I've spent a couple of days laying out swales in what will be my pig pasture. I used a home built A frame level and marked with survey flags. My first question is When you make the cut for the swale do you mound the dirt along the flags or do you make your cut along the line of flags and pile the dirt below the flags. Second question is how closely do you have to follow the flagged line? I have several areas where there is a substantial difference between two flags. Thanks.
Well both would probably work. It would be hard to mark the contour line where the mound and ditch meet while also working around the flags. I think most of us usually dig everything below the flags so that the flags don't get buried and you have room to work on the downslope/whole swale. Swales don't have to be all that precise unless you're making the mound super minimal or tiny. You should have plenty of time and observation to tweek it unless you live in a climate that might have super hard rain the first time they are tested....even then it shouldn't be too hard to fix where it overflows. Just get it as good as you can and make sure to watch/observe it when it rains or right after. You could even watch it fill up (if you feel safe enough) while it rains and adjust it if it seems to not work right as it fills. I'm sure there are a bunch of swales threads in the forum if you search also. Hope it works out!
Let me tell you my experience with our hogs and swales.
Make your swales for hogs (or pigs) wide and shallow, otherwise they will destroy the berm as they travel over it or they will root into the berm and destroy it.
I tried a "normal" type swale and ended up making it three times wider and 1/3 as deep, this worked far better as the hogs traveled back and forth over the berm and they negotiated the swale a lot better too.
I usually lay mine out and leave the flags on the uphill side of the swale, with the berm in the normal positon.
I try to keep the same distance between flags so I don't get "off line".
In the hog area I pack the berms and seed them as I go, most times this gets something growing on the berm faster for me.
Thanks for the good ideas. Walter Jeffries had another good idea. He runs his pig pastures parallel to the Swales and fences the Swales off creating a no grazing zone along the swale. The Swales and vegetation don't get damaged.
That is also a great idea, as is using the immediate down slope from the back of the berm for a row of fruittrees within the swale fence line, that way the hogs can't damage the trees and any fruit fall becomes treats for the hogs.