United States
Environmental Protection
Agency
Office of Water
Mail Code 4303
Washington, DC 20460
EPA-821-B-00-014
December 2000
EPA
Environmental Assessment of Final
Effluent Limitations Guidelines and
Standards for Synthetic-Based Drilling
Fluids and other Non-Aqueous Drilling
Fluids in the Oil and Gas Extraction Point
Source Category
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Acknowledgments
This report was prepared by Charles Tamulonis and Marvin Rubin of the Engineering and
Analysis Division. Assistance was provided by Nerija Orentas and Richard Montgomery of
Avanti Corporation. References to proprietary technologies are not intended to be an
endorsement by the Agency.
Questions or comments regarding this report should be addressed to:
Charles Tamulonis, Environmental Engineer
Engineering and Analysis Division (4303)
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, N.W.
Washington, DC 20460
(202) 260-7049
tamulonis.charles@epa.gov
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CONTENTS
EXECUTIVE SUMMARY ;.-. ES-1
1. INTRODUCTION : ;\ ...... 1-1
2. DESCRIPTION OF REGULATORY OPTIONS 2-1
3. CHARACTERIZATION ,••
3.1 Industry Characterization.... • 3-1
3.2 Wastestream Characterization 3-4
3.3 Receiving Water Characterization 3-8
3.3.1 Gulf of Mexico -3-8
3.3.2 Cook Inlet, Alaska .r........'.".' - . Y..;... 3-10
3:3.3 Offshore California "..Y - .".'.' 3-11
3.4 Recreational and Commercial Fisheries 3-12
3.4.1 Gulf of Mexico vY.. 3-12
3.4.2 Cook Inlet, Alaska . .Y;;.. , • • 3-13
3.4.3 Offshore California , • 3-15
4. WATER QUALITY ASSESSMENT
4.1 Introduction .-.V.; 4-1
4.2 Surface Water 4-2
4.2.1 Gulf of Mexico " 4-5
4.2.2 Cook Inlet, Alaska .._.,. • 4-7
4.2.3 Offshore California .; ."• • ... 4-7
4.3 Sediment Pore Water Quality 4-10
4.3.1 Gulf of Mexico - - 4-10
4.3.2 Cook Inlet, Alaska and Offshore California '. 4-15
4.4 Sediment Guidelines for the Protection of Benthic Organisms 4-16
5. HUMAN HEALTH RISKS ••-—
5.1 Introduction .-.-..--. • • 5-1
5.2 Recreational Fisheries Tissue Concentrations 5-1
5.2.1 GulfofMexico • • 5-3
5.2.2 Cooklnlet,Alaska .-.._-._ _• • • • 5-3
5.3 Commercial Fisheries ShrirhpTissue Concentrations • • • • 5-4
5.3.1 GulfofMexico 5-7
5.3.2 Cooklnlet, Alaska 5-7
5.4 Noncarcinogenic and Carcinogenic Risk - Recreational Fisheries ............ 5-7
5.4.1 GulfofMexico ... 5-10
5.4.2 Cooklnlet, Alaska 5-10
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5.5 Noncarcinogenic and Carcinogenic Risk - Commercial Shrimp 5-10
5.5.1 Gulf of Mexico 5-12
5.5.2 Cook Inlet, Alaska 5-12
6. TOXICITY
6.1 Introduction 6-1
6.2 Summaries of Identified Articles Containing Toxicity Information 6-2
6.3 Summary 6-15
7. BIOACCUMULATION
7.1 Introduction 7-1
7.2 Summary of Data 7-1
7.3 Summaries of Identified Reports Containing Bioaccumulation Information 7-2
8. BIODEGRADATION
8.1 Introduction 8-1
8.2 Biodegradation Test Methods 8-1
8.3 Biodegradability Results 8-8
8.3.1 Aqueous Phase Tests 8-8
8.3.2 Sedimentary Phase Tests 8-10
8.4 Discussion and Conclusions 8-14
9. SEABED SURVEYS
9.1 Background 9-1
9.2 . Assessment of Field Studies 9-2
9.2.1 Findings 9-2
9.2.2 Study Limitations 9-15
9.3 Summary of Relevant Field Studies 9-18
9.3.1 Water-Based Fluids 9-18
9.3.2 Synthetic-Based Fluids 9-44
10. BIBLIOGRAPHY 10-1
Appendix 3-1 Calculation of Gulf of Mexico Shrimp Catch A-l
Appendix 4-1 Gulf of Mexico Surface Water Quality Analysis A-3
Appendix 4-2 Cook Inlet, Alaska Surface Water Quality Analysis A-7
Appendix 4-3 Offshore California Surface Water Quality Analysis A-l 1
Appendix 4-4 Gulf of Mexico Sediment Pore Water Quality Analysis A-15
Appendix 4-5 Cook Inlet, Alaska Sediment Pore Water Quality Analysis A-22
Appendix 4-6 Offshore California Sediment Pore Water Quality Analysis A-26
Appendix 4-7 Gulf of Mexico Sediment Guidelines Analysis A-30
Appendix 4-8 Cook Inlet, Alaska Sediment Guidelines Analysis A-34
Appendix 4-9 Offshore California Sediment Guidelines Analysis A-3 6
Appendix 5-1 Offshore California Human Health Risk Analysis A-3 9
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Ill
Appendix 5-2 Gulf of Mexico Recreational Fisheries Human Health Risk Analysis A-52
Appendix 5-3 Cook Inlet, Alaska Recreational Fisheries Human Health Risk Analysis . A-59
Appendix 5-4 Gulf of Mexico Commercial Fisheries Human Health Risk Analysis .... A-66
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IV
EXHIBITS
Exhibit ES-1 Summary of Pore Water Quality Analyses Fluid ES-4
Exhibit 3-1 Estimated Number of Wells Drilled Annually By Drilling Fluid 3-3
Exhibit 3-2 Volume of SBF-Cuttings Generated Per Model Well- 3-6
Exhibit 3-3 Model Well Characteristics 3-8
Exhibit 3-4 Heavy Metal Concentrations In Barite 3-9
Exhibit 3-5 Formation Oil Characteristics 3-10
Exhibit 3-6 Gulf of Mexico Recreational Fisheries Catch 3-13
Exhibit 3-7 Gulf of Mexico Commercial Shrimp Catch 3-14
Exhibit 4-1 National Recommended Water Quality Criteria for SBF Pollutants 4-3
Exhibit 4-2 Summary of Water Column Water Quality Analyses 4-6
Exhibit 4-3 Applicable Alaska State Water Quality Standards 4-8
Exhibit 4-4 Enforceable Alaska State Standards Under the Clean Water Act 4-9
Exhibit 4-5 Summary of Pore Water Quality Analyses - Factors by Which
Criteria are Exceeded 4-11
Exhibit 4-6 Summary of Synthetic Base Fluid Concentrations at 100 Meters 4-13
Exhibit 4-7 Trace Metal Leach Factors and Organic Pollutant
Partition Coefficients 4-15
Exhibit 4-8 Summary of Sediment Guidelines Analyses 4-18
Exhibit 5-1 Pollutant-Specific Bioconcentration Factors 5-3
Exhibit 5-2 Calculation of Average Dilutions within Gulf of Mexico Mixing Zone .... 5-4
Exhibit 5-3 Calculation of Average Dilutions within Cook Inlet, Alaska
and Offshore California Mixing Zones 5-5
Exhibit 5-4 Arithmetically-Averaged Concentration Data 5-6
Exhibit 5-5 Oral Reference Doses and Slope Factors 5-9
Exhibit 5-6 Summary of Finfish Health Risks 5-11
Exhibit 5-7 Summary of Shrimp Health Risks 5-13
Exhibit 5-8 Calculation of Shrimp Catch Impacted in the Gulf of Mexico 5-14
Exhibit 6-1 Reported Toxicities of Synthetic-Based Fluids 6-4
Exhibit 6-2 Minimum and Maximum LC50 Values for New Sediment Toxicity Data Presented
as Comment Response on Either the Proposed Rule (12/99) or the Notice of Data
Availability (4/00) for Effluent Limitations Guidelines for the Oil and Gas
Extraction Point Source Category 6-7
Exhibit 6-3 Discriminatory Power Values Between LC50 Values for New Data Comparing
Base Fluids and Diesel. Discriminatory Power Is Defined as the LC50 Values of
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Base Fluids Divided by the LC50 Values of Diesel. Tests Were Conducted with
Both Natural Sediment (NS) and Formulated Sediment (FS) and for a Duration of
96-hours (96h) and 10-days (lOd) 6-13
Exhibit 6-4 Discriminatory Power Values Between LC50 Values for New Data Comparing
Base Fluids. Discriminatory Power Is Defined as the LC50 Values of Best
Performing Base Fluids Divided by the LC50 Values of Other Base Fluids in the
Study. Tests Were Conducted with Both Natural Sediment (NS) and Formulated
Sediment (FS) and for a Duration of 96-hours (96h) and 10-days (lOd). .. 6-14
Exhibit 7-1 Bioaccumulation Data for Synthetic Fluids and Mineral Oil Muds 7-3
Exhibit 8-1 OECD 301D: 28-Day Closed Bottle Test 8-2
Exhibit 8-2 ISO 11734: "Water Quality-Evaluation of the "Ultimate" Anaerobic
Biodegradability of Organic Compounds in Digested Sludge-Method
By Measurement of the Biogas Production" 8-4
Exhibit 8-3 NTVA Protocol for Simulated Seabed Biodegradation Study 8-5
Exhibit 8-4 SOAEFD Protocol for Solid-Phase Test System for Degradation
of Synthetic Mud Base Fluid 8-5
Exhibit 8-5 Summary of Aquatic Phase Aerobic Laboratory Biodegradation Test
Conditions and Their Suitability for Poorly Soluble, Volatile, and
Surface Active Compounds 8-6
Exhibit 8-6 Summary of Test Procedures Used in the Biodegradation Testing
of Synthetic-Based Drilling Fluids 8-7
Exhibit 8-7 Ranking of Aqueous Phase Biodegradation Methods and Test Results 8-9
Exhibit 8-8 Average Percentage Biodegradation Using BODIS Seawater and
Freshwater Procedures for an Ester and Acetal 8-9
Exhibit 8-9 Anaerobic Biodegradability of Test Chemicals Examined in the
ECETOC Screening Test 8-10
Exhibit 8-10 Percentage Biodegradation of Base Fluids in Drilling Fluids Measured
by Various Test Methods 8-12
Exhibit 8-11 Percentage Biodegradation of Base Fluids Conducted by U.S. EPA Using the
SOAEFD Method 8-13
Exhibit 8-12 Percentage Biodegradation of Base Fluids Conducted by Oil and Gas Industry
Usingthe SOAEFD Method 8-15
Exhibit 9-1 Marine Studies of Water-Based Drilling Fluid Impacts 9-4
Exhibit 9-2 Marine Studies of Synthetic-Based Drilling Fluid Impacts . 9-9
Exhibit 9-3 Water-Based and Synthetic-Based Drilling Fluid Impact Comparison .... 9-15
Exhibit 9-4 Comparison of Sampling Area of Averages for Number of Species,
Organisms, and Species Diversity for the Survey Periods 9-25
Exhibit 9-5 Summary of Benthic Data Collected at Test Plots 9-30
Exhibit 9-6 Comparison of Abundance Data Collected at Test Plots 9-30
Exhibit 9-7 1990 and 1991 North Sea Benthic Community Data 9-45
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Exhibit 9-8 Sediment TPH vs. Distance from Drill Site 9-47
Exhibit 9-9 Sediment Barium vs. Distance from Drill Site 9-47
Exhibit 9-10 Abundance and Diversity Data From Norwegian Drilling Fields 9-57
Exhibit 9-11 Summary of Benthic Data for Two Gulf of Mexico Platforms 9-59
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ES-1
EXECUTIVE SUMMARY
A. Background
This environmental assessment consists of an evaluation of the ecological and indirect
human health impacts for the discharge of cuttings contaminated with synthetic-based drilling
fluids (SBFs) with respect to discharges to water. In addition, this document describes the
environmental characteristics of SBF drilling wastes (e.g., toxicity, bioaccumulation,
biodegradation), the types of anticipated impacts, and the pollutant modeling results for water
column concentrations, pore water concentrations, and human health effects via consumption of
affected seafood. •
The geographic areas considered under this analysis are those where EPA knows SBFs are
currently used and those where EPA projects SBFs will be used as a result of the SBF Effluent
Guidelines. This includes the Gulf of Mexico and Cook Inlet, Alaska. EPA considered Offshore
California but industry currently projects that even if SBF controlled discharges are allowed under
effluent guidelines, operators would not discharge SBF-cuttings. Thus, EPA projects that pollutant
loadings will change in the Gulf of Mexico and may change in Cook Inlet, Alaska as a result of the
final rule. It is only these two regions that are included in the various environmental impact
analyses of this environmental assessment.
EPA considered three BAT regulatory options for the SBF rule: two controlled discharge
options and a zero discharge option. While discharge of SBF-cuttings would be allowed under the
discharge options, discharge of SBFs not associated with drill cuttings would not be allowed.
Since zero discharge of neat SBFs is also current industry practice due to the value of SBFs
recovered and reused, it has no incremental environmental impact.
In the zero discharge option, both the SBF-cuttings as well as neat SBF would be prohibited
from discharge. Because the zero discharge option results in the absence of discharged pollutants,
the environmental assessment analyses did not require calculations to demonstrate zero
environmental impacts.
For the purposes of this environmental assessment, EPA projected that the only material
effect that the discharge options would have on the SBF-cuttings wastestream would be to change
the type of SBF drilling fluid that would be allowed and to reduce the amount of synthetic base
fluid on the drill cuttings from 10.2% to 4.03% for the first discharge option and from 10.2% to
3.82% for the second discharge option. This reduction is based on the performance of the current
shale shaker technology (10.2% base fluid retention) and the BAT technology options (4.03% or
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ES-2
3.82% base fluid retention) for those SBF that are acceptable for discharge based on their lower
sediment toxicity and higher biodegradation rates. The model BAT technology for complying with
the retention on cuttings limitation consists of cuttings dryer and fines removal units which recover
additional SBF from the SBF-cuttings. For the purpose of this environmental assessment, EPA
does not evaluate the effect of the other proposed limitations, such as the stock base fluid
limitations.
Thus, for the purpose of this analysis, under the discharge option, the amount of pollutant
discharge is reduced but the types of pollutants are not affected. Also, EPA projects that the
number of wells using SBF will increase. In the Gulf of Mexico, EPA projects that under current
requirements 201 SBF wells annually will be drilled in the Gulf of Mexico, while under both of
the discharge options 264 SBF wells will be drilled annually. Since all of the analyses, except for
exposure by way of shrimp consumption, are on a site specific basis, the number of wells
discharging does not affect the conclusions of this environmental assessment. Only the quantity
and types of pollutants discharged at a particular site affect the conclusions (except shrimp
consumption analysis).
The current limit for SBF cuttings generated in Cook Inlet is zero discharge. Zero discharge
is also current industry practice in that region. However, if operators can demonstrate to the
permitting authority that they can not zero discharge their waste they may apply for permission to
discharge. Therefore, for purposes of this environmental assessment, potential impacts from the
two controlled discharge options are presented for Cook Inlet, Alaska.
Recent industry information provided to EPA projects that under a SBF cuttings discharge
scenario, some wells currently drilled with WBFs would switch to SBF use due to greater drilling
efficiency of SBFs compared to WBFs. EPA estimated that under either of the discharge options,
less pollutants would be discharged compared to baseline current practice because drilling with
SBFs reduces washout, resulting in a smaller hole volume. Also, SBF cuttings would be
discharged as opposed to both fluids and cuttings when WBFs are used. Clearly, the lower
pollutant loadings resulting from SBF versus WBF usage would reduce the environmental impacts
of drilling discharges. However, this environmental assessment does not quantify the benefit of
SBF use. Pollutant and non-water quality impact reductions are discussed in the final SBF
Development Document.
. The amount of pollutants discharged and impacting the receiving water depends on the
efficiency of the solids control equipment, here expressed as either 10.2%, 4.03% or 3.82%
retention on cuttings, and the volume of cuttings generated from drilling a given well or well
interval.
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ES-3
EPA has adopted the Minerals Management Service (MMS) and industry categorization of
drilling wells according to type of drilling operation, i.e., exploratory or development, and water
depth. Deep water wells are defined as wells that are drilled in water greater than 1,000 feet deep
whereas shallow water wells are drilled in water less than 1,000 feet deep. Using other federal
and state government agency data, EPA determined the number of wells drilled annually using
SBFs, OBFs, and water-based drilling fluids (WBFs).
B. Water Quality Assessment
EPA modeled the incremental water column and pore water concentrations and comparing
them to recommended Federal water quality criteria/toxic values for marine acute, marine chronic,
and human health protection. Additionally, EPA used the proposed sediment guidelines for
protection of benthic organisms to assess potential impacts from a group of select metals in pore
water. Note that all of these comparisons are performed only for those pollutants for which EPA
has numeric criteria. Those pollutants include priority and nonconventional pollutants associated
with the drilling fluid barite and with contamination by formation (crude) oil, but do not include
synthetic base fluids themselves. Results of the water quality analyses for the Gulf of Mexico and
Cook Inlet show that there are no exceedances of Federal water quality criteria in either the
current technology (10.2% retention) or the two discharge option (4.03% and 3.82% retention)
scenarios.
Exhibit ES-1 presents a summary of the pore water quality analyses where exceedances are
expressed as multiplied factors of the Federal water quality criteria. Compared to current
technology, the projected number and magnitude of water quality criteria exceedances decreases
under the discharge options. In the Gulf of Mexico, three of the four model wells (shallow water
exploratory, deep water development, and deep water exploratory) fail to meet the sediment
guidelines under the baseline scenario using the current technology (see Table ES-1). Under the
discharge options, all model wells meet the guideline. For Cook Inlet, Alaska, the deep and
shallow development model wells pass the guidelines under the discharge options. EPA does not
anticipate that exploratory wells will be drilled in Cook Inlet.
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ES-5
C. Human Health Effects
This portion of the environmental analysis presents the human health-related risks and risk
reductions (benefits) of baseline using current technology and the discharge regulatory options.
EPA based the health risks and benefits analysis on human exposure to carcinogenic and
noncarcinogenic contaminants through consumption of affected seafood; specifically,
recreationally-caught finfish and commercially-caught shrimp. EPA used seafood consumption
and lifetime exposure duration assumptions to estimate risks and benefits under the current
technology (10.2% retention) and discharge options (4.03% and 3.82% retention) scenarios for the
two geographic areas where the quantities of SBF-cuttings discharged will be affected by this rule.
The analysis is performed only for those contaminants for which bioconcentration factors, oral
reference doses (RfDs), or oral slope factors for carcinogenic risks have been established. Thus,
the analysis considers contaminants associated with the drilling fluid barite and with
contamination by formation (crude) oil, but does not consider the synthetic base compounds
themselves.
In order to derive the risks due to consumption of contaminated seafood, EPA first
determined the concentration of contaminants in finfish and shrimp tissues. Finfish tissue
contamination is affected by the level of contamination of the water column, whereas, shrimp
tissue contamination is dependent on the level of contamination of sediment pore water.
Recreational Finfish Fisheries
Exposure of recreational finfish to drilling fluid contaminants occurs through the uptake of
dissolved pollutants found in the water column. The concentration of pollutants in finfish tissue is
used to calculate the risk of noncarcinogenic and carcinogenic (arsenic only) risk from ingestion of
recreationally-caught fish. In both baseline and discharge option scenarios, the hazard quotients
are several orders of magnitude less than 1, so toxic effects are not predicted to occur. Also, the
lifetime excess cancer risks for baseline and the discharge options are less than 10~6 and are,
therefore, considered by EPA acceptable for either of these scenarios.
Commercial Shrimp Fisheries
EPA based projected shrimp tissue concentrations of pollutants from SBF discharges on the
uptake of pollutants from sediment pore water. The pore water pollutant concentrations are based
on the assumption of even distribution of the total annual SBF discharge over an area of impact
surrounding the model well. Only shallow water model wells are used in this assessment due to
the limited shrimp harvesting that occurs in water depths greater than 1,000 feet. Health risks for
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ES-6
commercial shrimp were not performed for the Cook Inlet, Alaska geographic area because shrimp
are not harvested commercially hi that area.
Numerically, the hazard quotients and lifetime excess cancer risks decrease by 53 percent
under BAT discharge option 1 as compared to baseline and by 57 percent under BAT discharge
option 2. For both current technology and discharge option, the hazard quotients are several orders
of magnitude less than 1, so toxic effects are not predicted to occur under either scenario. Also,
all of the lifetime excess cancer risks for both current technology and discharge option are less
than 10~6 and are, therefore, acceptable under either scenario.
C. Toxicity
EPA has reviewed information concerning the determination of toxicity to the receiving
environment of SBFs and SBF base fluids. This information includes data generated for toxicity
requirements imposed on North Sea operators as well as experimental testing conducted by the oil
and gas industry in the United States. Because the synthetic base fluids are water insoluble and the
SBFs do not disperse in water as water-based drilling fluids (WBFs) do, but rather tend to sink to
the bottom with little dispersion, most research has focused on determining toxicity in the
sedimentary phase as opposed to the aqueous phase.
SBFs have routinely been tested using an aqueous phase test to measure toxicity of the
suspended particulate phase (SPP) (the SPP toxicity test) and found to have low toxicity.
However, recently presented data from an interlaboratory variability study indicates that the SPP
toxicity results are highly variable when applied to SBFs, with a coefficient of variation of 65.1
percent. Variability reportedly depended on such things as mixing times and the shape and size of
the SPP preparation containers.
Although there are data available on the toxicity of both SBFs and SBF base fluids from the
North Sea and United States, several assumption can be made.
(1) North Sea amphipods appear to be less sensitive to synthetic base fluids than those
amphipods currently used in US testing.
(2) When comparing SBFs and DBFs, base fluid toxicity appears to show greater discriminatory
power than does drilling fluid toxicity.
(3) Discriminatory power seems to be diminished with the use of formulated sediments.
(4) Mysid SPP testing does not seem to give meaningful results for SBFs.
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ES-7
D. Bioaccumulation
EPA reviewed several studies on the bioaccumulation potential of synthetic base fluids. The
available information is scant, comprising only a few studies on octanol:water partition
coefficients (Pow) and two on tissue uptake in experimental exposures [only one of which derived a
bioconcentration factor (BCF)]. The Pow represents the ratio of a material present in the oil phase,
i.e., in octanol versus the water phase. The Pow generally increases as a molecule becomes less
polar (more hydrocarbon-like). The available information on the bioaccumulation potential of
synthetic base fluids covers only three types of synthetics: an ester (one studies), internal olefins
(TO; three studies), and poly alpha olefins (PAO; four studies). One study included a low toxicity
mineral oil (LTMO) for comparative purposes. This limitation with respect to the types of
synthetic base fluids tested is partially mitigated by the fact that these materials represent the more
common base fluids currently in use in drilling operations. In general, the order of decreasing
bioaccumulation potential is PAO, lOs, and then esters.
Data suggest that synthetic base fluids do not pose a serious bioaccumulation potential.
. Despite this general conclusion, existing data cannot be considered sufficiently extensive to be
conclusive. This caution is specifically appropriate given the wide variety of chemical
characteristics resulting from marketing different formulations of synthetic fluids (i.e., carbon
chain length or degree of unsaturation within a fluid type, or mixtures of different fluid types).
Therefore, based on the requirements of the final rule, only internal olefins (LOs) and esters can be
discharged.
E. Biodegradation
EPA reviewed studies regarding the biodegradability of synthetic base fluids deposited on
offshore marine sediments. In addition, EPA compared the various methods used to predict SBF
biodegradation. Method variations include: calculation of biochemical oxygen demand in
inoculated freshwater aqueous media versus uninoculated seawater aqueous media; determination
of product (gases) evolved versus the concentration of synthetic base fluid remaining at periodic
test intervals; varying initial concentrations of test material; aqueous versus sediment matrices; and
within sediment matrices, layering versus mixed sediment protocols.
In the field, the mechanisms observed from the deposition of SBF contaminated drill cuttings
involve the initial smothering of the benthic community followed by organic enrichment of the
sediment due to-adherent drilling fluids. Organic enrichment causes oxygen depletion due to the
biodegradation of the discharged synthetic base fluids. This biodegradation results in
predominantly anoxic conditions in the sediment, with limited aerobic degradation processes
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ES-8 ;
occurring at the sedimentwater column interface. Therefore, the biodegradation of deposited
drilling fluid will be an anaerobic process to a large degree. Standardized tests that utilize
aqueous media, while readily available and easily performed, may not adequately mimic the
environment in which the released synthetic base fluid is likely to be found and degraded. As a
result, alternative test methods have been developed that more closely simulate seabed conditions.
The result of this review is that the current state of knowledge for these materials is as
follows:
• All synthetic fluids have high theoretical oxygen demands (ThODs) and are likely to produce
a substantial sediment oxygen demand when discharged in the amounts typical of offshore
drilling operations.
• Existing aqueous phase laboratory test protocols are incomparable and results are highly
variable. Sedimentary phase tests are less variable in their results, although experimental
differences between the "simulated seabed" and "solid phase" protocols have resulted in
variations between test results.
• There is disagreement among the scientific community as to whether slow or rapid
degradation of synthetic base fluids is preferable with respect to limiting environmental
damage and hastening recovery of benthic communities. Materials which biodegrade
quickly will deplete oxygen more rapidly than more slowly degrading materials. However,
rapid biodegradation also reduces the exposure period of aquatic organisms to materials
which may bioaccumulate or have toxic effects. EPA believes that rapid degradation is
preferable because seafloor recovery has been correlated with disappearance of the SBF
base fluid.
• Existing field data suggest these materials will be substantially degraded on a time scale of
one to a few years; however, the distribution and fate of these materials is not extensively
documented, especially as applicable to the Gulf of Mexico where only three field studies
have been conducted.
The existing data from field studies suggest that organic enrichment of the sediment is a
dominant impact of SBF-cuttings discharges. Biodegradability of these materials is an important
factor in assessing their potential environmental fate and effects. Therefore, based on the
requirements of the final rule, only internal olefins (IDs) and esters can be discharged.
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ES-9
G. Seabed Surveys
EPA reviewed and summarized seabed surveys conducted at sites where cuttings
contaminated with SBFs (SBF-cuttings) have been discharged. The reviewed seabed surveys
measured either sediment or biologic effects from discharges of either WBFs or SBFs.
Specifically, indicators of drilling fluid impact of seabed sediments are determined by measuring
drilling fluid tracer concentrations (as either barium or SBF base fluid) in the sediment at varying
distances from the drill site in an attempt to determine fluid dispersion and range of potential
impact. Another class of impacts frequently measured are benthic community effects. The purpose
of these studies is to assess potential drilling fluid affects such as increased metals and/or anoxia
on biota.
From the existing survey information, it is clear that the area of impact resulting from SBF
cuttings discharges is significantly smaller than that resulting from WBF discharges. It appears
that biological impacts from SBF cuttings discharges may range from as little as 50 m to as much
as 500 m shortly after discharges cease to as much as 200 m a year later. WBF biological impacts
have been found up to 2,000 m. Similarly, maximum sediment concentrations of SBFs have been
found at approximately 100 to 200 meters from the discharge location, whereas maximum
concentrations of indicators of WBF discharge (e.g., barium) have been found out to 35 km from
the point of discharge.
Ester SBFs appear to be more readily biodegraded in North Sea studies than an ether SBF;
the Gulf of Mexico study suggests PAOs also are less biodegradable than esters. Also, although
esters appear to be readily biodegraded, one study indicates the persistence of uncharacterized
"minor" impacts on benthos after synthetic-based fluid levels have fallen to reference levels.
These limited data, however, are not optimal as a basis for any reliable projections concerning the
potential nature and extent of impacts from discharges of SBFs. However, the reported adverse
benthic community impacts are expected, given the basic SBF and marine sediment chemistry, the
level of nutrient enrichment from these materials, and the ensuing development of benthic anoxia.
The extent and duration of these impacts are much more speculative. Severe effects seem likely
within 200 m of the discharge; impacts as far as 500 m have been demonstrated. The initiation of
benthic recovery seems likely within a year, although it also seems unlikely that it will be
complete within one year.
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1-1
1. INTRODUCTION
This document presents the analyses and results of the environmental assessment for the final
rule for synthetic-based drilling fluids (SBFs) and other non-aqueous drilling fluid wastestreams,
and cuttings contaminated with these drilling fluids. The environmental assessment consists of an
evaluation of the ecological and indirect human health impacts for each proposed regulatory option
with respect to discharges to water. This document describes the environmental characteristics of
SBF drilling wastes (e.g., toxicity, bioaccumulation, biodegradation), the types of anticipated
impacts, and the pollutant modeling results for water column concentrations, pore water
concentrations, and human health effects via consumption of affected seafood. This document does
not consider the potential non-water quality environmental effects associated with the final rule.
Since about 1990, the oil and gas extraction industry has developed many new oleaginous
(oil-like) base materials from which to formulate high performance drilling fluids. A general class
of these are called "synthetic" materials. This class of substances include vegetable esters, poly
alpha olefins, internal olefins, linear alpha olefins, synthetic paraffins, ethers, linear alkyl
benzenes, and others. Other, nonsynthetic oleaginous materials have also been developed for this
purpose, such as the enhanced mineral oils and non-synthetic paraffins. Industry developed these
synthetic and non-synthetic oleaginous materials as the base fluid to provide the drilling
performance characteristics of traditional oil-based fluids (OBFs) based on diesel and mineral oil,
but with lower environmental impact and greater worker safety. These environmental and safety
characteristics have been achieved through lower toxicity, elimination of polynuclear aromatic
hydrocarbons (PAHs), faster biodegradability, and lower bioaccumulation potential. Another
benefit to SBF use is increased drilling efficiency. SBFs enable drilling to occur at a faster rate
with less washout (i.e., borehole sloughing) than water based fluids (WBFs). Due to these
characteristics, some drilling projects have replaced WBFs with SBFs. In this document, the
synthetic or other new oleaginous base fluids will be referred to collectively as synthetic base
fluids. The drilling fluids formulated from them will be referred to collectively as SBFs.
In the relatively new area of ultra-deep water drilling (i.e., water depths greater than 3,000
feet), new drilling methods are evolving which can significantly improve drilling efficiencies and
thereby reduce non-water quality environmental impacts (e.g., fuel, steel casing consumption, air
emissions) and the per well amount of pollutants discharged. Subsea drilling fluid boosting,
referred to as "dual gradient drilling," is one such new drilling technology.
As SBFs came into commercial use, EPA determined that the current drilling discharge
monitoring methods, which were developed to control the discharge of water-based fluids
(WBFs), did not appropriately control the discharge of these new drilling fluids. Because WBFs
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1-2
disperse in water, oil contamination of WBFs with formation oil or other sources can be measured
by the static sheen test. Many soluble or water-accommodated toxic components of the WBFs will
disperse in the aqueous phase and be detected by the suspended particulate phase (SPP) toxicity
test. With SBFs, which are highly hydrophobic and do not disperse in water but instead sink as a
mass, formation oil contamination has been shown to be less detectable by the static sheen test.
Similarly, the potential toxicity of the discharge to the benthos is not apparent in the current SPP
toxicity test.
EPA has, therefore, sought to identify methods to control the discharge of cuttings associated
with SBFs (SBF-cuttings) in a way that reflects the appropriate level of technology. One way to
do this is through stock limitations on the base fluids from which the drilling fluids are formulated.
This would ensure that the substitution of synthetic and other oleaginous base fluids for traditional
mineral and diesel oils reflects the appropriate level of technology. In other words, EPA wants to
ensure that only the SBFs formulated from the "best" base fluids are allowed for discharge.
Parameters that distinguish the various base fluids are the polynuclear aromatic hydrocarbon
(PAH) content, sediment toxicity, rate of biodegradation, and potential for bioaccumulation.
EPA also determined that the SBF-cuttings should be controlled with other limitations, such
as a limitation on the toxicity of the SBF at the point of discharge and a limitation on the mass or
concentration of SBFs discharged with the drill cuttings. The latter type of limitation would take
advantage of the solids separation efficiencies achievable with SBFs, and consequently minimize
the discharge of organic and toxic components.
In addition to the discharge option described above, EPA is also considering a zero
discharge option for SBF-cuttings. Under the zero discharge option, SBF-cuttings would either be
injected at the well site or hauled by supply boats to shore for onshore injection or for disposal at
a land-based facility.
EPA has determined the water quality and human health impacts of current industry practice
and each of the three regulatory options (i.e., two controlled discharge options and zero discharge)
based on changes in the discharge of SBF wastes, and on the number of wells projected to use
SBFs. Under the discharge option, wells drilled using SBFs will be allowed to discharge SBF-
cuttings. Due to the proposed limitations, less SBF would be retained on the cuttings and so less
SBF would be discharged per well than is currently practiced in the Gulf of Mexico. In addition,
under the discharge option, EPA will control the toxicity, PAH content, and biodegradation rate of
the base fluids used in SBFs. For wells currently using OBFs for drilling, EPA projects that under
the discharge options, a portion of these wells will convert to SBF usage and will discharge SBF-
cuttings. These wells comprise a fraction of the OBF wells drilled in the Gulf of Mexico and all
of the OBF wells drilled in offshore California and Cook Inlet, Alaska.
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1-3
The effect of the zero discharge option would be to eliminate the discharge of SBF-cuttings
into ambient waters by those wells currently drilled with SBFs. However, EPA believes another
effect of zero discharge would be that many of the wells currently using SBFs would convert to
either DBFs or WBFs. EPA has determined that use of OBFs in place of SBFs would lead to an
increase in NWQIs including the toxicity of the drilling waste. Use of WBFs in place of SBFs
would generally lead to a per well increase pollutants discharged, an increase in NWQIs, and an
increase in WBF aquatic toxicity. EPA estimates that, under the zero discharge option, some
operators will switch to WBF with more NAF-properties (e.g., lubricity, shale suppression) and
that these WBFs tend to exhibit greater aquatic toxicity than traditional WBFs.
Nonetheless, while SBF-cuttings discharge with adequate controls is preferred over zero
discharge in U.S. Offshore waters, SBF-cuttings discharge with inadequate controls is not
preferred over zero discharge. EPA believes that to allow discharge of SBF-cuttings in U.S.
Offshore waters, there must be appropriate controls to ensure that EPA's discharge limitations
reflect the "best available technology" or other appropriate level of technology. EPA has worked
with industry to address the appropriate determination of PAH content, sediment toxicity,
biodegradation, bioaccumulation, the quantity of SBF discharged, and formation oil contamination.
This environmental assessment presents background information and several types of
characterizations and assessments concerning the discharge of SBFs and SBF-cuttings, including:
A description of the regulatory options considered for the final rule (Chapter 2).
A characterization of the industry, including the geographic areas and the population affected
by the final rule (Chapter 3).
Wastestream characterizations in terms of SBFs and SBF-cuttings (Chapter 3).
Characterization of the affected environment, including the receiving water and fisheries
(Chapter 3).
Water quality compliance assessments for SBF-cuttings discharges to receiving waters and
comparison of receiving water pollutant concentrations (water column and interstitial (pore)
water) projected from surface water dispersion modeling to Federal numeric water quality
standards (Chapter 4).
A carcinogenic and non-carcinogenic risk assessment for SBF-cuttings for high-rate seafood
consumption, based on seafood contamination levels projected from modeling (Chapter 5).
A summary and comparison of the aquatic toxicity test results conducted to date on SBFs
(Chapter 6).
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1-4
• A summary and comparison of bioaccumulation study results conducted to date on SBFs
(Chapter 7).
A summary and comparison of biodegradation study results conducted to date on SBFs
(Chapter 8).
• A summary and comparison of seabed survey results conducted to date on SBF discharges to
assess benthic impacts (Chapter 9).
The pollutant concentrations in water and seafood tissue are based solely on analysis of
discharges from this one particular wastestream under different regulatory options. That is, the
analyses do not consider background pollutant concentrations or pollutant loadings from other
potential discharges.
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2-1
2. DESCRIPTION OF REGULATORY OPTIONS
This environmental assessment determines impacts for the discharge of wastes associated
with synthetic-based drilling fluids (SBFs) under current industry practice and three regulatory
options considered by EPA for the SBF rule: two controlled discharge options and a zero
discharge option.
In the February 1999 Proposal, EPA discussed two BAT options for SBFs associated with
drill cuttings, "SBF-cuttings": (1) a controlled discharge option (based on two SBF-cuttings
discharges from solids control equipment); and (2) a zero discharge option. EPA's preferred
options was the controlled discharge option in the February 1999 proposal. Through discussions
with stakeholders and the October 1999 site visits to offshore drilling operations, EPA obtained
more information about current and emerging solids control practices. Consequently, in the April
2000 NODA (65 FR 21560) EPA revised and added one new BAT controlled discharge option
for SBF-cuttings. The additional BAT SBF-cuttings controlled discharge option is based on only
one discharge from the cuttings dryer (e.g., vertical or horizontal centrifuge, squeeze press mud
recovery unit, High-G linear shaker) and zero discharge of fines from the fines removal unit (e.g.,
decanting centrifuge, mud cleaner). The additional BAT SBF-cuttings discharge option is
equivalent in all respects to the February 1999 Proposal controlled discharge option except for the
zero discharge of fines. Therefore, the range of regulatory options considered for SBF-cuttings
under BAT limitations included:
(1) a controlled discharge option (based on SBF-cuttings discharges from the cuttings
dryer and fines removal unit);
(2) a controlled discharge option (based on SBF-cuttings discharges from the cuttings
dryer only); and
(3) a zero discharge option.
The discharge options control under BAT the stock base fluid through limitations on PAH
content, sediment toxicity, and biodegradation rate. Moreover, both discharge options control
under existing BPT and BCT limitations sheen formation at the point of discharge and control
under BAT formation oil content, sediment toxicity, and quantity of SBF base fluid discharged at
the point of discharge. EPA is retaining the existing BAT limitations on: (1) the stock barite of 1
mg/kg mercury and 3 mg/kg cadmium; (2) the maximum aqueous toxicity of discharged SBF-
cuttings as the minimum 96-hour LC50 of the SPP shall be 3 percent by volume; and (3) prohibiting
the discharge of drilling wastes containing diesel oil in any amount. These limitations control the
levels of toxic metal and aromatic pollutants respectively. EPA at this time thinks that all of these
components are essential for appropriate control of SBF-cuttings discharges.
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2-2
EPA used stock limitation and discharge limitations in a two part approach to control SBF-
cuttings discharges under BAT. The first part is the control of which SBF are allowed for
discharge through use of stock limitations (e.g., sediment toxicity, biodegradation, PAH content,
metals content) and discharge limitations (e.g., diesel oil prohibition, formation oil prohibition,
sediment toxicity, aqueous toxicity). The second part is the control of the quantity of SBF
discharged with SBF-cuttings. As previously stated in the April 2000 NODA, EPA finds that this
control is particularly important because limiting the amount of SBF content in discharged cuttings
controls: (1) the amount of SBF discharged to the ocean; (2) the biodegradation rate of discharged
SBF; and (3) the potential for SBF-cuttings to develop cuttings piles and mats which are
detrimental to the benthic environment.
While discharge of SBF-cuttings would be allowed under the discharge options, discharge
of SBFs not associated with drill cuttings would not be allowed. Since zero discharge of neat
SBFs is current industry practice due to the value of the SBFs recovered, this option has no
incremental environmental impact. For this portion of the wastestream, therefore, an
environmental assessment was not conducted.
Under the zero discharge option, neat SBFs (not associated with drill cuttings) as well as
SBF-cuttings would be prohibited from discharge. Because the zero discharge option results in the
absence of discharged pollutants, the environmental assessment analyses did not require
calculations to demonstrate zero environmental impacts.
EPA determined that the only major effect that the discharge options would have on the
characterization of the SBF-cuttings currently discharged would be to reduce the retention of the
SBF on the cuttings from the current 10.2% base fluid to 4.03% or 3.82% base fluid under each of
the discharge options. This means that for the purpose of this environmental assessment, base fluid
selection, formation oil contaminant level, and sheen forming characteristics would not be
materially affected in moving from current practice to the discharge option.
The different SBF retention values, 10.2% for current technology and 4.03% and 3,82% for
the discharge options, represent different amounts of SBF discharged into the receiving water. For
the water quality analyses (Chapter 4) and the human health impact assessments (Chapter 5), the
impacts under the discharge options (4.03% and 3.82% retentions) and under current technology
(10.2% retention) were determined.
Also, EPA projects that the discharge option would encourage operators to convert wells
currently drilled with oil-based drilling fluid (OBF) and water-based drilling fluid (WBF) to SBF.
Thus, EPA projects that in the Gulf of Mexico, while 221 wells annually are currently projected to
drill with SBF, after the rule an additional 58 wells (30 converting from OBF and 28 converting
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. . 2-3
from WBF), for a total of 279 would drill with SBF. Therefore, the analyses of this environmental
assessment assume that in the Gulf of Mexico, the current practice is 221 wells discharging at
10.2% base fluid retention on cuttings and the discharge option would consist of 279 wells drilled
annually and discharging cuttings at 3.82% retention.
In offshore California and Cook Inlet, Alaska, no SBF wells are currently drilled. If
facilities in Cook Inlet can demonstrate to the permitting authority that they can not zero discharge
their drilling waste, the may be considered for a permit allowing discharge of SBF cuttings.
Therefore, this environmental assessment models the impact of discharges from one shallow water
development well under the discharge options. According to industry, no wells are projected to be
drilled using SBFs in California even under a discharge scenario. However, should industry
practices change so that SBFs would be used, EPA has modeled impacts resulting from drilling
one shallow water and 11 deep water development wells in offshore California.
Current regulations establish the geographic areas where drilling wastes may be discharged:
offshore subcategory waters beyond 3 miles from the shoreline and, in Alaska, offshore waters
with no 3-mile restriction. The SBF effluent guidelines would be applicable only where drilling
wastes are currently allowed for discharge. The only coastal subcategory waters where drilling
wastes may be discharged is in Cook Inlet, Alaska. In total, there are three areas where current
guidelines allow drilling wastes to be discharged and drilling is active: offshore Gulf of Mexico,
offshore California, and Cook Inlet, Alaska. Because these are the only geographic areas where
EPA projects pollutant loadings to change as a result of the proposed rule, they are the only areas
considered in the environmental assessment.
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3-1
3. CHARACTERIZATION
3.1 Industry Characterization
The geographic areas where drilling wastes are allowed to be discharged are: the offshore
subcategory waters of the Atlantic, Gulf of Mexico, and Pacific coasts beyond 3 miles from shore;
all of the offshore subcategory waters of Alaska, which has no 3 mile discharge restriction; and the
coastal subcategory waters of Cook Inlet, Alaska. Within these discharge areas, drilling is
currently active in three places: (i) the Gulf of Mexico (GOM), (ii) offshore southern California;
and (iii) Cook Inlet, Alaska. Offshore subcategory waters of Alaska has active drilling and
effluent guidelines allows discharge. However, drilling wastes are not currently discharged in the
Alaska offshore waters.
Among these three areas, the vast majority of drilling activity occurs in the GOM, where
1,302 wells were drilled in 1997. This activity compares to 28 wells drilled in California and 7
wells drilled in Cook Inlet in 1997. In the GOM, over the last few years, there has been a high
growth in the number of wells drilled in the deepwater, defined by the Minerals Management
Service (MMS) as water greater than 1,000 feet deep. For example, in 1995, 84 wells were
drilled hi the deepwater, comprising 8.6 percent of all GOM wells drilled that year. By 1997, that
number increased to 173 wells drilled and comprised over 13 percent of all GOM wells drilled.
Most recent 1999 data show that this trend is continuing as over 15% of all GOM wells drilled
were in deep water. This increased activity in deepwater increases the usefulness of SBFs.
Operators drilling in deepwater cite the potential for riser disconnect in floating drill ships, which
favors SBF over OBF; higher daily drilling cost that more easily justifies use of more expensive
SBFs over WBFs; and the greater distance to barge drilling wastes that may not be discharged
(i.e.,OBFs). r
In the relatively new area of ultra-deep water drilling (i.e., water depths greater than 3,000
feet), new drilling methods are evolving which can significantly improve drilling efficiencies and
thereby reduce NWQIs (e.g., fuel, steel casing consumption, air emissions) and the per well
amount of pollutants discharged. Subsea drilling fluid boosting, referred to as "dual gradient
drilling," is one such new drilling technology. Dual gradient drilling is similar to traditional rotary
drilling methods as previously described with the exception that the drilling fluid is energized or
boosted by use of a pump at or near the seafloor. By boosting the drilling fluid, the adverse effect
on the wellbore caused by the drilling fluid pressure from the seafloor to the surface is eliminated,
thereby allowing wells to be drilled with as much as a 50% reduction in the number of casing
strings generally required to line the well wall. As a result of the reduced number of casing strings,
dual gradient wells can be drilled almost one-third faster and with smaller hole sizes than
conventional deep water drilling. Smaller hole sizes and faster drilling translate into fewer
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3-2 __
pollutants being discharged to the ocean and fewer NWQI. Dual gradient drilling technology can
also potentially eliminate or reduce the amount of whole drilling fluid released to the environment
during an inadvertent riser disconnect. Finally, dual gradient drilling technology can greatly reduce
the potential release of drilling fluid when drilling through shallow sand intervals (e.g., shallow
water flow) (Docket No. W-98-26, Record No. IV.B.a.6).
Some dual gradient drilling systems require the separation of the largest cuttings (e.g., larger
than approximately 1A inch) at the seafloor since these cuttings may interfere with the rotatory
action of subsea pumps (e.g., electrical submersible pumps). The larger cuttings are routed at the
seafloor to a venturi action pump (with no moving parts), mixed with seawater, and pumped to a
cuttings discharge hose at the seafloor within a 300 foot radius of the well site. The hose is
perforated on the last 50 ft of its length to maximize the spread of cuttings. The action of pumping
cuttings with seawater can be expected to have some cleaning and dispersion effect. A remotely
operated vehicle (ROV) can also be used to reposition the subsea discharge hose to maximize
cuttings dispersal. Representative samples of drill cuttings discharged at the seafloor can be
transported to the.surface by a ROV for purposes of monitoring. The drilling fluid, which is
boosted at the seafloor and transports most of the drill cuttings (e.g., 95-98% of total cuttings
generated) back to the surface, is processed as described in the general rotary drilling methods
described in the Development Document.
EPA has adopted the MMS categorization of drilling wells according to type of drilling
operation, i.e., exploratory (E) or development (D), and water depth. Deep water (DW) wells are
wells that are drilled in water depths greater than 1,000 feet whereas shallow water (SW) wells
are drilled in water less than 1,000 feet. Using information gathered from industry, EPA projected
the number of wells drilled annually using SBFs, WBFs, and OBFs (EPA, 2000). Table 3-1
presents a summary of the wells drilled with OBFs, SBFs, and WBFs as used in the analyses for
the environmental assessment. For the water quality and human health impact analyses, EPA
projected that under the discharge options, certain wells currently using OBFs as well as WBFs
would switch to SBF usage (EPA, 2000). In the Gulf of Mexico, EPA projected that 40% of the
wells drilled with OBF, all of which are located in shallow water, would convert to SBF. In
addition, EPA projected that 6% of shallow water wells and 8% of deep water wells drilled with
WBFs will convert to SBF under the discharge options. In Cook Inlet, Alaska, EPA projected that
only one shallow water development OBF well would convert to SBF. Based on information
provided by industry after publication of the NODA, wells drilled in offshore California are not
projected to be drilled with SBFs under any of the regulatory options.
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3-3
Exhibit 3-1. Estimated Number of Wells Drilled Annually By Drilling Fluid
»!£%. *^-
Well Type
SWD *SWE
" DWD
DWE
Total
Wells
BASELINE
WBF
SBF
OBF
WBF
SBF
OBF
WBF
SBF
OBF
Gulf of
Mexico
Offshore
California
Cook Inlet,
Alaska
538
91
44
3
0
1
3
0
1
298
51
25
2
0
1
1
0
1
23
31
0
0
0
0
0
0
0
36
48
0
0
0
0
0
0
0
895
221
69
5
0
2
4
0
2
BAT Options land 2
WBF
SBF
OBF
WBF
SBF
OBF
WBF
SBF
OBF
Gulf of
Mexico
Offshore
California
Cook Inlet,
Alaska
504
132
26
3
0
1
3
1
0
279
74
15
2
0
1
1
0
1
21
33
0
0
0
0
0
0
0
34
49
0
0
0
0
0
0
0
838
279
41
5
0
2
4
1
1
BAT Option 3
WBF
SBF
OBF
WBF
SBF
OBF
WBF
SBF
OBF
Gulf of
Mexico
Offshore
California
Cook Inlet,
Alaska
538
0
135
3
0
1
3
0
1
298
0
76
2
0
1
1
0
1
32
6
16
0
0
0
0
0
0
51
11
40
0
0
0
0
0
0
919
14
252
5
0
. 2
4
0
2
(a)
While this table lists total number of wells, the only wells included in the analysis are those affected by
this rule: SBF wells or wells converting from OBF or WBF to SBF in the discharge options or converting
from SBF to OBF or WBF in the zero discharge option.
EPA assumes that 95 percent of GOM shallow water development wells of this analysis are existing
sources, and 5 percent are new sources (equals 34 new source wells).
EPA assumes that 50 percent of GOM deep water development wells of this analysis are existing sources,
and 50 percent are new sources (equals 26 new source wells).
EPA assumes all offshore California and Cook Inlet, Alaska, wells are existing sources. For Cook Inlet,
the SWD OBF well will convert to an SBF well under the discharge options.
Source: EPA, 2000.
(b)
(c)
(d)
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3-4
3.2 Wastestream Characterization
The American Petroleum Institute (API) provided EPA with characteristic well data in terms
of well diameters and well section depths for model wells. From this, EPA calculated the
volumes of waste generated (EPA, 1999). As in the MMS data, API information distinguishes
wells into four categories: shallow waterdevelopment, shallow water exploratory, deep water
development, and deep water exploratory.
Drill cuttings are produced continuously at the bottom of the hole at a rate proportionate to
the advancement of the drill bit. These drill cuttings are carried to the surface by the drilling fluid,
where the cuttings are separated from the drilling fluid by the solids control system. The drilling
fluid is then sent back down hole, provided it still has characteristics to meet technical
requirements. Various sizes of drill cuttings are separated by the solids separations equipment. It
is necessary to remove both the fines (small sized cuttings) and the large sand- and gravel-sized
cuttings from the drilling fluid stream to maintain the required flow properties.
Because of cost, SBFs, used or unused, are considered a valuable commodity by the industry
and not a waste. It is industry practice to continuously reuse the SBF while drilling a well
interval, and at the end of the well, to ship the remaining SBF back to shore for refurbishment and
reuse. Compared to WBFs, SBFs are relatively easy to separate from the drill cuttings because the
drill cuttings do not disperse in the drilling fluid to the same extent. With WBF, due to dispersion
of the drill cuttings, drilling fluid components often need to be added to maintain the required
drilling fluid properties. These additions are often in excess of what the drilling system can
accommodate. The excess "dilution volume" of WBF is discharged. This excess dilution volume
does not occur with SBF. For these reasons, SBF is only discharged as a contaminant of the drill
cuttings wastestream. It is not discharged as neat drilling fluid (drilling fluid not associated with
cuttings).
The top of the well is normally drilled with a WBF. As the well becomes deeper, the
performance requirements of the drilling" fluid increase, and the operator may, at some point,
decide that the drilling fluid system shouldi>e changed to either a traditional OBF using diesel oil
or mineral oil, or an SBF. The system, including the drill string and the solids separation
equipment, must be changed entirely from"the WBF to the SBF (or OBF) system, because the two
drilling fluid systems do not function as:ajblended system. Thus, the entire system is either a water
dispersible drilling fluid or a water non-dispersible drilling fluid (such as an SBF). The decision
to change the system from a WBF water dispersible system to an OBF or SBF water non-
dispersible system depends on many factors including:
• the operational considerations, i.e. rig type (risk of riser disconnects with
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__^_____ 3-5
floating drilling rigs), rig equipment, distance from support facilities,
• the relative drilling performance of one type fluid compared to another, e.g., rate of
penetration, well angle, hole size/casing program options, horizontal deviation,
• the presence of geologic conditions that favor a particular fluid type or performance
characteristic, e.g., formation stability/sensitivity, formation pore pressure vs. fracture
gradient, potential for gas hydrate formation,
• drilling fluid cost - base cost plus daily operating cost,
• drilling operation cost - rig cost plus logistic and operation support, and
• drilling waste disposal cost.
