UNDERGROUND STORAGE TANK DECOMMISSIONING         AND RISK-BASED CLOSURE      FORMER FRONTIER LEATHER SITE         15104 SW...
UNDERGROUND STORAGE TANK DECOMMISSIONING                     AND RISK-BASED CLOSURE                           FORMER FRONT...
CONTENTSTABLES AND FIGURES...................................................................................................
6.4        Subsurface Soil Confirmation Sampling ...................................................................... 19...
TABLES AND FIGURESTable                                                                                                   ...
ACRONYMS AND ABBREVIATIONSAPI                     American Petroleum Institutebgs                     below ground surface...
EXECUTIVE SUMMARYThe former Frontier Leather Company property, located at 15104 SW Oregon Street inSherwood, Oregon, is un...
•    Constituents of potential concern in ground water were naphthalene,               trichloroethene, 1,2,4- trimethylbe...
1.0       INTRODUCTIONThe former Frontier Leather Company property, located at 15104 SW Oregon Street inSherwood, Oregon (...
discovered inside the tank (the presence of this solid debris was unknown when the workplanwas submitted and approved). Si...
8. Submitted soil and ground-water samples to an independent Oregon Environmental       Laboratory Accreditation Program (...
2.0    SITE SETTING2.1      Location and DescriptionThe former Frontier Leather Company property is located at 15104 SW Or...
neighboring site, monitoring well logs indicate that silty sand directly underlies the surficial fillmaterials to a depth ...
3.0     METHODS AND PROCEDURESThe SOW for this project (see Section 1.3) was performed with the following specific objecti...
3.2      Soil and Ground Water SamplingAfter the UST was removed, residual oil impacts were indicated in the tank excavati...
analyzed for PAHs by EPA method 8270 and by method NWTPH-HCID, as required by theODEQ UST Program. Copies of the laborator...
•    Number of potential receptorsThe Soil Matrix score appropriate for the site was determined to be 25, indicating Level...
4.0    UST DECOMMISSIONING4.1      UST DescriptionThe UST was oriented east to west and was determined to be approximately...
of the tank. WCM utilized confined space procedures. Approximately 2,500 gallons of tankfluids (profiled as waste oil) wer...
5.0      IMPACTED SOIL REMOVAL AND ASSOCIATED SOIL AND                          GROUND-WATER SAMPLINGRemoval of the UST ex...
As previously approved by ODEQ, arsenic-impacted soils stockpiled at the site (resulting fromprevious environmental cleanu...
6.0    ANALYTICAL RESULTSThis section presents the results of the soil and ground-water sampling activities associatedwith...
DRO was detected in GS05 (collected from the western test pit) and GS06 (collected from theeastern test pit) at concentrat...
sampling locations are shown in Figure 4. The analytical results are presented in Table 1, afterthe text, and are describe...
impacts and upper most ground-water table are found). Based on this information anddiscussions with the ODEQ, the ground-w...
7.0    RISK-BASED ASSESSMENTWhere impacts to soil and ground water are present, the impacts must be evaluated using arisk-...
7.2.1 SoilTable 1 summarizes the risk-screening of soil samples collected during the UST remedialactions. As described in ...
Additionally, although the entire site will reportedly be paved, this assessment willconservatively consider possible expo...
Table 7-1. Summary of Pathway Analysis for Human Receptors   Potentially                    Exposure Route, Medium and Exp...
by the identified complete exposure pathways; therefore, RRO itself does not present anunacceptable health risk by the ide...
of future ground-water use. This indicates that the ground water impacts from the former USTare limited in nature and are ...
8.0   CONCLUSIONS AND RECOMMENDATIONSAn approximate 8,000-gallon capacity UST was discovered in October 2007 during demoli...
9.0     LIMITATIONSThe scope of this report is limited to observations made during on-site work; interviews withknowledgea...
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I purchased a former leather tannery and battery manufacturing plant in Sherowod, Oregon under a "Prospective Purchaser Agreement" with the Oregon DEQ. This report is the final remediation report on many aspects of the environmental cleanup. We removed chromium contaminated soils and leather hide splits, lead contaminated soil from 300,000 battery casings that caught fire in the late 1960's, arsenic soils and concrete, benzine, and many other toxic substances I can't even pronounce. Some of the debris had to be hauled to a hazardous waste facility in S.E. Idaho.

I received a No Further Action determination from the Oregon DEQ for the extensive work that was performed under their supervision. Would I do this kind of project again? No way. But I am proud of the accomplishment and what it did for the community that I live in.

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final ust decommissioning report

  1. 1. UNDERGROUND STORAGE TANK DECOMMISSIONING AND RISK-BASED CLOSURE FORMER FRONTIER LEATHER SITE 15104 SW OREGON STREET SHERWOOD, OREGON 97104 LUST FILE NO.: 34-07-1896 (ESCI FILE NO.: 116, FACILITY 2687) Prepared on behalf of: Creekside Environmental Consulting, LLC 21790 Southwest Chehalis Court Tualatin, Oregon 97062 T. (503) 692-8118 F. (503) 885-9702 Prepared by: PO Box 80747 Portland, Oregon 97280-1747 T. 503-452-5561 F. 503-452-7669 Project No.: 351-05009-06 February 8, 2008 (revised March 6, 2008)
  2. 2. UNDERGROUND STORAGE TANK DECOMMISSIONING AND RISK-BASED CLOSURE FORMER FRONTIER LEATHER SITE 15104 SW OREGON STREET SHERWOOD, OREGON 97104 LUST FILE NO.: 34·07·1896 (ESCI FILE NO.: 116, FACILITY 2687) Prepared by: Mike Krzeminski, Environmental Scientist, ENW Decommissioning Supervisor License Number: 26613 Expiration Date: November 27. 2009 Soil Matrix Supervisor License Number: 26612 Expiration Date: November 27. 2009 HOT Supervisor License Number: 6614 Expiration Date: November 27.2009 Reviewed by: ~~ Neil Woller, R.G., Senior Hydrogeologist, EN Project No.: 351-05009-06 February 8, 2008 (revised March 6, 2008)EVREN Northwest, Inc. 351-05009-06, Rev. 0, 3/6/08
  3. 3. CONTENTSTABLES AND FIGURES.............................................................................................................................. 1ACRONYMS AND ABBREVIATIONS ......................................................................................................... 2EXECUTIVE SUMMARY .............................................................................................................................. 31.0 INTRODUCTION.............................................................................................................................. 5 1.1 Background ....................................................................................................................... 5 1.2 Purpose.............................................................................................................................. 6 1.3 Scope of Work ................................................................................................................... 62.0 SITE SETTING................................................................................................................................. 8 2.1 Location and Description................................................................................................. 8 2.2 Topography ....................................................................................................................... 8 2.3 Geologic Setting................................................................................................................ 8 2.4 Hydrogeologic Setting...................................................................................................... 9 2.4.1 Surface Water....................................................................................................... 9 2.4.2 Ground Water ....................................................................................................... 93.0 METHODS AND PROCEDURES.................................................................................................. 10 3.1 UST Decommissioning................................................................................................... 10 3.2 Soil and Ground Water Sampling.................................................................................. 11 3.2.1 Soil....................................................................................................................... 11 3.2.2 Ground Water ..................................................................................................... 11 3.2.3 Analytical Methods ............................................................................................ 11 3.3 Cleanup Standards ......................................................................................................... 12 3.3.1 Soil Matrix Cleanup Standards ......................................................................... 12 3.3.2 Risk-Based Decision Making............................................................................ 13 3.3.3 Background Concentrations (Metals).............................................................. 13 3.4 Waste Management and Disposal................................................................................. 134.0 UST DECOMMISSIONING............................................................................................................ 14 4.1 UST Description .............................................................................................................. 14 4.2 Fluid Removal.................................................................................................................. 