Fulda, Indiana - A Cost-effective Solution for Small Unsewered Communities

THE PROBLEM: The unincorporated community of Fulda, Indiana is located in the northeast portion of Spencer County which has the Ohio River as its southern border. Founded in 1845 and centered round the parish of St. Boniface, Fulda had a problem shared by literally hundreds of small communities in Indiana. Due to past practices of sewage disposal, soil limitations and small lot sizes, most of the septic systems in the Town discharged to existing stormwater drains and a small creek. Due to sewage in exposed ditches and severe odor during warm weather months, the community knew the problem had to be addressed. Unfortunately, the only options offered by previous feasibility studies were the conventional solutions such as conventional gravity sewers discharging to mechanical treatment plants or transporting sewage by force mains to neighboring communities. Options which proved to be too expensive for the residents, both in terms of capital costs and, more importantly, operation, maintenance and replacement costs.

In an effort to find a viable solution to its problem the community formed a Regional Sewer District (RSD) and sought help from Bernardin, Lochmueller and Associates, Inc. and Natural Concepts Water Quality Engineering, LLC, a subsidiary of Bernardin, Lochmueller and Associates, Inc.

The goal of the RSD was to implement a community sewage collection and treatment system that would have a monthly user fee of approximately $60 per month. Previous investigations by concerned community members and county representatives had resulted in conventional systems that would cost anywhere from $80 to $120 per month depending on finance sources.

Based on preliminary planning, the sewered area consisted of 64 total connections; 59 residential connections, 1 church, 1 tavern, 1 gas station, 1 community center and 1 small industry. The average daily design flow was estimated to be 8,750 gallons per day.

THE SOLUTION: Natural Concepts Engineering, Inc., prior to becoming Natural Concepts Water Quality Engineering, LLC, had developed a natural treatment system that shows promise for meeting Indiana ground water standards for drinking water on a consistent year-round basis. The system, which has been named the Eco-Treatment SystemTM, consists of three primary components; a 9,700 square feet subsurface-flow constructed wetland, a vegetated recirculating gravel filter which lies atop the first 1/3 portion of the influent end of the subsurface-flow constructed wetland and a 3.6 acre soil absorption system using GEOFLOW, Inc.’s subsurface drip irrigation systems.

The Eco-Treatment SystemTM is proving to be cost effective, particularly in operation and maintenance costs, which are 1/4 to 1/3 of the costs for conventional treatment systems.

The key features of the Eco-Treatment SystemTM are:

  • Evapotranspiration – significant reduction of effluent discharged to the subsurface drip irrigation system during warm weather months.
  • Root systems that help to prevent plugging of media and detain the recycled water, which dramatically increases the detention/treatment time within the aerobic portion of the vertical wetland.
  • An anoxic zone with a continuous input of carbon to drive denitrifcation.
  • Requires only pumping for recirculation of the wastewater within the wetland.
  • Maximizes total nitrogen removal.
  • Green space utilization using GEOFLOW, Inc.’s subsurface drip irrigation systems.

PERFORMANCE:

The system for Fulda was permitted as a land application project which requires the application area to besized so that the pounds of Nitrogen applied on an annual basis does not exceed the theoretical uptake of the planted crop. However, the specific goal in the development of the Eco-Treatment SystemTM was to have a system that was mechanically simple and that could meet Indiana’s groundwater standard for total nitrogen concentration of 10 mg/l or less on a year round basis. The testing results from the first 12 months of operation for the Fulda system, while well within limits established by its land application permit, show the promise of obtaining the this goal, with effluent averaging less than 10 mg/l on an annual basis.