2017-04-14_REPORT - M1977004 - Laserfiche WebLink

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Pitch Reclamation Project Colorado Mined Land Reclamation Board — 2016 Annual Reclamation Report achievable for Indian Creek, which is the underlying uranium site-specific standard. Following expiration of the Temporary Modification on June 31,2015,the underlying site-specific narrative standard of LPL applied, which has the potential to be specifically quantified by the Commission based on the HMC technical evaluations. In response to these regulatory changes, HMC initiated technical evaluations to support development of the LPL-based narrative standard on Indian Creek.An integral component to establishing a reasonable and defensible LPL is development of BMPs for uranium load reduction. Work performed since 2013 has established a fundamental understanding of surface water and groundwater flow and geochemical conditions at the Pitch Reclamation Project. Specifically: • An initial conceptual site model (CSM)was developed to provide an understanding of the natural and anthropogenic sources of uranium at the Pitch Reclamation Project as well as the geochemical processes that control uranium concentrations in surface water and groundwater. A summary of the CSM was provided to the WQCD in August 2014. • With the CSM established in 2014 an alternatives evaluation was performed to assess viable clean water diversion, uranium source control, in-situ, and passive/semi-passive options to achieve uranium mass load reduction and establish the LPL for uranium at SW-33. • "Proof of concept" bench testing performed in 2014 demonstrated that addition of phosphate(as pH-neutralized phosphoric acid)to the Pitch Reclamation Project surface water and groundwater resulted in rapid and near complete immobilization of uranium. As a result, phosphate-based treatment was identified as a primary means of achieving source control in the underground mine workings and North Pit Lake. • In 2015, initial field-scale pilot testing of in-situ source treatability in the underground workings via phosphate injection was implemented to investigate the viability of full-scale treatment at the high elevation mine site with limited year-round access. • In 2016, the field-scale pilot testing activities were expanded to include larger-scale phosphate injections in the underground workings, injection pilot testing in the Indian Rock Dump, and testing of solid-phase reactive media for achieving dissolved uranium removal in a downstream ETC approach (Photographs 26 through 30). The knowledge gained from pre-design pilot-testing and associated monitoring,conducted during the 2015 and 2016 field seasons,will be used to design, permit,and implement load reduction/treatment approaches to establish the LPL for uranium. 28