The following definitions shall be used with this Ordinance.
accessory building: A non-habitable structure which is on the same parcel of property as the principal structure to be insured and the use of which is incidental to the use of the principal structure.
actual start of construction: Either the first placement of permanent construction of a building on a site, such as the pouring of slab or footings, the installation of piles, the construction of columns, or any work beyond the stage of excavation; or placement of a manufactured home on a foundation.
adequate downstream stormwater capacity: A downstream channel or stormwater management system with the ability to store and convey the anticipated 100-year stormwater runoff without increasing damage to adjoining properties.
Advanced Identification Wetland Study (ADID): A study conducted in McHenry County by the USACE and the USEPA in 1997 to generate wetland maps.
agricultural building: An accessory building that is used solely for agricultural purposes in which the use is exclusively in connection with the production, harvesting, storage, drying, or raising of agricultural commodities, including the raising of livestock.
agricultural land: Land predominantly used for agricultural purposes.
agricultural swale: Grassed waterway or cultivated swale within a farm field under agricultural production which is ephemeral in nature and does not have a defined bed and banks.
applicant: Any person, firm, or governmental agency who owns property or its duly appointed representative and proposes to develop that property and executes the necessary forms to procure a permit to obtain authorization for such regulated development from the Enforcement Officer.
appropriate use: The only regulated development within the designated floodway that is permissible and will be considered for permit issuance. The appropriate uses are determined by IDNR/OWR.
armoring: The placement of materials (concrete, rip-rap, retaining wall, etc.) within a channel or along a shoreline to protect property along streams, lakes or ponds from damage caused by wave action and flowing water.
as-built plans: Record drawings prepared by a licensed land surveyor or licensed professional engineer to confirm that a regulated development was constructed in substantial conformance with the approved plans.
base flood: The flood having a one percent probability of being equaled or exceeded in any given year. The base flood is also known as the 100 year flood event.
base flood elevation (BFE): The water surface elevation that can be expected during the base flood. Determination of the BFE at any location is as described in the Flood Hazard Areas section of this Ordinance.
basement: Any area of a building having its floor below ground level on all sides.
best management practice (BMP): Land planning and engineered practices designed to reduce soil erosion, sediment deposition, and water quality impacts of development.
boardwalk: A walkway constructed of wooden, composite, metallic, or other decking material, primarily serving pedestrian and bicycle traffic.
buffer: An area of predominantly vegetated land located adjacent to WOTUS and IWMC for the purpose of, but not limited to, reducing contaminants in stormwater that flows to such areas.
building: A structure that is principally above ground and is enclosed by two or more rigid walls and a roof. The term includes a gas or liquid storage tank, a manufactured home, mobile home or a prefabricated building. This term also includes recreational vehicles or travel trailers installed on a site for more than 180 consecutive days.
Certified Community: A community which has petitioned the MCSC and has been found by the MCSC to be capable of enforcing an ordinance (or ordinances) which contain rules and regulations which are consistent with or at least as stringent as the regulations of this Ordinance.
Certified Erosion, Sediment and Storm Water Inspector (CESSWI): A certification by EnviroCert International, Inc., which can be earned by demonstrating certain qualifications based on a combination of education and experience, and passing an exam.
Certified Floodplain Manager (CFM): A certification by the Association of State Floodplain Managers, which is designed to establish educational, training and experience criteria related to floodplain management, hazard mitigation, National Flood Insurance Program and to certify that an individual applicant has met these criteria.
Certified Professional in Erosion and Sediment Control (CPESC): A certification by EnviroCert International, Inc., which can be earned by demonstrating certain qualifications based on a combination of education and experience, and passing an exam.
channel: Any river, stream, creek, brook, branch, flow path, slough, ditch, gully, ravine, swale, wash, or drainageway with a discernible bed and banks, in or into which surface or groundwater flows, either perennially or intermittently.
channel modification: Alteration of a channel by changing the physical dimensions or materials of its bed or banks. Channel modification includes damming, rip-rapping or other armoring, widening, deepening, straightening, relocating, lining and significant removal of bottom or woody vegetation of the channel. Channel modification does not include dredging or the clearing of invasive, dead or dying vegetation, debris, or trash from the channel.
Class V injection wells: Any bored, drilled, or driven shaft, or dug hole that is deeper than its widest surface dimension, or an improved sinkhole, or a sub-surface fluid distribution system. This includes most direct infiltration structures such as drywells and column drains. Class V injection wells are regulated by the IEPA and the owner of any proposed injection well is required to submit an inventory information form prior to the infiltration structure becoming operational.
column drain: Any device, including drywells, which facilitates direct infiltration of stormwater runoff below the soil layer (typically greater than five feet).
community: Any municipality (as defined at Ill. Rev. Stat., 1989, Ch. 24, 1-1-2 {1}) or McHenry County when providing services or applying its regulatory authority to the unincorporated portions of the County.
compensatory storage: An excavated volume of storage used to offset the loss of existing flood storage volume when:
A. Fill, materials or structures are placed within a flood hazard area; or
B. A depressional storage area is drained.
Conditional Letter of Map Revision (CLOMR): A letter which indicates that FEMA will revise the BFEs, flood insurance rate zones, flood boundaries or floodway as shown on an effective FIRM, once the as-built plans are submitted and approved.
contiguous property: The lot or parcel of land on which a development is proposed, together with the adjacent lots or parcels of land that were owned in whole, or in part, by the same property owner on the effective date of this Ordinance.
control structure: A structure designed to control the rate of flow that passes through it, based on a specific upstream and downstream water surface elevation.
cosmetic repair: Cleaning, sanitizing, resurfacing (e.g., sanding, repair of joints, re-painting) and similar repairs.
critical duration: The duration of a storm event that results in the greatest peak runoff rate or the greatest peak storage volume required. A critical duration analysis shall compare the peak runoff rates or the peak storage volumes from varying storm durations between the 1 hour and 240 hour events.
dam: All obstructions, wall embankments or barriers, together with their abutments and appurtenant works, if any, constructed for the purpose of storing or diverting water or creating a pool. Underground water storage tanks are not included.
damage: A measurable rise in flood heights on property unless it is contained within the streambanks or a recorded deed or plat restricted area.
