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A grab sample of the flooded dock was collected and a composite of
samples collected at each two-foot water level drop was made during
dewatering. Samples were taken of the drainage water during hosedown
following initial dewatering and regularly throughout the monitoring
period. Every two minutes during the pumping cycle, samples were
drawn and composited.
During the May 1976 sampling program at Shipyard D, the harbor water
was actually higher in certain constituents, such as total suspended
solids and pH, than in the NPDES tests. No significant increases
occurred between corresponding influents and effluents. As in samples
at other shipyards, discharge levels tend to be very low With rare
"high" values of certain parameters. It could not be established that
dockside activities affect discharge levels. As in the case of
Shipyards A and B, constituent levels remain constant throughout.
Only levels of manganese varied from the harbor water concentrations.
In all likelihood, this can be attributed to groundwater infiltration
since no other major source of manganese is apparent. The results
again lead to the conclusion that the nature of the discharge is not
conducive to numerical monitoring.
Several obstacles exist with respect to conducting an accurate
sampling program of floating drydocks and/or graving docks. Some of
these problems are due to the nature of the operation and drydock
design. Other difficulties occur during interpretation of the data.
o The physical design and operation of a floating drydock is
not conducive to conducting an effective sampling program.
During submersion of the dock, potential contaminants such
as grit and paint might be flushed from the surface of the
dock, rather than discharged through a single sampling point
such as a pipe or sewer, as in the case with graving docks.
When the dock is submerged, grit, spent paint, oil and
grease, and other dockside wastes may be flushed or may
float from the dock floor. Any spills, stormwater, or
discharges onto the floated dock floors will randomly run
off the ends and through scuppers along the sides of the
floating drydock. Since there are multiple discharge
points, accurate sampling is not feasible.
o Because only total drainage discharges were monitored on a
daily basis, it is difficult to attribute constituents and
flows to any individual source or operation. For example,
variations in flows and composition of cooling water and
degree of hydrostatic relief might occur concurrently with
an operation such as blasting or painting. Any alteration
in drainage discharge would be difficult to correlate with
these activities.
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Shipyard D management once attempted to estimate all drydock
discharge parameters and levels but were unable to determine
the source of some of the contaminants- The problem
obviously is complex.
o Insufficient documentation of sampling programs performed
prior to this contract makes interpretation of previous
monitoring questionable. By failing to explain what
shipyard operations were in progress, weather conditions,
floor conditions, and especially analytical procedures,
interpretation and comparison of monitoring data is
difficult.
o The lack of a "typical" daily dock operation means that all
data obtained is particular to that specific day and is not
necessarily representative of the usual drydock discharges.
Consequently interpretation of the data is difficult. This
restricts determination of sources and establishment of
recommendations.
Leaching Studies
Studies of the leachability of the fresh abrasive and spent abrasive
and paint were done at several shipyards. The experiments are
discussed below. >
Leaching Study tl consisted of an experiment in which 400 grams of
spent abrasive collected from a shipyard facility were mixed with a
liter of seawater. The combination was shaken intermittently. A 100
ml aliquot was withdrawn after two days one inch below the surface.
Another aliquot was withdrawn after eight days. The method of
analysis was not defined. The two aliquots produced no difference in
concentrations of Cd, Cr, Zn, Cu, and Sn. Only levels of lead showed
a significant increase.
The results of leaching Study f2 present markedly different
conclusions. These tests performed by EPA indicate that the spent
abrasive may actually act as an adsorbent of metals already present in
the water. Approximately 100 grams of spent abrasive collected at
five different shipyards were each exposed to approximately one Ixter
of seawater from the local bay. An analysis indicated that cadmium,
chromium, lead, and tin levels all either remain the same or
decreased. Only copper and zinc exhibited -any increase in
concentration.
Leaching Study f3 resulted in no major change in nickel, zinc, tin, or
cadmium. Slight increases in chromium, copper, iron, and lead levels
occurred, but mercury concentration was reduced 98 percent.
-------
The data for Leaching Study i4 was much more thorough. Seven spent
abrasive samples and two fresh abrasive samples were subjected to a
leaching test in seawater. A level of pollutant was determined after
exposure of 300 hours and 700 hours. Only lead concentrations
markedly increased with each sample. Copper and zinc levels increased
significantly on occasions, but otherwise remained constant. Arsenic,
cadmium, mercury, and tin concentrations never varied appreciably.
Levels of copper, lead, and zinc in the liquid consistantly
corresponded to the levels in the spent abrasive. Similarly low
values of these metals in the liquid samples occurred when the spent
abrasive contained lesser quantities of these three elements.
Leaching Study f5 consisted of treating five different samples of grit
and river sediment with river water or deionized water. Some of the
experiments involved stirring, while others did not. Chromium levels
actually showed a slight decrease in value, indicating again the
possibility that the abrasive acts in certain cases as an adsorbent.
Copper levels changed very little. Data on leachability of zinc was
inconclusive since concentrations of zinc increased in some instances
and decreased in others,
There are many inconsistencies in the results of the five leaching
studies reviewed. Questions which remain about testing procedures and
conflicting data indicate that further study would be beneficial.
Doubts exist about the reliability of a leaching test done in a small
closed container where dilution and circulation are not factors.
Sieve Analyses of Debris
Sieve analyses were conducted on fresh grit and spent paint and
abrasive collected by the contractor at Shipyard B. One sample
consisted entirely of fresh abrasive, and the second sample containing
spent paint and grit was collected from the drydock floor immediately
following blasting. The two samples were analyzed using a standard
sieve analysis and the results are shown in Table V-ll and V-12.
Table V-11. GRAIN- SIZE ANALYSIS
OF UNSPENT GRIT (SAMPLE 1)
Sieve % Retained % Finer
10 15 85
HO 83 2
60 1.8 .2
200 <. 1 <. 1
<200 <. 1 <- 1
100
Average specific gravity = 4.617
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Table V-12. GRAIN-SIZE ANALYSIS OF
SPENT GRIT AND SPENT PAINT (SAMPLE 2)
Sieve % Retained % Finer
10 10 90
40 78 1?
60 66
140 3 3
200 1 2
<200 2_ 1
100
Average specific gravity =4.418
The fresh grit, "Black Beauty," was purchased by the company from
power plants. The abrasive is actually the slag collected from coal-
fired boilers. The principal constituents are iron, aluminum, and
silicon oxides (see Table III-3). The spent grit and paint, which
were collected following a "very light sand sweep," contained flakes
and particles of antifouling and primer paints aind bits of iron
oxides. The test results indicate that over 95 percent of the
particles in each sample were sand size and were regained in U.S.A.
Standard Testing sieves numbered 10, 40, 60, and 140, made by Tyler
Equipment Co., with the largest fraction retained in sieve number 40.
The unspent grit particles were slightly larger aind the facets were
sharper and more defined. The specific gravities of the two samples
did not differ significantly. These sand-size particles were readily
settleable.
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SECTION VI
SELECTION OF POLLUTION PARAMETERS
INTRODUCTION
Materials originating from shipbuilding and repair activities which
may have significance as potential pollutants have been identified
during the course of this study. Although an exhaustive list of
materials capable of discharge to waterways could be developed, many
of these can be eliminated from consideration. The priority
pollutants copper/ zinc, chromium, and lead have been identified as
being present in shipyard facilities under conditions which can result
in their discharge. Compounds of these metals are constituents of
fresh paints (Tables III-4 and III-5). They persist in the abrasive
blasting debris as components of the spent paint and abrasive. Tne
rationale for selection of constituents as pollution parameters or for
rejection of others is presented here.
While numerical guidelines and standards are not being recommended at
this time, pollution parameters are being identified for consideration
by the users of this document and for further investigation, and use
where it may be appropriate.
Factors which have been considered in selecting and rejecting
pollution parameters include:
o The degree of pollutional constituents used and discharged
from ship repair and construction operations in graving
docks and floating drydocks.
o The need for preventing the introduction of the constituent
into the waterway; and
o The aesthetic effects of the constituent and the effects on
other uses of the water.
A list of constituents which may be subject to discharge from graving
docks and from floating drydocks is shown in Table VI-1. Pollution
parameters have been selected from this list, and this is discussed in
the following sections.
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Table VI-1. MATERIALS ORIGINATING FROM
DISCHARGED TO WATERWAYS
DRYDOCKS WHICH MAY BE
Constituents
Fresh Grit
Blasting Debris
Solid Wastes
Fresh Paint
Oil & Grease
Fuel
Oil, Grease and
Fuel Contaminated
Water
Solvents, Paint
Remover
Boiler Water
Cooling Water
Hydrostatic
Leakage
Gate Leakage
Source
Spills during transfer
and handling
Material removed from
ships hull during
blasting
Repair and Construc-
tion Activities
Paint mixing spills,
overspray
Spills and leakage
from ship and equip-
ment, losses during
servicing
Leakage from tank
cleaning and ruptured
tanks, bilgewater
Paint stripping
other than blasting
Vessel boiler
Vessel equipment
Groundwater leakage
into dock
Harbor water
Comments
Uncontaminated
solid, usually slag,
sand, cast iron or
steel shot
Spent grit, marine
fouling, spent paint,
rust, may contain
priority pollutants
Scrap metal, welding
rods, wood, plastics,
trash such as paper
and food scraps
Overspray may reach
dock floor, spills
to floor or drains
and contains prior-
ity pollutants
Can originate either
from vetssel or from
dock activities
May contain detergents
used in tank cleaning
Not common practice
High quality water,
usually not discharged
Supplied by on-shore
source, once-through,
non-contact
Graving docks only
Graving docks only
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Materials identified in Table VI-1 may produce other contaminants in
water. Their effects are generally measured in terms of parameters
such as suspended solids, dissolved solids, BOD and COD, oil and
grease, and specific elements or chemical species. Table VI-2 lists
specific and nonspecific parameters which are possible pollutants.
Analytical methods for monitoring would necessarily include some or
all of the items listed in Table VI-2.
. *
Table VI-2. PARAMETERS WHICH MAY BE PRESENT IN
WASTEWATER DISCHARGES FROM DRYDOCKS
Specific Parameters Non-specific
Metals Non-Metals Parameters
Pb Mn P0« pH
Cr As NO2 Total Suspended Solids
Cu Hg Settleable Solids
Sa Ni Oil and Grease
Cd Al
Zn Fe
RATIONALE FOR THE SELECTION OF POLLUTION PARAMETERS
During the course of this study and the sampling program conducted in
support of it, it has become evident that a direct cause and effect
relationship between activities and materials in the docking facility
and constituents in the wastewater does not always exist. In
addition, much of the water purposefully used in drydocking operations
is harbor water already containing measurable levels of constituents
leached from the drainage area supplying the harbor, discharged from
other sources, or naturally present in the water. Because of this,
the problem of identifying the origin of these constituents, in the
presence of sampling and analytical variations, becomes complex.
In selecting pollution parameters two questions have been considered
as vital to the proper inclusion of a constituent in this category.
The first of these is, "Are the constituents discharged to the
environment"? Second, and equally important is, "Is the constituent
present in the ship repair and construction facility in a condition
capable of creating a hazardous discharge"? If both of these questions
can be answered in the affirmative, the constituent should be
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considered a potential pollutant
necessitating controls.
requiring monitoring and possibly
Referring to Table VI-2, the listed metals all may be constituents of
the paint used on hulls. The most commonly used anticorrosive paints
contain zinc chromate or lead oxide. Antifouling paints in current
use usually incorporate cuprous oxide. The use of arsenic and mercury
antifouling paints has been discontinued because of their toxicity.
Recently, antifouling paints containing organotin compounds have been
introduced into practice. These have the advantage of longer life in
service but when removed for repainting, like mercury based paints,
can be toxic to workers. Three sources of iron exist in the
drydocking facility. Steel scrap and waste metal are major sources.
Iron from scrap is initially in the metallic form Jout air and moisture
will rapidly produce a surface coat of rust. The second source is
iron oxide contained in the paints. The amount of iron oxide in paint
is negligible compared to the other paint components and to exposed
steel surfaces found in the drydock area. The third source is
metallic iron abraded from ships during abrasive blasting and
subsequent potential dissolution into water.
Non-metal constituents are phosphates and nitrites. These are added
to water in trace quantities during wet blasting to bare metal. They
function as rust inhibitors. Their use is infrequent and total
quantities are small.
Non-specific parameters which may ultimately be transported to
wastewater are also listed in Table VI-2.
Solids content is measured by total solids, suspended and settleable
solids, and dissolved solids. Total solids is the total of the
suspended and dissolved components. Most of the suspended solids are(
spent paint and grit from the blasting operations, but may also
include dried fresh paint resulting from overspray and spills. Other
sources of solids are metal or metal scale particulates resulting from
cutting and cleaning work, slag from arc weldiLng, wood and other
organic solids particles, etc., all in small quantities. Dissolved
solids may be present due to constituents from spent or fresh paint,
solution of iron or alloy metals from scrap steel, and solution of
components from virtually any solid coming in contact with water.
A measure of the hydrogen ion concentration of water is pH. As such,
it can be altered (from the neutral value of 7) to either acidic or
basic values by the effects of dissolved materials added to the water.
Oil and grease are measures of the quantity of organic compounds
extractable by hexane. This can include not only oils and greases,
but also fuel, solvents, and paint components.
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The parameters selected as pollutants potentially released by shipyard
activities into wastewaters are listed in Table VI-3. These
constituents represent materials which are commonly, used in drydocking
facilities and hence which have potential for release to ambient
waters. Although other parameters listed in Table VI-2 have been
rejected as pollutants to be regulated at this time, the sampling and
analysis program routinely determined the levels of those as well.
The basis for rejection is discussed in the subsection on "Rationale
for Rejection of Pollution Parameters."
