Welcome to the forum!

You also will need some silt pillows or maybe a few of those seepage dumpsters.

If you only have a foot of muck on the bottom of the pond, and the pond is 100'x40', you can easily calculate the amount of muck that you will take out, if you can get the water drained out of it pretty quickly. 1' of muck on the bottom of the pond equals about 148 cubic yards of muck, depending on how much water is mixed with it.

www.hoosierpondpros.com

[Linked Image from lh6.ggpht.com]
http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).