PARTICULATE EMISSION FACTORS AND
FEASIBILITY OF EMISSION CONTROLS FOR
SHIPLOADING OPERATIONS AT
THE BUNGE AND LOUIS DREYFUS
PORTLAND, OREGON GRAIN TERMINALS
Final Report
GCA/TECHNOLOGY DIVISION MA
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GCA-TR-79-77-C
GRAIN TERMINAL CONTROL STUDY
Contract No. 68-01-4143
Technical Service Area 1
Task Order No. 69
EPA Project Officer
EPA Task Officer
Mr. John R. Busik
Division of Stationary Source
En forcement
401 M Street, S.W.
Washington, D.C. 20460
Ms. Betty Swan
U.S. EPA Region X
1200 6th Ave.
Seattle, WA 98101
PARTICULATE EMISSION FACTORS AND
FEASIBILITY OF EMISSION CONTROLS FOR
SHIPL0ADING OPERATIONS AT
THE BUNGE AND LOUIS DREYFUS
PORTLAND, OREGON GRAIN TERMINALS
by
Ronald K. Bell
Paul J. Exner
Robert R. Hall
GCA CORPORATION
GCA/TECHNOLOGY DIVISION
Bedford, Massachusetts
April 1980
U.S. ENVIRONMENTAL PROTECTION AGENCY
Division of Stationary Source Enforcement
Final Report
Washington, D.C. 20460
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DISCLAIMER
This Final Report was prepared for the U.S. Environmental Protection
Agency by GCA Corporation, CCA/Technology Division, Burlington Road, Bedford,
Massachusetts 01730 in fulfillment of Contract No. 68-01-4143, Technical Ser-
vice Area .1, Task Order No. 69. The opinions, findings, and conclusions ex-
pressed are those of the authors and not necessarily those of the Environmen-
tal Protection Agency. Mention of company or product names is not to be con-
sidered as an endorsement by the Environmental Protection Agency.
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ABSTRACT
Observations of shiploading operations including the tween-decker load-
ing and topping-off of bulk carriers in Tacoma, Washington, and Portland,
Oregon are discussed. An evaluation of the compliance status and/or feasi-
bility of compliance of shiploading operations at the Portland, Oregon ele-
vators with state visible emissions regulations is presented. Particulate
emission estimates at Portland elevators have been calculated using emission
factors for shiploading.
id i
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CONTENTS
Abstract iii
Figures v
Tables ¦ v
1. Summary and Conclustions 1
Summary 1
Conclusions 3
2. Background 4
Loading operations 4
Visible emissions regulations 6
Emission control technology 7
3. Site Inspections and Visible Emission Measurements 14
Tween-decker loading at United Grain in
Tacoma, Washington 14
Bulk carrier loading at the Louis Dreyfus
facility 17
4. Technical Feasibility of Meeting Opacity Regulations
by Conventional Control Systems 24
Tent aspiration pollution control systems 24
Dead-box control 28
Submerged loading control 28
5. Emission Estimates 30
Kcferences 32
Appendi cos
A. Conversion Factors for Selected Metric and
British Units 34
B. Cargo Preference Act 35
iv
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FIGURES
Number Page
1 Schematic of bulk carrier, tanker and
'tween-decker grain loading 5
2 Tent and suction dust control system 8
3 Dead-box in use at Cargill in Portland 10
b Submerged loader in use at Cargill in Seattle 11
5 Trimming a tween-decker 15
6 Grain loading operations at the Louis Dreyfus
elevator 19
7 Side view of typical bulk loading procedure 21
TABLES
Number Page
1 Summary of Visual Emissions Recorded during
Uncontrolled Loading of a Tween-decker 18
2 Visible Emissions Generated During Topping-off
of a Bulk Carried Hold at Louis Dreyfus 22
3 Average Particulate Emission Factors 30
v
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SECTION 1
SUMMARY AND CONCLUSIONS
SUMMARY
The Bunge and Louis Dreyfus Corporation shiploading facilities in Portland,
Oregon, currently employ tent aspiration air pollution control systems to con-
trol particulate emissions generated during shiploading operations. Tent con-
trol is generally used during bulk loading of bulk carriers, but not during
topping-off of bulk carriers, or during loading of tween-deckers. Control
strategies capable of achieving compliance with Oregon State visible emission
regulation during the topping-off phase and tween-decker loading have been
invest igated.
An inspection of a tween-decker loading operation was conducted at United
Grain in Tacoma, Washington. Tween-decker loading operations are complicated
by horizontal intermediate decks- in the hold. Operators must remain in the
hold during loading to operate a trimming device which throws grain under the
intermediate decks. Operating the trimmer is hazardous due to such factors
as: communication difficulties between trimmer operators in the hold and load-
ing operators at deck level, difficulties in handling the powerful 2500 pound
trimmer suspended by the ships fall, poor footing on the surface of the grain
pile, and the inaccessibility of trimmer operators in the hold during emergency
situations. Placing a tent over the hold would compound the hazards by further
limiting communication, and increasing the suspended particulate concentration,
thus, limiting visibility in the hold and causing breathing difficulties. In
addition, the use of tent control would at least triple the time required to
load a tween decker. The additional loading time is a result of the continual
need to reposition the trimming device. Repositioning requires that the hold
be open to operate the ships fall and loading spout.
Observations of visible emissions generated during tween-decker loading
show that emissions in excess of 20 percent are common occurrences. Particu-
late emission factors for tween-decker loading are similar to those for uncon-
trolled bulk carrier loading, 55 g/t (0.11 lb/ton) for total particulates.
TrimmLng machines can be modified so that emissions from the loading of
tween-deckers can be controlled when using dead-boxes. However, the costs of
retrofitting the present facilities with dead boxes would approach $5 million
per facility. The impact on profits has not been determined.
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Several inspections of bulk carrier topping-off operations were conducted
at the Louis Dreyfus facility which currently employs a tent aspiration dust
control (system. The amount of grain loaded during topping-off varied from 20
to 40 percent of the total volume of grain loaded. In general, poor topping-
off procedures were witnessed. The holds were bulk filled at one end until
the grain pile came to within about 4 feet of the top, at which time the tents
were removed. This procedure left more than 30 percent of the grain to be
loaded during topping-off. Grain terminal operators and longshoremen who were
interviewed agreed that in isolated cases topping-off could be limited to 15
percent by filling more of the hold during the bulk loading phase. However,
it was agreed that limiting topping-off to 25 percent is a more reasonable
figure and one which operators could comply with a majority of the time.
Limiting topping-off to 25 percent results in an average emission factor of
14 g/t (0.028 lb/ton) compared to 55 g/t (0.11 lb/ton) for uncontrolled
shiploading.
There were no visible emissions during bulk loading when the tents were
in use. Visible emissions observed during topping-off varied with the loading
rate. Based on limited data at the full loading rate (1000 ton/hr) the aver-
age opacity was 75 percent while at 25 percent of the full loading rate (250
ton/hr) the average opacity of the visible emissions was 28 percent. Viola-
tions of Oregon state visible emission standards were observed during the en-
tire topping-off phase. Although emissions could be reduced by holding the
loading spouts closer to the grain level, visible emissions would still exceed
20 percent opacity during portions of the topping-off phase.
Submerged loading systems, in which the grain spout is buried under the
grain pile during loading, are effective in reducing emissions. Emission fac-
tors for submerged loading are similar to those for dead-box control which is
0.3 g/ton when operated well. However, it is the consensus of grain terminal
design engineers that the present Bunge and Dreyfus galleries would not handle
the additional weight and torque which would result from attaching additional
telescoping sections and aspiration tubes to the loading spouts. In addition,
the present loading galleries are not high enough to provide the kinetic energy
for the grain falling down the chute to break through the grain pile. Also
the galleries are not high enough to position the lengthened loading spouts
from the dock into the hold.
Consequently, considering the capital costs associated with refurbishing
a gallery, submerged .loading would approach the costs associated with going to
dead-box control. This would be about $5,000,000 depending on the number of
loading spouts to be converted. A cost of $5 million amortized over 15 years
at 15 percent interest would cost about $850,000 per year. Thus, assuming
1 million metric tons of grain is loaded per year, these costs would be about
2.3 cents per bushel. The costs of emission control appears to be high rela-
tive to the profit of a terminal elevator which is only 2.1 cents per bushel.