Table VI-3. POLLUTION PARAMETERS
Specific Parameters .
Priority Other Non-Specific
Pollutants Non-Metals Metals Parameters
Zn None Sn* Suspended Solids
Cu Settleable Solids
Pb Oil and Grease
Cr pH
*Only where organotin anti-fouling plants may be
used or removed from the hull.
It must be emphasized that one of the great uncertainties in
establishing pollution parameters arises from the use of harbor water
for most of the shipyard operations. Unlike chemical processing
plants, where high quality water is used, input water may vary in
constituent concentration fron fresh lake and river water to saline
ocean water, thus the background content of suspended and dissolved
components may mask many of the parameters frequently monitored. The
following subsections discuss each of the parameters selected as
potential pollutants.
Zinc (Zn)
Occurring abundantly in rocks and ores, zinc is readily refined into a
stable pure metal and is used extensively as a metal, an alloy, and a
plating material. In addition, zinc salts are also used in paint
pigments, dyes, and insecticides. Many of these salts (for example,
zinc chloride and zinc sulfate) are highly soluble in water; hence, it
is expected that zinc might occur in many industrial wastes. On the
other hand, some zinc salts (zinc carbonate, zinc oxide, zinc sulfide)
are insoluble in water and, consequently, it is expected that some
zinc will precipitate and be removed readily in many natural waters.
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In soft water, concentrations of zinc ranging from 0.1 to 1.0 mg/1
have been reported to be lethal to fish. Zinc is thought to exert its
toxic action by forming insoluble compounds with the mucous that
covers the gills, by damage to the gill epithelium, or possibly by
acting as an internal poison. The sensitivity of fish to zinc varies
with species, age, and condition, as well as with the physical and
chemical characteristics of the water. Some acclimatization to the
presence of the.zinc is possible. It has also been observed that the
effects of zinc poisoning may not become apparent immediately so that
fish removed from zinc-contaminated to zinc-free water may die as long
as 'US hours after the removal. The presence of copper in water may
increase the toxicity of zinc to aquatic organisms, while the presence
of calcium or hardness may decrease the relative toxicity.
A complex relationship exists between zinc concentrations, dissolved
oxygen, pH, temperature, and calcium and magnesium concentrations.
Prediction of harmful effects has been less than reliable and
controlled studies have not been extensively documented..
Concentrations of zinc in excess of 5 mg/1 in public water supply
sources cause an undesirable taste which persists through conventional
treatment. Zinc can have an adverse effect on man eind animals at high
concentrations.
Observed values for the distribution of zinc i*i ocean waters vary
widely. The major concern with zinc compounds in marine waters is not
one of acute lethal effects, but rather one of the long term sublethal
effects of the metallic compounds and complexes. From the point of
view of acute lethal effects, invertebrate marine animals seem to be
the most sensitive organisms tested.
A variety of freshwater plants tested manifested harmful symptoms at
concentrations of 10 mg/1. Zinc sulfate has also been found to be
lethal to many plants and it could impair agricultural uses of the
water.
Copper (Cu)
Copper is an elemental metal that is sometimes found free in nature
and is found in many minerals such as cuprite, meilachite, azurite,
chalcopyrite, and hornite. Copper is obtained from these ores by
smelting, leaching, and electrolysis. Significant industrial uses are
in the plating, electrical, plumbing, and heating equipment
industries. Copper is also commonly used with other minerals as an
insecticide and' fungicide.
Traces of copper are found in all forms of plant and animal life, and
it is an essential trace element for nutrition. Copper is not
considered to be a cumulative systemic poison for humans as it is
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readily excreted by the body, but it can cause symptoms of
gastroenteritis, with nausea and intestinal irritations, at relatively
low dosages. The limiting factor in domestic water supplies is taste.
Threshold concentrations for taste have been generally reported in the
range of 1.0 to 2.0 mg/1 of copper while concentrations of 5 to 7.5
mg/1 have made water completely undrinkable. It has been recommended
that the copper in public water supply sources not exceed 1 mg/1.
Copper salts cause undesirable color reactions in the food industry
and cause pitting when deposited on some other metals such as aluminum
and galvanized steel. The textile industry is affected when copper
salts are present in water used for processing of fabrics. Irrigation
waters containing more than minute quantities of copper can be
detrimental to certain crops. The toxicity of copper to aquatic
organisms varies significantly, not only with the species, but also
with the physical and chemical characteristics of the water, including
temperature, hardness, turbidity, and carbon dioxide content. In hard
water, the toxicity of copper salts may be reduced by the
precipitation of copper carbonate or other insoluble compounds. The
sulfates of copper and zinc, and of copper and cadmium are synergistic
.in their toxic effect on fish.
Copper concentrations less than 1 mg/1 have been reported to be toxic,
particularly in soft water, to many kinds of fish, crustaceans,
mollusks, insects, phytoplankton, and zooplanton. Concentrations of
copper, for example, are detrimental to some oysters above 0.1 ppm.
Oysters cultured in seawater containing 0.13 to 0.5 ppm of copper
deposited the metal in their bodies and became unfit as a food
substance. "
Tin (Sn)
Tin is not present in natural water, but it may occur in industrial
wastes. stannic and stannous chloride are used as mordants for
reviving colors, dyeing fabrics, weighting silk, and tinning vessels.
Stannic chromate is used in decorating porcelain, and stannic oxide is
used in glass works, dye houses, and for fingernail polishes. Stannic
sulfide is used in some lacquers and varnishes. Tin compounds are
also used in fungicides, insecticides, and anti-helminthics.
No reports have been uncovered to indicate that tin is detrimental in
domestic water supplies. Traces of tin occur in the human diet from
canned foods, and it has been estimated that the average diet contains
17.14 mg of tin per day. Man can apparently tolerate 850 to 1000 mg
per day of free tin in his diet.
On the basis of feeding experiments, it is unlikely that any
concentration of tin that could occur in most natural waters would be
detrimental to livestock. Most species of fish can withstand fairly
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large concentrations of tin; however, tin is about ten times as toxic
as copper to certain marine organisms such as barnacles and tubeworms.
While the inorganic compounds of tin are essentially non-toxic at the
levels normally encountered, organotin compounds exhibit a high degree
of toxicity to specific organisms. These are relatively recent
innovations and little experience has been developed in their use.
Due to the potential hazards of organotins to marine environments and
in light of the present lack of knowledge concerning the behavior of
organotin waste in the environment, abrasive blasting waste containing
organtin compounds should be considered pollutants oi: concern.
Lead (Pb)
Lead is used in various solid forms both as a pure metal and in
several compounds. Lead appears in some natural waters, especially in
those areas where mountain limestone and galena are found. Lead can
also be introduced into water from lead pipes by the action of the
water on the lead.
Lead is a toxic material that is foreign to humans and animals. The
most common form of lead poisoning is called plumbism. Lead can be
introduced into the body from the atmosphere containing lead or from
food and water.
Lead cannot be easily excreted and is cumulative in the body over long
periods of time, eventually causing lead poisoning with the ingestion
of an excess of 0.6 mg per day over a period of years. It has been
recommended that 0.05 mg/1 lead not be exceeded in public water supply
sources.
Chronic lead poisoning has occurred among animals at levels of 0.18
mg/1 of lead in soft water and by concentrations under 2.4 mg/1 in
hard water. Farm animals are poisoned by lead more frequently than
any other poison. Sources of this occurrence include paint and water
with the lead in solution as well as in suspension. Each year
thousands of wild waterfowl are poisoned from lead shot that is
discharged over feeding areas and ingested by the waterfowl. The
bacterial decomposition-of organic matter is inhibited by lead at
levels of 0.1 to 0.5 mg/1. ^r.oi- r;v -
Fish and other marine life have had adverse effects from lead and
salts in their environment. Experiments have shown that small
concentrations of heavy metals, especially of lead, have caused a film
of coagulated mucous to form first over the gills and then over the
entire body probably causing suffocation of the fish due to this
obstructive layer. Toxicity of lead is increased with a reduction of
dissolved oxygen concentration in the water.
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Chromium (Cr)
Chromium is an elemental metal usually found as a chromite (FeCr^OO) .
The metal is normally processed by reducing the oxide with aluminum.
Chromium and its compounds are used extensively throughout industry.
It is used to harden steel and as an ingredient in other useful
alloys. Chromium is also used in the electroplating industry as an
ornamental and corrosion resistant plating on steel and can be used in
pigments and as a pickling acid (chromic acid)..
The two most prevalent chromium forms found in industry wastewaters
are hexavalent and trivalent chromium. Chromic acid used in industry
is a hexavalent chromium compound which is partially reduced to the
trivalent form during use. Chromium can exist as either trivalent or
hexavalent compounds in raw waste streams. Hexavalent chromium
treatment involves reduction to the trivalent form prior to removal of
chromium from the waste stream as a hydroxide precipitate.
Chromium, in its various valence states, is hazardous to man. It can
produce lung tumors when inhaled and induces skin sensitizations.
Large doses of chromates have corrosive effects on the intestinal
tract and can cause inflammation of the kidneys. Levels of chromate
ions that have no effect on man appear to be so low as to prohibit
determination to date. The recommendation for public water supplies
is that such supplies contain no more than 0.05 mg/1 total chromium.
The toxicity of chromium salts to fish and other aquatic life varies
widely with the species, temperature, pH, valence of the chromium and
synergistic or antagonistic effects, especially that of hard water.
Studies have shown that trivalent chromium is more toxic to fish of
some types than hexavalent chromium. Other studies have shown
opposite effects. Fish food organisms and other lower forms of
aquatic life are extremely sensitive to chromium and it also inhibits
the growth of algae. Therefore, both hexavalent and trivalent
chromium must be considered harmful to particular fish or organisms.
Total Suspended Solids (TSS)
Suspended solids include both organic and inorganic materials The
inorganic compounds include sand, silt, and clay. The organic
fraction includes such materials as grease, oil, tar, and animal and
vegetable waste products. These solids may settle out rapidly and
bottom deposits are often a mixture of both organic and inorganic
solids. Solids may be suspended in water for a time, and then settle
to the bed of the stream or lake. These solids discharged with man's
wastes may be inert, slowly biodegradable materials, or rapidly
decomposable substances. While in suspension, they increase the
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turbidity of the water, reduce light penetration, and impair the
photosynthetic activity of aquatic plants.
Suspended solids in water interfere with many industrial processes,
cause foaming in boilers, and incrustations on equipment exposed to
such water, especially as the temperature rises. They are undesirable
in process water used in the manufacture of steel, in the textile
industry, in laundries, in dyeing, and in cooling systems.
Solids in suspension are aesthetically displeasing. When they settle
to form sludge deposits on the stream or lake bed, they are often
damaging to the life in water. Solids, when transformed to sludge
deposits, may do a variety of damaging things , including blanketing
the stream or lake bed and thereby destroying the living spaces for
those benthic organisms that would otherwise occupy the habitat. When
of an organic nature, solids use a portion of all. of the dissolved
oxygen available in the area. Organic materials also serve as a food
source for sludgeworms and associated undesirable organisms.
Disregarding any toxic effect attributable to substances leached out
by water, suspended solids nay kill fish and shellfish by causing
abrasive injuries and by clogging gills and respiratory passages of
various aquatic fauna. Indirectly, suspended solids are inimical to
aquatic life because they screen out light, and they promote and
maintain the development of noxious conditions through oxygen
depletion. This results in the killing of fish and fish food
organisms. Suspended solids also reduce the recreational value of the
water.
Oil and Grease
Because of widespread use, oil and grease occur often in wastewater
streams. These oily wastes may be classified as follows:
o Light Hydrocarbons - These include light fuels such as
gasoline, kerosene, jet fuel, and miscellaneous solvents
used for industrial processing, degreasing, or cleaning
purposes. The presence of these light hydrocarbons may make
the removal of other heavier oily wastes more difficult.
o Heavy Hydrocarbons, Fuels, and Tars - These include the
crude oils, diesel oils, §6 fuel oil, residual oils, slop
oils, and in some cases, asphalt and road tar.
o Lubricants and Cutting Fluids - These generally fall into
two classes: non-emulsifiable oils such as lubricating oils
and greases and emulsifiable oils such as water soluble
oils, rolling oils, cutting oils, and drawing compounds.
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Emulsifiable oils may contain fat soap or various other
additives.
o Vegetable and Animal Fats and Oils - These originate
primarily from processing of foods and natural products.
These compounds can settle or float and may exist as solids or liquids
depending upon factors such as method of use, production process, and
temperature of wastewater. -
Oils and grease even in small quantities cause troublesome taste and
otlor problems. Scum lines from these agents are produced on water
treatment basin walls and other containers. Fish and waterfowl are
adversely affected by oils in their habitat. Oil emulsions may adhere
ta the gills of fish causing suffocation, and the flesh of fish is
tainted when microorganisms that were exposed to waste oil are eaten.
Deposition of oil in the bottom sediments of water can serve to
inhibit normal benthic growth. Oil and grease exhibit an oxygen
demand.
Levels of oil and grease which are toxic to aquatic organisms vary
greatly, depending on the type and the species susceptibility.
However, it has been reported that crude oil in concentrations as low
as 0.. 3 mg/1 is extremely toxic to freshwater fish. It has been
recommended that public water supply sources be essentially free from
oil and grease.
Oil and grease in quantities of 100 1/sq km (10 gallons/sq mile) show
up as a sheen on the surface of a body of water. The presence of oil
slicks prevent the full aesthetic enjoyment of water. The presence of
oil in water can also increase the toxicity of other substances being
discharged into the receiving bodies of water. Municipalities
frequently limit the quantity of oil and grease that can be discharged
t0> their wastewater treatment systems by industry.
i.i x ji.j a^-9' ^.srfOjt .
