The Wenatchee Tree Fruit Research and Extension Center (WTFREC) site is an agricultural research center in Wenatchee, Washington. A portion of the site was used as a pesticide disposal research area from 1966 until the early 1980s, resulting in soil contaminated with organochlorine, organophosphorus, and other pesticides. U.S. Army Corps of Engineers (USACE), in cooperation with U.S. Environmental Protection Agency (EPA) and the site owner, wished to clean up the site for residential reuse. The goal for the cleanup project was to identify, characterize, remove, and dispose of all pesticide-contaminated soil and debris present in the test plot area of the WTFREC. The action levels were determined to be the State of Washington Model Toxics Control Act (MTCA) Method B Cleanup Levels. USACE used a systematic plan with a dynamic work strategy guided by field analysis to integrate the site characterization and cleanup processes. Soil was characterized, excavated, and segregated based on immunoassay test kit results for dichlorodiphenyldichloroethane (DDT) and cyclodiene pesticides such as dieldrin and endrin. For the project, USACE developed a detailed statement of work (SOW) that outlined the on-site decision-making plan and specified the on-site measurement technologies to be used. In addition, a decision flow diagram was developed to guide the contractor through the on-site decision-making process. The cleanup was performed from September 1997 through January 1998.
|Site Name||Wenatchee Tree Fruit Research and Extension Center (WTFREC)|
|Site Type||Research and development facility|
|Project Lead Organization||USACE - Seattle District|
|Project Lead Type||U.S. Army Corps of Engineers Lead|
|Regulatory Lead Program||Voluntary Cleanup Program|
|Triad Project Status||Field Program Completed|
|Reuse Objective Identified||Yes|
The WTFREC was historically used as an agricultural research facility. From the mid-1960s to early 1980s, the U.S. Public Health Service and U.S. EPA used a 2,100 square foot test plot area at WTFREC for pesticide disposal testing. The approximate dimensions of the test plot were originally estimated as 70 ft by 30 ft, however, based on an evaluation of preliminary sampling results, the USACE concluded that lateral contamination extended beyond the edge of the test plot area. In the mid-1980s, the property was transferred from EPA to Washington State University (WSU). WSU operated test and laboratory facilities at the WTFREC and used the orchards as their primary research area. Nearby residential development was changing the land use pattern, increasing concerns that the test plot be remediated.
Between 1985 and 1987, WSU performed limited sampling and analysis of soil in and near the test plot. Additional site investigations were performed in 1990, 1991, and 1994. EPA obtained assistance from USACE for remediating the test plot site. The WTFREC site cleanup was performed under the regulatory oversight of the State of Washington’s Department of Ecology Voluntary Cleanup Program.
In 1997, the USACE implemented an integrated site characterization and remediation project at the site. This approach included characterization, excavation, and segregation of soil based on the results from rapid on-site analyses using commercially-available immunoassay (IA) testing products. A total of 271 samples were analyzed for this effort.
Pure pesticide products had been buried at two locations on the site. Initial cleanup activities included a focused removal of product in these 2 locations where 46 tons of soil and bagged pesticides were excavated for incineration. Area-wide site characterization to delineate less concentrated soil contamination was performed immediately following the pure pesticide removal effort. Samples were collected using a strategy that allowed an excavation plan and preliminary waste segregation/disposal plan to be developed. Gross removal activities involved excavation of 271 tons of soil, followed by an additional 60 tons excavated from sidewalls and floors. A total of 463 tons of material were used to backfill the site. Approximately two-thirds of the analyses performed during this effort used IA kits. Field and laboratory quality control (QC) samples were also analyzed during the project.
The goal for the cleanup project was to identify, characterize, remove, and dispose of all pesticide-contaminated soil and debris present in the pesticide test plot area of the WTFREC.
The use of systematic project planning, including up-front discussions among stakeholders and development of a conceptual site model, allowed the project team to develop a decision-making strategy that all parties would follow during the removal action. This reduced the amount of risk and cost associated with clean closure disagreements that can cause schedule delays. Substantial cost savings were realized through the use of IA and an adaptive sampling plan. Cost savings were realized through reduced analytical costs (compared with traditional fixed-based laboratory analysis), reduced volumes of contaminated soil requiring incineration or landfilling, and reduced mobilization/demobilization costs that would have been incurred if multiple mobilizations were required.
Characterization, cleanup, and closure were accomplished in a single 4-month field mobilization. The project cost of $589,000 was about half the $1.2 million estimated for a more traditional site characterization and remediation scenario. That scenario would have required multiple rounds of field mobilization, sampling, sample shipment, laboratory analysis, and data assessment. The dynamic approach resulted in substantial savings in the areas of soil analysis and waste transport and disposal.
The USACE and their contractor at this site planned acceptance and performance criteria for data collection, a Field Sampling Plan, and a Quality Assurance Project Plan (QAPP), based on the specifications in the Remedial Action Management Plan (RAMP). The planning followed the steps in EPA’s 7-part data quality objective (DQO) process. Planning and field teams were identified to facilitate the systematic project planning. The Planning Team consisted of representatives from EPA, the regulator (WA Department of Ecology), stakeholders (e.g., WSU), and USACE. The Field Team consisted of representatives from USACE, the prime contractor, and subcontractors.
An initial conceptual site model (CSM) was developed by the USACE based on a review of records and publications at the research facility and from contacts with WTRFEC researchers. The CSM included information about how the pesticides were disposed of at the site and the expected depth and lateral extent of pesticide migration in the soil.
