Operation and Maintenance of Sewer Systems
Other Operations that may be Regulated
Some tribal governments are responsible for designing, planning, constructing, financing, operating, and maintaining wastewater treatment plants. Other tribes may run regional wastewater treatment plants for service areas exceeding their reservation and enter into service contracts with regional authorities or individual users. In both cases, tribes are responsible for the conveyance systems that transport wastewater to the treatment plant and discharge stormwater runoff to nearby water bodies.
A publicly owned treatment work (POTW) consists of the wastewater treatment plant and a collection system that transports sewage to it. A collection system can be either of two types (or some combination of the two):
- Separate sewer systems that are designed to convey only municipal sanitary sewage and industrial wastewater.
- Combined sewer systems that are designed to convey stormwater runoff in addition to municipal sewage and industrial wastewater.
A third type of conveyance system - a municipal separate storm sewer system (MS4) - conveys stormwater runoff directly to nearby waters rather than to a POTW.
Overall, POTWs are responsible for collecting, treating, analyzing, and discharging wastewater received from separate sanitary or combined sewer systems, as well as for disposing of sewage sludge, or "biosolids," generated during the treatment process. A POTW must comply with its NPDES permit, including requirements for industrial pretreatment, compliance monitoring, and proper use or disposal of biosolids. A POTW is also responsible for laboratory operations, chemical storage and hazardous materials management, and vehicle and equipment maintenance.
Operation and Maintenance of Sewer Systems
A tribal government may be responsible for operating and maintaining three types of conveyance systems:
- Separate Sanitary Sewer Systems
- Combined Sewer Systems
- Municipal Separate Stormwater Systems
These systems may be regulated under the NPDES, pretreatment, or stormwater provisions of the CWA and 40 CFR Section 122.26. EPA generally is the permitting authority when NPDES or other permits are required in Indian country under federal environmental laws.
Sanitary Sewer Systems
Some tribal governments design, construct, operate, and maintain sanitary sewer systems to convey wastewater from homes and businesses to wastewater treatment plants. Some tribal governments install new sewer lines, clean blocked lines, repair leaky lines, maintain root control, repair manholes, operate and maintain pump stations, and conduct all maintenance activities necessary to prevent overflows and ensure that wastewater is conveyed to the treatment plant. Other tribes contract with outside suppliers to utilize sewer systems already in place in neighboring governments.
Maintaining sanitary sewer systems is a significant responsibility for tribal governments. Leaks or the infiltration of wastewater into the sewer system can occur through cracks and improperly sealed pipe joints. Overall, this "infiltration and inflow" (I/I) raises the volume of wastewater in sewers and lowers system capacity. During significant rainfall events, the sewer system cannot carry the excess wastewater, and flooding can occur. Diluted and untreated sewage can back up through manholes and into basements, spill into storm drains and creeks, and wash up onto beaches. To ensure maximum system capacity and to prevent these "sanitary sewer overflows" (SSOs), tribal governments must undertake active monitoring and preventive maintenance programs to identify and repair leaky sewer lines, as well as conduct any major upgrades or restorations.
Tribal governments that operate POTWs are required to report all overflows and flooding from either sanitary or combined sewage systems so that repairs can be made and preventive action can be taken, to minimize environmental and human health impacts.
SSOs, whether caused by excessive I/I, inadequate capacity, blockages, or equipment failure, impact the environment through the discharge of raw sanitary sewage. These discharges often result in direct human exposure to raw sewage, as well as surface and groundwater contamination. SSOs are unpermitted, illegal discharges under the CWA and may subject the tribal government to enforcement action by EPA or the tribal regulatory authority.
Combined Sewer Systems
Although limited in number, some tribal governments maintain combined sewer systems (CSSs) that are designed to carry sanitary sewage, industrial wastewater and stormwater runoff to the POTW. During periods of heavy rainfall or snow melt, the wastewater volume in a CSS can exceed the capacity of the system. CSSs, therefore, are designed to overflow and discharge excess wastewater directly to nearby water bodies. These discharges are called combined sewer overflows (CSOs).
