Last Revised 1/18/01
On-Site Wastewater Treatment and Disposal Systems
The Nature of the Problem
Outside of the City of Ithaca, the Village of Cayuga Heights, and portions of Towns of Dryden and Lansing, residents and businesses within the watershed of Cayuga Lake are served by on-site wastewater disposal systems. This decentralized treatment is very common in New York State and throughout the United States. Nationally, about one-fourth of the total population is served by onsite wastewater systems, and about 37 percent of new construction employs this type of treatment. Small, rural communities represent about 10 percent of the total wastewater need in the country, but decentralized systems are not limited to these areas, since more than half of onsite systems are found in metropolitan areas.
The septic tank is an underground, watertight vessel installed to receive wastewater from the home. It is designed to allow solids to settle out and separate from the liquid, to allow for limited digestion of organic matter, and to store the solids while the clarified liquid is passed on for further treatment and disposal (EPA 1999). In the Cayuga watershed, effluent wastewater typically leaves the tank and is distributed to a subsurface soil absorption area (the leach field). Here the clarified effluent gradually seeps in to the surrounding soils where biological and physical reactions further reduce the concentrations of nutrients, microorganisms, and oxygen-demanding material.
When correctly installed and maintained, septic tank/soil absorptions systems are an effective way to treat and dispose of domestic wastewaters. Nevertheless, even the best systems are designed to release contaminants into groundwater. Siting, design, installation, operation, and maintenance must be focused on reducing the environmental impact of the release. To avoid contamination of drinking water systems and other problems, soil absorption systems must be situated at prescribed distances form wells, surface waters, springs, property boundaries etc. In New York, State and County Health Departments have jurisdiction to approve septic systems.
There are no site-specific data regarding the overall performance of on-site wastewater disposal systems within the Cayuga watershed. EPA has estimated that anywhere from 10 to 30 percent of onsite systems are failing annually. Failure of systems to adequately treat wastewater may be related to inadequate siting, improper installation, or poor operation and maintenance. A critical factor in optimal system performance is the depth of unsaturated soil beneath the soil absorption field. Based on the soil suitability maps for the watershed, large portions of the unsewered area have soil and slope characteristics that present a challenge to proper operation of on-site wastewater disposal systems.
While it is difficult to measure and document specific cause-and-effect relationships between onsite systems and the quality of Cayuga Lake and its tributaries, there is little doubt that improperly operating systems can be significant contributors to major water quality problems. States report failing septic systems as the third most important source of ground water contamination. In a recent survey of ocean beaches, EPA reported that septic systems were a significant pollution source for more than one-third (36 percent) of the water-quality impaired miles of shoreline. The discharge of partially treated sewage from malfunctioning on-site septic systems was identified as a principal or contributing factor in 32 percent of all harvest-limited shellfish growing areas, resulting in considerable economic impact on the shellfish industry. Onsite wastewater systems have also added to the overabundance of nutrients in ponds, lakes and coastal estuaries, leading to over-growth of algae and other nuisance aquatic plants. Finally, septic systems are a factor in the contamination of drinking water sources. EPA estimates that an estimated 168,000 viral and 34,000 bacterial illnesses occur annually as a result of drinking water systems that rely on ground water. Malfunctioning septic systems are identified as a potential source of this microbial contamination (EPA 1999). The PWL for Cayuga Lake lists septic effluent as a source of nutrients contributing to impairment of the northern segment.
Symptoms of a failing septic system can include strong odors, ponding of improperly treated wastewater, or backup of wastewater into the home. Unfortunately, substandard operation can persist for years without obvious symptoms. Solvents, poisons, and other household chemicals should not be allowed to enter a septic system, for these chemicals can kill the microbial community that has developed to treat the waste. Products marketed as septic tank cleaners are organic solvents that can kill the microbial community and contaminate receiving waters.
Goal: To reduce nutrient and pathogen impacts from septic systems on surface and groundwater in the Cayuga Lake watershed.
Both New York State and the EPA maintain compendia of management practices for alternative on-site wastewater treatment systems. The "On-site Wastewater Treatment Systems Management Practices Catalogue" is prepared by the On-site Wastewater Treatment Systems Management Practices Subcommittee of the New York State Nonpoint Source Management Practices Task Force (revised December 1996).
