diversion boom in position and the oil
is beginning to arrive at the skimmer and going into the
tank along with a lot of water. Maybe about 10 gallons of
water to a quart of oil. Don't worry about the ratio of oil
to water as long as your skimmer is taking the oil out of
the water as fast as the oil arrives at the skimmer. The
separating tank on the pump boat, or in the transport
vessel (tank or barge or oil boat) or on shore will take
care of that problem.
But if the oil starts to arrive at the skimmer faster than
the skimmer can take it out of the water, oil will soon
overflow around the pump boat or will pass under the boom
and skimmer.
Now you still have 1000* of oil boom to use. You can rig
another diversion pattern like the first and use the small
skimmer. Or, you can use a containment pattern to hold
the escaping oil.
The containment pattern might be better here, because your
oil will be leaking from the overflow of the first skimmer,
and it should be moving in a very narrow stream. Therefore
you don't have to collect the oil from a wide area as you
did with the first boom. You just need a big storage area
-104-
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to contain the leak until you get another skimmer into
operation. So your second boom might look like this:
OVERFLOW
Overflow from the first boom system should be easy to hold
with a short length of boom, perhaps only 200', because
there will be a smaller volume, and it is already concen-
trated into a narrow stream. Get your second skimmer
going in the smaller pool and hope that the combined
capacity of the two skimmers is taking care of all the
volume that your booms have captured.
Meanwhile, check back at the beach. Your crew at that
spot has no boom to work with because you took it all
out into Bounding Bay. But they might have use for a
boom if you goof or if the wind rises and blows some oil
past the booms feeding the skimmers.
So they get ready to provide moorings for a boom when it
becomes available. Extra work? Sure, but remember the
tourists will be here on the first warm, sunny day.
How do you place a boom to protect a beach? An inert barrier
across the flow is not enough, because
1. If there is a lot of oil, the oil will go under the
boom.
2. The oil might miss the boom by 50 feet and run around
the end.
3. The boom is only a surface barrier. The best way to
protect the beach is to get the oil out of the water
and that requires a skimmer same remedy as out in
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Bounding Bay. So you take these steps:
1. Choose an area near the beach where you can operate a
skimmer.
2. Plan to put a diversion boom in front of the beach and
outside the line of breakers to lead the oil toward
the skimming area.
3. Place boom anchors at the proper spots so they will
be ready for immediate use when you have some boom
to work with. And place mooring anchors to hold the
pump boat and skimmer in position when they become
available.
4. In placing the anchors, set them solidly into the
bottom, take care that each has plenty of ground
chain and scope, and that the end of the scope is
supported on a mooring buoy for easy pick-up when
needed. And remember that there is a 12 foot tide
in Bounding Bay and you don't want the pump boat
moored where it will go aground at low tide. (And
the moon will be full tonight and maybe you have a
dreen low tide to contend with.)
So your defenses at Picnic Beach may look like this:
Picnic Beach
Rocky
Shore
Rocky
Shore
600
1
'10' at
I low tide,
6
-106-
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But you only have 500» of boom available, and that is not
enough to protect 600' of beach, particularly when you
have to place the boom at an angle.
So you decide to use your air barrier to protect the end
of the beach which you cannot shelter with the boom.
The air barrier is easy to place because it rests on the
bottom. And don't worry if the bottom is irregular. If
you have 81 of water over the air hose, the boil on the
surface (the Z line) should form a solid line of effective
surface current to divert the oil toward the boom and
skimmer. The pattern would look like this:
Picnic Beach
Rocks
(a)
'Skimmer will
Ibe here.
I
I
6
The barge or boat with the air supply can be positioned
as at (a). The air hose (weighted) can be deployed along
the line (b), (c). At (c) the end of the hose, should be
anchored on the bottom and a buoy should be used to indi-
cate its position.
-107-
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When the hose is in position, start the air supply and be
sure the barrier pattern is properly formed and positioned.
Some holes in the air line may need to be cleaned before
the oil arrives. Do it now! When the barrier is working
properly, put it on standby basis. Reduce the air supply
to a minimum that will keep the holes from clogging. If
you are equipped to pump fresh water or filtered salt water
through the hose to keep the holes open, do so.
Now you are ready to put the barrier into operation as soon
as the oil arrives and the boom and skimmer are in position,
So now you have your beach protected, and most of the oil
is being picked up out in Bounding Bay. What can go wrong?
Plenty. And don't forget Murphy's law, which states: "If
anything can possibly go wrong, it will go wrong."
Here are some things to look out for:
1. When the first boom was positioned alongside the spill,
the water was 60' deep. The wind did get stronger and
put a lot of strain on the anchor rode. The rode,
being at a downward angle, pulled the first fifty feet
of the boom under water. The remedy was to put a
mooring buoy on the anchor rode about 50 feet from the
end of the boom. That tends to keep the pull hori-
zontal on the end of the boom and reduce the chances
of it's being pulled under. This is a side view of the
anchor rode with a buoy.
<=
Wind
2. The strong wind generated waves 2 feet high. Normally,
your fence boom would ride up and down on 2 feet waves
without letting any water go over the top of the boom,
but the strain on the boom tends to limit the flexibility
of the boom in bending up and down over the waves. The
fix for this problem is to put more buoyancy along the
sides of the boom. If you are using the type of fence
-108-
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boom which has clips where more floats can be attached,
it is a relatively easy job. If not, or if the wave
condition is causing continued spilling of oil, the
strain can be reduced by using an extra line like a
bowstring from one end of the boom to the other, with
short lines from the bowstring to the boom at 30'
intervals (more or less) to keep the boom in a pattern
that looks like this:
Boom
Buoy
If you placed the boom, when the tide was high, con-
siderable slack will develop in the anchor rode as
the tide goes lower, and this may let the boom drift
out of position* If you have room to put out a long
anchor rode, try suspending a small anchor or 20 pounds
of scrap iron on the anchor rode halfway between anchor
and surface buoy. This will tend to keep the anchor
rode taut. The same type of arrangement, in very heavy
waves or swells can serve as an effective shock absorber
to minimize sudden strains on the line and its fastenings.
Pump
Boat
Boom
.... Surface
Buoy
Shock
Absorber
Anchor
-109-
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(Actually, you know all about these tricks because you
have been lobstering for years, but some of the younger
fellows and a lot of the tourists don't even carry a
good anchor in their boat, much less know how to lower
it overboard so the rode doesn't get tangled, or how to
back down on it to set it firmly into the bottom.)
So your first spill is cleaned up (didn't even leak past
the first skimmer) and nobody got dirtied and your equipment
is all back in order and ready to go again if you ever need
it. You never did find out who spilled the dirty bilge oil
on Bounding Bay, but you took a sample to show the Coast
Guard just in case they can analyze it and have some evi-
dence.
Then two weeks later the phone rings again. Wakes you up
at 2:00 a.m. on a foggy night. Local boatman just in from
across the Bay. When he docked, he noticed a wide ring of
dirty black oil around his white-hulled lobster boat.
Guessed there must be some oil spilled out there somewhere,
and thought you'd better know about it, and who is going to
pay for cleaning up my boat, anyway?
The usual questions don't provide many answers. He didn't
see anything or notice the oil when he went through it.
What route did he take? Just South of Thrumcap Island.
Came right past the spar buoy that marks the end of the
ledge, he guesses (which means he was probably exactly
where he said) but didn't see anything.
