Chambers transforming decentralised treatment
The need for onsite wastewater treatment (WWT) in North America has been driven by high land prices and environmental regulation. Dennis F Hallahan, technical director of US WWT specialist Infiltrator Systems explains how innovations in the technology make it suitable for a wide range of applications.The onsite WWT industry in the US has evolved dramatically over the past 15 years, spurring the need for new approaches to decentralised applications. Along with tightening environmental regulations, rising urban land costs have challenged scientists, engineers, regulators and product manufacturers to develop new ways of managing wastewater.
The relative ease or difficulty of onsite development can be a function of the standards by which onsite wastewater systems are sized and constructed. If regulations can keep pace with scientific and technological developments, historical constraints on single-family home construction can be responsibly amended or reduced through adjustments to regulations.
Adjustments to regulations may include approving new treatment and disposal system technologies, for example, leachfield products, such as plastic leaching chambers, which provide a more efficient means of delivering wastewater to the subsurface.
Historically, regulations for conventional stone and pipe leachfields were based less on science and more on a trial-and-error process. Many regulators are now reviewing the available scientific research findings and third-party testing data and reexamining onsite policy accordingly.
With the regulatory shifts have come further innovations in onsite wastewater systems, providing a dramatic increase in the number of options available.
Installers are relying on advanced systems and technological innovations to maintain their business. Where repair work is an installer's mainstay, chamber systems and advanced treatment options can provide a means for upgrading a failing system by using reduced space and with minimal site impact.
It is increasingly difficult to find quality building lots for development, so engineers and designers are moving toward innovative, space-saving and flexible technologies that can be easily adapted to site conditions. For example, an articulating chamber product can be installed at a reduced size and contoured to match the available landscape.
Over the past 30 years, chambers have evolved dramatically in design and are now commonly used for onsite treatment in basic and advanced applications. The first chambers to be used commercially in the US were installed in New England in the early 1970s.
These concrete ameration chambers were more efficient than previous traditional stone and pipe systems. However, they were heavy and unwieldy to transport, and labour-intensive to install.
The rapid advancement of plastics technology made plastic the next logical step in the evolution in chamber design and plastic chambers were introduced in 1987. It is estimated that one-in-four wastewater treatment systems constructed in the US today is a chamber system.
While the principals of treatment remain the same, plastic chambers offer tremendous benefits over their concrete predecessors and even greater benefits when compared with the older methods of installations that involved stone and pipe trenches. In addition to the traditional use in septic system leaching trenches and beds, chambers have been used in sand filters, mound systems, ET beds, community (cluster) systems, constructed wetlands, large-scale wastewater treatment plants, with pretreatment devices, and even on toxic waste remediation sites.
New chamber designs offer even more flexibility in system design and installation and provide enhanced onsite wastewater system treatment. In actuality, plastic chambers are going through their fourth generation of evolution with the most current design one that offers maximum flexibility in installation, while retaining the highest levels of infiltration possible.
Manufacturers have listened to their customers and the feedback over many years from contractors, regulators and designers. Improvements now allow the chamber to articulate at each joint, they are easier to handle, install and transport, and are less prone to soil intrusion.
In the future we will see many new system designs and advanced treatment options developed in response to changing environmental and economic needs. Chambers will be at the forefront of innovative solutions to the world's wastewater problems.