site: /mrp break- other: urs(1990 aoc) with the usepa region vii, under section 106(a) of cercla, as...

URS

DRAFT

Feasibility Study Work PlanMississippi River Pool 15

May 9, 2003

for

HAlcoa Davenport Works

4879 State StreetBettendorf, Iowa 52722-1047

Site: /MRP

Break-Other:

40166619

SUPERFUND RECORDS

URS Corporation263 Seaboard Lane, Suite 200

Franklin, TN 37067(615)771-2480

URS

DRAFT

Feasibility Study Work PlanMississippi River Pool 15

May 9, 2003

for

HALCOA

Alcoa Davenport Works4879 State Street

Bettendorf, Iowa 52722-1047

RECEIVED URS Corporation263 Seaboard Lane, Suite 200

(MAY 112QQ3 Franklin' ™37067iwrif •»-i.*v« (615)771-2480

SUPERFUND DIVISION

ALCOA

Alcoa Mill Products

4879 State StreetPO Box 1047Bettendorf, IA 52722-1047 USATel:1 3194592000

May 9, 2003

Mr. Jim ColbertUSEPA Region VII901 North Fifth St.Kansas City, Kansas 66101

Re: Mississippi River Pool 15 Feasibility Study Work Plan

Dear Jim:

Please find attached three copies of the Draft Feasibility Study Work Plan for Mississippi RiverPool 15. Please contact me at 563/459-1628 if you have any questions or need additionalinformation.

Yours truly,

Bud SturfeerDavenport Remediatio:

cc: Kirk Gribben, Alcoa Technical Center

RECEIVED

MAY 12 2003SUPERFUND DIVISION

TABLE OF CONTENTS

Executive Summary ES-1

1 Background 1-1

1.1 Purpose of Feasibility Study 1-11.2 Site Description 1-11.3 Background 1-11.4 Potential Contaminant Sources 1-21.5 Previous Investigations 1-3

1.5.1 U.S. Army Corps of Engineers (1983-84) 1-31.5.2 USEPA National Enforcement Investigations Center (1983) 1-31.5.3 Young-Morgan & Associates (1990) 1-31.5.4 1990 AOC Phase 1 1-41.5.5 1990 AOC Phase II 1-41.5.6 1990 AOC Phase III 1-41.5.7 Biannual Fish Surveys (1988-98) 1-51.5.8 Other Alcoa Field Investigations 1-6

1.6 MRP15 Ecological Risk Evaluation 1-71.7 MRP15 Human Health Risk Evaluation 1-8

2 Site Remedial Activities 2-1

2.1 Waste Oil Lagoon 2-12.2 Transformer Pits 2-12.3 Industrial Sewers 2-12.4 Facility Water Reclamation System 2-12.5 Outfall 006 2-22.6 Outfall 002/Wetland 2 2-22.7 Groundwater Containment 2-22.8 Light Bulb Disposal Area 2-2

3 Remedial Action Objectives 3-1

3.1 Scope and Purpose 3-13.2 Existing Institutional controls 3-13.3 Applicable or Relevant and Appropriate Requirements 3-1

3.3.1 Chemical-Specific ARARs 3-13.3.2 Action-Specific ARARs 3-13.3.3 Location-Specific ARARs 3-1

4 Remedial Alternatives to be Studied 4-1

4.1 No Further Action 4-14.2 No Further Action with Monitoring 4-1

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TABLE OF CONTENTS

5 Approach to Evaluating Remedial Alternatives 5-1

5.1 General Approach ;. :„ 5-15.2 Comparative Analysis of Alternatives 5-2

6 References 6-1

LIST OF TABLES

Table 1-1 - Summary of PCB Concentration in Fish TissueTable 1 -2 - Cancer Risk and Noncarcinogenic Hazard

LIST OF FIGURES

Figure 1-1 - Area MapFigure 1 -2 - Alcoa Facility Adjacent to MRP 15

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Executive Summary

Alcoa is submitting this Feasibility Study (FS) Work Plan for Mississippi River Pool 15(MRP 15) in accordance with the 1990 Administrative Order on Consent (1990 AOC) betweenAlcoa and United States Environmental Protection Agency (USEPA) Region VII. The FS WorkPlan is developed to outline the process for evaluating appropriate remedial alternatives based onresults of sediment and surface water investigations and human health and ecological riskassessments conducted at MRP 15, as promulgated in the 1990 AOC.

The sediment and surface water investigations were completed in three phases: Phase I involvedan investigation of potential sources to MRP 15; Phase II consisted of information gathering anda modeling exercise to identify key depositional areas; and Phase III was a comprehensiveinvestigation of the nature and extent of contamination of PCBs and other chemicals of interestin surface water, sediments and limited biota (native mussels and fish tissue). Fish tissue datawere collected on a biannual basis from 1988 through 1998. Results of these investigativestudies, completed in the mid to late 1990s, have determined the following:

• The cumulative effect is that previous onsite remedial efforts from the early 1980sthrough the 1990s have eliminated PCB discharges to the river since 1992;

• Surface sediment PCB concentrations have likewise attenuated prior to the 1995sampling effort to concentrations that are below 1 mg/kg on average throughout allportions of the study area. Elevated concentrations of other chemicals were detected,however, their detection was limited in extent, i.e., to the immediate vicinity of plantoutfalls;

• PCBs were not detected in mussel tissue;

• PCB concentrations in fish tissue have demonstrated a substantial decline from the mid-to late-1980s when fish were first collected until 1998 when levels were below 1 mg/kgon average for each sampling station. Declines in observed fish tissue concentrationswere sufficient to warrant removal of a fish advisory for carp and carpsucker on MRP 15by the State of Iowa.

The human health risk assessments indicated that ingestion offish containing PCBs posed thegreatest exposure and risk. However, carcinogenic risks are within an acceptable target range.Although noncancer hazards exceeded 1, they are similar to the hazard levels associated with thereference area. There were no significant ecological risks identified.

