abstracts for
4 Coastal & Island Mines

This paper covers research results and contruction techniques applied for marine outfall systems of three medium sized cities located on the coast of the Black Sea. The treatability and design data related to the pre-treatment and marine outfall system of a large pulp and paper mill on the same coast are presented. The preliminary studies and the development of the design criteria of the related marine outfall systems were carried out by the Department of Environmental Engineering of Istanbul Technical University. The scope of the project included oceanographic, hydrographic, and geotechnical surveys and water quality measurements. A construction method, which is widely applied in Turkey for laying of the glass reinforced pipes (GRP), has been evaluated. Pollution loads originating from the land based sources have been given and their probable environmental impacts in the receiving water body have been discussed.

Studies have been made of the feasibility of discharging residue from the china clay workings in Cornwall through an outfall approximately 2 km off shore. The Paper describes the field observations and model experiments which were carried out. The model experiments enabled a prediction to be made of the probable behaviour of the residue after discharge from the outfall. However, it was impossible to predict with any confidence the effects of tidal currents in moving deposited material along the sea bed.

A scheme for disposal of fine micaceous waste from the china clay industry by pipeline to a pposition on the sea bed at 18 m depth near Dodman Point is outlined. Studies have been made on the hydrography of the area and experimental dumping of radioactive tracer carried out, and tank experiment made in order to find out how residues would be dispersed from the outfall.

Measurements of trace metals in the dissolved, suspended particulate and sediment phases of the Tamar Estuary have been combined with observations of sediment and suspended particle mobility in an interpretation of metal cycling and retention processes within the system.

Dissolved metal distributions indicate pronounced estuarine metal reactivity involving net removal onto suspended particles in the low salinity, high turbidity zone and net input from the sediment in the middle estuary. These processes are not reflected in the metal contents of suspended particulate material and superficial sediment, although the dissolved metal variations are a product of particle-water exchanges. This apparent anomaly is attributed to temporal and spatial variabilities in the composition of suspended particulate material and superficial sediment are determined by physical rather than chemical processes.

As part of an investigation of Trondheimsfjorden as a recipient, a survey of the level-bottom macrofauna was undertaken during the period June 1972 to October 1974. The survey comprised 1,580 grab samples and covered 30 stations in the main fjord and the side fjords. A total of 310 macrobenthos taxa were identified. The results indicate that the benthos of the main fjord and most side fjords are not much affected by human activity. There are, however, some restricted parts of the fjord showing effects of heavy metal pollution, artificial changes in the sediment, or hypereutrophication.

The methodology which was applied in order to determine the spreading mechanisms of a slurry released at 120 m depth in a deep water trench on he southern coast of Norway is explained. Light transmission measurements were obtained simultaneously with current and temperature recordings. The sampling methodology included both vertical profiling techniques and continuous recordings with moored instruments.

The measurements revealed the dominating mechanisms which transport portions of the particulate matter out of the deposit area. Based on these measurements, it became possible to recommend on various means to limit the amount of spreading from the deposit area.

The soft-bottom fauna are the animal communities living on and within bottom sediments. The density of individuals is frequently between 1000 and 2000 and the number of species between 60 and 90 per m2 in fjords and coastal waters. The distribution of individuals among species often tends towards a log-normal or a log series, with few species having high numbers of individuals and many species having fewer or just one individual per sample. With increasing sample size, the number of species rises more slowly than the number of individuals. The diversity curve describes the number of species as a function of the total number of individuals sampled. A high-diversity fauna shows a steeper curve than a low-diversity fauna.

Studies in a number of fjords in Norway showed negative correlation between the diversity of soft-bottom fauna and pollutant discharge amounts, proximity to discharge areas, and sediment pollutant load. An empirically based diversity classification system was developed.

There was a strong negative correlation between fauna diversity and sediment copper concentration. This is explained as a cause-effect correlation, with high copper concentrations being toxic to a number of species. The number of species is roughly halved for each ten times increase in the copper concentration. It is concluded that copper pollution has erased many species in large marine bottom areas in some Norwegian fjords.

The diversity curves may serve as criteria for the ecological effects of pollution and indicate its area of influence. These kinds of biological findings, combined with data on sediment pollutant load and discharge amounts, may form a basis for optimizing environmental protection measures.

Due to discharge of substantial amounts of heavy metals to Sorfjord for a period of 50-60 years, water, sediments and biota are severely polluted. As a consequence restrictions on human consumption of fish and shellfish have been imposed in the area. The impact may at least be traced 100 km from the source. There is another 50-100 km to the open coastal water and it is assumed that only minor amounts of pollutants are escaping Hardangerfjord and influencing the water quality of the North Sea.

Five recipients for particular mine waste have been investigated to obtain information about sedimentation pattern and secondary spreading of particles.

The sites represent:

• Recipient with steep, erodible sea bed.
• Two recipients with weak currents and rather flat bed, one in salt and one in fresh water.
• Two cases of deposition in narrow fjords with tidal currents.

Both horizontal and vertical submerged pipe outlets and discharge at shorelines are represented.

The study has been going on since 1967, in close cooperation with the mining companies involved, from which much valuable assistance and data have been obtained.

1. In Rana Fjord, discharge of 40 kg/s of mineral particles (d50 =0.03 mm) as slurry through a 20 cm diameter pipe has eroded a 50 m deep canyon in loose deposits.The final bottom slope of the canyon is 0.2 and totally eroded volume after seven years was 5-10 million m3/s. The erosion has now stopped because solid rock has been exposed.
   
   The erosion in Rana Fjord has been caused by a suspension current formed after deflection and dilution of the original, horizontal jet from the pipe. The velocity and density profiles of the suspension current are comparable with laboratory results.
2. Slurry discharged through pipes into shallow recipients form cone shaped deposits with gradually decreasing slopes. Both in Jossingfjord and Huddingvann, the maximum slopes are about 0.2 near the top of the cone, but otherways the deposit is much flatter in Jossingfjord. The reason for this difference is not known. Local slides in the deposits have been observed in Jossingfjord and are probably a regular part of the deposition mechanics.
3. The spreading of suspended sediments from submerged outlets to layers above the discharge level, depends greatly on the arrangement and operation of the outlet.
   
   Vertical drop shafts seem to give best possibilities to control this problem. It is most important, however, to avoid strong current impact on already deposited material, as this can deflect the jet upwards. The discharge point must therefore be moved as soon as the deposit grows close to the outlet.
4. Deposition from the shoreline into shallow water results in a dry bank of deposits gradually growing from the shore. The slope and stability of the bank depend on wave, current and tide conditions. The two cases that have been investigated are placed in narrow sounds where the growth of the bank constricts the tidal flows past it into cooscillating basins. It appears that the flow and the cross section and length of the constricted channel will gradually develop into a balance depending on tidal prism and amplitude, and the grain size composition of the deposit.
5. The effect of wind action on concentration of suspended particles in the surface layer has been investigated. The field data are insufficient to give more than an indication of the wind effect, but seem to fit into theoretical evaluat ions.

Volume II of the Nome Offshore Placer Project Annual Report has been prepared for Western Gold Exploration and Mining Company Limited Partnership (WestGold) to present information requested by the United States Environmental Protection Agency, Region 10 in Compliance Order No. 1088-06-12-308/309 dated June 30, 1988. Specifically, the compliance order requests:

1) Collection of data sufficient for:

• a determination of the effectiveness of different tailings discharge configurations in meeting water quality standards for turbidity and metals;
• an analysis of the effect of physical factors on plume advection and dispersion; and
• verification (with a separate set of data not used for model calibration) of the selected computer model used for predicting concentrations of metals and turbidity in the water column under different operating conditions, including water depth.

2) A report including:

• a diagram of the study area including sampling points;
• a compilation of all effluent data and water quality data;
• an analysis and discussion of the data and modeling results, including an assessment of compliance with water quality standards for turbidity and metals. This analysis shall determine (1) for each set of operating conditions (e.g., water depth, discharge depth and discharge rate), the distance from the mining vessel where water quality standards are met, and (2) the discharge configuration, including discharge pipe depth, that results in the lowest turbidity and metals concentrations at the edge of the mixing zones. The modeling analysis shall simulate the range of conditions, including operating depths, expected to be encountered during the life of the project.

Model Methods and Field Data Requirements

Before it was possible to select models to be eployed in the analysis or to determine what field data were required to prepare the models or to directly analyze the discharge configuration performance, it was necessary to understand what physical processes govern the mining spoil plume generation and dispersion.

The effluent from the mining vessel consists of a mixture of seawater and dredge spoil. The relative discharge rates of these two components must be known to characterize the effluent; therefore, pumping and production rates from the Bima were required. The weight concentration of conservative constituents of interest in the effluent such as metals was also required.

The behavior of material disposed in open water follows three phases:

1. convective descent, in which the seawater spoil mixture acts as a single cloud or density current, the movement of which is governed by the relative density of the mixture compared to the ambient receiving seawater, the magnitude and direction of local currents, and the size, geometry, location, and orientation of the discharge pipe. Oceanographic information on currents and density structure of the water column, discharge configuration information, mining vessel movement, and density of the disposed sediments are required.
2. dynamic collapse, in which the density current is broken up into smaller clouds of particles through the turbulent interaction of the clouds with the ocean currents and the interaction of the descending current with the seabottom. In this stage, oceanographic information as well as bathymetry of the seafloor and dredge position are required.
3. long-term diffusion, in which the smaller clouds of particles are transported by the ocean currents and they diffuse as individual spoil particles separate from the cloud through turbulent mixing with the ambient seawater and settle to the seafloor under gravity. In this stage, oceanographic and bathymetric information as well as size distribution and fall velocities of individual particles are important.

Turbidity in the water column downcurrent from an offshore mining vessel may originate from the dredge spoil disposal operation, transport of turbid masses of water from other locations by local currents, resuspension of material already on the seafloor through wave and/or current activity, or a combination of all of these. Information on background turbidity levels upcurrent from the mining vessel as well as the potential for resuspension of material is important.

The three-dimensional water quality and sediment plume model, Disposal From a Continuous Discharge (DIFCD), developed by the U.S. Army Corps of Engineers Waterways Experiment Station was employed to analyze the dredge spoil disposal operation. This model was designed specifically to simulate the physics of continuous disposal of dredge spoil in the marine environment. The major limitation of the model is that it does not simulate resuspension of previously deposited material. No proven model was available which handled this process as well as the others of concern. A separate model, Wave-Current Sediment Resuspension Prediction (WCSRP), developed by one of the authors of this report and used previously in the environmental impact analysis of the Endicott Development Project on the North Slope in Alaska, was used to analyze resuspension.

Field Data

Instrument moorings were deployed approximately 500 m upcurrent and downcurrent from the Bima. The upcurrent mooring (UIA) was to serve as the control and provide background data of conditions unaffected by the Bima operation. The downourrent mooring (DIA) was to provide data on the impact of the Bima operation. Each mooring contained an array of instruments which measured current speed and direction, conductivity and turbidity. A wave-tide gauge was installed on the downcurrent instrument array to measure the tide and waves. The moorings were moved several times during the survey period to follow the movements of the Bima. Total deployment time was from August 18 to October 10,1988.

In addition to the fixed instrument arrays, which provided time series data over long periods of time from a single location, portable instruments were used to make physical transects of the dredge spoil plume to define its shape and extent. Transect surveys were made six times between August 29 and October 24, 1988. Measurements during the transect surveys included relative (rather than absolute) turbidity, conductivity, temperature, pH, and dissolved oxygen content.

This intensive data collection program was performed as a supplement to the plume monitoring carried out in compliance with the National Pollutant Discharge Elimination System (NPDES) permit. The NPDES program data are compiled in Volume I (Section 3.3.1 and Appendix F).

Sediment traps were deployed throughout the study area to collect samples of sediment deposited on the seafloor during the study period. These samples were used to determine the grain sizes of the most recently sedimented material for calibration of the resuspension model. The sediments collected far from the mining vessel were fine grained materials in the fine sand to silt ranges. Nearer the Bima location, sediments were coarser grained though still in the fine sand and silt size ranges. Grab samples were also collected in the vicinity of the mining vessel operation to determine composition of materials that may be resuspended by the Bima discharge. These samples varied from mostly fine sand to mostly silt. Grain sizes of sediments sampled directly from the mining vessel bucket lines were nearly equally distributed among gravel, sand, and silt fractions.

Oceanographic conditions in the area were dominated by tidal currents which were predominantly oriented around the east-west direction, with currents to the west being most common.

Three high wave events associated with storms were observed during the monitoring program, during the periods of August 23 through 25, September 13 through 16, and September 31 through October 1, 1988. Increased turbidiy levels reflected the resuspension of bottom sediments by wave action during these events.

During collection of plume transect data, it was observed that natural resuspension of bottom sediments by longshore currents caused the waters along the coastline between Nome and the Bima to be more turbid than waters offshore. Oceanographic conditions greatly affected the width of the plume with high wave activity and variable current direction and magnitude tending to disperse the plume. Changes in the plume width or appearance as defined by the transect data which were caused by changes in the discharge configurations could not be separated from those caused by variations in the oceanographic conditions.

Review of the NPDES permit effluent monitoring data (collected by WestGold personnel) revealed a high degree of variability in readings taken at essentially the same location and time. The variability of the discrete samples taken in the turbidity plume can be attributed to both the physics of the plume dispersion process and sampling and analytical techniques.

