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FOCUSED FEASIBILITY STUDY
+� TIGARD LIBRARY
13500 SOUTHWEST HALL BOULEVARD
TIGARD, OREGON
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MARCH 23, 2009
FOR
CITY OF TIGARD
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GEOENGINEERS
File No.4025-003-02
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Focused Feasibility Study
Tigard Library
File No. 4025-003-02
M March 23, 2009
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Prepared for:
City of Tigard
13125 Southwest Hall Boulevard
Tigard, Oregon 97223
Attention: Dennis Koellermeier
Prepared by:
GeoEngineers, Inc.
15055 Southwest Sequoia Parkway, Suite 140
Portland, Oregon 97224
(503) 624-9274
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Joy RF
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CHRIS K BREEMER
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Chris W. Breemer, R.G. Q�cOLOG`��
Senior Pr ' t Manag
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Am John H. Biggane /
Principal
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P:\4\4025003\02\Finals\402500302FFS.doc
Disclaimer: Any electronic form, facsimile or hard copy of the original document (email, text, table, and/or figure), if provided, and any
attachments are only a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official
document of record.
Copyright®2009 by GeoEngineers,Inc. All rights reserved.
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File No.4025-003-02
TABLE OF CONTENTS '
Page No.
1.0 INTRODUCTION....................................................................................................................................1
2.0 SITE DESCRIPTION AND BACKGROUND..........................................................................................1
2.1 PHYSICAL SETTING...................................................................................................................1
2.2 SITE SETTING.............................................................................................................................1
2.3 GEOLOGY AND HYDROGEOLOGY...........................................................................................2
2.4 PREVIOUS INVESTIGATIONS....................................................................................................2
2.4.1 2002 Phase II Environmental Site Assessment...............................................................2
2.4.2 2003 Assessments and 2004 Soil Removal....................................................................2
2.4.3 Hahn Associates 2005 Assessment and Remediation....................................................3
2.4.4 GeoEngineers 2007 Assessment....................................................................................3
2.4.5 GeoEngineers 2008 Soil and Surface Water Investigation .............................................3
2.4.6 GeoEngineers 2008 Human Health Risk Assessment and Level I and Level II
Ecological Risk Assessment............................................................................................4
3.0 REMEDIAL ACTION OBJECTIVES AND AREAS.................................................................................5
3.1 CONTAMINANTS OF POTENTIAL CONCERN AND AFFECTED MEDIA.................................5
3.2 POTENTIALLY COMPLETE EXPOSURE PATHWAYS..............................................................5
3.3 ARSENIC RISKS TO HUMANS AND ECOLOGICAL RECEPTORS..........................................5
3.4 REMEDIAL ACTION AREAS .......................................................................................................5
3.5 REMEDIAL ACTION OBJECTIVES.............................................................................................6
4.0 HOT SPOT ANALYSIS ..........................................................................................................................6
4.1 HIGHLY CONCENTRATED HOT SPOT CRITERIA....................................................................6
4.2 HIGHLY MOBILE HOT SPOT CRITERIA....................................................................................6
4.3 NOT RELIABLY CONTAINABLE HOT SPOT CRITERIA............................................................6
4.4 HOT SPOT EVALUATION CONCLUSION..................................................................................7
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5.0 REMEDIAL ALTERNATIVE ANALYSIS.................................................................................................7
5.2 DEFINITION OF REMEDIAL ALTERNATIVES............................................................................7
5.2.1 Option 1 - No Action.........................................................................................................7 96
5.2.2 Option 2—Fencing and Capping.....................................................................................7
5.2.3 Option 3- Excavation and Disposal of Contaminated Soil..............................................8
5.2.4 Other Alternatives............................................................................................................8 irw
5.3 COMPARATIVE EVALUATION OF RETAINED REMEDIAL ALTERNATIVES ..........................9
5.3.1 Ability to Attain RAO........................................................................................................9
5.3.2 Effectiveness....................................................................................................................9
5.3.3 Long-Term Reliability.......................................................................................................9
5.3.4 Implementability...............................................................................................................9
5.3.5 Implementation Risk......................................................................................................10
5.3.6 Reasonableness of Cost.................................................................................................10
5.4 SELECTION OF PREFERRED ALTERNATIVE........................................................................10
File No.4025-003-01 Page i GEOENGINEERS
March 23,2009
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TABLE OF CONTENTS (CONTINUED)
Page No.
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6.0 IMPLEMENTATION OF ALTERNATIVE 2...........................................................................................10
6.1 PARKING AREA AND PINE TREE AREA.................................................................................10
6.2 WETLAND AREA AND WILD AREA..........................................................................................10
6.3 NORTH FIELD............................................................................................................................10
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6.4 OTHER REMEDIAL ACTIONS ..................................................................................................10
7.0 CONCLUSIONS...................................................................................................................................11
8.0 LIMITATIONS.......................................................................................................................................11
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9.0 BIBLIOGRAPHY...................................................................................................................................11
List of Tables
ai Table 1. Comparative Analyses of Remedial Alternatives
List of Figures
Figure 1. Vicinity Map
Figure 2. Proposed Remedial Action Areas
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APPENDICES
APPENDIX A—REPORT LIMITATIONS AND GUIDELINES FOR USE ......................................A-1 ... A-3
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File No.4025-003-02 Page ii GEOENGINEERS.0
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FOCUSED FEASIBILITY STUDY
TIGARD LIBRARY
13500 SOUTHWEST HALL BOULEVARD
TIGARD, OREGON
FOR
CITY OF TIGARD
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1.0 INTRODUCTION
This report presents a Focused Feasibility Study (FFS) for the Tigard Library facility located at 13500
Southwest Hall Boulevard in Tigard, Oregon (site). Soil at the site is contaminated with arsenic, most of
which apparently migrated to the site by overland flow from orchards that were historically present west
of the site. This FFS has been prepared for the City of Tigard (City) to identify and evaluate remedial
action alternatives and select a remedial action for the site.
