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AN ORDINANCE ADOPTING NEW VILLAGE CODE PROVISIONS REGARDING STORMWATER, FLOODPLAIN, AND SEDIMENTATION AND EROSION CONTROL REGULATIONS
OF THE VILLAGE OF OAK BROOK
WHEREAS, the Village of Oak Brook, Illinois ("Village") is located almost entirely within DuPage County, which adopted a Countywide Stormwater and Flood Plain Ordinance, ( “County Ordinance”) on September 24, 1991, in accordance with Illinois Compiled Statutes, Chapter 34, paragraph 5-1062; and
WHEREAS, on May 14, 2019, the County Board of the County of DuPage, Illinois, adopted a County Ordinance imposing regulations on stormwater and flood plain management; and
WHEREAS, in order for the Village to impose its own stormwater and floodplain regulations, the Village’s regulations on stormwater and floodplain management must comply with various requirements contained in the County Ordinance; and
WHEREAS, the Village’s regulations on stormwater and floodplain management are contained in Title 9 of the Village Code of the Village of Oak Brook, Illinois ( “Village Code” ); and
WHEREAS, the Village Board has determined that it would be in the best interests of the Village anditsresidentstoamendsectionsofTitle9oftheVillageCodesothatitconformstotherequirementsof the County Ordinance;and
NOW, THEREFORE, BE IT ORDAINED BY THE PRESIDENT AND BOARD OF TRUSTEES OF THE VILLAGE OF OAK BROOK, DU PAGE AND COOK COUNTIES, ILLINOIS, as follows:
Section 1. Recitals. The foregoing recitals are hereby incorporated into, and made part of, this Ordinance as the findings of the President and Board of Trustee of the Village of Oak Brook.
Section 2. Repeal and Replacement of Sections of Title 9 of the Village Code. Title 9, entitled “Stormwater, Floodplain, and Sedimentation and Erosion Control Regulations”, shall be, and is hereby, amended as specified in Exhibit A attached hereto and incorporated herein.
Section 3. Severability. If any section, paragraph, clause or provision of this Ordinance shall be held invalid, the invalidity thereof shall not affect any of the other provisions of this Ordinance.
Section 5. Effective Date. This Ordinance shall be in full force and effect from and after its passage, approval, and publication in the manner provided by law.
[SIGNATURE PAGE FOLLOWS]
AnOrdinanceAdopting Village Code ProvisionsRegarding
Stormwater, Floodplain, and Sedimentation and ErosionControl
Page 2 of3
APPROVED THIS 11th day of June, 2019.
Gopal G. Lalmalani
PASSED THIS 11th day of June, 2019.
Charlotte K. Pruss
AnOrdinanceAdopting Village Code ProvisionsRegarding
Stormwater, Floodplain, and Sedimentation and ErosionControl
Page 3 of3
Stormwater, Floodplain, and Sedimentation and Erosion Control Regulations
DuPage County Countywide Stormwater And Flood Plain Ordinance
Adopted by the County Board of the County of DuPage, Illinois on the 24th day of September 1991.
Revised by the County Board on the 14th day of June 1994. Revisions effective
the 1st day of September 1994.
Revised by the County Board on the 23rd day of April 1996. Revisions effective the 23 rd day of April 1996.
Revised by the County Board on the 12th day of November 1997. Revisions effective the 1st day of February 1998.
Revised by County Board on the 22nd day of June 1999. Revisions effective the 1st day of September 1999.
Revised by the County Board on the 13th day of June 2000. Revisions effective the 13th day of June 2000.
Revised by the County Board on the 25th day of March 2003. Revisions effective the 25th day of March 2003.
Revised by the County Board on the 27th day of January 2004. Revisions effective the 27th day of January 2004.
Revised by the County Board on the 8th day of June 2004. Revisions effective the 1st day of July 2004.
Revised by the County Board on the 8th day of March 2005. Revisions effective the 8th day of March 2005.
Revised by the County Board on the 28th day of February 2006. Revisions effective the 28th day of February 2006.
Revised by the County Board on the 25th day of March 2008. Revisions effective the 1st day of August 2008.
Revised by the County Board on the 24th day of April 2012. Revisions effective the 25 th day of April2012.
Revised by the County Board on the 23 rd day of April 2013. Revisions effective the 23 rd day of April2013.
Revised by the County Board on the 1214 th day of Marchy 2019. Revisions effective the1214 th day of Marchy 2019.
COUNTY OF DUPAGE, ILLINOIS
COUNTYWIDE STORMWATER AND FLOOD PLAIN ORDINANCE
Adopted As Appendix F
To The DuPage County Stormwater Management Plan
Table of Contents
ARTICLEI. AUTHORITYANDPURPOSE 1
ARTICLEII. ADMINISTRATION 6
ARTICLEIII. GENERALPROVISIONS 13
ARTICLEIV. STORMWATERMANAGEMENTCERTIFICATIONS 17
ARTICLEV. CERTIFICATIONSUBMITTALS 27
ARTICLEVI. PERFORMANCE SECURITYandEASEMENTS 34
ARTICLEVII. SOIL EROSION AND SEDIMENTCONTROLREQUIREMENTS 41
ARTICLE VIII. POST CONSTRUCTION BESTMANAGEMENTPRACTICES 45
ARTICLEIX. SITE RUNOFF CONVEYANCE, STORAGE &FIELDTILES 48
ARTICLEX. FLOOD PLAINMANAGEMENT 54
ARTICLEXI. WETLANDS 63
ARTICLEXII. BUFFERS 71
ARTICLEXIII. FEE-IN-LIEUPROGRAMS 74
ARTICLE XIV. PROHIBITEDACTS/ENFORCEMENT/PENALTIES 77
ARTICLEXV. APPEALS 84
ARTICLEXVI. VARIANCES 86
ARTICLE XVII. WAIVER COMMUNITIES 90
ARTICLE XVIII.MISCELLANEOUSPROVISIONS 95
APPENDIX A – ACRONYMS, INITIALISMSANDDEFINITIONS 99
APPENDIX B–PERFORMANCESTANDARDS 113
APPENDIX C– CERTIFICATIONFLOWCHARTS 114
EXHIBIT1 WATERSHED PLANNINGAREA MAP 119
EXHIBIT2 LIST OF DESIGNATED FLOODWAY/FLOODPLAINMAPS 120
SCHEDULEA PERMIT FEE
SCHEDULE B SITE RUNOFF STORAGE VARIANCE AND BMP FEE-IN-LIEU SCHEDULE. 157150
15-1. Statutory Authority
15-1.A This Ordinance shall be known, and may be cited, as the DuPage County Countywide Stormwater and Flood Plain Ordinance.
