For purposes of this chapter, the following definitions shall apply unless the context clearly indicates or requires a different meaning.
AUTHORITY HAVING JURISDICTION (“AHJ”). An AHJ is a political subdivision or other entity (i.e., a city, township, or the Isabella County Drain Commissioner) authorized to issue a storm water permit for a given project. Any political subdivision or entity with infrastructure that is potentially affected by water runoff from the subject site shall be an AHJ with respect to the project, and a separate storm water permit shall be required from each. A property owner in the city wishing to conduct activities subject to the requirements in this chapter shall first contact the City of Mt. Pleasant’s Department of Public Works, which shall administer the permitting requirements of this chapter on behalf of the city and refer the applicant to all other appropriate AHJs. When an AHJ other than the city is exercising jurisdiction over a project located in the city, the terms of this chapter adopted by that particular AHJ shall apply.
ALLOWABLE DISCHARGE. The restricted discharge from a site after development or redevelopment as calculated in accordance with this chapter.
BASE FLOOD. The flood having a 1% chance of being equaled or exceeded in any given year.
BASE FLOOD ELEVATION. The elevation of surface water from a flood that has a 1% chance of equaling or exceeding that level in any given year. The base flood elevation is shown on Flood Insurance Rate Maps (FIRMs).
BASE FLOODPLAIN. The area inundated by the base flood.
BEST MANAGEMENT PRACTICES (BMPs). A practice, or combination of practices and design criteria that comply with the Michigan Department of Environmental Quality’s Guidebook of BMPs for Michigan Watersheds, (including, but not limited to minimizing storm water runoff and preventing the discharge of pollutants into storm water) as determined by the AHJ and/or designer.
BIO-RETENTION AREAS. Areas designed to use soil and plant material to mimic natural processes and store, filter and infiltrate storm water into the ground. These areas may be used anywhere to achieve a degree of storm water treatment.
CLEAN WATER ACT. The Federal Water Pollution Control Act, 33 USC §§ 1251 et seq., as amended, and the applicable regulations promulgated thereunder.
CONDUIT. Any channel, pipe, sewer or culvert used for the conveyance or movement of water whether open or closed.
CONSTRUCTION SITE STORM WATER RUNOFF. Storm water runoff from a development site following an earth change.
CONTROL ELEVATION. Contour lines and points of predetermined elevation used to denote a detention storm area on a plat or site drawing.
DESIGNEE. The engineer formally designated by the AHJ or its appointee to act as its engineer.
DESIGN PROFESSIONAL. Design professional responsible for the design of a drainage plan, who must have appropriate qualifications and licenses to produce types of plans and perform the types of calculations required under this chapter.
DETENTION. The capture of storm water and release over a given period of time through an outlet structure at a controlled rate.
DETENTION FACILITY. A facility constructed or modified to restrict the flow of storm water to a prescribed maximum rate and to concurrently detain the excess waters that accumulate behind the outlet.
DETENTION STORAGE. The temporary detaining or storage of storm water in storage basin, on rooftops, in streets, parking lots, school yards, parks, open space, or other areas under predetermined and controlled conditions, with the rate of drainage regulated by appropriately installed devices.
DEVELOPED or DEVELOPMENT. The installation or construction of impervious surfaces on a development site that requires, pursuant to state law or local ordinance, the AHJ’s approval of a site plan, plat, site condominium, special land use, planned unit development, or the erection of buildings or structures; provided, however, the terms DEVELOPED or DEVELOPMENT do not refer to individual one-family or two-family dwellings or projects involving the construction of such a dwelling, or to projects involving an addition, extension or modification to such dwelling or the parcel on which it is located (since projects requiring a building permit on the site of a one-family or two-family dwelling are subject to the requirements in § 54.03 of this chapter).
DEVELOPER. Any person proposing or implementing the development of land.
DEVELOPMENT SITE. Any land that is being or has been developed, or that a developer proposes for development.
DISCHARGE. The release or outflow of water from any source.
DISCHARGER. Any person or entity that directly or indirectly discharges storm water from any property. DISCHARGER also means any employee, officer, director, partner, contractor, or other person who participates in, or is legally or factually responsible for, any act or omission that is or results in a violation of this chapter.
DRAIN. Any drain as defined in the Drain Code of 1956, as amended, being M.C.L.A. §§ 280.1 et seq., other than an established county or intercounty drain.
DRAINAGE. The collection, conveyance, or discharge or groundwater and/or surface water.
DRAINAGE AREA. The area from which storm water runoff is conveyed to a single outlet (i.e., a watershed or catchment area).
DRAINAGE WAY. The area within which surface water or groundwater is carried from one part of the lot or parcel to another part of the lot or parcel or to adjacent land.
DRAIN COMMISSIONER. The Isabella County Drain Commissioner or his or her designee.
DRAINAGE DISTRICT/WATERSHED. All drainage areas contributing surface water runoff upstream of a discharge location of the proposed development.