An FFS must include an evaluation of a range of remedial action alternatives in accordance with Oregon's
environmental cleanup requirements(ORS 465.200 et. seq. and OAR 340-122-0010 et seq.) . Typically,
evaluated alternatives include a no action alternative, which evaluates baseline conditions; an alternative
utilizing engineering and institutional controls; a treatment-based alternative; an alternative utilizing ob
excavation and off-site disposal; and an alternative(s) utilizing any combination of the preceding
elements.
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GeoEngineers prepared this FFS on behalf of the City in accordance with our proposal dated January 7,
2007 and City Purchase Order Number 7-1165.
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2.0 SITE DESCRIPTION AND BACKGROUND
Background information for the site, including site location, site description,history, and geologic setting
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is summarized in the following sections:
2.1 PHYSICAL SETTING of
The site is located east of the intersection of Southwest Hall Boulevard and Southwest Wall Street in
Washington County in Tigard, Oregon. Fanno Creek borders the north and east sides of the site. The
approximate 14.7-acre site is located in Township 2 South, Range 1 West, in the northeast quarter of the
southeast quarter of Section 2,of the Willamette Meridian, as shown in Figure 1.
The site is defined as the property occupied by the library facility (Washington County tax lots
2S102DA00600, 2S102DD00100, and 2S102DD00200), public rights-of-way (ROW) adjacent to the
south (Wall Street) and west (Hall Boulevard) sides of the library property, and stream/wetland areas at
the south and southeast of these areas. The site does not include Fanno Creek or areas north or east of
Fanno Creek.
2.2 SITE SETTING to
The site is currently occupied by a library and associated parking and vegetated areas. A pedestrian trail
traverses the east and north sides of the site. The elevation of most of the site is approximately 150 feet 06
above mean sea level (MSL). The site is relatively flat, with the exception of a low area, occupied by
Pinebrook Stream that traverses the south side of the site in a west-east direction. A gentle swale,
ift
File No.4025-003-02 Page 1 GEOENGINEERS
March 23,2009
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oriented in a southwest-northeast direction, runs through the middle of the site. Much of the southwest-
northeast trending swale was filled during construction of the library, and the swale no longer channels
storm water at the site.
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Pinebrook Stream flows across the south side of the site, after entering the site through a culvert
underneath Hall Boulevard. Pinebrook Stream discharges to Fanno Creek near the southeast corner of the
+� site. A storm water pond (the "pond") is located at the southeast corner of the site, adjacent to and north
of Pinebrook Stream. The pond receives stormwater runoff from parking areas at the site. The stormwater
enters the north side of the pond through a constructed channel. During high water events, the pond,
rr Fanno Creek,and Pinebrook Stream are sometimes connected. Site features are shown in Figure 2.
Fanno Creek is a perennial stream with heavily vegetated banks that are approximately 5 feet high.
Fanno Creek discharges to the Tualatin River approximately 2 miles south of the site. The location of
Fanno Creek is shown in Figure 1.
The site is bordered by residences to the west and south and vacant land to the north and east. Southwest
Hall Boulevard borders the west side of the site.
r 2.3 GEOLOGY AND HYDROGEOLOGY
The surface of the site outside of the building footprint is generally covered with trees, shrubs, grasses,
and in some areas, asphalt and concrete. Organic sandy silt with some clay is present in the upper 2 to 5
feet of soil (Shannon and Wilson, 2003). Silt with varying amounts of clay and sand, but fewer organics
is present below the upper organic layer and extends to at least 10 feet below ground surface (bgs), the
maximum depth explored at the site.
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Groundwater has been encountered at depths ranging between 2 and 9 feet bgs. Shallow groundwater
presumably flows toward Fanno Creek.
2.4 PREVIOUS INVESTIGATIONS
Several phases of soil assessment and remediation have been completed at the site between 2002 and the
present. Past investigation activities are described in the following sections. Soil sample locations from
previous and current site investigation activities are shown in Figure 2. Past investigation activities are
r summarized in detail in GeoEngineers' Human Health Risk Assessment and Level I and Level II
Ecological Risk Assessment,dated July 11,2008(hereafter referred to as the"Risk Assessment Report").
2.4.1 2002 Phase 11 Environmental Site Assessment
Hahn Associates, Inc. (HAI) conducted a Phase II Environmental Site Assessment (ESA) at the site in
2002 to evaluate potential impacts to the site from agricultural chemicals. Hahn submitted soil samples
" collected at the site for laboratory analysis of arsenic, copper, lead, and mercury by U.S. Environmental
Protection Agency (EPA) 6000/7000 Series methods; organochlorine pesticides by EPA Method 8081A,
and chlorinated herbicides by EPA Method 8151. Pesticides and herbicides were not detected. Only
arsenic was detected at concentrations exceeding natural background concentrations.
2.4.2 2003 Assessments and 2004 Soil Removal
Apex Environmental Consulting Services, Inc. (Apex) completed two phases of soil assessment in 2002
and 2003 and managed the removal of approximately 3,682 tons of contaminated soil from the site in
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2004. Apex submitted approximately 38 soil samples, collected between the ground surface and
approximately 3.3 feet bgs, for analysis of arsenic. The assessment and remediation conducted by Apex
was primarily completed under the footprint of the library,the pre-2007 parking area and the driveway.
2.4.3 Hahn Associates 2005 Assessment and Remediation
HAI conducted additional assessment in 2005. HAI submitted approximately 55 soil samples, collected
between the ground surface and approximately 6 feet bgs, for analysis of arsenic. HAI also managed the
removal of 155 tons of contaminated soil from areas in the footprint of the pedestrian path that traverses
the east side of the site. HAI summarized the results of their investigation and remediation, as well as
previously completed work in their October 6, 2006, Draft Supplemental Site Investigation Report.
HAI's assessment was predominantly conducted in undeveloped areas to the north, east, and south of the
library and the pre-2007 parking area.
2.4.4 GeoEngineers 2007 Assessment
GeoEngineers collected soil samples during April and June 2007 from the south portion of the site in
areas where the Pinebrook Stream channel was scheduled for restoration. GeoEngineers reported the
April and June 2007 sampling activities in a memorandum dated July 12, 2007.
GeoEngineers collected soil samples from eight locations near the south side of the site during April
2007. Arsenic was detected in eight soil samples collected from five borings, at concentrations between
7.22 and 20.4 milligrams per kilogram (mg/kg). The highest concentrations of arsenic were detected in r
soil collected from boring HA-1 at the southwest side of the site. Leachable arsenic was not detected in a
composite sample.