It should be noted that control costs of 2.3 cents per bushel are small com-
pared to the selling price of grain which is $4 to $5 per bushel. However,
the ability of terminal owners to revise prices to cover increased costs and
maintain profit margins has not been evaluated in^ this study.
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Applicable regulations and practices having impacts on the loading of
grain in other geographical areas of the United States and Canada were inves-
tigated. It was determined that the emissions problems associated with
topping-off and twcen-decker loading are prevalent at all grain loading
facilities which employ tent aspiration control. The State of Ohio Environ-
mental Protection Agency has proposed regulations which exempt emissions gen-
erated during topping-off and tween-decker loading. However, a proposed def-
inition sLates that topping-off is not to be more than 25 percent of the total
amount loaded. This proposed regulation may be enforced through a permit sys-
tem whereby grain terminals are required to submit topping-off data on a
monthly or bimonthly basis.
CONCLUSIONS
The Bunge and Louis Dreyfus facilities would require major refurbishments
to retrofit the existing galleries, spouts, and aspiration systems to submerged
loading. The costs associated with retrofitting submerged loading would ap-
proach the costs of going to dead-box control which is about $5 million per
facility. The ability of terminal owners to raise grain prices to cover in-
creased costs and maintain profit margins has not been evaluated.
Considering the high capital costs of retrofitting the Bunge and Dreyfus
facilities with a submerged loading system, proper use of the tent aspiration
control system is likely to be the only reasonable available control option.
However, in order for tent control to be effective in minimizing emissions,
proper bulk loading procedures must be followed. It is possible to limit the
topping-off phase to less than 25 percent of the total amount loaded by allow-
ing the grain pile in the center of the hold to reach the top of the hold
before the tent is removed.
The loading rate should be reduced during topping-off to lower the opacity
of visible emissions. At 25 percent of the full loading rate visible emissions
observed averaged 28 percent opacity. This value is more than 50. percent lower
than opacity observed at the full loading rate. In addition, the loading
spout should be kept as close as possible to the grain to further reduce vis-
ible emissions.
Observations of current topping-off procedures showed that the amount of
grain loaded uncontrolled exceeded 30 percent. Consequently, enforceable regu-
lations limiting topping off to reasonable levels; i.e., less than 25 percent,
are necessary. At present, longshoremen are not required to meet any standard.
Therefore, they remove tents when they see fit, regardless of the amount of
grain which will be loaded uncontrolled.
Based on the data collected and observations'made during this study,
CCA has determined it is not technically feasible to employ tent aspiration
control systems during tween-decker loading. Using tents would complicate
loading procedures such that risks involved in operating the trimming device
wouJd he greatly Increased. It is not reasonable to request trimmer opera-
tions to work in a tented hold.
3
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SECTION 2
BACKGROUND
LOADING OPERATIONS
Grain loaded into ships at a terminal grain elevator is conveyed from
the elevators to a gallery above the dock, from which it is dropped down one
of several long telescoping spouts, into a hold.* Grain loading rates are
usually on the order of 1,000 metric tons (1,000 long tons) per hour. The
spouts can be either vertical or slanted and are typically 15 meters (50 feet)
long. These generally have the capacity to telescope in their length by
6 to 12 meters (20 to 40 feet). As grain falls down the spout, it pulls air
along with it. This air becomes quite dusty and the entrained dust is emitted
at the bottom of the spout. More dust is emitted as the grain falls from the
bottom of the spout into the hold. State and/or local visible emission regula-
tions arc often exceeded during uncontrolled shiploading operations. The
amount of dust generated depends on the length of the loading spout, the dis-
tance between the bottom of the spout and the grain, and the "dustiness" of the
grain. Conversation with longshoremen and elevator operators, and observation
of loading operations indicate that wheat is the least dusty grain, and that
spring wheat tends to be the dustiest type of wheat. Corn and barley are
dustier than spring wheat, and soybeans are dustier still. Finally, pellets
are much dustier than any grain. Pellets are animal food consisting of bits
of pulp which are compressed to form cylinders about 1 cm (0.5 in.) in diameter
and 2 cm (1 in.) long.
There are three types of ships which are used to haul grain: bulk car-
riers, tween-deckers, and tankers. Bulk carriers are used for about 90 percent
of the grain shipped from U.S. ports.
The holds of a bulk-carrier are unobstructed by internal bulkheads, and
have large openings which permit easy access. The loading operation for a
bulk-carrier can be broken into two stages: bulk loading, and topping-off.
In bulk loading the grain is simply poured into the hold. During topping-off
the loading spout must be moved about over the hold opening so that when the
hold is filled there will be no air spaces under the sides of the hold or
under the hold cover (see Figure 1). This prevents listing of the ship. Bulk
cnrrLers are also known as self trimmers because special trimming methods
discussed later are not needed. It is generally more difficult to control
dust emissions during topping-off because the grain spout must be moved
frequently and emissions are more affected by the wind.
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(NOT DRAWN TO SCALE)
Figure 1. Schematic of bulk carrier, tanker and 'tween-decker grain loading.
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The holds of a tween-decker contain horizontal intermediate decks (see
Figure 1). In the loading of a tween-decker, special care must be taken to
TL1J beneath these decks to prevent listing of the ship at sea. Devices
(commonly called conveyors, slingers, trimmers, slides and other terms) to
throw the grain into the corners of the hold are necessary. In addition,
men must get into the hold to operate the trimming device. More dust is re-
ported to be generated in the loading of tween-deckers than in the loading
of bulk carriers, because of the use of conveyors and slides.
Tankers are designed to carry liquid, but are sometimes used for grain.
The holds may contain vertical bulkheads, and generally have small hold
openings. These often necessitate the use of funnels to load the holds.2
The Use of Tween-Deckers
Tween-deckers are older ships which are no longer built, having been
replaced by more modern bulk carriers. Recent figures show that tween-deckers
account for approximately 8 percent of the total number of ships loaded at
Portland facilities.^'1' On the average, tween-decker cargo capacity is approxi-
mately 50 percent less than that of a bulk carrier. Thus, approximately 4 per-
cent of the grain shipped from Portland terminals is shipped aboard tween-
deckers. However, this figure is an average and varies depending on the nature
of export trading. Public Law 664 "The Cargo Preference Act" states that when
exporting to foreign nations without provisions for reimbursement 50 percent
of the gross tonnage of equipment, materials or commodities shall be shipped
on United States-flag commercial vessels. (See Appendix B). As a result,
during export programs affected by this law, many tween-deckers are put into
service to meet the 50 percent requirement. In recent years tween-decker load-
ing at Portland terminals has accounted for as high as 18 percent of the total
number of ships loaded over a 6-month period.
Eventually the o.lder tween-decker fleet will be diminished as each ship
Ls permanently taken out of service. However, the number of tween-deckers
loaded at Portland facilities is not expected to change in the immediate
future. Grain terminal operators who were interviewed felt that the use of
tween-deckers will remain at its current level for several years.
VISIBLE EMISSIONS REGULATIONS
Visible emissions regulations vary from state to state. The general
Oregon State regulation for visible emissions states that the opacity of
emission must not exceed 40 percent for more than 3 minutes of any hour. A
mucii more stringent state regulation applies to "special control areas" in
the state, such as the City of Portland and the Northwest Regional Area of
Oregon. This regulation states that the opacity of visible emissions must
not exceed 20 percent for more than 30 seconds in any hour (Oregon Adminis-
trative Rule 340-28-070).5 The grain terminals in the Portland area are
subject to this latter regulation.
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EMISSION CONTROL TECHNOLOGY
Uncontrolled particulate emissions from shiploading at grain terminals
generally have opacities which average over 30 percent with short-terra
(6 minute averages) often exceeding 40 percent. Control of these emissions
Is complicated by the fact that the deck level of a ship will vary with the
tide or river stage, the type of ship, and the trim of the ship. Three types
of control systems are presently used to control shiploading emissions:
aspirated tent systems, "dead-box" systems, and submerged loading systems.
Aspirated Tent Systems
In tent control, the emission of dust generated by grain falling into
a hold is prevented by covering the top of the hold with one or several tar-
paulin (s) or tent(s) (Figure 2). Grain is poured through a small hole in the
tent at a rate of about 1,000 t/hr. Dust laden air is drawn from under the
tent to a control device, usually a fabric filter, through one or more as-
piration hoses. These can be attached to the side of the loading spout, or
inserted under the side of the tent. The total aspiration rate from a hold
ranges up to 280 m3/min (10,000 cfin). Tent systems can be used with either
vertical, or slanted loading spouts, but the spouts must be capable of tele-
scoping by about 6 meters (20 feet) in length so that they can reach the hold
opening level regardless of the tide stage, or the trim of the ship.
