Code of Maine Rules › 06 - DEPARTMENT OF ENVIRONMENTAL PROTECTION › 096 - DEPARTMENT OF ENVIRONMENTAL PROTECTION - GENERAL › Chapter 691 - RULE FOR UNDERGROUND OIL STORAGE FACILITIES › Appendix 096-691-F - Specifications and Requirements for Vertical Ground Water Monitoring Wells at Existing Facilities

Current through 2024-29, July 17, 2024
These requirements only apply to existing facilities, fully
				  installed as of April 19, 1990.
1. Sufficient number of vertical ground water monitoring
				  wells must be installed to detect a leak from every tank by including a minimum
				  of four monitoring wells for each tank or where more than one tank is installed
				  in the same continuous excavation, the minimum number of monitoring wells shall
				  be installed as diagrammed below:
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When more than one tank is installed in a continuous
				  excavation hole, alternate numbers and positioning of ground water monitoring
				  wells may be used when determined by a Maine licensed professional engineer or
				  Maine certified geologist as capable of detecting a leak or discharge from
				  every tank and meeting the performance and installation requirements of section
				  5(C) of this Chapter.
				  Such an alternate ground water monitoring plan must be certified by a Maine
				  licensed professional engineer or Maine certified geologist, and submitted to
				  the Commissioner as part of the facility's registration materials.
2. Monitoring wells must be a minimum of 2 inches in
				  diameter.
3. The slotted zone must extend at least 5 feet into the
				  water table and at least 5 feet above the groundwater surface, as determined at
				  the time of installation; or when installed within a secondary containment
				  liner, the slotted zone must extend to within 6 inches of the low point of the
				  liner.
4. The screened portion of the well must be a minimum of 10
				  feet in length and must be factory slotted with a slot size of .010
				  inch.
5. Monitoring wells must be installed with a cap at the
				  bottom of the slotted section of the well.
6. Monitoring wells must not be constructed of schedule 20
				  PVC "sewer" or leach field piping.
7. Monitoring wells must be constructed of flush joint,
				  threaded schedule 40 PVC or other materials and designs approved by the
				  Commissioner.
8. Monitoring wells must be numbered such that all monitoring
				  and testing results are easily correlated to a specific monitoring well
				  location.
9. All monitoring wells must be equipped with liquid-proof
				  lockable caps.
10. Monitoring wells must be properly distinguished from fill
				  pipes.
11. The area around the screened portion of the well shall be
				  surrounded by a porous medium (e.g. sand, gravel or pea stone).
12. The outside of the monitoring wells risers must be sealed
				  using bentonite or a similar product to a depth of 1 1/2 feet below ground
				  surface.
13. Monitoring wells located in traffic areas must be cut off
				  at ground level, clearly marked, and fitted with a limited access cover in
				  accordance with PEI Publication RP 100 or properly protected from
				  vehicles.
14. Any damaged monitoring well must be repaired or replaced
				  as soon as possible after discovery of the damage, but at least within 45
				  days.
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