600281216
ESTS OF THE SHELL SOCK SKIMMER ABOARD USNS POWHATAN
by
H.VT. Lichte. V.. Bo-st. <^,c G.F. Smith
Mason & Hangar-Silas V±?on Co,, Inc.
Leonardo, New Jersey 07737
Contract No. 68-03-2642
Project Officer
Richard A. Griffiths
Oil and Hazardous Materials Spills Branch
Municipal Environmental Research Laboratory
Edison, New Jersey 08837
This study was conducted in cooperation with the
U.S. Navy
U.S. Coast Guard
U.S. Geological Survey
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
U.S. Environmental Protection Agency, anc approved for publication.
Approval does not signify that the cont:-nt£ nr; e.~sa-il\ reflect the vie.vs and policies
of the U.S. Environmental Protection Agency, nor does rr ention of trade names or
commercial orocucts constitute endorsement or recommendation for use.
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FOREWORD
The U.S. Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health and
welfare of the American people. Noxious sir. foul water, and spoiled land are tragic
Testimonies to the deterioration of our neru-a- environment. The complexity of that
environment and the interplay of its components require a concentrated and integrated
attack on the problem.
Research and deveJoDrnent is that reces^arv
involves defining the problem, measuring its irrir-oCt, and searcning for solutions. The
Municipal Environmental Research Laboratory develops new and improved technology
and systems to prevent, treat, and manage wastewater and solid and hazardous waste
pollutant discharges from municipal and community sources, to preserve and treat
public drinking water supplies, and to minimize the adverse economic, social, health,
and aesthetic effects of pollution. This publication is one of the products of that
research and provides a most vital communications link between the researcher and
the user community.
This report describes the performance testing of the Shell SOCK skimmer
aboard the USNS Powhatan. The tests were the first tests performed offshore by the
OHMSETT operating contractor. Further information may be obtained through the Oil
and Hazardous Materials Spills Branch in Edison, New Jersey.
Francis T. Mayo
Director
Municipal Environmental Research Laboratory
Cincinnati
MI
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ABSTRACT
An oil skimmer was tested in a controlled crude oil dumping off the New 3ersey
Coast in early 1980. The program was sponsored by the U.S. Navy, Director of Ocean
Engineering. Supervisor of Salvage through the Oil anc HcZcrdo~JS Materials Simulated
Environmental Test Tank (OHX'SETT/ ?r.rrage-"icy Technical Committee. V;embers oi
the committee included the United States Environmental Protection Agency (USEPA),
the United States Coast Guard (USCG) the United States Geological Survey (USGS),
the United States Navy (uSN). and Environment Canada. The tests were designed to
evaluate the Spilled Oil Cortarvr.rnt Kit 'SOCK- developed by Shell Development
Company. The skimmer had ~eer; c?^gr,ed as B physical attachment to an oil industry
work boat in a vessel of opportunity deployment mode. The United States Naval Ship
(USNS) Powhatan T-ATF fleet tug was chosen as a similar vessel and one that had an
oil spill recovery operations mode.
The test program is described, including the oil/water distribution and
collection system, deployment and retrieval of the SOCK, the onboard fluid
measurement, data analysis, logistics, weather and environment measurements, and
the Powhatan/SOCK interface. The light crude oil and ocean water collected were
stored aboard the vessel and decanted; the emulsified oil was later sold as waste oil.
Eight experimental crude oil dumps are described and analyzed. The sea conditions
varied from calm to 1.8-m significant wave heights. During the 6 days at sea, 50 m^
of oil were dumped, and the skimmer collected 32 m of oil.
The program is analyzed for future improvements to open ocean testing plans
incorporating oil skimmers with and without vessels of opportunity. This program was
fortunate to have available a skimmer that had extensive testing as a model,
seaworthiness testing on commercial work boats, and oil collecting experience in a
spill of opportunity.
A 16-mm color/sound film on this subject is also available; it is entitled, "Open
Ocean Log."
This report was submitted in fulfillment" of Contract No. 68-03-2642 by Mason
& Hanger-Silas Mason Co., Inc. under the sponsorship of the U.S. Environmental
Protection Agency. This report covers the period December 1978 to May 1980, and
work was completed as of 3une 1981.
v
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CONTENTS
Foreword iii
Abstract iv
r;g-ires vi
TdbJes vii
Metric Conversions viii
Acknowledgments ix
1. Introduction i
2. Conclusions and Recorrirrienoatjoris 2
3. Research Plan 3
4. Portable Test Facility 17
5. Spilled Oil Containment Kit 28
6. Test Description and Procedures 37
7. Data Collection 48
8. Laboratory Analysis and Sampling Plan 52
9. Data Reduction 61
10. Test Results and Discussion 76
References 79
Appendix - Participating Organizations 81
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FIGURES
Number Page
I Genersl area for proposed test sites 1 i
2 USNS Powhatan, bow view 18
3 USNS Powhatan. stern view 19
4 Fluid management diagram 22
5 Auto Loran-C data station 27
6 Sock mounting, starboard sice 29
7 SOCK, deck view irorr, stern 31
8 SOCK, view from bridge deck 32
9 Sock deployment from barge, forward outboard, starboard view 33
10 Sock deployment from barge 34
11 SOCK main deck layout on USNS Powhatan 36
12 Collection tanks I, II, III, and IV (partially hidden) 39
13 Daily weather record sheet 51
14 Centrifuge for oil/water analysis in Powhatan lab 53
15 Discrete sampling station 54
16 Diagram of discrete sampling pipe 55
17 Dipstick sampling station 57
18 Johnson stratified sampling on station 58
19 Grab sampling station 60
20 Wavetrack buoy at sea 62
21 The ENDECO wavetrack buoy 63
VI
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TABLES
Number
1 Typical properties of Tes: Oils Used at OHM^tTT .................... 8
2 Crude Oil Data and Composition of Naphtha Fraction ................. 9
3 Test Matrix [[[ 14
5 Ocean Water Sample Analysis ...................................... 52
6 Example Results ................................................. 59
7 Reduced Distribution Data ........................................ 65
8 Summary of Recovered Fluid ...................................... 66
9 Throughput Efficiency Combinations ................................ 67
10 Collected and Recovered Data Correlated by Test Number ............ 73
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LIST OF CONVERSIONS
METRIC TO ENGLISH
To convert from
Celsius
joule
joule
kilogram
meter
rneter
rneter2
7
meter^
meter-'
meterS
meter/second
meter/second
meters/second
meters/second
meters/second
newton
watt
ENGLISH TO METRIC
centistoke
degree Fahrenheit
erg
foot
foot2
foot/minute
footS/minute
foot-pound-force
gallon (U.S. liquid)
gallon (U.S. liquid)/rninute
horsepower (550 ft Ibf/s)
inch
inch2
knot (international)
liter
pound force (Ibf avoir)
pound-mass (Ibm avoir)
pound/foot2
Multiply by
foot-pound-force
pou'id-rnass (Ibm avoir)
foot
i-ich^
foot-
inch2
gallon (U.S. liquid)
liter
foot/minute
knot
centistoke
footS/minute
gallon (U.S. liquid)/rninute
pound-force (Ibf avoir)
horsepower (550 ft Ibf/s)
meter 2/second
Celsius
joule
meter
meter2
meter/second
meters/second
joule
meterS
meters/second
watt
meter
meter2
meter/second
meterS
newton
kilogram
pascal
i.OOO
7.374
2.205
1.549
2.642
1.000
1.969
1.000
2.119
1.587
2.248
1.341
E+07
E-01
E^OO
E-QO
E+01
E+01
E+03
E+02
E+03
E+02
E+00
E+06
E+03
E+04
E-01
E-03
1.000 E-06
tc = (tF-32)/1.8
1.000 E-07
3.048 E-01
9.290 E-02
5.080 E-03
4.719 E-04
1.356 E+00
3.785 E-03
6.309 E-05
7.457 E+02
2.540 E-02
6.452 E-04
5.144 E-01
1.000 E-03
4.448 E+00
4.535 E-01
4.788 E+01
VIII
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ACKNOWLEDGMENTS
A program of this magnitude and potential impact on spilled oiJ control
technology required a ;arge number of organizations and dedicated people. A broad
mix occurred of direct pa-Tic'p-tior: by gc\ err.merit facilities and private industry.
Appendix A lists these organizations contribjting on a perJodic basis.
The land- and ship-based teams from Mason i: Hanger-Silas Mason Co.. Inc.
performed an outstanding job. bringing ail their experience and kncv/ieoge to this
successful p-oject.
Roy Sea, John Farlow, Richard Griffiths, and Chad Doherty are acknowledged
for their timely and effective support. The USNS Powhatan, with its Master, Alex
Prieto, provided a safe and effective working platform. Robert Ackerman managed
the land-based support activities and Debra Watson managed the production of this
report.
IX
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SECTION 1
INTRODUCTION
Navy Directo' of Ocean Engineering. Supervisor of
'S:JPSAVL;, Naval Sea Systems Command has a responsibility tc promote oil spill
control technology. Also within the Navy is a new class of fleet ocean tug, T-ATF
166, which Incorporates the capabilities and design features of commercial offshore
industry tog/supply boats (Reference 1). The mission as a unit of the Mobile Logistics
Sjnnor; Force is ic salvage and :.a-;e in tow ships of the Fleet that are battle cmnarec
or nor.-oper&ijonal. Permanently Installed equipment onboard provides for wire rope
towing, synthetic hawser towing, quick reaction system for beaching/breaching
problems, mooring, firefighting, and dewatering. Other designated portable equipment
can be loaded onboard before additional missions for salvage, diving, and oil spill
recovery.
The U.S. Navy has an extensive inventory of booms and skimming equipment
that have demonstrated high performance and efficient deployment. Their interests
lie in looking to the future and to new spill equipment capability. They were
convinced by Shell Development Company that the Spilled Oil Containment Kit
(SOCK) (Reference 2) may be a candidate for a cost-effective, vessel-of-opportunity
system that could be deployed from standard offshore supply boats.
SUPSALV is a member of the OHM SETT Interagency Technical Committee and
as such requested the committee in December 1978 to listen to a proposal to
formulate a research plan to test a skimming system offshore using crude oil. The
committee membership included representatives from U.S. Navy Supervisor of
Salvage, (USN-SUPSALV), the U.S. Environmental Protection Agency, (USEPA), the
U.S. Coast Guard, (USCG), and the U.S. Geological Survey (USGS). The chairman is
the EPA representative from the Oil and Hazardous Materials Spills Branch, Municipal
Environmental Research Laboratory. The committee assigned the responsibility to
OHMSETT to research, design, deploy, test, retrieve, and report on the program. In
January 1979, Mason & Hanger-Silas Mason Co., Inc., operators of the OHMSETT
facility, drew up a budget for the Program.
Research began on existing permits and review of past experience. The only
significant recorded recent attempts were the soybean oil experiments with a U.S.
Coast Guard containment barrier and the small crude oil dumps for dispersant studies.
The OHMSETT plan initially considered testing the SOCK to be tested on a leased oil
industry supply boat off the New Jersey Coast in October 1979. A published survey
(Reference 3) indicated that there were 2750 vessels for hire or charter around the
world. We estimated that at least half of them could be considered for deploying the
SOCK. A closer evaluation indicated that only four would be within reason for the
program because of their cost, schedule committments, load capability, and
integration to our program. The next major decision was selection of a crude oil. A
1
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published survey (Reference 4) repealed 93 different types of crude oil in the \vorid
export streams. Analysis based on this and many other factors led us to confirm that
La Rosa and Murban should be primary candidates for the test oil, because their
physical properties are representative of export crudes.
The research program plan was completed and submitted by the L'SN to the
USEPA Region II Office, New York City, in May 1979 (Reference 5). Engineering was
continued in parallel to design, fabricate, test and depjoy a portable test platform
adaptable to vessels of opportunity for the SOCK. High priority was placed on a
versatile system deskn to be used in future testing at sea for most any skimming
esting.
* he pjar.ring continued ceipiie several diversions. The SOCK was loaned to
rtMEX ^Reference 6) curing portions of the 1XTOC 1 spill. The Dutch government
expressed interest by offering equipment and facilities on the North Sea for the
offshore tests. Te observed firsthand several cleanup systems at IXTOC I. We then
= ;d;rG the deployment at the F^,r~ah Arate spill of a recently CHN*S5TT-tes:ed
system. Troii/Dsstroil. and tried to quantify ITS performance on a vrise'-of-opportu-
nity 22-m (72-ft) shrimp boat.
In January 1980, the USNS Powhatan was selected as the dedicated vessel for
the experiments and the Permit was issued by USEPA (Reference 7). Hardware
designs were integrated to the T-ATF 166 class, and fabrication of the test equipment
began. A portable on-oeck tankage was also considered preferable for crude oil and
fluids storage. The at-sea schedule was fixed for mid-April 1980. The USCG offered
their cutter Reliance as an observation platform at sea. Communications were firmly
established with the Captain of the Port in New York City and with the Region II
USEPA administrator.
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SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
^is iest pr::g'an"; yJei'ed t.vo v.';:~.'ficir.t new unoer?ta-cings of oil soil
FJrst, a lar^ge qjan'.'ty o: .:rj:e oij ^-:-.s duHipec successfully to quantify
skimmer perfomrance in the ocvan environment. The second new understanding is
what constitutes a vessel of opportunity.
The SOCK svstem De"fordnance '^as outstanding under specific o^eratine
conditions. The best performance was y.^c>._irec during the mJd-;'rorn.ir;g of April 12.
1980. The sea conditions were considered sea state 2. The recorded wave heights
were one meter with five second periods. The wind speed averaged 8 knots, and the
Powhatan was moving into the wind and seas. The measured throughput and recovery
efficiencies of the SOCK were 89 and 93 percent, respectively. The relative wind-
driven surface speed was 1.5 knots. The crude oil recovery rate was 35 m^/hour. This
figure corresponds to 154 gpm, 220 barrels per hour, and 31.6 long tons per hour. The
slick encountered was 2 mm thick, and the SOCK had a preload of 3.8 m*.
At the same speed, but with rougher seas and thicker slicks, the performance
dropped significantly. The afternoon test was in 1.4-m waves every 3.7 seconds and
20-knot winds. The slick was 3.3 mm. Throughput and recovery efficiencies dropped
to 39 and ^7 percent, respectively, arid the crude oil recovery rate dropped 66 percent
down to 12 m^/hour. Other tests concluded that speeds of 0.75 knot and at 2 knots,
the performance was also degraded significantly. The eight offshore combined tests of
the Powhatan/SOCK dumped 50 m 3 of crude oil and the system recovered 32 m^.
