2017-04-11_REPORT - M1977424 (2)

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Logan Wash Mine Annual Report Permit No. M-1977-424 2.3 Structures 2.3.1 Vaults, Pipelines, and Evaporation Pond Structures that remain at the mine site include two vault structures, one on the Lower Bench and one on the Research Mine Bench, one sealed ventilation shaft, and one capped and vented ventilation shaft. Pipelines include the retort water pipeline which conveys retort mine water from the sealed L-1 portal at the mine site to the Evaporation Pond; the Logan Wash Mine mine water drainage pipeline (LW -001) which extends from the sealed Ll portal to the Lower Bench Vault and then to an infiltration gallery on the Lower Bench; and the Research Mine mine water drainage pipeline (LW -002) which extends from the sealed Research Mine portal through the Research Mine Vault to the Lower Bench Vault and on to Lower Bench discharge point. See Figure 2 for the locations of these structures. The two bench vaults are administered as confined space concrete structures with surface access - ways constructed just above grade. Depending on the final mine closure method, these structures may remain as permanent structures on the mine site to manage and monitor mine water drainage. The retort water pipeline was constructed with manhole clean -outs approximately every 600 feet; two manholes, the Upper Manhole and Lower Manhole, are accessed periodically to measure retort water discharge rates. The Upper Manhole is located in the vicinity of the former Heater Treater (Area 15), in the upper part of Logan Wash near the confluence with Dry Gulch. The Lower Manhole is located immediately north of the Evaporation Pond, approximately 40 feet from the pond gate. Other manholes exist on the retort water pipeline that are buried by shallow road fill, colluvium, and vegetative litter, and have not been accessed in recent years. 2.3.2 Monitoring Wells Monitoring wells associated with the Logan Wash Mine were constructed within and outside of the immediate mine area. Past reconnaissance has been conducted to locate and confirm the existence of these well sites. Eight wells were located and identified within the mine area and within Logan Wash. Several other wells were located at some distance from the mine (see Figure 3 and Table 3). Of the 8 identified wells in the mine area, two wells, Well LWCW-IA and Well LW -22A, will remain in place as monitoring wells until final permit closure. Well LWCW-lA and LW -22A are sampled for water quality on a semi-annual basis. Wells LW -108, LW -112, and LW -242 were abandoned in 2005 in accordance with Colorado Division of Water Resources rules. The other 4 wells, LW -32, LW -45, and LW -116, remain in place in the case they may be of value in the evaluation of mine closure investigations. Casing access and downhole conditions are unknown for wells LW -32, LW -45, and LW -116. Reconnaissance to date has not revealed any other monitoring wells within the permit area and the Logan Wash drainage. Reconnaissance for wells located outside the permitted area in distant drainages was conducted in past reporting periods. Wells LW -102 and LW -243 were located in Smith Gulch, Well LW -103 was located in Kelly Gulch, and Well LW -104 was located in Riley Gulch. Well LW -121, apparently constructed in Bowdish Gulch, was not located after a thorough search and is assumed abandoned. Wells LW -102, LW -104 and LW -243 were abandoned in 2007. Table 3 shows the status of well abandonment as of this reporting period. Western Water & Land, Inc. 4