deed or plat restriction: Permanent easements, covenants, deed restricted open spaces, outlots, reserved plat areas, and conservation easements dedicated to meet the requirements of this Ordinance, or public road rights-of-way that contain any part of the stormwater management system of a development.
depressional storage area: A non-riverine depression where stormwater collects; only regulated when total storage of an individual depressional storage area exceeds 0.75 acre-feet. Any area within a closed contour and drained by a sewer or culvert with a full-flow capacity greater than 0.10 cubic feet per second per acre (cfs/ac) capacity shall not be considered a depressional storage area.
design storm: A selected storm event, described in terms of the statistical probability of occurring once within a given number of years, for which stormwater or flood control improvements are designed and built.
designated floodway: The channel, including on-stream lakes, and that portion of the floodplain adjacent to a stream or watercourse, as depicted on the FEMA FIRM, which is needed to store and convey the existing 100 year frequency flood discharge with no more than a 0.1 foot increase in stage due to the loss of flood conveyance or storage, and no more than a 10 percent increase in velocities. The need to preserve storage when determining the designated floodway will be waived if all the municipalities and counties along a hydraulically significant portion of the watershed require hydraulically equivalent compensatory storage for all lost floodplain storage volume.
FIGURE 4
Understanding the Floodway
(IDNR Floodplain Management in Illinois Quick Guide, 2001)
detention facility (detention pond/detention basin): A man-made structure for the temporary storage of water with a controlled release rate.
development: Any man-made change to real estate by private property owners or public agencies including, but not limited to:
A. Construction, reconstruction, repair or remodeling, maintenance or placement of a building or any addition to a building, including “ag exempt” buildings;
B. Installing a manufactured home on a site, preparing a site for a manufactured home, or installing a recreational vehicle or travel trailer on a site for more than 180 days (if the recreational vehicle or travel trailer is on the site for less than 180 days, it must be fully licensed and ready for highway use);
C. Drilling, mining, installing utilities, construction of roads, bridges, or similar projects;
D. Demolition of a structure or redevelopment of a site;
E. Construction or erection of levees, walls, fences, dams, or culverts;
F. Channel modification;
G. Filling, dredging, grading, excavating, paving, or other alterations of the ground surface;
H. Storage of materials;
I. Extensive removal of vegetation; or
J. Any other activity of man that changes the height or velocity of flood or surface water.
development site: The portion of contiguous property that is hydrologically disturbed by the development.
drain tile: Sub-surface conduit used for drainage of land, typically for agricultural purposes. Drain tile does not include footing drains.
drain tile survey: An inventory of existing farm and storm drain tiles, typically based upon a field investigation utilizing the slit trench method to locate existing drain tiles.
drainage district: A special district created by petition or referendum and court approval. It has the power to construct and maintain drainage improvements and to pay for the improvements with assessments on the land within the district boundaries. An assessment on the land cannot be greater in value than the benefits of the drainage improvements.
dredging: The maintenance or restoration of a water body by removing accumulated silt, sediment, and other debris from its bed.
dry detention facility: A detention facility designed to drain completely after temporary storage of stormwater. A dry detention facility is normally dry over the majority of its bottom area.
dry floodproofing: Building protection measures designed according to current FEMA guidelines to keep water out of the building. Dry floodproofing measures are among the floodproofing measures described in the following FEMA publications: Engineering Principles and Practices for Retrofitting Flood-Prone Residential Structures (FEMA P-259), Homeowner’s Guide to Retrofitting (FEMA P-312), Selecting Appropriate Mitigation Measures for Floodprone Structures (FEMA 551), Protecting Building Utilities from Flood Damage (FEMA 348), Reducing Damage from Localized Flooding (FEMA 511), Non-Residential Floodproofing – Requirements and Certification (FEMA TB 3), and Floodproofing Non-Residential Structures (FEMA 102).
earth change: Development in which the primary activity is a change in ground elevations affected by the movement of earth materials.
effective date of this Ordinance: January 20, 2004. Subsequent amendments shall be effective upon passage of an amending ordinance.
elevation certificate: A form published by FEMA that is used to certify the lowest floor (including the basement) elevation to which a building has been constructed.
emergency overflow: The structure in a stormwater management facility designed to protect the stormwater management system in the event of a malfunction of the control structure or a storm event greater than the design storm. The emergency overflow capacity initiates at the design high water level of the stormwater management facility.
Enforcement Officer: The MCSC Chief Engineer or the Certified Community’s development regulations officer.
erosion: The process whereby soil is detached by precipitation, flowing water, wind or wave action.
extensive removal of vegetation: Removal of 1 acre or more of vegetation, such as woods or meadow, for non-agricultural purposes and replacement with a surface cover having a higher Runoff Curve Number. The removal of vegetation (in any quantity) consisting primarily of invasive, dead, or dying vegetation shall not be considered extensive removal of vegetation.
farmed wetland: Any wetland that has been identified as a “Farmed Wetland” in accordance with the current “National Food Security Act Manual” (NFSAM) and the current U.S. Army Corps of Engineers – Chicago District methodology.
flood: A general and temporary condition of partial or complete inundation of normally dry land areas from overflow of inland or tidal waves, or the unusual and rapid accumulation of runoff of surface water from any source.
flood damage: A measurable rise in flood heights at a building currently subject to flooding, or flooding of a building not currently subject to flooding.
flood damage-resistant materials: Any building product (material, component or system) capable of withstanding direct contact with floodwaters for at least 72 hours without sustaining damage requiring more than cosmetic repair. FEMA Technical Bulletin 2 provides guidance in the classification of flood damage-resistant materials.
flood frequency: A frequency, normally expressed as a period of years, that a flood of a stated magnitude can be expected to be equaled or exceeded, based upon a statistical analysis of the percent chance of occurrence in any given year.
flood fringe: That portion of the floodplain outside of a designated floodway. No flood fringe exists within a floodplain that has a non-designated floodway.
flood hazard area: The land located in a floodway, floodplain, or flood prone area subject to the base flood.
FIGURE 5
Flood Hazard Areas
Flood Hazard Area Development: Regulated development located partially or completely within a floodway, floodplain, or a flood prone area.
Flood Insurance Rate Map (FIRM): A map prepared by FEMA that depicts the floodplain, designated floodways, and flood insurance risk premium zones within McHenry County. The effective dates of the FIRMs in McHenry County are listed in Appendix 11. The effective FIRMs may be amended or revised by a LOMC.