15-1.B The DuPage County Stormwater Management Planning Committee (the "Committee") and the DuPage County Board promulgate this Ordinance pursuant to their authority to adopt ordinances regulating Flood Plain management and governing the location, width, course, and release rate of all stormwater runoff Channels, streams, and basins in DuPage County, in accordance with the adopted DuPage County Stormwater Management Plan (the "Plan"). The statutory authority for this Ordinance is contained in 55 ILCS 5/ ¶¶ 5-1041, 5-1042, 5-1049, 5-1062, 5-1063, 5-1104, 5-12003, and 5-15001 et seq.; and 415 ILCS5/43, and other applicable authority, all as amended from time to time.
15-1.C As applicable, the municipalities within DuPage County promulgate and enforce this and other relevant Stormwater Management Ordinances pursuant to 65 ILCS 5/1-2-1, 5/11-12-12, 11-30-2, 11-30-8, and 5/11- 31-2.
15-2. DuPage County Stormwater Management Plan. The Plan was recommended by the Committee and adopted by the DuPage County Board, after review by the appropriate agencies and public hearing, as Ordinance No. OSM-0001-89. The Plan is available for public inspection in the office of the DuPage County Clerk.
15-3. Findings. The Committee and the DuPage County Board hereby find that:
15-3.A Inappropriate use of the Flood Plain and Development have increased
Flood risk, Flood damage, and environmental degradation; and
15-3.B It is necessary to consider stormwater management on a Watershed
15-3.C DuPage County drains poorly because of flat topography and soils of low permeability; and
15-3.D The costs of increasing Channel capacity are prohibitive; and
15-3.E Many land development practices upset the natural hydrologic balance of DuPage County streams; and
15-3.F Most Flood damage occurs to Structures developed adjacent to streams in the Flood Plain or Floodway; and
15-3.G Wetlands represent a significant portion of the natural Watershed storage in DuPage County, and Wetlands play an essential role in Flood storage, conveyance, sediment control, and water quality enhancement; and
15-3.H Many stormwater management facilities are not adequately maintained; and
15-3.I The authority for control of Stormwater Facilities is widely distributed to many entities in DuPage County; and
15-3.J There are many strong local stormwater management programs; an
15-3.K Inconsistent enforcement of stormwater regulations contributes to the extent and severity of Flood damage.
15-4. Purposes of this Ordinance
15-4.A The principal purpose of this Ordinance is to promote effective, equitable, acceptable, and legal stormwater management measures. Other purposes of this Ordinance include:
15-4.A.1 Managing and mitigating the effects of urbanization on stormwater drainage throughout DuPage County; and
15-4.A.2 Reducing the existing potential for stormwater damage to public health, safety, life, and property; and
15-4.A.3 Protecting human life and health from the hazards of
Flooding and degradation of water quality; and
15-4.A.4 Protecting and enhancing the quality, quantity, and availability of surface and groundwater resources; and
15-4.A.5 Preserving and enhancing existing Wetlands, Buffers and aquatic environments, and encouraging restoration of degraded areas; and
15-4.A.6 Controlling sediment and erosion in and from Stormwater Facilities, Developments, and construction sites; and
15-4.A.7 Preventing the further degradation of the quality of ground and surface waters; and
15-4.A.8 Requiring appropriate and adequate provision for site runoff control, especially when the land is developed for human activity; and
15-4.A.9 Requiring the design and evaluation of each site runoff control plan consistent with Watershed capacities; and
15-4.A.10 Encouraging the use of stormwater storage in preference to stormwater conveyance; and
15-4.A.11 Lessening the taxpayers' burden for Flood-related disasters, repairs to Flood-damaged public facilities and utilities, and Flood rescue and relief operations; and
15-4.A.12 Meeting the Illinois Department of Natural Resources, Office of Water Resources' Floodway permitting requirements delineated in 615 ILCS 5/18g ("An Act in Relation to the Regulation of the Rivers, Lakes and Streams of the State of Illinois"), as amended from time to time; and
15-4.A.13 Making federally subsidized Flood insurance available to individual communities and for property throughout the County; and
15-4.A.14 Complying with the rules and regulations of the National Flood Insurance Program codified in Title 44 of the Code of Federal Regulations; and
15-4.A.15 Encouraging cooperation between the County, communities, and other
governmental entities with respect to Flood Plain and stormwater management; an
15-4.A.16 Requiring cooperation and consistency in stormwater management activities within and between the units of government having stormwater management jurisdiction; and
15-4.A.17 Restricting future Development in the Flood Plain to facilities that will not adversely affect the Flood Plain environments or adversely affect the potential for Flood damage; and
15-4.A.18 Incorporating water quality and habitat protection measures in all stormwater management activities within DuPage County; and
15-4.A.19 Requiring regular, planned Maintenance of stormwater management facilities; and
15-4.A.20 Encouraging control of stormwater quantity and quality at the most site-specific or local level; and
15-4.A.21 Allowing the use of simple technologies whenever appropriate and realistic, but requiring the use of more sophisticated techniques when necessary to ensure the adequacy of stormwater controls; and
15-4.A.22 Providing a procedure by which communities throughout the County may petition the Committee to implement and enforce the provisions of this Ordinance or an ordinance consistent with, and at least as stringent as, this Ordinance; and
15-4.A.23 Requiring strict compliance with and enforcement of this Ordinance.
15-4.B The purposes of this Ordinance are consistent with the Plan.
15-4.C The purposes of this Ordinance will be implemented by its provisions.
15-5. Reference to Watershed Plans
15-5.A This Ordinance recognizes the integrated nature of the Watershed system and the need to study certain Flood control alternatives and other stormwater management functions on a Watershed-wide basis.