Tribes with CSSs have operation and maintenance responsibilities similar to those for separate sanitary sewer systems, such as installing new sewer lines, cleaning blocked lines, and inspecting for and fixing leaks and infiltration. However, their most important activity is controlling CSOs, which contain not only stormwater, but also untreated human and industrial waste, toxic materials, and debris. EPA's Combined Sewer Overflows (CSOs) section on the NPDES page provides material on CSOs.
Municipal Separate Storm Sewer Systems
Although rare in Indian country, some tribal governments also are responsible for operating and maintaining municipal separate storm sewers (MS4s). MS4s are designed to convey stormwater from impermeable areas to bodies of water. In conveying stormwater directly to streams, rivers, and lakes, MS4s also transport oil, grease, pesticides, herbicides, dirt and grit, all of which have the potential to reduce water quality. Tribal government operations related to operating and maintaining storm sewer systems include clearing blocked sewer lines, preventing contaminants from entering the storm sewer system, constructing stormwater controls, and sampling and analyzing stormwater discharges. In addition, tribal governments can reduce the volume of silt and solids being transported to the sewer systems and reduce water contamination by cleaning streets, removing wastes, and cleaning sewer screens.
Medium and large MS4 operators are required to submit comprehensive permit applications and are issued individual permits. Regulated small MS4 operators have the option of choosing to be covered by an individual permit, a general permit, or a modified Phase I MS4 individual permit. Tribal governments responsible for operating and maintaining MS4s submit permit applications to EPA.
Sewer Line Repair/Replacement
Separate, combined, and storm sewer systems require repair to eliminate conditions that impede their ability to convey sewage and stormwater flows. Sewers and other collection system components, such as manholes, pump stations, and siphons, must be repaired or replaced to address structural failure, infiltration (leakage of groundwater into pipes), exfiltration (leakage of sewage out of pipes), and blockages. In combined sewers, flow regulators must be repaired when they fail to divert combined wastewater flows at the intended flow rates. Portions of a sewer system may need to be replaced to address inadequate capacity, which can result in separate sewer system overflows during periods of high flow. Repairs may involve replacing individual pipe sections, replacing entire sewer segments, or repairing existing sewers. Grouting leaking joints, lining existing sewers, and rebuilding or lining manholes and other structures all may be necessary.
Separate and combined sewer system repairs can impact the environment through the discharge of raw sewage around the line or system component being repaired. Repairs of separate, combined, and storm sewers also can affect the environment through erosion and sedimentation, which take place as a result of excavation, stockpiling, and backfilling, or through the discharge of sediment-laden water from the repair excavation. Guidance on sewer maintenance activities is often included in a tribal government POTW's NPDES permit.
Some tribal governments may be responsible for wastewater treatment. POTWs are responsible for the treatment, analysis, and discharge of wastewater received from sanitary or combined sewer systems, and the disposal of sludge generated from the treatment process.
Activities at a POTW may include:
- Operating and maintaining the plant to ensure that discharges meet the facility's NPDES permit requirements and limitations
- Overseeing a pretreatment program to prevent industrial discharges from causing interference or pass through, sludge contamination, or the plant to violate its permit
- Sampling and analyzing wastewater and sludge prior to discharge or disposal to meet NPDES monitoring requirements
- Managing biosolids from the treatment processes by landfilling, land application, surface disposal, incineration, or composting
- Maintaining records and submitting discharge monitoring reports (DMRs)
Because these activities could affect the environment, they may be subject to environmental regulations as indicated in the following list:
- Wastewater treatment process - CWA
- NPDES permit compliance - CWA
- Wastewater treatment plant effluent injection - SDWA
- Laboratory operations - CWA and RCRA
- Pretreatment program - CWA
- Biosolids management and disposal - CWA, RCRA, and CAA
- Chemical storage/hazardous materials management - EPCRA, CERCLA, and CAA
More information can be fount at EPA's information on wastewater treatment plants Web site.
