1. (a) Subject to (b), below, secondary containment shall be provided for all underground piping systems that routinely contain regulated substances or their vapors by using double-wall piping.
2. (b) Vent piping shall be exempt from (a), above.

3. (c) All piping and dispenser sumps shall be:

   1. (1) Liquid-tight to contain liquids;
   2. (2) Installed to prevent the intrusion of groundwater or surface water runoff; and
   3. (3) Equipped with liquid-tight penetration fittings for all sump entries.

4. (d) All piping and dispenser sump sensors shall be installed:

   1. (1) To respond to small accumulations of liquids within the sumps;
   2. (2) In the lowest portion of the sump; and
   3. (3) In accordance with the manufacturer’s requirements for installation.
5. (e) Subject to (f), below, all piping that is inside a building and part of the interior piping system shall have secondary containment and leak monitoring that meets the requirements of (a) through (d), above.
6. (f) For piping that is inside a building, an engineered pipe trench system may be used as secondary containment in lieu of double-wall piping.

Source. (See Revision Note #1 at chapter heading for Env-Or 400) #10393, eff 9-1-13; ss by #12643, eff 10-10-18 (See Revision Note #2 at chapter heading for Env-Or 400)