§ 151.146  PERFORMANCE STANDARDS FOR ALL DEVELOPMENT.
   Development subject to the site development regulations shall comply with all applicable performance standards of this section. The performance standards for all development shall be considered in site planning and appropriately addressed in the drainage plan component of subdivisions, annexation agreements, preliminary plats, final plats, re-plats, manufactured home parks and planned unit developments. All plans, reports, and calculations required pursuant to these regulations shall fully demonstrate a proposed development’s compliance with the following performance standards.
   (A)   Plat and site plans.
      (1)   To address the runoff volume reduction requirements of subsection (D), all streets, blocks, lots, deed- or plat-restricted areas, parks, and other public grounds shall be located and designed in such a manner as to preserve and utilize natural wetlands, flood-prone areas, channels, and best management practices and undisturbed native soil/plant areas utilized to meet the runoff volume reduction requirements.
      (2)   All plats and engineering plans shall show the base flood elevation and regulatory floodway limits, if applicable. They shall also include a signed statement by a registered professional engineer that accounts for changes in the drainage of surface waters in accordance with the Plat Act (765 ILCS 205/2).
      (3)   All plats and site plans that border on or include public bodies of water as defined by the Illinois Department of Natural Resources, Office of Water Resources and listed in Appendix I shall be submitted by the applicant to the Illinois Department of Natural Resources, Office of Water Resources for review and approval.
      (4)   Soil erosion and sediment control measures and stormwater management facilities shall be functional before general construction begins. Where development of a site is to proceed in phases, the soil erosion and sediment control measures needed for each phase shall be functional before the construction of that phase begins.
      (5)   All stormwater management systems within the ownership parcel shall be contained within an appropriately sized and located deed restriction or plat restriction. Stormwater management systems that service a single parcel or two parcels of property may be exempted from this requirement upon approval of the Planning, Building and Development Director.
      (6)   Modifications to a deed or plat restriction for the stormwater management system shall be approved by the Planning, Building and Development Director. Lot line modifications shall require Plat Committee approval.
      (7)   Pursuant to state law, a property owner of a parcel being subdivided adjacent to a state or county road right-of-way shall notify the proper highway authority in writing of the proposed subdivision, and request that the proper highway authority provide the amount of additional capacity in any stormwater detention facility to be constructed in the subdivision for the future availability of the highway authority for meeting stormwater detention requirements of any future public construction on the highway.
   (B)   Runoff calculations.
      (1)   For tributary drainage areas of 100 acres or more in area and for the determination of detention and depressional storage requirements, a Lake County Stormwater Management Commission-approved hydrograph-producing runoff calculation method shall be used. Appendix J also may be used, when appropriate and upon approval of the Planning, Building and Development Director, for determination of detention storage volumes.
      (2)   The Rational Method may be used to calculate discharges for areas of less than 100 acres. The Rational Method shall not be used to determine detention or depressional storage requirements.
      (3)   Rainfall data obtained from the Lake County Stormwater Management Commission (presented in Appendix K) shall be used for rainfall volume, storm distribution, return frequency, and event duration.
      (4)   Runoff calculations for all off-site drainage areas shall be based on anticipated future land use conditions or existing land use conditions, whichever yields the greater runoff. Anticipated future land use conditions will be based on future land use and existing storage facilities. Future detention facilities may be used for anticipated future land use conditions if approved by the Lake County Stormwater Management Commission Chief Engineer or, for tributary drainage areas less than 100 acres if approved by the Planning, Building and Development Director. Existing land use conditions will be based on existing land use and existing storage facilities. For each frequency storm event, runoff calculations will be based on the critical duration, for all durations presented in Appendix K.
      (5)   Existing depressional storage volume shall be maintained and the volume of detention storage provided to meet the requirements of this chapter shall be in addition to the existing storage.
      (6)   For determination of soil runoff characteristics, areas of the development that are hydrologically disturbed and compacted shall be changed to that soil type’s and highest runoff potential/soil group classification. Soil groups that are not hydrologically disturbed will retain their current runoff characteristics. Areas that are deed- or plat-restricted for native planting areas may be determined to have lower runoff characteristics, and may be taken into account when meeting the runoff volume reduction requirements of this chapter.
   (C)   Release rates and discharges.
      (1)   Unless otherwise specified in a county-adopted basin plan, floodplain study, or Appendix L, the detention volume required shall be calculated using a rating curve based on maximum release rates of 0.04 cubic feet per second, per acre for the two-year, 24-hour storm event, nor 0.15 cubic feet per second, per acre for the 100-year, 24-hour storm event. The release rate requirements shall apply to the hydrologically disturbed area of the ownership parcel unless the Planning, Building and Development Director determines that specific locations of the ownership parcel have unique circumstances such that the release rate shall apply to a broader or smaller area. The release rate requirements shall only apply to the developments listed in § 151.145(B)(6).
      (2)   All concentrated stormwater discharges must be conveyed into a maintainable outlet with adequate downstream stormwater capacity (as defined in § 151.271) and will not result in increased flood and drainage hazard. An existing channel, storm sewer or overland flow path is said to have adequate downstream capacity when it can be shown to accommodate up to and including the 100-year stormwater runoff without increasing property damage to the adjacent property or to a point downstream known to be a restriction causing significant backwater.
      (3)   The design of stormwater drainage systems shall not result in the interbasin transfer of drainage, unless no reasonably feasible alternative exists. The Planning, Building and Development Director may also allow interbasin transfer if the transfer relieves a known drainage hazard and there is adequate downstream stormwater capacity.
      (4)   There shall be a minimum of one foot of freeboard above the base flood elevation on all detention/retention basins.
      (5)   Watershed-specific release rates are tabulated in Appendix L.
      (6)   The combined release from the detention facility outlet and the outlet designed to meet wetland hydrology requirements of subsection (M)(7) shall not exceed either the two- or 100-year allowable release rates, respectively. The wetland hydrology requirement or minimum outlet restrictor size may take precedence over the allowed release rate, provided there is adequate downstream capacity as determined by the Planning, Building and Development Director.
      (7)   The applicant shall prohibit illicit discharges generated during the development process from entering into the stormwater management system. Discharges of stormwater from a development site shall be in conformance with the soil erosion and sediment control practices contained in §§ 151.145 through 151.154 of this chapter.
   (D)   Runoff volume reduction (RVR).
      (1)   Applicants shall choose a strategies that minimize stormwater runoff volumes and addresses water quality impairments. The site development plan shall incorporate stormwater infiltration, evapotranspiration, reuse, or other methods, into the project. The applicant shall use appropriate green infrastructure techniques and best management practices to reduce runoff volume, according to the following hierarchy, in order of preference, in preparing a stormwater management plan:
         (a)   Preservation and enforcement of the stormwater management benefits of the natural resource features of the development site (e.g., areas of Hydrologic Soil Groups A and B, floodplains, waters of the United States, isolated waters of Lake County, channels, drainageways, prairies, savannas, and woodlands);
         (b)   Minimization or disconnection of impervious surfaces;
         (c)   Enhancement of the infiltration and storage characteristics of the development site using appropriate best management practices;
         (d)   The use of open channels with native vegetation to convey stormwater runoff;
         (e)   Structural measures that provide water quality and volume reduction;
         (f)   Structural measures that provide only volume reduction or other rainwater harvesting practices;
         (g)   Measures that provide water quality and quantity control; and
         (h)   Measures that provide only quantity control.
      (2)   (a)   Runoff volume reduction (RVR), Quantitative Standard. The minimum RVR quantitative standard shall be the volume achieved utilizing applicable RVR Credits, as determined by the applicant and approved by the Planning, Building and Development Director, based on the maximum extent practicable, for the following development. The term “new” for the RVR Quantitative Standard refers to impervious surface created after April 1, 2009.
         (b)   Minor and Major Development that result in at least one acre hydrologic disturbance and more than 0.5 acre of new impervious surface area; Redevelopment of previously developed sites that result in at least one acre hydrologic disturbance:
            1.   RVR implementation criteria.
               a.   Runoff volume reduction quantity shall be implemented with appropriate methods, as approved by the Planning. Building and Development Director, which may include the following: best management practices: green infrastructure: detention facilities: and preservation or enhancement of natural streams, wetlands, and areas with deed restricted native vegetation.
               b.   Best management practices, and the portion of the detention facility designed to meet this provision, shall be designed to dewater the RVR quantity in no greater than 96 hours. The applicant shall provide infiltration rate information for each RVR practice. The use of an under drain system may be incorporated into the design in order to achieve the required draw down time. Under drain systems shall be designed to dewater the RVR quantity in not less than 48 hours.
            2.   RVR credits. The following credits may be used alone or in combination to meet the RVR quantity requirement:
               a.   Detention facility credit. Up to 50% of the RVR quantity may be provided within the portion of the detention facilities that have been designed to meet this standard. The volume provided to meet this provision shall be below the elevation of the primary outlet for the RVR portion of the facility.
               b.   Native vegetation cover credit. Up to 100% of the reduced two-year, 24-hour runoff volume achieved with native vegetation in deed or plat restricted areas (e.g., compensatory storage and buffer areas) as described in Soil Runoff Characteristics (subsection (B)(6) above) and Linear Water Bodies (subsection (H)(6) below).
               c.   Isolated wetland hydrology credit. A maximum of 100% of the existing two-year. 24-hour runoff volume to a preserved IWLC if the Wetland Hydrology (subsection (M)(7) below) and Water Quality Treatment (subsection (H)(4) below) requirements are met.
               d.   Water quality treatment credit. Up to 100% of the volume utilized to meet the Water Quality Treatment Volume (subsection (H)(4) below).
               e.   Off-site RVR credit. RVR practices may be provided on off-site, localized properties that are within the same basin. Deed or plat restrictions shall be obtained and recorded on off-site properties to assure perpetual operation and maintenance of RVR facilities.
               f.   Best management practice and green infrastructure credits. Up to 100% of the volume within the practices designed to meet this standard.