Acidity and Alkalinity (pH)
:-" if-' _.-,".
Although not a specific pollutant, pH is related to the acidity or
alkalinity of a wastewater stream. It is not a linear or direct
measure of either, however," it may be used properly as a surrogate to
control both excess acidity and excess alkalinity in water. The term
pH is used to describe the hydrogen ion - hydroxyl ion balance in
water. pH measures the hydrogen ion concentration or activity present
in a given solution. pH numbers are the negative common logarithm of
tlse hydrogen ion concentration. A pH of 7 indicates neutrality or a
balance between free hydrogen and free hydroxyl ions. A pH above 7
indicates that the solution is alkaline, while a pH below 7 indicates
that the solution is acid.
77
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Knowledge of the pH of water or wastewater is useful in determining
necessary measures for corrosion control, pollution control, and
disinfection. Waters with a pH below 6.0 are corrosive to water works
structures, distribution lines, and household plumbing fixtures and
such corrosion can add constituents to drinking water such as iron,
copper, zinc, cadmium, and lead. Low pH waters not only tend to
dissolve metals from structures and fixtures but also tend to
redissolve or leach metals from sludges and bottom sediments. The
hydrogen ion concentration can affect the "taste" of the water and at
a low pH, water tastes "sour."
Extremes of pH or rapid pH changes can exert stress conditions or kill
aquatic life outright. Even moderate changes from "acceptable"
criteria limits of pH .are deleterious to some specie's. The relative
toxicity to aquatic life of many materials is increased by changes in
the water pH. For example, metalocyanide complexes can increase a
thousand-fold in toxicity with a drop of 1.5 pH units. Similarly, the
toxicity. of ammonia is a function of pH. The bactericidal effect of
chlorine in most cases is less as the pH increases, and ,it is
economically advantageous to keep the pH close to 7..,
Acidity is defined as the quantitative ability of a water to
neutralize hydroxyl ions. It is usually expressed as the calcium
carbonate equivalent of the hydroxyl ions neutralized. Acidity should
not be confused with pH value. Acidity is the quantity of hydrogen
ions which may be released to react with or neutralize hydroxyl ions
while pH is a measure of the free, hydrogen ions in a solution at the
instant the pH measurement is made. A property of many chemicals,
called buffering, may hold hydrogen ions in a solution from being in
the free state and being measured as pH. The bond of mpst buffers is
rather weak and hydrogen ions tend to be released from the buffer as
needed to maintain a fixed pH value.
Highly acid waters are corrosive to metals, concrete and living
organisms, exhibiting the pollutional characteristics outlined above
for low pH waters. Depending on buffering capacity,, water may have a
higher total acidity at pH values of 6.0 than other waters with a pH
value of 4.0.
RATIONALE FOR REJECTION OF POLLUTION PARAMETERS
A number of parameters shown in Table VI-2 have been rejected as
pollution parameters. This rejection was based on negative answers to
one or both of the questions used to select pollution parameters.
Rejected parameters are listed in Table VI-4. A brief discussion of
the rejected parameters and the rationale follows.
78
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Table VI-4. PARAMETERS REJECTED AS POLLUTION PARAMETERS
Specific Parameters Non-Spedfie
Metals Non-Metals Parameters
As Mn PO4 Total Solids
Hg Al NO2 Dissolved Solids
Fe COD
Cd BOD
Ni
Arsenic has been rejected because its use in"antifouling paints has
been discontinued due to toxicity. Mercury also formerly was included
as a constituent of antifouling paints. However, on March 29, 1972,
the EPA suspended its use in marine paints, and since that use was not
subject to appeal (although its use in other paint formulations was
appealed), it no longer is found in shipbuilding and repair
facilities. If further investigation reveals the presence of arsenic
in foreign paints which are subsequently removed in U.S. facilities,
then it shall become a selected pollutant.
Iron has been rejected because, except for trace quantities in spent
paint both as a pigment component and as rust blasted from the hulls,
its presence in shipbuilding and repair facilities is in the form of
structural steel, or at levels below immediate concern.
Cd, Ni, and Mn are unlikely constituents to arise from shipyard
operations. No uses of these materials in shipyards have been
identified. Aluminum may be present but is not considered a
significant pollutant. Aluminum in the form of alum is commonly used
in water treatment plants.
Phosphates and nitrites have been eliminated. Both are potentially
detrimental to natural water bodies, but the only source is from wet
blasting to bare metal. In this operation they are added to the water
in fractional percentages as rust inhibitors. Wet blasting to bare
metal is rarely used in shipyard practice because of the formation of
rust on the unpainted surface.
COD and BOD have also been rejected. COD occurs as a result of the
presence of reducing chemical compounds in the wastewater. The only
reducing chemical species identified are nitrites, and these have been
rejected as a parameter. BOD results from biological (sanitary)
wastes and is not within the scope of this study.
79
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SECTION VII
TREATMENT AND CONTROL TECHNOLOGY
-,',-, \
INTRODUCTION
,: i.=;--i.;p !'
Treatment and control of shipyard discharges is subject«*o problems
not encountered in most industries. One example is the volume of
water involved in graving dock dewatering or raising floating
drydocks. Graving dock volumes shown in Table III-8 range from 3.8
million liters (1.0 million gallons) to 246 million liters (65 million
gallons). Dewatering may be carried out in four hours or less and at
the upper size extreme the flowrate during dewatering would be 60
million liters (16 million gallons) per hour or the equivalent of 476
million liters (390 million gallons) per day. Floating drydocks are
open ended, and confinement of volumes of water equivalent to that
found in graving docks would make it impossible to raise the dock.
Thus, flooding and dewatering operations defy practical wastewater
treatment. -- -
There are, however, a number of practices which can potentially
benefit the discharges of industrial and other waters from both
graving docks and floating drydocks. In the course of this study,
these practices, which constitute the treatment and control technology
in use or under development, were observed or reported to the
contractor by facilities visited or contacted. - '
Seven facilities were visited and thirty-eight were contacted by
telephone. From the information obtained, the treatment and control
technology in use basically consists of (1) clean-up procedures in the
dock and (2) control of water flows within the dock. The degree to
which the available control measures are implemented by.any yard
depends upon conditions prevailing at the facility, physical
constraints within the facility, economic factors, and, to a large
extent, management philosophy. r:ii c.
All facilities practice some degree of clean up at various times,
although this may consist only of moving debris out of the work area
when accumulations interfere with operations. During the docking
period, some facilities use extensive clean-up procedures, not only to
remove debris prior to flooding, but to eliminate possible contact
with gate leakage, hydrostatic water, or rainwater. In general
drydock clean up is directed toward improving productivity and safety
and toward maintaining acceptable working conditions. Both mechanical
and manual methods are in use.
81
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Mechanical clean-up methods used or tried include mechanical sweepers,
front loaders, vacuum equipment and closed cycle blasting. Manual
methods include shovels, brooms, and hoses.
Control of water flows within the dock, like clean-up procedures,
varies with facility. In some cases, no controls of wastewater from
either the docked vessel, industrial activities, leakage, or other
natural causes are practiced.
Other facilities use methods to control and segregate water flows or
have plans to implement such control. Generally, control and
segregation of water flows in the dock, when practiced, has been for
the same purposes as clean up, i.e., productivity, safety, and
improved working conditions. However, recently, particularly in naval
facilities, this form of control has the added purpose of eliminating
potential discharge of pollutants.
In summary the treatment and control technology being applied or
planned for drydocks consists of clean-up procedures and control and
segregation of water flows. The objectives of clean-up activities
are:
o To improve productivity by removing physical obstacles and
impediments to men and machinery working in the dock.
o To improve safety by eliminating hazardous materials and
conditions from the work area.
o To improve working conditions by eliminating health (and
safety) hazards and factors detrimental to morale.
o To prevent potential contaminants from being discharged to
the atmosphere or waterways.
Where control and segregation of water flows within the docks are in
use or planned the objectives are:
o To segregate sanitary waste, cooling water, industrial
wastewaters, and leakages in order to comply with existing
regulations governing sanitary wastes.
o To comply with existing regulations governing oil spills and
discharges.
o To prevent transport of solids to the waterway way and
contact of wastewater with debris in the drydock.
Management practices consistant with attaining these objectives have
been defined. These represent actions and philosophies which can be
82
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adopted in the normal course of shipyard operations. As such they can
be set forth in general terms, and the particular conditions
prevailing at each facility will determine the details and methods of
implementation. The best management practices are presented below.
The following specific requirements shall be incorporated in NPDES
permits and are to be used as guidance in the development of a
specific facility plan. Best Management Practices (BMP) numbered 2,
5, 7 and 10 should be considered on a case-by-case basis for yards in
which wet blasting to remove paint or dry abrasive blasting do not
occur, and BMP 10 does not apply to floating drydocks.
BEST MANAGEMENT PRACTICES (BMP)
BMP 1. Control of Large Solid Materials. Scrap metal, wood and
plastic, miscellaneous trash such as paper and glass,
industrial scrap and waste such as insulation, welding rods,
packaging, etc., shall be removed from the drydock floor
prior to flooding or sinking.
BMP 2. Control of Blasting Debris. Clean-up of spent paint and
abrasive shall be undertaken as part of the repair or
production activities to the degree technically feasible to
prevent its entry into drainage systems.. Mechanical clean-
up may be accomplished by mechanical sweepers, front
loaders, or innovative equipment. Manual methods include
the use of shovels and brooms.. Innovations and procedures
which improve the effectiveness of clean-up operations shall
be adapted, where they can be demonstrated as preventing the
discharge of solids. Those portions of the drydock floor
which are reasonably accessible shall be "scraped or broomed
clean" of spent abrasive prior to flooding.
After a vessel has been removed from the drydock and the
dock has been deflooded for repositioning of the keel and
bilge blocks, the remaining areas of the floor which were
previously inaccessible shall be cleaned by scraping or
broom cleaning prior to the introduction of another vessel
into the drydock. The requirement to clean the previously
inaccessible area shall be waived either in an emergency
situations or when another vessel is ready to be introduced
into the drydock within fifteen (15) hours. Where tides are
not a factor, this time shall be eight (8) hours.
BMP 3. Oil, Grease, and Fuel Spills. During the drydocked period
oil, grease, or fuel spills shall be prevented from reaching
drainage systems and from discharge with drainage water.
Cleanup shall be carried out promptly after an oil or grease
spill is detected.
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BMP 4. Paint and Solvent Spills. Paint and solvent spills shall be
treated as oil spills and segregated from discharge water.
Spills shall be contained until clean-up is complete.
Mixing of paint shall be carried out in locations and under
conditions such that spills shall be prevented from entering
drainage systems and discharging with the drainage water.
BMP 5. Abrasive Blasting Debris (Graving Docks). Abrasive blasting
debris in graving docks shall be prevented from discharge
with drainage water. Such blasting debris as deposits in
drainage channels shall be removed promptly and as
completely as is feasible. In some cases, covers can be
placed over drainage channels, trenches, and other drains in
graving docks to prevent entry of abrasive blasting debris.
BMP 6. Segregation of Waste Water Flows in Drydocks.. The various
process wastewater streams shall be segregated from sanitary
wastes. Gate and hydrostatic leakage may also require
segregation.
BMP 7. Contact Between Water and Debris. Shipboard cooling and
process water shall be directed so as to minimize contact
with spent abrasive and paint and other debris. Contact of
spent abrasive and paint by water can be reduced by proper
segregation and control of wastewater streams,. When debris
is present, hosing of the dock should be minimized. When
hosing is used as a removal method, appropriate methods
should be incorporated to prevent accumulation of debris in
drainage systems and to promptly remove it from such systems
to prevent its discharge with wastewater.
BMP 8. Maintenance of Gate Seals and Closure. Leakage through the
gate shall be minimized by repair and maintenance of the
sealing surfaces and proper seating of the gate.
Appropriate channelling of leakage water to the drainage
system should be accomplished in a manner that reduces
contact with debris.
BMP 9. Maintenance of Hoses, Soil Chutes, and Piping. Leaking
connections, -valves, pipes, hoses, and soil chutes carrying
either water or wastewater shall be replaced or repaired
immediately. Soil chute and hose connections to the vessel
and to receiving lines or containers shall be positive and
as leak free as practicable.
BMP 10. Water Blasting, Hvdroblasting, and Water-Cone Abrasive
Blasting (Graving Docks). When water blasting,
hydroblasting, or water-cone blasting is used in graving
docks to remove paint from surfaces, the resulting water and
-------
debris shall be collected in a sump or other suitable
device. This mixture then will be either delivered to
appropriate containers for removal and disposal or subjected
to treatment to concentrate the solids for disposal and
prepare the water for reuse or discharge.
CURRENT TREATMENT AND CONTROL TECHNOLOGIES
Most of the current efforts toward water pollution control in both
graving docks and floating drydocks are derived from the
recommendations of the rationale for shipbuilding and ship repair
facilities published by the Denver branch of EPA's National Field
Investigations Center in 1974, (Reference 2), after observing the
practices in effect in some shipyards. That document emphasized the
segregation of wastewaters and general housekeeping practices. It was
recommended that all water flows be intercepted or otherwise
controlled in order to prevent contact with spent paint and abrasive
and other solid materials on the drydock floor. Procedures for
handling particular water flows, cooling water, hydrostatic relief
water, gate leakage, and air scrubber water were specified.
Miscellaneous trash was to be eliminated through "the diligent use of
waste receptacles or a thorough clean up...prior to flooding." Clean
up of the drydock floor to "broom clean conditions" prior to each
undocking was recommended.
Many of the shipyards contacted or visited during the course of this
study have made efforts to comply with these recommendations. Their
efforts fall into two general areas (as set forth in Table VII-1):
o Clean up of abrasive
o Control of wastewater flows
The extent to which particular treatment and control technologies were
found to exist during the contact and visit phase of this study are
shown in Table VII-2.