Wind from the North, beginning to blow a bit, expected to
back toward North West by morning and clear out the fog.
Tide just starting to ebb with current toward the South.
Someone in your office remembers that the weekly oil boat
(the Magnolia from Garden City) from down East was due in
tonight. Call her office on the 'phone and find out that
she reported radar trouble two hours ago. Maybe she went
aground on Thrumcap Island. Finally the ship-to-shore
radiophone brings word that she did, she's keeled over to
one side so that oil is leaking from her deck tank and the
leak will continue until they get some mechanics aboard or
until they get pulled off into deep water.
You alert the Coast Guard, call your team and send a boat
out to explore. He reports an oil slick about six feet
wide close to the stranded vessel, flowing to the South
and beginning to break up into three or four separate
streamers a few hundred feet from the wreck.
Now that you are an expert (because you have been through
-110-
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one spill successfully) you know that you must get your
skimmers to work immediately. And the best place to work
is close to the source of the spill where the slick is
concentrated and as thick as it will ever be.
Now you are confronted with a continuing spill which will
keep flowing until the source is stopped off, and you have
no way of knowing how much quantity of oil will eventually
leak out.
The only remedy for this situation is to get as much
skimming capacity out there as you can so that you have
capacity to pick up more oil than is flowing.
You dispatch your two skimmers with enough boom equipment
to divert the oil stream to the skimmers and their pump
boats. The storage boat follows along to take the skimmed
oil to shore.
You want more equipment, so a call to Portland brings a
promise of more booms and more skimmers by early morning.
Also a crew to operate them and two more small tankers to
help carry the skimmed oil to shore.
By dawn you are in business, with your two skimmers working
fairly well, but able to get only half the flow of oil that
is coming from the Magnolia.
So the pattern of your first skimmer operation might look
like the sketch on the following page. This shows 2 skimmers
positioned alongside a 50 foot barge which serves as a pump
boat, and is big enough to support a 500 barrel tank for
primary separation.
Note that you don't have to anchor the upwind end of the
boom. Just make it fast to the stern of the Magnolia a
few feet from the point where the oil enters the water.
(Note: every pattern of boom and skimmer operations shown
in the previous sketches has been tested and proved in the
testing portion of this Project. They work. The idea of
putting 2 or more skimmers alongside one barge was tried
out in the Louisiana spill. If the side of the barge is
positioned properly with relation to the flow of the oil
stream, the barge itself serves as a diverting boom and
will permit the overflow from the first skimmer to pass
to the next skimmer. The use of skimmers in gangs seems
to be feasible. The skimmers will be most effective if
they are moored alongside the barge so that they can rise
and fall on the waves independently of the barge. This is
a subject for further testing.)
-Ill-
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Rocky Ledges
Diversion
Boom
Vessel
Magnolia
Wind
Two skimmers in
tandem pick up 1/2
the flow.
60* Barge
with 2
skimmers.
Balance escapes
down current.
Now you need to know how bad the situation is down wind.
How much oil has gotten away from the site of the spill
and where is it headed?
You need an airplane or a helicopter. Get a report from
the air observer and you can plan far better than on the
basis of sea level inspection.
Fortunately, you find that very little oil escaped, and
you can send two work boats to tow 500* length of boom
between them and contain most of it about two miles down
stream. You also send your beach patrol crew to plan for
protection of any area which the oil might hit later in the
day.
The two boats towing the boom can work in this kind of
pattern:
-112-
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A.. On the way to the spill
Lead Boat tows boom,
\This end of boom runs f.ree.
No. 2 boat follows alongside.
B. At the area where oil can be collected
No. 2 boat,
Current
500' of boom.
On arrival at the down stream end of the spill, the oil
will probably be in several streams instead of one, and
the streams may be widely separated.
The Lead boat starts up alongside one side of the pattern,
and the #2 boat picks up the free end of the boom and tows
it very slowly until the #2 boat is exactly abeam of the
Lead boat , maintaining relative position just as accurately
as possible. This takes a little practice, but it can be
done.
By this means, the boom is pulled slowly against the current,
and the oil will collect in the arc of the boom. Speeds of
more than iJj K relative to the surface of the water will
cause leakage under the boom. Just hope that an additional
skimmer can reach you soon enough to pick up the oil before
the pool in the boom overflows or underflows.
If the boats are working into a current of more than lij K,
you will actually be going backward in relation to the
bottom of the ocean. By so doing, you keep your relative
speed to the oil at iJj K or less, and you keep the oil in
the "boom.
-113-
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At this point the truck convoy arrives with more equipment.
More booms and skimmers. You place the new skimmers where
they will pick up the oil flowing past your own installations,
You dispatch another new skimmer to help the tow boats with
the boom down the bay.
Finally you have just about enough skimming capacity to
take care of the flow from the stranded vessel, but if the
tide goes much lower, she may keel over more and the leak
will be greater.
At this point, the first small tanker arrives from Portland.
If you can get her into position to pump out the oil cargo
from the leaking tank, you will clean up a lot of oil before
it even gets into the ocean.
Also, you find out that there is an empty hold on the
vessel. Try putting a skimmer into the water alongside
and letting it work where the oil first hits the ocean
and pump that oil right back aboard the vessel into
the empty hold. (And why didn't the Captain think of that?
He did, but he didn't have a skimmer aboard. Maybe all
tankers should carry some of their own oil clean-up equip-
ment on board at all times. Another area for careful
Research and Development.)
You also have help from a large skimmer boat that came in
from Portland. It has a 200 barrel tank on board for pri-
mary separating, and deploys two skimming booms and two
skimmers patterned after the skimmer boats used in the
Louisiana spill. This boat is useful for patrolling
various areas around Bounding Bay where small patches
of oil have escaped from the booms, and in the course of
the day, the skimmer boat cleans up every pocket of oil
which the airplane or helicopter could find for her.
Radio communication is indicated, but if it is not avail-
able between aircraft and skimmer boat, get some of the
local lobster boats or cruisers to patrol the area and
report via their ship-to-shore phones or on the working
channel.
So by the end of the day, Bounding Bay is cleaned up, the
leak on the Magnolia has been closed, and the Coast Guard
has floated her. Your equipment is being repaired and
cleaned ashore and made up for the next need. A lot of
things were done right.
1. First of all, the attack on the spill started as soon
as the location was even guessed. No waiting for dawn.
(Sleep in the winter, after the tourists have gone home.)
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2. The first skimmers on the scene went to work close to
the source of the spill where the oil was thick and
where the flow had not yet split into a lot of small
streamers over a wide area.
3. Next, the attack was launched on every point that could
be attacked:
a. Skimming close to the source
b. Skimming down stream
c. Skimming alongside the vessel
d. Skimming the random patches of oil which escaped
from the booms
e. Beach patrol was working at any probable point of
impact of oil on shore
f. The oil supply feeding the leak was removed
g. Additional help was requested as soon as it was
determined that the spill was a continuing spill.
There was no waiting to estimate how much would be
spilled, which is very difficult to calculate
accurately unless the leak is coming from an ori-
fice of known capacity.
Several things went wrong. (Nobody has repealed Murphy's
law yet.)
1. The tow boats working down the bay needed more boom.
Some of the spare boom from Portland was sent to them,
but it was a different make and the end hitch didn't
match the one on the Bounding Bay boom. The crew
manufactured a quick hitch out of the oak slats from
a lobster pot (and ate the lobsters when no one was
looking) but they lost nearly an hour in the process.
