2018-03-09_ENFORCEMENT - M2004031

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E 91T WO04-031 INSPECTOR'S INITIALS:JLE INSPECTION DATE:November 8,2017 It should be noted that a reservoir outlet pipe system must be installed on the north side of the reservoir to ' convey Orr Drain flows and release some flood waters when the reservoir is operating at the normal high water surface elevation. As of the date of the inspection, these outlet pipes have not been installed. Prior to when the reservoir becomes operational, the Operator must install these reservoir pipes. Mr. Refer indicated ' that Aggregate Industries was having difficulty working with the City of Thornton who now owns the reservoir and Denver Water the entity that owns land to the north to obtain an easement to install the reservoir pipes. While the Division sympathizes with these challenges, in order for the Permanent Plan to function as designed when the reservoir is in operation, the Operator must install these outlets pipes. Availability Of Records: ' A review of the Operator's annual reports from the site was conducted. Part of the Operator's approved plan is to monitor groundwater monitoring wells HZMW-2, 11A and 11B adjacent to Mr. Orr's property. Also the Operator committed to monitoring existing staff gauges installed on site. Monitoring of these devices is supposed to occur monthly. Upon review of the Operator's annual report for 2017, monitoring well HZMW-2 was noted to be "unaccessible" on October 11, 2016 and no additional data was submitted for the rest of the reporting year (September 27, 2016 to September 27, 2017). Near HZMW-2, the Operator is monitoring a ' staff gauge, SG-2. During the 2017 reporting year, for SG-2, between January 2017 through July of 2017, no monitoring data was provided in the annual report. Wells HZMW-11a and 11b were measured monthly for groundwater elevations for the reporting year for 2017. ' Based on the available data the groundwater level reported for monitoring wells HZMW-2 11a and 11b it g p g , does not appear groundwater levels have dropped below the maximum groundwater elevation reported for the area prior to the completion of the slurry wall. It does not appear the Operator has lowered the groundwater level at the site either temporarily or permanently. iHydrologic Balance: Based on the observations made during the inspection,the Orr property is still flooded and the Operator has failed to mitigate the disturbances to the prevailing hydrologic balance in accordance with the Board's order. The Operator is not allowing the Orr Drain to function when the Orr Drain gate is closed which prevents the drawdown of the groundwater. In addition,the Division believes surface water is a significant source of the ' water flooding Mr. Orr's property because the Bull Seep is not sufficiently conveying the surface water around the Orr property. This issue is cited as a problem at the beginning of this report. The Operator must mitigate this issue in the time specified by the Division or enforcement action will be taken. ' Page 4 of 11