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Mr.Roger Schmidt <br /> March 15,2017 <br /> Page 5 <br /> restrained would be susceptible to leakage at the joints that can lead to erosion around the pipe <br /> and subsequent settlement above the pipe." <br /> WWE Comments: <br /> • The amount of water pressure in the inverted siphon pipe section in question is <br /> approximately 4 to 5 pounds per square inch (psi). The 48-inch diameter <br /> DuroMaxx pipe used for the project (manufactured by ConTech) is made from <br /> steel-reinforced high density polyethylene (HDPE) and is rated to withstand up to <br /> 8.5 pounds per square inch continuously for 50 years and up to 12.0 psi for 9 <br /> months. The High Performance bell and spigot connection with gasket is rated to <br /> 15 psi. Consequently, both the pipe and the pipe connections are rated to <br /> withstand the pressures that would have been observed within the pipeline. <br /> • Anderson Consulting Engineers, Inc. (Anderson) is recognized to be a well- <br /> established, competent and experienced engineering firm. A discussion with Scott <br /> Parker, P.E., the Anderson design engineer, found that the construction of the <br /> pipeline, including the pipe connections, went well and that a representative from <br /> the pipe manufacturer also came to the project site during installation of the pipe. <br /> Thrust blocks were not identified as necessary for the pipeline configuration. <br /> • Roger Schmidt, BIC President, who is responsible for maintaining and operating <br /> the pipeline, was interviewed and stated there was no known evidence of leakage <br /> from the pipe, nor was there any indication of settlement above the pipe,between <br /> the time the pipeline was installed in 2012 until the time that the pipeline was first <br /> breached by erosion in 2013. It was also stated that during the periods of time <br /> when the pipeline had water flowing in it, City employees were inspecting <br /> conditions along the pipeline at least two times per day. In addition, there are no <br /> known reports of Al contacting BIC to identify leakage from the BIC pipeline into <br /> the AI pit. <br /> • Photos taken by Roger Schmidt, BIC President, on May 27, 2014 during the early <br /> stages of the 2014 flood event, show a broad sheet of flow reaching the top of the <br /> pit's embankment and starting to flow down into the pit (see photos in Appendix <br /> B to this letter). The photos do not show a distinct location with settlement in the <br /> pipeline that caused flows to concentrate down the embankment. <br /> • Although there is no indication that the pipeline was leaking, if leakage had <br /> occurred, the native material in the area of the pipeline has high hydraulic <br /> conductivity(in accordance with the geotechnical engineering analysis for the site <br /> conducted by Olsson and Associates in October 2014 for pipe repairs,the material <br /> is generally sand with gravel and cobbles, overlying shale bedrock). Leakage <br />