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PERMIT#: M-1977-300 <br /> INSPECTOR'S INITIALS: AME <br /> INSPECTION DATE: August 4,2020 <br /> OBSERVATIONS <br /> This inspection of the Schwartzwalder Mine (Permit No. M-1977-300) was conducted by Amy Eschberger and <br /> Tim Cazier of the Division of Reclamation, Mining and Safety(Division). The operator was represented by <br /> Billy Ray and Sam Lowe during the inspection. The site is located approximately 6 miles northwest from <br /> Golden, CO in Jefferson County. Access to the site is off Glencoe Valley Road. This site is on a quarterly <br /> inspection frequency. This inspection serves as the 3rd quarter inspection for 2020. However, the Division <br /> anticipates an additional inspection will be conducted this quarter in association with the North Waste Rock Pile <br /> (NWRP) diversion channel project (discussed below). Photos 1-13 taken during the inspection are included <br /> with this report. <br /> The primary purpose of this inspection was to review the Phase 1 construction work completed for the NWRP <br /> diversion channel project approved under Technical Revision No. 28 (TR-28; approved on March 27, 2020). <br /> Because the NWRP is considered an Environmental Protection Facility, per Rule 7.3.1(1), construction work <br /> shall be done in phases, and no construction work shall begin on any subsequent phases of the facility without <br /> first obtaining Division acceptance. Phase 1 of this project included constructing the water capture structure <br /> concrete seal trench into bedrock in the ephemeral drainage above the NWRP. Based on the test pit which was <br /> dug in this area back in August of 2019, it was thought that bedrock would be located approximately 4 feet <br /> below grade. However, what was initially thought to be bedrock was later found to be a large boulder. <br /> Additional excavation work that occurred after TR-28 approval determined the depth of bedrock to be <br /> approximately 4-5 feet deeper than the design depth. Therefore, the trench was dug approximately 8-9 feet <br /> below grade. The operator has significantly over-excavated the seal wall trench and has rebar tie-ins epoxied <br /> into the bedrock. Additional rebar will be installed higher up in the trench prior to placing the concrete. The <br /> sidewalls of the trench appeared to be composed of fairly competent bedrock overall with portions of weather( <br /> bedrock along the lateral (northwestern and southeastern) sidewalls. The Division believes the over-excavation <br /> of the trench will significantly limit the potential for seepage to occur through the weathered bedrock. It should <br /> be noted, the material excavated from the trench which was being temporarily stockpiled on top of the NWRP <br /> during the Division's last inspection (on June 26, 2020)has been placed in the CV Glory Hole. <br /> Subsequent to the inspection, informal discussions with the operator(via email and telephone) clarified the <br /> intent to complete the seal wall in two separate concrete pours. Two pours were deemed necessary due to the <br /> larger volume of concrete required to fill the deeper excavation. The post-inspection discussions focused on the <br /> method to be selected to ensure a watertight seal between the two pours. Discussions were continuing when this <br /> report was completed. Any deviations from the approved design will be incorporated into the final as-built <br /> construction drawings to be submitted to the Division after the project is completed. The Division approves the <br /> Phase 1 construction work completed for the NWRP diversion channel project, and hereby authorizes the <br /> operator to proceed with the next construction phase The next inspection must be scheduled after the channel <br /> subgrade is completed and during installation of the Geoweb components, preferably while the manufacturer <br /> representative is present on site. <br /> The Division observed the "seep areas"near the toe of the NWRP (between Glencoe Valley Road and Ralston <br /> Creek), and found these areas to be dry. The creek was flowing above the upgradient cutoff wall and these <br /> flows were being routed through the bypass pipeline. The water treatment plant was online during the <br /> inspection. The mine pool was at 206 feet below the Steve Level, which is 56 feet below the required 150 foot <br /> depth. The operator has plans to dewater the mine pool further during the operating season in 2020 to enable a <br /> 6-month shutdown of the plant (anticipated for November 2020 to May 2021). The operator will monitor the <br /> recharge response from these seasonal pumping and shutdown periods. The last in-situ injection treatment of the <br /> mine pool was completed in the I'quarter of 2020, which included two tracers. The operator is currently <br /> monitoring the effect of this in-situ treatment on the chemistry of the mine pool as they dewater and treat the <br /> Page 2 of 10 <br />