The second understanding produced from this program is that such terms as
"vessel-of -opportunity" and "vessel-of -convenience" are misleading. If the spiller
wants to accept that terminology, he faces significant logistics problems, long waits,
and high costs. It is analogous to the misconception of many Jay people that there is
an abundance of empty barges and idle tugboats in every harbor in the United States
that could be used for spilled oil collection storage.
A great majority of oil industry work boats cannot independently go slowly
enough in the water while continually pulling low-drag force skimmers. A tugboat
must be astern to provide additional load, or the workboat operator must abuse the
engine system. This program was fortunate in having available a vessel with variable-
pitch propellers. The Powhatan could only use one engine and its bow thruster to
maintain the slow speeds with a steady heading.
This research program can produce a large quantity of recommendations based
on this singular experience that was extensively documented. The most important
recommendation, however, is that open ocean testing in the future should continue to
be limited to those devices that have progressed through the complete engineering
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cycle, ihey must hive been tank nested with oil and survived ope' ore an ?r-:-, worthi-
ness tests.
Before the SOCK tests, two spill-of-opportunity tests were made in the Gulf of
Mexico. There were 10 cays at sea, only two tests (in calm water), and fewer data (by
several orders of magnitude). We recommend that spill-of-opportunity testing be
given its own jurisdiction, research priority, and financial emphasis. Apparently,
weather and sea-state should be the only constraints. Instrumentation must be well
designed and tested. Deployment needs be planned thoroughly, and the equipment
must be sturcv and disDaicned on a tirr.eiv basis.
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SECTION 3
RESEARCH PLAN
GRAM PLAN
This program is based on experience and research from U.S. Government
Agencies and incorporates the latest technology in skills of oil on the near-coastal
waters.
Introduction
This test program was designed to evaluate the performance of the Shell SOCK
oil skimmer in an ocean environment. The plan proposed a test of the Shell SOCK by
collecting crude oils in the open sea typical of those which are transported on US
waters. The character of the crude oil selected for dumping is well documented in
field data from prior spill tests in the same geographic area (off the New Jersey
Coast). The program was estimated for twelve oil dumps, each with a maximum of
13.2 m3 (3,500 gal). A maximum of 18.9 m3 (5,000 gal) of oil will be left at sea. The
test plan was carefully designed to minimize resultant impact on the environment.
Program Justification
Skimmer design technology has diverted into several different approaches and
many of these in concert with "dedicated" vessels i.e., those designed or modified
specifically for spill cleanup purposes. Availability of these dedicated vessels has
often been a severe logistics problem, they are frequently costly, and storage of
collected fluids is burdensome. Concepts to date may be categorized into oleophilic
belts, vortex separation, rotating oleophilic discs, weirs, dynamic inclined plane,
oleophilic drum discs, streaming fibers with weirs, mops, paddle wheels, and various
combinations thereof (Reference 8). The forces at sea have been destructive and
degraded performance of most of these concepts.
It is believed that the Shell SOCK system proposed for testing represents,
overall, one of the most promising designs. If at-sea results with oil verify predicted
performance, it may also prove to be unusually cost-effective.
Test Objectives
The overall objective of the program is to embark on a field test operation
utilizing the quantitative and qualitative data available from industry and Federal
Research and Development agencies to document and demonstrate the capability of a
spilled oil skimmer collecting crude oil from the open sea.
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In trie past fifteen years. -:,.- arch has resulted in a large number of individ'jaj
studies and development has produced several hundred skimmer concepts and patents.
V Engineers have tested skimmers in clean waters without oil. followed by tests in a
Jarge dedicated test tank collecting simulated crude oils. It is recognized that
skimmers provide only one of several options to spill control and these may be
complemented with or replaced by dispersants, especially offshore. Several different
types of advancing skimmers have been marketed to industry and governmental
agencies but none have been adequately documented in cleaning actual oil spills.
Private contractors, cooperatives and the U.S. Coast Guard Strike learns are
frequently used for spill cleanup but a great deal of factual data still needs to be
accumulated as the bas.'s for f;_:tu-e c:es':m and progress. Spi.Us on the water (whether
immediate :mnce,ms for o:cpe:t\. the envir omment. and r.afetv. Unfortunately this
> r j * j
collectin data tc benefit desin and oeration of the skimmers.
Tne results of this roram will provide new and
covery.
The program will produce a substantial benefit to a number of federal agencies
including the USEPA, the USCG, and the USN and it will provide new and definitive
technicial data to assist private industry in meeting spill control and cleanup
responsibilities. The skimmer system is one which is expected to be exceptionally
cost-effective and the test program is needed to produce an actual discharge of oil at
sea under controlled, well defined conditions. The SOCK system has been developed
over a number of years, beginning with a theoretical concept followed by model
testing in wave/tow tanks and full-size testing in tanks with oil. Subsequently,
seaworthiness tests were conducted in the ocean without oil. Because available test
tanks are too small to completely evaluate the capabilities of the system in full-scale,
actual environment mode and because no other alternate means for conducting the
research are available, this program is necessary to prove the devicein sea conditions
with oil.
The program will allow transference of laboratory-proven experience into a
field situation to evaluate oil skimming performance. In addition, field operations will
allow detailed records to be made of operational features such as the ease of
deployment, on-station operational procedures and retrieval of the skimmer system.
The basic elements of study will include:
(1) selection and dockside outfitting of a single vessel of opportunity typical
of those normally available in petroleum producing areas.
(2) deployment of the skimmer from its transport position to its oil-
collection position.
(3) measurement of the weather/sea conditions on station and the sea-
worthiness of the skimmer/boat in that environment.
(4) creating an actual crude oil spill for the skimmer/vessel system to
collect. This will be accomplished by first releasing a small preload
quantity of oil directly in front of the skimmer's entrance followed by a
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SUCK equ;valent TO t~at lively to be e-icounterec m continuous operations
daring a spill.
(5) measuring the skimmer's actual performance in collecting oil, incJua'ing
throughput efficiency, recovery efficiency, and recovery rate in increas-
ingly difficult combinations of wave and speed conditions.
(6) managing of collected fluids (oil and water) on the vessel.
(7) retrieval of the skimmer to the vessel of opportunity and subsequent
return to port.
(8) equipment dealing and environmentally safe disposition of the collected
fluids.
(9) production of a written report of the program and resulting data,
including a documentary film.
TEST PLAN
The plan is designed to ensure minimum opportunity for an accidental spill. It
incorporates the best known resources of engineering and equipment for the remote
operations.
Background and Previous Research
The OHMSETT Interagency Technical Committee (OITC) membership currently
represents the USN, USCG, USGS, and the USEPA. The OITC has jointly sponsored
skimmer testing/development at OHMSETT for the last four years to discover cost-
effective solutions to oil spill cleanup technology. To date, the OITC has jointly
conducted 16 weeks of intensive performance tasks with oil on eight different types of
skimmers. This test program is intended to "bridge" the effort between designer and
user and to integrate performance efficiency with the logistics of deployment,
operation, and retrieval.
Under OITC sponsorship and control, 730 m3 (192,940 gal) of test oil has been
spilled in tests at OHMSETT using three refined naphthenic grades of different
viscosities to simulate the major span of crude oil properties. OHMSETT, in the past
five years has dumped 6,000 m3 of test oil. Table 1 illustrates typical properties of
the test oils, all of which have Jess than 0.24% sulfur content.
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J.£ST_pILSJJSED_AT_ OH\[SET T
Liht
Specific Gravity
Viscosity, (cSt @ 75°F)
Surface Tension (dynes/cm)
Interfacial Tension. Saltwater (dynes/cm)
Gravity, °API
Density. Ib per zal
Four Point, °F ~
Aniline Point, op
Flash Point, °F
0.89
9.0
32.9
27.0
26.4
7.46
-50
131.0
225.0
0.92
200 . 0
33.5
26.4
20.3
7.76
-20
156.0
350.0
0.94
1300.0
34.4
26.3
18.4
7.S6
-5
168.0
390.0
Trie only documented (Reference 14) intentional offshore spills employed TO test
oil collection techniques utilized soybean oil (27.000 gal in the Gulf of V.exico off
Tarnpa, Florida and 50.000 gal in the Pacific Ocean off Point Conception, California).
While possibly simulating the hydrodynamic properties of a single crude, this test oil
could not model other, more important, chemical properties peculiar to other crudes
commonly shipped in U.S. waters. The specific gravity of the soybean test oil is so
high that only seven of the 93 popular exported crudes throughout the world have equal
or higher values. Tank testing technology improved following the soybean oil tests,
initially by using paraffin-based refined oils and finally progressing to the naphthenic
oils. Nevertheless, these latest improvements cannot simulate the chemical properties
of raw crude stocks.
Crude oils should be avoided in test tank facilities for many reasons. Safety of
personnel and property is paramount in that flammability and storage containment
requires expensive precautions and presents a danger to the land-based environment.
Refined test oil entrainment in large saltwater tanks has a straightforward engineering
filter design solution and refined oil does not weather or form a mousse like the
typical raw crude stock. Emulsions of crude oil and saltwater are difficult to break
and thus economy is also a benefit in using the refined stocks. Reclamation and reuse
of these oils is technically straightforward. Equipment cleaning and service life is
much better with the known test oils. The laboratory environment can predict
hydrodynamic response but not the chemical response that so often is reported on real
spills where synergism displays additive effects different from singularly tested
phenomenon.
There are perhaps several hundred test tanks in the world that can generate
wave motion for studying vessel response on a sub-scale or model basis; however, only
a few can deploy oil for skimmer studies. None can generate the combination of
random waves, tidal currents, and wind forces to be experienced by a full-size vessel
collecting spilled crude oil on the open water. To date, the OITC program has
conducted 483 tests in waves with oil in EPA's OHM SETT test facility at speeds from
one-half to 6 kt. The waves vary from one-half to 4 ft high, and include harbor chops,
confused seas, and wave periods between 1.5 and 4.0 seconds. The
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Committee, with its breed-base vD,:-~:sorship. is constantly being advised. consulted and
supplied Information from spill equipment users. This offshore lest program is
designed to answer most of the users' needs and provide data not otherwise obtainable
by industry.
Test Oils
The La Rosa and Murban crude oils to be used for this offshore test program
were selected based on (1) rank in the 93 such varieties currently in the export stream
and (2) previous offshore research spills in the same geographic location. The
characteristics and composition of These TWO crjdes are indicated in Table 2. An
V,A-143 provides a program opportunity for
newer hardware and
logistics data for removing the same Type of spilled crude oil from the ocean. Crude
oil is one of the constituents listed in ^0 CFR 227. 6(a) 4, "Constituents prohibited as
existing Ocean Dumping Permit N
other than trace contaminants".
owever
the rohibitions and limitations of this
section do not apply lor tne granting of researcr }
rendered harmless by physical, chemical, or bioio;:
its if the substances are rapidly
processes in the sea.
TABLE 2. CRUDE OIL DATA AND COMPOSITION OF NAPHTHA FRACTION
Crude Oil
API Gravity @ 15.6°C
Sulfur (wt. %)
2Q4°C minus fraction
Benzene
Toluene
Cg Aromatic
Cg Aromatic
CIQ Aromatic
C\ i Aromatic
C]2 Aromatic
C|3 Aromatic
Naphthalenes
Indans
Total Aromatics
Paraffins
Cycloparaffins
Dicycloparaffins
Total
La Rosa
23.9°
1.73
11 vol. %
Percent by Weight
0.6
2.0
3.4
2.7
1.3
0.5
0.2
0.1
0.0
0.5
11.3
46.7
38.3
3.7
100.0
Murban
39.0°
0.82
19 vol. %
0.7
2.6
4.6
3.9
1.8
0.7
0.2
0.0
0.0
0.4
14.9
65.8
17.5
1.8
100.0
It is estimated that nearly 70% of the exported crudes will fall between the
range of the API gravity of the La Rosa and Murban crudes. Only 31% of the crudes
have a pour point greater than freezing temperatures. Weathering tests of La Rosa at
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OHMSETT for 14U hours in saltwater and waves showed a slight increase in specific
gravity, an order of magnitude increase in viscosity, a slight decrease in surface
tension and a 50% drop of interfacial tension.
Skimmer
The Spilled Oil Containment Kit (SOCK), designed by Shell Development
Company, has been selected for this program. Shell Oil Company reports development
began on the device six years age as a solution to the high cost of fast current
skimmers on dedicated vessels and to ado-ess acceptable performance in realistic
ocean wave conditions. A o'-e-e'^r.th sraie rrode: was tank-tested to study work boat
hyd'odvnamic actions and a o"i£.-'-,sif sraie -r.ode] uas bjilt and tested for oil/water
interactions. The Gulf of Alaska Clear;-up Organization (GOACO) then began
sponsoring a program to build and test a full-scale prototype model, and the pumping
system has been tested successfully with debris, ice, and heavy arid light test oils. The
rjl'-scaJe prototype has been tested for seaworthiness alongside work boats in the
Gaiveston, Texas area of the Gui: of Y-exjcc ^r|C '^>~ Port Hueneme. California area in
the Pacific Ocean. Emphasis on. and modifications in deployment, seaworthiness, and
retrieval in all development test programs has produced a viable integrated package
for easy, quick attachment to many vessels of opportunity capable of withstanding
four foot seas. Recovery efficiencies are estimated at greater than 80%.
Shell Oil also reports SOCK's unique design responds to realistic ocean wave
conditions by dampening the oily surface with a flexible curtain as opposed to using a
rigid shallow-draft dedicated vessel hull. Compared with 16 existing skimmers in the
world market, the cost and scope of deployment indicates promise as the most
favorable offshore crude oil test candidate, based on skimmer cost to recover 60% of a
7,570-m^ (2-milIion gal) spill. The quick response time resulting from the ability to be
used with a vessel of opportunity (as opposed to a dedicated vessel) makes the SOCK
even more attractive.
Test Site
The test site (identified in Figure 1) was selected to coincide with prior tests of
the same crudes and to benefit from other experimenters' data. This test program will
be scheduled so as not to conflict with other tests which may be planned in the area.
In selecting specific sites for conducting the proposed controlled spills, the principal
consideration was to minimize the chance that the oil could drift to shore or into any
environmentally sensitive area. Additional criteria applied in the selection process
included: (1) avoidance of areas of high activity such as shipping, commercial and/or
sport fishing, etc.; (2) water depth sufficient to assure that no spawning areas are
contaminated; and (3) a shore-to-shore test area distance compatible with transit and
on-station times of work boat and support vessels. Alternate test sites are considered
unacceptable due to their inability to conform to the above criteria.
