WHITHER THE WATER GOES - PT. 2

WHITHER THE WATER GOES - PT II

January 13, 2013: So back to the three things we have to do with stormwater: collect, convey and dispose.

Collecting precipitation hasn't changed much over the years. It falls on our roofs and is captured by gutters or it falls on the ground and the soil captures it. Unless your home is located inside the Tacoma Dome, that's still going to be the way most water is collected. Nothing is going to change much there. Let's look at what we can do to convey the water that's collected: 1) on the roof and 2) in the soil.

On the roof (and I'm assuming it's a roof with gutters), that water is going to be conveyed into downspouts. An alternative to ugly downspouts are rain chains. While traditional downspouts are a closed system, rain chains open the stormwater to the air so there may be some water splash and in very cold weather you can end up with an ice pillar. You also have to recollect the water at the bottom of the rain chain if you want to continue to convey it someplace. A single rain chain will accommodate about 30 linear feet of gutter. Rain chains are also more expensive than traditional gutter downspouts, but they never clog. My recommendation is to use rain chains where they will be seen and keep traditional gutters where they won't be seen.

When the water gets to the bottom of the downspout or rain chain we have to figure out what we're going to do about it. Do we want to reuse that water? Do we want to convey it somewhere else where it may be beneficial? Do we want to convey it somewhere else and just get rid of it?

Traditionally, that stormwater has been conveyed by underground pipes to the sewer system and thence to the sewage treatment plant. It's a terrible waste of good water and a big cost to taxpayers. Ah, how much friendlier to the environment and the next bond levy for a new sewer plant it would be to utilize that water on-site.

Reusing it means irrigating on demand. Rainwater harvesting it's called. In an earlier blog, I pontificated on the advantages and disadvantages of rainwater harvesting and I won't flog that blog again except to point out that in the Pacific Northwest we have ample rainwater resources, but not when we need them in summer (when we need to irrigate). That means storage. The more rainwater you need to irrigate, the larger the storage you need. A 55 gallon rain barrel at the end of a gutter might last a week or two during the summer for the average yard (not counting turf). We can also convey that rainwater to a more elaborate storage container such as an inground cistern tank or an aboveground one.

If we instead wish to convey that water to where it can do some future good, then there are a variety of methods we can use. One of the most popular these days is the rain garden. In the simplest terms, the rain garden is a depression that is constructed as a temporary storage of rainwater. The idea is for the water to be held and percolate into the soil and when planted it's providing an attractive semi-irrigated part of the landscape. The key to a functional rain garden is that it be sized for amount of water it will collect, designed and constructed to promote soil percolation, and planted with plants that can tolerate water extremes (remember we get rain in winter, not in summer). Proper selection and use of native plants that have adapted to just such a watering scheme is key. The rain garden is not the place to display your marigolds and petunias.

What about drainage solutions in the surrounding landscape. You first have to ask the question of where is the water coming from. Well rain, of course! But, is it just what falls on the ground or is there water directed from the roof or runoff from your neighbor's hillside? Identifying the sources will help choose the drainage solution.

For water to move on top on or in the soil, there has to be a slope (2% minimum). Sometimes we can contour the landscape surfaces to promote slope for drainage. That's often what's done around the foundation of your house to get water away from it. But when there is no slope in a landscape you have go underground to create a slope. This is done by trenching and installing drain tile, a generic term for flexible pipe with holes in it that water can seep into and flow down. The drain tile is sloped and it must lead ultimately to someplace where it is disposed. On flat ground that ends up being a big hole in the ground that either has a collection tank or is filled with drain rock, called a rock sump or, more erroneously, a French drain.

The most typical drainage problems I get called upon for is lawn drainage. The most frequent complaint being that lawn is so wet in the winter it can't be used for anything - the kids can't play on it, the dog comes in tracking mud all over the house, please make my lawn dry in the winter, or at least not a swamp. If ripping out the lawn, re-contouring the surface, and re-installing the lawn is not an option (and it is usually not due to expense and topography), then trenching and installing drain tile is the most feasible solution. These underground pipes are usually installed in a pattern that resembles a candleabra or herringbones. The tighter the soil, such as clay, the tighter the pattern. Drain tile installation is not cheap. It can run from $5-$11 a lineal foot. If the lawn has an irrigation system in it, it makes it an extra challenge(cost) to install drain tile. No matter what marvels I may be able to achieve with drain tile, I can't promise your lawn will be as dry a billiards table in the winter.

There is another alternative to solving drainage issues I haven't spoken about and that's what I call "re-purposing". That is accepting the way the world drains (or rather your yard) and finding another acceptable purpose for it. Perhaps that chronically wet area can be made into an aesthetically pleasing wetland, bog garden, or rain garden. Can a soggy area of the lawn be re-purposed to a shrub bed?

Wither the water goes. You can change it or find a way to live with it. That's something you, with the help of your local landscape professional can decide

F & P