Tent control systems, when properly used, completely eliminate visible
emissions during the bulk loading phase, however, they are not used in all
circumstances. During topping-off, the tents are removed so that the loading
spouts can be moved, and so that the operators of the loading spouts can make
sure that the grain is properly distributed and the hold is completely filled.
Also, tents apparently cannot be used when tween-deckers are being loaded, as
men must remain inside the hold.6»fi
In early 1978, the use of tents generated concern among Portland area
stevedores, as they suggested that an explosion hazard could be caused by the
dust concentrations in tent controlled ship holds. GCA conducted tests to
determine whether dust concentrations approached or exceeded the lower explo-
sive limit.'-' It was determined that the dust levels are well below the lower
explosive limit of 40 g/m3 for wheat dust. Average dust concentrations over
5 to 20 mLnute sampling intervals were 0.40 g/m3 with a maximum value of
1.1 g/m3. Graphical plots on log-probability paper of the distribution mea-
sured and estimated dust concentrations indicated an insignificant (less than
1 chance in 10,000) chance of exceeding about 5 g/m as either a 1- or 10-
minute average. Tents are currently being used by Portland area shiploading
facilities after resolving the question of an explosive hazard.
The major capital cost of retrofitting tent control to an existing facil-
ity wouLd be the cost of the aspiration and fabric filtration systems. This
cost would be about $30,000 dollars/loading leg.^
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Dead-Box
A more versatile metliod of controlling shiploading emissions is the use
of a "dead-box" (Figure 3). Grain is dropped through a vertical chute into a
dead-box, from which it is allowed to fall a short distance into the hold.
Typical grain flow rates for dead-box systems range from 1,000 to 2,000 t/hr.
The dead-box greatly reduces the velocity of grain which falls into it, and
thus reduces the amount of dust generated at the impact site of the grain in
the hold. Dust generated as the grain drops through the chute, and upon im-
pact of the grain with the baffles in the dead-box is drawn from the top of
the box to a fabric filtration system.
A dead-box should be suspended 15 to 30 cm (6 to 12 in.) above the grain
level in the hold, because dead-box performance deteriorates rapidly as height
increases. The distance to the grain level varies with the depth of the ship,
water level around the ship and the amount of grain in the hold. In order to
hold the dead-box near the grain during all phases of loading, the telescoping
range of the loading chute must be about 12 meters (40 feet). >12 Dead-box
control can be used to reduce emissions during topping-off as well as during
bulk-loading. It is also expected to reduce emissions from tween-decker
loading. Some dust emission would, however, be expected from the conveyors
or'slides used to throw grain to the sides of the holds.
The cost of retrofitting a dead-box control system to an existing facility
would be much higher than that of retrofitting a tent system. A dead-box sys-
tem would generally require major modifications to the loading equipment. A
new gallery would almost certainly be needed to support the additional weight
of,the dead-boxes. Major modifications to the dock which supports the gallery
might also be necessary. The total cost would vary from elevator to elevator,
depending on the gallery and dock in use at the elevator in question. The
consensus of opinion of grain elevator owners and operators and equipment sup-
pliers is that a cost estimate of $1 million per loading leg would not be
unreasonable.
Submerged Loading
A submerged loading technique for controlling dust emissions from ship-
loading was developed at the Cargill terminal in Seattle, Washington. The
bottom of the loading spout is actually buried below the grain level in the
hold (Figure 4). Grain falling down the chute has .sufficient kinetic energy
to push its way out of the bottom of the chute. Dust generated as the grain
falls down the spout and when it hits the grain in the hold is removed through
a port about 3 meters (10 feet) from the bottom of the spout. Dust laden air
is drawn through a pipe attached to the loading spout to a fabric filtration
system.
The grain loading rate used with this system is generally 1,500 tons/hr,
and the aspiration rate is about 325 m3/min (12,000 cfm). The grain spouts are
about 30 meters (90 feet) long, and can telescope by about 12 meters (40 feet) ,
so that the top of the spout can almost always reach the grain level in the
hold. The tip is generally kept buried 15 to 30 cm (6 to 12 in.) under the
grain level. All of the movement of the grain spout is controlled by fnotors
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PERFORATED
METAL
OPENING
(NOT OH AWN TO SCALE)
Figure li. IJcad-box in use at Cargill in Portland.
10
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whJcli can move the spout even when it is submerged. A Roto-Bin-Dicator® *
sensor Is located near the bottom of the leg, and shuts off the grain conveyors
to the leg when the leg becomes clogged. This Instrument is an electro-
mechanical device consisting of a pressure sensitive diaphragm that actuates
an electrical circuit when the pressure created by the grain exceeds a pre-
set level.
The Cargill-Seattle control system can be used either with the grain spout
tip slightly submerged, or with the tip slightly above grain level. If the
tip is kept within 15 to 30 cm (6 to 12 in.) above the grain level, the visible
emissLons should remain below the 20 percent opacity level. If the spout is
kept bur Led by 15 to 30 cm, visible emissions are completely eliminated.13
The grain spout should be kept buried, but should not be allowed to clog. When
the spout clogs, it must be lifted out of the grain, causing visible emissions.
During topping-off, tlie spout must be moved slowly, to prevent the tip from
surfacing. The submerged loading system is effective both during bulk-loading
and topping-off of bulk carriers. For tween-decker loading, the Cargill-Seattle
terminal has a trimmer which can be attached to the aspiration tube on the
grain spout, so that trimmer dust emissions during tween-decker loading can
also be reduced.
The capital cost of retrofitting a submerged loading system to an existing
facility would depend on the loading spouts, gallery, dock and aspiration sys-
tem in use at the facility in question. Such a retrofit would necessitate the
attachment of telescoping aspiration tubes to the loading spouts, and would
probably require additional telescoping capabilities for the spouts. Submerged
loading would require a spout telescoping capability of 12 meters (40 feet) ,
whereas spouts at most terminals can only be extended by about 6 meters (20
feet). From conversations with elevator operators and manufacturers of air
pollution control equipment for grain elevators,14*20 a rough estimate of the
cost of such additions has been obtained. The cost would be on the order of
$20,000 per leg. If there is no existing aspiration system at the facility
in question, or if the existing system is not capable of handling the extra
Load of a submerged loading system, the cost would be much higher. Also, gal-
leries at most terminals were not designed to handle the additional weight and
torque of aspiration tubes and additional telescoping sections. Thus, instal-
lation of a control system similar to that at Cargill-Seattle may require re-
furbishing of the gallery, and perhaps even the loading dock. The cost of
such work would probably approach the cost of retrofitting dead-box control,
about $1 million loading spout.
Comparison of Tents, Dead-Boxes and Submerged Loading Systems
Tents with aspiration are inexpensive to retrofit relative to the other
two control technologies. They are very effective, during bulk loading; com-
pletely eliminating visible emissions with practically no operator attention.
However, tents do not control emissions during topping-off or tween-decker
loadings. Also tents do require additional work and time to set up before
Binidicator - 800-521-6361, P.O. Box 9, 1915 Dove St., Port Huron, Michigan
48060
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loading can be started. Setup time can be expected to decrease significantly
as stevedores gain experience in use of the tent. High winds can also cause
problems with tent control systems but this is a very infrequent problem in
the Portland area.
Dead-box control systems require special galleries with sufficient height
and strength to handle the loading spouts and provide adequate manueverability.
These systems operate in a vertical loading mode and the heavy spouts must be
moved over the ship. Telescoping capability to reach nearly to the bottom of
the ship hold is required. Dead-boxes, as a retrofit control system, are
much more expensive than tents with aspiration. From an environmental view-
point the advantage is that dead-boxes can control emissions during all phases
of bulk carrier loading. They require careful operator attention to keep the
spout near the grain level and thus reduce emissions to below 20 percent
opacity. No special setup time or effort is required to initiate loading.
Typically, during bulk loading, some visible emissions may be present. Dead-
box systems do not control emissions from tween-deckers unless the trimming
device is modified so it can be connected to the aspiration system.
The costs of retrofit submerged loading systems are similar to dead-box
systems when major gallery modifications are required. These slanted spout
systems do not impose as great a demand on the gallery as a dead-box. There
may be cases where submerged loading retrofit costs could be much less than
dead-box costs. In fact, the submerged loading system in Seattle was orig-
inally designed to operate close to the grain pile, not submerged. No modi-
fications were required to use submerged loading at the Seattle terminal.