15-5.B The following six major Watershed divisions, shown on Exhibit 1, are identified for detailed Watershed studies:
15-5.B.1 Salt Creek Watershed; and
15-5.B.2 East Branch DuPage River Watershed; and
15-5.B.3 West Branch DuPage River Watershed; and
15-5.B.4 Sawmill Creek Watershed; and
15-5.B.5 Des Plaines River Tributaries Watershed; and
15-5.B.6 Fox River Tributaries Watershed
15-5.C Watershed Plans or Interim Watershed Plans shall be prepared and periodically updated for these six major Watersheds, to identify stormwater management projects and establish criteria for Development. Interim Watershed Plans may also be developed for sub-watersheds of the six major Watersheds for purposes of addressing Flood Mitigation or water quality. With respect to this Ordinance, Developments identified in Watershed Plans, Interim Watershed Plans, or other studies approved by the Committee and adopted by the County Board, shall be considered certifiable provide that and to the extent that the plan or study addressed Certification issues.
15-5.D Adopted Watershed Plans or Interim Watershed Plans which contain more specific criteria than the criteria established for Countywide application in this Ordinance shall govern over Countywide criteria. Such Watershed Plans, upon their completion, approval, and proper adoption, are hereby incorporated into this Ordinance without further act of the DuPage County Board.
15-5.E Watershed specific criteria established in such Watershed Plans or Interim Watershed Plans shall be set forth as a schedule to this Ordinance.
15-5.F The Countywide requirements of this Ordinance shall apply in all Watersheds unless superseded by more specific Watershed Certification criteria.
15-6. Waiver Community Enforcement – Authority. Pursuant to the authority established in 55 ILCS 5/5-1062, the provisions of this Ordinance, either in part or as a whole, shall not be enforced by the County in any Community located wholly or partly within the County on petition of such Community and after a finding of the Committee that such Community has a duly adopted stormwater management ordinance consistent with, and at least as stringent as, the Plan and this Ordinance, as they may be amended from time to time, or that such Community has duly adopted the provisions of this Ordinance.
15-7. Authority for Committee Action in a Waiver Community-Complaints
15-7.A The Committee may, at its discretion, direct the Department to investigate substantive complaints concerning the failure of a Waiver Community to implement or enforce its Waiver Community Ordinance.
15-7.B If, after investigation and hearing pursuant to the provisions of Sections 15-132 to 15-138, the Committee determines that such Waiver Community has failed in some significant way, or has repeatedly failed, to implement or enforce its Waiver Community Ordinance, then the Committee may revoke any previously granted Partial Waiver or Complete Waiver, and the provisions of this Ordinance shall have full force and effect and shall be enforced within the boundaries of such Waiver Community by the County.
15-8. Authority and Choice of Planning Jurisdiction
15-8. A Pursuant to the authority granted by 55 ILCS 5/ 5-1062(b), as amended, a Community that is located in more than one county has chosen, at the time of formation of the Stormwater Management Planning Committee, and based on Watershed boundaries, to participate in the stormwater management planning program of either or both of the counties.
15-8.B The following communities have expressed their intent to choose to be included within the jurisdiction of the Plan and this Ordinance: DuPage County portions only - Bartlett, Batavia, Bensenville, Bolingbrook, Burr Ridge, Chicago, Elk Grove Village, Hanover Park, Hinsdale, Lemont, Naperville, Oak Brook, Roselle, Schaumburg, and Woodridge; and for the entire Community - Wayne. The Committee shall include the above-listed communities within the scope of its planning and enforcement jurisdiction.
15-11. Interpretation of Terms and Words
15-11.A The terms and words used in this Ordinance or in a Waiver Community Ordinance shall be interpreted as follows:
15-11.A.1 Words used in the present tense include the future tense; and
15-11.A.2 Words used in the singular number include the plural number and words used in the plural number include the singular number; and
15-11.A.3 The words "shall", "will", and "must" are mandatory, not permissive; and
15-11.A.4 All distances, unless otherwise stated, shall be measured horizontally.
15-11.A.5 The phrases "Director or the Administrator", "Director, or the Administrator in a Waiver Community", or "Director, or Administrator in a Complete Waiver Community", refer to the individual responsible for the enforcement in the specific area.
15-11.A.6 All references to “he”, “him”, “his”, “she”, and “her” shall be construed as gender-neutral.
15-11.B Definitions of terms specific to this Ordinance, and a list of acronyms and initialisms are contained in Appendix A.
15-12. Responsibility for Administration
15-12.A The Committee, or the Oversight Committee in a Waiver Community, shall determine policy related to, and direct the enforcement of, this Ordinance or the Waiver Community's Ordinance, as applicable.
15-12.B The Director, or the Administrator in a Waiver Community, shall have the authority and responsibility for the administration of this Ordinance or the Waiver Community's Ordinance, as applicable. In performing his or her duties, the Director or the Administrator may delegate routine responsibilities to any named designee.
15-12.C Each Community shall remain solely responsible for its standing in the NFIP and for:
15-12.C.1 Maintaining records and submitting reports required for the NFIP, including Elevation Certificates, Floodproofing Certificates, and Lowest Floor elevations; and
15-12.C.2 Notifying the Director, and if required FEMA, OWR, USACE, the IEPA, and the USEPA of any proposed amendment to this Ordinance or the Waiver Community's Ordinance.
15-13. Duties of Director. The duties and functions of the Director shall include:
15-13.A Supervising the execution of this Ordinance; and
15-13.B Supervising the Development and revision of the appendices of the Plan for Committee and County Board approval and taking such actions as are reasonably necessary and proper to carry out the purposes and provisions of this Ordinance; and
15-13.C Authorizing Flood Plain delineations and support documentation from Partial Waiver communities for any FEMA Map Change, which Authorization may be done concurrent with submittal to OWR or its designee and FEMA; and
15-13.D Developing and maintaining Countywide regulatory maps; and
15-13.E Directing the application and review of complex Stormwater Management Certifications for any Community that requests such assistance; and
15-13.F Performing, in Non-Waiver communities, the duties which are assigned to the Administrator in Waiver communities to the extent consistent with other laws; and
15-13.G Reviewing and authorizing proposed Developments referred to the Department in Flood Plain, Wetlands and Buffers within Partial Waiver communities; and
15-13.H Keeping USACE, OWR and FEMA informed of Community waiver and ordinance status within 30 days after any changes in status; and
15-13.I Notifying the communities, and if required FEMA, OWR, USACE, the IEPA, and the USEPA of any amendments to the Plan or this Ordinance; and
15-13.J Maintaining and making available to Applicants a list of all adopted General Certifications; and
15-13.K Encouraging and conducting studies, investigations, and research relating to the physical, chemical, ecological, engineering, and other aspects of stormwater management.