This will be a focused FS because no significant risks above background were identified.Remedial alternatives to be evaluated in the MRP 15 FS include the "No Further Action"alternative and No Further Action with Monitoring (Natural Attenuation). Institutional controlsalready in place at the Alcoa facility would be maintained under both of these alternatives. Inaddition, these remedial alternatives will also recognize other previous and ongoing remedialactivities that have been undertaken by Alcoa. These include:

• Closure of the Waste Oil Lagoon• Cleaning transformer pits and sewer lines• Wastewater recycle and carbon treatment of the discharge• Groundwater containment• Maintenance activities at the Light Bulb Disposal Area

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Executive Summary

• Removal actions in Outfall 002 and Wetland 2.• Sediment removal and weir relocation in Outfall 006

Physical actions within the river itself will not be evaluated since low risks were concluded in therisk assessments and there are no current pathways of concern associated with any historicalreleases to the river.

In accordance with the National Oil and Hazardous Substances Pollution Contingency Plan, eachalternative will be evaluated in the context of effectiveness, implementability, and cost (40 CFR§300.430(f)).

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SECTIONONE Background

1.1 PURPOSE OF FEASIBILITY STUDY

USEPA Region VII has indicated that, in accordance with the 1990 Administrative Order onConsent (1990 AOC), and based on the findings of the Human Health Risk Assessment (HHRA)(URSGWC 2000a), and the Ecological Risk Assessment (ERA) (URS 2002), a Feasibility Study(FS) is necessary to evaluate appropriate response actions for Mississippi River Pool 15(MRP 15). The FS will provide evaluation of remedial alternatives protective of human healthand the environment and recommend an alternative to be implemented at the site.

1.2 SITE DESCRIPTION

Alcoa operates one of the world's largest aluminum sheet and plate rolling mills, known as theDavenport Works, in Scott County of east-central Iowa. The facility also produces aluminumingots for the rolling process. The Alcoa-Davenport Works is located in Riverdale, adjacent toBettendorf (one of the Iowa-Illinois Quad Cities) on a roughly rectangular, 445-acre tractadjacent to the Mississippi River (Figure 1-1). Since its original construction and start ofoperations in 1948, the Alcoa-Davenport Works has steadily grown and the expansion continues.Historic activities at the facility have led to releases of hazardous substances as designated underthe Comprehensive Environmental Response, Compensation and Liability Act (CERCLA).Some of the constituents of these releases are known or suspected to have migrated to onsiteoutfalls, wetlands, and Mississippi River Pool 15 (MRP 15). MRP 15 is approximately ten mileslong, covers 3,600 acres and is bounded by Federal Locks and Dams 14 (upstream) and 15(downstream). Widths of the river range from about 2,600 to 4,000 feet near the Alcoa facility.Water depth ranges to 21.6 feet.

1.3 BACKGROUND

In July 1990, Alcoa entered into an Administrative Order on Consent, Docket No. VII-90-F-0027(1990 AOC) with the USEPA Region VII, under Section 106(a) of CERCLA, as amended by theSuperfund Amendments and Reauthorization Act of 1986 (SARA). The AOC requires that arisk assessment of MRP 15 be conducted following completion of sediment investigations inonsite outfalls and wetlands and in MRP15. The 1990 AOC was amended on September 9, 1996to enable Alcoa to conduct human health and ecological risk assessments of MRP 15.

A phased approach has been used to collect data on potential contaminants within the onsiteoutfalls and wetlands and in MRP 15, as specified in the 1990 AOC. A Sediment/SoilInvestigation Studies [SIS] Work Plan (YMA 1991) addressed the nature and scope of the overallinvestigation and was approved by USEPA in July 1991. The following phases were defined inthe Work Plan to comply with the requirements of the Consent Order:

1) Phase I: Definition of potential sources of contamination from the Alcoa-Davenport Works facility to MRP15.

2) Phase II: Hydraulic and sediment modeling to define the critical studyarea(s) within MRP 15.

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3) Phase III: Quantification of vertical and horizontal extent of contaminationwithin the critical study area(s).

4) PhaselV: Feasibility Study, if warranted by the SIS.

Phases I, II and III are complete. Studies were conducted by Alcoa to assess onsite outfalls andwetlands (Phase I) and a report was prepared to delineate Critical Study Areas (CSAs) in MRP 15(Phase II). Field work for Phase III was completed in autumn 1995 and primarily consisted ofsampling and analyses for potential contaminants in sediments and surface water throughout theCSAs, an upstream reference area, and the lower reaches of certain tributary creeks.Quantitative surveys of freshwater mussels were also performed in MRP 15 adjacent to the Alcoafacility and a reference area, and representative samples of mussels were analyzed forpolychlorinated biphenyls (PCBs). The final Phase III report Sediment and Water Sampling ResultsPhase III Mississippi River Pool 15 Alcoa-Davenport Facility (WCC 1996) was approved byUSEPA on August 13,1996.

The 1990 AOC also required biannual sampling and analyses of PCBs in tissues of certain fishspecies from specified sites in MRP 15, a continuation of activities begun by Alcoa in 1988. Sixrounds of fish sampling/analysis have been completed (1988, 1990, 1992, 1994, 1996, 1998).

Two wetlands were identified in conjunction with Phase I of the 1990 AOC, designated asWetland 1 and Wetland 2 (Figure 1-2). Wetland 1 lies along MRP 15 and is included in theMRP 15 evaluation. Wetland 2 is offset from MRP 15 and lies within the boundaries of theFacility Site Assessment (FSA) Units (specifically, the Eastern Historical Disposal Area).Evaluation of potential ecological risks in Wetland 2 were assessed in conjunction with the FSAUnit ecological risk evaluation under a separate 1995 AOC.

Following completion of the first three phases outlined under the 1990 AOC as outlined above,human health and ecological risk assessments were conducted using data collected from MRP 15(including Wetland 1). The human health risk assessment was approved by USEPA on June 22,2000. The ecological risk assessment was approved by USEPA in March 2003.

This Work Plan is being prepared to address Phase IV, the Feasibility Study, as outlined under the1990 AOC.

