Woodward-Clyde Consultants - Superfund Records · PDF fileWoodward-Clyde Consultants Engineering & sciences applied to the earth & its environment May 28, 1992 88C2076-4W Mr. Brandt

•>»».'

Woodward-ClydeConsultantsEngineering & sciences applied to the earth & its environment

May 28, 1992 o „88C2076-4W /Sfc „, 'J

Mr. Randy SturgeonEnforcement Project ManagerU.S. Environmental Protection AgencyRegion 3841 Chestnut StreetPhiladelphia, PA 19107

Re: Final Remedial Investigation ReportDu Font-Newport SiteNewport, Delaware

Dear Mr. Sturgeon:

On behalf of Du Pont, Woodward-Clyde Consultants (WCC) is pleased to submit tothe USEPA via courier six copies of the Final Remedial Investigation Report. Thisreport is presented in two volumes. Volume 1 contains the text, tables, and figures;Volume 2 contains Appendices A through J. We believe this document satisfies thereporting requirements of the EPA and the July 22, 1988 Administrative Consent Orderfor the Remedial Investigation performed at the Du Pont-Newport Site.

This report also addresses EPA's comments regarding the Phase in RI Data SufficiencyReport (WCC, May 17, 1991) that were submitted to Du Pont on August 16, 1991, aswell as EPA's comments regarding the Draft Remedial Investigation Report (WCC,November, 1, 1991) that were provided in submittals to Du Pont on December 16, 1991,February 11, 1992, and March 20, 1992.

5120 Butler Pike • Plymouth Meeting, Pennsylvania 19462215-825-3000 • Fax 215-834-0234 fi R 3 I U I 3 I

1Woodward-ClydeConsultants

Mr. Randy SturgeonU.S. Environmental Protection AgencyMay 28, 1992Page 2

Please do not hesitate to call Mr. Roger Gresh at WCC or Mr. Joel Karmazyn atDu Pont if you have any questions.

Very truly yours,

lames P. BuczalaAssistant Project Geologist

Roger T. Gresh, P.G.AssociateProject Manager

RTG/kcs/DPN4encl.

Distribution:

M. Springer, EPAH.R. Preston, EPAD. Henne, Dept. Int. (2)P. Knight, U.S. Fish.& WildlifeA. Killer, DNREC (3)S. Sury, CIBA-GEIGYG. Wise, CIBA-GEIGYM. Watson, CIBA-GEIGYB. Butler, Du PontJ. Karmazyn, Du PontC. Trmal, Du PontN. Griffiths, Esq., Du PontG. Foley, Du PontA. Hirsch, WCC

Woodward-ClydeConsultantsEngineering & sciences applied to the earth & its environment

May 28, 199288C2076-4W

Mr. Brandt ButlerDu Pont Chemicals1007 Market Street, Room 12228Wilmington, Delaware 19898

Re: Final Remedial Investigation ReportDu Pont-Newport SiteNewport, Delaware

Dear Mr. Butler:

Woodward-Clyde Consultants (WCC) is pleased to present the report referenced above,dated May 28,1992. This document has been peer reviewed in keeping with the WCCCorporate Quality Assurance policy. Besides overseeing all of the Phase III design andfield work, I have also personally reviewed the contents with regard to the hydrogeologicinformation obtained and reported in previous reports by WCC for the Du Pont-NewportSite. The interpretations and judgements herein, in my opinion, are consistent with thestandards of technical practice for these services.

Thank you for your continuing confidence in Woodward-Clyde Consultants.

Very teuly yo

ROGER T. GRESHReg. No. 452

Rog r T. Gresh, P.O.AssociateDelaware Registered Professional Geologist No. 452

RTG/kcs/DPN4encl.

»

cc: R. Sturgeon, EPA J. Karmazyn, Du PontM. Springer, EPA C. Trmal, Du PontH.R. Preston, EPA N. Griffiths, Esq.D. Henne, Dept. Int. G. Foley, Du PontP. Knight, U.S. Fish & Wildlife A. Hirsch, WCCA. Killer, DNRECS. Sury, CIBA-GEIGYG. Wise, CIBA-GEIGYM. Watson, CIBA-GEIGY

5120 Butler Pike • Plymouth Meeting, Pennsylvania 19462215-825-3000 • Fax 215-834-0234 A R 3 I I 3

FINAL VOLUME 1 OF 2

REMEDIAL INVESTIGATION REPORTDUPONT-NEWPORT SITENEWPORT, DELAWAREMAY 28, 1992

For:

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

Prepared for:

E.I. du Pont de Nemours and Company, Inc.Du Pont ChemicalsRoom 122281007 Market StreetWilmington, DE 19898

Prepared by:

Woodward-Clyde Consultants5120 Butler PikePlymouth Meeting, PA 19462

Project No. 88C2076-4W

HR3UI3I*

Woodward-ClydeConsultants

TABLE OF CONTENTS

Section Page No.

VOLUME 1

EXECUTIVE SUMMARY ES-1

1.0 INTRODUCTION 1-1

1.1 PURPOSE OF THE REMEDIALINVESTIGATION REPORT 1-1

1.1.1 Initial Investigations (1975 to 1986) 1-21.1.2 Remedial Investigation Phases 1-3

1.2 PREVIOUS REPORTS 1-31.3 SITE HISTORY 1-8

1.3.1 Lithopone 1-101.3.2 CPC and QA 1-101.3.3 Titanium Metal 1-121.3.4 Thoria Dispersed Modified Nickel 1-12

2.0 FIELD INVESTIGATIONS 2-1

2.1 MONITORING WELL INSTALLATION 2-12.2 GROUNDWATER SAMPLING 2-2

2.2.1 Monitoring Wells 2-22.2.2 Groundwater Seepage 2-32.2.3 Residential Wells 2-4

2.3 RIVER WATER SAMPLING 2-52.4 SOIL INVESTIGATIONS 2-52.5 BOREHOLE GEOPHYSICS 2-72.6 SURFACE SURVEYS 2-9

AR3UI35


TABLE OF CONTENTS - continued

Section Page No.

2.6.1 Soil Gas Survey 2-92.6.2 Surface Geophysical Surveys 2-92.6.3 Radiometric Surveys 2-9

2.7 A» CR TESTING 2-102.8 Wi OS INVESTIGATIONS 2-11

2.8., 31 Wetlands Investigation 2-112.8.1 s n Wetlands Investigation 2-122.8.3 ,e in Wetlands Investigation 2-122.8.4 plemental Phase III Wetlands

estigation 2-13

3.0 PHYSICAL CHARACTERISTICS 3-1

3.1 ENVIRONMENTAL SETTING OF THE SITE3.2 ECOSYSTEMS

3.2.1 Christina River 3-33.2.2 Wetlands 3-53.2.3 Terrestrial Habitats 3-73.2.4 Sensitive Habitats 3-7

3.3 HYDROGEOLOGY 3-8

3.3.1 Regional Geology 3-83.3.2 Newport Site Geology 3-93.3.3 Regional Hydrogeology 3-123.3.4 Site Hydrogeology 3-14

3.3.4.1 Hydrostratigraphic Units 3-153.3.4.2 Tidal Influences on Piezometric

and Potentiometric Surfaces 3-16.3.4.3 Groundwater Flow 3-173.3.4.4 Aquifer Characteristics 3-20

11



Section Page No.

4.0 CHEMICAL CONSTITUENT SOURCEAND DISTRIBUTION 4-1

4.1 SOIL 4-24.2 GROUNDWATER 4-8

4.2.1 Chemistry Contours by Sampling Event 4-94.2.2 Distribution Patterns and Sources 4-94.2.3 Vertical Hydraulic Gradient Impacts 4-134.2.4 Groundwater Seepage 4-144.2.5 Residential Wells 4-15

4.3 SURFACE WATER 4-16

4.3.1 North Disposal Site Draraageways 4-174.3.2 South Disposal Site Pond and

Drainageway 4-174.3.3 Christina River 4-18

4.4 SEDIMENT 4-20

4.4.1 Sediment Chemistry 4-20

4.4.1.1 North Disposal Site Drainageways 4-224.4.1.2 South Disposal Site Pond and

Drainageways 4-234.4.1.3 Christina River 4-24

4.4.2 Sediment Toxicity Tests 4-276

4.5 BIOLOGICAL TISSUES 4-27

m

RR31M37



.Section Page No.

5.0 CHEMICAL CONSTITUENT FATEAND TRANSPORT 5-1

5.1 GROUNDWATER 5-15.2 SURFACE WATER TRANSPORT 5-9

5.2.1 Storm Water Run-Off 5-95.2.2 Tidal Flushing 5-11

5.3 SEDIMENTS 5-12

5.3.1 Wetland Sediment 5-125.3.2 Christina River Sediments 5-12

5.4 BIOTA

5.4.1 Bioconcentration of Metals5.4.2 Metal Transfer Between

Trophic Levels 5-14

6.0 SUMMARY AND CONCLUSIONS 6-1

IV



LIST OF TABLES

TABLE 1 NORTH DISPOSAL SITE WASTE DISPOSALINVENTORY

TABLE 2 MONITORING WELL GROUPINGSPHASE III REMEDIAL INVESTIGATION

TABLE 3 GROUNDWATER SAMPLING SUMMARYPHASE I REMEDIAL INVESTIGATION

TABLE 4 GROUNDWATER SAMPLING SUMMARYPHASE II REMEDIAL INVESTIGATION

TABLE 5 GROUNDWATER SAMPLING SUMMARYPHASE HI REMEDIAL INVESTIGATION

TABLE 6 GROUNDWATER SEEPAGE SAMPLING SUMMARYPHASE III REMEDIAL INVESTIGATION

TABLE 7 SOIL BORING/SAMPLE SUMMARYREMEDIAL INVESTIGATION

TABLE 8 SUMMARY OF STATIONS SAMPLED IN THEWETLANDS INVESTIGATIONS

TABLE 9 HYDROSTRATIGRAPHIC UNITSREMEDIAL INVESTIGATION REPORT

TABLE 10 BACKGROUND METAL CONCENTRATION(RANGES IN MG/KG)

TABLE 11 SUMMARY OF PARAMETERS IDENTIFIED,GROUNDWATER SEEPAGE

AR3UI39



LIST OF FIGURES

FIGURE 1 REGIONAL LOCATION PLAN

FIGURE 2 MONITORING WELL LOCATION PLAN

FIGURE 3 LITHOPONE PRODUCTION ACTIVITIES, 1938

FIGURE 4 CPC AND QA PRODUCTION ACTIVITIES

FIGURE 5 OTHER HISTORICAL PRODUCTION ACTIVITIES

FIGURE 6 RESIDENTIAL WELL LOCATIONS

FIGURE 7 SOU. SAMPLE AND CROSS-SECTIONLOCATION PLAN

FIGURE 8 BALLFIELD SAMPLE LOCATION PLAN

FIGURE 9 REMEDIAL INVESTIGATION SURVEYS

FIGURE 10 CHRISTINA RIVER SAMPLING STATIONS

FIGURE 11 WETLAND SAMPLING STATIONS

FIGURE 12 WETLAND BOUNDARIES

FIGURE 13 LAND USE ADJACENT TO SITE

FIGURE 14 STRATIGRAPHIC CROSS-SECTION H-H'