15-14. Duties of Administrator in Waiver Community. The duties and functions of the Administrator shall include:
15-14.A Ensuring that copies of all stormwater related and applicable required federal, state, and regional permits or County approvals are received before work under a Stormwater Management Certification begins in those areas of a site under the jurisdiction of those agencies; and
15-14.B Verifying the existence of Flood Plain, Wetlands and Buffers for each application; and
15-14.C Receiving Authorization for Development in Flood Plains, Wetlands, and Buffers in Partial Waiver Communities prior to issuance of a Certification; and
15-14.D Reviewing and approving Authorizations and issuing any Certifications or notices required by the Waiver Community Ordinance; and
15-14.E Notifying the Director and owners of adjacent upstream, downstream, and potentially affected property, affected state and federal agencies, and Watershed basin communities, and publishing a notice in a local newspaper of any Variance requested from the provisions of the Waiver Community Ordinance; and
15-14.F Notifying the Director and all affected Persons defined in Section 15-14.E of this Ordinance of any alteration or relocation of a watercourse including application for a FEMA CLOMC and LOMC as required; and
15-14.G Providing for inspections of Developments as provided in Section 15-20 of this Ordinance under the terms of the Waiver Community's Ordinance; and
15-14.H Investigating complaints of Violations of the Waiver Community's Ordinance; and
15-14.I Notifying any Applicant for a Variance that granting the
Variance may result in increased rates for Flood insurance; and
15-14.J Notifying the Director and other jurisdictions of alleged
Violations of their Certification or permit programs; and
15-14.K Notifying violators within Regulatory Flood Plains that failure to comply with NFIP provisions could make them ineligible to receive Flood insurance; and
15-14.L Initiating any proceeding necessary to enforce the Waiver Community Ordinance; and
15-14.M Encouraging and conducting studies, investigations, and research relating to the physical, chemical, ecological, engineering, and other aspects of stormwater management; and
15-14.N Advise, consult and cooperate with other governmental agencies to promote the purposes of this Ordinance and the Waiver Community's Ordinance; and
15-14.O Maintaining for public inspection copies of all applications and submittals, federal and state permit documents, variation documentation, FEMA CLOMC and LOMC, and all other documents required pursuant to Article IV and V of this Ordinance as directed under the Waiver Community's Ordinance; and
15-14.P Sending copies of any application for a FEMA CLOMC and
LOMC to the Director; and
15-14.Q Receiving Authorization for Development in Flood Plains from the Director prior to Partial Waiver Community approval of any FEMA CLOMC and LOMC; and
15-14.R Sending a copy of any petition or request for a Variance from the terms of the Waiver Community Ordinance to the Committee before any such Variance is approved by the Oversight Committee; except in cases where the Variance from the Waiver Community Ordinance still meets or exceeds the requirements of this Ordinance; and
15-14.S Submitting the necessary information to the Director relating to Development to maintain Countywide regulatory maps and for supervision of the Ordinance. This includes, but is not limited to, copies of any Stormwater Management Certifications, or FEMA CLOMCs and LOMCs; and
15-14.T Maintaining documentation necessary on "cost of improvement" on Buildings in the Flood Plain, relating to the Substantial Improvements or Substantial Damage requirements of this Ordinance or the NFIP; and
15-14.U Maintaining and making available to Applicants a list of all General Certifications adopted within the Waiver Community.
15-15. Representative Capacity. In all cases when any action is taken by the Director or the Administrator, or his or her duly appointed designee, to enforce the provisions of this Ordinance or the Waiver Community's Ordinance, such action shall be taken either in the name of and on behalf of the County or of the Waiver Community, or the people of the State of Illinois, and neither the Director nor the Administrator, or his or her designee, in so acting for the County or the Waiver Community shall be rendered personally liable.
15-16. Oversight Committee
15-16.A An Oversight Committee shall be established to oversee the implementation and enforcement of the Waiver Community's Ordinance within its jurisdiction.
15-16.B The corporate authorities of a Community, or any representatives duly appointed by the corporate authorities, may serve as the Oversight Committee.
15-16.C The Oversight Committee, when considering appeals or
Variances, may request an opinion from the Director or the MEG.
15-17. Stormwater Management Certification Review and Director Authorization
15-17.A Stormwater Management Certification Review Responsibilities in Partial Waiver Communities. When a Community petitions for and is granted a Partial Waiver of Enforcement of this Ordinance, such Community shall have the authority to review and approve applications for Stormwater Management Certifications in all
areas under its jurisdiction, provided that:
15-17.A.1 A Partial Waiver Community shall send applications for Stormwater Management Certifications to the Director for review and “Authorization” signifying compliance with the applicable provisions of this Ordinance when a Development includes: sites with Wetlands on or within 100’ of the Development, Buffers, and sites which include Regulatory Flood Plain, with the following exceptions:
15-17.A.1.a. The Administrator in a Partial Waiver Community may determine that a Development Site does not contain a wetland, Buffer or Flood Plain. Further, the Administrator may also determine, without obtaining Authorization from the Director, that a wetland or Buffer is on the Development Site and that it will not be impacted by the Development based on information submitted by the Applicant.
15-17.A.1.b. The Administrator in a Partial Waiver Community may review, without submittal to the County, applications for Developments on sites that contain Regulatory Flood Plain/Floodway where no impact to the portion of the site containing Regulatory Flood Plain/Floodway is proposed. The Administrator may also review site specific Flood Plain determinations, and Developments in the Flood Plains, for drainage areas less than 640 acres where no Floodway has been designated.
15-17.A.2 Those applications for Development where the Administrator has submitted the application to the County for Authorization may, after the Director authorizes the application for Development, issue the Stormwater Management Certification if the application meets the requirements of this Ordinance or the Waiver Community's Ordinance, as applicable.
