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Use of a Triad Strategy and On-site Gas Chromatography/Mass Spectrometry to Monitor the Performance of an In-Situ Electrical Resistance Heating Remediation System in a Non-Aqueous Phase Liquid Source Area at the Fort Lewis Logistics Center Superfund Site, WA

Triad Elements Used

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Table of Contents

  1. Site Information
  2. Project Information
  3. Triad Approach Information
  4. Supporting Information

At-a-Glance

Summary 

In 2004 the Fort Lewis Logistics Center Superfund Site used a Triad work strategy for performance monitoring associated with an in-situ electrical resistance heating (ERH) source remediation project for non-aqueous phase liquids (NAPLs). An on-site gas chromatograph/mass spectrometer (GC/MS) was used to produce air and water data within 24 hours of sample collection, and project data were posted to a website. The on-site GC/MS allowed for analysis of samples covering a large concentration range and was used for compliance (i.e., stack emission and reinjection criteria), operational, and performance monitoring. Off-site laboratories provided analyses of split samples and select primary samples. Data was reviewed daily by the project team, who made decisions regarding increasing, decreasing, or modifying the sampling and analysis strategy with the goal of providing the data required to control uncertainty as required for specific project decisions. Data quality requirements were assessed in relation to the specific data use.

1. Site Information

Site Name Fort Lewis Logistics Center, East Gate Disposal Yard (EGDY)
Location Tillicum, WA
Site Type  Disposal Pit
Site Regulatory ID  WA7210090067
Project Lead Organization Fort Lewis Public Works
Project Lead Type  U.S. Army Lead
Regulatory Lead Program  Superfund Remedial
Triad Project Status Field Program Completed
Reuse Objective Identified  Yes
Proposed Reuse:  Industrial with Land Use Controls

Background Information About Site 

Trichloroethene (TCE) was used as a degreasing agent at the Logistics Center until the mid-1970s, when its use was replaced with trichloroethane (TCA). Waste TCE was disposed of with waste oils at several locations. The EGDY was used between 1946 and the mid-1970s as a waste disposal site. Trenches were excavated in the yard and reportedly received TCE and petroleum, oils, and lubricants (POL) from cleaning and degreasing operations. This material was transported to the EGDY in barrels and vats from the various use areas. At times this material was used to assist in burning other waste products. In 2000, these trenches were opened and approximately 1,087 55-gallon drums, 92 35-gallon drums, and 1,285 5-gallon containers were removed from the EGDY. However, dense and light nonaqueous phase liquids (DNAPLs and LNAPLS, respectively) remain in the EGDY. The EGDY is the source area for widespread TCE contamination at the Fort Lewis Logistics Center. Soil and groundwater at the EGDY Site are contaminated primarily with chlorinated and nonchlorinated hydrocarbons, including TCE. TCE contamination exists in the subsurface as free-phase product, dissolved in groundwater, and adsorbed onto solids. The final engineering evaluation/cost analysis (EE/CA) for the EGDY and the Logistics Center at Fort Lewis recommended in-situ thermal technologies to remediate the free-phase product and optimization of the existing groundwater pump-and-treat system to remove remaining dissolved-phase contamination. The characterization of the disposal trenches at EGDY, which again applied the Triad approach, is discussed in another Triad Profile.

Fort Lewis incurred a large up-front cost (i.e., drum removal and thermal treatment of NAPL) to reduce source strength and reduce overall future life cycle costs by accelerating groundwater clean up. Thus, it was important that limited remediation funds be spent wisely and that data of sufficient quality were collected to evaluate the effectiveness of aggressive source treatment.

Contaminant(s) of Concern 

Contaminated Media 

Project Results and Outcomes 

The total mass collected from Area 1 during operations of the ERH remediation system was 2,576 kilograms of TCE, 405 kilograms of DCE and 40,171 kilograms of TPH. These totals consider mass recovered as vapors, dissolved phase, and NAPL process by the treatment system.