New York Catalogue of Practices. Management practices are categorized as operational, or structural, depending on their purpose, function and design. Operational practices involve changes in the management or design of the system. Examples of operational practices include: public education on materials that should not be disposed of in the system, conservation measures such as low flow toilets that reduce water use, and guidelines for inspection and maintenance of the system.
Structural measures usually require engineering design. In the NY catalogue, the structural practices generally describe a treatment system.
Conventional Systems. Design specifications for the following conventional systems are included: absorption field system, gravelless absorption systems, deep and shallow absorption trenches, cut and fill systems, absorption bed systems, and seepage pits. There are slight differences in site requirements for depth of percolation test hole, minimum depth of in-situ usable soil, minimum separation between the trench bottom and groundwater, soil mottling, bedrock, or impermeable strata.
Septic tanks and standard absorption fields are the standard practice. Aerobic systems (systems with a chamber where air is injected into the wastewater to promote aerobic decomposition processes) can be used on sites where unsuitable soils or high groundwater conditions have caused traditional systems to fail. This technology may also be used on small lots. The liquid effluent from an aerobic system, which has lower concentrations of suspended solids and oxygen-demanding material, is then discharged to a standard absorption field. The maintenance requirements for an aerobic system are much higher than for a standard septic tank, due to the motors, aerators and filters.
Gravelless absorption systems are also considered conventional systems. These can be plastic or concrete chambers of various designs or large corrugated plastic pipes wrapped in geotextile fabric. This design does not overcome site limitations, and is used in areas where gravel is not economically available.
Deep absorption trenches are used in sites where a thick layer of impermeable soil overlies more suitable soil. This conventional system is excavated through the impermeable layer and backfilled with aggregate or coarse sand. Because of the depth of discharge, there is less uptake of treated wastewater by site vegetation. In contrast, shallow absorption systems (also considered conventional) are used on sites where there is at least four feet but less than four feet of usable soil and/or separation to groundwater.
Cut and fill systems refer to standard absorption trench systems installed in sites where impermeable soil overlays a permeable layer. While similar to deep absorption trenches, these systems are considered to be more effective provided that the underlying soil is not compacted during installation.
Seepage pits are considered the least preferred of the conventional treatment systems in the NY catalogue. They may be adequate for treating very small flows on sites with inadequate land resources for a standard absorption field.
Alternative Systems. There are three alternative systems listed in the NY catalogue. Raised systems are conventional absorption trench systems constructed in permeable fill placed above the ground surface. The leach field is constructed entirely in the fill. Use of this technology can enable a properly functioning wastewater disposal system on a site that could not meet horizontal or vertical separation distance to limiting conditions.
Another alternative system is the elevated sand mound. A mound system is defined as a pressure-dosed absorption system that is elevated above the original soil surface in a sand fill. The system consists of a septic tank (or aerobic tank), dosing chamber, and the elevated sand mound. Elevated sand mounds may be appropriate for sites with native subsoils that do not transmit water or insufficient depth of permeable soil above limiting conditions (high groundwater or porous bedrock). It is important to note that the elevated sand mound is not acceptable within the watersheds of New York Citys water supply.
The third alternative system is the intermittent sand filter. This is a biological and physical treatment process consisting of a filter bed of carefully graded media (commonly sand). The surface of the bed is periodically dosed with wastewater from the septic tank. Liquid passing through the sand filter is then discharged to a mound absorption system. This system can achieve high levels of pollutant removal due to the double filtration of the sand filter and the downstream mound. Best suited for large lots, the intermittent sand filter can be installed where site constraints of shallow or slowly permeable soils limit applicability of conventional systems. These systems will generally not be approved for use within the watersheds of New York Citys water supply.
EPA Catalogue of Practices. Through the Environmental Technology Initiative, EPA has compiled a series of fact sheets describing innovative and alternative wastewater technology projects in both small and large communities. These alternative technologies were funded through the agencys former Construction Grants Program.
