Innovations in Site Characterization
Case Study: The Role of a Conceptual Site Model for
Expedited Site Characterization Using the Triad Approach
at the Poudre River Site, Fort Collins, Colorado
U.S. Environmental Protection Agency
Office of Superfund Remediation and Technology Innovation
Brownfields Technology Support Center
Washington D.C. 20460
Prepared by:
The Brownfields and Land Revitalization Technical Support Center
In cooperation with:
U.S. Environmental Protection Agency Region 8
United States
Environmental Protection
Agency
Office of Solid Waste
and Emergency
Response (5102G)
EPA 542-R-06-007
November 2006
www.epa.gov
clu-in.org
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Notice
This material has been funded wholly by the U.S. Environmental Protection Agency (EPA) under
Contract Number 68-W-02-034. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
Copies of this report are available free of charge from the National Service Center for Environmental
Publications (NSCEP, P.O. Box 42419, Cincinnati, OH 45242-2419; telephone (800) 490-9198 (voice)
or (301) 604-3408 (facsimile). Refer to document EPA 542-R-06-007. This document can also be
obtained electronically through EPA's Clean Up Information (CLU-IN) System on the World Wide Web
at http://cluin.org.
Comments or questions about this report may be directed to Stephen Dyment, EPA, Office of Superfund
Remediation and Technology Innovation (5203P), 1200 Pennsylvania Avenue NW, Washington, B.C.
20460; telephone (703) 603-9903; email: dyment.stephen@epa.gov.
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Foreword
This case study is one in a series designed to provide cost and performance information for innovative
tools that support less costly and more representative site characterization. These case studies include
reports on new technologies as well as novel applications of familiar tools or processes. They are
prepared to offer operational experience and to further disseminate information about ways to improve the
efficiency of data collection at hazardous waste sites.
Acknowledgments
This document was prepared by the U.S. Environmental Protection Agency's (EPA) Office of Superfund
Remediation and Technology Innovation, with support provided under EPA Contract No. 68-W-02-034.
Special acknowledgement is given to EPA Region 8 and to the staff of Tetra Tech EM Inc. for their
thoughtful suggestions and support in preparing this case study.
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TABLE OF CONTENTS
Section
NOTICE i
FOREWORD ii
CASE STUDY ABSTRACT ix
EXECUTIVE SUMMARY 1
1.0 INTRODUCTION 6
2.0 PRELIMINARY CONCEPTUAL SITE MODEL 10
2.1 SITE DESCRIPTION 11
2.2 SUMMARY OF PREVIOUS INVESTIGATIONS 11
2.3 SITE GEOLOGY 14
2.4 SITE HYDROLOGY 14
2.5 MEDIA OF POTENTIAL CONCERN 15
2.6 CONTAMINANTS OF POTENTIAL CONCERN 15
2.7 EXPOSURE ROUTES AND RECEPTORS 16
2.8 PROPERTY REUSE SCENARIO 17
3.0 SYSTEMATIC PLANNING AND PREPARATION IN SUPPORT OF THE TARGETED
BROWNFIELDS ASSESSMENT 17
3.1 INITIAL WORK PLAN 18
3.1.1 Site-Specific Objectives for Initial Work Plan 18
3.1.2 Development of the Original Sampling Approach 18
3.1.3 The New Sampling Approach 19
3.1.4 Analytical Options 20
3.1.5 Developing Decision Logic 21
3.2 GRAB GROUNDWATER SAMPLING DEMONSTRATION OF METHODS
APPLICABILITY 21
3.3 TARGETED BROWNFIELDS ASSESSMENT FIELD EVENT 22
3.3.1 Geophysical Survey 22
3.3.1.1 Geophysical Survey Results 24
3.3.1.2 Geophysical Survey Conclusions 25
3.3.2 Direct-Push Soil/Product Sampling 25
3.3.3 Coal Tar Product Delineation 26
3.3.4 Direct-Push Groundwater Sampling 26
3.3.5 Monitoring Well Sampling Results 27
3.3.5.1 Naphthalene in Groundwater 28
3.3.5.2 MTBE in Groundwater 29
3.3.5.3 Tetrachloroethene in Groundwater 29
3.3.6 Surface Water and Sediment Sampling 29
3.3.7 Product Fingerprinting 30
3.3.7.1 Product Samples Collected from the Poudre River 30
3.3.7.2 Samples Collected from Potential Upgradient Sources 31
3.3.7.3 Correlations of PAHs in River and Upgradient Samples 31
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3.3.7.4 Ratios of PAHs in River and Upgradient Samples 32
3.3.7.5 Summary of PAH Correlation Findings 33
4.0 REVISED PRELIMINARY CONCEPTUAL SITE MODEL 33
5.0 RIVER CHANNEL INVESTIGATION 34
5.1 PROPOSED REVISIONS TO THE CONCEPTUAL SITE MODEL 34
5.2 RIVER CHANNEL INVESTIGATION ACTIVITIES 34
5.2.1 River Channel Investigation Site Preparation 35
5.2.2 River Channel Investigation Drilling Program 35
5.2.3 River Channel Investigation Trenching Program 37
5.3 RIVER CHANNEL INVESTIGATION CONCLUSIONS 37
5.4 EVALUATION OF FUGITIVE EMISSIONS USING GROUND-BASED OPTICAL
REMOTE SENSING TECHNOLOGY 38
6.0 SITE ASSESSMENT ACTIVITIES 39
6.1 SITE ASSESSMENT FIELD SAMPLING ACTIVITIES 40
6.1.1 Soil Gas Survey 40
6.1.2 Passive Diffusion Bag Sample Results 41
6.1.3 Geophysical Survey 43
6.1.4 Soil Sampling 43
6.1.4.1 Soil Core Logging and Soil Sampling Procedures 43
6.1.4.2 Soil Sampling Results 45
6.1.5 Grab Ground-water Sampling 47
6.1.6 Monitoring Well Sampling 47
7.0 CONCLUSIONS 49
7.1 FINAL CONCEPTUAL SITE MODEL 51
7.2 SITE GEOLOGY 52
7.3 SITE HYDROLOGY 53
7.3.1 Surface Water 53
7.3.2 Hydrogeology 54
8.0 LESSONS LEARNED 54
9.0 COST COMPARISON 56
10.0 BIBLIOGRAPHY 59
IV
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TABLES
1 Interested Parties
2 Volatile Organic Compounds Detected in Groundwater during TEA
3 Semivolatile Organic Compounds Detected in Groundwater during TEA
4 PAH Concentrations in ng/kg, Cache La Poudre River Samples and Potential Upgradient Source
Samples
5 TTMW-07 Coal Tar Product Sample Physical Analysis Results from SA
6 Organic Compounds Detected in Soil during SA
7 Soil and Bedrock Geotechnical Analysis Results from SA
8 Organic Compounds Detected in Groundwater during SA
9 Ratio of (B+T)/(E+X) by Sample Location
10 Cost Comparison between a Traditional Approach and the Triad Approach
FIGURES
1 Site Location
2 Site Layout
3 Historical Sample Locations
4 Preliminary Conceptual Site Model
5 Preliminary Bedrock Surface Contour Map with Former River Channel
6 Pathway Receptor Diagram
7 Naphthalene Concentrations in Groundwater - Pre-TBA
8 Sample Decision Logic Diagram
9 TEA - Geophysical Grid Spacing
10 TEA - Geophysical Electromagnetic Survey Results Map
11 TEA - Geophysical Metal Detection Survey Results Map
12 TEA - Naphthalene Concentrations Detected in Groundwater
13 TEA - Tetrachloroethene Concentrations Detected in Groundwater
14 River Channel Investigation Trench and Boring Locations
15 Revised Preliminary Conceptual Site Model
16 SA - Naphthalene Detected in Soil Gas
17 SA - Tetrachloroethene Detected in Soil Gas and Passive Diffusion Bag Sample Locations
18 SA - High Resolution Resistivity Geophysical Survey Transect
19 SA - Geophysical Results
20 SA - Boring and Monitoring Well Locations with Extent of Coal Tar Impacts
21 SA - Final Bedrock Surface Contour Map
22 Final Conceptual Site Model and Cross-Section
23 Investigation History
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APPENDICES
Technology Quick Reference Sheets
Volatile Organic Compounds by Gas Chromatography/Mass Spectrometry (GC/MS)
EMFLUX Passive Soil Gas Sampling System, Analysis by Gas Chromatography/Mass
Spectrometry (GC/MS)
Passive Diffusion Bag Samplers, Analysis by Gas Chromatography/Mass Spectrometry
(GC/MS)
Geonics Limited EMS 1 and EMS 4 Terrain Conductivity Meters
Advanced Geosciences Inc. (AGI) Supersting Resistivity Control Unit (High Resolution
Resistivity Geophysical Survey)
Manufactured Gas Plant Coal Tar Fingerprinting Using Polynuclear Aromatic
Hydrocarbons
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ACRONYMS AND ABBREVIATIONS
1,2,4-TMB 1,2,4-trimethylbenzene
1,3,5-TMB 1,3,5-trimethylbenzene
(ig/kg Microgram per kilogram
(ig/L Microgram per liter
AFCEE Air Force Center for Environmental Excellence
AST Aboveground storage tank
bgs Below ground surface
BTEX Benzene, toluene, ethylbenzene, xylene
BTSC Brownfields Technology Support Center
CDPHE Colorado Department of Public Health and the Environment
cfs Cubic foot per second
COPC Contaminant of potential concern
CSM Conceptual site model
DMA Demonstration of methods applicability
DRO Diesel range organic
EPA U.S. Environmental Protection Agency
FID Flame ionization detector
FSP Field sampling plan
GC/MS Gas chromatography/mass spectrometry
gpm Gallon per minute
GPR Ground-penetrating radar
GRO Gasoline range organic
HRR High-resolution resistivity
HSA Hollow-stem auger
MCL Maximum contaminant level
mg/kg Milligram per kilogram
MGP Manufactured gas plant
mS/m MilliSiemen per meter
MTBE Methyl tert-butyl ether
NAPL Non-aqueous phase liquid
OP-FTIR Open-path Fourier transform infrared
PAH Polynuclear aromatic hydrocarbon
Paragon Paragon Consulting Group, Inc.
PCB Polychlorinated biphenyl
PCE Tetrachloroethene
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PDB Passive diffusion bag
PID Photoionization detector
Poudre Cache La Poudre
ppm Part per million
PRP Potentially responsible party
PVG Poudre Valley Gas
QC Quality control
RETEC RETEC Group, Inc.
SA Site Assessment
START Superfund Technical Assessment and Response Team
Stewart Stewart Environmental Consultants, Inc.
SVOC Semivolatile organic compound
SW-846 Test Methods for the Evaluating Solid Waste
TEA Targeted Brownfields Assessment
TCE Trichloroethene
Tetra Tech Tetra Tech EM Inc.
TPH Total petroleum hydrocarbons
TQRS Technology Quick Reference Sheets
UOS URS Operating Services, Inc.
USGS United States Geological Survey
UST Underground storage tank
UV Ultraviolet
VOC Volatile organic compound
Western Western Environmental Technologies, Inc.
Vlll
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CASE STUDY ABSTRACT
Cache La Poudre River
Fort Collins, Colorado
Site Name and
Location:
Cache La Poudre River
Site
200 Willow Street
Fort Collins, Colorado
80524
Points of Contact:
Karen A. Reed, Project
Manager
reed.karen@epa.gov
Paul Peronard, Project
On-Scene Coordinator
Peronard.Paul@epa.gov
U.S. EPA
999 18th St., Ste. 300
Denver, CO 80202
303-312-6019
Description:
This case study examines how systematic planning, an evolving conceptual site model
(CSM), dynamic work strategies, and real time measurement technologies can be used to
unravel complex contaminant distribution patterns and design a remedy at the Cache La
Poudre (Poudre) River site. The investigation and design of the remedy involved a
former burn landfill, hydrocarbon fuel contamination, and mobile manufactured gas
plant (MGP) coal tar waste. The remedy was driven by recreational reuse and proximity
to the Poudre River. The remedy involved pathway elimination and stream restoration
in a location central to the City of Fort Collins, Colorado. Sites like this one are not
uncommon throughout the United States as urban development reaches out to formerly
rural areas near former MGPs. Thousands of similar sites are found across the United
States, many of which have gone without mitigation because of similar issues in terms of
the complexity and the contaminant distributions and political considerations making
resolution of reuse issues perplexing. In this case study innovative technologies and
strategies are discussed, which can help others with similar sites begin to address
stakeholder concerns in a streamlined and economic fashion.
The site had been studied for several years; however, the specific goals of those studies
resulted in a lack of a full understanding of contaminant distributions and pathways for
migration. Furthermore, contamination did not adhere to typical patterns of migration.
Site-specific conditions limited the extent of dissolved plume contamination in and
around the non-aqueous phase liquid (NAPL) plume, making it difficult to identify and
track contamination from the source area to the Poudre River. Through the cooperative
efforts of the responsible parties, the regulators, and other stakeholders, a systematic
plan involving the use of innovative approaches was used to progressively refine the
CSM, select appropriate technologies, and sequence data collection efforts. The
evolving CSM became the backdrop upon which site decisions were based, directing a
realignment of investigative goals and providing a logical method for dissection of
critical issues related to nature and extent of contamination and design of the remedy.
By relying heavily on an evolving CSM, the project team finished the site
characterization and attribution of responsibilities in less than a year. A remedy
consisting of a barrier wall to stop the flow of coal tar to the river was installed along
with a groundwater extraction system to remove hydraulic head, which has been driving
the transport of coal tar a year after the characterization was completed. Rehabilitation
of the Poudre River channel was also performed to restore the recreational potential and
natural beauty of the area.
The investigatory and remediation efforts have so far included the following mix of
innovative and traditional technologies:
• Electromagnetic induction and resistivity surveys
• Direct-push grab groundwater sampling and real-time analyses for volatile
organic compounds (VOC)
• Passive soil gas survey to identify chlorinated solvents
• Passive diffusion bag sampling of groundwater exiting to surface water
• Auger drilling and trenching accompanied by fixed lab analyses
• Open-path Fourier transform infrared (FTIR) spectroscopy to identify VOC
emissions from the landfill area in three dimensions
• Sheet pile wall with a water extraction and treatment system
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The technologies were employed in concert to develop and refine a CSM and improve
the certainty of decision making. Because of the high profile nature of the site, being
near the city center, results were shared with the press on a regular basis to keep the
public informed of project findings.
Background
The Poudre River site was accepted by the U.S. Environmental Protection Agency
(EPA) for a Targeted Brownfields Assessment (TEA) in May 2003. Contractor support
to EPA Region 8 was provided under the Superfund Technical Assessment and
Response Team 2 contract, initially by URS Operating Services, Inc. and subsequently
by Tetra Tech EM Inc. (Tetra Tech). In October 2003, EPA issued a Technical
Directive Document for Tetra Tech to conduct a site assessment after coal tar was
identified in the Poudre River during the TEA. Historical records also indicated the
presence of low levels of chlorinated solvent and hydrocarbon related constituents in
groundwater beneath the site. The City of Fort Collins, in conjunction with
stakeholders, identified the primary objectives for TEA data collection as establishing a
connection between potential source areas and coal tar contamination found in the river,
and to determine the potential for formal closure of the landfill. As part of this effort,
data were also to be collected to support redevelopment efforts.
The site also contains a former 12-acre landfill that operated from the late 1930s to the
early 1960s. Upgradient of the former landfill on which the current recreation facility
and several other buildings are located is a historical MGP that operated from
approximately 1900 to 1930, manufacturing heating oil from coal and other petroleum
products using a carbureted water gasification method. The major byproduct and
subsequent contaminant from the MGP operation was coal tar. Portions of the former
MGP property were purchased by a gasoline supply company and an energy utility
company. Several releases of gasoline were recorded between the closing of the MGP
and the present. Contaminated groundwater associated with the landfill and coal tar
associated with historical MGP operations were identified below the landfill and in the
nearby Poudre River.
Contemporary features on the 19-acre property include the Northside Aztlan Community
Center, a United Way facility, a park, playground, bike path, and parking areas. The
City of Fort Collins currently operates a recreation center on the former landfill property
and is interested in redevelopment of the site. Public interest and support is high for the
construction of a new 50,000 square foot multi-generation recreation center on the
property. Restoring the site and the nearby Poudre River will provide public access to
river resources and protect recreational users and fisheries as well as wildlife habitat
associated with the Poudre watershed.
Media and
Contaminants:
Groundwater:
• Site groundwater currently contains contaminants associated with coal tar,
nearby gasoline and diesel spills, and possibly landfill materials or other
unknown sources. Contaminants of potential concern primarily include
polynuclear aromatic hydrocarbons (PAH), benzene, toluene, ethylbenzene, and
xylene (BTEX) compounds, total petroleum hydrocarbons (TPH), methyl-t-butyl
ether, trichloroethene, and tetrachloroethene.
Subsurface soil and river sediments
Subsurface soil and river sediments are impacted by NAPL materials containing
PAHs, BTEX compounds, and TPH.
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Results:
Attribution of the responsibility for the cleanup and the design of a remedy were
accomplished in less than 6 months. Numerous innovative technologies (see below)
provided a high density of information to help direct sampling and analysis efforts.
Mitigation efforts were completed a year after characterization was completed by the
primary responsible party to eliminate the continuing source of coal tar to the Poudre
River and restore the river channel to native condition. Sufficient information was
developed to support closure plans for the landfill and to support redevelopment at the
site. The primary lesson learned from this site is that the use of innovative high density
sampling methods in combination with traditional methods and an evolving CSM can
help build understanding and trust (or social capital) amongst stakeholders thus
accelerating the process needed to reach project objectives.
Technologies
Demonstrated:
Innovative or real-time measurements applied at the site included the following methods:
• Direct-push groundwater sampling methods
• Electromagnetic geophysical methods
• High-resolution resistivity geophysical methods
• On-site gas chromatography/mass spectrometry analysis of VOCs in
groundwater
• Passive soil gas
• Passive diffusion bag groundwater sampling methods
• Open-path FTIR spectroscopy
Various vendors were used to provide these services and are described in more detail in
the Technology Quick Reference Sheets provided in this case study (Appendix 1). The
EPA Region 8 mobile laboratory provided equipment needed to generate real-time
results for volatile organics in groundwater using a Modified SW-846 method 8260.
Cost Savings:
Use of the Triad approach for site characterization resulted in an estimated cost savings
of approximately 30 percent when compared with a more traditional approach that
would involve multiple mobilizations and fixed-based analytical methods. In addition to
saving costs, use of the Triad approach increased the size and quality of the data set used
to make decisions about the site. Adequate characterization assured that a functional
mitigation strategy was installed appropriately during the first attempt. It is difficult to
evaluate the cost savings associated with installation of a poorly designed initial remedy,
but the cost of the remedy in this case was approximately $ 13 million, so installation of a
poorly designed system would have been very expensive in the long run.
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CACHE LA POUDRE RIVER SITE
EXECUTIVE SUMMARY
The following case study was prepared by Tetra Tech EM Inc. (Tetra Tech) in support of the U.S.
Environmental Protection Agency's (EPA) Office of Superfund Remediation and Technology Innovation,
Brownfields Technology Support Center (BTSC). The case study was developed as part of EPA's
ongoing Triad initiative to promote streamlining cleanups at hazardous waste sites. The Triad approach
uses a well defined systematic planning process, dynamic work strategies, and real-time measurement
technologies to limit decision uncertainty and maximize the efficiency of activities conducted in support
of cleanup at hazardous waste sites.
The Cache La Poudre (Poudre) River site is located in downtown Fort Collins, Colorado and the owner
of the property is the City of Fort Collins. The area of concern is a commercial area comprising
approximately 19 acres, which includes the Northside Aztlan Recreation Center, the United Way
Building, a park, soccer fields, playground, bike path, river front, and a parking area. The site is adjacent
to a historical manufactured gas plant (MGP) that operated just west of the property from approximately
1900 to 1930, which has since been demolished. The former MGP site is currently owned and operated by
Schrader Oil as a petroleum distribution station. The site is the former location of a city owned and
operated municipal burn landfill, which operated from approximately 1940 to the mid-1960s.
In May 2003, EPA issued a Targeted Brownfields Assessment (TEA) grant to evaluate the potential for
official landfill closure to support the planned expansion of the recreation center, which was built on the
former landfill. Coal tar and sheen, which had been observed in Poudre River sediment was also a
concern relative to recreational use planned along the river front. Contractor support to EPA Region 8
was provided under the Superfund Technical Assessment and Response Team (START) 2 contract,
initially by URS Operating Services, Inc. and subsequently by Tetra Tech. Region 8 Brownfields staff
requested planning/scoping support from the BTSC to apply the Triad approach to the project.
A preliminary conceptual site model (CSM) was developed based on a review of existing data from
previous investigations conducted at the site by Walsh Environmental. The preliminary CSM indicated
that potential threats to human health and the environment could include, but were not limited to
discharge of contaminated groundwater to the Poudre River and direct contact with contaminated surface
water and sediments. Contaminants of potential concern included petroleum-related substances found in
coal tar and suspected to be related to operation of the former MGP. Leaching of contaminants from the
nearby landfill and fuel related storage facilities were also identified as a potential concern.
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A review of the analytical results collected during previous investigations showed that a dissolved plume
of benzene, toluene, ethylbenzene, and xylene (BTEX), polynuclear aromatic hydrocarbons (PAH), as
well as diesel range organics existed in groundwater beneath the portion of the site immediately adjacent
to the former MGP and petroleum storage facility. Methyl tert-butyl ether (MTBE) was identified in
groundwater in a small area on the northwest side of the site. Consultants working for various interested
parties theorized that coal tar found in the river was related to dumping in the landfill, migration of the
coal tar from the MGP to the river, or upgradient source areas. Because of the lack of a dissolved phase
plume that extended from the former MGP across the site to the river, it seemed unlikely that migration
from the former MGP was occurring. The project teams rallied around the refinement of the CSM both
near the river (RETEC Group, Inc. [RETEC] for Xcel Energy) and across the potential flow path from the
former MGP, across the site, to the river. Separate investigations were performed by each party which
culminated in the resolution of the flow path and design of the remedy in an efficient manner.
The initial TEA work plan called for a round of groundwater sampling and collection of water level
measurements to obtain a baseline for the investigations to be conducted. The BTSC developed a
"dynamic" sampling strategy based on the principles of the Triad approach to increase the density of
sampling through the use of an array of innovative and field-based measurement technologies. The TEA
work plan, developed by the Tetra Tech START 2 team as part of the TEA (in cooperation with the
BTSC and EPA Region 8) called for the use of a geomagnetics survey and direct-push groundwater
sampling coupled with on-site analysis of groundwater samples using gas chromatography/ mass
spectrometry for volatile organic compounds (VOCs) to delineate further the dissolved phase plume.
Sampling activities were initiated in June 2003. The geophysical survey employed EM-34 terrain
conductivity meters. This technique was used to define the top of the bedrock surface and identify
metallic objects such as buried drums in the landfill. Direct-push methods were used to collect grab
groundwater, soil, and any product encountered from across the site.
Results from the groundwater grab samples were analyzed on site in near real time using a modified EPA
SW-846 Method 8260 to provide information on contaminants known to be present at the site such as
tetrachloroethene (PCE), naphthalene, and BTEX. These results were used to further refine the CSM and
provide an indication of areas where contamination and coal tar non-aqueous phase liquid (NAPL) might
be present or migrating in the subsurface. Based on the initial geophysical survey results and direct-push
groundwater sampling program, additional small gauge and full-sized monitoring wells were installed.
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The results of the TEA were inconclusive regarding the pathway and source characteristics for coal tar;
however, a plume of PCE was identified. Information obtained during the TEA was used to refine the
CSM and develop strategies for the collection of data during a subsequent site assessment, which was
needed once significant quantities of coal tar were observed in the river.
Concerns had been expressed by the City of Fort Collins about the potential for emissions of landfill
gases and the potential for vertical migration of hazardous VOCs from coal tar associated contaminants,
which could impair the city's plans to redevelop the landfill area. With support from the Monitoring and
Measurement Technologies for the 21st Century initiative, EPA's office of research and development
demonstrated the use of open-path Fourier transform infrared (OP-FTIR) spectroscopy at the site to
evaluate fugitive emissions from the landfill area. The OP-FTIR method facilitates the collection of high
density data and thus provides decision makers with a higher level of confidence that no emission sources
were missed during the investigation. This survey showed that fugitive gas concentrations were
sufficiently high as to warrant the appropriate design considerations during construction and confirmed
the presence of hydrocarbon vapors above select portions of the landfill and free product plume. For
more information concerning the use of OP-FTIR spectroscopy, see:
http://clu-in.org/programs/21.m2/openpath/op-ftir/ .
In October 2003, EPA issued a Technical Directive Document for Tetra Tech to conduct a full site
assessment (SA), primarily to identify the source and pathways for coal tar observed in the Poudre River
during the TEA. A river channel investigation was simultaneously initiated by a potentially responsible
party (PRP) since definitive evidence as to the source of coal tar in the river appeared to be lacking.
Because there was no well defined dissolved phase plume connecting the former MGP area with the
observed seep of coal tar in the river, the PRP suspected that the source might be from areas other than
the former MGP. During the river channel investigation, trenches were dug within the river channel and
along the edges of the river bank where coal tar had been found. Traditional drilling methods were also
used in an attempt to delineate the extent of contamination. Results of this investigation indicated that
coal tar contamination was laterally pervasive along the interface between the shale bedrock and the
overlying alluvium within the river channel and extended to some depth below the bedrock surface. Coal
tar appeared only within the bedrock in upgradient areas outside of the river channel indicating that the
coal tar might be moving within bedrock fractures. These findings reinforced the need for further
investigative activities to identify source areas and define the pathway between the river and source areas.
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A passive soil gas survey was then performed along with a high-resolution resistivity geophysical survey
to further optimize where traditional drilling methods could be used to define the flow path for the
observed contamination. Passive diffusion bag samplers were placed along the edge of the river bank
where groundwater discharged to the river bed to provide information regarding the potential release of
VOCs to the river (for more information see: http ://sc .water.usgs. go v/publications/difsamplers .html).
Results of the soil gas survey indicated the presence of PCE in the landfill. Passive diffusion bag sampler
data also indicated that PCE in groundwater was discharging to the river at very low levels in areas
adjacent to where the soil gas survey indicated the presence of PCE. However, concentrations exiting the
site were relatively low, suggesting either a high dilution rate or that the PCE was primarily trapped in the
vadose zone within the landfill.
Based on the results of the traditional drilling effort in the landfill, which was optimized using trenching
results from the river channel investigation conducted by the primary responsible party, coal tar was
found on and below the bedrock surface across the western half of the site. As it migrated across the site,
coal tar penetrated into the fractured bedrock presumably following fractures until it reached an exit point
to the river.
The primary responsible party, Xcel Energy, implemented a mitigation strategy that included the
placement of a sheet pile wall to intercept coal tar migrating to the river and a French drain to remove the
hydraulic head created by the sheet pile wall. Source remediation is also being considered to further limit
the potential for coal tar migration to the river.
Cost savings for site characterization from the application of the Triad, as compared with the use of a
more traditional, phased approach were estimated at approximately 30 percent. Limited investigations
including Phase I and Phase II investigations and groundwater plume monitoring had been ongoing at the
site for more than 3 years. However, development and refinement of the site CSM revealed that many of
the previous investigations had failed to collect data that met the requirements to make project decisions
regarding a remedy, partially because differing investigation objectives and conventional approaches to
drilling, well installation, and sampling resulted in data gaps. Specifically, the TEA and refinement of the
site CSM identified the need to map the bedrock surface beneath the site and evaluate the presence or
absence of coal tar within the bedrock.
Within 6 months after systematic planning began for the TEA, EPA was able to negotiate with Xcel
Energy, a former owner of the property where the former MGP was located, to conduct a voluntary
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investigation of the extent of coal tar in the Poudre River. The TEA investigation and subsequent
refinements of the CSM allowed EPA to secure additional funding for an SA, which identified source
areas and fully delineated the nature and extent of the contamination on the site as well as facilitated the
implementation of a remedial alternative that was installed by Xcel Energy.
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1.0 INTRODUCTION
This case study was developed as part of U.S. Environmental Protection Agency's (EPA) ongoing
initiative to promote the use of an integrated approach called the Triad. The Triad approach focuses on
sound science using systematic planning, dynamic work strategies, and real-time measurement
technologies to limit decision uncertainty at hazardous waste sites. Historically, sites have been cleaned
up using a relatively static approach ("command and control") to the cleanup process. This type of an
approach afforded both the purchaser and provider of services a certain level of comfort concerning what
activities would be performed and how much they would cost. The command and control type of
approach is not as efficient when attempting to manage a moving target, such as unforeseen
contamination.
Regulators and site managers are increasingly recognizing the value of implementing a more dynamic
approach to site cleanup that is flexible, and recognizes site-specific decisions and data needs that can
increase project efficiency, reduce decision uncertainty, and expedite site reuse. The EPA's Triad
initiative is just this type of dynamic approach. The Triad approach enables project managers to expedite
site cleanup and reduce project costs. As such, the Triad is actually a more powerful tool for cost savings
when used in support of the design, implementation, and optimization of cleanup processes where the
preponderance of costs is generally incurred.
Overview of the Triad Approach
The past decade has seen significant advancements in data collection technologies and measurement
systems. For many contaminants of concern, it is now possible to obtain information about their presence
and level in "real-time", or quickly enough to potentially affect the progress of sampling work.
Advancements in Global Positioning Systems allow rapid determination of spatial locations. Direct-push
technologies provide a quicker and cheaper method for retrieving subsurface samples, and provide the
possibility for pushing sensors into the ground for in situ measurements. In addition, over the last 30
years the professional environmental cleanup community has gained a much belter understanding of
likely contamination scenarios, and the environmental fate and transport processes that determine the
future state of contaminated sites. This knowledge, combined with technology advancements, provides a
new approach to address the uncertainty associated with hazardous waste site decision-making, and the
design and implementation of cleanup strategies.
EPA has coined the term "Triad" to refer to this approach. EPA believes that implementation of the Triad
can potentially lead to faster and more cost effective hazardous waste site remediation, while at the same
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time improving the overall decision-making process and ultimately achieving the final goal of hazardous
waste site programs: safe return of sites for productive use.
Systematic Project Planning
This component of the Triad approach is the farthest-reaching, as it covers the process of a remedial
project from beginning to end. Systematic project planning refers to a systematic process of establishing
a project team composed of all stakeholders, discussing and agreeing upon clear project objectives for site
redevelopment, creating a conceptual site model (CSM) that documents the current understanding of the
site, and managing the project in such a way that data collected during site characterization and
remediation is used to update the CSM as the project proceeds. The goal of systematic project planning is
to create an investigative and remedial approach for the site that reduces decision uncertainty to an
acceptable level. This is accomplished by creating a dynamic work strategy that uses real-time
measurement systems to fill in gaps in understanding of the CSM.
One critical aspect of systematic project planning is building understanding and trust, often referred to in
Triad projects as social capital, amongst the various stakeholders. This sets the stage for understanding
end user data needs and identifying exit strategies.
An important aspect of Triad projects is to plan a demonstration of methods applicability (DMA) for each
real-time measurement system or decision support tool to be used at the site. The DMA can establish the
suitability of a tool for characterizing the site, and can also show that the tool will work effectively in the
environment of the site.
During later stages of a project, the CSM becomes more of a site model with real data making conditions
sufficiently well understood such that a cleanup strategy can be evaluated. Fine-tuning the site conditions
and monitoring of process efficiency become the focus of the data collection efforts performed in support
of process optimization. Stakeholders can remain the same or even change as the focus in a project leans
towards system design optimization, but communication of results, and learning from these results to
optimize the project design, are areas where environmental professionals have experienced the greatest
challenge to existing site assumptions.
System designs create changes in the natural environment, making previous assumptions concerning
design inadequate. The heterogeneity in the environment for certain types of sites, such as those where
dense non-aqueous phase liquid contaminants are involved, may indicate that previous characterization
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efforts prepared in support of design are inadequate to accomplish project goals. For this reason, dynamic
work strategies are needed to continually refine a project team's understanding of site conditions on a
level adequate to support design and system optimization.
Dynamic Work Strategies
In a Triad project, dynamic work strategies are developed based on very specific project decisions.
Project stakeholders weigh in during the development of initial dynamic work strategies, which are
usually designed to support site characterization of potential risks to human health and the environment.
The initial dynamic work strategies developed for a site often take the form of a decision logic diagram
based on the preliminary CSM. The decision logic or strategy is designed to test the assumptions of the
CSM during characterization and ultimately during cleanup. Once characterization of risk has been
estimated and the need for further action identified, the focus of dynamic work strategies for a project
generally shifts towards remedy design objectives and risk management strategies.
Additional data types are rolled into the decision logic, and manageable decision units are introduced
where necessary. As preliminary testing of a design is warranted, empirical data concerning process
efficiencies and inadequacies may also be introduced into the decision logic, and new or better defined
hypotheses may be tested. As implementation goes full scale, characterization efforts in support of
disposal or treatment options may warrant additional revisions to dynamic work strategies and decision
logic. To assure success, the project team may need to introduce data and information of many types that
were not previously obvious to a project team. Data usually need to be collected on a much finer scale
once areas of concern have been identified. Data density is usually driven by the economics of a design
during the final stages of a project, or by the nature of the remedy being considered and or applied.
Real-Time Measurement Systems
The use of real-time measurement systems is very useful for site characterization to assure that
representative results are used to evaluate initial risk at a site, and to develop the preliminary CSM used in
support of risk characterization efforts. The less specific nature of some field-based tests and the
emerging nature of some of the technologies make the direct application of field-based technologies to
risk estimation challenging. Real-time measurement systems can sometimes be used in direct support of
risk or lack of risk determination when a DMA is used to solidify the reliability of the results relative to
project-specific risk related decisions.