14 4.3 UST Exposure by Soil Removal..................................................................................... 14 4.4 UST Cleaning................................................................................................................... 145.0 IMPACTED SOIL REMOVAL AND ASSOCIATED SOIL AND GROUND-WATER SAMPLING 16 5.1 January 23, 2008 ............................................................................................................. 16 5.2 January 24, 2008 ............................................................................................................. 16 5.3 January 25, 2008 ............................................................................................................. 16 5.4 January 31, 2008 ............................................................................................................. 17 5.5 February 1, 2008.............................................................................................................. 176.0 ANALYTICAL RESULTS .............................................................................................................. 18 6.1 Characterization Sampling............................................................................................. 18 6.2 Residual Subsurface Soil Characterization Sampling ................................................ 18 6.3 Surface Soil Confirmation Sampling ............................................................................ 19EVREN Northwest, Inc. iii 351-05009-06, Rev. 0, 3/17/08
  4. 4. 6.4 Subsurface Soil Confirmation Sampling ...................................................................... 19 6.5 Ground Water Sampling Results................................................................................... 207.0 RISK-BASED ASSESSMENT....................................................................................................... 22 7.1 Identification of Constituents of Interest...................................................................... 22 7.2 Identification of Constituents of Potential Concern.................................................... 22 7.2.1 Soil....................................................................................................................... 23 7.2.2 Ground Water ..................................................................................................... 23 7.3 Conceptual Site Model ................................................................................................... 23 7.3.1 Media of Concern............................................................................................... 23 7.3.2 Land Use and Ground Water Use – Potential Receptors .............................. 23 7.3.3 Pathways of Concern ........................................................................................ 24 7.3.4 Developed Conceptual Site Model ................................................................... 25 7.3.5 Evaluation of COPCs ......................................................................................... 25 7.3.5.1 Subsurface Soil .................................................................................................. 25 7.3.5.2 Ground Water ..................................................................................................... 26 7.4 Evaluation of Risk to the Environment ......................................................................... 26 7.5 Discussion ....................................................................................................................... 278.0 CONCLUSIONS AND RECOMMENDATIONS............................................................................. 289.0 LIMITATIONS ................................................................................................................................ 29APPENDICESAPPENDIX A ODEQ UST REGISTRATION, DECOMMISSIONING NOTIFICATION, CHECKLIST AND REPORTAPPENDIX B SITE PHOTOGRAPHSAPPENDIX C LABORATORY ANALYTICAL REPORTSAPPENDIX D SOIL MATRIX SCORE SHEET AND CHECKLISTAPPENDIX E WASTE RECEIPTSEVREN Northwest, Inc. iv 351-05009-06, Rev. 0, 3/17/08
  5. 5. TABLES AND FIGURESTable Location3-1 Analytical Methods ............................................................................................... Section 47-1 Summary of Pathway Analysis for Human Receptors.......................................... Section 57-2 Risk Evaluation of Identified COPCs in Soil......................................................... Section 57-3 Risk Evaluation of Identified COPCs in Ground Water ........................................ Section 51 Summary of Analytical Results, Soil .......................................... Behind Text (Tables Tab)2 Summary of Analytical Results, Ground Water .......................... Behind Text (Tables Tab)Figure Figure No.Site Vicinity Map ........................................................................................................................... 1Site Plan........................................................................................................................................ 2Sampling Location Diagram, Soil (as of 1/24/2008)...................................................................... 3Sampling Location Diagram, Soil (as of 2/1/2008)........................................................................ 4Sampling Location Diagram, Ground Water ................................................................................. 5Residual Petroleum Concentrations (In Situ) Remaining at the Site ............................................ 6Conceptual Site Model (in text)..................................................................................................... 7EVREN Northwest, Inc. 1 351-05009-06, Rev. 1, 3/17/08
  6. 6. ACRONYMS AND ABBREVIATIONSAPI American Petroleum Institutebgs below ground surfaceBTEX benzene, tolulene, ethylbenzene and total xylenesCERCLIS Comprehensive Environmental Response, Compensation and Liability Information SystemCOIs constituents of interestCOPCs constituents of potential concernCreekside Creekside Environmental ConsultingDRO diesel-range organicsENW EVREN Northwest, Inc.EPA U. S. Environmental Protection AgencyGRO gasoline-range organicsLUST Leaking Underground Storage Tankmg/Kg milligrams/Kilogramµg/L micrograms per LiterNRC NRC Environmental ServicesNWTPH-Dx Northwest analytical method for diesel and oilNWTPH-HCID Northwest analytical method for hydrocarbon identificationODEQ Oregon Department of Environmental QualityOARs Oregon Administrative RulesOVM organic vapor monitorORELAP Oregon Environmental Laboratory Accreditation ProgramOWRDGD Oregon Water Resources Department Grid DatabasePAHs polynuclear aromatic hydrocarbonsPCBs polychlorinated biphenylsPSC Philip Services CorporationRBCs risk-based concentrationsRBDM Risk-Based Decision Making for Remediation of Petroleum Contaminated Sites, ODEQ September 2003 Guidance DocumentRCRA Resource Conservation and Recovery ActRRO residual (oil) range organicsSOW scope of workTCE trichloroethyleneTMB trimethylbenzeneUSGS United States Geological SurveyUST underground storage tankVEC Varchan Environmental ConstructionVOCs volatile organic compoundsWCM West Coast Marine Cleaning, Inc.EVREN Northwest, Inc. 2 351-05009-06, Rev. 1, 3/17/08
  7. 7. EXECUTIVE SUMMARYThe former Frontier Leather Company property, located at 15104 SW Oregon Street inSherwood, Oregon, is undergoing Oregon Department of Environmental Quality-directedenvironmental cleanup related to historical tannery operations conducted at the site. In October2007, an approximate 8,000-gallon capacity underground storage tank was discovered duringdemolition of the concrete floor slab of the tannery facility building at the subject site.Characterization of the tank contents and soil above the tank indicated that the tank was mostlikely used as a waste oil tank and that the residual contents required management as ahazardous waste; impacted soils were approved for disposal at a Subtitle D landfill. A work planfor decommissioning the tank was prepared for and approved by the Oregon Department ofEnvironmental Quality.In December 2007 and January 2008, fluid and solid debris were removed from the tank andtaken to appropriate disposal facilities. Following removal of the tank contents, the tank wasthoroughly cleaned, removed from the ground with a crane, and transported off-site for recyclingin accordance with national standards of practice. Upon removal, the tank was observed to beattached with metal straps to a concrete mold around the bottom half of the tank, designed toact as a “dead man” weight to keep the tank firmly in place under potentially buoyant conditions.The top of the concrete mold was measured at approximately four (4) feet below groundsurface. Soils surrounding the tank were visibly impacted. Ground water was encountered atapproximately five (5) feet below ground surface.Removal of the tank also revealed residual impacted soils; characterization samplesrepresentative of “worst case” impacts were collected. Subsequently, over the course of a weekand with Oregon Department of Environmental Quality involvement, impacted soils wereremoved, ground-water samples were collected from test pits located at either end of the formertank location and confirmation soil samples were collected. Excavated soils were placeddirectly in trucks and transported to Hillsboro Landfill for disposal.As previously approved by the Oregon Department of Environmental Quality, stockpiled arsenic-impacted soil was used to backfill the UST excavation to within four(4)-feet of the groundsurface (approximately 30 cubic yards). The balance of the stockpile was then transported toHillsboro Landfill.Soil and ground-water sampling results indicated that: • All impacts to shallow surface soil (up to three [3] feet depth) were removed. • Constituents of potential concern in subsurface soils in the vicinity of the former underground storage tank were benz[a]anthracene, naphthalene, and diesel- and residual-range organics. (Concentrations of these constituents exceeded their respective conservative risk-based screening levels from state guidance.)EVREN Northwest, Inc. 3 351-05009-06, Rev. 1, 3/17/08
