Decentralized Concept – An organizational concept of wastewater management that urges treating wastewater, then reusing and/or dispersing the reclaimed water, as close to where it is generated as practical in each circumstance, to produce wastewater systems that are more fiscally reasonable, more societally responsible, and more environmentally benign than those produced by conventional strategy. This concept minimizes investment in a conveyance infrastructure that does nothing but move pollution from place to place, eliminates much or all of the cost of operating and maintaining that conveyance infrastructure, and minimizes the public health and environmental liabilities inherent in that conveyance system. As this concept entails multiple treatment centers distributed throughout the service area, it urges the use of treatment methods such as sand filters (or similar biofiltration concepts) and constructed wetlands which are inherently stable and incur low operational and maintenance liabilities. This concept also urges use of effluent sewer technology for any conveyance that is needed, as this minimizes investment in, disruption by and maintenance liabilities of the conveyance system. Production of treated effluent at these distributed treatment centers can drastically reduce the cost of implementing beneficial reuse projects, as it may minimize the extent of redistribution infrastructure. A decentralized concept system may include: on-site systems contained entirely within the fee simple boundaries of the lot it serves; small-scale collective systems, with their reuse/dispersal sites on easements on the lots served, on vacant lots purchased for this purpose, on off-site properties, or a combination of these; larger scale collective systems utilizing dispersed or aggregated reuse/dispersal sites or discharging to surface water. Any or all of these may be employed within the service area of a single management entity to compose a unified wastewater management system. Further, these concepts may be combined with conventional methods to create a unified system serving the full range of land uses, from low-density residential to urban core. Management of the system would be planned to assure appropriate levels of oversight to each of the system components, as applicable to each situation. The level of collectivization in any given circumstance would be due to such factors as development density, topography, type(s) of development, opportunities for reuse, and availability of appropriate dispersal sites or discharge routes.
The papers in the menu below provide fuller explanations of the concept and its benefits relative to “business as usual” in the “waste” water management field.
When I permitted the Lowman Ranch project in 1985, I was constantly asked why I didn't just propose a package plant like a “normal” engineer. So in 1986 I wrote a paper laying out the philosophical and technical background and justifications for organizing wastewater systems in concert with what I termed the “decentralized concept” of wastewater management. That original paper included dissertations on technologies and examples which are now dated. This version focuses solely on a general explanation of the concept, which in many situations will produce a wastewater management system that is more fiscally reasonable, more societally responsible, and more environmentally benign than conventional practice.
In an effort to offer a vision of where the decentralized concept could take society, I wrote this piece in 1996. I dispensed with any consideration of how we transition to that state and simply presented a view of what a reused-focused decentralized concept system would look like when fully implemented 20 years in the future. The vision is presented as a day in the life of a wastewater system inspector.
This piece was written in 2001, in response to a request to offer a comparison of centralized and decentralized wastewater systems with the pros and cons of each. It offers a more expansive overview of the concept and its advantages over conventional practice.
Many colonias in South Texas are located in areas where extending existing sewerage systems or installing new conventional, centralized systems is very costly. The decentralized concept is key to providing affordable wastewater service to these developments. This paper discusses the practical application of the decentralized concept in this real-world setting, offering a more concrete understanding of how the concept might be applied in a variety of situations. It also offers discussions of the technologies favored for use in the decentralized concept.
A truncated version of a document I produced for the Bluff Service Area (BSA) as part of the facility planning process for a wastewater system to serve Bluff, Utah, written as the proceedings paper for a presentation at the 2008 NOWRA annual conference, this paper reviews the decentralized concept strategies that were considered. These included: (1) a combination of cluster systems and individual on-lot systems, all managed by the BSA; (2) several small “cluster” systems distributed around the town; (3) two larger “cluster” systems, one on each side of the major wash that bisects the town. The BSA chose to implement the large-scale option, with the effluent dispersed in subsurface drip irrigation fields. These fields will be sited, as much as practical, to maximize the beneficial reuse of the reclaimed water for irrigation. The collection, treatment and dispersal system strategies are also reviewed, as well as issues particular to circumstances in Bluff.
Two articles that review the case for considering a decentralized concept strategy in Wimberley, Texas, and provides a general review and justification for that strategy.