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Rr_UL_4"V <br />OBSERVATIONS <br />PERMIT #: M- 2011 -028 <br />INSPECTOR'S INITIALS: KAP <br />INSPECTION DATE: February 26, 2014 <br />This inspection was conducted relative to a technical revision that was submitted by Four Corners Materials <br />(FCM), addressing storm water management issues. In addition to the operator, Matt Carnahan, also present <br />at this inspection were Matt Gavin, Dam Safety Engineer, Office of the State Engineer (SEO), and Jeff Titus, <br />District 30 Water Commissioner. <br />A major focus of this inspection was a berm that was constructed by FCM, designed to retain stormwater on <br />the north phase of the project site. The berm is approximately 35 feet wide at the base, 12 feet wide across <br />the top and up to 9 and one half feet tall at the tallest points. It runs along the west edge of the terrace, <br />situated above the drainage structures related to the spillway for the Animas -La Plata Project (ALP) dam. The <br />top of the berm is flat and is easily accessible by vehicle. Based on the visible material along the flanks of the <br />berm, it appears to be constructed of silty clay with a high content of large cobbles. A silt fence is installed <br />along part of the base on the west side of the berm. Mr. Carnahan also identified some waddles that FCM had <br />installed in the drainage leading down to the ALP structures to restrict the transport of sediments. Located <br />within the boundaries of the berm is a large basin that FCM installed to assist in containment of water within <br />the berm structure. <br />Tim Cazier, Division staff engineer, had contacted the SEO regarding this structure, questioning its <br />classification with regard to a jurisdictional dam. This question arose due to the containment capacity of 224 <br />acre -feet, and the height of the berm itself. After an assessment of the location, Mr. Gavin indicated that he <br />needed to do some calculations but stated he is not inclined to regulate this structure as a jurisdictional dam <br />because, although the capacity would categorize it as such, the precipitation history in this region results in <br />amounts that are a fraction of the amounts necessary to fill the containment structure. In fact, the technical <br />revision submittal indicates that it would take 36 consecutive 100 -year events to fill the structure with water. <br />Mr. Gavin indicated the he would send an e-mail to the Division conveying his opinion related to the structure. <br />Mr. Carnahan indicated that FCM may make some modifications to the berm structure but wanted the <br />Division to review and approve them prior to committing to the work. The Division requested that FCM <br />submit additional information related to the structure and proposed mining at the site, including: <br />1. Design specifications regarding how the berm was constructed, including depths of lifts, how they were <br />compacted and how they were keyed in. <br />2. Current dimension of the berm structure, including maximum height. <br />3. Proposed changes to the berm structure, including grading of the slope, final slope and final seeding plans. <br />4. Dimensions of the containment pond located within the bermed area. <br />5. The proposed mining plan for the south phase of the project, consisting of the area to the south of the <br />bermed portion, specifically addressing how storm water will be contained. <br />Page 2 of 4 <br />