Tag Archives: GSI

Rainwater Catchment

Potential Unexpected Costs From GSI Mandate


A round metal grain silo in a grassy area surrounded by trees.The GSI mandate or “Green Stormwater Infrastructure” can create unexpected costs for new commercial and residential construction.Controlling stormwater through GSI compliance requires on-site infiltration and/or use.

Roof runoff, along with impervious surfaces,contributes tooverwhelmed stormwater systems, which may result in pollutants entering our waterways and wetlands. A design using both methods of rainwater collection and infiltration can be the most cost-effective, while being beneficial to the environment.

A serene garden pond surrounded by rocks and lush greenery.Directing roof runoff for irrigation, toilets, laundry, or even pre-infiltration potable water, will reduce costs frommunicipal water supplies. During the rainy season, collected water can supply these uses while overflow from the cistern can be directed to infiltration.Irrigation in the summer months being supplied by the desired amount allocated from storage will enable the rain garden or infiltration system to be sized for a smaller amount of runoff while supplementing city water usage.

Rainwater Catchment

Can Rainwater Collection Control Stormwater Issues in WA?


Water droplets resting on a green leaf with prominent veins.
Photo courtesy of danschenker.com
Is promotion ofrainwater collection an opportunity for counties in Washington State to control stormwater?

As of October 2009, rainwater collection is legal in all counties in Washington State. Many county Health Departments are allowing collected rainwater for potable use as well. King County, the largest county in the state, allows for potable usage. Seattle Public Utilities offers rebates for rain gardens in certain areas of Seattle such as Ballard. The Rainwise Program encourages home owners to collect and use roof runoff to help control storm water. Many consumers have taken advantage of this program and are practicing good storm water control. The GSI or “green storm water infrastructure“mandate addresses the issue of storm water runoff for new construction by total infiltration of impervious surfaces on site.

But what about all the existing buildings and houses throughout our state including Seattle area, wherestormwaterrunoff still overwhelms sewer systems, causing intentional sewage release into the Puget Sound during large rain events?

What can the counties and municipalities do to encourage existing building and home owners to control their runoff, thus reducing or eliminating these large releases? Public awareness is an excellent start. Countyand municipality funded educationusing media andpublicservice announcements promoting rainwater catchment practices while offering incentives such as theRainwise program would generate interest. A properly funded program of encouragement and incentives would create morepublicinterest to adopt rainwater collection, as it has with the Rainwise Program, while money being spent to promote would be absorbed by the cost savings totheoverwhelmed systems we experience now.

Rainfall collection and use can be part of thesolution to Seattle’s storm water issue, augmenting the GSI mandate by addressing runoff, not only from new construction, but from existing buildings and homes as well. It’s fair to saythat most Seattleites would welcome being part of the solution — if given the opportunity.

Rainwater Catchment, Residential Rainwater Collection

Rooftop Rainwater Harvesting is Simple and Cost-Effective


Brick building labeled Seattle Fire Station with surrounding plants.The report referenced below comes as the Environmental Protection Agency is in the process of updating its national standards for controlling runoff pollution from new development with regard to rainwater harvesting.

“As America’s expanding urban areas struggle with major water supply shortages and runoff pollution problems, capturing rainwater from rooftops provides a tremendous untapped opportunity to increase water supply and improve water quality” according to a recent analysis by the Natural Resource Defense Council (NRDC)

In the Seattle, area roof runoff is already mandated by the Federal Green Storm Water Infrastructure (GSI) for all new construction to disperse all impervious surface run off on site.

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