Grantee Research Project Results
Final Report: Modeling Straight Pipe Prevalence in Rural Alabama
EPA Grant Number: SU839462Title: Modeling Straight Pipe Prevalence in Rural Alabama
Investigators: Elliott, Mark , Weber, Joseph , Cohen, Sagy , Blackwell, Aaron , Greenberg, Rebecca , Munasinghe, Dinuke , Gentrup, Jessica , Sokolenko, Ana , Humburg, Jamison
Institution: The University of Alabama
EPA Project Officer:
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: Heavy Metal Contamination of Soil/Water , P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources , Urban Air Toxics
Objective:
The overall objective of this project was to generate the first mathematical model to predict the presence of “straight pipes” (household discharges of untreated wastewater to the surface) using publicly available secondary data (e.g., soil data, property parcel data).
Background: 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 used 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 enables legislators and local stakeholders to prioritize wastewater projects and justify spending based on clearly defined risks and benefits.
The innovative aspects of this project included: (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 project incorporated 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 the methods that we have developed 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 worked with the student team members to integrate the model into the spring 2019 undergraduate course CE 420: Environmental Measurements. Senior environmental engineering students learned about the problem, the modeling approach and its applications and policy relevance. Our team also presented our results at local, regional and national conferences and seminars to raise awareness of these issues and affect change.
Summary/Accomplishments (Outputs/Outcomes):
Phase I activities to date have primarily focused on: (a) building a preliminary GIS based model to predict the prevalence of straight pipes in rural communities, (b) growing partnerships at the state level through formation of the Consortium for Alabama Rural Water and Wastewater, and (c) outreach and dissemination of preliminary outputs to increase awareness of the general public with help from the Office of Strategic Communications at the University of Alabama and subsequent press coverage. These activities are discussed in order below and are ongoing through the end of Phase I in October. Further details of these activities are provided below.
Building the GIS model: The preliminary GIS model has been built and applied it in two Alabama counties, Wilcox County and Hale County. See Figure 1 for mathematical model. Wilcox County model outputs are illustrated in Figure 2; see the body of the report for more model outputs. The model relies on a suite of geological and socioeconomic data. Data on saturated soil hydraulic conductivity and the soil depth to a confining layer was obtained from the USDA’s Soils Survey Geographic Database (SSURGO). Data on parcel and building values were purchased from local government contractors at the county level. Population data and road networks were made available by the US Census Bureau. Finally, elevation data was acquired from the USGS.
The soil parameters were used as factors that contribute to septic system failures. The parcel value data acts as a high resolution estimate of income and an estimate of poverty levels in the area. The rest of the data obtained from the USGS and Census Bureau is not used directly in the model but is used in improving the readability of the maps or in additional analysis of impacts on people living in the area. The mathematical model itself is as follows:
Figure 1: Preliminary GIS model
The original model output an inverse risk rating because all of our major variables are actually inversely related to the risk of straight pipes. The Pval is the value of a parcel in US dollars normalized by the area of the parcel, A, in acres. The area is adjusted by a log function to reduce its impact as not all of a parcel’s value comes from acreage. It is also converted to decimeters in the model to prevent the log function from returning a negative value. The depth to a soil confining layer in centimeters is represented by the variable D and is normalized by the maximum depth measured by the soil survey, two meters. Finally, Ksat is the saturated soil hydraulic conductivity in micrometers per second.
The model is executed within the ArcMap software using the raster calculator tool to directly perform the model math on each pixel of the map. All of the data comes in the form of polygon data, so the first step of the process is converting each set of polygon data to a raster dataset useable by the model. The area of each parcel can be derived using ArcMap’s geometry calculator if the original dataset lacks that component. ArcMap’s model builder function was used to streamline the process and ensure consistency as well as making the model more accessible to potential end users.
Figure 2: Phase I model output for straight pipe risk in Wilcox County, Alabama.
Growing partnerships: Dr. Elliott has developed numerous partnerships with many stakeholders including state agencies, current and retired state employees, federal congressional offices, the Alabama Governor’s office, members of the press, many university faculty, and community organizations. These activities have substantially raised the profile of this issue in Alabama. The most important of these partnership activities has been the formation in early 2019 of the “Consortium for Rural Alabama Water and Wastewater.” It was organized primarily by Dr. Elliott and his colleagues at the University of South Alabama, Prof. Kevin White and the Vice President for Research Dr. Lynne Chronister. Prof. White is acting as the first Coordinator of the Consortium.
