US lawIllinoisRegulationsTitle 35 — ENVIRONMENTAL PROTECTIONCHAPTER I: POLLUTION CONTROL BOARDSUBCHAPTER d: UNDERGROUND INJECTION CONTROL AND UNDERGROUND STORAGE TANK PROGRAMSPart 731 — UNDERGROUND STORAGE TANKSSubpart G731.17335 Ill. Adm. Code 731.173Previously Closed Systems (Repealed)Last amended: 1992Year: 2026Length: 8 wordsOfficial source Section 731 Section 731.173 Previously Closed Systems (Repealed)Previous35 Ill. Adm. Code 731.172Next35 Ill. Adm. Code 731.174