FIGURE 15 STRATIGRAPHIC CROSS-SECTION I-P

FIGURE 16 PRELIMINARY CONCEPTUAL GROUNDWATERMANAGEMENT ZONE

VI



LIST OF FIGURES - continued

FIGURE 17 PIEZOMETRIC SURFACE IN FILL/OTHERQUATERNARY ZONE, HIGH TIDE - 12/11/90

FIGURE 18 PIEZOMETRIC SURFACE IN FELL/OTHERQUATERNARY ZONE, LOW TIDE - 12/13/90

FIGURE 19 PIEZOMETRIC SURFACE - SHALLOW ZONE ANDCOLUMBIA WELLS, FILL/OTHER QUATERNARYZONE, HIGH TIDE - 12/11/90

FIGURE 20 PIEZOMETRIC SURFACE - SHALLOW ZONE ANDCOLUMBIA WELLS, FILL/OTHER QUATERNARYZONE, LOW TIDE - 12/13/90

FIGURE 21 POTENTIOMETRIC SURFACE - INTERMEDIATEZONE, HIGH TIDE - 12/11/90

FIGURE 22 POTENTIOMETRIC SURFACE - INTERMEDIATEZONE, LOW TIDE - 12/13/90

FIGURE 23 POTENTIOMETRIC SURFACE - DEEP ZONE,HIGH TIDE - 12/11/90

FIGURE 24 POTENTIOMETRIC SURFACE - DEEP ZONE,LOW TIDE - 12/13/90

FIGURE 25 GROUNDWATER FLOW DIRECTIONS - SHALLOWZONE AND COLUMBIA WELLS, FILL/OTHERQUATERNARY ZONE, HIGH TIDE - 12/11/90

FIGURE 26 GROUNDWATER FLOW DIRECTIONS - SHALLOWZONE AND COLUMBIA WELLS, FILL/OTHERQUATERNARY ZONE, LOW TIDE - 12/13/90

vu

AR31UU




FIGURE 27 GROUNDWATER FLOW DIRECTION -INTERMEDIATE ZONE, HIGH TIDE - 12/11/90

FIGURE 28 GROUNDWATER FLOW DIRECTION -INTERMEDIATE ZONE, LOW TIDE - 12/13/90

FIGURE 29 GROUNDWATER FLOW DIRECTIONS - DEEPZONE, HIGH TIDE - 12/11/90

FIGURE 30 GROUNDWATER FLOW DIRECTIONS - DEEPZONE, LOW TIDE - 12/13/90

FIGURE 31 GROUNDWATER SEEPAGE SAMPLELOCATION PLAN

FIGURE 32 AREAS OF DISCHARGE/RECHARGE, HIGHTIDE (12/11/90), COLUMBIA AND SHALLOWZONES VERSUS INTERMEDIATE ZONE

FIGURE 33 AREAS OF DISCHARGE/RECHARGE, LOWTIDE (12/13/90), COLUMBIA AND SHALLOWZONES VERSUS INTERMEDIATE ZONE

FIGURE 34 AREAS OF DISCHARGE/RECHARGE, HIGHTIDE (12/11/90), INTERMEDIATE ZONEVERSUS DEEP ZONE

FIGURE 35 AREAS OF DISCHARGE/RECHARGE, LOWTIDE (12/13/90), INTERMEDIATE ZONEVERSUS DEEP ZONE

FIGURE 36 HISTORIC WATER SUPPLY WELLLOCATION PLAN

Vlll




FIGURE 37 BOUNDARY OF SOIL THAT EXCEEDSBACKGROUND RANGES

FIGURE 38 BOUNDARY OF GROUNDWATERTHAT EXCEEDS MCLs

FIGURE 39 PHASE III - MAXIMUM BARIUM, CIBA-GEIGYPLANT AREA SOILS

FIGURE 40 PHASE III - MAXIMUM ZINC, CIBA-GEIGYPLANT AREA SOILS

FIGURE 41 PHASE HI - MAXIMUM CADMIUM, CIBA-GEIGYPLANT AREA SOILS

FIGURE 42 PHASE III - MAXIMUM ARSENIC, CIBA-GEIGYPLANT AREA SOILS

FIGURE 43 PHASE III - MAXIMUM LEAD, CIBA-GEIGYPLANT AREA SOILS

FIGURE 44 PHASE III - MAXIMUM ANTIMONY, SILVER,NICKEL, CIBA-GEIGY PLANT AREA SOILS

FIGURE 45 PHASE III - MAXIMUM MERCURY,CIBA-GEIGY PLANT AREA SOILS

FIGURE 46 PHASE III - MAXIMUM VOLATILES,CIBA-GEIGY PLANT AREA SOILS

FIGURE 47 PHASE HI MAXIMUM COPPER AND SELENIUMCIBA-GEIGY PLANT AREA SOILS

IX

AR3|l»Ht3




FIGURE 48 MAXIMUM BARIUM, HOLLY RUN PLANT,NORTH DISPOSAL SITE, SOUTH DISPOSALSITE AREA SOILS

FIGURE 49 MAXIMUM ZINC, HOLLY RUN PLANT,NORTH DISPOSAL SITE, SOUTH DISPOSALSITE AREA SOILS

FIGURE 50 MAXIMUM CADMIUM, HOLLY RUN PLANT,NORTH DISPOSAL SITE, SOUTH DISPOSALSITE AREA SOILS

FIGURE 51 MAXIMUM ARSENIC, HOLLY RUN PLANT,NORTH DISPOSAL SITE, SOUTH DISPOSALSITE AREA SOILS

FIGURE 52 MAXIMUM LEAD, HOLLY RUN PLANT,NORTH DISPOSAL SITE, SOUTH DISPOSALSITE AREA SOILS

FIGURE 53 MAXIMUM NICKEL, HOLLY RUN PLANT,NORTH DISPOSAL SITE, SOUTH DISPOSALSITE AREA SOILS

FIGURE 54 MAXIMUM TETRACHLOROETHENE,HOLLY RUN PLANT, NORTH DISPOSAL SITE,SOUTH DISPOSAL SITE AREA SOILS

FIGURE 55 MAXIMUM TRICHLOROETHENE,HOLLY RUN PLANT, NORTH DISPOSAL SITE,SOUTH DISPOSAL SITE AREA SOILS

FIGURE 56 MAXIMUM SILVER AND VANADIUMHOLLY RUN PLANT, NORTH DISPOSAL SITE,SOUTH DISPOSAL SITE AREA SOILS




FIGURE 56A MAXIMUM ANTIMONY AND MERCURYHOLLY RUN PLANT, NORTH DISPOSAL SITE,SOUTH DISPOSAL SITE AREA SOILS

FIGURE 57 MAXIMUM COPPER AND SELENIUMHOLLY RUN PLANT, NORTH DISPOSAL SITE,SOUTH DISPOSAL SITE AREA SOILS

FIGURE 58 BALLFIELD, MAXIMUM ARSENIC/BARIUMCONCENTRATIONS

FIGURE 59 BALLFIELD, MAXIMUM CADMIUM/LEADCONCENTRATIONS

FIGURE 60 BALLFIELD, MAXIMUM ZINC CONCENTRATIONS

FIGURE 61 BALLFIELD, MAXIMUM ANTIMONY AND MERCURYCONCENTRATIONS

FIGURE 62 BALLFIELD, MAXIMUM SILVER AND VANADIUMCONCENTRATIONS

FIGURE 63 BALLFIELD, MAXIMUM COPPER AND SELENIUMCONCENTRATIONS

FIGURE 64 LEAD HAZARDS SURFACE SOILS

FIGURE 65 NORTH DISPOSAL SITE BOUNDARYREDELINEATION

FIGURE 66 WETLAND SURFACE WATER AND GROUNDWATERSEEP SAMPLING STATIONS, METALS EXCEEDINGCRITERIA AND MAXIMUM CONCENTRATIONS

XI




FIGURE 67 WETLAND SEDIMENT SAMPLING STATIONS,METALS EXCEEDING GUIDELINES, MAXIMUMCONCENTRATION AND ENRICHMENT FACTORS

FIGURE 68 CHRISTINA RIVER SEDIMENTS SAMPLING STATIONSMETALS EXCEEDING GUIDELINES, MAXIMUMCONCENTRATIONS AND ENRICHMENT FACTORS

FIGURE 69 DISTRIBUTION OF SEDIMENT ENRICHMENTFACTORS FOR METALS IN THE CHRISTINA RIVER

FIGURE 70 VINYL CHLORIDE AND CARBON TETRACHLORIDECONCENTRATIONS GROUNDWATER SEEPS ANDSHALLOW WELLS

FIGURE 71 VINYL CHLORIDE AND CARBON TETRACHLORIDECONCENTRATIONS FILL/OTHER QUATERNARYWELLS

FIGURE 72 VINYL CHLORIDE AND CARBON TETRACHLORIDECONCENTRATOR OLUMBIA FORMATION WELLS

FIGURE 73 TNYL CHLORIDE D CARBON TETRACHLORHDECONCENTRATIONS SHALLOW ZONE WELLS

FIGURE 74 VINYL CHLORIDE AND CARBON TETRACHLORIDECONCENTRATIONS INTERMEDIATE ZONE WELLS

FIGURE 75 VINYL- CHLORIDE AND CARBON TETRACHLORIDECONCENTRATIONS DEEP ZONE WELLS

FIGURE 76 TOTAL MANGANESE CONCENTRATIONSFILL/OTHER QUATERNARY WELLS

XII




FIGURE 77 TOTAL MANGANESE CONCENTRATIONSCOLUMBIA FORMATION WELLS

FIGURE 78 TOTAL MANGANESE CONCENTRATIONSSHALLOW ZONE WELLS

FIGURE 79 TOTAL MANGANESE CONCENTRATIONSINTERMEDIATE ZONE WELLS

FIGURE 80 TOTAL MANGANESE CONCENTRATIONSDEEP ZONE WELLS

Xlll

AR3UU7



VOLUME 2

LIST OF APPENDICES

APPENDIX A RESPONSE LETTER TO EPA REGARDING EPACOMMENTS ON PHASE HI RI DSR

APPENDIX B CIBA-GEIGY SEEPAGE

APPENDIX C LETTER FROM DELAWARE DOT TO DUPONTREGARDING STATE-OWNED LANDS IN AREAOF DUPONT-NEWPORT SITE

APPENDIX D EVALUATION OF VERTICAL GROUNDWATERMOVEMENT

APPENDIX E COBALT DETECTION SUMMARY TABLES

APPEND! *r GROUNDWATER CONSTITUENTS CONCENTRATIONCONTOUR MAPS

APPENDIX G RESIDENTIAL WELL DATA

APPENDIX H TIME VERSUS CONCENTRATION PLOTS

APPENDIX I LOADINGS OF CONSTITUENTS OF INTERESTTO THE CHRISTINA RIVER AND TO THESOUTHERN WETLANDS

APPENDIX J ANALYTICAL RESULTS OF 009 OUTFALLSAMPLING

xiv


EXECUTIVE SUMMARY

Activities associated with the Remedial Investigation/Feasibility Study (RI/FS) program atthe Du Pont-Newport Superfund Site (Site) started during the summer of 1987. This reportis intended to summarize all phases of the RI conducted at the Du Pont-Newport Site inaccordance with the July 22, 1988 Administrative Consent Order (ACO) executed by theUnited States Environmental Protection Agency (EPA) and E.I. du Pont de Nemours andCompany, Inc. (Du Pont). Although all of the work performed during the RI is summarizedin this report, only the results of the studies that were used in making the salient conclusionspresented in this report are focused upon. All other data and evaluations in the RI areincluded by reference.

