ACAT FOIA Repository 16

Proposed Plan for Remedial ActionGAMBELL FORMERLY USED DEFENSE SITESt. Lawrence Island, AlaskaUS Army Corpsof EngineersJuly 2004Alaska DistrictIntroductionGambellThe United States Army Corps ofEngineers (USACE) and the AlaskaDepartment of EnvironmentalConservation (ADEC) request yourcomments on this Proposed Plan. TheProposed Plan covers 38 sites. The sitesare shown on Figure 1.#1C222772625B 25A 16 202624 188B19 2115Troutman LakeAirs trip4B34EThe purpose of this ProposedPlan is to:•4A5•4D•118A910•••Bering Sea4C288D1312±Nto14Gambell Proposed Plan10000Juneau#1B2##Sevuokuk Mountain1A176FairbanksAnchorageFigure 1 – Site Location Map238C#Nome10002000 FeetJuly 2004Describe theenvironmentalconditions at each site.Describe the cleanuplevels for the sites.Describe the cleanupalternatives that wereconsidered.Present therecommended cleanupalternative for each site.Request publiccomment on thepreferred alternatives.Provide information onhow the public can beinvolved in finalcleanup decisions.Final decisions on thepreferred alternatives will notbe made until all commentssubmitted by the end of thepublic comment period, havebeen reviewed and considered.Changes to the preferredo Page 1alternatives may be made if public comments or additionaldata indicate that such changes would result in moreappropriate solutions. After considering all publiccomments, USACE will prepare a Decision Documentwhich describes the final selected remedy. The DecisionDocument will include responses to all significant publiccomments received in a section called the ResponsivenessSummary.Preparation of this Proposed Plan and the associated publiccomment period is required under Section 117(a) of theComprehensive Environmental Response, Compensation,and Liability Act (CERCLA), also known as "Superfund".Although the sites described in this Proposed Plan are notCERCLA sites, this project follows CERCLA guidance.The Department of Defense (DoD) is tasked with correctingenvironmental damage caused by past military activities.The Defense Environmental Restoration Program (DERP)was set up to accomplish this task. The cleanup of FormerlyUsed Defense Sites (FUDS) is a part of this program. FUDSare those properties that the Department of Defense onceowned or used, but no longer controls. These propertiesrange from privately owned farms to National Parks. Theyalso include residential areas, schools, colleges, andindustrial areas. The FUDS program includes former Army,Navy, Marine, Air Force, and other defense properties. Over600 FUDS have been identified in Alaska.A Glossary of Terms is located at the end of this document.Site Location and BackgroundThe Native Village ofGambell is located on St.Lawrence Island, in thewestern portion of the BeringSea, approximately 200 airmiles southwest of Nome,Alaska (see Figure 2). Thevillage is situated on a gravelspit that projects north andwestward from the island, atan elevation of 30 feet abovemean sea level. St.Lawrence Island is currentlyowned jointly by Sivuqaq,Gambell Proposed PlanSites:1A North Beach1B Army Landing Area1C Air Force Landing Area2 Military Burial Site3 Communications Facility4A Air Force Radar Site4B Former Quonset Huts4C Discarded Drums4D Former Transformers4E Western Face of Sevuokuk Mtn5 Tramway Site6 Military Landfill7 Military Power Facility8A Marston Matting8B Buried Debris8C Navy Landfill8D Ammunition Beach Burial9 Asphalt Drums10 Army/Air Force Trails11 Communication Cable Route12 Nayvaghat Lakes Disposal Site13 Radar Power Station14 Navy Plane Crash Site15 Troutman Lake Disposal Site16 Municipal Building Site17 Army Landfills18 Main Camp19 Diatomaceous Earth20 Schoolyard21 Toe of Sevuokuk Mountain22 Former CAA Housing23 Debris from High School24 South of Municipal Building25A Gambell South Housing Units25B Low Drainage Area26 Possible Debris Burial Site27 Drum Storage Area28 Disturbed GroundAlaska Department of Environmental Conservation (ADEC): The stateagency responsible for protecting public health, safety, welfare, and theenvironment from adverse effects of environmental contamination.CERCLA: The Comprehensive Environmental Response, Compensation,and Liability Act (also known as Superfund). The federal law that guidescleanup of hazardous waste sites.Formerly Used Defense Site Program (FUDS): A Department ofDefense program to correct environmental damage caused by pastmilitary activities.Proposed Plan: A document informing Tribes, community leaders, andthe public about contaminated sites, cleanup alternatives that wereconsidered, and which alternatives were identified as the preferredalternatives.Decision Document: Identifies the selected remedy for a site, therationale for its selection, and includes responses to public comments.July 2004o Page 2Inc., in Gambell, Alaska, and the Savoonga Native Corporation in Savoonga, Alaska. NonNative land on St. Lawrence Island is limited to state land used for airstrips and related facilitiesin Gambell and Savoonga. During the 1950s, the military constructed and operated facilities inGambell as part of a surveillance and intelligence gathering network.Gambell is inhabited primarily byNative St. Lawrence Island Yupikpeople, who lead a subsistencebased lifestyle. The Gambell areasupports habitat for a variety ofseabirds, waterfowl, and mammalsthat either breed in or visit thearea. The area surrounding the topof Sevuokuk Mountain, above theVillage of Gambell, supports alarge bird rookery. The birds andbird eggs serve as a subsistencefood source for local inhabitants. The ocean surrounding the Gambell area is used extensivelyfor subsistence hunting of whales, walrus, seals, sea birds, and fish.Figure 2 – Gambell Location mapEnvironmental Investigation and Cleanup HistoryEnvironmental investigations and cleanupactivities at Gambell have been ongoingsince the mid 1980’s. The actions presentedin this Proposed Plan are based largely onthe investigations from 1994 to the present.The investigations have been performed inmany phases, with each new phase buildingon the previous phases. The goals of theinvestigations were to locate and identifyareas of contamination and to gather enoughinformation to develop a cleanup plan.The results of the studies are summarized inthis Proposed Plan. The original documentscan be found in the Administrative Recordlocated at the USACE Office on ElmendorfAir Force Base or at the InformationRepositories located in Gambell, Savoonga,Nome, and Anchorage.Administrative Record: A collection of historicaldocuments such as reports, studies, and maps whichsupport the final cleanup decision for a site.Feasibility Study (FS): A study to develop andevaluate options for remedial action, using datagathered during the RI. The study defines the objectivesof the response action, develops remedial actionalternatives, and conducts an initial screening anddetailed analysis of the alternatives.Geophysical Survey: A method used to delineateunderground features such as metallic debris.Information Repository: A publicly accessiblelocation where historical documents are stored.Remedial Investigation (RI): A process to determinethe nature and extent of contamination. The RIemphasizes data collection and site characterization,includes sampling and monitoring, as necessary.Removal/Remedial Actions (RA): Actions taken toabate, prevent, minimize, stabilize, mitigate, oreliminate the release or threat of release.The first major environmental study, the remedial investigation, was performed at Gambell in1994. The study separated the area into 18 sites. The results of the remedial investigationshowed that contaminants were present at some but not all sites.In 1996, Phase II of the remedial investigation was performed. In this study, additional soil andgroundwater samples were collected from Sites 1A, 1B, 2, 3, 4B, 4D, and 5. The studyGambell Proposed PlanJuly 2004o Page 3objectives were to further delineate the extent of contamination, estimate amounts of debris, andconduct a geophysical survey.In 1997, Montgomery Watson removed all visible surface debris from the island. After thisremoval action, frost jacking brought additional debris to surface. During the 1999 field season,Oil Spill Consultants, Inc. (OSCI) performed additional cleanup activities at various sites inGambell. OSCI removed a total of 26.8 tons of hazardous and non-hazardous containerizedwastes such as asphalt drums, paint, generators, batteries, empty drums, and transformercarcasses; removed 71 tons of exposed metal debris such as runway matting, cable, fuel tanksand equipment parts; and excavated 72 tons of contaminated soil.In 2000 and 2001, the Army Engineering and Support Center (Huntsville) conducted extensiveresearch and investigations to locate possible ordnance and explosives materials left behind bythe military. During the field surveys, very little ordnance waste was found, consisting primarilyof highly weathered 30-caliber small arms ammunition at a beach burial pit southwest ofTroutman Lake.A supplemental remedial investigation was conducted by Montgomery Watson Harza during the2001 field season, to investigate the nature and extent of contamination at four newly identifiedsites, and verify previously collected confirmation data. The summary report recommendedfurther action at several sites, and no further action for others.REMEDIAL ACTION OBJECTIVES AND CLEANUP CRITERIAAs part of the remedial investigation process, the level of contaminants are compared to risk-basedscreening levels and applicable regulatory cleanup levels. The Alaska Department ofEnvironmental Conservation (ADEC) regulates cleanup of contaminated sites, and has establishedsoil and groundwater cleanup levels (18 AAC 75). The soil cleanup levels for the majority of sitesin Gambell are the ADEC Table B cleanup levels, based on the Under 40 Inch Zone, Ingestionpathway. The ADEC concurs with the selection of Ingestion cleanup levels.The soil cleanup levels for Sites 5 and 12 only are theADEC Table B cleanup levels, based on the Migrationto Groundwater pathway. The groundwater cleanuplevels for Sites 5 and 12 are the ADEC Table C cleanuplevels. Table 1 lists the cleanup levels for the Gambellsites. The selected soil and groundwater cleanup levelsfor all sites are risk based and designed to be protectiveof human health and the environment.Screening Level: A number used forcomparison with data collected during aremedial investigation. Screening levelscan be the most conservative ADEC TableB cleanup level (migration to groundwaterpathway) or a risk-based level publishedby the US EPA.Cleanup Level: A site-specific number,selected based on the most relevantexposure pathway.Cleanup levels based on the migration to groundwaterpathway were not selected for sites other than Sites 5and 12 because in general, continuous permafrost acts as a barrier for soil contaminant migrationto a groundwater zone. However, migration of contaminants can occur via seasonal groundwaterpresent in the active lens above the permafrost layer (suprapermafrost groundwater).Suprapermafrost groundwater has been sporadically documented within the village of Gambell(i.e. in the vicinity of Sites 6, 7, 16, 17, 18). The groundwater flow direction from these areas isnorth, towards the Bering Sea, a distance of about 1,200 feet away. The groundwater aquifer thatGambell Proposed PlanJuly 2004o Page 4supplies drinking water to thecommunity is located at the base ofSevuokuk Mountain, approximately1,500-2,000 feet east of the village.Table 1. Soil and Groundwater Cleanup LevelsAll SitesSites 5 and 12SoilSoilDRO10,250 mg/kg DRO250RRO10,000 mg/kg GRO300Antimony41 mg/kg RRO11,000Arsenic5.5 mg/kg Arsenic2.0Beryllium200 mg/kg Cadmium5Cadmium100 mg/kg Chromium26Chromium300 mg/kg Lead400Copper4,060 mg/kgLead400 mg/kg GroundwaterMercury18 mg/kg DRO1.5Nickel2,000 mg/kg GRO1.3Selenium510 mg/kg RRO1.1mg/kgmg/kgmg/kgmg/kgmg/kgmg/kgmg/kgThe sites located at the top ofSevuokuk Mountain – Sites 4A and4B – are situated on bedrock. Verylittle soil is found at the top ofSevuokuk Mountain andgroundwater is expected to run offmg/Lmg/Lthe side of the mountain or entermg/Lbedrock fractures. It is unlikely thatgroundwater from Sites 4A and 4B could impact the drinking water aquifer at the base of themountain.Groundwater from the central gravel spit is not suitable as a source of drinking water.Groundwater in the gravels is often saline, difficult to recover in useable quantities, and locatedin an active lens over permafrost. Drinking water wells installed in the gravel have beenabandoned in the past. Groundwater encountered at the site has been limited in quantity, andonly intermittently detected. Permafrost in Gambell is commonly encountered at depths rangingfrom 3 to 15 feet below the ground surface. The village water supply is located at the base ofSevuokuk Mountain, on the far eastern edge of the gravel spit (see Figure 4). According to aState of Alaska hydrogeological investigation report (Ireland, 1994), the Gambell aquifer iscanoe-shaped, originating along the front of the steep bluff of Sevuokuk Mountain, andcontinuing down the hydrological gradient across a highly permeable gravel bar towards theocean. The aquifer appears to be a thaw bulb in the permafrost, and