Principles for Managing Contaminated Sediment Risk at ...

Callahan Mine Sediment Tier I Memo

DATE: June 22, 2009

SUBJECT: Callahan Mine Superfund Site, Tier 1 Sediment Considerations Memo

FROM: Ed Hathaway, Remedial Project Manager

ME/VT/CT Superfund Section

TO: Steve Ells (5204P)

INTRODUCTION The Callahan Mine Site Proposed Plan will include a sediment clean action that applies to an area that is approximately 10 acres and an estimated 80,000 cubic yards. This memo satisfies the requirements of EPA guidance: Principles for Managing Contaminated Sediment Risk at Hazardous Waste Sites, February 12, 2002 OSWER Directive 9285.6-08; Response to Regional Request Regarding Sediment Cleanup at May 2008 Superfund Division Directors Meeting, July 3, 2008 OSWER Directive 9200.1-90; and the Guidelines for the OSRTI Review of Consideration Memos on Tier I Sediment Sites dated March 1, 2004. BACKGROUND • The Callahan Mine Site is a former zinc/copper mine located approximately 1,000

feet east-southeast of Harborside Village in the Town of Brooksville, Hancock County, Maine.

• The major mining operations occurred from 1968-1972, although there were some limited mining activities from 1881 to 1887. Approximately 5 million tons of waste rock were excavated to access 800,000 tons of ore. The ore contained zinc, copper, lead, silver, cadmium and arsenic.

• EPA began the remedial investigation (RI) and feasibility study (FS) (collectively, RI/FS) in 2003 and completed some preliminary RI/FS activities from 2003-2005. In 2005, the State of Maine Department of Transportation (Maine DOT) took over the RI/FS pursuant to an Administrative Order between EPA and the State of Maine. The cleanup of the Site has been split into two Operable Units. The first Operable Unit (OU1) Remedial Investigation Report (RI) was completed in April 2009. The draft Feasibility Study (FS) was submitted to EPA on May 1, 2009. The Record of Decision (“ROD”) is expected to be completed in 2009. The second Operable Unit (OU2) will be completed after an evaluation of the risk reduction accomplished by the performance of the remedy for OU1. A ROD for OU2 is not anticipated for several years. Table 1.1-1 from the RI Report is attached to this memo and provides a summary of the site investigation program.

• The major site areas include: an 21-acre tailing impoundment; three waste rock piles covering about 27 acres and containing overburden rock and low grade ore; the former processing facility; the former ore storage area; the Goose Pond estuary and

of 16


associated wetlands; Goose Cove; and the Mine pit and associated shafts and adits, which are all under Goose Pond. The pit was 600 feet wide and 320 feet deep at the end of the mining activities. See Figure 1 for the location of the potential source areas evaluated in the RI.

• EPA has identified the current owner (Smith Cove Preservation Trust), the former owner/operator (Callahan Mining Corporation) and the State of Maine as potentially responsible parties (PRPs).

RISK ASSESSMENT SUMMARY The Human Health Risk Assessment identified current threats to human health because of the presence of PCBs in the site soil/waste material and mine waste containing lead and arsenic within several residential properties adjacent to the Site. The groundwater at the Site is considered GW-A, the default classification in Maine. The groundwater under the waste areas, while not currently being used as a water supply, would be unsuitable for consumption as a result of Site related contamination. Soft shell clams within the Goose Pond estuary contained levels of lead well above health based standards, but the human health risk assessment did not identify an unacceptable threat from clam tissue ingestion owing to an assumption that only a very low frequency of exposure (3-5 clam meals per year) would occur. Table ES-3 from the RI Report is attached to this memo and provides a summary of the human health risk assessment outcome. The Baseline Ecological Risk Assessment identified current threats to the environment. Tables ES-4 and ES-7 from the RI Report summarize the ecological risk assessment and are attached to this memo. Following the completion of the ecological risk assessment, a supplemental evaluation of the information was performed to better align the effect data with the areas of historical mine waste deposition. The basic conclusions are of the ecological risk assessment are listed below:

• Areas of the Site were shown to be acutely toxic to aquatic organisms. • Contaminants from the Site are accumulating in plant and animal tissue.

Although the data set was not sufficient for a statistical evaluation, the concentrations detected in biota are well above background and reference locations:

o Salt grass contained up to 79 times more copper, 15 times more lead, and 54 times more zinc than the reference “clean” locations.

o Crabs contained up to twice the copper and zinc and 10 times the lead as reference locations.

o Fish tissue contained up to 10 times the copper, 62 times the lead, and 4 times the zinc as reference locations.

o Clam tissue contained up to 57 times more lead than reference locations. • Benthic community studies revealed a low diversity for both the Site and reference

locations suggesting that the physical stress of the estuary environment limits the type of organisms that can exist in this area. There was no major difference between the Site and reference locations based on the benthic community studies. However, based on data collected as part of the clam tissue collection program, the Southern Goose Pond area appears to have fewer clams and those found were of smaller size

of 16


than the remaining areas of Goose Pond. This information suggests that some level of benthic impairment may be occurring.

• Adverse impacts are possible for insect feeding shore birds (Spotted Sandpiper), fish eating birds (Great Blue Heron), benthic organisms, and fish in certain areas of based on contaminants in the “hot spot” areas of the sediment and salt marsh at the Site.

• Adverse impacts are possible for predatory birds (Red Tailed Hawk), insectivorous birds (Robin), omnivorous mammals (mouse), and worm eating mammals (shrew) based on contaminants in the soil/waste of the source areas.

. ELEVEN SEDIMENT MANAGEMENT PRINCIPLES: Each of the even items identified for consideration is discussed below:

1. Control Sources Early The conceptual model for the Callahan Mine identified three source mechanisms for the contaminated sediments (the CSM Figure from the eco risk assessment is attached to this memo. CMS figures for the source areas are also attached):

• sediment contamination resulting from the tailing, waste rock, and water management activities during mine operation (1968-1972);

• physical transport of tailing and suspended fine material from existing waste piles; and

• geochemical precipitate from groundwater discharge into Goose Pond. Figure 2, attached to this memo, shows the areas where mine related waste was deposited during the operational period of the Callahan Mine. The primary source of contamination to Goose Pond and Goose Cove sediments is interpreted to be historical mine operations. Four of the five high concentration areas in Goose Pond also correspond to areas of mapped mine waste. The largest area, adjacent to the tailings impoundment and Waste Rock Pile 3, is an approximate 10-acre, 2,400-foot reach of southern Goose Pond extending from the southern site boundary northward past the tailings impoundment and Waste Rock Pile 3 that has mine waste deposits up to 3 feet thick. Based on historical information, the primary source of these deposits is overflow from the tailing impoundment – either through the decant pipe or via overflow ditches at the northwest and southwest corners. Overflow from the northwest corner was also a likely major source of salt marsh contamination. In addition, discharge of contaminated groundwater through seeps and weathering of waste rock via acid rock drainage, followed by surface water transport of suspended and dissolved material, likely contributed to sediment contamination. It is unlikely, however, that precipitation from groundwater discharge (i.e., seeps and submerged groundwater discharge) could have created the 3 foot thick deposits documented during the RI. Overflow from the tailings impoundment and groundwater/seep discharge continue today. At Waste Rock Pile 3, weathering of waste rock via acid rock drainage followed by groundwater/seep and surface water transport of suspended and dissolved material also appear to be historical and potentially ongoing contributors to the Goose Pond estuary contamination. The primary source of

of 16


contamination to Dyer Cove sediments is interpreted to be use of the cove as a settling pond to remove suspended solids from mine pit water after sedimentation of Goose Cove became a concern. In addition, contaminated surface water runoff during and after mine operations as well as the discharge of contaminated groundwater are interpreted as historical and ongoing contributors to Dyer Cove sediment contamination. The area of highest contaminant concentration in Goose Cove corresponds to an area of mapped mine waste thought to result from mine pit dewatering. The area targeted for cleanup is the largest area of sediment contamination, the mine waste hot spot in southern Goose Pond. The majority of the sediment contamination is believed to have arisen as a result of mining operations that allowed tailing to flow into and fill the salt marsh and estuary in this area. Additional material has filled this area as a result of the physical transport of tailing from the tailing impoundment and fine material from Waste Rock Pile #3. The mine operations have ceased and the cleanup plan for the Callahan Mine targets both of these sources for control. Waste Rock Pile #3 will be removed and placed in the former mine pit and the tailing impoundment will be stabilized and capped to prevent any future migration of tailing. The only remaining source of contamination will be the groundwater discharge into Goose Pond. The source control measures will also significantly reduce the flux of contaminated groundwater from Waste Rock Area #3 and the tailing impoundment. The source control activities will be implemented along with the sediment remediation. The implementation of the source control measures are expected to protect the area subject to the sediment remediation from re-contamination. 2. Involve the Community Early and Often EPA has provided substantial involvement for the community. A Technical Assistance Grant (TAG) was provided in 2003. The TAG advisors have reviewed the Site documents and participated in technical meetings. EPA also performed a reuse assessment for the Site in 2008 and a report was released in April 2009. EPA has also met with the community at least annually to provide an update of the Site investigations and results. EPA has also released public information fact sheets describing the investigation activities and results at least annually. A copy of the April 28, 2009 public meeting presentation is attached to this memo. A site information update was also released in April 2009. The Site is located on Cape Rosier, which is a peninsula that had limited road access. Geologists and individuals interested in historic mining visit the Site occasionally. Otherwise, the Site visitors are predominately local residents. The entire Town of Brooksville, which covers about 31 square miles and includes the Village of Harborside that is located adjacent to the Site only has 900 residents. The population increases in the summer due to the large number of seasonal homes. There are no known tribal or other special interests at the Site. The Site is currently used for recreational activities such as walking, hiking, rock collecting or canoeing/kayaking

of 16


in Goose Pond. The largest waste pile rises above the surrounding area and is a popular vista for locals. The human health risk assessment evaluated current recreation use of the Site along with future residential use. The remedy targets the human health risks associated with PCBs and lead in soil and future groundwater use. The sediment cleanup level is driven by the ecological threat, but is also protective of human receptors. A property ownership figure and site area figure are attached to this memo to provide a better understanding of the site setting. The major concerns for the community have been: windfall use by the current owner after cleanup; local disturbance (truck traffic, noise) during cleanup; cost of cleanup to State of Maine (PRP); and perception that the Site is not a significant threat to people or the environment. EPA held meetings in May and July of 2008 to obtain local resident and other stakeholder input regarding the future use of the Site. The general consensus was that they preferred the Site remain accessible for passive recreation (hiking, scenic views from top of piles) with a split between those that favor cleanup and those that prefer it be left as is. The Site owner is a non-profit whose stated purpose is to preserve the property to protect the natural resources of the area. The Site abuts the Holbrook Island Sanctuary, which is a State of Maine park. The community response to the Proposed Cleanup will likely be mixed. The most significant issue is likely to be the financial impact to the State of Maine. Because the State of Maine is a PRP, the local view the cleanup as having a potential impact on their tax rates and level of municipal services. EPA has received input from several locals who are strong advocates for a cleanup, particularly the sediment cleanup in Goose Cove. Ironically, the sediments in Goose Cove may not be a primary focus of the cleanup as there is a low risk from this contamination. EPA has identified the Goose Cove location as a possible mitigation location that would allow the restoration of that area as part of the cleanup. There will be many locals concerned about truck traffic and other disturbance. There is local concern that the PCB contamination remains accessible to Site visitors allowing continued exposure to occur. To address community concerns, EPA has worked with the PRP consultant to identify a cleanup approach that will minimize the need for off-site truck traffic. All of the sediments that are excavated will be placed in the former mine pit, which is submerged. The waste rock that must be relocated will also be placed in the pit. The only material that will be shipped off-site will be the PCB contaminated soils. The tailing impoundment will be capped using a geomembrane and stone obtained from an on-site source, which will greatly reduce the need for off-site material. There is also a large (200,000 cubic yard) stockpile of clean sediments that were removed by the mining company from the mine pit that can be used for site restoration activities. The resource value of Goose Pond is predominately as an ecological resource. There is some use of Goose Pond for canoe and kayak recreation but Goose Pond is very shallow in most areas and is not suitable as a significant boating resource. Goose Cove has several homes along its shore. There substantial use for boating and one lobsterman uses a dock for storing pots. There are several boats in Goose Cove

of 16


during the summer. A major local concern is the loss of draft due to the mine waste in the bottom of Goose Cove. A cleanup that does not address Goose Cove would be viewed with less satisfaction by many locals. The Site itself sits in a low density residential/woodland coastal area. The properties abutting the Site on three sides are woodland. The opposite shore of Goose Pond is the Holbrook Island Sanctuary. There is a small residential area at the north access road. 3. Coordinate with States, Local Governments, Tribes, and Natural Resource