This document, along with the referenced documents previously submitted to the EPA,satisfies the objectives of the RI Report required by the ACO, the ComprehensiveEnvironmental Response, Compensation, and Liability Act (CERCLA) and the SuperfundAmendments and Reauthorization Act (SARA). The quantification of potential risk topublic health and the environment are addressed in detail in the two-volume Final RiskAssessment, previously submitted to the EPA However, the findings of this assessment aresummarized within this report.

The Du Pont-Newport Site study area includes: an operations area (consisting of the DuPont - Holly Run Plant area and the CIBA-GEIGY Newport Plant area); two inactivelandfills (designated as the North and South Disposal sites); the associated wetlands; theassociated segment of the Christina River; the potentially impacted groundwater; and asmall recreational area (Ballpark) adjacent to and directly northwest of the Site.

In accordance with the ACO, the Site boundary has been defined on the basis of analyticaldata from the soils and groundwater media compared to background soils chemistry andMaximum Contaminant Levels for groundwater. There are no standards for determiningenvironmental impact to sediments. However, on the basis of measurable ecologicalendpoints, for which some additional data collection may be needed during the Remedial

RI Rpt/ExecSumm/88C20764W/DPN4 ES-1 5-28-92


Design phase of the Site program there is some apparent environmental impact. All of theenvironmentally impacted or potentially impacted areas defined by the soils andgroundwater media are located within the Site boundaries. No change in the Site boundaryis anticipated in response to any additional measurable ecological endpoints data collection.

The RI was performed in three basic phases. The first two phases of the RI were directedtoward characterizing the contribution of the North Disposal site and the South Disposalsite to the concentrations of Site-related constituents in the soil, groundwater, and wetlandsat and adjacent to the Site. The third phase of the RI was directed primarily at the historicoperations area as well as the perimeter of the Site as a whole. Figures 2 and 7 of thisreport present the boring locations and the monitoring well locations, respectively, for eachphase of the RI. These figures also show the locations of the North and South Disposalsites, as well as, the Du Pont. Holly Run Plant and the CIBA-GEIGY Newport Plant areas.

To meet the goals set forth in the ACO, an extensive and phased field program wasimplemented. This field program included: the installation of monitoring wells intowater-bearing zones across the CIBA-GEIGY and Holly Run Plant areas, in and adjto the North and South Disposal sites, and around the periphery of the Site; the collectionof samples from soil borings performed across these same areas; the collection of fiverounds of groundwater samples from monitoring wells at the Site; the collection ofgroundwater samples from privately owned wells along Old Airport Road southwest of theSite; the collection of groundwater from 12 seepage points identified along the north bankof the Christina River; the collection of soil samples from 12 locations in the Du Pont-owned Ballpark to the north of the Site; a number of surface surveys which included soilgas, geophysical, and radiometric investigations; and multiple wetlands investigations.

Based upon the data collected during the three phases of the RI and the subsequentevaluations, the following conclusions were drawn:

• The stratigraphic sequence of unconsolidated material at the Site includes fillmaterial, natural Quaternary deposits (other than Columbia Formationdeposits), Columbia Formation deposits, and Potomac Formation deposits.

RI Rpt/ExecSumm/88C207<>4W/DPN4 ES-2 S

AR3U150


The Potomac Formation is underlain by highly weathered crystalline basementcomplex of igneous/metamorphic bedrock.

Four main water-bearing zones were identified at the Site. The generalgroundwater flow pattern in much of the Fill/Other Quaternary zone andColumbia Formation zone is toward the Christina River. Groundwater flowin the intermediate and deep groundwater zones (Potomac Formation) isgenerally to the south and southeast. The Christina River tidal stagesprimarily affect groundwater elevations in the semi-confined intermediate anddeep groundwater zones, rather than the shallow, unconfined zones. Arelatively small amount of groundwater from the Fill/Other Quaternary andthe Columbia Formation groundwater zones adjacent to the Christina Riverdischarges to the river and the wetlands.

• Target parameters for the Site, developed upon Phase I data and retained forthe duration of the RI, are barium, ziiic j rtfcpum, tetrachloroethene, andtrichloroethene. These parameters/<app ar/TO have sources in the areasassociated with historic operations anxTwastes disposal at the Site.

• The Site target parameters are present in all four water-bearing zones at theSite. Barium and tetrachloroethene/trichloroethene are present at the highestconcentrations in the two shallowest water-bearing units. Zinc and cadmiumare present at the highest concentrations in the intermediate water-bearingzone.

• Probable mechanisms for the movement of target parameters and otherchemical constituents from the source areas to the intermediate and deepwater-bearing zones are: a downward vertical gradient between the ColumbiaFormation zone and the intermediate zone in the some areas of the historicoperations; and historic pumping of plant water supply wells to the west of—and in the historic operations area. The former pumpage of two of those >water supply wells (WW-13 and WW-11) probably also provided

RI Rpt/ExecSumm/88C2076-4W/DPN4 ES-3 ' 5-28-92

AR3U15I


mechanism for transport to the area west of the historic operations area.Natural groundwater flow gradients also provide both a historic and currentmechanism for transport of chemical constituents.

Analytical data for groundwater sampled from the residential wells along OldAirport Road shows that the operations at the Site have not impacted thesewells. However, there have been constituents of concern detected just abovemaximum contaminant level values in groundwater samples collected frommonitoring wells located at the southern side of the Site along Old AirportRoad, east of the residences.

Trends of increasing or decreasing concentrations of target parameters havebeen identified in some of the older monitoring wells at the Site (pre-1987).These trends may be an indication of chemical constituent transport. If therecurrently is any movement, it appears to be slow, especially for the metals.This may be attributable, in part, to attenuation of the metals, inby the soils in the water-bearing zones.

• The dominant metals in the soils at the Site that exceed background soilchemistry ranges were barium, zinc, cadmium, and lead. These four metalswere found widespread in the soils across much of the Site. Arsenic, copper,mercury, silver, antimony, selenium, and vanadium also show concentrationsabove background soil chemistry ranges, but these exceedances occurred inlimited areas primarily in the central portion of the historic operations areaand within the boundaries of the North and South Disposal sites. The organicparameters found in the soils at the Site included tetrachloroethene,trichloroethene, polynuclear aromatic hydrocarbons, and semi-volatileorganics. The highest concentrations of polynuclear aromatic hydrocarbonsin the soils (all less than 6 mg/kg) occur adjacent to the power plant buildingswhere coal was used as fuel. Due to the low concentrations of polynucleararomatic hydrocarbons compounds, and to the virtual immobility of thepolynuclear aromatic hydrocarbon compounds, these constituents are not

RI Rpt/ExecSumm/88C2076-4W/DPN4 ES-4

AR3UI52


considered to be of concern at the Site. These organic parameters areprimarily found in the historic operations area of the Site. The presence ofthese inorganic and organic parameters is apparently associated with historicoperations at the Site.

• The nature and horizontal and vertical extent of the chemical constituents inthe soils and groundwater at the Site have been sufficiently characterized anddelineated. The locations of the probable sources for these constituents inthese two media have also been adequately identified during the RI and arediscussed in this report.

• Atmospheric transport of Site-related chemical constituents was addressed bysampling soils in the Du Font-owned Ballpark adjacent to the Site. This areawas selected because it is one of the few areas of Newport north of the Siteconsidered to be undisturbed, and it is located downwind from the Site duringportions of the year. A limited area of the shallow soils sampled from theBallpark show elevated concentrations of barium, zinc, and cadmium. Thesource of these metals is believed to be fill material historically transportedmanually from the Newport Plant to manicure the infield of the ballfield orby tracking to the former parking lot, rather than associated with air transport.Because soil samples that were collected from undisturbed locations at theBallpark showed metal concentrations within naturally-occurring backgroundranges, historical aerial transport of metals from the Site is not considered anissue of concern.

• The Human Health Evaluation (HHE) evaluated carcinogenic and non-carcinogenic risks to humans at the Site. For carcinogenic risks, allcumulative excess lifetime cancer risks associated with the average case forcurrent land use at the Site were estimated to be below 10"6. For theReasonable Maximum Exposure assumptions, which are v *$\ conservativeand, thus, may grfc ly over-estimate risks, all estimated potential excesslifetime cumulative carcinogenic risks were at or below 1.4 x 10"5. These

RI Rpt/ExecSumm/88C2076-4W/DPN4 ES-5 5-28-92

flR3|(*lS3


values are well within the 104 to 106 acceptable risk range in the National Oiland Hazardous Substances Contingency Plan (NCP).

• Cumulative carcinogenic risks were below 10"6 for hypothetical futureconstruction scenarios under average conditions, and at or below 1.1 x 10"5under Reasonable Maximum Exposure assumptions. These results suggestthat no unacceptable cancer risk is associated with potential constructionactivities at the Site.

• Potential carcinogenic risk for the hypothetical future ingestion ofgroundwater are below or within the acceptable risk range at 5.7 x 10"7(Potomac Formation) and 2.1 x 10~5 (Columbia Formation) for the averagecase. Risk based on Reasonable Maximum Exposure assumptions are withinthe acceptable range for ingestion of Potomac Formation groundwater (4.6 x106), but are above the 104 level for groundwater ingestion from theColumbia Formation (3.0 x 104). These estimates are consideredconservative due to the conservative approach used in estimatingexposure concentrations for groundwater and EPA's directive to assumeingestion would occur from a hypothetical well located in the existingNecastro auto salvage yard adjacent to existing monitoring well MW-19.