   (E)   New stormwater facilities.  The design of all new stormwater facilities shall comply with the following standards:
      (1)   All new stormwater infiltration, retention and detention basins shall be provided with an emergency overflow structure capable of passing the critical duration base flood inflow rate without damages to downstream structures or property;
      (2)   (a)   New stormwater infiltration, retention and detention basins required to meet a development’s discharge requirements shall be designed to bypass off-site tributary flow from channels unless approved by the Planning, Building and Development Director;
         (b)   All parcels within the established flood table land’s elevation criteria of a detention facility design high water level shall be protected from flooding as follows:
            1.   For detention facilities with less than 100 acres of tributary area, all structures in parcels containing or adjoining the facility shall have a lowest adjacent grade a minimum of one foot above the design high water elevation within the emergency overflow structure.
            2.   For detention facilities with greater than or equal to 100 acres of tributary area, all structures in parcels containing or adjoining the facility shall meet the requirements of § 151.149(H) at an elevation two feet above the design high water elevation within the emergency overflow structure. New residential structures may have the lowest floor below this elevation if structurally dry flood-proofed to at least two feet above the design high-water elevation within the emergency overflow structure.
      (3)   Single pipe outlets shall have a minimum inside diameter of 12 inches. If design release rates call for smaller outlets, a design that minimizes the possibility of clogging shall be used. Minimum outlet restrictor size shall be four inches, provided there is adequate downstream capacity. Detention volumes and corresponding high water level required for a development shall be determined by using the appropriate release rates specified in subsection (C) regardless of a minimum outlet restrictor size;
      (4)   Outlet control structures shall be designed as simply as possible and shall operate automatically. They will be designed to limit discharges into existing or planned downstream channels or conduits so as not to exceed predetermined safe capacities and not in excess of flows which would have occurred with the land in its natural, undeveloped condition.
      (5)   The approach slopes of the basin shall conform as closely as possible to natural land contours. Regrading is preferable if necessary to keep the slopes under 10%. Erosion control measures shall be provided as well as devices or measures to ensure public safety;
      (6)   Any work involving the construction, modification or removal of a dam as defined in 17 Ill. Adm. Code 3702 (Rules for Construction of Dams) shall obtain an Illinois Department of Natural Resources, Office of Water Resources Dam Safety permit, or a letter stating that a permit is not required, prior to the start of the activity;
      (7)   With the approval of the Planning, Building and Development Director, stormwater retention and detention basins may be constructed in the regulatory floodplain. Lost floodplain storage volume due to fill, structures, and detention storage shall be replaced with compensatory storage in accordance with § 151.149. No credit may be taken for storage volume below the base flood elevation. (See also § 151.147.);
      (8)   No new stormwater detention or retention basin shall be located closer than ten feet plus one and one-half times the depth of the basin to the ultimate right-of-way of any public road, without the written permission of the highway authority having jurisdiction over the right-of-way. Likewise, the toe of any berm used to create a basin shall be a minimum of ten feet from the ultimate right-of-way;
 
COMMENTARY:
Best management practices are presented in the Lake County Stormwater Management Commission’s Technical Reference Manual.
 
      (9)   For basins designed without permanent pools (dry bottom type), provisions must be incorporated to facilitate interior drainage, to include positive grades to outlet structures (bottom of basins must be a minimum of 2% grade), longitudinal and transverse grades to perimeter drainage facilities, or the installation of sub-surface drains. Wherever practical the interior drainage shall be provided over non-erosive vegetative surfaces. When vegetation cannot be established, a rip-rap or concrete swale or underdrain shall be provided from the inlet structure to the outlet structure. Multi-purpose features may be designed as part of dry bottom detention facilities; however, the features must be designed to serve only secondary purposes for recreation, open space, or other uses which will not be adversely affected by occasional or intermittent flooding;
      (10)   For basins designed with permanent pools (wet bottom type):
         (a)   The minimum normal depth of water before the introduction of excess stormwater shall be four feet;
         (b)   If fish are stocked, at least one-fourth of the area of the permanent pool must have a minimum depth of 12 feet;
         (c)   For emergency purposes, cleaning or shoreline/buffer maintenance, facilities shall be provided or plans prepared for the use of auxiliary equipment to permit emptying and drainage;
         (d)   Approach slopes shall be at least 6:1 but not more than 3:1 and shall be at least four feet wide and shall slope towards the basin. A minimum eight-foot wide safety shelf with a maximum depth of three feet below normal water level sloped back towards the shoreline. The side slopes shall be of non-eroding material with a slope of 1:1 or less. Alternate designs for side slopes may be considered under special circumstances and when approved by the Planning, Building and Development Director; and
         (e)   Sediment storage shall be provided in all detention/retention basins. The amount of sediment storage capacity shall be determined by the Planning, Building and Development Director based on size of the development, soil types, construction methods, basin design, and other relevant factors.
      (11)   For basins designed as a wetland type basin, provisions must be incorporated to facilitate interior drainage, to include positive grades to outlet structures, longitudinal and transverse grades to perimeter drainage facilities, or the installation of sub-surface drains. A basin plan shall be prepared for the establishment and maintenance of the wetland vegetation. Multi-purpose features may be designed as part of dry bottom detention facilities; however, the features must be designed to serve only secondary purposes for recreation, open space, or other uses which will not be adversely affected by occasional or intermittent flooding;
      (12)   Detention storage may be met in total or in part by detention on flat roofs. Details of designs to be included in the building permit application shall include the depth and volume of storage, details of outlet devices and downdrains, elevation of overflow scuppers, design loadings for the roof structure and emergency overflow provisions. Direct connection of roof drains to sanitary sewers is prohibited;
      (13)   Paved parking lots may be designed to provide temporary detention storage of stormwater on all or a portion of their surfaces. Outlets will be designed so as to slowly empty the stored waters, and the depth of storage must be limited to not greater than six inches so as to prevent damage to parked vehicles;
      (14)   All or a portion of the required detention storage may be provided in underground facilities with the approval of the Planning, Building and Development Director. No detention storage may be provided in or under the ultimate right-of-way of any public road;
      (15)   On-stream detention.
         (a)   All on-stream detention shall provide a Detention Volume Safety Factor as follows:
            1.   The Detention Volume Safety Factor is applied to the volume of on-stream detention necessary to meet the Watershed Development Ordinance site requirements.
            2.   The Detention Volume Safety Factor is equal to one plus 0.05 times the ratio of off-site tributary area to on-site tributary area.
            3.   The maximum Detention Volume Safety Factor shall be 1.5.
         (b)   No on-stream detention shall be allowed with an off-site to on-site tributary area greater than 10:1 except for development providing a watershed benefit.
         (c)   On-stream detention shall not be permissible if the tributary drainage area is greater than 640 acres except for detention that provides a watershed benefit.
         (d)   The release rate shall be 0.04 cubic feet per second per acre of the total tributary (on-site and off-site) at the elevation created by impoundment of the on-site two-year storm volume plus the Detention Volume Safety Factor, and 0.15 cubic feet per second per acre of the total tributary area (on-site and off-site) at the elevation created by impoundment of the on-site 100-year storm volume plus the Detention Volume Safety Factor. The release rate shall be calculated using the 24-hour storm event. This release rate calculation shall be used unless other site conditions warrant further analysis and modification from this standard or unless watershed specific release rates have been adopted as listed in Appendix L.
         (e)   On-stream detention shall provide water quality treatment. One of the following two methods shall be used:
            1.   A wet detention facility with a minimum permanent pool volume equal to the calculated sediment volume accumulated over a one-year period for the entire upstream watershed and an average normal water depth of at least four feet. The facility shall also have a live storage volume that, at a minimum, equals the water quality treatment standards of subsection (H)(4) for the development site; or
            2.   A separate off-line siltation basin with a volume meeting the water quality treatment standards of subsection (H)(4) for the tributary drainage area to the sediment basin.
         (f)   Impoundment of the stream as part of on-stream detention shall be designed to allow the migration and movement of present or potentially present indigenous species, which require access to upstream areas as part of their life cycle. The impoundment shall not cause or contribute to the degradation of water quality or stream aquatic habitat.
         (g)   Compensatory storage require-ments shall be satisfied.
         (h)   No on-stream detention shall be allowed in areas designated as an exceptional functional value wetland.