as the permafrost expands orrecedes, the aquifer dimensions vary. The influence of warm recharge water from SevuokukMountain has produced the thaw bulb effect on the area permafrost. The majority of the waterrecharging the aquifer originates from two springs that flow from the steep bluffs of themountain into the gravel. Shallow groundwater across the gravel spit does not appear to becontinuous because of the presence of shallow permafrost (Munter and Williams, 1992).Site contaminant levels were compared to theselected cleanup levels. The US EnvironmentalProtection Agency (EPA) recommends calculatingthe 95% upper confidence limit (UCL) for sitespecific datasets. The 95%UCL represents areasonable estimate of the maximum concentrationlikely to be contacted over time.Gambell Proposed PlanJuly 200495% Upper Confidence Limit (UCL): thevalue at which there is a 95% likelihood that95% of the dataset is below this value (e.g.the upper boundary). The UCL is alsoconsidered a reasonable estimate of themaximum exposure concentration.o Page 5Aerial view of GambellGambell Proposed PlanJuly 2004o Page 6REMEDIAL ALTERNATIVESThe Corps of Engineers considered the following remedial alternatives for each site:No Further Action. No further action (NFA) is a response action selected when no additionalremedial actions are necessary to protect human health and the environment, based onestablished cleanup levels and regulatory standards. NFA is also used as a baseline to compareother responses.Institutional Controls. Institutional controls make use of restrictions to minimize exposure tocontaminants at a site. The restrictions can be physical, such as erecting a fence, or take the formof land management practices, such as requiring special building permits or not allowinginstallation of new wells in a particular area.Site-specific Actions. A feasibility study (FS) evaluated alternatives for Sites 4A, 4B, 6, 7, 8,and 12. The FS provided a detailed analysis of four alternatives for Sites 8 and 12.§ No Action§ Debris Removal Only§ Debris and Lead-Contaminated Soil Removal§ Debris Removal and In-situ Treatment of Lead-Contaminated SoilThe Corps of Engineers evaluated remedial alternatives based on the nine evaluation criteriaestablished under CERCLA, as shown in Table 2.Table 2. Nine Criteria for Evaluation of Alternatives Under CERCLACriteriaDefinitionOverall Protection of Human Health and How well does the alternative protect human health and the environmentthe Environmentthrough elimination, reduction, or control of contaminated areas?Compliance with Applicable or Relevant Does the alternative meet cleanup standards and comply with applicableand Appropriate Requirementsstate and federal laws?Short-term effectivenessAre there potential adverse effects to either human health or theenvironment during construction or implementation of the alternative?Long-term effectiveness andHow well does the alternative protect human health and the environmentPermanenceafter cleanup, and area there any risks remaining at the site?Reduction of Toxicity, Mobility, andDoes the alternative effectively treat the contamination to significantlyVolume through Treatmentreduce the toxicity, mobility, and volume of the hazardous substance?ImplementabilityIs the alternative both technically and administratively feasible? Has thetechnology been used successfully at similar areas?CostWhat are the capital and operating and maintenance costs of thealternative?Community AcceptanceWhat are the community’s comments or concerns about the alternativesconsidered and about the preferred alternative? Does the communitygenerally support or oppose the preferred alternative?State AcceptanceDoes the state regulatory agency (ADEC) support or oppose thepreferred alternative?Gambell Proposed PlanJuly 2004o Page 7SITE SUMMARIESThe following sections provide physical descriptions, investigative histories and preferredalternatives for each site. The general location of sites in the northern portion of Gambell isshown in Figure 3.Site 1A – North Beach, Army Landing AreaSite Description: This site is located in the central portion of the North Beach, where two wellestablished all-terrain vehicle (ATV) trails intersect. The Army landing area was located east ofan area that is currently used by local residents to land or launch whaling boats. The siteconsisted of exposed surface debris including engine pieces, marston matting, weasel tracks,steel cables, a partially buried 100-foot crane, and other buried metallic debris which areperiodically exposed and reclaimed by shifting gravels along the beach area.Cleanup Actions to Date: In 1997, Montgomery Watson removed all visible surface debris fromSite 1A (5,545 pounds) and the surrounding beach area (3,630 pounds), including corrugatedroofing material, piping, marston matting, weasel tracks, protruding parts of a buried crane,engines, cables, and other miscellaneous debris.Investigation Summary: The site was investigated during the 1994 Phase I remedialinvestigation, including a geophysical survey to delineate landfill boundaries, installation of fiveFigure 3 – Overview of Northern SitesNorth Beach1CArmy Landing AreaBERING SEA23 Debris fromHigh School8C Navy LandfillWestBeach8BBuriedDebrisFormerCommunicationsFacility1AArmy Landfills22CAAHousingOld VillageArea25BLowDrainageAreaAir ForceLanding Area176MilitaryLandfillDrum StorageArea27 Former7 PowerFacility2625AS. Housing 1620FormerAir ForceRadar Site1BFormer MilitaryBurial Site2VillageWaterSupply4B34ECableDebrisFormer4A Quonset Huts20245Former21Buried TramwayFormerDiatomaceous DebrisMain4D FormerEarthCampTransformersHighSchool181915CityHall WasheterianiuNGambell Proposed Plan050010Air For ce Tr ail9 AsphaltDrums500Army Trai lns C abl e Rout eTroutman Laketioca8AMarstonMattingCommAir str ip111000 FeetJuly 2004o Page 8monitoring wells, and collection of subsurface soil, surface soil, and groundwater samples.Several soil and groundwater samples were collected in 1994. One surface soil sample wascollected and analyzed for total recoverable petroleum hydrocarbons (TRPH), BNAs, PCBs, andpriority pollutant metals. Subsurface soil samples were analyzed for petroleum hydrocarbons(DRO, GRO, TRPH), VOCs, PCBs, and priority pollutant metals. Groundwater samples wereanalyzed for petroleum hydrocarbons (DRO, GRO,TRPH), VOCs, PCBs, and priority pollutant metals.BNAs: base, neutral, and acidcompounds (includes PAHs)Arsenic concentrations in soil ranged from 1 to 9 mg/kg.DRO: diesel range organicsThe average concentration (95% UCL) for arsenic is 5.0GRO: gasoline range organicsmg/kg, which does not exceed the cleanup level of 5.5PAHs: polynuclear aromaticmg/kg. No other contaminants were detected in soil orhydrocarbonsgroundwater above screening levels.PCBs: polychlorinated biphenylsCleanup Objective: ADEC Table B soil cleanup levelsbased on the Ingestion pathway.Preferred Alternative: No further action. There are nocontaminants which exceed the selected cleanup levels. Inaddition, Site 1A meets the more stringent ADEC cleanuplevels based on the Migration to Groundwater pathway.All dangerous surface debris was removed in 1997. Burieddebris is not eligible for further action under FUDS.priority pollutant metals: antimony,arsenic, barium, beryllium, cadmium,chromium, copper, lead, mercury,nickel, selenium, silver, thallium, zinc.RRO: residual range organicsSVOCs: semi-volatile organiccompoundsTRPH: total recoverable petroleumhydrocarbonsVOCs: volatile organic compoundsSite 1B – North Beach, Air Force Landing AreaSite Description: This site is located west of Sevuokuk Mountain, and approximately 1,900 feeteast of the Army Landing Area on North Beach. The site contained exposed surface debris, ruststained gravel, and a patch of tar-stained gravel. Additionally, buried debris may be periodicallyexposed as the gravel beach deposits shift or frost jacking occurs. This area receives a largeamount of ATV traffic due to its proximity to the bird rookeries on Sevuokuk Mountain visitedby local residents and tourists.Cleanup Actions to Date: In 1997, Montgomery Watson removed all visible surface debris fromSite 1B (105 pounds) and the surrounding beach area (2,865 pounds), including marston matting,empty drums, sheet metal, steel cables, and other miscellaneous debris.Investigation Summary: Site 1B was investigated during the 1994 Phase I remedialinvestigation, including a geophysical survey to delineate buried debris, installation ofmonitoring wells, and collection of surface soil, subsurface soil, and groundwater samples.In 1994, three monitoring wells were installed at Site 1B, to a maximum depth of 20.5 feet.Groundwater was encountered between 10 and 14.5 feet below ground surface. Subsurface soiland groundwater samples were collected from the three borings and analyzed for petroleumhydrocarbons (GRO, DRO, TRPH), VOCs, PCBs, and priority pollutant metals. One surfacesoil sample was collected from the rust-stained soil and analyzed for TRPH, BNA, PCBs, andpriority pollutant metals. Petroleum hydrocarbons and lead were detected in soil, but did notexceed screening levels. Arsenic was also detected in soil at concentrations ranging from 2 to 7mg/kg. The average concentration (95% UCL) of arsenic is 4.8 mg/kg, which does not exceedGambell Proposed PlanJuly 2004o Page 9the cleanup level of 5.5 mg/kg. No other chemicals were detected in soil or groundwater abovescreening levels.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. There are no contaminants which exceed the selectedcleanup levels. In addition, Site 1B meets the more stringent ADEC cleanup levels based on theMigration to Groundwater pathway. Therefore, no additional actions are proposed. Alldangerous surface debris was removed in 1997. Buried debris is not eligible for further actionunder FUDS.Site 1C – North BeachSite Description: This site covers the entire length of North Beach and consists of underwatermetallic debris located just offshore. The majority of the debris is thought to be marston mattingused to construct the two military landing areas. North Beach is the primary area used by localresidents for launching and landing boats.Cleanup Actions to Date: In 1997, Montgomery Watson removed all visible surface debris(10,105 pounds) from the entire length of the North Beach, including corrugated roofingmaterial, piping, marston matting, empty drums, heavy machinery parts, metal cables, and othermiscellaneous debris.Preferred Alternative: No further action. The remaining underwater debris is not eligible forfurther action under FUDS.Site 2 – Former Military Housing/Operations Burial SiteSite Description: Site 2 is located approximately 1,000 feet south of the former Air ForceLanding Area on North Beach, and just west of the base of Sevuokuk Mountain (see Figure 3).Facilities associated with military housing/operations, and a power plant, were reportedlydemolished and buried at this site. Ordnance may have been buried here as well. Exposed debriswas observed at the site, including remnants of a rock fireplace, partially buried concrete pad,burned wood, scattered metal debris/gear, and discolored gravel.Cleanup Actions to Date: In 1997, Montgomery Watson removed 100 pounds of miscellaneousdebris from Site 2, and a large quantity (total of 1,740 pounds) of cable spools, wheel rims,corrugated metal, and marston matting from the vicinity of Site 2 (between Sites 1A and 3). OilSpill Consultants, Inc (OSCI) removed the remaining exposed debris in 1999, but attributed allquantities of debris removed to Site 3. OSCI also removed 24,982 pounds (12.5 cubic yards) ofpetroleum-stained soils from near Site 2. The actual location of the stained soil was adjacent to alarge rock at the base of Sevuokuk Mountain, approximately 450 feet south of the Bering Sea/North Beach. This location was identified by Montgomery Watson as between Site 1A and 3.Investigation Summary: During the 1994 Phase I remedial investigation, a geophysical surveywas conducted, as well as installation of groundwater monitoring wells, and collection of surfacesoil, subsurface soil, groundwater, and asbestos samples.Gambell Proposed PlanJuly 2004o Page 10Three monitoring wells were installedTable 3. Sampling Results at Site 2ChemicalScreeningResultsResultsAverageat the site during the 1994aLevel(1994)(1996)(95%UCL)investigation; subsurface soil samplesSoil (mg/kg)were collected and analyzed forDRO250ND - 28-VOCs, GRO, DRO, TRPH, priorityTRPHNAND - 710-pollutant metals, PCBs, andArsenic23 - 11-6.5explosives. Groundwater samplesChromium263 - 391-82 – 165 bLead4001 - 7493.6-63206were collected and analyzed forWater (mg/L)VOCs, GRO, DRO, TRPH, priorityTRPHNA0.5-pollutant metals, and explosives.Notes: NA not available, ND not detectedaSurface soil samples were also18AAC75, Table B, Under 40 Inch Zone, Migration to Groundwater (August 8,2003)collected and analyzed for TRPH,brange of values based on non-parametric methodsBNA’s, and priority pollutant metals.Low levels of fuels were detected in the soil. Elevated levels of metals were also detected in onesurface soil sample above screening levels. Low levels of total hydrocarbons were detected inthe groundwater sample, but did not exceed ADEC cleanup levels. No other