1.4 POTENTIAL CONTAMINANT SOURCES

COPCs and COPECs in MRP15 have conceivably originated from a number of onsite areas.These areas, termed Facility Site Assessment (FSA) Units, have been evaluated under a 1995AOC. FSA Units that lie adjacent to MRP 15 are shown in Figure 1-2. Contaminant migrationpathways from potential source areas include direct discharge via the facility NPDES discharge,surface water runoff during precipitation events, and groundwater transport. Among the FSAUnits, Historical Unit (HU) areas are defined as areas where historical releases have occurredand include former lagoons, landfills, underground storage tanks (USTs), process areas, andareas of historical contamination. By definition, the historical units are no longer in use. CurrentWaste Management (CWM) Areas are in use at the facility and include process water andindustrial waste treatment facilities, active landfills, waste management areas, sewers, andoutfalls. Industrial Process (IP) units are those which are currently in use as production areas atthe facility and include such areas as the Hot Rolling Mill, Plate Mill, Cold Mill, various

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finishing lines, and other areas. A description of each HU, CWM, and IP area is provided in theFacility Site Assessment report (Geraghty & Miller 1992). Detailed descriptions and evaluationsof the various FSA Units have all been completed under the 1995 AOC.

1.5 PREVIOUS INVESTIGATIONS

An overview of investigations that have been conducted in MRP 15 are presented in thefollowing sections.

1.5.1 U.S. Army Corps of Engineers (1983-84)

The Rock Island District, U.S. Army Corps of Engineers (USCOE) sponsored sampling andanalyses of bulk surficial sediments and mussel (bivalve mollusk) tissues in 1983 and 1984(USCOE 1984). Sediments were sampled at 11 sites above, adjacent to, and below the "possiblepollution source" (Alcoa facility), as well as in the vicinity of sensitive downstream sites(municipal water intakes). Mussels were collected in the general vicinities of five of thesediment-sampling locations.

1.5.2 USEPA National Enforcement Investigations Center (1983)

USEPA's National Enforcement Investigations Center (NEIC) conducted a PCB contaminationstudy of MRP 15 in 1983 (USEPA 1983). Bulk surficial sediments were sampled at 21 locationsin Pool 15 and two locations in the upper portion of Pool 16. Surface water was collected nearthe river bottom at six locations, as well as from an oil slick adjacent to Alcoa. Edible tissues(filets) of common carp and channel catfish were sampled from six general areas. Hatchery-reared juvenile channel catfish were exposed for varying periods up to six days in cages placed at10 locations. Qualitative samples of benthic macroinvertebrates were collected by undefinedmethods at nine locations to compare community composition and diversity.

1.5.3 Young-Morgan & Associates (1990)

From 1988 to 1990, Young-Morgan & Associates (YMA) collected sediment samples for PCBanalyses in the Mississippi River adjacent to Alcoa (YMA 1990). In October 1988, sampleswere collected along a 2,000-ft reach centered offshore from the closed waste oil lagoon. A yearlater, sediment samples were collected adjacent to the Iowa-Illinois Gas and Electric Company's1

ash pond located along the upstream end of Alcoa property, as well as from mudflat areasupstream and downstream from the ash pond. In November 1989, additional sediment sampleswere collected from the mouth of Alcoa's National Pollutant Discharge Elimination System(NPDES) Outfall 006 and from upstream of the facility discharges.

The Iowa-Illinois Gas and Electric Company is now the Mid-America Energy Company.

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1.5.4 1990 AOC Phase I

Sampling was conducted during 1992 by Woodward-Clyde Consultants2 (WCC) to assess bulk-sediment and surface-water contamination within on-site drainages (outfalls) and two on-sitewetland areas at the Alcoa-Davenport Works. This survey was part of Phase I of the iterativeSIS approach outlined in Subsection 1.3, and resulted in a report titled Onsite Sediment SamplingResults, Phase IA - SIS, Alcoa-Davenport Facility (WCC 1993). In each of six NPDES outfalls,bulk sediments were sampled with a hand-coring device at 300-ft intervals. Counting fieldduplicates, this resulted in 48 sediment samples from 37 locations along the six outfalls. Theoutfalls vary in length from 300 to 3800 feet. Seven sediment samples were collected fromWetland 1. Twenty surface-water grab samples were collected from the outfalls and three weretaken from Wetland 1. The sediment and surface-water samples were analyzed using approvedUSEPA methods (CLP protocols) for Target Compound List (TCL) and Target Analyte List(TAL) constituents. Phase IA of the SIS was approved by USEPA on April 20, 1994. Results ofthe Phase 1A-SIS were used to identify target chemicals warranting evaluation in MRP15 insubsequent phases.

1.5.5 1990 AOC Phase II

Identification and delineation of critical study areas (CSAs) in MRP 15 was presented inSediment/Soil Investigation Studies: Phase II Delineation of the Critical Study Area (WCC1994). CSAs were selected by identifying areas believed to be conducive to sedimentation basedon river morphological characteristics and historical data. An historical database was developedconsisting of sediment dredging records, river stage and depth information; physical andchemical sediment characteristics; sediment depth; suspended sediment characteristics; rivervelocity; profiles and historical river bottom features/contours.

Based on the Phase II investigation, and in subsequent discussions with USEPA, fivediscontinuous areas were selected for further evaluation in Phase III of the SIS investigation. PhaseII of the SIS was approved by USEPA on April 20, 1994.

1.5.6 1990 AOC Phase III

Sampling was conducted by WCC in autumn 1995 to further assess bulk sediment and surfacewater quality in MRP 15, the lower reaches of selected tributary creeks, and an upstreamreference area. This study was Phase III of the SIS mandated by the 1990 AOC. Sampling wasfocused in the five discontinuous Critical Study Areas (CSAs) established in Phase II (WCC1994). Analytes for the Phase III SIS consisted of 46 chemicals of interest (COIs) that wereselected based on a list of preliminary COPECs developed for USEPA by Jacobs EngineeringGroup, Inc. (JEG 1994).