Industry has commented that while the right combination of factors that favor the use of SBF can
occur in any area, they most frequently occur with "deep water" operations. This is due to the fact
that these operations are higher cost and can therefore better justify the higher initial cost of SBF
use. Recently, SBF use has become not only limited to difficult drilling conditions within a well
interval, but is also used in drilling the entire well because of the more efficient drilling SBFs
provide compared to WBFs. SBFs decrease washout and increase the speed of drilling thereby
decreasing the total amount of waste generated during drilling.
The volume of cuttings generated while drilling the SBF intervals of a well depends on the
type of well (development or production) and the water depth. According to analyses of the model
wells provided by industry representatives, wells drilled in less than 1,000 feet of water are
estimated to generate 565 barrels of cuttings for a development well and 1,184 barrels of cuttings
for an exploratory well. Wells drilled in water greater than 1,000 feet deep are estimated to
generate 855 barrels of cuttings for a development well, and 1,901 cuttings for an exploratory well
(see Exhibit 3-2). These values assume 7.5 percent washout, based on the rule of thumb reported
by industry representatives of 5 to 10 percent washout when drilling with. SBF. Washout is caving
in or shifting off of the well bore. Washout, therefore, increases hole volume and increases the
amount of cuttings generated when drilling a well. Assuming no washout, the values above
become, respectively, 526, 1,101, 795, and 1,768, barrels of dry cuttings.
The drill cuttings range in size from large particles on the order of a centimeter in size to
small particles a fraction of a millimeter in size, called fines. As the drilling fluid returns from
downhole laden with drill cuttings, it normally is first passed through primary shale shakers which
remove the largest cuttings, ranging in size of approximately 1 to 5 millimeters. The drilling fluid
may then be passed over secondary shale shakers to remove smaller drill cuttings. Finally, a
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3-6
Exhibit 3-2. Volume of SBF-Cuttings Generated Per Model Well
Parameter
Calculated SBF Interval Volume (bbls)
SBF Interval Volume Plus
7.5% Washout (bbls)
Amount of Dry Cuttings Generated
Per Interval Volume (Ibs)
Shallow Water
(<1,000 ft)
Development
526
565
514,150
Exploratory
1,101
1,184
1,077,440
Deep Water
(2:1,000 ft)
Development
795
855
778,050
Exploratory
1,768
1,901
1,729,910
Source: EPA, 2000
portion or all of the drilling fluid may be passed through a centrifuge or other shale shaker with a
very fine mesh screen, for the purpose of removing the fines. It is important to remove fines from
the drilling fluid in order to maintain the desired flow properties of the active drilling fluid system.
Thus, the cuttings wastestream usually consists of larger cuttings from a primary shale shaker,
smaller cuttings from a secondary shale shaker, and fines from a fine mesh shaker or centrifuge.
Before being discharged, the larger cuttings are sometimes sent through an additional
separation device in order to recover additional drilling fluid.
The recovery of SBF from the cuttings serves two purposes. The first is to deliver drilling
fluid for reintroduction to the active drilling fluid system and the second is to minimize the
discharge of SBF. The recovery of drilling fluid from the cuttings is a conflicting concern, because
as more aggressive methods are used to recover the drilling fluid from the cuttings, the cuttings
tend to break down and become fines. The fines are more difficult to separate from the drilling
fluid (an adverse affect for pollution control purposes), but in addition they deteriorate the
properties of the drilling fluid. Increased recovery from cuttings is more of a problem for WBF
than SBF because in WBFs the cuttings disperse more and spoil the drilling fluid properties.
Therefore, compared to WBF, more aggressive methods of recovering SBF from the cuttings
wastestream are practical. These more aggressive methods may be justified for cuttings
associated with SBF so as to reduce the discharge of SBF. This, consequently, will reduce the
quantity of toxic organic and metallic components of the drilling fluid discharged.
Drill cuttings are typically discharged continuously during drilling, as they are separated
from the drilling fluid in the solids separation equipment. The drill cuttings will also carry a
residual amount of adherent drilling fluid. Total suspended solids (TSS) makes up the bulk of the
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3-7
pollutant loadings, and is comprised of two components: the drill cuttings themselves, and the
solids in the adhered drilling fluid (see Exhibit 3-3). The drill cuttings are primarily small bits of
stone, clay, shale, and sand. The source of the solids in the drilling fluid is primarily the barite
weighting agent, and clays that are added to modify the viscosity. Because the quantity of TSS is
so high and consists of mainly large particles that settle quickly, discharge of SBF drill cuttings
can cause benthic smothering and/or sediment grain size alteration resulting in potential damage to
invertebrate populations and benthic community structure.
Additionally, environmental impacts can be caused by toxic, conventional, and
nonconventional pollutants adhering to the solids. The adhered SBF drilling fluid is mainly
composed, on a volumetric basis, of the synthetic material, or more broadly speaking, oleaginous
material. The oleaginous material may be toxic or bioaccumulate, and it may contain priority
pollutants such as polynuclear aromatic hydrocarbons (PAHs). This oleaginous material may
cause hypoxia (reduction in oxygen) or anoxia in the immediate sediment, depending on bottom
currents, temperature, and rate of biodegradation. Oleaginous materials which biodegrade quickly
will deplete oxygen more rapidly than more slowly degrading materials. EPA, however, believes
that rapid biodegradation is environmentally preferable to persistence despite the increased risk of
anoxia which accompanies fast biodegradation. This is because recolonization of the area
impacted by the discharge of SBF-cuttings or OBF-cuttings has been correlated with the
disappearance of the base fluid in the sediment, and does not seem to be correlated with anoxic
effects that may result while the base fluid is disappearing. In studies conducted in the North Sea,
base fluids that biodegrade faster have been found to disappear more quickly, and recolonization
at these sites has been more rapid (Daan et al., 1996 and Schaanning, 1995).
As a component of the drilling fluid, the barite weighting agent is also discharged as a
contaminant of the drill cuttings. Barite is a mineral principally composed of barium sulfate, and it
is known to generally have trace contaminants of several toxic heavy metals such as mercury,
cadmium, arsenic, chromium, copper, lead, nickel, and zinc. EPA developed a profile of metals
concentrations in drilling fluids formulated with barite as part of the Offshore Effluent Limitations
Guidelines rulemaking effort. As a result of the Offshore Effluent Limitations Guidelines, stock
barite must meet the maximum limitations of cadmium of 3 mg/1 and for mercury of 1 mg/1. Exhibit
3-4 lists the concentrations of the pollutants associated with barite.
Formation oil is another contaminant of drilling fluids. Together with the synthetic oil,
formation oil contributes to the total oil concentration found in drilling fluids. EPA estimates that
a model SBF wastestream will contain 0.2% by volume formation oil (EPA, 2000). EPA obtained
the concentrations for both priority and non-conventional organic pollutants from analytical data
presented in the Offshore Subcategory Oil and Gas Development Document for Gulf of Mexico
-------
3-8
Exhibit 3-3. Model Well Characteristics
Parameter
Amount of Cuttings (Ibs)
(= TSS associated with drill cuttings)
Amount of Solids as Barite (Ibs)
(=TSS associated with drilling fluid)
@ 10.2 retention (BPT baseline)
@4.03 retention (BAT Option 1)
@3.82 retention (BAT Option 2)
Amount of Synthetic Base Fluid
Associated with Adhering Drilling
Fluid (Ibs)
@10.2 retention (BPT baseline)
@4.03 retention (BAT Option 1)
@3.82 retention (BAT Option 2)
Amount of Crude at 0.2% (vol.)
Contamination (Ibs)
@10.2 retention (BPT baseline)
@4.03 retention (BAT Option 1)
@3.82 retention (BAT Option 2)
Shallow Water
(<1,000 ft)
Development
514,150
47,028
15,913
14,631
66,979
22,664
20,838
207
70
64
Exploratory
1,077,440
98,551
33,346
30,660
140,360
47,493
43,668
433
147
135
Deep Water
(s 1,000 ft)
Development
778,050
71,166
24,080
22,141
101,358
34,296
31,534
313
106
97
Exploratory
1,729,910
158,230
53,540
49,227
225,358
76,254
70,112
696
235
217
Source:
EPA, 2000
diesel (EPA, 1993). Thus, EPA used diesel oil as an estimate for formation oil in terms of
pollutant content. Exhibit 3-5 lists the concentrations of organic pollutants found in SBF drilling
fluid contaminated with formation oil.
3.3 Receiving Water Characterization
3.3.1 Gulf of Mexico
The Gulf of Mexico is a semi-enclosed sea that can be subdivided into four physiographic
regions: the continental shelf, the continental slope and associated canyons, the Yucatan Strait, and
the Straits of Florida. Physical oceanography is dominated by the clockwise flow of the Loop
Current that enters the Gulf through the Yucatan Strait and exits through the Straits of Florida. The
average position of the northern part of the Loop Current is close to 26°N and the mean eastern
side of the Loop Current is west of the 2000 m isobath offshore Florida (MMS,1989). The most
northerly position occurs on the slope just south of Mobile, Alabama. The Loop sheds
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3-9
Exhibit 3-4. Heavy Metal Concentrations in Barite
Pollutant
Average Concentration of
Pollutants in Barite
(mg/kg)
Priority Pollutants, Metals
Cadmium
Mercury
Antimony
Arsenic
Beryllium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
1.1
0.1
5.7
7.1
0.7
240.0
18.7
35.1
13.5
1.1
0.7
1.2
200.5
Reference
Offshore Development
Document, Table XI-6
(EPA, 1993)
Non-Conventional Metals
Aluminum
Barium
Iron
Tin
Titanium
9,069.9
120,000
15,344.3
14.6
87.5
Offshore Development
Document, Table IX-6,
except barium, which was
estimated (EPA, 1993)
large eddies (diameters of 300 to 400 km, averaging 234 km) that last for periods ranging from 4
to 12 months (MMS, 1989; 1991). The vertical extent of these eddies ranges to over 1,000 m.
Surface temperatures are nearly isothermal during summer (29°-30°C)5 but show strong,
horizontal temperature gradients in winter ranging from 25°C at the core of the Loop current to 14-
15°C over the northern coastal areas. Salinities range from a low of 20 ppt during periods of high
freshwater inflow from the Mississippi River to a high of 29-32 ppt during periods of low
freshwater inflow. The thermocline also migrates due to seasonal influences. The thermocline
depth is approximately 45 m during summer and ranges from between 30 m to 60 m during winter.
Current speeds reported at a depth of 100 m from a mooring buoy located at the 1000 m
isobath off Louisiana averaged 13.4 cm/s for a period of November to September (MMS, 1989).
MMS (1988) reports an average current speed of 17.2 cm/s for December to April at a depth of
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3-10
Exhibit 3-5. Formation Oil Characteristics
Pollutant
Priority Pollutant Organics
Naphthalene
Fluorene
Phenanthrene
Phenol (ug/g)
Non-Conventional Pollutants
Alkylated benzenes
Alkylated naphthalenes
Alkylated fluorenes
Alkylated phenanthrenes
Alkylated phenols Qig/g)
Total biphenyls
Total dibenzothiopheries (ug/g)
Average Concentration
of Pollutants in SBF Contaminated
with Formation Oil
mg pollutant/
ml formation oil
'l.43
0.78
1.85
6
8.05
75.68
9.11
11.51
52.9
14.96
760
Ibs/bblofSBF
(a)
0.0010052
0.0005483
0.0013004
7.22E-08
0.0056587
0.0531987
0.0064038
0.0080909
0.0000006
0.0105160
0.0000092
Reference
Ibs/bbl pollutant cone.
calculated from Offshore
Dev. Doc., Table VII-9
(EPA, 1993)
,
(a) Assumes 0.2% contamination from formation oil using diesel as an estimate of pollutant content.
35 m in about 400 m water depth near Green Canyon off Louisiana. MMS (1988) also reports an
average current speed of 13.6 cm/s at 55 m depth in 100 m water depth (near West Flower Garden
Bank, south of Louisiana/Texas border) and an average of 19.8 cm/s at 63 m depth in 280 m water
depth (East Breaks vicinity, south of Galveston, Texas) .
Most drilling activity in the Gulf of Mexico occurs in the Central and Western planning areas
for MMS, generally offshore Louisiana and Texas.
33.2 Cook Inlet,'Alaska
Cook Inlet is located on the northwest edge of the Gulf of Alaska in southcentral Alaska. It
is a large tidal estuary that is approximately 330 km long increasing in width from 36 km in the
north to 83 km in the south. The upper inlet has water depths of 30 m to 60 m and has extensive
tidal marshes and mud flats along the western and northern margins. At the East and West
Forelands, where the upper inlet is divided from the lower inlet, water depths increase to over
130 m in deeper channels. In Lower Cook Inlet water depths range from 30 m to 40 m below the
forelands to over 180 m at the entrance to the inlet.
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• : V" 3-11
The ckculation pattern of Lower Cook Inlet is a complex pattern influenced by large tidal
ranges, bathymetry, surface wind patterns, Coriolis effect, water density structure, and shoreline
configuration. Surface circulation in the lower inlet appears to follow a generally counter-
clockwise pattern near the mouth of the inlet as clear oceanic waters are met by more turbid water
•flowing south through the inlet (Dames & Moore, 1978).
Cook Inlet currents are dominated by tidal currents and large-scale, local or regional
meterological events (EPA Region 10, 1984). Tidal currents range from 10 to 50 cm/sec. Above
the tidal currents, the Kenai Current and western surface outflows affect Cook Inlet circulation.
Houghton et al., 1981 measured flood tides ranging from 77 cm/sec to 51 cm/sec for depths
ranging from 14 m to 52 m and ebb tide ranging from 103 cm/sec to 41 cm/sec for the same depths
at one point in Cook Inlet.
Salinity in Cook Inlet varies seasonally due to variations in fresh water inflow. During
summer (May through September) river discharges decrease the salinity of the upper Inlet. During
winter, intrusion by more saline oceanic waters increase salinity throughout the Inlet. At the mouth
of the Inlet salinity value remain nearly constant at 32 ppt. As a result of ckculation patterns,
salinity on the eastern side of Lower Cook Inlet tends to be higher than the western side.
Cook Inlet is characterized by large quantities of glacial sediments washed into the upper
inlet from seven major glacier-fed rivers. Sediment inflow from glacial sources is seasonal with
larger amounts of glacially-derived sediment occurring in summer months. In upper Cook Inlet,
clay- and silt-sized particles are kept in suspension by tidal currents. The bulk of this fine
sediment is transported down the west side of the inlet and deposited in the Aleutian Trench
beyond Kodiak Island. Extreme ranges of sediments vary from 1 to 2 mg/1 at the mouth of Cook
Inlet to over 2,000 mg/1 in Knit Arm (Dames & Moore, 1978).
3.3.3 Offshore California
The Southern California Bight is the area of the California coastline from Point Conception
in the north to San Diego in the south. Currently, it is the only area with oil and gas activity in the
offshore California discharge region. The area has three principle features: (i) a narrow
continental shelf ranging in width between 3 km and 10 km; (ii) distinct basins with depths to 1 km;
and (iii) a number of islands.
Circulation on the shelf of southern California is not well defined (MMS, 1991), The
offshore flow is generally a counter-clockwise flow from the shelf and slope area north of Point
Conception past the channel islands and then eastward where it intersects the shelf at a point not
precisely determined.
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3-12 .
The major surface currents offshore California are the California Current (mean speed about
15 cm/sec) that flows generally southward and affects areas further offshore and the Davidson
Current (speeds up to 15-30 cm/sec) that flows northward closer to the shore. The Davidson
Current mainly occurs in areas where oil and gas leases occur offshore California (MMS, 1985).
3.4 Recreational and Commercial Fisheries
3.4.1 Gulf of Mexico
Recreational Finfish
In the Gulf of Mexico, 18 million recreational fishing trips (excluding Texas) were taken in
1998 (NMFS,1999). In Texas 266,500 man-hours of sport-boat fishing were reported for the
Exclusive Economic Zone in 1991 (NMFS, 1997). Data from the National Marine Fisheries
Service (NMFS) Fisheries Statistics Survey are presented in Exhibit 3-6 for recreational fish
catch in Gulf of Mexico states, excluding Texas. Texas data are maintained by the state and not
reported to NMFS.
Commercial Shrimp
Gulf of Mexico commercial shrimp fisheries include mainly brown, pink, white, and
northern shrimp. According to NMFS (1999), the commercial shrimp landings in the Gulf of
Mexico represented 71% and 83% of the total US landings by weight in 1997 and 1998,
respectively with 205.5 million and 230.0 million pounds of shrimp landed each year. The value
of these shrimp represented 80% and 83% of the total US shrimp landings by weight for those
respective years at $437 million and $429 million. The commercial shrimp landings for Gulf of
Mexico states is presented in Exhibit 3-7.
As presented in the offshore Environmental Assessment (Avanti Corporation, 1993), the
state reporting the landing does not necessarily represent the state in which the shrimp were
caught EPA has used the catch:landings ratios used in the offshore assessment to adjust the
landings figures by factors of 123% for Louisiana and 85% for Texas. Also, as developed for the
offshore analysis, the total catch is adjusted to calculate the portion caught in areas potentially
affected by SBF discharges, i.e., beyond 3 miles from shore. These calculations are presented in
Appendix 3-1.
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3-13
Exhibit 3-6. Gulf of Mexico Recreational Fisheries Catch (pounds)
State
W. Florida
Alabama
Mississippi
Louisiana
Total
1997
21,002,819
4,209,083
1,975,874
2,332,590
29,520,366
1998
15,306,697
2,347,612
958,700
1,536,503
20,149,512
Average
18,154,758
3,278,348
1,467,287
1,934,547
24,834,939
Source: NMFS, 1999
3.4.2 Cook Inlet, Alaska
Recreational Finfish
Cook Inlet area waters provided over 50% of the total (saltwater and freshwater)
sportfishing days in Alaska in 1992 with an estimated 375,993 saltwater recreational fishing days
recorded (Mills, 1993). Most of the recreational fishing in the inlet is for halibut and chinook
salmon.
Commercial Shrimp "
There has been no commercial shrimping in Cook Inlet since January 1, 1997. The Alaska
Board of Fisheries mandated closures for Inner Cook Inlet (Kachemak Bay) in 1988 and Outer
Cook Inlet since January 1997 (Beverage, 1998). These closures were due to insufficient
information on the biology and stock status of the coonstriped shrimp, which was the primary
species sought by Alaskan commercial shrimpers. There is no information that indicates that these
closures will be lifted in the near future.~~;"
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3-14
Exhibit 3-7. Gulf of Mexico Commercial Shrimp Catch (pounds)
onnmp
Species
Brown
1997
1998
Average
Northern
1997
1998
Average
Pink
1997
1998
Average
White
1997
1998
Average
Rock
1997
1998
Average
Other
Marine
1997
1998
Average
Florida
528,113
1,188,219
858,166
0
0
0
16,508,557
19,797,725
18,153,141
1,261,079
746,059
1,003,569
1,189,038
3,429,676
2,309,357
1,409,231
1,612,134
1,510,683
Mississippi
9,902,044
10,447,157
10,174,601
0
0
0
259,483
268,633
264,058
2,158,277
5,274,399
3,716,388
17,122
84,655
50,889
0
0
0
Alabama
9,371,357
10,983,270
10,177,314
28,054
9,539
18,797
2,100,727
2,781,972
2,441,350
1,189,966
2,400,442
1,795,204
536,509
3,628,898
2,082,704
325,008
272,371
298,690
Louisiana
43,137,058
39,853,726
41,495,392
0
14,236
7,118
77,697
21,862
49,780
36,249,298
48,152,332
42,200,815
5,634
4,059
4,847
2,601,310
1,369,060
1,985,185
Texas
44,169,655
46,630,671
45,400,163
0
0
0
1,120,552
1,408,291
1,264,422
19,401,497
17,525,344
18,463,421
547,723
579,371
563,547
5,659,503
4,463,913
5,061,708
Total
Gulf of
Mexico
107,108,227
109,103,043
108,105,635
28,054
23,775
25,915
20,067,016
24,278,483
22,172,750
60,260,117
74,098,576
67,179,347
2,296,026
7,726,659
5,011,343
9,995,052
7,717,478
8,856,265
Total Texas
and
Louisiana
87,306,713
86,484,397
86,895,555
0
14,236
7,118
1,198,249
1,430,153
1,314,201
55,650,795
65,677,676
60,664,236
553,357
583,43C
568,394
8,260,813
5,832,973
7,046,893
Source: NMFS, 1999
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3-15
3.4.3 Offshore California
Recreational Finfish
In southern California an estimated 958 people participated in 3,519 fishing trips in 1996
(NMFS, 1997). The finfish catch reported for 1995 and 1996 were 4,771,722 pounds and
3,191,205 pounds, respectively (NMFS, 1997).
Commercial Shrimp
Commercial shrimping occurs in the same general location as oil and gas activities. Primary
species caught in offshore California waters are ridgeback and spot prawns. These two species
accounted for 5 percent of all the 1997 shrimp landings in California. There were 450,189 Ibs of
spot prawn and 385,931 Ibs of ridgeback prawns landed in Southern California ports in 1997 (CA
DFG, 1998). Shrimping for ridgeback and spot prawns occurs in water depth between 50 fathoms
and 200 fathoms and outside state waters.
The CA Department of Fish and Game (CA DFG) records shrimp catch data in 6- by 10-
mile blocks. By identifying the blocks that are within the species' depth range and outside state
waters, shrimp catch can be expressed on a pounds per square mile basis. The depths were taken
from NOAA nautical charts and catch blocks were taken from Southern California Fisheries
Charts, provided by CA DFG. There were 44, 10-by-6 mile blocks that were identified as having
the 50- to 200-fathom depth range and existing outside state waters. From these blocks, a
shrimping area of 264,000 square miles was determined. Using the total pounds of ridgeback and
spot prawns reported in southern ports, a catch rate of 3.17 pounds of shrimp per square mile is
used in this analysis.
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-------
4-1
4. WATER QUALITY ASSESSMENT
4.1 Introduction
EPA based the methodologies for assessing both surface and pore water quality impacts
from the discharge of SBF-cuttings on the methodologies used to assess the discharge of water-
based fluids (WBFs) and associated cuttings (WBF-cuttings) for the offshore effluent limitations
guidelines (ELG). The methodology for the offshore guidelines is presented in Avanti
Corporation, 1993. Most of the studies related to discharges of cuttings at levels of adhered fluids
greater than the controlled SBF discharge levels under BAT and NSPS. However, there are
several major differences in the analyses, most notably the absence of bulk drilling fluid
discharges in the SBF guidelines. In the offshore ELG, these bulk discharges were a major
wastestream and numerous existing drilling fluid characterization and transport studies were used
as sources of data for the water quality assessment. In the current SBF-cuttings discharge impact
analysis, surface water quality assessments rely on modeling data presented in a study (Brandsma,
1996) of the post-discharge transport behavior of oil and solids from cuttings contaminated with
oil-based fluids (OBF-cuttings). Due to the similar hydrophobic and physical properties between
SBFs and OBFs, EPA assumes that above 5% retention, that dispersion behavior of SBF-cuttings
is similar to that of OBF-cuttings when discharged following shale shaker only (i.e. baseline
technology) treatment of cuttings. However, at controlled discharge levels reflecting add-on
(BAT) treatment the cuttings are expected to disperse similar to WBF-cuttings.
In addition, the offshore ELG only examined impacts in the Gulf of Mexico. For the SBF
guidelines, EPA considered the impacts in offshore California and Cook Inlet, Alaska separately
from the Gulf of Mexico. Although the analysis methodology does not change between regions,
data used to conduct the water quality assessment contain certain assumptions specific to each
region, for example, current speed.
For the pore water quality assessment, the absence of bulk drilling fluid discharges greatly
affects the annual pollutant loadings. EPA applied the same methodology used for the offshore
ELG in assessing the effects of SBF-cuttings discharges on pore water quality for the current
industry practice and the discharge options.
The analyses in this chapter are somewhat conservative due to the assumption that
discharged pollutants immediately leach into the water column or into the pore water. In the water
column, total organic pollutant discharge concentrations are assumed to represent the soluble
concentration. Metals are assumed to leach immediately into the water column at pollutant-
specific amounts determined for mean seawater pH (as derived in Avanti Corporation, 1993;
-------
Appendix C). In the pore water, pollutant-specific partition coefficients are used for organic
pollutants (from EPA's IRIS) to determine soluble concentrations. The mean seawater leach
factors are used for metals in the same manner as used for the water column concentrations. For
both organic pollutants and metals, the total leached concentration is assumed to be immediately
available in the pore water at the ratio determined for mean seawater pH.
In general, the methodology consists of modeling incremental water column and pore water
concentrations and comparing them to EPA water quality criteria/toxic values for marine acute,
marine chronic, and human health protection. Additionally, EPA used the proposed sediment
guidelines for protection of benthic organisms to assess potential impacts from a group of select
metals in pore water (EPA, 1998ab). Note that all of these comparisons are performed only for
those pollutants for which EPA has numeric criteria. Those pollutants include priority and .
nonconventional pollutants associated with the drilling fluid barite and with contamination by
formation (crude) oil, but do not include synthetic base fluids themselves. Potential impacts from
synthetic base fluid compounds are described in Chapters 6 through 9 of this document.
4.2 Surface Water
To evaluate the relative water quality impacts of the current industry practice and
regulatory options, EPA estimates the water column concentration of pollutants present in SBF
drilling discharges under regulatory discharge options and compares them to Federal water quality
criteria/toxic values. This comparative analysis applies only to those pollutants found in SBF
discharges, and for which EPA has published numeric criteria, as presented in Exhibit 4-1. Note
that there are no criteria for the synthetic-based fluid compounds themselves.
In order to determine the water column pollutant concentrations, EPA used data regarding
the transport of discharged drill solids and corresponding oil concentration in the water column.
The study was performed by Brandsma (1996) and the data are published in the April 1996 E&P
Forum Summary Report No. 2.61/202. Because of the extensive North Sea use of oil-based
drilling fluids (OBF) and discharge of OBF-cuttings, the E&P Forum sponsored the research
project to evaluate the modeled dispersement of treated versus untreated OBF-cuttings. Following
is a description of the Brandsma (1996) study from that E&P report.
Brandsma modeled the discharge of nine treatments of cuttings obtained from a North Sea
drilling platform to obtain: (1) a maximum deposition density (g/nf) of cuttings and oil; (2) water
column concentrations of suspended solids and oil; (3) the maximum thickness (cm) of cuttings
deposited on the seabed; and (4) the seabed area (ha) that would achieve a 100 ppm oil content
threshold in the upper 4 cm or 10 cm of the sediment.
-------
4-3
Exhibit 4-1. National Recommended Water Quality Criteria For SBF Pollutants
(a)
(b)
Pollutant
Antimony
Arsenic
Cadmium
Chromium (VI)
Copper
Fluorene
Lead
Mercury
Nickel
Phenol
Selenium
Silver
Thallium
Zinc
Marine Acute
Criteria
(|ig/l)
69
42
1,100
4.8
210
1.8
74
290
1.9
90
Marine Chronic
Criteria
(Hg/1)
36
9.3
50
3.1
8.1
0.94
8.2
71
81
Human Health
Criteria
(Hg/1) (a)
4,300
0.14(b)
14,000
0.051
4,600
4,600,000
11,000
6.3
69,000
Human health criteria for consumption of organisms only; risk factor of 10 for carcinogens.
Source: EPA, 1999b. .
Note: The revised water quality criteria list this criterion with the footnote that EPA is "reassessing the
criteria for arsenic and will publish revised criteria as appropriate."
The treatment technologies included: (1) no treatment (lab formulated control), (2)
untreated cuttings from shale shakers, (3) centrifugation, (4) solvent extraction, (5) thermal
treatment, and (6) water washing. The bulk densities of the cutting ranged from 1,830 g/1 to 2,430
g/1; oil content for the six types of cuttings ranged from 0.02% (dry weight basis) to 19.6%.
The author simulated four sites in the North Sea: Southern (30m water depth and depth-
averaged, root mean-squared current speed of 0.37 m/s); Central (100 m water depth and current
speed of 0.26 m/s); Northern (150 m water depth and current speed of 0.22 m/s); and
Haltenbanken (250 m water depth and current speed of 0.10 m/s).
The Offshore Operators Committee (OOC) drilling and production discharge model was
used to simulate the concentrations and deposition of discharged cuttings. The OOC model
utilized a mixture of 12 profile size classes of mud and cuttings particles (with adsorbed oil) and
water. All other discharge conditions were fixed. All discharges simulated a 68.5-hour discharge
of 152 m3 of cuttings from a 0.3 m diameter pipe shunted to a depth of 15.2 m below mean sea
-------
4-4 .
level. This cuttings volume is the volume expected from a single well section of OBF-cuttings.
Results presented are based on these 152 m3 model efforts, however, results are scaled up to a 300
m3 volume which was later determined by the project steering committee to be more representative
of actual OBF-cuttings volumes generated using DBFs (representing two well sections).
Hydrographic conditions were conservatively selected to maximize predicted cuttings
deposition on the seabed by choosing the minimum water column stratification at each site. The
result is no density gradient at all sites but the Haltenbanken site, which exhibited only a weak
(0.0016 kg/mVm) gradient.
Water column results were determined at a radial distance of 1000 in downstream. For
untreated and centrifuged OBF-cuttings, projected water column oil concentrations at 1000 m were
below maximum North Sea background levels at all four sites; all other treatments resulted in
projected 1000 m oil concentrations that exceeded maximum background levels (except through
treatment at the Haltenbanken site). The explanation for this apparent conundrum is that while
treatments other than centrifugation also reduce oil content (from an untreated level of 15.8%
[w/w] to a range of 0.3% to 5.1%), these treatments also generate cuttings with finer particle sizes.
Thus, according to the model, the untreated and centrifuged OBF-cuttings would not reach the 1000
m mark to the same extent that the treated OBF-cuttings would because the finer particles created
by the treatment have lower settling velocities and are transported farther in the water column
(Brandsma, 1996).
Although Brandsma (1996) does not present oil concentration data for a radial distance of
100 m (the edge of the mixing zone established for U.S. offshore discharges by Clean Water Act
Section 403, Ocean Discharge Criteria, as codified at 40 CFR 125 Subpart M), the study does
present data on suspended solids and oil concentration as a function of transport time. Using
current speeds representative of each geographic area (Gulf of Mexico; Cook Inlet, Alaska; and
offshore California) and the transport times reported by Brandsma, EPA derived the corresponding
oil concentrations and dilutions at 100 m. For example, assuming a mean current speed of 15 cm/s
as representative of the Gulf of Mexico, a transport time of approximately 11 minutes is derived as
the time required for the plume to reach 100 m (100 m/0.15 m/sec). Using data obtained from
Brandsma's 1996 study, EPA conducted a regression analysis to determine the oil concentration at
selected transport times. Based on the mean initial oil concentration of the 9 cuttings cases
presented in the study (5.5% in water-washed cuttings), the dilutions achieved can be estimated for
a selected time (i.e., distance) in the following manner. The 5.5% (w/w) oil content converts to
55 g oil/kg wet cuttings. Based on a reported mean OBF-cuttings density of 2.050 kg wet
cuttings/1, the initial oil concentration of 112,750 mg oil/1 (55 g/kg x 2.050 kg/1) is used to
determine the dilutions achieved. For the Gulf of Mexico example, the oil concentration at 11
minutes of 3.0 mg/1 is used to calculate a 37,425-fold dilution (112,750 mg/3.0127 mg) at
-------
• - ; 4-5
11 minutes (Bowler, 1999). As described above, 11 minutes represents the estimated time at
which the plume would reach the edge of the mixing zone at 100 meters.
Projected water column pollutant concentrations at the edge of a 100-m mixing zone are
calculated by dividing the drilling waste pollutant concentration by the dilutions available. The
effluent concentrations for metals are further adjusted by a leach factor to account for the portion of
the total metal pollutant concentration that is dissolved and therefore available in the water
column. In terms of metal concentrations, this analysis is conservative in that it assumes that all
leachable metals are immediately leached into the water column.
Exhibit 4-2 summarizes the water quality analyses for Gulf of Mexico, Cook Inlet, Alaska,
and offshore California water column pollutant concentrations at 100 m from SBF-euttings '
discharges. The results show that no exceedances of any Federal or state water quality criteria or
standards are expected using current technology or the discharge option.
4.2.1 Gulf of Mexico
Appendix 4-1 compares the projected pollutant concentrations for Gulf of Mexico
discharges of SBFs with the Federal water quality criteria under the discharge scenarios for
baseline and the two BAT discharge options. For this analysis, and all subsequent water quality
and pore water quality analyses in this report, the zero discharge option is not presented in tabular
form. Because no drilling wastes are discharged under the zero discharge option, there are no
water quality criteria concerns to assess.
The water column pollutant concentrations for all four model wells (deep water
exploratory, deep water development, shallow water exploratory, and shallow water
development) are the same within each discharge scenario. This occurs because only the total
discharge volume for each of the model wells varies, not the discharge rate or individual pollutant
concentrations. The reader should also note that in the exhibits found in Appendix C, only the most
stringent water quality criterion is listed for each pollutant. Any exceedances of water quality
criteria are detailed in the footnotes of each table.
-------
4-6
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4-7
When comparing the Federal water quality criteria to the SBF concentration in the water
column at 100 meters from the discharge, no exceedances of any of the Federal water quality
criteria occurred for any model wells in the Gulf of Mexico using the current technology, nor under
either the discharge or zero discharge options.
4.2.2 Cook Inlet, Alaska
For the Cook Inlet analysis, EPA compared pollutant concentrations resulting from an
estimate of the discharge of SBF-cuttings to both Federal criteria and state water quality standards
because the discharges occur hi state waters. The Alaska standard for "toxic and other deleterious
organic and inorganic substances" states that "individual substances may not exceed criteria hi
EPA, Quality Criteria for Water (ADEC, 1999). A summary of applicable Alaska standards for
_ waters classified as marine waters for growth and propagation offish, shellfish, and other aquatic
life, and wildlife are presented in Exhibits 4-3. Enforceable Alaska state water quality standards
are summarized hi Exhibit 4-4.
EPA determined the dilutions for assessment of compliance with water quality criteria and
standards using the same methodology as for the Gulf of Mexico analysis. A current speed of
40 cm/sec was used (EPA Region 10, 1984), resulting in a transport time of 4.2 minutes to reach
the edge of the 100-meter mixing zone. The midpoint oil concentration from Brandsma (1996) at 4
minutes is 11.8 mg/1. This concentration is a 9,551-fold dilution from the initial discharge
concentration of oil (112,750 mg/1), (Bowler, 1999).
The current operating practice hi Cook Inlet, Alaska is zero discharge of SBF-cuttings.
Since there are no impacts to surface waters, a numerical analysis was not conducted. For the
discharge options, Appendix 4-2 presents the water column concentrations of pollutants at 100
meters from the discharge point and compares them to Federal water quality criteria and Alaska
state standards. Under either of the discharge options, there are no exceedances of the Federal
criteria or state numerical standards hi Cook Inlet, Alaska.
4.2.3 Offshore California
For the offshore California analysis, EPA compared pollutant concentrations resulting from
an estimate of the discharge of SBF-cuttings hi offshore California waters to Federal water quality
criteria to determine compliance with these guidelines. EPA determined the dilutions for
assessment of compliance with water quality standards using the same methodology as for the Gulf
of Mexico analysis. A current speed of 30 cm/sec was used (MMS, 1985), resulting
-------
4-8
Exhibit 4-3. Applicable Alaska State Water Quality Standards
Toxics and Other Deleterious Organic
and Inorganic Substances
Individual substances may not exceed EPA Quality
Criteria for Water.
No toxic substances in water or sediment that cause toxic
effects on aquatic life.
Substances may not impart undesirable odor or taste in
fish or other organisms, as determined by bioassay or
organoleptic tests.
Petroleum Hydrocarbons, Oils and
Grease
Total aqueous hydrocarbons (TaqH) < 15 pg/1 in water
column.
Total aromatic hydrocarbons (TAH) < 10 ug/1 in water
column.
No concentrations in sediments that cause effects to
aquatic life.
Water and shoreline must be free from floating oil, film,
sheen, or discoloration.
Residues (floating solids, debris, sludge,
deposits, foam, scum, or other residue)
No acute or chronic levels as determined by bioassay or
other methods.
No film, sheen, or discoloration of water or shorelines.
No leaching of toxic substances.
No sludge, solid, or emulsion deposited beneath or upon
the surface of the water, within the water column, on the
bottom, or upon adjoining shorelines.
Human Health
Not to exceed 10~s lifetime incremental cancer risk level.
Whole Effluent Toxicity
No chronic toxicity (expressed as <1.0 chronic toxic units
[100/No effect concentration (NOEC)]) at discharge point or
at mixing zone (if allowed) based on minimum effluent
dilution achieved in the mixing zone.
Source: Alaska Department of Environmental Conservation. 1999. 18 AAC 70 Water Quality Standards, As
amended through May 27, 1999. 56pp.
-------
4-9
Exhibit 4-4. Enforceable Alaska State Standards under the Clean Water Act
(in ug/1, unless otherwise noted)
Pollutant
Naphthalene
Fluorene
Phenanthrene
Phenol
Cadmium
Mercury
Antimony
Arsenic
Beryllium
Chromium IE
Chromium VI
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Marine ^
Acute
2,350 V
NA ;:;:^
na \ -
5,800 ?
43 ::£
2.1 . ™Z
NA -~^.
69 '.' -^i-
NA ;-:': ^
10,300 7K
1,100 .-Tit
2.9 .m
140 .•
75 .;:V;.
300 ; "
2.3 ^
2,130 ;.;;"
95 -";*;-..
Marine
Chronic
NA
NA
NA
NA
9.3
0.025
NA
36
NA
NA
50
4.0
5.6
7.1
71
NA
NA
50
Human
Health (10'5)
NA
NA
NA
300
NA - ::
0.146
45,000 :
50 -
641 ng
NA
NA
NA
NA
100
NA "*
NA
48.0
NA T
Source: Petrazzuolo, 2000
-------
4-10
resulting in a transport time of 5.5 minutes to reach the edge of the 100-meter mixing zone. The
midpoint oil concentration from Brandsma (1996) at 5 minutes is 8.7 mg/1. This concentration is a
12,909-fold dilution from the initial discharge concentration of oil (112,750 mg/1), (Bowler,
1999).
The current practice in offshore California is zero discharge of SBF-cuttings. Since there
are no impacts to surface waters, a numerical analysis was not conducted. For the discharge
options, Appendix 4-3 presents the water column concentrations of pollutants at 100 meters from
the discharge point and compares them to Federal water quality criteria. Under either of the
discharge options, there are no exceedances of the Federal water quality criteria in offshore
California.
4.3 Sediment Pore Water Quality
EPA calculated sediment pollutant levels based on the assumption of a uniform distribution
of the annual mass loadings of pollutants from model operations into a defined area of impact.
Using the derived sediment pollutant concentrations, EPA assessed sediment pore water quality.
A summary of the pore water quality analyses for discharges of SBF-cuttings in the Gulf of
Mexico, Cook Inlet, Alaska, and offshore California is presented in Exhibit 4-5.
4.3.1 Gulf of Mexico
To assess the pore water quality impacts of the discharge of SBF-cuttings on the benthic
environment, EPA determined the pollutant concentrations in the pore water for each model well
and each discharge scenario at the edge of the 100-meter mixing zone. EPA uses 100 m as the
edge of the mixing zone established for U.S. offshore discharges by Clean Water Act Section 403,
Ocean Discharge Criteria, as codified at 40 CFR 125 Subpart M. EPA then compared these
projected pore water concentrations of pollutants from the SBF-cuttings to Federal water quality
criteria to determine the number of exceedances and the magnitude of each exceedance. Following
is a detailed explanation of the methodology used to assess pore water quality.
The pore water quality analysis of the offshore Effluent Limitations Guidelines
characterized sediment pollutants through a number of field surveys of both exploratory and
development operations. These surveys predominantly measured sediment barium content, which
was considered the best marker for assessing transport and fate of the particulate fraction of water-
based drilling fluids. In this current environmental assessment, EPA again assessed field surveys
but the sediment concentration of synthetic base fluid was considered the most reliable marker of
SBF-cuttings transport. After publication of the proposed SBF rule, EPA received
-------
4-11
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4-12 '
additional survey data and compiled sediment synthetic base fluid concentration data from 17
wells. Eleven wells were drilled in the North Sea and six in the Gulf of Mexico. If the survey
data did not include data for a 100-m sampling location, EPA linearly extrapolated the existing
data points to 100 m. A summary of thelQO-m sediment synthetic base fluid concentrations is
presented in Exhibit 4-6. Data from all the sampling transects presented in a given survey are
included in the analysis. Because concentrations were averaged over different transects per well,
that is, not consistently down current, the resultant synthetic base fluid concentration represents the
average concentration found at any given point 100 m around a well as opposed to the maximum
(i.e., down current) concentration. Given the reported depths and discharge volumes of the
studies, the calculated average concentration most closely represents current practice for a Gulf of
Mexico shallow water exploratory model well.
In order to determine SBF-cuttings pollutant concentrations for other model well types,
EPA assumed that the relative concentrations or proportions between the base fluid and other
pollutants as found in the SBF are maintained after discharge and transport. Therefore, to project
the sediment concentration of each pollutent, EPA multiplied the ratio of each pollutant to the
synthetic base fluid by the average 100-m base fluid concentration (9,718 mg synthetic/kg for the
shallow water exploratory model well;: see Exhibit 4-5). For each model well, this factor is
further adjusted to account for the varying total amount of oil (synthetic plus formation oil)
discharged under Baseline and the two discharge options.. For example, EPA determined that the
shallow development well would discharge only 47.7% of the oil as the shallow exploratory well
under Baseline. Therefore, the sedimentpollutant concentrations for the shallow development
well are 47.7% of those for the shallow exploratory well. For the deep wells under BPT Baseline
(using the shallow water exploratory well as 100%), these factors are 160.6% and 72.2% for
exploratory and development well pollutants, respectively. Appendix D presents the ratios of the
model wells under the two discharge options.
The sediment pollutant concentrations are converted into pore water concentrations. For
metals, the mean seawater leach factors of trace metals hi barite are used. For organic pollutants,
partition coefficients are used to projecfpore water concentrations. Partition coefficients estimate
the ratio of sediment to pore water concentration as the product of the fraction of organic carbon
(foe) and the octanol-water partition coefficient (K^). For sediments, the KOW = the partition
coefficient for organic particle carbon (iC). Therefore, Ksed = f^ * KOC. Both the f^ and K^ used
for this analysis are presented in Exhibit 4^7 and are based on the offshore environmental analysis
(Avanti Corporation, 1993). The leach factors and partition coefficients are summarized in
Exhibit 4-7. The sediment concentration multiplied by the pollutant specific leach factor or
inverse of the partition coefficient results .in the amount of pollutant available in the pore water.
To calculate the interstitial (pore water) concentration of each pollutant, the available pollutant
-------
4-13
Exhibit 4-6.. Summary of Synthetic Base Fluid Concentrations at 100 Meters
Data Source
Candler et al., 1995
Daanetal., 1996
Smith and May, 1991 in
Schaanning, 1995
Gj0s, 1995a in
Viketal.,1996a
Gj0s. 1995b in
Viketal, 1996a
Gj0s, 1992 & 1993 in
Viketal., 1996a
Feldstedt, 1995 in
Viketal., 1996a
Fechhelm, et al., 1999
1997 Study
Study
Site/Location
MPI-895;
Gulf of Mexico
K14-13;
North Sea
Ula 7/12-9;
North Sea
Tordis Well;
North Sea
Loke Well;
North Sea
SleipnerAWell;
North Sea
Sleipner 0 Well;
North Sea
Gyda 2/1-9;
North Sea
Ula 2/7-29;
North Sea
Ula7/12-A6;
North Sea
Mississippi
Canyon;
Gulf of Mexico
Depth
(m)
39
30
67
181 -218
76-81
76-81
— •
70
67
67
565
Base Fluid
Type
PAO
Ester
Ester
PAO
Ester
Ester
Ester
Ether
Acetal
Acetal
PAO/Ester
Cone, at 100 m for all
Transects (mg/kg) (a)
N: 39,470
E:153
S: 2,010
W:494
N:200
SW: 46,400
SE:97
SW:<1
NW:<1
E:229
S:12
NE: 15,990
146
622
68
3,850
SW:420
SE: 200
SW: 24,833
SE: 10,000
NE: 550
SE: 256
SW: 643
NW:67
NW:NA
SE: 3,731
NE: 187,345
SW: 5,792
(a) More than one value per well represents values from different sampling transects.
-------
4-14
Exhibit 4-6. (Continued) Summary of Synthetic Base Fluid Concentrations at 100 Meters
Data Source
Neff et. al., 2000
Neffetal.,2000
Unocal Public
Comments
Unocal Public
Comments
Unocal Public
Comments
Unocal Public
Comments
Study
Site/Location
UKOOAwell;
North Sea
UKOOAwell;
North Sea
VermillionSS
(Well 2);
Gulf of Mexico
VermillionSS
(Well 3);
Gulf of Mexico
VermillionSS
(Structure B);
Gulf of Mexico
VermillionSS
(Structure M);
GulfofMexico
Depth
(m)
150
185
12
12
12
12
Base Fluid
Type
Ester
LAO
Average concentration at 100 meters (represents a Gulf of Mexico shallow
water exploratory model well)
Average concentration at 100 meters (excluding the 6 shallowest
discharges; represents Cook Inlet, Alaska and offshore California shallow
water exploratory model well)
Cone, at 100 m for all
Transects (mg/kg) (a)
N:0
SW: 1,074
S:0
W:0
NW: 1,942
SE: 2.9
NE:0
E: 1,356
SE:50
SW:58
S:45
E:74
NE:50
NW: 14,546
NW:0
W: 17
N:0
NE:59
9,718
13,052
(a) More than one value per well represents values from different sampling transects.
sediment concentration is multiplied by the dry weight of sediment in a 1m x 1m x 0.05m unit
volume and divided by the volume of water per unit volume of sediment. Based on the offshore
Environmental Assessment, the dry weight of sediment equals 35.5 kg and the volume of pore
water approximated from a dry sediment specific weight of 2 g/ml is 32.5 1 (Avanti Corporation,
1993).
The calculated pore water concentrations of pollutants are then compared to their
respective EPA marine water quality criteria to determine the nature and magnitude of any
projected water quality exceedances. Appendix 4-4 presents the pore water quality analyses and
-------
4-15
Exhibit 4-7. Trace Metal Leach Factors and Organic Pollutant Partition Coefficients
Trace Metal
Cadmium
Mercury
Arsenic
Chromium
Copper
Lead
Nickel
Zinc
Barium
Iron
Organic Pollutant
Naphthalene
Fluorene
Phenanthrene
Phenol
Mean Seawater Leach Factor
0.11
0.018
0.005
0.034
0.0063
0.02
0.043
0.0041
0.0021
0.13
I/Partition
^c oc Coefficient
1,995 0.63% 0.0796
3,900 0.63% 0.0407
14,000 0.63% 0.0113
14 0.63% 11.34
Source: Offshore Environmental Assessment (Avanti Corporation, 1993).
comparisons to the EPA water quality criteria for Gulf of Mexico discharges from wells using the
current and discharge option technologies.
4.3.2 Cook Inlet, Alaska and Offshore California
To assess the pore water quality impacts for Cook Inlet, Alaska and offshore California,
EPA again used the synthetic base fluid concentrations presented in Exhibit 4-6 to estimate the
concentration of synthetic fluids at 100 meters from the discharge. Due to the increased energy and
depth of Cook Inlet and offshore California, six of the studies in Exhibit 4-6 were eliminated from
-------
4-16 ;
the calculation of the average synthetic base fluid concentration at 100 meters. All of the
eliminated studies included discharges in less than 40 meters total water depth (Candler et al.,
1995, Daan et al., 1996, and all of the Unocal public comment wells).
The resulting average base fluid concentration at 100 m (13,052 mg/kg) is used to calculate
the pore water concentrations of individual pollutants in synthetic fluids for a shallow water
exploratory model well. As for the Gulf of Mexico analysis, the concentration of base fluid at 100
meters is multiplied by the proportion of total oil discharged relative to a shallow exploratory
well to calculate the other model well type pollutant concentrations. These resulting concentration
at 100 meters for each pollutant is multiplied by the pollutant-specific leach factor for metals or
divided by the partition coefficient for organic pollutants to derive pore water pollutant
concentrations.
EPA projects that only development wells will be drilled in both Cook Inlet, Alaska
(shallow only) and offshore California (both shallow and deep). EPA does not project the drilling
of any exploratory wells in these areas, and for this reason model results concerning exploratory
wells are not shown. Operators in Cook Inlet, Alaska and offshore California currently cannot
discharge SBF-cuttings and water quality impacts, including pore water, are not presented for the
Baseline. The pore water pollutant concentrations for the two discharge options are compared to
Federal water quality criteria and Alaska state standards in Appendixes 4-5 and 4-6 for Cook
Inlet, Alaska and Offshore California, respectively.
4.4 Sediment Guidelines for the Protection of Benthic Organisms
An additional method for assessing potential benthic impacts of certain metals is EPA's
proposed sediment guidelines for the protection of benthic organisms (EPA, 1998b). These
proposed guidelines are based on an equilibrium partitioning (EqP) approach to determine
guidelines based on "numerical concentrations for individual chemicals that are applicable across
the range of sediments encountered in practice." The EqP sediment guidelines (ESG) for the six
metals copper, cadmium, nickel, lead, silver, and zinc account for the additive toxicity effects of
these metals. They are derived by two procedures: (a) by comparing the sum of the metal'^ molar
concentrations, measured as simultaneously extracted metal (SEM), to the molar concentration of
acid volatile sulfide (AVS) in sediments:
/
£i [SEM] £ [AVS]
or (b) by comparing the measured interstitial water [i.e., pore water] concentrations of the metals
to water quality criteria final chronic values (FCVs):
-------
; 4-17
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5-1
5. HUMAN HEALTH RISKS
5.1 Introduction
This portion of the environmental analysis presents the human health-related risks and risk
reductions (benefits) of current BPT baseline technology and the two discharge regulatory options
for the Gulf of Mexico and Cook Inlet, Alaska geographic areas. EPA does not project that any
offshore California wells will be drilled using SBFs based on industry information provided to
EPA after publication of the NODA. Industry projections of SBF usage show that SBFs would not
be used for drilling wells in the offshore California area, even under a controlled discharge
option. Therefore, human health impacts are not presented for offshore California. However,
should industry practices change so that SBFs would be used, EPA has modeled impacts resulting
from drilling one shallow water and 11 deep water development wells in offshore California.
Based on the modeling results, no human health impacts are projected in offshore California
(results are presented in Appendix 5-1).
EPA based the health risks and benefits analysis on human exposure to carcinogenic and
noncarcinogenic contaminants through consumption of affected seafood; specifically,
recreationally-caught finfish and commercially-caught shrimp. EPA used seafood consumption
and lifetime exposure duration assumptions to estimate risks and benefits under each of the
discharge scenarios for the three geographic regions where the discharge of SBF-cuttings will be
affected by this rule. The analysis is performed for those contaminants for which bioconcen-
tration factors, oral reference doses (RfDs), or oral slope factors for carcinogenic risks have been
established. Thus, the analysis considers contaminants associated with the drilling fluid barite and
with contamination by formation (crude) oil, but does not consider the synthetic base compounds
themselves.
5.2 Recreational Fisheries Tissue Concentrations
Exposure of recreational finfish to drilling fluid contaminants occurs through the uptake of
dissolved pollutants found in the water column. Instead of using the water column pollutant
concentrations at the edge of the mixing zone (as for the water quality analyses), EPA calculates an
average water column concentration of each pollutant for the area within a 100-m radius of the
discharge. The 100 m edge of mixing zone was established for U.S. offshore discharges by Clean
Water Act Section 403, Ocean Discharge Criteria, as codified at 40 CFR 125 Subpart M. As
described in Chapter 4, Brandsma's 1996 study was used to determine base fluid concentrations at
specified distances from a discharge point. Also as presented in Chapter 4, Brandsma does not
provide concentrations as a function of distance, but rather as a function of tune. Therefore, to
calculate an average concentration within 100 m, the time required for transport to the edge of the
-------
5-2 _
mixing zone was calculated as the quotient of the distance to the edge of the mixing zone and the
current speed (100 meters/current speed, in m/sec). Based on this transport time, equal time
intervals (and therefore radial distances) were chosen to create a series of base fluid
concentrations at varying radii across the total radius of the mixing zone. These concentrations
were used to calculate the dilutions achieved at these distances using the method described in
Chapter 4 (section 4.2). The average dilution for the area within 100 meters was derived from
these estimated dilutions between the discharge point and the 100-meter boundary. The base fluid
concentrations from Braridsma (1996), the calculated dilutions, and the average dilutions used are
presented below in the discussions for each geographic region.
