2011-11-08_PERMIT FILE - C1981041A ‎(4)‎

• Permit No: C1981041A
• IBM Index Class Name: Permit File
• Doc Date: 11/8/2011
• Section_Exhibit Name: Tab 18 Surface Water Monitoring Plan
• Media Type: D
• Archive: Yes

evaluate stability as a result of higher than expected water levels in the pile. Their
evaluation was inconclusive due to the piezometers being open the full length of the
hole. Western Engineers was retained to do further evaluation of stability including
installation of piezometers isolated to narrow water bearing zones within the pile.
Thirty piezometers (PZ 100 -107, 200 -206, 300 -307, and 400 -406) were installed at
four locations on the pile. Multiple 1/2" diameter piezometers were installed in each
bore hole. The bottom of each piezometer was perforated and sand packed through
a wet zone identified while drilling. The multiple zones within the hole were
separated by bentonite plugs. Stability was verified in the pile at the measured water
levels but the study recommended quarterly monitoring of the piezometers for
continued evaluation. A listing of these piezometers is given on Table 18 -4. The
water levels are measured quarterly on these piezometers. The study established
"critical target depths ", Table 18 -4, at which stability of the pile could again be in
question. Results of quarterly monitoring are evaluated against the critical target
depths and the Division will be notified within 2 days if measured levels are above the
critical target depths. If that occurs the stability of the pile will be reevaluated and
corrective action taken if necessary. Piezometers CRDA -01 through 06 and 01 a are
monitored quarterly for water level. The sixteen temporary piezometers were
eliminated during the pile cover project in 1994.
Four piezometers were installed around the Unit Train L•oadout to monitor water
levels in the alluvial material. Monitoring of these piezometers (UTL -01, 02, 03, and
04) was generally done monthly from March 1984 through September 1987.
Monitoring of water levels was discontinued in 1987. Quarterly water level monitoring
was resumed on the 4 piezometers in 1994 and annual quality monitoring was started
on UTL -02 and 04 for the parameters listed in Table 18 -3 for ground water. Monitoring
of the UTL piezomenters was discontinued with the approval of SL -7 in April 2011.
UTL 01, 02, 03 and 04 wells were abandoned and reclaimed in May 2011.
A former mine dewatering pipe is being used to monitor the water level in the
north end of the Roadside South Portals mine. This piezometer, N -1, which is located
in the old North Decline area is monitored quarterly.
TR -62 18 -5 Rev 07/11