Formatted Title:

Development of Sediment Sampling Techniques in Enclosed Systems

Background/Objectives:

Washington, DC, has many tributaries that begin in closed stormwater sewer systems. These major tributaries include Watts Branch and Nash Run which are major tributaries to the tidal Anacostia River and have been identified as potential sources of industrial discharges and sewage to the river. A range of innovative sampling techniques are being used in a challenging, high-traffic environment to identify and track the sources of this contamination. Washington, DC, has been tracking illicit connections in many tributaries of the Anacostia. The Manhole-based sampling used in the past has provided limited information and passive sampling techniques are proving effective in achieving the investigation objectives. These sewersheds are characterized by dense urban industrial and residential development and continue with a mostly open stream. The main stem of these systems turns into an open stream and downstream, and the sewershed discharges to an open channel stream to its confluence with the Anacostia River. It is suspected that illicit connections to the piped stormwater system have contributed to the degraded sediment and water quality. With light commercial and residential properties located in these areas, illicit discharges are suspected as the main contributor to the contamination. The objective of this presentation is to describe how the historical use of traditional sampling methods drove the development of a passive sampling sediment trap. This passive sampling sediment trap was used in an integrated methodology for identifying and tracking potential sources of the illicit discharges and to highlight the success and lessons learned.

Approach/Activities:

This study will summarize the combination of field techniques used to perform this investigation and highlight the use and design on a novel passive sampling sediment trap. The strengths and obstacles in the implementation and development and how it was integrated into the investigation will be discussed along with the data analysis procedures and the preliminary results. The techniques used in the overall investigation include in-pipe closed circuit television (CCTV) surveying, water sampling for chemical analysis, sucralose and forensic fingerprinting, passive and discrete sampling, and physical dye testing of suspected facilities.

Results/Lessons Learned:

As more illicit source tracking projects are used to eliminate sources of contamination to the Anacostia River, the investigation process has become more streamline. The development of the passive sediment sampling trap has allowed our team to collect sufficient volumes of sediment to add sample locations that were previously unobtainable. The use of these samplers fills data gaps in traditional illicit source tracking programs. The effectiveness of the sampler can be used in conjunction with the traditional sampling techniques as opposed to a single method of source tracking. The lessons learned in using this newly developed passive sampling sediment trap as part of the investigation for Watts Branch and Nash Run are presented along with the general lessons learned that could be applied in other surface water source tracking efforts.

Antoine Muller

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(Group 1, Poster Board #16) Development of Sediment Sampling Techniques in Enclosed Systems