Loading...
(A) The drainage system should be designed to minimize adverse surface and groundwater quality impacts off-site and on the property itself. Detention basins shall incorporate design features to capture storm water runoff pollutants. When designers propose wet bottom and wetland type designs, all flows from the development shall be routed through the basin (i.e. low flows shall not be bypassed). When it is not practical or feasible to route all of the project’s flow to the detention basin, the design of the basin shall compensate for the bypass flow. In cases where detention facilities are practical and the long term maintenance of such facilities are provided for, detention of storm water shall be promoted through the property’s drainage system to reduce the volume of storm water runoff and to reduce the quantity of runoff pollutants.
(B) The drainage system should incorporate multiple uses where practicable. Uses considered compatible with storm water management include open space, aesthetics, aquatic habitat, recreation (boating, fishing, trails, playing fields), wetlands and water quality mitigation.
(C) Water quality shall adhere to:
(1) Illinois Environmental Protection Act: 415 ILCS 5/11 and 5/12, from Ch. 111-1/2, par 1011 and 1012;
(2) Illinois Pollution Control Board Rules and Regulation: Title 35: Environmental Protection, Subtitle C: Water Pollution, Chapter I: Pollution Control Board, Part 302 Water Quality Standards; and
(3) Illinois Pollution Control Board Rules and Regulations: Title 35: Environmental Protection, Subtitle C: Water Pollution, Chapter I: Pollution Control Board, Part 304 Effluent Standard.
(Ord. passed 9-8-2009)
(A) (1) Release rates. The drainage system for new developments or redevelopments shall be designed to control the peak rate of discharge from the property for the two-year, 24-hour and 100-year, 24-hour events to discharge rates at or below those which existed prior to development. Additionally, the discharge from a storm water detention facility shall not cause an increase in flooding or channel instability downstream when considered in aggregate with other developed properties and downstream drainage capacities.
(2) Detention basin outlet design. The detention basin outlet control structure shall be designed to account for observed or anticipated downstream tailwater elevations. The tailwater elevations used in the detention model shall be for the particular storm frequency being routed through the detention basin. An emergency spillway or overflow device shall be provided and set at an elevation equivalent to the 100-year design high water. A calculation shall be made to determine the water elevation in the detention basin that would result from a 100-year storm with the outflow control structure openings blocked. The discharge rate flowing through the emergency spillway shall not exceed the 100-year pre-development flow rate. The top of bank for the detention basin shall be set at least one foot above this elevation. The lowest finished floor elevation of adjacent structures shall also be at least one foot above the detention basin top of bank.
(B) Detention storage requirements. See division (A) above.
(C) Drainage system design and evaluation. The following criteria should be used in evaluating and designing the drainage system. The design will provide capacity to pass the ten-year peak flow rate in the minor drainage system and an overload flow path for flows in excess of the design capacity.
(1) Design methodologies. Detention basin design shall be calculated using NRCS TR-55 methods. Basins with drainage areas of ten acres or less may be calculated using the rational method as approved by the Illinois Department of Transportation. Other applicable methods, i.e., HEC-1, TR-20, SWMM and the like shall be used for large watersheds.
(2) Positive drainage. When practical, all developments must be provided an overland flow path that will pass the 100-year, 24-hour event flow at a stage at a stage at least one foot below the lowest grade, adjacent to a structure, in the vicinity of the flow path. Street ponding and flow depths shall not exceed curb heights.
(D) Rainfall. Unless a continuous simulation approach to drainage system hydrology is used, all design rainfall events shall be based on the Illinois State Water Survey’s Bulletin 70.
(1) The first quartile point rainfall distribution shall be used for the design and analysis of conveyance systems with critical durations less than or equal to six hours.
(2) The second quartile distribution shall be used for storms with durations greater than six hours and less than or equal to 12 hours.
(3) The third quartile point rainfall distribution shall be used for the design and analysis of detention basins and conveyance system with critical durations greater than 12 and less than or equal to 24 hours.
(4) The fourth quartile distribution shall be used in the design and analysis of systems with durations greater than 24 hours.