The Universities and federal and state organizations and offices listed below (“Members” of the Consortium) have agreed to coordinate efforts to resolve the issues associated with drinking water quality and the lack of adequate water/wastewater treatment, disposal, management, and access in rural Alabama. The Member organizations are: Alabama Department of Public Health (ADPH); Alabama Department of Environmental Management (ADEM); Auburn University; University of Alabama, Tuscaloosa (UA); University of Alabama, Birmingham; University of South Alabama; University of West Alabama; USDA-Rural Development (Alabama Office); Lixil Americas; Governor’s Office, State of Alabama; Senator Doug Jones Office; and Congresswoman Terri Sewell’s Office. This cooperation and coordination is critical because establishing water/wastewater management protocols and defining appropriate sanitation needs in the Black Belt is complicated. Solutions will require detailed planning, innovative technologies, regulatory modifications, economic considerations, traditional and alternative financing options, testing of options, social considerations, education and training of operators/citizens, and the involvement of multiple partners.
Outreach and dissemination: Outreach and dissemination of project findings during Phase I was far more successful than we hoped. Through our work with the UA Office of Strategic Communications, an April 2019 press release on this P3 Phase I project (Jones, 2019) led to phone conversations with Alabama journalists. These conversations resulted in extensive coverage of these issues on public radio (AP, 2019), in numerous Alabama newspapers (e.g., Brown, 2019), an article disseminated widely by the Associated Press (AP, 2019), extensive online coverage (e.g., Pillion, 2019; Walker, 2019) and thousands of shares on social media.
Conclusions:
While it is unrealistic to expect quantifiable benefits to health and the environment less than one year into a small research project, we made remarkable progress in Phase I, particularly with respect to the media attention that the project has received. Citizens of Alabama are far more aware of the dire state of rural wastewater than they were prior to the start of our project. And partnerships have advanced substantially, including the establishment of robust relationships with state and federal partners.
The ultimate goal of this effort is not just to study the problem, or allow others to study the problem using our tool, but to enable action and funding for solutions that protect public health and the environment. One of the major barriers to a remedy of the straight pipe problem in rural Alabama has been the inability to quantify the scope and impacts of straight pipes and the corresponding costs and benefits of various remedies. This project yielded substantial progress toward the broad availability of a tool that can defensibly quantify the extent of the straight pipe problem throughout the Black Belt, allowing community-scale and county-scale wastewater management plans to be developed and the health and environmental benefits accurately assessed.
We continue to work with our partners in the Consortium, our contacts in the media and other stakeholders and collaborators to improve estimates of the scope and impacts of straight pipe discharges in rural Alabama to increase awareness and facilitate investment in solutions.
References:
Associated Press (2019, Apr 15) “UA Team to Examine Untreated Sewage Issue.” Retrieved June 26, 2019. https://www.apr.org/post/ua-team-examine-untreated-sewage-issue
Brown, M. (2019, Apr. 26) With new grant, UA team mapping wastewater woes in Black Belt. Montgomery Advertiser. Retrieved June 26, 2019 from https://www.montgomeryadvertiser.com/story/news/2019/04/26/new-grant-ua-team-mapping-wastewater-woes-black-belt/3575964002/
Jones, A. (2019, Apr 9) “EPA Grant Assists in Understanding Wastewater Issues in Rural Alabama.” Retrieved 26 June 2019. https://www.ua.edu/news/2019/04/epa-grant-assists-in-understanding-wastewater-issues-in-rural-alabama/
Pillion, D. (2019, Apr 13) “How much untreated sewage gets dumped in Alabama’s Black Belt? UA team trying to find out.” AL.com. Retrieved 26 June 2019. https://www.al.com/news/2019/04/how-much-untreated-sewage-gets-dumped-in-alabamas-black-belt-ua-team-trying-to-find-out.html
Journal Articles:
No journal articles submitted with this report: View all 1 publications for this projectSupplemental Keywords:
Onsite wastewater, OWTS, Septic tanks, POTW, non-point source, NPS, rural poverty, neglected tropical diseases, environmental justiceP3 Phase II:
Modeling Straight Pipe Prevalence in Rural Alabama | 2021 Progress Report | 2022 Progress Report | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.