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.

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. 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. CONTENTS
TABLES AND FIGURES.............................................................................................................................. 1
ACRONYMS AND ABBREVIATIONS ......................................................................................................... 2
EXECUTIVE SUMMARY .............................................................................................................................. 3
1.0 INTRODUCTION.............................................................................................................................. 5
1.1 Background ....................................................................................................................... 5
1.2 Purpose.............................................................................................................................. 6
1.3 Scope of Work ................................................................................................................... 6
2.0 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 ....................................................................................................... 9
3.0 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................................................................................. 13
4.0 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................................................................................................................... 14
5.0 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.............................................................................................................. 17
6.0 ANALYTICAL RESULTS .............................................................................................................. 18
6.1 Characterization Sampling............................................................................................. 18
6.2 Residual Subsurface Soil Characterization Sampling ................................................ 18
6.3 Surface Soil Confirmation Sampling ............................................................................ 19
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4. 6.4 Subsurface Soil Confirmation Sampling ...................................................................... 19
6.5 Ground Water Sampling Results................................................................................... 20
7.0 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 ....................................................................................................................... 27
8.0 CONCLUSIONS AND RECOMMENDATIONS............................................................................. 28
9.0 LIMITATIONS ................................................................................................................................ 29
APPENDICES
APPENDIX A ODEQ UST REGISTRATION, DECOMMISSIONING NOTIFICATION, CHECKLIST AND
REPORT
APPENDIX B SITE PHOTOGRAPHS
APPENDIX C LABORATORY ANALYTICAL REPORTS
APPENDIX D SOIL MATRIX SCORE SHEET AND CHECKLIST
APPENDIX E WASTE RECEIPTS
EVREN Northwest, Inc. iv 351-05009-06, Rev. 0, 3/17/08

5. TABLES AND FIGURES
Table Location
3-1 Analytical Methods ............................................................................................... Section 4
7-1 Summary of Pathway Analysis for Human Receptors.......................................... Section 5
7-2 Risk Evaluation of Identified COPCs in Soil......................................................... Section 5
7-3 Risk Evaluation of Identified COPCs in Ground Water ........................................ Section 5
1 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 ........................................................................................................................... 1
Site Plan........................................................................................................................................ 2
Sampling Location Diagram, Soil (as of 1/24/2008)...................................................................... 3
Sampling Location Diagram, Soil (as of 2/1/2008)........................................................................ 4
Sampling Location Diagram, Ground Water ................................................................................. 5
Residual Petroleum Concentrations (In Situ) Remaining at the Site ............................................ 6
Conceptual Site Model (in text)..................................................................................................... 7
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6. ACRONYMS AND ABBREVIATIONS
API American Petroleum Institute
bgs below ground surface
BTEX benzene, tolulene, ethylbenzene and total xylenes
CERCLIS Comprehensive Environmental Response, Compensation and Liability
Information System
COIs constituents of interest
COPCs constituents of potential concern
Creekside Creekside Environmental Consulting
DRO diesel-range organics
ENW EVREN Northwest, Inc.
EPA U. S. Environmental Protection Agency
GRO gasoline-range organics
LUST Leaking Underground Storage Tank
mg/Kg milligrams/Kilogram
µg/L micrograms per Liter
NRC NRC Environmental Services
NWTPH-Dx Northwest analytical method for diesel and oil
NWTPH-HCID Northwest analytical method for hydrocarbon identification
ODEQ Oregon Department of Environmental Quality
OARs Oregon Administrative Rules
OVM organic vapor monitor
ORELAP Oregon Environmental Laboratory Accreditation Program
OWRDGD Oregon Water Resources Department Grid Database
PAHs polynuclear aromatic hydrocarbons
PCBs polychlorinated biphenyls
PSC Philip Services Corporation
RBCs risk-based concentrations
RBDM Risk-Based Decision Making for Remediation of Petroleum Contaminated
Sites, ODEQ September 2003 Guidance Document
RCRA Resource Conservation and Recovery Act
RRO residual (oil) range organics
SOW scope of work
TCE trichloroethylene
TMB trimethylbenzene
USGS United States Geological Survey
UST underground storage tank
VEC Varchan Environmental Construction
VOCs volatile organic compounds
WCM West Coast Marine Cleaning, Inc.
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7. EXECUTIVE SUMMARY
The former Frontier Leather Company property, located at 15104 SW Oregon Street in
Sherwood, Oregon, is undergoing Oregon Department of Environmental Quality-directed
environmental cleanup related to historical tannery operations conducted at the site. In October
2007, an approximate 8,000-gallon capacity underground storage tank was discovered during
demolition 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 most
likely used as a waste oil tank and that the residual contents required management as a
hazardous waste; impacted soils were approved for disposal at a Subtitle D landfill. A work plan
for decommissioning the tank was prepared for and approved by the Oregon Department of
Environmental Quality.