(The process of repairing the boom, not the eating.)
2. By 11:00 a.m. your best boom man had to go haul his
lobster traps. By the time you got a replacement, one
skimmer had been starved of oil for nearly an hour.
(Remember, the booms are necessary to help the skimmers
work effectively.) When the booms don't work, the
skimmers can't work. And no booms ever took any oil
out of the ocean. (Except that which sticks to them
and is so hard to clean off that more attention should
be given to the cleaning process. Maybe the man who
sold you the boom should be asked to demonstrate how
to clean it after the first spill!)
3. On the skimmer barge one of the pumps overheated and
froze up. Unfortunately the discharge from the smaller
skimmer had been manifolded into the discharge lines
from the large skimmer so that there would be only one
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pipe leading to the top of the separating tank. Back
pressure developed in the small line and the pump had
to be replaced. Each skimmer pump should have its own
discharge hose into the tank. The pump has enough to
do just to get the oil/water mix out of the ocean with-
out having to fight another pump.) And the pump operation
should have been thoroughly tested and proven long before
this. (Dern it, can't think of everything.)
4. Early in the day, lots of work boats and sight-seers
cruised back and forth ahead of the skimming booms and
broke the slick up into a lot of small patches. This
made the job harder for the two tow boats operating
the sweeping boom. Get the Coast Guard to police the
area and keep all non-essential craft out of the path
of the working equipment.
Now you have cleaned up two spills, and you have a well
trained crew, good equipment on hand and you know where you
can get help if you need it.
The phone doesn't ring again for a long time. Maybe never.
Maybe the science of transporting oil improves to the point
that spills don't occur. Meanwhile, you keep in training,
stay alert, learn to use the newer and better equipment
that becomes available and you keep Bounding Bay clean.
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Appendix D
COMMUNITY RESPONSE TO THE OIL SPILL PROBLEM
Formation and Operation of^the
Portland Harbor Pollution Abatement Committee
The Port of Portland in Maine is a major oil receiving
port on the East Coast of the United States and it has
the potential to become the largest mover of crude oil
in the country. In 1968 the Port handled over 23 million
tons of crude oil and more than 3 million tons of refined
petroleum products.
Portland Harbor adjoins world-famous Casco Bay, one of
the most beautiful boating areas in the world and a major
center for Maine's Tourist Industry.
A group of citizens, concerned about the potential hazard
from oil spills, organized the Portland Harbor Pollution
Abatement Committee in 1966. Working in close cooperation
with the Maine Port Authority, that Committee very quickly
established a reputation for accomplishment in the Prevention
and Clean-up of the "nuisance" oil spills which accompanied
the petroleum activity.
By 1968 the Committee's program had produced the following
results:
1. Establishment of a communication network to respond to
an oil spill immediately with manpower and equipment.
2. Publication of an "Information Booklet on Oil Spills"
outlining response and reporting procedures, key
personnel, location of equipment and rules and regu-
lations under which the committee functions. Two
thousand copies were printed and distributed in answer
to requests from all over the country and from oil
ports throughout the world. The booklet has been used
by other ports as a guide in organizing oil pollution
abatement programs.
3. Extensive testing procedures on methods to move a
"containment device" (boom) to the scene. Testing
resulted in the design of a catamaran to store the
boom when not in use and to play it out on the scene
of a spill promptly and effectively.
4. Established procedures to react to a "mystery spill".
This created the greatest problem to the committee,
when oil appeared on the water in volume, and it was
impossible to establish immediate responsibility.
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5. Creation of a Data Bank on "oil pollution and abate-
ment problems".
6. Construction of a helicopter pad on the waterfront
to insure a more effective communication network
to handle manpower maneuvers and to track oil spills
in case of a major disaster.
7. The writing of an Oil and Hazardous Materials Contin-
gency Plan for Prevention, Containment and Clean-up
for the State of Maine was completed in January of 1970.
Five hundred copies of the "Contingency Plan" were
published on January 15, 1970 and within two weeks,
demands completely exhausted the supply and a second
order of 300 copies was delivered on February 15, 1970.
The plan was written to assist the 115 coastal commun-
ities in Maine to prepare action in case of minor
spills or a major spill effecting their community. It
was known in advance, however, that others were inter-
ested in the State of Maine plan, and it has now become
a model for both State and local level groups who are
interested in developing their own programs. Those
who wish a copy may obtain it by writing to the Portland
Harbor Pollution Abatement Committee, 40 Commercial
Street, Portland, Maine 04111.
More details of the contingency plan appear later in
this Section.
8. The Portland Harbor Pollution Abatement Committee is
incorporated in the State of Maine.
As a result of the above program, Portland has established
a world-wide reputation as a "tough port" where anti-
pollution codes are strictly enforced. Tanker captains
everywhere are passing word that, "When you're in Portland,
be very careful about spills or you'll find yourself in
a lot of trouble".
The project which is the subject of this report came into
being partly because of the community support which could
be depended upon to help meet the objectives of the testing
program.
Community Reaction to the Testing Program
The project was activated in August of 1968 on the basis
of a Federal Grant of $64,350 and "In Kind" contributions
from the area of $36,500. The purpose of this project,
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as defined in the Contract is to "Test and evaluate oil
booms and diffused air curtain bubble barrier for oil
spillage containment and the design, construction and
evaluation of oil recovery devices to remove the contained
oil from the waters". Oil recovery includes the ultimate
disposal of reclaimed oil and of sludge residues.
This project has generated a great deal of interest and
active support among the residents of the 14 towns and
cities near Portland Harbor and Casco Bay. The list of
Acknowledgments in the report gives only an indication of
the aid and assistance which was forthcoming from the area.
When help was needed it was immediately available. When a
potential hurricane threatened the test basin area, a
nearby filling station supplied a wrecking truck to pull
expensive equipment to high ground. In February of 1970,
when a "Nor'easter" with 60 mile winds drove booms and
the articulated skimmer ashore on Fort Gorges Island in
Portland Harbor, a lobster boat Captain took his boat
into shoal waters so that project personnel could recover
the equipment before pounding waves broke it apart.
These instances, and many others of similar nature, lead
to the conclusion that the success of an oil spill clean-
up capability depends in large measure on the support
which the effort receives from members of the community
it serves.
Consequently, the balance of this Appendix outlines the
type of community effort which should be organized to
assist in the procurement of equipment and the training
of manpower to provide ancillary support for a prevention
and clean-up program.
Objectives of a Community Effort
In order to function effectively, a community, company or
organization must have an "orderly plan" that has as it's
main objective, a program to prevent oil spills. When
spills occur, as they may, then it is necessary to move
into the second phase of the "organized effort", with a
plan to contain, remove and dispose of the spilled oil.
As a proven example of an effective community effort, the
following paragraphs outline the make-up of the Portland
Harbor Pollution Abatement Committee, types of membership,
operating procedures, funding, public relations and its
communications network.
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Membership
In Portland, Maine, the Portland Harbor Pollution Abatement
Committee is a non-profit civic group comprised of the
following: Industry (oil terminal operators, handlers,
vessel owners, etc.), waterfront personnel (towboats,
pilots, agents, etc.), city officials (city council, fire
and police departments, public works, etc.), Chamber of
Commerce, State Agencies (Port Authority, fisheries,
environmental improvement, civil defense, etc.) and con-
cerned civic and business leaders. It is important to have
legal counsel on the committee. Portland has two categories
of membership:
1. Regular members comprise those who contributed the
original funds under which the committee is able to
function, to buy equipment and commit itself to its
objectives.