      (16)   An access easement wide enough to allow the passage of construction traffic must be provided to any detention basin not adjacent to a public right-of-way;
      (17)   Impounding berms or walls for stormwater retention and detention facilities shall be designed and constructed to withstand all expected forces, including but not limited to erosion, pressure and uplift. The applicant shall submit material and compaction design specifications for earthen impoundments and provide as-built information verifying that the construction condition meets the design requirements. Impounding berms or walls shall be represented on the design plans and signed and sealed by a registered professional or structural engineer;
      (18)   The top of the impounding structure shall be a minimum of one foot above the design high water level within the emergency overflow structure based on subsection (E)(1) above; and
      (19)   All stormwater facilities, when determined applicable by the Planning, Building and Development Director, shall be provided with features for maintenance and emergency ingress and egress capability.
   (F)   Existing stormwater facilities.
      (1)   Existing lakes, ponds or stormwater basins may be utilized to provide for the stormwater detention required by this section, provided that the storage capacity of the existing basin and its ability to function to provide for the intent of the regulations of this section shall be verified to the satisfaction of the Planning, Building and Development Director. In these cases, the existing basin shall comply with all of the design and engineering standards for new stormwater basins, as established in subsection (E), except when the Planning, Building and Development Director finds that the modification of the existing basin to comply with the standards of this section would not be practical nor desirable, and provided that the deviation from the standards of this section will not serve to compromise the overall intent of this section.
      (2)   Wetlands may be utilized to provide for the stormwater detention required by this section, provided that the existing depressional storage volume of the wetland is maintained and that the volume of detention storage provided to meet the requirements of this section is in addition to the existing storage volume. The use of wetlands for stormwater detention purposes is subject to the following standards.
         (a)   If the wetland will be excavated or if the proposed outlet structure elevation is set above the existing normal water elevation of the wetland, the proposed basin shall comply with all of the design and engineering standards for new stormwater basins established in subsection (E) (except when the Planning, Building and Development Director finds that the modification of the wetland to comply with the standards of this section would not be practical nor desirable, and provided that the deviation from the standards of this section will not serve to compromise the overall intent of this section). The use of wetlands for stormwater detention purposes may require U.S. Army Corps of Engineers approval (see subsection (M)(1) below).
         (b)   If the wetland will not be excavated and if the proposed outlet structure elevation is set at the existing normal water elevation of the wetland, the proposed basin shall not be required to comply with the design and engineering standards for new stormwater basins, as established in subsection (E) above. The use of wetlands in this manner may require U.S. Army Corps of Engineers approval.
         (c)   A management plan for maintaining the existing storage volume shall be prepared.
   (G)   Joint development/use of stormwater management facilities.
      (1)   Stormwater management facilities may be planned in coordination by two or more developments or land owners as long as flood and/or stormwater hazards are not increased at intervening locations, and shall be encouraged by the county wherever feasible. In these cases, a maintenance agreement, approved by the Planning, Building and Development Director, shall be established between the developments or land owners and recorded with the Lake County Recorder (see subsection (I) below).
      (2)   In the event that an existing stormwater management facility is, in whole or in part, under the sole and exclusive control of a separate individual or governmental agency, the Planning, Building and Development Director shall not permit the use of the existing facility unless the individual or governmental agency having the sole and exclusive control grants its permission for the use of the existing facility. Permission granting the use of the stormwater management facility shall be in writing and must be presented to the Planning, Building and Development Director.
   (H)   Stormwater conveyance systems.
      (1)   Storm sewers and swales.
         (a)   The ten-year design storm shall be used as a minimum for the design of storm sewers, swales, and appurtenances. Storm sewers shall have a minimum diameter of 12 inches, with the exception that storm sewers servicing a single parcel may be excused from this requirement upon approval of the Planning, Building and Development Director. Storm sewer design analysis shall be calculated under full flow conditions, unless prior approval from the Planning, Building and Development Director is received for an alternate flow condition (e.g., pressure flow).
         (b)   The development shall not connect to sanitary sewers or to existing agricultural stormwater management systems (tiles) as an outflow for the stormwater management system. Field tile systems disturbed during the process of land development must be reconnected by those responsible for their disturbance unless the approved drainage plan includes provisions for their relocation.
         (c)   All storm sewers shall be located in a public road right-of-way or drainage easement of sufficient size to maintain or reconstruct the sewer. A covenant, running with the land, shall be recorded with the easements describing the maintenance responsibilities in the easements (see subsection (I) below). Prior to the construction of any storm sewer within an existing public road right-of-way, written permission must be obtained from the highway authority having jurisdiction over the right-of-way.
         (d)   All on-site stormwater management systems shall be designed and constructed to withstand the expected velocity of flow from all events up to the base flood without erosion. Stabilization adequate to prevent erosion shall be provided at the inlets and outlets of all pipe transitions and paved channels.
         (e)   All swales utilized as part of the stormwater management system for a development shall be located within a deed-restricted or plat-restricted area of sufficient size to maintain or reconstruct the swale.
         (f)   All swales must be a minimum 2% grade unless the Planning, Building and Development Director determines that the existing site conditions will prohibit that grade.
         (g)   Surface outflows onto adjoining properties shall be designed to release as sheet flow using level spreader trenches unless alternative designs are approved by the Planning, Building and Development Director.
         (h)   For agricultural drain tiles (tiles) the following provisions shall apply.
            1.   Field tile systems disturbed during the process of development shall be reconnected by those responsible for their disturbance unless the approved drainage plan includes provisions for these.
            2.   Observation structures, or similar maintenance and inspection access structures, shall be installed within the development at the suitable points of ingress and egress.
            3.   The applicant shall notify adjoining downstream property owners in writing of any proposed stormwater facility outlet location and design. The development design shall utilize, where practical and approved by the Planning, Building and Development Director, outflow locations that have an existing tile leaving the development site. A subsurface connection to the tile shall be constructed as a low flow outlet. A surface outlet shall be designed for the development site outflows based on the assumption the downstream tile will cease to function.
            4.   Drain tiles within the disturbed portions of the ownership parcel shall be replaced or intercepted and connected into the proposed stormwater management system or a bypass. The system or bypass shall be of an equivalent size.
            5.   Drain tiles located within an ownership parcel may be removed or disabled provided that a maintainable outlet exists or is installed to prevent flood damages to off-site properties.
            6.   If the development stormwater management system depends on existing drain tiles for stormwater conveyance or water surface elevation control, a maintainable outlet is required.
            7.   The locations for existing drain tiles within the ownership parcel shall be defined using the Subsurface Drainage Inventory. Recorded deed or plat restrictions shall be provided for all existing and replaced drain tiles within the ownership parcel which are part of the stormwater management system. Drain tiles that service a single parcel of property may be excused from this requirement upon approval of the Planning. Building and Development Director.
            8.   The maintenance plan per § 151.145(F)(2)(f)3. shall include the type and frequency of maintenance for all existing and replaced drain tiles within the ownership parcel which are part of the stormwater management system.
      (2)   Sump pump and drain tile discharges.
         (a)   The connection of sump pumps, roof drain tile systems or any other new drain tile line, or the discharge of groundwater or stormwater into sanitary sewers shall not be permitted.
         (b)   Sump pumps, roof drain tile systems or any other new drain tile line shall discharge into any channel that has adequate downstream capacity, other than the open drainage system (e.g., a roadside ditch) of a public road right-of-way. When there exists no channel with adequate downstream capacity, other than the open drainage system of a public road right-of-way, sump pumps, roof drain tile systems, or any other new drain tile line may discharge into the open drainage system of a public road right-of-way. When existing conditions permit, however, the discharge point shall be no closer than 20 feet from the road right-of-way and water from the discharge point shall flow to the right-of-way via a non-channelized, non-erosive, non-impervious surface (i.e., sheet flow over grass). The discharge from a sump pump, roof drain tile system, or any other new drain tile line shall be conveyed in a manner which does not impact adjoining property owners.
         (c)   The direct connection of sump pumps, roof drain tile systems, or any other new drain tile line into a closed drainage system (e.g., a storm sewer), designed to accommodate the stormwater or groundwater discharges, is encouraged within new developments. The connection of sump pumps, roof drain tile systems, or any other new drain tile line into an existing closed drainage system shall only be permitted when the ability of the existing drainage system to accommodate the stormwater or groundwater discharges is verified by the applicant.
      (3)   Overland flow paths.
         (a)   Generally. All areas of development must provide an overland flow path that will pass the base flood flow without damage to structures or property. If the upstream drainage area is less than 20 acres, a storm sewer pipe and inlet systems sized for the base flood can be constructed in lieu of providing an overland flow path.
         (b)   Flow rate.  The flow rate for the base flood shall establish overland flow path limits, and it shall include all on-site and off-site tributary areas in accordance with subsection (B) above.
         (c)   Deed of plat - restricted area. All proposed overland flow paths shall be located within a deed-restricted or plat-restricted area of sufficient size to maintain or reconstruct the overland flow path. The overland flow path shall be protected from any activity, such as fencing, landscaping, or storage shed placement, which could impair its function. This protection shall be established through a properly recorded deed or plat restriction.
         (d)   Less than 20 acres.  For overland flow paths with less than 20 acres tributary area, all structures on a parcel containing or adjoining to an overland flow path or other high water level designation shall have a lowest adjacent grade a minimum of one-half foot above the design high water.
         (e)   Over 20 acres. For overland flow paths with greater than or equal to 20 acres tributary drainage area but less than 100 acres, all structures on parcels containing or adjoining to an overland flow path or other high water level designation shall have a lowest adjacent grade a minimum of one foot above the design high water elevation.
