You need to contact an eminent domain lawyer in Texas with experience representing landowners in these kinds of negotiations or suits.
If they pay once, it's because they are buying the right to use the easement area - and to limit the use of the land above - forever. The price for that should reflect and fairly compensate you for the lost use and rights. The price should be based on a fair appraisal of the land.
You need advice on the rights and procedures for this in Texas. It may be that the pipeline company will have to pay for your attorney's fees and experts if they try to go through eminent domain -- but the way that works varies from state to state. I'm not a Texas attorney, so the only and best advice I can give you is to find a good Texas attorney who knows the ins and outs.
The 5th Amendment of the US Constitution concludes with the phrase "....nor shall private property be taken for public use, without just compensation."
As a land owner, you have federal constitutional fundamental rights that are implicated in this situation. When government (Federal, State or local) wants to take or use private property for a public purpose, this is referred to as the government's power of eminent domain. The government authorities may ultimately be able to make use of your private property, but may not do so without "just compensation." The question in these types of cases becomes how is "just compensation" determined.
In addition, Texas state law may also afford you additional rights in this situation.
Seek the advice of a Texas attorney to help you navigate this situation and make sure you receive "just compensation." In Florida, the government pays for attorneys fees in eminent domain actions. Most states are the same. But contact a Texas attorney to find out what the law is in TX on this issue.
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