In December 2007 and January 2008, fluid and solid debris were removed from the tank and
taken to appropriate disposal facilities. Following removal of the tank contents, the tank was
thoroughly cleaned, removed from the ground with a crane, and transported off-site for recycling
in accordance with national standards of practice. Upon removal, the tank was observed to be
attached with metal straps to a concrete mold around the bottom half of the tank, designed to
act 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 ground
surface. Soils surrounding the tank were visibly impacted. Ground water was encountered at
approximately five (5) feet below ground surface.
Removal of the tank also revealed residual impacted soils; characterization samples
representative of “worst case” impacts were collected. Subsequently, over the course of a week
and with Oregon Department of Environmental Quality involvement, impacted soils were
removed, ground-water samples were collected from test pits located at either end of the former
tank location and confirmation soil samples were collected. Excavated soils were placed
directly 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 ground
surface (approximately 30 cubic yards). The balance of the stockpile was then transported to
Hillsboro 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.)
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8. • Constituents of potential concern in ground water were naphthalene,
trichloroethene, 1,2,4- trimethylbenzene, and diesel- and residual-range organics
A risk-based assessment was performed for the constituents commonly associated with waste
oil. A conceptual model was developed to identify complete exposure pathways from the
release source to human receptors. The potential receptors were identified as occupational
workers and excavation/trench workers. Pathways identified as complete were volatilization into
interior and exterior air for occupational workers and dermal contact-incidental ingestion for
excavation workers and construction workers. Based on the conceptual model performed as
part of the risk-based assessment, none of the constituents of potential concern in either
subsurface soils or ground water is likely to cause an unacceptable health risk by the identified
complete exposure pathways. Therefore no additional investigation or remediation is required
at this time.
ENW recommends that a Soil and Ground Water Management Plan which describes
appropriate handling and disposal procedures be developed in the event that residual impacted
soils and/or ground water are disturbed in the future. ENW further recommends that ODEQ
grant 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 letter
for ten years after he/she sells or otherwise transfers the property.
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9. 1.0 INTRODUCTION
The former Frontier Leather Company property, located at 15104 SW Oregon Street in
Sherwood, Oregon (subject site; Figure 1), is undergoing Oregon Department of Environmental
Quality (ODEQ)-directed environmental cleanup related to historical tannery operations
conducted at the site. This report describes the decommissioning of an underground storage
tank (UST) discovered during site demolition and the risk-based assessment of associated
impacted soil and ground water.
This work was performed in accordance with the Workplan for Underground Storage Tank
Decommissioning 1 , which was approved by the ODEQ in January of 2008. Creekside
Environmental Consulting (Creekside) requested EVREN Northwest, Inc. (ENW) to collaborate
on the project and prepare this report.
1.1 Background
The former Frontier Leather Company, which began operating a tannery at the subject site in
1947, 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 have
taken place at the subject site. A comprehensive history of the site is described in a March
2006 progress report compiled by Creekside 2 .
In October 2007, an abandoned, approximately 8,000-gallon capacity UST was identified during
demolition of the concrete floor slab of the tannery facility building (the UST was originally
thought to be 10,000 gallons in capacity, but exposure by excavation showed that it was
smaller).
Initial characterization samples of the UST contents indicated that the tank contained waste oil
(based on analysis by analytical method NWTPH-HCID [hydrocarbon identification]); analytical
results are presented in Table 1, following the text. Detections included low-level
concentrations 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 conducted
by Creekside showed the UST contents to be hazardous waste.
During initial removal of the fluids from the tank, large quantities of solid debris (described in
detail in Section 3.1 of this report) including concrete rubble, soil, wood and metal waste were
1
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.
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10. discovered inside the tank (the presence of this solid debris was unknown when the workplan
was submitted and approved). Since demolition activities were underway at the site, it is likely
that 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, causing
an “overspill” out of the access ports in the top of the tank, impacting surface soils in the
immediate vicinity of the tank. The release was reported to the ODEQ’s Leaking Underground
Storage Tank (LUST) Program, and was assigned LUST File No. 34-07-1896. Based on
analytical data for the impacted surface soils, ODEQ permitted these soils to be transported and
disposed at a Subtitle D landfill. 3
This report specifically addresses the UST decommissioning and related activities for the above
referenced LUST file. All other work at the site is being performed for and directed by the
ODEQ’s Cleanup Program.
1.2 Purpose
The purpose of the project was to decommission the UST in a safe and appropriate manner
following applicable guidance and regulations and to properly address associated impacted soil
and ground water, with a goal of obtaining regulatory closure for the LUST file at the site from
ODEQ.
1.3 Scope of Work
ENW 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.
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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.
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12. 2.0 SITE SETTING
2.1 Location and Description
The former Frontier Leather Company property is located at 15104 SW Oregon Street in a
commercial-residential district of the city of Sherwood, Oregon (Figure 1). The site is bounded
by a wetlands area to the north, SW Oregon Street to the east and south, and railroad tracks to
the west (see Figure 2). Commercial properties are present further to the north and west, and a
single family residential neighborhood is present to the east and south, across SW Oregon
Street. 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 and
undeveloped. The UST which is the subject of this report was located in the western portion of
the property, beneath the northern portion of the former tannery building (Figure 2).
