Common Stormwater Utility Fee Definitions

Directly Connected Impervious Area (DCIA) – The portion of IA with a direct hydraulic connection to the permittee’s MS4 or a waterbody via continuous paved surfaces, gutters, drainpipes, or other conventional conveyance and detention structures that do not reduce runoff volume.

Equivalent Hydraulic Area (EHA) – The total runoff area of a parcel that considers both pervious and impervious area.

Equivalent Residential Unit (ERU) – The average IA per residential parcel, equal to the total IA of residential parcels divided by the number of residential parcels. The Village’s ERU is equal to 3,700 square feet.

Impervious Area (IA) – Any surface within a parcel that prevents or significantly impedes the infiltration of stormwater into the soil. Impervious areas include, but are not limited to, buildings, roofed structures, paved areas, walkways, driveways, parking lots, patios, swimming pools, and similar non-porous areas.

Intensity of Development Factor (IDF) – The area within a parcel that is impervious vs. the total area of a parcel, expressed as a percentage. For instance, a 10,000 square foot parcel with 5,000 square feet of impervious area would be assigned an IDF of 50%.

Level of Protection (LOP) – The Level-of-Protection is the frequency with which a storm resulting in structural damage may occur.

National Pollutant Discharge Elimination System (NPDES) Permit – A permit given by Illinois EPA that defines limits on pollutant discharge levels, monitoring and reporting requirements, and other provisions for each permittee.

Non-Residential Parcel – Any parcel that has been developed for use as anything other than Single-Family or Multi-Family

Parcel – An area of land within the corporate limits of the Village that has been established by a plat or other legal means and has been assigned a Property Index Number (PIN).

Pervious Area – A surface that allows the percolation of stormwater into the underlying soil.

Residential Parcel – A parcel which has been identified as being developed as a Single-Family or Multi-Family residence

Stormwater Best Management Practice (BMP) – Structural, vegetative, or managerial practices used to treat, prevent, or reduce water pollution.