EPA Case Studies

Outdated, neglected, or nonexistent wastewater systems posed a public health risk to the 800 citizens of Peña Blanca, New Mexico. Open cesspools and seepage pits emptied into yards and irrigation canals. Surveys revealed that 86% of the individual wastewater systems needed repair or replacement. Residents rejected a proposed centralized sewer system that would have cost $3.1 million.    

The community opted to repair or replace 133 of the existing 185 treatment systems with the water and sanitation district serving as the operator/manager of the upgraded and new facilities. 

"The decentralized wastewater option was less than half of the projected cost of central sewage treatment for the 133 homes served by repaired or replaced systems. Sewage surfacing and cesspool discharges throughout the community no longer occur. Post-construction groundwater monitoring found nitrate levels at 1 mg/L or less in the project area, far below the 10 mg/L standard for groundwater used as drinking water."

The community around Otter Tail Lake in western Minnesota saw a decline in lake water quality. An environmental assessment revealed that substandard wastewater systems, untreated sewage discharges to surface waters and intensive shoreline development contributed to high levels of phosphorus in the lake, causing elevated algae growth and an overall decline in water quality.

The community formed a management district to identify and repair/replace malfunctioning systems and manage the wastewater treatment systems of four townships situated on six area lakes.

After the program’s inception in 1984, the OTWMD upgraded 850 treatment systems. The district installed 16 clustered systems for 260 connections and repaired or replaced 590 other treatment systems. The district also serviced a total of 350 other systems, including full inspections, septic tank pumping and installation of new tank risers and covers. In the past decade, the district has replaced or repaired only 17 systems (out of nearly 1,500).  

The district’s actions resulted in documented water quality improvements. For example, surface water monitoring of the lake has revealed declining phosphorus and algae concentrations and overall improved water quality. Nitrate concentrations have dropped from 1 mg/L to approximately 0.2 mg/L; Secchi depth has increased from 2.4 feet to about 4 feet.

Approximately 20,000 residents in the Keuka Lake watershed rely on groundwater and the lake for their drinking water. Nearly all of the residents in the watershed also depend on individual wastewater systems that are densely positioned and that discharge to the soil for treatment. However, testing revealed that poorly maintained individual onsite systems were contributing excessive levels of bacteria to the lake and contaminating drinking water wells. 

Eight municipalities formed a regional watershed cooperative that implemented a uniform permitting and inspection program to identify and repair or replace malfunctioning treatment systems. As a result, Keuka Lake’s water quality ranks among the highest of the water bodies in the Finger Lakes region. 

After the program’s inception in 1984, the OTWMD upgraded 850 treatment systems. The district installed 16 clustered systems for 260 connections and repaired or replaced 590 other treatment systems. The district also serviced a total of 350 other systems, including full inspections, septic tank pumping and installation of new tank risers and covers. In the past decade, the district has replaced or repaired only 17 systems (out of nearly 1,500).  

Water quality monitoring results indicate very good lake conditions, though runoff from stormwater and agricultural sources after storm events can result in high bacteria levels. The relatively clear water in the lake contains low nutrient levels and supports excellent fisheries. Monitoring results from 2005–2009 show lake water quality improving or holding steady for nearly all parameters. The local lake association attributes this progress, in part, to the septic system inspection program.  

Carmody Client

The Auburn Lake Trails Subdivision in California was developed during the 1970s and 1980s as a recreational community near Auburn Lake, with more than a 1,000 relatively small lots in an area with shallow, low-permeability soils and steep topography. When developers discovered that local soils could not treat the waste adequately to protect water resources upon full build-out, they proposed building a centralized sewage collection and treatment system. However, it was opposed by residents as too costly.  

The community authorized the Georgetown Divide Public Utility District (PUD) to design and manage conventional and advanced treatment individual and clustered wastewater systems. The PUD developed an approach that links the required performance levels for treatment systems to health and environmental risk and where maintenance and monitoring schedules depend on the system type.  

Of the 134 septic tanks inspected in 2009, five were found to be defective and were replaced. The inspection and management program has prevented onsite system malfunctions and has been an effective alternative to costly centralized sewers. The annual inspection of all systems provides for early detection of problems that could lead to a malfunction. Water quality sampling since 1985 has found no degradation of groundwater or surface water. 