2. Associate Membership comprises that group who contri-
bute annual dues. ($5.00 a year in Portland)
3. Membership is open to the public. The Portland
Committee mails "notices of meeting" to over 200 people
who have expressed an interest in the affairs of the
committee. There are no paid employees, as each member
contributes his time and expertise.
Operating Procedures
1. Portland Harbor Pollution Abatement Committee has
adopted by-laws under which it operates (a copy of
which will be sent to any group so requesting). The
Portland Committee has filed its Charter within the
laws of the State of Maine, therefore, is incorporated
so that no member can be involved in any third party
responsibilities in carrying out the objectives of
the committee. Incorporation costs range from $300 to
$500.
2. Officers and Directors must be elected, and it is
suggested that the Chairman or President name a small
executive committee (6 members) to function between
meetings, and to make recommendations to the full
committee.
Funding
In Portland Harbor the operators of the local oil terminals
contributed the initial operating funds to the committee.
The first contribution totaled $20,000.
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Communications
An information booklet was published that has been most
helpful in carrying out the objectives of the committee.
(A copy of the Portland booklet as a guide is available
upon request)
It includes the following subjects:
Identity of the committee and its objectives
Table of contents
Listing of responsible parties to be called in the
event of spill (phone numbers - office and home)
Location of equipment
Rules and Regulations on use of equipment
Boundaries of responsibilities
Phone numbers and locations of oil terminals
Communication network (radio)
Names of committee officers who have responsibility and
chain of command
Equipment Policy
The committee owns some oil spill clean-up equipment
and sets the policies and terms of its use. The equipment
is handled by a local marine repair firm which has man-
power and facilities available at all times.
Authority to call the equipment into use is delegated to
Portland and South Portland Fire Chiefs, the Captain of
the Port and designated members of the committee.
The location and availability of all other clean-up equip-
ment and material is listed in the Contingency Plan for
Portland Harbor. Thus, all equipment in the area can be
marshalled readily in the event of need.
Organization of Community Support in the
Clean-Up of Oil Spills
No approach to the clean-up of a major oil spill can be
successful without proper attention to the assembling of
manpower through a cooperative community effort. (Or
through a company plan if the company is large enough to
man and finance such a plan.)
If it is to be a community effort the leadership can be
supplied by the local Port Authority, fire departments,
civil defense head, or an industrial leader.
Han power should include:
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City or Town Officials (Manager, Councilors, Selectmen)
Fire Chief - Police Chief
Representative from Water Quality Commission (State-Federal)
Civil Defense Head
Coast Guard
Ships Agents
Port Authority
Harbor Master
Oil Terminal Operators
Fishermen
Waterfront business interests (Pilot-Towboats, etc.)
Contractors
Organizations (Chamber of Commerce - Petroleum Industry
Audubon Society - Educational Institutions, etc.)
Conservationist
Civic Leaders
Following the formation of a cooperative group to direct
energies and expertise to the problem, it is essential
to establish responsibilities and chain of command for
effective action in case of a spill. Suggested organization
chart with responsibilities:
Chairman and Oil Spill Coordinator:
Conduct meetings
Oversee and Coordinate programs
Act as spokesman to News Media
Organize Public Relations
Plan for Data Collection
Set date for test exercises
Plan for Research new equipment on market
On Scene Commander (Fire Chief, Coast Guard, Captain of
the Port:
On scene action
Surveillance
Policing
Reporting
Equipment responsibility
Coordinate on scene Program
Write and up-date contingency plan for port
Communications Commander
Provide and up-date phone numbers of key personnel
to be called
Calling key personnel should spill require it
Inventory of communication equipment (radios-
walkie-talkies, etc.) availability, condition,
repair, personnel and spare parts
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Surveillance equipment available (Helicopter-fixed
wing planes)
Establish Chain of Command response
Up-date instruction booklet
Supply and Inventory Control Officer
Publish and up-date complete inventory of equipment
Proper storage and maintenance
Replenish stock
Research and Reporting Officer
Keeps accurate records of casualty..writes it up
and disseminates information to key personnel
Analysis performance, makes recommendation
Records conditions at time of spill
Provides "On Scene Commander" with weather con-
ditions, .ship traffic..manpower and equipment
problems etc. types-capacities-number of ships
visiting port
Training and Critique Commander
Arrange and coordinate plans for "test Exercises"
Provide charts and maps for location of key areas
Diagrams and plans of action
Write "problem and action" report
Provide "grid" map on location of oil terminals-
fixed equipment-mobile equipment, etc.
Inspection and Equipment Reporting
Make periodic check of terminals checking facilities,
equipment, communications, etc.
Reporting to committee
Communications Network
It is important to establish and maintain a complete
communication network. This is to include radios, walkie-
talkies, whistles, flags, bull horns and lights for morse-
code signals.
Telephone communications are essential. In case of major
catastrophe the communication network must call in outside
help. This can be done through a planned program by tele-
phone or radio communication.
Fiscal Responsibility for Oil Spill Clean-Up
A spill can take place at anytime. It is often easy to
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spot during the day by either ship or shore personnel.
After' dark strong odors on the site may give the first
notice that a spill has occurred. In any event it is of
utmost importance to the success of the "operation" to
report the spill immediately to the responsible people
to set the "clean up process" in motion.
This is an area that deserves and requires careful "advance"
thought because the entire program can bog down at this
point.
Because of the cost of cleaning up an oil spill, usually
the work boat or clean up company must be assured as to
who will pay the bill. It is therefore, important that
whenever there is a call for "clean-up action" someone
must be ready to accept financial responsibility.
If the spill is from a ship (with no direct oil terminal
responsibility...that is a chartered ship to the terminal),
the order for clean up should come from the Captain of the
ship, or the ship's agent.
Experience shows that ship's captains and agents have been
reluctant to accept financial responsibility for the spill.
When there is more than one ship in port engaged in trans-
ferring petroleum products the problem is compounded.
In Portland Harbor, the PHPAC accepted responsibility to
pay for ordering out the clean-up crew should there be
any delay in determining responsibility. With some funds
in their treasury the committee knowingly opened up what
could be a pandora's box of financial responsibility, but
took the action in an effort to protect the community and
environment for any hesitation in "reporting a spill",
and accepting responsibility.
Fortunately and with credit to the petroleum carrying
industry, hesitation in accepting responsibility and
reporting now seems to be more of the exception then the
rule. It must be recorded, however, that this has been
a problem in the past, and does still remain a potential
problem and communities must be alerted to it.
The problem has been recognized by the Congress, which is
presently moving to make some part of $35,000,000 avail-
able for clean-up of those spills where responsibility
remains undetermined. The State of Maine is proposing
a bond issue of $4,000,000 for similar purposes.
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Conclusions
A well organized community group, dedicated to the pre-
vention of oil spills always and to immediate and effective
clean-up of oil spills when they do occur, is the best
guarantee of continued progress in the controlling of oil
pollution on navigable waters.
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Appendix E
A CLEAN-UP SYSTEM FOR MAJOR OIL SPILLS
Discussion of Available Resources
At this writing it is evident that considerable progress
must be made in the development of technology and the
readying of equipment in order to minimize or prevent
damage from a major oil spill.
