The Blanchard River appears to be running full more days than not for the past year. Except for southern Hancock County, soils in the area have not completely dried out since about the fall of 2018. Subsoil and surface soil moisture levels have been adequate, or more often excessive, during this time.
The geologic nature of our soils is the cause of the slow drying process. Even though most of Hancock County is not in the geologic area called the Black Swamp, its soils are similar, having poor subsurface drainage caused by large deposits of fine to medium-textured particles — also known as clay.
Soils in the area were known to be fertile, but excessive water and drainage issues prevented practical use of the land. This changed in the late 1800s when technology allowed a complex drainage system to be built in the region, allowing for timely crops to be planted along with the establishment of cities and factories.
However, as villages and cities expanded and more people moved into the area, wastewater became more of an issue. The type and nature of indigenous soils greatly affects the ability of anyone living outside a municipal treatment facility (sewer system) to filter and treat wastewater in ways that protect existing ground and surface water.
The layers of the proper type of soil can remove suspended solids, organic material, ammonia, bacteria and viruses in wastewater. However, the pores of these soils must be fine enough to trap the suspended solids and disease-causing organisms in the wastewater.
The soil must also have sufficient pore space to allow adequate populations of aerobic microorganisms that will feed and degrade organic material and ammonia. Besides the right pore space, these soils must be deep enough to have the capacity to absorb viruses and potential water pollutants such as phosphorus.
Four feet or more of unsaturated soil above a limiting physical feature is necessary to protect the environment and public health. Types of limiting features found in Ohio include seasonable high water tables, hard bedrock, dense clays, glacial till zones, and zones of gravel and sand.
In our area, only about one percent of the soils have depths greater than 3 feet before hitting a limiting condition for wastewater treatment. The majority of our soils have a depth of 12 to 18 inches before a limiting condition.
Seasonable high water table (springtime) accounts for most of the limiting features and, for some soils, a dense till sublayer. To deal with a high seasonable water table, farmers use surface and subsurface drainage systems, cities have built surface systems for faster runoff, and homeowners have sump pumps in basements and crawl spaces.
Historically, wastewater systems for rural homes relied on a buried leach field. These systems are fine when the soil depth is 3 to 4 feet before a limiting barrier. If shallower, the leach field may prevent sewage from reaching the surface of the yard or backing up into the house, but it will fail to remove pollutants from the wastewater.
In our area, most of the soils are not deep enough for a leach field to adequately protect the environment and groundwater. In fact, depending on the county in our area, 39 percent to 80 percent of the soils are less than 1 foot in depth before hitting a limiting feature.
Engineers have developed alternative systems to leach fields for wastewater treatment in shallow soils. These systems are more complicated, require more maintenance and are more expensive than the traditional leach field.
It is known that many of our older homes, housing developments and villages in the rural area do not have adequate septic or sewer systems to protect the environment from potential water quality problems such as capturing phosphorus.
The state has recognized these problems and has offered funding to assist in the cost of replacing old and outdated septic systems. The Ohio Environmental Protection Agency also is working with rural villages to address wastewater issues. On the farm front, the governor created H2Ohio to provide agricultural funds to reduce phosphorus losses from farm fields.
Our soils and a source of water have been the foundation of most of the industries in our area. However, agriculture and communities will have to work together to properly manage these resources and protect them for future generations. Of course, Mother Nature could assist by having fewer intense rain events in the spring.
The Ohio State University Extension has an extensive library of fact sheets and bulletins that discuss Ohio soils and methods to treat wastewater, which is located at:
Specific information on soils and establishing a septic system may be found at https://ohioline.osu.edu/factsheet/aex-742
Lentz is extension educator for agriculture and natural resources for the Ohio State University Extension Service in Hancock County.