2007-08-31_REVISION - M1977208

• Permit No: M1977208
• IBM Index Class Name: Revision
• Doc Date: 8/31/2007
• Doc Name: TR-09, Submittal
• From: Cemex
• To: DRMS
• Type & Sequence: TR9
• Media Type: D
• Archive: No

C-PIT Hydrogeologic Investigations
Technical Revision No. 8
3: Observations and Results Mining Permit M-1977-208
Although a single water sample was obtained From compliance well CEM-005, the results shown on Table 2
are not considered to be representative of formation water. This water is presumed to be residual water from
the well drilling process.
3.3 Boulder Feeder Canal Gauging Results
Brown and Caldwell conducted two flow measurements on the reach of the Boulder Feeder Canal located to
the west of the C-Pit Site on July 19, 2007. No quantification of seepage losses from the canal could be made
from this exercise.
The stream gauging calculations indicate the flow rate at the upstream measurement station was 86.2 CFS,
and flow at the downstream station was calculated to be at 88.1 CFS. The difference in these values is
approximately 2 percent, which is within the range of expected accuracy for the methods employed. The
operator of the ditch, NCWCD, reported the flow rate at the 10-foot flume located on the canal upstream of
C-Pit and immediately east of Highway 36 (Foothills Parkway) was 89 CFS at the time of gauging.
3.4 Compliance Well CEM-005
It is Brown and Caldwell's opinion that the most recent fieldwork conEtrms that the water currently in
CEM-005 is likely residual water remaining from the drilling process and draining from the surrounding sand
pack. Although a sample was obtained from CEM-005 in May 2005, there is no apparent hydraulic
connection between C-Pit and well CEM-005. The water elevation in C-Pit and potentiometric level in
monitoring well CEM-001 axe approximately 390 feet higher than the measured water elevation in CEM-005.
CEMEX continues to monitor the water level in CEM-005 to conEtrm the existing information.
3.5 Geochemical Evaluation
Stiff diagrams and Piper plots were prepared from the available surface and groundwater chemisny data for
C-Pit, the monitoring wells, piezometex P-003 and the Boulder Feeder Canal Figures 10 and 11 display the
plotted data.
The ground and surface water geochemistry signatures of alluvial well CEM-004 and the Boulder Feeder
Canal appear to be tin-impacted, and likely represent meteoric water or water with very little contact time with
rocks in the area. This is evident by the low total dissolved solids (TDS) relative to the other samples.
The six water samples each plot as different water types, indicating a relatively isolated and discontinuous
groundwater flow system fox this Site:
1. CEM-004 (the alluvial well northeast of C-Pit) is a calcium bicarbonate water type.
2. The Boulder Feed Canal is a calcium bicarbonate water type.
3. C-Pit water is asodium-potassium sulfate water type.
4. CEM-001 water is asodium-potassium chloride water type.
5. CEM-003 is asodium-potassium bicarbonate water type.
6. P-003 is a calcium sulfate water type.
Although a hydraulic connection exists between C-Pit and monitoring well CEM-001 to the east, the
geochemical signatures of the water at these two locations are signiEcandy different Moreover, the C-Pit
geochemical signature changed over time following the placement of fill into the pit beginning in March 2007.
The pH of the pit water shifted from approximately 12.3 to 8.0 (su) during this period, and calcium, sodium,
3-3
Use of contens on Ihis sheet rs subled to the limitations specdiad at the end of this document
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