swale / gum tree query

Gday im doing a design for someone, dont have heaps of experience with swales, just wondering if I can build a swale through the path of where a gum tree is to be chopped down, also does stump grinding remove the entire root mass of a gum tree to make this possible to work. Most of the gum trees in query are 30-40cm thick and about 10-15metres tall.
Am concerned about leakage of swales from remnant gum roots. Soil is hard clay pan soil of victoria
Any feedback much appreciated.

http://www.oasisdesign.net/index.htm

http://www.harvestingrainwater.com/

Try reading from the two sites above. Both have sections about swales and berms. Good luck.

I'm in central Victoria, black claypan country. You'll be fine, but keep your swales filled over spring and summerto reduce cracking. Or, push seeds into the cracks like I have.

i think you want the swale to leak into the clay layer
i like to pollard the gums to give the other things a go

Hey thanks for your help, sorry for such a late reply to this. Never checked again. cheers dudes.