Modeling Straight Pipe Prevalence in Rural Alabama

EPA Grant Number: SU839462
Title: Modeling Straight Pipe Prevalence in Rural Alabama
Investigators: Elliott, Mark , Blackwell, Aaron , Sokolenko, Ana , Munasinghe, Dinuke , Humburg, Jamison , Gentrup, Jessica , Weber, Joseph , Greenberg, Rebecca , Cohen, Sagy
Current Investigators: Elliott, Mark , Cohen, Sagy , Weber, Joseph , Blackwell, Aaron , Greenberg, Rebecca , Munasinghe, Dinuke , Gentrup, Jessica , Humburg, Jamison , Sokolenko, Ana
Institution: University of Alabama - Tuscaloosa
Current Institution: University of Alabama
EPA Project Officer: Page, Angela
Phase: I
Project Period: November 1, 2018 through October 31, 2019
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2018) RFA Text |  Recipients Lists
Research Category: Mercury , P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources , Urban Air Toxics


More than 20% of US households, roughly 70 million people, live in homes not connected to a municipal sewer system and are responsible for treating their own wastewater onsite (EPA, 2017). Onsite treatment is accomplished primarily using conventional septic systems that rely on subsurface discharge. However, many areas of central Alabama have impermeable clay that causes conventional septic systems to fail. The rural poor in these areas have no feasible and legal wastewater treatment option and thus many households discharge raw sewage to the ground through so-called "straight pipes" that run from the home to a surface trench or to a wooded area.

Although technically illegal, site inspections in three Alabama counties indicate that straight pipes are common (Elliott, 2017). One detailed study of all unsewered homes in Bibb County, AL found 15% straight pipe (White and Jones, 2006) and a follow-up study in Wilcox County found 60% of unsewered homes used a straight pipe (Elliott, 2017). Based on these straight pipe figures, the ground and water bodies of just these two counties receive over 500,000 gallons of raw sewage each day. To put this into context, a one-time sewage spill of 5000 gallons will typically make the news and the local newspaper. These wastewater conditions in Alabama have attracted the attention of UN Special Rapporteurs on Human Rights to Water and Sanitation (UN, 2011) and Human Rights and Extreme Poverty in 2017 (UN, 2017). Additionally, recent articles in major media outlets, including Newsweek (Ballesteros, 2017) and The New York Times (Tavernise, 2016), have covered wastewater in Alabama, and The Guardian covered the discovery of hookworm among Alabamians with poor sanitation (Pilkington, 2017).


Despite the international attention and the troubling evidence of the return of tropical parasitic diseases thought eradicated in the US, no one knows how common these untreated wastewater discharges are in rural Alabama. We propose to use data gathered through past onsite inspections in three Alabama counties (along with USDA soil data, topography, property parcel data from county assessors, etc.) to build a model that provides the first ever estimate of the number and location of these household raw sewage discharges in rural Alabama. Modeling the scope and location of these raw wastewater discharges is essential and will enable legislators and local stakeholders to prioritize wastewater projects and justify spending based on clearly defined risks and benefits.The innovative aspects of this project include: (1) building the first model to quantify straight pipe discharges in the US, (2) integrating multidisciplinary data and expert knowledge in modeling local wastewater issues, and (3) generating maps estimating the magnitude of raw sewage discharge in rural watersheds. We propose that our GIS based computer model will be able to reliably predict regions most in need of support for rural wastewater.


The proposed project will incorporate people, prosperity and planet through research activities and community outreach. Many of the rural poor people in Alabama have been left behind and are subject to conditions unthinkable to most Americans today. Quantifying the scope of these wastewater issues is essential to motivate governments to protect their rural poor people. We hope that these methods will enable detection and prevention of onsite wastewater discharges. Pathogens in the environment lead to waterborne disease, impacting people and prosperity and exposure can be prevented through proper wastewater management. Preventing discharge of untreated sewage also protects the planet by reducing nutrient concentrations in ecosystems and waterways. Dr. Elliott plans to work with the student team members to integrate the model into the spring 2019 undergraduate course CE 420: Environmental Measurements. Senior environmental engineering students will learn how the model was built, how to use it, and its applications. Our team will also present our results at local, regional and national conferences and seminars to raise awareness of these issues and affect change.

Expected Results:

Phase I efforts will focus on building and validating the model using existing data. Written outputs will include the Phase I report to EPA and Phase II proposal, with journal publication to follow the completion of Phase I. While our long-term goals for this research include substantial water quality and health outcomes, measurable environmental changes are infeasible given the research focus and length of Phase I. However, outreach outcomes are planned for Phase I; we will present our project and future plans to local and state-level stakeholders. During a possible Phase II, we hope to work with water and health managers to iterate on our modeling tool, expand the geographic footprint and develop it into a web based application.

Contribution to Pollution Prevention and Control: Point source National Pollutant Discharge Elimination Systems (NPDES) permits for wastewater treatment plants have become increasingly restrictive. However, discharge of raw and inadequately treated onsite wastewater continues unabated in many areas. This proposal is directly relevant to nonpoint source pollution prevention and the Clean Water Act, in addition to environmental health and environmental justice for poor rural communities. This project attempts to create a tool for the prediction of onsite wastewater discharges in rural areas, enabling identification and prevention of such discharges.

Publications and Presentations:

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

Supplemental Keywords:

watersheds, non-point source pollution, viruses, bacteria, decision making, modeling, southeast, OWTS, septic tanks, rural poverty, neglected tropical diseases

Progress and Final Reports:

  • Final Report
  • P3 Phase II:

    Modeling Straight Pipe Prevalence in Rural Alabama