How to clear an area for a campus community garden?

My university wants to start a community garden. We have secured roughly 1 acre of land that previously has been unused and is mostly covered by snow at the moment, some willow and grass. One suggestion was made to remove the snow then burn it, disk it and spray it with a pesticide to get rid of the grass and clear the area for our garden plots. Now I really don't want to do that, what are some other ways of getting the land ready for gardening that are more in line with permaculture/organic practices?

Part of the problem is that we want to get the garden ready for sowing by June and don't have a lot of man-power at moment, so hand-pulling grass may not be feasible. We do however, have access to pigs and chickens and I would love to incorporate them into the process.

Any advice is greatly appreciated!

If you want to plant it by June then your best bet might be to sheet mulch. Cover it all up with a lot of dead biomass, top it with some compost and then plant into it. As long as you keep the grass covered, it'll die off and contribute nutrient to the soil.

There is NO NEED to kill it all off with herbicide and pesticide. Let nature do it's thing.