The frequency and spatial distribution of sample collection varied by analyte and CSA. Ingeneral, samples for PCBs and PAHs were collected in all study areas, while targeted volatileorganic compounds (VOCs), phenolic compounds, and inorganics were collected in the referencearea and in the immediate vicinities of the Alcoa outfalls. Sediment samples were randomly

Young-Morgan & Associates (YMA) became part of Woodward-Clyde Consultants (WCC) in late 1991.



collected from the surface (0-6 in) and subsurface (6-24 in.) along 150-ft transects orientedperpendicular to the shore. Water samples were collected with a beta-bottle designed forsampling trace organics and inorganics. Mussels were also collected for PCB analyses fromCSA No. 1 (located adjacent to and immediately downstream from the Alcoa facility) and theupstream reference area.

The final Phase III report Sediment and Water Sampling Results Phase III Mississippi River Pool 15Alcoa-Davenport Facility (WCC 1996a) was approved by USEPA on August 13, 1996.

1.5.7 Biannual Fish Surveys (1988-98)

As a continuation of efforts begun by in 1988 by Alcoa, the 1990 AOC required biannualsampling and analyses of PCBs in filets from seven species offish of specified minimum sizes.There were initially (1988 and 1990) five targeted sampling areas (stretches of river), includingtwo areas adjacent to the Alcoa facility, an area bracketing the mouth of Duck Creekimmediately downstream from Alcoa, and two reference areas substantially removed fromAlcoa. In 1992, 1994, 1996 and 1998 only one of the reference sites was sampled. Despitesubstantial efforts during each of the first three surveys, three of the seven targeted species werenever caught in sufficient numbers at all sites to support meaningful statistical comparisons.Additionally, results for two of the original target species were shown to be statistically alike.Therefore, in 1994 USEPA approved a reduction in the target list of fishes to common carp(Cyprinus carpio), river carpsucker (Carpiodes carpio), and channel catfish (Ictaluruspunctatus).

An evaluation of the fish tissue data collected by Alcoa over the period from 1988 to 1998demonstrated that PCB concentrations in fish collected adjacent to the Alcoa facility havesubstantially decreased over time and are approaching concentrations characteristic offish fromthe reference area (URSGWC 1999). The following table summarizes data from Sites 2, 3 and 4adjacent to the Alcoa facility, as compared to fish collected from the reference area between1988 and 1998.

TABLE 1-1SUMMARY OF PCB CONCENTRATIONS IN FISH TISSUE

Location and Time PeriodPCB Concentration in Filet

Mean (95% UCL)mg/kg

Reference Area (1988a)

Sites 2, 3 and 4(1988")

Reference Area (1998b)

Sites 2, 3and4(1998b)

Channel Catfish0.22 (0.27)

1.10(1.31)

0.33 (0.40)

0.33 (0.40)

Common Carp0.32 (0.39)

3.72 (4.65)

0.41 (0.57)

0.34 (0.44)

River Carpsucker0.25 (0.32)

16.62(25.91)

0.17(0.23)

0.35 (0.42)a Data for river carpsucker from 1990: insufficient fish were captured from the reference area during 1988b Data for channel catfish from 1996, the last year channel catfish were collected.



Though natural attenuation processes (weathering, floods, degradation) undoubtedly have playeda role, the reductions in fish tissue concentrations have occurred in conjunction with andfollowing on-site PCB source reduction measures implemented by Alcoa during the mid-1980sand early 1990s. These measures have had the net effect of eliminating measurable discharges ofPCBs to the river. The major actions taken include closure of the former waste oil lagoon,operation of a groundwater containment system, cleaning stormwater sewer lines andtransformer pits, and most recently, significant reductions in process wastewater discharges andapplication of activated carbon treatment of all process wastewater that is discharged from thefacility. Concentrations of PCBs routinely measured as part of the NPDES program essentiallydisappeared in the early 1990s. Elimination of PCB discharges to the river has allowed fornatural attenuation processes which have resulted in statistically significant reductions insediment PCB concentrations in MRP 15. As a result of these control measures, PCB reductionsin fish tissue have been so substantial that concentrations in fish adjacent to the Alcoa facility arenow comparable to those collected from the reference area (Table 1-1).

Also as a result of the dramatic decline in fish tissue PCB concentrations, the Iowa Departmentof Natural Resources formally lifted a fish consumption advisory in July, 2000 that had been inplace in MRP15 along the Iowa shoreline for common carp since 1989, and for river carpsuckersince 1990.

1.5.8 Other Alcoa Field Investigations

Supplemental data were collected by Alcoa concurrent with biannual fish investigations inSeptember 1996 to support risk assessment activities for MRP 15. A Field Sampling Plan titledSupplemental Field Investigations in Support of Risk Assessment Activities Mississippi RiverPool 15 was submitted to USEPA in August 1996 (WCC 1996b). The program includedcollection offish filets and wholebody tissue analyses and benthic macroinvertebrates samplesfrom MRP 15, and sediment samples from Wetland 1. Results of the supplemental investigationwere submitted to USEPA in the Supplemental Field Investigations in Support of RiskAssessment Activities Mississippi River Pool 15 (WCIA 1997).

Additional surface water samples also were collected from Wetland 1 in May 1999. Based onsurface water samples collected from Wetland 1 in 1991, PCBs (Aroclor 1260), iron and manganesewere identified as COPECs in the Chemicals of Potential Concern and Chemicals of PotentialEcological Concern Memorandum (WCIA 1998a). These reported values were likely associatedwith suspended sediments and not representative of bioavailable concentrations in the watercolumn. The 1991 data were also collected prior to improvements in the facility wastewatertreatment system. Sedimentation also appears to be modifying the character of Wetland 1 byreducing the amount of standing water and shifting the area to a more terrestrial habitat. This isprobably the result of the position of the Ash Pond and Alcoa water intake structure that producea morphologic backwater, which is conducive to reduced water velocities, and subsequentlyresults in the settling of suspended solids from the water column in this area. The additionalsurface water samples in May 1999 were collected to obtain data more representative of currentconditions and representing the bioavailable fraction.



