EPA542-R-14-010
Office of Solid Waste and Emergency Response
U nited States Office of Superfund Remediation and
Environmental Protection Technology Innovation
Agency
Optimization Review
Lockwood Operable Unit 2 -
Soco/Brenntag Source Area
Billings, Montana
www.clu-in.org/optimization lwww.epa.gov/superfund/cleanup/postconstruction/optimize.htm
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OPTIMIZATION REVIEW
LOCKWOOD OPERABLE UNIT 2 - SOCO/BRENNTAG SOURCE AREA
BILLINGS, MONTANA
Report of the Optimization Review
Conducted at Lockwood Solvent Groundwater Plume Site
FINAL REPORT
September 19, 2014
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EXECUTIVE SUMMARY
Optimization Background
The U.S. Environmental Protection Agency (EPA) defines optimization as the following:
"Efforts at any phase of the removal or remedial response to identify and implement specific
actions that improve the effectiveness and cost-efficiency of that phase. Such actions may also
improve the remedy's protectiveness and long-term implementation which may facilitate progress
towards site completion. To identify these opportunities, regions may use a systematic site review
by a team of independent technical experts, apply techniques or principles from Green
Remediation or Triad, or apply other approaches to identify opportunities for greater efficiency
and effectiveness. Contractors, states, tribes, the public, and PRPs [potentially responsible
parties] are also encouraged to put forth opportunities for the Agency to consider. "
An optimization review considers the goals of the remedy, available site data, the conceptual site model
(CSM), remedy performance, protectiveness, cost-effectiveness and the closure strategy. A strong interest
in sustainability has also developed in the private sector and within federal, state, and municipal
governments. Consistent with this interest, optimization now routinely considers green remediation and
environmental footprint reduction during optimization reviews.
An optimization review includes reviewing site documents, interviewing site stakeholders, potentially
visiting the site for 1 day, and compiling a report that includes recommendations in the following
categories:
Protectiveness
Cost-effectiveness
Technical improvement
Site completion
Environmental footprint reduction
The recommendations are intended to help the site team identify opportunities for improvements in these
areas. In many cases, further analysis of a recommendation, beyond that provided in this report, may be
needed before the recommendation can be implemented. Note that the recommendations are based on an
independent review and represent the opinions of the optimization review team. These recommendations
do not constitute requirements for future action, but rather are provided for consideration by the State of
Montana, the Region, and other site stakeholders. Also note that while the recommendations may provide
some details to consider during implementation, the recommendations are not meant to replace other,
more comprehensive, planning documents such as work plans, sampling plans, and quality assurance
project plans (QAPP).
Site-Specific Background
The Lockwood Solvent Groundwater Plume Site (LSGPS) is located on the outskirts of Billings,
Montana, in EPA Region 8. The site is managed as two operable units (OUs). OU1 consists of
U.S. Environmental Protection Agency (EPA). 2012. Memorandum: Transmittal of the National Strategy to Expand
Superfund Optimization Practices from Site Assessment to Site Completion. From: James. E. Woolford, Director Office of
Superfund Remediation and Technology Innovation. To: Superfund National Policy Managers (Regions 1 - 10). Office of
Solid Waste and Emergency Response (OSWER) 9200.3-75. September 28.
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contaminated soils and a plume of chlorinated solvents in groundwater associated with the Beall Source
Area (Area B), and OU2 consists of affected media associated with the Brenntag (Soco; Area A) Source
Area. This optimization review addressed remedial components planned for affected soil and groundwater
in OU2. OU1 is addressed under a separate optimization review report.
The source area for OU2 is a former chemical storage, re-packaging, and distribution facility operated
under the Brenntag and Dyce Chemical corporate names. The facility began operations in 1972. The
property is currently under new ownership, with no on-going commercial activity. Built structures have
been demolished. Remediation of affected soil and groundwater is currently being conducted under the
Superfund program as a PRP-lead project.
In 1986, Lockwood Water and Sewer District (LWSD) personnel identified benzene and chlorinated
solvents in Lockwood area water supply wells, leading to a number of investigations by the Montana
Department of Environmental Quality (DEQ). In June 1998, DEQ performed an integrated site
assessment in cooperation with the EPA. The LSGPS was added to the National Priorities List (NPL) in
2000 (CERCLIS ID# MT0007623052).
In 2002, the DEQ conducted a Remedial Investigation (RI) that included surface and subsurface soil
sampling, monitoring well construction and groundwater sampling, aquifer testing, surface water
sampling, sediment sampling and soil vapor sampling. Based on the RI results, the EPA and DEQ
evaluated remedial alternatives as part of a Feasibility Study (FS) and Proposed Plan completed in July
2004. The site-wide LSGPS Record of Decision (ROD) was issued in 2005. The 2005 ROD selected the
following components for the OU2 remedial action:
Soil excavation of accessible vadose zone soils in the source area
Ex situ thermal treatment of excavated soils
Soil vapor extraction (SVE)/ozone sparging of inaccessible vadose zone soils in the source area
In situ chemical oxidation (ISCO) of inaccessbible saturated zone soils
In situ bioremediation (ISB) treatment of groundwater source and plume
Permeable reactive barrier (PRB) of source groundwater
Risk mitigation for groundwater and subsurface soils including monitoring potable water
supplies, mitigation (providing municipal water) for affected private water supply wells, and
indoor air monitoring and mitigation as needed
Institutional controls to prohibit excavation and drilling in affected subsurface areas
Groundwater monitoring of the alluvial aquifer
Five-year reviews.
The remedial design (RD) process is under way at OU2, with the goal of addressing contamination
associated with the Soco Source Area.
The LSGPS was nominated for an optimization review by the EPA Office of Superfund Remediation and
Technology Innovation (OSRTI) at the request of the Region 8 Remedial Project Manager (RPM) in
September 2012. The review of remedy design considerations for the selected remedy options for the
LSGPS OU2 is intended to optimize the remedial response to address contamination in soil and
groundwater, to achieve maximum protectiveness while improving remedy cost and energy efficiency and
to minimize time required to achieve cleanup goals.
Summary of Conceptual Site Model and Key Findings
Several primary sources of contamination have been identified within the former chemical handling
facility at OU2. Site data suggest that contamination was released at different times and by different
mechanisms at several locations around the facility. The priority contaminant of concern (COC) and
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parent constituent on site is tetrachloroethene (PCE), but several other hydrocarbon compounds are also
present in shallow soils. PCE in the shallow subsurface has undergone anaerobic degradation, resulting in
formation of the decay products, trichloroethene (TCE), cis-l,2-dichloroethene (cis-l,2-DCE), and vinyl
chloride. PCE and its degradation products have been detected at concentrations above EPA Maximum
Contaminant Levels (MCLs) in groundwater.
Site surface soil and shallow subsurface soils are composed of highly heterogeneous, interbedded sands
and gravels, silty sands, clays and silts. PCE and other chlorinated volatile organic compounds (cVOCs)
released from the diverse primary sources have migrated to the saturated zone (located at approximately
10 feet below ground surface). Source area soils show both vertical and horizontal heterogeneity and
discontinuous concentrations of the primary COCs. The distributed nature of source materials and
contamination adds complexity to selecting effective remedial approaches. High concentrations of cVOCs
in soils imply the presence of non-aqueous phase liquids (NAPL). Because of the heterogeneity of soil
textures, the majority of the contamination that remains is likely present in the relatively impermeable silt
layers, possibly serving as a long-term secondary source of contamination.
A saturated silt, sand and gravel shallow alluvial aquifer is present between 15 and 30 feet below ground
surface. A sandstone and shale bedrock layer (Eagle Sandstone) lies below 30 feet depth. Groundwater in
the bedrock aquifer does not appear to be contaminated. A groundwater plume in the shallow alluvial
aquifer extends to the northwest from the OU2 source area, ultimately discharging to the Yellowstone
River approximately 2,000 feet downgradient of the OU2 source area. Centerline concentrations of PCE
in the alluvial plume are in the range of 300 to 2,000 micrograms per liter ((ig/L). Groundwater flow
direction is to the north-northwest with relatively flat gradients. Historical activities in the flood plain,
such as dewatering in the gravel pit north of the source area may have influenced the shape of the
contaminant plume.
Historical water supply wells may have pulled contaminated groundwater to the west. Shallow supply
wells in the area have been abandoned and area residents supplied with municipal water. The change in
pumping regime may cause the plume to migrate more toward the north/northeast in the future.
The average saturated thickness in the shallow aquifer is about 20 feet. Groundwater seepage velocities
are in the range of 2.75 feet per year (for low permeability saturated zones) to 654 feet per year (in the
saturated gravel zones). The precise distribution of contamination in the saturated zone is currently
difficult to quantify because well screens at many locations are 20 feet long.
The highest dissolved contaminant concentrations in groundwater were detected at wells installed to
monitor the Northwest Source Area and the pilot-scale SVE/ozone sparging system. Wells in this area
show stable to decreasing concentration trends for PCE by the Mann-Kendall statistical test for trend,
indicating that the SVE/ozone sparging system tested in the area was effective at removing contaminant
mass.
Potentially complete exposure pathways associated with OU2 include ingestion of, and direct contact
with, contaminated groundwater, and vapor intrusion in nearby residences and commercial operations and
on-site exposure to contaminated soils. Shallow, private water supply wells in the area have been
abandoned and area residents have been supplied with municipal water. Residential indoor air sampling
was conducted in 1999 and 2000 by the Superfund Technical Assessment and Response Team (START)
to evaluate health risks from vapor intrusion of chlorinated solvents into area residences. Mitigation of
risks related to contaminated groundwater and indoor air exposure are on-going. Plume discharge to the
Yellowstone River is not considered to cause excess ecological risk.
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Summary of Recommendations
Optimization review team recommendations were developed to support an adaptive management strategy
for long-term remediation of soil and groundwater at OU2. The following sequence of activities is
recommended to optimize the RD process and long-term remedy performance at LSGPS OU2:
Additional groundwater wells are recommended for the source and immediate downgradient
plume. Wells are recommended to be installed in clusters of three depths using Rotosonic drilling
and 5-foot screened intervals. (Note: this recommendation has largely been accomplished.)
Perform depth-discreet groundwater sampling to identify the intervals of highest contamination at
sampling locations with long screens in the downgradient plume. Identifying the areas of highest
contamination will support locating remedies for optimal mass removal.
Use existing data to prepare highly detailed, OU2-specific cross sections that highlight low-
permeability seams and areas of highest contaminant mass. Use detailed source-area data to refine
theRD.
Reactivate and expand the SVE/ozone sparging remedy for the Northwest Source Area and other
nearby highly contaminated primary source areas. Expand the ex situ SVE/ozone sparging system
to treat excavated soils.
Excavate and treat highly contaminated, low-permeability, shallow soil (above 20 feet below
ground surface) with ex situ SVE/ozone sparging. The time and efficacy benefit of excavation
may outweigh the added cost of excavation. On-site treatment with the SVE/ozone sparging
system already in place will reduce costs and improve efficiency.
Implement ISB treatment in the source area. Placement of the ISB remedy should be based on the
interpretation of data from the additional site characterization recommended above. Add the ISB
amendment at the base of the excavations (if implemented) to treat deeper areas of contamination
at and below the water table in the source area.
Conduct performance monitoring for the source remedy for 3 to 5 years after implementation.
Prioritize source area remediation. Delay implementation of an ISB remedy in the dissolved
leading edge of the groundwater plume until 3 to 5 years of source area remedy performance data
have been collected and analyzed. Given the high rate of groundwater flow, the success of the
source remedy should be apparent in downgradient alluvial aquifer wells (for example, MW-007,
MW-122, and MW-009) relatively rapidly. Strongly decreasing concentration trends and a
reduced or altered plume footprint in response to source treatment may influence the location and
extent of the downgradient ISB plume remedy.
Carefully monitor the northern and eastern edges of the plume near well MW-006, where
concentrations may be increasing because groundwater flow is no longer influenced by pumping
from historical operations at the gravel pit. If concentrations increase above MCLs at well MW-
006, consider installing an additional monitoring well to delineate the plume to the northeast.
Improving effectiveness -
Recommendations to improve remedy effectiveness include addressing data gaps through additional site
characterization. Data acquired from additional sampling can be used to scale and position remedial
components for maximum efficacy. Remedy effectiveness should be improved through adaptive site
management following the sequence of activities outlined above. The optimization review team
recommends a combination of expanded SVE/ozone sparging, excavation and ex situ soil treatment with
ex situ SVE/ozone sparging, followed by ISB for source area contamination. Targeted excavation of
highly contaminated, low-permeability soils followed by ex situ SVE/ozone sparging treatment on site
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should reduce the potential for long-term back diffusion. ISB treatment at the base of the excavations will
stimulate anaerobic degradation of the residual cVOC constituents.
Reducing cost -
No specific recommendations are provided in this category at this time. The adaptive site management
approach, where decisions are made based on the data gathered during implementation of the
optimization recommendations, should provide long-term reduction in cost. Expanding the existing
SVE/ozone sparging system to treat shallow contamination and excavated soils should be cost efficient
relative to other potential remedies considered.
Delaying the decision on the scale or necessity of ISB treatment for the downgradient plume may result in
long-term cost savings by scaling and positioning the ISB remedy for maximum efficacy.
Technical improvement -
Recommendations for technical improvement are the largely same as those for improved efficacy.
Additional site characterization and sequencing of remedial approaches should improve the performance
of selected remedies. Specific recommendations for remedy performance monitoring will indicate when
remedies are not functioning as anticipated. Underperforming remedies can be modified or terminated,
based on accumulated data.
Site closure -
Specific recommendations are provided for short- and long-term remedy performance monitoring.
Acquisition of statistically significant datasets to evaluate remedy performance will support decisions on
termination of active remedies and site redevelopment.
Green remediation -
Addressing data gaps through further source characterization should support the design of more efficient
remedy scale and placement, thus reducing the overall footprint of the remedy. Expanding the existing
pilot-scale SVE/ozone sparging system to treat excavated soils should reduce the carbon footprint of the
overall remedy, especially compared with the thermal treatment option considered.
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NOTICE AND DISCLAIMER
Work described herein was performed by Tetra Tech, Inc. (Tetra Tech) for the U.S. Environmental
Protection Agency (EPA). GSI Environmental performed work under a subcontract to Tetra Tech. Work
conducted by Tetra Tech, including preparation of this report, was performed under Work Assignment 2-
58 of EPA contract EP-W-07-078 with Tetra Tech. The report was approved for release as an EPA
document, following the Agency's administrative and expert review process.
This optimization review is an independent study funded by the EPA that focuses on protectiveness, cost-
effectiveness, site closure, technical improvements and green remediation. Detailed consideration of EPA
policy was not part of the scope of work for this review. This report does not impose legally binding
requirements, confer legal rights, impose legal obligations, implement any statutory or regulatory
provisions or change or substitute for any statutory or regulatory provisions. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
Recommendations are based on an independent evaluation of existing site information, represent the
technical views of the optimization review team and are intended to help the site team identify
opportunities for improvements in the current site remediation strategy. These recommendations do not
constitute requirements for future action; rather, they are provided for consideration by the State of
Montana, EPA Region and other site stakeholders.
While certain recommendations may provide specific details to consider during implementation, these
recommendations are not meant to supersede other, more comprehensive, planning documents such as
work plans, sampling plans and quality assurance project plans (QAPP); nor are they intended to override
applicable or relevant and appropriate requirements (ARARs). Further analysis of recommendations,
including review of EPA policy may be needed prior to implementation.
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PREFACE
This report was prepared as part of a national strategy to expand Superfund optimization from remedial
investigation to site completion implemented by the U.S. Environmental Protection Agency (EPA) Office
of Superfund Remediation and Technology Innovation (OSRTI)^. The project contacts are as follows:
Organization
Key Contact
Contact Information
U.S. Environmental
Protection Agency (EPA)
Office of Superfund
Remediation and Technology
Innovation
(OSRTI)
Kirby Biggs
EPA OSRTI
Technology Innovation and Field Services
Division (TIFSD)
2777 Crystal Drive
Arlington, VA 22202
biggs.kirby@epa.gov
phone: 703-823-3081
Tetra Tech
(Contractor to EPA)
Jody Edwards, P.G.
Tetra Tech, Inc.
45610 Woodland Road
Suite 400
Sterling, VA 20166
jody.edwards@tetratech.com
phone: 802-288-9485
GSI Environmental
(Contractor to EPA)
Mindy Vanderford, Ph.D.
GSI Environmental, Inc.
2211 Norfolk
Suite 1000
Houston, TX 77098
mvanderford@gsi-net.com
phone: 713-522-6300x186
2 U.S. Environmental Protection Agency (EPA). 2012. Memorandum: Transmittal of the National Strategy to Expand
Superfund Optimization Practices from Site Assessment to Site Completion. From: James. E. Woolford, Director Office of
Superfund Remediation and Technology Innovation. To: Superfund National Policy Managers (Regions 1 - 10). Office of
Solid Waste and Emergency Response (OSWER) 9200.3-75. September 28.
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LIST OF ACRONYMS AND ABBREVIATIONS
(ig/kg Micrograms per Kilogram
(ig/L Micrograms per Liter
ATC Advanced Technologies, Inc.
bgs Below Ground Surface
BTEX Benzene, Toluene, Ethylbenzene and Xylene
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
cis-1,2-DCE cis-1,2-Dichloroethene
COC Contaminant of Concern
CSM Conceptual Site Model
cVOC Chlorinated Volatile Organic Compound
cy Cubic yards
DEQ Department of Environmental Quality
EPA U.S. Environmental Protection Agency
FS Feasibility Study
FYR Five-Year Review
GAC Granular Activated Carbon
GIS Geographic Information System
ISB In situ Bioremediation
1C Institutional Control
ISCO In situ Chemical Oxidation
LSGPS Lockwood Solvent Groundwater Plume Site
LWSD Lockwood Water and Sewer District
MAROS Monitoring and Remediation Optimization System Software
MCL Maximum Contaminant Level
mg/kg Milligrams per Kilogram
MW Monitoring Well
N/A Not Applicable
NAPL Non-Aqueous Phase Liquid
NI Not Identified
NPL National Priorities List
OSRTI Office of Superfund Remediation and Technology Innovation
OSWER Office of Solid Waste and Emergency Response
OU Operable Unit
OU2 Operable Unit 2, Soco West source area (formerly known as Brenntag)
PCE Tetrachloroethene
PDB Permeable diffusion bag
PRB Permeable Reactive Barrier
PRP Potentially Responsible Party
PWT Pacific Western Technologies, Ltd.
QAPP Quality Assurance Project Plan
RAC Remedial Action Contractor
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RACER Remedial Action Cost Engineering and Requirements System
RAO Remedial Action Objective
RD Remedial Design
RI Remedial Investigation
ROD Record of Decision
RPM Remedial Project Manager
START Superfund Technical Assessment and Response Team
SVE Soil Vapor Extraction
TCE Trichloroethene
VOC Volatile Organic Compound
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TABLE OF CONTENTS
EXECUTIVE SUMMARY ES-1
NOTICE AND DISCLAIMER i
PREFACE ii
LIST OF ACRONYMS AND ABBREVIATIONS iii
1.0 OBJECTIVES OF OPTIMIZATION REVIEW 1
1.1 Objectives of the Remedial Design Optimization 1
1.2 Team Composition 2
1.3 Documents and Data Reviewed 3
1.4 Quality Assurance 4
2.0 CONCEPTUAL SITE MODEL 5
2.1 Site Background 5
2.2 Source Areas 5
2.3 Surface Water, Soils and the Unsaturated Subsurface 7
2.4 Groundwater 7
3.0 REMEDIAL ACTION OBJECTIVES AND SELECTED REMEDY OPTIONS 10
3.1 Remedial Action Objectives and Affected Media 10
3.2 Selected Remedy Options 11
4.0 FINDINGS 13
4.1 CSM Implications for Remedial Strategy 13
4.2 Data Gaps 14
4.3 Considerations forthe Remedial Strategy 14
5.0 RECOMMENDATIONS 18
5.1 Recommendations to Sequence Remedial Approach 18
5.2 Recommendations to Characterize the Source Area for Remedy Design Refinement 19
5.3 Recommendations for Source Area Soil Remediation 21
5.4 Recommendations for Groundwater Remediation 22
5.5 Recommendations for Remedial Performance Monitoring 23
5.6 Recommendations Related to Green Remediation 24
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List of Figures
1 Lockwood Solvent Groundwater Plume Site
2 OU2 Groundwater Plume
3 OU2 Concentration Trends
List of Tables
1 Optimization Review Team
2 Site Visit and Review Participants
3 Contaminants of Concern and Cleanup Levels
4 Affected or Potentially Affected Media on Site
5 Remedy Options Selected in the ROD
6 Identified Data Gaps
7 Cost Estimates for Remedial Alternatives
8 Recommendations Summary
9 Recommended Groundwater Performance Monitoring Program LSGPS OU2
Attachments
ATTACHMENT A: FIGURES EXCERPTED FROM SITE DOCUMENTS
ATTACHMENT B: INTERIM OPTIMIZATION MEMORANDUM AND PRESENTATION
ATTACHMENT C: MONITORING AND REMEDIATION OPTIMIZATION SYSTEM REPORTS
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1.0 OBJECTIVES OF OPTIMIZATION REVIEW
This section describes the objectives of the optimization review, composition of the optimization review
team, documents and data reviewed, and quality assurance.
