Who is the company?
Start with what they are offering per acre (pond and pipeline) and then consider other uses of the land (crops, pasture rental, etc) to get a fair value. Having the pond and pipeline may mean less truck traffic to the site (which would not get you any more cash - it would just tear up the road and be more noise). Be sure to have everything spelling out in writing - will the pond be lined, how long will it be there, will site be restored to original condition, payment for any timber loss, additional taxes/fees caused by the pond, will it be fenced, they have to prove liability insurance and protect you from responsibility of the pond. Maybe even consider have some soil recording done - proving you have 12" of topsoil now, and that you have 12" when they restore - filling the hole and spreading a little of the original topsoil is not the same as restoring to original condition. Make your list of "priorities/demands" and talk to them. Remember the pond can be located somewhere else and water piped in to the site, so you don't have them over a barrel.