(5) The first, third and fourth quartile distributions described by Huff are presented in Table 37 of Bulletin 70. Refer to Table 13 of Bulletin 70 for rainfall depth, duration and frequency. The NRCS Type II distribution may be used as an alternate to the Huff distributions. The total rainfall value for the design storm shall be adjusted for the “St. Louis Urban Effect” as given in Table 4, Illinois State Water Survey Circular 172.
(E) Antecedent moisture. Average antecedent moisture conditions shall be assumed when calculating runoff curve numbers for use in the NRCS TR-55 method.
(F) Wet detention basin design. Wet detention basins shall be designed to remove storm water pollutants, to be safe, to be aesthetically pleasing, and as much as feasible to be available for recreational use.
(1) Wet basin depths. Wet basins shall be at least three feet deep, excluding nearshore banks and safety ledges. If fish habitat is to be provided they shall be at least eight feet deep over 25% of the bottom area to prevent winterkill.
(2) Wet basin shoreline slopes. The side slopes of wet basins at the normal pool elevation shall not be steeper than three to one (3 to 1 horizontal to vertical). It is recommended that aquatic vegetation be established around the perimeter to provide protection from shorelines erosion. For basins in excess of five acres, riprap shoreline protection shall be provided.
(3) Permanent pool volume. The permanent pool volume in a wet basin at normal depth shall, at a minimum, be equal to the runoff volume from its watershed for the two-year, 24-hour event (calculated during dry weather conditions).
(4) Wet basin inlet and outlet orientation. The distance between detention inlets and outlets shall be maximized. Inlets and outlets shall be at opposite ends of the basin providing that the orientation does not create undue hardship based on topography or other natural constraints.
(G) Dry detention basin design. In addition to the other requirements of this chapter, dry basins shall be designed to remove storm water pollutants, to be safe, to be aesthetically pleasing and as much as feasible to be available for multiple uses. Paved low flow channels may be used in a dry basin provided provisions are made to prevent ponding.
(H) (1) Dry basin drainage. Dry basins shall be designed so that 80% of their bottom area shall have standing water no longer than 72 hours for any runoff event less than the 100-year, 24-hour event. Grading plans shall clearly distinguish the wet portion of the basin bottom. Underdrains directed to the outlet may be used to accomplish this requirement.
(2) Velocity dissipation. Velocity dissipation measures shall be incorporated into dry basin designs to minimize erosion at inlets and outlets and to minimize resuspension of pollutants.
(3) Dry basin inlet and outlet orientation. Shall be the same as division (F)(4) above.
(I) Existing depressional areas. Existing depressional storage volume will be maintained and the volume of detention storage provided to meet the requirements of this chapter shall be in addition to existing storage.
(J) Minimum detention outlet size. Where a single pipe outlet orifice plate is to be used to control discharge, it shall have a minimum diameter of 12 inches for larger basins. Smaller basins may install a smaller rectangular or v-notch weir to control discharge. If this minimum orifice size permits release rates greater than those specified in this section, and regional detention is not a practical alternative, outlets, structures such as perforated risers, or flow control orifices shall be used.
(K) (1) Detention in floodplains. The placement of detention basins within the floodplain is strongly discouraged because of questions about their reliable operation during flood events. However, the storm water detention requirements of this chapter may be fulfilled by providing detention storage within flood fringe areas on the project site provided the following provisions are met as well as compliance with § 153.002.
(2) Detention in flood fringe areas. The placement of a detention basin in a flood fringe area shall require compensatory storage for one and one-half times the volume below the base flood elevation occupied by the detention basin including any terms. The release from the detention storage provided shall still be controlled consistent with the requirements of this section. The applicant shall demonstrate its operation for all streamflow and floodplain backwater conditions.
(a) Excavations for compensatory storage along watercourses shall be opposite or adjacent to the area occupied by detention.
(b) All floodplain storage lost below the existing ten-year flood elevation shall be replaced below the existing ten-year elevation. All floodplain storage lost above the existing ten-year elevation shall be replaced above the existing ten-year flood elevation. All compensatory storage excavations shall be constructed to drain freely and openly to the watercourse and comply with § 153.002.
(3) Detention on prime farmland. The placement of detention basins shall avoid the utilization of prime farmland. All detention basin construction shall examine potential impacts to adjacent agricultural land and shall address measures that will be implemented to eliminate such impacts and comply with § 153.002.
(4) Detention in floodways. Detention basins shall be placed in the floodway only in accordance with division (K)(1) above.