Trustees There have not been any tribal resources identified at the Site nor has there been any suggestion of tribal interest. EPA has worked closely with the State of Maine as both the support agency (Maine DEP) and the PRP (Maine DOT). There has been a good working relationship throughout the process. The performance of the RI/FS by the State of Maine has provided the State with a detailed understanding of the remedy. The State of Maine’s primary concern is what share of the cleanup EPA will assign to the State. State acceptance of the cleanup will depend largely upon that outcome. EPA recently notified the State of Maine that their share of a fund lead cleanup would be the standard 10% of the remedial action and the performance of operation and maintenance. The Maine DEP is supportive of the proposed plan. EPA has worked with the local officials by attending meetings, issuing fact sheets, and keeping the officials informed of site activities and results. The local officials are also concerned about the impacts on Town resources (roads), the state cost share, and do not see the site cleanup as a high priority. The Federal Natural Resource Trustees (NOAA and USFWS) have been very involved in the Site. They have reviewed all of the RI/FS documents, participated in site technical meetings, and visited the site on several occasions. The major resources of concern are the coastal fish and bird species along with the estuary habitat. They are both highly supportive of the cleanup approach. Develop and Refine a Conceptual Model that Considers Sediment Stability A Conceptual Site Model has been developed as part of the RI/FS. The CSM has been refined after each field effort, as needed. The overall contaminant CSM for the Site is fairly simple. The ecological risk assessment CSM is included on an attachment. From a contaminant perspective, the Callahan Mine is the only source of the contamination. The upstream area of Marsh Creek, which flows into Goose Pond, is clean. The marine areas in the vicinity of Goose Cove are also clean. The contamination is very well defined in extent. The contamination at the Site is a result of the former mining operations and ongoing releases from the mine waste areas. The major site-wide contaminants are copper, lead, and zinc. There is a small area where PCBs were detected. This is adjacent to several of the former buildings. The site

of 16


soil/waste also contains arsenic and lead above levels suitable for future residential use. Arsenic, cadmium, copper, manganese, and zinc are also found in groundwater. The source of the arsenic, cadmium, copper, lead, and zinc is the sulfide ore body that was excavated and processed at the Site. The CSM for transport and extent identifies the former mining operations as the primary mechanism that explains the presence of contamination at most locations. The sediment areas of concern were either used as settling basins, received tailing overflow, or were at the terminus of a discharge pipe. Ongoing physical transport from the tailing impoundment and Waste Rock Pile #3 is the next source of contamination. Groundwater leaching and precipitation in the pond is considered a relatively minor mechanism. Groundwater has been impacted by very localized leaching of the ore by infiltration. The physical characteristics of the sediment at the Site differ depending on location and the Site history. A majority of Goose Pond, including Middle Goose Pond, Dyer Cove, and South Goose Pond, contain soft sediments consisting of silt and organic clays. Discrete areas within Goose Cove, Dyer Cove, South Goose Pond, and the Irregularly Flooded area contain interpreted mine related wastes. These sediments consist of a light gray to gray talcose-type materials and are very soft. Water and sediment generated by pit operations were discharged to Goose Cove. Due to sediment accumulation in Goose Cove this practice was ceased early in mine operations. As a result, water and sediment generated by pit operations were pumped to a settling pond constructed in Dyer Cove. Mine-related wastes profiled in South Goose extend up to 3 feet in depth and are the result of the area having been used as a settling pond for sediment laden water decanted from the Tailing Pile during mining operations. Conversely, North Goose Pond and Goose Cove were found to have a hard bottom. Till may be exposed in this higher energy environment just south of the Goose Falls dam. At the base of Stink Cove, adjacent to the Former Pit, an area of hard bottom was also observed. This is likely a result of a documented sediment slope failure in Stink Cove. During the failure, approximately 10 feet of sediment slid into the Former Pit. The slope failure most likely exposed till deposits. Bioturbation of sediments is an active process at the Site. South Goose Pond, the irregularly flooded area of Goose Pond, and Dyer Cove are very shallow water environments. Water is typically less than three feet deep in most areas. The bottom surface consists of organic silt and muck that is easily stirred up. A thin veneer of organic muck (less than 1 to 3 inches) covers areas of mine-related talcose sediment in South Goose Pond and the irregularly flooded areas. These sediments are stirred up by foraging wildlife (herons and foraging ducks and geese). Clams and sand worms burrow into the sediment and mine waste materials, mixing deeper sediments and mine related waste with shallower sediments. Wind and wave action within these shallow water areas stirs up the fine-grained sediment and muck that forms the bottom and re-suspends sediment throughout the water column. South Goose Pond and the irregularly flooded area have been observed to be turbid on windy days. Through this process crystalline minerals that may have been deposited during mining operations or a result of transport with surface water runoff are likely being recycled to the top of the sediment column.

of 16


A sediment transport model was developed as part of the RI. The model looked at multiple storm events and tidal conditions. It confirmed that Goose Pond is a relatively stable setting with minimal export of material. The contamination is all located on the inland side of the former mine pit which acts as a sediment trap. A bedrock high at the outlet of Goose Pond also restricts the tidal flow and dampens the tidal range. Even though scour is a greater concern in Goose Cove, the area containing the contaminated sediments is within the lower energy, more stable, portion of the cove. Goose Pond is a low-energy environment, and, based on hydrodynamic modeling, mechanical suspension of shallow sediments by wave action and currents and longitudinal transport is expected to be minimal. Goose Cove is a higher energy environment, but potential for suspension of shallow sediments by wave action and currents and longitudinal transport, while greater than in Goose Pond, remains low. Sediment re-suspension by watercraft is more likely in Goose Cove than in Goose Pond. Estimated sediment accumulation rates in Goose Pond and Goose Cove are low (0.5 to 1 mm/year) and burying of contaminated sediment by accretion of uncontaminated sediment to the 6 to 12 inch depth needed to protect biological receptors could take hundreds of years. Vertical mixing of contaminated sediment with accreting sediment through bioturbation would be expected to keep surface contamination concentration high. Summary of Sediment modeling: Between August 24, and October 29, 2006, Woods Hole Group (WHG) collected hydrodynamic observations in the Goose Pond estuary to provide a general understanding of the hydrodynamic characteristics of the system, but also to provide the appropriate data for utilization in the development of a hydrodynamic model (WHG, 2007). Depth varying current velocities, water surface elevation, salinity, temperature, and turbidity were observed at three monitoring sites throughout the estuary. In addition, a brief bathymetric survey and a conductivity, temperature, and depth survey were collected to further quantify the hydrodynamics of the system. The Hydrodynamic Observations Report was included in Appendix O of the RI report. A summary of the data observations includes the following:

• Goose Falls produces a significant tidal dampening. Approximately 75 to 80 percent of the tidal amplitude is reduced as the tide propagates from Penobscot Bay into Goose Pond and the upper reaches. • Tides in Goose Cove ranged from 8.49 feet to 13.55, Tides in Middle Goose Pond average 3.3 feet and tides in South Goose Pond average 3 feet. • Both Middle and South Goose Pond exhibit a tidal lag of about 1.7 hours behind high water and 4 hours behind low water when compared to Goose Cove. • South Goose Pond experiences wide fluxes in salinity. The salinity ranged from 1.15 ppt on the neap tides to 27.24 ppt on spring tides. • During the data collection period, the tides were well resolved and were the dominant hydrodynamic process throughout the system. Tidal constituents accounted for 99.8 percent of the signal outside Goose Falls, while 87 to 89 percent of the signal was resolved inside of the Goose Pond system. This may vary during a different season condition, for example during the spring freshet.

of 16


• The longer period tidal fluctuations (associated with the spring-neap tidal forcing) have a significant influence over the hydrodynamics within the upper reaches of the Goose Pond estuary. This longer term tidal “pumping” creates significant influence on the water surface elevations, salinity, and turbidity within the estuary. • During the conditions existing during the data collection period, the system was determined to be flood-dominant. In general, this would result in a system that tends to fill with sediment over time. • The spring-neap tidal forcing also significantly influenced current velocities. Current magnitude was approximately doubled in Goose Cove during the spring tide versus the neap tide, while magnitudes in South Goose Pond were three times as large during the spring tides (when compared to neap). • During neap conditions at South Goose Pond, flow was not influenced as strongly by the tide, resulting in more unidirectional downstream flow. During spring conditions the upstream reaches of South Goose Pond, were more impacted by tidal influences (water surface elevation, salinity, and currents). • The CTD survey indicated stratification at approximately 10 meters deep in the vicinity of the former mining pit that may influence density driven circulation and vertical mixing. The observations were taken during a flood tide to provide an initial assessment of potential vertical variations in salinity and temperature.

Following hydrodynamic observation data collection, Woods Hole Group developed a 3-D hydrodynamic model utilizing the Environmental Fluid Dynamics Code (EFDC) to simulate extreme rainfall event discharge and storm surge events. The simulated extreme rainfall discharge events revealed increased velocities at the former earthen dam and upstream into Marsh Creek (WHG, 2008a). The storm surge events had the greatest effect on velocities near Goose Falls, within both Goose Cove and Goose Pond, while rainfall events (combined with an ebb flow) had an influence on the regions near the former earthen dam.

An assessment of sediment transport potential was made using the results from the hydrodynamic model and the Shield’s critical stress criteria for the initiation of sediment mobility (modified for fine cohesive sediments where required). Results showed the Goose Pond Estuary was largely depositional under typical tidal and flow conditions. The report concluded that although there is a possible influx/outflux of sediments between Goose Pond and Goose Cove, the sediments likely to be mobilized from within the system would be in the vicinity of Goose Falls, and are not likely to be derived from the deeper portions of Goose Pond. Therefore, under typical conditions, material within Goose Pond would remain sequestered within the system. Simulations of extreme rain event discharge indicated the potential for erosion in the surrounding areas of Goose Falls, near the former earthen dam, and in Marsh Creek. As with the existing conditions, though, the report concluded that suspension of existing sediments from the deeper portions of Goose Pond is not likely during the high rain events. The mobilized material for Marsh Creek is likely transported into

of 16


the deeper portions of Goose Pond; however, once in the Pond, cannot be easily transported out into Goose Cove. When compared to the rainfall events, storm surge event simulations revealed an increase in the erosion potential in the paths of the hydraulic jet features formed during the flood and ebb conditions at Goose Falls. Simulations of the storm surge events did not significantly increase sediment transport potential near the former mine pit, or in the upstream portions of the estuary, including Marsh Creek. However, the areas surrounding Goose Falls experienced marked increases in potential for contaminated sediment transport to Penobscot Bay. Overall, the report concluded that the Goose Pond system is primarily depositional. The hydrodynamic and sediment transport modeling indicate that contaminated sediments currently residing in the Goose Pond estuary are likely to remain sequestered in Goose Pond, and not be transported into Penobscot Bay. Although some sediment movement is expected to occur in Marsh Creek during higher rainfall events, this material will only be mobilized within the Goose Pond system and deposited in the former mining pit. Sediment near Goose Falls, and seaward of the falls specifically, does have a greater potential for mobilization and movement into Penobscot Bay. The Hydrodynamic Characterization and Sediment Transport Potential report was included in Appendix O of the RI report. As a follow-up to the initial hydrodynamic modeling, Woods Hole Group used the 3-D hydrodynamic EFDC model to evaluate the following potential future scenarios under the extreme storm conditions (e.g., 100-year rainfall and 100-year storm surge).

