ISSUE PAPER:
Regulating Cadmium and Mercury
in Drilling Fluid Discharges
-------
EPA Contract No. 68-01-6815
Work Assignment No. 4
ISSUE PAPER:
REGULATING CADMIUM AND MERCURY
IN DRILLING FLUID DISCHARGES
May 8, 1984
Prepared for:
U.S.Environmental Protection Agency
Office of Regulations and Standards
and
Office of Water Enforcement and Permits
Prepared by:
Technical Resourcces, Inc.
10215 Fernwood Road, Suite 408
Bethesda, MD 20817
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CONTENTS
ISSUE PAPER ON REGULATING Cd AND Hg LEVELS
IN BARITE/DRILLING FLUIDS 1
ISSUE: TECHNOLOGIC FEASIBILTY 2
ISSUE: IMPROVEMENT 3
ISSUE: ENVIRONMENTAL IMPACT 4
APPENDICES
APPENDIX A.
APPENDIX B.
APPENDIX C.
APPENDIX D.
APPENDIX E.
APPENDIX F.
APPENDIX G.
Summary of Laboratory Studies on Metal Bioaccumulation
Following Exposure to Drilling Fluids
Summary of Field Studies Describing Sediment Metal#
Distributions Resulting from Discharges of Drilling
Fluids and Cuttings
Summary of Field Studies or Studies In Situ Describing
Metal Bioaccumulation Following Exposure to Drilling
Fluids and Cuttings
Summary of Cadmium and Mercury Content in Generic
Drilling Fluids
Cadmium Content in Non-Generic Drilling Fluids
Comments on Testimony of Dr. Jerry Neff to EPA
Region X on Proposed BPJ Permits
Trace Metal Content of "Clean" and Contaminated
Barite
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ISSUE PAPER ON REGULATING Cd AND Hg LEVELS IN BARITE/DRILLING FLUIDS
EPA's Effluent Guidelines Division has considered a limit on the
allowable concentrations of cadmium and mercury in either barlte, which is
added to drilling fluids as a weighting agent, or drilling fluid effluents.
Barite is a fine-grained material that is found primarily in two types of
stratification either vein- and cavity-filling deposits or bedded deposits.
The type of stratification is important because bedded deposits tend to be
less contaminated with trace metals than vein- or cavity-filling deposits
(See Appendices F and G).
The approach for the regulation is to promote product substitution of
"cleaner" barite for the more contaminated variety. This objective would
be accomplished by emplacing limitations on the Cd and Hg content of either
the source barite (i.e., allowing discharge of only those drilling fluids
1n which barite with acceptable levels of these metals can be demonstrated)
or the drilling fluid effluent directly.
Because barite represents approximately 60-85 percent of drilling fluid
particulate additives (by weight), and because other additives contain Cd and
Hg levels that are either at or below the proposed limits (Neff, testimony
on EPA/Region IX BPJ permits, 1984; see Appendix F), regulating barite
levels effectively regulates whole mud levels; conversely, regulating whole
mud levels is tantamount to regulating barite levels.
1
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ISSUE: TECHNOLOGIC FEASIBILTY
The limits that are being proposed are zjppm (mg/kg) for Cd and 1 ppm
for Hg. Analyses that have been performed indicate that these limits can
be achieved. The data base is limited: 21 generic muds have been analyzed
(See Appendix D). Although it clearly would be a more sound proposal if
more data were available, the existing data fully support the proposed
limits because all 21 generic muds that were tested would be able to meet
the proposed limits.
The industry's comments have indicated that the mud companies do not
stock "clean" or "dirty" barite. Rather, they batch mix available stocks
to meet API specifications. These specifications address operational
characteristics of barites, primarily specific gravity and soluble salt
contamination, and do not include Cd or Hg limits.
Also, the industry has indicated that although it may be possible to
use only "clean" barite in regions with low levels of drilling activity
(e.g., EPA Regions I, II, III, IV, X, and possibly IX), this feasibility
should not be interpreted as equally appropriate and possible for the
Gulf of Mexico operators. Thus, the matter of scale is an impediment to
the implementation of this approach on a national basis.
However, the analyses of generic muds have not indicated, thus far,
any difficulty in attaining the proposed limits. The industry has not
claimed nor admitted to any effort to "specially" formulate these muds.
Another industry comment is that drilled strata contribute to trace
metal levels. This concern can be addressed by applying these limits to
barite or the mud pits, where such solids largely have been removed.
2
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ISSUE: IMPROVEMENT
Compared to continued usage of vein- or cavity-filling deposits, the
proposed limitations on Cd and Hg could reduce the loadings of Cd and Hg by an
order of magnitude. The discharge of drilling fluids and cuttings is estimated
at approximately two million tons annually (NAS 1983). Of this figure, about
half is comprised of drilling fluids solids. Thus, the proposed limitations
wouJld allow the discharge of up to two tons of Cd and one ton of Hg.
The worst case estimate of Cd levels in drilling fluids is 16 tons
(Neff 1984, Table 1; See Appendix F). Thus, this rule would reduce, for a
maximum, a pollutant load of 14 tons Cd, or an 88 percent reduction. If the
non-generic muds supplied by PESA are used to estimate an average loading
(Appendix D), 3.6 tons could be discharged in the absence of regulation, for
a reduction of 1.6 tons Cd, or a 44 percent reduction.
Data on Hg are not available for domestic nongeneric muds. However,
the Cd levels in Canadian sources is in reasonably close agreement with that
in domestic sources (see Neff 1984, Table 1). These muds have been considered
particularly contaminated, but on the basis of their Cd content, there is no
reason to exclude them from analysis. Using worst-case Hg values for these
muds, 13 tons Hg could be discharged in the absence of regulation. Thus, at
best, a reduction of 12 tons of Hg would result from the proposed limit, or a
92 percent reduction.
Another benefit from promoting the use of "clean" barite is the improve-
ment in the loadings of other toxic metals (See Appendix G). These annual
improvements are estimates based on Canadian data:
arsenic: 65 tons (97%)
cobalt : 3 tons (60%)
copper : 83 tons (91%)
lead : 1369 tons (99.9%)
nickel: 27 tons (82%)
zinc : 2740 tons (99.6%)
3
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ISSUE: ENVIRONMENTAL IMPACT
There are only limited data that address this issue. Laboratory data
(Appendix A) and field data (Appendices B and C) indicate bioaccumulation
levels are low (2- to 10-fold) with the exception of Ba (300-fold) and Cr
(36-fold). Depuration is often rapid (within 24 hours) and quantitative
(40 to 90 percent of excess metals; inversely related to length of exposure).
However, these data have serious shortcomings.
Exposure times in laboratory studies are short (4 to 14 days). Ba uptake
for 8- to 21-day exposures was 8- to 13-fold; exposure for 106 days produced
50- to 300-fold accumulations. Data on Hg uptake are notably absent in labora-
tory studies. Test phases were often inappropriate, i.e., aqueous exposures
for benthic fauna; solid phase tests report no time- or concentration-related
data. Inappropriate tissues often were analyzed. Field studies have only
been conducted on exploratory operations or small bulk discharges; rapid
depuration is not assuring for development operations lasting many years.
In summary, data suggest limited uptake of toxic metals from limited
exposure to drilling fluid. This uptake is especially a concern because it has
occurred following exposure to substances that would be considered not readily
bioavailable based on their physical and/or chemical properties.
Other programs offer limited support. No sediment quality criteria are
presently available. Comparisons to water quality criteria are difficult
because steady-state values are lacking. However, ocean dumping regulations,
indicate that "in the case of solid materials... a limit not more than 50 per-
cent greater than the normal ambient value in the vicinity of the dump site
[should be allowed]" (42FR2467). Industry testimony on BPJ permits states that
Alaskan river inputs, where ambient metal levels are quite high, approximate
1 ppm Cd and 0.1 ppm Hg. Ocean dumping criteria would approximate 1.5 ppm Cd
and 0.15 ppm Hg. The proposed limits of 2 ppm Cd and 1 ppm Hg appear generous,
especially because these discharges are not 1n a designated dump site.
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APPENDIX A.
Summary of Laboratory Studies on Metal
Bioaccvi^ulation Following Exposure
to Drilling Fluids
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Long-tenn Tests: Sublethal Effects
Long-term sublethal effects following exposure to drilling fluids have
been described for metal accumulation, reproduction/teratogenesis, alterations
in growth/development, behavior, physiological/biochemical parameters, and
histopathology. Each of these types of effect are discussed below.
Metal Accumulation
Laboratory data on metal accumulation have been summarized in Table 1-55.
Exposure to drilling fluids or drilling fluid components has resulted in the
accumulation of 6a, Cd, Cr, Pb, Sr, and Zn. One metal for which laboratory
bioaccumulation data are conspicuous by their absence is Hg.
Maximal observed enrichment factors (tissue levels in exposed animals
compared to control animal tissue levels) are generally low (1.6- to 3.4-
fold), with the exception of Ba (300-fold) and Cr (36-fold). Although
functional changes resulting from metal accumulation have not been explicitly
addressed in these studies^ neither overt functional changes nor potential
alterations have been noted.
The ability of exposed animals to clear metals accumulated during exposure
to drilling fluids or components has also been reported. These data are
summarized in Table 1-56. Depuration studies suggest that a substantial
release of Ba, Cr, Pb, and Sr may occur. For whole animal, soft tissue, and
muscle tissue analyses, 40-90% of the excess metal (Ba,Cr, Pb, Sr) that was
accumulated following 4- to 28-day exposures was released during 1- to 14-day
depuration periods. Transient increases were observed in Cr, Pb, and Sr
levels during the depuration period. The only sustained increase (48%) during
this period occurred for Cr in scallop kidney. This finding is somewhat
confounded by a simlar trend (+24%) in control animals.
These data suggest that bioaccumulation of metals as a resuult of drilling
fluids discharges does not appear to be a significant problem. Yet, several
factors argue against this conclusion. Instead, bioaccumulation should be
assessed more properly as a significant unknown.
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First, uptake kineticB are not adequately described. This is largely
attributable to the rather short exposure periods. These exposures were most
often for 14 days or less; occasionally 16-* to 28-day exposures occurred; in
one case, a 106-day exposure occurred but with only one intermediate value
reported.
The available data do not allow for any firm conclusions. Simple
saturation kinetics occur for several metals and species, including Cr in
amphipods, mussels, and oysters; and Cd, Fb, and Zn in amphipods. Zero-order
kinetics with respect to time generally appear at Day 7-14.
However, complex saturation kinetics also occur frequently. For example,
tissue levels of Cr in clam, and both Cr and Ba in scallop kidney, show
apparently zero-order kinetics at Day 2-3, but then inflect with no apparent
plateau through days 14-28 of exposure. The only reported long-term study did
not report adequate data to characterize uptake kinetics. The~~only
observation is that tissue Ba levels appear to be approximately an order of
magnitude higher after 106 days of exposure than after 21 days of exposure.
These data do not support a finding of no significant potential effect.
Since metals are highly persistent, long-term accumulation potential must be
assessed. However, the available data on uptake kinetics are not adequate to
discount metal accumulation as a potentially significant effect of drilling
fluid discharges. It appears that the saturation of one body compartment may
occur within 7-14 days of exposure to relatively high concentrations of
drilling fluids and components. However, additional body compartments for
accumulation also appear to exist because saturation kinetics that are more
complex than first-order kinetics have been reported.
Second, the focus of these studies was often diffuse, and often lacked a
meaningful toxic endpoint for a quantitative hazard assessment.
Bioaccumulation studies first should identify which of two toxicologic
problems is being addressed: (1) human health impacts (edible tissue
analyses) or (2) ecologic impacts (target organ analyses). "Whole body"
levels are probably the least useful data, although they may be marginally
useful for assessment of human health impacts. However, even edible tissue or
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target organ levels can be entirely misleading if a clear differentiation of
impact is inadequately addressed.
Several examples from the existing data are illustrative. Cr and Ba
accumulations in scallop kidney (in contrast to adductor muscle) and Ba
accumulation in grass shrimp hepatopancreas (in contrast to carapace or
abdominal muscle) identify likely target organs. Yet, measurement of
accumulation without any corresponding measurement of adverse functional
changes in these organs only allows for speculation. And whole body tissue
levels, which cannot yield useful target organ data and can only support human
health assessments, have been obtained for several metals in amphipods, a
group of animals not ordinarly consumed directly by humans.
Last, exposure levels were difficult to quantify in a meaningful way for
correlation to field exposure conditions. The assessment of the
bioaccumulation of drilling fluids-related metals will be driven by the
exposure of benthic epifauna and infauna to drilling fluid particulates. Yet,
bioaccumulation studies routinely have tested whole fluids or the aqueous
phase of fluids. These exposures could have_either over-estimated or under-
estimated potential accumulation.
Over-estimation of accumulation could result from the increased
bioavailability of soluble metals present in the aqueous portion of drilling
fluids. However, under-estimation of accumulation is equally likely. First,
although soluble metals are more available than particulate forms, soft-tissue
accumulation following exposure of grass shrimp to insoluble salts (e.g.
barite) has occurred. Second, physiologic chemical reactions may release
soluble metals from particulate forms (e.g., the release of Cr from drilling
fluid solids as a result of acidification). Third, metal concentrations are
routinely 10- to 100-fold higher in the particulate fraction of. drilling fluid
than in the aqueous phase.
Furthermore, in those studies that have tested solid phase material,
accumulation only in response to a deposit layer was measured. Therefore, no
concentration-effect relationship can be constructed that could estimate
uptake from anything but a 100% exposure situation. This design does not lend
itself to a meaningful quantitative hazard assessment.
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V'::l ef' -u Uu£, .Ljc-tJ
Page 1 of 3
Test
Test Substance
(Concentration,
ppm)
Exposure
Period
(days)
Depura-
tion
Metals,
Enrichment
Factor
a
..f b
Organism
Period
(days)
~Ba
Ca
Cd
Cr
Cu
Pb
Sr
Zn
MI •
Onlsimus sp.,
Boekoslmus sp.