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One of the primary advantages of using real-time technologies for guiding and confirming cleanup
objectives is that the lower cost allows for increased data density. This in turn increases decision
certainty. The project team can decide whether to strike a balance between reduced cost and reducing
uncertainty such that both are optimized in comparison to a traditional approach.
As more data are gathered concerning the utility of field-based methods to provide site-specific
information and the need for risk estimation quality data diminishes, field-based technologies have an
increased level of apparent benefit to a project. As unforeseen conditions arise during excavation or
application of a remedy, real-time sensors can and should be used to identify and adapt to the changing
project needs and site conditions. Because of the dynamic nature of natural systems and the changes
induced during remedial efforts, field-based technologies during remedy testing and design optimization
should be an essential element of any post-implementation monitoring and measurement scheme.
The Triad approach, a framework for efficiently managing decision uncertainty, can be applied to a site to
reach project objectives faster and with fewer mobilizations. In addition, it is well suited to Brownfields
projects where budget and schedule are crucial to successful project completion. Further information
about the Triad approach is available on the World Wide Web at http://www.triadcentral.org, and in
"Using the Triad Approach to Streamline Brownfields Site Investigation and Cleanup" (EPA 542-B-03-
002; June 2003).
Background
The Brownfields Technical Support Center (BTSC) project members documented site activities in this
case study, including the planning process and lessons learned by the Poudre River project teams. Such
case studies are being developed by BTSC to assist others during the planning process at similar sites
where Triad concepts are being considered for streamlining the site assessment (SA) and cleanup process.
Thousands of other manufactured gas plant (MGP) sites are present across the United States and case
studies like this one will add to the foundation of knowledge available on potential approaches that might
be advantageous to consider.
The Cache La Poudre (Poudre) River site is located in downtown Fort Collins, Colorado and the current
owner of the property is the City of Fort Collins. The site includes a historical MGP that operated just
west and adjacent to the site from approximately 1900 to 1930, which has since been demolished, and a
former municipal landfill that operated on the city's property from the late 1930s to the mid-1960s.
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Poudre Valley Gas (PVG) Company produced manufactured gas in the first three decades of the twentieth
century, until approximately 1930. The plant manufactured heating oil from coal using a carbureted water
gasification method. Two gasholders (49.5 feet and 52 feet in diameter) were present at the site in the
1930s. One tar pit of unknown size was located north of the smaller, western gas holder. The
aboveground portion of the western gasholder was removed before 1941. The second gasholder is thought
to have been removed in 1966 (Walsh 200la).
In May 2003, EPA issued a Targeted Brownfields Assessment (TEA) grant to evaluate the potential for
official landfill closure. The goal of the evaluation was to facilitate the construction of a new community
recreation center on the city's property and identify the source of coal tar and sheen observed in the
Poudre River. Contractor support to EPA Region 8 was provided under the Superfund Technical
Assessment and Response Team (START) 2 contract, initially by URS Operating Services, Inc. (UOS)
and subsequently by Tetra Tech EM Inc. (Tetra Tech). Region 8 Brownfields staff requested
planning/scoping support from the BTSC to apply the Triad approach to the project. Table 1 provides a
summary of all parties involved.
2.0 PRELIMINARY CONCEPTUAL SITE MODEL
A CSM is an important planning tool used to compile and communicate essential site data needed to
understand and then map out a strategy for site closure and cleanup. Key features of a site relative to the
site-specific environmental decisions are the input to the model. As the model is refined based on those
results needed during design and ultimately remediation of environmental conditions at a site, it becomes
far less conceptual. The project team develops the preliminary CSM based on existing data before an
investigation is planned and implemented. Existing data, such as geologic, hydrogeologic, contaminant
types, source area characteristics, and other pertinent information are carefully reexamined to assure that
the data proposed to be collected will be of sufficient quality and quantity to meet the project objectives.
Project objectives are clearly stated and then translated into site-specific decisions and data collection
activities designed to answer the questions raised by the existing data.
A CSM includes the identification of suspected contaminant sources and types of contaminants present,
potential receptors and exposure points, potential migration pathways, and other project constraints. The
CSM uses existing information on the types of contaminants, pathways, receptors, and future land uses to
help define areas where further study is needed. The CSM is continually refined as information is
gathered. Modifications to the project approach may be made as more is learned about the site and the
data needs are refined. A dynamic work strategy is generally used along with real time data evaluation
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and assessment techniques to continually update the CSM as more data becomes available. Continual
revision of the CSM was a key element to the success of the Poudre River project.
2.1 SITE DESCRIPTION
The Poudre River site is located adjacent to the Fort Collins Northside Aztlan Center at 200 Willow Street
in Fort Collins, Colorado. The area of concern is a commercial area comprising approximately 19 acres,
which includes the Northside Aztlan Center, United Way Building, a park, soccer fields, playground, bike
path, and parking areas. The site is bounded on the northeast by the Poudre River, on the northwest by a
branch line of the Union Pacific Railroad, on the southwest by Willow Street and on the southeast by
Linden Street and Pine Street (Figure 1).
The site also includes a historical landfill approximately 12 acres in size. Previous investigations
document landfill debris to be between 9 and 14 feet in thickness with a 1- to 3-foot-thick silty clay cover
(Walsh 200Ib). Two buildings have been constructed on the former landfill. The Fort Collins Aztlan
Center was built in 1973 and the United Way Building was built in 1985. Both buildings are equipped
with methane monitoring systems. Each system has recorded incidences where methane alarms were
triggered, but subsequent testing for methane indicated alarms were not due to actual methane intrusion.
Figure 2 shows the other types of businesses and the expected outline of the historical landfill anticipated
at the time of the TEA.
2.2 SUMMARY OF PREVIOUS INVESTIGATIONS
Previous investigations have summarized analytical results for samples historically collected at the site.
Methane gas surveys were conducted at the landfill for the City of Fort Collins in 1977 by GeoTek, Inc.
and in 1979 by Raymond Vail Associates. The 1977 survey reported methane concentrations ranging
from 0.1 to 4.1 percent gas in 21 boring locations. The 1979 survey reported methane detections in four
out of 27 boreholes. These detections ranged from five to 62 percent of the lower explosive level for
methane, which is five to 15 percent methane gas by volume. The highest levels were found in the
western portion of the landfill. Perimeter locations near residential, commercial, and industrial areas did
not appear to be accumulating methane gas (Walsh 200 Ib).
The Colorado Department of Public Health and the Environment (CDPHE) reported that limited sampling
of soil and groundwater occurred during construction of the United Way Building in 1985. Samples were
analyzed for metals, semivolatile, and volatile organics (Walsh 2001b). In 1995, groundwater was also
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sampled from monitoring wells MW-1, MW-2, and MW-3 (Figure 3). The sample from MW-1 contained
approximately 3,600 micrograms per liter ((ig/L) of naphthalene, 27 (ig/L of benzene, 1,400 (ig/L of
xylene, and other hydrocarbons. MW-1 is located on the southern boundary of the former MGP site. In
addition, chromium was also detected in groundwater in monitoring wells MW-1, MW-2, and MW-3 at
concentrations ranging from 1,130 to 1,250 (ig/L (Walsh 2001b).
In the late 1990s, an underground portion of the western gasholder used by the PVG Company was
encountered during construction of the Burlington Northern Santa Fe railroad spur line (Stewart
Environmental Consultants, Inc. [Stewart] 1996). The underground portion of the gasholder was 10.5 feet
deep, was presumably filled with heating oil when in operation, and was potentially backfilled with waste
oil or coal tar during plant closure. The contents of this gasholder were removed in 1996 by the City of
Fort Collins under the CDPHE Voluntary Cleanup Program. The intact underground portion of the
gasholder was filled with clean soil and left in place. Rail lines now pass over the former location of the
gasholder (Walsh 200 Ib; Stewart 1996). During the 1996 gasholder tank removal, contaminated soil to
the west, south, and east of the gasholder were removed to depths of 3 to 4 feet below ground surface
(bgs). In addition, three test pits were excavated at locations immediately south and east of the gasholder
(Figure 3). Soil containing coal tar, as well as green and blue-green stained soil layers, were observed in
these test pits. Coal tar and other organic compounds were also visible in groundwater encountered in the
test pits. Contaminated soil found at a depth greater than 4 feet bgs and associated groundwater were not
remediated as part of the gasholder removal action (Walsh 2001b; Stewart 1996).
The city installed two monitoring wells (MW-9 and MW-12) on the city's property on the north side of
Willow Street (Figure 3). MW-12 is located downgradient of the location of the former gasholder and
MW-9 is located 200 feet from MW-12, but not directly downgradient of the former gasholder.
Groundwater samples from MW-12 contained levels of benzene in excess of Colorado State drinking
water standards. Groundwater samples from MW-9 contained naphthalene but no detectable benzene
(Walsh 200 Ib).
In 1998, the Larimer County Health Department collected a water sample at a depth of 9 feet bgs from a
sanitary sewer excavation located on the south side of Willow Street. The excavation was adjacent to the
property owned by Schrader Oil Company, which includes part of the property where the PVG Company
was previously located. Tentatively identified compounds detected in this sample included
acenaphthylene, fluorene, phenanthrene, and substituted naphthalene (Walsh 200Ib).
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In 2001, Walsh drilled 11 boreholes (BTH-1 through BTH-11) which became monitoring wells to
evaluate the extent of contamination at the site (Walsh 200 Ib). Soil and groundwater samples were
collected from these boreholes and analyzed for the presence of volatile organic compounds (VOC),
polynuclear aromatic hydrocarbons (PAH), total metals, and dissolved metals. PAHs were detected in
groundwater samples from at least five of the wells, and VOCs were detected in soil samples from three
locations (Walsh 200Ib).
During the 2001 Phase I investigation, contamination was found downgradient of the PVG plant on the
Fort Collins Aztlan Center property (Walsh 200Ib). The nature and extent of soil and groundwater
contamination located on the site are described in several other reports completed by Walsh in 2001 and
2002 under the Fort Collins Downtown River Corridor Brownfields Pilot Assessment Program (Walsh
2001a, 2001b, 2002a, 2002b). Coal tar related compounds, including benzene and naphthalene, were
documented as being present at or above method reporting limits in soil and groundwater on the city's
property. Detected contaminants were found primarily between the locations of the Fort Collins Aztlan
Center, the United Way Building, and the previous location of the eastern most of the two former
gasholders located south of Willow Street. A groundwater plume potentially containing coal tar and/or
fuel related compounds was identified, extending north from Willow Street at least 500 feet onto the
city's property (Walsh 200la, 200Ib, 200Ic, 200Id, 200le, 2002a, 2002b).
Schrader Oil, the company that owns a portion of the property that includes the previous location of the
MGP (Figure 2), is conducting ongoing monitoring and remediation as part of a Colorado Department of
Labor and Employment Oil Public Safety Corrective Action Plan. The Corrective Action Plan was
implemented because of a 1994 leaking underground storage tank and a gasoline groundwater plume
documented on the western and central portion of the Poudre River site and north of the Paragon
Consulting Group, Inc. (Paragon) facilities (Paragon 2004).
In September 2002, UOS identified sheen on the Poudre River along the northern and eastern portion of
the Poudre River site in a shallow section of the river bed during low flow conditions. Globules of coal
tar potentially mixed with fuel related compounds were observed at one location as described in more
detail later in this case study. A sample of water and sheen were collected on September 24, 2002.
Several PAH compounds were detected at low levels in the samples (Walsh 2003). A sample of the
product was also collected from the bottom of the Poudre River by UOS on February 5, 2003. The
product was black/dark brown, viscous, and appeared to have a high surface tension while under water.
When disturbed, the non-aqueous phase liquid (NAPL) dispersed into an oily sheen that rose to the water
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surface. Analytical results document that the product is chemically consistent with products associated
with the PVG plant (Walsh 2002b; UOS 2003).
2.3 SITE GEOLOGY
The site lies in the northeast Front Range of Colorado and a review of previous investigations identified
the site as overlying Post-Piney Creek alluvium from the upper Holocene underlain by older Broadway
alluvium from the Pleistocene (Figure 4). The reported thickness of the alluvium ranged from 5 to 15
feet. Pierre Shale bedrock was reportedly encountered at depths from 16 to 21.5 feet bgs.
2.4 SITE HYDROLOGY
The Poudre River flows along the eastern boundary of the site and flows in a southeastern direction
adjacent to the site. Locally, the river has meandered significantly throughout the history of the site as
evidenced by Sanborn maps collected as part of the Phase I conducted by Walsh (200 Ib). These Ox-
bows or riverbank and channel deposits took on very different configurations over time prior to the
placement of the landfill. It was hypothesized that the deposits could have represented points of
discharge for materials leaving the PVG plant, which was an important consideration in development of
the preliminary CSM. Figure 5 shows the approximate location of the river channels at a time shortly
after the PVG plant was built (1906). A review of additional Sanborn maps from various times after the
PVG was in place indicate that the river continued to migrate over time potentially creating other
depressions or low areas where contaminants from the PVG plant could have been discharged. These
perturbations in the river's path could also represent preferred pathways for the migration of contaminants
from upgradient source areas, beneath the landfill, to the river.
Depth to groundwater at the site was reported to be from 10 to 15 feet bgs with the saturated zone
underlain by a suspected semi-confining Pierre Shale bedrock layer. The reported groundwater flow
direction was to the northeast/east across the site. It was believed that groundwater did not discharge
directly to the river along the eastern edge of the site. Based on available data, it was hypothesized that
the groundwater may have discharged to the river somewhere down river from the site as the known
pieziometric surface began to coincide with the base elevation of the river bed. Direct discharge was
suspected to be the greatest during periods of low flow, but this was considered speculative, and would
need to be confirmed during subsequent field investigations. Any preferred pathways leaving the landfill
or any portion of the site were also identified as potential points for groundwater discharge within the site
boundaries. Based on discussions with the various interested parties and the City of Fort Collins, it did
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not appear that groundwater was being used in the immediate area. According to City officials, water
from the Poudre River is used by the City of Greeley
2.5 MEDIA OF POTENTIAL CONCERN
The media of potential concern at the site included subsurface soil, sediment, surface water, groundwater,
and air (Figure 6). Previous investigations confirmed that upgradient sources resulted in the
contamination of subsurface soil and groundwater beneath the site. Walsh (200 Ib) documented the
potential threat from the volatilization of groundwater plume constituents to indoor air. Previous
investigations had not identified surface water contamination above Maximum Contaminant Levels
(MCL) in the Poudre River adjacent to the site. However, the potential for free product to be in direct
contact with surface water mandated that impacts to surface water be further evaluated during future
investigative activities.
Direct contact with surface soil was not considered a potential pathway of concern because no
observations of contaminated surface soil had been reported. Direct contact with river sediment for
recreational users was identified as a potential pathway of concern along the berm between the landfill
surface and the river, but evaluation of this pathway was beyond the scope of previous investigations and
was only a tertiary objective of the TEA and SA investigations.
2.6 CONTAMINANTS OF POTENTIAL CONCERN
The contaminants of potential concern (COPC) at the site were identified through historical information
and documentation from previous investigations. Primary COPCs at the site include petroleum
hydrocarbons (diesel range organics [DRO] and gasoline range organics [GRO]), BTEX, and PAHs
associated with the coal tar.
Diesel and Gasoline Range Organics. Previous investigations had focused on specific compounds
associated with coal tar such as naphthalene and benzene, so historical information concerning DROs and
GROs was limited.
BTEX Compounds. Previous investigations at the site had also identified a benzene groundwater plume
extending approximately 500 feet northeast from Willow Street between the Aztlan Center and the United
Way building.
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PAHs. PAH compounds such as naphthalene were identified in site groundwater during previous
investigations. Additionally, the analysis of the product sample collected by UOS from the riverbed on
February 5, 2003 revealed that the material contained high concentrations of many semivolatile organic
compounds (SVOC), primarily PAHs. Naphthalene, one of the lightest and most soluble of these
compounds, was chosen to delineate the dissolved plume as well as provide an indication of contaminant
migration pathways or source areas during the TEA. Iso-concentration maps generated from groundwater
data collected by previous investigations indicated a naphthalene plume extending from Willow Street
east to near the middle of the site, but did not indicate that the naphthalene plume was reaching the
Poudre River (Figure 7), as would be expected if the coal tar NAPL plume extended from the former
PVG plant site to the seep area observed in the Poudre River.
Chlorinated Solvents. Previous investigations had not indicated the presence of chlorinated solvents at
the site above MCLs.
Methyl tert-butyl ether. Detections of methyl tert-butyl ether (MTBE) were identified in site
groundwater during previous investigations; however, the groundwater plume was estimated to only be
present in the northwestern portion of the site adjacent to Willow Street.
2.7 EXPOSURE ROUTES AND RECEPTORS
A complete exposure pathway consists of four fundamental components: (1) a source and mechanism of
chemical release, (2) an affected environmental medium and a probable chemical migration process, (3)
an exposure point, and (4) an exposure route by which humans or ecological receptors could come into
direct contact with a COPC. If any of these components is missing, then the exposure pathway is
incomplete and no exposure can occur.
Potential exposure pathways for the site were selected based on current land use and the most probable
future activities at the site, as well as an evaluation of potential transport or uptake pathways.
Prior to the field efforts conducted under the TEA, a pathway receptor diagram (Figure 6) was developed
for the Poudre River site
The most likely receptors and exposure routes were determined to be human recreational users, along
with terrestrial and aquatic organisms exposed to site contaminants via contact with river surface water or
contaminated sediments. Exposures to recreational users of the park, soccer field, and bike path were
considered minor because planned recreational use of the area would not likely require disturbance of
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deeper (subsurface) soil associated with the landfill materials or NAPL. The groundwater to surface
water exposure pathway is considered a potentially complete pathway based on existing information. It
was determined that indoor air inhalation hazards may need further assessment as site reuse is planned
and implemented.
2.8 PROPERTY REUSE SCENARIO
Reuse scenarios were established for the site. Currently, the City of Fort Collins intends to continue the
use of the Aztlan recreational center and the park. The park includes bike paths, playing fields, a soccer
field, and picnic areas. Under the Fort Collins Downtown River Corridor Implementation Program,
redevelopment plans for the site include the construction of a new 50,000 square-foot multi-generational
recreation center.
3.0 SYSTEMATIC PLANNING AND PREPARATION IN SUPPORT OF THE TARGETED
BROWNFIELDS ASSESSMENT
Comprehensive, up-front planning is a key component of the Triad approach. Proper planning coupled
with the use of dynamic work strategies and the correct monitoring and measurement tools will promote
collection of data that will lead to defensible decisions. At the time of characterization, the cleanup goals
for the site are used as the basis for developing a sampling strategy and selecting the appropriate
analytical tools and methods for both sampling and analysis. By understanding the questions that need to
be answered and the data and documentation necessary to make effective project decisions, project
managers and team personnel can use systematic planning as a tool to develop a roadmap to success.
In May 2003, EPA issued a TEA grant to evaluate the potential for official landfill closure. As previously
stated, the ultimate objective of the TEA was to facilitate the construction of a new community recreation
center on the city's property and identify the source of coal tar and sheen identified in the Poudre River.
Contractor support to EPA Region 8 was provided under the START 2 contract, initially by UOS and
subsequently by Tetra Tech.
The BTSC provided support to EPA Region 8 and Tetra Tech, during project planning, including the
development of a revised work plan and approach for the TEA, which incorporated the Triad approach
(Tetra Tech 2003). The initial work plan developed by UOS was never completed or formally submitted
for EPA review because it was decided early on to abandon the stated approach and move toward an
investigation based on TEA and Triad principles. The elements of the initial plan did not receive full
review by EPA and are described here as background information only.
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3.1 INITIAL WORK PLAN
This section describes the activities originally identified under the TEA using a traditional Phase I and
Phase II approach with fixed laboratory analyses. The original technical approach for this site was based
on standard industry practices and American Society for Testing and Materials standards for conducting
Phase I and Phase II SA investigations. Clarifications and modifications to the scope were discussed at
scoping meetings between EPA, Tetra Tech, and legal and technical representatives for potentially
responsible parties (PRP).
3.1.1 Site-Specific Objectives for Initial Work Plan
The original objective for the site TEA was to conduct an investigation to determine the source of the
sheen and the product identified in the Poudre River. The Phase II work plan also called for investigation
of the former landfill to evaluate the potential for formal closure of the landfill from the CDPHE. The
data collected during this investigation was expected to complement a previous Phase I investigation
conducted by Walsh at the site.
3.1.2 Development of the Original Sampling Approach
The original, pre-Triad sampling plan called for collection of authoritative judgmental samples to confirm
the presence or absence of contamination at locations where previous reports had implied potential
contaminant migration pathways for coal tar related compounds. Samples were to be collected using a
Geoprobe® direct-push drill rig. The focus of the investigation was on the identification of preferential
contaminant migration pathways such as paleochannels or topographic lows within the bedrock. The
following primary activities were planned for the original Phase II SA investigation:
• Characterize site soil via direct-push sampling by collecting 20 surface soil samples and 27
subsurface soil samples (and associated quality control [QC] samples) and conducting off-site
laboratory analyses for the identified COPCs
• Characterize site groundwater via the installation of seven standard monitoring wells and off-
site laboratory analyses of 13 groundwater samples (and associated QC samples) for the
identified COPCs
• Characterization of additional grab samples of coal tar and any other NAPL found during the
investigation using standard methods and off-site analyses for the identified COPCs
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3.1.3 The New Sampling Approach
In May 2003, EPA directed Tetra Tech to prepare a revised field sampling plan (FSP) for the TEA at the
site based on principles of the Triad approach. The revised FSP was finalized in July 2003 and described
field activities to be conducted to identify chemical characteristics of the coal tar material identified in the
Poudre River adjacent to the site, evaluate the nature and extent of contamination at the site that could
impact reuse or remedy design, and identify pathways for the coal tar material or other contaminants
reaching river.
To streamline site characterization activities, project goals were reexamined and potential investigation
design modifications identified. To the degree possible, the project team agreed that innovative
technologies and approaches should be used to maximize the efficiency of more traditional methods of
investigation. In particular, the use of geophysical methods and the EPA Region 8 Mobile Laboratory
were identified as potential ways to maximize data collection efficiency. The BTSC examined the
following project elements in an effort to redesign the program:
• The preliminary CSM to identify critical data gaps
• The proposed soil and water sampling and analytical programs to identify methods for cost
effectively increasing sampling and analytical data density
• Other sources of information that could be obtained using innovative technologies to evaluate the
potential for impacts from fugitive emissions and discharge of groundwater to surface water
• Alternative non-intrusive methods for identifying potential preferred pathways for contaminant
migration
The new sampling approach developed as part of the reevaluation effort included the identification of a
dynamic work strategy that incorporated the use of several field-based technologies to be used in refining
the CSM. To provide evidence of preferential pathways for the subsurface migration of contaminants and
to identify any buried metal objects such as drums that could act as potential sources, a geophysical
survey was conducted using terrain conductivity meters. The geophysical survey was initiated prior to
conducting any intrusive sampling the site. Potential pathways identified for evaluation included,
discharge pipes, bedrock channels, former river channel features, buried objects, and dumping grounds.
In addition to the geophysical survey, the project team, with support from one of the PRPs, undertook the
sampling of all existing wells across the site and the collection of water level data to improve the team's
understanding of hydrogeologic conditions and water quality. In addition to these activities, the project
team planned to use direct-push groundwater sampling and analysis of the samples in near real time using
the Region 8 Mobile Laboratory to increase the density of groundwater data and provide the results to the
team in a shorter timeframe.
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By using this approach instead of the traditional well installation approach, the density of sampling points
was increased from seven wells and associated samples to more than 30 sampling locations with up to
three sampling intervals per direct-push location. The cost savings was to be further enhanced by
substituting small gauge temporary monitoring wells for groundwater sampling purposes where possible
instead of larger, permanent monitoring wells; particularly where no contamination was found. Direct-
push groundwater results and the other information obtained during the geophysical survey and existing
monitoring well sampling event would then be used to optimize placement of permanent groundwater
monitoring locations. Grab groundwater samples were analyzed for VOCs using a field-based gas
chromatography/mass spectrometry (GC/MS) to guide the direct-push sampling program and identify
samples for off-site analysis of PAHs and other potential COPCs not measured in the field. Appendix 1
contains Technology Quick Reference Sheets (TQRS) for each real-time technology used at the Poudre
River site.
3.1.4 Analytical Options
Under the dynamic work strategy applied at the site, the use of real-time analytical results for decision-
making allowed the investigation to focus on areas where elevated levels of contamination might be
expected in a single mobilization.
For the purposes of this investigation, a modified SW-846 8260 method for the on-site analysis of VOCs
was used to guide the direct-push sampling program. In addition to the on site GC/MS, a photoionization
detector (PID) in series with a flame ionization detector (FID) was used to screen soil and groundwater
samples to identify locations where preferential contaminant migration pathways or potential source areas
might be located. Figure 8 provides the dynamic work strategy logic used to collect groundwater grab
samples in the field. It should be noted that at several locations multiple samples from differing depths
were taken, regardless of the results obtained from the initial sample collected at or slightly below the
surface of the water table, to assure the team would not miss a deeper zone carrying contamination, which
was not identified at the top of the water table.
The project team also concluded that a DMA was needed to ensure that the modified SW-846 Method
8260 analyses would provide identification of indicator compounds, in particular naphthalene, and
provide method and matrix specific limits of detection. Indicator compounds such as BTEX and
naphthalene in the dissolved phase would provide information on areas where the NAPL and coal tar
related compounds could be expected. Evaluation of site-specific matrices and the corresponding
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detection/reporting limits was conducted to ensure that the information provided by the mobile laboratory
was of sufficient quality and that the detection/reporting limits were low enough to guide project
decisions. The DMA consisted of an initial groundwater sampling event at the site using GC/MS analysis
in the field to evaluate volatile target compounds expected at the site, achievable detection and reporting
limits, development of an initial calibration curve and continuing calibration procedures, and finally
evaluation of any site-specific matrix interferences. The DMA is discussed in further detail in Section
3.2.
3.1.5 Developing Decision Logic
Development of decision logic provides a clear process for how and when collection of samples for field
and off-site analysis might be best used. A decision logic diagram (Figure 8) was developed prior to
field work to provide field sampling personnel with a step-by-step process for screening direct-push soil
and groundwater samples in the field. Using the decision logic diagram, the field team could identify
locations where samples taken from the top of the water table indicated the necessity for collection of
samples at the bedrock interface. Through this logic the field team was able to assess small-scale
heterogeneity of dissolved contaminants at various depths and identify areas where the presence of coal
tar NAPL at the bedrock interface was likely.
3.2 GRAB GROUNDWATER SAMPLING DEMONSTRATION OF METHODS
APPLICABILITY
The DMA coincided with the collection of groundwater samples from 16 existing monitoring wells at the
site. The samples were analyzed in the field using a modified SW-846 Method 8260 analysis. Based on
stakeholder consensus, additional volume was sent to off-site laboratories for the analysis of VOCs,
SVOCs, pesticides/poly chlorinated biphenyls (PCB), dissolved metals, cyanide, GRO, DRO, and anions.
Water level measurements at all monitoring well locations were also collected to help refine the CSM and
develop a site-wide groundwater surface map.
The collection of VOC data enabled the field team to determine applicable detection and reporting limits
for field-based GC/MS results, design an initial calibration and appropriate QC protocol, and evaluate the
types and concentrations of contaminants expected in groundwater at the site. These data were then used
in conjunction with the geophysical survey to refine the CSM, the direct-push groundwater and soil
sampling scheme, and focus drilling in areas where coal tar NAPL was suspected.
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3.3 TARGETED BROWNFIELDS ASSESSMENT FIELD EVENT
The TEA field activities included a geophysical survey followed by a direct-push groundwater grab and
soil sampling investigation and finally, installation, development, and sampling of temporary and
permanent monitoring wells. During site activities, portions of the site were closed to the public and
access to the Poudre River was restricted.
3.3.1 Geophysical Survey
Prior to conducting any field sampling activities under the TEA, a geophysical survey was conducted at
the site. The purpose of the survey was to provide evidence for preferential pathways for the subsurface
migration of contaminants using geophysical techniques. Such pathways include (but are not limited to)
discharge pipes, bedrock features, and subsurface features such as paleochannels.
Early on in the fieldwork planning process, the project team identified the potential configuration of the
bedrock beneath the site based on a map provided in UOS's draft work plan that was created using boring
logs. This map showed a steep dip in the bedrock beneath the site extending east toward the Poudre
River. A review of the boring logs from the site suggested, however, that the information that served as
the basis for this map was not very definitive because many borings did not extend to the shale bedrock;
therefore, the boring logs do not show the shale bedrock. It was the BTSC's contention that the bedrock
surface indicated on Figure 5 could be more representative of refusal than a geologic feature beneath the
site. Refusal of direct-push or auger rigs has many causes including; the presence of trash, gravel zones,
and metal objects. Therefore, the team decided to perform a geophysical survey to better refine the
bedrock surface map and consequently the CSM.
The geophysical field team used two instruments for this investigation, the Geonics Limited EMS 1 and
EM34 Terrain Conductivity meters. Both instruments measure electrical terrain conductivity by
transmitting electromagnetic energy into the subsurface. This is termed an apparent electrical
conductivity reading because the instruments measure a "bulk electrical conductivity," which is a
measurement of the terrain's ability to carry electrical energy. This measurement may be influenced by
lateral or vertical changes in the subsurface. The transmitted electromagnetic field induces eddy currents
into the subsurface and the electromagnetic field carried by these currents are sensed by the receiver coil
of the instrument and transmitted to the control box where they are amplified and tuned to read in the
proper conductivity units, milliSiemens per meter (mS/m). It is a useful measurement, since finer
particulate soil and high clay content soil can be distinguished from sands and gravelly soil, bedrock
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features including paleochannels can be mapped, and buried metal such as pipes and drums can be
located.
The EM31 was used to investigate the shallow subsurface, or unsaturated zone, since it has an affective
exploration depth of approximately 12 feet with a fixed coil spacing of 3.7 meters. The EM 34 was used
because the transmitter and receiver coil spacing can be varied in this instrument to obtain better targeted
depth resolution, allowing the effective exploration depth to be increased and "tuned" to a targeted depth.
A 10-meter coil spacing was used to investigate the saturated zone at the site. The instrument was set in
the vertical dipole mode (coils placed horizontally on the ground) giving it a peak response from materials
from approximately 3 to 7 meters bgs (10 to 20 feet). The average groundwater depth at the site is
approximately 15 feet. A 20-meter coil spacing was used to investigate possible bedrock features, since
in this configuration, the instrument has a peak response from materials from approximately 6 to 12
meters bgs (20 to 30 feet). Bedrock at the site is up to 21 feet bgs.
The TEA geophysical survey was performed from June 26 through June 29, 2003. On June 26, the
project team laid out survey lines with wood stakes and flagging spaced 20 feet apart in an area measuring
approximately 500 feet by 600 feet, parallel to the River (Figure 9). The survey started at the north corner
of the property using the EM31 instrument. Measurements were recorded in a data logger along the
survey lines approximately every 2 feet for good lateral resolution. The planned EM31 survey was
completed that day. After evaluation of the data, the team decided to expand the survey in the northwest
direction. The survey expansion was completed the following day, June 27, 2003.
The EM34 survey was performed on June 28 and June 29, 2003. The survey was performed using both
the 10 meter and 20 meter receiver and transmitter coil spacing both set on the vertical dipole
configuration to minimize near surface metal interference and maximize exploration depth. The survey
was performed with the coils parallel to the direction of the survey. The 10 meter coil spacing survey was
performed by taking readings every 10 feet along the survey lines, and the 20-foot coil spacing survey
was performed by taking readings every 20 feet along the survey line.
For ground control, the field team used the fixed surveyed points of several permanent monitoring wells
to fix the survey line points. Global Positioning Satellite readings were taken at well locations and tied to
geophysical stake nodes in order to translate the geophysical grid into site coordinates such that the results
could be plotted on existing investigative maps.
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3.3.1.1 Geophysical Survey Results
Data were downloaded onto a computer and compiled into color contour maps using Geosoft Oasis
Montaj® contouring and mapping software for presentation. The EM34 data were further processed by
despiking readings from near surface metal to enable conductivity trends to be visualized more easily.
Figure 10 provides an example of the geophysical survey results from the EM geophysical survey.
The EM31 and EM34 terrain conductivity surveys provided information to map the subsurface of the site.
Variations in apparent ground conductivity were detected, suggesting that on-site fill materials are
variable. These data supported the observed variance in groundwater movement. The range in apparent
conductivity in the unsaturated zones indicated by the EMS 1 data is from less than 8 to over 20 mS/m. In
general, the lower apparent conductivity materials are located at the northwest half of the site. The range
of conductivities here would suggest loose fill, sand, and other porous materials (such as landfill debris).
The higher conductivity areas of the southeast portion of the site nearer the buildings suggest engineering
fill and fine-grained soil such as clay or clayey silts. In the vadose zone, groundwater movement would
be more hindered in this area than in the looser fill of the northwest. This interpretation is also supported
by the well logs, which show landfill debris mixed with gravelly sands at shallow depths in well log SB-
05 in the low conductivity area, and thick clayey silts mixed with a lesser degree of landfill debris in the
boring SB-01 in the high conductivity area south of the playground.
The EM34 data showed higher apparent conductivity ranging from approximately 14 to 30 mS/m in the
northwest half of the site. This is likely due to the influence of higher conductivity from the saturated
zone. Also, the higher apparent conductivity trends seen in the EM31 survey color contour map (Figure
10) become less prominent in the EM34 presentation. This was suggestive of the presence of looser, less
conductive gravels and sands at greater depths. This finding is also supported by the boring log SB-01,
which shows sandy gravels at depths greater than the exploration depth of the EM31. Also, the influence
of bedrock topography becomes apparent with analysis of the EM-34 data. The EM34 maps indicated an
apparent conductivity high trend at the east quadrant of the site near the river, which correlated very well
with the bedrock topography contours. This feature suggests an expected increase in thickness of sandy
gravel materials near the river bed.