• Overall for the Du Pont-Newport Site, all estimated cumulative excess lifetimecarcinogenic risks were below or well within the acceptable risk range of 104to 1C6 in the NCP for both current and future land use scenarios with theexception of the hypothetical scenario for the ingestion of groundwater fromthe Columbia Formation.

• For non-carcinogenic hazards other than lead, aj l cumulative chronic hazardindices under average and Reasonable Maximum Exposure case conditionswere below the acceptable level of 1.0 for current land use, suggesting thereare no current unacceptable non-carcinogenic hazards. For potential futureconstruction activities, total subchronic non-carcinogenic hazard indices are

RI Rpt/ExwSumm/88C2076-4W/DPN4 ES-6


below 1.0 for average conditions, but slightly above 1.0 for ReasonableMaximum Exposure assumptions (hazard index = 2.5 for subchronicexposure) at the CIBA-GEIGY Plant area. This finding was associatedprimarily with incidental ingestion of soil particulates containing antimony,arsenic, barium, cadmium, and cobalt. The procedures instituted by CIBA-GEIGY to control worker exposure to potentially contaminated subsurfacesoils during soil excavation and other intrusive activities should reduce futureworker exposure below the values estimated in the HHE.

• Cumulative hazard indices for the hypothetical ingestion of ColumbiaFormation groundwater from a hypothetical future well adjacent to MW-19A(located in the existing Necastro auto salvage yard) exceeded one for bothaverage and Reasonable Maximum Exposure cases. Cobalt was the majorcontributor to these calculated hazards. The cumulative hazard index forhypothetical residential ingestion of groundwater from the Potomac Formationwas also above 1.0 for Reasonable Maximum Exposure assumptions. Cobaltwas also a primary contributor to this risk. The potential risk associated withcobalt is considered(greajly over-estimated due to the directive from EPARegion HI to use aYvery conservative Reference Dose for cobalt and to usethe assumption that ingestion of on-Site groundwater occurs. Based on thedistribution patterns of cobalt at the Site compared to the distribution ofother Site-related metals of concern, the cobalt may be naturally occurring.Removal of the cobalt from the risk calculations would reduce the non-carcinogenic hazard index for the Potomac Formation ingestion scenario toless than 1.0. Removal of cobalt would also significantly reduce the hazardindex for the Columbia Formation ingestion scenarios. The hazard indicesare also considered conservative because attenuation and retardation ofchemicals during transport were not considered in modeling groundwaterconcentrations. Furthermore, the future installation of public water suppljwells or additional residential wells along Old Airport Road is consiunlikely due to the present land use which is dominated by automobilesalvage yards, the relatively low yield of the Potomac Formation water-bearing

RI Rpt/ExecSumm/88C20764W/DPN4 ES-7 5-28-92

AR3UI55


units in the area, the likely implementation of a groundwater managementzone by DNREC, and the high probability of Du Pont providing public watersupply pipelines along Old Airport Road.

An action level of 1000 ppm for lead in all surface soils was proposed byDu Pont, based upon previous EPA Records of Decision, by letter to the EPARegion III dated July 10,1991. Subsequent discussions between Du Pont andthe EPA Region III resulted in an agreement for using an action level of 500ppm for lead in surface soils in areas where exposure to children oradolescents is considered likely. Likewise, Du Pont and the EPA Region UIagreed to use an action level of 1000 ppm for lead in surface soils in areaswhere only industrial exposure is anticipated. Hazard quotients werecalculated for lead in soils and groundwater based on EPA directionconcerning the action levels for lead in soils and the drinking water. Hazardquotients for lead above ten were estimated for exposure to CIBA-GEIGYPlant soils and ingestion of Columbia Formation groundwater.quotients for lead above one were also estimated for exposure toDisposal site and South Disposal site soils and ingestion of PotomacFormation groundwater. Methods for eliminating or controlling exposure tolead in surface soils and groundwater above the action level will be evaluatedin the Feasibility Study for the Site.

Monitoring of fish tissue for lead content, and subsequent modeling of leadexposure for humans eating the fish, indicated that no significant risk wasassociated with lead from ingestion of fish caught in the Christina River.

Based on the Environmental Evaluation (EE), the central portion of theNorth Disposal site drainageway from the vicinity of Station AS07 to thevicinity of Station AS09 has been impacted by Site-related constituents.Surficial sediment levels of all constituents are much greater than EPAThreshold Value Guidelines. Stations AS07 and AS08 (central portion ofnorthern drainageway) had some of the highest geochemical enrichment

RI Rpt/ExecSumm/88C20764W/DPN4 ES-8

AR3UI56


factors among all stations sampled. Impoverished benthic communities, andsignificantly poor survival in toxicity testing as compared to field referencestations, also suggest that an impact exists in the central portion of thedrainageway. Based on the data, constituent concentrations and impactsdecrease moving downstream from Station AS07.

Ecological endpoints (i.e., benthic density and richness, and toxicity testresults) used to characterize the South Disposal site wetlands providecontradictory information. Benthic community data suggest impacts; toxicitytest survival using the minnow, water flea and midge larvae in Station AS03surface water or sediment was not significantly different from the level ofsurvival at the field reference location or in the negative lab control.Ecological impact to benthic macroinvertebrates appears to be minimal sincesediment chemistry improves markedly with distance from the berm, inferringthat the extent of ecological impact is limited to areas adjacent to the berm,inferring that the extent of ecological impact is limited to areas adjacent tothe berm. Additional data collection during the Remedial Design phase willbe needed to refine the area of impact.

Of the river stations sampled, Stations RS05, RS06, RS07, RS11, and RS12show sediment enrichment for at least some Site-related constituents. Ofthese stations, only Stations RS11, RS12 and sometimes RS07 had measurableimpairment in terms of benthic density and richness and toxicity testing resultsrelative to background conditions for these same endpoints. The extent to[hich data from Stations RS11 and RS12 characterize the northern portion

e Christina River in the Site vicinity is not known. For the remainder ofe Site study area, no impact to aquatic receptors -due to Site-related

constituents or activities can be concluded, based on the weight of evidenceof biological data collected at specific stations.

The Hazard Index Methodology was used in the EE as a screening tool toevaluate possible risk to terrestrial receptors This method does not provic

RI Rpt/ExecSumm/88C207fr4W/DPN4 ES-9 5-28-92

AR3UI57


an accurate analysis of risk. Potential impacts on wildlife from ingesting food,sediment, soil, and water containing a variety of elevated metalsconcentrations cannot be readily predicted using available evaluationtechnology. Owing to the number of assumptions which are inherent in theHazard Index Methodology, this approach and the results were used only asa screening tool to assess the potential for terrestrial risk. Based on theterrestrial/wetland analysis portion of this EE, several Site-related stationshave been identified that may potentially pose some minor risk to terrestrial•"ildlife as represented by the deer mouse, muskrat, and great blue heron.However, none of the measured concentrations of ecological constituents o;ISmeern are considered to pose significant risk or the potential fo/ acute toxic,reaction to these three receptors.

Chronic exposure for terrestrial receptors to the elevated zinc, barium, lead,and chromium concentrations in the North Disposal site and North Disposalsite drainageway may result in some negligible or minor impacts basedhazard indices computed. However, elevated levels of these constituentsthe North Disposal site occur only at limited areas which are characterized bysurface soils chemistry data from landfill ore material (SGS-6). It is estimatedthat these areas, which are unvegetated, represent less than 10 percent of thesurface area of the North Disposal site. Since these areas are unvegetated,they are less attractive to receptors (i.e., deer mouse), hence reducing thepotential exposure.

Given the overall low Hazard Index results (highest Hazard Index value =1.7) for each of the areas evaluated, it appears unlikely that significantimpacts to the deer mouse, muskrat, or great blue heron can be expected tooccur as a result of exposure to levels of constituents found at the Site. Anyadverse impacts to terrestrial animals that may be expected to occur at thisSite, could be classified as minor, in that only a few localized individuals arelikely to be affected.

RI Rpt/ExccSumm/88C2076-4W/DPN4 ES-10 5-

AR3IM58

zSr


The South Disposal site wetlands vegetation appears to be acting as a "sink"or "filter" for sediment which acts to sequester metals, limiting their transportto the Christina River and downstream environments. The available data alsosuggest that the Site-related constituents may not be bioavailable underexisting conditions in this area of the Site.

The ecological evaluation of the Christina River has taken into considerationthe overall condition of the entire watershed which has been, and continuesto be impacted from non-Site related sources. Sediment chemistry andtoxicity test data collected at some of the river stations in the vicinity of theSite were similar to background conditions measured at reference StationRS15 located approximately 3.5 miles upstream from the Site. Likewise,discharges to the Christina River in the Site vicinity include: two City ofNewport stormwater pipes which have industrial input from off-site; andCIBA-GEIGY permitted (NPDES) outfalls.

RI Rpt/ExecSumm/88C2076-4W/DPN4 ES-11 5-28-92

AR3UI59


1.0INTRODUCTION

The Du Pont-Newport Superfund Site (Site) is located to the south of the Town of Newport,Delaware, and bisected by the Christina River (see Figure 1). The study area of the Siteconsists of: an operations area (consisting of the CIBA-GEIGY Newport Plant area and theDu Pont Holly Run Plant area); two inactive landfills labeled the North Disposal site andthe South Disposal site (see Figure 2); the associated wetlands; the associated segment ofthe Christina River; the potentially impacted groundwater; and a small recreational area(Ballpark) located immediately northwest of the operations area.

1.1 PURPOSE OF THE REMEDIAL INVESTIGATION REPORT

Activities associated with the Remedial Investigation/Feasibility Study (RI/FS) program atthe Site started during the summer of 1987. This report is intended to summarize all phasesof the RI conducted at the Du Pont-Newport Site in accordance with the July 22, 1988Administrative Consent Order (ACO) executed by the United States EnvironmentalProtection Agency (EPA) and E.I. du Pont de Nemours and Company, Inc. (Du Pont).Although three phases of investigation were performed at the Site, this report will generallyaddress the RI as one complete investigation. The basic objectives of this RI, as related tothe ACO and in accordance with the Comprehensive Environmental Responsibility,Compensation, and Liability Act (CERCLA), and Superfund Amendment andReauthorization Act (SARA) regulations and guidance documents, are to:

• Determine if chemical constituents from plant operations have migrated intogroundwater or surface water on-Site or off-Site and, if so, determine theirconcentrations and vertical/horizontal extent

.• Identify and characterize the extent of Site-related chemical constituents inthe soil and sediment present at the Site

RI Rpt/Sectl-3/88C2076-4W/DPN4 1-1 5-28-92

AR3IM60


• Determine if atmospheric transport of chemical constituents related to plantoperations has occurred off-Site and, if any has, determine its concentrationand extent

• Define the physical features of the Site that could affect potential chemicalmigration, containment, and remediation

• Quantify the potential risk to public health and evaluate any impact orpotential hazard to the environment

• Gather information necessary to support the FS

• Define the boundaries of the Site based on the RI Data.

