woodward-clyde consultants · woodward-clyde consultants table of contents section page no....

Woodward-ClydeConsultantsEngineering & sciences applied to the earth & its environment f-~? f ' ' '•

April 29, 199288C2076-4V ,..

'' •t'r .•!; "3 " , U.. •«•••--Mr. Randy SturgeonEnforcement Project ManagerU.S. Environmental Protection AgencyRegion 3, 841 Chestnut StreetPhiladelphia, PA 19107

Re: Risk Assessment, Du Font-Newport SiteTransmittal of Environmental Evaluation

Dear Mr. Sturgeon:

On behalf of E.I. du Pont de Nemours and Company, Inc. (Du Pont), Woodward-ClydeConsultants (WCC) is pleased to submit by Federal Express to the USEPA, six copies ofthe revised Environmental Evaluation for the Risk Assessment at the Du Pont-NewportSite. This Environmental Evaluation is Volume 2 of the two-volume Risk Assessmentfor the Site. This Environmental Evaluation was prepared in accordance with RiskAssessment Guidance for Superfund, Volume II, Environmental Evaluation Manual. Itresponds to all USEPA comments received on the original document which wassubmitted July 30, 1991.

If you have any questions, please do not hesitate to call Mr. Roger Gresh at WCC, orMr. Joel Karmazyn at Du Pont.

Very truly yours,

Jon I. Parker, Ph.D.Senior Staff Scientist

Ceil ManciniProject Scientist

Roger T. Gresh, P.G.Project Manager .JIP/CM/RTG/kcs/DPN5end.cc: A. Hiller, DNREC J. Karmazyn, Du Pont

S. Sury, CIBA-GEIGY N. Griffiths, Du PontF. Hannigan, CIBA-GEIGY C. Trmal, Du PontG. Wise, CIBA-GEIGY G. Foley, Du PontB. Butler, Du Pont M. Nicholson, Du Pont

5120 Butler Pike • Plymouth Meeting, Pennsylvania 19462215-825-3000 • Fax 21 5-834-0234 : m p <-y t n I | I

ENVIRONMENTAL EVALUATIONDUPONT-NEWPORT SITENEWPORT, DELAWARE

For:

U.S. Environmental Protection AgencyRegion 3841 Chestnut StreetPhiladelphia, Pennsylvania 19107

Prepared for:

E.I. du Pont De Nemours and Company, Inc.Du Pont ChemicalsRoom 122281007 Market StreetWilmington, DelawareApril 29, 1992

Prepared by.

Woodward-Clyde Consultants5120 Butler PikePlymouth Meeting, Pennsylvania 19462

Project No. 88C2076-4V

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Woodward-ClydeConsultants

TABLE OF CONTENTS

Section Page No.

EXECUTIVE SUMMARY ES-1

1.0 INTRODUCTION 1-1

1.1 BACKGROUND 1-11.2 OBJECTIVE 1-31.3 SCOPE 1-3

2.0 ENVIRONMENTAL SETTING 2-1

2.1 REGIONAL SETTING 2-12.2 STUDY AREA DESCRIPTION 2-2

2.2.1 North Disposal Site 2-32.2.2 South Disposal Site 2-32.2.3 Christina River 2-42.2.4 Wetlands 2-72.2.5 Terrestrial Habitats 2-112.2.6 Sensitive Habitats 2-12

3.0 WETLANDS INVESTIGATION SAMPLING AND ANALYSIS 3-1

3.1 CHRONOLOGY 3-13.2 DATA COMPARISONS 3-1

3.2.1 Ecological Endpoints 3-13.2.2 ARARs and Guidelines . 3-2

3.3 PHASE I RIVER STUDY 3-5

3.3.1 Objectives 3-53.3.2 Scope 3-53.3.3 Results 3-5

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TABLE OF CONTENTS (continued)

Section Page No.

3.4 PHASE H WETLANDS INVESTIGATION 3-6


3.5 PHASE HI WETLANDS INVESTIGATION 3-8


3.6 SUPPLEMENTAL PHASE HI WETLANDS 3-11INVESTIGATION

11

o3.6.1 Objectives3.6.2 Scope3.6.3 Results 3-13

4.0 CHEMICAL CONSTITUENTS CHARACTERIZATION 4-1

4.1 DISPOSAL HISTORY 4-14.2 SURFICIAL SOILS > 4-14.3 SEDIMENT 4-3

4.3.1 Normalization Approach 4-443.2 Results . 4-6

432.1 North Disposal Site Drainageways 4-743.2.2 South Disposal Site Pond and

Drainageways 4-114.3.2.3 Christina River 4-13

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Section Page

4.4 SURFACE WATER 4-18

4.4.1 North Disposal Site Drainageways 4-194.4.2 South Disposal Site Pond and

Drainageways 4-214.4.3 Christina River 4-22

4.5 GROUNDWATER SEEPS 4-254.6 BIOLOGICAL TISSUES 4-304.7 SUMMARY 4-32

*

5.0 CONSTITUENTS OF CONCERN 5-1

5.1 CONSTITUENTS OF INTEREST 5-15.2 POTENTIAL CONSTITUENTS OF CONCERN 5-25.3 CONSTITUENTS OF CONCERN 5-35.4 TOXICITY PROFILES 5-7

5.4.1 Barium 5-85.4.2 Cadmium . 5-105.4.3 Chromium 5-135.4.4 Copper 5-155.4.5 Lead • 5-185.4.6 Mercury 5-215.4.7 Zinc 5-23

6.0 ECOLOGICAL EXPOSURE . 6-1

6.1 ENVIRONMENTAL TRANSPORT PATHWAYS 6-16.2 EXPOSURE EVALUATION - AQUATIC RECEPTORS 6-2

6.2.1 North Disposal Site Draihageway 6-46.2.2 South Disposal Site Pond 6-56.2.3 South Disposal Site Wetlands 6-66.2.4 Christina River 6-8

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Section Page

6.3 EXPOSURE EVALUATION - TERRESTRIAL/WETLAND RECEPTORS 6-9

6.3.1 Exposure Scenarios 6-11

6.3.1.1 North Disposal Site 6-126.3.1.2 North Disposal Site Drainageways 6-126.3.1.3 South Disposal Site 6-136.3.1.4 South Disposal Site Pond 6-146.3.1.5 South Disposal Site Wetlands 6-146.3.1.6 Christina River - 6-146.3.1.7 Reference Sites 6-15

6.3.2 Toxicity Screen Methodology 6-156.33 Toxicity Screen Results

7.0 IMPACT CHARACTERIZATION

7.1 NORTH DISPOSAL SITE 7-17.2 NORTH DISPOSAL SITE DRAINAGEWAYS 7-27.3 SOUTH DISPOSAL SITE 7-47.4 SOUTH DISPOSAL SITE POND 7-57.5 SOUTH DISPOSAL SITE WETLANDS 7-67.6 CHRISTINA RIVER 7-87.7 SUMMARY OF IMPACTS 7-107.8 CONCLUSIONS . 7-13

8.0 UNCERTAINTIES AND LIMITATIONS OF ANALYSIS 8-1

8.1 FACTORS WHICH MAY OVERSTATE RISK 8-18.2 FACTORS WHICH MAY UNDERSTATE RISK 8-4

9.0 REFERENCES . 9-1

IV

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LIST OF TABLES

TABLE 1 FISHES COLLECTED IN THE TIDAL PORTIONOF THE CHRISTINA RIVER 1988 - 1990

TABLE 2 BENTHIC MACROINVERTEBRATES COLLECTEDFROM THE TIDAL CHRISTINA RIVER, WHITE CLAYCREEK, NORTH AND SOUTH DISPOSALSITE WETLANDS, 1988 THROUGH 1990

TABLE 3 PLANT SPECIES OBSERVED IN WETLANDSASSOCIATED WITH THE DUPONT-NEWPORTSITE AND TIDAL FRESHWATER WETLANDSOF DELAWARE

TABLE 4 COMPOSITE LIST OF REPTILES AND AMPHIBIANSOBSERVED IN TIDAL FRESHWATER WETLANDSTHROUGHOUT DELAWARE

TABLE 5 COMMON NAMES OF BIRD SPECIES SIGHTEDIN CHURCHMAN'S MARSH 1965-1966 AND 1980

TABLE 6 COMPOSITE LIST OF MAMMALS OBSERVED INTIDAL FRESHWATER WETLANDS THROUGHOUTDELAWARE

TABLE 7 SEDIMENT QUALITY GUIDELINES

TABLE 8 WATER QUALITY CRITERIA FOR THEPROTECTION OF FRESHWATER AQUATIC LIFE (PPM)

TABLE 9 PHASE II SAMPLING AND ANALYSIS PLANSEPTEMBER 1988

TABLE 10 AQUATIC SAMPLING PLAN - PHASE IIIWETLANDS INVESTIGATION - AUGUST 1989


TABLE OF CONTENTS (continued)ued)

LIST OF TABLES (continued)

TABLE 11 SUPPLEMENTAL PHASE HI WETLANDSINVESTIGATION - OCTOBER 1990

TABLE 12 SUMMARY OF SURFICIAL SOIL CHEMISTRYAT THE DUPONT-NEWPORT T TSPOSAL SITES

TABLE 13 MAXIMUM AND NORMALIZE *ONCENTRATIONS OFCONSTITUENTS OF INTERES1 ND THE ENRICHMENTFACTORS FOR THE SURFICIAL SEDIMENT SAMPLES

TABLE 14 SUMMARY OF METAL CONCENTRATIONS (PPM) INNON-FILTERED SURFACE WATER FROM THE NORTHDISPOSAL SITE DRAINAGEWAYS

TABLE 15 SUMMARY OF METAL CONCENTRATIONS (PPM) INNON-FILTERED SURFACE WATER FROM THE SOUTHDISPOSAL SITE DRAINAGEWAYS

TABLE 16 SUMMARY OF METAL CONCENTRATIONS (PPM)IN NON-FILTERED SURFACE WATER FROM THECHRISTINA RIVER TIDAL STUDY

TABLE 17 SUMMARY OF METAL CONCENTRATIONS (PPM) INNON-FILTERED GROUNDWATER SEEPAGE SAMPLES

TABLE 18 EFFECTS OF CADMIUM, CHROMIUM, COPPER,LEAD, MERCURY AND ZINC ON FISHES

TABLE 19 ENVIRONMENTAL EXPOSURE SCENARIOS

TABLE 20 GEOMETRIC MEANS OF SEDIMENT SAMPLES

TABLE 21 WEIGHTED GEOMETRIC MEAN CALCULATIONSFOR NUPHAR TISSUE SAMPLES

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LIST OF TABLES (continued)

TABLE 22 WEIGHTED GEOMETRIC MEAN CALCULATIONSFOR RS15 NUPHAR TISSUE SAMPLES

TABLE 23 INGESTION PARAMETERS FOR TERRESTRIALRECEPTORS

TABLE 24 FOOD INTAKE (FI) EQUATIONS FORTERRESTRIAL SCENARIOS

TABLE 25 TOXICITY INFORMATION FOR TERRESTRIALRECEPTORS

TABLE 26 SELECTED TOXICITY SCREENING INTAKEVALUES FOR TERRESTRIAL RECEPTORS

TABLE 27 TOXICITY SCREEN FOR SEDIMENT INGESTIONTERRESTRIAL RECEPTORS

TABLE 28 TOXICITY SCREEN FOR SOIL INGESTIONTERRESTRIAL RECEPTORS

TABLE 29 TOXICITY SCREEN FOR FOOD INGESTIONTERRESTRIAL RECEPTORS

TABLE 30 TOXICITY SCREEN FOR FOOD AND SEDIMENTINGESTION

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LIST OF FIGURES

FIGURE 1 SITE AREA - 1948

FIGURE 2 SITE AREA - 1987

FIGURE 3 WETLAND SAMPLING STATIONS

FIGURE 4 CHRISTINA RIVER SAMPLING STATIONS

FIGURE 5 SURFACE SOIL SAMPLE LOCATIONS

FIGURE 6 CORRELATION/REGRESSION PLOTS OF ALUMINUMVERSUS SEDIMENT MUD AND ORGANIC CONTENT

FIGURE 7 WETLAND SEDIMENT SAMPLING STATIONS, METALSEXCEEDING GUIDELINES, MAXIMUM CONCENTRATORAND ENRICHMENT FACTORS

FIGURE 8 CHRISTINA RIVER SEDIMENT SAMPLING STATIONS,METALS EXCEEDING GUIDELINES, MAXIMUMCONCENTRATIONS AND ENRICHMENT FACTORS

FIGURE 9 DISTRIBUTION OF SEDIMENT ENRICHMENTFACTORS FOR METALS IN THE CHRISTINA RIVER

FIGURE 10 WETLAND SURFACE WATER AND GROUNDWATERSEEP SAMPLING STATIONS, METALS EXCEEDINGCRITERIA AND MAXIMUM.CONCENTRATIONS

FIGURE 11 COMPOSITE WATER SAMPLES FROM GROUNDWATERSEEPAGE LOCATIONS

FIGURE 12 CONCEPTUAL TRANSPORT MODEL

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LIST OF APPENDIXES

APPENDIX A PHASE II WETLANDS INVESTIGATIONDATA TABLES

APPENDIX B PHASE III WETLANDS INVESTIGATIONDATA TABLES

APPENDIX C SUPPLEMENTAL PHASE III WETLANDSINVESTIGATION DATA TABLES

APPENDIX D SEDIMENT QUALITY TRIAD

IX


EXECUTIVE SUMMARY

INTRODUCTION

Woodward-Clyde Consultants (WCC) conducted an Environmental Evaluation (EE) of theDu Font-Newport Site located on the Christina River in Newport, Delaware as part of theRemedial Investigation/Feasibility Study required under the Comprehensive EnvironmentalResponse, Compensation and Liability Act. The EE represents Volume II of the two-volume Risk Assessment prepared for the Newport Site. Volume I is the Human HealthEvaluation, which is presented as a separate, companion document. The evaluationfollowed the Risk Assessment Guidance for Superfund, Volume n, EnvironmentalEvaluation Manual (1989) and responded to comments from the U.S. EnvironmentalProtection Agency (EPA) project team.

SCOPE

The purpose of the EE was to identify specific locations in the Newport Site study areawhere the extent of apparent or potential environmental impact might warrant considerationfor the Feasibility Study. The EE utilized data generated during the three-phase RemedialInvestigation, which included four periods of field activity for the Wetlands Investigation(Phase I, Phase II, Phase III, and Supplemental Phase III).

Specific components of the work plans prepared for conducting the Wetlands Investigations,including test media, analyses to be performed, station locations and data manipulation,were defined in response to directives from the EPA. Data generated during the WetlandsInvestigations included: surface water and sediment chemistry; sediment physicalparameters; benthic community analyses; solid phase toricity testing using Chironomustentans and Hyalella azteca: elutriate phase toxicity testing using Pimephales promelas andCeriodaphnia dubia: fish tissue analyses; and vegetation tissue analyses. In addition, soilschemical data collected as part of other field efforts associated with the RemedialInvestigation were used to evaluate risk to terrestrial receptors associated with the Site. The

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ecological constituents of concern for the Du Font-Newport Site are: barium, cadmium,copper, chromium, lead, mercury, and zinc. These constituents of concern were derivedfrom historical Site data, prevalence of the constituents in wetlands and river media,comparison of concentrations with guideline values, and toxicological properties arbiogeochemical fate.

Following characterization of the Site media and identification of the constituents ofconcern, an exposure evaluation was conducted to define the potential for risk or impact toaquatic and terrestrial receptors in the study area. Aquatic impact was characterized basedon media chemistry, benthic community analyses and toxicity testing collected during thewetlands investigations. Risks to terrestrial receptors were evaluated by comparingenvironmental concentrations to toxicity screening values from relevant scientific literaturefor the deer mouse, muskrat and great blue heron.

ECOLOGICAL EXPOSURE

For ecological exposure to occur, constituents of concern must be transportedenvironmental pathways to reach ecological receptors. If the chemical concentration is highenough, an impact can potentially occur. In this exposure assessment, the two potentialroutes of exposure to the constituents of concern are direct contact and ingesiion. The threetransport pathways at the Du Font-Newport Site are groundwater, stormwater runoff, andsurface water.

The two exposure routes initially considered in the exposure evaluation were: (1) directcontact with soils, surface water or sediments; and -(2) ingestion of soils, surface water,sediments or biota (flora or fauna). Owing to the predominant environmental fate of theecological constituents of concern (i.e., adsorption to soils and sediments), and the fact thatingestion provides a worst case exposure route, ingestion of soils and sediments wasevaluated in the terrestrial and wetland ecological exposure scenarios. Based on theseassumptions a complete list of potential exposure scenarios was defined for each portion ofthe study area. The list of potential exposure scenarios was further scrutinized to defineprobable exposure scenarios for the North Disposal site, North Disposal site drainageway,

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South Disposal site, South Disposal site pond, South Disposal site wetlands, and ChristinaRiver in the vicinity of the Du Font-Newport Site. Compositely, these scenarios representthe ecological exposure assessment for the entire Site. Exposed receptors and scenarioswere requested by the EPA in a meeting held March 5, 1992 and subsequentcorrespondence from EPA to Du Pont of March 19 and 20, 1992.

SUMMARY OF IMPACTS

Aquatic Risk

The aquatic risk evaluation portion of this EE has identified general locations in the studyarea which can be placed into one of three categories as follows:

• Areas that are apparently impacted based on measurable ecological endpointsdue to Site-related constituents or activities

• Areas which may be impacted but where data is either limited or notavailable

• Areas that are not impacted due to Site-related activities or constituents basedon the weight of evidence of biological data collected

The central portion of the North Disposal site drainageway from the vicinity of Station A§07to the vicinity of Station ASG9 has been impacted by Site-related constituent Surficialsediment levels of all constituents are much greater than EPA Threshold Value Guidelines.Stations AS07 and AS08 had some of the highest geochemical enrichment factors among allstations sampled. Impoverished benthic communities, and significantly poor survival intoxicity testing as compared to field reference stations, also suggest that an impact exists inthe central portion of the drainageway. Based on the data, constituent concentrations andimpacts decrease moving downstream from Station AS07.

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Ecological" endpoints (i.e., benthic density and richness, and toxirity test results) usedcharacterize the South Disposal site wetlands provide contradictory information. Benthiccommunity data suggest impacts; toxitity test survival using the minnow, water flea andmidge larvae in Station AS03 surface water or sediment was not significantly different thantljje level of survival at the field reference location or in the negative lab controlInsufficient data are available to identify the extent of the area of benthic impact, but sincesediment chemistry improves markedly with distance from the benn, it is assumed thatecological impact to benthic macroinvertebrates is also minimized.

Of the river stations sampled, Stations RS05, RS06, RS07, RS11 and RS12 show sedimentenrichment for at least some Site-related constituents. Of these stations, only Stations RS11,RS12 and sometimes RS07 had impairment in terms of benthic density and richness ? •' *toxicity testing results relative to background conditions for these same endpo1nts.fi Tnextent to which data from Stations RS11 and RS12 characterize the northern portion of theChristina River in the Site vicinity is not known.

For the remainder of the study area, based on the weight of evidence of biologicalcollected at specific stations, no impacts to aquatic receptors solely attributable to Site-related constituents can be concluded.

Terrestrial Risk

The Hazard Index Methodology used in this evaluation is intended to be used as a screeningtool and does not provide an accurate analysis of risk. Potential impacts on wildlife fromingesting food, sediment, soil, and water containing a variety of elevated metalsconcentrations cannot be readily predicted using available evaluation technology. Owing tothe number of assumptions which are inherent in the Hazard Index Methodology, thisapproach and results should be used as a screening tool to assess the potential for terrestrialrisk. •

Based on the terrestrial/wetland analysis portion of this EE, several Site-related stationshave been identified that may potentially pose some minor risk to terrestrial wildlife as

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represented by the deer mouse, muskrat, and great blue heron. Minor risk can be definedas "one affecting a specific group of individuals in a population at a localized area and/orover a short period (one generation or less), but not affecting other trophic levels or theintegrity of the population itself (Conover et al, 1985).

None of the measured concentrations of ecological constituents of concern are consideredto pose significant risk or the potential for acute toxic reactions to the three receptors thatwere evaluated. The potential risk from chronic exposure to elevated barium concentrationsfound in soil, sediment, and food at locations where barium concentrations were elevated(i.e., South Disposal Pond and South Disposal site drainageways) is not certain, however itis believed to be negligible. Barium found in the abiotic media at these areas is highly likelyto be in the form of barium sulfate which is the most stable form, due to the oxidizingconditions. Since barium sulfate is essentially nontoxic, the potential for adverse impactsis unlikely. This assessment is supported by Site-specific lexicological data.

High levels of barium found in the roots and rhizomes of spatterdock at the South DisposalPond and South Disposal site wetlands indicate a nonphytotoxic response with respect to thisplant species. The potential risk to muskrat and other wildlife from ingesting large amountsof spatterdock roots and rhizomes is probably negligible owing to the known low toxicity ofbarium, and feeding habits of muskrats in this region. These two factors were input intocomputation of hazard indices for exposure scenarios which also identified limited riskattributable to barium. Barium sulfate is poorly soluble, which contributes to its low toxicity.Hazard indices for all terrestrial and wetland exposure scenarios result in a low potentialfor hazard due to ingestion of barium containing soils, sediments and/or vegetation at theSouth Disposal site, and the South Disposal site pond and wetlands. The extent of thedietary composition of spatterdock for muskrats is unknown, therefore, the overlyconservative assumption that the muskrat diet is primarily (100 percent) composed ofspatterdock over estimates this risk.