         (f)   Public health protection.
            1.   No development in or adjacent to an overland flow path shall include locating or storing chemicals, explosives, buoyant materials, animal wastes, fertilizers, flammable liquids, pollutants, or other hazardous or toxic materials below one foot above the design high water elevation of the overland flow path.
            2.   New and replacement water supply systems, wells, and sanitary sewer lines may be permitted providing all manholes or other above-ground openings located below the design high water elevation of the overland flow path are watertight.
            3.   On-site individual sewage disposal systems in or adjacent to an overland flow path shall be designed to avoid inundation by the base flood.
      (4)   Water quality treatment. Water quality treatment standards can be achieved by combining the Runoff Volume Reduction requirements in subsection (D) above and the following requirements. The following water quality requirements apply to developments that result in at least 0.5 acre of new impervious surface area, where “new” is defined in § 151.145(B)(6). The volume of runoff kept on-site to meet the Runoff Volume Reduction requirements of this chapter (subsection (D)(1) above) may be deducted from the required water quality treatment volume.
 
COMMENTARY:
Best management practices are presented in the Lake County Stormwater Management Commission’s Technical Reference Manual.
 
         (a)   Prior to discharging to waters of the United States, isolated waters of Lake County or adjoining property, development shall divert and detain at least the first 0.01 inch of runoff for every 1% of impervious surface for the “development with a minimum volume equal to 0.2 inches of runoff (e.g., 20% or less impervious = 0.2, 50% impervious = 0.5, 90% impervious = 0.9); or provide a similar level of treatment of runoff as approved by the Planning, Building and Development Director and consistent with best management practices.
         (b)   Where practical, stormwater shall discharge into the buffer area of a wetland, or water body rather than directly into the wetland, lake, or pond. The discharges shall enter the buffer as unconcentrated flow with appropriate energy dissipation measures to prevent erosion.
         (c)   A buffer shall be established between design normal and high water levels around stormwater management facilities constructed for water quality treatment to enhance treatment effectiveness. The buffer area planting plan shall use the Native Plant Guide for Streams and Stormwater Facilities in Northeastern Illinois, NRCS, et al., (as amended) as a minimum standard.
         (d)   Hydrocarbon (e.g., oil and grease) removal technology shall be required using a volume of one-half inch of runoff for the new impervious surface tributary area to each treatment device and meeting a minimum 70% removal rate for all development classified as follows:
            1.   Vehicle fueling and servicing facilities; and
            2.   Parking lots with more than 25 new stalls.
      (5)   Buffer areas.
         (a)   Buffer areas shall be required for all areas defined as either “waters of the United States” or “isolated waters of Lake County”. Buffer areas are divided into two types, linear buffers and water body buffers.
            1.   Linear buffers shall be designated along both sides of all linear water bodies meeting the definition of “waters of the United States”.
               a.   When the linear water body has a watershed greater than 20 acres but less than one square mile, the minimum buffer width shall be 50 feet on each side of the linear water body.
               b.   When the linear water body has a watershed greater than one square mile, the minimum buffer width shall be 30 feet on each side of the linear water body.
               c.   Linear exceptional functional value wetlands and streams with an Index of Biotic Integrity greater than 40 shall have a minimum buffer width of 100 feet on each side of the linear water body. (Initial IBI based on the Illinois Environmental Protection Agency’s Illinois Water Quality Report, biannual. A site specific IBI assessment may override this report.)
            2.   Water body buffers shall encompass all nonlinear bodies of water meeting the definition of either waters of the United States or isolated waters of Lake County. The buffer width shall be determined as follows:
               a.   For all water bodies or wetlands with a total surface area greater than one-third acre but less than one acre, a minimum buffer width of 30 feet shall be established;
               b.   For all water bodies or wetlands with a total surface area greater than or equal to one acre but less than two and one–half acres, a minimum buffer width of 40 feet shall be established; and
               c.   For all water bodies or wetlands with a total surface area greater than or equal to two and one-half acres, a minimum buffer width of 50 feet shall be established.
            3.   A buffer shall be established between design normal and high water levels around stormwater management facilities constructed for water quality treatment to enhance treatment effectiveness. The buffer area planting plan shall use the Native Plant Guide for Streams and Stormwater Facilities in Northeastern Illinois, NRCS, et al. (as amended) as a minimum standard.
         (b)   Nonlinear high-quality aquatic resources shall have a minimum buffer width of 100 feet.
         (c)   Areas having state or federal threatened and endangered species present or for Illinois Natural Area Inventory Sites, buffer widths may be modified upon approval of the Planning, Building and Development Director, to meet the terms and conditions specified during consultation with the Illinois Department of Natural Resources or United States Fish and Wildlife Service pursuant to state and federal laws and regulations.
         (d)   The buffer area for all water bodies meeting the definition of waters of the United States or isolated waters of Lake County shall extend from the ordinary high water mark. The buffer area for wetlands shall extend from the edge of the delineated wetland. A property may contain a buffer area that originates from waters of the United States or isolated waters of Lake County on another property.
         (e)   Features of the stormwater management system approved by the Planning, Building and Development Director may be within the buffer area of a development.
         (f)   Access through buffer areas shall be provided, when necessary, for maintenance purposes.
         (g)   All roadside drainage ditches, and excavated detention facilities in existence on August 10, 1999, borrow pits, quarries, and improvements to existing public road developments or alignments are exempt from buffer requirements.
         (h)   Stormwater discharges that enter a buffer shall have appropriate energy dissipation measure to prevent erosion and scour.
         (i)   All buffer areas shall be maintained free from development including disturbance of the soil, dumping or filling, erection of structures and placement of impervious surfaces except as follows.
            1.   A buffer area may be used for passive recreation (e.g., birdwatching, walking, jogging, bicycling, horseback riding and picnicking) and it may contain pedestrian, bicycle, or equestrian trails.
            2.   Structures and impervious surfaces (including trails, paths) may occupy a maximum of 20% of the buffer area, provided the runoff from the facilities is diverted away from the waters of the United States or Isolated Waters of Lake county or the runoff is directed to enter the buffer area as unconcentrated flow.
            3.   Utility maintenance, construction of stormwater facilities, and maintenance of stormwater facilities shall be allowed.
            4.   Boat docks, boathouses, and piers shall be allowed and the provisions of subsection (H)(5)(i)2. above shall not apply.
            5.   Buffer areas hydrologically disturbed by allowed construction or as part of a re-vegetation plan shall be re-vegetated using the Native Plant Guide for Streams and Stormwater Facilities in Northeastern Illinois, NRCS et al. (as amended), as a minimum standard.
         (j)   A minimum of a one-foot temporary construction buffer from the limits of the waters of the United States or isolated waters of Lake County shall be required unless the adjacent wetland is considered impacted or enhanced. The one-foot temporary construction buffer shall be marked by construction fencing (Illinois Department of Transportation Standard) and installed prior to the start of all other construction activities. All other construction activities, including soil erosion and sediment control features, shall take place on the non-wetland side of the construction fencing.
         (k)   Buffer averaging: the buffer width for a development site may be varied to a minimum of one-half of the buffer width required, upon approval of the Planning, Building and Development Director, provided that the total buffer area required is achieved adjacent to the waters of the United States or isolated waters of Lake County being buffered. The consultation process of the Illinois Department of Natural Resources or U.S. Fish and Wildlife Service may override the ability to average buffer areas upon approval of the Planning, Building and Development Director.
         (l)   Preservation of buffer areas shall be provided by deed or plat restriction.
         (m)   The buffer area of a development site may be subtracted from the water quality volume required.
      (6)   Linear water bodies.
         (a)   Linear water bodies are to be conserved (see § 151.071(G)).
         (b)   Appropriate uses:
            1.   For linear water bodies with a tributary drainage area of less than 20 acres, the establishment of any use permitted by the underlying zoning district is permitted in the linear water body, provided that provisions are made to pass the base flood flow without damage to structures or property.
            2.   For linear water bodies with a tributary drainage area of 20 acres or more, only the construction, modification, repair, or replacement of the uses listed below will be allowed in the linear water body, and provided that the uses will not cause an increase in flood heights for all flood events up to and including the base flood. The placement of any new structures, fill, building additions, fencing (including landscaping or plantings designed to act as a fence), and storage of materials is not permitted in the linear water body except as specifically permitted for the following uses:
               a.   Public flood control structures and private improvements relating to the control of drainage and flooding of existing buildings, erosion, water quality, or habitat for fish and wildlife;
               b.   Structures or facilities relating to functionally water dependent uses such as facilities and improvements relating to recreational boating, and as modifications or additions to existing wastewater treatment facilities;
               c.   Storm and sanitary sewer outfalls;
               d.   Underground and overhead utilities if sufficiently flood-proofed;
               e.   Bridges, culverts, and associated roadways, sidewalks, and railways, necessary for crossing over the linear water body; and
               f.   Linear water body regrading, without fill, to create a positive non-erosive slope toward a linear water body.
         (c)   Linear water body modification:
            1.   All development or modification of a linear water body with a tributary drainage area of 640 acres or more is subject to compliance with the standards for regulatory floodway development contained in § 151.147. All development or modification of a linear water body with a tributary drainage area of 100 acres or more is subject to compliance with the standards for flood-prone area development contained in § 151.147.