Eddies are shed from the discharge plume in the immediate vicinity of the mining vessel both by ambient currents and the relative velocity of descent of the plume through the water column. These eddies create clouds of suspended sediment that are not uniform in concentration. A discrete grab sample taken in the water column may or may not have been in one of the clouds and the concentration in the cloud may or may not have been indicative of the average concentration created at a particular point by the plume.

Variability of current direction with depth was observed in the field data and may have caused the plume to be at a different location at depth than it appeared at the water surface. This may have led to sampling outside of the plume. Sampling near the seafloor during periods of wave activity may have led to impact with the seafloor and resuspension of sediment by the sampling device which could have led to erroneously high readings. Errors of these types could be inferred, though not clearly proven, from the data.

Samples were analyzed using a nephelometer which measures turbidity optically. Contamination of the lens or sample container may have led to erroneously high readings. This type of systematic error was not, however, apparent in the data.

The large variability in measured turbidity may be greatly reduced by analyzing continuously recorded data. Such data may be averaged over reasonably short time periods, for instance each hour, to give a more realistic picture of the water quality conditions associated with the mining vessel operation.

Discharge configurations employed during the 1988 season were compared on the basis of the field data. All four configurations employed a pair of 500 mm (20 in.) diameter discharge pipes extending varying distances beneath the water surface, with or without deflector plates at the termination of the pipes. The evaluation was hampered by the limited time periods during which different configurations operated under similar mining operation and environmental conditions. On the basis of turbidity data, no single configuration could be selected as the best. Trace metal data taken at the edge of the 100 m mixing zone (D100) could not be used in the comparison because most of the data collected were either below background levels or below the detection limits of the instruments used to analyze the samples.

Model Analyses

The sediment resuspension model (WCSRP) was successfully calibrated using DIA data from a time period when the Bima was not in operation. The calibrated model was used to predict turbidity generated by resuspension of bottom sediments for the same environmental conditions experienced in the Bima's area of operation for the time period from August 18 through October 10, 1988. Comparison of predicted turbidities with observed turbidities at the downcurrent instrument array revealed good correlation during the time periods the Bima was not operating and priods of storms and high levels of wave activity. During the other periods, the model did not predict significant turbidity associated with natural resuspension of sediments. The turbidity observed during these periods was associated- either with the Bima operation and/or movement of a turbid water mass into the area by local currents. As a result of these analyses, only time periods where natural resuspension was minimal as predicted by WCSRP, were selected for calibration and verification of the plume model, DIFCD.

The DIFCD model was calibrated and verified for turbidity prediction with different data sets for conditions of two 500 mm (20 in.) diameter pipes extending different distances beneath the water surface, both with and without deflectors on their ends:

Discharge Depth Below Surface (m)	Deflectors
4.6	No
1.5	No
1.5	Yes
7.0	Yes

Verification of the configuration with pipes extending 7.0 m (23 ft) beneath the water surface was not considered adequate due to limited field data.

The model was not calibrated to simulate dilution of trace metals in the effluent water since the field data were generally either below background levels or detection limits and therefore inadequate for calibration purposes.

The DIFCD model was then used to compare the following discharge configurations on the basis of both turbidity and trace metals concentrations for varying combinations of effluent discharge, silt content, and current speed:

Water Depth (m)	Discharge Depth Below Surface (m)	Deflectors
10	1.5	No
10	15	Yes
18	1.5	No
18	1.5	Yes
18	4.6	No
22	1.5	Yes

The predictions of turbidity were considered absolute within the calibration and verification precision of the model. The metals concentration predictions were considered relative values at best since the data had been inadequate for model calibration and verification.

In shallow water the 1.5 m vertical pipes with deflectors gave marginally better water quality. In deep water, there was no clear cut best configuration. The differences in results were on the same order of magnitude as the predictive accuracy of the model.

Nine specific days during the 1988 season when turbidity levels measured at the edge of the 500 m mixing zone exceeded the criterion of 25 NTU above background were analyzed using DIFCD to predict at what distance from the mining vessel the criterion was met. The maximum distance was 900 m and the average 725 m. A detailed summary of these results is included in Table 6.2.2-1.

The same analysis was not applied to trace metals since most of the field data collected at 100 m from the mining vessel were at or below the background levels or below detection limits of the instruments used in the analysis.

The DIFCD model was used to predict the distance at which turbidity would be within the 25 NTU above background criterion for a number of other operating, sediment, and current conditions. The maximum distanc predicted for these conditions was 1,065 m and the average 760 m. A detailed summary of these results is included in Table 6.2.2-2.

The DIFCD model was also used to predict turbidity levels that might result from different scenarios that the Bima might be operated under in the future. Two 500 mm (20 in.) diameter pipes extending 1.5 m (5 ft) below the water surface were selected for the analysis. The results generally indicated that for low silt contents of the dredge spoil (less than 6 percent of the solids) and effluent discharges less than 50 MGD, turbidity generated by the Bima operation will be less than 25 NTU above background levels at 500 m from the mining vessel. With high silt contents (15 percent) and higher effluent discharge rates, the value could reach as high as 162 NTU. A table presenting the turbidity which may result at varying distances from the mining vessel for various combinations of environmental and operating parameters is included in this report (Table 6.2.3-2). These data may be used in planning future operations and monitoring programs to assure compliance with the NPDES discharge permit.

Various combinations of environmental and operating parameters is included in this report (Table 6.2.3-2). These data may be used in planning future operations and monitoring programs to assure compliance with the NPDES discharge permit.

A National Pollutant Discharge Elimination System (NPDES) draft permit was issued to Western Gold Exploration and Mining Company, Limited Partnership (WestGold) for operation of the BIMA mining vessel offshore of Nome, Alaska. The NPDES draft permit proposed limitations on BIMA operation which would make its operation not economically feasible. Engineering Hydraulics, Inc. (EHI) conducted evaluations of the BIMA tailings disposal system in 1988 and 19891,2,3. The environmental Protection Agency (EPA) interpolated between curves describing a worst case performance scenario presented in these previous study reports to establish the proposed limits on BIMA operation.

WestGold commissioned EHI to conduct additional evaluations of the BIMA tailings disposal system using an expanded data base, and data edited to exclude conditions that would not be representative of normal operation (i.e. storm conditions) to provide a more realistic set of guidelines for BIMA operation.

The data base for the particle size distribution of dredged material was expanded to include 411 bore-hole samples collected throughout the proven ore reserve in place of the 20 dredge bucket grab samples used for previous analyses. The data were analyzed to correlate silt content with water depth. Current speed data used for previous analyses were re-analyzed to exclude abnormally high currents that would only be typical of storm conditions during which the dredge would not be operating.

The DIFCD numerical model was used to predict the turbidity rise downstream from the BIMA using a matrix of input parameters developed from the revised data base. Nomographs were developed from the model output to be used to manage dredge operation to meet compliance with water quality standards at various mixing zone distances and for varying environmental conditions. These are included in Appendix D with an explanation of their use.

It was found that for the normal range of dredge production rates (400 to 1200 m3/hr), the effects of changes in production rate on the turbidity were small when compared to the impact of varying environmental conditions. For the average silt content found in each depth range combined with the average current speed, the model predicted that the dredge can operate at its maximum capacity of 1200 m3/hr without exceeding water quality standards at the edge of a 500 m mixing zone. A 1000 m mixing zone is required for compliance if currents are maximum in combination with average silt content. If silt content is high, regardless of current speed, a 1200 m mixing zone is sufficient, with an exception. At depths in the 20 m range, the naturally occurring silt contents are exceptionally large, increasing the mixing zone requirement to 1400 m with average currents. For the combination of maximum currents, maximum silt content and 20 m depth, these is no feasible mixing zone size.

The WestGold Marine Placer Mining Operation at Nome, Alaska, has an environmental protection programme of considerable interest to Canadian regulatory agencies. The programme was created in part under permit requirements, and in part from a WestGold initiative. It encompasses mitigation measures to constrain turbidity; and environmental monitoring of (1) water quality, (2) a major fishery resource (the Red King Crab), (3) seabed physical and biological disturbance and (4) natural rehabilitation. To date, no additional protective action based on environmental trends monitored have been required.

WestGold has organized an inter-agency project review committee which meets quarterly to review the environmental protection programme. This committee has representatives of federal, state, municipal, native and environmental agencies. There is an annual meeting of this group in January each year, at which the previous years operations are reviewed and plans for the following year presented.

This U.S. Bureau of Mines publication presents a case study of the processes used in permitting the Nome Offshore Placer Project, a gold mining project offshore Nome, Alaska which operated from 1985 through 1990. The mining project, developed by Western Gold Exploration and Mining Company, Limited Partnership (WestGold), used the BIMA, which was at the time the argest bucketline mining vessel in the world, to dredge gold from the ocean floor.

This case study reviews the permitting process from the regulators' and industry's perspectives, as well as characterizing the efficiencies and inefficiencies associated with this case. The Federal, State and local laws applicable to the Nome Offshore Placer Project are identified, agency jurisdiction and interagency relationships are explored, and the chronology of the permitting process is examined. The regulatory authorities for both environmental monitoring and post-mining monitoring are delineated. Significant milestones affecting the project and required regulatory submittals are also included.

The case study of the Nome Offshore Placer Project is detailed with respect to agency involvement and coordination, approaches to permitting from both the regulators' and developer's perspective, environmental issues, and permit stipulations which were unique to the project. The advantages and disadvantages of these topics are discussed.

From 1985 to 1991 the Nome region of Norton Sound supported the only successful offshore gold mining operation in the United States. During its operation, WestGold conducted the most extensive evaluation of marine placer deposits in the world. This required the acquisition of thousands of samples of the seafloor. However, during the 7-year WestGold project, no suitable survey method existed for the rapid acquisition of seafloor samples that could be used for both geological interpretation and biological assessment.

The seafloor samples obtained during the WestGold project intended for geological or metallurgical analysis were generally unsuitable for biological work and were both time consuming and expensive to obtain. The biological samples collected by divers were not suitable for geological work and were labor intensive and difficult to quantify. Also, divers are the only reliable method for sampling coarse-grained substrates for biological purposes. The use of divers is not efficient or cost-effective and has definite depth and sea-state limitations.

The major goal of this study was to test a sampler that would be cost effective in obtaining samples suitable for geological and biological analysis. One such device was a hydraulically activated benthic sampler developed by the Centre for Cold Ocean Resources Engineering (C-CORE) and was designed for geological and biological evaluation of marine placer deposits and mine tailings sites. This sampler also has the added attraction of taking two samples at a time (i.e., duplicates); this has a definite statistical advantage. The sampler was to be evaluated for the following applications:

• Quantitative sampling in glacial marine placers for geological and metallurgical physical characterization.
• Quantitative sampling n submarine tailings deposits to characterize tailings materials, physical restabilization, and biological recolonization.
• Concurrent quantitative biological sampling in coarse-grained sediments such as gravels and cobbles.

In so doing, another year of benthic biological monitoring would be added to the database.

ENSR Consulting and Engineering (ENSR) located in Anchorage, Alaska, orchestrated a sampling program funded by a number of agencies, combining the needs of these two programs. The project was jointly funded by the Marine Minerals Technology Center, Continental Shelf Division; the U.S. Bureau of Mines (Juneau office); the Minerals Management Service; and the Alaska Science and Technology Foundation. ENSR was assisted by the University of Alaska Fairbanks Institute of Marine Science (UAF/IMS) and North Pacific Biological Research (NPBR) in Fairbanks, Alaska.

The field work was performed in early June 1993. Two mined stations, one mined in 1986 and the other mined in 1987, were sampled and compared to stations not affected by mining (control stations). Sand and cobble substrates were sampled at both mined and unmined stations. Sample stations were located with the aid of a Global Positioning System and established station water depths.

Divers obtained benthic samples of the sand substrate by pushing a collecting frame into the sediment. The sediment within the frame was vacuumed into a collection bag attached to a suction device.

For cobble substrate, a different type of benthic sampler was used. Attached to one side and perpendicular to the circular collecting frame was a second frame with a sample bag, which was used for hand placement of large rocks. The rest of the collecting frame remained open to facilitate hand or suction collection of the substrate.

Samples were preserved in the field and then transported to the UAF/IMS lab for sorting, identification, and enumeration.

Sediments for grain size analysis were collected immediately adjacent to the benthic sampling frame. This was to help chracterize the physical environment where the infaunal samples were obtained.

The hydraulic bucket sampler was deployed from the support boat via a davit and hydraulic winch. The bucket sampler was operated by C-CORE personnel assisted by NPBR and ENSR personnel.

The invertebrate fauna captured by the samplers were identified to the genus level. Standardization of the data sets from previous years was necessary to aid between-year comparisons.

A number of analytical tools was used to investigate community structure. k-Dominance curves, a technique to detect natural, physical, biological, and pollution-induced disturbance on marine benthic communities, were the primary tool to detect disturbance in the benthos. In addition, comparisons of a number of diversity indices were used to assess community structure and changes therein. Margalef's species richness index was used, as well as Simpson's diversity index (D) and the Shannon-Weaver diversity index (H').

Conclusions drawn from this study pertaining to recolonization and benthic community structure:

• Further evidence was found that recolonization of benthic communities after mining disturbance to their original structure may not occur; instead, a somewhat different assemblage than the original species may result,
• The time required for recolonization of dredged areas to comparable density, biomass, and number of taxa, as in control sites is still unknown. Mined sites (7 years after mining) are still showing signs of community stabilization.