Elevated zinc concentrations (0.1 percent and 0.2 percent in sediment and soil) weredetected at the North Disposal site and North Disposal site drainageway. Theseconcentrations are considered likely to have some phytotoxic impacts on the plant

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communities present. Ingestion of soil, sediment, and food with such elevated zincconcentrations is considered unlikely to produce any acute toxic reactions to the deer mouse,muskrat, or great blue heron since zinc is an essential element and can be metabolized andexcreted at some levels.

Chronic exposure to the elevated zinc, barium, lead and chromium concentrations in theNorth. Disposal site and North Disposal site drainageway may result in some negligible orminor impacts based on hazard indices computed. However, elevated levels of theseconstituents on the North Disposal site occur only at limited areas which are characterizedby soils chemistry data from landfill ore material (SGS-6). It is estimated that these areas,which are unvegetated, represent less than 10 percent of the surface area of the NorthDisposal site. Since these areas are unvegetated, they are less attractive to receptors (i.e.,deer mouse), hence reducing the potential exposure.

Given the overall low Hazard Index results (highest Hazard Index value = 1.7) for each ofthe areas evaluated, it appears unlikely that significant impacts to the deer mouse,or great blue heron can be expected to occur as a result of exposure to levels of constitfound at the Site. Any adverse impacts that may be expected to occur at this Site, could beclassified as minor, in that only a few localized individuals are likely to be affected.

CONCLUSIONS

Based on the aquatic exposure evaluation and impact characterization, the central portionof the North Disposal site drainageway from the vicinity of Station AS07 to Station AS09has been impacted by Site-related constituents or activities. This conclusion is based onecological data which have been collected as part of the three-phase RI/FS fieldinvestigation including surface water, sediment chemistry, toxicity testing and benthiccommunity data.

Other portions of the aquatic ecosystem in the Site study area which may be impacted, butyhere insufficient data exist to define the aerial extent of the impact includes the SouthDisposal site wetlands in the vicinity of the berm, ISttMlie CfirfStfha Rfv r ffl thevicinity of

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Stations RS11 and RS12. This conclusion is based on sediment chemistry, toxicity testingand benthic community data collected from these locations.

<~7For the remainder of the study area, based on the weight of evidence of biological data \collected at specific stations, no impacts to aquatic receptors solely attributable to Site-/related constituents or activities can be concluded.

Based on this conservative analysis of risk to terrestrial and wetland wildlife at the Site, itis unlikely that significant impacts to the receptors evaluated will occur under existingconditions and current assumptions. Using overly conservative assumptions, the highesthazard index calculated for all terrestrial and wetland exposure scenarios was only 1.7.

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1.0INTRODUCTION

1.1 BACKGROUND

The Du Font-Newport Superfund Site (Site) is located to the south of the City of Newport,Delaware, and is bisected by the Christina River. The study area for the Site consists of:an operations area (including the CIBA-GEIGY Newport Plant area and the Du Pont HollyRun Plant area); two inactive landfills labeled the North Disposal site and the SouthDisposal site; the associated wetlands; the associated segment of the Christina River; thepotentially impacted groundwater; and a small recreational area (Ballpark) locatedimmediately northwest of the operations area.

As part of the Remedial Investigation/Feasibility Study (RI/FS) process for the Du Pont-Newport Site, Woodward-Clyde Consultants (WCC) conducted a three-phase RemedialInvestigation (RI). This RI included four periods of field activities for the WetlandsInvestigation (Phase I, Phase II, Phase HI, and Supplemental Phase III) for the collectionof surface water, sediment chemistry, and ecological field data in the vicinity of the Site onbehalf of E.I. du Pont de Nemours and Company, Inc. (Du Pont). Collection efforts werein accordance with Work Plans approved by the U.S. Environmental Protection Agency(EPA). Data generated were compiled in a Phase n Wetlands Investigation Report (WCC,1989a), a Phase III Wetlands Investigation Technical Data Summary Report (TDS) (WCC,1990a) and a Supplemental Phase HI Wetlands Investigation Report (WCC, 1991). Inaddition, Christina River surface water quality data and surficial soils data collected priorto the Wetlands Investigation were published in the Work Plan for the Du Pont-NewportSite (WCC, 1988b).

The ecological field data collected in the Christina River and wetlands in the vicinity of theSite during the three-phase wetlands investigation and the 1988 Work Plan were utilized inthe preparation of the reports described above and as input into the EnvironmentalEvaluation (EE) for the Site. This report represents the EE for the Du Pont-Newport Site

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as required in the Comprehensive Environmental Response, Compensation and Liability Ai(CERCLA). This evaluation was prepared in accordance with Risk Assessment Guidancefor Superfund (RAGS), Volume II, Environmental Evaluation Manual (USEPA 1989b), andcomments received from the EPA project team for the Du Font-Newport Site. A draft EEwas submitted to the EPA in July, 1991. EPA written comments on that draft were receivedby Du Pont in September, 1991. Written response was submitted to the EPA by Du Pontin October, 1991.

Several meetings and teleconferences were also conducted in February and March, 1992between EPA and Du Pont and their respective technical consultants and representatives,during which additional comments and resolutions, and specific directives for conductingterrestrial exposure scenarios were received from EPA. The most significant commentsresulted in the following changes to the EE document originally submitted in July, 1991:

• Elimination of the sediment quality triad approach as a tool for evaluatingsediment quality at the stations sampled (Letter from Sturgeon to Karmazyndated March 20, 1992)

• Use of a quantitative approach to the evaluation of terrestrial and wetlandexposure receptors (Finalized in letter from Sturgeon to Karmazyn datedMarch 20, 1992)

• Use of USEPA Water Quality Criteria for the Protection of Aquatic Life asARARs for groundwater seepage (EPA meeting with Du Pont of March 5,1992)

Du Pont is in strong disagreement with this last directive but has satisfied EPA's request inthis document. Du Pont's disagreement is based on the fact that the seepage was collectedat the actual discharge point from the bank surface, it had not been exposed to surficialsediments and the ambient air, and hence, did not possess the geochemical characteristicsattributable to a surface water in a technical sense.

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The EE represents Volume II of the two-volume Risk Assessment for the Newport Site.Volume I is the Human Health Evaluation, which is presented as a separate, companiondocument.

12 OBJECTIVE

The objective of the EE is to utilize data generated during the Wetlands Investigations inconjunction with other data from the RI to identify areas in the vicinity of the Site whichappear to demonstrate environmental impact. In this way, the Feasibility Study can befocused to insure that if any remediation is necessary, it will focus on areas where theenvironmental impacts are greatest.

1.3 SCOPE

The scope of the EE was designed in accordance with the RAGS EE Manual and thenumerous comments by the EPA project team for the Site. The EE document is arrangedinto the following sections:

Section 1.0 Introduction: describes events leading up to preparation of the EE, andthe objective and scope of the evaluation;

Section 2.0 Environmental Setting: describes the regional and local setting in termsof habitats, flora and fauna based on site-specific data collected as part of theWetlands Investigations, and existing data;

Section 3.0 Wetlands Investigation Sampling and Analysis: summarizes samplingplans and rationale for all phases of the Wetlands Investigations;

Section 4.0 Chemical Constituents Characterization: summarizes waste disposalhistory for the Site and results of analytical chemistry data generated in the WetlandsInvestigations;

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Section 5.0 Constituents of Concern: presents toxicity profiles and rationale forselection of constituents of concern;

Section 6.0 Ecological Exposure: defines and evaluates potential routes of exposurefor the Site;

Section 7.0 Impact Characterization: identifies portions of the study area whichpresent the greatest ecological impact;

Section 8.0 Uncertainties and Limitations of Analysis: presents uncertainties andlimitations of the data used in this EE;

Section 9.0 References: lists data sources used in preparation of the EE; and

Appendices: includes selected data tables and information from the three phases ofwetlands investigations:

• Appendix A - Phase II Wetlands Investigation

• Appendix B - Phase III Wetlands Investigation

• Appendix C - Supplemental Phase III Wetlands Investigation

• Appendix D - Sediment Quality Triad Analysis

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2.0ENVIRONMENTAL SETTING

The environmental setting of the Du Font-Newport Site study area is described in thissection. Both a regional setting and a local description are provided. The purpose of thisdescription is to characterize potentially exposed ecosystems and biological populationswhich represent potential receptors for the ecological exposure assessment, which ispresented in Section 6.0.

2.1 REGIONAL SETTING

The Du Font-Newport Site is located in northern New Castle County, Delaware, within theAtlantic Coastal Plain Province, proximal to the Appalachian Piedmont Province. TheCoastal Plain is a relatively flat and low area with elevations not exceeding 100 feet abovemean sea level. The area adjacent to the Delaware Bay is exposed to tidal flooding and ischaracterized by conspicuous tidal marshes. Most of the streams in this zone are tidal orhave a tidal segment. Stream valleys are shallow compared with those of the PiedmontProvince to the north.

The Piedmont Province is an area of diversified relief dissected by narrow and deep streamvalleys with residual high areas rising above the general upland level. The streams descendin rapids or falls from the hard crystalline rocks of the Piedmont to the soft, unconsolidatedsediments of the Coastal Plain. The narrow zone which separates the Piedmont and CoastalPlain Provinces is called the Fall Zone, which divides the area of predominant erosion(Piedmont) from the area of predominant deposition (Coastal Plain). The Christina Riverdrainage basin is considered the dividing line of the Coastal Plain and the PiedmontProvince (Lee et al, 1981; Kalbacher, 1991)..

The Christina River is a major tributary of the Delaware River, and has a drainage basinof about 565 square miles. Approximately 166 square miles of this basin is in northern New

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Castle County, and the remaining 399 square miles is in Pennsylvania and Maryland(Rasmussen et al, 1957).

The Christina River's northern tributaries originate in the Piedmont, while the southernportion of the drainage is in the Coastal Plain. The headwaters of this river are in southcentral Chester County, Pennsylvania and northeast Cecil County, Maryland.

The Christina River exhibits semi-diurnal tides from its confluence with the Delaware Riverupstream to Smalley's Pond, a 19-acre impoundment created by a dam at approximatelyriver mile 15. Located at river mile 7.5, the Du Font-Newport Site is approximately midwaybetween the mouth of the river and the head of tide at Smalley's Pond dam.

Although the tidal portion of the Christina River runs through developed residential andindustrial areas, such as Wilmington and Newport, it also drains areas of extensive'freshwater tidal marsh, such as Churchman's and Newport Marshes. Much of the ChristinaRiver marshes, especially Newport Marsh, have been lost and or degraded by fillingdevelopment. A comparison of topographic maps dated 1948 (Figure 1) and 1987 (Fig2) show that during that 39-year period, approximately 500 acres of mapped tidal marshwere drained and filled, mainly for the construction of the Route 95/295/141 interchanges,just south of the present day Christina River. During this period the course of the river wasalso changed. An approximately 1.5 mile long oxbow of the river was cut off and filled.This area is now the Route 295/95 interchange.

22 STUDY AREA DESCRIPTION

The Christina River bisects the Site study area into north and south portions. The northernportion includes the North Disposal site, and associated wetlands on the north side of theChristina River, the Du Pont Holly Run Plant area, the CIBA-GEIGY Newport Plant area,and the Ballpark. The North Disposal site is located on a seven-acre parcel bounded on thewest and north by the Du Pont Holly Run Plant and the CIBA-GEIGY Newport Plant,respectively, on the southeast by the Christina River, and on the southwest by ChristinaRiver tidal marsh. The southern portion of the Site study area consists of a 45-acre parcel

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of land owned by Du Pont on the south side of the Christina River, opposite the CIBA-GEIGY and Holly Run plants, which includes the South Disposal site and associatedwetlands.

Land use surrounding the Site is varied. To the north of the Site, land use is primarilyresidential. The majority of the remaining property north of the Christina River is primarilyfreshwater emergent wetlands. The area adjacent to the south side of the river consists ofa sizeable expanse of former emergent wetlands now covered by auto salvage yards andrimmed by a residential/commercial strip along Old Airport Road.

2.2.1 North Disposal Site

The North Disposal site was used for the landfilling of general refuse and process wastesfrom 1902 until 1974, when it was covered with about 2 to 3 feet of clayey soils. The NorthDisposal site is primarily covered with maintained grass and rimmed with small trees andother vegetation. A drainageway which empties into the Christina River surrounds thenorthern and western boundaries of the North Disposal site. Except in areas sloping towardthe drainageway, the surface elevation for most of the North Disposal site is at an elevationof 20 to 25 feet, and at least 10 feet above the shallow water table. Buried waste materialswithin the North Disposal site are a potential contaminant source for soils, sediment andsurface water in the surrounding area.

222 South Disposal Site

An elevated 15-acres of the southern portion of the Du Font-Newport Site study area isknown as the South Disposal site, which was used for the landfilling of insoluble residuesof zinc and barite ores. These wastes were pumped as a slurry through a pipe under theChristina River. Earthen dikes and berms were constructed to contain this material. TheSouth Disposal site was operated from 1902 to 1953. In 1973, the Delaware Departmentof Highways deposited approximately 130,000 cubic yards of soil from the construction ofState Route 141, covering the South Disposal site with an average of three feet of variable

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~ »soil. (For a summary of the disposal history of the North and South Disposal sites seeSection 4.0, Chemical Characterization).

The South Disposal site is currently moderately to heavily vegetated. The previouslandfilling operations have resulted in grade elevations ranging from a high of aboutelevation 30 feet at the extreme northern corner, to about elevation 2 feet at the southernend of the landfilled area. A dike traverses the center of the 45-acre southern tract in an

v east-west direction, curving in a northerly direction near the eastern and western boundariesof the South Disposal site. The dike has steep side slopes and an approximately 25-footwide crest, with a typical elevation of about 12 to 13 feet above mean sea level. A breachexists in the dike near its southwest corner. There is a triangular wedge of wetlands and asmall (one acre) surface water pond (South Disposal site pond) between the dike and theSouth Disposal site (Figure 3). Sequential aerial photographs from 1937, 1946, 1948 and1968 show that a breach developed in the berm surrounding the western cell of the SouthDisposal site, resulting in migration of Disposal Site materials into adjacent wetlands.

Approximately 20 acres of the southern portion of the Site study area outside the diked arRTis fresh water emergent wetlands. Historically, a series of ditches were cut through thiswetlands area in order to route drainage to the river (primarily toward the east). Theseditches continue to provide some drainage, but the water from this ditch system now reachesthe Christina River via a tidegate located at the western end of the northern propertyboundary with the Christina River. This change in drainage direction was apparently causedby rechannelization of the river and fill operations associated with the state Route 141construction.

223 Christina River

The width of the Christina River between the North and South Disposal sites ranges fromapproximately 160 to 330 feet. The tidal influence of the Delaware Bay extends past theDu Font-Newport Site to approximately 15 miles upstream from the confluence of theChristina and Delaware Rivers. According to the National Oceanic and AtmosphericAdministration (NOAA), the mean tidal range of the Christina River at Wilmingtpn,

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approximately five miles downstream of the Newport Site, is 5.7 feet (NOAA, 1989). Thisagrees with the daily tidal fluctuations observed to occur over an average of between 5 and6 feet by WCC during one month of continuous tidal monitoring during June to July 1987.

There are three main sub-drainage basins that contribute to the main stem of the ChristinaRiver. The headwater area of the Christina River drains an area of about 79 square miles.The White Clay Creek, which joins the Christina River about 2500 feet upstream of the Site,contributes the major portion of the freshwater flow volume at the Site. It drains an areaof approximately 108 square miles, much of which is in Chester County, Pennsylvania. RedClay Creek, the principal tributary to White Clay Creek, has a drainage area of 54 squaremiles, 33.3 of which are in Pennsylvania. Both of these streams drains areas of bothindustrial and agricultural land use (Rasmussen et al, 1957). In total the drainage basinarea contributing flow in the Christina River at the Site is approximately 241 square miles(Rasmussen, et al, 1957).

There are a variety of additional inputs into the Christina River in the vicinity of the DuPont-Newport Site. Numerous wetland drainages empty into the Christina River, includingchannels draining the North and South Disposal sites. Other inputs include groundwaterseeps, highway runoff, municipal stormwater outfalls and permitted outfalls. All of theseinputs contribute to the water quality of the Christina River in the Site vicinity.

The State of Delaware Surface Water Quality Standards (as amended February 2,1990) listthe designated uses of the tidal portion of the Christina River basin as industrial watersupply, secondary contact recreation, and fish, aquatic life, and wildlife. The open watersof the Christina River in the vicinity of the Du Font-Newport Site have been characterizedas estuarine and oligohaline (salinity range between 0.5 to 5 parts per thousand, ppt) by theU.S. Fish and Wildlife Service (USF & WS). This designation may be accurate duringsummer months, when freshwater discharges to the river are reduced and evaporation ishigh, allowing the salt water wedge from the Delaware River to push further upstream.During WCC aquatic field sampling activities, which all took place during autumn, the riverwas generally at or below a salinity of 0.5 ppt.

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Using the USF & WS classification system (Cowardin et al, 1979), a salinity below 0.5 pptwould result in characterizing the river in the Site vicinity as tidal riverine. Due to the riseand fall of the tides, some areas of the Christina River riverbank consist of intertidalmudflats which support the growth of nonpersistent emergent plants. Dominant riverineemergents in the Site vicinity are arrow-arum (Peltandra virginica). spatterdock (NupharvariegatunV). and pickerelweed (Pontederia cordata). Tidal riverine emergent wetlandsappear as unvegetated mudflats during winter and early spring due to the rapiddecomposition of the above ground vegetation after the growing season.

Based on studies conducted by WCC, the substrate of the Christina River in the Newportarea is variable. The sediments encountered range from silts and muds in depositionalareas, to predominately sandy in erosional areas, to areas adjacent to the Newport Sitewhich are underlain by rubble, rip-rap and various types of urban refuse. In general,subsurface sediments (below 6-12 inches) are composed of firm, grey clayey sediments.

Twenty species of fishes were collected by WCC in the tidal Christina River in theof the Du Font-Newport Site and field reference stations. Thirty-two species of fishbeen reported as occurring in the tidal portion of the Christina River by the DelawareDepartment of Natural Resources and Environmental Control (DNREC) (1989). Thesespecies are listed in Table 1.

The benthos of tidal freshwater areas has been characterized by Towns (1937) as beingcomposed of freshwater snails, the oligochaetes Limnodrilus .gpjj., chironomids, and theamphipod Gammarus fasciatus. Other studies have shown that freshwater tidal marshmacrobenthos are dominated by tubificid oligochaetes and larval chironomid insects (Diaz,1977). The benthic invertebrates of the Christina River and associated wetlands also followthese patterns. Field surveys of the benthic communities conducted by WCC in 1989 found27 benthic taxa in the Christina River (WCC, 1990a). Similar surveys conducted in 1990found 31 taxa in the river (WCC, 1991). These taxa included coelenterates, turbellarians,nemerteans, nematomorphans, annelids, crustaceans, hydracarina, insects, and molluscs. Alist of macroinvertebrates collected in the study area is presented in Table 2.


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2.2.4 Wetlands

According to Section 404 of the Federal Clean Water Act, wetlands are those areas that areinundated or saturated by surface or ground water at a frequency and duration sufficient tosupport, and that under normal circumstances do support, a prevalence of vegetationtypically adapted for life in saturated soil conditions. The bulk of tidal freshwater marshflora consists of: (1) broad-leaved emergent perennial macrophytes (spatterdock, arrow-arum, pickerelweed, arrowheads); (2) herbaceous annuals (smartweeds, tearthumbs,burmarigolds, jewelweed, giant ragweed, water-hemp, water-dock); (3) annual and perennialsedges, rushes and grasses (bulrushes, spike rushes, umbrella-sedges, rice cutgrass, wild rice,giant cutgrass); (4) grasslike plants or shrub-form herbs (sweetflag, cattail, rosemallow,water parsnip); and (5) hydrophytic shrubs (button bush, waxmyrtle, swamp rose) (Odumet al, 1984).

Vegetation

The Delaware Coastal Management Program defines the wetlands in the Site vicinity aseither transition marsh, arrow-arum or pickerelweed marsh or lost marsh. Plant speciesobserved growing on or near the North and South Disposal sites by WCC personnel includeduckweed (Lemna sp.). water lilly (Nuphar variegatum). arrow arum (Peltahdra virginica).woolgrass (Scirpus cyperinus). sedges (Carex jspp..), soft rush (Juncus effusus). bur-reed(Sparganium eurycarpem). jewelweed (Impatiens sp.). common reed (Phragmites australis).northern arrowwood (Viburnum recognitum). reed canary grass (Phalaris arundinacea),smartweed (Polygonium sp.). honeysuckle (Lonicera sp.). and raspberry (Rubus sp.). Plantspecies which have been identified at the Site and those which may also be expected tooccur in nontidal and tidal freshwater marshes are presented in Table 3.

Wetlands in the vicinity of the Du Font-Newport Site have been mapped by the USF &WS's National Wetlands Inventory (NWI). As stated previously, the NWI mapping of theSite area indicates that the open waters of the Christina River are classified as estuarine andoligohaline. The NWI mapping also indicates that the wetlands area adjacent to the NorthDisposal site is estuarine intertidal emergent wetlands dominated by narrow-leaved

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persistent wetlands,plants (i.e. Phragmites australis). A field reconnaissance was conductedto verify the extent of wetlands in the vicinity of the North Disposal site as presented in theNWI maps. Based on the WCC reconnaissance of this area, the extent of wetlands presentin the vicinity of the North Disposal site is generally as presented on the NWI map, butdifferences were identified in the wetlands type present. As shown on NWI maps, narrow-leaved persistent emergents, (e.g.f Phragmites australis) dominate the immediate vicinity ofthe North Disposal site (i.e. the drainageway which surrounds the site). However, much ofthis wetlands is predominated by arrow-arum (Peltandra virginica) (WCC, 1990a). Arrow-arum is a cosmopolitan species growing throughout the intertidal zone of many freshwatertidal marshes of the east coast (Odum et al, 1984). It is referred to as a broad-leaved, non-persistent species, which represents a different wetlands type than shown on the NWI map.

