Dealing with Off-site Runoff

I remember the first big storm that occurred after we moved into our current home: a river carved its way under the fence and through the newly sodded backyard. Where did it come from? A peek over the fence showed me something I hadn't noticed before. The adjacent backyard was a concrete slab, funnelling runoff from the house, outbuildings, and pavement through our yard. Granted, it wasn't my neighbor's fault. The problem had been there for decades and they inherited it just like us.

A number of people have similar experiences, though, when neighbors add on or developers substitute McMansions for bungalows. New guidance being developed by the City should address some of those infill issues, but what can you do about "run-on" short of legal action? In this case we looked at redirecting the river and decreasing its energy. And the application may give you ideas about how to handle your own off-site problem.

First, we talked with our neighbors about what we were observing. They made some changes to their yard, including switching two parking spaces to loose gravel. Tremendous! And it looks great too.

On our side of the fence, we used recycled concrete, which came from tearing out our own paved yard, to provide energy dissipation for the flow entering from the fenceline. Basically, that means putting something in the way of the stream to smack it around and is provided by the larger stone in the middle of the garden to the left. We then used the same materials to edge a planting bed along the fence and provided spaces between the concrete to allow water flow. The water then enters a horizontal gravel filter, made up of river rock, which dissipates the flow further and allows it to pass through the yard without being seen. The filter also acts as a walkway from the house to the play yard. On the downstream side of the walkway, I added a raingarden that is a few inches lower than the gravel bed.

Overall, the system dissipates the energy of the water entering the yard, filters the water, conveys it, and provides some infiltration. Afterwards, water exits into the alley. During high rainfall events, water flows through this system as well as overflows to the yard and a shallow lined channel directly to the alley.

I mentioned the design to someone recently and they asked "Isn't that just a walkway?" And I thought, "Yes, and No." I'll highlight again that stormwater controls don't have to look different, they just have to work different. And if it is mistaken for a walkway, great. That tells me its a job well done.

What's Up With Rats?

It seems each time I talk about raingardens, someone has to ask about vermin. You know, squirrels without the cute fuzzy tails: rats and mice. The question is usually, "Do raingardens bring in vermin?". My standard answer is, "No". But after hearing it so many times, I decided to get some additional advice on the topic.

I talked with both a horticulturist and a biologist about this question. On my list were Jay Ross, Horticulture Curator at the Tulsa Zoo, and Stephanie Rainwater, a biologist at URS. Jay and Stephanie both noted that any garden with dense vegetation can provide a nesting area for all types of critters, from songbirds to cats to, you know. The key to what critters you attract is what food supply is nearby. If you have insects, you should get birds that eat insects, and so on.

In the public arena, a community might consider whether the garden is located near areas of animal feeding (advised or not), such as a duck pond or petting zoo. Likewise the residential homeowner should consider whether they leave dog, cat, or bird food where other animals can access it. In my own yard, I've found the compost heap to be a problem.

But are there features that make raingardens uniquely less prone to being used by vermin than other landscaping? The answer is yes. Raingardens are designed to flood - every time it rains. There aren't a lot of critters that will put up with being flooded on a regular basis - they'll pick somewhere else to nest.

So, what does all this mean? Raingardens should be less likely to house these unwanted guests than other types of gardens and landscaping, a fact that should encourage others to bring stormwater controls into their landscaping.

Rainwater Harvesting: How Much is Enough?

This week's poll has to do with what people want to use rainwater collection for, whether it be watering lawns or running the commode. Even ambitious LIDers won't be using rainwater to wash clothes anytime soon b/c they don't have dual plumbing systems (potable/non-potable) in their homes. So that leaves most us looking at outside uses, watering the lawn and the like.

Rain barrels are becoming more and more popular. But it seems the minute most people put one in they want it bigger: a 55-gallon barrel doesn't go very far. How far you might ask? Well, I use a 55-gallon barrel for air conditioner condensate collection and am able to water my container plants for about week from one barrel. How much water do you need?

A traditional lawn needs about 1-inch of water per week during the summer. That's 0.623 gallons per week per square foot. (Sometimes I just call it a half-gallon per foot to make it easy.) If you have a lawn that is 20' x 50', that's 1,000 square feet of lawn. It would take 623 gallons of water per week. During the summer, let's say that it doesn't rain for a month. Over those four weeks your lawn would need 4 x 623 gallons = 2,480 gallons. If your lawn is bigger, you'll need more, maybe much more!

So, here's where reason kicks in. Are you ready for a 2,500 gallon (or larger) tank? Do you have the space? (A 2,500 gallon-tank is about 8 feet in diameter and 7 feet tall.) Does your neighborhood allow these kinds of appurtenances?

There are a number of factors to consider when evaluating "How Much is Enough?". Maybe for you it is a rain barrel to refill the fish pond, maybe it's finding out if the old cistern in the backyard still holds water, or maybe its having a system engineered for your specific needs. Whatever you decide, there's an opportunity every time the rain falls.