Lee County Planning Commission recommends change to stormwater rules; vote 3-0

The Lee County Planning Commission voted 3-0 to recommend approval of a proposed text amendment to Title 11, Chapter 4 (Stormwater Management) that would change how the county calculates stormwater detention volumes, Lee County Engineer David Anderson told the commission.

The amendment would alter the design storms used to set release rates and storage volumes. "What we're proposing is that we change that, and we take a 2 year storm on an undeveloped site, and that will be the determined release rate," David Anderson said during the public hearing, adding that the 100-year event would be applied to the undeveloped condition in the revised method.

The proposal is intended both to tidy ambiguous or outdated ordinance language and to reduce detention requirements in many cases, Anderson said. He gave an example range rather than a precise figure: some sites could see reductions in required detention storage on the order of roughly 20% to 60%, with an upper-end example around 50%–60%, while other sites would show smaller changes. "There's actually infinite amount of answers to that question because every site has to be taken on its own merit," Anderson said.

The amendment would also clarify exemptions and use of existing topography. Anderson said the draft would exempt developments on parcels of 11,000 square feet or less; exempt single-family homes; and allow evaluation of large solar projects for exemption when the post-development runoff is demonstrably lower than pre-development runoff. He also told commissioners that where a municipality's stormwater ordinance is more restrictive and applies within roughly 1.5 miles of its boundaries, the municipal requirement would control.

During public comment, a resident who identified herself as Amy asked whether the change was intended to benefit developers and whether the advantage would be financial. Anderson confirmed the change would generally advantage developers but said there was no way to give a single dollar estimate because impacts vary by site.

Commissioners had no additional questions after the public comment period. The commission then moved, seconded and voted to recommend approval of the text amendment by a 3-0 vote. There were no further items on the agenda and the commission adjourned.

The record submitted with the petition includes the amended petition text and a certificate of publication from the Dixon Telegraph, and Anderson testified as representative of the Lee County Engineer's office during the hearing.