1.6 MRP15 ECOLOGICAL RISK EVALUATION

The MRP 15 ecological risk assessment evaluation consisted of a series of deliverables preparedby Alcoa for submission to USEPA. These included:

• Chemicals of Potential Concern and Chemicals of Potential Ecological ConcernMemorandum (WCIA 1998a)

• Ecological Problem Formulation Memorandum (URSGWC 2000b)• Ecological Risk Assessment Report (URS 2002)

In agreement with USEPA, another document, the Ecological Risk Analysis Memorandum, wasincorporated directly into the Ecological Risk Assessment Report. The Chemicals of PotentialConcern and Chemicals of Potential Ecological Concern Memorandum selected the chemicalsupon which the MRP15 investigation was focused. The Ecological Problem FormulationMemorandum established the goals, scope and focus of the risk assessment and identifiedassessment endpoints and conceptual models. Candidate receptors and measures of effect wereselected that were used to evaluate the assessment endpoints.

Based on the problem formulation process and selection of assessment endpoints, four riskhypotheses (risk questions) were developed for MRP 15 and Wetland 1. The Risk Hypothesesand associated findings are discussed below.

Mississippi River Pool 15

Risk Hypothesis 1 - Are bulk sediment concentrations of carbon disulfide, phenol, carbazole,LMW PAHs, HMW PAHs, copper, lead, manganese, or zinc sufficient to reduce survival,growth or reproduction of benthic invertebrates? It was concluded that PAH concentrations aresufficiently elevated on a localized basis and may reduce benthic invertebrate biomass in theimmediate vicinity of Outfall 004. This is not believed to be ecologically significant because:

• This area is extremely small in extent (i.e., along about 100 ft of shoreline), and there is noindication of a reduction in biomass when the study areas are evaluated en toto;

• The potentially affected area was located within the mixing zone associated with Outfall 004(Note, since the time of the investigation Outfall 004 was converted to a stormwater onlydischarge);

• Biodegradation and natural river geohydrologic processes, such as dispersion, erosion, andburial are expected to reduce these localized concentrations, and subsequently impacts, overtime.

Risk Hypothesis 2 - Are concentrations of PCBs accumulated in prey item tissues sufficient toimpair reproduction and/or development of carnivorous birds or river otters? The beltedkingfisher, great blue heron, spotted sandpiper and river otter were selected as candidatereceptors to evaluate PCBs in MRP15 for Risk Hypothesis 2. It was concluded that PCBs do notpose risks to piscivorous birds or mammals or shoreline/probing birds.



Wetland 1

Risk Hypothesis 3 - Are bulk sediment concentrations of carbazole, dibenzofuran, LMW PAHs,HMW PAHs, chromium, copper, manganese, or zinc sufficient to reduce survival, growth orreproduction of benthic invertebrates? Based on low risk potentials and toxicity limiting factorsin wetland sediments (such as hydric conditions, high total organic carbon, and depositionalcharacteristics), it was concluded that it is unlikely that there are risks to benthicmacroinvertebrates in Wetland 1.

Risk Hypothesis 4 - Are PCBs in prey items and sediments sufficiently elevated to impairreproduction and/or development of carnivorous birds? The great blue heron, mallard duck andspotted sandpiper were selected as candidate receptors. It was concluded that PCBs do not posesignificant risks to carnivorous and omnivorous birds that may forage in Wetland 1.

The overall conclusion for the ecological risk assessment is that no unacceptable ecological riskswere identified in MRP 15 or Wetland 1.

1.7 MRP15 HUMAN HEALTH RISK EVALUATION

The human health risk assessment of MRP15 was presented in a series of reports:

• Chemicals of Potential Concern and Chemicals of Potential Ecological ConcernMemorandum (WCIA 1998a)

• Human Health Exposure Assessment Memorandum (WCIA 1998b)• Human Health Risk Assessment Report (URSG WC 2000a)

Three exposure scenarios considered representative of site-specific conditions were identified forquantitative assessment in the investigation, as summarized in the Human Heath ExposureAssessment Memorandum (WCIA 1998b).

(1) Shoreline Fishermen - an angler that catches and consumes fish from a shoreline fishingarea near Duck Creek;

(2) Recreational Boat Fisherman - an angler that catches and consumes fish from theshoreline area near Alcoa. This receptor may also contact chemicals detected in near-shore sediments and surface water when wading to the shoreline.

(3) Shoreline Trespasser - an individual that may trespass onto Alcoa private property andcontact contaminated sediments and surface water within onsite wetlands.

PCBs were identified as the primary COPCs associated with potential human health risks in theChemicals of Potential Concern and Chemicals of Potential Ecological Concern Memorandum(WCIA 1998a). To evaluate human health risks, site-specific information was used to developfish ingestion rates, and reasonably conservative assumptions of toxicity and exposure to surfacewater and sediments were developed as outlined in the Human Health Exposure AssessmentMemorandum (WCIA 1998b).

A summary of cancer risk estimates and noncancer hazard indices as presented in the HumanHealth Risk Assessment Report is presented in the following table.



TABLE 1-2CANCER RISK AND NONCARCINOGENIC HAZARD

Exposure Scenario

Central Tendency Exposure

Recreational Boat Fisherman

Recreational Shoreline Fisherman

Shoreline Trespasser'

Reference Area

Reasonable MaximumExposure

Recreational Boat Fisherman

Recreational Shoreline Fisherman

Shoreline Trespasser1

Reference Area

Total Cancer Risk

4.1 x 10'6

4.2 xlO'6

3.4 xlO'8

4.0 x 1(T6

4.2 x 10'5

4.7 xlO' 5

l .Sx lO ' 6

4.3 x 1(X5

Total Hazard Index

0.85-1.2

0.84-1.2

0.003 - 0.006

0.83-1.2

1.6-2.2

1.6-2.5

0.019-0.039

1.7-2.3

Total cancer risk includes sum of risk attributable to PCBs and benzo(a)pyrene. Noncancer hazardrepresents PCBs only.

Results indicate that using reasonably conservative assumptions, cancer risk was found to bewithin acceptable ranges for the recreational boat fisherman that might catch and consume fishadjacent to the Alcoa facility, as well as for the shoreline fisherman along Duck Creek. There isa low potential for noncancer hazards, namely a risk for developmental effects, for therecreational and shoreline fisherman. However, identical noncancer hazards are also associatedwith those who consume fish exclusively from the reference area. Based on the results of theHHRA, the following conclusions are drawn:

• PCB source reduction efforts to date have been very effective in reducing potentialrisks to anglers in MRP 15.