  8. 8. • Constituents of potential concern in ground water were naphthalene, trichloroethene, 1,2,4- trimethylbenzene, and diesel- and residual-range organicsA risk-based assessment was performed for the constituents commonly associated with wasteoil. A conceptual model was developed to identify complete exposure pathways from therelease source to human receptors. The potential receptors were identified as occupationalworkers and excavation/trench workers. Pathways identified as complete were volatilization intointerior and exterior air for occupational workers and dermal contact-incidental ingestion forexcavation workers and construction workers. Based on the conceptual model performed aspart of the risk-based assessment, none of the constituents of potential concern in eithersubsurface soils or ground water is likely to cause an unacceptable health risk by the identifiedcomplete exposure pathways. Therefore no additional investigation or remediation is requiredat this time.ENW recommends that a Soil and Ground Water Management Plan which describesappropriate handling and disposal procedures be developed in the event that residual impactedsoils and/or ground water are disturbed in the future. ENW further recommends that ODEQgrant regulatory closure to LUST File No. 34-07-1896 and issue a “No Further Action Required”letter. The property owner is required to keep a copy of this report and regulatory closure letterfor ten years after he/she sells or otherwise transfers the property.EVREN Northwest, Inc. 4 351-05009-06, Rev. 1, 3/17/08
  9. 9. 1.0 INTRODUCTIONThe former Frontier Leather Company property, located at 15104 SW Oregon Street inSherwood, Oregon (subject site; Figure 1), is undergoing Oregon Department of EnvironmentalQuality (ODEQ)-directed environmental cleanup related to historical tannery operationsconducted at the site. This report describes the decommissioning of an underground storagetank (UST) discovered during site demolition and the risk-based assessment of associatedimpacted soil and ground water.This work was performed in accordance with the Workplan for Underground Storage TankDecommissioning 1 , which was approved by the ODEQ in January of 2008. CreeksideEnvironmental Consulting (Creekside) requested EVREN Northwest, Inc. (ENW) to collaborateon the project and prepare this report.1.1 BackgroundThe former Frontier Leather Company, which began operating a tannery at the subject site in1947, is an Environmental Protection Agency (EPA) Comprehensive Environmental Response,Compensation and Liability Information System (CERCLIS) listed site (CERCLIS No.009043357) and ODEQ Environmental Cleanup Site Information (ECSI) listed site (ECSI No.116, Facility 2687). Numerous site investigations with extensive regulatory involvement havetaken place at the subject site. A comprehensive history of the site is described in a March2006 progress report compiled by Creekside 2 .In October 2007, an abandoned, approximately 8,000-gallon capacity UST was identified duringdemolition of the concrete floor slab of the tannery facility building (the UST was originallythought to be 10,000 gallons in capacity, but exposure by excavation showed that it wassmaller).Initial characterization samples of the UST contents indicated that the tank contained waste oil(based on analysis by analytical method NWTPH-HCID [hydrocarbon identification]); analyticalresults are presented in Table 1, following the text. Detections included low-levelconcentrations of several volatile organic constituents (VOCs): benzene, toluene,ethylbenzene, total xylenes (collectively referred to as BTEX constituents), naphthalene, cis-1,2-dichloroethylene, trichloroethylene (TCE), and trimethylbenzenes (TMBs). Profiling conductedby Creekside showed the UST contents to be hazardous waste.During initial removal of the fluids from the tank, large quantities of solid debris (described indetail in Section 3.1 of this report) including concrete rubble, soil, wood and metal waste were1 ENW. , 2008. Workplan for Underground Storage Tank Decommissioning, Former Frontier Leather Company Site. January.2 Creekside. 2006. Progress Report No. FL-2006-1, Fire Debris Demolition & Disposal, Former Frontier Leather Facility, DEQ ECSI #116. March 20.EVREN Northwest, Inc. 5 351-05009-06, Rev. 1, 3/17/08
  10. 10. discovered inside the tank (the presence of this solid debris was unknown when the workplanwas submitted and approved). Since demolition activities were underway at the site, it is likelythat this material was accidentally bulldozed into the tank prior to its discovery. Consequently,the solid debris inside the tank was also managed as a hazardous waste.The introduction of this solid debris into the tank apparently displaced the fluid contents, causingan “overspill” out of the access ports in the top of the tank, impacting surface soils in theimmediate vicinity of the tank. The release was reported to the ODEQ’s Leaking UndergroundStorage Tank (LUST) Program, and was assigned LUST File No. 34-07-1896. Based onanalytical data for the impacted surface soils, ODEQ permitted these soils to be transported anddisposed at a Subtitle D landfill. 3This report specifically addresses the UST decommissioning and related activities for the abovereferenced LUST file. All other work at the site is being performed for and directed by theODEQ’s Cleanup Program.1.2 PurposeThe purpose of the project was to decommission the UST in a safe and appropriate mannerfollowing applicable guidance and regulations and to properly address associated impacted soiland ground water, with a goal of obtaining regulatory closure for the LUST file at the site fromODEQ.1.3 Scope of WorkENW completed the following Scope of Work (SOW) for this project: 1. Submitted a work plan outlining proposed decommissioning methods to ODEQ for approval. 2. Registered the UST system with ODEQ and provided notice of decommissioning (Appendix A). 3. Provided a health and safety plan for staff and subcontractors on-site during this SOW. 4. Obtained appropriate Resource Conservation and Recovery Act (RCRA) hazardous waste disposal permits. 5. Decommissioned the UST per national standards of practice. 6. Performed soil removal to remediate the most impacted soils from the UST location. 7. Characterized and delineated remaining subsurface soil and ground-water impacts beneath the former tank location.3 The tank waste was determined to be a listed hazardous waste based on concentrations of TCE. The soil was tested to determine if it was characteristic hazardous waste based on Toxicity Characteristic Leaching Procedure (TCLP) results for TCE. The soil did not fail TCLP criteria (i.e., 0.5 mg/L) and was managed as a special waste and disposed of at the Hillsboro Landfill.EVREN Northwest, Inc. 6 351-05009-06, Rev. 1, 3/17/08
  11. 11. 8. Submitted soil and ground-water samples to an independent Oregon Environmental Laboratory Accreditation Program (ORELAP) accredited laboratory for chemical analyses under chain-of-custody documentation. 9. Evaluated analytical results with respect to Oregon Soil Matrix Cleanup Regulations and ODEQ’s Risk-Based Decision Making for Remediation of Petroleum-Contaminated Sites (RBDM) September 2003 guidance document. 10. Restored the UST excavation to an acceptable condition using ODEQ-approved backfill materials. 11. Prepared this report to ODEQ documenting work conducted, findings and analytical data, and requesting closure in-place of residual impacts.The field activities described in this report were performed from October 2007 to February 1,2008.EVREN Northwest, Inc. 7 351-05009-06, Rev. 1, 3/17/08
  12. 12. 2.0 SITE SETTING2.1 Location and DescriptionThe former Frontier Leather Company property is located at 15104 SW Oregon Street in acommercial-residential district of the city of Sherwood, Oregon (Figure 1). The site is boundedby a wetlands area to the north, SW Oregon Street to the east and south, and railroad tracks tothe west (see Figure 2). Commercial properties are present further to the north and west, and asingle family residential neighborhood is present to the east and south, across SW OregonStreet. The site is zoned Light Industrial (LI) by the City of Sherwood.The site has recently been cleared of all the former structures and is currently vacant andundeveloped. The UST which is the subject of this report was located in the western portion ofthe property, beneath the northern portion of the former tannery building (Figure 2).2.2 TopographyThe subject site is located within the U.S. Geological Survey (USGS) Sherwood 7.5-minutequadrangle, at an approximate elevation ranging from 195 to 125 feet above mean sea level(Figure 1). The site slopes gently to moderately to the northeast, towards Rock Creek. RockCreek flows northward and discharges to the Tualatin River, located approximately two (2) milesto the north of the subject property.2.3 Geologic SettingThe subject property is located in the Tualatin River Basin of northwestern Oregon. TheTualatin River Basin is a structural depression between the Chehalem Hills to the south, OregonCoast Range to the west, and Tualatin Mountains and Portland Hills to the northeast and east.The erosional and depositional alluvial processes of the Tualatin River and its tributary streamshave modified the structural depression of the basin. Sediments within the basin fill includeerosional products of the surrounding highlands. In addition, during late Pleistocene time(approximately 12,000-years before present), numerous catastrophic floods (Missoula Floods)backwashed into the Tualatin River Basin from the Willamette Valley to the east. These floodwaters deposited large volumes of sediment throughout the Basin, and at times were dammedup within the basin before being released to down-gradient areas.During the soil removal activities described in this report, soils encountered beneath the siteconsisted of fill materials from the surface to around four (4) feet below ground surface (bgs).Underlying the fill layer was silty clay with medium sands to around ten (10) feet bgs.ENW accessed the Oregon Water Resources Department Grid Database (OWRDGD) todetermine subsurface conditions in the vicinity of the subject site. Several monitoring wellscompleted at the site encountered silty clay soils below fill materials to an approximate depth of11 feet, which were in turn underlain by silt, silty sand, and sand to 18 feet bgs. At aEVREN Northwest, Inc. 8 351-05009-06, Rev. 1, 3/17/08