As part of the DQO process, three decisions were identified for this site. The first was whether soil in exposure units (each of nine columns that the site was divided into) was contaminated at concentrations greater than the action levels established by MTCA for each contaminant of concern. The second decision was to determine if the remaining soil attained the cleanup standard, and the third was to determine the appropriate classification for disposal of excavated soil. The DQO process also was used to define the site boundaries, develop decision rules, specify limits on decision errors, and optimize the design for obtaining data.
USACE staff supporting the planning team effort included a project manager/team leader, a project chemist/scientist, a project engineer, an industrial hygienist, and a construction engineer. USACE staff supporting the field team effort included a project manager/team leader, a project chemist/scientist, a construction/project engineer, an industrial hygienist, and a field quality assurance [QA] officer.
USACE procured a prime contractor for the project (Garry Struthers Associates, Inc. [GSA]) using a pre-placed, indefinite-quantity, delivery order contract in August 1997. The contract was awarded based on evaluation of competitive bids from prospective contractors. The work was done under delivery orders that used a combination of fixed-price and fixed-unit price payment schedules. GSA provided a project manager, a field engineer, and a project chemist/QA officer. The prime contractor prepared the RAMP and oversaw several subcontractors, including one for soil sampling (Geoprobe work), three for analytical work, and one for transport and disposal of contaminated soil.
The USACE determined that site decisions could be made in the field, aided by the use of semi-quantitative data generated using on-site measurement technologies. They used an adaptive dynamic sampling strategy to support rapid location and definition of hot areas, guide the removal of contaminated soil, and quickly identify when sufficient information had been collected to address the remedial decisions.
In using this strategy, the test plot was divided into nine columns and three rows, making 27 sampling grids. A soil removal decision matrix was established for both shallow and deep burial columns, and statistical tests and decision errors were identified for final confirmation data. Field work was conducted in a dynamic manner by using the results from the DDT and cyclodiene IA test kits to determine where to perform excavations and when to identify the need for collection and analysis of confirmation samples.
The project team developed site-specific field action levels for the DDT and cyclodiene based on the results from an initial demonstration of method applicability. The team determined that a DDT test kit result of 5 milligrams per kilogram (mg/kg) could indicate that the site-specific cleanup level for an individual compound (e.g., DDT, DDE, or DDD) had been exceeded. Similarly, they determined that a cyclodiene test kit result of 0.086 mg/kg could indicate that the site-specific cleanup level for an individual compound (e.g., dieldrin or endrin) had been exceeded. By the end of the site characterization portion of the mobilization, additional pairs of test kit and fixed lab sample results established that the initial DDT kit field decision level was too conservative. Consequently with the approval of the regulator, the DDT IA field action level was raised to 10 mg/kg to guide the removal phase of the mobilization.
The real-time, adaptive decision matrix (see page 23 of the August 2000 published case study in the Electronic Resources list) guided field decisions based on contaminant distribution within six different depth intervals (12 inches per interval, ranging from 0-12 inches down to 60-72 inches). Decisions were based on the depth at which contamination was found in each sampling grid and directed the need for confirmation sampling based on the results of the field test kit analyses. For example, when the IA test kit results indicated contamination above the action levels in the 0-12 inch layer of a given grid element but not in the 12-24 inch layer, the decision matrix specified removal of the top foot of soil during the later excavation phase. Meanwhile, a split of the soil taken from the 12-24 inch layer was sent for fixed lab analysis. If the fixed lab results confirmed that the 12-24 inch layer was "clean," no further action was needed for that 10 ft x 11 ft grid element.
The USACE team developed site-specific action levels for the IA test kits based on results from a pilot test, which included a comparison of IA analytical results with those from a fixed laboratory. An initial demonstration of method applicability involving the IA method results and fixed laboratory results was completed before the SOW was finalized, and the demonstration results were incorporated into the systematic plan. The IA data were used to identify areas to be excavated and to confirm that contaminated soil had been removed.
Yes, please see the Case Study referenced below
Several QA/QC measures were implemented during sample collection and field and fixed laboratory analyses. Field sampling QC samples were collected during field work to monitor the performance of sample collection and measure the effects of sampling bias or variability. Field QC samples included equipment blanks and field duplicates. Field analytical QA/QC measures included use of calibration samples, negative controls, matrix duplicates, and laboratory control samples. Fixed laboratory QA/QC measures included use of continuing calibration verification compounds, internal standards, surrogates, method blanks, matrix spikes, matrix spike duplicates, laboratory control samples, and performance evaluation samples.
For the IA test kits, as reported in the technology quick reference sheet (TQRS), the precision achieved was assessed by analyzing a pair of duplicate samples with each of the batches of field samples. For DDT analyses, the relative percent difference for pairs from the 16 batches ranged from 0 to 113%, with a mean RPD of 38% and a median RPD of 28%. For cyclodienes, the relative percent difference for pairs from 14 batches ranged from 0 to 110%, with a mean RPD of 35% and a median RPD of 7%.
Information about specific data management tools was not provided.
|Cost and Performance Report – Expedited Characterization and Soil Remediation at the Test Plot Area, Wenatchee Tree Fruit Research Center. May 15, 2000. (1.1 MB)|
|Innovations in Site Characterization Case Study: Site Cleanup of the Wenatchee Tree Fruit Test Plot Site Using a Dynamic Work Plan. EPA-542-R-00-009. August 2000. (500 KB)|
|Remedial Action Management Plan – Wenatchee Tree Fruit Research Center Test Plot Remediation. August 1997. (111 KB)|
|Sampling and Analysis Plan, Field Sampling Plan – Part B (190 KB)|
|Sampling and Analysis Plan, Field Sampling Plan – Part C (155 KB)|
To update this profile, contact Cheryl T. Johnson at Johnson.Cheryl@epa.gov or (703) 603-9045.