1.1 Objectives of the Remedial Design Optimization
The Lockwood Solvent Groundwater Plume Site (LSGPS) occupies approximately 580 acres on the
outskirts of Billings, Montana, in U.S. Environmental Protection Agency (EPA) Region 8. The site is
managed as two operable units (OUs). OU1 consists of contaminated soils and the plume of chlorinated
solvents in groundwater associated with the Beall Source Area (Area B). OU2 consists of affected media
associated with the Brenntag (Soco; Area A) Source Area. Additional land is included in the greater
LSGPS (Area C, see Figure 1 below or Attachment A for a full size version), but this area contains no
known primary sources of contamination and low-to non-detectable levels of contaminants.
This optimization review addresses remedial components planned for affected soil and groundwater in
OU2. The remedial design (RD) for OU1 is addressed under a separate optimization report.
Figure 1: Lockwood Solvent Groundwater Plume Site
Source: Figure 10 from OU1 ROD; EPA 2005.
For more than a decade, the EPA Office of Superfund Remediation and Technology Innovation (OSRTI)
has provided technical support to the EPA regional offices through the use of independent (third-party)
optimization reviews at Superfund sites. The LSGPS was nominated for an optimization review at the
request of the Region 8 Remedial Project Manager (RPM) in September 2012. This review of the remedy
design proposed for LSGPS OU2 is intended to optimize the remedial response to address contamination
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Optimization Review Report
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in soil and groundwater to achieve maximum protectiveness while improving remedy cost and energy
efficiency and minimizing time required to meet cleanup goals.
An optimization review team (described below) was assembled and met with regulatory stakeholders and
consultants in Billings, Montana, and at the site in February 2013 to review site data, remediation goals,
logistics and time frames to implement the remedy. This report presents the findings and
recommendations for OU2 based on a review of site documents, the site visit and meetings with
stakeholders.
Objectives of the RD optimization review team included:
Review of the conceptual site model (CSM)
Review of Remedial Action Objectives (RAOs)
Review of selected remedy options and associated costs
Recommendations for remedial strategy, including:
o Addressing and prioritizing significant data gaps in the CSM
o Recommending remedy improvements
o Prioritizing and sequencing remedial components
o Identifying decision points for contingent responses
o Performance monitoring for recommended remedies
o Remediation and data collection to support an exit strategy.
The recommendations are intended to help the site team identify opportunities for improvements in these
areas. In many cases, further analysis of a recommendation, beyond that provided in this report, may be
needed before the recommendation can be implemented. Note that the recommendations are based on an
independent evaluation and represent the opinions of the optimization review team. These
recommendations do not constitute requirements for future action, but rather are provided for
consideration by the State of Montana, the Region and other site stakeholders. Also note that while the
recommendations may provide some details to consider during implementation, the recommendations are
not meant to replace other, more comprehensive, planning documents such as work plans, sampling plans
and quality assurance project plans (QAPP).
The National Optimization Strategy includes a system for tracking consideration and implementation of
the optimization review recommendations. It includes a provision for follow-up technical assistance from
the optimization review team as mutually agreed on by the site management team and EPA OSRTI.
1.2 Team Composition
The LSGPS optimization review team included the following individuals:
Table 1: Optimization Review Team
Name
Doug Sutton
Mindy Vanderford
Affiliation
Tetra Tech
GSI Environmental, Inc.
Phone
713-522-6300
Email
mvanderford@gsi-net.com
In addition to the optimization review team listed above, the individuals listed below also attended the site
visit or contributed to the site data review process:
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Table 2: Site Visit and Review Participants
Name
Kirby Biggs
Tillman McAdams
Andrew Schmidt
John Podolinsky
Catherine LeCours
Roger Hoogerheide
Jim Sullivan
Affiliation
EPA OSRTI
EPA Region 8
EPA Region 8
Montana Department of
Environmental Quality
Pacific Western
Technologies, Inc.
EPA Region 8
Cardno Advanced
Technologies, Inc.
Title or Role
Optimization Review Lead
RPMforOUl
Hydrologist, Technical
Support
State lead for OU2
RAC Contractor for OU2
RPM for OU2
PRP Contractor for OU2
Email Address
biggs.kirbv(@,epa.gov
Hoogerheide.Rogertgiepamail.
epa.gov
Notes: EPA OSRTI = U.S. Environmental Agency Office of Superfund Remediation Technology Innovation; RPM = Remedial
Project Manager; OU = Operable Unit; RAC = Remedial Action Contractor; PRP = potentially responsible party.
Email contact information is provided for the site managers only. Communication with other participants
can be coordinated through the site managers.
The site visit including the individuals listed in Tables 1 and 2 was conducted on February 28, 2013.
1.3 Documents and Data Reviewed
The following documents were reviewed to support the optimization review.
ATC, (2003). Ozone Sparging/Soil Vapor Extraction Pilot Test Report Brenntag West, Advanced
Technologies, Inc. for the Brown Law Firm.
ATC (2005). Soil Vapor Extraction Interim Pilot Test Report. Billings, MT, Prepared for Brenntag West,
Inc. by ATC Associates.
ATC (2012). Remedial Design Assessment Quality Asssurance Project Plan Operable Unit 2; Lockwood
Solvent Groundwater Plume Site. Billings, MT, ATC Associates. Prepared for EPA Region 8 and
Montana Department of Environmental Quality.
ATC (2012). Remedial Design Assessment Work Plan Sampling and Analysis Plan and Field Sampling
Plan Operable Unit 2 Lockwood Solvent Groundwater Plume Site. Billings, MT, ATC Associates
Prepared for US EPA Region 8 and Montana Department of Environmental Quality.
CardnoATC (2012a). Monthly Progress Report #5 - October 2012 Operable Unit 2 Lockwood Solvent
Groundwater Plume Site. Billings, Montana, Prepared for the EPA Region 8, Montana
Department of Environmental Quality.
Cardno ATC (2012b). Monthly Progress Report #6 - November 2012 Operable Unit 2 Lockwood Solvent
Groundwater Plume Site. Billings, Montana, Prepared for the EPA Region 8, Montana
Department of Environmental Quality.
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Cardno ATC (2012c). Vapor Intrusion Assessment Work Plan Operable Unit 2 Lockwood Solvent
Groundwater Plume Site Billings, MT. Billings, MT, Prepared for EPA Region 8 and Montana
Department of Environmental Quality Remediation Division by Cardno ATC.
Department of Justice (2011). Remedial Design/ Remedial Action Consent Decree. Case l:22-cv-00088-
RFC. E. E. S. U.S. Department of Justice. U.S. District Court, District of Montana, Billings, MT.
MSE-HKM (1998). Final Billings Lockwood Pumping Test and Groundwater Monitoring Report.
Helena, MT. Prepared for Montana Department of Environmental Quality.
Tetra Tech (2003). Remedial Investigation Report: Lockwood Solvent Groundwater Plume Site. Helena,
MT. Prepared for Montana Department of Environmental Quality Remediation Division.
Tetra Tech (2004). Final Feasibility Study Report: Lockwood Solvent Groundwater Plume Site. Helena,
MT. Prepared for Montana Department of Environmental Quality.
EPA (2005). Record of Decision: Lockwood Solvent Ground Water Plume OU1. Billings, MT.
Environmental Protection Agency Region 8.
Site soil and groundwater monitoring data, lithologic data, and Geographic Information System (GIS)
files were received from the site contractor (Cardno Advanced Technologies, Inc. [ATC] and Pacific
Western Technologies, Ltd. [PWT]), January 2013.
1.4 Quality Assurance
The optimization review team reviewed existing environmental data to interpret the CSM, evaluate
potential remedy performance and make recommendations to improve the remedy. The quality of existing
data was evaluated by the optimization review team before the data were used for these purposes. The
evaluation for data quality included a brief review of how the data were collected and managed (where
practical, the site QAPP is considered), the consistency of the data with other site data, and the use of the
data in the optimization review. Data that were of suspect quality were either not used as part of the
optimization review or were used with the quality concerns noted. Where appropriate, this report provides
recommendations to improve data quality.
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2.0 CONCEPTUAL SITE MODEL
This section presents information on the site background, source areas, and the surface water, soil,
subsurface unsaturated soil and groundwater media.
2.1 Site Background
The source area for OU2 is a former chemical storage, re-packaging and distribution facility operated
under the Brenntag and Dyce Chemical corporate names. The facility began operations in 1972. The
property is currently under new ownership, with no on-going commercial activity. Built structures have
been largely demolished. Remediation of affected soil and groundwater is currently being conducted
under the Superfund program as a Potentially Responsible Party (PRP)-lead project.
In 1986, Lockwood Water and Sewer District (LWSD) personnel identified benzene and chlorinated
solvents in Lockwood area water supply wells, leading to a number of investigations by the Montana
Department of Environmental Quality (DEQ). In June 1998, DEQ performed an integrated site
assessment in cooperation with the EPA. The assessment identified the former Brenntag West property
(formerly the Dyce Chemical property and now the Soco West property, OU2) as a potential source of
tetrachloroethene (PCE) and its breakdown byproducts in the groundwater. The investigation also
identified the upgradient Beall property (OU1) as a potential source of trichloroethene (TCE), cis-1,2-
dichloroethene (cis-l,2-DCE) and vinyl chloride. In December 2000, the EPA placed LSPGS on the
National Priorities List (NPL).
Land use within and around the LSGPS is categorized as light industrial, commercial and residential. The
commercial and light industrial facilities include trucking, vehicle repair, truck tank manufacturing,
chemical repackaging, petroleum pipelines, machine shops and auto salvage. The former Comet Oil Site,
proposed for the NPL in 1988, is located on the east and northeast border of the LSGPS, upgradient of the
OU2 source. There are 81 commercial and light industrial businesses, and there are an estimated 75
residential single-family residences, two trailer parks, and one apartment complex located within the
LSGPS boundary. LSGPS is bordered by the Yellowstone River on the west and northwest; some
wetlands and ponds are included in the LSGPS area.
In 2002, the DEQ conducted a remedial investigation (RI) that included surface and subsurface soil
sampling, monitoring well construction and groundwater sampling, aquifer testing, surface water and
sediment sampling and soil vapor sampling in the LSGPS area. Based on the RI results, the EPA and
DEQ evaluated remedial alternatives, as documented in the July 2004 Proposed Plan. The November
2004 Plan detailed the human health risks, past activities and the preferred remedial actions for the site.
Based on the public meeting and comment period, the EPA and DEQ selected a final remedy, as
documented in the 2005 LSGPS site-wide Record of Decision (ROD). The 2011 Remedial Design/
Remedial Action Consent Decree (DOJ 2011) identified OU1 in the area of the Beall source and OU2 in
the Brenntag/Soco source area.
The RD process is under way at OU2, with the goal of addressing contamination associated with the Soco
West source area and affected groundwater under adjacent properties. Site characterization has continued
in the period between publication of the ROD and the present. This optimization review considered both
historical and more recent data to develop recommendations.
2.2 Source Areas
Several source areas have been identified within the former chemical handling facility at OU2. Site data
suggest that contamination was released at different times and by different mechanisms in several smaller
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source areas. The priority contaminant of concern (COC) and parent constituent on site is PCE. PCE in
the shallow subsurface has undergone anaerobic degradation stimulated by releases of petroleum
hydrocarbons, including benzene, toluene, ethylbenzene, and xylenes (BTEX) serving as carbon sources
for anaerobic processes. Anaerobic decay products of PCE include, TCE, cis-l,2-DCE and vinyl chloride.
PCE and its degradation products TCE, cis-l,2-DCE, and vinyl chloride have been detected at
concentrations above EPA Maximum Contaminant Levels (MCLs) in groundwater. The primary source
areas thought to be contributing contaminant mass to the groundwater plume are listed below and shown
on Figure 2.
Figure 2: Lockwood OU2 Groundwater Plume
Legend
Groundwater Monitoring Wells
PCE Average Concentrations [mg/L;
ND- 0.0001
0 0 0001 - 0 005
O 0.005-D.009
0.009-0,161
0.161-3,0
*f New BonngsWells Summer 2013
^^ Acid Tank Farm Source Area
^^ Northwest Source Area
Pilot Ozone Sparge
^^ SB22 Sourca Area
^^^ Tank Farm Source Area
| j OU2 Groundwalei Plume
OU2 SITE MAP
LOCKWOOD OU2 SOURCE
Billings. Montana
3753-103
26 November. 2013
MV
Note: Groundwater monitoring locations indicated on the map show average PCE concentration for 2000 to 2012. The inset map
shows locations of new borings and groundwater wells installed in Summer 2013. Wells in the vicinity of the soil vapor
extraction (SVE)/ozone sparging system pilot test in the Northwest Source Area are not shown for visual clarity.
Source: GSI, 2014 from data provided by Cardo ATC, 2013.
The primary source areas are the:
Former Tank Farm Area (farthest upgradient)
Former Acid Tank Farm
Northwest Source Area
SB22 Area
The Former Tank Farm Area is located on the upgradient, southeastern portion of the property near where
chemicals were unloaded and stored. Groundwater in the Former Tank Farm Area has high concentrations
of PCE and its breakdown products as well as significant BTEX. Recent samples in this area (MW-400)
indicate high concentrations of cis-l,2-DCE, toluene and PCE in shallow zones. What appear to be minor
source areas are located at the Former Acid Tank Farm (near MP-105), the SB22 (near DP063) Area and
perhaps an additional area around the former rail line in the center of the property (near new well MW-
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403). The Former Acid Tank Farm area shows high concentrations of PCE in the deeper saturated zone
(MW-402). The Northwest Source Area is located along the northwest boundary of the property,
upgradient of Coulson Ditch in a topographic low area. The Northwest Source Area is adjacent to the
Keller Transport property, where access for site characterization has been limited. PCE contamination is
found in the shallow zone, indicating a primary release, rather than transport from an upgradient source.
A pilot-scale soil vapor extraction (SVE)/ozone sparging system was installed in the Northwest Source
Area in 2003.
The hydrostratigraphy of the OU2 source area consists of the following:
From 0 to 15 feet below ground surface (bgs) - surficial clay/silt, saturated below roughly 10 feet
bgs
From 15 to 30 feet bgs saturated sand/gravel
Below 30 feet - sandstone and shale bedrock (Eagle Sandstone).
The water table is at approximately 10 feet bgs, with saturation in both the silty/clay unit and in the
sand/gravel unit. Attachment A includes cross-section and example boring logs from the RI.
2.3 Surface Water, Soils and the Unsaturated Subsurface
Surface water features located in Lockwood OU2 (Area A) include the Coulson Irrigation Ditch, the AJ
Gravel Pond and the Yellowstone River. Analytical results for surface water have not shown
concentrations that exceed human health or ecological screening levels for the primary site COCs.
Site surface soil and shallow subsurface soils are composed of highly heterogeneous, interbedded sands
and gravels, silty sands, clays and silts. Soil contamination has been evaluated based on discrete soil
samples collected from multiple depth intervals in the vicinity of OU2 during site investigations. PCE and
other chlorinated volatile organic compounds (cVOCs) released from the diverse primary sources have
migrated to the saturated zone (located at approximately 10 feet bgs). Source area soils show both vertical
and horizontal heterogeneity and discontinuous concentrations of the primary COCs. The distributed
nature of source materials adds complexity to evaluating and selecting remedial strategies. High
concentrations of PCE were detected in soils in the area of PT-02 (2,404 milligrams per kilogram [mg/kg]
at 6 to 8 feet bgs). Fligher concentrations of cis-l,2-DCE are detected in soils located upgradient,
especially near boring BH M (12,000 mg/kg at 9 to 11 feet bgs), most likely caused by oxygen depletion
resulting from high BTEX in the Former Tank Farm Area. These high concentrations of cVOCs imply the
presence of non-aqueous phase liquids (NAPL). Because of the heterogeneity of soil textures, the
majority of the contamination that remains is likely present in the relatively impermeable silt layers,
possibly serving as a long-term secondary source of contamination.
2.4 Groundwater
A groundwater plume in the alluvial aquifer extends to the northwest from the OU2 source area,
ultimately discharging to the Yellowstone River approximately 2,000 feet downgradient of the OU2
source area. Groundwater in the bedrock aquifer does not appear to be affected above MCLs based on
concentrations at bedrock well MW-128. There have been intermittent detections of cVOCs below MCLs
at MW-128, but recent sample results have shown no detections
Centerline concentrations of PCE in the alluvial plume are in the range of 300 to 2,000 micrograms per
liter (|ig/L). The plume broadens downgradient of Coulson Ditch with an approximate width of 1,200 feet
at discharge. The bottom of Coulson Ditch intercepts groundwater and the ditch can be either "gaining"
(receiving groundwater) or "losing" (discharging to groundwater), depending on weather conditions.
Water elevations in the gravel mining ponds downgradient of the source area are coincident with the
water table, indicating that they may be a local sink for groundwater flow, pulling the plume to the north.
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Alluvial aquifer characteristics include a gradient of 0.0064 foot per foot and an estimated hydraulic
conductivity between 0.295 feet per day and 70 feet per day (Tetra Tech 2003). The average saturated
thickness in the OU2 area is about 20 feet. Using a porosity value of 0.25, groundwater seepage velocity
would be in the range of 2.75 feet per year (for low permeability saturated zones) to 654 feet per year (in
the saturated gravel zones).
Groundwater in the OU2 area has been monitored via sampling and analysis of up to 48 wells and
piezometers between 1998 and 2012. Groundwater concentration trends and distribution of mass in OU2
groundwater were evaluated using the Monitoring and Remediation Optimization System (MAROS)
software for the optimization review. The highest dissolved contaminant concentrations were detected at
wells installed to monitor the SVE/ozone sparging system pilot test (PT-02, PT-05 and PT-06) in the
Northwest Source Area. For the time period of 2000 to 2012, wells PT-02, PT-05 and PT-06 show stable
to decreasing concentration trends for PCE by the Mann-Kendall statistical test for trend.
Figure 3 shows groundwater concentration trends for the downgradient plume based on statistical analysis
using MAROS for groundwater data for individual wells. Several well locations within or near the
western part of the plume show decreasing concentration trends (indicated by green icons at wells MW-
003, MW-009, MW-121, MW-008, MW-004, MW-125 and MW-126). In particular, well MW-009,
which had historically high concentrations of PCE and based on the MAROS results is located near the
estimated center of mass for the plume, shows a strongly decreasing trend for PCE. Increasing trends are
evident along the eastern edge of the plume at wells MW-010, MW-006, MW-122 and MW-117.
Increasing trends to the east may indicate plume migration to the east and northeast.