• removal of anthropogenic and natural features at Goose Falls • complete erosion of the earthen dam in Marsh Creek • evaluation of the potential turnover of waters within the mine pit

Two scenarios were evaluated for removal of anthropogenic features at Goose Falls: 1) removal of dam and bridge abutments, and 2) removal of anthropogenic and natural features (i.e., removal of dam and bridge abutments, roadbed and land southwest of bridge, and the deepening of the channel to allow full tidal exchange. Both scenarios yielded similar results and showed little change in sediment transport potential in Goose Pond compared to existing conditions. The removal of the anthropogenic features at Goose Falls Dam would increase the potential for erosion of the sediments within Goose Cove and upstream of the former earthen dam. The sediments that exist in Goose Cove could be exposed and mobilized under these conditions. Complete erosion of the remaining earthen dam in Marsh Creek did not greatly affect the hydrodynamics of the system. The potential future scenario was simulated in a 100-year precipitation event and similar trends were seen in current velocities and

of 16


areas of potential erosion when compared to existing conditions. Therefore, the complete erosion of the earthen dam will not significantly impact the overall hydrodynamics or sediment transport within the system. The technical memorandum concluded that turnover of waters within the deep former mine pit is unlikely. Under normal (existing) conditions, the dense waters in the pit are confined, and mixing only occurs in the upper 10 meters of the water column. During the simulation of 100-year extreme storm conditions coupled with the removal of the restriction at Goose Falls (i.e., removal of dam remnants and bridge abutments and widening the channel to approximately 200 feet and deepening it to allow full tidal exchange), vertical mixing increased to the upper 40 meters, but did not entrain the bottom layers within the mine pit. This scenario was evaluated as a worst case, although unlikely, future condition. The hydrodynamic modeling technical memorandum is attached to the Feasibility Stud Report as Appendix A. The rate of sediment deposition in Goose Pond is estimated to be approximately 0.5 to 1 millimeters per year, and an estimated 300 to 600 years would be required to achieve background concentrations without bioturbation mixing at those rates. Sediment accumulation rates for Maine marshes were researched. Wood (1989) concluded that sediment accumulation rates in Maine salt marshes are highly variable. More specifically, fluvialtype marshes (e.g. similar to the upper reaches of Goose Pond) typically accumulate sediment at rates ranging between 1.1 and 5.9 millimeters/year (mm/yr). The average accumulation rate in fluvial marshes was calculated at 2.5 mm/yr. Also of note, 6 of 10 fluvial-type marshes showed that ice-rafted debris accounted for 0.2 to 6.7 percent of the sedimentation rate. At one extreme, a fluvial marsh location in Casco Bay, ice rafted debris accounted for 100 percent of the sedimentation rate. Based on the geomorphology of the Site, the upper reaches of Goose Pond near WRP-3 and the Tailings Pile may be areas where ice rafted debris is a transport mechanism. A previous lead isotope study (Boeckeler, 1996) on a sediment core at the Site and in Penobscot Bay near Holbrook Island was reviewed. For mine waste sediments collected from Goose Pond and Goose Cove the 206Pb/207Pb ratio ranged from approximately 1.158 to 1.177. The source of lead in sediments exhibiting this ratio is considered to be related to Callahan Mine. The Boeckeler study also compared 206Pb/207Pb from Goose Pond/Cove to an undisturbed sediment core collected in Casco Bay interpreted to be distal from point sources of lead. As such, the Casco Bay core was considered to represent a non-point regional background location. The ratio for 206Pb/207Pb indicative of background was estimated to be 1.20 or greater. There appears to be good correlation between the 206Pb/207Pb ratios indicative of mine waste (1.157 to 1.177) and high concentration of mine waste metals - copper, lead and zinc. Fluvial marsh sedimentation rates are shown for comparison. Calculated sedimentation rates were generally lower than published accumulation rates estimated for fluvial marsh environments in Maine.

of 16


4. Use an Iterative Approach in a Risk-Based Framework There have not been any previous actions and the remedy is intended to be implemented as part of a multi-year effort. The exact sequencing would be identified during design. It is likely that the major source areas will be addressed first. The remedy for OU 1 targets the areas where the most significant risk reduction can occur. The areas targeted for sediment cleanup contain very high concentrations of contaminants and also contain mine waste that should not be in the wetland or estuary. EPA has identified several areas of the Site for OU 2 to allow for a phased, targeted risk reduction approach. It is possible that many of the OU 2 areas may not require remediation if the OU 1 cleanup is successful. Assuming that funding is available, the design for OU1, including the sediment remediation could be completed by 2011. The major components of OU1 could be completed by 2014. OU2 data gathering would continue until one or two years following the completion of the OU1 construction activities to define a post-OU1 baseline. 5. Carefully Evaluate the Assumptions and Uncertainties Associated with Site

Characterization Data and Site Models The overall CSM for fate and transport was based on knowledge of the site operations and interpretation of the Site data. The human health risk assessment was based on standard risk assumptions. The areas of human health risk under the current land use scenario (recreational) are exposure to PCBs in the former Mine Operations Area and exposure to lead and arsenic in soil at three adjacent residences due to the presence of mine waste in the access road and their yards. Although the clams within Goose Pond contain very high levels (up to 43 mg/kg) of lead, no human health threat was identified because only a very low frequency of exposure was assumed. ATSDR has advised that people not be allowed to eat the clams. There is currently a State of Maine ban on harvesting shellfish in Goose Pond. The only risk basis for the sediment cleanup is the ecological threat. A standard multiple line of evidence approach was used for the Baseline Ecological Risk Assessment (BERA). Site specific data was collected and used whenever possible. The sediment toxicity testing and food chain modeling provide the strongest basis for action whereas the benthic community data and AVS/SEM data were more ambiguous. Sediment toxicity tests included a chronic 10-day survival and growth for L. plumulosus and 28-day survival and growth for N. arenaceodanta. The food chain modeling for terrestrial and semi-aquatic birds and mammals used modeled doses that were compared to toxicity reference values (TRVs) based on no-observable-adverse-effects-levels (NOAELs) and lowest-observable-adverse-effects levels (LOAELs). The food chain model was based on site specific factors to the extent possible. The tissue from site fish and benthic organisms was used in the development of the bioaccumulation factors. Direct ingestion of sediment was responsible for 80% of the risk to the Great Blue Heron and 30% of the risk to the Spotted Sandpiper. As a result, just the removal of the contaminated sediment should

of 16


accomplish a dramatic risk reduction. See previous section for information about sediment modeling and deposition rateds. 6. Select Site-specific, Project Specific, and Sediment-specific Risk Management

Approaches that will achieve Risk-based Goals The Proposed Plan includes the following Remedial Action Objectives for the sediments: • Prevent exposure of biota to sediment, including the sediment/soil in the salt

marsh, with concentrations of copper, lead, or zinc that may represent a threat to insectivorous and piscivorous birds, fish, and other aquatic organisms.

The Feasibility Study evaluated the full range of sediment remediation options as part of the screening and development of alternatives. Excavation/dredging was identified as the only viable option to address the sediments. The shallow nature of Goose Pond did not allow for in-situ capping or monitored natural recovery. A one foot cover would dramatically alter the site hydrology and is not likely to be stable. Sediment deposition rates would require 300 to 600 years for the accumulation of one foot of cover, assuming the Site hydrology would not scour the material to maintain tidal flow. Treatment options were not available for metal contamination. The inorganic contamination has been present in the estuary since 1972 and there is no basis to assume transformation of these constituents to a less toxic form. In situ capping would not be appropriate for the largest area of sediment contamination, the Southern Goose Pond, because the area is very shallow and used recreationally. A cover of any thickness would expose the sediments for extended periods during each low tide. A cap would also not be appropriate for Goose Cove since the local stakeholders are already concerned about the loss of draft for boats due to the mine waste. Excavation was the only practical approach to achieve cleanup goals and was carried into the detailed evaluation in the Feasibility Study. One major advantage for the cleanup is the presence of the former mine pit in the middle of Goose Pond. The pit has bedrock walls, is 300 feet deep, and can hold almost 2 million cubic yards of material. The sediments represent only about 10% of the available capacity. EPA requested the support of the USACE through the EPA HQ and the USACE confirmed that a dredging operation that excavated the sediments and pumped them directly into the pit was feasible. This dramatically reduces material handling costs as no dewatering or staging of the sediments would be necessary. The OU1 sediment cleanup at the Site as these were the only sediments identified in the risk assessments as a threat to ecological receptors. As discussed earlier, the sediment cleanup for the Callahan Mine is based on the results of the ecological risk assessment and remedial investigation. There area targeted for sediment remediation is a combination of the open water estuary sediments in Goose Pond and the adjacent salt marsh. This area extents over almost 20 acres and includes 80,000 cubic yards of contaminated sediment, which is about 60% of the area to be excavated. If Goose Cove were to be included in the

of 16


excavation program as part of the wetland restoration, then an additional 10,000 cubic yards would be removed and placed in the pit. 7. Ensure that Sediment Cleanup Levels are Clearly Tied to Risk Management

Goals The human health risk assessment was based on standard risk assumptions. The areas of human health risk under the current land use scenario (recreational) include the PCBs in the Mine Operations Area and three adjacent residences due to the presence of mine waste in the access road and their yards. The mine waste contains lead and arsenic above human health residential risk levels. Although the clams within Goose Pond contain very high levels (up to 43 mg/kg) of lead, no human health threat was identified because only a very low frequency of exposure was assumed. ATSDR has advised that people not be allowed to eat the clams. The only risk basis for the sediment cleanup is the ecological threat. A standard multiple line of evidence approach was used for the Baseline Ecological Risk Assessment (BERA). Site specific data was collected and used whenever possible. The sediment toxicity testing and food chain modeling (Gobas? List models used) provide the strongest basis for action whereas the benthic community data and AVS/SEM data were more ambiguous. The sediment PRGs are based on the sediment toxicity tests and food chain models. There were set at effects level risk numbers, which means that the Lowest Observed Effect Level (LOAEL) was used rather than the No Observed Effect Level (NOAEL). The copper (790 mg/kg) and lead (710 mg/kg) PRGs were based on the LOAEL for the Sand Piper. The zinc (5,100 mg/kg) PRG was based on survival results from the sediment toxicity testing. Tables showing assumptions for the Food Chain modeling are attached to this memo.

Ecological PRGs for Sediment and Wetlands Sediment Safe level for aquatic

biota and birds Copper 790 mg/kg Lead 710 mg/kg Zinc 5100 mg/kg

8. Maximize the Effectiveness of Institutional Controls and Recognize their

Limitations Institutional controls will be used to maintain the effectiveness of the cleanup by prevent future uses of the Site that could cause a release from the capped tailing

of 16


impoundment. Institutional controls would also prohibit future clam collection at the Site. Deed restriction would be used on the land portions of the Site to prevent activities that would disturb the cap or wetland areas. The State of Maine owns the bottom of the estuary. The State Superfund Contract and/or any settlement agreement that involves the State of Maine would have language to require restrictions on the future use of Goose Pond to prevent any disturbance of the material placed in the mine pit. 9. Design Remedies to Minimize Short-term Risks While Achieving Long-Term

Protection Explain that you are not in the design phase yet. Give schedule for PP, ROD, & RD The sediment cleanup would not have any societal or cultural impact as the area is currently closed for all harvesting and there is very little use of the aquatic resources in Goose Pond. The dredging actions would be designed to minimize any contaminant release. These measures will be detailed as part of the design. The disposal unit is the former mine pit. EPA requested the support of the USACE through the EPA HQ and the USACE confirmed that a dredging operation that excavated the sediments and pumped them directly into the pit was a very likely scenario (personal communication from site visit). This FS assumes the use of a hydraulic dredge that pumps dredged material directly to the mine pit through high-density polyethylene piping. This would eliminate the need for on-shore handling, dewatering, and the construction of an upland confined disposal facility. A drop tube would be used to lower the actual discharge point and reduce entrainment of material in the upper portion of the water column. Silt curtains would be placed around the mine pit to reduce potential for turbid water to migrate to other areas of Goose Pond. Proper selection and operation of dredge equipment will help minimize migration of suspended material from the dredge site. In addition, silt curtains will be used as appropriate to minimize migration of suspended material from the area being dredged. Dredged material will be placed below the mixing boundary in the mine pit to prevent long-term contamination of surface water in the remainder of Goose Pond. The available data indicate that the mine pit can hold up to 1,300,000 cubic yards of source material and dredged sediment without filling above the mixing boundary. This is more than adequate to hold the estimated 101,000 cubic yards of sediment and 347,000 cubic yards of source material and soil identified for disposal in the pit. The estimated volume for material that may be placed in the pit is 448,000 cubic yards, which would only fill the pit to an estimated depth of 120 feet below sea level. 10. Monitor During and After Sediment Remediation to Assess and Document

Remedy Effectiveness.

of 16


The RI provided a good baseline data set for the sediment cleanup. Sediment data will be collected during the cleanup and post-cleanup. Clam tissue and sediment toxicity will be among the measure of effectiveness as well as concentration. The remedial goal will be for the post cleanup UCL for the area to be below each of the PRGs. List References 1. MACTEC 2005. “Callahan Mining Superfund Site Draft Quality Assurance Project

Plan for Remedial Investigation/Feasibility Study”; Maine Department of Transportation; MACTEC; June 2005.

