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Interoffice Memorandum <br />To: Rob Zuber <br />From: Zach Trujillo <br />Subject: Colowyo — First, Second and Third 2014 West Pit Fill Monitoring Report <br />Date: 10/24/2014 <br />i.• <br />After my review of the — First, Second and Third Quarter West Pit Fill Monitoring Report for the year 2014, 1 find the <br />report in compliance with the following rules: <br />1. 4.09.1(11)(a) —The fill was inspected for stability by a registered engineer during the placement and compaction <br />of fill materials. <br />2. 4.09.1(11)(b) —The qualified registered engineer provided to the Division a certified report within two weeks <br />after the inspection that the fill is being constructed as specified in the design approved by the Division. The <br />West Taylor Fill was inspected on March 19 (1St quarter), June 24 (2nd quarter) and September 17, (3rd quarter) <br />2014 and the Quarterly Fill Monitoring Report was received by the Division on April 17 (1St quarter), July 11 (2nd <br />quarter) and October 7 (3rd quarter) 2014. No appearances of instability, structural weakness, and other <br />hazardous conditions were noted in any of the inspection reports. <br />3. 4.09.1(11)(c) — Rule 4.09(11)(c) is no longer applicable during this stage of fill construction. <br />During the 1St quarter inspection report, it was noted that the largest displacement of 0.167 ft. occurred at the 7250' <br />(elevation) West prism. When inspecting the prism, it was observed that this prism was damaged. Colowyo stated that <br />the large displacement was most likely due to this prism being damaged while all other prisms are on average, deviating <br />less than 0.093 ft. The 7250' West prism was replaced and 2nd quarter readings and according to Colowyo, confirmed <br />that the damaged prism caused the large displacement. When comparing 1St and 2nd quarter readings at the 7250' West <br />prism, the difference in readings is 0.028'. This displacement appears to be about average with general displacement <br />readings and I would agree with Colowyo's assessment that the damaged prism was the reason behind the large <br />displacement reading from the 1St quarter. <br />During the 3rd quarter West Pit Fill report, it was noted that the 7250' West prism was missing and so no displacement <br />readings were recorded for this elevation. Currently, it appears Colowyo is only reporting the single largest displacement <br />at any point on the pit fill along with the average deviation. With no available data for 7250' West prism, Colowyo <br />instead reported the readings at 6950' East monument. However, little to no displacements has been recently recorded <br />for the 6950' East monument in Colowyo's reports. With no additional readings from other points along the fill, the <br />Division has no way to compare information at this monument. In the event of future damaged or missing prisms, it <br />would be recommended that Colowyo reports more than one displacement. This will allow the Division to more <br />accurately review Colowyo's pit fill inspection reports for any potential stability issues in the event a prism goes missing <br />or is damaged. At this time, there are no issues or stability concerns with the West Pit Fill. <br />