Conclusions drawn pertaining to the bucket sampler testing program were:

• The sampler tended to fall over on an uneven or sloping bottom. The sampler had to hit squarely or nearly so to work properly. It also tended to fall over when it landed on large cobble or boulders.
• Penetration of the bucket was limited in cobble substrate. Also, cobbles prevented the sampler from closing completely, which led to loss of fine-grained material when the sampler was retrieved.

A complete evaluation of the bucket samplercan be found in the ENSR 1993 Field Evaluation Report for this project.

As a result of the Nome field tests, two major structural modifications have been made to the bucket sampler. Flexible rubber skirts were added to prevent wash-out of fine-grained material during retrieval, and the attachment of limiter feet has added stability and prevents the sampler from sinking in soft substrates.

These modifications were recently field tested by C-CORE and proved successful offshore of Newfoundland on a small-cobble substrate. The improved bucket sampler is now being distributed and used in Europe to sample offshore gravel deposits. Negotiations are also underway to establish distributorships in Canada, Asia, and Africa for possible application of the bucket sampler in these countries' rapidly expanding offshore mining industry.

II. TECHNOLOGY TRANSFER

Project Goals and Financial Effects

Project goals were not exceeded, but certainly met. The sampler was successfully evaluated and several design changes were recommended, which were implemented by C-CORE. However, it was discovered that the bucket sampler did not perform well in cobble substrate and a quantitative comparison of the coarse substrate sample obtained by the bucket sampler, to that obtained by a diver, was not accomplished.

The sampler has the potential to significantly reduce geological and biological data acquisition costs for marine placers. This equipment could also make the evaluation, and ultimately, mining further offshore more cost-effective and consequently more feasible. Accordingly, these developments could stimulate interest in the exploration and potential development of Alaskan marine placer resources.

This project has helped to keep the attention of the offshore mining industry focused on state and federal waters of Alaska where mineral potential is quite high. There are over 20 known marine mineral deposits in Alaska; 14 of these have been partially described by the U.S. Bureau of Mines (USBOM Open File Report 4-87,1987).

A presentation on the work and results of the study was given by Steve Jewett at the Third Annual Underwater Mining Institute technology conference held in Estes Park, Colorado, in November 1993. There was much interest expressed in the sampler at this meeting.

No follow-on funding is in place at present or is being sought. Funding for 1995 to test a larger, improved bucket sampler developed by C-CORE is presently being considered by the project team.Matching in-kind support of at least $2600 was supplied by ENSR during this project.

Benefit for Alaska

Several Alaskans worked on this project on a short-term basis. Eight personnel from the ENSR Anchorage office and several laboratory personnel from the University of Alaska Fairbanks worked on this project. In addition, a Norton Sound-based boat was chartered and rooms were rented in Nome to house the field crew.

Other investors are considering purchasing the Nome mineral leases in the summer of 1994. The new potential owners are considering mining gold in the area once again, perhaps as early as the summer of 1995. The hydraulic sampler is seriously being considered by the investors as part of their exploratory and monitoring strategies largely because of the demonstrated abilities and industry exposure since the evaluation was completed. If the sampler is adopted, this project would have measurably contributed to the rearrival of mineral extraction and continued prosperity in the Nome area.

A follow-on effort, if undertaken in 1995, would be expected to employ approximately the same number of workers in the same capacity.

Alaska's economic base was largely unaffected by this project. Future increase to the economic base could occur if the sampler helped make an offshore mining industry possible in Alaska.

Scientifically, we have added to our knowledge of benthic dynamics and recolonization as affected by mining and natural occurrences in an arctic environment. Technologically, we have suggested improvements to the bucket sampler which have already been implemented. As a result, the sampler has been successfully tested in Nova Scotia on a small cobble substrate and is beginning to earn a reputation around the world as a cost-effective method of sampling bottom substrate for mining-related activities.

SEAFLOOR STUDIES

Side Scan/Bathymetric Surveys

Fall (October 1988) bathymetric and side scan surveys were carried out in areas previousiy mined in 1985 through 1988 and at a control area. Station R6, mined in 1986, showed only minor anomalies in seafloor contours two years after being mined. Station R7, mined in 1987 and again in the 1988 mining season, showed extremely erratic seafloor contours in the 1988 mine courses with some subtle smoothing in the 1987 mined areas. The offshore 1988 mined area (D8) was indicative of recent seafloor mining.

From 1987 to 1988, the 1986 and 1987/88 Mine Areas (R6 and R7) showed an increase in coarser grained sediments and a decrease in finer grained sediments. The Control Area, which experienced no mining activity, showed 15 percent change in overall sediment types from 1985 to 1988, averaging approximately 5 percent per year. For specific substrates, fluctuations up to 8 percent (cobble substrate) occurred. This was in contrast to the 1986 Mine Area that showed a 37 percent overall change in seafloor sediment type between 1987 and 1988.

Sediments

Surface sediments were collected from both sand and cobble substrates in 1988. The 1988 sand substrate samples were similar and composed mostly of find sands. Gravels were absent from most sand substrate samples.

Cobble substrate samples consisted of that material which remained after all cobbles (764 mm; approximately 2.5 inches) were removed from the collection site. Results indicated a high degree of heterogeneity in cobble substrate within the study area.

King Crab Tracking and Movement

Monitoring of nearshore daily and short-term movements of red king crab was attempted in March 1988. Two crabs were tagged with coded sonic fish tags and tracked for a five-day period. Neither crab showed discernible movement after it was releaed, therefore no data were collected.

King Crab Catch

Catch-per-unit effort statistics were calculated for crab pots fished in March 1988 in mined and non-mined areas. As with 1987 data, there were no statistical differences between sites or between years (i.e., crab pots fished in mined areas had statistically similar catches as those of non-mined areas)

King Crab Prey Study

The king crab prey study has shown statistical similarity in crab feeding between years and between sites within years. Crabs taken from mined areas showed no difference in quantity of food or feeding activity than crabs from non-mined areas. Therefore, it appears that mining activities to date have had a negligible impact on feeding habitats of king crab offshore Nome. This is primarily due to the crabs' transitory nature, their opportunistic feeding strategy, the relatively small area impacted by dredging, and the seemingly rapid rate of recolonization of the food benthos in the impacted area.

BIOLOGICAL STUDIES

ROV Surveys

Biological observations of seafloor habitat were made with a remote operated underwater color video (ROV) camera. Surveys were made under the ice at Stations R6 and R7 in March 1988. Summer surveys were completed in June at Stations S3, C2, C3, R7 and D8. The initial objective of the ROV survey was to assess king crab density in various habitat types by actual visual counts. Only five crabs were observed, all in March. All crabs were observed at mined stations R6 and R7. Most were associated with coarse substrates. The filming at deep stations, typically in excess of 9 m (30 ft), generally revealed a lush growth of epifauna on large rock and cobble surfaces suggesting little physical disturbance. Surveys completed at shallower depths showed the same assemblages but often less robust and rarely on the tops of boulders. Often the shallow habitats appeared to be physically disturbed.

Benthos

The benthic infaunal invertebrates that characterized the sand community in 1988 were the polychaete worms Myriochele oculata and Nagelona sacculata, the clam Spisila polynyma, the sand dollar Echinarachnius parma, and the polychaetes Glycinde picta, in decreasing order of abundance. The dominant fauna in order of decreasing biomass were the polychaete worms Travesia pupa and Nephtys caeca, the sand dollar E. parma, the clam Macoma lama, and the polychaete Magelona sacculata. The population parameters of number of taxa, density, and biomass on sand substrate were highly variable between stations. The Shannon Diversity Indices at the mined stations, R6 and R7, fell between high values at deep stations C3S and S3S and low values at the shallow control stations C2S and S2S.

Benthic invertebrates which characterized the cobble community in 1988 were the brittle star Diamphiodia craterodmeta, the clam Yoldia sp., the polychaete worms Pholoe minuta and Myriochele oculata, and the ribbon worm Cerebratulus sp., in decreasing order of abundance. In terms of biomass, cobble substrates were dominated by the cockle Clinocardium californiense, the brittle star D. craterodmeta, the ribbon worm Cerebratulus sp., Yoldia and the polychaete worm G. picta. The population parameters of number of taxa, density and biomass on cobble substrate were variable, but not as variable as seen on sand substrate. Statistical tests revealed no significant differences between years for number of taxa and density at stations S2C and S3C, and biomass at stations C2C and S2C. Mined cobble substrate at stations R6C and R7C had the lowest diversity indices, indicative of few taxa but high species dominance.

Recolonization

After one year since mining at R7-sand the number of taxa, density and biomass was extremely low, resembling results seen one year after mining at R6S. After nearly two years since mining at R65, these benthic invertebrate population parameters approximate those seen at the non-mined station C35.

After one year since mining at R7-cobble the number of taxa, density and biomass was extremely low, resembling one year after miing at R6-cobble. Although it had been nearly two years since impact by mining at R6-cobble, the benthic invertebrate community here is still characterized by few taxa and low density and biomass. Recolonization of the cobble substrate appears to be lagging that of the sand, perhaps taking two or three times longer to rebound after mining.

Trace Metals in Red King Crab

In 1988, a total of 61 tissue samples from red king crab were analyzed for total recoverable trace metals. In muscle and hepatopancreas tissue, mercury and lead were found in the lowest mean metal concentrations. Cadmium also occurred at the lowest concentrations in crab muscle tissue. Zinc and copper occurred at the highest mean metal concentrations in crab muscle and hepatopancreas, respectively. All metal concentrations for red king crab were within an order of magnitude of those previously reported in scientific literature.

In addition to king crab, crab prey species were analyzed. They included two species of clams, three species of polychaetes, burrowing lugworms, sipunculid worms, spoon worms, and sand dollars. Mercury occurred at the lowest mean metal concentrations and zinc occurred at the highest mean concentrations in all crab prey species studies. All trace metal levels were of the same magnitude as those previously reported in the literature. Crab prey species exposed to 1988 dredging activities did not have significantly higher trace metal levels than organisms collected from control and subsistence areas.

TRACE METAL STUDIES

Sediments and Water

Total recoverable trace metals were analyzed in various sediment and water samples collected as part of the NPDES monitoring program. The eight trace metals analyzed were arsenic, cadmium, chromium, copper, mercury, nickel, lead and zinc.

The total recoverable trace metal values measured in sediments fell within the previously reported range of values for Norton Sound or were near background levels established during this study.

Total recoverable trace metals were anlyzed in water samples collected inside and outside the Bima turbidity plume. Results from background and effluent samples proved to be very similar indicating that the Bima mining operation was having a negligible effect on trace metal water quality.

Potential for Bioaccumulation

Trace metals were considered to be bioaccumulating if present in organismal tissues at levels greater than 1.5 times background sediment values. The only metal that showed elevated levels above background in 1988 was copper. Copper was higher than background in hepatopancreas tissue of red king crab. None of these levels of bioaccumulation were found to be unusually high when compared to trace metal concentrations reported in the scientific literature for similar animals.

This report provides an overview of the first 15 years of the Environmental Studies Program (ESP), conducted initially by the Bureau of Land Management and now as part of the Minerals Management Service. From 1973 to 1986, the ESP spent nearly $500 million on studies directed to better understand the U.S. Outer Continental Shelf (OCS) and coastal environment and to use this information to document or predict effects of offshore oil and gas activities. This report organizes the hundreds of completed studies and thousands of resulting documents into 15 study topic chapters. Each chapter (e.g., physical oceanography) cites selected studies and provides a general discussion of program objectives and results. Where appropriate, each topic is discussed by OCS Region (Alaska, Atlantic, Gulf of Mexico, and Pacific). A more comprehensive listing of ESP reports and associated publications can be found in OCSEAP (1988) and Johnson et al. (1989).

The goal of this report is to provide readers with a general account of the ESP's technical accomplishments and sources of detailed information. To understand the ESP, however, it is necessary to place this program in perspective with the entire OCS oil and gas program. The rest of this chapter provides background on the history of the ESP the OCS leasing process, and the planning processes and ongoing objectives of the ESP.

Production of fry and adults of the 1072 brood of pink salmon, Oncorhynchus gorbuscha,at Auke Creek, Alaska was conducted between a gravel incubator hatchery and natural spawning. Natural production in the Omek above the hatchery weir (estimated from hydraulic sampling) was 73,900 fry (SE: 32,800) from an estimated initial seeding of 934,065 eggs (SE: 42,811) for a survival rate of 0.079 (SE: 0.035), An estimated total of 579,000 unfed fry (SE: 25,296) were released from the hatchery for a comparable survival rate of 0.743 (SE: 0.047). Exactly 84,000 of the hatchery fry and 5,500 of the creek fry were released alter being marked by clipping fins. All adults returning to the weir were examined for marks, and some additional marks were recovered from sport and commercial fishermen: 667 marked hatchery fish and 74 marked creek fish were recovered. Estimated survival of hatchery fry to returning adult was only 0.0079 (SE: 0.0003) equal to 0.59 (SE: 0.071) the corresponding estimate of 0.0135 (SE: 0.OO16) for creek fry, which suggests that hatchery fry were inferior to creek fry in the marine environment; however, hatchery fry emigrated seaward 2 wk earlier than creek fry and may have encountered less favorable marine conditions. Survival from eggs to returning adult stage was 5.50 times (SE: 2.59) higher for hatchery fry than for creek fry because of much greater survival from egg to fry in the hatchery: the difference is not statistically significant. Hatchery fry were generally shorter but heavier than creek fry and emigrated seaward at a slightly earlier stage of development. No differences in size or time of return of adults could be traced to the incubation environment from which they came.

