If the municipalities jointly contracting under this article shall, at any time after the execution of such joint contract, deem it expedient to lease a portion of the lands of the Passaic valley sewerage commissioners for the purpose of constructing on or in such leased lands pipe lines and sewage storage tanks with appurtenances, such municipalities and the Passaic valley sewerage commissioners may enter into a contract or contracts for such purposes, upon such terms and for such consideration and period of years as may be agreed upon between the contracting parties. Said municipalities may enter into a contract or contracts with said Passaic valley sewerage commissioners for the disposal of sludge by barge to sea or otherwise.