From August/September to January:

4 flooding events

Approximately 1,650 yd3 of sediment stored in the basin

Average storage of 0.46 ft3

Pb concentrations range from

Spatial analysis of sedimentation and lead storage within an off-line floodplain basin system at the Big River Lead Remediation Structure Site, Bonne Terre, Missouri

Josh C. Voss (Voss123@live.missouristate.edu) and Robert T. Pavlowsky Department of Geospatial Sciences in Geography, Geology, and Planning, Missouri State University, Springfield, MO

Abstract

Preliminary ResultsBackground

Study Area Methods

Acknowledgements

Works Cited

I’d like to thank the US Environmental Protection Agency for funding this project, Bob Pavlowsky, Marc Owen, Ozarks Environmental and Water Resources Institute (OEWRI) for all their help and resources, and Deana Gibson for printing this poster.

Conclusions

This study involves the use of field and laboratory methods to assess the sedimentation and storage of contaminated sediment in the basin.

• 25 sampling blocks set throughout the basin

• Depth of sediment samples deposited on top of blocks measured after flooding events

• Sediment samples brought back for physical and geochemical analysis

• Real-time kinematic (RTK) GPS points collected throughout basin multiple times to measure changes and total storage

• Sediments samples were dried, weighed, disaggregated, and sieved through 16mm, 8mm, 4mm, and 2mm sieves

• Sediments <2mm were analyzed using an X-MET3000TX+ Handheld X-ray fluorescence (XRF) Analyzer (OEWRI, 2007)

• Field and laboratory data mapped and analyzed in ArcMap

Pavlowsky, R.T., Owen, M.R., and Martin, D.J., 2010, Contaminatedsediment geochemistry, distribution and storage in channeldeposits of the Big River in St. Francois, Washington, and Jefferson counties, Missouri – Final Report.

OEWRI, 2007, Standard Operating Procedure for X-MET3000TX+Handheld XRF Analyzer. Ozarks Environmental and WaterResources Institute, Missouri State University.

Owen, M.R., Pavlowsky, R.T., and Martin, D.J., 2012, Big Riverborrow pit monitoring project-Final Report.

Smith, B.J., and Schumacher, J.G., 1993, Surface-water andsediment quality in the Old Lead Belt, southeastern Missouri-1988-89: U.S. Geological Survey Water-Resources Investigations Report 93-4012.

Old Lead Belt Southeastern, MO (Smith and Schumacher, 1993)

From June 2015 to January 2016:

• 8 flooding events occurred

• Location and area of sedimentation basin = 12,530 yd2

• Volume of sediment deposited since Sept. = 1,650 yd3

• Sediment depth RTK survey = 0.46 ft3 average (-1.23 – 4.763 ft3)

• Sediment depth sample block = 0.42 ft (0.026 – 1.97 ft)

• Pb concentrations in deposited material (91 samples) = 1175

ppm average (516 – 2315 ppm)

There are four main conclusions thus far:

1. Since September 2015, the basin has trapped

1,650 yd3 in an area about 12,530 yd3

2. Overbank flood inundation time seems to

correlate with deposit depth averaging 0.46

ft3, ranging from -1.23 – 4.763 ft3

3. Pb concentrations in trapped sediment

average 1175 ppm, ranging from 515 – 2315

ppm

4. Monitoring will continue and lower basin

deposition trends will also be evaluated

Locations of tailing piles and study area (Smith and Schumacher, 1993)

Location of constructed basinReal-time kinematic (RTK) GPS

Scale, sieves, and mortar and pestle

X-MET3000TX+ Handheld X-ray fluorescence (XRF) Analyzer

Sampling block and post

Sediment accumulated in the basin from Sept. to Jan.