GeoEngineers collected subsurface soil samples from eight test pits (SP-1 through SP-8) in the planned
stream/wetland restoration area on June 21, 2007. Arsenic was detected in samples collected from eight
test pits at concentrations ranging between 7.96 and 21.1 mg/kg. ,
2.4.5 GeoEngineers 2008 Soil and Surface Water Investigation
GeoEngineers further evaluated soil/sediment and surface water quality in areas affected by the 2007
construction activities and in the pond between February 2008 and May 2008. The 2008 assessment
activities were completed in response to requests from the Oregon Department of Environmental Quality
(DEQ) for additional information about the magnitude and extent of contamination at the site, and in
particular, to evaluate whether the site is contributing arsenic at unacceptable concentrations to Fanno
Creek via discharge of surface water from the pond and via discharge of sediment from Pinebrook
Stream.
The surface water samples were submitted for analysis of turbidity by Standard Method (SM) 213013,
total suspended solids (TSS) by Method 160.2 and total arsenic by EPA Method 6020. The turbidity of
the surface water samples ranged between 15 and 52 nephelometric turbidity units (NTU) and the TSS
ranged between 8 and 73 milligrams per liter (mg/1). The total concentration of arsenic in the surface
water samples ranged between 1.12 and 1.21 micrograms per liter (µg/1). A comparison of the detected
concentrations of total arsenic to turbidity and TSS indicates that the total concentration of arsenic in
surface water samples is relatively unaffected by the suspended load of the samples.
GeoEngineers collected 21 soil/sediment samples and two 3-point composite soil samples in May 2008.
Arsenic was detected in those samples at concentrations as great as 32 mg/kg.
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March 23,2009
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2.4.6 GeoEngineers 2008 Human Health Risk Assessment and Level I and Level 11 Ecological
Risk Assessment
GeoEngineers completed the Risk Assessment Report for the site in July 2008. The Risk Assessment
Report presented a conceptual site model (CSM) and a risk-based screening for ecological and human
receptors. The following contaminant exposure pathways and potential receptors at the site were
identified in the CSM:
• Librarian, maintenance worker, adult and child library/park user, and excavation worker exposure
through soil ingestion,dermal contact with soil and inhalation of soil particulates.
• Ecological receptors in undeveloped portions of the site, including the riparian buffer to Fanno
Creek,grass covered areas,on-site wetland, and Pinebrook Stream.
2.4.6.1 Risk-Based Concentrations for Protection of Human Health
GeoEngineers calculated risk-based concentrations considered protective of human health in the Risk
Assessment Report. The calculated risk-based concentrations are summarized below:
• The arsenic risk-based concentration(RBC) for the Librarian is 8.3 mg/kg.
• The arsenic RBC for the Maintenance Worker is 11 mg/kg.
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• The arsenic RBC for the Adult and Child Park Users is 2.6 mg/kg. DEQ's default background
concentration for arsenic in soil is 7 mg/kg.
r' • The arsenic RBC for the Excavation Worker is 370 mg/kg.
2.4.6.2 Screening Concentrations for Protection of Ecological Health
r GeoEngineers completed the Level I/II Environmental Risk Assessment(ERA)to assess evaluate whether
concentrations of arsenic in soil, sediment, and surface water in the Location of the Facility (LOF) may
pose a potential risk to ecological receptors.
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Sensitive habitat (wetlands and riparian buffer) and potentially complete receptor-contaminant exposure
pathways were identified within the LOF during the Level I ERA. Ecological receptors that may utilize
habitat within the LOF and become exposed to arsenic in soil/sediment include both terrestrial species
(plants, mammals, birds and other terrestrial organisms) and aquatic species (fish, plants, and aquatic
invertebrates within the Pinebrook Stream channel and the pond).
Information developed during the Level II ERA indicates that arsenic in soil does not pose a significant
risk to terrestrial ecological receptors, with the exception of non-T&E plants. Arsenic may be a
contaminant of potential ecological concern (CPEC) for plants because the Exposure Concentration(EC),
based on the maximum detected concentration of arsenic in soil (113 mg/kg), exceeds the DEQ Level II
Screening Level Value (SLV) for non-T&E plants (50 mg/kg). The site-wide average (90 percent upper
confidence level [UCL]) concentration of arsenic (11.9 mg/kg) does not exceed the DEQ Level I1 SLV
for non-T&E plants.
The risks posed by arsenic in sediment were unclear following completion of the Risk Assessment;
irr therefore, GeoEngineers conducted additional investigation in the pond/wetland area in 2008. The
additional investigation is discussed below.
2.4.6.3 Supplemental Sediment Sampling
GeoEngineers conducted additional sediment sampling at the site in 2008 to further assess whether the
arsenic concentrations in sediment could pose an unacceptable risk to aquatic receptors. GeoEngineers
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reported the supplemental sediment sampling results in a letter to DEQ dated January 12, 2009. iii
GeoEngineers collected three 30-point composite sediment samples from the pond/wetland area and
submitted the samples for analysis of arsenic using multi-increment analytical methods (Alaska
Department of Environmental Conservation, 2007). The concentrations of arsenic detected in the Id
composite samples ranged between 10.5 and 12.9 mg/kg, well below the Probable Effect Concentration
(33 mg/kg), indicating that the concentrations of arsenic in sediment at the site do not pose an
unacceptable risk to the health of aquatic ecological receptors. y
3.0 REMEDIAL ACTION OBJECTIVES AND AREAS
The following sections present a description of remedial action objectives (RAOs), and remedial action
areas(RAAs).
3.1 CONTAMINANTS OF POTENTIAL CONCERN AND AFFECTED MEDIA
The only COPC at the site is arsenic.
3.2 POTENTIALLY COMPLETE EXPOSURE PATHWAYS
The following types of people could be exposed to arsenic in soil at the site: librarian or other tit
administrative staff, maintenance workers, adult and child library/park users, and construction/excavation
workers. People could be exposed to arsenic via soil ingestion, dermal contact with soil, and inhalation of
soil particulates.