The average dilution available within 100 m is used to determine the ambient bioavailable
concentrations of pollutants associated with the SBF within the effluent plume by multiplying'the
average number of dilutions by the respective initial pollutant concentrations. For metals., these
pollutant concentrations are further adjusted by leach factors to account for the amount of the metal
dissolved, and therefore, bioavailable. These dissolved metals remain in the part of the plume that
is diluted in the water column instead of settling to the seafloor with the larger solids. This
resulting exposure concentration of SBF pollutants characterizes only the area within the discharge
plume. Within the mixing zone, however, the water column also contains "uncontaminated"
waters. Thus, for the exposure of finfish within the 100-m mixing zone, the effective exposure
concentration is the exposure concentration adjusted by the volumetric proportion of the total
water column that contains the discharge plume. This volumetric proportion represents the
proportion of time that exposure would occur assuming the fish have an equal probability of being
present (and therefore exposed) anywhere in the entire cylinder that makes up the mixing zone.
This proportion is determined in the following manner:
exposure proportion = discharge plume volume/water column volume
= discharge rate (mVmin) * tT (time to reach 100 m;
where:
discharge rate = 25.1 nrVday (= 0.0175 mVmin)
tT =100 m/current speed (m/sec)
r ' = 100m
h = depth affected by the plume, which = fall velocity * tT;
where fall velocity = 0.015 m/sec (Delvigne, 1996).
The effective exposure concentration of each pollutant is multiplied by this exposure
proportion and by a pollutant-specific bioconcentration factor (BCF) to yield the tissue
concentration of each pollutant in finfish on a mg/kg basis. Pollutant-specific BCFs used for this
analysis are presented in Exhibit 5-1. These calculated tissue concentrations represent a potential
upper estimate of contamination for fish contained within a 100-m radius of a discharge of SBF-
-------
5-3
Exhibit 5-1. Pollutant-Specific Bioconcentration Factors
Pollutant
Naphthalene
Fluorene
Phenanthrene
Phenol
Cadmium
Mercury-
Antimony
Arsenic
Beryllium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Aluminum
BCFfl/kg) (a)
426
30
2,630
1.4
64
5,500
1
44
19
16
36
49
47
4.8
0.5
116
47
231
(a) There are no BCFs for specific SBF compounds.
Source: Offshore Environmental Assessment (Avanti, 1993)
cuttings. The following sections provide the geographic region-specific input parameters for the
tissue concentration calculations. The calculations and resulting finfish tissue pollutant
concentrations are presented in Appendix 5-2 for the Gulf of Mexico and Appendix 5-3 for Cook
Inlet, Alaska.
5.2.1 Gulf of Mexico
The transport time for discharges in the Gulf of Mexico is based on a 15 cm/sec current
speed (MMS, 1989), resulting in an 11 minute estimation for the plume to reach 100 meters. The
time intervals used for the average dilutions within the mixing zone and the extracted base fluid
concentration data .from Brandsma (1996) are presented in Exhibit 5-2. The tissue concentrations
are presented in Appendix 5-2 for baseline and the discharge options.
5.2.2 Cook Inlet, Alaska
The transport time for discharges hi Cook Inlet, Alaska is based on a 40 cm/sec current
speed (EPA Region 10, 1984), resulting in a 4.2 minute estimation for the plume to reach 100
-------
5-4
Exhibit 5-2. Calculation of Average Dilutions within Gulf of Mexico Mixing Zone
Time (t; min.)
Base fluid concentration
@t(mg/l)
Initial base fluid content in
cuttings (mg/1)
Calculated Dilutions
1
76.7
3
17.4
5
8.7
7
5.5
9
4.0
11
3.0
112,750
1,470
6,477
12,90
9
20,33
1
28,54
3
37,425
Avg.
17,859
Source: From data provided for Figure 2, Brandsma (1996).
meters. The time intervals used to calculate the average dilutions within the mixing zone and the
extracted OBF concentration data from Brandsma (1996) are presented in Exhibit 5-3.
The calculations for determining the finfish tissue concentrations including the calculations
of the proportion of the plume impacting Cook Inlet, Alaska mixing zones are presented in
Appendix 5-3 for the discharge options. Current practice in Cook Inlet, Alaska is zero discharge
of SBF-cuttings so baseline impacts are zero and were not modeled.
5.3 Commercial Fisheries Shrimp Tissue Concentrations
EPA based projected shrimp tissue concentrations of pollutants from SBF discharges on
the uptake of pollutants from sediment pore water. The pore water pollutant concentrations are
based on the assumption of even distribution of the total annual SBF discharge over an area of
impact surrounding the model well. The area of impact was determined using the 11-well
synthetic fluid sediment concentration data described in section 4.3.1. For each distance from the
well, the corresponding sediment concentrations of synthetic base fluids were averaged and
plotted (see Exhibit 5-4).
Based on a log:log regression of these data, the distances to various concentrations of
synthetic base fluids were determined (i.e., order of magnitude sediment concentrations ranging
from 1 mg/kg to 100,000 mg/kg). A study by Berge (1996) observed the environmental effects
(fauna! changes) of treated OBF-cuttings on a natural seabed. Based upon the analyses provided in
Berge (1996), a no effect threshold was set at 100 mg/kg. The radial distance to that sediment
concentration (772 m as determined in Exhibit 5-4) results in an associated impact area of 1.9 km2,
which is used for the analyses presented in this section.
-------
5-5
Exhibit 5-3. Calculation of Average Dilutions within Cook Inlet, Alaska and Offshore
California Mixing Zones
Time (t; min.)
Base fluid concentration
@t(mg/l)
Initial base fluid concentration
in cuttings (mg/1)
Calculated Dilutions
Alaska (4.2 minutes)
1
76.7
2
30.1
3
17.4
4
11.8
5
8.7
112,750
1,470
3,747
6,477
9,551
12,909
Avg.
5,311
Source: From data provided for Figure 2, Brandsma.(1996).
While Berge indicates the usage of a 1,000 mg/kg threshold can be determined from data in
the study, the analyses are confounded by the statistical necessity of combining the data set into
low and high synthetic base fluid content groupings for the analyses. The low synthetic base fluid
content group was composed of cuttings treatments that resulted in residual base fluid levels of
150 mg/kg and 990 mg/kg. Thus, Berge also offers mat the no effect concentration found in the
experiments ranged from 150 ppm to 1,000 ppm of base fluid in sediment. For this analyses,
therefore, a no effect threshold of 100 mg/kg is used.
In order to calculate the discharge pollutant distribution over the 1.9 km2 impact area, the
following assumptions that were applicable in the Environmental Assessment for the offshore
effluent guidelines are used for this current SBF assessment (Avanti Corporation, 1993):
• Sediment depth affected = 5 cm
• Unit volume sediment affected = 0.0503?
• Density of sediment = 710 kg/m3
Mass of unit volume sediment = 35.5 kg
• Volume of water in unit volume of sediment = 32.5 liters
• Impact radius = 772 m; impact area = 1.9 km2
• Sediment mass = (impact area * sed. depth * sediment density) =
1.9 x 106 m2 * 0.05 m * 710 kg/m3 = 6.745e+07 kg
Average pollutant concentration (mg poll. / kg sed.) = poll, loadings / sed. mass
• Shrimp tissue concentration = (avg. poll, cone.) * (leach factor or partition coeff."1) *
35.5 kg sediment/32.5 1 water * (BCF) * (% lipids).
-------
5-6
Exhibit 5-4. Arithmetically-Averaged Concentration Data
. Field-collected data
1000
Radial Distance from Discharge (m)
100000
Regression Output:
XCoefficient(s) -1.5267
StdEirofCoef: 0.350
Constant: 14.7567
StdErrofYEst: 1.350
R Squared: 0.679
No. of observations: 11
Degrees of freedom: 9
Regression Equation: x(m) y(mg/l)
y=1.5267*x+14.7567 ('distance') (cone.)
Impact
Area
8
171
772
3,490
15,768
38
100,000
1,000
100
10
1
10,000
0.0002
0.004
0.1
1.9
38
781
The above assumptions are used to calculate the average pollutant concentrations in pore
water at any point within the well impact area. The calculations of these sediment pollutant
concentrations for Gulf of Mexico SBF-cuttings discharges are presented in Appendix 5-4. To
obtain the pollutant concentrations in shrimp tissue, the pore water concentration is multiplied by a
pollutant-specific BCF, and is adjusted for a shrimp lipid content of 1.1% (Avanti Corporation,
1993). The bioconcentration factors used in the current analysis are listed in Exhibit 5-1. The
following sections (5.3.1 through 5.3.3) present the input parameters for calculating the shrimp
tissue pollutant concentration for Gulf of Mexico under the BPT baseline and for all the
-------
. 5-7
geographic areas (Gulf of Mexico and offshore California) under each of the discharge options.
The shrimp tissue concentrations do not serve as endpoints for this analysis, but rather are used for
estimating the health risks presented in section 5.5 of this chapter. The results of the analysis for
Offshore California are presented in Appendix 5-1.
5.3.1 Gulf of Mexico
The concentrations of pollutants in shrimp tissue are presented in Appendix 5-4 for Gulf of
Mexico model wells under BPT baseline and the two controlled discharge options. Only shallow
water wells are considered for shrimp impact analysis because shrimp are harvested mainly from
waters potentially affected by drilling discharges from shallow water development and
exploratory model wells.
5.3.2 Cook Inlet, Alaska
Shrimp harvesting by trawling or pot fishing by any fishermen, including subsistence and
Native Americans is prohibited in Cook Inlet, Alaska by the Alaska Board of Fisheries due to
inadequate information regarding the biology and stock status of shrimp in Cook Inlet waters
(Beverage, 1998). This ban includes Native Americans as well Emergency Orders (AK Rule 2-S-
H-l 1-96 and AK Rule 5 AAC 31.390; AK Dept. of Fish & Game, 1998) were issued for Inner
Cook Inlet and Outer Cook Inlet in 1996 and 1997, respectively. A previous rule prohibiting
shrimp harvesting in Inner Cook Inlet dates back to 1988. There is currently no evidence that these
orders will be lifted in the near future. Therefore, human health effects from exposure to
commercial shrimp harvests were not analyzed for Cook Inlet, Alaska SBF-cuttihgs discharges.
5.4 Noncarcinogenic and Carcinogenic Risk - Recreational Fisheries
The concentration of pollutants in finfish tissue is used to calculate the risk of
noncarcinogenic and carcinogenic (arsenic only) risk from ingestion of recreationally-caught fish.
For this analysis, the 99th percentile intake rate of 189.9 g/day (uncooked basis) for consumption
offish caught in Cook Inlet, Alaska and 139.3 g/day for fish caught in either California or the Gulf
of Mexico are used as the exposure for high-end seafood consumers in the general adult population
(Tudor, 2000). This analysis is a worst case scenario because the seafood consumed is assumed
to consist only of contaminated finfish.
For noncarcinogenic risk evaluation, the tissue pollutant concentration (mg/kg) is
multiplied by the consumption rate (mg/kg/day) for a 70 kg individual. This value is compared to
the oral reference dose (RfD) to determine the hazard quotient (HQ) for each pollutant hi
accordance with the following equations:
-------
5-8
HQ = CDI/RfD
where
HQ = hazard quotient (unitless)
GDI = chrome daily intake (mg/kg/day)
RfD = reference dose (mg/kg/day)
and
GDI =(IR*TPC)/BW
where
IR = intake rate (0.177 kg/day)
TPC = tissue pollutant concentration (mg/kg)
BW = body weight (70 kg)
The RfD is based on the assumption that thresholds exist for certain toxic effects to occur. These
thresholds are estimates of a daily exposure to humans that is likely to be without an appreciable
risk of deleterious effects during a lifetime. Therefore, if the hazard quotient is less than or equal
to one, toxic effects are considered unlikely to occur. The oral RfDs used in this analysis are from
EPA's Integrated Risk Information System (IRIS) database (EPA, 1998c) and are summarized in
Exhibit 5-5. For those pollutants without a published oral RfD, no hazard quotient is calculated.
To calculate the carcinogenic risks, the slope factor as provided by IRIS is used to
estimate the lifetime excess cancer risk that could occur from ingestion of contaminated seafood.
The cancer risks are calculated in accordance with the following equations:
CR = GDI * SF
where
and
CR = cancer risk (unitless)
GDI = chronic daily intake (mg/kg/day)
SF = slope factor (mg/kg/day)'1
GDI =(IR*TPC*EF*ED)/(BW*AT)
-------
5-9
Exhibit 5-5. Oral Reference Doses and Slope Factors
Pollutant
Napththalene
Fluorene
Phenol
Cadmium „
Mercury
Antimony
Arsenic
Chromium
Nickel
Selenium
Silver
Thallium
Zinc
Barium
OralRfD
(mg/kg-day)
2.00e-02
4.00e-02
6-OOe-Ol
l.OOe-03
3.00e-04
4.00e-04
3.00e-04
3.00e-03
2.00e-02
5.00e-03
5.00e-03
8.00e-05
3.00e-01
7.00e-02
Slope Factor
(mg/kg-day)-1 (a)
NA
NA
NA
NA
NA
NA
l.SOe+00
NA
NA
NA
NA
NA
NA
. NA
(a) NA indicates that a slope factor is not available for that pollutant; there are no slope factors for
specific SBF compounds.
Source: EPA, 1998b; Integrated Risk Information System (IRIS).
where
IR = intake rate (0.1393 kg/day used in the Gulf of Mexico and offshore
California analyses and 0.1899 kg/day for the Cook Inlet, Alaska
analysis)
TPC = tissue pollutant concentration (mg/kg)
EF = exposure frequency (365 days/yr)
ED = exposure duration (two exposure durations considered in this analysis:
30 years and 70 years)
BW = body weight (70 kg)
AT = averaging time (70 year lifetime * 365 days/yr)
For this analysis, only arsenic has a slope factor available for estimation of the lifetime excess
cancer risk. The risk calculations for arsenic are performed considering a 30-year exposure
period and a 70-year exposure period. For the purposes of this analysis, a risk level of 1 x 10"6 is
considered to be acceptable.
-------
5-10
Exhibit 5-6 presents a summary of the health risks from ingestion of recreationally-caught
finfish from around SBF-cuttings discharges under current technology and the discharge option.
Current practice in Cook Inlet, Alaska and offshore California is zero discharge of SBF-cuttings,
so there health risks are zero for these geographic areas (California analysis is presented in
Appendix 5-1). For Cook Inlet discharge options and Gulf of Mexico baseline and discharge
options, none of the hazard quotients exceed 1. Therefore, toxic effects are not predicted to occur.
Also, all of the lifetime excess cancer risks are less than 10"6 and are, therefore, acceptable.
5.4.1 Gulf of Mexico
The noncarcinogenic and carcinogenic health risks for Gulf of Mexico recreational
fisheries are presented in Appendix 5-2 for baseline and the two controlled discharge options.
Based on the 99th percentile consumption rate, the hazard quotients for noncarcinogenic risks and
the lifetime excess cancer risk estimates for carcinogens (arsenic) are well below the acceptable
risk levels adopted by the Agency for this analysis.
5.4.2 Cook Inlet, Alaska
The noncarcinogenic and carcinogenic health risks for Cook Inlet, Alaska recreational
fisheries are presented in Appendix 5-3 for the discharge options. Because current practice in
Cook Inlet, Alaska is zero discharge of SBF-cuttings and there are no human health impacts, the
baseline is not presented . Based on the 99th percentile consumption rate, the hazard quotients for
noncarcinogenic risks and the lifetime excess cancer risk estimate for carcinogens (arsenic) are
well below the acceptable risk levels adopted by the Agency for this analysis under the two
controlled discharge options.
5.5 Noncarcinogenic and Carcinogenic Risk - Commercial Shrimp
To calculate the noncarcinogenic and carcinogenic health risks for commercial shrimp, the
methodology is the same as that used for recreational finfish. However, instead of calculating an
effective exposure concentration that describes the portion of the water affected within the mixing
zone, the exposure is adjusted by the amount of the total commercial shrimp catch affected. This is
estimated by prorating the total potential exposure (total catch) by the portion of the total shrimp
catch affected by the well type being analyzed. The shrimp catch is assumed to occur evenly over
the area occupied by the species harvested. As calculated for the offshore effluent guidelines
Environmental Assessment, the total catch is divided by the populated area to yield a catch density
in Ibs/mi2 (Avanti Corporation, 1993). This catch density is multiplied by the area affected for
each model well under current technology and the discharge
-------
5-11
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5-12
option (number of wells * 1.9 km2) and divided by the total catch to calculate a percent of the catch
affected by the SBF- cuttings discharge. Only shallow water model wells are used in this
assessment due to the limited shrimp harvesting that occurs hi water depths greater than 1,000 feet.
Exhibit 5-7 presents a summary of the health risks from ingestion of commercially-caught
shrimp. Details of the calculations of these risks are found in Appendix 5-4. None of the hazard
quotients exceed 1. Therefore, toxic effects are not predicted to occur. Also all of the lifetime
excess cancer risks are less than 10~6 and are, therefore, acceptable.
5.5.1 Gulf of Mexico
Under baseline, there are 91 development wells (86 existing and 5 new source) and 51
existing exploratory wells in Gulf of Mexico shallow waters (< 1,000 ft). Under the discharge
options, there are 132 (124 existing and 8 new source) development wells and 74 exploratory
wells in Gulf of Mexico shallow waters. The catch impacted in the Gulf of Mexico is calculated
in Exhibit 5-8.
These percentages of catch affected are used to adjust the intake calculations assuming that
individuals would consume seafood from the entire Gulf harvest and exposure would be
proportional to the amount of the total catch affected. Details of the estimated noncarcinogenic and
carcinogenic risks are presented in Appendix 5-4 for Gulf of Mexico commercial shrimp affected
by the current technology and the discharge options. Based on the 99th percentile consumption rate
of 139.3 g/day, the hazard quotients for noncarcinogenic risks and the lifetime excess cancer risk
estimate for carcinogens (arsenic) are well below the acceptable risk levels adopted by the
Agency for this analysis (see Exhibit 5-7).
5.5.2 Cook Inlet, Alaska
As presented in Section 5.3.2, shrimp harvesting by trawling or pot fishing is prohibited in
Cook Inlet, Alaska by the Alaska Board of Fisheries due to inadequate information regarding the
biology and stock status of shrimp in Cook Inlet waters (Beverage, 1998). Therefore, human
health effects from exposure to commercial shrimp harvests were not analyzed for Cook Inlet,
Alaska SBF-cuttings discharges.
-------
5-13
Exhibit 5-7. Summary of Shrimp Health Risks
Pollutant
Gulf of Mexico
Development
Baseline
BAT
Option 1
BAT
Option 2
Exploratory
Baseline
BAT
Option 1
BAT
Option 2
99th Percentile Hazard Quotient (a)
Naphthalene
Fluorene
Phenol
Cadmium
Mercury
Antimony
Arsenic
Chromium
Nickel
Selenium
Silver
Thallium
Zinc
5.82e-07
5.72e-09
3.20e-ll
3.54e-07
1.51e-06
8.47e-08
2.38e-07
1.99e-06
6.24e-08
6.28e-09
4.16e-10
1.03e-06
5.89e-09
2.86e-07
2.81e-09
1.576-11
1.74e-07
7.41e-07
4.16e-08
1.17e-07
9.77e-07
3.06e-08
3.08e-09
2.04e-10
5.08e-06
2.89e-09
2.63e-07
2.58e-09
1.44e-ll
1.60e-07
6.81e-07
3.82e-08
1.07e-07
8.98e-07
2.81e-0'8
2.83e-09
1.88e-10
4.67e-06
2.66e-09
6.84e-07
6.72e-09
3.76e-ll
4.16e-07
1.77e-06
9.95e-08
2.80e-07
2.34e-06
7.33e-08
7.37e-09
4.89e-10
1.21e-05
6.92e-09
3.36e-07
3.30e-09
1.85e-ll
2.04e-07
8.71e-07
4.89e-08
1.37e-07
1.15e-06
3.60e-08
3.63e-09
2.40e-10
5.97e-06
3.38e-07
3.09e-07
3.04e-09
1.706-11
1.88e-07
8.01e-07
4.50e-08
1.26e-07
1.06e-06
3.31e-08
3.33e-09
2.21e-10
5.49e-06
3.13e-09
Lifetime Excess Cancer Risk (b)
Arsenic
30-yr
exposure
70-yr
exposure
2.04e-ll
4.76e-ll
l.OOe-11
2.34e-ll
9.21e-12
2.15e-ll
2.40e-ll
5.596-11
1.18e-ll
2.75e-ll
1.08e-ll
2.53e-l 1
(a) Only pollutants for which there is an oral RfD are presented in this summary table.
-------
5-14
Exhibit 5-8. Calculation of Shrimp Catch Impacted in the Gulf of Mexico
Number of Wells
Area Impacted (km2)
(1.9km2/well)
Catch Rate (lbs/mi2) (a)
Total Catch Affected
(Ibs)
Total Catch (Ibs)
% of Total Catch
Affected
Baseline
Development
91
172.9
Exploratory
51
96.9
BAT Discharge Options
Development
132
250.8
Exploratory
74
140.6
10,850
724,310
405,932
1,050,648
588,999
165,604,330
0.437%
0.245%
0.634%
0.356%
(a)
The catch rate calculation is presented in Appendix A.
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6-1
6. TOXICITY
6.1 Introduction
This chapter presents information EPA has reviewed concerning the determination of
toxicity to the receiving environment of various synthetic base fluids and the formulated synthetic-
based drilling fluids (SBFs). This information includes data generated for toxicity requirements
imposed on North Sea operators as well as experimental testing conducted by the oil and gas
industry in the United States. Because the synthetic base fluids are water insoluble and the SBFs
do not disperse in water as water-based drilling fluids (WBFs) do, but rather tend to sink to the
bottom with little dispersion, most research has focused on determining toxicity in the sedimentary
phase as opposed to the aqueous phase.
Since 1984, EPA has used an aqueous phase toxicity test to demonstrate compliance with
NPDES permits for the discharge of drilling fluids and drill cuttings. This aqueous phase test
measures toxicity of the suspended particulate phase (SPP), and is often called the SPP toxicity
test (see "Drilling Fluid Toxicity Test" 40 CFR 435, Subpart A, Appendix 2). SBFs have
routinely been tested using the SPP toxicity test and found to have low toxicity (Candler et al,
1997). Rabke et al. (1998a), have recently presented data from an interlaboratory variability study
indicating that the SPP toxicity results are highly variable when applied to SBFs, with a coefficient
of variation of 65.1 percent. Variability reportedly depended on such things as mixing times and
the shape and size of the SPP preparation containers. As part of the coastal effluent guidelines
effort, published in December 1996, EPA identified the problems with applying the SPP toxicity
test to SBFs due to the insolubility of the SBFs in water (EPA, 1996).
North Sea testing protocols require monitoring the toxicity of fluids using a marine algae
(Skeletonema costatum), a marine copepod (Arcartia tonsd), and a sediment worker (Corophium
volutator or Abra alba). The algae and copepod tests are performed in the aqueous phase,
whereas the sediment worker test uses a sedimentary phase. Again, because the SBFs are
hydrophobic and do not disperse or dissolve in the aqueous phase, the algae and copepod tests are
only considered appropriate for the water soluble fraction of the SBFs, while the sediment worker
test is considered appropriate for the insoluble fraction of the SBFs (Vik et al., 1996a). As with
the aqueous phase algae and copepod tests, the SPP toxicity test mentioned above is only relevant
to the water soluble fraction of the SBFs (Candler et al., 1997).
Both industry and EPA identified the need for more appropriate toxicity test methods for
assessing the relative toxicities of various SBFs. EPA conducted a toxicity study that evaluated
the use of sediment testing with the amphipod Leptocheirus plumulosus as a test organism. The
study was also conducted to determine the toxicity of five base fluids and to determine the effects
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6-2
whole drilling fluid composition on the toxicity of a base fluid. Industry provided EPA with the
result of several additional studies in which tests were conducted to determine appropriate test
organisms;, to assess the use of formulated sediments as a dilution sediment; and to ascertain the
appropriate test duration for determination of discriminatory power between the toxicity of
individual base fluids and between the toxicity of individual base fluids as compared to the
toxicity of diesel. Industry provided over 50 bench reports from contract laboratories that support
an abbreviate acute test and assess the use of formulated sediment. Industry also submitted several
unpublished draft reports are not summarized in this EA because the tests did not meet acceptable
testing requirements and comprised primarily range-finding data.
Final data presented by industry and EPA have shown that the abbreviated acute toxicity
test of 96 hours increases the discriminatory power between the toxicity of individual SBFs and
between the toxicity of SBFs and diesel. Both EPA and industry data have indicated that esters are
the least toxic followed by IO, LAO and paraffins. These data also indicate toxicity for all base
fluids tested and variability within individual tests both increase with increased test duration.
Industry data indicate that a suitable 100%-formulated sediment for dilution sediment has yet to be
developed. The toxicity data on SBFs and SBF base fluids are summarized in Exhibit 6-1 and
Exhibit 6-2. In addition, each of the studies is summarized below.
6.2 Summaries of Reports Containing SBF-related Toxicity Information
The following two papers presented essentially the same data on Ampelisca abdita and
Corophuim volutator. However, Still and Candler (1997) presented additional data not included
by Candler et al., 1997. Therefore, we have included a summary of both papers.
Candler, J., R. Herbert and A.J.J. Leuterman. 1997. Effectiveness of a 10-day ASTM Amphipod
Sediment Test to Screen Drilling Mud Base Fluids for Benthic Toxicity. SPE 37890.
The authors reported the results of a study sponsored by M-I Drilling Fluids. The study
evaluated the use of the ASTM sediment toxicity test method E1367-92 for determining the toxicity
base fluids used for SBFs and OBFs. The base fluids tested were a diesel oil (DO), an enhanced
mineral oil (EMO), linear paraffin (LP), an internal olefin (IO) and a polyalphaolefin (PAO). The
tests were conducted with two marine amphipods, Ampelisca abdita and Corophium volutator.
The tests were conducted in two phases: 1) whole fluid was used to determine the range of toxicity
to A. abdita and 2) base fluid was used in definitive tests to determine 10-day LC50 values for
both test species. Chemical analyses for Total Petroleum Hydrocarbons (TPH) were used to
determine actual exposure concentrations of the highest concentration of each test. For Phase 1 of
the study, the amphipods were exposed to two concentrations (5,000 and 10,000 mg whole fluid/kg
dry sediment). Ranking for toxicity, from most toxic to least toxic, at 5000 mg/kg sediment was:
DO and EMO (zero percent survival in both tests), PAO (11 % survival), IO (32% survival), and
-------
- v.;:v.: 6-3
LP (44% survival). Rankings at the 10,000 mg/kg sediment level, from most to least toxic, was:
DO and EMO (O% survival), LP (8% survival), PAO (11% survival), and IO (25% survival).
For Phase 2, the amphipods were exposed to definitive concentrations of a DO, EMO, IO and
PAO. The toxicity ranking of the SBFs and OBFs were based on 10-day LC50 values. Those
LC50 values, presented in decreasing toxicity (increasing LC50 values) for A. abdita tests were:
EMO with an LC50 value of 557 mg/kg of sediment, DO with an LC50 value of 879 mg/kg, IO
with an LC50 value of 3,121 mg/kg, and PAO with an LC50 value of 10,690 mg/kg. The LC50
values for C. volutator were: DO (840 g/kg), EMO (7,146 mg/kg), IO (>30,000 mg/kg), and PAO
(>30,000 mg/kg). The authors stated that the study proved that the ASTM E1367-92 test methods
and both of the test species can be used as screening tool for use with synthetic base fluids.
Still, Land J. Candler. 1997. Benthic• ToxicityTesting of'Oil-Based andSynthetic-Based
Drilling Fluids. Eighth International Symposium on Toxicity Assessment. Perth,
Western Australia. 25-30 May'1997. ^_
A two phase sediment toxicity study was conducted to examine the applicability of
established sediment toxicity test methods for synthetic base fluids and SBFs. During Phase I, the
marine amphipod Ampelisca abdita was tested with one drilling fluid formulation dosed
individually with the following five base fluids: a diesel oil (DO), an enhanced mineral oil
(EMO), a linear paraffin (LP), an internal olefin (IO) and a polyalphaolefin (PAO). Testing during
Phase I served as rangefinders, with test concentrations of 5,000 and 10,000 mg drilling fluid/kg
dry sediment. Enhanced mineral oil and diesel were the most toxic for both concentrations. The
toxicity ranking (most toxic to least toxic) for the SBFs at 5,000 mg/kg were PAO, IO and LP. The
toxicity ranking (most toxic to least toxic) for the SBFs at 10,000 mg/kg were LP, PAO, and IO.
For Phase II, definitive sediment toxicity tests were conducted. LC50 values were determined for
EMO, DO, IO and PAO base fluids, using four marine amphipods: Ampelisca abdita, Corophium
volutator, Rhepoxynius abronius, andLeptocheirusplumulosus. For Ampelisca abdita, the
toxicity ranking (most toxic to least toxic) and corresponding LC50 values were: EMO (557
mg/kg); DO (879 mg/kg); IO (3,121 mg/kg); and PAO (10,680 mg/kg). For Corophium volutator,
the toxicity ranking (most toxic to least toxic) and corresponding LC50 values were: DO (840
mg/kg); EMO (7,146 mg/kg); IO (>30,OQO.mg/kg); and PAO (>30,000 mg/kg). For Rhepoxynius
abronius the toxicity ranking (most toxic to Jeast toxic) and corresponding LC50 values were: DO
(24 mg/kg); EMO (239 mg/kg); IO (299 mg/kg); and PAO (975 mg/kg). For Leptocheirus
plumulosus, the toxicity ranking (most toxic to
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6-7
Exhibit 6-2. Minimum and Maximum LC50 Values for New Sediment Toxicity Data Presented as
Comment Response on Either the Proposed Rule (12/99) or the Notice of Data Availability (4/00) for
Effluent Limitations Guidelines for the Oil and Gas Extraction Point Source Category.
Base Fluid
Diesel NSa
Diesel FSS
Ester NS
Ester FS
IONS
10 FS
Paraffin NS
LAONS
PAONS
PAOFS
Minimum and Maximum LC 50 Values (mg/kg)
96-h LC 50
Minimum
NA
776M
892"
703b,f
255"
450h
7686d
>12,800b-"
27,986"'"
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-
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Maximum
NA
1133"
374e
703"
21824"
6306C
>8000d
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37,035f
2624°
17,501"
5913h
—
—
292 ld
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Minimum
343b,=
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585e
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157"
495h
4275"
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2416"
1988e
2075f
<500b-c
626"
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205C
1065d
707b,e
333b,e
Maximum
NA
951e
635f
312
495h
10,219d
2501°
2530d
5270"
16,131f
1422°
-
1047°
1233b,r
407"
1207"
a natural sediment
b one data point reported
c reported by Commenter III.B.b.9 Public Comments PR
d EPA unpublished data
" Commenter A.a. 13 NODA
f Commenter A.a.30 NODA
g Formulated Sediment
k Commenter A.a.29 NODA
-------
6-8
least toxic) and corresponding LC50 values were: EMO (251 mg/kg); DO (850 mg/kg); IO (2,944
mg/kg); and PAO (9,636 mg/kg). These results were ranked against the UK Offshore Chemical
Notification Scheme (OCNS), which includes sediment testing as well as biodegradation and
bioaccumulation in the ranking procedure. Using the OCNS classification, the results of this study
ranked the based fluids, from most toxic to least toxic, as: diesel, enhanced mineral oil, IO and
PAO.
Rabke S. et al. 1998a. Interlaboratory Comparison of a 96-hour Mysidopsis bahia Bioassay
Using a Water Insoluble Synthetic-Based Drilling Fluid. Presented at 19th Annual
Meeting of Society of Environmental Toxicology and Chemistry. Charlotte, NC1998.
The authors conducted an interlaboratory variability study with six different laboratories
using the SPP toxicity test with a synthetic-based drilling fluid (SBF). The purpose was to
determine the variability associated with this test method when applied to SBFs. A subsample of
an internal olefin SBF was shipped to the individual laboratories where the SPP test was
conducted. Results were reported in ppm (vohvol) of SPP and ranged from 221,436 to
>1,000,000 ppm. The coefficient of variation was 65.1 %.
Rabke, S. andJ. Candler. 1998b. Development of Acute Benthic Toxicity Testing for
Monitoring Synthetic-Based Muds Discharged Offshore. Presented at IBC Conference on
Minimizing the Environmental Effects of Offshore Drilling, Houston Texas, February 9,
1998.
The authors used the ASTM E1367-92 method to determine the toxicity of synthetic-based
drilling fluids (SBFs) and oil-based drilling fluids (OBFs) to the marine amphipods Ampelisca
abdita andLeptocheimsplumulosus. The authors examined the variability of the test, including
variability due to test organisms. The authors used formulated sediments in place of natural
sediments to evaluate their use in marine sediment testing. However, concurrent tests were
conducted using natural sediment as a control. The test species were exposed to varying
concentrations of diesel oil (DO), polyalphaolefin (PAO) and internal olefin (IO). The authors
concluded that using formulated sediments and whole fluids decreased the usefulness of the test
method as a screening tool; PAO synthetic-based drilling fluids appeared to be as toxic as diesel
in the whole fluid/formulated sediment test; and formulated sediment gave acceptable control
survival although it reduced the discriminatory power of the tests. The results of the study are
presented in Exhibit 6-1.
Jones, F. V., J.H. Rushing ondM.A. Churan. 1991. The Chronic Toxicity of Mineral Oil-Wet
and Synthetic-Wet Cuttings on an Estuarine Fish, Fundulus grandis. SPE 23497.
The authors determined the toxic effects of cuttings associated with a mineral oil-based
drilling fluid (OBF-cuttings) and a poly alpha oelfin (PAO) synthetic-based drilling fluid (PAO-
-------
6-9
SBF-cuttings) to an estuarine fish, the mud minnow, Fundulus grandis. Unaltered cuttings were
dried and crumbled to a uniform state and divided in half. The cuttings were then hot rolled with
the appropriate amounts of each drilling fluid to obtain concentrations of 1%, 5%, and 8.4% oil
on wet cuttings, based on retort measurements. Before distributing the fish in test containers, the
fish were anesthetized with 2.5 ppt quinaldine, then measured for weight and length. The fish were
allowed to recover in fresh seawater before placement in test containers. Contaminated cuttings
were layered (approximately 3.8 cm thick) into tanks, then covered with seawater. Each tank
received seawater flow at a rate of 28.5 ml/2 minute intervals. The fish were exposed for a total
of 30 days. Fish were randomly removed from each tank on Day 15 for length and weight
measurements. The authors also sacrificed the fish for bioaccumulation measurements; no data
were provided in this paper. (However, see Chapter 7 for a discussion of Rushing et al., 1991, a
companion paper containing procedural details.) At Day 30 the remaining fish were measured for
weight and length. The authors concluded that neither the mineral oil-based nor synthetic-based
drilling fluids affected growth of the fish based on percentage growth. However, the overall
growth of the control and 5% PAO-SBF cuttings-exposed fish at Day 15 and Day 30 were
significantly greater than fish exposed to all other treatments.
Vik, E.A., S. Dempsey, B. Nesgard. 1996a. Evaluation of Available Test Results from
Environmental Studies of Synthetic Based Drilling Muds. OLF Project, Acceptance
Criteria for Drilling Fluids. Aquateam Report No. 96-010.
The authors provided a summary for tests conducted with unused base fluids and whole
SBFs. However, the authors did not cite sources for the data, leaving one to assume the work was
conducted by their laboratory. The authors state that the North Sea test organisms were a marine
algae (Skeletonema costatum), a marine copepod (Acartia tonsa), and a sediment worker
(Corophium volutator, orAbra alba). The authors consider that algae and copepods are relevant
for the water soluble fraction tests and sediment workers are relevant for testing the non-soluble
fraction. The authors further state that the algae has been the most sensitive of three species in
controlling the toxicity of discharged fluids.
Hood, C. 1997. Unpublished Data Received By J. Daly, EPA. July 9,1997 from
C. Hood, Baker Hughes INTEQ.
f
Unpublished data was provided prior to the proposal by Ms. Cheryl Hood of Baker Hughes
INTEQ, on the toxicity of four synthetic-based drilling fluids (SBFs) to the mysid, Mysidopsis
bahia and the amphipod, Leptocheirusplumulosus. The 96-h LC50 for the mysids ranged from
14,600 to >500,000 ppm SPP and the 10-d LC50 for the amphipod ranged from 943 to 4498 mg
SBF/kg dry sediment.
Hood, C.A., Baker Hughes. 2000. Letter to K. Ditthavong, EPA transmitting copies of toxicity
reports. 3/7/00. Attachments. (RecordNo. III.B.b.8)
-------
6-10
Thirty-one sediment toxicity tests were conducted with synthetic base fluids and the
amphipod Leptocheirusplumulosus. The studies were conducted to increase the data base on
sediment toxicity of selected SBFs using the 10 day acute toxicity tests with base fluids and
amphipods and to experiment with the use of formulated sediment as a diluent sediment. As a
result of the initial tests, abbreviated acute tests with base fluids and amphipods were conducted
for a duration of 96 hours. This abbreviated acute test has been used by industry in an attempt to
decrease in the variability in existing 10-day tests as well as increased discriminatory power
between toxicity of individual base fluids and toxicity of the base fluids compared to the toxicity
of diesel fluid.
Of the 31 different tests submitted, 12 of these tests report both 96-hour and 10-day test
results. Of the 31 tests submitted, 25 were conducted with five different lOs as the base fluid.
Within these five lOs, replicate testing was conducted to compare results from formulated
sediment tests to results from natural sediment tests as well as to examine the inherent variability
of whole sediment testing with SBFs. The testing to examine the variability was conducted with
natural sediment The results show that for all of the abbreviated acute tests, the formulated
sediment testing generated a lower LC50 values (more toxic) than the tests conducted with natural
sediment In two of the three tests where the formulated sediment tests were continued out to the
standard 10-day exposure, the results between formulated and natural sediment tighten to less than
a 2-fold difference between the LC50 values. Results of repeat testing were within standard ultra-
laboratory variability of 2-fold between LC50 values. Results from the 10-day exposure period
compared to the abbreviated acute tests indicate that the base fluids became more toxic to the
amphipods with time with LC50 values for the 96-hour tests up to as much 13 times as great as for
the 10-day test Using the discriminatory power between base fluids and diesel (LC 50 of base
fiuid/LC50 of diesel), the data indicated up to a 3 fold increase in toxicity, as related to diesel,
from the 96-hour tests to the 10-day tests (Exhibit 6-3). The discriminatory power results between
diesel and base fluids with tests conducted with formulated and natural sediment show an increase
in toxicity for tests conducted with formulated sediment. These discriminatory power data for the
formulated sediment tests ranged from 3.2 to 6.0 (higher the value the greater the difference) and
from 6.5 to 7.0 for the natural sediment tests. Discriminatory power results between base fluids
(LC 50 of best performing base/LC 50 of other base fluids) indicate that the 96-hour tests results in
LC 50 values closer together than the tests carried out to 10 days. These intra-base fluid
discriminatory power for the 96-hour tests ranged from 1.1 to 1.7 and for the 10-day tests ranged
from 2.2 to 4.1.
API/NOIA. 2000.Moran, Robert, National Ocean Industries Association, Re: National Ocean
Industries Association, American Petroleum Institute, Offshore Operators Committee, and
Petroleum Equipment Suppliers Association Comments on "Effluent Limitations
Guidelines for Oil and Gas Extraction Point Source Category, " Proposed Rule 65 FR
-------
. . 6-11
21548 (April 21, 2000). 6/20/00. Attachment: 18 Sediment Toxicity Reports, 6/15/00.
(Record No. IV.A.a. 13)
These 19 sediment toxicity tests were conducted with the amphipod Leptocheirus
plumulosus and provide both comparative abbreviated acute (96-hour) and 10-day data as well as
comparative formulated sediment (FS) and natural sediment (NS) data. These data were generated
for 4 base fluids, IO, ester, PAO and diesel. Of these 19 tests, only one set of FS/NS tests were
conducted with the PAO, with the remaining tests conducted with the diesel and IO. Results from
these tests demonstrate that the FS tests generate a lower LC50 than the tests conducted with NS, in
all cases. The maximum difference between FS and NS tests was 4-fold and was seen in tests
with both diesel and IO base fluids. This trend continued in the 10-day test as well. The 96-hour
and 10-day tests indicate that the lethality of the base fluid to the amphipod continued throughout
the exposure period; the 10-day LC50 values were as much as 11 times lower than the
corresponding 96-hour LC50 values. Although the control survival of the amphipods in the FS
was well within acceptable limits, the usefulness of this type of sediment is limited because of
material availability and quality as well as the need for 10% addition of natural sediment into the
formula. Discriminatory power for all base fluids as compared to diesel indicated greater
differences between diesel and base fluid toxicity for the 96-hour tests than the 10-day tests
(Exhibit 6-3). The discriminatory values for the 96-hour tests ranged from 2.7 for the PAO tests to
88 for the ester tests. The discriminatory power the 10-day tests ranged from 1 for the PAO to 11
for the ester. In most cases the discriminatory power for the formulated sediment tests was higher
than the discriminatory power for the discriminatory tests for the sediment test (Exhibit 6-3).
Comparisons of discriminatory power between base fluids indicated a ranking of toxicity from
least toxic to most as Ester, IO, and PAO (Exhibit 6-4).
Candler, John, M-I L.L.C., Effluent Limitations Guidelines for the Oil and Gas Extraction Point
Source Category; Addendum 1. 6/29/00. Attachment 6: Environmental Lab Report:
Benthic Toxicity Evaluation Using L. plumulosus
These bench data reports are from 13 sediment toxicity tests conducted with two base fluids,
an IO and diesel, and the amphipod Leptocheirus plumulosus. These tests were conducted with
formulated sediment and generated LC50 values using only the abbreviated 96-hour exposure
period. The 96-hour LC50 values for the IO ranged from 2,289 mg base fluid /kg dry sediment to
5,913 mg/kg. The 96-hour LC50 values for the diesel ranged from 450-703 mg/kg. The range of
results for both groups of tests were within the acceptable confines for intra-laboratory variability.
Stillmeado-w, Inc. and Environmental Enterprises, USA, Inc. BPA Leptocheirus plumulosus
toxicity test results. (RecordNo. IV.A.a.30)
This document provided results from concurrent 96-hour and 10-day sediment toxicity tests
conducted with three types of synthetic base fluids and the amphipod Leptocheirus plumulosus.
-------
6-12
As with the previous reported test results, the 96-hour LC50 values were consistently higher, as
much as 3 times higher, as the 10-day LC50 values, indicating increasing toxicity of the base fluids
to the amphipods over time. Discriminatory power analysis indicated a greater differences
between diesel toxicity and base fluid for the 96-hour tests than the 10-day tests (Exhibit 6-3).
Ditthavong, K., EPA. 2000. Data EPA Research Project. Files Emailed to R. Montgomery,
Avanti Corporation. 6/15/00. (Record No. IV.F.ll)
EPA conducted a research project to determine the toxicity of five base fluids and evaluated
the effect of whole drilling fluid composition on the toxicity of three of the five base fluids. The
five base fluids tested were an IO, an LAO, two esters, and a parafin. EPA also used the IO, one
of the esters, and the LAO as the base fluids for the whole drilling fluid study. The EPA study also
evaluated interlaboratory variability by conducting concurrent tests at the EPA Research Lab in
Gulf Breeze, Florida and a contract laboratory in Sequim, Washington. EPA also evaluated the
abbreviated acute test (96-hour exposure) by conducting these 96-hour tests concurrently with the
10-day tests. As with other studies presented in this document, the results ranked the toxicity of the
base fluids from least to most toxic as esters-IO-LAO-parafin.
In all but one case the 96-hour tests indicated less toxicity than the 10-day tests. In most
cases the results between EPA and the contract laboratories were within the standard 3-fold
interlaboratory variability. Because of reporting techniques of the whole drilling fluid study,
actual effects of whole drilling fluid composition on the toxicity of the base fluid were difficult to
determine other than to rank the fluids from least to most toxic. As with the base fluids this ranking
was ester-IO-LAO. The whole fluid test evaluated only the ester and IO to the longer 10-day
period. Again the ester was the least toxic as compared to the IO. Discriminatory power analysis
between base fluid and diesel toxicity indicated greater differences for the 10-day tests as
compared to the 96-hour tests. Discriminatory power analysis between base fluids indicated a
toxicity ranking of ester, IO, and LAO, from least to most toxicity.
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6-15
6.3 Summary
Since the original EA for the proposed SBF guidelines, both EPA and industry have
conducted studies to evaluate the sediment toxicity of SBFs. Industry's initial attempt to examine
different test organisms yielded a series of range-finder data that lead to the use of the amphipod
Leptocheirus plumulosus as the primary test organism. Industry also examined the use of
formulated sediments. Results of testing formulated sediments and estuarine organisms appeared
to be more difficult than expected and industry, although continuing research on the issue, has
suspended further testing with formulated sediments. Both EPA and industry's data have lead to
the following assumptions on the toxicity of SBF.
The ranking for the SBF toxicity from least toxic to most is esters-IOs-LAOs-P AOs-
paraffins.
Although formulated sediments appear to indicate more discriminatory power between
individual base fluids, control mortality continues to be a problem with 100% formulated
sediments. ;
The abbreviated acute test of 96 hours increases discriminatory power between individual
SBFs, however they are not to true measure of SBF toxicity. -
The toxicity of SBFs appear to increase with time (in comparison of a 96-hour exposure to a
10-day exposure).
-------
-------
7-1
7. BIOACCUMULATION
7.1 Introduction
One factor considered in assessing the potential environmental impacts of discharged
drilling fluids and drill cuttings is their potential for bioaccumulation. This chapter presents
information concerning the bioaccumulation of oleaginous base fluids, including the synthetic base
fluids and mineral oil.
The information that EPA identified was provided by oil and gas operators and by oilfield
chemical (drilling mud) suppliers. Much of this information is in the public domain. However,
only a minimal amount can be found in peer reviewed publications. Most of the available
information has been developed by mud suppliers to provide information to government regulators
to assess the acceptability of these materials for discharge into the marine environment. In
response to EPA's request for additional data on the bioaccumulative potential of SBFs in the
Notice of Data Availability (21548 FR 65), EPA received a short review from the API/NOIA
Industry Consortium (Moran, 2000).
7.2 Summary of Data
The available information on the bioaccumulation potential of synthetic base fluids is scant,
comprising only a few studies on octanohwater partition coefficients (P0w) and three on tissue
uptake in experimental exposures [only one of which derived a bioconcentration factor (BCF)].
The Pow represents the ratio of a material that dissolves or disperses in octanol (the oil phase)
versus water. The Pow generally increases as a molecule becomes less polar (more hydrocarbon-
like). The available information on the bioaccumulation potential of synthetic base fluids covers
four types of synthetics: an ester (two studies), internal olefins (IO; four studies), and poly alpha
olefins (PAO; five studies). One study included a low toxicity mineral oil (LTMO) for
comparative purposes. This limitation with respect to the types of synthetic base fluids tested is
partially mitigated by the fact that these materials represent the more common of synthetic base
fluid types currently in use in drilling operations.
These limited data suggest that synthetic base fluids do not pose a serious bioaccumulation
potential. Despite this general conclusion, existing data cannot be considered sufficiently
extensive to be conclusive. This caution is specifically appropriate given the wide variety of
chemical characteristics resulting from marketing different formulations of synthetic fluids (i.e.,
carbon chain length or degree of unsaturation within a fluid type, or mixtures of different fluid
types). Additional data should be obtained both for the purpose of confirming what is known
about existing fluids and to ensure completeness and currency with new product development.
-------
7-2 •"
The data that EPA identified concerning the bioaccumulation potential of synthetic base
fluids are summarized in Exhibit 7-1. Nine reports provided original information. This
information consisted of Pow data (based on calculated or experimental data), dispersibility data,
or subchronic exposure of test organisms to yield data for calculating BCFs or assessing uptake.
log Pow values less than three or greater than seven would indicate that a test material is not likely
to bioaccumulate (Zavallos et al., 1996).
ForPAOs, the logPows reported were >10,11.19,11.9, 14.9,15.4, and 15.7 in the five
studies reviewed. The four studies of IDs that were reviewed reported log Pows of 8.57 (8.6) and
>9. The ester was reported to have a log Pow of 1.69 in the two reports hi which it was presented.
The LAO log Pow was cited as 7.82 and a log Pow of 15.4 was reported for an LTMO. The only
BCF reported was calculated for IDs; a value of 5.4 I/kg was determined. In 30-day exposures of
mud minnows (Fundulus grandis) to water equilibrated with a PAO- or LTMO-coated cuttings,
only the LTMO was reported to produce adverse effects and tissue uptake/occurrence. Growth
retardation was observed for the LTMO and LTMO was observed at detectable levels in 50% of
the muscle tissue samples examined (12 of 24) and most (19 of 24) of the gut samples examined.
The PAO was not found at detectable levels in any of the muscle tissue samples and occurred in
only one of twenty-four gut samples examined.
7.3 Summaries of Identified Reports Containing Bioaccumulation Information
Friedheim, J.E. et al. 1991. An Environmentally Superior Replacement for Mineral-Oil
Drilling Fluids. SPE 23062. Presented at the Offshore Europe Conference, Aberdeen,
September 3-6,1991.
Bioaccumulation studies were conducted on both the PAO-base fluid and the PAO-based
SBF. The calculated octanol/water partition coefficient for the PAO gives a log Pow of 15.4. The
authors concluded the PAO was not expected to bioaccumulate in aquatic species for a variety of
reasons. The authors base their projection on data that indicate gill uptake of xenobiotics
increases with increasing lipophilicity up to about a log Pow of 7, beyond which there exists an
inverse relationship between lipophilicity and bioconcentration. Thus, these authors believe that
there appears to be a cut-off point in water solubility (or lack thereof) beyond which compounds
cannot move past the aqueous diffusion layer present at the water/gill interface; a similar scenario
accounts for a decreased absorption of hydrophobic chemicals in fish intestine. Therefore,
Friedheim et al. concluded the physico-chemical properties of the PAO (i.e., low water solubility)
would prohibit it from passing freely into aquatic species and bioaccumulating. PAOs are highly
lipid soluble, and thus Friedheim et al. believe they are likely to be absorbed into the organic
fraction of the sediment or onto suspended organic solids in the aquatic environment. These
authors postulate that the PAO either would not be bioavailable (due to
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7-3
Exhibit 7-1. Bioaccumulation Data for Synthetic Fluids and Mineral Oil Muds
Type of Synthetic
Base Fluid or
LTMO
PAO
PAO
PAO
PAO
PAO
IO
IO
LAO
Ester
LTMO
various
IO
PAO
LTMO
PAO
LTMO
LAO
Parameter Determined
log Pow: 15.4 (calculated)
log Pow: >10 (calculated)
log Pow: 14.9 - 15.7 (measured)
log Pow: 1 1 .9 (measured)
log Pow: 11.19
logPow:>9
log Pow: 8.57
log Pow: 7.82
log Pow: 1.69
log Pow: 15.4
dispersibility: ranking =
ester> di-ether » detergent alkylate > PAO >
LTMO
10-day uptake; 20-day depuration exposure gave
logBCF: 5.37 (C16 forms); 5.38 (CIS forms)
Uptake: no measured uptake in tissues after 30-day
exposure; presence noted in 1 of 24 gut samples
Uptake: after 30-day exposure, detectable amounts
in 50% of tissues analyzed (12 of 24) and 19 of 24
gut samples examined
Subchronic effects: equal or better growth vs
controls
Subchronic effects: retarded growth vs controls
Mytilus edulis log BCF: 4.84
Reference
Friedheim etal., 1991
Leutermann, 1991
Schaanning, 1995
Zevallos etal., 1996
Moran, 2000
Environment & Resource
Technology, Ltd., 1994a
Zevallos et al., 1996;
Moran, 2000
Moran, 2000
Growcock et al., 1994;
Moran, 2000
Growcock et al., 1994
Growcock et al., 1994
Environment & Resource
Technology, Ltd., 1994b;
Moran, 2000
Rushing et al., 1991;
Moran, 2000
Rushing et al., 1991
Jones etal., 1991
Jones etal., 1991
Moran, 2000
Abbreviations: PAO: poly alpha olefin; IO: internal olefin; LAO: linear alpha olefin; LTMO: low toxicity
mineral oil
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7-4
sequestration by the sediment) or would not be able to pass through the gill (or intestine) due to the
molecular size of the "suspended particle," (which is likely referring to the adsorption of the PAO
to the suspended organic solids to which the authors referred earlier).