15-17.B Stormwater Management Certification Review Responsibilities in a Complete Waiver Community. When a Community petitions for and is granted a Complete Waiver of Enforcement of this Ordinance, such Community shall review and Certify, signifying compliance with this Ordinance, all applications for Development under all provisions of the Ordinance within the boundaries of its jurisdiction.
15-17.C Stormwater Management Certification Review Responsibilities in a Non-Waiver Community. When a Community does not petition for Waiver of Enforcement of this Ordinance, such Community shall have applications reviewed and certified by the Director, signifying compliance with all provisions of this Ordinance within the boundaries of the Community.
15-17.D Stormwater Management Certification Reviews. Overall responsibility for supervision of the review of all aspects of a Stormwater Management Certification Application under the jurisdiction of this Ordinance rests with the Administrator, however the Administrator shall ensure that technical reviews are under the supervision of a Professional Engineer meeting the requirements of Section 15-127.A.3.a.1 and 15-127.A.3.a.2 for Complete Waiver Communities and Section 15-127.A.3.b.1. for Partial Waiver Communities. The Administrator will also utilize, as the situation requires, the appropriate experts who must meet the requirements of Sections 15-127.A.3.a.3 and 15-127.A.3.a.4 for a Complete Waiver Community or Section 15-127.A.3.b.2 for a Partial Waiver Community to review those aspects of the Development lying outside of the Professional Engineer’s area of expertise in accordance with the following:
15-17.D.1 In a Partial Waiver Community the Professional Engineer may utilize a Person with expertise in plant ecology for design review and construction observation of PCBMP installations which rely upon vegetation for water quality or Runoff volume reduction. The Professional Engineer may utilize a Soil Scientist or geotechnical engineer, or other Person with significant applicable soils expertise for PCBMP installations which rely on infiltration for water quality improvement and volume reduction. The Professional Engineer will coordinate review comments on an application with those from the Director on the same Development.
15-17.D.2 In a Complete Waiver Community, the reviewing Professional Engineer shall provide a written opinion that the proposed Development meets the minimum requirements of this Ordinance. Wetland delineation and other wetland or Buffer related aspects outside the expertise of the Professional Engineer must be reviewed by an Environmental Scientist employed by the Community in accordance with Section 15- 127.A.3.a.3 who shall provide a written opinion on those matters within their area of expertise that the proposed Development meets the minimum requirements of this Ordinance.
15-17.D.3 In a non-waiver Community, the Director, or his designee, will determine the appropriate individuals to review the application and coordinate review comments.
15-18. Municipal Engineers Group. A Municipal Engineers Group (MEG) shall be established whose purpose will be to provide input to the Director for representation of communities on technical matters related to the Ordinance, recommend General Certification topics, review draft Ordinance revisions, review draft General Certifications, and discuss permitting issues where a recommendation is requested.
15-18.A The membership of the MEG shall consist of the Stormwater Administrators, or their designees, in each of the Communities who have opted into the DuPage County Stormwater Program. In all matters brought to the MEG for a vote, each Community shall have one vote exercised by the Administrator, or their designee.
15-18.B The MEG shall adopt bylaws covering at a minimum what constitutes a quorum and notice requirements, and meeting schedule.
15-18.C Issues considered by the MEG for a vote shall be listed on the agenda sent out in advance of the scheduled meeting. The MEG shall meet no less than once per calendar year.
15-18.D All votes by the MEG are advisory. Summaries of the discussions will be kept of all meetings.
15-20. Required Inspections
15-20.A Any Development constructed pursuant to a Stormwater Management Certification shall be subject to periodic inspections by the Director or the Administrator during construction to ensure conformity with Certification provisions and conditions.
15-20.B Unless otherwise provided by a valid and enforceable intergovernmental agreement, the Department shall inspect and monitor the construction and Maintenance of Mitigation measures prepared pursuant to Articles XI and XII of this Ordinance for all mitigated Wetlands and Buffers authorized by a Stormwater Management Certification in a Non-Waiver or Authorization in a Partial Waiver Community.
15-23. Scope of Regulation
15-23.A This Ordinance, or the applicable Waiver Community Ordinance, shall apply to all Development of property within the boundaries of the County since February 15, 1992, including those under the control of any governmental entity, except State and Federal government agencies of higher jurisdiction or authority.
15-23.B The provisions of this Ordinance, or the applicable Waiver Community Ordinance, shall not apply to:
15-23.B.1 Structures and land uses existing as of February 15,1992 except when subsequently re-developed, and except that minimum standards of the NFIP shall apply to all Development; and
15-23.B.2 Proposed Developments that are listed on the Official List of Exempt Developments submitted by each Community. All such Developments on the list shall have met at least one of the following criteria:
15-23.B.2.a. Building permits for such Development were issued prior to February 15, 1992; or
15-23.B.2.b. Engineering of all Stormwater Facilities for such Development was submitted to and approved by the Community engineer prior to February 15, 1992; or
15-23.B.2.c. Annexation agreements or ordinances or other agreements were recorded or executed prior to February 15,1992 which specifically exempt such Development from Community codes; or
15-23.B.2.d. For other Developments, contractual agreements executed prior to February 15, 1992 which specifically exempt such Development from Community codes; or
15-23.B.2.e. Approvals resulting from judicial decrees preclude application of this Ordinance.
15-23.C The exemption granted pursuant to Section 15-23.B.2 shall extend only to the specific improvements authorized by the building permit, engineering approval, or judicial decrees, and all specific limitations agreed to in any annexation agreement or ordinance or contract shall apply. All other Development not previously specifically exempted shall remain subject to the provisions of this Ordinance or the applicable Waiver Community Ordinance.
15-23.D Plan changes which result in greater impervious coverage of the site compared to the exempted plan will be cause for the Director or Administrator to remove the Development from the Official List. Such a finding may be appealed to the Committee in accordance with Article XV for final decision.
15-23.E Nonconforming Structures shall not be replaced or enlarged in any manner unless such replacements or enlargements conform to the requirements of this Ordinance or the applicable Waiver Community Ordinance.
15-24. Official Lists of Exempt Developments
15-24.A Each revision to the Official List of Exempt Developments shall be approved by an official action of the corporate authorities of the Community, and shall be acknowledged in writing by the Director on behalf of the Committee.