Flood Insurance Study (FIS): A report published by FEMA for McHenry County in conjunction with the McHenry County’s FIRMs. The effective date of the McHenry County FIS is shown in Appendix 11. The study contains such background data as the base flood discharges and water surface elevations that were used to prepare the FIRMs. The effective FIS may be revised by a LOMC.
flood prone area: Any area inundated by the base flood and located outside the limits of the floodplain that:
A. Has a tributary area greater than 100 acres,
B. Is a depressional storage area, or
C. Is mapped as a Flood of Record area on the USGS-Hydrologic Investigation Atlas Flood of Record Maps.
flood protection elevation (FPE): The BFE plus 2 feet of freeboard, except in the case of attached garages and small accessory buildings, where the FPE is the BFE plus 0.5 foot of freeboard.
floodplain: Those lands within the jurisdiction of McHenry County and its municipalities that are subject to inundation by the base flood. The floodplains of McHenry County are identified on the FIRMs of McHenry County prepared by FEMA. The effective dates of the FIRMs in McHenry County are listed in Appendix 11. The effective FIRMs may be amended or revised by a LOMC. The floodplain includes areas identified on the FIRMs as Zones A, AO, AH, AE, A99, AR, AR/AE, AR/AO, AR/AH, or AR/A.
FIGURE 6
Understanding the Riverine Floodplain
(IDNR Floodplain Management in Illinois Quick Guide, 2001)
floodplain management: An overall program of corrective and preventive measures for avoiding or reducing future flood damage.
floodproofing: Any combination of structural and non-structural measures, changes or adjustments to buildings or property which reduce or eliminate flood damage to real estate or improved real property, water and sanitary facilities, buildings and their contents. (See also dry floodproofing and wet floodproofing.)
floodproofing certificate: A form published by FEMA that is used to certify that a non-residential building has been designed and constructed to be structurally dry floodproofed up to the FPE.
floodway: See designated floodway and non-designated floodway.
freeboard: An increment of height added to the BFE or a design high water elevation to provide a factor of safety for uncertainties in calculations, unknown local conditions, wave actions and unpredictable effects such as those caused by ice or debris jams.
functional assessment: An assessment of a wetland’s flood storage, water quality and other beneficial functions.
General Permit: A stormwater management permit pertaining to a specific type of regulated development, which may be issued by MCSC or a Certified Community in order to streamline the permit process for a routine project. Each General Permit specifies the terms and conditions for a specific type of regulated development to assure compliance with the purpose and intent of this Ordinance. Valid General Permits are listed in Article III of this Ordinance.
green infrastructure: Any stormwater management technique or practice that reduces runoff volume through preserving, restoring, utilizing, or enhancing the processes of infiltration, evapotranspiration, and reuse. Approaches may include, but not be limited to, green roofs, naturalized detention facilities, trees and tree boxes, rain gardens, vegetated swales, wetlands, infiltration planters, porous and permeable pavements, porous piping systems, dry wells, vegetated median strips, reforestation/revegetation, rain barrels and cisterns, and protection and enhancement of riparian buffers and floodplains.
HEC-1: Hydrograph producing hydrologic computer model created by the USACE in the Hydrologic Engineering Center.
HEC-2: Hydraulic step backwater computer model created by the USACE in the Hydrologic Engineering Center.
HEC-RAS: Windows™ based hydraulic step backwater computer model created by the USACE in the Hydrologic Engineering Center.
High Functional Value Wetland (HFVW): Any WOTUS or IWMC identified as such on the ADID Maps or any WOTUS or IWMC that, through a functional assessment, meets the criteria defined in that Study for determining high functional value, related specifically to hydrological and water quality functions.
High Quality Aquatic Resource (HQAR): WOTUS or IWMC that are determined to be critical due to their uniqueness, scarcity, function and/or value. The following types of WOTUS or IWMC are considered HQAR.
A. ADID wetland and aquatic sites.
B. Bog: A low nutrient peat land, usually in a glacial depression, that is acidic in the surface stratum and dominated by the genus Sphagnum.
C. Ephemeral pool: A seasonally inundated depression within forested or open areas, usually located on a moraine, glacial outwash plain, or in an area shallow to bedrock; also known locally as a “vernal pool.” These areas may or may not be permanently vegetated.
D. Fen: An herbaceous or wooded peat land created and maintained by the constant surface water flow of cold mineralized (calcareous) groundwater flow.
E. Forested wetland: A wetland, including wooded seeps, shrub swamps, and floodplain forests, dominated by shrubs or trees growing on soils that are inundated or saturated much of the year, but that do dry out at the surface.
F. Sedge meadow: Saturated, sometimes flooded open wetlands dominated by grasses and sedges, including hummock forming Tussock Sedge (Carex stricta).
G. Seep: A wetland, herbaceous or wooded, with saturated soil or inundation resulting from the diffuse flow of groundwater to the surface stratum.
H. Streams: Perennial and intermittent streams, provided that the stream is not WOTUS and that the IBI is greater than 35, or that the stream is classified as Class A or Class B in the Biological Stream Characterization System of the IEPA.
I. Streamside marsh: A wetland that is within a 100 year riverine floodplain and dominated by herbaceous species.
J. Wet prairie: A wetland dominated by native graminoid species with a diverse indigenous forb component that is seasonally saturated and/or temporarily inundated.
K. Wetlands supporting Federal or Illinois endangered or threatened species.
L. Wetlands with a FQI of 20 or greater or a mean C-value of 3.5 or greater, as determined by the methodology described in Plants of the Chicago Region (Swink, F. and G. Wilhelm, 1994, 4th Edition, Indianapolis: Indiana Academy of Science).
M. Wetlands that are within a designated Illinois Natural Areas Inventory Site or McHenry County Natural Areas Inventory Site.
