How to Build Swales (Part 2 Earthworks)
Swales are simply ditches on contour. The purpose of a swale is to hold water and accumulate nutrients to feed your berm. In time this will help to rehydrate land.
Swales can be any size, but obviously the larger the ditch the more water you can hold. I decided on a 16 inch deep ditch, 2 foot wide.
1. Make sure you do the proper prep-work. Get your underground utilities marked, mark your contour lines, design your swales, and arrange for labor and equipment if needed.
2. Decide on the size of your swales. Keep in mind the size of your digging equipment.
3. Dig your swales on contour, starting from the top of your slope, working your way down. Place the excavated soil on the downslope side of your ditch making a berm.
4. Level the base of your ditch with hand tools if needed. Rake your berms level, but do not compact.
5. Install level spillways in the berms so overflow will not erode your berms. A spillway every 20-50 feet should be sufficient.
6. Add organic material to your ditches. This will help to feed the trees and shrubs you plant on the berms. I used a rough wood mulch. My neighbor used branches covered with leaves.
7. Seed your berms with something that grows quickly to help prevent erosion. I used an annual rye seed. I will seed the berms with a mixture of clover, lambsquarters, and alfalfa in the spring.
8. Plant trees, shrubs, and groundcovers in the berms. This will occur in the early spring.
The swale project went pretty much as planned. It took me three days to dig about 2000 linear feet of ditch with the mini-excavator I rented. It took me another day and a half to move all the mulch into the trenches. I hired (3) temporary laborers for the week to do the hand work. They each worked about 35 hours. I worked about 45 hours on the job.