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VII ~5 bridges; however, In the future some slope protection \.111 probably be found necessary downstream of the brl dg"s. As shown on Sheet JI, to protect the WestmlnHer Sewage Treatment Plant It will be necessary to improve the channel and construct a berm for flood-proofing structures. Slope protection for the lagoon berms had already been contemplated by Westmlnstelc and is shown On the Drawings. The Huron Street Bridge and the embankment must bE, raised to meet street overtopping criterIa. A raised foot path Is to be constructed through the bridge. The Bull Canal has constructed an embankment llcross Big Dry Creek and provided an overflow at a substantially higher elevation than the nor- mal stream bed elevation, and that Is not sufficient to pass the design flood of 10,800 cfs. As a result, the south bank of the built-up section of BIg Dry Creek will be an Island from 128th Avenue tel the overflow, and there are two different areas of flow to be consld..red. To prevent exces- s Ive, uncontrolled eros Ion below the overflow, a V"'shaped grass-lined chan,. nel should be constructed. Because I lability for maIntenance would shift from the owners of the Bul] Canal to Westminster, no modifications should be attempted to the embankment, even though conslde,rable erosional damage may occur to the Bull Canal diversion facIiltles. Hydraulic consequences of an embankment washout are rather Inconsequent lal. At ]28th Avenue, SOme flood-Inundated L9nd Is "rl!c]aimed" by construc- tion of an embankment to raise a driveway to meet the new road grades on 128th Avenue. A new bridge Is reconmended and some slope protection is required downstream. If the driveway emban~nent Is constructed at a lower e]evatlon, the flood plain would be defIned by the line for the "IOO-year Flood PlaIn Limit - Existing Channel Condition." If the embankmElnt Is mostly eliminated, then a spur dike should be constructed for thE' east side of the bridge. On Sheet 13 there Is a private bridge across 1~lg Dry Crl!ek ~{hlch Is overtopped and wll I probab I y be washed out vE'ry froequent I y. Because Its effect on the overall flood plain is slIght, WI! do not recommend replace- ment of this structure unless the prIvate owner chooses to del so at his own cos t. The BroomfIeld Sewage Treatment Plant shown 011 She,e! 14 Is not Inun- dated and requires no Improvements for protection. The 120th Avenue bridge needs to be replaced, and the Improved channel whil:h exists upstream of IJ. S. 287 should be extended downstream of U. S. 287 through the 120th Avenue bridge. ThIs results In a reduction Qf flood pLain in this Inter- section, and buIldings that would be flooded under the plcesent: hydrauklc ,;onstralnts wi I I not be flooded when the channel and bridge Improvements ~:I re made.