Yes. One involves changes in bedrock Well H. The water level of this well is usually about 10 feet above the level of the Berkeley Pit, just like other bedrock wells nearby. But one July, Well H’s level started falling, and by September it had dropped about 3 ½ feet. Meanwhile, the Pit kept rising. From December through February, the water levels of the Pit and Well H were just inches apart. Well H is now gaining on the Pit again.
What is the significance of the surprise reading in Well H? It appears to be an isolated incident caused by underground subsidence (shifting of dirt) adjacent to the well. Well H is southeast of the Pit in the middle of the old Pittsmont Mine workings, where the ground is known to be unstable. The water levels in all of the surrounding bedrock wells remain high, indicating that flow is still toward the Pit. It is important to look at the monitoring well system as a whole, rather than focus solely on the performance of a single well.
And Well H is not the only surprise to date. In 1989, the water level in the Kelley shaft dropped two feet in one month, but it, too, recovered. Well DDH-5 also occasionally fluctuates. The monitoring program was set up specifically to detect changes like these. When something unusual turns up, monitoring is heightened at that spot, and scientists determine what action, if any, needs to be taken. At Well H, water levels have been checked weekly since October. On February 18, a special camera was lowered 927 feet into the well to look for abnormalities, and none were found.
Future years will bring many more monitoring well changes, especially in the area between the Berkeley and Continental Pits.