Where Does Wastewater Go?

In Harlan County all public wastewater systems are separate sewer systems; that is, storm water and sewage are collected in separate lines. 

You can tell a separate storm sewer system when it is made up of structures like retention basins, ditches, roadside inlets and underground pipes. These systems are designed to gather storm water and directly discharge it into local streams and rivers without being treated. It's called a “separate system” because it is not connected to the sanitary sewer system, which drains waste water from inside a home to a sewage treatment facility or a private septic system.

A combined sewage system, on the other hand, collects rainwater runoff from surfaces like asphalt, concrete, and roofs. That is -- from surfaces that do not absorb water -- and combines running sewage and industrial wastewater into the same pipe to transport all that wastewater to the treatment plant. You can tell that you are connected to a combined sewage system from the central sewage pipe.  This central pipe collects both storm water and wastewater coming from households, businesses and other human activities. 

Both separate or  combined  sewage systems are threatened by extreme weather events. For example, in case of flooding, the amount of storm water can surpass the system's capacity. This creates overflows, releasing untreated storm water and wastewater into nearby water bodies.  The likelihood of water containing sewage bypassing the treatment system after a heavy rainfall, as well as the huge variation in flows, make combined systems much harder to manage in comparison to separate systems. But even separate systems can suffer overflows and bypasses when the system is old and deteriorated; leaky pipes allow for infiltration of storm water and inflow from basement sump pumps improperly connected into the sanitary sewer system.

Did you know that overflows are called 'sanitary sewer overflows’ or ‘combined sewer overflows' (SSOs and CSOs) and are regulated) by the National Pollutant Discharge Elimination System (NPDES) permitting program?

Sources

US EPA, “Combined Sewer Overflows (CSOs)”. 

Kentucky Infrastructure Authority, WRIS Management Plans…..

Penn State Extension, June 2023, “What is an MS4?”. Stormwater Basics Education Series. 

Wastewater is used water. It includes substances such as human waste, chemicals, food scraps, oils, soaps and used water from residents, businesses, and industries. Wastewater also includes storm runoff that can pollute rivers and lakes, as harmful substances are washed off roads, parking lots and rooftops. Therefore, although we'd like to think that the rain that pours down the stream during a storm is clean or pure, there is a good chance that it is not! The main goal of treating wastewater is to reduce suspended solids and harmful chemicals to a level nature can handle, and disinfect the water before it is released back into rivers or streams. 

Suspended solids are fine particles of sediment in water and are made of organic and inorganic materials like sand, clay, silt, algae, bacteria and other contaminants. When the living organisms decay, especially the algae and bacteria, the process uses up oxygen that is in the water. Yet oxygen is necessary for the survival of the plants and animals living in an aquatic ecosystem; in other words, the life that exists in our source water. This lack of available oxygen can lead to the growth of harmful bacteria and to a wide range of waterborne diseases.

Water treatment is a matter of caring for the environment, including fisheries and wildlife habitats, as well as for our own health and quality of life and that of our children and childrens' children. A well functioning wastewater system helps prevent the spread of diseases, protects ecosystems, and ensures the sustainability of water supply for communities. That is why wastewater systems are critical and vital for public and environmental health, as well as for the well-being of communities and local economies.

Source

• US Geological Survey, "Wastewater Treatment Water Use". In Water Science School.

There are several types or levels of wastewater treatment; the primary (1st), secondary (2nd), and tertiary (3rd) levels of treatment. Most municipal wastewater facilities use primary and secondary treatment. The type and order of wastewater treatment may vary from one sewage plant to another. 

Primary treatment uses screens and settling tanks to remove items like wood, rocks, or even dead animals, which are sent to the landfill. This step is extremely important, because solids make up approximately 35 percent of the pollutants often found in water. After the screening phase, wastewater is pumped up to the aeration tanks (pumping). From there, gravity takes over to move the wastewater through the treatment process; water is put into settling tanks (or clarifiers), where it sits for several hours, allowing the sludge, which is the organic portion of sewage, to settle. It also allows scum --lighter materials like grease, oil, plastics and soap -- to float on the surface. The scum is then skimmed off the top, the sludge is removed from the bottom, and the partially treated wastewater moves on to the secondary treatment level. The primary treatment generally removes a significant amount of harmful substances from wastewater; up to 50%of substances that use up the oxygen in the water (the Biological Oxygen Demand), around 90% of suspended solids, and up to 55% of fecal coliforms. Yet, the primary treatment process is not enough to ensure that all harmful pollutants have been removed.

Did you know that the sludge and scum extracted through the primary steps are treated separately from the water? Anaerobic bacteria (bacteria that do not require oxygen) feed off of the sludge for 10 to 20 days at temperatures around 100 degrees Fahrenheit. This process decreases the odor and organic matter of the sludge, and creates a highly combustible gas of methane and carbon dioxide, which can be used as fuel to heat the treatment plant. 