1.1.1 Initial Investigations (1975 to 1986)

Previous to the RI, hydrologic groundwater quality investigations were conducted byPont at the Site under the approval of the State of Delaware Division of Natural Resourcesand Environmental Control (DNREC). These investigations were performed as part of theNorth Disposal site closure. On the basis of monitoring well and boring descriptions, as wellas the groundwater level monitoring program conducted by Du Pont, an initial conceptualmodel of groundwater flow was developed by Du Pont hydrogeologists. These hydrogeologicdeductions provided the basis for inferring the fate of chemicals introduced into thegroundwater system and developing the plans for later hydrogeologic investigations.

In addition to the previously existing supply wells WW-11 and WW-13, 16 test borings and13 monitoring wells were installed by Du Pont from 1975 to 1986 to evaluate the geologicand hydrogeologic conditions in the vicinity of the Site. Nine of the original 13 monitoringwells are still utilized to monitor groundwater quality and water levels.

RI Rpt/Sectl-3/88C2076-4W/DPN4 1-2 5-:

AR3U16I

;-!Hz

woodward-ClydeConsultants

1.1.2 Remedial Investigation Phases

Du Font's hydrogeologic investigations from 1975 to 1986 were focused primarily on theNorth Disposal site. In 1986, the North Disposal site was the subject of the HazardousRanking System (HRS) evaluation made by the EPA Because certain waste products werealso disposed in the South Disposal site, it was apparent that a RI of the North Disposal sitealone would not totally satisfy Du Font's or EPA's concerns regarding potential harm to thepublic and/or environment from chemical constituents associated with disposal of thesewastes. Consequently, Du Pont directed Woodward-Clyde Consultants (WCC) to conducta series of RI tasks during June, July and August of 1987 toward acquiring additionalinformation in order to determine whether the Site should be listed on the EPA's NationalPriorities List (NPL). This work, completed under a proposed RI/FS Work Plan dated July20, 1987, constituted Phase I of the RI.

At the request of the EPA, Du Pont proposed a second phase of the RI (Phase II) whichwas outlined in the July 1988 RI/FS (Phase II) Work Plan for the Site. The Phase II RIwas completed during the second half of 1988. Early in 1989 the Site was formally listedon the EPA's NPL. Subsequently, the EPA required that an additional phase of the RIshould be performed in general accordance with the guidelines provided in the "EPAGuidance for Conducting Remedial Investigations and Feasibility Studies under CERCLA,October 1988," which also reflect the emphasis and provisions of SARA The workcomponents for this final Phase III RI was proposed by Du Pont to further satisfy therequests of the EPA concerning the Site issued in a letter dated March 8, 1990. The PhaseHI RI was completed during the period April 1990 through April 1991, and the results werereported to the EPA in the May 17, 1991 Phase III RI Data Sufficiency Report.

1.2 PREVIOUS REPORTS

As indicated above, several Work Plans and reports were issued to the EPA which outlinedthe scope of each phase of the RI and reported the results of these investigations. Thesereports and plans, listed and described below, will be referenced throughout the RI Reportusing the following abbreviations:


HR3UI62


Date Issued____Report Title____ Abbreviation to EPA

Proposed RI/FS Work Plan (Phase I) PWP July 20, 1987

Work Plan (Phase II), Remedial WP July 28, 1988Investigation/Feasibility Study,Du Pont-Newport Site, Volumes I, II, III

Quality Assurance/Quality Control QA/QC PI November 3, 1988Audit, Phase I - RI Data,Du Pont-Newport Site

Quality Assurance/Quality Control QA/QC PII March 8, 1989Audit, Phase II - RI Data,Du Pont-Newport Site

Quality Assurance/Quality Control QA/QC WI January 1989Audit, Wetlands Investigation,Du Pont-Newport Site(Appendix C of WI)

Wetlands Investigation (Phase II), WI March 23, 1989Du Pont-Newport Site

Data Sufficiency Memorandum-Remedial DSM April 27, 1989Investigation, Phase H,Du Pont-Newport Site

Data Sufficiency Supplement, Remedial DSS November 1989Investigation, Phase H,Du Pont-Newport Site

Phase m Wetlands Investigation, WI HI January 1990Technical Data Summary Report,Du Pont-Newport Site

Quality Assurance/Quality Control QA/QC WI HI January 1990Audit, Phase HI Wetlands InvestigationDu Pont-Newport Site(Appendix A of WI III)

RI Rpt/Sectl-3/88C2076-4W/DPN4 1-4 •


Date Issued____Report Title____ Abbreviation to EPA

Final Phase III Remedial Investigation WP in February 5, 1991Work Plan

Phase III Remedial Investigation, DSR III May 17, 1991Data Sufficiency Report,Du Pont-Newport Site

Quality Assurance/Quality Control QA/QC DSR III May, 9, 1991Audit Report, Phase III RemedialInvestigation, Du Pont-Newport Site(Appendix F of DSR III)

Draft Risk Assessment RA(D) July 30, 1991 (EE)Du Pont-Newport Site October 14, 1991 (HHE)

Draft Remedial Investigation Report November 1, 1991Du Pont-Newport Site

Final Risk Assessment RA March 18, 1992 (HHE)Du Pont-Newport Site April 29, 1992 (EE)

The Proposed RI/FS Work Plan dated July 20, 1987 outlined the initial phase (Phase I) ofthe investigation designed to collect data to determine the need for a complete RI/FSprogram. If the Phase I data suggested that further study was needed to determine whetherthere was any potential threat to human health and/or the environment, then a secondphase remedial investigation would be developed. The work outlined in the July 20, 1987Work Plan was completed during the period of June through August 1987.

The Work Plan, Remedial Investigation/Feasibility Study, dated July 28, 1988 served thedual purposes of reporting the results of the Phase I Remedial Investigation and outlininga Phase H Remedial Investigation, an Endangerment Assessment, and a Feasibility Study.The Work Plan was developed in order to address the objectives of the RI/FS containedin the Consent Order.

RI Rpt/Sectl-3/88C20764W/DPN4 1-5 5-28-92

HR3W6U


The Wetlands Investigation Report dated March 23, 1989 summarizes the results of aninvestigation of the sediment and surface water chemistry at wetland areas associated withthe Du Pont-Newport Site conducted as part of the Phase U RI. Field work for the effortwas conducted in September 1988.

The Data Sufficiency Memorandum, Remedial Investigation-Phase II, dated April 27, 1989,served to document the results of the Phase II RI and evaluate the sufficiency of the RI datain accordance with Section 3.2 of the WP. The data from both Phase I and Phase II wereevaluated to determine their adequacy to support the Endangerment Assessment and theFeasibility Study.

The Phase III Wetlands Investigation, Technical.Data Summary Report, dated January 1990,summarizes the results of additional data collection conducted to assess the potentialbiological impacts associated with the Du Pont-Newport Site, and to clarify some of the datacollected in the Phase II study. The study included laboratory analyses of sediments todetermine physical characteristics, levels of radium-228, and concentrations ofAnalyte List (TAL) metals, to assess relative toxicity of sediments to aquatic biota,characterize resident benthic communities. Other parts of the Phase HI WetlandsInvestigation were the verification of wetlands boundaries adjacent to the North Disposalsite, the collection of fish for tissue analyses, and the collection and analysis of field filteredand non-filtered surface water samples.

The Data Sufficiency Supplement dated November 1989 was prepared and issued by WCCin response to the EPA review comments to the Data Sufficiency Memorandum dated April27, 1989, and the June 29, 1989 meeting between Du Pont and the EPA The additionalwork included a review of all available historical maps, files, and photographs to constructa summary of historical processes and materials handling at the Newport Plant. Alsoinvestigated were the thorium-related operations, for which historical information wasreviewed to confirm the waste burial location. Field investigations were conducted toprovide additional radiometric data in the vicinity of the North Disposal site.

RI Rpt/Sectl-3/88C2076-4W/DPN4 1-6

AR3U165


The Final Phase III RI Work Plan, February 5, 1991, was developed in response to requestsby the EPA in letters dated January 17 and March 8, 1990. The Phase III RI Work Planoutlined further investigations at the CIBA-GEIGY Newport Plant area, the Du Pont HollyRun Plant area, the South Disposal site, and involved all of the potentially impactedgroundwater, the associated wetlands, and the associated segment of the Christina River.The Final Phase III Work Plan was issued following completion of the majority of the PhaseIII RI field work. However, all aspects of the field work were conducted under the auspicesof the EPA, and in accordance with written and verbal agreements reached between theEPA and Du Pont before and during the field operations.

The Phase HI Remedial Investigation, Data Sufficiency Report presents the data collectedduring the Phase III Remedial Investigation completed during the period from April 1990to April 1991. This report also demonstrates that all RI data collection requests of the EPAto date had been satisfied and that the data were sufficient to prepare the Risk Assessment,RI Report and the Feasibility Study. The EPA issued comments regarding this report onAugust 16, 1991. WCC responded to these comments on behalf of Du Pont in a letter toEPA, dated August 23, 1991. This response letter (presented in Appendix A), inconjunction with this RI report, addresses the EPA comments on the DSR III.

The Draft Risk Assessment Report was submitted to the EPA for their review in twovolumes. Volume one contained the Human Health Evaluation (HHE) and was submittedon October 14, 1991. Volume two contained the Environmental Evaluation (EE) and wasdated July 30, 1991. The purpose of these evaluations was to quantify the potential risk topublic health and the environment. The HHE 1) examined the current levels of chemicalsat the Site, 2) portrayed potential current and future exposure scenarios to these chemicalsby human populations, and 3) estimated the carcinogenic risks and non-carcinogenic hazardsassociated with these potential exposures. The purpose of the EE was to identify specificlocations in the Site study area, if any, where the extent of apparent or potentialenvironmental impact might warrant remediation. In response to numerous EPA reviewcomments, teleconferences and workshops, the Final Risk Assessment documents weresubmitted to the EPA on March 18, 1992 (HHE) and April 29, 1992 (EE). Rather thanbeing appendices to the RI report, these documents were submitted under separate cover


UR3IU66


to the EPA. A summary of the conclusions reached based on these evaluations is presentedin Section 6.0.

1.3 SITE HISTORY

The Newport Plant (not to be equated to the Du Pont-Newport Superfund Site) is a pigmentmanufacturing plant now owned by CIBA-GEIGY, located at James and Water Streets inNewport, Delaware. The plant was originally owned and operated (from 1902 to 1929) byHenrik J. Krebs for the manufacture of Lithopone, a white inorganic pigment. In 1929, DuPont purchased the plant and continued to manufacture Lithopone along with othermaterials, including organic and inorganic pigments. The pigment manufacturing operationswere purchased by CIBA-GEIGY in 1984, while chromium dioxide magnetic recording tapeoperations were retained by Du Pont at their Holly Run Plant. The history of productionat, and the development of, the Site is summarized below. A detailed discussion of thisproduction history is presented in the DSS.