Figure 3: Lockwood OU2 PCE Concentration Trends
Legend
Groundwater Monitoring Wells
PCE Mann-Kendall Concentration
Trends 2000 -2012
Increasing
Probably Increasing
Stable
.' Probably Decreasing
Decreasing
Nan Delect
Na Trend
Insufficient Data
$ New Borings/Weils Summer 2013
-^ Acid Tank Farm Source Area
^^ Northwest Source Area
Pilot Ozone Sparge
^5822 Source Area
^^^ Tank Farm Source Area
i OU2 Grounrtwater Plume
OU2 PCE TRENDS
LOCKWOOD OU2 SOURCE
Billings, Montana
3753 '03
MV
Note: Mann-Kendall statistical concentration trends for PCE are shown for data collected 2000 to 2012. (Note: Wells in the
vicinity of the SVE/ozone sparging pilot test are not shown for visual clarity.).
Source: GSI, 2014 from data provided by Cardo ATC, 2013.
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Groundwater data analysis using the MAROS software indicates that the total dissolved mass of PCE
shows neither an increasing nor a decreasing statistical trend plume-wide (see MAROS reports,
Attachment C), indicating largely stable contaminant mass. Estimates of total dissolved mass indicate that
approximately 20 percent of dissolved PCE is still in the source area, with about half the estimated
dissolved source mass in the Northwest Source Area. No estimates are available for the amount of
contaminant mass in the source area soils. The center of dissolved mass in the plume is near well MW-
009.
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3.0 REMEDIAL ACTION OBJECTIVES
AND SELECTED REMEDY OPTIONS
This section discusses the remedial action objectives from the 2005 ROD and describes the components
of the selected remedy options for OU2.
3.1 Remedial Action Objectives and Affected Media
The ROD identifies the following RAOs for the LSGPS for groundwater, surface water and soil (EPA
2005):
Prevent exposure of humans to groundwater and surface water contaminants in concentrations
above regulatory standards.
Reduce contaminant concentrations in the alluvial aquifer and surface water to below regulatory
standards.
Prevent or minimize further migration of the contaminant plume.
Prevent or minimize further migration of contaminants from source materials (soil) to
groundwater.
The ROD identifies the principal threat waste as chlorinated solvent contamination found in the vadose
zone soil and saturated soils.
Table 3 shows the groundwater cleanup standards and the soil cleanup levels for the LSGPS. The soil
cleanup levels were established based on modeling conducted by the site team during the Feasibility
Study (FS); the modeling was implemented to identify concentrations of COCs that would protect
groundwater from contamination leaching from soil. Table 4 summarizes the affected media on site and
the composition and potential receptor exposure or migration pathways associated with each medium.
Table 3: Contaminants of Concern and Cleanup Levels
Contaminant of Concern
Trichloroethene (TCE)
Tetrachloroethene (PCE)
Cis-l,2,-dichloroethene (cis-
1,2-DCE)
Vinyl chloride
Groundwater Cleanup Standard
(ug/L)
5
5
70
2
Soil Cleanup Standards for
OU2
(US/kg)
720
654
4,898
157
Notes: |ig/kg = micrograms per kilogram; |ig/L = micrograms per liter.
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Table 4: Affected or Potentially Affected Media on Site
Medium
Surface soil (vadose
and saturated at
depth)
Alluvial aquifer
Siltstone/sandstone
bedrock
Location
Ground surface to 10
to 15 feetbgs
15to30feetbgs
Below 30 feetbgs
Composition
Silt, silty clay with sand
lenses, highly
heterogeneous
Can be saturated below 10
feet bgs
Alluvial sand and gravel
aquifer, some cobbles
Eagle Sandstone with some
shale
Groundwater in
interconnected fractures
Potential Exposure /
Migration Pathways
Discharge to alluvial
groundwater
Direct exposure by
excavation
Drinking water wells
historically located in
this unit
Transport to
downgradient surface
water
Not currently affected
Potential for transport
from alluvial and
discharge to bedrock
aquifer (deeper
groundwater)
Notes: bgs = below ground surface.
3.2 Selected Remedy Options
The remedy options selected for OU2 are described in the ROD (EPA 2005) and summarized in Table 5.
The ROD specifies thermal treatment of excavated soils for the Soco Source Area (ex situ thermal
treatment), SVE, and in situ chemical oxidation (ISCO) for affected soils. A permeable reactive barrier
(PRB) and in situ bioremediation (ISB) were selected for source groundwater, with the location and
design of the remedy to be determined after pilot testing. ISB was selected for site-wide groundwater and
was anticipated to include injection of a chemical reductant to stimulate anaerobic biodegradation of
cVOCs.
Site-wide elements of the remedy include long-term groundwater monitoring, five-year reviews (FYR)
and institutional controls (1C), including restrictions on groundwater use. The selected remedy also
includes risk mitigation for potential exposures arising from drinking water sources and indoor vapor
intrusion. Risk mitigation includes monitoring potable water supply wells, and eliminating exposure
through means such as extending the municipal supply line.
Table 5: Remedy Options Selected in the ROD
Remedy
Soil Excavation
Ex Situ Thermal Treatment
SVE/Ozone Sparging
Target Medium
Accessible vadose zone soils
in source
Accessible vadose zone soils
in source area
Inaccessible, vadose zone in
source area
Description
Excavation and removal of soils
Thermal treatment of mixed excavated soils
Apply SVE/ozone sparging (pilot test
conducted in Northwest Source Area, design
in progress)
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Remedy
In Situ Chemical Oxidation
(ISCO)
In Situ Bioremediation
Treatment
Permeable Reactive Barrier
(PRB)
Risk Mitigation
Institutional Controls (1C)
Groundwater monitoring
Five -Year Reviews
Target Medium
Inaccessible saturated zone
soils
Groundwater source and
plume
Source groundwater
Groundwater and subsurface
soils
Commercial property,
affected groundwater
Alluvial aquifer
All site media
Description
Addition of chemical oxidant to affected soil
to catalyze conversion to carbon dioxide
(C02)
Treatment of groundwater with reductants in
situ to stimulate anaerobic degradation -
amendments to be chosen based on
treatability studies; design in progress
Emplacement of reactive materials such that
dissolved contaminants flowing through the
system react with materials forming non-
toxic by-products
Continue monitoring potable water supply
wells, mitigation (such as providing
municipal water) for residences and
commercial property with affected private
water supply wells, Indoor air monitoring
and mitigation where needed.
Restrictions on excavation or drilling into
affected subsurface areas
Collection of contaminant concentration data
to assess remedy performance, progress
toward remedial goals and protectiveness
Documentation of remedy performance and
protectiveness every 5 years
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4.0 FINDINGS
This section outlines the major findings of the optimization review team.
4.1 CSM Implications for Remedial Strategy
The CSM described in Section 2 has the following potential implications for a remedial strategy:
There were multiple historical releases of contaminants within the Soco West source area.
Delineation and characterization of these sources is complex. Uncertainty about the distribution
of primary sources and contaminant mass remaining in the vadose zone may reduce remedial
efficacy, particularly for remedies such as ISCO and excavation that rely on precise identification
of contamination.
Geochemical conditions in source soils may vary due to the presence of residual co-contaminants
(such as petroleum hydrocarbons) as well as variability in lithology.
Increasing PCE concentration trends are evident along the eastern edge of the plume at wells
MW-010, MW-105, MW-006, MW-122 and MW-117 while strongly decreasing trends are
evident at center wells MW-009, MW-008, and MW-121 and wells to the west MW-004 and
MW003 of the plume. Concentration trends may indicate plume migration or dilute expansion of
the plume footprint to the north-northeast of the source.
Groundwater flushes through the site's gravel aquifer at a velocity up to 600 feet per year,
indicating that significant source removal may be apparent in downgradient groundwater
monitoring well concentrations, particularly at locations monitoring transmissive zones with
current high concentrations or decreasing trends, within 5 years.
Site groundwater monitoring wells have screened intervals that are long (10 to 20 feet). The long
interval can introduce sampling-induced variability in analytical results and may obscure the zone
of maximum concentrations. The long screens traverse the fine-grained saturated zone as well as
the coarse-grained alluvial aquifer, introducing uncertainty in evaluating long-term desorption
and remedy efficacy for the two different strata.
High concentrations of cis-l,2-DCE and other PCE degradation products in site groundwater,
particularly in upgradient source areas, indicate that anaerobic biodegradation is an ongoing
process and that the microbial community is highly adapted to consume cVOCs. This observation
supports the choice of an ISB remedy to address source groundwater contamination.
Access to adjoining properties is limited by lack of cooperation from property owners. Access
issues complicate further site characterization and may complicate installation of remedy
components in the plume.
Matrix or back-diffusion from silty layers in both the upper saturated and unsaturated zones may
provide a long-term secondary source of contamination.
The vertical distribution of contamination below the water table, which is currently unknown,
will affect the design and performance of the groundwater remedy.
Overall, several groundwater monitoring wells (MW-004, MW-121, MW-008, MW-009, MW-
125 and MW-126) indicate decreasing concentration trends, particularly in the Northwest Source
Area (PT-01, PT-02, and PT-06) and the downgradient plume along the western edge. Total
dissolved mass estimates for the plume indicate largely stable values, indicating that mass
discharge from the source is balanced by mass discharge to surface water and natural attenuation
mechanisms.
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4.2 Data Gaps
Several key data gaps and uncertainties in the LSGPS OU2 Site CSM were identified during the site
meeting and based on document review.
Preliminary recommendations to address OU2 data gaps were provided in March 2013 by memorandum
and through a short web-based presentation of preliminary findings (see Attachment B). To support RD,
the optimization review team recommended additional depth-discreet data collection. The primary data
gap in designing the remedial response for OU2 is uncertainty about the distribution and magnitude of
historical releases within the former chemical facility. Several primary source areas have been identified,
such as the Former Tank Farm Area and the Northwest Source Area. A detailed history of site operations
and releases is not available, introducing uncertainty into the efficient design of source remedies.
Recommendations for additional characterization are summarized in Table 6 and discussed Section 5.1.
Table 6: Identified Data Gaps
Medium
Data Gap
Recommendation
Unsaturated Soil
(Vadose)
Vertical and horizontal source
areas and extent of highest
contamination
Distribution of PCE degradation
products
Effect of heterogeneity in soils on
SVE/ozone
sparging/ISB/excavation remedies
Detailed delineation of down- and cross-
gradient extent of contamination (proposed
sampling locations are detailed in Section
5.1)
Detailed delineation of fine-grained versus
coarse-grained material to assess back
diffusion
Alluvial aquifer
Vertical and lateral
characterization of high mass
zones
Possible presence of secondary
sources in low permeability soils
below water table
Additional depth discreet groundwater wells
with short screens (5 feet)
Depth discreet groundwater sampling with
multiple PDBs in existing wells (Section
5.1)
Continue area-wide comprehensive
groundwater level monitoring for five-year
reviews
Siltstone/sandstone
bedrock
Extent of contamination
Currently appears unaffected, continue
sampling from bedrock intervals at existing
wells
Notes: PCE = tetrachlorethene; SVE = soil vapor extraction; ISB = in situ bioremediation; PDB = passive diffusion bag.
4.3 Considerations for the Remedial Strategy
A phased remedial approach is recommended for LSGPS OU2. Optimization review team
recommendations for the site's remediation include aggressive source treatment, which is anticipated to
reduce cVOC discharge to the downgradient plume, resulting in decreasing concentration trends and
plume footprints. As the efficacy of source treatment is monitored, additional contingent remedies (for
example, ISB) may be installed as needed in the downgradient gravel aquifer to attain site cleanup goals.
Remedial priorities and decision points are summarized in this section and described in more detail in
Section 5. The relative merits of implementing various remedies for source soils are discussed in detail
below and summarized in Section 5.
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Implementation costs for several remedial technologies to address source soils were evaluated using
Remedial Action Cost Engineering and Requirements (RACER) System version 10.4.0. Table 7 presents
the results of this evaluation. The cost estimates are based on Montana state average costs. Also, the unit
cost of shallow (above 10 feet bgs) and deep soil excavation (10 to30 feet bgs) are nearly equivalent and,
therefore, costs for soil excavation with ex situ vapor extraction and land farming were evaluated only for
shallow soil. In the case of SVE/ozone sparging, no precise costs were available to compare the cost of
installing and maintaining the ozone sparging system. Cost estimates for SVE with granular activated
carbon (GAC) treatment were substituted, with the understanding that this cost estimate may be higher
than the actual costs for ozone sparging.
The levels of certainty for the cost estimates provided are comparable to those typically prepared for
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) FS reports (-30
to+50 percent), and are considered rough estimates for planning purposes.
The optimization review team considers excavation and SVE/ ozone sparging as the two primary, and
potentially complementary, remedial options for soil remediation. The remedial approaches considered
for cost evaluation include:
(1) Excavation and disposal of Shallow Soil (vadose zone, 0 to 10 feet bgs): excavated soil will
remain as bulk and be disposed of as hazardous waste.
(2) Excavation and disposal of Shallow Soil (vadose zone, 0 to 10 feet bgs): excavated soil will be
placed in containers and be disposed of off-site as hazardous waste.
(3) Excavation and disposal of Deep Soil (vadose zone, 0 to 10 feet bgs plus saturated zone 10 to
30 feet bgs): excavated soil will remain as bulk and be disposed of off site as hazardous waste.
(4) Excavation and disposal of Deep Soil (vadose zone, 0 to 10 feet bgs plus saturated zone 10 to
30 feet bgs): excavated soil will be placed in containers and be disposed of off site as
hazardous waste.
(5) Excavation of Shallow Soil (vadose zone, 0 to 10 feet bgs): excavated soil will be treated on
site with ex situ SVE/ozone sparging.
(6) Excavation of Shallow Soil (vadose zone, 0 to 10 feet bgs): excavated soil will be treated on
site with ex situ land farming.
(7) SVE/ozone sparging (approximated cost estimates using published data for a GAC system)
treatment: install new wells for an area approximately equivalent to the Northwest Source Area
and implement SVE/ozone sparging.
(8) SVE/ozone sparging (approximated costs estimated using published data for a GAC system):
use of existing wells (for example, PT-01 through PT-07) with implementation of SVE/ozone
sparging.
(9) ISB: implement ISB for source soils.
(10) On-site thermal desorption support by the existing SVE/ozone sparging system to treat off-
gases.
Table 7 presents the estimated total and unit costs for the remedial alternatives listed above:
Table 7: Cost Estimates for Remedial Alternatives
Remediation Alternative
Excavation - Shallow - Bulk - Hazardous Waste
Excavation - Shallow - Container - Hazardous Waste
Excavation - Deep - Bulk - Hazardous Waste
Total Cost ($)
2,890,000
5,490,000
2,200,000
Unit Cost
($ / cy)
309
590
351
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Remediation Alternative
Excavation - Deep - Container - Hazardous Waste
Excavation - Shallow - ex situ Vapor Extraction
Excavation - Shallow - ex situ Land Farming
SVE/Ozone Sparging - Using New Wells
(approximated based on GAC costs)
SVE/Ozone Sparging - Using Existing Wells (approximated
based on GAC costs)
ISB
On-site thermal desorption - Existing SVE - ozone
Total Cost ($)
4,060,000
1,370,000
1,620,000
680,000
455,000
820,000
1,630,000
Unit Cost
($ / cy)
649
146
174
60
32
73
144
Notes: total costs are based on different areas and/or volumes. Unit costs should be used for comparison purposes. SVE = soil
vapor extraction; GAC = granular activated carbon; cy = cubic yards.
Excavation
The primary technical and logistical advantages of excavation include (1) the certainty that targeted soil
will be remediated, (2) the ability to effectively remediate contamination in tightly bound (low-
permeability) soils, and (3) remediation can occur in a timely fashion once initiated. The technical and
logistical disadvantages of this approach are (1) costs for excavation and disposal of soil as hazardous
waste are high, (2) excavation to 30 feet bgs poses engineering challenges and requires a large site area,
and (3) primary sources are numerous and dispersed through the site.
SVE/Ozone Sparging
SVE/ozone sparging has been pilot tested in the Northwest Source Area. Shallow groundwater wells in
this location have shown decreasing concentration trends in response to the remedy (for example, at
monitoring locations PT-06, PT-02 and PT-01). The primary technical and logistical advantages of
SVE/ozone sparging are: (1) a system using SVE/ozone sparging has already been pilot tested and shown
to be effective, and existing wells can be used as part of the final system, (2) the target treatment volume
does not need to be as precisely defined as for excavation, and (3) unit costs are low. Advantages of
oxidation technologies such as ozone include the potential for rapid and complete destruction of chemical
contaminants without generating a waste stream that is expensive to treat or dispose of. The technical and
logistical disadvantages of this approach are that (1) SVE/ozone sparging still requires delineation of the
most affected soils, so there is less certainty in removing soil contamination that can cause long-term
groundwater contamination relative to more diffuse technologies such as ISB, (2) remediation will likely
need to continue for 2 or more years, (3) there are challenges in removing contaminant mass from low-
permeability materials and (4) oxidation in the subsurface may inhibit natural attenuation through
anaerobic biodegradation. In the case of SVE/ozone sparging, no precise costs were available to compare
the cost of installing and maintaining the ozone sparging system with other remedies. Costs for SVE with
GAC were substituted, with the understanding that this cost estimate may be higher than the actual costs
for ozone sparging.
Thermal Treatment
The ROD includes thermal treatment of excavated soils as a selected remedy option. While the cost
estimate for thermal treatment in the ROD indicates that the cost would be comparable to excavation and
disposal, the optimization review team believes that these costs are underestimates due to the current cost
of providing energy for thermal treatment technologies and the size and distribution of contaminated soils
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on site. The combination of excavation and thermal treatment (ex situ treatment) is cost competitive, but
the successful demonstration of SVE and the cost savings associated with expanding the existing SVE
system make this option more practical.
ISCO
ISCO is a selected remedy option in the ROD for inaccessible saturated soils. The SVE/ozone sparging
remedy piloted in the Northwest source area is a form of oxidative treatment that has been shown to be
effective on site in areas of known high contamination. Advantages and disadvantages of other ISCO
technologies (for example, peroxide/Fenton's reagent) are similar to those discussed for SVE/ozone
sparging. Other ISCO technologies can cause precipitates to form reducing the permeability of the
formation. As with other forms of oxidation/reduction treatment, metals can sometimes be mobilized
during and after treatment. For the purposes of this report, the SVE/ozone sparging system will be
considered rather than other ISCO technologies as its efficacy has already been demonstrated. Other
forms of ISCO treatment may be considered by the site team, but pilot tests should be performed before
selecting from the variety of oxidants available
PRB
The ROD includes PRB treatment of groundwater as a selected remedy option. The optimization review
team believes that this technology is not cost-effective and may not be capable of achieving remedy
objectives. Therefore, no detailed review was performed for this technology.
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5.0 RECOMMENDATIONS
This section provides several recommendations related to remedy effectiveness, cost control, technical
improvement and site completion strategy. Note that while the recommendations provide some details to
consider during implementation, the recommendations are not meant to replace other, more
comprehensive, planning documents such as work plans, sampling plans and QAPPs.
The optimization review recommendations focus on resolving uncertainty with regard to the CSM.
General recommendations on remedial strategy and decision points are also included, but because they
have been developed based on available data and there are data gaps for the CSM, specific
recommendations for further refinements to the RD must be made after data gaps in the extent of
contamination and initial performance of soil remedies have been addressed.
The costs presented do not include potential costs associated with community or public relations activities
that may be conducted before field activities. The estimated costs of these remedial alternatives are
summarized in Table 7.
5.1 Recommendations to Sequence Remedial Approach
A phased remedial approach consistent with an adaptive management strategy is recommended for OU2.
Optimization review team recommendations for the site include additional source area characterization to
refine the RD to target the location of treatment and refine the scale of the remedial components. The
source area remedies are anticipated to include SVE/ozone sparging, with possible excavation in high
concentration areas and ISB treatment for source groundwater. Source treatment is anticipated to reduce
cVOC discharge to the dilute downgradient plume. Monitoring of the downgradient plume is
recommended for a period of 2 to 3 years to assess the effects of source treatment. Additional remedies
for the downgradient plume may be implemented after the effects of source treatment are evaluated.
