FINALPhase II Remedial InvestigationRemedial Action AlternativesTechnical MemorandumGambell, St. Lawrence Island, AlaskaContract No.DACA85-93-D-0011Delivery Order No.0013November 6, 1995Prepared for:Department of the ArmyUnited States Army Engineer District, AlaskaCorps of EngineersP.O. Box 898Anchorage, Alaska 99506-0898Prepared by:Montgomery Watson4100 Spenard RoadAnchorage, Alaska 99517200-leF10AK069603_03.10_0002_aTABLE OF CONTENTSExecutive Summary11.0 Introduction1.1 Background1.2 Objectives1.3 Results of Previous Investigations55892.0Areas and Contaminants of Concern2.1 Descriptions of Areas of Concern10113.0Recommended Actions164.0 Interim Removal Actions (IRAs)4.1 Recommended Interim Removal Actions28285.0 Conclusions326.0 References34Appendix AAppendix BApplicable Federal, State, and Local Regulations, and Benchmark ScreeningCriteriaPotential Remedial AlternativesGambell Technical Memorandum - FINAL/mg.OlC.40Q page iLIST OF FIGURESES-l12345Location of Investigative Sites and Areas of ConcernLocation Map - GambellGambell Investigative SitesAreas of Concern at Sites 2, 3, 4, and 5 - GambellAreas of Concern at Sites 6 and 7 - GambellRecommended Action Decision Tree367121517LIST OF TABLES123456789Summary of Areas of ConcernSummary of Remedial Considerations, Site 2Summary of Remedial Considerations, Site 3Summary of Remedial Considerations, Site 4BSummary of Remedial Considerations, Site 4DSummary of Remedial Considerations, Site 5Summary of Remedial Considerations, Site 6Summary of Remedial Considerations, Site 7Summary of Recommended ActionsGambell Technical Memorandum - FINAL/mg.OlC.40132122232425262733Q page iiLIST OF ACRONYMS2,3,7,8-TCDDARARsBD/DRBTEXCACDAPCERCLACOCCOECON/HTWCWADERPdioxinsDODDROE&EEE/CAEPAFUDSfuransGROHTWffiUBKIRAPCBspptQAQCRBCsRCRARfDRIRI/FSSOWSVOCsTCDDTRPHTSCATSDFURSVOCs2,3,7,8-tetrachlorodibenzo-p-dioxinApplicable or Relevant and Appropriate RequirementsBuilding Demolition and Debris RemovalBenzene, Tolune, Ethylbenzene, XylenesCorrective ActionChemical Data Acquisition PlanComprehensive Environmental Response, Compensation, and Liability ActContaminants of ConcernU.S. Army Corps of EngineersContainerized Hazardous or Toxic WasteClean Water ActDefense Environmental Restoration ProgramPolychlorodibenzo-p-dioxinsDepartment of DefenseDiesel Range OrganicsEcology and EnvironmentEngineering Evaluation/Cost AnalysisEnvironmental Protection AgencyFormerly Used Defense SitepolychlorodibenzofuransGasoline Range OrganicsHazardous or Toxic Waste?see page A-3Interim Removal ActionsPolychlorinated Biphenylsparts per trillionQuality AssuranceQuality ControlRisk-Based ConcentrationsResource Conservation and Recovery ActReference DoseRemedial InvestigationRemedial Investigation and Feasibility StudyScope of WorkSemi-Volatile Organic CompoundstetrachlorodibenzodioxinTotal Recoverable Petroleum HydrocarbonsToxic Substance Control ActTreatment Storage and Disposal Facilitymicrograms per kilogramURS CorporationVolatile Organic CompoundsGambell Technical Memorandum - FINAL/mg.OlC.40Q page HiEXECUTIVE SUMMARYGambell is located on the northwest tip of St. Lawrence Island, in the western portion of theBering Sea approximately 200 air miles southwest from Nome, Alaska, and 39 air miles from theSiberian Chukchi Peninsula. The village of Gambell is built on a gravel spit which projectsnorthward and westward from the island. St. Lawrence Island, including the land which housedthe former military sites, are currently owned jointly by Sivuqaq, Inc., Gambell, Alaska; andSavoonga Native Corporation, Savoonga, Alaska. Non-native land on St. Lawrence Island islimited to State lands used for airstrips and related facilities in Gambell.A Remedial Investigation (RI) was conducted at Gambell by Montgomery Watson in July 1994.The RI was performed under contract to the U.S. Army Corps of Engineers (COE) in accordancewith the requirements of the Scope of Work (SOW) for Contract No. DACA85-93-D-0011,Delivery Order No. 3. Eighteen sites were identified as part of this RI effort and