technical analysis of baseline ecological risk assessment and prap for mercury in onondaga lake

7/31/2019 Technical Analysis of Baseline Ecological Risk Assessment and PRAP for Mercury in Onondaga Lake

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Technical Analysis of BaselineEcological Risk Assessmentand Proposed Remedial Action Planfor Mercury in Onondaga Lake Final

Prepared for:

The Onondaga Nation Nedrow, NY 13120

Prepared by:

Stratus Consulting Inc.PO Box 4059Boulder, CO 80306-4059(303) 381-8000

Report Number 5-BD-***-

June 28, 2005 SC10653

Stratus Consulting


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Contents

List of Figures ...............................................................................................................................vList of Tables ............................................................................................................................. viiList of Acronyms and Abbreviations ........................................................................................ix

Executive Summary ................................................................................................................. S-1

Chapter 1 Introduction ...................................................................................................... 1-1

1.1 Background and Purpose of Report ................................................................... 1-1

1.2 Site Description and History.............................................................................. 1-21.3 Organization of Report ...................................................................................... 1-5

Chapter 2 The Evaluation of Ecological Risks in Sediments is NotSufficiently Protective ...................................................................................... 2-1

2.1 The Evaluation of Sediment Toxicity Studies Excluded ImportantData and Literature ............................................................................................ 2-2

2.2 The Methods Used to Develop SECs Include Only a Subset of RelevantToxicity Metrics................................................................................................. 2-3

2.3 The Methods Used to Develop PECs Include Inappropriate SECs and

Geometric Means Leading to Artificially High (Less Protective) PECs........... 2-52.4 The Methods Used to Develop PECQs Include InappropriateAveraging, Likely Leading to Artificially Low (Less Protective)Average PECQs ................................................................................................. 2-7

2.5 Explanation for Why Risk Averaging to Develop Mean PECQsis Inappropriate .................................................................................................. 2-9

2.6 Additional Issues Related to the Calculation and Use of SECs, PECs,and PECQs ....................................................................................................... 2-102.6.1 Chronic toxicity ................................................................................... 2-102.6.2 Evaluation of surface sediments only .................................................. 2-112.6.3 Reference sites ..................................................................................... 2-12

Chapter 3 The Evaluation of Bioaccumulation in Onondaga Lake Fish is NotSufficiently Protective ...................................................................................... 3-1

3.1 The Onondaga Lake Fish Community Has Been Degraded and Fish AreUnsafe to Eat because of Contamination ........................................................... 3-2

3.2 Mercury Moves throughout Onondaga Lake..................................................... 3-23.3 Evaluation of Surface Sediments, Only, Leads to Under-Protectiveness.......... 3-3

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Stratus Consulting Contents (Final, 6/28/2005)

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3.4 The Calculation of Biota-Sediment Accumulation Factors IncludesInappropriate Averaging and Extrapolations..................................................... 3-33.4.1 Problems with averaging contaminant concentrations in fish based

on size alone........................................................................................... 3-43.4.2 Problems with extrapolation of fillet concentrations to whole

body concentrations ............................................................................... 3-43.5 The Mercury BSQV is Based on Low Effect Levels Rather than No

Effect Levels ...................................................................................................... 3-53.6 BSQVs Were Not Developed for Critical Bioaccumulative Substances

Other than Mercury............................................................................................ 3-6

Chapter 4 A More Thorough and Protective Risk Assessment Justifies MoreDredging than the Preferred Alternative ...................................................... 4-1

4.1 The Remediation Objectives Are Elimination or Reduction of PotentialHealth and Environmental Impacts.................................................................... 4-1

4.2 PECQs Are Used to Evaluate Remedial Alternatives ....................................... 4-14.3 Summary of the Main Features of the Different Remediation Alternatives...... 4-24.4 Summary of the Preferred Remedy.................................................................... 4-34.5 The Preferred Remedy is Not Sufficient............................................................ 4-3

Chapter 5 Residual Risk Calculations Must be Improved Before RemedialAlternatives Are Compared ............................................................................ 5-1

5.1 Reductions in Contaminant Loadings................................................................ 5-2

5.2 Aeration of Hypolimnion................................................................................... 5-25.3 Sediment Remediation ....................................................................................... 5-35.3.1 Effectiveness of isolation capping ......................................................... 5-3

5.4 Mercury Mass Balance ...................................................................................... 5-45.5 Chronic Toxicity ................................................................................................ 5-45.6 Uncertainty Analysis and Sensitivity Analysis.................................................. 5-5

5.6.1 Uncertainty analysis............................................................................... 5-55.6.2 Sensitivity analysis ................................................................................ 5-5

5.7 Failure to Consider All Potential Risk Drivers.................................................. 5-65.8 High Residual Levels of Numerous Chemicals ................................................. 5-6

Chapter 6 Summary and Recommendations ................................................................... 6-1References .................................................................................................................................R-1


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Figures

1.1 Onondaga Lake eight sediment management units ....................................................... 1-4

2.1 Conceptual diagram illustrating conceptual groupings of sediment effects tothresholds adopted in the Onondaga Lake RI................................................................ 2-4

2.2 Maximum total mercury concentrations in 1992 in Onondaga Lake by depth ........... 2-11

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Tables

2.1 Site-specific sediment effect concentrations for mercury in Onondaga Lake based on 1992 acute toxicity data .................................................................................. 2-4

2.2 Site-specific sediment effect concentrations for mercury in Onondaga Lake based on 2000 chronic toxicity data .............................................................................. 2-5

2.3 SEC and PEC results for total mercury in Onondaga Lake sediments comparedto the mercury PEC in MacDonald et al. (2000) ........................................................... 2-5

3.1 Mercury BSAFs calculated for Onondaga Lake............................................................ 3-43.2 Target fish tissue and sediment concentrations for mercury in Onondaga Lake

expressed as NOAEL and LOAEL values for different ecological receptors asderived in the FS ............................................................................................................ 3-6

4.1 Comparison by the NYSDEC of the remedial alternatives presented in the PRAP ...... 4-44.2 Residual concentrations and hazard quotients left behind by the

preferred alternative....................................................................................................... 4-5

5.1 Concentrations in Onondaga Lake fish of contaminants considered risk driversand calculated target concentration to avoid risk .......................................................... 5-7

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Acronyms and Abbreviations

AET apparent effects thresholdAVS acid-volatile sulfide

BERA Baseline Ecological Risk AssessmentBSAF biota-sediment accumulation factorsBSQV bioaccumulation-based sediment quality valueBTEX benzene, toluene, ethylbenzene, and xylenes

cm centimeter

COC contaminants of concernCPOI chemical parameter of interestcy cubic yards

dw dry weight

EEC extreme effect concentrationER-L effects range-lowER-M effects range-median

FS Feasibility Study

HHRA Human Health Risk Assessment

km kilometer km 2 square kilometer

ILWD in-lake waste deposit

LOAEL lowest observed adverse effect level

m meter

MEC mid-range effect concentrationMNR monitored natural recovery

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Stratus Consulting Acronyms and Abbreviations (Final, 6/28/2005)

Page xSC10653

NAPLs non-aqueous phase liquids NCP National Oil and Hazardous Substances Pollution Contingency Plan NOAEL no observed adverse effect level NYSDEC New York State Department of Environmental Conservation

PAHs polycyclic aromatic hydrocarbonsPCBs polychlorinated biphenylsPCDDs polychlorinated dibenzo- p -dioxinsPCDFs polychlorinated dibenzofuransPECs probable effects concentrationsPECQs PEC quotientsPEL probable effect level

ppm parts per millionPRAP Proposed Remedial Action Plan

RI Remedial InvestigationROD record of decision

SCA sediment consolidation areaSECs sediment effects concentrationsSEDQUAL Sediment Quality Information SystemSMUs sediment management unitsSQGs sediment quality guidelines

TEC threshold effect concentrationTEL threshold effect levelTOC total organic carbon

ww wet weight


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Stratus Consulting Executive Summary (Final, 6/28/2005)

Averaging risks between contaminants, thereby masking any high levels of risk posed by individual contaminants and likely resulting in artificially low risk calculations.

The evaluation of bioaccumulation of contaminants in Onondaga Lake fish is notsufficiently protective because:

The evaluation was too limited to surface sediments, not accounting for relevanthigh levels of contamination in deeper sediments, thereby leading tounderestimation of risks

The calculation of sediment-biota accumulation factors includes inappropriateaveraging and extrapolations

The target level for post-cleanup mercury concentrations is based on sedimenttoxicity only, not the more protective level based on bioaccumulation

Bioaccumulation of other critical contaminants, including PCBs,hexachlorobenzene, and PCDD/PCDFs, all of which are proven to bioaccumulate,was not included in the analysis.

