Purdue Residential Onsite Wastewater Disposal: Septic system information to protect your family and the environment 
 

Small Communities

Many older communities face significant challenges for sewage disposal. Approximately 700 unsewered communities in Indiana have small lots that are poorly suited for on-site systems. Cluster systems transport wastewater via alternative sewers to either a conventional treatment plant or to a pretreatment facility followed by soil absorption of the effluent. Cluster systems can be environmentally sound, finanacially responsible solutions for small community wastewater problems, where conventional central treatment systems are not practical or affordable and where individual on-site systems are inappropriate because of site or soil limitations. Small Community Wastewater Cluster Systems (ID-265) (soon to be available on the Web) answers questions about cluster systems and obtaining funding for community systems. 

EPA's Office of Wastewater Management has a Web site for small communities.
 

Types of Small Community Systems
Domestic wastewater must be properly managed to avoid public health problems. Three types of wastewater handling systems can be used in small communities.
Your community might need a combination of these systems, such as onsite systems in outlying areas, cluster systems in small residential subdivisions, and centralized systems in more populated or commercial areas.

 

Onsite Systems

Septic systems handle the wastewater from one residence on site. These systems are very common in small communities where homes are not close together. Septic systems consist of a tank that retains the wastewater solids and a drainage field (leachfield) where the tank effluent is distributed. In the leachfield, natural processes purify the liquid as it drains through the soil.

Conventional septic systems work best on large lots with deep, permeable soils. A variety of alternative onsite system designs are available to accommodate a range of difficult site and soil conditions. The most appropriate system depends on factors such as soil permeability, depth to water table, and depth to limiting layer.

Poorly sited, designed, installed, or maintained septic systems can result in surface ponding in yards. Surface ponding that continues for an extensive period is considered a health hazard and requires corrective action. Because maintenance is the only factor that can be controlled once an onsite system is installed, a program of periodic inspection and/or pumping is advisable. This approach, combined with public education to ensure that owners are putting only appropriate materials down the drain, is the easiest to implement. Repairs and replacements should always be done by professionals with the approval of local or state authorities, since exposure to inadequately treated sewage and hydrogen sulfide gas presents a health risk.

Although individuals usually own septic systems, a community can take a variety of steps to maintain effective systems, including: 

  • Periodically inspecting the system and requiring pumping when necessary.

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  • Requiring an operating permit that must be renewed periodically to ensure maintenance.

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  • Keeping files of all septic system locations and maintenance performed.

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  • Requiring prior approval by the town or county health officer of all repairs and replacements.

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  • Setting up a fund to help homeowners with needed repairs or replacements.

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In some states, legislation permits setting up onsite wastewater management districts. Of course, one important way to improve the performance of an onsite system is to conserve water. This reduces the volume of water the system has to handle. Detecting and repairing leaky faucets and toilets, using low-flow showerheads, toilet dams, low-flush toilets, and faucet aerators, and eliminating wasteful water use habits all conserve water.

 

Cluster Systems

In some neighborhoods individual onsite systems are inappropriate, either because lots are too small or because other land characteristics make them impractical. In this situation, a cluster system might be appropriate. A cluster system normally uses low-cost alternative sewers to collect wastewater from homes in the area and transport it to a reliable, low-cost, easily operated treatment/disposal facility. This type of system can be suitable for developments or neighborhoods of up to 100 homes but is often used for smaller groupings.

Several types of alternative sewer systems can be used to collect and transport wastewater from residences to the treatment facility. The treatment facility is usually a larger version of an individual onsite system, such as subsurface soil absorption systems or sand filters. 

As with any treatment system, a maintenance program is essential to ensure proper operation of a cluster system. Compared with conventional collection and treatment systems, cluster systems require minimal maintenance. The maintenance program, however, should always be in place and clearly spelled out to homeowners who use the cluster system.
 

 

Centralized Systems

In more densely settled areas, where multiple cluster systems are needed and onsite systems are not practical, a centralized wastewater system might be necessary. Constructing conventional sewers to collect the wastewater, however, is almost never practical for small communities because of the high cost. Conventional sewers usually account for over three-quarters of the total cost of a conventional wastewater collection and treatment system. The high cost of constructing the sewer system might be acceptable on a per-household basis, however, if no lift stations are required, but alternative designs are almost always cheaper under the same circumstances. Alternative sewers--small-diameter gravity, pressure, and vacuum sewers--can save 25 to 50 percent of the capital cost of wastewater collection in small communities.

Gravity sewer

Many types of technologies are available for treating wastewater at a centralized plant. Natural treatment technologies use natural processes associated with soils, vegetation, or wetland environments to treat wastewater and include land treatment, lagoons, slow sand filters, and constructed wetlands. These systems generally require larger land areas than mechanical systems. Wastewater must be treated (usually by sedimentation or lagoons) before application to land, filters, or wetlands.
 

Information above is an excerpt from the following publication:

Environmental Planning for Small Communities, A Guide for Local Decision-Makers, EPA/625/R-94/009, September 1994, United States Environmental Protection Agency, Office of Research and Development, Office of Science, Planning and Regulatory Evaluation, Center for Environmental Research Information, 26 West Martin Luther King Drive, Cincinnati, Ohio 45268, Office Of Regional Operations and State/Local Relations, Washington, DC 20460
 

 

Educational Tutorials

Other Resources

  • NDWC Water Sense Newsletter

    • Water Sense is a newsletter aimed at helping small communities learn about different ways to finance their drinking water (and wastewater) projects. The quarterly newsletter offers information about funding sources and funding criteria, financing resources, regulations, cost-saving strategies, and innovative financing mechanisms. Sign up to receive a free copy.