Terrestrial and aquatic ecological receptors could be exposed to arsenic in soil and sediment.
3.3 ARSENIC RISKS TO HUMANS AND ECOLOGICAL RECEPTORS
The maximum detected concentration of arsenic in soil at some areas of the site exceed relevant risk
screening criteria for human health, indicating that the arsenic concentrations in those area could pose an
unacceptable risk to human health.
The concentrations of arsenic in soil or sediment do not appear to pose an unacceptable risk to terrestrial vii
or ecological receptors.
3.4 REMEDIAL ACTION AREAS 16
RAAs are those portions of the site within which arsenic has been detected at a concentration exceeding
RBCS(Section 2.4.6.1). RAAs at the site include: it
• Area 1 —Pine Tree Area
• Area 2—Parking Lot Area 1A
• Area 3—Wetland Area
• Area 4—Wild Area
• Area 5—North Field
For remedial planning purposes, the wetland area includes a small area at the southeast corner of the
intersection of Wall Street and Hall Boulevard; a single composite sample collected there(sample 005) in
1998 contained 9.07 mg/kg arsenic. It appears that most of the soil represented by sample 005 has been
File No.4025-003-02 Page 5 GEOENGINEERS-0
March 23,2009
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removed during subsequent road and sidewalk construction; however, it is possible that a small amount of
arsenic contamination remains in that area. The RAAs are shown in Figure 2.
.r 3.5 REMEDIAL ACTION OBJECTIVES
The goal of remediation at each RAA is to prevent or minimize human exposure to unacceptable
concentrations of arsenic (7 mg/kg). The remedial action objectives can be achieved through the
reduction of arsenic concentrations in soil or by preventing human exposure to contaminated soil.
4.0 HOT SPOT ANALYSIS
DEQ requires an evaluation for contamination "hot spot" concentrations at the site, as part of a feasibility
study. If a hot spot is identified,DEQ generally requires more aggressive treatment than may be required
for lower contaminant concentrations.
,rr 4.1 HIGHLY CONCENTRATED HOT SPOT CRITERIA
The highly concentrated hot spot level for arsenic is 300 mg/kg(for cancer endpoints)or 4,800 mg/kg(for
non-cancer endpoints)(DEQ, 1999). The highest detected concentration of arsenic in soil at the site(264
mg/kg)is lower than the hot spot concentrations for cancer and non-cancer endpoints.
4.2 HIGHLY MOBILE HOT SPOT CRITERIA
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An area of impacted soil is considered a "highly mobile" hot spot if hazardous substances in soil can
migrate to groundwater or surface water and cause significant adverse effects to the beneficial uses of the
water, and if treatment is reasonably likely to restore or protect such beneficial uses within a reasonable
time. Migration mechanisms may include infiltration and leaching of contaminants in soil to groundwater
or stormwater runoff into surface water.
.r Leaching of arsenic from soil to groundwater is not considered a significant contaminant transport
pathway at the site due to the limited mobility of arsenic in the subsurface. Stormwater discharge from
the pond is not likely to cause significant adverse effects to Fanno Creek because discharge water
contains extremely low arsenic concentrations,based on 2008 stormwater samples.
Arsenic-contaminated sediment migrating in Pinebrook Stream is unlikely to adversely affect Fanno
Creek due to the generally low concentrations of arsenic in the sediment. Three 30-point composite
sediment samples collected from Pinebrook Stream and adjacent wetland areas (seasonally inundated by
Pinebrook Stream) contained concentrations of arsenic that were well below the Probable Effect
Concentration' (33 mg/kg).
4.3 NOT RELIABLY CONTAINABLE HOT SPOT CRITERIA
The extent to which hazardous substances cannot be reliably contained is generally evaluated in the
feasibility study. As discussed in future sections of this report, all the potential remedies considered
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' McDonald, D.D, Ingersoll, C.G, and Berger, T.A., 2000. Development of Consensus-Based Sediment Quality
rr Guidelines for Freshwater Sediment. Archives of Environmental Contamination and Toxicology, 39: 20-
31.
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except the No Action alternative can reliably and effectively contain site contaminants. Therefore, there
are no "not reliably containable"hot spot areas identified.
4.4 HOT SPOT EVALUATION CONCLUSION
No hot spots are present at the site.
5.0 REMEDIAL ALTERNATIVE ANALYSIS
GeoEngineers evaluated remedial alternatives that are likely to be effective for achieving the RAOs and
minimizing risks to human health at the site. The remedial alternatives were selected based on the
applicability of the selected approaches to conditions at the site, discussions with the DEQ, and
demonstrated effectiveness at similar sites.
GeoEngineers developed a conceptual remedial alternative for each considered alternative, along with a
corresponding cost estimate. Each remedial alternative, along with a corresponding cost estimate, is
described below,and a comparison of the alternatives is presented in Table 1. '
The cost estimates presented herein are based on a number of assumptions related to unit costs, inflation,
labor rates, and quantities. The cost estimates are useful for comparing remedial alternatives, but actual 6
costs will vary, depending on the final remedial designs.
5.2 DEFINITION OF REMEDIAL ALTERNATIVES
5.2.1 Option 1 -No Action
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The no action alternative assumes that no remediation activities occur at the site. No action is not an
acceptable remedial alternative because the concentrations of arsenic in soil and sediment at the site
would continue to pose an unacceptable risk to human health.
5.2.2 Option 2—Fencing and Capping
Under this alternative, arsenic risks at the North Field, Wild Area and Wetland Area would be managed
by restricting people's access to those areas. Arsenic risks at the Pine Tree Area and the Parking Area
would be managed by preventing people from directly contacting arsenic-contaminated soil.
5.2.2.1 Access Restrictions
Human access to the North Field, Wild Area, and Wetland Area would be restricted by: 1) installing a
metal chain link and wooden split rail fences, approximately 36 inches tall at the locations shown in a*
Figure 2; and 2)preserving the wild character of areas at the northeast, east, and southeast portions of the
site. The wooden split rail fences would be augmented by: 1) signage, restricting public access to fenced
areas; and 2)thorny plants, such as Oregon grape or wild rose, planted along the base of the fence. The
fence systems would restrict people from entering the RAAs from developed portions of the site, such as
sidewalks and pedestrian pathways, and thereby, limit human exposure to arsenic-contaminated soil.