2. MACTEC 2005, Draft Project Work Plan, Callahan Mining Superfund Site, Brooksville, Maine, June 2005

3. MACTEC, 2005. Final Interim Work Plan No. 2 for Remedial Investigations at the Callahan Mine Site, Brooksville, Maine, June, 2005.

4. MACTEC, 2006, Draft Phase 1A Remedial Investigation Report, Callahan Mining Superfund Site, Brooksville, Maine April 2006.

5. MACTEC, 2006, Draft Baseline Ecological Risk Assessment, Callahan Mining Superfund Site, Brooksville, Maine June 2006.

6. MACTEC, 2006, Final Project Work Plan, Callahan Mining Superfund Site, Brooksville, Maine July 2006.

7. MACTEC, 2007, Phase 1B Work Plan, Callahan Mine Superfund Site, Brooskville, Maine; July, 2006.

8. MACTEC, 2007, Preliminary Geotechnical Evaluation Report, Callahan Mine Superfund Site, Tailings Impoundment Area, Brooksville, Maine February 2007.

9. MACTEC, 2007. Final Phase 1B Work Plan, Callahan Mine Superfund Site, Brooksville, Maine, July, 2007.

10. MACTEC, 2008 Geotechnical Evaluation Report, Callahan Mine Superfund Site, Brooksville, Maine December 2008.

11. MACTEC, 2009. Geotechnical Evaluation Report, Callahan Mine Superfund Site, Brooksville, Maine, January.

12. MACTEC, 2009. Final Remedial Investigation Report, Callahan Mine Superfund Site, Brooksville, Maine.

13. Woods Hole Group, 2007. Hydrodynamic Observations at the Former Callahan Mine Property, Brooksville, Maine: August 24 – October 29, 2006. For MACTEC, Inc., Portland, Maine. By Woods Hole Group, Inc., East Falmouth, Massachusetts.

14. Woods Hole Group, 2008. Hydrodynamic Characterization and Sediment Transport Potential at the Former Callahan Mine Property, Brooksville, Maine: Final Modeling Report, for MACTEC, Inc., Portland, Maine. By Woods Hole Group, Inc., East Falmouth, Massachusetts.

15. MACTEC, 2009, Draft Operable Unit 1 Feasibility Study. Callahan Mine Superfund Site, Brooksville, Maine

of 16

<Double-click here to enter title>

Belfast

Blue Hill

SITELOCATION

Figure ES-1Site Location Map

Remedial Investigation ReportCallahan Mine Superfund Site

Brooksville, MaineMACTEC, Inc.

¯ 0 4,0002,000

Feet

Docum

ent:

P:\P

roje

cts

\md

ot\C

alla

han

Min

e\6

.0G

IS\M

apD

ocu

men

ts\2

009

Executive

Sum

ma

ry\E

S_S

ite

Map

_8

x1

1.m

xd

PD

F:P

:\P

roje

cts

\mdo

t\C

alla

han

Min

e\6

.0G

IS\F

igu

res\2

009

Executive

Sum

ma

ry\F

igu

reE

S-1

.pdf

03

/24/2

009

1:4

3P

Mdb

wild

es

Prepared/Date: DBW 03/24/09 Checked/Date: SFC 03/24/09

MAINE 1:24,000 scale digital topographic mapobtained from Maine Office of GIS athttp://apollo.ogis.state.me.us/catalog

M:\Projects\Callahan Mine Site\Figure 5.3-l.dwg Thu, 20 Nov 2008 - l l:46am MRSTACEY

TRANSPORT PROCESSES: WASTE ROCK PILES AND ORE PAD 1. PRECIPITATION

2. SULFIDE OXIDATION. GENERATION OF ARD 2 ~ . NEUTRALIZATION OF ACIDITY

3. LEACHATE MIGRATION TO SEEPS

C_____3 4. LEACHATE PERCOLATION TO BEDROCK GROUNDWATER 5. GROUNDWATER MIXING, FLOW TOWARD DISCHARGE 6. GROUNDWATER DISCHARGE THROUGH SEDIMENT TO SURFACE WATER

0 b 7. LEACHATE/GROUNDWATER DISCHARGE TO SEEPS AND SURFACE WATER :a$ 0 b 9. DISCHARGE OF METALS TO SEDIMENT/ESTUARY COLUMN 8. SEEP DISCHARGE TO SALT MARSH FLOODPWN SOILS

0 b 0 10. WIND TRANSPORT

0 b 11. HALO METALS DEPOSITION 12. SURFACEWATER/EROSION AND SEDIMENTATION

STRESSED VEGETATION

METAL RETENTION MECHANISMS: A. FORMATION OF METAL OXIDES INSIDE WASTE ROCK PILES. B. PRECIPITATION MECHANISMS OPERATING WITHIN WASTEROCK PILE. C. MINERAL PRECIPITATES IN SURFACEWATERS/SEEP DISCHARGE AREAS. D. SORPTION/RETENTION OF METALS IN SALT MARSH SEDIMENTS. E. METALS IN GROUNDWATER; DISCHARGED TO AND RETAINED BY SEDIMENTS. F. METALS RETAINED IN "MINE WASTE" LAYER IN SEDIMENT. G. AREAS OF EROSION AND SEDIMENTATION IN GOOSE POND.

TRANSPORT PROCESSES: TAILINGS PILE 1. PRECIPITATION

2. SULFIDE OXIDATION, GENERATION OF ARD ABOVE WATERTABLE 2A. NEUTRALIZATION OF ACIDITY

3. SURFACE WATER RUN-OFF TO VERTICAL CAST IRON DRAIN PIPE 3A. SURFACE WATER RUN-OFF TO DRAINAGE DITCH

4. NO WRITE OXIDATION IN SATURATED TAILINGS 5. LEACHATE MIGRATION TO BEDROCK GROUNDWATER 6. LEACHATE MIGRATION TO SEEPS 7. BEDROCK GROUNDWATER FLOW AND DISCHARGE TO GOOSE POND 8. SEEP DISCHARGE TO MARSH FLOODPWN SOILS 9. DISCHARGE OF METALS TO SEDIMENT/ESTUARY WATER COLUMN 10. WlND TRANSPORT 1 I. HALO METALS DEPOSITION 12. SURFACE WATER/EROSION AND SEDIMENTATION 13. EROSION/SEDIMENTATION IN GOOSE POND

r DECANT DRAIN INLET

@ SPILLWAY DRAINAGE DITCH

TAILINGS -0

I ------o-g

I DECANT PIPE?

+ + + + + +

METAL RETENTION MECHANISMS:

I A. SEDIMENTATION IN DITCH BETWEEN TAILINGS IMPOUNDMENT AND SMALL BERM. B. SORPTION AND EXTENT OF METALS IN MARSH FLOOD PLAIN SOILS. C. METALS RETAINED IN "MINE WASTE" LAYER IN SEDIMENT.

I Pre~aredIDate: MRS 1 1/20/08

Figure 5.3-1 SlTE CONCEPTUAL MODEL

CALLAHAN MINE SUPERFUND SlTE BROOKSVILLE. MAINE

Project 361 2-06-2047.27


-1 0

-10

-10

-10

-20

Legend

Dyer Cove Perimeter

Dyer Point

Mine Operations

Ore Pad

Ore Pad Haul Road

Residential Area

Road to Waste Rock Pile 3

Stink Cove Sediments

Tailings Impoundment

Waste Rock Pile 1

Waste Rock Pile 2

Waste Rock Pile 3

Figure 1Potential Source Areas

0 800400

Feet

Docum

ent:

P:\P

roje

cts

\md

ot\C

alla

han

Min

e\6

.0G

IS\M

apD

ocu

men

ts\2

009

RI

Exe

cu

tive

Su

mm

ary

\Fact_

She

ets

_8

x1

1P

.mxd

PD

F:

P:\P

roje

cts

\md

ot\

Calla

ha

nM

ine

\6.0

GIS

\Fig

ure

s\F

actS

hee

tA

pri

l2

00

9\F

igu

re1

.pdf

04

/09/2

009

1:5

5P

Mdb

wild

es


¯Sedgwick

Blue Hill

Brooksville

Penobscot

Castine

!Ï Pore Water Sample

!Ï Piezometer

@A Overburden Monitoring Well

@A Overburden Hydraulic Control Monitoring Well

@A Bedrock Monitoring Well

Decant Pipe

Bathymetric Contour

Mine Waste in Sediment

Delineated Wetlands


}

}

}

}

}

}

»

»

»

»

Primary Crusher

Secondary Crusher

Lab

Mine Office

Shop (USTs)

PowderMagazine

Dam

Freshwater Pond

EffluentPond

Dyer Cove/Settling Pond

Sump

Sump

Water Tank

Concentrator Building

SumpPipe

Shaft 1

Shaft 2

Shaft 3

Shaft 4

10" pipe

16" pipe

6" pipe

6" pipe

6" pipe

Waste RockPile 3Waste Rock

Pile 1

Waste RockPile 2

Tailings Pile

Ore Pad

Legend

» Mine Shaft

Description

Purported Lateral Mine Shafts

The "920" and the "860"

Operations Piping

Water

Intermittent Water

Pre-Mine Shoreline Excavated

Figure 2Site Plan with Historic Features

0 800400

Feet

Do

cu

me

nt:

P:\P

roje

cts

\md

ot\C

alla

ha

nM

ine

\6.0

GIS

\Ma

pD

ocu

me

nts

\20

09

RI

Exe

cu

tive

Su

mm

ary

\Fa

ct_

Sh

ee

ts_

8x1

1P

.mxd

PD

F:

P:\P

roje

cts

\md

ot\

Ca

llah

an

Min

e\6

.0G

IS\F

igu

res\F

actS

he

etA

pri

l2

00

9\F

igu

re2

.pd

f0

4/0

9/2

00

92:0

7P

Md

bw

ilde

s


¯Sedgwick

Blue Hill

Brooksville

Penobscot

Castine

— 4 —


OU1 Remediation Areas:

Waste Rock Pile 3

Goose Pond Salt Marsh

Goose Pond and Goose Cove Sediment

Tailings Impoundment

Mine Operations Area

Ore Pad

Figure 3OU1 Remediation Areas

0 800400

Feet

Docum

ent:

P:\P

roje

cts

\md

ot\C

alla

han

Min

e\6

.0G

IS\M

apD

ocu

men

ts\2

009

RI

Exe

cu

tive

Su

mm

ary

\Fact_

She

ets

_8

x1

1P

.mxd

PD

F:

P:\P

roje

cts

\md

ot\

Calla

ha

nM

ine

\6.0

GIS

\Fig

ure

s\F

actS

hee

tA

pri

l2

00

9\F

igu

re3

.pdf

04

/09/2

009

3:2

4P

Mdb

wild

es


¯Sedgwick

Blue Hill

Brooksville

Penobscot

Castine

Legend

Delineated Wetlands

Bathymetric Contour


}

}

}

}

}

}

3.83.5

98

98

5.1

6.9

4.1

!Ï !Ï

!Ï

!Ï

!Ï%W

%W

%W%W

%W

%W

%W

@A

@A

@A

@A@A

@A

@A

@A@A

@A

@A

@A

@A

@A

!(!(

!(

!(!(

!(!(

!(!(

!(!(

!(!(

!(!(

!(!(

!(

!(

!(!(

!(

!(!(

MW-618R

MW-617R

MW-615R

MW-614R

MW-610R

MW-609R

MW-608R

MW-607R

MW-606R

MW-604R

MW-720R

MW-721R

MW-723R

MW-722R

5.34.9 D

165

5.0

13.9

19.3

4360

42900

6190

29.1

10.1

27.2

12ND D

14100

PW-705

PW-704

PW-703

PW-702

Legend

Background Mine Ops/Tailings Pile

Ore Pad/Mine

Waste Rock Pile 1 & 3

@A Bedrock Monitoring Well

!( Copper > MCL/MEG 1,300 ug/L

!( Lead > MEG 10 ug/L (MCL 15 ug/L)

!( Zinc > MEG 2,000 ug/L (MCL 5,000 ug/L)

!( Cadmium > MEG 3.5 ug/L (MCL 5.0 ug/L)

!( Arsenic >MCL/MEG 10 ug/L

!Ï Pore Water Sample

%W Copper > Marine AWQC 3.1 ug/L

%W Lead > Marine AWQC 8.1 ug/L

%W Zinc > Marine AWQC 81 ug/L

%W Cadmium >Marine AWQC 8.8 ug/L

%W Arsenic >Marine AWQC 36 ug/L

Figure 4Extent of Bedrock Groundwater Contamination

0 800400

Feet

Do

cu

me

nt:

P:\P

roje

cts

\md

ot\C

alla

ha

nM

ine

\6.0

GIS

\Ma

pD

ocu

me

nts

\20

09

RI

Exe

cu

tive

Su

mm

ary

\Fa

ct_

Sh

ee

ts_

8x1

1P

.mxd

PD

F:

P:\P

roje

cts

\md

ot\

Ca

llah

an

Min

e\6

.0G

IS\F

igu

res\F

actS

he

etA

pri

l2

00

9\F

igu

re4

.pd

f0

4/0

9/2

00

92

:38

PM

db

wild

es


¯Sedgwick

Blue Hill

Brooksville

Penobscot

Castine

— 6 —

Figure 2: Property Ownership Map

Smith Cove

Preservation Trust

(private owner)

Holbrook Island

Sanctuary

(State of Maine)

Residential

(private owners)

Goose Pond

Estuary

(State of Maine)

Goose

Cove

Key

Smith Cove Preservation Trust Property

Holbrook Island Sanctuary(Maine Department of Conservation)

Residential Properties(private owners)

Other Features

Goose Pond Estuary

Public Roads

Blue Hill

Sedgwick

Brooksville

Penobscot

Castine

Figure 5.3-2Model Simulation

Erosion Potential During 100-yearRain Event and Ebb Tide



¯ 0 500250Feet

Prepared/Date: BRP 03/05/08 Checked/Date: PSB 03/05/08

Doc

umen

t:P

:\Pro

ject

s\m

dot\C

alla

han

Min

e\6.