XC-polymer-Unlea 1
fluid
20
static
0
i
Whole animal
not gutted
( 50,000)
(100,000)
(200,000)
¦
3.2
6.4
6.0
1.2
1.8
1.4
2.0
2.2
1.5
1.6
1.3
1.5
Palaemonetes
puglo
Whole animal
not gutted
Barlte
5
50
5
50
7,
48-hour
replacement
(t
«t
•f
14
14
150
350
2.2
29
1.3
1.9
1.8
2.2
2
Carapace
Hepatopan-
creas
Abdominal
muscle
Barlte
500
500
500
Barlte
B days
post-ecdysis,
range «8-21
(48-hour
replacement)
106
0
0
7.7
13
12
1.2-2.5
1.9-2.8
1.5-2.8
Carapace
500
60-100
0.07
1.6-7.4
Hepatopan-
creas
500
70-300
1
0.03
Abdominal
muscle
500
50-120
1
0.71
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Table 1-55. Summary of Metal Accumulation Study Results (Cont.)
Page 2 of 5
Test
Organism
Test Substance
(Concentration,
ppm)
Exposure
Period
(days)
Depura-
tion
Period
(days)
Metals,
Enrichment Factor
a
Ref.b
Da
Ca
Cd
Cr
Cu
Pb
Sr
Zn
Mytilus edulis
12.7 lb/gal
7
—
6.6
3
(soft tissue)
lignosulfonate
fluid, MAF
(Cr » 1.4 ppm)
ferrochrome
lignosulfonate
13
(Cr =0.7 ppm)
(Cr »6.0 ppm)
64
Cr CI 3
(Cr =0.6 ppm)
50
Rangea cuneata
12.7 lb/gal
4.
—
1.4
1.7
4
(soft tissue)
lignosulfonate
static
fluid, MAF
(50,000)
h
1.1
1.2
13.4 lb/gal
lignosulfonate
fluid
16,
(100,000 MAF)
static
2.5
1
1.7
—
14
1.6
(layered solid
4,
4.3
phase)
dnity
replacement
1
2.0
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Page 3 of 3
Teat
Organ 1 stb
Teat Substance
(Concentration,
ppm)
Exposure
Period
(daya)
Depura-
tion
Period
(days)
Metals,
Enrichment Factor*
Kef.b
"Ba
Ca
Cd
Cr
Cu
Pb
Sr
In
Crassostrea
9.2 lb/gal
10,
0
2.1
1.1
Rigas
spud fluid
static
(soft tissue)
(40,000 MAF)
4,
0
2.5
24,hour
(10,000 SPP)
replacement
(20,000 SPP)
ft
0
3.0
(40,000 SPP)
••
0
3.0
(60,000 SPP)
«»
0
5.5
(80,000 SPP)
91
0
7.4
12.7 lb/gal
lignosulfonate
fluid
(60,000 MAF)
10,
0
2.3
1.4
static
(20,000 MAF)
14
0
2.9
(40,000 MAF)
14
0
3.9
(10,000 SSP)
4.
0
2.2
24-hour
replacement
(20,000 SPP)
»»
0
4.4
(40,000 SPP)
tl
0
8.6
(60,000 SPP)
»•
0
24
(BO,000 SPP)
ft
0
36
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.1 ii! j I :):]!'.! J ¦ J
table ^-i5» Summary of Meta* Accumulation Study Results (Cont.)
Page A of 5
Test
Test Substance
(Concentration,
ppm)
Exposure
Period
(days)
Depura-
tion
Metals,
Enrichment
Factor
a
¦af b
Organism
Period
(days)
Ua
Ca
Cd
Cr
Cu
Pb
Sr
Zn
ICC I #
Crassostrea
glgas
(soft tissue)
(Cont.)
17.4 lb/gal
llgnosulfonate
fluid
(40,000 MAF)
(20,000 MAF)
(40,000 MAF)
10,
static
14
14
0
0
0
2.1
2.2
0.56
1.0
Placopecten
magellanicus
Uncirculated
llgnosulfonate
fluid
5
Kidney
(1,000)
28
0
8.8
2.6
Adductor
muscle
(1,000)
Low density
llgnosulfonate
fluid
28
0
10
1.2
Kidney
Adductor
muscle
(1,000)
(1,000)
FCLS
(30)
(100)
(1,000)
14
27
14
27
14
14
14
15
15
14
14
14
1.6
2.1
2.3
2
2
2
5.7
3.2
6.0
5.2
7.2
6.0
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Table 1-55. Summary of Metal Accumulation Study Results (Cent.)
Paga > of 3
Test
Test Substance
(Concentration,
ppm)
Exposure
Period
(days)
Depura-
tion
Metals,
Enrichment
Factor
a
Ref.b
Organlsn
Period
(days)
Da
Ca
Cd
Cr
Cu
Pb
Sr
Zn
Myoxocephalus
quadricornis
(gutted)
XC-polymer fluid
(5,000)
(10,000)
36,
48-hour
replacement
3.3
2.9
1.1
3.1
1.25
1.7
1.2
1.2
6
Notes: a* Enrichment Factor - Concentration in exposed group/concentration in controls*
b. References: 1. Tornberg et al. (1980).
2. Brannon and Rao (1979).
3. Page et al. (1980).
4. McCulloch et al. (1980).
5. Lisa et al. (1980).
6. Sohio Alaska Petroleum Company (1981).
c. Abbreviations: MAF - mud aqueous fraction
SPP - suspended particulate phase
PCLS - ferrochrome lignosulfonate
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Table 1*56. Depuration of Metals Accumulated During
Exposure to Drilling Fluids or Components®
Test
Species
Test
Substance
Exposure
Period
(days)
Metal Tissue
Depuration
Level5
Palaemonetes
pugio
BaSOi
Ba
Rangia cuneata
Placopectan
magellanicus
SLF0
(LSP)
MDLF
(MAF)
SLF
(MAF)
LDLF
(WM)
1-4
4
IV
16
II
27
FCLS
14
Sr
Cr
Cr
Pb
Cr
•I
Cr
Cr
Cr
whole
animal,
not
gutted
-90%
soft
tissue
kidney
adductor
muscle
kidney
-90%
-(40-65%)
-75%
-70%
-53%
-60%
+48%d
-63%
-(17-54%)
7
1
4
4
1
3-14
14
14
14
a. Adapted from Brannon and Rao (1979); McCulloch et al. (I960),
Liss et al. (1980).
b. Percentage of excess metal released.
c. Abbreviations: SLF, MDLF, LDLF (seawater, medium density, and low
density lignosulfonate fluids), FCLS (ferrochrome lignosulfonate),
MAF, WM (mud aqueous fraction, whole fluid).
d. Control animals exhibited a 24% increase during the depuration period.
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APPENDIX B.
Summary of Field Studies Describing
Sediment Metal Distributions Resulting
from Discharges of Drilling Fluids and Cuttings
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Trace Metal and Physical Benthic Alterations
An environmental study was conducted in approximately 33 in of water on the
South Texas Outer Continental Shelf (Block 755, Mustang Island Lease Area).
Drilling began December 3, 1976 and was completed on January 15f 1977.
Sampling for suspended material occurred before (September 25-27, 1976),
during (January 7-14, 1977), and after (February 28-March 1, 1977) drilling
operations. Suspended sediment samples were taken in 30 liter Nisken bottles
at five depths at the drillsite. During drilling operations, suspended
sediments in the water column were sampled both within and opposite the plume.
Benthic sediment samples were taken before and after the drilling
operations. Samples for benthic trace metal analyses were taken at the
drillsite and at 1000 m N, £, S, and W. Suspended sediment trace metals were
determined by AAS following acid digestion. Samples were leached with
concentrated nitric acid at 105°C, except for Ba, which was dissolved with a
1:1 concentrated nitric acid and 30% peroxide. Procedural blanks for Zn were
sufficiently, high to render the sainpling data invalid, and therefore were not
reported.
The trace metal content of suspended sediments (Table 1-26) was not
thought to have been effected from drilling activities, although Cr, Cu, and
V show isolated, substantial elevations during and after drilling. Seasonal
variations and the effect of ship traffic from the nearby Port Aransas
shipping lane further confound the interpretation of these results.
Clay mineral analysis showed that montmorillonite was present only in
post-drilling samples and in lower level samples taken during the drilling
operation. This finding suggests that montmorillonite was enriched as a
result of drilling fluids discharges.
Cr, Cu, Hn, and Ni levels apparently did not change in the sediment as a
result of drilling activity (Table 1-27). Fe and V appeared to be somewhat
lower. Xb had a 2.7-fold increase at the drillsite and a 1.9-fold increase at
1000-in stations. It was thought that this increase may have resulted from
drilling activity, possibly from the use of fossil fuel at either the rig or
supply vessels. The data were considered inconclusive as to the direct cause.
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Given (1) the apparently distance-related effect and (2) the contamination of
drilling fluids and cuttings with pipe dope-derived Fb, these effluents appear
to be a contributing source, if not the only source, of the elevations in Fb
levels.
Zn and Cd were the only trace metals that were directly related to
drilling activity. These elements had both a marked increase in
concentrations at the drillsite. Zn was elevated 2.5- to 3.5-fold and Od was
elevated 3- to 9-fold. These metals showed low levels, similar to those taken
before drilling, in the sediment 300 m from the drillsite.
Comparisons of textural variability between the composite pre-drilling and
post-drilling sample suites enable 1-28) showed significant differences (95%
confidence level) for the following textural parameters: skewness, silt
percentge, clay percentage, silt/clay ratio, and mean diameter. The post-
drilling suite was significantly coarser-grained, had a higher silt/clay
ratio, and was less coarsely skewed than the pre-drilling suite. No valid
conclusions *-were- thought' possible"regarding--the -causes of the textural
differences because:
(1) the pattern and number of post-drilling sample sites were
substantially modified from the pre-drilling suite;
(2) substantial seasonal natural variability normally occurs in the area
of this study;
(3) the post-drilling sample site had been relocated approximately 25 m
from the pre-drilling sample site.
The changes, however, are generally consistent with changes observed elsewhere
in sediment texture as a result of drilling operations.
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A rig monitoring survey was conducted at an exploratory site located near
the N lease line of Mustang Island (Texas), Block 792, in 36 in of water
(Department of Interior 1976b). For standard sediment parameters and clay
mineralogy, two samples were collected by a diver, who filled 10 cm x 0.5 m
PVC cores with sediment by scraping them horizontally along the bottom.
Samples for trace meted analysis were collected in acid-cleaned 2 cm plastic
tubes likewise scraped horizontally along the bottom.
Cu, Fe, Pt>, and Ni were determined by atomic absorption spectrophotometry
after digestion of sediment using HF, HCIO4, and HN03. Cd and Cr
concentrations were determined by flameless atomic absorption techniques. V
was determined by instrumental neutron activation analyses. Ba data have been
previously discussed (see Section 1.4.2).
Significant changes in the levels of sand, clay, silt, and CaODj occurred
for before- versus during-drilling phases (Table 1-29). Sand, clay, and CaOOj
levels increased significantly, while silt levels showed a significant
..decrease. ^Comparison ,of~.tbe..during*^ and after-drilling levels stowed that-the-
clay and CaCOj levels decreased significantly and silt levels increased
significantly. The after-drilling levels of sand were not significantly
different from the during-drilling levels. In the during-drilling phase,
drill cuttings were noted specifically at only four 100 m periphery stations
and one 500 m station. Drill cuttings still were observed at these same five
stations in the post-drilling survey, but were notably less abundant.
The averaged trace metal concentrations in the sediments for each station
during the three sampling operations are shown in Table 1-30. These authors
attributed the observed variations in their samples to errors in analysis
combined with minor mineralogicaly and textural differences between samples.
To further support these observations, these authors examined the
metal/iron ratio for Cr, Cu, Pb, Ni, and V (Cd was excluded due to its
extremely low level and resulting higher degree of uncertainty). The data
also indicated that no spatial trends existed in the metal concentrations.
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An environmental study of the Buccaneer Gas and Oilfield in the central
Gulf of Mexico has examined chronic# low-level, heavy metal contamination from
active petroleum production platforms on the OCS (Tillery and Thomas 1980).
Twenty platform structures and four reference sites (i.e., no structures) were
selected. Surficial sediments (the upper 5 cm) were collected at 100 m, 500
m, and 2000 m from four "primary" platform structures along two transects and
along the N axis of one transect for the 16 remaining "secondary" platforms.
All metal analysis/ except Ba and V, were conducted on 5N HNO3 leachates
using atomic absorption spectrophotometry. Ba and V were determined by
neutron activation analysis (NAA). Results from sediment chemistry data
showed concentration gradients that decreased with distance from the platforms
for Ba, Cd, Cr, Cu, Ni, Pb, V, and Zn at one or more platforms. These
gradients were not explained by the variability in sediment characteristics.
Table 1->31 is a summary of trends in the normalized trace metal data for those
platforms that showed metal (s) that could be related to the platform
structure.
Table 1-31 also'shbwed that" more crace metals can be related to platforms
7, 11, and 17 than to 1 and 6. The explanation for this effect was that
sediment load carried into the Gulf of Mexico from the Mississippi River
"masks" the sediment trace metal concentrations that are related to nearby
platforms 1 and € compared to platforms 1, 11, 17, and 19, which are
progressively further from the outfall of the Mississippi River.
Possible sources of these trace metals also were discussed. In addition
to drilling fluids, sources could have been sacrificial anodes on platform
structures, produced brine discharges, pipelines, discarded metal debris on
the bottom, or other activities on platform structures.
-------
Mariani et al. (1980) studied chemical and physical changes in sediments
resulting from drilling fluid6 and cuttings discharges from an exploratory
veil located in NJ 18-3 Block 684, approximately 97 statute miles (156 km)
from the. coast of New Jersey, in 120 m of water.
The (xrMKR arrived at the well site on January 4, 1979, and moved
of location on July 15, 1979. A total of 2160 metric tons of solids were
discharged, ttie first pre-drilling survey consisted of two separate cruises:
August 7, 1978 and August 17-22, 1978. The second post-drilling survey was
conducted approximately 2 weeks after drilling operations were terminated.
The pre-drilling survey encompassed a 2-mile diameter area around the well
site and consisted of 40 sampling stations. The .post-drilling survey
encompassed a 4-mile diameter area and consisted of 48 sampling stations.
Sediment samples were subject to a weak acid leach (25% V/V acetic acid) for 2
hours. This procedure was used to provide an approximation of the metal
content that was thought to be bioavailable.
