Wyoming Administrative Code › Agency 020 - Environmental Quality, Dept. of › Sub-Agency 0011 - Water Quality › Chapter 11 - DESIGN AND CONSTRUCTION STANDARDS FOR SEWERAGE SYSTEMS, TREATMENT WORKS, DISPOSAL SYSTEMS OR OTHER FACILITIES CAPABLE OF CAUSING OR CONTRIBUTING TO POLLUTION AND MOBILE HOME PARK AND CAMPGROUND SEWERAGE AND PUBLIC WATER SUPPLY DISTRIBUTION SYSTEMS › Part C - COMMERCIAL/INDUSTRIAL WASTE AND WASTEWATER FACILITIES › Section 11-31 - Sedimentation Control Facilities

Current through July 13, 2024
This section includes the standards for sedimentation
					 control facilities. Those sedimentation control facilities that are regulated
					 under Water Quality Rules and Regulations, Chapter 2, Appendix J, "Additional
					 Requirements Applicable to Coal Mining Operations" are exempted from this
					 section.
(a) Location. The
				  sedimentation control facilities shall be as near to the affected lands as
				  possible to keep construction and containment volumes to a minimum.
				  Sedimentation control facilities shall be located off-channel when possible.
				  Runoff from unaffected lands should be bypassed around the containment area.
				  All affected lands must drain to a sedimentation control facility.
(b) Basis of design. Sedimentation control
				  facilities shall control all runoff from areas that drain into the facility
				  from a 10-year 24-hour precipitation event in addition to the estimated
				  sediment storage volume for one (1) year be always available. The pond shall be
				  drained down to the permanent pool level as soon as the effluent meets the
				  discharge parameters. The applicant shall demonstrate that equipment or outlet
				  structures are available for draining the pond.
(c) Layout.
(i) Inlet ditches or structures shall not
				  erode or disturb the pond bottom.
(ii) Outlet structures, if used, shall have
				  an overflow device, prevent short-circuiting, prevent floating debris from
				  discharging and shall not erode or disturb the dike. All pipe protruding
				  through a dike shall have adequate seepage control. The point of discharge into
				  a channel shall be protected against erosion and erosion control devices shall
				  be designed based on flow velocities.
(iii) Spillways. Sedimentation control
				  facilities that individually contain more than 2.0 acre-feet of runoff or that
				  individually have more than 2.0 acres of surface area or that are located
				  on-channel shall have a spillway to by-pass precipitation events in excess of
				  the design event. Spillways shall safely pass the 25-year flood event except
				  when the impoundment height is greater than twenty feet or capacity exceeds
				  twenty acre-feet; in which case the spillway shall safely pass the 100-year
				  flood event.
(iv) By-pass ditches.
				  If by-pass ditches are provided to transport runoff from unaffected lands, they
				  shall be designed to pass the runoff from a 25-year precipitation
				  event.
(v) Freeboard. Freeboard
				  shall be provided to protect embankments and dikes from overtopping from wave
				  action and shall be a minimum of one (1) foot above the high water level. For
				  ponds less than two (2) acres, one-half (1/2) foot of freeboard may be
				  acceptable.