Wild areas at the northeast, east, and southeast portions of the site and Fanno Creek discourage human
access to the RAAs from undeveloped portions of the site and off-site areas.
5.2.2.2 Capping
Human exposure to arsenic-contaminated soil at the Pine Tree Area and the Parking Area would be
eliminated by capping arsenic-contaminated soil. A number of large trees, which the City would like to
File No.4025-003-02 Page 7 GEoENGINEERS.
March 23,2009 96
preserve, are present at the Pine Tree Area and the Parking Area. Therefore, any cap must be compatible
with the large trees. The proposed cap would consist of a minimum of 6 inches of bark dust or bark
chunks. The cap thickness may be reduced immediately adjacent to large trees, due to the potential harm
caused by overly-thick bark dust adjacent to the trees. The cap would be placed over a demarcation layer
that would serve as a marker between non-contaminated cap material and underlying contaminated soil.
The demarcation layer, consisting of landscape fabric, has already been installed at the portion of the
Parking Area where soil contains concentrations of arsenic exceeding the RAOs.
5.2.2.3 Institutional Controls
+� Access restrictions and capping do not remove the contamination from the site, but they minimize or
eliminate human exposure to contaminated soil, and thereby, reduce or eliminate human health risks.
Because the contamination is not removed from the site, it is necessary to take steps to ensure the long-
term success of these remedies. These steps typically include institutional controls such as deed
restrictions, a maintenance and monitoring plan, and a contaminated media management plan(CMMP).
Under this alternative, deed restrictions would be recorded to notify potential future owners of the
property of the presence of elevated concentrations of arsenic in soil at the site and to record requirements
and limitations associated with use of the property (Le. requirements to maintain fencing and caps and
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restrictions on residential use of the property).
The City would be required to develop and implement a long term maintenance and monitoring plan to
ensure the continued protectiveness of institutional controls. The maintenance and monitoring plan would
require regular(i.e. annual) inspections of fencing and caps and reporting the results of the inspections to
DEQ. If the fencing or cap were determined to be un-protective,the City would be obligated to improve,
repair or replace the damaged fence or cap.
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It would be necessary to develop and implement a CMMP as part of this remedy. The CMMP would
present: 1)the health and safety precautions that the City would implement to protect worker and visitor
++� health; 2) procedures for managing contaminated soil that is disturbed during future maintenance and
construction at the site; and 3)a concise description of the areas that are impacted by contaminants.
5.2.3 Option 3-Excavation and Disposal of Contaminated Soil
Under this alternative, one vertical foot of contaminated soil would be removed from the RAAs. The
contaminated soil would be transported off-site for disposal at an appropriate landfill. The removed soil
would be replaced by 1 foot of clean imported soil and re-vegetated. By removing the upper 1 foot of
contaminated soil, the potential for people to directly contact the impacted soil would be significantly
r reduced. This approach would, however, result in significant damage to habitat at some portions of the
site.
Following successful implementation of this alternative, institutional controls such as deed restrictions
and monitoring and maintenance would not be required. It would be necessary, however, to properly
manage residual contaminated soil, if any, encountered during future grading or excavation activities
occurred at the site within the contaminated soil.
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5.2.4 Other Alternatives
GeoEngineers considered other remedial approaches, such as on-site soil solidification, soil stabilization,
and soil washing, but did not include them in the formal evaluation process because these approaches are
not reasonable for the site due to the limited volume of contaminated material, the size of the site, the
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relatively moderate concentrations of arsenic in soil and sediment at the site and the relatively high cost of r4i
implementing these measures.
5.3 COMPARATIVE EVALUATION OF RETAINED REMEDIAL ALTERNATIVES
GeoEngineers compared the remedial alternatives described in Section 5.2 based on the ability of each
alternative to meet the RAO. The specific criteria that GeoEngineers considered for the comparative
evaluation included: effectiveness, long-term reliability, implementability, implementation risk and
reasonableness of cost.
GeoEngineers developed comparative level cost estimates to evaluate the reasonableness of costs for each
alternative. These cost estimates were based on a conceptual design for each option. While sufficiently
accurate and useful for decision-making purposes, the cost estimates are subject to change based on the
final remedial design. The comparative evaluation of the remedial alternatives is summarized in Table 1.
The following sections present the comparative evaluation.
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5.3.1 Ability to Attain RAO
Alternative 2 (Access Restrictions and Capping) and Alternative 3 (Excavation and Off-Site Disposal)
will achieve the RAO. Alternative 3 would permanently treat most contamination at the site, whereas,
under Alternative 2, contaminated soil would remain at the site, but the risks to human health would be
significantly reduced or eliminated. Alternatives 2 and 3 were ranked equally, based on the likelihood
that they will achieve the RAO. Alternative 1 (No Action) is non-protective and ranked behind
Alternatives 2 and 3. Alternative 1 was removed from further consideration based on the inability to
achieve the RAO. r
5.3.2 Effectiveness
Contamination will remain on site under Alternative 2, and long term operations and maintenance of caps
and fences will be required. If these steps are implemented, Alternative 2 will be effective for achieving
the RAOs.
Alternative 3 offers a permanent remedy for contamination at the site; however, the benefits of the
excavation and off-site disposal may be outweighed by the damage that would be caused to the wetland
area and Fanno Creek. Excavation will disturb large areas of vegetation and soil in wetland and near the ft
creek, leading to significant habitat destruction. In addition,regular flooding near Fanno Creek could lead
to future exposure of un-excavated contaminated soil, if present.Alternatives 2 and 3 were ranked equally
for effectiveness. as
5.3.3 Long-Term Reliability
r
Alternatives 2 and 3 ranked equally for long-term reliability. Alternative 3 does not require long term
maintenance and monitoring; however, it is possible that deeper contaminated soil, if present, in the
wetland area would be remobilized by seasonal flooding. Capping and fencing will provide long-term
protection with proper maintenance.
rA
I*
File No.4025-003-02 page 9 GWENGINEERS
March 23,2009
1
r.