As early as 1900 there was a small Lithopone business in the area of present-day Build47 (see Figure 3). Late in the summer of 1901, Henry J. Krebs broke ground at theNewport Plant to start his Lithopone pigment business. The first major expansion of theKrebs business occurred in 1916 when Buildings 17, 19, 20, 21, 23, 24 and 30 were built tohouse the filtering, drying, storage, and powerhouse operations. By 1926 the plant wasproducing 75 tons of Lithopone per day.

Following Du Font's purchase of the Newport Plant from Krebs in 1929, a research building(Building 47) was established by Du Pont in 1932 to investigate new pigment technologies.Titanium pigments were already being developed by other manufacturers in the early 1920s.During the next 20 years, from 1932 to 1952, a product transition occurred in whichLithopone became less popular and titanium dioxide pigments became more popular in thetrade, ending with Lithopone being shut down in 1952.

The year 1948 also saw the construction of facilities (Building 100) to manufacture blue,green, and yellow copper phthalocyanine pigment (CPC). In 1958 the production of

RI Rpt/Sectl-3/88C2076-4W/DPN4 1-8

ftR3IUI&r


Quinacridone pigment (QA) was started in Building 27. The QA processes generate avariety of red shades of pigment. All three of these pigments are known by their tradename "Monastral." The production of CPC ceased in 1984, but QA is still being producedtoday by CIBA-GEIGY.

Other historical Du Pont operations at the plant included the production of: titanium metal,manufactured at the plant from approximately 1948 to 1960; thoria dispersed modifiednickel from 1961 to 1966; high purity silicon, from approximately 1942 to 1958; "Ti Pure"finishing operation, which yielded a TiOj white pigment made from TiCi, slurry receivedfrom the Edgemoor Plant; and other new pigment products such as "Afflair" flake pigments(mica coated with titanium oxide) that were manufactured at the pilot plant on ademonstration scale.

All of the plant facilities related to the above operations were sold to CIBA-GEIGY in1984. Also included in the sale were facilities used by Du Pont to produce chromiumdioxide powder from 1966 to 1984. Only QA production has been continued from the timeof the sale to the present under CIBA-GEIGY ownership.

Portions of the original Du Pont Plant were retained after the sale of the facility to CIBA-GEIGY in 1984 as the Du Pont Holly Run Plant. The retained portions includedmanufacturing and non-manufacturing buildings. Retained were manufacturing facilitiesconstructed for chromium dioxide powder production in 1978 and a chromium dioxidemagnetic tape production unit which operated from 1966 to 1983. The only constituentassociated with the Holly Run Plant manufacturing operations is chromium.

During plant operations, two portions of the Site bordering the Christina River werelandfilled as a means of waste disposal. Landfilling occurred in both the North Disposal siteand the South Disposal site (Figure 2). The North Disposal site was used for disposal ofgeneral refuse and process wastes from early 1902 until 1974. The North Disposal sitereceived a variety of material, including plant debris such as off-specification product Corian(imitation marble) counters, empty steel drums, metal alloys, liquid wastes, and pigmentmuds. A detailed listing of likely waste composition is provided in Section 1.2.1 of the WP

RI Rpt/Sectl-3/88C207fr4W/DPN4 1-9 . 5-28-92

flR3ll*!68


Report. A waste disposal inventory for the North Disposal site is also provided in Table 1.After disposal ceased in 1974, the North Disposal site was capped with approximately 2 feetof clayey material.

The South Disposal site was operated from approximately 1902 to 1953. Materialsdeposited in this landfill consisted of primarily insoluble residues of zinc and barites ores,which were pumped as a slurry through a pipeline across the Christina River. Some dikesand berms were constructed to contain the material. In 1973, the State of Delaware,Department of Highways, deposited approximately 130,000 cubic yards of additional soilfrom highway construction at this location, covering the South Disposal site with an average3 feet of variable soil. The following sections provide a history of specific operationsconducted at the Site which have been subject to the most scrutiny by the EPA andinvestigation by Du Pont.

1.3.1 Lithopone

The production of Lithopone at the Site occurred in the buildings and at the areas shon Figure 3. Undissolved residues from the Lithopone production process were primarilypumped across the Christina river to the South Disposal site. A detailed description of theproduction of Lithopone is provided in the DSS.

Zinc and barium ores were processed to produce the white Lithopone pigment, which wasa combination of zinc sulfate and barium sulfide. From the descriptions of the entireLithopone manufacturing process, the occurrence of the basic Lithopone metals, zinc andbarium, and other heavy metals commonly associated with zinc and barium ores (cadmium,nickel, lead, mercury, and arsenic), in both soils and groundwater in the operations anddisposal area is due to past Lithopone operations.

1.3.2 CPCandQA

The manufacture of the organic pigments CPC and QA began in 1948 and 1958,respectively. The CPC pigments were blue, green and yellow green color shades, while the

* . , - - - . - —

flR3U!69


QA pigments were shades of red. CPC was manufactured and handled in Buildings 100,101, 103, and 120 initially, and expanded in 1970 to include Buildings 70,200, and 220. Theproduction areas for CPC and QA are shown on Figure 4.

CPC operations at the Site were terminated in 1984 when the Newport Plant was sold toCIBA-GEIGY. All waste disposal in the North Disposal site and South Disposal siteoccurred prior to the sale of the Newport Plant to CIBA-GEIGY. As mentioned above, theQA manufacturing continues today under CIBA-GEIGY ownership in the same areas andusing the same chemical processes and materials previously used by Du Pont, with oneexception. Tetrachloroethene was a solvent historically used in the production of both CPCand QA. CIBA-GEIGY stopped using tetrachloroethene in the QA process in December1990. The presence of tetrachloroethene and trichloroethene in the soils and thegroundwater at the Site is believed to be associated with the historic production of CPC andQA. Tetrachloroethene was also used during the production of titanium in two of the samebuildings as CPC (Buildings 200 and 70), and prior to CPC production as discussed below.Wastes from these above operations, including tars from the distillation processes associatedwith QA production, were disposed of in the North Disposal site.

As described above, the tetrachloroethene, trichloroethene, and degradation products at theSite are apparently related to the production of CPC, QA, and titanium oxide.Tetrachloroethene was used up to 1984 in the production of both CPC and QA The useof tetrachloroethene in the QA process continued until December 1990. The source of thetetrachloroethene, trichloroethene and degradation products is considered to be primarilydue to historic operations. It is uncertain whether the more current operations (i.e., after1984) have contributed to the presence of tetrachloroethene, trichloroethene, anddegradation products and related organics in the soil and groundwater at the Site. If anyimpact from more recent operations has occurred, it would be relatively small. The sourceof the trichloroethene is considered to be either degradation of the tetrachloroetheneformerly used at the Site and/or the possible presence of trichloroethene as a minorconstituent of the tetrachloroethene solvent formerly utilized at the Site.

RI Rpt/Sectl-3/88C20764W/DPW 1-11 5-28-92


1.3.3 Titanium Metal

Titanium metal was produced at the Site from 1948 to the mid-1950s and, after a shortperiod of non-production, again on a smaller scale from the late 1950s to 1960. Productionstarted on the research level in Buildings 47 and 21, with small scale production units inplace at Buildings 18 and 23 by 1950. Large-scale production of titanium began in Buildings70, 200, and 201 by 1952 (see Figure 5).

The organic solvent tetrachloroethene was used in the production of titanium metal as adegreaser of the magnesium in Buildings 70, 200 and 201. Thus, the titanium process couldhave contributed to the tetrachloroethene and trichloroethene observed in soils andgroundwater samples from the central portion of the operations area. No other analyticalparameters have been identified in the soil or the groundwater at the Site which areattributable to the production of titanium products.

1.3.4 Thoria Dispersed Modified Nickel

Under the permitting authority of the federal Atomic Energy Commission (AEC), Thorium-232 was used at the Site during the period from 1961 to 1966 as part of the Du Font'sDispersion Modified Metals program to impart improved high temperature properties tometals such as nickel. Thoria Dispersed Nickel (TD Nickel) was the only material of thistype produced at the Newport Plant in pilot unit quantities (several hundred pounds perday).

Extensive studies associated with tracking the disposal of wastes from this process have beenperformed during the RI. These studies included: surface radiometric surveys; groundwater,surface water, and sediment sample collection for the analysis of Thorium-232; the collectionof soil from the North Disposal site for the analysis of Thorium-232 including field screeningof the soil with a Geiger counter; and, finally, a review of documentation regarding AEC-permitted disposal and burial locations of wastes associated with TD Nickel. Based uponthese investigations, it has been determined that TD Nickel wastes were disposed of in the

RI Rpt/Sectl-3/88C207<>4W/DPN4 1-12 5-2 K


North Disposal site in accordance with the AEC regulations. All RI d ta collection andevaluation suggest that there has been no leakage from the buried drur

The potential for future release of thorium to the environment is very low, if any. Even ifthe containers holding the TD Nickel did eventually leak, the likelihood of the migrationof radioactive materials from the burial site is very low due to the radiological propertiesof the material as well as the hydrologic and geochemical constraints. A detailed analysisof this subject is presented in the DSM.

Thus, the potential surficial or subsurface impacts from TD Nickel operations or wastedisposal are no longer an issue at this Site. More detailed discussions of TD Nickel areavailable in the following reports: WP, DSM, and the DSS.


AR3U172


2.0FIELD INVESTIGATIONS

This section provides a summary of the field investigations which were performed during thethree phases of the Remedial Investigation at the Du Pont-Newport Site. Complete datasubmittals, operational field procedures, and detailed data evaluations are provided in theindividual data reports for each phase of the RI. A summary of the salient conclusionsdrawn from the three phases of field investigations is provided in Section 6.0.

2.1 MONITORING WELL INSTALLATION

A total of 85 monitoring wells were installed at the Site during the 1975 to 1991 period,from before the RI, through all three phases of the RI. The monitoring wells were installedto monitor the quality of groundwater in the major water-bearing strata at the Site and toprovide other hydrogeologic data. A list of the monitoring wells installed and currently usedat the Du Pont-Newport Site is provided in Table 2. Figure 2 provides a location plan forthe wells installed during each phase of the RI.

Previous to the RI, 13 monitoring wells were installed at the Site during the period spanning1975 to 1981 to evaluate the hydrogeologic conditions and groundwater chemistry in theimmediate vicinity of the North Disposal site. Nine of these monitoring wells are presentlybeing utilized to monitor conditions at the Site. The other four were abandoned inaccordance with DNREC regulations over a period of years for a variety of reasons.

