A. General Requirement: The excavation, the filling, or any combination thereof, of any lot or parcel within any subdivision shall be in accordance with the approved grading plan submitted as part of engineering plans for said subdivision. No appreciable change to the lot grading shall be allowed without the review and consent of the village engineer.
B. Drainage Overlay: A reproducible mylar drainage overlay drawing with certificate, as required by the Illinois plat act, shall be submitted to the village for approval with the final engineering plans. The drainage overlay drawing shall be at the same scale as the final subdivision plat with designated critical lots noted.
C. Contents Of The Grading Plan: The grading plan shall include the following:
1. Bench mark locations and other control elevations based on USGS datum.
2. Existing and proposed contour lines at a minimum of one foot (1') contour intervals, based upon detailed field verification of ground surface elevations by the design firm of record.
3. Site and any affected adjoining properties' drainage showing existing and proposed channels, swales, lakes, ponds, and structures with control elevations, slopes and cross sections. All existing field tiles shall be located to the property limits, for incorporation into storm sewer plans.
4. Top of foundation elevations and any opening elevations below top of the foundation for any existing or proposed buildings.
5. Finished ground surface elevations at foundation corners, lot corners, top of curbs at property lines extended, drainage inlet structures, and at other ground control points.
6. The parcel drainage shall be designed to flow away from the top of the foundations. Stormwater being directed to the side yard of the parcel shall be directed into a formed drainage swale, having a minimum slope of two percent (2%) in front yard areas, one and one-half percent (11/2%) for all rear yard (and side yard swales to rear) and a maximum slope of six percent (6%). In the event that conditions dictate that some parts of the lot be higher than the structure foundation, the grading plan must show specific drainage configurations for the parcel specifying that all drainage is to be directed to flow away from the foundation in an acceptable manner.
7. Back lot line swales shall be graded to a positive outlet or inlet structure at a minimum flow line slope of one and one-half percent (11/2%) and shall have side slopes of six to one (6:1) or flatter. An inlet shall be provided along a rear yard swale at a maximum two hundred twenty five feet (225') spacing.
8. Construction and work such as walkways, driveways, landscaping or any structure shall be installed so that the construction of same will not interfere with drainage. All sidewalks, driveways, patios and other flat work shall be at an elevation relative to the foundation wall so that water will drain away from the structure on all sides and off the lot in a manner which will provide reasonable freedom from erosion and permanently pocketed surface water.
9. The flow from off site tributary areas that are tributary to an intermittent stream or overflow route that must pass through the parcel must be identified on the grading plan and must be designed in such a way to adequately convey the flow of all surface water for a 100-year storm frequency without damage to adjoining structures.
10. All overflow routes for the 100-year storm and for accumulated stormwater runoff from several lots or from off site catchment areas must be clearly designated on the grading plan with the total width of the flow route contained within an easement for drainage purposes. Engineering grading plans shall call out the 100-year overflow elevation for all overflow tributary areas in excess of five (5) acres. Overflow routes shall be sized for one and one-half cfs/tributary acre, or the calculated peak discharge for the 100-year 24-hour event, whichever is greater. The water surface elevation at overflow shall be one foot (1') below the lowest opening of adjacent structures for tributary areas less than or equal to twenty (20) acres and two feet (2') below the lowest opening for tributary areas greater than twenty (20) acres. All on site overflows shall convey runoff to the proposed detention basin.
11. Critical parcels and lots shall be noted on the grading plan. All revisions noted, dated, and "clouded" to document.
D. Grading Classification Of Lots: In a subdivision or a planned unit development, all rough grading within a given block (or area) must be completed prior to the issuance of any building permits. The developer shall certify in writing that all rough grading is complete within a given block, watershed or other area in strict conformity with the grading plan as approved by the village. The village engineer, or his or her designee, shall verify grading is complete and so notify the village before building can proceed. All proposed drainageways, swales, detention facilities, lot and block grading shall be complete to ensure minimum effect and disturbance upon properties adjoining said development or other portions within the development.
