DISPOSAL OF SOLID ALUMINUM PROCESS WASTES
IN THE OCEAN
by
D» J, Baumgartner
R. J, Callaway
G. R. Ditsworth
National Coastal Pollution Research Program
Federal Water Pollution Control Administration
Pacific Northwest Water Laboratory
200 S. 35th Street
Corvallis, Oregon 97330
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CONTENTS
I Introduction ....I...,,....*..*....*... 1
II Material and Dumping Schedule ...,...«. 1
III Pollutional Aspects ....», 6
IV Possible Pollution Problems
A En Route .,.....,...., 7
B At Ocean Disposal Site .„.,......, 8
1 Transport with Current 10
2 Bottom Accumulation 11
V Summary and Recommendations 13
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Disposal of Solid Aluminum Process Wastes
in the Ocean
I, Introduction
Reynolds Aluminum Company, Longview, Washington, has requested
permission from the Portland District, U. S. Army Corps of Engineers,
to dump solid aluminum process wastes at one of three localities in the
Pacific Ocean near 125° W. longitude, 46° N. latitude. These sites
are approximately 40 miles off the mouth of the Columbia River and are
shown on Fig. 1, which is an overlay from U.S.C.G.S. chart no. 6002.
This report discusses the probable disposition of the material to
be dumped.
II. Material and Dumping Schedule
One-hundred seventy-five thousand tons of accumulated material,
Kelly residue, is to be dumped at a rate of 1000 tons per day within
a one-year period beginning about July 1, 1968. This material is
generated at the rate of 18,000 tons per year and the company proposes
to dump each annual accumulation within a one-month period.
In addition to the Kelly residue, the company wishes to dump another
material, lime mud, generated at the rate of 8,600 tons per year, within
an 8-day period each year at the 1000 tons per day rate.
Detailed chemical and physical characteristics of each material
as provided by the Corps of Engineers are given in Tables 1, 2, and 3.
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TABLE 1
DESCRIPTION OF WASTE MATERIALS
Chemical
Component
Carbon
Water
A12°3
CaF2
Fe2°3
SiO,
Material:
Analysis
Wt. 7,
35
12
35
3.5
8
1.5
5
Kelly Residue
Sieve
Tyler Mesh
65
100
150
200
Pan
Size
Cum, 7« Retained
6.0
13.7
22.6
29.3
100
Particle Density: 168 pounds per cu. ft. (Sp. Gr. - 2.7)
Settling Rate: 3.5 feet per hour in calm sea water at 50°F.
Location of Stockpile: SE end of Reynolds Metals Company
property, Longvlew, Washington, between spurs of Northern
Pacific Railway
Size of Stockpile as of 7-1-67: 175,000 tons
Rate of Generation: 18,000 tons per year
Proposed Dumping Schedule: 1,000 tons per day; 20,000 tons per
month until stockpile is depleted, beginning about 7-1-68
and ending about 7-1-69. Thereafter, the annual generation
of 18,000 tons can be disposed of in less than one month at
1,000 tons per day.
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TABLE 2
KELLY RESIDUE
LABORATORY ANALYSIS
WEIGHTED VALUES
Sample
1
2
3
4
5
6
7
8
9
10
11
12
13
CN~,
Total
1.06
1,78
2,20
1,63
1.67
6.38
3.12
4.44
29.48
3.52
2.68
1.65
1.10
ppra
Free
0.89
1,23
1.94
0.62
0,59
0.84
0.90
3,10
13.38
0.66
1.32
0.57
0.53
Area
Represented,
Sq» Ft.