Twenty-seven monitoring wells were installed as part of the Phase I RI in accordance withthe PWP. The Phase I monitoring wells constructed during the summer of 1987 werescreened in the shallow, intermediate and deep water-bearing zones (see Section 3.3.4.1),primarily, at the North and South Disposal sites. The data from the Phase I monitoring wellinstallations and sampling, including the boring logs and monitoring well reports, werepreviously submitted to the EPA in the WP.

RI Rpt/Sectl-3/88C207fr4W/DPN4 2-1 5-28-92

HR3IU73


Seven monitoring wells were installed during the Phase II RI as requested by the EPA.Data collected from these wells were intended to confirm the conclusions drawn from thePhase I groundwater investigation as outlined in the WP, and to provide additionalgroundwater and soils data around the perimeter of the North Disposal site and the SouthDisposal site. The procedures used to install these wells, and the details of well constructionand sample collection are provided in the DSM, along with the complete data submittalfrom the Phase II RI.

Forty-two additional monitoring wells were installed as requested by the EPA at the Site aspart of the Phase III RI. The purpose of these wells was to better define the potentialimpact on groundwater chemistry at the periphery of the Site and to gather detailedgroundwater and soils data in the vicinity of and immediately downgradient of thecentralized areas of historic manufacturing operations. The Phase III monitoring wells wereinstalled during Summer and Fall 1990 in accordance with the procedures outlined in theWP III. The complete data submittal resulting from the Phase in monitoring wellinstallations are provided in the DSR III.

2.2 GROUNDWATER SAMPLING

Groundwater sampling was conducted at the Site during each Phase of the RI. The purposeof the sampling was to evaluate and characterize groundwater quality in the major water-bearing zones at the Site. The groundwater samples were collected from monitoring wells,groundwater seepage, and residential wells on Old Airport Road as described below.

22.1 Monitoring Wells

In August 1987, during the Phase I RI, groundwater samples were collected from 27 newlyinstalled monitoring wells and 10 of the 12 pre-existing monitoring wells. These sampleswere analyzed for Hazard Substance List (HSL) parameters and sulfate (SO4). A secondround of water samples was collected as part of Phase I during December 1987. During thissecond round of Phase I groundwater sampling, 36 on-site monitoring wells were sampledand analyzed for HSL organics, and metals and SO4. Groundwater samples collected north

€1RI Rpt/Scctl-3/88C207MW/DPN4 2-2 S-2&T


of the Christina River during August 1987 were also analyzed for gross alpha and betaradiation. The monitoring wells sampled during Phase I of the RI are listed in Table 3.Detailed procedures and results of sampling during Phase I are provided in the WP.

During Phase II of the RI, two rounds of groundwater samples were collected frommonitoring wells. The first round included the newly installed Phase II wells plus five pre-Phase II wells. The pre-Phase II wells were analyzed for total and dissolved zinc, while thePhase II wells were analyzed for Target Compound List (TCL) volatile organics and totaland dissolved metals. The second round of groundwater sampling included 35 pre-Phasen wells and the Phase II wells. The pre-Phase II wells were analyzed for total and dissolvedzinc cadmium, and barium. The Phase II wells were analyzed for TCL volatile organics, andtotal and dissolved TAL metals. A list of all monitoring wells sampled during Phase II isprovided in Table 4. Sampling procedures and results of groundwater sampling werepreviously submitted in the DSM.

In November 1990, groundwater was sampled from 84 monitoring wells at the Site includingall monitoring wells installed during the Phase III RI. This round of groundwater samplingwas the most extensive at the Site to date. Samples were analyzed for TCL volatile andsemi-volatile organics, Pesticides/PCBs, and total and dissolved TAL metals. A list of allmonitoring wells sampled during Phase HI of the RI is provided in Table 5. Details ofPhase III groundwater sampling have been submitted in the WP III and the DSR III.

222 Groundwater Seepage

As a supplement to the monitoring well sampling, groundwater samples were also collectedfrom 12 of the approximately 20 areas of groundwater seepage identified on the north bankof the Christina River adjacent to the CIBA-GEIGY operations area and the NorthDisposal site during the third phase of the investigation. These samples of intertidal zonegroundwater discharge were analyzed for TCL volatiles and semi-volatiles, and total anddissolved TAL metals, as presented in Table 6. Details regarding the groundwater seepsand the procedures used for the collection of these samples are presented in the WP HI;results are presented in the DSR HI.

RI Rpt/Scctl-3/88C207fr4W/DPN4 2-3 5-28-92

RR3IUI75


Independent from the RI sampling conducted under the Superfund program, CIBA-GEIGYcollected composite groundwater seepage samples (after completion of DSR III) along thenorthern riverbank and analyzed for TCL organics and TAL metals. The analytical resultswere generally comparable to Du Font's sampling results (except CIBA-GEIGY VolatileOrganic's concentrations were somewhat lower - probably due to compositing). A summaryof the analytical results are provided in Appendix B. Neither the sampling methodology northe laboratory analyses were conducted with the intent of being in accordance with the SiteWork Plan or Quality Assurance Project Plan.

223 Residential Wells

In conjunction with groundwater sampling at the Site, public water supplies in the vicinityof the Site were surveyed and residential wells were sampled to provide additionalgroundwater chemistry data off-site. During Phase I of the RI, WCC conducted a surveyof the water supplies in the vicinity of the Site. The supplies identified during the surveyincluded two public water supplies (Artesian Water Company and Wilmington SuWater Corporation), and 19 private/residential wells along Old Airport Road. Groundwsamples were collected from two private welJs-aleag--Qld Airport Road on December 16,1987. The samples were analyzed forxJISlTorgluTicT nd-"metals and sulfate as SO4. Theresults of the water supply survey andihe groundwater sampling were submitted to the EPAin the WP. During WCC's inventory effort in December 1987, no residents stated that theyuse the groundwater from their wellslalong Old Airport I<oad for drinking water.

During Phase II, groundwater samples from ten residential/private wells located southwestof the Site along Old Airport Road were cbtiectedto provide additional data on the off-sitegroundwater chemistry (Figure 6). Representative wells were selected for sampling on thebasis of reported well depths and distances from the Site such that groundwater samplescould be collected from three of the water-bearing zones at the Site (HydrostratigraphicUnits I, IDA, and IV; see Section 3.3.4.1 for description of the Hydrostratigraphic Unitsidentified during the RI for the Site). Details of this sampling effort are provided in Section2.3, and Attachments 1 and 2 of the DSM.

RI Rpt/Sectl-3/88C20764W/DPN4 2-4

AR3UI76

5-2 2


As part of the Phase III RI, three rounds of groundwater samples were collected from fourEPA selected private wells on Old Airport Road (Figure 6). Groundwater samples werecollected from these wells on April 20 and May 15, September 29 and December 14,1990,and analyzed for TCL volatiles, and total and dissolved TAL metals. Detailed samplingprocedures used for this sampling effort were submitted in Appendix H of the DSR III.

2.3 RIVER WATER SAMPLING

Thirteen water samples were collected from the Christina River at the James Street Bridgeduring one complete tidal cycle during the first phase of the investigation. These samples(RW-1 through RW-7, RW-7A and RW-8 through RW-12) were analyzed for HSLparameters. Results of these analyses were presented in the WP.

2.4 SOIL INVESTIGATIONS

During the course of the RI, soil borings and other activities related to soil sampling wereperformed for the purposes of identifying subsurface materials, characterizing the physicalproperties of soils and collecting soil samples for chemical analyses. The soil investigationsconducted during the three phases of the RI are summarized in Table 7. Figure 7 presentsthe locations of the soil borings, test pit excavation in the South Disposal site, and surfacegrab sampling performed at the Site.

A total of 18 deep test borings were performed at the Site during Phase I (7) and Phase HI(11) of the RI (see Figure 7). The borings were advanced to the top of weathered bedrockat all locations except TB-26. Soil samples were collected from each of the boring locationsto provide data on stratigraphy and to identify water-bearing zones to be screened bymonitoring wells. Borehole geophysics (see Section 2.5) was also performed on each ofthese borings to provide a continuous record of stratigraphy at each location and to aid inthe selection of water-bearing zones.

Analytical samples were collected from 15 of the 18 Phase I and Phase HI deep test borings(all except TB-20, TB-21, and TB-26) for analyses that included TCL volatiles and semi-

RI Rpt/Sectl-3/88C2076-4W/DPN4 2-5 . 5-28-92

AR3IU77


volatiles, and TAL metals. A summary of the sampling frequency and the analysesperformed on each sample is presented in the WP for TB-1 through TB-7, and in the DSRIII for TB-20, TB-21, TB-26, and TB-28 through TB-35. These reports also present theanalytical results for samples collected from these test borings, respectively. The DSMpresents the results from the Phase II soil borings, which did not involve the depth orgeophysical logging to which the Phases I and III deep borings were subjected.

Twenty-three soil borings (B-l through B-22 and B-25) were advanced to the top of thePotomac Formation across the historic operations area of the Site. Samples were collectedat each location to gather stratigraphic information and for analyses that included TCLorganics and TAL metals. The data collected from these borings is presented in the DSRIII. In addition, nine shallow soil borings were performed by Duffield and Associates forCIBA-GEIGY during 1988. These borings were all performed in the eastern half of theCIBA-GEIGY Newport Plant. Analyses performed on these borings (EA-1 through EA-9)included Priority Pollutant volatile organics plus methanol and ethanol, and PriorityPollutant metals plus vanadium. Further discussion of the Duffield borings arein the DSM.

Six soil borings (SBND-1 through SBND-6) were performed across the North Disposal siteto characterize the wastes in that landfill. Analytical samples were collected at two- tothree-depth intervals within the fill material and analyzed for TCL organics and TAL p- als.Shallow soil samples (0 to 6 inch) were also analyzed for physical parameters. A GeigerCounter was also used to evaluate each sample for any radiation associated with the TD? Nickel buried in the landfill and select samples were analyzed for thorium-232 on the basis> of location relative to thoriated nickel wastes disposal areas. The results of this study are, presented in the DSM.

Eight Soil borings (SBSD-1 through SBSD-9) were advanced through the cap material acrossthe South Disposal site to determine the cap material thickness as well as the compositionof the cap. Samples were sent to a laboratory and analyzed for grain-size distribution.Results of this study are also presented in the DSM.

RI Rpt/Scctl-3/88C20764W/DPN4 2-6

AR3UI78

woodward-ClydeConsultants

Eight test pits (TP-1 through TP-8) were excavated in the South Disposal site during thefirst phase of the RI to characterize the Lithopone wastes disposed of in that area and toevaluate the near surface cover material. The tests pits were excavated to a depth of 8 to10 feet below ground surface. One sample was collected from each test pit and analyzedfor EP Toxicity metals and reactive sulfide. The complete HSL was also analyzed for in /,samples collected from TP-2 through TP-8. Samples collected from TP-2 and TP-5 werej\collected from the cover material that exists across the South Disposal site (at a thickness' *l (of up to 6 feet); the remainder of the samples were collected from the Lithopone wastematerial. The WP presents a full discussion of the results of these analyses.

