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<br />.'.. <br /> <br />Department of the Army <br />February 14, 1980 <br />Page Two <br /> <br />become a d'irect outgrowth of those omissions. In short, the <br />structure ~Ias not designed to work suitably with the site <br />instead whilt followed was an exercise to modify the site <br />to the wod: appropri ate1y with the structure. <br /> <br />The developer approached the Town's planning and engineering staffs with the <br />following proposal. <br /> <br />1. As a result of the excessive width of the office building, <br />a fill operation would be required along the west perimeter <br />of the Blue River bank. The existing bank lay at a repose <br />of approximately 3 to 1 and the fill would alter the bank <br />to a 1 1/2: 1 slope. The fill would be placed and compacted <br />in small lifts, to provide a sufficient, building pad and <br />sound, structural subgrade. <br /> <br />2. The Town expressed concern over the steep 1 1/2: 1 banks and <br />instructed the project engineer to devise a plan to stabilize <br />the fill slope, reinforce and define the Blue River Channel <br />and upgrade the existing sway-back channel to handle the <br />capacities and flows anticiapted fo.. the 100-year flood <br />event. The possibility of constructing gabion structures <br />along that portion of channel was introduced by the Town. <br /> <br />3. Robillard & Associates, the consulting civil engineers <br />retained by Sawmill Associates submitted detailed <br />excavation alnd grading plans to the Town on May 17, 1979. <br />Our staff relviewed cross-sectional studies as well as the <br />accompanying hydraulic calculations submitted by Robillard <br />& Associates. Our prime concerns were: <br />, <br /> <br />1. To maintain the integrity of the Blue <br />River f100dway and to equal or better the <br />altered channel. <br /> <br />2. Integrate all bridge and channel work with <br />data proj ected in the updated 1979 Brecken- <br />ridge Flood Plain Study. <br /> <br />3. To .reinforce both channel and fill areas with <br />soml~ heavy structure to prevent erosion and <br />denne the perimeter of the new channel. <br /> <br />These concerns were satisf'ied in the Robillard proposal. Large boulders and rip- <br />rap would be imported and placed to reinforce the channel perimeter and the hy- <br />draulic calculations confirmed that a new trapezoidal channel as per plans would <br />provide equal capacity for the 100-year storm event. <br />