An important finding from the EM geophysical survey was the relatively low volume of metal objects that
were indicated within the former landfill. The most prominent feature was the water main that parallels
the river near the bank at the east edge of the site. The service pipes at the northwest edge of the surveyed
area were also detected in the geophysical survey data. No other pipes were interpreted to be present, but
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there was a suggestion of pipe signatures that paralleled the service pipes approximately 100 feet to the
south, as shown on Figure 10.
3.3.1.2 Geophysical Survey Conclusions
The geophysical data combined with boring log correlations suggested that groundwater movement in the
unsaturated zone is influenced by the variability of materials ranging form tight clays to sands, gravels
and landfill debris. The groundwater movement is probably largely influenced by bedrock topography in
the saturated zone where materials are primarily sands and gravels that would not hinder groundwater
movement. Any preferential pathway for contaminant migration is shallowly dipping and sloping to the
east where the gradient of the bedrock surface is greatest. There also may be a channeling of groundwater
along the linear feature as shown in the geophysical data across the northwest section of the site towards
the northeast. However, this did not appear to be directly connected to the seep area.
There appeared to be no piping directly connected to the seep area. The geophysical survey defined
service lines and the main water line very well, and may have identified a small pipe going across the site.
However, if this is a pipe, it appears to not correlate with the seep area. The EM geophysical survey
identified an apparent buried metal anomaly south of the seep area, which was largely masked by the
presence of the water main (Figure 11). This area was reexamined during the subsequent SA using high
resolution resistivity and invasive drilling techniques (see Section 7.0), and no large metal objects or
source areas could be confirmed in the area.
3.3.2 Direct-Push Soil/Product Sampling
Following the TEA geophysical survey a direct-push sampling event was conducted. All boreholes were
continuously cored and logged for lithologic description, and screened with a PID/FID. As planned in the
decision logic diagram (Figure 8), where PID/FID readings exceeded 100 parts per million (ppm) or
where visual inspection of soil cores indicated NAPL, a sample of the soil was collected and analyzed on
site for VOCs using a modified SW-846 Method 8260 analysis. Another aliquot of the soil from the same
interval was sent to an off-site laboratory for comparative analysis.
Eight soil samples (excluding the delineation soil samples, described below) were collected during this
portion of the field activities. Two soil samples each were collected from monitoring well boreholes FC-
MW-01, FC-MW-09, and FC-MW-15. One soil sample was collected from the monitoring well borehole
FC-MW-12 and one from monitoring well borehole FC-MW-13. These soil samples were sent for off-
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site analysis of SVOCs, VOCs, pesticides/PCBs, and DRO. These product data were later used to
fingerprint the material in the source area adjacent to the former MGP for comparison with product found
in the river as described in more detail in Section 3.3.7.
3.3.3 Coal Tar Product Delineation
Where coal tar product was encountered in soil boring FC-GW-15, near the Poudre River, additional
borings were installed at 20-foot spacing around the location to assess the lateral and vertical extent of the
coal tar NAPL and to evaluate relative potential NAPL impacts to the river.
Delineation boreholes were installed 20 feet north, south, east, and west of borehole FC-GW-15. PID
readings were less than 30 ppm at each of the delineation borings. However, FID readings varied from
less than 90 ppm to greater than 1000 ppm. It was suspected, but not confirmed, that the presence of
methane was causing the high FID readings. The high FID readings were not sustained and lasted only a
few seconds before dropping. No identifiable odors were detected in any of the delineation cores. Some
black staining was observed at location FC-DS-02, which is 20 feet west of FC-GW-15. A soil sample
was collected from 3 to 5 feet bgs at this location and sent for off-site laboratory analysis of SVOCs,
VOCs, pesticides/PCBs, and DRO. Delineation sampling did not identify the presence of product at any
of the four additional boreholes indicating a localized area of contamination at 17 to 18 feet bgs at FC-
GW-15.
3.3.4 Direct-Push Groundwater Sampling
The TEA FSP (Tetra Tech 2003) estimated that a maximum of 90 groundwater grab samples from up to
45 different direct-push borehole locations would potentially be collected. A total of 48 groundwater grab
samples were actually collected from 34 of the 42 locations where the direct-push tool was successfully
advanced into the subsurface to groundwater. In the other eight locations, the direct-push rig met refusal
prior to reaching groundwater. The high incidence of refusal at the site was initially attributed to landfill
debris and a potential sandstone layer within the alluvium. Because refusal was not a significant issue
during the limited subsurface investigations conducted previously at the site using hollow-stem auger
(HSA) drill rigs, the high incidence of refusal encountered during the TEA was not anticipated. Figures
12 and 13 include the direct-push borehole locations where samples were proposed for collection.
Forty eight groundwater grab samples were analyzed for VOCs on site; additionally, sample aliquots from
FC-GW-15 and FC-GW-33 were sent to off-site laboratories for analyses of suspected fuel-related
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compounds in accordance with the established TEA decision logic (Figure 8) because a visual inspection
of the sample indicated the presence of NAPL.
During the direct-push sampling program, visible NAPL resembling coal tar was only encountered at 17
to 18 feet bgs, at FC-GW-15 (Figure 12) located in the southeast portion of the site near the Poudre River.
In an attempt to fingerprint the NAPL found in groundwater samples at this location, water was decanted
from an extra 1-liter amber bottle at the laboratory and the remaining NAPL was solvent rinsed from the
bottle. This resulted in approximately 4 grams of the NAPL product for extraction, which was submitted
for analysis of SVOCs and pesticides/PCBs. The laboratory was able to analyze the extract for SVOCs at
a relatively high dilution, however, due to the large number of non-target compounds the pesticide/PCB
analysis could not be completed on the extract.
3.3.5 Monitoring Well Sampling Results
Five temporary and 10 permanent small-gauge monitoring wells were installed as part of the TEA field
effort. Locations for the wells were identified based on field analytical results from the direct-push
groundwater grab samples. After review of the grab sample field-based analytical results, the wells were
installed at locations surrounding the landfill where the highest grab sample VOC concentrations were
detected using the on-site GC/MS. Figures 12 and 13 include the locations of all temporary and
permanent monitoring wells installed during the TEA investigation.
After installation, the monitoring wells were developed and sampled according to procedures described in
the TEA FSP. Groundwater samples were analyzed at off-site laboratories for SVOCs, VOCs,
pesticides/PCBs, dissolved metals, cyanide, DRO, and anions. Groundwater samples from newly
installed groundwater monitoring wells were analyzed for the same constituents as existing upgradient
monitoring well samples.
Results for all detected VOC and SVOC compounds are provided in Tables 2 and 3. Analytical results
for pesticides, PCBs, cyanide, metals, and water quality parameters are not provided because these results
yielded no reportable quantities, were not indicative of contamination, or were not above regulatory
thresholds. The results of the TEA confirmed the existence of BTEX compounds in site groundwater.
Benzene concentrations are highest in the southern portion of the Aztlan Center parking lot and east of
Willow Street between the railroad spur to the north and Pine Street to the south.
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For the TEA, existing monitoring wells and locations where NAPL product was visually identified were
analyzed for DRO. The highest concentrations of DRO were detected in groundwater collected from
wells in southern portions of the parking lot for the Northside Aztlan Center and just east of Willow
Street adjacent to Giddings machine shop. These sampling locations are downgradient of the historical
MGP location.
Although previously unreported, chlorinated solvents were detected in a significant number of
groundwater samples across the site. The most prevalent chlorinated solvent detected was PCE, which
was detected in the eastern portion of the site, along the Poudre River, and, predominantly, in the
southeastern portion of the site near the United Way building (Figure 13).
Iso-concentration maps were created to provide a visual representation of some site contaminants in
groundwater. These maps were created using the TEA field and off-site data, as well as historical
observations. The contaminants: naphthalene, MTBE, and PCE were chosen based on the high frequency
of detection. In order to further refine the site CSM and assist in the delineation of the groundwater
plume, benzene was also mapped. Naphthalene was chosen as an indicator of PAH contaminants related
to coal tar contamination (Figure 12).
3.3.5.1 Naphthalene in Groundwater
Figure 12 shows the concentrations of naphthalene in groundwater based on the results of the TEA. A
review of Figure 12 shows concentrations of naphthalene in groundwater are highest in the area of the
historical gas holders on the property of the former MGP west of Willow Street and downgradient of that
location in the Aztlan Community Center parking lot. The plume generally follows the flow direction of
groundwater at the site east and northeast towards the Poudre River.
Groundwater data from previous investigations conducted at the site indicated that the naphthalene plume
extended east from Willow Street to the area of the playground located south of the Aztlan Community
Center (Figure 7); however, the TEA investigation indicated that the naphthalene plume extended as far
as the Poudre River (Figure 12). Naphthalene concentrations near the Poudre River however, were far
lower than might be expected in groundwater at equilibrium with coal tar NAPL, and a significant data
gap still existed between the Aztlan Community Center parking lot and the river. Therefore, the project
team still faced considerable uncertainty concerning the location of any preferred pathway for coal tar
NAPL migration to the river.
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3.3.5.2 MTBE in Groundwater
MTBE was also detected in site groundwater during the TEA. Results from on-site analysis using a
modified SW-846 Method 8260, off-site EPA Contract Laboratory Program VOC analyses, and Method
8260 analyses conducted at the EPA Region 8 laboratory all indicated the presence of MTBE in various
groundwater samples. This highly soluble VOC target compound is not a component of coal tar
contamination associated with the historical MGP. The highest concentrations of MTBE were observed
along the western portion of the property adjacent to Willow Street. The highest detection of MTBE in
groundwater (83.9 (ig/L) from the TEA was located at FC-GW-34 (Figure 12). This direct-push location
corresponds to past gasoline releases that have been documented on an upgradient adjacent property.
Additional detections were found along the river near monitoring well FC-MW-04 providing evidence
that the MTBE dissolved plume may extend to the river.
The presence of MTBE in site groundwater, particularly west of the Northside Aztlan Center parking lot,
indicated that past gasoline spills in the area west/northwest of the property have migrated to the property.
The presence of this contaminant suggested that more recent fuel-related spills may have commingled
with coal tar from the historical MGP and subsequently may have enhanced the mobility of coal tar
NAPL in the area.
3.3.5.3 Tetrachloroethene in Groundwater
Previous investigations at the site had not identified widespread PCE contamination on the property. A
review of Figure 13 shows that detections of PCE are widespread in the area around the United Way
Building with concentrations increasing south and east of this facility. The highest concentration of PCE
in groundwater detected during the TEA was 42.1 (ig/L at location BTH-10. The source of PCE was not
identified during the TEA, although the subsequent SA investigation provided more information
regarding potential source areas in this portion of the site (see Section 7.0).
3.3.6 Surface Water and Sediment Sampling
The initial sampling decision logic outlined in the FSP and Quality Assurance Project Plan for the TEA
did not include the collection of river sediment or surface water samples. However, observations of a
sheen and coal tar-like NAPL in the river in conjunction with relatively low stream flow allowed several
samples of opportunity to be collected during the field sampling event. Three surface water samples
(samples SW-1 through SW-3) and six sediment samples (samples FC-RS-01 through FC-RS-06) were
collected from the river to evaluate potential impacts of the observed NAPL. Surface water and stream
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sediment sample locations are included on Figures 12 and 13. Sample aliquots for both the surface water
and sediment were collected for off-site analysis of VOCs, SVOCs, pesticides/PCBs, and GRO.
3.3.7 Product Fingerprinting
The origin of coal tar NAPL detected in the Poudre River adjacent to the Northside Aztlan Center in Fort
Collins has been a major point of contention among interested parties including, Xcel Energy, Schrader
Oil, and the City of Fort Collins. In an attempt to "fingerprint" the material found in the river, Tetra
Tech, as tasked by EPA under the START 2 contract, evaluated the relative distributions of PAH
compounds in four riverbed samples versus those found in three upgradient potential source area samples.
The PAH analytical results for samples used in the fingerprinting evaluation are provided in Table 4.
Sample results are compared to benzo-a-pyrene as a means to evaluate the relative ratios of constituents
found in each sample. The results of the product fingerprinting are presented in Appendix 2. Table 5
shows the physical properties of a product sample. The physical properties of product can be critical to
understanding the fate and transport tendencies of the material and can influence the remedial design at a
site.
3.3.7.1 Product Samples Collected from the Poudre River
In September 2002, a sheen was noticed on the river near the south bank, in line with the axis of the
identified plume of suspected coal tar related compounds. A sample of the NAPL (FC-PR-01) was
subsequently collected from the bottom of the river by UOS on February 5, 2003. The product was dark
brown to black, viscous, and appeared to have a high surface tension while under water. When disturbed,
the NAPL dispersed into an oily sheen on the water surface. A second sample of the NAPL product, (FC-
PS-01) was collected in September 2003 from the river bottom near the location of the FC-PR-01 seep
area by Tetra Tech during the course of the TEA.
After the TEA was completed, additional NAPL samples were collected and added to the correlation
analysis as well. NAPL sample PR-SB-8 was collected from a temporary well screened in bedrock within
the river channel during the river channel investigation conducted by one of the PRPs (Xcel Energy) and
their consultant RETEC (see Section 6.0; RETEC 2004; and Figure 14). This sample (PR-SB-8) was
collected approximately 17 feet into bedrock from the bottom of a temporary well screened from 9 to 19
feet bgs. Bedrock at this location (PR-SB-8) began at 2 feet bgs. Finally, a soil sample (TR-01SP)
containing visual NAPL contamination was collected from Trench-01 (see Figure 14) at the bedrock
interface approximately 2 feet bgs during the same PRP river channel investigation.
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3.3.7.2 Samples Collected from Potential Upgradient Sources
Upgradient samples were chosen based on historical visual observations identifying NAPL product. The
first upgradient soil sample was collected from a test pit at the former MGP site (Figures 2 and 3). The
product sample (TP-2, 11.5') was collected from 11.5 feet bgs at test pit 2 during the gasholder
investigation conducted by Western Environmental Technologies, Inc. (Western) in 1996 (Western 1996).
Two additional product samples were collected from areas in the former landfill to evaluate the potential
for sources of the material found in the river at these locations. Two locations were identified where
limited product was encountered in the former landfill materials; however, additional delineation efforts
did not yield product from nearby boreholes. Upgradient product sample [BTH-10 (5-15')] was collected
by Walsh at location BTH-10 (Figure 3) during an investigation in 2001 (Walsh 200 Ib). Upgradient
product sample (HI250) was collected by Tetra Tech between 17 and 18 feet bgs at direct-push borehole
FC-GW-15 during the 2003 TEA (Tetra Tech 2004a).
3.3.7.3 Correlations of PAHs in River and Upgradient Samples
Tetra Tech used a statistical software package (STATISTICA™), to develop correlations between
concentrations of PAHs in targeted samples collected in the Poudre River and from potential upgradient
sources. In accordance with EPA guidance (EPA 2000), a proxy value of one half the quantitation limit
was used for non-detected values. Results were normalized to benzo(a)pyrene to represent PAH ratios in
each sample rather than absolute values. Correlations calculated for absolute values produced similar
results. Correlation coefficients closer to 1 imply a strong relationship between the concentrations of
PAH compounds in the samples. Values of correlation coefficients closer to zero imply little correlation
between variables.
The high correlations (correlation coefficients of 0.94 to 0.98) between the concentrations of PAH
compounds detected in the riverbed samples and in the former MGP sample (TP-2, 11.5') suggest that the
PAHs found in these samples have a common origin and were generated by a common process (Appendix
2).
Samples collected from landfill materials (BTH-10 [5-15'] and H1250) had extremely poor correlations
(0.01 to 0.10) when compared to the riverbed samples, indicating that these materials have a very
different composition and do not have a common origin. Samples collected from the landfill materials
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also had low correlation coefficients (-0.009 to 0.03) when compared to the MGP sample (TP-2, 11.5'),
indicating that these materials have a very different composition and do not have a common origin.
3.3.7.4 Ratios of PAHs in River and Upgradient Samples
In addition to the correlations and scatterplots developed using the statistical software package
(STATISTICA™), Tetra Tech developed bar/column plots for the evaluation of PAH ratios. Bar charts
were completed using absolute concentrations of PAHs contained in riverbed and upgradient samples. In
accordance with EPA guidance (EPA 2000) a proxy value of one half the quantitation limit was used for
non-detected values. Bar charts are provided in Appendix 2 of this case study.
Four visual comparison bar charts were created comparing PAH ratios for riverbed samples and each of
the three upgradient samples. A review of the PAH ratio comparison for river samples versus the MGP
sample reveals very similar patterns. Both the river samples and the MGP sample have PAH
concentrations where the highest concentrations are of naphthalene followed by phenanthrene,
acenapthylene, and fluorene. Concentrations of the remaining 12 PAH compounds found in the river and
MGP samples are comparatively low.
A review of the PAH ratio comparison between the river samples and landfill material sample BTH-10
(5-15') reveals very different patterns. Landfill material sample BTH-10 (5-15') has PAH concentrations
where the highest is pyrene, followed by relatively high concentrations of benzo (b) fluoranthene, benzo
(a) pyrene, acenapthylene, fluoranthene, and phenanthrene. Concentrations of the remaining 11 PAH
compounds are also elevated relative to the highest concentration compound of pyrene. Sample BTH-10
(5-15') also has a low concentration of naphthalene relative to the remaining PAH compounds. This is in
direct contrast to the MGP sample and all of the river samples where the predominant PAH compound in
the sample is naphthalene.
Similarly, a review of the PAH ratio comparison between the river samples and landfill material sample
H1250 reveals very different patterns. In landfill material sample H1250, the highest concentration PAH
is pyrene, followed by relatively high concentrations of benzo (b) fluoranthene, benzo (a) pyrene,
acenapthylene, fluoranthene, and phenanthrene. Concentrations of the remaining 11 PAH compounds are
also elevated relative to the highest concentration compound of pyrene. Sample HI 250 also has a very
low concentration of naphthalene relative to the remaining PAH compounds. This is in direct contrast to
the MGP sample and all of the river samples where the predominant PAH compound in the sample is
naphthalene.
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3.3.7.5 Summary Of PAH Correlation Findings
Both the scatter plot correlations and the bar/column plots for PAHs indicated that the material found in
the PVG sample and those samples collected in the Poudre River were very similar in composition and
may have a common origin or have been generated by a similar process. PAH ratios for other potential
source materials, including localized free product and heavily contaminated soil samples collected within
the historical landfill materials, correlated very poorly with the material collected at the former MGP and
the river samples. Given the extremely strong correlations between the PVG sample and all four samples
collected over a period of more than 1 year from the Poudre River, it is considered likely that these
materials have a common origin. The PAHs found in other free product materials identified during the
field activities of the TEA and SA appear very different in composition from both the MGP sample and
all four river samples indicating that it is very unlikely that these materials are the source of the river
contamination.
4.0 REVISED PRELIMINARY CONCEPTUAL SITE MODEL
At the conclusion of the TEA, the results were compiled and the CSM was once again refined to reflect
the latest knowledge concerning the site (Figure 15). A hypothesis was proposed, which stated that
interbedded caliche and/or cemented sandstone layers within the alluvium might be present across the site
based on the high frequency of drilling refusal encountered during the TEA investigation. The identified
presence of petroleum hydrocarbons and contaminants associated with more recent gasoline and diesel
fuels during the TEA was also included. Finally, potential locations of coal tar NAPL sources and
migration pathways were included; their identification was the major question remaining at the site and a
primary objective of subsequent investigations.
The project team further hypothesized that either the coal tar NAPL was screened away from the shallow
groundwater by some physical barrier downgradient of the former MGP site, or the pathway was not
complete between the former MGP and the river. This hypothesis was based on the low concentrations of
dissolved phased NAPL-associated contaminants identified in groundwater at downgradient areas of the
site. If a complete pathway did not exist between the former MGP and the river, then the coal tar NAPL
observed there could be the result of some type of dumping scenario in or near the river. These
observations prompted one of the PRPs, Xcel Energy, to initiate a river channel investigation and a
drilling program around the banks of the river in an attempt to identify localized sources that could be a
source for the coal tar contamination identified in the river.
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5.0 RIVER CHANNEL INVESTIGATION
An obvious source for the coal tar NAPL in the Poudre River and a complete pathway for coal tar
migration from the former MGP to the river was not identified during the TEA. As a result, one of the
PRPs, Xcel Energy, implemented a river channel area investigation in an attempt to identify the extent of
the seep and the potential presence of localized source areas other than the former MGP itself. Xcel
Energy's consultant, RETEC, conducted the investigation with oversight provided by Tetra Tech for EPA
Region 8. The area of interest extended from near monitoring well BTH-15 and north along the riverbed
to the railroad trestle (Figure 3).
5.1 Proposed Revisions To The Conceptual Site Model
The CSM proposed by Xcel Energy and their consultant RETEC, predicted that coal tar had been dumped
in the Poudre River itself and/or it had been dumped in the former landfill adjacent to the seep area, and
that no complete pathway for coal tar NAPL migration existed between the former MGP and the Poudre
River. This CSM had extensive implications concerning the responsibility for cleanup and any potential
remedy proposed for the site. If the source material was localized to the river channel, it should be
possible to dig it out and simply backfill the portion of the impacted river channel. If the contamination
observed in the river was the result of coal tar dumped within the landfill, then the City of Fort Collins
could be identified as a PRP for the cleanup of the source material within the landfill and the
implementation of any mitigation efforts.
If the source was found to be continuous and coupled with the former MGP, then the remediation of the
river sediment would likely have to be accompanied by a mitigation effort to keep the coal tar NAPL
from reentering the river channel. The EPA was skeptical of the suggestion that there was a localized
source responsible for the observed contamination present in the river, but the discontinuous nature of the
observed dissolved plume suggested that the potential for the presence of a localized source area clearly
existed.
5.2 River Channel Investigation Activities
Based on the proposed revisions to the CSM as described above, Xcel Energy and RETEC decided to
begin a parallel investigation in the immediate vicinity of the river channel. Although EPA provided
suggestions for work plan enhancement, the PRP work plan was not developed by EPA and did not
follow the principles of the Triad approach. EPA also continued preparation of work plans to support a
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more extensive, site-wide SA investigation effort to identify the source and pathway for coal tar NAPL
observed in the Poudre River.
5.2.1 River Channel Investigation Site Preparation
River diversion and dewatering of the river channel were selected by Xcel Energy as the preferred method
for access to the river during the investigation. This would allow easy access for drilling, a relatively
water-free investigation area within the river channel during trenching, removal of contaminated in-
stream sediments, and for reconstruction of the channel and banks. Stream diversion and dewatering also
served to reduce sediments generated during construction of the channel and enabled excavation in an
environment relatively free of water.
Temporary earthen dams were constructed above and below the investigation area with a high-density
polyethylene liner to divert flow from the area of excavation and reconstruction. A pump station with
two, 12-inch pumps was set up to divert upstream flow 200 feet downstream of the excavation and
reconstruction area (Figure 14). A temporary water treatment station, sediment stockpile, and dewatering
pad were constructed to contain all investigation-derived wastes generated during river diversion and
excavation.
5.2.2 River Channel Investigation Drilling Program
RETEC developed and implemented a bedrock investigation that included the use of HSA borings to
evaluate the extent of coal tar within the riverbed; however, 20 additional borings were added during the
investigation to investigate upland areas adjacent to the river and potential sources on the opposite
(northeast) bank of the river (Figure 14). Soil borings were advanced using an HSA drill rig with 4.25-
inch diameter auger flights equipped with a split-spoon sampling barrel. All borings where contamination
was encountered were advanced to a depth of 10 feet past the last observed contamination, except for
PRBB-16 and PRBB-21, which reached refusal before this depth could be achieved.
At borehole locations where pooled NAPL was encountered at the bedrock surface (PRSB-2, 3, 4, 8, 9,
and PRBB-5), the 4.25-inch auger flights were pulled from the boring and larger diameter auger flights
(10.25-inches in diameter) were advanced approximately 1 foot into bedrock using the same borehole.
The augers were then retracted, and approximately 2 bags of granular bentonite were poured through the
auger flights and hydrated, creating a plug to prevent the down-hole migration of contaminated fluids.
The larger-diameter flights were left in place, acting as a temporary surface casing, and the 4.25-inch
auger was advanced through them to the total depth of the boring. This procedure was followed wherever
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coal tar NAPL was encountered at the alluvium/bedrock interface, except for location PRSB-1, where the
borehole was advanced to depth with the 4.25-inch augers only.
Coal tar impacts were observed in the alluvium and within several distinct intervals of bedrock fractures
and bedding planes in three borings in the river channel itself (PRSB-01, 02, and 09). In borings PRSB-
08, 03, and 04, coal tar impacts were observed only within several distinct intervals of bedrock in
individual fractures and bedding planes.
On the northeast riverbank, coal tar sheen and staining were observed in bedrock at 23 feet bgs within
several bedding planes. A faint petroleum odor was also observed at 26.5 feet bgs in boring PRBB-16.
Coal tar impacts were not observed in borings PRBB-14, 15, and 23 (Figure 14).
Nine borings were advanced along the southwest riverbank. Borings PRBB-10, 12, 6, 7, and 21 all
showed coal tar impacts only within several distinct intervals of bedrock fractures and bedding planes.
Borings PRBB-11 and PRBB-13, which are located along the riverbank at the south end of the site,
showed no coal tar impacts of any kind. Coal tar impacts were not observed in borings PRBB-22, 17D,
and PRBB-17S (alluvial) along the riverbank at the far north end of the site.
Three borings were advanced within the landfill area of the site. Borings PRBB-19 and PRBB-20 both
exhibited coal tar impacts only within several distinct intervals of bedrock fractures and bedding planes.
Borings PRBB-18 and PRBB-22, at the far north portion of the landfill, did not exhibit NAPL impacts of
any kind.
Permanent wells were constructed at 13 locations on both banks of the river channel (Figure 14). All 13
wells were screened within the bedrock, except for PRBB-17S, which was screened from the bedrock
alluvium interface into the alluvium and nested with monitoring well PRBB-17D to assess the vertical
hydraulic gradient near the Poudre River. Bedrock monitoring wells were screened across NAPL
impacted intervals or screened at the same depth as the nearest well locations where NAPL impacts were
observed.
Five temporary monitoring wells were constructed within the river channel bottom (PRSB-2, 3, 4, 8, and
9). Temporary wells located within the river channel and one soil boring (PRSB-1) were abandoned and
filled with granular bentonite before the river flow was restored.
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5.2.3 River Channel Investigation Trenching Program
Observation trenches were excavated in the streambed in an attempt to identify source areas and potential
pathways of coal tar NAPL to the river (Figure 14). An L-shaped observation trench (containing test pits
TP-01 and TP-02) was excavated about 5 feet perpendicular to and approximately 175 feet parallel to the
western side of the river channel in the observed seep area. A sump was constructed at the top of the L-
shaped trench (TP-01) to collect water and coal tar NAPL, and pump them to a temporary water treatment
system. In addition, 10 other trenches/test pits were excavated between the upstream and downstream
diversion dams (Figure 14). Observations for each trench included:
• Coal tar NAPL impacts
• Bedrock/alluvium interface and elevation
• Bedrock elevation and alluvial thickness
• Coal tar NAPL impact elevations
• Coal tar NAPL flow characteristics
• Physical properties of the trench
Sampling protocols established in the work plan regarding the use of ultraviolet (UV) fluorescence
technology to identify petroleum-related NAPL were waived by stakeholders during the excavation of
TP-01 and TP-02 because visual observations were sufficient to meet the goals of the work plan due to
the volume and obvious, visual nature of coal tar impacts.
Observations from trenching resulted in a better understanding of the characteristics of coal tar NAPL
within the alluvial sediments and in the bedrock underlying the river channel. In general, coal tar was
observed within the alluvial sediments from the seep area 200 feet upstream and from the western bank
40 to 50 feet across the channel to the eastern bank (Figure 14). Depth of trenching activities averaged
from about 2 to 4 feet within the river channel. Coal tar observed in bedrock was far more widespread
than in the alluvial sediments. Coal tar was observed in bedrock throughout the river channel and on the
western river bank from PRSB-4 to PRSB-8 and west into the landfill. Coal tar was observed in both
alluvial sediments and in bedrock fractures and bedding planes in test pits TP-01, 02, 10, 11, and 12.
Coal tar was observed only in bedrock fractures and bedding planes in test pits TP-03, 04, 05, 06, and 07.
Coal tar impacts were not observed in test pits TP-08 and TP-09 (Figure 14).
5.3 River Channel Investigation Conclusions
The summary conclusions from RETEC's report of the investigation (RETEC 2004) include the
following: "Physical observations and chemical data indicate contaminant (NAPL) mass is concentrated
beneath the river; Vertical and horizontal gradients fluctuate with seasonal changes in river stage and
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likely control the presence of NAPL beneath the riverbed; The bedrock drilling investigation provided
significant data to characterize the extent of NAPL at the site. However, the presence or absence of
specific upgradient sources, potential transport mechanisms, and the rate of NAPL flow, if occurring at
all, remains undefined; the question of whether the NAPL and groundwater system are in equilibrium,
remains undefined."
Tetra Tech and EPA did not concur with many of the conclusions stated in the RETEC results report.
During trenching along the bedrock surface, a continuous source of coal tar appeared to enter the trench.
This indicated the potential for an ongoing source to the Poudre River. Secondly, the observation of
product in fractures beneath the surface of the Pierre Shale bedrock suggested an explanation as to why
there appeared to be little or no dissolved phase contamination associated with the coal tar NAPL plume
in the overlying alluvial aquifer. The presence of coal tar in bedrock below the alluvium/bedrock
interface was confirmed by borings placed by RETEC adjacent to the river on the upland (western) bank.
Coal tar NAPL was discovered beneath the bedrock surface to a depth of nearly 10 feet below the alluvial
contact. In EPA's opinion, this suggested that the previously unidentified bedrock fractures could be a
pathway for coal tar migration to the river from upland sources, such as the former MGP. This pathway
could provide an ongoing source to the river that had not been detected during previous investigations that
focused on the overlying alluvium. However, because of the inconclusive nature of the findings reported
by RETEC, EPA continued to pursue the development of an SA work plan to address data gaps and
further refine the teams understanding of the potential flow path between the river and the MGP source
area.
5.4 Evaluation Of Fugitive Emissions Using Ground-Based Optical Remote Sensing
Technology
A study was conducted in September 2003 by ARCADIS and EPA personnel (with support from the
Monitoring and Measurement Technologies for the 21st Century initiative; http://clu-
in.org/programs/21m2/openpath/op-ftir/) to evaluate emissions of fugitive gases and VOCs at the site
using an Open-Path Fourier Transform Infrared (OP-FTIR) spectrometer, Open-Path Tunable Diode
Laser Absorption, and a Ultra-Violet Differential Optical Absorption Spectrometer. The objective of this
application was to identify hot spots or emissions from the landfill to support selection of a site for the
new indoor recreation facility being planned by the City of Fort Collins. The OP-FTIR instrument
provided critical, supplemental data concerning fugitive emissions from the landfill surface. The study
involved a technique developed through research funded by EPA's National Risk Management Research
Laboratory, which used ground-based optical remote sensing technology, known as Optical Remote
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Sensing-Radial Plume Mapping (Hashmonay and Yost 1999; Hashmonay and others. 1999; Wu and
others 1999; Hashmonay and others. 2001; Hashmonay and others 2002). The effort identified emission
hot spots (areas of relatively higher emissions), investigated source homogeneity, and calculated an
emission flux rate for each compound detected at the site. Concentration maps in the horizontal and
vertical planes were generated using the Horizontal Radial Plume Mapping, and Vertical Plume Mapping
methods, respectively. For the complete report, see Evaluation of Fugitive Emissions at a Brownfield
Landfill in Fort Collins, Colorado using Ground-Based Optical Remote Sensing Technology (EPA
2004a).
A gasoline hot spot was detected to the north of the playground adjacent to the recreation center.
However, the study did not indicate the presence of any surface methane or other VOC hot spots that
could be attributed to the landfill or other potential sources at the site. For more information on the use of
OP-FTIR and this site go to http://clu-in.org/programs/21m2/openpath/op-ftir/
6.0 SITE ASSESSMENT ACTIVITIES
In October 2003, EPA issued a Technical Directive Document to Tetra Tech, under the START 2
contract, to perform an SA at the Poudre River site. Tetra Tech developed the SA for EPA Region 8 to
address observed coal tar NAPL releases to the Poudre River. The SA was conducted in cooperation
with Xcel Energy Inc., the primary PRP at the site, and with a secondary PRP, the Schrader Oil Company,
under an Administrative Order on Consent for Removal Action approved by the EPA and Schrader Oil
Company (Paragon 2004).
The project objectives and related activities described in the FSP were designed to:
1) Identify potential pathways and source area(s) for free product/NAPL identified in the Poudre
River adjacent to the site.
2) Obtain data to refine the CSM, (i.e., bedrock surface, alluvial thickness, landfill thickness,
bedrock lithology, etc).
3) Investigate whether PCE previously identified in the vicinity of the landfill was affecting the
water quality of the Poudre River.
4) Facilitate the identification of the extent and the source area(s) for gasoline/MTBE contamination
in groundwater at the site.
5) Generate data to support the design and implementation of a remedy at the site.
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6.1 Site Assessment Field Sampling Activities
This section describes the sampling and field activities conducted under the SA to accomplish the
objectives outlined in Section 1.0 of the FSP (Tetra Tech 2004b). SA field activities were conducted in
the following sequence from February through August 2004:
1) In total, 333 passive soil gas samplers were deployed from February 25 through February
28.
2) In total, 47 passive diffusion bag (PDB) samplers were installed in the western bank of
the river along the study area from March 8 through March 10.
3) In total, 329 passive soil gas samplers were retrieved and submitted for analysis from
March 22 through March 25.
4) In total, 47 PDB samplers were retrieved and sampled from March 22 through March 23.