analytes weredetected in the groundwater or soil. No asbestos was detected in the fibrous material. Samplingresults are summarized in Table 3.Only one sample from 1994 exceeded the screening levels for chromium and lead. The 12 othersoil samples contained low levels of chromium (ND to 21 mg/kg) and lead (1 to 70 mg/kg).Chromium was not considered a contaminant of concern following the 1994 investigation.During 1996, further soil sampling was conducted to determine the extent of lead contamination.Eight surface soil samples were collected and analyzed for lead only. Sampling results areshown in Table 3. The 1996 results were significantly lower, indicating the 1994 sample was anisolated occurrence. The average lead concentration at the site does not exceed the ADECcleanup levels. The maximum chromium concentration is considered an outlier. See Table 3 fora summary of the Phase II results. Although the detected arsenic concentrations exceed theADEC cleanup level, the levels are consistent across many sites in Gambell, and do not appearassociated with past military activity.In 1999, OSCI collected a pre-excavation sample to characterize the stained soils for disposalpurposes; the sample contained gasoline and diesel range organics at 309 and 6,440 mg/kg,respectively. The concentration of petroleum hydrocarbons in the removed soils did not exceedADEC cleanup level based on the Ingestion pathway. No PCBs, VOCs, SVOCs, pesticide/herbicides, or leachable metals were detected. After OCSI removed a large quantity of stainedsoils, the Corps of Engineers stopped further excavation because the intent of the removal actionwas to remove limited stained soils associated with drums and other debris. The contaminationwas more extensive than previously indicated. In addition, the petroleum-stained soils were laterreported to originate from draining oil from locally ownedATVs. No post-excavation samples were collected,Leachable metals: Metals testedusing the toxicity characteristicbecause the Corps determined the stained soil wasleaching procedure (TCLP).erroneously included in the scope of work.Earth Tech, Inc. conducted two geophysical surveys at Site 2 during July and September 2000, todetermine the presence or absence of buried ordnance. First, the field team visually surveyed thearea and removed metallic scrap and debris from the surface. Next, metal detectors were usedmap the location of subsurface anomalies over three site grids. Each target location was thenGambell Proposed PlanJuly 2004o Page 11further investigated, excavated and searched for the source of the metallic anomaly. No evidenceof any ordnance was found during the investigation.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. There are no contaminants of concern present abovethe selected cleanup levels. The arsenic concentrations are attributable to background, and thesingle chromium exceedance is considered an outlier. Furthermore, the observed petroleumcontamination may be the result of more recent oil spills that are not related to former DoDactivities. The partially buried concrete pad is not eligible for further action under FUDS.Site 3 – Former Communications Facility Burial AreaSite Description: Site 3 is located approximately 700 feet south of the North Beach, near thebase of Sevuokuk Mountain (see Figure 3). The preliminary assessment indicated the possibleburial of Jamesway huts, power plant generators, transformers, oils, batteries, and sulfuric acid.Exposed above-ground debris included metal debris (weasel tracks, marston matting), some pipe,empty drums, and anchors for guy wire.Cleanup Actions to Date: In 1997, Montgomery Watson removed 1,740 pounds of debris fromthe vicinity of Site 3, including cable spools, corrugated metal, marston matting, and cable wires.In 1999, Oil Spill Consultants removed an additional 3,030 pounds of surface debris, includingweasel tracks, 3 empty fuel storage tanks, marston matting and drums.Investigation Summary: During the Phase Iinvestigation in 1994, Montgomery Watsoncompleted a geophysical survey to determinethe extent of buried debris, installed twomonitoring wells, and collected subsurfacesoil and groundwater samples.Table 4. Sampling Results at Site 3ChemicalCleanupResultsLevel(1994)Soil (mg/kg)DRO10,250 a522Arsenic5.5 a3-6Beryllium200 a6Cadmium100 a7Mercury18 b11Selenium510 a13Thallium5.5 d15Water (mg/L)Lead0.015 c0.045Lead, dissolvedND (0.002)Results(1996)ND (2.52)The geophysical survey identified twodiscrete areas with suspected buried material.ND (0.28)The monitoring wells encounteredgroundwater at depths of 8 to 9 feet belowground surface. An analysis of thegroundwater gradient indicated a northerlyNotes:a18AAC75, Table B, Under 40 Inch Zone, Ingestion (August 8, 2003)flow direction. Subsurface soil samples wereb18AAC75, Table B, Under 40 Inch Zone, Inhalation (August 8, 2003)ccollected at depths of 2.5 and 5 feet, and18AAC75, Table C (August 8, 2003)dUS EPA Region 3, Risk-Based Concentration Table (April 4, 2004)analyzed for petroleum hydrocarbons, VOCs,priority pollutant metals, PCBs, sulfate/sulfur, and pH. A low level of DRO was detected. NoVOCs or PCBs were detected. Several metals were detected in the soil, including arsenic,beryllium, cadmium, mercury, selenium, and thallium. Beryllium and thallium exceeded initialscreening levels, and further sampling was conducted during the Phase II investigation. Table 4summarizes the sampling results from Site 3.Lead was detected in groundwater from MW10 at a concentration which exceeds the ADECTable C groundwater cleanup value. However, a filtered sample from this well did not containGambell Proposed PlanJuly 2004o Page 12any dissolved lead. A second monitoring well, MW09, located immediately downgradient ofMW10 did not contain detectable levels of lead in the groundwater. Both monitoring wells arelocated downgradient of the village drinking water supply well. Lead was not identified as acontaminant of concern, and no further groundwater sampling was performed at Site 3 after thePhase I investigation.Additional investigation for beryllium and thallium was conducted during the 1996 Phase IIinvestigation. Four surface soil samples were collected; the results were all below detectionlimits. The thallium results from 1994 were determined to be anomalous and spatially limited.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. There are no contaminants of concern present abovethe cleanup levels. All dangerous surface debris has been removed. The buried debris is noteligible for further action under FUDS.Site 4A – Former Quonset Huts near USAF Radar StationSite Description: Site 4A consisted of collapsed Quonset Huts frames and transformer casingslocated on the top of Sevuokuk Mountain.Site 4A after removal actionCleanup Actions to Date: In 1997,Montgomery Watson removed the three emptytransformer carcasses. In 1999, OSCI removed14,772 pounds (7.4 tons) of debris, includingtwo collapsed Quonset hut frames, metal siding,drums, and associated stained soil (1,877pounds).Investigation Summary: This area was studiedduring the 1994 investigation. Three surfacesoil samples were collected adjacent to thefallen transformers and analyzed for PCBs.Asbestos samples were also taken around thefallen Quonset huts. No PCBs or asbestoscontaining material (ACM) were detected in thesoils.OSCI collected confirmation soil samples from within and outsideof the two Quonset hut footprints following the removal action.The samples were analyzed for petroleum hydrocarbons(DRO/RRO/GRO), VOCs, SVOCs, PCBs, pesticides, andResource Conservation and Recovery Act (RCRA) metals.Gambell Proposed PlanJuly 2004RCRA metals: arsenic,barium, cadmium, chromium,lead, mercury, selenium, silver.o Page 13The 1999 confirmation samples containedTable 5. Confirmation Sampling Results at Site 4AChemicalCleanupHighestHighestsome elevated diesel range organics andaLevelConcentrationConcentrationmetals. Arsenic, chromium, and lead(1999)(2001)were detected at concentrations exceedingSoil (mg/kg)the ADEC cleanup levels. AArsenic5.58.33.9supplemental investigation was done inChromium30039112.12001 at Site 4A to verify the previousLead40042244DRO10,2501,310970confirmation sampling results. FourNotes:samples were collected based on fielda18AAC75, Table B, Under 40 Inch Zone, Ingestion (August 8, 2003)screening results and analyzed forpetroleum hydrocarbons and RCRA metals. All chemicals were below ADEC cleanup levels.Table 5 summarizes the confirmation soil sampling results from Site 4A. No significant volumeof contaminated soil remains at the site. The area consists of large boulders on top of bedrockwith small amounts of soil.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred alternative: No Further Action. All hazardous debris and contaminated soil wereremoved during the 1997 and 1999 field seasons. Site 4A has been cleaned up to extent feasible,as there is minimal soil above bedrock.Site 4B – Former USAF Radar StationSite Description: Site 4B was a US Air Force (USAF) radar station, located on top of SevuokukMountain. The site covered an area approximately 375 feet by 500 feet. The radar stationconsisted of buildings that burned and caused ordnance to explode and scatter debris.Cleanup Actions to Date: In 1999, OSCI excavated 52 tons of contaminated soil to a depth of24 inches; and removed 1.4 tons of miscellaneous metal debris from Site 4B. The excavationarea was approximately 29 by 37 feet, partly covered by boulders, with localized heavy stainingand an oily substance.Investigation Summary: During the first phase of investigation in 1994, soil samples werecollected and analyzed for petroleum hydrocarbons (TRPH), PCBs, priority pollutant metals,BNAs, and dioxin/furans. The Phase I sampling results identified elevated concentrations ofmetals and dioxins. During the 1996 Phase II investigation, four additional surface soil sampleswere collected from the edges of the stained soil area to delineate the extent of metalscontamination. Samples were analyzed for antimony, arsenic, cadmium, copper, and lead. Theresults were significantly lower than those detected during the Phase I. See Table 6 for acomparison of results.Confirmation samples collected after the 1999 soil excavation were analyzed for petroleumhydrocarbons (DRO/RRO/GRO), VOCs, SVOCs, PCBs, pesticides, metals (antimony, arsenic,cadmium, copper and lead), and dioxin/furans. Sampling results are shown in Table 6. Theconcentration of dioxins decreased significantly as a result of removing the soils.In 2001, supplemental RI fieldwork was done at Site 4B to verify the 1999 confirmationsampling results because the referenced latitude and longitude coordinates were not documentedGambell Proposed PlanJuly 2004o Page 14Table 6. Comparison of Maximum Concentrations of Contaminants of Concern in Soil at Site 4BChemicalUnits199419961999 pre1999 post2001 postADECresultsresultsexcavationexcavationexcavationcleanupresultsresultsresultslevelaAntimonymg/kg130ND (15) -3.3-41Arsenicmg/kg3817-1.64.35.5Cadmiummg/kg526-1.80.4100Coppermg/kg26,6001,900-6,940-4,060b7,000c7,800dLeadmg/kg3,24984011.7 mg/L39696400(TCLP)Total Dioxinsµg/kg51.2-26234-NA(TEQ)Diesel Rangemg/kg--46913,90010,00010,250Organics (DRO)Residual Rangemg/kg--2,11090520010,000Organics (RRO)TRPHmg/kg690----NANotes:ND – non detect, TEQ – total dioxin/furan equivalent, TCLP – toxicity characterization leaching procedure, NA – not availablea18AAC75, Table B, Under 40 Inch Zone, ingestion pathway (August 8, 2003)bAdditional Cleanup Levels, ADEC Technical Memorandum 01-007 (November 24, 2003), ingestion pathwaycAdditional Cleanup Levels, ADEC Technical Memorandum 01-007 (November 24, 2003), migration to groundwater pathwaydU.S. EPA, Region 3, Risk-Based Concentration Table (April 14, 2004), residential soilby OSCI. Soil samples were collected and analyzed for petroleum hydrocarbons (DRO/RRO/GRO) and RCRA metals. The results are shown in Table 6. Antimony and copper were notanalyzed for in 2001 because they are not part of the standard set of 8 RCRA metals (arsenic,barium, cadmium, chromium, lead, mercury, selenium, silver).The 1999 results showed only 1 out of 6 samples exceeded the ADEC Table B cleanup level of4,060 mg/kg for copper, based on the ingestion pathway. The highest concentration of copper inthe remaining samples was 65.7 mg/kg. However, the maximum concentration of copper doesnot exceed the ADEC Table B cleanup level of 7,000 mg/kg based on the migration togroundwater pathway, or a risk-based concentration of 7,800 mg/kg for residential soil publishedby the US EPA, Region 3. The 1999 sample with elevated copper also contained lead. Furthersampling in 2001 indicated lead at much lower levels, but copper was not included in theanalytical suite.Site 4B (post-excavation)Cleanup Objective: The Feasibility Studyevaluated remedial action objectives for Site4B. Site 4B is located at the top ofSevuokuk Mountain, and is situated onbedrock. Very little soil is found at the topof Sevuokuk Mountain and groundwater isexpected to run off the side of the mountainor enter bedrock fractures. It is unlikelythat water from Site 4B would impact theaquifer at the base of the mountain.Therefore, the ADEC Table B soil