Erosion and sediment control plans shall utilize the following best management practices, and shall conform to the provisions of the Stormwater Manual, to minimize erosion and control sedimentation. Any best management practices may be selected provided that they are, at a minimum, as protective as Kentucky’s General Permit for Stormwater Construction Sites (KYR10).
(a) Nonstructural best management practices. The following nonstructural practices shall be incorporated into all erosion and sediment control plans.
(1) Avoidance of the floodplain.
a. Temporary sediment control in a permanent pond shall be allowed in the post-development floodplain, but not in the stream.
b. Roadways and utilities may only cross the floodplain at angles within ten (10) degrees of perpendicular to the water.
c. In order to protect floodplains, streams and watercourses during grading, stripping, excavating, filling or other disturbance of the natural ground cover, a vegetative buffer strip of twenty-five (25) feet, measured horizontally from the edge of the stream bank, shall be provided on each side of the stream, or in absence of clear stream banks, twenty-five (25) feet, measured horizontally from the centerline of the stream. Within the vegetative buffer strip, there shall be no grading, filling, removal of vegetation, or other disturbance of the natural ground cover or natural features. The buffer shall be expanded to 50 feet in areas where the receiving waters have been designated as Coldwater Aquatic Habitat or Outstanding State Resource Water, categorized as an Outstanding National Resource Water or Exceptional Water, or has been listed in the most recently approved Integrated Water Quality 305(b) Report to Congress as an Impaired Water (sediment impaired) for which an approved TMDL has not been developed for pollutants of concern that may be discharged from the facility in accordance with the KYR10 permit.
(2) Construction of on-site measures prior to soil disturbance. All on-site measures required by the erosion and sediment control plan shall be made functional prior to commencing soil disturbance on the site. Clearing, except as is necessary to establish such on-site measures, shall not begin until all on-site measures have been installed.
(3) Reduced exposure time. Permanent and temporary soil stabilization, as provided in the Stormwater Manual, shall be applied to all disturbed areas within fourteen (14) days after final grade is reached. Soil stabilization also shall be applied to all disturbed areas not at final grade which have been inactive for fourteen (14) days.
(4) Control waste. Construction site operators shall control waste such as discarded building materials, concrete truck washout, chemicals, litter, and sanitary waste at the construction site that may cause adverse impacts to water quality.
(b) Structural best management practices for soil stabilization. The following best management practices shall be used to achieve soil stabilization.
(1) Slope stabilization. To minimize the adverse effects of steep embankment slopes, constructed fill slopes and cut slopes shall not be steeper than three (3) feet horizontal to one (1) foot vertical. For slopes of four (4) feet horizontal to one (1) foot vertical or steeper, with slope lengths of greater than one hundred (100) feet, temporary diversion ditches shall be constructed at the top of the slope and every one hundred (100) feet horizontally down the slope.
(2) Mulch. Mulch shall be used as soil stabilization for any disturbed area inactive for fourteen (14) days or longer. Areas requiring stabilization during December through February shall receive only mulch held in place with bituminous material. Mulch shall be used whenever permanent or temporary seeding is used.
(3) Temporary seeding. Temporary seeding shall be used for soil stabilization when grades are not ready for permanent seeding, except during December through February. Only rye grain or annual rye grass seed shall be used for temporary seeding.
(4) Permanent seeding. Permanent seeding shall be applied within fourteen (14) days after final grade has been reached, except during December through February. Permanent seeding shall be applied on any areas that will not be disturbed again for a year, even if final grades have not been reached.
(5) Sod. Sod shall be used for disturbed areas that require immediate vegetative cover as specified in the Stormwater Manual. Sod may be installed throughout the year.
(6) Construction entrance. A stabilized construction entrance, as provided in the Stormwater Manual, shall be constructed wherever vehicles are leaving a construction site to enter a public road, or at any unpaved entrance/exit location. The construction entrance shall be a minimum of fifty (50) feet long, and shall be an on-site measure to be constructed prior to commencing further construction.