5) A resistivity geophysical survey was conducted from March 31 through April 8.
6) Drilling, soil, and grab groundwater sampling activities began on April 19 and concluded
on July 7.
7) Groundwater levels were measured in all accessible monitoring wells and groundwater
samples were collected from 27 monitoring wells from August 2 through August 4.
6.1.1 Soil Gas Survey
Initial field sampling activities included a soil gas survey, using the EMFLUX" passive soil-gas sampling
system, in order to identify potential contaminant source areas, facilitate the delineation of groundwater
contaminant plumes, provide information on discrete contaminant pathways, and provide data on the
lateral distribution and types of contaminants present in the vadose zone. These data were also used to
guide the subsequent drilling program. Prior to implementing the soil gas survey, a DMA study was
conducted by Tetra Tech in areas previously identified as containing coal tar NAPL contamination in the
subsurface. The DMA indicated that previously identified compounds associated with coal tar at the site
could be detected using the technology, so a full-scale soil gas survey was implemented. In total, 333
passive soil-gas sampling devices were installed in a 50-foot grid across the entire site and placed every
25 feet along transects intersecting areas known and suspected to be contaminated (Figures 16 and 17).
Soil gas samplers were also placed at 20-foot intervals along transects adjacent to the upgradient
boundary of the site and along the river to locate contaminants entering the site from upgradient sources
and to locate areas where contaminants may be leaving the site and discharging into the river. The soil
gas samplers were left in place for approximately 25 days, after which they were recovered and sent to the
manufacturer for laboratory analysis. Analysis procedures are described in more depth in the Technology
Quick Reference Sheet (TQRS) in Appendix 1. Ambient air control samples, used as field blanks, were
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also collected at various locations across the site. Soil gas samplers were installed and recovered
following procedures discussed in Section 4.1 of the FSP (Tetra Tech 2004b).
The DMA indicated that several compounds associated with the presence of coal tar at the site could be
detected in soil gas and that quantitative results could be estimated using the EMFLUX model.
Compounds of interest included 1,3,5-trimethylbenzene (1,3,5-TMB), 1,2,4-trimethylbenzene
(1,2,4-TMB), and napthalene. These compounds were used to help identify locations where the presence
of coal tar NAPL in the subsurface was likely. Iso-concentration maps of target analyte distribution
across the site were generated by Kriging the data (using ordinary Kriging techniques), and Kriging was
also used to refine the CSM and optimize the field investigation drilling program. An iso-concentration
map was generated for PCE (Figure 17) due to the number of locations where PCE was detected during
the survey.
Several boring locations were chosen to investigate 'hotspots' where soil gas indicated an elevated
concentration of the target chemicals 1,3,5-TMB, 1,2,4-TMB, and/or naphthalene. The visual presence of
coal tar often correlated poorly with hotspots identified in soil gas during the survey. Several theories
could explain this apparent lack of correlation:
• Boring logs for several borings advanced in locations of soil gas hotspots identified loose, dry,
coarse material in the subsurface, which may have created a preferential pathway for soil gas in
that area causing the soil gas hotspot.
• During past investigations, the field crews have encountered and sampled isolated petroleum
based products in the landfill that appear to be unrelated to coal tar contamination from the
former MGP (Tetra Tech 2004a; Appendix 2), which may be another explanation for some of the
observed hotspots.
• The elevated concentrations of target chemicals detected beneath the parking lots relative to other
areas of known contamination across the site may result from the asphalt acting as a vapor
barrier, which would not only trap contaminant vapors and concentrate them but also cause them
to degrade more slowing by creating a reducing atmosphere.
• Chemicals might also leak from vehicles, enter cracks in the pavement, and accumulate directly
beneath the parking lots.
6.1.2 Passive Diffusion Bag Sample Results
To identify contaminant discharge locations to the river, 47 PDB samplers were installed approximately 2
feet below the depth of saturation in the riverbank along the Aztlan landfill border (Figure 17). The PDB
samples were collected and analyzed for VOCs after an equilibration period of 14 days.
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PDB samplers were also installed in three monitoring wells (FC-MW-03, FC-MW-04, and FC-MW-05)
located near the river and screened above bedrock within the alluvial zone (Figure 12). PDB samplers
were installed in these monitoring wells to assess the correlation between water sampled by the PDB
samplers in the river bank and groundwater in the alluvial aquifer to ensure that the PDB samples were
representative of groundwater discharging into the Poudre River and that they were properly placed below
the groundwater/surface water mixing zone. Figure 17 provides detected concentrations of PCE in PDB
samples placed in the riverbank.
VOC compounds detected in the PDB sampling included limited low level detections of contaminants
potentially related to primarily landfill materials, such as chlorinated solvents (PCE, trichloroethene
[TCE], 1, 2 dichloroethene, and vinyl chloride). Chlorobenzenes are commonly used as solvents, in
coolants, as a component of lubricants, as an ingredient in wood preservatives, and in the manufacture of
pesticides and herbicides (EPA 2004b). The extensive detections of chlorinated solvents in soil gas were
not considered related to the site coal tar contamination. Although chlorinated solvent contamination is
present in the landfill, it does not appear to be migrating in substantial quantities from the landfill to the
river, probably because of the high organic content of the landfill and the lack of infiltration as a result of
the presence of the landfill cap.
The types of contaminants detected and the range of concentrations correlate very well between the
monitoring well PDB samples and nearby riverbank PDB samples. Additionally, the distribution of
chlorinated solvents detected in PDB samples from the riverbank correlated well with chlorinated
solvents detected in the soil gas survey (Figure 17). Results for the PDB bags did not indicate widespread
dissolved phase contamination discharges to the river that are related to coal tar. This may be attributed
to poor recoveries of the PDB samplers for less volatile coal tar related compounds (such as naphthalene,
1,2,4-TMB, and 1,3,5-TMB) or provide further evidence that dissolved phase contaminants were not
discharging to the river in significant concentrations or quantities. The PDB samplers did, however,
assist in further identifying the widespread presence of PCE and its degradation products such as TCE,
1,2-dichloroethene, and vinyl chloride in site groundwater. The samplers further revealed that most of
these contaminants are migrating to the river in low concentrations. Of the nine different compounds
detected, PCE is the only VOC target compound that appears to be discharging to the river at
concentrations at or above the applicable maximum contaminant levels (MCL) (see Figure 17). The MCL
for PCE is 5 (ig/L.
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6.1.3 Geophysical Survey
Tetra Tech procured the services of a geophysical subcontractor, hydroGEOPHYSICS, Inc., to employ
high-resolution resistivity (HRR) and ground-penetrating radar (GPR) geophysical survey methods to
better define the bedrock surface and to identify the presence or absence of preferential pathways such as
bedrock fractures, subsurface channels in alluvium, or underground pipelines. The survey was conducted
prior to the drilling mobilization to allow time for data evaluation, CSM refinement, and subsequent
sampling strategy refinement.
The extent of the geophysical survey and transect lines are presented in Figure 18. Figure 19 provides a
graphical example of the HRR survey results with several boring locations plotted to demonstrate
agreement between bedrock elevations encountered in the field and interpretations from the HRR survey.
The HRR survey provided good characterization of subsurface conditions across the site, which correlated
well with subsurface conditions encountered during the drilling program. Soil conditions across the site
were not conducive to GPR signal penetration resulting in poor subsurface characterization using GPR. A
DMA might have shown this prior to conducting a full survey. As a result of the poor characterization by
GPR, the performance-based contract did not allow the GPR cost to be incurred.
Resistivity results were useful for determining the presence of low conductivity materials such as gravels,
highs and lows in the bedrock surface, and the depth of the landfill. These data, along with soil gas
survey results, were used to direct the intrusive soil sampling program discussed in the following section
of this report.
6.1.4 Soil Sampling
To clearly define the preferred pathway for the NAPL from the former MGP to the river, a traditional
HSA drilling program was undertaken. Traditional drilling methods were used because of the depths at
which the coal tar was expected to be observed in bedrock based on the river channel program results and
problems with refusal using direct-push technologies encountered during the TEA investigation. The
program was designed to rely heavily on the observation and description of core samples in the field
using a detailed consistent core description routine and UV light box and microscopic analyses to identify
the presence or absence of NAPL in the dark-colored Pierre Shale bedrock.
6.1.4.1 Soil Core Logging and Soil Sampling Procedures
Soil borings were advanced using an HSA drill rig and 4.25-inch diameter auger flights equipped with a
split-spoon sampling barrel. All boreholes were continuously cored to the total depth of the boring (up to
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25 feet into bedrock). The entire core was logged and lithologic descriptions prepared in accordance with
industry accepted practices and screened with a PID/FID for VOCs. Contaminant-related features such as
odor, staining, and/or unusual solid constituents such as manmade debris, were noted on the logs. The
FSP called for the visual observation of NAPL to be documented following the standardized descriptions
listed below:
• No Visible Evidence - No visible evidence of oil on soil sample
• Sheen - Any visible sheen in the water on soil particles as described by the sheen testing method
presented later in this section
• Staining - Visible brown or black staining in soil; can be visible as mottling or in bands;
typically associated with fine-grained soil
• Coating - Visible brown or black oil coating soil particles; typically associated with coarse-
grained soil such as coarse sand, gravels, and cobbles
• Oil Wetted - Visible brown or black oil wetting the soil sample; oil appears as a liquid and is not
held by soil grains (Soil oozing petroleum typically contains 2 to 3 percent petroleum.)
A UV light box was used to aid in the visual observation of petroleum-related NAPL and the description
of core samples. Using a standardized sample description method can assist in the evaluation of boring
logs to assure that the mapped extent of contamination is consistent and that NAPL characteristics are
described in a detailed manner that will provide sufficient information to support design of a remedy.
In addition to PID/FID and visual inspection, the presence of NAPL in soil cores was periodically
evaluated using a qualitative water sheen test. This water sheen test was conducted for portions of the
core where visual inspection did not indicate the presence of NAPL.
The water sheen test was performed by placing soil in a small plastic bag filled with distilled water,
shaking the bag and observing the water's surface for signs of sheen. Sheen was classified according to
the FSP as follows:
• No Sheen (NS) - No visible sheen on water surface
• Slight Sheen (SS) - Light colorless film; spotty to globular; spread is irregular, not rapid; areas of
no sheen on water surface remain; film dissipates rapidly
• Moderate Sheen (MS) - Light to heavy film; may have some color or iridescence; globular to
stringy; spread is irregular to flowing; few remaining areas of no sheen on water surface.
• Heavy Sheen (HS) - Heavy colorful film with iridescence; stringy in appearance; spread is rapid;
sheen flows off the sample; most of water surface may be covered with sheen
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To characterize the vertical extent of contamination where pooled coal tarNAPL was encountered at the
bedrock surface, the 4.25-inch auger flights were pulled from the boring and larger diameter auger flights
(e.g., 8.25-inches in diameter) were advanced to approximately 1 foot into bedrock using the same
borehole. Approximately 2 feet of granular bentonite was then poured through the auger flight and
hydrated to create a plug, preventing possible down-hole migration of contaminated fluids. The larger
diameter flights were then left in place, acting as a temporary surface casing, and the 4.25-inch auger was
advanced through them to the total depth of the boring.
The FSP called for up to 20 soil samples to be collected from soil cores where PID/FID readings were
greatest and/or where other field screening techniques indicated the presence of contamination.
6.1.4.2 Soil Sampling Results
Based on the revised CSM, the project team was able to limit the number of soil borings. In total, 11 soil
samples were collected from nine soil borings during the SA to chemically characterize the soil profile.
One coal tar product sample was collected from TTMW-07. The product sample was submitted for
analysis of physical properties only. Physical property results for the product sample were used in
conjunction with 12 additional soil and bedrock geotechnical samples collected from five borings to
support future remedial and/or removal actions.
All 11 soil samples were submitted to a fixed laboratory for analysis of VOCs by EPA SW-846 Method
8260, SVOCs by EPA SW-846 Method 8270, TPH-purgeable compounds by Iowa Method OA1 (SW-
846 Method 8015 modified), and TPH-extractable compounds by Iowa Method OA2 (SW-846 Method
8015 modified) where sufficient sample volume was available.
Results for all compounds detected in soil samples are provided in Table 6. Coal tar-related compounds
detected in the soil samples correlate well with observations of coal tar NAPL contamination and with the
approximate boundaries of coal tar impacts provided in Figure 20. Soil samples collected between the
upland area of the site in the vicinity of the Aztlan Community Center parking lot and the sand
playground area (Figure 2) contained elevated GRO compounds and DRO compounds. Chromatograms
for TPH samples at these locations indicate fresh, non-weathered fuel patterns for gasoline and diesel.
These relatively fresh fuel signatures in conjunction with multiple detections of MTBE in groundwater (a
gasoline additive used since the 1980s) reinforced the theory that more recent gasoline and diesel spills
may be mixing with historical coal tar contaminants from the former MGP in the upland areas of the site,
which was consistent with the revised preliminary CSM (Figure 13).
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Coal tar NAPL contamination in the vadose zone was observed in one soil sample. Soil sample SA-SB-
20 was collected from 9 to 10 feet bgs at location MGPMW-2D on the Schrader Oil Property (the site of
the former MGP; see Figures 2 and 20). This sample was collected from the alluvium directly above the
bedrock contact at 10 feet bgs after black, tar-like staining and strong fuel/mothball-like odors were
observed. It should be noted that the sample media was stuck in a very hot core barrel for approximately
15 minutes because the core barrel could not be immediately opened; therefore, many of the light-end,
volatile chemical constituents were probably lost before the sample could be containerized. The sample
contained highly elevated concentrations of GRO (970 milligrams per kilogram [mg/kg]), TPH (9,900
mg/kg), 1,2,4-TMB (980 micrograms per kilogram [fig/kg]), xylenes (total), 9,900 (ig/kg, dibenzofuran
(6,600 (ig/kg), and 14 target PAH compounds. The observation of coal tar NAPL contamination at this
location in both alluvium and bedrock fractures was a significant addition to the development of the CSM
considering that the sample was collected upgradient and approximately 8 vertical feet above coal tar
NAPL observed at the bedrock/alluvium contact in the Aztlan Community Center parking lot at soil
boring TTSB-02 (Figure 20). This observation provided the project team with an indication that the
source for coal tar observed on the Aztlan Community Center property was located on or very near to the
former MGP.
A potential source for PCE contamination was also revealed by the soil sample results. Sample SA-SB-
04 (from soil boring TTSB-09) was collected in the vadose zone from an organic, silty layer encountered
directly below the landfill material. PCE was detected at a concentration of 140 (ig/kg in this sample and
was the only compound detected in the VOC fraction. This sample did not contain detected
concentrations of coal tar related compounds. The PCE concentration is elevated relative to PCE
concentrations observed in other soil samples from the site and PCE groundwater concentrations at this
location (see data for SA-GW-01). This observation was interpreted by the team as a possible indication
that a source area for the observed PCE contamination was located within the landfill itself.
One coal tar product sample (TTMW-07 Product) was also collected during the SA drilling activities.
The sample was collected shortly after installation of monitoring well TTMW-07 by pumping product
from the bottom of the well using a peristaltic pump. The sample was collected and submitted for
physical analyses to assist in design of proposed remedial systems.
In total, 12 soil/bedrock samples were collected from five soil borings located near the Poudre River and
submitted for geotechnical analysis to satisfy engineering requirements for proposed remedial
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alternatives. Results of geotechnical analyses for samples collected during the SA are provided in Table
7, and in Section 4.3 of the SA FSP (Tetra Tech 2004b) in more detail.
6.1.5 Grab Groundwater Sampling
The dynamic work strategy resulted in the collection of a total of 11 grab groundwater samples collected
where soil borings were advanced without the installation of a monitoring well and visual inspection, and
results for sheen tests did not indicate the presence of NAPL. Results for grab groundwater samples
collected during the SA are provided in Table 8 and sample locations are provided on Figure 20. Grab
groundwater sample procedures are discussed in Section 4.4 of the SA FSP (Tetra Tech 2004b).
The shallow grab groundwater sample results confirmed that a significant dissolved phase plume of
petroleum-related contaminants did not extend far beyond the known boundaries of coal tar NAPL at the
site. The grab groundwater results confirmed the presence of MTBE downgradient of more recent
gasoline releases, and also confirmed the presence of PCE in groundwater near the center of the former
landfill, an area that was not sampled during the TEA.
6.1.6 Monitoring Well Sampling
Groundwater samples were collected from 11 monitoring wells installed during the SA and 16 existing
monitoring wells following procedures described in Section 4.6 of the SA FSP (Tetra Tech 2004b). The
samples were collected using micropurge groundwater sampling techniques and analyzed at an off-site
laboratory for VOCs, SVOCs, GRO, DRO, cations, and anions. See Figure 3 and Figure 20 for
monitoring well locations.
Compounds related to coal tar or NAPL at the site were detected at the greatest concentrations in
monitoring wells screened across coal tar contamination with the highest concentrations observed in
monitoring wells located near the former MGP. High concentrations of coal tar related chemicals and
other types of contamination were generally absent across most of the site. The low solubility of many of
the chemical constituents detected at the site and the relatively high estimated flow rates along the base of
the alluvial sediments is a likely explanation for the low contaminant concentration reported in
groundwater across the site.
Relatively high levels of BTEX constituents were detected in samples from monitoring wells located near
the MGP and downgradient from more recent fuel releases. This observation, along with the presence of
MTBE in monitoring wells downgradient from the Schrader Oil recorded fuel releases, provide evidence
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that gasoline and diesel spills along Willow Street are mixing with the MGP coal tar or NAPL, as
indicated in the revised preliminary CSM (Figure 14).
PCE was detected in groundwater samples from monitoring wells screened in the alluvial aquifer and the
bedrock, with the majority and highest detections coming from locations near the center of the site. This
observation provided a further indication that the source of PCE observed in groundwater was not
upgradient of the site as previously proposed, but perhaps from within the landfill as indicated by passive
soil gas results (Figure 17).
Low-level detections of 1,2 dichlorobenzene were considered more likely related to landfill materials than
coal tar contamination. Chlorobenzenes, including 1,2 dichlorobenzene, are commonly used as solvents,
in coolants, as a component of lubricants, or as an ingredient in wood preservatives, pesticides, and
herbicides (EPA 2004b).
Elevated GRO and BTEX compounds were observed in groundwater sample SA-MW-13 collected from
monitoring well PRBB-10 (Figure 10). This location is within the area of coal tar impacts within bedrock
(Figure 21). Relatively high concentrations of BTEX compounds were not observed in other groundwater
samples collected from areas of known or expected coal tar impacts near the Poudre River. It was
hypothesized that the relatively elevated concentrations of gasoline range hydrocarbons and total BTEX
could be indicative of local gasoline dumping, a spill scenario, or that another source for gasoline
contamination to groundwater was located hydrologically upgradient to the northwest of the site.
However, it is important to note that other recent investigations at the site had not detected these
compounds in groundwater samples taken from areas upgradient of this location (Tetra Tech 2004a; Tetra
Tech 2004c; RETEC 2004). The project team used BTEX ratios to provide an indication as to the age of
the potential release. An examination of the (benzene+toluene)/(ethylbenzene+xylenes) ratio (0.58) and
the benzene/toluene ratio (0.57) indicated that the gasoline contaminants in this sample were probably
less than 10 years old since ratios greater than 0.5 indicate relatively younger releases. (Air Force Center
for Environmental Excellence [AFCEE] 1999; Kaplan and Galperin 1996; Weiner 2000).
The (B+T)/(E+X) ratios observed in the upland area of the site range from 0.12 to 7.79 with and average
value of 3.0 (see Table 9). Literature values for (B+T)/(E+X) ratios in groundwater in contact with fresh
gasoline range from 1.0 to 5.0 (AFCEE 1999; Kaplan and Galperin 1996). When (B+T)/(E+X) ratios
greater than 5.0 are observed it may be an indication that the sample was not collected near the source of
the fresh gasoline NAPL since benzene and toluene tend to be more mobile than ethylbenzene and
xylenes (AFCEE 1999; Kaplan and Galperin 1996; Weiner 2000). (B+T)/(E+X) ratios of less than 0.5
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are generally observed at sites where releases are greater than 10 years old, for example at locations
MGPMW-3S and FC-MW-15 (Figures 3 and 4). The high (B+T)/(E+X) ratios observed in wells from the
Schrader property may be an indication that a more recent gasoline release has occurred in the vicinity of
these monitoring wells than the documented 1994 and 1995 releases from the Schrader Oil Bulk Plant
(COSTIS event IDs 2287 and 2223) and the 1996 Scout 66 gas station (COSTIS event ID 4273) release.
7.0 CONCLUSIONS
After the SA fieldwork was completed and all data were examined, the project team reached several
conclusions with respect to the stated objectives of the investigation.
1) The source of coal tar/NAPL contamination observed in the Poudre River appeared to be located
on or very near the former MGP site. This conclusion was based on the following observations:
a. Coal tar NAPL contamination was observed consistently between the Poudre River and
the former PVG Company site.
b. Coal tar NAPL contamination was not observed in the landfill material. Based on
coverage of soil borings across the site from the SA and previous investigations and soil
gas data, it was determined that it is unlikely that coal tar was deposited within the
landfill.
c. Coal tar NAPL contamination was observed only in alluvial material and in the top,
weathered bedrock interval from the Aztlan Community center parking lot (soil boring
FC-MW-12) to the sand playground area (soil boring TTSB-15). The greatest coal tar
NAPL thickness in alluvium was observed beneath the Aztlan Community center parking
lot in soil boring TTSB-02, which is near the former MGP site.
d. Coal tar NAPL contamination was observed only in bedrock fractures extending from the
sand playground area to near the banks of the Poudre River, in several borings advanced
within portions of the bedrock high in the southwest portion of the study area, and on the
Schrader Oil property.
e. Coal tar NAPL contamination was observed in alluvium (soil sample SA-SB-20) and in
bedrock fractures in soil boring MGPMW-2D located on the Schrader Oil property and
site of the former MGP. Coal tar NAPL contamination was not observed continuously
between the alluvium and the contaminated bedrock interval at boring MGPMW-2D,
indicating that contamination in the bedrock fractures at this location originated
upgradient or side-gradient and is not the result of vertical contaminant migration.
f Coal tar NAPL contamination that was observed on the former MGP property
(MGPMW-2D) is upgradient and approximately 8 vertical feet above coal tar NAPL
contamination observed in the Aztlan center parking lot at soil boring TTSB-02.
2) The lateral and vertical distribution of coal tar/NAPL contamination in alluvium and in bedrock
may be structurally constrained by the bedrock surface configuration and structural integrity
across the site. This conclusion was based on the following observations:
a. The bedrock surface from Willow Street adjacent to the former PVG plant to
approximately the sand playground area forms a slight valley trending
northeast/southwest (Figure 21). This valley may laterally control the spread of coal tar
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in alluvium in that area and may have directed and continue to direct coal tar in alluvium
to the northwest.
b. Competent, less fractured, sandstone and silty sandstone appears to control the vertical
migration of coal tar across the site where it occurs in the southwest and along the
northwest portions of the site (Figure22). Boring logs indicate that where the more
competent bedrock member is encountered in the upland areas of the site, and elsewhere,
no coal tar contamination is encountered in bedrock. Northwest of the sand playground
the less competent siltstone and silty sandstone bedrock member occurs and coal tar in
alluvium is not encountered but coal tar is found within bedrock fractures. It appears
that coal tar flows from upgradient source areas along the top of bedrock to the area of
the sand playground and abruptly moves down into bedrock fractures through vertical
and/or near vertical joints. From here, it appears that coal tar travels horizontally along
fracture plains until hydraulic forces bring it back to the bedrock surface in the vicinity of
the Poudre River.
c. The competent, less fractured sandstone and silty sandstone bedrock member that appears
to form a slight ridge extending northeast from the Aztlan Center parking lot (Figure 22)
may laterally control the migration of coal tar to the northwest within the bedrock
fractures. Relatively competent silty sandstone and siltstone also occur in the southeast
portions of the site that are generally more competent and less fractured, which may also
serve to laterally control coal tar migration within bedrock fractures to the southeast.
3) Coal tar may be commingled with other petroleum products in upland areas of the site. This
conclusion was based on the following observations:
a. GRO compounds, DRO compounds (identified as diesel fuel), and MTBE (in
groundwater only) have been detected at elevated concentrations in soil and groundwater
samples adjacent to Willow Street and the Aztlan Community Center parking lot.
Chromatograms for TPH samples at these locations indicate relatively fresh, non-
weathered fuel patterns for gasoline and diesel (chromatograms for samples from the
Schrader property were not reviewed). These relatively fresh fuel signatures in
conjunction with multiple detections of MTBE (a gasoline additive used since the 1980s)
indicate that more recent gasoline and diesel spills may be mixing with historic coal tar
NAPL. The relatively newer, light-end petroleum products can act as solvents for the
less mobile coal tar compounds, exacerbating the problem of coal tar migration at the
site.
b. In addition to samples from the upland area in the Aztlan Community Center parking lot,
significantly elevated GRO compounds and BTEX compounds have also been detected in
groundwater and soil samples from the Schrader property. Coal tar and other related
byproducts generated by the former MGP would be approximately 70 years old and
would typically contain relatively low BTEX constituents even when fresh and
unweathered. It is unlikely that in such an aerobic environment that these relatively
volatile, mobile, and bioavailable (especially in aerobic conditions) chemical constituents
(e.g., benzene) would remain in high concentrations after such a long period of time.
This provides further evidence that a more recent petroleum product release is
commingled with coal tar NAPL at the site.
4) An examination of (benzene + toluene)/(ethylbenzene + xylene), or (B+T)/(E+X) ratios in shallow
groundwater from the upland area of the site, and the Schrader Property wells sampled during this
SA, indicate that these contaminants originated from groundwater in contact with relatively fresh
gasoline.
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5) Multiple sources of chlorinated solvents may exist at the site. This conclusion was based on the
following observations:
a. Chlorinated solvents, primarily PCE and its degradation or 'daughter' products TCE,
1,2-dichloroethene, and vinyl chloride have been detected throughout site groundwater
and in one soil sample. In addition to numerous historical detections of these compounds
in site groundwater, seven out of 11 groundwater grab samples and 15 out of 21
monitoring well samples contained detected concentrations of PCE.
b. Most of the chlorinated solvent contamination observed in groundwater across the site is
likely originating in the former landfill. The most prevalent chlorinated solvent detected
in samples from all media at the site is PCE. PCE detected in groundwater across the site
correlates well with PCE detected in soil gas (Figures 16 and 17). Although the soil gas
survey has identified PCE in upgradient boundary areas of the site (to the west/northwest)
analyses of groundwater samples from these areas have not identified PCE contamination
(Tetra Tech 2004a; RETEC 2004) indicating that the source of PCE in soil gas from that
area is the vadose or unsaturated zone.
c. An additional, off-site source of PCE contamination may be located to the southwest of
the southern portion of the site. The soil gas survey, results for recent groundwater
samples (Tetra Tech 2004a) and the PDB samples from the riverbank all indicate a
significant source of PCE southeast of the United Way building. PCE concentrations in
groundwater samples from recent investigations (Tetra Tech 2004a) and soil gas samples
from the SA, both located along the southwestern site border, are relatively elevated
when compared to downgradient samples. The soil gas survey and results for recent
groundwater samples (Figure 13; Tetra Tech 2004a) have not identified significant PCE
concentrations downgradient of the former Giddings machine shop relative to PCE
concentrations located further downgradient at the site. This suggests that the property
located adjacent and upgradient to the site may be an additional source for PCE
contamination in groundwater. Further investigations focused on this question would be
necessary to accurately identify PCE source areas.
6) Chlorinated solvents are reaching the Poudre River in concentrations above MCLs adjacent to the
site. This conclusion was based on the following observation:
a. VOC data for the PDB samples indicate that elevated concentrations of chlorinated
solvents are reaching the Poudre River. Twenty two out of the 47 PDB samples collected
contained detected concentrations of PCE. Of these 22 detections, eight values exceeded
the MCL of 5 (ig/L. Detected concentrations of PCE in PDB samples ranged from 1 to
18 (ig/L. The highest concentrations of PCE reaching the Poudre River appear to be in
the southeast portion of the site.
7.1 Final Conceptual Site Model
The final CSM (Figure 22) provides a graphical representation of newly acquired knowledge concerning
the site including the fact that many previously installed monitoring wells and drilling programs were
adequate to assess dissolved contaminants but were not useful in locating and identifying coal tar NAPL
migration pathways in the subsurface. A review of this figure allows future project personnel to design
sampling and analysis plans that provide for the collection of data necessary to make project decisions.
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The CSM can be useful in locating potential source areas as well. The final CSM was also used in
designing the remedial alternative implemented at the site.
The chosen mitigation strategy consisted of the placement of a sheet pile wall to exclude coal tar from the
river and a French drain to remove the hydraulic head created by the sheet pile wall. Source remediation
is also being considered to further limit the potential for coal tar migration to the river.
7.2 Site Geology
Knowledge of the site geology changed significantly during the SA investigation as a result of using HSA
drilling techniques that facilitated better lithologic recovery and characterization of bedrock beneath the
site. Additional literature research was also done and incorporated after preliminary findings from the
PRP investigation indicated that bedrock fractures and bedding planes were a likely pathway for coal tar
NAPL reaching the river. The following text provides a review of the site geology based on updated
knowledge.
Native soil appears sparse within the study area with surface soil across the site consisting primarily of
silty sand and sandy silt underlain by landfill material. A continuous layer of alluvial material, identified
as Broadway alluvium, from 5 to 15 feet thick is encountered beneath the landfill and elsewhere across
the study area. Size analysis of the coarse-grained alluvium indicated that the average grain-size
distribution is 50 percent well-graded sand, 25 percent coarse gravel, and 25 percent cobbles to 12 inches.
A micaceous, humic layer of finer material containing plant remains, which is believed to be Post-Piney
Creek alluvium, was encountered intermittently across the site overlying the coarser alluvium at
thicknesses from 0.5 to 5.5 feet. During previous investigations, the site had also been identified as
overlying Post-Piney Creek Alluvium from the upper Holocene underlain by older alluvial gravel
consisting of Broadway Alluvium from the Pinedale Glaciation, Pleistocene (Tetra Tech 2004a; Shelton
and Rogers 1987). Upper Cretaceous Pierre Shale is the bedrock member underlying the site at a depth of
between 9 and 21.5 feet bgs (Figure 21).
The Pierre Shale is from 5,000 to 8,000 feet thick and locally consists of olive-gray to dark gray sandy
shale, shale, and siltstone, with a distinct local member of fine-grained sandstone and silty sandstone
(Shelton and Rogers 1987). The shale member is found in central and northeastern portions of the site. It
is typically highly weathered at the alluvium/shale contact with fractured bedding planes and joints that
decrease with depth.
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The sandstone member is typically massive with claystone and siltstone stringers and minor bedding
plane fractures and joints that decrease rapidly with depth. In areas of the site where this member was
encountered in the vadose zone it appeared highly weathered, friable and fractured at a much higher
frequency. The more competent, massive sandstone was encountered in the western, southern, and
southeastern portions of the site and appears to form a prominent high extending south from near the
center of the United Way building parking lot to the northeast between soil boring TTSB-03 and
monitoring wells PRBB-17S and PRBB-17D. A bedrock contour map was generated from soil borings
and geophysical HRR data (Figure 21).
7.3 Site Hydrology
A better understanding of site hydrology resulted from observations made during the SA investigation,
additional literature research on regional hydrology, and slug test analysis done for the alluvium and
bedrock at the site. The following text presents a review of site hydrology based on updated knowledge
incorporated from the SA investigation.
7.3.1 Surface Water
United States Geological Survey (USGS) surface water gauging Station 06752260, located approximately
1,000 feet downstream from the site near the Linden Street bridge, indicates that the 29-year mean stream
flows range from 24.8 cubic feet per second (cfs) in December to 872 cfs in June (USGS 2004). Locally,
flow rates for the Poudre River are controlled by releases from upstream reservoirs, precipitation, and
overland flow events.
A persistent seepage face along the southwest bank of the river adjacent to the site indicates that the
Poudre River is a gaining stream from the alluvial aquifer in that reach during normal and low flow
conditions. The seepage face was not observed on the southwest bank of the river when stream flows
were above 600 cfs on July 1, 2004 (USGS 2004), indicating that the flow gradient may reverse and the
river and adjacent banks may be influenced by bank storage effects during flows near or greater than 600
cfs. Furthermore, the lack of an apparent seepage face on the northeast bank of the river adjacent to the
site during normal and low flow conditions may indicate that the Poudre River is a losing stream from
that bank and that the river within that reach is a flow-through stream, which is not locally acting as a
groundwater divide for the alluvial aquifer (Dingman 1994).
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7.3.2 Hydrogeology
Groundwater generally flows in an east-northeast direction across the site. Locally there were no
identified drinking water wells or surface water intakes on or adjacent to the site. Hydrogeologic units at
the site consist of a surficial alluvial aquifer and the Pierre Shale bedrock. Shelton and Rogers (1987)
report generalized yields for alluvial materials in the study area ranging from 25 to 1,000 gallons per
minute (gpm) and for bedrock ranging from 0 to 25 gpm.
Head differences between the two hydrogeologic units suggest that the Pierre Shale locally is a semi-
confining aquifer. Past investigations conducted in the study area indicate that the Pierre Shale is a
confining aquifer (Shelton and Rogers 1987). Slug test results for the alluvial aquifer and Pierre Shale
found at the site are discussed in Section 2.5.3 of the SA report (Tetra Tech 2004d).
Depth to groundwater in the alluvial aquifer ranges from 8 to 15 feet bgs with a saturated thickness
ranging from less than 4 feet (FC-MW-12) to greater than 6 feet (BTH-15). The alluvial aquifer is
laterally confined in the southwestern portion of the site by a prominent bedrock high (Figure 21).