High Quality Habitat Sites (HQHS): WOTUS or IWMC that are identified as having high quality wildlife habitat, high floristic quality or high quality aquatic habitat based on the ADID Maps; or meets the criteria defined in the ADID Study through a functional assessment.
highest adjacent grade: The highest natural ground elevation in an area of interest, such as next to the proposed walls of a building.
historic structure: A structure that is:
A. Listed individually in the National Register of Historic Places or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register;
B. Certified or preliminarily determined by the Secretary of the Interior as contributing to the historic district or a district preliminarily determined by the Secretary to qualify as a registered historic district;
C. Individually listed on the State inventory of historic places by the Illinois Historic Preservation Agency; or
D. Individually listed on a local inventory of historic places that has been certified by the Illinois Historic Preservation Agency.
HY-8: Culvert hydraulic analysis program created by the Federal Highway Administration.
hydraulically equivalent compensatory storage: Compensatory storage that can be shown by hydrologic and hydraulic calculations to offset the loss of existing flood storage volume. The storage volume displaced below the existing 10 year frequency flood elevation must be replaced below the proposed 10 year frequency flood elevation. The storage volume displaced above the existing 10 year frequency flood elevation must be replaced above the proposed 10 year frequency flood elevation.
hydrologic and hydraulic calculations: An engineering analysis which determines expected flood flows and flood elevations based on land characteristics, sub-surface drainage characteristics, and rainfall events.
hydrologically disturbed: An area where the land surface has been cleared, grubbed, compacted, graded, excavated, filled or otherwise modified in a manner that changes runoff volumes, or rates.
impervious surface, impervious area: Any hard-surfaced, compacted area that does not readily absorb or retain water, including but not limited to building roofs, asphalt and concrete surfaces, and graveled areas.
in-kind replacement: A replacement culvert, storm sewer, or drain tile that has an equivalent cross-sectional area and shape, with the same material or a smoother material. In-kind replacement of a culvert, storm sewer, or drain tile includes minor adjustment of pipe invert elevations to correct an adverse slope.
Index of Biotic Integrity (IBI): Ecologically based water quality score calculated from multiple types of fish data utilized to classify streams. An initial IBI may be obtained from the biannual IEPA Illinois Water Quality Report, but a site specific IBI assessment may override the initial IBI.
individual permit: Any stormwater management permit which does not meet the terms and conditions of a General Permit.
infiltration facility (infiltration pond/infiltration basin): A facility designed to completely retain a specified amount of stormwater runoff without release except by means of infiltration. A rain garden shall not be considered an infiltration facility.
initial construction: The date the first building permit was issued, provided the actual start of construction, repair, reconstruction, rehabilitation, addition placement, or other improvement was within 180 days of the permit date.
inspect: To check or to review a site for compliance with this Ordinance, permitted plans and permit conditions.
Intermediate Development: Regulated development that:
A. Consists of hydrologic disturbance between 20,000 square feet and 1 acre; and
B. Is not a Public Road Development or Mining Development.
intermittent stream: A stream that has flowing water during certain times of the year, when groundwater provides water for stream flow. During dry periods, intermittent streams may not have flowing water. Runoff from rainfall is a supplemental source of water for stream flow. Intermittent streams are depicted on the USGS Quadrangle Maps with a dashed blue line.
Isolated Waters of McHenry County (IWMC): All waters such as rivers, lakes, ponds, streams (including intermittent streams), farmed wetlands, and wetlands that are not under USACE jurisdiction.
A. The limits of the IWMC extend to the ordinary high water mark or the delineated wetland boundary.
B. IWMC exclude excavations created for such purposes as stormwater conveyance, detention/retention areas constructed as part of a stormwater management system, recreation, mining, stock watering, irrigation, settling basins or wastewater treatment systems and roadside ditches, provided that the excavation has been permitted or that no permit was required at the time of the excavation.
C. Mitigation sites where wetlands or waters were created to meet the requirements of this Ordinance or Section 404 of the Clean Water Act are not excluded.
IWMC impact: IWMC that are disturbed or otherwise adversely affected, whether temporarily or permanently, by development. Trenchless installation of utilities beneath IWMC does not constitute an IWMC impact, provided that no soil is disturbed within the limits of the wetland, the installation does not drain the IWMC, and no drilling fluids are discharged into the IMWC.
IWMC mitigation: Compensation for impacts to IWMC through the restoration, creation, enhancement of wetlands or waters.
lake: A body of water encompassing an area of 2 or more acres which retains a normal water level throughout the year.
Letter of Map Amendment (LOMA): An official determination by FEMA that a specific building or parcel of land is above the BFE and was inadvertently included in a floodplain provided that the natural ground elevation has not been altered. A LOMA amends the effective floodplain limits on a FIRM. A LOMA does not modify a floodway limit or the BFE.
Letter of Map Change (LOMC): A LOMA or LOMR.
Letter of Map Revision (LOMR): Letter issued by FEMA or IDNR/OWR that revises BFEs, flood insurance rate zones, flood boundaries or floodways as shown on an effective FIRM.
licensed land surveyor: A surveyor licensed in the State of Illinois, under the Illinois Professional Land Surveyor Act of 1989 225 ILCS 330/1, et seq.(1994 State Bar Edition).
licensed professional engineer: An engineer licensed in the State of Illinois, under the Professional Engineering Practice Act of 1989 225 ILCS 325/1, et seq. (1994 State Bar Edition).
low opening elevation: The elevation at which water could enter a building through any non-watertight opening such as a doorway threshold, a window sill, the top-of-foundation, or a basement window well.
lowest adjacent grade: The lowest finished grade adjacent to a building, not including the bottom of window wells.
lowest floor: The lowest floor of the lowest enclosed area, including a basement. An unfinished or wet floodproofed enclosure, usable solely for parking of 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 building in violation of the applicable non-elevation design requirements of this Ordinance.
maintainable outlet: A new storm sewer or overland flow path that discharges to an existing stormwater management system or channel.
maintenance of existing buildings: Re-roofing, replacement of windows, re-siding, carpeting, painting, installing a new water heater, installing a new electric service, and maintenance tasks that do not require a building permit.
maintenance of existing roads and trails: Rehabilitative maintenance, such as milling and overlaying, that does not increase the impervious area and does not increase the surface elevation. Maintenance of existing roads and trails also includes increasing the surface elevation with the following limitations:
A. Resurfacing outside flood hazard areas;
B. Resurfacing within flood prone areas;
C. Resurfacing within the flood fringe, provided the difference between the elevation of the road surface after resurfacing and the elevation of the road surface on the effective date of this Ordinance is not more than two inches.