Six surface soil samples (0 to 6 inches below ground surface) were collected at the Site todetermine background metals concentrations in soil (SGS-1 through SGS-4) and toinvestigate the vegetationless areas on the North Disposal site and adjacent to well clusterMW-3 (SGS-6 and SGS-5, respectively). The samples were analyzed for TCL organics(except volatiles) and TAL metals.

Eight soil samples were collected from four soil borings advanced to the water table at theHolly Run Plant during Phase III of the RI. The purpose of the borings was to characterizethe soils of the Holly Run Plant in preparation for the expansion of a building at the facility.Analyses included TCL organics, TAL metals, Reactivity, Corrosivity, Ignitability, TCLPorganics, and TCLP inorganics.

Twenty-seven soil samples were collected from 13 locations to a depth of 30 inches or lessin the Ballfield to the north of the Site (Figure 8). The samples were analyzed for TALmetals.

2.5 BOREHOLE GEOPHYSICS

Borehole geophysical logging was conducted at the Du Pont-Newport Site in conjunctionwith Phases I and III of the RI. The purpose of the geophysical logging programs was toidentify potential water-bearing zones between the ground surface and the decomposedbedrock beneath the Site, and to assess the continuity of the hydrostratigraphic units


HR3UI79


identified during the RI across the Site. The logging also served, along with other geologicinformation, as a basis for the selection of screened intervals in Phase I and Phase IIImonitoring wells.

During Phase I, seven boreholes were logged (TB-1 through TB-7) at both the North andSouth Disposal sites at the locations shown on Figure 7. The suite of geophysical logsconducted at these locations during Phase I are listed below.

• Single Point Resistance Log• Natural Gamma Log• Epithermal Neutron Log• Compensated Density Log• Caliper Log

The seven boreholes logged during Phase I were drilled as part of the Phase I monitoringwell installation program and were eventually converted into monitoring wells. The res;of the Phase I geophysical logging were presented in Appendix A of the WP.

During the Phase HI RI, borehole geophysical logging was conducted on 11 pilot holes(TB-20, '. TB-26 and TB-28 through TB-35) drilled as part of the Phase III monitoringwell instai i program (Figure 7). Each of the pilot holes was terminated at the base ofthe Potomat ormation, with the exception of TB-26, which was terminated at the base ofHydrostratigraphic Unit III within the Potomac Formation. The purpose of the Phase IIIgeophysical logging was, again, to identify potential water-bearing zones and to select depthsto install Phase III monitoring well screens. Sixteen-inch resistivity logs were run on allPhase HI pilot holes in addition to the suite of geophysical logs run in the Phase Iinvestigation. The results of the Phase III geophysical logging were previously submitted inthe DSR HI.

RI Rpt/Ssctl-3/88C20764W/DPN4 2-8 5-1

AR3IM80

VttT


2.6 SURFACE SURVEYS

As part of the Remedial Investigation, surface surveys were conducted to characterizeselected areas of the Du Font-Newport Site including soil gas, and surface geophysical andradiometric surveys. A summary of these programs is provided below. The areas coveredby the various surface surveys are presented on Figure 9.

2.6.1 Soil Gas Survey

A soil gas survey was performed at the Du Pont-Newport Site during June and July 1987 aspart of the Phase I RI. The purpose of the survey was to delineate possible trichloroetheneand tetrachloroethene vapor concentrations in the soils at the North and South Disposalsites. Soil gas samples were collected at points along a 100-foot grid pattern at both sitesand analyzed using a field operable gas chromatograph (GC). The results of the soil gassurvey are presented in Appendix G, of the WP.

2.6.2 Surface Geophysical Surveys

As part of the Phase I RI, surface geophysical surveys were performed over both the Northand South Disposal sites. The surveys conducted during June and July 1987 includedresistivity soundings using an ABEM COPCO Terrameter and a Schlumberger electrodeconfiguration, and terrain conductivity surveys using the Geonics EM-31 instrument. Thepurposes of the surveys were to increase the understanding of near surface stratigraphy andto better define the vertical and lateral extent of waste materials disposed at the twolandfills. The results of the surface geophysical surveys were presented in Appendix F ofthe WP.

2.6.3 Radiometric Surveys

Various radiometric or radiological surveys were conducted at the Site before the RI andduring Phases I and II of the RI. The purpose of the radiometric surveys was to monitor


Afl3|l)l8l


for any surface manifestation of radioactivity associated with the thorium wastes which areburied within the area of the North Disposal site.

During 1979 and 1980, Du Pont conducted at least two radiometric surveys using aVictoreen 471 radiation meter (Geiger Counter). The survey results (provided in the WP)in each case showed no sustained readings above background levels.

A ground radiometric survey was performed at the North Disposal site during the Phase IRI using a portable gamma-ray spectrometer and a Ludlum radiation meter. The objectiveof this survey was to verify that no high levels of gamma radiation from the buried thoriumwaste in the North Disposal site existed. The results of the Phase I radiometric surveyswere presented in the WP.

A radon-222 gas sampling survey was also conducted in a limited area of the North Disposal•

site during Phase I. The purpose of the radon gas survey was to provide a check on theoccurrence of uranium-238 in comparison with the field radiometric survey conductedthe portable gamma-ray spectrometer. The results of radon gas sampling werepresented in the WP.

During Phase II of the RI, subsurface radiological data were collected at three boringlocations at the North Disposal site to characterize the level of activity in waste materials.This work was conducted concurrent with a Phase II waste characterization program. Fillmaterial samples were analyzed for thorium-232 and its daughter products. In addition, agroundwater sample was collected from a monitoring well (SM-4) and analyzed for radium-228. The results of the Phase II radiological investigation were previously submitted in theDSR.

2.7 AQUIFER TESTING

Two constant rate aquifer tests were conducted during August 1987 as part of the Phase IRI. The primary purpose of the tests was to estimate the groundwater transmissivity andstorage coefficients of Hydrostratigraphic Unit IIIA (Intermediate Zone) of the Potomac


AR3UI82


Formation (see Section 3.3.4.4 for a discussion of the Hydrostratigraphic units identified byWCC). The hydraulic characteristics of Unit IIIA were evaluated by separately pumpingtwo monitoring wells, MW-3B and MW-6B, and monitoring water levels in adjacentobservation wells. A secondary goal was to estimate the vertical hydraulic relationshipbetween the shallow and deeper water-bearing units. To determine the appropriate flowrate prior to the constant rate tests, step-drawdown aquifer tests were conducted at both ofthe pumping wells. The data and evaluations for the aquifer tests were submitted in theWP, along with additional interpretations regarding groundwater discharge in the DSM.

2.8 WETLANDS INVESTIGATIONS

Investigations of a segment of the Christina River and the associated wetlands anddrainageways in the vicinity of the Site were conducted during Phases I, II, and III of theRI. A Supplemental Phase III Wetlands Investigation was also conducted. Table 8summarizes the field investigation activities from Phases II, III and Supplemental Phase III.The locations of river and wetlands stations sampled during these investigations are shownon Figures 10 and 11, respectively. The field verified boundaries of the wetlands areasassociated with the Site study area are shown on Figure 12. The objectives and categoriesof field activities for each phase of wetlands investigations are described below. Thedocuments in which complete data, evaluations, and literature references can be found arealso provided.

2.8.1 Phase I Wetlands Investigation

In conjunction with Phase I of the RI, a Christina River investigation and a wetlandsinvestigation were conducted during June through August 1987 and December 1987,respectively. These initial investigations included coring and analyzing river sediments forHSL parameters, monitoring tidal river level change, evaluating the hydrologiccharacteristics of the river segment near the Site, the collection and analysis of HSLparameters for hourly samples of Christina River water over a 12-hour period, and a fieldreconnaissance of the wetlands along the south shore of the Christina River adjacent to theSite. The results of these efforts are provided in the WP.


*«j - -^ AR311*183


2.8.2 Phase II Wetlands Investigation

An investigation of the sediment and surface water chemistry of wetlands and sections ofthe Christina River were conducted during Phase II of the RI. The Work Plan for thePhase II Wetlands Investigation was submitted as a portion of the RI/FS Work Plan anddescribed aquatic biological investigations to be performed in the Christina River andwetlands associated with the North and South Disposal sites.

The investigation was conducted in August 1988 and results were compiled in the WI, datedMarch 23, 1989. The objectives of the Phase II sampling efforts were: to obtain sufficientdata to estimate the extent to which zinc, barium and cadmium have dispersed in theChristina River and associated wetlands; and to develop data for use in evaluating the on-site biological pathways for chemical constituents at the Site.

2.83 Phase III Wetlands Investigation

Subsequent to review of the Phase II Wetlands Investigation Report by the EPA1989) and a meeting held between the EPA, Du Pont, and WCC on May 2, 1989, anagreement was reached that an additional study of the Christina River and wetlandsadjacent to the North and South Disposal sites was needed to supplement and clarify datacollected during Phase II, and further assess the environmental impacts and ecological risksassociated with the Site. Therefore, WCC conducted a Phase III Wetlands Investigationduring August and December of 1989. Results were presented in the WI in.

Included in the study were: the collection of sediments to determine physical characteristics,levels of radium-228, and concentrations of TAL metals; the assessment of relative toxicityof the sediments to aquatic biota; and the characterization of resident benthic communities.Also included were the verification of wetlands boundaries, the collection of fish for tissueanalyses, and the collection of field filtered and non-filtered surface water samples.



2.8.4 Supplemental Phase III Wetlands Investigation

In response to the EPA comments on the January 1990 Wetlands Report (WI III), aSupplemental Phase III Wetlands Investigation was conducted during October andNovember of 1990. The overall objective of the Supplemental Phase III WetlandsInvestigation was to evaluate the relative toxicity of Christina River and wetland sedimentsin the Site vicinity to aquatic biota in order to complete the database necessary to performthe environmental evaluation.

The Supplemental Investigation included sampling and analysis of seven new samplingstations for surface water and sediment. This phase of the investigation included thefollowing field investigations and laboratory analyses: surface water chemistry includingsources of organic carbon, sediment chemistry and physical parameter analyses, sedimenttoxicity testing, benthic community surveys, vegetation bioaccumulation, and analyses of fishtissue from the Christina River. The results of the Supplemental Phase in WetlandsInvestigation are provided in the DSR HI.

RI Rpt/Sectl-3/88C207fr4W/DPN4 2-13 5-28-92

Documents

Woodward-Clyde Consultants - Superfund Records · PDF fileWoodward-Clyde Consultants Engineering & sciences applied to the earth & its environment May 28, 1992 88C2076-4W Mr. Brandt