The preferred remedy calls for dredging of some highly contaminated sediments, butleaves behind other highly contaminated sediments. Under the preferred alternative:

benzene will be left at 1,387x of the purported safe level calculated by the PRAP;chlorobenzene 266x; dichlorobenzenes 377x; naphthalene 22,435x; xylenes 253x;ethylbenzene 9,403x; toluene 62,524x; and mercury 1,329x. These highly contaminatedsediments are proposed for capping even though the dredging equipment will already bein place and functioning when these sediments are left behind under the preferredalternative. Furthermore, the justification for dredging instead of capping applies to thesesediments as much as the other sediments that will be dredged under the preferredalternative. The residual contaminant levels left in place under the preferred remedy arethemselves high enough to justify remedial action at most other sites.

Capping, as described in the preferred alternative, will foreclose many opportunities toredesign, change, or improve the remedy if the cleanup does not eliminate risks as thePRAP assumes.

The PRAP fails to identify real-life goals for the preferred remedy, such as when fishfrom Onondaga Lake will again be edible, or when it will be safe to swim in the lakeagain. Given the large number of calculations that underestimate risk, describedthroughout these comments, the PRAP should include a much better program for monitoring success and requiring remedial efforts to continue until success is reached,

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Stratus Consulting Executive Summary (Final, 6/28/2005)

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particularly given the tremendous uncertainties of predicting long-term cap effectiveness.Furthermore, planning now to cease dredging operations while very high concentrationsof contaminants remain just below the last dredge cut is a risky strategy that does notappear to be rooted in scientific analysis or good public policy.

Based on this review, it is our opinion that the PRAP should be revised before a ROD is issued.As currently drafted, the PRAP contains risk calculations that include multiple levels of bias thatfail to adequately protect human health and the environment. The comparison of alternatives thatmade Alternative 4 the preferred alternative is based on the biased risk assessment. Correctingthe risk assessment will justify additional dredging and less reliance on capping than proposed byAlternative 4.


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1. Introduction1.1 Background and Purpose of Report

The Onondaga Nation retained Stratus Consulting on April 15, 2005 to review key documentsrelated to the cleanup of Onondaga Lake before the New York State Department of Environmental Conservation (NYSDEC) issues a record of decision (ROD) that will select aremedial alternative for Onondaga Lake proper. That ROD is currently scheduled for finalizationon July 1, 2005, and submittal to the U.S. District Court for the Northern District of New York.

This report provides technical analysis of, and comments on, the following key reports:Onondaga Lake Baseline Ecological Risk Assessment (BERA; TAMS, 2002a), Remedial

Investigation (RI; TAMS, 2002c), Feasibility Study (FS; Parsons, 2004), and the ProposedRemedial Action Plan for addressing risks (NYSDEC, 2004). These documents were produced

pursuant to a March 16, 1992 judicial consent decree (subsequently amended) between NYSDEC and Honeywell (formerly AlliedSignal).

There has not been sufficient time to acquire and review many of the relevant documents produced by Honeywell or NYSDEC, including all of the documents for operable units or connected sites other than Onondaga Lake itself, all of the previous documents and commentsfor Onondaga Lake proper, and most of the underlying original data for the current OnondagaLake RI, FS, BERA, Human Health Risk Assessment (HHRA; TAMS, 2002b), and ProposedRemedial Action Plan (PRAP). Furthermore, NYSDEC disapproved Honeywells 1998 and 2001

RI, BERA, and HHRA submittals (State of New York and Thomas C. Jorling v. Allied-Signal,Inc., 2002), creating a lengthy documentary history of data, reports, and comments, which is notcurrently available to Stratus Consulting.

To ensure that our review of critical data and reports was completed before the July 1, 2005ROD deadline, we have restricted this analysis to issues related to risk assessment, particularlyecological risk assessment, and more particularly emphasizing mercury risk assessment, as

presented in the most recent RI, BERA, FS, and PRAP. We have not attempted to review theunderlying data or literature, nor the previous documents and comments that led to the currentversions of these documents. These comments should be viewed as an opening for discussionsabout critical issues related to the risk assessment, and required risk management at the site.

Although we identify several technical issues of concern in the BERA, FS, and PRAP, we havefocused most of our review on three primary issues of obvious, immediate importance in theBERA, FS, and PRAP:

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Stratus Consulting Introduction (Final, 6/28/2005)

A series of evaluations led to cleanup numbers that were biased toward under-protectionSelection of remedial alternatives was based on reliance on the biased cleanup numbers,as well as inappropriate reliance on capping, particularly of highly toxic sediments thatcould be dredged with equipment already in place, which will foreclose future options totest and improve the remedyResidual risk under the preferred alternative is underestimated.

1.2 Site Description and History

Onondaga Lake is a 12-square kilometer (km 2) lake northwest of the city of Syracuse in central New York State (TAMS, 2002c). The lake is about 7.2 kilometer (km) long and 1.6 km wide,with an average water depth of 11 meters (m). The eastern shore of the lake is primarily urbanand residential, while the northern shore is mostly parkland, wooded areas, and wetlands.

The lake has two deep basins, a northern basin and a southern basin, with maximum depths of 19and 20 m, respectively (TAMS, 2002c). A saddle region at a depth of about 17 m divides the two

basins. Most of the lake has a broad nearshore shelf with depths less than 3.7 m. The two largesttributaries to the lake are Ninemile Creek and Onondaga Creek. In addition to tributaries to thelake, treated effluent from the Onondaga County Metropolitan Wastewater Treatment Plant

provides about 19% of the water entering the lake.

From 1884 to 1986, Allied Chemical and AlliedSignal (now Honeywell) operated chemical production facilities on the southwest side of the lake (TAMS, 2002c). These operations,collectively known as the Syracuse Works, used the regions natural salt brines and limestone to

produce four major product lines:

Soda ash and related productsBenzene, toluene, ethylbenzene, and xylenes (collectively known as BTEX), and tar

products from the recovery of coal distillation (coking) byproductsChlorinated benzenes and the byproduct hydrochloric acid from the chlorination of

benzeneChlor-alkali products (e.g., chlorine, caustic potash).

The main releases of contaminants resulting from manufacturing processes were mercury,organic contaminants, and calcite-related contaminants (TAMS, 2002c). The main organiccontaminant releases were of BTEX compounds; chlorinated benzenes; polycyclic aromatichydrocarbons (PAHs), especially naphthalene; polychlorinated biphenyls (PCBs); and

polychlorinated dibenzodioxins/polychlorinated dibenzofurans (PCDD/PCDFs). Mercury,mostly from chlor-alkali plants that used mercury in the production of chlorine and caustic soda,is the primary contaminant of concern (NYSDEC, 2004).

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Onondaga Lake is a sink for contaminants. For every chemical parameter of interest (CPOI)examined, estimated loads of contaminants entering the lake are at least five times greater thanloads leaving the lake (U.S. EPA, 2005). Manufacturing wastes were discharged from three

plants to four main waste disposal sites: the Semet Residue Ponds, Geddes Brook and NinemileCreek, the Solvay wastebeds, and directly into the lake (TAMS, 2002c). Wastes dischargeddirectly to the lake through the East Flume tributary resulted in the formation of a large in-lakewaste deposit (ILWD) that extends about 610 m into the lake and 1,219 m along the lakeshore.The ILWD contains waste up to 13.7 m thick (TAMS, 2002c).

In 1992, Honeywell entered into a consent decree with the state of New York to conduct a RIand FS for Onondaga Lake. The RI was conducted by Honeywell from 1992 to 2000, withadditional work by NYSDEC in 2001. Two drafts of the RI prepared by Honeywell were rejectedon technical grounds by NYSDEC (State of New York and Thomas C. Jorling v. Allied-Signal,Inc., 2002). The final RI was completed by TAMS Consultants, Inc. with assistance from

NYSDEC in December 2002 (TAMS, 2002c). The FS, completed in November 2004, evaluateda range of potential remedial technologies and alternatives to develop a recommended remedyfor chemicals found to pose ecological or human health risks (Parsons, 2004).

The FS divided Onondaga Lake into eight sediment management units (SMUs) based onlocation, water depth, contaminant type, and other physical characteristics (Parsons, 2004; seeFigure 1.1). Sediment located above the lakes seasonal thermocline, which occurs at a depth of about 9 m during thermal stratification in summer, was defined as nearshore (littoral) sediment.Sediment below the thermocline was defined as profundal sediment (Parsons, 2004). Thesedesignations were made to distinguish between the epilimnion and hypolimnion, which havedifferent biological, physical, and chemical processes. The epilimnion is the warm, upper layer

of circulating water during summer stratification of the lake. The hypolimnion is the cooler,noncirculating water below the thermocline. Organic and inorganic solids from the epilimnionsettle by gravity toward the lake bottom. Over the summer, biodegradation of the organic solidsdepletes the oxygen in the hypolimnion, sometimes creating depleted, hypoxic, or anoxicconditions. It is thought that the primary source of methylmercury to the water column is themethylation of mercury in the hypolimnion during summer when conditions in the hypolimnionare anoxic (NYSDEC, 2004).