0G

IS\M

apD

ocum

ents

\200

8R

IRep

ort\R

I_M

odel

_Sim

ulat

ions

_11x

17P.

mxd

PD

F:P

:\Pro

ject

s\m

dot\C

alla

han

Min

e\4.

0P

roje

ctD

eliv

erab

les\

4.1

Rep

orts

\200

8R

IRep

ort\R

IRep

ortI

nter

nalD

raft\

Figu

res\

Figu

re5.

3-2

Ero

sion

100y

rRai

nE

bb.p

df03

/05/

2008

10:2

8A

Mbr

pete

rs

Legend


Blue Hill

Sedgwick

Brooksville

Penobscot

Castine


Erosion Potential During 100-yearStorm Surge and Flood Tide



¯ 0 500250Feet


Doc

umen

t:P

:\Pro

ject

s\m

dot\C

alla

han

Min

e\6.

0G

IS\M

apD

ocum

ents

\200

8R

IRep

ort\R

I_M

odel

_Sim

ulat

ions

_11x

17P.

mxd

PD

F:P

:\Pro

ject

s\m

dot\C

alla

han

Min

e\4.

0P

roje

ctD

eliv

erab

les\

4.1

Rep

orts

\200

8R

IRep

ort\R

IRep

ortI

nter

nalD

raft\

Figu

res\

Figu

re5.

3-3

Ero

sion

100y

rSur

geFl

ood.

pdf

03/0

5/20

0810

:34

AM

brpe

ters

Legend


Blue Hill

Sedgwick

Brooksville

Penobscot

Castine


Erosion Potential During 100-yearStorm Surge and Ebb Tide



¯ 0 500250Feet


Doc

umen

t:P

:\Pro

ject

s\m

dot\C

alla

han

Min

e\6.

0G

IS\M

apD

ocum

ents

\200

8R

IRep

ort\R

I_M

odel

_Sim

ulat

ions

_11x

17P.

mxd

PD

F:P

:\Pro

ject

s\m

dot\C

alla

han

Min

e\4.

0P

roje

ctD

eliv

erab

les\

4.1

Rep

orts

\200

8R

IRep

ort\R

IRep

ortI

nter

nalD

raft\

Figu

res\

Figu

re5.

3-4

Ero

sion

100y

rSur

geE

bb.p

df03

/05/

2008

10:3

2A

Mbr

pete

rs

Legend


Blue Hill

Sedgwick

Brooksville

Penobscot

Castine

Figure 5.3-5100-year Storm Surge Ebb TideCompared to 'Mine Waste' andXRF Copper Data in SedimentRemedial Investigation ReportCallahan Mine Superfund Site


¯ 0 10050Feet


Doc

umen

t:P

:\Pro

ject

s\m

dot\C

alla

han

Min

e\6.

0G

IS\M

apD

ocum

ents

\200

8R

IRep

ort\R

I_M

odel

_Sim

_Goo

se_C

ove_

11x1

7P.m

xdP

DF:

P:\P

roje

cts\

mdo

t\Cal

laha

nM

ine\

4.0

Proj

ectD

eliv

erab

les\

4.1

Rep

orts

\200

8R

IRep

ort\R

IRep

ortI

nter

nalD

raft\

Figu

res\

Figu

re5.

3-5

Goo

seC

ove

SED

.pdf

03/0

5/20

083:

57P

Mbr

pete

rs

Legend

$B SedimentMine Waste in Sediment

top depth Cu (mg/kg)0 1200

GC-05

top depth Cu (mg/kg)0 521 1302 273 224 ND5 ND6 44

SD-5104

top depth Cu (mg/kg)0 2001 232 ND3 ND4 25

SD-5105


1.5 20002 2700

2.5 26003 5304 ND6 ND8 ND9 21

SD-5106


0.5 ND

SD-5201

top depth Cu (mg/kg)0.4 2800.4 ND

SD-5202 top depth Cu (mg/kg)0 1300

0.5 34001.5 1100

2 740

SD-5203

top depth Cu (mg/kg)0 19001 3102 ND4 ND8 ND

SD-5204


0.3 52001 274 ND5 ND7 ND

SD-5206


0.5 32001.5 150

3 ND5 ND

SD-5205

top depth Cu (mg/kg)0.4 17000.7 25001.2 37001.6 340

2 472.4 ND2.8 ND

SD-5227 top depth Cu (mg/kg)0 5400

0.5 87001 7100

1.5 1903 ND5 ND8 40

SD-5207


0.5 1301.5 ND

3 ND5.5 ND

SD-5226


0.5 1301.5 ND

3 ND5.5 ND

SD-5226

Notes:1. ND - Non-Detect2. Gray shading indicates mine waste observed in sediment.

Table 1.1-1

Summary of Investigations

Year of

Investigation Principal Investigator Investigation Description Sampling Summary

2004 USEPA - TRC Initial Remedial Investigation 30 surface soil samples

12 surface water samples

1 seep sample

23 sediment samples

Bathymetry survey of Goose Cove and Goose Pond

Geophysical surveys to map bedrock

2005 Maine DOT - MACTEC Phase 1A 2005 Remedial Investigation 189 surface soil samples


13 seep samples

564 sediment samples

41 ecological sample locations

2006 Maine DOT - MACTEC Phase 1A 2006 Remedial Investigation 22 soil borings

16 piezocone penetrations

5 piezometers

14 overburden monitoring wells

10 bedrock monitoring wells

1 round residential drinking water sampling

2 rounds groundwater sampling

2 synoptic groundwater level surveys

4 air monitoring stations

Electromagnetic surveys

15 seep samples

7surface water samples

P:\Projects\mdot\Callahan Mine\4.0 Project Deliverables\4.1 Reports\2008 RI Report\_Final RI\Tables\Old\ Page 1 of 2

MDOT Callahan Mine Superfund Site – Remedial Investigation Report

MACTEC, Inc. Project No.: 3612062047

April 2009

Final

Table 1.1-1

Summary of Investigations

Year of

Investigation Principal Investigator Investigation Description Sampling Summary

2007 Maine DOT - MACTEC Phase 1B 2007 Remedial Investigation 12 soil borings

10 piezometers

9 overburden monitoring wells

4 bedrock monitoring wells

44 test pit excavations

1 round residential drinking water sampling

1 round groundwater sampling

1 synoptic groundwater level survey

9-month water elevation monitoring

5 seep samples

325 surface soil samples

103 sediment samples

55 subsurface soil samples


2008 Maine DOT - MACTEC Clam Tissue/Sediment 22 clam tissue samples

Bioavailability Study 22 sediment samples

Prepared/Date: SFC 06/25/07

Checked/Date: PSB 07/03/07

P:\Projects\mdot\Callahan Mine\4.0 Project Deliverables\4.1 Reports\2008 RI Report\_Final RI\Tables\Old\ Page 2 of 2



April 2009

Final

Table ES-3

Human Health Risk Assessment Summary

Exposure Point Current Future Current/Future Future Future

Resident Resident Recreational Visitor Recreational Angler Commercial Angler

ELCR HI PbBLD ELCR HI PbBLD ELCR HI PbBLD ELCR HI PbBLD ELCR HI PbBLD

Lot A Surface Soil 5E-05 1 a

> 10

Lot B Surface Soil 4E-05 0.7 < 10

Lot C Surface Soil 3E-05 1 > 10

Lot D Surface Soil 4E-05 2 > 10

Source Area Surface Soil 3E-03 58 > 10 1E-03 167 < 10

Source Area Subsurface Soil 3E-07 0.07

Halo Area Surface Soil 2E-05 1 < 10 7E-06 0.2 < 10

Freshwater Seeps 1E-08 0.1

Overburden Groundwater 1E-03 235 > 10

Bedrock Groundwater 1E-04 86 < 10

Goose Cove Surface Water 5E-09 0.001 9E-09 0.002 6E-08 0.01

Goose Cove Crustaceans (Crabs) b

3E-04 4 < 10 3E-04 4

Goose Cove Crustaceans (Lobster) b,c

2E-04 2 < 10 2E-04 3

Goose Cove Bivalves (Clams) c

9E-05 3 < 10 7E-05 2

Goose Cove Bivalves (Mussels) 1E-04 1 a

< 10 1E-04 1 a

Goose Pond Surface Water 5E-09 0.001 9E-09 0.002 6E-08 0.01

Goose Pond Sediment 3E-07 0.003 2E-06 0.03 < 10

Goose Pond (Irregularly Flooded) Sediment 2E-05 0.6 < 10 3E-06 0.03 < 10

Goose Pond Crustaceans (Crabs) c

1E-04 3 < 10 1E-04 4

Goose Pond Bivalves (Clams) 2E-05 0.6 < 10

Salt Marsh Sediment 1E-05 1 < 10

Marsh Creek Surface Water 1E-07 0.003

Marsh Creek Sediment 1E-07 0.001

Weir Cove Bivalves (Clams) b

2E-04 1 a

< 10 1E-04 1 a

Green shading indicates ELCR less than 1E-06, HI less than 1, or Pb BLD 10 µg/dL or less for 95% or more of the population.

Blue shading indicates ELCR between 1E-06 and 1E-04.

Red shading indicates ELCR greater than 1E-04, HI greater than 1, or Pb BLD greater than 10 µg/dL for more than 5% of the population.

Yellow shading indicates incremental risks are below a cancer risk of 1E-04 and a HI of 1.

[a] Based on target organ hazard index.

[b] Risks are due to arsenic; arsenic in biota tissue does not appear to be related to the Site. Incremental risks are below a cancer risk of 1E-04 and a hazard index of 1.

[c] Target organ hazard index does not exceed 1.

ELCR - Excess Lifetime Cancer Risk Prepared by / Date: KJC 03/10/08

HI - Hazard Index Checked by / Date: JHP 03/10/08

PbBLD - Geometric mean blood lead level Revised by / Date: KJC 10/23/08

P:\Projects\mdot\Callahan Mine\4.0 Project Deliverables\4.1 Reports\2008 RI Report\_Final RI\Tables\

_Table ES-3 Page 1 of 1



April 2009

Final

ES-31

Table ES-6

Ecological Risk Summary Matrix - Aquatic Exposure Areas

Receptor

Group

Assessment Endpoint Measurement Endpoints Inference

Weight*

Uncertainty Goose Cove Goose Pond Permanently Flooded Goose Pond Irregularly Flooded Salt Marsh Marsh Creek Weir Cove

AQUATIC HABITAT

1 Salt Marsh

Plants

Maintenance of plant communities in

the Salt Marsh exposure area that

were potentially affected by past

mining activities at the Site similar to

those communities found at the

reference site.

1A: Compare Site salt marsh sediment metal

concentrations to published sediment benchmarks

protective of vascular plants (Spartina ) and to

reference sediment concentrations.

L Bulk sediment concentrations may overestimate bioavailable

fraction.