            2.   All linear water body modification is subject to compliance with the following standards.
               a.   Stormwater velocities at the discharge point of a modified linear water body shall not exceed those of the existing linear water body at the same point.
               b.   If a stream or linear water body meeting the definition of waters of the United States or isolated waters of Lake County is modified, a stream or linear water body mitigation plan shall be submitted for review and approval to the Planning, Building and Development Director. The plan shall show how the physical characteristics of the modified linear water body shall, at a minimum, meet the existing linear water body in length, cross-section, slope, sinuosity, and carrying capacity of the original linear water body. The plan shall also reestablish vegetation within the stream and overbanks using the Native Plant Guide for Streams and Stormwater Facilities in Northeastern Illinois, NRCS, et al. (as amended), as a minimum standard for the re-vegetation plan.
               c.   All disturbed areas associated with a linear water body modification, including the buffer or setback area, shall be seeded or otherwise stabilized in accordance with subsection (J) below.
               d.   Prior to the commence-ment of linear water body modification, an approved and effective means to reduce sedimentation and degradation of downstream water quality shall be installed. The measures and practices utilized to reduce sedimentation and degradation of downstream water quality shall be maintained throughout the construction period.
               e.   New or relocated linear water bodies shall be built in the dry. All items of construction, including vegetation, shall be completed prior to diversion of water into the new linear water body.
               f.   New or relocated linear water bodies with a tributary drainage area of 20 acres or more shall be built no closer than 30 feet to the ultimate rights-of-way of any public collectors, arterials, or freeways; buildings; structures or other impervious surface areas (e.g., driveways and parking areas) except when the Planning, Building and Development Director finds that existing conditions, such as the exceptional narrowness of a platted lot, will prohibit the reasonable use of a property if the 30-foot setback is imposed. The buffer requirements of subsection (H)(5) above shall also be met. In no event shall relocated water bodies be located closer than ten feet to the ultimate right-of-way of public roads.
               g.   Linear water bodies shall be expected to withstand all flood events up to the base flood without increased erosion. The use of armoring of banks using bulkheads, rip-rap and other materials shall be avoided. Armoring shall only be used where erosion cannot be prevented in any other way such as use of vegetation or gradual slopes. The armoring shall have minimal impact on other properties, linear water bodies, and the existing land configuration.
               h.   All new or relocated linear water bodies shall be located within a drainage easement. For new or relocated linear water bodies draining 20 or more acres, the drainage easement shall extend at least 12 feet from top of bank along at least one side of the linear water body. All drainage easements shall be accessible to vehicular equipment. No drainage easement shall be on or within the ultimate right-of-way of any public road.
               i.   Construction vehicles shall cross linear water bodies by means of existing bridges or culverts. Where an existing crossing is not available, a temporary crossing shall be constructed that complies with all of the following standards:
                  (i)   The approach roads will be six inches or less above natural grade;
                  (ii)   The crossing will allow linear water body flow to pass without backing up the water above the stream bank vegetation line or above any drainage tile or outfall;
                  (iii)   The top of the roadway fill in the linear water body will be at least two feet below the top of the lowest bank. Any fill in the linear water body shall be non-erosive material, such as rip-rap or gravel;
                  (iv)   All disturbed linear water body banks will be seeded or otherwise stabilized as soon as possible, in accordance with subsection (J), upon installation and again upon removal of construction; and
                  (v)   The access road and temporary crossings will be removed within one year after installation, unless an extension of time is granted by the Planning, Building and Development Director.
         (d)   1.   All proposed public road rights-of-way, buildings, structures, driveways, and parking areas shall be set back at least 30 feet from the ordinary high water mark with a tributary drainage area of 20 acres or more except for the following:
               a.   Fences that are a maximum of four feet in height and that are at least 50% open (e.g., chain link, split rail, picket, and the like) in subdivisions approved prior to October 12, 1992, are exempt from setback requirements. (Note: fences may begin at the shoreline.);
               b.   The setback for decks shall not be less than 20 feet in subdivisions approved prior to October 12, 1992; and
               c.   The Planning, Building and Development Director shall be authorized to reduce these required setbacks when it is determined that existing conditions, such as the exceptional narrowness of a platted lot, will prohibit the reasonable use of the property if the setback is imposed. The determinations shall be reported to the Planning, Building and Zoning Committee in accordance with the provisions of § 151.032(A)(16).
            2.   The buffer requirements of subsection (H)(5) above shall also be met for all subdivisions approved after August 1999.
         (e)   Public health protection standards:
            1.   No development in a linear water body shall include locating or storing chemicals, explosives, buoyant materials, animal wastes, fertilizers, flammable liquids, pollutants, or other hazardous or toxic materials below the flood protection elevation.
            2.   New and replacement water supply systems, wells, and sanitary sewer lines may be permitted, providing all manholes or other above-ground openings located below the flood protection elevation are watertight.
            3.   On-site individual sewage disposal systems shall be designed to avoid inundation by the base flood.
   (I)   Maintenance of stormwater management systems.  All improvements required by this section shall be maintained in perpetuity and cannot be developed for any other use which would limit or cause to limit the intended function and/or use of the improvements. To ensure continued maintenance of all stormwater management systems all development shall comply with the following standards.
      (1)   For new developments not involving a plat of subdivision or plat of condominium, but for which the provisions of this section are applicable, maintenance responsibilities assigned by this section shall be those of the property owner. In these cases, a covenant approved by the Planning, Building and Development Director providing for perpetual maintenance of required facilities shall be recorded with the Lake County Recorder prior to issuance of any certificate of occupancy for the development.
      (2)   For new developments that involve a plat of subdivision or plat of condominium, a property owners’ association or condominium association shall be formed in perpetuity for the maintenance of the improvements required by this section. Membership in the association shall be mandatory for all owners. Articles of agreement of and providing for the association must be approved by the Planning, Building and Development Director before recording of a plat. Furthermore, the association shall be chartered by this state prior to the release of any final maintenance guarantee held by the county for the relevant development.
      (3)   Improvements required by this section shall be maintained by the association of the development and each owner shall bear his or her proportionate responsibility for continued maintenance. A special note shall appear on any final plat of subdivision or any plat of condominium and their declarations.
      (4)   However, the developer shall be responsible for the maintenance of all improvements until the time that 80% of the lots or units in the development have been sold. The developer shall not transfer these improvements for the purpose of maintenance until all maintenance assurances held for required improvements have been released by the county.
      (5)   In new residential developments consisting of five or fewer dwelling units, the provision of an association may be waived, provided that other parts of this section have been met, and that covenants providing for shared maintenance responsibilities have been approved by the Planning, Building and Development Director and recorded with the Lake County Recorder.
   (J)   Soil erosion and sediment control.  Soil erosion and sediment control related measures are required to be constructed and maintained for any regulated land disturbance activity, in accordance with the standards of this section. All temporary measures and permanent erosion and sediment control shall be maintained continuously in an effective, working condition.
      (1)   Soil disturbance shall be conducted in such a manner as to minimize erosion. Areas of the development site that are not to be graded shall be protected from construction traffic or other disturbance until final seeding is performed. Soil stabilization shall consider the time of year, site conditions, and the use of temporary or permanent measures.
      (2)   Properties and linear and nonlinear water bodies adjoining development sites shall be protected from erosion and sedimentation. At points where concentrated flow leaves a development site, energy dissipation devices shall be placed at discharge locations and along the length of any outfall channel as necessary to provide a non-erosive velocity of flow from the structure to the watercourse so that the natural physical and biological characteristics and functions are maintained and protected.
      (3)   Sediment control measures shall be constructed prior to the commencement of  hydrologic disturbance of upland areas.
      (4)   Disturbed areas shall be stabilized with temporary or permanent measures within seven calendar days following the end of active hydrologic disturbance, or redisturbance, consistent with the following criteria or using an appropriate measure as approved by the Planning, Building and Development Director:
         (a)   Appropriate temporary or permanent stabilization measures shall include seeding, mulching, sodding, and/or non-vegetative measures.
         (b)   Disturbance to areas or embankments having slopes equal to or steeper than 3H:1V shall be minimized; disturbed slopes shall be stabilized with staked-in-place sod, appropriately specified mat, or blanket, or other appropriate measure(s) in combination with seeding.
         (c)   Erosion control blanket shall be required on all interior detention basin side slopes between normal water level and high water level. The seven calendar day stabilization requirement may be precluded by snow cover or where land disturbing activities will resume within 14 calendar days from when the active hydrologic disturbance ceased, provided that the disturbed portion of the development site has appropriate erosion and sediment controls.
      (5)   Land disturbance activities in streams shall be avoided, where possible. If disturbance activities are unavoidable, the following requirements shall be met:
         (a)   Where stream construction crossings are necessary, temporary crossings shall be constructed of non-erosive material; and
         (b)   The time and area of disturbance of a stream shall be kept to a minimum. The stream, including bed and banks, shall be restabilized within 48 hours after channel disturbance is completed or interrupted.
      (6)   Soil erosion and sediment control measures shall be appropriate with regard to the amount of tributary area to the measure as follows.
         (a)   Disturbed areas draining greater than 1,000 square feet but less than one acre shall, at
a minimum, be protected by a filter barrier (including filter fences, which at a minimum, meet the applicable sections of the AASHTO Standard Specification to 288-00, or equivalent control measures) to control all off-site runoff. Vegetated filter strips, with a minimum width of 25 feet, in the direction of flow, may be used as an alternative only where runoff in sheet flow is expected.
