EPA 542-R-14-006
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and
United States Technology Innovation
Environmental Protection
Agency
v>EPA
Optimization Review
Jones Road Superfund Site
Harris County, Texas
www.clu-in.org/optimizationl www.epa.gov/superfund/cleanup/postconstruction/optimize.htm
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EPA 542-R-14-006
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and
Technology Innovation
OPTIMIZATION REVIEW
JONES ROAD SUPERFUND SITE
HARRIS COUNTY, TEXAS
Report of the Optimization Review
Site Visit Conducted at the Jones Road Superfund Site
April 17, 2013
August 01, 2014
Revised 20 August 2014
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CONTENTS
Section Page
NOTICE iii
PREFACE iv
ACRONYMS AND ABBREVIATIONS v
EXECUTIVE SUMMARY ES-1
1.0 OBJECTIVES OF OPTIMIZATION REVIEW 1
2.0 OPTIMIZATION REVIEW TEAM 2
3.0 REMEDIAL ACTION OBJECTIVES AND SELECTED REMEDIES 3
3.1 Remedial Action Objectives and Affected Media 3
3.2 Selected Remedies 5
3.3 Potential Additional Remedies 6
4.0 FINDINGS 7
4.1 Data Gaps and Characterization 7
4.2 Remedial Strategy 8
5.0 RECOMMENDATIONS 11
5.1 Recommendations for SVE Remedy in Unsaturated Chicot Sand 11
5.2 Recommendations for SVE for Shallow Soil Treatment 12
5.3 Recommendations for ISB in Shallow WBZ 15
5.4 Recommendations for Lower Chicot WBZ 17
5.5 Recommendations for Data Management and Communication 19
5.6 Recommendations for Remedy Performance Monitoring 20
5.7 Recommendations for Remedy Exit Criteria 21
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Harris County, Texas
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TABLES
Table Page
1 Optimization Review Team 2
2 Other Optimization Review Contributors 2
3 Contaminants of Concern and Cleanup Goals 4
4 Affected or Potentially Affected Media on Site 4
5 Remedial Action Objectives as Stated in the ROD 5
6 Remedies Selected in the Record of Decision 6
7 Identified Data Gaps 7
8 Recommendation Summary 23
FIGURES
Figure Page
1 Site Location 1
2 Contaminant migration and potential exposure pathways at the Jones Road Site.
(Diagram not to scale) 3
3 Cross-section of mass distribution in shallow source soil. Majority of site mass is located in
Shallow Soil near and beneath shopping center 13
APPENDICES
A REFERENCES
B SUPPORTING FIGURES FROM EXISTING DOCUMENTS
C RECOMMENDED GROUNDWATER REMEDY PERFORMANCE MONITORING
PROGRAM
Jones Road Superfimd Site ii Optimization Review Report
Harris County, Texas
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NOTICE
Work described herein was performed by GSI Environmental Inc. (GSI) and Tetra Tech Inc. (Tetra Tech)
for and with contributions from the U.S. Environmental Protection Agency. Work conducted by GSI was
performed under Task Order 13-612/012 of EPA Contract EP-W-13-016. Work performed by Tetra Tech,
including final production of this report, was performed under work assignment (WA) 2-58 of EPA
Contract EP-W-07-078. Mention of trade names or commercial products does not constitute endorsement
or recommendation for use.
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 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 before they are implemented.
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PREFACE
This report was prepared as part of a national strategy to expand Superfund optimization practices from
site assessment to site completion implemented by the U.S. Environmental Protection Agency Office of
Superfund Remediation and Technology Innovation (OSRTI). The project contacts are as follows:
Organization
Key Contact
Contact Information
EPA Office of Superfund
Remediation and Technology
Innovation
(OSRTI)
Kirby Biggs
J OO
EPA OSRTI
Technology Innovation and Field Services
Division (TIFSD)
2777 Crystal Drive
Arlington, VA 22202
biggs.kirby@epa.gov
Phone: 703-823-3081
Environmental Management
Support, Inc. (EMS)
Abraham Parker
EMS
8601 Georgia Avenue
Suite 500
Silver Spring, MD 20910
abraham.parker@emsus.com
Phone:301-589-5318
GSI Environmental
(Contractor to EMS)
Mindy Vanderford, PhD
Mike Schofield
GSI Environmental, Inc.
2211 Norfolk
Suite 1000
Houston, TX 77098
mvanderford@gsi-net.com
Phone: 713-522-6300x186
mschofield@gsi-net.com
Phone:713-522-6300
Tetra Tech
(Contractor to EPA)
Jody Edwards, P.G.
Tetra Tech, Inc.
45610 Woodland Road
Suite 400
Sterling, VA 20166
iody.edwards@tetratech.com
Phone: 802-288-9485
Doug Sutton, PhD, P.E.
Tetra Tech, Inc.
2 Paragon Way
Freehold, NJ 07728
doug. sutton@tetratech. com
Phone: 732-409-0344
Jones Road Superfund Site
Harris County, Texas
Optimization Review Report
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ACRONYMS AND ABBREVIATIONS
3DVA Three-Dimensional Visualization and Analysis
(ig/L Micrograms per liter
AI Air Injection
bgs Below Ground Surface
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
COCs Contaminants of Concern
CPT Cone Penetrometer Testing
CSIA Compound-Specific Isotope Analysis
CSM Conceptual Site Model
cVOC Chlorinated Volatile Organic Compound
cis-1,2-DCE cis-1,2-Dichloroethene
DoD Department of Defense
DPT Direct-Push Technology
DQO Data Quality Objectives
EA EA Engineering, Science and Technology, Inc.
EPA U.S Environmental Protection Agency
ESD Explanation of Significant Differences
FS Feasibility Study
GAC Granular Activated Carbon
GC/MS Gas Chromatography/Mass Spectrometry
GIS Geographic Information System
Hapsite Hapsite Portable GC/MS Contaminant Identification System
HQ Headquarters
1C Institutional Control
ISB In Situ Bioremediation
MCL Maximum Contaminant Level
NAPL Non-aqueous Phase Liquid
ND Non-detect
NPL National Priorities List
O&M Operations and Maintenance
ORP Oxidation/Reduction Potential
OSRTI Office of Superfund Remediation and Technology Innovation
PCE Tetrachloroethene (Perchloroetheylene)
P&T Pump and Treat
QAPP Quality Assurance Project Plan
RAC Remedial Action Contractor
RAO Remedial Action Objective
RI Remedial Investigation
ROD Record of Decision
RPM Remedial Project Manager
SVE Soil Vapor Extraction
TCE Trichloroethene
TCEQ Texas Commission on Environmental Quality
trans-1,2 DCE fra«5-l,2-Dichloroethylene
VC Vinyl Chloride
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Harris County, Texas
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VI Vapor Intrusion
VOC Volatile Organic Compound
WBZ Water Bearing Zone
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EXECUTIVE SUMMARY
Optimization Background
The U.S. Environmental Protection Agency 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 are also encouraged to put
forth opportunities for the Agency to consider. "(1)
An optimization review considers the goals of the remedy, available site data, conceptual site model
(CSM), remedy performance, protectiveness, cost-effectiveness and 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 closure
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
Texas, 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).
1 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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Harris County, Texas
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Site-Specific Background
The Jones Road Ground Water Plume Superfund Site is located in western Harris County, Texas, just
outside of the city limits of Houston, Texas, in EPA Region 6. The site is the location of the former Bell
Dry Cleaners. The dry cleaning facility operated between 1988 and 2002 in a small shopping center in an
area of mixed commercial and residential land use. Releases of chlorinated volatile organic compounds
(cVOC) from improper disposal of dry cleaning solvents migrated vertically downward through the
unsaturated zone to perched water and to lower aquifers, where multiple private water supply wells were
and are presently located.
Land use surrounding the site was primarily agricultural prior to rapid suburban development in the 1960s
and 1970s. As part of the suburban and commercial development, many private water supply wells were
installed in the area. Tetrachloroethene (PCE) contamination was discovered in an area private water
supply well in 2000. Subsequent investigations identified leakage from dry cleaning operations at Bell
Dry Cleaners as the most likely source.
The site was added to the National Priorities List (NPL) on September 29, 2003, and remedial
investigation (RI) activities under the Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA) have been on-going since this time. The RI and feasibility study (FS) reports
were finalized in 2009, and a Record of Decision (ROD) was published in September 2010. The remedy
selected in the ROD includes an extensive groundwater extraction and treatment system (pump and treat -
P&T). Subsequent site data collection and cost estimates indicate that the selected remedy may not
provide an optimal approach to address site contamination. Remedial activities implemented since NPL
listing have focused on eliminating human exposure through the water ingestion pathway. Remedies to
date include extending municipal water supplies to properties with affected private water supply wells.
Approximately 51 percent of well owners chose to connect to municipal supplies. The site is currently in
the remedial design phase to address contamination in soil and groundwater.
Summary of Conceptual Site Model and Key Findings
Shallow surface soil below the shopping center is composed of dense clay, extending to a depth of
approximately 25 feet below ground surface (bgs). Area aquifers include the Chicot (ground surface to
approximately 400 feet bgs) and the Evangeline (below 400 feet bgs). A shallow, perched water-bearing
zone (Shallow WBZ) is located below the clay unit in the upper Chicot aquifer, with a saturated thickness
of 10 feet or less. Underlying the Shallow WBZ is an unsaturated clay (35 to 60 feet bgs) and an
unsaturated sand (60 to 110 feet bgs) (Unsaturated Chicot). The Lower Chicot aquifer is encountered at a
depth below 110 feet bgs and extends to a depth of approximately 400 feet bgs.
Based on contaminant concentration data and preliminary mass distribution estimates, the Shallow Soil (0
to 25 feet bgs) in the source area contains the majority of the site contaminant mass (estimated at 54
percent in the FS). Contaminant mass is concentrated in the area immediately under and behind the
former dry cleaners. The Shallow WBZ (25 to 35 feet bgs) is a thin, sandy, silty layer that may be
discontinuous in the region. The highest concentrations in the Shallow WBZ appear to be in the area of
monitoring well MW-01. However, it is unclear whether the full extent of Shallow WBZ contamination
has been delineated down- and cross-gradient.
The potential exists for vapor intrusion (VI) into indoor air in the commercial property because of the
high cVOC concentrations in the Shallow Soil and Shallow WBZ. While some preliminary vapor
assessments have been performed, the magnitude of VI impacts has not been fully characterized.
During the RI phase, an unsaturated zone in the Chicot unit (Unsaturated Chicot) was not fully identified.
From approximately 60 feet bgs to saturation at 110 feet bgs is a fine, unsaturated sand with relatively
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high vapor phase concentrations of PCE. The unsaturated zone has been identified by Region 6 as a
potentially important treatment area to cut off the transport of mass from the shallow source area to the
Lower ChicotWBZ.