A field reconnaissance was also conducted to verify the extent of NWI mapped wetlands inthe vicinity of the South Disposal site. Based on the NWI mapping, wetlands types presentadjacent to the South Disposal site include 14 acres of estuarine emergent and three areasof palustrine open water. Based on the reconnaissance, the total wetlands area presejthis southern portion of the Site study area is approximately 21 acres, including 20 acre!estuarine emergent wetlands and one acre of open water (WCC, 1988a).

The four-acre difference between the NWI acreage and that determined by WCC isprimarily due to the presence of additional wetland areas which have developed within thediked area of the South Disposal site. This diked area maintains a small open water areamapped by the NWI (the South Disposal site pond). WCC observations of this area indicatethat most of the three acres previously mapped as open water have now been vegetated withemergent wetlands species. As is the case over the -remainder of this area, the emergentwetlands is dominated by common reed (Phragmites australis). The extent of these wetlandareas are shown in Figure 3.

Benthic Macroinvertebrates.*•*

"* Benthic fauna collected in the wetlands include most of those forms found in the river, plusa greater diversity of insects and annelids (Table 2). Within the marsh, aquatic insects and

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benthic invertebrates make up an important component in the diets of omnivorous fishes.Benthic fauna (oligochaetes, chironomid larvae) form a major portion of the diets of benthicfeeding fishes such as catfish, striped bass, carp, perch, eels, and cyprinid minnows. (Odumet al, 1984).

Fish

The benthos and plants of the freshwater marsh and associated waters provide year-roundfood and shelter for adults and juveniles of resident fish species. Tidal freshwater marshesalso serve important roles as nursery grounds and important habitat for the young andjuveniles of resident, as well as non-resident species. These areas are important as nurserygrounds because they are rich in food and provide some protection from predators. (Odumet al, 1984).

The three families with the most species and individuals in tidal freshwater are the cyprinids(minnows, shiners, carp), centrarchids (sunfishes, crappies and bass) and ictalurids(catfishes). While a large proportion of the catfish and sunfish populations in a given areamay extend into the tidal freshwater habitats, the minnows, as a group, are much moreabundant in the Fall Zone in non-tidal habitats. (Odum et al, 1984). Species of freshwaterfishes found in tidal freshwaters generally occupy lentic habitats, such as lakes, ponds andriver backwaters, in non-tidal freshwaters.

Fishes are important components of the freshwater tidal and non-tidal marshes in that theyserve an important function in transferring energy along the food web. Despite theabundance of algae and plant detritus in tidal freshwater habitats, few species of fish feeddirectly on these resources with the exception of the gizzard shad, silvery minnow, goldenshiner and hogchoker. The abundant supply of detritus and algae are made available to fishthrough intermediate steps in the food chain, specifically through small Crustacea and insectlarvae of the benthos (Odum et al, 1984). These fishes are in turn consumed by piscivorousfishes, birds and mammals, thereby completing the food chain.


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Reptiles and Amphibians

Reptiles and amphibians also comprise an important component of the food chain infreshwater tidal and non-tidal wetlands. Amphibians and reptiles are found in freshwaterlakes, ponds, streams, rivers, swamps and marshes. No species of reptile or amphibian aresolely confined to tidal freshwater wetlands. Reptiles captured during WetlandsInvestigations were limited to turtles and were generally incidental by-catches coincidentwith fish collection efforts. These reptiles include the stinkpot (Stenothaerus odoratus),common snapping turtle (Chelydra serpentina). red-eared slider (Pseudemys scripta), andthe eastern painted turtle (Chrysemys picta). No amphibians were collected, but severalunidentified frogs were observed. Since it was beyond the scope of the current effort toperform a herpetological inventory of the Site, data collected throughout the State ofDelaware were used to characterize regional fauna. A list of reptiles and amphibians whichhave been collected in freshwater wetlands throughout Delaware and which may be presentat the Site (providing suitable habitat exists) is presented in Table 4.

Birds

Only a few species of birds were observed in the river and wetlands associated with theNorth and South Disposal sites during field efforts. These included great blue heron,mallard, starling, crow, and black-crowned night heron. Osprey have been observed inWhite Clay Creek and an adult bald eagle was observed in November 1990 in Churchman'sMarsh, approximately 1.5 miles upstream from the Site. Although no bird studies have beendone in the wetlands adjacent to the Site, two bird surveys were conducted by the DelmarvaOrnithological Society (DOS) in Churchman's Marsh during 1965 to 1966 and 1980 (Hess,1983; and West and Klabunde, 1977). During the 1965 to 1966 study, 47 censuses wereconducted. One hundred and sixty-seven species were recorded, with 112 species havingbeen sighted on at least three occasions. During this study, Churchman's Marsh was dikedoff from the Christina River and White Clay Creek and became freshwater impoundment.The DOS described this area as an important feeding area for herons and ibis, and a goodbreeding ground for waterfowl (West and Klabunde, 1977).

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During the bird population study conducted in 1980, 52 censuses were conducted. Onehundred and fifty-three species (plus four unidentified) were reported (Hess, 1983). Duringthis census, 20 species not reported during 1965 to 1966 were recorded. Hess (1983) foundthat during the time between the two surveys 35 species of birds decreased in numbers ofindividuals observed and percent frequency of occurrence, while 17 species increased. Thisstudy claimed that Churchman's Marsh had deteriorated as a bird habitat, especially forwater and field birds, Hess attributes this deterioration to: (1) the conversion of theimpoundment to a tidal pool from the break of the Christina River dike; (2) expandedindustrial use in the western portion of the Churchman's Marsh study area; (3) modificationsto and increased use of Interstate 95 (which borders the marsh) and its accompanying airand noise pollution; and (4) water pollution from upstream sources. Evaluation of historicalaerial photographs suggest that changes in the marshland and river hydrology caused by roadconstruction probably accounts for the majority of habitat changes rather than industrialactivity in the area.

Table 5 lists 139 species of birds commonly recorded during the two DOS surveys. As theywere seen in Churchman's March, approximately 1.5 miles from the Site, some of thesebirds might be expected to use the wetlands, river or associated uplands at the Site forfeeding, nesting, resting, and/or breeding.

Mammals

Another component of the freshwater marsh community is made up of mammals. Basedon field signs of mammal utilization the following mammals may occur in the wetlands nearthe Site: white-tailed deer; eastern cottontail; deer mouse; muskrat; fox; and beaver. Table6 lists additional mammals which are expected to occur in freshwater wetlands (Odum etal, 1984), and which may utilize wetlands areas of the Site.

2.2.5 Terrestrial Habitats

Terrestrial habitats which occur in the Du Font-Newport Site study area are limited to theactual area of the North and South Disposal sites, where the landfilling and dike building

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took place. The upland portion of the North Disposal site which supports terrestrial habitatis approximately seven acres of mainly field grasses, which is rimmed with trees and otherupland vegetation. Field signs of wildlife utilization of the disposal sites include that ofwhite-tail deer (Odocoileus virginianus) and eastern cottontail rabbit (Sylvilgus floridamis).

The upland portion of the South Disposal site that supports terrestrial habitat is theapproximately 15 acres of previously landfilled area, and the dike or berm which surroundsit. This area is covered with common reed, various low herbaceous plants, and variousspecies of upland trees, such as black locust. Signs of wildlife utilization observed at theSouth Disposal site were similar to those at the North Disposal site. Empty shotgun shellsfound at various locations on the South Disposal site suggest that limited illegal hunting ofsmall game may occur here.

2.2.6 Sensitive Habitats

Data on potentially sensitive habitats including threatened and endangered species habwithin three miles of the Site have been requested from the DNREC Natural HeritProgram and the Endangered and Nongame Species Program. The U.S. Fish and WildlifeService has stated that "except for occasional transient individuals, no Federally-listed orproposed endangered or threatened species are known to exist in the project impact area"(Personal communication with A. Moser, September 25, 1991). Based on a reconnaissanceperformed by DNREC, no rare, endangered or threatened plant or animal species wereobserved on-Site (Personal communication with K. Kalbacher, October 7, 1991).

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3.0WETLANDS INVESTIGATION SAMPLING AND ANALYSIS

3.1 CHRONOLOGY

In this section, components of the sampling and analysis plans which directed the WetlandsInvestigation field efforts are described. The purpose of this section is to summarize thethree data collection efforts which form the data sets upon which the EE is based. Thissection also demonstrates the rationale behind data collection efforts for each phase, whichwas typically based on the findings of the previous phase. The objectives, scope and resultsof the Phase I river study, the Phase II Wetlands Investigation, Phase III WetlandsInvestigation, and the Supplemental Phase III Wetlands Investigation are summarized below,as well as a description of ecological endpoints of the various analyses which wereconducted.

3.2 DATA COMPARISONS

3.2.1 Ecological Endpoints

An integral part of the development of the overall sampling and analysis plans for theDu Font-Newport Site involved identification of ecological endpoints against which observedenvironmental characteristics could be calibrated. Environmental data generated in theWetlands Investigations have been incorporated into this EE, which in turn provides inputto the decision making process for Site characterization and remediation. The results of theEE that constitute input into the decision making process are descriptions of therelationships of pollutants to ecological endpoints. There are two types of ecologicalendpoints: assessment endpoints and measurement endpoints.

Assessment endpoints are environmental characteristics, which, if they were found to beaffected to a sufficient extent, could suggest the need for remediation. Measurementendpoints are quantitative expressions of an observed or measurable effect of the impact;

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it is a measurable environmental characteristic that is related to the valued characteristicchosen as an assessment endpoint (USEPA, 1989b). The assessment endpoints for theDu Font-Newport Site EE were: reduced density and diversity of benthic macroinvertebratesin Christina River and wetlands sediments; elevated tissue levels of heavy metals in fish andwetlands plants; and toxicity of sediments to fish and invertebrates. Measurement endpointsfor this evaluation included: the density and diversity of benthic macroinvertebratesinhabiting Christina River and wetlands sediments; metals levels in fish tissues (whole bodyand fillets); metals levels in wetlands plants; percent survival and growth of larval fatheadminnows (Pimephales promelas). water fleas (C/ iaphina dubia). midge larvae(Chifonomus tentans) and amphipods (Hyalella azteca.- trxposed to either Christina Riverand wetlands sediments or sediment elutriates; Target Analyte List (TAL) metals levels inwetlands and Christina River surface water; and TAL metals levels in wetlands sediments.For a discussion of how these endpoints relate to a description of ecological impacts, seeSections 6.0 and 7.0.

322 ARARs and Guidelines

Several regulatory standards and requirements were considered in the evaluation ofpotential constituents of concern at the Du Font-Newport Site. . Where no appropriatestandards or criteria were available, other reference levels, based on the literature or fielddata, were used as a basis for comparison. No state or federal criteria for acceptable levelsof metals in sediments currently exist. However, sediment guidelines compiled by severalregulatory agencies are available. Five data sets for sediment quality guidelines, along withsediment metal concentrations measured at reference Station RS15, are summarized inTable 7. None of these are promulgated criteria,- but are guidelines that have beendeveloped as screening tools and to focus the effort of development of sediment qualitycriteria. Of the sediment quality guidelines, the USEPA TVG's (described below) wereused as a specific screening tool in the evaluation of potential ecological constituents ofconcern.

It should be noted, that all of these guidelines were developed using different assumptionsand are pertinent to only some systems. Therefore, some of these guidelines may not

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directly applicable to the Site setting. For example, the biological effects guidelines (ER-L,ER-M) prepared by the National Oceanic and Atmospheric Administration (NOAA) (Longand Morgan, 1990) are based mainly on estuarine investigations. In the absence ofappropriate criteria however, the EPA project team requested that these guidelines also beused for comparative purposes in sediment quality evaluation for the Du Font-Newport Site.

The EPA has authority to pursue the development of sediment criteria in surface waters ofthe United States under Sections 104 and 304(a)(l) and (2) of the Clean Water Act. TheEPA Office of Water Regulations and Standards published TVGs for the evaluation ofcontaminant levels in sediment in the National Perspective on Sediment Quality (USEPA1985). These TVGs were developed as a first step in establishing sediment criteria.

Guidelines for classifying sediments of Great Lakes Harbors were developed by the EPAand U.S. Army Corps of Engineers to help assess the impact of freshwater and marinedredged materials. These guidelines are shown in Table 7. ,

The Wisconsin Department of Natural Resources has compiled a set of interim criteria todetermine the suitability of dredged material for in-water disposal. Dredged materialscannot be disposed of in the State of Wisconsin if they exceed these criteria by a specifiedamount (Wisconsin Department of Natural Resources, 1985). The criteria are included inTable 7.

The Ontario Ministry of the Environment (OME) have developed sediment managementguidelines based on a comparison of several techniques and reported three guidelines: (1)the no effect level; (2) the lowest effect level; and (3) a limit of tolerance level. Thesesediment quality criteria are based on overt toxicity to benthic invertebrates and do notconsider bioaccumulation and subsequent effects on longer-lived species. OME guidelinesare presented in Table 7.

The NOAA examined a wide variety of methods and approaches to measuring the adversebiological effects of chemical contamination of sediments in coastal marine and estuarineenvironments. The chemical concentrations observed by the different methods to be

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associated with biological effects were sorted. The lower 10 percentile in the data wasidentified as an Effects Range - Low (ER-L), a concentration at the low end of the rangein which effects had been observed, and the concentration approximately midway in therange of reported values associated with biological effects was identified as the EffectsRange - Median (ER-M). These guidelines are also shown on Table 7.

In addition to promulgated and non-promulgated criteria, applicable or relevant andappropriate environmental stpnnes have also been considered in the environmentalevaluation of the Du Font-New; i Site relating to wetlands and endangered or threatenedspecies. Regulations requiring permits for the discharge of fill into wetlands have beendeveloped pursuant to Section 404 of the Clean Water Act. Similar permitting requirementshave been developed pursuant to the Delaware Regulations Governing the Use ofSubaqueous Lands (DNREC 1991). For this reason, an understanding of approximatewetland boundaries on the Site is necessary. Approximate wetlands boundaries on and inthe vicinity of the Site have been defined (Figure 3, Section 2.2.2).

In response to the Endangered Species Act, the potential for endangered or threatenedspecies to occur on or in the vicinity of the Site has been addressed (Section 2.2.4). TheU.S. Fish and Wildlife Service has stated that "except for occasional transient individuals,no Federally-listed or proposed endangered or threatened species are known to exist in theproject impact area" (personal communication with A. Moser, September 25,1991). Basedon a reconnaissance performed by DNREC, no rare, endangered or threatened plant oranimal species were observed on-Site (Personal communication with K. Kalbacher, October7, 1991).

Surface water metals concentrations were compared to chronic and acute DNREC and EPAWQC (Table 8) (USEPA, 1986 and DNREC, 1990). These promulgated WQC weredeveloped under the authority of the Clean Water Act. Criteria for TAL metals areincluded in Table 8. DNREC has promulgated some of the federal WQC as state waterquality standards. Where necessary the WQC were adjusted for Site-specific water hardnessas described in Section 4.4. If either the acute or chronic WQC were exceeded in at least

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one water sample from a station the metal was placed on the list of potential constituentsof concern for the Du Font-Newport EE.

3.3 PHASE I RIVER STUDY

The Work Plan for the Phase I river study was submitted as a portion of the RI/FS WorkPlan and described surface water and sediment investigations to be performed in theChristina River in the vicinity of the James Street Bridge. The investigation was conductedin August 1987 and results were complied in the Work Plan RI/FS Appendices C and Dsubmitted to the EPA on July 28, 1988 (WCC, 1988b).

3.3.1 Objectives

The objectives of the Phase I river study were to measure the sediment levels of barium,cadmium, chromium and zinc with depth in the sediments of the Christina River in the Sitevicinity and to measure levels of TAL metals in river water for one complete tidal cycle.

3.3.2 Scope /

The scope of the Phase I river study included collection of sediment cores from the surfaceto a depth of about three feet at six stations in the Christina River; and hourly collectionof river water samples from the James Street Bridge for one complete tidal cycle. Allsurface water and sediment samples were analyzed for the TAL metals. Additionalphysicochemical parameters such as sediment grain size and percent organic carbon weremeasured on sediment samples.

3.3.3 Results

Results of the Phase I field effort and laboratory analyses are summarized here. The dataare discussed in more detail by media in Section 4.0, Chemical ConstituentsCharacterization.


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High sediment concentrations of barium, cadmium and zinc were measured in samples fromstations located in the river adjacent to the North Disposal site. The surface waterchemistry showed high concentrations of various metals including aluminum, barium,cadmium, chromium, lead, iron and zinc in unfiltered surface water samples collected fromthe James Street Bridge over the continuous tidal cycle. When these samples were filtered,concentrations of the metals dropped substantially, in most cases, to levels below WQC,indicating that most were present in paniculate (bound) form and hence, was probably notbioavailable. Barium concentrations fluctuated inversely with tidal cycle; that is, theconcentrations of barium were highest during low tide.

3.4 PHASE II WETLANDS INVESTIGATION

The work plan for the Phase II Wetlands Investigation was submitted as a portion of theRI/FS Work Plan and described aquatic biological investigations to be performed in theChristina River and wetlands associated with the North and South Disposal sites (WCj1988b). The investigation was conducted in August of 1988 and results were compilethe Phase II Wetlands Investigation Report submitted to the EPA on March 23,1989 (WCT1989a).

3.4.1 Objectives

The objectives of the Phase II Wetlands Investigation were: to better define the potentialimpact to the aquatic resources that occur in the wetlands; to obtain sufficient data toestimate the extent to which Site target parameters (zinc, barium, and cadmium) haddispersed in the sediments of the Christina River and the wetlands associated with the Site;and to generate data for use in evaluating the on-site biological pathway for chemicalconstituents known to occur at the Site (WCC, 1989a).

3.42 Scope

The scope of the Phase II Wetlands Investigation included: defining the extent of wetlandhabitats at the Site; collecting existing biological data on the Christina River and

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wetlands associated with the Site to define indigenous biological populations in the vicinityof the study area; and preparing a field sampling program for collecting wetlands andChristina River sediments and surface water from the wetlands. Fish tissue collections werealso attempted from open water areas in the vicinity of the North and South Disposal sites,but were unsuccessful.

The extent of wetlands on the Du Font-Newport Site was determined by consultingUSF & WS NWI maps, the Delaware Coastal Management Program, and by conducting afield reconnaissance. Collecting existing biological data to define indigenous biologicalpopulations was accomplished by contacting federal, state and county offices, local privategroups and independent consultants.

The sampling consisted of collecting Christina River sediment at six locations (designatedby EPA), wetlands sediments at nine locations, and wetlands surface water at six locations(Figure 3 and 4). The Phase II Wetlands Investigation Sampling Plan is presented hiTable 9. As agreed upon by the EPA, all surface water and sediment samples wereanalyzed for the TAL metals in addition to a variety of physical and field parameters.

/

3.4.3 Results

Results of the Phase II field effort and laboratory analyses are summarized here. The dataare discussed in more detail, by media, in Section 4.0, Chemical ConstituentsCharacterization.

Most of the wetlands sediment samples exceeded EPA Threshold Value Guidelines (TVGs)(USEPA, 1985) for arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury,nickel and zinc. It should be stressed that these TVGs are just guidelines and not standardsor criteria. (See Section 5.2 for description of reference levels and regulatory standards.)Most of the Christina River sediment samples exceeded TVGs for arsenic, chromium, iron,lead, manganese, nickel and zinc.

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For some metals higher dissolved concentrations compared to total surface waterconcentrations were observed. The specific reason for this was not determined. The acuteDNREC and EPA water quality criteria for the protection of aquatic life (WQC) for lead,iron, and zinc were exceeded in some wetlands surface water samples (USEPA, 1986;DNREC, 1990). In addition, aluminum exceeded the chronic criterion in a few wetlandsurface water samples.

3.5 PHASE III WETLANDS INVESTIGATION

Subsequent to review of the Phase II Wetlands Investigation Report by EPA (WCC, 1989)and a meeting held between the EPA, Du Pont and WCC on May 2, 1989, an agreementwas reached that additional study of the Christina River and wetlands adjacent to the Northand South Disposal sites was needed to supplement and clarify data collected duringPhase II, and further assess the environmental impacts and ecological risks associated withthe Site. Therefore, WCC prepared a Phase III Wetlands Investigation Work Plan1989b). This Work Plan was accepted by the EPA and the Phase III Wetlands InvestigEwas conducted in August and December of 1989. Results were presented in a Phase"Wetlands Investigation Technical Data Summary Report (TDSR) submitted to the EPA onJanuary 19, 1990 (WCC, 1990a).

3.5.1 Objectives

The overall objective of the Phase III Wetlands Investigation was to collect additional datafor use in assessing the biological impacts associated with the Site, and to supplement andclarify some of the data collected in the Phase II study. These data were to be used toevaluate the relative toxicity of Christina River sediments and wetlands sediments to aquaticbiota.