Other advantages and disadvantages of submerged loading are similar to dead-
box systems.
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SECTION 3
SITE INSPECTIONS AND VISIBLE EMISSION MEASUREMENTS
Rite Inspections were conducted for the purpose of observing tween-decker
and topping-off operations. Pertinent data which includes visible emissions,
loading rates, worker safety, control options, and other information was ob-
tained. Descriptions of site inspections follow.
TWEEN-DECKER LOADING AT UNITED GRAIN IN TACOMA, WASHINGTON
The United Grain Corporation shiploading facility in Tacoma, Washington
was visited on September 28 and 29, 1979, by GCA for the purpose of observing
the loading operations. 1 At the time of this inspection a 15,000 ton capacity
tween-decker cargo ship, the President Cleveland, was being loaded with corn.
Information obtained at this inspection helped to determine the extent of vis-
ible emissions generated during loading activities and aided in determining
whether suitable air pollution control equipment, particularly the tent as-
piration systems currently employed by the Bunge and Dreyfus facilities, can
be safely utilized to control emissions during the loading of a tween-decker.
Equipment
Loading of a tween-decker is more complicated than the loading of a bulk
carrier or self-trimmer due to the nature of the holds which contain horizontal
intermediate decks 10 to 20 feet apart surrounding the hatch. The horizontal
Intermediate decks extend from the side of the ship out into the hold approxi-
mately 20 to 25 feet. To prevent listing of the ship at sea it is extremely
important to fill the hold in such a manner that there are no empty spaces
underneath the intermediate decks.- To complete this task a device referred to
as a trimmer is employed to throw grain outward from the hatch to occupy the
space under the deck surrounding the hatch. The trimming device weighs approxi-
mately 2500 lb and Is lowered into the hold suspended by the ships fall. Flex-
ible metal spout extenders, which vary in legth from 20 to 60 feet, link the
spout from the gallery to the trimming machine located down in the hold (see
Figure 5).
Two to four operators remain down in the hold at the grain level during
trimming activities to operate the trimming device. The trimmer operators
secure the trimming device by attaching it with ropes to supporting structures
in the ships hold. Securing the device prevents it from moving due to the
nature of the machine to kickback powerfully in the opposite direction of the
emerging stream of grain. Once the trimmer is secure and the grain begins to
flow, the operators swivel the trimmer by bracing themselves against the
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device and adjusting the securing ropes to obtain the proper position with
respect to the ship hold. The elevation of the stream of grain emerging from
the trimmer is adjusted up or down by a hand crank control on the device or
by informing the boom operator to raise or lower the entire unit.
Trimmer Operating Procedures
The loading of a tween-decker involves a coordinated effort between the
boom, spout and trimmer operators. Each operator requires direction from the
other operators to complete his task. For example, the boom operator cannot
determine where grain is required under the intermediate decks from his van-
tage point at the boom control pannel. The boom operator relies on audible
and visual signals from the trimmer operators to help position the trimming
device in the proper location within the ship's hold. The loading spout must
be moved in conjunction with the trimmer device to prevent the flexible metal
extension on the spout from being detached from the trimmer. The spout opera-
tor is able to properly place the spout by observing the.movement of the trim-
ming device within the hold and by communicating with the boom operator. The
trimmer operators signal to the spout operator through audible and visual sig-
nals when they want the grain flow started and stopped. Data collected over
36 hours of trimming operations showed that the grain flow was interrupted
frequently. The average continuous running time was 11.3 minutes. The trim-
ming operation was then halted for an average of 6.4 minutes before trimming
was again resumed. Such intermitent loading is in part a result of the con-
tinual need for repositioning of the trimming device. The trimming device is
moved and resecured frequently to achieve even and complete filling underneath
the intermediate decks.
detachable
SPOUTS
Figure 5. Trimming a tween-decker.
15
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Worker Safety Assessment
The loading of a tween-decker is a relatively dangerous operation, par-
ticularly for the trimmer operators who must handle the 2500 lb device sus-
pended from the ships fall. As mentioned earlier, the trimmer has a powerful
kickback and could therefore strike trimmer operators if for any reason it
becomes unsecured. In addition, trimmer operators are in danger of being
struck by the massive device when the boom operator is repositioning the
trimmer. The trimmer is suspended on cables between two booms which makes it
difficult for the boom operator to manipulate it in the confines of the ships
hold.
The fact that trimmer operators must work on the surface of the grain
pile adds to the hazards involved in trimming a tween-decker. Trimmer opera-
tors work with the device while standing knee-deep in grain, often on the side
of a slopping pile. The poor footing hampers the maneuverability of the trim-
ming operators and increases the time required to retreat to safety should
the device get out of control. In addition to the poor footing, it appears
to be the nature of a grain pile being poured to slide to its angle of repose
in stages. In one instance a trimmer operator was observed to be buried up
to his waist due to a grain slide when only seconds before he had been only
knee-deep in the grain.
Suspended airborne dust within the ship hold adds to the dangers involved
in operating the trimming device. After several minutes of trimming, suspended
dust severely limits the visibility to a point where the trimmer operator's
ability to see the trimming machine, structures within the ship hold, and the
configuration of the grain pile are reduced significantly. Limited visibility
within the ship's hold also hampers communication between the trimmer operators
and the boom and spout operators on deck. Due to high noise levels during trim-
ming, the operators depend on visual signals to communicate which are often
difficult to discern when suspended dust reduces visibility. This produces a
potentially dangerous situation if the trimmer operator must urgently request
that the grain flow be stopped and/or the trimmer location be changed. In
addition, limited visibility may hamper rescue efforts if an accident occurs.
Ohservation of Visible Emissions
The subject facility did not empoly any air pollution control equipment
to abate emissions during loading of tween-deckers. The hatch covers were
fully opened which allows the particulate emissions to exhaust out of the hold
uncontrolled. At the time of this inspection the loading rate while trimming
was 375 tons/hr per spout which is half of the maximum capacity. The material
being loaded was corn which is generally considered, dustier than wheat although
longshoremen at the facility stated that the opacity of the particulate emis-
sions exhausting from the ships' hold were typical of particulate emissions
generated when loading wheat.
T.n accordance with EPA Reference Method 9, GCA determined the extent of
visual emissions generated from the trimming operation in order to determine
potential compliance with applicable regulations of the City of Portland.
16
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Visible emissions gent-rated during tlie loading of a twcen-deckc:r at the Bunge
and Dreyfus facilities in Portland, Oregon are assumed to be similar to the
visible emissions which were observed and recorded at the United Grain/Tacoma
facility since they have similar loading systems and tent aspiration pollution
control systems.
The visible emissions exhausting from the; ships' hold during trimming
operations were intermittent due to the intermittent nature of the grain flow.
There was a lag time of several minutes between the time when the grain flow
was started and visible emissions were observed and also between when the grain
flow was stopped and visible emissions were no longer evident. Consequently,
in the analysis of visible emissions, an interval of readings begins with the
first non-zero reading after the grain flow is started and ends with the first
zero reading after the grain flow is stopped.
An analysis of the visible emissions data recorded shows that the average
opacity for an interval of continuous readings varied between 34 percent and
12 percent and the maximum opacity in an interval of continuous readings varied
between 75 percent and 20 percent (see Table 1). Variations in opacity read-
ings are due to such factors as the duration of uninterrupted grain flow lo-
cation of the trimmer in the ships' hold, and fluctuation of winds at the deck
level.
Tlris loading operation would not comply with applicable regulations in
the City of Portland. The City of Portland is classified as a "special control
area" in which the regulation states that the opacity of visible emissions
must not be equal to or greater than 20 percent for more than 30 seconds in
any 1 hour (Oregon Administrative Rule 340-28-070). Fifty-six percent of the
visible emissions recorded were greater than or equal to 20 percent opacity.
BULK CARRIER LOADING AT THE LOUIS DREYFUS FACILITY
The Louis Dreyfus shiploading facility in Portland, Oregon, was visited
by CCA on October 1 and 3, 1979 for the purpose of observing the topping-off
of bulk carriers.Information obtained at this inspection has helped to de-
termine the extent of visible emissions generated and has aided in determining
whether suitable air pollution control equipment can be safely utilized to
control emissions during topping-off.