  13. 13. neighboring site, monitoring well logs indicate that silty sand directly underlies the surficial fillmaterials to a depth of 25 feet, which in turn overlies at least five (5) feet of weathered silty clay.2.4 Hydrogeologic Setting2.4.1 Surface WaterTopographic mapping by the USGS indicates that the site slopes gently northeastward towardRock Creek. Consequently surface drainage, where unmodified, is also toward the northeast.The site is outside the 100-year flood plain and does not contain any wetlands. 42.4.2 Ground WaterGround water was encountered during the decommissioning activities at around nine (9) feetbgs, rising to a depth of approximately five (5) feet in excavations. Based on hydrogeologicstudies at the site, ground-water flow direction should be toward the northeast.4 City of Portland’s website: www.portlandmaps.comEVREN Northwest, Inc. 9 351-05009-06, Rev. 1, 3/17/08
  14. 14. 3.0 METHODS AND PROCEDURESThe SOW for this project (see Section 1.3) was performed with the following specific objectives: • To conduct a thorough and cost-effective UST decommissioning and associated work that meets both the needs of our client and the requirements of applicable regulations. • To perform the decommissioning and associated field-work in a safe manner for technical personnel as well as others, and with minimum permanent impacts to the subject site. • To ensure that information and data collected is certifiable and valid for the intended use.The rest of this section describes the methods and procedures used to conduct the USTdecommissioning and associated work; following sections describe the work and findings. Aphotographic log of all the field work is presented in Appendix B.3.1 UST DecommissioningDecommissioning of the UST system was based on the procedures referenced in the followingdocuments: 1. American Petroleum Institute (API) 2015, "Cleaning Petroleum Storage Tanks," 1994. 2. ODEQ, "Cleanup Rules for Leaking Petroleum UST Systems," November 1998.In October and November of 2007, Creekside characterized both the UST contents andsurrounding surface soils (visually observed to be impacted). Based on the analytical results(described in Section 6.1) and ODEQ’s hazardous waste regulations, the product within the tankwas determined to be a hazardous waste (requiring disposal at an appropriate hazardous wastefacility). The impacted surface soils, although considered hazardous waste under the“contained-in” rule, could be disposed at a Subtitle D landfill under ODEQ authorization3.Prior to commencing UST decommissioning activities: • Appropriate notice of decommissioning was given to the ODEQ. • A utility locate was provided by the “one call” public utility locate service. • A health and safety tailgate meeting was conducted (as needed) with all on-site personnel and subcontracts to review the site health and safety plan and the scope of work prior to entering the site.Details of the UST decommissioning are described in Section 4.0.EVREN Northwest, Inc. 10 351-05009-06, Rev. 1, 3/17/08
  15. 15. 3.2 Soil and Ground Water SamplingAfter the UST was removed, residual oil impacts were indicated in the tank excavation. Section5.0 describes the remedial activities and summarizes the collection of soil and ground-watersamples. Sampling methods and procedures are described here.3.2.1 SoilAll soil samples were collected from freshly excavated soils in the excavator bucket andtransferred with fresh Nitrile gloves into sample containers provided by the laboratory.Headspace within the containers was minimized before sealing. Samples were also placed inZiploc bags for headspace screening with an organic vapor monitor (OVM) and fieldidentification. The samples were each marked with a distinctive designation, the date, time,project number, and sampler’s name, and then immediately placed in cooled storage untildelivered to the laboratory under chain-of-custody protocols.Additionally, samples for volatile organic compound (VOC) analyses were collected according tothe proscribed procedures of U.S. Environmental Protection Agency (EPA) Method 5035A,using sampling kits provided by the laboratory.3.2.2 Ground WaterGround-water samples were collected using a clean disposable plastic bailer and immediatelytransferred to laboratory-supplied bottles. Ground-water samples to be analyzed for dieselrange organics (DRO) were collected in 500-milliliter glass amber bottles preserved withaliquots of hydrochloric acid. Ground-water samples to be analyzed for VOCs were collected involatile organic analysis vials preserved with aliquots of hydrochloric acid, prepared by thelaboratory. Water samples collected for polynuclear aromatic hydrocarbons (PAHs) analysiswere collected in unpreserved one (1)-liter brown glass containers (Boston Rounds). Thesample containers were filled completely and immediately sealed to eliminate headspace. Thesamples were each marked with a distinctive designation, the date, time, project number, andsampler’s name, and then immediately placed in cooled storage until delivered to the laboratoryunder chain-of-custody protocols.3.2.3 Analytical MethodsLaboratory analyses were performed by Friedman & Bruya, Inc., of Seattle, Washington.Initially, analyses of the tank fluid and impacted surface soil (initial characterization samples)were performed for gasoline, diesel and heavy oil range hydrocarbons by Northwest TotalPetroleum Hydrocarbon Identification (NWTPH-HCID), reported as detected or not detected.Based on the results, these samples were further quantified for diesel range organics (DRO)and residual oil range organics (RRO) by NWTPH-Dx. The samples were also analyzed forVOCs by EPA Method 8260; for RCRA metals by EPA Method 200.8, and for polychlorinatedbiphenyls (PCBs) by EPA method 8082.Based on the results of the initial characterization samples, all subsequent soil and ground-water samples were analyzed only for DRO, RRO, and VOCs. Selected samples were alsoEVREN Northwest, Inc. 11 351-05009-06, Rev. 1, 3/17/08
  16. 16. analyzed for PAHs by EPA method 8270 and by method NWTPH-HCID, as required by theODEQ UST Program. Copies of the laboratory analytical reports are provided in Appendix C.Table 3-1 describes the analytical plan. Table 3-1. Analytical Plan Analytical Tank Fluid Ground Constituents Soil Method (Product) Water Initial surface soil NWTPH- Northwest Total Petroleum Initial fluid in characterization sample, Not analyzed HCID Hydrocarbon Identification tank and UST assessment samples Total Petroleum Hydrocarbons– Diesel-range extended quantification [diesel-range Initial fluid in NWTPH-Dx All samples All samples petroleum hydrocarbons (DRO) tank and oil-range petroleum hydrocarbons (RRO)] RCRA 8 Hazardous Metals EPA 200.8; (Arsenic, barium, cadmium, Initial fluid in Not analyzed Not analyzed 7471A chromium, lead, mercury, tank selenium, silver) Initial fluid in Initial surface soil EPA 8082 Polychlorinated Biphenyls (PCBs) Not analyzed tank characterization sample Volatile Organic Compounds Initial fluid in EPA 8260 All samples All samples (VOCs) tank Selected Sample with highest EPA 8270 Polyaromatic Hydrocarbons (PAHs) Not analyzed Sample DRO concentration3.3 Cleanup Standards3.3.1 Soil Matrix Cleanup StandardsThe Oregon Administrative Rules (OARs) 340-122-0205 through 0360 (Soil Matrix CleanupRules) were developed as part of the UST Cleanup Rules. However, the ODEQ’s Risk-BasedDecision Making for the Remediation of Petroleum-Contaminated Sites (RBDM) guidancedocument (2003 revision) states that the Soil Matrix Cleanup levels developed under those rulesare considered to be adequately protective for petroleum contamination regardless of source.Therefore the Soil Matrix Cleanup standards may also be used as cleanup levels for sites beingremediated under the Hazardous Substance Remedial Action Rules.The Soil Matrix Cleanup Rules permit soil impacts from petroleum hydrocarbons to be cleanedup by setting standards based on site conditions. The cleanup levels are determined for the siteby inputting environmental parameters with site-specific values. The values used in determiningthe Soil Matrix Cleanup level for a site are: • Annual rainfall • Soil type • Sensitivity of the uppermost aquifer • Depth to ground water • Distance to nearest potential receptorsEVREN Northwest, Inc. 12 351-05009-06, Rev. 1, 3/17/08
