TRANSMITTAL LETTER FOR BOARD MEETING OF FEBRUARY 18, 2010
COMMITTEE ON ENGINEERING
Mr. Richard Lanyon, Executive Director
Title
Recommendation to grant a variance with respect to Stormwater Detention Requirements for Des Plaines River Trail Improvements Project
Body
Dear Sir:
The Engineering Department received a letter from the City of Des Plaines (City) dated September 24, 2009 which described a proposed project involving improvements to sections of an existing trail system along the Des Plaines River, and requested clarification as to whether a formal review of the project by the District is required. In its written response dated December 17, 2009, the Engineering Department stated that under the current Sewer Permit Ordinance (Ordinance), a permit is required for the project and that stormwater detention would need to be provided for the new area being disturbed under the development. In a letter to the District dated February 5, 2010, the City contended that a permit should not be required and requested a variance from the District’s standard requirements.
To prevent or mitigate the adverse impacts of new development on flooding, effective January 1, 1972, the Manual of Procedures for the Administration of the Sewer Permit Ordinance (Manual) was amended to add Article 6-4 which requires that in separate sewer areas, stormwater detention be provided for all sewer permit projects exceeding certain acreage limits. The intent of the detention requirements is that the rate of stormwater runoff from a site after its development not exceed the rate of runoff from the area in its undeveloped, natural state.
Article 6-4 of the Manual was further amended in 1998 by revising Section c(1), which now sets forth detention requirements specifically for redevelopments (i.e. totally or partially previously developed areas undergoing development or redevelopment). In administering Article 6-4c(1), if a site undergoing redevelopment is already served by a sanitary sewer, and the site is part or all of a contiguous ownership totaling five acres or more, then stormwater detention is required for the specific area being disturbed or redeveloped (e.g. a new or expanded building within the developed site), regardless of the nature of the development.
In the case of the Des Plaines River Trail Improvement Project, the City plans to stabilize 3.1 miles of an existing dirt trail with a gravel surface. The sections of the trail where improvements will be made are located on Forest Preserve District of Cook County property. At the request of the City, the Engineering Department has revisited this issue and has reviewed the project for its potential adverse impacts on flooding. Considering the fact that the project is linear in nature, that stormwater flows from the project will not affect private property or public rights of way, and will not enter public storm sewers, that the project will not decrease open space and that the trail will be used for recreational purposes, the Engineering Department does not believe this project will increase flooding. While under a purely technical interpretation of the Ordinance and Manual, the disturbance requires detention, in this case, detention facilities would not provide any benefit.
In light of the Engineering Department’s review of this matter, we respectfully recommend that the Board of Commissioners grant the variance requested in this case. It is the Engineering Department’s opinion that the requested variance will cause no harm and will not violate the spirit and intent of the District’s Sewer Permit Ordinance.
If further clarification is required, please advise the undersigned.
Requested, Joseph P. Sobanski, Director of Engineering, WSS:MD
Recommended, Richard Lanyon, Executive Director
Respectfully Submitted, Frank Avila, Chairman Committee on Engineering
Disposition of this agenda item will be documented in the official Regular Board meeting Minutes of the Board of Commissioners for February 18, 2010