The general area proposed for conducting the test is within the New York Bight,
and lies on a line extending generally southeast of Sandy Hook at a distance of 25 to 50
nautical miles.
The surface drift currents in this area are small (1/10 to 1/4 kt) and set
generally to the south. During the proposed test period (April, 1980) weather
10
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Shore
,
Long Island Sound
New York
Nsntucket Navigational Lane
Shore Line
New Jersey
General Area of Tests
Figure 1. General area for proposed test sites.
%**«
11
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records indicate the prevailing winds will be westerly. Observations of oil spills have
indicated that oil on the surface will move at a speed and direction that is the vector
sum of the water velocity and a fraction or percentage of the wind velocity. Thus,
when conditions are normal, the oil spilled for research purposes will tend to move in
approximately a southeast direction; that is, away from the land and out to sea. If
these normal, favorable conditions do not prevail, test spills will be delayed pending
acceptable changes in the weather.
The proposed test area is located near the Hudson Shelf Valley leading to the
Continental Shelf, providing water depths in the range of 40 to 80 m (approximately
131-262 ft, or 22 to ^ fathoms). Such depths will be more than adequate to assure
that the spilled oil will not contaminate the bottom sediments.
The U.S. Coast Guard has established three traffic separation zones leading into
Ambrose Channel and the ports of New York and New Jersey. These are identified as
the Barnegat. Hudson Canyon, and Nantucket navigational lanes and are shown in
Figure 1. The area under consideration within which the test site has been selected.
has been located so as TO be ooiside the navigational lanes. Because oi this, it should
be possible to avoid the bulk of commercial shipping traffic.
Test Procedures on Station
There is s. specific order of procedures to follow that interact to provide
an effective test program.
Preliminary Actions
The actual skimmer performance test will begin after the wind and sea
conditions are confirmed and the water sampled for baseline conditions. Site location,
communications, safety, and ancillary equipment will all be checked to insure that
they are in proper order.
Skimmer Deployment
The powered contingency Zodiac boat, MonArk launch, or MARCO Skimmer will
be deployed in the water to its starboard position alongside and amidship of the work
boat. The SOCK boom-skimmer will then be lowered from its shipboard position to the
water and moored in position to accept dumped oil from the work boat.
Seaworthiness
A practice deployment will be made to insure launching and retrieval compati-
bility of the SOCK, Powhatan, and fluid management systems. The work boat will be
steered into the wind and current at slow speed, increasing in J4-kt increments to 2.5
kt. Rigging and boom-skimmer response integrity will be observed in both head and
overtaking seas.
Preload Capability
The La Rosa crude oil will be dumped during the first test series. Murban crude
will be used for the last. A metered quantity 1.89 m^ (500 gal) of crude oil will be
12
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deployed frorr, the work boat jpsfia-n from the boo"-skirri!T;er at a rate of 6S m-Vnr
(300 gpm) with the forward speed at 1 kt ca jsing s 5 mm thick slick herded with water
jets into the skimmer's mouth. The boat will maintain course and speed for several
minutes to assure there is no excess oil loss from the skimmer.
The test will then begin. After the test and all data have been collected, speed
will be increased by K kt. Another preload of 1.89 m3 (500 gal) will be deployed for
the SOCK to check for excess oil loss and seaworthiness. If all functions are working
properly the speed will be increased in quarter kt increments to 2.5 kt. The boat will
maintain course and speed for several minutes to assure there is no excess loss from
the skimmer. The test will then begin, increasing speed until a definite oil loss is
observed. These tests in overtaViing seas will be repeated in an abbreviated fashion in
head seas arid with the '.'urban crude cil.
Test Procedu-es
Maintain speed,
deploy 1.85 rn3 (50C gal) preload test,
maintain course and speed for several minutes,
check preload for excess loss of oil,
deploy oil slick at 68 m^/hr (300 gpm) for 10 minutes,
collect data,
increase speed by Yi kt,
deploy 1.89 rn3 (500 gal) preload,
check preload for excess Joss of oil,
increase speed by % kt,
check seaworthiness and for loss of excess oil,
deploy oil slick at 68 m^/hr (300 gpm) for 10 minutes, and
repeat appropriate steps
The tests were originally planned for runs at 1,2, 3, and ty kt with seaworthiness
and preload checks at 1, 1.5, 2, 2.5, 3, 3.5, and b kt. Shell's more recent observations
suggest these speeds are too fast and should be reduced to quarter kt increments up to
2.5 kt maximum.
Performance Efficiency
The skimmer preload is required to keep the multiple oil suction ports
collecting pure oil instead of unnecessary sea water that would render onboard
13
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collected fluids storage inefficient. Performance efficiency testing will begin with a
1.89 m3 (5QG gal) preload at a 1 kt speed, then deploying an oil slick from the work
boat at 68 m^/hr (300 gprn) for 10 minutes. The test matrix for the twelve tests will
be as indicated in Table 3.
TABLE 3. TEST MATRIX
OIL
LA ROSA
MURBAN
Speed
(kt)
0.75
i.OO
1.50
2.25
Overtaking
Seas
X
X
X
X
Head Seas
X
X
X
Overtaking
Seas
X
X
Head
X
X
seas
Two tests will be performed with La Rosa in head seas at 1.5 ktone with the
standard 68 m3/hr (300 gprn) oil slick and the other with 37 m3/hr 065 gpm). With a
fixed oil distribution rate (300) and fixed oil/water removal rate of 75 m3/hr (330
gpm), the oil slick thickness will vary from 1.25 mm to 5.0 mm depending on work boat
speed. .Metering of crude oil distributed, balanced with metered fluids (oil/water)
recovered on the work beat will be used to calculate the performance efficiencies and
rates. Throughput efficiency is the ratio of oil recovered to that presented to the
skimmer. Recovery efficiency is the ratio of oil recovered to the fluids recovered
(oil/water). Recovery rate is the oil recovery rate measured in gal per minute.
Fluids Management
Crude oils will be stored separately on the deck of the work boat in closed
seaworthy containers. Distribution of the oils will be channelled through flow meters
and cross checked with volume measurments. Collected fluids will be metered,
aliquots taken to determine proportion of oil/water staged through the SOCK, and then
transferred to the deck storage tanks. Small volumes of crude oil lost under the SOCK
during specific tests will briefly surface and then be caught, mixed, and dispersed due
to the work boat propeller wash. Fluid recovery samples from the skimmer will be
analyzed after each test and calculations completed before the next. Gross volume
figures indicate that the 159 m3 (42,000 gal) of crude oil will result in recovery fluids
volume of 200 m3 (53,000 gal) oil and water at 80% recovery efficiency (RE), 318 m3
(84,000 gal) at 50% RE, and 530 m3 (140,000 gal) for 30% RE.
Skimmer Retrieval
The transfer pumps and piping system will be purged, capped and the fluids
collected. The boom skimmer will be retrieved by its integrated rail/crane system,
cleaned with fire hoses, and stored. The support boats will then be retrieved and
stored.
-------
Flotilla Maneuvers
Historical sea/weather conditions are utilized to produce the scenario in the
proposed general test area. The surface rectangular envelope (see Figure 3), will be
five miles wide and 20 miles long with major axis ESE, between the outer boundaries
of the Barnegat and Hudson Canyon navigational lanes. This is based on worst
conditions with wave crests parallel to NNE/SSW. Overtaking sea tests will begin in
the western most section of the envelope. One hour will be spent on station rigging,
deploying, and confirming sea/weather conditions. Then 15 minutes of upwind
seaworthiness tests (0-2.5 kt) will be performed, followed by four one hour downwind
performance efficiency tests at speeds of 0.75, 1.0. 1.5 and 2.25 kt. The six hours
required for these fiotilla maneuvers should ?.pan 11 to 2C rniies straight line travel
distance. Retrieving, cJirig-irig. and cleaning will take an ^oditional hour before
returning 10 po^t. The second day at sea will begin in the eastern most section and
move WNW, with resulting peac'stas. The last day will be a combination of head and
Schedule
The combinations of at-station maneuvering, safety precautions, and onboard
oil sampling will require three test days at sea with approximately four test spills per
day each requiring an hour's time. Each 10 hour day will consist of traveling to
station, deploying the SOCK, running tests, retrieving the SOCK, and returning to
port. No tests will be commenced after 2:00 PM local time (1900 Greenwich Mean
Time) in order to ensure adequate daylight to cope with any complications that may
develop. Additional oil clean-up capability will be on site during all test operations.
Safety
Safety practices will be observed at all times and conform to all federal
regulations applicable both offshore and dockside. The captain of the work boat will
be in charge and thoroughly cognizant of the test program for close coordination with
the test engineer, vessels in the flotilla, and the observer vessel. All participants and
authorized observers will be required to follow safety regulations.
Communications
In addition to normal marine communications equipment, the flotilla will have
mobile radio capability. The command station for the entire operation will be the
bridge of the work boat. This central location allows for quick response to any and all
problems which may arise. Fixed and portable radio communication will be established
so as to avoid interference with other radio frequencies.
SAFEGUARDS AND CONTROLS
The planning for the test has been a cautious approach to experimental
procedure so as to minimize environmental impact. The detailed cautious planning is
evident in the site characteristics, monitoring and control, and contingency measures
of the experiment.
15
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Site Characteristics
The proposed test site is more than 20 miles from nearest shore.
The oil siick will travel seaward.
Water depths are 40 TO 80 m.
Outside navigational Janes.
Impact to environment ;; > '.all.
V^onitorJTiE and Control
Weather conditions and forecasts will be consulted before beginning every lest.
Upon determination of satisfactory weather, the command station will ensure there is
no conflict with other marine activities within a specified radius. A small amount of
oil will be preloaded into the SOCK to ensure no excess loss of oil before the
experiment begins. If there is indication of large loss of oil, the experiment will not
begin. Complete communication with all vessels will ensure full control over the test
procedure. A pump will be used to spread the oil and it can be stopped at any moment
should a problem situation warrant such action. When in the course of an experiment,
excess loss of oil is noticed either by the bridge spotter or by the spotter at the rear of
the work boat, the experiment will be discontinued.
Contingency Measures
An additional contingency force will be available for an as-needed basis. This
includes one observer vessel, a MonArk launch, two small maneuverable work boats
(Zodiac), and an additional skimmer vessel (MARCO V). The distance from shore is
approximately 20-30 miles and emergency help can be summoned immediately.
At all times during the proposed test, a combination of monitoring activites will
be aimed at controlling test operations to assure potentially adverse conditions are
avoided. Before any test is allowed to start, command station will conduct a
reconnaissance of surrounding waters to ensure no conflict with other marine
activities. Continual monitoring of the National Weather Service forecasts, marine
weather broadcasts, and Coast Guard channels will ensure complete up-to-date
information on winds, meteorlogical, and sea conditions. In the event that a slick
presents potential adverse affects, the test vessels and contingency force will proceed
to the slick and employ appropriate measures until the slick is picked up, dispersed,
diluted and/or poses no threat.
16
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SECTION 4
PORTABLE TEST FACILITY
USNS POWHATAN
This T-ATF 166 Class ship is a new class combining the capabilities of the U.S.
Navy's tugs, ATF's, and commercial offshore tug/supply boat (Figures 2 and 3). It is
manned by a civilian crew of the Military SeaJift Command (MSC) and a Navy
communications team. The normal complement is 16 mien from MSC and 4 Navy
communication men. There are good accommodations for 20 additional men as
transients to support portable equipment missions.
The ship utilizes twin diesel drive supplied through separate shafts to control-
lable pitch propellers in nozzles. Commercially proven equipment is installed
throughout the vessel. The vessel is 226 ft long, 204 ft at the waterline, beam width
42 ft, draft of 15 ft and full load displacement of 2260 tons. The free route speed at
design waterline and 80% ship horsepower is 15 kt, cruising speed is 13 kt, and
optimum towing speed is 6 kt. The vessel forward speed was controllable in 0.1 knot
increments at low speeds. The endurance cruising range is 10000 miles. Ship power
includes two 3600 brake-horsepower (BMP) diesels, a 300 horsepower (HP) bow
thruster, and three 400 kW diesel generators.
Permanent equipment on board includes a 10-ton crane telescoping to 64 ft, a
towing winch capable of holding 500,000 Ib, a traction line machine capable of a static
line pull of 400,000 Ib, a permanent capstan capable of 30,000 Ib at 20 ft/min, a 9,000-
Ib MOORFAST type anchor, two combination vertical capstan and anchor windlass
units, each capable of 27,000 Ib pull at 20 ft/min, a 24 ft aluminum workboat powered
by 4-53-N Detroit Diesel, a towing bow, a stern roller, norman pins, bulwark rollers, a
tow wire guide, and two small portable capstans capable of 5,000 Ib pull at 20 ft/min.
One unusual feature is a main deck bolt-down grid pattern. It consisted of threaded
recessed sockets every 2 ft (1-in, eight UNC threads) in the clear deck area rectangle
of 38 ft by 88 ft. The allowable deck load was considered 300 tons for transient
equipment.
ORGANIZATION
The integration of the skimmer test program and portable test facility to the
USNS Powhatan was based on minimizing the physical interface.
The master operated the ship in accordance with MSC standard operating
procedures. The senior member of the transient crew was in command of the transient
crew and the oil dumping operations and equipment as an agent of the U.S. Navy. The
transient crew was grouped into ten for test operations, two for environmental
support, three for skimmer operation (launch and retrieval required three extra from
17
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Figure 2. USNS Powhatan, bow view,
18
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-rz:^ ! V vQ
£jt V^**r|-i ^*Tf t-i^-^-i-SiSWi!**-*1***1*^"'-^^
i, 1, f~#v;r|.-.
^JU^-HM-"/*-'
^0-*M|ltv|f ^
< J^ii5|*t?;feiJ^^^^;^
, 4, .V"iB-*jy-""rJ|
^&4C:M^fe:Jafe^--^^
-3BJ
j
Figure 3. USNS Powhatan, stern view.
19
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the test operations group), three OITC observers, and one operator for the MARCO
contingency skimmer. Another group of transients was periodically onboard as official
'** observers. A land based crew of 11 supported ship loading, special supplies, and base
station.
