Featured Webinar: Alternatives to Traditional Onsite Wastewater Systems

This hour-long webinar recording from the Rural Community Assistance Partnership (RCAP) focuses on alternatives and advancements in traditional onsite wastewater systems and their unique applications and uses, including constructed wetlands, cluster systems, package systems, mound systems, etc. 

Alternative/ Innovative Onsite Wastewater Treatment Options:

Constructed Wetlands: A form of secondary or tertiary wastewater treatment that can be used by large municipalities and single-family homes alike. It is an organic wastewater treatment system that mimics and improves the processes that help to purify water in the same way as naturally occurring wetlands. This option uses water, aquatic plants, naturally occurring microorganisms, and a filter bed (containing sand, soil, and gravel.) 

There are two types of constructed wetlands: Surface Flow and Subsurface Flow wetlands. Surface Flow wetlands resemble natural wetlands in looks and the way they provide treatment. They are more economical for large volumes of wastewater. Subsurface flow wetlands are the most common type of constructed wetlands to treat household wastewater onsite.

Cluster Systems (also known as Community Systems): A decentralized wastewater treatment system under common ownership and collects wastewater from two or more dwellings or buildings. Cluster systems convey wastewater to a treatment and dispersal system located near the dwellings. These can be as simple as a subsurface disposal field served by individual septic tanks, or as complex as a neighborhood collection treatment and disposal system. 

Cluster systems transport wastewater via alternative sewers to either a conventional treatment plant or a pre-treatment facility followed by soil absorption of the effluent. The advantages of a cluster system are the shared costs with installation and future maintenance, but the disadvantages are undefined ownership and making sure everyone involved observes their responsibilities.

Pressure Manifold System: Uses pressure to distribute effluent in a more even, measured dose. Good for overcoming limitations of distribution boxes. Level manifold systems for effluent to flow equally via gravity. Sloped manifold systems have lateral trenches at various elevations to ensure that all branches operate at equal pressures.

Low Pressure Dose System (LPD): An anaerobic septic system with addition of a pump tank. Advantages with this option are that it can be installed in heavy clay soils, and it reduces the amount of land area required by the drainfield. Disadvantages include potential infiltration by roots, clogging of drain hose by solids, and wastewater accumulation in the drainfield. This system is not a viable option if water table is detected.

Drip Distribution system: Provides effluent dispersal that can be used in many types of drainfields. This alternative disperses treated septic water over a greater surface area of land. It irrigates the field with long flexible tubing that maximizes the treatment of sewage and minimizes the risk of untreated wastewater flowing too quickly through the soil. No large mound of soil is needed. This option requires a large dose tank to accommodate the time dose delivery of wastewater to the drip absorption area. A potential disadvantage of this method is that it needs electrical power which comes with increased maintenance and extra expenses.

Chamber System: This alternative contains no gravel in the drainfield. Instead, the drainfield is made up of synthetic chambers with bases that are open to the ground to allow effluent to drain into surrounding soil. Advantages with this method are increased ease of delivery and construction, they offer a large wastewater treatment volume, and it's good for areas with high water tables. Disadvantages are that this option will be expensive to install if the site has lots of gravel and sand, and this system could pollute the water table if the soil in the area has a high absorption rate.

Evapo-transpiration System (ET): Provides onsite wastewater treatment and disposal. Can dispose of wastewater into the atmosphere through evaporation from the soil's surface and or transpiration by plants. This option offers flexibility with the combination of seepage and evaporation, has a low risk of groundwater contamination, and it can overcome site, soil, and geological limitations that may come up. It is not suitable where land space is limited, or the surface is irregular. This alternative is only useful in arid climates with adequate heat and sunlight (it can fail if it rains or snows too much.)

Mound System: Good for areas with a shallow soil depth, high water table, or shallow bedrock. This method requires substantial amounts of space and periodic maintenance. Trees must be removed or cut back, and sand must be brought in to build the mound. This alternative can be expensive to install. 

Sand Filter: Provides a high level of treatment for nutrients and is good for sites with high water tables or are close to water bodies. With this option, treated water can pass directly from the sand filter to the soil without needing to pass through a leach field. 

Traditional approaches to onsite wastewater treatment are useful in many circumstances, but innovative alternatives are often the best choice for any unique situations that may arise. The alternatives to conventional septic systems mentioned above allow for cost-effective, long-term solutions if a traditional septic system is causing water quality problems.