The fact sheets were designed to be used as a preliminary process selection tool in identifying an appropriate wastewater technology/practice for single-family residences, clusters of homes, subdivisions, or communities. Two versions of fact sheets are available for each technology: a four-page technical overview for engineers, manufacturers, regulators, and other technical audiences and a two-page general overview for elected officials and the public. Both fact sheets describe how the technology works, its advantages and disadvantages, operation and maintenance, and costs. The technical fact sheets also include design/process specifications, performance characteristics, and application results in the form of case studies.
Technical and general fact sheets are available on the following technologies / practices:
Fine Bubble Aeration
Trickling Filters: Achieving Nitrification
Intermittent Sand Filters
Recirculating Sand Filters
Composting Toilet Systems
Low-Pressure Pipe Systems
Sanitary Code of the Cayuga County Health Department
Cayuga County On-Site Wastewater Inspection
State and Local Workshops and Training
Public Health Law - Article 11 of the Public Health Law and Title 15 of the Environmental Conservation Law provide for review of water supply and sewerage services by the state health department (or county health department where they exist) for tracts of land divided into five or more parcels of five acres of less.
Improvements in the design, siting, operation, inspection, and maintenance of on-site wastewater treatment systems are needed to protect and maintain the integrity of the water resources. This is an area of active research nationally. New technologies are being applied to onsite systems, resulting in higher treatment levels, greater reliability and more flexibility than ever before. In many communities onsite and decentralized systems are the most appropriate, least costly treatment option, and they allow maximum flexibility in planning for future growth.
EPA's Report to Congress identified five major barriers to the successful implementation of decentralized wastewater technologies. These include: (1) misinformation and limited public knowledge about onsite systems; (2) legislative and regulatory constraints; (3) lack of system management; (4) existing engineering practices; and (5) restricted access to funding. Most of the EPA-sponsored activities have been targeted toward overcoming one or more of these barriers.
Some funding opportunities are listed below:
Clean Water State Revolving Fund. EPA provides over $1 billion of funding annually to the States, who manage individual revolving loan funds for wastewater and other water quality projects. These programs provide loans at low or zero interest, with repayment periods of up to 20 years. Onsite and clustered wastewater systems are potentially eligible for funding, and loans in some cases can be made directly to individual homeowners or non-profit organizations through local banks. Loan funds can also be used in some cases to fund the startup of an onsite management program, including obtaining permits, payment of legal fees, and capital costs such as pumper trucks, monitoring equipment and purchase of buildings. Terms and availability vary by State.
Non-Point Source Pollution Grants. Under Section 319 of the Clean Water Act, EPA provides grants annually to States for controlling nonpoint sources of pollution, such as agricultural runoff, mining activities and malfunctioning onsite septic systems. In States where onsite systems have been identified as a significant source of non-point pollution, the 319 funds may be used to construct, upgrade or repair onsite systems.
U.S.D.A. Rural Utilities Service. The Rural Utilities Service of the U.S. Department of Agriculture (RUS) provides water and waste disposal loans and grants in rural areas and towns with 10,000 or fewer residents. Grants may be made for up to 75 percent of eligible project costs in some cases, and RUS also guarantees water and waste disposal loans made by banks and other institutions. RUS funds are available to public entities including special-purpose districts and non-profit organizations. Decentralized wastewater systems are eligible for funding, but must be owned and managed by the borrower/grantee.
U.S. Department of Housing and Urban Development. This agency provides funds to the States, who administer Community Development block grant (CDBG) programs. These programs provide grants to communities for various purposes, including rehabilitation of residential and non-residential structures, construction of public facilities, and improvements to water and sewer facilities.
Voluntary Management Guidelines.
Under the Clean Water Action Plan, EPA committed to developing voluntary national guidelines for decentralized wastewater management systems that address siting, performance, design and maintenance needs and requirements. Voluntary "management guidelines" have been developed in draft form, and will be finalized following a public comment period. The guidelines will help communities meet water quality and public health goals and provide a grater range of options for cost-effectively meeting wastewater needs.