maintenance plan: A plan for the perpetual maintenance of the stormwater management system, including wetlands, waters and buffer areas. A maintenance plan shall include the following:
A. Planned maintenance tasks and the frequency of each task such as removal of sediment, debris, mowing and pruning of vegetation, and restoration of eroded areas;
B. Identification of the party responsible for performing each task; and
C. A description of applicable deed or plat restrictions.
Major Development: Regulated development that is not classified as a Minor Development, Intermediate Development, Public Road Development, or Mining Development.
major stormwater system: The portion of a stormwater management system needed to store and convey flows for the base flood event.
manufactured home (or mobile home): A structure, transportable in one or more sections, which is built on a permanent chassis and is designed for use with or without a permanent foundation when connected to the required utilities. The term manufactured homes also includes park trailers, travel trailers and other similar vehicles placed on site for more than 180 consecutive days. The term manufactured home does not include a recreational vehicle or travel trailer.
manufactured home park (mobile home park, trailer park): A parcel (or contiguous parcels) of land on which two or more manufactured homes are harbored, either free of charge, for rent or for sale.
McHenry County Stormwater Management Commission (MCSC): The Commission established and existing under 55 ILCS 5/5-1062 (1994 State Bar Edition) for the purposes of developing, revising and implementing a countywide stormwater management plan and ordinance.
MCSC Chief Engineer: A licensed professional engineer representing the MCSC as the Enforcement Officer of this Ordinance.
Mining Development: Regulated development that:
A. Consists of extracting and/or mining mineral or aggregate resources; and
B. Is conducted upon a recorded parcel of land exceeding 2 acres; and
C. Involves the removal of 10 feet or more of overburden.
Minor Development: Regulated development that:
A. Consists of hydrologic disturbance of less than 20,000 square feet; and
B. Is not a Public Road Development or a Mining Development.
minor stormwater system: All infrastructure including curb, gutter, culverts, roadside ditches and swales, storm sewers, drain tiles, subsurface drainage systems, and other practices intended to convey or capture stormwater runoff from storm events less than the base flood event.
mitigation: Measures taken to offset negative impacts from development activities, such as construction in wetlands, waters and flood hazard areas. Wetland mitigation typically involves wetland restoration or enhancement. Floodplain and flood prone area mitigation typically involves compensatory storage and created conveyance capacity.
mitigation plan: A plan to mitigate IWMC impacts.
multi-county municipalities: A municipality containing corporate area within both McHenry County and an Illinois county located contiguously adjacent to McHenry County.
mobile home: See manufactured home.
National Flood Insurance Program (NFIP): The requirements of the NFIP are codified in Title 44 of the Code of Federal Regulations.
National Geodetic Vertical Datum of 1929 (NGVD29): Reference surface set by the National Geodetic Survey deduced from a Continental adjustment of all existing sea level adjustments in 1929. Mean Sea Level for 1929 (MSL adj. 1929), is an equivalent. Refer to the FIS for conversion between NGVD29 and NAVD88.
native vegetation: Generally, all warm season, deep rooted, grass and forb species believed to have grown naturally in the pre-settlement landscape of northern Illinois and southern Wisconsin.
natural ground elevation: The elevation of the ground on September 30, 1981, which was the effective date of the first FIRM in McHenry County.
natural streams and channels: Streams and channels formed prior to changes made by man. A modified stream or channel which has regained natural characteristics over time as it meanders and re-establishes vegetation may be considered natural.
new construction: Buildings for which the initial construction commenced on or after the effective date of a floodplain management regulation adopted by a community and includes any subsequent improvements to such buildings.
new impervious area: Impervious surface area created after the effective date of this Ordinance.
non-designated floodway: The channel, including on-stream lakes, and that portion of the floodplain adjacent to a stream or watercourse, not specifically identified as a floodway on the FEMA FIRM, but which has a tributary area of 640 acres or more in an urban area or a tributary area of 6,400 acres or more in a rural area. The urban area or rural area designations shall be determined by IDNR/OWR.
non-residential building: A commercial or industrial building. An accessory building is not considered a non-residential building.
non-riverine: Areas not associated with a stream or river, such as isolated depressional storage areas, ponds and lakes.
North American Vertical Datum of 1988 (NAVD88): A datum that supersedes the NGVD29. Refer to the FIS for conversion between NGVD29 and NAVD88.
online detention: Any detention facility that receives runoff from an offsite area or from an onsite area that is not hydrologically disturbed.
open channel: A conveyance system with a definable bed and banks carrying the discharge from field tiles and surface drainage including a ditch, culvert, stream, creek, and river. An open channel does not include grassed swales or cultivated swales within a farm field under agricultural production which are ephemeral in nature.
ordinary high water mark: The point on the bank or shore at which the presence and movement of surface water are continuous so as to leave a distinctive mark, such as by erosion, destruction or prevention of terrestrial vegetation, predominance of aquatic vegetation, or other such recognized characteristics.
other maintenance activity: Rehabilitative maintenance that is not maintenance of existing buildings or maintenance of existing roads and trails, including but not limited to:
A. Repair or replacement of existing driveways or parking lots within the same footprint and outside flood hazard areas;
B. Repair or replacement of existing driveways or parking lots within the same footprint and within flood prone areas;
C. Repair or replacement of existing driveways or parking lots within the same footprint and within the flood fringe, provided the difference between the elevation of the paved surface after repair or replacement and the elevation of the paved surface on the effective date of this Ordinance is not more than two inches;
D. Repair of existing underground and overhead utilities, provided the repair does not result in any IWMC impact;
E. Repair or in-kind replacement of existing culverts, storm sewers, or drain tiles, provided the culverts, storm sewers, or drain tiles are outside the designated floodway and have a cross-sectional area less than 12.6 square feet;
F. Repair, not including in-kind replacement, of an existing bridge outside the designated floodway;
G. Maintenance of drainage ditches (i.e., dredging and the removal of obstructive, invasive, dead, or dying vegetation), outside the designated floodway, provided that spoil materials: are removed from the flood hazard area and are spread thinly and incorporated into existing cultivated areas; or are hauled away from the development site; and provided that appropriate soil erosion and sediment control practices are utilized. Maintenance of drainage ditches does not include ditch straightening, ditch widening, flood hazard area fill, soil stockpiles or the construction of any new channel or water body;
H. Dredging of ponds, outside the designated floodway, provided that spoil materials: are removed from the flood hazard area and are spread thinly and incorporated into existing cultivated areas; or are hauled away from the development site; and provided that appropriate soil erosion and sediment control practices are utilized. Dredging of ponds does not include the construction of any new pond or water body;
I. Removal of any obstruction from a channel, culvert, or storm sewer to restore its original design or permitted condition. Removal of obstruction does not include channel straightening, channel widening, flood hazard area fill, soil stockpiles, or the construction of any new channel or water body; and
J. Maintenance to restore an existing stormwater management facility to its original design or permitted condition (the Enforcement Officer may also allow minor modifications to an existing stormwater management facility to reduce the need for future maintenance).