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SMU 1SMU 2

SMU 3SMU 4

SMU 5

SMU 6

SMU 7

NSMU 8

SOLVAY

Harbor Brook

Figure 1.1. Onondaga Lake eight sediment management units.

SMUs 1 through 7 include littoral areas that extend from the lakeshore to a depth of 9 m. TheseSMUs are:

SMU 1: ILWDSMU 2: CausewaySMU 3: Wastebeds 1 through 8SMU 4: Mouth of Ninemile Creek SMU 5: Northern Shore

SMU 6: Ley Creek to 700 feet south of Onondaga LakeSMU 7: 700 feet south of Onondaga Creek to the ILWD.

SMU 8, the Profundal area, encompasses the lake bottom in the deeper parts of the lake at depthsgreater than 9 m (Parsons, 2004).

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1.3 Organization of Report

The remainder of this report is organized as follows:

Chapter 2 reviews the sediment toxicity analysisChapter 3 reviews the evaluation of the bioaccumulation of contaminants in fishChapter 4 discusses proposed alternatives for remediation and the preferred remedyChapter 5 discusses residual risksChapter 6 presents a summary of major findings and recommendations for next steps.


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2. The Evaluation of Ecological Risks inSediments is Not Sufficiently Protective

This chapter discusses methods used in the BERA (TAMS, 2002a), the RI (TAMS, 2002c), theFS (Parsons, 2004), and the PRAP (NYSDEC, 2004) to calculate ecological risks associated withdirect toxicity to benthic organisms in lake sediments, which currently captures most of the risk calculations in the BERA and applies to sediment remedial decisions throughout LakeOnondaga. We would like to discuss with the response agencies whether we have accuratelyinterpreted their evaluation of sediment toxicity and its use in risk calculations, before offeringdetailed comments on potential improvements to the methodologies, or incorporation of additional information from the literature.

Based on our initial review of the documents listed above, our primary comments regarding theevaluation of sediment toxicity include:

The evaluation of risk to benthic organisms was based only on acute toxicity in one site-specific study. Additional site-specific data are available, however, including data onchronic toxicity. In addition, toxicity literature is available for many of the chemicalsfound in Lake Onondaga sediments. These additional sources of information should beused to derive robust PECs and PECQs that can be applied independently to lakesediments. This evaluation is likely to lead to a more protective risk assessment andremedial decisions.

The methods used to develop PECs included sediment effects concentrations (SECs) thatrepresent concentrations that always cause toxicity. This is inappropriate because

protective thresholds like PECs should eliminate toxicity. Furthermore, PECs are basedon an inappropriate series of geometric means of different SECs. Combined, these two

problems lead to PECs that are numerically higher and less protective of human healthand the environment.

Rather than deriving PECs and PECQs for each chemical, based on all of the site-specificdata and relevant literature, PECQs are averaged within and between chemical classes.This averaging likely reduces the protectiveness of the resultant average PECQs, andcertainly obscures whether single chemicals are driving the true risk in any givensediment sample.

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Stratus Consulting Ecological Risks: Sediments (Final, 6/28/2005)

2.1 The Evaluation of Sediment Toxicity Studies ExcludedImportant Data and Literature

The overall objective of the Onondaga Lake sediment toxicity studies performed as part of theBERA was to evaluate the toxicity of surface sediments to sensitive and representative testspecies in relation to chemical concentrations and conventional sediment parameters, such asgrain size distribution, total organic carbon (TOC), and acid-volatile sulfide (AVS) (TAMS,2002a).

Laboratory tests of sediment toxicity used the amphipod Hyalella azteca and the chironomidChironomus tentans . The amphipod was selected to represent epibenthic macroinvertebrates andthe chironomid was intended to be representative of infaunal macroinvertebrates. Laboratorytests involved exposure of lake sediments containing contaminants of concern (COC) to

C. tentans and H. azteca , with subsequent observation of effects on growth and survival (TAMS,2002a).

In 1992, acute (short-term) sediment toxicity was evaluated at 79 sites in Onondaga Lake and atfive sites in Otisco Lake, which was used as a reference lake (TAMS, 2002c). All sites sampledfor toxicity testing in 1992 were at locations with a water depth shallower than 4.5 m. Samplingwas conducted in July and August. Toxicity tests were conducted for 10 days.

Toxicity results for 1992 from each station in Onondaga Lake were compared with only one siteat the reference lake, Otisco Lake, based on sediment type. Paired comparisons were madestatistically using the Sediment Quality Information System (SEDQUAL) program. 1 Endpointsevaluated were growth (biomass) and survival for each of the species tested. Results indicatedthat chironomids were more sensitive than amphipods and that the chironomid survival endpointwas the most sensitive endpoint [significant lethality effects (p 0.05) were seen in 35 of the79 stations].

Additional chronic sediment toxicity testing was then conducted at 15 locations in OnondagaLake in 2000 (TAMS, 2002c). Forty-two day (42 d) chronic toxicity tests were conducted onsamples collected from the top 15 centimeter (cm) of the sediment column. Toxicity endpointswere growth, survival, and reproduction for H. azteca and the chironomid C. tentans . All sitessampled in 2000 were at locations with a water depth shallower than 5 m. The same statisticalmethods were used to evaluate toxicity for the chronic tests as were used for the 1992 acute tests.As in 1992, the 2000 study found that chironomids were more sensitive than amphipods, and that

1. SEDQUAL is a computer program developed by the Washington State Department of Ecology that performs statistical comparisons among test, reference, and control samples for assessment of sedimenttoxicity.

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the chironomid survival endpoint was more sensitive than growth or reproduction [significantlethal effects (p 0.05) were seen in 9 of the 15 sites].

Results of the sediment toxicity studies were used to develop SECs, PECs, and mean PECQs, asdiscussed in the following sections.

2.2 The Methods Used to Develop SECs Include Only a Subset of Relevant Toxicity Metrics

To evaluate potential risks to benthic invertebrates resulting from exposure to COCs in surfacesediments, site-specific SECs were determined for each COC (TAMS, 2002a, 2002c). Five typesof SECs were developed for each COC:

Effects range-low (ER-L): the contaminant concentration in sediment representing thelowest 10th percentile of the values at which toxic effects on benthic invertebrates wereobserved.

Threshold effect level (TEL): the geometric mean of the lowest 15th percentile of theconcentration at which toxic effects on benthic invertebrates were observed, and the50th percentile of the concentration at which no toxic effects were observed.

Effects range-median (ER-M): the 50th percentile of concentration at which toxiceffects on benthic invertebrates were observed.

Probable effect level (PEL): the geometric mean of the ER-M and the 85th percentile of the no-effects concentrations.

Apparent effects threshold (AET): the concentration above which a particular toxiceffect in benthic invertebrates is always significant compared to reference samples.

The BERA considered these five SECs to be representative of three conceptual adverse effectsthresholds for benthic invertebrates: (1) the ER-L and TEL were considered to be sedimentconcentrations below which toxic effects are expected to rarely occur ; (2) the ER-M and PELwere considered to be sediment concentrations above which toxic effects are predicted to

frequently occur ; and (3) the AET was considered to be a threshold above which toxic effects are predicted to always occur (TAMS, 2002a; Figure 2.1).

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Sediment effectthreshold

Expectedeffect

ER-L/TEL

Rarely

ER-M/PEL

Frequently

AET

Always

Contaminantconcentration low high

Figure 2.1. Conceptual diagram illustrating conceptual groupings of sediment effectsto thresholds adopted in the Onondaga Lake RI.

Results for mercury presented in the BERA (TAMS, 2002a) illustrate the development of SECs(TAMS, 2002c). Dry weight (dw) mercury concentrations in sediment were used to develop theSECs for each toxicity endpoint from the acute 1992 study (Table 2.1) and from the chronic2000 study (Table 2.2).

The final SECs were selected from the 1992 data as follows: the final AET was the lowest of allfour AETs; the final value for the four other SECs (ER-L, ER-M, TEL, and PEL) was the value

based on chironomid survival only. The 2000 results for chronic toxicity were not incorporatedinto the final SECs because it was thought that there were insufficient data from the 2000sampling (NYSDEC, 2004).

Table 2.1. Site-specific sediment effect concentrations for mercury in Onondaga Lake basedon 1992 acute toxicity data (in mg/kg dw)Endpoint ER-L TEL ER-M PEL AET

Amphipod biomass 0.6 1.2 6 4.3 20.4

Amphipod survival 5.2 3 5.2 5.7 a

Chironomid biomass 0.8 1.3 5.2 4.1 30

Chironomid survival 0.5 b 1.0 b 2.8 b 2.8 b 13 b

a. No value calculated due to limited effects. b. Selected as final SEC.