Surface water chemistry samples were collected to provide clarification regarding theconcentrations of total and dissolved metals found in the Phase II Investigation and toobtain additional data from the wetlands area near the North Disposal site. Sediment forchemical analyses was collected to obtain data regarding the distribution of the metalsJj i

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sediments downstream of the Du Font-Newport Site; to obtain additional data regardingmetals concentrations near the North Disposal site; and to define the chemistry of sedimentscollected for toxicity and benthic community analyses. Sediment for toxicity testing wascollected to determine potential effects of sediment chemistry on biota inhabiting the NorthDisposal site pond (a slight erosion depression) and lower drainageway, the South Disposalsite pond and drainageway, and the Christina River in the vicinity of the Du Font-NewportSite. A survey of benthic macroinvertebrates was conducted to assess the relative ecologicalhealth of benthic communities in the Site vicinity. Fish were collected and analyzed aswhole body samples to determine what metals, if any, are being accumulated by specieswhich inhabit the White Clay Creek and Christina River.

3.5.2 Scope »

As agreed upon by the EPA, the scope of the Phase III Wetlands Investigation involved: thecollection and analyses of surface water and sediment for TAL metals and sediment physicalparameters; the collection of sediment to be used in toxicity testing; the collection of benthicmacroinvertebrates to assess benthic community structure; the collection of biological tissuesfor TAL metal analyses; and a verification of the wetlands boundaries at the North Disposalsite. The Phase III Wetlands Investigation Sampling Plan is presented in Table 10.

3.53 Results

Results of the Phase III field effort and laboratory analyses are summarized here. Data arediscussed in more detail by media in Section 4.0, Chemical Constituents Characterization.

The Phase III Wetlands Investigation found that Christina River sediments contained levelsof chromium, iron, and manganese above the TVGs at all sampling locations. Sedimentsfrom Station RS06, downstream from the Site, contained the highest levels of arsenic, iron,lead, nickel, and zinc of any river station. Sediments from the wetlands stations had somehigh levels of cadmium, chromium, copper, iron, lead, manganese and zinc. Sediments fromStation AS07, the North Disposal site pond, contained the highest levels of arsenic,cadmium, copper, mercury and nickel of any wetlands station. Sediments collected in the

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South Disposal site wetlands had levels of cadmium, chromium, copper, iron, mercury,manganese, nickel, and zinc above the TVGs.

Toxicity testing of river sediment elutriates showed that for fathead minnows survival at allriver stations was not significantly different than survival in the field reference station(RS04). Minnow survival in elutriate from reference Station RS04 and test Station RS10was significantly different than that of the culture water control. Minnow growth was notsignificantly different from that of reference Station RS04 or the culture water control.Minnows and water fleas exposed to elutriate from Station AS07 suffered 100 percentmortality, but statistical tests showed that survival for both species at all other wetlandsstations was not significantly different than the culture water control.

Toxicity testing of river sediment elutriates showed that for water fleas, Station RS07, with100 percent mortality, was the only station which produced significantly different survivalfrom the culture water control.

As in the Phase II study, some wetlands surface water sample data showed dissolved levelsof barium, calcium, cobalt, magnesium, potassium, and sodium higher than total metalslevels. Again, the reason for this was not determined. Water collected at Station AW05(sediment sampling Station AS07) contained dissolved levels of cadmium, lead and zincexceeding the WQC. Water from Station AW03 had levels of lead and iron exceedingcriteria.

Benthic sampling revealed that most taxa recovered from the Christina River and WhiteClay Creek are common and widely distributed in freshwater habitats of North America.River samples were dominated by tubificid oligochaetes and chironomid larvae. Densitiesfor river stations were typical for tidal freshwater benthos. Highest densities occurred at theupstream control station, lower densities occurred in the Site vicinity and downstreamstations. Wetlands fauna included most forms found in the river, and a greater diversity ofannelids and insects. The highest benthic density occurred at Station AS01, the SouthDisposal site pond, which also had a different community structure than any other station.

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Thirty-one samples of nine species of fish were collected in sufficient quantities to performTAL metals analyses of fish tissues. Whole body samples had detectable levels ofaluminum, barium, chromium, copper, iron, mercury, nickel, selenium, and zinc. Cadmiumand lead were also detected in most species.

The extent of the wetlands in the vicinity of the North Disposal site is generally as presentedin Figure 3, which was transposed from NWI maps. The plant community reported by theNWI in the immediate vicinity of the North Disposal site was found to be the same as thatobserved in this area by WCC biologists (common reed).

3.6 SUPPLEMENTAL PHASE III WETLANDS INVESTIGATION

In response to EPA's March 29, 1990 review comments of the Technical Data SummaryReport (TDSR) (USEPA, 1990a), Du Pont proposed a Supplemental Phase III effort to aidin the assessment of potential ecological impacts associated with the Site and to supplementand clarify data collected in Phases II and III. This proposed work responded to all ofEPA's comments of March 1990 and was submitted as part of a Draft Work Plan on April12, 1990 (WCC, 1990b).

On May 8, 1990 Du Pont received comments from EPA on the Draft Work Plan. Thesecomments were responded to in a letter submitted to EPA on July 5, 1990. On August 9,1990, EPA responded to the letter and included requests for additional data collection. ADraft Scope of Work was submitted to EPA on September 26,1990, which incorporated andaddressed all EPA comments (WCC, 1990c). This Scope of Work included fieldinvestigations and laboratory analyses for: surface water chemistry including sources oforganic carbon; sediment chemistry and physical parameter analyses; sediment toxicitytesting; benthic community surveys; and vegetation bioaccumulation. Additionally, onOctober 31, 1990, WCC submitted a proposed Scope of Work for field collection andanalyses of fish tissue from the Christina River. This Scope of Work was accepted byDNREC and EPA on November 12, 1990. The Supplemental Phase III sampling plansummary is presented in Table 11.

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Field investigations for the Supplemental Phase III Wetlands Investigation were conductedduring the week of October 8, 1990, and the fish tissue sampling was conducted during theweek of November 12,1990. Results were presented in a Supplemental Phase III WetlandsInvestigation Report submitted to EPA on May 20, 1991 (WCC, 1991).

3.6.1 Objectives

The overall objective of the Supplemental Phase III Wetlands Investigation was to evaluatethe relative toxicity to aquatic biota of Christina River sediments and wetlands sedimentsin the Site vicinity compared to toxicity in reference station sediments.

Surface water samples were collected from the North Disposal site wetlands to obtainadditional water quality data for comparison with state and federal criteria for theprotection of freshwater aquatic life and to demonstrate the potential for transport ofsuspended sediment from the area. The objective of the sediment chemistry program w§to define the chemistry of sediments used in the solid phase toxicity tests and to devjadditional data regarding the distribution of metals in subsurface sediments (6 to 18 inches)collected in the Christina River and at the North and South Disposal sites.

The objective of the solid phase sediment toxicity testing was: to assess the relative toxicityof Christina River sediments, and wetlands sediments associated with the North and SouthDisposal sites to aquatic biota; and to use the toxicity testing data in conjunction withsediment chemistry and benthic community data in the Sediment Quality Triad to assesssediment quality. The objective of the benthic macroinvertebrate survey was to bettercharacterize and assess benthic communities in the.study area and for input into theSediment Quality Triad. Fish were collected from the Christina River to provide edibletissue samples to DNREC and EPA, and to provide additional information on possibletissue contamination for input into the human health evaluation. Plant tissues werecollected and analyzed for TAL metals to address EPA concerns that some of the wetlandsvegetation at the South Disposal site may bioaccumulate and release metals to the ChristinaRiver through the annual cycle of detrital decay.


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3.6.2 Scope

The scope of the Supplemental Phase III study involved the collection and analyses ofsediments, plant tissue, fish tissue, and surface water for TAL metals, assessing the relativetoxicity of the sediments to aquatic biota, and further characterization of benthiccommunities. Surface water samples from the South Disposal site were collected per EPA'srequest as an input to the MINTEQA2 model to be run by the EPA.

3.6.3 Results

Results of the Supplemental Phase III field effort and laboratory analyses are summarizedhere. Data are discussed in more detail by media in Section 4.0, Chemical ConstituentCharacterization.

Analyses of surface water samples from the North Disposal site showed that aluminum,cadmium, chromium, copper, iron, lead and zinc exceeded chronic and/or acute waterquality criteria in some surface water samples.

Chemistry analyses of surficial Christina River sediments found that all sediments includingthose from the reference station, contained levels above the TVGs for chromium, iron,manganese and nickeI. u1ft6Btf TedTnierif collected* at RSIt and RS12 (north bank of river)also contained feV<e& of arsenic, cadmium, lead and zinc above the TVGs. Subsurfacesediments from the Christina River had levels of chromium, iron, manganese and nickelabove the TVGs.

Most surficial wetlands sediments collected in the North Disposal site drainageway exceededthe TVGs for chromium, copper, iron, lead, manganese, mercury, nickel and zinc.Subsurface sediments from several North Disposal site stations showed a trend of increasingmetals concentration with depth. The TVGs were exceeded for most metals (for whichvalues exist) at stations AS07, AS08 and AS09.

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Surficial sediment collected from all three South Disposal site stations exceeded all TVGswith the exception of arsenic and mercury. All subsurface sediments at all South Disposalsite stations exceeded TVGs for chromium, iron, lead, manganese, and nickel.

I- Solid phase toxicity testing of sediments collected in the Christina River showed that survival.- of the midge larvae exposed to sediments from RS01, RS07, and RS12 was significantly lessthan survival in reference station sediments. Growth rates of midge larvae were significantlylower in sediment from Station RS12 when compared to reference station growth rates.Sediments from North Disposal site stations AS07, AS08 and AS09 resulted in significantlylower survival of midge larvae when compared to survival in reference station sediment.

81 Growth rates of midge larvae exposed to sediments from stations AS07, AS08 and RS13were significantly lower than the growth of organisms exposed to sediments from RS15.

No significant differences were found when survival data from the South Disposal site werecompared to the field reference station, but growth of midge larvae exposed to sedimentsfrom AS03 was significantly less than that of those exposed to field reference sedimes

In addition to toxicity testing using midge larvae, solid phase toxicity testing using anamphipod was also performed. Since the results of the negative control did not meet theacceptability criteria defined in Nelson et al, (1989), EPA recommended that these data notbe used in the EE for the Site.

A total of 31 different benthic taxa were collected in the Christina River, with the most taxa(18) collected at the field reference station and the least taxa (5) taken at RS12. Thedominant invertebrate group at all river stations was the Oligochaeta. Twenty-eightdifferent taxa were collected from the North Disposal site wetlands. Total taxa per stationranged from four at Station AS09 to 11 at Station AS 12. Tubificid worms dominated thesamples at all stations except Station AS09. .

A total of nine samples of five different species of fish were analyzed for fillet TAL metalslevels for use in the Human Health Evaluation (Volume I of the Risk Assessment). Silver,chromium, and mercury were the only non-essential elements detected in fillet tissues. It

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is important to note that lead was not found above the detection limit in any of the fish filletsamples.

Vegetation tissue analyses on spatterdock (Nuphar sp.) collected from the South Disposalsite suggest that levels of certain metals are higher in these plant tissues than those collectedat the field reference station. At all locations, concentrations of almost all metals werehighest in the root, followed by the rhizome, with leaf tissues containing the lowestconcentration.

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4.0CHEMICAL CONSTITUENTS CHARACTERIZATION

The chemical constituents characterization was conducted to describe and assess theprevalence of Site-related constituents in environmental media (e.g., soils, surface waters,sediment and selected biota). The results of this constituent characterization were used forinput into the identification of ecological constituents of concern presented in Section 5.0.For the purposes of this report, all references made to constituents of concern implyecological constituents.

4.1 DISPOSAL HISTORY

Available information concerning quantities and characteristics of wastes disposed at theDu Font-Newport Site have been summarized in Section 1.2.1 of the RI/FS Work Plan(WCC, 1988b). The North Disposal site received a variety of waste materials during itsoperation from 1902 to 1974 including Lithopone, copper phthalocyanine, Quinacridone,"Afflair" pigments, metal production, chromium dioxide and miscellaneous low volumeprocess wastes and garbage. The composition of these wastes is described in the above-referenced document. The constituents associated with wastes disposed at the NorthDisposal site include the Site target parameters barium, zinc, and cadmium from Lithoponewastes, as well as copper from copper phthalocyanine wastes, nickel from thoriated nickeland chromium from chromium dioxide wastes. Waste materials from the Lithopone pigmentprocess were also disposed at the South Disposal site.

42 SURFICIAL SOILS

Soil samples from the North Disposal site were collected and analyzed for Site-relatedconstituents (Figure 5). Samples SGS-3 and SGS-4 were collected about 0.2 miles west- ^ "7northwest of the North Disposal site in an area without any historical or present dayoperations or disposal. These samples represent the majority of the cap material at boththe North and South Disposal sites.

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As requested by the EPA (EE Scoping Meeting, March 5, 1992), these soil sample datawere compared to local and regional average values from the United States GeologicalSurvey (USGS) (Shacklette and Boerngen, 1984). The regional average and range forselected soil constituents represent data from the Eastern United States. The local valuesare based on the data from the USGS sampling station nearest to the Du Font-Newport Sitewhich is located in Delaware approximately 30 miles south of the Site. The local valuesshould be considered as representative estimates since they are interpolated from afrequency distribution and are not the absolute values measured at the sampling station.

The North Disposal site surface soil metal concentrations from (SGS-3jand[SGS-4 Wereconsistent among themselves and all of their mean values agreed wilhme mean-values forthe Eastern United States and with the local Delaware station estimates (Table 12).

Sample SGS-6 was collected at a vegetationless area of the North Disposal site in thesurficial soil (0 to 6" deep). This sample is not representative of the Disposal Site capmaterial and likely contains Site-related constituents. It is estimated that this S£represents no more than 10 percent of the North Disposal site area. Soil from the No!Disposal site Station SGS-6 values showed high soil levels of some constituents. Theconcentrations of barium, cadmium, and zinc exceed either the Eastern United States meanvalue, or the local Delaware station estimates by about one to two orders of magnitude(Table 12). Cadmium falls within the typical range presented in Dragun (1988) for nativesoil concentrations of various elements. Copper, lead and mercury concentrations fall withinthe range given in Table 12. Barium and zinc concentrations showed the greatest departurefrom the USGS reference values. Nickel levels at Station SGS-6 exceeded the referencestation mean and the USGS reference value by about a factor of three to five times.Surficial soil concentrations of chromium and arsenic at SGS-6 were equal to or lower thanthe levels in the Eastern United States and the local Delaware soil samples. Surficial soilconcentrations of aluminum, iron and manganese in this sample showed little difference incomparison with the Eastern United States and local Delaware values.

At the South Disposal site there were no adequate surficial soil sample data. Althoughsome test pit samples were collected at the South Disposal site, these samples were collected

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at a depth of about four feet/and contained the Lithopone material.jt These saiipnot representative of the cap material that terrestrial organisms would be exposed to amwere therefore, not utilized in the EE to characterize soils at the South Disposal site. Sincesimilar cap rnj ri was tilized at both the North and South Disposal site, the data fromStations SG^3ahd SGS-4jwere utilized to characterize the cap material at the Sout£._Disposal site.

Barium, cadmium, copper, lead, mercury, nickel, and zinc are the constituents of interestbased on soils data from the Du Font-Newport Environmental Evaluation. These metalswill be further scrutinized in subsequent sections to document their importance asconstituents of concern.

43 SEDIMENT

A preliminary sediment survey was conducted during the Phase I investigation to documentthe presence of any Site-related constituents hi the Christina River. Sediment cores werecollected at six locations near the Site and sectioned into discrete depth intervals to evaluatethe geographic and depth distributions of Site-related constituents. The sampling locationsand analytical results of this survey were presented in Volume 3, Appendix J of theDu Font-Newport Site Work Plan (WCC, 1988b).

This survey confirmed the presence of high sediment concentrations of barium, cadmium,lead, and zinc in the river sediment, near the Site. The data showed that the highestconcentrations for some metals were found in the deeper sediments and may be associatedwith higher levels of metal input during the historic operation of the disposal sites. This wasmost evident in the cores taken from stations located between the North and South Dispos;sites and downstream near the James Street Bridge. The lack of a consistent pattern ofsignificantly higher concentrations of metals in the surficial sediment may also suggest thatcurrent sediment loading rates from the disposal sites drainageways, and deposition ofmetals precipitating out from the groundwater may be lower than inputs from historicoperations at the disposal sites. The results also showed that metal levels were highly

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variable geographically. This identified the need for more sediment data and in subsequentstudies the sediment surveys were expanded.

43.1 Normalization Approach

Extensive data on surficial sediment chemistry have been collected throughout the studyarea since the Phase I preliminary survey. These data have been summarized in Section 3.0.The sediment metals levels in all subsequent studies have also been found to vary withlocation of collection, and physical and chemical characteristics of the sediment. In orderto clarify variability in sediment metals levels due to physical and/or chemical sedimentcharacteristics, the EPA requested that the sediment data be normalized and the constituentcharacterization based on normalized sediment chemical values. The results of this processare presented below. The data will be compared to the TVGs and other appropriateguidelines as presented in Table 7 and described in Section 3.2.2.

The physical characteristics of the sediments collected in the Du Font-Newport study &••such as weight percent of clay and silt and the weight percent of organic matter showerconsiderable variations among the approximately 60 surficial sediment samples collectedduring the wetlands investigations. For example, the proportion of silt plus clay sizeparticles (i.e., irm :• > in the sediment samples averaged 75 percent by weight, but the rangewas from 8.2 to y?.4 percent (Appendix Tables A-3, B-l, C-5). Sediment physicalcharacteristics have a profound effect on the trace metal levels in sediments; this isespecially true since trace metals have a strong affinity for co-deposition with the fine-grained silts and clays and organic matter. Consequently, broad variations in metalconcentrations among the stations are to be expected and have been observed. Thesediment data show that metal concentrations among the stations can vary by as much asthree orders of magnitude. This high level of natural variation in metal deposition rate,coupled with the fact that metals from natural and anthropogenic sources accumulatetogether, makes it difficult at best, to distinguish areas with high anthropogenic metalloading without first compensating for the effects of grain-size on metal deposition.

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A standard practice among sediment geochemists faced with this dilemma is to firstcompensate for the effects of grain size on metal deposition, and second to identify samplinglocations with anthropogenic metal inputs by calculation of a Site-specific enrichment factor(Windom, et al, 1989). This compensation process is termed normalization and is definedby Loring (1991) as "the attempt to compensate for the natural variability of trace metalsin sediments so that any anthropogenic metal contributions may be detected and quantified."

Normalization can be accomplished mathematically by either a granulometric approach ora geochemical approach. The granulometric approach involves dividing the sediment metalconcentration values by either the organic content or the weight percent of the specificgrain-size fraction (usually the weight percent of sediment <63 /urn) that show the best linearcorrelation with a set of specific metal values (usually aluminum). Alternatively, thegeochemical approach involves dividing the sediment metal concentration by theconcentration of an elemental "proxy" that most closely represents the local mineralogicalconditions and the grain-size variations in the sediment. The elements aluminum, iron,scandium, cesium and lithium have all been used for geochemical normalization of metaldata for evaluations of contaminant distributions. While the geochemical approach tonormalization may be preferred, no acceptable proxy element was available in the data setfor the Du Font-Newport Site. The elements scandium, cesium, and lithium were notmeasured and some levels of iron and aluminum exceeded the expected concentration insediment of this area, suggesting some potential anthropogenic loading of iron andaluminum. For this reason the granulometric approach was selected to normalize thesediment data collected in the study area.

To select between the grain-size (weight percent) and organic content (weight percent)options for the granulometric normalization a correlation/regression analysis was conductedby comparing each of these variables with their respective concentration of aluminum.Aluminum was selected since it is the most abundant element in the sediments and is theelement most closely related to the local mineralogy, due to the fine-grained secondaryaluminosilicate clay minerals that contain the deposited trace metal. Although a few higheraluminum values are present in the data set, they will equally effect both of the


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correlation/regression analyses and therefore not hamper selection of the most highlycorrelated normalization variable.

The correlation/regression analysis showed that weight percent of mud (sediment <63in the sediment samples was significantly correlated with the aluminum concentration (r =0.5, p £ .001) while weight percent of organic matter was not correlated (r = .15) withaluminum concentration (Figure 6). The sediment metal concentrations were thereforenormalized to weight percent of mud. The results are presented in Table 13.

The normalization process yielded a set of metal values that could then be used toeffectively compare sediment rnetal levels from one location to another. Geochemists havefound that the most useful way of effecting this comparison is to calculate a ratio of thenormalized metal level at one location to the normalized metal level at an appropriatereference location; preferably one location in an area unaffected by Site-relatedanthropogenic inputs. This quotient is termed an enrichment factor (EF). Values of theEF ranging from 0 to 1 are representative of locations where the sediment loading fiparticular metal are equal to or less than that at the reference station. Values greater tone may be indicative of anthropogenic sediment loading in excess of that at the referencestation. The probability of contaminant loading increases with the increasing positive valueof the EF.

In this study an upstream reference Station (RS15) was sampled and the normalized metaldata from this station were used to calculate the metal specific EFs for all other river andwetland sampling stations.

432 Results

A total of approximately 60 sediment samples were collected throughout the study areaduring all phases of investigation. Surficial sediment (0-6" depth) was collected mostfrequently (42 samples) with occasional sampling at 6" to 12" (14 samples) and 12" to 18"(4 samples). Moreover, the surficial sediment bears the closest relationship to both theoverlying water chemistry and the benthic biota. Therefore the following discussion of

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sediment chemistry will focus on the surficial sediment data. However, if a maximumconcentration for any metal was measured in one of the deeper sediment samples itspresence is noted in the discussion.