Equipment
Tlie facility has three slanted loading spouts, one of which is used at a
time. The spouts are about 15 meters (50 feet) long and can telescope about
6 meters (20 feet). To control emissions during the bulk loading phase, tar-
paulins or tents are placed over the hatch opening (see Figure 6). The tents
are approxiamtely 21 meters square (70 feet) and are made of light weight
plastic for ease in handling. The tents are stretched across the open hatch
and secured to the deck of the ship. The spout is attached to a hole in the
tent through which the grain is poured. Dust laden air contained underneath
the tent is exhausted by fan to a fabric filter collector through a flexible
aspiration hose about 15 cm (15 in.) in diameter. The aspiration hose hangs
17
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TABLE 1. SUMMARY OF VISUAL EMISSIONS RECORDED DURING UNCONTROLLED LOADING OF
A TWEEN-DECKER
Interval
number
Length of interval
(minutes)
Maximum
opacity
(percent)
Minimum
opacity
(percent)
Average
opacity
(percent)
Number of 30 second*
intervals > 20 percent
opacity
1
7
50
0
34
6
2
16
75
0
22
19
3
11
50
0
23
14
4
21
40
0
21
24
5
13
40
0
22
21
6
14
25
0
12
5
7
21
50
0
26
34
8
14
25
0
17
16
9
8
20
0
12
2
A
Indicates
potential violation
of Oregon
Administrative Rule
(340-28-070).
-------
Tent control system Topping-off operation
Figure 6. Grain loading operations at the Louis Dreyfus elevator.
-------
over the hatch combing down into the hold a length of between 1.5 m and 3 m.
The total capacity of the fabric filter is 875 m3/min (31,000 cfm) , however,
some of the air is drawn from transfer points. Air can be drawn from a hold
ut a rate of about 317 m3/min (11,000 acfm). If unused, aspiration hoses are
valved off. At the time of this inspection none of the unused aspiration
hoses were valved off.
For bulk loading, the procedure began by lifting the hatch covers over
the hold from 1/4 to 1/2 open depending on the type of cover. A typical
protocol was to position the loading spout and aspiration hose at one extreme
end of the open hold. The open portion of the hatch was then covered with a
tent. 'Die rate during bulk loading was 1000 tons/hr which is the maximum feed
rate that can be achieved. Loading continued at this rate until the grain
pile at the extreme end of the hold came to within 4 feet of the loading spout
(see Figure 7). At this time the grain feed was stopped and the tents were
taken off for the remainder of the loading operation. The hatch covers were
then pulled back the remainder of the way so the hold was completely open.
The loading spout was next moved to the center to continue uncontrolled load-
ing at .1.000 tons/hr. Loading continued approximately 45 minutes until the
grain pile approached the top of the hold. The corners and edges of the hold
were then filled to level out the load and to eliminate air spaces under the
sides of the hold or under the hatch covers. During this phase the loading
rate was cut back to .1/2 or 1/4 of full depending on how high the grain level
was to the top of the hold and the proximity of the loading spout to the edge
of the hold. The spout was moved around continuously during the final loading
stage so that the grain could be placed where needed to provide a level and
full load.
Visible Emissions
Visible emissions observations of two bulk carrier loading operations at
the Dreyfus facility were conducted by GCA in accordance with EPA References
Method 9 to determine the extent of visual emissions generated from the load-
ing of a bulk carrier, particularly during the topping-off phase, and to de-
termine compliance with applicable regulations of the City of Portland. Vis-
ible emissions generated during the loading of a bulk carrier at the Bunge
facility in Portland, Oregon are assumed to be similar to the visible emissions
which were observed and recorded at the subject facility since the Bunge and
Dreyfus facilities have similar loading systems and similar tent aspiration
pollution control systems.
Visible emissions from the hold during the bulk loading phase were min-
imal (1 ess than 5 percent opacity). The use of the tent aspiration pollution
control system abated emission almost completely with the exception of leaks
Ln the tent around the spout and at several other locations where the tent
was not securely fastened to the ships deck. Bulk loading at 1000 tons/hr
constituted approximately 65 percent of the total amount loaded in the hold.
Visible emissions from the hold during the topping-off phase (uncontrolled)
varied significantly with the loading rate (see Table 2). When the grain loading
20
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LOADING SPOUT
FLEXIBLE
ASPIRATION
HOSE
HATCH COVER
ANGLED
REPOSE =23°.
-V-V
COMBING
^v.-""." .
-V'^: ' •.I .V.•/ > ¦
—"' * 1"*'1- •: ¦
;:-v- ¦
Mxr*:¦ K-,;.; ;-,-K ^
.• •v.:.:' ¦
•' ';'"r v.'l
•: ' .V -f'..J'.-,' -V..% .V /.? V v;VV 'V
-¦ v.-.;:--;-r - :t "/.v5- •?. v--. •' > .:i": v,•.i'.c
AMOUNT LOADED
DURING TOPPING
OFF (UNCONTROLLED)
Figure 7. Side view of typical bulk loading procedure.
-------
rati; wan 1000 lonn/hr (lull rale) imii I :in I ohm were < > I > f :i.' r v
and 35 percent wlLh ail average opacity of 75 percent over the 23-minute ob-
servation period. At 250 tons/hr (1/4 full rate) the opacity varied from 35
to 20 percent with an average opacity of 28 percent over the 8-minute obser-
vation period.
TABLE 2. VISIBLE EMISSIONS GENERATED DURING T0PPING-0FF
OF A BULK CARRIED HOLD AT LOUIS DREYFUS
Loading Maximum Minimum Average Duration of
rate opacity opacity opacity observations
(tons/hr) (percent) (percent) (percent) (minutes)
1000 95 35 75 23
* 55 20 33 25
250 35 20 28 8
~
The loading rate varied between 500 tons/hr and
250 tons/hr.
The topping-off phase of the loading operation clearly does not comply
with applicable regulations of the City of Portland which is classified as a
"special control area." The regulation states that the opacity of visible
emissions must not be equal to or greater than 20 percent for more than 30
seconds Ln any 1 hour (Oregon Administrative Rule 340-28-070). The emissions
observed were greater than or equal to 20 percent during the entire topping-
oFf operation which generally lasts from 1 to 2 hours.
Amount Loaded During Topping-off
From previous discussions, it is obvious that the Oregon opacity regula-
tion cannot be met during topping-off. GCA, therefore, investigated the time
spent and quantities of grain introduced during this uncontrolled phase.
Values for the amount loaded during the uncontrolled topping-off phase
of two holds for which visible emissions data were obtained were provided by
the grain terminal operators. Uncontrolled loading amounted to 38 percent in
.one hold and 19 percent in another. Tents were removed, in both cases, when
the graLn at one end of the hold was within 8 ft of the top of the combing.
In the hold in which 38 percent of the grain was topped-off, the grain was
loaded until it was level with the top of the combing. In the second case
the grain was loaded only until it was level at 8 ft below the top of the
combing. If the latter hold had been filled to the top of the combing, the
amount loaded during topping off would have approached 40 percent.
Grain terminal operators and longshoremen involved in loading activities
were interviewed concerning the topping off procedures witnessed during these
Inspections. Each person interviewed indicated that the amount loaded during
uncontrolled topping-off was excessive and could be substantially reduced.
Operators at the Bunge and Dteyfus facilities stated that the amount loaded
22
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during topping-off could be reduced to a maximum of 25 percent of the total
amount loaded by more fully employing the tent aspiration pollution control
system.
Loading Problems
Grain terminal operators stated that it is not always possible during the
loading of bulk carriers to limit uncontrolled topping-off to 25 percent of
the total amount loaded in every hold.
Often bulk carriers are loaded such that one hold is not completely
filled (referred to as a slack hatch). The slack hatch is a center hold which
is filled with grain until the ship is at its required draft. The amount
loaded in this slack hatch varies from one-third to three-fourth of the hold
capacity. It is extremely important to load the slack hatch evenly to prevent
the ship from listing (loading evenly is mandated and enforced by the National
Cargo Bureau). The grain is loaded evenly by continually moving the spout
around the hatch, prohibiting the use of tenting during the entire operation.
There are occasions when the ship sits very low in the water such that
the grain loading spout, when fully extended, cannot reach the deck level.
During the filling of the last empty hold of a bulk carrier at the Dreyfus
terminal the distance from the deck level to the loading spout was approxi-
mately 15 feet. The tent aspiration control system was not employed due to
the complication of fitting the tent around the spout and hatch. Windy days
would further complicate the problem. However, officials at the Bunge facility
stated that under such conditions it is possible to drape the tent from the
spout to the hold opening provided a large enough tent is employed.