It is true that one major spill was handled in Louisiana
in March of 1970, but there were fortuitous circumstances
involved which have not been present in other spills.
Furthermore, the technology which was successful in skimming
crude oil in Louisiana would not have handled the congealed
Bunker C oil at Chedabucto Bay in Canada in February, 1970.
The time factor at Louisiana permitted the building of 32
high volume skimmers before the spill reached major pro-
portions. Today, that skimming equipment may still be
available in the Louisiana-Texas area, (it has indeed been
used on at least one other spill near Galveston) but major
logistical problems would have to be overcome to make that
equipment effective at any great distance.
A gradual build-up of equipment is noticeable in many
petroleum terminal areas and operational spills are being
handled more effectively every year, but there is no evi-
dence of any marshalling of massive equipment at strategic
locations except in Louisiana to guard against the dangers
of a major spill.
However, among Federal programs already under way, the
Coast Guard has reported successful testing of off-loading
equipment (pumps and floating storage tanks) to remove
cargo from tankers at the site of a spill. The Coast
Guard will have prime responsibility for manning stations
where this equipment will be stored.
A major task of this project is to outline a feasible
system to be used to combat major spills. The following
paragraphs of this section contain specific recommendations
for such a system. The recommendations include specifi-
cations for equipment and suggestions for its use, as well
as basic operating policies which must be observed.
Basic Operating Policy No. 1.
Removal of spilled oil (skimming) is the essence of the
entire system.
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There are two basic skimming techniques which have been
proved successful. The circular weir suction skimmer
removes an oil/water mix from the spill area. It is simple
to operate, relatively inexpensive, maintains some effective-
ness in very rough water and can be used in multiple units
to develop massive capacity. It is most effective on crude
oils and light weight oils.
The endless belt (or revolving disk) skimmer has been
reported effective in removing viscous oils (Bunker C) in
the Chedabucto Spill in Canada under winter conditions
which made the oil too sticky to flow through the orifices
and suction hoses of a weir skimmer.
Basic Operating Policy No. 2.
Successful clean-up operations require sufficient skimmer
capacity to handle the volume of oil spilled in the time
available.
A skimming operation must deal with two types of major
spill. There is the finite spill, wherein the source of
the spill can be shut off quickly and the volume of oil
spilled can be measured or predicted with reasonable
accuracy. There is also the continuing spill wherein the
flow of oil may go on indefinitely.
For example, when a tanker ruptures two cargo holds, it is
probable that the spill will not exceed the contents of
the two damaged holds. The volume of clean-up capacity.
required can then be determined, making due allowance for
the time available for such clean up before storms or
other conditions make operations difficult or impossible.
In a continuing spill such as Santa Barbara or Louisiana,
the rate of flow can be estimated, but the duration of that
flow may be unpredictable. In such case, skimmer capacity
having a clean-up rate greater than the rate of flow is a
definite requirement.
Basic Operating Policy No. 3.
A clean-up operation should attack a spill at every point
where clean-up or additional prevention can be effective.
In a continuing spill, skimmers should operate as close to
the source as possible in order to skim the oil where the
film is thick enough to make for easy skimming and where a
minimum of booming or compacting is required.
At the same time, other skimmers and containment or diversion
booms should be operating at points distant from the spill
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where the oil slick has spread over a wide area or has
separated into a series of ribbon-like slicks.
Furthermore, booms should be placed to protect sensitive
areas threatened by the approach of a slick and skimmer
operations should be placed and ready to operate at those
points when and if oil begins to accumulate.
Basic Operating Policy No. 4.
Time is of the essence. None of the clean-up operations
should be delayed because of legal wrangles over responsi-
bility for the spill.
It should be a function of government to provide the
necessary authorization for immediate clean-up to take
place while such clean-up can still be effective. (On a
small scale, operations of the P.H.P.A.C. have overcome
this problem by authorizing immediate action in emergencies
and providing for determination of responsibility and
settlement of claims at a later date. See Appendix D. )
Basic Operating Policy No. 5.
The basic equipment for clean-up (skimmer, boom and storage
capacity) should be readily available at all strategic
points where oil spills might occur.
The strategic points include oil terminals where oil is
on-loaded or off-loaded, tank farms and bulk stations
located near the ocean, lakes or rivers, and on board every
tanker carrying petroleum products.
As regards tankers, consider the case of the Torrey Canyon,
aground on the Scilley Isles with several holds broken
open. If she had been able to drop two high capacity
skimmers into the oil slick alongside those leaking holds,
she could have skimmed a lot of oil out of the ocean and
held it on board even in the ruptured tanks until additional
help arrived.
Obviously, as oil leaks out of a ruptured tank, storage
space is available at the top of the tank. An oil/water
mix skimmed from the slick alongside and pumped into the
tank would find temporary storage. The water in the oil/
water mix would tend to migrate to the bottom of the tank
and go out of the break before the oil would follow. Valu-
able time could be gained and every bit of oil recaptured
even temporarily would represent a net gain in the clean-up
of the whole spill.
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Skimmer Capacity
The capacity of the circular weir skimmer used in Louisiana
was limited only by the capacity of the pump connected to
it. Thus, a skimmer working with a 4" pump of 440 gpm
capacity had a through-put of 440 gallons per minute of
liquid*
Pumping in a deep pool of oil, the capacity to pump oil
would be 440 gpm. Pumping in a slick, the capacity to pump
liquid (an oil/water mix) would still be 440 gpm, but the
volume of oil would depend on the oil/water ratio in the
slick.
In some thick slicks, ratios of 60% oil to 40% water have
been noted. In slicks where the oil has spread into a
very thin film, ratios of 10% oil to 90% water are more
usual. Consequently, capacity of the circular weir type
of skimmer is best expressed in terms of through-put of
liquid.
A separating skimmer, such as the endless belt design or
the multiple disc design separates oil from the water at
point of removal, and very little water, if any, accompanies
the oil.
In this case, the theoretical capacity of the skimmer can
be expressed in terms of oil removed per time interval.
In practice, however, the theoretical capacity is only
reached when oil is present in sufficient volume to keep
the discs or belt loaded to their maximum at all times.
Operating in a very thin slick, this type of skimmer would
suffer from lack of oil and its actual output would be
substantially below theoretical capacity.
System Capacity
Ideally, the capacity of a clean-up system should be equal
to the total capacity of the skimmers involved.
All other equipment should have capacities equal to or
greater than that of the skimmers. Otherwise, the skimmers
cannot be used to their maximum capacity. Inasmuch as the
skimmers are the most essential equipment in the system,
they should never be compelled to operate at less than
optimum capacity. Pumps, transfer hoses, storage tanks,
separating systems and transport vessels must be made
available in sufficient volume to keep the skimmers going
at optimum capacity. Otherwise, the system will not deliver
its intended volume and the clean-up effort will suffer.
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The Ultimate Size of Skimmer
As tankers grow larger and pose the possibility of massive
spills, the supply industry tends to think in terms of
massive skimmers to counter the threat.
Beyond a point, however, size can become a liability because
such size may boost purchase price and operating cost to
the point that very few units would be built and availability
would be limited. Size may generate mechanical problems
during rough sea operations, highly trained crews may be
required (and stand-by costs for such crews are considerable)
and big equipment may not be operable in many bays, harbors,
estuaries and shallow water areas where massive spills might
penetrate.