The secondary treatment of wastewater uses “aerating” to replenish the oxygen and bacteria to digest the remaining pollutants. As organic matter decays, it uses up oxygen. To replenish oxygen, the wastewater treatment facility shakes up the sewage and exposes it to air. This causes some of the dissolved gasses (such as hydrogen sulfide, which smells like rotten eggs) to be released from water. The oxygen helps the bacteria digest the pollutants faster. The water then enters a series of long, parallel concrete tanks, where the sludge again settles, leaving the water 90 to 95 percent free of pollutants. Each tank is divided into two sections. In the first section, air is pumped through the water, keeping organic material suspended, while forcing small dense particles, such as coffee grounds and sand (“the grit”) to settle down. Grit is then pumped out of the tanks and taken to landfills. In the second section of these tanks, additional sludge removal takes place. Alternatively, the sludge is sent to a centrifuge, a machine that spins very quickly, forcing the liquid to separate from the solid. The liquid can then be processed with the wastewater.

Many cities also use filtration in treating sewage; after the solids are removed, the liquid sewage is filtered through a substance -usually sand- using the force of gravity. This method removes almost all bacteria and odors, and most of the solid particles that remain in the water after the sludge and scum removal. It also reduces turbidity and color, as well as iron.

The final step in the secondary treatment involves the use of chlorine; wastewater flows into ‘chlorine contact’ tanks, where chlorine is added to kill bacteria that could threaten human health. Sometimes, chlorine has to be neutralized by adding other chemicals, before discharging the treated water (called ‘effluent’) to a source water. 

Did you know that the solid waste materials that have been removed from primary and secondary treatment are kept for 20 to 30 days in large, heated and enclosed tanks (the ‘digesters’)? Here, bacteria break down (i.e. digest) the material, reducing its volume, odors and getting rid of organisms, pathogens and other contaminants that could cause diseases. What remains from this step - if not contaminated over certain levels- is mainly sent to landfills, but sometimes can also be used as fertilizer.

Tertiary (or advanced) treatment removes dissolved substances, such as color, metals, organic chemicals and nutrients like phosphorus and nitrogen. There are a number of physical, chemical and biological treatment processes that are used for tertiary treatment. However, no wastewater facility in Harlan County has treated wastewater at this level until now.

Sources

• United States ​​Environmental Protection Agency, Municipal Wastewater.

• Safe Drinking Water Foundation, Water Treatment. 

If you do not have access to a wastewater/sewage system, then you may have a septic system. Septic systems are usually found in suburban and rural locations not served by a public (centralized) sewer system. More than one in five households in the U.S. depend on individual (decentralized) septic systems, or small community cluster systems to treat relatively small volumes of wastewater. Decentralized systems are a cost-effective and long-term option for treating wastewater, especially in less densely populated areas.

A conventional decentralized wastewater treatment system consists of a septic tank and a trench or bed subsurface wastewater infiltration system, known as a drainfield. A conventional septic system is typically installed at a single-family home or small business.

To find your septic system, check your local land records. Usually your septic tank, drainfield, and reserve drainfield are clearly designated on the ‘as-built’ drawing for your home. You might also see lids or manhole covers for your septic tank. Older tanks are often hard to find because there are no visible parts. An inspector/pumper can help you locate your septic system if your septic tank has no risers.

Did you know in order to install a septic system in your yard, the soil must pass a "perc test," or "perk test?" This stands for percolation test, in which several holes are dug and filled with water to ensure the water can travel through the soil to disperse from a septic tank. If the soil is too compacted -- such as after surface mine reclamation, a high water table, or if rock layers don't permit water to be absorbed -- a septic system cannot be installed. In areas without public wastewater systems, a failed perc test can mean a building permit won't be issued.

Sources 

• US EPA,  “About Septic System” and “Types of Septic Systems”. In Septic Systems.

• US EPA, “Your Septic System is your responsibility”. In A Homeowner’s Guide to Septic Systems.

Any type of wastewater drainage system different from the standard septic tank is considered to be an alternative septic system. There are various ways--other than a conventional septic system--to divert and clean wastewater coming out of a home, and to safely reintroduce it back into the environment! Each of the alternative septic systems has a different level of cost, equipment used, and required maintenance. Examples of such alternative septic systems include:

• Drip Distribution System

• Aerobic Treatment Unit

• Mound Systems

• Recirculating Sand Filter System

• Evapotranspiration System

• Constructed Wetland System

• Cluster / Community System

To read more about these alternate systems, see the EPA's page on septic systems. 

Some of the conditions that can make households turn to alternative septic systems are difficult soils (such as clay soils, or too sandy); soils that “won’t perk” (won’t absorb and retain water); plots of land that are rocky or with bedrock, with not enough topsoil to treat and dispose of wastewater; in wet plots of land, or land near water bodies, with a lot of groundwater running underneath, or land subject to surface runoff, or even water pollution; in steep plots of land, where the installation of a conventional drainfield or sand bed is not permitted. Alternative septic systems are also often considered for small plots of land, when there is no adequate space to install a conventional septic system. 

TIP: If you build a conventional septic system in land that cannot absorb water, you will most certainly run into terrible flooding issues. That is why--before you decide to install a conventional septic system--you will have to pass the “perk test” (or perc test, which is short for percolation). This test helps you determine if the soil is fit to host a conventional septic tank. If your perc test doesn’t go well (or if there are other concerns) you can consider alternative septic systems. But, when considering an alternative system, keep in mind that a service contract is important, as alternative systems often have mechanized parts.

Sources

• US EPA, Your septic system is your responsibility. In A Homeowner’s Guide to Septic Systems.

• US EPA, “How to Care for Your Septic System”. In Care and Maintenance, Septic Systems. 

• US EPA, “Types of Septic Systems”. In Septic Systems.