Leuterman, A.J.J. 1991. Environmental Considerations in M-I Product Development
Novasol/Novadril. M-I Drilling Fluids Co., January 15, 1991.
Although Novasol [a PAO] is highly lipid soluble, with a calculated octanol/water partition
coefficient (log P) of >10.0, it was not expected by this author to bioaccumulate in aquatic species.
Leuterman presented several reasons he considered well-documented. These reasons include the
following:
1. High molecular weight, low water soluble polymers are thought not to pass biological
membranes due to molecular volume considerations.
2. Highly lipophilic chemicals in aquatic systems are likely to absorb and partition into the
organic fraction, in this case the organic fractions of the drilling fluid. In this arrangement
the chemical constituent would not be bioavailable for absorption due to sequestration in
the drilling fluid and cuttings or would not be able to pass through the gill or intestine, if
ingested, due to the molecular size of the chemical constituent.
3. Gill uptake of xenobiotics increases with increasing lipophilicity up to about log P of 7.
Beyond this level there exists an inverse relationship between lipophilicity and
bioconcentration. Toxicokinetically this reduction apparently results from a decrease in the
magnitude of the uptake rate constant. There appears to exist a cut-off point in the water
solubility, i.e., the lack of, beyond which compounds cannot move past an aqueous diffusion
layer present at the water/gill interface. A similar scenario accounts for decreased
absorption of hydrophobic chemicals in fish intestines. Since transport into biological
membranes requires, in most cases, that the xenobiotic be available in a dissolved form, the
physico-chemical properties of Novasol, i.e., low water solubility, would prevent its
passage into aquatic species and thence bioaccumulate.
4. If the base fluid did pass into the aquatic species, aquatic animals have the ability to
metabolize xenobiotics through various enzyme systems located primarily in the intestine and
liver. Once metabolized, these metabolites are normally of a more water soluble form, i.e.,
hydroxylated products, and are eliminated from the organism and not accumulated.
To confirm the expected low bioavailability of Novasol, M-I conducted a thirty (30) day
bioaccumulation test using the mud minnow Fundulus grandis. This author states that preliminary
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7-5
results of this test reveal no detectable amount of the material, or its degradation products, in the
tissue or organs of the test animals. In fact, the test animals showed no ill effect, no deformities
and no reduced growth rates. No data are provided, however.
Friedheim, J.E. andR.M, Panternuehl. 1993. Superior Performance With Minimal
Environmental Impact: A Novel Nonaqueous Drilling Fluid. SPE/IADC 25753. presented
at the SPE/IADC Drilling Conference, Amsterdam, February 23-25, 1993.
Both an octanol/water partition coefficient determination and actual laboratory testing with
fish were discussed to describe the potential for bioaccumulation of the PAO system. The authors
cite earlier reports (Friedheim et al. 1991), in which the partition coefficient (log Pow) for the PAO
is 15.4. This high value along with the large molecular weight of the material led the authors to
conclude the PAO should not accumulate in aquatic life. These arguments are based on knowledge
of gill uptake of xenobiotics and absorption of hydrophobic chemicals in intestines offish. The
authors' conclusion is that the physico-chemical properties of the PAO would prohibit it from
passing freely into aquatic species and bioaccumulating. Also, previous laboratory
bioaccumulation test results (Rushing et al., 1991) using Fundulus grandis (mud minnow) were
cited to support the arguments presented above.
Schaanning, M. T. 1995a. Evaluation of Overall Marine Impact of the Novadril Mud Systems.
NIVA Report 0-95018.
The ICI Brixham Laboratory estimated that log Pow = 14.9-15.7 for a PAO product coded
AB-5243-SO. This product was, however, composed of 65% of a synthetic hydrocarbon having a
chain length of 22 carbon atoms (C22), 20% C32, and 15% C42 and C52 oligomers, neither of
which were predominant components of the Novasol I and Novasol II base fluids. Measured
coefficients of polyalphaolefins (oligomer composition not specified) exceeded the upper limit of
8.0 that could be determined by the applied HPLC-method.
Information on concentrations of Novasol PAO's in animal tissues from exposed organisms,
as noted by these authors, is rather scarce. The authors discuss a few results of a recent study of
fish sampled at a North Sea Novadril II well site that were cited in M-I information dated January,
1995. No taste or smell was found in any of the fish sampled. Neither did the concentration of
Novasol exceed the detection limit of 0.1 mg.kg-1 in any of the fish samples analyzed. No
information was provided by the authors as to where, when and how sampling was performed or
how many and which species were analyzed. The authors also present that analyses of commercial
fish species captured at the drilling sites is obviously of great public interest. Because of the lack
of control on exposure of the analyzed individuals to the test chemical, however, a field study
showing neither smell, taste nor detectable concentrations, was not considered to yield evidence
that the chemical has a low potential for bioaccumulation. Results of Rushing et al. (1991) were
also discussed in this report.
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7-6
Growcock, F.B., S.L. Andrews and T.P. Frederick. 1994. Physicochemical Properties of
Synthetic Drilling Fluids. IADC/SPE 27450. Presented at the IADC/SPE Drilling
Conference, Dallas, Texas, February 15-18, 1994.
The dispersibility (aqueous phase partitioning) of synthetic fluids in seawater was tested.
The dispersibility test consists of shaking equal volumes of seawater and synthetic fluid for 10
seconds followed by a 10 minute equilibration prior to sampling the seawater phase for organic
carbon analysis. The test gave the following trend among various synthetic base fluids:
Ester>Di-Ether»DetergentAlkylate>PAO>LTMO.
This trend was considered by the authors as qualitatively consistent with the trend in the
octanol/water partition coefficient, Pow, which ranges from log Pow = 1.69 for the ester to log Pow =
15.4 for the PAO and the LTMO (no data or sources cited). The authors concluded that it is
possible for a significant portion of the ester, and perhaps other synthetics as well, to disperse in
seawater.
Fcerevik, I. Undated. Discharges and regulations of synthetic drilling fluids on the Norwegian
Continental Shelf and summary of results from ecotoxicological testing and field surveys.
Norwegian Pollution Control Authority.
Laboratory testing shows that many of the chemicals in synthetic drilling fluids have a
potential for bioaccumulation. Specifically the olefin base fluids show log Pow values well above
7.0. The ester base fluids are unlikely to bioaccumulate, but several of the additives in ester based
drilling fluids show log Pow values above 5.0. The molecular weight for both base fluids and
additives in synthetic drilling fluids are typically below 600.
The author asserts that existing bioaccumulation tests are not relevant for surface active
substances that are commonly present in synthetic drilling fluids. Rather, bioaccumulation should
be expressed as the distribution between sediment and water (the sedimentrwater partition
coefficient, log Psw), not as now by the octanol and water coefficient (log Pow). The author states
that the potential for bioaccumulation is overestimated due to inadequate methods of calculation.
Because these fluids have such low aqueous solubilities, a concern has been noted mat Pow
data are less relevant than, perhaps, Psw data. This would provide some measure of the potential
for long-term leaching of these materials into sediment pore water with their subsequent
availability to benthic infauna and epifauna. This concern is valid, and these data may be worth
pursuing because the standard Pow and Psw protocols appear adequate to evaluate these fluids and
are relatively brief and inexpensive procedures. Also, standard experimental protocols for
measuring uptake in test species are available and would be useful for testing a subset of materials
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7-7
for which log Pow or Psw determinations have been performed to confirm bioaccumulation
potentials projected from Pow or Psw data.
Environment & Resource Technology. 1994a. Bioaccumulation Potential of ISO-TEQ Base
Fluid. ERT 94/209. Prepared for Baker Hughes INTEQ.
The bioaccumulation potential of ISO-TEQ base fluid, an internal olefin of chain length
from 16 to 18 carbon atoms (C16-C18), was evaluated. The bioaccumulation potential was
estimated by measuring the log octanol-water partition coefficient by HPLC following OECD 117
guidelines. Under the standard conditions described in the report, no elution of the test substance
occurred during a period of 6.5 hours. To enhance the elution of the test substance, it was re-
examined using 2-propanol:water. The absence of detectable HPLC peaks with the standard
system indicated that the log Pow value for ISO-TEQ base fluid was greater than the value for the
most lipophilic calibration standard, suggesting that the value would be greater than 9.
Environment & Resource Technology. 1994b. Bioconcentration Assessment Report,
Assessment of the bioconcentration factor (BCF) of ISO-TEQ base fluid in the blue mussel
Mytilus edulis. ERT 94/061. Prepared for Baker Hughes INTEQ.
The study was conducted in accordance with an SOP written to conform with OECD
guidelines 305 A-E for the determination of bioconcentration or bioaccumulation of chemicals
from the aqueous phase. Specimens of the blue mussel Mytilus edulis were exposed to saturated
aqueous concentrations of ISO-TEQ base fluid ( a predominantly C16-C18 internal olefin) under
flow-through conditions for ten days, and subsequently allowed to depurate in clean seawater for a
further 20 days. BCF values were calculated from uptake and depuration rates or each compound
group separately. The bioconcentration factors (BCF) were calculated from
• the ratio of tissue (lipid) concentration to water concentration of the major components of the
fluid at equilibrium (10 days), or if a steady-state was not achieved,
• the ratio of the uptake to depuration rate constants, calculated as defined in the SOP.
The test met all validity criteria, with the exception of exposure concentration control, which
varied more than specified as a consequence of the very low saturation concentrations of the test
substance components. The variation was not, however, of a magnitude sufficient to significantly
affect the estimated low BCF values. ISO-TEQ exhibited high rates of uptake and depuration, with
no detectable tissue residue. The equilibrium log BCF values (lipid weight basis) for the test
substances were estimated to be 5.37 for the C16 compounds and 5.38 for the C18 compounds.
After cessation of exposure, the test animals depurated their tissues to concentrations of test
compound to < 1 ug.g-1 (0.03% of peak value). Log BCF values were approximately half the
probable log Pow values (>8).
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7-8
Jones, F.V., Rushing, J.H., andM.A. Churan. 1991. The Chronic Toxicity of Mineral Oil-Wet
and Synthetic Liquid-Wet Cuttings on and Estuarine Fish, Fundulus grandis. SPE 23497.
Presented at the First International Conference on Health, Safety and Environment, The
Hague, The Netherlands, November 10-14, 1991.
Mud minnows (Fundulus grandis) were held in tanks of synthetic seawater (i.e., formulated
from a mixture of salts and substances that mimic natural seawater). Drilling fluids were prepared
using a 80/20 ratio of mineral oil/water for a 7.4 pounds per gallon (ppg) drilling fluid (MOBF)
and a 70/30 ratio of PAO/water for an 11.0 ppg drilling fluid (PAO-SBF). Both drilling fluids
were then hot-rolled for 16 hours at 66°C. Each drilling fluid was added to a container of dried
cuttings, hand-mixed, and hot-rolled for another 24 hours at 66°C. Laboratory bioaccumulation
tests showed that the presence of cuttings soaked in an 11.0 ppg 70/3 0 PAO-SBF system did not
affect the growth rate of this species. Rather, they showed equal or better weight gain and size
increase as compared to the control samples. Conversely, test runs using MOBF-soaked cuttings
showed a retarded growth rate with respect to the control. The authors also offered that fish
cultured with the mineral oil had to spend a large portion of their energy removing this
hydrocarbon from their blood stream, and that this energy drain may have caused the lower
observed growth in those fish in the MOBF tanks.
Zevallos, M.A., J. Candler, J.H. Wood and L.M. Reuter. 1996. Synthetic-Based Fluids Enhance
Environmental and Drilling Performance in Deep-water Locations. SPE 35329.
Presented at the SPE International Petroleum Conference & Exhibition of Mexico,
Villahermosa, Tabasco, Mexico, March 5-7, 1996.
Measurement of bioaccumulation of synthetic fluids can be estimated using the N-
octanol/water partition coefficient (Pow). Pow values less than three or greater than seven would
indicate that the test material will not bioaccumulate. Both the 11.19 Pow for PAO and 8.57 Pow for
IO indicate these synthetic materials would not bioaccumulate. Ranked by their Pow values, lOs
have a greater potential than PAOs to bioaccumulate.
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| . 7-9
Davies, J.M., D.R. Bedborough, R.A.A. Blackman, J.M. Addy, J.F. Appelbee, W.C. Grogan, J.G.
Parker and A. Whitehead. 1989. The Environmental Effect of Oil-based Mud Drilling in
the North Sea. In: Drilling Wastes, F.R. Engelhardt, J.P Ray andA.H. Gillam (eds).
Elsevier Applied Science, New York. Pp. 59-89
During 1985 and 1986, fish were caught from three areas in the North Sea close to oil and
gas exploration and production platforms and from areas outside the influence of drilling activity
as reference (control) samples. These operations had drilled many wells using OBM, including
both diesel oil- and mineral oil-based OEMs. Fish were tasted by a trained panel to determine the
presence of any oily taint in the flesh. A fish was deemed to be oil tainted if more than half the
panel detected an oily taint. Among cod, haddock, tusk, and dabs caught between 0.40 and 9.3 km
from oil platforms, only for dabs caught between 0.55 km and 0.86 km did more than half the panel
detect an oily taint.
Rushing, J.H., M.A. Churan, andF. V. Jones. 1991. Bioaccumulationfrom Mineral Oil-Wet and
Synthetic Liquid-Wet Cuttings in an Estuarine Fish, Fundulus grandis. SPE 23497.
Presented at the First International Conference on Health, Safety and Environment, The
Hague, The Netherlands, November 10-14, 1991.
The authors report an experimental study on uptake of low aromatic mineral oil (LTMO) and
Novasol PAO in tissue and gut samples from mud minnows (Fundulus grandis) exposed for 30
days to water equilibrated with contaminated cuttings at nominal concentrations of 1%, 5%, and
8.4% base fluid (i.e., PAO or mineral oil). Gut samples represented carefully excised internal
organs and connecting structures from the mouth to the anus. Muscle tissue samples were prepared
from fish whose heads, tails, skin, and viscera were removed, thus including finer bones in these
samples. Samples from each of the three dosings were taken seven times during the course of the
exposure (Days 3, 7, 10,15, 20,25, and 30) and again after a 4-day depuration period.
Among fish exposed to SBM-coated cuttings, analysis offish tissue and organs using GC/MS
measured no uptake of PAO hi samples offish tissue, and an accumulation of PAO was observed
in only one of 24 gut samples. By contrast, fish exposed to LTMO cuttings showed accumulations
of mineral oil in 19 of 24 fish gut samples and detectable amounts of mineral oil components in 12
of the 24 tissue samples analyzed. Both mineral oil and olefins were shown present in the water of
the aquaria throughout the exposure period.
The authors concluded that the contrast between the mineral oil and the polyalphaolefins was
a result of restricted uptake of the larger olefin molecules across gill and digestive structures. The
authors further assert that the high molecular weight and the structure of PAOs is a key factor in
limiting the amount of uptake by fish. Since PAOs are a complex, high molecular weight molecule,
fish could not uptake the material through its gill structure. One sampling showed a low amount of
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7-10
PAO in the gut analysis. It is possible this material was in the intestinal tract of the fish and had
not passed through the fish when sampled.
Moran, R. 2000. E-mail to Carey Johnston, USEPA, regarding "An Evaluation of the
Bioaccumulative Potential of Synthetic Drilling Fluids, " with attachment. August 2, 2000.
In response to the EPA request for data related to the potential of SBFs to bioaccumulate, the
API/NOIA Industry Consortium prepared a short review on the bioaccumulative potential of SBFs.
The evaluation provided a summary of log Pow and BCF data from industry, primarily mud
company, sources. The data is included in Exhibit 7-1 and indicates that the bioaccumulation
potential of SBFs is limited given their extremely low water solubility and consequently, their low
bioavailability.
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8-1
8. BIODEGRADATION
8.1 Introduction
A number of different and contrasting test methods have been used to predict the
biodegradability of synthetic base fluids deposited on offshore marine sediments. These method
variations have included: calculation of biochemical oxygen demand in inoculated freshwater
aqueous media versus uninoculated seawater aqueous media; determination of product (gases)
evolved versus the concentration of synthetic base fluid remaining at periodic test intervals;
varying initial concentrations of test material; aqueous versus sediment matrices; and within
sediment matrices, layering versus mixed sediment protocols.
In the field, the mechanisms observed from the deposition of SBF contaminated drill cuttings
involve the initial smothering of the benthic community followed by organic enrichment of the
sediment due to adherent drilling fluids. Organic enrichment causes oxygen depletion due to the
biodegradation of the discharged synthetic base fluids. This biodegradation results In
predominantly anoxic conditions in the sediment, with limited aerobic degradation processes
occurring at the sedimentwater column interface. Therefore, the biodegradation of deposited
drilling fluid will be an anaerobic process to a large degree. Standardized tests that utilize
aqueous media, while readily available and easily performed, may not adequately mimic the
environment in which the released synthetic base fluid is likely to be found and degraded. As a
result, alternative test methods have been developed that more closely simulate seabed conditions.
One method uses a deposition of synthetic base fluid on marine sediment and measures degradation
in a sediment matrix. Another method uses anaerobic conditions in aqueous media (Vik et al.,
1996b; Limia, 1996; Munro, 1997). Additional, efforts have been made to utilize an existing
aqueous standardized method to simulate seafloor anaerobic degradation (Candler et al., 2000).
In addition to biodegradation test method research, industry supplied EPA with information
regarding the potential toxicity of the theoretical intermediate products resulting from SBF
degradation. According to the industry report, most of the intermediates are not toxic and those
that may be considered "moderately toxic" are not likely to persist in sediments (Entrix, 2000).
8.2 Biodegradation Test Methods
A variety of test methods, each with characteristic limitations and qualifications, has been
used to assess the biodegradation of test materials. Slater et al. (1995) present a descriptive
comparison of the technical details of the Organization for Economic Co-operation and
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Development (OECD) 301-series test protocols, the Biochemical Oxygen Demand for Insoluble
Substance (BODIS) protocols, and seabed simulation test protocols.
The OECD 301-series tests are all aqueous freshwater tests that use an activated sewage
sludge inoculum. As an example of 301 protocols, the OECD 301D "Clean Bottle" test protocol is
briefly summarized in Exhibit 8-1. The 301A through 301F tests vary in the analytical endpoint
used to quantify oxygen demand, the concentration range of the test substance, and their design
suitability among poorly soluble, volatile, or adsorbing test substances. The drawbacks of using
these tests for synthetic base fluids are: the insolubility of synthetic base fluids in aqueous media,
the use of a freshwater matrix, the use of an aqueous matrix for the test, and the aerobic nature of
the test
Exhibit 8-1. OECD301D: 28-Day Closed Bottle Test
A solution of test substance (e.g., synthetic base fluid) is prepared in a mineral medium consisting, of
stock solutions of a) KH2PO4, K2HPO4, NazHPO^HjO, NH4C1; b) CaCl2; c) MgSO4-7H2O; and d)
FeCl3'6H2O. The test solution is poured into test bottles and inoculated with a small number of
micro-organisms derived from the secondary effluent of a domestic sewage treatment plant (or
laboratory-scale unit) or surface water. A parallel series of bottles containing inoculated blank
medium is prepared for reference measurements of oxygen uptake by the inoculum. The closed test
bottles are incubated in the dark at constant temperature for 28 days. Dissolved oxygen
measurements are taken via Winkler titration or oxygen electrode at time zero and weekly intervals;
more frequent intervals require more bottles. The percent degradation of the test substance is
calculated as the ratio of the biochemical oxygen demand of the test substance (in mg O2 uptake per
mg test substance) and the theoretical oxygen demand (or less accurately, the chemical oxygen
demand) of the test substance.
The OECD 306 methods change the matrix from a freshwater matrix to a seawater matrix,
and allow for two analytical variants. In one analytical variant, the incubation period increases
from 28 days to 60 days. The biggest difference between the OECD freshwater and seawater tests
is the presence of an activated sludge inoculum in freshwater tests versus the absence of an
inoculum in the seawater tests, which relies on endogenous marine microorganisms for
degradative capacity.
Two International Standards Organization (ISO) protocols, one for freshwater (BODIS/FW)
and one for seawater (BODIS/SW), also have been used to assess biodegradability of insoluble
test materials. The same characteristics as discussed for the OECD 301 methods regarding the
presence/absence of a sludge inoculum apply to these ISO protocols: the freshwater test uses
inoculum but the seawater test does not. Likewise, freshwater and seawater respirometric
methods, which rely on analytically different endpoints, can be characterized as similar to the 301-
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8-3
series tests. An ISO protocol for assessing freshwater anaerobic biodegradability is available
(see Exhibit 8-2 for a brief description). The protocol may more accurately assess real-world
conditions for a large portion of discharged synthetic base fluids. However, although this protocol
provides a quantification of anaerobic biodegradation, it still relies on an aqueous freshwater
matrix.
To address the issue of aqueous versus sediment matrices, two non-standard test protocols
have been developed. One, the "NIVA" protocol (Norwegian Institute for Water Research;
Schaanning, 1994), which is commonly referred to as the "simulated seabed study," relies on
layering of test material on the surface of the test sediment. The other is the "SOAEFD" test
protocol (Scottish Office, Agriculture Environment and Fisheries Department; Munro et al.,
1997b), which is commonly referred to as the "solid phase test," mixes the test material into the
test sediment prior to incubation (see Exhibits 8-3 and 8-4 for brief descriptions of the NIVA and
SOAEFD protocols). These laboratory protocols, to date, have assessed biodegradability of
synthetic fluids at experimental sediment levels (NTVA = 700 mg/kg to 18,000 mg/kg; SOAEFD =
100 mg/kg to 5,400 mg/kg) that are below or at the lower end of the range of sediment
concentrations of synthetic fluids measured in the field at two drill sites in the North Sea (up to
4,700 mg/kg and up to 100,000 mg/kg) and one drill site in the Gulf of Mexico (up to 134,000
mg/kg, or 13.4 percent).
Aerobic test conditions have been summarized by Vik et al. (1996b) and are presented in
Exhibit 8-5; a summary of laboratory and field biodegradation assessment procedures was
prepared by Vik at al. (1996b) and is presented in Exhibit 8-6.
In an attempt to bridge the gap between aqueous and sediment matrices, another test protocol
was developed using the ISO 117734 method to simulate marine anaerobic degradation, of SBF.
Candler et al. (2000) modified the ISO 11734 method to include a marine sediment, as a
replacement for the dilution media, to which the authors added SBF. The authors included, from
the ISO 117434 method, the measurement of gases to determine the plateau of degradation and
reduction of SBF carbon of each fluid.
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8-4
Exhibit 8-2. ISO 11734: "Water Quality-Evaluation of the "Ultimate" Anaerobic
Biodegradability of Organic Compounds in Digested Sludge—Method by Measurement
of the Biogas Production"
A test compound (e.g., synthetic base fluid) is added to a dilution medium at an organic
carbon concentration of 20 mg/1 to 100 mg/1. The dilution medium is a solution of the following
constituents: KH2PO4, Na2HPO4-12H2O, NH4C1, CaCl2-2H2O, MgCl2-6H2O, FeCl2-4H2O,
Na2S'9H2O, resazurin (oxygen indicator), stock solution of trace elements, and de-oxygenated water.
Under anaerobic conditions, the test solution is inoculated with washed digested sludge containing
very low amounts of inorganic carbon, then incubated in sealed vessels in the dark at constant
temperature for 60 days. T
As a result of anaerobic degradation, carbon dioxide and methane evolve in the headspace
above the test solution, and the amount o£dissolved carbon dioxide, hydrogen carbonate, or
carbonate in the solution increases. The amount of microbiologically produced carbon in the head
space gas is calculated from the measured increase in head space pressure as applied to the gas law
equation (PV=nKT). The amount of inorganic carbon produced in the solution is measured, and is
added to the amount of head space carbon to determine the total carbon produced in excess over
blank values. The percentage biodegradation is calculated as the total carbon produced relative to the
initial carbon in the test compound. •--;V:
The progress of biodegradation can be charted by intermediate measurements of head space
pressure. A graph of pressure versus time should show an initial lag phase followed by a period of
steadily increasing pressure, ending with a plateau phase indicating the cessation of gas production.
Significant deviations from this course may indicate that the test should be prolonged or repeated.
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Exhibit 8-3. NIVA Protocol for Simulated Seabed Biodegradation Study
NIVA protocols have evolved since 1990, and intend to more accurately represent offshore seabed
conditions for biodegradation. The test consists of a series of chambers containing clean sediment, covered
with 15 cm of seawater drawn from a depth of 60 m from the Oslofjord and pumped through the experimental
chambers. On Day 0, a thin layer of drill cuttings (1 -2 mm) is created by adding a slurry to the chamber water
and allowing particulates and solids to settle. Tests run for as long as 160 days.
Based on the measured amounts of fluid at Day 0 and the last day of the test, the percentage decrease
is calculated. Rates are adjusted for the loss of drilling fluid due to seawater flow by using Ba concentrations
as an indicator for test substance lost due to seawater flow-through. NIVA has found that first-order kinetics
describe the loss of drilling fluid over time according to
Ct = C0xlO-kt
where C, =test substance concentration at time t (in days), C0 = the concentration at t = 0, k is the decay
constant, and t is the time in days.
Exhibit 8-4. SOAEFD Protocol for Solid-Phase Test System for Degradation of Synthetic
Base Fluid
A synthetic base fluid is homogeneously mixed at specific concentrations with prepared marine
sediment and maintained in a trough of flowing sea water for 120 days. Base fluid is added at concentrations
of 100 ppm, 500 ppm, and 5,000 ppm to represent historical measurements of mineral-oil-based cuttings
pile.s at distances from the platform of 1,000 m to 3,000 m, 200 m to 1,000 m, and 200 m, respectively. The
concentrations of added base fluid are determined empirically prior to the experiment as |ig TOC per g of dry
sediment.
At set times, triplicate jars are removed for chemical analysis of the base fluid. The concentration of
the base fluid remaining is determined by solvent extraction followed by gas chromatography with flame
ionization detection. Base fluid concentrations (in ppm) are graphed as a function of time; results are
compared in terms of how closely the data follow first order reaction kinetics, as expressed by the equation:
where AQ is the concentration of the substance at time t = 0, A, is the concentration at time t, k is the rate
constant for the reaction and e is the log to the base e.
Three additional analyses are conducted to further characterize the course of biological activity
throughout the experiment: the oxidation-reduction (redox) profiles of the test sediments as compared with
clean sediment; the number of cultivable bacteria from sediments; and the number of bacteria capable of
growth on the test fluid as the sole carbon source (the Sheen-screen). The sediment redox profiles, expressed
in mV, measure the level of oxygenation of the sediment at varying depths, indicating the local concentration
of organic matter. Trends in redox measurements are charted by depth and over time, for temporal and spacial
comparisons between test sediments and clean sediment. Throughout the experiment, samples are taken at the
sediment surface and at a depth of 4 mm to measure the number of "culturable" aerobic and anaerobic bacteria.
The Sheen-screen measures the number of aerobic and facultative anaerobic bacteria per gram of wet sediment
capable of growth on the synthetic base fluid as the sole carbon source. It is an indicator for the
biodegradation potential of a base fluid in the sediment used. The conditions for the Sheen-screen are aerobic
and thus, growth of obligate anaerobes is not provided for and test conditions do not accurately mimic real
-------
8-6
Exhibit 8-5. Summary of Aquatic Phase Aerobic Laboratory Biodegradation Test Conditions
and Then- Suitability for Poorly Soluble, Volatile, and Surface Active Compounds
OECD
Guidelines/
ISO Procedures
(a)
OECD 301A- DOC
Die-Away
OECD 301B - CO2
Evolution Test
OECD301C-
MITI (1) Test
OECD 301D -
Closed Bottle Test
OECD301E-
Modified OECD
Screening Test
OECD 301F -
Manometric
Respirometiy Test
OECD 308 -
Biodegradability in
seawater
-Shake Flask Test
-Closed Bottle Test
!SO-procedure:
3OD-test for
insoluble substances
(BODIS)
vfodified Seawater
BODIS Test
lespirometric
methods
Analytical
Method
Dissolved
organic carbon
(DOC)
CO2 evolution
Oxygen
consumption
Dissolved
oxygen
Dissolved
organic carbon
Oxygen
consumption
Dissolved
organic carbon
Dissolved
oxygen
Dissolved
oxygen
Dissolved
oxygen
Respirometric:
C02-
production
02-
consumption
in headspace
Suitability for compounds which
are:
Poorly
Soluble (b)
-
+
+
+/-
-
+
+/-
+
+
+
Volatile
-
-
+/-
+
-
+/-
+
-
-
+/-
Adsor-
bing (b)
+/-
+
+
+
+/-
+
+/-
. +
+/-
+/-
+
Concen-
tration of
Test
Substanc
e
10-40 mg
DOC/1
10-20 mg
DOC/1
lOOmg/1
2-5mg/l
10-40 mg
DOC/1
50-100 mg
ThOD/1
5-40 mg
DOC/1
2-10 mg/1
100 mg
ThOD/1
(c)
100 mg
ThOD/1
(c)
100 mg
ThOD/1
and
ower) . (c)
Ino-
culum
+
+
+ •
+
+
+
-
+
-
Test
Duration
(days)
28
28
28
28
28
28
60
28
28
28
Test
Mediu
m
FW
FW
FW
FW
FW
FW
SW
FW
SW
SW/FW
Abbreviations: ThOD = Theoretical oxygen demand; BOD = biochemical oxygen demand
(a) OECD (1993); ISO (1990)
(b) Characteristics of synthetic base fluids
(c) Corresponds to ~ 30 mg/1 test substance of drilling fluids
Source: Viketal, 1996b
_
-------
8-7
Exhibit 8-6. Summary of Test Procedures Used in the Biodegradation Testing of Synthetic-
Based Drilling Fluids
Factors
influencing test
results
Test Substance
Physical test
cond.:
Temperature °C
Availability of
oxygen
Nutrient availability
Test concentration
Depth of mud layer
Migration of test
substance
Inoculum:
Quantity/density
Variability
Acclimation
Source
Renewal
Sampling/analyses :
Sampling depth
Chemical analyses
Macrofaunal
analyses
Microbial analyses
Relevance of test
to real
environment
Aqueous Phase Tests
Aerobic
Seawater (a)
15-20
Good
Good
2-40 mg/1
NA
NA
Low ,
High
None
Seawater
None
Not relevant
Oxygen
demand/CO2
None
No
Aerobic
degradation
only
Freshwater
Anaerobic
Freshwater
Sediment/
Seawater
Base fluid or Synthetic Fluid
15-25
Good
Good
0.5-40 mg/1
NA
NA
Generally
high
Lower than
seawater
None
Activated
sludge
None
Not relevant
Oxygen
demand/CO2
None
No
Not relevant
37
None
Good
50 mg/1
NA
NA
High
Lower than
seawater
None
Activated
sludge
None
Not relevant
CO2
None
No
Not relevant
20
None
Good
5,000 mg/kg
Mixed into sed.
NA
Fairly low
High
Some
Seawater and
mixed sed.
None
Not relevant
CO2
None
No
Relevant for
anaerobic
degradation;
concentrations
are lower;
stable dosing
NTVA "Seabed
Simulation"
Cuttings
7-12
Lower
dependent on
test cone.
May be limiting
700-18,000
mg/kg
1-2 mm
Possible
Fairly low
High
Some
Seawater and
mixed sed. (b)
Possible
1-2 cm
Presence of
base
fluid/DO/pH/
redox
Mortality on
surface (d)
Yes
Relevant; test
concentrations
are lower;
question
anaerobic cond.
simulation and
test substance
migration
Phase Studies
SOAEFD
"Solid Phase"
Base fluid
7-12
Very low
May be limiting
100, 500, 5000
mg/kg
Mixed into sed.
Very low
Fairly low
High
Some
Seawater and
mixed sed. :
Possible
8.6 cm (c)
Presence of
base
fluid/DO/redox
None
Yes
Relevant; dosing
more stable but
misses layering
as in situ
(a) . No standard marine test presently exists and a large variety of methods have been used.
(b) In the latest NIVA test, natural benthic fauna were sieved out, then returned.
(c) NTVA are presently trying an alternative procedure using undisturbed sediments to keep the macro-fauna alive.
(d) Comprises the entire test container contents.
DO = dissolved oxygen; Adapted from Vik et al., 1996b
-------
8-8 ;
8.3 Biodegradability Results
This section discusses biodegradation results for both aqueous and sedimentary phase tests.
8.3.1 Aqueous Phase Tests
Exhibit 8-7 presents a ranking of aerobic biodegradation test results for an acetal synthetic
fluid using OECD 301B (FW), OECD (FW), 306 (SW), BODIS (FW), and BODIS (SW)
protocols at two concentrations of added test material. Given the substantial differences in
experimental design and protocols, results of 28-day tests expectantly show a wide range in
results, from 5% degradation to 86% degradation: Degradation was, as expected for a system
subject to saturation kinetics, more extensive for any given protocol at the lower test
concentrations (although with one exception). Few other comparisons are meaningful. For
example, seawater test show less degradation than freshwater tests. Thus, BODIS seawater tests
show less degradation (8% and 19.5% at 40 mg/1 and 10 mg/1, respectively) than BODIS
freshwater tests (50% and 86% at 40 mg/1 and 10 mg/1, respectively). Similarly, the OECD 306
seawater test at all concentrations shows less degradation compared to either the OECD 301B or
301D freshwater tests at the same concentrations. However, the freshwater tests all use an
activated sewage sludge inoculum of microorganisms, whereas the seawater tests are endogenous
levels of microorganisms, with no exogenous addition of microbial degraders. Because the initial
degradative capacity of the two types of media are not comparable, no valid quantitative
comparisons are possible. Exhibit 8-8 presents BODIS aerobic freshwater and seawater results at
one laboratory for two synthetic fluids (an ester and an acetal).
-------
8-9
Exhibit 8-7. Ranking of Aqueous Phase Biodegradation Methods and Test Results
No.
1
2
4
5
6
3
7
8
9
10
11
Test Method
BODIS Freshwater
OECD 301 B Freshwater
OECD 301 B Freshwater
BODIS Freshwater
OECD 306 Seawater
OECD 301 D Freshwater
OECD 301 D Freshwater
BODIS Seawater
OECD 306 Seawater
BODIS Seawater
OECD 306 Seawater
Test Concentration
10mg/l
10mg/l
20 mg/1
40 mg/1
0.5 mg/1
0.5 mg/1
2.5 mg/1
10 mg/1
10 mg/1
40 mg/1
2 - 2.5 mg/1
% Biodegradation
86
78.6
62.8
50
35
73
21
19.5
9.4
8
5
Source: Slater etal. (1995)
Exhibit 8-8. Average Percentage Biodegradation Using BODIS Seawater and Freshwater
Procedures for an Ester and Acetal
Base
fluid
Ester
Acetal
Seawater tests
Test#
(a)
1
2
3
4
5
6
Pooled
average
1
2
3
4
5
6
Pooled
average
Biodeg.
(%)
41
32
29
34
57
59
42
9
5
9
11
37
12
14
s.d.
(%)
(b)
8.1
2.9
7.1
3.7
5.2
5.0
12.9
2.2
1.2
1.8
2.8
4.7
7.1
11,2
Relative
s.d. (%)
(c)
18
9
24
11
9
8
31
24
24
20
25
13
59
80
n
5
5
5
5
5
5
3
0
5
5
5
5
5
5
3
0
Freshwater tests
Test#
(a)
1
2
3
4
Pooled
average
1
2
3
4 '
Pooled
average
Biodeg.
(%)
68
94
94
99
92
58
69
75
95
79
s.d.
(%)
(b)
3.1
11.2
9.9
1.9
12.9
10.7
9.1
12.0
4.9
16.5
Relative
s.d. (%)
(c)
5
12
11
2
14
18
13
16
5
21
n
4
4
7
10
25
4
5
7
10
26
(a) # = number of parallels
(b) s.d. = standard deviation
(c) relative s.d. = defined as (s.d./biodeg) x 100%
Source: Viketal.(1996b)
-------
8-10
Anaerobic biodegradation results are shown in Exhibit 8-9.
Exhibit 8-9. Anaerobic Biodegradability of Test Chemicals Examined in the ECETOC
Screening Test (a)
Test Chemical
fatty acid ester I
fatty acid ester II
Oleyl alcohol
2-Ethyl hexanol
Mineral oil A
Mineral oil B
Mineral oil C
Di-octyl ether
Di-hexadecyl ether
linear «-olefin (C1S/18)
linear «-olefin (C14)
Polyalphaolefin I
Polyalphaolefin II
Alkylbenzene
Acetal-derivative
Test
Duration
(days)
35
35
84
84
35
28
28
42
42
84
98
70
50
50
70
Degradation in the ECETOC test (% of organic carbon)
Net gas
Production
63.3
61.2
61.1
57.3
0.7
4.3
3.8
8.8
-0.6
22.3
40.5
4.4
-1.6
0.9
3.7
Net DIC (b)
Production
19.2
22.5
27.5
21.5
3.2
1.1
2.0
3.5
1.9
0.1
7.8
10.0
2.2
-2.4
8.9
Extent of Ultimate
Degradation (c)
82.5±13.9
83.7±13.1
88.6±14.8
78.8±21.4
3.9±11.0
5.4±8.2
5.8±6.7
12.3±10.8
1.4±12.5
22.4±19.5
48.3±15.5
14.4±20.3
0.6±16.2
-1.5±12.2
12.6±19.2
(a) ECETOC = European Centre for Ecotoxicology and Toxicology of Chemicals
(b) DIC = Dissolved Inorganic Carbon
(c) Value reported is mean value (from 5 replicates) and its 95%-confidence interval
Source: Steberetal. (1995)
8.3.2 Sedimentary Phase Tests
Schaanning (1994; 1995; 1996a; and 1996b) reported on a series of studies using the NIVA
methods (Exhibit 8-3) to compare the biodegradation rates (half-life) of ester, IO, LO,PAO and
ether base and based fluids. The results from the studies indicated the following degradation rates
-------
., ' 8-11
esters>LO>IO>PAO>ethers. The half-lifes reported were esters ranged from 16 to 22 days, LO
half-life reported was 51 days, IO half-life reported was 73 days, PAO ranged from 43 to 207
days, and the ethers ranged from 254 to 536 days.
Vik et al. (1996b) compare the results of two sedimentary phase protocols (NIVA and
SOAEFD) for ester-type synthetic fluids (Exhibit 8-10). An ester-type synthetic base fluid was
degraded 46% .and 97% at 28 days and 160 days, respectively, in the NIVA protocol, with a
calculated half-life of 31 days. The SOAEFD protocol for a similar synthetic base fluid resulted
in 97% degradation at 28 days with no further measured degradation at 60 days, giving a
calculated half-life of 12 days. Experimental differences, as discussed earlier, are substantial
enough that any comparison is not very meaningful. Vik et al. (1996b) also report results of the
NIVA protocol (see Exhibit 8-10) across a variety of synthetic fluids and mineral oil. Then-
results indicate the ester and LAO fluids (respective half-lives of 31 and 43 days) degrade more
rapidly than the PAO, acetal, and mineral oil (half-lives ranging from 199 - 207 days). This
general trend was also observed in the solid phase tests, at least for the lower test concentrations.
Limia (1997) reports solid phase degradation data for a series of test substances that
included an ester, acetal, PAO, IO, LAO, n-paraffin, and mineral oil. Results suggested relative
degradation rates were dependent on initial concentrations. At the highest concentration (5,000
mg/kg) the ester, LAO, and acetal all showed substantial degradation (25 - 50%;
ester>acetal>LAO) after 120 days, whereas all other base fluids tested showed little degradation.
At 500 mg/kg, degradation of the ester was nearly 60%, whereas all of the other base fluids
degraded much less. At 100 mg/kg, only the ester, LAO, IO, and n-paraffin all degraded
substantially (>75%), whereas the other test materials (mineral oil, PAO, and acetal) did not show
more than 35% degradation. Similarly, Munro et al. (1998) reported degradation rates using the
SOAEFD method that were highly concentration dependent as well as sediment dependent. The
half-life for all compounds tested (olive oil, mineral oil, ester, and PAO-LAO blend) increased
with concentration and from mud to sand.
To evaluate relevant conditions of base fluid degradation within the US boundaries, EPA
(Ditthavong, 2000) conducted a degradation study using the SOAEFD method with sediment from
Galveston Bay, Texas at a test temperature of 20°C. This study was conducted using test
concentrations of 1,000, 2,000, and 5,000 mg base fluid/kg of dry sediment and five base fluids:
an ester, IO, LAO, PAO, paraffin, plus positive and negative controls. The tests were run for a
total of 112 days, with chemical analyses conducted every 28 days. This EPA study resulted in a
degradation rate ranking of ester>LAO>IO>paraffin>PAO which is similar to the other studies
reported here. The EPA study indicated an inverse concentration-dependent degradation rate for
all base fluids. The higher the concentration of the base fluid the slower the base fluid degraded.
Percent degradation values for the EPA study are presented in Exhibit 8-11.
-------
8-12
Exhibit 8-10. Percentage Biodegradation of Base Fluids in Drilling Fluids Measured by
Various Test Methods
Drilling
Fluid/Base
Fluid
Tested
An ester
A mineral oil
APAO
Anacetal
AnIO
An LAO
AnLO
An ether
% Biodegradation Measured by Sedimentary Phase Test Methods
NIVA's Seabed Simulation Studies
(layered using drilling fluid)
160-day
97
44
43
39
93
28-day
46
23
11
12
38
Half-life (days)
(a)
16,20,22
399
43,127,207
200
73
43
51
254, 392, 536
SOAEDF's Solid-Phase Sediment Test
(base fluid/sand mixture)
60-day
67b, 97C, 98 (d)
98, 78, 25 (e)
16, 10, -4 (e)
-11,4,8(6)
20,0, 10 (e)
60, 10, -2 (e)
70,23,5(e)
28-day
97
Half-life
(days)
37 (b), 12 (c),
10 (d)
"
(a) Values from Schaanning (1994, 1995, 1996a & 1996b)
(b) Mixed in mud substrate; Munro et al. (1997)
(c) Substrate not specified in Vik et al. ( 1 996)
(d) Mixed in sand substrate; Munro et al. (1997)
(e) Three values presented are day 56 values at 100 mg/kg, 500 mg/kg, and 5,000 mg/kg sediment substrates,
respectively; Munro etal. (1997)
Source: Adapted from Vik et al. (1996b)
In further efforts to evaluate reproducibility of the SOAEFD method by laboratories in the
U.S., Candler et al. (1999) conducted a series of SOAEFD studies using Gulf of Mexico-relevant
conditions. The authors used estuarine sediments collected in Galveston Bay, Texas and
conducted the studies at 20°C and 25°C. These results were then compared with results of testing
conducted with a modification of the ISO 11734 anaerobic test. The modification to the ISO
method was primarily the use of marine sediments in place of an aqueous matrix as a
substrate for degradation. A comparative ranking of percent degradation was then used to evaluate
test methods. The authors also used the results to determine the method that demonstrated the
highest level of discriminatory power between individual base fluid degradation rates and
between SBF degradation compared to the degradation rate of mineral oil and diesel. The 25 °C
SOAEFD test produced results similar to the previously presented papers by Munro for esters
(90% degradation by Day 21); however results for the IO degradation were significantly reduced
to only 10% as compared to the reported 80% by Munro in the same time
-------
8-13
Exhibit 8-11. Percentage Biodegradation of Base Fluids Conducted by U.S. EPA Using the
SOAEFD Method.
Base Fluid
Tested mg/kg
Olive Oil
1000
2000
5000
Ester
1000
2000
5000
LAO
1000
2000
5000
IO
1000
2000
5000
Paraffin
1000
2000
5000
PAO
1000
2000
5000
Mineral Oil
1000
2000
5000
Percent (%) Reduction
Day 14
96
96
78
56
56
53
10
24
14
12 ,
8
12
17
17
16
8
10
2
9
7
15
Day 28
• _.
98
90
74
65
: 57
20
18
19
18
13
18
15
-..12
16
10
:-- 11
5
11
-.- 10
": 12
Day 56
—
99
—
85
72
68
17
16
11
26
21
27
2
-2
1
-6
-2
-6
3
3
2
Day 84
—
—
99
87
88
75
51
40
40
47
30
31
27
22
17
7
5
1
17
7
7 •
Day 112
—
99
92
86
69 - .
53
36
55
48
30
38
26
21
5
7
3
21
13
11
Source: Ditthavong, 2000.
period. By decreasing the test temperature to 20°C, which relates more closely the water
temperature of the Gulf of Mexico, the degradation rate of the ester was reduced to 80% in 35 days
and the IO degradation to 90% hi 140 days. Although the results varied on actual degradative
rates for the tests conducted at 20°C and 25°C, the degradation rate ranking of
ester>IO>MO>diesel remained similar previous data.
-------
8-14
Candler et al. (2000) reported that the use of the modified ISO method revealed similar
rankings as those of other SOAEFD tests. The modified ISO method used gas production as a
measurement of degradation and is, therefore, not directly comparable to the SOAEFD method.
The endpoint of degradation for this modified method is the plateau of gas production. Each base
fluid is then be ranked by the number of days to plateau. This ranking, after 16 tests conducted by
Candler et al. (2000), is ester>LAO>IO>PAO>paraffins. Candler et al. (2000) further reported a
standard lag phase in gas production for all base fluids of 30-70 days, using the ISO method. This
lag phase is consistent with the SOAEFD method conducted at 20°C. By comparing the
discriminatory power results from the SOAEFD and modified ISO tests, Candler et al. (2000) was
able to show a 2-fold increase in the discriminatory power between SBF degradation and the
negative control degradation using the ISO method. The percent degradation resulting from the
SOAEFD tests are presented in Exhibit 8-12.
8.4 Discussion and Conclusions
The result of this review is that the current state of knowledge for these materials is as
follows:
All synthetic fluids have high theoretical oxygen demands (ThODs) and are likely to produce
a substantial sediment oxygen demand when discharged hi the amounts typical of offshore
drilling operations.
Existing aqueous phase laboratory test protocols are incomparable and results are highly
variable for SBFs. Sedimentary phase tests are less variable in their results, although
experimental differences between the "simulated seabed" and "solid phase" protocols have
resulted in variations between test results.
Testing by industry and EPA, using existing sedimentary tests and the modified IOS 11734
test, have yielded similar degradation rate rankings of ester>LAO>IO>Paraffin>PAO. The
esters, LAOs, and lOs degrade two to three times faster than mineral and diesel oils.
There is disagreement among the scientific community as to whether slow or rapid
degradation of synthetic base fluids is preferable with respect to limiting environmental
damage and hastening recovery of benthic communities. Materials that biodegrade quickly
will deplete oxygen more rapidly than more slowly degrading materials. However, rapid
biodegradation also reduces the exposure period of aquatic organisms to materials which
may bioaccumulate or have toxic effects.
-------
8-15
Exhibit 8-12. Percentage Biodegradation of Base Fluids Conducted by Oil and Gas Industry
Using the SOAEFD Method.
Fluid
mg/kg
Olive Oil
120
500
Ester
120
500
IO
120
500
Diesel
120
500
Min. Oil
120
Percent Reduction
SOAEFD Method 25°C
Day?
80
NT
50
NT
10
NT
5
NT
10
Day 14
100
NT
100
NT
10
NT
5
NT
5
Day 35
NR
NT
NR
NT
20
NT
10
NT
,
50
SOAEFD Method 20°C
Day?
NT
80
NT
10
NT
0
NT
0
NT
Day 14
NT
90
NT
20
NT
NA
NT
NR
NT
Day 35
NT
90
NT
80
NT
20
NT
15
NT
Day 140
NT
NA
NT
NA
NT
90
NT
18
NT
NR = Not Reported
NT = Not Tested
Source: Candler et al 2000
Existing field data suggest these materials will be substantially degraded on a time scale of
one to a few years; however, the distribution and fate of these materials is not extensively
documented, especially as applicable to the Gulf of Mexico where only three field studies
have been conducted.
The existing data from field studies suggest that organic enrichment of the sediment will be a
dominant impact of SBF-cuttings discharges. Biodegradability of these materials is therefore an
important factor in assessing then: potential environmental fate and effects.
Available standard methods yield results that are highly variable across available
freshwater and seawater protocols. These methods (all aqueous, most freshwater, and all but one
aerobic) also are not very relevant to the conditions under which discharged materials will be
-------
8-16
found (i.e., a largely anoxic, marine sediment matrix). Nonetheless, one could try to identify tests
that still offer useful insight into the potential fate of these materials. Unfortunately, field data for
which potential correlations could be examined are too scant for meaningful quantitative analyses
to these standard laboratory methods.
Seabed simulation protocols and solid-phase tests have been developed to better represent
receiving water conditions. Still, the issue of layering versus sediment mixture of test substances
cannot be resolved absent better field data of actual initial deposition and longer term sediment
depth profiles of these materials in discharged cuttings. It seems likely the real world situation is
a mixture of the two.
Each of the existing biodegradation test methods has advantages and disadvantages. The
seabed simulations better represent field conditions, but they are expensive and have limited
market availability. The standard aqueous test methods are not relevant to field condition!?, but are
more rapid, more widely available, and less expensive. The solid phase test combines the benefits
of these two extremes: it mimics receiving water (sediment) conditions, is reproducible, and can
be made simplistic enough to perform at moderate expense.
-------
9-1
9. SEABED SURVEYS
9.1 Background
This chapter presents a summary of the seabed surveys conducted at sites where cuttings
contaminated with SBFs (SBF-cuttings) have been discharged. Because more surveys have been
performed and more detailed information has been collected at sites where WBFs (exclusively)
have been discharged, results from WBF sites are also presented for comparison. The technical
performance of SBFs is comparable to that of OBFs, and EPA is projecting that SBFs may be used
as a replacement to OBFs more so than as a replacement of WBFs. However, as far as
environmental effects of the discharge are concerned, EPA believes that SBFs are more
comparable to WBFs. Also, WBFs are currently allowed for discharge in certain offshore and
coastal areas, while OBFs (and OBF-cuttings) are not. For these reasons, EPA sees it fitting to
compare the environmental effects of SBF-cuttings discharge with those of WBF and WBF-cuttings
discharge.
The literature available to EPA for SBF discharge sites include studies performed in the
Gulf of Mexico and in the North Sea. These studies have been performed by regulatory bodies,
industry groups or individual companies. The results are available in either the open literature or
if submitted to EPA as public comments, in the rulemaking record. For WBF discharge sites, EPA
used the Offshore Proposed Effluent Guidelines Regulatory Impact Analysis (Technical Support
Document Vol. Ill; Avanti Corporation, 1993) as a source of information on field studies. This
volume contains extensive lists of case studies on environmental impacts from oil and gas effluent
discharges. Many of these studies were reviewed for information regarding seafloor and benthic
impacts of water-based fluids and associated cuttings. In addition to this volume, additional
citation searches for studies of the impacts of cuttings also were performed.
Materially, SBF wastes are different from WBF wastes in at least three important ways:
Only SBF-cuttings are discharged, with retention of the SBF base fluid generally ranging
between a low of 2 percent for the larger cuttings and a high of 20 percent for the smallest
cuttings (fines). On the contrary, with WBFs, in addition to the WBF-cuttings, large
volumes of WBF are also discharged. Thus, for an equal volume of hole drilled, the
volume of WBF-related discharge is expected to be much greater than the volume of SBF-
related discharge.
• WBFs contain very high levels of suspended and settleable solids (and are, in fact,
referred to as "muds" in the industry) that disperse in the water column and produce a
plume with many fine particles that settle rather slowly. Hence, they may be transported
large distances. SBF-cuttings, however, tend not to disperse in the water column nearly to
the same extent as WBFs because the particles are "oil" wet with the synthetic material.
-------
Even compared to WBF-cuttings, SBF-cuttings tend to be larger than WBF-cuttings. Again
the reason is that SBFs do not disperse the cuttings particles to the same extent as WBFs.
Because larger particles settle faster than smaller particles, SBF-cuttings tend to be
deposited in a smaller impact area than WBF-cuttings.
• SBF-cuttings have a significant organic component that is not present in WBFs, namely the
synthetic base fluid; The synthetic base fluid, in general, is insoluble in water and deposits
in the sediment with the cuttings. Thus, compared to WBFs, SBFs have an additional
pollutant factor to consider. The synthetic base fluid may have both direct and indirect
adverse effects. Direct effects include physical effects as well as chemical toxic effects to
benthic or epibenthic organisms. Indirect effects include both the effects on organisms that
feed on these benthic organisms and the effects of anoxic/hypoxic sediment conditions from
degradation of synthetic base fluids (due to their oxygen demand in local sediment). At the
same time, synthetic base fluid may have less effect on the water column due to their
insoluble characteristics.