Results from sediment granulometry analyses on post-drilling samples
stowed that sediments within the study area were very poorly sorted, similar
to pre-drill data, and had a fine-skewed distribution. However, a slight
shift in the graphic mean towards finer sediments (from 2.50 phi to 2.75 phi)
occurred between pre- and post-drilling cruises. Grain size analyses showed
that only the clay-size fraction of the sediments changed significantly
between surveys (Table 1-32), resulting in increased percentages of clays
within the immediate vicinity of the well site, extending to a distance of
approximately 800 m.
Significant differences in the clay mineralogy of the study area occurred
between surveys (Table 1-33). lllite increased from 25.03% to 28.7% and
chlorite increased from 23.7% to 27.5%. Montmorillonite decreased from 20.0%
to 13.8%. Kaolinite increased from 17.9% to 21.3%. Calcite and halite
decreased from 8.43% (calcite) and 50.8% (halite) to 4.4% each.
It was concluded that the increased clay content and changes in clay
mineralogy were not caused by drilling activities alone, since increases in
kaolinite and decreases in montmorillonite are not indicative of clay minerals
-------
present in drilling fluids—montmorillonite (13-40%), illite (0-13%), and
kaolinite (0-5%) (Ayers et al. 19B0b). However, illite, chlorite, and
kaolinite are characteristic of subsurface glacial deposits of the Pleistocene
Period, which could have been released during spudding operations.
Changes in sediment trace metal concentrations (weak acid leachable)
occurred for some elements between surveys (Table 1-34). Increases occurred
in the concentrations of Ba, Pb, Ni, V, and Zn. Arsenic did not change
significantly. Concentrations of Cd, Cr, and Cu decreased between surveys.
Mercury below the detection limit of 0.05 g/g at all stations.
Despite the increased concentrations of Pb and Zn, concentrations were
less than or within the range of values reported by Harris et al. (1977, 1979)
for sampling stations approximately 11 km from the study area. Changes in
concentrations of Pb and Zn were thought to reflect the natural variability of
the study area.
Concentrations of V' exceeded the seasonal ranges of concentrations
reported by Harris et al. (1977, 1979). However, the lack of a recognizable
spatial distribution for V suggested that some other factor affected this
area. Increased Ba concentrations were detected at six stations and
apparently were contained within a 2-ciile radius of the rig. Increases in Ni
were noted at ten stations and were confined within a 1-mile radius of the
rig. Based on the reported concentrations of nickel (13.5 to 18.1 ug/g) and
vanadium (22.7 to 29.7 ug/g) in drilled discharge solids (Ayers et al.
1980b), however, it was thought unlikely that drilling discharges were solely
responsible for these increases.
Following the publication of these data, several re-evaluations of the
analytical procedures occurred. To facilitate meaningful comparisons between
this study and other sediment trace metal data, archived samples were analyzed
for Ba and Cr using neutron activation analyses. During this re-evaluation
errors in standard curves also were discovered. These revised data have been
included in a final report scheduled for release by early 1983.
-------
A study has investigated the environmental distribution of metals from
drilling fluids discharged into the Beaufort Sea, near the Mackenzie River
Delta (Crippen et al. 1980). A post-operational artificial island drilling
site, Netserk F-40, was constructed with material consisting primarily of
medium sand to fine gravel (0.4 mm to 20 mm grain size). The well was spudded
on November 8, 1975 and was completed on May 19, 1976. Approximately 7,300
barrels of waste drilling fluid were discharged. Netserk was in an advanced
state of erosion at the time of the post-operational survey in the summer of
1977.
Sediment samples were taken using a gravity-type corer wherever possible,
or a Ponar grab at stations where the corer could not pentrate the substrate.
A portion of the upper 2-5 cm of sediment was frozen for chemical analysis.
The samples were analyzed for mercury (Hg), arsenic (As), cadmium (Cd),
chromium (Cr), lead (Pb), and zinc (Zn).
Netserk drilling fluids and cuttings were analyzed approximately every 300
m of drilling. An estimate of the quantity of each metal discharged during
drilling was calculated based on the estimated amount of each major drilling
.fluid. .constituent -discharged„and .its^approximate. mstal .composition. An
evaluation of the metals most likely to be significantly higher than
background indicated that Hg was expected to be the best tracer of drilling
fluids in these sediments.
Sand and gravel were observed in the upper few centimeters of sediment to
at least 300 m offshore. This coarser material probably originated from the
construction and erosion of Netserk and suggested that the predominant
directions of subsurface water was NE-SW.
Hg contamination of sediments was obvious within 100 m of the point of
discharge (Figure 1-5) and Hg levels were somewhat elevated above mean
background levels (0.07 ug/g) at several other stations (Table 1-35). The
highest mean value recorded was 6.4 ug/g and was located about 45 m from
shore, just N of the discharge.
The concentrations of As, Cd, Cr, Pb, and Zn in surface sediments exceeded
background levels at one or more stations in the vicinity of the discharge
-------
(Figures 1-6 to 1-10, respectively). Subsurface concentrations of most
metals, excluding Cr, were substantially higher than surface sediment samples
45 m SW of this discharge location. This sample was thought to be a pocket of
drilling fluid from operations prior to the use of chrome licposulfonate.
This observation suggested that dynamic sedimentation in this area was
well under way prior to the completion of drilling operations, because chrome
lignosulfonate was a major additive of the drilling fluid during the last 600
m of drilling. Erosion of the Netserk gravel island was thought to have had
an advantage in that discharged drilling fluid components had been diluted
and/or buried, thus reducing exposure to these contaminants.
-------
These sediment metal studies (including an above-ice discharge study,
described in detail in Section 1.1.5.1), when considered as a group (Table 1-
A), suggest the enrichment of certain metals in surficial sediments may occur
as a result of drilling activities. While confounding factors occur in most
of these studies (i.e., seasonal variability and other natural and
anthropogenic sources of these metals) a distance-dependent decrease in metal
levels frequently is observed. However, although drilling activities are
implicated as a source of metal enrichment, discharged drilling fluids and
cuttings probably are not the only drilling-related source.
The only two metals that appear to be elevated around rigs or platforms
and are clearly associated with drilling fluids are Ba and Cr. A study in the
Canadian Arctic found that Bg would be the best trace metal tracer of
discharged fluids. OTie examination of Hg levels in fluids and sediments for
domestic operations is notably under-represented in the studies that have been
reviewed. The degree of similarity between Canadian and domestic operations
has not been evaluated. However, the findings of the Netserk study and lack
of information on domestic operations indicate that the relationship between
drilling fluid- discharges -and sediment "Hg levels' should be 'further
clarified.
Metals that appear to be elevated as a result of drilling activities and
not solely related to drilling fluids include Cd, Hg, Ni, Pb, V, and Zn. Cd,
Pb, and Zn may be associated with drilling fluids as contaminants that occur
from the use of pipe dope or pipe thread compounds. Hg, Ni, and Zn may
originate from sacrificial anodes. Cd, Pb, and V may also originate from the
release of fossil fuel in drilling operations. This release can result from
burning, incidental discharges or spills from the rig or supply boat traffic,
or use as a lubricant in drilling fluids. In the Gulf of Mexico platform
study, brine (formation water) discharges were identified as an additional
potential source of metal contamination.
Although these metals were enriched in the sediment, enrichment factors
were generally low to moderate, seldom exceeding a factor of 10. The spatial
extent of this enrichment also was limited. Either of two cases occurred:
enrichment was generally distributed but undetectable beyond 300-500 m or
-------
enrichment was directionally-biased by bottom current flows and extended
further (to about 1800 m> but within a smaller angular component.
These considerations suggest that exploratory activities will not result
in environmentally significant levels of trace metal contamination. However,
other factors, such as normal sediment loading or proximity either to
commercial shell fisheries or to subsistence populations, could alter this
conclusion. Sediment trace metal levels resulting from development drilling
operations needs further clarification, especially relating to the dynamics
and extent of sediment contamination.
-------
Above- and Below-Ice Dispersion
Above-Ice Discharges
A study was conducted to monitor the environmental fate associated with
above-ice disposal of drilling fluids and cuttings in the Beaufort Sea (Schio
Alaska Petroleum Company 1982). Three well sites were chosen (Figure 1-11):
Sagavanirktok Delta wells #7 and #8 (Sag 7 and Sag 8) and Challenge Island
well #1 (Challenge 1).
Approximately 3,000 bbl of drilling fluids and cuttings obtained from the
Challenge 1 operation were discharged as evenly as possible at Sag 7 during
mid-April 1981. Water depths at this site ranged from 2.9-3.5 m. At Sag 8, a
snow berm 0.5-1.5 m high was constructed to test its impact on river
overflooding. Water depths varied from 1.3-1.7 m. Ice thickness ranged from
0.9-1.5 m and was grounded at five of eight sampling stations. Approximately
2160 bbl of drilling fluid effluents were discharged at this site from March
16-30, 1981.
Challenge 1 consisted of three disposal sites. Two disposal sites (A and
B) were located in water depths ranging from 2.4-2.9 m, while at Site C, water
depths ranged from 2.7-5.0 m. Approximately 5,000 bbl of frozen fluids and
cuttings were discharged at Challenge 1 from March 14-25, 1981. At Site A,
approximately 1010 bbl of effluent was spread in a 2-3 cm thick layer over
most of the site. An additional 250 bbl of effluent was mixed with snow and
piled in a corner of Site A. Approximately 2,860 bbl of frozen drilling
effluent was spread in a 10-20 cm thick layer over disposal Site B. At Site
C, approximately 890 bbl of frozen drilling effluent was placed in piles,
nominally 75-90 cm high.
-------
Trace metal analyses were conducted on samples of drilling fluid from both
Challenge 1 and from disposal site samples that were collected in late March,
1981 and variously thereafter. Comparison of pre- and post-discharge bottom
sediment samples from Sag 7 indicated significant decreases in levels of Ba,
Cd, and Bg that were judged unrelated to drilling fluids. Analyses of pre-
and post-discharge bottom samples from Sag 8 indicated that only Ba levels
significantly decreased.
Results from pre- and post-discharge analyses of Challenge 1 sediment
samples indicated significant increases in levels of Cd/ Cr, Pb, and Zn at
Sites A and B, and in levels of Cu, Pb, and Zn at Site C. Increases of Cr and
Zn were considered related to drilling fluids disposal. Cd data were not
considered to be explained by effluent discharges because Cd levels in the
effluents and predischarge sediments were similar. Elevations in Pb were not
judged to be drilling fluid-related because of spatial patterns, other
sediment characterisitcs, and because Site C did not melt in place.
However, elevations of Cd and Pb levels could be effluent-related in view
of the following data. Although Cd levels in early drilling fluid samples
(0.2 rog/kg) were similar to pre-discharge sediment levels (0.19-0.35 mg/kgT7
an enrichment of Cd in drilling fluid effluents occurred at all disposal sites
over time, to 0.8-1.1 mgAg. And for Cd, Cr, Pb, and Zn, sediment levels were
inversely related to distance from disposal sites (A and B) for 0-60 m, 60-
85 m, and 250 m data sets (Table 1-36).
Also, for Cd, Pb, and Zn at Sag 7 and Cr, Cu, Pb, and Zn at Sag 8 a
consistent spatial pattern of enrichment at the near-field stations
(approximately 85-200 m) occurred relative to pre-discharge levels and either
within-site or far-field (315-585 m) stations. These enrichments were not
statistically significant. However, trace metal levels had 95% confidence
levels 30-130% of the mean, averaging about 65%. This large variability
reduces the ability to statistically resolve differences among data sets.
Nonetheless, near-field enrichments were consistent. For both Pb and Zn,
enrichment was 1.3-fold at Sag 7 and 1.2-fold at Sag 8, versus 2.3*- to 2.6-
fold for Pb and 1.4-fold for Zn at Challenge 1. Cr levels at Sag 7 increased
2-fold versus 1.4-fold at Challenge 1.
-------
These data suggest that drilling fluid disposal nay have increased
sediment levels of Cdr Cr, Pb, and Zn. However, these increases generally
were small (1.2- to 4-fold) and localized (within approximately 200 m). An
unresolved paradox is why better spatial trends were observed for Challenge 1
(Sites A and B), which did not melt in place than for Sag 7 and Sag 8, which
did melt in place.
A study has assessed the impacts of above-ice drilling effluent disposal
techniques in the Beaufort Sea (Sohio Alaska Petroleum Company 1981), between
the Midway Islands and Prudhoe Bay (Figure 1-15). The Reindeer Island
Stratigraphic Test (RIST) well was drilled during January through April, 1979.
Water depths and sea ice thictaess were measured in April, 1979.
Field tests were conducted to describe the fate of drilling effluents
discharged above the sea ice. Effluents were discharged at three locations
(Figure 1-16). An offshore site (Test Plot 6) was located in approximately
6*4 m of water. A nearshore-s-ite (Test Plot 7) was located on grounded sea
ice, in an area overflooded by the Sagavanirktok river. A multi-source, below-
ice discharge of drilling effluents was conducted to simulate a worst case from
above-ice disposal. This offshore test site (Test Plot 4) was located in
approximately 6.7 m of water.
Bermed snow subdivided Test Plot 6 into nine pits, each of which received
approximately 120 bbl of effluent. At Test Plot 7 dispersion resulting from
overflooding was maximized by pumping effluent directly on the ice surface and
allowing it to free-flow, without berms.
Observations at Test Plot 6 indicated that most drilling effluent solids
remained in place until later stages of breakup. Reconnaissance on June 1,
1979 indicated the offshore site was generally intact. On two occasions (June
8 and 11, 1979) partial effluent drainage, presumably through the ice, was
noted for the liquid phase. On June 14, 1979 the ambient ice sheet showed 0.7
m of surface melt. Within the disposal site, an additional 0.3-0.7 m melt
occurred. By July 12-14, 1979 the ice sheet had completely broken up. The
site was not located, although a 0.2 km section of the ice road adjacent to
the disposal site was located about 28 km E of its original position.