Source: Table 9-11 of TAMS (2002a).

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Table 2.2. Site-specific sediment effect concentrations for mercury in Onondaga Lake basedon 2000 chronic toxicity data (in mg/kg dw)

Endpoint ER-L TEL ER-M PEL AETAmphipod biomass 3.2 3.4 9.4 10.1 a

Amphipod survival 0.7 1.4 9.2 7.1 9.6

Amphipod reproduction 0.7 1.4 0.7 2.8 17.2

Chironomid biomass 0.7 1.5 2.3 3.9 9.6

Chironomid survival 0.7 1.6 3.0 5.9 17.2

Chironomid reproduction 1.6 2.5 3.3 5.3 17.2

a. No value calculated due to limited effects.

Source: Table 9-12 in TAMS (2002a).

2.3 The Methods Used to Develop PECs Include InappropriateSECs and Geometric Means Leading to Artificially High (LessProtective) PECs

The five SECs for each contaminant (Table 2.3) were used to derive a PEC for a contaminant toidentify areas of the lake bottom that could pose a risk to benthos (TAMS, 2002a, 2002c). TAMS(2002a) calculated the PEC as the geometric mean of the five SEC values. The PEC was definedas the contaminant concentration in sediments above which adverse effects in benthic

invertebrates are expected to frequently occur based on the geometric mean of the five SECs for that contaminant (TAMS, 2002a).

Table 2.3. SEC and PEC results for total mercury in Onondaga Lake sediments(in mg/kg dw) compared to the mercury PEC in MacDonald et al. (2000)

Year of sediment sampling ER-L TEL ER-M PEL AET

Onondaga Lakeconsensus PEC

MacDonaldet al. (2000)

PEC a

1992 0.51 0.99 2.8 2.84 13 2.2 1.1

a. TAMS (2002a) cites Ingersoll et al. (2000), however, the original source for this PEC is MacDonald et al.(2000).

Source: 1992 toxicity test results, as presented in Table 11-8 of TAMS (2002a).

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The final SEC and PEC estimates for total mercury in sediments are presented in Table 2.3, based solely on the 1992 results for chironomid survival. Data for the other years were excludedfrom the analysis (NYSDEC, 2004). Note that the number derived in the BERA is double (less

protective than) the number derived by MacDonald et al. (2000). This is an indication that thePECs derived in the BERA should be more thoroughly evaluated, using all site-specific data andall relevant toxicity literature.

Although the general method used in the BERA (TAMS, 2002a) to develop a final PEC valueappears to be based on MacDonald et al. (2000) and Ingersoll et al. (2001), there are importantdifferences in the methodologies. MacDonald et al. (2000) compiled and screened publishedsediment quality guidelines (SQGs), based on empirical data from multiple unique sources. Theintent was to provide a unifying synthesis (consensus) of the existing guidelines that wouldreflect causal effects and account for the effects of contaminant mixtures in sediments. Further,MacDonald et al. (2000) grouped published SQGs into two categories according to their originalintent: those that attempted to identify concentrations below which no toxicity was expected(termed threshold effect concentrations, or TECs), and those that attempted to identifyconcentrations above which harmful effects were expected to occur frequently (termed probableeffect concentrations, or PECs). Separate consensus-based TEC and PEC values were thendeveloped by calculating the geometric mean of all TECs and PECs from each source,respectively. TECs were not included in the calculation of the consensus-based PEC.

In contrast, the BERA (TAMS, 2002a) developed consensus-based PECs based on the resultsof a single toxicological study. A better approach would be to evaluate all of the site-specificdata in the context of the relevant toxicity literature for each chemical. The PECs in the BERAcombine values for threshold effects (ER-L, TEL), probable effects (ER-M, PEL), and expected

effects (the AET). In addition, the BERA incorporates the AET value into the PEC calculation.MacDonald et al. (2000) did not include AET values in the calculation of PECs because they donot represent toxicity thresholds, but rather are concentrations above which harmful effectsalways occur. As shown in Tables 2.1 and 2.2, both acute and chronic tests conducted onOnondaga Lake sediments resulted in AET values higher than the thresholds above whichharmful effects are expected to occur frequently (the ER-M and the PEL). The inclusion of theAET in the calculations thus increases the resulting PEC value and reduces the protectiveness of the risk assessment. This is illustrated by the fact that the Onondaga PEC for mercury,2.2 mg/kg, is two times greater than the PEC developed by MacDonald et al. (2000; Table 2.3).

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2.4 The Methods Used to Develop PECQs Include InappropriateAveraging, Likely Leading to Artificially Low (Less Protective)Average PECQs

The Onondaga Lake FS and PRAP integrate the PECs from the BERA into a mean PECQ asfollows:

1. The concentration for each individual chemical in a sample was divided by its PEC todetermine the PECQ for that contaminant in the sample (e.g., a mercury concentration ina sample of 4.4 mg/kg divided by the mercury PEC of 2.2 mg/kg yields a PECQ of 2 for mercury in the sample). Note that the PECQ is equivalent to a hazard quotient, and valuesover 1 indicate potential risks because the concentration in the sample is higher than thecalculated toxic threshold level.

2. All CPOIs in a sample were separated into five groups, based on chemical class (metals,aromatics, chlorinated benzenes, PAHs, and PCBs), and the average PECQ for that groupwas determined [e.g., (PECQethylbenzene + PECQxylenes)/2 = Mean PECQaromatics].

3. For each sample, the chemical group mean PECQs were then averaged to yield a SamplePECQ [e.g., (Mean PECQaromatics + Mean PECQmetals + Mean PECQPAHs)/3 =Sample PECQ].

The sample PECQs were evaluated to determine the relative risk throughout the lake (NYSDEC,2004; Parsons, 2004). This approach was used in an attempt to compare the acute toxicity risk from the mixture of contaminants at the various sampling locations, and also to select a level of remediation that would address the overall risk of direct acute toxicity to the benthos fromsediment contamination.

However, each individual PECQ (equivalent to a hazard quotient) should itself be a directindication of risk. Again, a better approach would be to place all of the site-specific toxicity inthe context of the relevant toxicity literature for each chemical to derive PECs and PECQs thatcan be applied independently to lake sediments. Averaging the individual risk metrics, however,can substantially underestimate risk in the mixture, and obscures situations where specificchemicals become strong risk drivers within the mixture. In addition, when various chemicalswithin chemical classes have similar modes of toxicity and can act independently and additivelyto harm organisms in the environment, PECQs should be summed within chemical classes. Eachchemical class PECQ-sum then should be used independently to evaluate risk, pre- and post-remedy. Such procedures would ensure that the risk of each chemical is evaluated, rather than

potentially masking high-risk chemical concentrations via risk averaging.

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In the FS, NYSDEC recalculated the PECQs developed by Honeywell to include only CPOIsthat demonstrated a statistical relationship with the PECQs (23 of the original 46 CPOIs)(Parsons, 2004). This improved the predictive ability of the PECQs and reduced the amount of inappropriate risk averaging. A regression of the revised PECQs against chironomid mortalityhad an r 2 value of 0.52, as opposed to an r 2 value of 0.41 for the regression of the original PECQsagainst chironomid mortality. The final list of CPOIs used in the revised PECQs included:

BTEX (ethylbenzene and xylenes)Chlorinated benzenes (monochlorobenzene, dichlorobenzenes, and trichlorobenzenes)PAHs (all 16 individual compounds)PCBs (total PCBs)Metals (mercury).

We note that NYSDEC partially rectified the problem of risk-averaging by applying the mercury

PECQ, independently, and also calculating a bioaccumulation-based sediment quality value(BSQV) because mercury bioaccumulates (see Chapter 3 for our comments on the mercuryBSQV). However, the rationale for assessing risk independently for mercury applies equally tothe other CPOIs in Lake Onondaga, as does the rationale for calculating BSQVs to the other CPOIs that bioaccumulate, such as PCBs, dioxins, furans, and hexachlorobenzene.

Furthermore, the rationale presented in the proposed plan for limiting these independent andadditional analyses that the other chemicals are co-located with mercury and will therefore beadequately addressed is highly suspect given the levels of chemicals that would be left behindunder the preferred alternative [benzene 208 parts per million (ppm); chlorobenzene 114 ppm;dichlorobenzenes 90 ppm; naphthalene 20,573 ppm; xylene 142 ppm; ethylbenzene 1,655 ppm;

toluene 2,626 ppm; mercury 2,924 ppm] (NYSDEC, 2004). Instead, the PRAP should analyzethe residual risk of these and other chemicals that would be left in place under each alternative, particularly in light of the fact that many of the alternatives contemplate a cessation of dredgingoperations just as highly contaminated sediments are being exposed.