"` 5.3.4 Implementability
Alternative 2 ranked highest for implementability. Alternative 3 ranked below Alternative 2 for
w, Implementability because there is potential for significant permitting challenges associated with
excavation in wetland and flood plain areas at the site.
in 5.3.5 Implementation Risk
Alternative 2 ranked highest for implementation risk because there is very little risk associated with
go installation of fencing and caps. The implementation risks are greater for Alternative 3 because heavy
equipment would be mobilized to the site,posing a potential risk to workers and visitors.
No 5.3.6 Reasonableness of Cost
The estimated cost for Alternative 2 is $65,000 and the estimated cost for Alternative 3 is $520,000.
Estimated costs for each alternative are summarized in Table 2.
rw
5.4 SELECTION OF PREFERRED ALTERNATIVE
M Alternative 2 (capping and access restrictions) is the preferred alternative based on the comparative
evaluation presented above.
+w 6.0 IMPLEMENTATION OF ALTERNATIVE 2
The following sections present the proposed approach for implementation of Alternative 2.
r
6.1 PARKING AREA AND PINE TREE AREA
A 6-inch layer of bark dust or equivalent, underlain by a demarcation layer (geotextile or equivalent),
rr would be applied to the ground surface at the Parking Area and the Pine Tree Area. Some mulch and a
demarcation layer are present at portions of these areas. It may be possible to augment the existing mulch
layer and demarcation layer. The City will be required to conduct routine inspections (anticipated to be
annual)and maintain the cap. Figure 2 shows the location of the proposed capped areas.
6.2 WETLAND AREA AND WILD AREA
Access to the Wetland Area and Wild Area will be controlled by installation of fencing (minimum 36-
inch height) and maintenance of the wild character of the area. Fences will prevent easy access to the
r+■ areas and the wild character of surrounding areas will discourage regular usage of the area by people.
Fencing has been installed along a portion of the wetland area and serves as a suitable access restriction.
New fencing should be installed east of the Parking Area and along a portion of the pedestrian pathway.
..w Figure 2 shows the locations of the current fence and the proposed new fence. The City will be required
to maintain the fence and discourage human use of the Wetland Area and the Wild Area.
6.3 NORTH FIELD
Human access to the North Field will be controlled by installation of fencing (minimum 36-inch height).
New fencing would be installed around the North Field, approximately as shown in Figure 2. The City
will be required to maintain the fence and discourage human use of the North Field.
File No.4025-003-02 Page 10 GEoEN61NEERS
March 23,2009
IN
6.4 OTHER REMEDIAL ACTIONS Ni
Arsenic in sediment in Pinebrook Stream,the pond, and the wetland area has been shown to pose no
unacceptable risk to ecological receptors. Nonetheless,the City should take reasonable steps to minimize it
the potential for erosion from Pinebrook Stream, the pond, and the wetland areas to Fanno Creek. The
City recently installed riprap for erosion protection at the pond outfall. Other erosion prevention steps, if
needed in the future, may include planting and encouraging growth of beneficial vegetation and/or to
installation of additional engineered structures, such as rip rap or woody debris.
7.0 CONCLUSIONS IN
GeoEngineers completed this Focused Feasibility Study to evaluate and recommend remedial alternatives
for addressing potential risks to human health posed by arsenic in soil at the Tigard Library property in
Tigard, Oregon. GeoEngineers considered a number of remedial alternatives and completed a detailed ON
comparison of two alternatives: 1) implementation of access restrictions and capping; and 2) excavation
and off-site disposal of contaminated soil.
me
GeoEngineers recommends that contamination risks be managed using a combination of access
restrictions and capping. The recommended approach offers a long term remedy that will be effective for
managing risks to human health and reasonable in cost. mi
8.0 LIMITATIONS
This Focused Feasibility Study has been prepared for the exclusive use of the City and DEQ for
evaluation of remedial options at the Tigard Library in Tigard, Oregon. This report is not intended for use
by others, and the information contained herein is not applicable to other sites. No other party may rely
on the product of our services unless we agree in advance and in writing to such reliance.
Within the limitations of scope, schedule and budget, our services have been executed in accordance with
generally accepted environmental science practices in this area at the time this report was prepared. No
warranty or other conditions, express or implied, should be understood.
Please refer to the appendix titled"Report Limitations and Guidelines for Use"for additional information am
pertaining to use of this report.
Any electronic form, facsimile or hard copy of the original document(email,text,table, and/or figure), if
provided, and any attachments are only a copy of the original document. The original document is stored
by GeoEngineers,Inc. and will serve as the official document of record.
9.0 BIBLIOGRAPHY
Alaska Department of Environmental Conservation. Guidance on Multi-Increment Soil Sampling, 2007. to
Apex Environmental Consulting Services Inc. Arsenic Contaminated Soils Removal Close Out
Report/Work Plan Update For the New City of Tigard Library Site,2003.
GeoEngineers,Inc. Soil Assessment,Tigard Library,Tigard, Oregon,April 2007.
GeoEngineers, Inc. Human Health Risk Assessment and Level I and Level II Ecological Risk
Assessments, Tigard Library, 13500 SW Hall Boulevard, Tigard, Oregon,2008.
File No.4025-003-02 Page 11 GEOENGINEERS
March 23,2009
r
GeoEngineers, Inc. Letter to Oregon Department of Environemntal Quality regarding Supplemental
Sediment Sampling, Tigard Library, 13500 SW Hall Boulevard,Tigard,Oregon,2009.
Hahn Associates, Inc. Phase II Environmental Site Assessment Report, 14.7 Acre Property, 13360 and
13560 SW Hall Boulevard,Tigard, Oregon,December 2, 2002.
Hahn Associates,Inc.Draft Supplemental Site Investigation Report,October 6, 2006.
McDonald, D.D, Ingersoll, C.G, and Berger, T.A. Development of Consensus-Based Sediment Quality
Guidelines for Freshwater Sediment. Archives of Environmental Contamination and Toxicology,
39: 20-31,2000.
rr Oregon Department of Environmental Quality. Guidance for Identification of Hot Spots, 1998.
