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PERMIT#: M-1974-086 <br /> INSPECTOR'S INITIALS: ECS <br /> INSPECTION DATE: April 22,2019 <br /> OBSERVATIONS <br /> This was a multi-agency inspection conducted by Eric Scott of the Division of Reclamation Mining and Safety(DRMS) and <br /> loana Comaniciu of the Colorado State Engineer's Office (SEO) Division of Water Resources of the Ralston Quarry. The <br /> Ralston Quarry is a 112c permit operated by Asphalt Paving Company(APC) in Jefferson County approximately 2.25 <br /> miles north of Golden and 0.6 miles east of Hwy 93. This inspection was intended to help address potential issues <br /> identified by DRMS and SEO during the approval process for AM04. AM04 is a MLRB-ordered amendment submitted to <br /> add acreage to incorporate into the permit area land that had been affected by a landslide in June of 2018. The <br /> operator has also added additional stockpile area to the SW area of the previous permit during this amendment. <br /> During the comment period for AM04,the SEO submitted a response to DRMS that raised concerns about potential <br /> ground water exposure at the site. These concerns were based on approximately 5.5 acres of existing standing water in <br /> the southeast area of the pit floor, and possible exposure of groundwater as mining progressed to the total proposed <br /> depth. <br /> Eric Scott and loana Comaniciu travelled together to the site and met with Stan Opperman of APC at the site office. Also <br /> present for this inspection were permitting consultant Ben Langenfeld, and Brierley Associates representatives Steven <br /> Kuehr and Rebecca Brock. Brierley Associates has previously conducted geologic characterization work at the site and <br /> was present to discuss technical details of the site characterization as needed. <br /> After signing in, DRMS and SEO accompanied APC personnel to the southeast area of the pit floor(photos 1-6). This <br /> area had previously been the location of approximately 5.5 acres of standing water. APC had asserted that this water <br /> was not intercepted groundwater, but storm water runoff that had collected overtime in the low point of the pit as <br /> there is no outlet for precipitation that falls into the pit area. To make this demonstration,APC has recently pumped the <br /> water from the pit into a series of settling ponds that discharge into the natural drainage located south of the permit <br /> area. APC then leveled the pit floor into a usable space and surfaced the area with crushed fines as can be seen in the <br /> attached photos. Due to the recent precipitation events (and rain during this inspection)there was a small area of water <br /> remaining in the far southeast corner of the pit (photo 6), but the remainder of the 5.5 acres of flooded pit floor had <br /> remained dry and no evidence of groundwater inflow was observed in the pit walls or floor. In the future,APC will need <br /> to pump any collected precipitation out of the pit to the natural drainage system within 72 hours. <br /> Although it does not appear that APC has intercepted groundwater at this time,there will need to be additional <br /> information provided to DRMS and SEO to demonstrate that groundwater will not be encountered at quantities beyond <br /> that allowed by the SEO lined reservoir standard as the mining progresses to the total proposed depth. <br /> If this demonstration cannot be made to the satisfaction of SEO,the permittee will need to provide a plan to monitor for <br /> possible groundwater interception as mining progresses, and provide a list of possible actions that may be taken by the <br /> permittee to maintain compliance with applicable regulations if groundwater is exposed in excess of the SEO lined <br /> reservoir criteria in the course of mining as currently approved. The approved post-mining land use for this pit is as a <br /> developed water resource (water storage reservoir) so meeting the lined reservoir standard will be a critical step in <br /> achieving this end use. <br /> DRMS will attach a condition to the approval of AM04 that will require the permittee to fully address this groundwater <br /> issue through submittal of a technical revision to the permit within 180 days from the approval date of the amendment. <br /> The condition will become an enforceable part of the approved amendment. <br /> Inspection Contact Address <br /> Stan Opperman <br /> Asphalt Paving Company <br /> 14802 W 44th Ave <br /> Golden,CO 80403 <br /> Page 2 of 3 <br />