Contract specification temperatures were obtained in 193 (86 percent) of the 224 thermocouples monitored in Area 1 and 213 (95 percent) of these thermocouples reached the boiling point of TCE at depth. On average, thermocouples that reached design treatment temperature were maintained at that level for 70 days and those that reached the boiling point of TCE at depth were maintained at temperature for 97 days.

Vapor concentrations measured at the regional sampling ports and thermal oxidizer influent indicate that the recovery of vapor phase TCE across Area 1 peaked in early May 2004 and by mid July 2004 had reached asymptotic levels. There is no vapor data indicating that NAPL still exists in Area 1 or that continued heating in any portion of Area 1 would result in significant recovery of vapor phase TCE from the treatment volume.

Groundwater quality data showed that TCE concentrations in the treatment volume peaked as NAPL transitioned to the dissolved phase and then dropped to levels below starting concentrations. The highest groundwater concentration of TCE prior to heat-up was 1,500 micrograms per liter (µg/L) and the average was 383 µg/L. The highest groundwater concentration of TCE during treatment was 950,000 µg/L. The highest concentration of TCE in a groundwater monitoring well within the treatment area has now dropped to 220 µg/L as the treatment has progressed and the average concentration is 57 µg/L. Nine months of post treatment groundwater data indicates that groundwater concentrations are continuing to decline in Area 1.

2. Project Information

Project Objectives/Decisions 

The primary objective of the In-Situ Thermal Remediation system at EGDY was to maximize the removal of NAPL and associated volatile organic chemicals (VOCs) from three NAPL treatment areas (Areas 1, 2, and 3). The Triad-based adaptive site management remediation approach described in this profile focused on Area 1. The project objectives specified that the in situ thermal system, which utilized electrical resistance heating (ERH), must meet the following temperature and treatment duration requirements: 1) 100 degrees Celsius (C) in the saturated zone, 2) 90C in the vadose zone soil, 3) sustained temperatures at these levels for 60 days. As treatment progressed it became obvious that focusing energy input to try and achieve the initial performance objective of obtaining complete heating to boiling throughout the treatment area (i.e. >95 percent of temperature monitoring points meet or exceed temperature goals) was not the most effective strategy. The refined conceptual site model (CSM) developed as a result of treatment installation and operation data provided the team with a better understanding of contaminant distribution. In an effort to optimize treatment, the team decided to focus energy input to those areas of the site that contained relatively higher NAPL saturation.

In formulating the basis for system shutdown, the same lines of evidence that had been previously used to evaluate the extent and effectiveness of heating at individual temperature-monitoring points (TMPs) were used to evaluate the entire Area 1 treatment volume. Specifically, the system was evaluated by organizing all site data into the following four independent lines of evidence: 1) Is the TMP in an area where VOC concentrations are suspected to be high or low? 2) Has the subsurface surrounding the TMP reached an adequate temperature? 3) Have VOC concentrations in the subsurface adjacent to the TMP been reduced to the point of diminishing returns? 4) If heating is stopped, is there a risk that the area around the TMP could be recontaminated? The final treatment termination decision was made with input from the entire team, and the decision logic is documented in the attached NAPL Area 1 Completion Report.

Remedial Phase

Cleanup Design or Implementation

Triad Project Benefits 

Triad's emphasis on systematic planning to manage the full range of uncertainties (i.e. to clarify project goals and concerns through open discussion and documentation) creates an atmosphere conducive to trust and cooperative negotiations among all parties. If the technical issues are out in the open and stakeholders are assured that resource limitations and scientific uncertainties are being fairly balanced in relation to their concerns, there is a stronger foundation for negotiating parties to communicate over the more thorny and value-laden social issues. Specific benefits of utilizing the Triad to support an adaptive site management approach include the following:

Other specific benefits include the following:

Cost and Time Savings 

No formal cost comparison was performed; however, cost avoidance based on system optimization and reduced lag time between data collection and decision-making is expected to be significant.