-------
Samples of drilling fluids were obtained from Test Plot € on July 1, 1979
and natural sediments were obtained from the surface of sea ice during the
later stage of breakup. Analyses of trace metal levels indicated that the
remaining drilling effluents were similar to natural sediments for most trace
metals analyzed. The exceptions were elevated levels of Ba (47,500 ppm versus
approximately 1000 ppm) and Fe <72,500 pptn versus 36,000-40,000 ppm).
Reconnaissance of Test Plot 7 indicated that overflooding with at least
0.2-0.3 m of river water occurred between Hay 9-12, 1979. Qualitative
observations indicated that this overflooding dispersed much of the effluents.
By June 14, 1979 a major flood channel had removed ice and effluent from
approximately half of the site. Coastal fog precluded observations during
late June, 1979. All ice had moved out of the disposal site area by July 12,
1979.
Satellite beacons at Test Plot 7 ceased to transmit on June 19 and 30,
1979. Although these beacons were not located, they had not moved more than
2 km (the limit of accuracy) prior to signal loss. The base for one beacon
was later located 0.5 km S of the disposal site.
A simulated, above-ice disposal test was conducted on May 6, 1979 at Test
Plot 4. Twenty-five holes were augered on 6.1 m (20-foot) spacings at the
center of the test plot. During the test, 40 bbl of drilling fluids were
discharged through each hole to simulate a worst-case release of drilling
effluents falling to the seafloor directly below the above-ice disposal site.
Grain size analyses of settling pan sediment indicated that a rapid
decrease in deposition rates occurred for most particle sizes. At the center
of the discharge hole, deposition was 729 mg/cm2 for all grain size fractions.
At 1.5 m and 3.0 m, average deposition was 313 mg/cm2 and 168 mg/cm2,
respectively. It was estimated that the average deposition of all particle
sizes was about 200 mg/cm2 over the test site. The average deposition rate
for particles less than 45 microns, measured 3 m from the discharge point, was
in the same general range of deposition rates measured at two below-ice
disposal site (166 mg/cm2 versus 66-368 mg/cm2, respectively; see Section
1.1.5.2). Bottom sediment trace metal levels indicated the presence of
drilling effluents 3 days after the discharge, but not 3 months post-discharge.
-------
Modeling of above-ice disposal site dynamics was considered too difficult
to perforin because of the complexity of the breakup process. Deposition of
solids was thought to be gradual and primarily controlled by currents, wave*
induced turbulence, and flocculation of the clay-sized fraction of the
effluent. Most solids (with the exception of cuttings) probably would be
resuspended several times or remain in suspension throughout the summer.
Dilution of the effluent liquid fraction was thought probable during the
breakup process, primarily as a function of local melting and drainage
patterns of the parent ice sheet.
-------
1. I.: Below-Ice Dischargee
A study has assessed the impacts of below-ice drilling effluent disposal in
the Beaufort Sea (Sohio Alaska Petroleum Company 1981), between the Midway
Islands and Prudhoe Bay (Figure 1-15). Water depths and sea ice thickness
were measured in April, 1979. Field and laboratory tests were conducted at
Test Plots 1 and 2 (Figure 1-17) to assess physical effects of below-ice of
effluent disposal and to provide data for modeling efforts.
Field discharges were monitored through a series of 48 cm diameter auger
holes along predetermined transects at varying distances from the discharge
point. Approximately 3-4 liters of Rhodamine WT dye were pumped into an
effluent transporting truck. The mixture was agitated for several hours to
insure complete mixing and stabilization of the dye and drilling effluents.
Discharge conditions and physical characteristics of the drilling effluents
are summarized in Table 1-37.
Settling pans were recovered approximately 24 hours after the completion
ofLthe .test-discharge , and -wet sieved^- Results-of -the analyses for Test Plots
1 and 2 are summarized in Tables 1-42 and 1-43. The deep-water test
resulted in a broader deposition pattern than the shallow-water test.
Deposition at Test Plot 1 peaked at 6.1 m (158 mg/cm2) and decreased to 38
mg/cm2 at 24.4 m and 62 mg/cm2 at 30.5 m. At Test Plot 2, deposition was
maximal at 3.0 m (77 and 440 mg/cm2) and decreased to 0.7 and 0.4 mg/cm2 at
30.5 m.
Trace metal analyses of drilling fluid samples and of bottom sediments
were conducted both within and near the disposal sites. At Test Plot 1 there
were no notable differences as a result of drilling activities. At Test Plot
2, however# three metals showed possible enrichment: Co, Cu, and Fe.
Compared to sediments levels obtained on 4/8/79, CO was enriched 1.9-fold (20
ppm to 38 ppm) 1-4 months later. Cu was enriched 1.7-fold after 1 month (44
ppm versus 26 ppm) but only 1.5-fold after 4 months (38 ppm versus 26 ppm).
Fe was enriched 1.25-fold after 1 month, (2.98% versus 2.38%) but not after 4
months.
-------
Table 1-26. Trace Metals (ppm) In Suspended Sediments*
Cd
Cr
Cu
Fe
Mn
N1
Pb
V
PRE-DRILLING
SURF
8.4
305
69.5
12700
128
TR
82.8
TR
8m
380.0
174
56.0
47000
116
TR
128.0
TR
16m
405.2
188
82.8
10900
1293
TR
258.6
TR
24m
744.1
255
94.0
12500
1185
TR
86.2
TR
32m
305.7
32
18.9
21300
2779
27
30.2
24
DURING
DRILLING
SURF
9.9
173
76.1
22700
128
TR
173.1
TR
In
8m
61.9
69
42.1
19500
605
26
522.6
41
Sed.
16m
15.8
189
68.6
16200
366
TR
58.2
TR
Plume
24m
1.8
470
642.1
16800
71
761
15.2
TR
32m
411.0
106
27.0
15300
55
TR
19.6
TR
SURF
511.9
172
61 k.
15600
60
TR
51.2
TR
Opp.
8m
16.7
266
61.8
18000
116
TR
40.0
TR
Sed.
16m
22.5
46
23.3
17400
337
TR
45.0
TR
Plume
24m
3.8
62
27.7
14600
57
TR
35.2
TR
32m
0.7
93
38.2
18600
212
40
62.4
136
POST-DRILLING
SURF
0.8
291
64.1
13000
501
TR
62.9
267
Rm
1.2
263
67.4
15700
444
TR
38.3
139
16m
13.2
2417
TR
17200
139
TR
TR
TR
24m
7.3
1287
93.3
12700
220
TR
46.7
TR
32m
7.0
1011
425.8
21800
387
247
224.1
588
BLK A
0.0
0.0
0.0
0
0
0
0
0
BLK B
0.0
0.0
0.0
0
0
0
0
0
*From Department of the Interior (1976a)
-------
Table 1-27, Trace Metals - Jlenthlc Sediments (PPM)#
Pre-Drllltng
Site
Ba
Of
Cr
Cu
Pe
Mn
Nl
Pb
¥
Zn
Code
DS
110.8
0.07
23.8
5.9
20200
312
14.3
7.6
17.1
64.7
TAK
M-1000
112.2
0.07
25.3
6.5
20500
320
17.7
7.1
17.6
69.4
TCI
1-1000
107.0
0.06
19.6
4.9
18200
2/9
17.0
6.0
17.3
61.0
1KB
s-iooo
95.1
0.08
31.4
6.8
22100
275
16.5
6.3
20.)
71.0
TJB
V-THB
09.0
0.08
40.9
5.4
19000
292
13.6
6.1
15.9
66.1
THE
tqt
94.8
0.07
29.7
6.0
21000
293
15.6
6.4
18.2
69.6
T*)T
TQZ
104.4
0.08
29.1
5.9
21400
252
14.6
7.4
15.9
69.5
TQZ
Post-Dv
tiling
0S-1
470.7
0.61
21.5
6.7
16400
279
12.3
20.5
9.2
168.6
B0SM
-2
512.7
0.49
16.9
5.0
14200
>0
9.0
18.3
8.4
219.6
B0SV
-3
77.8
0.22
21.3
6.3
18700
in
12.7
15.8
11.9
68.6
BOW
If-1000
50.0
0.11
19.5
6.8
19000
3
14.1
12.1
12.4
62.2
BOUQ
E-1000
46.5
0.03
21.9
5.9
17400
10
14.7
11.8
12.3
58.1
BOTH
S-1000
52.6
0.04
20.6
6.7
18300
il
12.6
12.9
13.7
62.7
BDWB
W-1000
59.2
0.04
21.6
6.8
19300
9
14.5
14.5
11.7
63.8
BOIIt.
*From nep.irtmrnt of the Tntprlor (1976a)
-------
Table 1*28. Analysis of Variance for Pre-Drilling
and Post-Drilling Suite Comparisons'1
Hypothesis: Bo: Di * 02
Statistic: F
Risk of Type 1 Error: « 5%
Critical Region: F> (1,36 d.f.); • 4.12
Parameter F-vaiue
Sand % (*2 _ 4.67,x2 ¦ 6.08)+
1.58
Silt « (Xj « 45.47, %2 « 55.09)
14.97*
day % (X} «= 49.82, x2 » 38.82)
22.93*
Sand/Mud ratio (x^ ® 0.049, x2 * 0.068)
1.87
Silt/Clay ratio (xj « 0.931, x2 * 1.556
17.98*
Mean Diameter (x^ = 7.72, x2 * 7.13)
24.25*
-Standard Deviation (x^« 2.04," x2 '« 2.15)
3.80
Skewness (x^ • -0.157, x2 ¦ -0.008
7.41*
Rurtosis (x1 ¦» -0.947, x2 « -0.822
0.70
+ Xj «= pre-drilling mean, x2 « post-drilling mean
* e significant difference
a. From Department of Interior (1976a)
-------
Sable 1-29. Percentage weight of sand, clay, silt and CaCO* in
the bottom sediments of the oil rig study site®
Drilling Phase Sand Clay Silt CaCD^
Before
XU S.D. 1.311.4 45.0*5.0 57.3*13.3 3.5*2.3
Range 0.5-7.9 31.6-51.5 45.0-98.0 0.6-9.3
During _
XI S.D. 6.912.6 53.8+17.6 39.&18.2 12.3+2.4
Range 4.1-17.3 38.0-93.6 1.3-55.7 6.5-17.9
After _
Y± S.D. 9.1±5.3 39.7±5.7 50.6+4.4 6.6+8.2
Range 4.1±26.8 27.0-48.3 36.6-57.9 1.4-43.5
£ Tests ( £ 0.05)
Before vs during -8.964* -2.292 3.971* -12.415*
During vb after -1.750 3.600* -3.031* 3.186
* Significant difference at .£ 0.05
a. Department of Interior (1976b).
-------
Table 1-30. Rig Monitoring Study, Surface Sediment Trace Metal Concentrations8
Bab Cd Cr Cu Fe Ft> Ni V
Before 575195 0.07±0.2 49.5±7.8 14.011.2 3.000±0.3 19.211.6 25.6+2.3 87±15
During 100QH12 0.07±0.03 55.4±5.2 14.2±0.9 2.90±0.3 22.01.2 24.6±2.1 84£L0
After 1096±109 0.07±0.03 52.7±6.4 14.QH.7 2.90±0.3 21.912.0 29.1±4.3 85£L8
a. Prom Department of Interior (1976b)
b. All metals as ppnr except Fe (%)
-------
Table 1-31. Suronary of trace metal concentration In surflclal sediments normalized to the
hydrous Iron fraction (I), the X clay content (C) and the total hydrocarbon content (HC)t
Petroleum
Ba
Cd
Cr
Cu
Fe
N1
Pb
Zn
V
Metals Associated
Platform
I C MC
I C HC
I C HC
1 C HC
C HC
I C HC
I C HC
I C HC
1
c
HC
with Platforms
1
~ ~ ~
0 0 0
~ 0 ~
0 0 4
0 ~
0 + +
4 4 4
0 0*
0
0
0
Ba, Pb
6
0 0 0
0 0 0
~ ~ 0
0 0 0
0 0
~ ~ 0
0 0 0
~ 0 0
0
0
-
Cr, H1, Zn
7
~ ~ ~
0 0 0
4 4 4
4 4 4
0 0
0 0 +
4 4 4
4 4 4
0
0
0
Ba, Cr, Cu, Pb, Zn
11
4 4 4
4 4 4
~ 0 ~
4 4 4
0 0
0 0 0
4 4 4
4 4 4
0
0
0
Ba, Cd, Cr, Cu, Pb,
17
4 4 4
4 4 4
0+0
4 4 4
0 0
0*0
4 4 4
4 4 4
0
0
0
Ba, Cd, Cu, Pb, Zn
19
0 0 0
0 0 0
0 0 0
0 0 0
0 0
0 0 0
0 0 0
~ ~ 0
•
0
Zn
~ = normalized data Increases as distance from platform decreases.
- = normalized data decreases as distance from platform decreases.
0 = no change 1n normalized data with distance from platform or no
trend detected In normalized data with distance from platform.
*From Tilt pry .irul Tliomns (19RO).
-------
Table 1-32. Grain Size T-Tests for Groups Means of Pre-Drilling and Post-Drilling Data*
Crtln Sift
•anqe of Concentratloni (Si
1
Olstanct fro* Veil
Site for Pott-Drill.
Imp of Concentrations (f)
for Southern Quadrant
Comparison of Southern
Quadrants Pre- and Post-
Orllllm Data
Pre-Or iIIinq
Posl-Drllltnj
In; Data (Melert)
t-Value
Pre-Or llliflf
Post-Drill <119
t-Valoe
Grant
0.30-9.45
0.05-4.05'
1609
1.57
0.30-9.45
0.70-3.351
1.19
0.30-9.45
0.05-3.35
731
1.90
0.30-9.45
0.05-1.75
365
1.69
Stud
74.1-87.65
71.1-87.70
1609
1.60
74.10-87.65
73.35-87.65
1.77
74.1-87.65
71.1-87.65
711
1.8?
74.1-87.65
71.1-87.65
365
1.37
sin
8.8&-13.55
8.30-16.5
1609
1.45
8.80-13.55
8.85-14.95
1.89
8.80-13.55
8.85-16.5
731
l.«6
a.so-n.ss
8.85-16.5
365
1.57
Clay
4.95-11.35
4.95-17.10
1609
7.74*
6.45-11.35
7.15-11.40
1.35*
¦Significant rta< 0.05.
IPost-Orllllnf values generally lets tkm Pre-Ortlllng values.