2.2 Topography
The subject site is located within the U.S. Geological Survey (USGS) Sherwood 7.5-minute
quadrangle, 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. Rock
Creek flows northward and discharges to the Tualatin River, located approximately two (2) miles
to the north of the subject property.
2.3 Geologic Setting
The subject property is located in the Tualatin River Basin of northwestern Oregon. The
Tualatin River Basin is a structural depression between the Chehalem Hills to the south, Oregon
Coast 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 streams
have modified the structural depression of the basin. Sediments within the basin fill include
erosional 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 flood
waters deposited large volumes of sediment throughout the Basin, and at times were dammed
up within the basin before being released to down-gradient areas.
During the soil removal activities described in this report, soils encountered beneath the site
consisted 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) to
determine subsurface conditions in the vicinity of the subject site. Several monitoring wells
completed at the site encountered silty clay soils below fill materials to an approximate depth of
11 feet, which were in turn underlain by silt, silty sand, and sand to 18 feet bgs. At a
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13. neighboring site, monitoring well logs indicate that silty sand directly underlies the surficial fill
materials to a depth of 25 feet, which in turn overlies at least five (5) feet of weathered silty clay.
2.4 Hydrogeologic Setting
2.4.1 Surface Water
Topographic mapping by the USGS indicates that the site slopes gently northeastward toward
Rock 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. 4
2.4.2 Ground Water
Ground water was encountered during the decommissioning activities at around nine (9) feet
bgs, rising to a depth of approximately five (5) feet in excavations. Based on hydrogeologic
studies at the site, ground-water flow direction should be toward the northeast.
4
City of Portland’s website: www.portlandmaps.com
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14. 3.0 METHODS AND PROCEDURES
The 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 UST
decommissioning and associated work; following sections describe the work and findings. A
photographic log of all the field work is presented in Appendix B.
3.1 UST Decommissioning
Decommissioning of the UST system was based on the procedures referenced in the following
documents:
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 and
surrounding 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 tank
was determined to be a hazardous waste (requiring disposal at an appropriate hazardous waste
facility). 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.
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15. 3.2 Soil and Ground Water Sampling
After the UST was removed, residual oil impacts were indicated in the tank excavation. Section
5.0 describes the remedial activities and summarizes the collection of soil and ground-water
samples. Sampling methods and procedures are described here.
3.2.1 Soil
All soil samples were collected from freshly excavated soils in the excavator bucket and
transferred with fresh Nitrile gloves into sample containers provided by the laboratory.
Headspace within the containers was minimized before sealing. Samples were also placed in
Ziploc bags for headspace screening with an organic vapor monitor (OVM) and field
identification. 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 until
delivered to the laboratory under chain-of-custody protocols.
Additionally, samples for volatile organic compound (VOC) analyses were collected according to
the proscribed procedures of U.S. Environmental Protection Agency (EPA) Method 5035A,
using sampling kits provided by the laboratory.
3.2.2 Ground Water
Ground-water samples were collected using a clean disposable plastic bailer and immediately
transferred to laboratory-supplied bottles. Ground-water samples to be analyzed for diesel
range organics (DRO) were collected in 500-milliliter glass amber bottles preserved with
aliquots of hydrochloric acid. Ground-water samples to be analyzed for VOCs were collected in
volatile organic analysis vials preserved with aliquots of hydrochloric acid, prepared by the
laboratory. Water samples collected for polynuclear aromatic hydrocarbons (PAHs) analysis
were collected in unpreserved one (1)-liter brown glass containers (Boston Rounds). The
sample containers were filled completely and immediately sealed to eliminate headspace. 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 until delivered to the laboratory
under chain-of-custody protocols.
3.2.3 Analytical Methods
Laboratory 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 Total
Petroleum 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 for
VOCs by EPA Method 8260; for RCRA metals by EPA Method 200.8, and for polychlorinated
biphenyls (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 also
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16. analyzed for PAHs by EPA method 8270 and by method NWTPH-HCID, as required by the
ODEQ 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 concentration
3.3 Cleanup Standards
3.3.1 Soil Matrix Cleanup Standards
The Oregon Administrative Rules (OARs) 340-122-0205 through 0360 (Soil Matrix Cleanup
Rules) were developed as part of the UST Cleanup Rules. However, the ODEQ’s Risk-Based
Decision Making for the Remediation of Petroleum-Contaminated Sites (RBDM) guidance
document (2003 revision) states that the Soil Matrix Cleanup levels developed under those rules
are 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 being
remediated under the Hazardous Substance Remedial Action Rules.
The Soil Matrix Cleanup Rules permit soil impacts from petroleum hydrocarbons to be cleaned
up by setting standards based on site conditions. The cleanup levels are determined for the site
by inputting environmental parameters with site-specific values. The values used in determining
the 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 receptors
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17. • Number of potential receptors
The Soil Matrix score appropriate for the site was determined to be 25, indicating Level II
cleanup 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 Checklist
for the site are presented in Appendix D.