Of the 999 systems in the subdivision, most of them (63%) are more than 20 years old, and 36% are more than 30 years old. Only 10 systems have malfunctioned in the last 25 years; malfunctions were mostly due to tree roots, hydraulic overloading and other problems such as improper grading, construction activities, etc. 

By identifying the location of systems and ensuring their proper operation, the community can make smart decisions to accommodate residential development. 

  Carmody Client 

Jamestown is a small, island town dependent on private drinking water wells and individual wastewater systems. Poorly maintained onsite wastewater systems on undersized lots with high seasonal water tables were affecting groundwater quality. Studies revealed that 32% of the wastewater treatment systems in the area were contributing to nutrient and pathogen problems in private water wells (Legislative Press and Public Information Bureau, 2006). 

Jamestown adopted an ordinance requiring routine inspections of individual wastewater systems. A High Groundwater Table District also guides future development to protect drinking water quality. 

To date, 94% of all septic systems have had an initial maintenance inspection. 

Of the systems inspected: 

      - 35 failed (2%)  

     - 85 (5%) were found to be  substandard systems (e.g.,  cesspools, systems with steel  tanks)  

     - 1,488 passed (93%) Since 2003, 50 systems have been subject to repair/replacement actions    

        initiated by the town. 

Property owners are responsible for ensuring that their system is operating properly and that it is maintained in good repair. Systems that do not meet applicable performance requirements can be subject to a repair or replacement order. Addressing malfunctioning systems helps to reduce nitrogen and pathogen pollution that pose threats to Jamestown’s drinking water sources.

Rivers and streams of the Albemarle Region of North Carolina are nutrient-sensitive and require nutrient input controls such as upgrades for wastewater treatment plants and septic systems. Both strategies are being pursued by state and local officials. Much of the area is unsuitable for conventional gravity-flow individual systems due to low-permeability clay soils and high water tables. In past decades, these limitations prompted the extensive use of sand-lined trench leaching systems in the region. A 1991 study found that 30% of those systems were malfunctioning and posing risks to groundwater and surface water quality.  

Local governments authorized a regional management entity to inventory and monitor individual wastewater systems, improve system management, and develop site-specific design criteria for new and replacement systems incorporating advanced treatment technologies.  

Local officials note that the management entity has prevented system malfunctions through more rigorous design, inspection, and operation/maintenance requirements. In the early 1990s, estimates of system malfunctions ranged as high as 30%. During 2007–2008, the program inspected 2,153 of the 4,240 systems under its management purview, and fewer than five of the newly installed systems were found to be malfunctioning. 

New system installations and increasing the number of properly functioning systems through inspections will help to reduce nutrient pollution in the Albemarle watershed. 

During the past three decades, the population of Fairfax County has grown to more than one million people. With sanitary sewers at or near capacity, the number of individual wastewater systems began to multiply, eventually rising to more than 24,000. Inappropriately sited, improperly designed, and/or poorly managed individual systems have the potential to contribute to the pollution and degradation of the county’s 900 miles of perennial and intermittent streams and a number of freshwater lakes and ponds. 

Fairfax County adopted an ordinance requiring routine pumping of septic tanks every five years and alternating drainfields and drainfield reserve areas to ensure system performance.  

 A recent study found that the average malfunction rate for systems in the county was only 2.1% of the 15,401 systems reviewed. In addition, many systems thought to have outlived their life expectancy are still functioning satisfactorily. 

The creation of a database for system inventory has allowed the county to track septic tank pump-outs and categorize all systems according to system type, greatly assisting the enforcement of existing codes and regulations. The use of alternating drainfields has increased the average lifespan of sewage disposal systems. 

The five-year pump-out requirement has resulted in better maintained systems and the identification of system malfunctions that would otherwise go undetected. As a result of these measures, fewer owners are facing costly major repairs or system replacements. 

Through its program, Fairfax County now better understands and manages its many onsite systems even in light of a fast-growing population. 