For the purpose of discussion, the results of the sediment chemistry characterization will bepresented in the following sections: North Disposal site drainageways; South Disposal sitepond and wetlands; and Christina River. The sediment metal concentrations andenrichment factors will be discussed and the data compared to appropriate reference valuessuch as the TVGs and other appropriate guidelines (Table 7).

4.3.2.1 North Disposal Site Drainageways

There are two North Disposal site drainageways, the main drainageway and a sub-basindrainageway containing Stations AS 10 and ASH, located southwest of the North Disposalsite. In the North Disposal site drainageways sediment metal levels tended to be lowest atupstream Station AS 12 in the main drainageway and at Stations AS10 and ASH in the sub-basin drainageway. Higher metal levels were detected in the central portion of the NorthDisposal site drainageway (Stations AS06, AS07, AS08, AS09) (Table 13). Of theindigenous metals that are not naturally abundant, arsenic, cadmium, chromium, copper,lead, mercury, nickel and zinc occurred at concentrations exceeding the TVGs among allstations at least once during the three phases of sediment sampling (Figure 7). Barium,iron, and manganese exceeded the Great Lakes Harbor Sediment Guidelines (ACOE, 1976)and are, therefore, included in the discussion. Each of the metals will be discussed in turnbelow.

A total of 15 stations were sampled throughout the study area during Phase II. Of these,eight were re-sampled in Phase III and three were re-sampled in Supplemental Phase III.On average, the arsenic concentrations at re-sampled stations were about 50 times lowerthan the arsenic levels measured in the Phase II sampling. An in-situ geochemical changeof this magnitude is untenable and either analytical or mathematical errors occurred duringarsenic measurements for Phase II, suggesting these data are invalid. Although the

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suggested QA problems for arsenic were not noted in the QA audit, these data were notused and the more recent arsenic data were relied on for evaluation in the EE.

Arsenic levels at all North Disposal site drainageway stations sampled during the September1988 (Phase II) study were high. The maximum value of 435 ppm measured at Station AS09exceeded the 33 ppm TVG for arsenic. However, data collected during Phase HI andSupplemental III did not confirm these high arsenic levels, except at Station AS07. Asimilar trend of unconfirmed high arsenic levels in Phase II sampling at the South Disposalsite wetlands and Christina River stations was also observed.

Among those data considered acceptable, the high arsenic levels appear to be confined tothe central portion of the drainageway at Station AS07. The maximum sediment value ofJ.17 ppm arsenic in Phase III Sjim/pMng and the corresponding high enrichment factor (EF)of 11.0 suggest the presence c-lminor nthropogenic arsenic loading in the central portionof the North Disposal site drainageway. No other areas of potential arsenic loading wereidentified in the drainageway.

TheJjarium levels in all North Disposal site drainageway samples are high. The maximumbarium concentration of 4510 ppm measured at Station AS07 exceeds the Great LakesHarbor Sediment Guideline of <20 ppm. Although barium is present at all North Disposalsite drainageway stations, the EF values show it is most abundant at Station AS07 in thecentral portion of the drainageway where EF values of 28 to 39 suggest anthropogenicbarium loading.

The cadmium concentrations at Stations AS07 and AS09 in the central portion of the NorthDisposal site drainageway exceeded the TVG for cadmium of 31 ppm. A surficial sedimentmaximum of 66 ppm occurred at Station AS07 during Phase III sampling while 255 ppm wasmeasured in sediment from 6" to 12" deep at Station AS09 in Phase HI. High cadmium EFvalues correspond with these data and suggest anthropogenic cadmium loading occurs in thecentral portion of the drainageway.

EE Rpt/Sect 4-5/88C2076-4V/DPNS 4-8 4-29-92

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The hromiurg_ooncentrations at all study Site stations exceeded the chromium TVG valueof 25 ppm during all phases of the study. A study maximum of 576 ppm was measured atStation AS09 in Phase II. This suggests that the guideline value is set too low for this areaand/or that chromium is an ubiquitous contaminant in the Christina River Basin. In thiscase, the sediment EF value appears as a more useful parameter for the delineation of areassubject to Site-related anthropogenic chromium loading. The EF values were slightlyelevated, ranging from 1.7 to 5.7, at Stations AS07, AS08 and AS09 in the North Disposalsite main drainageway, while the values in the Station AS10/AS11 drainageway andupstream Station AS12 ranged from 0.4 to 1.0, showing no evidence of anthropogenicchromium loading at Stations AS10, ASH, or AS12.

The copper concentrations at all North Disposal site drainageway stations except StationAS 10 exceeded the TVG of 136 ppm. A maximum concentration of 4130 ppm wasmeasured in the 6" to 12" deep sample from Station AS09 hi Phase HI. The maximum EFvalues occurred in samples from the central portion of the North Disposal site drainageway.At Station AS07 the EF values ranged from 55 to 138 and suggest anthropogenic copperloading at this location.

Most of the iron measurements at the sediments of the North Disposal site drainagewayexceeded the 17,000 ppm Great Lakes Harbor Sediment Guideline. The maximumconcentration was 63,400 ppm measured in the central portion of the drainageway at AS09during Phase II. Although these levels appear to indicate anthropogenic iron inputs, the EFfor iron for the North Disposal site drainageways provide no compelling evidence of ironenrichment. Additionally, iron appears to be an abundant indigenous metal at mostlocations throughout the Du Font-Newport study area.

Theleadjconcentrations at all North Disposal site drainageway stations exceed the TVG of132 ppm. A study maximum sediment concentration of 40,500 ppm was detected in the 6"to 12" deep sample from Station AS09 in Phase III. The lead EF values for the NorthDisposal site drainageways are the highest EF values calculated for any nietal in theinvestigation. The EF values at Station AS07 in the central portion of the North Disposal

BE Rpt/Sect 4-5/88C207&4V/DPN5 4-9 4-29-92

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site drainageway ranged from 230 to 869, suggesting strong anthropogenic loading. LeadEF values from the upstream stations also showed some evidence of anthropogenic loading.

Manganese levels at all stations except Station AS 12 exceeded the <300 ppm Great LakesHarbor Sediment Guideline. The maximum level of 2170 ppm occurred at Station AS09.However, the EF values were low, providing little evidence of anthropogenic manganeseloading to sediment at the North Disposal site drainageway stations.

Mercury concentrations in the North Disposal site drainageway sediments in excess of theTVG value of 0.8 ppm were present at Stations AS06, AS07, AS08 and AS09 in the centralportion of the drainageway. A study maximum mercury level of 9.8 ppm was measured inthe 6" to 12" deep sample from Station AS09 in Phase III. Surficial sediment EF valueswere highest at Station AS07 with values ranging from 10 to 32. These results suggestanthropogenic loading of mercury in this portion of the North Disposal site drainageway.

The nickel concentrations at almost all study Site stations (North and South Disposalwetlands and Christina River) exceeded the nickel TVG of 20 ppm during all phases ofstudy. A study maximum of 61.1 ppm was detected in the 6" to 12" deep sample fromStation AS09 in Phase III. This suggests that the nickel guideline value is set too low forthis area and/or that nickel is an ubiquitous contaminant in the Christina River basin. Inthis case, the EF value appears as a more useful parameter for the delineation of areassubject to Site-related anthropogenic nickel loading. The EF values ranged from 1.1 to 3.2at Stations AS06, AS07, AS08 and AS09 in the central portion of the North Disposal sitedrainageway. These values provide little evidence of Site-related anthropogenic nickelloading in the North Disposal site drainageway.

_The zinc concentrations at almost all study area stations (North and South Disposal sitewetlands and Christina River) exceeded the zinc TVG of 760 ppm. A study maximum of19,300 ppm was detected in the 6" to 12" deep sample from Station AS09 in Phase III. Atthe North Disposal site drainageway high sediment zinc levels were observed in the centralportion of the drainageway at Stations AS07, AS08 and AS09. The EF values at these

EE Rpt/Sect 4-5/88C2076-4V/DPN5 4-10

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stations ranged from 10 to 87 suggesting the presence of Site-related anthropogenic zincloading in this area.

In summary, the central portion of the North Disposal site drainageway shows strongevidence of Site-related anthropogenic inputs of barium, cadmium, copper, lead, mercury,and zinc with less evidence of arsenic, chromium, iron, manganese, and nickel inputs. Theupstream portion of the North Disposal site drainageway at Station AS 12 and the sub-basindrainageway Stations AS 10 and ASH had lower metal levels and EF values. These areashad some evidence of Site-related metal inputs although much less intense than thatobserved for the central portion of the North Disposal site drainageway.

4.3.2.2 South Disposal Site Pond and Drainageways

At the South Disposal site pond and drainageways sediment metal levels of barium, arsenic,cadmium, chromium, copper, iron, lead, manganese, nickel and zinc were found in highconcentrations and exceeded the TVG or other sediment guidelines at least once (Table 13,and Figure 7). The South Disposal site pond Stations AS01 and AS02 had the highest levelsof cadmium. Stations AS03, AS04 and AS05 in the drainageway had the highest/concentrations of arsenic, barium, copper, chromium, lead, nickel and zinc. However,higher concentrations of arsenic and chromium at Station AS03 do not appear to be of;anthropogenic Site-related source. High arsenic levels could not be confirmed in later 1sampling as described in Section 4.3.2.1 and there is no history of chromium disposal at theSouth Disposal site. Moreover, the sediment EF value for arsenic at the South Disposal siteare all near 1.0 and all the chromium values are less than 1.0, providing no compellingevidence of Site-related loadings. Each of the other metals will be discussed in turn belowx

The maximum barium concentration measured in the entire study area was 34,700 ppmmeasured at Station AS03 in Phase III. The EF values range from 58 to 165 providingevidence of Site-related anthropogenic loading in the drainageways. Barium EF values atthe pond stations were 3.6 to 63, also showing evidence of loading.



The cadrnjunuconcentrations at all South Disposal site pond and drainageway stationsexcept Station AS04 exceeded the TVG at least once during the three phases of the study.Pond Station AS01 had the highest level at 77 ppm and a corresponding sediment EF valueof 22. All the EF values for cadmium in the South Disposal site pond and drainagewaysexceed 10, suggesting anthropogenic loading in this portion of the study area.

The copper concentrations at all South Disposal site drainageway stations exceeded theTVG. Station AS03 consistently measured about 1100 ppm and the sediment EF values wasabout 25, suggesting anthropogenic inputs of copper at the South Disposal site pond anddrainageways.

All of the sediment iron levels at the South Disposal site pond and drainageway exceededthe 17,000 ppm Great Lakes Harbor Sediment Guideline. The maximum level was 64,500ppm measured at the drainageway Station AS05 during Phase II. However, the EF valuesall ranged between 0.7 to 1.8, providing little indication of anthropogenic iron loading.

!The lead concentrations at all South Disposal site pond and drainageway stations exceethe TVG. Station AS03 consistently measured about 5000 ppm and the sediment EF valueswas about 75, suggesting anthropogenic inputs of lead at the South Disposal site.

r-'

Manganese levels at all stations except Station AS04 exceeded the <300 ppm Great LakesHarbor Sediment Guideline and the maximum level of 1510 ppm occurred at AS03. TheEF values ranged from 0.6 to 1.8 providing little evidence of Site-related inputs.

A mercury level of 0.91 ppm at Station AS03 exceeded the TVG of 0.8 ppm. The EF valuesfor the South Disposal site pond and drainageways ranged from 0.5 to 1.6, providing someevidence of minor inputs.

The nickel concentrations at all South Disposal site stations exceeded the TVG. Tliemaximum concentration was 43.1 ppm measured at Station AS05. However, as discussedin Section 4.3.2.1, there is little evidence of Site-related anthropogenic nickel loading at


AR3I3I71*


either the North Disposal site or at the South Disposal site. The sediment EF values forthe South Disposal site sediments averaged about 1.

The zinc concentrations at all South Disposal site pond and drainageway stations exceededthe TVG. Station AS03 had the highest concentration among all South Disposal sitestations at 12,800 ppm. The EF values for zinc at these stations ranged from about 4 to 38,suggesting anthropogenic inputs of zinc at the South Disposal site pond and drainageway.

In summary, there is some evidence of Site-related inputs of barium, cadmium, copper, leadand zinc in the South Disposal site pond and drainageway. Of these elements only bariumappears at higher concentration and at higher EF values than those observed for the NorthDisposal site drainageways.

432.3 Christina River

Arsenic, barium, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, andzinc were found to be enriched at one or more stations in the North and South Disposal sitedrainageways. Flow of water from these drainageways to the Christina River may potentiallytransport these metals into the river sediments. Therefore the concentration anddistribution of these elements were evaluated in the Christina River sediment samples. Thedata are compared to the TVG and other guidelines. The EF values were calculated forall sampling stations downstream from Station RS15, which served as the upstream referencestation (Table 13 and Figure 8).

As with sediment data from the North and South Disposal site drainageways, the higharsenic levels measured in the river samples in the Phase II study were not confirmed byrepeat sampling at the same stations in later phases of study. However, arsenic levelsexceeding the TVG value (33 ppm) were measured at Station RS06 and at Stations RS11and RS12 located along the north bank of the river near the CIBA-GEIGY Newport Plant.The maximum level of 131 ppm was measured at Station RS11 during Supplemental PhaseIII sampling in 1990. The EF values at these three locations ranged from about 3 to 9,suggesting a minor level of anthropogenic arsenic loading. The presence of a TVG

——~-

EE Rpt/Sect 4-5/88C2076-4V/DPN5 4-13 4-29-92


exceedance for arsenic in the 6" to 12" deep sample from the upstream Reference StationRS15 during the Supplemental Phase HI sampling suggests arsenic may be ubiquitouscontaminant in the Christina River.

TheJJarjurrt concentrations at all river stations during all phases of study exceeded the Great•"" S ," —.' - ^ __

Lakes Harbor Sediment Guidelines of <20 ppm. The maximum river level of 12,000 ppmoccurred at Station RS11 during Supplemental Phase HI. The EF values provide someclarification of the potential distribution of Site-related anthropogenic barium loading in theriver. The EF values at all near Site stations exceed 1 at least once during the severalphases of study, and a river maximum EF value of 68 was calculated from the Station RS11data. These observations suggest Site-related inputs of barium to the near-Site riversediment.

^Cadmium levels in excess of the 31 ppm TVG occurred at Stations RS11 and RS12. A studywide maximum cadmium concentration of 1020 ppm was measured at Station RS12. Thesestations had correspondingly high EF values suggesting anthropogenic loading.

levels at all river stations exceeded the TVG value of 25 ppm at least once.A maximum value of 488 ppm occurred at Station RS11 in the Supplemental Phase HIstudy. However, the EF values do not show strong evidence of Site-related chromium inputsto the river. The highest EF values were calculated for Stations RS11 and RS1 at 4.4 and3.2, respectively.

levels to exceed the TVG of 136 ppm were at Station RS12 (147 ppm) andat the 6" to 12" depth from Station RS11 (204 ppm) sampled in the Supplemental Phase IIIstudy. These levels correspond to an EF value of about 3, suggesting relatively minorcopper inputs to the river sediment.

ijAi jLyyyjgn measurements in the Christina River sediments exceeded the 17,000 ppmGreat Lakes Harbor Sediment Guidelines. The maximum sediment level of 48,700 ppm wasmeasured at RS07 during Supplemental Phase II. However, the EF values for the river

EE Rpt/Sect 4-5/88C2076-4V/DPNS 4-14 4-2 92

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ranged from 0.7 to 3.5 and provide little indication of a trend of Site-related iron input tothe river.

Lead concentrations exceeding the TVG value of 132 ppm occurred at stations upstream_jj -—' ^and downstream from the near-Site area. The highest level occurred at Station RS11 (2170ppm) and Station RS12 (1440 ppm) along the north bank of the river. These concentrationscorrespond to EF values of about 20 to 40, suggesting anthropogenic lead loading in thisarea.

Manganese sediment concentrations at all stations exceeded the TVG. The maximum levelwas 3830 ppm at Station RS07 in Supplemental Phase HI. The EF values were low, rangingfrom 0.5 to 4.5.

The mercury concentrations in the river were low. The maximum level of 1.3 ppm detectedat Stations RS11 in Supplemental Phase III exceed the TVG of 0.8 ppm. The value wasalso exceeded at Station RS06 and at the reference Station RS15 in the 6" to 12" deepsample. The EF values range from 0.3 to 2.9 showing little evidence of mercury loading inthe river.

The nickel sediment levels at all river stations were low, but did exceed the TVG of 20 ppmat least once during the phases of study. The maximum value was 48.5 ppm measured atStation RS12 during Supplemental Phase III. The EF values for nickel were also low andprovided little evidence of anthropogenic nickel loading in the river.

trations eamedmg the TVG of 760 ppm occurred both upstream anddownstream of the near-Site area. The highest levels occurred at Station RS11 (10,500ppm) and Station RS12 (12,500 ppm) along the north bank of the river. Theseconcentrations correspond to EF values of about 37, suggesting anthropogenic zinc loadingin this area. Minor indications of loading were also observed upstream from the Site,suggesting the potential for some ubiquitous zinc contamination in the river.

EE Rpt/Scct 4-5/88C207WV/DPNS 4-15 4-29-92


In summary, there does appear to be some Site-related anthropogenic loading of some tracemetals in the near-Site portion of the Christina River. Consistently high concentrations ofmetals at Stations RS11 and RS12 suggest metal input near these locations.

To further illustrate the geographic distribution of sediment constituents in the ChristinaRiver the EPA has requested that a graph showing constituent levels versus station locations(on an accurate distance scale) be presented in the EE. In response to this request, threesets of trial graphs were prepared that plotted absolute sediment concentration values, themaximum value, and the mean (where repeat sampling was done) versus the station locationin miles downstream from Reference Station RS15. These plots provided no resolution ofgeographic and or Site-related differences in sediment concentrations since the inherentvariability in sediment metal levels due to differences in sediment physical characteristics,sediment mineralogy, and differential deposition acts to mask anthropogenic loading.

A second set of test graphs of normalized sediment data were plotted versus the stationlocations in miles downstream from Station RS15. These plots required numerouschanges on the sediment concentration axis to accommodate the broad rangeconcentrations between elements such as mercury in the 1.0 ppb range and aluminum andiron in the 10,000 to 50,000 ppb range. Moreover, these graphs do not illustrate thepresence of anthropogenic enrichment among the stations nor do they allow comparison ofthe magnitude of enrichment between the constituents of interest.

A third set of graphs were prepared that compare the sediment enrichment factor versus thestation locations in miles downstream from the Reference Station RS15. These graphs donot have the same inadequacies and effectively illustrate the geographic distribution of thenatural and anthropogenic loading of Site-related constituents in the Christina River.Furthermore, the trends for each metal can be compared directly, allowing a ranking of theconstituents based on their magnitude of enrichment. These graphs are presented inFigure 9 and will be discussed below.

The elements barium, cadmium, chromium, copper, lead, mercury and zinc showed aconsistent pattern of anthropogenic enrichment in the Christina River surficial sediments

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78


collected near the Site (Figure 9). The elements aluminum, arsenic, iron, manganese, andnickel showed no similar trends of near-Site enrichment and will not be discussed further.

From the Reference Station RS15 downstream to and including the area around the mouthof the North Disposal site drainageway there does not appear to be any consistent patternof metal enrichment. However, from this point downstream there are two areas where thereis a consistent pattern of metal enrichment among all seven constituents. The first area isfocused at Stations RS12 and RS11 located along the north river bank near the DisposalSite area. These two sampling stations were located very close to the shoreline along thenorth river bank and adjacent to numerous Disposal Site seepage points and may not berepresentative of the full river cross-section of sediment in this area. It is likely that metalscarried into the river by the seepages are co-precipitated out of solution by chemicalcomplexation with the abundant iron hydroxide precipitates that form by oxidation when theiron in seepage water is exposed to air. This mechanism may account for the higher metallevels in sediment collected in the immediate vicinity of the seepage discharge mixing zones.

However, it is unlikely these metal-enriched nearshore sediments cover a broad area in thissection of the river since the seeps are small and their contribution to total groundwaterloading is small. The groundwater will be discussed below in Section 4.5 and thegroundwater loading estimates will be presented in the Feasibility Study (WCC, in prep.).

Immediately downstream from this area at Stations RS07 and RS10 there is an abruptdecline in metal enrichment that suggests that downstream transport from the Disposal Sitemay be limited. The enrichment factors for all metals declined to a minimum value atStation RS10 located about 0.7 miles below the James Street Bridge. The absolute sedimentmetal concentration, the normalized sediment values and the enrichment factors at thisstation were all equal to or less than the values reported for the upstream Reference StationRS15. There do not appear to be any particularly anomalous features about the sedimentphysical features such as grain size and organic content at RS10 that may explain thisminimum values other than limited downstream transport.

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All the sediment metal levels abruptly increased again at Stations RS05 and RS06 locatedabout 0.4 miles downstream from Station RS07. The enrichment factor values for barium,cadmium and zinc at Station RS05 exceeded those at the Reference Station (RS15) by atleast one order of magnitude while those for copper and lead were at least five timesgreater. TOMS abrupt increase in metal enrichment in the Station RS05 and RS06 areasuggests that another source of constituents may have contributed to the metal loading hithis areO The source may have been drainage from the South Disposal site during historic

_^ __operations. The lithopone waste was transported to the South Disposal site in a pipelineand discharged as a slurry. The transport water apparently drained off-site through an eastflowing ditch and discharged to the Christina River at the RS05 and RS06 Station locations.Aerial photographs taken during operation of the South Disposal site appear to confirm thishistoric drainage pattern.