1. Critical Parcels: Those parcels designated as "critical" within said development (as designated and listed on the preliminary engineering plan), shall have a "building spot survey" performed immediately after the foundation has been poured and backfilled to ensure compliance with building setback requirements and to ensure that elevations of any openings in the foundation are in conformance with the approved grading plan requirements of high water restrictions as they relate to the grading plan or stormwater management plan. At the same time, the developer will ensure that the drainage pattern on a particular parcel has not been altered during the course of the foundation construction and backfilling so as to adversely affect the overall drainage plan. Any improper grading deemed by the village engineer to be a potential hazard to any property shall be corrected immediately upon his or her direction or shall be cause for suspension of work on the parcel.
After the structure on a parcel is substantially completed and final grading is completed, the builder shall furnish an occupancy survey signed and sealed by a licensed professional engineer or licensed surveyor to certify that the final ground elevations are in strict compliance with the elevations indicated on the approved grading plan.
The developer shall be responsible for the grading of each lot or parcel through all stages of construction to ensure that drainage from tributary areas is not blocked or hindered and that servient property is protected from damage by providing proper grading to a storm drainage facility in accordance with the approved grading plan.
2. Standard Parcels: Those parcels not designated as "critical" shall be considered as "standard" parcels within said development, and shall have a "building spot survey" performed immediately after the foundation has been poured and backfilled to ensure compliance with building setback requirements and to ensure that rough grading has been substantially completed, so that all drainage flows away from the building to side yards, front yards or rear yards in conformance with the approved grading plan. The village engineer, or his or her designated representative, shall visually inspect all standard parcels at the time rough grading is substantially complete to ensure that yard areas have been rough graded properly before work is allowed to continue beyond the foundation point.
After the structure on a parcel is substantially completed and final grading is complete, the builder shall furnish an occupancy survey signed by a licensed professional engineer to certify that final ground elevations are in strict compliance with the elevations indicated on the approved grading plan. The builder shall pay fee at this time, and survey shall be provided five (5) working days before requested occupancy date.
3. Exceptions: In those cases where conditions, in the opinion of the village engineer, do not permit compliance with the approved grading plan, a revised grading plan must be submitted to the village in the same detail as the original submission requires. In the case of those parcels that need additional detail, the same shall be provided as required by the village engineer.
E. Mass Grading: All site mass grading shall comply with the DuPage soil and water conservation district (KDSWCD) permit requirements. All lots shall be stabilized with seed in accordance with the stormwater ordinance two (2) weeks after the grading is complete.
F. Stockpile: Dirt stockpile(s) shall be located at a site (or sites) on the property which are mutually acceptable pursuant to the approved mass grading plan which must be reduced to writing and approved by the village prior to the actual grading to be conducted in conjunction with each phase of the development. No dirt stockpiles shall be allowed to remain in the development phase after the completion of the last structure in that development phase, and no occupancy permit shall be issued for the last structure in the development phase until all dirt stockpiles are removed from that phase. All dirt stockpiles shall be removed for each phase no later than three (3) years after the first building permit is issued for that phase or prior to the issuance of the last occupancy permit in the phase, whichever is first to occur. Developer shall abide by the village's weed control ordinance in maintaining each dirt stockpile; and any dirt stockpile that remains in the same place longer than two (2) weeks must be seeded or sodded and maintained in that condition for the remainder of the term of that stockpile. No dirt may be stockpiled on a park site. Dirt stockpiles must be maintained in such a way as to minimize the height and to minimize the danger to children, including the removal of all potentially harmful debris. In no event shall a dirt stockpile be left unattended. No dirt stockpile may be located within two hundred feet (200') of the perimeter of the subdivision and no dirt stockpile shall exceed twenty five feet (25') in height, or a gradient ration of two to one (2:1). (Ord. 2015-02-05, 2-5-2015)