These differences are important in making the comparison between SBF and WBF
discharges, as is presented in the following sections.
9.2 Assessment of Field Studies
9.2.1 Findings
A large number of field studies of environmental impacts of exploratory well drilling
discharges1 in several offshore locations provide sufficient information to arrive at reasonably
reliable findings for WBF seabed impacts. In contrast, existing data for SBFs are limited and do
not appear to be sufficient to reliably project potential impacts. The different SBF studies used
sampling designs that are incompatible and have methodological limitations (e.g., seasonal
variability issues) that reduce the analytic clarity. Further field research is required to adequately
characterize offshore impacts of synthetic-based fluid discharges.
Water-Based Fluids
The case studies reviewed by EPA characterize drilling fluids and cuttings dispersion,
sedimentation, impacts on the sediment and benthos, and some of the potential factors influencing
the magnitude of impacts. Exhibit 9-1 summarizes the major impacts of each of the reviewed
studies. This review suggests that these discharges are capable of producing localized impacts but
do not document larger-scale impacts. However, these studies are not sufficient to conclude that
regional-scale impacts are not occurring.
Studies of development operations are much more limited in both number and scope (e.g., there are no
pre- versus post-drilling surveys). Therefore, conclusions of impacts for WBFs are considerably more
uncertain for development drilling than for exploratory drilling.
-------
9-3
Field studies of drilling fluid discharge plumes indicate that, as a generalization, plume
dispersion is sufficient to minimize water quality impacts and water column toxicity concerns in
energetic, open marine waters, such as the domestic OCS.
In shallow water areas (e.g., less than 5-10 meters), field data on plume dispersion are
minimal., and are insufficient to conclude that water column effects present only a minor potential
concern. Some modeling data suggest water quality and toxicity parameters could be adversely
affected under shallow water conditions. Also, in water depths of less than 5 meters, the
reliability of most models that are suitable for application to drilling fluid discharges becomes
questionable. Thus, the potential water column impacts of those discharges hi shallow waters (<5
meter) is not known with any degree of confidence.
The degree of impact of drilling fluids and cuttings on benthic and demersal species is
highly dependent on a number of local environmental variables (e.g., depth, current and wave
regimes, substrate type) and on the nature and volume of the discharges, including cuttings size and
the location of the outfall in the water column. Impacts can be considered to fall into two
relatively distinct categories: short-term effects due to either toxicity or burial by drilling fluid
and/or cuttings; and longer-term effects due to chemical contamination or physical (textural)
alteration of the sediments.
For example, Cook Inlet and Tanner Bank sites are both characterized as having strong
currents. At these depths, currents significantly affect cuttings sedimentation patterns as well as
cuttings transport along the bottom, entrainment and reworking of the sediment. Under these
conditions, the investigators did not observe discrete cuttings piles which tend to form in more
quiescent locations (Ray and Meek, 1980; Houghton et al., 1980). In the Gulf of Mexico, cuttings
piles 150 m in diameter and 1 m in height have been reported (Zingula, 1975). On the other hand,
cuttings seemed to be present at relatively farther distances in more energetic locations (Houghton
etal., 1980; see below).
The extent of cuttings accumulation is important in assessing benthic impacts. A general
trend of impacts is that specimen abundance decreased closer to the well. Several studies cited
that the lowest numbers of organisms were at the 100 m stations, which were the closest stations to
the well in these studies. Even in the dynamic location of Cook Inlet, authors reported that number
of organisms and species diversity were significantly lower at the 100 m and 200 m
-------
9-4
Exhibit 9-1. Marine Studies of Water-Based Drilling Fluid Impacts
Study Source
Menzie et al.,
1980; Mariani et
al., 1980
Houghton et al.,
1980; Lees and
Houghton, 1980
Ray and Meek,
1980; Meek and
Ray, 1980
Zingula, 1975
USDOI, 1977
CSA, 1986
Boothe and
Presley, 1989
Study Site/
Location
NJ 18-3
Block 684
Mid-Atlantic
Continental Shelf
Cook Inlet
C.O.S.T.well
Alaska
Continental Shelf
Tanner Bank
California
Continental Shelf
South Timbalier
Block 172
Louisiana
Continental Shelf
Mustang Island
Block 792
Texas
Continental Shelf
East Breaks Area
Block 166
Gulf of Mexico
Northwest Gulf
of Mexico
Water
Depth (m)
120
62
63
33.5
36
76-160
30m;
100m
Impacts (a)
Sediment
• 21 fold increase in Ba at
1.6km .
• 3.6 fold increase in Pb at
200m
• 2.5 fold increase in Ni at
100m
• 4 fold increase in Vn at
100m
• increased percentages of clay
size particles within 1 .6 km
• cuttings piles observed
• cuttings (1.34 mm dia.) and
20% increase in sediment Ba
cone. 400 m north of platform;
• no piles
• most cuttings fell within 50
m, fine cuttings within 100 m -
200 m of the discharge source;
• mud on cuttings washed off
during settling;
• no piles
• below discharge point:
cuttings covered by normal
marine sediments 8.5 months
after drilling cessation
• cuttings observed at four 100
m and one 500 m station
• 2.5 fold increase in Ba during
drilling at 1,000m
• 7.5 fold increase in Ba and
60% increase in Cr at 4 km
• 2 fold increase in % Fe at
500m
• Ba increase within 500 m;
2.3-11 fold for all 6 sites
• Pb increase within 500 m;
3.8 fold for 1 site
• Hg increase within 250 m;
4-7 fold for 2 sites
Biota
• within 150m:
1 . burial of sessile mega-
benthos and
macrobenthos;
2. lowest values of
species diversity;
3. lower numbers of
species
• Ba increase in tissue at
1.6km:
mollusks: 20 fold
polychaetes: 40 fold
brittlestars: 133 fold
• substantial decrease in
number of organisms
from pre- to during and
post-drilling at both 100
m and 200 m
ND
• below discharge point:
same abundance of fauna
in cuttings samples as in
"normal" sea bottom at
8.5 months
• specimen abundance
significantly decreased
along 100 m periphery;
•effect to 1,000m
ND
ND
-------
9-5
Exhibit 9-1. Marine Studies of Water-Based Drilling Fluid Impacts (Continued)
Study Source
CSA, 1988
CSA, 1989
CSAandBany
Vittor & Assoc.,
1989a,b
Bothner etal.,
1985
Steinhauer et al.,
1990
Northern
Technical
Services, 1981
Study Site/
Location
Gainesville Area
Block 707
Florida
Continental Shelf
Pensacola Area
Block 996
Gulf of Mexico
Alabama State
Waters
Georges Bank
Block 3 12
Block 410
Atlantic
Continental Shelf
Santa Maria
Basin
California
Continental Shelf
Beaufort Sea
RISTWell
Alaska Coastal
Water
Depth (m) •
21
50-60
40-60
90-410
8
Impacts (a)
Sediment
• increase in Ba:Fe ratio:
90% at 4,000 m
• increase in Cr cone:
11% at 300m
• almost 3 fold increase in Ba
and Ba/Fe ratio at 2,000 m
• 2 to 5 fold increase in Ba at
1,000m
• 25% of barite deposited
within 6 km
• Ba transport detected at 35
km
• cuttings observed within 500
mat Block 3 12
• cuttings observed at 2 km
station at Block 410
ND
• cuttings accumulation
observed:
@ discharge pt: 5-6 cm
@ 3 m: 2-3 cm
@6m: 1-2 cm
@ 30 m: <0.5 cm
• elevated Co, Cu within 50 m
Biota
• absence of seagrass
within 300 m
• growth inhibited beyond
300m to 3.7 km.
• 77% decrease in
seagrass leaf count at 3.7
km
• burial of live bottom
communities at 25 m
• reduced bryozoan
coverage within 2,000 m
of discharge
• elevated As in oysters
behind barrier islands
ND
• sediment flux related to
decreased soft coral
coverage
• statistical power of
study limited to 70% or
greater
• decrease in number of
organisms 3 months after
discharge
ND = no data
(a) Results presented represent a range of time periods relative to active drilling. Some surveys were
conducted while drilling was ongoing; others took place many years after drilling ceased. For greater
detail than presented in this summary, please refer to the individual study summaries that follow.
-------
9-6 :
sampling points than the control location (Lees and Houghton, 1980). These local effects have
been ascribed to both physical changes in sediment texture and toxic effects. However, studies
have not been designed to discriminate between these two potential causative factors.
The Cook Inlet Continental Offshore Stratigraphic Test (COST) well study was the only
study reviewed that carefully analyzed sediment cores for the presence of cuttings as well as
conducted chemical analyses. Barium concentrations in the sediment were found to be elevated in
samples containing cuttings (defined by the authors as particles >0.85 mm) as far as 400 m from
the platform (Houghton et al., 1980). These analytical results suggest that some drilling fluid still
adheres to the cuttings and is transported and redistributed together with the cuttings. This is in
contrast to the study in which divers observed drilling fluid being washed from the cuttings as the
cuttings dropped through the water column within several meters of the outfall, although this latter
observation was visual in nature (Ray and Meek, 1980).
The most clearly documented point source effect of these discharges has been alterations in
sediment barium (Ba), a tracer for drilling fluids solids. Observations on sediment alterations
from field studies of both single-well and multiple-well facilities include:
• Increases in Ba levels of 2-fold to 100-fold above background at the drill site, with typical
values of 10-fold to 40-fold
Average measured background levels are reached, statistically, at 1,000-3,000 m; single
transect values have been elevated at up to 8,000 m
• Increases in Ba fall off logarithmically with distance from the drill site; regression
analyses indicate background levels are achieved at 2,000-20,000 m.
Increases in a suite of other trace metals associated with drilling fluids (As, Cd, Cr, Cu,
Hg, Pb, Zn) have also been observed. These increases:
Are of a lower magnitude than seen for Ba (generally not more than 5- to 10-fold above
background)
Are more spatially limited, when compared to background levels, than seen for Ba
(generally withing 250-500 m of the drill site, although increases at 1,000-2,000 m have
been noted) •
Are noted consistently as a group, but are variable for any specific metal among the
various studies.
Observations on the long-term, regional scale fate of drilling fluid solids indicate that the
materials may be very widely dispersed over large areas. Dispersion is related directly to bottom
energies of the receiving water (more shallow waters being more energetic than deeper waters).
-------
9-7
In shallow water (13-34 m) Boothe and Presley (1989) found that only about 6% of
discharged Ba was accounted for within a 3 km radius of three drill sites in northwestern
Gulf of Mexico; in contrast, for three drill sites in deeper waters (76-102 m) within the
same study, the authors found 47% to 84% of the discharged Ba was found within a 3 km
radius
At these same six sites, Ba concentrations 3 km from the drill sites ranged from 1.2 to 2.9
tunes predicted background at the shallow water sites and at the deep water sites ranged
from 2.0 to 4.3 times predicted background (Boothe and Presley, 1989)
Drilling fluid solids can be transported over long distances (35-65 km) to regional areas of
deposition, albeit at low concentrations, based on a study of eight wells (Bothner et al.,
1985).
Biological effects have routinely been detected at distances of 200 m to 500 m. Less routinely,
effects have been observed at greater distances (1-2 km). These effects more typically are found
to fall into one of two categories: those that are statistically significant at the level of individual
stations but cannot be integrated into an easily defined pattern or those that are not statistically
significant at the level of individual stations but do form significant correlations at larger levels of
integration. Specific observations are as follows:
The most affected community appears to be seagrass communities. Data on seagrasses are
limited to a single study, but it documented damage much more severe than in any other
study to date. Approximately 9 weeks after the drilling operation commenced, seagrasses
were completely absent within 300 m of the drill site; at a distance of 3.7 km from the drill
site, leaf biomass and leaf numbers showed only a 25% increase compared to the increases
shown at the reference station (CSA, 1988).
Fauna also have been affected, including changes in abundance, species richness (number
of species), and diversity. Taxa include annelids, mollusks, echinoderms, and crustaceans.
• Alterations to benthic community structure are virtually always observed within 300 m of
the drill site. However, changes have been noted in some cases at 500-1,000 m, and a few
reports indicate alterations have occurred at 1-2 km.
Changes have been ascribed to purely physical alteration in sediment texture and to
platform-associated structural effects (i.e., from the fouling community) more frequently
than to toxic effects. These causes are plausible, but there are not systematic studies of
their relative contribution to observed impacts. Also, alterations due to physical causes
may not be any less adverse than those due to toxic pollutants, and may be more persistent.
Bioaccumulation has been observed for a suite of metals (Ba, Cd, Cu, Hg, Ni, Pb, V), but
the magnitude of this effect is usually low (i.e., less than a factor of 5).
-------
SM5
Synthetic-Based Fluids
The extent of the literature on field studies of impacts from discharges of SBFs is more
limited than for impacts from discharges of WBFs. However, the number of studies has increased
significantly in the last few years. EPA has identified and reviewed 16 studies, totaling 28 sites,
for this environmental assessment. A summary of the results are provided in Exhibit 9-2. Other
survey sites, and additional surveys at some of the same sites also exist. However, difficulties
occurred in trying to review this additional information: some studies are only available in
Norwegian while others are proprietary or confidential in nature. The results of the studies
reviewed also present variability in terms of assessing the potential for adverse impacts from
SBFs. This limited and varied information base makes drawing any generally applicable
conclusions a difficult, and potentially unreliable, endeavor.
One study on the domestic continental shelf, hi 39 m of water in the Gulf of Mexico,
discharged a relatively small amount (354 bbl) of PAO SBF adhering to the drill cuttings (Candler
et al., 1995). At a maximum, this amount represents approximately 45 metric tons of discharged
olefins, which compares to North Sea discharges of approximately 100-1,155 metric tons of
synthetic base fluid at each of fifteen study sites. The top 2 cm of sediment were sampled at
stations only out to 200 m, with 2,000 m reference stations. Synthetic base fluids, as measured by
total petroleum hydrocarbons (TPH), showed substantial (60% - 98%) decreases between 'the first
and second sampling surveys (i.e., after 8 months) at all but the closest, 25-meter station. How
much of this decrease was due to biodegradation, as opposed to sediment redistribution and
reworking, is uncertain. Although the data are somewhat difficult to interpret, it appears that little
further reductions in TPH occurred between the second and third surveys (a 16-month period).
This finding for a PAO synthetic base fluid contrasts with North Sea data on ester- and ether-type
synthetic base fluids that indicate a continuing decrease in synthetic fluid over time. Limited
analysis of benthos (the third survey only) indicated significant differences in the diversity scores
at 25 m and 50 m stations compared to reference stations.
EPA received information on the on-going joint Industry/MMS GOM seabed survey. The
Indusfry/MMS workgroup completed the first two cruises of the four cruise study ha time for EPA's
consideration for the final rule. Cruise 1 was a physical survey of 10 GOM shelf locations, with
the objective of detection and delineation of cuttings piles using physical techniques. Cruise 2 was
to scout and screen the final 5 shelf and 3 deep water GOM wells chosen for the definitive
-------
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• 9-13
study where SBF were used. The SBF-cuttings discharges included either internal olefins or
LAO/ester blends. Both cruises did not detect any large mounds of cuttings under any of the
platforms. Remotely operated vehicles (ROV) using video cameras and side-scanning sonar were
used to conduct the physical investigations on the seabed. Video investigations only detected small
cuttings clumps (<6") around the base of some of the platforms and 1" thick cuttings
accumulations on platform horizontal cross members. Outside of a 50-100' radius from the
platform, no visible cuttings accumulations (large or small) were detected at any of the platform
survey sites.
For three North Sea study sites, EPA reviewed the impacts from the discharge of SBFs. At
a well site (K14-13) in the Dutch sector located at a depth of 30 m, approximately 180 metric tons
of ester SBF (resulting from the discharge of approximately 477 tons of adherent synthetic base
fluid) were discharged (Daan et al., 1996). Surveys occurred 1 month, 4 months, and 11 months
after SBF discharges ceased. The synthetic base fluid was detected in the upper 10 cm of
sediment to a distance of 200 m from the discharge site (which was the farthest distance sampled
in the second survey). During the second survey, sediment ester levels appeared to increase, a
phenomenon that the authors surmised was related to resuspension and transport of highly
contaminated and heterogeneous sediment very near the discharge becoming spread out and more
well-mixed over a larger area between surveys. Significant decreases of 65% to 99% in sediment
ester levels occurred, however, between the second (4 month) and third (11 month) surveys.
Effects on benthos were more extensive: for the second survey effects were noted at 500 m
stations, with much more pronounced effects within 200 m. Benthic analyses from the third survey
indicated significant effects occurred only to 200 m. Additionally, recolonization and recovery at
500 m to 3000 m stations were also noted as occurring within the study area after 11 months.
EPA reviewed results from a study of the discharge of 97 metric tons of an ester SBF in the
Norwegian sector (Ula well 7/12-9) in a water depth of 67 m (Schaanning, 1995). Surveys were
conducted immediately, one year, and two years after discharge ceased. Sediment ester levels fell
dramatically, with both maximum values and average values within 1,000 m decreasing more than
five orders of magnitude over the course of the study, and more than three orders of magnitude
between the first and second surveys. Benthic organisms were severely impacted out to 100 m in
the first survey (immediately) after discharge ceased. Two years after discharge ceased, the study
found an increase in the number of organisms but a decrease in the number of taxa.
EPA reviewed results from a study of the discharge of 160 metric tons of an ether SBF in
the Norwegian sector at the Gyda well site 2/1-9 that were presented in Schaanning (Bakke et al.,
1992; 1993 as cited in Schaanning, 1995). Schaanning reports results from three surveys, one in
1991,1992, and 1993. Ether levels seemed to fall continuously, with mean ether levels decreased
by factors of 2-fold and 10-fold for 1992 and 1993 compared to 1991. This degree of degradation
is considerably less than that reported above for the ester SBF at the Ula well site. Schaanning
-------
9-14
interpreted these results as indicating that a lag phase occurred in the biodegradation of the ether
base fluid. Benthos were analyzed only at four stations in 1993; no data were reported, although
Schaanning states that Bakke et al. (1992) observed "remarkably weak" effects.
There is very little information upon which to base any broad conclusions about the
potential extent of impacts from SBFs. It appears that biological impacts may range from as little
as 50 m to as much as 500 m shortly after discharges cease to as much as 200 m a year later. Ester
SBFs appear to be more readily biodegraded in North Sea studies than an ether SBF; the Gulf of
Mexico study suggests PAOs also are less biodegradable than esters. Also, although esters appear
to be readily biodegraded, one study indicates the persistence of uncharacterized "minor" impacts
on benthos after synthetic base fluid levels have fallen to reference levels. These limited data,
however, are not entirely adequate as a basis for any reliable projections concerning the potential
nature and extent of impacts from discharges of SBFs. However, the reported adverse benthic
community impacts occurring shortly after discharges cease, are expected, given the basic SBF and
marine sediment chemistry, the level of nutrient enrichment from these materials, and the ensuing
development of benthic anoxia. The extent and duration of these impacts are much more
speculative. Severe effects seem likely within 200 m of the discharge; impacts as far as 500 m
have been demonstrated. The initiation of benthic recovery seems likely within a year, although it
also seems unlikely that it will be complete within one year. And the relative impacts of the
various types of SBFs is speculative given the paucity of field data for laboratory versus field
correlations.
Drilling Fluid Impact Comparison
As described in the preceding sections, the reviewed seabed surveys measured either
sediment or biologic effects from discharges of either WBFs or SBFs. Specifically, indicators of
drilling fluid impact of seabed sediments are determined by measuring drilling fluid tracer
concentrations (as either barium or SBF base fluid) in the sediment at varying distances from the
drill site in an attempt to determine fluid dispersion and range of potential impact. Another class
of impacts frequently measured are benthic community effects. The purpose of these studies is to
assess potential drilling fluid affects such as increased metals and/or anoxia on biota.
Exhibit 9-3 summarizes the major impacts arising from the discharge of WBFs and SBFs.
The distance in which SBF tracers are detected (100 m to 2 km) is much less than that of WBF
(400 m to 35 km). Likewise, the impact on the biologic community is not as far-reaching for SBFs
(50 m to 500 m) as for WBFs (25 m to 2,000 m).
-------
9-15
Exhibit 9-3. Water-based and Synthetic-Based Drilling Fluid Impact Comparison
Studied
seabed
impact
Elevated
tracer cone.
(d)
Negative
community
impact
Water-Based Fluids (a)
Sediment
Fraction of
studies
noting
impact (c)
9/10
~~
Max
range of
impact
400m-
35km
"
Biota
Fraction of
studies
noting
impact (c)
1/1
7/8
Max
range of
impact
1.6km
25m-
2km
Synthetic-Based Fluids (b)
Sediment
Fraction of
studies
noting
impact (c)
23/23
Max
range of
impact
1,000m-
2,000 m
Biota
Fraction of
studies
noting
impact (c)
—
4/6
Max
range of
impact
~~
50m-
500m
(a) A total of 17 water-based fluid seabed survey studies were reviewed.
(b) A total of 28 synthetic-based fluid seabed survey study sites were reviewed.
(c) The fraction equals the number of studies noting an effect from the total number of studies measuring the
corresponding impact.
(d) For water-based fluids the measured tracer in both sediment and biota was barium (see Exhibit 9-1); for
synthetic-based fluids either total petroleum hydrocarbons or the synthetic fluid was measured (see
Exhibit 9-2).
9.2.2 Study Limitations
One of the major limitations in comparing data between the seabed surveys was the
inconsistency in sampling methodology that was used, both spatially and temporally. The
reviewed studies were often conducted using a variety of different sampling methods. Spatially,
sampling locations were determined or chosen in one of several ways. Some studies established
monitoring sites located radially from the discharge point. Others chose the drilled well location
as the hub of the radial or intersecting transects. The Candler seabed study used the four compass
directions as the transects, whereas the Daan study used only two transects, the direction of which
was determined by the prevailing water current (Candler et al., 1995; Daan et al., 1996).
In one study (Daan et al., 1996), results of the pre-discharge survey were the basis for
changing the transect orientations from cross-bathymetric to isobathymetric orientation. This
invalidates comparison between these survey years. In another study (Schaanning, 1995), two
reference stations were reasonably located at 5-6 km distance from the well site. However, these
reference stations also showed a clear temporal pattern in sediment Ba and total hydrocarbon
(THC) levels that suggest potential drilling waste contamination. Specifically, reference station
THC levels decreased from 2.3 mg/kg to 0.25 mg/kg, to 0.09 mg/kg over 1990, 1991, and 1992
surveys. Reference station barium levels decreased from 265 mg/kg to 78 mg/kg to 55 mg/kg over
-------
9-16
the same period. These results throw some doubt on the validity of the reference stations despite
their appreciable distance from the drill site.
Other variations in sampling are the sampling point locations on each of the transects. For
example, sampling stations in one study were located 100 m and 500 m from the discharge point
(U.S. DOI, 1977). In another, sampling stations were located much closer, e.g., 25, 65, and 85 m
(CSA, 1988). In addition, several seabed surveys of WBF discharge used underwater TV (UTV)
in which divers filmed the seabed. However, the UTV of locations where cuttings were noted
were not necessarily the location of these sampling stations (CSA, 1988).
Sample collection protocols often varied between studies. For example, in the North Sea
Ula Well site seabed study, only the top 1 cm of sediment was collected and analyzed for ester
concentrations (Smith and May, 1991). Other studies have collected deeper sediment cores, e.g.,
from the upper 2 cm for the Gulf of Mexico study site, or from the upper 10 cm for the Dutch sector
North Sea (K.14-13) study sites. This difference hi sampling protocol has led authors to different
conclusions. In the Smith and May study, the authors concluded that because the SBF base fluid
was no longer detected in the sediment seabed, recovery had occurred. Other authors have
concluded that synthetic based fluid migrated deeper into the sediment, suggesting that vertical
redistribution is occurring as well as horizontal migration and redistribution.
Temporally, sampling was conducted using many different time interval configurations.
Several studies conducted a pre-discharge survey in order to collect background information on
the site and as a comparison or control for the drilling impact assessment. However, not all
studies conducted pre-discharge surveys. Instead, reference stations, often located at arbitrary
distances from the discharge point or well were used. Often, the seasonally of the pre-discharge
survey was not maintained in later post-discharge surveys. Biologic parameters such as
abundance, species diversity, and species richness are particularly seasonally dependent. Though
spatial reference stations provide relative data to that collected hi the vicinity of the discharge
point, a combination of pre-discharge and post-discharge sampling surveys during the same season
provides a more accurate comparison.
Though most studies reviewed included at least one reference station within the study
design, several studies, such as the Mustang Island, Texas study (U.S. DOI, 1977) did not collect
samples from such a station. The importance of a reference station is to provide the background or
control information against which changes can be measured. The absence of background data
during each sampling event discounts environmental effects, such as the above mentioned seasonal
effects impinging on a larger area.
Several studies, such as that in the Beaufort Sea conducted the pre-drilling survey in the
early spring, the first post-drilling survey hi late spring and the -final survey in late summer
-------
. 9-17
(Northern Technical Services, 1981). Benthic community structure undergoes significant changes
during the spring and summer as growth and development occurs. This is compounded by the
Arctic location which has a very short but intense growing season. The authors in this study
mention seasonal impacts as a source of data variability, however, they neither designed the study
to account for this variability nor conducted an analysis of the developmental effect on the benthic
community during the growing season. Instead, the lack of a decrease in values of abundance was
interpreted as an indicator of no impacts by drilling effluents, rather than an indicator of potential
interference in benthic growth (Northern Technical Services, 1981). The absence of a reliable
temporal control results in a dependence on spatial reference station integrity, which may be
compromised by discharge impacts or natural interstation differences.
Due to the importance of sampling methodology in influencing the type of results generated,
the lack of a standard sampling protocol or methodology affects the level of confidence in the data.
Therefore, data generated from different methods may not always be directly comparable.
Limitations were also found in data analysis and interpretation as presented by the authors.
One issue was that of the treatment of data outliers. In the Candler synthetic-based fluid study, the
mean total petroleum hydrocarbons (TPH) was used to represent the concentration of TPH in the
sediments. However, a closer look at the raw data reveals one replicate sample with a large TPH
concentration decrease and three replicates with a concentration increase. The presentation of
average TPH in all replicates masks a potential trend demonstrating synthetic-based fluid
transport.
Two issues related to data analysis concern the broader environmental field study
problems of natural, sampling, and analytical variability as well as the statistical power of
analyzing and interpreting the data gathered. Because of high levels of natural, sampling, and
analytical variability and high costs inherent to marine field studies, the statistical power of such
studies is limited. That is, in order to detect an effect that is statistically significant, the magnitude
of the change in a given parameter ranges from "large" for chemistry data to "very large" for
biological data. Many of the surveys reviewed concluded that the discharge of drilling fluids and
cuttings do not produce an effect on biota or have shown statistically significant adverse effect
only to a limited spatial extent, i.e, to several hundred meters. For example, the CSA, 1989 study
at the Pensacola Block 996 states that "...only catastrophic, large scale changes (e.g., complete
mortality) would be evident from these [observed photographic] data. Qualitative and quantitative
visual data revealed that such mortalities did not occur." Even in the Santa Maria Basin, study, one
of the most sophisticated and well-funded studies conducted, sampling at 60 photoquadrants per
station per cruise resulted in the ability to statistically resolve 70% reductions or greater in coral
coverage. This level of detectability gives some measure of definition to and confidence in the
study's conclusion that "No statistically significant changes were noted."
-------
9-18
In summary, the lack of standard sampling methodology, differing monitored and analyzed
parameters and differing study purposes presented in the reviewed articles limits the ability to
compare effects of WBF and SBF on the seafloor. However, realizing the data limitations, useful
information can be extracted from the various studies and used in evaluating general trends and
ranges of impacts.
9.3 Summary of Relevant Field Studies
9.3.1 Water-Based Fluids
Zingula, R.P. 1975. Effects of Drilling Operations on the Marine Environment, in:
Conference Proceedings on Environmental Aspects of Chemical Use in Well-Drilling
Operations, Houston, Texas, May 21-23,1975.
The author described observations of cuttings piles in drilling and post-drilling sites in the
Gulf of Mexico. According to the author, diver surveys and side scan sonar records have shown
typical accumulation in the Gulf of Mexico to be approximately 150 feet in diameter (46 meters),
with the outline being circular, elongate, or star burst, depending on currents. Maximum elevation
of these piles immediately after drilling a well appears to be less than 3 feet (1 meter). Several
months after drilling, the height of the cuttings piles is less than 6 inches. No specific observations
were cited to support these data.
In 1971, cuttings piles were photographed while drilling occurred in South Timbalier
Block 111. The water depth was approximately 80 feet (24 meters). Photographs were taken
below the platform to illustrate "normal" bottom conditions and 70 feet downcurrent where
cuttings were present. According to the author, mobile organisms such as crabs were moving
around on top of the fresh cuttings piles.
In order to observe cuttings after cessation of drilling, a site was chosen in South
Timbalier Block 172, which had not been drilled for 8-1/2 months. Water depth was 110 feet
(33.5 meters). The first dive was to record "typical" bottom conditions in the Gulf, outside the
area of any cuttings accumulation. The sea bottom consisted of a thin surface layer of very soft and
unconsolidated mud, underlain by sticky clay with some sand. The bottom was highly burrowed,
and there were numerous whole and broken mollusk shells.
The second dive identified a pile of cuttings. The surface was also highly burrowed,
indicating the presence of numerous benthic organisms. In addition, there was a thin accumulation
of very soft and unconsolidated mud, indicating that marine sediments are already covering the
cuttings.
-------
9-19
A sample was taken of the top two inches of sediment cuttings at the location of the second
dive. The cuttings were somewhat rounded by partial disaggregation of the clays from the
swelling due to seawater adsorption and possibly from abrasive current action. These clay chips
also showed a brownish oxidation on the exterior, further evidence that the chips were undergoing
weathering.
Fauna in the cuttings sample were compared to that found in the "normal" sea bottom
sample. According to the author, both samples contained essentially the same fauna, and in
essentially the same abundance. Present in both were nearly 30 species of foraminifera, more than
15 species of mollusks and micromollusks, several species of bryozoans (both free specimens and
coating mollusk shells), echnoid spines, ophiuriod ossicles, crab fragments, etc.
Ray, J.P. andE.A. Shinn. 1975. Environmental Effects of Drilling Muds and Cuttings, in:
Conference Proceedings on Environmental Aspects of Chemical Use in Well-Drilling
Operations, Houston, Texas. May 21-23, 1975.
Diver observations of the benthic environment in the vicinity of a drilling platform were
described by the authors. During cuttings discharge, the heavier cuttings fall straight to the bottom
to add to the cuttings pile. According to the authors, there is no doubt that sessile benthic
organisms which cannot move about are buried by the cutting pile.
In depths below the effects of wave action, the cuttings piles produce a hard substrate
capable of supporting a diverse and large number of organisms. It must be noted that this study did
not collect any sediment cores so that no accounting of the benthic community was taken, either
pre- or post-drilling. The authors, however, concluded that there are no observable detrimental
effects on the marine life beneath Gulf of Mexico platforms.
U.S. Department of the Interior. 1977. Baseline Monitoring Studies, Mississippi, Alabama,
Florida, Outer Continental Shelf, 1975-1976. Volume VI. Rig Monitoring. (Assessment
of the Environmental Impact of Exploratory Oil Drilling). Prepared by the State
University System of Florida, Institute of Oceanography. Contract 08550-CT5-30,
Bureau of Land Management, Washington, D.C.
A study was conducted to provide a pre-, during-, and post-drilling assessment of selected
biological, chemical and geological aspects of the environment in the vicinity of an exploratory
drilling well. The monitoring survey was centered on a drilling location near the north lease line
of Mustang Island (Texas) Block 792. Water depth was approximately 36 m.
The sampling pattern was in the form of a wheel with eight spokes centered on the well.
Sampling points were located at distances of 100, 500, and 1,000 m from the drill site along each
-------
9-20
spoke. Thus, there were a total of twenty-five sampling points, including the drill site before and
after operations and twenty-four points during drilling.
For clay mineralogy and standard sediment parameter analyses, two sediment samples
were collected from each station by a diver filling PVC cores with sediment. A 9.1-m semi-
balloon trawl was towed at a speed of three to six km/hour to collect macroepifaunal samples
from each of the sampling points for trace element and histopathological analyses. The low
number of epifauna in the study site limited histopathological examination to specimens of only
two species of nektonic shrimp. One sediment core sample was also collected by divers at each
station. The core was then subsampled for foraminifera and the remainder of the core was
archived.
The clay mineralogy of the bottom sediments consisted predominantly of smectite followed
by illite and kaolinite. Smectite levels did not change throughout the study period, however, illite
levels significantly increased, whereas kaolinite decreased during and after drilling. Sand, clay
and CaCO3 levels increased and silt levels decreased during drilling operations.
During the active drilling phase, the authors noted that drill cuttings were specifically
observed at only four 100-m periphery stations and one 500-m periphery station. Drill cuttings
were still observed at these same five stations in the after-drilling phase but were notably less
abundant
The foraminiferal community composition indicated a "stressed environment" prior to
drilling operations, and drilling activities further increased the stress. Total and live specimen
abundance in samples collected during drilling were significantly less than those in the pre-drilling
samples. The greatest effect on specimen abundances occurred along the 100-m periphery, but
adverse effects were demonstrated out to the 1000-m periphery. However, the authors did not
state if the cores at 100 m where the benthic fauna were sampled included cuttings samples.
Ray, J.P. andR.P. Meek. 1980. Water Column Characterization of Drilling Fluids Dispersion
from an Offshore Exploratory Well on Tanner Bank, in: Symposium, Research on
Environmental Fate and Effects of Drilling Fluids and Cuttings, Lake Buena Vista,
Florida, January 21-24,1980. API, Washington, DC.
From January to March of 1977, a drilling muds and cuttings discharge monitoring program
was conducted from a semi-submersible drilling platform on Tanner Bank, 161 km west of Los
Angeles, California. The drill site was located in 63 m of water. Discharges during the study
were from a 0.3 m diameter pipe located at a depth of approximately 12 m below the surface of the
water. Photographic records were made by scuba divers using 35 mm stills and 16 mm movies.
Surveys of bottom conditions directly beneath the discharge and in adjacent areas were made from
-------
- 9-21
a research submersible. Observations and aerial photographs of plume characteristics also were
made from helicopters.
Diver observations showed that as cuttings exit the discharge pipe, the materials
simultaneously separate in three directions: upward, downward and horizontally. The heavier
cuttings and some associated mud began an immediate vertical drop. Cuttings were often "glued"
together by drilling mud and fell to the bottom as large aggregates. The authors hypothesized that
this may be a mechanism for the transport of small quantities of undiluted drilling mud directly to
the sea floor beneath the discharge point. However, the divers observed that much of the mud
adhering to the cuttings was washed off as they fell through the water column. These lighter
fractions dispersed horizontally under current influences.
Observations made beneath the platform and on the nearby reef from the research
submersible showed no visible signs of mud or cuttings accumulation. The authors stated that due
to the high energy water movements present on Tanner Bank, these results were not unexpected.
Meek, R.P. andJ.P. Ray. 1980. Induced Sedimentation, Accumulation and Transport Resulting
from Exploratory Drilling Discharges of Drilling Fluids and Cuttings on the Southern
California Outer Continental Shelf, in: Symposium, Research on Environmental Fate
and Effects of Drilling Fluids and Cuttings, Lake Buena Vista, Florida, January 21-
24,1980. API, Washington, DC.
From January to March of 1977, a drilling fluids and cuttings discharge monitoring
program was conducted from a semi-submersible drilling platform on Tanner Bank, 161 km west
of Los Angeles, California. The drilling site was located in 63 m of water. The authors
investigated sedimentation because of concerns that accumulations of sediments including cuttings
could smother important biotic assemblages such as the relatively rare stylasterine hydrocoral,
Allopora californica.
To evaluate the spatial and temporal distribution of settled solids, 19 sediment traps were
placed at various distances around the exploratory drilling platform. In addition, 9 pre-
operational, 45 operational, and 11 post-operational sediment grabs were taken at varying
distances from the drilling platform to evaluate accumulation and transport of the settling
materials. A pair of modified Van Veen samplers were used to capture undisrupted surface
sediments. Both sediment and grab samples were analyzed for total solids and WBF trace element
concentrations of barium, chromium, and lead using atomic absorption spectroscopy.
Over the 85-day study period, 2,854 barrels of muds and cuttings were discharged.
Cuttings discharge accounted for approximately 96% or 825,530 kg of the total discharged solids.
Based on particulate composition, water depths and currents, the largest cuttings falling at speeds
of 10 cm/sec fell straight down and would not reach traps just outside the platform perimeter. An
-------
9-22
analysis of the materials collected from traps located at 65 m and 120 m downcurrent of'the
discharge source demonstrated that finer materials were captured at the 120 m trap as would be
expected given lower settling velocities as particle size decreases. However, both traps captured
some fine cuttings and mud components with low settling velocities (less than or equal to 1
cm/sec). This indicated to these authors that within 200 m of the discharge, some aggregation of
fine particles has also occurred.
I
Based on cuttings fall velocities, the decreasing measured sedimentation rate with
increasing distance from the source, and the conglomerate effect of flocculation of drilling fluid
components, the authors stated that the vast majority of the solids unaccounted for most probably
fell to the bottom within the 50 m radius directly beneath the platform. From direct observations
made by divers and submersible craft during the course of this study, who noted the absence of
cuttings piles, the authors concluded that the majority of these settled solids were resuspended
from the sea bed and redistributed. The authors calculated from sediment trap and adjacent pre- an
post-drilling grab data that 70 to 80% of the settled solids and components were transported.
Houghton, J.P., et al. 1980. Drilling Fluid Dispersion Studies at the Lower Cook Inlet, Alaska,
C.O.S.T. Well, in: Symposium, Research on Environmental Fate and Effects of Drilling
Fluids and Cuttings, Lake Buena Vista, Florida, January 21-24, 1980. API, Washington,
DC.
This study presents results of oceanographic studies and measurements and modeling
predictions of the fate of discharged fluids and cuttings in the environment. The Lower Cook Inlet
Continental Stratigraphic Test (COST) well was drilled between June 7, 1977 and September 26,
1977 with the Ocean Ranger semi-submersible drilling vessel. The well was located in the
central portion of Lower Cook Inlet approximately 57 km WSW of Homer, Alaska and 38 km ENE
of Augustine Island. The water depth at the site was 62 m.
The physical marine environment in Cook Inlet is dominated by large tidal fluctuations and
strong currents. The authors measured these oceanographic parameters. Mean and diurnal ranges
were calculated to be 4.6 m and 5.3 m, respectively. Currents were measured at the COST well
using current drogues and two arrays of Endeco 105 current meters. Current meter data indicated
mean maximum flood currents of 52, 62, and 78 cm/sec for meters placed near the bottom, at
midwater, and near the surface, respectively. Mean maximum ebb currents were 42, 68, and 104
cm/sec, respectively at similar depths.
The seabed in the COST well area was reported to be typically sand or gravel waves, with
heights occasionally greater than 3 m. Sea floor reconnaissance at the well site and adjacent areas
was conducted using UTV and various bottom samplers. The authors mapped the drilling mud
plume upon discharge using a dye injected into the drilling effluent. In addition, plume modeling
was conducted and results were compared to field data.
-------
_ _ -. •-.-.•: _ ; _ _ 9-23
Bottom sampling and specially designed drilling effluent traps were used to define
deposition of cuttings on the sea floor in the vicinity of the drilling vessel. Two specially
designed drilling effluent traps were constructed to measure the potential deposition rates and their
particle size distribution. One trap (T-2) was deployed approximately 2.9 km WNW of the Ocean
Ranger; the other trap (T-l) was deployed 100 m NNE of the discharge point from the platform.
Samples from the drilling effluent traps were passed through a 0.85-mm screen and the portion of
the sample larger than 0.85 mm was examined under a microscope on a grain by grain basis for the
presence of cuttings. Approximately 2.4 gm of cuttings were identified in T-l giving a calculated
deposition rate of 5.24 x 103 g/hr/nf. No cuttings were identified in the control trap T-2.
Bottom samples were obtained with a Souter-Van Veen grab sampler at various locations
near the drilling vessel. Core samples 8 cm in diameter were taken from the sampler, sectioned
vertically at 0.5-cm intervals, then screened, and examined for cuttings (defined as particles
greater than 0.85 mm in diameter). These analyses indicated that the sea floor was sufficiently
mobile to entrain cuttings to a depth of at least 12 cm into the sea floor by the end of the well
(approximately 3 months duration). The maximum cuttings percentage in the sediments identified
in any bottom sample was less than 3 percent by weight and was found 100 m north of the
discharge. Analysis for barium sulfate and barium showed that drilling mud was being carried to
the sea floor with the cuttings. Though the authors do not state in the text, presented data indicate
that 1 .34 mm cuttings are found 400 m north of the platform with slightly elevated barium
concentrations of 680 |ag/g in the corresponding sediment sample. Background or pre-drilling
barium sediment concentrations were 560
The authors concluded that the heavier cuttings material deposited on the sea floor was
entrained vertically into the sediment since the sandy bottom was quite mobile. Benthic sampling,
core analysis, and UTV examination verified that cuttings did not accumulate on the sea floor as a
cuttings pile. In addition, the relatively low increase in sediment barium levels suggests that near-
bottom currents agitate newly fallen cuttings with the natural sands exerting a washing action that
cleanses cuttings of adhering barite.
Lees, D. C. and J.P. Houghton. 1980. Effects of Drilling Fluids on Benthic Communities at the
Lower Cook Inlet C.O.S.T. Well, .in: Symposium, Research on Environmental Fate and
Effects of Drilling Fluids and Cuttings, LakeBuena Vista, Florida, January 21-24,
1980. API, Washington, DC.
The major purposes of this study were to (1) determine species composition and
abundance of the benthos in the area of the well site, and (2) evaluate the extent to which changes
were attributable to drilling activities. The Lower Cook Inlet Continental Stratigraphic Test
(COST) well was drilled between June 7, 1977 and September 26, 1977 with the Ocean Ranger
semi-submersible drilling vessel. The well was located in the central portion of Lower cook Inlet
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9-24
approximately 57 km WSW of Homer, Alaska and 38 km ENE of Augustine Island. The water
depth at the site was 62 m.
Benthic samples were obtained by Ponar grab samples before, during and at the conclusion
of drilling operations. For each of the time periods, the number of species, species diversity, and
number of organisms were evaluated for 10 stations, each at 100 m north, 200 m north, and the
control located 1,700 m east of the drilling vessel.
Results are presented in Exhibit 9-4. The authors mentioned that the increase in the number
of organisms and variation in the number of species and species diversity for the June, My and
September time points (corresponding to before, during and after drilling) is most probably due to
seasonal variations. However, the authors did not discuss that compared to the control location
samples, the number of organisms had substantially decreased in the during- and post-drilling
surveys at both the 100-m and 200-m locations.
Mariani, G., Sick, L., and Johnson, C. 1980. An Environmental Monitoring Study to Assess the
Impact of Drilling Discharges in the Mid-Atlantic. III. Chemical and Physical
Alterations in the Benthic Environment, in: Symposium on Research on Environmental
Fate and Effects of Drilling Fluids and Cuttings. Lake Buena Vista, Florida, January
21-24,1980. API, Washington, DC.
' The objective of this study was to characterize and determine chemical (trace metal) and
physical (grain size, clay mineralogy) changes of the sediment. This study also analyzed tissue of
three representative benthic taxa for trace metal content: brittle stars (primarily Amphioplus
macilentus), molluscs (primarily Lucinomafilosa) and polychaetes.
Two benthic sampling surveys were conducted. A pre-drillmg survey was conducted in
July and August 1978 and a post-drilling survey was conducted in July 1979. The pre-drilling
survey area comprised a 1.6 km radius around the well site while the post-drilling survey was
extended to a 3.2 km radius.
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9-25
Exhibit 9-4. Comparison of Sampling Area of Averages for Numbers of Species, Organisms,
and Species Diversity for the Survey Periods
Survey
Period
June
July
September
June
July
September
June
July
September
100-m
200-m
Control
Mean number of species (S)
9.9 ± 3.2 (a)
9.0 ±2.1 '
10.7 ±1.6
12.4 ± 2.5
11.3 ±2.7
8.5 ±3.1 (b)
17.5 ±-3.5
15.8 ±5.7
Mean number of organisms (N)
35.1 ±21.3a
28.2 ± 14.4
59.7 ±29.9
41.8 ±9.9
41. 4 ±20.5
43.3 ± 37.4b
80.0 ±6 1.4
183.7 ±110.4
Mean species diversity (H)
2.10±0.4a
1.98 ±0.51
2.00 ± 0.23
2.16 ±0.48
2.17 ± 0.23
1.51±0.31b
2.70 ±0.40
1.78 ±0.54
(a)
(b)
Based on samples 3,4,11, 16,17,18,19 in the area of both 100-m and 200-m stations.
Based on samples 28,29,30, and 31 about 1,000 m from Anchor Buoy 4 (AB-4).
Six samples were collected with a Smith-Mclntyre or modified Ponar Grab at each station
for the physical, chemical, and biological analyses. Upon retrieval of each grab, two sediment
cores (one for sediment granulometry and one for trace metal analyses) were taken near the center
of the grab.
The physical alterations that took place during the post-drilling survey included increased
percentages of clay size particles within the immediate vicinity of the well site (46 meters) and
extending out to approximately 800 meters. The increased percentages of clay within the sampling
grid were accompanied by changes in proportions of clay minerals in the area. The authors stated
that these changes in clay percentage and mineralogy suggest that fine materials were deposited
around the well site during drilling operations.
Increases in the concentration of lead, barium, nickel, vanadium, and zinc for bottom
sediments were detected during the post-drilling survey. The authors presented metals
concentration data as a spatial distribution, highlighting the trend of metals in sediment
concentrated around the drill site in the pre-drilling survey and distributed at low but fairly even
concentrations to 1.6 km in the post-drilling survey. Barium concentration increased 21 fold at 1.6
km, lead increased 3.6 fold at 200 m, nickel increased 2.5 fold at 100 m, and vanadium increased
4 fold at 100 m.
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9-26 .
Analysis of tissue samples of brittle stars, molluscs and polychaetes collected during the
post-drilling survey revealed that each group had significantly higher barium and mercury content
than tissue samples collected during the pre-drilling survey. The barium concentration in
mollusks, brittlestars, and polychaetes collected at 1.6 km increased 20 fold, 133 fold, and 40
fold, respectively, whereas mercury concentration increased 4 fold, 18 fold, and 30 fold,
respectively at the same distance. Increased mercury content was detected in these organisms
despite the fact that data showed mercury concentrations in the sediment were below the detection
limit of 0.05 p.g/g, indicating that the mercury was bioaccumulating.
Menzie, C., Maurer, D., and Leathern, W. 1980. An Environmental Monitoring Study to Assess
the Impact of Drilling Discharges in the Mid-Atlantic. IV. The Effects of Drilling
Discharges on the Benthic Community, in: Symposium on Research on Environmental
Fate and Effects of Drilling Fluids and Cuttings. Lake Buena Vista, Florida, January
21-24, 1980. API, Washington, DC.
The objective of this paper was to describe the short-term environmental effects of drilling
fluids and drilled cuttings on marine benthos around exploratory well NJ 18-3, Block 684 on the
Mid-Atlantic Continental Shelf. The study was conducted within two weeks following the
termination of drilling. The leased block was located approximately 156 km off the coast of New
Jersey and had an approximate water depth of 120 meters.
Two surveys were conducted to examine the abundance and composition of the benthic
fauna in the vicinity of the well site. A pre-drilling survey was conducted in July and August 1978
and a post-drilling survey was conducted in July 1979. The pre-drilling survey area comprised a
3.2 km diameter area around the well site while the post-drilling survey was extended to a 6.4 km
diameter area. ~
UTV surveys were conducted during the pre- and post-drilling surveys to provide
information on the spatial distribution of megabenthic epifauna around the well site and to examine
physical changes in the benthic environment resulting from drilling operations. Ten UTV transects
(200-1,000 m in length) were made throughout the survey area during the pre-drilling survey,
while 11 transects (150-900 m in length)~were made during the post-drilling survey.
During the pre-drilling survey, 40 benthic stations were sampled, of which 22 were
analyzed in a radial pattern around the well site, while during the post-drilling survey, 48 benthic
stations were sampled, of which 41 were analyzed. The rest of the samples were held for later
possible analysis. Six grab samples were collected at each station, of which two were analyzed
for fauna while the remainder were held for future analysis.
Benthic samples were washed on a 0.5 mm mesh sieve to remove silt, clay, and fine sands.
The material retained on the sieve was preserved with 10% buffered formalin-Rose Bengal
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9-27
solution. Macrobenthos were sorted from these samples and identified with the aid of
stereoscopic and compound microscopes.
Seafloor UTV observations during the pre-drilling survey revealed a nearly featureless
bottom topography interrupted by burrowing and feeding mounds of benthic invertebrates. During
the pre-drilling survey, the sediments were comprised of medium-fine sands with a silt and clay
content of 16-25%. During the post-drilling survey, bottom UTV observations revealed that
sediments in the immediate vicinity (approximately a 75 m radius) around the well site were
comprised of patches of drilling discharges (primarily semi-consolidated, natural subsurface clay
materials) which altered the microtopography of the area. Mounds of this material were generally
less than 10 cm in height. Debris (e.g., small pieces of pipe, tires, rope) was also observed in the
immediate vicinity of the well site. Side scan sonar showed the bottom scour marks of anchor
chains radiating out from the well site. Sediments in areas beyond the immediate vicinity of the
well site appeared similar to those observed during the pre-drilling survey.
Fish (primarily hake, Urophycis spp.) and crabs (primarily Cancer borealis) increased
substantially between pre- and post-drilling surveys in the immediate vicinity of the well. The
authors speculated that these organisms may have been attracted to the region as a result of the
increased microrelief afforded by the cuttings accumulations. High densities of sand stars were
observed near the well site, apparently associated with accumulations of mussels (Mytilus edulia)
that had fallen from the drilling rig and associated anchor chains.
Sessile megabenthos (pennatulids) and macrobenthos were subjected to burial by drilled
cuttings within the immediate vicinity (i.e., within approximately a 75 m radius) of the well site.
Measures of species diversity, species richness, and species evenness obtained prior to the
onset of drilling were high and relatively constant over the sampling area. Species diversity of
macrobenthos collected during the post-drilling survey were within the general range observed for
the shelf-break region, though some values were lower. The lowest values during the post-drilling
survey were observed in the immediate vicinity of the well site (75 m). Lower numbers of species
generally reflect the lower numbers of organisms observed at some stations.
Based on the patchiness in the distribution of the species and in density, the author
hypothesized that the variability represented differences between plots in which the infauna had
been buried by cuttings and those which had escaped burial or in which recolonization had
occurred, but supporting data were not presented.
Differences in the nature of infaunal assemblages were particularly clear when pre- and
post-drilling survey data for densities of major taxa were compared. Pooled densities of annelids,
molluscs, echinoderms, and crustaceans were all lower in the post-drilling survey.
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9-28
In summary, this study concluded that the discharge of drill cuttings caused local and at
least short-term effects on the fauna in the vicinity of the well site. Increases and/or decreases in
abundance were probably related mostly to: (1) physical alterations of the substrate (e.g., rapid
deposition and burial, increased surface reliefer increased clay content of the sediment), as well
as (2) effects of predation by hake, crabs, and starfish. No toxic effects were identified.
EG&G Environmental Consultants. 1982. A Study of Environmental Effects of Exploratory
Drilling on the Mid-Atlantic Outer Continental Shelf-Final Report of the Block 684
Monitoring Program. 1982. Prepared for Offshore Operators Committee. October
1982.
This survey is the second in a series conducted at the exploratory well site NJ 18-3, Block
684 on the Mid-Atlantic Outer Continental Shelf. This survey was taken one year after drilling
operations had stopped at the site. Forty-one sites were sampled ranging from 23 m to 3.2 km
from the discharge location. The study evaluated the fate of drilling fluids discharges based on: 1)
percent clay, 2) trace metal concentration (Ba, Cr, V) in the sediment, and 3) benthos impacts
(trace metal concentration in organisms and density of mega and marcobenthos). Analysis of this
survey indicated the percent clay levels decreased from the drill site out to 800 m measured during
the first study, to levels common with predrill levels. However, several patches of increased
clays were measured out to 750 m. Because trace metal leachate levels measured in the first post-
drill survey did not link to discharge characteristics provided by Ayers et al (1980), analysis for
trace metals was limited to barium, chromium, and vanadium (Ba, Cr, V). Ba measurements from
the second study indicate a shift in the Ba concentrations in the direction of the predominate current
(southwest), with 3-fold increases above predrill levels measured to 400 m from the discharge
point. There appeared to be an even distribution of megabenthos with respect to distance from the
discharge point. All four dominant macrobenthos, although depressed below predrill densities,
increased from densities found during the first post-drill survey. Species richness as with
abundance increased from the first post-drill survey, however they did not reach predrill levels.