outfall: Discharge or point of discharge of a culvert or other closed conduit from a development at which stormwater can be released from the development site without causing scour, erosion, flooding, sedimentation or produce any damage in the receiving system.
overland flow path: The route that stormwater will travel based on the topography of the land. Overland flow paths are typically viewed without consideration of infiltration, evaporation or underground drainage structures.
oversight committee: A decision-making authority designated by a Certified Community or McHenry County. For a Certified Community, the oversight committee may be comprised of the corporate authorities or any committee thereof, plan commission, zoning board of appeals, or other existing body, or the corporate authorities may, according to their own rules and procedures, establish a separate oversight committee. The Committee of the McHenry County Board that the Planning and Development Department reports to shall act as the oversight committee for McHenry County.
parcel identification number (PIN): Permanent index number used to identify properties.
perennial stream: A water course which intersects the groundwater table and flows throughout the year, depicted on the USGS Quadrangle Maps with a solid blue line.
performance guarantee: A bond, surety, letter of credit, or other instrument used to ensure regulated development conforms with the requirements of this Ordinance and the terms and conditions of the stormwater management permit.
permanent erosion control: Permanent features of a development site designed to control soil erosion and sedimentation.
permeable pavement: Porous asphalt, pervious concrete, permeable pavers and similar paving materials designed to promote stormwater infiltration. Permeable pavement is not considered an impervious surface, provided that it is constructed over soil which can be shown by development site specific soil data to be sufficiently permeable to allow infiltration without a system of underdrains and provided that the full depth of the pavement cross-section is above the seasonal high groundwater elevation.
pond: A body of water of less than 2 acres which retains a normal water level year round.
precipitation: Any form of water, such as rain, snow, sleet or hail that falls to the earth’s surface.
pre-treatment: BMPs used to remove pollutants from stormwater prior to infiltration.
public bodies of water: All open public rivers, streams, and lakes specifically designated by IDNR/OWR. The IDNR/OWR designated public bodies of water are listed in Appendix 8. Generally, public bodies of water are capable of being navigated by watercraft, in whole or in part, for commercial uses and purposes, or which in their natural condition were capable of being improved and made navigable, or that are connected with or discharge their waters into navigable lakes or rivers within, or upon, the borders of the State of Illinois, together with all bayous, sloughs, backwaters, submerged lands and lakes that are open to the main channel or body of water and directly accessible thereto.
public flood control project: A flood control project which will be operated and maintained by a public agency to reduce flood damages to existing buildings and structures, including hydrologic and hydraulic calculations of the existing and proposed conditions of the watershed. Nothing in this definition shall preclude the design, engineering, construction or financing, in whole or in part, of a flood control project by persons or parties who are not public agencies.
Public Road Development: Regulated development that:
A. Takes place in a public right-of-way or part thereof; and
B. Does not include the construction of a building; and
C. Consists of culverts, bridges, roadways, sidewalks, bike paths and related construction. Public recreational trails and linear railroad developments shall be considered Public Road Development with respect to the requirements of this Ordinance, even if the public recreational trail or linear railroad development is not located within a public right-of-way.
qualified inspector: A person knowledgeable in the principles and practices of erosion and sediment control measures, such as a licensed professional engineer, a Certified Professional in Erosion and Sediment Control (CPESC), a Certified Erosion, Sediment and Storm Water Inspector (CESSWI) or other knowledgeable person who possesses the skills to assess conditions at the development site that could impact stormwater quality and to assess the effectiveness of any sediment and erosion control measures selected to control the quality of stormwater discharges from the construction activities.
rain garden: A small, shallow depression planted with flowers, grasses or other vegetation that is designed to collect stormwater runoff from surrounding areas. Rain gardens are typically less than 300 square feet in size with a depth less than 12 inches.
Rational Method: An empirical formula that relates stormwater runoff to rainfall intensity, surface area and surface characteristics.
recreational vehicle or travel trailer: A vehicle which is built on a single chassis; 400 square feet or less when measured at the largest horizontal projection; designed to be self-propelled or permanently towable by a light duty truck; and designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use.
redevelopment: The process of developing land previously developed.
regulated development: Development that meets any of the criteria listed in Article II, Section B of this Ordinance, unless the development is specifically exempted in Article II, Section C of this Ordinance.
repair or remodeling: Development activities which do not result in any changes in the outside dimensions of a building, any changes to the dimensions of a structure or increase in impervious area.
repetitive loss: Flood-related damages sustained by a building on two separate occasions during a 5 year period for which the cost of repairs at the time of each such flood event, on the average, equals or exceeds 25 percent of the market value of the building before the damaged occurred.
retention facility (retention pond/retention basin): See infiltration facility.
riverine: Relating to, formed by, or resembling a stream (including creeks and rivers).
runoff: See stormwater runoff.
