Overview of Sewage Issues
Population growth in the Catawba-Wateree basin has created sewage disposal challenges. While most people in the basin used to rely on septic systems, increasing population density and poor soil conditions, make septic systems problematic. Many developers install package treatment plants to handle waste from development where septic systems are not viable, but these unmanned package treatment plants generally have a poor compliance record. Nobody wants a massive public sewage treatment plant in their back yard, but they are often needed to deal with the growing quantity of waste.
The rapid population growth in the Catawba basin during the past 40 years has created an ever-growing flow of human and industrial waste that the needs to be treated. When the population of the basin was relatively small, the Catawba River had enough natural areas to absorb, dilute and naturally treat waste discharges but the increases in population have strained the ability of natural systems to cope with the sewage. Municipal sewage systems have not been able to keep pace with the population growth in the region. Although the Catawba basin is one of the most populated basins in North Carolina and although the soils of the Catawba basin are often not conducive to septic systems, the Catawba basin has the highest density of septic systems in North Carolina. Many of these septic systems are discharging inadequately treated wastes in adjoining streams, rivers and lakes. In order to facilitate high density development in areas not serviced by public sewer utilities, many developers are installing unmanned packaged treatment plants, which historically have a poor record of compliance.
Where do sewers overflow near you? Click here to see a map of sewer overflows since 2014.
Methods of dealing with sewage - Basic explanation of the different methods of treating sewage.
- Septic systems - Septic systems are the most common method of sewage treatment in the Catawba basin. Septic systems treat waste in an anaerobic bacterial environment which develops in the septic tank and (when operating properly) decomposes the waste discharged into the tank before the waste is discharged into the soil through a drain field. Septic tanks can be coupled with other on-site wastewater treatment units such as biofilters or aerobic systems involving artificial forced aeration, but this is not typical. Most septic systems serve a single residence. Periodic preventive maintenance is required to remove the irreducible solids which settle and gradually fill the tank, reducing its efficiency. In rural areas, a properly maintained system can provide a safe method for treating sewage for decades. However, septic tanks can be problematic in densely populated areas and in the clay soils common in the Catawba basin.
- Packaged treatment plants - A package plant or packaged treatment plant is a pre-engineered and pre-fabricated method of treating wastewater through an aerobic treatment process. Typically, the plants are automated and an operator is not present to continually monitor operations. Packaged treatment plants are common in the sections of the Catawba basin where municipal sewer systems have not kept pace with the growth in the area. Package plants are commonly installed in suburban residential neighborhoods and commercial developments where public sewer utilities are not available and the developer does not want to use valuable land for septic systems or other non-discharge methods of treatment. When designed and operated properly, the final effluent may be discharged into streams, rivers or lakes. However, due to the frequent absence of human operators, these facilities sometimes discharge improperly treated waste for days before the problem is discovered.
- Publicly operated treatment works (POTWs) or municipal wastewater treatment plants - POTWs are typically owned by local government agencies, and are usually designed to treat domestic sewage and pre-treated industrial wastewater. Like package plants, POTWs in the Catawba basin typically treat wastewater through an aerobic treatment process and discharge the treated wastewater into a stream, river or lake. Unlike package plants, POTWs typically have human operators continually monitoring the proper functioning of the system and larger facilities in the Catawba basin typically employ advanced treatment technologies to minimize pollutants. POTWs typically have large sewage collection systems that are used to get sewage from homes and businesses to the sewage treatement plant. These collection systems often employ miles of sewer pipes and hundreds of pumps that parallel streams and rivers. When the pipes or pumps fail, the result is often a discharge of untreated sewage to a surface water.