In the management guidelines, five incremental levels of management are presented in a progressive series of "model programs," beginning with basic information collection and maintenance awareness, and moving up to the highest level of management, in which onsite systems are owned and managed by a utility. Each of the model programs share the common goal of ensuring that human health and the environment are protected. Each model program includes a set of management objectives, and an accompanying set of associated elements and activities targeted at the satisfactory achievement of the objectives. Program elements include planning, siting, design, construction, operation and maintenance, residuals management, certification and licensing, education and training, inspections, monitoring, and record-keeping.
The model programs are a benchmark for a state, tribal or local unit of government to: 1) identify its management objective, 2) evaluate whether its current program is adequate; and 3) determine both an appropriate management program, and the necessary program enhancements to achieve its management objectives and public health and environmental goals. EPA recognizes that states, tribes and local governments need a flexible framework and guidance to best tailor their programs to the specific needs of the community, and to the institutional capacity of the regulatory authority. These model programs are not intended to supercede existing federal, state, tribal and local laws and regulations, but rather be a complement to them.
The following is a discussion of the various recommended levels of management:
Model Program 1 - System Inventory and Awareness of Maintenance Needs: EPA recommends this as a minimum level of management. Model Program 1 applies where conventional onsite systems, owned and operated by individual homeowners, are sited in areas of low environmental sensitivity, i.e., no site or soil restrictions such as drinking water wells in close proximity or a high groundwater table. Model Program 1 is intended to raise the local regulatory agency's awareness of the location of systems, raise homeowners' awareness of basic system needs and ensure homeowner compliance with basic maintenance requirements. This Program also serves as a starting point for communities to have basic data that will help them determine if higher management levels are necessary.
Model Program 2 - Management Through Maintenance Contracts: EPA recommends this program where sites with limiting conditions, such as small lot sizes, or restrictive soil conditions (i.e., slowly permeable soils, shallow soils with limited treatment capacity or high ground water table) are encountered in a small portion of a community. These limiting conditions require improved effluent dispersal to the soil or additional treatment units such as media filters or aerobic treatment units, and are typically operated through contract with equipment vendors. Model Program 2, therefore, sets higher expectations for a regulatory program and for educating homeowners.
Model Program 3 - Management Through Operating Permits: Recommended by EPA in situations where the receiving environment indicates a need for advanced levels of treatment, such as an unconfined aquifer used as a drinking water supply or a fish spawning area. Model Program 3, consistent with the increasing risk, recommends setting measurable performance standards and ensuring compliance by issuing renewable operating permits which indicate specific performance criteria to be achieved. The regulatory agency monitors these systems for compliance with the performance criteria.
Model Program 4 - Utility Operation and Maintenance: Appropriately applied where engineered designs, such as aerobic treatment units, are required to overcome site, soil or environmental conditions that are not conducive to conventional or alternative onsite technology. Frequent monitoring and maintenance is needed in these situations. Model Program 4 recommends that operation and maintenance be provided by a public/private utility that is responsible for system performance to ensure the maintenance needs are met.
Model Program 5 - Utility Ownership and Management: Represents the management needs of a more complex program where a very high level of control is required due to public health or environmental concerns. Model Program 5 includes the public/private utility as the designated management entity that both owns and operates the onsite systems in a manner analogous to a publicly owned wastewater utility. This program is similar to the utility concept in Model Program 4. Under this level of management the utility maintains total control of all aspects of management, not just operation and maintenance.
Summary Of EPA Guidelines For Management Of Onsite/Decentralized Wastewater Systems
|Model Program||Typical Application||Management Objectives||Benefits||Limitations|
|1||Areas where conventional onsite systems are adequate to protect water quality and public health||SYSTEM INVENTORY AND AWARENESS OF MAINTENANCE NEEDS
To ensure conventional onsite/decentralized systems are sited and installed properly in accordance with appropriate state/local regulations and codes; and are periodically inspected, maintained, and repaired as necessary. Regulatory agency is aware of the location of systems and periodically provides owners with operation and maintenance information.
|Relatively easy and inexpensive to implement and maintain. (Programs are based upon conventional, prescriptive system designs that rely upon minimum site criteria and system design requirements promulgated in codes.)||No mechanism to ensure operating compliance of systems.
No mechanism to identify failures when they occur.
