Springfield, IL Environmental Rules: Stormwater Management (2026)

161 requires every subdivision to be developed with adequate surface drainage, using storm sewers, open channels, inlets, catch basins and manholes designed to standards set by the city engineer, and sized to carry not only the site's own runoff but water that naturally drains through the site from other areas. Storm water quality must be considered when the city engineer reviews drainage plans. If development changes surface drainage patterns, the subdivider must make reasonable provision to collect and divert the water into public areas or drains it has rights to use, following accepted engineering practice to avoid damaging neighboring properties.

Where added runoff overloads existing roadside ditches, the developer must improve the ditches and replace culverts to handle the flow. Absent contrary engineering evidence, storm sewers must be designed for a five-year-frequency storm, inlets and catch basins must be spaced so water never flows more than 500 feet overland, and manholes must sit no more than 500 feet apart except where the city engineer approves a greater distance. 5 feet-per-second flow velocity when running full, and manholes must be at least four feet in internal diameter.

Subdividers must also set permanent grade-control monuments along rear-lot drainage swales at intervals of no more than 200 feet, and lot owners are responsible for keeping their drainage courses clear of obstructions. The city engineer can require stormwater detention when necessary, designed per the Illinois Department of Transportation Drainage Manual or an equivalent approved method.