(5) On-stream detention. On-stream detention basins are discouraged but allowable if they provide regional public benefits and if they meet the other provisions of this chapter with respect to water quality and control of the 100-year 24-hour events from the property. Further criteria are presented in § 153.039. If on-stream detention is used in watersheds larger than one square mile, the applicant will use hydrographic modeling to demonstrate that the design will not increase the water level for any properties upstream or downstream of the property. Also, impoundment of the stream as part of on-stream detention shall:
(a) Not prevent the migration of indigenous fish species, which require access to upstream areas as part of their life cycle, such as for spawning;
(b) Not cause or contribute to the degradation of water quality or stream aquatic habitat;
(c) Include a design calling for gradual bank slopes, appropriate bank stabilization measures and a pre-sedimentation basin;
(d) Not involve any stream channelization or the filling of wetlands;
(e) Require the implementation of an effective non-point source management program throughout the upstream watershed which shall include as a minimum: runoff reduction best management practices (BMPs) consistent with § 153.036; two-year, 24 hour detention/sedimentation basin for all development consistent with this division (K)(5);
(f) Not occur downstream of a wastewater discharge;
(g) Not contribute to the duration or flood frequency of any adjacent land; and
(h) Comply with § 153.002.
(L) Drainage into wetlands, rivers, streams, lakes, ponds and depressional storage areas. Wetlands, lakes, ponds and depressional storage areas shall be protected from damaging modifications and adverse changes in runoff quality and quantity associated with land developments. In addition to the other requirements of this chapter, the following requirements shall be met for all developments whose drainage flows into wetlands, rivers, lakes, ponds or depressional storage areas.
(1) Detention in wetlands, rivers, streams, lakes, ponds or depressional storage areas. Existing wetlands, rivers, lakes, ponds or depressional storage areas shall not be modified for the purpose of storm water detention unless it is demonstrated that the proposed modifications will maintain or improve its habitat and ability to perform beneficial functions and shall comply with § 153.002. Existing storage and release rate characteristics of wetlands, rivers, lakes, ponds or depressional storage areas shall be maintained and the volume of detention storage provided to meet the requirements of this section shall be in addition to this existing storage.
(3) Alteration of drainage patterns. Site drainage patterns shall not be altered to substantially decrease or increase the existing area tributary to the wetlands, rivers, lakes, ponds or depressional storage areas.
(4) Detention/sedimentation. All runoff from the development shall be routed through a preliminary detention/sedimentation basin designed to capture the two-year, 24-hour event and hold it for at least 24 hours, before being discharged to the wetland, river, lake, pond or depressional storage area. This basin shall be constructed before property grading begins and shall be maintained throughout the construction process. In addition, the drainage hierarchy defined in § 153.036 should be followed to minimize runoff volumes and rates being discharged to the wetland, river, stream, lake, pond or depressional storage area and as further regulated in and this section.
(5) Loessal soils. Care must be taken to avoid open flow discharges of storm water over silt (loessal) soils due to high potential for erosion.
(6) Sinkholes, karst area. The following requirements apply for new developments or redevelopments where sinkholes are determined to be present.
(a) A storm water detention basin shall not be placed in or over a sinkhole.
(b) Storm water detention basins shall not be located closer than 100 feet from the rim of a sinkhole.
(c) The outflow from a storm water detention basin, channel, ditch or any storm water runoff generated as a result of a new development or redevelopment shall not empty into or be directed, redirected by any means into or through any sinkhole.
(d) If, after the review of the storm water drainage plan, the Code Administrator may determine that more detailed information is required, a sinkhole evaluation may be required. A sinkhole evaluation which addresses the geologic, engineering and environmental factors resulting from a new development or redevelopment be performed by a professional with experience and expertise in karst topography, whom shall certify the results of the evaluation. This evaluation shall be the responsibility of the applicant and performed at no cost to the county. After a review of this evaluation and with the consultation of the County Soil and Water Conservation District, the County Code Administrator may either approve or disapprove the drainage plan as submitted.
(e) Whenever a new sinkhole appears or it becomes apparent that the sinkhole has not yet been identified, it shall be reported to the County Soil and Water Conservation District.
(f) Compliance with § 153.002 is required.
