Code of Maine Rules
06 - DEPARTMENT OF ENVIRONMENTAL PROTECTION
096 - DEPARTMENT OF ENVIRONMENTAL PROTECTION - GENERAL
Chapter 695 - RULES FOR UNDERGROUND HAZARDOUS SUBSTANCE STORAGE FACILITIES
Appendix 096-695-B - Installation Requirements Applicable to New and Replacement Tanks

1. Cathodically protected steel tanks must be set on a firm base and surrounded on all sides with at least 12 inches of noncorrosive inert material, such as clean sand, pea stone, or gravel, well tamped in place. The tanks shall be placed in the hole with care, making sure not to scrape the protective coating off coated tanks, or damage attached cathodic protection components. Cathodic protection systems require electrical wiring which is connected to the tank and shall be accessible for voltage readings at the ground surface as well as a location along the centerline of the tank to place a reference electrode in contact with the soil. If soil is to be covered by asphalt, concrete, or other materials then a test station must be installed over the center of the tank to provide access to the soil for cathodic protection monitoring.

NOTE: To facilitate future precision testing in the event that a leak is indicated, the owner or operator may install access to tank openings for vapor pocket removal, and a monitoring well to determine the location of the water table.

2. Cathodically protected steel underground tanks shall be covered with a minimum of 2 feet of sand, pea stone or gravel or shall be covered with not less than 1 foot of sand on top of which shall be placed a slab of reinforced concrete not less than 4 inches thick. This fill shall be free of debris, boulders. large rocks or other materials, which may cause abrasions to the protective coating of the tank. When tanks are, or are likely to be, subjected to traffic, they shall be protected from damage from vehicles passing over them by at least 3 feet of backfill or, 18 inches of well-tamped backfill plus 6 inches of reinforced concrete of 8 inches or asphalt paving. When asphalt or reinforced concrete paving is used as part of the protection, it shall extend at least I foot horizontally beyond the perimeter of the tank in all directions.

3. All underground hazardous substance storage tanks shall be installed in accordance with the manufacturer's instructions. The minimum depth of cover shall be as specified in paragraph 2 above.

4. New underground tanks shall be pneumatically tested for tightness in conformance with the requirements of Appendix C before being covered or placed in use. Alternative testing methods may be used if approved by the Department.

NOTE: Air pressure testing shall not be conducted after a hazardous substance has been placed in the tank unless approved in writing by the Department. Air pressure testing after certain hazardous substances have been in contact with the tank may result in explosion of the tank.

5. All temporary supports must be removed prior to final backfilling.

6. All electrical wiring shall be performed in accordance with the current State of Maine electrical code.

7. Anchoring of tanks shall be required where tanks will be installed in areas where groundwater will be in contact with the tank. When anchoring tanks equipped with cathodic protection the hold downs must be electrically isolated from the tank. Anchoring of all tanks shall be performed in accordance with the tank manufacturer's specifications.

NOTE: Tank installation instructions may require specific aggregate sized peastone or gravel. Instructions may also specify mechanical compaction or layered placement of bedding and backfill. Always consult the installation instructions provided by the manufacturer, prior to installation.