Wastewater Treatment Process
Municipal wastewater (sewage) treatment is defined as primary, secondary, or tertiary according to the extent of pollutant removal and the mechanisms (physical, biological, or chemical) through which pollutants are removed. Primary treatment consists primarily of physical processes (settling or skimming) that remove a significant percentage of the organic and inorganic solids from wastewater. Secondary treatment depends on biological action to remove fine suspended solids, dispersed solids, and dissolved organics by volatilization, biodegradation, and incorporation into sludge. In addition, secondary treatment satisfies much of the oxygen demand of the pollutant(s). Tertiary (advanced) treatment uses a variety of biological, physical, and chemical treatment approaches to reduce nutrients, organics, and pathogens.
Tribes with wastewater treatment facilities may use "biogas," a product of anaerobic digestion, either offsite or within the plant to improve the energy efficiency of wastewater treatment processes. Biogas, a gas composed of methane, carbon dioxide, hydrogen sulfide, and other minor gaseous compounds, has about 60 percent of the heat value of natural gas. If the gas is not used, it can be flared, which may be regulated under the CAA.
NPDES Permit Compliance
Tribal governments with wastewater plant operations and/or a collection system (sanitary or combined) that conveys wastewater to a POTW are responsible for complying with applicable federal and tribal regulations. Proper operation and maintenance are critical for sewage collection and treatment because the environmental impacts from these processes can severely degrade water resources and, ultimately, human health. For these reasons, POTWs receive NPDES permits to ensure compliance with federal regulations.
NPDES permits, issued by EPA or an authorized tribal government, establish effluent limits, including type and quantity restrictions, and pollutant monitoring, record keeping, and reporting requirements. Each POTW (or other dischargers into surface water) that intends to discharge into the nation's waters must obtain an NPDES permit prior to initiating its discharge. To date, no tribe is authorized to issue NPDES permits.
To comply with the NPDES permit, tribal governments are responsible for implementing an NPDES monitoring program at their POTWs. To comply with the program, POTWs must collect samples of effluent discharges at the frequencies and locations specified in their permits and submit monitoring reports to EPA or a tribe that is authorized to administer the NPDES program. Sampling and analysis are conducted to verify that the amounts and types of pollutants discharged from wastewater treatment systems meet the NPDES permit limits. The NPDES permit specifies the parameters that must be monitored, which vary by plant. The primary parameters in NPDES permits for POTWs include flow, biochemical oxygen demand (BOD), pH, fecal coliform, residual chlorine, and suspended solids. A NPDES permit may include other parameters, such as bioassay toxicity tests and metals.
If a POTW meets the NPDES permit requirements, the systems usually are operating properly. Failure to comply with permit requirements can result in permit suspension, increased monitoring requirements, increased inspections, and/or issuance of fines or other penalties by EPA or the relevant tribal government regulatory agency.
Large Capacity Septic Systems
Some tribal facilities rely on on-site wastewater treatment systems and large capacity septic systems to treat wastewater, facilities with on site systems may include casinos, housing clusters, schools and other public buildings, day care centers, gymnasiums, and shopping areas. A septic system is considered a Large Capacity Septic System (LCSS) if it receives solely sanitary waste either from multiple dwellings, or from a non-residential establishment, where the system has the total capacity to serve 20 or more persons per day. LCSSs are regulated as Class V wells under the federal Underground Injection Control (UIC) Program. Although LCSSs can be individually permitted, the majority of LCSSs, are "authorized by rule" provided they meet minimum federal requirements. "Authorized by rule," means that an individual permit is not required.
EPA does not have permit requirements for septic systems used by single-family homes or non-residential septic systems receiving solely sanitary waste that serve fewer than 20 persons per day. However, if these systems are improperly sited, operated or maintained they can threaten water quality. EPA has the authority to address malfunctioning systems on a case-by-case basis.
