2017-08-04_HYDROLOGY - M1977348

• Permit No: M1977348
• IBM Index Class Name: HYDROLOGY
• Doc Date: 8/4/2017
• Doc Name: Water Monitoring - Groundwater
• From: Golder Associates
• To: DRMS
• Email Name: AME
• Media Type: D
• Archive: No

V
1 = Golder
Associates
' July 31, 2017 1772432
' Ms. Amy Eschberger AUG 0 4 2017
Colorado Division of Reclamation Mining and Safety DIVISION OF RECLAMATION
Department of Natural Resources MINING AND SAFETy
1313 Sherman Street, Room 215
Denver, Colorado 80203
-7 RE: FIRST SEMI-ANNUAL EVENT 2017 GROUNDWATER SAMPLING AT THE BOETTCHER
QUARRY
Dear Ms. Eschberger:
' On behalf of Holcim (US) Inc., Golder Associates Inc. is pleased to submit analytical laboratory results for
the first semi-annual 2017 groundwater sampling event at the Boettcher Limestone Quarry near La Porte,
Colorado. Attached are Tables 1 through 7, summarizing the results, and a copy of the laboratory report.
In addition to sampling wells MW-1 through MW-7, a field duplicate at MW-1 (MW-20) and a field blank
(MW-15)were collected. The locations of monitoring wells MW-1 through MW-7 are presented in Figure 1.
In December 2016, the Colorado Division of Reclamation Mining and Safety approved a revision to change
the required groundwater monitoring frequency from quarterly to semi-annually (Revision TR07) based on
evidence that the groundwater wells were not fully recharging between sampling events. Figure 2 presents
a graph of the monitoring well water elevations measured during each sampling event from 2013 to present.
The most recent water levels, taken in May 2017 after more than six months of recharge, are higher than
the previous range of levels observed on site for wells that are purged dry prior to sampling (MW-2, MW-3,
MW-4, MW-6, and MW-7), indicating more recharge, and further evidence that the groundwater wells were
not fully recharging between sampling events.
If you have any questions, please call the undersigned at(303) 980-0540.
Sincerely,
GOLDER ASSOCIATES INC.
P_ . r,)q 1
Sara Harkins, PG Randy March, PE, PG
' Geologist Principal Geological Engineer
Attachments: Table 1 —Summary of Monitoring Results for MW-1
Table 2—Summary of Monitoring Results for MW-2
Table 3—Summary of Monitoring Results for MW-3
Table 4—Summary of Monitoring Results for MW-4
Table 5—Summary of Monitoring Results for MW-5
Table 6—Summary of Monitoring Results for MW-6
Table 7—Summary of Monitoring Results for MW-7
Figure 1 — Location Map
Figure 2—Groundwater Elevations vs. Time
Attachment 1 —ACZ Laboratory Report
SH/RM/rjg
' 1772432 BoeticherQuarryGMamp1 Q2017 Fn1-28Ju117 docx
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