cleanuplevels based on the Ingestion pathway wereselected.Gambell Proposed PlanJuly 2004o Page 15Preferred Alternative: No further action. No contaminants of concern remain above cleanuplevels. The elevated copper is an isolated occurrence, and de-minimus quantities of soil remainat Site 4B. The contamination does not pose a potential threat to the public drinking watersupply located southwest of the Site at the base of Sevuokuk Mountain, because the predominantdrainage pathway is north towards the Bering Sea.Site 4C – Sevuokuk MountainSite Description: Site 4C is located at the south end of Sevuokuk Mountain, and containeddiscarded drums along an ATV trail.Cleanup Actions to Date: Scattered drums were collected from along ATV trails and thesurrounding tundra at the southern end of Sevuokuk Mountain by OSCI during the 1999 fieldseason. OSCI removed a total of 12,516 pounds of drums and drum parts from the Army Trails(Site 10), which included the drums identified at Site 4C.Investigation Summary: Samples were collected and analyzed for PCBs during the Phase Iremedial investigation. No PCBs were detected.Preferred Alternative: No further action. All hazardous debris was removed during the 1999field season.Site 4D – Sevuokuk MountainSite Description: At this site near the top of Sevuokuk Mountain, three empty transformercasings and miscellaneous debris were observed in a mountainside drainage above the pumphouse.Cleanup Actions to Date: In 1999, Oil Spill Consultants removed the three empty transformersfrom Site 4D. Wipe samples collected from inside each transformer carcass did not contain anyPCBs.Investigation Summary: During the 1994 investigation, one soil and four sediment sampleswere collected and analyzed for PCBs. No PCBs were detected in the samples collected adjacentto the empty transformers. A background sample collected upgradient contained 0.194 mg/kgPCBs. In 1996, groundwater from a former infiltration gallery just downslope of Site 4D wassampled and analyzed for BTEX and PCBs. No contaminants were detected in the groundwater.Preferred Alternative: No further action. All hazardous debris was removed during the 1999field season.Site 4E – Western Face of Sevuokuk MountainSite Description: Various types of cable and wire are present on the ground surface along thesloped western face of Sevuokuk Mountain. The Native Village of Gambell identified this areaas an impacted site during preparation of a strategic project implementation plan for the NativeAmerican Lands Environmental Mitigation Program (NALEMP).Gambell Proposed PlanJuly 2004o Page 16Preferred Alternative: No further action. The debris is not eligible for further action underFUDS. However, NALEMP plans to address the remaining debris at this site.Site 5 – Former Tramway SiteSite Description: Site 5 is located at the base of Sevuokuk Mountain, northeast of TroutmanLake and near the Village water supply. The site was suspected to contain buried tram cables ortransformers.Cleanup Actions to Date: In 1997, the two geophysical anomalies were excavated. Oneanomaly contained debris from an abandoned Quonset hut and a battery, which were removed byMontgomery Watson and shipped off-site for disposal. The second anomaly contained seven 55gallon drums filled with gravel and wrapped with wire cable, apparently used as anchors for theformer tram system. No soil contamination was evident. The drum anchors were left in placeand reburied.Investigation Summary: Geophysical surveys were conducted in 1994, 1996, and 1998. Duringthe Phase I investigation (1994), four soil borings and two monitoring wells were installed at Site5. Soil samples were analyzed for petroleum hydrocarbons (DRO, GRO, TRPH), prioritypollutant metals, and PCBs. Groundwater samples were analyzed for petroleum hydrocarbonsand PCBs.The Phase I investigation results indicated DRO was present above screening levels in soil fromone monitoring well (MW16). Trace levels of DRO and TRPH were also detected in thegroundwater from this monitoring well, but did not exceed ADEC cleanup levels. Table 7summarizes the sampling results, and Figure 4 shows the monitoring well locations.Table 7. Sampling Results at Site 5Cleanup MW16 MW16Level a(1994)(1996)VillageWaterSupply(1997)MW28(1998)MW29(1998)MW30(1998)MW31(1998)MW32*(1998)VillageWaterSupply(1998)----8.79.7ND(4.1)ND(4.1)ND(4.1)----------0.87ND(10)--ND(5.2)ND(10)--ND(5.2)ND(10)--1.3ND(10)--ND(5.2)ND(10)------Groundwater (mg/L)DRO1.50.1050.58ND(0.1)ND(0.1)ND(0.1)1.90.11ND (0.1)to 0.07GRO1.3--TRPHNA0.4--ND(0.1)ND(0.25)--0.0261.1ND(0.1)ND(0.25)--0.054RROND(0.05)--0.124and0.103ND(0.04)ND(1.49)--ND(0.25)--ND(0.25)--ND(0.1)ND(0.25)--ND(0.05-0.1)ND(0.2-1.0)--Soil (mg/kg)DRO250GRORROTRPH30011,000NA1,160to1,800ND(5)-800 to1,430--Notes: ND non detect, NA not available, * MW32 is a replacement for MW16a18 AAC 75, Table B, Under 40 Inch Zone, Migration to Groundwater or Table C (August 8, 2003)Gambell Proposed PlanJuly 2004o Page 17A second phase of investigation was conducted from 1996-1998, due to concerns about possibleimpacts to the local water supply well. In 1996, groundwater from the two original monitoringwells (MW15 and MW16) was resampled and analyzed for DRO and VOCs. DRO was detectedin MW16. Sampling results are shown in Table 7. A geophysical survey also identified twoanomalies which indicated the presence of buried metallic debris at Site 5.In 1997, groundwater samples were collected from the Village water supply well before and afterthe excavation activities. Very low concentrations of DRO were detected in the water well;RRO, GRO, PCBs, and BTEX were not detected. Sampling results are shown in Table 7.In 1998, five additional monitoring wells and four soil borings were completed. Groundwaterand soil samples were collected and analyzed for DRO, GRO, RRO, BTEX, and PAHs. DROwas detected in two monitoring wells, MW31 and MW32 (a replacement for MW16). PAHs,RRO and BTEX were not detected in any of the groundwater samples. DRO was detected in soilat low levels in two locations, MW28 and MW29. Sampling results are shown in Table 7.Although DRO exceeded the ADEC groundwater cleanup level of 1.5 mg/L at MW31, there isno known source of contamination. No contamination was found above cleanup levels in the soilat MW31, or in either the soil or groundwater at an upgradient monitoring well (MW28) or theVillage Water Supply well. All the soil sampling results indicated contaminants were belowADEC regulatory levels.Monitoring well MW31 is located 185 feet cross-gradient (northwest) from the Village watersupply well, near the edge of the local aquifer. During monitoring well water measurementstaken in December 1998, the groundwater in this well was frozen, confirming its location at thefringe of the aquifer. The water depth at MW31 was 12 feet below ground surface, compared toFigure 4 – Groundwater contours and wells at Site 5¬N4.7 51994 GW contoursOct 1998 GW contoursAquifer boundary3 .4MW14ð3 .54.8MW30ð3.74.853. 63.94.0ArchaelogicalSite4.1A TVTraATVMW314.95MW28il3.8ð 4.9MW15ðTra ilðNewVillageWellToe ofSevuokukMountain³SB34##³ð MW32ðMW16³ SB33#SB36ðMW2950050 FeetGambell Proposed PlanSpringJuly 2004o Page 18about 18 feet below ground surface for the village water well intake, demonstrating that MW31is located in the shallower portion of the aquifer. Groundwater gradients measured on 5occasions during 1994 and 1998 all indicate the flow is northeast towards the Bering Sea. Figure4 shows the groundwater flow direction at Site 5.The DRO detected in soils at MW16 in the earliest phase of investigation has not beensubstantiated by subsequent sampling, and appears to be an isolated occurrence which is notimpacting the local water supply. The Village water supply well has been sampled on multipleoccasions and has not contained significant DRO contamination.Cleanup Objective: ADEC Table B soil cleanup levels based on the Migration to Groundwaterpathway, and the ADEC Table C groundwater cleanup levels.Preferred Alternative: No further action. However, one additional round of groundwatersampling will be conducted to confirm groundwater does not exceed ADEC Table C cleanuplevels. Existing monitoring wells at Site 5 will be sampled at upgradient and downgradientlocations to verify that diesel range organics are not impacting the Village water supply well.Site 6 – Military LandfillSite Description: Site 6 is located northof the Gambell High School and east ofthe new housing area. This landfill wasused to dispose of building materials,vehicles, machinery, drums of latrinewaste, and miscellaneous debris.Cleanup Actions to Date: In 1999, OSCIremoved exposed drums (7,897 pounds)and other metal debris (1,748 pounds).Debris excavated from Site 6 in 2003In 2003, NALEMP funded a removalaction at Site 6. Montgomery Watson Harza(MWH) excavated and removed buried debrisat the site, including empty 55-gallon drumsused to containerize latrine waste, engine parts,vehicle parts, marston matting, metal spikes,piping, tin cans, miscellaneous householdgarbage, and used oil filters. According to thefinal report (MWH, 2004), approximately 1,000drums and other debris, and 2.5 tons of fuelcontaminated soils were excavated. There wasno notable evidence of fuel contaminationassociated with the buried debris.Table 8. Sampling Results at Site 6ChemicalResults(1994)Groundwater (mg/L)DRO0.46 to 0.75Arsenic0.03 to 0.05Beryllium0.007Cadmium0.007 to 0.008Chromium0.107 to 0.364Chromium, dissolved0.006Lead0.12 to 0.172Lead, dissolved0.008Nickel0.08 to 0.153ScreeningLevel a1.50.050.0040.0050.10.0150.1Notes: a18AAC75, Table C (August 8, 2003)Investigation Summary: In 1994, a Phase I investigation was performed, including ageophysical survey to delineate the extent of buried debris, and collection of groundwatersamples. Five borings were drilled at Site 6; two borings encountered melted porewater whichGambell Proposed PlanJuly 2004o Page 19was sampled through the auger. The groundwater samples were analyzed for petroleumhydrocarbons (DRO, GRO, TRPH), VOCs, metals, sulfate, biological oxygen demand (BOD),coliform, and total suspended solids/total dissolved solids (TSS/TDS). Low levels of dieselrange organics and several metals were detected in the groundwater. Table 8 summarizes thesampling results. Metals were mostly detected in unfiltered water samples, and attributed tonaturally occurring levels of metals in soil particles suspended in the water column. Thesuprapermafrost groundwater at Site 6 is not considered a likely source of drinking water.After removing surfacedebris from the site in1999, OSCI collected aconfirmation soil samplefrom beneath theremoved drum stockpile.The soil contained nometals, fuels, solvents,PCBs, or pesticidesabove ADEC cleanuplevels.Table 9. Sampling Results at Site 6ChemicalCleanupConfirmationLevel aSample(1999)Soil (mg/kg)Arsenic5.55.3Antimony41Chromium3001.33Nickel2,000DRO12,250ND(9.35)ConfirmationSamples(2001)Soil Borings(2001)6-7.73.7-13.27.359120ND(5)-1,2003-6.3ND(0.5) -21Notes: ND non detect.a18 AAC 75, Table B, Under 40 Inch Zone, Ingestion (August 8, 2003)In 2001, a supplemental investigation was conducted to verify the OSCI sampling results and tofurther define the nature and extent of soil and groundwater contamination. Two surface soilsamples were collected from the approximate location of the 1999 confirmation sample, andanalyzed for GRO, DRO, RRO, and RCRA metals. Sampling results are shown in Table 9.Five soil borings were also advanced to frozen soil during the2001 field effort. Groundwater was not encountered in any ofthe soil borings. Soil samples were collected and analyzed forGRO, DRO, RRO, VOCs, and target analyte list (TAL)metals. Sampling results are summarized in Table 9. Thedetected arsenic concentrations exceeded the ADEC cleanuplevel. The average arsenic concentration was 7.5 mg/kg. Theobserved arsenic concentrations are consistent across many sitesin Gambell, and do not appear associated with past militaryactivity. No other analytes were detected in the soil samples atconcentrations exceeding the applicableADEC soil cleanup levels.target analyte list (TAL)metals: aluminum, antimony,arsenic, barium, beryllium,cadmium, calcium, chromium,cobalt, copper, iron, lead,magnesium, manganese,mercury, nickel, potassium,selenium, silver, sodium,thallium, vanadium, zincCleanup Objective: ADEC Table B soilcleanup levels based on the Ingestionpathway.Preferred Alternative: No furtheraction. The observed arsenicconcentrations in soil are consistent withbackground levels and do not appearassociated with a point source ofcontamination. Groundwater has notGambell Proposed PlanExcavation of drums at Site 6 in 2003July 2004o Page 20always been present at Site 6 and detections of metals appear related to suspended sedimentparticles. The major source of potential contamination has been removed at Site 6.Site 7 – Former Military Power FacilitySite Description: Site 7 is located north of the Gambell Municipal Building, and west of theGambell School. A military power facility was reportedly demolished and buried in thislocation. A military motor pool building was also believed to be located in this vicinity. The sitecontained a concrete pad and surface debris.Cleanup Actions to Date: During 