PERMFILE59460

• Permit No: M2006003
• IBM Index Class Name: Permit File
• Doc Date: 5/12/2006
• Doc Name: 05/08/06 Groundwater Model Review
• From: Civil Resources LLC
• To: DMG
• Media Type: D
• Archive: No

es c J ~l ~,d,ti, ~~%~-~`-
IVIL RES"~URCES, LLC
ENGINEERS 5 PLANNERS
May 9, 2006
REDEI'~/ED
~(AY f 2 20~
Ms. Erica Crosby
Division of Minerals and Geology
1313 Sherman Street, Room 215
Denver, Colorado 80203
r/di~iga ei Mi„pa,,,yd
RE: Hall•Irwin Corporation, Application No. M•2006.003
ParkerlDersham Sand and Gravel Resource; May 8, 2006 Groundwater Model Review
Dear Ms. Crosby:
Following is our response to your Adequacy Review dated May 8, 2006, Groundwater Model Review, °Parker-
Dersham Gravel Mine', Hall-Irwin Corporation File M-2006-003, Class: Permit
1. The applicant must commit to a groundwater level monitoring program with monthly water level
measurements at the six (6) existing piezometers throughout the life of the operation, or until such
time that the Division determines that the monitoring schedule of groundwater levels at the Parker
Dersham Gravel Mine may be revised or is no longer needed.
Hall-Irwin commits to monitor groundwater levels monthly at the six existing piezometers throughout the life
of the mine, or until such time that the Division determines that the monitoring schedule of groundwater
levels at the Parker-Dersham Gravel Mine maybe revised or is no longer needed. Hall-Irwin will submit
this information to the Division with their annual report or upon request. If groundwater levels drop below
the trigger level the Division will be notified.
2. The applicant must commit to an action level or "trigger" that will prompt the need for mitigation
measures to be implemented. (The Division suggests that the applicant consider a trigger of 3'
beyond the observed baseline groundwater elevation, as the natural seasonal fluctuation at most
piezometers appears to be 2').
The applicant will'commit to a trigger response in the event the mining phase of the operation causes a
drawdown of three feet or greater. The miner will first install a temporary piezometer near the neighboring
well and water level readings will betaken everyday for one week to determine if the water level reading is
accurate (unless it is observed that immediate action is necessary). Surrounding groundwater stresses
(other mines dewatering, farmers running pumps) will be taken into account during this week observation
period. The average observed water level and the surrounding stresses will than be used to determine the
correct mitigation measures per the Section 4.2.1 in the Groundwater Study.
3. The applicant must specify provisions for reporting of action levels encountered during mining as
well as the reporting of annual water monitoring data and summary results to the Division. The
applicant may also want to specify measuring criteria to be used to verify that a true exceedance of
an action level has occurred.
451 OAK STREET, SUITE 209 • FREDERICK, COLORADO 80530 • PHONE: [phone] • FAX: [phone]