TEST EQUIPMENT
Most of the portable test facility for deploying on the Powhatan was designed
and tested at OHMSETT based on six years experience of testing in the tank and the
most recent experience of testing in offsite spills-of-opportunity. Thirty-one short
tons of equipment was transferred to the ship. The basic elements of the shipboard
facility were:
large storage containers for crude oil and collected sea water (6)
slick generator (deployed at sea)
fluids distribution manifolds (3)
gasoline engine hydraulic power pack (1)
water jet slick control system (deployed at sea)
gear pump for crude oil distribution (1)
air-driven double-diaphragm fluid transfer pumps (2)
crude oil, vane-type totalizer flow meter (1)
tank sounding instruments
venturi meter for collected fluids (1)
miscellaneous measuring tools and gauges
acoustic flow meter for collected fluids (1)
flexible hose, fluids transfer (350 ft)
tool house, spare parts and tools
.
video cameras and playback equipment
photo equipment, 16-mm motion picture and 35-mm stills
chemistry laboratory, oil/water separation analysis
environment measuring laboratory, waves, current, weather
automatic Loran-C tracking, position, depth
20
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special -cdio ccmmur.i-zaTion equipment
cleaning equipment and sorbents
detailed library of engineering calculations
detailed data-gathering manuals and sampling procedures
detailed onboard calculation procedures with contingencies
\vel--treined and supervisee transient crew
property management procedu-es
detailed safety program
spill prevention co't-ol and ccuniermeasures pjan
recreation plan
The portable test facility was capable of storing 11^ m^ (30,000 gallons) of
fluids on each cruise. The distribution system could dump test crude oil at a rate of
127 m^/hr (558 gpm), higher than the skimmer capacity and could be accurately
throttled to lower rates simulating thinner slicks. All skimmer collected fluids
brought aboard could be monitored. All measurements and test data could be
evaluated on station to produce preliminary performance results.
Dockside support was vital to the portable test facility. This program utilized
the deepwater pier located on Naval Weapons Station Earle at Leonardo, N3. A 70-ton
crane was used for lifting the SOCK equipment. Tractors were required to move large
equipment on flatbed trailers and 19 m^ (5,000 gallon) fluid tank trailers. Each late-
night docking required offloading of the crude oil and sea water collections of the day.
Test crude oil tanks had to be filled with fresh crude each evening.
FLUIDS MANAGEMENT
A flow diagram best describes the fluids management and includes integrating
manifolds, sampling piping, storage tanks, and pumps for three separate floating sea
platforms. Figure 4 illustrates symbolically the basic elements and connections of the
platforms. Designator legends are "M" for manifolds, "S" for individual sampling
station, conventional pump symbol, and lines representing piping and dashed lines
circumscribing floating platform limits. The piping system was designed to remain
intact once onboard, and not to be opened except for emergency repair. The 23 unique
sampling techniques are discussed in detail later in this report in regard to skimmer
performance. Some, had a primary function to monitor crude oil as designed in the
research plan and permit constraints. All crude oil measurements were to be at least
redundant. For example, crude oil loaded onboard for each tank was quantified with
two dipstick measurements and a totalizer meter. Crude oil dumped to the skimmer
was quantified in the same way. Crude oil collected by the skimmer was measured for
total and rate, then evaluated for water content and stored in tanks. Low skimmer
performance could cause high water content settling in a few instances. Decanting
21
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r
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ico
r'
i
c
i
ir^n rnr,,
i I _J L J I
I
L
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co
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o
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5
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i ^
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22
-------
water at sea was to be monitored with grab samples and dipstick rneaure'r.ents,
totalizer meter, and an oil/water separation chemical analysis.
Details not shown in the previous flow diagram represent an extensive piping
design consisting of 36 valves, 15 skid-mounted platforms, three at-sea floating
platforms, and six active flow meter instruments.
STABILITY AND TRIM
A weight program was used to control and monitor the equirnent impact on the
Powhatan's stability and trim. The maximum deck cargo load was tabulated to be 41
]ong tons, plus 18 long tons of fluid for each of the six collection tanks. The Research
Program die not require more than four full tanks, in the worst case 113 static long
ions onboard. The comparisons of metacentric height and draft data for the Powhatan
(Reference 11) were made by Hydrounatics Incorporated (Reference 12). While we did
not expect to skim oil in 12 foot seas, we had to prepare the high gravity joads on the
main deck to withstand pounding seas. The program also depended on the ship's crane
which has restricted operation for high deck loads and sea conditions. The calculations
to account for heavy seas were made with a 159.6 ton load in the dynamic mode.
Detailed results contained in the previous references indicated the ship would be a
stable platform to deploy the experiment. The reader is advised that the ship's master
is the authority on the stability and trim, and the research program estimates were
made to ensure a reasonable impact on the Powhatan.
MEASUREMENTS AND ANALYSIS
Redundancy
Redundancy was designed into the measurements and analysis section of the
portable test facility. All members of the transient crew were assigned tasks for
making visual estimates and/or reading gauges. Specific detailed responsibilities were
delegated to only 14 members. There were 12 onboard data retrieval stations, three
moored buoy stations in the vicinity, and two land-based stations. The majority of
measurements were considered active instrumentation. The passive measurements
were oil and water samples collected for chemical evaluation and photographic film to
be developed.
Data Management
Data management was accomplished by assigning specific responsibilities to
transient crew members and by distributing a 'printed set of data records forms with
instructions that included contingencies and sample calculations. Instantaneous audits
were made through radio contact with key stations and playback of portable audio tape
cassette recorders throughout the Powhatan and other vessels in the flotilla.
Photography
Photography and video records were designed for several purposes. A video
camera was mounted on the top fire-fighting platform for constant surveillance of the
main deck activity which included all deployment and retrieval, oil distribution to the
water, water jet performance, skimmer reaction to the waves and forward speed, and
23
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finally the SOCK iosses forming a slick. A roving close-up second video camera was
used to record individual operations and skimmer performance. Voice-over sound and
instant portable playback options were utilized. Motion picture and still photography
were u:-.ed for high resolution and measurement records. These cameras were always
roving and deployed near operations and skimmer loss stations. Specific phases of the
test program required the visual records to be made from other vessels in the flotilla
and one cameraman would be deployed from the Powhatan. Underwater photography
capability was considered but not fielded for these tests at sea.
The basic elements were:
cameramen (2)
color video cameras (2)
B/W video camera (1)
color video portable record/playback with sound (2)
16-rnrn motion picture cameras (3)
35-rnm SLR still cameras W
photo/video cinema lights (2)
lenses, mounts, and support equipment
Visual recording of the at-sea tests produced 14 hours of video tape, 6,000 ft of
motion pictures, and 1.600 still photographs/slides.
Surface speed
Surface speed measurements were made with wood chips, two men, and a
stopwatch. The fir wood chips were half-inch slices of 2x4's for a stable low wind
profile and painted with fluorescent glowing yellow-orange for visibility. The thrower
was stationed amid-ship exactly 100 ft from the timer stationed near the stern. The
speed measurement was repeated several times for each skimmer test and considered
the wind-driven sea surface current. A typical series of measurements would repeat
within 0.05 knot. Forward speed of the Powhatan was set by the master as suggested
by the senior member. The bridge doppler meter readout was in a nixie light digital
display, XX.X kt. Once at speed, the one-tenth digit rarely would cycle in Jess than 30
second periods. A wood chip speed measurement was then made. If it is was within
0.1 knot of the planned test speed, the measurement would be repeated and the test
dump sequence began. If not, the Powhatan would increase or decrease speed and
wood chip was tossed again. The reading difference between the doppler meter and
wood chip did vary +/-0.2 kt depending on the sea state.
Fluids Quality
Oil water ratio was determined in the portable chemistry laboratory that was
set up in the Powhatan's machine shop. These passive samples were collected from
various sources during each test at sea. A series of 100 ml discrete samples were
taken from the SOCK pump discharge in prescribed equal increments during its oil
collection mode. Two grab samples were taken from each collection tank before and
after completing each test. Two collection tanks were used for each test, one for
steady state collection and one for beginning and ending transient fluids. A stratified
sample thief was used on each tank after each test to represent 3-in. incremental
layers through the full 86-in tank depth. The analysis combined techniques of known
24
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volumes using graduated cylinder glassware, breaking emulsions with toluene, and
laboratory centrifuges. These percentages of oil and water in known volume history
were used in later calculations using measured fluid flow rates to arrive at oil flow
rates.
Flow rates
Flow rates were measured with various techniques to provide redundancy.
Fresh crude oil distribution rate was measured and calculated with three different
techniques. First, dipstick readings before and afier discharge were divided by a
stopwatch reading. Second, the positive displacement Roper pump revolutions were
multiplied by the displacement volume. Third, the pjmped crude oil passed through a
Tokheim vane-rype totalizer meter that read trial gallons, which were then divided by
a stopwatch reading.
The flow rate of the SOCK collected seawater and skimmed crude oil was to be
measured five different ways. First, a strobosccpe/tachorneter reading of the Tuthiil
rotary positive displacement purnp was taken while counting revolutions timed with a
stopwatch. Next, the flow went through a Nusonics acoustic flow meter where a
voltage reading was compared to a calibrated chart that yielded a flow rate calcu-
lation. Then the flow went through a venturi concentric bell reducer, where the
differential pressure was measured with an ITT Burton indicating switch. The pressure
difference measurement was then used in calculations to arrive at a flow rate. Next,
the flow rate was calculated from before and after dipstick readings in the collection
tanks divided by stopwatch timing of each tank filling. The fifth and last possible flow
rate measurement was liquid level in the collection tanks determined with the
stratified sample thief and a stopwatch timing of each tank filling.
Environment
Environmental measurements included those from the Powhatan's station,
portable station onboard fielded by the Naval Underwater Systems Center, (reference
7) and a group of remote stations. The remote stations were a series of three buoys
deployed in the area, NOAA NYC radio, USCG stations at Ambrose, Sandy Hook,
Manasquan, Barnegat, and Montauk Point, and finally the USN satellite system
(NAVEASTOCEANCEN). Historical data came from the MESA New York Bight Atlas
(reference 10).
One week prior to the ocean dumping, forecasting was begun each day for the
specific area and continued through the test period. The following at sea measure-
ments were taken:
Air and Water temperature,
Wind direction and speed,
Wave height, length estimate, and period,
Near surface current and direction,
Surface water samples in the area, and
Sub-surface water samples downstream at 5-10 m depths.
Measurements were made of the Powhatan's response and position as a portable
test platform during each crude oil dump. These included speed, heading, position,
25
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maximum pitch and roll taken from the bridge instruments. A special portable lab
fielded by the Naval Underwater Systems Center provided an automatic Loran-C
record, video display, and mapping of the vessel's position within the approved dump
envelope (see Figure 5).
The burden of visually estimating the sea state was assigned to ten transient
crew members, most of which had sea duty experience. They were each given a typed
format data folder that portrayed typical and conventional characteristics to observe.
Slick Character
Trained observers evaluated the slick encounter by the skimmer and inter-
actions between the slick generator, the Pcwhstan starboard side water jet slick
control, and the action of the skimmer itself. Eight fansient crew members v.ere
given a typed format data folder in which to record their observations. Some of the
observers had portable audio tape cassette recorders and a radio transceiver. They
were backed up by video and fiirr. records. Each observer was required to specifically
comment on:
Water jet slick control...
genera] appearance and effectiveness.
Oil slick...
general appearance and uniformity,
width and thickness,
gas bubbles and emulsion,
percent entering the skimmer pontoons, and
crisp start and stop of the slick.
Floating platforms, relative movements...
slick generator to Powhatan,
slick generator to skimmer,
Powhatan to slick,
tow rigging to slick generator and skimmer, and
bow wave interactions.
Skimmer...
general appearance and conformity,
motion caused by waves and towing,
oil encounter loss, quantity and location,
oil losses due to headwave, entrainrnent, and drainage.
The quantified thickness was made by taking width estimates from marks on the
skimmer entrance frame and calculating thickness based on the known flow rate and
vessel speed. Several slick thickness guages were considered for the program, but
none appeared either adaptable or proven in the field.
26
-------
^-vc.s.^f-'^ .f -"tr£rj
Li>»*
^|m^%Ii4i^L/j4|
r*
-al- BESaHfcST&vS^4-«^
>' t- * IUJAKK'- ar ^
Figure 5. Auto Loran-C data station.
27
-------
SECTION 5
SPILLED OIL CONTAINMENT KIT
INSTALLATION AND CONSTRAINTS
The Spilled Oil Containment Kit (SOCK) was loaned to the OITC for this
program by Shell Oil Company through their Emergency Response - Oil Environmental
Conservation Operations staff in Houston. Texas. All liaison was through the staff
with support from the Shell Development Company, *'esthollow Research Center,
Houston, Texas. The SOCK was exclusively operated by Shell-trained personnel, two
from Tidewater Contractors, Inc., Amelia, Louisiana and one from the Westhollow
Research Center.
The launching and retrieval required support from three OHM SETT people. The
rigging and installation onboard was a mutually-agreed upon design that was dependent
on the Powhatan's deck equipment and constrained by a rule disallowing welding or
cutting on the vessel's structure or covering deck bits. The need also was to have it
deployed as far forward of the ship propellers as possible which forced the starboard
side installation (Figure 6). The possibility of a port side installation was not
considered because it would require a retrofit. Also, there would be port side
interference from the Powhatan's permanently installed vertical capstan.
One of the outstanding capabilities of the Powhatan is her variable pitch
propellers. The majority of industrial work boats in this class do not have that
versatility or the resulting low speed control capability. Use of a conventional boat
for this program would have required a tug boat to restrict speed or a continuous
clutching in and out of a propeller.
The SOCK hardware available for this program was significantly different from
that described in 1977 (reference 2). The 70,000 ft-lb crane installed forward had been
abandoned and was not part of the current operations. The oil separator compartment
could not be used because the hinged cover and baffle plates were missing. The
number of suction hoses and ports by design were reduced to three 3-in hoses. The
1977 Sock (boom-skimmer component) used a floatation scheme combining air, foam,
and inflated into 42 longitudinal cells and 32 transverse. The 1980 version tested
utilized six transverse and two longitudinal foam cells. The 1977 Sock had a fabric
bottom extending from the forward rigid floating frame back (over halfway) to the
midpoint area. This bottom was conceived to be an advantage in directing fluid flow,
controlling vertical turbulence, and causing the SOCK to act as a skimmer rather than
a splash-over-proof boom. The 19SO version tested did not have a fabric bottom.
