Hey all... new to the site.
I live in North Central Iowa on an aprx. 5 acres of land.
I am planning a small pond 1/4 - 1/2 acre.
The plan is to have the pond 10ft deep at it's deepest.

While Iowa is relatively flat (at least where we live) we live in a slightly elevated area. There is about 1/2 mile of slight elevation (corn/bean field) to the north of us but then to the east and west and south a slight drop in elevation. I've had two people out to give estimates. We plan on mostly filling the pond with a geothermal pump and dump (6 gallons per minute).

The guy today says there is about 2 ft drop from the back (north) side of the planned pond to the front (south) side of the pond. His cost for pond installation is $305 per hour (two heavy machines) which would take about a week to create the pond. He talks about removing the top soil, digging a 10ft trench all the way around the proposed area, filling it with clay, packing it down and then digging the pond, lining it with clay. He says he ALWAYS builds the pond with this 'double' layer of clay (one lining the pond and one in the 10ft trench which 'encircles' the pond). The pond would end up with an elevated dike/ridge around it (especialy toward the south/east/west). Total cost around $15,000 (basic pond construction).
The other guy says he would come in remove the topsoil, dig the pond, line it with clay. This pond also would end up with an elevated dike/ridge around it. His cost is $160 an hour (one large machine) and says it would take a 4-5 days or a total cost of around $6000 (basic pond construction).
Questions:
1) Is the 'double' clay lined construction necessary or over kill?
2) Will the pump and dump keep the pond full? I plan of course a spillway to make sure it is not too full. Both contractors think the pond will stay full if "you can get it full" -- neither one is too familiar with a 'pump and dump' system and how that works with filling or keeping a pond full.
3) I don't want too much 'seepage' because I don't want water in the basement... is this a problem. Our soil is called Franklin soil... with plenty of clay under the top soil. What methods are for reducing seepage or evaporation?
4) Other than creating the dike/ridge with the clay or hauling it away (NOT CHEAP) what can you do with it. I'd sorta like to keep the dike/ridge as low as possible so we can see the pond from lawn/fire ring/road/etc. {It will be seen from the house}
Thanks!!