You can look up the cost share through EQIP online.  I just picked a random county in Michigan here.    It’s going to be called a waste facility closure and probably pay based on the cubic feet of lagoon volume, subject to some volume adjustments for freeboard and such.  https://www.nrcs.usda.gov/getting-assistance/payment-schedules


Sounds like you want to fill the lagoon back in.  Is it dug into a hillside with a dam/embankment or is dug out on the flat with the spoil around the edges or was the excavated dirt long spread out or hauled away?  In other words, where is the fill coming from to fill it back in?  Look at the practice scenarios here, probably 67 or 68 for examples with sample hypothetical budgets depending if fill is onsite or offsite . https://www.nrcs.usda.gov/getting-assistance/payment-schedules


In the end you will have to haul out the water and dig out the solids down to the original clay.  You had to decide if you want to haul more water/agitation, or just get rid of the water off the top and start digging out the solids directly.  Either way you will have to spread both liquid/slurry and the solids/sludge.  You will probably have to get a slurry and sludge test and prove you are applying to agronomic recommendations based on some soil test and yield.  Sounds like a great job for this past dry winter or a summer wheat field.  If you don’t have a shallow enough slope you can probably just dig a ramp into the lagoon for hauling since it is going away afterwards.

Then there will be an assessment of how much, if any, of the clay liner you have to haul off or if you can just bury it, based on whatever NRCS or the state of MI have decreed.

Then you basically fill the hole up, either with fill you have onsite (embankment or whatever) or fill you bring in.  Grade it so the water runs off, probably make it green on top with the approved grass or wildflowers or whatever.

So you will need a pump, slurry wagon, loader, solid spreader, and a dozer or pan, at a minimum.