The Shallow Soil, Shallow WBZ and the Unsaturated Chicot in the immediate area of the shopping center
east and just west of Jones Road contain the majority of contaminant mass. The optimization review team
has identified these media as priorities for remedial response based on the potential for continued
contribution of contamination to lower strata.
The primary remedy selected in the ROD is an extensive P&T system, which, in terms of mass removed
per dollar spent, does not appear to be highly effective or implementable. An in-situ bioremediation (ISB)
remedy using reducing amendments was selected for the Shallow WBZ in the ROD. A soil vapor
extraction remedy (SVE) has been proposed by both the EPA Region 6 Remedial Project Manager (RPM)
and the site optimization team to address contamination in the Unsaturated Chicot, which was not directly
addressed in the ROD. Uncertainties related to the selected ISB remedy include choosing an appropriate
amendment for the ISB and determining if metals such as arsenic and manganese may be mobilized as a
result of the changes in the oxidation/reduction potential (ORP). The primary uncertainty relating to the
SVE proposed for the Unsaturated Chicot is the efficacy of mass removal and the magnitude of long-term
releases of contaminants from the unsaturated clay layer.
The optimization review team finds that the Shallow Soil, the location of the majority of residual
contaminant mass, should be addressed by an aggressive remedy. Uncertainties and complications that
may influence the design of the Shallow Soil remedy include the density of the clay and the infrastructure
present on site. While excavation and thermal treatment may be appropriate for affected clay, the
presence and continued use of the building currently preclude these options. SVE is a possible alternative
remedy in the Shallow Soil, but questions remain about its efficacy in the dense clay.
The groundwater P&T remedy selected for the affected Shallow WBZ and Lower Chicot WBZ was
intended to address both hydraulic control and treatment. Historical evidence on P&T systems indicate
that these remedies are better suited to hydraulic control as they seldom achieve full treatment, so there is
some uncertainty about the ability of the selected remedy to attain cleanup goals. As noted above, the
extent of the plume in the Shallow WBZ may not be fully delineated. Additionally, groundwater flow
direction in the Lower Chicot WBZ can be and has been variable, depending on area pumping regimes.
Uncertainty about the direction of groundwater flow and the magnitude of groundwater withdrawal from
various depths confounds predictions about plume migration, and ultimately, about the risk of exposure
and the success of the remedy. As noted above, the cost of the remedy as selected relative to its ability to
attain remedial goals is in question. Because of the uncertainty about the hydrogeology of the Lower
Chicot WBZ, it is unclear if the extent of the plume has been fully delineated. Long-term management
and remediation of the Lower Chicot WBZ plume may require an optimized approach to P&T, aggressive
reduction of mass flux from the source, and additional monitoring locations.
The optimization review team finds that data gaps described above should be addressed for optimal
design of P&T systems for both the Shallow WBZ and Lower Chicot.
The optimization review team further finds that continued outreach to the community is appropriate
because of the continued possibility of human exposure to contaminants.
Data collection for the site has been ongoing since the mid- to late 1990s by multiple contractors and
regulatory entities. Much of the historical data have not been transferred to an electronic format suitable
for current data interpretation and visualization software. Integration of the full historical dataset into the
CSM is recommended because of the complexity of site hydrostratigraphy.
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Summary of Recommendations
A phased remedial approach is recommended for the site. The optimization review team recommends the
site remedial design include aggressive source treatment, which is anticipated to reduce volatile organic
compound (VOC) discharge to the Lower Chicot WBZ, supporting aquifer restoration in the lower plume.
Elements and priorities for the phased approach include:
Install an SVE system in the Unsaturated Chicot sand unit (60 to 110 feet bgs). A ROD
amendment is anticipated to initiate the process.
Delineate the extent of groundwater contamination in the Shallow WBZ. Evaluate whether more
extensive Shallow WBZ plume control is required.
Perform an SVE pilot for the Shallow Soil and, if successful, install a full SVE system in the
Shallow Soil to address the primary source of contaminant mass.
Develop a VI indoor air sampling protocol, considering some of the evolving protocols discussed
in Section 5.2.2. Sample indoor air before the SVE is installed as a baseline and, again, after soil
treatment to demonstrate conditions are protective for the indoor air exposure pathway.
Initiate ISB in high-concentration areas of Shallow WBZ; monitor groundwater concentration for
cVOCs and metals. Calculate mass flux response to remedy.
Measure groundwater levels and collect and analyze samples to determine contaminant
concentrations in the Lower Chicot WBZ before source area remedies are installed to establish a
current baseline. Monitor response of contaminant concentrations in existing Lower Chicot WBZ
wells (as well as the Shallow WBZ wells) after the SVE system and ISB remedy are installed in
the Upper Chicot.
A limited groundwater P&T system is recommended for the Lower Chicot and possibly the
Shallow WBZ near the source area (just east of Jones Road) to control plume migration. The
P&T system should be installed after SVE and ISB remedies in the source area, and after a period
of time sufficient to evaluate their efficacy. If the source treatments are effective at reducing mass
flux to the Lower Chicot and there are no identified secondary sources (for example, non-aqueous
phase liquid [NAPL]) in the Lower Chicot, the P&T system may be limited in scope or
eliminated.
Install extraction wells in the Shallow WBZ as a contingent remedy if SVE and ISB remedies do
not perform as anticipated or if more extensive shallow zone plume control is required.
Groundwater extracted from the Shallow WBZ can be treated with the P&T system, if required,
in the Lower Chicot WBZ.
No additional remedies are recommended at this time for the unsaturated clay underlying the
Shallow WBZ. The strength of the Unsaturated Chicot clay as a long-term source of contaminants
to the Lower Chicot will be determined by groundwater monitoring. A remedial approach may be
devised in the future to address clay as a secondary source.
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Area residents with private water supply wells in the Lower Chicot have been provided the
opportunity to connect to municipal water supplies. However, several members of the community
have opted not to connect to municipal water or have chosen to maintain their private wells as a
source of irrigation water. Outreach efforts are recommended to educate potentially affected
residents about the opportunities and rationale to connect to municipal water. Additionally, efforts
should be made to ensure that parties intending to purchase properties with affected water supply
wells are fully informed of the status of the groundwater supply.
There are several data gaps in the CSM for the Lower Chicot aquifer. Groundwater flow direction
and the effects of hydrostratigraphic heterogeneity on the flow regime are not well characterized.
The extent of contamination in the Lower Chicot is not well understood. However, the
optimization review team believes that characterizing and remediating media in the immediate
vicinity of the former dry cleaners (for example, the Shallow Soil, Shallow WBZ and Unsaturated
Chicot) should be the top priority of the site team. Additional characterization of deeper
groundwater should be considered after remedial components have been installed in areas of
highest residual contaminant mass. Future Lower Chicot aquifer characterization may include
installation of additional nested wells, optimally placed to assess groundwater flow direction and
contamination at various depths (for example, 150 to 200 feet bgs, 200 to 250 feet bgs, and 250 to
300 feet bgs).
Develop and continue to support electronic data management and visualization tools to document
and communicate remedy performance more rapidly and effectively. Consider performing
3-dimensional visualization and analysis (3DVA) to support interpretation and future monitoring
of plume distribution and dynamics, particularly in the Lower Chicot aquifer.
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1.0 OBJECTIVES OF OPTIMIZATION REVIEW
The Jones Road Ground Water Plume Superfund Site is located in western Harris County, Texas, just
outside of the city limits of Houston, Texas, in EPA Region 6 (See Figure 1). The Jones Road Site was
added to the National Priorities List (NPL) September 29, 2003, and remedial investigation (RI) activities
under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) have
been on-going since this time. The RI and feasibility study (FS) reports were finalized in 2009 (Shaw
2009a, 2009b) and a Record of Decision (ROD) was published in September 2010 (EPA 2010). The site
is currently in the remedial design phase.
For more than a decade, the U.S.
Environmental Protection Agency 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
Jones Road Site was nominated for an
optimization review at the request of the
Region 6 Remedial Project Manager (RPM)
in January 2013. The current review of the
remedy design proposed for Jones Road is
intended to optimize the remedial response
to address contamination in soil and
groundwater to achieve maximum
protectiveness while improving cost and
energy efficiency and minimizing time
required to attain cleanup goals.
Figure 1: Site Location
Excerpt from Figures 1 and 2 of the September 2010 ROD. Full
size versions of these figures are provided in Appendix B.
To this end, an optimization review team (described below) was assembled and met with regulatory
stakeholders and consultants in Dallas, Texas, and at the site near Houston, Texas, in April 2013 to
review site data, remediation goals, potential funding, and time frames to implement the remedy. This
report is a summary of the recommendations of the optimization review team based on a review of site
documents, the site visit, and meeting with stakeholders.
Objectives of the remedial design optimization review include:
Review of conceptual site model (CSM)
Review of Remedial Action Objectives (RAO)
Review of selected remedies, anticipated additional actions, and associated costs
Provide recommendations for remedial strategy, including:
o Addressing and prioritizing significant data gaps in the CSM
o Recommending remedy improvements, including new remedy components
o Prioritization and sequencing of 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
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Harris County, Texas
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2.0 OPTIMIZATION REVIEW TEAM
The optimization review team consisted of the independent, third-party participants listed below who
collaborated with representatives of EPA Headquarters (HQ) and EPA Region 6, the Texas
Commission on Environmental Quality (TCEQ), and representatives of EA Engineering, Science and
Technology, Inc. (EA), the Remedial Action Contractor (RAC) for EPA.
The independent (third-party) optimization review team consisted of the following individuals:
Table 1: Optimization Review Team
Name
Mindy Vanderford
Mike Schofield
Doug Sutton
Organization
GSI Environmental Inc.
GSI Environmental Inc.
Tetra Tech Inc.
Phone
713-522-6300
713-522-6300
732-409-0344
Email
mvanderfordigigsi-net.com
mschofield(g),gsi-net.com
doug.suttonigitetratech.com
The following individuals contributed to the optimization review process:
Table 2: Other Optimization Review Contributors
Name
Kirby Biggs
Tom Kady
Camille Hueni
Vincent Mallot
Marilyn Czimer Long
Buddy Henderson
Ted Telisak
Jay Snyder
Organization
EPAHQ
EPA HQ ERT
EPA Region 6
EPA Region 6
TCEQ
TCEQ
EA
EA
Title/Party
Optimization Review Lead
Optimization Review Team
RPM
Region 6 Optimization Liaison
Project Manager
Project Technical Support
RAC Project Manager
RAC Consultant
Present for Site
Visit/Site Meeting
Site Meeting
Site Meeting
Site Visit/Site Meeting
Site Meeting
Site Meeting
Site Meeting
Site Meeting
Site Meeting
A site visit was conducted by Camille Hueni from Region 6 and Mindy Vanderford and Mike Schofield
of GSI on April 17, 2013, in Harris County, Texas. A follow-up meeting with all of the participants
listed above was held at Region 6 Headquarters in Dallas, Texas, on April 23, 2013. Documents
reviewed during the optimization review process are listed in Appendix A.
