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<br />
<br />FIGURE 5. - View of 15th Street Bridge in downtown Denver, shortly after its collapse. Center-support pier was
<br />undercut by scour. Denver Post photograph by John Prieto, May 6, 1973.
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<br />backed up sewers in many places, and extin-
<br />guished pilot lights and shorted out home fur-
<br />naces, With these effects in mind, crews from
<br />the Denver Street, Highways, and Fire Depart-
<br />ments worked throughout the hours of peak
<br />flooding to keep bridges across the South Platte
<br />free of floating debris (The Denver Post, May
<br />7, 1973), Their actions probably saved many
<br />bridges from damage or destruction and dimin-
<br />ished the severity of flooding along the banks,
<br />West of the city, scour was severe on such
<br />tributary streams as Coal Creek, Ralston Creek,
<br />Big Dry Creek, Leyden Creek, Van Bibber
<br />Creek, Lena Gulch, McIntyre Gulch, Weir Gulch,
<br />Mount Vernon Creek, Bear Creek, Turkey
<br />Creek, North Turkey Creek, Deer Creek, and
<br />Massey Draw (figs. 6, 7). Much of the damage
<br />caused by these streams resulted from scour,
<br />undermining, blockage of culverts, and conse-
<br />quent inundation. Massey Draw did extensive
<br />damage at Chatfield Dam, on the Jefferson
<br />County side, when it broke out of an artificial
<br />channel and badly scoured engineered slopes
<br />and embankments (Edward E. McGregor, writ-
<br />ten commun" 1973). Damage at Chatfield Dam
<br />totaled many thousands of dollars.
<br />
<br />Roads, embankments, and bridges in the
<br />mountains were badly damaged by scour, pri-
<br />marily by overtopping and undercutting at
<br />places where channels were constricted by road
<br />embankments. Scour of this sort along Turkey
<br />Creek, North Turkey Creek, and Deer Creek
<br />caused the largest losses in Jefferson County.
<br />To the south, in Douglas County, scour dam-
<br />age was extensive at West Creek, West Plum
<br />Creek, Happy Canyon Creek, Sellers Gulch
<br />south of Castle Rock, Cherry Creek, West
<br />Cherry Creek, Willow Creek at State Highway
<br />470, Indian Creek, and several other small
<br />gulches (John 0, Maberry, written commun"
<br />1973). Specifically, the following scour effects
<br />were noted by Maberry:
<br />West Creek damaged and closed State High-
<br />way 67 between Deckers and Woodland Park to
<br />the south; two small reservoirs failed in se-
<br />quence, the upstream one first, by overtopping,
<br />thereby swamping the lower dam and creating
<br />a "wall" of water that destroyed much of the
<br />highway and several mountain homes (fig. 8),
<br />West Plum Creek washed out bridges at Se-
<br />dalia and at Jackson Creek Road, It washed out
<br />culverts, dips, and weirs for irrigation ditches,
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<br />8
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