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Mr. Roger Schmidt <br /> March 15,2017 <br /> Page 4 <br /> between Al and the City/BIC, as well as a calculation sheet and specifications related to the 2006 <br /> project. <br /> WWE Comment: <br /> For clarification, the 2006 project referenced in the AI letter and in the attached <br /> correspondence is at the northeast end of the Al pit (see Figure in Appendix Q. This <br /> location is separated by roughly 1,800 feet from the location where the ditch failure <br /> occurred in 2010 and where the pipeline breaches occurred in 2013 and 2014. In <br /> addition, the Boyd-Freemen Ditch was relocated by Al to its current alignment sometime <br /> between 1999 and 2001 (based on aerial imagery), which was several years before the <br /> referenced 2006 project took place. <br /> Al letter,p. 2: <br /> The Al letter (p. 2, first paragraph) also states, "No other improvements throughout the rest of <br /> the relocated ditch were requested by the City/Boyd." <br /> WWE Comment: <br /> Only after the high flows in the Cache La Poudre River occurred in 2013 and 2014 was <br /> the insufficient erosion protection on the embankment of the Al gravel pit finally <br /> identified. These events demonstrated that the erosion protection on the Al Pit's western <br /> slope is not sufficient to protect the slope from major erosion when a flooding event <br /> causes shallow overland flow in the Cache La Poudre floodplain to flow down into the <br /> pit. <br /> Comments on the Tetra Tech Letter, dated January 11, 2017 <br /> Tetra Tech letter,P. 1, last paragraph, last sentence., <br /> "We agree that the increased flow velocities led to the erosion of the reclamation slope, hence <br /> the breach of the pipeline and erosion of the F-Street Agricultural Field." <br /> WWE comment: <br /> WWE and Tetra Tech are in agreement that the cause of the erosion of the reclamation <br /> slope is increased flow velocity. The eroding slope of the Al pit caused the breach of the <br /> pipeline and,in 2014,the erosion of the F Street Agricultural Field. <br /> Tetra Tech letter,p.2,second paragraph: <br /> The Tetra Tech letter raises questions about the suitability of the pipe selected for the inverted <br /> siphon application. The text states, "The actual pipe installed if not properly baclflled and joint <br />