Public Township Council Meeting — Packet

DRAFT PROPOSED REVISIONS – OCTOBER 2011 b. The provisions of this subsection are not intended to preempt more stringent municipal or County safety requirements for new or existing stormwater management basins. c. Requirements for Trash Racks, Overflow Grates and Escape Provisions. 1. A trash rack is a device designed to catch trash and debris and prevent the clogging of outlet structures. Trash racks shall be installed at the intake to the outlet from the stormwater management basin to ensure proper functioning of the basin outlets in accordance with the following: (a) The trash rack shall have parallel bars, with no greater than six (6) inch spacing between the bars. (b) The trash rack shall be designed so as not to adversely affect the hydraulic performance of the outlet pipe or structure. (c) The average velocity of flow through a clean trash rack is not to exceed two and one-half (2.5) feet per second under the full range of stage and discharge. Velocity is to be computed on the basis of the net area of opening through the rack. (d) The trash rack shall be constructed and installed to be rigid, durable, and corrosion resistant, and shall be designed to withstand a perpendicular live loading of three hundred (300) lbs./ft. sq. 2. An overflow grate is designed to prevent obstruction of the overflow structure. If an outlet structure has an overflow grate, such grate shall meet the following requirements: (a) The overflow grate shall be secured to the outlet structure but removable for emergencies and maintenance. (b) The overflow grate spacing shall be no less than two (2) inches across the smallest dimension. (c) The overflow grate shall be constructed and installed to be rigid, durable, and corrosion resistant, and shall be designed to withstand a perpendicular live loading of three hundred (300) lbs./ft. sq. 3. For purposes of this subsection, escape provisions means the permanent installation of ladders, steps, rungs, or other features that provide easily accessible means of egress from stormwater management basins.

on, escape provisions means the permanent installation of ladders, steps, rungs, or other features that provide easily accessible means of egress from stormwater management basins. Stormwater management basins shall include escape provisions as follows: (a) If a stormwater management basin has an outlet structure, escape provisions shall be incorporated in or on the structure. With the prior approval of the reviewing agency identified in subsection 25-29.8d. a freestanding outlet structure may be exempted from this requirement. (b) Safety ledges shall be constructed on the slopes of all new stormwater management basins having a permanent pool of water deeper than two and one-half (2 1/2) feet. Such safety ledges shall be comprised of two (2) steps. Each step shall be four (4) to six (6) feet in width. One (1) step shall be located approximately two and one-half (2 1/2) feet below the permanent water surface, and the second step shall be located one (1) to one and one-half (1 1/2) feet above the permanent water surface. See subsection 25-29.8e. for an illustration of safety ledges in a stormwater management basin. (c) In new stormwater management basins, the maximum interior slope for an earthen dam, embankment, or berm shall not be steeper than 3 horizontal to 1 vertical. d. Variance or Exemption from Safety Standards. 171