The minimum federal requirements for LCSSs are:
- The owner or operator is required to submit basic inventory information to EPA or tribe with primary control
- The injectate cannot endanger an underground source of drinking water (USDW)
Inventory information includes: facility name and location, owner/operator name and address, nature and type of injection well, and operating status. A complete discussion is found on EPA's Minimum Federal Requirements for Class V Wells page of the UIC Program Web site.
The second minimum federal requirement prohibits injection that allows the movement of fluids containing any contaminants (such as nutrients, pathogens, solvents or heavy metals) into an USDW if the presence of that contaminant may cause a violation of any primary drinking water regulation or adversely affect public health.
If the LCSS is designed, operated, and maintained properly, they generally should not endanger USDWs. To get more information on LCSS in your area contact your regional UIC program representative (PDF) (23 pp, 145K, About PDF).
Some POTWs analyze wastewater samples and sludge at on-site laboratories. Laboratory procedures must comply with approved methods and meet NPDES monitoring requirements. Chemicals used in the laboratory include acids (e.g., sulfuric, hydrochloric, nitric), bases (e.g., sodium hydroxide, potassium hydroxide, sodium azide solution), and others (e.g., chlorine, ferric salts, carbon disulfide, benzene). The quantity of wastes generated depends on the number and types of tests performed. The storage and disposal of some wastes generated from laboratory activities may be regulated under the hazardous waste provisions of RCRA.
POTWs are responsible for operating the wastewater laboratory safely. To prevent laboratory accidents, chemicals should be stored in a properly ventilated and well-lit room. All bottles and reagents should be clearly labeled and dated. Volatile liquids that can escape as a gas, such as ether, must be kept away from heat sources, sunlight, and electrical switches. Cylinders of gas being stored should also be capped and secured to prevent rolling or tipping.
Under the pretreatment regulations (40 CFR 403), POTWs are required to develop and implement local pretreatment programs. Through this program, the POTW is directly responsible for the regulation of certain industrial users discharging to the wastewater treatment system. Information on pretreatment programs can be found at the Pretreatment Program section on the EPA's NPDES Web site.
Biosolids Management and Disposal
Some tribal governments are responsible for managing and disposing of sewage sludge (i.e., biosolids). Biosolids are a primary organic solid product produced by wastewater treatment processes that can be beneficially recycled (the fact that biosolids can be recycled does not preclude their disposal). These tribal governments must follow the federal sludge management program (40 CFR Part 503), which establishes requirements for the final use or disposal of biosolids when biosolids are:
- Applied to land to condition the soil or fertilize crops or other vegetation grown in the soil
- Placed on a surface disposal site for final disposal
- Fired in a biosolids incinerator
A fourth disposal option is landfilling. If biosolids are placed in a municipal solid waste landfill, the landfill owner/operator is responsible for ensuring that the biosolids meet the provisions of 40 CFR Part 258.
Chemical Storage/Hazardous Materials Management
If storing or using specified amounts of certain hazardous chemicals, a tribal government may be subject to planning and reporting requirements of EPCRA and Section 112(r) of the CAA. Hazardous chemicals may be used in various wastewater collection and treatment operations, such as disinfection as part of the treatment process, or cleaning and other maintenance activities. Specifically, chlorine and sulfur dioxide are commonly used in the disinfection (chlorination/dechlorination) process. Additional chemicals may be used in laboratory procedures to analyze wastewater samples. Facilities must generally submit hazardous chemical inventory and emergency release information as provided in RCRA, CAA, and EPCRA. Chemical emergency preparedness and risk management and prevention planning are key elements to understand.
Some tribal governments have enacted stormwater discharge programs. Stormwater discharges are generated by runoff from land and impervious areas such as paved streets, parking lots, and building rooftops during rainfall and snow events. These discharges often contain pollutants in quantities that could adversely affect water quality. Many industrial/commercial stormwater discharges are considered point sources and require an NPDES permit. The primary method to control stormwater discharges is through the use of best management practices.