This is an interim report for the physical and chemical marine environment program within Boca de Quadra fjord, southeast Alaska. Details of field and laboratory techniques in use are given together with some initial data for the first two cruises run in October and December 1978. It is not possible to describe the oceanographic regime here in any detail from this limited seasonal coverage and no recommendations, except to continue the program, are given.

The deep basin water of Resurrection Bay (a single-silled fjord at 60⁰N on the south-central Alaskan coast) is renewed each summer with water having a dissolved oxygen concentration >4 ml 1^-1. Prior to 1976 >90% of the allochthonous organic carbon supply to the basin was from fish processing waste. Oxygen concentrations at the bottom were reduced to around 1 ml ^-1 during the winter, and Heggie and Burrell (1981) have computed that a quantity of carbon >5O% of the annual phytoplankton production (19 moles C m^-2 year^-1) was oxidized within the basin and near-surface sediments. Very little carbon (0.6 moles m^-1 year^-1) is removed via sediment burial in this estuary. Boca de Quadra fjord is located at approximately 55⁰N adjacent to the Alaska-British Columbia border. The annual summer flushing sequence of the deep (365 m) central basin is basically the same as in Resurrection Bay. Estimated benthic respiration (around 8 moles C m^-2 year^-1)may be supported by the in-fjord annual primary production (>12 moles C m^-2 in 1980). The mean annual input of terrigenous particulate carbon is estimated to be of the same order of magnitude as the loss rate within the basin by sediment burial (9.0 moles C m^-2 year^-1). The relatively high flux of allochthonous carbon into Boca de Quadra thus appears to consist predominantly of refractory material which does not create a significant oxygen demand within the basin.

Sixty-four algal and 115 animal species were found at seven stations in the intertidal area of Berners Bay, southeastern Alaska. Berners Bay, a turbid outwash fjord estuary, receives runoff from glaciers which terminate on land.

A heavy cover of Mytilus edulis and Fucus distichus in a wide band, with Balanus glandula or B. balanoides often growing on the Mytilus is the most conspicuous element in the intertidal area. The vertical range of the Mytilus is from 4.2 m to 0.6 m above mean lower low water. However, at one site, where starfish were apparently excluded by low-salinity water, the Mytilus extended well into the subtidal area, to about -5 m.

The northernmost range of the bryozoans Callopora corniculifera (Hincks) 1884, and C. horrida (Hincks) 1880, is extended from British Columbia to Berners Bay. The limpet Cryptobranchia concentrica Middendorff 1851, previously considered to be subtidal only, was found in the intertidal area.

The freshwater life of Coho salmon, Oncorhynchus kisutch, in Sashin Creek, Southeastern Alaska, was studied from the fall of 1963 through the summer of 1968. Additional information on age composition and fecundity of adults returning to Sashin Creek and a nearby stream was collected through the fall of 1972. Some pre-1963 data on coho salmon entering and leaving Sashin Creek were used. Weir counts and estimates of numbers of adult salmon determined from spawning ground counts and mean redd life were poor measures of the total escapement of coho salmon in Sashin Creek: an estimate made from tagging a portion of the escapement and subsequently determining tagged-to-untagged ratios of spawners on the riffles proved to be a more reliable measure. The number of spawning coho salmon varied for the years 1963 through 1967 from 162 to 916; the dominant age group was 4. The salinity of the surface water of the estuary of Sashin Creek usually is less than 10-15 0/00; bioassays of salinity tolerance indicated that coho salmon fry can survive in these salinities. In 1964, 44,000 coho salmon fry migrated to the estuary. Soon after emergence, although none of the scales collected from returning spawners in subsequent years showed less than 1 yr of freshwater residence. Survival curves constructed from periodic estimates of the stream populations of juvenile coho salmon for the years 1964-67 showed that mortality was highest in midsummer of the first year of life, when 62% to 78% of the juveniles were lost in a 1-mo period. Most coho salmon smolts migrated from Sashin Creek in late May or early June in the spring of 1968, 1,440 smolts left Sashin Creek-27% were yearlings, 59% were 2-yr-olds, and 4% were 3-yr-olds. The average fork lengths were 83 mm for yearlings, 105 mm for 2-yr-olds, and 104 mm for 3-yr-olds.

Potential impacts at Quartz Hill have been listed: water column turbidity, sea-bed deposition and smothering, fish kills and trace metal contaminations. Impact durations have been predicted, so that phased environmental monitoring, for the lifetime of the mine can be planned. Five phases are predicted: pre-operational (five? years), outfall performance and quality control (one year) and simultaneously short-term ecosystem responses (one year), delayed ecosystem responses (mine lifetime, seventy? years), and reclamation monitoring (ten? years).

For continued monitoring, there are advantages in programming and costing now, so that capital expenses can be amortised for as long as possible. Main decisions are whether to develop an in-house environmental laboratory or retain environmental consultants, and the nature of the sampling vessel (with living and laboratory facilities on board or not).

Potential impacts at Quartz Hill are: water column turbidity, sea-bed deposition and smothering, trace metal contamination and potential lethal effects of processing chemicals. Impacts have been predicted so that phased environmental monitoring for the lifetime of the mine can be planned. Five phases are predicted: pre-operational (approximately five years), outfall performance and quality control upon operations start-up (approximately one year), immediate ecosystem responses (approximately 1 year), delayed ecosystem responses (mine lifetime approximately seventy years), and reclamation monitoring (approximately 2-5 years).

In order for correct economic decisions to be made about long-term monitoring procedures, development of the monitoring program, with cost estimates, is necessary before mill operation begins. The primary decision concerning the monitoring program is whether to develop in-house environmental expertise and facilites or to retain environmental consultants. In addition, the type of the sampling vessel needed for the long-term monitoring must be investigated.

A draft interim report is presented describing the results of acute, chronic and sublethal bioassays and bioaccumulation studies completed to August, 1984 on Quartz Hill mine tailings produced by pilot plant operations. The present study endeavored to address the major environmental concerns associated with bioaccumulation and chronic sublethal effects in the context of representative ecological components using the following marine species and life history stages:

• crab (Cancer magister) zoea and juveniles
• mussel (Mytilus edulis) eggs, larvae and adults
• amphipod (Rhepoxynius abronius) adults
• clam (Macoma balthica) adults
• flatfish (Citharichthys stigmaeus) juveniles
• algae (Dunaliella tertiolecta)

Sublethal bioassays included growth of crab zoea and algae; development of crab zoea and mussel eggs and larvae; and, burrowing behaviour of clams. Acute toxicity bioassays utilized mussel larvae, amphipods and crab zoea. Bioaccumulation tests utilized juvenile crabs, adult clams and juvenile flatfish.

Comparative chemical and acute toxicity data for two sets of pilot plant tailings were developed. Tests were undertaken to demonstrate whether manganese or molybdenum, singly or in combination, could be responsible for acute toxic effects observed in Quartz Hill mine tailings.

The bioassay results confirmed the low acute toxic nature of the Quartz Hill mine tailings to be in the range of 86,000-197,000 mg/L (range of LC50 and EC50 values). The data suggested a trend to less successful development with increasing tailings concentrations, but the trend was not statistically significant because of the low numbers of surviving larvae. Further, the tailings had no demonstrable effect on clam burrowing behaviour during a 16 week exposure period. Quartz Hill mine tailings did not contribute to bioaccumulation of any metals in fish, clams or crabs over a 2 month exposure period.

Overall, sublethal effects could only be demonstrated for phytoplankton where algal growth rates, cell counts and chlorophyll concentrations were enhanced at 10,000 mg/L of tailings, but not at lower concentrations. Enhancement was attributed to an enrichment of nutrients or trace elements associated with the tailings. These sublethal effects were observed at approximately 1/10 of acute lethal concentrations. Enhanced algal growth in the presence of mine tailings does suggest the possibility for increased primary productivity in Boca de Quadra associated with tailings discharge, if tailings reach the euphotic zone at the described levels.

The acute lethal toxicity of manganese and molybdenum was additive, and mussel larvae 48-h ECSOs for manganese and molybdenum, singly or in combination, showed that these metals could account for only a very small proportion of the tailings toxicity. It is therefore probable that the observed toxicity of Quartz Hill mine tailings is the result of a mass interaction of a number of constituents. The inability of the tailings to induce inhibitory sublethal effects is important for the assessment of long-term environmental impact, and shows that representative species and life history stages can survive, grow, and actively burrow in a mine tailings environment. The results of the sublethal bioassays confirm determinations from acute lethal tests that Quartz Hill mine tailings have a relatively low toxicity.

This report describes the results of acute, chronic and sublethal bioassays and bioaccumulation studies conducted on Quartz Hill mine tailings produced by U.S. Borax's pilot plant testing. The present study endeavored to address the major environmental concerns associated with bioaccumulation and chronic sublethal effects in the context of representative ecological components using the following marine species and life history stages:

• crab (Cancer magister) zoea and juveniles
• mussel (Mytilus edulis) eggs, larvae and adults
• amphipod (Rhepoxynius abronius) adults
• clam (Macoma balthica) adults
• flatfish (Citharichthys stigmaeus) juveniles
• algae (Dunaliella tertiolecta)

Sublethal bioassays included growth of crab zoea and algae; development of crab zoea and mussel eggs and larvae; and, burrowing behaviour of clams. Acute toxicity bioassays utilized mussel larvae, amphipods and crab zoea. Bioaccumulation tests utilized juvenile crabs, adult clams and juvenile flatfish.

Comparative chemical and acute toxicity data for two sets of pilot plant tailings were developed. Tests were undertaken to demonstrate whether manganese or molybdenum, singly or in combination, could be responsible for acute toxic effects observed in Quartz Hill mine tailings.

The bioassay results confirmed the low acute toxic nature of the Quartz Hill mine tailings to be in the range of 86,000-197,000 mg/L (range of LC50 and EC50 values). Sublethal tailings concentrations of 7,500, 2,400 and 750 mg/L did not affect growth and development of crab zoea over a 30 d exposure period. The data suggested a trend to less successful development with increasing tailings concentrations, but the trend was not statistically significant because of the low numbers of surviving larvae. Further, the tailings had no demonstrable effct on clam burrowing behaviour during a 16 week exposure period. Quartz Hill mine tailings did not contribute to bioaccumulation of any metals in fish, clams or crabs over a 4 month exposure period.

Overall, sublethal effects could only be demonstrated for phytoplankton. An initial inhibition of algal growth at tailings concentrations of 1,000 and 10,000 mg/L occurred, perhaps a result of a decrease in light intensity due to particulates in the water, or the toxic effects of metals or other compounds present in the tailings slurry. This inhibition had ended by day 3 or day 4 of testing, possibly due to biological processes of acclimatization, or due to removal of the suspended particles and/or toxic compounds by precipitation or chemical complexation. In the case of the highest concentration of tailings tested (10,000 mg/L), inhibition was followed by enhancement of algal growth rates, cell counts and chlorophyll concentrations. Enhancement was attributed to an enrichment of nutrients or trace elements associated with the tailings. These latter sublethal effects were observed at approximately one-tenth of acute toxic concentrations. Enhanced algal growth in the presence of mine tailings does suggest the possibility for increased primary productivity in Boca de Quadra associated with tailings discharge, if tailings reach the euphotic zone at the described levels.

The acute lethal toxicity of manganese and molybdenum was additive, and mussel larvae 48-h EC50's for manganese and molybdenum, singly or in combination, showed that these metals could account for only a very small proportion of the tailings toxicity. It is therefore probable that the observed low toxicity of Quartz Hill mine tailings is the result of a mass interaction of a number of constituents. The inability of the tailings to induce inhibitory sublethal effects is important for the assessment of long-term environmental impact, and shows that representative species and life history stages can survive, grow, and actively burrow in a mine ailings environment. The results of the sublethal bioassays confirm determinations from acute toxicity tests that Quartz Hill mine tailings have a relatively low toxicity.

The Quartz Hill Molybdenum Project, in Southeast Alaska, was the first mining project to attempt the permitting of a submarine tailings disposal system in the United States, since the passage of the National Environmental Policy Act of 1969 and the Clean Water Act of 1977. Over $20 million was spent by the project developer in baseline data gathering and in funding the preparation of the four Environmental Impact Statements and other environmental documents required at various stages of the project between 1977 and 1988.

Because of the timing and a unique set of environmental, legal and regulatory requirements which applied to this project, innovative approaches were developed. This report describes those requirements and the developments, and gives a full historical account of the campaign for permitting submarine tailings disposal at Quartz Hill, until denial of the NPDES permit application by EPA in September 1990.

The extensive studies done for Quartz Hill suggested that under certain conditions, the selection of submarine tailings disposal can be the overall environmentally preferred alternative for a mining project. The Quartz Hill story illustrates the complexity of the existing permitting structure and points out the desirability of rationalization to achieve a more effective system.