Grain terminal operators stated that it is extremely dangerous to employ
tent control system when bulk loading during periods of high winds since long-
shoremen could be blown into an empty hold or off the ship when attempting to
position the tent over the hold.
23
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SECTION b
TECHNICAL FEASIBILITY OF MEETING OPACITY REGULATIONS
BY CONVENTIONAL CONTROL SYSTEMS
Observations of shiploading operations at the Bunge and Dreyfus facilities
indicate that they are not currently able to comply with the State of Oregon
visible emissions standard for the City of Portland during the entirely of
tween-deckcr loading and during significant portions of bulk carrier loading.
Tliis standard states that the opacity of visible emissions should not be equal
to or greater than 20 percent for more than 30 seconds in a given hour.
Air pollution agency officials in other geographical areas which load
significant quantities of grain, which includes San Francisco, Toledo, New
Orleans and Norfolk, Va., were contacted to determine applicable pollution
control regulations and practices for the loading of grain. Currently avail-
able air pollution control options which would enable the Bunge and Dreyfus
facilities to meet the City of Portland regulations were investigated. Con-
trol options investigated include process modification and/or add on pollution
control equipment.
TENT ASPIRATION POLLUTION CONTROL SYSTEMS
The use of a tent aspiration pollution control systems to abate particulate
emissions from both tween-decker loading and topping-off operations was inves-
tigated. Capital costs associated with employing tent control at the Bunge and
Dreyfus facilities arc minimal since they currently employ such systems. The
technical feasibility of achieving compliance with the regulations for both
tween-decker and topping-off loading operations is described below.
Tent Aspiration Applied to Tween-Decker Loading
It does not appear to be reasonable to employ a tent aspiration air pollu-
tion control system to achieve compliance with the City of Portland opacity
regulations during tween-decker loading at the Bunge and Dreyfus shiploading
facilities due mainly to the increase in health and safety risks associated
with operating the trimming device. Placing tents over the hold would inter-
fere with necessary visible and audible communication between trimmer operators
in the hold and operators on the deck level of the ship. Spout operators rely
on audible and/or visible signals from trimmer operators in order to determine
when to stop and start the grain flow. Similarly, boom operators position the
trimming device within the hold by receiving audible and visual signals. Thus,
trimmer operators would be more likely to sustain injuries due to the uncoor-
dinated loading effort resulting from the use of tenting.
24
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The trimmer operators could possibly employ radios to communicate with
boom and spout operators if tenting was used during loading operations.
However, radios would add to the complexity of the operation. It is doubtful
whether trimmer operators would be able to properly use radios while operat-
ing the trimming device.
It is possible that the use of tenting would increase the concentration
of suspended particulates contained in the hold. The increase in suspended
particulates would further restrict the visibility of the trimmer operator,
make it more difficult for operators to breath, and thus increase the health
risks associated with operating the trimming device. Some longshoremen inter-
viewed stated that they would refuse to operate the trimming device in a hold
covered by a tent for safety reasons. The use of tenting would hamper rescue
efforts in emergency situations. Longshoremen on deck would not be able to
respond to an emergency if they are not able to follow the trimming activities.
Consequently, in order to safely load a tween-decker it is desirable to have
the hold completely open so that both the boom and spout operators are able
to see into the hold to monitor loading activities and position the trimming
device and spout accurately.
In addition to increasing health risks, the use of tenting would greatly
increase the time required to load a tween-decker. As described earlier (see
Site Inspection Section), it is the nature of a tween-decker loading operation
to have intermittent grain feed due to the necessity for repositioning of the
trimming device. The tenting would have to be removed before the spout and
trimming device suspended by the ships fall could be repositioned. Consider-
ing how often the trimming device is repositioned (an interval of uninterrupted
grain feed lasts only for an average of 11.3 minutes before the trimming de-
vice requires repositioning), .it is conceivable that the use of tenting would
triple the time required to load a tween-decker.
Conventional Pollution Control Systems Applied to Tween-Deckers
I
As was mentioned earlier in this section, it is not feasible to employ
tent aspiration control systems during tween-decker loading operations due to
health risks and increased loading times associated with tent control. In
addition, submerged loading and dead-box control systems have high capital
costs ($5 million per facility) which make these control options unreasonable,
although the ability of terminal owners to raise prices to cover increased '
costs and maintain profit margins has not been evaluated. Consequently, based
on the data collected and observations made during this study, it is not tech-
nically feasible to meet opacity regulations by conventional control options.
An option available to regulatory agencies is to grant terminals a variance
in which tween-deckers are not required to meet opacity requirements. The
State of Ohio EPA took this course of action in their proposed regulations which
exempt topping-off periods and tween-decker loading from particulate emission
regulations. As described in the following section (see EMISSION ESTIMATES
Section), uncontrolled tween-decker loading would result in emissions of
55 g/ton (0.11 lb/ton) which is approximately four times greater than bulk
carrier loading if topping-off is limited to 25 percent of the total amount
loaded.
25
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Contrary to the above approach, regulations could be promulgated which
make it Illegal to load grain Ln tween-decker ships at facilities which are
not able to control emissions. IE such action were taken, only those facil-
ities which have modifLed trimming devices to be used in conjunction with
dead-box control systems could legally load tween-deckers. Portland area
terminal employing tent control systems would not be able to load tween-
deckers which account for approximately 8 percent of the total number of
ships loaded. In addition to the United States, countries employing tween-
deckers Include Russia and Japan. The ramifications on the balance of trade
resulting from not allowing tween-decker loading have not been evaluated.
Tent Aspiration Applied to Topping-Off Operations
It does not appear to be technically feasible to achieve compliance with
the City of Portland opacity regulations during the entirety of bulk carrier
loading at the Bunge and Dreyfus facilities by employing a tent aspiration air
pollution control system. A tent control system is effective in controlling
emissions during the bulk loading phase (opacities of 0 percent can be achieved).
However, emissions generated during the topping-off phase are in excess of the
opacity regulations (opacities in excess of 20 percent are typical). As de-
scribed earlier (see Site Inspection Section), during topping-off tenting can-
not be used because the grain loading spout must be moved around the hold to
spread the grain evenly to ensure that when the holds is filled there will be
no air spaces under the sides of the hold or under the hatch covers.
Although tent control is not completely effective in meeting opacity regu-
lations during the entire phase of bulk carrier loading, the use of tent con-
trol systems at the Bunge and Dreyfus facilities appears to be a reasonable
control option when considering the high capital costs associated with retro-
fitting the present facilities with more effective dead-box or submerged load-
ing systems (described later in this section). However, the tent control sys-
tem must be used to the fullest extent possible to minimize particulate emis-
sions. In particular, tiie amount of particulate emissions generated during
bulk carrier loading can be reduced by minimizing the amount of grain loaded
in the topping-off phase.
The current practice of bulk loading at one end of a hold until the grain
pile approaches the top typically leaves more than 30 percent to be loaded
during topping-off (see Site Inspection Section).
By filling the lioLd with the grain pile in the center until the pile
reaches the level of the tent, it is calculated that the amount of grain
loaded in Clie topping-off mode can be reduced to about 15 percent. Grain ter-
minal operators expressed the view that 15 percent could be achieved on some
hold although on other holds topping-off would amount to appreciably more due
to such factors as shLp desigti, position of spouts with respect to the hold,
and the skill and cooperation of the longshoremen. It was consensus of grain
terminal operators at the Bunge, Dreyfus and Toledo, Ohio facilities that
Umlting topping-off to 25 percent of the total amount loaded was
reasonable. r' 17
26
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The State of Ohio EPA has jurisdiction over facilities in Toledo, Ohio
which have particulate emissions problems during shiploading which are similar
to the problems at the Bunge and Dreyfus facilities in Portland, Oregon.
ConHequuntly, Ohio F.PA has recently proposed particulate matter emlssLon stnn-
dardH for hIi J p 1 ond Ing operations as follows:1 5
For Shiploading Operations at Grain Terminals:
(a) Except during topping-off periods or during the loading of
tween-deckers or tankers, the covering of the hatches and
loading spouts with tarpaulin covers and evacuation of the
hatches to control equipment which is designed to achieve
an outlet grain loading of 0.030 grains per dry standard
cubic foot of exhaust gases; or
(b) The installation and use of control measures such as dead-
box or bullet-type loading spouts which are equivalent to
or better than the overall control efficiency of the mea-
sures described in paragraph (4)(a) of this rule.