DRAINS (PRIVATELY-OWNED). Those drains under private ownership and not under the control of the Drain Commissioner’s office or any other public entity.
EARTH CHANGE. Any human activity, which removes groundcover, changes the slope or contours of the land, or exposes the soil surface to the actions of wind and rain. EARTH CHANGE includes, but is not limited to, any excavating, surface grading, filling, landscaping, or removal of vegetative roots.
EPA. The United States Environmental Protection Agency.
EROSION. The process by which the ground surface is worn away by action of wind, water, gravity or a combination thereof.
EXCESS STORM WATER RUNOFF. The volume and rate of flow of storm water discharged from a drainage area, which is in excess of the allowable drainage.
EXEMPTED DISCHARGES. Discharges other than storm water.
FEDERAL EMERGENCY MANAGEMENT AGENCY (FEMA). The agency of the federal government charged with emergency management.
FLOOD or FLOODING. A general and temporary condition of partial or complete inundation of normally dry land areas resulting from the overflow of water bodies or the unusual and rapid accumulation of surface water runoff from any source.
FLOODPLAIN. Any land area susceptible to being inundated by flood waters from any source.
FLOOD PROOFING. Any combination of structural and nonstructural additions, changes, or adjustments to structures, which reduce or eliminate the risk of flood damage to real estate or improved real property, water and sanitary facilities, or structures with their contents.
FLOODWAY. The channel of any watercourse and the adjacent land areas that must be reserved to carry and discharge a base flood without cumulatively increasing the water service elevation more than one-tenth of a foot due to the loss of flood conveyance or storage.
FLOODWAY OPENING. Any opening of a solid wall such as a window or door, through which floodwaters could penetrate within the floodway.
FOREBAY. These are manmade surface waters used as pretreatment systems. They are designed to temporarily store the first flush of runoff from a storm event and provide for pollutant removal through settling. A FOREBAY or other pretreatment system is recommended at each inlet to a detention system or retention basin.
FOREBAY OUTLETS. Outlets that convey flow from a forebay into detention systems and retention basins. They must include a flow restrictor for restricted flow and a weir for unrestricted flow.
FREEBOARD. A volume of additional storage designed with a detention basin. A safety factor within a storm water detention system that is based on a minimum of one foot detention volume above the proposed high water elevation of a detention pond. This volume provides additional storm water detention in the event that a storm exceeds the design capacity.
GRADING. Any stripping, excavating, filling, and stockpiling of soil or any combination thereof and the land in its excavated or filled condition.
GREEN ROOFS. The roofs are constructed of a lightweight soil medium, layered over a waterproofing membrane. The soil is planted with a specialized mix of plants that can thrive in a roof environment. These types of roofs are also known as VEGETATED ROOF COVERS, ECO-ROOFS, or NATURE ROOFS.
ICDC. The Isabella County Drain Commissioner.
ILLICIT CONNECTION. Any method or means for conveying an illicit discharge into water bodies or the county’s storm water system.
ILLICIT DISCHARGE. Any discharge to water bodies that does not consist entirely of storm water, discharges pursuant to the terms of an NPDES permit, or exempted discharges as defined in this chapter.
IMPERVIOUS SURFACE. Surface that does not allow storm water runoff to percolate into the ground.
INFILTRATION. A process whereby precipitation or groundwater seeps into the ground.
INFILTRATION TRENCH. Also known as a PERCOLATION TRENCH, is a shallow excavated trench, filled with gravel or crushed stone, designed to infiltrate storm water through permeable soils into the ground water aquifer. This type of trench is not considered a preferred means of discharging storm water.
LEACHING BASIN. A catch basin that is fabricated of barrel and riser sections that permit runoff into the ground. This type of basin is not considered an effective means of controlling and treating storm water runoff.
LOCAL BOARD OF APPEALS. The appeals board, if any, designated by the AHJ to review appeals under this chapter. When the city acts as AHJ, the local board of appeals shall be the city’s Building Board of Appeals.
LOW-IMPACT DESIGN (LID). A storm water management strategy that aims to control water, both rainfall and storm water runoff, at the source.
LOWEST FLOOR. The LOWEST FLOOR of the lowest enclosed area (including a basement). An unfinished or flood-resistant enclosure, usable solely for parking vehicles, building access, or storage in an area other than a basement area, is not considered a building’s LOWEST FLOOR, provided that such enclosure is
not built so as to render the structure in violation of requirements.
MDEQ. The Michigan Department of Environmental Quality.
MINIMAL FLOOD PROTECTION ELEVATION (FPE). The base flood elevation plus one foot at any given location. That elevation which provides reliable flood protection above the base flood protection, no less than one foot.
NPDES. The National Pollution Discharge Elimination System.
NREPA. The Natural Resources and Environmental Protection Act, Act 451, of 1994, as amended.
O & M PLAN. An operations and maintenance plan, which describes resource organization, responsibilities, policies, and general procedures.
ONE-FAMILY DWELLING. A building used exclusively for one-family occupancy.