The following paragraphs describe observed sequences of the drydock
treatment and control technologies listed in Table VII-3. It should
be noted that certain of these processes and technologies are designed
to reduce or eliminate effluents in drainage pump discharges and
overboard flows from floating drydocks. Others are effective on the
much larger discharges which occur during deflooding and sinking. The
next few pages document procedures for the clean-up of spent abrasive
and other solid drydock debris at seven shipyards which were visited
and observed (labeled shipyards A through G) as well as procedures for
handling cooling water discharges.
85
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Table VII-1. WATER QUALITY TREATMENT ANC CONTPOL
TECHNOLOGIES CURRENTLY BEING USED IN DRYDOCKS
Purpose
Clean-up of Abrasive
From Drydock Floor
From Drainage Trenches
Control of Wastewater
Flows
Technology
Front Loader
Hand Shovel and Broom
Eackhoe
Hand Shovel
sill. Channeling, or
Trench Drain for
Control of Gate Leakage
and Hydrostatic Relief
Pollutants Possibly
Affected Applicability
FLO, SUS, SET, HM
FLO, SUS, SET, HM
FLO, SUS, SET, HM
FLO, SUS, SET, HM
FLO, SUS, SET, HM, O
GD, FD
GD, FD
GD
GD
FLO « Floating Solids
SUS = Suspended solids
SET * 5ett.lable Solids
O * Oil and Grease
HM « Heavy Metals and Other Chemical Constituents
pH = pH
Air = particulates
SOLIDS - Solid waste
GD = Gravinq Dock
FD = Floating Drydock
86
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Table VII-2. WATER QUALITY TREATMENT AND CONTROL
TECHNOLOGIES UNDER DEVEtOPMENT CR NOT B.EING USED IN DRYDOCKS
Purpose
Technology
Clean-up of Abrasive
From Drydock Floor Mechanical Sweeper
From Drydock Floor Vacuuir Recovery
or Drainage Trenches Equipment (Sta-
ipnary or Mobile)
Alternative To
Conventional Dry
Abrasive Blasting
control of Wastewater
Flows
Water Cone Abrasive
Blasting
Wet Abrasive Blasting
Hydroblasting (Steady
Streair or Cavitation)
Closed-Cycle Abrasive
Blast and Recovery
Cyclone Separation
and Cheirical-Physical
Pretreatirent
Channeling for Improved
Fleer Crainaqe
Curbing 6 Channeling
on Floating Drydccks
Scrupper Boxes, Hose,
Piping, and/cr Pumps
for Clean Water
Discharges
Cover Plates to Prevent
Abrasive frcir Entering
Drainage System
Containment, cf Flews
frcir Wet Blasting
Baffle Arrangement for
settling in the Drainage
System
Contained Absorbent
in Discharge Flew Path
wire Wesh in Discharge
Flew Path
Adaptation of Pcntccns
for Settling Solids
Flat Floor Overlay
Removal of Bilge
Block Slides
Increased Keel Blcck
Clearance
Hydraulic Bilge Blocks
i; = Sewage O = Oil and Grease
rLO = Floating Solids HM = Heavy Metals and
3US = Suspended Solids Other Constituents
3FT = Settleable Solids pH = pH
Treatment of Waste-
water Flows
Access for Clean-up
Operations,
Pollutants Intended
To Be Affected
FLOW, SET, SOS, HM
FLO, SET, SDS, HM
MR
AIR
Applicability
GD, *»
GD, FD
GD, FD
GD, FD
AIR, SET, SUS, HM, SOLIDS GD, FD
AIR, SET, SUS, HM, SOLIDS GD, FD
AIR, SET, SUS, HM, SCLIDS GD, FD
pH
SET, SUS, HM, O GD
SET, SUS, HM, O FD
SET, SUS, HM, O GD, FD
SET, SUS, HM GD
SET, SUS, HM, O . GD, FD
SET, SUS GD
O GD
FLO GD
SET, SUS, O FD
FLOW, SET, SUS, HM GD, FD
FLO, SFT, SUS, HM GD, FD
FLO, SET, SUS, HM GD, FD
FLO, SET, SUS, HM GD, FD
FLO, SET, SUS, HM GD, FD
AIR = Particulates
GD = Graving Docks '
FD = Floating Drydocks
SCLIDS = Solid Waste
87
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'.Cable VII-3. REPORTED APPLICATION OF THE TREATMENT AND CONTROL TECHNOLOGIES
Shipyards Visited
Purpose
Clcan-Up of
Abrasive From
DrydocX Floor
From Drainage
Ditches
Alternative to
Conventional Dry
Abrasive Blasting
Control of Waste-
water flows
Technology
Front Loader
Mechanical Sweeper
Hand Shovel
Broom
Vacuum Recovery Equipment
Backhoe
Hand Shovel
Vacuum Recovery Equipment
Container Lifted by Crane
Water Cone Abrasive
Blasting
Wet Abrasive Blasting
Hydroblasting
Steady Stream
Cavitation
Closed Cycle Abrasive
Blast and Recovery
Cyclone Separation
Chemical-Physical
Pretreatment
Sill/ Channeling/ or Trench
Drain for Control of Gate
A
X
X
X
X
*
X
X
X
X
X
X
X
X
B
X
X
X
X
*
X
X
X
X
X
X
X
X
C
*
X
X
NA
NA
NA
NA
X
X
X
X
X
X
D
X
*
Z
X
*'
Z
X
*
*
X
X
Z
X
E
*
*
X
X
*
X
X
X
*
X
X
X
Z
F
X
X
X
X
X
*
*
X
*
X
X
X
X
X
X
G
*
X
*
X
X
NA
NA
NA
NA
X
X
X
X
Z
X
NA
Leakage and Hydrostatic Relief
Treatment of
Wastcwater Flows
Channeling for Improved
Floor Drainage
Curbing and Channeling of
Floating Drydocks
Scupper Boxes/ Hose/ Piping/
and Pumps for Clean Water
Discharges
Cover Plates to Prevent
Abrasive from Entering
Drainage System
Containment of Floor from
Wet Blasting
Baffle Arrangement for
Settling in the Drainage
System
Contained Absorbent in
Drainage Discharge Flow Path
Wire Mesh in Drainage
Discharge Flow Path
Adaptation of Pontoons for
Settling Solids
X
X
X
X
X
X
X
X
X
NA
X
NA
Z
X
X
NA
X
X
NA
NA
NA
NA
NA
X
*
X
X
X
X
X
X
X
X
NA
*
*
X
X
NA
NA
X
NA
X
X
X
X
X
NA
NA NA
X
NA
NA
NA
NA
NA
X
Shipyards Contacted (H Through AI
Insufficient
Use Do Not Use Information
21
1
26
5
2
0
0
0
0
0
0
3
0
1
7
27
1
20
26
.,0
0
0
0
4
0
28
2
2
3
5
2
30
30
30
30
30
26
23
30
1
30
30
30
30
21
30
30
30
30
30
30
Use
X - Do Not Use
2 » Planned/ Infrequent Use, or Under Development
NA- Not Applicable
88
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Most of the facilities visited perform a manual pick up of large
debris prior to each undocking. Such debris includes scrap metal,
large wood chips or blocks, metal cans, scrap paper, paint cans, and
the like. After this manual pick up, with the aid of shovels, the
debris is deposited into receptacles on the drydock floor for removal
and disposal. Some shipyards require this procedure at the end of
each shift. Upon completion of this phase, only spent abrasive and
other small sized debris remain on the drydock floor. A variety of
procedures and technologies to remove the remaining substances were
observed.
At many shipyards, no efforts are made to remove spent abrasive from
the drydock floor prior to flooding. Docks servicing fresh water
vessels rarely do any extensive blasting and consequently do not have
spent abrasive to collect. In some cases contractual requirements do
not allow time for clean up. Some companies regard the clean up
process as difficult, time-consuming, labor-intensive, and hence
expensive. The practice of no clean up was observed in smaller or
older drydocks, particularly those with raised bilge block slides and
those not requiring keel or bilge block movement prior to the next
docking. The necessity for clean up is perceived at these docks only
when accumulations of spent abrasive reach such levels that it
interferes with keel or bilge block placement or movement, creates
hazardous working conditions, or reduces productivity. Those
conditions may be reached after only a few ships have been serviced or
after many. Clean up may be as frequent as weekly or as infrequent as
semiannually.
When clean up is necessary, front loaders are usually placed on the
drydock floor. With graving docks, cranes are required to lower the
machinery into the dock basin. The front loader is often modified to
permit access to the floor beneath the ships hull and consequently to
operate while the ship is still in dock. The loaders scrape and push
the spent abrasive into piles. Men with shovels and the front loaders
then place the accumulated waste in containers or hoppers.
When bilge block slides are present or low keel blocks are employed,
the efficiency of operation of the front loaders is greatly reduced.
The equipment has difficulty in passing over bilge block slides.
Frequent stopping and starting, climbing and falling wears down the
equipment and is time consuming. Laborers with shovels must manually
clean areas inacessible to the front loader, such as beneath the hull
and around the blocks and slides.
To remove the remaining grit some shipyards use manual sweepers.
Workers with push brooms sweep the abrasive into piles which are
transferred to the hoppers.
89
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In a few instances mechanical sweepers are also used., One sweeper, a
modified 1-3/4 ton truck, employs horizontal and vertical rotary
brushes to loosen and pick up spent abrasive and other debris from the
floor. These wastes are collected inside the sweeper. The sweeper
can make two passes along the length of the dock before becoming full;
then it must be emptied before continuing. The sweeper dumps its
contents in a pile on the floor of the drydock. The pile is then
loaded into containers by front loaders and laborers with shovels. --
*.,'.* > * -f*V
The mechanical sweeper has no arrangements for reaching around or
under obstructions. It is also too high to clean under ships and can
only clean those areas over which it passes. The sweeper cannot
operate effectively unless the floor is clear of removable
obstructions such as scupper hoses, hoppers of abrasive, scaffolding,
and materials being used in the drydock (paint cans, metal plates,
etc.). Thus, the sweeper does not begin clean up until after exterior
work on the hull has been completed. When a large ship has been
docked, there is little clearance along the sides or at the end of the
dock. In such cases, space does not allow for the sweeper to be used
prior to undocking. "'"'-"'
Shipyard A has two graving docks and three floating drydocks It
utilizes scupper boxes and hoses to direct cooling water discharges
from the vessel to the drydock drains and ultimately to the harbor.
Graving dock caisson leaks are intercepted at the outboard end of the
dock and pumped back to the harbor without coming into contact with
solid wastes on the floor of the graving dock. Hydrostatic leakage
flows to drainage trenches along the periphery of the floor and is
pumped to the harbor. The wastes are invariably wet and packed from
flooding or sinking of the dock, from rain, and from the movement and
placement of equipment, men and materials. This makes the drydock
floor at Shipyard A difficult to clean thoroughly. Also, Shipyard A
drydocks have bilge block slides that are raised above the dock
surface and interfere with cleaning operations.
Clean up occurs whenever abrasive buildup has reached a depth such
that the bilge blocks can no longer be repositioned on the bilge
slides. This is necessary following approximately five dockings. When
clean up is necessary, front loaders are brought in to scoop and
scrape the drydock floor. Wastes are accumulated in piles, then
collected in containers using front loaders and shovels. The
containers are lifted out of the drydock by cranes and placed onto or
emptied into trucks. Laborers with hand shovels accompany the front
loaders, primarily under the hull and at the bilge blocks and their
slides. -
Shipyard B has five graving docks and cleans up spent abrasive and
related debris prior to each undocking. The clean up procedure of
Shipyard B is identical to that of Shipyard A except that it is
90
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performed more frequently. As the time for undocking approaches,
front loaders and laborers with shovels clean the floor. In Shipyard
B, the wastes are frequently dry. Shipyard B has no raised bilge
block slides. Thus, the clean up at Shipyard B is ordinarily less
time consuming per occurrence than the clean up at Shipyard A.
Shipyard B uses scupper boxes and hoses to direct cooling water
discharges to the drydock drains. The hoses observed, however, were
in poor shape and considerable leakage flowed across the drydock
floor. The discharges are pumped from the drains to the .harbor.
Caisson leakage is intercepted at the outboard end of the docks and
pumped to the harbor. Hydrostatic relief and leakage waters flow to
trenches along the periphery of the dock and are pumped to the harbor.
Shipyard C has two flush decked floating drydocks and also cleans
prior to and after each undocking. The cleaning is performed using a
mechanical sweeper and a front loader. The sweeper and front loader
are utilized to clean as best as practicable before flooding.
Following flooding and undocking of the vessel, the sweeper and front
loader are returned to the dock and work unimpeded (except for the
keel blocks and bilge blocks) and effect a complete cleaning
operation. In every case, the sweeper completes its clean up
including areas previously inaccessible subsequent to flooding,
undocking, and deflooding but before the docking of the next vessel.
Shipyard D has three graving docks and two floating drydocks. Clean
up of spent abrasive and associated debris is performed on a
continuing basis. Upon completion of a blasting operation, front
loaders and shovels are brought in to collect the wastes into piles
and then load them into containers. This operation may occur several
times during a single docking depending on the scheduling of abrasive
blasting. Following the use of front loaders and shovels, laborers
use push brooms to sweep the docks. Just before undocking, the front
loaders, shovels, and brooms are returned to the drydock floor for a
final comprehensive clean up. On occasion, remaining wastes are hosed
to the drainage system. The drainage system and the flooding tunnel
are shovelled out on an as-required basis, but not necessarily prior
to each undocking. Scupper boxes arid hoses are attached to the vessel
in drydock to direct cooling waters to drains discharging to the
harbor. Hydrostatic leakage water and water from internal tank
blasting units flow across the drydock floor to overboard drains where
they are pumped to the harbor.
