AMENDED ORDINANCE O-18-015
(2)
(3)
runoff from a drainage area from a two-year, twenty-four hour
storm, or equivalent control measures, must be provided, where
attainable, until final stabilization of the site. Where no such
calculation has been performed, a temporary (or permanent)
sediment basin providing 3,600 cubic feet of storage per acre
drained, or equivalent control measures, must be provided where
attainable until final stabilization of the site. When computing the
number of acres draining to a common location, it is not necessary
to include flows from off-site areas and flows from on-site areas
that are either undisturbed or have undergone final stabilization
where such flows are diverted around both the disturbed areas and
the sediment basin. In determining whether a sediment basin is
attainable, the operators may consider such factors as site soils,
slope, available area on-site, etc. In any event, the operator must
consider public safety, especially as it relates to children, as a
design factor for the sediment basin and alternative sediment
controls must be used where site limitations would preclude a safe
design.
il, Drainage locations which serve 10 or more disturbed acres at one
time and where temporary sediment basins or equivalent controls
are not attainable, smaller sediment basins and/or sediment traps
should be used. At a minimum, silt fence, vegetative buffer strips,
or equivalent sediment controls are required for all downslope
boundaries (and for those side slope boundaries deemed
appropriate as dictated by individual site conditions).
iil. Drainage locations serving less than 10 acres may utilize smaller
sediment basins and/or sediment traps. At a minimum, silt fence,
vegetative buffer strips, or equivalent sediment controls are
required for all downslope boundaries (and for those side slope
boundaries deemed appropriate as dictated by individual site
conditions) of the construction area unless a sediment basin
providing storage for a calculate volume of runoff from a 2-vear,
24-hour storm or 3,600 cubic feet of storage per acre drained is
provided.
Whenever practical, natural vegetation shall be retained, protected or
supplemented. Priority shall be given to preserving natural drainage systems
including perennial and intermittent streams, wetlands, swales, and drainage
ditches for conveyance of runoff leaving the project area.
Examples of BMPs for erosion and sedimentation control are staked hay straw
bales, filter fences, hydroseeding, and phased development. Many stormwater
BMP technologies (e.g., infiltration technologies) are not designed to handle high
concentrations of sediments typically found in construction runoff and must be