The following sequence of activities is recommended to optimize RD and future performance at LSGPS
OU2:
Additional groundwater wells are recommended for the source and immediate downgradient
plume. Wells are recommended to be installed at different depths in clusters of three depths using
Rotosonic drilling and 5-foot screened intervals. (Note: this recommendation was largely been
accomplished by the time this report was finalized.)
Sampling with multiple passive diffusion bags (PDBs) in existing wells with long-screen-interval
wells to provide greater vertical characterization at multiple intervals.
Identifying the areas of highest contamination will support locating remedies for optimal mass
removal.
Use existing and new data to prepare highly detailed, OU2-specific cross sections with low-
permeability seams and areas of highest contaminant mass highlighted. Use detailed source-area
data to refine the RD.
Reactivate and expand the SVE/ozone sparging remedy for the Northwest Source Area. The
existing SVE/ozone sparging system may be extended to other, well-defined source areas.
Expand the SVE system to treat excavated soils.
Excavate highly contaminated, low permeability, shallow soil (above 20 feet bgs) and treat ex situ
by expansion of the existing SVE/ozone sparging system. The time and efficacy benefit of
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excavation may outweigh the added cost of excavation. On-site treatment with an SVE/ozone
sparging system already in place will reduce costs and improve efficiency.
Implement ISB treatment in the source area. Placement of the ISB remedy should be based on the
interpretation of data from the additional site characterization recommended above as well as
additional information obtained by expanding the SVE/ozone sparging system. Add the ISB
amendment at the base of the excavations (if implemented) to treat deeper areas of contamination
outside of the SVE/ozone sparging treatment area, at and below the water table in the source area.
Conduct performance monitoring for the source remedy for 3 to 5 years after implementation.
Prioritize source area remediation. Delay implementation of an ISB remedy in the dissolved
leading edge of the groundwater plume until 3 to 5 years of source area remedy performance data
have been collected and analyzed. Given the high rate of groundwater flow, the success of the
source remedy should be apparent in downgradient gravel aquifer wells (for example, MW-007,
MW-122, and MW-009) relatively rapidly. Strongly decreasing concentration trends, and a
reduced or altered plume footprint in response to source treatment may influence the location and
extent of the downgradient plume remedy (ISB).
Carefully monitor the northern and eastern edges of the plume near MW-006, where
concentrations may be increasing because groundwater flow is no longer influenced by pumping
from water supply wells located west of the plume. If concentrations increase past MCLs at well
MW-006, consider installing an additional monitoring well to delineate the plume to the
northeast.
5.2 Recommendations to Characterize the Source Area for Remedy Design Refinement
A more accurate assessment of the location and magnitude of contaminant mass in the dissolved phase
will guide development and implementation of the proposed groundwater remedy. The goals of the
recommendations in the previous section are to (1) identify the general vadose and saturated target
treatment zones, and (2) estimate mass flux from the various source areas. Several of Section 5.1's
recommendations were provided to the site team in March 2013. For the most part, the recommendations
were implemented during the summer of 2013 and are included here for completeness.
Recommendation 5.2.1: In a communication of
March 2013, groundwater wells were recommended
to be installed in clusters of three using Rotosonic
drilling with 5-foot screened intervals at various
locations in the source and near downgradient zone.
Based on communication with the site team, many of
these wells were installed and sampled in the
summer of 2013.
The optimization review team recommended OU2
source area wells for three discreet depths:
A-Depth: Based on lithologic interpretation
of the Rotosonic cores, the upper well should
be placed in the most permeable portion of the silty/low-permeability saturated unit.
B-Depth: Based on lithologic interpretation of the Rotosonic cores, the middle interval well
should be placed in a shallow transmissive section of the upper sand/gravel aquifer.
Benefits of Implementing Section 5.2
Recommendations
Additional well locations will characterize the
lateral extent of contaminant sources, reducing
uncertainty for remedy placement.
Vertical characterization of affected
groundwater will help target remedial activities
and assess remedy performance.
Recommendations optimize efficiency of
groundwater monitoring to track performance
of the source remedy.
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C-Depth: The bottom screen interval should be placed at the bottom of the sand/gravel aquifer
near the contact with bedrock. It is expected that the C-Depth well for each cluster will be
installed first so that the intervals for the A-Depth and B-Depth wells can be identified from the
C-Depth Rotosonic core.
The suggested locations for the well clusters are provided in Attachment B. The optimization review team
understands that there are challenges to conducting characterization in off-site areas because of access
agreements. Lithologic interpretations of the Rotosonic cores in these areas will provide important
information with regard to stratigraphy. Monitoring wells in each of the three depth intervals suggested
will help determine the chemical signature, distribution and mass flux of contamination at the locations
suggested. Water level measurements from discrete interval monitoring wells will also provide improved
information regarding vertical hydraulic gradients.
One well cluster should be placed in, or immediately downgradient of, the upgradient Tank Farm
Source area near borings MP104 and BHM. Contamination in this area appears to be deeper and
more degraded than in other areas of the source. Existing deep sample data in this location exhibit
high concentrations of the PCE degradation product cis-l,2-DCE. This well cluster will provide
the above-mentioned information for the most upgradient source area in OU2.
One well cluster is recommended be installed downgradient from the Former Tank Farm Area
near historical soil boring BHF, west of the Former Acid Tank Farm Area's source area.
Comparing the analytical results from this well cluster with the results from the upgradient well
cluster may help determine if additional sources downgradient of the Former Tank Farm Area
source are contributing contaminant mass to this location.
The optimization review team recommends that a transect of well clusters be installed
perpendicular to groundwater flow near soil borings BF£A, BHB and BHC. This transect would
be downgradient from both the Former Acid Tank Farm and the Former Tank Farm Areas, but
upgradient of the Northwest Source Area and the SB22 Area source. Wells in this area will
characterize the depth and composition of contamination entering the Northwest Source Area.
Quantifying mass entering the Northwest Source Area will support allocation of remedial effort
to each of the sources and will help evaluate the performance of remedies both upgradient and
downgradient of this transect.
The optimization review team recommends that one well cluster be installed for the area
downgradient of the Northwest Source Area and upgradient of Coulson Ditch. The wells in this
area will quantify mass exported from the Northwest Source Area and support remedy
performance evaluations.
The optimization review team recommends that a transect of well clusters be installed for the area
north of Coulson Ditch and south and southeast of monitoring well MW-007. This transect of
wells will provide data to evaluate source-remedy performance and will help estimate mass
discharge downgradient.
Recommendation 5.2.2: The optimization review team suggests sampling with multiple passive diffusion
bags (PDB) in existing long-screen-interval wells to provide greater vertical characterization at multiple
intervals at key wells in the body of the plume such as MW-117, MW-121, MW-122 (20-foot screens)
and MW-007, MW-009, MW-008, and MW-005 (10-foot well screens). PDB analytical results will help
belter characterize the water quality within the saturated depth, which includes two distinct lithologies.
Characterization at discrete depths may also help reduce some of the variability in analytical results seen
in the trend analysis (See MAROS Reports Attachment C, Note PCE results for MW-122). Determining
the optimal sampling depth for long-term monitoring will improve the performance evaluations of the
remedy.
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PDBs are often deployed in 2-foot intervals within each well. The recommendation is to deploy two (10-
foot screens) or three (20-foot screens) PDBs per well with one located near the bottom of the screened
interval and the others in the middle or towards the top of the screen. Once the area of highest
concentration is identified, long-term monitoring can be performed using low-flow methods from that
interval. Selection of final low-flow sampling locations may be aided by in-well borehole flow
monitoring to confirm flow characteristics across the screen lengths.
The optimization review team estimates the cost of sampling with PDBs at the specified wells as about
$20,000 for one event. This cost includes an addendum to the QAPP and field sampling plan for two to
three PDBs per well, including purchase, deployment, retrieval, laboratory analysis, and preliminary data
interpretation.
Recommendation 5.2.3: The optimization review team recommends preparation of highly detailed cross-
sections and maps of high concentration areas as well as heterogeneity within saturated units based on the
sampling described above. Detailed site visualization and analysis are essential to refining the CSM to
support RD.
High-resolution cross-sections and maps can be used to target remediation and assess remedial
performance in areas of highest contaminant mass. The purpose of the detailed cross-sections and maps is
to identify areas of shallow soil contamination with high concentrations and low porosity to optimize
excavations.
5.3
Recommendations for Source Area Soil Remediation
This sections provides recommendations for source area soil remediation based on optimization review
findings.
Recommendation 5.3.1: Given the success of the pilot
SVE/ozone sparging system and the low relative cost, the
optimization review team recommends expanding the
existing pilot-scale SVE/ozone sparging system to include
the full Northwest Source Area and perhaps the adjacent
SB22 Area source. Expansion of the SVE/ozone sparging
system should occur prior to extensive excavation and
prior to ISB applications. The SVE/ozone sparging system
should be expanded to treat soils excavated from other
source areas. If needed, a GAC unit can be installed to
treat cVOC vapors. The operational status of the pilot
SVE/ozone sparging system was not known at the time of
the optimization review, but reactivation and expansion of
the system will most likely not exceed $500,000.
Performance of the system can be evaluated by comparing
the vapor phase mass removed to the operating costs. The
SVE/ozone sparging remedy should be terminated when
mass recoveries are low relative to operating costs and
fuel inputs. Contingent remedies for SVE/ozone sparging
include excavation and ISB treatments. Additional
oxidation technologies (for example, ISCO) may be considered, but pilot tests and monitoring for
undesirable changes in the subsurface (for example changes in porosity, mobilization of metals or
sterilization of microbial communities) should be conducted prior to full-scale implementation.
SVE/ozone sparging has been shown to be
both an effective and cost efficient
remedial alternative for this site.
Excavation with on-site SVE/ozone
sparging treatment is time and cost
efficient and may eliminate the potential
for long-term back diffusion of
contaminants from fine-grained
sediments.
ISB treatment can be used at the base of
excavations to stimulate biodegradation of
contaminants in the saturated zone.
Source area staging of SVE/ozone
sparging/excavation/ISB may
dramatically reduce mass flux to leading
edge of plumes.
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Recommendation 5.3.2: The optimization review team recommends excavation for shallow, low-
permeability soils with high residual (above 1,000 mg/kg) cVOC concentrations. Soils in the Former
Tank Farm Area are recommended for excavation. The decision on where SVE/ozone sparging alone or
excavation with SVE/ozone sparging is most appropriate should be made based on more detailed soil
concentration data, relative permeability and relative cost assessments. Low-permeability and high
concentration soils should be prioritized for excavation. Excavated soils should be managed on-site and
treated ex situ through expansion of the SVE/ozone sparging system. Based on estimated unit costs of
$146 per cubic yard and a rough estimate of 3,000 cubic yards, the cost would be approximately
$400,000.
Recommendation 5.3.3: Emulsified vegetable oil (ISB) treatment can be placed at the bottom of the
excavations to treat deeper saturated soils not treated by the SVE/ozone sparging system.
Based on a cumulative excavation area of approximately 5,000 square feet and a target treatment
thickness of 5 feet below the floor of the excavation, approximately 11,000 pounds of emulsified
vegetable oil might be applied as a 5 percent solution (approximately 25,000 gallons of water) followed
by an additional 25,000 gallons of water. Some contamination may mobilize in the short term, but given
the current extent of the plume and the demonstrated capacity for biodegradation, the mobilized
contamination would not be expected to increase the size of the plume. Recommendations for remedy
performance and plume stability monitoring are provided in Section 5.5. The design for application of
water and vegetable oil to the base of the excavations should be carefully conveyed to the geotechnical
engineer designing the excavation so that it can be considered in the design of the excavation side walls.
The optimization review team anticipates that this recommendation might cost $75,000 to implement.
5.4 Recommendations for Groundwater Remediation
Based on the results of sampling of new wells installed in summer 2013 in the general source area,
groundwater contamination in the source at the Former Tank Farm Area is primarily in the shallow A-
zone. Results show high concentrations of cis-l,2-DCE, indicating strong anaerobic dechlorination
processes most likely the result anaerobic conditions resulting from metabolism of BTEX co-
contaminants. The shallow A-zone sediments are clay/silt, potentially providing a long-term source of
contamination to groundwater because of back or matrix diffusion. A similar pattern is seen at location
MW-403 and to a lesser degree at MW-401 and 402. Very high concentrations of TCE were detected at
the shallow MW-403 interval. Overall, cVOC contamination in the upgradient source area is
characterized by highly degraded PCE sources. Contamination was detected at deeper levels at MW-404,
indicating it may have migrated from upgradient sources.
Analytical results from the Northwest Source Area show shallow, less degraded sources of PCE.
Concentrations of PCE are fairly high at the MW-407 shallow zone, with cis-l,2-DCE seen at higher
relative concentrations in the deeper aquifer. Strong cis-l,2-DCE signals are seen at the line of monitoring
wells upgradient from the Northwest Source Area,
indicating that cis-l,2-DCE may be migrating from
upgradient sources into the Northwest Source Area
and perhaps beyond. c . . , ., , -
- Source area treatment may reduce the scale of
Recommendation 5.4.1: As an initial measure, the or eliminate the need for downgradient
optimization review team recommends SVE/ozone _. _ TOT^ . , . ,
- Combination of ISB with excavation in the
sparging treatment, excavation and limited ISB
applied to excavation areas for shallow vadose and
saturated deposits in the source area. Groundwater
monitoring during active SVE/ozone sparging and 2
years post-remedy should indicate the extent of
Benefits of Implementing Section 5.4
Recommendations
source area will result in cost effective removal
of residual contamination from low-
permeability saturated zones that may function
as long term sources of contamination to
downgradient groundwater.
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reduction of source groundwater concentrations. Groundwater flows quickly at the site (up to 600 feet per
year in the most transmissive zones), and the optimization review team finds it likely that quantifiable
indications of performance of source area remediation will be realized at downgradient locations (for
example, MW-007, MW-009 and MW-117) in less than 3 years.
Monitoring of source area groundwater wells, during and after the excavation/SVE/ozone sparging
treatment, including those recommended above, will indicate reductions in mass flux from treated areas.
Failure to see a response in source area groundwater wells may indicate that smaller, unidentified sources
have not been fully characterized.
The decision on the need for and the location and scale of groundwater treatment should be made after the
performance of the soil remedy has been evaluated. The optimization review team would not recommend
the use of ISB to address concentrations below 10 (ig/L. Source area excavation and SVE/ozone sparging
should be performed before additional ISB treatments (excluding the ISB in excavations) in source and
downgradient groundwater. Rapid remediation of residual soil sources, especially through excavation,
could have a beneficial effect on remediation of groundwater by removing the source of contamination to
groundwater.
Recommendation 5.4.2: If groundwater monitoring suggests that significant contaminant mass remains in
the source areas, an expanded ISB remedy can be considered for both source and downgradient
groundwater. Triggers for further source and plume ISB would be continued high concentrations of PCE
at center line wells (for example, MW-009) or strongly increasing trends at wells indicating plume
migration (for example, MW-006). Application of emulsified vegetable oil would be appropriate through
injection wells for the saturated zone. Given the volumes of water needed to disperse the vegetable oil
throughout the target areas, extracted groundwater would be a reasonable source of water for blending
and injection the emulsified vegetable oil.
The appropriate location and number of injection wells can be selected after analysis of post-SVE/ozone
sparging remedy soil and groundwater data to determine the distribution of remaining mass. Long-term
sources of contamination may remain in the fine-grained saturated zone. Lack of access to the
neighboring property may influence the location of injection and extraction wells.
The optimization review team anticipates that design, implementation and reporting of this injection event
(including well installation) might cost up to $ 1 million. A repeat event for the same volume, likely
needed, would cost less because design, planning and well drilling would have already occurred. The cost
for this remedial approach can be substantially reduced if source soil remediation is effective.
Additional costs would be incurred for remedy performance monitoring as described in the following
section.
5.5 Recommendations for Remedial Performance Monitoring
Historically, more than 40 groundwater wells have been installed in LSGPS Area A for characterization
of groundwater. Many of these wells are installed
outside of the PCE plume and can be eliminated
from routine monitoring (although they may be
retained for periodic groundwater elevation
measurements).
Remedial performance monitoring will be required
for groundwater for all of the remedies proposed,
including excavation, SVE/ozone sparging and ISB.
Benefits of Implementing Section 5.5
Recommendations
Remedy performance can be evaluated more
effectively.
Quantitative metrics demonstrate performance to
stakeholders.
Remedy performance monitoring can prevent
operating remedies past their effective life span.
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Recommendation 5.5.1: A preliminary remedy performance monitoring matrix is included as Table 9.
Approximately 95 groundwater samples per year are recommended for the 3 to 5 years of active source
remediation and post-response action monitoring. Costs for monitoring during active remediation are
anticipated to be approximately $75,000 per year, including sample plan development, sample analysis,
data management and data analysis and reporting. After the excavation/SVE/ozone sparging remedy
performance monitoring period has been completed, groundwater monitoring can be reduced both in
terms of the number wells and frequency of sampling.
Recommended groundwater monitoring wells are listed for various monitoring objectives, including
remediation of the various source areas. Sampling frequencies are recommended for each well group as
well as potential data analysis techniques to support each monitoring objective.
After the PDB sampling and analysis recommended in Section 5.2 above has been completed, sampling
should be conducted with low-flow sampling technology from the interval with the highest concentration
indicated from the PDB sampling. Selection of final low-flow sampling locations may be aided by in-well
borehole flow monitoring to confirm flow characteristics across the screen lengths.
Groundwater samples collected using low-flow sampling methods should be analyzed for typical field
stabilization parameters (including oxidation reduction potential, turbidity and pH), as well as cVOCs
analytes. During the ISB remedy, if implemented, metals and geochemical indicators should be included
in the monitoring program to support assessment of the strength of biodegradation processes, including
ferrous iron, nitrate, sulfate, dissolved organic carbon and alkalinity. Metals should be evaluated to ensure
that oxidation/reduction manipulation does not mobilize constituents such as arsenic and manganese.
Additional data analyses to evaluate remedy performance may include estimates of total mass in each
medium and estimated trends and reduction of total mass as well as mass flux estimates. Concentration
trends for PCE and cis-l,2-DCE at downgradient wells (MW-007, MW-122 and MW-009) should show
statistical decreases after 3 to 5 years.
All area wells should be monitored at least once during a FYR cycle. Data should be evaluated routinely
to determine if a follow-up downgradient plume remedy is required and if the dilute areas of the plume
are being restored in a timely manner. The sampling frequency can be revisited after 3 years of quarterly
sampling.
Particular attention should be paid to future sampling results from MW-006, which delineates the plume's
eastern edge of the northern segment of the plume. With the cessation of groundwater pumping at the
gravel pit and changes in historical extraction due to ICs and abandonment of private supply wells, the
plume footprint may expand laterally in the northeast direction upgradient of the gravel ponds. MW-006
shows increasing trends for PCE, TCE, cis-l,2-DCE and vinyl chloride, although concentrations are still
below cleanup goals, concentration increases may indicate an expansion of the plume footprint. No new
wells are recommended at this time, but may be considered if MW-006 shows continued increases in
COC concentrations.
5.6 Recommendations Related to Green Remediation
No specific recommendations are provided at this time in this category. Green remediation best practices
and environmental footprint analysis can be revisited after characterization activities have been completed
and the site team is developing a more targeted RD. In general:
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The additional characterization suggested should help target the precise location of media to be
remediated and, therefore, reduce the footprint of the final remedy;
Cost savings for the recommended combination of excavation, on-site treatment and SVE should
reduce the project footprint by minimizing soil transport and disposal;
The recommended remedy performance monitoring plan should help reduce the likelihood that
the remedies will be run longer than is cost effective. Performance monitoring will also help
identify underperforming remedies earlier in the remediation process so they can be modified or
replaced, thus saving costly time and material expenditures; and
The proposed, staged remedial response (source remedy followed by monitoring) may prevent
installation of unnecessary remedy components to treat the downgradient plume.
Table 8 summarizes the optimization review recommendations. Table 9 summarizes the recommended
groundwater performance monitoring program.