  17. 17. • Number of potential receptorsThe Soil Matrix score appropriate for the site was determined to be 25, indicating Level IIcleanup standards (80-milligrams per kilogram [mg/Kg] gasoline-range organics [GRO] and 500-mg/Kg DRO and RRO) were appropriate. The Soil Matrix Cleanup Score Sheet and Checklistfor the site are presented in Appendix D.3.3.2 Risk-Based Decision MakingWhere Soil Matrix Cleanup standards are not met, ODEQ allows closure using a risk-basedapproach described in the agency’s RBDM guidance document, 2003 revision. Risk-basedconcentrations (RBCs) tabulated in Appendices A and J of the RBDM guidance document weredeveloped as screening levels for suspect sites based on Oregon unacceptable additional riskcriteria for cancer occurrence and for non-carcinogenic health impacts. The State of Oregonconsiders acceptable additional risk of cancer from contact with carcinogenic constituents atless than one in one million incidences, or, for non-carcinogenic constituents, below theconstituent threshold concentration at which health impacts would occur. Appendix J of theRBDM guidance document additionally states that there is no reason the RBDM approachshould be limited to petroleum hydrocarbons, and the approach described [in the guidancedocument] may be generalized to chemicals other than petroleum hydrocarbons. Residentialstandards were used for initial ‘conservative’ screening.3.3.3 Background Concentrations (Metals)Metals were also compared to default background concentrations in soil determined by theODEQ’s Oregon Toxicology Work Group.3.4 Waste Management and DisposalAll waste generated during the UST decommissioning and associated soil remediation byremoval was properly handled and disposed. Disposal receipts are included in Appendix E anddocument disposal of: Approximately 6,800 gallons of fluid pumped from the UST at PSC’s treatment facility in Tacoma, Washington. Approximately 18 tons of oil-contaminated debris removed from the UST at US Ecology’s treatment facility in Grand View, Idaho. Approximately 2,500 gallons of sludge/rinsate removed from the UST at US Ecology’s treatment facility in Grand View, Idaho. The UST at Metro Metals in Portland, Oregon (to be recycled). Approximately 171 tons of petroleum contaminated soil at Hillsboro landfill under permit # 6159 issued by Waste Management Inc. Approximately 331 tons of arsenic-impacted soil/debris at Hillsboro landfill under permit # 1683 issued by Waste Management Inc.EVREN Northwest, Inc. 13 351-05009-06, Rev. 1, 3/17/08
  18. 18. 4.0 UST DECOMMISSIONING4.1 UST DescriptionThe UST was oriented east to west and was determined to be approximately 21.5 feet in lengthand eight (8) feet in diameter (approximately 8,000 gallons in capacity). The top of the tank wasapproximately flush with the surrounding grade (after removal of all onsite structures andconcrete floors/foundations). Two access ports, each approximately two (2) feet in diameter,were present on the top of the tank, without any locking or latching covers. Upon removal, thetank was observed to be set in a concrete mold (present only around the bottom half of thetank), to which the tank was strapped, acting as a “dead man” weight to keep the tank firmly inplace under potential buoyant conditions. The top of the concrete mold was measured atapproximately four (4) feet bgs. Figure 3 presents the layout of the former UST position.4.2 Fluid RemovalOn December 18, 2007, Philip Services Corporation (PSC) removed a total of 3,000-gallons offluid (profiled as waste oil) from the tank using a vacuum truck. As the level of product in thetank lowered, it was discovered that a significant amount of solid debris was present in thebottom half of the tank. Upon discovery of the solid debris in the tank, no further productremoval was performed that day. PSC disposed of the removed fluid at their treatment facility inTacoma, Washington.On December 27, 2007, NRC Environmental Services (NRC) removed the remaining liquidproduct inside the tank (1,340 gallons) using a vacuum truck. NRC disposed of the removedfluid at the PSC treatment facility in Tacoma, Washington.4.3 UST Exposure by Soil RemovalOn January 21, 2008, Varchan Environmental Construction (VEC) removed the surface soilsoverlying the top of the UST, so it could be accessed for cleaning. The overburden (which hadpreviously been sampled and shown to be impacted; see Section 6.1) was placed directly intotrucks as it was excavated and transported to Waste Managements Subtitle D landfill inHillsboro, Oregon. Upon exposure a large hole was observed in the top of the west end of thetank, and VEC further enlarged the hole in order to facilitate access to the tank’s interior forsolid debris removal and cleaning. It was observed that the tank was approximately half full ofoily fluid. Since fluids had been previously removed from the UST as described above, it wasdetermined that, given the shallow depth of ground water (approximately 5 feet), ground waterwas likely entering the tank through its various corroded holes.4.4 UST CleaningOn January 21 and 22, 2008, West Coast Marine Cleaning, Inc. (WCM) was contracted toremove the remaining oily fluids, sludge, and solid debris from the tank, and to clean the insideEVREN Northwest, Inc. 14 351-05009-06, Rev. 1, 3/17/08
  19. 19. of the tank. WCM utilized confined space procedures. Approximately 2,500 gallons of tankfluids (profiled as waste oil) were pumped using a vacuum truck and taken to PSC’s treatmentfacility in Tacoma, Washington. The solid debris was removed using a Guzzler vacuum truckconnected to an air-tight vacuum box (in which the solids were collected). A total ofapproximately 13 tons of solid debris (profiled as oil-contaminated debris and managed ashazardous waste) was removed from the tank and taken to US Ecology’s treatment facility inGrand View, Idaho.While removing the solid debris from inside the tank, several approximate 15 to 20-gallon steeldrums were found inside the tank. Given their shape and size, they would have fit inside theaccess ports in the top of the tank. The drums were thoroughly corroded, and were likelyplaced inside the tank many years ago (the drums may be a likely source of the chlorinatedsolvents found inside the tank). All large solid debris found in the tank was placed inside a dropbox lined with plastic sheeting (along with all hoses and equipment contaminated during theproduct/debris removal).Once fluids and debris were removed, the UST was cleaned by 1) hand scraping the tankinterior to remove as much sludge as possible, 2) rinsing the tank interior with degreaser cutterstock (diesel), and 3) rinsing the tank interior with fresh water and soap rinse. All remainingsludge in the bottom of the tank (along with all rinsate generated during the tank cleaning) wasremoved using a vacuum truck (included in the fluids total given above).On January 23, 2008, a crane was mobilized to the site in order to remove the tank. VECexcavated additional surface soils surrounding the top of the tank in order to relieve the tankand allow for removal. The soils were observed to be impacted consistent with previouslyremoved overburden and were directly loaded into trucks for disposal to Hillsboro Landfill.Approximately four (4) inches of ground water had accumulated in the bottom of the tankovernight. The crane was used to lift the tank out of its position and tilt the tank slightly in orderto let the ground-water drain from a hole in the bottom of the tank. The tank was placed on atrailer and taken by VEC to Metro Metals in Portland, Oregon for recycling.Upon removal, the tank was observed to be extremely corroded, with many large, through-goingholes. The exterior of the tank was covered with waste oil.The concrete mold that had been used to secure the UST was observed to contain about six (6)inches of product/water and ground-water intrusion into the “saddle” of the mold was observedthrough several holes in the side of the concrete mold. Waste oil product was observed to beseeping into the mold from soils surrounding the top of the mold. The concrete dead-man wasleft in place. See Appendix A for State UST Decommissioning Checklist and Report forms.EVREN Northwest, Inc. 15 351-05009-06, Rev. 1, 3/17/08
  20. 20. 5.0 IMPACTED SOIL REMOVAL AND ASSOCIATED SOIL AND GROUND-WATER SAMPLINGRemoval of the UST exposed visibly impacted soil in the tank excavation. This sectiondescribes the soil removal and associated soil and ground-water sampling conducted at theformer UST location in chronological order. Figures 3 and 4 show the former UST location andsoil sampling locations and results through January 24 (Figure 3) and from January 24 throughFebruary 1 (Figure 4). Figure 5 shows ground-water sampling locations and results. Figure 6shows residual petroleum concentrations (in situ) remaining at the site.5.1 January 23, 2008ENW collected four (4) soil samples (identified as GS01 through GS04) from the top of eachend of the concrete mold (at four [4] feet bgs) to characterize the magnitude of impactsremaining at the former UST location (i.e. the “worst case” samples; see Figure 3 for samplinglocations).Subsequently, VEC dug two test pits immediately adjacent to the eastern and western ends ofthe concrete mold to determine the vertical extent of the soil impacts. Impacted soils wereencountered throughout both test pits (which were dug to approximately 10 feet bgs).Excavated soils were placed inside the concrete mold to help absorb the remainingproduct/ground water within the concrete mold before being loaded into trucks for disposal atHillsboro Landfill. Ground water was initially encountered in the test pits at about nine (9) feetbgs, and a soil sample was taken at that depth in each test pit (identified as GS05 and GS06).Creekside collected a ground-water sample from the eastern test pit.5.2 January 24, 2008ENW and VEC returned to the site to remove all impacted surface soils above the top of theconcrete mold (four [4] feet). Upon arriving at the site, ground water in the test pits had risenand stabilized at about five (5) feet bgs, and a small amount had again entered the “saddle” ofthe concrete mold. VEC proceeded to remove all visibly impacted surface soils surrounding thetank to a depth of four (4) feet. Impacted soils were loaded directly into trucks for disposal atHillsboro Landfill. Upon completion of the surface soil removal a total of nine (9) confirmationsamples (identified as GS07 through GS15) were collected from the sidewalls of the excavation(at three [3] feet bgs; see Figure 3 for locations). Floor samples were not collected at this timeas impacts deeper than three (3) feet were allowed to remain at the former UST location perODEQ authorization.5.3 January 25, 2008ENW mobilized to the site and collected a ground water sample from the western test pit.EVREN Northwest, Inc. 16 351-05009-06, Rev. 1, 3/17/08
