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Creation Date: Revision Date: CC 02/28/2003 2/19/2020 4**,�G Control Number PUE.EN.D.026.04 Pa e:5 of 30 Title: Sampling and Analysis Plan for Environmental Groundwater Monitoring 1.0 INTRODUCTION AND SAMPLING OBJECTIVES This Sampling and Analysis Plan (SAP) provides a protocol for performance of shallow groundwater monitoring at the GCC Rio Grande, Inc. facility in Pueblo, Colorado (the Site). Based on increased knowledge of the groundwater system at the Site, groundwater monitoring locations and requirements have evolved significantly since the previous SAP was prepared in 2003 (Brown and Caldwell,2003).As a result of subsequent findings, and in accordance with Technical Revision No.3 (TR-03)approved by the Colorado Division of Reclamation,Mining and Safety(DRMS) in April 2013, all shallow wells subject to prior monitoring were plugged and abandoned except for one(MW-005,hereinafter referred to as MW-5). The plugged wells were either dry,or were located far from the site along the St.Charles River and proven to not be applicable for GCC monitoring. MW-5, located north of the plant, has remained dry since it was installed so no samples have been collected.Pursuant to TR-06, approved by DRMS in July 2017,new wells MW-6 and MW-7 were installed in December 2017 downgradient of the second mine panel (Figure 1). This SAP describes groundwater sampling and analysis procedures for obtaining chemical data from existing wells, and future wells installed as mining progresses, to define the baseline groundwater conditions and track any changes in applicable water quality constituents in potentially affected groundwater. Significant changes to the sampling protocol(s) will be submitted to DRMS for approval prior to implementation. The following sections provide details of the SAP, including sample locations and frequency, sampling methods, laboratory analysis, quality assurance/quality control (QA/QC), and reporting. 2.0 GROUNDWATER SAMPLING LOCATIONS AND FREQUENCY Figure 1 illustrates the site features and mine plan. GCC quarries the Fort Hayes Limestone Member of the Niobrara Formation, and began extraction and processing in 2007 and 2008, respectively. GCC is permitted to quarry the Fort Hayes Limestone and approximately 5 feet into the Codell Sandstone, which has also been described as hard, brown sandy petroliferous limestone and a platy and shaly sandstone. Figure 2 shows a site stratigraphic section. Site drilling logs indicate that the Codell also contains multiple shale or sandy shale lenses.Initially, GCC planned to remove and process Codell Sandstone,but that was eliminated near the onset of operations when further testing determined the material was not beneficial to process.GCC extracts only the Fort Hayes, leaving the bottom one foot of the limestone. Regionally,the Juana Lopez Shale Member separates the Fort Hayes and Codell members,but is only about 2 feet thick. Locally, the Juana Lopez Member is largely absent due to an erosional unconformity, such that the Fort Hayes directly overlies the Codell (Collum, 2000). Underlying the Codell is approximately 400 feet of upper Cretaceous members, principally composed of dense shales, which provides an effective hydraulic barrier from the underlying Dakota Sandstone aquifer.