Shipyard E has one graving dock. The clean up at Shipyard E begins
with front loaders and shovels. The shovellers accompany the front
loaders in addition to cleaning those areas the front loaders cannot
reach or cannot clean effectively, such as at corners and surfaces or
between bilge blocks. Wastes are consolidated into piles before being
loaded into containers. A mechanical sweeper follows the front
loaders and shovels. The sweeper works like the sweeper at Shipyard
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C« If these procedures do not result in a satisfactory floor
condition, shovels and push brooms are used to complete the job.
Flooding ports in the dock floor are shovelled out prior to each
undocking. The flooding tunnel is inspected and shovelled out if
necessary. Stairways are swept manually, as are the utility dugouts
and the altar. Areas adjacent to the dock are cleaned by a small,
mobile, mechanical sweeper the size of a small front loader. No
hosing of abrasive is performed at Shipyard E during the clean up
prior to undocking. Clean up of abrasive and debris occurs for each
ship at the end of its stay in the drydock, not on an ongoing basis as
is the practice at Shipyard D. Scupper boxes and hoses are attached
to the vessel after drydocking to direct cooling water discharges to
drains to the harbor. The graving dock was dry with no evidence of
hydrostatic relief or leakage water in the dock during the visit to
this shipyard. ' =.,^-. .
All of the shipyards described up to this point service primarily
saltwater ships which require high levels of abrasive blasting. Some
shipyards service only freshwater ships. Clean-up procedures and
technologies at these yards are correspondingly different.
Shipyard F has two graving docks and services vessels that sail in
fresh (inland) waters. This facility does very little abrasive
blasting. Ships at this yard receive no abrasive blast treatment at
all to remove paints. Shipyard F has no mechanized equipment for the
removal of spent abrasive and other granular debris. It performs no
clean up of such materials prior to undocking. Large debris is picked
up manually. After flooding, undocking, and the subsequent
deflooding, material accumulated on the drydock floor (which at this
point includes silt and other debris which entered during flooding) is
hosed to the drainage trenches. Hosing of the dock floor is carried
out in order to maintain clean working conditions and to improve
productivity. Therefore, the clean up is not always complete,
especially at the ends of the dock, near the drainage trenches and
away from working or dock entry areas. Little hosing is done on minor
accumulations around the keel blocks or bilge blocks if no block
movement is necessary. Periodically (every few months), the trenches
fill and require cleaning. All drainage water from the graving docks
is pumped into a sluice. A floating box containing an absorbent for
oil and grease completely blocks the discharge end of the sluice.
Water can flow under (the box extends only a short distance below the
surface) and through the box, but floating oil and grease are removed
by the absorbent.
All vessels are evacuated and shut down during drydocking;
consequently, little or no water of any type is discharged to the
graving docks during the servicing period. Caisson leaks and
hydrostatic relief or leakage waters are collected in trenches and
pumped through the sluice to the harbor.
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Shipyard G has two floating drydocks. During ship repair on one of
the floating drydocks (a flush deck dock), spent abrasive is
consolidated into piles using front loaders and shovels. The piles
are loaded into containers for disposal. This activity begins soon
after abrasive blast operations have ended regardless of the remaining
period for the ship to be in dock. Shipyard 6 does more abrasive
blasting than Shipyard F, but rarely at levels comparable to the
saltwater shipyards A, B, C, D, and E. Normally, the crew does not
remain on board during drydocking at Shipyard G. Since shipboard
services are shut down there are no cooling water discharges. -On the
second floating drydock (having bilge block slides on deck), spent
paint and abrasive is cleaned up only when accumulations interfere
with vessel repair operations or cause safety hazards. This occurs
about twice a year. The vessel is evacuated during drydocking;
consequently, there are no discharges from the ship.
CONTROL AND TREATMENT OF WASTEWATER FLOWS
In addition to clean up of solid wastes from the drydock floor,
efforts to control and treat wastewater flows are being undertaken at
many facilities. In the dewatered graving dock there are two streams
of wastewater during ship repair operations: (1) cooling and process
wastewater discharges, and (2) flows from various sources such as
caisson leaks, hydrostatic relief or leakage, and industrial or
process wastewater. Floating drydocks also have these wastewaters,
with the exception of caisson and hydrostatic leaks. Process
wastewaters include discharges from air scrubbers, wet grit blasting,
and tank and bilge cleaning. Tank and bilge cleaning wastes are oil
and water mixtures. A collection and holding tank system, usually the
Wheeler (TM) type, is used to remove and separate this waste. Other
wastewaters may be directed by hoses or allowed to flow across the
floor into the graving dock drainage system, or directly to ambient
waters from floating drydock pontoon decks. Miscellaneous water flows
come from such sources as hydrostatic relief, non-contact cooling
discharges, gate leakage, and pipe and fitting leakage. Existing dock
drainage system designs allow process wastewaters to mix with other
wastewater. They may contact solid wastes on the deck or in the
trench before being discharged into ambient waters. -
The volume of wastewater discharged from a ship in drydock may depend
upon the point in the docking cycle. As shipboard equipment which
uses water is being shut down following docking, the volume of
discharge decreases. The continuing volume of discharge from the ship
will depend upon the size of the crew remaining on board while in
drydock. Some ship operators, such as the U.S. Navy, keep most of the
operating crew on board even when the ship is drydocked for an
extended period. This practice generates considerable volumes of
wastewater. Other operators may shut down all equipment and remove
the entire crew even for short drydocking periods.
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Another factor bearing on the volume of water passing through a
drydock is the effectiveness and level of maintenance effort applied
by shipyard facility personnel to the many fittings and valves in the
drydock potable and nonpotable water systems. Industrial water usage
is minimal and higher flows occur only if wet abrasive blasting, water
cone blasting, or hydroblasting is used. The use of hoses for clean
up also contributes to wastewater volume. Drydock industrial waters
are sometimes controlled by channels, sills, and drainage trenches.
Some graving docks have arrangements for interctjpting flows and
conducting the water to drainage systems. This reduces contact of
gate leakage and hydrostatic relief water solids on the drydock floor.
Floating drydocks, on the other hand, generally lack arrangements for
the containment of flows, and have no hydrostatic or gate leakage.
Graving dock drainage system designs vary widely but all involve
networks of gutters, trenches, and/or culverts which serve to collect
the heavier settleable solids transported in industrial wastewater
flows. Unless promptly removed this debris may come in contact with
water flows. To protect drainage pumps from excessive wear or damage,
some drainage systems are designed with settling basins or sand traps
to intercept and settle even the lighter particles. This removes
transported particles from the discharge flow but may increase contact
of water with solid wastes. Some of these settling locations, such as
shallow transverse and longitudinal gutters in the drydock floor are
relatively easy to clean out. Large longitudinal drainage culverts
under the walls of graving docks can be extremely difficult to clean.
TREATMENT AND CONTROL TECHNOLOGIES UNDER DEVELOPMENT OR NOT IN COMMON
USE
Many technologies are being developed that potentially can reduce
solid waste, expedite clean up and control wastewater flows. In the
section on "Control or Clean Up of Abrasive Through Access In Clean Up
Operations11 these technologies are discussed. The second half of Table
VII-1 has summarized these developmental projects-
Control or Clean Up of Abrasive
High-suction vacuum grit removal equipment, such as the Vacu-Veyor
(TM) unit, is used extensively to collect and remove debris from
blasting operations in the ship*s interior. Occasionally, however,
the situation accommodates placing a container directly beneath an
access hole cut through the ship's side, to collect the debris
directly. Several existing kinds of equipment, not originally
designed for drydock use, are being evaluated and modified to
facilitate the removal of spent abrasive and debris. Vacu-Veyor (TM)
units are relatively simple devices which are used in removing dry
abrasive and debris from internal tank blasting operations and
occasionally from drydock floors. They suffer, however, from a lack
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of mobility and the airborne particulate material cannot be
effectively contained when blown into open skip boxes (Reference 9).
At least one shipyard is attempting to develop this equipment by
enclosing the container and making the unit more easily moveable. Two
other complex, high-suction vacuum machines are being evaluated and
developed by shipyard facilities. They are the VAC-ALL (TM)
(References 8r 9, & 12) and the VACTOR 700 (TM) (References 6 & 8)
units. Both of these units have demonstrated tremendous capability to
move large amounts of grit in a relatively short time but both, in
their present configuration, have many limitations for drydock
application. A third type of vacuum equipment being evaluated for use
in removing grit and debris from drydock floors is a low profile self-
propelled device called the ULTRA-VAC (TM) Grit.Vacuum. It shows the
most promise for application in flush floored drydocks and can best
be described as a powerful vacuum cleaner on wheels (References 8, 9,
& 12). Until a design evolves from the development of these three
types of vacuum equipment that will meet the needs of the varying
drydock characteristics, most facilities will be forced to resort to
labor intensive, time consuming techniques to remove debris.
Alternatives to conventional dry abrasive blasting include water cone
abrasive blasting, wet abrasive blasting, hydroblasting (steady stream
or cavitation), and closed cycle abrasive blast and recovery. Some of
these techniques have potential for reducing or eliminating the
quantity of solids required in blasting but some substitute a water
pollution problem for an air pollution problem. None of these
technologies can completely replace conventional dry abrasive blasting
and all are in various stages of development.. Table VII-2 indicates
which shipyards contacted are currently practicing these alternatives.
A variation of the wet grit method of abrasive blasting* called water
cone, water envelopment, or water ring, is fairly new but rapidly
gaining popularity particularly with increasing use of organotin
antifouling paints on some Navy ships- This process projects a cone
of water around the stream of air and abrasive as it leaves the hose
nozzle. This is accomplished by a simple water ring accessory which
fits around any standard blasting hose nozzle. This method has the
advantages of dry grit blasting with less dust production. It does,
however, add to the volume of industrial wastewater and rust
inhibitors, when added, are present in the wastewaters (References 7
and 9) .
Hydroblasting is a surface preparation method used when extensive,
heavy abrading is not a requirement. In one technique a cavitating
water jet is used as the abrading material. As explained in Reference
13:
"The basic concept simply consists of inducing the growth of
vapor-filled cavities within a relatively low velocity liquid
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jet. By proper adjustment of the distance between the nozzle and
the surface to be fragmented, these cavities are permitted to
grow from the point of formation, and then ibo collapse on that
surface in the high pressure stagnation region where the jet
impacts the solid material. Because the collapse energy is
concentrated over many, very small areas at collapse, extremely
high, very localized stresses are produced. This local
amplification of pressure provides the cavitating water jet with
a great advantage over a steady non-cavitatiing jet operating at
the same pump pressure and flow rate."
,'' - vs. j**»
Considerable success in laboratory experiments is claimed for the
CAVIJET (TM) method but results of field evaluation are not available.
Several versions of closed-cycle vacuum abrasive blasting equipment
are undergoing engineering development and operational evaluation at
various shipyard facilities. They all operate on the principle of
automatically recovering and reusing abrasives. Abraded coatings and
fouling are sometimes separated and contained for land disposal. The
machines, when operating as designed, are expected to eliminate both
air and water pollution problems resulting from dust emissions and
from solid wastes entering the drydock drainage system. If steel shot
is used as the abrasive and is recovered, the solid waste load is
reduced many times. Steel shot retains its cutting power even after
repeated reuse. The closed-cycle blaster has limits however. These
machines will not completely supplant other surface preparation
techniques since they are large, heavy, and require considerable space
for maneuvering. In addition, they are not designed to function on
other than nearly flat or gently curving surfaces. More detailed
information regarding come of these machines is provided in technical
references to this document, particularly those prepared by or for the
U.S. Navy.
Control of Wastewater Flow !i «*>>
The control and treatment of wastewater flows is critically tied to
the segregation of wastewater streams. This philosophy is best
expressed in a quote from Reference 6:
"The key to cessation of unnecessary liquid waste generation...is
seen as segregation of wastes as completely as possible and
reasonable. Unpolluted waters should be segregated from
contaminated solid wastes and vice versa.
An appropriate system to collect and convey liquid waste must be
capable of maintaining segregation until contaminated wastes are
removed from the drydock and unpolluted wastes are properly
discharged to harbor receiving waters."
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This report proceeds with definitions of systems and techniques to
segregate, collect, and transfer contaminated and uncontaminated
wastewater streams (and materials causing contamination) to
environmentally acceptable treatment systems.
A similar philosophy of approach was reported in Reference 11;
"A practical solution to eliminate the large volume of polluted
wastewater discharge into the harbor would be segregation of
clean water flows from both spent abrasive and any already
polluted wastewaters. This is the basis for the following
recommendations. wastewaters can be divided into three streams.
The first stream, comprised of hydrostatic water, ships* cooling
water, and miscellaneous other equipment cooling water
discharges, could be collected in what will be henceforth called
the clean water conduit. These unpolluted waters could be
discharged directly into the harbor without treatment. The
second stream, comprised of drydock sanitary wastewater and
ships* non-oily wastewater, could be collected in a sanitary
sewer and pumped to a municipal sewage treatment plant. The
third stream, comprising all other wastewater discharges
including ships1 oily wastewater, dock floor wash water,
miscellaneous equipment washings, spills, sewer leaks, rain, and
clean water which accidentally contacts the dock floor, could be
collected in an industrial wastewater sewer and pumped to an
industrial wastewater treatment facility."
The facility that served as a model for these two studies is planning
the implementation of the recommended improvements.
Segregation of water flows is accomplished by physical isolation.
Collection can be through either or both in-floor and above-floor
plumbing systems. For example, above-floor systems can be fabricated
from PVC piping and attached adjacent to keel blocks.
