The storm water management plan must be designed to meet the Genesee County Storm Water Standards as set out in the companion document to the Low Impact Development Manual for Michigan. The County is authorized to establish minimum design standards for storm water discharge release rates and to require dischargers to implement on-site retention, detention or other methods necessary to control the quality, rate and volume of surface water runoff discharged into the storm water drainage system and surface waters of the State. The County water quality and quantity standards are to be achieved through the techniques and methodologies outlined in the Low Impact Development Manual for Michigan (Chapters 6, 7 and 9). The storm water plan shall identify and contain all of the following:
(a) The location of the development site and water bodies that will receive storm water runoff (National Wetland database). Information to consider and include where appropriate should be the drainage district ID, zoning, aerial imagery, soils and floodplain maps, traffic and utility information.
(b) The existing and proposed natural feature of the development site, including the vegetation, topography, and alignment and boundary of the natural drainage courses, with contours having a maximum interval of two feet (using USGS datum). The information shall be superimposed on the pertinent Genesee County soil map.
(c) The development drainage area to each point of discharge from the development.
(d) Calculations for the existing and final peak discharge rates (based on design criteria).
(e) Calculations for any facility or structure size and configuration.
(f) A drawing showing all proposed storm water runoff facilities with existing and final grades, as well as storm water easements.
(g) The sizes and locations of upstream and downstream culverts serving the major drainage routes flowing into and out of the development site. Any significant off-site and on-site drainage outlet restrictions other than culverts should be noted on the drainage map.
(h) An implementation plan for construction and inspection of all storm water runoff facilities necessary to the overall storm water plan, including a schedule of the estimated dates of completing construction of the storm water runoff facilities shown on the plan and an identification of the proposed inspection procedures to ensure that the storm water runoff facilities are constructed in accordance with the approved storm water plan.
(i) Drawings, profiles, and specifications for the construction of the storm water runoff facilities (BMP) reasonably necessary to ensure that storm water runoff will be drained, stored, or otherwise controlled in accordance with this chapter.
(j) A maintenance agreement, in form and substance acceptable to the Municipality, for ensuring maintenance of any privately-owned storm water runoff facilities. The maintenance agreement shall include the developer’s written commitment to provide routine, emergency, and long-term maintenance of the facilities and, in the event that the facilities are not maintained in accordance with the approved storm water plan, the agreement shall authorize the Municipality to maintain any on-site storm water runoff facility as reasonably necessary, at the developer’s expense (see Sections 1047.100 through 1047.103).
(k) The name of the engineering firm and the registered professional engineer that designed the storm water plan and that will inspect final construction of the storm water runoff facilities.
(l) All design information must be compatible for conversion to standard GIS shape files.
(m) Any other information necessary for the Municipality to verify that the storm water plan complies with the Municipality’s design and performance standards for drains and storm water management systems.
(Ord. 2015-01. Passed 1-26-15.)