2003, MWH removed the concrete pad, underlying supporttimbers, a buried 55-gallon drum, and 1 cubic yard of incidental contaminated soils through theNative American Lands Environmental Mitigation Program (NALEMP).Investigation Summary: A Phase Iremedial investigation was conductedduring 1994, which included a geophysicalsurvey to located possible buried debris, andcollection of soil and groundwater samples.In 1999, OCSI verified that no measurablequantities of surface debris remained at thesite. MWH collected additional soilsamples in 2001.The 1994 geophysical survey revealed nomajor anomalies indicative of large amountsof buried debris. Five soil borings wereSite 7 concrete pad and debris removed in 2003drilled to permafrost (6.5 to 15.0 feet belowground surface) and four were completed asmonitoring wells. Two surface soil samples were collected and analyzed for VOCs, GRO, DRO,TRPH, and priority pollutant metals. Subsurface soil samples were also analyzed for PCBs.Groundwater samples were analyzed for VOCs, GRO, DRO, TRPH, priority pollutant metals,and PCBs. Figure 5 depicts the Site 7 sampling locations.The 1994 investigation results indicated DRO and TRPH were present in surface and subsurfacesoil. The DRO concentrations did not exceed the ADEC cleanup level. There are no ADECcleanup levels for TRPH. Table 10 summarizes the sampling results. No other analytes werepresent at concentrations exceeding the ADEC cleanup levels.Three monitoring wells (MW24, MW25, MW27) were also installed into perched groundwaterpresent at Site 7, but they were essentially dry wells. A sufficient quantity of water could not bewithdrawn from MW27, and the sample was only submitted for analysis of VOCs, DRO, andpriority pollutant metals. Groundwater was not encountered in MW24, but a monitoring wellwas installed by drilling down into the ice to create a reservoir which would collect meltedgroundwater. A fourth well (MW26) was abandoned without collecting a groundwater sampledue to lack of water. Suprapermafrost groundwater was collected from the three wells. DRO,GRO and TRPH were detected in the groundwater. Benzene was also detected in monitoringwell MW24. The DRO and benzene results exceed the ADEC Table C groundwater cleanupGambell Proposed PlanJuly 2004o Page 21levels. Table 10summarizes the soiland groundwater resultscollected from the Site7 monitoring wells.Table 10. Sampling Results at Site 7 during 1994 investigationChemicalMW24MW25MW26MW27Soil (mg/kg)DRO20-941GRONDTRPH13-180BenzeneND (0.005)Groundwater (mg/L)DRO18.4GRO0.844TRPH4.2Benzene0.01920-271ND400-1,300ND (0.005)18-1,840ND115-13,000ND (0.005)NDNDND-162ND (0.005)ADECLevel a10,2501,400NA150Additional soil boringswere drilled in 2001 to19.4-1.181.5further investigate the--0.1031.3nature and extent of--1.1NAsoil andND (0.0005)-ND (0.0005)0.005suprapermafrostNotes: NA not available, ND not detected, -- not analyzed fora18AAC75 Table B, Under 40 Inch Zone, Ingestion, or Table C cleanup levels (August 8, 2003)groundwatercontamination, and to address continuing community concerns regarding Site 7. Three soilborings (SB7-18, SB7-19, SB7-20) were drilled to permafrost (6.2, 7.2 and 10.0 feet bgs); butgroundwater was not encountered in any of the soil borings. The soil samples were analyzedDRO, RRO, PCBs, and TAL metals. Sampling locations are shown on Figure 5.The 2001 investigation results showed DRO in one soil sample at a maximum concentration of710 mg/kg, which does not exceed the ADEC ingestion cleanup level of 10,200 mg/kg. Arsenicwas detected at concentrations ranging from 4.5 to 10.2 mg/kg, with an average concentration of7.8 mg/kg. Six of the eleven arsenic results exceeded the ADEC Table B arsenic ingestioncleanup level of 5.5 mg/kg. Although the detected arsenic concentrations exceed the ADECcleanup level, the levels are consistent across many sites in Gambell, and do not appearassociated with past military activity. PCBs were not detected in any Site 7 samples. No other³Figure 5 – Site 7 Sampling LocationsSB27-1SB27-2³SB27-3³HouseQ. BuildingMetal FreightContainers (former)Site 7#SS41#SS40MW26#³ SB7-18ðSB17³MW24Concrete Slab(removed 2003)07SL001 # ð07SL002 # # # 07SL00407SL003MW25³ð SB7-20##07SL005SB7-19#³FuelPipelineMW27ðGambell Proposed PlanJuly 2004o Page 22analytes were detected in the soil samples at concentrations exceeding the cleanup levels.The supplemental investigation demonstrated that the groundwater at Site 7 is ephemeral, andsoil contamination is below cleanup levels. The risk of contaminant migration east towards theaquifer located at the base of Sevuokuk Mountain is extremely low. MWH abandonedmonitoring well MW24 during the 2003 NALEMP removal action. It is highly unlikely theother two monitoring wells (MW25, MW27) are still functional.After the 2003 removal action, MWH collected five confirmation soil samples from the edges ofthe concrete pad excavation and one sample from beneath the excavated drum. The five samplesnear the concrete pad containedarsenic levels ranging from 4.2 to34.9 mg/kg, which exceeds theADEC ingestion cleanup level of5.5 mg/kg, and may correspond toleached preservative from thetreated timbers used as a formsurrounding the concrete pad.One sample also contained DROat 570 mg/kg, which does notexceed the ADEC ingestioncleanup level of 10,200 mg/kg.This fuel may correspond toleakage from a community fuelpipeline present at edge of pad.Cleanup Objective: ADEC TableB soil cleanup levels based on theIngestion pathway.Removal of concrete pad at Site 7 in 2003Preferred Alternative: Excavate arsenic-contaminated soil from around the edges of the formerconcrete pad location. Dispose of soil at an off-site landfill. Collect confirmation samples andanalyze for arsenic. This alternative is protective of human health and the environment becauseit permanently reduces the risk posed by the soil containing elevated arsenic. The no furtheraction alternative was rejected because it would not meet established regulatory criteria, orreduce the toxicity, mobility, or volume of contaminated soil. Implementation of institutionalcontrols or access restrictions are infeasible for the site because it is located in a high-traffic,residential area of town.Sites 8A, 8B, 8C, 8D – West Beach AreaSite Description: Site 8 includes the area surrounding the airstrip from west beach (north of theairfield), east to the western edge of Troutman Lake, and south to the northern shore of NorthNayvaghat Lakes. Marston matting (8A) is located along the eastern side of the airstrip. Buriedmiscellaneous metallic debris (8B) has been reported south of the old village area, includingnumerous 55-gallon drums and a Jeep. A Navy Landfill (8C) is located northwest of the formerCivil Aeronautics Administration (CAA) housing area and south of the village landfill. TheNavy reportedly constructed this landfill during their utilization of the former CAA housing area.Gambell Proposed PlanJuly 2004o Page 23The Navy landfill may have asbestos-containing materials (ACM). Small-arms ammunitionrounds (0.30-caliber) are also located along the beach (8D) southwest of Troutman Lake. AnArmy landfill was also reportedly located northwest of the Nayvaghat Lakes area.Cleanup Actions to Date: In 1999, Oil Spill Consultants, Inc. removed surface debris from thearea, including scattered metal, small quantities of wood and concrete, and an exposed layer ofmarston matting approximately 30 feet wide and 4,500 feet long along the eastern side of theairstrip. OSCI did not complete the planned removal of the marston matting because buriedelectrical lines interfered with the excavation. Approximately 1,820 feet of metal marstonlanding mat remains at Site 8A. Earth Tech, Inc. recovered approximately 800 small armsrounds from Site 8D in July 2000, and shipped the material off-site to a facility in Colfax,Louisiana for disposal. Additional rounds remain in about 100 cubic yards of soil.Investigation Summary: In 1994, a remedial investigation was completed at Site 8 whichincluded a geophysical survey to determine the extent of buried debris at the reported Armylandfill, installation of one monitoring well, and collection of soil and groundwater samples.The 1994 investigation results indicated that all detected analytes in soil/groundwater werebelow ADEC cleanup levels. The geophysical survey results also indicated no significantanomalies, confirming the reportedMarston matting at Site 8AArmy landfill was not present.In 2000, Earth Tech, Inc. surveyed Site8D using metal detectors to locatepossible ordnance and explosivematerials. Highly weathered small armsrounds were documented in a beachburial pit southwest of Troutman Lake.Cleanup Objective: ADEC Table B soilcleanup levels based on the Ingestionpathway.Preferred Alternative: No further action at areas 8B and 8C. These sites also meet the morestringent ADEC soil cleanup levels based on the Migration to Groundwater pathway. The burieddebris is not eligible for further action under FUDS. Remove exposed marston matting along theeast side of the runway (8A) and remove small caliber ammunition from the beach dump sitesouth of the airport runway (8D). Transport the debris to an off-site landfill or recycling facility.This alternative will involve sifting and/or hand-picking the ammunition rounds from thegravelly soils, and consolidating the marston matting. The Alaska Department of Transportationand Public Facilities will be coordinated with during removal of the exposed debris to ensureairport operations are not disrupted. This alternative effectively reduces the long-term physicalhazard posed by the debris.Other alternatives were considered and rejected during the feasibility study phase. The exposeddebris would continue to pose a physical hazard to local residents if no further action is taken.Site controls such as installation of fencing near the runway at Site 8A would requirecoordination with and approval from the landowner, the Alaska Department of TransportationGambell Proposed PlanJuly 2004o Page 24and Public Facilities. Construction of fencing may adversely affect maintenance of airportlighting/ navigation aids or snow removal activities. Installation of fencing around Site 8Dwould also impede snow machine travel during the winter, when obstacles are difficult toobserve in poor weather conditions. Thus, access restrictions were not retained for furtherevaluation.Site 9 – Asphalt Barrel CacheSite Description: This site is located on the east side of the local airport runway. Drums leakingtar were observed in two areas. A debris inventory prepared by Montgomery Watson in 1997indicated drums containing asphalt (6,200 estimated pounds) and empty drums (900 pounds)were located within Site 8, which includes the area referred to as Site 9. The asphalt drums wereinitially attributed to non-military activities during the Phase I investigation and not investigatedfurther.Cleanup Actions to Date: Oil Spill Consultants overpacked and removed nine drums of asphalt(4,458 pounds) and associated stained soils (4,790 pounds) from east of the runway during the1999 removal action activities. All empty drums were also removed.Investigation Summary: OSCI collected one confirmation soil sample after removing theasphalt drums and stained soil. The sample was analyzed for petroleum hydrocarbons (DRO,GRO, RRO), VOCs, SVOCs, PCBs, pesticides, and metals. The results indicated that allanalytes were below the cleanup levels or not detected.In 2001, two additional samples were collected to verify the 1999 results. The samples wereanalyzed for petroleum hydrocarbons (DRO, GRO, RRO), and RCRA metals. Arsenic wasdetected at concentrations of 5.3 and 6.8 mg/kg, which exceeds the ADEC cleanup level of 5.5mg/kg. However, the levels are consistent across many sites in Gambell, and do not appearassociated with past military activity. All other analytes were below the cleanup levels or notdetected.