This is the second report (for 1983) on the ongoing study on the sedimentation dynamics in Boca de Quadra. STD/ Transmissometer casts, moored sediment traps and Pb-210 sedimentation rate measurements have been employed. Suspended particulate matter (SPM) is added to the surface layer of the central basin of Boca de Quadra mainly by phytoplankton production in the "dry" season (April) and river input in the "wet" season (October). Additional input of SPM at mid-depths within the the central basin from Harten Arm and Mink Bay are believed to occur in the late fall. The possibility of SPM input into the central basin from the outer basin during the period of deep water renewal is discussed. The magnitude of the Benthic Mixed Layer (BPM) changes seasonally and appears to be a maximum in the late fall - early winter.

The escapement of pink salmon (Oncorhynchus gorbuscha) to Sashin Creek, southeastern Alaska, in 1963 was 16,757 fish, and fresh-water survival calculated from potential egg deposition and number of outmigrant fry was 20 percent. The spawning ground was divided into three areas - upper, middle and lower - for the study of density of spawners and survival of progeny. The density of spawners was highest in the middle area. Survival during spawning was low in each area. Survival between the end of spawning and the beginning of fry emergence was variable among the three areas; and survival during fry emergence was high in each area. From egg deposition to fry emergence, survival was estimated to be 31 percent in the upper area, 16 percent in the middle area, and 15 percent in the lower area.

Although the upper area was highly productive of pink salmon fry, it has had intensive spawning only in years when the density of spawners was high. When the density was low, spawners tended to concentrate in the lower area. The validity of the supposition that only highly productive spawning beds are used when escapements are small is questioned. The observations at Sashin Creek indicate that relatively large escapements help ensure complete use of productive spawning beds.

Planning the development of the Quartz Hill molybdenum open pit mine in Southeast Alaska required a number of special considerations. Located in mountainous glaciated terrain about 3.8 m (150 in.) of annual precipitation (with annual snowfall all over 10.2 m (400 in.) was a primary consideration. Mine planning included muskeg and snow removal, avalanche control, clearing timber, water quality control, dust control, seismicity, mine schedule, work force, and reclamation. Quartz Hill is in an environmentally sensitive area which has required extensive environmental baseline data collection, four Environmental Impact Statements (EIS) and a large number of permits.

This study has assessed both potential and expected physical and ecological impacts associated with submarine discharge of mill tailings at the Quartz Hill Molybdenum Project in southeast Alaska. Three basins were considered: Wilson Arm/Smeaton Bay system, Boca de Quadra central basin and Boca de Quadra inner basin. This review is intended to identify a preferred disposal option based on ecological, engineering and economic considerations.

All facets of tailings disposal were considered in this review including tailings transport to the proposed outfall sites, outfall design, tailings behavior and dispersal patterns in the marine environment, and the ecological significance of each component.

Four outfall sites have been proposed by United States Borax & Chemical Corporation and Bechtel Civil & Minerals Inc.: one in Wilson Arm, one in Boca de Quadra central basin and two in Boca de Quadra inner basin. Upon extensive review of the available information, Rescan has selected two additional outfall locations for consideration: one in Wilson Arm and one in Boca de Quadra inner basin. ln the collective opinion of the Rescan Group, the new sites have less potential for causing ecological impacts than the previously proposed outfall locations in these basins. The following summary is based on discharge from the new sites to Wilson Arm and the inner basin of Boca de Quadra, and the previously proposed outfall site in the central basin of Boca de Quadra.

The marine ecologies of the three proposed receiving basins was compared to evaluate whether any ecological differences might dictate the preferred disposal site. A number of ecological indices (twenty) ranging from basin depth through primary, secondary and tertiary production were examined to providean indication of the relative biological productivity of the three basins. Previous assessments have suggested that Wilson Arm/Smeaton Bay is the most productive area and central Boca de Quadra the least, with the inner basin of Boca de Quadra being intermediate. This ranking of productivity was based on subjective assessments which identified one parameter, often salmon, as more important than another. While this might reflect economic or recreational values, it may not provide a realistic appraisal of the ecology of these fjords. Rescan believes a more comprehensive appraisal of the ecologies of these fjords is appropriate. Consequently, no biological parameters were tiweightedi as being more important than others in this review. In Rescan's opinion, the productivity evaluation presented here is an objective ecological comparison of the three basins to date. Using this approach, there is no statistically significant difference between the biological productivity of the Wilson Arm/Smeaton Bay system and Boca de Quadra central basin. The inner basin of Boca de Quadra has a slight, but statistically significant, lower productivity than either of the other basins. In a further analysis, Smeaton Bay and central Boca de Quadra were compared. These results did not indicate a biological basis for concluding that there is a difference between these two areas. Although these evaluations show some minor differences in ecological productivity, it is not considered sufficient in itself to form a basis for choosing a preferred option for submarine tailings disposal.

The tailings are not expected to be toxic to marine organisms. Although an initial bioassay conducted on a single pilot plant tailings sample indicated the tailings toxicity was detectable at the proposed dilution level in the outfall tank, the final reagent suite and respective addition quantities have not been finalized. It is expected that proper manipulation of these factors would eliminate the apparent tailings toxicity.

No significant trace metal boaccumulation or biomagnification is expected in the planktonic, pelagic or intertidal benthic organisms of the three basins considered. However, some metal bioaccumulation would occur in deep sedentary particle feeders inhabiting the tailings deposits. The diverse ecosystem food networks demonstrated in each basin suggests there are no significant biomagnification routes. There is no difference between the three basins in this context.

Another relevant factor that could dictate a preferred disposal option is the physical oceanography of the receiving basins. The major considerations are the general water circulation in the basins, and the magnitude and duration of bottom currents. By characterizing the general water circulation patterns, some indication of relative flushing regimes and direction of water mass movement is possible. Of primary concern is the potential for vertical advection of deep basin waters into the euphotic zone. The magnitude and duration of bottom currents in each basin also indicates the potential for redistribution and resuspension of deposited tailings.

Oceanographically, the three basins appear to have similar surface water circulation patterns while deep water movements are largely unique to each basin. Some redistribution of deposited tailings is expected in each basin; this would be accompanied by some resuspension at depth. Based on available data, theWilson Arm/Smeaton Bay system appears to have the most disturbed sedimentation regime of the three basins. This would suggest that this basin has the highest potential for resuspension of tailings materials. There are no indications from the data available for the three basins that resuspended tailings material would be circulated into the euphotic zone in any of the three basins if a properly designed and operated outfall were employed. This conclusion should be applied more cautiously to the Wilson Arm/Smeaton Bay system due to more limited oceanographic data.

Accepting that there is some uncertainty regarding potential fo vertical advections due to the limited oceanographic data and the unpredictability of long term changes in oceanographic characteristics, it is useful to consider the possible effects of vertical advections. Although deep water intrusions to surface waters have not been documented in any of the basins, it is suggested that if such events do occur, they would be short term and sporadic. Should any intrusion of deep, turbid waters into the euphotic zone occur, it would likely be during winter months when the pynocline is least developed. Since primary productivity would be lowest at this time, no major ecological impacts should be expected. With the onset of spring and the formation of a more pronounced pynocline, deep waters would be isolated from the surface. Since the spring phytoplankton bloom is not characteristically initiated until after the formation of a strong pynocline, surface water turbidity might, at worst, delay the spring bloom. Further, any suspended materials injected into the euphotic zone should settle rapidly. (Monitoring at the Kitsault Mine in BC shows that approximately 60 percent of the deep suspended material settled within 24 hours.) Impacts from any sporadic intrusions of deep waters into the euphotic zones in each basin are therefore not anticipated to cause significant ecological impacts. This is supported by monitoring at the Island Copper Mine in British Columbia where, despite significant localized increases in surface water turbidity during spring and summer (i.e., the most productive period) there has been no apparent effect on primary productivity.

It should be noted that the above consideration of impacts applies to deep water intrusions into the euphotic zone but not necessarily impacts arising from tailings spillage to surface waters from transport system failures. Should a major spill reach inlet waters, the resultant suspended solids loading in the euphotic zone would be orders of magnitude higher than loading from injection of deep turbid waters into the euphotc zone. As such, ecological impacts could develop in each basin if a major, uncontained spill occurred. It is therefore necessary that design considerations be given to providing emergency handling facilities.

The tailings flow and dispersal patterns from each of the proposed outfalls in the three basins would differ to some extent due to unique submarine topographical features. However, in general, tailings transport on the basin floors would be accomplished through a combination of steady state density flow and slumping. Deep water turbidity would be associated with tailings movement in each basin. There is no apparent basis for selecting a preferred disposal basin based on tailings movement patterns on the seafloor.

It therefore appears from the available data that there are no ecological, oceanographic or topographical factors unique to any basin which dictate outright the preferred disposal option. Thus, selection of a preferred disposal site depends on less obvious considerations. There are a number of these considerations, both positive and negative, for each basin. These are outlined below.

Wilson Arm/Smeaton Bay

A major issue concerning tailings disposal in Wilson Arm is the potential impact on salmon runs in the Wilson and Blossom Rivers. Tailings disposal should have minimal or no effect on returning adult salmon since they have probably ceased feeding before entering Wilson Arm/Smeaton Bay. Many runs of salmon have return migrations through naturally turbid estuaries and rivers (e.g., Fraser River). Juvenile salmon feeding in the Wilson-Blossom River estuary and along the inlet margins should not be affected by tailings since these juveniles are surface orientated during this rearing period. No major impacts are anticipated even if tailings were sporadically introduced into surface waters. Limited data on juvenile salmonids in Rupert Inlet, BC, where Island Copper Mine discharges tailings, do not indicate that mine-derived turbidity adversely affects salmonid growth rates. Thus, unless veryhigh surface water turbidity occurs over long time periods, impacts of submarine tailings disposal on salmon in Wilson Arm/Smeaton Bay are anticipated to be negligible.

Re-assessment of the expected volume necessary to contain the entire quantity of tailings discharged during the life of the mine has indicated that the Wilson Arm/Smeaton Bay system would readily accommodate the expected total volume of tailing solids. However, disposal of tailings into Wilson Arm would undoubtedly result in the transport of minor amounts of tailing solids into Behm Canal by advection of turbid deep waters over the sill. The introduction of minor quantities of tailings into the deep waters of Behm Canal is not seen as an important environmental issue by the authors of this review. The large volume and deep basin floor of Behm Canal, combined with the introduction of substantial amounts of glacially derived sediments to surface waters via the Chickamin River, suggest that ecological impacts from minor quantities of tailings introduced into the deep waters of Behm Canal would not be significant.

As mentioned above, the topography of the basin floor in Smeaton Bay and Wilson Arm appears considerably disturbed. This suggests natural sediment redistribution processes may exert a major influence on the basin floor topography. Oceanographic data indicate that these processes are only relevant during the summer deep water renewal events in Smeaton Bay. It is reasonable to expect that tailings deposits would be influenced to a similar degree. Although there is no evidence to suggest that these redistribution events would result in ecological impacts in surface waters, Rescan is reluctant to recommend the Wilson Arm/Smeaton Bay alternative as a priority site. This is primarily due to the limited data on bottom currents and oceanographic features in the system. Further investigations are necessary before this site could be recommended as most preferable.

Boca de Quadra - Central Basin

The central basin of Boca de Quadra is the argest of the three basins and would easily accommodate the entire projected tailings discharge volume over the life of the mine. The greater part of the central basin may also have the lowest resuspension potential of the three basins. Although significant tailings redistribution would occur in the deepest part of the basin adjacent to the Kite Island sill, quiescent conditions appear to predominate for most of the basin length (28 km).

An additional positive feature associated with the central basin is that it contains the largest volume of water and hence the greatest opportunity for turbidity cloud dilution. This would reduce the potential for ecological impacts in the unlikely event that deep waters were mixed into the euphotic zone.

Tailings transport to the outfall in the central basin is proposed by either a floating or near surface pressurized pipeline or via a tunnel to the discharge point. Due to the potential risks associated with pressurized tailings flow and the difficulty in providing adequate emergency handling facilities to mitigate pipeline failures, surface transport of tailings along the inlet margins is a questionable proposition from an environmental perspective. However, should tailings transport be by tunnel directly to the site, and adequate emergency handling facilities were feasible, direct tailings discharge to the central basin is a technically viable disposal alternative.

Boca de Quadra - Inner Basin

There are some positive aspects for discharging tailings to the inner basin of Boca de Quadra. This basin presently has a lower productivity than the other two basins. In addition, filling of the inner basin to sill height might have a beneficial effect on the ecological productivity of the area. By decreasing the depth, benthic productivity might be enhanced due to increased deposition and incorporation of organic detritus into the bottom sediments as a result of the closer proximity of the surface water source of carbon. The importance of this potential enhancement cannot be ssessed at this time.

There are three perceived disadvantages to discharging tailings to the inner basin of Boca de Quadra. These factors were communicated to Rescan through United States Borax & Chemical Corporation and reflect the main concerns of regulatory agencies and associated consultants. The following discussion addresses these concerns.

The first concern relates to possible turbidity complications unique to the inner basin. Present oceanographic data indicate the presence of a relatively coherent, isolated water mass at mid-depth in the inner basin during fall and winter. Although the presence of this layer might be viewed as a positive aspect since it would inhibit vertical mixing of turbid waters towards the surface, there is some concern that fine tailings material retained in this layer for extended periods of time may subsequently increase the dissolved metal loading in this water. Although the very low accessory sulphide content of the Quartz Hill ore would suggest such dissolution is not an important factor, the authors would recommend increasing the tailings discharge depth to 80 m to minimize entrainment of solids into this isolated layer. Increasing the discharge depth also would be beneficial in that turbidity from dispersal of tailings into the water column would be further removed from the euphotic zone, thus potentially reducing the probability of turbidity infringement on near-surface waters. In time, the 80 m depth would have to be reduced to 50 m to maintain adequate "head" to drive tailings into the central basin. Several years of monitoring data would be available prior to reducing the depth of discharge. That would insure a better understanding of the behavior of the turbidity plume and the resultant impact on the water column.