8.0 LESSONS LEARNED
Using the Triad approach, the amount of information available to support site decision making was
greater than what would have been available using only traditional methods. With the information gained
during the TEA and SA investigations, the City of Fort Collins and the PRPs moved forward with a reuse
plan and design/construction of mitigation strategies (see Figure 23). The original judgmental TEA
sampling plan was revised through the cooperative development of a Triad type systematic plan, which
called for the use of a dynamic work strategy for the groundwater and soil investigations, and the use of
innovative field-based technologies. Through the development and the continual refinement of the CSM,
the project team was able to clearly communicate the data gaps and discuss with stakeholders the data
needs and potential approaches. The CSM became a centralized means for discussing results and future
steps for the sampling and analysis program.
An element investigated under the SA, which had not been examined as part of previous investigations,
was the groundwater to surface water pathway that included an evaluation using a novel application of
PDB samplers placed in the riverbank adjacent to the landfill. These data provided an indication of
dissolved contaminant concentrations reaching the river via groundwater discharge zones. The presence
of PCE in the vadose zone of the landfill and the discharge of the PCE to the river was clearly defined by
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the PDB samplers; however, the PDB samplers did not appear to adequately detect the presence of less
volatile compounds, such as naphthalene.
Refinement of the site CSM indicated that dissolved plume contaminants related to coal tar NAPL do not
always approximate the location of the corresponding coal tar NAPL and contamination can extend
beyond locations where coal tar is observed (Figure 12). It is also important to note that significantly
elevated dissolved phase contamination was only detected when groundwater was sampled in zones
where coal tar NAPL was present. This may indicate that elevated dissolved phase contaminants are only
observed very near or within the coal tar NAPL plume at MGP coal tar sites. This observation may be the
rule rather than the exception for MGP coal tar sites due to the strong tendency for coal tar constituents to
cling tightly to each other; it also stresses the need for a high density of information and the need for a
very refined CSM when looking for targets that could be narrowly distributed with only a very restricted
dissolved phase plume to act as a signature around high levels of contamination.
Direct-push grab groundwater sampling methods met with limited success due to high-rates of refusal
experienced in the field. This was also impacted by the fact that coal tar NAPL contamination was deeper
than expected in many areas, including well within the bedrock. Had the site been more conducive to
direct-push grab groundwater sampling methods, this approach could have yielded the type of information
needed to delineate the coal tar NAPL plume more efficiently and cost-effectively; however, in many
cases traditional methods may need to be used in combination with innovative sampling methods to
improve data density. Tools such as the Waterloo profiler, for example, could have been used at the site
instead of direct-push retractable screen methods, allowing better characterization of groundwater during
the TEA. For information on other direct-push technologies available see the EPA's Field Analytical
Technologies Encyclopedia website at: http://fate.clu-in.org/.
Geophysical methods provided a relatively inexpensive approach for addressing the project team's
presumptions about the distribution of geologic features, such as preferred pathways at the site and
allowed the development of a more accurate CSM.
Soil gas methods and PDB samplers were demonstrated to be important alternative characterization
methods for evaluating volatile organic contamination in landfills without needing to directly penetrate
the landfills. The passive soil gas method employed at this site did not however, appear to adequately
detect the presence of the target SVOCs, such as naphthalene.
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Laboratory methods and field-based methods must be well constrained and both types of data reviewed
carefully before decision support is deemed adequate or sufficiently representative for making site
decisions. The DMA studies used at the site showed the strengths and weaknesses of the technologies
used well before full-scale programs were implemented in the field. One exception was the application of
GPR, which was not tested in the field prior to conducting the survey. This resulted in data that were not
of use to the project team; however, the cost of the survey was not passed on to the EPA due to the
performance based contracting used for the geophysical vendor. If the vendor had been able to do a
DMA for this technology, they may have avoided the unnecessary time and expense of running a GPR
survey that resulted in inadequate data and loss of payment.
For the TEA and SA investigations, the project team and the stakeholders worked as a cooperative and
efficient group to support the implementation of data collection efforts. This was primarily facilitated by
making the maximum use of existing data to construct a CSM early in the project. Other consultants had
conducted field sampling at the site for many years based on objectives which were not the same as those
used during the investigations described in this case study. By clearly redefining the project objectives
and tying them to data collection activities based on the evolving CSM, the project team and stakeholders
where able to compress the investigative process (Figure 23) and complete implementation of mitigation
efforts in as few mobilizations as possible.
9.0 COST COMPARISON
The TEA and SA at the site were conducted using principles consistent with the Triad approach and
produced considerable savings when compared with more traditional characterization and remedial design
approaches. The River Channel Investigation conducted by the PRP provided some valuable site
information but is not considered part of the site characterization activities completed under the Triad
approach. Due to the fact that costs were never fully developed for a site characterization or remedial
design based solely on a "traditional" approach it is difficult to assess cost savings for the site using a
traditional phased approach versus the Triad approach. However, the use of systematic planning, a
dynamic work plan, and field-based measurement technologies with limited off-site comparative analysis,
allowed for a cost-effective site characterization with savings estimated at 30 percent over traditional
methods. Table 10 provides a cost breakdown for site activities conducted under the Triad versus costs
assumed for a more traditional approach.
The Poudre River site was fully characterized in two mobilizations while still providing a significantly
increased quantity of data to satisfy project goals and move the site to the remedial phase. Much of the
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information collected was also used for developing and optimizing a remedial design, providing further
cost and time savings. Estimation of project costs for the work plan originally identified for the site was
difficult because the plan was changed to incorporate a more dynamic, field-based strategy before cost
scenarios had been fully calculated. Where possible, existing costs developed for the initial approach
have been used to assist in this cost comparison.
The cost comparison provided in Table 10 assumes that a traditional approach would have required at
least four mobilizations to fully evaluate the nature and extent of contamination at the property. The costs
associated with these mobilizations would have also been accompanied by costs for developing four
different work plans and accompanying sets of fixed laboratory analytical suites. In general, planning and
field preparation costs (including the DMA) under the Triad approach are higher, however additional
mobilizations and data collection activities are minimized. In this case, the higher data density and
completeness of the resulting data set eliminated the need for a third mobilization to address additional
data gaps. The use of a dynamic approach to field activities provided total site coverage using spatial
grids and allowed the field team to respond to areas with samples containing elevated levels of
contaminants. Under a more traditional plan, areas of contamination may have been missed, and any that
were encountered may not have been identified until after all the analytical data had been received and
reported to project decision makers.
The dynamic work strategy and the use of field-based measurement technologies, a geophysical survey,
and a mobile laboratory for the analysis of VOCs allowed rapid identification of areas of contamination
and real-time decision making to evaluate and help delineate the nature and extent of the contamination.
The real-time data provided flexibility to the field program that targeted areas of interest and provided
analytical cost savings. The use of field-based measurement technologies also resulted in collection of
the data necessary to choose collaborative and comparative samples that provided the best coverage of
spatial variability and ranges of contaminant concentrations. Due to resource constraints, a limited
number of samples were collected for comparative and collaborative analyses at a fixed laboratory, so it
was important to use field-based results to assist in choosing those samples for off-site analysis that
provided the best information given the budget for the site.
Use of the Triad approach at the Poudre River site allowed the property to move quickly from
investigation and characterization to construction of a remediation system in less than 2 years. With little
agreement among stakeholders as to the best approach for site funding, remediation, and closure, previous
sampling events and attempts at characterization did not provide the information necessary to identify
contaminant source areas and pathways, and implement a remedy. The cost savings are estimated at
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$163,350 or 30 percent (Table 10) using the Triad approach despite additional meetings, consultations,
and planning activities that were held between EPA Region 8, the BTSC, and the project team.
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10.0 BIBLIOGRAPHY
AFCEE 1999
Dingman 1994
EPA 2000
EPA 2004a
EPA 2004b
Air Force Center for Environmental Excellence (AFCEE). 1999. Light
Nonaqueous-Phase Weathering at Various Fuel Release Sites, Final.
Technology Transfer Division, Brooks Air Force Base, San Antonio, TX.
September.
Dingman, S. Lawrence. 1994. Physical Hydrology. Prentice-Hall, Inc.,
Upper Saddle River, New Jersey 07458.
U.S. Environmental Protection Agency (EPA). Guidance for Data
Quality Assessment. Practical Methods for Data Analysis. EPA
QA/G-9.
EPA. Evaluation of Fugitive Emissions at a Brownfield Landfill in Fort
Collins, Colorado using Ground-Based Optical Remote Sensing
Technology, Draft Final Report. Prepared by ARC ADI S. June 16.
EPA 2004. Envirofacts Master Chemical Indicator (EMCI) website.
http://www.epa.gov/enviro/html/emci/chemref/. Accessed October 5,
2004.
Hashmonay and Yost 1999
Hashmonay and others 1999.
Hashmonay and others 2001
Hashmonay and others 2002.
Kaplan and Galperin 1996
Paragon 2004
Hashmonay, R.A., and M.G. Yost 1999. Innovative Approach for
Estimating Fugitive Gaseous Fluxes using Computed Tomography and
Remote Optical Sensing Techniques. J. Air Waste Management Assoc,
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Hashmonay, R.A., M.G. Yost, and C. Wu. Computed Tomography of
Air Pollutants Using Radial Scanning Path-Integrated Optical Remote
Sensing. Atmos. Environ., 33, 267-274.
Hashmonay, R.A., D.F. Natschke, K. Wagoner, D.B. Harris, E.L.
Thompson, and M.G. Yost. Field Evaluation of a Method for Estimating
Gaseous Fluxes from Area Sources using Open-Path Fourier Transform
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Hashmonay, R.A., K. Wagoner, D.F. Natschke,D.B. Harris, and E.L.
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Annual Conference and Exhibition, Baltimore, MD.
Kaplan, I.R. and Y, Galperin. 1996. How to Recognize a Hydrocarbon
Fuel in the Environment and Estimate Its Age of Release. In
Groundwater and Soil Contamination: Technical Preparation and
Litigation Management.
Paragon Consulting Group, Inc. 2004. Final Report. EPA Requested
Assessment, Former Manufactured Gas Plant/Poudre River Site, North
College Avenue and Willow Street, Fort Collins, Colorado. CERCLA
Docket Number 08-2004-0014. October 6.
59
-------
RETEC 2004
RETEC Group, Inc. 2004. Draft, Completion Report, Non-Aqueous
Phase Source Investigation, Aztlan Center, Fort Collins, Colorado.
Prepared for Public Service Company of Colorado d/b/aXcel Energy,
Inc. June 3.
Shelton and Rogers 1987
Stewart 1996
Tetra Tech 2003
Tetra Tech 2004a
Tetra Tech 2004b
Tetra Tech 2004c
Tetra Tech 2004d
UOS 2003
USGS 2004
Walsh 200la
Walsh 200 Ib
Shelton, D. C. and Rogers, W.P. 1987. Environmental and Engineering
Geology of the Windsor Study Area, Larimer and Weld Counties,
Colorado. Colorado Department of Natural Resources, Denver,
Colorado.
Stewart Environmental Consultants, Inc. (Stewart). 1996. Voluntary
Cleanup and Redevelopment Act Application for the Fort Collins
Railroad Realignment Project Located Near Willow Street and College
Avenue, Fort Collins, Colorado. April 9, 1996.
Tetra Tech EM Inc. 2003. Final Field Sampling Plan for a Targeted
Brownfields Assessment at the Northside Aztlan Center, Fort Collins,
Larimer County, Colorado.
Tetra Tech EM Inc. 2004. Targeted Brownfields Assessment, Fort
Collins Aztlan Center, Fort Collins, Larimer County, Colorado. Field
Activities Report. February 2004.
Tetra Tech. 2004. Poudre River Removal Site Assessment, Field
Sampling Plan. Prepared for the EPA, Region 8. March.
Tetra Tech. 2004. After Action Report, Non-Aqueous Phase Source
Investigation, Poudre River Site, Fort Collins, Larimer County,
Colorado. Prepared for the EPA, Region 8. Septembers.
Tetra Tech. 2004. Poudre River Removal Site Assessment, Draft
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United States Geological Survey (USGS). Water data for USGS
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http://nwis.waterdata.usgs.gov/co/nwis/nwisman/?site_no=06752260&ag
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Walsh Environmental Scientists and Engineers, LLC (Walsh). 200la.
Phase I Environmental Site Assessment, Fort Collins Downtown River
Corridor, Fort Collins, Colorado. Prepared for the City of Fort Collins,
Downtown River Corridor Brownfields Pilot Assessment, EPA
Cooperative Agreement, Assistance ID No. BP-988300001-0. July 11,
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Walsh Environmental Scientists and Engineers, LLC (Walsh). 200Ib.
Investigation of Soil and Ground Water Contamination Downgradient of
the former Poudre Valley Gas Plant, Fort Collins, Colorado. Prepared for
60
-------
Walsh 200 Ic
Walsh 200Id
Walsh 200 le
Walsh 2002a
Walsh 2002b
Walsh 2003
Western 1996
Weiner 2000
the City of Fort Collins, Downtown River Corridor Brownfields Pilot
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988300001-0. July 15, 2001.
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Supplemental Investigation of Soil and Ground Water Contamination
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Environ., 33, 4709-4716.
62
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TABLES
-------
TABLE 1
INTERESTED PARTIES
POUDRE RIVER SITE
Interested Party
EPA Region 8
City of Fort
Collins
Xcel Energy
Schrader Oil
Company
Role
Lead agency/Regulator
Owner of Northside Aztlan Center
and Park area
Former owner of the MGP
property/PRP
Current owner of the MGP
property/PRP
Consultant
TetraTech EM Inc.
Walsh Environmental Scientists
and Engineers, LLC.
The RETEC Group, Inc.
Paragon Consulting Group, Inc.
Notes:
EPA
MGP
PRP
U.S. Environmental Protection Agency
Manufactured gas plant
Potentially responsible party
-------
TABLE 2
VOLATILE ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING TEA
POUDRE RIVER SITE
Sample Name
BTH-01
BTH-02
BTH-04
BTH-05(D)
BTH-06
BTH-08
BTH-09
BTH-10
Sample
Type
MW
MW
MW
QC
MW
MW
MW
MW
Sample
Date
7/21/03
7/22/03
7/18/03
7/18/03
7/18/03
7/17/03
7/18/03
7/17/03
Matrix
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Depth (feet below
ground surface)
Top
12.6
14.6
13
16.5
15
16.8
18
14.6
Bottom
12.6
14.6
13
16.5
15
16.8
18
14.6
Analyte
Benzene
M,P-Xylene
o-Xylene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
Naphthalene
Bromofluorobenzene
Difluorobenzene
o-Xylene
Benzene
cis-1 ,2-Dichloroethene
Ethylbenzene
m,p-Xylene
Naphthalene
Trichloroethene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
Isopropylbenzene
n-Propylbenzene
p-lsopropyltoluene
Bromofluorobenzene
Difluorobenzene
Methyl tert-butyl ether
Benzene
Bromofluorobenzene
Difluorobenzene
Bromofluorobenzene
Difluorobenzene
Naphthalene
o-Xylene
Toluene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
Isopropylbenzene
n-Propylbenzene
p-lsopropyltoluene
Methyl tert-butyl ether
Benzene
Ethylbenzene
m,p-Xylene
Bromofluorobenzene
Difluorobenzene
Bromofluorobenzene
Difluorobenzene
Bromofluorobenzene
Difluorobenzene
Tetrachloroethene
Trichloroethene
Bromofluorobenzene
Difluorobenzene
Tetrachloroethene
Bromofluorobenzene
Difluorobenzene
Sample
Concentration
(ufl/L)
490
17.3
30.1
18.3
4.4
370
73
56
160
29.6
7.06
41.5
174
6500
14.4
160
44
15.3
8.53
5.45
98
50
25
46
73
52
76
44
170
58.0
6.7
49.9
7.76
14.5
7.95
2.28
5.46
374
70
6.08
93
56
77
46
76
43
16.4
1.71
77
44
42.1
76
44
Laboratory
Qualifier
J
J
J
J
J
J
J
J
J
J
Page 1 of 6
-------
TABLE 2
VOLATILE ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING TEA
POUDRE RIVER SITE
Sample Name
BTH-11
BTH-13
FC-GW-02
FC-GW-02
FC-GW-02
FC-GW-02
FC-GW-03
FC-GW-03
FC-GW-04
FC-GW-04
FC-GW-05
FC-GW-05
FC-GW-05
FC-GW-07
FC-GW-08
FC-GW-09
FC-GW-1 1
FC-GW-12
FC-GW-1 3
Sample
Type
MW
MW
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
Sample
Date
7/16/03
7/18/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/23/03
7/23/03
7/23/03
7/23/03
7/23/03
7/23/03
7/23/03
7/23/03
7/23/03
Matrix
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Depth (feet below
ground surface)
Top
17.1
14.6
14
15
16
17
14
17
17
18
16
17
18
13
13
10
12
12
11
Bottom
17.1
14.6
14
15
16
17
14
17
17
18
16
17
18
13
13
10
12
12
11
Analyte
Tetrachloroethene
Trichloroethene
Bromofluorobenzene
Difluorobenzene
M,P-Xylene
Naphthalene
o-Xylene
Tetrachloroethene
Toluene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
Methyl tert-butyl ether
Isopropylbenzene
Benzene
Ethylbenzene
Bromofluorobenzene
Difluorobenzene
Tetrachloroethene
Toluene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
Tetrachloroethene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
Trichloroethene
Naphthalene
Tetrachloroethene
Chloroform
cis-1 ,2-Dichloroethene
Trichloroethene
Methyl tert-butyl ether
Tetrachloroethene
Trichloroethene
Naphthalene
Tetrachloroethene
Tetrachloroethene
Tetrachloroethene
cis-1 ,2-Dichloroethene
2-Hexanone
Tetrachloroethene
Sample
Concentration
(ufl/L)
6.31
10.5
76
44
5.9
151
10.3
5
1.56
13.8
3.38
6.14
2.78
4.49
1.91
79
45
1.77
1.59
2.47
1.88
2.31
1.78
2.34
1.61
3.74
2.92
5.94
3.83
8.39
2.88
9.36
3.27
7.18
2.22
9.27
2.81
70.7
4.63
1.67
3.01
8
2.67
3.89
7.19
28.0
5.32
15.6
22.5
2.96
4.4
29.9
Laboratory
Qualifier
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
Page 2 of 6
-------
TABLE 2
VOLATILE ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING TEA
POUDRE RIVER SITE
Sample Name
FC-GW-14
FC-GW-15
FC-GW-15
FC-GW-16
FC-GW-16
FC-GW-17
FC-GW-18
FC-GW-19
FC-GW-19
FC-GW-20
FC-GW-21
FC-GW-22
FC-GW-33
FC-GW-33
FC-GW-34
Sample
Type
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
Sample
Date
7/23/03
7/24/03
7/24/03
7/25/03
7/25/03
7/25/03
7/25/03
7/25/03
7/25/03
7/25/03
7/25/03
7/26/03
7/27/03
7/27/03
7/27/03
Matrix
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Depth (feet below
ground surface)
Top
11
11
17
11
15
12
12
12
15
12
15
15
13
18
13
Bottom
11
11
17
11
15
12
12
12
15
12
15
15
13
18
13
Analyte
Methyl tert-butyl ether
cis-1 ,2-Dichloroethene
Tetrachloroethene
Trichloroethene
cis-1 ,2-Dichloroethene
Tetrachloroethene
Butylbenzene
cis-1 ,2-Dichloroethene
Naphthalene
Tetrachloroethene
tert-Butylbenzene
Trichloroethene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
Bromofluorobenzene
Difluorobenzene
cis-1 ,2-Dichloroethene
Tetrachloroethene
cis-1 ,2-Dichloroethene
Tetrachloroethene
cis-1 ,2-Dichloroethene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
cis-1 ,2-Dichloroethene
Tetrachloroethene
Chloroform
Tetrachloroethene
Tetrachloroethene
Methyl tert-butyl ether
Benzene
Tetrachloroethene
1 ,2,4-Trimethylbenzene
cis-1 ,2-Dichloroethene
Tetrachloroethene
Methyl tert-butyl ether
Benzene
Ethylbenzene
m,p-Xylene
Naphthalene
o-Xylene
Toluene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
Benzene
m,p-Xylene
Naphthalene
o-Xylene
Toluene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
Isopropylbenzene
p-lsopropyltoluene
Naphthalene
Sample
Concentration
(ufl/L)
1.97
5.15
11.9
3.76
4.05
16.4
1.79
4.27
51
17.7
1.85
11.6
14.3
6.17
74
48
2.83
32.2
1.77
34.9
3.79
21.1
2.19
23.4
8.55
13.6
2.08
38.4
30.8
1.95
6
3.48
2.98
2.18
14.5
20.5
85.6
104
152
2990
149
28.5
94.8
25.3
360
54.6
6880
118
18
207
45.1
21.4
18.1
14.0
Laboratory
Qualifier
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
JD
JD
JD
JD
JD
JD
JD
JD
JD
JD
JD
JD
JD
JD
J
Page 3 of 6
-------
TABLE 2
VOLATILE ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING TEA
POUDRE RIVER SITE
Sample Name
FC-GW-34
FC-GW-35
FC-GW-36
FC-MW-03
FC-MW-04
FC-MW-05
FC-MW-07
FC-MW-08
FC-MW-09
FC-MW-10
Sample
Type
GP
GP
GP
MW
MW
MW
MW
MW
MW
MW
Sample
Date
7/27/03
7/26/03
7/26/03
10/3/03
10/3/03
1 0/3/03
10/6/03
1 0/7/03
10/6/03
1 0/7/03
Matrix
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Depth (feet below
ground surface)
Top
16
17.5
13
17.3
16.5
15.5
13.6
14
17.5
17.5
Bottom
16
17.5
13
17.3
16.5
15.5
13.6
14
17.5
17.5
Analyte
Methyl tert-butyl ether
Benzene
Naphthalene
Naphthalene
Trichloroethene
Acetone
Chloromethane
1 ,3-Dichlorobenzene
1 ,4-Dichlorobenzene
Methylene Chloride
Tetrachloroethene
Trichloroethene
1 ,3,5-Trimethylbenzene
Methyl tert-butyl ether
Chloroform
cis-1 ,2-Dichloroethene
Methylene Chloride
Tetrachloroethene
Trichloroethene
trans-1 ,2-Dichloroethene
1 ,3,5-Trimethylbenzene
Methyl tert-butyl ether
Acetone
Chloroform
cis-1 ,2-Dichloroethene
Methylene Chloride
Tetrachloroethene
Trichloroethene
1 ,3,5-Trimethylbenzene
Methyl Acetate
Chloroform
cis-1 ,2-Dichloroethene
Trichloroethene
Tetrachloroethene
1 ,3,5-Trimethylbenzene
Chloromethane
cis-1 ,2-Dichloroethene
Methylene Chloride
Tetrachloroethene
Trichloroethene
Vinyl Chloride
Acetone
Chloroform
cis-1 ,2-Dichloroethene
Ethylbenzene
Tetrachloroethene
Trichloroethene
1 ,3,5-Trimethylbenzene
Carbon Disulfide
Chloroform
Chloromethane
Methylene Chloride
Tetrachloroethene
Sample
Concentration
(ufl/L)
83.9
4.66
10.7
10.2
5.25
6.1
0.24
0.15
0.16
0.48
1.4
1
0.67
0.22
2.7
0.62
7
7.9
0.35
3
7.9
0.36
0.43
0.63
7.3
2.6
3.6
0.86
0.97
0.98
25
0.5
4.7
0.53
12
1.8
0.23
5.5
0.49
0.28
0.5
7.7
0.48
0.35
0.3
0.58
0.34
0.69
Laboratory
Qualifier
J
J
J
J
J
J
J
J
J
J
B
J
J
J
J
B
J
D
J
JB
J
J
J
J
J
J
J
B
J
Page 4 of 6
-------
TABLE 2
VOLATILE ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING TEA
POUDRE RIVER SITE
Sample Name
FC-MW-1 1
FC-MW-12
FC-MW-1 5
FC-TW-01
FC-TW-02
FC-TW-06
FC-TW-13
FC-TW-14
Sample
Type
MW
MW
MW
TW
TW
TW
TW
TW
Sample
Date
10/7/03
1 0/6/03
10/7/03
10/1/03
10/1/03
9/30/03
9/30/03
9/30/03
Matrix
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Depth (feet below
ground surface)
Top
14.4
17.2
16
13.5
21
17
18
17.5
Bottom
14.4
17.2
16
13.5
21
17
18
17.5
Analyte
Methyl tert-butyl ether
Methylcyclohexane
Acetone
Benzene
Toluene
Cyclohexane
Isopropylbenzene
Methylcyclohexane
Methyl tert-butyl ether
Acetone
Benzene
Ethylbenzene
Toluene
Cyclohexane
Isopropylbenzene
Methyl tert-butyl ether
Methylcyclohexane
Acetone
Benzene
Carbon Disulfide
Chloromethane
Styrene
Toluene
Cyclohexane
Isopropylbenzene
Ethylbenzene
Methylene Chloride
1 ,3,5-Trimethylbenzene
Ethylbenzene
Methylene Chloride
Tetrachloroethene
Trichloroethene
1 ,3,5-Trimethylbenzene
Isopropanol
Chloroform
Chloromethane
cis-1 ,2-Dichloroethene
Ethylbenzene
Methylene Chloride
Tetrachloroethene
Trichloroethene
1 ,2,4-Trimethylbenzene
Isopropanol
Ethylbenzene
Methylene Chloride
1 ,2,4-Trimethylbenzene
Isopropanol
Ethylbenzene
Methylene Chloride
1 ,2,4-Trimethylbenzene
Sample
Concentration
(ufl/L)
0.48
0.23
11
530
11
0.21
6
0.28
30
12
54
8.2
1.6
0.26
6.9
0.74
0.52
8.6
110
0.93
0.54
9.4
24
0.28
8.6
0.5
0.5
0.5
0.5
0.58
0.49
0.37
0.5
2.4
0.5
1
31
1.9
0.5
0.81
0.5
0.74
Laboratory
Qualifier
J
J
D
J
J
D
D
J
D
B
J
JB
J
JB
J
J
J
JB
B
D
B
B
Page 5 of 6
-------
TABLE 2
VOLATILE ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING TEA
POUDRE RIVER SITE
Sample Name
FC-WW-01
MW-09
SW-1
SW-2
SW-3
MW-11
MW-02
Sample
Type
IDW
MW
SL
SL
SL
MW
MW
Sample
Date
1 0/8/03
7/22/03
9/23/03
9/23/03
9/23/03
7/21/03
9/30/03
Matrix
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Depth (feet below
ground surface)
Top
13.3
0
0
0
16.2
11
Bottom
13.3
0
0
0
16.2
11
Analyte
Xylenes (total)
Acetone
Benzene
Chloromethane
Ethylbenzene
Methylene Chloride
Bromofluorobenzene
Difluorobenzene
Isopropanol
Acetone
Ethylbenzene
Methylene Chloride
1 ,2,4-Trimethylbenzene
Isopropanol
Acetone
Ethylbenzene
1 ,2,4-Trimethylbenzene
Isopropanol
Acetone
Ethylbenzene
1 ,2,4-Trimethylbenzene
Methyl tert-butyl ether
Toluene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
Isopropylbenzene
n-Propylbenzene
o-Xylene
Benzene
Ethylbenzene
m,p-Xylene
Naphthalene
Bromofluorobenzene
Difluorobenzene
Isopropanol
Xylenes (total)
Benzene
Methylene Chloride
1 ,2,4-Trimethylbenzene
Sample
Concentration
(ufl/L)
4.1
42
5.2
2.5
1.3
3.5
75
49
5.6
0.5
0.13
3.7
0.5
6.4
0.5
6.78
118
50.3
10.1
4.08
2.14
78.3
760
78.5
102
1800
78
60
150
240
20
130
Laboratory
Qualifier
JB
J
J
J
J
J
J
J
JD
D
D
JOB
JND
Notes:
B The compound was also detected in blank sample.
D The result was reported from a sample dilution.
GP Geoprobe
IDW Investigation-derived waste
The analyte was positively identified; the associated numerical value is the approximate concentration of the
analyte in the sample.
i^g/L Microgram per liter
The analysis indicates the presence of an analyte for which there is presumptive evidence to make a "tentative
identification."
QC Quality control
SL Surface location
TBA Targeted Brownfields Assessment
TW Temporary well
Page 6 of 6
-------
TABLE 3
SEMIVOLATILE ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING TEA
POUDRE RIVER SITE
Sample Name
BTH-01
BTH-01
BTH-01
BTH-01
BTH-01
BTH-01
BTH-01
BTH-01
BTH-01
BTH-01
BTH-01
BTH-01
BTH-01
BTH-01
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-02
BTH-05
BTH-05
BTH-05
BTH-05
BTH-05
BTH-05
BTH-05
BTH-05
BTH-05
BTH-05
BTH-08
BTH-13
BTH-13
BTH-13
BTH-13
BTH-13
BTH-13
BTH-13
FC-GW-15
FC-GW-15
FC-GW-15
FC-GW-15
FC-GW-15
FC-GW-15
FC-GW-15
FC-GW-15
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
Sample
Source
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
Sample
Date
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/22/03
7/18/03
7/18/03
7/18/03
7/18/03
7/18/03
7/18/03
7/18/03
7/18/03
7/18/03
7/18/03
7/17/03
7/18/03
7/18/03
7/18/03
7/18/03
7/18/03
7/18/03
7/18/03
7/24/03
7/24/03
7/24/03
7/24/03
7/24/03
7/24/03
7/24/03
7/24/03
7/27/03
7/27/03
7/27/03
7/27/03
Sample
Matrix
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Sample Depth (feet
below TOC)
12.6
12.6
12.6
12.6
12.6
12.6
12.6
12.6
12.6
12.6
12.6
12.6
12.6
12.6
14.7
14.7
14.7
14.7
14.7
14.7
14.6
14.6
14.6
14.6
14.6
14.6
14.6
14.6
14.6
14.6
14.6
14.6
16.5
16.5
16.5
16.5
16.5
16.5
16.5
16.5
16.5
16.5
16.8
14.6
14.6
14.6
14.6
14.6
14.6
14.6
17
17
17
17
17
17
17
17
18
18
18
18
Analyte
Fluorene
2-Methylnaphthalene
Phenanthrene
Phenol
1,1'-Biphenyl
Acenaphthylene
2-Methylnaphthalene
Naphthalene
Phenanthrene
Phenol
Acenaphthene
Acenaphthylene
Carbazole
Dibenzofuran
Acenaphthene
Acenaphthylene
Fluorene
Phenanthrene
Acetophenone
1,1'-Biphenyl
Acenaphthene
Anthracene
Dibenzofuran
Fluoranthene
Fluorene
Phenanthrene
Pyrene
1,1'-Biphenyl
Acenaphthene
Acenaphthylene
2-Methylnaphthalene
Naphthalene
Acenaphthene
Acenaphthylene
Anthracene
Carbazole
Dibenzofuran
Fluorene
Naphthalene
Phenanthrene
Phenol
1,1'-Biphenyl
Acenaphthylene
Fluorene
2-Methylnaphthalene
Naphthalene
Phenanthrene
1,1'-Biphenyl
Acenaphthene
Acenaphthylene
Acenaphthylene
Anthracene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Fluorene
2-Methylnaphthalene
Phenanthrene
Pyrene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Dibenzofuran
Sample
Concentration
WL)
3
6
4
13
2
10
7
230
4
13
2
10
2
1
3
8
4
3
2
3
80
7.6
10
3.8
42
37
3.8
39
130
120
410
3500
46
38
2
4
4
13
53
11
12
19
2
5.3
21
22
3.6
5
4.3
26
1600
320
340
300
110
210
360
290
14
4.1
1.8
3.5
Laboratory
Qualifier
J
J
J
J
JD
JD
D
JD
JD
J
J
J
J
J
J
J
J
J
J
J
J
JD
JD
JD
D
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
Page 1 of 4
-------
TABLE 3
SEMIVOLATILE ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING TEA
POUDRE RIVER SITE
Sample Name
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-GW-33 (18-19.5)
FC-MW-03
FC-MW-04
FC-MW-05
FC-MW-07
FC-MW-09
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-11
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
Sample
Source
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
Sample
Date
7/27/03
7/27/03
7/27/03
7/27/03
7/27/03
7/27/03
7/27/03
7/27/03
7/27/03
7/27/03
7/27/03
10/3/03
10/3/03
10/3/03
10/6/03
10/6/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/6/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
Sample
Matrix
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Sample Depth (feet
below TOC)
18
18
18
18
18
18
18
18
18
18
18
17.3
16.5
15.5
13.6
17.5
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
14.4
17.2
17.2
17.2
17.2
17.2
17.2
17.2
17.2
17.2
17.2
17.2
17.2
17.2
17.2
17.2
17.2
16
16
16
16
16
16
16
16
16
16
Analyte
Fluoranthene
Fluorene
2-Methylnaphthalene
Phenanthrene
1,1'-Biphenyl
Acenaphthylene
Fluorene
2-Methylnaphthalene
Naphthalene
Phenanthrene
1,1'-Biphenyl
4-Nitroaniline
4-Nitroaniline
4-Nitroaniline
4-Nitroaniline
Naphthalene
4-Nitroaniline
Acenaphthene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Chrysene
Dibenzofuran
2,4-Dimethylphenol
Fluoranthene
Fluorene
Phenanthrene
Phenol
Pyrene
Acetophenone
1,1'-Biphenyl
Acenaphthylene
2-Methylnaphthalene
Naphthalene
Phenanthrene
1 -Methylnaphthalene
Acenaphthene
Anthracene
Dibenzofuran
Fluoranthene
Fluorene
4-Methylphenol
Phenanthrene
Phenol
Pyrene
1,1'-Biphenyl
1 -Methylnaphthalene
Acenaphthene
Acenaphthylene
2-Methylnaphthalene
Naphthalene
Phenanthrene
Acenaphthene
Anthracene
Dibenzofuran
2,4-Dimethylphenol
Fluoranthene
Fluorene
2-Methylphenol
4-Methylphenol
Phenanthrene
Phenol
Sample
Concentration
WL)
2.7
22
74
8.3
16
21
35
72
160
12
25
20
20
20
20
1.1
20
25
15
2.1
1.2
2.2
13
17
8.1
50
72
8.2
10
3.8
37
130
490
1800
66
680
44
6.9
7
4.8
20
3
42
2.7
5.3
29
4.4
60
120
210
1800
56
72
10
10
2.8
6.6
32
1.6
4.6
60
4.2
Laboratory
Qualifier
J
JD
D
D
D
JD
D
J
J
J
J
J
JD
D
D
JD
JN
J
J
J
JN
JD
JD
JD
D
JD
J
J
J
J
Page 2 of 4
-------
TABLE 3
SEMIVOLATILE ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING TEA
POUDRE RIVER SITE
Sample Name
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-TW-01
FC-TW-02
FC-TW-02
FC-TW-06
FC-TW-13
FC-TW-14
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
FC-WW-01
SW-1
SW-2
SW-3
MW-02
MW-02
MW-02
MW-02
MW-02
MW-02
MW-02
MW-02
MW-02
MW-02
MW-02
MW-02
MW-02
MW-02
MW-11
MW-11
Sample
Source
MW
MW
MW
MW
MW
MW
MW
MW
TW
TW
TW
TW
TW
TW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
IDW
SL
SL
SL
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
Sample
Date
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/7/03
10/1/03
10/1/03
10/1/03
9/30/03
9/30/03
9/30/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
10/8/03
9/23/03
9/23/03
9/23/03
9/30/03
9/30/03
9/30/03
9/30/03
9/30/03
9/30/03
9/30/03
9/30/03
9/30/03
9/30/03
9/30/03
9/30/03
9/30/03
9/30/03
7/21/03
7/21/03
Sample
Matrix
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Sample Depth (feet
below TOC)
16
16
16
16
16
16
16
16
13.5
21
21
17
18
17.5
0
0
0
11
11
11
11
11
11
11
11
11
11
11
11
11
11
16.2
16.2
Analyte
Pyrene
1,1'-Biphenyl
1 -Methylnaphthalene
Acenaphthene
Acenaphthylene
2-Methylnaphthalene
Naphthalene
Phenanthrene
4-Nitroaniline
4-Nitroaniline
4-Nitroaniline
4-Nitroaniline
4-Nitroaniline
4-Nitroaniline
Acenaphthene
Acenaphthylene
Anthracene
Chrysene
Dibenzofuran
2,4-Dimethylphenol
4,6-Dinitro-2-methylphenol
Fluoranthene
Fluorene
2-Methylnaphthalene
4-Methylphenol
Pentachlorophenol
Phenanthrene
Phenol
Pyrene
Acetophenone
1,1'-Biphenyl
Acenaphthene
Acenaphthylene
Dibenzofuran
2,4-Dimethylphenol
Fluoranthene
Fluorene
2-Methylnaphthalene
Naphthalene
Phenanthrene
Phenol
Pyrene
1,1'-Biphenyl
4-Nitroaniline
4-Nitroaniline
4-Nitroaniline
Acenaphthene
Anthracene
Dibenzofuran
Fluoranthene
Fluorene
2-Methylphenol
4-Methylphenol
Phenanthrene
Pyrene
1,1'-Biphenyl
Acenaphthylene
2-Methylnaphthalene
Naphthalene
4-Nitroaniline
ACENAPHTHENE
Acenaphthylene
Sample
Concentration
WL)
7.5
41
4.4
74
130
310
2500
60
20
20
100
20
20
20
14
10
1.6
1.2
1.9
11
1.8
2.8
10
51
1.3
1.6
22
2.4
4.3
1.6
4.8
15
11
2
11
3
11
55
130
24
2.9
4.6
5.1
20
20
20
5.3
7.2
5.6
2
23
3.3
15
15
3.5
6.8
88
250
1300
1000
35
67
Laboratory
Qualifier
JN
JD
JD
D
D
JD
J
J
J
J
J
J
J
J
J
J
J
D
D
JD
D
JD
D
D
D
D
JD
JD
JD
J
J
J
JD
D
D
Page 3 of 4
-------
TABLE 3
SEMIVOLATILE ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING TEA
POUDRE RIVER SITE
Sample Name
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
MW-11
Sample
Source
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
MW
Sample
Date
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
7/21/03
Sample
Matrix
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Sample Depth (feet
below TOC)
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
16.2
Analyte
Anthracene
Carbazole
Dibenzofuran
2 ,4-Dimethylphenol
Fluoranthene
Fluorene
4-Methylphenol
Phenanthrene
Phenol
Pyrene
Acetophenone
1,1'-Biphenyl
Acenaphthene
Acenaphthylene
2 ,4-Dimethylphenol
Fluorene
2-Methylnaphthalene
Naphthalene
Phenanthrene
1,1'-Biphenyl
Sample
Concentration
WL)
8
5
7
39
3
36
14
39
2
4
3
22
35
76
26
39
92
1000
39
23
Laboratory
Qualifier
J
J
J
J
J
J
J
JD
JD
JD
JD
JD
D
JD
JD
Note:
D The result was reported from a sample dilution.