This optimization review utilized existing environmental data to interpret the CSM, evaluate remedy
performance and make recommendations to improve the remedy. The quality of the 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 quality assurance project plan [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 evaluation or were used with the quality concerns noted. Where appropriate,
this report provides recommendations made to improve data quality.
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Harris County, Texas
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3.0 REMEDIAL ACTION OBJECTIVES AND SELECTED REMEDIES
The site is the location of a former dry cleaning facility. Releases of chlorinated volatile organic
compounds (cVOC) from improper disposal of dry cleaning solvents migrated vertically downward
through the unsaturated zone to perched water and to lower aquifers, where multiple private water
supply wells were and are located (see Figure 2). The current CSM is detailed in documents including
the ROD (EPA 2010), RI/FS (Shaw 2009a, 2009b, data evaluation summaries (EA 2011; EA 2012a)
and the Preliminary Design Report (EA 2012b). A summary of the CSM components relevant to
remedy design is provided below.
Figure 2: Contaminant migration and potential exposure pathways at the Jones Road Site.
(Diagram not to scale)
Direct contact
1
Shopping
Center
Parking Lot
Containment JZ^^B '/^^"\ Volatilization Indoor Air
Mass ' AP(1N/m=)AC(2')
SHALLOW CLAY
SHALLOW WBZ
I Discharge to GW
Groundwater Transport ^^^
W Discharge to Unsaturated Chicot
UNSATURATED CHICOT
-« VAPOR MIGRATION »-
1 Condensation of Vapors
j Discharge to Lower Chicot
SATURATED LOWER CHICOT
4
1
f
|
-^
j
I CLAY
\
\
\
Volatilization
AP(1 Hint1) AC(1')
/SAND
I
Volatiliza'tion to
Unsaturaled Zone
1
W Discharge to Evangeline Groundwater Transport ^^^
APPROXIMATE
THICKNESS
Drinking
water supply
3.1 Remedial Action Objectives and Affected Media
RAOs for the Jones Road Site have been developed to address contaminants of concern (COCs)
associated with the release of tetrachloroethene (PCE) from a dry cleaning operation located on site
(1988 to 2002). The basis for taking action at the site is that drinking water standards have been
exceeded in area private water wells screened in the Chicot Aquifer.
Area aquifers include the Chicot (ground surface to approximately 400 feet below ground surface [bgs]
and the Evangeline (below 400 feet bgs) (RI, Appendix C, Shaw 2009b). Depth to the Evangeline
increases from north to south across Harris County, ranging in thickness from 50 to 1,900 feet. The
Evangeline is separated from the Chicot by thin clay beds, but the delineation between the Chicot and
Evangeline zones is not well defined in the Jones Road Site area because of the lack of a marker bed.
Historically, many private and some municipal water supply wells drew water from the affected depths
of the Chico Aquifer. Most regional water supplies currently draw from the Evangeline or surface water
sources. Preliminary remedial activities at the site included providing area residents using private water
supply wells the option to connect to a municipal water supply and subsequently plugging the private
wells. Connection to municipal water was optional for the residents, and approximately half of the
residents chose to maintain their private supply wells. Filtration units were installed on private water
supplies and maintained by the state until municipal connections could be installed. The state is no
longer supporting and maintaining the filtration units. Consequently, the human health exposure
pathways of ingestion and dermal contact may still be open.
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Harris County, Texas
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No contamination has been detected in groundwater samples collected from the Lower
Chicot/Evangeline Aquifer interface (MW-17) to date (2008 most recent sample). At this time, no
information is available that suggests that the Evangeline aquifer is affected. An affected shallow
perched water-bearing zone is located approximately 25 to 35 feet bgs in the Upper Chicot Formation.
The perched saturated unit will be called the Shallow Chicot Water-Bearing Zone (WBZ) in this report.
The Shallow Chicot WBZ is not a current drinking water supply. The primary remedial concern for this
perched unit is that it may be an ongoing source of contamination to the underlying Lower Chicot
WBZ, a historical source of drinking and irrigation water classified as a potential drinking water source
by the state (Class I, water). Currently, area municipal water supply wells are screened in the deeper
Evangeline unit.
Site COCs and cleanup levels based on federal Maximum Contaminant Levels (MCLs) are shown in
Table 3. Affected and potentially affected media along with potential exposure and migration pathways
are summarized in Table 4 and depicted above in Figure 2. Table 5 lists RAOs for the source area and
downgradient groundwater.
Table 3: Contaminants of Concern and Cleanup Goals
Constituent Name
Tetrachloroethene (PCE)
Trichloroethene (TCE)
c/5-l,2-Dichlroethylene (cis-1,2 DCE)
fra«5-l,2-Dichloroethylene (trans- 1,2 DCE)
Vinyl chloride (VC)
Affected Media
Shallow and Lower
Chicot WBZ
Cleanup Goal
5(ig/L
5(ig/L
70 Mg/L
100 ng/L
2^ig/L
= micrograms per liter
Table 4: Affected or Potentially Affected Media on Site
Medium
Shallow Soil (Clay)
Shallow Chicot
Water-Bearing Zone
(WBZ)
Unsaturated Chicot
Location
Ground surface to
25 feet bgs
25 to 35 feet bgs
35 to 60 feet bgs
60 to 110 feet bgs
Composition
Dense clay to silty clay
Saturated fine to silty sand -
perched and likely
discontinuous
Clay to silty clay (35 to 60
feet bgs); sand (60 to 110
feet bgs)
Potential Exposure /
Migration Pathways
Discharge to underlying
shallow groundwater
(WBZ)
Direct exposure by
excavation
Not a drinking water
supply
Discharge downgradient
and to the underlying
Lower Chicot
Direct exposure by
excavation
Vapor phase discharge to
underlying Lower Chicot
aquifer
Jones Road Superfimd Site
Harris County, Texas
Optimization Review Report
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Medium
Saturated Lower
ChicotWBZ
Indoor air
Location
60 to 400 feet bgs
Commercial retail
building
Composition
Fine sand to well-graded
sand, occasional clay lenses
Slab on grade
Potential Exposure /
Migration Pathways
Private drinking water
supply
Discharge to deeper
Evangeline aquifer -
primary public water
supply
Inhalation risk-
volatilization from
shallow clay
bgs = below ground surface
Table 5: Remedial Action Objectives as Stated in the ROD
Site Area
Source Area
Deep Groundwater
Plume
Remedial Action Objective
Prevent future human exposure to contaminated groundwater at unacceptable
risk levels
Prevent or minimize further migration of contaminants from source materials to
groundwater (source control)
Prevent or minimize further migration of the contaminant plume (plume
containment)
Return groundwater to its expected beneficial uses whenever practicable (aquifer
restoration)
Prevent future human exposure to contaminated groundwater at unacceptable
risk levels
Prevent or minimize further migration of the contaminant plume (plume
containment)
Return groundwater to its expected beneficial uses whenever practicable (aquifer
restoration)
3.2
Selected Remedies
The remedy described in the ROD for the site includes a combination of groundwater extraction and
treatment (pump and treat - P&T) and in situ enhancements to stimulate contaminant mass destruction
in the source area (in situ bioremediation [ISB]) (see Table 6). The selected remedy also included
institutional controls (1C) for groundwater and indoor air sampling for vapor intrusion (VI) evaluation,
plugging water wells and supplying water service to properties with private groundwater wells screened
in the Lower Chicot WBZ.
In the ROD, the choice of in situ amendments included plans for a treatability study to evaluate the
most effective in situ treatment for the location and soil type. A pilot ISB injection test was conducted
in June 2012 (EA 2013a). Groundwater P&T from both the Shallow WBZ and the Lower Chicot WBZ
would address the RAO of containing the plumes and preventing further migration. The P&T remedy is
anticipated to include air stripping and vapor granular activated carbon (GAC) treatment before water is
reinjected to prevent issues with subsidence in the area.
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Harris County, Texas
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Table 6: Remedies Selected in the Record of Decision
Remedy
Hydraulic Containment /
Pump and Treat
In Situ Treatment
Plugging water supply
wells and water supply
connections
ICs
Groundwater monitoring
Indoor air investigation
Five-Year Reviews
Target Medium
Shallow WBZ source
area and Lower Chicot
WBZ
Shallow soil and
groundwater
Lower Chicot WBZ
Commercial property,
affected groundwater
Shallow WBZ and
Lower Chicot WBZ
Air inside commercial
building
All site media
Description
Pump groundwater (800 gallons per minute) from
both the shallow and deeper subsurface at a rate to
prevent further migration of contaminants -
estimated 420 million gallons per year
Eight extraction wells
Two treatment compounds
GAC vessels/air stripper
12 injection wells
Pre- and post-treatment for scale, pH and
fouling
(*Description from Remedial Design Report)
Treatment of soil and groundwater with
amendments that manipulate oxidation/reduction
environment in situ - amendments to be chosen
based on treatability studies
Plug residential and commercial water wells
penetrating the Chicot Aquifer for locations where
a water line has been supplied
Restrict excavation or drilling into affected
subsurface areas
Collection of contaminant concentration data to
assess remedy performance, progress toward
remedial goals and protectiveness
Sample air inside the commercial building under
varying weather conditions to assess the VI
exposure pathway
Reports to document remedy performance and
protectiveness
3.3
Potential Additional Remedies
During the RI phase, an unsaturated zone in the Lower Chicot was not fully identified. Therefore, the
presence of a potential vapor phase was not considered as a source in the evaluation of remedial options
or in the selection of a remedy in the ROD. Figure 2 illustrates the current understanding of the strata
underlying the site. At the start of the optimization review, a modification of the ROD was already
anticipated by Region 6 RPMs to include a soil vapor extraction (SVE) system to address the confirmed
contamination in this zone. A pilot SVE test in the Unsaturated Chicot Sand was conducted in January
2013(EA2013b).
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Harris County, Texas
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4.0 FINDINGS
This section outlines the major findings of the optimization review team.
4.1 Data Gaps and Characterization
During the site meeting and document review, several key data gaps and uncertainties in the Jones Road
Site CSM were identified. Perceived data gaps and a data quality objective (DQO) review of existing data
are discussed in detail in the Data Evaluation Summary Report (EA 2012a). Table 7 prioritizes data gaps
identified that may reduce the efficiency of remedial actions.
Table 7: Identified Data Gaps
Medium
Data Gap
Recommendation
Shallow WBZ
Extent of contamination in
Shallow WBZ
Delineate down- and cross-gradient extent of
contamination (proposed sampling locations are
detailed in Section 4.2).
Shallow WBZ
In Situ Bioremediation (ISB)
effects
Implement remedy, but monitor groundwater for
build-up of degradation products and mobilization of
metals.
Indoor air
commercial
building
Indoor air as a potentially
complete exposure pathway
Sample indoor air using passive sampler.
Unsaturated
Lower Chicot
Extent of contamination
Delineate horizontal extent of affected zone.