Potential public health threats posed by bacteria and viruses in surface waters prompted the Hamilton County Board of Health to investigate some 10,000 mechanized onsite wastewater systems. The inspections revealed that 3,400 (34%) of the systems—mostly serving individual homes—were substandard or malfunctioning.  

The Hamilton County General Health District upgraded its onsite wastewater program to include operating permits and routine inspection requirements to maintain system performance.  

The program has identified and required the repair/replacement of thousands of noncompliant systems, many of which were discharging poorly treated sewage to area streams or directly to the ground surface. Since its inception, more than 2,300 malfunctioning systems have been replaced and over 32,000 system repairs have been completed. 

Studies conducted in 2000 and 2001 found a 54% improvement in suspended solids, a 36% improvement in biochemical oxygen demand, and a 60% improvement in fecal coliform over baseline data collected five years earlier. 

In addition, mechanical system malfunctions dropped from a high of 44% to a consistent and predictable rate of around 18%. Nonmechanical system malfunctions were over 23% in 2003 and have currently dropped to 2.6%. Onsite sewage treatment system nuisance complaints dropped from 371 in 2003 to 258 in 2009. 

Residential growth is a challenge in unsewered resort communities like Lake Panorama, Iowa, due to the need to protect lake water quality from septic system impacts. Lake Panorama is one of the largest private lake resort communities in Iowa. Installing conventional, soil-discharging wastewater systems is difficult in this community because of steep slopes, ravines, low-permeability soils, and small and oddly shaped lots.  

The community created a management district to accommodate growth and protect water resources through the use of advanced, clustered, and innovative onsite wastewater treatment systems. 

The management programs for Lake Panorama have likely provided ongoing protection for Lake Panorama as indicated by water quality monitoring results. Bacteria concentrations at the Lake Panorama outlet are lower than that of other reaches of the Raccoon River system. Over the past few years, the district has logged only one aeration treatment unit malfunction annually, out of more than 1,000 homes on line. Additionally, system costs—though a bit higher initially—are lower than previous totals overall, as costs focus more on routine maintenance than replacement of malfunctioning systems. 

The communities of Lake Panorama now better understand their onsite systems and can manage these systems appropriately to accommodate growth in the area.  

In 1995, Missouri adopted more stringent public health regulations for individual systems on lots of three acres or less. To comply with those regulations, property owners in Phelps County needed to upgrade their individual systems. The need to upgrade systems was underscored by the fact that local lenders would not make loans on houses that were not in compliance with state rules.  

County leaders and the local water supply district expanded services to allow the water district to own and operate decentralized systems that provide affordable and sustainable wastewater treatment. 

The county now manages eight clustered systems with septic tank effluent pumps that serve 415 residential units, rather than 450 individual septic systems. The clustered systems serve as upgraded systems for the homes that previously had malfunctioning systems. Actual effluent quality for the clustered systems ranges from 4 to 9 mg/L for biochemical oxygen demand and 1 to 8 mg/L for total suspended solids. Fecal coliform levels have been in the range of 10 colony-forming units per 100 milliliters of effluent.

In addition, local officials believe that the elimination of hundreds of old septic system leachfields has improved groundwater quality, based on the higher quality effluent being discharged from the new systems. 

Just a two-hour drive from San Francisco, The Sea Ranch community extends 10 miles along the northern California coastline. Built in the 1960s and 1970s, many of the homes relied on individual wastewater systems. Half of the homes were built in areas susceptible to high groundwater, with coastal meadows and terrace soils causing wastewater system malfunctions. Aging infrastructure, challenging conditions, and poor system maintenance in the upscale resort community posed a threat to local and coastal waterways. As a result, a moratorium was placed on future development in the community.  

Sonoma County, the California Water Resources Control Board, and The Sea Ranch community reached an agreement to improve performance and track compliance of new and existing wastewater systems by forming a wastewater management zone. The moratorium was lifted after the solutions were implemented. 

Surface and groundwater monitoring results have found no evidence of groundwater pollution associated with the hundreds of individual systems and two clustered wastewater systems in The Sea Ranch community. System malfunctions, such as the sewage surfacing and groundwater contamination that spurred the creation of the program no longer pose a significant threat due to routine operation, maintenance, and management procedures.