Sediment deposited on top of sampling blocks

Average Pb concentrations (ppm) of sediment collected from sampling blocks

Constructed basin and chute

Gage height (blue) upstream of basin from June to January with bankfull height (red)

Sediment deposited from Dec. flood on NE portion of the basin (top) and block (bottom)

Most of the mining areas located in the Old Lead Belt are drained by the Big River. The Big River is a perennial, gaining stream with the Flat River being its largest tributary (Smith and Schumacher, 1993). The Big River flows roughly east to north where it drains about 2,500 km2 before is converges with the Meramec River.

The constructed basin system was built along the Big River near Bonne Terre, Missouri. The basin structure was completed in April 2015 and designed by the US Army Corps of Engineers to trap contaminated sediment and reduce downstream Pb loads. The basin was built along the inside of a large valley bend near the confluence with the Flat River and mimics the hydrologic and sedimentation functions of a natural chute-backswamp system.

Lead (Pb) was mined for more than 100 years in southeastern Missouri in an

area known as the Old Lead Belt. The Old Lead Belt was the leading producer of

Pb from 1869 to 1972 (Smith and Schumacher, 1993; Pavlowsky et al., 2010).

These mining operations created large volumes of metalliferous waste that were

stored in piles and slurry ponds (Pavlowsky et al., 2010). These mining

operations were responsible for the large-scale release of mineral wastes and

lead (Pb) to the Big River (Smith and Schumacher, 1993). It was not until after

WWII that mining waste was confined to impoundments. Before this, waste was

released freely to the surrounding landscapes and streams. Even after mine

closure, waste still entered streams by erosion, slope failures, and dam

breaches. As a result, over 170km of floodplain and channel deposits were

contaminated by Pb and other heavy metals. While it is evident that this

sediment is contaminated, less is known about the patterns and rates of

sedimentation in floodplain areas (Pavlowsky et al., 2010). Even less is known

about how to use floodplain structures to trap contaminated sediment for

remediation purposes. That information is needed to evaluate the long-term

effects of contaminated sediment and to assess the effectiveness of remediation

strategies (Owen et al., 2012)

Mining operations in the Old Lead Belt of southeast Missouri were responsible for the large-scale release of mineral wastes and lead (Pb) to the Big River resulting in the contamination of over 170 km of channel and floodplain deposits. While it is evident that sediment is contaminated, less is known about the patterns and rates of sedimentation in floodplain areas. Further, little is known about how to use floodplain structures to trap contaminated sediment for remediation purposes. The purpose of this study is to monitor the effectiveness of a constructed basin system along the Big River near Bonne Terre, Missouri. The basin structure was completed in April 2015 and designed by the US Army Corps of Engineers to trap contaminated sediment and reduce downstream Pb loads. It was built along the inside of a large valley bend and mimics the hydrologic and sedimentation functions of a natural chute-backswamp system. The objectives of this monitoring study include: (1) map out the as-built form of the basin system using GPS/GIS technology; (2) deploy and monitor between floods a sediment sampler array within the upper chute area where sediment from the river enters the structure; (3) assess the spatial patterns of sediment deposition and quality throughout the entire basin system; and (4) evaluate the basin for effectiveness for remediation purposes including recommendations for sediment removal scheduling and potential improvements to similar basin designs. This is one of the first constructed floodplain basins to be created for the purpose of managing long-term sediment contamination for rivers affected by mining contamination. After several flooding events, preliminary results show sediment was deposited throughout the basin structure, with significant amounts of sediment deposited near the upper channel chute. A majority of sediment samples collected to date contain Pb concentrations greater than 1,000 ppm. The final results of this study will improve our understanding of how sediment transport and deposition in rivers is influenced by variable flood characteristics and how channels recover from bank disturbances.

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0.15

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8/4/2015 9/17/2015 12/14/2015 1/21/2016

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Sampling Dates

Average Sediment Depths on Blocks

4 floods5 days overbank

1 flood 1 day overbank

1 flood 0.75 days overbank

2 floods5.5 days overbank

Average sediment deposited on top of blocks from each sampling date with number of floods and days over bankfull between dates

Sediment deposited from Nov. flood on the south (left) and north (right) side of road

Sampling block locations