There are only two types of Household Sewage Treatment Systems (HSTS) used in Clermont County. At a basic level that is a correct statement, much like saying there are only two types of vehicles to drive, cars or trucks. But just like there are many variations of cars and trucks, the same is also true for HSTS. Sure you start out with only two basic types of HSTS for residential wastewater treatment, a soil absorption system or a discharging system, but once that distinction is made there are many options that homeowners can choose.
There are ten different brands of discharging systems approved through the Ohio Department of Health. All of these systems must be covered by Ohio EPA’s discharge permit prior to installation. Currently, only four of the brands are used in the county because they are the ones which have distributors in this area and have met the Quality Installation Assurance program requirements. All of the discharging systems use differing types of technology to introduce oxygen to the effluent, the term used to describe the liquid in a septic tank. Some use a simple air pump to blow air into a septic tank while others spray the effluent over a media such as peat or porous plastic fabric panels. The oxygen encourages aerobic bacteria to grow on the media and as the wastewater washes over the bacteria on the media they absorb the nutrients from it cleaning it up significantly. The effluent is then passed through a component to kill any bacteria that are floating in it. These components generally use either chlorine or UV light to kill the bacteria. All discharging systems must be covered by Ohio EPA’s very strict discharge permit, have a service provider and be sampled annually to be sure they are performing within the discharge permit’s requirements. There have been some rumors that the original trickle sand filter has been approved again for use by the Ohio Department of Health and that rumor is partially true. It has been approved for use, but only as a pretreatment device going to a separate soil absorption component such as leach lines or a mound. New construction of sand filters going directly to a swale or a creek ended with EPA limitations on discharging systems back in 2006.
When it comes to soil absorption systems there are at least 22 variations. That may seem hard to believe, but every company that manufactures a pretreatment device can use that device in conjunction with some form of soil absorption component. There are three variations of soil absorption components which are leaching trenches, drip irrigation or the much-maligned mound. Leaching trenches can be the perforated pipe and gravel units we are all used to in this county, but there are other products that essentially do the same thing. There are leaching chambers, perforated pipe surrounded with Styrofoam peanuts held in place by a plastic net and large diameter perforated pipe designed to be buried and covered only with soil. Again these are only variations on a theme.
Drip irrigation is a small diameter pipe (approximately one inch) that is pressurized with either pretreated or septic tank effluent. There are holes with emitters to control the flow at one-foot intervals along the pipe. Each emitter restricts the flow to a steady drip while the pipe is pressurized to only allow a very small amount of liquid into the soil giving it an excellent chance to be absorbed and cleaned as it moves away from the system.
The downside to both of these types of soil absorption systems is that they require a well-drained soil to operate effectively and there are not a lot of areas in Clermont County that have well-drained soils. Unfortunately, that makes the use of these soil absorption components limited. The mound structures are basically above ground sand filtration systems. Effluent is spread evenly across the top of a long narrow pile of sand and bacteria growing on the sand particles clean the effluent prior to it moving into the soil profile. How clean the effluent is before it is pumped to the mound determines how large the mound must be. Dirtier effluent has to go through more sand to get treated properly before it reaches the soil. Effluent that is pretreated by another component can be pumped over a thinner layer of sand, but effluent that comes straight from the septic tank has to go to a taller structure such as a Wisconsin or Millennium Mound.
There is a persistent rumor that the Clermont County Public Health only uses mound systems for household sewage treatment systems. Actually, Public Health accepts all designs that are based on the soil type and site topography for a given lot and that comply with existing regulations. Conventional wisdom forty years ago said that if the sewage went away that was good enough. Today we want to be sure the sewage is treated and clean before the water finds its way into the county’s aquifers, streams or rivers. We routinely hear from people in the county who tell us that their old leach bed/leach line system worked just fine, and it probably did. But what you have to consider is that many of those older systems were designed for homes that depended on private water systems for their supply of potable water. People living on a cistern or a well are typically very frugal with their water usage and that allowed a septic system that was installed in a poorly draining soil a chance to at least keep the sewage below the surface of the ground. To put this into perspective a 1930s Ford Model An automobile would go up and down today’s highways just fine, but don’t expect it to keep up with traffic on a daily basis. An old system design might work in a poor soil if it isn’t required to handle today’s water usage flows, but who wants to live under that type of water usage restriction?
When it comes to sewage treatment there is a lot of misinformation floating around Clermont County and even around the state of Ohio. One fact that is the absolute truth is that we have one of the best counties in the state to live in but we have some of the worst soils in the state for installing septic systems. The Health District is always working to find the best possible system for the soil conditions where the system will be operating and homeowners almost always have choices.
So when you hear someone telling you something like “there are only two types of household sewage treatment systems installed in Clermont County” or the old standard – “mounds don’t work”, please contact Clermont County Public Health at 732-7499 if you want to get the rest of the story. Someone will be happy to discuss the issues with you and get you all the facts.