LIMITATIONS, IMPLICATIONS, AND SOLUTIONS FOR WASTEWATER DISPOSAL IN ALABAMA’S BLACK BELT

The Alabama Black Belt is a region of low population density, high poverty, and high incidence of pathogen-related illness. Centralized sewer systems serve a low percentage of the population in a few cities and towns in the region, with onsite septic systems utilized by most residents in rural areas. The use of these systems is limited by poor soils developed from the Mooreville Chalk. Vertisols derived from weathering of the formation consist of shrink-swell clay, clay loam, and silty clay loam classified as Group III to IV soils due to frequent flooding and very low permeability (average saturated hydraulic conductivity around 0.21 ft/d). Depth to the water table ranges from 6 inches to greater than 80 feet. Septic systems rely on infiltration of wastewater into the subsurface for final pathogen removal, therefore these soils limit the use of conventional onsite disposal methods. An expensive engineered onsite treatment system is the only legal alternative for most residents; therefore, many poor households have resorted to the use of “straight pipe” disposal systems that discharge untreated wastewater directly to the surface, resulting in diminished water quality with high pathogen content. Wastewater discharge to surface waters requires riparian access as well as a NPDES permit, which is unrealistic for most households or household clusters. Possible solutions include expanding existing conventional sewer, advanced onsite treatment systems, and decentralized clustered systems (that use septic tanks to collect solids and convey the liquids to a common treatment unit through small PVC pipes). Although all three strategies have their place, decentralized clustered systems have the most potential to affordably address water quality and health issues for the greatest number of residents. However, widespread application of these technologies is limited by economic conditions throughout the region and will require state and/or federal funding to reach scale. In addition, the problems caused by this issue and the attendant policy implications highlight the need to consider wastewater in any future State water resource plans. These issues in Alabama’s Black Belt signal the need to integrate societal and scientific elements into sustainable wastewater disposal.