3.3.2 Risk-Based Decision Making
Where Soil Matrix Cleanup standards are not met, ODEQ allows closure using a risk-based
approach described in the agency’s RBDM guidance document, 2003 revision. Risk-based
concentrations (RBCs) tabulated in Appendices A and J of the RBDM guidance document were
developed as screening levels for suspect sites based on Oregon unacceptable additional risk
criteria for cancer occurrence and for non-carcinogenic health impacts. The State of Oregon
considers acceptable additional risk of cancer from contact with carcinogenic constituents at
less than one in one million incidences, or, for non-carcinogenic constituents, below the
constituent threshold concentration at which health impacts would occur. Appendix J of the
RBDM guidance document additionally states that there is no reason the RBDM approach
should be limited to petroleum hydrocarbons, and the approach described [in the guidance
document] may be generalized to chemicals other than petroleum hydrocarbons. Residential
standards were used for initial ‘conservative’ screening.
3.3.3 Background Concentrations (Metals)
Metals were also compared to default background concentrations in soil determined by the
ODEQ’s Oregon Toxicology Work Group.
3.4 Waste Management and Disposal
All waste generated during the UST decommissioning and associated soil remediation by
removal was properly handled and disposed. Disposal receipts are included in Appendix E and
document 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.
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18. 4.0 UST DECOMMISSIONING
4.1 UST Description
The UST was oriented east to west and was determined to be approximately 21.5 feet in length
and eight (8) feet in diameter (approximately 8,000 gallons in capacity). The top of the tank was
approximately flush with the surrounding grade (after removal of all onsite structures and
concrete 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, the
tank was observed to be set in a concrete mold (present only around the bottom half of the
tank), to which the tank was strapped, acting as a “dead man” weight to keep the tank firmly in
place under potential buoyant conditions. The top of the concrete mold was measured at
approximately four (4) feet bgs. Figure 3 presents the layout of the former UST position.
4.2 Fluid Removal
On December 18, 2007, Philip Services Corporation (PSC) removed a total of 3,000-gallons of
fluid (profiled as waste oil) from the tank using a vacuum truck. As the level of product in the
tank lowered, it was discovered that a significant amount of solid debris was present in the
bottom half of the tank. Upon discovery of the solid debris in the tank, no further product
removal was performed that day. PSC disposed of the removed fluid at their treatment facility in
Tacoma, Washington.
On December 27, 2007, NRC Environmental Services (NRC) removed the remaining liquid
product inside the tank (1,340 gallons) using a vacuum truck. NRC disposed of the removed
fluid at the PSC treatment facility in Tacoma, Washington.
4.3 UST Exposure by Soil Removal
On January 21, 2008, Varchan Environmental Construction (VEC) removed the surface soils
overlying the top of the UST, so it could be accessed for cleaning. The overburden (which had
previously been sampled and shown to be impacted; see Section 6.1) was placed directly into
trucks as it was excavated and transported to Waste Management's Subtitle D landfill in
Hillsboro, Oregon. Upon exposure a large hole was observed in the top of the west end of the
tank, and VEC further enlarged the hole in order to facilitate access to the tank’s interior for
solid debris removal and cleaning. It was observed that the tank was approximately half full of
oily fluid. Since fluids had been previously removed from the UST as described above, it was
determined that, given the shallow depth of ground water (approximately 5 feet), ground water
was likely entering the tank through its various corroded holes.
4.4 UST Cleaning
On January 21 and 22, 2008, West Coast Marine Cleaning, Inc. (WCM) was contracted to
remove the remaining oily fluids, sludge, and solid debris from the tank, and to clean the inside
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19. of the tank. WCM utilized confined space procedures. Approximately 2,500 gallons of tank
fluids (profiled as waste oil) were pumped using a vacuum truck and taken to PSC’s treatment
facility in Tacoma, Washington. The solid debris was removed using a Guzzler vacuum truck
connected to an air-tight vacuum box (in which the solids were collected). A total of
approximately 13 tons of solid debris (profiled as oil-contaminated debris and managed as
hazardous waste) was removed from the tank and taken to US Ecology’s treatment facility in
Grand View, Idaho.
While removing the solid debris from inside the tank, several approximate 15 to 20-gallon steel
drums were found inside the tank. Given their shape and size, they would have fit inside the
access ports in the top of the tank. The drums were thoroughly corroded, and were likely
placed inside the tank many years ago (the drums may be a likely source of the chlorinated
solvents found inside the tank). All large solid debris found in the tank was placed inside a drop
box lined with plastic sheeting (along with all hoses and equipment contaminated during the
product/debris removal).
Once fluids and debris were removed, the UST was cleaned by 1) hand scraping the tank
interior to remove as much sludge as possible, 2) rinsing the tank interior with degreaser cutter
stock (diesel), and 3) rinsing the tank interior with fresh water and soap rinse. All remaining
sludge in the bottom of the tank (along with all rinsate generated during the tank cleaning) was
removed 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. VEC
excavated additional surface soils surrounding the top of the tank in order to relieve the tank
and allow for removal. The soils were observed to be impacted consistent with previously
removed 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 tank
overnight. The crane was used to lift the tank out of its position and tilt the tank slightly in order
to let the ground-water drain from a hole in the bottom of the tank. The tank was placed on a
trailer 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-going
holes. 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 observed
through several holes in the side of the concrete mold. Waste oil product was observed to be
seeping into the mold from soils surrounding the top of the mold. The concrete dead-man was
left in place. See Appendix A for State UST Decommissioning Checklist and Report forms.