  21. 21. As previously approved by ODEQ, arsenic-impacted soils stockpiled at the site (resulting fromprevious environmental cleanup activities at the site) were placed into the “saddle” of theconcrete mold to a depth of four (4) feet bgs (approximately 30 cubic yards). The remainder ofthe excavation was then backfilled with clean crushed rock to flush with the surrounding grade.Remaining arsenic-impacted stockpiled soils were transported offsite for disposal at HillsboroLandfill (under a separate permit from UST content-impacted soils). The arsenic stockpile wasobserved to be set on top of plastic sheeting. The plastic sheeting, as well as approximatelyfour (4)-inches of soil beneath the plastic sheeting was also transported offsite for disposal.Additionally, a large pile of arsenic-impacted building debris (concrete, rebar, etc.) wastransported to Hillsboro Landfill for disposal under the same permit. A total of approximately331 tons of arsenic-impacted materials were disposed of from the site.5.4 January 31, 2008After reviewing the laboratory analytical data from the “worst case” impacts remaining at theformer UST location (below four [4] feet), the ODEQ requested that additional soil removal takeplace along the northern and southern margins of the former tank concrete mold due to elevatedconcentrations of volatile chlorinated solvents (specifically trichloroethene [TCE]), which wereabove vapor intrusion screening values. VEC mobilized to the site and removed impacted soilsalong the southern side of the concrete mold; the impacted soils were directly loaded into atruck for disposal at Hillsboro Landfill. The excavation reached a depth of about five (5) feetbgs, where visibly impacted soils attenuated. ENW collected a total of four (4) confirmationsamples (identified as GS16 through GS19) from the floor and sidewalls of the excavation (seeFigure 4 for locations). After collecting the confirmation samples, the excavation was backfilledwith clean crushed rock.5.5 February 1, 2008VEC removed impacted soils along the northern side of the concrete mold; the impacted soilswere directly loaded into trucks for disposal at Hillsboro Landfill. The excavation reached adepth of about seven (7) feet bgs, when visibly impacted soils attenuated. ENW collected atotal of four (4) confirmation samples (identified as GS20 through GS23) from the floor andsidewalls of the excavation (see Figure 4 for locations). After collecting the confirmationsamples, the excavation was backfilled with clean crushed rock.EVREN Northwest, Inc. 17 351-05009-06, Rev. 1, 3/17/08
  22. 22. 6.0 ANALYTICAL RESULTSThis section presents the results of the soil and ground-water sampling activities associatedwith the UST decommissioning and soil removal activities described in this report.6.1 Characterization SamplingAs previously stated, initial characterization samples of the UST contents collected in Octoberand November 2007 indicated that the tank fluids were probably waste oil (based on analysis byanalytical method NWTPH-HCID), and contained low-level concentrations of BTEX,naphthalene, cis-1,2-dichloroethylene, TCE, and TMBs. The analytical results are presented inTable 1, following the text. Profiling conducted by Creekside showed the UST contents to be ahazardous waste.The initial characterization sample of impacted surface soils surrounding the tank (Sample FL-UST-SOIL-1) contained 29,900-milligrams per Kilogram (mg/Kg) DRO and 7,350-mg/Kg RRO,which exceeded the Soil Matrix Cleanup Level established for the site (500-mg/Kg DRO orRRO). Additionally, several of the VOCs detected in the tank fluid were present in the surfacesoils in excess of their most conservative RBC screening values (Table 1). ODEQ determinedthat the impacted surface soils, although considered hazardous waste under the “contained-in”rule, could be disposed at a Subtitle D landfill.3Based on these results, all subsequent samples (soil and ground water) were analyzed forDRO, RRO, and VOCs, unless indicated otherwise.6.2 Residual Subsurface Soil Characterization SamplingAfter the tank was removed, ENW collected four (4) soil samples (identified as GS01 throughGS04) from the top of each end of the concrete mold (at four [4] feet bgs). The soils werevisibly impacted with waste oil, and were collected to characterize the magnitude of the impactsremaining in the subsurface soils at the former UST location (the “worst case” samples).Additionally, two (2) samples (identified as GS05 and GS06) were collected from test pitscompleted at each end of the concrete mold (at nine [9] feet bgs) in order to delineate thevertical extent of the subsurface soil impacts.The subsurface soil characterization sampling locations are shown in Figure 3. The analyticalresults are presented in Table 1, after the text, and are described here:Petroleum Hydrocarbons (DRO and RRO): DRO was detected in GS01 through GS04 atconcentrations ranging from 6,000 mg/Kg to 38,000 mg/Kg, exceeding its soil matrix cleanuplevel of 500 mg/Kg. RRO was detected at concentrations ranging from 990 mg/Kg to 4,900mg/Kg, also exceeding the soil matrix cleanup level; however, the results were flagged by thelaboratory as not being indicative of motor oil.EVREN Northwest, Inc. 18 351-05009-06, Rev. 1, 3/17/08
  23. 23. DRO was detected in GS05 (collected from the western test pit) and GS06 (collected from theeastern test pit) at concentrations of 77 mg/Kg and 170 mg/Kg, respectively, which is below thesoil matrix cleanup level of 500 mg/Kg. RRO was not detected at or above the method reportinglimit in either of these analyzed samples. These results suggest that the vertical extent ofimpacted soils at the former UST location is limited to the top of the ground-water table (aroundfive [5] feet bgs).VOCs: Several of the VOCs (including BTEX constituents, butylbenzenes, dichlorobenzene,cis-1,2-dichloroethylene, propylbenzene, vinyl chloride, and TMBs) were detected at low levelswhich did not exceed their most stringent RBC screening values; however, TCE andnaphthalene were detected at elevated concentrations exceeding their most stringent RBCscreening values in samples GS01 and GS02.PAHs: The sample with the highest DRO concentration (sample GS02) was also analyzed forPAHs. Several of the PAHs were detected, all but one were below their mostly stringent RBCcleanup values: benz[a]anthracene was detected at 1.1 mg/Kg, which exceeds its moststringent RBC value of 0.15 mg/Kg.6.3 Surface Soil Confirmation SamplingAfter surface soils above the top of the concrete mold were removed (depth of removal was four[4] feet), nine (9) confirmation samples (identified as GS07 through GS15) were taken from thesidewalls of the excavation (at three [3] feet bgs) to characterize residual surface soils.Locations are shown in Figure 3. The analytical results are presented in Table 1 after the text,and are also described here:Petroleum Hydrocarbons (DRO and RRO): DRO and RRO were not detected at or above themethod reporting limit in any of the samples analyzed.VOCs: VOCs were not detected at or above the method reporting limit in any of the samplesanalyzed.Surface soil confirmations sampling results indicate no residual impacts in surface soilssurrounding the former UST.6.4 Subsurface Soil Confirmation SamplingAfter reviewing the laboratory analytical data from the “worst case” impacts remaining at theformer UST location (below four [4] feet), the ODEQ requested that additional soil removal takeplace along the northern and southern margins of the former tank’s concrete mold due toelevated concentrations of volatile chlorinated solvents (specifically TCE), which were abovevapor intrusion screening values. After additional excavation in these areas, ENW collected atotal of seven (7) confirmation samples (identified as GS16 through GS23, GS18 was notanalyzed) from the floor and sidewalls of the excavations. The subsurface soil confirmationEVREN Northwest, Inc. 19 351-05009-06, Rev. 1, 3/17/08
  24. 24. sampling locations are shown in Figure 4. The analytical results are presented in Table 1, afterthe text, and are described here:Petroleum Hydrocarbons (DRO and RRO): DRO and RRO were not detected at or above themethod reporting limit in any of the samples analyzed.VOCs: VOCs were not detected at or above the method reporting limit in any of the samplesanalyzed.Subsurface soil confirmations sampling results indicate residual impacts were removed from theareas excavated around the UST concrete mold. However, elevated concentrations ofpetroleum hydrocarbons exceeding RBC screening values and Soil Matrix Cleanup Levelsremain in subsurface soils adjacent to the former UST location (Figure 6); therefore, a riskbased assessment was performed and is described in Section 7.0.6.5 Ground Water Sampling ResultsTwo (2) ground water samples (USTEX-E and DW-080125) were collected at the former USTlocation, one from each of the test pits located on the eastern and western sides of the concretemold. Ground water originally entered the test pits at approximately nine (9) feet bgs, butstabilized overnight at approximately five (5) feet bgs. The ground-water sampling locations areshown in Figure 5. The analytical results are presented in Table 2, after the text, and aredescribed below:Petroleum Hydrocarbons (DRO and RRO): Only USTEX-E was analyzed for DRO and RRO.DRO was detected at 57,000 micrograms per Liter (µg/L), exceeding its screening level RBC of88 µg/L. RRO was detected at 9,000 µg/L, which also exceeds its screening level RBC of 290µg/L; however, the results were flagged by the laboratory as not being indicative of motor oil.VOCs: Only USTEX-E was analyzed for VOCs. Several of the VOCs (including BTEXconstituents, butylbenzene, cis-1,2-dichloroethylene, propylbenzenes, and TMBs) weredetected at low levels which did not exceed their respective most stringent RBC screeningvalues; however, TCE, naphthalene and 1,2,4-TMB were detected at elevated concentrationswhich exceeded their most stringent RBC screening values.PAHs: Only PW-080125 was analyzed for PAHs. Several PAHs were detected, but noneexceeded their most stringent RBC cleanup values.Results show that ground water in the immediate vicinity of the former UST was impacted.However, extensive ground-water monitoring has taken place at the site since the 1980’s, andODEQ granted closure to ground-water impacts at the site with a restriction on future use. Thisindicates that the ground-water impacts from the former UST are limited in nature and are notpresent beyond the immediate vicinity of the former UST (lateral extent or down-gradientmovement of the impacts have likely been hindered by the tight silts and clays in which theEVREN Northwest, Inc. 20 351-05009-06, Rev. 1, 3/17/08
