I thought pointReturn required about 6 swales spaced 120′ apart on the west to east slope. Each swale would average about 400 feet in length. Hand digging would be too slow, even if there was enough labour or volunteers available; and they were not. The ubiquitous back hoe, popularly known as the JCB, is too clunky to patiently carve out contours. One of the spin-offs of digging swales is aesthetic. When you have picked out a contour line and created a swale on it, it’s shape and appearance will spontaneously harmonise with the landscape. You will have landscaped the property in a way no professional designer can have conceived. It is therefore good to dig a swale slowly and with care, pile the earth on the downward side with care and eventually plant it with care.
I surprised myself by deciding to fairly bust my wallet and buy a mini excavator. [The new attitude to money had obviously taken hold.] I could operate this myself and patiently sculpt out swales over months. When I am done with them, there would be other jobs I can use the machine for. I have written elsewhere of the logic that went into my decision to buy the machine.
As the banks of the swale would eventually be planted out fairly thickly, I decided that the swale bottom should be wide enough to let the excavator to traverse it, during the summer months when its without water. I will have access to desilt the swale or scoop out leaf litter for use as mulch elsewhere. I might even grow a crop on the swale floor until it’s shaded out.
Size and number of swales depend on rainfall patterns. If it rained almost daily, you probably need no swales at all. In a forum post on the subject, a contributor Paul Cereghino has summed up the sizing issue succinctly: “distance between swales decreases as slope and rainfall rate increases and ability of soil/swale system to absorb water decreases.” If like around pointReturn, the entire annual rainfall of 900mm came down a week each, six months apart, more swales need to dug. I picked on a width of 7′ and depth of 2′, as a good size for motorable access. Since swales are absorption and not storage bodies, they would be empty most of the year. There would be ramps at either ends and the excavator or a tractor can traverse it.
The Yanmar VIO20 arrived to much local adulation. It was everything I had hoped for and a joy to operate. Using an A-frame, I marked out the first contour line to the west of the main pond and got to work. I dug a swale all right but the operator’s inexperience showed: the swale had to be hand dressed by members of the A-Team. “We are cleaning up after you,” they might have justifiably muttered under their breath.