This image shows a typical home septic system
Typical home septic system

Septic systems, also known as onsite/decentralized wastewater treatment systems and subsurface sewage treatment systems (SSTS), treat sewage from homes and businesses that are not connected to a centralized wastewater treatment plant. Septic systems can vary in size and the number of dwellings served and include individual and cluster SSTS. Septic systems can be of conventional design (heavily relying on the soil for treatment along with dispersal) or use pre-soil treatment technologies like constructed wetlands, media filters, or aerobic treatment tanks followed by dispersal (with limited final treatment) in the soil. Soil treatment and dispersal options include in-ground trenches or beds or above ground at-grade or mound systems. The type of soil dispersal system is chosen based on the treatment abilities of the native soil in combination with the effectiveness of any pre-soil treatment that may be employed. SSTS can be protective of public health and water quality if properly planned, sited, designed, constructed, installed, operated, and maintained.

This fact sheet summarizes a step-by-step approach to developing a community management program for SSTS. It also provides an overview of the five management models outlined in EPA’s Voluntary National Guidelines for Management of Onsite and Clustered (Decentralized) Wastewater Treatment Systems. While this factsheet, based on EPA guidance, provides direction to MS4’s, Minnesota Statutes 115.55 and 115.56, which regulate SSTS, must also be consulted in the development of a comprehensive management program.

For more information, see MPCA's website for Subsurface sewage treatment systems.

Benefits and pollution reduction

Although some management programs are effective, many existing rules that regulate septic systems are not adequate to ensure proper operation and maintenance. Failure of septic systems is a term subject to much debate. Based on local units of government estimates, approximately 10 percent of all systems back up into homes or have wastewater emerging on the ground surface, and approximately 25 percent of the systems in Minnesota fail to protect groundwater.

Systems may not receive proper maintenance because owners are either unaware of the need for maintenance, or believe it to be unnecessary or too costly. Improper operation and maintenance will result in premature clogging of the soil’s infiltrative surface which may result in system back-up or seepage on the ground surface. Generally improper maintenance does not result in groundwater contamination; improper operation of SSTS (such as the discharge of hazardous waste or other non-treatable wastes into the system) will result in groundwater contamination. The MPCA’s Detailed Assessment of Phosphorus Sources to Minnesota Watersheds has identified a method to quantify the phosphorus discharging from nonconforming or failing septic systems (MPCA, 2004) and could be used by an MS4 to estimate the phosphorus loads coming from local systems.

The study states that throughout Minnesota, failing septic systems have relatively direct connections to surface waters resulting in the increased potential that phosphorus from the systems will contribute to water quality problems and create an imminent threat to public health and safety and the environment. Ultimately, it is the absence of a fully implemented, comprehensive management program addressing each of these issues that limits the reliability and effectiveness of such systems. The potential for health and water quality problems from poorly managed systems is increased.

Benefits of a management program are accrued by both the municipality and the property owners. These are discussed below.

Protection of public health and local water resources

Although currently not quantified, SSTS failures resulting in yard backups have been recognized as a public health hazard and water quality issue for many years. Improved management practices will minimize the occurrence of failures by ensuring that pollutants are adequately managed and treated.

Groundwater conservation and water quality=

A properly functioning SSTS contributes to ground water recharge and protect the quality of groundwater and nearby water resources. Due to the number of failing septic systems still in operation, conversion to regional sanitary services can often result in improved water quality within nearby water resources.

Preservation of tax base

A series of well-managed SSTS can prevent small communities from needing to finance the high cost of centralized sewers. If small communities exhaust their tax base, at the expense of other public safety and education programs, to pay for sewers, they may then need to encourage growth in an effort to pay for the systems.

Life-cycle cost savings

There is indication that in many cases management may pay for itself in terms of lower failure rates and alleviation of the need for premature system replacement. This payoff will depend on the types of systems employed and the management program chosen.

Program development and implementation

EPA’s Handbook for Managing Onsite and Clustered (Decentralized) Wastewater Treatment Systems describes a step-by-step approach to developing a community management program for decentralized wastewater systems. The handbook is intended to improve the performance of individual and clustered treatment systems through better planning, design, siting, installation, operation, maintenance and other activities. It includes specific community examples, gives an overview of the elements essential for sound management of these systems, and provides links to extensive resources (articles, publications, web sites, databases, software, and government programs) for more thorough investigation of particular topics or elements of management. The handbook also includes the necessary steps for developing or enhancing a decentralized wastewater management program.

Management models

EPA’s Voluntary National Guidelines for Management of Onsite/Decentralized Wastewater Systems (Guidelines) are a set of practices recommended to raise the level of performance of onsite/decentralized wastewater systems through improved management programs. Five separate model programs are presented as a progressive series. Management requirements of wastewater systems become more rigorous as the system technologies become more complex or as the sensitivity of the environment increases. Each model program shares the common goal of protecting human health and the environment. Each model approach includes program elements and activities needed to achieve the management objectives. The Guidelines address the sensitivity of the environment in the community and the complexity of the system used. An overview of the management models are summarized below.

  • Management Model 1 Homeowner Awareness - Individual property owners in areas of low environmental sensitivity must be aware of their treatment systems and understand proper maintenance schedules. This program is adequate where treatment technologies are limited to conventional systems that require little owner attention. To help ensure that timely maintenance is performed the regulatory authority mails maintenance reminders to owners at appropriate intervals. This model is a starting point for enhancing management programs because it provides communities with a good database of systems and their application for determining whether increased management practices are necessary. In Minnesota all owners of new systems receive a specific and detailed management plan for their system. These management plans are developed by the system designer.
  • Management Model 2 Maintenance Contracts - This model focuses on the need for maintenance contracts for systems with complex designs and systems employed to enhance the capacity of conventional systems to accept and treat wastewater. Contracts with qualified technicians can be used to ensure proper and timely maintenance of all types of systems, but most commonly are used for large complex systems.
  • Management Model 3 Operating Permits - Sustained performance of treatment systems is critical to protect public health and water quality. Limited-term operating permits are issued to the owner and are renewable for another term if the owner demonstrates that the system is in compliance with the terms and conditions of the permit. Performance-based designs may be incorporated into programs with management controls at this level. In Minnesota, management model 3 is used for all new systems that incorporate pre-soil treatment devices.
  • Management Model 4 Responsible Management Entity (RME) Operations and Maintenance Under this model, the operating permit is issued to an RME instead of the property owner to provide the needed assurance that the appropriate maintenance is performed. The property owner is responsible for system operations.
  • Management Model 5 RME Ownership - In contrast to model 4, under this model, treatment systems are not only operated and maintained by the RME, but also owned by the RME, which removes the property owner from responsibility for the system. This program is comparable to central sewerage and provides the greatest assurance of system performance in the most sensitive of environments. Some sanitary districts in Minnesota are operating SSTS under this management level.

Maintenance considerations

Initial adoption of a management program requires an investment in training for the plan developer (or fee for a consultant). MS4’s must also consider the enforcement, including staff training and equipment maintenance requirements. In addition, periodic review and update of the management program would be required.

Typical cost

MS4s must recognize the likelihood that both the regulatory authority and the property owner will face increased costs in improving management practices and programs. The cost impacts may increase as the level of management increases; however, trade-offs exist. Costs incurred by the regulatory authority and/or management entity may be offset by increased permit fees and more efficient data management tools, while the costs to the property owner may be offset by reduced repair and replacement costs, avoidance of environmental restoration costs, and increased property values and quality of life.

This page was last edited on 23 January 2023, at 22:49.