Table 8: Recommendations Summary
Recommendation
5.2.1 Additional groundwater wells installed
using Rotosonic drilling to characterize
groundwater and vadose zone
5.2.2 Groundwater sampling using PDBs for
vertical delineation of contaminants
5.2.3 Detailed cross-sections
5.3.1 Scale up of pilot SVE/ozone sparging
system for source soils
5.3.2 Excavation and ex situ treatment of low
permeability, shallow contaminated soil
5.3.3 ISB remedy at base of excavation
5.4.1 Delay decision on source groundwater
treatment until performance of soil remedy
has been evaluated
5.4.2 ISB for source and downgradient plume,
if source remedy alone does not shrink plume
5.5.1 Remedy performance monitoring for
source soil treatment and downgradient
groundwater response (3 years)
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$10,000
$500 000
$400,000
$75,000
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$225,000
Change
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Annual
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Notes: PDB = passive diffusion bag; SVE = soil vapor extraction; ISB = in situ bioremediation; N/A = not applicable
Lockwood Operable Unit 2 - Soco/Brenntag Source Area
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Table 9: Recommended Groundwater Performance Monitoring Program
LSGPS OU2
Well Name
MW-011
MW-101
MW-102
MW-103
MW-105
Unit
Source Area
Objective
Evaluate response
to Excavation/
SVE and ISB
treatment
Parameters &
Frequency*
VOCs semi-annually for
2 years after excavation/
SVE (and metals if ISB
used with excavation)
annually after active
remedies discontinued
Analyses
Concentration
trend evaluation,
mass discharge
downgradient mass
removal vs. cost of
remedy
I
MW-400(S, I, D)
MW-401(S, I, D)
MW-402(S, I, D)
MW-403(S, I, D)
MW-404(S, I, D)
MW-405(S, I, D)
MW-406(S, I, D)
MW-407(S, I, D)
MW-411(S, I, D)
PT-01
PT-02
PT-03
PT-04
PT-05
PT-06
PT-07
MW-408(S, I, D)
MW-409(S, I, D)
MW-410(S, I,D)
MW-412(S, I,D)
MW-413(S, I,D)
Source Area
Northwest Source
Area
Downgradient of
Source
Delineate depth of
contamination,
evaluate remedy
performance
SVE
Remedy
Performance
Remedy
Performance
VOCs semi-annually
from highest
concentration interval,
annual from all intervals
during active remedy
VOCs semi-annually for
duration of SVE,
annually thereafter
VOCs semi-annually
from highest
concentration interval,
annual from all intervals
during active remedy
Concentration
trend evaluation,
mass discharge
downgradient mass
removal vs. cost of
remedy
Concentration
Trend
Concentration
trend evaluation,
mass discharge
downgradient,
MW-128
Bedrock
Delineation
Every 2 years
Delineation
vertical extent of
affected
groundwater
Lockwood Operable Unit 2 - Soco/Brenntag Source Area
Billings, Montana
26
Optimization Review Report
-------
Well Name
MW-007
MW-008
MW-009
MW-117
MW-122
Unit
Centerline Wells
Objective
Remedy
Performance -
high
concentration tail
wells
Parameters &
Frequency*
VOCs semi-annually
during active
remediation
Analyses
Concentration
Trend evaluation,
mass discharge
downgradient,
mass removal vs.
cost of remedy
MW-004
MW-005
MW-006
MW-116
MW-121
Plume Tail Wells
Remedy
Performance
VOCs Annual
Concentration
trend evaluation,
plume stability
MW-001
MW-002
MW-003
MW-010
MW-100
MW-103
MW-104
MW-110
MW-123
Upgradient and
Cross Gradient
Delineation
Delineation
upgradient extent
ofOU2
plume/mixing
withOUl plume
cVOCs for 5-Year
Review
Compare to
detection limits
and cleanup
Monitor for plume
expansion
MW-124
MW-125
MW-126
MW-127
Delineate toward
River
Evaluate plume
stability
VOCs Annual
Compare with
detection limits
and cleanup
Monitor for
discharge to river
Additional area
wells
Outside of OU2
Plume
Groundwater
elevation/ flow
direction
5 -Year Review
Groundwater
elevation measure
SVE extraction
wells (vapor)
Source area
Mass removal
Photoionization detector
monthly and cVOCs
quarterly from key wells
for comparison
Mass removal rate
Notes: MW = monitoring well; SVE = soil vapor extraction; ISB = in situ bioremediation; N/A = not applicable; VOC = volatile
organic compounds; cVOCs = chlorinated volatile organic compounds.
Lockwood Operable Unit 2 - Soco/Brenntag Source Area
Billings, Montana
Optimization Review Report
-------
ATTACHMENT A
FIGURES FROM EXISTING SITE REPORTS
-------
Figures from RI Report
Figure 3-3
Log of Borehole MW007
Log of Borehole MWO11
Log of Borehole MW102
Attachment A
Figures Excerpted from Site Documents
-------
A
NORTHWEST
3,150-
3,145-E-
3,140-E-
3,135-E-
3,130-E-
3,125
3,120
3,115-E-
3,110-E-
3,105-E-
3,100-E-
3,095
3,090
3,085
3,080
3,075
3,070
3,065
3,060
3,055
3,050
3,045
3,040
3,035 -E-
3,030
A1
SOUTHEAST
MW219
-3,150
-3,145
-3,140
-3,135
3,130
3,125
3,120
3,115
3,110
3,105
3,100
3,095
3,090
3,085
3,080
3,075
3,070
3,065
3,060
3,055
3,050
3,045
3,040
3,035
3,030
LOCKWOOD SOLVENT GROUNDWATER PLUME SITE
CROSS SECTION A-A' - LOCATOR MAP
Legend
MW - Monitoring Well Locations
TD - Total Depth
BGS - Below Ground Surface
& - Groundwater Level
- Silty Clay / Silt / Fine Sand
CSS3 - Gravels With Sand
| | - Bedrock
Elevations Listed In Feet Above Mean Sea Level
Well Detail
Riser
Screened Interval
325
325
650
I
SCALE IN FEET -1 inch = 325 feet
VERTICAL SCALE EXAGGERATED 15X
LOCKWOOD SOLVENT GROUNDWATER PLUME SITE
BILLINGS, MONTANA
FIGURE 3-3
GEOLOGIC CROSS SECTION
A-A'
Tetra Tech EM Inc.
-------
LOCKWOOD SOLVENT
GROUNDWATER PLUME SITE
YELLOWSTONE COUNTY
MONTANA
LOG OF BOREHOLE
Borehole/Well ID: M WOO 7
(0
s
i.
c
o
>
HI
-_
3095.0-.
sflaa-fu
\
3093 0-
3092.0-
3091 .0-|
3090.0-:
3089.0-j
3088.0-:
3087.0-:
3086.0-:
3085.0-:
3084.0-j
3083.0-:
3082.0-:
3081 .0-
I
3080.0T
.
3079.0-
-
3078.0-:
:
3077.0-
j
in
0)
£
£
s.
Q
-2-
.^
~
77
B||
s-=|
- :p
- !P
~ Q
-%
12 : 1
n D
-I
141
~b
j|
17 ES
^^
o
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y)
o
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>
£ O
_ioi
V/v
* c-O
8I
fe;
x^?
^|
&:'<;^:'i:
J&W
^.'^t
Ob'-'/i'h
T0!'x^:.'e
fet
Qfe^
«?
Lithologic Description
Ground Surface
Sandy Gravel
Clay
Dark Brown
Sandy Gravel
Medium-brown
g
Q.
0)
T§ "5
CO CO
0) 0)
XK
3 n
ll
15
(0 Q.
= E
o n
(0(0
0)
1-i
~ i"
O o
s o
c
i
»
i
E
I)
1
g
: "'.
|
DRILLING DATE: 9-29-99 BOREHOLE DIAMETER (in.): 8.5
DRILLING METHOD: HSA WELL CASING DIAMETER (in.): 2.0
BOREHOLE DEPTH (ft bgs): 35 TOC ELEVATION (ft AMSL): 3096.44 F^T T CH* 1
TOTAL WELL DEPTH (ft btoc): 31 .45 GROUND ELEVATION (ft AMSL): 3093.84 Utf ** 6
LOGGED BY: P. Bray DRILLING CO.: Maxim 7 Wes( 6(n Avenu Sui(e 61 2
CLIENT: MDEQ WATER LEVEL (ft btoc): 8.81 Helena Montana
PROJECT NO.: S1176-10RIRPRT GROUNDWATER ELEV (ft AMSL).: 3087.63 (406)442-5588
-------
©LOCKWOOD SOLVENT LOG OF BOREHOLE
GROUNDWATER PLUME SITE
Borehole/Well ID: M WOO 7
VPI 1 OI/I/QTOA/P POIIA/TV
i c,ii\jvv*j i ly/vc i^u/t/iv f F
MOJVTOAM
Elevation (+/- AMSL)
3076.0-;
3075.0-j
3074.0-:
3073.0-:
3072.0-:
3071 .0-:
3070.0-j
3069.0-j
3068.0-;
3067.0-:
3066.0-:
3065.0-:
3064.0-:
3063.0-:
3062.0-;
3061 .0-;
3060.0-j
3059.0-j
3058.0-j
3057.0-:
(/)
O)
.a
£
f
&
1ST
19T
20 T
21-;
22^
23^
24^
25 -i
26^
27-.
28,-.
2Q~.
30 -_
31 ~_
32 -E
33 T
34^
36^
37^
Lithologic Symbol/
Recovery
Sffi&SIS
ife^s*
&H&&iS
:^&:S5
Ife^s
Bw^SSj
:^oS;?
mm
m$$
msm,
mm
b.WSio-b
^B:!=
p^S
S.W9--S-S
gassp
ife^s
&M9&3
P
tiOp/ji-y
^"oS^I
;ps§s
SMSlS
^e:s:«
«fe^S
d.WPIiii'b
^ps:^
S.H^J»I
!?tfe^S
;|fe^s
a.ys?^
^^:-
fe*
sH.P':ld-ti
Lithologic Description
Sandstone
Gray
End of Log
Headspace PID
Reading
O ra
o> i
o-c
§1
(0 Q.
o n
(0(0
Monitoring Well
Completion
: : : ~ : : : :
!;! i!!!!
:;; !;;;;
: : : E : : : :
... - - -
: : : : : : :
... _ . . . .
::: =::::
: : : E : : : :
;;; |;;;i
: : : ~ : : : :
::: =\\\l
... ....
::: E:::!
: : : : : : :
III =::::
... _ . . . .
: :: _ : :: :
: : : : : : :
;;;©:::
DRILLING DATE: 9-29-99 BOREHOLE DIAMETER (in.): 8.5
DRILLING METHOD: HSA WELL CASING DIAMETER (in.): 2.0
BOREHOLE DEPTH (ft bgs): 35 TOC ELEVATION (ft AMSL): 3096.44 F^T T CH* 1
TOTAL WELL DEPTH (ft btoc): 31 .45 GROUND ELEVATION (ft AMSL): 3093.84 Utf ** 6
LOGGED BY: P. Bray DRILLING CO.: Maxim 7 Wes( 6(h Aven Sui(e 61 2
CLIENT: MDEQ WATER LEVEL (ft btoc): 8.81 Helena Montana
PROJECT NO.: S1176-10RIRPRT GROUNDWATER ELEV (ft AMSL).: 3087.63 (406)442-5588
-------
LOCKWOOD SOLVENT
GROUNDWATER PLUME SITE
YELLOWSTONE COUNTY
MONTANA
LOG OF BOREHOLE
Borehole/Well ID: M W011
(0
s
<
~!.
i-
c
>
HI
-
3098.0-:
3097.0-1
3096.0 I
juab.u .
3095.0-:
3094.07
3093.0-1
3092.0^
3091 .0-:
3090.0-:
3089.07
3088.0-:
3087.07
3086.0-1
3085.0-:
3084.07
3083.0-:
3082 0-
3081 .0-:
3080.0^
3079.07
O
.Q
E
"w" M
0) OT
^ o
^"^ O
^ "o
0. f
Q J
-3-
-2 -E
-1T
I
-
1-1
5-E
6^
7-_
107:
11-z
127:
w=
-
:^
16^p
;,^C
Lithologic Description
£<
ffi
>
o
K
Ground Surface
Clay
Medium brown
%p Sand and Gravel
ijj'S Medium brown
-------
LOCKWOOD SOLVENT
GROUNDWATER PLUME SITE
YELLOWSTONE COUNTY
MONTANA
LOG OF BOREHOLE
Borehole/Well ID: M W011
(0
s
Elevation (+/-
3078.0-j
3077.0-j
3076.0-:
3075.0-:
3074.0-:
3073.0-:
3072.0-:
3071 .0-;
3070.0-
3069.0-1
3068.0-j
3067.0-j
3066.0-:
3065.0-:
3064.0-:
3063.0-;
3062.0-;
3061 .0-;
3060.0-j
3059.0-j
O)
.a
£
f
18-i
21 i
22 T
23 T
24 -:
25 T
26-
27^
28-;
29^
30 T
31^
32 -:
33^
34^
35^
36^
37-
o
E
Lithologic Sy
Recovery
Lithologic Description
End of Log
a
Headspace P
Reading
3 re
11
(0 Q.
o re
(0(0
0)
Monitoring W
Completion
: : : '.'.'.:
::: =::::
... ...
: : : : : : :
... _ . . . .
i;i E;;;:
... ....
: : : E : : : :
... . . . .
::: =::::
::: E::::
i : : : : : :
::! E::::
;;; i;;;!
: : : : : : :
;;; E;;;!
ill
DRILLING DATE: 9-30-99 BOREHOLE DIAMETER (in.): 8.5
DRILLING METHOD: HSA WELL CASING DIAMETER (in.): 2.0
BOREHOLE DEPTH (ft bgs): TOC ELEVATION (ft AMSL): 3153.39 F^T T CH* 1
TOTAL WELL DEPTH (ft btoc): GROUND ELEVATION (ft AMSL): 3096.04 Utf ** 6
LOGGED BY: P. Bray DRILLING CO.: Maxim 7 Wes( 6(n Aven Sui(e 61 2
CLIENT: MDEQ EPA WATER LEVEL (ft btoc): 7.88 Helena Montana
PROJECT NO.: S1176-10RIRPRT GROUNDWATER ELEV (ft AMSL).: 3113.90 (406)442-5588
-------
LOCKWOOD SOLVENT
GROUNDWATER PLUME SITE
YELLOWSTONE COUNTY
MONTANA
LOG OF BOREHOLE
Borehole/Well ID: MW102
Elevation (+/- AMSL)
3103.7
3102.0-j
3101,0-:
3100.0-j
3099.0-:
3098.0-:
3097.0-:
3096.0-:
3095.0-j
3094.0-:
3093.0-j
3092.0-:
3091 .0-:
3090.0-:
3089.0-:
3088.0-j
3087.0-!
3086.0-:
3085.0-:
3084.0-:
Depth (n bgs)
Lithologic Symbol/
I
4-Wt
-£fe
5-
_
_
8-E
10-E
n _
\2. _
1ST
14-1
16-1
17-E
1ST
m ~ "~\
iy _
20- 5j£C
Lithologic Description
£*
1
u
&
Ground Surface
^ A/o samples
m
^| Gravel
11 Fill, coarse *
Silty Clay
^^Dark black, silty clay, stained ^/
Siltv Clav
Gray to black, stained /
Silty Clay
Gray to black
Clay
Dark gray to black, kaolinitic
Clay
As above
Clay
As above
Clay
As above
niit Siltv Sand
N^BIack, very fine, well-sorted, silty /
?c\ /
Headspace PID
Reading
9999+
3158
9999+
9999+
3343
165
62
22
3 «
o> i
o-c
§1
(0 Q.
o n
(0(0
Monitoring Well
Completion
1
:::
-
|
^
=
Z
=
=
^
=
S
^
=
=
~
=
^
=
^
=
E
=
E
^
|
=
I
DRILLING DATE: 6-20-02 BOREHOLE DIAMETER (in.): 8.25
DRILLING METHOD: HSA WELL CASING DIAMETER (in.): 2.0
BOREHOLE DEPTH (ft bgs): 33 TOC ELEVATION (ft AMSL): 3103.28 F^T T CH* 1
TOTAL WELL DEPTH (ft btoc): 33 GROUND ELEVATION (ft AMSL): 3103.65 Utf ** 6
LOGGED BY: J. Faubion DRILLING CO.: SK Geotechnical 7 Wes( 6(n Avenue Suite 612
CLIENT: MDEQ WATER LEVEL (ft btoc): 10.42 (10/28/02) Helena Montana
PROJECT NO.: S1176-10RIRPRT GROUNDWATER ELEV (ft AMSL).: 3092.86 (406)442-5588
-------
LOCKWOOD SOLVENT
GROUNDWATER PLUME SITE
YELLOWSTONE COUNTY
MONTANA
LOG OF BOREHOLE
Borehole/Well ID: MW102
Elevation (+/- AMSL)
3083.0-:
3082.0-j
3081 .0-:
3080.0-j
3079.0-:
3078.0-:
3077.0-:
3076.0-;
3075.0-;
3074.0-j
3073.0-j
3072.0-j
3071 .0-:
3070.0-:
3069.0-1
3068.0-;
3067.0-;
3066.0-j
3065.0-:
3064.0-j
O)
.a
£
f
&
21 T
;
24^
25.
26-
27-.
28 T
30^
31
32-
33-
34^
35 -i
36^
37^
38^
39 -;
40-
Lithologic Symbol/
Recovery
INSl
WVtvrrti
iftl
as
l-SSi;t]!l
?>&i:-f§:?.
$ik
^i
^^i-iwj
I!
Lithologic Description
\ C/ay /
\Dark-gray to black, kaolinitic /
\ Gravels /
^ \Coarse / y
\ Sand with Gravel /
\ \Black, medium and coarse / /
\ Sandy Gravels /
^ \Black to gray, poorly sorted with coarse / y
\ Sand /
\Gray, medium-grained, well-sorted 1
\ Grave/ /
\ Poorly sorted, angular /
Gravels
Coarse, sub-rounded to sub-angular
Sand
^^Fine-grained, well-sorted /
No Samples
\Bedrock /
Sandstone, dark gray /
End of Log
Headspace PID
Reading
19
14
20
10
8.7
18
3 n
11
(0 Q.
o n
(0(0
Monitoring Well
Completion
^
=
=
=
=
^
^
=
=
=
^
i
i
=
=
=
=
~
r-
=
p
-
X
DRILLING DATE: 6-20-02 BOREHOLE DIAMETER (in.): 8.25
DRILLING METHOD: HSA WELL CASING DIAMETER (in.): 2.0
BOREHOLE DEPTH (ft bgs): 33 TOC ELEVATION (ft AMSL): 3103.28 F^T T CH* 1
TOTAL WELL DEPTH (ft btoc): 33 GROUND ELEVATION (ft AMSL): 3103.65 Utf ** 6
LOGGED BY: J. Faubion DRILLING CO.: SK Geotechnical 7 Wes( 6(n Avenue Suite 612
CLIENT: MDEQ WATER LEVEL (ft btoc): 10.42 (10/28/02) Helena Montana
PROJECT NO.: S1176-10RIRPRT GROUNDWATER ELEV (ft AMSL).: 3092.86 (406)442-5588
-------
ATTACHMENT B
INTERIM OPTIMIZATION MEMORANDUM
AND PRESENTATION FROM MARCH 2013
-------
Attachment B
Interim Optimization Memorandum and Presentation
OU2 Memorandum: Preliminary Well Location Recommendations
OU2 Presentation: Optimization Review Interim Update
-------
March 15,2013
MEMORANDUM
TO: Kirby Biggs, USEPA TIFSD
FROM: Mindy Vanderford
Doug Sutton
RE: Lockwood Solvent Groundwater Plume Site, OU2
Preliminary Well Location Recommendations
USEPA TIFSD is supporting remedial design stage optimization activities at the Lockwood
Solvent Groundwater Plume Site (LSGPS) near Billings, Montana, USEPA Region 8. As part of
remedial design optimization, the review team has been tasked with evaluating potential
groundwater well locations for OU2 to 1) improve source area characterization and 2) provide
performance monitoring for future remedial actions.
The following preliminary recommendations are based on a review of existing OU2 groundwater
and soil data, cross-sections, site reports and a site visit conducted February 28, 2013.
