CC PACKET 10131987 - Laserfiche WebLink

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� t • INTRODUCTION On Monday;._-August .1 7, 1987, under the commission of the City of St. Anthony, -Minnesota, this office conducted an inspection of a concrete inlet structure serving a runoff ,water detention basin. located within the City. The inlet facility has been damaged by the unusually heavy rains falling over the area' on July 23, - 1987. The object of the investigation was; ( 1 ) to assess the flood water damages, (2) to define the repairs that would be required to restore the facility to approximately the condition existing before the flood, and (3 ) to recommend the improvements that would make unlikely the redamaging of the facility under similar rain conditions. Our investigation was visual only. It is the opinion of this office that a soils investigation with soil borings should also be made before beginning repairs or modifications to the inlet. Such investigation will be necessary in the charting of the underground water flow at the inlet structure and in the design of a system to properly channel these flows to a suitable outlet. Structure plans of the inlet flume were available for this inspection. DESCRIPTION OF INLET STRUCTURE The inlet structure is a reinforced concrete U-shaped flume of about 10 foot width and 40 foot length. It was built in 1962. The flume '.s headwall, sidewalls, and tail cutoff wall are approximately vertical . The floor of the flume lies on a steep 1 . 4 to 1 slope. The tops of the flume sidewalls are sloped to approximately match the grade of the hill . into which the structure is founded, thus the sidewalls vary` in height. A 60" x 45"precast concrete arch. sewer feeds water into the flume at its • top. A debris-catch grating covers the pipe opening at the headwall . Energy dissipation blocks are built into the flume ' s floor at about six foot intervals.