         (b)   Disturbed areas draining more than one but fewer than five acres shall, at a minimum, be protected by a sediment trap or equivalent control measure at a point downslope of the disturbed area.
         (c)   Disturbed areas draining more than five acres, shall, at a minimum, be protected by a sediment basin with a perforated filtered riser pipe or equivalent control measure at a point downslope of the disturbed area.
         (d)   Sediment basins shall have both a permanent pool (dead storage) and additional volume (active storage) with each volume equal to the runoff amount of a two-year, 24-hour event over the on-site hydrologically disturbed tributary area to the sediment basin. Two-year storm runoff volumes vs. site runoff curve numbers are shown in Appendix J. The available sediment volume below normal water level, in addition to the dead storage, shall be sized to store the estimated sediment load generated from the site over the duration of the construction period. For construction periods exceeding one year, the one-year sediment load and a sediment removal schedule may be substituted. If the detention basin for the proposed developed condition of the site is used for sediment basin, the above volume requirements will be explicitly met. Until the site is finally stabilized, the basin permanent pool of water shall meet the above volume requirements and have a filtered perforated riser protecting the outflow pipe.
      (7)   All storm sewers that are or will be functioning during construction shall be protected by an appropriate sediment control measure.
      (8)   If dewatering services are used, adjoining properties and discharge locations shall be protected from erosion and sedimentation. Discharges shall be routed through an approved anionic polymer dewatering system or similar measure as approved by the Planning, Building and Development Director. The Planning, Building and Development Director, or approved representative, must be present at the commencement of dewatering activities.
      (9)   All temporary erosion and sediment control measures shall be removed within 30 days after final site stabilization is achieved or after the temporary measures are no longer needed. Trapped sediment and other disturbed soil areas shall be permanently stabilized.
      (10)   A stabilized mat of crushed stone meeting Illinois Department of Transportation gradation CA-1 underlain with filter fabric and in accordance with the Illinois Urban Manual, or other measure(s) as approved by the Planning, Building and Development Director shall be located at any point where traffic will be entering or leaving a development site to or from a public right-of-way, street, alley, or parking area. Pollutants from equipment and vehicle washing, wheel wash water, and other wash waters shall be treated in a sediment basin or other appropriate measure(s) designed to minimize the discharge of pollutants, as approved by the Planning, Building and Development Director. Any sediment or soil reaching an improved public right-of-way, street, alley, or parking area shall be removed by scraping or street cleaning as accumulations warrant and transported to a controlled sediment disposal area. The Planning, Building and Development Director may require additional stabilized construction entrance methods.
      (11)   The applicant shall minimize the discharge of pollutants from the exposure of building materials, building products, landscape materials (e.g. fertilizers, pesticides, herbicides), detergents, sanitary waste, and other on-site materials to precipitation and stormwater runoff.
      (12)   If the installed soil erosion and sediment controls do not minimize sediment leaving the development site, additional measures such as anionic polymers or filtration systems may be required by the Planning, Building and Development Director.
      (13)   If stripping, clearing, grading, or landscaping are to be done in phases, the permitee shall plan for appropriate erosion control measures to be in place after each stage listed in § 151.145(E)(7).
      (14)   Earthen embankments shall be constructed with side slopes no steeper than 3H:1V. Steeper slopes may be constructed with appropriate stabilization as approved by the Planning, Building and Development Director.
      (15)   Stormwater conveyance channels, including ditches, swales, and diversions, and the outlets of all channels and pipes shall be designed and constructed to withstand the expected flow velocity from the ten-year frequency storm without erosion. All constructed or modified channels shall be stabilized within 48 hours.
      (16)   Temporary diversions shall be constructed as necessary to direct all runoff from hydrologically disturbed areas to the appropriate sediment trap or basin.
      (17)   Soil stockpiles shall not be located in a flood-prone area or designated buffer protecting waters of the United States or isolated waters of Lake County. Soil stockpiles are defined as having greater than 100 cubic yards of soil and will remain in place for more than seven days. Soil stockpile locations shall be shown on the soil erosion and sediment control plan and shall have the appropriate measures to prevent erosion of the stockpile.
      (18)   Standards and specifications contained in the Illinois Urban Manual, as amended, and the planning and procedures sections of the Illinois Procedures and Standards for Urban Soil Erosion and Sedimentation Control, as amended, provide guidance for presenting soil erosion and sediment control plan specifications and delineating procedures and methods of operation under site development for sediment and erosion control. In the event of conflict between provisions of the manuals and of this chapter, this chapter shall govern.
      (19)   The applicant shall provide adequate receptacles for the deposition of all construction material debris generated during the development process. The applicant shall not cause or permit the dumping, depositing, dropping, throwing, discarding or leaving of construction material debris upon or into any development site, channel, waters of the United States, or isolated waters of Lake County. The applicant shall maintain the development site free of construction material debris.
      (20)   Designated Erosion Control Program standards and Inspector requirements.
         (a)   Standards.
            1.   A Designated Erosion Control Inspector, hired or employed by the applicant, shall be required for development in (a) and (b), and may be required by the Planning, Building and Development Director for (c):
               a.   Exceeds ten acres of hydrologic disturbance; or
               b.   Exceeds one acre of hydrologic disturbance and has a regulatory floodplain, isolated waters of Lake County or waters of the United States on-site or on a downstream adjoining property; or
               c.   Is less than or equal to one acre of hydrologic disturbance and has a regulatory floodplain, isolated waters of Lake County, or waters of the United States on-site or on a downstream adjoining property.
            2.   Subsection (J)(20)(b) and § 151.145(E)(7) contains inspection requirements for development meeting the above thresholds for program inclusion and Designated Erosion Control Inspector requirements.
            3.   Subsection (J)(17)(b) below contains inspection requirements for development meeting the above threshold for program inclusion and Designated Erosion Control Inspector requirements.
            4.   The applicant shall submit the name of the Designated Erosion Control Inspector to the Planning, Building and Development Director before issuance of site development permit.
         (b)   Designated Erosion Control Inspector requirements. The Designated Erosion Control Inspector shall inspect the development site as specified below and, at a minimum, perform the following:
            1.   Keep a copy of the Planning, Building and Development Director-approved soil erosion and sediment control plans at the development site at all times;
            2.   Keep a written log of all inspections that shall contain, at a minimum, conditions of the soil erosion and sediment control measures and any corrective actions that need to be taken. The Designated Erosion Control Inspector log shall be kept at the development site at all times and shall be made available for inspection upon request of the Planning, Building and Development Director;
            3.   Notify the Planning, Building and Development Director within 24 hours when the development site is determined to be not in compliance with this chapter or the approved soil erosion and sediment control plans and the proposed corrective measures to be taken; and
            4.   Recommend to the applicant additional soil erosion and sediment control prevention measures, if necessary, to reduce sediment leaving a development.
   (K)   Landscape features.  All landscape features including, berms, planters, walls, fences and the like shall be placed or constructed in such a manner as not to interfere with the natural drainage pattern, so as not to obstruct a clear view at street intersections (see § 151.172), and so that the features do not cause a drainage nuisance. In addition, the placement and construction of all landscape berms shall conform to all of the following standards:
      (1)   The slope of any berm embankment shall not exceed, at its steepest point, a slope of 3:1;
      (2)   The height of any berm embankment, measured from the toe to the top, shall not exceed 20 feet;
 
COMMENTARY:
For purposes of measuring the height of a berm in instances involving grade changes on both sides of a berm, the berm height shall be measured on the side of the berm whose toe is located at a higher elevation.
 
      (3)   The toe of any berm embankment shall be no closer than ten feet from any property line or ultimate right-of-way line;
      (4)   The top of all berms shall be graded to be smoothly convex and the toe of all berms shall be graded to be smoothly concave;
      (5)   All erosive surfaces on any berm shall be permanently stabilized in accordance with subsection (J) above;
      (6)   In addition to meeting the erosion control standards contained in subsection (J) above, all berms not required in a perimeter landscape transition area shall comply with the berm landscaping requirements of § 151.167(E)(2)(f); and
      (7)   A conceptual land use plan shall be submitted in conjunction with an application for any berm in excess of ten feet in height.
   (L)   Temporary soil stockpiles.
      (1)   Temporary soil stockpiles shall be placed no closer than ten feet from any property line, road right-of-way and no closer than 30 feet from natural resource protection areas (e.g., buffers, woodlands). Temporary soil stockpiles shall not be located within the regulatory floodplain, regulatory floodway, flood-prone area, linear water body, overland flow path, or any other natural resource protection area.
      (2)   The location and size of a temporary soil stockpile shall not interfere with the natural drainage pattern or obstruct a clear view at street intersections (see § 151.172).
      (3)   Temporary soil stockpiles shall be removed completely and the soil surface permanently stabilized within two years of establishment, except when otherwise approved by the Planning, Building and Development Director.
      (4)   Adequate measures and practices shall be utilized to control erosion of the stockpile (see subsection (J) above).
      (5)   Temporary soil stockpiles shall not exceed a maximum height of 20 feet.
   (M)   Wetlands.