Impacts were seen out to 1.2 km. These impacts were not, however, correlated to Ba
concentration. Chromium in increased concentration from predrill levels was detected in
polychaetes out to 1.2 km from the discharge point.
Northern Technical Services. 1981. Beaufort Sea Drilling Effluent Disposal Study. Prepared
for the Reindeer Island Stratigraphic Test Well Participants. Under the direction of
Sohio Alaska Petroleum Company. 329pp.
Sohio Alaska Petroleum Company (SOHIO) completed the Reindeer Island Stratigraphic
Test (RIST) well in Prudhoe Bay area of the Beaufort Sea in early 1979. A study was conducted
to evaluate the effects of above- and below-ice discharges. At the tune of the study, normal
procedure for handling drilling mud and cuttings from offshore wells was to haul them to an
onshore disposal site.
-------
; 9-29
Tesf Plot 1 was the discharge location at a water depth of 8 m. Monitoring locations were
oriented radially from the discharge point ranging from less than 5 m to 500 m distance from the
discharge point. The control location was denoted as Test Plot 3 which was about 1 km south of
Test Plot 1.
Results at Test Plot 1 indicated a strong sorting of materials by grain size. Larger particles
were deposited closer to the discharge point while finer materials, including drilling muds, were
deposited further away from the discharge point. Freshwater drilling muds readily flocculated
upon discharge into seawater. According to the authors' observations, these floes were loosely
deposited on the seafloor during whiter and could be resuspended with the slightest agitation.
The authors stated that it is likely that flocculation extends to cuttings since clay-sized •
particles in the drilling mud tend to coat cuttings during the drilling process and thus provide sites
for attachment of other clay-sized particles.
Diver observations were conducted at Test Plot 1 on May 4,1979, 4 days after the test
discharge. A 5- to 6-cm thick accumulation of mud and cuttings was observed on the seafloor in
the vicinity of the discharge point. UTV observations the following day indicated a 2- to 3-cm
deposition at a distance 3 m east of the discharge point. The consistency of the deposited
materials was such that materials would be suspended with the slightest agitation. At a distance of
6 m east of the discharge site, 1 to 2 cm of loosely deposited drilling effluents was observed. By a
distance of 30 m east of the discharge, accumulation of drilling muds on the seafloor was estimated
to be less than 0.5 cm thick. Organisms observed during the post-discharge survey at Test Plot 1
included amphipods, a snail, several fish and mysids, an hydroid, an anemone, numerous snail and
isopod tracks, and numerous worm tubes.
Benthic sampling was conducted at Test Plots 1 and 3 prior to and subsequent to the test
discharge of drilling effluents. All samples were obtained using a Petite Ponar bottom grab
sampler. Fifteen random replicate samples were taken at each of the test plots during sampling
periods on April 7-1-0, May 9, and August 3-4, 1979. For the April and May surveys, samples
were obtained through holes augered in the sea ice in random 5 m by 5 m squares within each of
the 50 m by 50 m test plots. For the August survey, randomness in samples was achieved by
drifting in a boat within a 25 m radius of the center of the test plot.
Benthic data were analyzed and are summarized in Exhibit 9-5. The authors calculated the
number of taxa, species diversity, evenness and species richness values by pooling the 15
replicate samples taken at each test plot during the sampling period.
The authors did not seem to stress that the time difference in sampling is strongly affected
by the natural growing season. As presented in Exhibit 9-6, from pre-drilling in April to
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9-30 _-_______._.
immediately after discharge in May, there is a significant increase in the number of organisms per
square meter (abundance) most probably due to the beginning of the growing season. From May to
August, there is a 75% increase in abundance in the control location (Test Plot 3) and a 3%
Exhibit 9-5. Summary of Benthic Data Collected at Test Plots
Collection Date
April 7, 1979
April 8, 1979
May 9, 1979
May 9, 1979
Augusts, 1979
Augusts, 1979
Test
Plot'
1
3
1
3
1
3
Abundance
(aoJm1)
551.1
809.4
1240.0
1529.9
1202.7
2678.0
No. of
Taxa
45
54
63
65
67
76
Shannon
Function of
Diversity
2.96
3.32
3.11
3.50
2.94
3.09
Even-
ness
0.83
0.83
0.75
0.84
0.70
0.71
Species
Richness
6.97
7.91
8.70
8.73
9.30
9.50
Bfiomass
(gm/m2 wet wt)
10.0
29^4
33.9
59.2
18.4
55.0
*Test Plot 1 refers to the discharge location and Test Plot 3 to the control location.
Exhibit 9-6. Comparison of Abundance Data Collected at Test Plots
Abundance
Increase from April to
May Sample
Increase from May to
August Sample
April 7, 1979
1
551.1
—
—
3
809.4
—
—
May 9, 1979
1
1240.0
125%
—
3
1529.9
89%
—
August 3, 1979
1
1202.7
—
-3%
3
2678.0
—
75%
decrease in Test Plot 1. Though the authors do not present the percentage change nor the
percentage difference between the control and test plot data, it is clear that in the time between
May and August there should be a normal increase in numbers of organisms. This lack of increase
in Test Plot 1 implies that the drilling discharges may have interfered with organism population
growth during that lime period.
Trace metal analysis was conducted on replicate Ponar and whole drilling mud samples in
order to detect possible effects of below ice drilling effluent disposal. The majority of the bottom
samples were obtained at random locations within 50 by 50 m of test plot 1 (the discharge site)
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9-31
and test plot 3 (control site). As indicated by analysis of the samples at each of the sites,
variations of trace metals at the test discharge site was similar to variations found at the control
location. According to the authors, these results of the trace metal analysis confirm that drilling
muds are quite swiftly resuspended and removed from the seafloor after initial settlement.
Botkner, M.H. etal. 1985. The Georges Bank Monitoring Program 1985: Analysis of Trace
Metals. U.S. Geological Survey Circular 988.
This study was designed to establish the concentration of trace metals hi sediments prior to
drilling on Georges Bank and to monitor the changes in concentrations that could be attributed to
petroleum-exploration activities. The first cruise of the monitoring program occurred just before
exploratory drilling commenced in July 1981, and nine subsequent cruises were conducted on a
seasonal basis (November, February, May, and July) over a 3-year period. Eight exploratory
wells had been drilled at that time on Georges Bank. The first was started on July 22, 1981, and
the last well was completed on September 27, 1982.
Of 12 trace elements analyzed, only barium was found to increase in concentration during
the period when the eight exploratory wells were drilled. The maximum post-drilling
concentration of barium reached 172 ppm in bulk sediments near the drill site hi Block 410. This
concentration was higher than the pre-drilling concentration at that location by a 5.9-fold factor.
No drilling-related changes hi the concentrations of the 11 other metals were observed hi bulk
sediments at any of the locations sampled in the program. Analyses of sediment trap material for
Ba-enriched matter showed that resuspension can occur up to at least 25 m above the seafloor.
The authors estimated that about 25 percent of the barite discharged at block 312 was
present hi the sediments within 6 km of the rig, 4 weeks after drilling was completed at that
location. In their evaluation of the rate at which barite decreases within the site-specific survey,
the authors considered only the area between the 0.5- and 2-km circles. They also excluded the
actual drill site, where large within-station variability was measured. For almost a year following
completion of the well, the inventory of barite decreased rapidly, with a half-life of 0.34 year.
During the next year, the inventory decreased at a slower rate (half-life of 3.4 years).
To see how far Ba from drilling mud could be traced, the authors analyzed the fine fraction
of sediment at two stations approximately 65 km west of the Block 312 drill site and at two
stations approximately 35 km to the east of the easternmost drill site. At the two western stations
they measured maxima hi Ba concentrations during cruises 8 and 10 hi 1983. The authors were
surprised to find that maxima hi the Ba concentrations, although of lower magnitude, were also
recorded at similar times at the two eastern stations. The maximum value at one eastern stations
on cruise 7 was statistically higher than the mean of the first 6 cruises at the 99.5 percent level of
confidence (t test). These findings were considered significant because they suggested that Ba hi
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9-32
the finest fraction of drilling mud may have been transported over very wide areas of the bank, to
the east as well as to the west.
The barite discharged during the exploratory phase of drilling is associated with the fine
fraction of sediment and was found widely distributed around the bank. Evidence indicated
barium transport in the predominant, westerly current direction as far as Great South Channel (115
km west of the drilling), and to stations 35 km east of the easternmost drilling site, against the
predominant current. Small increases in barium concentrations were measured also at the heads of
both Lydonia and Oceanographer Canyons, located 8 km and 39 km, respectively, seaward of the
nearest exploratory well.
Throughout the 3 years of monitoring, the concentrations of Ba in bulk sediments from the
upstream control stations were fairly consistent with time. On the basis of those data, the authors
f judged that no increase in Ba had occurred at those stations. They found no increases in the
concentration of other metals as a result of drilling at the upstream locations during the 3 years of
monitoring. In contrast, there were measurable changes in the concentrations of Ba in Block 410
(stations 16,17, and 18).'
The scatter in their data indicated to the authors that Ba was not distributed homogeneously
over the sampling area. This heterogeneity was probably caused by the intermittent discharge of
drilling fluids into ocean currents that continuously change direction of flow throughout the tidal
cycle. A few cuttings were found during both year 2 and year 3 at a station located 2 km to the east
of the drill site, in Block 410. On cruise 9, cuttings were observed at all stations within 500 m of
the drill site in Block 312.
At coring stations 50 km west of transect HI, the authors observed an enrichment of the
Ba/Al ratio in surface sediments and interpreted that as evidence for a small recent addition of Ba.
A rough calculation referred to from an earlier report (Bothner et al, 1984) suggested that
69 percent of the barite discharged by all eight exploratory wells could be accounted for in the
sediments within the western half of a circle 130 km in diameter and centered on station 5. They
then concluded mat the barite from drilling mud was associated with the fine-sediment fraction in
low concentration and was widely distributed.
This study demonstrates that drilling fluid solids may be widely distributed over large
areas in relatively short period of time if they are discharged in high energy marine environments
such as the Georges Bank. Transport was observed over distances of 35 - 115 km, both in the
anticipated direction of deposition and opposite that of predominant current flow. This study
indicated that in such environments, assessing low-level, regional-scale contamination effects is
the primary source of concern.
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I '_ • 9-33
Neff, J. M. M. Bothner, N. Maciolek, andJ. Grassle. 1989. Impacts of Exploratory Drilling For
Oil and Gas on the Benthic Environment of Georges Bank. Marine Environmental
Research 27 (1989).
This study was conducted over a three year period to determine the impact of discharges
from exploratory drilling to benthic community of Georges Bank and was conducted in conjunction
with the previous reviewed article by Bothner et al. (1985). The authors conducted benthic fauna
analyses at 46 sample sites that included 31 sites adjacent to two drilling platforms. Sampling
took place quarterly and pre-, during, and post-drilling. The authors indicated changes in the
benthic communities near the platforms during and immediately after drilling activities, but
attributed these changes to natural changes within the community populations.
Continental Shelf Associates. 1988. Monitoring ofDrillsite A in the Gainesville Area Block 707.
Prepared for Sohio Petroleum Company, Houston, TX, April 26, 1988. 124pp.
The purpose of this study was to assess the environmental impacts of proposed exploratory
drilling hi Gainesville Area Block 707 on several seagrass and live-bottom communities.
Gainesville Area Block 707 is located approximately 60 km from the west coast of Florida in
water depths of 21 m.
Two surveys were conducted and results analyzed. Survey 1 was a pre-drilling survey.
The drill rig moved onsite on May 25, 1984, and began drilling discharges on June 3, 1984.
Survey 2 (August 9 - August 23, 1984) occurred during drilling. A third survey was also
conducted, but because it followed a severe hurricane that disrupted the benthos across a wide
area of the northwest Florida continental shelf, most of the results were not used.
According to other studies the authors referenced in this area, plant densities or bottom
coverages within offshore seagrass and algae stands range from 20 to 50%. Halophila species
comprise about 79% of the plant material present while various species of microalgae account for
the remainder. Halophila decipiens was found to be the only seagrass species present in the
vicinity of the Block 707 drill site.
Sampling stations were located within 300 m of the discharge point in a radial pattern.
The closest stations were located 25 m, 65 m, and 85 m from the discharge. Live bottom
monitoring stations were located 25 m and 500 m from the drill site and 3 reference stations were
located greater than 9 km from the drilling operations. Six randomly placed quadrants were
permanently established and photographed. An additional 10 stations were established beyond
300 m during survey 2.
During the second survey, visual observations revealed the absence of all seagrass within
300 m of the discharge site. An accumulation of cuttings around the discharge site was also
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9-34
observed, particularly along the northwest radial within 30 m of the discharge point. Farther from
the drill site, growth was inhibited as a function of the concentrations of the two drilling effluent
indicators, barium and bariumriron ratios in the fine-grained fraction (<63 [im) of surficial
sediments.
To determine whether or not exposure to drilling effluents affected the seagrass, the authors
evaluated the relationships between changes of the indicators of discharged drilling effluents and
the changes in standing crop of the seagrass. The indicators of discharged drilling effluents were
the barium concentrations and bariunriron ratios in the fine-grained fraction (<63 [im) of the
surficial sediments. The fine-grained fraction was analyzed because barium sulfate in the
discharged drilling effluents is in the silt/clay particle-size range and the sediments around the
drill site were sand. Thus, metal concentrations in the fine-grained fraction were more efficient
tracers of the settleable fraction of the discharged drilling effluents. Logarithmic transformations
of the mean changes of these indicators were used in the correlation analysis.
The authors presented Ba:Fe ratio data as well as chromium concentration data. The data
showed a 90% increase in the Ba:Fe ratio at 4,000 m from the discharge point and an 11%
increase in the chromium concentration at 300 m.
Results of analysis indicated that there were statistically significant negative correlations
between changes of the drilling effluent indicators and changes of the seagrass standing crop.
Larger changes in drilling effluent indicators (e.g., increases in sediment Ba levels or of Ba:Fe
ratios) were associated with smaller changes in seagrass standing crop (i.e., although seagrass
standing crop increased, the magnitude of the change was negatively correlated to effluent
indicators).
Both leaf biomass and leaf count increased from the pre-drilling to the during-drilling
surveys, most probably due to the growing season. However, while leaf count increased 1,212%
at the reference station, it only increased 282% and 84%, respectively, at the 4,000 m- and
1,300 m-stations (77% and 93% decreases in growth).
Impacts to the live bottom community at the 25 m station resulted primarily from burial of
cuttings. The authors concluded that smothering by drilling muds and cuttings may have been
important at distances close to the drill site. Farther from the drill site, reduction in the light levels
reaching the seafloor as a result of increased turbidity in the water column was thought to be the
primary factor.
Two follow-up surveys were conducted one year and two years after drilling. According
to the authors, these surveys indicated seagrass recovery had occurred. However, data regarding
the extent of recovery were not provided.
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-:-\r-^: a : : 9-35
Soothe, P.N. andB.J. Presley. 1989. Trends in Sediment Trace Element Concentrations Around
Six Petroleum Drilling Platforms in the Northwestern Gulf of Mexico. In: F.R.
Englehardt, J.P. Ray, andA.H. Gillam (Eds.) Drilling Wastes. Elsevier Applied Science,
London, pp. 3-22. - -
The goal of this study was to determine typical concentrations of drilling fluid residuals in
surface and subsurface sediment within 500 m of six offshore drilling sites in the northwestern
Gulf of Mexico. Three types of drilling sites were studied: exploratory sites as isolated as
possible from other wells; developmental sites with multiple, recently completed wells; and
production sites where considerable time had elapsed since drilling was completed.;:For each of
the three types, a location was chosen in shallow water, i.e., about 30 m in depth and in deep
water, i.e., about 100 m in depth. NOTE::,ln the authors' use of the relative, descriptive terms
"shallow" and "deep" in their report, the term "deep" (i.e., -100 m) is not the same as the term
used in reference to this ralemaking, for which "deep" wells are defined as those in waters greater
than 1,000m in depth. s- —:-»•--.•-•
Sediment was collected at 40 stations around each drilling site using a circularly- and
radially-symmetrical pattern. Background concentrations were determined by analyzing sediments
from 4 control stations located 3,000 m from each drilling site in addition to subsurface sediments
located well below the possible .influence of surface discharges (4-31 cm depth).
Barium mass balance data show that only a fraction of the total Ba, and presumably similar
drilling mud components, are present in near-site sediments. At nearshore study sites,
approximately 94% of the discharged Ba had been transported more than 3,000 m from the drilling
sites. Offshore sites were more variable, showing transport beyond 3,000 m for 16%, 28%, and
53% of the discharged barium. Multiple regression analysis suggested excess sediment Ba
distribution was largely controlled by water depth.
The total excess Ba within 500 m of these sites was highly correlated with the total Ba
used at the site. Thus, the effect of multiple wells on near-site sediments is directly additive.
Discriminant analysis suggested that statistically significant (> twice background levels) Ba
enrichment existed in surface sediments at 25 of the 30 control (3,000 m) stations studied. Ba
levels at "control" sites were up to 4.5 times subsurface background levels. Statistically
significant elevations in sediment mercury concentrations within 125 m of the site (4-7 times mean
control levels) were observed at the Vermillion 321 and High Island sites (both deep water sites)
and were strongly correlated to Ba levels. The High Island site also showed a significant Pb
gradient, showing mean levels within 125 m 5-fold higher than controls and 3.8-fold higher within
500 m; Pb was highly correlated with Ba at this site. Other study sites exhibited patchy
distributions of elevated sediment Pb levels, but no consistent spatial trends.
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9-36
Sediment levels of Cd, Cu, and Zn were determined in only 9 or 10 surficial samples at
each site, so evaluations were tenuous with such small sample sizes. Observations made included
the following. Cd appeared elevated at the High Island and Vermillion 321 sites and was
correlated to Ba at the Vermillion site. Cu showed no consistent trend at any site except for small
elevations within 125 m at the High Island site, and was correlated to Ba. Zn showed consistent
gradients at the High Island and Vermillion 321 sites, with elevation 5-10 times control levels, and
was correlated to Ba and distance at both sites. Within 250 m of the Vermillion 321 and High
Island sites, 4- to 5-fold elevations of hydrocarbons over control station levels were observed.
However, among the six (all gas) platforms, hydrocarbon contamination was generally low.
Continental Shelf Associates, Inc. and Barry A. Vittor and Associates, Inc. 1989a.
Environmental Monitoring in Block 132 Alabama State Waters, Summary Report.
Prepared for: Shell Offshore, Inc.
The program objective as presented hi this report was to determine whether or not drilling
discharges affected the biotic assemblages living in the vicinity of the discharge site. The program
consisted of three sampling elements: 1) continuous recording of near-bottom current speed and
direction; 2) analysis of surficial sediments collected within 1,000 m of the discharge site for
sediment grain size, trace metals, and oil and grease; and 3) sampling and analysis of
macroinfaunal assemblages present within 1,000 m of the discharge site.
Sampling was conducted during four surveys: Survey 1, prior to drilling discharge; Survey
2, two months after drilling discharges commenced; Survey 3, five days after drilling discharges
ceased; Survey 4, eight months after drilling discharges ceased. The sampling pattern consisted of
eight radials centered at the discharge site and oriented toward north, northeast, east, southeast,
south, southwest, west, and northwest. Stations were located along each radial at 122 m, 500 m,
and 1,000 m. In addition, four stations were located at 91 m on the four primary radials, i.e.,
north, east, south, and west. The analyses conducted were: 1) sediment grain size analyses; 2)
chemical analyses; and 3) analyses of biological samples.
Near bottom currents predominantly flowed southeastward and, to a lesser extent,
northwestward. Sand predominated at many of the stations in the study area on all four surveys.
However, sediments did appear to become progressively finer as the program progressed. The
authors found that changes in sediment grain size resulting from drilling discharges could not be
easily separated from non-drilling-related changes. They concluded that changes observed within
122 m of the discharge site were probably related to drilling discharges. Changes of similar
magnitude were observed by the authors farther away, but were thought due to non-drilling-related
causes based on examination of the barium distribution.
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. 9-37
The authors analyzed for 10 trace metals (aluminum, arsenic, barium, cadmium, chromium,
copper, iron, lead, mercury, and zinc) and oil and grease at 16 stations located within 1,000 m of
the discharge site on the four surveys. Their results showed that except for barium, the trace metal
concentrations in the whole-sediment samples were correlated with the quantity of fine-grained
particles in the sediments. Their analysis of the mean concentrations of Bain the fine-grained
fractions were shown to be consistently greater during survey 3 compared to Survey 1 at all
stations located within 1,000 m of the discharge site where trace metal concentrations were
determined. During Survey 4, only one of the sixteen stations was statistically greater than during
Survey 1.
The study states that changes in other trace metals concentrations did not appear related to
drilling discharges. The concentration ranges of aluminum, arsenic, cadmium, chromium, copper,
lead, and mercury in whole sediments were within or near ranges reported in previous studies
conducted in offshore Alabama waters. The authors' statistical analysis revealed no changes that
were attributable to drilling discharges.
The authors found that the mean mercury concentrations in fine fractions during Surveys 2
and 3 were statistically greater than those observed during Surveys 1 and 4. It was concluded that
mercury concentrations were not positively correlated with barium concentrations and therefore,
probably not associated with discharged barite.
At each of the four surveys, the authors collected ten replicate samples, at each of 16
stations, and analyzed them to determine the composition of the macroinfaunal assemblage. The
macroinfaunal assemblage summary parameters (number of taxa, density, diversity, evenness, and
species richness) were calculated for all stations and surveys. The values of these parameters
were within ranges expected for this area and were related to sediment grain size, but not to
proximity to the discharge site. Considerable temporal and spatial variability was observed by the
authors.
The authors used species cluster analysis and dendrograms to reflect the presence of
assemblages typical of nearshore sand and silt habitats throughout the northern Gulf of Mexico.
The authors grouped stations in the clustering analysis primarily on the basis of time of sampling,
and not by sediment texture or distance from the discharge site. Using canonical descriminant
analysis of environmental factors such as time, distance from the drill site, sediment texture, and
trace metals, they indicated that benthic station groupings were determined primarily by season
and not by distance from the discharge site or by drilling discharge tracers such as barium or
percent clay. They found that sediment texture (percent gravel) did account for a small amount of
the variability among station groups.
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9-38 ___
The study concludes that the number of macroinfaunal taxa was not related to either
sediment texture or distance from the discharge site. Individual abundance was correlated with
sediment texture and varied with season, but was not related to distance from the discharge site.
Species diversity (H') was relatively uniform temporally and spatially. The authors indicated that
the observed changes reflect the effects of sediment texture and season on numbers of individuals,
and are not related to distance from the discharge site. Evenness and species richness levels
varied with sediment texture and showed temporal changes. These parameters were not related to
distance from the discharge site.
Continental Shelf Associates, Inc. and Barry A. Vittor and Associates, Inc. 1989b.
Environmental Monitoring to Assess the Fate of Drilling Fluids Discharged into
Alabama State Waters of the Gulf of Mexico, prepared for: Offshore Operators
Committee.
The purpose of this study was to determine whether drilling fluids discharged into
Alabama State Waters outside of the barrier islands can be detected in statistically significant
levels in areas of biological concern located inside the barrier islands. To accomplish this goal,
the study was divided into two monitoring efforts: area-wide monitoring and drill site monitoring.
The area-wide effort involves two principal elements: 1) sampling and analysis of surficial
sediments at 12 stations for grain size, oil and grease content, and concentrations of 10 trace
metals; 2) sampling and analysis of oysters for the same metals at three of the surficial sediment
stations. The report summarizes methods and results of area-wide sampling from Survey I
(February 1986) through Survey VI (June 1988).
Beginning between Surveys IV and V, an exploratory well was drilled in Alabama State
waters Block 132. Between October 9,1987 and February 29,1988, approximately 7,285 m3 of
drilling fluids and 726 m3 of cuttings were discharged. About 79% of the total volume was
discharged between October 9 and November 6,1987 (i.e., prior to Survey V).
In addition to the drilling activity, a major dredging project began during the interval
between Surveys IV and V. Dredging of the Mobile Bay ship channel began in January-February
1987, when about 500,000 m3 were dredged. Dredging resumed in October 1987 (two months
before Survey V) and was expected to continue until February 1990. About 23,000 - 31,000 m3
were dredged per day, with all of the material being placed in the offshore disposal area outside
of the barrier islands.
Also, the data set from drill site monitoring in Block 132 can aid in the interpretation of the
area-wide data set by indicating which variables might be affected by drilling discharges. For
example, if the concentration of a metal were unaffected near the drill site, then changes in the
concentration of the metal in Mobile Bay (where the nearest station is 10. km from the drill site)
could not be attributed to drilling fluids from the well.
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9-39
Ba concentrations increased substantially around the drill site in Block 132 during drilling.
Statistically significant increases in Ba concentrations were detected to a distance of 500 m from
the drill site, and apparent two to five-fold increases in mean Ba concentration were evident at
four 1,000 m stations (though not statistically significant).
Eleven of the 12 stations monitored in Mobile Bay during this study showed no significant
increases in fine fraction Ba concentration or barium-to-iron ratio. At Station 3, the mean of the
Survey V-VI values (318 mg/kg) was about 13% higher than the mean of the Survey I-IV values
(282 mg/kg), and was statistically significant.
This small increase in barium at Station 3 was thought probably due to natural variability
rather than drilling fluids. No significant increases were observed at four other stations located
between Station 3 and the mouth of the bay, where the drilling fluids would enter. Three of these
stations had much higher silt/clay content than Station 3 and were thought more likely to retain fine
drilling fluids deposits.
Increases in concentrations of some metals other than barium occurred around the drill site
in Block 132. Changes hi cadmium and mercury concentrations between surveys were detected,
but these were not attributed to drilling discharges because the changes were spatially uniform and
were not correlated with barium increases. Significant increases in arsenic (one station), copper
(one station), and zinc (one station) were detected, but were attributed to natural sediment
movement or sampling/analytical error associated with the small quantities of fine sediment
available for analysis from one station.
In the area-wide sampling, there were several significant increases in concentration and/or
metal-to-iron ratio for metals other than barium. Cadmium had the highest number of significant
differences (seven stations), followed by arsenic (four stations). Significant differences were also
detected for chromium (Station 12), and lead (Stations 3 and 9). In plots of station means, large
increases between Surveys V and VI were noted for cadmium, copper and lead at Station 3, and
copper at Station 9. The copper increases were not significant hi the statistical analysis, which
used the mean of Surveys V-VI.
Increases in concentrations of these other metals were thought probably not due to drilling
fluids. All of the metals except aluminum and iron, which are normally associated with clay
particles, are present in drilling fluids primarily as trace contaminants of barite. Because barium
is more concentrated in drilling fluids (relative to normal sediments) than the other metals,
increases in these other metals due to drilling fluids were expected to be accompanied by major
increases in Ba. No such increases were seen during the study.
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9-40
Oil and grease concentrations increased significantly at Stations 2, 5, 6, 7, 8, and 11
between Surveys II-IV and Surveys V-VI. The increase at Station 11 can be attributed to an
increase in silt/clay content of the sediments (oil and grease concentrations tended to be higher in
sediments containing more silt/clay). The explanation for the other increases were not known, but
were thought probably not due to drilling fluids, because there were no accompanying increases in
barium concentration.
Drilling fluids discharged to the ocean may contain small amounts of hydrocarbons,
although they are subject to the test of "no visible sheen". At stations around the drill site in Block
132, there were some apparent increases in sediment oil and grease content during drilling, but
these appeared to be related to natural sediment changes as indicated by whole sediment aluminum
concentrations.
There were no statistically significant increases in the concentrations of 8 and 9 metals in
oyster tissue. Arsenic concentrations in both depurated and non-depurated oysters were
significantly higher on Surveys V-VI than on Surveys I-IV. The temporary increase in arsenic
concentration in oyster tissue probably is not due to drilling fluids. There are no oyster data from
the drill site monitoring in Block 132, because no oysters were present there. However, arsenic
concentrations in drilling fluid were no higher than those in the fine fraction of sediments from
Mobile Bay. The reason for the temporary increase in arsenic concentrations in oysters is not
known.
A statistical difference between Surveys V-VI and Surveys I-IV does not necessarily
indicate an effect of drilling. Some significant differences could reflect natural changes that did
not occur during the previous year of "baseline" sampling. Other differences could be due to the
channel dredging project, which began between Surveys IV and V and which continued through the
monitoring program. Unfortunately, conditions in the real world are seldom ideal in the sense of a
controlled experiment.
The reason for increases in metal concentrations between Surveys I-IV and Surveys V-VI
was not known. Possible explanations included the following:
• The first four surveys did not encompass the full range of non-drilling related variations in
trace metal concentrations. Such variations may be attributed in part to natural seasonal
and year-to-year fluctuations.
• The channel dredging project.
The fine fraction at predominantly sandy stations may be different from the fine fraction at
silt/clay stations, or more prone to analytical error; stations with high percentages of sand
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9-41
had highly variable metal concentrations or metal-to-iron ratios on one or more surveys
and support this hypothesis.
Continental Shelf Associates, Inc. 1989. Pre- drilling and Post-drilling Surveys for Pensacola
Area Block 996. Prepared for Texaco Producing Inc.
A monitoring study of a single exploratory well located in approximately 60 m water depth
was conducted in Pensacola Block 996 to detect any obvious impacts to the hard bottom epibiotic
community of nearby live-bottom areas. The study involved collected pre-drilling and post-
drilling video and quantitative still camera data, as well as post-drilling surface sediment
chemistry data. Drill site sediment Ba levels at 3 stations within 250 m of the discharge,
expressed as either bulk phase or fine-fraction values, were 40-125 tunes greater than the average
reference station value (which in turn was about twice the reported background level). Sediment
barium levels (bulk and fine fraction) at 2000 m averaged twice the reference station levels. Bulk
phase sediment chromium levels were only elevated at the drill site; fine-fraction chromium levels
were 50% and 20% above reference levels at 250 m and 500 m, respectively.
Background was defined at three reference stations located approximately 3,500 m from
the drill site. However, reference station values must be regarded with caution for three reasons:
1) predrilling samples were not taken, 2) values obtained in the post-drilling survey (45-70 ppm
Ba; 19-22 ppm Cr) were substantially higher than an earlier, nearby baseline conducted prior to
drilling (29 ppm Ba; 3 ppm Cr), and 3) a continuous distance-dependent decrease hi bulk and fine-
fraction Ba and fine-fraction Cr occurred to the farthest radial array stations, including the
reference stations.
Only "catastrophic, large-scale changes (e.g., complete mortality)" would be detectable
from the photographic and video data collected. No such "catastrophic" effects were observed.
Overall, photographic data from stations within 2,000 m of the drill site showed a 55% decrease
in total biotic coverage for pre- versus post-drilling surveys; reference station values decreased
19%. Overall decreases, at both drill site and reference stations, were primarily due to dramatic
(i.e., 95%) decreases in bryozoan coverage between surveys.
This study presents a typical picture of what exploratory well impacts will be on sediment
chemistry. The significant confounding factor here is the "true" background level of Ba and Cr. If
the earlier study values are used as reference values, then sediment Ba levels are elevated four-
fold at 2 km, and sediment Cr values are 8- to 10-fold higher within 500 m of the discharge. This
range of values is expected for these types of discharges.
Steinhauer, M. etal 1990. California OCS Phase II Monitoring Program Year-Three Annual
Report. Chapter 13. Program Synthesis and Recommendations.
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9-42
The California Outer Continental Shelf (OCS) Phase II Monitoring Program (CAMP) study
is a good example of the difficulties inherent to marine impact assessment. The specific objectives
of CAMP were:
To detect and measure potential long-term (or short-term) chemical, physical, and
biological changes in the benthic environment around development platforms in .areas of
soft-bottom and hard-bottom substrates in the southern Santa Maria Basin.
• To determine whether the changes observed were caused by drilling-related activities or
whether they were the product of natural physical, chemical, and biological processes in
the study area.
The study area is on the southern portion of the Santa Maria Basin OCS. All but one
station were located at water depths ranging from 90 m to 410 m. At the soft-bottom site, a semi-
radial array of stations was located around the proposed future site of Platform Julius in water
depths raging from 123 m to 169 m. At the hard-bottom site, stations were located on high- and
low-relief hard features, and in adjacent soft-sediment locations in 105 m to 213 m of water near
the site of Platform Hidalgo.
In the development of CAMP, its design explicitly addressed the importance of taking
synoptic measurements from replicate samples and keeping replicate data separate. Also, in the
absence of pre-impact sampling it could be argued that control sites and impacted sites always
differed and, in the absence of control sites, it could be argued that change at impacted sites was
not caused by the impact. CAMP's design also employed an optimal-impact study design, with
pre-impact as well as post-impact sampling, and control site as well as impacted site sampling.
Postponement of platform emplacement and drilling at the soft-bottom site and an
abbreviated drilling schedule at the hard-bottom site necessitated changes in the scope and
schedule of the monitoring program. Monitoring at the soft-bottom site was thought to provide
valuable baseline information on physical, chemical, and biological features and processes in the
area. This information was thought to be valuable in the design and execution of future monitoring
studies of platform discharges when the platform is installed at the Julius site.
Although the soft-bottom components of the monitoring program were prematurely
concluded due to a lack of industry activity, certain aspects of the monitoring design were believed
useful. Biological data supported the idea that meaningful levels of change could be detected for
dominant species and for more encompassing parameters such as diversity. Chemical data
supported the idea that barium could be used as a tracer of activity in spite of high, but invariate,
natural levels in the region.
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9-43
Data representing different sampling occasions provided evidence of significant temporal
variation in both the macrofauna and meiofauna. Within-year variations, although significant, did
not follow the same patterns consistently from one year to the next. Nevertheless, these results
were taken to demonstrate the importance of conducting repeated sampling before and after
initiation of drilling activities, to provide a basis for differentiating between natural temporal
variations in benthic community parameters and impacts caused by drilling and production
activities.
Monitoring at the hard-bottom site near Platform Hidalgo provided information on platform
effects and on discharges associated with drilling of seven wells between November 1987 and
January 1989. The original hypothesis for determining platform-related effects established two
major criteria: 1) a before-and-after farfield/nearfield effect (i.e., space-time interaction) and 2) a
change in organism abundance correlated to the dose of drilling wastes (relative flux of chemical
signals, from sediment trap data). Of the 10 species tested for a time-space interaction, only the
solitary coral, Caryophyllia sp., showed such an effect. Due to an incomplete data set from the
sediment trap fluxes at the three stations where a significant time-space interaction was observed
for this species, data are only available fora limited period (November 1987 and October 1988).
There were insufficient number of stations to calculate an analysis of variance with depth
and time as additional covariates. Given these limitations, together with those of limited data from
the sediment traps, the best test of a platform-related effect on Caryophyllia were scatter
diagrams. Neither total sediment flux nor total PAH concentrations were related to the effect,
although in both cases one station that showed a loss of Caryophyllia cover between 1987 and
1988 had a slightly greater relative flux of these materials. However, tests of the relationship
between Caryophyllia sp. abundance in a larger data set indicated a highly significant
relationship between sediment flux and species abundance.
These data would seem to support a hypothesis of impact. However, the authors presented
a disturbing analysis. Although the change in percent cover of Caryophyllia seems to support a
conclusion of drilling-related impacts, it was noted that the change between sampling periods was
less than 50 percent, the original power analysis indicated that, with a sampling replication of 60
photo-quadrants per station per time, the minimum change in the density of this species that could
be detected with 95 percent confidence for 80 percent of the time was approximately 70 percent.
This power analysis-to-effect comparison raises questions as to whether this effect in a single
species was a chance event. The sampling error was greater than the range of the effect detected.
Therefore, despite the time-space interaction and a relationship between dose and response, the
authors concluded that significant doubts remain as to whether there was a real platform-related
effect on this species.
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9-44
CAMP monitoring data has revealed several variables that may limit the ability of any
monitoring program to detect change related to oil and gas activity in the region. The densities and
numbers of species with transect location has been shown to vary along all isobaths. Potential
sources of hydrocarbons from natural seeps confound the ability to relate change to oil and gas
activities. Fishing activities risk in-situ instrument deployments and also affect bottom
communities. Finally, the difficulty of scheduling surveys to coincide with drilling activities for
appropriate before-and-after comparisons is a basic problem in any monitoring program, and it has
been shown in this program to be particularly difficult to control.
9.3.2 Synthetic-Based Fluids
Smith, J. and SJ. May. 1991. UlaWellsite 7/12-9 Environmental Survey 1991. A report to
SINTEFSIfrom the Field Studies Council Research Centre. November 1991.
This paper is the second in a series of three lead by Janet Smith, identifying the results of
yearly sampling at the Ula well site 7/12-9 in the North Sea. This paper also includes a
comparison of the 1990 to 1991 results. The authors report that sampling was conducted one year
after the discharge of an ester-based drilling fluid. The sample stations were along two transects,
one to the southwest (SW) and one to the southeast (SE), with distances from the discharge
location of 50, 100, 200, 500, 800,1,200,2,500, and 5,000 m to the SW and 100, 200, 500, and
1,200 m to the SE. A reference station was located 6,000 m to the northwest of the discharge
point. The ten replicate samples taken at this reference station were "treated as two sets of five
replicates to make data analysis easier," and are referred to as Ref. A and Ref. B. Samples were
taken for total hydrocarbon (THC), ester, metals, grain size analysis, and biological analysis.
THC reported for the 1990 samples were highest at 200 and 500 m to the SW and 100 and
200 m to the SE. These THC levels were reported at 774 and 86.4 mg/kg for the SW stations and
184 and 205 mg/kg for the SE stations, respectively. The THC levels for the 1991 survey were
dramatically reduced to 13.6, 5.9, 64.0, and 3.8 mg/kg for same stations listed above. Although
there was an increase in THC levels for the 50 and 100 m SW stations, it was not above
background levels measured at the reference station. There was an overall decreasing trend for
the THC concentration from 1990 to 1991.
The ester concentrations reported in 1990 were 85,300,46,400, and 208 mg/kg for the 50,
100, and 200 m SW stations, respectively. The reported ester values for these stations for 1991
dropped to 0.21, 0.22, and 1.34 mg/kg, respectively.
Barium concentrations for 1990 were reported highest at the 50-200 m SW and 100-200 m
SE stations. There was an increase in Ba concentration along the SW transect from 1,720 to 2,890
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9-45
mg/kg, out to 200 m. The Ba concentration decreased along the SE transect, with the highest level
of 3,770 mg/kg at 100 m. There was an overall decrease in 1991 Ba levels.
The authors also report dramatic changes in the benthic communities from 1990 to 1991 as
summarized in Exhibit 9-7. Although one station showed an increased abundance of the
opportunistic C. capitata, this isolated instance of taxonomic indicator of stress was not taken to
demonstrate any generalized impact had occurred from the discharge of this material.
Exhibit 9-7. 1990 and 1991 North Sea Benthic Community Data
Sample Station
SOmSW
100 m SW
100 m SE
Reference A
Reference B
Taxa
1990
4
7
35
66
53
1991
51
44
. 52
48
58
Individuals
1990
16
167
234
385
356
1991
379
370
405
340
329
Candler, John E., S. Hoskin, M. Churan, C. W. Lai, andM. Freeman. 1995. Sea-floor
Monitoring for Synthetic-Based Mud Discharged in the Western Gulf of Mexico. SPE
29694 Society of Petroleum Engineers Inc. March 1995.
The authors monitored the fate and effects of discharged SBF and associated cuttings
(SBF-cuttings). The authors measured the fate of the polyalphaolefin (PAO) on three sampling
cruises to an oil platform that had discharged SBF-cuttings consisting of 441 bbl of cuttings and
354 bbl of adhering SBF. The cruises were conducted nine days, eight months, and 24 months
after the discharge had stopped. The effects of the SBF and cuttings on the benthos were measured
only on the third sampling cruise. The sampling grid was a series of stations along two
perpendicular transects running in north/south and east/west directions from the discharge point.
The sampling stations were located along each of the transects at distances of 25 m, 50 m, 100 m,
and 200 m from the discharge point. Samples from 2,000 m were used as reference points. The
authors used chemical analysis for barium, total petroleum hydrocarbons (TPH) and oil and
grease (O&G) to determine the presence of PAO base fluid in sediment samples. The authors
stated that TPH was the better of the two organic analyses for detecting the synthetic material
because the TPH test excludes certain polar organic compounds (e.g., fatty matter from animal and
vegetable sources) often detected in O&G tests. Effects on the benthos were determined by a
community analysis system which measured the species richness (number of taxa), evenness (how
equally the total number of organisms is distributed), and diversity (measure of interaction of
richness and evenness).
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The authors indicated that the greatest initial distribution of TPH, as measured nine days
after discharge, was along the north/south transect with maximum values of 39,470 mg/kg (3.9
percent) at 100-m north and 134,428 mg/kg (13.4 percent) at 50-m south. In addition, TPH was
initially measured above 1,000 mg/kg in all four directions with the furthest locations of 100-m
south and 200-m north. The results from the second sampling survey (eight months later) indicated
a decrease in average TPH for all distances except at 25 m. There was an increase in average
TPH at 25 m predominately to the south and west (from 203 to 7,283 and 2,827 to 25,747 mg/kg,
respectively), indicating a southwesterly drift in the sediment. Results from the third and final
sampling survey (24 months later), while indicating a decrease in the average TPH at 25 m, also
indicated an increase in TPH at all but one of the four 25-m stations. The decrease of the west 25-
m station (from 25,747 to 8,330 mg/kg) overshadowed the increase of TPH at the other three
stations. Two stations beyond 25 m (50-m south and west) each measured an increase to greater
than 1,000 mg/kg TPH.
Although not discussed by the authors, the chemical analysis for the third survey indicated
an increase or no change in TPH for 10 of the 16 stations within 200 m of the discharge. There
was a slight increase in TPH for the 2,000-m west reference station. Sediment TPH and barium
data suggest little degradation of PAO (as indicated by TPH) between the second and third
surveys, although migration of fluids to farther stations may be occurring. Exhibits 9-8 and 9-9
present average PAO (as indicated by TPH) and Ba levels versus distance for these surveys.
The benthic analysis, at 24 months after SBF-cuttings discharge terminated, indicated three
sample stations that were significantly different than the reference stations. These three sample
stations were 25- and 50-m south and 25-m west from the discharge location. The highest TPH
values were also measured at these three stations. The variability for species richness, abundance,
diversity, and evenness was reported to be much higher among all sample stations within 200
meters of the discharge site than the variability among the reference stations.
Schaanning, M. 1995. Evaluation of Overall Marine Impact of the Novadril Mud System.
NIVA Report 0-95018.
This report reviews available laboratory data on the toxicity, bioaccumulation, and
biodegradability of three types of polyalphaolefin (PAO)-based SBF. The report compares the
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9-47
Exhibit 9-8. Sediment TPH vs. Distance from Drill Site
100 _ looo
Distance from Drill Site (meters)
I Sediment TPH are DtRECTlONALLY-AVERAGED fN. S. E. W) values fi
Exhibit 9-9. Sediment Barium vs. Distance from Drill Site
Distance from Drill Site (meters)
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9-48 ; :
finding of experimental studies on PAOs to field surveys of ester- and ether-based synthetic muds.
The author cites results of Smith and Moore (1990) and Smith and Hobbs (1993), in which three
surveys were conducted at the Ula well site 7/12-9 in the North Sea in 1990 immediately after
discharge of 97 tons of synthetic esters ceased, in 1991 one year later, and in 1992 two years later.
Sampling pattern information for these surveys is given in the summary of Smith and May (1991).
Schaanning reports that during the 1990 survey, the maximum concentration of synthetic
ester detected was 85,300 mg/kg at 50 m from the well. The average concentration of synthetic
ester for eight sample sites (between 0 and 1 km; no further detail provided) was 16,546 mg/kg
compared to 2.3 mg/kg at a reference station 5,000 meters distant. Benthic organisms were
severely impacted out to 100 m. Schaanning reports that in 1991 and 1992, the maximum
concentrations of synthetic ester base fluid were 11.7 and 0.38 mg/kg, respectively. In 1991, the
average ester concentration at eight stations within 1,000 m of the drill site was 2.5 mg/kg,
approximately 10-fold higher than that at a reference station 6,000 m distant from the drill site. In
1992, the average ester concentration at eight stations within 1,000 m was 0.24 mg/kg,
approximately 3-fold higher than at the reference station 6,000 m distant. Schaanning reports other
multivariate analyses of benthos (Smith and Hobbs, 1993) provided evidence that minor changes
to the macrobenthic communities were still present two years after the discharge ceased.
Schaanning also cites a three-year study by Bakke et al. (1992) of a discharge of cuttings
contaminated with an ether-based SBF. The surveys were conducted at the Gyda well site 2/1-9,
just after the discharge of 160 tons of ether SBF ceased and annually for the next two years.
Bakke reports mat the maximum concentrations of synthetic ether at 50 m southwest from the
platform were 2,600,14,700, and 3.7 mg/kg for 1991, 1992, and 1993, respectively. The mean
concentrations for the stations between 100 and 200 m from the platform for 1991, 1992, and 1993
were 236, 96, and 2.1 mg/kg ether, respectively. Although no benthic data are presented for the
four stations at which benthic biota were analyzed, Bakke reports benthic impacts were
"remarkably weak" for the-high concentration of synthetic ether detected in 1992.
It should be noted that Schaanning includes brief discussions of additional seabed studies,
which are not referenced to studies or reports, from the North Sea. The information presented
from these studies is limited and does not include any quantitative results from benthic analyses.
Daan, R., K. Booij, M. Mulder, andE. Van Weerlee. 1996. Environmental Effects of a
Discharge of Cuttings Contaminated-with Ester-Based Drilling Muds in the North Sea,
Environmental Toxicology and Chemistry, Vol. 15, No. 10, pp. 1709-1722. April 9
1996.
The authors conducted field surveys in the Dutch sector of the North Sea for the effects of
discharged drill cuttings contaminated with an ester-based fluid over an 11-month period. A total
of 181 metric tons of ester (in a total estimated amount of 477 tons of an ester-based SBF) was
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9-49
discharged. Three sampling surveys were conducted 1,4, and 11 months after the drilling was
completed. The authors also conducted a background survey prior to drilling to determine natural
variations of macrofauna and background chemistry. This background survey was conducted prior
to platform placement along a northeast-southwest transect that followed local residual current
patterns, with station located from the well site at distances of 75, 200, 500, 1,000, and 3,000 m to
the NE, and 75 m to the SW. However, because of the changes in sediment type beyond 200 m,
this transect was not used in the post-drilling surveys. The first post-drilling survey was
conducted one month after ester-based SBF discharges ceased to determine ester base fluid
concentrations only and was sampled northward from the drill site at distances of 75, 125, and 200
m to the N, then 75 m to the NE of the well site. There were no benthos samples taken during this
survey. The second and third post-drilling surveys occurred four and 11 months after ester-based
SBF discharges ceased. Both surveys included benthos and chemistry samples taken at 75,125,
200, 500, 1,000, and 3,000 m to the N, at 75, 125, and 200 m.to.the NE, and at 75 m to the SW.
The chemical analysis for the three post-drilling surveys indicated the ester base fluid was
confined to distances under 200 m from the well site. Once beyond the 200 m station, ester base
fluid concentrations were at background levels. However, the analysis also showed an increase in
the ester base fluid from the one- to four-month surveys for all distances out to 200 m. Analyses
from the 11-month survey indicated a sharp decline in ester base fluid at all stations.
Sediment grain size distributions and benthic macrofaunal abundance from the background
survey indicated similar communities occurred only out to 200 m. As a result, benthos background
results used for analysis were limited to stations at 75, 125, and 200 m from the discharge
location. The benthic analysis from the second survey indicated effects out to 500 m from the well
site and was attributed to the echinoderm Echinocardium cordatum. Ecordatum is highly
sensitive to organic enrichment and living adults were found up to 500 m from the well site.
Additionally, a bivalve that was one of the dominant species at 500 m was not found at the closer
stations. There was a gradual increase in species abundance with distance. When compared to the
background levels, the species abundance beyond 500 m after four months was lower, but the
authors attributed this to seasonal fluctuations. Benthos analysis from the third post-drilling survey
at 11 months indicated significant impacts out to 200 m. The authors indicate that species
abundance, while significantly different from the reference stations, showed recovery of the
sediments was apparent after 11 months.
BP Exploration Operating Company Ltd. 1996. BP Single well 15/20b-12 (Donan) synthetic
mud (Petrofree) second post-drilling environmental survey. Environment & Technology
Ltd. ERTDraft Report No. 96/062/3 June 1996.
This survey was the second of two surveys at the BP single well site 15/20b-12, located in
the North Sea. Although the first survey was not available for review, this second report
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9-SO _^ '
compared the 1995 and 1996 seabed survey results for this well site. The first survey was
conducted in August 1995 approximately 5 months after drilling shutdown. The second survey
was conducted in June 1996,15 months after drilling shut down. The discharge of Petrofree, an
ester SBF, amounted to 304 metric tons and was discharged at a depth of 142 m. The observations
taken by the authors were: 1) Side-scan sonar for cutting depth (piles), 2) Petrofree base fluid
concentrations in 0-2 cm, 2-5 cm, and 5-10 cm of sediment, 3) barium concentrations, 4) redox
measurements at 2 cm and 4 cm, and 5) biota. Sampling sites were at 25-5,000 m down-current
(South) from the platform, 25-200 m up-current to the North, and 25-100 m to the East, West,
Northeast Northwest, and Southwest. ; .
The 1995 survey indicated the highest concentration of Petrofree in the surface sediment
(0-2 cm) was located within 25 meters of the platform. The sampling point with the highest
concentration was 25 m Southwest, with an ester concentration of 8,389 mg/kg. Concentrations
within 25 meters of the platform ranged from 1,055 to 8,389 mg/kg. The highest concentration at
the furthermost station was 105.5 mg/kg at 200 meters north of the platform. The concentrations of
Petrofree (base fluid) within 2-5 cm of sediment within 25 m ranged from 8.4 to 1,935 mg/kg. The
concentrations of Petrofree within 5-10 cm of sediment within 25 m ranged from 0,9 to 105.3
mg/kg. Petrofree was measured at a concentration of 1,081 mg/kg in 10-15 cm subsurface
sediment at 25 meters north. Barium concentration ranged from 70,100 mg/kg at the center to 661
mg/kg at 1,200 m south. Redox and side-scan sonar results for 1995 were not reported. Although
data are not given for effects on benthic communities for the 1995 survey, the report indicated that
the number of species, evenness, and diversity were statistically significant in relation to Petrofree
concentration and distance.
The 1996 survey indicated lower concentrations for surface sediment (0-2 cm) for most
sample sites. The authors reported changes ranging from 1.1-fold lower concentrations to 13.5-
fold lower concentrations from 1995 to 1996. Sediment concentration of Petrofree ranged from
133.1 to 1,785 mg/kg for the 25 m range: The highest concentration at the furthermost point was
0.1 mg/kg measured at 500 m south. Variability among subsurface sediment (2-5 and 5-10 cm)
Petrofree concentrations prevented development of trends for subsurface concentrations. Barium
concentration ranged from 22,000 at the center to 572 mg/kg at 1,200 m south. Redox readings
indicated anaerobic conditions within 200 meters of the platform. The depth profile indicated
cutting piles of up to 15 cm out to 50 meters from the platform. Biota measurements indicated
clear impacts at 50 m, with transition communities developing between 100 to 300 m. The authors
stated the benthic communities at 1,200 meters indicated impacts associated with industrial
activity and trace amounts of Petrofree were measured at that location.
Vik, EA., S. Dempsey, B. Nesgard. 1996. Evaluation of Available Test Results from
Environmental Studies of Synthetic Based Drilling Muds. OLF Project, Acceptance
Criteria for Drilling Fluids. Aquateam Report No. 96-010.