GP Geoprobe
IDW Investigation-derived waste
The analyte was positively identified; the associated numerical value is the approximate concentration of the analyte in the
sample.
|ag/L Microgram per liter
MW Monitoring well
The analysis indicates the presence of an analyte for which there is presumptive evidence to make a "tentative
identification."
SL Surface location
TBA Targeted Brownfields Assessment
TOC Top of casing
TW Temporary well
Page 4 of 4
-------
TABLE 4
PAH CONCENTRATIONS IN M9/kg, CACHE LA POUDRE RIVER SAMPLES AND POTENTIAL UPGRADIENT SOURCE SAMPLES
POUDRE RIVER SITE
PAH Compound
NAPHTHALENE
ACENAPHTHYLENE
ACENAPHTHENE
FLUORENE
PHENANTHRENE
ANTHRACENE
FLUORANTHENE
PYRENE
BENZO(A)ANTHRACENE
CHRYSENE
BENZO(B)FLUORANTHENE
BENZO(K)FLUORANTHENE
BENZO(A)PYRENE
INDENO(1,2,3-CD)-PYRENE
DIBENZO(A,H)-ANTHRACENE
BENZO(G,H,I)PERYLENE
Sample
FC-PR-01
Mg/kg
270,000
110,000
32,000
72,000
150,000
49,000
55,000
49,000
19,000
20,000
6,700
12,000
14,000
7,500
1,500
6,500
Sample
FC-PR-01
Normalized to
Benzo(a)pyrene
19.29
7.86
2.29
5.14
10.71
3.50
3.93
3.50
1.36
1.43
0.48
0.86
1.00
0.54
0.11
0.46
Sample
TP-2, 11.5'
Mg/kg
1,055,000
350,000
330
184,950
335,500
120,000
124,000
139,000
46,300
330
330
330
330
330
330
330
Sample
TP-2, 11.5'
Normalized to
Benzo(a)pyrene
3,196.97
1,060.61
1.00
560.45
1,016.67
363.64
375.76
421.21
140.30
1.00
1.00
1.00
1.00
1.00
1.00
1.00
Sample
FC-PS-01
MQ/kg
13,000,000
4,300,000
1,900,000
3,600,000
8,500,000
2,400,000
2,300,000
3,100,000
1,100,000
1,300,000
440,000
530,000
820,000
1,500,000
1,500,000
1,500,000
Sample
FC-PS-01
Normalized to
Benzo(a)pyrene
15.85
5.24
2.32
4.39
10.37
2.93
2.80
3.78
1.34
1.59
0.54
0.65
1.00
1.83
1.83
1.83
Sample
H1250
Mg/kg
125
6500
10000
12000
22000
7400
8600
9900
4800
4200
4800
4200
3700
1200
150
1300
Sample
H1250
Normalized to
Benzo(a)pyrene
0.03
1.76
2.70
3.24
5.95
2.00
2.32
2.68
1.30
1.14
1.30
1.14
1.00
0.32
0.04
0.35
Sample
BTH-10(5-15')
Mg/kg
500
1,100
360
660
880
420
970
2,400
740
770
1,400
200
1,300
450
200
480
Sample
BTH-10(5-15')
Normalized to
Benzo(a)pyrene
0.38
0.85
0.28
0.51
0.68
0.32
0.75
1.85
0.57
0.59
1.08
0.15
1.00
0.35
0.15
0.37
Sample
PRSB-8DL
Mg/kg
220,000,000
31,000,000
60,000,000
52,000,000
89,000,000
28,000,000
32,000,000
31,000,000
12,000,000
13,000,000
8,500,000
6,800,000
8,500,000
8,500,000
8,500,000
8,500,000
Sample
PRSB-8DL
Normalized to
Benzo(a)pyrene
25.88
3.65
7.06
6.12
10.47
3.29
3.76
3.65
1.41
1.53
1.00
0.80
1.00
1.00
1.00
1.00
Sample
TR01SP
Mg/kg
1,100,000
290,000
180,000
280,000
490,000
150,000
180,000
170,000
66,000
69,000
27,000
40,000
47,000
60,000
60,000
60,000
Sample
TR01SP DL
Normalized to
Benzo(a)pyrene
24.67
6.40
3.93
6.13
10.67
3.27
4.00
3.73
1.47
1.53
0.59
0.87
1.00
1.37
1.37
1.37
Notes:
Values in bold print represent one half the quantitation limit for non-detected compounds.
Microgram per kilogram
Polynuclear aromatic hydrocarbon
PAH
Page 1 of 1
-------
TABLE 5
TTMW-07 COAL TAR PRODUCT SAMPLE PHYSICAL ANALYSIS RESULTS FROM SA
POUDRE RIVER SITE
Physical Method
Specific Gravity
Viscosity @ 10 degrees Celsius
Viscosity @ 20 degrees Celsius
Water Content
Surface Tension
Analytical Method
ASTMD1 475-85
ASTM D445
ASTM D445
ASTM E 203
ASTM D 1331
Result
1.02
30.65
20.32
11.79
31
Units
N/A
cSt
cSt
% water
dynes/cm
Notes:
ASTM
cSt
dynes/cm
N/A
SA
American Society for Testing and Materials
centistokes
dynes per centimeter
Not Applicable
Site Assessment
Page 1 of 1
-------
TABLE 6
ORGANIC COMPOUNDS DETECTED IN SOIL DURING SA
POUDRE RIVER SITE
Point Name
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
MGPMW-2D
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-01
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
Sample ID
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-20
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-01
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
Sample Date
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
6/29/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/19/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
Sample
Media
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
Sample
Company
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
Duplicate
ID
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Upper
Sample
Depth (ft)
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
15
15
15
15
15
15
Lower
Sample
Depth (ft)
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
15.5
15.5
15.5
15.5
15.5
15.5
Analytical
Group
VOA
VOA
VOA
VOA
VOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
VOA
VOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
VOA
VOA
VOA
VOA
VOA
VOA
Chemical Name
1 ,2,4-Trimethylbenzene
m&p-Xylene
Naphthalene
o-Xylene
Xylene (Total)
2-Methylnaphthalene
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(k)fluoranthene
Chrysene
Dibenzofuran
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Pyrene
1 ,2,4-Trimethylbenzene
Naphthalene
2-Methylnaphthalene
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
Dibenzofuran
Fluoranthene
Fluorene
lndeno(1 ,2,3-cd)pyrene
Naphthalene
Phenanthrene
Pyrene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
m&p-Xylene
Naphthalene
n-Butylbenzene
n-Propylbenzene
Laboratory
Concentration
(WJ/kg)
9800
4400
450000
5500
9900
150000
6700
35000
17000
8700
6200
5100
8900
6600
16000
35000
170000
64000
21000
360
25000
3800
2600
22000
8200
3800
2900
2700
560
1500
3800
2100
7500
15000
620
34000
36000
9700
3800
1300
480
86000
870
1100
Laboratory
Qualifier
Laboratory
Reporting
Limit
3000
3000
24000
3000
3000
20000
3900
3900
3900
3900
3900
3900
3900
3900
3900
3900
20000
20000
3900
290
2300
380
380
3800
3800
380
380
380
380
380
380
380
3800
3800
380
3800
3800
3800
280
280
280
5600
280
280
Dilution
Factor
602
602
602
602
12
12
12
12
12
12
12
12
12
12
12
12
12
5.92
5.92
57.3
229
1.14
1.14
1.14
1.14
1.14
1.14
1.14
1.14
1.14
1.14
1.14
1.14
1.14
1.14
1.14
5.72
11.4
56.2
56.2
56.2
562
56.2
56.2
Page 1 of 3
-------
TABLE 6
ORGANIC COMPOUNDS DETECTED IN SOIL DURING SA
POUDRE RIVER SITE
Point Name
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-02
TTSB-05
TTSB-05
TTSB-05
TTSB-05
TTSB-05
TTSB-05
TTSB-05
TTSB-05
TTSB-05
TTSB-05
TTSB-05
TTSB-05
TTSB-05
TTSB-05
TTSB-09
TTSB-15
TTSB-15
TTSB-15
TTSB-15
TTSB-15
TTSB-15
TTSB-15
TTSB-15
TTSB-15
TTSB-15
Sample ID
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-02
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-03
SA-SB-04
SA-SB-07
SA-SB-07
SA-SB-07
SA-SB-07
SA-SB-07
SA-SB-07
SA-SB-07
SA-SB-07
SA-SB-08
SA-SB-08
Sample Date
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/20/2004
4/22/2004
4/22/2004
4/22/2004
4/22/2004
4/22/2004
4/22/2004
4/22/2004
4/22/2004
4/22/2004
4/22/2004
4/22/2004
4/22/2004
4/22/2004
4/22/2004
4/27/2004
5/5/2004
5/5/2004
5/5/2004
5/5/2004
5/5/2004
5/5/2004
5/5/2004
5/5/2004
5/5/2004
5/5/2004
Sample
Media
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
Sample
Company
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
Duplicate
ID
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Upper
Sample
Depth (ft)
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
4
17
17
17
17
17
17
17
17
18
18
Lower
Sample
Depth (ft)
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
15.5
19
19
19
19
19
19
19
19
19
19
19
19
19
19
9
17.5
17.5
17.5
17.5
17.5
17.5
17.5
17.5
18.5
18.5
Analytical
Group
VOA
VOA
VOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
VOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
SVOA
SVOA
VOA
SVOA
Chemical Name
o-Xylene
p-lsopropyltoluene
Xylene (Total)
2-Methylnaphthalene
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
Dibenzofuran
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Pyrene
Naphthalene
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Chrysene
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Pyrene
Tetrachloroethene
1 ,2,4-Trimethylbenzene
Acetone
Naphthalene
n-Butylbenzene
o-Xylene
Xylene (Total)
Acenaphthylene
Phenanthrene
Methylene chloride
Phenanthrene
Laboratory
Concentration
(WJ/kg)
740
490
1200
7800
28000
51000
25000
17000
14000
13000
2800
7700
17000
5400
33000
33000
130000
110000
50000
5600
640
3300
1900
1500
1300
1200
400
1500
3100
1100
1100
7800
3700
140
28
42
49
13
5.8
5.8
390
550
8.1
710
Laboratory
Qualifier
J
Laboratory
Reporting
Limit
280
280
280
3700
3700
19000
3700
3700
3700
3700
3700
3700
3700
3700
3700
3700
19000
19000
19000
560
370
370
370
370
370
370
370
370
1800
370
370
1800
1800
6.0
5.6
22.
11.
5.6
5.6
5.6
360
360
5.4
360
Dilution
Factor
56.2
56.2
56.2
11.2
11.2
11.2
11.2
11.2
11.2
11.2
11.2
11.2
11.2
11.2
11.2
11.2
11.2
5.46
5.46
56
1.12
1.12
1.12
1.12
1.12
1.12
1.12
1.12
1.12
1.12
1.12
5.59
5.59
1.19
1.12
1.12
1.12
1.12
1.12
1.12
1.1
1.1
1.07
1.09
Page 2 of 3
-------
TABLE 6
ORGANIC COMPOUNDS DETECTED IN SOIL DURING SA
POUDRE RIVER SITE
Point Name
TTSB-16
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
TTSB-21
Sample ID
SA-SB-09
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
SA-SB-10
Sample Date
5/6/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
Sample
Media
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
Sample
Company
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
Duplicate
ID
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Upper
Sample
Depth (ft)
19
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Lower
Sample
Depth (ft)
19.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
21.5
Analytical
Group
VOA
VOA
VOA
VOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
Chemical Name
Methylene chloride
1 ,2,3-Trichlorobenzene
Naphthalene
Xylene (Total)
2-Methylnaphthalene
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
Dibenzofuran
Fluoranthene
Fluorene
lndeno(1 ,2,3-cd)pyrene
Naphthalene
Phenanthrene
Pyrene
Laboratory
Concentration
(WJ/kg)
10
450
400000
400
68000
4400
27000
12000
6700
4200
2800
710
3600
7000
2100
12000
20000
810
83000
50000
18000
Laboratory
Qualifier
J
J
Laboratory
Reporting
Limit
6.1
340
27000
340
8900
450
8900
8900
8900
450
450
450
450
8900
450
8900
8900
450
8900
8900
8900
Dilution
Factor
1.22
67.6
2700
67.6
1.35
1.35
1.35
1.35
1.35
1.35
1.35
1.35
1.35
1.35
1.35
1.35
1.35
27
27
27
27
Notes:
ft Feet
J The analyte was positively identified; the associated numerical value is the approximate concentration of the analyte in the sample.
(jg/kg Microgram per kilogram
NA Not applicable
SA Site Assessment
SVOA Semivolatile organic analysis
TTEMI Tetra Tech EM Inc.
VOA Volatile organic analysis
Page 3 of 3
-------
TABLE 7
SOIL AND BEDROCK GEOTECHNICAL ANALYSIS RESULTS FROM SA
POUDRE RIVER SITE
Point
Name
TTSB-22
TTSB-22
TTSB-22
TTSB-25
TTSB-26
TTSB-27
TTSB-27
TTSB-27
TTSB-27
TTSB-28
TTSB-28
TTSB-28
Sample ID
SA-SB-11
SA-SB-12
SA-SB-13
SA-SB-14
SA-SB-15
SA-SB-15B
SA-SB-16
SA-SB-16B
SA-SB-16C
SA-SB-17
SA-SB-18
SA-SB-19
Sample
Date
5/12/2004
5/12/2004
5/12/2004
5/17/2004
5/18/2004
5/19/2004
5/19/2004
5/19/2004
5/19/2004
5/19/2004
5/19/2004
5/19/2004
Sample
Company
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
Upper
Sample
Depth (ft)
9
11.5
21.5
9
10
4.5
17
17.5
16.5
9
14
19
Lower
Sample
Depth (ft)
10.5
13
22
10.5
10.5
5
17.5
18
17
10.5
15.5
20.5
Media
Landfill
Alluvium
Bedrock
Bedrock
Bedrock
Landfill
Bedrock
Bedrock
Bedrock
Landfill
Alluvium
Alluvium
Analysis
ASTM D2937, CU w/ pore pressure
ASTM D2937, direct shear
Unconfined Compressive Strength
Unconfined Compressive Strength
Unconfined Compressive Strength
ASTM D2937, direct shear
Unconfined Compressive Strength
Unconfined Compressive Strength
Unconfined Compressive Strength
ASTM D2937, direct shear
ASTM D2937, direct shear
ASTM D2937, direct shear
Moisture
(%)
NA
NA
14.3
20.1
16.5
NA
20.6
21.2
18.4
NA
NA
NA
Dry
Density
NA
NA
117
108
114
NA
104
104
110
NA
NA
NA
Unconfined
Compressive
Strength (psf)
NA
NA
23400
8000
16500
NA
NP
2900
8100
NA
NA
NA
Soil Type
Sandstone, Medium moist, olive-gray
Sandstone, Medium moist, olive
Sandstone, medium moist, olive
Sandstone/claystone, moist, dark yellow, olive brown
Weathered sandstone, medium moist, olive
Sandstone, medium moist, olive brown
Notes:
ASTM
CU
ft
NA
NP
psf
TTEMI
American Society for Testing and Materials
Consolidated-undrained
Feet
Not applicable
Not possible
Pounds per square foot
Tetra Tech EM Inc.
Page 1 of 1
-------
TABLE 8
ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING SA
POUDRE RIVER SITE
Point Name
BTH-07
BTH-07
BTH-08
BTH-08
BTH-08
BTH-09
BTH-09
BTH-09
BTH-14
BTH-14
BTH-15
BTH-15
BTH-15
FCMW03
FCMW04
FCMW04
FCMW04
FCMW04
FC-MW-04
FC-MW-04
FC-MW-04
FC-MW-04
FCMW05
FCMW05
FC-MW-05
FC-MW-05
FC-MW-05
FC-MW-05
FC-MW-05
FC-MW-05
FC-MW-05
FC-MW-09
FC-MW-09
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-12
Sample ID
SA-MW-18
SA-MW-18
SA-MW-1 1
SA-MW-1 1
SA-MW-1 1
SA-MW-04
SA-MW-04
SA-MW-04
SA-MW-1 0
SA-MW-1 0
SA-MW-06
SA-MW-06
SA-MW-06
FCMW03
FCMW04
FCMW04
FCMW04
FCMW04
SA-MW-21
SA-MW-21
SA-MW-21
SA-MW-21
FCMW05
FCMW05
SA-MW-1 9
SA-MW-1 9
SA-MW-1 999
SA-MW-1 999
SA-MW-1 999
SA-MW-1 999
SA-MW-1 999
SA-MW-1 7
SA-MW-1 7
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-07
Sample
Date
8/4/2004
8/4/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
7/7/2004
7/7/2004
7/7/2004
7/7/2004
7/7/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
7/7/2004
7/7/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
Sample
Media
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Sample
Company
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
Duplicate ID
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
SA-MW-1 999
SA-MW-1 999
SA-MW-1 9
SA-MW-1 9
SA-MW-1 9
SA-MW-1 9
SA-MW-1 9
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Sample Depth
(ft)
19
19
NA
NA
NA
19
19
19
18
18
17
17
17
19.83
18.69
18.69
18.69
18.69
17.5
17.5
17.5
17.5
18.18
18.18
17.5
17.5
17.5
17.5
17.5
17.5
17.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
18.5
Analytical
Group
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
SVGA
SVGA
Chemical Name
Methyl-tert-butyl ether
Tetrachloroethene
Methyl-tert-butyl ether
Tetrachloroethene
Trichloroethene
1 ,2-Dichlorobenzene
Chloroform
Tetrachloroethene
Tetrachloroethene
Trichloroethene
1 ,2-Dichlorobenzene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
1 ,2-Dichloroethene (Total)
cis-1 ,2-Dichloroethene
Tetrachloroethene
Trichloroethene
1 ,2-Dichloroethene (Total)
cis-1 ,2-Dichloroethene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
Trichloroethene
1 ,2,3-Trichlorobenzene
1 ,2,4-Trichlorobenzene
Hexachloro-1 ,3-butadiene
Tetrachloroethene
Trichloroethene
Chloroform
Tetrachloroethene
1 ,2,4-Trimethylbenzene
1,2-Dichloroethane
1 ,3,5-Trimethylbenzene
Benzene
Ethylbenzene
Isopropylbenzene (Cumene)
m&p-Xylene
Methyl-tert-butyl ether
Naphthalene
n-Butylbenzene
o-Xylene
Xylene (Total)
Acenaphthene
Acenaphthylene
Laboratory
Concentration
(WI/L)
1.3
1.3
2.6
5.3
4.4
1
1.7
17
8.6
1.3
1.1
1.9
1.1
1.3
3.4
2.9
6.5
7.8
3.1
3.1
6
10
3.5
1.8
6.9
1.9
1.4
1.1
1.6
7.2
2.2
1
18
28
2.1
3.1
81
6.4
4.4
6
110
57
2.1
14
20
27
210
Laboratory
Qualifier
Laboratory
Reporting
Limit
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
2.0
2.0
2.0
2.0
2.0
2.0
4.0
2.0
20.
2.0
2.0
6.0
10.
100
Page 1 of 4
-------
TABLE 8
ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING SA
POUDRE RIVER SITE
Point Name
FC-MW-12
FC-MW-12
FC-MW-12
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
FC-MW-15
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-10
PRBB-11
PRBB-11
PRBB-11
PRBB-11
PRBB-17D
PRBB-7
PRBB-7
PRBB-7
TTMW-02
TTMW-04
TTMW-04
Sample ID
SA-MW-07
SA-MW-07
SA-MW-07
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-09
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-13
SA-MW-05
SA-MW-05
SA-MW-05
SA-MW-05
SA-MW-02
SA-MW-01
SA-MW-01
SA-MW-01
SA-MW-12
SA-MW-15
SA-MW-15
Sample
Date
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/3/2004
8/2/2004
8/2/2004
8/2/2004
8/2/2004
8/4/2004
8/4/2004
8/4/2004
Sample
Media
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Sample
Company
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
Duplicate ID
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
SA-MW-1599
SA-MW-1599
Sample Depth
(ft)
18.5
18.5
18.5
17
17
17
17
17
17
17
17
17
17
17
17
17
17
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
35
35
35
35
38
39
39
39
27.5
28
28
Analytical
Group
SVOA
SVOA
SVOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
SVOA
SVOA
SVOA
SVOA
SVOA
SVOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
Chemical Name
Fluorene
Naphthalene
Phenanthrene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
Benzene
Ethylbenzene
m&p-Xylene
Naphthalene
o-Xylene
Xylene (Total)
2-Methylnaphthalene
Acenaphthene
Acenaphthylene
Fluorene
Naphthalene
Phenanthrene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
Acetone
Benzene
Chloroform
Ethylbenzene
m&p-Xylene
Methylene chloride
Naphthalene
o-Xylene
Styrene
Toluene
Xylene (Total)
2-Methylnaphthalene
Acenaphthene
Acenaphthylene
Fluorene
Naphthalene
Phenanthrene
1 ,2-Dichloroethene (Total)
cis-1 ,2-Dichloroethene
Methyl-tert-butyl ether
Tetrachloroethene
Acetone
Chloroform
Naphthalene
Tetrachloroethene
Acetone
Chloroform
Tetrachloroethene
Laboratory
Concentration
(WI/L)
14
39
40
16
5
7.2
9.2
13
430
7.4
21
73
26
13
16
240
12
74
22
100
74
19
130
140
19
2900
81
14
130
220
530
42
89
50
2600
32
1.5
1.5
4.1
1.1
100
1.7
13
30
77
1.5
7.8
Laboratory
Qualifier
J
Laboratory
Reporting
Limit
10.
10.
10.
5.0
5.0
5.0
5.0
10.
50.
5.0
15.
10.
10.
10.
10.
100
10.
10.
10.
100
10.
10.
10.
20.
10.
500
10.
10.
10.
30.
1000
10.
10.
10.
1000
10.
1.0
1.0
1.0
1.0
10.
1.0
10.
1.0
10.
1.0
1.0
Page 2 of 4
-------
TABLE 8
ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING SA
POUDRE RIVER SITE
Point Name
TTMW-04
TTMW-04
TTMW-05
TTMW-08
TTMW-08
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-10
TTMW-1 1
TTMW-1 1
TTSB-09
TTSB-09
TTSB-09
TTSB-11
TTSB-11
TTSB-11
TTSB-14
TTSB-14
TTSB-14
TTSB-14
TTSB-14
TTSB-14
TTSB-14
TTSB-16
TTSB-16
TTSB-16
TTSB-16
TTSB-16
TTSB-16
TTSB-16
TTSB-16
TTSB-16
TTSB-16
Sample ID
SA-MW-1599
SA-MW-1599
SA-MW-14
SA-MW-08
SA-MW-08
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-16
SA-MW-20
SA-MW-20
SA-GW-01
SA-GW-01
SA-GW-01
SA-GW-03
SA-GW-03
SA-GW-03
SA-GW-02
SA-GW-02
SA-GW-02
SA-GW-02
SA-GW-02
SA-GW-02
SA-GW-02
SA-GW-04
SA-GW-04
SA-GW-04
SA-GW-04
SA-GW-05
SA-GW-05
SA-GW-05
SA-GW-05
SA-GW-05
SA-GW-05
Sample
Date
8/4/2004
8/4/2004
8/4/2004
8/3/2004
8/3/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/4/2004
8/5/2004
8/5/2004
4/27/2004
4/27/2004
4/27/2004
5/4/2004
5/4/2004
5/4/2004
5/4/2004
5/4/2004
5/4/2004
5/4/2004
5/4/2004
5/4/2004
5/4/2004
5/6/2004
5/6/2004
5/6/2004
5/6/2004
5/6/2004
5/6/2004
5/6/2004
5/6/2004
5/6/2004
5/6/2004
Sample
Media
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Sample
Company
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
Duplicate ID
SA-MW-15
SA-MW-15
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Sample Depth
(ft)
28
28
32.5
33
33
29
29
29
29
29
29
29
29
29
29
29
29
29
29
29
29
29
33
33
18
18
18
19
19
19
19
19
19
19
19
19
19
9
9
9
9
22
22
22
22
22
22
Analytical
Group
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
SVGA
SVGA
SVGA
SVGA
SVGA
SVGA
SVGA
SVGA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
SVGA
SVGA
SVGA
SVGA
SVGA
SVGA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
Chemical Name
Chloroform
Tetrachloroethene
Tetrachloroethene
Chloroform
Tetrachloroethene
1 ,2,4-Trimethylbenzene
1 ,3,5-Trimethylbenzene
Ethylbenzene
m&p-Xylene
Naphthalene
o-Xylene
sec-Butylbenzene
Tetrachloroethene
Xylene (Total)
2-Methylnaphthalene
Acenaphthene
Acenaphthylene
Anthracene
Dibenzofuran
Fluorene
Naphthalene
Phenanthrene
Acetone
Tetrachloroethene
Chloromethane
Naphthalene
Tetrachloroethene
Naphthalene
Tetrachloroethene
Trichloroethene
Naphthalene
2-Methylnaphthalene
Acenaphthene
Acenaphthylene
Fluorene
Naphthalene
Phenanthrene
Acetone
Chloroform
Tetrachloroethene
Trichloroethene
1 ,2-Dichloroethene (Total)
Acetone
cis-1 ,2-Dichloroethene
Methyl-tert-butyl ether
Tetrachloroethene
Trichloroethene
Laboratory
Concentration
(WI/L)
1.6
8.2
1.8
1.7
30
38
10
8.4
6.6
1300
13
32
33
20
510
36
170
14
13
69
1100
54
13
3.2
1.4
6
2.7
19
5.9
1.5
72
44
12
29
37
38
48
12
6.7
1
1.5
1.1
19
1.1
1.5
2.9
2.8
Laboratory
Qualifier
J
J
J
J
J
J
Laboratory
Reporting
Limit
1.0
1.0
1.0
1.0
1.0
20.
20.
20.
40.
200
20.
20.
20.
60.
200
10.
200
10.
10.
10.
200
10.
10.
1.0
1.0
5.0
1.0
5.0
1.0
1.0
5.0
10.
10.
10.
10.
10.
10.
10.
1.0
1.0
1.0
1.0
10.
1.0
1.0
1.0
1.0
Page 3 of 4
-------
TABLE 8
ORGANIC COMPOUNDS DETECTED IN GROUNDWATER DURING SA
POUDRE RIVER SITE
Point Name
TTSB-17
TTSB-17
TTSB-17
TTSB-18
TTSB-18
TTSB-19
TTSB-19
TTSB-20
TTSB-20
TTSB-20
TTSB-20
Sample ID
SA-GW-06
SA-GW-06
SA-GW-06
SA-GW-07
SA-GW-07
SA-GW-08
SA-GW-08
SA-GW-09
SA-GW-09
SA-GW-10
SA-GW-10
Sample
Date
5/7/2004
5/7/2004
5/7/2004
5/10/2004
5/10/2004
5/10/2004
5/10/2004
5/11/2004
5/11/2004
5/11/2004
5/11/2004
Sample
Media
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
WATER
Sample
Company
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
TTEMI
Duplicate ID
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Sample Depth
(ft)
17.5
17.5
17.5
19
19
19
19
19
19
19
19
Analytical
Group
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
VOA
Chemical Name
Chloromethane
Methyl-tert-butyl ether
Tetrachloroethene
Tetrachloroethene
Trichloroethene
Acetone
Tetrachloroethene
Tetrachloroethene
Trichloroethene
Tetrachloroethene
Trichloroethene
Laboratory
Concentration
(WI/L)
2
4.8
3.5
4.9
4
28
21
4.7
3
4.3
2.8
Laboratory
Qualifier
Laboratory
Reporting
Limit
1.0
1.0
1.0
1.0
1.0
10.
1.0
1.0
1.0
1.0
1.0
Notes:
ft Feet
J Estimated value
|ag/L Microgram per liter
NA Not applicable
SVOA Semivolatile organic analysis
TTEMI Tetra Tech EM Inc
VOA Volatile organic analysis
Page 4 of 4
-------
TABLE 9
Notes:
B
E
T
X
RATIO OF (B+T)/(E+X) BY SAMPLE LOCATION
POUDRE RIVER SITE
Benzene
Ethylbenzene
Toluene
Xylene
Sample Location
MGPMW-1S
MW-2
MGPMW-3S
FC-MW-12
FC-MW-15
Average:
(B+T)/(E+X) ratio
3.76
7.79
0.12
3.07
0.24
3.00
-------
TABLE 10
COST COMPARISON BETWEEN A TRADITIONAL APPROACH AND THE TRIAD
APPROACH
POUDRE RIVER SITE
T|jj|t|j|isfl|jptt0t
Background review, project
planning, preparation of the
work plan, and site visit for the
first mobilization of the TEA.