Preliminary recommendations are being provided prior to the final optimization report to help
scope and budget well installation activities. These preliminary recommendations are
representative of our current interpretation, and the recommendations may change as data are
further interpreted over the next few weeks.
The overall source area of LSGPS OU2 consists of a number of smaller potential sources of
contamination. Site data suggest that contamination was released at different times and by
different mechanisms in each source area. The primary areas thought to be contributing
contaminant mass to the groundwater plume are listed below and shown on Figure 1.
Tank Farm Source
Acid Tank Farm Source
Northwest Source
SB22 Source
The shallow subsurface of the source zone consists of a surficial silt/clay/sand layer extending
to approximately 15 feet below ground surface (bgs). The silty upper layer is underlain by a
sand/gravel unit extending to the sandstone bedrock at approximately 30 ft bgs. Both the
silt/sand and the sand/gravel units are saturated. Monitoring wells installed in the source are
screened across both the low and high-porosity layers.
In order to choose between different remedial options and optimize remedial response, the
optimization team recommends that additional depth-discreet data should be collected in the
source area and that the input or mass flux from each of the smaller sources should be
quantified. To this end, preliminary well installation recommendations are detailed below and
shown on Figure 1.
Wells are recommended to be installed in clusters of three using rotosonic drilling and
the following 5-ft screened intervals.
o A- Depth: Based on interpretation of the rotosonic core, the upper well should be
placed in the most permeable portion of the silty/low-permeability saturated unit.
-------
March 15,2013
o B-Depth: Based on interpretation of the rotosonic core, the middle interval well
should be placed in a shallow transmissive section of the upper sand/gravel
aquifer.
o C-Depth: The bottom interval well should be placed at the bottom of the
sand/gravel aquifer near the contact with bedrock. It is expected that the C-
Depth well for each cluster will be installed first so that the intervals for the A-
Depth and B-Depth wells can be determined from the C-Depth rotosonic core.
The suggested locations for the well clusters are provided below. Interpreting the
rotosonic cores in these areas will provide important information with regard to
stratigraphy. Monitoring wells in each of the three suggested depth intervals will help
determine the chemical signature, distribution and mass flux of contamination at the
suggested locations. Water level measurements from discrete interval monitoring wells
will also provide improved information regarding vertical hydraulic gradients.
o One well cluster should be placed in or immediately downgradient of the
upgradient Tank Farm Source area near borings MP104 and BHM.
Contamination in this area appears to be deeper and more degraded than in
other areas of the source. Existing deep sample data in this location are
characterized by high quantities of the chlorinated solvent degradation product
DCE. This well cluster will provide the above-mentioned information for the most
upgradient source area in OU2.
o One well cluster is recommended downgradient from the Tank Farm area near
historic soil boring BHF, west of the Acid Tank Farm source area. Comparing the
sampling results from this well cluster with the sampling results from the
upgradient well cluster may help determine if additional sources downgradient of
the Tank Farm Source are contributing contaminant mass to this location.
o A transect of well clusters is recommended for a line perpendicular to
groundwater flow near soil borings BHA, BHB and BHC. This transect is
downgradient from both the Acid Tank Farm and the Tank Farm but upgradient
of the Northwest Source and the SB22 Source. Wells in this area will
characterize the depth and composition of contamination entering the Northwest
Source Area. Quantifying mass entering the Northwest Source area will support
allocation of remedial effort to each of the sources and will help evaluate the
performance of remedies both upgradient and downgradient of this transect.
o One well cluster is recommended for the area downgradient of the Northwest
Source and upgradient of Coulson Ditch. The wells in this area will quantify
mass exported from the Northwest Source area and support remedy
performance evaluations.
o A transect of well clusters is recommended from the area north of Coulson Ditch
and south/southeast of monitoring well MW-007. This transect of wells will
provide data to evaluate source-remedy performance and will help estimate
mass discharge downgradient.
Additional shallow soil and groundwater investigations will likely be recommended to delineate
individual source areas that are net yet fully delineated. It is likely that the investigations will
involve direct-push technology and real-time field measurement supported by confirmatory soil
samples. The scope of these investigations will likely be informed to some degree by the data
collected from the installation and sampling of the above monitoring wells. For that reason, it is
recommended that the shallow soil and groundwater investigation take place after the above
wells have been installed, developed, surveyed, gauged, and sampled at least once.
-------
Groundwater F ow Direction
Legend
Recommended New Well
Locations
Existing Monitoring Wells
Acid Tank Farm Source Area
Northwest Source Area
SB22 Source Area
Tank Farm Source Area
Former Tank Areas
OU2GW Plume
OU2 Area Property Boundaries
Preliminary Draft
Scale (FT)
0 30 60
PRELIMINARY
WELL LOCATION
RECOMMENDATIONS
LOCKWOOD OU2 SOURCE
Billings, Montana
job NO. 3753.103
Date
15 March, 2013
Scale As Shown
Drawn By: |\/|V
Revision:
0
Figure 1
-------
11/25/2013
Lockwood Solvent
Groundwater Plume Site
Optimization Review Interim Update
Doug Sutton / Tetra Tech
Mindy Vanderford / GSI
USEPATIFSD
April 15, 2013
Optimization Review Interim Update
> US EPA National Optimization Strategy
> LSGPS Goals and Objectives
> OU1 - Beall Source Area
> CSM Review
> OU1 Recommendations
> OU2 - Soco Source Area
> CSM Review
> OU2 Recommendations
April, 2013
LSGPS
-------
11/25/2013
EPA's Definition of Optimization
Efforts at any phase of the removal or remedial response to
identify and implement specific actions that improve the
effectiveness and cost-efficiency of that phase. Such
actions may also improve the remedy's protectiveness and
long-term implementation which may facilitate progress
towards site completion.
To identify these opportunities, regions may use a systematic
site review by a team of independent technical experts,
apply techniques or principles from Green Remediation or
Triad, or apply other approaches to identify opportunities
for greater efficiency and effectiveness.
From: National Strategy to Expand Superfund Optimization Practices from Site Assessment to Site Completion,
September 2012
April, 2013
LSGPS
*srt
Optimization Comp
Site Discovery
&
Long-term Response Action | sile completion
Operation & Maintenance
Site Assessment
Remedial Investigation
You Are Here
April, 2013
LSGPS
-------
11/25/2013
LSGPS Project Go
Remedial Design for OU1 and OU2
- Review CSM for data gaps
- Recommend additional characterization
- Support choice of remedial components that are
protective and maximize cleanup while minimizing
effort/cost/risk
Source Treatment
Plume Treatment and Management
Remedial Performance Monitoring
April, 2013
LSGPS
-------
11/25/2013
OU1 - Beall Trailers Sou
. .Trailer
Steam Bay
April, 2013
LSGPS
4
-------
11/25/2013
Historic Trailer Washing
- TCE Tank and Oil/Water separator
Property Redevelopment will retain function
GWflow to N/NW- Historic municipal well to West
Upper Terrace - Fine-grained zone thicker than at OU2
Proposed Remedies -
- SVE or Excavation?
- Enhanced Bioremediation
- MNA
April, 2013
LSGPS
OU1 Subsurface Observatio
MW-201
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-------
11/25/2013
OU1 Subsurface Observations
MW-201
Zj -
.-
: :
glU-.^-^^^^-, /
II Contamination smear zone
|i 38 - 45 ft bgs downgradient
s
k Long well screens
Low resolution of contamination
OU1 - Groundwater Plume
6
-------
11/25/2013
OU1 Hydraulic Conductiv
Simulated hydrograph generated
with following parameters:
- Flow rate: 3 gpm
- Observation well distance: 15 ft
- Hydraulic conductivity: 300 ft/day
- Saturated thickness: 24 ft
Very, very small response, easily
masked by minor trend in regional
water level
Best explanation of result is high
hydraulic conductivity
120 MO »0
April, 2013
LSGPS
Need to better understand vertical distribution of
contamination in saturated zone
- To fully delineate affected groundwaterand soil
- To optimize treatment
How did contamination migrate vertically to top of
bedrock?
- Vertical infiltration or deeper 2nd source?
- Former lines and drain field?
April, 2013
LSGPS
-------
11/25/2013
Groundwater long well screens - do not resolve
areas of high contamination
Why are concentrations still high in west lobe?
- MW-203, MW-210, MW-212
- Will west lobe plume migrate north?
SVE or Excavation?
April, 2013
LSGPS
OU1 Recommendations
Vertical contaminant resolution in source area, west
lobe of plume, and northwest lobe of plume
- Permeable Diffusion Bags at multiple intervals at key wells:
MW-200, MW-201, MW-203 to MW-207, MW-210, MW-211,
toMW-214
- Hydraulic profiling of smear zone and saturated zone to
better understand vertical variability in horizontal flow
parameters
- Based on above results, additional vertical saturated soil
samples will be appropriate
- Based on above results, wells with smaller screen intervals
may be needed
April, 2013
LSGPS
8
-------
11/25/2013
Revise monitoring program based on depth discrete
sampling
Continue monitoring trends at MW-210, MW-212, and
MW-213 for fate of west lobe of plume
April, 2013
LSGPS
SVE
Pros
Easy to expand area of influence
No need to move steam bay
Cons
Will definitely not get everything
Few years of construction and O&M
Unlikely to assist with smear zone
Estimated cost: -$250,000
April, 2013
Pros
Excavation
Definitely get everything in target area
Very small area for excavation
Significant space for staging soil
Likely little volume requiring disposal
Cons
Depth is minor engineering challenge
Need to move steam bay
Unlikely to assist with smear zone
LSGPS
9
-------
11/25/2013
OU2 Soco West Source Area
Historic chemical storage and distribution
PCE source - plume extends to Yellowstone River
- Source area more complex than OU1
Anaerobic degradation products
- Oxygen depleted aquifer - from co-contaminants or off-site
petroleum site?
Shallow fine-grained zone (15 ft bgs), deeper gravel
aquifer to 30 ft. Both saturated.
April, 2013
LSGPS
10
-------
11/25/2013
Proposed Remedies
- SVE, ozone sparging (piloted)
- Excavation
- Enhanced in situ bioremediation -> MNA
- Chemical oxidation
Sequence of remedies
April, 2013
LSGPS
OU2 Source Uncertainties
Source Areas
- Tank Farm Source
- Acid Tank Farm Source
- Northwest Source
- SB22
- Other? BH-F?
Vertical distribution
Soil heterogeneity
April, 2013
LSGPS
11
-------
11/25/2013
OU2 Source Uncertainty
Dissolved Plume
- Vertical characterization
20 ft well screens
- Vapor Intrusion-
residential buildings
- Pumping wells to the
west ceased- migration
toward pond?
- Sewer installation
April, 2013
LSGPS
OU2 Recommendations
New wells in source area
- Rotosonic drilling for better cores
- Clusters of wells with short screens at:
A-Depth - shallow, in most permeable part of silty zone
B-Depth - upper sand/gravel aquifer
C-Depth - near bottom of sand/gravel aquifer and
bedrock
April, 2013
LSGPS
12
-------
11/25/2013
3,126
3,120
3,115
3.110
Area of Interest
\£ f
//
OU2 Recommendations
Downgradient of Ditch- 3 clusters
Mass discharge
Remedy performance
BH-F- 1 cluster
Soil boring high
concentrations
South of Ditch - 2 clusters
Quantify mass exported from the
Northwest Source -
remedy performance
Northwest Source and SB22 - 3 clusters
Picket - 3 clusters
Depth and concentration/flux
From upgradient sources
Acid Tank Farm-1 cluster
High PCE-shallow
Tank Farm - 1 cluster
Deeper contamination
More cDCE
Most upgradient location
PROPOSED MONITORING WELL LOCATIONS
LOCKWOOD SOLVENT GRpUNOWATER PLUME SITE5
13
-------
11/25/2013
New wells in source area
- Detailed cross-sections of source
- Identify magnitude, identity (PCE or c/s-DCE) and
depth of contamination
- Wells to be used for performance monitoring of
remedy
Monitor downgradient plume for stability
Continue vapor profile for residences
April, 2013
LSGPS
OU2 Recommendations
Follow up
- MIP to delineate shallow sources - fine-grained
zone
- Data to guide excavation of shallow sources
Future Remedy Components
- Dependent on results of site characterization
April, 2013
LSGPS
14
-------
11/25/2013
OU1
- Vertical characterization of soil/groundwater
PDBs in long screens
Hydraulic profiling
Additional soil samples from saturated zone
- Monitor west lobe for migration north/east
OU2
- Rotosonic drilling to produce improved cross-sections
- Additional shallow well clusters in source area
April, 2013
LSGPS
Questions?
April, 2013
LSGPS
15
-------
ATTACHMENT C
MONITORING AND REMEDIATION
OPTIMIZATION SYSTEM REPORTS
DOJ (2011). Remedial Design/ Remedial Action Consent Decree. Case l:22-cv-00088-RFC. E. E. S.
U.S. Department of Justice. U.S. District Court, District of Montana, Billings, MT.
-------
Attachment C
MAROS Software Reports
Individual Well Reports
Mann-Kendall Individual Well Trend Analysis
MK PCE Trend Well MW-006
MK PCE Trend Well MW-007
MK PCE Trend Well MW-009
MK PCE Trend Well MW-122
MK PCE Trend Well MW-126
MK PCE Trend Well PT-02
MK PCE Trend Well PT-06
MK cDCE Trend Well PT-05
MK cDCE Trend Well MW102
MK cDCE Trend Well MW117
Plume Level Analyses
Moment Summary
Zeroth Moment PCE
Zeroth Moment Vinyl Chloride
PCE Percent Mass by Well
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
Time Period: 9/22/1998 toll/1/2012
Consolidation Period: No Time Consolidation
Consolidation Type: Median
Duplicate Consolidation: Average
ND Values: 1/2 Detection Limit
J Flag Values: Actual Value
Well
Source/
Tail
Number
of
Samples
Number
of
Detects
Coefficient
of Variation
Mann-
Kendall
Statistic
Confidence
in Trend
All
Samples
"ND" ?
Concentration
Trend
MW002
MW003
MW004
MW005
MW006
MW007
MW008
MW009
MW010
MW011
MW017
MW100
MW101
MW102
MW103
MW104
MW105
MW115
MW116
MW117
MW121
MW122
MW123
MW124
MW125
MW126
T
T
S
S
T
T
T
T
T
S
T
S
S
S
S
S
S
T
T
T
T
T
T
T
T
T
27
27
28
28
28
28
27
28
28
26
6
22
22
23
24
22
21
7
22
22
22
22
22
20
9
22
24
26
28
28
28
28
27
28
24
26
5
21
22
23
23
20
21
1
22
22
22
22
2
20
9
22
0.33
1.09
0.68
1.19
0.88
0.48
0.46
0.38
0.48
0.58
0.45
1.69
0.65
1.21
1.65
1.82
0.66
0.09
0.66
0.67
0.44
0.44
2.17
0.58
0.33
0.47
-150
-223
-254
-69
250
-85
-125
-64
91
-119
-7
13
-7
1
40
-155
-26
-2
-90
42
-58
33
-30
-65
8
-63
99.9%
100.0%
100.0%
91.0%
100.0%
95.1%
99.6%
89.2%
96.3%
99.6%
86.4%
63.1%
56.6%
50.0%
83.1%
100.0%
77.2%
55.7%
99.5%
87.5%
94.6%
81.4%
79.1%
98.2%
76.2%
96.0%
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
D
D
D
PD
1
D
D
S
1
D
S
NT
S
NT
NT
D
S
S
D
NT
PD
NT
NT
D
NT
D
Monday, November 25, 2013
Page 1 of 5
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
cis-l,2-DICHLOROETHYLENE
Well
MW127
MW128
PT-01
PT-02
PT-03
PT-04
PT-05
PT-06
PT-07
Source/
Tail
T
T
S
S
S
S
S
S
S
Number
of
Samples
20
22
5
10
8
4
7
10
7
Number
of
Detects
20
2
5
10
8
4
7
10
7
Coefficient
of Variation
0.85
0.85
0.95
0.36
0.37
0.70
0.67
1.35
0.42
Mann-
Kendall
Statistic
106
-7
0
-11
2
-6
-15
-19
-11
Confidence
in Trend
100.0%
56.6%
40.8%
81.0%
54.8%
95.8%
98.5%
94.6%
93.2%
All
Samples Concentration
"ND" ? Trend
No
No
No
No
No
No
No
No
No
1
S
S
S
NT
D
D
PD
PD
MW002
MW003
MW004
MW005
MW006
MW007
MW008
MW009
MW010
MW011
MW017
MW100
MW101
MW102
MW103
MW104
MW105
MW115
MW116
MW117
MW121
MW122
MW123
T
T
S
S
T
T
T
T
T
S
T
S
S
S
S
S
S
T
T
T
T
T
T
27
27
28
28
28
28
27
28
28
27
6
22
22
23
24
22
22
7
22
22
22
22
22
0
26
28
27
25
28
27
28
27
27
6
17
22
13
12
4
19
1
22
22
18
22
2
0.00
0.50
0.44
0.84
1.39
0.34
0.34
0.41
0.29
0.84
0.68
2.24
0.71
1.11
1.70
1.31
1.68
0.03
0.65
0.81
1.30
0.39
1.33
0
-181
-247
-18
251
-69
-94
-123
97
-41
-6
47
-19
44
-7
-30
96
-2
-46
139
-141
59
-32
49.2%
100.0%
100.0%
63.0%
100.0%
91.0%
97.4%
99.3%
97.2%
79.6%
81.5%
90.1%
69.2%
87.1%
55.9%
79.1%
99.7%
55.7%
89.6%
100.0%
100.0%
94.9%
80.7%
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
ND
D
D
S
1
PD
D
D
1
S
S
PI
S
NT
NT
NT
1
S
S
1
D
PI
NT
Monday, November 25, 2013
Page 2 of 5
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
TETRACHLOROETHYLENE(PCE)
Well
MW124
MW125
MW126
MW127
MW128
PT-01
PT-02
PT-03
PT-04
PT-05
PT-06
PT-07
Source/
Tail
T
T
T
T
T
S
S
S
S
S
S
S
Number
of
Samples
20
9
22
20
22
5
10
8
4
7
10
7
Number
of
Detects
20
9
22
15
1
5
10
8
4
7
10
7
Coefficient
of Variation
0.47
0.63
0.83
0.74
0.78
1.05
1.63
0.28
1.41
0.99
1.32
0.89
Mann-
Kendall
Statistic
-11
-19
-133
-4
-9
-8
-29
10
-4
-7
-31
-9
Confidence
in Trend
62.6%
97.0%
100.0%
53.8%
58.8%
95.8%
99.5%
86.2%
83.3%
80.9%
99.8%
88.1%
All
Samples Concentration
"ND" ? Trend
No
No
No
No
No
No
No
No
No
No
No
No
S
D
D
S
S
D
D
NT
NT
S
D
S
MW002
MW003
MW004
MW005
MW006
MW007
MW008
MW009
MW010
MW011
MW017
MW100
MW101
MW102
MW103
MW104
MW105
MW115
MW116
MW117
T
T
S
S
T
T
T
T
T
S
T
S
S
S
S
S
S
T
T
T
27
27
28
28
28
28
27
28
28
27
6
22
22
23
24
22
22
7
22
22
26
27
28
28
20
28
27
27
23
27
6
21
22
22
20
16
22
0
22
22
0.38
0.17
0.32
0.80
0.92
0.34
0.41
0.34
0.28
0.78
0.55
0.57
0.62
1.86
1.42
2.06
1.36
0.00
0.71
0.66
-197
-218
-260
-92
233
-43
-185
-126
136
-41
-6
134
-8
-11
-14
-83
19
0
-178
111
100.0%
100.0%
100.0%
96.4%
100.0%
79.5%
100.0%
99.4%
99.7%
79.6%
81.5%
100.0%
57.7%
60.3%
62.5%
99.0%
69.2%
43.7%
100.0%
99.9%
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
No
No
D
D
D
D
1
S
D
D
1
S
S
1
S
NT
NT
D
NT
ND
D
1
Monday, November 25, 2013
Page 3 of 5
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
TRICHLOROETHYLENE (TCE)
Well
MW121
MW122
MW123
MW124
MW125
MW126
MW127
MW128
PT-01
PT-02
PT-03
PT-04
PT-05
PT-06
PT-07
Source/
Tail
T
T
T
T
T
T
T
T
S
S
S
S
S
S
S
Number
of
Samples
22
22
22
20
9
22
20
22
5
10
8
4
7
10
7
Number
of
Detects
20
22
1
20
9
22
17
2
5
9
8
4
7
10
7
Coefficient
of Variation
1.08
0.31
1.37
0.41
0.51
0.48
0.71
1.26
0.58
0.94
0.43
0.36
1.06
2.32
0.89
Mann-
Kendall
Statistic
-157
29
17
-61
0
-79
44
-24
-3
-23
6
-4
-19
-35
-15
Confidence
in Trend
100.0%
78.3%
67.2%
97.5%
46.0%
98.7%
91.8%
73.9%
67.5%
97.7%
72.6%
83.3%
99.9%
100.0%
98.5%
All
Samples Concentration
"ND" ? Trend
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
D
NT
NT
D
S
D
PI
NT
S
D
NT
S
D
D
D
MW002
MW003
MW004
MW005
MW006
MW007
MW008
MW009
MW010
MW011
MW017
MW100
MW101
MW102
MW103
MW104
MW105
T
T
S
S
T
T
T
T
T
S
T
S
S
S
S
S
S
27
26
28
28
28
28
27
28
28
27
6
22
22
23
24
22
22
0
3
8
18
16
27
25
27
0
27
0
14
22
22
13
14
22
0.05
0.45
1.07
2.50
1.46
0.77
0.90
0.93
0.05
1.11
0.00
1.82
0.95
1.20
1.91
1.60
1.01
-48
-68
-159
-116
95
-113
-153
-170
-52
-93
0
-57
-21
-5
19
-143
-30
83.5%
93.0%
99.9%
98.9%
96.9%
98.7%
99.9%
100.0%
84.2%
97.3%
42.3%
94.2%
71.1%
54.2%
67.1%
100.0%
79.1%
Yes
No
No
No
No
No
No
No
Yes
No
Yes
No
No
No
No
No
No
ND
PD
D
D
1
D
D
D
ND
D
ND
PD
S
NT
NT
D
NT
Monday, November 25, 2013
Page 4 of 5
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
VINYL CHLORIDE
Well
MW115
MW116
MW117
MW121
MW122
MW123
MW124
MW125
MW126
MW127
MW128
PT-01
PT-02
PT-03
PT-04
PT-05
PT-06
PT-07
Source/
Tail
T
T
T
T
T
T
T
T
T
T
T
S
S
S
S
S
S
S
Number
of
Samples
7
22
22
22
22
22
20
9
22
20
22
5
10
8
4
7
10
7
Number
of
Detects
0
20
19
5
22
0
0
2
22
19
0
1
9
8
3
7
4
7
Coefficient
of Variation
0.00
0.87
1.07
0.95
0.76
1.38
1.40
1.25
0.65
0.67
0.81
0.88
0.84
0.51
0.87
0.80
2.89
0.64
Mann-
Kendall
Statistic
0
-82
-13
-43
-32
-37
-17
6
-107
85
-37
-8
15
-8
-6
-7
-9
-3
Confidence
in Trend
43.7%
99.0%
63.1%
88.0%
80.7%
84.3%
69.6%
69.4%
99.9%
99.8%
84.3%
95.8%
89.2%
80.1%
95.8%
80.9%
75.8%
61.4%
All
Samples
"ND" ?