Finally, although the Nations comments regarding cap effectiveness are presented elsewhere,we note that these are very high levels to be left in place (see Table 4.2), calling into question therationale for a cap. If capping cannot protect human health and the environment from most highconcentrations throughout the lake where dredging will be required, how can capping be

protective for these very high residual concentrations? Furthermore, capping forecloses theopportunity to monitor remedial effectiveness and continue dredging, if needed (capping willmake subsequent dredging quite difficult and expensive, even if the cap fails).

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2.5 Explanation for Why Risk Averaging to Develop Mean PECQsis Inappropriate

A risk assessment should clearly identify the various sources of risk to human health and theenvironment, and risk management decisions should clearly explain any residual risks that resultfrom various potential remedial decisions. However, the mean PECQ approach adopted by

NYSDEC has multiple levels of risk averaging that potentially obscure the evaluation of risk inOnondaga Lake sediments. We describe the problems with each level of risk averaging used toderive PECQs below. However, the reason that risk averaging, particularly multiple levels of risk averaging, is potentially so problematic can be seen by simple analogy.

If a person wants to know whether a glass of water is safe to drink, the key issue is whether anycontaminant is present in quantities high enough to cause harm. If the water contains enough lead

to cause harm, then drinking the water is a poor choice, even if the amount of cadmium in thewater is far below the level that causes harms. If the water also contains many other metals,many PAHs, many PCBs, many dioxins and furans, and many other kinds of hazardoussubstances, as do the sediments, waters, and biota of Onondaga Lake, then a reasonable personwould want to know whether any one of the chemicals is present at levels high enough to causeharm.

Knowing something about how many different contaminants in the sediment could cause harm isalso useful, but calculating the average risk of all of the chemicals in a sample is worse thaninadequate; it is misleading. This can be seen clearly from the fact that adding more and morechemicals that happen to be present at low levels has the effect of lowering the average risk evenwhen chemicals are present at clearly harmful levels. If our hypothetical glass of water has10 times too much lead to be safe, but 10 other metals are present at 1/10th of their harmfullevels, then, on average, the metals are just at the threshold of being safe, even though the leadstill makes the water unsafe to drink. In theory, one could include hundreds of individual PCBs,dioxins, furans, PAHs, and metals at very low levels to make the glass of water seem safe,according to average risk, even if lead (or any other contaminant) concentrations were hundredsof times higher than safe levels.

Certainly, complicated sites like Onondaga Lake require a variety of techniques to summarizecomplex data and allow practical decision-making. However, risk factors for different locationswithin Onondaga Lake sediments could easily be shown as the highest hazard quotient (i.e., theratio of: contaminant concentration divided by the harmful concentration), or PECQ, for anychemical in each sediment sample, or perhaps even the sum of all hazard quotients (or PECQs)for all chemicals in a sediment sample, rather than the average hazard quotient for each sample.

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(Parsons, 2004). Because the ER-L is the concentration at which acute effects are rarelyexpected, it was thought that using the ER-L would likely protect the benthos from chronic aswell as acute effects (NYSDEC, 2004). However, the ER-L was not used for any of the other alternatives, including the preferred remedy, and no other method was used to address chronictoxicity in selecting remedial alternatives. There is no reason why chronic toxicity cannot beaddressed directly for all alternatives, using existing data from the site, and other relevant,

published literature.

It was also assumed that there would be a reduction in chronic toxicity in those areas of the lakewhere existing contaminated littoral sediments would be capped, assuming the cap is effective inkeeping levels below the PECs (NYSDEC, 2004). However, cap effectiveness is subject todebate, as discussed in Chapter 5 of this document concerning residual risks, and elsewhere inthe Nations comments.

2.6.2 Evaluation of surface sediments only

Only surface sediments less than 2 cm were evaluated, but the highest levels of somecontaminants are found at greater depths. Figure 2.2 presents maximum concentrations of mercury measured in depth segments from Onondaga Lake.

0

10

20

30

40

5060

70

80

1 2 3 4 5 6

Depth (cm)

M a x

i m u m

t o t a l m e r c u r y

( m g /

k g ) -

0-5 5-15 100-20015-30 30-100 200-300

Figure 2.2. Maximum total mercury concentrations (mg/kg) in 1992 in Onondaga Lakeby depth.

Source: Appendix G1 of the RI (TAMS, 2002c).

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In our preliminary review of the RI, BERA, FS, and PRAP, we did not identify any textaddressing this issue, and sediment mixing typically occurs throughout a greater depth than 2 cmof sediment because of bioturbation, storms and waves, propeller wash from boats, and shorelineor lake bottom construction. Furthermore, several remedial alternatives, including the preferredalternative, dredge surface sediments, potentially leave behind very high levels of contamination.Again, the rationale that capping will be effective for these deeper sediments is suspect, giventhe rationale for dredging instead of capping of the current surface sediments.

2.6.3 Reference sites

Chapter 11 of the BERA indicates that only one site at one reference lake was used for sedimenttoxicity comparisons (TAMS, 2002a). We believe that should be explored further in futurediscussions between the Nation and the response agencies, particularly since there are questions,

raised elsewhere, about whether all of the existing data for the site and all of the relevantliterature have been used in the Onondaga Lake risk assessment. There is a possibility that other appropriate reference data are available.


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3. The Evaluation of Bioaccumulationin Onondaga Lake Fish is NotSufficiently Protective

This chapter discusses the methods that were used in the RI (TAMS, 2002c) and BERA (TAMS,2002a) to evaluate human health and ecological risks associated with the bioaccumulation of mercury in fish, which currently is a primary risk driver for remedial decisions in the PRAP. Wewould like to discuss with the response agencies whether we have accurately interpreted their evaluation of mercury bioaccumulation and its use in risk calculations, before offering detailedcomments on potential improvements to the methodologies, or the incorporation of additional

information from the literature.

However, our primary initial comments regarding the evaluation of bioaccumulation in theBERA and FS include:

Only mercury bioaccumulation is addressed, but there are many additional contaminantsthat were identified as risk drivers for human health and wildlife, including PCBs,hexachlorobenzene, and PCDD/PCDFs. Bioaccumulation of these persistent, toxiccompounds could be as important as mercury for determining current and residual risk.We strongly recommend that these evaluations be undertaken and included in anydecision about remedial alternatives.

A BSQV was only developed for mercury. Because BSQVs are used to defineremediation goals, we strongly recommend that BSQVs be developed for all of the other

bioaccumulative substances of concern in Onondaga Lake.

The rest of this chapter presents our current understanding of the evaluation in the RI (TAMS,2002c) and BERA (TAMS, 2002a) of mercury bioaccumulation in fish. We raise severalquestions and issues throughout this summary and would like to discuss this critical issue further with the response agencies.

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Stratus Consulting Bioaccumulation Evaluation (Final, 6/28/2005)

3.1 The Onondaga Lake Fish Community Has Been Degraded andFish Are Unsafe to Eat because of Contamination

Historically, Onondaga lake supported a coldwater fishery for Atlantic salmon ( Salmo salar ),cisco ( Coregonus artedii ), American eel ( Anguilla rostrata ), and burbot ( Lota lota ) (NYSDEC,2004). Today, the lake supports a lower quality warmwater fish community dominated by

pollution-tolerant species such as gizzard shad ( Dorosoma cepedianum ), freshwater drum( Aplodinotus grunniens ), carp ( Cyprinus carpio ), and white perch ( Morone americana ).

Nevertheless, the lake still has a sportsfishery for channel catfish ( Ictalurus punctatus ),largemouth bass ( Micropterus salmonides ), smallmouth bass ( Micropterus dolomieui ), andwalleye ( Stizostedion vitreum ) (NYSDEC, 2004). However, a restrictive fish consumptionadvisory warns against any consumption of walleye, with all other species to be eaten no morethan once per month, because of contamination in the lake (NYSDOH, 1999, 2002, as cited in

U.S. EPA, 2005). The general advisory which is based on risks to consumers from mercury also carries the stipulation that infants, children under the age of 15, and women of childbearingage should eat no fish from the lake (NYSDOH, 2002, as cited in U.S. EPA, 2005). In addition tomercury, PCBs and dioxins are cited as restricting consumption of carp, channel catfish, andwhite perch to one meal per month for members of the general population.

3.2 Mercury Moves throughout Onondaga Lake

Mercury exposure pathways to biota include surface water, sediment, and dietary routes of exposure (U.S. EPA, 1997b). Dietary pathways of mercury exposure to fish include consumption

of benthic invertebrates exposed to mercury from sediments, pore water, and upwellinggroundwater, as well as consumption of fish contaminated through surface water and dietary pathways. The primary form of mercury that is bioaccumulated is organic methylmercury, themost toxic form of mercury (U.S. EPA, 1997b). Fish assimilate about 7-12% of methylmercuryin water passing across their gills (Wiener and Spry, 1996). Methylmercury accumulates rapidlyin the food chain and concentrations magnify in increasingly higher trophic levels (U.S. EPA,1997b).