(7) Road and parking stabilization. Gravel or paving material, as provided in the Stormwater Manual, shall be used to stabilize permanent roads and parking areas, as well as temporary roads and parking areas used repeatedly by construction traffic. Stabilization shall be accomplished within fourteen (14) days of grading or beginning use for construction traffic.
(8) Dust control. Dust control, as provided in the Stormwater Manual, shall be provided in conjunction with all grading, stripping, excavating, filling or other disturbance of the natural ground cover, and in areas with frequent construction traffic.
(9) Geotextiles. Mulch netting, erosion control matting, or turf reinforcement matting shall be used on sloping areas, and may be used in other areas as specified in the Stormwater Manual.
(10) Gabion mattresses. Gabion mattresses shall be used at the outlets of all culverts and storm drains with an exit velocity greater than five (5) feet per second when flowing full, except where paved ditches are used. Gabion mattresses shall also be used at the outlet of impact stilling basins.
(11) Temporary diversion ditches. Temporary diversion ditches shall be used to collect sediment-laden runoff from disturbed areas, and to direct it to a sediment pond, where applicable. Because temporary diversion ditches are expected to be used for less than one (1) year, no stabilization is required.
(12) Level spreaders. Level spreaders shall be constructed at the outlets of temporary diversion ditches, and at the outlets of permanent constructed waterways where they terminate on undisturbed areas.
(13) Permanent vegetated waterways. Permanent constructed waterways shall be used to divert stormwater runoff from upland undisturbed areas, around or away from areas to be disturbed during construction. Constructed waterways that are expected to be in place for at least one (1) year shall be considered permanent. Permanent waterways shall be lined with sod, nets or mats, or have permanent seeding as provided in the Stormwater Manual.
(14) Pipe slope drains. Whenever it is necessary to convey water down a slope which is not stabilized or which is prone to erosion, pipe slope drains shall be used, unless a paved ditch is used.
(15) Impact still basins. Impact stilling basins shall be used at the outlet of culverts and storm sewers with calculated exit velocities greater an fifteen (15) feet per second when flowing full.
(c) Structural best management practices for sediment control. The following best management practices shall be used to achieve sediment control.
(1) Check dams. Check dams shall be constructed, as provided in the Stormwater Manual, prior to the establishment of vegetation in newly constructed, unpaved, open channels which are used to drain ten (10) acres or less.
(2) Sediment traps. Sediment traps shall be installed, as provided in the Stormwater Manual, below all disturbed areas of less than five (5) acres which do not drain into a sediment pond.
(3) Sediment ponds. Sediment ponds shall be installed, as provided in the Stormwater Manual, below all disturbed areas of five (5) acres or more. The maximum area for a single pond shall be one hundred (100) acres. The pond shall be designed to reduce peak discharges during construction to the pre-development level for the one hundred (100) year, one (1) hour storm.
(4) Silt fences. Silt fences shall be installed, as provided in the Stormwater Manual, down-slope of areas to be disturbed prior to clearing, grading, stripping, excavating, filling or other disturbance of the natural ground cover. The silt fence must be located such that the total area draining to the fence is not greater than one-fourth (1/4) acre per one hundred (100) feet of fence. Silt fences shall be used for storm drain drop-inlet protection and around soil stockpiles.
(5) Storm drain inlet protection. Storm drain inlet protection shall only be used around drop-inlets when the up-slope areas draining to the inlet has no other sediment control.
(6) Filter strips. Filter strips, as provided in the Stormwater Manual, shall be used on each side of streams, wetlands, sinkholes and permanent constructed waterways.
(7) Stream-crossing structures. Stream-crossing structures shall be used at locations where construction traffic, permanent traffic or utilities must cross a stream.
(8) Pump-around flow diversions. Pump-around flow diversions shall be used to divert flow-around construction activities occurring in a stream, when those activities are reasonably expected to cause the erosion or deposit of sediment in a stream.
(Ord. No. 1674, 2-28-05; Ord. No. 1991, § 4, 4-25-22)