*From Marian! et al. (1980).
-------
Table 1-33. Clay Mineralogy t-Tests for Group Means of
City
Mineral
Montmoril-
lonite
Range of Concentrations (X)
Pre-
Drllllng
Post-
Drilling
14.45-26.90 10.2 -18.10c
Distance
from Well
for Post-
Drilling
Data
(Meters)
3218
t-Value
-9.81
llllte
21.75-30.20 25.0 -30.4
3218
R.B6C
Chlorite
21.3 -26.05 21.8 -29.6
3218
«».26*
Kaollnlte 14.50-20.70 18.50-24.0
3218
8.91
Calclte
6.45-10.80 3.0 -10.101
3218
-10.78^
Halite
4.05- 6.05 3.70- 5.80
3218
-4.84
a
From Marlanl et al. (1980).
Post-drilling values generally less than pre-drllling values.
'Significant at a » 0.05.
Pre-Drllllng and Post-Drilling Data*
Range of Concentrations (X)
for Southern Quadrants
Pre-
Drllling
16.80-22.50
22.45-28.30
21.40-26.05
14.75-20.7
6.45-10.95
4.05- 5.80
Post-
Pr 11ling
10.20-17.80b
27.4 -29.6
21.80-28.7
19.0 -24.0
3.1 -10.1b
3.8 - 5.8b
Comparison
of Southern
Quadrants
Pre- and
Post-Drilling
Data t-Value
-8.20*
7.42c
«.10c
6.75c
-7.60c
-2.60C
-------
Table 1-34
Trace Metals In Sediments t-Tests for Gr^up Means of Pre-Drilling and Post-Drilling Data
(From Marian et al., 1980)
Trato Nltall
¦aw of Cmnlntim (m/«}
Btltanct fro* Mil
Slt« for rett-Orlll.
t-faWe
laufi «T CtMWIrallMt (09/1)
for Southern OurtraMt
tt-rfllM of Swltani
rra- and Ntt*
OrllllM Oat a
t-Vala*
rr*-Urllllng
Fotl-Mllin,
Data (Hrlt'rt)
Pra-Dr111ing
Poll-Drill in,
Arinlc
0.79-1.29$
0.69-1.SO
)2I8
0.44
0.790-1.29S
0.69-1.60
O.M
o./9-i.m
0.69-1.M
1609
O.M
0.79-1. ?«
0.69-1.60
7)1 ,
0.17
o.iM.m
0.69-1.60
MS
0.S7
¦art at
d.n-iK
<1.60-41.46
1218
0.7)
1.60-S.)
1.60-41.46
0.72
<1.60-41.46
160*
0.84
<1.60-9.6}
<1.60-13.17
7)1
0.40
<1.60-9.61
<1.60-1).17
M
O.S)
Catal*
0.002-0.112
0.004-0.0))*
3211
-7.69*
0.01S-0.007
0.004-0.0)1'
•7.70*
Cfcroslaa
0.047-0.347
0.007-O.S10>
1218
-3.70*
0.047-0.)09
0.009-0.SI0>
-1.29
0.047-0.347
0.007-0,S10>
1609
-).68*
(apt*r
0.007-0.2IS
0.006-0.0691
)218
•0.76
0.011-0.068
0.008-0.089
O.M
0.007-0.2U
0.006-0.009
1609
•0.70
0.007-0.21s
o.ooa-o.oat
7)1
•0.4)
0.007-0.2IS
0.000-0.009
XI
-0. JO
lead
0.10-1.M
2.10-6.20
)218
13.82*
0.27-1.SS
2.SS-C.20
9.46*
0.16-1.S«
2.10-0.20
1609
D.S2*
¦lekal
<0.20-1.70
0.490-4,. ISO
)2I8
4.22*
0.20-1.70
0.62-4.IS
2.88*
<0.20-1.70
0.490-4.ISO
1609
4.24«
Imflni
O.S4S-I.48-
1.14-14.16
1218
6.60*
0.64-1.48
1.14-14.16
4.20*
0.S4S-1.48
1.14.14.16
1609
6.62*
Hue
0.7IS-3.01S
0.28-12.20
)2I0
2.89*
0.7)5-2.410
0.6S-12.28
2.67*
0.7IS-3.01S
0.48-12.20
1609
2.92*
•
•SlflftlflcMt at a • O.M.
'fOtt-OHIIIng film fHHrillf l«i than Pr>-Drilling valect.
-------
Table 1-35. T-test results for • comparison of netal levels
in sedlnents at four Netserk F»40 transects
(greater than 90 a offshore)f
Mean Hg Level of significance
Transect
(vg g""1)
a
O
150"
225"
335"
- 60c
0.0V6
_
>99.9
99
>99.9
150*
0.041
>99.9
-
NO
NO
225°
0.073
99
NO*
-
NO
335°
0.069
>99.9
NO
NO
* less than 99 percent
aFrom Crippen et al. (1980).
-------
Itable I-A. Staimry of Sediment Trace fetal Alterations (ran Drilling Activities*
Trace Metal
ta
Gd
Cr
Oi
ng
Ni
R>
Qulf of Knlcn,
Mustang Island area
suspended sediment
surflclal sedinent
Glilf of MnioDf
Hustoiq Island area
N>
M)
l«>
4
13-9*)
4
(8-31i)
4 ND
(7-10*)
ND
ND
1
(6-25*)
(2.5-3.9*1
Central Qilt of Mexico
Ft)
ND
Nid-Atlantlc
BLD
4
(2.5k)
4
(4-4*)
4
(2-9.3*)
4
(«*)
NKkmie River Delta
(1.2-2.5)
4
(2-6*)
4
(4-7*)
ND
4
(1.2-15*)
ND
(1.5-2.2X)
N>
4
(11.7>)
Beaufort Sea
M)
4
(2-6*)
4
(1.4-2*)
ND
(1.2-2.6*)
N)
(1.2-1.4*)
a. Akpted fran Department of Interior (1976a, 1976b, 1977)* Tillery and items (1980)»
Nariani et al. (1980); Crlppen et al. (1980).
b. Abbreviations! ND (not determined)
4 (incitwed Irvrls (magnitude change In parentheses) related to drilling)
(decreased IpvpIr related to drilling)
4 lisohtnl increases, not a clearly diststce-related pattern
fU) (below the levrl o[ Election)
-------
Table 1-36. Sediment Trace Metal Levels at Challenge 1, Sites A and B*
Metal
tag/kg)
Data Set
03
Cr
Fb
Zn
0 - 60 m
1.40
12.4
17.2
49.8
60 - 85 m
1.29
7.07
15.8
47.3
250 in
1.18
7.43
14.3
45.8
Pre-discharge
0.19
5.2
6.1
33
* Adapted from Sohio Alaska Petroleum Company (1962)
-------
feble 1-37. Sumary of Discharge Conditions and Physical Characteristics
of Drilling Effluents Used in Belcw-Ice Test Discharges*
Test Plot 1 Test Plot 2
Test Date
April 30, 1979
April 22, 1979
Volume Discharged
100 bbl
60 bbl
Discharge Rate
1508 bbl/hr
21.6 bbl/hr
Discharge Temperature
23° C
19° C
Density (at 20° C)
1.16 g/ml
1.05 g/ml
Ice Thickness
1.8 in
1.9 in
Water Depth
8.4 in
5.5 m
Adapted..fran Sohio-Alaska Petroleum -Cc.pany (1981)
-------
Table 1-42. Sumtary of Deep Water Belcw-Ice Particulates Deposition
of Discharged Drilling Fluids and Cuttings (Test Plot 1)*
Sediment Pan Deposition (mg/crn*)
Distance
(m)
N
E
S
W
Average
3.0
124.7
137.3
159.3
129.0
137.6
€.1
146.5
175.4
132.7
176.3
157.7
12.2
110.1
100.8
61.5
71.0
85.9
24.4
36.3
-
40.1
-
38.2
30.5
-
92.9
-
31.1
62.0
* Adapted from Sohio Alaska Petroleum Company (1981)
-------
Mble 1-43. Summary of Shallow Water Belov-Ice Particulates Deposition
of Discharged Drilling Fluids and Cuttings (Test Plot 2)*
Sediment Ban Deposition (xng/an^)
Distance
to)
15°T
105°T
Average
3.0
77.0
440.4
258.7
12.2
27.0
49.8
38.9
16.3
29.1
34.2
31.7
30.5
0.7
0.4
0.550
121.9
< 0.2
0.4
< 0.300
243.8
< 0.2
< 0.2
< 0.200
487.7
< 0.2
0.4
< 0.300
* Adapted from Sohio Alaska Petroleum Company (1981)
-------
I ' zone of surficel sand and grave! due to Netserk constructor! and erosion
f777l -09 to016UBS"'
76 to 1ug B"'
¦¦ >6 jjq g"1 Dry we>flW background Hg concentrator! 068 y; B"'
Figure 1-5. Distribution of Mercury in the Surficial Netserk Sediments
-------
160°
I ' one o* surfeit! sand and gravel due to Nstserk constructor) and erosion
U77 6 to 12 wag-1
¦¦ >12 to 23 ug g'1
Dry weight background As concentration 9 9 ua C'
Figure 1-6. Distribution of Arsenic in the Surficial Netserk Sediments
-------
180°
CD zone of surfciai sand and due to Netaerk constructor* and woson
rm 1 to 2 jjq o*1
¦i 2 tto SBwb tT
Dry weight background Cdoonoentraton
10 PS B'1
Figure 1-7. Distribution of Cadmium in the Surficial Netserk Sediments
-------
285'
270°-
255'
C~3 zone of surficial sand and gravel due to Netserk construction and erosion
EZZ8 19 to 29 7 ug B*1
¦¦ 70 liq g'1
Dry w«ight background Cr concentration 15 0 ug fl"
Figure 1-8. Distribution of Chromium in the Surficial Netserk Sediments
-------
270*
f—3 »ne of aurficia!»and and or»*ei due to Netaark construction and erosion
EZ2 33? to 44 0ug o*'
¦1 466 5iiOQ'4
Dry weight background tooonoantiatcn 202«jg 9*
Figure 1-9. Distribution of Lead in the Surficial Netserk Sediments
-------
—270*
C3 xone of surlicia! sand and gravel due to Netserk construction and arosion
CZZZ) 157 to 213 003*
§¦ 1360 i
-------
BEAUFORT SEA
Figure 1-11. Location Map for Endeavor, Resolution and Challenge Islands*
*From Sohio Alaska Petroleum Company (1982).
-------
'CT2r
ICAlf IM 0
notrm
TfIT PiOT »
KALFCXT Si A
mt kot « • ,mt w ,
• mt put >
• run nor ~
mr nor t » #TfJ, n0T ,
Tut Plot
Latltudc
Lonq itode
Primary Purpose of Site
Mater Der
1
70*27'12"
141*14'5ft*
Deep water below ice disposal site
a.2
2
70*25"31"
14»*15'3a"
Shallow water below Ice disposal site
5.5
3
70"24'34*
14 8*15'22"
Deep water benthic control site
7.4
4
70*27*22*
148*14'01*
Simulated above lee disposal site
4.7
5
70*.25'2i*
146*14'03*
Shallow water benthic control site
4.9
«
70*24'07*
141*15'24"
Offshore above ice disposal site
ft.4
7
70*21'52*
141* 09'26"
Nearshore above ice disposal site
1.0
7A
70* 21'27"
141*10'37"
Nearshore above Ice disposal site
1.0
•
70*25'10*
141*15'30*
Bioassay trailer location (winter)
4.4
*
70*19'00*
148*19'00*
Bioassay trailer location (•uatiter)
NA
10
70*29'09*
141*21'44"
Reindeer Island Hind Sensor Location
NA
(¦)
Figure 1-15. Location Map and Summary of Test Plots for the Study Area*
*From Sohio Alaska Petroleum Company (1981).
-------
• 1ST WEU
.TEST I
TEST HOT 10-WIND SENSOR
*£marr» ts
moss 't
BEAJFORT SEA
i*»to a
TEST KOI 4 - SIMULATED
AftOVE ICE DISPOSAL SITE
¦ TEST HOT 6 - OFFSHORE
AftOVE ICE DISPOSAL SITE
0)23
SCALE IN A
) KILOMETERS
mm. a*)
-NIAKUK ] WELL
TEST PLOT 1 - NEAR SHORE
¦ AftOVE ICE DISPOSAL SITE
- TEST PLOT 7A - NEARSHOtE
AftOVE ICE DISPOSAL SITE
HUXH BAY
Figure 1-16. Location Map for Above-Ice Disposal Tests*
*From Sohio Alaska Petroleum Company (1981).
-------
UI'JD
»*J0 U«*tC
TEST no* 10-WINS SENS0*
»?7»|
•1ST Will
-1 ¦*» ' W «V"W
-.^imay-juit.
y «
MfOC
¦CJi "T\
kaufopt sea
TEST HOT l-DEE* wate»
•ElOw ICI DtS'OSAl sih •
• TEST MOT J - Kf
WAT El CONT*Oi LOCATION
%
TEST >lOT J-SHALLOW WATEI
•ElOW »CE DlS»OSA. SITE » » TEST HOI S - SHALLOW
TEST MOT I - WIND SFNSOt •
lAHll-MAY. 1*7*)
WATE* CONTtOL LOCATION
NIAKlff } WELL
0 12 3
SCALE in
SJiOMTTEtS
y\
NOTE CUUENT MfTilS AT TEST HOTS I AND t
i r ' '— - * ^ ' '
Figure 1-17. Location Map of Test Plots for the Eelov-Ice Disposal Studies*
~From Sohio Alaska Petroleum Company (1981).
-------
BIST WILL
BEAUFORT SEA
TtST nor t - Simulated
A»0VE »CE DISPOSAL SITE ¦ ^ mT n0, , _ WATf#
KiOw iCt DISPOSAL SITE
• TEST HOT ) - DEEP
WATEI CONTICK LOCATION
TEST HOT }- SHALLOW WATER
MLOW ice disposal SITE «
• TEST riOT i - SHALLOW
WATEt CONTtOL LOCATION
TV*?