Not evaluated Not evaluated Not evaluated Adverse population level effects possible from

cadmium and copper. HQs are low (1.1 to 2.8 based

on RME/CTE and NOAEL/LOAEL combinations.

Not evaluated Not evaluated

1B: Compare concentrations in Salt Marsh plant

tissue (Spartina ) to literature-based effects thresholds

and to reference locations

L/M Assumes tissue concentrations greater than reference result in

adverse effects and therefore overestimates risk.

Not evaluated Not evaluated Not evaluated Adverse population level effects possible for cadmium,

copper, and zinc. HQs are low (1.7 to 5.3) based on

RME/CTE combinations).


1C: Perform field surveys to determine if the Salt

Marsh Spartina population is significantly different

from reference populations.

M/H Assumes that physical parameters (flooding regime, salinity

range, natural sulfuric acid production, etc.) are consistent

between study and reference areas.

Not evaluated Not evaluated Not evaluated Salt marsh plants in locations of readily available harm

(RAH) located at the upland fringe of the salt marsh

are significantly different from reference salt marsh.

There is likely a high risk of harm to the salt marsh

plant community in areas of RAH.


Assessment Endpoint 1 Weight of Evidence

Conclusion

- - Not evaluated Not evaluated Not evaluated There is a high risk to salt marsh plants in areas of

RAH. The cause of the RAH is not known; it could be

due to an episodic event from a seep discharge, chronic

exposure to Site seeps or sediment hot spots, or other

natural non-chemical stressors. In other areas of the

salt marsh, risk of harm is unlikely. Areas of RAH

affects less than 0.5% of Salt Marsh habitat.

Benchmark comparisons may overestimate risk.


2 Benthic

Invertebrates

Maintenance of benthic invertebrate

communities at the Site similar to

those found at the reference site.

2A: Compare Site sediment AVS SEM concentrations

to toxicity thresholds and reference locations.

M AVS SEM data are better at predicting lack of toxicity than

predicting toxicity. Less than 5% of AVS SEM data are

above the uncertainty thresholds (>130 uMols/g) for lack of

toxicity.

Divalent metals not likely to be toxic and are not bioavailable.

Risk to the benthic macroinvertebrate community unlikely.

Divalent metals not likely to be toxic and are not bioavailable.


Divalent metals not likely to be toxic. Risk to the benthic

macroinvertebrate community unlikely.

Not evaluated Divalent metals not likely to be toxic and are

not bioavailable. Risk to the benthic


Divalent metals not likely to be toxic. Risk to the

benthic macroinvertebrate community unlikely.

2B: Perform laboratory toxicity tests to measure

survival and growth of two marine/estuarine benthic

invertebrates (the amphipod Leptocheirus

plumulosus and the polycheate Neanthes

arenaceodanta ) exposed to sediments collected from

Site exposure areas and

M/H Predators found in some replicates; tests performed at salinity

concentrations of 27 parts per thousand (ppt) while field conditions

in some exposure areas may be lower; only one reference sample

was collected for each exposure area; lab conditions not truly

representative of field conditions where biota have had the

opportunity to acclimate to ambient conditions.

No effect on Neanthes growth, or Leptocheirus growth and

survival. Ecologically significant effects to Neanthes

arenaceodanta growth at GC-05. Analysis of dose-response

scatter plots for copper, lead, and zinc did not identify a

potential effects driver. Sediment COPC concentrations at

GC-05 were lower than GC-04 and GC-06 which did not

exhibit ecologically significant effects; risk likely

overestimated.

Ecologically significant effects to survival and growth.

Integrating results of statistical analyses of sediment and

pore water concentration data with dose-response scatter

plots suggests that arsenic, cadmium, and copper may

occur in hotspots at GP-22 and GP-12. Pore water

evaluation suggests that copper and zinc may be

contributing to the toxicity at locations GP-22 and GP-

12. Ecologically significant effects were observed for

Leptocheirus survival at GP-07 and Leptocheirus

growth at GP-13; sediment COPC concentrations at GP-

07 and GP-13 were lower than other locations which did

not exhibit adverse ecological effects.

Possibility of risk to benthic invertebrates due to tissue

residual levels for clams in the hot spot area

containing mine waste and elevated copper, lead, and

zinc hot spot concentrations. Risk to benthic

macroinvertebrates in the remainder of the Goose

Pond Irregularly Flooded exposure area benthic

macroinvertebrate community is unlikely.

Not evaluated Not evaluated Not evaluated

2C: Compare tissue residue levels in benthic

invertebrates collected from Site exposure areas and

reference exposure areas to published tissue

benchmarks.

L/M Benchmark comparisons may overestimate risk; benchmarks

not available for between 4 and 5 COPCs (cadmium, copper,

plead, nickel, zinc), depending on tissue type.

Adverse population level effects to the benthic

macroinvertebrate community are unlikely.

Adverse population level risks to benthic

macroinvertebrate community unlikely. Possible adverse

population level risks to clams from lead does not signify

a community level risk considering other tissue types

evaluated in this measurement endpoint.

Adverse population level effects to the benthic

macroinvertebrate community possible from lead and

zinc based on two clam tissue samples located in the

hot spot area.

Not evaluated Not evaluated Adverse population level effects are not expected.

Risk to benthic macroinvertebrate community

unlikely.

2D: Compare the diversity and community structure

of benthic invertebrates in sediments from Site

exposure areas to reference locations.

M Assumes that study area conditions worse than reference

exhibit adverse effects even though they may actually fall

within natural variability.

Based on CSI, diversity and structure of benthic

macroinvertebrate community is consistent with reference.



macroinvertebrate community is consistent with

reference. Risk to the benthic macroinvertebrate

community unlikely


macroinvertebrate community is consistent with

reference. Risk to the benthic macroinvertebrate

community unlikely

Not evaluated Not evaluated Not evaluated


Conclusion

- - Overall unlikely risk to the Goose Cove benthic

macroinvertebrate community. Effects to Neanthes growth

did not correlate with sediment COPC concentrations.

Toxicity tests suggest that a hotspot area may occur in the

vacinity of GP-22 and GP-12 for arsenic, cadmium, and copper.

Pore water evaluation also suggests that copper and zinc may be

contributing to the toxicity at locations GP-22 and G-12. The

remainder of the Goose Pond Permanently Flooded area did not

show impairment to the benthic macroinvertebrate

community.The potential for risk to the benthic community in

the remainder of the Goose Pond Permanently Flooded is

unlikely.

Possibility of risk to benthic invertebrates due to tissue

residual levels for clams in the hot spot area containing mine

waste and elevated copper, lead, and zinc concentrations.

Risk to benthic macroinvertebrates in the remainder of the

Goose Pond Irregularly Flooded exposure area benthic

macroinvertebrate community is unlikely.

Not evaluated Risk to the Marsh Creek benthic


Risk to the Weir Cove benthic macroinvertebrate

community unlikely.

3 Water Column

Invertebrates

Maintenance of water column

invertebrate (zooplankton)

communities in Site surface waters

similar to those found in the

reference site

3A: Compare total and dissolved metal concentrations

in Site surface water to published surface water

benchmarks and reference locations.

M Benchmark comparisons may overestimate risk; total

concentrations not available in reference samples;

benchmarks available for only cadmium, copper, lead, nickel

and zinc.

Possible adverse population level effects possible from copper

and zinc. Low confidence in conclusions. Only 1 surface

water sample evaluated.

Possible adverse population level effects from copper and

zinc. Low confidence in conclusions.

Possible adverse population level effects from

cadmium, copper, nickel, and zinc. Low confidence in

conclusions. Only 1 surface water sample evaluated.

Not evaluated Risk to the water column invertebrate

community unlikely. HQs<1.

Not evaluated


Conclusion

- - High uncertainty and low confidence that adverse population

level effects are possible in Goose Cove.

High uncertainty and low confidence that adverse

population level effects are possible in the Goose Pond

Permanently Flooded exposure area.

High uncertainty and low confidence that adverse

population level effects are possible in the Goose Pond

Irregularly Flooded exposure area.

Not evaluated Risk to the Marsh Creek water column

invertebrate community unlikely.

Not evaluated

4 Fish Maintenance of fish communities in

aquatic Site exposure areas similar

to those found in reference locations.

4A: Compare total and dissolved metal concentrations

in Site surface water to published surface water

benchmarks and reference locations.

M Benchmark comparisons may overestimate risk; total

concentrations not available in reference samples;

benchmarks not available for all COPCs.

Possible adverse population level effects possible from copper

and zinc. Low confidence in conclusions. Only 1 surface

water sample evaluated.

Possible adverse population level effects from copper and

zinc. Low confidence in conclusions.

Possible adverse population level effects from

cadmium, copper, nickel, and zinc. Low confidence in

conclusions. Only 1 surface water sample evaluated.

Not evaluated Risk to fish unlikely. HQs <1. Not evaluated

4B: Compare tissue residue levels measured in whole

fish collected from the Site exposure areas to

published benchmarks and reference locations.

L/M Benchmark comparisons may overestimate risk; benchmarks

available for Cd, Cu, and Zn.

Risk unlikely. HQs<1. Risk unlikely. HQs<1. Possible adverse population level effects from copper. Not evaluated Risk to fish unlikely. HQs<1. Not evaluated

4C: Calculate fish condition factors and compare to

reference locations.

L Fish data biased to largest specimens to meet tissue sample

requirements, however bias applied equally across all

exposure areas and reference locations

Fish condition consistent with reference. Risk unlikely. Fish condition consistent with reference. Risk unlikely. Fish condition consistent with reference. Unlikely

risk.

Not evaluated Fish condition consistent with reference.

Unlikely risk.

Not evaluated


Conclusion

- - Risk to fish in Goose Cove unlikely. Risk to fish in the Goose Pond Permanently Flooded exposure

area unlikely, however, it is possible there maybe some risk to

fish in areas that exceed water quality criteria.

Risk to fish in the Goose Pond Irregularly Flooded exposure

area unlikely, however, it is possible there maybe some risk

to fish in areas that exceed water quality criteria.

Not evaluated Risk to fish in Marsh Creek unlikely. Not evaluated

P:\Projects\mdot\Callahan Mine\4.0 Project Deliverables\4.1 Reports\2008 RI Report\_Final RI\Tables\_Table ES-6 Page 1 of 2



April 2009

Final

ES-37

Table ES-6

Ecological Risk Summary Matrix - Aquatic Exposure Areas

Receptor

Group


Weight*

Uncertainty Goose Cove Goose Pond Permanently Flooded Goose Pond Irregularly Flooded Salt Marsh Marsh Creek Weir Cove

5 Insectivorous

Birds (estuarine)

Maintenance of insectivorous

populations at the Site similar to

those found in the reference site.

5A: Compare estimated daily dose for insectivorous

bird species (spotted sandpiper) based on ingestion of

prey in Site exposure areas to published avian

Toxicity Reference Values (TRVs) and to reference

locations.

M TRVs assume 100% of COPCs are bioavailable, likely

resulting in an overestimate of risk. Forage habitat would

normally be limited to sediment under two inches of standing

water do to their leg length; food chain model overestimates

ingestion from locations deeper than a few inches which

would not be accessible.

Adverse population level effects unlikely. Adverse population level effects unlikely. Possible adverse population level effects from copper

(high confidence) and lead (low confidence).

Possible adverse population level effects from copper. Adverse population level effects unlikely. Adverse population level effects unlikely.


Conclusion

- - Risk to insectivorous birds in Goose Cove unlikely. Risk to insectivorous birds in the Goose Pond

Permanently Flooded exposure area unlikely for those

areas outside of sediment hot spots.

Adverse population level effects from copper and lead

to insectivorous birds are possible in the Goose Pond

Irregularly Flooded exposure area sediment hot spots.

The contaminants associated with this risk are copper

(high confidence) and lead (low confidence).

Adverse population level effects are possible to

insectivorous birds in the Salt Marsh. The contaminant

associated with this risk is copper (high confidence).

Risk to insectivorous birds in Marsh Creek

unlikely.

Risk to insectivorous birds in Weir Cove unlikely.

6 Semi-Aquatic

Piscivorous

Birds

Maintenance of piscivorous



6A: Compare estimated daily dose for piscivorous

bird species (great blue heron) based on ingestion of



locations.


resulting in an overestimate of risk. Forage habitat would

normally be limited to sediment under two inches of standing

water do to their leg length; food chain model overestimates

ingestion from locations deeper than a few inches which

would not be accessible.