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. All hazardous debris and contaminated soil have beenremoved from the site. Site 9 also meets the more stringent ADEC cleanup levels based on theMigration to Groundwater pathway.Site 10 – Sevoukuk Mountain TrailSite Description: A trail system originates at the southeast end of Troutman Lake and separatesinto individual trails to the north, south, and east. Two trails lead to the top of SevuokukMountain. Empty 55-gallon drums located approximately 250 feet apart marked the trails.Other debris at the site included marston matting and weasel tracks.Cleanup Actions to Date: In 1999, Oil Spill Consultants, Inc., removed all the scattered drums(12,516 pounds), miscellaneous metallic debris (1,388 pounds), and a small amount (540pounds) of stained soils.Gambell Proposed PlanJuly 2004o Page 25Investigation Summary: During the 1994 remedial investigation, no staining or stressedvegetation was observed and the drums were either empty or contained gravel.Preferred Alternative: No further action. All hazardous materials and debris have beenremoved from the site.Site 11 – Communications Cable RouteSite Description: Site 11 contained a sonar cable going up Sevuokuk Mountain, abandonedcable spools, and a remnant of braided metal cable on top of the mountain. During the 1994investigation, the only evidence of sonar cables were some cable spools near Site 4D.Cleanup Actions to Date: OSCI removed the debris at Site 4D during the 1999 removal action.Preferred Alternative: No further action. The remaining debris is not eligible for further actionunder FUDS.Site 12 – North Nayvaghat Lakes Disposal SiteSite Description: Site 12 is located north of Nayvaghat Lakes on the southwest side of an allterrain vehicle (ATV) trail. The site is divided into a north and a south area (see Figure 7). Thenorth area contained approximately 120 drums, battery remnants, and household refuse. Thesouth area contained approximately 50 drums, including 18 drums full of garbage.Cleanup Actions to Date: In 1999,OSCI removed contaminated soil anddebris from the site including drums,dried paint, and batteries. OSCIremoved 798 pounds of metaldebris/drums, 8,702 pounds ofhazardous and toxic debris, and 7,237pounds of stained soil.Figure 7 – Site 12 and vicinityTroutman LakeUnnamed PondInvestigation Summary: The site wasinvestigated during the 1994 Phase Iremedial investigation. OSCIcollected soil confirmation samplesfollowing the removal activities.Additional confirmation samples werecollected during the 2001supplemental investigation.Site 12North AreaSite 8DSite 12South AreaNNorth NayvaghatLakesSamples collected in 1994 includedone surface water sample from NorthNayvaghat Lake, two groundwater,three surface soil samples, and twosubsurface soil samples. The soil samples were analyzed for VOCs, GRO, DRO, TRPH, prioritypollutant metals, and PCBs. Groundwater and surface water samples were analyzed for VOCs,500Gambell Proposed PlanJuly 200405001000 Feeto Page 26GRO, DRO, TRPH, PCBs, and priority pollutant metals. The concentrations of metals detectedin the soil samples were below background. Arsenic concentrations ranged from 4 to 10 mg/kg.The arsenic levels are consistent across many sites in Gambell, and do not appear associated withpast military activity. No other analytes were detected in the soil samples. DRO and metalswere detected at low levels in surface water and groundwater, but did not exceed backgroundlevels or the ADEC Table C cleanup levels. Background levels for groundwater and surfacewater were determined from a sample taken from MW-14 located at the base of SevoukukMountain.Confirmation samples were collected aftercompleting the removal actions. Arsenic,cadmium, lead, and DRO were detected in soilat concentrations exceeding the ADEC cleanuplevels. The sampling results are summarized inTable 11.Table 11. Confirmation Sampling Results at Site 12ChemicalCleanupResultsResultsLevel a(1999)(2001)Soil (mg/kg)Arsenic23–66 – 9.4Cadmium50.18 - 142ND(0.2) – 1.6Chromium262.6 - 205.7 – 162Lead40012.4 - 5627 – 1,530DRO250463ND(5) – 46In 2001, supplemental RI fieldwork wasNotes: ND non detecta18AAC75 Table B, Under 40 Inch Zone, migration to groundwatercompleted at Site 12 to verify the previouspathway (August 8, 2003)confirmation sampling results. Soil sampleswere collected and analyzed for petroleum hydrocarbons (GRO, DRO, RRO), and RCRA metals.Arsenic, chromium, and lead exceeded the ADEC cleanup levels. DRO and cadmium were notdetected at concentrations exceeding the cleanup levels. The sampling results are summarized inTable 11. No other analytes were detected at concentrations exceeding the ADEC cleanuplevels. The arsenic levels at Site 12 are consistent across many sites in Gambell, and do notappear associated with past military activity.Cleanup Objective: The cleanup levels selected for Site 12 are the ADEC Table B soil cleanuplevels, based on the Migration to Groundwater pathway. Site 12 is located between Troutmanand North Nayvaghat Lakes, and contaminants have the potential to impact subsurfacegroundwater or surface waters.Preferred Alternative: Excavate lead-contaminated soil, transport off-site for disposal at apermitted landfill. Since elevated levels of chromium and cadmium were detected in the samevicinity as the lead-contaminated soil, these contaminants will also be removed under thisalternative. Excavation and off-site disposal of soil will permanently reduce the potential riskposed by contaminated soils at Site 12.The no further action alternative was rejected because it would not reduce the risk associatedwith the lead-contaminated soil. There would be no reduction in the toxicity, mobility, orvolume of contaminated soil. This alternative would not meet established regulatory criteria.Implementation of institutional controls or access restrictions were determined to be infeasiblefor the site. In-situ treatment of the contaminated soils was also considered, but ultimatelyrejected due to challenges in implementation at a remote site and additional testing requirements.Treatment of the soil on-site may reduce the mobility and toxicity of the lead, but it will notreduce the overall volume of lead contaminated soil.Gambell Proposed PlanJuly 2004o Page 27Site 13 – Former Radar Power StationSite Description: Site 13 is located east of the pond between Troutman and North NayvaghatLakes. The radar power station consisted of two wooden Quonset huts, one long woodenbuilding, and several 150 foot towers that were reportedly demolished and buried on-site.Stained soils and miscellaneous surface debris such as steel wire, pipes, and marston mattingwere observed at the site.Cleanup Actions to Date: In 1999, OSCI removed 343 pounds of miscellaneous metal debrisfrom surface areas at Site 13.Investigation Summary: Site 13 was investigated during the 1994 remedial investigation,including a geophysical survey to determine the extent of buried debris, installation of 3monitoring wells, and collection of soil, surface water and groundwater samples.The geophysical survey revealed strong anomalies around two mounds and scattered surfacedebris which are probably related to significant amounts of buried material. Subsurface soilsamples were also collected and analyzed for VOCs, petroleum hydrocarbons (GRO, DRO,TRPH), priority pollutant metals, and PCBs. Surface soil samples were collected and analyzedfor TRPH, PCBs, and priority pollutant metals. No analytes, except arsenic, were detected atconcentrations exceeding cleanup levels. Arsenic concentrations ranged from 2 to 6 mg/kg, withan average concentration (95%UCL) of 4.5 mg/kg, compared to the ADEC Table B ingestioncleanup level of 5.5 mg/kg.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. The buried debris is not eligible for further actionunder FUDS. Site 13 also meets the more stringent ADEC cleanup levels based on theMigration to Groundwater pathway.Site 14 – Navy Plane Crash SiteSite Description: This site is located approximately 7 miles south of the Village of Gambell. ANavy reconnaissance plane which crashed in 1955 remains on the tundra, with debris located inthe area immediately surrounding the plane. There were no apparent stains or any stressedvegetation at the site.Preferred Alternative: No further action. The debris is not eligible for further action under FUDS.Site 15 – Troutman Lake Disposal SiteSite Description: This site was reported to contain submerged ordnance at the north end ofTroutman Lake.Investigation Summary: During 2000 and 2001, Troutman Lake was investigated usinggeophysical surveying techniques. The entire lake bottom was mapped along a series of transectlines, to detect underwater anomalies representative of piles of steel ammunition boxes. Metallicanomalies detected by the equipment were then further investigated using ice augers, depthGambell Proposed PlanJuly 2004o Page 28sounding equipment, poles, and an underwater video camera to determine the source of the metalsignal. An open water investigation was also conducted to verify the anomaly source usingdredging anchors, depth-sounding leads, and an underwater camera. Anomaly locations within20 feet of the lakeshore were verified by visual inspection. The source of the magneticanomalies ranged from runway matting and 55-gallon drums, to geologic features such as iron orother mineral deposits. No evidence of ordnance or large piles of ammunition boxes wasdiscovered in Troutman Lake. Additional details regarding the ordnance investigation can befound in the report Final Engineering Evaluation/Cost Analysis (Earth Tech Inc., 2002).Preferred Alternative: No further action. The remaining underwater debris (miscellaneousmetal debris) is not eligible for further action under FUDS.Site 16 – Gambell Municipal Building SiteSite Description: This site consisted of a 35 by 55-foot area of stained gravel, locatedimmediately west of the Municipal Building. The origin of the stain is unknown, and staining ismost visible after a rainfall event.Investigation Summary: Investigations were conducted during the 1994 Phase I remedialinvestigation, including a geophysical survey and collection of surface and subsurface soilsamples. Additional soil samples were collected during the 2001 supplemental investigation.The 1994 geophysical survey results revealed four small anomalies which may be related toburied materials. Surface soil samples were also collected and analyzed for petroleumhydrocarbons (DRO, GRO, TRPH), and priority pollutant metals. Subsurface soil samples wereanalyzed for VOCs, GRO, DRO, TRPH, PCBs, and priority pollutant metals. Groundwater wasnot encountered in the soil borings. Arsenic results ranged from 2 to 7 mg/kg, with an averageconcentration (95% UCL) of 5.4 mg/kg. Only 1 out of 7 samples exceeded the ADEC Table Bingestion cleanup level of 5.5 mg/kg. No other contaminants were identified at Site 16.In 2001, four additional soil borings were drilled at the site based on community concerns. Thesamples were analyzed for petroleum hydrocarbons (DRO, GRO, RRO), VOCs or BTEX, andTAL metals. Fuels were not detected in any sample. Arsenic concentrations ranged from 3.6 to9.8 mg/kg. Only 1 sample exceeded the ADEC Table B ingestion cleanup level of 5.5 mg/kg.The arsenic levels are consistent across many sites in Gambell, and do not appear associated withpast military activity.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. The buried debris is not eligible for further actionunder FUDS. Site 16 also meets the more stringent ADEC cleanup levels based on theMigration to Groundwater pathway.Site 17 – Army LandfillsSite Description: The Army Landfills are located between the North Beach and Site 6 MilitaryLandfill, which is north of the Gambell School and Municipal Building. The two landfillsGambell Proposed PlanJuly 2004o Page 29reportedly contained buried debris and/or trash, as well as exposed surface debris such as drums,marston matting, and scrap metal.Cleanup Actions to Date: Exposed miscellaneous surface debris, including nodwell tracks,marston matting, steel cable and scrap metal, was removed by Oil Spill Consultants during the1999 removal action. The actual tonnage of debris removed was combined with Site 6 for a totalof 1,748 pounds.Investigation Summary: During the 1994 Phase I remedial investigation, a geophysical survey,installation of monitoring wells, and collection of soil and groundwater samples was completed.The 1994 geophysical survey results indicated the potential for buried debris associated with thereported landfills. In addition, five soil borings were completed to permafrost (7.5 to 10.5 feet).Monitoring wells were not installed at the site because well completion was impractical. Meltedporewater samples were collected through the auger and submitted for analysis of VOCs, PCBs,petroleum hydrocarbons (GRO, DRO, TRPH), and priority pollutant metals. No contaminantswere detected in the groundwater samples at concentration above ADEC Table C cleanup levels.Arsenic ranged from 2 to 6 mg/kg in soil, compared to the ADEC ingestion cleanup level of 5.5mg/kg. Only 1 sample out of 13 exceeded the cleanup level. The arsenic levels are consistentacross many sites in Gambell, and do not appear associated with past military activity. No otheranalytes were detected in soil above screening levels.