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20. 5.0 IMPACTED SOIL REMOVAL AND ASSOCIATED SOIL AND
GROUND-WATER SAMPLING
Removal of the UST exposed visibly impacted soil in the tank excavation. This section
describes the soil removal and associated soil and ground-water sampling conducted at the
former UST location in chronological order. Figures 3 and 4 show the former UST location and
soil sampling locations and results through January 24 (Figure 3) and from January 24 through
February 1 (Figure 4). Figure 5 shows ground-water sampling locations and results. Figure 6
shows residual petroleum concentrations (in situ) remaining at the site.
5.1 January 23, 2008
ENW collected four (4) soil samples (identified as GS01 through GS04) from the top of each
end of the concrete mold (at four [4] feet bgs) to characterize the magnitude of impacts
remaining at the former UST location (i.e. the “worst case” samples; see Figure 3 for sampling
locations).
Subsequently, VEC dug two test pits immediately adjacent to the eastern and western ends of
the concrete mold to determine the vertical extent of the soil impacts. Impacted soils were
encountered throughout both test pits (which were dug to approximately 10 feet bgs).
Excavated soils were placed inside the concrete mold to help absorb the remaining
product/ground water within the concrete mold before being loaded into trucks for disposal at
Hillsboro Landfill. Ground water was initially encountered in the test pits at about nine (9) feet
bgs, 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, 2008
ENW and VEC returned to the site to remove all impacted surface soils above the top of the
concrete mold (four [4] feet). Upon arriving at the site, ground water in the test pits had risen
and stabilized at about five (5) feet bgs, and a small amount had again entered the “saddle” of
the concrete mold. VEC proceeded to remove all visibly impacted surface soils surrounding the
tank to a depth of four (4) feet. Impacted soils were loaded directly into trucks for disposal at
Hillsboro Landfill. Upon completion of the surface soil removal a total of nine (9) confirmation
samples (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 time
as impacts deeper than three (3) feet were allowed to remain at the former UST location per
ODEQ authorization.
5.3 January 25, 2008
ENW mobilized to the site and collected a ground water sample from the western test pit.
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21. As previously approved by ODEQ, arsenic-impacted soils stockpiled at the site (resulting from
previous environmental cleanup activities at the site) were placed into the “saddle” of the
concrete mold to a depth of four (4) feet bgs (approximately 30 cubic yards). The remainder of
the 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 Hillsboro
Landfill (under a separate permit from UST content-impacted soils). The arsenic stockpile was
observed to be set on top of plastic sheeting. The plastic sheeting, as well as approximately
four (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.) was
transported to Hillsboro Landfill for disposal under the same permit. A total of approximately
331 tons of arsenic-impacted materials were disposed of from the site.
5.4 January 31, 2008
After reviewing the laboratory analytical data from the “worst case” impacts remaining at the
former UST location (below four [4] feet), the ODEQ requested that additional soil removal take
place along the northern and southern margins of the former tank concrete mold due to elevated
concentrations of volatile chlorinated solvents (specifically trichloroethene [TCE]), which were
above vapor intrusion screening values. VEC mobilized to the site and removed impacted soils
along the southern side of the concrete mold; the impacted soils were directly loaded into a
truck for disposal at Hillsboro Landfill. The excavation reached a depth of about five (5) feet
bgs, where visibly impacted soils attenuated. ENW collected a total of four (4) confirmation
samples (identified as GS16 through GS19) from the floor and sidewalls of the excavation (see
Figure 4 for locations). After collecting the confirmation samples, the excavation was backfilled
with clean crushed rock.
5.5 February 1, 2008
VEC removed impacted soils along the northern side of the concrete mold; the impacted soils
were directly loaded into trucks for disposal at Hillsboro Landfill. The excavation reached a
depth of about seven (7) feet bgs, when visibly impacted soils attenuated. ENW collected a
total of four (4) confirmation samples (identified as GS20 through GS23) from the floor and
sidewalls of the excavation (see Figure 4 for locations). After collecting the confirmation
samples, the excavation was backfilled with clean crushed rock.
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22. 6.0 ANALYTICAL RESULTS
This section presents the results of the soil and ground-water sampling activities associated
with the UST decommissioning and soil removal activities described in this report.
6.1 Characterization Sampling
As previously stated, initial characterization samples of the UST contents collected in October
and November 2007 indicated that the tank fluids were probably waste oil (based on analysis by
analytical method NWTPH-HCID), and contained low-level concentrations of BTEX,
naphthalene, cis-1,2-dichloroethylene, TCE, and TMBs. The analytical results are presented in
Table 1, following the text. Profiling conducted by Creekside showed the UST contents to be a
hazardous 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 or
RRO). Additionally, several of the VOCs detected in the tank fluid were present in the surface
soils in excess of their most conservative RBC screening values (Table 1). ODEQ determined
that the impacted surface soils, although considered hazardous waste under the “contained-in”
rule, could be disposed at a Subtitle D landfill.3
Based on these results, all subsequent samples (soil and ground water) were analyzed for
DRO, RRO, and VOCs, unless indicated otherwise.