A second concern regarding disposal of tailings in the inner basin is that tailings would affect both the inner and central basins by the end of mining activity. The tailings material is anticipated to be relatively innocuous. Monitoring data from oher Pacific coast mines utilizing submarine tailings disposal show recolonization of disturbed benthic areas proceeds rapidly upon stabilization of the substrate. The disadvantage of altering both the inner and central basins of Boca de Quadra is therefore not considered a major environmental issue.

A third concern regarding tailings discharge to the inner basin relates to a probable change in oceanographic features as a result of filling the basin. Current meter data suggest that density intrusions into the bottom waters over the inner sill during typical summer months. These intrusions should diminish as the basin fills. There is some concern that by diminishing the intrusions, basin flushing would be seriously reduced. Once the inner basin was filled, the bottom depth and topography would be similar to that presently in Wilson Arm. There is no indication in Wilson Arm that deep water turbidity, apparently resulting from slump events off the Wilson/Blossom River delta, is vertically advected. While this comparison is not directly applicable, it does suggest that any alterations in water circulation patterns arising from filling of the inner basin would not be a major concern.

It is the collective opinion of the Rescan Group that the concerns regarding disposal to the inner basin outlined above should not cause significant detrimental ecological impacts in either the inner or central basins of Boca de Quadra. Assuming that it is feasible to construct adequate emergency handling facilities, tailings discharge to the inner basin of Boca de Quadra is also a viable alternative.

In conclusion, there are no major environmental factors that precludes the use of any of the three basins for submarine tailings disposal. Rescan is reluctant to recommend the Wilson Arm/Smeaton Bay disposal option as a priority site due to some information deficiencies; principally in oceanographic and physiographic data. Should further investigations confirm the trends indicated by the present data, the Wilson Arm/Smeaton Bay system dsposal option should be acceptable environmentally and very attractive from an economic perspective. (Considering the economic advantage of Wilson Arm/Smeaton Bay, U.S. Borax may wish to conduct more studies to define further the oceanographic conditions and the physiographic features of the area.) Both the inner and central basins of Boca de Quadra are considered equally viable as disposal options. Disposal into a more confined area such as the inner basin might be beneficial should unforseen significant ecological impacts begin to develop after the first few years of discharge. At such time, discharge could be halted limiting the impacts to a smaller area where mitigation would be more feasible. Based on the available data and considering the increased economic burden of direct discharge into the central basin, it would appear that the inner basin disposal scheme from the outfall site proposed in this review is the most realistic disposal option.

This booklet is the fourth in a series of reports describing the continuing evolution of the Quartz Hill Molybdenum Project in southeastern Alaska, from discovery of the ore body to eventual operation of the mine and production of molybdenum concentrate (MoS₂).

This edition deals with conceptual plans for the proposed molybdenum mine. It must be emphasized, however, that although the actual development plans for the Quartz Hill Molybdenum Project are preliminary and subject to change, the commitment to develop and operate the molybdenum mine is not.U.S. Borax and its affiliate Pacific Coast Molybdenum Company intend to be a responsible part of the future of Alaska.

The U.S. Environmental Protection Agency must determine whether unreasonable degradation of tbe marine environment is likely to occur before issuing an NPDES permit for discharge of effluent to the ocean. The evaluation must follow guidelines (Ocean Discharge Criteria) established by the agency. If the discharge is expected to unreasonably degrade the marine environment, the permit may not be issued. If insufficient information is available to make a determination, the permit may not be issued unless the available data indicate that no irreparable harm will occur during the time monitoring is conducted.

This Ocean Discharge Criteria Evaluation (ODCE) considers a proposed discharge of mill tailings to either Boca de Quadra or Smeaton Bay, two fjords in southeastern Alaska. The tailings will come from the Quartz Hill molybdenum mine in a non—wilderness area of the Misty Fjords National Monument. Thedischarge will last for approximately 55 years at an estimated maximum of 80,000t/d solids (dry weight), or a cumulative total of 0.84billion m³ solids.

A marine terminal wastewaster outfall will discharge to Smeaton Bay an average daily volume of 39,000 gal/d of secondary treated sewage effluent and treated equipment washdown water as well as an average volume of 0.205 mgd of stormwater runoff.

U.S. Borax's Quartz Hill Molybdenum Project in Southeast Alaska is of much interest and concern to all members of Congress because of the pending Alaska Lands Legislation. In answer to many questions about the project, we have prepared this booklet which outlines one concept for the development of Quartz Hill.

The proposed action is issuance of a special use permit to Pacific Coast Molybdenum Company to construct an access road and approval of a plan of operations to conduct bulk sampling activities at Quartz Hill under authority of the Alaska National Interest Lands Conservation Act (Public Law 96-487). The area lies within the boundaries of the Misty Fiords National Monument and is administered by the Forest Service, U.S. Department of Agriculture. Based on available information, Quartz Hill is one of the largest known molybdenum deposits in the world and could supply 18 percent of world molybdenum demand. Two alternative road routes and their supporting facilities are analyzed for impacts on water quality, fish, wildlife and their habitats, and National Monument and wilderness values. Alternatives using a helicopter for ore transport are also analyzed.

The proposed action is issuance of a special use permit to Pacific Coast Molybdenum Company to construct an access road and approval of a plan of operations to conduct bulk sampling activities at Quartz Hill under authority of the Alaska National Interest Lands Conservation Act (Public Law 96-487). The area lies within the boundaries of the Misty Fiords National Monument and is administered by the Forest Service, U.S. Department of Agriculture. Based on available information, Quartz Hill is one of the largest known molybdenum deposits in the world and could supply 18 percent of world molybdenum demand. Two alternative road routes and their supporting facilities are analyzed for impacts on water quality, fish, wildlife and their habitats, and National Monument and wilderness values. Alternatives using a helicopter for ore transport are also analyzed.

U.S. Borax and Chemical Corporation has proposed constructing and operating an 8O,OOO ton-per-day molybdenum mine and processing facility at the Quartz Hill Site, 45 miles east of Ketchikan, Alaska. The construction and operation of the proposed project would require issuance of special use permits and leases by the Department of Agriculture, Forest Service under the authority of the Alaska National Interest Lands Conservation Act (ANILCA), issuance of at least one Department of the Army permit by the U.S. Army Corps of Engineers under the authority of Section 10 of the Rivers and Harbors Act of 1899, and Section 404 of the Clean Water Act and issuance of National Pollutant Discharge Elimination System (NPDES) permits by the U.S., Environmental Protection Agency under the authority of the Clean Water Act. The mine development project would consist of an open pit mine, waste rock disposal areas, ore crushing and transport, a concentrator, tailings transport and disposal, employee housing and support facilities such as roads, water supply, wastewater treatment, and power supply. Nine alternative project concepts were investigated including the proposed project and the no-action alternative. The proposed project includes a mill at Tunnel Creek, marine tailings disposal in the inner basin of Boca de Quadra and workers living at single status housing at the project site and commuting during days off to Ketchikan. The other alternative concepts are:

1. No Action
2. Tunnel Creek Mill with Boca de Quadra Tailings Disposal and a Townsite at either Bakewell, Wilson I, or Wilson Ila
3. Tunnel Creek Mill with Wilson Arm Tailings Disposal and either a Townsite or Commute
4. Beaver Creek Mill with Boca de Quadra Tailings Disposal and either a Townsite or Commute
5. Beaver Creek Mill with Wilson Arm Tailings Disposal and either a Townsite or Commute
6. Beaver Creek Mill with on-Land Tailings Disposal and either a Townsite or Commute
7. North Meadow Mill with Boca de Quadra Tailings Disposal and either a Townsite, including the possibility of a Keta site, or Commute (the "Keta Alternative")
8. North Meadow Mill with On-Land Tailings Disposal and either a Townsite or Commute.

Several subalternatives were also investigated including, but not limited to, disposal of tailings to the inner basin versus the middle basin of Boca de Quadra, the immediate versus phased-in development of a townsite, alternate tailings tunnel alignments, and power supply from an on-site power plant versus a transmission line from BC Hydro. Impacts of each alternative were evaluated and potential mitigation measures were identified.

U.S. Borax & Chemical Corporation has proposed constructing and operating a nominal 80,000 ton-per-day molybdenum mine and processing facility at the Quartz Hill site, 45 miles east of Ketchikan, Alaska. The construction and operation of the proposed project would require issuance of special use permits and leases by the Department of Agriculture, Forest Service, under the authority of the Alaska National Interest Lands Conservation Act (ANILCA); issuance of at least one Department of the Army permit by the U.S. Army Corps of Engineers, under the authority of Section 10 of the Rivers and Harbors Act of 1899, and Section 404 of the Clean Water Act; and issuance of National Pollutant Discharge Elimination System (NPDES) permits by the U.S. Environmental Protection Agency under the authority of the Clean Water Act. The mine development project would consist of an open pit mine, waste rock disposal areas, ore crushing and transport, a concentrator, tailings transport and disposal, employee housing and support facilities such as roads, water supply, wastewater treatment and power supply. Nine alternative project concepts were investigated including the proposed project and the no action alternative. The proposed project includes a mill in Tunnel Creek, marine tailings disposal in Wilson Arm, and workers living in single status housing at the project site and commuting during days off to Ketchikan. The other alternative concepts are the following:

1. No Action
2. Tunnel Creek Mill with Boca de Quadra Tailings Disposal and either a Commute Option or a Townsite either at Bakewell Arm or at one of two sites near the mouth of the Wilson River.
3. Tunnel Creek Mill with Wilson Arm Tailings Disposal and a Townsite
4. Beaver Creek Mill with Boca de Quadra Tailings Disposal and either a Townsite or Commute
5. Beaver Creek Mill with Wilsn Arm Tailings Disposal and either a Townsite or Commute
6. Beaver Creek Mill with On-Land Tailings Disposal and either a Townsite or Commute
7. North Meadow Mill with Boca de Quadra Tailings Disposal and either a Townsite, including the possibility of a site near the mouth of the Keta River, or Commute (the "Keta Alternative")
8. North Meadow Mill with On-Land Tailings Disposal and either a Townsite or Commute.

Several subalternatives were also investigated including, but not limited to, disposal of tailings to the inner basin versus the middle basin of Boca de Quadra, the immediate versus phased-in development of a townsite, alternate tailings tunnel alignments, and alternate water supply sources. Impacts of each alternative were evaluated and mitigation measures were identified.

U.S. Borax Co. proposes to develop a significant molybdenum deposit at Quartz Hill in southeastern Alaska. The project is within the Misty Fjords National Monument, an area of considerable aesthetic and ecological resources managed by the U.S. Forest Service (Figure 1). The waste portion of the ore (tailings), comprising more than 99% of the total volume, would be disposed of in the vicinity of the mine.

The U.S. Forest Service, EPA and other Federal and State agencies have been preparing an Environmental Impact Statement (EIS) in accordance with the National Environmental Policy Act (NEPA), evaluating the potential environmental consequences of alternative mine development scenarios. Three alternatives have been considered for tailings disposal, one is an upland site and two are in nearby marine waters. During the initial phases of the NEPA process, the upland alternative for tailings disposal was eliminated. The remaining two alternatives allow disposal of tailings into either of two fjords: middle basin Boca de Quadra (Figure 2a) or Smeaton Bay/Wilson Arm (Figure 2b).

These two fjords are technically considered inland waters and are therefore not subject to the Ocean Discharge Criteria regulations (40 CFR §l25.l22) that apply to other marine discharges, in accordance with Section 403(c) of the Clean Water Act. EPA determined that, for the Quartz Hill project, the Ocean Discharge Criteria provide a useful framework for evaluating marine impacts and for determining permit conditions based on best professional judgment (BPJ) and applicable regulations. EPA's evaluation is presented in "A BP3 Evaluation Using the Ocean Discharge Criteria for Mill Tailings Disposal from the Proposed Quartz Hill Mine in SE Alaska" (EPA 1988a). This report is included as Appendix S of the U.S. Forest Service Revised Draft EIS (RDEIS). Due to the unprecedented nature of this project an limitations of the data presented in the RDEIS, an ecological risk assessment was developed as a tool to aid in the evaluation process.

The first step in the ecological risk assessment was to establish the important biological communities and their habitats. The communities which were considered as targets for environmental impacts were: salmon, herring, benthic invertebrates and zooplankton. The critical habitats for these organisms were observed to be the upper water column (above 100 meters) and the benthic sediments. The agents which were determined to be likely to cause harm are: 1) reagents, 2) settleable solids, 3) suspended sediments, and 4) metals (dissolved and particulate). Due to insufficient information regarding the type and toxicity of reagents proposed for the project, no conclusion was reached regarding the ecological risk due to exposure to these chemicals. The response of aquatic organisms when exposed to each of the remaining factors was predicted by:

• calculating the maximum loss of organisms due to avoidance or burial (settleable solids), and,
• comparison to ambient water quality standards (metals, specifically copper measured as total recoverable which includes dissolved and extractable copper).