•VLL IS,
tXlMHDS
nuDHOt may
%
'
I 7 3
P scale in n
KILOMETERS
t
~
— 7C15'
'C*2C
Site Meter Depth
Identif ication (b) Latitude
Longitude Prmary Purpose of Site
Te»t Plot X
Test Plot 2
Test Plot 3
Test Plot 4
Test Plot 5
1.2
5.5
7. t
6.7
4.9
70*27 '12* • 14B*14* 56* Deep water below Ice dispo-
sal site (100 bbl of drilling
fluids discharged on April 22,
1979)
70*25*31* 14B*15'3B* Shallow water below ice dis-
posal site (of drilling fluids
discharged on April 22, 1979)
70*26'34* 148*15'22* Deep water benthic control site
70*27'22* 148*16'01* Sisulated above ice disposal
•ite (100 bbl of drilling
fluids discharged on Hay 6,
1979, 4 bbl discharged through
25 holes.)
70*25'28* 148*14103* Shallow water benthic control
aite
Figure 1-23. Location Map and Summary of Test Plots for
Benthic Studies*
*From Sohio Alaska Petroleum Company (1981).
-------
APPENDIX C.
Summary of Field Studies or Studies
In Situ Describing Metal Bioaccumulntion
Following Exposure to Drilling Fluids
and Cuttings
-------
Studies ia Situ
Single Species Studies
Single species toxicity tests ia situ, have been conducted in Cook Inlet
and in the Beaufort Sea, near Reindeer Island. In the Reindeer Island study
(Sohio Alaska Petroleum Company 1981), amphipods and clams were deployed in
live boxes for 4 days and 89 days. Technical problems (lost or damaged boxes)
prevented any meaningful interpretation of mortality data because of lost
animals and lost control station live boxes. Similarly, the live box arrays
in Cook Inlet (ARCO 1978), using pandalid shrimp, hermit crabs, or pink
salmon fry, also were susceptible to similar techical problems. Meaningful
interpretations from these data are limited in their utility in a hazard
assessment.
Toxicity tests in. situ were conducted in the Prudhoe Bay area of the
Beaufort Sea, near Reindeer Island (Sohio Alaska Petroleum Company 1981).
Live boxes were placed at shallow-water (5.5 m) and deqp-water (8.5 m) below-
ice discharge sites (Tests A and B, respectively) and at a simulated above-ice
disposal site (Test Q. Each box contained 20 amphipods (not specified, but
probably Onisimus and BoeekosiTnuB spp, as for related laboratory tests).
For Tests A and B, live boxes located both at the seafloor and suspended
2.4 m above the seafloor were placed 3 m and 12 m from the discharge and at a
control location. Live boxes were recovered after 97-169 hours. Only
seafloor live boxes were deployed for Test C, and were recovered 94 hours and
89 days after deployment.
Only the bottom live box at 3 m from the discharge (Test B) and the long-
term live box (Test C) showed any mortalities (Table 1-58). Since the live
boxes were recovered intact, it was assumed that amphipods missing from these
tests had been eaten by remaining amphipods. Whether they were affected in
any way by drilling fluids could not be determined.
Metal accumulation also was examined in amphipods deployed in Test C
(Table 1-59). Cr and Zn in disposal site organisms were not different from
controls. Both Cu and Pb showed a 1.3-fold enrichment factor. These factors
-------
are consistent with data obtained from laboratory studies of an Alaskan
species for Cu (1.1-3.1) and for several species tested for Pb (1.2-2.3).
A confounding factor in the Cu data is that although sediment Cu levels
were similar to background levels 3 days after the test discharge, Cu levels
in sediment collected at the recovery of the live boxes were 60-70% above
background levels. It was not known whether the higher sediment levels were
drilling fluid-related.
toother experiment near Reindeer Island was conducted in situ to assess
the potential for long-term impacts from drilling effluents (Sohio Alaska
Petroleum Company 1981). Clam trays were deployed at a control site and at a
simulated above-ice disposal site. Each tray contained 26 clams, including 20
Astarte spp. (ranging in size from 5-20 mm) and 6 Liocyma fluctuosa
(approximately 5 mm in diameter).
Five of 12 trays were recovered during these surveys. Two trays recoverd
96 hours after the simulated above-ice discharge had an average of 1.5 dead
clams per tray. The one tray recoverd at the control site contained two dead
clams. Seven clams were missing from the disposal site trays. None were
missing from the control clam tray.
Approximately 3 months after deployment, only one control clam tray
mortality was observed. Only one tray was recovered from the disposal site.
Ten clams were recoverd aliver nine clams were missing, and the remaining
clams were dead. The tray cover was no longer firmly attached and the tray
contained only about half the original volume of sediment. It was unknown
whether a lack of substrate in the tray or exposure to predation contributed
to the observed mortalities.
A series of 96-hour toxicity tests ia situ has been reported for pandalid
shrimp (Pandalus hypsinotus). hermit crabs (ElasoehHs yini). and pink salmon
fry (Oncorhynchus anrhtiKrha) maintained in live-box arrays near an Alaskan
COST well in Cook Inlet (ARCO 1978). Live-box arrays were located 100 m and
200 m NNE of the rig, along a major current axisr and at a control site some
2 km WNW of the rig.
-------
Field Studies
Gulf of Mexico OCS
A study has provided pre-, during-, and post-operational assessments of
selected biological parameters in the immediate vicinity of an exploratory
drilling rig (Department of the Interior 1976b). The survey was located in 36
m of water on the south Texas OCS, near the north lease line of Mustang
Island, Block 792. Macroepifaunal samples for trace metal and histopathologic
analyses were collected by a semi-balloon trawl. Samples for foraminiferal
analyses were collected by divers using a 10 cm x 0.5 m JVC corer, scraping it
horizontally along the bottom.
The concentration of Cd, Cr, Cu, Fe, Pb, Ni, and V was examined in trawl-
collected samples. These values were comparable to levels in organisms froir.
other areas in the Gulf. The values for shrimp reported in this rig
monitoring study were thought to agree well with levels found in shrimp
"collected~f rom Stati on" 1 on Transect II"
-------
Only two species of penaeid shrimp was collected in sufficient quantities
for histopathological analysis. A total of 150 specimens of Trachvppnapns
Eimilis (25 pre-, 25 during- and 100 post-drilling) were analyzed for evidence
of histopathology.
Tissue sections examined included the cornea, carapace, muscle,
hepatopancreas, kichey, and gonad. Pathology was not detected in any of the
samples. These observations were believed to be unremarkable because these
shrimp were thought to move into and out of the study area. Thus, the same
population was not repeatedly sampled.
Trace metal data from trawl samples do not indicate any systematic pattern
of uptake resulting from drilling activities. Bowever, the selection of
mobile species for tissue analyses limits the general applicability of this
finding. Furthermore, this sampling design does not address this potential
effect in benthic species, which are the more probable sites of impact for
bioaccumulation.
-------
A rig monitoring study was conducted on the couth Texas Outer Continental
Shelf (Department of Interior 1976a). The rig monitoring site (Block 755/
Mustang Island Lease Area) was located between Transects I and II of the STOCS
baseline study area, south of Port Aransas, Texas. The site was located in
33 m of water and was close to the main Port Aransas shipping lane, which was
partially located in Block 755. The rig was on site from December 1, 1976
through January 20, 1977. Drilling began December 3, 1976 and was completed
at a depth of 3352.8 m (11,000 ft) on January 15, 1977.
The pre-drilling survey was conducted September 25-27, 1976. The during-
drilling survey was conducted January 7 and 14, 1977. Post-drilling sampling
occurred February 28-March 2, 1977. Comparisons were made of meiofaunal
abundances per 10 cm^ for five numerous taxa in samples collected in pre-
drilling and post-drilling sampling periods. An increase in the post-drilling
abundances for all groups, except polychaetes, was noted.
The data set on metal levels in epifauna and demersal fishes was
considered to be of very limited use as a means to detect changes..in.tissue
trace metals concentrations resulting from drilling operations. Only three
species were collected both before and after rig operations. Only one species
(Loliffo pealei? squid) occurred in both pre- and post-drilling sample groups.
For this species, modest increases occurred for Cr (> 1.2-fold), Cu (2-fold),
Fe (1.1-fold), Ni (> 3-fold), and V (5-fold). Of these, only Cr, Ni, and V
showed a post-drilling tissue level greater than the mean value + 1 standard
deviation for samples collected on the south Texas OCS, outside the area of
the rig (Table 1-68).
The species analyzed were all mobile. Kie residence time of the organisms
sampled within the immediate vicinity of the rig was unknown but could have
been very limited. Due to seasonal variability in species composition of
epifaunal and demersal fish populations, it was difficult to draw conclusions
on the relationship between drilling activities and trace metal content of the
samples.
-------
Tillery and Thomas (1960) reported a study of the Buccaneer Gas and
Oilfield in the central Gulf of Mexico, which provided 3 years of data on the
chronic, low-level, heavy metal contamination from active petroleum production
platforms on the OCS.
Twenty platform structures and four reference sites (i.e., no structures)
were selected by the Bureau of Land Management (BLM). At least 27 species
were collected and analyzed for trace metals. Of these, only four species
were collected in sufficient numbers to conduct a statistical analysis for
comparison with other literature data. These were Penaeus a2teeus (brown
shrimp), Mieropooon undulatus (Atlantic croaker), Archosarqus prohatoepphainr
(sheepshead) and Qiaetodipfcerus faber (spedefish).
Although these species are very mobile and less than ideal for trace metal
bioaccumulation studies, they were selected because of (1) availability at the
platforms, (2) prohibitive time and cost constraints in implanting and
collecting sessile organisms, (3) availability of trace metal data from the
-literature,-and M-importance^ as-commercial-species.
Trace metal concentrations in muscle tissue of these species did not
generally show significantly higher metal concentrations than similar
organisms from other areas of the Gulf of Mexico. However, concentrations of
Cu and Fe were 1.9-fold and 2.3-fold higher in prohatocephal us; Ni was two-
fold higher. Cu and Fe also were 2.2-fold and 2.1-fold higher in C. faber.
The mobility and limited knowledge of the life cycles of
L prohatocephalus and c. fah^r prevented a definitive correlation between the
concentrations of Cu, Fe, and Ni in their muscle tissues and petroleum
production activities on the OCS. These elevated concentrations only
suggested that the source may be related to petroleum production platforms.
-------
Sohio Alaska Petroleum Company (SOHIO) conducted a study program to
monitor environmental effects associated with above-ice disposal of drilling
fluids and cuttings in the Beaufort Sea (Sohio Alaska Petroleum Company 1982).
These studies were conducted at three well sites: Sagavanirktok Delta wells
17 and *8 (Sag 7 and Sag (8) and Challenge Island well tl (Challenge 1).
At the Sag 7 above-ice disposal site, water depths ranged from 2.9-3.5 m.
At Sag 8 water depths varied from 1.3-1.7 m. Challenge 1 southern disposal
sites (Sites A and B) were located in 2.4-2.9 m of water. The northern
disposal area (Site O was located in water depths that ranged from 2.7-5.0 m.
Approximately 3,000 bbls of saltwater/freshwater lignosulfonate drilling
fluids and cuttings from the Challenge Island well were discharged at the Sag
7 disposal site, during mid-April 1981. Effluents were spread as evely as
possible. Approximately 490 bbl of lightly-treated freshwater lignosulfonate
liquid effluents and 1,670 bbl of fluid solids and cuttings were discharged at
the Sag 8. above-ice disposal site from March 16-30, 19?,!.
Approximately 5,000 bbl of frozen fluids and cuttings were discharged at
disposal sites adjacent to the Challenge Island well from March 14-25, 1981.
At Site A, approximately 1,010 bbl of freshwater drilling effluents were
spread in a layer 2-3 cm thick over most of the disposal site. An additional
250 bbl of drilling effluents mixed with snow were piled in the SE corner of
Site A by end-dumping directly from trucks. Approximately 2,860 bbl of frozen
drilling effluents were spread in a 10-20 cm layer over disposal Site B. At
Site C, approximately 890 bbl of frozen drilling effluents were placed in
piles, nominally 75-90 cm high, to assess the effects of overloading the ice
outside the barrier islands.
Bioaccumulation studies were designed to reveal variations in
concentrations of selected trace metals (Ba, Cd, Cr, Cu, Bg, Pb, Zn) in
benthic and epibenthic organisms during disposal tests. Samples were
collected for these analyses prior to island construction, prior to effluent
disposal, and after effluent disposal. A number of sampling techniques were
used to collect marine organisms for trace metal analyses. During the July,
1980 pre-construction survey, Fonar samplers, pipe dredges, divers, and trawl
nets all were used with limited success.
-------
A disappointing catch of sessile and sedentary benthic organisms suitable
for metal analyses confounded the attempt to implement a valid sampling
program. In view of the substantial efforts expended in sampling with various
methods for these organisms, their abundance was considered low in the
vicinity of the study sites. Since organisms that were collected and analyzed
were primarily motile, individual data points were grouped only by sampling
period and general site.
At Sag 7, samples of isopods fSaduria entomon). sculpin (Mvoxocephalms
guadricornus), and kelp fT-aminaHa sp.) were obtained in July 1980, December,
1980 and July, 1981. Two notable trends appeared in the trace metal analyses
(Table 1-72). First, Ba concentrations decreased considerably in the winter
samples (December, 1980 - January, 1981) in each species. In isopods, Ba
concentrations continued to decrease from December, 1980 to July, 1981. Ba
concentrations in kelp and sculpin. increased from December, 1980 to July, 1981
but mean concentrations remained below that of July, 1980.
^second* trend- appeared in the- trace-metal - concentrations in kelp. From
July, 1980 to December, 1980 all trace metal levels decreased. The
concentration of all metals except Ba and Cr continued to decrease to July,
1981. Other variations in trace metal concentrations in samples from the
vicinity of Sag 7 appeared random.
At Sag 8, with the exception of Zn and Ba, all trace metals increased in
isopods from July, 1980 to July, 1981 (Table 1-73). Sculpin, however,
exhibited a trend in which all metals except Gd decreased from 1980 to 1981.
Samples of kelp, although showing a slight variation, remained statistically
unchanged. Isopods and sculpin at Sag 8 showed a decrease in Ba
concentrations similar to that observed at Sag 7. Also a comparison of July,
1980 and July, 1981 Ba concentrations for both species at Sag 7 and Sag 8
showed that tissue Ba concentrations were lower at Sag 8 in post-discharge
samples. Trace metal levels in isopods from Challenge 1 were lower than those
from the Sag 7 and Sag 8 sites except for Ba, which was higher, and Cr which
was approximately the same.