(M) Street detention, parking lot detention and culvert drainage.
(1) Street detention. If streets are to be used as part of the minor or major drainage system, ponding depths shall not exceed curb heights and shall not remain flooded for drainage system, ponding depths shall not exceed curb heights and shall not remain flooded for more than eight hours for any event less than or equal to the 100-year, 24-hour event.
(2) Parking lot detention. The maximum storm water ponding depth in any parking area shall not exceed six inches for more than four hours.
(3) Culvert, road and driveway crossings. Sizing of culvert crossings shall consider entrance and exit losses as well as tailwater conditions on the culvert.
(N) (1) Infiltration practices. To effectively reduce runoff volumes, infiltration practices including basins, trenches and porous pavement should be located in hydrologic soil groups “A” and “B” as designated by the U.S.D.A. Natural Resources Conservation Service. Infiltration basins and trenches designed to re-charge groundwater shall not be located within 75 feet of a water supply well or building foundation and comply with § 153.002. A sediment settling basin shall be provided to remove coarse sediment from storm water flows before they reach infiltration basins or trenches. Storm water shall not be allowed to stand more than 72 hours over 80% of the dry basin’s bottom area for the maximum design event to be exfiltrated. The bottom of infiltration basins or trenches shall be a minimum of four feet above the seasonally high groundwater and bedrock level. Engineering calculations demonstrating infiltration rates shall be included with the application.
(2) Vegetated filter strips and swales. To effectively filter storm water pollutants and promote infiltration of runoff sites should be designed to maximize the use of vegetated filter strips and swales. Whenever practicable, runoff from impervious surfaces should be directed onto filter strips and swales comprised of native grasses and forbs before being routed to a storm sewer or detention basin.
(O) Safety considerations. The drainage system components, especially all detention basins, shall be designed to protect the safety of any children or adults coming in contact with the system during runoff events and shall comply with § 153.002.
(1) Slide slopes. The side slopes of all detention basins at 100-year, 24-hour capacity shall be as level as practicable to prevent accidental falls into the basin and for stability and ease of maintenance. Side slopes of detention basins and open channels shall not be steeper than three to one (horizontal to vertical).
(2) Safety ledge. All wet detention basins shall have a level safety ledge at least four feet in width two and one-half to three feet below the normal water depth or must be protected by an enclosed fence, at least 48 inches in height.
(3) Velocity. Velocities throughout the surface drainage system shall be controlled to safe levels taking into consideration rates and depths of flow.
(4) Overflow structures. See division (A)(2) above.
(P) Maintenance considerations. The storm water drainage system shall be designed to minimize and facilitate maintenance. Turfed side slopes shall be designed to allow lawn mowing equipment to easily negotiate them. Wet basins shall be provided with alternate outflows which can be used to completely drain the pool for sediment removal. Pumping may be considered if drainage by gravity is not feasible. Presedimentation basins shall be included, where feasible, for localizing sediment deposition and removal. Site access for heavy equipment shall be provided.
(Ord. passed 9-8-2009)
(A) Storm water runoff from areas tributary to the property shall be considered in the design of the property’s drainage system.
(B) Whenever practicable, flows from upstream areas that are not to be detained should be routed around the basin being provided for the site being developed.
(1) Upstream areas not meeting chapter requirements.
(a) When there are areas not meeting the storage and release rates of this chapter, tributary to the applicant’s property, regionalized detention on the applicant’s property shall may be explored by the applicant or the county. When it is deemed beneficial by the county or the applicant to explore such a design, the following steps shall be followed:
2. Areas tributary to the applicant’s property, not meeting the storage and release rate requirements of this chapter, shall be identified; and
3. Using the areas determined above plus the applicant’s property area, total storage needed for the combined properties shall be computed.
(b) Allowable release rates shall be computed using the combined property areas. Storage shall be computed as described in § 153.038. If tributary areas are not developed, a reasonable fully developed land cover shall be assumed for the purposes of computing storage.
(c) Once the necessary combined storage is computed, the county may choose to pay for over-sizing the applicant’s detention basin to accommodate the regional flows. The applicant’s responsibility will be limited to the storage for his or her property as computed above. If regional storage is selected by the county then the design is produced in § 153.037 shall be implemented. If regional storage is rejected by the county, the applicant shall bypass all tributary area flows around the applicant’s basin whenever practicable. If the applicant must route upstream flows through his or her basin and the upstream areas exceed one-square mile in size, the applicant must meet the provision of § 153.038(K)(5) for on-stream basins.
