2017-02-10_INSPECTION - M2009062

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PERMIT#:M-2009-062 INSPECTOR'S INITIALS: ECS INSPECTION DATE: February 8,2017 OBSERVATIONS This was a monitoring inspection for the Weld County I I2c Pierce North sand and gravel operation conducted by Eric Scott of DRMS. This inspection was triggered by a citizen compliant received by DRMS on January 27, 2017. The complaint alleges that the pit is diverting and impounding surface water from the intermittent Lone Tree Creek, and thereby causing injury to downstream water rights. DRMS traveled to the site and met with Weld County representatives Clay Kimmi, Devon Traff, and Curtis Hall, and Division of Water Resources (DWR) District 1 Deputy Water Commissioner Jorge Vidal. The inspection commenced at approximately 9:40am and the weather was clear and windy. The site is located at the northwest corner of the intersection of Weld County roads 96 and 37. Weld County has permitted the entire '/ section at that location. The site identification sign was observed at the entrance, and the extent of the site was represented with berms and fences along the county roads at this time. Mining activity has taken place over most of the eastern portion of the site, and a diversion channel for Lone Tree Creek has been created immediately west of the excavated/stripped area as can be seen in the attached photos (Photo 2). The approximately 9.5 acre area excavated in the northeast area of the permit currently contains water as can be seen in the included inspection photos, as well as the attached Google Earth photo, dated 9/2016. The site was previously visited by DWR in response to a similar complaint in May of 2016. A memo dated May 23, 2016 detailing this visit was provided by DWR to DRMS during this inspection, and stated that the water in the North Pierce pit was believed to be groundwater, with a possible contribution from natural precipitation. No diversion or flow path from the Lone Tree Creek into the North Pierce Pit was noted during that investigation. It was reported to DRMS that during the summer/fall of 2016 the North Pierce Pit was partially pumped out by Weld County to further determine if the water in the pit was primarily groundwater, or surface runoff that had infiltrated through the sandy channel and banks of Lone Tree Creek into the lower elevation pit during spring runoff. Wood lath placed at the water line to mark the dropping water level as the pumping proceeded can been seen in photos 3 and 6. At the time of this inspection no surface water was present in the vicinity of the pit and no flow was present in Lone Tree Creek (photo 2). The water level in the pit has not yet returned to 2016 pre-pumping levels, however it has risen sufficiently since pumping stopped to submerge several of the lath markers (photo 3). Water was also observed to be surfacing and flowing into the pit in two places along the northeast and north sides of the pit (photos 4 and 5). As can be seen in the photos, the elevation of these active springs/seeps appears to be at or slightly below the previous high water elevation in the pit. These observations support the previous statement by DWR that the primary source of water in the existing pit is groundwater, not captured surface runoff. DRMS has identified the groundwater exposure at North Pierce Pit as a problem on the first page of this report. The approved permit for this site states that Weld County will operate this site as a dry pit and that mining activity will remain above groundwater. In addition, Weld County currently has no well permit, substitute water supply plan, or permanent augmentation plan from the State Engineer's Office (SEO) to authorize the exposure of groundwater. A corrective action due date of July 31, 2017 has been given at this time for Weld County to either dewater and backfill the pit sufficiently to eliminate groundwater exposure, or to properly permit the site through DRMS and SEO to allow mining to continue to expose groundwater. Page 2 of 4