City of Sheridan
Sheridan Stormwater Laws and Regulations
City of Sheridan regulations are compliant with the Wyoming State Stormwater Management Program requirements for the city's small municipal separate storm sewer system (MS4) permit, and with those of Sheridan County.
"The street maintenance division maintains the City of Sheridan’s public roadway network and storm water drainage system. Their work is essential to public safety."
Excerpt- Storm Drainage Design Criteria
Chapter 1 - Purpose
The purpose of this manual is to provide the minimum standards to be used for the analysis and design of storm drainage systems for private development projects and City contracted projects
within the City of Sheridan. These standards apply both to new development as well as improvements within existing developments. Design criteria and methods other than those described in these design standards shall be applied only after requesting and receiving approval from the Public Works Department.
Chapter 2 – Drainage Report Submittal Requirements
A Preliminary Drainage Report shall be prepared by a registered Civil Engineer acting on the Owner’s behalf. All drainage reports must include the design calculations necessary to support
the proposal. Drainage reports shall incorporate the following in approximately this format:
- Provide a brief project summary including the location, description of the existing property
and the proposed development, a discussion of surrounding developments, and the proximity to floodplains.
- Provide a detailed figure for the existing site conditions and a detailed figure for the proposed site conditions that show site boundary, topographic contours, basin/sub-basin area boundaries, drainage structures, wetlands, sensitive area buffers and setbacks, easements, etc. State on each figure the total area and the amount of pervious and impervious area in each
basin/subbasin area. Show flow paths with slope, flow type, surface type, and run length.
- Describe existing conditions including structures, drainage basins, flow paths, pervious/impervious areas, slopes, vegetation/land use, soil type, runoff curve numbers (CN),
time of concentration and other runoff characteristics as well as upstream offsite flow contributions, downstream offsite capacity analysis, and existing drainage problems.
- Describe proposed developed conditions including, drainage basins, flow type and flow paths, pervious/impervious areas, slopes, vegetation/land use, CNs, time of concentration and
other runoff characteristics as well as upstream offsite flow routing, detention or retention storage volume, release rates, overflow route capacity, and proposed storm drainage system.
- Describe applicable State or Federal regulations, design standards, design storm frequencies, as well as hydrologic and hydraulic methods of analysis.
- State runoff control design assumptions and describe method of analysis.
- Appendix: Provide any calculations and figures necessary to support the proposed design, including basin characteristics, time of concentration, weighted Curve Numbers (CN), percent impervious area, runoff hydrograph generation, stage-discharge and stage-storage tables for detention routing, conveyance system capacity calculations, floodplain maps, applicable excerpts from previous reports, correspondence with adjacent property owners, ditch companies, utility companies, or regulatory agencies, or other information necessary to fully document the drainage plan.
Three copies of the Preliminary Drainage Report shall be submitted to the City of Sheridan for
review. The City Public Works Department will return one copy with comments and suggested revisions to the applicant. The applicant shall revise the Preliminary Drainage Report and
submit three copies of the Final Drainage Report along with the Storm Drainage Construction Plans and Details for final review.
Sheridan Storm Drainage Design Criteria (2017)
Sheridan Storm Drainage Criteria (2019)