Organic mercury (as methylmercury) can have a number of adverse effects on aquatic organisms.Documented impairments include inhibition of reproduction, reduction in growth, tissuehistopathology, reduced success in prey capture, alterations in blood chemistry and thyroidfunction, and a number of other adverse effects on metabolism and biochemical functioning(U.S. EPA, 1997b).

Adverse effects of mercury on humans can include neurotoxicity in the developing fetus,including impairment of motor skills and sensory function, and death at extremely high

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exposures (U.S. EPA, 1997b). In children and adults, impaired growth and development, behavioral abnormalities, and reduced reproductive success have also been documented(NYSDEC, 2004).

3.3 Evaluation of Surface Sediments, Only, Leads toUnder-Protectiveness

There are several problems with evaluating only the 1992 Onondaga Lake sampling data. First,the 1992 sampling only measured contaminant concentrations in the uppermost layer (0-2 cm) of lake sediments, although it was acknowledged that the bioactive layer typically extends at least15 cm (TAMS, 2002c). In addition, the RI found that mercury contamination is widespread inthe upper 2 m of sediments, and extends as deep as 2 m and 8 m in the Ninemile Creek delta andthe ILWD, respectively (TAMS, 2002c). Basing sediment target values on extrapolated uptakeinto fish tissue using 1992 surface sediment data is not protective of benthic biota, fish, or

piscivores. Furthermore, deeper sediments are of considerable concern, both because of dredging proposed under various remedial alternatives, and the realistic possibility of storms, waves, propeller wash, construction, etc., that could reduce the effectiveness of capping.

3.4 The Calculation of Biota-Sediment Accumulation FactorsIncludes Inappropriate Averaging and Extrapolations

Biota-sediment accumulation factors (BSAFs) are unitless factors that describe the relationship

between sediment and fish tissue concentrations of a contaminant, and are intended to serve as asimplified model of contaminant uptake (accumulation) from sediments to biota. BSAFs for fishare calculated as:

[contaminant concentration in fish]/[contaminant concentration in sediment]

To calculate BSAFs for Onondaga Lake fish, sampled fish were divided into two size classes(small fish, 3-18 cm in length; and large fish, 18-60 cm in length) and lake sedimentconcentrations for each group of each were averaged across either (1) the littoral zone only, or (2) the entire lake. Thus, two BSAFs were calculated for each fish size class: one for the littoralzone and one for the whole lake.

Results for mercury are presented in Table 3.1. All mercury in fish was assumed to be in theform of methylmercury, which was considered a conservative assumption becausemethylmercury is more harmful than inorganic mercury (Parsons, 2004).

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Table 3.1. Mercury BSAFs calculated for Onondaga Lake

Lake sediment averagesSmall fish(3-18 cm)

Large fish(18-60 cm)

Littoral 0.077 0.194Lakewide 0.093 0.235Mean 0.085 0.215Source: Parsons (2004).

We noted several problems with the approach used to calculate the Onondaga BSAFs, asdiscussed in the following sections.

3.4.1 Problems with averaging contaminant concentrations in fish based on size alone

Averaging contaminant concentrations over all fish on the basis of size alone obscures theinfluence of highly significant factors that affect contaminant accumulation in fish, such as thedegree of physical association with contaminated sediments, age, gender, species, feeding habits,trophic level, prey choice, time of year, water temperature, and pH. For example, smalllargemouth bass are likely to accumulate more methylmercury than large bluegill. This singlefactor also impacts the calculation of protective fish tissue concentrations. A better approachwould be to separate species into trophic levels before performing any size-based differentiation.For assessing risks to wildlife, the U.S. Environmental Protection Agency recommendsclassifying fish into trophic level 3 (forage fish) and trophic level 4 (higher level predators) in its

Mercury Study Report to Congress (U.S. EPA, 1997b). This approach would permit a more

comprehensive and protective evaluation of risk and alternative remedies.

3.4.2 Problems with extrapolation of fillet concentrations to whole body concentrations

The whole fish bodies consumed by fish-eating birds and mammals have higher concentrationsof contaminants (particularly bioaccumulating chemicals) than fish fillets. The BERAextrapolated fillet concentrations to whole body concentrations by multiplying by a factor of 0.7,

because that was the consensus of two literature values, instead of using the site-specificobserved ratio of 1.1 for mercury (TAMS, 2002a). This has the effect of reducing the predictedwhole-body mercury burden for fish by 30-40%.

In addition, averaging concentrations across all fish obscures how the ratio of fillet concentrationversus whole body concentration varies between different ages, species, genders, trophic levels,and prey choices of fish (Wiener and Spry, 1996). This obscures the highest uptake rates andreduces the protectiveness of the assessment.

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Furthermore, the distribution of concentrations should be investigated to see whether it isnormal. If it is lognormal, then the geometric mean of the concentrations is more representativeof the range of concentrations than the arithmetic mean.

3.5 The Mercury BSQV is Based on Low Effect Levels Ratherthan No Effect Levels

Similar to the mean PECQ that is used to predict the acute toxicity of sediments to benthic biota,a BSQV is intended to protect top-level consumers.

The BSQV formula is:

Target sediment concentration (BSQV) = [target fish tissue concentration/BSAF].

A BSQV value for mercury in sediments was back-calculated using the lowest observed adverseeffects values (LOAELs) for target fish tissue concentrations for mercury, together with thehighest lake-wide BSAF (Parsons, 2004). A BSQV value of 0.8 mg/kg was calculated byweighting the dietary consumption of each ecological receptor by its estimated percentconsumption of fish by size class. This size-class dietary weighting is not a protectiveassumption, because trophic level is a better predictor of a BSAF than size (U.S. EPA, 1997b).Additional protection could easily be afforded by examining the risks to predators of consuminga diet of 100% fish from trophic level 4.

In addition, the LOAEL is the value above which adverse effects are expected to occur, whereas

the no observed adverse effect level (NOAEL) is the level at which no adverse effects areexpected to occur. Therefore, use of the LOAEL is less protective than the NOAEL. It would bemore appropriate to use either the NOAEL, or a value intermediate between the NOAEL and theLOAEL, or a range made up of the two values, rather than the LOAEL alone. Mercury NOAELand LOAEL values for different ecological receptors for Onondaga Lake range from 0.009mg/kg wet weight (ww) to 0.6 mg/kg ww in fish tissue and 0.08 mg/kg dw to 2.00 mg/kg dw insediment (Table 3.2). By relying only on LOAELs, the PRAP is not adequately protectingconsumers of fish from mercury toxicity in the environment.

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Table 3.2. Target fish tissue and sediment concentrations formercury in Onondaga Lake expressed as NOAEL and LOAELvalues for different ecological receptors as derived in the FS

Fish issue mercury(mg/kg ww)

Sediment mercury(mg/kg dw)

Target receptor NOAEL LOAEL NOAEL LOAEL

Belted kingfisher 0.011 0.112 0.13 1.32Great blue heron 0.035 0.345 0.20 2.00Osprey 0.032 0.318 0.16 1.57Mink 0.009 0.093 0.11 1.09River otter 0.014 0.136 0.08 0.83Piscivorous wildlife 0.01 0.3Humans 0.2 0.6Source: Parsons (2004).

3.6 BSQVs Were Not Developed for Critical BioaccumulativeSubstances Other than Mercury

The FS did not calculate BSQVs for bioaccumulative contaminants other than mercury(e.g., PCBs, hexachlorobenzene, and PCDD/PCDFs) to drive remedial decisions. NYSDECassumed that all of the bioaccumulating substances would be sufficiently addressed by

addressing mercury (TAMS, 2002a). However, very high levels of many compounds, including bioaccumulating substances, will be left behind under the preferred remedy (see Chapter 5 of thisdocument). There are sufficient data to calculate the residual risk for the other bioaccumulatingcompounds under various remedial scenarios, including an evaluation of potential cappingfailure. Furthermore, many of the other bioaccumulating substances are even more toxic and

bioaccumulate more strongly than mercury. Therefore, the residual risk under the preferredalternatives, and under realistic cap failure scenarios is higher than an evaluation of mercuryalone would indicate.


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4. A More Thorough and Protective Risk Assessment Justifies More Dredging thanthe Preferred Alternative

The main purpose of remedial investigations, risk assessments, and feasibility studies is toevaluate realistic alternatives for cleaning up contaminated sites. The PRAP then presents theresponse agencies position and justification to the public regarding the preferred alternative, andthe ROD will finalize the response agencies remedial decisions after considering publiccomments. Although all nine Superfund criteria must be weighed, the primary motivation for more complete, more reliable, and faster cleanup is reduction of current and future risk to human

health and the environment, while the primary motivation for less complete, less reliable, andslower cleanup is cost and cost-effectiveness. In this chapter, we present the reasons why a morethorough and protective risk assessment, as described in Chapters 2 and 3, would provideadditional motivation and justification for a more complete and more reliable cleanup throughadditional dredging, as represented by Alternatives 5 through 7.