The immediate alternative is to design skimmers so that
multiple units can be worked in gangs where large capacities
are needed, just as gang mowers are used on a golf course,
multiple combines are used to harvest wheat fields or dozens
of pumpers are used at major fires to provide the massive
through-put of water.
On the basis of present information, circular weir skimmers
and pumps having a through-put capacity of 800 to 1000 gpm
might provide an optimum compromise of all factors. Used
singly, they would be readily portable by truck, boat or
plane. In groups of 2 or 3, they would provide capacity
to handle most of the spills which have been recorded,
and several gangs could be used simultaneously if greater
capacity were needed.
Conclusions
1. The type of equipment described above has been proved to
be effective up to the limits specified.
2. Basic clean-up systems built around the equipment speci-
fied would constitute effective systems to the limit
of their capacities. (Equipment should include both
weir skimmers and belt or disc skimmers.)
3. Individual systems, as described, would provide effective
clean-up capacity, adequate for many locations where small
spills might occur.
4. High mobility of the individual systems would permit
quick concentration of multiple units to combat massive
spills.
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Recommendations
1. Pending the development of major advances in technology,
units as described should be placed at strategic locations
throughout the United States.
2. Action should be initiated to install such units (or the
essential elements thereof) on all tankers operating
on routes where land based equipment is not close at
hand.
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Appendix F
AERIAL PHOTOGRAPHY OF OIL SPILLS
The aerial photography of the controlled oil spills in the
inner harbor at Portland, Maine was performed by Singco
Division of Montvale Industries Corporation. One purpose
of this mission was to provide a photographic record of
field operations at the test site. A controlled oil spill
was contained and harvested with appropriate test equip-
ment. Another objective was the aerial photographic
determination of oil-slick phenomenology and the relation-
ship of th'i detection process to aircraft search and
tracking operations during accidental spills on ocean
waters.
The photographic emulsions for the aerial missions were
infrared film (black and white) and color film to be
exposed simultaneously. The use of dual or multi-spectral
bands in optical discrimination systems can be effective
when the signals from the separate channels are analyzed
jointly. Color film can record subtle changes in hue.
The fact may provide additional dimension of information
beyond the capability of ordinary panchromatic film. In
order to provide a basis for comparison, it was decided
to use high speed panchromatic film as the third test
emulsion. Further, advantages of near real-time process-
ing of black and white film has operational significance.
Infrared film (black and white) is sensitive out to 850
millimicrons into the near infrared region of the spectrum,
Ordinary panchromatic film cuts off near 650 millimicrons
in the visible red. The use of infrared film in the photo-
graphy of terrestrial or marine scenes is based on the
differences in reflectance of solar infrared radiation by
earth features. Such features at terrestrial temperatures
do not emit enough infrared radiation to be detectable by
infrared film at a wavelength of 800 millimicrons. Energy
emitted by them at earth temperatures falls at wavelengths
10 times as distant on the wavelength scale. Conversely,
a heated flatiron in a dark room would have to have a
temperature of several hundreds of deg C to be recorded on
infrared film.
Instrumentation
A Cessna Light aircraft was instrumented with equipment
to perform the aerial photographic mission. A camera
mount was designed and constructed for use off the port
side of the aircraft. Three cameras are mounted along
the same line-of-sight at an angle adjustable from about
-133-
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30 deg to 60 deg from the nadir. The Nikkorex Auto 35
camera system is used with a trio of Nikkor H,F:2, 48-mm
lenses and with a 85-mm telephoto conversion lens and a
35-mm wide-angle conversion lens. Exposure settings may
be either automatic or manual.
The camera system is flexible and convenient allowing
adjustments in field procedure and in the choice of film
emulsions.
Aerial Photographic Mission of October 9, 1969
At Inner Harbor. Portland, Maine
The spillage, containment, and clean-up of a 100 gallon
spill at the field site in the inner harbor at Portland,
Maine was recorded from the air.
Takeoff at Bedford: 1045 EDT
Return to Bedford: 1700 EDT
Weather: Clear skies, light surface winds from NW
veering to the E in the afternoon, calm seas,
visibility unrestricted.
Flight Procedure Over Site: Elliptical pattern at an
altitude of 800 ft. view angle of 45 deg; exposures were
made at an aircraft heading of 130 deg from North with the
sun at an azimuth of 90 deg from the aircraft nose ( to
starboard) increasing to 120 deg at the end of the photo
mission. Photographs were recorded during the period
from 1300 to 1507 EDT.
Kodak infrared film (IR 135) and Kodak Tri-X Pan film
were used to obtain the black and white photographs in
this mission. A No. 25 red filter was used with the
infrared film and a No. 15 yellow filter was used with
panchromatic film.
Figures 1 through 7 are selected photographs showing the
progress of the operations at the test site as recorded
on two black and white emulsions. Evaluation and des-
cription of the appropriate features of the photos are
presented under figure captions.
Application of Aerial Photography to the Detection
and Tracking of Controlled Spills
The aerial detection of oil spills on the high seas poses
a different problem when the location and the extent of
the spill is unconfirmed or unspecified. Operational
requirements of an aircraft search and scan mission will
be concerned with target detectibility, background and
-134-
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false alarm discrimination, resolution at the ocean
surface, optimum altitude of flight, scantechniques, and
photo interpretation. Determination of these factors can
only be arrived at by investigating oil spills of signifi-
cant amounts on the high seas under conditions approximating
those that would be realized in an operational mission.
From the results of the photographic mission under clear
skies over the harbor at Portland, Maine, some conclusions
can be made which are reasonably extrapolated in the
direction of the larger problem.
Visual detection of the thick black oil spills easily made
with the unaided eye by an observer aboard the aircraft
from an altitude of 1,000 ft. under fair weather illumination
conditions. The appreciable oil-to ocean contrast can be
recorded with panchromatic film (Kodak Tri-X Pan Film)
with a No. 15 yellow filter to reduce atmospheric haze.
The oil strongly absorbs the visible light and the turbidity
of the marine background reflects enough radiation to pro-
vide a brighter background. Overdevelopment of the film
during processing can accentuate the contrast. The use of
this panchromatic film is useful to record the main denser
portions of an oil spill.
Ocean waters are typically very dark on infrared film
(Kodak IR 135) because of the high absorbtion of the near
infrared by ocean waters. Thick oil spills are similarly
strongly absorbing so that their contrast with the marine
background is only marginally detectable. However, in
later stages when the oil film is of molecular thickness,
infrared film is capable of bringing out the detail of
the oil structure as it diffused and transported in the
water. Such structure may be invisible with other emulsions
as can be seen by comparing the IR and Tri-X photographs.
The brighter structure of the thin oil film is in all
probability associated with optical interference at the
interface. It is not clear at this time whether other
contaminants in the water (algae or other pollutants)
would present interfering signals, and there is some
evidence of this. Shape discrimination will be useful
in this respect. (Exhibit 27.)
Infrared film are generally of slower speed and care must
be taken to insure sufficient exposure in order to capture
reflectance differences on water surfaces as the light
levels of interest are of low magnitude. Since the
desired detail falls close to the limits of the emulsion,
overdevelopment during film processing is recommended.
