POST-CONSTRUCTION STORMWATER MANAGEMENT PROGRAM

The Clean Water Act requires Municipal Separate Storm Sewer Systems (MS4s) to use treatment practices to manage urban stormwater runoff and protect the water quality of the receiving waters. This requirement is addressed in our Post-Construction Stormwater Management Program (PCSMP) where we work toward sustainable watershed management with attention to water quality, water quantity, and flooding issues.

For water quality, the City of Grand Island utilizes a series of vegetated ditches across flat terrain to provide water quality treatment for stormwater runoff within city limits. Our Post-Construction Stormwater BMP Master Plan documents the treatment provided in delineated areas, or sub-basins, of town. Some sub-basins have the capacity to treat more runoff than they receive. These areas with additional capacity allow us to offer treatment credits to projects in areas where space for an ideal stormwater treatment system may not be available. In most instances, water quality requirements have been met by the existing system. For projects to utilize the regional water quality system, approval must be documented in the Subdivision Agreement before development begins. All new stormwater control measures will be required to provide 'as-built' plans. Measures that will be privately owned and maintained will be required to provide documentation of ownership and maintenance responsibilities. Contact the Stormwater Program Manager, (308) 646-6557, or Public Works for water quality credit approval. 

For water quantity, Chapter 33-19.C describes a minimum improvement requirements for storm drainage to detain a 10-year storm at or above pre-construction conditions. All new drainage facilities will be required to provide ‘as-built’ plans. Drainage facilities that will not be publicly owned and maintained will be required to provide documentation of ownership and maintenance responsibilities.

The Post-Construction BMP Master Plan details how the City uses open ditches to treat stormwater runoff within City limits as well as how staff allocates treatment credits for new development projects. Maps of the sub-basins can be found in Appendix A; staff is available to help interpret these maps at (308) 646-6557. Appendix B of the Master Plan has design standards and procedures for projects outside of city limits or projects that are not using our regional water quality treatment system.

Stormwater Treatment Facilities (STFs) that are designed according to the Nebraska Dept of Transportation Drainage Design and Erosion Control Manual are acceptable in our community. Examples of Stormwater Treatment Facilities include:

• Rain Gardens
• Dry Swales & Wet Swales
• Sediment Forebays
• Wet and Dry Retention & Detention Facilities
• Vegetated Ditches & Channels

Post-Construction Stormwater Documents

• Post-Construction Stormwater BMP Master Plan
• Post-Construction Stormwater BMP Master Plan - Appendicies
• Guidance: Designing Stormwater Control Measures

Supplemental Landscaping Documents

• Omaha’s Bioretention Garden Manual for Contractors
• UNL’s Rain Garden Design Guide
• UNL’s Plant Selection for Rain Gardens in Nebraska
• NDOT’s Roadside Vegetation Establishment and Management Manual
• NDOT’s Roadside Flowers and Grasses Pamphlet
• NDOT’s Plan for Roadside Environment Manual

Questions or comments are always welcome and can be directed to the Stormwater Program Manager at (308) 646-6557, the Public Works Department at (308) 385-5455 or digitally via email, Facebook, or Twitter.