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Water: Nonpoint Source Success Stories

South Carolina: Constructed Wetlands for Failing Septic Tanks: New Technologies Solve an Old Problem

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Contact:
Keith Cain
East Piedmont RCD Council
414A South Congress Street
Winnsboro, SC 29180
803-635-2757
Keith.Cain@sc.usda.gov
Primary Sources of Pollution:

failing septic tanks
Primary NPS Pollutants:

fecal coliform bacteria

nutrients
Project Activities:

constructed wetland systems
Results:

reductions of 99 percent in fecal coliform bacteria, 86 percent in total suspended solids, 77 percent in BOD5, 39 percent in total phosphorus, 59 percent in nitrate, 35 percent in ammonia

Failing septic systems can result in partially treated or untreated surface wastewater containing fecal coliform bacteria and nutrients, causing nonpoint source pollution in drainageways, streams, and lakes. Current technology resulting from a 3-year study on nine constructed wetland systems conducted by Dr. Kevin White of the University of South Alabama is being used in the design of constructed wetlands in South Carolina to treat sewage from failing septic systems.

The system consists of two shallow basins about 1 foot in depth and containing gravel, which supports emergent vegetation. The first of the two cells is lined to prevent seepage, while the second is unlined and acts as a disposal field. The water level is maintained below the gravel surface, thus preventing odors, public exposure, and vector problems. In an alternative design, a standard field drain system is used in place of the second cell.

Encouraging results

Preliminary data collected by the South Carolina Department of Health and Environmental Control (SCDHEC) between May 1999 and April 2000 on eight of these systems constructed statewide show significant reductions in nutrients and bacteria as a result of treatment. The monitoring shows an average 99 percent reduction in fecal coliform bacteria, 86 percent in total suspended solids, 77 percent in 5-day biological oxygen demand (BOD5), 39 percent in total phosphorus, 59 percent in nitrate, and 35 percent in ammonia.

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Sampling is conducted through sampling ports.

Education component

The East Piedmont Resource Conservation and Development Council is managing the construction of 10 of these wetland systems to replace failing septic tank systems at homes in a watershed surrounding Lake Murray. This lake is a large recreational impoundment in central South Carolina, where poor soil conditions and steep slopes are causing some conventional systems to fail. A comprehensive technology transfer program will complement the project, educating citizens about the benefits of the management practice. The Ninety-Six District Resource Conservation and Development Council is also conducting a similar project in Greenwood County.


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Stevens Creek Watershed Project:
Demonstration Sites Show Reductions in Fecal Coliform Bacteria

  



Contact:
Doug Fabel
South Carolina Department of Health & Environmental Control
2600 Bull Street
Columbia, SC 29201-1708
803-898-4222
fabeldj@ columb32.dhec. state.sc.us
Primary Sources of Pollution:

agriculture
Primary NPS Pollutants:

fecal coliform bacteria

sediment

nutrients
Project Activities:

dairy farm BMPs (grazing management, fencing, alternative water sources for livestock, riparian vegetation establishment)

nutrient management for poultry farm (dead bird composting)
Results:

reductions in fecal coliform bacteria

The Stevens Creek watershed is in Edgefield, McCormick, Greenwood, and Saluda Counties, South Carolina. Historical water quality data indicate increasing trends in fecal coliform bacteria, turbidity, and total phosphorus and decreasing trends in dissolved oxygen. Nonpoint source pollution is degrading the quality of water for municipal water supply, contributing to deterioration of fisheries, reducing stream channel capacities, and lowering the aesthetic values of the area. About 85 to 90 percent of the water quality impacts in the Stevens Creek watershed are estimated to be caused by agriculture.

Implementing best management practices

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Project partners built a two-cell composter on the Johnson Poultry Farm to reduce nutrients from poultry waste runoff.

The goal of the Stevens Creek Watershed Project was to reduce sediment, nutrients, and chemical runoff from confined and unconfined livestock operations. The Edgefield Soil and Water Conservation District and Ninety-Six District Resource Conservation and Development Council, Inc., implemented the project over a 3-year period between May 1995 and July 1998. The project focused on using systems of best management practices (BMPs) and whole farm planning and management as keys to the sustainability of farming operations. Section 319 funds and the farmers on whose farms the demonstrations were located covered the costs of the demonstrations.

Two farms in the watershed were selected as demonstration sites—a dairy operation and a poultry farm, both in close proximity to flowing streams. BMPs implemented on the dairy farm included pasture grazing management, stream protection by fencing off streambanks and providing alternative water sources for livestock, and additional riparian vegetation (field borders and filter strips). Nutrient management, in the form of dead bird composting, was the target BMP for the chicken farm. A waste stacking shed was built into the ground behind the poultry houses, with minimal soil disturbance. Both farms had BMPs implemented in June 1996.

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Testing revealed significant reductions in fecal coliform at Sleepy Creek downstream from Hickory Hill Dairy.

Taking stock of improvements

Three monitoring stations were established for each farm, one upstream of the project sites, one downstream, and a control (reference) site. Baseline data were collected from January 1996 through June 1996, and regular monitoring began in July 1996 and continued for 2½ years (through January 1999).

Water quality sampling results indicated significant reductions in fecal coliform bacteria at both the downstream poultry and dairy farm stations after BMP implementation. Preimplementation sampling found fecal coliform bacteria levels for all stations ranging from a low of 5 colonies per 100 mL to a high of more than 2 million colonies per 100 mL; postimplementation results for all stations ranged from 2/100 mL to 58,000/100 mL. Nutrient management (dead bird composting) on the poultry farm significantly reduced fecal coliform bacteria and total suspended solids concentrations (both spatially and temporally). On the dairy farm, pasture grazing management and animal fencing did significantly reduce fecal coliform bacteria concentrations (spatially and temporally), but they did not reduce total suspended solids concentrations at the downstream station.

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