There are several confounding factors that do not allow these data to
support a conclusion that metal bioaccumulation has not resulted from drilling
-------
fluid discharges. First, data obtained from mobile species may not allow for
valid conclusions in bioaccumulation studies. The concern is that the
mobility of such species is incompatible with identifying effects from a
highly sediment-bound and localized source of exogenous metals. Sessile or
Bedentary benthic epifauna and benthic infauna are more appropriate organisms
upon which conclusions regarding metal accumulation may be made*
Second, the statistical precision of these data does not allow for a
strong reliance on statistical tests to interpret these data (Table 1-74).
Assessing general trends probably is more justified than a rigorous
qualification of the data based on statistical tests. Third, the Ba analyses
may not have measured total Ba levels because of the incomplete extraction
procedures that were employed.
Last, there occurred several notable findings if general trends are
considered. The most obvious trends were noted for isopods. Both whole and
gutted animals (at Sag 7) showed decreased levels of Ba and Cr between pre-
discharge and the first post-discharge samples. This finding is counter-
intuitive "in" view o'fthe faict "that the two metals most clearly and abundantly
related to drilling fluid discharges are Ba and Cr. This finding is made all
the more confusing in that while Ba and Cr were found to decrease, all other
metals examined increased over the same time period.
Since no reference station analyses were conducted by which natural
temporal variations may be factored into an evaluation of these data, it is
difficult, if not impossible to rely on these findings too heavily. Spatial
patterns may have been useful, but given the mobility of the collected
organisms, even a spatial analysis would not be conclusive. These data
suggest that no large amplitude variations in tissue metal levels resulted
from these discharges of drilling fluids, but these data do not address any
lesser level of potential impact.
-------
A study conducted by Crippen et al. (1980) investigated the environmental
levels of metals resulting from drilling fluids discharges to the Beaufort
Sea, near the Mackenzie River Delta. The concentration of metals in the
water, surface and subsurface sediments, and zoobenthos was measured near a
post-operational artificial island drilling site, Netserk F-40. She well was
spudded November 8, 1975 and was completed May 19, 1976. Approximately 7,300
barrels of waste drilling fluids were discharged.
Quantitative benthic samples were collected at 33 stations with a 0.05 m2
Fonar grab that sampled to a depth of 5-10 cm. Samples were sorted using 0.5
mm mesh stainless steel or brass sieves. Each sample consisted of four to
seven Ponar grabs to obtain sufficient biomass for analysis. Duplicate
samples were collected at each station. Extra benthic specimens were
collected at nine stations for metal analyses on purged organisms. These
organisms were purged for 24-48 hours in water from the station at which they
were collected.
Ttii rty-tbree - taxsu - of- .benthic-organisms. we re identified^-to species wht>n
possible—from around Netserk. TheJLowest benthic densities were found at
stations located within 45 m of the island. These densities usually ranged
from 20-450 m~2. At stations 90 m offshore, mean density values of 1100 m~2
were found; densities were 2000 m * at stations 150 m offshore and were
greater than 2500 at stations 300 m offshore and beyond. The stability of
mean densities for these latter stations suggested that they were beyond the
major influences of both the artificial island and the drilling operations.
Benthic biomass, similar to density, was depressed at stations located within
300 m of the island.
The majority of analyses for metals in the benthos were performed on
deposit-feeding infauna. Due to the low benthic biomass, it was necessary to
combine three taxonomic groups (Polychaeta, Oligochaeta, and Felecypoda) to
obtain sufficient tissue for metal determinations. Habitat, niche, and
feeding habits were the criteria chosen for such a classification.
To determine whether sediment chemistry at Netserk had an effect on metal
concentration in infaunal benthic tissue, linear regressions were calculated
for sediment metal concentrations versus benthos metal levels. A linear model
-------
was assumed and an F-test constructed to test for positive correlation between
these paramenters. Both the r-values generated from the F-test (not
significant at the 90% confidence level) and the scattered or randan points on
the graphs in Figure 9 suggest no correlation between metal levels in the
sediment and metal levels in benthic tissue within the study area at Netserk.
The biological impairment (low benthic densities and biomass) that was
noted in the vicinity of Netserk primarily reflected the modification and
smothering of the benthic environment resulting from rapid sediment
accumulation that occurred during island construction and that was occurring
from island erosion during the summer of 1977 .
Erosion of Netserk and the resulting smothering of surrounding sediments
may have had certain advantages. Sediments contaminated with metals from the
disposal of drilling fluids have been diluted and/or buried, thus reducing the
exposure of aquatic organisms to these contaminants. Smothering and
modification of natural marine sediments by the borrow material during
.construction^and subsequent erosion of Netserk probably had a greater impact
to the marine environment than the disposal of drilling fluids.
Two conclusions of this paper, however, are not supported unambiguously by
the data presented. These conclusions were (1) that there were no
correlations between sediment and tissue levels and (2) that biological
alterations were primarily the result of gravel island construction and
erosion.
First, the absence of significant correlations between sediment and tissue
metal levels is compromised by the assumption of a linear relationship. On
the contrary, a linear response is much less appropriate than a log-normal or
a log-log relationship. The absence of significant linear correlations only
provides weak support for the conclusion that no effect occurred. An
additional factor that would substantially contribute to the inability to
detect any correlations between these data sets was the unfortunate necessity
of pooling biological samples among broad taxonomic groups, a requirement that
decreased the statistical resolution possible from these data.
-------
Attempting to identify correlations from visual inspection of graphical
data can be very difficult. From the data provided (Figures 1-24), it appears
that several correlations could be significant if more appropriately
transformed data were analyzed (e.g., As, Gd, Cr). Data on Bg were presented
poorly with regard to scale and difficult to evaluate, although biomass vs
sediment Rg (Figure 1-25) may be better regressed as an exponential decay. Pb
and Zn do not appear to show any correlation between tissue levels and
sediment levels.
Second, the attribution of biological impact to gravel island construction
and erosion also is not unambiguously supported because there were no analyses
that clearly segregated potential drilling fluid impacts from gravel island-
related impacts (for example, clay minerology or Ba content). While the data
suggest on association between island construction/ erosion and biological
impact, data from other studies indicate that discharged fluids and cuttings
may also affect local biological communities. The question of the relative
conributions of these two potential sources of biological impact remains
unresolved.
-------
Table 1-59. Metals Concentrations in taphipods Pran Live Box Test C
At the Simulated Above-Ice Disposal Site (Test Plot 4)
Metals Concentration (iro/ko dry MPiyhM
Exposure Nunber of
Location (days) Organisms Cr Cu R> 2n
Vest Plot 3
87
15
4.6
89
11
99
(Control)
87
16
3.3
90
15
108
Vest Plot 4
89
16
4.6
110
19
114
(Disposal Site)
89
15
3.4
118
15
100
a. Adapted from Sohio Alaska Petroleum Canpany (1981)
-------
Thble 1-68. Trace Metal Levels in Muscle Tissue Pram i/>ll9p
Collected Before and After Drilling Operations8
Tissue levels (ppn dry weioht)
Metal
Before Drilling
After Drilling
BLM-ST0CS
(1976)
Survey
Cd
1.3
0.29
0.18+0.20
Cr
< 0.05
0.06
0.03±0.02
Cu
11
22
13+13
Fe
3.6
4.0
4.6*4.5
Ni
< 0.09
0.27
0.16+0.13
Pb
< 0.03
0.02
0.13+0.10
V
< 0.1
< 0.5
0.2+0.2
Zn
50
43
47±9
a. Adapted from Department of Interior (1976a)
-------
Table 1-72. Trace Metal Levels in Organisms Collected at the Sag 7
Disposal Site®.
Metal (mg/kg)
Sampling ;
Organisn Period . BaCdCrCuBg Fb Zn
Isopods I 790 2.8 8.7 72 0.06 24 99
(whole) II 125 3.2 1.8 82 0.22 49 291
III 121 2.7 4.5 60 0.15 20 68
Isopods I 203 1.6 3.0 36 0.06 11 61
(gutted) II 82 5.3 1.3 52 0.17 12 187
nx ND°
Sculpin I 370 1.3 9.6 13 0.06 9.9 140
(whole) II '33 1.2 2.7 14 0.61 8.2 120
III 166 1.2 3.3 9.1 0.08 9.4 94
Sculpin I 150 1.0 6.3 12 ND 11 80
(gutted) II 50 3.0 2.0 12 <0.01 12 550
HI ND
Kelp I 703 2.5 13 35 <0.01 52 540
II 211 1.6 3.9 16 <0.01 6.9 67
III 303 1.6 5.1 14 0.05 12 54
a. Adapted from Sohio Alaska Petroleum Canpany (1982)
b. Sampling periods: I July 1980
II December 1980 - January 1981
III July - August 1981
c. Not determined
-------
fable 1-73. Trace Metal Levels In Organisms Collected at the Sag 8
Disposal Site®.
Sanpling
Organian Period .
Metal (mgAg)
Ba
oa
Cr
Cu
Bg
R>
Zn
Zsppods
(whole)
I
II
154
38
1.7
3.7
2.3
3.0
66
81
0.11
<0.05
14
22
79
76
Zsopods
(gutted)
I
II
208
3.2
2.2
86
0.15
17
108
Sculpin
(whole)
I
II
71
14
1.4
1.0
2.3
1.8
11
9.4
0.38
<0.05
16
8.7
103
80
Sculpin
(gutted)
I
II
181
1.6
2.5
32
0.14
15
114
Kelp
I
II
282
226
1.6
3.3
5.4
3.9
21
41
<0.25
<0.05
12
15
73
70
a. Adapted from Sohio Alaska Petroleum Corrpany (1982)
b. Sailing periods: I July 1980
II December 1960 - January 1981
c. Not determined
-------
Table 1-74. Statistical Precision of Tissue Trace Metal Determinations
from Organisms Collected at Sag 7 and Sag 8*.
Precision^*
Study ;
Site Ba Cd Cr Cu Bg Fb Zn
Sag 7 158 95 113 89 128 109 155
Sag 8 73 73 111 107 152 71 40
a. Adapted from Sohio Alaska Petroleum Company (1982)
b. Precision expressed as the upper 95% confidence level as a percentage
of the mean.
-------
Table 1-77. Trace Metals in Brittle Stars t-Test for Croup Means of Pre- and Post-Drilling Data
(From Marlanl et al,, 1980)
Tract Nrtiti
l«« if tmOtritlM |m/|)
Oiilmi trtm *11
iltr tor foil-Ortil-
:
¦i«9» if tmwlratlm («|/|l
for Seuthfrn Quatfrailtl
Cwvln* of Southern
Nltfriulf Prf- an*
Orllftaf
Pri-Drillliit
Poil-Dri11inj
iiif Data l»l»n|
-t-ValM
m-Vrlllinf
Fott-Dr tlllnf
t-Vala*
1.10-7*.00
0.80-15.5"
1609
-7.HS*
4.0J-79.00
o.oo-d.io*
-7.90*
lirla
0.45-6.43
1.0-377.6
1609
3.71V
0.S4-6.4}
1.0-139.1
3. TO*
CMal*
<0.0009-70.6
O.I7-I4.771
1609
: 1.75
0.0009-70.60
0.76-14.77
•Ml*
<0.0009-70.6
0.76-14.77
7JI
: 1.39
<0.0009.70.6
0.74-14.77
MS
' 1.76
tkrail*
0.34.1705.00
1609
r 0.77
0.97S-7I.6
0.66-47.4
0.6S
D.l(M)r.»)
OBO-ITOVOO
731
" O.M
0.147-137.703
0.80- 1705.00
MS
1.05
ttfMf
0.00-154.00
0.85-705.97
1609
-3.74*
31.1-146.0
1.06-31.00
•6.00*
laatf
<0.003-5.700
0.10-141.0
l§09
1.13
0.9-4.0
0.1-76.6
0.07
<0.001-5.700
0.I0-I4I.0
711
: I.3S
<0.003-5.700
0.10-141.0
36S
: 1.S4
•tfrwry
<0.009-0.MS
0.0S-II.76
1609
: 7.69*
0.009-0.547
0.95-11.76
7.07*
Hlcltf
4.0-470.0
0.05-755.69'
1609
0.74
0.0-470.0
6.17-110.71
I.M
4.0-470.0
7.69-755.69
7JI
0.46
4.0-470.0
7.69-755.69
MS
0.19
0.56-16.30
0.10 Alt Velvet1
7.07-16.)0
fine
o.7-;M)i.r
I7.0-4.000.0l
1609
0.99
77.7.3570.0
17.0-570.0»
I.IS
4],7-77.879.7
17.0-4,000.0
731
0. 7ft
41.7-77,(179. 7
17.0-4.000.0
365
0.54
•Significant at •• o.os.
vtlwt illf l*t« Itw Prr-Drfttlnf
-------
Table 1-78. Trace Metals in Polychaetes t-Test for Group Means of Pre- and Post-Drilling Data
(From Marianl et al.( 1980) }
i
Tr#t* Mrtalt
¦tuff of Concentre! lani (114/q)
Wf-Or 111 inf Poif-Dr ' 111PHJ
Olltincr trim Veil
SMe tor Poit-Ortll-
Inj Oil# |M»ri >
t-¥»1oe
•tit;* of Cnnctnlnt lout (tqlj)
for Southern Ondtrcntf
•—PFrtirmini —P6it-B>Trrnr?