(2) Upstream areas meeting chapter requirements. When there are areas which meet the storage and release rate requirements of this chapter, tributary to the applicant’s property, the upstream flows shall be bypassed around the applicant’s detention basin if this is the only practicable alternative. Storage needed for the applicant’s property shall be computed as described in division (B)(1) above. However, if the county decides to route tributary area flows through an applicant’s basin, the final design storm water releases shall be based on the combined total of the applicant’s property plus tributary areas. It must be shown that at no time will the release rate from the combined property exceed the allowable release rate for applicant’s property alone.
(Ord. passed 9-8-2009)
Where detention, retention or depressional storage areas are to be used as part of the drainage system for a property, they shall be constructed as the first element of the initial earthwork program. Any eroded sediment captured in these facilities shall be removed by the applicant on a regular basis and before project completion in order to maintain the design volume of the facilities.
(Ord. passed 9-8-2009)
SOIL EROSION AND SEDIMENT CONTROL
The county hereby finds that:
(A) The soil types found in the county are susceptible to erosion and left unprotected could cause severe loss of soil with resultant damage to property;
(2) The topography of the county contains areas with steep slopes upon which, if clearing of trees and/or inappropriate construction takes place, could result in severe erosion and slope stability problems which could result in damage to property;
(3) Excessive quantities of soil may erode from areas undergoing development for certain non-agricultural uses including, but not limited to, the construction of dwelling units, commercial buildings and industrial plants, the buildings of roads and highways, the modification of stream channels and drainage ways, and the creation of recreational facilities;
(4) The washing, blowing and falling of eroded soil across and upon roadways endangers the health and safety of users thereof, by decreasing vision and reducing traction of road vehicles;
(5) Soil erosion necessitates the costly repairing of gullies, washed out fills and embankments;
(6) Sediment from soil erosion tends to clog sewers and ditches and to pollute and silt rivers, streams, lakes, sinkholes, wetlands and reservoirs;
(7) Sediment limits the use of water and waterways for most beneficial purposes, promotes the growth of undesirable aquatic weeds, destroys fish and other desirable aquatic life, and is costly and difficult to remove; and
(8) Sediment reduces the channel capacity of waterways and the storage capacity of floodplains and natural depressions, resulting in increased chances of flooding at risk to public health and safety.
(Ord. passed 9-8-2009)
(A) It is the objective of this chapter to control soil erosion and sedimentation caused by development activities, including clearing, grading, stripping, excavating and filling of land in the county. Measures taken to control soil erosion and off-site sediment runoff shall be adequate to assure that sediment is not transported from the site by a storm event of ten-year, 24-hour frequency or less.
(B) The following principles shall apply to all new development or redevelopment activities within the county and to the preparation of the submissions required under § 153.057.
(1) New development or redevelopment shall be related to the topography and soils of the site so as to create the least potential for erosion. Areas of steep slopes greater than 33% where high cuts and fills may be required are to be avoided whenever possible, and natural contours should be followed as closely as possible.
(2) Natural vegetation shall be retained and protected wherever possible. Areas immediately adjacent to natural watercourses, lakes, ponds, sinkholes, and wetlands are to be left undisturbed wherever possible. Temporary crossings of watercourses, when permitted, must include appropriate stabilization measures.
(3) Special precautions shall be taken to prevent damages resultant from any necessary development activity within or adjacent to any stream, lake, pond, sinkhole or wetland. Preventive measures shall reflect the sensitivity of these areas to erosion and sedimentation.
(4) The smallest practical area of land should be exposed for the shortest practical time during development.
(5) Sediment basins or traps, filter barriers, diversions and any other appropriate sediment or runoff control measures shall be installed prior to site clearing and grading and maintained to remove sediment from run-off waters from land undergoing development.
(6) The selection of erosion and sediment control measures shall be based on assessment of the probable frequency of climatic and other events likely to contribute to erosion, and on evaluation of the risks, costs and benefits involved.
(7) In the design of erosion control facilities and practices, aesthetics and the requirements of continuing maintenance must be considered.