Lower Chicot
WBZ
Groundwater flow direction
at various depths, delineation
of contaminant
Monitor groundwater elevations and concentrations at
existing wells. Additional characterization may be
pursued after aggressive source treatment.
All lithologic
strata
Continuity and connectivity
of stratigraphic layers
Develop highly detailed boring logs for new
monitoring wells and remedial components. Develop a
comprehensive site database and geographic
information system (GIS) incorporating new site data
and historic data to the extent possible. Consider use
of 3- dimensional visualization and analysis (3DVA)
methods and tools going forward.
Affected groundwater in the Shallow WBZ is not delineated. The down- and cross-gradient extent of
contamination, particularly in the area of well MW-6, is not known. Lack of delineation in this zone
hinders estimation of total contaminant mass, area of affected media, and likelihood of mass migration to
other media. Similarly, the extent of contamination in the Unsaturated Lower Chicot Sand and Clay is
unknown. Estimates of total contaminant mass and affected area are required for both pre- and post-
remediation conditions to assess the efficacy of remedial efforts.
Groundwater flow direction in the Lower Chicot WBZ can be and has been variable, depending on area
pumping regimes. Uncertainty about the direction of groundwater flow and the magnitude of groundwater
withdrawal from various depths can confound predictions about plume migration.
Jones Road Superfimd Site
Harris County, Texas
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Questions remain for the ISB remedy selected for the Shallow WBZ as to whether amendments will result
in complete dehalogenation and whether reducing conditions will mobilize metals such as manganese and
arsenic from the subsurface. An additional concern is that vinyl chloride (VC) generated as a result of
biodegradation will present an excess risk to indoor air.
4.2 Remedial Strategy
The following CSM elements were found to be relevant to designing an optimal remedial approach.
Based on concentration data and preliminary mass distribution estimates (Shaw 2009a), the
Shallow Soil (0 to 25 feet bgs) in the source area contains the majority of site contaminant mass
(estimated 54 percent in the FS). Passive soil gas sampling results indicate that the majority of
contaminant mass is in the shallow subsurface immediately behind and beneath the former Bell
Cleaners building (see Figure 3). Sorbed mass can act as a long-term source to the dissolved
phase plume. Remedies to address sorbed mass in the source will, therefore, produce the greatest
long-term benefit to site cleanup.
The Unsaturated portion of the Chicot between approximately 35 and 60 feet bgs consists of
clay/silty clay similar to the Shallow Soil. However, from approximately 60 feet bgs to saturation
at 110 feet bgs is a fine, unsaturated sand with relatively high vapor phase concentrations
(130,000 micrograms per cubic meter PCE at SVE-2). The unsaturated zone has been identified
by Region 6 RPMs as a potentially important treatment area to cut off the transport of mass from
the shallow source area to the Lower Chicot WBZ.
The Shallow WBZ (25 to 35 feet bgs) is a thin, sandy, silty layer that may be discontinuous in the
region. Groundwater in this zone shows the highest concentrations in the area of MW-01, OB-01
and OB-02 downgradient to MW-06, where the plume appears to end abruptly or turns to the east.
The highest concentrations in the Shallow WBZ appear to be near monitoring well MW-01. It is
unclear whether the full extent of Shallow WBZ contamination has been delineated. Uncertainties
about contaminant mass transport in this zone may affect assessments of mass discharge to lower
strata.
A phased remedial approach is recommended for the Jones Road Site. Optimization review team
recommendations for the site remedial design include aggressive source treatment, which is anticipated to
reduce VOC discharge to the Lower Chicot WBZ, supporting aquifer restoration in the lower plume.
Remedial priorities and decision points are summarized here and described in detail in Section 5.
Install an SVE system in the Unsaturated Chicot sand unit (60 to 110 feet bgs). A ROD
amendment is anticipated to initiate the process. (An Explanation of Significant Differences
(ESD) or other ROD amendment is anticipated to select SVE as a remedy. Additional remedy
optimization recommendations may be included in the ESD at the discretion of Region 6 project
managers.)
Delineate the extent of groundwater contamination in the Shallow WBZ. Evaluate whether more
extensive shallow zone plume control is required.
Pilot test an SVE system in the Shallow Soil to address the primary source of contaminant mass.
If the pilot test is successful at removing contaminant mass, implement a full-scale SVE in the
Shallow Soil. While an SVE system for the Shallow Soil will most likely require a separate skid
and blower, some integration with the anticipated SVE system for the lower Unsaturated Chicot
Sand may result in cost savings.
Jones Road Superfimd Site 8 Optimization Review Report
Harris County, Texas
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Develop a VI sampling protocol to address indoor air inside the shopping center, considering
some of the evolving protocols discussed in Section 5.2.2. Sample indoor air before SVE is
installed and after soil treatment to demonstrate conditions are protective for the indoor air
exposure pathway.
Initiate ISB in high-concentration areas of Shallow WBZ; monitor groundwater concentration for
VOCs and metals and calculating mass flux response to remedy.
Measure groundwater levels and collect and analyze samples to determine contaminant
concentrations in the Lower Chicot WBZ before source area remedies are installed to establish a
current baseline. Monitor response of contaminant concentrations in existing Lower Chicot WBZ
wells (as well as the Shallow WBZ wells) after the SVE system and ISB remedy have been
installed in the upper Chicot.
A limited groundwater P&T system is recommended for the Lower Chicot and possibly the
Shallow WBZ near the source area (just east of Jones Road) to control plume migration. The
P&T system should be installed after SVE and ISB remedies in the source area and after a period
of time sufficient to evaluate their efficacy. If the source treatments are effective at reducing mass
flux to the Lower Chicot and there are no identified secondary sources (for example, non-aqueous
phase liquid [NAPL]) in the Lower Chicot, the P&T system may be limited in scope or
eliminated.
Install extraction wells for a P&T system in the Shallow WBZ as a contingent remedy if SVE and
ISB remedies do not perform as anticipated or if more extensive shallow zone plume control is
required. Groundwater extracted from the Shallow WBZ can be treated with the P&T system, if
required, in the Lower Chicot WBZ.
No additional remedies are recommended, at this time, for the unsaturated clay underlying the
Shallow WBZ. The strength of the Unsaturated Chicot clay as a long-term source of contaminants
to the Lower Chicot will be determined by groundwater monitoring. A remedial approach to
address secondary sources in the clay may be devised in the future. Groundwater monitoring data
will provide information on how to design and scale the remedy, if needed.
Area residents with private water supply wells in the Lower Chicot have been provided the
opportunity to connect to municipal water supplies. However, several members of the community
have opted not to connect to municipal water or have chosen to maintain their private wells as a
source of irrigation water. Outreach efforts are recommended to educate potentially affected
residents about the opportunities and rationale to connect to municipal water. Additionally, efforts
should be made to ensure that parties intending to purchase properties with affected water supply
wells are fully informed of the status of the groundwater supply.
There are several data gaps in the CSM for the Lower Chicot aquifer. Groundwater flow direction
and the effects of hydrostratigraphic heterogeneity on the flow regime are not well characterized.
The extent of contamination in the Lower Chicot is not well understood. However, the
optimization review team believes that characterizing and remediating media in the immediate
vicinity of the former dry cleaners (for example, the Shallow Soil, Shallow WBZ and Unsaturated
Chicot) should be the top priority of the site team. Additional characterization of deeper
groundwater should be considered after remedial components have been installed in areas of
highest residual contaminant mass. Future Lower Chicot aquifer characterization may include
installation of additional nested wells, optimally placed, to assess groundwater flow direction and
contamination at various depths (for example 150 to 200 feet bgs, 200 to 250 feet bgs, and 250 to
300 feet bgs). Installation of monitoring wells will address data site characterization and data
Jones Road Superfimd Site 9 Optimization Review Report
Harris County, Texas
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gaps while providing long-term monitoring locations for remedy performance assessment, plume
stability evaluations and demonstrations of protectiveness.
Develop and continue to support electronic data management and visualization tools to document
and communicate remedy performance more rapidly and effectively. Consider performing
3-dimensional visualization and analysis (3DVA) to support interpretation and future monitoring
of plume distribution and dynamics, particularly in the Lower Chicot aquifer.
Remedies common to all of the strata, both source and plume areas, include ICs, groundwater monitoring,
and preparation of Five-Year Reviews. These remedial components should be instituted as described in
the ROD.
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5.0 RECOMMENDATIONS
The recommendations provided by the optimization review team address the data gaps identified in
Section 4.1 and are consistent with the remedial strategy outlined in Section 4.2. The presentation of the
recommendations is consistent with the remedy prioritization and sequencing presented in Section 4.2.
Additional recommendations are provided for performance monitoring, data management and
development of exit criteria for each remedy component.
Relative to the ROD, the recommended strategy raises the priority of source remediation and emphasizes
performance monitoring and timely shutdown of remedy components. Collectively, the recommendations
help fill critical data gaps and satisfy the RAOs.
The primary "source" area refers to the immediate vicinity of the former Bell Dry Cleaners, including the
shopping center, alley, and parking area. The known affected source media include the Shallow Soil,
Shallow WBZ, Unsaturated Chicot, Sand and Clay and Lower Chicot WBZ east of Jones Road, and the
secondary source area refers to matrices slowly releasing contaminants immediately under and west of
Jones Road.
5.1 Recommendations for SVE Remedy in Unsaturated Chicot Sand
An SVE system is recommended to remove
contamination in situ in the Unsaturated Chicot Sand
(60 to 110 feet bgs). An SVE system has already been Recommendations
evaluated by EPA Region 6 RPMs, and the , ,. . . ... ,,
..... . ,& ... , . Reduce or eliminate mass discharge from
optimization review team agrees this approach is . T . . . . .r &
, , ,,, J.- i * o-iT-i- -i .L source to Lower Chicot Aquifer.
appropriate and should be prioritized. An SVE pilot
test was performed in this zone in January 2013.
Results of the pilot test indicate the approach is
appropriate and effective for this zone (EA 2013b).
. , _, . Reduce uncertainty about the location and
Treatment for the Unsaturated Chicot Sand was not £xtent of contammant mass m the
Benefits of Implementing Section 5.1
Reduce or eliminate need for extensive
P&T in Lower Chicot WBZ.
Unsaturated Chicot Sand.
listed in the ROD and will most likely require a ROD
amendment. Delineation of contamination in this zone
will support evaluations of remedy performance for
this area and will provide a better estimate of total contaminant mass that may be discharging to the lower
saturated zone.
The clay interval, located 30 to 60 feet bgs, presents several remedial challenges. Because of the density
of infrastructure in the area and on-going use of the shopping center, thermal treatment and excavation are
not currently recommended. Treatment of the Shallow WBZ with ISB and treatment of the underlying
sandy layer of the unsaturated zone may reduce flux of contaminants to the Lower Chicot WBZ, but the
clay layer is anticipated to remain a long-term, low-level source of contamination. Long-term
groundwater monitoring of the Lower Chicot WBZ will provide data on the effect of vapor phase back-
diffusion from the Unsaturated Chicot clay and will help prioritize and scale potential future remedial
responses. Thermal treatment or excavation should be considered if the shopping center property is
demolished or redeveloped.