The SOCK system arrived at OHMSETT packed on three large tractor-trailers
(two flatbeds and one lowboy). One oversized load required day-time only trucking and
special permits. One trailer contained the main rigid float frame, one transported the
28
-------
'A
-------
SOCK integrated container, and the lowboy was used to transport a tool house with a
separate skid containing the Sock fabric system. The OHM SETT location at the foot
of the Navy pier on the NWS-Earle made it an ideal operations center and staging area
for all equipment in the Research program. A Shell (Westhollow) technician arrived
and utilizing four OHMSETT technicians readied the SOCK for ship installation. Some
refurbishment of the system was required to ready the SOCK after its prior storage
environment. Two 20-ton cranes, a forklift, and various hand tools were utilized in the
assembly and shipboard readiness operations. The assembly area was approximately
10,000 ft2. The work schedule included one 12 and one 6-hour day. The assembly was
straight forward with minimum skill requirements and good supervision. Special color
strips were painted by OHMSETT on the rigid float system for measuring draft and
freeboard oscillations at sea. An overnight rain storm did no: delay the assembly but
did identify a Sock fabric quality problem. Several of the closed fabric cells that
contained the flexible foam floatation were not completely sealed. The next morning
the cells were bulging with rain water. Shell decided to cut water relief holes topside
and in five transverse cells. The deJaminated ceil seams were not repaired arid the
relief holes were left open for the at-sea tests.
The actual installation of the SOCK onto the Powhatan required three iarge
crane lifts and four small crane lifts. A 70-ton crane was required to accomplish the
reach from dock/pier to the vessel deck positions. Dunnage was not used for the
SOCK container, pontoons, and fabric assembly. The loading required a foreman, a
crane operator, and four tag line men. Figures 7 and 8 illustrate the main deck with
the SOCK in place without tie-down rigging, tool house, air tuggers, or strainer in
place. The tie-down rigging was the same OHMSETT design used for all components
on the main deck. It was a modified design that the Navy diving equipment riggers use
for their mission installations on the Powhatan. The SOCK container was secured with
eight tie-down cable units using a combination of thimbles, 5/8-in steel cable, cable
clips, and turnbuckles. Termination points were a standard I.S.O. container shackle to
the container and an eyebolt screwed into the deck. The Sock was atop the container
secured with steel cable and safety chain binders. The two air tuggers were screwed
to special OHMSETT designed swivel mounting plates that in turn were bolted to the
main deck. The SOCK hose manifold/strainer was welded to a steel plate that was
bolted to the main deck. The tool house was secured to the main deck with steel
cable, thimbles, and eyebolts.
PRACTICE AND FINAL CONFIGURATION
The SOCK deployment/retrieval at sea from the Powhatan was thoroughly
planned and practiced before crude oil was dumped. The first practice was from a
small barge in an inland waterway near Morgan City, Louisiana in early March 1980.
Figures 9 and 10 illustrate two views of the SOCK in that launch process. This
practice session was to ensure the SOCK working order after a long storage period and
the deployability of the new SOCK design. The barge deck was ^ ft above water and
the SOCK was 5 ft from the railless starboard edge. The barge was moored in a small
lagoon that had no water current flow that is normally required to unfold the Sock. A
special rigging was used to adjust the Sock axis to the barge. This experiment
concluded that the SOCK was ready for the Powhatan. Several possible launching
problems were anticipated for the at-sea experiments. First the outboard aft D-ring
snatch block cable assembly may snag during deployment. A solution was to grind
down the cable clip to a better taper. The second anticipated problem would be the
30
-------
Figure 7. SOCK, deck view from stern.
31
-------
Figure 8. SOCK, view from bridge deck.
32
-------
j *'-"; -i*': J> JA
" - .-^j-'JcT-^'F SJAr5
Figure 9. SOCK deployment from barge, forward outboard, starboard view.
33
-------
Figure 10. SOCK deployment from barge.
3U
-------
aft Sock fabric bting drawn under the Powhatan's hull. One solution to this was to add
large inflatable spherical floats as a safety contingency. The system arriving at
OHMSETT included two one meter diameter spherical floats. The design intent was
that the floats tethered to the Sock apex would provide a contingency floatation that
would aid in the deployment over the starboard side.
The SOCK hardware and operators were integrated into the USNS Powhatan and
the test program. The following items had significant impact, floor space, and weight
loads:
Containers, 8x35 ft, 32.000 Ib (dry),
Sock fabric/frame, 8x29 ft, 6.500 Ib,
air tuggers (two each), 3x3 ft. 290 !b each,
fluids strainer/manifold, 3x3 ft, 200 Ib, and
tool house, 7x12 ft, 5.000 Ib.
The container includes an integrated diesel hydraulic power plant, valves and
rigid piping, controls, launching rarnps and the positive displacement suction pump.
The fabric/frame, referred to as "Sock" previously, sits on top of the container when
not deployed, therefore its weight is important. The height of the stack is
approximately 19 ft above the deck and it hangs 3 ft over the starboard side. Height
and overhang are important in safely calculating ship stability and docking constraints.
Figure 11 illustrates the deck layout proportions on the main deck of the USNS
Powhatan. The ship's structural frame stations are noted at two foot intervals for
scale. SOCK floor space is designated with thick lines with the test hardware and
ship's hardware in thinner lines.
The SOCK as integrated to the ship required onboard services of air for the
tuggers, water for wash down cleaning, and accommodations for manpower. The
container as previously discussed was latched to the deck. Guy lines for launching
with the air tugger went through fairlead rollers clamped to the Powhatan's starboard
rail. The inboard and outboard Sock tow lines were secured forward to bits on the
foc'sle deck. The Sock launching system was mechanically independent of the ship's
hardware, but required special maneuvers by the ship. The maneuvers were to be
commanded by the SOCK operator to the ship's master. Radio and visual contact is
very important. The ship's speed initially was a slow 0.75 kt with the Sock in the lee
and seas arriving from the stern quarter. Several start/stop and reverse motions are
then required to position the overboard Sock correctly and secure for skimming
operations.
**..
35
-------
(0
.C
5
O
CL
(f)
2
l/)
C
o
o
u
cu
T)
(0
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U
O
0)
s_
3
_D)
il
36
-------
SECTION 6
TEST DESCRIPTION AND PROCEDURES
The most important aspect of the test design was to assume that sea states
would change within small portions of a day. The major emphasis was then to control
other independent variables.
Although each test at sea was different than all of the others, a general pattern
was accomplished on all of the tests TO ensure continuity of procedures. This pattern
was adhered to with consistency allowing for the different types of testing to be
accomplished.
TYPICAL TEST OUTLINE
The general test sequence followed a pattern to ensure all test crew members
and equipment were in concert.
(1) Announce the commencement of test exercise.
(2) Ensure all test crew members are on station.
(3) Bring Powhatan to approximate test speed and correct heading relative
to sea heading.
(ty) Remind test crew of procedure with times, quantities, and rates.
(5) Answer any questions from test crew.
(6) Check Powhatan speed using wood chip and adjust as necessary.
(7) Establish announced distribution rate through recirculation loop.
(8) Record tank soundings of distribution and collection for pre-test
volumes.
(9) Begin distribution of crude oil.
(10) Announce the exact time that oil distribution began.
(11) Start Tuthill pump after the established preload period.
(12) Adjust Tuthill pump rpm to four-thirds desired pump rate.
(13) Pump into initial slop tank until oil appears at discrete sampling point.
37
-------
(14) Switch pumping frc>:r. the initial siop tank to designated steady state
tank.
(15) Stop oil distribution.
(16) Switch Tuthill pump discharge to secondary slop tank after designated
steady state period.
(17) Continue pumping until discrete sampling point consistently shows
mostly water.
(IS) Stop Tu-tnill pump.
(19) End-of-test time ar,r!our>cfcrr.ini. Allow settling time in collection tanks.
(20) Record tank soundings of the distribution tanks after distribution.
(21) Record recovery tank soundings for total fluid.
(22) Decant recovery tanks.
(23) Record tank soundings on decanted volume.
(24) Take grab samples using marked 200-ml bottles of recovered oil-water
emulsion.
(25) Send samples to onboard laboratory for analysis.
A time line analysis is shown below for a hypothetical test. Figure 12, a view
from the aft end, illustrates collection tank positions. Note large Roman numerals on
each tank. There were minor exceptions to the procedures that were noted for each
test. Redundancy was built in to offer a choice of flow rate measurements using the
acoustic flow meter and venturi, and total quantity measurements using the stratified
sampling technique. The day-to-day and test-to-test procedure and data collection are
summarized below along with time line summaries for each test and day:
(1) Confirm Powhatan's relative surface velocity using wood chip method.
(2) Establish desired distribution rate through the oil recirculation loop.
»
(3) Initiate oil distribution through the oil slick generator.
(4) Start Tuthill pump after preload period as defined by designated volume
and theoretical distribution rate.
(5) Route skimmer discharge to slop tank until oil is observed at the discrete
sampling point.
(6) Route discharge to steady state tank.
(7) Stop oil distribution.
38
-------
<. ?.J*
v \ 5. ?.
f.~*r
Figure 12. Collection tanks I, II, III, and IV (partially hidden)
39
-------
(S) Redirect discharge to slop tank lor remainder of test.
(9) Stop TuthilJ pump.
DAY-TO-DAY SUMMARIES
A summary of each day's activities in regard to specific tests should relate
exceptions and portray a few logistics decisions.
8 April 1980. Sandy Hook Bay
At 1300 hours, the Powhatan is fully loaded with test equipment and the SOCK.
Carrying no crude oil, she leaves NVi'S-Earle for trial runs in Sandy Hook Bay to
acquaint the test crew with the deployment/retrieval sequence of both the Sock and
the slick generator.
At 1400 hours, the Sock is successfully deployed and tow line length adjust-
ments are made for the best sea keeping arrangement necessary for integration with
the Powhatan.
At 1600 hours, the slick generator is lowered to the water surface using the
ship-board crane and operator. At 1730 hours both the Sock and the slick generator
are brought back aboard and the Powhatan heads to port. The tarpaulin oil delivery
ramp on the slick generator needs to be weighted to make it less sensitive to the wind
in oil distribution process.
9 April 1980, New York Bight
At 0232 hours, the Powhatan leaves NWS Earle for the test site carrying 18.93
m3 (10,000 gal) of La Rosa crude oil. At 1000 hours recirculation pumping begins to
certify the hose connections and correlate the tank soundings to the in line positive
displacement meter readings.
At 1100 hours Sock deployment procedures are activated in heavier sea state
than encountered in the bay area. A hydraulic fitting is broken during deployment so
the Sock is recovered and the fitting is replaced.
At 1300 hours, the Sock is redeployed. High winds speed of 20 kt with 24 kt
gusts made the crane operation dangerous and prevented the deployment of the slick
generator.
Since the black crude oil cannot be dyed to improve photographic resolution, at
1410 hours a small sample of the La Rosa crude oil (600 ml) was poured over the side
of the vessel for visual sighting practice. This dump was considered essential to the
program for qualitative data later and so was characterized as test number one.
The Sock was brought back aboard at 1500 hours for cleanup and transportation
to Earle.
-------
10 April 1980, New York Bight
Heavy fog and seas throughout the day prevented the safe deployment of the
Sock. The visibility limitation was considered to cause a test control problem and thus
cancellation of the deployment was prudent engineering practice.
11 April 1980, New York Bight
Having remained at sea due to fog on 10 April, the Powhatan is still fully loaded
with 37.85 m^ (10.000 gal) La Rosa crude oil onboard.
At 050C hours the Sock is deployed over the starboard side of the Powbstan and
the slick generator is lowered directly in front of the Sock mouth. The slick generator
is maneuvered to the designated operating position using forward tow lines and aft tag
lines and secured. The tarpaulin has been weighted with 8-rnm (5/16-inch) steel chain
for ballast. The water jets are turned on using the Powhatan fire fighting system as a
supply source.
Test Two
At 0930 hours the preparation for the first large-scale, at-sea testing with oil is
begun. The test is designed to verify the phenomenology of the Sock to contain oil
prior to offloading. The test is actually a test which treats the Sock as a boom to
contain an oil slick.
The Powhatan is brought to speed and verified to be at 1 kt using the
flourescent yellow-orange wood chip method.
Oil distribution rate is set at 74.9 m3/hr (300 gpm) and at 0938 hours all
stations report ready. The slick generator deposits 1.89 m^ (500 gal) of oil on the
wrater surface over 103 seconds.
Visual observations from the bridge, fantail, starboard side, and the MonArk
concur that approximately 80% of distributed oil reaches the skimmer mouth. The
remaining 20% missing the mouth is approximately half inboard and half outboard of
the mouth.
After visual observations were made and photographic and video tape records
were taken, the oil remaining in the Sock was pumped into collection tank number III
to confirm that the oil collection system functioned properly and, more importantly,
to minimize the oil left at sea. It was at this point that both the acoustic flow meter
and the bell reducing venturi were found to produce erroneous data or not functioning,
eliminating two of the redundant means of collected fluid measurements.
Skimmer rating criteria are not given for the second test. The test was not
designed to test the complete skimmer package. Only the oil keeping ability was
effectively tested. Evidence of drainage, entrainment, and other loss mechanisms
were monitored.
The event time line for test two is shown as follows:
-------
(1) Start pre-test procecj-es.
(2) Speed check, confirm 1 kt.
(3) Start recirculation mode for oil distribution.
(4) Begin oii distribution rate at 68 m^/hr.
(5) Water quality sample.
(6) Stop ciJ distribution, at 1.89 m^.
(7) Observation of Joss mechanism. vi?jal observation of slick generator
performance.
(8) Start Sock pump and collect oii.
(9) Stop collection.
(10) Stratified sample analysis.
(11) End of test.
(12) Determination of skimmer loss.
Test Three
At 1153 hours the third test was run very similarly to the second test. The Sock
was used again as a boom. The test was run to determine the speed of gross failure
due to entrainrnent of the captured oil.
Test three began with a wind-driven sea surface relative to Sock velocity of 1
kt and progressed to 2 kt with &-kt increments.
The Sock was pumped out after the test to quantify the skimmer loss during this
exercise and to clear the remaining oil prior to the next test. The time line notes
visual observations of the test at the various speeds tested and is shown below. Again,
skimmer rating criteria for the SOCK are not given since the skimmer was used as a
boom rather than as a skimmer.
(1) Establish surface velocity at 1 kt.*
(2) Set oil distribution rate at 3^ m^/hr (150 gpm).
(3) Begin oil distribution.
(*f) Losses formed at rear are indistinguishable from oil that misses the
rnouth of the Sock.
(5) Increase speed to 1.5 kt.
-------
(6) Oil that has accumulated on SDCK fabric begins to wash off, mixing with
skimmer loss.
(7) Decrease speed to 1 kt.
(8) Oil distribution complete.
(9) Estimated loss rate through the skimmer, 2 m^/hr (15 gpm).
(10) As oil from slick generator clears, a more defined loss mechanism is
apparent at 1.5 m^/hr (10 gpm). Skimmer loss forms a solid slick 0.5-0.7
rn (5-10 ft) wide and 2-^ mm thick. The slick is black, emulsified oil.
