Brad Ross: Another first for Delaware County

Brad Ross - Contributing columnist

Delaware County is high on the list in terms of “claims to fame.”

Ours is the number one county in the U.S. in growth for senior citizens, the third healthiest county in Ohio, we are home to the world-famous Columbus Zoo and Aquarium, and we host the internationally recognized Memorial Tournament at Muirfield Village Golf Club.

Delaware County is associated with national figures, such as Rutherford Hayes and Branch Rickey.

Now, we can lay claim to the first two-stage agricultural practice designed to improve water quality — the bioreactor and phosphorus removal structure system that was recently constructed in Porter Township. Once you come down from the rush of euphoria and excitement, please read on for more information!

This research project is part of a Regional Conservation Partnership Program grant from the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS) to promote conservation practices that improve water quality and soil health in the Upper Big Walnut Creek watershed.

Delaware, Knox, Licking and Morrow soil and water conservation districts are partnering on the grant since all four counties have acreage in the Upper Big Walnut Creek watershed. The creek drains to Hoover Reservoir in southeastern Delaware County and is an important drinking water source for the city of Columbus, another partner in the grant.

While bioreactors have been around for a few years, primarily in Corn Belt states west of us, they are a relatively new practice in Ohio and were added as an NRCS standard and specification in 2014. A few bioreactors have been installed in Ohio the past few years in the Western Lake Erie Basin; however, ours is unique in that it is paired with a phosphorus removal structure and the system will be monitored by USDA Agriculture Research Service scientists for five years, and maybe more.

The first part of our two-stage system is the bioreactor. Our particular bioreactor is a trench in the ground measuring 25 feet in width, 75 feet in length, and 24 inches in depth. This space is filled with wood chips and the secret is that the bacteria in the wood chips convert nitrates into nitrogen gas, effectively removing the nitrates from the crop field tile. The low flow of the field tile is routed into our bioreactor while higher flows continue to the outlet ditch. It is expected the bioreactor will last 10 to 15 years with little maintenance.

The second part of our system is the phosphorus removal structure. Such structures are not yet on the NRCS standards and specifications for Ohio but are approved in a few states. Our structure measures 37 feet by 48 feet and has a specially treated steel slag 18 inches in depth. The bioreactor outflow, as well as the bypass tile, is routed into the P removal structure, effectively treating all of the tile water from the crop field.

By now you are scratching your head and wondering what this whole thing looks like and why we are bothering with it. Once constructed, the bioreactor and phosphorus removal structure are covered with soil and seeded to grass and will be unnoticeable. In most cases, these structures will be installed in the edges of fields and not take land out of production.

The only above-ground signs of all this hard work will be the three water-quality monitoring stations. Nutrients in the form of nitrogen and phosphorus are found in tile and surface runoff from farm fields, home sewage treatment systems, storm sewer overflows, animal manure, golf courses, lawns and landscaping. An excess of these nutrients can lead to harmful algal blooms which are unfortunately in the news locally, nationally and worldwide. The partnership with USDA Agriculture Research Service will provide us with cutting-edge research on the efficiency and cost-effectiveness of these two systems, both as individual systems and as a two-stage process. A monitoring station will be established at three points – on the existing field tile before it enters the bioreactor, on the outflow of the bioreactor, and at the outflow of the phosphorus removal structure.

Nitrogen and phosphorus are essential to growing crops and providing food, fiber and fuel for all of us. Even under top management, these nutrients can percolate into our waterways and become hazardous to humans and animals, wreaking havoc with recreation, tourism and drinking water sources. Promoting conservation of our soil and water resources is part of the mission of the Delaware Soil & Water Conservation District – helping you help the land. Visit us at or

Brad Ross

Contributing columnist

Brad Ross is communications specialist at the Delaware Soil and Water Conservation District. He can be reached at [email protected]

Brad Ross is communications specialist at the Delaware Soil and Water Conservation District. He can be reached at [email protected]