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. The remaining buried debris is not eligible for furtheraction under FUDS. Site 17 also meets the more stringent ADEC cleanup levels based on theMigration to Groundwater pathway.Site 18 – Former Main CampSite Description: This site is located at the northeast end of Troutman lake, between the currentMunicipal Building and east of the Gambell School.Investigation Summary: Investigations completed at Site 18 in 1994 include a geophysicalsurvey to determine the presence of buried debris, and collection of subsurface soil andgroundwater samples. A white powdery material was also observed in a berm which bordersTroutman Lake, and was determined to be inert, diatomaceous earth previously used for waterfiltration by the military (see Site 19).A geophysical survey completed in 1994 showed a linear anomaly in the center of the surveygrid, (between the high school and the washeteria). This feature was thought to represent buriedwater delivery lines for the existing Power Plant. One soil boring was drilled south of theanomaly due to the reported burial of discarded underground storage tanks in the vicinity.Subsurface soil samples and melted porewater were collected and analyzed for VOCs, petroleumhydrocarbons (DRO, GRO, TRPH), priority pollutant metals, and PCBs. No analytes weredetected above screening levels. Arsenic concentrations in soil ranged from 2 to 5 mg/kg, anddid not exceed the ADEC Table B Ingestion cleanup level.Gambell Proposed PlanJuly 2004o Page 30During the 2001 investigation, further sampling was conducted at Site 18 based on communityconcerns. One soil boring was placed adjacent to the north fence of the Municipal WaterTreatment/ Washeteria Building. The soil boring was advanced to 17.5 feet below groundsurface, and two soil samples were collected near the bottom of the boring. The samples wereanalyzed for petroleum hydrocarbons (DRO, GRO, RRO), VOCs, and TAL metals. DRO wasdetected at concentrations ranging from 54 to 640 mg/kg in subsurface soil, which does notexceed the ADEC cleanup level of 10,250 mg/kg. Arsenic was detected at concentrationsranging from 5.6 to 5.9 mg/kg, which slightly exceeds the ADEC cleanup level of 5.5 mg/kg.Arsenic levels are consistent across many sites in Gambell, and do not appear associated withpast military activity. No other analytes were detected above screening levels. One well pointwas also installed, and free product was observed. The free product recovered from the wellpoint appeared clear and clean, and had the strong odor of fresh fuel, features not typical ofdegraded fuels from previous military activities. The free product (water) was not sampled.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. The buried debris is not eligible for further actionunder FUDS.Site 19 – Diatomaceous EarthSite Description: Site 19 was identified as a separate area of concern by the Native Village ofGambell under the NALEMP program. This area coincides with the description of Site 18presented above. Diatomaceous earth is an inert material which does not pose a chemicalhazard, and thus cannot be addressed further under the FUDS program.Preferred Alternative: No further action.Schoolyard after rubble removed in 2003Site 20 – SchoolyardSite Description: Site 20 is located north ofthe former Main Camp (Site 18) near thecurrent Gambell School. The schoolyardcontained two rubble piles that consistedprimarily of concrete and rebar, plus apartially exposed concrete slab. The pilespresented a physical hazard to local residentssuch as children attending school, ATV andsnowmachine traffic.Cleanup Actions to Date: The rubble pilesand concrete pad were removed during August 2003 under the NALEMP program.Preferred Alternative: No further action.Gambell Proposed PlanJuly 2004o Page 31Site 21 – Toe of Sevuokuk MountainSite Description: This area, located at the base of Sevuokuk Mountain and southwest of Site 5,is thought to contain buried miscellaneous wire and metallic debris from military activities.Preferred Alternative: No further action. The buried debris is not eligible for further actionunder FUDS.Site 22 – Former CAA HousingSite Description: Former Civil Aeronautical Administration (CAA) Housing units are locatednear the northeast edge of the Old Gambell section of the village. The CAA housing areaconsists of six homes and one lodge originally built as a weather data collection facility to helpguide Russian pilots during World War II. The Navy and Army also reportedly used the housingarea during the Cold War era during their efforts to lay submarine detection cables off the coastof St. Lawrence Island. This site was identified as a concern under the NALEMP program dueto the possibility that asbestos-containing materials may be present in the structures.Preferred Alternative: No further action. The buildings are presently occupied and/or owned bylocal residents, thus they do not qualify for further action under FUDS due to beneficial reuse.Site 23 – Debris from High School ConstructionSite Description: This site was identified by local residents as a concern in the Strategic ProjectImplementation Plan (SPIP) produced for the NALEMP program. The area is located due east ofthe Gambell landfill and consists of metallic debris that was originally unearthed during theconstruction of the Gambell High School. The City of Gambell moved the excavated debris tothe local landfill for reburial. Removal actions undertaken by current landowners are not eligiblefor reimbursement or further action under FUDS.Preferred Alternative: No further action. The buried debris is not eligible for further actionunder FUDS.Site 24 – South of Municipal BuildingSite Description: This area is located south of the Municipal Building along the northern shoreof Troutman Lake.Investigation Summary: A geophysical survey of the site was conducted in 2000, andsubsurface anomalies consistent with metallic debris were found. During the 2001 supplementalremedial investigation, one soil boring was drilled to frozen soil. Two soil samples werecollected and analyzed for petroleum hydrocarbons (DRO, GRO, RRO), VOCs, and TAL metals.The results of the 2001 investigation showed that the soil samples contained arsenic atconcentrations of 5.7 and 6.3 mg/kg. The arsenic levels are consistent across many sites inGambell, and do not appear associated with past military activity. Fuels were not detected in thesoil samples. No other analytes were detected at concentrations exceeding the screening levels.Gambell Proposed PlanJuly 2004o Page 32Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. The buried debris is not eligible for further actionunder FUDS. Site 24 also meets the more stringent ADEC cleanup levels based on theMigration to Groundwater pathway.Site 25A – Village of Gambell South Housing UnitsSite Description: Local residents identified the south housing units site as an area that may becontaminated by fuel-related products of military origin. During construction work performed in1997 by Alaska Village Safe Water, oily soils were encountered at the permafrost interface.Residents are concerned that the military may have dumped barrels of oil directly on the groundin this vicinity.Investigation Summary: During the 2001 supplemental investigation, six soil borings weredrilled to permafrost, based on the locations of buried utilities, depressions, trenches, anddisturbed ground identified by local residents and historical aerial photographs.Soil samples were collected and analyzed for petroleum hydrocarbons (DRO, GRO, RRO), andBTEX. A subset of samples were also analyzed for VOCs and TAL metals. The results werecompared to the ADEC Table B cleanup levels based on the migration to groundwater pathway.Fuels, BTEX and VOCs were not detected above cleanup levels in any sample. Arsenic wasdetected at concentrations from 2.2 to 19.2 mg/kg. Two of the three samples exceeded theADEC cleanup level of 5.5 mg/kg. An analysis of the entire dataset from 2001 shows an averageconcentration (95% UCL) for arsenic of 7 mg/kg. The arsenic levels are consistent across manysites in Gambell, and do not appear associated with past military activity.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. The observed arsenic concentrations are comparableto background levels elsewhere on St. Lawrence Island, and do not appear associated with apoint source of contamination. Site 25A also meets the more stringent ADEC cleanup levelsbased on the Migration to Groundwater pathway.Site 25B – Low Drainage Area Southwest of ArmorySite Description: Local residents identified this site during the 2001 supplemental investigationas an area where contaminants may migrate and accumulate. The site is located west of theSivuqaq Lodge, southeast of the Gambell store and fuel storage tanks, and near a local churchand Army Guard building.Investigation Summary: Two soil borings were drilled to frozen soil (depth of 11 and 12 feet)to identify potential contamination. Soil samples were collected and analyzed for petroleumhydrocarbons (DRO, GRO, RRO), BTEX, and PCBs.The soil sampling results were compared with the ADEC Table B cleanup levels, based on themigration to groundwater pathway. No analytes were detected at concentrations exceeding thescreening levels.Gambell Proposed PlanJuly 2004o Page 33Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. Site 25B also meets the more stringent ADEC cleanuplevels based on the Migration to Groundwater pathway.Site 26 – Possible Debris Burial SiteSite Description: Site 26 was identified from a 1953 aerial photograph as a possible debrisburial feature. The site is located east of the Gambell School near the Former Main Camp (Site18). Local residents reported finding metal debris, machinery, oily debris, and transformers inthis vicinity.Investigation Summary: During the 2001 supplemental remedial investigation, two soil boringswere drilled to frozen soil. Soil samples were collected and analyzed for petroleumhydrocarbons (DRO, GRO, RRO), VOCs, and TAL metals.The results of the 2001 investigation showed arsenic at concentrations ranging from 3.6 to 7.7mg/kg in surface and subsurface soils. One out of four samples exceeded the ADEC Table Bingestion cleanup level of 5.5 mg/kg. The arsenic levels are consistent across many sites inGambell, and do not appear associated with past military activity. No other analytes weredetected above cleanup levels.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. The observed arsenic concentrations are comparableto background levels elsewhere on St. Lawrence Island, and do not appear associated with apoint source of contamination. Site 26 also meets the more stringent ADEC cleanup levels basedon the Migration to Groundwater pathway.Site 27 – Drum Storage AreaSite Description: Analysis of an aerial photograph from 1955 indicated this location was ahistorical drum storage area. The community was also concerned about an area of rust-stainedsoil at this site. The site is located north of the former military power facility (Site 7), within thenew housing area. The drums stored at this site have been removed.Investigation Summary: During the 2001 supplemental remedial investigation, four soil boringswere drilled to frozen soil to determine if contamination was present. Samples were collectedand analyzed for petroleum hydrocarbons (DRO, GRO, RRO), VOCs, PCBs, and TAL metals.The 2001 investigation results were compared with the ADEC Table B cleanup levels, based onthe migration to groundwater pathway. Arsenic concentrations ranged from 5.4 to 16.9 mg/kg.The arsenic levels are consistent across many sites in Gambell, and do not appear associated withpast military activity. No other analytes were detected in the soil samples at concentrationsabove screening levels. PCBs were not detected.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Gambell Proposed PlanJuly 2004o Page 34Preferred Alternative: No further action. The observed arsenic concentrations are comparableto background levels and do not appear associated with a point source of contamination. Site 27also meets the more stringent ADEC cleanup levels based on the Migration to Groundwaterpathway.Site 28 – Disturbed GroundSite Description: Site 28 was identified from a 1972 aerial photograph as a disturbed area. Thissite is located south of Troutman Lake and west of an unnamed pond. The U.S. Army reportedlyleased this area from January 1955 to May 1958; however, the Army’s use of the land isunknown.Investigation Summary: During the 2001 supplemental investigation, two soil borings wereadvanced to frozen soil to determine if contamination was present. Subsurface soil samples werecollected and analyzed for petroleum hydrocarbons (DRO, GRO, RRO), VOCs, and TAL metalsThe sampling results were compared with the ADEC Table B cleanup levels, based on themigration to groundwater pathway. Arsenic concentrations ranged from 5.5 to 10 mg/kg. Thearsenic levels are consistent across many sites in Gambell, and do not appear associated with pastmilitary activity. No other analytes were detected in the soil samples at concentrations abovescreening levels.Cleanup Objective: ADEC Table B soil cleanup levels based on the Ingestion pathway.Preferred Alternative: No further action. The observed arsenic concentrations are comparableto background levels and do not appear associated with a point source of contamination. Site 28also meets the more stringent ADEC cleanup levels based on the Migration to Groundwaterpathway.Gambell Proposed PlanJuly 2004o Page 35SUMMARY OF PREFERRED REMEDIAL ALTERNATIVESThe preferred remedial alternatives for the 38 sites discussed in this Proposed Plan are:§§§§§No Further Action at Sites 1A, 1B, 1C, 2, 3, 4A, 4B, 4C, 4D, 4E, 5, 6, 8B, 8C, 9, 10, 11,13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25A, 25B, 26, 27, 28Excavate and off-site disposal of arsenic-contaminated soil at Site 7Removal and off-site disposal of exposed marston matting at Site 8AExcavate and off-site disposal of small arms ammunition at Site 8DExcavate and off-site disposal of lead-contaminated soil at Site 12Gambell Proposed PlanJuly 2004o Page 36Additional InformationAll supporting documents and detailed historical information can be found in the InformationRepositories located at:Sivuqaq Corporation Building (Lodge)P.O. Box 101Gambell, Alaska 99742Phone: (907) 985-5826Hours: Monday – Friday 9:00 a.m. to 