Background review, project
planning, preparation of the
work plan, and site visit for the
second mobilization3 of the
TEA. The second
mobilization is assumed
necessary to collected data for
data gaps identified during the
first mobilization of the TEA.
First mobilization for the
TEA. Field investigation
including pre-field work and
post-field paperwork
Second mobilization for the
TEA. Field investigation
including pre-field work and
post-field paperwork,3
Sample analysis, interaction
with labs, and data validation
for the first TEA mobilization.
Eppr
I|iffil^=
••
400
300
N/A
300
650
450
N/A
300
80
160
HM^=
fSMbrttP"
STS/ftwiB
$30,000
$22,500
N/A
$22,500
$48,750
$33,750
N/A
$22,500
$6,000
$12,000
Subcontractor Costs
N/A
N/A
N/A
N/A
$45,00 Driller
$12,000 Geophysics
$800 IDW
$30,000 Driller
$800 IDW
N/A
$20,000 Driller
$800 IDW
Soil Gas Survey
$65,000
Mobile Laboratory
(provided by EPA
Region 8)
$17,500 Fixed lab
VOC, SVOC, TPH,
Pest/PCB, and metal
analyses
CLP lab analyses
(provided by EPA
Region 8)
$86,000 Fixed lab
VOC, SVOC, TPH,
Pest/PCB, and metal
analyses
gPJgg&BB
$500
$500
N/A
$500
$10,000
$8,000
N/A
$6,000
N/A
N/A
N/A
N/A
N/A
Estimated
TniHtloMiCaH
$30,500
$23,000
N/A
$23,000
$116,550
$72,550
N/A
$49,300
$71,000
$0
$17,500
$0
$98,000
-------
TABLE 10
COST COMPARISON BETWEEN A TRADITIONAL APPROACH AND THE TRIAD
APPROACH
POUDRE RIVER SITE
TaakUteseriptiwi
Sample analysis, interaction
with labs, and data validation
for the second mobilization3 to
address data gaps identified
during the initial phase of the
TEA
Data evaluation, TEA report
preparation, and file closeout
for the first mobilization
Data evaluation, TEA report
preparation, and file closeout
for the second mobilization3
Background review, project
planning, preparation of the
work plan, and site visit for the
first mobilization of the S A.
Background review, project
planning, preparation of work
plan, and site visit, for the
second mobilization3 of the
SA. The second mobilization
is assumed necessary to collect
data for data gaps identified
during the initial phase of the
SA.
First mobilization for the SA
Field Investigation including
pre-field work and post-field
paperwork
Second mobilization for the
SA. Field Investigation
including pre-field work and
post-field paperwork3
Sample analysis, interaction
with labs, and data validation
for the first mobilization of the
SA.
fjjfyr j
•OBI* CiBilPi
N/A
80
300
200
N/A
200
300
250
N/A
250
650
450
N/A
300
250
250
N/A
$6,000
$22,500
$15,000
N/A
$15,000
22,500
$18,750
N/A
$18,750
$48,750
$33,750
N/A
$22,500
$18,750
$18,750
Subcontractor Costs
N/A
$26,000 Fixed lab
VOC, SVOC, TPH,
Pest/PCB, and metal
analyses
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
$85,00 Driller
$24,000 Geophysics
$1,600 IDW
$85,000 Driller
$1,600 IDW
N/A
$40,000 Driller
$800 IDW
$28,500 Fixed lab
VOC, SVOC analyses
$28,500 Fixed lab
VOC, SVOC analyses
N/A
N/A
$1,000
$1,000
N/A
$1,000
$500
$500
N/A
$500
$16,000
$16,000
N/A
$6,000
N/A
N/A
Actual (ostl!Mn»
-------
TABLE 10
COST COMPARISON BETWEEN A TRADITIONAL APPROACH AND THE TRIAD
APPROACH
POUDRE RIVER SITE
Igfctf-fiHjpttaft
Sample analysis, interaction
with labs, and data validation
for the second mobilization of
the SA. The second
mobilization is assumed
necessary to collect data for
data gaps identified during the
initial phase of the SA.
Data evaluation, SA report
preparation, and file closeout
for the first mobilization
Data evaluation, SA report
preparation, and file closeout
for the second mobilization
Consultations about use of
Triad approach
Totals
Percent savings using the
Triad approach
H"UrS
N/A
250
200
200
N/A
200
200
N/A
3,030
4,140
36%
feiKf'""""""
-taita^
N/A
$18,750
$15,000
$15,000
N/A
$15,000
$15,000
N/A
$227,250
310,500
36%
Subcontractor Costs
N/A
$28,500 Fixed lab
VOC, SVOC analyses
N/A
N/A
N/A
N/A
N/A
N/A
$279,400
348,000
25%
N/A
N/A
$1,000
$1,000
N/A
$1,000
$1,500
N/A
$30,500
42,000
27%
Actual Cost Using
the Triad vs.
N/A
$71,000
$16,000
$16,000
N/A
$16,000
$16,500
N/A
$537,150
700,500
30%
Notes:
TRADITIONAL
Costs associated with the Triad approach
Estimated costs from a traditional approach
a A second mobilization and sampling event was assumed as a requirement under a
traditional approach.
b ODCs: Includes copies, phone, sample shipment, computer time, field equipment rentals
and supplies including test kits and fluorescence detector for TPH and PAH field
analyses, travel, per diem, vehicle rental, gasoline etc.
IDW Investigation-derived wastes
N/A Not applicable
ODC Other direct cost
PAH Polynuclear aromatic hydrocarbon
SA Site Assessment
SVOC Semivolatile organic compound
TEA Targeted Brownfields Assessment
TPH Total petroleum hydrocarbon
VOC Volatile organic compound
-------
FIGURES
-------
Location Map
Railroad
Street
Water
Site Outline
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE
SITE LOCATION
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
List of Area Structures
1 -H istorical Power Plant Site
2 -c SU Engines and Energy Conversion Lab
3 -R apid Lube
4 -j he Family Center
5 - Scout 66 Gas Station
6 -A Classic Touch
7 -3 chrader Oil Company Maintenance Facility
8 -5 chrader Oil Company Bulk Plant
9 -H istorical Gas Plant
10 -Q iddings Machine Shop
11 - Interstate Batteries
12-c lear Cut Glass
13 -£ ducation and Life Training Center
14- El Burrito
15 -R anchway
16 -|\| orthern Colorado Feeders Supply
17 -R anchway
18 -5 chrader Building
19 -y nited Way Building
20 -p ublic Service Company
21 -p layground
A - Northside Aztlan Center
G -Q as Holders
R - Residential
CD
O>
o
O
Fort Collins
COLORADO
X\/
i _ _ i
Location Map
Cross-Section Transect
Paved Area
Recreation Path
Railroad
Proposed Barrier Wall
Proposed Barrier Wall Easement
Proposed IWTP
Building
Approximate Extent of Observed
Fill and Trash Debris
Approximate Extent of Old Landfill
Site Outline
Former Location of Poudre
Valley Gas Company
Schrader Oil or Public Service
Company Property
200
400
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 2
SITE LAYOUT
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
* ** 4
Fort Collins
COLORADO
Location Map
T-1: Terracon Bore Hole Location
Product Sample Location
Paragon Monitoring Well Location
Schrader Monitoring Well Location
Soil Boring Location
BTH-14: Walsh Well Location
Recreation Path
Current River Channel
Test Pit
Building
Proposed Aztlan Recreation Center
Approximate Extent of Former Landfill
Approximate Extent of Observed
Fill and Trash Debris
Site Outline
Previous Location of Poudre
Valley Gas Company
Schrader Oil or Public Service
Company Property
Note: Aerial Photo from USGS, July 14, 1951.
75 150
300
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 3
HISTORICAL SAMPLE LOCATIONS
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
R:\EPA\Aztlon CenterX Aztlan-old.dwq 08/07/2006 deboroh.ford DN
FORMER
NATURAL
GAS PLANT
TANK HOLDER
AZTLAN CENTER
GROUND
SURFACE
-... ••.-.
•.-.-. •-•-•"•'• •.•/.•. •.•-'-"->...-. .-.• •.•.•-•.'-'-"-. .-.- .-.-. '-'•'•'•'•.-.-.
• ' v. -.v.;v -- -".ilv.v. •.-.••.•.••••.• •
B--d
0-V?»Xo
.Bv*.;.o.-,-oy
-------
Fort Collins
COLORADO
Location Map
Legend
L '
Current River Channel
Bed rock Contour
(1 foot contour)
Building
Proposed Aztlan Recreation Center
Historical River Channel (1906)
Approximate Extent of Observed
Fill and Trash Debris
Landfill Outline
Approximate Boundary of NAPL Impacts
Observed in Unconsolidated Alluvium
and Bedrock (dashed where inferred)
Site Outline
Previous Location of Poudre
Valley Gas Company
Schrader Oil or Public Service
Company Property
Note: Bedrock surface elevations interpolated
rehole logs from previous
ation (UOS Phase I).
from bo
investig
75
150
300
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 5
PRELIMINARY BEDROCK SURFACE CONTOUR
MAP WITH FORMER RIVER CHANNEL
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
Primary Source
Primary
Release Mech.
Secondary
Source
FIGURE 6
Pathway Receptor Diagram
Atzlan Center, Fort Collins
Secondary
Release Mech.
Pathway
Exposure
Route
Receptor
Human Biota
Recreational Residential Terrest. Aquatic
Landfill
Solids/Liquids
and
Upgradient
Sources
Direct
Placement
Surface
Water Run off
Creek Water
Creek Sediments
>•
Ingestion
Dermal
•
•
O
O
•
•
•
•
Creek Water
Creek Sediments
Surface
Water
Ingestion
Inhalation
Dermal
O
O
O
o
o
o
o
o
o
o
o
o
Infiltration/
Percolation
Subsurface
Soil
Ingestion
Inhalation
Dermal
O
O
O
o
o
o
o
o
o
o
o
o
Landfill
Gas and
Upgradient
Plumes
Volatile
Emissions
Indoor Air
Ingestion
Inhalation
Dermal
Physical Hazard
O
O
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o:\aztlan_center\prcs\pathway receptor diagram.doc
• Completed pathway
O Possible complete pathway (data required)
O Incomplete pathway
-------
„'_•_ _ '1 _Nfirthside*
/Aztlan Ce,nte
Fort Collins
COLORADO
Location Map
T-1 : Terracon Bore Hole Location
Product Sample Location
Paragon Monitoring Well Location
Schrader Monitoring Well Location
Soil Boring Location
BTH-14: Walsh Well Location
Recreation Path
/\/ Current River Channel
Estimated Extent of Napthalene in
Groundwater, dashed where
approximate (Walsh)
Building
Proposed Aztlan Recreation Center
Approximate Extent of Observed
Fill and Trash Debris
Approximate Extent of Former Landfill
Site Outline
Previous Location of Poudre
Valley Gas Company
Schrader Oil or Public Service
Company Property
Approximate Boundary of
Historic Gas Holder
Note: Aerial Photo from USGS, July 14, 1951.
75 150
300
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 7
NAPHTHALENE CONCENTRATIONS IN
GROUNDWATER. PRE-TBA
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
Figure 8
TBA - Sample Collection
Decision Logic Diagram
/Advance the Direct Push Sampling Tooi\
I to the Top of Groundwater and Collect a 1
V Grab Water Sample J
Analyze the Water Sample
Headspace With a PID/FID
and the HAPSITE Field
Portable GC/MS.
At Five Direct Push Locations (1 Adjacent to the River
Product Sample and up to 4 Additional Locations
Based on the Geophysical Survey Results) Continue
to Advance the Direct Push Sample Collection Tool to
Progressively Deeper Intervals Down to the Bedrock
Interface. Collect up to 4 Additional Grab
Groundwater Samples at Depth and Screen With a
PID/FID and Analyze With the HAPSITE Field
Portable GC/MS. Sample Collection Depths Will Be
Based on Rate of Advancement of the Direct Push
Sampling Tool and Professional Judgement of the
Field Team.
Is Small Scale Heterogeneity Indicated Based on the Analytical
Results of Samples Collected at Various Depths Within the First
Five Direct Push Sampling Locations?
Yes
Reevaluate Decision Criteria
For Collection of Grab
Groundwater Samples and
Adjust Decision Logic As
Necessary.
Apply Original Decision Criteria
Advance the Direct Push Sampling Tool to the Top of
Groundwater and Collect a Grab Water Sample
Analyze the Groundwater
Sample Headspace With a
PID/FID.
Is the PID/FID Result Greater Than 100
Parts Per Million (PPM)?
-No-,
Drive the Direct Push Core to
the Top of Bedrock and Collect
1 Additional Groundwater
Sample. Screen the Sample
With the FID/PID and Analyze
with the HAPSITE GC/MS.
s Free Product Evidenced?
No f
Analyze the Sample
With the HAPSITE
GC/MS.
Collect a Soil Sample
and Perform a Visual
Inspection. Archive a
Portion for Fixed
Laboratory Analysis
Prepare Soil
Sample
Methanol Extract
Report Results
-------
Fort Collins
COLORADO
Location Map
Legend
I
Recreation Path
Geophysical Surveyed
Transect Lines
Building
Proposed Aztlan Recreation Center
Approximate Extent of Observed
Fill and Trash Debris
Approximate Extent of Former Landfill
Site Outline
Previous Location of Poudre
Valley Gas Company
Schrader Oil or Public Service
Company Property
75
A
150
300
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 9
TBA - GEOPHYSICAL GRID SPACING
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
900
1000
1100
1200
1300
1400
1500
1600
N
5
Bedrock Contour - 1 foot
1600
milliSiemens/meter
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 10
TBA - GEOPHYSICAL
ELECTROMAGNETIC
SURVEY RESULTS MAP
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
900
1000
1100
1200
J300
1400
1500
1600
Bedrock Contour - 1 foot
»
- 0 * • I
" ' *
900
1100
1200
1300
1400
1500
'600
Bedrock Contour-1 foot
Relative Response
Sccle 1:1000
SO 0 bO 100
^^^H
feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 1 1
TBA - GEOPHYSICAL METAL
DETECTION SURVEY RESULTS MAP
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
SW-3
- :',
/, ^ FC-TW-02^
• • ,"*• \\
V, , A FC-GW-43,
v\ \
V>\A FC-GV\^44
'•'-'. \
'•'•'. » FC-GW-45
Y
V' , FC-MW-03
••'. ^ X
> • '• A FC-GW-02
\v \
\
. ', ^ FC-GW-03
':;:;, \
~~'.-- A FC-GW-04
-% *\
'A FC-GW-O^
FC-MW-04
1
^Qj \ • SW-1
FC-GW-07<
^>
^FC-GW-Oa^
v;,^ \
BTH-H-.-T, ^_*,JC-MW-05
\
Fort Collins
COLORADO
Location Map
Direct Push Groundwater Grab
Sample Location
Tetra Tech EMI Inc. Small Gauge
Temporary Monitoring Well
Monitoring Well
Surface Water Sample Location
Naphthalene Contour
Recreation Path
Paved Area
Railroad
Building
•; Approximate Extent of Observed
" Fill and Trash Debris
_| Approximate Extent of Former Landfill
Site Outline
Former Location of Poudre
Valley Gas Company
I Schrader Oil or Public Service
4 Company Property
y Former Tar Pit
! Former Underground Storage Tank
75
N
150
300
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 12
TBA - NAPHTHALENE CONCENTRATIONS
IN GROUNDWATER
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
^ FC-GW-42*
-g Fort Collins
COLORADO
Location Map
Direct Push Groundwater Grab
Sample Location
Tetra Tech EM Inc. Small Gauge
Temporary Monitoring Well
Monitoring Well
Surface Water Sample Location
PCE Contour (dashed where approximate)
5 feet contour interval
Recreation Path
Paved Area
Railroad
Building
Approximate Extent of Observed
Fill and Trash Debris
Approximate Extent of Former Landfill
Site Outline
Former Location of Poudre
Valley Gas Company
Schrader Oil or Public Service
Company Property
Former Tar Pit
[ _________ ! Former Underground Storage Tank
L _ _
75
N
150
300
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 13
TBA - PCE CONCENTRATIONS
IN GROUNDWATER
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
COLORADO
Location Map
Soil Boring
Monitoring Well
Excel (RETEC) Test Pit
Recreation Path
Approximate Boundary of Non-Aqueous
Phase Liquid Impacts in Bedrock
(dashed where inferred)
Approximate Boundary of Non-Aqueous
Phase Liquid Impacts Observed in
Unconsolidated Alluvium
(dashed where inferred)
Approximate Boundary of Non-Aqueous
Phase Liquid Impacts Observed in
Unconsolidated Alluvium and Bedrock
(dashed where inferred)
Building
Approximate Extent of Old Landfill
Site Outline
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 14
RIVER CHANNEL INVESTIGATION
TRENCHING AND BORING LOCATIONS
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
R:\EPA\Aztlan CenterXBrownsfields Support CenterX Fiqure15_CSM-RevisedSec.dv»q 02/28/2005 deborah.ford DN
A
A'
LEGEND
_ ? _
8
TAR PIT / FORMER-7 LOT
FORMER
NATURAL
GAS PLANT
TANK
HOLDER
PRODUCTS OF
DNAPL
ACCUMULATED
BENEATH
LANDFILL
.,: ,.:. v:S'-'Sv:--wx: x •^t^x. x •••x-'^V:
ffiS®:^
- -iili-.Miii- ' "^ ^"•'•'•'•iliV
— ., — - — —, — -' — • — r - - -- -
-
POST-PINEY CREEK ALLUVIUM
(UPPER HOLOCENE)
BROADWAY ALLUVIUM
(PLEISTOCENE)
WEATHERED AND FRACTURED
PIERRE SHALE
LANDFILL
.: INTERBEDDED CALICHE/CEMENTED
til!! SANDSTONE LAYERS
PETROLEUM HYDROCARBONS AND
NAPTHALENE PLUME BOUNDARY
DENSE NON-AQUEOUS PHASE
LIQUIDS (DNAPL)
LIGHT NON-AQUEOUS PHASE
LIQUIDS (LNAPL)
_ _y _ WATER TABLE (APPROXIMATE)
WELL SCREEN INTERVAL
CACHE LA
POUDRE RIVER
NOT TO SCALE
(VERTICALLY EXAGGERATED)
NAPL PENETRATION
INTO BEDROCK
FRACTURES
Note: Line of Cross-Section shown on Figure 2.
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 15
REVISED PRELIMINARY
CONCEPTUAL SITE MODEL
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER AND
TETRA TECH EM. INC.
-------
T —^ T-M":A —
J-7 N9A » / t*\y3&- • V
H8 • FC-HW-OS/QIO «XA .R1*
TTHW-06 . N9 BTH .J'/'- ' I
BTH-15'X . •• _
,Vi2V<13A ,P13 S>^ A \
\N13 "V^ /* 'R^J9 >1
\ P14 'i)' * Si°
i M13 \TTMm.08 PRBB-21,-^ Q15 • ^
I; , . , _ , --__-•!? • «
Q19 • «
• • f»V
»R42~,
Fort Collins
COLORADO
Location Map
Legend
• Soil Boring
^ Monitoring Well
'/\-y Recreation Path
/\/ Paved Area
/\/ Railroad
| | Building
; ; Approximate Extent of Observed
' Fill and Trash Debris
i _ _ I Approximate Extent of Former Landfill
| | Site Outline
• 1 Former Location of Poudre
I 1 Valley Gas Company
Schrader Oil or Public Service
Company Property
1000 nanograms
10 nanograms
A
150
300
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 16
SA - .. PHTHALENE DETECTED
N A
IN SOIL GAS
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
PDB-14
NORM j etrachloroethene 1.4
PDB-15
NORM j richloroethene 1.2
NORM 1 2- Dichloroethene (Total) 1 7
NORM c'is-1,2-Dichloroethene 1.7
PDB-16
NORM j richloroethene 1.6
.
NORM 1 2- Dichloroethene (Total) 2
NORM c'is-1,2-Dichloroethene 2
PDB-17
NORM j etrachloroethene 3.4
NORM T richloroethene 1.2
PDB-18
NORM j etrachloroethene 2
NORM T richloroethene 1.3
PDB-19
NORM j etrachloroethene 2.3
NORM j richloroethene 1.5
PDB-20
NORM j etrachloroethene 3.9
NORM j richloroethene 1.8
PDB-24
NORM j etrachloroethene 1
NORM j richloroethene 1.5
NORM 1 2- Dichloroethene (Total) 1
NORM c'is-1,2-Dichloroethene 1.2 '
PDB-26
NORM j richloroethene 1.6
PDB-29
NORM j etrachloroethene 1
NORM j richloroethene 3.2
FD T etrachloroethene
FD-j- richloroethene 3
1.1
PDB-30
NORM j etrachloroethene 1.5
NORM j richloroethene 4.4
PDB-31
NORM j etrachloroethene 1.4
NORM j richloroethene 3.4
PDB-32
NORM i]2,3-Tricnl°robenzene 2.2
NORM i'2'4- Trichlorobenzene 1.1
NORM j etrachloroethene 2^
NORM j richloroethene 1.7
PDB-33
NORM j etrachloroethene 3.7
NORM j richloroethene 1.2
PDB-34
NORM j etrachloroethene
NORM j richloroethene 1.
4.5
.2
PDB-35
NORM j etrachloroethene 7.
NORM j etrachloroethene 1.
PDB-36
NORM j etrachloroethene 5.4
PDB-37
NORM j etrachloroethene 12
NORM j richloroethene 1.4
PDB-38
NORM j etrachloroethene 7.6
PDB-39
NORM Tetrachloroethene 18
NORM Trichloroethene 1.1
PDB-40
NORM j etrachloroethene 7.6
PDB-41
NORM genzene 2.4
NORM j etrachloroethene 5
PDB-42
NORM j etrachloroethene 1.3
NORM 1 2- Dichloroethene (total) 2.1
NORM c'is-1,2-Dichloroethene 2.1
NORM vinyl Chloride 1.2
PDB-46
NORM j etrachloroethene 13
NORM j richloroethene 1.4
NORM 1 2- Dichloroethene (total) 1.6
NORM c'is-1,2-Dichloroethene 1.6
PDB-47
NORM j etrachloroethene 9.2
NORM j richloroethene 1.6
NORM 1 2- Dichloroethene (total) 1.7
NORM c'is-1,2-Dichloroethene 1.7
Fort Collins
COLORADO
Location Map
Passive Diffusion Bag Sampling Location
Sample Location ID
PDB-31
NORM j etrachloroethene 1.4
L
Sample Result (in ug/l)
Analyte
Sample Type
(NORM = Normal
FD = Field Duplicate)
Soil Gas Sampling Location
Soil Boring
Monitoring Well
Recreation Path
Paved Area
/\/~ Railroad
| | Building
• ; Approximate Extent of Observed
' Fill and Trash Debris
Approximate Extent of Former Landfill
Site Outline
Former Location of Poudre
Valley Gas Company
Schrader Oil or Public Service
Company Property
22675 nanograms
100 nanograms
150
300
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 17
SA - TETRACHLOROETHENE DETECTED IN
SOIL GAS AND PASSIVE DIFFUSION BAG
SAMPLE LOCATIONS
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
Fort Collins
COLORADO
Location Map
Legend
• Soil Boring
^ Monitoring Well
High Resolution Resistivity Line
Geophysical Survey "Railroad Fence"
Approximate Boundary of Non-Aqueous
Phase Liquid Impacts jn Bedrock
(dashed where inferred)
Approximate Boundary of Non-Aqueous
Phase Liquid Impacts Observed in
Unconsolidated Alluvium
(dashed where inferred)
Approximate Boundary of Non-Aqueous
Phase Liquid Impacts Observed in
Unconsolidated Alluvium
and Bedrock (dashed where inferred)
Recreation Path
Paved Area
Railroad
Building
150
300
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 18
SA - HIGH RESOLUTION RESISTIVITY
GEOPHYSICAL SURVEY TRANSECT LOCATIONS
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
High Resolution Resistivity
water
line
North
PRBB-5
4080-
4900-J
50
J_J
100
J_l I I
rbike_j
patfT]
150 | | 200
i i I i i i i I
250
i i -
Distance (feet)
300 350
i I i i i i I i ii
500
550
i i I i i
600
_L
South
650
-4080
4900
HRR Line 0 (Station 0 - 650ft)
» X
*
£
4980
c 4970-
p
TO 496'
1^495
550 600 650 700
i i i i I i i i i I i i i i I
750 800
J i I I ! I
•Distance (feet)
850 900
I i i i I
X
/
950
i i i
1000 1050 1100 1150
I i i i i I i i i i i i i i i i i
Landfill/Alluvium
Bedrock
490
HRR Line 0 (Station 550-1195 ft)
EQUIPMENT
Ex: ~ AGI Sting RS
Tx: AGI Sting RS
Airay: Pole-Bole
Spacing: 5-360 ft
Electrodes: Stainless Steel
PROCESSING
Filter: None
Gridding Method: Rriging
Cell Size: 2.5x2.5
Trend Bias: None
Coordinate SSystem: Local (feet)
Apparent Resistivity (Ohm-ra)
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
150 300 450 600 750 900 1050 1200 1350 1500
Vertical Exaggeration: 1.5 : 1
0 25 50 75
Scale: 1 inch = 60 feet
100
4980
-4930
-4920
-4010
-4900
Fort Collins
COLORADO
Location Map
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 19
SA - GEOPHYSICAL RESULTS
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
xVh
v > :TSB-15 J/ | '•j-—,
x jr r~~* I
/> / I
,f "» / >—,
" •> *~~~, t~*
^^ —1
;3Vv '—_/
i . —i
V
Fort Collins
COLORADO
Location Map
Leqend
Soil Boring
Monitoring Well
Approximate Boundary of Non-Aqueous
Phase Liquid Impacts jn g edrock
(dashed where inferred)
Approximate Boundary of Non-Aqueous Phase
/\/ Liquid Impacts Observed in Unconsolidated
Alluvium (dashed where inferred)
Approximate Boundary of Non-Aqueous Phase
//." Liquid Impacts Observed in Unconsolidated
Alluvium and Bedrock (dashed where inferred)
''^\- Recreation Path
Paved Area
Railroad
Building
Approximate Extent of Observed
Fill and Trash Debris
Approximate Extent of Former Landfill
Site Outline
Former Location of Poudre
Valley Gas Company
Schrader Oil or Public Service
Company Property
i _ _ i
N
150
300
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 20
SA - BORING AND MONITORING WELL
LOCATIONS WITH EXTENT OF
COAL TAR IMPACTS
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
Fort Collins
COLORADO
Legend
Location Map
Soil Boring
Monitoring Well
Bedrock Contour (dashed where inferred)
Cross-Section Transect
Approximate Boundary of Non-Aqueous
/\/ Phase Liquid Impacts in Bedrock
(dashed where inferred)
Approximate Boundary of Non-Aqueous
Phase Liquid Impacts Observed in
/ v' Unconsolidated Alluvium
(dashed where inferred)
Approximate Boundary of Non-Aqueous
Phase Liquid Impacts Observed in
Unconsolidated Alluvium
(dashed where inferred)
i'/,'' Recreation Path
Paved Area
/\/ Railroad
| | Building
Site Outline
• - 1 Former Location of Poudre
I - 1 Valley Gas Company
t - 1 Schrader Oil or Public Service
' - ' Company Property
150
300
Feet
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 21
SA - FINAL BEDROCK SURFACE
CONTOUR MAP
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
AND TETRA TECH EM, INC.
-------
4965
4950-
4935-
4920-
CACHE LA POUDRE RIVER
GRAVELY FILL
FORMER
NATURAL
GAS PLANT
TANK
HOLDER
NORTHSIDE
AZTLAN CENTER
PLAYGROUND
WILLOW
STREET
PARKING LOT oo
SOIL/GAS
ACCUMULATION
BENEATH /
PARKING LOT
SOIL/GAS
PREFERENTIAL
PATHWAY
GROUNDWATER FLOW
DIRECTION
PDBS
LEGEND
WATER TABLE (APPROXIMATE)
POST-PINEY CREEK ALLUVIUM (UPPER HOLOCENE)
BROADWAY ALLUVIUM (PLEISTOCENE)
MASSIVE GLAUCANITIC SANDSTONE (PIERRE SHALE)
LAMINATED SILTY SANDSTONE/SILTSTONE (PIERRE SHALE)
LAMINATED, FRACTURED SILTY SANDSTONE (PIERRE SHALE)
LANDFILL MATERIAL
DNAPL-COAL TAR
HIGHLY WEATHERED FRACTURED SANDSTONE (PIERRE SHALE)
DENSE NON-AQUEOUS PHASE LIQUID (DNAPL)
PASSIVE DIFUSSION BAG SAMPLER
WELL SCREEN INTERVAL
COAL TAR
NO SCALE
HORIZONTAL VERTICAL
1:5 APPROXIMATE VERTICAL EXAGGERATION
POUDRE RIVER SITE
FORT COLLINS, COLORADO
FIGURE 22
FINAL CONCEPTUAL SITE MODEL
AND CROSS-SECTION
U.S. EPA REGION VIII
IN COOPERATION WITH
BROWNFIELDS TECHNOLOGY SUPPORT CENTER
-------
FIGURE 23
INVESTIGATION HISTORY
U.S. EPA REGION VIII IN
COOPERATION WITH BROWNFIELDS
TECHNOLOGY SUPPORT CENTER
Previous investigations
Targeted Browtiflelds Assessment
Systematic Planning/Plan Preparation
Geophysscal Survey
Grountfwater and Soil Sampling
Install welts and further sampling efforts
Prepared ISA Report
FTlR Sampling
Poudre River Site Assessment
Systematic Planning/Plan Preparation
Passive Soil Gas (PSG) Samplers
Passive Diffusion Bag (PDB) Samplers
G&optiysicaf Survey
Drilling, Soil Sampling, and Grab GrouncfwaEer Sampling
Groimdwatw level measurements taken
SA Report Prepjiratert
Cache La Poudre River Source Investigation
'A'Qfk Plan Preparation
">e River Crgnne! Trencftsng/Test Prt Activities
3? MorUonng Well Sampling
3s Rtver Jnveslsgation Report Preparation
33 Remedial Alternative Implemented by Xcel Energy
-------
APPENDICES
-------
APPENDIX 1
TECHNOLOGY QUICK REFERENCE SHEETS
-------
TECHNOLOGY QUICK REFERENCE SHEET #1
VOLATILE ORGANIC COMPOUNDS (VOC)
BY GAS CHROMATOGRAPHY/ MASS SPECTROMETRY (GC/MS)
Summary of Project-Specific Performance Information
Project Role:
Provide real time
results to guide
dynamic sampling
activities for a Triad
investigation.
GC/MS results were
used to identify
potential coal tar
related contaminants,
delineate dissolved
plumes, and place
temporary and
permanent
monitoring wells.
Analytical Information Provided:
A total of 68 analyses were performed over 6 days using a Hewlett Packard 5970 series
GC/MS. The unit was provided in a mobile laboratory vehicle by EPA Region 8 at no charge
to the project. Equipment included all necessary peripherals (computer, HP chemstation
software), auto-sampler, and Tekmar/Dohrman purge and trap unit. Analysis followed a
modified EPA SW-846 Method 8260 process using a 5-point initial calibration curve, daily
continuing calibration checks and blank analyses.
Qualified analytical chemists were provided by Tetra Tech to process samples, obtain
analytical results, evaluate sample quantitation and calibrations, and provide real time results
to the field crew for dynamic sampling activities. Additionally, samples were provided to
EPA Region 8 for comparative analysis by EPA SW-846 Method 8260. The analyses were
able to identify a significantly large dissolved plume of low level trichloroethene and
tetrachloroethene contamination not previously identified or delineated at the site.
PROJECT COST AND TIME SAVINGS
Total Cost (includes GC/MS, autosampler, purge and
trap unit, consumables, and labor): Approximately
$3,600. Mobile laboratory, instrument, and peripherals
were provided free of charge by EPA Region 8. Cost
only includes labor and some consumables.
Total Cost Per Sample (only includes labor and
consumables): $53
Estimated Total Cost Per Sample (including labor,
consumables, laboratory, instrument, and peripheral
charges): $95
Instrument Cost:
HP5970 GC/MS Purchase Price:
Approximately $45,000 to $50,000
new
Used units including auto-sampler
and purge and trap unit can be
purchased from $25,000 to
$35,000 depending on age and
configuration.
Rental Costs: Not applicable for
this project.
A certified mobile laboratory
providing Method 8260 analyses
can be procured as a service for
approximately $l,500-$2,000/day.
Consumables
Cost:
Most consumables
(standards,
methanol, helium
99.999% pure,
were provide free
of charge by EPA
Region 8).
DI water for
blanks:
$5/ gallon, 2
gallons used = $10
Ice $27 bag, 20
bags used = $40
Labor Cost:
$52/ sample
Waste Disposal
Cost:
Not available.
Samples were
disposed of with
site purge water.
Disposal cost for
small amounts of
sample, methanol,
and site
contaminants are
assumed to be
minimal.
Time Savings:
lYear
Site characterization activities
using a dynamic work strategy
were completed in several weeks.
Sufficient data to place monitoring
wells and complete the Targeted
Brownfields Assessment (TEA)
were completed in a single funding
cycle (1 year). Site
characterization following a
traditional phased approach would
have required multiple
mobilizations taking place over 2
years, which encompasses 2 cycles
of Brownfields funding.
Site-Specific Precision and Accuracy Achieved:
Duplicate Samples evaluated using
Relative Percent Difference (RPD): RPD =
Throughput Achieved:
68 Analyses
A-B
(A-B)I2
xlOO
Duplicate RPDs for detected compounds ranged from 0.56% to 33%
Comparability = (Field Result/ EPA Region 8 Fixed Laboratory Result) X 100
Comparability results ranged from 4% to 38%
-------
TECHNOLOGY QUICK REFERENCE SHEET #1 (CONTINUED)
VOLATILE ORGANIC COMPOUNDS (VOC)
BY GAS CHROMATOGRAPHY/ MASS SPECTROMETRY (GC/MS)
General Commercial Information (Information valid as of September 2003)
Vendor Contact:
Rene Beleau
(303)312-7713
Vendor Information:
EPA Region 8 Laboratory
16194 W 45th Drive
Golden, Colorado 80403
U.S.A.