Treatment of Wastewater Flows
Innovative controls will be installed at one shipyard in its graving
docks having large transverse trenches or cross drains near the
outboard or drain end. Involved is an arrangement of baffles in the
cross drain as a means of minimizing the discharge of settleable
solids and floating material. The baffles will be installed so as to
use the cross drain as a settling pond. A baffle acts as a dam to
establish a water level and hence a retention time for settleable
solids to separate. Water flowing over the top of this baffle will go
directly to the drainage pump. Upstream of this overflow dam, a
second baffle will be installed to form an underflow dam for holding
floating debris, oil, or other substances for collection and ^removal
prior to flooding the drydock. Both baffles will be removable, and
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provisions will be made to drain off the water held behind them.
Settleable solids contained within the cross trench will be removed
for land disposal. The baffles will be installed after the ship is
secure in the dock and the initial dewatering has been completed. The
installation will not minimize the contact of solids with water
streams, but is expected to .reduce the potential of solids transport.
At one facility (Shipyard F), graving dock discharges, other than
dewatering, are directed through a flume prior to emission to the
adjacent river. Across this flume, near the discharge end, a floating
box-like structure is placed in the flume after dewatering. The box-
like structure holds a screen across the surface of the flow to
prevent floating trash and debris from entering ambient waters. It is
filled with absorbent material which removes oil and grease from the
discharge flow. The absorbent material is replaced as needed.
Access In Clean-Up Operations
Two items of drydock design make efforts to clean up industrial
wastes, such as abrasive blasting debris, more difficult and costly.
They are the height of keel blocks and the existence of raised slides
across the floor (or pontoon deck) for movement of bilge blocks.
Almost all existing drydocks have keel block heights of 3-1/2 to 6
feet. Older docks tend to have smaller keel blocks. With short keel
blocks the working space between the drydock deck and ship bottom is
too restricted for men using shovels and brooms to effectively clean
up blasting debris and for using mechanized techniques currently
available. This situation is most severe when the ship has a wide
beam and a flat bottom. At least one new graving dock, currently
under construction, will have 10-foot high keel blocks.
Graving docks and floating drydocks which have bilge block slides
present a particularly severe problem to clean-up activities.
These solids establish corners and crevices from which fine debris is
difficult to remove. They interfere with the movement of wheeled
equipment and increase maintenance costs of the equipment used to
clean up blasting debris (such as small front loaders). The
positioning of these tracks across the flow direction of launch water
may be beneficial, however, in acting as a submerged weir or dam,
trapping sediment that would otherwise wash away.
NON-WATER QUALITY ENVIRONMENTAL ASPECTS
The control and treatment technologies described in this section are
designed to improve the water quality of drydock discharges. However,
some of these technologies also impact, either favorably or
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unfavorably, on other environmental concerns, particularly air
pollution and solid waste. This subsection addresses those impacts.
Air Pollution Several control technologies provide alternatives to
conventional dry abrasive blasting. These alternatives include wet
abrasive blasting, hydroblasting using either steady stream or
cavitation, water cone abrasive blasting, closed cycle abrasive blast
and recovery equipment, and chemical stripping. Comparison of these
alternatives must include many considerations among which are the
desirability and thoroughness of surface preparation, speed of
application, labor costs, equipment modifications, capital required,
occupational health and safety, and effects of possible contamination
of water flows. However, all of the alternatives are extremely
effective in the reduction or elimination .of one of the most
detrimental aspects associated with dry abrasive blasting, namely . the
production of airborne particulates.
Upon impact, abrasive particles fracture. The larger fragments fall
to the drydock floor or occasionally to adjacent land or water areas.
Smaller fragments, however, become airborne or suspended, along with
some particles released from the blasted surface. Depending on the
wind, they may travel appreciable distances. Shifting to harder blast
media reduces these effects only slightly.
Most of the technologies listed above have been developed more as air
pollution control measures than water pollution control measures..
Closed-cycle abrasive blast and recovery equipment uses a vacuum to
pull blast particles from the air as they are released. This
equipment (of which there are several types in various stages of
development) is not totally successful in the recovery of blast
particles; however, the characteristic plume of 3ust emanating from
dry abrasive blasting is eliminated and the level of airborne
particulates and suspended solids is drastically reduced. Wet
abrasive blasting and water cone abrasive blasting prevent the
production of airborne particles by wetting blast fragments. The
moisture-laden fragments then fall to the drydock floor or drip down
the structure being blasted. Wet abrasive blasting is a particularly
effective means of improving air quality in blasting. Water cone
abrasive blasting, though not as effective, still reduces the air
pollution problem to a local one involving only the blast nozzle
operator and those in the immediate vicinity. Hydroblasting preempts
the problem of abrasive fragmentation by eliminating the source, i.e.,
the abrasive. Only particles from the surface being blasted must be
contended with and in hydroblasting, these particles are.wet, causing
virtually all to drop. Chemical stripping completely eliminates
airborne particulates since it involves no blasting. Chemicals are
brushed on, allowed to work, then scraped off manually. Because slow,
labor-intensive methods are required, chemical stripping is used very
little. This technology trades off particulate emission for
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hydrocarbons and other chemical vapors caused by its high volatility.
Closed-cycle blasters under development which use steel shot show
promise of eliminating essentially all air and water pollution from
blasting operations.
Vacuum material handling equipment can be a source of particulate
emission where open collection containers are used. The magnitude of
this emission depends on the geometry of the collection system, the
volume and rate of material being moved, and the material composition,
particularly its moisture content and particle weight. Vacuum
equipment is ordinarily diesel powered and thereby contributes
hydrocarbons, nitrogen oxides, carbon monoxide, and other emissions
associated with diesel engine combustion. Mobile units have greater
fossil fuel energy requirements than stationary units and thus produce
higher levels of air pollution.
A number of the control technologies similarly affect air quality
through requirements for power from local combustion equipment.
Mobile sweepers and front loaders are examples. Pumping equipment on
mobile floating drydocks are usually diesel powered, so that drydock
design changes which result in the installation of pumping equipment
may add to air emissions. Such design changes include modifying
floating drydock pontoons for use as settling tanks, adding filtration
equipment or extensive new piping, and other efforts to segregate
wastewater flows which require additional pumping. Air emissions may
not increase if the pumping requirements are split without increasing
input energy requirements. Hydroblasting, by avoiding air as a
propellant, reduces air emissions from local air compressor stations.
This reduction occurs at the expense of emissions from the alternate
compression source. The practice of shutting down shipboard equipment
while in drydock also reduces air emissions, in this case, from fossil
fueled equipment on board.
Solid Waste
Conventional dry abrasive blasting creates appreciable accumulations
of solid waste. Where it is applicable, closed-cycle blast and
recovery equipment can greatly reduce the quantity of abrasive
required and alleviate the clean up of spent paint and abrasive.
Disposal of the material, whether from open or closed-cycle blasting
is required. Generally, solid wastes will be transported by a
contractor to landfill disposal sites.. Though the degree to which the
wastes are potentially harmful has not been assessed, several
considerations appear warranted. In order to ensure long-term
protection of the environment from potentially harmful constituents,
special considerations of disposal sites should be made. Landfill
sites should be selected which prevent horizontal and vertical
migration of constituents to ground or surface waters. In cases where
geologic conditions are not suitable adequate mechanical precautions
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(e.g., impervious liners) may be required to ensure long-term
protection of the environment. A program of routine periodic sampling
and analysis of leachates may be advisable. Where appropriate, the
location of solid hazardous materials disposal sites, if any, should
be permanently recorded in the appropriate office of legal
jurisdiction.
Of particular concern is the disposal of the new organotin wastes.
These toxic compounds which are sometimes used in antifouling paints
may be present in the spent paint, as well as originating from paint
spills and overspray. Currently the Navy, for example, requires that
these wastes be sealed in drums and shipped to a properly managed
landfill. These precautions are taken to prevent runoff, seepage, and
possibly leaching of organotin compounds. -
Other Environmental Aspects
In addition to air pollution and solid waste, some of the water
control and treatment technologies exhibit minor effects in other
environmental areas. The shut down of shipboard services reduces
cooling water discharges and consequent thermal pollution. Noise is
also reduced. Alternative technologies to dry abrasive blasting which
do not employ air as a propellant (hydroblasting and wet abrasive
blasting) reduce the load on shore-based air compressors and less heat
is added to the water. Thermal discharges from this source are thus
reduced. Vacuum material handling equipment and other engine-driven
equipment (closed cycle abrasive blast and recovery equipment, mobile
sweepers, front loaders, etc.) add to the general noise level in the
drydocks.
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SECTION VIII
COST OF TREATMENT AND CONTROL TECHNOLOGY
INTRODUCTION
The economics of currently applied treatment and control technology
were obtained during shipyard visits. The technologies, as listed in
Section VII, include:
o Technologies for the clean up of abrasive
o Alternatives to conventional dry abrasive blasting
o Control technologies for wastewater flows excluding sewage
o Treatment technologies for wastewater flows excluding sewage
The costs of clean-up and best management practices were developed
from information obtained during visits to shipyards A through G«
These represent a composite of costs for these seven facilities, and
are not specific to any one of them. This information was obtained
during the period March through May of 1976 and has not been adjusted
for inflation occurring since that period.
The reported and observed application of these technologies appears in
Table VII-2. Clean up of abrasive is practiced at each of the
shipyards visited and has been for many years. Much cost information
is available concerning technology for the clean up of abrasive. With
the exception of scupper boxes and piping, and design features for the
control of gate leakage and hydrostatic relief water, the other
treatment and control technologies have found little application among
the shipyards visited. Many of these technologies are in the
planning, research, or experimental stages of development and could
not be evaluated with respect to economics since actual cost data
(particularly operation and maintenance costs) are unavailable. The
cost data applies to current technologies for the clean up of abrasive
as reported and observed during the shipyard visit program.
Developmental methods are not considered.
Throughout the history of conventional dry abrasive blasting, it has
been necessary for shipyards which use appreciable amounts of abrasive
in their docks to clean it up periodically solely to continue in
business. Abrasive on the drydock floor can adversely affect working
conditions and productivity. It can hamper the placement and movement
of bilge blocks. It hampers the movement of mechanized equipment.
Consequently, shipyards have performed periodic clean up of abrasive
from the drydock floor. However, in 1974, the EPA, through its
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National Field Investigations Center in Denver, Colorado, recommended
that shipyards increase their efforts to prevent wastewaters from
contacting abrasive on the drydock floor and to clean up to "broom
clean" conditions prior to flooding or sinking.
Response to EPA's recommendations has been mixed. It is very
difficult to segregate clean-up costs for environmental purposes at
these shipyards and those costs which would have been incurred during
the normal course of business. The estimated costs developed here
reflect stepped up efforts to reduce effluent discharges to nearby
water bodies. But no effort is made to isolate the cost of these
stepped up efforts. Costs presented later in this section are total
costs of clean-up operations as currently performed.
The cost data include capital, labor, operating, and maintenance costs
incurred directly during clean-up operations. Certain indirect costs
could not be estimated accurately and are not included. A thorough
clean up of drydock floor space, trenches, tunnels, and altars can
lead to increased drydock time per ship. If such time is allowed for
in contract arrangements with shipowners, busy shipyard operators may
find that they cannot service as many ships per year and must
correspondingly suffer a drop in revenue. If increased time for
clean-up activities is not allowed for, the shipyard is faced with the
loss in revenue or additional charges to the ship owner. Frequently
at shipyards in this position, complete clean up prior to flooding is
not performed. Either way, time delays create dissatisfied customers,
and can harm shipyard reputations and good will as well as current and
future business prospects. These are important considerations which
can produce hidden costs not recognized as clean-up related.
On the other hand, the clean up of abrasive prior to flooding may
provide some economic benefits. When abrasive blasting has been
particularly heavy, collection of the abrasive may be required to
profitably carry out repair operations on a vessel. Thus, increased
clean-up efforts may provide benefits as well as increase costs.
However, this section does not present a cost/benefit analysis of the
operation. Only those costs are included that directly result from
the clean-up methods discussed.
IDENTIFICATION OF METHODOLOGY CURRENTLY USED IN BEST MANAGEMENT
PRACTICES
Best Management Practices, previously defined, arcs directed toward
clean up within the dock working area and control of water and
wastewster flows into and out of the dock. Wide differences are found
between facilities and conditions in facilities, and as a result of
these differences. Best Management as practiced at one dock may be
either inadequate or unnecessarily extensive if applied to another
dock.
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Any attempt to define a total cost of Best Management and to apply
this to specific facilities is misleading because of the differences
encountered. A preferred approach to defining cost is to evaluate
costs of individual operations, which can be applied in Best
Management Practices, and normalize these to a standard application
time, or extent. From such data the costs of Best Management can then
be synthesized for individual docks depending upon the specific
operations of Best Management required and the time or extent pf these
operations. This approach admittedly will not permit an exact
definition of costs because the components going into the values will
not account for variations between facilities, for example labor
rates. However, it will be possible to compare the costs attributed
to different degrees of Best Management Practices for any given
facility and to determine combinations of operations which may achieve
equivalent results at reduced expenditures.
Only costs associated with routine clean-up operations of Best
Management Practices are considered here. Costs resulting from events
such as oil and paint spills are not due to normal operations and are
not incurred on a regular basis. The operations considered, in
principal, can be applied in any facility but all would not
necessarily be applied at any given facility.
The cost of segregation and control of water and wastewater flows is
not addressed. Most such efforts require structural modifications to
the facility. This aspect of Best Management Practices is dock
specific. Differences in facility ages, construction, size and
configuration, and geologic and meteorologic conditions prohibit any
valid effort to generalize with respect to costs of modifications
needed to achieve water and wastewater segregation and control.