6.2 Residual Subsurface Soil Characterization Sampling
After the tank was removed, ENW collected four (4) soil samples (identified as GS01 through
GS04) from the top of each end of the concrete mold (at four [4] feet bgs). The soils were
visibly impacted with waste oil, and were collected to characterize the magnitude of the impacts
remaining 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 pits
completed at each end of the concrete mold (at nine [9] feet bgs) in order to delineate the
vertical extent of the subsurface soil impacts.
The subsurface soil characterization sampling locations are shown in Figure 3. The analytical
results are presented in Table 1, after the text, and are described here:
Petroleum Hydrocarbons (DRO and RRO): DRO was detected in GS01 through GS04 at
concentrations ranging from 6,000 mg/Kg to 38,000 mg/Kg, exceeding its soil matrix cleanup
level of 500 mg/Kg. RRO was detected at concentrations ranging from 990 mg/Kg to 4,900
mg/Kg, also exceeding the soil matrix cleanup level; however, the results were flagged by the
laboratory as not being indicative of motor oil.
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23. DRO was detected in GS05 (collected from the western test pit) and GS06 (collected from the
eastern test pit) at concentrations of 77 mg/Kg and 170 mg/Kg, respectively, which is below the
soil matrix cleanup level of 500 mg/Kg. RRO was not detected at or above the method reporting
limit in either of these analyzed samples. These results suggest that the vertical extent of
impacted soils at the former UST location is limited to the top of the ground-water table (around
five [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 levels
which did not exceed their most stringent RBC screening values; however, TCE and
naphthalene were detected at elevated concentrations exceeding their most stringent RBC
screening values in samples GS01 and GS02.
PAHs: The sample with the highest DRO concentration (sample GS02) was also analyzed for
PAHs. Several of the PAHs were detected, all but one were below their mostly stringent RBC
cleanup values: benz[a]anthracene was detected at 1.1 mg/Kg, which exceeds its most
stringent RBC value of 0.15 mg/Kg.
6.3 Surface Soil Confirmation Sampling
After 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 the
sidewalls 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 the
method reporting limit in any of the samples analyzed.
VOCs: VOCs were not detected at or above the method reporting limit in any of the samples
analyzed.
Surface soil confirmations sampling results indicate no residual impacts in surface soils
surrounding the former UST.
6.4 Subsurface Soil Confirmation Sampling
After reviewing the laboratory analytical data from the “worst case” impacts remaining at the
former UST location (below four [4] feet), the ODEQ requested that additional soil removal take
place along the northern and southern margins of the former tank’s concrete mold due to
elevated concentrations of volatile chlorinated solvents (specifically TCE), which were above
vapor intrusion screening values. After additional excavation in these areas, ENW collected a
total of seven (7) confirmation samples (identified as GS16 through GS23, GS18 was not
analyzed) from the floor and sidewalls of the excavations. The subsurface soil confirmation
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24. sampling locations are shown in Figure 4. The analytical results are presented in Table 1, after
the text, and are described here:
Petroleum Hydrocarbons (DRO and RRO): DRO and RRO were not detected at or above the
method reporting limit in any of the samples analyzed.
VOCs: VOCs were not detected at or above the method reporting limit in any of the samples
analyzed.
Subsurface soil confirmations sampling results indicate residual impacts were removed from the
areas excavated around the UST concrete mold. However, elevated concentrations of
petroleum hydrocarbons exceeding RBC screening values and Soil Matrix Cleanup Levels
remain in subsurface soils adjacent to the former UST location (Figure 6); therefore, a risk
based assessment was performed and is described in Section 7.0.
6.5 Ground Water Sampling Results
Two (2) ground water samples (USTEX-E and DW-080125) were collected at the former UST
location, one from each of the test pits located on the eastern and western sides of the concrete
mold. Ground water originally entered the test pits at approximately nine (9) feet bgs, but
stabilized overnight at approximately five (5) feet bgs. The ground-water sampling locations are
shown in Figure 5. The analytical results are presented in Table 2, after the text, and are
described 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 of
88 µg/L. RRO was detected at 9,000 µg/L, which also exceeds its screening level RBC of 290
µg/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 BTEX
constituents, butylbenzene, cis-1,2-dichloroethylene, propylbenzenes, and TMBs) were
detected at low levels which did not exceed their respective most stringent RBC screening
values; however, TCE, naphthalene and 1,2,4-TMB were detected at elevated concentrations
which exceeded their most stringent RBC screening values.
PAHs: Only PW-080125 was analyzed for PAHs. Several PAHs were detected, but none
exceeded 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, and
ODEQ granted closure to ground-water impacts at the site with a restriction on future use. This
indicates that the ground-water impacts from the former UST are 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 tight silts and clays in which the
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25. impacts and upper most ground-water table are found). Based on this information and
discussions with the ODEQ, the ground-water impacts in the immediate vicinity of the former
UST were not formally delineated as ODEQ is not requiring formal delineation based on
previous ground-water investigations conducted at the subject site.