  25. 25. impacts and upper most ground-water table are found). Based on this information anddiscussions with the ODEQ, the ground-water impacts in the immediate vicinity of the formerUST were not formally delineated as ODEQ is not requiring formal delineation based onprevious ground-water investigations conducted at the subject site.EVREN Northwest, Inc. 21 351-05009-06, Rev. 1, 3/17/08
  26. 26. 7.0 RISK-BASED ASSESSMENTWhere impacts to soil and ground water are present, the impacts must be evaluated using arisk-based approach described in ODEQ’s Risk Based Decision Making for the Remediation ofPetroleum Contaminated Sites (RBDM) guidance document, 2003 revision. Appendix A ofODEQ’s RBDM guidance document and its supplemental guidance materials provided by theagency provide pre-calculated risk-based concentrations (RBCs) which were developed asscreening levels for suspect sites, based on Oregon unacceptable additional risk criteria forcancer occurrence and for non-carcinogenic health impacts. The State of Oregon considersacceptable additional risk of cancer from contact with carcinogenic constituents at less than onein one million incidences, or for non-carcinogenic constituents, the constituent thresholdconcentration at which health impacts would occur. This section conducts a risk-basedassessment for soil and ground water, based on all available analytical data associated withresidual impacts from the UST, as described in this report.7.1 Identification of Constituents of InterestConstituents of interest (COIs) associated with UST release (profiled as waste oil) at the site arelisted below: GRO DRO RRO BTEX (benzene, toluene, ethylbenzene and xylenes) PAHs MTBE (methyl t-butyl ether) Iso-propylbenzene, n-propylbenzene, 1,2,4-TMB, and 1,3,5-TMB Hazardous metals (RCRA metals), lead, cadmium, chromium Chlorinated solvents PCBsThis Risk Assessment will follow the conservative approach of using the highest detectedconcentration of each analyte for each medium.7.2 Identification of Constituents of Potential ConcernConstituents were initially compared to conservative screening-level RBCs to identifyconstituents of potential concern (COPCs) in each medium. The residential screening-levelconcentrations of Appendix A of ODEQ’s RBDM guidance document and subsequent updatedguidance materials for both soil and ground water are used since this approach is the mostconservative method in assessing potential risk to human heath. The lowest residential RBC isused in the screening process regardless of whether a pathway is complete or not.EVREN Northwest, Inc. 22 351-05009-06, Rev. 1, 3/17/08
  27. 27. 7.2.1 SoilTable 1 summarizes the risk-screening of soil samples collected during the UST remedialactions. As described in the Section 6.0 of this document, benz[a]anthracene, naphthalene,DRO and RRO exceeded the screening level RBCs and are considered COPCs in soil.Many of the analyzed constituents (see Table 1) were not detected above their respectiveanalytical method detection limits; however those detection limits exceed the risk-basedscreening concentrations. ODEQ does not require cleanup for petroleum constituents that arenot detected by the department-specified analytical methods if standard method detection limitsare met. Therefore, these constituents in soils will not be further addressed.It should also be noted that ODEQ does not provide a RBC for RRO (except for mineral oil)because of the wide variation in compositions, and therefore the agency regulates RRO impactsto soil and ground water by analyses of associated constituents. 57.2.2 Ground WaterTable 2 summarizes the risk screening of the two (2) ground-water samples collected from thetest pits adjacent to the former UST location. As described in the Table and in Section 6.0 ofthis document, naphthalene, TCE, 1,2,4-TMB, DRO and RRO exceeded the screening levelRBCs and are considered COPCs in ground water.7.3 Conceptual Site Model7.3.1 Media of ConcernSoil and ground water are impacted at the former UST location. Surface soils (defined as lessthan three [3]-foot depth) were impacted from overspill from the top of the tank; however, theimpacts in the surface soils were effectively remediated by excavation as evidenced byconfirmation sampling (Section 6.3), and do not contain any COPCs. Subsurface soils (definedas greater than 3-foot depth) are impacted with the COPCs listed above (Section 7.2.1).Therefore surface and subsurface soils and ground water are the media of concern. As surfacesoils do not contain any COPCs, they will not be carried through the remainder of thisassessment.7.3.2 Land Use and Ground Water Use – Potential ReceptorsThe site is zoned Light Industrial (LI) by the City of Sherwood, which precludes residentialdevelopment in the future. Additionally, the site is listed as a CERCLIS site with the EPA andan ECSI site with the ODEQ due to extensive heavy metal contamination. ODEQ has restrictedany residential development at the site, and has required a paved cap across the surface of thesite to prevent movement of and/or dermal contact with any soils at the site.As the site is currently vacant and will likely be redeveloped in the future, construction andexcavation workers may be exposed to dermal contact with impacted subsurface soils.5 ODEQ. 2003. RBDM guidance document, Section 3.1.6.3. September.EVREN Northwest, Inc. 23 351-05009-06, Rev. 1, 3/17/08
  28. 28. Additionally, although the entire site will reportedly be paved, this assessment willconservatively consider possible exposure of occupational workers to surface soils, sinceexterior conditions may change in the future. Therefore, the potential receptors includeoccupational workers, construction workers, and excavation workers. It is assumed that thesereceptors are conservative with respect to consideration of the occasional site visitor.Ground water is not used for drinking water at the site. No domestic wells are located in thevicinity of the subject property. Additionally, ODEQ has determined that there is no beneficialuse of shallow ground water in the vicinity of the site and a ground-water use restriction will beplaced on the subject site. The City of Sherwood supplies water to residents who live within theCity limits. Therefore, the ground-water pathway will not be included in this risk assessment.7.3.3 Pathways of ConcernAn exposure pathway is the course a constituent takes from a source to an exposed population.Exposure pathways include four elements: (1) the source of contamination; (2) the means bywhich a constituent will be released, retained, or travel in a given medium (e.g., air or groundwater); (3) a point of potential contact with a receptor; and (4) the means by which contact willoccur (e.g., inhalation, ingestion). If any of these elements are missing, the pathway isconsidered incomplete. Table 7-1 presents a summary of the pathway analysis for humanreceptors.EVREN Northwest, Inc. 24 351-05009-06, Rev. 1, 3/17/08
  29. 29. Table 7-1. Summary of Pathway Analysis for Human Receptors Potentially Exposure Route, Medium and Exposure Pathway Exposed Reason for Selection or Exclusion Point Considered Population Soil Occupational Leaching to ground water with subsequent Ground water is not used as a drinking water No worker ingestion source in the vicinity of the site. Occupational Inhalation of volatiles from impacted soil YES Subsurface soils contain volatile constituents. worker (outdoor air) Occupational Inhalation of volatiles from impacted soil YES Subsurface soils contain volatile constituents. worker intruding into building (indoor air) Occupational Even though surface soils are no longer worker Direct ingestion, inhalation of volatiles and impacted and the site will be completely YES dermal contact with soil paved, this assessment will conservatively address this pathway. Construction Direct ingestion, inhalation of volatiles and YES Impacts are present in subsurface soils. Worker dermal contact with soil Excavation Direct ingestion, inhalation of volatiles and YES Impacts are present in subsurface soils. Worker dermal contact with soil Ground Water Occupational Ground water is not used for drinking water in Ingestion of impacted ground water No worker the vicinity of the site. Occupational Inhalation of volatiles from impacted ground Shallow ground water impacts are present on YES worker water (outdoor air) the subject property. Occupational Inhalation of volatiles from ground water YES Ground water contains volatile constituents. worker intruding into building (indoor air) Excavation Direct ingestion, inhalation of volatiles and YES Shallow ground water is impacted. Worker dermal contact with ground water7.3.4 Developed Conceptual Site ModelBased on the above discussion, a conceptual site model has been developed for the formerUST location (Figure 7).7.3.5 Evaluation of COPCsSince COPCs were identified by the initial screening, they are further screened by identifiedcomplete exposure pathways.7.3.5.1 Subsurface SoilTable 7-2, below, further evaluates the COPCs based on the identified complete exposurepathways for subsurface soil. The table indicates that the CPOCs identified in subsurface soil(benz[a]anthracene, naphthalene, DRO and RRO) do not present an unacceptable health riskby the identified complete exposure pathways, and are not constituents of concern at in soilssurrounding the former UST.As mentioned above, ODEQ does not provide a RBC for RRO and regulates RRO impacts byanalyses of associated constituents. As such, all associated constituents have beenappropriately evaluated in this risk assessment and do not present an unacceptable health riskEVREN Northwest, Inc. 25 351-05009-06, Rev. 1, 3/17/08
