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Soil Investigation

Soil sample collection

Soil sample preparation

Since 2001, Velsicol has spent nearly $1,000,000 to characterize the nature and extent of contamination along the creek and to determine if any cleanup was necessary. The following is a summary of the work that has been done so far.

The 2001 study was designed to fill-in data gaps from previous scientific studies and identify any areas of possible concern. This study was the first to analyze overbank soils along a 2.5 mile length of the creek in the predominantly residential area from Jackson Avenue, near the Velsicol manufacturing plant, to Evergreen Street. In addition, scientists took more soil samples than in any previous study and tested them for a broader range of chemicals. Between March and May 2001, a total of 53 soil samples were collected for analysis. Samples were also obtained from the creek channel and banks and in the undeveloped storm water storage areas in Sub-Area IV and Sub-Area V. Soil samples taken by Velsicol were generally from the soils surface to a 12-inch depth. Holes were drilled in the concrete liner in order to take samples in Sub-Area II.

An independent testing laboratory hired by Velsicol and the state's environmental laboratory analyzed the soil samples for a wide range of contaminants. All study data, including results from earlier studies, were then compared to EPA Preliminary Remediation Goals (PRGs), which are screening levels used to determine if additional investigation is required.

All five Sub-Areas had one or more chemicals that exceeded the screening levels, so all areas were carried into a more detailed preliminary risk evaluation. Consistent with the outcome of all studies since 1964, the 2001 study and preliminary risk evaluation did not indicate any imminent risk to public health.

In 2002, Velsicol focused its efforts on investigating the Cypress Middle School and University Park area, located in Sub-Area III. Scientists collected 30 samples and evaluated the contents. Toxicologists found no unacceptable imminent or long-term human health risks. "In an abundance of caution," TDEC elected to install a layer of clean soil over areas that had elevated contaminant levels. State officials also required posting of warning signs around Sub-Areas IV and V as a precautionary measure until the investigations are completed.

In 2003, Velsicol worked closely with TDEC and EPA to sample 84 properties along the creek. They represent about half of the properties in Sub-Area III. The samples were tested by approved laboratories. TDEC set a screening level of 0.7 parts per million of dieldrin, the main compound screened for that could potentially impact health. For most properties, only very low levels of contamination were found. In one-third of the cases, however, dieldrin was found in the soil above the state's screening level. This meant more testing was necessary to investigate soils at properties located adjacent to those with "elevated" contaminant levels. In March 2004, test results for individual properties were reported to landowners/residents.

Fifty additional properties were sampled, including properties adjacent to those above the screening level. At this point, 76 percent of the properties that back up to the creek have been sampled. Laboratory analyses were completed in November. Scientists and the U.S. EPA are reviewing the data to assure quality and accuracy for use in the risk assessment. In December 2004, test results for individual properties were reported to landowners/residents.

Velsicol also supported TDEC and EPA in testing soils in Sub-Area IV during June and July. This work included the collection of soil samples from 130 locations on a 100-foot grid. TDEC and EPA evaluated the test results and identified areas for additional soil sampling and testing.

As follow-up to the 2004 Sub-Area IV soil investigation, 48 additional soil samples were collected for testing during April 2005. Velsicol again supported TDEC and EPA’s work by way of mapping and sample collection. TDEC and EPA are evaluating these Sub-Area IV test results, with support from Velsicol. During August 2005, Velsicol collected and tested soil samples from six additional residential properties in Sub-Area III. The focus of this investigation was properties adjacent to previously tested properties where the dieldrin concentrations were found to be above three parts per million. The objective of this investigation was to determine if any properties adjacent to those where TDEC had directed Velsicol to perform soil removal based on an action level of three parts per million, would also warrant cleanup.

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