Clean-up operations for which costs are estimated here include both
mechanical and manual techniques. Mechanical operations use front
loaders, sweepers, backhoes, vacuum equipment, and closed cycle
blasting. Worker use of shovels, brooms, and hoses are manual
operations and in some cases are needed in combination with mechanical
methods.
UNIT COSTS OF BEST MANAGEMENT PRACTICES
The elements of cost which combine to make up the costs associated
with Best Management Practices include capital investment and
depreciation, operating and maintenance costs for equipment, labor
costs (with overhead), and contract costs where contractual
arrangements are made. When equipment is used for multiple purposes,
only one of which relates to the clean-up operations, the cost
attributed to management practices must be prorated on the basis of
the fractional time so used.
105
-------
The approach used in this section has been to define the costs
associated with methodologies used for clean up. These costs have
been normalized to one eight-hour shift. For comparing various
techniques which may be used in an existing facility, the unit costs
per shift will be multiplied by the number of shifts required for the
cleanup cycle.
Clean-up techniques and methodologies included in tM- breakdown
involve use of front loader, mechanical sweeper, vacuum equipment, and
backhoe operations. Labor costs for support of these operations, as
opposed to the direct operation costs, are separately identified and
in most instances represent manual operations when considered alone..
Disposal costs are estimated on the basis of unit volume.
Table VIII-1 summarizes the clean-up methodologies which may be used
to implement Best Management Practices. The applicability of each
method is shown. Where the cost of equipment or method varied due to
the presence of raised bilge block slides, two entries have been made
to allow for this effect. This has been done because of the higher
maintenance costs and life of mechanical equipment subjected to
operation over raised bilge block slides. Under these conditions,
depreciation over a three year period is used as opposed to eight
years for service in a dock having a smooth floor.
Table VIII-2 shows an estimated cost of solid waste removal from
shipyards.
106
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107
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Table VIII-2. COST OF DISPOSAL OF SOLID WASTE
REMOVED FROM DOCKS (INCLUDES HAULING AND LANDFILL FEES)
Light
Blasting
Heavy
Notes:
1.
2.
3.
4.
Tons of
Debris Volume Number of
Per Ship Cubic Yds Containers
200
1,350
128
862
8
53
Total Cost
$ per
Clean Up
1,000
6,625
Cost Data as of March to May, 1976.
Bulk Density assumed 116 Ib/cu ft.
Standard container has 16.4 cubic yard volume.
Cost per standard container is $125 for removal
and disposal.
In using the costs presented in Tables VIII-1 and VIII-2 the
operations required for best management techniques can be synthesized,,
Where mechanical equipment has been defined, only the cost of
operating the equipment is included. Additional costs resulting from
the need for shovellers to work in conjunction with front loaders (or
for crane operation to move machinery and collected debris to and from
the dock) must be added to define total cost of each operation.
Finally, these costs are approximate and do not reflect regional
variations, and are based on costs prevailing during the conduct of
this study in 1976.
-'=4*
COSTS ATTRIBUTED TO BEST MANAGEMENT PRACTICES VS. ENVIRONMENTAL COSTS
, «- .j
Regardless of other considerations clean up of graving docks and
floating drydocks must be performed at some time simply to permit the
repair and maintenance operations to be carried out. Some facilities
may find frequent clean up a necessary part of their total work
effort, while others may routinely go for long time periods between
clean up. Cost of clean up performed as normal maintenance cannot be
considered environmental charges.
Likewise, the cost of implementing a formal Best Management Practices
program cannot be charged entirely to environmental restrictions.
Such a program would be directed toward the management objectives, and
these are primarily for operational purposes. It is possible that an
108
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actual cost benefit may be realized as a result of a formal program to
remove wastes at regular times, but a detailed cost analysis would be
necessary to demonstrate the actual effect.
Only two operations have been identified which, in some instances, may
represent environmental costs: (1) implementation of a management
program requiring clean up at a frequency in great excess of that
necessary to achieve Best Management Practices, (2) costs incurred as
a result of special solids disposal methods required solely for
environmental protection.
In the first of these, only such costs resulting from the excess
practices imposed could be related to environmental concern. In the
more probable case such a program would be adopted at the discretion
of the facility management. Only where local regulations may be
stringent enough to force this type of program could part of it be
attributed to protecting the environment.
The second example is more clear cut. In general contractual
arrangements are in force for ultimate disposal of abrasive blasting
debris. This material most frequently is landfilled. Many landfills
are regulated to prevent contamination of ground and surface waters by
the materials disposed of in them. Some are not. It may be necessary,
in certain cases, to alter disposal practices by changing to certified
land fills in order to prevent potential damage to groundwater by
leaching constituents from abrasive blasting debris- In particular,
the disposal of organotin-based debris has been controlled by Naval
policies which require that it be sealed in steel drums. Costs
resulting from these practices may be considered environmentally
incurred.
In summary, shipyards which are currently operating under Best
Management Practices programs probably will experience no adverse
effects in, terms of excessive costs or reduced operations. Where
increased effort is necessary by other shipyards to achieve Best
Management Practices, minor effects may be noted.
109
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SECTION IX
ACKNOWLEDGEMENTS
The Environmental Protection Agency expresses appreciation for the
support in preparing this document provided by Hittman Associates,
Inc., Columbia, Maryland, under the overall direction of Mr. -Burton C.
Becker, Vice President, Operations. Mr. Dwight B. Emerson and Mr.
Jack Preston Overman shared direction of the day-to-day work on the
project.
Appreciation is extended to the staff of the Environmental Engineering
Department of Hittman Associates for their assistance during this
program. Specifically our thanks to:
Mr. V. Bruce May, Senior Chemical Engineer
Ms. Barbara A. White, Manuscript Coordinator
Mr. Thomas V. Bolan, III, Mechanical Engineer
Mr. Craig S. Koralek, chemical Engineer
Mr. Phillip E. Brown, Environmental Engineer
Mr, J. Patrick Carr, Consultant, 13..B. Navy (Ret.)
Acknowledgement and appreciation is given to Mr. Robert Blaser,
Hamilton Standard, Division of United Technologies Corporation, who
made an invaluable contribution to the preparation of this document.
Acknowledgement and appreciation is also given to Mr. Harold B.
Coughlin, Chief, Guidelines Implementation Branch, Effluent Guidelines
Division, for administrative support and to Ms. Kaye Starr, Ms. Nancy
Zrubek, and Ms. Carol Swann for their tireless and dedicated effort in
this manuscript.
111
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SECTION X
REFERENCES AND BIBLOIGRAPHY
REFERENCES
1. Hamilton Standard, Inc., Draft Development Document for Effluent
Limitations Guidelines and Standards of Performance for the
Machinery £ Mechanical Products Manufacturing Point Source
Category, EPA Contract No. 68-01-2914, Washington, DC, June 1975.
2. U.S. Environmental Protection Agency, Rationale for Water
Pollution Control at Shipbuilding and Ship Repair Facilities,
National Field Investigations Center* Denver, Colorado, August
1974..
3. U.S. Department of the Navy, Design Manual-Drydocking Facilities,
DM-29, Naval Facilities Engineering Command, Alexandria,
Virginia, February 1974.
4. Automation Industries, Inc., Environmental Impact Assessment of
Floating Drydocks Operated by the U.S. Navy, Vitro Laboratories
Division, Silver Spring, Maryland, May 1975*
5. Engineering-Science, Inc., Pollutional Effects of Drydock
Discharges, Berkeley, California, October 1973.
6. Moffatt & Nichol, Engineers, Industrial Waste and Ship Wastewater
Collection and Disposal Facility; Drydocks lf 2, and 3, Long
Beach Naval Shipyard, Long Beach, California, November 1975.
7. Birnbaum, Bruce, Experimental Grit Blasting of the U.S.S. James
Monroe (SSBN 662) Aboard the U.S.S. Alamagordo (ARDM 2) at Naval
Weapons Station, Charleston, South Carolina, Naval Ship
Engineering Center, Hyattsville, Maryland, October, 1975.
8. U.S. Department of the Navy, Final Environmental Impact
Statement: Abrasive-Blasting of Naval Ships* Hulls, Washington,
DC, November 1975.
9. Ticker, A. and Rodgers, S., Abatement of Pollution Caused by
Abrasive Blasting; Status in Naval Shipyards, Report 4549, Naval
Ship Research and Development Center, Bethesda, Maryland, July
1975.
113
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10. U.S. Department of Navy, "Military Specification: Sand,
Sandblast; and Grain, Abrasive - Ship Hull Blast Cleaning,"
Military Specification MIL-S-22262 (Ships), Washington, DC,
December 4, 1959.
11. Alig, Craig S., Loner Beach Naval Shipyard Drvdock Wastewater
Discharge Study, Report 4557, Naval Ship Research and Development
Center, Bethesda, Maryland, December 1975.
" T$ ^"" ' ~
12. Marks, Earl E., "Report on the Application and Use Experience of
the VAC-ALL Grit Removal Machine," Code 971, Long Beach Naval
Shipyard, Long Beach, California, 1974.
13. conn, Andrew F. and Rudy, S. Lee, Parameters for a Ship Hull
Cleaning System Using the CAVIJETTM Cavitating Water Jet Method,
Hydronautics, Inc., Laurel, Maryland, July 1975.
14. Ray, T.B., "Water Pollution Control Plant," submitted to the
State of Virginia Water Control Board as a requirement of NPDES
Permit fVA 4804, Newport News Shipbuilding and Drydock Co.,
Newport News, Virginia, 1975.
15. U.S. Environmental Protection Agency. Draft Report to the San
Diego Regional Water Quality Control Board on Guidelines for the
Control of Shipyard Pollutants, National Field Investigations
Center, Denver, Colorado, July 1, 1974.
16. Carr, Dodd S. and Kronstein, Max, "Antifouling Mechanism of
Shipbottom Finishes," Modern Paint and Coatings. Palmerton
Publishing Co., New York, New York, December 1975, pp. 23-27.
17. Barry, Joseph N., "Staff Report on Wastes Associated with
Shipbuilding and Repair Facilities in San Diego Bay," California
Regional Water Quality Control Board, San Diego Region, San
Diego, California, June 1972.
--rib**. .I""
114
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BIBLIOGRAPHY
1. Academy of Natural Sciences of Philadelphia, "Summary of Leaching
Study for Sun Shipbuilding and Dry Dock Company," Division of
Limnology and Ecology, Philadephia, Pennsylvania, 1974.
2. Alig, Craig S., Long Beach Naval Shipyard Drydock Wastewater
Discharge Study, Report 4557, Naval Ship Research and Development
Center, Bethesda, Maryland, December 1975.
3. Automation Industries, Inc., Environmental Impact Assessment of
Floating Drydocks Operated by the U.S. Navy. Vitro Laboratories
Division, Silver spring, Maryland, May 1975.
4. Barry, Joseph N., "Staff Report on Wastes Associated With
Shipbuilding and Repair Facilities In San Diego Bay," California
Regional Water Quality Control Board, San Diego Region, San
Diego^ California, June 1972.
5. Birnbaum, Bruce, Experimental Grit Blasting of the u.s.S. James
Monroe (SSBN 622) Aboard the U.S.S. Alamagordo (ARDM 2L at Naval
Weapons Station^ Charleston^ South Carolina, Naval Ship
Engineering Center, Hyattsville, Maryland, October, 1975.
6. California Air Resources Board, "Abrasive Blasting, Title 17,
California Administrative Code, Subchapter 6, State of
California, Sacramento, California, February 3, 1976.
7. California Water Resources Control Board, Water Quality Control.
Plan for Ocean Waters of California, State of California,
Sacramento, California, July 6, 1972,
8. Chan, D.B. and Saam, Richard D., "Drydock Wastewater Treatment
Study," U.S. Navy, Civil Engineering Laboratory, Construction.
Battalion Center, Port Hueneme, California, June 1975.
9. Conn, Andrew F. and Rudy, S. Lee, Parameters for a Ship Hull
Cleaning System Using The CAVIJETTM Cavitating Water Jet Method,
Hydronautics, Inc., Laurel, Maryland, July 1975.
10. Engineering-Science, Inc., Lower James River Basin Comprehensive
Water Quality Management Study, Planning Bulletin 217-B, State of
Virginia Water Control Boad, Richmond, Virginia, July 1974.
11. Engineering-Science, Inc., Pollutional Effects of Drydock
Discharges, Berkeley, California, October 1973.
115
-------
12. Hamilton Standard, Inc., Draft Development Document For Effluent
Limitations Guidelines and Standards of Performance for the
Machinery t> Mechanical Products Manufacturing Point source
Category, EPA Contract No. 68-01-2914, Washington, DC, June 1975.
13. Huggett, R.J. , Analyses of Sediment and Elutriate Samples from
the James River, Virginia, Virginia Institute of Marine Science,
Gloucester Point, Virginia, July 1975.
14. Huggett, R.J., Study of Channel Sediments; Baltimore Harbor,
Norfolk Harbor, York Entrance Channel. Virginia Institute of
Marine Science, Gloucester Point, Virginia, 1972*
15. Hurst, W. Calvin and Whiteneck, L.L., An Analysis of the Impact
From Completion of Yard Modernization, Todd Shipyards
Corporation, Los Angeles Division, San Pedro, California, Berths
103-109, Engineering Feasibility Studies, Inc., Los Angeles,
California, April 1975.
16. Johnson, Patricia G. and Villa, Orterio, Jr., Distribution of
Metals In Baltimore Harbor Sediments, Technical Report 59, U.S.
Environmental Protection Agency, Annapolis Field Office,
Annapolis, Maryland, 1974.
17. Marks, Earl E., "Report on the Application and Use Experience of
the VAC-ALL Grit Removal Machine," Code 971,, Long Beach Naval
Shipyard, Long Beach, California, 1974.