15-24.B The Committee may challenge any revision of an Official List of Exempt Developments submitted by a Community within 60 days after proper submission of such list or revision. The Committee shall state in writing its reasons for rejection of any Development as not being in accordance with the provisions of Section 15-23.B.2 of this Ordinance.
15-24.C The Community may add a Development to, or delete a Development from, the Official List of Exempt Developments if an Applicant shows that the criteria listed in Section 15-23.B.2 of this Ordinance have been met or if the Community has determined that the criteria listed in Section 15-23.B.2 of this Ordinance have not been met.
15-24.D Prior to resubmitting its Official List of Exempt Development to the Committee deleting a Development, the Community resubmitting such list with such deletion shall notify the affected owner or Developer of such deletion in writing and provide such owner or Developer an opportunity to respond to the Community.
15-25.A This Ordinance and the Waiver Community Ordinances shall be liberally construed to protect the health, welfare, safety, and the environment of the residents of the County and to effectuate the purposes of this Ordinance and the Waiver Community Ordinances and the enabling legislation.
15-25.B Nothing contained in this Ordinance, or the Waiver Community Ordinances, shall be deemed to consent to, license, permit to locate, construct, or maintain any Structure, site, facility or operation, or to carry on any trade, industry, occupation, or activity.
15-25.C When provisions of this Ordinance, or any Waiver Community Ordinance, differ from any other applicable statute, law, ordinance, regulation, or rule, the more stringent provision shall apply.
15-25.D The provisions of this Ordinance and the Waiver Community Ordinances are cumulative and shall be considered additional limitations on all other laws and ordinances previously approved or that may hereafter be approved and that concern any subject matter included in this Ordinance or any Waiver Community Ordinance.
15-25.E Interpretation of technical provisions of this Ordinance shall be made by the Director, or the Administrator in a Waiver Community who may also consult the MEG for an advisory opinion.
15-26. Warning and Disclaimer of Liability
15-26.A The degree of Flood protection provided by this Ordinance or any Waiver Community Ordinance is considered reasonable for regulatory purposes and is based on engineering experience and scientific methods of study.
15-26.B Increased Flooding may result from causes beyond the control of the County or any Community.
15-26.C This Ordinance and the Waiver Community Ordinances do not, therefore, imply that areas outside the delineated Flood Plain or permitted land uses within the delineated Flood Plain will be free from Flooding and associated damages.
15-26.D Neither this Ordinance nor any Waiver Community Ordinance shall be construed or applied in any manner to create liability on the part of or a cause of action against the County, any Community, or any elected official, officer, agent, or employee thereof, for any Flood damage resulting from reliance on the provisions of this Ordinance or any Waiver Community's Ordinance or from reading or interpreting any map that is part of this Ordinance or any Waiver Community Ordinance.
15-27. General Stormwater and Flood Plain Requirements. The following general stormwater and Flood Plain requirements shall apply to all Development.
15-27.A Development shall not:
15-27.A.1 Result in unreasonable new or additional expense to any Person other than the Developer for Flood protection or for lost environmental stream uses and functions attributable to the Development; nor
15-27.A.2 Unreasonably increase Flood elevations or decrease Flood conveyance capacity upstream or downstream of the area under the ownership or control of the Developer; nor
15-27.A.3 Pose any unreasonable new or additional increase in Flood velocity or impairment of the hydrologic and hydraulic functions of streams and Flood Plains unless a Watershed Benefit is realized; nor
15-27.A.4 Violate any provision of this Ordinance or any applicable Waiver Community Ordinance either during or after construction; nor
15-27.A.5 Unreasonably or unnecessarily degrade surface or ground water quality.
15-27.B For purposes of this article, changes in Flood elevations or changes in discharges, within the limits of modeling tolerance allowed in this Ordinance, shall be deemed acceptable.
15-27.C Analysis and design of all stormwater and Flood Plain facilities required for Development shall:
15-27.C.1 Meet the standards and criteria established in the Plan and, if available, in Watershed Plans or in Interim Watershed Plans; and
15-27.C.2 Be consistent with techniques specified in the Watershed Plans or the Interim Watershed Plans; and
15-27.C.3 Site runoff storage and Compensatory Storage facilities shall be either constructed before or concurrently with general construction. The facilities shall be functional prior to or concurrent with any Building construction that increases a site’s Total Impervious Area.
15-28. Building Protection
15-28.A Within the boundary of the Regulatory Flood Plain, all Usable Space in new Buildings, or added to existing Buildings, shall either be elevated, Floodproofed, or otherwise protected such that the lowest entry shall be at least one foot above the nearest Base Flood Elevation to prevent the entry of surface stormwater. Floodproofing devices shall be operational without human intervention. If electricity is required for protection against Flood damage, there shall be a backup power source which will activate without human intervention. Floodproofing measures shall be certified by a Professional Engineer.
15-28.B All Usable Space in new Buildings or added to existing Buildings, shall be elevated, Floodproofed, or otherwise protected to at least one foot above the design elevation to prevent the entry of surface stormwater. The design elevation is the higher elevation of either Article X or the elevation associated with the design rate as determined in Section 15-73.A.2.
15-28.C Other Building protection standards for Structures that shall be implemented in the Flood Plain are listed in Section 15-81.B in Article X.
15-30. Stormwater Management Certifications. Any Person proposing a Development shall obtain a Stormwater Management Certification, or the Development must fit all conditions of a General Certification (Section 15- 32), or if applicable, obtain a Letter of Permission (Section 15-31) unless the Development meets all of the criteria of Section 15-30.A or one of the following criteria of Section 15-30.B.
15-30.A The Development is:
15-30.A.1 On a Development Site that does not include Flood Plain, Wetlands or Buffers; and
15-30.A.2 The Development does not add 2,500 square feet or more of Net New Impervious Area compared to the pre- Development conditions, and
15-30.A.3 Does not include 5,000 square feet or more of land disturbing activities.
15-30.B The Development Site does not include Wetlands, Buffers or
Flood Plains and consists solely of one or more of the following:
15-30.B.1 Cultivation, conservation measures or gardening; or
15-30.B.2 Installation, renovation or replacement of a septic system, potable water service line, or other utility to serve an existing Structure; or
15-30.B.3 Excavation or removal of vegetation in rights-of-way or public utility easements for the purpose of installing or maintaining utilities; or
15-30.B.4 Maintenance, repair or at grade replacement of existing lawn areas not otherwise requiring a Stormwater Management Certification under this Ordinance.
