|Wastewater treatment systems are one of the US’s most widely-used pollution control technologies in the US. These systems’ treatment process includes sewers collecting wastewater, transporting the water to treatment plants, completing a cleaning process, and finally discharging the wastewater.
Municipal wastewater treatment plants, also referred to as publicly owned treatment works (POTWs), filter physical, chemical, and biological pollutants from the wastewater received from households, businesses, and industries. Differing from municipal wastewater treatment facilities, about 50% of homes in North Carolina use on-site wastewater systems, or septic systems (EPA, 2017). They generally have a tank, a distribution box, and subsurface absorption lines with perforated pipes laid in a gravel bed. On-site wastewater systems provide an alternative, natural way to treat and dispose of domestic waste without being connected to a centralized municipal sewage treatment system.
Major water quality concerns associated with untreated or poorly treated wastewater entering water systems include high levels of dangerous bacteria, hazardous materials, elevated total suspended solids, pharmaceuticals, and excess nutrients. Population centers contribute greatly to the amount of daily loads entering bodies of water from POTWs. Inflow and Infiltration (I & I) is a severe water quality implication resulting in the pollution of estuarine waters by raw wastewater. Inflow occurs during storm events when stormwater surges into and overwhelms a sewage collection and treatment system. Infiltration is the process of groundwater entering a sewer pipe system through uncapped sewer line cleanouts, gutters connected to lateral sewer lines, inadequate sewer manhole covers, and cross connections of stormwater lines with sanitary sewer lines (Deaton, et al., 2021). Sewer pipes also receive infiltrated groundwater through faulty pipe joints, sewer pipe cracks, broken manholes, and collapsed lateral pipes.
Coastal North Carolina faces more challenges with wastewater treatment systems failing due to sea level rise, more frequent and severe king tides, higher rainfall amounts, and seasonal temperature effects on groundwater levels (Allen, 2019).
Pump stations and wastewater treatment plants (WWTPs) are built to receive specific peak flow volumes and rates which can be exceeded with the increased flow from I & I. With a higher risk of overflow, there is also an elevated risk of untreated waters being released from a WWTP. Additionally, communities, especially those home to low-income citizens, often do not have adequate financial resources to maintain and update wastewater infrastructure. Lowincome counties face challenges with a lack of federal funding and the expenses of infrastructure upkeep and replacement, contributing to a greater risk of sanitary sewer overflows (Deaton, et al., 2021).
Sanitary sewer overflows (SSOs) and the resulting water pollution, are generally the effects of failed wastewater infrastructure. During an SSO, the spill may consist of hundreds to millions of gallons of sewage overflow that contain dangerous pollutants (Deaton, et al., 2021). The implications of these malfunctions on water quality include algal blooms resulting from nutrient loading, increased bacteria and toxin levels, fish kills, and contaminated sediments. In addition to the depletion of available oxygen, algal blooms can lead to the release of hydrogen sulphide and ammonia, both potentially toxic to aquatic life in low concentrations. (Shahidul, 2004).
The NC DEQ, Division of Water Resources, just announced the launch of a new GIS reporting application aiming to increase awareness of recently reported SSOs.
As a result of water quality advocates, DWR developed an online mapping tool to help better identify where these SSOs were occurring, volume spilled, and proximity to recreational waters. The app highlights the most recent spills which have occurred in the last 7 days through a graduated blue dot based on estimated volume, as well as continue to collect and add data on a rolling calendar basis.
CLICK HERE TO ACCESS THE SSO DATA.
Waterkeepers from across the State of North Carolina have been advocating for this for several years, after several spills and sewer overflows happened in their watersheds.
Hartwell Carson, French Broad Riverkeeper, works with CCRW White Oak Waterkeeper, notified the coalition group of the new system last week. Hartwell mention that the group “realized the current public notice was widely outdated, as it only provides a press release several days after the spill. This potentially leaves people recreating in polluted waters.”
MountainTrue, CCRW, and several other Waterkeeper groups across the state, advocated for change to the reporting system. These changes help to modernize access to the information to the public. The Division of Water Resources did the heavy lifting of making it happen within the Department and we are grateful that DEQ has taken this step forward. We are hopeful that other reporting methods will have similar updates forthcoming. We also hope this will be a good tool for the public to make informed decisions that further push the reduction of sewer overflows across the state.