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9-51
The authors provided a summary of results from eleven seabed studies, three of which have
been separately reviewed in this report. Many of these reports were unavailable in English. The
authors presented a short review of sampling grids, discharge volumes, discharge depths, and
results. The information provided by authors was limited for each seabed survey and the results
are included in Exhibit 9-2. However, a critical review of each original report has not been
provided in this Environmental Assessment. The overall trends of these reports were: (1)
concentrations decreased with distance from discharge point; (2) concentrations measured were
not discharge volume dependent; and (3) concentrations decreased with tune, although there were
a few instances where the concentrations actually increased.
Continental Shelf Associates, Inc. 1998. Joint EPA/Industry Screening Survey to Assess the
Deposition of Drill Cuttings and Associated Synthetic Based Mud on the Seabed of the
Louisiana Continental Shelf, Gulf of Mexico. 21 October 1998, Data Report. Prepared
for API Health and Environmental Sciences Dept.
The authors provided a data report on a joint EPA/Industry screening cruise, which was
conducted to provide a preliminary evaluation of the area! extent of observable physical,
chemical, and biological impacts of drill cuttings contaminated with SBFs (SBF-cuttings) and to
evaluate sampling methods that will be used in future more detailed surveys. Three sites were
surveyed for organics (SBF associated hydrocarbons, TOC and PAH), sediment grain size, odor
and visual characteristics, and water column profiles. Oxidation-reduction potential, macrofauna
and sediment toxicity samples were taken at selected sites. Side-scan sonar and Benthos
MiniROVER remote operated vehicle (ROV) television camera were used to identify
accumulation of drill cuttings. Sampling sites were located on a radial grid and along four
transects that were parallel with bathymetry when possible. The stations were at distances of 50,
150, and 2000 m from the platform, with the 2000 m stations serving as the references stations.
Two additional stations, 100 m from the platform, were sampled at two of the sites. The highest
concentration of SBF associated hydrocarbons (1,900, 6,500, and 23,000 mg hydrocarbon/kg dry
sediment) were found within 50 m of the platforms. The furthermost station at which SBF-
associated hydrocarbons were found was 100 m for one platform. The concentration measured at
that one station was 41 mg hydrocarbons/kg dry sediment. Nine sediment samples were also taken
for sediment toxicity tests using the 10-day sediment toxicity test (ASTM E 1367-92; ASTM,
1992). Two of the nine sediment samples taken would have been considered toxic to marine
amphipods using the current sediment testing guidelines. Percent survival of amphipods exposed
to those two samples was 77% and 62%. SBF associated hydrocarbons were not measurable at
the detection level for these two samples. Analyses of impacts to marcofauna were not complete
at the time of this report. Conclusions drawn by the authors were elevated concentrations of SBF-
associated hydrocarbons were scattered around the platform rather than in a continuous pattern;
side-scan techniques could be improved; ROV use is not appropriate near soft muddy seafloors;
and a better methodology for evaluating electrochemical potential (Eh) is needed.
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9-52
Fechhelm, R.G., B.J. Galloway, andJM. Farmer. 1999. Deep-water Sampling at a Synthetic
Drilling Mud Discharge Site on the Outer Continental Shelf, Northern Gulf of Mexico.
Presented at the 1999 SPE/EPA Exploration and Production Environmental Conference Feb. 28
- March 3,1999. SPE 52744
The authors conducted two benthic studies to assess the impacts of the discharge of drill
cuttings contaminated with the SBF Petrofree LE (a 90% LAO/10% ester blend) on benthic
communities in 565 meters water depth. The studies were conducted 9 months apart with the first
(July 1997) conducted 4 months after discharge ceased. Prior to this July survey, 6,263 bbls of
SBF had been discharged. An additional 1,486 bbls of SBF was discharged for 2 months prior to
the second survey in March of 1998. The surveys analyzed benthic sediment samples for both
chemical concentrations of Petrofree LE and changes in benthic communities along four transects
(ME, SE, SW, and NW). Sampling stations were located at 25 m intervals with the SW and NE
transects extending to 75 m and the NW and SE transects extending to 50 m. As a result of
chemical analyses from the July 1997 survey, the NW transect was extended to 90 m during the
March 1998 survey. Samples for chemical analysis were divided into surficial samples (0-2 cm)
and subsurface samples (2-5 cm).
Chemical analyses results for both surveys indicate the highest concentration of SBF for
both surficial and subsurface samples were found along the NE transect and were located at the 75
m station. Concentrations of SBF at this location for the surface samples were 165,051 mg/kg for
1997 and 198,320 mg/kg for 1998. Concentrations at these locations for subsurface samples were
8,332 mg/kg for 1997 and 85,821 mg/kg for 1998. The authors suggest the possible reasons for
high concentrations of SBF may be due to slower biodegradation rates than those noted in the
North Sea or the initial concentration of Petrofree LE was higher than that measured. There were
no statistical differences between the July 1997 and March 1998 surficial and subsurface
concentrations. However, the March 1998 values were higher, lending some weight to the
hypothesis that the initial Petrofree LE concentration was higher than measured.
Results of the March 1998 benthic survey indicate an increase of polychaetes and
gastropods as compared to MMS background data. Polychaete densities were nearly 40 times
higher than background data. Gastropod densities were nearly 3,000 times higher than
background. The authors postulated that biodegradation may have sustained bacterial activity at a
level that lead to an increase in these benthic macrofauna.
Unocal Comments, EPA Effluent Limitations Guidelines for the Oil & Gas Extraction Point
Source Category, Proposed Ruling (40 CFR Part 435), June 9, 2000.
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- ; 9-53
Unocal submitted public comments to EPA, including seabed survey data from 4 wells
drilled from the Vermillion 38/39 platforms. The platforms were located in shallow Gulf of
Mexico waters (35-40 feet). The surveys consisted of collecting sediment samples from a
minimum 9 meters to a maximum of 86 meters distance from the discharge point. According to the
laboratory reports presented in Appendix C of the comments, the sediment core samples had
experienced some mixing, so composite samples were taken from each of the cores as opposed to
samples from the top, middle, and bottom sections of each of the cores. The samples were
analyzed for total oil and grease and the hydrocarbons were classified using gas chromatography
analysis.
Of the four surveys, a small area of sediment around Structure M had significantly elevated
total oil and grease levels (ranging from 140 to 6,000 ppm) at approximately 40 meters from the
discharge point. Total oil and grease levels in most of the other sites were near the detection limit
of 50 ppm as described in the laboratory report.
In addition, Unocal submitted a videotape of seafloor site surveys conducted with an ROV
before and immediately after drilling four Unocal deep water wells. The wells were the
following: South Sierra, located in 1,120 m water depth, Bowshock, in 762 m water depth,
Sumatra, 1,133 m water depth, McKinley, 854 m water depth. The videotapes do not show any
evidence of cuttings pile formation beneath any of the four well locations. According to Unocal,
this is expected because of the water depth involved, allowing the cuttings to be carried away by
currents and become dispersed.
Neff, J.M, McKelvie, S., andAyers, R.C. A Literature Review of Environmental Impacts of
Synthetic Based Drilling Fluids. Report to U.S. Dept of the Interior, Minerals Management
Service, Gulf of Mexico OCS Office. April 27, 2000.
Most of the seabed surveys of SBF discharges reviewed in this report were also reviewed
by EPA and are summarized above. There are, however, several UKOOA unpublished report data
that the authors reviewed and presented in their report. As part of the SBF.cuttings discharge
studies in the UK Sector, seabed surveys were performed to document the presence of cuttings
piles on the seabed near single-well drilling operations. According to the authors, the height and
area of cuttings piles varied widely, ranging from not evident to 3 m in height and to 0.9 km2.
The authors summarized UKOOA well data on SBF concentrations in sediments from 17
sites. Surveys were conducted shortly after discharge (year 1) and one year later (year 2).
According to the authors, there was a large variation in the data and it was not possible to draw
any firm conclusions about rates of biodegradation, dilution, or washout of different types of SBF
cuttings from sediments. Despite this variation, the authors stated that the average concentrations
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9-54
in sediments of n-parrafins, linear paraffins, LAOs, and ester SBFs declined between the Year 1
and Year 2 surveys, suggesting some degradation or washout of these SBFs. Ester concentrations
in sediments near rigs using ester SBFs were lower than concentrations of other SBFs near the
platforms using other SBFs. This observation lends support to the hypothesis that esters
biodegrade rapidly in sediments.
The authors conducted a regression analysis to determine the relationship between water
depth and maximum concentrations of SBF base chemical in surface sediments near drilling
platform in the UK Sector of the North Sea. There was no correlation with the mass of cuttings
discharged. The amount of cuttings accumulating in sediments is dependent on a complex
interaction of discharge rate and mass, water depth, current structure of the water column, and the
type of SBF and cuttings.
Two UK North Sea well site SBF sediment concentration data was provided by the authors
in full, including all transects and different sediment depths. One well was drilled with an ester
SBF in a water depth of 150 meters. Samples were collected soon after discharge along five
transects at varying distances from the discharge point, 3 locations from 0 to 75 meters for each
transect. All transects contained elevated ester concentrations in the surface sediments though the
southwest transect was most elevated (see Table 9-2). Ester concentrations in the surface
sediments during the second year after discharge decreased significantly for most sampling
locations except the furthest from the discharge point (75 m). In deeper sediments (2-5 cm), the
ester concentration was elevated in the second year compared to the first year in most of the
sampling points.
The other well was drilled using an LAO SBF in 185 meters of water. Samples were
collected soon after discharge along seven transects, but only the southeast transect was sampled
in more than one point other than the discharge location (0, 50m, and 100 m). In most cases, SBF
cuttings do not penetrate and mix deeply into surface sediments near the platform. However, at
this site, the concentration of LAO in sediments at the well site (0 meters from the discharge)
during the first year of sampling increased from 7,876 mg/kg at the surface to 25,023 mg/kg at a
sediment depth of 5 to 8 cm.
Of the two UK North Sea wells studies described above, the one drilled with an ester also
sampled seabed biologic communities. According to the authors, the numbers of individuals of
benthic fauna were not correlated with sediment ester concentrations. In fact, highest abundances
of benthic fauna were in sediments with the highest ester concentrations. However, the sediments
with the highest concentrations of esters and largest numbers of benthic animals had the fewest
taxa, indicating that the surviving fauna of ester-contaminated sediments consisted of a few
opportunistic species. A year after drilling, the pattern had not changed, although the maximum
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9-55
concentration of ester in sediment had decreased. The two most heavily contaminated sediments
had the lowest numbers of taxa, but some of the largest numbers of individuals.
The authors also present data of benthic faunal surveys performed shortly after completion
of drilling with linear paraffin SBFs on two platforms in the UK Sector of the North Sea. At the
first platform, the number of individuals of benthic fauna in sediments declined with increasing
linear paraffin concentrations in sediments. At the second linear paraffin discharge site, the
benthic fauna were much less abundant and diverse in sediments compared to the first discharge
site. The number of individuals was highest in sediments from three or the four stations with the
highest linear paraffin concentrations. The authors concluded that the naturally low biological
diversity of the benthic fauna at the second site may have obscured effects of the drilling
discharges, or the resident community, possibly already adapted to environmental stress, may have
been less sensitive to SBF cuttings than the community at the first site.
Jensen, T., etal Technical Report: Dispersion and Effects of Synthetic Drilling Fluids on the
Environment; Biological survey, Long-term Effect of Oil and Produced water, Chemicals and
Oil Spill Contingency. Prepared for the Ministry of Oil and Energy. Report no. 99-3507.
September 7, 1999.
This study was based on previously collected field data from biological and chemical
surveys of the oil and gas fields in the North Sea and the Norwegian Sea. In these areas, there
were relatively few fields where only SBFs were used and data from surveys were limited to the
time period 1993 to 1997. There was only one field (the Tordis field) that had coinciding
chemical and biological data over several years. EPA reviewed the Tordis chemical data only
(see Gjos, et al., 1995). In total, this study compares the following fields and years: Balder 1997,
Froy 1997, Heidrun 1997, Snor 1996, Statfjord North 1996, Statfjord East 1996, Tordis 1993-
1997, Vigdis 1996 and Yme Gamma 1996.
The authors used the sediment concentration of barium as an indicator sedimentation effects
and sediment concentration of metals and organic compounds as indicators of whether toxic effects
are likely. To assess the possible effects of cuttings on the benthic fauna, correlations were made
between the diversity of the benthic fauna and the percentage of barium in the sediment and
between diversity and quantity of SBFs.
The maximum reduced diversity on stations closest to the discharges, compared with
unaffected stations and reference stations around the respective installations, was 50% on Satfjord
North in 1996, but there was clearly reduced diversity on the Tordis field in 1995 (44%) and the
Snorre field in 1996 (36%). In most stations, reduced diversity was only found at 250 meters from
the platform, but on Snorre, Statfjord North, and Statfjord East, reduced diversity was also found
at 500 meters (see Exhibit 9-10). A change in the density of individuals in indicator species
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9-56
(Chaetozone setosa, Capitalla capitata, Pseudopolydora paucibranchiata, Raricirrus beryli,
and Octobranchus floriceps) was found up to 1,000 meters from the platform in some fields, but in
most cases only in stations up to 500 meters.
According to the authors, in several of the fields a statistically significant correlation was
found between reduced diversity in the benthic fauna and high concentrations of barium, olefin and
ester in the bottom sediments. In most cases, there was a stronger correlation between the
reduction in diversity and high concentrations of olefin and/or ester than with barium, which may
indicate that possible toxic effects are greater than effects due to sedimentation and physical
disturbance as a result of dispersion of cuttings. In addition, the authors concluded through their
statistical analyses of fields using both ether and olefins and fields using both esters and olefins
that ethers have less environmental impacts than olefins and olefins have less impacts than esters.
The authors also stated that in more than half the fields, there was a significant, positive
correlation between the number of individuals of several pollution tolerant bristle worm species
and negative correlation in density of individuals of he bristle worm, Myriochele oculata and the
mussel, Thyasira succisa.
A final analysis conducted in this report was a correspondence analysis, specifically the
canonical correspondence analysis (CCA). This analysis is an ordination method that analyzes the
species matrices consisting of many species compared in relation to the number of stations.
Environmental variables are then analyzed together with fauna data and the linear combinations of
the environmental variables are chosen.. Mathematically, this means that the range of Variation for
the species is projected down in the range of variation for the environmental variables. The linear
combinations are determined on the basis of regression. According to the authors, the CCA
analyses show that there is a correlation between discharge of SBFs and biological variation in the
benthic community. Specifically, copper, sediment olefin concentration and sediment ester
concentration best explain the observed variation in benthic fauna.
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9-57
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Orentas, N., Avanti Corporation, Memorandum to Charles Tamulonis, USEPA, BAD, regarding,
"Preliminary Analysis ofBenthic Faunal Sample Data Collected During the EPA/Industry SBF
Screening Cruise, August 1997." December 17, 2000.
In August 1997, a team of EPA and Industry environmental scientists sampled three central
Gulf of Mexico oil and gas platforms as a preliminary investigation of the effects of cuttings from
SBFs on the local benthic environment. SBF sediment concentrations were analyzed and are
reported in CSA, 1998 (see summary above). Grab samples for macroinfaunal analysis were
collected at the Grand Isle (GI) 95A and South Marsh Island (SMI) SVC platforms. During the
survey, 100-m stations were added along the east and west transects at GI 95A and SMI 57C for
additional collections of macroinfaunal and toxicity samples.
EPA conducted a preliminary analysis of the macroinfaunal data (see Exhibit 9-12). The
number of species and number of individuals per species for each grab sample collected around
SMI 57C platform do not vary significantly. Therefore, it appears that there are no detected
impacts to the fauna in this location. For samples collected at GI 95 A, both the number of species
and the number of individuals appear to be depressed at 50 meters along the western transect and
possibly at 150 meters, though the variability between the grab samples is too high to consider the
depression significant at the 150 meter location. .
Jacques Whitford Environment Limited. 1999a. "Hibernia Production Phase Environmental
Effects Monitoring Program - Year One, Volumes I & II." Prepared for Hibernia Management
Development Corporation. July 1999.
The Hibernia field is located near the northeast corner of the Grand Banks, approximately
315 km east-southeast of St. John's, Newfoundland, and approximately 35 km northwest of the
Terra Nova Oil Field. Drilling commenced in June 1997 from the Hibernia platform. This report
is part of an ongoing Environmental Effects Monitoring (EEM) program. The EEM consists of two
sampling programs: a sediment survey and a biological survey.
Sediment sampling was based on a sampling grid consisting of 44 sampling points laid out
in a series of eight radii and concentric rings progressing outward from the platform location. The
closest ring to the platform is 250 meters, the furthest is 8,000 meters and two reference stations '
were located 16 km north and west of the platform. For the second survey, five stations were
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9-60
added along a southeast transect starting at about 2,000 meters from the Hibernia platform.
Samples were collected for analysis of sediment chemistry, sediment toxicity, and benthic infauna.
Benthic data was also collected to within 250 meters of the platform.
A baseline biological survey was conducted from December 4 to 6, 1994 within a fishing
zone (500 to 2,000 meters) around the platform and at a reference site located approximately 50
km northwest of the platform. The biological survey specifically targeted the collection of
American plaice and Iceland scallops. Samples were tested for body burden and
organoleptic(taste panel) evaluations. According to the authors, problems occurred in collecting
sufficient samples for the biologic analyses.
The first post-production sediment survey was undertaken in August of 1998, while the
first post-production biological survey was conducted in December 1998. According to the EEM
program, surveys are to be conducted on an annual basis for the first three years of production
(1998,1999. And 2,000) and every second year thereafter.
The Hibernia platform uses water based muds, oil based muds (DBFs) and SBFs for
drilling. The OBFs used are low-viscosity mineral oils or paraffin oils. The SBF used contains
the base oil IPAR-3, a synthetic iso-alkane. According to the study authors, the OBF solids are
treated by a cuttings wash system and discharged through shale chutes at the platform. SBF
cuttings are not cleaned and like the OBF cuttings are discharged onsite. Though low-viscosity
mineral oils are significantly less toxic than diesel-based OBFs, nevertheless they are not
considered SBFs. Thus, the data presented in the Hibernia report may not represent effects from
SBF discharges alone, since both an SBF and OBF are being discharged from the same location.
However, EPA considered the survey data valuable and thus, reviewed the findings and
summarized them in Exhibit 9-2.
Sediment chemistry analysis consisted of analyses for trace metals, trace organics, such
PAH and TEH, and sediment properties, such as TOC. The study did find that, relative to the
baseline survey, there was a significant increase in the level of sediment TEH concentrations at the
250 meter and 500 meter locations and that concentrations attenuated with distance from the
platform. Among the study recommendations, one is that a more intensive sampling program
should be conducted within the 1,000 meter range. For a more accurate assessment of discharge
impacts that is not considered by the study authors, t sampling should probably be conducted at
even closer locations to the platform, such 25, 50 and 100 meters.
A review of the summary of benthic infaunal data suggests that there is no statistical
difference in either the abundance or richness beyond 250 meters from the platform.
-------
10-1
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-------
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-------
10-10
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-------
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-------
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Houston, Texas, May 21-23,1975.
-------
APPENDIX 3-1
CALCULATION OF
GULF OF MEXICO SHRIMP CATCH
A-l
-------
-------
Calculation of Gulf of Mexico Shrimp Catch
Landings (Ibs)
CatchrLandings Ratio
Catch (Ibs)
Catch by Location (Ibs)
0-3 miles
Coastal
Offshore
3-80 miles
Offshore Area (mi2)
0-3 mile
3-80 mile
Catch/Area (lbs/mi2)
0-3 mile
Weighted Average
Catch (Ibs)
Texas
70,753,261
0.85
60,140,272
34,640,797
23,555,742
11,085,055
25,499,475
1,107
28,413
10,014
Louisiana
85,743,137
1.23
105,464,059
60,747,298
45,864,210
14,883,088
44,716,761
1,314
33,726
11,327
10,850
Source/Comment
NMFS, 1999/Average of
1997-1998 landings
Offshore Environmental Assessment,
Table 3-9 (Avanti, 1993)
Landings * Catch/Landings ratio
Offshore Environmental Assessment,
Table 3-9 (Avanti, 1993)/catch * 0.576
= 0-3 mile portion of catch,
0-3 mile portion * 0.668 (TX) or
0.755 (LA) determines protion of 0-3
mile segment that is offshore (as
opposed to coastal)
Offshore Environmental Assessment,
Table 3-1 1 (Avanti, 1993)
Assumes all shallow wells drilled are
in the Territorial Seas (0-3 miles);
weighted by total catch/state
A-2
-------
-------
APPENDIX 4-1
GULF OF MEXICO
SURFACE WATER QUALITY ANALYSIS
A-3
-------
-------
Water Column Pollutant Concentrations - COM
Baseline
Pollutant Name
,
Naphthalene
Fluorene
3henanthrene
3henol
PJidriJIIPJ^uta'n&IMeliJs^^
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc _ _^_
Aluminum
Barium
Iron
Tin
Titanium
Alkylated benzenes
Alkylated naphthalenes
Alkylated fluorenes
Alkylated phenanthrenes
Alkylated phenols
Total biphenyls
Total dibenzothiophenes
Average Cone. Of
Pollutants in Model
SBF Well Effluent
(mg/l)
1.0995
0.5997
1.4225
0.0039
0.1610
0.0146
0.8342
1.0391
0.1024
35.1248
2.7368
5.1370
1.9758
0.1610
0.1024
0.1756
29.3439
1327.4109
86055.8132
2245.6908
2.1368
12.8059
6.1896
58.1899
7.0046
8.8500
0.0341
11.5027
0.4902
Water Column
Cone. At 100
meters (mg/l)
2.94E-05
1.60E-05
3.80E-05
1.03E-07
4.73E-07
7.04E-09
2.90E-06
1.39E-07
3.56E-07
3.19E-05
4.61 E-07
2.75E-06
2.27E-06
5.59E-07
3.56E-07
6.10E-07
3.21 E-06
4.61 E-03
4.83E-03
7.80E-03
7.42E-06
4.45E-05
1.65E-04
1.55E-03
1.87E-04
2.36E-04
9.12E-07
3.07E-04
1.31E-05
Water Column
Exceedances of
Federal Criteria
0
0
0
0
0
0
0
0
0
. 0
0
0
0
0
A-4
-------
Water Column Pollutant Concentrations - GOM
BAT Option 1
Pollutant Name
Priority Pollutant Organics
Naphthalene
Fluorene
3henanthrene
Phenol
Priority Pollutants; Metals
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
.ead
Nickel
Selenium
Silver
fhallium '
Zinc
Non-Conventional Pollutants
Aluminum
Barium
ran
In
"rtanium
Alkylated benzenes
Alkylated naphthalenes
Alkylated fluorenes
Alkylated phenanthrenes
Alkylated phenols
btal biphenyls
Total dibenzothiophenes
Average Cone. Of
Pollutants in Model
SBF Well Effluent
(mg/l)
0.4987
0.2720
0.6451
0.0018
0.0730
0.0066
0.3783
0.4712
0.0465
15.9289
1.2411
2.3296
0.8960
0.0730
0.0465
0.0796
13.3072
601.9718
0.0730
1018.4055
0.9690
5.8074
2.8072
26.3908
3.1768
4.0137
0.0155
5.2168
0.2223
Water Column
Cone. At 100
meters (mg/l)
1.33E-05
7.27E-06
1.72E-05
4.69E-08
2.15E-07
3.19E-09
1.31E-06
6.30E-08
1.61E-07
1.45E-05
2.09E-07
1.24E-06
1.03E-06
2.54E-07
1.61E-07
2.77E-07
1.46E-06
2.09E-03
4.10E-09
3.54E-03
3.37E-06
2.02E-05
7.50E-05
7.05E-04
8.49E-05
1.07E-04
4.13E-07
1.39E-04
5.94E-06
Water Column
Exceedances of
Federal Criteria
0
0
0
0
0
0
0
0
0
0
0
0
0
0
A-5
-------
Water Column Pollutant Concentrations - GOM
BAT Option 2
Pollutant Name
iIKH»ufan.t;g
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc •
Aluminum
Barium
Iron
Tin
Titanium
Alkylated benzenes
Alkylated naphthalenes
Alkyiated fluorenes
Alkylated phenanthrenes
Alkylated phenols
Total biphenyls
Total dibenzothiophenes
Average Cone. Of
Pollutants in Model
SBF Well Effluent
(mail)
0.4750
0.2591
0.6145
0.0017
0.0696
0.0063
0.3604
0.4489
0.0443
15.1752
1.1824
2.2194
0.8536
0.0696
0.0443
0.0759
12.6776
573.4885
37179.1542
970.2178
0.9232
5.5326
2.6738
25.1368
3.0259
3.8230
0.0147
4.9689
0.2117
Water Column
Cone. At 100
meters (mg/I)
1.27E-05
6.92E-06
1.64E-05
4.47E-08
2.04E-07
3.04E-09
1.25E-06
6.00E-08
1.54E-07
1.38E-05
1.99E-07
1.19E-06
9.81 E-07
2.42E-07
1.54E-07
2.64E-07
1.39E-06
1.99E-03
2.09E-03
3.37E-03
3.21 E-06
1.92E-05
7.14E-05
6.72E-04
8.09E-05
1.02E-04
3.94E-07
1.33E-04
5.66E-06
Water Column
Exceedances of
Federal Criteria
0
0
0
0
0
0
0
0
0
0
0
0
0
0
A-6
-------
-------
APPENDIX 4-2
COOK INLET, ALASKA
SURFACE WATER QUALITY ANALYSIS
A-7
-------
-------
Water Column Pollutant Concentrations - AK
Baseline (Zero Discharge) ;{
Pollutant Name
Bliij|jpl^llitiiiii!SiW*e!^;I
Naphthalene
Fluorene
Phenanthrene
Phenol
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Aluminum
Barium
Iron
Tin
Titanium
Alkylated benzenes
Alkylated naphthalenes
Alkylated fluorenes
Alkylated phenanthrenes
Alkylated phenols
Total biphenyls
Total dibenzothiophenes
Average Cone. Of
Pollutants in
Model SBF Well in
Effluent (mg/l)
0.0000
0.0000
0.0000
0.0000 ,
-
o.oooo —
0.0000 __.
o.oooo -
0.0000
0.0000
0.0000
0.0000
o.oooo -
0.0000
0.0000 „
0.0000
0.0000 .
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
o.oooo - -
0.0000
0.0000
0.0000 -
0.0000
Water
Column
Cone. At 100
meters (mg/l)
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
Water Column
Exceedances
of Federal
Criteria
0
0
0
0
0
0
0
0
0
• o
0
0
0
0
Water Column
Exceedances
of AK State
Standards
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
A-8
-------
Water Column Pollutant Concentrations - AK
BAT Option 1
Pollutant Name
Priority Pollutant Organics
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metals
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc ,———,-,-««,„.««.
^on-Conventional Pollutants
Aluminum
Barium
ran
Tin
Titanium
Alkylated benzenes
Alkylated naphthalenes
Alkylated fluorenes
Alkylated phenanthrenes
Alkylated phenols
Total biphenyls
Total dibenzothiophenes
Average Cone. Of
Pollutants in Model
SBF Well in
Effluent (mg/l)
0.4987
0.2720
0.6451
0.0018
0.0730
0.0066
0.3783
0.4712
0.0465
15.9289
1.2411
2.3296
0.8960
0.0730
0.0465
0.0796
13.3072
601.9718
0.0730
1018.4055
0.9690
5.8074
2.8072
26.3908
3.1768
4.0137
0.0155
5.2168
0.2223
Water
Column Cone.
At 100 meters
(mg/l)
5.22E-05
2.85E-05
6.75E-05
1.84E-07
8.41 E-07
1.25E-08
5.15E-06
2.47E-07
6.32E-07
5.67E-05
8.19E-07
4.88E-06
4.03E-06
9.94E-07
6.32E-07
1.08E-06
5.71 E-06
8.19E-03
1.61E-08
1.39E-02
1.32E-05
7.90E-05
2.94E-04
2.76E-03
3.33E-04
4.20E-04
1.62E-06
5.46E-04
2.33E-05
Water Column
Exceedances
of Federal
Criteria
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Water Column
Exceedances
of AK State
Standards
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
A-9
-------
Water Column Pollutant Concentrations
BAT Option 2
• AK
Pollutant Name
Naphthalene
Fluorene
Phenanthrene
Phenol
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc | >w_ _ sj ^_
Aluminum
Barium
Iron
Tin
Titanium
Alkylated benzenes
Alkylated naphthalenes
Alkylated fluorenes
Alkylated phenanthrenes
Alkylated phenols
Total biphenyls
Total dibenzothiophenes
Average Cone. Of
Pollutants in Model
SBF Well in
Effluent (mg/l)
0.4750
0.2591
0.6145
0.0017
0.0696
0.0063
0.3604
0.4489
0.0443
15.1752
1.1824
2.2194
0.8536
0.0696
0.0443
0.0759
12.6776
573.4885
37179.1542
970.2178
0.9232
5.5326
2.6738
25.1368
3.0259
3.8230
0.0147
4.9689
0.2117
Water Column
Cone. At 100
meters (mg/l)
4.97E-05
2.71 E-05
6.43E-05
1.75E-07
8.01 E-07
1.19E-08
4.91 E-06
2.35E-07
6.02E-07
5.40E-05
7.80E-07
4.65E-06
3.84E-06
9.47E-07
6.02E-07
1.03E-06
5.44E-06
7.81 E-03
8.17E-03
1.32E-02
1.26E-05
7.53E-05
2.80E-04
2.63E-03
3.17E-04
4.00E-04
1.54E-06
5.20E-04
2.22E-05
Water Column
Exceedances
of Federal
Criteria
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Water Column
Exceedances
of AK State
Standards
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
A-10
-------
-------
APPENDIX 4-3
OFFSHORE CALIFORNIA
SURFACE WATER QUALITY ANALYSIS
A-ll
-------
-------
Water Column Pollutant Concentrations - CA
Baseline (Zero Discharge)
Pollutant Name
Prji9rHplis>IIutani©rgiapIiS£^^
Naphthalene
Fluorene
Phenanthrene
Phenol
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc_
Aluminum
Barium
Iron
Tin
Titanium
Alkylated benzenes
Alkylated naphthalenes
Alkylated fluorenes
Alkylated phenanthrenes
Alkylated phenols
Total biphenyls
Total dibenzothiophenes
Average Cone. Of
Pollutants in Model
SBF Well in Effluent
(mg/l)
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
Water Column
Cone. At 100
meters (mg/l)
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
Water Column
Exceedances of
Federal Criteria
0
0
0
0
0
0
0
0
0
0
0
0
0
0
A-12
-------
Water Column Pollutant Concentrations - CA
BAT Option 1
Pollutant Name
Priority Pollutarit'Organics
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metals*
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
_ead
vlickel
Selenium
Silver
Thallium
Zinc
VJon-ConventionairPoIlutarits,.
Aluminum
Barium
Iron
Tin
Titanium
Alkylated benzenes
Alkylated naphthalenes
Alkylated fluorenes
Alkylated phenanthrenes
Alkylated phenols
Total biphenyls
Total dibenzothiophenes
Average Cone. Of
Pollutants in Model
SBF Well in Effluent
(mg/l)
0.4987
0.2720
0.6451
0.0018
0.0730
0.0066
0.3783
0.4712
0.0465
15.9289
1.2411
2.3296
0.8960
0.0730
0.0465
0.0796
13.3072
601.9718
0.0730
1018.4055
0.9690
5.8074
2.8072
26.3908
3.1768
4.0137
0.0155
5.2168
0.2223
Water Column
Cone. At 100
meters (mg/l)
3.86E-05
2.11E-05
5.00E-05
1.36E-07
6.22E-07
9.25E-09
3.81 E-06
1.83E-07
4.68E-07
4.20E-05
6.06E-07
3.61 E-06
2.98E-06
7.35E-07
4.68E-07
8.02E-07
4.23E-06
6.06E-03
1.19E-08
1.03E-02
9.76E-06
5.85E-05
2.17E-04
2.04E-03
2.46E-04
3.11E-04
1.20E-06
4.04E-04
1.72E-05
Water Column
Exceedances of
Federal Criterici
0
0
0
0
0
0
0
0
0
0
0
0
0
0
A-13
-------
Water Column Pollutant Concentrations - CA
BAT Option 2
Pollutant Name
Naphthalene
Fluorene
Phenanthrene
Phenol
P;r|dntfIBoHut3Ht^!Metate^ &
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc ^ ^
Aluminum
Barium
Iron
Tin
Titanium
Alkylated benzenes
Alkylated naphthalenes
Alkylated fluorenes
Alkylated phenanthrenes
Alkylated phenols
Total biphenyls
Total dibenzothiophenes
Average Cone. Of
Pollutants in Model
SBF Well in Effluent
(mg/l)
0.4750
0.2591
0.6145
0.0017
0.0696
0.0063
0.3604
0.4489
0.0443
15.1752
1.1824
2.2194
0.8536
0.0696
0.0443
0.0759
12.6776
573.4885
37179.1542
970.2178
0.9232
5.5326
2.6738
25.1368
3.0259
3.8230
0.0147
4.9689
0.2117
Water Column
Cone. At 100
meters (mg/l)
3.68E-05
2.01 E-05
4.76E-05
1.29E-07
5.93E-07
8.82E-09
3.63E-06
1.74E-07
4.46E-07
4.00E-05
5.77E-07
3.44E-06
2.84E-06
7.00E-07
4.46E-07
7.64E-07
4.03E-06
5.78E-03
6.05E-03
9.77E-03
9.30E-06
5.57E-05
2.07E-04
1.95E-03
2.34E-04
2.96E-04
1.14E-06
, 3.85E-04
1.64E-05
Water Column
Exceedances of
Federal Criteria
0
0
0
0
0
0
0
0
0
0
0
0
0
0
A-14
-------
-------
APPENDIX 4-4
GULF OF MEXICO
SEDIMENT PORE WATER QUALITY ANALYSIS
A-15
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A-21
-------
APPENDIX 4-5
COOK INLET, ALASKA
SEDIMENT PORE WATER QUALITY ANALYSIS
A-22
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-------
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APPENDIX 4-6
*s>
OFFSHORE CALIFORNIA
SEDIMENT PORE WATER QUALITY ANALYSIS
A-26
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A-29
-------
-------
APPENDIX 4-7
GULF OF MEXICO
SEDIMENT GUIDELINES ANALYSIS
A-30
-------
-------
Sediment Guidelines Analysis - COM
Baseline
Metal
Pore Water
Cone. At 100 m
(ug/l)
FCV
(ug/0
Shallow Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
3.94E-01
3.84E-01
2.29E+00
1.89E+00
2.68E+00
9.3
3.1
8.1
8.2
81
Sum =
Shallow Water Exploratory Model Well
Cadmium
Copper
Lead
Nickel
Zinc
Sum =
8.26E-01
8.04E-01
4.79E+00
3.96E+00
5.61 E+00
9.3
3.1
8.1
8.2
81
Deep Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
5.96E-01
5.80E-01
3.46E+00
2.86E+00
4.05E+00
9.3
3.1
8.1
8.2
81
Sum =
Deep Water Exploratory Model Well
Cadmium
Copper
Lead
Nickel
Zinc
1.33E+00
1.29E+00
7.69E+00
6.36E+00
9.01 E+00
9.3
3.1
8.1
8.2
81
Sum =
Ratio of
Conc./FCV
4.24E-02
1.24E-01
2.82E-01
2.31 E-01
3.30E-02
7.12E-01
8.88E-02
2.59E-01
5.91 E-01
4.83E-01
6.92E-02
1.49E+00
6.41 E-02
1.87E-01
4.27E-01
3.49E-01
5.00E-02
1.08E+00
1.43E-01
4.16E-01
9.49E-01
7.76E-01
1.11 E-01
2.40E+00
A-31
-------
Sediment Guidelines Analysis - COM
BAT Option 1
Metal
Pore Water
Cone. At 100m
(ug/l)
FCV
(ug/i)
Shallow Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
1.33E-01
1.30E-01
7.73E-01
6.40E-01
9.06E-01
9.3
3.1
8.1
8.2
81
Sum =
Shallow Water Exploratory Model Well
Cadmium
Copper
Lead
Nickel
Zinc
Sum =
2.79E-01
2.72E-01
1.62E+00
1.34E+00
1.90E+00
9.3
3.1
8.1
8.2
81
Deep Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
2.02E-01
1.96E-01
1.17E+00
9.68E-01
1.37E+00
9.3
3.1
8.1
8.2
81
Sum =
Deep Water Exploratory Model Well
Cadmium
Copper
Lead
Nickel
Zinc
4.49E-01
4.37E-01
2.60E+00
2.15E+00
1.03E+00
9.3
3.1
8.1
8.2
81
Sum =
Ratio of
Conc./FCV
1.43E-02
4.19E-02
9.55E-02
7.80E-02
1.12E-02
2.41 E-01
3.00E-02
8.77E-02
2.00E-01
1.63E-01
2.34E-02
5.05E-01
2.17E-02
6.34E-02
1.44E-01
1.18E-01
1.69E-02
3.64E-01
4.82E-02
1.41 E-01
3.21 E-01
2.62E-01
1.27E-02
7.86E-01
A-32
-------
Sediment Guidelines Analysis - GOM
BAT Option 2
Metal
Pore Water
Cone. At 100 m
(ug/l)
FCV
(ug/l)
Shallow Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
1.23E-01
1.19E-01
7.11E-01
5.88E-01
8.33E-01
9.3
3.1
8.1
8.2
81
Sum =
Shallow Water Exploratory Model Well
Cadmium
Copper
Lead
Nickel
Zinc
Sum =
2.57E-01
2.50E-01
1.49E+00
1.23E+00
1.75E+00
9.3
3.1
8.1
8.2
81
Deep Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
5.77E-02
5.62E-02
3.35E-01
2.77E-01
6.64E-02
9.3
3.1
8.1
8.2
81
Sum =
Deep Water Exploratory Model Well
Cadmium
Copper
Lead
Nickel
Zinc
4.12E-01
4.02E-01
2.39E+00
1.98E+00
2.80E+00
9.3
3.1
8.1
8.2
81
Sum =
Ratio of
Conc./FCV
1.32E-02
3.85E-02
8.78E-02
7.17E-02
1.03E-02
2.21 E-01
2.76E-02
8.07E-02
1.84E-01
1.50E-01
2.15E-02
4.64E-01
6.21 E-03
1.81E-02
4.13E-02
3.38E-02
8.20E-04
1.00E-01
4.43E-02
1.30E-01
2.95E-01
2.41 E-01
3.46E-02
7.45E-01
A-33
-------
-------
APPENDIX 4-8
COOK INLET, ALASKA
SEDIMENT GUIDELINES ANALYSIS
A-34
-------
-------
Sediment Guidelines Analysis - AK
Baseline (Zero Discharge)
Metal
Pore Water
Cone. At 100 m
(ug/l)
FCV
(ug/l)
Shallow Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
9.3
3.1
8.1
8.2
81
Sum =
Ratio of
Conc./FCV
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
Sediment Guidelines Analysis - AK
BAT Option 1
Metal
Pore Water
Cone. At 100 m
(ug/l)
FCV
(ug/0
Shallow Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
1.79E-01
1.74E-01
1.04E+00
8.59E-01
1.22E+00
9.3
3.1
8.1
8.2
81
Sum =
Ratio of
Conc^FCV
1.93E-02
5.62E-02
1.28E-01
1.05E-01
1.50E-02
3.23E-01
Sediment Guidelines Analysis - AK
BAT Option 2
Metal
Pore Water
Cone. At 100 m
(ug/l)
FCV
(ug/0
Shallow Water Development Model Well
Cadmium
Copper
Lead
Nickel
Silver
Zinc
1.65E-01
1.60E-01
9.55E-01
7.90E-01
1.24E-01
1.12E+00
9.3
3.1
8.1
8.2
81
Sum =
Ratio of
Conc./FCV
1.77E-02
5.17E-02
1.18E-01
9.63E-02
1.38E-02
2.97E-01
A-35
-------
-------
APPENDIX 4-9
OFFSHORE CALIFORNIA
SEDIMENT GUIDELINES ANALYSIS
A-36
-------
-------
Sediment Guidelines Analysis - CA
Baseline (Zero Discharge)
Metal
Pore Water
Cone. At 100 m
(ug/I)
FCV
(ug/i)
Shallow Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
9.3
3.1
8.1
8.2
81
Sum =
Deep Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
9.3
3.1
8.1
8.2
81
Sum =
Ratio of
Conc./FCV
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
A-37
-------
Sediment Guidelines Analysis - CA
BAT Option 1
Metal
Pore Water
Cone. At 100 m
(ug/l)
FCV
(ug/l)
Shallow Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
1.79E-01
1.74E-01
1.04E+00
8.59E-01
1.22E+00
9.3
3.1
8.1
8.2
81
Sum =
Deep Water Development Model Well
Cadmium
Copper
Lead
Nickel
Zinc
2.71 E-01
2.64E-01
1.57E+00
1.30E+00
1.84E+00
9.3
3.1
8.1
8.2
81
Sum =
Ratio of
Conc./FCV
1.93E-02
• 5.62E-02
1.28E-01
1.05E-01
1.50E-02
3.23E-01
2.91 E-02
8.51 E-02
1.94E-01
1.59E-01
2.27E-02
4.90E-01
Sediment Guidelines Analysis - CA
BAT Option 2
Metal
Pore Water
Cone. At 100m
(ug/l)
FCV
(ug/i)
Shallow Water Development Model Well
Cadmium
Copper
Lead
Nickel
Silver
Zinc
1.65E-01
1.60E-01
9.55E-01
7.90E-01
1.24E-01
1.12E+00
9.3
3.1
8.1
8.2
81
Sum =
Deep Water Development Model Well
Cadmium
Copper
Lead
Nickel
Silver
Zinc
7.75E-02
7.55E-02
4.50E-01
3.72E-01
5.83E-02
1.69E+00
9.3
3.1
8.1
8.2
81
Sum =
Ratio of
Conc./FCV
1.77E-02
5.17E-02
1.18E-01
9.63E-02
1.38E-02
2.97E-01
8.33E-03
2.43E-02
5.55E-02
4.53E-02
2.09E-02
1.54E-01
A-38
-------
APPENDIX 5-1
OFFSHORE CALIFORNIA
HUMAN HEALTH RISK ANALYSIS
A-39
-------
-------
Recreational Finfish Tissue Pollutant Concentrations - CA
Baseline (Zero Discharge)
Pollutant Name
[ip'JSS^SSB&"ii iitarit^ Ot"rtani»»«f "
?-v^ £*>S£fiA*3^f i§S,v,T*5**M.* V/r y 9fi 1 %?5>^ ^
Naphthalene
Fluorene
Phenanthrene
Phenol
~
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional PlSJjutants
Aluminum
Barium
Iron
Tin
Titanium
Average Cone.
Of Pollutants
in Model SBF
Well Effluent
(mg/l)
,- ,^!S, "'
^
0.0000
0.0000
0.0000
0.0000
•"*"•* J,
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
'. "••"*?
0.0000
0.0000
0.0000
0.0000
0.0000
Ambient
Bioavailable
Cone, in
Plume
(mg/l)
& V",
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
- 'v^*= - $#>'•?
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
— . ' i *** '•
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
Average
Exposure
Cone.
(mg/l)
- »-
•Sv\
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
^%a.^_
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
/' ,r • '
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
Fish Tissue
Concentration
(mg/kg)
^ *2,
~\ ^ ^^^^^h-^^^.'9.
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
/ ' " -
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
" '_£, ", ,~ .
O.OOE+00
A-40
-------
Recreational Finfish Health Risks - CA
Baseline (Zero Discharge)
Pollutant Name
Priority Pollutant Orgariics
Naphthalene
Fluorene
Phenanthrene
Phenol
Prfority PoUulaHtsTMSIC"
Cadmium
Mercury
Antimony
Arsenic
Beryiium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
Iron
Tin
Titanium
Fish Tissue
Concentration
(mg/kg)
."" "' "
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
99th
Percentile
Intake
(mg/kg-day)
O.dOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
•
O.OOE+00
99th
Percentile
Hazard
Quotient
(mg/kg-day)
J /
O.OOE+00
O.OOE+00
O.OOE+00
# ^ * a
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
" *~
O.OOE+00
Lifetime
Excess
Cancer Risk
(30 yr
Exposure)
' ?*^ ~*
r s' "'
s t~T »3<
O.OOE+00
^ -*
Lifetime
Excess
Cancer Risk
(70 yr
Exposure)
f f t
, f> * "
O.OOE+00
'-„ , , --*
A-41
-------
Recreational Finfish Tissue Pollutant Concentrations - CA
BAT Option 1
Pollutant Name
p^^^^;-l|^|^iir|t,'O^an.icSt'y ,
Naphthalene
Fluorene
Phenanthrene
Phenol
Pjlorflf : 'po§Sarits#Meta!s * ii~;
Cadmium
Mercury
Antimony
Arsenic .
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conyentional PoHutanfs
Aluminum
Barium
Iron
Tin
Titanium
Average
Cone. Of
Pollutants in
Model SBF
Well Effluent
(mg/l)
y-s^ -f -&
0.4987
0.2720
0.6451
0.0018
. VM "*'&&
0.0730
0.0066
0.3783
0.4712
0.0465
15.9289
1.2411
2.3296
0.8960
0.0730
0.0465
0.0796
13.3072
'—• "
601.9718
0.0730
1018.4055
0.9690
5.8074
Ambient
Bioavailable
Cone. In
Plume
(mg/l)
* " * ^~
7.30E-05
3.98E-05
9.44E-05
2.57E-07
Vwjj4>\ 'jB**®^1
1.18E-06
1.75E-08
7.20E-06
3.45E-07
8.84E-07
7.93E-05
1.14E-06
6.82E-06
5.64E-06
1.39E-06
8.84E-07
1.52E-06
7.99E-06
' -^ *• ~l"f ^
8.81 E-02
1.07E-05
1.49E-01
1.42E-04
8.50E-04
Average
Exposure
Cone.
(mg/l)
? f ^
3.06E-07
1.67E-07
3.95E-07
1.08E-09
^JSfSSrSSife
4.92E-09
7.32E-11
3.02E-08
1.44E-09
3.70E-09
3.32E-07
4.79E-09
2.86E-08
2.36E-08
5.82E-09
3.70E-09
6.35E-09
3.34E-08
t"
3.69E-04
4.48E-08
6.24E-04
5.94E-07
3.56E-06
Fish Tissue
Concentration
(mg/kg)
". >»" "*fiv ^
1.30E-04
5.00E-06
1.04E-03
1,51 Er09
-V,vi*i.- ' '...^'. :/A^*i\
3.15E-07
4.03E-07
3.02E-08
6.36E-08
7.04E-08
5.31 E-06
1.73E-07
1.40E-06
1.11E-06
2.79E-08
1.85E-09
7.36E-07
1.57E-06
,, >f,t "*r ;~
8.52E-02
A-42
-------
Recreational Finfish Health Risks - CA
BAT Option 1
Pollutant Name
Prinrifv Pollutant Oroahip*?
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metals" ",„"
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
iron
Tin
Titanium
Fish Tissue
Concentration
(mg/kg)
1.30E-04
5.00E-06
1.04E-03
1.51E-09
3.15E-07
4.03E-07
3.02E-08
6.36E-08
7.04E-08
5.31 E-06
1.73E-07
1.40E-06
1.11 E-06
2.79E-08
1.85E-09
7.36E-07
1.57E-06
8.52E-02
99th
Percentile
Intake
(mg/kg-day)
^.
2.59E-07
9.96E-09
2.07E-06
3.00E-12
'^m:'-i
6.27E-10
8.02E-10
6.00E-11
1.26E-10
1.40E-10
1.06E-08
3.43E-10
2.79E-09
2.21 E-09
5.56E-11
3.68E-12
1.47E-09
3.13E-09
1.70E-04
99th
Percentile
Hazard
Quotient
(mg/kg-day)
1.30E-05
2.49E-07
5.00E-12
6.27E-07
2.67E-06
1.50E-07
4.22E-07
3.52E-06
1.10E-07
1.11E-08
7.37E-10
1.83E-05
1.04E-08
O.OOE+00
Lifetime
Excess
Cancer Risk
(30 yr
Exposure)
,/• ' , ' r
i^iifeSilKli
3.61 E-11
~- ,
Lifetime
Excess
Cancer Risk
(70 yr
Exposure)
* "f
# i f *
8.43E-11
•< y~,- . -
A-43
-------
Recreational Finfish Tissue Pollutant Concentrations - CA
BAT Option 2
Pollutant Name
Priol^l^iiK^Ji^fflcIf"^ *
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority PoIlutants,JVfeT:als - ' bl
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants ;*-
Aluminum
Barium
Iron
Tin
Titanium
Average Cone.
Of Pollutants in
Model SBF Well
Effluent
(mg/l)
*«*' " > ;"
0.4750
0.2591
0.6145
0.0017
s., s'~*.'
0.0696
0.0063
0.3604
0.4489
0.0443
15.1752
1.1824
2.2194
0.8536
0.0696
0^0443
0.0759
12.6776
J-\1^'lf"
573.4885
37179.1542
970.2178
0.9232
5.5326
Ambient
Bioavailable
Cone. In Plume
(mg/l)
" ' '^ysff ^-
6.95E-05
3.79E-05
9.00E-05
2.45E-07
- -,,*'/• ^'~ •<
1.12E-06
1.67E-08
6.86E-06
3.29E-07
8.42E-07
7.55E-05
1.09E-06
6.50E-06
5.37E-06
1.32E-06
8.42E-07
1.44E-06
7.61 E-06
j," JUUS-^ ' '~*'"~ '
8.40E-02
5.44E+00
1.42E-01
1.35E-04
8.10E-04
Average
Exposure
Cone.
(mg/l)
"•
2.91 E-07
1.59E-07
3.77E-07
1.02E-09
- . ^ -.",. ^ - i
4.69E-09
6.98E-11
2.87E-08
1.38E-09
3.53E-09
3.16E-07
4.57E-09
2.72E-08
2.25E-08
5.54E-09
3.53E-09
6.05E-09
3.19E-08
"/^s •' >~. * -
3.52E-04
2.28E-02
5.95E-04
5.66E-07
3.39E-06
Fish Tissue
Concentration
(mg/kg)
-"-'.... ~Z hfe^5 1.-~ -' '.
1.24E-04
4.76E-06
9.91 E-04
1.43E-09
j ^ ^ ",
3.00E-07
3.84E-07
2.87E-08
6.05E-08
6.70E-08
5.06E-06
1.64E-07
1.33E-06
1.06E-06
2.66E-08
1.76E-09
7.01 E-07
J.5DE?06
- —
-------
Recreational Finfish Health Risks - CA
BAT Option 2
Pollutant Name
Fish Tissue
Concentration
(mg/kg)
Priority Pollutant Orjganics. , ^_
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, MetaJ4i~
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum (
Barium
Iron
Tin
Titanium
1.24E-04
4.76E-06
9.91 E-04
1.43E-09
3.00E-07
3.84E-07
2.87E-08
6.05E-08
6.70E-08
5.06E-06
1.64E-07
1.33E-06
1.06E-06
2.66E-08
1.76E-09
7.01 E-07
1.50E-06
:.;>-s'V. .,.
8.12E-02
99th
Percentile
Intake
(mg/kg-day)
V -V4
2.47E-07
9.48E-09
1.97E-06
2.86E-12
"
5.97E-10
7.64E-10
5.72E-11
1.20E-10
1.33E-10
1.01E-08
3.27E-10
2.65E-09
2.10E-09
5.29E-1 1
3.51 E-1 2
1.40E-09
2.98E-09
J
1.62E-04
99th
Percentile
Hazard
Quotient
(mg/kg-day)
, -
1.23E-05
2.37E-07
4.76E-12
* ,s
5.97E-07
2.55E-06
1.43E-07
4.02E-07
3.36E-06
1.05E-07
1.06E-08
7.02E-10
1.74E-05
9.93E-09
'*#• "*$
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
•*
^ '** ''•'"
A-45
_
-------
Commercial Shrimp Tissue Pollutant Concentrations - CA
Shallow Water Development Model Well
Baseline (Zero Discharge)
Pollutant Name
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority PoJlutantCMetafe^
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Poliutlrits
Aluminum
Barium
Iron
Tin
Titanium
Annual
Pollutant
Loadings (mg)
per SWD Model
SBFWeU
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
f X^
f.irf-'WR-* -^v™ y
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
, < -V*" M py^ ,
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00 -
O.OOE+00
Pollutant
Sediment
Concentration
,(mg poll/kg sed)
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
•"/>/*» „ ,
•C" f
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
-V
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
Estimated
Pore Water
Cone, (mg/l)
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
';X—
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
0,0,QE+00
"' " ^^.~
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
Shrimp
Tissue
Cone.