The loss of benthic organisms due to deposition of tailings is approximately 4 times greater with the Smeaton Bay/Wilson Arm disposal option than with disposal in Boca de Quadra. This estimate is based on numbers of organisms reported in the RDEIS. If colonization is slow, this difference will be substantial.

A steady-state model, using the distribution of natural and man-made conditions, provided the basic framework for estimating the probability of environmental impact due to exposure to any of these agents. Water quality degradation (exceedence of the water quality criterion for copper measured as extractable portion of the suspended solids) is predicted to occur throughout the water column as a result of tailings discharge in either of the two fjords proposed as alternative disposl sites.

The critical habitat for pelagic organisms is above 100 meters in both fjords. The impacts of tailings disposal were evaluated with respect to the effect on this important habitat. As the project proceeds to the 55 year point, the concentration of suspended solids and concomitant copper will increase in the upper water column, presenting a higher probability of harm to pelagic organisms such as herring and salmon. The concentration of suspended solids and copper above 100 meters is higher for Smeaton Bay/Wilson Arm than for Boca de Quadra.

The resulting probability estimates for exceedence of the water quality criterion for copper have a number of features which are important for assessing the environmental impacts of tailings disposal in either of the fjords. First of all, these estimates show that concentrations of extractable copper concentrations will exceed water quality standards over a large part of whichever fjord is chosen for the disposal site. In Boca de Quadra, the average concentration of suspended solids and copper are higher than they are in Smeaton Bay/Wilson Arm, but the potential impact upon biota may be greater in Smeaton Bay/Wilson Arm due to the fact that the high concentrations occur higher in the water column where there is likely to be more biological activity.

The two fjords also respond differently to changes in geometry as the project evolves. There is little change in Boca de Quadra with time. In Smeaton Bay/Wilson Arm, there is a noticeable change in bottom geometry and specifically in the location of the discharge point as the project progresses. In Smeaton Bay/Wilson Arm, the discharge point is within 75-100 meters of the surface during the project's final stage. It is therefore, not surprising that the model predicts increasing Impacts in the upper water column as time progresses.

Uncertainty analysis was used to characterize the natural variability in the oceanographic characteristics of each fjord. The result of this characterization is a statement of certan differences in the hydrodynamics and hydrography of each fjord. These differences were used in the risk assessment to differentiate the type and magnitude of environmental impacts which may occur as a result of tailings disposal. It is clear that the aquatic ecosystem in Smeaton Bay/Wilson Arm is less likely able to accommodate the introduction of the tailings material than middle basin Boca de Quadra. Due to this natural variation in the two fjords, it may be assumed that the impacts (reagent toxicity, other metal toxicity) which are not addressed in this quantitative statement of risk will also increase the risk estimate for both fjords. Since measurements of the other agents were not completed, and expert knowledge regarding impacts is limited, the expected increases in risk estimates are not included in this analysis.

The U. S. Environmental Protection Agency must determine whether unreasonable degradation of tbe marine environment is likely to occur before issuing an NPDES permit for discharge of effluent to the ocean. The evaluation must follow guidelines (Ocean Discharge Criteria) established by the agency. If the discharge is expected to unreasonably degrade the marine environment, the permit may not be issued. If insufficient information is available to make a determination, the permit may not be issued unless the available data indicate that no irreparable harm will occur during the time monitoring is conducted.

This Ocean Discharge Criteria Evaluation (ODCE) considers a proposed discharge of mill tailings to either Boca de Quadra or Smeaton Bay, two fjords in southeastern Alaska. The tailings will come from the Quartz Hill molybdenum mine in a non—wilderness area of the Misty Fjords National Monument. Thedischarge will last for approximately 55 years at an estimated maximum of 80,000t/d, or a cumulative total of 1.18 billion m³ .

Data indicate that surface wind patterns in the Quartz Hill area are dominated by the local terrain. At all low elevation stations, wind directions tend to follow the contours of the significant local topographic features. Wind speeds are also greatly influenced by local terrain, however in more complex fashion. Local wind speeds result from a base velocity modified by terrain blockage and/or channeling. The results from 1982 revealed that surface wind speeds recorded in valleys ranged from approximately one-half to one-sixth those recorded at the exposed west ridge site. Precipitation measured at the exploration camp totalled 118.4 inches for 1982, as compared with 99.2 inches in 1981.

Ways of evaluating the community development in Boca de Quadra, a south-east Alaskan fjord, after a severe physical disturbance have been investigated using containers of defaunated natural sediment to simulate the benthic habitat at 15 m depth, near the fjord head. Development was found to be characterized by a progressive change in faunal composition from crustaceans to polychaetes, and increased numbers of taxa, density, and biomass. The diversity increased with increasing colonization periods for samples collected during the same season. The distribution of individuals among species did not show a trend with season or development. Patterns or abundance for Maldanidae, Nematoda, Lumbrineris luti, Leitoscoloplos pugettensis, Pholoe minuta, and Spionidae make these taxa promising indicators of the community maturity level. In order to assess the developmental characteristics of the community, it is concluded that it is very important to identify seasonal variations as these tend to mask the developmental trends.

The literature review draws for detail substantially on Canadian government reports dated as long ago as 1977 and 1980. It does not refer to the 1995 publicly available reviews of both sites (and other STD systems worldwide) in a refereed journal. Nor does it refer in any detail to the primary data analyses and reviews lodged by Island Copper Mine with the regulatory agency annually through to 1994, and scheduled to continue for two years post-closure.

The literature review misses the significance of the single most important factual point in these case histories. After 25 years of trend monitoring at Island Copper Mine to standards acceptable to the regulatory authorities in 1970, after a formal federal/provincial review 1978-80, and with annual reviews of monitoring reports by Federal and Provincial regulatory agencies, there have been no environmental effects, trends or concerns which have caused additional regulatory action.

The literature review frequently implies that unacceptable environmental effects could have been developing and could have been detected by contemporary monitoring and statistical analysis methods. It misses the point that these two permitted STD systems prevented substantial fishery and other resource losses inherent in the alternatives of beach, river or on-land disposal. The BPJ (Best Professional Judgement) of the Federal and Provincial regulators of the time worked, and sets the standard of marine resource protection to be achieved or surpassed elsewhere. The efforts, and success, of the regulatory agencies to this effect should be recognised.

Some example results of the 25 years of trend monitoring not detailed in the literature review follow.

• The crab fishery has maintained itself in the tailings-receiving fjords the crabs are not contaminated by the tailings, and data indicate a substantial supporting benthic feedstock for them.
• Available data calculating the relatively small amount of tailings escape from the predicted deposition area in the deepest part of the fjord trough have not been referenced and provided.
• The available data showing lack of effects of suspended and resuspended tailings on water column primary and secondary productivity have not been presented.
• There is no consideration of the substantial data now available on the rate of tailings deposition which generated no detectable environmental effects on the benthos.
• There have been substantial changes in the monitoring programme and its analysis arising from the formal and informal reviews. These have not been documented. Their significance has been dismissed quite summarily, presumably through not locating the information.

There are persistent exaggerations in the Literature Review of actual or postulated environmental effects, partly based on inappopriate use of words such as "large", and omission of words such as "small".

As concluded in the literature review, substantially more powerful environmental effects prediction and monitoring systems can be developed for the AJ Mine in 1996 than was possible in 1970, or even 1980. Monitoring to contemporary standards should permit earlier warning of trends of concern, if they should develop, than was possible in 1970. However, these developments need to be based on detailed use of the most recent primary reporting literature. Extensions and corrections to the Literature Review are needed for this to be achieved.

The Bureau of Mines devoted portions of the 1987-1988 field seasons to investigate the mineral aggregate industry in Juneau, Skagway, Haines, and Gustavus, Alaska, as part of the Juneau Mining District study. Statistics compiled for current suppliers include location, activity, reserve estimates, expected mine life, and types of commodities available. Each population center, except for Gustavus, is well endowed with suitable mineral aggregate to last at least 20 years.

The Bureau of Mines quantified the mineral aggregate resource in many large potential Sites within each area. Sampling, engineering and soil-index testing, site descriptions, deposit dimensions, and gold recovery information is described. Refraction seismic studies performed at three localities revealed gravel thicknesses in excess of 40 to 80 feet.

In the Juneau area, the Herbert/Eagle Rivers outwash area, East Fork Lace River, Antler/Gilkey Rivers, and Grizzly Bar (Taku Inlet) individually contain in excess of 60 million yd3 of excellent quality aggregate with minor accessory gold credits, Haines is also well endowed with aggregate resources; large, quality deposits occur along and at the confluences of the Chilkat, Katzehin, Klehini, Tsirku, and Kicking Horse Rivers. Large deposits of granitic aggregate exist in the Skagway River and East Fork Skagway River.

This environmental impact statement (EIS) discusses a proposal for hard mineral leasing in the Norton Sound Lease Sale Area, analyzes its potential effects on the environment, describes alternatives to the proposal, presents major issues determined through the scoping process and through staff analyses, and describes potential mitigating measures.

The proposal (Alternative I) consists of 40 blocks (approximately 72,148 hectares) in Norton Sound that range from about 5 to 22 kilometers offshore. Alternative II (No Sale) would cancel the proposed lease sale, tentatively scheduled for July 1989. Alternative III (Delay the Sale) would delay the proposed lease sale for a period of 3 years. Alternative IV (Eastern Deferral Alternative) would defer leasing on 15 blocks southeast of Safety Sound. Alternative V (Western Deferral Alternative) would defer leasing on 25 blocks located south of Nome. After a thorough review, the Secretary of the Interior will decide which alternative or combination of alternatives will be included in the Notice of Sale.

The potential effects of this proposal are based in part on the assumptions that gold (1) presently is the only marketable product that economically can be recovered from mining the offshore placer deposits in the proposed lease sale area and (2) recovery for the mean case is estimated to be 530,000 troy ounces.

The scenario used to assess the potential effects that placer mining may have on the environment describes possible activities and the timing of events. Exploration activities are predicted to begin in 1990 and continue through 2006; the initial exploration phase is estimated to occur between 1990 and 1992. Placer mining is predicted to begin in 1993 and continue through 2006. It is assumed that the placer deposits would be mined from single dredge containing an onboard processing plant to concentrate the recovered gold particles; beneficiation of the ore would be based on gravity concentration techniques. Offshore support activities are expected to include support vessels for anchor handling and dredge movement and helicopters for crew changes and transporting emergency supplies.

Table S-1 summarizes the possible effects that could occur as a result of the leasing proposal (Alternative I), the cumulative case, and with stipulation No. 1 in place. (Table S-2 explains the definitions used for assessing the potential effects of the leasing proposal). The analyses supporting the conclusions in Table S-1 assume that all laws, regulations, and orders are part of the leasing proposal; however, this does not include rules for leasing and operations of minerals other than oil, gas, and sulphur which are in preparation. If the potential mitigating measures described in Section II.D of the EIS were adopted, some of the effects described in the EIS would be reduced. (The effectiveness of the potential mitigating measures is discussed in Sec. II.D of the EIS.)

This EIS is not intended, nor should it be used, as a local planning document by potentially affected communities. The facility locations and transportation scenarios described in this EIS represent assumptions that were made as a basis for identifying characteristic activities and any resulting environmental effects. These assumptions do not represent a Minerals Management Service recommendation, preference, or endorsement of any facility, site, or development plan. Local control of events may be exercised through planning, zoning, land ownership, and applicable State and local laws and regulations.

Marine disposal of mill tailings has been practiced world-wide for over a century. However, only recently have the environmental effects of marine disposal been systematically studied. Some early attempts at marine disposal of tailings resulted in adverse impacts to marine life. However, recent advances in tailings disposal methods have included the introduction of engineered submarine tailings discharge systems, advanced environmental assessment and monitoring methods, and oceanographic modeling systems. Successful submarine tailings disposal (STD) has occurred at several mines.

The U.S. Bureau of Mines (BOM) has undertaken studies of the disposal of mining and milling wastes in the marine environment. The BOM Alaska Field Operations Center, Juneau, initiated a review of the technology, regulations, and economic aspects of STD. The review illuminated the need for organization of literature on the subject, therefore the Bureau compiled this extensive bibliography on marine disposal of mill tailings. The bibliography presented here contains 1483 references and is also available through diskette in the WordPerfect format. A review of the references indicates that literature on submarine disposal inadequately covers the subject. The majority of the references listed only peripherally relate to the subject. Published literature on the engineering and environmental aspects of STD is severely limited.

This Bureau of Mines publication presents a summary of mining activity in Alaska, as well as institutional and infrastructural factors affecting mineral deveopment in Alaska. Salient information on 67 significant mineral deposits in the State of Alaska is presented in abstract form. The deposits covered are those whose principal commodity is 1 of 20 commodities that appear to have commercial production potential within the State. Many of the deposits described are properties evaluated under the Bureau's Minerals Availability Program (MAP); additional deposits are included for more complete coverage. The appendix provides reference information on 214 additional significant mineral deposits.

Alaska, with about 74% of the U.S. continental shelf, is largely unexplored for placers in its vast shallow marine waters. Nevertheless there are numerous occurrences of marine minerals including gold, platinum, and cassiterite. Offshore dredging has recently begun in the Nome area. State and Federal agencies are preparing additional acreage for leasing.