Infrared film is used with a red filter (No. 25 or 89)
to eliminate the blue light to which this film is also
-135-
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sensitive. This film-filter combination is especially
useful in viewing through atmospheric haze. With both
films, photo evaluation or photo interpretation can be
more suitably done by viewing the positive transparencies
with transmitted illumination and an optical aid.
The effect on the foregoing of adverse conditions of
illumination has to be further investigated. The infrared
content of sunlight is deteriorated under cloudy skies and
the effect of atmospheric haze through long slant paths
will also be unfavorable.
Note: This is an unedited report as received from Singco
Corp. The Grantee on 150-80-DOZ is not responsible
for content or conclusions expressed therein.
-136-
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CORE SAMPLES OF AN OIL SPILL
Objective
Program
Procedure
to generate basic information on type of oil and
quantity spilled.
to develop a method of taking "core" samples at the
site of a spill
a. Prom surface craft
b. Prom aircraft
to develop preliminary testa of the core samples
to indicate type of oil, volume, thickness of spill.
Core samples can be taken at the site by using a
conventional 6 gallon pail equipped with a drain
valve at the lower end.
.1. The pail should be immersed so that top
is well below the lower edge of the oil
slick, and with the valve OPEN.
Pail is slowly raised so that rim of pail
cuts through oil slick and emerges above
surface. Water below oil slick inside
pail drains out of the open valve while
the pail is being raised.
Pail is raised clear of the surface and
valve can be closed while clear water is
still in bottom of pail below the oil
sample.
Pail with valve closed and a tight cover
in place can be transported to laboratory
for analysis. Analysis can be both
.quantitative and qualitative.
Note: On the Singco Proj'ect Test, this procedure was followed
and quantitative tests were made by chloroform extraction
procedures.
Exhibit 1,
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-------
FORCES ACTING ON AN OIL SPILL
Forces Affecting Position in the Water
(Assume Wind Zero and Current Zero)
Specific Gravity
Less than 1.
Sprea
Spread
Sectional View
as Oil Droplet
Surfaces.
Gravity
Spread
Sectional View after
Spread Effect takes
place.
Downhill
Flow
Plan View of Forces
at Surface.
Forces Affecting Travel Through the Water
Wind
Wind
Section of a Thick Spill.
Force exerted by sub-
surface current due to
river flow or tidal
action.
Section of a Thin Spill,
«*«_^
Maximum area exposed to
wind effect.
Exhibit 2..
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TYPICAL BOOM DESIGNS
(Vertical Sections Across Boom)
CURTAIN BOOM
Freeboard 3"-6"
Curtain Ballast.
Weights, Cable or Chain
Float. Foamed
Plastic or Air
-Flexible Curtain.
Canvas or Plastic
LIGHT FENCE BOOM
Freeboard 8"-12"
Buoyancy Material
Foamed or Molded
Plastic
Panel Ballast
Chain or Cable
36" Vertical panel
may be plastic,
reinforced fabric
or metal.
HEAVY FENCE BOOM
Freeboard 24"
Buoyancy Float.
Plastic, Drums or
Inflated Chamber.
Tension Cables
Panel may be rigid
or flexible. Wood,
plastic, fabric or metal,
Exhibit 3.
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STANDARD TOWING PROCEDURE
Tide Rip
Arrows
Show
Current Flow
Outside of Boom
Oil Pool
Best Area
For Skimmer
Area of Maximum
Turbulence
Exhibit
-140-
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CURRENT PATTERNS UNDER A FENCE BOOM
Boom towed in this direction*
Pi
Area of
Maximum
Turbulence 12"
Fence
Barrier
Pool Area
Tide Rip Area
oo^° o
Flow Arrows indicate Relative Current
past the fence barrier
-------
MOVING OIL INSIDE A BOOM
TO COMPACT THE CONTAINED OIL
Procedure used during Singco Project test of October 9,
1969.
1st Observation - 200' Offshore at start of Skimming pro-
cess .
Work
Boat
2nd Observation - Oil Slick coverage after 10 minutes of
skimming - result of wind
Oil
This pool of oil protected
from wind by 12" freeboard
of boom. A second skimmer
could have operated in this
area.
This pool pushed toward
skimmer by the wind.
JSrd Observation - Boom re-rigged by slacking mooring
lines #2 and #3 and shortening
line #1.
'Skimmer
Wind no longer blocked by
freeboard and could push
remaining oil pools to
position shown.
Skimmer was shifted to
down-wind corner and
clean-up completed in
another 40 minutes of
pumping in a very thin
film.
Boat-
Exhibit 6.
-142-
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TOWING A FUNNEL BOOM
Lead-Boat
#2 Boat
Bridge
Sluiceway
Bowstring
tension line
reduces sharp
bend in boom.
Turbulence and
loss of oil at this
aharp bend.
Exhibit 7,
-143-
-------
DIVERSION BOOM TEST
Anchor
Oil spilled
at this point
progressed along
\jj indicated path
jl to skimmer. No
/
leakage under
boom.
10K Wind at
20° to Boom
Anchor
Exhibit 8.
-144-
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CURRENT VELOCITIES NEAR AN AIR BARRIER
"Z" Line *-j 1.26K
Surface v
Boil \~ *
^. t?-*.r~f~^^ ~* ' ^*~^~r~^f~~>r^
^N>0\ !'//''
\ \\ 1 1 ^/A
iillfj/
' T
y .7K
8' Below Surface (>** M"^"*"
120 CFM 9 100 P.S.I. ^ A^rier
1.13K .82K .63K
i>6' @12» @2p'
1 1 1
Surface * ' >
6" Deep
T 18" Deep
.58K .55K .25K
i '
.67K ."58K .4K
Note: Velocities at 6" and 18"
below surface are averages
of 3 uncalibr-ated readings.
Surface velocities are
calibrated.
n
en p.
I rt
VO
-------
SECTIONAL VIEW
OF SURFACE CURRENTS,
BUBBLES AND SUB-SURFACE
CURRENTS NEAR AIR BARRIER
Current Z Line Current
Sub-Surface
Currents
Bottom
Bottom Dredged
by Currents
Generated by Air
Exhibit 10*
-146-
-------
s?
OCEAN
Air
Supply *
Float supported
cans at 3* depth
*
Cans react to
sub-surface
currents
o «
TEST BASIN
9:00 A.M. High Tide
Start of Test
OCEAN
Cans and floats
diverted by sub-
surface currents
t
Tide Ebbing
TEST BASIN
A.M.
T
Air
supply
All cans and
floats diverted '
past end of air
barrier
Tide Ebbing
at 1 K
TEST BASIN
11:00 A.M.
End of Test
Diversion Effect of
Sub-Surface Currents in an Air Barrier
-------
THE AK SKIMMER DESIGN
Hoisting
Bar
Wei
Table
SECTION A-A'
Gusset
PLAN VIEW
Exhibit 12,
-148-
Gusset
-------
PAGE NOT
AVAILABLE
DIGITALLY
-------
22 Skimmer Designs Studied in this Project
Identification;
"Separating" Skimmers
"Oilivator" Endless Belt
Golten Endless Belt
Dutch Shell Oil Scrubber
Welles Rotating Drum
Amoco Rotating Drum
"Mop-Cat" Rotating Drum
Earle System
Golten Rotating Drum
"Blotter" Skimmers
Johns-Manville Sea Serpent
Arabian Poly Mattress
Absorbent Float (Unidentified)
"Suction Nozzles"
Vacuum Tank Nozzles
Golten
Slickbar Manta Ray
"Separating Column" Skimmers
Norfolk Navy Yard
Slick-Sled
T.T. Skimmer Boat
"Floating Weir" Skimmers
Hammerli Agricoles, S.A.