303-312-7700
Limitations on Performance:
The system employed a purge and trap configuration and auto-
sampler with the GC/MS. An initial 5-point calibration curve was
developed and spiked surrogates, daily continuing calibration
checks, blanks, and duplicate analyses were performed as part of
the QA/QC program. Samples were analyzed following a
modified SW-846 Method 8260 process (limited QC); however,
results were verified by comparative analysis of samples using a
complete SW-846 method at the EPA Region 8 laboratory.
Principle of Analytical Operation:
This analysis is based on a 5 milliliter sample
purge using an inert gas followed by collection on
a trap system. Contaminants are then desorbed
from the trap and are injected directly onto the
gas chromatograph column using an auto-sampler
system. The system is flushed after each sample
analysis.
The entire purge and trap sampling system is
automated and results were graphed electronically
by using HP CHEMSTATION software.
Dilutions were made as necessary to samples that
exceeded the calibration range.
Availability/Rates:
The EPA Region 8 mobile laboratory is available to assist in
analysis of samples for investigations at START, Brownfields,
and Superfund site cleanups. Requests should be submitted to the
EPA Region 8 Laboratory.
Power Requirements:
The mobile laboratory provides all of its own power and is
completely serf-contained. The mobile laboratory comes
complete with all the tools to perform purge and trap collection
with a Hewlett Packard GC for analysis.
Instrument Weight and/or Footprint:
Bench-top GCs weigh between 100 and 200 pounds, but can be
less than 100 pounds. Laboratory space required is controlled by
the need for sample preparation and extraction. Documentation
can also increase the need for additional space in the laboratory.
GENERAL PERFORMANCE INFORMATION
Interferences are limited to matrix effects. The method was conducted according to specifications provided under
EPA SW-846 Method 8260.
Applicable Media/Matrices:
Soil/Water
Wastes Generated
Requiring Special Disposal:
Low level contaminated
water samples from sample
contaminants, surrogates, and
matrix spikes.
Analytes Measurable with
Expected Detection Limits:
SW-846 target analytes
Detected compounds were
quantitated above the lowest standard
(20ug/L) and reported as estimated to
the detection limit (lug/L).
Other General Accuracy/Precision
Information:
Quantitative and qualitative results are
provided by GC/MS analysis.
The method was conducted according to
specifications provided under EPA SW-846
Method 8260.
Rate of Throughput:
Sample preparation (purge and trap) is about
5 to 8 minutes per sample. Analysis of
individual samples can be completed in
approximately 20 minutes.
-------
TECHNOLOGY QUICK REFERENCE SHEET #2
EMFLUX PASSIVE SOIL GAS SAMPLING SYSTEM
ANALYSIS BY GAS CHROMATOGRAPHY/ MASS SPECTROMETRY (GC/MS)
Summary of Project-Specific Performance Information
Project Role:
Guide dynamic sampling
activities for a Triad
investigation. Provide
full site coverage for soil
gas analysis. GC/MS
results were used to
identify potential coal tar
related contaminants,
refine dynamic sampling
strategies for drilling
activities, delineate soil
gas plumes, and refine
placement of temporary
and permanent monitoring
wells.
Analytical Information Provided:
Of the 333 EMFLUX soil gas samplers installed, 329 were recovered and analyzed
following procedures outlined in EPA SW-846 Method 8260. Several target compounds
beyond the typical Method 8260 list were also requested for analysis. Additional
reported compounds included 2-methylnaphthalene and total aliphatic hydrocarbons.
The EMFLUX System uses state-of-the-art, hydrophobic adsorbent materials that have a
strong affinity for the targeted compounds and do not have to compete with water
molecules.
EMFLUX samplers were installed according to Beacon Analytical guidelines
http://www.emflux.com/default.htm and left in sampling locations for approximately 25
days. The extended sampling time was used to increase sensitivity associated with less
volatile target compounds expected at the site. Relative results were provided in
nanograms per trap units and concentrations were estimated using the EMFLUX timing
model. Relative results in the form of isopleth maps were developed by Beacon
Analytical based on sorbent analysis, sampling time, earth tidal influence, and the
EMFLUX timing model.
Project Cost and Time Savings
Total Cost (includes sampling labor,
consumables, and analyses):
Installation labor= $6,480
Removal labor= $3,780
Samplers plus analysis= $140/sample= $46,620
Prepare and ship samples= $2,450
Total= $59,330
Total Cost Per Sample (includes labor, analysis and
consumables): $180
Instrument Cost:
Not applicable for this
technology as analysis
costs are included in
sampler purchase price.
Samples analyzed
following procedures
outlined in EPA SW-846
Method 8260.
Rental Costs: Not
applicable for this project
Consumables
Cost:
Not applicable.
Consumable
costs were
included in
sampler and
analysis price.
Labor Cost:
$3II sample
Waste Disposal Cost:
Not applicable. All samples
were disposed of at Beacon
Analytical laboratory at no
additional cost. Copper
pipes used during sample
deployment and
equilibration were recycled
and other associated waste
was disposed of in a trash
bin provided at the site.
Time Savings:
1 Year
Site characterization activities using a
dynamic work strategy were completed
in several weeks. Sufficient data to
place monitoring wells and complete
the Targeted Brownfields Assessment
(TEA) were completed in a single
funding cycle (1 year). Site
characterization following a traditional
phased approach would have required
multiple mobilizations taking place
over 2 years, which encompasses 2
cycles of Brownfields funding.
Site-Specific Precision and Accuracy Achieved:
Duplicate Samples evaluated using
Relative Percent Difference (RPD) RPD= ^A'B^ X 100
(A + B)/ 2
Duplicate RPDs for detected compounds range from 4.5 % to 28%
Throughput Achieved:
329 Analyses
-------
TECHNOLOGY QUICK REFERENCE SHEET #2 (CONTINUED)
EMFLUX PASSIVE SOIL GAS SAMPLING SYSTEM
ANALYSIS BY GAS CHROMATOGRAPHY/ MASS SPECTROMETRY (GC/MS)
General Commercial Information (Information valid as of September 2003)
Vendor
Contact:
Harry O'Neill
800-878-5510
Vendor
Information:
Beacon
Environmental
Services, Inc.
Telephone: 800-878-
5510
info@emflux.com
Limitations on Performance:
Because the EMFLUX® system relies on diffusion of soil gas from
subsurface sources such as contaminated soil or groundwater, the
performance range for the EMFLUX® system may be controlled by factors
such as depth to the contaminant source, contaminant concentrations and
diffusion rates, soil type and organic content, and the detection limits of the
methods used to analyze the samples. It should be noted that the
EMFLUX® system is a field screening technique useful for identifying
compounds of potential concern and potential contaminant hotspots.
Analytical results only provide an estimate (relative concentration in
nanograms per trap) of the actual concentration of contaminants in soil gas.
Principle of Analytical Operation:
The EMFLUX ® system is a passive soil gas sampling
technology designed for use in shallow deployment to
identify and estimate relative concentrations of a broad
range of VOCs and SVOCs, including halogenated
compounds, petroleum hydrocarbons, polynuclear aromatic
hydrocarbons, and other compounds present at depths to
more than 200 feet. For this project, the EMFLUX® system
consisted of 2 EMFLUX® sample cartridges, sample
insertion tools, and developer-provided sample analysis.
Each EMFLUX® cartridge consists of 100 milligrams of
sorbent sealed in a fine-mesh screen, which is placed in a
glass vial. This assembly is inserted into the soil, but only
the cartridge is thermally desorbed and analyzed in the
laboratory. The EMFLUX® field collector was installed by
drilling a three foot deep hole using a hammer drill,
inserting a copper pipe in the upper foot of the hole, and
inserting the sampler manually inside the pipe. The sampler
is covered with tin foil and then surface soil (or cement in
asphalt applications) to reduce the potential for sorption of
airborne contaminants. The cartridge was retrieved by hand
and analyzed by the developer. The EMFLUX ® system
also includes computer modeling by Beacon using a
proprietary model to predict periods of maximum soil gas
emission for geographic locations and optimize sampling.
Availability/Rates:
EMFLUX soil gas sampling system is available
through Beacon Environmental Services, Inc. $85.00 to
$195.00 per sample.
Power Requirements:
Electricity or diesel generators are required to power
drills for installation of EMFLUX samplers.
Instrument Weight and/or Footprint:
Not applicable.
GENERAL PERFORMANCE INFORMATION
Interferences are limited to matrix effects. The method was conducted according to specifications provided under
EPA SW-846 Method 8260.
Applicable
Media/Matrices:Soil gas
Wastes Generated Requiring
Special Disposal:
None
Analytes Measurable with
Expected Detection Limits: A
broad range of VOCs and SVOCs,
including halogenated compounds,
petroleum hydrocarbons, polynuclear
aromatic hydrocarbons, and other
compounds.
Other General Accuracy/Precision
Information:
Concentrations returned are relative and
reported in nanograms per trap (sorbent).
Rate of Throughput:
Rate of installation ranged from 8 to 15
minutes. Retrieval times were typically less
than 5 minutes.
-------
TECHNOLOGY QUICK REFERENCE SHEET #3
PASSIVE DIFFUSION BAG SAMPLERS
ANALYSIS BY GAS CHROMATOGRAPHY/ MASS SPECTROMETRY (GC/MS)
Summary of Project-S
aecific Performance Information
Project Role:
Guide dynamic sampling
activities for a Triad
investigation. Provide an
evaluation of contaminant
concentrations for
groundwater discharge
reaching site surface water
(Cache La Poudre River).
GC/MS results were used
to identify potential coal tar
related contaminants and
chlorinated solvents
entering surface water from
site groundwater.
Analytical Information Provided:
Forty seven passive diffusion bag (PDB) samplers were installed along the west bank of
the Cache La Poudre River and an additional 3 samplers were placed in permanent
monitoring wells along the river to correlate up-gradient groundwater concentrations
with those detected along the river bank. PDB samplers installed in the monitoring
wells were evaluated to ensure concentrations detected in nearby riverbank samples
could be considered representative of groundwater reaching surface water discharge
points. Five field duplicate samples were also collected from riverbank PDB
samplers. Samplers were allowed to equilibrate for 2 weeks, then removed and placed
in VOA vials for analysis following procedures outlined in EPA SW-846 Method 8260.
PDB samplers installed in the monitoring wells were placed near the top of the well
screen and close to the groundwater surface while samplers placed in the riverbank
were installed in shallow (approximately 2-4 feet) hand dug holes where groundwater
was visually observed entering the hole from an up-gradient direction.
Project Cost and Time Savings
Total Cost (includes sampling labor, consumables,
and analyses): Installation labor= $3,600
Removal labor= $ 1,200
Samplers $28/sample= $1,540 (includes field
duplicates)
Sample analysis $120/sample= $6,600
Total= $12,940
Total Cost Per Sample (includes labor, analysis and
consumables): $235
Instrument Cost:
Not applicable for this
technology as analysis
costs are included in
sampler purchase price.
Samples analyzed
following procedures
outlined in EPA SW-846
Method 8260.
Rental Costs: Not
applicable for this project
Consumables Cost:
Not applicable.
Consumables were not
required. Costs were
included in sampler and
analysis price.
Labor Cost:
$877 sample
Waste Disposal
Cost:
Waste disposal costs
were not applicable
for this technology.
All samples were
disposed of at Pace
Analytical laboratory
at not additional cost.
Used PDB samplers
were disposed of in a
trash bin provided at
the site.
lYear
Time Savings:
Site characterization activities using
a dynamic work strategy were
completed in several weeks.
Sufficient data to place monitoring
wells and complete the Targeted
Brownfields Assessment (TEA) were
completed in a single funding cycle
(1 year). Site characterization
following a traditional phased
approach would have required
multiple mobilizations taking place
over 2 Brownfields funding cycles (2
years).
Site-Specific Precision and Accuracy Achieved:
Duplicate Samples evaluated using
Relative Percent Difference (RPD) RPD=
Throughput Achieved:
55 Analyses
X100
(A + B)/ 2
Duplicate RPDs for detected compounds range from 6% to 15%
-------
TECHNOLOGY QUICK REFERENCE SHEET #3 (Continued)
PASSIVE DIFFUSION BAG SAMPLERS
ANALYSIS BY GAS CHROMATOGRAPHY/ MASS SPECTROMETRY (GC/MS)
General Commercial Information (Information valid as of September 2003)
Vendor Information:
Columbia Analytical Services
Telephone: 800-695-7222
www@caslab.com
Eon Products
Telephone: 800-474-2490
www.eonpro.com
Limitations on Performance:
Passive diffusion bag (PDB) samplers integrate concentrations over time. This can
be a limitation if the goal is to collect a representative sample at a point of time in an
aquifer where VOC concentrations change substantially over time faster than the
PBD samplers can equilibrate. PDB samplers are not appropriate for all compounds.
VOC concentrations in the PDB samplers may not reflect those of the surrounding
aquifer if the well screen or sand-pack are less permeable than the surrounding
aquifer and divert flow lines around the well. VOC concentrations in PDB samplers
represent ground-water concentrations in the vicinity of the screened or open well
interval that move to the sampler under ambient flow conditions. This is a limitation
if the ground-water contamination lies above or below the well screen or open
interval. In cases where the well screen or open interval transects zones of differing
hydraulic head and variable contaminant concentrations, VOC concentrations
obtained using a PDB sampler may not reflect the concentrations in the aquifer
directly adjacent to the sampler because of vertical transport in the well. This can be
mitigated by using a vertical array of PDB samplers.
Principle of Analytical Operation:
A typical PDB sampler consists of a low-density
polyethylene (LDPE) tube closed at both ends and
containing deionized water. VOCs travel across the
membrane and equilibrate with groundwater or
surface water concentrations. The sampler is
positioned at the target horizon of the well or surface
water by attachment to a weighted line or fixed pipe.
The rate that the water within the PDB sampler
equilibrates with ambient water depends on multiple
factors, including the type of compounds being
sampled and the water temperature. The samplers
should be left in place long enough for the water,
contaminant distribution, and flow dynamics to re-
stabilize following sampler deployment. Laboratory
and field data suggest that 2 weeks of equilibration is
adequate for most applications. In less permeable
formations, longer equilibration times may be
required. After the equilibration period the PDB
sampler is extracted and the water inside
immediately drained into VOA vials and sent to the
laboratory for analysis.
GENERAL PERFORMANCE INFORMATION
Availability/Rates:
Passive diffusion bag samplers are currently available through
the two distributors provided above. Costs vary from
approximately $17.00 to $32.00 per unit depending on the type
and quantity purchased.
Power Requirements:
Not applicable.
Instrument Weight and/or Footprint:
Not applicable.
Interferences are limited to matrix effects. The method was conducted according to specifications provided under EPA
SW-846 Method 8260.
Applicable Media/Matrices:
Water
Wastes Generated Requiring
Special Disposal:
None
Analytes Measurable with
Expected Detection Limits:
Volatile organic compounds.
Detection limits are determined
in accordance with EPA SW-846
Method 8260.
Other General Accuracy/Precision
Information:
Quantitative and qualitative results are provided
by GC/MS analysis.
Rate of Throughput:
Installation and retrieval times are minimal.
Equilibration period is approximately 2 weeks.
-------
TECHNOLOGY QUICK REFERENCE SHEET #4
GEONICS LIMITED EM31 AND EM34
TERRAIN CONDUCTIVITY METERS
Summary of Project-Specific Performance Information
Project Role:
Guide dynamic sampling
activities for a Triad
investigation. Provide an
evaluation of shallow
subsurface geology to refine
the conceptual site model.
Results can also be
interpreted to assist in
identification of preferential
contaminant migration
pathways as well as locate
potential site contaminants.
Analytical Information Provided:
The EMS 1 was used to investigate the shallow subsurface, or unsaturated zone since it
has an effective exploration depth of approximately 12 feet using the fixed coil spacing
of 3.7 meters. The EM34 was used to investigate subsequent deeper intervals because
the coil space can be varied and essentially tuned to specific target depths. The survey
used a 10 meter coil spacing to investigate the saturated zone of the site, since the
instrument set in the vertical dipole mode (coils placed horizontally on the ground) has
a peak response from materials from approximately 3 to 7 meters below the ground
surface (10 to 20 feet). The average groundwater depth at the site is approximately 15
feet. A 20 meter coil spacing to investigate possible bedrock features, since in this
configuration, the instrument has a peak response for materials from approximately 6
to 12 meters below the ground surface (20 to 30 feet). Bedrock at the site is up to 21
feet below ground surface (below ground surface (bgs), and possible target features
such as bedrock channeling, may be deeper.
Project Cost and Time Savings
Total Cost (includes grid setup, data collection,
data analysis and report generation):
Total= $3,500
Total Cost Per Sample (includes labor, analysis and
consumables): Approximately $0.23 per EMS 1 reading and
$1.13 per EM34 reading, based on 31 survey lines with 250 (or
50) data points on each line for 7750 (or 1550) measurements.
Instrument Cost:
Rental Costs: $3,500 for 4
days.
Consumables Cost:
Not applicable.
Consumables were
not required.
Labor Cost:
Not applicable
Waste Disposal
Cost:
Waste disposal
costs were not
applicable for this
technology. No
waste was
generated as a
result of the
geophysical
surveys.
Time Savings:
lYear
Site characterization activities using a
dynamic work strategy were completed in
several weeks. Sufficient data to place
monitoring wells and complete the
Targeted Brownfields Assessment (TEA)
were completed in a single funding cycle
(1 year). Site characterization following a
traditional phased approach would have
required multiple mobilizations taking
place over 2 Brownfields funding cycles
(2 years).
Site-Specific Precision and Accuracy Achieved:
Not applicable for this technology
Throughput Achieved:
Survey lines with wood stakes and
flagging spaced 20 feet apart in an area
measuring approximately 500 feet by 600
feet, parallel to the Cache La Poudre
River. Measurements were recorded in a
data logger along the survey lines
approximately every two feet with the
EM31 and every 10 feet with the EM34
for good lateral resolution, giving a
throughput of -500 readings/hr for the
EMS 1 and -100 readings/hr for the EM34
-------
TECHNOLOGY QUICK REFERENCE SHEET #4 (CONTINUED)
GEONICS LIMITED EM31 AND EM34
TERRAIN CONDUCTIVITY METERS
General Commercial Information (Information valid as of September 2003)
Vendor
Contact:
JD McNeill
905-670-9580
Vendor Information:
Geonics Limited
1745 Meyerside Drive, Unit
8
Mississauga, Ontario
Canada
L5T 1C6
Telephone: 905 670 9580
Telefax: 905 670 9204
Limitations on Performance:
Each instrument has limited vertical sounding capabilities. The EMS 1
can effectively map terrain conductivity to about 18 feet below ground
surface (bgs) using a 3.7 meter coil spacing. The EMS4 can be tuned to
specific depths. With an effective total depth of approximately 180 feet
bgs.
Inductive electromagnetic techniques have a limited dynamic range. At
low values of terrain conductivity it becomes increasingly difficult to
magnetically induce a detectable magnetic field at the receiver coil. At
very high values the received magnetic field is no longer linearly
proportional to the terrain conductivity. Setting and maintaining the
instrument zero can be difficult, although over most terrain conductivities
the zero error is negligible. At locations where the instruments are being
used to measure highly resistive ground the zero error can be significant.
Principle of Analytical Operation:
A time varying magnetic field arising from
alternating current in the transmitter coil
induces very small currents in the earth.
These currents generate a secondary
magnetic field that is sensed by the receiver
coil in conjunction with the primary field.
The secondary magnetic field is a
complicated function of intercoil spacing,
the operating frequency, and the ground
conductivity.
Using a complicated formula, the
instrument software generates a ratio of the
secondary current to the primary magnetic
field that is linearly proportional to the
terrain conductivity. This allows the
instruments to be a direct reading linear
terrain conductivity meter simply by
measuring this ratio.
Availability/Rates:
The EM31 and EMS 4 terrain conductivity meters are available through
Geonics Limited. These instruments can also be procured as a service
through various geophysical survey companies.
Power Requirements:
The instruments are field portable and supply their own power via
rechargeable batteries.
Instrument Weight and/or Footprint:
Both the EMS 1 and EM34 weigh less than 30 pounds and are easily
transported into the field. The data loggers are readily removed from the
console for easy data downloading. Additional space may be required for
laptops employing terrain mapping software.
EM 31
EM34
GENERAL PERFORMANCE INFORMATION
Potential interferences include:
Applicable Media/Matrices:
Soil/Groundwater
Wastes Generated Requiring
Special Disposal:
None
Analytes Measurable with
Expected Detection Limits:
Terrain conductivity in
Siemen/meter or
millimho/meter. Results can
also be converted to resistivity
values in ohmmeters.
Dynamic range 1-1,000
millimho/meter
Other General Accuracy/Precision
Information:
Data interpretation is aided through the use of
known geology from boreholes or other
benchmarks.
Rate of Throughput:
Large grid surveys (approximately 750 nodes)
can be completed in 1 day. Additional time is
needed for data interpretation and mapping.
-------
TECHNOLOGY QUICK REFERENCE SHEET #5
ADVANCED GEOSCIENCES INC. (AGI)
SUPERSTING RESISTIVITY CONTROL UNIT
(HIGH RESOLUTION RESISTIVITY GEOPHYSICAL SURVEY)
Summary of Project-Specific Performance Information
Project Role:
Guide dynamic sampling
activities for a Triad
investigation. Provide an
evaluation of shallow
subsurface geology to refine
the conceptual site model.
Results can also be
interpreted to assist in
identification of preferential
contaminant migration
pathways as well as locate
potential site contaminants.
Analytical Information Provided:
High Resolution Resistivity (HRR) was used to characterize shallow bedrock and other
subsurface conditions. Seven survey lines were used to grid the site and a total of
5,110 feet of HRR data was acquired (mostly over unpaved areas) over 9 days. The
HRR survey used the SuperSting resistivity control unit, a battery powered
programmable unit capable of acquiring resistivity and induced polarization
geophysical data. Data collected included bedrock surface and other shallow geologic
information to assist in refinement of the conceptual site model (CSM). Information
correlated extremely well with visually observed drilling cores obtained during the
subsequent limited drilling program. Maps obtained were used to provide site-wide
coverage of the bedrock surface, refine and focus the drilling program, and to evaluate
potential preferential pathways of contaminant migration.
Project Cost and Time Savings
Total Cost (includes grid setup, data collection, data
analysis and report generation):
Total= $24,800
Total Cost Per Sample (includes labor, analysis and
consumables): Not applicable.
Instrument Cost:
Not applicable for this
technology as analyses were
not performed.
Rental Costs: Not applicable
for this project, technology
was procured through a
geophysical vendor.
Consumables Cost:
Not applicable.
Consumables were not
required.
Labor Cost:
Not applicable
Waste Disposal Cost:
Waste disposal costs
were not applicable for
this technology. No
waste was generated as a
result of the geophysical
surveys.
Time Savings:
lYear
Site characterization activities
using a dynamic work strategy
were completed in several
weeks. Sufficient data to place
monitoring wells and complete
the Targeted Brownfields
Assessment (TEA) were
completed in a single funding
cycle (1 year). Site
characterization following a
traditional phased approach
would have required multiple
mobilizations taking place over
2 Brownfields funding cycles
(2 years).
Site-Specific Precision and Accuracy Achieved:
Not applicable for this technology
Throughput Achieved:
5,110 feet of HRR information
was obtained.
Four figures depicting
subsurface geology at the site
were developed and a
comprehensive report was
provided by the vendor.
-------
TECHNOLOGY QUICK REFERENCE SHEET #5 (CONTINUED)
ADVANCED GEOSCIENCES INC. (AGI)
SUPERSTING RESISTIVITY CONTROL UNIT
(HIGH RESOLUTION RESISTIVITY GEOPHYSICAL SURVEY)
General Commercial Information (Information valid as of September 2004)
Vendor Contact:
General Information:
info(@,agiusa.com
Sales info & order:
sales(@,agiusa.com
Customer Support:
support(g),agiusa.com
Vendor Information:
Advanced Geosciences Inc.
12700 Volente Rd.
(FM2769), Bldg. A, Austin,
TX 78726, USA
Telephone: 512-335-3338
Telefax: 512-258-9958
Limitations on Performance:
Electrical resistivity techniques are more labor intensive and
time consuming than ground penetrating radar (GPR)
techniques. The resistivity method is strongly sensitive to
changes in moisture content but can also be affected by
changes in grain size distributions, clay content, and other
geologic properties. Apparent resistivity values are
influenced by the amount of interstitial moisture content and
the type of geologic media.
Principle of Analytical Operation:
The survey consisted of a four-electrode array with
two electrodes forming a transmitting pair or "dipole"
whereby electrical current is injected into the earth.
Two electrodes form a receiving pair, or "dipole", and
measure the voltage difference due to the impressed
current. HRR generally uses a "pole-pole" array
whereby two of the four electrodes are placed at a
predetermined distance away (effectively at an infinite
distance) from the survey area so that they do not
affect survey data, leaving two "active" electrodes for
survey line data acquisition. The "active" electrodes in
a pole-pole array are a single current source electrode
and a nearby potential measuring electrode. The
remote or "infinite" electrode locations normally
remain fixed during surveys unless larger areas are
involved. The two "active" electrodes are arranged
collinearly so that the distances between them vary in
an incremental manner. For conventional shallow
investigations, the distance between the two active
electrodes typically varies between five and 200 feet.
Survey line locations and spacing are determined by
objective, target size, and depth of burial. Since
topography will distort resistivity profiles, changes in
elevation along the geophysical lines are surveyed to
be used for subsequent data processing. Recorded
apparent resistivity data can be processed and inverted
using software that allows topographic correction and
provides robust depth estimates. The resulting image
is a contoured section.
Availability/Rates:
The AGI Supersting resistivity control unit is available
through Advanced Geosciences Inc. (AGI). These
instruments can also be procured as a service through
various geophysical survey companies.
Power Requirements:
The instruments are field portable and supply their own
power via 12V or 2xl2V DC external batteries.
Instrument Weight and/or Footprint:
The SuperSting Rl IP (instrument only) weighs 10.9 kg (24
Ib). Width 184 mm (7.25"), length 406 mm (16") and height
273 mm (10.75").
-------
TECHNOLOGY QUICK REFERENCE SHEET #5 (CONTINUED)
Advanced Geosciences Inc. (AGI)
SUPERSTING RESISTIVITY CONTROL UNIT
(HIGH RESOLUTION RESISTIVITY GEOPHYSICAL SURVEY)
GENERAL PERFORMANCE INFORMATION
Potential interferences include: Overhead and buried utilities.
Applicable Media/Matrices:
Soil/Groundwater
Wastes Generated Requiring
Special Disposal:
None
Analytes Measurable with Expected
Detection Limits:
Measurement modes: Apparent
resistivity, resistance, self potential
(SP), induced polarization (IP), battery
voltage
Measurement range: +/- lOVMeasuring
resolution: Max 30 nV, depends on
voltage level
Screen resolution: 4 digits in
engineering notation.
Other General Accuracy/Precision
Information:
Data interpretation is aided through the
use of known geology from boreholes
or other benchmarks.
Rate of Throughput:
Large line surveys can be completed in
1 day. Additional time is needed for
data interpretation and mapping.
-------
APPENDIX 2
MANUFACTURED GAS PLANT COAL TAR FINGERPRINTING USING POLYNUCLEAR
AROMATIC HYDROCARBONS
-------
-2
Correlations of PAH Concentrations in fig/kg
Normalized to Benzo (A) Pyrene
Cache La Poudre River Samples vs. Sample BTH-10 (5-15')
Scatterplot: FC-PR-01 vs. BTH-10 (5-15')
Results Normalized to Benzo (A) Pyrene
BTH-10 (5-15') = .61469 + .55E-3 * FC-PR-01
Correlation: r = .00641
Scatterplot: FC-PS-01 vs. BTH-10 (5-15')
Results Normalized to Benzo (A) Pyrene
BTH-10 (5-15') = .62483 - .0022 * FC-PS-01
Correlation: r = -.0206
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Concentration of PAHs in ug/kg
for Sample FC-PR-01
Results Normalized to Benzo (A) Pyrene | ^a^gsyo confidence |
Scatterplot: PRSB-8DL vs. BTH-10 (5-15')
Results Normalized to Benzo (A) Pyrene
BTH-10 (5-15') NormBAP = .64883 - .0071 * PRSB-8DL NormBAP
Correlations = -.1035
Concentration of PAHs in ug/kg
for Sample FC-PS-01
Results Normalized to Benzo (A) Pyrene
Scatterplot: TR01SP DL vs. BTH-10 (5-15')
Results Normalized to Benzo (A) Pyrene
BTH-10 (5-15') = .63915 - .0049 *TR01SPDL
Correlation: r = -.0690
% confidence |
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Concentation of PAHs in ug/kg
for Sample PRSB-8DL
Results Normalized to Benzo (A) Pyrene | >«V95% confidence
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Concentration of PAHs in ug/kg
for Sample TR01SP DL
Results Normalized to Benzo (A) Pyrene | V«kx95% confidenc
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Correlations of PAH Concentations in fig/kg
Normalized to Benzo (A) Pyrene
Cache La Poudre River Samples vs. Sample H1250
Scatterplot: FC-PR-01 vs. H1250
Results Normalized to Benzo (A) Pyrene
H1250 = 1.4345 + .06906 * FC-PR-01
Correlation: r = .23327
Scatterplot: FC-PS-01 vs. H1250
Results Normalized to Benzo (A) Pyrene
H1250 = 1.3724 + .09104 * FC-PS-01
Correlation: r = .24626
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Concentrations of PAFIs in ug/kg
for Sample FC-PR-01
Results Normalized to Benzo (A) Pyrene
Scatterplot: PRSB-8DL vs. H1250
Results Normalized to Benzo (A) Pyrene
H1250 = 1.5729 + .02889 * PRSB-8DL
Correlation: r = . 12204
16
18
20
22
-2
| ~X.95% confidence |
4 6 8 10 12
Concentration of PAFIs in ug/kg
for Sample FC-PS-01
Results Normalized to Benzo (A) Pyrene
Scatterplot: TR01SP DL vs. H1250
Results Normalized to Benzo (A) Pyrene
H1250 = 1.5711 + .02938 * TR01SP DL
Correlation: r = . 11809
14 16 18
^ 95% confidence
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Concentration of PAHs in ug/kg
for Sample PRSB-8DL
Results Normalized to Benzo (A) Pyrene ^«^95% confidence
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14
16 18 20 22 24 26
Concentration of PAFIs in ug/kg
for Sample TR01SPDL
Results Normalized to Benzo (A) Pyrene
| ^«^ 95% confidence
-------
Correlations of PAH Concentrations in fig/kg
Normalized to Benzo (A) Pyrene
Cache La Poudre River Samples vs. Sample TP-2 11.5'
Scatterplot: FC-PR-01 vs. TP-2, 11.5'
Results Normalized to Benzo (A) Pyrene
TP-2, 11.5' = -168.4 + 157.56 * FC-PR-01
Correlation: r = .97603
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Concentrations of PAHs in ug/kg
for Sample FC-PR-01
Results Normalized to Benzo (A) Pyrene
Scatterplot: PRSB-8DL vs. TP-2, 11.5'
Results Normalized to Benzo (A) Pyrene
TP-2, 11.5' = -104.1 + 121.29 * PRSB-8DL
Correlation: r = .93976
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Scatterplot: FC-PS-01 vs. TP-2, 11.5'
Results Normalized to Benzo (A) Pyrene
TP-2, 11.5' = -253.1 + 192.05 * FC-PS-01
Correlation: r = .95265
3500
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2400
2200
2000
1800
1600
1400
1200
1000
800
600
400
200
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Bar/Column Plot for Sample BTH-10 (5-15')
PAH Concentrations in J-ig/kg
m
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2.8E5
2.6E5
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2.2E5
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1.8E5
1.6E5
1.4E5
1.2E5
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80000
60000
40000
20000
PAH Ratios for Cache La Poudre
River Samples vs. Sample BTH-10 (5-15')
Bar/Column Plot for Sample FC-PR-01
PAH Concentrations in J-ig/kg
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1.2E7
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Bar/Column Plot for Sample FC-PS-01
PAH Concentrations in J-ig/kg
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Bar/Column Plot for Sample PRSB-8DL
PAH Concentrations in J-ig/kg
40000
35000
30000
25000
20000
15000
10000
5000
Bar/Column Plot for Sample TR01SP
PAH Concentrations in J-ig/kg
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Bar/Column Plot for Sample HI 250
PAH Concentrations in j-ig/kg
PAH Ratios for Cach La Poudre
River Samples vs. Sample H1250
Bar/Column Plot for Sample FC-PR-01
PAH Concentrations in j-ig/kg
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16000
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6000
4000
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PAH Concentrations in j-ig/kg
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Bar/Column Plot for Sample PRSB-8DL
PAH Concentrations m J-ig/kg
40000
35000
Bar/Column Plot for Sample TR01SP
PAH Concentrations in J^g/kg
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Bar/Column Plot for Sample TP-2, 11.5'
PAH Concentrations in j-ig/kg
PAH Ratios for Cache La Poudre
River Samples vs.Sample TP-2,11.5'
Bar/Column Plot for Sample FC-PR-01
PAH Concentrations in J^g/kg
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2.6E5
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Bar/Column Plot for Sample FC-PS-01
PAH Concentrations in J^g/kg
1.4E7
1.2E7
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6E6
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2.2E8
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Bar/Column Plot for Sample PRSB-8DL
PAH Concentrations in J-ig/kg
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35000
30000
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10000
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Bar/Column Plot for Sample TR01SP
PAH Concentrations m J^g/kg
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