CmtrllW 07 SMltWrn
Qu*dr«ntt h»- W>< fMl-
OrtlllM Dlt*
t-»«loe
•riralc
0.76-7.1
0.10-1.71'
1809
1.78
0.76-1.70
0.I0-I.7I1
0.53
0.76-7.1
0.10-1.70
711
1.4)
0.76-M
0.10-1.IS
16S
I.3S
¦•rlva
<1.0-73.35
0.30-476.4
1609
7.4|«
<1.0-73.35
0.3-476.4
I.7S
Citilw
0.73-5.579
0.31-16.10
1609
0.77
0.73-4.17
0.38-16.18
0.85
0.73-5.579
0.31-16.18
7JI
I.OB
0.73-5.579
0.31-16.IS
365
0.95
Oirt»lM
<0.01-0.65
0.40-69.7
1609
3.87*
<0.01-0.56
0.40-69.7
Cepwr
l.rs.7«.i
0.|4.?J.36>
1609
-7.66*
1.75-74.1
0.08-6.01'
i«*d
<0.00J-57.0
0.10-17.50'
1609
1.66
<0.003-74.6
0.10-17.5'
0.05
<0.001-57.0
0.10-17.50
731
1.37
<0.003-57.0
0.10-17. SO
3»S
1.11
•Vrenrjr
<0.009-0.19
0.05-1.88
1609
• . 34*
<0.009-0.390
0.05-1.00
1.95
Nlckft
1.7-746.0
0.54-97.79'
1609
1.97
1.7-746.0
0.89-97.79'
1.1)
1.7-746.0
0.54-97.79
7)1
1.61
l.f-Mt.O
0.54-97.79
365
1.13
<1.0-8.5
0.10-71.84
1609
3.76*
1.1-7.3
0.10-73.04
1.00
Unc
64.|9-8r>7.0
IJ.0-1881.0
1809
1.84
. 84.19-007.1
104.0-1601.0
1.35
64. 19-007.0
1).0-1681.0
7)1
1.57
64.19-807.0
IJ.0-1681.0
)65
1.4)
Mlfiiiricfnt at a • 0.05
*''wt-0r IIIIbj dim 9«nrr«t1jr Irii th«n N-Drllllr; vtlutt.
-------
Table 1-79. Trace Metals In Brittle Stars t-Test for Group Means of Pre- and Post-Drilling Data
(From Marlani et al., 1980)
law a* CmtwtritlM (*«/«)
(ItlMt frai Wall
$lt« for Fott-Orltl
iwfi •* (miMritiiM tmW
lor SaalNrn 0»a#rawtt
fmarlit* af SaatHarw
Qlttrnll »r«- M t(lt>
Or It Km iata
Tract Natal*
Frf-Mlll",
Pdft-Dr111iDf
Inf Oat* (Nrliri)
t-fateo
Frt-Ortllinf
Foil-ur llllitf
t-vaiw
friwlt
0.H-7.I0
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-------
BENTHOS VS SEDIMENT
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-------
MOD.08O ,
DEUSITi VS 5EPImEnt
DENSITY VS SEDIMENT
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SCOIMEHT MEftCUftT •uti>4T)f«i|m
Figure 1-25. Comparison of Mercury Concentrations in Sediments
with Benthic Density and Biomass at Metserk F-AO*
*From Crippen et al. (1980).
-------
• »
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Figure 1-26. Location of Benthic Samples and Geographic Grouping of
Infaunal Samples from the June 1977 Survey*
*From Lees and Haughton (1980).
-------
APPENDIX D.
Summary of Cadmium and Mercury Content
in Generic Drilling Fluids
-------
Table 1. Mercury and Cadmium Analyses of
Alaskan Generic Drilling Muds (1983-1984)
Location
1/
Gulf—Cross Island —'
1/
Sohio—Mukluk Island —'
Shell—Seal Island —
2/
ARCO—Kenai Peninsula —'
(onshore)
Mud Type/Density
(lb/gal)
Seawater
lignosulfonate/13
Seawater
lignosulfonate/10
KC1/10.2
KC1/10
KC1/13
Hg (mg/kg, Cd (mg/kg,
dry wt.) dry vt.)
0.102
0.24
0.05
0.16
0.001
1.36
0.635
1.21
0.05
1.1
^1End-of T-well .analy.ses.. conducted. and reported- in - accordance with EPA
Region 10 NPDES permit requirements.
2 To EPA Region X
-------
Table 2. Mid-Atlantic Generic Mud Program
Mud Type Cd (ppm) Hg (ppm)
Mud #1
KC1 Polymer Mud 1 5
Mud #2
Seavater Lignosulfonate Mud <1 <1
Mud #3
Lime Mud <1 <1
Mud #4
Non-Dispersed Mud <1 <1
Mud #5
Seawater Spud Mud <1 <1
Mud #6
Seawater/Freshwater Gel Mud_. .<1 <1
Mud #7
Lightly Treated Lignosulfonate <1 <1
Freshwater/Seawater Mud
. , , , . . .. « * 3 - —
Mud #8
Lignosulfonate Freshwater Mud <1 <1
-------
Table 3. EPA PESA Generic Mud Program
Generic
Mud Number
Cd mg/kt?
He me/kB
008-00
.365
.343
002
.471
.2639
007
.143
.1386
001
.22
.2606
005
.074
.0100
006
.0425
.2969
003
.378
.7530
004
.446
.4374
-------
Table 4. Southern California Generic Muds Analysis*
Drilling Mud
Identification Code
2 REV073
4 REV073
Cd (mg/kg) Hg (mg/kg)
0.10 0.015
0.10 0.013
* Report from Pacific Environmental Laboratory to EPA Region IX, reported
October 20, 1983.
-------
APPENDIX E.
Cadmium Contents
in Non-Generic Drilling Fluids
-------
Table 1.
EPA Gulf of Mexico Non-Generic
Drilling Mud Program
Mud Identification Cd (vg/g dry veight) Hg (vg/g dry weight)
Number
MIBLKA51
.387
N.D
AN31-1-6
2.38
N.D
MILGEL
.494
N.D
SV76-2-5
1.62
N.D
Pl-1-3
1.85
N.D
P2-1-3
11.8
N.D
P3-1-3
2.10
N.D
P4-1-3
8.27
N.D
P5-1-3
2.34
N.D
P6-1-2 '
10.5
N.D
P7-1-2
.21
N.D
P8-1-1
.410
N.D
N.D. - Not Determined
-------
APPENDIX F.
Comments on Testimony of Dr. Jerry Neff
to EPA Region X on Proposed BPJ Permits
-------
Appendix F
Comments on Jerry Neff Testimony to Region X on Proposed
BPJ General Permits
1. Metallic Impurities in Barite
In this section, on page 2, Neff discusses the difference between
bedded deposits of barite and vein and cavity-filling deposits noting that
bedded deposits are usually much purer than the vein and cavity-filled
type. Concentrations of cadmium and mercury may vary by more than ten-
fold depending on the source of the barite.
Because of this distinction Neff rightly notes that the bedded de-
posits, particularly those clean deposits from the Battle Mountain
area of north-central Nevada, are the preferred source of barite for
muds on the U.S. outer continental shelf.
In this section, Neff is verifying that there are "clean" and "con-
taminated" barite, and that (1) it is technologically feasible to limit
the amount of cadmium and mercury discharged, and that (2) whatever hazard
exists can be reduced in this manner.
2. Fate of Discharged Barite
In this section, Neff makes the statement that, "Barium concentrations
may reach 10 to 20 times above background in sediments near the discharge."
What he does not make clear is that this is true only for exploration.
Although he notes several situations where barium concentrations have been
found to be much higher than background, he does clearly state that
during development barium concentrations can reach 100 timesbackground or
more.
3. Long-Term Accumulation of Cadmium and Mercury in Sediments
A) In the first paragraph of this section Neff states that "...
drilling fluid solids average 60 percent barite by weight." This
is not accurate. Barite might average 65 percent of all drilling
-------
fluids, including both soluble and particulate additives by weight,
but it is more likely to approximate 80 percent barite by weight of
mud solids.
B) Neff goes on to predict that, "In the next ten years, if all the
wells projected by MMS are drilled, 320,300 metric tons of drilling
mud solids containing 192,180 metric tons of barite will be discharged.
The discharged barite will contain 192 kilograms of cadmium and 95 kilo-
grams of mercury." These concentration figures are calculated using
low and/or unrealistic numbers. First, they are based on the 60 percent
barite figure which we have previously discussed as being too low. Also,
they are based on low estimations of the concentrations of cadmium and
mercury in the barite. In fact, Neff uses values even lower than those
proposed in the draft permits. Neff assumes an average of 1 ppm cad-
mium and 0.5 ppm mercury in barite by weight. Neff's Table 1 shows
these figures to be on the low end of the spectrum, which averages
approximately 3 ppm cadmium and 1.6 ppm mercury and has a maxima of
16 ppm cadmium and 13 ppm mercury. Using these figures to calculate
the amount of cadmium and mercury discharged in the next ten years
portrays a different scenario, as shown below:
CADMIUM MERCURY
minimum average maximum minimum average max'tumm
Assume Assume
60% barite 192 kg 576 kg 3072 kg 60% barite 96 307 2496
Assume Assume
80% barite 256 768 4096 80% barite 128 409 3328
C) In this section Neff goes on to compare the amounts of suspended
solids discharged into coastal and outer continental shelf waters by
rivers and by drilling operations. He states, "If the suspended sedi-
ments discharged by the rivers contain 1.0 ppm cadmium and 0.1 ppm
mercury (Based on ambient levels in clean surfical sediments of the
area Table 2), a total of 142 metric tons of cadmium and 14.2 metric
tons of mercury will be introduced to coastal waters each year in
river-borne particles."
-------
There are a number of points confounding this observation. The first
is that one cannot assume that marine sediment metal levels and river sediment
levels are the same, which he does by using the figures from Table 2.
Also, 5 out of 6 of the Alaskan sites mentioned in this Table are in the
Beaufort Sea, which is a highly erosional area. Therefore, surfical
sediments can be higher due to simple coastal erosion. The
relative contribution of river inputs versus marine sediments in_situ is
unknown.
Neff also assumes that the river contribution to background levels is
all natural. In most areas this cannot be assumed because rivers are
often affected by man's activities. For instance, in many Alaskan and
Canadian rivers, the effects of placer mining would be difficult to dis-
tinguish from natural background levels. Even if natural levels are high,
it does not necessarily follow that no regulation is needed. It has been
previously noted that mercury levels in whales taken as subsistence catch
is already high. This may well be due to natural causes. However, this
finding could be interpreted as making a reduction in any anthropogenic
sources of metal pollutants even more necessary precisely because of high
natural inputs.
Finally, EPA Effluent Guidelines Regulations are based on technologic
feasibility and not on the basis of industrial versus "natural" sources
of pollution. This is particularly relevant considering that it is difficult
to determine "natural" background levels.
4. Mobilization of Cadmium and Mercury from Barite
In this section Neff notes that, "In 6eavater equilibrated with high
trace metal vein barite, the concentration of soluble mercury was signifi-
cantly higher than open ocean concentrations. Addition of bentonite clay
(a normal ingredient of drilling muds) reduced aqueous mercury concentra-
tions to below oceanic levels." What is happening in this situation is that
with the addition of bentonite clay,the metals are re-distributing
to the sediment with the clay.
Neff further notes here that ". . • a maximum of 4 percent of the
cadmium and 0.4 percent of the mercury originally present in the barite
-------
was solubilized in 12 days." This statement is confusing because later
in the section he refers to an Espy Houston and Associates study by
saying, "These studies show that cadmium sulfide and mercuric sulfide
associated with barite are not readily solubilized." The confusion may
be in the definition of the term readily; however, referring to the
previous 12-day estimate, this seems to be a short amount of time when com-
pared to the time the metals will stay in the system.
In the last paragraph of this section Neff furthers his contention that
the leaching rate of cadmium and mercury in sediment is so slow as to pre-
clude biological damage. Although it is certainly true that solids reduce
the uptake of these metals, they certainly do not prevent it and not
enough to conclude a preclusion of biological damage. To illustrate this
point we consider Hardy et al's study of "Marine Sediment and Interstitial
Water." Figure 3 of this study shows the accumulation of cadmium by gills
of the Clam Protothaca staminea to be reduced by the addition of sediment.
However, even in this case, with an addition of washed sediment bringing
the sediment:cadmium ratio to 100,000:1 accumulation is reduced by only
80%.
The evidence cited in this section supports EPA's efforts to regulate
barite discharges since there are data that support a potential for environ-
mental impacts.
5. Bioavailability of Cadmium and Mercury from Barite
In this section Neff cites Gerber et al (1981) on accumulation of cad-
mium by sand shrimp and mussels, Tornberg et al (1980) on accumulation of
cadmium, chromium, lead and zinc by amphipods, Crippen et al (1980) and
Tillery and Thomas (1980) on metal concentrations in sediments and biota,
and Mariani et al (1980) on concentrations of metals in sediments and
benthic invertebrates. For an alternate interpretation of this data
see Petrazzuolo (1981, 1983) (See also Appendix A). It should also be
noted that Espy Houston and Associates, Inc. (1981) which Neff cites in
the beginning of this section, has not been published.
6. In conclusion, in light of limited lab and field data showing accumu-
lation (see Brannon and Rao, Table 1-55), to say there is "no hazard
-------
whatever to the marine environment from cadmium and mercury present as
insoluble sulfides in barite" is hasty and not supported by the data.
Neff has used lab studies that were limited or that used wrong test
phases. He has used data from exploratory operations only; and in short,
is not looking closely enough at the end-point of biological uptake, but
is predicting effects on the basis of physical-chemical principles that
are attractive in theory, but which are not supported by bioaccumulation
data. The best example of this latter situation is Ba uptake from
exposure to BaS04, a notably "insoluble" material. Nonetheless, despite
the low predictable uptake on the basis of physical-chemical data, high
levels of Ba were found in hard and soft tissues of shrimp exposed to
barite for three months (Brannon and Rao).
-------
APPENDIX G.
Trace Metal Content of
"Clean" and Contaminated Barite
-------
Table 2. Composition of barites used in
solubility studies.*
High trace Low trace
metal sample metal sample
Ni mg/kg
33
5.7
Cu mg/kg
91
7.6
Cd mg/kg
12
0.65
Co mg/kg
5.4
2.2
Zn mg/kg
2750
9.8
Pb mg/kg
1370
0.95
Hg mg/kg
8.1
0.13
As mg/kg
67
1.8
BaS04 %
85.1
-
Sr mg/kg
- -
540
LOI %
0.3
-
Si02 %
6.2
8.2
MnO %
o
t
V
<.04
Fe203 %
3.1
0.60
MgO «
1.3
<.1
CaO %
1.9
0.3
k2o %
0.08
0.08
* frpm Kramer et al. 1980
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