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26. 7.0 RISK-BASED ASSESSMENT
Where impacts to soil and ground water are present, the impacts must be evaluated using a
risk-based approach described in ODEQ’s Risk Based Decision Making for the Remediation of
Petroleum Contaminated Sites (RBDM) guidance document, 2003 revision. Appendix A of
ODEQ’s RBDM guidance document and its supplemental guidance materials provided by the
agency provide pre-calculated risk-based concentrations (RBCs) which were developed as
screening levels for suspect sites, based on Oregon unacceptable additional risk criteria for
cancer occurrence and for non-carcinogenic health impacts. The State of Oregon considers
acceptable additional risk of cancer from contact with carcinogenic constituents at less than one
in one million incidences, or for non-carcinogenic constituents, the constituent threshold
concentration at which health impacts would occur. This section conducts a risk-based
assessment for soil and ground water, based on all available analytical data associated with
residual impacts from the UST, as described in this report.
7.1 Identification of Constituents of Interest
Constituents of interest (COIs) associated with UST release (profiled as waste oil) at the site are
listed 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
PCBs
This Risk Assessment will follow the conservative approach of using the highest detected
concentration of each analyte for each medium.
7.2 Identification of Constituents of Potential Concern
Constituents were initially compared to conservative screening-level RBCs to identify
constituents of potential concern (COPCs) in each medium. The residential screening-level
concentrations of Appendix A of ODEQ’s RBDM guidance document and subsequent updated
guidance materials for both soil and ground water are used since this approach is the most
conservative method in assessing potential risk to human heath. The lowest residential RBC is
used in the screening process regardless of whether a pathway is complete or not.
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27. 7.2.1 Soil
Table 1 summarizes the risk-screening of soil samples collected during the UST remedial
actions. 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 respective
analytical method detection limits; however those detection limits exceed the risk-based
screening concentrations. ODEQ does not require cleanup for petroleum constituents that are
not detected by the department-specified analytical methods if standard method detection limits
are 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 impacts
to soil and ground water by analyses of associated constituents. 5
7.2.2 Ground Water
Table 2 summarizes the risk screening of the two (2) ground-water samples collected from the
test pits adjacent to the former UST location. As described in the Table and in Section 6.0 of
this document, naphthalene, TCE, 1,2,4-TMB, DRO and RRO exceeded the screening level
RBCs and are considered COPCs in ground water.
7.3 Conceptual Site Model
7.3.1 Media of Concern
Soil and ground water are impacted at the former UST location. Surface soils (defined as less
than three [3]-foot depth) were impacted from overspill from the top of the tank; however, the
impacts in the surface soils were effectively remediated by excavation as evidenced by
confirmation sampling (Section 6.3), and do not contain any COPCs. Subsurface soils (defined
as 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 surface
soils do not contain any COPCs, they will not be carried through the remainder of this
assessment.
7.3.2 Land Use and Ground Water Use – Potential Receptors
The site is zoned Light Industrial (LI) by the City of Sherwood, which precludes residential
development in the future. Additionally, the site is listed as a CERCLIS site with the EPA and
an ECSI site with the ODEQ due to extensive heavy metal contamination. ODEQ has restricted
any residential development at the site, and has required a paved cap across the surface of the
site 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 and
excavation workers may be exposed to dermal contact with impacted subsurface soils.
5
ODEQ. 2003. RBDM guidance document, Section 3.1.6.3. September.
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28. Additionally, although the entire site will reportedly be paved, this assessment will
conservatively consider possible exposure of occupational workers to surface soils, since
exterior conditions may change in the future. Therefore, the potential receptors include
occupational workers, construction workers, and excavation workers. It is assumed that these
receptors 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 the
vicinity of the subject property. Additionally, ODEQ has determined that there is no beneficial
use of shallow ground water in the vicinity of the site and a ground-water use restriction will be
placed on the subject site. The City of Sherwood supplies water to residents who live within the
City limits. Therefore, the ground-water pathway will not be included in this risk assessment.
7.3.3 Pathways of Concern
An 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 by
which a constituent will be released, retained, or travel in a given medium (e.g., air or ground
water); (3) a point of potential contact with a receptor; and (4) the means by which contact will
occur (e.g., inhalation, ingestion). If any of these elements are missing, the pathway is
considered incomplete. Table 7-1 presents a summary of the pathway analysis for human
receptors.
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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 water
7.3.4 Developed Conceptual Site Model
Based on the above discussion, a conceptual site model has been developed for the former
UST location (Figure 7).
7.3.5 Evaluation of COPCs
Since COPCs were identified by the initial screening, they are further screened by identified
complete exposure pathways.
7.3.5.1 Subsurface Soil
Table 7-2, below, further evaluates the COPCs based on the identified complete exposure
pathways 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 risk
by the identified complete exposure pathways, and are not constituents of concern at in soils
surrounding the former UST.
