The Village of Sugar Grove has adopted the Kane County stormwater ordinance (hereto referred as "stormwater ordinance"), by reference, as its stormwater ordinance. All submittals and designs shall be in accordance therewith. The Village Engineer is the Administrator of the stormwater ordinance.
A. Positive Drainage: Overland flood route shall be labeled on the plans and calculated to convey all the stormwater runoff for the 100-year runoff event to the proposed detention basin assuming the storm sewer system is fully functional and operating under the full head conditions of the 100-year conveyance. Roadways may be used to convey the overland flow route, but shall have a maximum flow depth at the crown of six inches (6") and in no case shall the depth of flow be greater than twelve inches (12"). Reverse parkway slopes and depressed sidewalks shall be used along overflow routes to minimize the depth of water in roadways and the overland flow routes shall be graded such that runoff shall be directed away from homes and structures.
All areas of the property must provide an overland flow path that will pass the 100-year flow. If the tributary area is less than twenty (20) acres, the vertical distance between the 100-year high water level within the overland flow path and the lowest building opening shall be a minimum of one foot (1'). If the tributary area is greater than twenty (20) acres, the 100-year high water level shall be at a stage at least two feet (2') below the lowest opening of any building in the vicinity of the flow path in accordance with the Kane County Stormwater Technical Guidance Manual section T201 (d).
B. Underground Detention: Underground detention will be considered in commercial and industrial applications but shall utilize full stormwater quality improvement methods.
C. Basement Floors: Basement floor elevations in relation to nearby stormwater management facilities normal and high water levels shall be determined by the Village Engineer based on evaluation of the soil strata in the vicinity. At a minimum the basement floors shall be set two feet (2') above the normal water level.
D. Minimum Detention Outlet Size: The minimum size for a single outlet storm detention release pipe shall be twelve inches (12") RCP with a minimum restrictor size of four inches (4") (PVC, SDR-26). If this minimum diameter permits release rates greater than that required, alternate outlet designs shall be utilized which incorporate self-cleaning flow restrictors. If restrictor size is greater than twelve inches (12") then the outlet pipe shall be at least one size larger than the restrictor.
E. Restrictor Type: All innovative restrictor designs that incorporate low maintenance and anti-clogging designs are encouraged and will be considered.
F. Parking Lots: The maximum stormwater ponding depth in any parking area shall not exceed one foot (1') for more than four (4) hours.
G. Overflow Structures: All stormwater detention basins shall be provided with an overflow structure capable of safely passing excess flows at a stage at least one foot (1') below the lowest foundation grade in the vicinity of the basin. The overflow weir shall be designed to convey the proposed critical duration 100-year peak flow entering the basin, shall not exceed one foot (1') of depth and shall have positive downstream conveyance. Once the width and elevation of the weir are established, the basin shall have a minimum of one foot (1') of freeboard above the weir elevation. The overflow weir shall have minimum width of five feet (5') and shall incorporate a concrete curtain wall, four feet (4') longer than the width of the weir on each end, cast in place in a trench cut into the berm, a minimum of forty two inches (42") deep, eight inches (8") wide. Backslope and downstream erosion control measures may be required depending on earth slopes.
H. Setback Requirements:
1. Setback between the high water level of the retention/detention basin and the building/lot: All residential development shall comply with the more restrictive of the following requirements:
a. The high water level plus one foot (1') of freeboard shall not encroach onto a residential lot, or
b. The minimum distance between the residential building envelope and the high water level shall be fifteen feet (15').
I. Early Completion Of Detention Facilities: Where detention, retention, or depressional storage areas are to be used as part of the drainage system for a property, they shall be completed as the first element of the initial earthwork program. This is to ensure that if soil erosion and sediment control practices are not adequately implemented, any eroded sediment will be captured in these areas and will have to be removed by the developer before project completion. Note: Following construction and stabilization of stormwater management facilities, silt fencing shall be installed between the facility and all areas of the subdivision that will have future construction activities. This silt fence shall be maintained until construction activities on all upstream tributary areas have been completed and all such areas have been re-vegetated. All storm sewer inlets to a stormwater management facility shall be installed to the extent that the stabilized basin and post-construction silt fence will not be disturbed by future storm sewer installation.
J. Location Of Basins: Compliance shall be made with 605 Illinois Compiled Statutes 5/9-115.1 regarding the location of basins in relation to the right-of-way. No part of the basin shall be located within a distance of ten feet (10') plus one and one-half (11/2) times the depth of the pond from the right-of-way line.
K. Design Computations: A copy of the design computations, showing contributing areas and other necessary information shall be submitted for approval to the Village Engineer, and shall be submitted by a registered professional engineer and sealed accordingly. All computer generated data shall also be submitted electronically. (Ord. 2018-02-20, 2-20-2018)