3. Triad Approach Information

Systematic Project Planning 

Outputs of the initial systematic planning process at EGDY included: 1) consensus on the desired outcome (i.e., end goal) for the Site/project, 2) a preliminary CSM from existing information, 3) a list of the various regulatory, scientific and engineering decisions that must be made in order to achieve the desired outcome, 4) a list of the unknowns that stand in the way of making those decisions, 5) strategies to eliminate or "manage around" those unknowns, 6) explicit control over the greatest sources of uncertainty in environmental data (i.e., sampling-related variables such as sample volume and orientation, particle size, sampling density, sub sampling, etc.), and 7) "social capital" (i.e., an atmosphere of trust, open communication, and cooperation between parties working toward a protective, yet cost-effective resolution of the "problem"). All necessary decisions were defined along with the specific data necessary to manage the uncertainty associated with the various decisions.

The Remedial Action Management Plan (RAMP) was produced as a team effort among the Contractors, with USACE providing input and editorial comments throughout the draft development phases. A series of systematic planning meetings were implemented to present materials developed at milestones. The meetings provided a forum for discussion of project performance monitoring objectives.

Detailed tables that outline all data collection objectives and how the various types of data feed into each objective are included in the attached RAMP.

Project Team Description 

  1. Fort Lewis Public Works — Installation Restoration Program (IRP) Project Manager and project lead
  2. U.S. Environmental Protection Agency (EPA) — lead regulatory agency, supporting project team (Remedial Project Manager [RPM], hydrogeologists, thermal technical expert from the EPA Office of Research and Development [ORD])
  3. U.S. Army Corps of Engineers (USACE) — Primary project team (Project Manager, Environmental Scientist, Hydrogeologist, Chemical Engineer, Industrial Hygienist, Construction Quality Assurance Representative)
  4. Thermal Remediation Services — Primary project team (Project Manager, Contract Manager, Director of Operations, Quality Control [QC] Manager, Site Manager, Environmental Consultant, Hydrogeologist, Site Safety and Health Officer, Liquid Waste Management)
  5. Field Portable Analytical, Inc. — On site GC/MS Contractor
  6. Gary Struthers Associates — Construction and chemistry support
  7. AMEC — Data Management and Chemistry support
  8. CDM — Liquid waste management system design and support
  9. Army Environmental Center (AEC) — IRP Program Manager

Dynamic Work Strategies 

To evaluate the relative contribution of regional mass removal, the 106 multiphase electrodes in NAPL Area 1 were subdivided into six separately plumbed regions. The extracted vapors and liquids from each electrode region could be individually sampled. Other monitoring locations included thermocouple strings and monitoring wells within and outside the NAPL treatment area and at key locations within the above-ground treatment plant. With the flexibility of a dynamic sampling plan and an on-site laboratory with portable GC/MS, data anomalies were quickly confirmed, and sampling frequencies were altered as necessary to provide near real-time evaluation and observation of performance parameters for rapid decision-making.

Data collected during the system installation phase were used to refine the system design to enhance capture of previously unidentified NAPL areas and define the extent of NAPL outside the treatment area for possible follow-on remediation. System monitoring data were used to insure hydraulic containment goals, modify system extraction operations, and optimize treatment plant efficiency. The rate and total quantity of NAPL mass extraction as well as other dynamic decision parameters were used to determine when to terminate ERH due to declining mass removal. The use of a Triad work strategy that utilized near real-time analysis and a web-based data retrieval tool facilitated efficiency and optimization of this treatment method.

Data collected was stored in a project database and data was summarized in spreadsheets, graphs, plots and charts on a project website. Site operations reports, chemical quality control reports, and summary figures supported by data collected daily were posted to the website daily. Data not collected daily was posted to the website weekly. USACE used this information to determine if the project was meeting contract specifications, and as a platform to determine if changes to the protocols provided in the RAMP could maximize the efficiency of field operations and remediation system monitoring. Modifications to the SAP were addressed in weekly conference calls with the project team and USACE as part of a dynamic work plan process. Since an on-site laboratory was employed for most of the duration of operations, the preliminary analytical results for a groundwater or air sampling event were usually available within 24 hours on the project website.

