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<br />Review of Engineering Principles Employed to Support the Durango Boating Park <br />Recreational In-Channel Diversion Application <br /> <br />Don R. May, PE, Ph.D <br />September 3, 2007 <br /> <br /> <br />~~ <br />q ~/ ~D <br />___- \ \" . G <br />(}f <br /> <br />Topics addressed in this review include: <br />a. 1 aO-year flood conditions <br />b. Impact on Animas LaPlata Project (ALP) intake structure <br />c. River hydraulics <br />d. H1EC-RAS modeling <br />e. Power indices <br />f. Similarity modeling, stability, and morphology <br />g. Engineering design <br />h. River basin hydrology Q \.- <br />i. Hydraulic jumps--b--tJ-'c <br />j. Weir flow model ;oJ. <br /> <br />This report provides a review of the principles employed by Recreation Engineering a~d Planning, Inc. <br />(REP) of Boulder, Colorado in two reports prepared for the City of Durango as part of/its' application <br />for a Recreational In-Channel Diversion (RICO) associated with the proposed Duran~o Boating Park. <br />(DBP) TI1~goal of this review is to assess the engineering validity of basic principle~, statements and <br />../ conclusiorYmade in these reports. The reports are titled: 1) Detail Design Report For The Durango <br />Boating Park, September 1, 2006, 2) Report Of The Design, Functionality, and Physical <br />CharactE~ristics of the Durango Boating Park As It Relates To The RICO Application, September 8, <br />2006. <br /> <br />Report 1. <br />Note: Several figures in this report are either not properly labeled or are not readable making it <br />difficult or impossible to accurately evaluate the author's comments. -.J <br /> <br />1. Baseline, 100 yr flood conditions: <br />(p. 4) - existing conditions from recent river survey were used to create a model in HEC-RAS. <br />Model was compared to rough flood mapping that exists ... and found to be relatively <br />accurate... ~ ~ ~Q. <br />It is not clear what is meant by "rough flood m.{pping that exists'" There should be verification <br />or validation that the REP existing conditionJ~atch. the officially accepted flood plain. <br /> <br />(p.5, par. 1) No evidence is provided in the report to substantiate the claim that there is no <br />negative impact. Figure 1 and Appendix 2 are unreadable. There is no quantification of the <br />"closeness of match". .~ <br /> <br />2. Impact on Animas LaPlata Project (ALP iZ'structure: <br />(pp.5-7) Th ~n this report, w' out clarification, does not substantiate the claim that <br />the proposed R has no impact on he ALP intake structure. First, the figures discussed are <br />virtually unreada _~ making detaile evaluation difficult if not impossible. Next, it is claimed <br />that the computed water surface evations (HEC-RAS), in the vicinity of the intake structure, <br />derived from the pre and post ect conditions are identical ang henc~ there is no impact. <br />The water surface profiles computed using this model are directly depel'ldent on parameters <br />that are set by the user to initiate and run the model. The question of upstream or downstream <br />Gontrol is an example of a critical user input. No details are provided a'2,9 henc~ the claim <br />cannot be substantiated. --J <br />