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Scientific Investigations Report 2010–5076

In cooperation with the Lockheed Martin Corporation

Polychlorinated Biphenyls in Suspended-Sediment Samples from Outfalls to Meandering Road Creek at Air Force Plant 4, Fort Worth, Texas, 2003–08

By Christopher L. Braun and Jennifer T. Wilson

Abstract

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Meandering Road Creek is an intermittent stream and tributary to Lake Worth, a reservoir on the West Fork Trinity River on the western edge of Fort Worth, Texas. U.S. Air Force Plant 4 (AFP4) is on the eastern shore of Woods Inlet, an arm of Lake Worth. Meandering Road Creek gains inflow from several stormwater outfalls as it flows across AFP4. Several studies have characterized polychlorinated biphenyls (PCBs) in the water and sediments of Lake Worth and Meandering Road Creek; sources of PCBs are believed to originate primarily from AFP4. Two previous U.S. Geological Survey (USGS) reports documented elevated PCB concentrations in surficial sediment samples from Woods Inlet relative to concentrations in surficial sediment samples from other parts of Lake Worth. The second of these two previous reports also identified some of the sources of PCBs to Lake Worth. These reports were followed by a third USGS report that documented the extent of PCB contamination in Meandering Road Creek and Woods Inlet and identified runoff from outfalls 4 and 5 at AFP4 as prominent sources of these PCBs.

This report describes the results of a fourth study by the USGS, in cooperation with the Lockheed Martin Corporation, to investigate PCBs in suspended-sediment samples in storm runoff from outfalls 4 and 5 at AFP4 following the implementation of engineering controls designed to potentially alleviate PCB contamination in the drainage areas of these outfalls. Suspended-sediment samples collected from outfalls 4 and 5 during storms on March 2 and November 10, 2008, were analyzed for selected PCBs. Sums of concentrations of 18 reported PCB congeners (∑PCBc) in suspended-sediment samples collected before and after implementation of engineering controls are compared. At both outfalls, the ∑PCBc before engineering controls was higher than the ∑PCBc after engineering controls. The ∑PCBc in suspended-sediment samples collected at AFP4 before and after implementation of engineering controls also is compared to the threshold effect concentration (TEC), the concentration below which adverse effects to benthic biota rarely occur. ∑PCBc exceeded the TEC for 75 percent of the samples collected at outfall 4 and 67 percent of the samples collected at outfall 5 before the implementation of engineering controls. ∑PCBc did not exceed the TEC in samples collected at either outfall 4 or outfall 5 after the implementation of engineering controls.

The relative prominence of 10 selected PCB congeners was evaluated by graphical analysis of ratios of individual concentrations of the 10 PCB congeners to the sum of these PCB congeners. An overall decrease in concentrations of PCB congeners at outfalls 4 and 5 after implementation of engineering controls, as well as a shift in prominence from lighter, less chlorinated congeners to a heavier, more chlorinated congener might have resulted from the implementation of engineering controls. Because of the small number of samples collected and lack of runoff and precipitation data to evaluate comparability of sampling conditions before and after implementation of engineering controls, all conclusions are preliminary.

Revised March 15, 2011

First posted May 13, 2010

For additional information contact:

Director, Texas Water Science Center
U.S. Geological Survey
1505 Ferguson Lane
Austin, TX 78754-4501

http://tx.usgs.gov/

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Suggested citation:

Braun, C.L., and Wilson, J.T., 2010, Polychlorinated biphenyls in suspended-sediment samples from outfalls to Meandering Road Creek at Air Force Plant 4, Fort Worth, Texas, 2003–08: U.S. Geological Survey Scientific Investigations Report 2010–5076, 20 p.



Contents

Abstract

Introduction

Approach

Polychlorinated Biphenyls in Suspended-Sediment Samples from Outfalls to Meandering Road Creek

Summary

References Cited

Appendix 1. Concentrations of selected polychlorinated biphenyl congeners in suspended-sediment samples collected from outfalls 4 and 5, Air Force Plant 4, Fort Worth, Texas, 2003–07

Appendix 2. Concentrations of antibacterial, antifungal, pesticide, and flame retardant compounds in suspended-sediment samples collected from outfalls 4 and 5, Air Force Plant 4, Fort Worth, Texas, 2008


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