Final Report: Straight Pipe and Septic Impacts on Rural StreamsEPA Grant Number: SU836775
Title: Straight Pipe and Septic Impacts on Rural Streams
Investigators: Elliott, Mark
Institution: University of Alabama
EPA Project Officer: Page, Angela
Project Period: September 1, 2016 through August 31, 2017
Project Amount: $14,994
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2016) RFA Text | Recipients Lists
Research Category: Sustainability , P3 Awards , P3 Challenge Area - Water
About 75% of the U.S. 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 four 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 the unsewered homes of Wilcox County discharge untreated wastewater onto the ground, based on inspections of more than 10% of these homes (unpublished data). 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 also is troubling evidence of adverse health impacts. Although now over two decades old, the most recent survey of soil-transmitted helminthiasis in Alabama revealed that up to 33% of children under the age of 10 years tested positive for one or more helminths (Badham, 1993).
There is an urgent need to characterize the scope and impacts of the onsite wastewater problem in rural Alabama. Additionally, for state agencies, water managers, and other non-researcher stakeholders, a major factor preventing unambiguous detection of human fecal contamination in water samples is the lack of feasible and affordable methods with adequate specificity. The lack of such specificity causes citizen groups to erroneously fixate on point sources of pollution, enables polluters to deflect criticism, and frustrates environmental agencies caught between the two parties. Developing a feasible remedy for this situation is of utmost importance. We propose that the U.S. EPA approach to Illicit Discharge Detection and Elimination (IDDE) for stormwater in urban areas may hold promise.
Phase I activities primarily involved the following major tasks: (1) site identification and drainage feature map development; (2) multiple-indicator water sampling, principal component analysis (PCA), and preliminary conclusions; and (3) outreach and raising awareness with numerous stakeholders. Site identification and flow-routing were carried out for potential sample sites in ArcGIS; it allowed us to identify accessible sampling points down-gradient of areas with a high concentration of known straight pipes with corresponding upstream controls. An example flow-routing map is included in the full final report. Multiple-indicator water sampling included a wide range of biological, geochemical, and fluorescence parameters.
The goal of this task was to identify a signature associated with fecal contamination that would enable a small number of relatively simple and inexpensive tests to confidently identify human fecal contamination in these rural streams. Outreach and raising awareness was primarily accomplished through two conference presentations and an EPA webinar. The goal was to make local, state, national, and international stakeholders aware of the problem, hopefully enabling a coalition to seek funding and solutions.
Progress was delayed by a major drought from late-August until it finally stormed in late-November, 2016. Over 70 consecutive days with no measureable rain (longest on record in Alabama) forced us to abandon many sites that we had established earlier in 2016.
Following loss of our initial sampling sites, ArcGIS flow-routing was used to identify promising new sites for water sampling. We were able to identify Newbern, a town with a concentration of straight pipe discharges. It also allowed us to identify Big Prairie Creek, a robust perennial creek with accessible sampling points that could be used to monitor contamination upstream, adjacent, and downstream of Newbern.
We have identified promising analytes through principal component analysis (PCA). Preliminary analysis indicates that coupling E. coli, optical brighteners (present in both detergent and toilet paper), chloride, dissolved organic carbon, and ammonium-N and soluble reactive phosphorus (SRP) show potential to successfully identify most samples that are heavily contaminated with untreated wastewater in our sites around Newbern. We are continuing to work to refine the list of parameters to the simplest and most affordable. Generalizability to other sites, further selecting the most effective indices, and lower wastewater concentration thresholds will be addressed in Phase II as described below.
Our PCA indicates that Big Prairie Creek, which receives no legal wastewater discharges, consisted of nearly 7% untreated wastewater downstream of Newbern. E. coli concentrations in Big Prairie Creek post-drought were recorded at over 100,000 per 100 mL, indicating that the PCA results are reasonable (raw sewage has average E. coli concentrations roughly 1,000,000 per 100 mL).
While it is unrealistic to expect quantifiable benefits to health and the environment less than 1 year into a small research project, we have made remarkable progress since the project began in fall 2016.
Our presentations have drawn attention to the problem. In particular, the EPA Decentralized Wastewater webinar presented by Dr. Elliott on March 28, 2017 (see Publications and Presentations) led to substantial interest at EPA Region 4 and Headquarters. In April 2017, we began discussions with EPA on potential ways to leverage funding (through three specific USDA and EPA mechanisms) to pilot wastewater treatment solutions in the region; partners at EPA currently are exploring the options.
The ultimate goal of this effort is not just to study the problem, or enable others to study the problem using our tool, but to enable action and funding for solutions that protect public health and the environment. We plan to continue working with EPA and state agencies, and leveraging existing partnerships and data from this research effort to improve awareness of the problem and facilitate government agencies to invest in solutions.