• Measures already implemented by Alcoa are likely to have contributed significantlyin the reductions noted in fish concentrations from 1988 to 1998.

• Risks posed by fish in MRP15 are similar to those posed by fish that are caught andconsumed from other locations in the Mississippi.


SECTIONTWO Site Remedial Activities

Several activities have been conducted by Alcoa that have resulted in elimination of potentialPCB source areas and releases of PCBs from the facility. These activities are directly relevant tothis FS because they represent remedial measures already undertaken by Alcoa to reduce,remove, or control PCB releases from the facility. As an example of the important outcome ofthese measures, there have been no detectable concentrations of PCBs in the facility dischargesince 1992. As noted previously, these measures, along with natural processes, have resulted insubstantial reductions in sediment and fish tissue PCB concentrations in MRP 15. As a result,potential risks associated with PCBs to human health are about the same as those associated withbackground exposures. Remedial activities that have been undertaken by Alcoa are discussedbelow.

2.1 WASTE OIL LAGOON

From 1956 to 1979, Alcoa operated a 14-acre unlined waste oil lagoon, located approximately200 feet northwest of MRP 15 between the current Outfalls 003 and 004. This lagoon was closedin 1981 following removal of all pumpable oil and sludge and solidification of the remainingwaste with cement kiln dust. Following solidification of the residual waste in the lagoon,groundwater monitoring indicated that PCBs were present in the aquifers beneath theimpoundment. An oil recovery trench was installed in 1985 to prevent oil release from theimpoundment. In addition, the solidified lagoon was covered with a compacted clay cap. Alcoahas implemented a groundwater monitoring program under the Resource Conservation andRecovery Act (RCRA) and has conducted a risk assessment to evaluate the effect ofimpoundment contaminants on human health and the environment (Geraghty & Miller, Inc.1990).

2.2 TRANSFORMER PITS

Several PCB-contaminated plant transformer substations were located throughout the facility andevery Outfall and Wetland could potentially have received surface water or groundwater flowfrom them. During the late 1980s and early 1990s, Alcoa cleaned all transformer pits andeliminated all drains from the pits to the outfalls. Alcoa has removed the oil from thecontaminated transformers and implemented a monitoring program for residual levels of PCBs intransformer oils.

2.3 INDUSTRIAL SEWERS

Alcoa cleaned equipment sump pits throughout the plant and repiped them from the storm sewersystem to the industrial waste system. PCB-contaminated sediment was also removed from theindustrial waste sewer system.

2.4 FACILITY WATER RECLAMATION SYSTEM

In 1997 the facility's water reclamation system went on line. As a result, Outfall 006 no longerdischarges to the river. At one time Outfall 006 was the primary discharge location and also hadthe highest sediment PCB concentrations. With this new system in operation, wastewaterdischarge volumes were significantly reduced, and only chemically treated, sand and carbon-


SECTIOHTWO Site Remedial Activities

filtered water is discharged to the river. The only exception to this is during periods of largestorm events when excess rainwater reaches the river via the six facility outfalls.

2.5 OUTFALL 006

The lower 200 feet of Outfall 006 was dredged in 1999 and 230 cubic yards of sediment wasremoved. Outfall 006 had the highest PCB concentrations among all the six facility outfalls.

2.6 OUTFALL 002/WETLAND 2

A non-time-critical removal action was conducted in Outfall 002 and Wetland 2 during the firstQuarter of 2003. About 250 cubic yards of sediment containing PCBs and PAHs were removedfrom Outfall 002. A high-density polyethylene liner was then installed with a 10-in. concretemattress. Wetland 2 was covered with a 2- to 3-ft layer of clean fill to eliminate pathwaysassociated with exposure to PCBs and PAHs in sediments. Offsite wetlands were created incooperation with the Iowa Department of Natural Resources to mitigate the loss of the onsitewetland.

2.7 GROUNDWATER CONTAINMENT

A groundwater pump and treat system operates to contain and treat onsite groundwater. Thesystem creates a cone of depression that prevents offsite migration of contaminated groundwater.Continuous pump and treat has been in operation at the facility since 1992. Effluent from thetreatment system is monitored under the state's NPDES program.

2.8 LIGHT BULB DISPOSAL AREA

This site lies immediately adjacent to the MRP 15. Surface debris and surface soils containingPCBs and mercury was excavated and disposed in a Toxic Substances Control Act (TSCA)landfill. Post cleanup samples showed insignificant contaminant levels remaining over the 1-acre site. The site was covered with clean fill and seeded in 2001.


SECTION! H R E E Remedial Action Objectives

3.1 SCOPE AND PURPOSE

The goals of remedial action in MRP 15 at the Alcoa-Davenport site are to maintain the ecologicalintegrity of relevant ecological receptors and to minimize potential human exposures abovebackground levels or acceptable risk thresholds greater than background. This will be a focused FSbecause no significant risks above background were identified. Evaluation of various physicalactions will be limited to remedial activities that have already been undertaken by Alcoa.

3.2 EXISTING INSTITUTIONAL CONTROLS

There are existing institutional controls in place at the Alcoa facility to control the handling anddisposal of materials/wastes containing PCBs. A digging permit program at the facility requiresthat any digging that may occur is controlled. If digging is conducted in an area suspected tocontain PCBs, analyses can be conducted on waste soils for proper disposition. In addition, anymajor projects at the facility are subject to Project Environmental Health and Safety Review(PEHSR). This ensures that any major activities go through an intensive environmental reviewprior to implementation.

3.3 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS

Applicable or Relevant and Appropriate Requirements (ARARs) include substantive provisionsof any promulgated Federal or more stringent State environmental standards, requirements,criteria, or limitations that are determined to be legally applicable or relevant and appropriaterequirements for a remedial actions conducted under CERCLA. Additionally, other advisories,criteria, or guidance may be considered in determining remedies (so called to-be-considered(TBC) guidance categories. ARARs are typically divided into three groups: (1) chemical-specific, (2) action-specific, and (3) location-specific.