5:00 p.m.National Parks Service179 Front Street, Suite 121Nome, Alaska 99762Phone: (907) 443-6101Hours: Monday – Friday 8:00 a.m. to 5:00 p.m.Savoonga IRA BuildingP.O. Box 120Savoonga, Alaska 99769Phone: (907) 984-6414Hours: Monday – Friday 9:00 a.m. to 5:00 p.m.Alaska Resource Library and InformationServices (ARLIS)3150 C Street, Suite 100Anchorage, Alaska 99503Phone: (907) 271-4560Hours: Monday – Friday 8:00 a.m. to 5:00 p.m.If you have questions about the information provided in this Proposed Plan, please contact:Mr. Carey CossaboomProject ManagerU.S. Army Corps of Engineers, Alaska DistrictP.O. Box 6898 (PM-C-FUDS)Elmendorf AFB, AK 99506-6898Phone: (907) 753-2689Fax: (907) 753-5626Email: Carey.C.Cossaboom@poa02.usace.army.milCommunity ParticipationYou are encouraged to provide comments on any of the alternatives presented in this ProposedPlan for the Gambell FUDS. A final decision on the alternatives for each of these sites will notbe made until public comments are considered. The USACE will prepare a written response toall significant comments and any new data submitted in reference to this Proposed Plan. Asummary of these responses will accompany the Decision Document and will be made availablein the Administrative Record and Information Repositories. Your comments can presentedeither in writing or at the following scheduled public meeting:Date: Wednesday, July 21, 2004Time: 7 pmPlace: Gambell, AlaskaThe public comment period ends August 23, 2004. A pre-addressed comment form is included.Gambell Proposed PlanJuly 2004o Page 37Glossary of TermsAdministrative Record – A collection of historical documentssuch as reports, studies, and maps which support the final cleanupdecision for a site. This file is available for public review.Aquifer – Rock or sediment in a formation that is capable oftransmitting significant quantities of water. Common aquifermaterial includes mixtures of sand, silt, and gravel.Alaska Department of Environmental Conservation (ADEC) –The lead state regulatory agency responsible for protecting publichealth, safety, and welfare, and the environment from adverseeffects of environmental contamination.Applicable or Relevant and Appropriate Requirements(ARARs) – Laws and regulations that establish cleanup levels forsites with contamination. ARARs include cleanup standards,standards of control, and other environmental protection criteria asspecified under federal and state statutes and regulations. ARARsmust be met (or a waiver approved) at a site to comply withCERCLA.BNAs – Base, neutral, and acid compounds (includes PAHs).Benzene – A colorless, volatile, inflammable, carcinogenic liquid(C6H6) used in a variety of chemical products, including motorfuel. Compounds containing benzene are called aromaticcompounds.Benzene, toluene, ethylbenzene, and xylene (BTEX) – Volatileorganic chemicals (aromatic compounds) that are constituents ofpetroleumBGS – Below ground surface.Cleanup level – The concentration of a hazardous substance thatmay be present within a specified medium (i.e., soil, groundwater,or surface water) without posing an unacceptable risk to humanhealth, safety, welfare, or the environment. ADEC providestabulated cleanup levels in 18 AAC 75 that are applicable tocontaminated soil and groundwater sites in Alaska.Comprehensive Environmental Response, Compensation, andLiability Act (CERCLA) – The federal law, also known asSuperfund, that guides cleanup of hazardous waste sites.Decision Document – Identifies the selected remedy for a site, therationale for its selection, and includes responses to publiccomments received on the Proposed Plan.Diesel-range organics (DRO) – A mixture of organic compoundsfound in diesel fuel, jet fuel, and heating oil. Polynuclear aromatichydrocarbons (PAHs), such as naphthalene, are included in thisrange. DRO are generally less volatile and less soluble than GRO.Formerly Used Defense Site (FUDS) – Properties that wereformerly used by the Department of DefenseGasoline-range organics (GRO) – A mixture of organiccompounds found in gasoline.Geophysical Survey – A method used to delineate undergroundfeatures such as metallic debris.Hazardous substance - A chemical that presents an imminent andsubstantial danger to the public health or welfare if it is released tothe atmosphere, surface water, groundwater, or land surface.Regulatory definitions can be found in CERCLA § 101(14) and102 and in the NCP40 CFR § 300.5.Information Repository – A publicly accessible location wherehistorical documents are stored.Institutional Controls (ICs) – Any type of physical, legal, oradministrative mechanism to restrict the use of, or limit access to,real property to prevent exposure to contaminants abovepermissible levels. The intent of the controls is to protect humanhealth, the environment, and the integrity of an engineeringremedy by limiting the activities that may occur at a particular site.Common examples of ICs include physical barriers to a site (e.g.,fences and signs) and land use restrictions (e.g., restricting theinstallation of drinking water wells).Method 2 Cleanup Levels – In 18 AAC 75, the State of Alaskaprovides four possible methods for determining soil cleanup levels.Method 2 utilizes tabulated cleanup levels (Table B1 and Table B2for soil and Table C for groundwater) that must be met for siteclosure. Meeting the tabulated cleanup levels is considered to beprotective of human health.Milligram per kilogram (mg/kg) – A solid concentrationmeasurement. One milligram of a substance in 1 kilogram of soil,which is also equal to a concentration of 1 ppm for that substancein soil (see definition for parts per million).Milligram per liter (mg/L) – A liquid concentrationmeasurement. One milligram of a substance in 1 liter of water isalso equal to a concentration of 1 ppm in water (see definition forparts per million).Monitored Natural Attenuation (MNA) – An environmentalcleanup strategy in which naturally occurring processes (alsoknown as intrinsic remediation) are allowed to cleanupcontaminants. Environmental sampling is used to monitor thecleanup process.MWH – Montgomery Watson Harza.Ethylbenzene –A colorless, volatile, flammable organic liquid(C8H10) with a sweet, gasoline-like odor used in a variety ofchemical products, including motor fuel.NALEMP – Native American Land Environmental MitigationProgram.EPA – United States Environmental Protection Agency.National Contingency Plan (NCP) – The regulations that providethe structure and procedures for responding to discharges of oil andhazardous substances, as directed by CERCLA.Feasibility Study (FS) – An evaluation of site conditions andpotentially applicable remedial actions.No Further Response Action Planned (NFRAP) - A category ofsite response that identifies that no further remedial responseactivity is necessary to protect human health and the environment;thus no further remedial action will be performed there. NFRAPdiffers from site closure in that NFRAP sites require institutionalcontrols to restrict access to contamination remaining at the site;whereas closed sites are available for unrestricted use and access.NFRAP sites are tracked in USAF and ADEC databasesRemedial Action – Action taken to permanently eliminate, reduce,or control the hazards posed by hazardous substances, pollutants orcontaminants at a site.OSCI – Oil Spill Consultants, Inc.Remedial Investigation (RI) – An evaluation of site conditions todetermine the nature and extent of contamination. The RIemphasizes data collection and site characterization, and includessampling and monitoring, as necessary.Parts per million (ppm) - A unit of measure used to expressextremely low concentrations of chemicals in media such as soil orwater. As an analogy, one ounce of a chemical in a million ouncesof water is 1 ppm and is also equivalent to 12 seconds of time in aperiod of 12 days. Equivalent units for 1 ppm can be expressed as 1mg/L (water) or 1 mg/Kg (soil).Polyaromatic (or Polycyclic) Hydrocarbons (PAHs) – A class ofvery stable organic molecules made up of only carbon andhydrogen (benzene rings). They occur naturally in crude oil andrefined products (such as diesel fuel) and also occur as products ofincomplete combustion. Some PAHs are highly carcinogenic (e.g.,benzo(a)pyrene).Polychlorinated biphenyls (PCBs) – A group of toxic, persistentchemicals used in transformers and capacitors for insulatingpurposes and in gas pipeline systems as a lubricant.Priority Pollutant Metals – Antimony, arsenic, barium,beryllium, cadmium, chromium, copper, lead, mercury, nickel,selenium, silver, thallium, and zinc.Proposed Plan – A document required by section 117(a) ofCERCLA that informs the public about alternatives that areconsidered for cleanup of a contaminated site and identifies apreferred cleanup alternative. The document encourages publiccomment on all alternatives.RCRA – Resource, Conservation and Recovery Act. The federallaw which regulates the generation, transport, and disposal ofhazardous wastes.RCRA metals – arsenic, barium, cadmium, chromium, lead,mercury, selenium, and silver.Record of Decision (ROD) – As required by CERCLA section117(b), a document of the final cleanup decision under the sitecleanup rules. The ROD documents the rationale for selection ofthe cleanup remedy and establishes performance goals forachieving cleanup. A ROD issued by or for ADEC is similar to aUSAF Decision Document or an EPA ROD, but its format maydiffer. The format for an ADEC ROD is specified in the ADECGuidance on Decision Documentation Under the Site CleanupRules (July 1999).Residual Range Organics (RRO) – heavy-range petroleumproducts such a lubricating oils, with petroleum hydrocarboncompounds corresponding to an alkane range from the beginningof C25 to the beginning of C36 and a boiling point range betweenapproximately 400° C and 500° C (definition from 18AAC75.341)Restoration Advisory Board (RAB) – An advisory body withdiverse community representation designed to act as a focal pointfor the exchange of information between the USACE andinterested stakeholders.Responsiveness Summary – A summary of oral and/or writtenpublic comments received during a comment period and theresponses to those comments. The responsiveness summary is partof the decision document or ROD.Removal/Remedial Actions (RA) – Actions taken to abate,prevent, minimize, stabilize, mitigate, or eliminate the release orthreat of a release of contaminants.Screening Level – A number used for comparison with datacollected during the remedial investigation. They include the mostconservative ADEC Table B cleanup levels or a risk-based levelpublished by the US EPA.Site Closure – A written determination by ADEC that a site wasadequately characterized and achieved the applicable requirementsunder the site cleanup rules (18 AAC 75.380(d)(1)).SVOCs – Semi volatile organic compounds.TAL metals – Target Analyte List metals. Includes aluminum,antimony, arsenic, barium, beryllium, cadmium, calcium,chromium, cobalt, copper, iron, lead, magnesium, manganese,mercury, nickel, potassium, selenium, silver, sodium, thallium,vanadium, and zinc.TCLP – Toxicity characteristic leaching procedure. A laboratorymethod used to determine the amount of a compound that could bepresent in water beneath a landfill.Ten Times Rule – a provision set out in 18 AAC 75.350 thatstipulates that cleanup levels may be adjusted in cases wheregroundwater is not considered drinking water. In order to use theten times rule, groundwater must meet criteria set out in 18 AAC75.350 considering the suitability of the aquifer for a drinkingwater source, historical and potential future use of the aquifer for adrinking water source, and the availability of alternative drinkingwater sources.Toluene – A colorless, volatile, flammable liquid, C7H8, used inaviation fuel and other high-octane fuels, in dyestuffs, explosives,and as a solvent for gums and lacquers.TRPH – Total recoverable petroleum hydrocarbons.United States Army Corps of Engineers (USACE) – The agencyresponsible for cleanup of former military sites.Upper Confidence Level (95%UCL) – The value at which thereis a 95% likelihood that 95% of the dataset is below this value (e.g.the upper boundary). The UCL is also considered a reasonableestimate of the maximum exposure concentration.VOCs – Volatile organic compounds.Xylenes – A group of colorless, volatile, flammable liquids(C6H10) with a sweet odor that are used in a variety of productsincluding motorPUBLIC COMMENT FORMYour comments and suggestions on the preferred remedial alternatives discussed in thisProposed Plan are important to the Corps of Engineers. We will not select a final course ofaction until the public comment period ends and all comments have been reviewed andconsidered. You may use the space below to provide your comments. When finished, please foldand mail. A return address has been provided on the back of this page for your convenience.Comments must be postmarked by: August 23, 2004Name:Address:City/State/Zip:Telephone:(Use this space to write your comments)---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------AffixPostageHereU.S. Army Corps of Engineers, Alaska DistrictCEPOA-PM-C-FUDSAttn: Carey CossaboomPO Box 6898Elmendorf AFB, AK 99506-6898