Oregon Department of Environmental Quality. Default Background Concentrations for Metals, Memo
from Toxicology Workshop to DEQ cleanup Project Managers, 2002.
err Oregon Department of Environmental Quality. Risk-Based Decision Making for the Remediation of
Petroleum-Contaminated Sites, Including Table of Generic Risk-Based Concentrations for
Petroleum Constituents and Total Petroleum Hydrocarbons and Generic Remedy for Simple
Risk-Based Sites,November, 2008.
RSMeans. Environmental Remediation Cost Data Assemblies,2003.
RSMeans. Environmental Remediation Estimating Methods,2003.
Shannon and Wilson. Geotechnical Investigation, Wall Street LID, Tigard, Oregon, 2003.
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File No.4025-003-02 Page 12 QoENGINEERUO
March 23,2009
TABLE 1
COMPARATIVE ANALYSES OF REMEDIAL ALTERNATIVES
TIGARD LIBRARY
13500 SW HALL BOULEVARD
TIGARD, OREGON
Able to Attain Remedial Effectiveness Long-Term Reliability Implementability Implementation Risk Reasonableness of Cost Overall
Alternative Action Objective RAO Scoring
Comments Score Comments Score Comments Score Comments Score Comments Score Comments Score Score Rank
1) Does not achieve the RAO. 1) Not an effective means of 1)Alternative is not reliable. 1) No action is required for 1)Alternative does not remove
treatment. implementation. risk,therefore it carries high
Option 1 implementation risk.
No Action 0 NIA N/A N/A N/A $0 N/A 0 3
1)Achieves RAO through 1)Adequate technology for 1)Technology widely 1) Equipment for alternative readily 1) Potential for contaminants
removal of exposure pathway. achieving RAO, but deed demonstrated to provide available. to migrate.
Does not remove COCs. restrictions required. reliable outcomes. 2)Construction easily accomplished 2)Minimal worker risk.
Option 2 2)Time frame for achieving 2)Minimal uncertainty with using common techniques.
Capping and 1 5 RAO:6 months. 1 5 long-term reliability. 1 5 3)Moderate disruption of commercial 2 2 $65,000 1 9.5 1
Institutional operations.
Controls 4) Effectiveness easily monitored.
5)Time frame for construction is less
than other options.
1)Achieves RAO through the 1)Adequate technology for 1)Technology widely 1) Equipment for alternative readily 1) Potential for contaminants
removal of soil in the direct achieving RAO, but some demonstrated to provide available. to migrate.
contact and ingestion pathway contamination left on site. reliable outcomes. 2)Construction moderately 2) Presence of earth-work
Option 3 (0 to 3 feet). Does not remove RCRA waiver may be required. 2)Minimal uncertainty with accomplished using common equipment represents minor
Excavation to 3- COC below 3 feet. 1.5 2)Time frame for achieving 1.5 long-term reliability. 1.5 techniques. 1 community risk. 1 $520,000 0 6.5 2
feet RAO:6 months. 3)Moderate disruption of commercial 3)Moderate worker risk.
operations. 4. Presence of earthwork
4) Effectiveness easily monitored. equipment represents a
5)Time frame for construction is moderate risk to Fanno Creek.
Notes:
RAO=Remedial Action Objective
COCs= Contaminants of Concern
-Does not take into account hot spot analysis.See text for discussion
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File No.4025-003-02 G EoENG I N EE R
Table 1,March 23,2009
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8
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9 +� HA-1-HA-30+ Hand—auger sample locations
COMP-1(DA.S)
(April 2007 and May 2008)
Wetland
SP-1 o Soil sample locations (June 2007)
Area
oq)e Pre-2006 Soil samples
X Existing Fence
—X— Proposed Fence—Chain Link
I + --D_� Proposed Fence—Split Rail
x I utfall
Remedial Action Area
$ s
I � / Proposed Cap
Proposed Remedial Action Areas
Tigard Library
Hot": Tigard, Oregon
1.1Te lecafom of of feeturee liftown are epprozYlMte.
2.Thi.d."V to ler Infamlatbn purposes.It is intended to assist In showkV features discussed
In an attached document.GwEnglmen.Inc.tan not guereMee Me acourecy and content of electronic Bee.
The ma,�BasoCo d byGeoE glaxre.Irc.andw*eanaa,theeB mordgf�i.�mmunm,on. G EO E NG I N E E RS�
3.RBC=Ri.k Baso CAncentretlon Figure 2
4.BLV=Oregon DepwlrmM of Emir—wor dal quality Level II ScreeMtg Level Value.
Referenm:Base Drewlrg doled 10/2003,provided by Hahn and Associelee.
..Now �..�
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I Legend:
HA-1 - HA-30 * Hand—auger sample locations
(April 2007 and May 2008)
Outfall SP-1 0 Soil sample locations (June 2007)
ot?e Pre-2006 Soil samples
S
Locality of Facility 1
�� Approximate Area of Soil Exceeding
Adult and Child Park User RBC (2.6 mg/kg)
and Background (7 mg/kg) Areas Exceeding Screening Criteria
El Paved Cap
Approximate Area of Soil Exceeding Tigard Library
Freshwater Sediment (6 mg/kg) and Tigard, Oregon
Notes:
1.The locations of all features shown are approximate. Sediment Bioaccumulation (7 mg/kg) SLVs
2.TMs dIattach d for Information Ge purposes.H is Intended to assist in showing features contediscussed
an attached document.GeoEngineers.Inc.can not guarantee the accuracy and content of electronic files.
The masts,file is stored by GeoEnginaers,Inc.and will some as the official record of this communication. G EO E N G'N E E RS Figure
3.RBC=Risk Base Concentraton
4.SLV=Oregon Department of Environmental quality Level II Screening Level Value.
Reference:Base Drawing dated 1012006,provided by Hahn and Associates.
GWENGINEERS
APPENDIX
REPORT LIMITATIONS AND GUIDELINES FOR USE
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APPENDIX A
REPORT LIMITATIONS AND GUIDELINES FOR USE
This Appendix provides information to help you manage your risks with respect to the use of this report.
ENVIRONMENTAL SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES, PERSONS AND
PROJECTS
This report has been prepared for the exclusive use of the City of Tigard and the DEQ. This report is not
r.r intended for use by others,and the information contained herein is not applicable to other sites.