Decision Logic 

A sampling/monitoring strategy was developed to address each objective in support of decision-making during treatment (see RAMP below). Specific data were required in order to make operation and performance assessment decisions. The ERH data collection program consisted of monitoring for contract performance, monitoring for system optimization, and monitoring for system performance. All necessary decisions were defined along with the specific data necessary to manage the uncertainty associated with the various decisions.

The ERH remediation system design included instrumentation and control systems that allowed for timely data acquisition, reporting, interpretation, and decision-making to verify that operational requirements were being met and to optimize each component of the remediation system. The instrumentation and website data management process ensured that the treatment progress was accurately tracked; the rate and volume of COCs removed were measured, and that system operations were in compliance with regulatory standards.

The initial contract performance goal was to increase the in-situ soil and groundwater temperature to a minimum of 100 C in the saturated zone and 90 C in the vadose zone. The contract required that these temperatures be reached at 95 percent of the temperature monitoring points. As treatment progressed it became obvious that focusing energy input to try and achieve the initial performance objective of obtaining complete heating to boiling throughout the treatment area was not the most effective strategy. The refined CSM developed as a result of treatment installation and operation data provided the team with a better understanding of contaminant distribution. In an effort to optimize treatment, the team decided to focus energy input to those areas of the site that contained relatively higher NAPL saturation. The team applied an adaptive site management approach and determined that the initial contract performance goals had been achieved, which was to maximize NAPL removal within Area 1, even though achievement of initial temperature goals at 95 percent of the thermocouples had not be obtained.

The modified decision-making protocol for evaluating the extent and effectiveness of heating at selected TMPs oriented around the four independent lines of evidence established for the Site:

  1. Is the TMP in an area where VOC concentrations are suspected to be high or low?
  2. Has the subsurface surrounding the TMP reached an adequate temperature?
  3. Have VOC concentrations in the subsurface adjacent to the TMP been reduced to the point of diminishing returns?
  4. If heating is stopped, is there a risk that the area around the TMP could be recontaminated?
The final treatment termination decision was made with input from the entire team, and the decision logic is documented in the attached NAPL Area 1 Completion Report.

Real-Time Measurement Technologies 

During monitoring well installation at locations outside the treatment area, soil samples were screened for both DNAPL and LNAPL. This field detection of NAPL was done using the following methods in a stepped approach. Visual observation was used first. If NAPL was not noted visually, a portion of the soil sample was screened with a PID and UV light. If there was a positive identification (ID) using the first three methods, then no further testing was done. If no NAPL was found using the above methods, further field screening for NAPL included a sheen test method and the "Oil-in-Soil" test kit.

To promote stability for a representative groundwater sample, field parameters including: temperature, pH, specific conductance, dissolved oxygen (DO), total dissolved solids (TDS), and oxidation-reduction potential (ORP) were measured using a flow cell while purging. The groundwater sample was collected after reaching stability and removing the flow cell from the tubing. The sample tubing was disposed of after sampling and was not reused for sampling another monitoring well.

Groundwater contours were posted daily on the project website to display hydraulic control from a water elevation perspective. Water levels in wells located outside the treatment area were obtained with a handheld water level indicator. Groundwater elevation data from within the treatment area was primarily obtained from vibrating-wire transducers and data loggers programmed to collect levels once every 12 hours. Before the treatment area reached temperature, water levels recorded by the vibrating wire transducers were also verified with a handheld water level meter. Once the subsurface had reached temperature, the casings containing the transducers were sealed and verification of transducer output with handheld meters became impossible.

Near-real time analytical data was provided by an on-site analytical service provider, Field Portable Analytical, Inc. (FPA); and an off-site (fixed) laboratory, Columbia Analytical Services, Inc. (CAS), provided analytical data for samples that required extremely low detection limits, target analytes other than target VOCs or other special handling. CAS also analyzed split samples selected to evaluate on-site laboratory performance, or to answer specific uncertainties associated with the evolving CSM that arose based on data generated by FPA.

The monitoring frequency and location was discussed and modified by the project team on a weekly basis.