3.3.1 Chemical-Specific ARARsChemical-specific ARARs are typically health-based numerical criteria that are used to establishacceptable concentrations or amounts of a chemical that may be discharged to or present in theenvironment.

3.3.2 Action-Specific ARARs

Action-specific ARARs are requirements that pertain to the particular remedial alternativesconsidered for the site.

3.3.3 Location-Specific ARARs

Location-specific ARARs include restrictions placed on the conduct of activities solely becausethey occur in special locations such as wetlands, floodplains, historic properties, or criticalhabitat.

A comprehensive list of site-specific ARARs/TBC will be identified and compiled in the FS.


SECTIONFOUR Remedial Alternatives to DC Studied

Remedial alternatives to be studied include the "No Action" alternative, No Further Action withMonitoring (Natural Attenuation), and Physical Action. Each of these is briefly discussed in thisWork Plan.

4.1 NO FURTHER ACTION

The No Further Action alternative will be evaluated to assess what impacts, if any, would occurin the event that no remedial action was taken beyond those activities already implemented byAlcoa. As discussed in Section 2, previous and ongoing remedial activities that have beenundertaken by Alcoa include:

• Closure of the Waste Oil Lagoon• Cleaning transformer pits and sewer lines• Wastewater recycle and carbon treatment of the discharge• Groundwater containment• Maintenance activities at the Light Bulb Disposal Area• Removal actions in Outfall 002 and Wetland 2.• Sediment removal and weir relocation in Outfall 006

This alternative provides a baseline to evaluate the effectiveness of remaining alternatives andmay be the most appropriate alternative. This alternative will not consider the effects of naturalattenuation.

Institutional controls already in place at the Alcoa facility (Section 3.2) would be maintainedunder the No Action alternative. Institutional controls are designed to enhance the effectivenessof an alternative and, therefore, may also be combined with other alternatives underconsideration.

4.2 NO FURTHER ACTION WITH MONITORING

No Further Action with Monitoring is a remedial alternative that reduces the concentrations ofchemicals by natural processes including advection, dispersion and bioattenuation. As discussedin Section 4.1, it recognizes the remedial activities already undertaken by Alcoa, and institutionalcontrols already in place at the Alcoa facility would be maintained. No further action withmonitoring is an appropriate remedial method where it is protective of human health and theenvironment, and will be capable of achieving site-specific remediation objectives.


SECTIONFIVE Approach to Evaluating Remedial Alternatives

A remedial alternative may include one or more corrective measures to achieve the selectedclean-up level throughout the area requiring remediation. Alternatives are typically developedusing different technologies to ensure that a range of strategies is evaluated. Alternatives forsome sites may range from no-action to complete removal and destruction. Actions alreadyundertaken at Alcoa include removal (e.g., surface soils containing PCBs were removed from theLight Bulb Disposal Area) and containment (e.g., solidification of wastes in the Waste DisposalLagoon).

Further remedial action associated with physical action in the river may include removal ofcontaminated sediment through dredging; or isolation of contaminated sediments throughcapping or covering. For MRP 15, however, further actions are not warranted and will not beevaluated as a remedial alternative. The investigative results did not identify a significant sourceof contaminated sediments that require removal or capping. The human health and ecologicalrisk assessments associated with the river demonstrated that risks are principally associated withelevated fish tissue concentrations and residual risks are equivalent to the reference areas forhuman health. Similarly, the principle pathway evaluated in the ecological assessment wasbioaccumulation into biota; however, the results concluded no significant ecological risks.Therefore, given that residual contaminants within river sediments pose low risk, the greaterconcern for this feasibility study is the potential for recontamination of river media (sediment,water, biota) as a result of future releases from the Alcoa facility.

5.1 GENERAL APPROACH

As indicated in Section 4, remedial alternatives to be evaluated include the No Further Actionalternative, and No Further Action with Monitoring (Natural Attenuation). In accordance withthe National Oil and Hazardous Substances Pollution Contingency Plan, these alternatives willbe evaluated in the context of effectiveness, implementability, and cost (40 CFR §300.430(f)).Each is discussed in the following text.

Effectiveness "focuses on the degree to which an alternative reduces toxicity, mobility, orvolume through treatment, minimizes residual risks and affords long-term protection, complieswith ARARs, minimizes short-term impacts, and how quickly it achieves protection.Alternatives providing significantly less effectiveness than other, more promising alternativesmay be eliminated" (40 CFR §300.430(e)(7)(i)).

Issues that will be discussed in the evaluation of effectiveness will include: 1) the potentialeffectiveness of process options in handling the estimated areas or volumes of media andmeeting the remediation goals identified in the remedial action objectives; 2) the potentialimpacts to human health and the environment during construction and implementation; and 3)how proven and reliable the process is with respect to the contaminants and conditions at the site(USEPA 1988). For remedial activities that have already been implemented by Alcoa, theeffectiveness evaluation will include a discussion of issues such as volume of material removed,or reduction in contaminant exposures following the activity.

Implementability is the criterion which "focuses on the technical feasibility and availability ofthe technologies each alternative would employ, and the administrative feasibility ofimplementing the alternative. Alternatives that are technically or administratively infeasible or


SECTIONFIVE Approach to Evaluating Remedial Alternatives

that would require equipment, specialists, or facilities that are not available within a reasonableperiod of time maybe eliminated from further consideration" (40 CFR §300.430(e)(7)(ii)).

An alternative is implementable if the alternative is both technically and administrativelyfeasible. Technical implementability is used to screen out process options that are clearlyineffective or unworkable at a site. Administrative feasibility refers to the ability to obtain thenecessary permits and approvals from other regulatory offices and agencies, the availability oftreatment, storage, and disposal facilities, and the availability of necessary equipment and skilledworkers to implement the technology, hi the context of remedial activities that have alreadybeen implemented by Alcoa, the activity is implementable in the sense that the activity isoccurring or has already occurred. However, implementability will also be discussed in thecontext of feasibility of continuing operations and maintenance of ongoing activities such asgroundwater pump and treat and water reclamation.

