N.J. Stat. Ann. § 40:14A-42

5. A sewerage authority shall not require that a maintenance guarantee required pursuant to section 3 of P.L.1999, c.11 (C.40:14A-40) be in cash or that more than 10% of a performance guarantee pursuant to that section be in cash. A developer may, however, provide at his option some or all of a maintenance guarantee in cash, or more than 10% of a performance guarantee in cash.