Adverse population level effects unlikely. Adverse population level effects unlikely for those areas

outside of sediment hot spots.

Possible adverse population level effects from zinc

(low confidence).

Possible adverse population level effects from copper

(high confidence) and zinc (low confidence).

Adverse population level effects unlikely. Possible adverse population level effects from

chromium (moderate confidence) and zinc (low

confidence).


Conclusion

- - Risk to piscivorous birds in Goose Cove unlikely. Risk to piscivorous birds in the Goose Pond Permanently

Flooded exposure area unlikely.

Adverse population level effects from zinc to

piscivorous birds are possible in the Goose Pond

Irregularly Flooded exposure area.The contaminants

associated with this risk is zinc (low confidence).

Adverse population level effects from copper and lead

to insectivorous birds are possible in the Salt Marsh

exposure area. The contaminants associated with this

risk are copper (high confidence) and zinc (low

confidence).

Negligible risk to piscivorous birds in Marsh

Creek

Low to moderate possibility of adverse population

level effects to piscivorous birds in Weir Cove.

7 Semi-Aquatic

Predatory Birds

Maintenance of predatory bird



7A: Compare estimated daily dose for predatory bird

species (osprey) based on ingestion of prey in Site

exposure areas to published avian Toxicity Reference

Values (TRVs) and to reference locations. Use

exposure and risk estimates for bald eagle

(Assessment Endpoint #9) as surrogate for predatory

birds, with emphasis on population-level effects rather

than effects on indi id als


resulting in an overestimate of risk.

Adverse population level effects unlikely. Adverse population level effects unlikely. Adverse population level effects unlikely. Adverse population level effects unlikely. Adverse population level effects unlikely. Adverse population level effects unlikely.


Conclusion

- - Risk to predatory birds in Goose Cove unlikely. Negligible Risk to predatory birds in the Goose Pond

Permanently Flooded exposure area unlikely.

Risk to predatory birds in the Goose Pond Irregularly


Risk to predatory birds in the Salt Marsh exposure

area unlikely.

Risk to predatory birds in the Marsh Creek

exposure area unlikely.

Risk to predatory birds in the Weir Cove exposure

area unlikely..

8 Semi-Aquatic

Mammals

Maintenance of semi-aquatic

mammal populations at the Site

similar to those found in the

reference site.

8A: Compare estimated daily dose for semi-aquatic

mammal (river otter) based on ingestion of prey in

Site exposure areas to published mammalian Toxicity

Reference Values (TRVs) and to reference locations.





Conclusion

- - Risk to semi-aquatic mammals in Goose Cove unlikely. Risk to semi-aquatic mammals in the Goose Pond

Permanently Flooded exposure area unlikely.

Risk to semi-aquatic mammals in the Goose Pond

Irregularly Flooded exposure area unlikely.

Risk to semi-aquatic mammals in the Salt Marsh


Risk to semi-aquatic mammals in the Marsh

Creek exposure area unlikely.

Risk to semi-aquatic mammals in the Weir Cove


9 Rare,

Threatened, and

Endangered

species

Protection of individual bald eagles

foraging in aquatic habitats at the

Site similar to those found in the

reference site.

9A: Compare estimated daily dose for predatory bird

species (bald eagle) based on ingestion of prey in Site

exposure areas to published avian Toxicity Reference

Values (TRVs) and to reference locations.

L/M TRVs assume 100% of COPCs are bioavailable, likely




Conclusion

- - Risk to bald eagles in Goose Cove unlikely. Risk to bald eagles in the Goose Pond Permanently


Risk to bald eagles in the Goose Pond Irregularly


Risk to bald eagles in the Salt Marsh exposure area

unlikely.

Risk to bald eagles in the Marsh Creek


Risk to bald eagles in the Weir Cove exposure area

unlikely.

Prepared by: AMR, 3/25/08

NOTES: Checked by: BJR, 3/25/08

* Measurement endpoints are assigned an inference weight for each of the attributes that account for strength of association between the assessment and measurement endpoints, data quality, and study design and execution. The relative importance is indicated by an attribute weighting factor following guidance provided by Met al. (1996).

AVS/SEM - acid volatile sulfide/simultaneously extracted metals

COPC- chemical of potential concern

EPC- exposure point concentration

LOAEL- lowest observed adverse effects level

TOC - total organic carbon

TRV-toxicological reference value

CSI - community site index

P:\Projects\mdot\Callahan Mine\4.0 Project Deliverables\4.1 Reports\2008 RI Report\_Final RI\Tables\_Table ES-6 Page 2 of 2



April 2009

Final

ES-38

Receptor

Group


Weight*

Uncertainty Source Halo

10A: Compare Site soil concentrations to

benchmarks protective of terrestrial plants and to

reference locations.

L Benchmark comparisons may overestimate risk; benchmarks not

available for the 3 VOC and SVOC COPCs.

High confidence of possible adverse population level effects from

aluminum, arsenic, cadmium, copper, lead, mercury, selenium,

silver, thallium, zinc, and PCBs.

Possible adverse population level effects from cadmium, copper, lead, and

zinc. Benchmark comparisons likely overestimate risk.

10B: Perform field surveys to determine if

terrestrial plant communities on-Site are

significantly different from terrestrial plant

communities at reference locations.

M Assumes that study area conditions that are worse than reference

conditions are indicative of adverse effects, even though they may

actually fall within natural variability therefore overestimating

risk.

High risk though most of the Source area lacks a suitable growth

medium to support plant growth.

Terrestrial plant communities are consistent with reference.


Conclusion

- - High risk of harm to the plant community at the Source area from

several metal and PCB COPCs.

Risk to Halo area plant community unlikely based on field surveys which

were given a higher weight than benchmark comparisons.

11A: Compare Site soil concentrations to

benchmarks protective of soil invertebrates and to

reference.

L Benchmark comparisons may overestimate risk; benchmarks not

available for the 5 VOC, SVOC, and PCB COPCs.

Possible adverse population level effects from copper, lead,

mercury, and zinc (high confidence).

High confidence of possible adverse population level effects from copper,

mercury, and zinc. Benchmark comparisons likely overestimate risk

11B: Compare tissue residue levels in terrestrial

invertebrates from the Site to published tissue

benchmarks and to reference locations.

L/M Effects benchmarks not available. Not evaluated Not evaluated

11C: Compare forest litter community data from the

Site to reference locations.

M Assumes that study area conditions that are worse than reference

conditions are indicative of adverse effects, even though they may

actually fall within natural variability therefore overestimating

risk.

Not evaluated Soil invertebrate communities are consistent with reference.


Conclusion

- - Adverse population level effects are possible from copper, lead,

mercury, and zinc (high confidence).

Risk to Halo area soil invertebrates unlikely based on field surveys which

were given a higher weight than benchmark comparisons.

12A: Compare estimated daily dose for omnivorous

song bird species (robin) based on ingestion of prey

in Site exposure areas to published avian Toxicity

Reference Values (TRVs) and to reference

locations.

M TRVs assume 100% of COPCs are bioavailable, likely resulting in

an overestimate of risk.

Possible adverse population level effects from copper, zinc, and

PCBs (high confidence), cadmium and lead (moderate confidence),

and antimony and selenium (low confidence).

Possible adverse population level effects from chromium, copper, lead,

selenium, and zinc (low to moderate confidence). Confidence decrease

with decreasing HQ values, which are low, ranging from 1.1 to 4.0 in the

CTE/LOAEL scenario.


Conclusion

- - Adverse population level effects possible. Omnivorous songbirds

not likely to forage in the Source area due to poor habitat for prey

species.

Possibility of adverse population level effects to omnivorous songbirds in

the Halo area is uncertain given that all CTE/LOAEL HQs <1. Food

chain models likely overestimate risk since TRVs assume 100% of

COPCs are bioavailable.

13A: Compare estimated daily dose for predatory

bird species (red-tailed hawk) based on ingestion of



locations.



Possible adverse population level effects from zinc and PCBs

(moderate to high confidence).

Adverse population level effects unlikely.


Conclusion

- - Moderate to high confidence of adverse population level effects

possible from zinc and PCBs. Predatory birds not likely to forage

in the Source area due to poor habitat for prey species.

Risk to predatory birds in the Halo area unlikely.

14A: Compare estimated daily dose for small

omnivorous mammal species (white-footed mouse)

based on ingestion of prey in Site exposure areas to

published mammalian Toxicity Reference Values

(TRVs) and to reference locations.



Possible adverse population level effects from arsenic, copper,

selenium, vanadium, zinc, and PCBs (high confidence), and

antimony, cadmium, lead, manganese, and thallium (moderate

confidence).

Possible adverse population level effects from arsenic, chromium, and

copper (low confidence). Confidence decreases with decreasing HQ

values, which are all <8 in the CTE/NOAEL scenario and are all <1 in the

CTE/LOAEL scenario.

Assessment Endpoint14 Weight of Evidence

Conclusion

- - Adverse population level effects possible. Omnivorous mammals

not likely to forage at the site due to poor habitat and sparse

vegetation.

Possibility of adverse population level effects to omnivorous mammal in

the Halo area from arsenic, chromium, and copper is uncertain given low

CTE/LOAEL HQs. Food chain models likely overestimate risk since

TRVs assume 100% of COPCs are bioavailable. Food chain models

likely overestimate risk since TRVs assume 100% of COPCs are

bioavailable.

15A: Compare estimated daily dose for small worm-

eating mammal species (short-tailed shrew) based

on ingestion of prey in Site exposure areas to

published mammalian Toxicity Reference Values

(TRVs) and to reference locations.



Possible adverse population level effects from arsenic, cadmium,

copper, lead, manganese, selenium, thallium, vanadium, zinc, and

PCBs (high confidence), and antimony and mercury (moderate

confidence).

Low confidence in adverse population level effects form arsenic,

chromium, and copper to small worm-eating mammals in the

Halo area.


Conclusion

- - Adverse population level effects possible. Worm-eating mammals

not likely to forage at the site due to poor habitat and sparse

vegetation.

Moderate to high confidence that adverse population level effects to small

worm-eating mammals are unlikely.

NOTES: Prepared by: AMR, 3/25/08

Checked by: BJR, 3/25/08

COPC- chemical of potential concern

LOAEL- lowest observed adverse effects level

NOAEL- no observed adverse effects level

TRV-toxicological reference value

Maintenance of a soil invertebrate

community in the terrestrial habitats at

the Site similar to those found nearby in

a reference site.

11

* Measurement endpoints are assigned an inference weight for each of the attributes that account for strength of association between the assessment and measurement endpoints,

data quality, and study design and execution. The relative importance is indicated by an attribute weighting factor following guidance provided by Menzie et al. (1996).

TERRESTRIAL HABITAT

13 Terrestrial

Predatory Birds

15 Terrestrial Small

Worm-Eating

Mammals

Terrestrial Small

Omnivorous

Mammals

Terrestrial

Insectivorous

Birds

10 Terrestrial

Plants

Table ES-7

Ecological Risk Summary Matrix - Terrestrial Exposure Areas

Maintenance of omnivorous

populations of songbirds at the Site

similar to those found at a reference

site.

Maintenance of predatory bird

populations at the Site similar to those

found at a reference site

Maintenance of terrestrial mammal


found in a reference area.

Maintenance of terrestrial mammal


found in a reference area.

12

14

Maintenance of plant communities

in terrestrial habitats at the Site

similar to those found in a

reference site.

Soil Invertebrates

P:\Projects\mdot\Callahan Mine\4.0 Project Deliverables\4.1 Reports\2008 RI Report\_Final RI\Tables\_Table ES-71 of 1



April 2009

Final

ES-39

PORT2008010b.cdr

Prepared by JPH Checked By AMR

Baseline Ecological Risk AssessmentCallahan Mining Superfund Site

Brooksville, Maine

MACTEC, Inc.