      (1)   Applicability. The standards of this subsection (M) apply when waters of the Unites States or isolated waters of Lake County are located wholly or partially within the development site.
      (2)   Wetland submittal requirements.  In addition to all other Watershed Development Ordinance provisions of this chapter, wetland permit submittal requirements depend upon whether the development site contains waters of the United States or isolated waters of Lake County as provided below.
         (a)   The applicant shall provide a valid written jurisdictional determination from the U.S. Army Corps of Engineers or a Corps-approved agency as to which wetlands on the development site are isolated waters of Lake County or waters of the United States.  A copy of the jurisdictional determination shall be included with the wetland submittal.
         (b)   For development containing waters of the United States or isolated waters of Lake County, but with no proposed impacts, the following information is required for a Letter of No Impact (LONI):
            1.   A cover letter describing the proposed activity:
            2.   Development plan(s) as specified in § 151.145(F);
            3.   A wetland hydrology analysis meeting the requirements of subsection (M)(7) when there is a modification of tributary drainage area or surface runoff volume to isolated waters of Lake County;
            4.   A letter from the U.S. Army Corps stating that the proposed development will not impact waters of the United States, if required by the Lake County Stormwater Management Commission or the isolated wetland certified community.
         (c)   For wetland impacts to waters of the United States, the following information is required:
            1.   Wetland delineation and wetland determination report as specified in subsection (M)(3) of this section;
            2.   A U.S. Army Corps permit for the proposed development or a letter from the Corps stating that the proposed development does not require Corps authorization;
            3.   Buffer area requirements as specified in subsection (H)(5) of this section; and
            4.   All wetland impacts occurring in county that exceed the mitigation threshold of the Corps regulatory program shall be mitigated for in county at the mitigation ratio specified by the Corps for that development impact.
         (d)   For wetland impacts to isolated waters of Lake County, the following information is required:
            1.   A cover letter signed by a certified wetland specialist, that provides a clear project purpose and need statement, a description of the proposed activity, area (in acres) of wetland impact and a statement on the category to be used as follows:
               a.   Category I: Wetland impacts less than or equal to one acre and does not impact high-quality aquatic resources;
               b.   Category II: Wetland impacts greater than one acre and less than two acres and does not impact high-quality aquatic resources;
               c.    Category III: Wetland impacts greater than or equal to two acres or impacts high-quality aquatic resources; and
               d.   Category IV: Wetland impacts for the restoration, creation, and enhancement of wetlands, provided that there are net gains in aquatic resource function. Category IV activities include shoreline and streambank erosion restoration described in § 151.149(E)(3).
            2.   A completed watershed development permit application form signed by a certified wetland specialist;
            3.   A delineation of the wetlands consistent with the requirements provided in subsection (M)(3) of this chapter;
            4.   Development site plan(s) meeting the requirements of § 151.145(F) showing the boundaries of all existing wetlands or water bodies on the ownership parcel, including the development site and the areas of proposed wetland impacts.
            5.   A statement on the occurrence of any high-quality aquatic resource on or adjoining the development;
            6.   For developments involving state funding or pass-through funding, documentation that the development is in compliance with the intra-agency Wetland Policy Act of 1989 [20 ILCS 830] as administered by the Illinois Department of Natural Resources;
            7.   Documentation that the development is in compliance with the U.S. Fish and Wildlife Service’s consultation program under the Endangered Species Act;
            8.   A mitigation plan meeting the requirements of subsection (M)(4);
            9.   A copy of the natural resources information report (NRI) for development that is required to obtain a NRI performed by the McHenry-Lake County Soil and Water Conservation District pursuant to state statute 70 ILCS 405/22.02a;
            10.   A narrative of the alternative measures taken to avoid, minimize, or mitigate for wetland impacts to isolated waters of Lake County (Category II requirement only);
            11.   Category III wetland impacts:
               a.   A narrative of the measures taken, in sequence, to avoid and minimize wetland impacts to isolated waters of Lake County before mitigation is considered;
               b.   Upon concurrence of the Planning, Building and Development Director, and the Lake County Stormwater Management Commission or the Isolated Waters of Lake County-Certified Community’s Certified Wetland Specialist that a site development permit application meets all other wetland submittal requirements of this chapter, the Lake County Stormwater Management Commission or the Isolated Waters of Lake County-Certified Community’s Certified Wetland Specialist shall issue a technical notification to the U.S. Army Corps of Engineers, Illinois Department of Natural Resources, Illinois Environmental Protection Agency, U.S. Fish and Wildlife Service, and the Lake County Stormwater Management Commission requesting comments with respect to the proposed wetland impacts within 15 working days. The Lake County Stormwater Management Commission or the Isolated Waters of Lake County-Certified Community’s Certified Wetland Specialist shall receive the comments and copies of the comments shall be forwarded to the applicant for response. Full consideration of the comments and applicant’s response shall be evaluated by the Lake County Stormwater Management Commission or the Isolated Waters of Lake County-Certified Community’s Certified Wetland Specialist for compliance with § 151.145(A)(10) prior to approval of wetland provisions and permit issuance; and
               c.   The Lake County Stormwater Management Commission shall review and issue Category III wetland authorizations for development sites occurring in more than one local unit of government jurisdiction.
            12.   Category IV wetland impacts:
               a.   A narrative on the benefits to the aquatic environment of the proposed development.
               b.   Shoreline and streambank erosion restoration that meet the requirements contained in § 151.149(E)(3) are exempt from submittal requirements contained in this section.
               c.    isolated waters of Lake County that are used for detention and not for mitigation credit per subsection (M)(6) shall be exempt from the submittal requirements of subsection (M)(2)(d)8. above.
      (3)   Requirements for wetland delineation.
         (a)   The applicant shall identify the boundaries, extent, function, and quality of all wetland areas on the development site and prepare a wetland determination report. The presence and extent of wetland areas shall be determined by, or under the supervision of, a certified wetland specialist using an on-site wetland procedure within three years of the initial permit application date in accordance with the methodology contained in the 1987 Corps of Engineers Wetland Delineation Manual (as amended, including applicable supplements) or as otherwise noted below.
         (b)   Wetland determination report.  The following are minimum requirements for the wetland determination report:
            1.   A plan showing the location of wetlands within the development site and the approximate boundaries of offsite wetlands per subsection (M)(3)(b)6 below. The wetland boundary within the development site shall be flagged in the field and surveyed;
            2.   An aerial photograph delineating the wetland and the development boundary;
            3.   A copy of the following maps (most recent) delineating the development boundary;
               a.   U.S. Geological Survey quadrangle map;
               b.   Lake County wetland inventory map;
               c.   Federal Emergency Management Agency floodplain map;
               d.   Lake County soil survey; and
               e.   Hydrologic atlas.
            4.   U.S. Army Corps of Engineers data sheets (March 1992 or most recent version) with color photographs provided for representative upland and wetland data point;
            5.   A written description of the wetland(s) that includes a floristic quality assessment as determined by methodology contained in Swink, F. and G. Wilhelm’s Plants of the Chicago Region (1994, 4th Edition, The Morton Arboretum, Lisle, Illinois). Floristic quality assessments shall generally be conducted between May 15 and October 1 which approximates the growing season. Non-growing season assessments may require additional sampling during the growing season to satisfy this requirement;
            6.   The approximate location, extent, and relative quality of off-site wetlands on properties within the maximum buffer requirements adjoining the development shall be identified by using the first of the following documents or procedures pertaining at the time of development:
               a.   Site-specific delineation according to the 1987 federal wetland delineation manual. If this delineation is not available, use subsection (M)(3)(b)6.b. below; or
               b.   Wetlands identified in county wetland inventory maps (most current Lake County Wetland Inventory map).
            7.   A farmed wetland determination for development sites in accordance with the current U.S. Natural Resources Conservation Service methodology. The farmed wetland boundaries shall be shown on the plan and aerial photograph in subsections (M)(3)(b)1. and (M)(3)(b)2. above. A report for the development site indicating the presence of cropland wetlands as defined by the National Food Security Act Manual (most recent edition).
      (4)   Isolated Waters of Lake County mitigation requirements.
         (a)   Mitigation is required within the county for:
            1.   Wetland impacts greater than one-tenth acre of isolated waters of Lake County including those that are high-quality aquatic resources.
            2.   For single-lot, single-family residences provided the activity is a single and complete project: wetland impacts greater than 0.25 acre of isolated waters of Lake County or 0.10 acre of isolated waters of Lake County that are high-quality aquatic resources.
         (b)   Mitigation shall provide for the replacement of the wetland environment lost to development at the following proportional rates (i.e., creation acreage to wetland impact acreage):
            1.   For wetland impacts to areas that are not high quality aquatic resources under Categories I, II, and III, a minimum of 1.5:1 mitigation ratio shall be required or a minimum 1:1 mitigation ratio for fully certified wetland mitigation bank credits;
            2.   A minimum of 3:1 for wetland impacts that are high-quality aquatic resources;
            3.   A minimum of 6:1 for wetland impacts that are high-quality forested wetlands as defined in Appendix N;  and
            4.   For wetland impacts to open waters that are not high-quality aquatic resources under Categories I, II, and III, a minimum of 1:1 mitigation ratio shall be required.
         (c)   Mitigated isolated waters of Lake County shall be designed to duplicate or improve the hydrologic and biologic features of the original wetland impact area.