Cost provides that "the costs of construction and any long-term costs to operate and maintain thealternatives shall be considered. Costs that are grossly excessive compared to the overalleffectiveness of alternatives shall be considered as one of several factors used to eliminatealternatives. Alternatives providing effectiveness and implementability similar to that of anotheralternative by employing similar methods of treatment or engineering control, but at a greatercost, maybe eliminated" (40 CFR §300.430(e)(7)(iii)).

"Cost analysis is made on the basis of engineering judgment, and each process is evaluated as towhether costs are high, low or medium relative to other process options in the same technologytype" (USEPA 1988).

Alternatives that do not protect human health and the environment, do not meet ARARs, areineffective or unworkable at the site, or are significantly more costly than other potentiallyapplicable alternatives will be screened from further consideration. The following sectionssummarize screening criteria to be applied to the corrective measures for the site.

5.2 COMPARATIVE ANALYSIS OF ALTERNATIVESA comparative analysis of the alternatives will be performed on those alternatives determined tobe protective of human health, environmentally effective, and technically and economicallyfeasible. The comparison will include descriptions of the alternatives including a detailedevaluation and comparison of each alternative. The following factors will be highlighted:

• Reduction of Toxicity, Mobility, and/or Volume,

• Short- and Long-term Effectiveness/Reliability,

• Implementability, and

• Cost.

Based on the comparative analysis of remedial action alternatives, a set of conclusions andrecommendations will be prepared, which provides a brief discussion of the factors thatdistinguish each option and recommends the most suitable remedial option for the site.


SECTIONS IX References

Geraghty and Miller. 1990. Final Groundwater Assessment for the ALCOA-Davenport WasteSite. February 1990.

Geraghty and Miller. 1992. Initial Facility Site Assessment Report, Alcoa-Davenport Works,Riverdale, Iowa. Prepared by Geraghty & Miller, Inc., for Alcoa. April 15, 1992.

JEG. 1994. Preliminary Identification of Contaminants of Concern Rationale for the MississippiRiver Pool 15. Prepared for U.S. Environmental Protection Agency, Region VII byJacobs Engineering Group Inc., Lenaxa, Kansas.

URS. 2002. Ecological Risk Assessment Report, Mississippi River Pool 15, 2000. Prepared forAlcoa Davenport Works, Davenport, Iowa, by URS Corporation, Franklin, Tennessee.

URSGWC. 1999. Evaluation of Biennial Fish Investigations, Mississippi River Pool 15.Prepared for Alcoa-Davenport Works by URS Greiner Woodward-Clyde, Franklin, TN.

URSGWC. 2000a. Human Health Risk Assessment Report, Mississippi River Pool 15. Preparedfor Alcoa-Davenport Works by URS Greiner, Woodward-Clyde, Franklin, TN.

URSGWC. 2000b. Ecological Problem Formulation Memorandum, Mississippi River Pool 15,2000. Prepared for Alcoa Davenport Works, Davenport, Iowa, by URS GreinerWoodward Clyde, Franklin, Tennessee.

USCOE. 1984. Chemical analyses of sediments and mussel tissue, Pool 15 Upper MississippiRiver. Prepared by Brice, Petrides - Donohue, of Waterloo and Des Moines, Iowa, forthe U.S. Army Corps of Engineers, Rock Island District, Rock Island, Illinois.[Sometimes referred to as the BPD Report.]

USEPA. 1983. PCB Contamination in Mississippi River Pool 15, Davenport, Iowa. UnitedStates Environmental Protection Agency, Office of Enforcement and ComplianceMonitoring, National Enforcement Investigations Center, Denver, Colorado.[Mimeographed report.]

USEPA. 1988. Guidance for Conducting Remedial Investigations and Feasibility Studies UnderCERCLA. United States Environmental Protection Agency Office of Emergency andRemedial Response, October 1988, EPA/540/G-89/004, OSWER Directive No. 9355.3-01

WCC. 1993. Onsite Sediment Sampling Results Phase IA-SIS, Alcoa-Davenport Facility.Prepared for Alcoa Davenport Works, Davenport, Iowa, by Woodward-ClydeConsultants, Franklin, Tennessee.

WCC. 1994. Sediment/Soil Investigation Studies: Phase II. Delineation of Critical Study Areas.Prepared for Alcoa Davenport Works, Davenport, Iowa, by Woodward-ClydeConsultants, Franklin, Tennessee.


SECTIONS IX References

WCC. 1996a. Sediment and Water Sampling Results, Phase III, Alcoa-Davenport Facility.Prepared for Alcoa Davenport Works, Davenport, Iowa, by Woodward-ClydeConsultants, Franklin, Tennessee. March 1996 Draft.

WCC. 1996b. Supplemental Field Investigations in Support of Risk Assessment ActivitiesMississippi River Pool 15. Prepared for Alcoa Davenport Works, Davenport, Iowa, byWoodward-Clyde Consultants, Franklin, Tennessee. August 1996.

WCIA. 1997. Supplemental Field Investigations in Support of Risk Assessment ActivitiesMississippi River Pool 15. Prepared for Alcoa Davenport Works, Davenport, Iowa, byWoodward-Clyde International-Americas, Franklin, Tennessee. May 1997.

WCIA. 1998a. Chemicals of Potential Concern and Chemicals of Potential Ecological ConcernMemorandum, Alcoa-Davenport Facility. Prepared for Alcoa Davenport Works,Davenport, Iowa, by Woodward-Clyde Consultants, Franklin, Tennessee.

WCIA. 1998b. Human Heath Exposure Assessment Memorandum Mississippi River Pool 15Prepared for Alcoa-Davenport Works by Woodward-Clyde International-Americas,Franklin, TN.

YMA. 1990. Summary of Near-Field Sediment Studies-Mississippi River Pool 15. Preparedfor Alcoa Davenport Works, Davenport, Iowa by Young-Morgan & Associates, Franklin,Tennessee.

YMA. 1991. A Sediment/Soil Investigation Studies Work Plan. Prepared for Alcoa DavenportWorks, Davenport, Iowa by Young-Morgan & Associates, Franklin, Tennessee.


site: /mrp break- other: urs(1990 aoc) with the usepa region vii, under section 106(a) of cercla, as...

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