Modeling Straight Pipe Prevalence in Rural Alabama

EPA Grant Number: SV840024
Title: Modeling Straight Pipe Prevalence in Rural Alabama
Investigators: Elliott, Mark
Current Investigators: Elliott, Mark , Cohen, Sagy , Greer, Ashton
Institution: The University of Alabama
Current Institution: The University of Alabama , Oregon Institute of Technology
EPA Project Officer: Aja, Hayley
Phase: II
Project Period: July 1, 2020 through June 30, 2022
Project Amount: $75,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2020) Recipients Lists
Research Category: P3 Awards


About 75% of the US population has access to municipal systems with public sewers for wastewater treatment. The remaining 25%, more than 80 million people, are responsible for treating their own wastewater onsite; most of these use a conventional septic system. Septic systems require infiltration of wastewater into the subsurface, enabling wastewater treatment through filtration and natural degradation processes. However, there are some soil and geological conditions that preclude the use of conventional septic systems because it is impossible for the wastewater to infiltrate. In cases where the soil or geology are unsuitable for conventional septic systems, expensive alternative systems are typically employed. When lack of access to sewer coincides with unsuitable soil conditions and poverty, rural residents are left with no affordable options to treat their wastewater. In large parts of central Alabama, soils are characterized by impermeable clay and a shallow impermeable chalk layer. In these conditions, many residents are left without an affordable, safe and legal option for wastewater management.

The PI first became aware of this issue after arriving in Alabama six years ago and he has since dedicated much of his research activity to characterizing the scope and potential impacts of the problem in Alabama. There had been many reports of so-called “straight pipes” discharging untreated wastewater onto the ground, but no quantification of the scope of the problem in the counties with the worst soil quality. Dr. Elliott and colleagues recently found that a majority of unsewered homes of Wilcox County discharge untreated wastewater onto the ground based on inspections of over 10% of these homes (Elliott et al., 2017). Based on the population and typical daily wastewater production and pathogen concentrations in untreated wastewater, conservative estimates indicate that hundreds of thousands of gallons per day of raw sewage are discharged onto the ground in Wilcox County alone, resulting in tens of millions of infectious pathogens discharged into the environment. Not surprisingly given these statistics, there is also troubling evidence of adverse health impacts. A 1992 survey of soil-transmitted helminthiasis in Alabama revealed that up to 33% of children under-10 tested positive for one or more helminths (Badham, 1993) and in 2017, a journal article (McKenna et al., 2017) and popular press coverage (Pilkington, 2017) reported that hookworm was detected in nearly one-third of adults in a small sample of residents without proper wastewater management.

The potential for substantial health and environmental impacts is clear. However, there have been no substantive efforts to quantify the occurrence of illicit wastewater discharges in the Black Belt counties of Alabama. The inability to quantify the scope and impacts of straight pipes and the corresponding costs and benefits of various remedies has been a major barrier to a remedy for the problem. The anecdotal stories and media coverage are often dismissed as isolated incidents, but our experience and the troubling evidence of substantial health problems in poor communities with inadequate wastewater management indicate that these problems are common and widespread in rural Alabama. Therefore, there is an urgent need to characterize the locations, scope and impacts of straight pipes in rural Alabama to enable wastewater projects to be prioritized and for their costs and benefits to be estimated. This project will generate a tool that can defensibly quantify the extent of the straight pipe problem throughout the Black Belt, allowing community and countyscale wastewater management plans to be developed and the health and environmental benefits accurately assessed.


Phase II research activities, described in more detail below, will focus on the following tasks that build on the success of Phase I: 

(1) Researchers will work through longtime collaborators to increase the robustness of our model validation by engaging with at least ten local experts.

(2) Researchers will collaborate on creating a streamlined method or tool to validate and assess the model's output. The main objective of this activity is to allow for rapid iteration and refinement of the model. The resulting protocol or tool would make it easier and faster to expand the model into new geographic areas and adjust it to account for new variables.

(3) Researchers will expand the tested and validated model to all rural counties in the Black Belt of Alabama that have problems with shrink-swell clay preventing operation of conventional septic systems.

(4) The research team will disseminate findings to the general public, students, wastewater stakeholders and out colleagues in the Consortium.

(5) The research team will continue to work with the Consortium to transfer research findings into actionable information for legislators. Leveraging existing partnerships and data from this research effort to facilitate government agencies to invest in solutions for these problems. Given the pace of these developments and the interest at federal and state agencies it is realistic, even likely, that outreach activities will lead to implemented solutions during the Phase II project period.

Publications and Presentations:

Publications have been submitted on this project: View all 8 publications for this project

Supplemental Keywords:

Onsite wastewater, OWTS, Septic tanks, POTW, non-point source, NPS, rural poverty, neglected tropical diseases, environmental justice

Relevant Websites:

UA Team to Examine Untreated Sewage Issue Exit
With new grant, UA team mapping wastewater woes in Black Belt Exit

Progress and Final Reports:

  • 2021 Progress Report

  • P3 Phase I:

    Modeling Straight Pipe Prevalence in Rural Alabama  | Final Report