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The developer shall provide all storm water maintenance agreements necessary to implement the approved drainage plan and to otherwise comply with this chapter in form and substance as required by the City, and shall record such agreements as directed by the City. The maintenance agreements shall, among other matters, assure access for proper inspection and maintenance of storm water runoff facilities and adequate emergency overland flow-ways.
(Ord. 07-2002-10. Passed 7-2-02.)
Prior to final approval, all storm water management facilities for platted subdivisions shall be established as County drains, as authorized in Section 433, Chapter 18 of the Michigan Drain Code (PA 40 of 1956, as amended) for long-term maintenance.
(Ord. 07-2002-10. Passed 7-2-02.)
PERFORMANCE AND DESIGN STANDARDS
In order to achieve the goals and purposes of this chapter, the following three storm water management zones (Zones A, B and C) are hereby established. The Zones are shown on the map attached as Appendix A of original Ordinance 07-2002-10 and incorporated herein by reference.
(a) Zone A. Zone A represents areas which require the most protective storm water management regulations. The goal of this zone is to preserve the natural condition of water bodies included in it, in whole or in part Zone A has, in general, little impervious surface area and few storm water facilities. In this zone, when site conditions permit infiltration of storm water runoff shall be required, rather than the directed flow of storm water runoff into water bodies. This storm water management practice provides greater protection for surface water quality, and also assists in augmenting stream base flow, reduction of flash storm flows and prevention of stream bank erosion. Section 1043.43 of this chapter specifies design criteria for Zone A, in order that the volume and rate of storm water runoff are controlled at predevelopment levels.
(b) Zone B. Zone B represents developed areas that have significant impervious surfaces and storm water runoff facilities in place. The goal of Zone B is the control of storm water runoff in order to prevent further destabilizing of streams and other water bodies. In this zone, the use of detention ponds, the maintenance and enhancement of buffer strips and other measures to reduce directly connected impervious areas are specified in Section 1043.43 of this chapter for the achieving of the storm water management standards applicable to Zone B. The management practices for this zone are intended to maintain existing water quality and to alleviate adverse downstream impact on water bodies.
(c) Zone C. Zone C consists of highly urbanized areas, or areas where there has been significant modification of drainageways. The amount of impervious surface area in Zone C is generally greater than 25 percent. Among the measures required in Zone C, as stated in Section 1043.43 of this chapter, are the use of sediment basins, the maintenance and enhancement of buffer strips along water bodies and the reduction of impervious surface areas that are directly connected to water bodies. An important element of storm water management practice in Zone C is the control and prevention, of sedimentation, in order to reduce pollution of water bodies.
(Ord. 07-2002-10. Passed 7-2-02.)
(d) Storm Water Management Zones.
(1) In any single development site, up to three different detention volumes may be calculated to determine the staged outlet elevations:
A. Water quality control;
B. Bank erosion control; and
C. Flood control.
These volumes are not intended to be additive; the flood control volume shall include the water quality control and bank erosion control volumes.
(2) The default flood control volume shall be based on detaining the 25-year storm frequency so long as the downstream storm water conveyance has adequate capacity and includes an acceptable emergency overland floodway. If the design engineer determines the downstream conveyance system is not adequate or an acceptable emergency overland floodway does not exist, then the flood control volume shall be based on detaining the 100-year storm.
(3) The Planning Commission, as part of its ongoing Master Plan Work, shall designate the Storm Water Management Zones.
(e) Flood Plain Protection.
(1) Natural floodway filling or alteration shall not be allowed without review and approval by the City and compliance with the Floodplain Regulatory Authority found in Part 31, Water Resources Protection, of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended (NREPA) on watercourses with contributing drainage area of two square miles or greater. If a floodway has not been mapped, the applicant's consultant shall provide the floodway delineation to the City for approval.
(2) Natural floodway fringe filling or alteration shall not be allowed without review and approval by the City and compliance with the Floodplain Regulatory Authority found in Part 31, Water Resources Protection, of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended (NREPA) on watercourses with contributing drainage are of two square miles or greater. If a floodplain has not been mapped, the applicant's consultant shall provide the floodplain delineation including the floodway, to the City for approval.
(3) To provide for streambank stability, a buffer zone is to be established and called out on a recorded plat, an approved block grading plan, a site plan, or an improvement plan. This zone shall consist of existing natural tree and vegetation slope protection within a minimum of 25 feet from the ordinary high-water mark. This buffer zone shall be maintained as is, that is, no earth change or disturbance is to take place.