Recommendation 5.1.1: The optimization review team agrees that installation of an SVE system in the
Unsaturated Chicot Sand is a priority. Five SVE wells (SVE-01 - 05) and one deeper well (IW-01D) are
currently in place east of Jones Road under the immediate source area. The SVE treatment system can be
installed on property behind the shopping center, owned by the current shopping center owner.
Jones Road Superfimd Site 11 Optimization Review Report
Harris County, Texas
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Recommendation 5.1.2: In addition to the six SVE wells east of Jones Road, two to three vapor and
groundwater monitoring wells should be installed to a depth of approximately 130 feet bgs with screened
intervals from 90 to 130 feet bgs into the saturated zone (similar in construction to existing SVE-4; see
field boring log in Appendix B Figures) west of Jones Road. The unsaturated sand is present from
approximately 60 to 110 feet bgs, with the saturated Lower Chicot present below approximately 110 feet
bgs and unsaturated clay present above 60 feet bgs. The wells will be used to help delineate the extent of
contamination in the Unsaturated Chicot Sand and monitor remedy performance.
Locations of the new vapor and groundwater wells may be contingent on property access agreements with
landowners. (Note: if wells are installed through a contaminated zone of the Shallow Chicot WBZ plume,
the wells should be double cased to prevent vertical migration of COCs.) Preliminary suggestions for the
well locations include one well west of Jones Road near existing well MW-9. A second potential location
is west of Jones Road directly across from Barley Lane. A third location may be chosen based on access
and sampling results from the two other wells.
The primary remedial risk for SVE in the Unsaturated Chicot Sand is insufficient air supply in the Lower
Chicot. Insufficient air supply will be indicated by low recovery and development of vacuum conditions.
The likelihood of this remedial risk is low because of the depth and porosity of the sand zone. An
additional potential complication with SVE in this zone is re-saturation of this unit. Saturation of the
Unsaturated Chicot Sand could occur over a period of years with high precipitation or changes in recharge
caused by land redevelopment. Re-saturation is, however, not anticipated from current discharge levels
from the Shallow WBZ.
A preliminary cost estimate for installation of SVE in the Unsaturated Chicot Sand is $150,000 for three
new wells, and design and construction of connecting piping, a blower skid (estimate 7.5 horsepower)
with moisture separator, and GAC treatment and controls in a fenced compound. Annual operating and
maintenance, including monthly system checks, quarterly sampling and analysis, GAC change-outs,
power and annual reporting, would be approximately $40,000.
5.2 Recommendations for SVE for Shallow Soil Treatment
SVE is recommended for the shallow clay soil in the area
immediately behind and beneath the shopping center,
focusing on the area around the SVE-01. Although the
Shallow Soil has fairly low permeability, SVE may be a
viable remedy in the limited area of highest contaminant
mass (see Figure 3). Based on the continued use of the
shopping center and the limited access to the area of high
contamination (in an alley behind the shopping center
and below the building), excavation or thermal treatment
are not practical. SVE may not fully remediate
contamination in this zone, but would serve to address an
area of highest residual contaminant mass and, therefore,
limit migration to the Shallow WBZ, indoor air and deeper strata.
An SVE system is anticipated by both the site and optimization review teams for the Unsaturated Chicot
Sand (60 to 110 feet bgs). (Note: the Unsaturated Chicot Clay layer [30 to 60 feet bgs] is not
recommended for SVE.) Extending the SVE system to the Shallow Soil in the area of highest contaminant
mass, or installing a separate system with a higher vacuum blower, if necessary, is technically
straightforward and can be accomplished at low cost. SVE is anticipated to address the potential VI
exposure pathway for the commercial buildings and capture some contamination that would otherwise
migrate vertically and laterally across the site. Shallow Soil SVE and Shallow WBZ ISB treatment, along
Benefits of Implementing Section 5.2
Recommendations
Focus remedy on area of highest
contaminant mass.
Reduce discharge of mass from
shallow soil to groundwater.
Address concerns about vapor
intrusion into existing building.
Jones Road Superfimd Site
Harris County, Texas
12
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with SVE in the Unsaturated Chicot Sand, are anticipated to cut off the majority of mass contributions
from the source area to the Lower Chicot WBZ. An BSD or other ROD amendment is anticipated prior to
implementation of the SVE system.
Recommendation 5.2.1: Pilot test an SVE system in the Shallow Soil source area in the vicinity of
SVE-01, behind the shopping center, near former boring GP-04. An illustration of the zone of high
contaminant mass to be targeted by the Shallow Soil SVE is provided in Figure 3. If the pilot test
demonstrates that an SVE system can effectively remove contaminant mass, design and install a Shallow
Soil SVE system to address contamination in the Shallow Soil.
Figure 3: Cross-section of mass distribution in shallow source soil. Majority of site mass is located
in Shallow Soil near and beneath shopping center.
North
A
130 r- 6MJ
MJ| GP-Zft GP-M
South
A'
B 30
j Slly CLAY (CL)
I CLAY (CH)
'.'?m.:i: :..:=!]» 1 inch = 20 ft
| PRELIMINARY |
H SILT |«L]
S«ND[£P)
**IGSI
ENVIRONMENTAL
fc, .M, « Q.303Q
3r' ::5-June-13
^'" As Shown
^'r-' DLB
'**' -'' MV
FIGURE 2
DISTRIBUTION OF PCE IN SHALLOW SOIL
Jons Road WPLSte
Hams Couniy. Texas
The additional system is anticipated to include four to five new SVE wells installed to a depth of
approximately 30 to 35 feet bgs, screened from the surface to 25 feet bgs in the alley behind the shopping
center, between existing wells MW-02 and MW-03. An air injection (AI) process is anticipated to be part
of the design, but precise design specifications will be developed by Region 6 and the Response Action
Contractor (RAC). SVE may have a limited area of influence in the clay of the Shallow Soil; therefore,
SVE wells may be placed more densely here than in more permeable strata. Remedy performance will be
measured by contaminant mass removal in the vapor effluent.
Assuming a separate blower skid will be needed, the optimization review team estimates that installation
of up to five shallow SVE wells and associated piping to convey extracted vapors to the separate SVE
treatment system will cost approximately $90,000 to $130,000. This cost would be in addition to the costs
for the Unsaturated Chicot Sand system and includes collocation and integration of controls. The
additional operations and maintenance (O&M) cost would be approximately $50,000 to $70,000 per year,
Jones Road Superfimd Site
Harris County, Texas
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depending on the power and equipment costs required to remove contaminants from the clay. More
accurate cost and performance estimates for the full-scale remedy can be refined after an initial pilot test
is performed. The overall capital cost could be reduced by approximately $40,000 and the O&M cost
reduced by approximately $10,000 per year if a common blower and treatment units could be used. The
cost of the pilot is estimated to be $30,000, including a week of tests and multiple vapor sample analyses.
Although the SVE system in the surficial clay unit may cost more and have a larger carbon footprint than
SVE in more porous soils, other remedy options are limited by the presence of the building and
infrastructure at the site.
Recommendation 5.2.2: VI is a potential exposure pathway at the Jones Road Site. Assessing the indoor
air exposure pathway for affected sites is an evolving practice from both technical and regulatory
perspectives. In addition to the 2002 EPA VI guidance (EPA 2002 #27), EPA is updating draft guidelines
for VI assessments (www.epa.gov/oswer/vaporintrusion). State guidance on VI varies widely (Eklund
2012 #26), with 42 states issuing draft or final guidance as of 2012. State guidance varies on the number
of times buildings must be tested as well as on the test methods and remedial approaches. The State of
Texas does not have VI guidance at this time. Additional complicating factors in VI assessment include
changes in screening levels.
Recent experimental results in animal tests have implicated trichloroethene (TCE) as a reproductive
toxicant, initiating a reduction in the protective exposure levels for indoor air. Finally, new technologies
in data collection, interpretation and management for VI investigations as well as remedial approaches for
affected buildings contribute to the evolving landscape for VI. As approaches to VI are changing rapidly,
the optimization review team recommends the following decision logic for addressing this exposure
pathway.
1. Compare groundwater concentrations with EPA-published screening criteria for VI assessment
(EPA 2002). As affected groundwater is shallow at the site and concentrations are high, the Jones
Road Site will likely require VI assessment.
2. Utilize distance-based screening criteria to identify potential buildings for VI assessment.
Typically, a 100-foot buffer around the groundwater plume is used for non-hydrocarbon VOCs.
3. Determine the investigation approach: VI investigation using vacuum SUMMA canisters with
sample collection rate regulators is a widely accepted approach to sampling sub-slab vapor and
indoor air. These samples provide a grab or time-weighted average exposure value. Investigations
using SUMMA canisters normally include collecting one to three sub-slab samples per building
(typically about one sample per 1,000 square feet), conducted before or along with indoor air
sampling and a background outdoor air sample. One drawback of indoor air sampling with
SUMMA canisters is that it does not distinguish between existing indoor and sub-slab vapor
sources. An additional concern is that VI can vary with time either seasonally or as a result of
other site conditions (for example, by building pressurization, where negative pressures can
enhance intrusion).
4. Determine if alternative approaches are applicable. For example, recent VI investigation methods
using a Hapsite Contaminant Identification System (Hapsite) instrument have been developed by
Department of Defense (DoD) stakeholders and approved by state regulators (McHugh, Beckley
et al. 2012) (GSI2013 #28). The Hapsite instrument is a portable gas chromatograph/mass
spectrometer (GC/MS) that provides direct, real-time data and precise locations of sources of
contamination. The Hapsite can positively identify multiple cVOC constituents (including PCE,
TCE and benzene) in real time and distinguish between indoor and VI sources. This feature
would be beneficial in distinguishing possible sources related to the hair and nail salon operations
in the shopping center and the automotive center operations next door from contamination that
Jones Road Superfimd Site 14 Optimization Review Report
Harris County, Texas
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originates in the subsurface. The Hapsite protocol includes pressure regulation within the building
to demonstrate cVOC concentrations under various pressurization scenarios to test the building's
susceptibility to VI. Data can be collected to target lines of evidence supporting regulatory
decision making.
5. Passive diffusion samplers can be used as a low-cost, preliminary screening tool to prioritize and
screen buildings or areas for more intensive investigations.
6. If indoor air is found to be affected above protective levels, several mitigation measures may be
implemented. The Shallow Soil SVE system may be modified to provide depressurization
(vacuum) on the soil vapor beneath the building along with sealing any slab penetrations or
defects. Heating, ventilation, and air conditioning systems may be modified. Choice of
appropriate mitigation is contingent on commercial activity, maintenance and property owner
considerations. Decision documents may need to be modified (through a ROD amendment or
Explanation of Significant Differences [ESD]) if an indoor air remedy is determined to be
necessary.