4.1 The Remediation Objectives Are Elimination or Reduction of Potential Health and Environmental Impacts

According to the PRAP, the primary objective of remediation in Onondaga Lake is to remediatesources of contamination, particularly in sediments, such that any potential future health andenvironmental impacts are eliminated or reduced, to the extent practicable (NYSDEC, 2004,

p. 24). This chapter discusses the criteria that were used to select remedial alternatives, the mainfeatures of the alternatives that were evaluated, the relative effectiveness of the differentalternatives, and the preferred remedy approved by NYSDEC.

4.2 PECQs Are Used to Evaluate Remedial Alternatives

For all but one of the lake-wide remediation alternatives, the primary criteria used for theremediation of sediment toxicity are a mean PECQ of 1 and a mercury PEC of 2.2 mg/kg

(NYSDEC, 2004). A mean PECQ of 1 was interpreted to indicate that, on average, theconcentrations of all the CPOIs in the sediments do not exceed their corresponding PECs(NYSDEC, 2004). However, as discussed in Chapter 2, the derivation of the SECs and PECs wasnot sufficiently protective, and risk averaging of the resultant PECQs further reduced the

protectiveness and transparency of the critical criteria used to evaluate alternatives. For a more

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Stratus Consulting Justification for Additional Dredging (Final, 6/28/2005)

protective analysis, all hazard quotients (PECQs) should be based on the complete site-specificdata and relevant literature, and then, instead of averaged, summed, summed by chemical class,or at a minimum, evaluated separately, with the highest hazard quotient driving risk managementdecisions. Even in places where mercury has the highest hazard quotient, this analysis would bemuch more transparent and meaningful than risk averaging.

4.3 Summary of the Main Features of the DifferentRemediation Alternatives

As discussed in the PRAP (NYSDEC, 2004), each of the remedial alternatives involves somecombination of:

DredgingDisposal and treatment at a sediment consolidation area (SCA)Isolation cappingThin-layer cappingAeration of the hypolimnionMonitored natural recovery (MNR)Habitat enhancement.

With the exception of Alternative 1, the no action alternative, the different alternatives involvesuccessively greater depths of excavation and therefore increasing volumes of waste removal(NYSDEC, 2004). Alternatives 2 through 6 involve removal of depths up to 1, 2, 3, 5, and 8 mwithin the ILWD in SMU 1, the most significant area of contamination.

The PRAP notes that the long-term effectiveness of the alternatives increases with increasingamounts of waste removed, and that the reliability of the cap increases with removal of the moreconcentrated wastes. Alternative 4 includes hot spot removals to a depth of 3 m and providesgreater reliability than Alternatives 2 and 3. Alternative 5 increases the area of removal to adepth of 5 m, but does not target hot spots, and therefore is not considered more reliable thanAlternative 4.

Alternatives 4 through 6 would also remove non-aqueous phase liquids (NAPLs), which are aconcern in SMU 2, to a depth of 9 m (NYSDEC, 2004). This would further reduce contaminationand increase cap reliability. Alternatives 6 and 7 would remove the most material, but this would

exceed the capacity of the SCA, resulting in higher costs. Alternative 7 is the most costlyalternative, but it is also the only alternative that attempts to address chronic toxicity by use of alower cleanup criterion, the acute ER-L, which is the sediment concentration below whichacutely toxic effects are expected to rarely occur.

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4.4 Summary of the Preferred Remedy

The preferred remedy would include a combination of dredging and capping of the maincontaminants of concern in Onondaga Lake, including mercury, BTEX, napthalene, chlorinated

benzenes, and PCBs. Dredging would remove about 2,653,000 cubic yards (cy) of the nearshoresediments containing toxic contaminants, with the majority of dredging in the southern portion of the lake near the former Honeywell facilities.

In addition to dredging, there would be isolation capping of about 1.72 km 2 of the littoral zone of the lake out to water depths of 9 m. The area of proposed isolation capping includes about 42%of the surface area of the littoral zone of the lake. There would also be thin-layer capping of about 0.6 km 2 of contaminated sediments in the profundal (deep) zone of the lake. This amountsto about 8% of the surface area of the profundal zone.

In addition to these remedial activities, an aeration (oxygenation) pilot study would be conductedto address methylation of mercury in the water column of the deep zone of the lake (NYSDEC,2004). If found to be effective, aeration would be fully implemented, followed by monitoring of natural recovery.

Contaminated sediments and wastes removed from the lake would be disposed of in an SCA inan existing waste location (NYSDEC, 2004). The sediment and waste consolidation would

produce effluent water, which would be treated to remove solids and contaminants at a water treatment facility to be constructed as part of the remediation. The treated water would then bereturned to the lake.

4.5 The Preferred Remedy is Not Sufficient

The comparative analysis by NYSDEC (2004) of the relative effectiveness of the different lake-wide remediation alternatives is presented in Table 4.1. However, improvements in the risk assessment (see Chapters 2 and 3) would result in more protective PECQs, which would lead tohigher calculations of current risk, and residual risk for areas not dredged under the variousalternatives. Therefore, more dredging would be justified, as presented in Alternatives 5through 7.

Furthermore, capping is a risky alternative, particularly in light of the fact that dredging

equipment will be mobilized and functioning in the lake under all but the no-action alternative.The proposed capping will greatly increase the cost of additional dredging in the future if theremedy proves insufficient. A much better strategy is to dredge all of the sediments contaminatedabove reasonable thresholds, followed by adequate monitoring of the sediments, water column,

benthic organisms, fish, and fish eating birds and mammals (including humans) of Onondaga

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Stratus Consulting Justification for Additional Dre

Table 4.1. Comparison by the NYSDEC of the remedial alternatives presented in the PRAPAlternative 1 a Alternative 3 cAlternative 2 b Alternative 4 d Alternative 5

Overall protection of human healthand the environment

Not protective Moderate Moderate Moderatelyhigh

Moderatelyhigh

Compliance with applicable or relevant and appropriate requirements

Not compliant All generally compliant except possibly for the m NY state surface water standard for total mercury (0.

Long-term effectiveness and permanence

Not effective Moderate Moderate Moderatelyhigh

Moderatelyhigh

Reduction of toxicity, mobility, or volume through treatment

None Moderate Moderate Moderatelyhigh

Moderatelyhigh

Short-term effectiveness Not effective Moderatelyhigh

Moderatelyhigh

Moderatelyhigh

Moderatelyhigh

Implementability High High High High Moderately

highPresent-worth cost (millions) $0 $312 $370 $451 $537

Note: Alternatives 2 through 6 are based on the mean PEC quotient of 1 plus the mercury PEC of 2.2 mg/kg. Alternative 7 is b

a. No action. b. Dredge for no loss of surface area/human & ecological (NLSA/H&E) + isolation capping in SMUs 1-7; NAPL removal to 4areas with higher groundwater upwelling in SMUs 3 and 6/thin-layer capping, aeration, MNR in SMU 8.c. Alternative 2 plus up to 25% removal of the ILWD in SMU 1.d. Alternative 3 plus removal in hot spot areas to a depth of 3 m in the ILWD and NAPL removal to 9 m in SMU 2.e. Alternative 4 with up to 5 m of removal in the ILWD in SMU 1.f. Full removal (up to 8 m) in SMUs 1, 2, 3, 4, 6, and 7; isolation capping in SMU 5; thin-layer capping, aeration, MNR in SMg. Same as Alternative 6 but cleanup to ER-L criteria rather than mean PECQ of 1 plus mercury PEC.

Source: NYSDEC (2004).

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Lake to determine whether the remedy was sufficient. Then, additional dredging can be performed, as needed.

It would be ironic if the dredging equipment were switched off, just as the dredge head reachessediments so contaminated that they would likely trigger remedial action if discovered at another site. Table 4.2 presents the residual concentrations that would be left behind under the preferredalternative, and calculates how many times above the safe level, as represented by the PECs,that this is. The PEC are themselves too high, because of the inappropriate use of geometricmeans and because chronic toxicity was not addressed (see Chapter 2); and the PECQs, residualto dredging, are as much as 62,000 times higher than the PECs (i.e., hazard quotients are muchhigher than 1, even using the PECs). Furthermore, 51% of sediment samples from OnondagaLake showed actual toxicity (40 of 79 sediment samples collected in 1992; TAMS, 2002a), butonly 13% of contaminated sediments from Onondaga would be removed under the preferredalternative (2,653,000 cy removed of 20,091,000 cy contaminated; NYSDEC, 2004).