9,375
8,200
7,025
7,250
15,025
10,000
10,000
10,010
10,060
10,000
14,625
10,125
7,850
Fraction
of
Total
Area
0.0675
0.0590
0.0506
0.0522
0.1082
0.0720
0.0720
0,0721
0,0724
0.0720
0.1058
0.0729
0.0565
Weighted Values,
ppm CM"
Total Free
0,07155 0.06008
0.10502 0.07257
0.11132 0.09816
0,08509 0,03236
0.18069 0,06384
0.45936 0.06048
0.22464 0.06480
0.32012 0.02235
2.13435 0.96871
0.25344 0.04752
0.28354 0.13966
0,12028 0.04155
0.06215 0,02995
(Avg. 14-
17 to find
A)
14 103.07
15 98.12
16 78,50
17 2.47
Avg., A 70,54
Sura of 1-13+A
47.89
44.48
49.87
0.57
35.70
9,375
138,920
0.0675
1.0007
4,76850
9,18
2.41330
4,12
Total
Free
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TABLE 3
DESCRIPTION OF WASTE MATERIALS
Material: Lime Mud
Chemical Analysis Sieve Size
Component Wt. % Tyler Mesh Cum. % Retained
CaC03 90 65 4.4
CaF2 10 100 16.4
100 150 53.8
200 88.7
Pan 100.0
Bulk Density: 88 pounds per cu. ft.
Particle Density: 187 pounds per cu. ft. (Sp. Cr. = 3.0)
Settling Rate: 3.7 feet per hour in calm sea water at 50°F.
Location of Stockpile: Immediate east of Kelly Residue stockpile
Size of Stockpile: zero, as of 7-1-67
Rate of Generation: 8,600 tons per year
Proposed Dumping Schedule: 1,000 tons per day for eight con-
secutive days each year, beginning about 7-1-68, not on the
same days that Kelly Residue is dumped.
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Ill, Pollution Aspects
The cyanide portion of the Kelly residue appears to be of major
concern from pollutional considerations. Little information concerning
tolerable concentrations in sea water has been found. However, McKee
and Wolfe (1963) cite opinions of various investigators that wastes
should not be discharged to ocean waters when the resulting HCN con-
centrations will exceed 0.05 mg/1. This concentration is equivalent to
,,0488 mg/g in sea water at 32°/oo salinity and 10°C. Cyanide ions in
water react, depending on the pH of the system, to form undissociated
hydrogen cyanide (HCN). Since this is the form in which the ion is
the most toxic, it is appropriate to consider toxicity expressed in
relation to the HCN concentration. At a pH of 8, approximately 6»7%
is in the form of a cyanide ion (CN~).
We will presume for the purpose of this analysis that this is to be
the maximum allowable concentration of HCN in the area of the discharge
of the waste materials. Table 2 shows that the weighted average con-
centration of free cyanide ion in the accumulated stockpile of Kelly
residue is 4.12 parts per million. However, because of the rather large
variability in the analyses of the various sections of the stockpile,
we would prefer to use for this analysis the average of four analyses
in one section of the stockpile which amounted to 35,7 ppm of free CN"o
While this is a considerable over-estimate for the pollutional aspects
of the stockpile as a whole, it is not unreasonable to use a value this
high to represent possible hazardous conditions of any one particular
large load of residue. A 1,000 ton barge load would then contain
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71,4 pounds of free CN". The equivalent in terras of HCN would be 74
pounds „
IV. Possible Pollution Problems
A. Enroute
Chip barges in the Yaquina River, petrochemical tankers in the
Ohio River, and chlorine barges in the Mississippi River have suffered
accidental spills or been sunk, with subsequent release of the material
to the waterway. There is a distinct possibility that the same type of
accident could occur with the transport of the Kelly residue material
down the Columbia River to its ultimate disposal site in the ocean.
The resulting pollution problem would appear to be more serious for
this situation than that resulting from the intentional dumping of the
barge at the disposal site. Assuming a relatively low flow of the
Columbia River of 123,000 cfs, the uniform distribution of a sunken
barge load of 1,000 tons over a period of one hour would produce a
concentration of suspended solids of 86 mg/1. Similarly, the concentra-
tion of HCN would be about three mg/1.
A more appropriate and precise analysis is provided by a
mathematical model of the lower Columbia River considering the effects
of diffusion as well as advection and considering that the barge contents
would probably be dissolved and redistributed over a much longer period
of time. The resulting pollution problem would be most serious at Long-
view, Washington, and would diminish as the accident site approached the
ocean. Unfortunately, the limit of our mathematical model at present
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is mile 20, and the analysis is carried out for an accidental spill at
that location.