To complement the proposed regulation the Ohio EPA has also proposed a
definition for topping-off which reads as follows:
"Topping-Off" Means that Portion of a Shiploading Operation at
a Grain Terminal during which:
(a) The top portion of a hold (not to exceed twenty-five per-
cent of the total volume of the hold) is filled with grain;
and
(b) The control of particulate emissions through the use of
tarpaulin covers and associated ventilation and control
equipment is impractical or impossible.
The figure of 25 percent of the total volume of the hold not to be ex-
ceeded during topping-off was agreed upon in mediation between the City of
Toledo APC Agency and Port of Toledo grain terminal operators.
For a proposed regulation which limits topping-off to be effective in
reducing particulate emissions the regulation must be enforceable. The
State of Ohio EPA has not yet determined an enforcement system, but state
officials stated that they may enforce the regulation through a permit syste.
Under this system, grain terminal operators will be required to record the
amount loaded during the topping-off phase (uncontrolled) and submit data to
the APC Agency on a bimonthly or monthly basis. In addition, permit systems
could be supplemented by conducting site inspections at which violations (an
amount more than 25 percent of the total amount loaded during topping-off)
could be determined through observations.
27
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Ki'il m; i ii)', I In.' I o.kI i 11 j>_ r;ilf is a 1 so .in iT f cc I: i vc means of reducing parti-
culate i: in i sslon:; . Typically, operators load at full rate until it is neces-
sary to reduce the grain feed as the grain pile approaches the top of the
hold. Uncontrolled loading at the full loading rate (1000 tons/hr) produces
visible emissions for which the average opacity is 75 percent. However, if
good bulk loading practices are employed and all that remains to be topped off
are voids at the corners and edges of the hold. At this rate, visible emis-
sions are substantially reduced to an average opacity as low as 28 percent.
Also, if an attempt is made to keep the grain.spout close to the grain
pile, topping-off emissions could be further reduced. Facilities would pro-
bably still be in violation of the City of Portland regulations although vio-
lations would not be flagrant. Officials at the Bay Area Air Pollution Con-
trol Agency stated that by employing good bulk carrier loading procedures and
cutting back the loading rate to one-fourth of the full grain flow during
topping-off, grain terminals employing tent control are able to achieve com-
pliance with local regulations (opacity of visible emissions not greater than
or equal to 20 percent) although occasional violations of the regulations
have been cited.
DEAD-BOX CONTROL
A dead-box control system is very effective in controlling emissions at
shiploading operatLons (see Background Section). However, Kenneth Pacquer
of Marshall. Barr & Pacquer Inc., a designer of shiploading facilities familiar
with the Bunge and Dreyfus facilities, stated that the present galleries would
not support the additional weight and torque of a dead-box control system.20
Major modification to tlie gallery and perhaps even to the loading dock would
be required.
The capital costs associated witli retrofitting a dead-box loading system
at the Bunge and Dreyfus facilities would be about $1 million per loading
spout. Thus, depending on the number of loading spouts to be converted, the
costs oP installing dead-boxes would approach $5 million per facility.
A cost of 5 million dollars for refurbishing a gallery to allow the use
of dead-boxes, if amortized over a period of 15 years at 15 percent interest,
would amount to about 850,000 dollars per year. The grain throughputs of
Portland terminals vary from year to year, and from terminal to terminal, but
are typically about 1,000,000 metric tons per year. Thus, the cost of major
refurbishments amortized over 15 years would amount to about 0.85 dollars per
metric ton of grain shLpped or 2.3 cents per bushel. The average profit for
grain terminals is only 2.1 cents per bushel. The ability of grain elevator
owners to increase grain prices, currently $4 to $5 per bushel, to maintain
profit margins i.s not within the scope of this study.
SUBMERGED LOADING CONTROL
A .submerged loading system, in which the bottom of the loading spout is
actually buried below the grain level in the hold, is effective for control-
ling emissions from shiploading operations (see Background Section). However,
28
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in conversation with designers tJF sliiploading facilities famllLar with the
Bunge and Dreyfus faci]ities, it was determined that retrofitting those facil-
ities would require major modifications to the gallery and perhaps even to
the loading dock.20
First, the present galleries were not overdesigned and, therefore, could
not handle the weight and torque of additional aspiration tubes and telescop-
ing spouts. In addition, the present height of the galleris at both the
Bunge and Dreyfus facilities (60 feet) would not be sufficient for the falling
grain to acquire sufficient kinetic energy to push its way out of the bottom
of the spout. The spouts would then become plugged, producing a potentially
dangerous situation in which additional weight and torque would be put on the
gallery. Also, grain can back up in the gallery delaying the loading schedule.
It is believed that in order to provide sufficient kinetic energy to the grain
falling down the chute, the gallery must be at least as high as the gallery at
Cargill-Seattle (100 feet) which employs submerged loading. Even with the
100-foot gallery at Cargill-Seattle, the loading spouts plug occasionally
which necessitates removing the spout from the grain pile with resulting un-
controlled emissions.
A gallery higher than 60 feet would also be necessary in order to manipu-
late the longer spounts required in submerged loading. The large arc re-
quired to move the spouts from the dock to the ship's hold would prohibit the
use of submerged loading with the present galleries. When fully extended, the
spouts required for submerged loading would be double the length of those
currently used at the Bunge or Dreyfus facilities.
Finally, when considering major modifications to the Bunge and Dreyfus
facilities, dead-box control is a better choice than submerged filling due to
particulate control and efficiency of loading.
It is estimated that the capital costs of retrofitting submerged loading
systems at the Bunge and Dreyfus facilities would approach the costs of retro-
fitting dead-box control, about $1 million per loading spout. Considering
these high costs it is questionable whether installation of submerged loading
at the Bunge and Dreyfus facilities would be a technically feasible control
option although the ability of terminal owners to adsorb these costs has not
been evaluated.
29
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SECTION 5
EMISSION ESTIMATES
Estimates of emissions at the Bunge and Dreyfus facilities can be calcu-
lated using emission factors for tent controlled loading. As previously dis-
cussed (see Technical Feasibility of Meeting Opacity Regulations), tent con-
trol is likely to be the only cost effective control option available for emis-
sions at the Bunge and Dreyfus facilities. Emissions estimates calculated
using current topping-off procedures and improved topping-off procedures lim-
iting topp'ing-off to 25 percent of the total amount loaded are given below.
Emission estimates for dead-box and submerged loading are provided for
comparison.
In a prior study by GCA entitled Particulate Emission Factors and Fea-
sibil i.ty of Emission Controls for Shiploading Operations at Portland, Oregon
Grain Terminals, total and respirable concentrations were measured in dust
clouds generated during shiploading.1 The concentration, along with esti-
mates of cJoud cross-sectional areas and wind velocities, were used to esti-
mate particulate emission rates of shiploading operations. The estimated
emission rates have been used to develop emission factors for various phases
and types of shiploading (see Table 3).
TABLE 3. AVERAGE PARTICULATE EMISSION FACTORS
Emission factors (g/ton)
Process
Total Suspended Respirable
Uncontrolled loading
55
AO
5.8
lent controlled loading
Average
0
55
14
0
40
10
0
5.8
1.5
Deadhox controlled loading
Well operated
Poorly operated
0.3
2.8
1'. 2
2.4
0.04
0.14
it
EmLssion factors for tween-decker loading are the same as
uncontrolled loading.
'Note that only about 25 percent of the, total grain loaded
is loaded during the topping-off phase.
30
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These emission factors, which are based on emission measurements, differ
from past emission factors published in AP-42 by aout one order of magnitude.21
The past cmJfi.sion factor of about 5000 g/ton (.1 lb/ton) was estimated by sam-
pling tlu: ,'iHp I rat Ion from n submerged loading nystom. Since It Is quest ionab] v.
whether the particul ate concentraL Ion In the aspirated air Is typical oT dust
clouds exhausting from a ship's hold during uncontrolled loading, GCA's emis-
sion factors are used for this study.