Technology Category(s) for Sampling and Analysis 

Specific Technology(s)/Model Used (e.g., SCAPs) 

Technology Vendor(s)

Attached Technology Quick Reference Sheet (TQRS) Form 

TQRS pending


Data Quality Assessment 

Field QC began with a rigorous standardization protocol such that the field data were reported in an identical manner regardless of the sample location, sampling time, or sampler. The data were entered into the project database, and electronic and original field sheet data were compared to assure consistency and accuracy.

Analytical data from the on-site and off-site laboratories was subjected to several iterations of data quality review. The initial, preliminary review was conducted on-site by the Field Chemical QC Officer and was later reviewed in final format by the Project Chemist. Air and water samples collected from the Fort Lewis EGDY were analyzed for VOCs and TPH by the on-site laboratory, while off-site laboratories provided analyses of split samples and select primary samples. Data quality review was performed on a monthly basis and documented in the form of Data Quality Review (DQR) Reports posted to the project website. The data quality reviews did not include review or validation of raw analytical data from the on-site laboratory. The Field Chemical QC Officer generated Daily Chemical Data Quality Control (DC/DQC) Reports and Preliminary Data Review (PDR) Reports based on review of raw analytical data from the on-site laboratory.

The data quality indicators of precision, accuracy, representativeness, comparability and completeness were assessed by the following data QC parameters: daily calibration checks; method blanks, trip blank and purge blanks; surrogate spikes; matrix spikes and matrix spike duplicates (water samples only); laboratory and field duplicates; interlaboratory split samples; and performance evaluation samples.

There were 757 primary air samples and 749 primary water samples collected during operations. All air and water samples were analyzed within the QAPP recommended maximum holding time. The frequency of collection and analysis of field and laboratory QC samples met the QAPP requirements. Data quality review of data submitted by the off-site laboratories found all data to be fully usable without qualification. While data quality review of results generated by the on-site laboratory were found to be generally useable for the intended purpose of the data, results for approximately 32 percent of the air samples collected in one particular month were "J" qualified due to instrument calibration anomalies.

Data Management Approach and Tools 

Data management was a critical component of the EGDY project. Monitoring of the ERH remediation system was extensive, and in some cases data was recorded 24 hours a day. A project website contained daily, weekly and monthly reporting of data and analytical results. USACE used this information to determine if the project was meeting contract specifications, and as a platform to determine if changes to the protocols provided in the RAMP could maximize the efficiency of field operations and remediation system monitoring. The website data management process ensured that the treatment progress was accurately tracked; the rate and volume of COCs removed were measured, and that system operations were in compliance with regulatory standards.

All collected data, whether via electronic or manual means, was incorporated into the project geographic information system (GIS) database. The database was in the form of GIS/Key© Version 3.2. Prior to data transfer, field personnel performed a field comparison of the current day's data with the prior day's data to note any atypical measurements. A note was added to the current day's field log and daily activities report when atypical or unexpected measurements were recorded. The note(s) indicated the likely reason(s) for the atypical or unexpected measurement, and any planned adjustments to the system based on these measurements. If paper field forms were used, the on-site field personnel also performed a quality control review of the data entry to check for data transfer errors.

4. Supporting Information

Key Triad Project Milestones 

Dates of Operation - Field Work

Field work conducted December 17, 2003 to August 4, 2004

Source(s) of Information

Electronic Documentation of Supporting/Related Information

PDF Fort Lewis EGDY Final RAMP Data Management Plan (725 KB)
PDF Fort Lewis EGDY Final RAMP Workplan (5 MB)
PDF Fort Lewis EGDY Final Sampling and Analysis Plan (2 MB)
PDF Fort Lewis EGDY NAPL Area 1 Completion Report (24 MB)

Point(s) of Contact 

Kira Lynch
U.S. Army Corps of Engineers, Seattle District
4735 East Marginal Way South
Seattle, Washington  98134
Telephone icon 206-764-6918
E-mail icon kira.p.lynch@nwS02.usace.army.mil


Last Update:  06/01/2005

To update this profile, contact Cheryl T. Johnson at Johnson.Cheryl@epa.gov or (703) 603-9045.