Limits building sites to those meeting prescriptive requirements.
|2||Areas where sites are marginally suited for conventional systems, requiring alternative, enhanced treatment systems to be implemented||MANAGEMENT THROUGH MAINTENANCE CONTRACTS
To allow the use of more complex mechanical treatment options through the requirement that maintenance contracts be maintained between the owner and equipment manufacturer/ supplier or service provider over the life of all systems.
|Reduces the risk of failure through the requirement for routine maintenance of mechanical components by skilled personnel.||State/local agency may have difficulty tracking and enforcing compliance with the maintenance requirements and/or contract.|
|3||Moderately environmentally sensitive areas, which require engineered designs to meet specific performance requirements based on site characteristics||MANAGEMENT THROUGH OPERATING PERMITS
To allow the use of onsite/decentralized treatment on sites with a greater range of characteristics than allowed by prescriptive codes through the establishment of specific and measurable performance requirements, renewable operating permits, and regular compliance monitoring reports.
|Increases the range of sites suitable for
Reduces the risk of performance failures by levying that performance requirements be met to renew limited term operating permit.
|Addresses problem where owner may not manage
system adequately and continues to operate a non-compliant system.
Needs a higher level of technical/engineering expertise to implement
|4||Areas where there is existing or potential impairment of receiving waters and the environmental and technology concerns require greater assurance of adequate operation and maintenance.||UTILITY OPERATION AND MAINTENANCE
To ensure that onsite/decentralized treatment systems consistently meet their performance requirements through the creation of public/private utilities that are responsible for the performance of systems within the service area, but do not own the systems.
|Responsibility for operation and maintenance
is transferred from the owner to a professional utility that has an economic incentive to
comply with the operating permit.
Routine inspections may identify obvious structural problems before system failure occurs.
|Additional regulatory oversight needed to evaluate and ensure that the utility is technically and financially viable.|
|5||Existing or potential impairment of highly sensitive areas such as sole source aquifers, critical aquatic habitats, outstanding natural resource waters, or other areas where highly centralized management is needed to ensure reliable, long-term system operation and maintenance.||UTILITY OWNERSHIP AND MANAGEMENT
To provide professional management of the siting, design, construction, operation, maintenance, etc. of onsite/decentralized systems through the creation of public/private utilities that own and manage systems within the service area.
|Simulates the municipal model of central
sewerage by transferring all responsibility from the property owner to a professional
entity, reducing risk of non-compliance to lowest level.
Allows effective area-wide wastewater planning through integration of onsite/decentralized systems with conventional sewerage.
Reduced number of permits requiring oversight by regulatory agency.
|Property owner may oppose utility's easement
to property for the system.
Additional regulatory oversight needed to evaluate and ensure that the utility is technically and financially viable.
Recommended New Practices:
Foster communication between local code enforcement officers, design professionals, and representatives of State and County Health Departments responsible for evaluating alternative and innovative technologies.
Hold regular educational/training forums for the following:
Contractors and others associated with septic system design and construction.
Municipal boards (e.g. elected, zoning, and planning)
Encourage development of sanitary public and private water supplies.
Assist as appropriate in the development of public wastewater collection and treatment projects.
Develop more complete assessment of the wastewater treatment and water supply needs of problematic locales.
Promote appropriate maintenance practices in all phases of program implementation.
Develop and maintain a system to review and document interpretations of the state sanitary codes and their relationship with the uniform fire prevention and building code.
Proposed Model Local Law On-Site Individual Wastewater Treatment Law
Use Sanitary Code of the Cayuga County Health District and related on-site waste water inspection program as a model for all counties in the Cayuga Lake Watershed
Use Home*A*Syst Program as a model for education and assessment of on-site systems
Develop funding source
Use of interns for personal resident surveys (especially lakeshore) and book distribution
Conduct pollution checklist and assessments
Is there a potential source of pollution (manure, fuel tank, septic system, etc.) located on your property or within 100 feet of a well, stream or lake?
Has it been more than 3 years since you had your septic tank inspected and/or pumped? (use Self Assessment)
Home*A*Syst Guide Chapter - Household Wastewater: Septic Systems and Other Treatment Methods
Education Workshop - Household Wastewater Systems
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CLW IO 2004