         (d)   A project mitigation document (PMD) shall be submitted for all mitigation projects in conformance with Appendix S. Appendix S contains requirements for performance standards, monitoring, and completion standards.
         (e)   Creation of wetlands for the mitigation of wetland impacts shall not take place within detention facilities. Enhancement of farmed wetlands meeting the size criterion in subsection (M)(5)(a) may be used for up to 80% of the mitigation requirement.
         (f)   Enhancement of existing non-farmed wetlands may be credited at up to 25% of the enhanced wetland acreage completed, provided that the wetland impact acreage created is at a minimum 1:1 ratio and the mitigation hierarchy in §§ 151.145 through 151.154 is followed.
         (g)   A five-year wetland mitigation surety for 110% of mitigation cost shall be submitted prior to obtaining a permit. The mitigation surety shall include the costs for construction, monitoring, and management activities during the five-year performance period.
         (h)   A wetland mitigation management and monitoring plan indicating the legally responsible parties for long-term operation and maintenance and dedicated funding sources.
         (i)   The developer shall provide annual monitoring reports on the status of the constructed mitigation measures. The developer shall undertake all necessary remedial action to bring the area into compliance with the wetland mitigation plan.
         (j)   Wetland impacts occurring prior to issuance of a Watershed Development Ordinance permit shall presume the wetland disturbed was a high-quality aquatic resource requiring mitigation at a minimum rate of 3:1, except 6:1 for wetland impacts that are forested wetlands as defined in Appendix N.
         (k)   Mitigation areas shall have the same buffer area requirements and mitigation credit for established buffer areas as described in Appendix S for Lake County Stormwater Management Commission-approved wetland mitigation banks.
         (l)   Mitigation areas shall be protected by a deed or plat restriction for that purpose.
      (5)   Mitigation hierarchy.
         (a)   Size requirements.  If the required mitigation acreage is less than one and one-half acres, mitigation requirements shall follow the mitigation hierarchy (b)1. through 4. below. If on-site mitigation increases an existing on-site wetland size to greater than or equal to one and one-half acres, the applicant may use mitigation hierarchy (b)1. If the required mitigation acreage is one and one-half acres or greater, mitigation requirements shall follow mitigation hierarchy (b)1. through 4.
         (b)   Hierarchy.  All mitigation shall occur in the county. Mitigation shall use the following hierarchy. Allowance to the next lower step is permitted only when justified through sequencing specified in subsections (M)(2)(d)10. and (M)(2)(d)11. or when the higher step is not available or as specified in subsection (M)(5)(b)4. below:
            1.   On-site wetland mitigation meeting the requirements of the project mitigation document;
            2.   In the same watershed as wetland impact: a U.S. Army Corps approved wetland mitigation bank; or a Lake County Stormwater Management Commission approved wetland mitigation bank; or off-site wetland mitigation meeting the requirements of the project mitigation document;
            3.   Outside of the watershed (at double the required mitigation acreage): a U.S. Army Corps approved wetland mitigation bank; or a Lake County Stormwater Management Commission approved wetland mitigation bank; or off-site wetland mitigation meeting the requirements of the project mitigation document; or
            4.   Lake County Stormwater Management Commission Wetland Restoration Fund. This mitigation option may only be used for wetland impacts where there are no available mitigation credits within the watershed and the corresponding fees and mitigation ratios shall be charged at the in-watershed rate.
      (6)   Detention in isolated waters of Lake County.
         (a)   Detention shall only be allowed in the following isolated waters of Lake County and may not be considered a wetland impact, subject to provisions of subsections (M)(6)(b) and (M)(6)(c):
            1.   Farmed wetlands;
            2.   Non-farmed wetlands that are not high quality aquatic resources when the existing vegetated wetland acreage (not including open water area) is either:
               a.   Covered by a minimum of 85% of one or more of the following species:
                  i.   Reed canary grass (Phalaris arundinacea);
                  ii.   Purple loosestrife (Lythrum salicaria);
                  iii.   Common reed (Phragmites australis); or
                  iv.   Buckthorn (Rhamnus spp.).
               b.   Has an FQI of seven or less.
            3.   An isolated waters of Lake County comprised of open water that is not a high quality aquatic resources;
            4.   Non-farmed wetlands not meeting subsection (M)(6)(a)2. that are not high quality aquatic resources and wholly located within a deed or plat restriction may be utilized for detention greater than the required two-year, 24-hour volume. The outlet design shall maintain or replicate the existing hydrologic condition of the wetland, unless changes are proposed to enhance the wetland function. Excavation or grading shall be considered an impact under the appropriate impact Category I, II, or III.
         (b)   The following shall apply when using isolated waters of Lake County for detention and not for wetland enhancement mitigation credit:
            1.   The applicant shall use a “wetland detention basin” design as provided in the Technical Reference Manual (TRM), and shall reestablish vegetation within the detention basin using the Native Plant Guide for Streams and Stormwater Facilities in Northeastern Illinois, NRCS, et al. (as amended) as a minimum standard for the re-vegetation plan.
            2.   Reduction of wetland area within the existing delineated wetland boundary from existing to proposed conditions shall be reviewed as an impact under the appropriate impact Category I, II, or III.
            3.   Excavation of existing wetland as part of the proposed wetland detention basin design shall be reviewed under Category IV meeting the criteria of subsections (M)(6)(a)1., (M)(6)(a)2., and (M)(6)(a)3.
            4.   The wetland hydrology thresholds of subsection (M)(7) shall apply for isolated waters of Lake County meeting the criteria of subsections (M)(6)(a)1. and (M)(6)(a)4.
            5.   The requirements for water quality treatment of subsection (H)(4) shall apply upstream of the isolated waters of Lake County.
            6.   The maintainable outlet requirements of subsection (C)(2) shall apply.
         (c)   The following shall apply when using isolated waters of Lake County for detention and for wetland enhancement mitigation credit:
            1.   Isolated waters of Lake County meeting the criteria of subsection (M)(6)(a) may be used for wetland enhancement mitigation credit.
            2.   Wetland enhancement within the proposed detention basin shall be reviewed under Category IV requirements, and the performance standards listed in Appendix S, Section H, shall apply.
            3.   Reduction of wetland area within the existing delineated wetland boundary from existing to proposed conditions shall be reviewed as an impact under the appropriate impact Category I, II, or III.
            4.   The mitigation requirements of subsection (M)(4) shall apply.
            5.   The wetland hydrology thresholds of subsection (M)(7) shall apply.
            6.   The requirements for water quality treatment of subsection (H)(4) shall apply upstream of the isolated waters of Lake County.
      (7)   Wetland hydrology requirement. The following hydrology requirement applies to isolated waters of Lake County located wholly or partially within the ownership parcel, including the development site. The runoff volume reduction requirements (subsection (D)(2)) may be modified to satisfy the wetland hydrology requirement for the portion of the development site tributary to the wetland.
         (a)   The development design shall maintain between 80% and 150% of the existing condition, two-year, 24-hour storm event runoff volumes from the on-site tributary drainage area to the preserved isolated water of Lake County. The following minimum information shall be submitted to address this provision:
            1.   An exhibit illustrating the existing condition and with-project drainage areas;
            2.   Existing condition and with-project runoff volume calculations (including land use and soil type documentation);
            3.   Existing condition and with-project runoff volume determination. For proposed development that will change the size of an isolated waters of Lake County, the proposed to existing conditions runoff volume ratio shall be adjusted according to the change in wetland size, to determine if the hydrology threshold has been met; and
            4.   The development shall include a design for the stormwater management system that maintains or replicates the existing hydrologic condition of the wetland, unless changes are proposed to enhance the wetland function.
         (b)   A wetland impact to isolated waters of Lake County shall be assumed and the mitigation requirements of subsection (M)(4) shall apply if the development does not meet provisions of subsection (M)(7)(a) above. The hydrologic wetland impact shall be in addition to other wetland impacts to isolated waters of Lake County (e.g., filling, excavation, drainage, and the like). The amount of wetland impact shall be determined as follows:
            1.   For isolated waters of Lake County wholly on-site: the total area of the impacted isolated waters of Lake County not meeting the above provisions; and
            2.   For isolated waters of Lake County located partially on-site: the ratio of on-site tributary drainage area to total tributary drainage area multiplied by the with project area of the impacted isolated waters of Lake County.
      (8)   Resource protected area.  Wetlands shall be protected and set aside as open space in accordance with § 151.072.
      (9)   Wetland development or disturbance.  Development or disturbance of wetlands shall be allowed only if reviewed and approved in accordance with the wetland development standards of division (M) above and with the following standards:
         (a)   A permit approving the proposed wetland development shall be received from the U.S. Army Corps of Engineers;
         (b)   The establishment of any permitted use, construction of any permitted structure, excavation or filling of any wetland may be permitted only if:
            1.   The parcel, use, and/or structure would conform to all other standards of this chapter if the wetland were not present; and
            2.   The location, amount, or configuration of a site’s buildable area precludes the construction of any permitted principal structure or establishment of any reasonable permitted use of land.
         (c)   In addition to the above standards, all applications for the development of exceptional functional value wetlands shall demonstrate that the proposed use is so location dependent that it can not practically be established outside of the wetland.
(Ord., § 8.2, passed 10-13-2009; Ord. passed 10-9-2012)