Yes
No
No
No
No
Yes
Yes
No
No
No
Yes
No
No
No
No
No
No
No
Concentration
Trend
ND
D
NT
S
S
ND
ND
NT
D
1
ND
D
NT
S
D
S
NT
S
Monday, November 25, 2013
Page 5 of 5
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well:
Well Type:
COC:
o nc n't j
7.0E-03
=! R OF m .
O)
-H- i OF ni
c
O
4 nF m .
ro
'c 3 QE-03
o
5 9 OF m
o
1 OE-03
n nF+nn .
User Name: MV
State: Montana
MW006 Time Period: 9/22/1998 to 11/1/2012
T Consolidation Period: No Time Consolidation
TETRACHLOROETHYLENE(PCE) Duplicate Consolidation: Median
Consolidation Type: Average
ND Values: 1/2 Detection Limit
J Flag Values: Actual Value
Date
^ ^ ^P ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^S
4
4
^
»
* ** **» *
Mann Kendall S Statistic:
251
Confidence in Trend:
100.0%
Coefficient of Variation:
1.39
Mann Kendall
Concentration Trend: (See
Note)
Data Table:
Well
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
Well Effective
Type Date
T 6/2/2000
T 11/16/2000
T 7/25/2001
T 10/24/2001
T 2/6/2002
T 5/1/2002
T 8/16/2002
T 10/31/2002
T 6/13/2003
Number of Number of
Constituent Result (mg/L) Flag Samples Detects
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
2.5E-04 ND 1 0
8.8E-04 2 2
2.1E-04 1 1
2.3E-04 1 1
2.5E-04 ND 1 0
2.2E-04 1 1
2.0E-04 1 1
4.1E-04 1 1
6.8E-04 1 1
Monday, November 25, 2013
Page 1 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
MW006
Well
Type
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
Effective
Date
11/12/2003
5/26/2004
10/15/2004
4/28/2005
10/27/2005
4/6/2006
10/27/2006
4/4/2007
10/4/2007
4/17/2008
10/16/2008
4/15/2009
10/8/2009
4/14/2010
10/14/2010
4/13/2011
10/13/2011
4/20/2012
11/1/2012
Constituent
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
User Name: MV
State: Montana
Result (mg/L) Flag
3.1E-04
3.1E-04
2.6E-04
2.9E-04
3.8E-04
4.2E-04
2.5E-04 ND
3.9E-04
4.0E-04
4.2E-04
1.4E-03
6.8E-04
2.2E-03
3.1E-03
4.6E-03
4.1E-03
5.5E-03
7.2E-03
6.0E-03
Number of
Samples
2
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
2
1
1
Number of
Detects
2
1
1
1
1
1
0
1
1
2
1
1
1
1
1
1
2
1
1
Monday, November 25, 2013
Page 2 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu User Name: MV
Location: OU2 State: Montana
Well:
Well Type:
COC:
A np+nn j
^ i nPi-nn .
O)
o o Kpj.nn
c
o
"c 1 5R-00 -
o
g
o
5 OE-01
n np4-nn .
MW007 Time Period: 9/22/1998 to 11/1/2012
T Consolidation Period: No Time Consolidation
TETRACHLOROETHYLENE(PCE) Duplicate Consolidation: Median
Consolidation Type: Average
ND Values: 1/2 Detection Limit
J Flag Values: Actual Value
Date
^VV'o^V'o^VVVVVVVV'
^
,
** * »«. *
»* » » **
* »
*
*
Mann Kendall S Statistic:
-69
Confidence in Trend:
91.0%
Coefficient of Variation:
0.34
Mann Kendall
Concentration Trend: (See
Note)
PD
Data Table:
Well
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
Well Effective Number of Number of
Type Date Constituent Result (mg/L) Flag Samples Detects
T 6/2/2000 TETRACHLOROETHY 2.5E+00 1 1
T 11/16/2000 TETRACHLOROETHY 2.3E+00 1 1
T 10/24/2001 TETRACHLOROETHY 2.4E+00 1 1
T 2/6/2002 TETRACHLOROETHY 1.6E+00 1 1
T 5/1/2002 TETRACHLOROETHY 1.8E+00 1 1
T 8/16/2002 TETRACHLOROETHY 2.0E+00 2 2
T 10/31/2002 TETRACHLOROETHY 2.4E+00 1 1
T 6/13/2003 TETRACHLOROETHY 1.9E+00 1 1
T 11/12/2003 TETRACHLOROETHY 2.9E+00 1 1
Monday, November 25, 2013
Page 1 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
MW007
Well
Type
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
Effective
Date
5/26/2004
10/15/2004
4/28/2005
10/27/2005
4/6/2006
10/27/2006
4/4/2007
10/4/2007
4/17/2008
10/16/2008
4/15/2009
10/8/2009
4/14/2010
10/14/2010
4/13/2011
10/13/2011
4/20/2012
9/7/2012
11/1/2012
Constituent
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
User Name: MV
State: Montana
Result (mg/L) Flag
1.8E+00
2.6E+00
1.7E+00
3.6E+00
9.0E-01
1.2E+00
1.4E+00
1.5E+00
2.1E-01
2.2E+00
2.2E+00
2.8E+00
2.1E+00
1.5E+00
1.3E+00
2.2E+00
2.0E+00
1.9E+00
1.6E+00
Number of
Samples
1
1
2
1
1
1
1
1
2
1
1
1
1
1
2
2
1
3
1
Number of
Detects
1
1
2
1
1
1
1
1
1
1
1
1
1
1
2
2
1
3
1
Monday, November 25, 2013
Page 2 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well:
Well Type:
COC:
1 9F4-nn j
1 OE+00
E 8 OE-01
c
| 6.0E-01 -
§ 4.0E-01 -
c
o
^ 7 OF 01 -
n nF+nn .
User Name: MV
State: Montana
MW009 Time Period: 9/22/1998 to 11/1/2012
T Consolidation Period: No Time Consolidation
TETRACHLOROETHYLENE(PCE) Duplicate Consolidation: Median
Consolidation Type: Average
ND Values: 1/2 Detection Limit
J Flag Values: Actual Value
Date
*
* * * * *
A *
* *»»
*
*
Mann Kendall S Statistic:
-123
Confidence in Trend:
99.3%
Coefficient of Variation:
0.41
Mann Kendall
Concentration Trend: (See
Note)
D
Data Table:
Well
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
Well
Type
T
T
T
T
T
T
T
T
T
Effective
Date Constituent
6/2/2000 TETRACHLOROETHY
11/16/2000 TETRACHLOROETHY
7/25/2001 TETRACHLOROETHY
10/24/2001 TETRACHLOROETHY
2/6/2002 TETRACHLOROETHY
5/1/2002 TETRACHLOROETHY
8/16/2002 TETRACHLOROETHY
10/31/2002 TETRACHLOROETHY
6/13/2003 TETRACHLOROETHY
Number of Number of
Result (mg/L) Flag Samples Detects
9.3E-01 1 1
6.0E-01 1 1
1.1E+00 1 1
5.2E-01 1 1
9.4E-01 1 1
6.1E-01 1 1
9.8E-01 1 1
9.3E-01 1 1
9.6E-01 1 1
Release 352, September 2012
Monday, November 25, 2013
Page 1 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
MW009
Well
Type
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
Effective
Date
11/12/2003
5/26/2004
10/15/2004
4/28/2005
10/27/2005
4/6/2006
10/27/2006
4/4/2007
10/4/2007
4/17/2008
10/16/2008
4/15/2009
10/8/2009
4/14/2010
10/14/2010
4/13/2011
10/13/2011
4/20/2012
11/1/2012
Constituent
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
User Name: MV
State: Montana
Result (mg/L) Flag
7.2E-01
5.6E-01
4.4E-01
7.4E-01
8.4E-01
3.3E-01
2.8E-01
3.1E-01
3.9E-01
9.6E-02
3.7E-01
3.9E-01
8.2E-01
6.4E-01
5.9E-01
5.6E-01
5.7E-01
5.9E-01
4.5E-01
Number of
Samples
1
1
1
2
1
1
1
1
1
1
1
1
1
2
1
1
1
2
1
Number of
Detects
1
1
1
2
1
1
1
1
1
1
1
1
1
2
1
1
1
2
1
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 2 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
Well: MW122
Well Type: T
COC: TETRACHLOROETHYLENE(PCE)
Time Period: 9/22/1998 to 11/1/2012
Consolidation Period: No Time Consolidation
Duplicate Consolidation: Median
Consolidation Type: Average
ND Values: 1/2 Detection Limit
J Flag Values: Actual Value
Date
I.ZbHJU '
1 nFtnn -
8 OE-01
R OF m -
A nc ni .
2 OE-01
n nR-nn .
» » * *
*
* *
*
* *
Mann Kendall S Statistic:
59
Confidence in Trend:
94.9%
Coefficient of Variation:
0.39
Mann Kendall
Concentration Trend: (See
Note)
PI
Data Table:
Well
MW122
MW122
MW122
MW122
MW122
MW122
MW122
MW122
MW122
Well
Type
T
T
T
T
T
T
T
T
T
Effective
Date
8/16/2002
10/31/2002
6/13/2003
11/12/2003
5/26/2004
10/15/2004
4/28/2005
10/27/2005
4/6/2006
Constituent
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
Result (mg/L) Flag
5.5E-01
9.0E-01
9.5E-01
1.6E-01
6.0E-01
6.5E-01
4.4E-01
5.8E-01
1.1E-01
Number of
Samples
1
1
1
1
1
1
1
1
1
Number of
Detects
1
1
1
1
1
1
1
1
1
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 1 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well
MW122
MW122
MW122
MW122
MW122
MW122
MW122
MW122
MW122
MW122
MW122
MW122
MW122
Well
Type
T
T
T
T
T
T
T
T
T
T
T
T
T
Effective
Date
10/27/2006
4/4/2007
10/4/2007
4/17/2008
10/16/2008
4/15/2009
10/8/2009
4/14/2010
10/14/2010
4/13/2011
10/13/2011
4/20/2012
11/1/2012
Constituent
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
User Name: MV
State: Montana
Result (mg/L) Flag
2.6E-01
8.8E-01
6.1E-01
4.1E-01
8.9E-01
8.7E-01
l.OE+00
6.7E-01
8.3E-01
7.8E-01
6.9E-01
8.8E-01
8.9E-01
Number of
Samples
1
1
1
1
1
1
1
2
1
1
2
1
1
Number of
Detects
1
1
1
1
1
1
1
2
1
1
2
1
1
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 2 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
Well: MW126
Well Type: T
COC: TETRACHLOROETHYLENE(PCE)
Time Period: 9/22/1998 to 11/1/2012
Consolidation Period: No Time Consolidation
Duplicate Consolidation: Median
Consolidation Type: Average
ND Values: 1/2 Detection Limit
J Flag Values: Actual Value
c
o
^5
'c
01
o
c
o
Date
6.Uh-UZ
i OF n? -
4 OE-02
» OF n? -
o rip n9 .
1 OE-02
n DF+DD .
*
*
V* *
* * »»»»**
Mann Kendall S Statistic:
-133
Confidence in Trend:
100.0%
Coefficient of Variation:
0.83
Mann Kendall
Concentration Trend: (See
Note)
D
Data Table:
Well
MW126
MW126
MW126
MW126
MW126
MW126
MW126
MW126
MW126
Well
Type
T
T
T
T
T
T
T
T
T
Effective
Date
8/16/2002
10/31/2002
6/13/2003
11/12/2003
5/26/2004
10/15/2004
4/28/2005
10/27/2005
4/6/2006
Constituent
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
Result (mg/L) Flag
5.7E-02
5.1E-02
5.2E-02
3.7E-02
1.2E-02
2.8E-02
2.0E-02
l.OE-02
1.8E-02
Number of
Samples
1
2
1
1
1
1
1
1
1
Number of
Detects
1
2
1
1
1
1
1
1
1
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 1 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well
MW126
MW126
MW126
MW126
MW126
MW126
MW126
MW126
MW126
MW126
MW126
MW126
MW126
Well
Type
T
T
T
T
T
T
T
T
T
T
T
T
T
Effective
Date
10/27/2006
4/4/2007
10/4/2007
4/17/2008
10/16/2008
4/15/2009
10/8/2009
4/14/2010
10/14/2010
4/13/2011
10/13/2011
4/20/2012
11/1/2012
Constituent
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
User Name: MV
State: Montana
Result (mg/L) Flag
1.5E-02
9.4E-03
1.4E-02
8.1E-03
1.2E-02
6.9E-03
7.3E-03
8.4E-03
8.2E-03
9.8E-03
7.3E-03
1.1E-02
1.3E-02
Number of
Samples
1
2
1
2
1
1
1
1
1
1
1
1
1
Number of
Detects
1
2
1
1
1
1
1
1
1
1
1
1
1
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 2 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well:
Well Type:
COC:
_i
E. 5-OEf°1
« T.WI- V 1
C
Ol
o
o
1 nc+ni .
n np4-nn
User Name: MV
State: Montana
PT-02 Time Period: 9/22/1998 to 11/1/2012
S Consolidation Period: No Time Consolidation
TETRACHLOROETHYLENE(PCE) Duplicate Consolidation: Median
Consolidation Type: Average
ND Values: 1/2 Detection Limit
J Flag Values: Actual Value
Date
VVVVV'
* *
Mann Kendall S Statistic:
-29
Confidence in Trend:
99.5%
Coefficient of Variation:
1.63
Mann Kendall
Concentration Trend: (See
Note)
D
Data Table:
Well
PT-02
PT-02
PT-02
PT-02
PT-02
PT-02
PT-02
PT-02
PT-02
Well Effective
Type Date
S 2/6/2002
S 5/1/2002
S 12/20/2002
S 2/26/2003
S 6/13/2003
S 11/12/2003
S 5/26/2004
S 4/20/2012
S 9/7/2012
Number of Number of
Constituent Result (mg/L) Flag Samples Detects
TETRACHLOROETHY 1.8E+01 1 1
TETRACHLOROETHY 6.1E+01 2 2
TETRACHLOROETHY 1.5E+01 1 1
TETRACHLOROETHY 7.7E-01 5 5
TETRACHLOROETHY 9.3E+00 2 2
TETRACHLOROETHY 4.6E-01 2 2
TETRACHLOROETHY 2.8E+00 1 1
TETRACHLOROETHY 5.4E+00 1 1
TETRACHLOROETHY 4.8E-01 3 3
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 1 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
Well
Well
Type
Effective
Date
Constituent
Result (mg/L) Flag
Number of Number of
Samples Detects
PT-02
11/1/2012 TETRACHLOROETHY
3.6E-01
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 2 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well:
Well Type:
COC:
1 4&-02 H
1.2&-02 -
E.
c n np4-m -
S R np4-m -
c
Ol
y A_ np4-m -
O
o
o nPi.ni
User Name: MV
State: Montana
PT-06 Time Period: 9/22/1998 to 11/1/2012
S Consolidation Period: No Time Consolidation
TETRACHLOROETHYLENE(PCE) Duplicate Consolidation: Median
Consolidation Type: Average
ND Values: 1/2 Detection Limit
J Flag Values: Actual Value
Date
*
»
*
»
Mann Kendall S Statistic:
-31
Confidence in Trend:
99.8%
Coefficient of Variation:
1.32
Mann Kendall
Concentration Trend: (See
Note)
D
Data Table:
Well
PT-06
PT-06
PT-06
PT-06
PT-06
PT-06
PT-06
PT-06
PT-06
Well Effective
Type Date
S 5/1/2002
S 12/20/2002
S 2/26/2003
S 6/13/2003
S 11/12/2003
S 3/1/2004
S 5/26/2004
S 4/20/2012
S 9/7/2012
Constituent
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
TETRACHLOROETHY
Number of Number of
Result (mg/L) Flag Samples Detects
1.2E+02 2 2
7.0E+01 1 1
2.1E+01 4 4
2.6E+01 3 3
3.3E+00 2 2
1.3E+00 1 1
1.3E+00 1 1
5.6E+01 1 1
4.5E-01 6 6
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 1 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
Well
Well
Type
Effective
Date
Constituent
Result (mg/L) Flag
Number of Number of
Samples Detects
PT-06
11/1/2012 TETRACHLOROETHY
9.7E-02
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 2 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well:
Well Type:
COC:
5 0&-00 -
4.5&-00 -
_J T-Wl-1 W
o) 7 <\Pi-nn .
*"' ' i nPi-nn .
o
= 9 <>F+nn .
ro
Ol
o
01 nF+nn
i OF m .
n nFtnn .