Further downstream at Station RS08 the sediment concentrations of cadmium, chromium,copper, lead and mercury declined to nearly the same values observed upstream at thereference station and showed no evidence of anthropogenic loading. The element bzand zinc showed some minor enrichments with values of 4.8 and 3.3, respectively.the maximum sediment zinc level at RS08 did not exceed the TVG. Likewise the bariumlevels in sediments at RS08 was 583 ppm or 20 times lower than the observed at RS11 alongthe north river bank. Since barium sulfate is poorly soluble and exhibits low toxicity, it isunlikely the sediment barium levels at RS08 present any risk to aquatic biota.

4.4 SURFACE WATER

A variety of freshwater systems are present in the study area and each can have a differentwater chemistry. In the vicinity of the North Disposal site there are tidal and non-tidalwetland drair aeways, where flow rate depends on both season and tidal stage. In thevicinity of th>- outh Disposal site there are .non-tidal wetland drainageways and a pond.The Christina ver, which bisects the Site, is a freshwater tidal river with a daily tidal rangeof about 4 to 5 feet at the Site. As described in Section 3.0, water samples have beencollected from all of these systems during Phase I river studies, and Phase II, Phase III andSupplemental Phase III Wetland Investigations. Selected TAL metal data from the:tiese

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investigations will be presented and discussed in this section to characterize surface waterchemistry in the study area. The discussion of the surface water data will be in the followingsequence: North Disposal site drainageway, South Disposal site pond and drainageway andthe Christina River. The results for total TAL metals analyses will be compared to theWQC or other appropriate references (Table 8). Hardness dependent criteria levels willbe based on Site-specific hardness levels where these data are available.

4.4.1 North Disposal Site Drainageways

In the North Disposal site drainageways water samples were collected at seven differentlocations from upstream Stations AS 12 and AW04, though the central portion of thedrainageway at Stations AW05, AW06 and AS09, and downstream at the mouth of thedrainageway at the Christina River at Stations RS13 and RS14 (Figure 10). In general, thehighest metal levels were measured in water samples from the central and downstreamportions of the North Disposal site drainageway, while those from the upstream stationstended to be lower (Table 14). Among all stations in the North Disposal site drainageway,the total metal levels for aluminum, cadmium, chromium, lead, iron, mercury, and zincexceeded the acute WQC at least once during the various phases of study. The elementbarium has no criteria, but is present at the North Disposal site and the apparently highconcentrations in the water samples require its inclusion. Total surface water concentrationsfor each of these metals will be discussed below.

The total aluminum levels at Stations AS09, RS13 and RS14 ranged from 545 to 1100 ppbin the unfiltered (total) water samples. The maximum value of 1100 ppb measured atStation RS14 exceeds the acute criteria of 750 ppb. However, high total aluminum levelsare expected in the turbid tidal waters of the Site since fine-grained aluminosilicate mineralsare continually re-suspended from the 'Christina River basin sediments. When the riverwater samples were filtered for the dissolved aluminum analyses the aluminumconcentrations were significantly reduced in comparison with the unfiltered total aluminumvalues. For example, the total aluminum level at RS14 was 1100 ppb, but after filtration thedissolved aluminum level was reduced to 82 ppb, indicating that most of the aluminum waspresent in the paniculate form.

EE Rpt/Sect 4-5/88C207fr4V/DPN5 4-19 4-29-92


The barium levels were highest in the central portion of the drainageway with a maximumlevel of 704 ppb measured at Station AS09 during Supplemental Phase III sampling. NoWQC are available for barium, but the average background level in natural freshwaterbodies is 43 ppb, with a range of 2 to 340 ppb (HSDB, 1992).

The cadmium level of 9.9 ppb at Station AS09 was the maximum concentration measuredin the North Disposal site drainageway, exceeding the acute WQC of 3.9 ppb (calculatedwith 100 mg CaCO3/L hardness as directed by EPA). High cadmium levels in surface waterwere measured in the central portion of the drainageway. High levels of cadmium were alsofound in the sediment samples from this area.

The single measure of chromium above the detection limit was 11.5 ppb which occurred atStation AS 12 during Supplemental Phase III. This level exceeds the chronic chromiumWQC of 11 ppb.

The maximum copper level of 54.2 ppb was measured at Station AS09 inPhase III study. It was the only exceedance of the acute WQC of 17.7 ppb (calculated100 mg CaCO3/L hardness) in the North Disposal site drainageway. High levels of copperin both the water and sediment appear to be focused in the central portion of the NorthDisposal drainageway.

The maximum iron level of 3170 ppb was measured at Station AS09 in Supplemental PhaseIII, and this level exceeds the chronic WQC of 1000 ppb.

The lead and zinc levels are high in the central and. downstream portions of the NorthDisposal site drainageway. At Station AS09 a maximum lead level of 286 ppb exceeded theacute WQC of 81.7 ppb and a maximum zinc level of 14,000 ppb exceeded the acute WQCof 117 ppb (both calculated with 100 mg CaCO3/L hardness). High levels of lead and zincin both the water and sediment appear to be focused in the central portion of thedrainageway.

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4 r


Mercury was measured at 0.8 ppb in the filtered (dissolved phase) water sample collectedat AW05 in Phase II. This value exceeds the chronic WQC of 0.012 ppb. Mercury was notdetected in the total water samples from this station, nor in any other water samplescollected from the pond or drainageways of the North or South Disposal sites.

4.4.2 South Disposal Site Pond and Drainageways

Surface water samples were collected at two South Disposal site pond Stations (AW01 andAW02) and at two drainageway Stations (AW03 and AS05). Generally, the highest metallevels were measured in surface water samples from the drainageway stations, while thosefrom the pond station tended to be somewhat lower (Table 15).

Among all stations in the South Disposal site pond and drainageway, the metal levels foraluminum, iron, lead and zinc exceeded the acute WQC, while cadmium, chromium, andcopper exceeded the chronic WQC (Figure 10). Barium concentration hi the water fromthe South Disposal site pond and drainageway were high, averaging about 1000 ppb, andtherefore barium will be included in the following discussion.

The maximum aluminum concentration in the South Disposal site surface waters was 6090ppb, measured at Station AS05 in Supplemental Phase III. This value exceeds the acuteWQC of 750 ppm. However, as discussed previously the high turbidity in the water samplescollected from the study area accounts for the high total aluminum levels measured.

The barium levels in the surface waters at the South Disposal site pond and drainagewaywere high. A surface water maximum barium concentration of 1,570 ppb occurred atStation AS05 in Supplemental Phase III. Barium levels at all South Disposal site pond anddrainageway stations exceed the range of natural barium levels in surface waters of 2 to 340ppb (HSDB, 1992). The highest sediment levels of barium measured in the study area werealso observed in the South Disposal site pond and drainageway.

High concentrations of total cadmium (4.6 ppb), chromium (15.2 ppb), and copper (26.2ppb) occurred at Station AS05 in Supplemental Phase III. These levels exceeded the

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chronic WQC of 1.8 ppb cadmium, 11 ppb chromium, and 19.8 ppb copper (both thecadmium and copper WQC were calculated with a hardness of 183 mg CaCO3/L as directedby EPA). The maximum level of iron was 52,800 ppb measured at Station AS05 inSupplemental Phase III. This level exceeds the 1000 ppb WQC.

The lead and zinc levels are high at most South Disposal site pond and drainagewaystations. The maximum lead value of 126 ppb measured at Station AW03 in Phase IIexceeds the acute WQC of 99.5 ppb (calculated with 117 mg CaCO3/L hardness). Themaximum zinc value of 391 ppb measured at AS05 in Supplemental Phase HI exceeded theacute WQC of 195 ppb (calculated with 183 mg/CaCO3/L hardness). The South Disposalsite maximum for lead and zinc in the sediment also occurred at Station AW03.

A comparison of the South Disposal site and North Disposal site surface water data showsthat samples from the South Disposal site are generally higher in aluminum and bariumwhile North Disposal site samples appear higher in zinc. Their respective levels ofcadmium, chromium, copper and lead appear to be similar.

4.43 Christina River

The surface water chemistry of the Christina River is highly variable and depends on theseasonal discharge conditions and the daily tidal cycle. Although the river is primarily freshwater it does have a minor marine chemical component due to the tidal exchange with theDelaware Bay. Hourly samples were collected in a 12-hour time-series study throughout onecomplete tidal cycle to describe the river water chemistry (Section 3.3.3). This approachprovided data from low tide conditions that may approximate the water chemistry conditionsof the base flow in the Christina River and from flood tide conditions that approximatewater chemistry across a range of dilution conditions. The sampling was conducted duringsummer flow (minimum dilution conditions) on August 13,1987 at 1-hour intervals from lowtide through high tide and back to low tide again. The water samples were collected at theJames Street Bridge. Sampling at this location and time of year may have the greatestpotential for the detection of Site-related constituents, particularly in the river water samplescollected during low tide. Unfiltered water samples were analyzed for TAL metals.

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These unfiltered water quality data were compared to the WQC. The hardness dependentWQC were calculated based on the average water hardness found during the tidal cyclestudy. Hardness was calculated according to Standard Methods 2340B (APHA, 1989) as:

mg Ca CO3/L = 2.4977 [Ca] + 4.118 [Mg]

where, Ca and Mg are the calcium and magnesium concentrations measured in the tidalcycle water samples. The results of this determination showed the hardness averaged 133mg CaCO3/L. Selected data for total metal concentrations are presented in Table 16 andFigure 10 and the results for each metal are discussed in turn below. Based on filteredwater quality data collected in subsequent phases of the wetlands investigation theconcentrations measured in Phase I are largely attributable to particulate-bound metalssuspended in the water column.

The total aluminum concentrations averaged 1495 ppb and ranged from 919 ppb to 2060ppb. AU;VfIucs exceeded the acute WQC of 75Gppb. High turbidity in the Christina Riverwater probably accounts for the majority of the total aluminum. A comparison of these datawith other Site locations showed the aluminum levels were similar to the upstream stationsat the mouth of the North Disposal site drainageway (Station RS14) and were between thelower levels at the wetland drainageway station and the higher values at the groundwaterseepage stations.

The barium concentrations averaged 91 ppb and ranged from 74 ppb to a maximum of 101ppb in a duplicate sample of the RW-7 time-series sample. Neither USEPA or DNRECWQC are available for barium. The average background concentration of barium in surfacewater is 43 ppb with a range of 2 ppb to 340 ppb (HSDB, 1992). In general the bariumlevels in the river tended to be lower than at almost all other locations.

Detectable levels of cadmium were measured once during low tide (4.3 ppb) and againshortly after the beginning of flood tide (9.6 ppb). These values exceeded the hardnessdependent chronic (1.4 ppb) and acute (5.4 ppb) WQC, respectively. The levels were about

EE Rpt/Sect 4-5/88C2076-4V/DPN5 4-23 4-29-92


the same as those measured at the drainageway and wetlands stations, but lower than thosedetected in groundwater seepage.

The maximum chromium concentrations of 12 ppb exceeded the chronic WQC of 11 ppb.No other chromium exceedances were observed during the tidal study. These chromiumlevels were about the same as those measured at the drainageway and wetland stations, butlower than those detected in groundwater seepage.

The maximum copper level measured (12 ppb), did not exceed the hardness dependentchronic WQC of 15.1 ppb. These levels were about the same as the drainageway andwetlands data, but lower than the levels measured in groundwater seepage.

Lead was detected five times among the 12 samples and all detected levels exceeded thechronic WQC of 4.6 ppb. The maximum concentration was 72 ppb. Lead levels weregenerally lower in the river than those measured in either the wetland drainageways or thegroundwater seepage samples.

The maximum zinc concentration of 287 ppb exceeded the acute WQC of 149 ppb and oneother measurement of 141 ppb exceeded the chronic WQC of 135 ppb. No otherexceedances of zinc were observed during the tidal study. Zinc levels in the river weregenerally lower than those measured in the wetlands and the groundwater seepage samples.

The iron concentration throughout the tidal study exceeded the 1,000 ppb WQC. Themaximum iron concentration was 2840 ppb measured during low tide. The ironconcentrations were generally lower in the river water samples than those for either thewetland or groundwater seepage samples.

The elements arsenic and nickel were not detected in the tidal study water samples, andmercury was not measured.

In summary the tidal study data show that aluminum, cadmium, chromium, lead, iron, andzinc levels equal or exceed the WQC. In addition, the element barium shows a stro

EE Rpt/Sect 4-5/88C207&4V/DPN5 4-24

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inverse correlation with tidal stage (i.e., barium maximum correspond with lowest tide),This suggests anthropogenic barium inputs from upstream. < ^ '({\j /ifc

4.5 GROUNDWATER SEEPS /

Groundwater seeps have been identified along the north bank of the Christina River. Someare adjacent to the North Disposal site and others are between the North Disposal site andthe James Street Bridge near the CIBA-GEIGY Plant Area (Figure 11). Groundwaterseepage samples for some of these locations were collected during the April 1991 Phase IIIsampling. Since some of the seeps were dry or had low volume during this sampling,composite samples were prepared for analysis. /

The composite samples were analyzed for dissolved and total TAX metals and some organiccompounds. A subset of these data, consisting of those metals previously identified aspotential anthropogenic constituents in the Christina River sediments were evaluated. Thetotal metal levels for aluminum, arsenic, barium, cadmium, chromium, copper, iron, lead,mercury, nickel and zinc were evaluated. The concentrations of these metals may declinerapidly as the groundwater becomes oxygenated after it seeps out along the riverbank. Themetals will likely co-precipitate out of solution by chemical complexation with the abundantiron hydroxide precipitates that form by oxygenation of the seepage water. However, thesesamples were collected at the point of seepage and this may not allow sufficient time for theco-precipitation of metals to occur. The metal concentrations would be more representativeof poorly oxygenated groundwater than of well oxygenated Christina River water. For thisreason the WQC may not be an appropriate comparative reference for the evaluation ofthese seepage water samples. Nevertheless, at the request of EPA the groundwater seepagedata were compared to the WQC.

The hardness dependent WQC (cadmium, copper, lead, nickel, zinc) were adjusted to themean hardness level among all groundwater seepage samples. Hardness was calculatedaccording to Standard Methods 2340B (APHA, 1989) as presented in Section 4.4.3 above.The average hardness value was calculated to be 166 ppm CaCO3.

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The results of the evaluation for inorganic constituents along with the WQC levels areshown in Table 17 and Figure 10. In general these data show that aluminum, cadmium, leadand zinc exceeded either the chronic and/or the acute WQC at all composite samplelocations. Chromium, copper, and iron exceeded the WQC at most locations, while mercuryexceeded the chronic WQC at only one station. The arsenic and nickel levels do not exceedthe WQC. Barium WQC are not available but a maximum barium level of 21,800 ppb ishigher than the average background concentration in surface water of 43 ppb (HSDB, 1992).The maximum aluminum level of 10,600 ppb in composite sample 4 exceeds the acute WQCof 750 ppb. The maximum cadmium level of 151 ppb in composite sample 1 exceeds theacute WQC of 6.94 ppb. The maximum chromium level of 583 ppb in composite sample4 exceeds the acute WQC of 16 ppb. The maximum copper level of 431 ppb in compositesample 4 exceeds the acute WQC of 28.5 ppb. The maximum iron level of 38,200 ppb incomposite sample 4 exceeds the 1000 ppb WQC. The maximum lead level of 1,220 ppb incomposite sample 4 exceeds the acute WQC of 156 ppb. The maximum mercury level of1.1 ppb in composite sample 4 exceeds the chronic WQC of 0.012 ppb. The maximum zinlevel of 64,700 ppb in composite sample 3 exceeds the acute WQC of 180 ppb.

unc

To estimate the potential for WQC exceedances in the Christina River from this NorthDisposal site and CIBA-GEIGY Plant Area riverbank seepage and any additionalgroundwater loadings, the metal loading estimates to be presented in the FS (WCC, inpreparation) were compared to estimated minimum daily discharge at the Site. Since nogauging station exists at the Site, the discharge estimates were based on discharge statisticsfrom three United States Geological Survey gauging stations located upstream in theChristina River drainage basin (USGS, 1990). This type of evaluation provides highestimates of the concentrations of barium, cadmium,-and zinc that may potentially occurduring low flow conditions. The estimated concentrations will be compared with the WQC.This approach may represent a "worst possible case" scenario.

Since the WQC are presented in metric units, the loading rate estimates in pounds/day wereconverted to jig/day. The rates for barium, cadmium, and zinc were 1.9 x 109 Mg/day,2.26 x 106 Mg/day, and 9.5 x 108 Mg/day; respectively.

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The estimated minimum daily discharge at the Site was based on the sum of estimateddischarges from that proportion of the drainage basin areas of White Clay Creek, Red ClayCreek and the Christina River that are located upstream of the Site and contribute to theriver flow passing the Site. Minimum discharge at the White Clay Creek gauging station was5 ft3/sec, but this station included only 82.5 percent of the basin area upstream from theSite. Therefore the minimum daily discharge at the station was divided by .825 to providean estimate of minimum daily discharge at the Site of 6.0 ftVsec. This process was repeatedfor the proportional drainage area included at the upstream Christina River and Red ClayCreek gauging stations. The discharge contribution from the upstream area of the ChristinaRiver was 0.2 ft3/sec divided by 0.26 or 0.77 ft3/sec and that for the Red Clay Creek was4.5 ft3/sec divided by 0.87 or 5.17 ft3/sec. The estimated minimum daily discharge at theSite is the sum of these three sources and equals 11.94 f /sec or 1.02 x 106 ft3/day. Themetric conversion equals 2.92 x 107 L/day.

By dividing the loading values in /xg/day by the minimum daily discharge in L/day anestimate of the river water concentrations can be calculated. The estimated concentrationsof barium, cadmium and zinc are calculated to be:

iN: EPA and DNREC Watert Quality Chronic Criteria

______....._.__ . _._j (Based on 100 ppm/CaCO3 Hardness )

Barium = 65 ppb - None AvailableCadmium = 0.08 ppb < 1.1 ppbZinc = 32.5 ppb < 110 ppb

The comparison with the WQC show that neither cadmium or zinc exceed the chronic WQClevels. The barium level is about the same as the average barium concentration in mostsurface water (HSDB, 1992) and represents no risk to aquatic biota.

The major assumptions in the calculation are:

• The loading rates are realistic estimates

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• The discharge value is a realistic estimate of the minimum daily discharge atthe Site

• The background levels of the metals in upstream water are low

• The daily tidal flooding at the Site provides no additional dilution

• The loadings are rapidly and completely mixed in the minimum dailydischarge *

This evaluation suggests that although the groundwater and Disposal Site seeps are a sourceof Site-related anthropogenic inputs of metals to the Christina River, their dilution in thelarge volume of river water and the rapid mixing due to daily tidal cycles limits the potentialfor WQC exceedances in the Christina River to small mixing zones immediately adjacentto the areas of groundwater input.

The results of the analyses of the seepage water samples for organic compounds identit r20 compounds that were present in some of the samples. The result of these analyses arepresented in the Human Health Evaluation (WCC, 1992). None of the identifiedcompounds have WQC levels currently promulgated due to insufficient data to developcriteria. Therefore, the concentrations of the organic constituents identified in the seepagewater samples were compared to the Lowest Observed Effects Level (LOEL) as presentedin the EPA Water Quality Criteria Summary (USEPA, 1986). This evaluation identified thepresence of two compounds that either equalled or exceeded the LOEL values: 1,2-dichlorobenzene and tetrachloroethene. The analytical results for these compounds arepresented in Table 17 and each compound will be discussed below.

The 1,2-dichlorobenzene was detected in seepage water composite samples 3,4, 5, 6 and 7.None was detected in samples from seepage points near the North Disposal site. Themaximum value of 1700 ppb occurred in composite sample 3 and it exceeded the LOEL for1,2-dichlorobenzene of 1120 ppb. 1,2-dichlorobenzene is poorly soluble in surface waters,has a high affinity for lipophilic material and some potential for bioaccumulation. However;


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volatilization to the atmosphere is relatively rapid, and it has been shown that 100 ppm 1,2-dichlorobenzene volatilized to less then 1 ppm in unaerated distilled water in three days(Versar, Inc., 1979).

Paniculate sorption and volatilization are likely competing processes in the fate of thiscompound in natural waters. The turbulent conditions in the Christina River caused bydaily tidal flushing may encourage volatilization as one removal mechanism and the highsuspended load may rapidly sorb and sediment an additional amount of the 1,2-dichlorobenzene. Moreover, the maximum 1,2-dichlorobenzene concentration was at leastan order of magnitude lower than the maximum zinc level found in the same seepage watersamples and the zinc loading rate calculations described above predicted little possibility ofzinc WQC exceedances even under low flow conditions in the river. Therefore, it is unlikelythat 1,2-dichlorobenzene would exceed the LOEL in any appreciable area of the ChristinaRiver.

The tetrachloroethene was also detected in seepage water composite samples, 3, 4, 5, 6 and7 with no upstream occurrences near the North Disposal site. The maximum value of 3200ppb also occurred in composite sample 3 and it exceeded the chronic LOEL of 840 ppb, butdid not exceed the acute LOEL value of 5280 ppb. Tetrachloroethene is quite volatile andit has been shown experimentally that 0.5 ppm of the tetrachloroethene that was added, wasvolatilized from a stirred water sample in 26 minutes while 90 percent was lost in only 83minutes (Versar, Inc., 1979). These findings suggest that exceedances of the LOEL fortetrachloroethene in the Christina River are highly unlikely.

