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Design, Assessment, and Management of Onsite Wastewater Treatment Systems: Addressing the Challenges of Climate Change
Department of Plant and Soil Sciences
Onsite wastewater treatment systems (OWTS) serve approximately 25 percent of the United States population. In rural and unsewered watersheds, they are the only means to treat wastewater. As federal subsidies for funding centralized municipal treatment have ended, new development in rural areas is almost exclusively dependant upon OWTS. New challenges necessitate advances in our understanding, design and management of OWTS that warrant a multi-state effort of Land Grant scientists.
Of particular note are three drivers of change:
1) Recognition that OWTS are no longer a temporary, 'stop gap' approach that will be replaced by municipal sewers. OWTS are increasingly in use for decades and are used for all types of rural establishments - raising concerns for long-term hydraulic and treatment performance.
2) Increasing demands by public and environmental health professionals that OWTS achieve high and reliable levels of nitrogen, phosphorus, emerging chemicals and pathogen removal rates - well beyond those associated with conventional technologies.
3) Challenges presented by the possible decadal changes in climate, such as rising water tables or severe drought, argue for new approaches to site selection, design and water reuse.
As with any technical field, the science must continually evolve to produce site suitability predictive tools, technologies and management policies that meet changing societal needs and are responsive to climate change and national water requirements, while protecting public health and the environment
In addition, policies must address the challenges that result from implementation of the new solutions. While, conventional OWTS appear deceptively simple, consisting of a solids storage tank and a soil absorption field for effluent. The vast variability in climate, soils, hydrology, use and environmental sensitivity of rural America requires the application of soil physics, soil microbiology, soil chemistry, pedology, hydrology and engineering to site, design and manage systems that will protect human and environmental health and still encourage rural development.
Beyond science and technology, advances in operation, maintenance, and management of OWTS at the watershed, county and state level are an essential component in maintaining the functionality of these systems. Thus, a multi-disciplinary effort is required to assure treatment capability and build greater confidence at all user levels.
The outcome of this work will contribute to the many aspects of rural life that are linked to OWTS including economic viability and environmental and human health. The enormous variation in soils, geology, climate and hydrology that affect the proper function of onsite wastewater treatment systems across the nation requires multi-regional collaboration to ensure standardization of state-of-the-science and engineering approaches to assessment and protocols. This will afford considerable momentum to the creation of a successful AES multi-regional model.
2011 Project Description
The enormous variation in soils, geology, climate and hydrology that affect the proper function of onsite wastewater treatment systems across the nation requires multi-regional collaboration to ensure standardization of state-of-the-science and engineering approaches to assessment and protocols. Kentucky's diverse regional geology and soils require intensive on-site investigations to assess site suitability for best treatment approaches.
During 2011, 33 Health Department Environmentalists participated in class and field training workshops to improve their soil morphology evaluation skills and establish more efficient site assessment and system performance protocols. The training included sites in the Bluegrass and Mountain regions of Kentucky where fragipan and shallow to bedrock soils pose severe limitations in the installation, operation, and management of septic systems. A series of diverse soils were evaluated in the above regions and the performance of the installed wastewater treatment systems was monitored on a regular basis.
In addition, several alternate systems were evaluated on sites not conducive to conventional treatment system installation.
The Soil Site Evaluation training provided to Health Department Professionals continues to improve their skills in more objectively and efficiently assessing soil suitability ratings and selecting the best treatment system possible for each site. Furthermore, it provides the opportunity to monitor the short and long-term performance of the installed systems and compare treatment efficiencies.
The data base developed from these studies will be an invaluable source of information for improving our state and regional waste water treatment guidelines and drastically reducing ground water contamination risks.