7 Del. Admin. Code § 1352-B-7.0
Current through Register Vol. 28, No. 7, January 1, 2025
Section 1352-B-7.0 - Design and Construction Requirements for Secondary Containment and Spill Containment for New ASTs7.1 General Requirements for Secondary Containment for ASTs. 7.1.1 Secondary containment shall be required for all new ASTs.7.1.2 Secondary containment shall not be used to store materials. The secondary containment shall be used to collect spills or leaks, which shall then be promptly removed, in accordance with appropriate disposal and safety procedures.7.1.3 If not roofed or otherwise protected from the accumulation of precipitation, the secondary containment area shall be equipped with a manually-controlled pump or siphon or a gravity drain pipe which has a manually-controlled valve, to remove precipitation that collects within the secondary containment system to a Department approved location.7.1.4 Secondary containment shall be designed and constructed to retain any regulated substance that leaves the primary containment including an AST and ancillary piping and prevent any regulated substance from reaching the surface water, groundwater, or adjacent land before cleanup occurs.7.1.5 All drainage valves located within the secondary containment system shall remain closed at all times except during controlled drainage events. Secondary containment systems may be equipped with regulated substance sensors that shall automatically close all drainage valves in the event of a leak with prior approval of the Department.7.1.6 ASTs installed between June 11, 2004 and the most recent effective date of this regulation, shall have all regulated substance transfer areas equipped with a spill containment system capable of containing and collecting those spills and overfills and preventing a release where filling connections are made with vehicles.7.1.7 All regulated substance transfer areas where filling connections are made with vehicles shall be capable of containing and collecting 110% of the volume of the largest compartment of the largest vehicle that may be utilized and preventing a Release for all new ASTs installed and for all ASTs brought into service,7.2 Secondary Containment Options for ASTs 7.2.1 Requirements for Diking Configuration as secondary containment 7.2.1.1 Dikes shall be constructed of materials compatible with the contents of the AST and which shall retain any Regulated Substance that leaves the primary containment including an AST and ancillary piping and prevent any regulated substance from reaching the surface water, groundwater, or adjacent land before cleanup occurs.7.2.1.2 There shall be no openings or unsealed penetrations of the walls or floor of the dike. Any exceptions will be AST specific and shall require Department approval.7.2.1.3 All dikes shall have a minimum capacity to contain 110% of the volume of the largest AST within the diked area or 100% of the volume of the largest AST plus six inches of freeboard for precipitation, regardless of engineering controls or design.7.2.1.4 The extent of the diked area shall be sufficient to capture overflows, splashing caused by overfilling and/or the trajectory of sidewall leaks.7.2.1.5 Sumps shall be installed as part of all dikes and the dike floors sloped to the sumps to enhance material removal.7.2.1.6 Pumps which are permanently installed for the removal of collected material to areas outside the dike area shall be locked in the off position when not in use and shall be monitored when in use to avoid discharging regulated substances to the environment. Portable pumps which are used for the removal of collected material to areas outside of dikes shall be monitored while in use to avoid discharging regulated substances to the environment. Pumps which discharge material back to the ASTs within the diked area need not be locked when not in use, but pumps which pump in either direction shall have valve locks to control discharges outside the dike, and when discharging outside the dike shall be monitored.7.2.1.7 An inspection and maintenance plan shall be developed to periodically review the condition of the secondary containment system.7.2.1.8 A permanent walkway, stairway or ramp shall provide access to prevent dike wall degradation.7.2.2 Requirements for Curbing/Paving as Secondary Containment7.2.2.1 The paving/curbing combination, to be considered secondary containment, shall have a minimum capacity to contain 110% of the volume of the largest AST, or 100% of the volume of the largest AST plus six inches of freeboard for precipitation, or be able to direct spilled or leaked materials to a containment structure that meets these requirements, regardless of engineering controls or design.7.2.2.2 The curbing and/or paving shall be constructed of materials compatible with the contents of the ASTs around which they are installed. If necessary, the curbing and paving shall be coated with a protective material.7.2.2.3 To provide a liquid tight seal, curbing shall be installed as either part of the paving (integrally poured) or, if installed later, shall have a liquid barrier included in the installation.7.2.2.4 The extent of the curbed area shall be sufficient to capture overflows, splashing caused by overfilling and/or the trajectory of sidewall leaks.7.2.2.5 Sumps shall be installed as part of all curbs and the floors sloped to the sumps to enhance material removal.7.2.3 Requirements for Underground Vaults as Secondary Containment 7.2.3.1 A Vault shall completely enclose the AST and shall be constructed of materials compatible with the regulated substance to be contained in the AST and shall have a minimum capacity to contain 110% of the volume of the largest AST.7.2.3.2 All lines to and from ASTs installed in Vaults shall pass through the roof of the Vault. No lines shall penetrate the walls or floor of the Vault.7.2.3.3 Each AST shall have its own Vault. Adjacent ASTs may share common walls.7.2.3.4 Vaults shall be designed according to sound engineering practices.7.2.3.4.1 The floor shall be designed and constructed to withstand stress resulting from fully loaded ASTs within the Vault.7.2.3.4.2 The top, walls, and floor shall be designed to withstand the anticipated loading including loading from traffic, soil, and groundwater.7.2.3.4.3 The Vault shall be constructed to be liquid tight.7.2.3.5 The AST and Vault shall be suitably anchored to withstand uplifting by either water or a regulated substance, including when the AST is empty.7.2.3.6 The only openings in a Vault are those necessary for access, inspection, filling, emptying, and venting of the AST.7.2.3.7 There shall be no backfill around the AST and there shall be sufficient space between the AST and the vault to allow inspection of the AST and equipment. ASTs designed for underground use shall not be used in Vaults.7.2.3.8 Each vault shall be equipped with Continuous Leak Detection and be capable of detecting vapors and liquids.7.2.3.9 A means to admit a suitable fire suppression agent shall be provided for each vault that contains flammable or combustible substances.7.2.3.10 Each vault shall have a means for personnel entry.7.2.4 Requirements for Double-walled ASTs as Secondary Containment 7.2.4.1 A double walled AST may be used to fulfill the requirements for secondary containment if the AST is installed with all of the following:7.2.4.1.1 Overfill prevention as required in PART B, Section 8.0; and7.2.4.1.2 Leak detection as required in PART B, Section 9.0; and7.2.4.1.3 Where an AST roof is involved, the outer wall of the double walled AST shall be designed to contain 100% of the volume of the AST. If there is an open top, the total containment shall be constructed to contain 110% of the volume of the largest AST within the system or 100% of the volume of the largest AST plus six inches of freeboard for precipitation, regardless of engineering controls or design.7.2.4.2 The outer containment wall shall be compatible with and capable of containing the regulated substance stored.7.2.5 Requirements for Secondary Containment External Liners 7.2.5.1 Secondary containment external liners shall be constructed and maintained to retain any Regulated Substance that leaves the primary containment including an AST and Ancillary Piping and prevent any Regulated Substance from reaching the surface water, groundwater, or adjacent land before cleanup occurs for the operational life of the ASTs.7.2.5.2 External lining materials shall be compatible with the regulated substance stored in the AST.7 Del. Admin. Code § 1352-B-7.0
7 DE Reg. 1765 (06/01/04)
20 DE Reg. 815 (4/1/2017)
27 DE Reg. 536 (1/1/2024) (Final)