Section 1H. Notwithstanding section 7 of chapter 44, a municipality or sewer district adopting section 1A may borrow and assess betterments for a term not to exceed 50 years or the useful life as approved by the department of environmental protection, whichever is shorter, for the construction its wastewater treatment systems and conveyances determined; and provided further that short term borrowing may extend for a period not to exceed 5 years.