Shell Experimental
Acme (Sunshine)
A.K.
Articulated Skimmer
Designed for this project
Exhibit 14.
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ARTICULATED SKIMMER (PROPRIETARY-U.5. GOVT.)
Discharge to
-Separating System
Oil/Water
Mix
Flotation
Chamber
Paddle Wheel Pump
Rotation
Oil Slick
Direction of
Plow
Skimmer moyes
against flow of
oil slick
Leading Edge
Skimmer
Independent flotation
for leading edge
Oil Slick
Water
-------
EFFECT OF OIL THICKNESS
0« EFFICIENCY OF WEIR SKIMMER
Water
:m. T
V 100%
Water
Discharge
Weir Set 2" Deep in A 3" Slick
Skims 100% Oil
1
__ " r
\ Oil/Water
-^-Discharge
Weir Set Level With Interface
Skims an Oil/Water Mix. Ratio
Depends on Wave Action.
A
Wate
~r~^_'' 10%
-rm\ Oil/Water
». Discharge
Weir Set as High as Possible Skims
More Water than Oil, Thus Removes
Oil Very Slowly.
Exhibit 16*
-152-
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ALTERNATE SYSTEMS FOR
RECOVERY, RECLAMATION AND DISPOSAL
Oil Slick
Clean Oil from a
Separating Skimmer
Transport Vessel
To Shore
Oil/Water Mix\from a
Non-Separating Skimmer
Separating Tank
on Skim Boat
\
Clean
Water
1
Clean
Oil
Pransport Vessel
ro Shore
I
Shore Based
Separating
Plant
hore Based Oil
efinery
jSludge Disposal |
Exhibit 17.
-153-
-------
SEPARATING TANKS
Skid-Mounted 280 Gal. Tank
4" Inlet Port
Air Vent
EXHIBIT
CleanV
Water
Drain
2 <§» Shorp Side 3000 Gal. Tanks
4" Inlet
Port
Drain
Ports
xJ_ECt
EXHIBIT
Clean
Water
Overboard
Clean Oil
Drain
alves
Exhibit 18.
-154-
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FLOATING TANK
PJ
VO
2" Loading Hose from Skimmer Pump
Air Vent
Water
Line
.2" Discharge Hose
Capped when not in Use.
A -
B -
Auxiliary Floats
To Support Deflated
Tank and For Visibility.
Float to Support End of
Discharge Hose.
Tank Dimension - 60'
- 5'
- 12'
Long
Deep - (Inflated)
Wide
Tank Capacity - 5000 Gallons
OPERATIONS INFORMATION ON FOLLOWING PAGE
-------
LOADING PROCEDURE
Pump oil/water mix into tank through Loading Hose. Open air vent as
necessary to relieve internal air pressure during loading. Close air
vent and cap loading hose when filling is completed. "
TOWING PROCEDURE
Tank tows easily if kept semi-inflated or fully inflated. If fully
loaded, tank will be awash and auxiliary floats are recommended so
that tank will be visible to other traffic.
X PRIMARY SEPARATION OP OIL/WATER CONTENTS
Moor tank in smooth water for 2 hours or more. Oil and water will
separate by gravity.
o DISCHARGE OP CLEAR WATER
Clear water can be pumped out through Discharge Hose, using any
available suction pump. Outlet from suction pump should be monitored
so that pumping can be stopped as soon as oil appears in the discharge.
PUMPING OF RESIDUAL OIL
After clear water is pumped out, Discharge Lines can be used to pump
residual oil/water into shore-based separating system for final
separation and disposal. Air vent can be opened during discharge if
needed, but this has not been necessary to date.
-------
AERIAL OBSERVATION PROCEDURE
FOR
REPORTING OIL SPILLS
Observation
of a
Suspected
Oil Spill
Radio Report to
Air Traffic Control!
Flight Service
Station or Control
Tower
Detailed report
to Communication
Station ready to
Copy.
Radio station
notifies nearest
Coast Guard
facility by radio
or land line.
Pilot or crew of Military or Naval Aircraft,
Scheduled Air Carrier or General Aviation
Aircraft observes a suspected oil spill.
Pilot reports "I have sighted an oil spill.
Can you receive my report on this frequency?1*
Pilot changes to frequency of station
equipped to copy, and gives location, size
of spill, local weather. surface areas
threatened by spill and other pertinent
information.
Coast Guard acts to notify officials in
area threatened, starts air or surface
investigation of report and cooperates
on execution of any Contingency Plan.
Notification to
Civil Agencies
Notification to
Government Agencies
>
Notification to
Personnel in
threatened areas.
1
/
Local Contingency Plans are activated to the degree necessary
for the situation.
Exhibit 21.
-157-
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Suggested Design for an
OIL POLLUTION WARNING POSTER
Note: This design could be used as an
International Oil Pollution Warning
Placard. It could also be mounted
on an anchored float at the site of
an oil spill. It could be made of
a self-destruct material which would
disintegrate when desired.
Exhibit 22.
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SYSTEM TEST - FUNNEL BOOM
Portland (Maine) Fireboat serving as Command
Post and Observation Platform during SYSTEM
TEST. Equipment includes Tow Boats, Fence
Type Booms used as a funnel, articulated
Skimmer (experimental prototype) pump barge
and fabric storage tank.
Exhibit 23.
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EFFECT OF WIND OR CURRENT
ON FUNNEL BOOM
Lead
Boat
Wind diverts
oil to down-
wind side of
funnel.
#2 Boat
Skimmer
Exhibit 24.
WIND AND CURRENT EFFECT ON SPILL
FROM OFF-SHORE OIL WELL
Path of
Oil on
Surface
Wind
Fall-out of
air-born oil
Current,
up to 5 K.
Exhibit 25.
-160-
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EFFECT OF AIR BARRIER CURRENTS ON A
WIND-DRIVEN OIL SPILL
According to literature on the subject, a thin film of
oil will tend to move across the surface of the ocean
in response to the lower level winds which are prevalent
in the area.
It is generally agreed that the oil will tend to move
at a speed of 3.8% to 4% of the speed of the wind above
it. (Effect of water current being zero.)
Floating objects, however, tend to float at the speed of
the current in which they are carried, wind effect being
zero.
If we assume an oil slick being driven West by a 30 Knot
breeze toward an air barrier which is generating a surface
current of 1.25 Knots in an Easterly direction, we find
that the speed of the oil slick toward the North is 4%
of 30 Knots or 1.2 Knots.
Therefore, we would expect the force generated by the air
barrier to stop the Northerly movement of the oil spill
at a point about 2* from the Z line of the barrier.
Note:
"Z" line of
Air Barrier
Surface currents from
Air Barrier flow away
from Z line in both
directions as shown.
*-?
1.25K
1.25K
1.25
Oil
Slick
Wind-Driven
West at
1.2K
1.25K
Wind at
30K
/
Force of Wind overcome by
current from Air Barrier*
Exhibit 26.
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Tri-X Pan Infrared
Aerial Photos October 9,1969 1350 EDT
Pen is positioned 200 ft off the pier head. Oil leaks in two places are more visible with Tri-X pan,
Pollution streak is seen in IR approaching from left of pen. Airplane shadows visible.
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