were eithersampled, or observed and photographed with a walk-through. This Remedial ActionAlternatives Technical Memorandum is written in accordance with Tasks 1-3 of Delivery Order13, which involves addressing areas where further collection of data is necessary at Gambell toresolve the extent of contamination, and identifying areas where presumptive technologies andinterim removal actions will reduce the risk to human health or the environment. The eighteensites evaluated at Gambell, including the Background Site, are listed below. Site 14, the NavyPlane Crash Site, was not visited during the 1994 RI investigation.Site 1-North BeachArea 1 A-Army Landing AreaArea IB-Air Force Landing AreaSite 2-Former Military Housing/Operations SiteSite 3-Former Communications FacilitySite 4-Sevuokuk MountainArea 4A-Quonset Hut AreaArea 4B-Former Radar StationArea 4C-Stream Drainage at South End of MountainArea 4D-Transformers in Mountainside DrainageSite 5-Former Tramway SiteSite 6-Military LandfillSite 7-Former Military Power Site/Former Motor PoolSite 8-West Beacb/Army LandfillSite 9-Asphalt Barrel Cache (evaluated with a site walk-through only)Site 10-Sevuokuk Mountain Trail System (evaluated with a site walk-through only)Site 11-Communications Cable Route (evaluated with a site walk-through only)Site 12-Nayvaghaq Lake Disposal SiteSite 13-Former Radar Power StationSite 14-Navy Plane Crash SiteSite 15-Troutman Lake Ordinance Site (evaluated with a site walk-through only)Site 16-Gambell Municipal Building SiteSite 17-Army LandfillsSite 18-Former Main CampBackground SiteGambell Technical Memorandum - FINALO page 1Comparison of contamination levels found at the Gambell site to benchmark criteria and/or sitespecific factors has resulted in the retention of the following discrete areas that are identified forfurther investigation or remedial action. These areas are shown on Figure ES-1, and are listedbelow along with a brief summary of the reason for concern:•Site 2 - elevated levels of lead and other metals were detected in surface soils;•Site 3 - diesel range organics (DRO), beryllium, and thallium were found at a depth of 5feet;•Site 4/Area 4B - 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) anc} several prioritypollutant metals were detected in surface soil;•Site 4/Area 4D - low levels of polychlorinated biphenyls (PCBs) were detected insediments in a mountainside drainage;•Site 5 - DRO and total recoverable petroleum hydrocarbons (TRPH) were detected insoils below the water table; and TRPH was detected in groundwater;•Site 6 - DRO was detected in groundwater;•Site 7 - DRO and TRPH were detected in soils in contact with groundwater; volatileorganic compounds (VOCs) were found in groundwater at low concentrations; surfacesoils contained elevated levels of lead; and•Debris qualified for removal as containerized hazardous or toxic waste (CON/HTW)were present at several locations at the Gambell site.Site-specific recommendations at the areas of concern are as follows:•Site 2 - Conduct additional surface soil sampling for priority pollutant metals in order todelineate the areal extent of elevated lead and other metals;•Site 3 - Further surface soil sampling should be performed to confirm the presence ofsurface contamination, refine the delineation of the area of concern, and assess the risk tohuman health or the environment;•Site 4/Area 4B - Perform a limited ecological and human health risk assessment toevaluate risks posed by low levels of dioxin and high levels of priority pollutant metals;•Site 4/Area 4D - Limited amounts of sediment will be removed if staining is encounteredupon removal of the three transormers;Gambell Technical Memorandum - FINALO page 2WEST BEACH\BERINGn ;mSITE(SuspectedAsphalt BarrelCache)SEAtICWIHI""" 'i- "-i fflimBIIIIIB.--"""™™'-''''"'"*!,,._*_...^_^_^11SITE 14[NAVY PLANE CRASH APPRQX, 7 MILES SOUTH), NOTE 4(Submerged)1DRO & TRPH IN SOIL TOGROUNDWATER INTERFACEPb IN SURFACE SQIL,VOCsIN GROUNDWATERTROUTMANLAKENAWAGHAQLAKEjSITE 12*--•-)•"-V• ' V V i ' , -"t