This report reviews the regulatory environment as it pertains to tailings management and disposal from mining operations, excluding coal and placer gold operations, in the state of Alaska. It is based on the EPA's staff position on an effective program to regulate mining wastes as presented in the May, 1990 Strawman II document. The unique conditions which occur in parts of the state, including a fragile environment, high seismicity and permafrost, are identified. The special waste management practices which are necessitated by these conditions are delineated. The report provides a detailed outline of the current technologies that are suitable for designing, constructing, operating and closing a tailings disposal facility to meet environmental protection objectives. Cost implications to the milling industry of potential regulatory actions, such as the degree of groundwater protection are examined.

This report reviews the regulatory environment as it pertains to waste rock management and disposal from rning operations, excluding coal and placer gold operations, in the state of Alaska. It is based on the EPA's staff position on an effective program to regulate mining waste as presented in the May, 1990 Strawman II document. The unique conditions which occur in parts of the state, including a fragile environment, high seismicity and permafrost, are identified. The special waste management practices which are necessitated by these conditions are delineated. The report provides a detailed outline of the current technologies that are suitable for designing, constructing, operating and closing a waste rock facility to meet environmental protection objectives. Cost implications to the mining industry of potential regulatory actions, such as the degree of groundwater protection, are examined.

Special Report 33, Alaska's Mineral Industry-1983, is the third annual report produced jointly by the Department of Commerce and Economic Development, Office of Mineral Development, and the Department of Natural Resources, Division of Geological and Geophysical Surveys, detailing the activities of the mineral industry in Alaska during 1983. A prime objective is to provide both private sector and government agendas with reliable, current information concerning an industry which is expected to grow substantially in importance in the years ahead. The report is dependent on the cooperation of companies and individuals that supplied basic information.

The value of the mineral industry to the state's economy grew in 1983 to a gross worth of $294.3 million - a rise of 4% over 1982. The gain was due to continued growth of demand for sand, gravel and stone. This more than offset substantial declines in exploration and mine development activity.

A sustained world wide economic recovery will directly benefit the mining industry in Alaska. Major Pacific Rim markets are increasingly seen as vitally important for Alaska's minerals, however, participation in that marketplace continues to be constrained by the lack of infrastructure necessary to access and transport high bulk products such as coal and base metal concentrates from mine site to ship. Overcoming this limitation will take time and commitment by both public and private sectors of the economy.

Volume II of this two-part series on Submarine Tailings Disposal (STD) as a tailings management option for coastal and island mines contains descriptions of lesser known case histories.

The Misima gold mine (Papua New Guinea) and the Black Angel lead-zinc mine (Greenland) are described in some detail as the best documented cases. Atlas copper mine (The Philippines) is less fully described due to relative lack of documentation. The Misima and Atlas STD systems are working to their design criteria at Black Angel the system adopted did not prevent contamination for a number of reasons, which are now understood.

Two cases are described where STD is being developed. They are the Cayeli Bakir copper mine (Turkey), and the Toquepala and Cuajone mines (Peru). There is excellent documentation available for both cases.

Three case histories are described where tailings have reached the sea either through beach or river discharge. In one case the STD option has been explored (Marcopper Mine, The Philippines) In the others we explore in hindsight whether STD might have been a viable alternative using the Screening Criteria that this Volume develops - see below. The mines are Bougainville Copper Mine in Papua New Guinea, and Jordan River Mine (Canada). There is potential for STD at all three sites.

Finally, the Volume presents Screening Criteria for appraising STD, based on the experience in design, operation and environmental impact reviewed in the case histories.

This chapter considers the subtidal benthos of the Gulf of Alaska shelf, the Gulf's embayments, and its fjords. It presents a brief historical review of both fisheries and non-fisheries work, examines benthic data in order to assess both infaunal and epifaunal species-distribution patterns and biomass, discusses those environmental variables that are responsible for community composition, and briefly considers trophic groups and the feeding interactions between invertebrates and fishes. Benthic production estimates for the shelf of the northeast Gulf and for lower Cook Inlet are also calculated. The mean macrofaunal production for the northeast Gulf of Alaska (NEGOA) is estimated at 4.5 g C/m2y, with total benthic (microflora, meiofauna, and macrofauna) production estimated at 13.7 g C/m2y. Infaunal production estimates for lower Cook Inlet vary between 2.5 and 10 g C/m2y. The chapter also covers the relationships between the physiographic and the oceanographic features of the Gulf as well as those carbon-concentrating mechanisms that lead to benthic enrichment.

A review and synthesis of literature pertaining to biological consequences of submarine mine-tailings disposal (STD) was conducted. STD can result in massive sea floor sediment deposition. STD may also increase suspended sediment, trace metals and residual milling reagents in receiving waters. These perturbations, which are highly site dependent, invariably smother benthic organisms, and could potentially affect or alter fish, plankton, and benthos through acute and chronic toxicity, bioaccumulation, behavioral changes, smothering, derived secondary effects, and habitat alteration.

Much of the available information concerning STD is unpublished and limited to a restricted number of sites. From this information and related research, it appears that benthic smothering is the only major consequence of a properly designed STD system. There have been cases of metal bioaccumulation due to inadequate preliminary evaluation. Also, shallow water habitat alteration has resulted from STD. Reductions in biological production are likely due to benthic smothering. The rate of ecological recovery after termination of an STD operation varies and is difficult to assess.

The consequences of STD are site specific. Additional research is needed concerning possible consequences of milling reagents and the broad implications of benthic smothering. Also, methodologies are needed to allow better prediction of benthic recolonization and ecological implications of metal bioaccumulation.

Waste from coastal, metal mining operations may be disposed of in the ocean. Studies were conducted using tailings and wastewater (effluent) from a proposed gold mine that is located near Juneau, Alaska, USA. The ability of invertebrates to colonize tailings after obliteration by submarine tailings disposal (STD) was assessed through a field experiment. Trays of tailings and reference sediment were placed on the sea floor and retrieved over a 22 month period. The taxonomic composition. abundance, and biomass of invertebrates that colonized tailings and reference sediment were similar. Therefore, recolonization of invertebrates after obliteration by STD should not be inhibited by the presence of these tailings as a bottom substrate. In a laboratory study, the toxicity of effluent from the milling process was compared for early life stage fish and crustaceans. Common reference species and species that are indigenous to southern Alaska were exposed to effluent. The relationship between effluent concentration and organism response was established for immobilization paralysis and death. For each response, the sensitivity of the reference species bracketed that of the indigenous species. An overall ranking of species sensitivity could not be made because it depended on the response that was compared. The source of effluent toxicity was determined for one of the reference species, a crustacean. A simulated effluent was created to duplicate the ionic composition of the actual effluent. Toxicity was compared in effluent, effluent with increased salinity, simulated effluent, and solutions with adjusted concentrations of ions. Calcium was in excess in the effluent, relative to seawater, and was isolated as the source of toxicity. Sodium deficiency in the effluent, relative to seawater, reduced calcium toxicity.

Recent studies of the natural shore communities of the Gulf of Alaska provide a descriptive foundation for future work on the primary factors that determine both geographical and local distribution and abundance patterns for algal and invertebrate populations. However, there is still a lack of experimental evaluations to determine the role that physical disturbances, gradients in physical regimes, and biological interactions play in determining these patterns.

Our analysis of both the biotic composition and the zoogeographic affinities of those invertebrates of the major phyla revealed no major biogeographical discontinuities between Yakutat and the eastern Aleutian Islands. However, we found that the intertidal flora and fauna of the western Aleutians (Amchitka and Shemya Islands) differed markedly from the flora and fauna of the eastern GuIf. The distribution of species among trophic levels was similar between these two regions, but the western Aleutians had more Asiatic and fewer North American species, and had a greater proportion of endemic species of Mollusca, Crustacea, and Echinodermata than were found in the eastern Gulf.

Physical disturbance was only of overriding importance in controlling community structure at three of the 29 study sites. Gradients in the regimes for salinity, turbidity, and exposure altered both the community composition and the relative abundances of intertidal species, such as Semibalanus balanoides and Balanus glandula, which have a tolerance for a broad range of values for these factors. Pisaster ochraceus and Evasterias troschelli do not appear to play key roles in the organization of intertidal communities in Alaska because Mytilus californianus is rare there and M. edulis is vulnerable to the actiities of other predators and perhaps to physical disturbance as well.

When most intertidal species are lifted even slightly above their upper vertical limits by land-level changes, they either die or emigrate. This supports the contention that the upper limits of most intertidal organisms are physiologically determined. The exceptions are Balanus glandula, Semibalanus cariosus, and Chthamalus dalli which can survive uplift of nearly 1 m above their upper limits. It normally takes at least three years for communities to redevelop to their former condition after an uplift.

The Juneau Office of the U.S Bureau of Mines has undertaken a study of the environmental permitting process for major mines in Alaska to identify the effects ecosystem management has had or could have on the permitting process. To date, ecosystem management affects major mine permitting in Alaska primarily through the NEPA environmental assessment process. In Alaska, only the Forest Service has instituted ecosystem management in an overt and organized manner, while other agencies are doing so less directly.

In recent Bureau of Mines publications, the mine permitting process has been described using case studies of several recently permitted mines in Alaska. The insights into the permitting process and the conclusions of these reports are reviewed and summarized. Several ecosystem management issues were identified in the case studies, including the need for: effective communication between agencies; standardization and coordination of NEPA environmental impact assessment and environmental monitoring programs among agencies, and assessment and selection of alternatives based on risks to ecosystems regardless of jurisdictional boundaries or environmental media-specific regulations. Ecosystem management could be used as a way to systematize, organize, standardize, and coordinate permitting and monitoring requirements and management perspectives among government agencies and project proponents.

The Bureau of Mines (BOM) has begun a project to increase the understanding of the relationships between ecosystem health and its functions, and minerals development. The BOM, Juneau Branch, Alaska Field Operations Center, is providing support for ecosystem based land-management decision-making and the development of ecosystem based regulations by documenting the effects of mining on ecosystems and demonstraung the tools used to assess and analyze those effects. This is done by reviewing the data available on ecosystems and the environment at a mining site, the Greens Creek Mine near Juneau, Alaska, and applying available Geographic Information System modeling tools to assess the impacts of the mine on components of the pristine ecosystem. Habitat Capability Models for wildlife indicator species are used in this examination. Wildlife indicator species are used as indicators of ecosystem health by the U.S. Forest Service and the Alaska Department of Fish and Game, who developed these models for southeast Alaska. Analysis techniques from the U.S. Fish and Wildlife Service's Habitat Evaluation Procedures (HEP) are also used in this report.

By applying available models and analytical techniques to the Greens Creek area, the benefits gained through mitigation of potential impacts become apparent. These or similar techniques are useful for cost/benefit analysis of mitigation altematives. Also apparent from this analysis is that the degree to which potential impacts are observable will depend upon the ecosystem scale considered. This demonstrates the importance of defining the ecosystem and scale before performing impact and cost/benefit analysis. The watershed scale is found to be useful for assessing impacts to ecosystem components at the Greens Creek Mine. Much progress remains to be made in the modeling and prediction of impacts to ecosystems from mining activity.

This report details four case histories of Submarine Tailings Disposal (STD) from Canada and Alaska. STD involves relatively new technology to ensure that tailings are deposited below resuspension depth in chemically-unreactive Iow-oxygen deposits. Previous discharge systems to rivers and beaches were environmentally unsatisfactory as they did not achieve this environmental objective.

This report presents, for each case history, descriptions of the ore body and the milling process, the wastes produced the engineered tailings outfalls and data demonstrating the levels of environmental impact.

At Island Copper Mine, Canada, the STD system with both its positive and negative aspects is the best documented anywhere. A comprehensive monitoring program has been in place since 1970 prior to operations which started in 1971. Monitoring is scheduled to continue through to closure, expected in 1996, and possibly afterwards. Essentially, STD can deposit tailings to the seabed of a fjord in a way that does not contaminate either the overlying water column or the seabed and does allow local commercial fisheries (salmon and crabs) to continue. Where active tailings deposition and localized resuspension smothers benthos and causes turbidity there is no indication of impact on primary biological production, and natural recolonization restores a productive ecosystem within one to two years.

The other case studies include the Kitsault molybdenum mine, near the Canadian -Alaskan border, the WestGold marine placer dredging operation near Nome Alaska, and the proposed Quartz Hill molybdenum mine near Ketchikan.

The Bureau of Mines investigated submarine tailings disposal (STD) as an alternative to on-land tailings disposal. This report evaluates coastal metal deposits in the United States that may be amenable to STD. A pre-feasibility economic analysis comparing the two methods for twenty deposits in Alaska was completed. Environmental aspects of the deposits and potential effects of STD on minerals availability were evaluated.

On average, Net Present Values (NPV) were 22.3% larger for STD than for on-land disposal, due to a 17.0% reduction in capital costs, a 1.6% increase in operating costs, and a 7.1% reduction in breakeven prices.

Although STD has substantial promise for Alaska, a policy change would have little effect on minerals availability. Only three projects could benefit from STD in the near term. These deposits with a Gross Metal Value of $9.75 billion would provide 1 835 jobs. Four deposits may benefit in the longer term. These four marginally economic projects with a Gross Metal Value of $19.5 billion would provide 1,180 jobs. Thirteen would not benefit, as STD alone didn't overcome other economic factors.

None of the deposits had oceanographic or environmental constraints preventing STD use. Bathymetry, nearshore slope, profile, threatened and endangered species, and fisheries were considered for this preliminary report.