Two creeks cross the Exide property from east to west, including Stewart Creek, which runs along the south side of the former production area, and a tributary to Stewart Creek (the “North Tributary”), which runs along the north side of most of the former production area. Most of the former production area is located between Stewart Creek and the Northern Tributary. The North Tributary converges with Stewart Creek northwest of the former production/operation area.
Historic investigations indicate past operations at the Former Operating Plant resulted in contamination of some sediments in certain portions of the creek. Contaminated sediments in the section of Stewart Creek crossing the Former Operating Plant were removed in 2000 and samples were collected to confirm all sediments exceeding cleanup goals had been removed. Analytical results of samples collected more recently after operations had ceased indicate that sediments in the portions of the creeks on the Former Operating Plant still satisfy the 2000 cleanup goals.
Sampling of sediments in Stewart Creek at locations immediately downstream of the Former Operating Plant were performed as part of a separate Voluntary Cleanup Program project for the property located immediately downstream, and the City of Frisco has performed certain additional sediment and debris sampling farther downstream. Analytical results indicate there are several locations downstream where sediment contamination exceeds default TCEQ cleanup goals. Some small pieces of slag and plastic battery cases have been observed in Stewart Creek downstream of the Former Operating Plant. The City of Frisco has sampled this slag and battery chips, the results of which indicate some of the slag contains high concentrations of metals.
The APAR for the Former Operating Plant that has been submitted to the TCEQ and EPA cites both historical Stewart Creek data collected as part of previous Exide investigations as well as other investigations of downstream Stewart Creek sediments. The historical Exide sediment data are provided in Table A17-3A in Appendix 17 of the APAR. Table 1C of the APAR provides a summary of the respective investigation reports from which this data was obtained. Further discussion of the studies performed for Exide is provided in Section 7.3 of the APAR and in Section 2.1 of the Screening-Level Ecological Risk Assessment (SLERA) (the SLERA is included as Section 9 of the APAR).
Other off-site studies, including sediment sampling performed as part of the investigation of the downstream Former City of Frisco Stewart Creek Wastewater Treatment Plant, and Southwest Geosciences (SWG) March 2013 Sediment Sampling of Stewart Creek in downstream areas, are discussed in Section 7.3 of the APAR and Section 2.1 of the SLERA. These sections discuss sediment sampling results, including descriptions of locations where sediment with elevated concentrations of lead and cadmium were detected. These previous investigations identified areas of sediment containing elevated metals concentrations, and recommendations for further evaluation were also highlighted in the Conclusions and Recommendations Section of the Executive Summary of the APAR (p. xii). Section 7.3 of the APAR also refers to a second SWG study reported in May 2013 that included a walking survey to identify plastic battery case fragments and potential slag in the Stewart Creek downstream of the Former Operating Plant and notes that SWG will be performing additional investigation of sediments within downstream areas of Stewart Creek after preparation of the APAR. The data included in Attachment B of the City of Frisco’s Former Operating Plant APAR comments that were available when the APAR was submitted to the TCEQ and EPA were included in the aforementioned SWG March 2013 report that was discussed in Section 7.3 of the APAR and Section 2.1 of the SLERA. The final statement on page 7-2 of the APAR includes the recommendation that “potential stakeholders (City of Frisco, Exide and others) collaborate to discuss the investigation results and approaches for evaluation/response.”
As detailed in the October 29, 2013 responses to TCEQ and EPA comments on the Former Operating Plant APAR, Exide will include downstream portions of Stewart Creek in the revised APAR submittal and will perform further investigation as requested by the TCEQ. Also on November 7, 2013 Exide submitted to the TCEQ a document titled Interim Action Work Plan Slag and Battery Case Fragment Removal and Disposal to cleanup portions of Stewart Creek downstream of the Former Operating Plant. This document was prepared and submitted at the request of the TCEQ.
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