The cost of VI investigations would vary depending on the number of mobilizations, the number and size
of buildings investigated, and any complications arising from indoor and other sources. A preliminary
estimate of $30,000 is provided for planning purposes. This cost would cover installation of up to 12 sub-
slab vapor monitoring points and up to 30 vapor samples (sub-slab and indoor air) with analysis for VOCs
over two mobilizations including a brief work plan and report.
Recommendation 5.2.3: An additional and contingent Shallow Soil remedy should include excavation of
affected soil or thermal treatment. This remedy is recommended for consideration if the shopping center
is to be demolished or redeveloped. While extensive site redevelopment is not anticipated in the near
future, the option should be discussed if site redevelopment is pending.
5.3
Recommendations for ISB in Shallow WBZ
ISB treatment is the selected remedy for the higher
concentration Shallow WBZ area near the former dry
cleaners. The optimization team believes this is an
appropriate remedy for the Shallow WBZ. A pilot test
was conducted to evaluate the efficacy of ISB in June
2012 (EA 2013a). Overall, the results showed significant
decreases in dissolved VOC concentrations; however,
follow-up sampling was limited to a 6-month time frame
after amendment, so the dataset on potential
concentration rebound is limited.
Data gaps associated with this remedy include
uncertainty associated with mobilization of metals such
as manganese and arsenic and the extent of
dechlorination to non-toxic end products. An additional
concern is that VC generated as a result of
biodegradation will present an excess inhalation risk.
Benefits of Implementing Section 5.3
Recommendations
In situ destruction of contaminant
mass in the Shallow WBZ.
Limit migration of Shallow WBZ
plume and limit potential vertical
migration of contaminants.
ISB remedy has limited infrastructure
requirements and can be optimized
around amendment composition and
injection schedule.
A potential concern with ISB is
concentration rebound, given the high
concentration of COCs in the shallow
source clays. Long-term performance
monitoring is recommended.
Jones Road Superfimd Site
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Recommendation 5.3.1: Delineate the horizontal extent and continuity of contamination in the Shallow
WBZ. Delineation of contamination in this zone is recommended prior to initiation of ISB injections. A
combination of direct-push technology (DPT) sample delineation and installation of approximately three
new monitoring wells in the Shallow WBZ is recommended.
Depending on the sampling results at these locations, other sampling locations may be recommended to
complete delineation. Delineation may be performed using direct-push methods, but additional
monitoring wells are recommended for on-going remedy performance monitoring, plume stability
analysis and demonstrations of protectiveness. Detailed boring logs at sample locations will help address
uncertainty about the extent and connectivity of lithologic layers.
New monitoring well # 1 - cross-gradient to the east of centerline of plume, approximately 100
feet east and 50 feet north of MW-06. Direct-push methods can be used to identify the edge of
groundwater exceeding the MCLs and to select a precise location for a groundwater new
monitoring well. Samples at the new location should show low to non-detect levels of VOCs. The
new location should be sampled annually to biennially going forward to confirm delineation of
the plume. If samples show detections of cVOCs above MCLs, additional cross-gradient wells
may be necessary to delineate the extent of the plume. For locations above MCLs, sample wells
semi-annually to annually during active remediation to assess the efficacy of the remedy. Sample
annually to biennially after active remediation to assess long-term aquifer restoration.
New monitoring well # 2 - cross and downgradient east of MW-06, approximately 100 feet east
and 25 to 50 feet south of MW-06 in the grassy easement. This location is intended to help
delineate the downgradient edge of the plume to the southeast. The sampling frequency
recommendation is as above.
New monitoring well # 3 - cross and downgradient to the west of MW-06. Jones Road presents a
significant impediment to delineating the western edge of the Shallow plume. The new well
should be located across Jones Road, approximately parallel with the well recommended in the
bullet above and the well recommended for the Lower Chicot to monitor SVE performance. The
sampling frequency recommendation is also as above.
When measurement of groundwater levels in the monitoring wells has established groundwater
elevations in the area, complete delineation in the Shallow WBZ using direct-push methods and
high-resolution site characterization approaches.
The optimization review team estimates that delineation efforts in the Shallow WBZ should cost
approximately $30,000, depending on the number of DPT borings. The cost includes approximately
$10,000 for the three wells, $10,000 for 2 days of DPT boring installation, about 20 total samples with
VOC analysis, a brief work plan and report.
Recommendation 5.3.2: The optimization review team recommends that ISB treatments proceed after
delineation of the plume in the Shallow WBZ. Amendments should be injected in the general vicinity of
the pilot test. Delineation and monitoring efforts under Recommendation 5.3.1 will provide data to
estimate the full footprint, total dissolved mass and center of mass of the Shallow WBZ plume. If plume
delineation efforts indicate that the Shallow WBZ plume is significantly more extensive or mobile than
indicated in the RI/FS, selection and installation of the P&T remedy described in Recommendation 5.3.3
may be considered.
Jones Road Superfimd Site 16 Optimization Review Report
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Groundwater monitoring should be conducted on a quarterly to semi-annual basis at wells with detectable
concentrations after initiation of ISB to evaluate the performance of the remedy as well as formation of
degradation products and potential mobilization of metals in groundwater. Specific recommendations for
groundwater remedy performance monitoring are provided in Appendix C. Monitoring should continue at
least annually after the injection period to detect potential rebound of contaminants.
The optimization review team agrees with the site team that the initial injection for the ISB remedy can be
implemented with DPT injections based on the expected ease of implementation. Assuming the target
treatment zone is limited to a 100-foot by 200-foot area with 10 feet of saturated thickness, the remedy
might cost $500,000 for 66,000 pounds of emulsified vegetable oil diluted by more than 150,000 gallons
of potable water and approximately 30 days of two DPT rigs and crews to conduct the injections.
Recommendation 5.3.3: If ISB does not meet performance goals or if degradation products or metals
present excess risk, a Shallow WBZ P&T system is recommended be considered as a contingent remedy.
A P&T system has been proposed for the Lower Chicot WBZ (see Recommendation 5.4.2). The
optimization review team recommends that if the P&T system is installed in the Lower Chicot WBZ, the
system can be extended to the Shallow WBZ for long-term control of plume migration. The decision to
install a P&T system in the Shallow WBZ or continue with ISB injections could be based on the
performance of the ISB and the cost comparison of long-term treatment of the Shallow WBZ with each
technology. Treatment of the Shallow WBZ with P&T will be favorable if continued ISB will require
frequent injections or if ISB results in unacceptable impacts to water quality. Additionally, P&T would be
favorable for the Shallow WBZ if a Lower Chicot P&T system is installed and operating because the cost
of adding shallow extraction wells to an already existing system is relatively inexpensive.
5.4 Recommendations for Lower Chicot WBZ
The Lower Chicot WBZ is considered to be the depth I IT ~ ~ '. ~~~_ .
u 4. nn^^u j *i /innf *u Benefits of Implementing Section 5.4
between 110 feet bgs and approximately 400 feet bgs. _ r , _,.
, j J.- i / i + \ Recommendations
Below the initial source area (shopping center),
groundwater in the Lower Chicot shows dissolved
concentrations of PCE in the range of 200 micrograms
per liter (|ig/L). The combination of source removal and
treatments (SVE, ISB and, potentially, source P&T) is
anticipated to address the majority of contaminant mass discharge and promote aquifer restoration in the
Lower Chicot WBZ.
The remedy recommended for the Lower Chicot WBZ is groundwater P&T, similar to that described in
the ROD but limited to the area east of Jones Road beneath the source. The primary purpose of P&T in
this zone is to control migration of contamination, preventing mass from the source in the upper strata and
the plume in the Lower Chicot from discharging to potential drinking water supplies downgradient. The
P&T remedy should be designed and installed after the SVE and ISB remedies have been installed. The
remedial approach for the Lower Chicot WBZ is to eliminate mass discharge from the source area and
measure responses in the Lower Chicot WBZ to "right size" the long-term response to contamination in
this area. If groundwater concentrations in the Lower Chicot WBZ decrease in response to aggressive
source area treatment in the upper zones, the P&T remedy can be scaled appropriately to address a much
smaller plume footprint.
The area of the Lower Chicot plume downgradient from the source area is recommended for groundwater
monitoring from existing wells for a period of 5 years after the SVE/ISB remedies have been installed to
assess the efficacy of the source remedy.
Reduced cost and footprint relative to
the remedy selected in the ROD.
Jones Road Superfimd Site 17 Optimization Review Report
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After source removal efforts have been evaluated, additional characterization of the Lower Chicot may be
considered.
Recommendation 5.4.1: Monitor groundwater in the Lower Chicot WBZ at existing wells and new wells
recommended in Section 5.1.1 just west of Jones Road. A preliminary sampling event may be required in
the near term to establish baseline conditions prior to aggressive source area treatment. A comprehensive
sampling event prior to design of remedies (and preparation of the ROD amendment) will indicate
changes in plume morphology since the last sampling event (2008) and will guide design of the remedial
performance monitoring systems. After the SVE/ISB remedies have been installed in the source area, the
Lower Chicot WBZ should be carefully evaluated to assess plume response. If concentrations in the
Lower Chicot WBZ show statistically decreasing trends in the 3 years after SVE/ISB systems are
installed in the source, then reconsider or postpone installation of the P&T system. (Note: decision
documents may require amendment if the P&T remedy in the Lower Chicot WBZ is eliminated or altered
significantly.)
Comprehensive sampling of the Lower Chicot WBZ prior to source remedy design is anticipated to cost
approximately $20,000, depending on the number and availability of remaining private water supply
wells. This cost assumes up to 20 wells sampled in a 1-week period by a two-person team with analysis of
samples for cVOCs.
Recommendation 5.4.2: If Lower Chicot WBZ concentrations do not respond with stable to decreasing
statistical trends to source treatment, a limited P&T system is recommended for the Lower Chicot WBZ
in the area east of Jones Road. The treatment system should be designed to intercept the highest
concentration groundwater under the shopping center and Jones Road.
If groundwater data from the Lower Chicot WBZ indicate plume expansion (either vertically or laterally)
above MCLs, a more aggressive P&T system is recommended to control plume spread. Design of the
P&T remedy for the Lower Chicot WBZ is, therefore, contingent on the response to aggressive source
removal/treatment.
Risks to the P&T remedy performance include low mass removal and failure to control plume migration.
A cost-benefit analysis should be performed for the P&T system during the Five-Year Review. The
analysis should include estimates of the amount of mass removed relative to the cost of operating the
remedy. Monitoring delineation wells for detections of cVOCs and assessing individual well trends and
the distribution of plume mass will indicate plume migration. In the case of plume migration, a contingent
remedy may include changing the pumping regime or location of extraction wells.