As mentioned above, ODEQ does not provide a RBC for RRO and regulates RRO impacts by
analyses of associated constituents. As such, all associated constituents have been
appropriately evaluated in this risk assessment and do not present an unacceptable health risk
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30. by the identified complete exposure pathways; therefore, RRO itself does not present an
unacceptable 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 Occupational
Direct or Indirect Pathway (see notes) DC DC DC IV IV
Contaminant 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 - N
Notes:
— = not applicable.
mg/Kg = milligram per kilogram.
c = carcinogenic
nc = noncarcinogenic
v = volatile
nv = nonvolatile
DRO = diesel-range organics.
RRO = residual-range organics.
Bolded concentrations exceed lowest Pathway Specific Risk-Based
7.3.5.2 Ground Water
Table 7-3, below, further evaluates the COPCs based on the identified complete exposure
pathways 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 by
the identified complete exposure pathways, and are not constituents of concern in ground water
in 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 Worker
Direct or Indirect Pathway (see notes) IV IV DS
Contaminant 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 Liter
c = carcinogenic
nc = noncarcinogenic
v = volatile
nv = nonvolatile
DRO = diesel-range organics.
RRO = residual-range organics.
7.4 Evaluation of Risk to the Environment
No sensitive environmental lands were identified at the subject property. However, Rock Creek
and an associated wetlands area are present immediately to the northeast of the site. As
mentioned earlier, ground-water monitoring has been taking place at the site since the 1980’s
and ODEQ agreed that ground water was not a media of concern assuming formal restrictions
EVREN Northwest, Inc. 26 351-05009-06, Rev. 1, 3/17/08

31. of future ground-water use. This indicates that the ground water impacts from the former UST
are 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 tight
silts and clays in which the impacts and upper most ground-water table are found). Based on
this information and discussion with ODEQ, the ground-water impacts in the immediate vicinity
of the former UST were not formally delineated as ODEQ is not requiring formal delineation
based on previous ground-water investigations conducted at the subject site.
Since the former tank location will be capped as part of the proposed development, residual
petroleum-impacted soil (the extent of which is shown in Figure 6) should not present an
unacceptable risk to the environment.
7.5 Discussion
Based 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 at
the former UST location do not present an unacceptable health risk by the identified complete
exposure pathways.
EVREN Northwest, Inc. 27 351-05009-06, Rev. 1, 3/17/08

32. 8.0 CONCLUSIONS AND RECOMMENDATIONS
An approximate 8,000-gallon capacity UST was discovered in October 2007 during demolition
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 most likely used as a
waste 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 the
tank contents exposed debris within the tank; possibly introduced during demolition activities
occurring around the tank. In January 2008, impacted soil around the tank was removed and
disposed at Hillsboro Landfill. At the same time, access to the tank interior was created and
fluids were removed, as were solid debris and sludge. The tank was subsequently cleaned and
transported off-site for recycling. Exposure, cleaning and removal activities showed the tank to
be corroded and leaking. After removal, soils in the tank excavation were observed to be
impacted with oil.
Soil and ground-water assessment, impacted soil removal and soil confirmation sampling
activities ensued. A risk-based assessment of residual soil and ground water impacts showed
they pose no risk to human health or the environment.
As previously approved by ODEQ, previously stockpiled arsenic-impacted soil was used to
backfill the UST excavation, to within four (4)-feet of the ground surface (approximately 30 cubic
yards). The balance of the stockpile was then transported to Hillsboro Landfill.
ENW recommends that a Soil and Ground Water Management Plan which describes
appropriate handling and disposal procedures be developed in the event that residual impacted
soils and/or ground water are disturbed in the future,. ENW further recommends that ODEQ
grant 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 letter
for ten years after he/she sells or otherwise transfers the property.
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33. 9.0 LIMITATIONS
The scope of this report is limited to observations made during on-site work; interviews with
knowledgeable sources; and review of readily available published and unpublished reports and
literature. As a result, these conclusions are based on information supplied by others as well as
interpretations by qualified parties.
The focus of the site closure does not extend to the presence of the following conditions unless
they were the express concerns of contacted personnel, report and literature authors or the
work 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 hazardous
substances that may be present at a given site. ENW’s investigation has been focused only on
the potential for contamination that was specifically identified in the SOW. Therefore, if
contamination other than that specifically mentioned is present and not identified as part of a
limited SOW, ENW’s environmental investigation shall not be construed as a guaranteed
absence of such materials. ENW has endeavored to collect representative analytical samples
for the locations and depths indicated in this report. However, no sampling program can
thoroughly identify all variations in contaminant distribution.
We have performed our services for this project in accordance with our agreement and
understanding with the client. This document and the information contained herein have been
prepared 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 identify
regulation violations related to the presence of hazardous substances other than those
specifically mentioned at the closure site. ENW assumes no responsibility for conditions that
we did not specifically evaluate or conditions that were not generally recognized as
environmentally unacceptable at the time this report was prepared.
EVREN Northwest, Inc. 29 351-05009-06, Rev. 1, 3/17/08