User Name: MV
State: Montana
PT-05 Time Period: 9/22/1998 to 11/1/2012
S Consolidation Period: No Time Consolidation
cis-l,2-DICHLOROETHYLENE Duplicate Consolidation: Median
Consolidation Type: Average
ND Values: 1/2 Detection Limit
J Flag Values: Actual Value
Date
*
£
Mann Kendall S Statistic:
-15
Confidence in Trend:
98.5%
Coefficient of Variation:
0.67
Mann Kendall
Concentration Trend: (See
Note)
D
Data Table:
Well
PT-05
PT-05
PT-05
PT-05
PT-05
PT-05
PT-05
Well Effective
Type Date
S 5/1/2002
S 12/20/2002
S 2/26/2003
S 6/13/2003
S 11/12/2003
S 4/20/2012
S 11/1/2012
Number of Number of
Constituent Result (mg/L) Flag Samples Detects
cis-l,2-DICHLOROET 4.8E+00 2 2
cis-l,2-DICHLOROET 3.3E+00 1 1
cis-l,2-DICHLOROET 4.3E+00 4 4
cis-l,2-DICHLOROET 4.1E+00 3 3
cis-l,2-DICHLOROET 3.0E+00 2 2
cis-l,2-DICHLOROET 6.7E-02 1 1
cis-l,2-DICHLOROET 2.9E-01 1 1
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 1 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
Well
Well
Type
Effective
Date
Constituent
Result (mg/L) Flag
Number of Number of
Samples Detects
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 2 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well:
Well Type:
COC:
2 0&-01 -
1.8&-01 -
_J ' '*"-' w '
o) 1 4FH.ni .
o
Q
01
O
MW102
S
cis-l,2-DICHLOROETHYLENE
User Name: MV
State: Montana
Time Period: 9/22/1998 to 11/1/2012
Consolidation Period: No Time Consolidation
Duplicate Consolidation: Median
Consolidation Type: Average
ND Values: 1/2 Detection Limit
J Flag Values: Actual Value
Date
«
+
* *
*
* *
******
Mann Kendall S Statistic:
1
Confidence in Trend:
50.0%
Coefficient of Variation:
1.21
Mann Kendall
Concentration Trend: (See
Note)
NT
Data Table:
Well
MW102
MW102
MW102
MW102
MW102
MW102
MW102
MW102
MW102
Well Effective
Type Date
S 2/6/2002 cis-1
S 8/16/2002 cis-1
S 6/13/2003 cis-1
S 11/12/2003 cis-1
S 5/26/2004 cis-1
S 10/15/2004 cis-1
S 4/28/2005 cis-1
S 10/27/2005 cis-1
S 4/6/2006 cis-1
Constituent
,2-DICHLOROET
,2-DICHLOROET
,2-DICHLOROET
,2-DICHLOROET
,2-DICHLOROET
,2-DICHLOROET
,2-DICHLOROET
,2-DICHLOROET
,2-DICHLOROET
Number of Number of
Result (mg/L) Flag Samples Detects
2.4E-02 1 1
1.3E+00 1 1
5.1E-01 1 1
2.2E-01 1 1
1.7E+00 1 1
6.4E-01 1 1
1.2E+00 1 1
6.1E+00 1 1
4.5E+00 1 1
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 1 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well
MW102
MW102
MW102
MW102
MW102
MW102
MW102
MW102
MW102
MW102
MW102
MW102
MW102
MW102
Note: Increasing
Well
Type
S
s
S
s
s
s
s
s
s
s
s
s
s
s
Effective
Date
10/27/2006
4/4/2007
10/4/2007
4/17/2008
10/16/2008
4/15/2009
10/8/2009
4/14/2010
10/14/2010
4/13/2011
10/13/2011
4/20/2012
9/7/2012
11/1/2012
User Name: MV
State: Montana
Constituent Result (mg/L) Flag
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
(1); Probably Increasing (PI); Stable (S); Probably Decreasing
(N/A) - Due to insufficient Data
1.9E+01
1.1E+01
5.1E+00
4.8E+00
8.7E+00
7.7E+00
3.4E+00
2.5E-01
2.8E+00
1.1E-01
9.8E-01
1.4E-01
5.8E+00
1.1E-01
(PD); Decreasing (D);
Number of
Samples
1
1
1
1
1
1
1
1
1
1
1
1
7
1
No Trend (NT); Not
Number of
Detects
1
1
1
1
1
1
1
1
1
1
1
1
7
1
Applicable
(< 4 sampling events); ND = Non-detect
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 2 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well:
Well Type:
COC:
o ec 01 -I
- 9 OF 01 -
E
r 1.5E-01 -
o
** 1 OF m -
Ol
o
c
o
01 OF n?
n nF+nn .
User Name: MV
State: Montana
MW117 Time Period: 1/1/2000 to 11/1/2012
T Consolidation Period: No Time Consolidation
cis-l,2-DICHLOROETHYLENE Duplicate Consolidation: Median
Consolidation Type: Average
ND Values: 1/2 Detection Limit
J Flag Values: Actual Value
Date
^
* 4
* - »
** .*
* » *
* »
Mann Kendall S Statistic:
42
Confidence in Trend:
87.5%
Coefficient of Variation:
0.67
Mann Kendall
Concentration Trend: (See
Note)
NT
Data Table:
Well
MW117
MW117
MW117
MW117
MW117
MW117
MW117
MW117
MW117
Well Effective
Type Date Constituent
T 8/16/2002 cis-l,2-DICHLOROET
T 10/31/2002 cis-l,2-DICHLOROET
T 6/13/2003 cis-l,2-DICHLOROET
T 11/12/2003 cis-l,2-DICHLOROET
T 5/26/2004 cis-l,2-DICHLOROET
T 10/15/2004 cis-l,2-DICHLOROET
T 4/28/2005 cis-l,2-DICHLOROET
T 10/27/2005 cis-l,2-DICHLOROET
T 4/6/2006 cis-l,2-DICHLOROET
Number of Number of
Result (mg/L) Flag Samples Detects
4.1E-02 1 1
6.3E-02 1 1
5.5E-02 1 1
4.0E-02 1 1
l.OE-01 1 1
5.4E-02 1 1
2.2E-02 1 1
2.6E-02 1 1
2.4E-02 1 1
MAROS Version 3.0
Release 352, September 2012
Tuesday, November 26, 2013
Page 1 of 2
-------
MAROS Mann-Kendall Statistics Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Well
MW117
MW117
MW117
MW117
MW117
MW117
MW117
MW117
MW117
MW117
MW117
MW117
MW117
Well
Type
T
T
T
T
T
T
T
T
T
T
T
T
T
Effective
Date
10/27/2006
4/4/2007
10/4/2007
4/17/2008
10/16/2008
4/15/2009
10/8/2009
4/14/2010
10/14/2010
4/13/2011
10/13/2011
4/20/2012
11/1/2012
Constituent
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
cis-l,2-DICHLOROET
User Name: MV
State: Montana
Result (mg/L) Flag
3.4E-02
1.2E-01
2.1E-01
1.7E-01
1.6E-01
7.5E-02
6.2E-02
4.1E-02
4.6E-02
5.0E-02
6.0E-02
9.9E-02
1.1E-01
Number of
Samples
1
1
1
1
1
1
1
1
1
1
3
1
1
Number of
Detects
1
1
1
1
1
1
1
1
1
1
3
1
1
MAROS Version 3.0
Release 352, September 2012
Tuesday, November 26, 2013
Page 2 of 2
-------
MAROS Spatial Moment Analysis Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Effective Date
Oth Moment
Estimated
Mass (Kg)
1st Moment (Center of Mass)
Xc(ft)
Yc(ft)
Source
Distance
User Name: MV
State: Montana
2nd Moment (Spread)
Sigma XX
(sqft)
Sigma YY (sq
ft)
Number of
Wells
7/1/2000
7/1/2001
7/1/2002
7/1/2003
7/1/2004
7/1/2005
7/1/2006
7/1/2007
7/1/2008
7/1/2009
7/1/2010
7/1/2011
7/1/2012
4.4E-01
5.8E-01
1.6E+00
1.6E+00
1.2E+00
9.5E-01
9.1E-01
9.2E-01
7.7E-01
9.9E-01
9.6E-01
9.5E-01
9.8E-01
681,191
681,196
681,243
681,229
681,226
681,224
681,255
681,241
681,245
681,234
681,224
681,230
681,212
173,460
173,452
173,455
173,467
173,474
173,469
173,452
173,474
173,463
173,462
173,475
173,471
173,511
305
296
264
282
288
287
252
279
268
274
291
283
326
6,050
6,282
11,497
11,842
11,892
12,825
16,834
11,832
11,218
11,167
10,878
9,943
7,617
5,985
6,015
19,214
19,690
18,367
18,992
22,772
19,667
18,803
17,522
17,454
17,357
15,907
10
11
34
32
32
27
26
25
25
25
25
25
32
7/1/2000
7/1/2001
7/1/2002
7/1/2003
7/1/2004
7/1/2005
7/1/2006
7/1/2007
7/1/2008
7/1/2009
7/1/2010
7/1/2011
7/1/2012
7.6E-01
8.2E-01
1.8E+00
1.4E+00
l.OE+00
9.6E-01
6.7E-01
8.5E-01
8.0E-01
9.4E-01
9.8E-01
1.1E+00
1.3E+00
681,181
681,187
681,213
681,196
681,205
681,197
681,195
681,210
681,210
681,212
681,206
681,212
681,211
173,467
173,454
173,482
173,504
173,489
173,492
173,510
173,502
173,501
173,492
173,499
173,494
173,505
316
304
304
331
314
321
337
320
319
312
321
313
322
5,394
6,378
7,293
5,444
5,026
4,424
5,667
5,130
5,362
4,017
3,844
3,933
3,623
5,000
5,440
16,312
14,620
13,200
11,275
13,675
12,963
12,466
10,323
10,696
10,687
11,656
10
11
34
32
32
27
26
25
25
25
25
25
32
7/1/2000
7/1/2001
7/1/2002
7/1/2003
1.8E-01
2.8E-01
5.1E-01
5.1E-01
681,183
681,207
681,203
681,198
173,449
173,423
173,471
173,476
304
269
303
310
5,444
6,439
7,367
7,034
6,194
6,598
15,891
16,752
10
11
34
32
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 1 of 3
-------
MAROS Spatial Moment Analysis Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
Effective Date
TRICHLOROETHYLENE
7/1/2004
7/1/2005
7/1/2006
7/1/2007
7/1/2008
7/1/2009
7/1/2010
7/1/2011
7/1/2012
Oth Moment
Estimated
Mass (Kg)
(TCE)
4.1E-01
3.6E-01
2.7E-01
3.2E-01
2.7E-01
2.4E-01
2.6E-01
2.3E-01
2.7E-01
1st Moment (Center of Mass)
Xc(ft)
681,192
681,199
681,201
681,224
681,220
681,216
681,217
681,230
681,214
Yc(ft)
173,487
173,471
173,481
173,465
173,464
173,468
173,470
173,468
173,493
Source
Distance
322
306
311
284
286
291
293
282
311
User Name: MV
State: Montana
2nd Moment (Spread)
Sigma XX
(sqft)
6,938
8,238
8,536
7,661
7,951
6,673
7,196
8,625
5,910
Sigma YY (sq
ft)
15,862
15,644
16,497
17,134
16,331
15,472
17,031
18,313
17,096
Number of
Wells
32
27
26
25
25
25
25
25
32
7/1/2000
7/1/2001
7/1/2002
7/1/2003
7/1/2004
7/1/2005
7/1/2006
7/1/2007
7/1/2008
7/1/2009
7/1/2010
7/1/2011
7/1/2012
7.4E-02
1.1E-01
1.6E-01
1.1E-01
8.9E-02
6.4E-02
6.9E-02
1.1E-01
8.4E-02
9.8E-02
8.2E-02
9.5E-02
5.2E-02
681,237
681,233
681,258
681,277
681,312
681,287
681,315
681,310
681,283
681,284
681,289
681,299
681,278
173,427
173,424
173,443
173,425
173,394
173,408
173,384
173,405
173,429
173,403
173,420
173,395
173,439
248
249
244
218
172
199
163
182
217
198
207
181
228
6,388
7,303
8,886
11,847
13,114
13,110
11,492
10,804
9,372
10,328
12,461
9,094
8,544
7,095
6,769
17,330
20,165
20,294
20,716
17,091
20,005
18,759
16,619
23,799
17,723
20,480
10
11
34
32
32
27
26
25
25
25
25
25
32
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 2 of 3
-------
MAROS Spatial Moment Analysis Summary
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
Moment Type
Oth Moment
Oth Moment
Oth Moment
Oth Moment
First Moment
First Moment
First Moment
First Moment
Second Moment X
Second Moment X
Second Moment X
Second Moment X
Second Moment Y
Second Moment Y
Second Moment Y
Second Moment Y
Constituent
cis-l,2-DICHLOROETHYLENE
TETRACHLOROETHYLENE(P
TRICHLOROETHYLENE (TCE)
VINYL CHLORIDE
cis-l,2-DICHLOROETHYLENE
TETRACHLOROETHYLENE(P
TRICHLOROETHYLENE (TCE)
VINYL CHLORIDE
cis-l,2-DICHLOROETHYLENE
TETRACHLOROETHYLENE(P
TRICHLOROETHYLENE (TCE)
VINYL CHLORIDE
cis-l,2-DICHLOROETHYLENE
TETRACHLOROETHYLENE(P
TRICHLOROETHYLENE (TCE)
VINYL CHLORIDE
Coefficient of Mann-Kendall S
Variation Statistic
0.35
0.29
0.33
0.30
0.07
0.03
0.05
0.14
0.27
0.21
0.13
0.21
0.30
0.28
0.26
0.29
6
12
-30
-18
-2
12
-4
-24
-10
-50
18
2
-12
-12
40
24
Confidence Moment
in Trend Trend
61.7%
74.5%
96.2%
84.7%
52.4%
74.5%
57.1%
91.8%
70.5%
99.9%
84.7%
52.4%
74.5%
74.5%
99.3%
91.8%
NT
NT
D
S
S
NT
S
PD
S
D
NT
NT
S
S
1
PI
Note: The Sigma XX and Sigma YY components are estimated using the given field coordinate system
with the estimated groundwater flow direction. Moments are not calculated for sample events with
and then rotated to
less than 6 wells.
align
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 3 of 3
-------
MAROS Zeroth Moment Analysis
Project: Lockwood Groundwater Solvent Plu User Name: MV
Location: OU2 State: Montana
Change in Dissolved Mass Over Time
COC: TETRACHLf
2.0E+00
1.8E+00
1.6E+00
1.4E+00
o) 1.2E+00
"^ 1.0E+00
| 8.0E-01
6.0E-01
4.0E-01
2.0E-01
O.OE+00
DROETHYLENE(PCE)
Date
^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
*
^ »
* * *
*
Porosity: 0.25
Saturated Thickness:
Uniform: 20ft
Mann-Kendall S Statistic:
12
Confidence in Trend:
74.5%
Coefficient of Variation:
0.29
Zeroth Moment Trend:
NT
Data Table:
Effective Date
7/1/2000
7/1/2001
7/1/2002
7/1/2003
7/1/2004
7/1/2005
7/1/2006
7/1/2007
7/1/2008
7/1/2009
7/1/2010
7/1/2011
7/1/2012
Constituent Estimated Mass (Kg) Number of Wells
TETRACHLOROETHYLENE(PCE) 7.6E-01 10
TETRACHLOROETHYLENE(PCE) 8.2E-01 11
TETRACHLOROETHYLENE(PCE) 1.8E+00 34
TETRACHLOROETHYLENE(PCE) 1.4E+00 32
TETRACHLOROETHYLENE(PCE) l.OE+00 32
TETRACHLOROETHYLENE(PCE) 9.6E-01 27
TETRACHLOROETHYLENE(PCE) 6.7E-01 26
TETRACHLOROETHYLENE(PCE) 8.5E-01 25
TETRACHLOROETHYLENE(PCE) 8.0E-01 25
TETRACHLOROETHYLENE(PCE) 9.4E-01 25
TETRACHLOROETHYLENE(PCE) 9.8E-01 25
TETRACHLOROETHYLENE(PCE) 1.1E+00 25
TETRACHLOROETHYLENE(PCE) 1.3E+00 32
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 1 of 1
-------
MAROS Zeroth Moment Analysis
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
Change in Dissolved Mass Over Time
COC: VINYL CHL(
1.8E-01
1.6E-01
1.4E-01
1.2E-01
* 1.0E-01
jg 8.0E-02
S 6.0E-02
4.0E-02
2.0E-02
O.OE+00
DRIDE
Date
^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
* *
*
Porosity: 0.25
Saturated Thickness:
Uniform: 20ft
Mann-Kendall S Statistic:
-18
Confidence in Trend:
84.7%
Coefficient of Variation:
0.30
Zeroth Moment Trend:
S
Data Table:
Effective Date
7/1/2000
7/1/2001
7/1/2002
7/1/2003
7/1/2004
7/1/2005
7/1/2006
7/1/2007
7/1/2008
7/1/2009
7/1/2010
7/1/2011
7/1/2012
Constituent
VINYL CHLORIDE
VINYL CHLORIDE
VINYL CHLORIDE
VINYL CHLORIDE
VINYL CHLORIDE
VINYL CHLORIDE
VINYL CHLORIDE
VINYL CHLORIDE
VINYL CHLORIDE
VINYL CHLORIDE
VINYL CHLORIDE
VINYL CHLORIDE
VINYL CHLORIDE
Estimated Mass (Kg) Number of Wells
7.4E-02 10
1.1E-01 11
1.6E-01 34
1.1E-01 32
8.9E-02 32
6.4E-02 27
6.9E-02 26
1.1E-01 25
8.4E-02 25
9.8E-02 25
8.2E-02 25
9.5E-02 25
5.2E-02 32
Monday, November 25, 2013
Page 1 of 1
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MAROS Percent of Mass by Well
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
ft
n
_TL
ft
MW002
MW003
MW004
MW005
MW006
MW007
MW008
MW009
MW010
MW011
MW017
MW100
MW101
MW102
5,645.55
11,391.98
12,075.99
19,665.29
15,763.45
7,413.01
11,096.51
6,746.82
5,572.92
1,117.38
5,445.13
445.41
1,523.14
1,322.97
0.25
3.89
42.74
430.69
18.21
2,438.88
406.83
613.96
0.83
175.20
0.95
0.02
2.89
0.93
0.00
0.06
0.62
6.20
0.26
35.10
5.86
8.84
0.01
2.52
0.01
0.00
0.04
0.01
2.69
5.43
5.75
9.37
7.51
3.53
5.29
3.21
2.65
0.53
2.59
0.21
0.73
0.63
Monday, November 25, 2013
Page 1 of 2
-------
MAROS Percent of Mass by Well
Project: Lockwood Groundwater Solvent Plu
Location: OU2
User Name: MV
State: Montana
rfb
MW103
MW104
MW105
MW115
MW116
MW117
MW121
MW122
MW123
MW124
MW125
MW126
MW127
MW128
PT-01
PT-02
PT-03
PT-04
PT-05
PT-06
PT-07
359.64
1,647.18
1,847.46
3,610.29
13,555.68
4,302.66
8,891.86
6,957.79
9,535.07
4,006.43
9,498.19
13,612.55
4,201.57
5,049.15
2,060.15
1,423.88
2,871.11
10,335.75
579.46
141.04
202.56
0.02
0.07
1.83
0.63
551.55
286.50
0.39
1,078.20
0.42
8.27
1.66
28.94
0.45
0.22
0.96
120.19
708.45
3.26
5.18
11.15
3.03
0.00
0.00
0.03
0.01
7.94
4.12
0.01
15.52
0.01
0.12
0.02
0.42
0.01
0.00
0.01
1.73
10.20
0.05
0.07
0.16
0.04
0.17
0.78
0.88
1.72
6.46
2.05
4.24
3.31
4.54
1.91
4.52
6.48
2.00
2.41
0.98
0.68
1.37
4.92
0.28
0.07
0.10
rfh
MAROS Version 3.0
Release 352, September 2012
Monday, November 25, 2013
Page 2 of 2
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