(mg/,kg)
o:ooE+oo
O.OOE+00
O.OOE+00
,0,OOE+00
. - >
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
xmoE-too
• —
O.OOE+00
A-46
-------
Commercial Shrimp Health Risks - CA
Shallow Water Development Model Well
Baseline (Zero Discharge) ~:
Pollutant Name
Priority Poilufani Prganlc^K
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutantsj MllITs"
Cadmium
Mercury
Antimony
Arsenic
Beryiium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Cohveritfonal[PjoliulaiiiC
Aluminum
Barium
Iron
Tin
Titanium
Shrimp
Tissue
Cone.
(mg/kg)
;•-' •
O.OOE+00
O.OOE+00
o.ooE+db
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+OO"
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00-
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
99th
Percentile
Intake
(mg/kg-day)
-', If^f'- ' '.§'. Ji^J '. ' •
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
-
O.OOE+00
O.OOE+dO
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
- ., v-
O.OOE+00
99th
Percentile
Hazard
Quotient
(mg/kg-day)
If^'Stlllr?
O.OOE+00
O.OOE+00
O.OOE+00
s
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
, O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
_-.,
O.OOE+00
Lifetime
Excess
Cancer Risk
(30 yr
Exposure)
A
O.OOE+00
„ ,*•}?"' S^
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
^ ' ^,
O.OOE+00
T^f'",5v
A-47
-------
Commercial Shrimp Tissue Pollutant Concentrations - CA
Shallow Water Development Model Well
BAT Option 1
Pollutant Name
t'^^'.'-tiigi^^y^^^i^^&f^'&z^&^^ffi A* al( ji*^< -• ^
if 'r;pjri^l|Q|Manf Qrganics-i : ~
Naphthalene
Fluorene
Phenanthrene
Phenol
• ~ "
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Noli[-Coriye,ntipriar:P,fttlutarits "
Aluminum
Barium
Iron
Tin
Titanium
Annual
Pollutant
Loadings (mg)
per SWD Model
SBF Well
i. 5 *
5.42E+04
2.96E+04
7.02E+04
1.91E+02
' - ","'/
7.94E+03
7.22E+02
4.11 E+04
5.12E+04
5.05E+03
1.73E+06
1.35E+05
2.53E+05
9.74E+04
7.94E+03
5.05E+03
8.66E+03
1.45E+06
„! "-" i"-
6.55E+07
4.24E+09
1.11E+08
1.05E+05
6.32E+05
Pollutant
Sediment
Concentration
(mg poll/kg sed)
-,- :, : ~" .
8.16E-04
4.45E-04
1.06E-03
2.87E-06
" \ .r^-w-x
1.19E-04
1.09E-05
6.19E-04
7.71 E-04
7.60E-05
2.61 E-02
2.03E-03
3.81 E-03
1.47E-03
1.19E-04
7.60E-05
1.30E-04
2.18E-02
>, i/ - *™ */•
9.85E-01
6.39E+01
1.67E+00
1.59E-03
9.50E-03
Estimated
Pore Water
Cone.
(ros/kg)
-,-
7.10E-05
1.98E-05
1.30E-05
3.56E-05
** A.-
1.44E-05
2.14E-07
8.79E-05
4.21 E-06
1.08E-05
9.68E-04
1.40E-05
8.33E-05
6.89E-05
1.70E-05
1.08E-05
1.85E-05
9.75E-05
„ '* ''•,
1.40E-01
1.46E-01
2.37E-01
2.25E-04
1.35E-03
Shrimp
Tissue
Cone.
(mg/kg)
*• s- > &s
-------
Commercial Shrimp Health Risks - CA
Shallow Water Development Model Well
BAT Option 1
Pollutant Name
Priority PoIlutantOrganlcs^ "
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metajs
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
'Jon-Conventional Pollutants,
Aluminum
Barium
Iron
Tin
Titanium
Shrimp
Tissue
Cone.
(mg/kg)
3.33E-04
6.53E-06
3.77E-04
5.48E-07
1.01E-05
1.29E-05
9.67E-07
2.04E-06
2.26E-06
1.70E-04
5.53E-06
4.49E-05
3.56E-05
8.96E-07
5.94E-08
2.36E-05
5.04E-05.
3.55E-01
99th
Percentile
Intake
(mg/kg-day)
'
1.52E-12
2.98E-14
1.72E-12
2.50E-15
I.""
4.61 E-1 4
5.89E-14
4.41 E-1 5
9.29E-15
1.03E-14
7.76E-13
2.52E-14
2.05E-13
1.62E-13
4.08E-15
2.71 E-1 6
1.08E-13
2.30E-13
1.62E-09
99th
Percentile
Hazard
Quotient
(mg/kg-day)
'^
7.58E-11
7.44E-13
4.16E-15
X
4.61 E-1 1
1.96E-10
1.10E-11
3.10E-11
2.59E-10
8. 11 E-1 2
8.16E-13
5.41 E-14
1.35E-09
7.66E-13
s-
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
to / ?/r
2.65E-15
^ # i~ "^f , * -
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
',
6.19E-15
„ .; s
A-49
-------
Commercial Shrimp Tissue Pollutant Concentrations - CA
Shallow Water Development Model Well
BAT Option 2
Pollutant Name
Naphthalene
Fluorene
Phenanthrene
Phenol
$j^~-^£>f'£^'f&jjSBK??-$-mfi$"V$tf*S*l$® . -< . .
iirroyiyStfatantiSitMetals ,
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
N61h«C,bnventiojrialJE!,ollutants_ „ „ ^
Aluminum
Barium
Iron
Tin
Titanium
Annual Pollutant
Loadings (mg)
per SWD Model
SBF We'll
"?» *N „,-. „ , ,
4.99E+04
2.72E+04
6.45E+04
1.76E+02
<"~ , ^ ^^" "*
7.30E+03
6.64E+02
3.78E+04
4.71 E+04
4.65E+03
1.59E+06
1.24E+05
2.33E+05
8.96E+04
7.30E+03
4.65E+03
7.96E+03
1.33E+06
< / * ~-~*
6.02E+07
3.90E+09
1.02E+08
9.69E+04
5.81 E+05
Pollutant
Sediment
Concentration
(mg poll/kg sed)
*•+»#.***. "* "*
7.50E-04
4.09E-04
9.71 E-04
2.64E-06
-*^K T^ * >•
1.10E-04
9.98E-06
5.69E-04
7.09E-04
6.99E-05
2.40E-02
1.87E-03
3.50E-03
1.35E-03
1.10E-04
6.99E-05
1.20E-04
2.00E-02
*•*<** -^ -*.
9.06E-01
5.87E+01
1.53E+00
1.46E-03
8.74E-03
Estimated
Pore Water
Cone.
(mg/kg)
-
6.52E-05
1.82E-05
1.20E-05
3.27E-05
'«?-<>-
1.32E-05
1.96E-07
8.08E-05
3.87E-06
9.92E-06
8.90E-04
1.28E-05
7.66E-05
6.33E-05
1.56E-05
9.92E-06
1.70E-05
8.97E-05
"• r ^ SN
1.29E-01
1.35E-01
2.18E-01
2.07E-04
1.24E-03
Shrimp
Tissue
Cone.
(ma/kg)
3.06E-04
6.01 E-06
3.47E-04
5.04E-.07
-C ~- ;=/
9.29E-06
1.19E-05
8.89E-07
1.87E-06
2.07E-06
1.57E-04
5.09E-06
4.13E-05
3.27E-05
8.23E-07
5.46E-08
2.17E-05
4.64E-05
•
3.27E-01
A-50
-------
Commercial Shrimp Health Risks - CA
Shallow Water Development Model Well
BAT Option 2
Pollutant Name
Prlorit^PoilMtantjPrganicS; .^ J
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metals
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Ndn-Conyenfiojial, Pollutants
Aluminum
Barium
Iron
Tin
Titanium
Shrimp
Tissue
Cone.
(mg/kg)
3.06E-04
6.01 E-06
3.47E-04
5.04E-07
9.29E-06
1.19E-05
8.89E-07
1.87E-06
2.07E-06
1.57E-04
5.09E-06
4.13E-05
3.27E-05
8.23E-07
5.46E-08
2.17E-05
4.64E-05
3.27E-01
99th
Percentile
Intake
(mg/kg-day)
1.39E-12
2.74E-14
1.58E-12
2.30E-15
>
4.23E-14
5.41 E-14
4.05E-15
8.54E-15
9.45E-15
7.14E-13
2.32E-14
1.88E-13
1.49E-13
3.75E-15
2.49E-16
9.89E-14
2.11 E-1 3
*, ">f,i~ - ^ '
1.49E-09
99th
Percentile
Hazard
Quotient
(mg/kg-day)
6.97E-11
6.84E-13
3.83E-15
-
4.23E-11
1.80E-10
1.01 E-1 1
2.85E-11
2.38E-10
7.46E-12
7.51 E-1 3
4.98E-14
1.24E-09
7.04E-13
,
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
^s s
2.44E-15
_
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
^ * „
5.69E-15
\
A-51
-------
APPENDIX 5-2
GULF OF MEXICO
RECREATIONAL FISHERIES
HUMAN HEALTH RISK ANALYSIS
A-52
-------
-------
Recreational Finfish Tissue Pollutant Concentrations - GOM
Baseline
Pollutant Name
?£J"iS$?r. ;5^ys« rS:£^y^^^-i^SS^^^^^S^ "" S^> ' > "M
i®rityjlS>11il^Mfgariros,'r-; , ,
Naphthalene
Fluorene
Phenanthrene
Phenol
PCjo.rj^^R^ij)trt9__ntS')ii»i,etai§,£;^^,,
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
iSiPiS^^^iiSi^ni^^
Aluminum
Barium
Iron
Tin
Titanium
Average Cone.
Of Pollutants
in Model SBF
Well Effluent
(mg/l)
»-""-'• . l-i, _ „. ~
1.0995
0.5997
1.4225
0.0039 .
- ^$i$$% .'$*9$*$K^' Ti^
0.1610
0.0146
0.8342
1.0391
0.1024
35.1248
2.7368
5.1370
1.9758
0.1610
0.1024
0.1756
29.3439
•/s^T^ ' -s&i/s' *' >'-<•$&' ,v
K^S • ';?/?%% ,/ ,&*jj%&t
1327.4109
86055.8132
2245.6908
2.1368
12.8059
Ambient
Bioavailable
Cone. In
Plume
(mg/I)
__"'? Zx,..f
6.16E-05
3.36E-05
7.96E-05
2.17E-07
.^ y&S&&^ '%&+?&
9.92E-07
. 1.48E-08
6.07E-06
2.91 E-07
7.46E-07
- 6.69E-05
9.65E-07
5.75E-06
4.76E-06
1.17E-06
•~~- 7.46E-07
1.28E-06
6.74E-06
i. ;3*?^? '^3
7.43E-02
4.82E+00
1.26E-01
1.20E-04
7.17E-04
Average
Exposure
Cone.
(mg/l)
" ~ ""f°"
6.80E-07
3.71 E-07
8.80E-07
2.39E-09
?*S3^*'J, ' - 'z» ' .'
1.10E-08
1.63E-10
6.71 E-08
3.21 E-09
8.24E-09
7.39E-07
1.07E-08
6.36E-08
5.26E-08
1.29E-08
8.24E-09
1.41 E-08
7.44E-08
i^ftsT- „ •" -,
8.21 E-04
5.32E-02
1.39E-03
1.32E-06
7.92E-06
Fish Tissue
Concentration
(mg/kg)
!**'~ •' -*^-*.v.\.
2.90E-04
1.11E-05
2.31 E-03
.. 3..35E709
^^V^;;^^' '£/• j£ -
7.01 E-07
8.96E-07
6.71 E-08
1.41 E-07
1.57E-07
1.18E-05
3.84E-07
3.11E-06
2.47E-06
6.21 E-08
4.12E-09
1.64E-06
3.50E-06
-rT* *rJ- ' •''?!
1.90E-01
A-53
-------
Recreational Finfish Health Risks - COM
Baseline
Pollutant Name
Priority PoHutantlOrganics™
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metaj'Cl.
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
Iron
Tin
Titanium
Fish Tissue
Concentration
(mg/kg)
2.90E-04
1.11E-05
2.31 E-03
3.35E-09
7.01 E-07
8.96E-07
6.71 E-08
1.41 E-07
1.57E-07
1.18E-05
3.84E-07
3.11E-06
2.47E-06
6.21 E-08
4.12E-09
1.64E-06
3.50E-06
,, •/ • ••-••
1.90E-01
99th
Percentile
Intake
(mg/kg-day)
s
5.77E-07
2.21 E-08
4.61 E-06
6.67E-12
*
1.40E-09
1.78E-09
1.34E-10
2.81 E-10
3.12E-10
2.35E-08
7.64E-10
6.20E-09
4.92E-09
1.24E-10
8.20E-12
3.26E-09
6.96E-09
• M'-'SSi,
3.77E-04
99th
Percentile
Hazard
Quotient
(mg/kg-day)
c ' *"\
2.88E-05
5.54E-07
1.11E-11
',
1.40E-06
5.95E-06
3.34E-07
9.38E-07
7.84E-06
2.46E-07
2.47E-08
1.64E-09
4.08E-05
2.32E-08
S'iSi- .-.SK* -: - „•--
*»:" -, . ;W5&,. .• • •..-
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
'^ " ^ \ ^
/ /
8.04E-1 1
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
• '
,s ,-,
1.88E-10
•
A-54
-------
Recreational Finfish Tissue Pollutant Concentrations <
BAT Option 1
GOM
Pollutant Name
;^^|fiililutiirl!QrggnJcs ^
Naphthalene
Fluorene
Phenanthrene
Phenol
•PiBriiltf'P'SlMtaS^^iiiKtiJ^i • '
^fwMi^Tjfeir^v-AMS^i'iArets™*^"*^!^*' *"" ^
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants^
Aluminum
Barium
ron
Tin
Titanium
Average Cone.
Of Pollutants in
Model SBF Well
_ Effluent
"* (mg/l)
~"y--
0.4987
0.2720
0.6451
0.0018
™x^*^^^4?rv-':"-^!°^^&
**.&£&• ^..r.'.V-vfc .'•'.''•'^^m
0.0730
0.0066
0.3783
0.4712
0^0465
15.9289
1.2411
2,3296
0.8960
0.0730
0.0465
0.0796
13,3072
•<-»»., ^ ~*~ --
601.9718
0.0730
1018.4055
0.9690
5.8074
Ambient
Bioavailable
Cone. In
Plume
(mg/l)
f * "*•
2.79E-05
1.52E-05
3.61 E-05
9.83E-08
$gj^V;V^-':'1j|f?V a "
^^^»'-*
3.08E-07
1.68E-07
3.99E-07
1.09E-09
, ' -^,-9* ^ t
* «- ^
4.97E-09
7.39E-11
3.04E-08
1:46E-09
3.74E-09
3.35E-07
4.84E-09
2.88E-08
2.38E-08
5.87E-09
3.74E-09
6.41 E-09
3.38E-08
3.72E-04
4.52E-08
6.30E-04
5.99E-07
3.59E-06
Fish Tissue
Concentration
(mg/kg)
•>«• _1_ "i^
1.31E-04
"."••' 5.05E-06
1.05E-03
1.52E-09
*r 2 '<^' ' "'
*v » _ j *^i
3.18E-07
" 4.06E-07
3.04E-08
~ 6A1E-Q8
V; 7.10E-08
5.36E-06
••-"". 1.74E-07
1.41E-06
1.12E-06
r 2.82E-08
; 1.87E-09
7.43E-07
1.59E-06
/"""• '^, , xi* —
8.60E-02
.:'•:'•-•"•.
A-55
-------
Recreational Finfish Health Risks - GOM
BAT Option 1
Pollutant Name
|L_,*V» ~> iri *™ _. 'i"'i»»»j_' i' * j ; » i <•' jpj]]jiiiiiiii,».*ii*j «^*»Hi. i J¥UilE
Priority Pollutant Orgamcs
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metals *
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
iron
Tin
Titanium
Fish Tissue
Concentration
(mg/kg)
"
1.31E-04
5.05E-06
1.05E-03
1.52E-09
3.18E-07
4.06E-07
3.04E-08
6.41 E-08
7.10E-08
5.36E-06
1.74E-07
1.41E-06 '
1.12E-06
2.82E-08
1.87E-09
7.43E-07
1.59E-06
~ ~
8.60E-02
99th
Percentile
Intake
(mg/kg-day)
- ., -'
2.62E-07
1.00E-08
2.09E-06
3.02E-12
. -' . . ... -«
6.33E-10
8.09E-10
.- 6.05E-11
1.28E-10
1.41E-10
1.07E-08
3.47E-10
2.81 E-09
2.23E-09
5.61 E-11
3.72E-12
1.48E-09
3.16E-09
-
1.71E-04
99th
Percentile
Hazard
Quotient
(mg/kg-day)
-^ ff ? */ /?
1.31E-05
2.51 E-07
5.04E-12
-L^-f&^t'1'*
6.33E-07
2.70E-06
1.51 E-07
4.25E-07
3.56E-06
1.11 E-07
1.12E-08
7.44E-10
1.85E-05
1.05E-08
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
^
3.65E-11
•£*
/ ^
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
• s - j
v ,"'„'*
8.51 E-11
•V ' " * -
A-56
-------
Recreational Finfish Tissue Pollutant Concentrations - COM
BAT Option 2
Pollutant Name
Priority- Pol lutant p/jganfos ' «• -t
Naphthalene
Fluorene
Phenanthrene
Phenol
g^i^rtl)®msiiais^">" '-
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
lonWoilipt! na^PpSnW" <
Aluminum
Barium
Iron
Tin
Titanium
Average Cone.
Of Pollutants in
Model SBF Well
Effluent
(mg/l)
i~" ''-ST -• "' 5
0.4750
0.2591
0.6145
0.0017
"T" , - :;-
0.0696
0.0063
0.3604
0.4489
0.0443
15.1752
1.1824
2.2194
0.8536
0.0696
0.0443
0.0759
12.6776
^ *;*•• -,-.-^ •*
573.4885
37179.1542
970.2178
0.9232
5.5326
Ambient
Bioavailable
Cone. In
Plume
(mg/l)
" _ _ "^ "•
2.66E-05
1.45E-05
3.44E-05
9.36E-08
^ ""
4.28E-07
6.37E-09
2.62E-06
1.26E-07
3.22E-07
2.89E-05
4.17E-07
2.49E-06
2.06E-06
5.06E-07
3.22E-07
5.52E-07
2.91E-06
~z <~ * •"-
3.21E-02
2.08E+00
5.43E-02
5.17E-05
3.10E-04
Average
Exposure
Cone.
(mg/l)
Vv. ~" 1 "
2.94E-07
1.60E-07
3.80E-07
1.03E-09
^ ~ *"*,L ". ~
4.73E-09
7.04E-11
2.90E-08
1.39E-09
3.56E-09
3.19E-07
4.61 E-09
2.75E-08
2.27E-08
5.59E-09
3.56E-09
6.10E-09
3-22E-08
" - , - ->
3.55E-04
2.30E-02
6.00E-04
5.71 E-07
3.42E-06
:-
Fish Tissue
Concentration
(mg/kg) ,
** « ,'»<"
i:25E-04
4.81 E-06
1.00E-03
1.45E-09
'-."^ ':j-~ • -, r~'^ J
3.03E-07
. 3.87E-07
2.90E-08
6.11E-08
6.76E-08
5. 11 E-06
1.66E-07
1.35E-06
1.07E-06
2.68E-08
1.78E-09
7.08E-07
..15.1&06
« ~ ~"
8.20E-02
A-57
-------
Recreational Finfish Health Risks - COM
BAT Option 2
Pollutant Name
Priority Pollutantbrganics^
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metals,,,
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
Iron
Tin
Titanium
--".
Fish Tissue
Concentration
(mg/kg)
1.25E-04
4.81 E-06
1.00E-03
1.45E-09
3.03E-07
3.87E-07
2.90E-08
6.11E-08
6.76E-08
5.11 E-06
1.66E-07
1.35E-06
1.07E-06
2.68E-08
1.78E-09
7.08E-07
1.51 E-06
-— ~1"
8.20E-Q2
-••' L L
99th
Percentile
Intake
(mg/kg-day)
2.49E-07
9.57E-09
1.99E-06
2.88E-12
\:
6.03E-10
7.71 E-10
5.77E-11
1.22E-10
1.35E-10
1.02E-08
3.30E-10
2.68E-09
2.12E-09
5.34E-11
3.54E-12
1.41E-09
3.01 E-09
? ^
1.63E-04
99th
Percentile
Hazard
Quotient
(mg/kg-day)
1.25E-05
2.39E-07
4.80E-12
— '^
6.03E-07
2.57E-06
1.44E-07
4.05E-07
3.39E-06
1.06E-07
1.07E-08
7.08E-10
1.76E-05
1.00E-08
-5
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
' }
-' '
—
3.47E-11
< , ' ••"'
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
8.11E-11
sf-
A-58
-------
APPENDIX 5-3
COOK INLET, ALASKA
RECREATIONAL FISHERIES
HUMAN HEALTH RISK ANALYSIS
A-59
-------
-------
Recreational Finfish Health Risks - AK
Baseline (Zero Discharge)
Pollutant Name
Naphthalene
Fiuorene
Phenanthrene
Phenol
friof|ty;llKial.?@1fISlS' -
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Bla^^inisiSiyiHiarsfcs
Aluminum
Barium
ron
Tin
Titanium
Fish Tissue
Concentration
(mg/kg)
^ j *
i -* , ,
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
-»-','
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
,^ -- .
O.OOE+00
'
99th
Percentile
Intake
(mg/kg-day)
V ~-
-------
Recreational Finfish Tissue Pollutant Concentrations - AK
Baseline (Zero Discharge)
Pollutant Name
Priority Pollutant -.Organics^,..!
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metals
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventlorii^lT'ollularifst
Aluminum
Barium
Iron
Tin
Titanium
Average Cone.
Of Pollutants
in Model SBF
Well Effluent
(mg/l)
•:.',** .-«
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
Ambient
Bioavailable
Cone. In
Plume
(mg/l)
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
/
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
>• if tt
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
Average
Exposure
Cone.
(mg/l)
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
, '
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
/""';.
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
Fish Tissue
Concentration
(mg/kg)
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
^ / -f-
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
. O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
-, •-
O.OOE+00
A-61
-------
Recreational Finfish Tissue Pollutant Concentrations - AK
BAT Option 1
Pollutant Name
1 liie^gllltant drganias--*
Naphthalene
Fluorene
Phenanthrene
Phenol
ig^i^^lteni!sH«efalst .
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Aluminum
Barium
ran
Tin
Titanium
Average Cone.
Of Pollutants
in Model SBF
Well Effluent
(mg/l)
*->*
0.4987
0.2720
0.6451
.0,0018
_- — j.
0.0730
0.0066
0.3783
0.4712
0.0465
15.9289
1.2411
2.3296
0.8960
0.0730
0.0465
0.0796
13.3072
* / ?• •"•?-,
601.9718
0.0730
1018.4055
0.9690
5.8074
Ambient
Bioavailabie
Cone. In
Plume
(mg/l)
" " *-"..„
9.39E-05
5.12E-05
1.21E-04
3.30E-07
N T*~ <%-,_.,
1.51E-06
2.25E-08
9.26E-06
4.44E-07
1.14E-06
1.02E-04
1.47E-06
8.77E-06
7.25E-06
1.79E-06
1.14E-06
1.95E-06
1.03E-05
'.£ U.!.tflB
1.13E-01
1.37E-05
1.92E-01
1.82E-04
1.09E-03
Average
Exposure
Cone.
(mg/l)
f; -? --"
3.11E-07
1.70E-07
4.03E-07
1.10E-09
, f- — i.
5.01 E-09
7.46E-11
3.07E-08
1.47E-09
3.77E-09
3.38E-07
4.88E-09
2.91 E-08
2.40E-08
5.92E-09
3.77E-09
6.46E-09
3.41 E-08
3.76E-04
4.56E-08
6.36E-04
6.05E-07
3.63E-06
Fish Tissue
Concentration
(mg/kg)
-A.- -
1.33E-04
5.09E-06
1.06E-03
1.53E-09
-aii,/ C~^
3.21 E-07
4.10E-07
3.07E-08
6.47E-08
7.16E-08
5.41 E-06
1.76E-07
1.43E-06
1.13E-06
2.84E-08
1.89E-09
7.50E-07
1.60E-06
8.68E-02
A-62
-------
Recreational Finfish Health Risks - AK
BAT Option 1
Pollutant Name
Priority Pollutant Orgarjics**"""
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metals
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
Iron
Tin
Titanium
Fish Tissue
Concentration
(mg/kg)
1.33E-04
5.09E-06
1.06E-03
1.53E-09
3.21 E-07
4.10E-07
3.07E-08
6.47E-08
7.16E-08
5.41 E-06
1.76E-07
1.43E-06
1.13E-06
2.84E-08
1.89E-09
7.50E-07
1.60E-06
8.68E-02
99th
Percentile
Intake
(mg/kg-day)
r4 ' ' ' *" f
3.60E-07
1.38E-08
2.87E-06
4.16E-12
8.70E-10
1.11E-09
8.33E-11
1.76E-10
1.94E-10
1.47E-08
4.77E-10
3.87E-09
3.07E-09
7.71 E-11
5.11E-12
2.03E-09
4.34E-09
-' ; -',',-
2.35E-04
99th
Percentile
Hazard
Quotient
(mg/kg-day)
_ .
' •;»-
1.80E-05
3.45E-07
6.93E-12
-
8.70E-07
3.71 E-06
2.08E-07
5.85E-07
4.89E-06
1.53E-07
1.54E-08
1.02E-09
2.54E-05
1.45E-08
"
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
J /
•V
5.02E-11
Lifetime
Excess
Cancer
Risk
(70 yr
[Exposure)
)
1.17E-10
*/• /'
A-63
-------
Recreational Finfish Tissue Pollutant Concentrations - AK
BAT Option 2
Pollutant Name
©rgaiicsi •- .''
Naphthalene
Fluorene
Phenanthrene
Phenol
Cadmium •
Mercury
Antimony. *
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
ll.^^onVejtitidiEial^pHutanlP'' „•
Aluminum
Jarium
ran
In
Titanium
Average Cone.
Of Pollutants
in Model SBF
Well Effluent
(mg/l)
""*„*• — ?''""**'•"&'
0.4750
0.2591
0.6145
0.0017
ili - •• "Xs
0.0696
0.0063
0.3604
0.4489
0.0443
15.1752
1.1824
2.2194
0.8536
0.0696
0.0443
0.0759
12.6776
*r'*~**L''-"-r '
573.4885
37179.1542
970.2178
0.9232
5.5326
Ambient
Bioavailable
Cone. In Plume
(mg/l)
/ « ~^~ „ y^ ,
8.94E-05
4.88E-05
1.16E-04
3.15E-07
"*^-SW^T ^"> ""=«- ^*
1.44E-06
2.14E-08
8.82E-06
4.23E-07
1.08E-06
9.71 E-05
1.40E-06
8.36E-06
6.91 E-06
1.70E-06
1.08E-06
1.86E-06
9.79E-06
fe: „ *•<-" *r
"is - J«->
8.40E-02
5.44E+00
1.42E-01
1.35E-04
8.10E-04
Average
Exposure
Cone.
(mg/l)
-»„--/ 7" '
2.96E-07
1.62E-07
3.84E-07
1.04E-09
* s *Srti '~\
4.78E-09
7.10E-11
2.92E-08
1.40E-09
3.59E-09
3.22E-07
4.65E-09
2.77E-08
2.29E-08
5.64E-09
3.59E-09
6.16E-09
3.24E-08
" ~-v r ~
^.
2.78E-04
1.80E-02
4.71 E-04
4.48E-07
2.69E-06
Fish Tissue
Concentration
(mg/kg)
5>^ ~ - "X. ...
1.26E-04
4.85E-06
1.01E-03
1.46E-09
_., _ - __^
3.06E-07
3.91 E-07
2.92E-08
6.16E-08
6.82E-08
5.15E-06
1.67E-07
1.36E-06
1.08E-06
2.71 E-08
1.80E-09
7.14E-07
1.52E-.06
" *v
6.43E-02
A-64
-------
Recreational Finfish Health Risks - AK
BAT Option 2
Pollutant Name
Priority PbllutanttJirginics'""
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants," Metals'™
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
Iron
Tin
Titanium
Fish Tissue
Concentration
(mg/kg)
1.26E-04
4.85E-06
1.01E-03
1.46E-09
3.06E-07
3.91 E-07
2.92E-08
6.16E-08
6.82E-08
5.15E-06
1.67E-07
1.36E-06
1.08E-06
2.71 E-08
1.80E-09
7.14E-07
1.52E-06
-
6.43E-02
99th
Percentile
Intake
(mg/kg-day)
;~?
3.43E-07
1.32E-08
2.74E-06
3.96E-12
' s. '*"
8.29E-10
1.06E-09
7.93E-11
1.67E-10
1.85E-10
1.40E-08
4.54E-10
3.68E-09
2.92E-09
7.35E-11
4.87E-12
1.94E-09
4.14E-09
1.74E-04
99th
Percentile
Hazard
Quotient
(mg/kg-day)
^ 4
1.71E-05
3.29E-07
6.61 E-1 2
V
8.29E-07
3.53E-06
1.98E-07
5,57E-07
4.66E-06
1.46E-07
1.47E-08
9.74E-10
2.42E-05
1.38E-08
k y s*
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
" .. j
ff
4.78E-11
- ' ,< *
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
/ ,
$
1.11E-10
' ;.
A-65
-------
APPENDIX 5-4
GULF OF MEXICO
COMMERCIAL FISHERIES
HUMAN HEALTH RISK ANALYSIS
A-66
-------
-------
Commercial Shrimp Health Risks - COM
Shallow Water Development Model Well
Baseline
Pollutant Name
Naphthalene
Fiuorene
Phenanthrene
Phenol
J?
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
.ead
Nickel
Selenium
Silver
Thallium
Zinc
;NQii:^onyerftio«|(|P!oilut^fte . 3
Aluminum
Barium
Iron
"in
Titanium
Shrimp
Tissue
Cone.
(mg/kg)
- ~^_ ~ -. -5w
9.82E-04
1.93E-05
1.11E-03
1.62E-06
, •,;;-„',,"„>-.«,
2.99E-05
3.82E-05
2.86E-06
6.02E-06
6.67E-06
5.03E-04
1.64E-05
1.33E-04
1.05E-04
2.65E-06
1.75E-07
6.98E-05
1.49E44
*v32ft«"
1.05E+00
99th
Percentile
Intake
(mg/kg-day)
"^ i. .,"' " ",
1.16E-08
2.29E-10
1.32E-08
1.92E-11
"~Z "$££&.* ',
3.54E-10
4.53E-10
3.39E-11
7.14E-11
7.90E-11
5.97E-09
1.94E-10
1.57E-09
1.25E-09
3.14E-11
2.08E-12
8.27E-10
1.77E-09
^i'%*till
1.25E-05
99th
Percentile
Hazard
Quotient
(mg/kg-day)
^ ^ JI^>~'~
5.82E-07
5.72E-09
3.20E-11
~i r ^^,V««, " '
3.54E-07
1.51E-06
8.47E-08
2.38E-07
1.99E-06
6.24E-08
6.28E-09
4.16E-10
1.03E-05
5.89E-09
,,it)-.'.^ .^5
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
-r--^,
— ^T4 i fe™^
A-67
-------
Commercial Shrimp Tissue Pollutant Concentrations - GOM
Shallow Water Development Model Well
Baseline
_
Pollutant Name
—"Annual
"Pollutant
• Loadings
(mg)perSWD
Model SBF
Well
Priority Pollutant Orgamcs^^T*"
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Poliutants7!letaJsC2
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
Iron
Tin
Titanium
1.60E+05
8;74E+04
2.07E+05
5.64E+02
2.35E+04
2.13E+03
1.22E+05
1.51E+05
1.49E+04
5.12E+06
3.99E+05
7.49E+05
2.88E+05
2.35E+04
1.49E+04
2.56E+04
4.28E+06
. ,iiU.
1.93E+08
1.25E+10
3.27E+08
3..11E+05
1.87E+06
Pollutant
Sediment
Concentration
(mg poll/kg sed)
__ -• rf"
2.41 E-03
1.32E-03
3.12E-03
8.49E-06
?- -x<
3.53E-04
3.21 E-05
1.83E-03
2.28E-03
2.25E-04
7.70E-02
6.00E-03
1.13E-02
4.33E-03
3.53E-04
2.25E-04
3.85E-04
6.43E-02
^fr
s. $•
2.91 E+00
1.89E+02
4.92E+00
4.69E-03
2.81 E-02
Estimated
Pore Water
Cone.
(mg/l)
",
2.10E-04
5.85E-05
3.85E-05
1.05E-04
\~ ' -
4.24E-05
6.31 E-07
2.60E-04
1.24E-05
3.19E-05
2.86E-03
4.13E-05
2.46E-04
2.03E-04
5.01 E-05
3.19E-05
5.47E-05
2.88E-04
-
4.13E-01
4.33E-01
6.99E-01
6.65E-04
3.99E-03
Shrimp
Tissue
Cone.
(nig/kg)
9.82E-04
1.93E-05
1.11E-03
162E-06
2.99E-05
3.82E-05
2.86E-06
6.02E-06
6.67E-06
5.03E-04
1.64E-05
1.33E-04
1.05E-04
2.65E-06
1.75E-07
6.98E-05
1.49E-Q4
i >>
1.05E+00
A-68
-------
Commercial Shrimp Tissue Pollutant Concentrations - GOM
Shallow Water Development Model Well
BAT Option 1
Pollutant Name
Annual
Pollutant
Loadings
(mg)perSWD
Model SBF
Well
iiiftffiSHiinpifli^jiis._. *_•*:•_ J*
Naphthalene
Fluorene
Phenanthrene
Phenol
ip^i;;®iptnits;iMetals<£l
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
.ead
Nickel
Selenium
Silver
Thallium
Zinc
Mon-pon^sritiQniil'Collutants
Aluminum
Jarium
Iron
Tin
Titanium
5.42E+04
2.96E+04
7.02E+04
1.91E+02
;- "^ -, """'- 4£
7.94E+03
7.22EH-02
4.11E+04
5.12E+04
5.05E+03
1.73E+06
1.35E+05
2.53E+05
9.74E+04
7.94E+03
5.05E+03
8.66E+03
1.45E+06
>.
6.55E+07
4.24E+09
1.11E+08
1 .05E+05
6.32E+05
Pollutant
Sediment
Concentration
(mg poll/kg
sed)
^ *3- "" ™^* ?-s s~
8.16E-04
4.45E-04
1.06E-03
2.87E-06
~" v .'• --r.*
1.19E-04
1.09E-05
6.19E-04
7.71 E-04
7.60E-05
2.61 E-02
2.03E-03
3.81 E-03
1.47E-03
1.19E-04
7.60E-05
1.30E-04
2.18E-02
*„ •- --, » > • 's
9.85E-01
6.39E+01
1.67E+00
1.59E-03
9.50E-03
Estimated
Pore Water
Cone.
(mg/kg)
V ",,
7.10E-05
1.98E-05
1.30E-05
3.56E-05
«•-
1.44E-05
2.14E-07
8.79E-05
4.21 E-06
1.08E-05
9.68E-04
1.40E-05
8.33E-05
6.89E-05
1.70E-05
1.08E-05
1.85E-05
9.75E-05
"' -„, ~~*^,
1.40E-01
1.46E-01
2.37E-01
2.25E-04
1.35E-03
Shrimp
Tissue
Cone.
(mg/kg)
t, i f-~ -
3.33E-04
6.53E-06
3.77E-04
5.48E-07
< * r~
1.0TE-05
1.29E-05
9.67E-07
2.04E-06
2.26E-06
1.70E-04
5.53E-06
4.49E-05
3.56E-05
8.96E-07
5.94E-08
2.36E-05
5.04E-05
^ ' ?•'
3.55E-01
A-69
-------
Commercial Shrimp Tissue Pollutant Concentrations - GOM
Shallow Water Development Model Well
BAT Option 1
Pollutant Name
Priority.PoIlutaht Oirganics,;
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metals
Cadmium
Mercury
Antimony
Arsenic
Beryiium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
Iron
Tin
Titanium
Shrimp
Tissue
Cone.
(mg/kg)
3.33E-04
6.53E-06
3.77E-04
5.48E-07
1.01E-05
1.29E-05
9.67E-07
2.04E-06
2.26E-06
1.70E-04
5.53E-06
4.49E-05
3.56E-05
8.96E-07
5.94E-08
2.36E-05
5.04E-05
3.55E-01
99th
Percentile
Intake
(mg/kg-day)
K ***>.
5.72E-09
1.12E-10
6.48E-09
9.42E-12
- , ^ ,
1.74E-10
2.22E-10
1.66E-11
3.51 E-11
3.88E-11
2.93E-09
9.52E-11
7.72E-10
6.12E-10
1.54E-11
1.02E-12
4.06E-10
8.67E-10
6.11E-06
99th
Percentile
Hazard
Quotient
(mg/kg-day)
*''
2.86E-07
2.81 E-09
1.57E-11
'/• ^
1.74E-07
7.41 E-07
4.16E-08
1.17E-07
9.77E-07
3.06E-08
3.08E-09
2.04E-10
5.08E-06
2.89E-09
~ s
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
• -
* s"
1.00E-11
~* -
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
'_ ' ••
2.34E-11
"
A-70
-------
Commercial Shrimp Tissue Pollutant Concentrations - GOM
Shallow Water Development Model Well
BAT Option 2
Pollutant Name
Annual Pollutant
Loadings (mg)
per SWD Model
SBFWell
irHiPi^iwi^^aiiicF ;r* s -T.' - i
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority PollutantC Meitfs
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Aluminum
Barium
Iron
Tin
Titanium
4.99E+04
2.72E+04
6.45E+04
1.76E+02
„, "*-
7.30E+03
6.64E+02
3.78E+04
4.71 E+04
4.65E+03
1.59E+06
1.24E+05
2.33E+05
8.96E+04
7.30E+03
4.65E+03
7.96E+03
1.33E+06
F. — ^ * x ,', ' ~,j*.l*
'<&rs "** ;!' —\
6.02E+07
3.90E+09
1.02E+08
9.69E+04
5.81 E+05
Pollutant
Sediment
Concentration
(mg poll/kg sed)
* '*< ""
7.50E-04
4.09E-04
9.71 E-04
2.64E-06
£''"--"*
1.10E-04
9.98E-06
5.69E-04
7.09E-04
6.99E-05
2.40E-02
1.87E-03
3.50E-03
1.35E-03
1.10E-04
6.99E-05
1.20E-04
2.00E-02J
T." ;"-*-- >=
9.06E-01
' 5.87E+01
1.53E+00
1.46E-03
8.74E-03
Estimated
Pore Water
Cone.
(mg/kg)
"•ys*, '"-
6.52E-05
1.82E-05
1.20E-05
3.27E-05
„>"-«/»-
1.32E-05
1.96E-07
8.08E-05
3.87E-06
9.92E-06
8.90E-04
1.28E-05
7.66E-05
6.33E-05
1.56E-05
9.92E-06
1.70E-05
8.97E-05
1.29E-01
1.35E-01
2.18E-01
2.07E-04
1.24E-03
Shrimp
Tissue
Cone.
(mg/kg)
~
3.06E-04
6.01 E-06
3.47E-04
5.04E-07
• " ^
9.29E-06
1.19E-05
8.89E-07
1.87E-06
2.07E-06
1.57E-04
5.09E-06
4.13E-05
3.27E-05
8.23E-07
5.46E-08
2.17E-05
4.64E-05
3.27E-01
A-71
-------
Commercial Shrimp Tissue Pollutant Concentrations - GOM
Shallow Water Development Model Well
BAT Option 2
Pollutant Name
Priority Pollutant t)rganics*:
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority PbllutantCMelals""
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
Iron
Tin
Titanium
Shrimp
Tissue
Cone.
(mg/kg)
3.06E-04
6.01 E-06
3.47E-04
5.04E-07
9.29E-06
1.19E-05
8.89E-07
1.87E-06
2.07E-06
1.57E-04
5.09E-06
4.13E-05
3.27E-05
8.23E-07
5.46E-08
2.17E-05
4.64E-05
3.27E-01
99th
Percentile
Intake
(mg/kg-day)
^x-
5.26E-09
1.03E-10
5.96E-09
8.67E-12
^
1.60E-10
2.04E-10
1.53E-11
3.22E-11
3.57E-11
2.69E-09
8.75E-11
7.10E-10
5.63E-10
1.42E-11
9.39E-13
3.73E-10
7.97E-10
-
5.62E-06
99th
Percentile
Hazard
Quotient
(mg/kg-day)
^ - "r
2.63E-07
2.58E-09
1.44E-11
,
1.60E-07
6.81 E-07
3.82E-08
1.07E-07
8.98E-07
2.81 E-08
2.83E-09
1.88E-10
4.67E-06
2.66E-09
X s
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
-, •*
**>
9.21 E-12
- -
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
^ ~*
^f * ^ r,
2.15E-11
f /
A-72
-------
Commercial Shrimp Tissue Pollutant Concentrations - GOM
Shallow Water Exploratory Model Well
Baseline
Pollutant Name
M* w*3sSCS-i3*««1tSSI??i^$»r"*1*'*^ ™A£V '-"-~l- " -'&* ™%$-~y
P^iOQtyiftoltufanfXJrgariicsii,
Naphthalene
Fiuorene
Phenanthrene
Phenol
Stg|iillllujants>,Meials :.
Cadmium
Mercury
Antimony
Arsenic ,
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Aluminum
Barium
Iron
Tin
Titanium
Annual
Pollutant
Loadings (mg)
per SWE
Model SBF
Well
xf^fj". **FSa£&e'X>*
^^e^ik-^i^s^S-;'
3.36E+05
1.83E+05
4.34E+05
1.18E+03,
',., i--^ ,' :""j
4.92E+04
4.47E+03
2.55E+05
3.17E+05
3.13E+04
1.07E+07
8.36E+05
1.57E+06
6.03E+05
4.92E+04
3.13E+04
5.36E+04
8.96E+06
4.05E+08
2.63E+10
6.86E+08
6.53E+05
3.91 E+06
Pollutant
Sediment
Concentration
(mg poll/kg sed)
^VW^j--^'' ,: xssiW'
, f^ ,, .'/? ' !-&- ,-V >
5.05E-03
2.76E-03
6.54E-03
1.78E-05
^. f
7.40E-04
6.73E-05
3.83E-03
4.77E-03
4.71 E-04
1.61E-01
1.26E-02
2.36E-02
9.08E-03
7.40E-04
4.71 E-04
8.07E-04
1.35E-01
" _/„ ..^SJ-i, 4
6.10E+00
3.95E+02
1.03E+01
9.82E-03
5.88E-02
Estimated
Pore Water
Cone.
(mg/l)
"•*"" "• T'.!?.'^." . ;
4.39E-04
1.23E-04
8.07E-05
2.20E-04
p y*£ j, ,
8.89E-05
1.32E-06
5.44E-04
2.61 E-05
6.68E-05
5.99E-03
8.65E-05
5.16E-04
4.26E-04
1.05E-04
6.68E-05
1.15E-04
6.04E-04
t »
8.66E-01
9.07E-01
1.47E+00
1.39E-03
8.36E-03
Shrimp
Tissue
Cone.
(mg/kg)
ssSJs . ''*S, ': '•
2.06E-03
4.04E-05
2.33E-03
3.39E-06
^4 ^
6.26E-05
8.00E-05
5.99E-06
1.26E-05
1.40E-05
1.06E-03
3.43E-05
2.78E-04
2.20E-04
5.55E-06
3.68E-07
1.46E-04
3.12E-04
- - , '*
2.20E+00
A-73
-------
Commercial Shrimp Health Risks - GOM
Shallow Water Exploratory Model Well
Baseline
Pollutant Name
Priority; PplluiantiJQfganicsii
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority. Pollutaijts, Metals '__
Cadmium
Mercury
Antimony
Arsenic
Beryiium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants,
Aluminum
Barium
ran
"in
Titanium
Shrimp
Tissue
Cone.
(mg/kg)
2.06E-03
4.04E-05
2.33E-03
3.39E-06
6.26E-05
8.00E-05
5.99E-06
1.26E-05
1.40E-05
1.06E-03
3.43E-05
2.78E-04
2.20E-04
5.55E-06
3.68E-07
1.46E-04
3.12E-04
2.20E+00
99th
Percentile
Intake
(mg/kg-day)
1.37E-08
2.69E-10
1.55E-08
2.25E-11
-
4.16E-10
5.32E-10
3.98E-11
8.39E-11
9.29E-11
7.01 E-09
2.28E-10
1.85E-09
1.47E-09
3.69E-11
2.44E-12
9.72E-10
2.08E-09
%s'
1.46E-05
99th
Percentile
Hazard
Quotient
(mg/kg-day)
!* ff_
6.84E-07
6.72E-09
3.76E-11
/•
4.16E-07
1.77E-06
9.95E-08
2.80E-07
2.34E-06
7.33E-08
7.37E-09
4.89E-10
1.21E-05
6.92E-09
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
_ * ^ ' » i
*-/ i
2.40E-11
-
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
/fzy
/
5.59E-11
^< * ^<^
A-74
-------
Commercial Shrimp Tissue Pollutant Concentrations - GOM
Shallow Water Exploratory Model Well
BAT Option 1
Pollutant Name
Annual
Pollutant
Loadings
(mg) per
SWE Model
SBF Well
Naphthalene
Fluorene
Phenanthrene
Phenol
Pri6Vity4Pbllutants,"Mctafe "
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
liSi-Cpn^eritilonal Pjolfuiants
Aluminum
Barium
Iron
Tin
Titanium
1.14E+05
6.20E+04
1.47E+05
4.00E+02
- "^*V •-'"''
1.66E+04
1.51E+03
8.62E+04
1.07E+05
1.06E+04
3.63E+06
2.83E+05
5.31 E+05
2.04E+05
1.66E+04
1.06E+04
1.82E+04
3.03E+06
3.01 E-05
4.47E-07
1.84E-04
8.82E-06
2.26E-05
2.03E-03
2.93E-05
1.74E-04
1.44E-04
3.55E-05
2.26E-05
3.88E-05
2.04E-04
*" ,» ~" **
2.93E-01
3.07E-01
4.96E-01
4.72E-04
2.83E-03
Shrimp
Tissue
Cone.
(mg/kg)
-
6.97E-04
1.37E-05
7.90E-04
.1.15ET06
- • .,
2.12E-05
2.71 E-05
2.03E-06
4.27E-06
4.73E-06
3.57E-04
1.16E-05
9.41 E-05
7.46E-05
1.88E-06
1.24E-07
4.95E-05
1.05E-02
*' ' ^ . * 1
7.40E+01
A-75
-------
Commercial Shrimp Health Risks - COM
Shallow Water Exploratory Model Well
BAT Option 1
Pollutant Name
Priority PollutanfOi-ig.anics-f:^"
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority Pollutants, Metals ,
Cadmium
Mercury
Antimony
Arsenic
Beryiium
Chromium
Copper
.ead
Nickel
Selenium
Silver
Thallium
Zinc
NontConventionaliPoHutant.Sc-
Aluminum
Sarium
Iron
Tin
Titanium
Shrimp
Tissue
Cone.
(mg/kg)
6.97E-04
1.37E-05
7.90E-04
1.15E-06
2.12E-05
2.71 E-05
2.03E-06
4.27E-06
4.73E-06
3.57E-04
1.16E-05
9.41 E-05
7.46E-05
1.88E-06
1.24E-07
4.95E-05
1.05E-02
7.40E+01
99th
Pe'rcentile
Intake
(mg/kg-day)
*
6.73E-09
1.32E-10
7.63E-09
1.11E-11
> - _
2.04E-10
2.61 E-10
1.96E-11
4.12E-11
4.57E-11
3.45E-09
1.12E-10
9.08E-10
7.20E-10
1.81E-11
1.20E-12
4.78E-10
1.01E-07
, -
7.14E-04
99th
Percentile
Hazard
Quotient
(mg/kg-day)
-
3.36E-07
3.30E-09
1.85E-11
' >.
2.04E-07
8.71 E-07
4.89E-08
1.37E-07
1.15E-06
3.60E-08
3.63E-09
2.40E-10
5.97E-06
3.38E-07
„* &
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
1.18E-11
• -.
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
'•-, ',
/ ^
2.75E-11
' /
•\
A-76
-------
Commercial Shrimp Tissue Pollutant Concentrations - GOM
Shallow Water Exploratory Model Well
BAT Option 2
Pollutant Name
Annual
Pollutant
Loadings (mg)
per SWE
Model SBF
Well
Priority iPoIlufaftf Orgahlcs',. "'" .:*" ^
Naphthalene
Fluorene
Phenanthrene
Phenol
pio1llp»olKla%tsrMefeals HT»
Cadmium
Mercury •
Antimony
Arsenic „•• :
Berylium
Chromium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
Iron
Tin
Titanium
1.04E+05
5.70E+04
1.35E+05
3.68E+02
' •-
1.53E+04
1.39E+03
7.93E+04
9.87E+04
9.74E+03
3.34E+06
2.60E+05
4.88E+05
1.88E+05
1.53E+04
9.74E+03
1.67E+04
2J9E±06
tfi ~. «~-" __^
1.26E+08
8.18E+09
2.13E+08
2.03E+05
1.22E+06
Pollutant
Sediment
Concentration
(mg poll/kg sed)
- "~
1.57E-03
8.57E-04
2.03E-03
5.53E-06
/ - *'"" ' , ^
2.30E-04
2.09E-05
1.19E-03
1.49E-03
1.46E-04
5.02E-02
3.91 E-03
7.34E-03
2.82E-03
2.30E-04
1.46E-04
2.51 E-04
4.20E-02
' -z^.^" •. T>"> ^
1.90E+00
1.23E+02
3.21 E+00
3.05E-03
1.83E-02
Estimated
Pore Water
Cone.
(mg/kg)
/ r *"'
1.37E-04
3.81 E-05
2.51 E-05
6.85E-05
" \*V7 ' ^
2.77E-05
4.11E-07
1.69E-04
8.11E-06
2.08E-05
1.86E-03
2.69E-05
1.60E-04
1.33E-04
3.27E-05
2.08E-05
3.57E-05
1.88E-04.
2.69E-01
2.82E-01
4.56E-01
4.34E-04
2.60E-03
Shrimp
Tissue
Cone.
(mg/kg)
<• ' * ^ ~~ _^_ **
6.40E-04
1.26E-05
7.26E-04
.1.06E-06
"- -^S o
1.95E-05
2.49E-05
1.86E-06
3.93E-06
4.35E-06
3.28E-04
1.07E-05
8.65E-05
6.86E-05
1.73E-06
1.14E-07
4.55E-05
9.71 E-D5
6.85E-01
A-77
-------
Commercial Shrimp Health Risks - GOM
Shallow Water Exploratory Model Well
BAT Option 2
Pollutant Name
Priority Pollutant Organics
Naphthalene
Fluorene
Phenanthrene
Phenol
Priority PoHutanjts, Petals ;
Cadmium
Mercury
Antimony
Arsenic
Berylium
Chromium
Copper
.ead
Nickel
Selenium
Silver
"hallium
Zinc
Non-Conventional Pollutants
Aluminum
Barium
ran
'in
Titanium
Shrimp
Tissue
Cone.
(mg/kg)
6.40E-04
1.26E-05
7.26E-04
1.06E-06
1.95E-05
2.49E-05
1.86E-06
3.93E-06
4.35E-06
3.28E-04
1.07E-05
8.65E-05
6.86E-05
1.73E-06
1.14E-07
4.55E-05
9.71 E-05
6.85E-01
99th
Percentile
Intake
(mg/kg-day)
6.19E-09
1.21E-10
7.01 E-09
1.02E-11
1.88E-10
2.40E-10
1.80E-11
3.79E-11
4.20E-11
3.17E-09
1.03E-10
8.35E-10
6.62E-10
1.67E-11
1.10E-12
4.39E-10
9.38E-10
_
6.61 E-06
99th
Percentile
Hazard
Quotient
(mg/kg-day)
3.09E-07
3.04E-09
1.70E-11
*•*" f /
1.88E-07
8.01 E-07
4.50E-08
1.26E-07
1.06E-06
3.31 E-08
3.33E-09
2.21 E-10
5.49E-06
3.13E-09
/ f
O.OOE+00
Lifetime
Excess
Cancer
Risk
(30 yr
Exposure)
-
>•,
1.08E-11
Lifetime
Excess
Cancer
Risk
(70 yr
Exposure)
' 'f r,-
' £/
2.53E-11
A-78
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