Assuming that the barge contents are distributed uniformly for
a day and confined to the flow through the south channel of the river
(see figure 2) the suspended solids concentration would be about four
mg/1, and the concentration of HCN would be about .14 mg/1.
Under similar conditions, but assuming the complete flow of the
Columbia River participates in the distribution of the wastes, the con-
centration would be about .6 mg/1 of solids and .02 mg/1 of HCN.
Because of the rapid flushing of the Columbia River at this
point, these concentrations will be localized to within a few hundred
square meters for a period of 1 to 2 hours.
B, At Ocean Disposal Site
Currents in the area are poorly defined and influenced by wind
and local bathymetry. Generally, surface currents are northerly in
the winter and southerly in the summer. Average velocities of these
currents vary from 10 to 20 cm/sec and 5 to 20 cm/sec respectively.
(Budinger, Coachman and Barnes, 1964).
Stevenson (1966), using parachute drogues, measured subsurface
currents off Newport, Oregon from 1962 to 1965. Mean current velocities
in this area were found to be 9.9 cm/sec at 0-10 meters depth, 6.2
cm/sec at 40-60 meters depth, 4.8 cm/sec at 75/150 meters depth and
6.2 cm/sec at 200-250 meters depth. The mean direction of these
currents was south-southeasterly.
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No specific information has been found about the nature of the
current at the much greater depth found at the suggested disposal site.
The current regime on the ocean floor will have an effect on the
accumulation of solids if they reach the ocean floor due to sedimenta-
tion, while the surface currents will have an effect on the initial
distribution of the material as it is dumped from the barge.
1. Transport with Current
When the barge contents are discharged at the disposal
site, possible pollution problems may result if the material is finely
divided and evenly distributed so that the relatively high surface
currents will transport the material, perhaps toward the beaches. If
for some reason all of the CN" were dissolved by the surface waters and
retained in the top two meters, distribution over 360,000 square meters
would be required to reduce the potential HCN concentration to below
5 mg/1. This represents a circle of radius 340 meters. This is the
result which might be expected if sedimentation were governed by the
individual particle settling rates as indicated in Tables 1 and 3.
However, this behavior is not expected, as the material most probably
will be compacted into various size clumps. While there is no exact
method of analysis for the resulting sedimentation rate, guidance can
be provided by considering two cases which represent the range of
likely situations. One is to assume the material is a slurry and
settles like a liquid of the same bulk density; the other is to assume
all of the barge contents act as a single clump of material which
settles in a discrete fashion.
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Assuming the material acts as a slurry, it will initially
settle with a high velocity due to the large volume of dense material,
As it proceeds downward the turbulent boundary between the slurry and
the ambient sea water will cause mixing of the two and the creation of a
wide9 less dense, "cloud" of slurry. As the cloud continues to
settle, it will be further diluted by sea water and will decelerate-
At a depth ZMAX the cloud will become so dispersed, and the downward
velocity will be so degraded, that settling will be determined by the
mechanics of the individual discrete particles. ZMAX has been cal-
culated to be 390 meters, and the calculated time of travel to this
depth is 99 seconds, according to the method of Morton, Taylor and
Turner (1956),
If, on the other hand, the mass acts as a large discrete
particle, it will fall with a constant velocity through the water
column until reaching the bottom pass ZMAX in 16.5 seconds. Its
average settling velocity will be 23«6 cm/sec.
In reality, the material will probably settle in an inter-
mediary fasion between the two discussed,
Surface currents have the most effect in the cloud analysis,
causing increased dilution, and will possibly transport some particles
away from the main flow of the cloud, which would remain essentially
vertical,
2, Bottom Accumulation
If the barges can dump within a one-mile radius of the desired
dumping location, the most concentrated possible result on the bottom
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will be an accumulation of solids with a one-mile radius. Under
this assumption the present stockpile of Kelly residue would be
represented by an average area distribution of 43 pounds per square
meter. The annual production of residue would result in an accumula-
tion of 4 pounds per square meter per year and the lime mud would add
another two. If the annual accumulation of 18,000 tons of Kelly
residue and 8,600 tons of lime mud were completely dissolved and/or
suspended at any one time over this same area, to a depth of one
meter, the concentration would be about 3000 mg/1. (Assuming a free
cyanide ratio of 20 micrograms per gram, the concentration of HCN
would be very near the maximum recommended allowable.) Considering
the fact that distribution over another meter would reduce the con-
centration to one half this value, plus the extreme possibility
against its occurrence in the first place, it seems unlikely that a
dangerous situation regarding the solids would exist. In considering
the HCN danger, it should be pointed out that the concentration would
be reduced in time by bacterial decomposition.
