7 Del. Admin. Code § 1352-B-6.0

Current through Register Vol. 28, No. 7, January 1, 2025

Section 1352-B-6.0 - Design, Construction, and Repair Requirements for Underground Piping

6.1 General Requirements for New Underground Piping

6.1.1 All underground piping installed after June 11, 2004 shall comply with the requirements of this Section.

6.1.2 All underground piping, fittings and connections that are either in contact with the regulated substance or completely buried shall:

6.1.2.1 Be constructed of fiberglass reinforced epoxy, carbon steel, thermoplastic material extrusions, stainless steel, or galvanized steel; or

6.1.2.2 Be constructed of other materials as approved by the Department.

6.1.3 All underground piping and piping secondary containment materials shall be compatible with the Regulated Substance that is to be stored in the AST.

6.1.4 The underground piping layout shall be designed to minimize crossed lines and interference with conduit and other AST components. If crossing of lines is unavoidable, adequate clearance shall be provided to prevent contact.

6.1.5 All fill pipes leading to a pump-filled AST shall be equipped with a properly functioning check valve or equivalent device which provides automatic protection against backflow whenever the piping arrangement of the fill pipe is such that backflow from the AST is possible.

6.1.6 Each AST connection through which a regulated substance can normally flow shall be equipped with an operating isolation valve to control flow unless the AST connection is located at a point higher than the highest liquid level in the AST, such as at the top of a horizontal AST. The valve shall be located on a nozzle welded to the shell of the AST.

6.1.7 Pipe joints shall be cut accurately and deburred to provide liquid-tight seals. No threaded or flanged connections shall be in contact with the soil.

6.1.8 New underground piping systems shall be designed, constructed, and installed with access and isolation points to permit pressure testing of piping without the need for excavation.

6.1.9 Copper or brass tubing or malleable iron shall not be used in AST underground piping.

6.1.10 All new underground piping shall be tested in accordance with API 570 prior to introduction of any regulated substance into the piping.

6.1.11 Metallic underground piping that penetrates earthen or concrete dike walls or other structures shall be sleeved and electrically isolated from the sleeve.

6.2 Requirements for New Non - Metallic Underground Piping

6.2.1 New Non-metallic underground piping shall be designed and constructed in accordance with:

6.2.1.1 ASTM Specification D-2996, Standard Specification for Filament Wound RTRP; and

6.2.1.2 UL 971, Standard for Nonmetallic Underground Piping for Flammable Liquids.

6.2.2 The ultimate shear strength of all adhesive and curing agents shall be in compliance with ASTM D-2517, as approved and supplied by the manufacturer.

6.2.3 Thermoplastic extrusion flexible underground piping shall be designed and constructed in accordance with:

6.2.3.1 UL 971, Standard for Nonmetallic Underground Piping for Flammable Liquids.

6.2.4 Other non-metallic underground piping may be approved by the Department.

6.3 Requirements for New Steel Underground Piping

6.3.1 New Steel Underground Piping:

6.3.1.1 Shall be standard weight or heavier; and

6.3.1.2 Shall be installed in accordance with:

6.3.1.2.1 API Recommended Practice 1615, Installation of Underground Petroleum Storage Systems; and

6.3.1.2.2 ASME B31.1, Power Piping; and

6.3.1.2.3 ASME B31.3, Process Piping; and

6.3.1.2.4 ASME B31.4, Pipeline Transportation Systems for Liquids and Slurries; and

6.3.1.3 Shall have a protective coating and be cathodically protected in accordance with PART B, subsection 6.5; or

6.3.1.4 Shall have non-metallic secondary containment; or

6.3.1.5 Shall have metallic secondary containment that shall have protective wrapping or dielectric coating and shall be cathodically protected by an Impressed Current Cathodic Protection System or Sacrificial Anode Cathodic Protection System unless the metallic secondary containment is not in contact with the soil and is in a non-corrosive environment; or

6.3.1.6 Shall not require the addition of cathodic protection if the steel Underground Pipe is not in contact with the soil and is in a non-corrosive environment.

6.4 Requirements for New Other Metallic Underground Piping

6.4.1 Metallic underground piping other than steel shall:

6.4.1.1 Be schedule 40 or heavier thickness; and

6.4.1.2 Be approved by the Department prior to installation.

6.5 Requirements for Corrosion Protection for New Steel Underground Piping

6.5.1 Corrosion protection for steel underground piping in contact with the soil shall:

6.5.1.1 Consist of a Sacrificial Anode Cathodic Protection System or an Impressed Current Cathodic Protection System designed, fabricated, and installed in accordance with nationally recognized standards including but not limited to API RP651, and NACE SP0169; and

6.5.1.2 Have a Cathodic Protection System designed by individuals who have obtained a NACE Cathodic Protection Specialist Certification and have relevant work experience in the design of Cathodic Protection Systems for Underground Piping; and

6.5.1.3 Be designed to provide corrosion protection for the expected active life of the AST system or have provisions to allow for the periodic rehabilitation of the Cathodic Protection System; and

6.5.1.4 Have a test station or other method of monitoring which enables the Operator to confirm that the Cathodic Protection System is operating properly.

6.5.2 Measurements of Underground Pipe-to-soil potential shall be made no sooner than 60 days and no later than 180 days after installation of the Cathodic Protection System in accordance with the requirements of PART C, Section 5.0.

6.6 Requirements for Backfill Material for New Underground Piping Installations

6.6.1 Backfill material adjacent to the underground piping shall consist of sand or pea gravel. The material shall be clean, washed, inert, free flowing, homogeneous, well granulated, non-corrosive, and free of debris, rock, ice, snow or organic material. Particle length shall be no more than 3/8-3/4" in size and shall comply with the manufacturer's specifications. Mixing of the backfill adjacent to the underground pipe with native substance and/or foreign objects is prohibited.

6.7 Repair Requirements for Underground Piping

6.7.1 Any repairs to Underground Piping shall be made to meet or exceed standards of the original condition of the underground piping.

6.7.2 At any time excavation of soil or removal of concrete, asphalt, or other cover is required during the course of a Repair, Owners and Operators shall perform soil sampling and analysis in accordance with those requirements identified in DERBCAP to measure for the presence of a Release where contamination is most likely to be present at the AST site.

6.7.3 Within 90 days of completion of a Repair of underground piping Owners and Operators shall submit documentation to the Department including the following:

6.7.3.1 Repair completion documentation; and

6.7.3.2 Results of Tier 0 sampling requirements specified in DERBCAP; and

6.7.3.3 Results of any piping tests required by the Department.

6.7.4 An Owner or Operator may repair holes in underground pipe and fittings with repair methods that include but are not limited to patching, welding, or clamping and that are made in accordance with manufacturer's specifications and applicable industry standards as a temporary repair not to exceed 30 days. After 30 days with a temporary repair the underground piping shall be permanently repaired or shall be taken Out of Service.

6.7.5 Permanent repairs shall be:

6.7.5.1 Replacement of the affected section of underground pipe, or

6.7.5.2 Full welded encirclement of the affected section of underground pipe.

7 Del. Admin. Code § 1352-B-6.0

20 DE Reg. 815 (4/1/2017)
27 DE Reg. 536 (1/1/2024) (Final)