2021-03-16_HYDROLOGY - M1977348

• Permit No: M1977348
• IBM Index Class Name: HYDROLOGY
• Doc Date: 3/16/2021
• Doc Name Note: Event
• Doc Name: Water Monitoring - Groundwater
• From: Golder Associares, Inc.
• To: DRMS
• Email Name: AME
• Media Type: D
• Archive: No

GOLDER
' March 11, 2021 Reference No. 20144265-5-L-0
RECEIVED
' Ms. Amy Eschberger MAR 7 b 2021
Colorado Division of Reclamation Mining and Safety
Department of Natural Resources DIVISION OF RECLAMATION
' 1313 Sherman Street, Room 215 MINING AND SAFETY
Denver, Colorado 80203
' SECOND SEMI-ANNUAL 2020 GROUNDWATER SAMPLING EVENT AT THE BOETTCHER QUARRY
' Dear Ms. Eschberger:
On behalf of Holcim (US) Inc., Golder Associates Inc. (Golder) is pleased to submit analytical laboratory results
' for the second semi-annual 2020 groundwater sampling event at the Boettcher Limestone Quarry near La Porte,
Colorado. Attached are Tables 1 through 8, summarizing the results, and a copy of the laboratory report
(Attachment 1). Field sheets for the purging and sampling are presented in Attachment 2. In addition to sampling
' wells MW-1 through MW-8, 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-8 are presented in Figure 1. The second semi-annual 2020
groundwater sampling event was the first time MW-8 was sampled.
' 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.
Upon receipt of the laboratory reports, Golder reviewed the results, and a general analytical data evaluation was
' performed. Results of this evaluation included the following:
■ The samples were received by the laboratory at the appropriate temperature.
■ The required analyses were performed.
■ The analyses were conducted within their respective United States Environmental Protection Agency
(USE PA)-recommended hold times, apart from pH. Measurements for pH should be conducted within
15 minutes of sample collection; thus, the laboratory pH measurement will always be out of hold time.
' Based on the above review, the laboratory results are considered valid for the sampling event. Reported
concentrations are consistent with previous events, and the analytes that exceeded the Interim Narrative
Standard for this sampling event are listed by sampling location below:
1
Golder Associates Inc.
7245 W Alaska Drive,Suite 200,Lakewood,Colorado,USA 80226 T:[phone] F:[phone]
' Golder and the G logo are trademarks of Golder Associates Corporation golder.com