(8) Provisions shall be made to accommodate the increased run-off caused by changing soil and surface conditions during and after development. Drainage ways should be designed so that their final gradients and the resultant velocities and rates of discharge will not create additional erosion on-site or downstream.
(9) Permanent vegetation and structures shall be installed and functional as soon as practical during development.
(10) Those areas being converted from agricultural purposes to other land uses shall be vegetated with an appropriate protective cover prior to development.
(11) All waste generated as a result of site development activity shall be properly disposed of and shall be prevented from being carried off the site by either wind or water.
(12) All construction sites shall provide measures to prevent sediment from being tracked onto public or private roadways.
(13) All temporary soil erosion and sediment control practices shall be maintained to function as intended until the contributing drainage area has been permanently stabilized at which time they shall be removed.
(C) Water quality shall adhere to:
(1) Illinois Environmental Protection Act: 415 ILCS 5/11 and 5/12, from Ch.111-1/2, par 1011 and 1012;
(2) Illinois Pollution Control Board Rules and Regulations: Title 35: Environmental Protection, Subtitle C: Water Pollution, Chapter 1: Pollution Control Board, Part 302 Water Quality Standards; and
(3) Illinois Pollution Control Board Rules and Regulations: Title 35: Environmental Protection, Subtitle C: Water Pollution, Chapter I: Pollution Control Board, Part 304 Effluent Standards.
(Ord. passed 9-8-2009)
(A) Each applicant shall submit the information depending on development size, as regulated to ensure that the provisions of this chapter are met. The submittal shall include sufficient information to evaluate the environmental characteristics of the property, the potential adverse impacts of the development related to erosion both on-site and off-site, and the effectiveness of the proposed erosion and sediment control plan in reducing sediment loss and meet the provisions of § 153.002. The applicant shall certify on the drawing that all clearing, grading, drainage and construction shall be accomplished in strict conformance with the erosion and sediment control plan.
(B) The following information shall be submitted for both existing and proposed property conditions; new development or redevelopments meeting the requirements of § 153.003.
(2) Mapping and descriptions. The existing and proposed erosion and sediment control features of the property and immediate vicinity including:
(a) As required in § 153.035(B)(1), (B)(2) and (B)(3);
(b) Location of the slope disturbance line;
(c) Location and description of the erosion and sediment control measures to be employed during construction;
(d) 1. For any structures proposed to be located on the slope side of the slope disturbance line the map shall include the limits of disturbance including tree removal, erosion and sediment control measures during construction, cross-section view of any proposed cut or fill, erosion and sediment control measures during construction, details of method(s) proposed for providing slope stability, permanent storm water control measures and permanent erosion and sediment control measures all being certified by a registered professional engineer or a certified professional erosion control specialist; and
2. The predominant soil types on the site, their location and their limitations for the proposed use as defined by the U.S.D.A. Natural Resources Conservation Service.
(e) The proposed use of the site, including present and planned development, areas of clearing, stripping, grading, excavation and filling; proposed contours, finished grades, and street profiles; the storm water plan as required in §§ 153.035 through 153.040; kinds and locations of utilities, areas and acreages proposed to be paved, sodded or seeded, vegetatively stabilized, or left undisturbed; and the location of specimen trees over 18 inches in diameter and their type;
(f) The erosion and sediment control plan showing all measures necessary to meet requirements of this chapter throughout all phases of construction and those remaining permanently after completion of the development of the site, including:
1. Location and description, including standard details, of all sediment control measures, runoff control measures, including diversions, waterways and outlets, and design specifics of sediment basins and traps including outlet details;
2. Location and description of all soil stabilization and erosion control measures, including seeding mixtures and rates, types of sod, method of seedbed preparation, expected seeding dates, type and rate of lime and fertilizer application, kind and quantity of mulching for both temporary and permanent vegetative control measures, and types of non-vegetative stabilization measures;
3. Location and description of methods to prevent tracking of sediment off-site including construction entrance details, as appropriate;
4. Description of dust and traffic control measures;
5. Locations of stockpiles and description of stabilization methods;
6. Location of off-site fill or borrow volumes, locations and methods of stabilization;
7. Provisions for maintenance of control measures, including type and frequency of maintenance, easements and estimates of the cost of maintenance; and
8. The proposed phasing of development of the site, including stripping and clearing, rough grading and construction, and final grading and landscaping.
a. Phasing should identify the expected date on which clearing will begin, the estimated duration of exposure of cleared area, and the sequence of installation of temporary sediment control measures (including perimeter controls), installation of storm water drainage, paving streets and parking areas, final grading and the establishment of permanent vegetative cover, and the removal of temporary measures.
b. It shall be the responsibility of the applicant to notify the Code Administrator of any significant changes which occur in the site development schedule after the initial erosion and sediment control plan has been approved.