OVERLAND FLOW-WAY. Surface area that conveys a concentrated flow of storm water runoff.
OWNER. Any person or entity having legal or equitable title to property, or any person or entity having or exercising care, custody, or control over any property.
PEAK DISCHARGE. The maximum volume of discharge of storm water runoff at a given location.
PEAK FLOW. The maximum rate of flow of storm water runoff at a given location.
PERSON. An individual, firm, partnership, association, public or private corporation, public agency, instrumentality, or any other legal entity.
PERVIOUS PAVEMENT. A porous surface that allows rainwater to pass directly through into the soil naturally.
POLLUTANT. A substance discharged, which includes, but is not limited to, the following. Any dredged spoil, solid waste, vehicle fluids, yard wastes, animal wastes, agricultural waste products, sediment, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical wastes, biological wastes, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt, and industrial, municipal, commercial and agricultural waste, or any other contaminant or other substance defined as a pollutant under the Clean Water Act.
PROPERTY OWNER. Any person having legal or equitable title to property, or any person having or exercising care, custody, or control over any property.
RAIN GARDEN. A landscaping feature planted with perennial native plants. It is a bowl-shaped or saucer-shaped garden designed to absorb storm water runoff from impervious surfaces such as roofs and parking lots.
REDEVELOPMENT. Altering, improving, or otherwise changing the use of an existing developed property, including, but not limited to, roof, pavement, or any other impervious surface. Ordinary maintenance of impervious surfaces to address the effects of weathering (including, for example, pot hole repair or overlays, crack seal, and seal coating to address pavement defects) does not constitute REDEVELOPMENT. However, crush and shape projects affecting pavement base materials shall constitute REDEVELOPMENT.
RETENTION. The capture and containment of storm water until it infiltrates the soil and/or evaporates.
SOIL EROSION. The stripping of soil and weathered rock from land, creating sediment for transportation by water, wind or ice, and enabling formation of new sedimentary deposits.
STATE OF MICHIGAN WATER QUALITY STANDARDS. All applicable state rules, regulations, and laws pertaining to water quality, including the provisions of Section 3106 of Part 31 of 1994 PA 451, as amended.
STORM DRAIN. A system of open or enclosed conduits and appurtenant structures intended to convey or manage storm water runoff, groundwater and drainage.
STORM WATER PERMIT. A permit issued pursuant to this chapter.
STORM WATER CONTROL PLAN. Written narratives, specifications, drawings, sketches, written standards, operating procedures, or any combination of these.
STORM WATER RUNOFF. The water from a rain storm, snow melt or other natural event or process, which flows over the surface of the ground or is collected in a drainage system.
STORM WATER RUNOFF FACILITY. The method, structure, area, system, or other equipment or measures designed to receive, control, store, or convey storm water.
STREAM. A river, stream or creek, which may or may not be serving as a drain, or any other water body that has definite banks, a bed, and visible evidence of a continued flow or continued occurrence of water.
TAP-IN. Out-letting to an open or closed county drain or municipal storm sewer.
TIME OF CONCENTRATION. The elapsed time for storm water runoff to flow from the most distant point in a drainage area to the outlet or other predetermined point.
TWENTY-FIVE YEAR, 24-FOUR HOUR STORM EVENT. The maximum 24-hour precipitation event with a probable recurrence interval of once in 25 years, as defined by the National Weather Service.
TWO-FAMILY DWELLING. A building used exclusively for the occupancy of two individual families living independently of each other.
UNDERGROUND DETENTION SYSTEMS. An underground system consisting of one or more underground pipes or structures that are designed to provide the required volumes for storage for a development project.
UPLAND AREA. Land located in the upper portion of a watershed whose surface drainage flows toward the area being considered for development.
URBANIZATION. The development, change, or improvement of any parcel of land consisting of one or more lots for residential, commercial, industrial, institutional, recreational, or public utility purposes.
USACE. The United States Army Corps of Engineers, which is responsible for investigating, developing and maintaining the nation’s water and related resources.
VEGETATED SWALES. Channels that are broad, shallow, and lined with vegetation that slow and filter storm water runoff and promote infiltration.
WATER BODY. A river, lake, stream, creek or other watercourse or wetlands.
WATERCOURSE. Any natural or artificial stream, river, creek, channel, ditch, canal, conduit, culvert, drain, waterway, gully, ravine, street, roadway, swale, or wash in which water flows in a definite direction, either continuously or intermittently.
WATERSHED. A region draining into a water body.
WEIR. A low dam built to raise the level of water upstream and regulate its flow. The flow is frequently controlled by a notch through which water flows. WEIR control may be a depression in the side of a tank, reservoir, or channel, or it may be an overflow dam or other similar structure.
WETLANDS. Land characterized by the presence of water at a frequency and duration sufficient to support wetland vegetation or aquatic life as defined by the DEQ.
(Ord. 992, passed 1-12-15; Am. Ord. 1028, passed 10-9-17)