2918-25 STORMWATER final 4_1_25.doc.pdf

32 iv. The trash rack shall be constructed of rigid, durable, and corrosion resistant material and designed to withstand a perpendicular live loading of 300 pounds per square foot. 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: i. The overflow grate shall be secured to the outlet structure but removable for emergencies and maintenance. ii. The overflow grate spacing shall be no greater than two inches across the smallest dimension iii. 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 300 pounds per square foot. 3. Stormwater management BMPs shall include escape provisions as follows: i. If a stormwater management BMP has an outlet structure, escape provisions shall be incorporated in or on the structure. Escape provisions include the installation of permanent ladders, steps, rungs, or other features that provide easily accessible means of egress from stormwater management BMPs. With the prior approval of the municipality pursuant to § 25-29.8C, a free-standing outlet structure may be exempted from this requirement; ii. Safety ledges shall be constructed on the slopes of all new stormwater management BMPs having a permanent pool of water deeper than two and one-half feet. Safety ledges shall be comprised of two steps. Each step shall be four to six feet in width. One step shall be located approximately two and one-half feet below the permanent water surface, and the second step shall be located one to one and one-half feet above the permanent water surface. See § 25-29.8E for an illustration of safety ledges in a stormwater management BMP; and iii. In new stormwater management BMPs, the maximum interior slope for an earthen dam, embankment, or berm shall not be steeper than three horizontals to one vertical. D. Variance or Exemption from Safety Standard A variance or exemption from the safety standards for stormwater management BMPs may be granted only upon a written finding by the municipality that the variance or exemption will not constitute a threat to public safety. E. Safety Ledge Illustration Elevation View –Basin Safety Ledge Configuration