2018-01-19_HYDROLOGY - M1977348

• Permit No: M1977348
• IBM Index Class Name: HYDROLOGY
• Doc Date: 1/19/2018
• Doc Name Note: 2nd Semi-Annual 2017 Groundwater Sampling
• Doc Name: 2nd Semi-Annual 2017 Groundwater Sampling
• From: Golder Associates for Holcim ‎(US)‎ Inc.
• To: DRMS
• Email Name: AME
• Media Type: D
• Archive: No

f?,
Golder
Associates
January 16, 2018 1772432
Ms. Amy Eschberger
Colorado Division of Reclamation Mining and Safety
Department of Natural Resources
1313 Sherman Street, Room 215
Denver, Colorado 80203
RE: SECOND SEMI-ANNUAL 2017 GROUNDWATER SAMPLING EVENT 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 second 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-3 (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.
Recent water levels, taken in May and November 2017 after more than six months of recharge, are higher
than the previous range of levels observed 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.
✓ 1 4..4.c-4-.
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
1772432 BoettcherQuarryGWSamp2Q2017 Fnl 16Jan18 docx
Golder Associates Inc.
44 Union Boulevard,Suite 300 �1
Lakewood,CO 80228 USA •
Tel:[phone] Fax*[phone] www golder.com
Golder Associates:Operations in Africa,Asia,Australasia,Europe,North America and South America
Golder,Golder Associates and the GA globe design are trademarks of Golder Associates Corporation