(4) Replacement of lost floodplain shall meet the following criteria:
A. Replacement of the loss of floodplain storage volume at a one to one ratio unless watershed conditions warrant a higher ratio. This applies to floodplain associated with rainfall events up to a 100-year frequency. The grading plan shall provide for an equivalent volume of storage for floodplains associated with more frequent events such as 10 and 25 year frequencies.
B. Storm water detention does not apply toward the replacement volume.
C. Floodplain storage volume shall be computed above the seasonal high ground water level only.
D. The inflow and outflow rates to the area shall be consistent with predevelopment rates.
E. Up to 50 percent of the floodplain mitigation storage volume may be used for snow storage.
F. The proximity of the floodplain mitigation area shall provide for an equivalent hydrologic impact to the receiving stream and adjacent parcels.
(Res. 07-2002-01R. Passed 7-2-02.)
The design standards for storm water runoff facilities for Zones A, B and C, as described in Section 1043.42, are the following:
Zone A | Zone B | Zone C | |
Criteria | High quality waters. Meets water quality standards. Less than 10% imperviousness. | Degraded physical, biological or water quality indicators. 10% to 25% imperviousness. | Heavily degraded physical, biological or water quality indicators. Greater than 25% imperviousness. |
Storm Water Management Standards | Use infiltration basins, infiltration trenches, extended detention basins, and/or constructed wetlands. Maintain and enhance buffer strips. | Use detention ponds, maintain and enhance buffer strips, and reduce directly connected impervious area. | Use sediment basins, maintain and enhance buffer strips and reduce directly connected impervious area. |
Water Quality Control | Detain the first 0.5" of runoff from the contributing watershed, with detention per Zone B and infiltration where conditions permit, or provide equivalent treatment. | Detain the first 0.5" of runoff from the contributing watershed for 24 hours or provide equivalent treatment. | Provide sedimentation control within the drainage system. |
Bank Erosion Control | Rate of release shall be limited to 0.05 cfs/acre for a 2-year storm event. | None | Storm water runoff shall not exceed the capacity of the downstream conveyance system. |
Flood Control | Detention with infiltration when conditions permit. Release rate of 0.13 cfs/acre per KCDC rules. | Release rate of 0.13 cfs/acre per KCDC rules. | Direct conveyance of storm water runoff with the capacity of downstream system. |
(Ord. 07-2002-10. Passed 7-2-02.)
(a) Any drainage situation not involving any public property water is the responsibility of the proper owner.
(b) In plat and site plan review, the City will only review private property drainage for the purpose of assuring that private property can be drained.
(c) Lot grading and private property drainage is a civil matter among the property owners affected.
(d) To aid contractors and builders in grading private property, a lot grading plan will be required on all development and such information shall be disbursed along with the building permit. This lot grading plan must show:
(1) Any established minimum building opening.
(2) Floodway and floodplain elevations.
(3) All storm sewers, the rise, grades, invert elevations and top of casting elevations.
(4) All storm sewer laterals.
(5) All utility and drainage easements and their full description.
(6) Minimum basement elevation for sanitary sewer.
(7) Direction of drainage on each lot.
(8) Elevations of any constructed surface drainage facilities.
(9) Surface grading of the entire parcel.
(e) A minimum rear yard of 25 feet prior to any drainage encumbrance is required. This will allow opportunity for rear yard use for sheds, play equipment, etc., without concern about water damage or inconvenience.
(f) Prior to construction of any structure on a parcel or lot upon which a floodway easement, floodplain and drainageway exists, the permittee must obtain from the City, a copy of the approved plans showing the location and design elevations of that floodway, floodplain and drainageway. Upon completion of the structure and prior to the issuance of an occupancy permit, the permittee must provide a certification from a registered land surveyor that the floodway, floodplain and drainageway grades and dimensions are as designed. If the floodway, floodplain and drainageway does not conform to the approved plans, the floodway, floodplain and drainageway must be reconstructed and certified prior to the issuance of an occupancy permit for that lot or parcel. Concurrent floodway, floodplain and drainageway reconstruction and issuance of an occupancy permit are permitted only if that action does not present a danger to the safety and welfare of any affected property. To permit concurrent action, the permittee shall provide the City with a performance bond, a letter of credit, or a cash deposit to cover the cost of said reconstruction at a dollar amount established by the City.
(Res. 07-2002-01R. Passed 7-2-02.)
The Council of the City may adopt a resolution establishing more detailed design and performance standards for storm water runoff facilities, consistent with the terms of this chapter, and in order to further implement its goals and purposes.
(Ord. 07-2002-10. Passed 7-2-02.)
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