(Ord. passed 9-8-2009)
(A) General. The preparation of soil erosion and sediment control plans shall follow the principles outlines in the Illinois Procedures and Standards for Urban Soil Erosion and Sedimentation Control, excepting Chapter Six published by the Urban Committee of the Association of Illinois Soil and Water Conservation Districts. The design criteria, standards and methods shall be prepared in accordance with the requirements of this chapter and the standards and specifications contained in Illinois Urban Manual prepared for the Illinois Environmental Protection Agency by the U.S.D.A. Natural Resources Conservation Service, which standards and methods are hereby incorporated into this chapter by reference. In the event of conflict between the provisions of said manuals and of this chapter, this chapter shall govern.
(B) Erosion and sediment control design requirements. New developments or redevelopments shall comply with § 153.057 and meet the following.
(1) Control measures shall be constructed to control runoff from the property to such an extent possible that sediment is retained on-site.
(2) Temporary on-site control measures required shall be constructed and functional prior to initiating clearing, grading, stripping, excavating or fill activities on the site.
(3) Disturbed areas shall be stabilized with permanent measures within seven calendar days following the end of active disturbance, or re-disturbance consistent with the following criteria.
(a) Appropriate permanent stabilization measures shall include seeding, mulching, sodding, with non-vegetative measures as a last resort.
(b) Areas having slopes greater than 33% shall be stabilized with sod, mat or blanket in combination with seeding or equivalent.
(4) All temporary and permanent erosion and sediment control practices must be maintained and repaired as needed to assure effective performance of their intended function.
(5) Site development requirements: on-site sediment control measures, as specified by the following criteria, shall be constructed as specified in the referenced handbooks, and functional prior to initiating clearing, grading, stripping, excavating or fill activities on the site.
(a) For new developments or redevelopments less than one acre, or for a tract of land where a single-family dwelling is being erected and less than 10,000 square feet of impervious surface is being developed, filter barriers (including filter fences, straw bales or equivalent control measures) shall be constructed to control all on-site runoff. Vegetated filter strips, with a minimum width of 25 feet, may be used as an alternative only where runoffs in sheet flow is expected.
(b) For new developments or redevelopments more than one acre but less than five acres, a sediment trap designed in accordance with the IEPA Standards and Specifications for Soil Erosion or equivalent control measures shall be constructed at the down slope point of the disturbed area.
(c) For new developments or redevelopments greater than five acres, a sediment basin or equivalent control measure shall be constructed at the down slope point of the disturbed area.
(d) Sediment basin and sediment trap designs shall provide for both “dry” detention and “wet” detention sediment storage. The detention storage shall be composed of equal volumes of “wet” detention storage and “dry” detention storage and each shall be sized as regulated in §§ 153.035 through 153.040. The release rate of the basin shall be that rate as regulated in §§ 153.035 through 153.040. The elevation of the outlet structure shall be placed such that it only drains the dry detention storage.
(e) The sediment storage shall be sized to store the estimated sediment load generated from the site over the duration of the construction period with a minimum storage equivalent to the volume or sediment generated in one year. For construction periods exceeding one year, the one-year sediment load and a sediment removal schedule may be substituted.
(f) The alteration of sinkholes by tilling, grading or excavating is prohibited, including an area within 25 feet from the rim.
(g) To the extent possible or as otherwise regulated in this chapter all desirable trees eight inches in diameter and larger shall be protected for their present and future value for erosion protection and other environmental benefits. Trees that have been selected for preservation shall be marked prior to the beginning of any clearing, grading, stripping, excavation or filling of the site. A “no construction zone” shall be established and marked at the perimeter of the drip line of each tree which is to be preserved.