Runoff Curve Number: An empirical parameter developed by the NRCS and used for predicting direct runoff or infiltration from excess rainfall.
rural area: The rural area designation within non-designated floodways shall be determined by IDNR/OWR. In flood prone areas, all residential, commercial or other non-residential land uses that are not defined as or included within an Urban Area, as defined by the U.S. Department of Commerce, Census Bureau (USCB) or as approved by the Enforcement Officer.
sediment basin: A permanent, wet-bottom basin created to detain sediment-laden stormwater runoff long enough for sediment or other water-based debris to settle to the bottom.
sediment trap: A temporary structure formed by construction of an embankment or excavation of a basin in order to detain sediment-laden stormwater runoff from a disturbed area of 5 acres or less long enough for sediment or other water-based debris to settle to the bottom.
sedimentation: The processes that deposit soils, sediment, debris, and other materials.
silt fence: A temporary barrier of entrenched geotextile fabric (filter fabric) stretched across and attached to supporting posts used to intercept sediment laden runoff from small tributary areas of disturbed soil.
small accessory building: An accessory building that:
A. Is less than 600 square feet in size; and
B. Is less than $22,150 in value; and
C. Is only used for the storage of vehicles and/or tools; and
D. Is accessory to a residential building.
soil stockpile: 100 cubic yards or more of soil that remains in place for 7 or more days.
start of construction: The date on which a regulated development commenced.
stormwater management: A set of actions taken to control stormwater runoff with the objectives of providing controlled surface drainage, flood control and pollutant reduction in runoff.
stormwater management facility: A detention facility or infiltration facility.
stormwater management permit: A permit established by this Ordinance which signifies conformance with the provisions of this Ordinance. A stormwater management permit may be issued as a General Permit or as an individual permit.
stormwater management permit application: A form provided my McHenry County or a Certified Community that includes the following information:
A. The name and legal address of the applicant;
B. The PIN or legal description of each parcel comprising proposed development;
C. A written description of the proposed development;
D. The proposed hydrologically disturbed area;
E. The existing and proposed impervious area and the impervious area that existed at the development site prior to the effective date of this Ordinance;
F. Approximate start and end dates of the proposed development; and
G. A statement of intent to comply with the requirements of this Ordinance, signed by the applicant.
stormwater management system: The major and minor stormwater system for a development.
stormwater runoff: Precipitation that flows off of permeable and impermeable surfaces.
stormwater storage: Temporary detention or retention of stormwater with a controlled release rate or with release by means of infiltration.
stream: A course of running water flowing in a channel (includes creeks and rivers).
StreamStats: A web-based Geographic Information System developed by the USGS that delineates the watershed boundary and estimates stream flow statistics for a user selected site.
structural dry floodproofing: Building protection measures designed to make the building and its attendant utilities watertight and capable of resisting the effects of the base flood. The building design shall take into account flood velocities, duration, rate of rise, hydrostatic and hydrodynamic forces, the effects of buoyancy, and impacts from debris or ice. Structural dry floodproofing measures shall be operable without human intervention and without an outside source of electricity. Levees, berms, floodwalls, and similar building protection measures are forms of dry floodproofing which are not structural dry floodproofing.
substantial damage: Damage of any origin sustained by a building in a floodplain whereby the cumulative percentage of damage during a 5 year period equals or exceeds 50 percent of the market value of the building before the damage occurred, regardless of actual repair work performed. The market value of volunteer labor and materials must be included in this determination.
substantial improvement: Any repair, reconstruction, rehabilitation, addition, or other activity to a building in a floodplain taking place during a 5 year period in which the cumulative project cost equals or exceeds 50 percent of the market value of the building before the improvement or repair is started.
Substantial improvement is considered to begin when the first alteration of any wall, ceiling, floor or other structural part of the building commences, whether or not that alteration affects the external dimensions of the building.
Substantial improvement includes:
A. The cost to repair a building that has incurred repetitive loss or substantial damage, regardless of the actual repair work performed; and
B. The cost of proposed maintenance of existing buildings; but
Substantial improvement does not include:
A. The cost of any maintenance of existing buildings completed within the previous 5 year period as a stand-alone project that did not require a building permit; or
B. The cost of any project to improve a building to comply with existing State or local health, sanitary, or safety code specifications, which are solely necessary to assure safe living conditions; or
C. The cost of any alteration of a historic structure, provided that the alteration will not preclude the structure’s continued designation as a historic structure.
sub-watershed: A sub-section of a larger watershed. For the purpose of this Ordinance, sub- watersheds would include the tributary areas of named streams and lakes within a given watershed (i.e. Rush, Lawrence, and Mokeler Creeks are sub-watersheds within the Piscasaw Watershed).
temporary erosion control: Erosion control measures used to control soil erosion and sedimentation during the construction phase of a development.
temporary IWMC impact: An IWMC impact that would result in a short-term loss of IWMC function. Temporary IWMC impacts shall not result in a permanent conversion of wetland to non-wetland. Temporary IWMC impacts shall not include relocation of an IWMC, or conversion of a vegetated community to open water. Additionally, for the IWMC impact to be considered temporary: soil profiles shall be restored to a similar pre-disturbance condition and elevation; vegetative communities shall be restored to the same or higher quality and function; and the restoration must be completed within 1 year of the disturbance. The Enforcement Officer shall make the determination as to whether an IWMC impact is considered a temporary IWMC impact.
TR-20: Technical Release 20 is a hydrograph producing hydrology computer model created by the NRCS.
TR-55: Technical Release 55 (NRCS, June 1986) is a document that presents simplified procedures for estimating runoff and peak discharges in small watersheds.
transition section: Reaches of the stream where water flows from a narrow cross-section to a wide cross-section and vice-versa.
travel trailer: See recreational vehicle or travel trailer.
tributary area: All of the land surface that contributes runoff to a given point.
urban area: The urban area designation within non-designated floodways shall be determined by IDNR/OWR. In flood prone areas, any densely developed residential, commercial or other non-residential land uses in which the U.S. Department of Commerce, Census Bureau (USCB) census block or tract contains a population density of at least 2,500 people, at least 1,500 of which reside outside institutional group quarters or as approved by the Enforcement Officer. Urbanized Areas and Urban Clusters, as defined by the USCB,
are subsets of urban areas. A map of all urban areas of the county can be found on the USCB website: http://tigerweb.geo.census.gov/tigerweb/.
USGS Regression Equations: Equations developed by the USGS and approved by IDOT for estimating the peak runoff from a watershed for a given flood frequency.
variance: A grant of relief by a community from the requirements of this Ordinance.
violation: The failure of a structure or other regulated development to be fully compliant with this Ordinance. A structure or other regulated development without the elevation certificate, other certifications, or other required evidence of compliance is presumed to be in violation until such time as that documentation is provided.
water dependent facilities: Structures or facilities relating or requiring access to the water or shoreline. Examples include shoreline protection, pumping and boating facilities and improvements.
waters: A subset of the definitions of the WOTUS and IWMC. Waters are areas that are normally inundated by surface water, such as lakes, ponds, and streams (including intermittent streams).