Figure 2-11Ecological Conceptual ModelSite

HaloArea

Historical

Blasting

Source Area

Mine Pit

Ore Pad,Mine Operations,

andWaste Rock

Piles

Tailings Pile

Win

dE

rosio

n

Leaching to Seeps

Surface Runoff

Groundwater Transport

Decanter Pipe Discharge

Historical Pumping and Dewatering

Tidal Transport

Goose Pond(permanently

flooded,irregularly

flooded, and salt marsh

areas)

GooseCove

Marsh CreekWeir Cove

HistoricalDrainage

Tidal Transport

Leaching to Seeps

Surface Runoff

Groundwater Transport

Table G-18Wildlife Exposure Models Used To Estimate Daily Contaminant Intake – Aquatic/Semi-

Aquatic Receptors

Baseline Ecological Risk Assessment

Callahan Mine Superfund SiteBrooksville, Maine

6/8/2006P:\W4-STATE\Callahan Mine\Eco\Food Chain\Appendix G Tables \EDI Equations - Aquatic.doc Page 1 of 3

Estimated Daily Intake

dietsedwatertotal EDIEDIEDIEDI ++=

Surface Water Ingestion

BW

EFSFFIRCEDI

waterwaterwater

***=

Incidental Sediment Ingestion

BW

EFSFFIRCEDI

sedsedsed

***=

Dietary Intake

fishinvertplantdiet EDIEDIEDIEDI ++=

Aquatic Plant Intake

BW

EFSFFPIRCEDI

plantfoodplantplant

****=

Aquatic Invertebrate Intake

BW

EFSFFPIRCEDI

invertfoodinvertinvert

****=

Fish Intake

BW

EFSFFPIRCEDI

fishfoodfishfish

****=

Parameter Definition Units Value

EDItotal Total estimated daily intake of a chemical for a receptor species

mg/kg-day calculated

EDIwater Total estimated daily intake of a chemical for a receptor


EDIsed Total estimated daily intake of a chemical via the incidental sediment ingestion pathway for a receptor


EDIdiet Total estimated daily intake of a chemical via the consumption of contaminated prey pathway for a



Aquatic Receptors




Parameter Definition Units Value

receptor

Cwater Chemical concentration in surface water mg/L chemical-specific

a

IRwater Drinking water ingestion rate L/day receptor-specific

b

SFF Site Foraging Frequency (ratio of foraging or home range to Site area)

unitless receptor-specific

b

EF Exposure Frequency (number of days present at Site/year)


b

BW Body weight kg receptor-specific

b

Csed Chemical concentration in sediment mg/kg (dw) chemical-specific

a

IRsed Ingestion rate of sediment kg/day receptor-specific

b

EDIplant Total estimated daily intake of a chemical via consumption of contaminated plants in the diet of a receptor


Cplantc

Chemical concentration in aquatic plant forage mg/kg (ww) chemical-specific

a

IRfood Food ingestion rate kg/day receptor-specific

b

Pplant Percentage of plant mass in the diet of a receptor unitless receptor-specific

b

EDIinvert Total estimated daily intake of a chemical viaconsumption of contaminated invertebrate prey in the diet of a receptor


Cinvertd

Chemical concentration in aquatic invertebrate prey mg/kg (ww) chemical-specific

a

Pinvert Percentage of invertebrate mass in the diet of a receptor


b

EDIfish Total estimated daily intake of a chemical via consumption of contaminated fish prey in the diet of a receptor


Cfishe

Chemical concentration in fish prey mg/kg (ww) chemical-specific

a

Pfish Percentage of fish mass in the diet of a receptor unitless receptor-specific

b

Notes:

a. Abiotic media exposure point concentrations are estimated as the average concentration.


Aquatic Receptors




b. Receptor-specific exposure parameters for aquatic and semi-aquatic wildlife endpointreceptor species are documented in Tables 3 through 7.

c. Chemical concentration of plant prey is estimated by multiplying the sediment EPC by the

aquatic plant BAF for a given chemical; BAFs are summarized in Table 16.d. Chemical concentration of aquatic invertebrate prey (i.e., crayfish and/or shellfish),

amphibians, and fish, will be directly measured.

Prepared by: BJRChecked by: ALF

Table G-21

Summary of Receptors for Food Chain Models


Callahan Mine Superfund Site

Brooksville, Maine

Exposure Media EPCsb

Receptor (a) Description Area (ha) HR (ha) SFF SW SD SOIL PLANT INV FISH BIRD MAM SW SD Soil PL INV

FISH/

AMPHIB BIRD MAM

Red-tailed hawk Source Area (T1) 30 202 0.149 Yes - Yes No No - Yes Yes M - Freshwater - M - - - E-lit E-lit

American robin Source Area (T1) 30 0.5 1 Yes - Yes Yes Yes - No No M - Freshwater - M E-lit E-lit - - -

Short-tailed shrew Source Area (T1) 30 0.39 1 Yes - Yes Yes Yes - No Yes M - Freshwater - M E-lit E-lit - - E-lit

White-footed mouse Source Area (T1) 30 0.077 1 Yes - Yes Yes Yes - No No M - Freshwater - M E-lit E-lit - - -

Red-tailed hawk Halo Area (T2) 225 202 1 Yes - Yes No No - Yes Yes M - Freshwater - M - - - E-lit E-lit

American robin Halo Area (T2) 225 0.5 1 Yes - Yes Yes Yes - No No M - Freshwater - M E-lit M-TI - - -

Short-tailed shrew Halo Area (T2) 225 0.39 1 Yes - Yes Yes Yes - No Yes M - Freshwater - M E-lit M-TI - - E-lit

White-footed mouse Halo Area (T2) 225 0.077 1 Yes - Yes Yes Yes - No No M - Freshwater - M E-lit M-TI - - -

Red-tailed hawk Background (T3) 1000 202 1 No - Yes No No - Yes Yes - - M - - - E-lit E-lit

American robin Background (T3) 1000 0.5 1 No - Yes Yes Yes - No No - - M E-lit M-TI - - -

Short-tailed shrew Background (T3) 1000 0.39 1 No - Yes Yes Yes - No Yes - - M E-lit M-TI - - E-lit

White-footed mouse Background (T3) 1000 0.077 1 No - Yes Yes Yes - No No - - M E-lit M-TI - - -

Eagle Goose Cove (A1) 41 150 0.273 Yes No - No No Yes No No M - - - - M-RG - -

Great blue heron Goose Cove (A1) 41 0.6 1 Yes Yes - No Yes Yes No No M M - - M-CC M-RG - -

River otter Goose Cove (A1) 41 295 0.139 Yes Yes - No Yes Yes No No M M - - M-CC M-RG - -

Spotted sandpiper Goose Cove (A1) 41 0.25 1 Yes Yes - No Yes No No No M M - - M-CC - - -

Eagle

Goose Pond

Permanently

Flooded (A2) 29 150 0.193 Yes No - No No Yes No No M - - - - M-MC - -

Great blue heron

Goose Pond

Permanently

Flooded (A2) 29 0.6 1 Yes Yes - No Yes Yes No No M M - - M-INV M-MC - -

River otter

Goose Pond

Permanently

Flooded (A2) 29 295 0.098 Yes Yes - No Yes Yes No No M M - - M-INV M-MC - -

Spotted sandpiper

Goose Pond

Permanently

Flooded (A2) 29 0.25 1 Yes Yes - No Yes No No No M M - - M-INV - - -

Eagle

Goose Pond

Irregularly Flooded

(A3) 11 150 0.073 Yes No - No No Yes No No M - - - - M-MC - -

Great blue heron

Goose Pond

Irregularly Flooded

(A3) 11 0.6 1 Yes Yes - No Yes Yes No No M M - - BSAF M-MC - -

River otter

Goose Pond

Irregularly Flooded

(A3) 11 295 0.037 Yes Yes - No Yes Yes No No M M - - BSAF M-MC - -

Spotted sandpiper

Goose Pond

Irregularly Flooded

(A3) 11 0.25 1 Yes Yes - No Yes No No No M M - - BSAF - - -

Eagle Salt Marsh (A4) 2.7 150 0.018 Yes No - No No Yes No No M-Seeps - - - - M-MC - -

Great blue heron Salt Marsh (A4) 2.7 0.6 1 Yes Yes - No Yes Yes No No M-Seeps M - - BSAF M-MC - -

River otter Salt Marsh (A4) 2.7 295 0.009 Yes Yes - No Yes Yes No No M-Seeps M - - BSAF M-MC - -

Spotted sandpiper Salt Marsh (A4) 2.7 0.25 1 Yes Yes - No Yes No No No M-Seeps M - - BSAF - - -

Eagle Marsh Creek (A5) 3.5 150 0.023 No No - No No Yes No No - - - - - E-lit - -

Great blue heron Marsh Creek (A5) 3.5 0.6 1 No Yes - No Yes Yes No No - M - - E-lit E-lit - -

River otter Marsh Creek (A5) 3.5 295 0.012 No Yes - No Yes Yes No No - M - - E-lit E-lit - -

Spotted sandpiper Marsh Creek (A5) 3.5 0.25 1 No Yes - No Yes No No No - M - - E-lit - - -

Exposure Area

Terrestrial Receptors and Exposure Areas

Aquatic Receptors and Exposure Areas

P:\W4-STATE\Callahan Mine\Eco\Food Chain\Appendix G Tables\

FoodChainSummary, Sheet1 Page 1 of 2

6/8/2006

Prepared by: BJR

Checked by: ALF

Table G-21

Summary of Receptors for Food Chain Models


Callahan Mine Superfund Site

Brooksville, Maine

Exposure Media EPCsb

Receptor (a) Description Area (ha) HR (ha) SFF SW SD SOIL PLANT INV FISH BIRD MAM SW SD Soil PL INV

FISH/

AMPHIB BIRD MAM

Exposure Area

Eagle Weir Cove (A6) 6.3 150 0.042 No No - No No Yes No No - - - - - E-lit - -

Great blue heron Weir Cove (A6) 6.3 0.6 1 No Yes - No Yes Yes No No - M - - E-lit E-lit - -

River otter Weir Cove (A6) 6.3 295 0.021 No Yes - No Yes Yes No No - M - - E-lit E-lit - -

Spotted sandpiper Weir Cove (A6) 6.3 0.25 1 No Yes - No Yes No No No - M - - E-lit - - -

Eagle

Background - Cove

(A7) 1000 150 1 Yes No - No No Yes No No M - - - - M-RG - -

Great blue heron

Background - Cove

(A7) 1000 0.6 1 Yes Yes - No Yes Yes No No M M - - M-CC M-RG - -

River otter

Background - Cove

(A7) 1000 295 1 Yes Yes - No Yes Yes No No M M - - M-CC M-RG - -

Spotted sandpiper

Background - Cove

(A7) 1000 0.25 1 Yes Yes - No Yes No No No M M - - M-CC - - -

Eagle

Background -

Permanently

Flooded (A8) 1000 150 1 Yes No - No No Yes No No M - - - - M-MC - -

Great blue heron

Background -

Permanently

Flooded (A8) 1000 0.6 1 Yes Yes - No Yes Yes No No M M - - M-INV M-MC - -

River otter

Background -

Permanently

Flooded (A8) 1000 295 1 Yes Yes - No Yes Yes No No M M - - M-INV M-MC - -

Spotted sandpiper

Background -

Permanently

Flooded (A8) 1000 0.25 1 Yes Yes - No Yes No No No M M - - M-INV - - -

Eagle

Background -

Irregularly Flooded

(A9) 1000 150 1 Yes No - No No Yes No No M - - - - M-MC - -

Great blue heron

Background -

Irregularly Flooded

(A9) 1000 0.6 1 Yes Yes - No Yes Yes No No M M - - E-lit M-MC - -

River otter

Background -

Irregularly Flooded

(A9) 1000 295 1 Yes Yes - No Yes Yes No No M M - - E-lit M-MC - -

Spotted sandpiper

Background -

Irregularly Flooded

(A9) 1000 0.25 1 Yes Yes - No Yes No No No M M - - E-lit - - -

Eagle

Background - Salt

Marsh (A10) 1000 150 1 No No - No No Yes No No - - - - E-lit M-MC - -

Great blue heron

Background - Salt

Marsh (A10) 1000 0.6 1 No Yes - No Yes Yes No No - M - - E-lit M-MC - -

River otter

Background - Salt

Marsh (A10) 1000 295 1 No Yes - No Yes Yes No No - M - - - M-MC - -

Spotted sandpiper

Background - Salt

Marsh (A10) 1000 0.25 1 No Yes - No Yes No No No - M - - E-lit - - -

b. M - measured value; E - estimated; lit - literature source; TI - Terrestrial Invertebrate; MC - mummichog; INV - maximum concentration of green crab, marine worm, and soft-shell clam;

CC - cancer crab; RG - rock gunnel; BSAF - Biota Sediment Accumulation Factor

P:\W4-STATE\Callahan Mine\Eco\Food Chain\Appendix G Tables\

FoodChainSummary, Sheet1 Page 2 of 2

6/8/2006

Prepared by: BJR

Checked by: ALF

Principles for Managing Contaminated Sediment Risk at ...

Documents

Transcript of Principles for Managing Contaminated Sediment Risk at ...