Polluted stormwater runoff is a leading cause of impairment to water bodies. Over land or via storm sewer systems, polluted runoff is discharged, often untreated, directly into local water bodies. When left uncontrolled, this water pollution can result in the destruction of fish, wildlife, and aquatic life habitat; a loss in aesthetic value; and threats to public health due to contaminated food, drinking water supplies, and recreational waterways.
Under the CWA, the NPDES Stormwater Program is a comprehensive two-phased national program for addressing the non-agricultural sources of stormwater discharges, which adversely affect the quality of our nation's waters. The program uses the NPDES permitting mechanism to require the implementation of controls designed to prevent harmful pollutants from being washed by stormwater runoff into local water bodies.
The NPDES stormwater program requires operators of construction sites one acre or larger (including smaller sites that are part of a larger common plan of development) to obtain authorization to discharge stormwater under an NPDES construction stormwater permit. Tribal governments must apply if they meet either of the two parts of the stormwater regulation definitions of "operator."
Other Operations that may be Regulated
In addition, POTWs may be regulated for pesticide management. POTWs may use pesticides, particularly herbicides, to control weed growth and maintain the plant site. Activities related to pesticide use and storage may be regulated under the provisions of FIFRA, EPCRA, or Section 112(r) of the CAA.
Pollution Prevention in Wastewater Management
A substantial amount of the pollution generated by wastewater management activities can be prevented. In preventing pollution, wastewater treatment plants can serve as role models for their residential, commercial, and industrial customers; they can also help or require dischargers to reduce their own toxic discharges to sewers through education, on site assistance, and regulatory programs.
Typical Wastes Generated
Sewer line and wastewater treatment operations and maintenance are key to ensuring proper treatment of wastewater and protection of the environment. Unintended releases of partially treated or untreated sewage can result from leaks from pipes or sewers and inadvertent discharges to waterways.
The wastewater treatment process involves treating both the liquid and solid factions of wastewater. In doing so, various chemicals may be added to either the solids or the liquids to produce an appropriate product meeting discharge requirements. By products of the treatment process can include flared methane, bar screen waste, and grit chamber material.
Other Pollution Prevention Opportunities in Wastewater Management
Keep harmful chemicals out of the sewer lines and protect line workers, the plant, and the public's investment. Work closely with pollution prevention programs, economic development commissions, and pretreatment programs.
- Institutionalize a preventive maintenance program to predict problems before they occur instead of reacting to them after their occurrence
- Design, implement, and evaluate sewage acceptance procedures, including provisions for spill prevention, discharge limitations, hauler performance guarantee, and enforcement or permit revocation
- Explore, evaluate and implement alternatives to existing wastewater treatment processes, such as ultraviolet radiation or osmosis, to avoid using toxic chemicals such as chlorine and sodium hypochlorite
- Reuse or recycle solids (e.g., primary scum) and secondary screenings in areas such as landscaping. Check tribal regulations for any special requirements for disposal in Indian country and state and local regulations for any special requirements for disposal outside of Indian country
- Post and track statistical control tools to inform all employees of the plants target operating level and the actual operating level
- Establish a screening mechanism for procuring chemicals that evaluates non-toxic alternatives and reduces chemical dependence, thereby lowering hazardous waste use and avoiding hazardous waste generator status
- Be innovative in use and reuse of energy, such as fuel cells operating from methane, participating in the United States Department of Energy's (DOE) Building Technologies Program, including using heating/air conditioning controls and room sensors in buildings
- Use alternative transportation, such as bicycles, at the facility. Offer transit subsidies, telework, and flex-schedules for employees
For related information visit EPA’s National Indian Country Enforcement and Compliance Assurance Priority site and EPA’s Enforcement and Compliance Assurance Program in Indian country site.