15-31. Letters of Permission. The Administrator, or the Director in Non-Waiver Communities, shall have the option of issuing a “Letter of Permission” in lieu of a Stormwater Management Certification. A Letter of Permission may be issued for Developments that can be determined, based on review of the Applicants proposed plans, available documents, site inspection and judgment, to be limited in scope and complexity and fit the definition, for “Minor Development”. The Applicant may propose that certain submittal requirements be waived for those Developments approved for processing as a Letter of Permission, provided that the request is in writing and in advance of the submittal, and the request is approved in writing by the Administrator or the Director in a Non-Waiver Community. The Applicant, or if applicable their design professionals, must affirm that all calculations are in accordance with standard engineering practice and have been checked for accuracy of calculation and are in compliance with the requirements of this Ordinance. The Applicant shall remain responsible for any errors in calculation or application of engineering methodology.
15-31.A The following are the potential modifications to submittal requirements in the form of “waiving submittal” that may be considered.
15-31.A.1 Supporting calculations for simple soil erosion and sediment control plans, if the Development is not subject to NPDES permitting;
15-31.A.2 Routine backup calculations such as time of concentration, runoff curve number, and storm sewer design calculations;
15-31.A.3 Copies of maps such as soils maps.
15-31.A.4 Other supporting calculations when the results used in the design appear to the Administrator to be within the norms of engineering practice.
15-31.B The following are not eligible to be “waived for submittal”
15-31.B.1 Construction plans complete with all details, including soil erosion and sediment control plan must be submitted by the Applicant.
15-31.B.2 Development Securities in the amounts and forms defined in this Ordinance, record exhibits and maintenance easements may be reduced or waived if adequate other securities are required under other building permit requirements such that the Administrator or Director in a Non-Waiver Community is reasonably assured that the intent of those provisions in this Ordinance is carried out.
15-31.C Decisions made on behalf of the Community by the Administrator or Director with regard to Letters of Permission applicability and submittal requirements are by permission to the Applicant.
15-31.D The Letter of Permission will serve in all respects as the Stormwater Management Certification, with the same duration, and may be combined with a General Certification for the parts of the Development to which a General Certification might be applicable.
15-31.E A Letter of Permission cannot be used to substantively change the technical standards of this Ordinance.
15-32. General Certifications. The Director, or the Administrator in a Waiver Community, may issue General Certifications which when adopted by the Stormwater Committee, County Board, and Oversight Committee and when found applicable to the particular circumstances of a Development, will serve as the Stormwater Management Certification for the Development activity, or a portion of the Development activity. General Certifications may provide clarification or interpretation of technical requirements and are intended to address common and generally low impact Developments, reducing submittal requirements, design costs and the public burden to apply for Certification and review such Development cases. The Applicant may be required to make a submittal and pay review fees, as described in the General Certification or in the Community’s fee schedule. As long as the Applicant abides by the Special Conditions as described in the General Certification, then the Development will be considered as having obtained a Stormwater Management Certification.
15-32.A Types of Developments for General Certification drafts will be recommended by the MEG, who may refer them to a committee of the MEG or County staff. The Director will present the General
Certification to the Stormwater Committee for those General Certifications with countywide applicability. When initiated by an Administrator, the Administrator shall obtain a recommendation from the Director, who will also refer it to the MEG for a recommendation. Any General Certification may be used by any Community. A General Certification must be adopted by the Community for use in that Community or by the County Board for applicability Countywide.
15-32.B General Certifications are authorized for one year and shall be automatically renewed annually unless action is taken to change the Certification within 60 days of expiration. An Applicant who relied on a General Certification shall have one year from the date of reauthorization to complete the Development under the terms of the General Certification as it read at the time the General Certification was issued.
15-33. Datum. All topographic maps or exhibits, and Record Drawings associated to a project shall be tied to the North American Vertical Datum of 1988 (NAVD88) of the National Spatial Reference System (NSRS) as maintained by the United States National Geodetic Survey (NGS). A minimum of two vertical geodetic control points shall be established on or adjacent to the project to tie the elevations of each project to NAVD88. The methods used by an Illinois Professional Land Surveyor to establish NAVD 88 elevations shall achieve a national NSRS vertical network accuracy of 0.15 of a U.S. Survey foot (5 centimeters) or better to be in compliance with FEMA requirements, as specified in the FEMA document “Guidelines and Specifications for Flood Hazard Mapping Partners” dated April 2003. The surveyor shall use one of the following two methods to achieve vertical network accuracy as well as to provide documentation to substantiate the vertical network accuracy.
15-33.A Establish vertical geodetic control at the site using a combination of GNSS measured ellipsoid heights and calculated orthometric heights using the most current available version of a reputable Geoid Model. Global Navigation Satellite System (GNSS) derived ellipsoid heights shall be determined by processing GPS field measurements through the NGS GPS Online Positioning System – Rapid Static service (OPUS-RS). The surveyor shall provide to the County a copy of the OPUS-RS report.
15-33.B Establish vertical geodetic control at the site by differential leveling surveying using NGS specifications for Third-Order vertical surveys. All vertical leveling must be measured relative to at least two NSRS vertical geodetic control monuments of Second-Order or better accuracy. The surveyor shall provide to the County a list of the two or more NGS Second-Order vertical geodetic control monuments used during the leveling survey and a copy of the leveling notes.
15-34. Requirements for Applicants to use Professional Engineers and Surveyors. Calculations for the design of Stormwater Facilities, determination of the Regulatory Flood Plain, or calculations of the impact of the Development shall be prepared, signed and sealed by a Professional Engineer, or Professional Land Surveyor when they are legally entitled to sign. Structures
which are subject to a differential water pressure head of greater than three feet shall be designed under the supervision of a Licensed Structural Engineer, who shall sign and seal the design plans and calculations. Topographic exhibits and Record Drawings may alternatively be signed and sealed by a Professional Land Surveyor.
