April 9, 2006


Sewers harming valley watershed

Decentralizing waste systems could be critical to protecting resource, habitat

By Simon L. Gruber
For the Poughkeepsie Journal

A paradigm shift, already under way, is essential if we are to keep our wastes from spoiling water resources in the rapidly growing Hudson River watershed region. Moving away from central sewers is an important strategy for protecting our drinking water supply and the quality of our streams.

To think about a sustainable approach for wastewater and stormwater management, it's useful to first look backward.

For centuries, sewers were built for larger cities to protect public health and provide drainage by channeling raw sewage and stormwater into streams. As populations grew, the effects of pollution on rivers became apparent. The 20th century saw a massive investment in sewage treatment, with ever more stringent standards applied to stream discharges. Newer discharges to small streams now require costly advanced treatment to remove nutrients to avoid over-fertilizing nuisance weeds and algae that can deplete the dissolved oxygen fish need to survive.

Regulators and engineers have generally assumed the best solution, environmentally and economically, is to treat waste at a centralized plant and discharge the effluent to a stream. A similar paradigm has prevailed for stormwater drainage: move the water away as quickly as possible.

This approach is sometimes called the Big Pipe Paradigm. Even with treatment, pollutants are discharged to streams. And water pumped from the ground for drinking water is discharged directly to streams, depleting groundwater that would otherwise sustain stream flows during dry weather. Without this flow of groundwater, streams are likely to overheat, killing trout.

Plants are very expensive

Building and maintaining large pipe networks is very expensive, and can account for more than 60 percent of the total cost for a centralized system. But in an era when advanced treatment is required to remove nutrients, the original purpose for moving water long distances no longer applies.

At the same time, relying exclusively on septic systems requires large lot sizes and consumption of open space, and precludes clustering of houses. Soils only have so much capacity to treat waste without allowing contaminants to foul water supply wells.

Another school of thought favors a decentralized approach to managing wastewater. Instead of one large plant discharging to a stream, this approach uses a combination of individual septic systems and smaller community waste treatment systems. It allows homes to be built close to one another, but uses soil and plants to treat sewage, thereby avoiding discharges to streams at a fraction of the cost of centralized systems.

Decentralized systems can help to ensure a sustainable water supply because we can treat the water close to its source and use it to recharge groundwater. Farms, parks and forests can all be used for soil dispersal, so systems can be designed to fit, irrigate and fertilize the local landscape.

Together with clustering homes, preserving open spaces and other site-design tools, decentralized waste and stormwater strategies can help to protect stream corridors and adjacent habitat.

Stormwater can also be managed better. As open areas are developed using conventional designs, new impervious surfaces (buildings, roads and parking areas) prevent rainwater from infiltrating the ground. The volume of runoff to streams increases dramatically, leading to higher flows during storms but lower flows during dry weather. Stormwater and wastewater designs that emphasize soil infiltration help maintain natural stream flows.

In the long run, a fully sustainable approach to watershed planning can potentially integrate wastewater and stormwater management with agriculture, silviculture and other environmental and economic activities. For instance, most fertilizers used to grow the nation's food come from petroleum and other non-renewable sources. Re-capturing nutrients from wastewater could soon become a high priority for fostering growth of trees, shrubs and animal feed crops.

Sounds too good to be true? Well, there is one catch: decentralized systems, like most technologies, require proper design and ongoing management to work properly. With good reason, regulators are reluctant to approve smaller systems unless they will be managed effectively. Municipal leaders in some communities, recognizing that compact development, open space protection, and sustainable watershed management can be combined using these design concepts, are beginning to think about municipal management programs.

If this hurdle can be overcome, decentralized design concepts promise to become an integral part of land use planning and help to ensure sustainable watersheds for future generations.

Simon L. Gruber is the project manager of the Orange County Decentralized Wastewater Management Project.

Editor's note

Today's Our Environment features deal with a topic that was the focus of a recent forum, "Sustainable Water Resources Management: Working With Nature," hosted by the Hudson River Watershed Alliance at the Garrison Institute. The articles cover both the technical issues related to pollution from sewage treatment, and the moral and ethical imperative to act in the absence of governmental mandates. Next week, look here for tips on maintaining your septic system.

On the Web

Visit the Hudson River Watershed Alliance Web site: www.clearwater.org/sustainablewatershed for more information.

Copyright 2006, Poughkeepsie Journal. Reprinted with Permission.
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