Implementation of Swales at Ithaca College
by Chris Gordon, Lauren Krug, and Jenny Moore
For our final project we decided to construct a series of swales at the Organic Garden on campus. We chose the Organic Garden because they have been experiencing problems when it comes to water on their site. The garden is located at the bottom of a slight hill and water from campus runs down that hill and collects in the garden, making it very wet most of the time.
To help with their problem, we planned and constructed two swales above the garden. A swale is a type of earthworks that is a slight depression that runs with the contour of the land and is level along its length. They can be deep or shallow, or even under gravel and turned into a path. Another reason we chose swales is that they are a great alternative landscaping method that reduces runoff by capturing water in the berm and storing it. In other words, swales slow, spread, and sink water.
Another goal of our project was to foster sustainable behavior and do a public presentation of our work. The behavior we wanted to promote was capturing run-off water in the ground for use instead of the typical practice of getting water off-site as soon as possible, to keep it from eroding the landscape and pooling. Our target audience for this behavior was the Ithaca College Organic Garden Club and the Ithaca College Grounds Crew.
With any behavior promotion there will be barriers encountered, both physical and metaphorical. One of our challenges was to convey to the grounds crew that building a swale to get water off-site was a better alternative than the sometimes easier method of just digging a diversion ditch. Another barrier was public outreach. We made a work day through the Organic Garden Club, but it was difficult to find a time where everyone could come learn and participate. Therefore our turnout for the workday was minimal.
To build a swale, one needs to start at the top of their watershed, where the water begins it’s journey down the landscape and assess where the best place would be to build a swale. Once you’ve decided on the place, it is important to measure the contour lines of the area you have chosen. We did this using a water level. Then you begin to dig the swales, making sure they are staggered to allow for overflow. It is always best to make them bigger rather than smaller. The top of the berm needs to be level and compacted, but the basin does not need to be compacted but does need to be level. We made one end of our bottom swale slightly off contour to allow the water to flow off-site.
The formulas we used in calculating the measurements of our swale were as follows:
Area = 1/2 x Width x Depth
Volume of water – holding capacity = Area x Length
Volume = 1/2 x Width x Length x Depth
The calculations for our swale were: Water Holding Capacity= 3675 in3 = 306.25 ft3
We then planted winter rye seeds on the berm of each swale so that when they grow their roots will anchor the berm together and prevent erosion as well as store water even further in the berm.
The results for our swales were that they were effective for the most part. The night after our workday it heavily rained which filled the basins with water. The swales held the water in place except for one part that got slightly washed out which we repaired.
Our plans for the future include ensuring the basins are level so water drains properly from the site and possibly building two more swales above the existing two. We also plan to monitor and maintain the swales which would involve more encouragement of participation from the Organic Garden.
A big thanks to Karryn, the IC Organic Garden, IC Grounds Crew, and Brad Lancaster (author of “Rainwater Harvesting”).