2016-04-21_REVISION - M1977004 - Laserfiche WebLink

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Mr.Dustin Czapla Page 2 of 4 viable, will be used at strategic locations and are not intended to be long-term treatment systems. • Implementation of active management strategies to demonstrate that "treatment residuals" (particularly phosphate) can be controlled at the Sediment Pond, which will inform future full-scale BMP implementation plans. This letter is intended to provide DRMS sufficient information to determine whether the Phase 2 field activities planned for 2016 can be conducted under TR-6 or will require a separate technical revision to the Reclamation Permit. To support this determination, planned Phase 2 field activities are summarized below with a focus on drilling and potential surface disturbances. Additional details associated with the Phase 1 and 2 activities are provided in the 2015 Annual Reclamation Report. Prior to initiation of the Phase 2 field activities, approvals will also be obtained from the Water Quality Control Division as required by the CDPS permit and the United States Environmental Protection Agency for Class V aquifer remediation injection well"authorization by rule" in accordance with Title 40 Code of Federal Regulations (40 CFR) Sections 144.24 and 144.84(a). Piezometer Construction Up to four proposed piezometers, completed into waste rock, will be used to deliver, recirculate, and/or monitor phosphate and non-reactive tracer(s) near the toe of the Indian Rock Dump (Figure 2). The piezometers will be completed on a relatively flat portion of the Indian Rock Dump to an approximate depth of 60 to 90 feet. The estimated date of piezometer completion is in June 2016. Equipment used for the piezometer installation includes drilling equipment and support vehicles. Injection equipment will consist of tanks, plastic totes, flow meters, pumps and conveyance piping necessary to transport the injection fluid to the piezometers. The new piezometers will be constructed in accordance with Colorado Office of the State Engineer guidelines (Colorado OSE 2005). Piezometers will be constructed with 4-inch schedule 40 PVC casing and screen. The screen will have a slot size of 0.020 inches and lengths will be approximately 20 feet. A silica 20/40 sand will be used as a screen filter pack. Piezometer casing will be grouted in place using a hydrated bentonite seal above the screen and a cement and bentonite mixture grout. The surface stick-up well completion will consist of a 7-to 10-inch steel vault and locking lid. The inner PVC casing will be sealed with a locking cap. The well vault will be surrounded by an approximate 4- foot diameter concrete apron sloped to facilitate proper drainage. Piezometer Plugging and Abandonment The proposed piezometers will be used as part of the long-term monitoring program associated with the pilot test and full-scale implementation. When warranted, the piezometers will be abandoned in accordance with Rule 16 of the Colorado Water Well Construction Rules. 460 West 5o North,Suite 500,Salt Lake City,Utah 84101 TEL:(801)990-3547