(11) Increase speed to 1.5 kt.
(12) Vortices appear behind skimmer apex. Slick losses continue and form
droplets. The loss seems to originate at inboard side in front of solid
floatation chambers.
(13) The Sock skirt billows out, belching oil at random time intervals
concurrent with wave crests.
(14) Speed increased to 2 kt.
(15) Sock forms massive turbulence centering behind the apex. The quantity
of oil lost is noticably decreased. The decrease is caused by less oil
depth in the Sock and because the oil is resurfacing downstream out of
view.
(16) Decrease speed to J4 kt. The slick once again forms as a thick, solid
mass behind the apex.
(17) End of test.
Test Four
The first test of the skimmer performing in its dynamic operation, the surface
curent relative velocity was set at 1 kt and oil distribution was established at 68 ^/hr
(300 gpm). At 1503 hours, oil distribution began and lasted 665 seconds. The Sock was
charged with a 1.89 m^ (500 gal) preload prior to starting the Tuthill offloading pump.
The total distribution of 12.5 m^ (3,300 gal) was fed into the mouth of the Sock with
100% actually entering the SOCK.
Confusion and differing opinions of SOCK operators as to the established test
procedure on the dynamic testing of the SOCK lead to the execution of a test that did
not follow the standard procedure that had been outlined. The actual procedure
followed is summarized as follows:
(1) Confirm Powhatan speed at 1 kt.
(2) Establish recirculation rate of 68 m3/hr (300 gpm).
43
-------
(3) Begin oil distribution.
"*» (ft) Preload distributed, Tuthill pump started, at oil switch to recovery tank
I.
(5) Stop oil distribution.
(6) Stop pumping into tank II, begin pumping into tank III which has been
designated as slop.
(7) Tuthill purnp rate slowed.
(8) No pumping, Tuthili stopped.
(9) Switch to tank IV.
(10) Various pumping rates.
(11) Stop test.
During tests conducted on 11 April 1980, 16.25 m3 (4,291 gal) of oil was
distributed to the Sock 13.9 m3 (3,667 gal) of which was recovered. The Powhatan left
the operations area at 1748 hours and docked at the NWS Earle pier at 2146 hours.
12 April 1980, New York Bight
The Powhatan departs NWS Earle at 0130 hours carrying 37.85 m3 (10,000 gal)
of La Rosa crude oil. The recovered fluid from 11 April has been offloaded and
transferred to land-based storage. The Powhatan arrived in the area designated by the
Research Permit at 0538 hours.
Test Five
The Sock was deployed at 0700 hours in preparation for the third day of actual
testing. The oil slick generator was successfully placed in front of the mouth of the
Sock employing the onboard crane. The Powhatan speed is adjusted to be 1.4 kt and
the oil distribution is set at 46.6 m3/hr (200 gpm). The oil is distributed on the water
surface at 1032 hours. A total of 9.31 m3 (2,400 gal) is distributed over 720 seconds
with 100% of distributed oil reaching the Sock mouth.
The SOCK recovers a 3.79 m3 (1,000 gal) preload, requiring a 330-second wait
between the start of oil distribution and the starting of the Tuthill pump at 270 rpm
with steady state beginning at the first oil in the discrete sampling port.
Oil was present in the discrete sample port 35 seconds after the Tuthill is
started. The steady state period begins for 360 seconds with collection routed into
tank IV for an additional 600 seconds. The time line for test five is given as follows:
(1) Speed check at 1.4 kt.
(2) Establish 46.6 m3/hr (200 gpm) flow for distribution.
w
44
-------
(3) Oil distribution begins.
(4) Tuthill pump starts.
(5) Oil observed at discrete sample point.
(6) Switch to recovery tank.
(7) Oil distribution complete.
(8) End of steady state recovery. SOCK discharge switched to collection
lank IV.
(9) End of test, Tuthili pump stopped.
Test Six
The oil distribution rate '«as set at 68 m-'/hr (300 gpm) and the Powhatan speed
was slowed to 1.3 kt. Oil distribution was begun at 1516 hours lasting 585 seconds, the
first 230 seconds of which is dedicated to preloading.
The preload period was spent before starting the Tuthill recovery pump which
was running at 400 rpm (maximum). Oil is observed at the discrete sampling point 60
seconds after the collection begins. Steady state collection begins at this point and
continues for 300 seconds when the discharge is routed to tanks for the remaining 600
seconds, if necessary. The time sequence is summarized as follows:
(1) Adjust Powhatan speed and establish oil rate in recirculation mode.
(2) Begin 68 m3/hr (300 gpm) distribution.
(3) Start Tuthill pump.
(4) Oil observed at discrete sampling point and discharged in steady state
recovery tank.
(5) Terminate oil distribution.
(6) End steady state period route discharge to slop tanks.
(7) End of test, stop Tuthill pump.
During this test, oil was apparent at the trailing edge of the Sock causing a
slick roughly the width of the SOCK and tapering to a sheen 7 m (21 ft) behind the
apex of the Sock. The waves during this test were determined to have a one-third
significant wave height of 1.4 m cresting every 3.7 seconds (Reference 7).
After measurements are recorded for tank soundings and general topside
cleanup is done, the Powhatan leaves the operations area at 1638 hours for docking at
NWS-Earle at 2018 hours.
45
-------
On 12 April 19SG, 19.9 m3 (5,261 gal) of La Rosa crude oil was distributed on
the water surface daring test five and test six, of which 17.3 m3 was recovered.
v..
13 April 1980, New York Bight
Leaving early, fully loaded with 37.9 m3 (10,000 gal) of crude oil for testing,
the Powhatan departs NWS-Earle for the assigned operations area. The Powhatan
arrives on station at 0750 hours prepared for the day's testing.
Test Seven
The SOCK is not launched until 1000 hours. The oil slick generator is
overboard, the Powhatan speed is confirmed at two kt, and the oil is ready to be
distributed at ^1.9 m^/hr (100 opm) by 1115 hours with the oil first being distributed at
1138 hours. A total of 7.84 rrH (2,100 gal) was distributed over a testing time of 1230
seconds.
The SOCK received a preload of 3.75 m^ (1.000 gal) during the first 593 seconds
of the test. The Tuthill collection pump was started 630 seconds into the test allowing
for a 37 second transient time. At 5'40 seconds, the vessel speed was decreased from
two to 1.8 kt. A time lag of 90 seconds was encountered before oil appeared at the
discrete sample after the pump was started and the SOCK discharge was routed to the
steady state collection tank for 600 seconds. All the remaining fluid was pumped to
the slop tank for an additional 660 seconds. The time line analysis is given as follows:
(1) Bring speed of Powhatan to 2.0 kt and establish a distribution flow of
41.9 m^/hr (100 gpm).
(2) Start oil distribution.
(3) Bring speed of Powhatan to 1.8 kt.
(4) End preload period.
(5) Start Tuthill pump.
(6) Oil detected at discrete sample point, discharge switched from slop to
steady state tank.
(7) Stop oil distribution.
»
(8) End of steady state collection.
(9) End of test, pump stopped.
Test Eight
The second test of 13 April 1980 began at 1H8 hours after establishing the
distribution rate of 29.5 m^/hr (130 gpm) and the relative surface velocity of 2.1 kt.
The oil is distributed for 765 seconds.
46
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The preload period of ^80 seconds was distributed before the Tuthill pump was
started. Once pumping begins, it required 245 seconds for oil to be observable at the
discrete sample port. At this time the fluid is transferred from slop tanks to the
steady state collection tank for 300 seconds and to the siop tanks for the final 600
seconds. The time line analysis is shown as follows:
(1) Establish rate of 29.5 m^/hr (130 gpm) at oil distribution with Powhatan
at 2.1 kt.
(2) Start distribution.
(3) End of preload and Tuth.il] started.
(4) Oil observed, skimmer output routed TO steady state tank.
(5) End of oil distribution.
(6) Suction discharge to sjop tank, end of steady state.
(7) End of test, Tuthill pump shut off.
-------
SECTION 7
DATA COLLECTION
The data were taken at 23 separate locations scattered over the main deck and
bridge house of the Powhatan, including the rennote buoy for wave analysis. The
information to be recorded, the means of measurement, and the units in which the
measurement is recorded are tabulated for easy reference in Table 4.
The weather was monitored for one week prior to the first day of testing. The
L'SCG and the National Weather Service recorded data daily in sheets shown in Figure
13. The National \Veather Service was monitored from the continuous broadcast at
162.55 MHz from New York City. The USCG was contacted at four locations
(Montauk Point, Ambrose Light Tower, Sandy Hook, and Manasquan Inlet) daily to
obtain actual weather information at that time. All other data were recorded at sea.
TABLE H. RECORDED DATA
General
Category
Specific
Information
Means of
Measurement
Units of
Measurements
Environmental,
Weather
Environmental,
Waves
Skimmer Speed
Dry bulb air
temperature
Wet bulb air
temperature
Wind direction
Wind speed
Wave height
Sheltered °F
alcohol thermometer
Sheltered, wicked °F
alcohol thermometer
vane degrees
anemometer knots
buoy
Wind driven current (Wood chips/timer)
(Continued)
feet
^seconds
seconds
-------
TABLE tt. (CONTINUED).
General
Category
Specific
Information
Means of
Measurement
Units of
Measurements
Oil Distribution
Oil Recovery
Oil temperature Bimetal
thermometer
Initial tank height Dipstick
Final tank height Dipstick
Water jet pressure In-line gauge
Distribution time Stopwatch
Distribution volume Positive dis-
placement meter
op
inches
inches
psig
seconds
gallons
Prior to test tank Dipstick
height
Tuthill speed
Stroboscopic
Jn-line gauge
inches
rpm
Vessel Statistics
Controllable
Vessel speed
Direction
Longitude
Latitude
Doppler meter
Powhatan bridge
Magnetic compass
Powhatan bridge
Loran-C
Loran-C
knots
degrees
degrees, minutes
degrees, minutes
(Continued)
-------
TABLE it. (CONTINUED).
Genera]
Category
Vessel Statistics,
Uncontrollable
Specific
information
Means of
Measurement
Units of
Measurements
Pitch
Roll
Bridge bubble
pitch indicator
Bridge bubble
roll indicator
Pitch (roll) period Timing of three
pitches (rolls) and
Oil Collection
Volume of
collection
Decanted volume
Emulsion quality
Dipstick
measurement
Dipstick
Grab sample
Oil Collection, Discrete
Emulsion quality
Relative time
Discrete sample
Stopwatch
degrees
degrees
seconds
inches
inches
percent oil
percent oil
seconds
The following secondary measurements were planned but equipment failure prevented
data acquisition:
Oil Distribution
Oil Collection
Oil Collection
Rate
Rate
Rate
Hydraulic Pump, rpm
Acoustic Flowmeter
Venturi
Voltage
Voltage
Differential
pressure, inches
of water
50
-------
D ATE
GENERAL CONDITIONS
TIME OF DAY
JPRE DICT I ONS
MONTAUK
POINT
AMBROSE
LIGHT
TOWER
ENE
SANDY HOOK
AIR TEMP.
OF.
SEA T E M R_ G£_
WAVE H T. £1_
PERIOD ..__ _ S_e_c.
BAROMETRIC
PRESSURE lD._H_o_
V I S I B ! L I T Y n_ML
AIR TEMP.
SEA TEMP,
WAVE H T.
PERIOD .
ESE BAROMETRIC
rSE PRESSURE
VI SI Bl LI T Y
AIR T E M P
SEA TEMP_
WAVE HT.
PERIOD
ESE BAROMETRIC
PR E S S U R E
VI SI Bl L I T Y_
MANASQUAN
INLET
NN
NE
AIR T E M P._
SEA TEMP.
WAVE H T.
PERIOD
B AROMET Rl C
PRESSU RE
SSW
Figure 13
VISIBILITY
Daily weather record sheet.
51
_ELU
JLfi-C,.
In Hg
n. Mi.
Ft
Sec.
_liLJ±g^
n. Mi-
_£i^_
_-S_ec_._
n Hg.
ru_M_L_
-------
SECTION 8
LABORATORY ANALYSIS AND SAMPLING PLAN
OCEAN WATER SAMPLING AND ANALYSIS
Grab samples of ocean water in the test zone were taken during the test
program. These samples were analyzed for temperature, salinity, and conductivity
using a Yellow Springs Instruments, Model 33 SCT Meier, pH \vas determined by a
Fisher Scientific Model 120 pK meter, and specific gravity by a hydrometer.
Ocean Water - Summary of Properties
Salinity 32.5 ppt
Conductivity 43,500 umhos
Temperature 6.7°C
pH 7.4
Specific Gravity 1.021
Water properties obtained are shown below. Selected samples were analyzed for crude
oil content. Analysis results are shown in Table 5, (Reference 3).
TABLE 5. OCEAN WATER SAMPLE ANALYSIS
Date
9 April 80
10 April 80
1 1 April 80
12 April 80
13 April 80
12 April 80
12 April 80
13 April 80
13 April 80
Sample
Description
Ocean
Ocean
Ocean
Ocean
Ocean
Recovery Tank Draining Test //5 - Tank II
Recovery Tank Draining Test #5 - Tank II
Recovery Tank Draining Test #6 - Tank IV
Recovery Tank Draining Test #6 - Tank IV
Oil
Content
ppm
45ND*
25ND*
25ND*
25ND*
25ND*
80
70
200
235
*ND = content less than Jimit of detection
TEST OIL PROPERTIES SAMPLING AND ANALYSIS
Grab samples of the La Rosa crude were taken from the distribution tanks.
Analysis results for a viscosity versus temperature curve were obtained using a
Brookfieid Model LVT viscometer at about 22°C and a Fisher/Tag Saybolt Viscometer
***,..
52
-------
Figure 14. Centrifuge for oil/water analysis in Powhatan lab.
53
-------
Figure 15. Discrete sampling station.
-------
SOCK discharge pipe
Sample pipe
*
Holes for sample collection
Sample
bottle
Flow in SOCK discharge pipe impacts holes in sampling pipe. Discharge
pipe is full at all times and well mixed.
Figure 16. Diagram of discrete sampling pipe.
