C.M.R. 06, 096, ch. 691, app 096-691-F
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:
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.
C.M.R. 06, 096, ch. 691, app 096-691-F