In summary, it does not appear that organic constituents in groundwater seepage along thenorth Christina riverbank represent a high level of risk to aquatic biota in the river. Theturbulent mixing as a result of daily tidal flushing and the large volume of river waterpresent in comparison with the small volume of seepage water limits the potential fororganic constituent exceedances of the LOEL values in the river.

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4.6 BIOLOGICAL TISSUES

As described in Section 3.0, fish tissues and wetlands plant tissues were collected from thestudy area during Phase III and Supplemental Phase ffl Wetlands Investigations. These dataare attached in Appendixes B and C, respectively.

In August of 1989,15 species of fish were collected from the Christina River and White ClayCreek portion of the study area. Metals levels detected in whole body tissues from thesespecimens were compared to data available for whole body analyses from the NationalContaminant Biomonitoring Program (Lowe et al, 1985) (NCBP) and the USF & WS(Eisler, 1985, 1986, 1987, and 1988). All fish collected in the River in 1989 had detectablelevels of aluminum, barium, chromium, copper, iron, mercury, nickel, selenium, and zinc.Cadmium was detected in all species except carp (fillets only), and lead was detected in allspecies except black crappie. Of the> metals detected, only cadmium and copper exceededliterature values in two samples each. These samples were collected in the vicinity of theSite, near the field reference station, and in White Clay Creek. The silvery minnow samcollected in the Site vicinity contained the highest levels of aluminum, barium, chroiron, lead, and zinc, as compared to the upstream samples.

Aluminum levels in the silvery minnow collected in the Site vicinity were approximately fivetimes the aluminum level in those collected at the field reference station. vBarium levels inminnow from the Site were 1.6 times that of the field reference minnow, whileC iromium

j/f~\ /*—"• "~*-. ^ •"—9*** —- ,, , „ . —-^was 3.5 times,/iron 4.0 times, lead 6.0 times and(zincl.8 times the level found in the fieldreference stationr'it must be noted that these values were obtained from a single compositesample from each location. The silvery minnow sample from the Site vicinity was acomposite of 14 fish, while the sample from the upstream field reference station, as well asfrom White Clay Creek were composites made up of five fish. Since these data are derivedfrom such a limited database, the natural variance of metals detected in these minnows atany given location is unknown. Therefore, it can not be said whether or not the differencein concentrations between the Site vicinity, White Clay Creek and the upstream referencestation represent natural variability or differences due to Site-related impacts.

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Alternatively, the high levels of metals detected in the silvery minnows may be directlyrelated to their feeding habits. They are known to ingest mud, bottom ooze and algae(Scott and Crossman, 1973). Since these fish were analyzed as whole body samples andwere not eviscerated prior to analyses, the metal results are biased upward by the sedimentscontained in their digestive tracts, in addition to any metals which may have been presentin their tissues. Given the elevated levels of several of these metals in sediments near theSite, and the minnows habit of ingesting mud, the silvery minnow data should be used withcaution.

Reference values for cadmium, copper, lead, and zinc contamination in whole fish areavailable from the NCBP (Lowe, et al, 1985). These data represent the minimum andmaximum concentrations from freshwater fishes collected at 112 monitoring stations acrossthe United States. Reference values for chromium (17 species whole body) and mercury(Northeast United States) are listed in Eisler (1986, 1987).

.>,—., . - " '

Cadmiunj'levels in silvery minnow collected in the Site vicinity (0.08 ppm) fall in the lower-enar"ofthe range listed by Lowe et al (1985) (0.01 - 0.35 ppm).

Conversely/chromiunyin silvery minnow from the Site vicinity (0.7 ppm) is at the high endof the range-given by Eisler (<0.1 - 0.8 ppm). jEopperyin Site vicinity minnows (1.6 ppm)is well below the high value (24.10 ppm) listed in Lowe et al (1985). /Cead in Site vicinityminnows (1.2 ppm) was near the middle of the NCBP range of 0.01 -T$4 ppm.

Mercury was not detected in Site vicinity silvery minnows, and zinc (38.4 ppm) was wellwithin the range of 8.82 - 109.2 ppm given by Lowe et al (1985).

Fish tissue data collected in the Supplemental Phase III Investigation are attached inAppendix C but were not evaluated in this EE.since levels represent concentrations in filletsonly, which are used to assess human health in Volume I of the Risk Assessment.

In addition to fish tissues, vegetation tissues (root, rhizome and leaves of spatterdock) werecollected during the Supplemental Phase III Wetlands Investigation and analyzed for TAL

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metals. These data are attached in Appendix C. Analytical data suggest that arsenic,barium, cadmium, chromium, copper, lead, mercury, and zinc exhibit higher concentrationsin root and rhizome tissues collected at the South Disposal site compared to the sametissues collected at the field reference station. Root tissues were consistently found to havethe highest concentrations of metals compared to other plant tissues. With few exceptions,concentrations of non-essential metals identified in tissues were lower than concentrationsin the sediments in which the plants were growing. Overall, above ground leafconcentrations of non-essential metals were low compared to sediments and other tissues.The potential for impact to receptors as a result of ingestion of spatterdock tissues will beevaluated as part of the exposure assessment.

4.7 SUMMARY

Based on the disposal history, the elements barium, cadmium, chromium, copper, nickel, andzinc are constituents of interest at the Site. The sediment chemical characterizationidentified arsenic, iron, manganese, mercury, and lead as additional constituentsThe surface water and groundwater seepage chemical characterization identifiedas an additional constituent. The fish tissue data confirmed the presence of cadmium andcopper at concentrations exceeding literature values.

' ; 'These results suggest that aluminum, arsenic, barium, cadmium, chromium, copper, iron,lead, manganese, mercury, nickel, and zinc are the constituents of interest at the Du Pont-Newport Site. The concentrations of these metals and their distribution information will be

*

compared to their ecotoxicity and geochemical fate in Section 5.0 to identify the constituentsof concern for the Du Font-Newport Environmental Evaluation.

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5.0CONSTITUENTS OF CONCERN

The chemical constituents characterization in Section 4.0 was based on the disposal historyfor the Site, soils data, sediment and water chemistry, and tissue analysis studies conductedin the Phase I, Phase II, Phase HI and Supplemental Phase III investigations. These studiesprovided data regarding the concentrations and distributions of TAL metals in the ChristinaRiver and the North and South Disposal site wetland and drainageways.

In this section, a three step approach is used to identify constituents of concern for theDu Font-Newport Site. First, the disposal history for each of the two disposal sites wasreviewed to identify what constituents of interest would be expected to occur. Next,chemistry data for soils, sediments, surface water and biological tissues were reviewed toidentify potential constituents of concern. Lastly, Site-specific data on potential constituentsof concern were compared to guidelines and ARARs, lexicological properties andbiogeochemical fate to arrive at a list of constituents of concern for the Du Pont-NewportEE.

5.1 CONSTITUENTS OF INTEREST

For the purpose of this evaluation, constituents of interest are those constituents whichwould be expected to occur at the Site based solely on disposal history. Availableinformation concerning quantities and characteristics of wastes disposed at the Du Pont -Newport Site have been summarized in Section 1.2.1 of the RI/FS Work Plan (WCC,1988b). The North Disposal site received a variety of waste materials during its operationfrom 1902 to 1974 including Lithopone, copper phthalocyanine, Quinacridone, "Afflair"pigments, metal production, chromium dioxide and miscellaneous low volume process wastesand garbage. The composition of these wastes is described in the above-referenceddocument. The constituents associated with wastes disposed at the North Disposal siteinclude barium, zinc, and cadmium from Lithopone wastes, as well as copper from copperphthalocvanine wastes, nickel from thoriated nickel and chromium from chromium dioxide


4R3I3I95


wastes. AiseniCjJead and mercury were metals associated with the sulfide ores used in theLithopone process. Waste materials from the Lithopone pigment process were also disposedat the South Disposal site. The following list of constituents of interest was compiled basedon disposal history at the landfill Sites:

Constituents of Interest North Disposal Site South Disposal Site

Arsenic X XBarium X XCadmium X XChromium XCopper XLead X XMercury X XNickel X XZinc X X

5.2 POTENTIAL CONSTITUENTS OF CONCERN

The list of constituents of interest was further scrutinized using Site-specific soils,surface water and tissue data collected during the wetlands investigations to identifypotential constituents of concern. The concentrations and distribution of the metals inenvironmental samples from the Site-wide sampling programs were compared to variousARARs and other references to identify the initial list of the Site-wide potential constituentsof concern. If a metal exceeded either the sediment TVGs or surface water ARARs(described in Section 3.2) it was included on the list of potential constituents of concern.

The soils data identified lead as a potential constituent of interest. The sediment chemicalcharacterization identified arsenic, iron, manganese, mercury, and lead as other potentialconstituents of concern. The surface water and seepage water chemical characterizationidentified aluminum as another potential constituent of concern. The fish tissue dataconfirmed the presence of cadmium and copper at concentrations exceeding literaturevalues. Cadmium levels were above the literature value in one whole body pumpkinseedsunfish sample (composite of seven fish) collected in the Site vicinity, and in one sample ofsilvery minnow (composite of five fish) sample collected in White Clay Creek. Copperlevels were higher than literature values in one whole body sample of white pe.

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(composite of three fish) collected in the Site vicinity and in one sample (composed of onefish) collected at RS04, approximately 2.5 miles upstream of the Site.

Federal guidelines established for the evaluation of metal levels in sediment that were usedfor the identification of potential constituents of concern included guidelines developed bythe EPA Office of Water Regulations and Standards in the National Perspective onSediment Quality (1985) discussed in Section 3.2. These are not promulgated criteria; theyare only guideline TVG developed to assist in establishing criteria. The TVGs are basedon an organic carbon content of 4 percent. The total organic carbon analyses of sedimentscollected throughout this investigation range from 1 to 5 percent. Iron and manganese,which were not addressed by the EPA, were compared to thresholds for metals in GreatLakes Harbor sediments prepared by the EPA and the U.S. Army Corps of Engineers(1976).

With the exception of chromium and nickel, TVG concentrations were computed by EPAusing the Sediment-Water Equilibrium Partitioning Approach, which uses 1) compoundspecific partition coefficients to predict the distribution of the compound between sedimentand interstitial water and 2) compound-specific WQC and the compound-specific partitioncoefficient to quantify the sediment concentration above which biological effects (i.e., theTVG) may occur.

If the TVG was exceeded in at least one sample, it was placed on the list of the potentialconstituents of concern for the Du Font-Newport EE. As a result of these comparisons,aluminum, arsenic, barium, cadmium, chromium, copper, iron, lead, manganese, mercury,nickel, and zinc are the potential constituents of concern at the Du Font-Newport Site.

5 J CONSTITUENTS OF CONCERN

The concentrations of the potential constituents of concern and their distributioninformation were compared with the following factors to identify the final list of constituentsof concern for the Du Font-Newport EE:

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• Intrinsic toxicological properties

• Presence in, or potential to move into, critical exposure pathways(biogeochemical fate)

Based on the results of the sediment and water chemistry evaluation (Section 4.0) thefollowing constituents of concern were identified for the North and South Disposal sitewetlands and the Christina River:

PotentialConstituents North Disposal South Disposal Christinaof Concern Site Wetlands Site Wetlands River

Barium X X XCadmium X X XChromium XCopper X XLead X X XMercury XZinc X X X

In addition to these elements, aluminum, <enic, iron, manganese and nickel also exceededthe sediment guidelines or the water quant/ criteria in some samples collected from somestations. A thorough examination of the soil data, sediment and water chemistry, andecotoxiciry of each of these metals showed little evidence to warrant their inclusion asconstituents of concern for the Du Pom-Newport EE. The rationale for not including theseelements is presented below.

Aluminum is the third most abundant element in the earth's crust with surface soil levelsin the eastern United States ranging from 0.7 to >10 percent and a mean concentration of3.3 percent. The concentration at a U.S. Geological Survey station located south of theDu Pont Site averaged approximately 3 percent (Shacklette and Boerngen, 1984). Sinceeroded soils are the major contributor to river and wetland sediments at the Du Font-Newport Site, the expected aluminum concentration should reflect soil levels and averageapproximately 3 percent. The mean concentration of aluminum among the 20 surficj


A R 3 I 3 I 9 8


sediment samples from the Christina River was 2.44 percent (standard deviation (Sd) equals0.91). The mean aluminum concentrations among the North and South Disposal sitesediment samples were lower averaging 1.25 percent (Sd = .44) and 2.11 (Sd = .24),respectively. Also, on average, the normalized sediment aluminum concentrations do notexceed the expected level based on local soil levels. These results show that sedimentaluminum levels are below the expected concentrations for the region. Additionally, thesediment enrichment factor calculations based on normalized aluminum levels also show noevidence of anthropogenic loading at or near the disposal sites.

The total aluminum concentrations in the water chemistry samples do show someexceedances of WQC. However, most of this aluminum is present as the suspendedpaniculate minerals that contribute to the high turbidity in the water samples. Filtrationof the water samples confirmed that most of the aluminum was present hi particulate form.Aluminum included in particulate minerals, clays and sand or sorbed to particles areunlikely to be toxic to aquatic biota under the pH regime present in the Christina River andadjacent wetlands (pH range 6.5 to 7.5). Aluminum is poorly soluble at this pH range withdissolved levels ranging from about 0.1 to 1.0 ppb (Drever, 1982).

Arsenic levels in the sediment samples with acceptable analytical results (Phase m andSupplemental Phase HI data) exceeded the TVG value of 33 ppm only at Station AS07 inthe North Disposal site and at three locations in the Christina River among a total ofapproximately 60 sediment samples collected. If the Phase II values of questionable validityand these exceedance values are excluded from the calculations, the average arsenicconcentration among the remaining samples was 9 ppb. This value may represent anapproximate reference value for the Christina River Basin area. The soil arsenic levels inthe area are similar. The observed range of arsenic in soils from the eastern United Statesis <0.1 to 73 ppm with a mean of 4.8 ppm and an estimated arithmetic mean of 7.4 ppm.Local soil samples collected south of the Site averaged 2.6 ppm or lower (Shacklette andBoerngen, 1984). These sediment data along with the low enrichment factor values providelittle evidence of Site-related arsenic contamination in the Christina River and adjacentwetlands sediments.

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The surface water arsenic data also showed no exceedances of the WQC. Neither did theseepage water samples from locations with concentrations of other constituents exceedingthe criteria by orders of magnitude.

Iron is the fourth most abundant element in the earths crust. Surface soil levels in theeastern United States range from 0.1 to >10 percent with a mean of 1.4 percent and anestimated arithmetic mean of 2.5 percent. The soil concentration at the nearest USGSsampling station averaged approximately 1.0 percent (Shacklette and Boerngen, 1984). Thesediment concentrations from the Christina River samples averaged 3.2 percent andconcentrations at North and South Disposal site/stations also averaged 3.2 percent, slightlyhigher than the USGS station value. The sediment enrichment factor values based onnormalized iron levels averaged about 1.0 and showed no evidence of Site-relatedanthropogenic loading.

The WQC for iron is 1000 ppb. This high WQC criterion level is consistent with thegenerally low toxicity of iron to aquatic biota. The total iron concentrations in the w|chemistry samples do show exceedances of! the WQC. However, most of the ironpresent in paniculate form. Filtration of the water~samj)les lowered the average ironconcentration among the North and South Disposal site stations that had both total and

jjes from about 1713 ppb to 345 ppb. This suggests that about 80 percent ofthe iron is present in a particulate form that & not toxic to aquatic biota. Moreover, muchof the remaining iron may be present in the soluble organoinetallic or humic compoundsthat are particularly abundant in wetland and swamp waters. /These forms of iron have littleeffect on aquatic biota according to the WQC for ironjJJ EPA, 1986).

Manganese is an abundant indigenous element that ranges from <2 to 7,000 ppm andaverage about 260 ppm in soils of the eastern United States. At the local USGS soilsampling location the manganese concentration was about 150 ppm. Manganese and ironcommonly co-occur in soils, and in areas with higher iron content higher manganese levelsare to be expected. The Christina River Basin soils do appear to have slightly higher ironlevels as noted above. Sediment levels in the Christina River averaged 895 ppm and theaverage for the North and South Disposal sites was 845 ppm. There did not appear to


AR3I320Q


any evidence of anthropogenic manganese loading in either the wetlands or the downstreamriver sediments based on enrichment factor values.

Although manganese is generally more soluble in surface water than iron, it is not generallytoxic to aquatic biota even at concentrations exceeding 1,000 ppb. Hence USEPA has notpromulgated a WQC for manganese.

Nickel concentrations in the soils of the eastern United States range from <5 to 700 ppmwith a mean of 11 ppm or an estimated arithmetic mean of 18 ppm. The local USGS soilsampling showed an average nickel level of about 10 ppm. The mean concentration inChristina River sediment samples was 28 ppm and there was no trend of increasingconcentrations at the near-Site river stations. The North and South Disposal site nickelconcentrations averaged 34 ppm and showed no evidence of anthropogenic loading since allthe enrichment factor values were low.

The surface water concentrations of nickel did not exceed the WQC and are unlikely to betoxic to the aquatic biota at the Du Font-Newport Site.

In summary, these results provide little compelling evidence to include aluminum, arsenic,iron, manganese and nickel as constituents of concern for the Du Font-Newport EE.

5.4 TOXICITY PROFILES

Toxicity profiles were prepared for the seven ecological constituents of concern for theNewport Site EE identified in Section 5.3. To the extent possible with existing literature,information on chemistry, environmental fate, residues in environmental media andecological toxicity were compiled for each of the constituents of concern.

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5.4.1 Barium

Aquatic Ecosystems

Environmental toxicity data for barium are extremely limited. No WQC have beenestablished because "the physical and chemical properties of barium generally will precludethe existence of the toxic soluble form under fresh water conditions (USEPA 1986). TheWQC (USEPA, 1986) states that "experimental data indicate that the soluble bariumconcentration in fresh and marine water generally would have to exceed 50 ppm beforetoxicity to aquatic life would be expected. Recognizing that the physical and chemicalproperties of barium generally will preclude the existence of the toxic soluble form underusual freshwater or marine conditions, a restrictive criterion for aquatic life appearsunwarranted."

Chemistry and Environmental Fate. Barium is a silver white metal produced by reactionof barium oxide. The primary source is the mineral barite (BaCO3). Barium is iin water but soluble in alcohol. Most barium compounds are soluble in water.

Residues. Wallace et al, (1982) reported the mean barium concentrations measured in plantspecies from the Savannah River Plant flood plain as follows: water tupelo (Nyssaaquatica). 273 ppm; duck potatoe (Saggitaria latifolia). 110 ppm; and cattails (Typhalatifolia). 134 ppm.

Rawlence and Whitton (1977) studied elements in aquatic macrophytes in lakes in NewZealand. Barium concentrations ranged from 100 - 220. ppm. No correlation could be madefor barium levels in sediments and measurements in plants. For example, barium averaged160 ppm in sediments where plant tissues measured 220 ppm; sediments with average levelsof 650 ppm corresponded to levels of 100 ppm in plants.s

In comparison to the above references, barium concentrations in plant tissues (roots,rhizomes and leaves) of spatterdock from the Newport Site wetlands were high, rangingfrom 75.4 - 7960 ppm dry weight.

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Finerty et al, (1990) studied metal residues in tissues of crayfish in southern Louisiana.Although both absorption and retention of barium is low, it is most often deposited in theexoskeleton. High metal concentrations in sediments did not necessarily correspond to highmetal concentrations in crayfish. However, element concentrations (barium, lead andnickel) in abdominal muscle tissue significantly related to percent mica in sediment.

Ecotoxicity. Limited data are available on barium ecotoxicity, possibly due to the lowsolubility of barium and its tendency to precipitate as a salt; that precludes bioavailabilityand toxicity.

According to the EPA, experimental data indicate that soluble barium concentrations infresh and marine waters generally would have to exceed 50,000 ppb before toxicity toaquatic life would be expected (U.S. EPA 1986). The highest level of barium in non-filteredsurface waters was 1,570 ppb collected from the South Disposal site ditch at Station AS05,and would not be expected to be toxic to freshwater aquatic life.

Even though the barium ion, Ba+2, is extremely toxic when absorbed, barium sulfate(BaSO4), the form found in lithopone as well as the form commonly found in theenvironment, is so slightly soluble that it is nontoxic (API 1970). The toxicity of orallyingested soluble barium salts in various mammals is also low compared to many otherelements such as lead, cadmium, and mercury. Only small quantities (up to 40 ppm) ofbarium are typically found in most plants, as barium is generally considered to be toxic tomost plants at low concentrations. Based on the plant tissue analyses at the Du Font-Newport site, barium appears to be able to accumulate to fairly high levels in the roots andrhizomes of spatterdock (see Table C-21). The form in which barium would occur in theroots and rhizomes of spatterdock are unknown as is the potential for animals to suffer toxiceffects from eating these plants. The National Academy of Science (NAS) recommends thatthe levef of soluble barium in a domestic animal's diet should not exceed 20 ppm (NAS1980). *;

The manufacture of Lithopone, a pigment composed of 30 percent barium sulfate and 70percent zinc sulfide is known to cause baritosis (a benign pneumoconiosis) in workers (API

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1970). Exposure of guinea pigs to barite dust has produced nodular granulation of the lungscharacteristic of baritosis (API 1970). Studies on chronic inhalation of barium sulfate in ratsindicates that baritosis is not associated with fibrosis, and appears to be due to accumulationof alveolar macrophages and reversible hyperplasia of the bronchial epithelium (Klaassenet al, 1986).

