28-14 Amend Chp. 1339 Storm Water Mgmt

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operated in a safe and convenient manner. During the annual inspec- tions the valves shall be fully opened and closed at least once, and the certifying official shall attest to this on the inspection form. To prevent vandalism, the handwheel shall be chained to a ringbolt or manhole step. (5) Principal Spillway: Each principal spillway shall be designed in ac- cordance with the NRCS standards and specifications for the office serving the county. Each principal spillway shall have the capacity to pass the 100 -year design storm flow. The inlet or riser size for the pipe drops shall be designed so that the flow through the structure goes from weir flow control to pipe flow control without going into orifice control in the riser. The crest elevation of the primary spillway shall be no less than one foot below the emergency spillway crest. Premium joint pipe is required and a removable trash rack shall be installed at each loca- tion. Anti -seep collars shall be provided for all pipe conduits through an embankment. (6) Emergency Spillway: An emergency spillway shall be provided on each storm water management basin. Emergency spillways shall con- vey flood flows safely past the embankment, and shall be designed in accordance with NRCS standards and specifications for the office serv- ing the local county. Emergency spillways shall have a 100 -year design storm capacity unless exempted in writing by the city engineer. (7) Embankments: Each dam embankment shall be designed in accordance with the NRCS standards and specifications for the office serving the county that the project is located in. Anti -seep collars shall be provided for all pipe conduits through an embankment. (8) Safety Features: A. The primary spillway opening shall not permit access to the public and other non - maintenance personnel. B. The perimeter of all water pool areas that are deeper than three feet shall be surrounded by benches that meet the following: i. A safety bench, with a maximum slope of 3 percent, which ex- tends outward, on dry land, from the shoreline. This bench will be a minimum of 25 feet wide to provide for the safety of individuals and maintenance vehicles that are adjacent to the water pool. The safety bench may be landscaped, without the use of structures, to prevent access to the water pool. ii. Side slopes between the safety bench and the aquatic bench shall not be steeper than 3:1 (three feet horizontal for every one foot vertical). iii. An aquatic bench that extends inward from the shoreline far enough to ensure public safety and has a maximum depth of 15 inches below the normal water surface elevations. The aquatic bench may be landscaped to prevent access to the deeper water pool. 50