55
-------
at about 75°C. Viscomeier results \vere converted to centistokes (cSt) using
procedures in ASTM STP 43C and plotted using ASTM D341 viscosity versus temper-
ature charts. Oil viscosity at ocean temperature was then read from the chart. Oil
surface tension (SFT) and interfaclal tension with ocean water (1FT) were found using a
Fisher Scientific Model Surface Tensiomat at a room temperature of 18 +2°C. Water
content of the crude was found by centrifuging with toluene using ASTM method
D 1796-75. Specific gravity was determined using a hydrometer. Oil properties
obtained are shown below:
Lc Rosa Crude -_S_u_rnrnary of Proper ti_es
Specific gravity 0.916
Surface tension 34.8 dynes/cm (e 18°C
interfacial tension 27.7 dynes/cm (d 1S°C
Viscosity 146 cS't (c 0°C
Viscosity 9.7 cSt (d 100°C
Flash Point 54.5°C
SKIMMER RECOVERY SAMPLING AND ANALYSIS
Fluid recovered by the SOCK was sampled using two methods. Discrete
samples were taken from the recovery piping near the exit of the SOCK pump every
minute and composite samples were taken from the storage tanks after each test.
Samples were analyzed by centrifuge using ASTM D1796-75 to obtain oil and water
percentages (see Figure 14). Analysis of the discrete samples provided the recovery
efficiency (RE) for every minute of pumping time. Analysis of composite samples
provided the percentage of oil in total fluid recovered. Total oil volume recovered
(Vro) was then calculated using tank soundings and:
Vro equals (Volume total fluid emulsion in tank) multiplied by
(percent oil in tank)
Throughput efficiency (TE) could then be calculated using Vro the volume of oil
distributed (V) and:
TE= (Vro/Vdo)*100
Discrete samples were collected using a sample tap previously installed in the
recovery piping near the SOCK pump exit (Figure 15). Sample tap geometry is shown
in Figure 16. A 1 mm x 61 mm polyethylene tube was attached to the top for filling
200 crr)3 sample bottles. Typically, each sample bottle filled in less than 10 seconds.
Since samples were taken at 60 second intervals, the flow was allowed to run
continuously and diverted to a separate container for the period between samples.
Composite samples were taken from 18.9 m^ tanks holding the fluid recovered
by the SOCK. One tank contained pre and post-steady state (slop) recovery and
another contained fluid recovered during steady state. Fluid levels in the tanks were
measured after each test using a dipstick and ruler (Figure 17). Samples were then
taken using the Johnson Sampler (Figure 18) for oil and water analysis. Each segment
of the Johnson Sampler was analyzed separately, with oil percentage reported. Total
volumes recovered in the slop and steady state tanks were found by comparing fluid
SB
-------
'.J>"5.'«''
*- **. 4
_ .-,*r-
JiZ-*. ;J"A*-.5:i...i~"i3felSj£i»S. '
Figure 17. Dipstick sampling station.
-------
Figure 18. Johnson stratified sampling on station
58
-------
height in the tanks to a calibration curve of tank volume versus height. Oil voiurr.es
recovered in the slop and steady state tanks were calculated using the oil percentages
found for each segment of the Johnson Sampler. Tank volume represented by each
segment was multiplied by the percent oil found in the sample of that segment. Oil
volumes for each segment were then added to give the total oil volume in the tank.
Results of a hypothetical example are shown in Table 6.
TABLE 6. EXAMPLE RESULTS.
1
s
Si
ohnson
ampler
egment
1
2
3
4
5
6
7
8
9
10
iota!
volume
per 0.3-m
segment, m^
.50
.75
1.10
1.55
2.20
3.00
4.00
5.20
6.70
8.50
Slop tank
sample
oil,
%
5
10
15
20
25
30
35
^0
h 5
50
Slop tank
oil
vojume
per segment,
0.025
0.075
0.165
0.31
0.55
0.9
1 .4
2.08
3.015
4.25
Steadv
state
sarr.pje
°'^
10
20
30
40
50
60
70
80
90
100
Steady State
oil volume
per segment,
0.05
0.15
0.33
0.62
1.1
1.8
2.8
4.16
6.03
8.5
Total oil recovered 12.77 m3 25.54
Each tank was allowed to settle as long as practical before free water was
drained. Tank fluid levels were again measured and samples taken with the Johnson
Sampler for oil and water content analysis. Total fluid after draining and oil volumes
were obtained using the calculations of the previous example. Water drained prior to
sampling was added back to the total fluid after draining result to obtain total fluid
recovered. Results obtained from the before and after draining samples were
compared to determine error in the measurements.
One problem surfaced during sample collection using the Johnson Sampler. Oil
in the sample would adhere to the sampler, requiring a toluene wash to remove the oil
to a sample bottle. Unfortunately, the polycarbonate sheath was attacked and
destroyed by the toluene left on the sampler. Since the entire stock of samplers was
used by the middle of Test 4, an. alternate method was then employed to sample the
recovery tanks. Tank levels were measured after each test, then drained of free water
and measured again. Comparison of the two tank levels gave the amount of water
drained. An open 125 ml sample bottle was taped to a steel rod and slowly lowered
from the liquid surface to the bottom of the tank and back to the surface (Figure 19).
Since fluid flowed into the bottle during the entire period, the sample was assumed to
represent the contents of the tank. Some error is expected as the tanks are horizontal
cylinders so one level does not contain as much fluid as another and the tank may not
be well mixed so water and oil pockets may be present.
59
-------
Lab Analysis of the sample provided the oil percentage in the fJuid left in each
tank. OiJ volumes recovered and throughput efficiency M'ere calculated same as for
Clohnson samples taken from drained tanks.
Figure 19. Grab sampling station.
60
-------
SECTION 9
DATA REDUCTION
Preliminary reduction of data onboard the Prwhatan was necessary to maintain
control of testing and evaluate results to determine the need, if any, to altar the
preliminary test matrix. This preliminary data reduction was for purposes of on-scene
evaluation only and was never intended to give the final results which required many
man-hours in an environment more conducive to the detailed calculations necessary
for the total reduction and evaluation of the data package.
SHIPBOARD REDUCTION
Certain data was transformed with pretest known quantities to produce a
calculable quantity for decision making onboard. The wind-driven surface velocity was
an important test parameter. The speed was computed by measuring the time
necessary for the wood chip to travel a set distance 30.5 m (100 ft). The time was not
the desired quantity, the speed in kt must be determined. Similarly the tank soundings
provide the heights of fluids in the tanks but the desired quantity was the volume in
the tanks at the time of sounding so that preliminary values for recovery and
throughput efficiency, and quantification of skimmer loss could be computed onboard.
FINAL REDUCTIONS
Although the shipboard calculations for skimmer rating criteria were done on a
test-to-test basis, the final reduction on land was done on a grouped basis. The data
naturally falls into four categories: Environmental, Distribution, Collection, and
Other.
Environmental
The environmental data was correlated to the vessel speed, heading, position,
time, and test number. The actual reduction was done by the USN-NUSC laboratory
representatives (Reference 7). Figure 20 shows the buoy deployed. Figure 21 is a
sketch of the major components of the buoy.
Distribution
The quantity of oil distributed to the mouth of the Sock was measured using a
152 rnm (6 in) positive displacement (PD) meter placed in the distribution line and
sounding of the crude oil storage tank designated for use in this specific test before
and after the test (tanks V and VI were designated as crude oil storage tanks). A third
measurement of the distributed volume was to have been based on the theoretical
crude oil pump rate determined by the rpm of the hydraulic power pump, but the
61
-------
.:~:385£*Sg:Y""
Figure 20. Wavetrack buoy at sea.
62
-------
Beacon
Electronics
Housing Sphere
Accelerometer
Housing
Mooring Attachment
Figure 21. The ENDECO wavetrack buoy.
Note: This system includes a fiberglas buoy, double integrator,
batteries, and FM transmitter.
63
-------
tachometer did not function prc.perly. The time for oil disfibution was recorded in
seconds as the time from when the valve to the oil slick generator was opened until
the same butterfly valve was closed. The distributed volume to time ratio gives
redundant rates based on tank soundings and the inline meter.
Since the preload volume had been designated rather than the preload time, the
preload times are calculated based on the given preload volume and the three
distribution rates (tank soundings, metered, and averaged).
The difference between the total distribution time and each of the redundant
distribution times can produce the steady state time based on the distribution volumes.
A summary of the reduced distribution data is given in Table 7.
Recovery
Data reduction for the recovered fluids is similar to the tank soundings of the
distribution calculations. Each recovery rank was sounded three times. The pre-
colJection height, total collection height, and decanted height are recorded for each
collection tank. Each of these heights is translated into the appropriate volumes using
linear interpolation of the computer generated numerical integration tables for the
height-volume relationships. The volume of the total collection height less the volume
of the pretest sounding is the total collected volume. The decanted volume less the
initial volume is the total collected volume of the oil-water emulsion. It is a sample
of this volume that is given to the onboard laboratory for analysis.
There is a choice as to how this data can be treated to calculate the volume of
oil collected based on differing starting assumptions. The first method assumes that
all of the initial volume is pure crude oil. If this is true, then the volume of recovered
oil is given by:
V equals (Volume of recovered emulsion) multiplied by
(percent oil in tank) minus (initial tank oil volume)
The second method bases itself on the La Rosa crude oil being exposed to sufficient
water and mixing energy to form a saturated, stable, tight emulsion in all cases. The
initial (pre-test) volume is then assumed to have essentially the same relative oil
content as the overall emulsion. With this assumption, the recovered oil volume
becomes:
V = (Decanted oil volume) minus (initial tank oil volume)
multiplied by (percent oil in tank)
This assumption yields higher performance values in all cases and became the
operational assumption for the recovered fluid data reduction.
These calculations were compiled for the steady state recovery tank(s) and the
slop tank(s) for each test run. The results are given in Table 8.
A second steady state period was defined to be the total Tuthill pump time
equal to the total distribution time.
-------
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Skimmer Rating Parameters
Calculation of the skimmer rating parameters is readily accomplished using the
standard OHMSETT working equations for Oil Recovery Rate, Throughput and
Recovery Efficiency outlined in the OHMSETT Standard Operating Procedures (SOP's).
TABLE 8. SUMMARY OF RECOVERED FLUID
Test
no.
1
2*
3*
14*
5*
6
7
8
Tank
no.
Designation
Heights (cm)
initial full decant
No recovery
HI
IV
II
I
III
IV
III
IV
I
II
III
IV
I
II
Steady State
Slop
Only
Steady State
Slop
Slop
Steady State
Slop
Steady State
Slop
Steady State
Slop
Steady State
Slop
0
0
0
0
19.1
43.2
11.4
8.9
11.*
7.6
8.3
9.5
8.9
9.5
19.1
43.2
7.6
100.3
116.8
101.6
55.9
85.1
78.7
119.4
50.8
58.4
35.6
40.6
19.1
43.2
7.6
100.3
116.8
101.6
55.9
73.0
63.5
114.3
48.3
50.8
22.9
22.9
initial
Volume
full
(m3)
decant
j\o recovery
0
0
0
0
0.9
3.1
1.7
0.3
1.7
0.2
0.3
0.3
0.3
0.3
1.0
3.1
0.2
9.9
12.0
10.1
4.5
8.0
7.2
12.3
4.1
5.0
2.3
2.8
1.0
3.1
0.2
9.9
12.0
10.1
4.5
6.5
5.3
11.7
3.6
4.1
1.2
1.2
*The stratified sample technique was used in tests 2, 3, 4 and the steady state tank for
test 5. Tank soundings were recorded on the nearest 0.64 cm mark and converted to
gallons.
The Oil Recovery Rate (ORR) is a measure of the SOCK's ability to remove oil
from the environment (water surface) to the o'nboard recovery tanks and is computed
by the equation:
ORR = (Volume of oil collected) divided by (Time for that collection)
The Recovery Efficiency (RE) is the ratio of oil collected divided by the total
fluids, oil and water, collected. The throughput efficiency (TE) is a measure of the
quantity of oil available for recovery to that which is actually recovered. The
66
-------
available oil is thai within the sweep width of the skimmer entrance. The operating
equation is:
TE = (Volume of oil recovered) multiplied by (100)
(oil distributed multiplied by (percent encountered)}"
Because of the preloading, the oil distributed is not related to all steady state
conditions and the substitution of oil distributed = Q~ t into the TE working equation
yields: D ss
TE = Vrc xlOO
QDtsSE%
where Qrj is the distribution rate for the corresponding time interval defined as steady
state, tss, and E% is the percentage oil encountered.
These dynamic equations are then applied to the various possibilities presented
by the complete data package. This application yields for each test 18 possible values
for TE, and two values for the RE and ORR. The combinations are illustrated in Table
9.
TABLE 9A. THROUGHPUT EFFICIENCY COMBINATIONS.
Tank
Soundings
Throughput Efficiency
Tank
Sounding TEj
Metered
Output TEtj
Average TE7
Tank
Sounding TEjo
Metered
Output TE13
Average TE]g
Metered
Output Average
TE2 TE3
TE5 TE6
TEg TE9
TE11 TEl2
TEj^ " ^^15
TE17 TE18
through TEg - Steady State #1
TEjo through TE]g - Steady State #2 (Extended Steady State)
67
-------
TABLE *&. OIL RECOVERY RATE.
Oil Recovery Rate
Tank Soundings for Oil Volume
Steady State ORRj
Extended Steady State ORR2
TABLE 9C. RECOVERY EFFICIENCY.
Recovery Efficiency
Tank Soundings for Oil Volume
Steady State REj
Extended Steady State RE2
The reader is cautioned on comparing columns and rows, and to understand that
this program was designed with redundant measuring techniques, not to be confused
with duplicates as in establishing statistical confidence. The additional values for TE
are, of course, generated by redundant distribution measurements. If all instruments
had functioned property, the matrices for the RE and ORR would have been expanded
similarly.
The rating criteria is now broken into steady state and extended steady state
for comparison. The ORR and RE is straight forward, but the TE requires comparison.
Fortunately, the differences between the TE values is generally small enough to be
accounted for by error in accuracy and precision of the data taken. If this had not
been the case, an analysis of the measurements taken and the means of measurement,
and probable error would be necessary to eliminate the data that was inconsistent with
other reading and measurements.
Other
Weather data, vessel heading, pitch and roll of the Powhatan and dump location
did not need to be reduced, only correlated by test number, time and date. Skimmer
losses were conservatively estimated at sea allowing a large enough safety factor for
the simplified shipboard assumptions and to ensure confidence that the test program
remained within the EPA dumping permit for total at-sea losses. These skimmer
losses were recalculated without the simplifying assumptions for daily reporting to the
68
-------
US EPA (Region II) and USCG Captain of the Port (3rd District). The total skin.rner
loss was determined to be 17.8 m3 (4.700 gal) and the maximum allowable loss was
'
-------
Time for total d::-:rib!jtior; (i) - 720 s = 0.20 hr
Distribution Rate
Based on Positive Displacement
QPD = 9.31/0.20 = 46.55 m3/hr
Based on Tank Soundings
QTS = 10.40/0.20 = 52.00 m3/hr
Average = (46.55 + 52.00)/2 = 49.28
Preload Size, V = 1.S9 m3
Preload Time
Based on Positive Displacement Meter
TPL,PD = 1.89/46.55 = 0.04 hr = 146.3 s.
