PERMFILE138823

• Permit No: M2006003
• IBM Index Class Name: Permit File
• Doc Date: 4/28/2006
• Doc Name: Groundwater Reports
• From: Civil Resources
• To: DMG
• Media Type: D
• Archive: No

settling ponds were set with constant heads approximately 5 feet below the ground surface were use to simulate existing
conditions on the Site and surrounding the Site.
Table 8
Mining Scenario
Phase Pro ert /Site
Parker Dersham Bri hton Pif
M1 Dewater/Mine NA Reclaimed
M2 Reclaimed Slur WaIVMine Reclaimed
Rf Reclaimed Reclaimed Reclaimed
Notes:
i. Dewatering occurs in conjunction with mining.
2. Input parameters used to calibrate the steady-state model were maintained during the
mining scenario simulation.
3. Dewatedng was modeled using conslant heads.
For example, a run done for Phase M1 would be modeled with: l) the Parker piece fully dewatered and mined and 2) the
Dersham piece left alone and the Brighton Pit and setting ponds as existing conditions. Arun for each phase in Table 8
was performed and the results are reported in Table 9.
The model indicates that the dewatering phases of the mining operation could result in fluctuating water levels in some
wells close to the areas being dewatered. Table 9 reports the approximate fluctuations in the existing groundwater
levels due to dewatering during each mining phase. Due to the complex nature of the Site and the Site's surroundings
(existing gravel pits, unlined water storage ponds and slurry wall lined gravel pits) groundwater levels fluctuated
differently for each mining phase. The resulting water levels during each phase of mining are reported in Table 9 below.
Table 9
Mining Groundwater Level Table
Location (1) 0.5 miles
northwest (2) 0.3 miles
west (3) 0.1 mile
north (4)1 mile
north (5) 0.5
miles east (6) 0.9 miles
south
Grid Location 33,19,1 46,19,1 25,27,1 19,28,1 49,55,1 85,30,1
Phase
Ground
Surface
Elevation 4950 4954 4940 4939 4944 4957
Existin WSE 4926.5 4927.7 4928.4 4928.5 4936.7 4944,4
Baseline 4935.61 4937.8 4934.22 4930.6 4936.7 1946,8
Mine 1 WSE 4918.1 4926.0 4921.8 4926.7 4936.7 4944,4
Mine 2 WSE 4937.7 4942.1 4935.2 4931.3 4936.7 4944,4
Notes:
- Locations are all relative to the middle of Ne Site.
-Ground Surface Elevation is approximate and used for reference.
-Approximate location of water level, Water Surface Elevation (WSE).
-Existing WSE is the water level after calibration.
- M1-M2 indicates water level at location after the particular mining phases have begun.
-Groundwater levels compared to Baseline.
Groundwater Model Report -Hall-Irwin Parker-Dersham Site - 6 - April 2006