(6) Storm water conveyance channels, including ditches, swales and diversions, and the outlets of all channels and pipes shall be designed and constructed as regulated in §§ 153.035 through 153.040. All constructed or modified channels shall be stabilized within 48 hours, consistent with the standards as required in the IEPA Erosion Control Manual: Standards and Specifications for Soil Erosion and Sediment Control.
(2) Construction vehicles shall be kept out of the stream channel to the maximum extent practicable. Where construction crossings are necessary, temporary crossings shall be constructed of non-erosive material, such as riprap or gravel. The time and area of disturbance of stream channels shall be kept to a minimum. The stream channel, including bed and banks, shall be stabilized within 48 hours after channel disturbance is completed, interrupted or stopped.
(8) Storm sewer inlets and culverts shall be protected by sediment traps or filter barriers meeting accepted design standards and specifications.
(9) Soil storage piles containing more than ten cubic yards of material shall not be located with a down slope drainage length of less than 25 feet to a roadway, drainage channel or sinkhole. Filter barriers, including straw bales, filter fence or equivalent, shall be installed immediately on the down slope side of the piles.
(a) If dewatering devices are used, discharge locations shall be protected from erosion. All pumped discharges shall be routed through appropriately designed sediment traps or basins, or equivalent and shall not be deposited into a sinkhole.
(b) Each site shall have graveled (or equivalent) entrance roads, access, drives and parking areas of sufficient length and width to prevent sediment from being tracked onto public or private roadways. Any sediment reaching a public or private road shall be removed by shoveling or street cleaning (not flushing) before the end of each workday and transported to a controlled sediment disposal area.
(Ord. passed 9-8-2009)
All soil erosion and sediment control measures necessary to meet the requirements of this chapter shall be maintained periodically by the applicant or subsequent land owner during the period of land disturbance and development of the site in a satisfactory manner to ensure adequate performance.
(Ord. passed 9-8-2009)
All waste materials generated during construction activities must be properly disposed. Examples of construction site waste may consist of, but not be limited to, all building materials, raised structure debris, concrete (including concrete truck wash), asphalt, brick, excess soil, rebar, erosion and sediment control materials, cleared vegetation, chemicals, temporary bathroom facilities and all other construction site wastes.
(Ord. passed 9-8-2009)
(A) Plan.
(1) Activities that are applicable to this chapter, per § 153.003, must provide a construction site storm water pollution prevention plan (CSSPPP).
(2) The construction site storm water pollution prevention plan may be a full sized plan sheet with necessary notes for requirements or may be a narrative explaining construction site operating procedures to minimize or eliminate storm water pollution as a result of construction activities.
(3) The items covered in an approvable CSSPPP are dependent on the activities and the materials required on site to complete the project. Therefor, the detail of the plan may be more or less depending on-site activities planned.
(B) Standard items. Standard items included in a CSSPPP are, but at not limited to:
(1) Purpose;
(2) Construction site description;
(3) Activities/materials to be addressed in the CSSPPP;
(4) Construction site operating procedures;
(5) Activities/materials monitoring and maintenance; and
(6) Emergency and spill procedures.
(C) Change during construction. Should construction site activities/materials change during construction, the CSSPPP must reflect the changes. Therefor, the plan must be kept on-site at all times and be altered as necessary with the approval of the Inspector. Should major changes be warranted, a revised plan must be submitted for review and approval.
(Ord. passed 9-8-2009)
LONG-TERM MAINTENANCE RESPONSIBILITY
Maintenance of storm water drainage, and erosion and sediment control facilities located on private property shall be the responsibility of the owner of that property. Before an appropriate permit is obtained from the county, the applicant shall execute a maintenance agreement with the county guaranteeing that the applicant and all future owners of the property will maintain its storm water drainage and erosion and sediment control system and shall provide for access to the system for inspection by authorized personnel of the county. The maintenance agreement shall also stipulate that if the appropriate personnel of the county notify the property owner in writing of maintenance problems which require correction, the property owner shall begin such corrections within 24 hours and shall not extend beyond seven calendar days of such notification. If the corrections are not made within this time period, the county may have the necessary work completed and assess the cost to the property owner. The county has the option of requiring a bond to be filed by the property owner for maintenance of the storm water drainage and erosion and sediment control system.
(Ord. passed 9-8-2009)
Loading...