According to Fair and Geyer (1954), deposited solids may be
lifted from the bottom and transported if theoverlying water has a
velocity above a critical value dependent on grain size, frictional
resistance, and cbheSiveness of the particles. With some assumptions
a value of 7,3 cm/sec was computed for an estimated mean grain size
of 0,02 mm» The fact that the bottom is much lower than the edge of
the continental shelf (80-90 fathoms) in this area (Carlson, 1968)
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suggests that even if currents of this magnitude occur, scoured
bottom material would be subject to considerable additional impediments
to transport toward the beach (Sverdrup, Johnson and Fleming, 1942)»
Merely as a point of reference, it is noted that New York
city disposes of 175,000 tons of sewage sludge annually, by barging to
a disposal area 13 miles east of New York Harbor, where the water
depth is 30 meters.
IV. Summary and Recommendations
The analysis at hand indicates that acute pollution problems are
not likely to occur at the dumping site, but that a short-term prob-
lem may arise due to the high HCN concentration associated with an
accidental spill of a barge in the Columbia River. Similar disposal
situations have not been sufficiently studied to allow precise deter-
mination of the fate of the solids or prediction of long-term pollu-
tional effects. In this light the following recommendations are
offered:
1) Based upon computed settling rates and apparent effect of hori-
zontal dispersion by currents, it appears that proposed dump site two
would be the most favorable. It is in water approximately 900 fathoms
(1647 meters) deep and near the mouth of Willapa Canyon, which will
cause deep settling material to be funneled further seaward. Also, it
is further from the continental shelf than either site one or three.
If possible, this recommendation should be reviewed after a hydrographic
study to ascertain bottom currents in the area.
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2) The CN" content of each barge load should be determined before
departure,
3) Each barge voyage should be forecast and accidental groundings
or spills reported to an appropriate monitor.
4) Further study of the sedimentation mechanics of this type of
disposal method should be supported with special emphasis on prototype
studies,
5) Additional evidence should be sought on the long-term biological
effects of low HCN concentrations in sea water.
6) Any permit to dump should be subject to review on the basis of
additional evidence provided by the studies recommended.
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References
Budinger, T. F., L. K. Coachman, and C. A. Barnes. 1964. Columbia
River Effluent in the Northeast Pacific Ocean, 1961, 1962: Selected
Aspects of Physical Oceanography. Technical Report No. 99,
Department of Oceanography, University of Washington, Seattle, 78 p.
Carlson, P. R. 1968. Marine Geology of Astoria Submarine Canyon.
Ph.D. thesis. Oregon State University, Corvallis. 259 p.
Fair, G. M., and J. C. Geyer. 1954. Water Supply and Waste Water
Disposal. Wiley, New York. 973 p.
Morton, B. R., Sir Geoffrey Taylor, and J. S. Turner. 1956. Turbulent
Gravitational Convection from Maintained and Instantaneous Sources.
Proc. Royal Soc. London. Ser. A., 234: pp. 1-23.
McKee, J. E. and H. W. Wolfe. 1963. Water Quality Criteria. State
Water Quality Control Board, State of California, Sacramento.
548 p.
Stevenson, M. R. 1966. Subsurface currents off the Oregon Coast.
Ph.D. thesis. Oregon State University, Corvallis. 140 p.
Sverdrup, H. U., M. W. Johnson, and R. H. Fleming. 1942. The Oceans.
Prentice Hall, Englewood Cliffs, N. J. 1087 p.
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