Waters of the United States (WOTUS): Those areas that are under the regulatory jurisdiction of the USACE.
watershed: A geographic area that collects, concentrates and contributes stormwater runoff to a given point on a waterway. The major watersheds in McHenry County, which are shown in Appendix 9, are:
A. Piscasaw Creek,
B. Nippersink Creek,
C. Kishwaukee River,
D. Upper Fox River,
E. Lower Fox River, and
F. Coon Creek.
watershed benefit: A decrease in flood damages created by installation of the stormwater management system. The benefit must be beyond the benefit provided by meeting the minimum requirement of this Ordinance.
watershed benefit measure : A Natural Resources Conservation Service (NRCS) Conservation Practice, or other approved practice, used to mitigate the adverse stormwater related effects of development. Measures include practices that: stabilize swales, agricultural ditches and streams; reconnect channels and wetlands to the floodplain; create or enhance wetlands, buffers and riparian areas; improve and preserve natural upland areas such as prairies and forest stands; and filter or remove pollutants from impervious areas or agricultural practices. Examples of allowable NRCS Conservation Practices include: bioreactors, channel bed stabilization, constructed wetland, contour buffer strips, drainage water management plan implementation, filter strips, grassed waterway, riparian forest buffer, riparian herbaceous cover, saturated buffers, streambank and shoreline protection, stream habitat improvement and management, wetland creation, wetland enhancement, and wetland restoration.
watershed plan: A study and evaluation of the stormwater management and/or floodplain management needs and capabilities of a watershed or sub-watershed.
Watershed Specific Area Development: Regulated development that is partially or completely located in a watershed or sub-watershed, for which additional or more restrictive standards have been adopted by MCSC or a Certified Community, based on the recommendations of a watershed plan.
wet bottom detention facility: A wet detention facility is designed to maintain a permanent pool of water after the temporary storage of stormwater runoff.
wet floodproofing: Protection from flood damage according to current FEMA guidelines by using flood damage-resistant materials below the FPE and elevating other items above the FPE. Wet floodproofing measures are among the floodproofing measures described in the following FEMA publications: Wet Floodproofing Requirements for Structures Located in Special Flood Hazard Areas (FEMA TB 7-93), Engineering Principles and Practices for Retrofitting Flood-Prone Residential Structures (FEMA P-259), Homeowner’s Guide to Retrofitting (FEMA P-312), Selecting Appropriate Mitigation Measures for Floodprone Structures (FEMA 551), Protecting Building Utilities from Flood Damage (FEMA 348), Reducing Damage from Localized Flooding (FEMA 511), Non-Residential Floodproofing – Requirements and Certification (FEMA TB 3), and Floodproofing Non-Residential Structures (FEMA 102).
wetland: A subset of the definitions of the WOTUS and IWMC. Wetlands are land that is inundated or saturated by surface or ground water at a frequency and duration sufficient to support, under normal conditions, a prevalence of vegetation adapted for life in saturated soil conditions (known as hydrophytic vegetation). A wetland is identified based upon the three attributes: 1) hydrology, 2) soils and 3) vegetation as mandated by the current Federal wetland determination methodology.
wetland creation: The introduction of wetlands to an area where none existed historically.
Wetland and Waters Development: Regulated development located partially or completely within WOTUS or IWMC.
wetland enhancement: The improvement in wetland functional value of an area currently meeting the technical definition of a wetland.
wetland mitigation banking: The process of purchasing “credits” from a financial institution established by a third party to compensate for permitted losses.
wetland restoration: The re-introduction of wetlands to an area where wetlands existed historically, but not prior to the mitigation activity.
wetland restoration activities: Those restoration activities in wetlands or adjacent buffer areas determined to be necessary and beneficial to the preservation, maintenance, or restoration of wetland plant communities, wildlife habitat and ecosystems native to McHenry County.
wetland specialist: A person complying with A, B, and C as follows:
A. Provide a signed statement of qualifications to MCSC demonstrating the minimum requirements of B and C have been met. The signed statement will be considered evidence of qualification.
B. Completion of the USACE Wetland Delineation Certification Program or equivalent course and meet one of the following.
(1) Registered Professional Wetland Scientist (PWS) from the Society of Wetland Scientists; or
(2) Minimum of a Bachelor’s Degree in an Earth Science or Biologic Science and at least one of the following:
a. Three years (cumulative) full-time experience in the Upper Midwest region on wetland related projects; or
b. The completion of 100 wetland delineations in the upper Midwest; or
c. A minimum of 300 hours spent in field review of wetlands in the Upper Midwest.
C. A minimum of 24 work-related professional development hours shall be obtained every three years. Documentation shall be self-monitoring and shall be provided to MCSC upon request.
Zone A: Areas subject to inundation by the 1 percent-annual chance flood event generally determined using approximate methodologies. Because detailed hydraulic analyses have not been performed, no BFEs or flood depths are shown. Mandatory flood insurance purchase requirements and Flood Hazard Area Performance Standards apply.
Zone AE: Areas subject to inundation by the 1 percent-annual chance flood event determined by detailed methods. BFEs are shown. Mandatory flood insurance purchase requirements and Flood Hazard Area Performance Standards apply.
Zone AH: Areas subject to inundation by 1 percent-annual-chance shallow flooding (usually areas of ponding) where average depths are between one and three feet. BFEs derived from detailed hydraulic analyses are shown in this zone. Mandatory flood insurance purchase requirements and Flood Hazard Area Performance Standards apply.
Zone AR: Areas that result from the decertification of a previously accredited flood protection system that is determined to be in the process of being restored to provide base flood protection. Mandatory flood insurance purchase requirements and Flood Hazard Area Performance Standards apply.
Zone AO: Areas subject to inundation by 1 percent-annual-chance shallow flooding (usually sheet flow on sloping terrain) where average depths are between one and three feet. Average flood depths derived from detailed hydraulic analyses are shown in this zone. Mandatory flood insurance purchase requirements and Flood Hazard Area Performance Standards apply.
(Ord. O-2020-09-15, passed 9-15-2020; Ord. O-202009-10-030, passed 9-15-2020)