  30. 30. by the identified complete exposure pathways; therefore, RRO itself does not present anunacceptable health risk by the identified complete exposure pathways. Table 7-2. Risk Evaluation of COPCs Identified in Subsurface Soil Risk-Based Concentrations (SOIL) Contaminated Medium mg/Kg (ppm) Volatilization to Vapor Intrusion Soil Ingestion, Dermal Contact, and Inhalation Lowest Exposure Pathway Maximum Soil Outdoor Air into Buildings Applicable RBC COC? Concentration RBCss RBCso RBCsi (Soil) Receptor Scenario Occupational Construction Worker Excavation Worker Occupational OccupationalDirect or Indirect Pathway (see notes) DC DC DC IV IVContaminant of Concern Note mg/Kg (ppm) Note Note Note Note Note mg/Kg (ppm) Y/N Benz[a]anthracene c, nv 1.1 2.7 21 >Csat 590 >Csat - NV - NV 2.7 N Naphthalene nc, v 24 770 >Csat 710 >Csat 20,000 >Csat 940 3,400 710 N DRO nc, nv 17,000 70,000 23,000 - >Max - >Max - >Max 23,000 N RRO nc, nv 2,400 - >Max - - >Max - >Max - >Max - NNotes:— = not applicable.mg/Kg = milligram per kilogram.c = carcinogenicnc = noncarcinogenicv = volatilenv = nonvolatileDRO = diesel-range organics.RRO = residual-range organics.Bolded concentrations exceed lowest Pathway Specific Risk-Based7.3.5.2 Ground WaterTable 7-3, below, further evaluates the COPCs based on the identified complete exposurepathways for ground water. The Table indicates that the COPCs identified in ground water(naphthalene, TCE, 1,2,4-TMB, DRO and RRO) do not present an unacceptable health risk bythe identified complete exposure pathways, and are not constituents of concern in ground waterin the area of the former UST. Table 7-3. Risk Evaluation of COPCs Identified in Ground Water Risk-Based Concentrations (GROUND WATER) Contaminated Medium µg/L (ppb) Volatilization to Vapor Intrusion Maximum GW in Excavation Lowest Applicable Exposure Pathway Outdoor Air into Buildings Ground Water RBC COC? Concentration RBCwo RBCwi RBCwe (Groundwater) Construction & Receptor Scenario Occupational Occupational Excavation WorkerDirect or Indirect Pathway (see notes) IV IV DSContaminant of Concern Note µg/L (ppb) Note Note Note µg/L (ppb) Y/N Naphthalene nc, v 100 540,000 350,000 680 680 N Trichloroethene c, v 2.4 650 110 130 110 N Trimethylbenzene, 1,2,4- nc, v 67 270,000 51,000 1,300 1,300 N DRO nc, nv 57000 - >S - >S - >S --- N RRO nc, nv 9000 - >S - >S - >S --- N— = not applicable.ug/L = micrograms per Literc = carcinogenicnc = noncarcinogenicv = volatilenv = nonvolatileDRO = diesel-range organics.RRO = residual-range organics.7.4 Evaluation of Risk to the EnvironmentNo sensitive environmental lands were identified at the subject property. However, Rock Creekand an associated wetlands area are present immediately to the northeast of the site. Asmentioned earlier, ground-water monitoring has been taking place at the site since the 1980’sand ODEQ agreed that ground water was not a media of concern assuming formal restrictionsEVREN Northwest, Inc. 26 351-05009-06, Rev. 1, 3/17/08
  31. 31. of future ground-water use. This indicates that the ground water impacts from the former USTare limited in nature and are not present beyond the immediate vicinity of the former UST(lateral extent or down-gradient movement of the impacts have likely been hindered by the tightsilts and clays in which the impacts and upper most ground-water table are found). Based onthis information and discussion with ODEQ, the ground-water impacts in the immediate vicinityof the former UST were not formally delineated as ODEQ is not requiring formal delineationbased on previous ground-water investigations conducted at the subject site.Since the former tank location will be capped as part of the proposed development, residualpetroleum-impacted soil (the extent of which is shown in Figure 6) should not present anunacceptable risk to the environment.7.5 DiscussionBased on the results of this conservative risk assessment, none of the COPCs (in any medium)have been determined to be a constituent of concern at the property. Therefore, the COPCs atthe former UST location do not present an unacceptable health risk by the identified completeexposure pathways.EVREN Northwest, Inc. 27 351-05009-06, Rev. 1, 3/17/08
  32. 32. 8.0 CONCLUSIONS AND RECOMMENDATIONSAn approximate 8,000-gallon capacity UST was discovered in October 2007 during demolitionof the concrete floor slab of the tannery facility building at the subject site. Characterization ofthe tank contents and soil above the tank indicated that the tank was most likely used as awaste oil tank and that the residual contents required management as a hazardous waste.In December 2007, fluid was removed from the UST and properly disposed. Lowering of thetank contents exposed debris within the tank; possibly introduced during demolition activitiesoccurring around the tank. In January 2008, impacted soil around the tank was removed anddisposed at Hillsboro Landfill. At the same time, access to the tank interior was created andfluids were removed, as were solid debris and sludge. The tank was subsequently cleaned andtransported off-site for recycling. Exposure, cleaning and removal activities showed the tank tobe corroded and leaking. After removal, soils in the tank excavation were observed to beimpacted with oil.Soil and ground-water assessment, impacted soil removal and soil confirmation samplingactivities ensued. A risk-based assessment of residual soil and ground water impacts showedthey pose no risk to human health or the environment.As previously approved by ODEQ, previously stockpiled arsenic-impacted soil was used tobackfill the UST excavation, to within four (4)-feet of the ground surface (approximately 30 cubicyards). The balance of the stockpile was then transported to Hillsboro Landfill.ENW recommends that a Soil and Ground Water Management Plan which describesappropriate handling and disposal procedures be developed in the event that residual impactedsoils and/or ground water are disturbed in the future,. ENW further recommends that ODEQgrant regulatory closure to LUST File No. 34-07-1896 and issue a “No Further Action Required”letter. The property owner is required to keep a copy of this report and regulatory closure letterfor ten years after he/she sells or otherwise transfers the property.EVREN Northwest, Inc. 28 351-05009-06, Rev. 1, 3/17/08
  33. 33. 9.0 LIMITATIONSThe scope of this report is limited to observations made during on-site work; interviews withknowledgeable sources; and review of readily available published and unpublished reports andliterature. As a result, these conclusions are based on information supplied by others as well asinterpretations by qualified parties.The focus of the site closure does not extend to the presence of the following conditions unlessthey were the express concerns of contacted personnel, report and literature authors or thework scope. 1. Naturally occurring toxic or hazardous substances in the subsurface soils, geology and water, 2. Toxicity of substances common in current habitable environments, such as stored chemicals, products, building materials and consumables, 3. Contaminants or contaminant concentrations that are not a concern now but may be under future regulatory standards, 4. Unpredictable events that may occur after ENW’s site work, such as illegal dumping or accidental spillage.There is no practice that is thorough enough to absolutely identify the presence of all hazardoussubstances that may be present at a given site. ENW’s investigation has been focused only onthe potential for contamination that was specifically identified in the SOW. Therefore, ifcontamination other than that specifically mentioned is present and not identified as part of alimited SOW, ENW’s environmental investigation shall not be construed as a guaranteedabsence of such materials. ENW has endeavored to collect representative analytical samplesfor the locations and depths indicated in this report. However, no sampling program canthoroughly identify all variations in contaminant distribution.We have performed our services for this project in accordance with our agreement andunderstanding with the client. This document and the information contained herein have beenprepared solely for the use of the client.ENW performed this study under a limited scope of services per our agreement. It is possible,despite the use of reasonable care and interpretation, that ENW may have failed to identifyregulation violations related to the presence of hazardous substances other than thosespecifically mentioned at the closure site. ENW assumes no responsibility for conditions thatwe did not specifically evaluate or conditions that were not generally recognized asenvironmentally unacceptable at the time this report was prepared.EVREN Northwest, Inc. 29 351-05009-06, Rev. 1, 3/17/08

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