Based on Tank Soundings
TPL, TS = 1-89/52.00 = 0.04 hr = 130.85 s.
Average TpL?A = (130.85 + 146.36)/2 = 138.60 s.
Steady State Times
Based on Positive Displacement Meter
TSS,PD = T-TPL>PD = 720-146.36 = 573.64 s.
Based on Tank Soundings
TSS,TS = T-TpL,TS - 720-130.85 = 589.15 s.
Average
TSS,A = (TsS,PD+TsS,TS)/2 = (573.64+589.15)/2 = 581.40 s.
Oil Recovery
Using the stratified sampling technique. Steady state tank No. IV.
Initial volume =0.45 m^ oil.
Stratified
sample
compartment
1
2
3
4
Total
Representative
tank volume
m3
0.68
1.18
1.48
1.11
4.45
Percent,
oil, %
78
88
93
95.5
N/A
Total Oil
(m3)
0.53
1.04
1.37
1.06
4.00
70
-------
Collected volume = 4.45 - C.45 = -.00 m3 = VT
Collected oil volume = 4.00 - 0.45 = 3.55 m3 = VQ
Using grab sample technique.
Test four, slop tank.
Initial height = 64 mm
Total height = 851 mm
Decanted height = 731 mm
From linear interpolation of height-volume listing (tank calibration chart)
Initial volume = 0.31 m3
Total volume = 7.97 m3
Decanted volume = 6.45 m3
Oil percentage = 81% (from lab analysis of grab samples)
Total collected volume = 7.97-0.31 = 7.66 m3 = Vj
Total collected oil volume = (6.45-0.30(0.81) = 4.97 m3 = Vo
Calculation of Skimmer Rating Criteria (SRC)
Recovery Efficiency = RE = 100 (Vo/Vj)
Steady State
RE = (3.55/4.00X100) = 88.75%
Extended Steady State
RE = (3.55+4.97)7(4.00+7.66) xlOO = 73.07%
Oil Recovery Rate = ORR =
(Oil recovered in steady state)/(steady state time length)
Steady state
ORR = 3.55/0.10 = 35.5 m3/hr
Extended steady state
ORR = (3.55+4.97)7(0.10+0.17) = 31.56 m3/hr
Throughput efficiency
TE = (100 V0)/(Q)(tss)(E%)
Steady State (Repetitious calculations not shown)
TE = (100X3.55)/(49.28)(0.10X0.80) = 92.85%
Extended Steady State
TE = (100X3.55 +4.97)/(49.28)(0.27)(0.80) = 80.04%
71
-------
This ;-^:r,pie illustrates the data ca'cuiauons on Throughput efficiency. The
10% difference covers a range of possible values for TE between steady state and
extended steady state.
72
-------
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75
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SECTION 10
TEST RESULTS AND DISCUSSION
Ol ine eight tests run at sea with oij distribution, only the
dynamic skimmer rating criteria listed. The first test was run with only 0.60 I of oil
distributed mainly for visual sighting purposes. The second and third tests were run to
establish the quantity of unrecoverable oil in the Sock, to test the Sock for boom-type
oil keeping ability, and to determine the critical speed for oil loss primarily through
shedding and entrainment. The results of the oil tests are given in the test-to-test
summary. Tabie II summarizes the test results.
TEST ONE
A small sample (0.60 liter) of La Rosa crude oil was poured onto the water
surface directly in front of the Sock mouth. The oil spread evenly on the surface
forming a thin but visible slick of black oil. The contrast between the oil and water
was sufficient to visually observe the slick deposited on the sea, bow wave inter-
actions, the skimmer losses, and encounter efficiency.
TEST TWO
A total of 1.89 nn^ (500 gal) of La Rosa crude oil was distributed to detemine
the non-recoverable oil that is trapped in the Sock. Because of low water jet pressure,
only approximately 80% 1.5 m^ (400 gal) actually entered the Sock with a surface
current velocity of 1 kt. Visual estimates of 1 to 3 m^/hr (5 to 10 gpm) were made.
Part way through the test, the speed is reduced to 0.75 kt and the visual estimate of
oil loss was approximately 0.5 m^/hr (3 gpm) still as entrained droplets of the oil.
Later 1.6 m^ (423 gal) was recovered using the Tuthill positive displacement pump.
TEST THREE
A second volume of 1.89 m^ (500 gal) was distributed to the Sock and the
Powhatan speed varied to ascertain the critical speed for boom-type failure. The
shedding effects are obvious at 1 kt but much more pronounced at 1.5 kt. When
reaching the 1.75 to 2.0 kt range, the oil shed does not resurface until 5-10 m (15-30
ft) past the Sock. When the speed is reduced to 0.5 kt, a thick slick 1 m (3 ft) wide
forms and tapers to a point 5-7 m (5-20 ft) aft of the Sock. Vortices and SOCK
generated turbulence is apparent at speeds greater than 1 kt. Recovery of fluid in the
Sock yielded 0.68 m^ (57 gal) of oil.
TEST FOUR
The first of the large scale distribution tests employs a 12.5 m^ (3,300 gal) oil
dump, the first 1.89 m^ (500 gal) of which is considered to be preload. During the
76
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TABLE 11. SOCK TEST RESULTS
Pre-
load
m3
Dist
rate,
m3/hr
SOCK
pump,
1/3
H
m
Period
T,
s
Direc RE
to sea %
TE ORR
% m3/hr
Fwd
Test speed,
no. kt
1 2.1 .0005 --- --- 1.5 6 Head ---
2 1.0 1.89 66 --- 1.3 7 Head --- ---
3 0.75-
2.0 1.89 35 --- 1.4 7 Head ---
t 1.0 1.89 68 68 1.2 7 Head 44 55 10
5 1.3 3.8 47 45 0.9 5.5 Head 89 93 35
6 1.3 3.8 65 65 1.4 3.7 Head 39 47 12
7 1.75 3.8 23 23 1.0 4.3 Follow 43 43 12
8 2.1 3.8 29 29 0.7 5.8 Follow 26 18 2
77
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testing, a head wave is observed in the Sock v, nich tended tc force oil between the
Sock fabric and the pontoon flcetation at the nriouth of the Sock.
*<*»,,-
The Sock had a reJative surface velocity of 1 kt and the waves had a significant
(1/3) height of 1.2 m. The ORR was determined to be 10 m3/hr, the RE 44%, and the
TE 55%.
TEST FIVE
The fifth test was run at 1.3 kt using a 3.8 m^ (1,000 gal) preload distributing
oil at 47 m^/hr (200 gpm). The sea was rougher than earlier, the significant wave
height was lower (0.9 m) but the period was also shorter (5.5 seconds compared with
7.0 seconds on the fourth test).
The SOCK recovered oil at 35 m3/hr (154 gpm) with the RE = 89% and the TE =
93%. This was the test with the widest variation of results based on the differing
computed distribution rates and "steady state" versus "extended steady state". For
example, the Throughput Efficiency could vary from 74% to 93%.
TEST SIX
The relative surface speed remains at 1.3 kt for comparative purposes, and the
preload remains at 3.8 m^ (1,000 gal). The distribution rate was increased to 65 m^/hr
(300 gpm). The results are not, however, indicative that this changes the TE. Oil was
recovered at 12 m^/hr (53 gpm) giving a TE of 47% and a RE of 39%. Unfortunately
the sea state was an uncontrollable variable in the entire execution and the significant
wave height changed to 1.4 m cresting every 3.7 seconds during this test. Test six was
^*».- the last of the tests run into the seas.
TEST SEVEN
Run at 1.75 kt with the Sock in following seas, the oil was distributed at 23
(101 gpm) with a theoretical recovery rate set to be the same. The Sock
encountered waves 1 m in height cresting every 4.3 seconds. The skimmer recovered
oil at 12 m3/hr (53 gpm) with a RE of 43%, of a TE of 43%.
TEST EIGHT
The final test was run at a higher speed to observe significant fall off in
performance. Sea conditions were 0.7 m waves cresting every 5.8 seconds. The Sock
at 2.1 kt recovered oil at 2 m^/hr with a RE of 26% and a TE of 18%.
78
-------
REFERENCES
1. United States Navy, Naval Sea Systems Command, T-ATF 166 Class Operations
Handbook, NAVSEA 09Q5-LP-518-9010, April 1978.
2. Ayers, R.R. SOCK - "An Oil Skimming Kit for Vessels of Convenience," In:
Proceedings of the 1977 Oil Spill Conference, American Petroleum Institute,
New Orleans, Louisiana, 1977. pp. 361-366.
3. Tubb, Maretta. "Ocean Industry's 1979 Survey of the Marine Transportation
Fleet," Ocean Industry, February 1979, pp. 37-50.
4. Aalund, L.R., "Wide Variety of World Crudes Gives Refiners Range of Charge
Stock," The Oil and Gas Journal, March 29, 1976. pp. 87-89.
5. "Research Program Plan for Open Ocean Performance of the Spilled Oil
Containment Kit (SOCK)," Naval Sea Systems Command, Washington, D.C.,
May 2, 1979. 42 pp.
6. Ross, S.L. and M. Fingas. "Spill Technology Newsletter," Canadian Environ-
mental Protection Service, July-August 1979. p. 253.
7. Shonting D. and R. Robertson. "The New York Bight Experiment (NYBEX), a
Test of the SOCK; Environmental Observations," Naval Underwater Systems
Center, Newport, Rhode Island, June 20, 1980.
8. Letter EPA Region II to Naval Sea Systems Command, dated January 2, 1980,
Subject: Ocean Dumping Permit No. ll-DC-149-Research.
9. Lichte, H.W. Testing Skimmers for Offshore Spilled Oil. In: Proceedings of
the 1978 Offshore Technology Conference, Houston, Texas, 1978. pp. 247-254.
10. Littau, B., et al. "Marine Climatology", MESA New York Bight Atlas
Monograph 7, New York Sea Grant Institute, December 1976.
11. "Trim and Stability Booklet T-ATF Fleet Tug," Nickum & Spaulding Associates,
Inc., Seattle, Washington, July 1979 revision.
12. Cohen, S.H. "Notes on SOCK Skimmer Offshore Test," Hydronautics, Inc.,
Laurel, Maryland, Project 8038, April 1980.
13. Dennison, Gene. "Report of Analysis", Job No. 11124/88, Princeton Testing
Laboratory, May 28, 1980.
79
-------
H. Miller, E, et__a.. ''.r.alysiS M Light *e:g'-.t Oil Cor^c-irvr.erit Sysierr, Sea Trials,"
CG-D-22-7^. U.S. Department ol Tran^po-tctton, United States Coast Guard,
Office of Research and Development, V,'as:J-gion, D.C., 1973. 13^ pp.
80
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APPENDIX
PARTICIPATING ORGANIZATIONS
Yeson & Hanger-Silas Mason Co., Inc.
Tidewater Contractors, Inc.
Nava] Underwater Systems Center
University of Rhode Island
Naval Weapons Station Earle
Crowiey Environmental Services Corp.
United Tank Containers
Film Flair
Hydronautics, Inc.
3rd Coast Guard District, COTP
Region II, USEPA
Military Sealift Command, USN
National Weather Service, NOAA
Research and Development Office, USEPA
Shell Development Company
Research and Development Headquarters, USCG
NAVSEA, USN
Shell Oil Company
NAVFAC, USN
SUPSALV, USN
Cutter Reliance, USCG
81
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1 REPORT NO.
2.
4. TITLE ANDSUBTITLE
Tests of The Shell SOCK Skimmer Aboard USNS POWHATAN
7. AUTHOR(S)
H. W. Lichte, M. Borst, and G. F. Smith
9. PERFORMING ORGANIZATION NAME Ah>
Mason & Hanger-Silas Mason
P.O. Box 11?
Leonardo, NJ 07737
12. SPONSORING AGENCY NAME AND ADC
Municipal Environmental Re
Office of Research and De\
U.S. Environmental Protect
Cincinnati, Ohio ^5268
JD ADDRESS
Co . , Inc .
JRESS
ssearch Laboratory
relopment
;ion Agency
3. RECIPIENT'S ACCESSION-NO.
5. REPORT DATE
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
INE826
11. CONTRACT/GRANT NO.
68-03-26142
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/1 >4
15. SUPPLEMENTARY NOTES
Richard A. Griffiths, Project Officer (201-321-6629)
16. ABSTRACT
The Spilled Oil Containment Kit (SOCK), developed by Shell Development Company,
was tested in a controlled crude oil dumping off the New Jersey Coast in early 1980.
The program was sponsored by the U.S. Navy, Director of Ocean Engineering, Supervisor
of Salvage through the Oil and Hazardous Materials Simulated Environmental Test Tank
(OHMSETT) Interagency Technical Committee. The skimmer had been designed as a
physical attachment to an oil industry work boat in a vessel-of -opportunity deploy-
ment mode. The United States Naval Ship (USNS)Powhatan T-ATF fleet tug was chosen
as a similar vessel and one that had an oil spill recovery operation mode.
The test program is described, including the oil/water distribution and
collection system, deployment and retrieval of the SOCK, the onboard fluid
measurement, data analysis, logistics, weather and environment measurements, and
the Powhatan/SOCK interface. The light crude oil and ocean water collected were
stored aboard the vessel and decanted; the emulsified oil was later sold as waste oil.
Eight experimental crude oil dumps are described and anlyzed. The sea conditions
varied from calm to 1.8-m significant wave heights. During the 6 days at sea, 50m3
of oil were dumped, and the skimmer collected 32 m of oil.
The program is, analyzed for future improvements to open ocean testing plans
incorporating oil skimmers with and without vessels of opportunity.
17.
a. DESCRIPTORS
Performance Tests
Skimmers
Water Pollution
Oils
13. DISTRIBUTION STATEMENT
Release to public
KEY WORDS AND DOCUMENT ANALYSIS
b. IDENTIFIERS/OPEN ENDED TERMS
Spilled Oil Cleanup
Coastal Water
Vessel-of -Opportunity
19. SECURITY CLASS (This Report/
TTNRT.ASRTFTED
20. SECURITY CLASS (This page)
UNCLASSIFIED
c. COSATI Field/Group
21. NO. OF PAGES
Q1
22. PRICE
EPA Form 2220-1 (9-73)
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