The commission shall determine the fair market value for television station leases based upon independent appraisals and existing leases for television stations shall be extended at said fair market rental for at least one period of not more than twenty years: PROVIDED, That the rates in said leases shall be renegotiated at five year intervals: PROVIDED FURTHER, That said stations shall permit the attachment of antennae of publicly operated broadcast and microwave stations where electronically practical to combine the towers: PROVIDED FURTHER, That notwithstanding any term to the contrary in any lease, this section shall not preclude the commission from prescribing new and reasonable lease terms relating to the modification, placement, or design of facilities operated by or for a station, and any extension of a lease granted under this section shall be subject to this proviso: PROVIDED FURTHER, That notwithstanding any other provision of law the director in his or her discretion may waive any requirement that any environmental impact statement or environmental assessment be submitted as to any lease negotiated and signed between January 1, 1974, and December 31, 1974.