Table 4.2. Residual concentrations and hazard quotients left behind by thepreferred alternative

CPOI

Residual concentration withpreferred alternative

(mg/kg) aPECs

(mg/kg) b

Residual hazard quotientwith preferred

alternative c

Benzene 208 0.150 1,387

Chlorobenzene 114 0.428 266

Dichlorobenzenes 90 0.239 377

Naphthalene 20,573 0.917 22,435

Xylenes 142 0.561 253Ethylbenzene 1,655 0.176 9,403

Toluene 2,626 0.042 62,524

Mercury 2,924 2.2 1,329

a. From the PRAP, describing concentrations that trigger additional dredging in the ILWD. b. From the BERA, Table ES-3.c. Calculated as the maximum residual concentration allowed in ILWD, post-dredging, divided bythe PEC. Residual hazard quotients above 1 are potentially problematic, particularly if the cap fails.

Sources: TAMS (2002a) and NYSDEC (2004).

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5. Residual Risk Calculations Must beImproved Before Remedial AlternativesAre Compared

Chapter 4 shows that removal of contaminants, additional to those targeted by the preferredalternative, is justified. This chapter presents additional comments about how residual risk calculations must be improved to ensure an accurate comparison of remedial alternatives. For example, although the FS acknowledges that water, sediments, and the food chain all transportcontaminants, only the sediment pathway was evaluated in determining potential residual risk tofish (Parsons, 2004, Appendix I). In addition to sediment-based exposure pathways, fish

accumulate many Onondaga Lake contaminants directly via opercular-uptake as well as via preythat are themselves exposed via opercular uptake. However, the surface water pathway wasexcluded from the residual risk calculations, both as an independent pathway and as a source of cumulative exposure to contaminants. Furthermore, one form of cap failure is movement of groundwater carrying high levels of contamination, including both NAPLs and dissolved phasechemicals. This groundwater could, in turn, serve as a pathway to surface water, further emphasizing the importance of the water column pathway in calculating residual risk,

particularly under cap failure scenarios.

In addition, there are uncertainties underlying the estimates of risk reduction presented in the FS(Parsons, 2004, Appendix I). Although these uncertainties were acknowledged, there was no

quantitative uncertainty analysis or evaluation of the sensitivity of results to assumptions aboutthe values of key parameters. This is quite important because one of the key differences betweenin-place remedies like capping and removal remedies like dredging is increased uncertaintyabout the ultimate fate of in-place contamination, and those uncertainties increase over longer

periods into the future. Therefore, even if the cap was as effective as dredging, initially, fullaccounting of differential uncertainty in residual risk between capping and dredging should be

presented.

All of the lake-wide remediation alternatives assume that concentrations of contaminants inwater and sediment will be reduced as a result of (1) reductions in loadings from upland and in-lake sources, (2) aeration of the hypolimnion, and (3) sediment remediation (Parsons, 2004,Appendix I). Some of the issues related to residual risks following these actions are discussed inthe following sections, with a focus on mercury. Ideally, a much more extensive analysis of

potential residual risks would be conducted, particularly since remedial decisions for other operable units and connected sites could range from inaction and delay, to natural recovery, toin-place immobilization attempts, to aggressive removals. A full accounting of residual risk

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Stratus Consulting Improving Residual Risk Calculations (Final, 6/28/2005)

should account for the variability in potential loadings from these other sources, rather than auniform assumption of complete, quick, and effective cleanup.

5.1 Reductions in Contaminant Loadings

Sources of mercury to Lake Onondaga include groundwater, tributaries, and the Metro Plant(Parsons, 2004, Appendix I). The FS assumed that upland control will reduce or eliminate totalmercury and methylmercury from Honeywell-impacted tributaries and groundwater, and thatimprovements to the Metro Plant have resulted in a 50% reduction to loadings from this source.We were unable to find the underlying justification for assuming that upland controls willreduce or eliminate mercury from tributaries and groundwater, and there are no data on theeffectiveness of plant upgrades. Thus, we were unable to determine if these assumptions arereasonable.

We also note that the timing of the cleanup of Onondaga Lake, and the effectiveness of remedialdecisions there, is directly dependent on the decisions and timing for the operable units adjacentto and upstream of the lake. The National Oil and Hazardous Substances Pollution ContingencyPlan (NCP) defines an operable unit as a discrete action that comprises an incremental steptoward comprehensively addressing site problems (NYSDEC, 2004). If actions in the operableunits do not precede actions that are dependent on them, subsequent actions may not achieve thecleanup success that is assumed.

In-lake sources of mercury include littoral sediment (mostly in the ILWD, in the southwest portion of the lake) and methane gas ebullition (releases) from the profundal sediments (TAMS,

2002c). The FS assumed that capping or dredging will eliminate mercury releases from theILWD and that thin-layer capping, aeration (oxygenation), and natural recovery will significantlyreduce mercury releases from profundal sediments (Parsons, 2004, Appendix I). Source controlis assumed to result in an 81 to 95% reduction in total mercury loadings to the lake, and acombination of source control and aeration is assumed to result in an 82% reduction inmethylmercury loading (Parsons, 2004, Appendix I). However, we have not yet reviewed themodeling studies that are the basis for these estimates. Support for these reductions should be

provided, together with a reasonable uncertainty/sensitivity analysis.

5.2 Aeration of Hypolimnion

According to information provided in the PRAP, the primary source of methylmercury to thewater column is assumed to be the methylation of mercury in the hypolimnion during thesummer, when conditions in the hypolimnion are anoxic (NYSDEC, 2004). When the lakestratifies in the summer, bacteria and other organisms are isolated from the epilimnion and

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confined to the hypolimnion. During this time, these organisms deplete the oxygen in thehypolimnion and create anaerobic conditions conducive to the production of methylmercury.Small quantities of methylmercury in the hypolimnion diffuse to the epilimnion in the summer.But during the fall turnover, large quantities of methylmercury are released from thehypolimnion, substantially increasing the methylmercury in the upper layer of lake waters. Thisresults in a large export of mercury to downstream areas of the lake (NYSDEC, 2004).

Aeration (oxygenation) of the hypolimnion is intended to reduce the methylation of mercury inthe hypolimnion during summer (NYSDEC, 2004). Aeration would involve introducing oxygento the hypolimnion to reduce the hypoxic conditions that promote methylation. The PRAP notesthat aeration has been performed in other lakes, but acknowledges that aeration has rarely beenused to control methylmercury production (NYSDEC, 2004). Therefore, the effectiveness of aeration, and the residual risks following aeration, are unknown.

According to the PRAP, a pilot study would be conducted in the water column of the deep zoneof the lake to determine the effectiveness of aeration, and, if found to be effective, aerationwould be fully implemented (NYSDEC, 2004). However, before the pilot study is conducted it ismisleading to discuss aeration as though it is known to be effective, as we noted in many sectionsof the documents we reviewed. Therefore, the evaluation of residual risk must, at a minimum,consider the range of possible effectiveness of aeration to include partial success and failure,

both realistic possibilities.

In addition, there is the possibility that oxygenation of the water column would have a number of negative effects. As pointed out in Chapter 11 of the BERA (TAMS, 2002a), oxygenation of thehypolimnion could simply shift the anoxic boundary from the water column to the sediment,

leaving more contaminants available at the sediment surface. In turn, this would increase the bioavailability of contaminants to the aquatic food web (TAMS, 2002a).

5.3 Sediment Remediation

5.3.1 Effectiveness of isolation capping

Isolation capping involves the placement of an engineered cap on top of contaminated sediment,which can help to prevent or slow the movement of contaminated porewater into the water column, minimizing exposure of benthic organisms to contaminated sediment (NYSDEC, 2004).Because there are varying degrees of contamination in the sediments in different parts of thelittoral zone in Onondaga Lake, a model was developed to evaluate cap effectiveness in eachlittoral zone SMU. The effectiveness of capping depends on factors such as contaminantconcentrations below the cap and the rate at which groundwater flows up through the cappedsediments (NYSDEC, 2004). Therefore, accurate model predictions require good information on

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the rates of these processes, as well as a sensitivity analysis to compare predictions under different rate assumptions. We have not identified such an analysis in the Onondaga Lakedocuments that we have reviewed to date.

Another important assumption concerns the depth of the biologically active zone (bioturbationlayer). Contaminants may be transported to the surface of the cap by organisms mixing thesediment. The capping model apparently assumes that the bioturbation layer is less than 15 cmabove the chemical isolation area (Parsons, 2004, Appendix I). However, the justification for thisassumption is not provided. While many freshwater organisms show bioturbation activity withinthe top 15 cm of sediments, crustaceans can be found turning over sediments as deep as 3 m(Pennak, 1978). Furthermore, waves, storms, propeller wash, and construction are all certainties,

but we have not seen any analysis of the effects of these fac

technical analysis of baseline ecological risk assessment and prap for mercury in onondaga lake

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