GeoEngineers structures our services to meet the specific needs of our clients. For example, an
environmental site assessment study conducted for a property owner may not fulfill the needs of a
prospective purchaser of the same property. Because each environmental study is unique, each
environmental report is unique, prepared solely for the specific client and project site. No one except the
City of Tigard and the DEQ should rely on this environmental report without first conferring with
GeoEngineers. This report should not be applied for any purpose or project except the one originally
contemplated.
THIS ENVIRONMENTAL REPORT IS BASED ON A UNIQUE SET OF PROJECT-SPECIFIC FACTORS
This report has been prepared for the Tigard Library in Tigard, Oregon. GeoEngineers considered a
number of unique, project-specific factors when establishing the scope of services for this project and
report. Unless GeoEngineers specifically indicates otherwise, do not rely on this report if it was:
• Not prepared for you.
• Not prepared for your project.
rn • Not prepared for the specific site explored.
• Completed before important project changes were made.
If important changes are made after the date of this report, GeoEngineers should be given the opportunity
to review our interpretations and recommendations and provide written modifications or confirmation, as
appropriate.
RELIANCE CONDITIONS FOR THIRD PARTIES
Our report was prepared for the exclusive use of the City of Tigard and the DEQ. No other party may
++. rely on the product of our services unless we agree in advance to such reliance in writing. This is to
provide our firm with reasonable protection against open-ended liability claims by third parties with
whom there would otherwise be no contractual limits to their actions. Within the limitations of scope,
„r schedule and budget, our services have been executed in accordance with our Agreement with the City of
Tigard and generally accepted environmental practices in this area at the time this report was prepared.
.. ENVIRONMENTAL REGULATIONS ARE ALWAYS EVOLVING
Some substances may be present in the site vicinity in quantities or under conditions that may have led, or
may lead, to contamination of the subject site, but are not included in current local, state or federal
regulatory definitions of hazardous substances or do not otherwise present current potential liability.
GeoEngineers cannot be responsible if the standards for appropriate inquiry, or regulatory definitions of
hazardous substance,change or if more stringent environmental standards are developed in the future.
File No.4025-003-02 Page A-1 GEOEmGmPERS-0
wr March 23,2009
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UNCERTAINTY MAY REMAIN EVEN AFTER THIS FOCUSED FEASIBILITY STUDY IS COMPLETED
No site investigation can wholly eliminate uncertainty regarding the potential for contamination in
connection with a property. Our interpretation of subsurface conditions in this study is based on field
observations and chemical analytical data from widely-spaced sampling locations. It is always possible
that contamination exists in areas that were not explored, sampled or analyzed.
SUBSURFACE CONDITIONS CAN CHANGE
This environmental report is based on conditions that existed at the time the study was performed. The
findings and conclusions of this report may be affected by the passage of time, by manmade events such
as construction on or adjacent to the site, by new releases of hazardous substances, or by natural events
such as floods, earthquakes, slope instability or groundwater fluctuations. Always contact GeoEngineers
before applying this report to determine if it is still applicable.
SOIL AND GROUNDWATER END USE
The cleanup levels referenced in this report are site-and situation-specific. The cleanup levels may not be
applicable for other sites or for other on-site uses of the affected media (soil and/or.groundwater). Note
that hazardous substances may be present in some of the site soil and/or groundwater at detectable
concentrations that are less than the referenced cleanup levels. GeoEngineers should be contacted prior to
the export of soil or groundwater from the subject site or reuse of the affected media on site to evaluate
the potential for associated environmental liabilities. We cannot be responsible for potential
environmental liability arising out of the transfer of soil and/or groundwater from the subject site to
another location or its reuse on site in instances that we were not aware of or could not control.
MOST ENVIRONMENTAL FINDINGS ARE PROFESSIONAL OPINIONS
Our interpretations of subsurface conditions are based on field observations and chemical analytical data
from widely spaced sampling locations at the site. Site exploration identifies subsurface conditions only
at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field
and laboratory data and then applied our professional judgment to render an opinion about subsurface am
conditions throughout the site. Actual subsurface conditions may differ—sometimes significantly—from
those indicated in this report. Our report, conclusions and interpretations should not be construed as a
warranty of the subsurface conditions.
mi
READ THESE PROVISIONS CLOSELY
Some clients, design professionals and contractors may not recognize that the geoscience practices ini
(geotechnical engineering, geology and environmental science) are far less exact than other engineering
and natural science disciplines. This lack of understanding can create unrealistic expectations that could
lead to disappointments,claims and disputes. hili
GeoEngineers includes these explanatory"limitations"provisions in our reports to help reduce such risks.
Please confer with GeoEngineers if you are unclear how these "Report Limitations and Guidelines for
Use"apply to your project or site.
File No.4025-003-02 Page A-2 QoENGINEER�
March 23,2009
GEOTECHNICAL, GEOLOGIC AND GEOENVIRONMENTAL REPORTS SHOULD NOT BE
INTERCHANGED
The equipment, techniques and personnel used to perform an environmental study differ significantly
from those used to perform a geotechnical or geologic study and vice versa. For that reason, a
geotechnical engineering or geologic report does not usually relate any environmental findings,
conclusions or recommendations; e.g., about the likelihood of encountering underground storage tanks or
regulated contaminants. Similarly, environmental reports are not used to address geotechnical or geologic
concerns regarding a specific project.
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BIOLOGICAL POLLUTANTS
GeoEngineers' Scope of Work specifically excludes the investigation, detection,prevention or assessment
of the presence of Biological Pollutants. Accordingly, this report does not include any interpretations,
recommendations, findings, or conclusions regarding the detecting, assessing, preventing or abating of
Biological Pollutants and no conclusions or inferences should be drawn regarding Biological Pollutants,
as they may relate to this project. The term"Biological Pollutants" includes, but is not limited to, molds,
fungi, spores,bacteria, and viruses,and/or any of their byproducts.
�• If the City of Tigard desires these specialized services, they should be obtained from a consultant who
offers services in this specialized field.
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File No.4025-003-02 Page A-3 GEoENGINEEIIS—
March 23,2009