18. Moffatt & Nichol, Engineers, Industrial Waste and Ship Wastewater
Collection and Disposal Facility; Drydocks 1, £ and 3, Long Beach
Naval Shipyard, Long Beach, California, November 1975.
19. Newport News Shipbuilding and Dry Dock Company, "EPA Survey of
Wastewater Discharge from Graving #10 During the Repair and
Painting of the SS Claude Conway, May 1975," Laboratory Services
Report No. N-5327, Newport News, Virginia, December 5, 1974.
20. Partek Corporation of Houston, "Partek Liqua-Blaster TM,"
Houston, Texas, 1976.
21. Penningtpn, J.C., untitled letter to T.B. Ray at Newport News
Shipbuilding and Dry Dock Company, U.S. Environmental Protection
Agency, National Field Investigations Center, Denver, Colorado,
August 1974.
22. Price, R.A., "Texstar, Inc. Automatic Descaling Equipment
Demonstration at Avondale Shipyards, Inc.," memorandum, Avondale
Shipyards, Inc., New Orleans, Louisiana, June 24, 1975.
116
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23. Bay, T.B., "Comments on the Draft Development Document for
Machinery and Mechanical Products Manufacturers," letter to the
U..S. Environmental Protection Agency, Newport News Shipbuilding
and Dry Dock Co., Newport News, Virginia, August 1975.
24. Ray, T.B., "Water Pollution Control Plan," submitted to the State
of Virginia Water Control Board as a requirement of NPDES Permit
fVA 0004804, Newport News Shipbuilding and Dry Dock Co., Newport
News, Virginia 1975.
25. Ticker, A. and Rodgers, S., Abatement of Pollution Caused by
Abrasive Blasting; Status in Naval Shipyards, Report 4549, Naval
Ship Research and Development Center, Bethesda, .Maryland, July
1975.
26. Shierman, E.G., A Demonstration of the Myers-Sherman Vactor Model
700, U.S. Navy, Long Beach Naval Shipyard, Long Beach,
California, 1975.
27. U.S. Congress, Current Status of Shipyards, 1974 - Part 2t
hearings before the Seapower Subcommittee of the Committee on
Armed Services, House of
28. U.S. Department of Commerce and U.S. Department of Defense,
Principal Shipbuilding and Repair Facilities of the United
States, Naval Sea Systems Command, Washington, DC, 1970.
29. U.S. Department of Defense, "Military Specification: Paint,
Antifouling, Vinyl-Red (Formula No. 121/63), Military
Specficiation MIL-P-15931B, Amendment 2, Washington, DC, April
13, 1970.
30. U.S. Department of Defense, "Military Specification: Primer
Coating, Shipyard, Vinyl-Red Lead (Formula 119), Military
Specification MIL-P-15929C, Washington, DC, October 24, 1972.
31. U.S. Department of the Navy, Design Manual - Drydocfring
Facilities, DM-29, Naval Facilities Engineering Command,
Alexandria, Virginia, February 1974.
32* U.S. Department of the Navy, Docking Instructions and Routine
Work in Drydock, Naval Ships1 Technical Manual Chapter 9070,
Naval Sea Systems Command, Washington, DC, November 1, 1972.
33. U.S. Department of the Navy, Environmenta1 Protection Manual,
OPNAV Instruction 6240.3, Office of the Chief of Naval
Operations, Washington, DC, 1975.
117
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34. U.S. Department of the Navy, Final Environmental Impact
Statement; Abrasive Blasting of Naval Shipsj Hulls, Naval Sea
Systems Command, Washington, DC, November 1975.
35. U-S. Department of the Navy, "Military Specification: Sand,
Sandblast; and Grain, Abrasive - Ship Hull Blast Cleaning,"
Military Specification MIL-S-22262 (Ships), Washington, DC,
December 4, 1959.
36. U.S. Department of the Navy, "»Mini Scope1: Shipalt ARD-193,
Industrial Waste Disposal,: Boston Naval Shipyard, Code 2060.2,
Boston, Massachusetts, September 12, 1975..
o
37. U.S. Department of the Navy, P-174 Drydock Water Pollution
Abatement, Fiscal Year - 1979, Military Construction Program,
Long Beach Naval Shipyard, Long Beach, California, May 1, 1976.
38. U.S. Department of the Navy, "Revised Sandblasting Procedures,"
Naval Ships' Technical Manual Chapter 9190, Amendment 1, Naval
Sea Systems Command, Washington, DC, August 1, 1975.
39. U.S. Department of the Navy, A Study of Sediments and soil
Samples From Pearl Harbor Area, Facilities Engineering Command,
Civil Engineering Laboratory, Port Hueneme, California, March
1973.
40. U.S. Environmental Protection Agency, "Determination of Metals in
Salt Water by Atomic Absorption," National Field Investigations
Center, Denver, Colorado, 1974.
41. U.S. Environmental Protection Agency, Draft Report to the San
Diego Regional Water Quality Control Board on Guidelines for the
Control of Shipyard Pollutants, National Field Investigations
Center, Denver, Colorado, July 1, 1974.
42. U.S. Environmental Protection Agency, Rationale for Water
Pollution Control at Shipbuilding and Ship Repair Facilities,
National Field Investigations Center, Denver, Colorado, August
1974.
43. U.S. Environmental Protection Agency, "Study Plan for Shipyard
Field Survey, Newport News, Virginia," National Field
Investigations Center, Denver, Colorado, May 1974.
44. Virginia Institute of Marine Science, Study of Channel Sedimentsf
James River and Hampton Roads Area, Gloucester Point, Virginia,
August 1971.
118
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45. Carr, Dodd S. and Kronstein, Max, "Anti-fouling Mechanism of
Shipbottom Finishes," Modern Paint and Coatings, Palmerton
Publishing Co., New York, New York December 1975, pp. 23-27.
46. "At Last, A. Lasting Bottom Paint," Washington Star News,
Washington, DC, April 4, 1976.
47. "Bay's Project on Schedule," World Dredging and .Marine
Construction, Symcon Publishing Co., San Pedro, California, April
1976, p. 8.
48. Hassani, Jay J. and Millard, Charles F. , "Graving Dock for
300,000-Ton Ships," Civil Engineering, American Society of Civil
Engineers, New York, New York; June 1971.
49. "Navy Device Soaks Up Spilled Oil," Navy Times, Washington, DC,
April 12, 1976, p. 44.
50. "New Paint Keeps Barnacles At Bay," Navy Times, Washington, DC,
April 19, 1976, p. 3.
51. Clark, Allen, "Shipyard Problems with Oily Wastes," Proceedings
of the International Conference on Waste Oil Recovery and Reuse,
February 12-14, 1974, Information Transfer, Inc., Rockville,
Maryland, 1974.
52. United States Department of Defense and Department of Commerce,
Principal Shipbuilding and Repair Facilities of the United
States, Office of the Coordinator for Ship Repair and Conversion,
Naval Sea Systems Command, September 1, 1978.
119
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SECTION XI
GLOSSARY
Anticorrosive paints - the initial layer(s) of paint on a ship»s hull.
The purpose of these paints is to prevent rusting.
Antifouling paints - the final layer(s) of paint applied to a shipfs
hull. They inhibit the growth of marine organisms on a ship's
hull.
Bare Metal - hull metal that has had all paint and marine organisms
abraded in preparation for repainting..
Building Basins - a graving dock used solely for ship construction.
Eilge water - water and oil that collects in the lower hull.
Bilge blocks - side blocks placed on the drydock floor. They are
located according to the dimensions specific to a particular ship
and help stabilize and support the drydocked ship.
Bilge block slides - raised lateral tracks built into many older
docks, used to move and position bilge blocks-
Broomed clean - see "Scraped or Broomed clean".
Closed cycle blaster - a type of abrasive blaster that reuses
abrasive, usually steel shot, and often collects removed paint
and marine organisms.
Cooling water - non-potable water used for shipboard purposes such as
air-conditioning and condenser cooling during the drydocked
period.
Deflooding - the pumping out of the flooded (filled) drydocks.
Dewatering - see deflooding.
Dock leakage - hydrostatic relief water, gate seepage, and other water
leakage other than ship originating wastes that leak into the
dock floor.
Drainage discharge - the daily effluent from a drydock.. This does not
include deflooding water.
Dregs - silt, grit, or other particles deposited on a dock floor
during dewatering.
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Dry abrasive blasting - a process to remove paint, rust, and marine
organisms from a ship1s hull. The abrasive usually a copper slag
or sand, is conveyed in a medium of .high pressure air through a
nozzle.
Drydock - either a graving dock or a floating drydock. Also.to place
a ship in drydock.
Flap gate - a rigid one piece gate hanged at the bottom.
Floating - raising of a submerged floating drydock.
Floating caisson gate - the most common type of graving dock gate. It
is floatable and can be moved to permit, entry and departure of
the ship.
Floating drydock - a submersible moveable platform to enable repairs
and maintenance of ships out of water.
Flooded dock - the filled dock following flooding.
Flooding - the filling of a graving dock with water, to permit entry or
departure of a ship.
Flush deck construction - a flat dock floor not having permanent bilge
block slides.
Fresh grit - unused abrasive.
Front loaders - a type of machinery, similar to a bull dozer used to
scrap collect and transfer spent paint, grit and marine organisms
that collect on the dock floor during blasting.
Gate - the closure that separates a graving dock from the harbor. It
is removed to permit entry and departure of the ship.
Graving dock - a dry basin, below water level that is used for repair
and maintenance of ships.
Grit - abrasive.
Hydroblasting - the use of a high pressure water stream to remove
paint, rust, and marine organisms from a ship's hull.
Hydrostatic relief - the water that leaks into a dock through holes
and cracks in the floors and walls of a graving dock. This
equilibrates groundwater pressure.
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Keel blocks - blocks positioned on the floor of the dock, fitted to
match the keel surface of the ship. The drydocked ship is
positioned on the blocks.
Launch water - the water in a flooded graving dock.
Manual clean up - use of shovels, brooms, and other equipment which is
not power operated to clean the dock floor.
Mechanical clean up - use of machinery, such as front end loaders,
mechanical sweepers, or vacuum cleaners to clean the dock floor.
Miter gate - a pair of gate leaves* hinged at the dock walls which
swing open to allow passage of a ship into and from a graving
dock.
Primer - see "anticorrosive paints."
Sand - often used to describe any dry abrasive.
Sand blast - dry abrasive blasting.
Sand sweep - a light dry abrasive blast used to remove only the outer
layers of paint and marine growth from a ships hull.
"Scraped or Broomed Clean" - using shovels, mechanical loaders,
mechanical sweepers, or brooms to remove abrasive blasting
debris.
Scupper boxes - containers used to collect water that runs off a ship
deck.
Shipboard wastes - all effluent discharges originating from a
drydocked ship. Included are sanitary wastes, bilge water,
cooling water, and cleaning wastes.
Sinking - flooding of caissons and lowering of floating drydock to
permit a ship to be positioned over the dock prior to floating of
the dock and docking.
Slurry blasting - see "wet abrasive blasting,"
Soil chutes - flexible hoses, usually made of rubber coated nylon or
canvas used to transfer shipboard wastes from the docked vessel
to the appropriate disposal system.
Spent abrasive - used grit and spent paint, rust, and marine organisms
that collect on the dock floor during blasting.
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Stripping - see "drainage discharge."
Wash down - the hosing down of the dock, and sides of the ship
following docking to remove silt, marine organisms, etc.
Water cone abrasive blasting - a type of blasting that uses a cone of
water to surround the stream of air and abrasive as they leave
the nozzle.
Wet abrasive blasting - a process to remove paint, rust, and marine
growth from ship's hulls, in which high pressure water propels an
abrasive.
White metal - see "bare metal,"
124
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TABLE
METRIC TABLE
CONVERSION TABLE
MULTIPLY (ENGLISH UNITS) by TO OBTAIN (METRIC UNITS)
ENGLISH UNIT ABBREVIATION CONVERSION ABBREVIATION METRIC UNIT
acre ac
acre - feet ac ft
British Thermal
Unit BTU
British Thermal
Unit/pound BTU/lb
cubic feet/minute cfm
cubic feet/second cfs
cubic feet cu ft
cubic feet cu ft
cubic Inches cu In
degree Fahrenheit °F
feet ft
gallon gal
gallon/minute gpm
horsepower hp
Inches in
Inches of mercury in Hg
pounds Ib
million gallons/day mgd
mile mi
pound/square
inch (gauge) psig
square feet sq ft
square Inches sq in
ton (short) ton
yard yd
0.405
1233.5
0.252
ha
cu m
kg cal
0.555
0.028
1.7
0.028
28.32
16.39
0.555(6F-32)*
0.3048
3.785
0.0631
0.7457
2.54
0.03342
0.454
785
1.609
kg cal /kg
cu m/min
cu m/min
cu m
1
cu cm
C
m
1
I/sec
kw
cm
atm
kg
cu m/day
km
(0.06805 psig +1)* atm
0.0929 sq m
6.452 sq cm
0.907 kkg
0.9144 m
* Actual conversion, not a multiplier
hectares
cubic meters
kilogram - calories
kilogram calories/kilogram
cubic meters/minute
cubic meters/minute
cubic meters
liters
cubic centimeters
degree Centigrade
meters
liters
liters/second
killowatts
centimeters
atmospheres
kilograms
cubic meters/day
kilometer
atmospheres (absolute)
square meters
square centimeters
metric ton (1000 kilograms)
meter
126
U. S. GOVERNMENT PRINTING OFFICE : 1979 C - 307-065
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United States
Environmental Protection
Agency
Washington DC 20460
^ Special
OHicial Business Fourth-Class
Penalty (or Private Use $300 pate
' rv,.r. Book
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