5.4.2 Cadmium

Chemistry and Environmental Fate. Cadmium is a relatively rare element that isconcentrated in zinc-bearing sulfide ores. It occurs in the earth's crust at a concentrationaround 0.15 ppm. Compared to other metals cadmium is relatively mobile in the aquaticenvironment. Sorption processes are important in determining transport, partitioning andpotential for remobilization. In polluted waters, complexing with organic materials is thedetermining factor in environmental fate (Versar, 1979).

In aquatic systems, cadmium is present in the free, readily bioavailable, divalent form (up to pH 8. Cadmium begins to hydrolyze at pH 9 forming cadmium (OH)2. Cadmiumis available for sorption onto suspended solids and complexation with organic matter andis transported in these forms.

Residues, Adsorption and desorption are the most important factors in controlling theconcentration of cadmium in water. Adsorption and desorption rates are rapid on mudsolids, and particles of clay, silica, and mimic material (Eisler, 1985). No obvious trend infiltered versus nonfiltered cadmium concentrations was observed in surface water samplescollected at the Du Font-Newport Site. The decomposition of aquatic plants which haveaccumulated cadmium from sediments may release the metal into water.

Background levels of cadmium in uncontaminated media are variable. Concentrations infreshwater range from 0.05 to 0.2 ppb (Eisler, 1985). Maximum dissolved levels measuredin surface waters in the Site vicinity are generally below detection. In freshwater sediments,cadmium residues are also highly variable and can range from less than 0.1 ppm to 3000ppm dry weight. In highly contaminated areas concentrations can range up to 50,000 ppm

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(Moore and Ramamoorthy, 1984). The highest sediment cadmium concentration in theDu Font-Newport Wetlands Investigation was 77 ppm in the South Disposal site pond.

Presence of manganese and iron may inhibit uptake of cadmium in aquatic plants (Mooreand Ramamoorthy, 1984). Manganese and iron are prevalent at high levels in the sedimentsat the Newport Site, and were found in relatively high concentrations in all spatterdocktissues from the Newport wetlands. Cadmium levels in spatterdock collected from theNewport wetlands did not concentrate in any tissue above the levels for cadmium insediment.

Cadmium tends to accumulate in major organ tissues of fish, particularly liver and kidneysrather than muscle. In general, residues in fish cannot be correlated to concentrations inwater or feeding habits (Moore and Ramamoorthy, 1984). Levels of cadmium detected inthe whole body fish collected for the Phase HI investigation were above trace concentrations(WCC, 1990).

Unlike aquatic biota, investigations with terrestrial animals have shown that under naturalconditions absorption of cadmium from the gastrointestinal tract is poor and hence,poisoning is unlikely. However, in contaminated areas cadmium can result in toxic effectsin mammals through ingestion of contaminated vegetation. Contaminated grass (9 ppm) wasblamed for the death of a horse (Goodman and Roberts, 1971). Thirty to 60 ppm in thediet of sheep for 191 days resulted in reduced growth and feed intake (Doyle et al, 1972).

Ecotoxicity. In general, mortality due to exposure to cadmium increases with increasedexposure time, decreased water hardness and decreased organism age. Cadmium toxicityto aquatic plants is less than copper, and similar to lead, nickel and chromium. IncreasingpH resulted in increased mortality in a wide variety of aquatic plant species. Inhibitions togrowth can occur at 0.02 - 1.0 ppm (Moore and Ramamoorthy, 1984). Eisler (1985)reported that concentrations greater than 10 ppb are associated with high mortality, reducedgrowth and inhibited reproduction in plants.

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Canton and Slooff (1982) conducted toxicity studies with cadmium chloride on freshwaraorganisms of different trophic levels. As a result of their investigation they proposed aWQC of 0.1 ppb. The EPA chronic WQC is currently 1.1 ppb based on a water hardnessof 100 ppm CaCO3. Their study also showed that bioavailability of cadmium is highlydependent on water hardness.

In 96-hour LC static bioassays, Mackie (1989) showed that cadmium is the most toxic ofthree metals (aluminum, cadmium and iron) tested on four functional groups (filter feeders,scrapers, shredders, predators). The most sensitive species tested was the shredder H.azteca. Mackie (1989) also studied the effect of hydrogen ion content on the toxicity ofcadmium.

The 96 hour LC 's for several invertebrate species as given in Elder (1990) are as follows:Gammarus pulex (120 ppb and 680 ppb): Limnodrilus hoffrneisteri (170 ppb); and Asellusaquaticus (1320 ppb).

Acute effects to freshwater biota from cadmium exposure range from 0.6 ppb (96-hr IVVfor juvenile chinook salmon to 6.6 ppb for two month old rainbow trout (Table 18) (Eisler1985). LCso's for fish known to occur in the Site vicinity are: goldfish, 748 ppb (Elder 1990)and 12,600 ppb (Connell and Miller 1984), channel catfish 4480 ppb, and bluegill 6470 ppb(Elder 1990).

While cadmium concentrations in unfiltered water samples collected from the North andSouth Disposal sites, and the Christina River are well below the LC 's for fish known tooccur in the area, some cadmium results are above the WQC (adjusted for Site-specifichardness values). The acute and chronic WQC for cadmium in the North Disposal sitedrainageway are 3.92 and 1.13 ppb, respectively. Unfiltered surface water collected atAW05 arid AS09 are above the acute cadmium WQC. The acute and chronic cadmiumWQC at the South Disposal site pond are 7.75 and 1.82 ppb, respectively. Surface watercollected from the drainage ditch at AS05 contained cadmium at a level between the chronicand acute WQC. The sample collected from the Christina River at the James Street Bridge

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also fell between the hardness specific chronic (1.4 ppb) and acute (5.4 ppb) cadmium WQCfor the Christina River.

Therefore, using Site-specific WQC, acute effects may be expected to freshwater aquatic lifeat the North Disposal site pond (AW05) and ditch (AS09), and sub-lethal effects may beexpected at the South Disposal site drainage ditch (AS05).

Most studies of cadmium have been designed to define the effects of high intakes, generallyin a short period of time, rather than to establish no-effect levels. With an adequate diet,5 ppm dietary cadmium is the level at which gross adverse effects are most apt to begin indomestic animals (NAS 1980). Higher levels of cadmium produce a wide range of changesin metabolic measurements that have been observed in one or more species. High intakesof cadmium in the diet can cause reduced growth rates, anemia, enteropathy, kidneydamage, infertility, deformed fetuses, abortions, and hypertension (NAS 1980). Mostinformation about cadmium's biological behavior shows it to be toxic and an antagonist ofseveral essential minerals, such as zinc, iron, copper, and calcium (NAS 1980). With highlevels of dietary zinc, the effects of cadmium are known to be lessened. Vitamin C has alsobeen shown to markedly decrease the toxicosis produced by cadmium (NAS 1980). Adietary concentration of 0.5 ppm is the maximum recommended level for domestic animals(NAS 1980).

5.43 Chromium

Chemistry and Environmental Fate. Based on disposal history of the Site, chromium hi thelandfills occurs in trivalent +3 form, the most common form which it occurs hi theenvironment. Hydrolysis and precipitation are most important processes that determine thefate and effects of chromium. The processes of adsorption and bioaccumulation arerelatively minor. Suspended particulates are a major source of environmental transport ofchromium in aquatic systems (Eisler, 1986).

Residues. Dissolved concentrations of chromium in unpolluted freshwaters range fromapproximately 1 to 2 ppb (Moore and Ramamoorthy, 1984). Dissolved chromium

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concentrations in the surface waters in the vicinity of the Du Font-Newport Site are allbelow the method detection limit.

Sediment chromium concentrations from industrial zone waters can be as high as 1337 ppmdry weight, but generally fall below 1000 ppm (Moore and Ramamoorthy, 1984). Much ofthis chromium is not bioavailable.

Residuals of chromium in plants from freshwater industrial zone sources generally range upto 50 ppm dry weight and in unpolluted areas seldom exceed 5 ppm (Moore andRamamoorthy, 1984). Results of analyses of spatterdock roots at the Du Font-Newport Siteranged from 3.58 - 5.48 ppm dry weight.

Residuals in invertebrates from polluted freshwater generally range up to 25 ppm dry weightas compared with < 5 ppm reported for unpolluted water. Rate of uptake is greater inyoung specimens and residues decline with age of the specimen reflecting rapid metabolism.

Chromium does not normally accumulate in fish. Concentrations in muscle tissue fro:freshwater fish generally fall below 0.25 ppm dry weight (Moore and Ramamoorthy, 1984).'This is true for fish tissue analyzed from the Christina River (WCC, 1990).

Ecotoxicity. The trivalent form of chromium is an essential element to mammals (Eisler,1986). Chromium has lower toxicity than other metals considered in this investigation.

Acute toxicity to freshwater invertebrates is highly variable. Chronic effects includedecreased growth and body size. Toxicity may be influenced by the presence of othermetals. Fish are generally less susceptible to the toxic effects of chromium thaninvertebrates. Ninety-six hour acute LC values for chromium +3 generally range from2,000 to 3,200 ppb for sensitive freshwater organisms (Eisler 1986).

Specific acute LC 's for chromium +3 for fish (96-hour) are for fathead minnow, 5,070 to67,400 ppb, and rainbow trout, 4,400 ppb (Eisler 1986). Ninety-six hour chronic LC forchromium +3 given by ERA (1986) for fathead minnow is 1025 ppb. The highest to;

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chromium value in surface water was in a sample collected in the South Disposal sitedrainageway (15.2 ppb).

Maximum acceptable toxicant concentration (MATC) values represent the highestconcentration tested having no significant adverse effect on survival, growth and/orreproduction, and the lowest concentration at which these effects were observed. MATCvalues in freshwater fish range from 51 to 105 ppb in rainbow trout to as high as 1,000 to3950 ppb in fathead minnow (Table 18). MATC values for chromium +3 for rainbow troutrange from 30 to 157 ppb. The highest level of total chromium was detected in the SouthDisposal site drainageway (AS05) at 15.2 ppb.

Chromium +3 which is typically found in the environment, has a low order of toxicity. Thetoxicity of chromium + 3 when administered by oral dosage has been studied very little. Fewcases of acute systemic intoxication by chromium in animals have been reported (NAS1980). Doses of up to 650 ppm-BW chromium +3 in rats have produced no overt toxicosisand levels of up to 1000 ppm supplementary chromium +3 produced no effects in chicks(NAS 1980). Maximum tolerable dietary levels for domestic animals are set at 3000 ppmchromium as the oxide and 1000 ppm as the chloride (NAS 1980).

5.4.4 Copper

Chemistry and Environmental Fate. Copper is widely distributed in nature in its free stateand in sulfides, arsenides, chlorides and carbonates. It has a variety of differing propertiesdepending on which of its many states it occurs. Oxidation state +2 is the most common.Copper is insoluble hi water but soluble in some acids. Formation of ion complexes,sorption (to hydrous metal oxides, clays and organic materials) and bioconcentration can beimportant processes in the environmental fate of copper. Redox potential, pH,concentrations of organic materials and adsorbents, availability of iron and manganeseoxides, biological activity and competition with other metals are all determinants of theaquatic fate of copper. In organic rich environments, the control of dissolved copperconcentrations is generally competition between organic complexing in solution and sorptiononto clay and paniculate organic material.

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Residues. Soluble copper levels in freshwaters range from about 0.5 to 1.0 ppb inuncontaminated areas to more than 2.0 ppb in urban areas (Moore and Ramamoorthy,1984). In the Du Font-Newport study area, the highest dissolved level of copper was 7.6 ppbin the surface waters of the South Disposal site pond._——•Uncontaminated freshwater sediments generally contain concentrations less than 20 ppm.Concentrations on the order of 1000 ppm are typical of aquatic sediments in areascontaminated with mine wastes (Moore and Ramamoorthy, 1984). Maximum concentrationsmeasured in the North and South Disposal site drainageways were 1386.6 ppm and 781.6ppm, respectively. The TVG for copper is 136 ppm.

Concentrations of copper in attached aquatic plants in polluted waters average 10-100 ppmdry weight (Moore and Ramamoorthy, 1984). Similarly, concentrations of copper in theroots of spatterdock from the South Disposal site wetlands contained 12.3 - 121 ppm dryweight. o

n ofSeveral field studies have shown that there is no bioaccumulation or biomagnificationcopper through the food chain. For example, concentrations in herbivorous, omnivorous andcarnivorous invertebrates from a polluted stream averaged 13.7, 70.9 and 30.5 ppm,respectively (Andersen, 1977). Uptake by benthic species is directly related to levels insediment (Moore and Ramamoorthy, 1984).

Moore and Ramamoorthy (1984) report that muscle tissue of fish from polluted freshwatersseldom exceed 1 ppm. Fish fillet tissue analyzed for the Supplemental Phase III did notexceed 1 ppm (WCC, 1990).

Ecotoxicitv. Soluble copper is highly toxic to most aquatic plants. Inhibition of growthgeneraU ^ t concentrations as low as 0.1 ppm. Orjty mercury is more toxic. Manyspecies of algae develop a tolerance to copper thereby increasing copper in the food chain(Moore and Ramamoorthy, 1984). For invertebrates, LC is generally less than 0.5 ppm.The 96-hour LC for Chironomus tentans and Asellus aquaticus is 0.3 and 9.21 ppm,



respectively (Elder, 1990). Some invertebrate species adapt to high levels (Moore andRamamoorthy, 1984).

Similar to toxicity in plants, copper is more toxic to fish than any other metal exceptmercury. Acute toxicity (96-hour LC values) of copper to juvenile northern squawfish (awestern species) was 23 ppb, while that of the bhintnose minnow was 230 ppb, and acutecopper LC 's to rainbow trout ranged from 190 to 210 ppb. Acute LC values for thepumpkinseed; a fish found in the Site vicinity, ranged from 1240 to 1670 ppb for juveniles,and 1740 to 1940 ppb for adults (Connell and Miller, 1984) (Table 18). Chronic toxicity,values range from 3.873 ppb for brook trout to 60.36 ppb for northern pike (EPA, 1986).Chronic effects of copper to fish are reduced growth and rate of reproduction, andbehavioral changes. Site-specific WQC values (adjusted for hardness) for the NorthDisposal site drainageways range from 11.8 ppb for chronic, to 17.7 for acute effects tofreshwater biota. Total copper in unfiltered water from one sample from the NorthDisposal site pond (AS05) exceeded this chronic WQC, and one sample from the NorthDisposal site drainageway (AS09) exceeded the acute WQC for copper.

For the South Disposal site, the hardness specific acute and chronic WQC for copper are31.3 and 19.8 ppb, respectively. Unfiltered water collected from two locations in the SouthDisposal site drainageway exceeded the chronic WQC.

Copper is highly toxic to roots of vascular plants but only minimally trans-located to above-ground structures (Bennett, 1971). Chlorosis of leaves (yellowing) is one symptom ofsublethal copper toxicity and has been shown to occur in sandy soils with concentrations inexcess of 150 ppm and pH 5.0 (Reuther and Smith, 1-953).

Terrestrial: Species vary widely in susceptibility to copper toxicity, in part due to differencesin sulfur metabolism as well as differences in concurrent levels of sulfur, molybdenum, zinc,iron, and selenium. The effects of copper toxicosis when it does occur are not alwaysobvious and include growth inhibition, anemia, muscular dystrophy, impaired reproduction,and decreased longevity (NAS 1980). The maximum tolerable levels of dietary copperduring growth of various species approximate the following under normal levels of

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molybdenum, sulfate, zinc, and iron: chickens, 300 ppm; turkeys, 300 ppm; rabbits, 200ppm; and rats, 1000 ppm (NAS 1980). The minimal lethal dose of copper for bird and fowlspecies varies from 300-1550 on a ppm-BW basis depending on the form of copper fed(NAS 1977). Mallards have been shown to tolerate 29 ppm-BW (NAS 1977).

Sheep are particularly sensitive to copper intoxication. Regular, dietary intake of copper-contaminated forage and soil in excess of 15 ppm was found to be lethal (Hemkes andHartmans, 1973). Contamination of feeds with copper leads to accumulation in tissues,especially the liver (Underwood, 1971). In contrast, studies r« irted that for othermammals, copper toxicity is of little significance since they possess 'arriers to absorption(Gough et al, 1979).

5.4.5 Lead

Chemistry and Environmental Fate. Lead from the atmosphere, carried via precipitationand runoff, is a primary source to aquatic systems. Partitioning of lead between aquand solid phases depends on sediment geochemistry, temperature, pH, redox potential,ionic competition. Solubility of lead is low in water because it requires low pH, low organiccontent, and low concentrations of suspended sediments. The portion of the lead that is notwater soluble is adsorbed to sediment. Lead concentrates in clay and organic matter (Baudoet al, 1990).

Residues. Most lead discharged into surface waters is rapidly adsorbed onto sediments.Concentrations of soluble lead in uncontaminated freshwaters are generally less than 3 ppb.In industrial zone rivers and receiving waters of liquid mine wastes concentrations of leadcan reach more than 500 ppb (Moore and Ramamoorthy, 1984). The maximumconcentration of dissolved lead measured in the Du Font-Newport study area surface waterswas 5.6 ppb in the North Disposal site drainageway.

In uncontaminated areas, sediment concentrations can range from 2 to 50 ppm dependingon the composition of the underlying bedrock. Municipal/industrial zone rivers can producesediment concentrations on the order of 50 to 500 ppm (Moore and Ramamoorthy, 198

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Sediment lead levels were high throughout the area sampled, including the field referencestation. Maximum concentrations were measured in the North Disposal site drainageway(27,000 ppm).

High levels of lead residues are reported hi attached plants inhabiting polluted waters.There is a correlation between lead levels in water and plant tissues. Several species havebeen used to monitor contamination levels. Few studies have been done on the interactionof sediments and plant residues (Moore and Ramamoorthy, 1984). A correlation could notbe made between lead levels in sediments and spatterdock collected from the SouthDisposal site wetlands.

Benthic invertebrates do not concentrate lead from algal food or water. Little accumulationis found at higher trophic levels. Variability in sorption is species dependent. Similarly,little accumulation of lead is found in freshwater fish (Moore and Ramamoorthy, 1984).Lead was detected in whole fish sampled from the Christina River at predictable levels forurban streams (WCC, 1990).

Ecotoxicity. Lead is a mutagen and teratogen when absorbed in excessive amounts.Although it is ubiquitous and is a trace constituent in soils, water, plants, animals, and air,lead is neither biologically essential nor beneficial to living organisms.

Lead is less toxic to aquatic plants than mercurials and copper. Acute and chronic planteffects appear at surface water concentrations of 0.1-5 ppm. Manganese and copper mayaffect lead induced inhibitions. Some plant species are relatively tolerant of lead.

Lead is less toxic to invertebrates than copper, cadmium, and zinc. Acute effects arereported at 0.1-10 ppm. However, significant mortality may occur within the range of 0.002-670 ppm (Moore and Ramamoorthy, 1984). Some isopods and polychaetes are particularlyresistant. Chronic affects may not appear at concentrations below the LC . The 96-hourLCjo for Asellus aquaticus is 64.1 ppm (Elder, 1990). Mackie (1989) found that the acutetoxicity of lead decreases at higher pH levels for the bivalve. Pisidium casertanum and theamphipod, Hyalella azteca.

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Hardness-specific WQC for lead are 81.7 ppb acute, and 3.2 pp chronic for the NorthDisposal site drainageway, 99.5 ppb acute and 3.9 ppb chronic for the South Disposal sitedrainageway, and 117.4 ppb acute and 4.6 ppb chronic for the Christina River. Of sevenunfiltered surface water samples collected in the North Disposal drainageway, six exceededthe chronic WQC and one water sample exceeded the acute WQC for lead. Six out of nineunfiltered surface water samples collected in the South Disposal site pond and drainagewayexceeded the Site-specific chronic lead WQC, while two of the nine samples exceeded theacute WQC. The mean lead level from 12 water samples collected in the Christina Riverover a tidal cycle also exceeded the chronic lead WQC.

Ninety-six hour LC 's for rainbow trout exposed to lead range from 1200 ppb (dissolvediron) in soft water (28 ppm CaCO3), to 506,500 ppb (total iron) in hard water (355 ppmCaCO3). Acute lead toxicity is inversely proportional to water hardness (Sorensen, 1991).Brook trout exhibited a 96-hour LC of 4100 ppb when exposed to total iron in soft water(44 ppm CaCO3) (Eisler, 1988). Fathead minnows exposed to lead for 96-hours have shqan LCso of 2400 ppb (Sorensen, 1991).

MATC values for lead range from 70 to 120 ppb for bluegill in soft water (41 ppm CaCO3),75 to 136 for channel catfish (36 ppm CaCO3), and 119 to 253 ppb for white sucker (34 ppmCaCO3) exposed during lifetime tests (Eisler 1988). For hard waters, MATC values are 120to 360 ppb for rainbow trout (353 ppm CaCO3).

Toxicity of lead to terrestrial plants results in reduced growth. Most lead in soils is poorlysoluble with low uptake in roots. Lead adsorbed on forage plants from aerial deposition canbe toxic to grazing animals. Lead values in pasture-grasses ranging up to 2,800 ppm dryweight have resulted in chronic debilitation of horses and cattle (Schmitt et al, 1971).

Clinical toxicosis in animals exposed chronically to lead is indirect and probably resultsthrough interference in normal metal-dependent enzyme functions at specific cellular sitescharacterized by apparent clinical abnormalities in hematological, neural, renal, or skeletalsystems (NAS 1980). Lead toxicosis in animals may be complicated by simultaneousexposure to excessive mercury, cadmium, zinc, copper, or other microelements. Total mi

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