At any time during the twenty-year term set forth in § 46-2A-20, or following its expiration, the board may delete the term limitation condition upon a finding that sufficient information has become available to determine:
At the end of the twenty-year limitation, the board may cancel a permit or amend the permit with a new term limitation of up to twenty years, if the board is unable to make a finding after notice and hearing that sufficient information is available to delete the term limitation. The priority date for any permit issued with a term limitation or amended with an additional term limitation shall be the date the original application was filed.
SDCL 46-2A-21