GreenDwellingSeattle

In our ongoing Seattle Green Building series following the construction of Columbia City Green we are going to spend the next few posts outdoors talking about the rainwater harvesting, landscaping, and the gardens.  We will show how the treatment and preservation of the site that these homes are built upon is an important part of any building project; green or otherwise.

Our urban areas are literally covered with what is known as Hardscaping.  Streets, sidewalks, patios, parking lots, etc.  This hardscaping disrupts the earth’s natural ability to manage rainfall and instead places a huge burden on storm water systems occasionally resulting in urban flooding and a host of other issues.  Green builders have taken a hard look at different ways to reduce the amount of water we send to storm water systems and are utilizing the benefits of approaches such as green roofs, rainwater harvesting, and rain gardens in order to achieve this goal.  In an ideal scenario we would be able to keep all the water that lands on the property within its boundaries, giving the planet an opportunity to filter contaminants from the rain and reducing those that are typically pumped out into our lakes and coastal areas.

800 Gallon Cistern

In a previous post we have spoken about the extensive Green Roof systems that they have installed at Columbia City Green.  These green roofs are going to work in conjunction with Rainwater Harvesting which will be achieved by the installation of two 30 gallon rain barrels and one 800 gallon underground cistern which has been outfitted with a pump for each home.  Case has estimated that the annual rain catchment they will realize is just over 6,000 gallons per year that will come from approximately 850 square feet of roof area.  The rain that is collected in these containers will be used for irrigation of the drought tolerant landscaping and urban gardens they will be installing at the project.

Seattle is famous for the amount of rain that falls here each year, but is 44^th on the list of the cities in the US receiving the greatest amounts of precipitation.  Further more, the majority of the rain that falls in Seattle occurs between the months of November and March which means that approximately 64% of the annual rainfall they collect will occur during these months.  This translates to about 3,840 gallons of harvested rain for each home at Columbia City Green during the winter months.  For this reason both the cistern and the rain barrels have overflow pipes that will be connected to the rain garden located in between the two homes.  They have sized the system to support approximately 3 months worth of irrigation needs.   A drip irrigation system will be installed for the vegetable garden, significantly reducing the amount of water that is needed to supply fresh vegetables all summer long.  We will talk more about the rain garden they have planned shortly so stay tuned.

The metropolitan Seattle receives its water supply from the snowpack that our Cascade mountain range receives annually.  The Seattle Times recently reported that climate change is the likely culprit for cutting the snowpack in Washington’s Cascade Range by at least 20% according to Joseph Casola, a University of Washington doctoral student in atmospheric sciences.  So you see Rainwater Harvesting overcomes a number of challenges of urban development; stormwater management and reducing the demand on a dwindling snowpack, and the wasting of potable water for non-potable purposes.  It will also help to lessen the impact on our delicate marine ecosystems.

One particularly interesting detail about Rainwater Harvesting is that many state governments actually own the rights to the precipitation that falls on rooftops and structures within a given state!  In the case of Seattle our local utility has received a water right permit from the Washington State Department of Ecology, clearing the way for homeowners to harvest rain water without the risk of legal challenge.  You may want to check with your local utility before investing in a rain barrel or cistern for your home.

If this is the first post you have read in our Seattle Green Building series, take some time to go back through prior posts.  The links in the preceding paragraph will easily get you there.  If you have questions or comments about any of the posts please share them.  These homes will be listed for sale mid-June.