Recommendation 5.4.3: A comprehensive monitoring and data analysis program along with supplied
municipal water and ICs is recommended for the downgradient plume in the Lower Chicot WBZ in the
medium term. The monitoring program will include annual sampling of existing wells installed in the
Lower Chicot WBZ, along with groundwater elevation measurements (at locations where possible) to
assess the overall plume attenuation rate. Groundwater data should be evaluated for statistical
concentration trends and estimates of total plume mass and center of mass over time. These analyses will
provide a measure of the stability of the plume. Additional geochemical analyses may provide improved
attenuation rates for contaminant mass in the Lower Chicot.
Continue monitoring elevation of groundwater in the Lower Chicot WBZ west of Jones Road.
Gaging water levels at private water wells may not be possible because of well construction and
pumping issues. The recommendation is to measure elevations before private supply wells are
plugged. Elevation may also be measured during pumping well maintenance such as replacement
of pumps. Monitor changes in elevation as private pumping wells are removed from service and
as the aquifer responds to changes in recharge caused by urbanization and climate variability.
Jones Road Superfimd Site 18 Optimization Review Report
Harris County, Texas
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Protectiveness of the aggressive source remedy should be evaluated during the Five-Year Review
process. If contaminant concentrations in Lower Chicot groundwater increase or there is evidence
of plume migration, a contingent remedy may include installation of the more extensive P&T
system described in the preliminary remedial design document (EA 2012b).
An additional consideration for documenting the rate of natural attenuation in the Lower Chicot
WBZ may include Compound-Specific Isotope Analysis (CSIA) of dissolved cVOCs. CSIA
evaluates the relative abundance of the heavy to light isotope ratios of carbon, chlorine or
hydrogen in specific cVOCs. Compounds that have been biodegraded tend to show higher ratios
of the heavier isotopes. CSIA has been used to provide evidence of contaminant destruction by
anaerobic microbial degradation. Efforts are currently under way to develop models, guidelines
and case studies for applying CSIA to demonstrate aerobic contaminant destruction through
cometabolism. CSIA may be considered at some point in the future for the Jones Road Site to
support development of appropriate degradation rates for the aerobic Lower Chicot groundwater.
At present, CSIA methods may not be fully developed and broadly accepted, but the optimization
review team believes that these tools may become more widespread in the next 5 years.
Area residents with private water supply wells in the Lower Chicot WBZ have been provided the
opportunity to connect to municipal water supplies. Several members of the community have
opted not to connect to municipal water or have chosen to maintain their private wells as a source
of irrigation water. Outreach efforts are recommended to educate potentially affected residents
and potential buyers of property about the opportunities and rationale to connect to municipal
water. If possible, there should be another round of connecting residents to municipal water
supplies and plugging private water wells. The optimization review team recommends
development of a fact sheet or webpage or holding a public meeting to motivate area residents to
connect to the municipal supply.
The Lower Chicot WBZ may require more extensive data collection and interpretation to support
future evaluations of progress toward remedial goals. As stated above, the focus of
recommendations in this report is to prioritize source treatment in the near term (the next 5 to 10
years) and evaluate the effect of source treatment in the downgradient Lower Chicot WBZ.
Future tasks related to the Lower Chicot WBZ might include monitoring program optimization
(to determine optimal placement of additional wells) and numerical modeling or 3DVA to track
and predict the plume morphology and progress toward remedial goals.
The optimization review team has not provided cost estimates for the staged approach to the Lower
Chicot WBZ, but believes that the reductions in the extraction system and treatment system relative to
what was described in the ROD will likely save more than $1 million in capital costs.
5.5 Recommendations for Data Management and Communication
Data collection has been on-going at the Jones Road Site
since the late 1990s, prior to widespread introduction of
computational tools to manage and evaluate environmental
data. The Jones Road Site extends over 350 acres and is
difficult to visualize without an integrated GIS. Simple, but
high-quality, data management systems are required to
store and retrieve data for concentration trend assessment,
mass quantification and mass flux assessments. Conversion
of historical site sampling data to database format will help
address outstanding data gaps.
Benefits of Implementing Section 5.5
Recommendations
Streamlined data management and
electronic visualization tools
communicate remedy performance
more rapidly and effectively.
Electronic data management
facilitates more sophisticated
statistical and performance
assessment methods.
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Recommendation 5.5.1: Several data management sub-tasks are recommended to improve archiving,
analysis, organization and communication of site data:
Creation of a site database containing sample identity, type and location information (sampling
location name; X, Y and Z coordinates; sample medium; types of samples collected; analyses
performed, and location of data results), analytical data (sample dates, analytes, concentration
results, detection limits, and data flags), and lithologic data (boring logs, cone penetrometer
testing [CPT] results, depth of observation, and type of geology). The database should prioritize
data collected during the remedial design and installation phase, but should include, to the extent
possible, data collected during the RI/FS stage, including CPT and DPT data, soil sample results,
and private water supply well locations and data. Some location coordinates may need to be
estimated from historical maps. Estimated data may be qualified in the site database to distinguish
them from more quantitatively determined data.
Creation of a GIS with all sampling locations (to the extent possible) and property ownership
boundaries, major roads, infrastructure, easements and municipal water supply wells.
Update the GIS with remedial components as they are installed. Update the site database with
sample results as they are confirmed to meet DQOs.
Produce maps and graphics with water wells and plume boundaries without the prominent
residential property boundaries to clarify the distribution of mass relative to the source.
Produce more detailed cross-sections including shallow zone lithologic details to the extent
possible.
Develop a data management and communication plan for stakeholders to support project and site
decision-making.
Recommendation 5.5.2: Consider performing 3DVA of the site, specifically the Lower Chicot aquifer.
The visualization can be performed using a variety of software tools, and the quality of the visualization
will improve as data gaps are addressed. The use of 3DVA would support an integrated analysis of plume
morphology and behavior as related to site geology and groundwater flow directions. 3DVA can also
function as a remediation performance monitoring tool to support decisions on design of the future P&T
or demonstrations of natural attenuation.
The cost of the initial 3DVA effort is anticipated to be in the range of $25,000 to $30,000, depending on
data quantity and organization. The cost of each subsequent groundwater monitoring update would be on
the order of $5,000.
5.6 Recommendations for Remedy
Performance Monitoring
Performance monitoring recommendations for each
of the remedies are described along with the remedies
above. Details of groundwater remedy performance
monitoring locations are located in Appendix C.
Additional recommended remedy performance
metrics include:
Benefits of Implementing Section 5.6
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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Estimate total sorbed mass in the source area and compare with mass removal by SVE.
Develop concentration vs. time (C vs. T) graphs for each of the groundwater monitoring locations
sampled. Historical data should be included in the C vs. T, and significant remedial events should
be noted.
Statistical trend tests should be performed for groundwater data and included in Five-Year
Reviews. Trend tests can be performed for datasets with four or more sample events. A non-
parametric test for trend, such as the Mann-Kendall test, is recommended to track groundwater
response to remedial actions. Semi-annual to annual sampling will generate datasets of sufficient
size to develop trends. Historical concentration data can be mined to determine the variability and
confidence intervals around concentration estimates.
A mass discharge or mass flux approach to assessing remedial performance can be effective in
demonstrating plume control and reduction in total mass (Farhat, Newell et al. 2006; ITRC 2010).
Initial mass estimates can be made using recent site characterization data. Mass flux calculations
can be performed during the Five-Year Review process and compared with pre-remedy estimates
to evaluate the efficacy of source treatment.
Estimate total dissolved mass in the Shallow and Lower Chicot WBZs from recent (2011 to 2013)
groundwater concentration data before remediation begins. Compare with estimates of dissolved
mass after source treatment.
Many software and analytical tools are available to evaluate trends and mass distribution in
groundwater plumes. Recommendations provided above are intended to guide discussion of more
specific remedy performance evaluation tools and methods. Each remedy and remedy stage
should have detailed DQOs, data management strategies, and a data analysis plan when the
remedies are designed.
Remedy performance monitoring cost estimates are estimated to be $30,000 per year, in addition to SVE
performance monitoring described in Sections 5.1 and 5.2 above. Remedy performance monitoring
involves routine groundwater sampling at Shallow and Lower Chicot WBZ groundwater wells, including
recommended new wells, and the analyses described above.
5.7 Recommendations for Remedy Exit Criteria
Establishing performance criteria for terminating each
remedy component can help reduce the risk of operating a
remedy past the point of effectiveness.
Recommendation 5.7.1: Exit (termination) criteria for each
remedy should be developed by the site team based on sound
scientific principles and site-specific remediation goals. To
assess remedy performance, special consideration should be
paid to the type of data required and the data management system supporting the analyses. The
optimization review team has the following suggestions listed by remedy for consideration by the site
team. The performance monitoring recommended in Section 5.6 and under each of the specific
recommendations above provides the necessary information to compare with the exit criteria.
Benefits of Implementing Section
5.7 Recommendations
Criteria to help avoid operating
long-term remedies longer than
necessary.
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SVE
o One potential exit criterion for the SVE system (or individual wells within the SVE
system) is a contaminant mass removal rate that is small relative to the initial mass
removal rate of the SVE system, such that continued operation of the system will result in
negligible mass removal relative to mass removal at startup.
o Another potential exit criterion for the SVE system can be based on a mass removal rate
relative to the current mass flux from the source area to the dissolved plume. Mass flux
can be measured using concentration data from groundwater wells MW-01, MW-01S and
recommended new wells.
o PCE vapor concentrations may rebound at particular locations after a vapor extraction
well is shut down as a result of back diffusion of mass out of tighter subsurface material.
Vapor extraction wells can be operated in pulse mode or on a rotating basis to extract the
accumulated vapors. If full rebound is persistent, contingent source remediation
alternatives may be pursued. Remedial system optimization may be considered if SVE
performance appears to diminish.
ISB
o An exit criterion for a source area saturated zone remedy could be based on
significantly reduced PCE concentrations and mass discharge at monitoring wells
MW-01 and MW-01S or response at MW-06. ISB can be discontinued when the
highest cVOC concentration in the most affected area of the Shallow WBZ is below
10 ug/L, as ISB below this level is not cost-effective. To evaluate if individual COC
concentrations are below the 10 ug/L cutoff, it is recommended that data from the
highest concentration wells for two years of sampling be evaluated to determine the
95% upper confidence limit (UCL). Remedy termination can occur if the 95% UCL
is at or below 10 ug/L. Upon termination of active ISB treatment, long-term
monitoring can be instituted to evaluate continued contaminant attenuation from
remaining microbial communities.
o Another potential exit criterion could be a determination that continued source area
remediation is providing no measurable additional benefit or is causing unacceptable
secondary water quality issues (for example, mobilization of metals or toxic
degradation products).
o PCE concentrations in the saturated zone may rebound at particular locations as a
result of back diffusion of mass out of surrounding clays once biological activity
ceases. Multiple reinjections are expected. If full rebound is persistent, contingent for
the remediation alternatives in the Shallow WBZ may be pursued.
P&T system for hydraulic plume control
o The exit criterion for a specific extraction zone within the P&T hydraulic control
remedy could be based on the PCE concentration and mass discharge at that
extraction zone relative to a predetermined threshold, below which unacceptable
plume migration will not occur.