The majority of the ships loaded at the Bunge and Dreyfus facilities are
bulk curriers. An analysis of 1978 data showed that the percentage of tween-
deckers loaded at these facilities was 8 and 7 percent, respectively. However,
due to their smaller capacity (an average tween-decker has a capacity of
10,000 tons compared to 20,000 tons for a bulk carrier), the amount of grain
loaded on tween-deckers amounts to only 3.5 to 4.0 percent of the grain loaded
annually. Tween-deckers are older ships which are used more extensively
during trading with foreign nations without provisions for reimbursement when
such ships are pulled out of dry dock to comply with the Cargo Preference Act,
Public Law 664. This law states that 50 percent of all grain furnished to
foreing countries without reimbursement must be moved on American ships. Few,
if any, tankers are used to carry grain in Portland and emissions are easily
controlled by placing an aspiration hose in the hatch opening.
The overall emission factors for bulk carrier loading with tent control
can be estimated by taking the average of the emission factors for uncon-
trolled and controlled loading, weighted by the amount of grain loaded during
bulk filling and topping-off for a typical hold. Limited data based on ob-
servations of topping-off operations showed that 20 to 40 percent of the hold
is currently filled without tents. Consequently, emission factors for cur-
rent loading practices would vary between 11 and 22 g/ton for total
particulates.
However, it is the consensus of opinion that by using good topping-off
procedures the percentage of the hold filled without tents could be limited
to not more than 25 percent for which the average particulate emissions fac-
tor is 14 g/ton (0.031 lb/ton) for total particulates, 10 g/ton (0.022 lb/ton)
for suspended dust and 0.003 lb/ton for respirable dust.17'18 Emissions re-
sulting from completely uncontrolled loading would result in emissions approxi-
mately four times greater (see Table 3). Emission factors for tent controlled
loading limiting topping-off to 25 percent are 50 times greater than those for
dead-box control when the dead-box is well operated.
Emission factors for tween-decker loading are considered to be the same
as emissions factors for uncontrolled loading which are 55 g/ton (0.12 lb/ton)
for total particulates, 40 g/ton (0.088 lb/ton) for suspended, and 5.8 g/ton
(0.013 lb/ton) for respirable dust. Assuming 4 percent of the total amount of
grain at the Bunge and Dreyfus facilities is loaded on tween-deckers and the
remaining 96 percent is loaded in bulk carriers, the overall average emission
factor for total particulates generated during sfyiploading is calculated to
be 15.6 g/ton (0.034 lb/ton). Therefore, tween-decker loading accounts for
approximately 14 percent of the total emissions at the Bunge and Dreyfus
facilities.
31
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.1.
2
3
4
5
6
7
8
9
10
LI
1.2
REFERENCES
Battye, W. , and R. R. Hall. Grain Terminal Control Study. Volume I.
Particulate Emission Factors and Feasibility of Emission Controls for
Shiploading Operations at Portland, Oregon Grain Terminals. GCA/Tech-
nology Division. GCA-TR-79-06-6(1), EPA Contract 68-01-4143, Task
Order Nos. 24 and 47. Final Report. June 1979.
Standards Support and Environmental Impact Statement, Volume I: Proposed
Standards of Performance for the Grain Elevator Industry. U.S. Environ-
mental Protection Agency. EPA-450/2-77-001a. February 1977.
Conversation with Mr. J. Faherty, Bunge Terminal Grain Elevator in
Portland, Oregon. October 1979.
Conversation with L. Harper, Louis Dreyfus Terminal Grain Elevator in
Portland, Oregon. October 1979.
Oregon Administrative Rules, Chapter 340, Division 21, Department of
Environmental Quality, Air Pollution Control.
Inspection of the Bunge Terminal Grain Elevator in Portland, Oregon.
January 1978.
Inspection of the Louis Dreyfus Terminal Grain Elevator in Portland,
Oregon. January 1978.
Inspection of the United Grain Terminal in Tacoma, Washington.
November ,1978.
Battye, W., R. R. Hall, and P. Oilienfeld. Grain Terminal Control Study,
Volume II, Grain Dust Levels Caused by Tent Control of Shiploading Com-
pared to Minimum Explosive Limits. GCA/Technology Division. CCA-TR-79-
06 (02). EPA Contract No. 68-01-4143, Task Order Nos. 24 and 47. Draft
Report. May 1978.
Conversation with Mr. J. Close, Oregon Department of Environmental
QualLty. January 1978'.
Inspection of the Cargill Terminal Grain Elevator in Portland, Oregon.
January 1978.
Inspection of the Continental Grain Terminal in Tacoma, Washington.
January 1978.
32
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L'J. .Inspection of Llie* Cargii.I Grain Elevator in Seattle, Washington.
January 1978.
14. Telephone Conversation between Mr. D. McLaine of Archer Blower Co.
(designers of the particulate omission control system in use at Cargill
in Seattle) and W. Battye (GCA/Technology Division). 10 January 1978.
15. Inspection of Tween-Decker Loading at United -Grain Terminal in Tacoma,
Washington. September 1979.
16. Inspection of Topping-Off Operations at the Louis Dreyfus Terminal in
Portland, Oregon. October 1979.
17. Conversation with Mr. F. Wolf, The Andersons Grain Terminal in Maumee,
Ohio. October 1979.
18. State of Ohio EPA Proposed Rulemaking Concerning Particulate Matter
Emission Standards. Public Hearing September 26, 1979.
19. Conversation with Mr. J. Orlemann, State of Ohio EPA in Columbus, Ohio.
September 1979.
20. Conversation with Mr. K. Pacquer of Marshall Barr & Pacquer Inc.
(designers of Grain Loading Terminals). September 1979.
21. Compilation of Air Pollutant Emission Factors. Third Edition.
U.S. Environmental Protection Agency. Publication No. AP-42.
August 1977.
33
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A I'I'END l.X A
TABLE A-l. CONVERSION FACTORS FOR SELECTED
METRIC AND BRITISH UNITS
To convert from
To
Multiply by
g (grams)
8
pm (micrometer)
cm (centimeter)
m (meter)
m2
m3
g/m3
g/m3
m/min
in3 /mi n
gr (grain)
lb (pound)
in. (inch)
i n
Tt (foot)
rt2
rt3
gr/rt3
lb/ft3
ft/min
f t3/mui
g/t (metric ton) lb/ton (British)
15.432
0.0022
0.000254
2.54
3.281
10.76
35.32
0.437
¦0.000062
3.281
35.32
0.002
34
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APPENDIX B
CARGO PREFERENCE ACT
August 2t>. 1954
[S. J2.11)
Public Law 664
CHAPTER936
AN ACT
To amontl tin? Merchant Marine Act. to i>i*i»\ n 1»- prnuunent legislation
for the trai»>|>ortiilion of u ^wbstuutinl portion > t watcrfooine cargoes in
United Stah'sliag vessels
U . 3.
v#s««la.
C n r g
enct.
49 Stat. 2015.
46 USC 1241.
1 S USC 6 i fi«
He. it, enacted hy the 'Senate (aid flou-ie of Representatives of the
irehont J'-njted State* of America in Cirmjreni usxewhied, That section 901
prrfer- <>f the Merchant Marine Act, l'.WIi, as amended, is hereby amended
hy inserting "(a)'' after "Skc. DDL" and hy adding at the end of the
section the follow my new Mil»ection :
"(h) whenever the Tinted States shall procure, contract for, or
otherwise obtain for its own account,, or shall furnish to or for the
account of any foreign nation without provision for reimbursement,
any equipment, materials, or commodities, within or without the
United States, or shall advance funds or credits or guarantee the con-
vertibility of foreign currencies in connection with the furnishing of
such equipment, materials, or commodities, the appropriate agency
or agencies shall take such steps as may be necessary and practicable
to assure that at least 50 per centum of the gross tonnage of such
equipment, materials, or commodities (computed separately for dry
bulk carriers, dry cargo liners, and tankers), which may be trans-
ported on ocean vessels shall be transported on privately owned
United States-flag commercial vessels, to the extent such vessels are
available at fair and reasonable, rates for United States-flag commer-
cial vessels, in such manner as will insurt a fair and reasonable par-
ticipation of United States-flag commercial vessels in such cargoes by
geographic areas: Provided, That the provisions of this subsection
may be waived whenever the Congress by concurrent resolution or
otherwise, or the President of the United States or the Secretary of
Defense declares that an emergency exists justifying a temporary
waiver of the provisions of section 901 (b) and so notifies the appro-
priate agency or agencies: And -provided further, That the provi-
sions of this subsection shall not apply to cargoes carried in the ves-
sels of the Panama Canal Company. Nothing herein shall repeal or
otherwise modify the provisions of Public Resolution Numbered IT,
Seventy-third Congress (48 Stat. 500), as amended."
Approved August 26, 1954.
35
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