Additional study by the site team would be needed to help define reasonable exit criteria for the various
remedy components to help avoid unnecessary operation of these remedies.
Jones Road Superfimd Site 22 Optimization Review Report
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The recommendations developed by the optimization review team are summarized in Table 8.
Table 8: Recommendation Summary
Recommendation
5.1.1 SVE system in the
Unsaturated Chicot Sand
5. 1.2 Additional Unsaturated
Chicot Sand and Lower Chicot
WBZ groundwater monitoring
locations to assess SVE
performance
5.2.1 SVE system in Shallow
Soil in source area (including
pilot)
5.2.2 VI assessment
5.2.3 Contingent source soil
excavation if property
redevelopment is anticipated
5.3.1 Delineate Shallow WBZ
groundwater plume
5.3.2 ISB treatment of Shallow
WBZ
5.3.3 Contingent P&T system
in Shallow WBZ if ISB
5.4.1 Monitor groundwater in
Lower Chicot WBZ at existing
wells for a baseline and
response to source treatment
5.4.2 Limited P&T system in
Lower Chicot WBZ east of
Jones Road
5.4.3 Monitor and characterize
downgradient Lower Chicot
WBZ west of Jones Road
5.5 Data Management and
Communication improvements
5.6 Remedy performance
monitoring
5.7 Considerations for exit
criteria for each remedy
component
Effectiveness
Cost Reduction
Technical
Improvement
Site Closure
Environmental
Footprint Reduction
Capital Cost
$190,000
$200,0000 -
$300,000
$30,000
(To be scoped as
contingency)
$30,000
$500,000
(To be scoped after
data gaps are
addressed)
$20,000
(To be scoped after
data gaps are
addressed)
Limited relative to
remedy cost
(Included in remedy
design)
Change in
Annual
Cost
$40,000
(See 5.6)
$50,000 -
$70,000
$10,000
(Cost
included in
5.6)
$30,000
Jones Road Superfimd Site
Harris County, Texas
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APPENDIX A
REFERENCES
Jones Road Superfimd Site Optimization Review Report
Harris County, Texas
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APPENDIX A
References
EA Engineering, Science and Technology, Inc. (EA) (2011). Data Evaluation Summary Report Jones
Road Ground Water Plume. Lewisville, EA Engineering for U.S. Environmental Protection
Agency Region 6.
EA (2012a). Data Evaluation Summary Report Jones Road Ground Water Plume. Lewisville, EA
Engineering for U.S. Environmental Protection Agency Region 6.
EA (2012b). Preliminary Design Jones Road Ground Water Plume Superfund Site Remedial Design.
Dallas, Texas, EA Engineering , Science and Technology, Inc. for US Environmental Protection
Agency Region 6.
EA (2013a). Injection Pilot Test Report Jones Road Ground Water Plume Superfund Site, EA
Engineering, Science and Technology, Inc. for EPA Region 6.
EA (2013b). Soil Vapor Extraction Pilot Test Report, EA Engineering, Science and Technology, Inc. for
EPA Region 9.
Eklund, B.; Beckley, L.; Yates, V. and McHugh, T. (2012). Overview of State Approaches to Vapor
Intrusion. Remediation, Autumn 2012, pp 7 -20.
Farhat, S. K., C. J. Newell, et al. (2006). Mass Flux Toolkit To Evaluate Groundwater Impacts,
Attenuation, and Remediation Alternatives. Battelle's Fifth International Conference on
Remediation of Chlorinated and Recalcitrant Compounds, Monterrey, CA, Battelle Press.
GSI Environmental Inc. (GSI) (2013). On-Site GC/MS Analysis Protocol for Vapor Intrusion
Investigations. Washington, D.C., GSI Environmental Inc. for Environmental Security
Technology Certification Program (ESTCP).
Interstate Technology Regulatory Council (ITRC) (2010). Use and Measurement of Mass Flux and Mass
Discharge, Interstate Technology Regulatory Council: 154.
McHugh, T. E., L. Beckley, D. Bailey, K. Gorder, E. Dettenmaier, I. Rivera-Duarte, S. M. Brock and I. C.
MacGregor (2012). "Evaluation of Vapor Intrusion Using Controlled Building Pressure."
Environmental Science & Technology 46: 4792-4799.
Shaw Environmental, Inc. (2009a). Feasibility Study Jones Road Groundwater Plume. Austin, Shaw
Environmental, Inc. for Texas Commission on Environmental Quality.
Shaw (2009b). Final Remedial Investigation Report Jones Road Groundwater Plume. Houston, TX,
Shaw Environmental, Inc. for Texas Commission on Environmental Quality.
U.S. Environmental Protection Agency (EPA) (2002). OSWER Draft Guidance for Evaluating the Vapor
Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion
Guidance), EPA 530-D-02-004.
EPA (2010). Record of Decision Jones Road Ground Water Plume Superfund Site. Dallas, TX, EPA
Region 6.
Jones Road Superfund Site A-l Optimization Review Report
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APPENDIX B
SUPPORTING FIGURES FROM EXISTING DOCUMENTS
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CYPRESS SHOPPING CENTER
Figure 1: Site Location
(Source: U.S. Environmental Protection Agency (EPA) (2010). Record of Decision, Jones
Road Ground Water Plume SuperfundSite. Dallas, TX, EPA Region 6)
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Direct contact
Majority of
Containment
Mass
(Shop
Get
r^T
SHALLOW
SHALLOW
ping
lter A Parking Lot
^~^\ Volatilization Indoor Air
AP (1 N/m2) AC (2°)
CLAY 1 Discharge to GW
WBZ Groundwater Transport ^^^-
W Discharge to Unsaturated Chicot
UNSATURATED CHICOT
-^ VAPOR MIGRATION ^^~
JL Condensation of Vapors
y Discharge to Lower Chicot
SATURATED LOWER CHICOT
\
1
1
[ CLAY
\
\
t ~5
Volatilization
AP (1 N/rri2) AC (1 °)
/SAND
4 !
| Volatilization to
Unsaturaied Zone
1
W Discharge to Evangeline Groundwater Transport ^^^-
-+
APPROXIMATE
DEPTH
25'
10'
25'
50'
Drinking
water supply
PRELIMINARY DRAFT
WIGSI
ENVIRONMENTAL
GSI Job No.:
G-3830
Issued:
13-Aug-13
Revised:
Scale: Not to Scale
Drawn by:
COM
Chk'd by:
MV
Aprv'd by:
Figure 2
CONTAMINANT MIGRATION OR POTENTIAL
EXPOSURE PATHWAYS
Jones Road Conceptual Site Model
Jones Road NPL Site
Harris County, Texas
-------
North
A
130 i-
110
90
CD
5 70
CO
CD
CO
CD
o
.Q
_
LLJ
50
30
10
-10
-30
GP-03
GP-5A
IW-02 IW-03
SVE-2
GP-06
GP-07
GP-6A
TD = 107.0 ft
<0.32
0.062
0.039
0.0024
TD =
48.0 ft
I
[
I
^^Wl ::
] < 0.01
c
J 1.9 f
. 1
1^707
J/.5
111 - -^^
I <0.012~~ -~
TD = 35.0 ft
1
f-
0.025
TD = 35.0 ft
TD = 127.0 ft
TD = 140.0ft
LEGEND
Silty CLAY (CL)
CLAY (CH)
Silty SAND (SM)
Clayey SAND (SC)
620 Tetrachloroethene (PCE)
concentration in soil (mg/kg)
Soil with PCE greater than 1 mg/kg
Horizontal Scale, ft.
0 7.5 15 22.5 30
I i i i i I | | |
Vertical Scale: 1 inch = 20 ft
Vertical Exaggeration: .75X
South
A1
i 130
110
90
CD
70 5
CO
CD
CO
CD
50
§
.Q
30 [2
_l
LLJ
10
-10
I -30
PRELIMINARY
SILT (ML)
1 Gravelly SAND (SW)
/
SAND (SP) 1 1 yiecuei man u iny/i\y
1 Soil with PCE 50 mg/kg
No Recovery FH soil with PCE too mg/kg
*j
<;si
ENVIRONMENTAL
GSIJobNo. G.3830
lssued 13-Aug-13
Revised:
scale As Shown
Drawn By: r-\i p>
Chk'd By: MV
Aprv'd By:
FIGURE 3
DISTRIBUTION OF PCE IN SHALLOW SOIL
Jones Road N PL Site
Harris County, Texas
-------
APPENDIX C
RECOMMENDED GROUNDWATER REMEDY PERFORMANCE MONITORING PROGRAM
Jones Road Superfimd Site Optimization Review Report
Harris County, Texas
-------
Appendix C:
Recommended Groundwater Remedy Performance Monitoring Program
Well Name
MW-01
MW-02
MW-03
MW-06
OB-01
OB-02
IW-01S
MW-04
MW-05
MW-07
MW-09
Additional wells to
delineate plume
MW-12
MW-13
MW-14
MW-15
MW-16
MW-18
Additional wells west
of Jones Road to
evaluate remedy
performance
MW-17
Remaining private
groundwater supply
wells
SVE extraction wells
(vapor)
SVE extraction wells
(vapor)
Unit
Shallow Chicot
WBZ
Shallow Chicot
WBZ
Shallow Chicot
WBZ
Lower Chicot
WBZ (261 to
300 feet bgs)
Lower Chicot/
Evangeline
interface (410 to
430 feet bgs)
Lower Chicot
WBZ (various
depths)
Shallow Soil
Unsaturated
Lower Chicot
Objective
Evaluate response
to ISB and source
area SVE
treatment
Delineate shallow
zone plume
Delineate shallow
zone plume or
evaluate mass in
plume
Evaluate plume
migration and
plume attenuation
Delineate plume
at depth
Evaluate plume
migration and
plume attenuation
Mass removal
Mass removal
Parameters and
Frequency*
VOCs and metals
quarterly for two years
during ISB and SVE
treatment, semi-annually
after remedies
VOCs annually
VOCs and metals semi-
annually for two years
during ISB and SVE
treatment and annually
thereafter
VOCs semiannually
after SVE is operational
VOCs annually
VOCs annually
Photoionization detector
monthly and VOCs
quarterly from key wells
for comparison
Photoionization detector
monthly and VOCs
quarterly from key wells
for comparison
Analyses
Concentration
Trend evaluation,
mass discharge
downgradient,
mass removal vs.
cost of remedy
Compare with
detection limits and
cleanup standards
Compare with
detection limits and
cleanup standards,
statistical trends
and estimate of
total dissolved
mass in unit
Concentration
Trend evaluation,
estimate of total
dissolved mass in
unit
Compare with
MCLs
Concentration
Trend evaluation,
estimate of total
dissolved mass in
unit
Mass removal rate
Mass removal rate
Jones Road Superfimd Site
Harris County, Texas
C-l
Optimization Review Report
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