15-35. Requirements for Applicants to use Environmental Scientist. When required, all determinations regarding the absence or presence of Wetlands on the Development Site or within one hundred (100) feet from the Development Site shall be performed by an Environmental Scientist (Section 15-85.B), unless the Director or Administrator concludes and documents otherwise in accordance with Section 15-85.A.
15-36. Professional Engineer statement with application. Unless waived by the Community or by General Certification, a Professional Engineer under the employment of the Applicant shall provide a statement rendering an opinion that the Development meets the minimum criteria for stormwater management in accordance with this Ordinance, or the applicable Waiver Community Ordinance.
15-37. Other Agency Approvals. No work may begin on a site in those areas under the jurisdiction of any other stormwater authority until the authority’s permits or approvals have been obtained. Failure to obtain a permit from other required stormwater related jurisdictions will invalidate an issued Stormwater Management Certification. When the Development qualifies for and meets the special conditions of an IDNR-OWR General, Regional or Statewide permit, then no special approval correspondence from IDNR-OWR will be required.
15-38. Community Developments. A Community must obtain a permit from IDNR- OWR, or their designee, prior to issuance of a Stormwater Management Certification for any Community Development that falls under the jurisdiction of IDNR-OWR, unless the Development qualifies for and meets the special conditions of an IDNR-OWR General, Regional or Statewide permit, then no special approval correspondence from IDNR-OWR will be required.
15-39. IDNR-OWR reserved review. For Development within the Regulatory Floodway, the following calculations or analyses shall be submitted to and approved by IDNR-OWR or its designee prior to issuance of a Stormwater Management Certification:
15-39.A Flood damage analysis for the replacement or modification of existing bridges or culverts;
15-39.B Hydraulic analysis of new, modified or replacement bridges or culverts;
15-39.C Analyses of alternate transition sections from those required in Section 15-82.E. of this Ordinance; and
15-39.D Analyses of hydrologically and hydraulically equivalent storage.
15-39.E Any embankment or Structure meeting IDNR-OWR’s definition of a Dam, including areas outside the Regulatory Floodway.
15-40. Certification Application Requirements and Submittals. The specific applicable technical requirements and the extent of documentation required to be submitted may vary depending on existing conditions of the Development Site. The Applicant shall combine the separate “submittals” referenced in each article into a single application package of materials. Unless superseded by application under either a General Certification or a Letter of Permission, or the Director or Administrator specifically allows a modification of the submittal requirements in writing, the following shall guide the determination that an application for Stormwater Management Certification is complete.
15-40.A Stormwater Submittal. All Developments requiring a Stormwater Management Certification are required to submit the information required for Minimum Submittal (Section 15-47.A). The requirement for Record Drawings (Section 15-47.B) applies to all Developments that construct Stormwater Facilities, or include wetland, Buffer or Flood Plain onsite. Unless the Development fits the definition of Minor Development, the plans and calculations listed in Section 15-47.D will also be required (as relevant to the specific Development).
15-40.B Maintenance Plan. When the Development includes construction of a Site Runoff Storage Facility or Post Construction Best Management Practices, a maintenance plan specifying tasks and frequency shall be submitted.
15-40.C The provisions of Section 15-55 shall apply to all Developments except:
15-40.C.1 Developments classified as Minor Developments; or
15-40.C.2 Developments which do not include site stormwater storage facilities and which do not include any Best Management Practices with a design drainage area greater than 1-acre.
15-40.D Performance Security. Performance Security in accordance with Section 15-54 may be combined into a single instrument and is required as follows.
15-40.D.1 Development Security in accordance with Section 15-
54.B. is required for all Developments which are not Minor Developments, and which include construction of a Stormwater Facility (Article IX), or more than 200 feet of Storm Sewer, or a Post Construction Best Management Practice (Article VIII) designed to serve more than 1-acre of drainage area.
15-40.D.2 Erosion and Sediment Control Security in accordance with Section 15-54.C is required for any Development disturbing more than 1-acre, or which disturbs the bed and banks of a Channel draining more than 100-acres, or when an Erosion and Sediment Control Plan is required because of impact to Wetlands or Buffers or Flood Plain.
15-40.D.3 A Natural Area, Wetland and Buffer Mitigation Area Security shall be posted per Section 15-54.D. Whenever a natural area is being restored or a Wetland or Buffer is impacted and mitigated, unless Mitigation is provided by fee-in-lieu.
15-40.E Soil Erosion and Sediment Control. All Developments must provide both temporary and permanent Soil Erosion and Sediment Control; however, plans for these measures must be submitted for review only where the Development is required to obtain a Stormwater Management Certification (Section 15-30). Developments required to make application may obtain a Letter of Permission (Section 15- 31), even if it is not a Minor Development, as long as no other aspect of the Development requires review under Articles VIII, IX, X or XI. All other applications shall include the following based on area of land disturbance of the proposed Development:
15-40.E.1 If the land disturbance is less 1 acre and does not disturb the bed and banks of a Channel draining more than 100- acres, and the Development does not involve impact to Buffer or wetland or Flood Plain, and is not part of a larger common plan, then the submittal shall be per Section 15-50.B.
15-40.E.2 If the land disturbance is one 1-acre or greater or disturbs the bed or banks of a Channel draining more than 100-acres, or the Development includes impact to Buffers or Wetlands or Flood Plain, then the requirements of Sections 15-50.C and 15-50.D shall apply.
15-40.F Post Construction Best Management Practices. When the impervious coverage of the Development Site is increased by 2,500 square feet or more compared to the Pre-Development Site then PCBMPs designed in accordance with Section 15-63 through Section 15-70 are required and submittals in accordance with Section 15-49 are required with the Application, unless one of the exceptions or exclusions listed in Section 15-63 applies.
15-40.G Flood Plains and Floodways. All developments shall check the requirements of Section 15-80 to determine if Flood Plain exists on a Development Site. Chart 3 is included in Appendix C as a guide. If Flood Plain does exist on the Development Site, a BFE shall be established as outlined in Section 15-80.D and shall be drawn on the site topographic map. If the datum for the BFE determination is different from the site topographic map datum, the appropriate conversion factor shall be used. The DuPage County developed conversion factors from NGVD29 to NAVD88 per Watershed, shall be used when appropriate. If the proposed work is outside of the BFE, there shall be no additional requirements from Article X that need to be met. Applicants shall determine if Floodway exists following Section 15-80.F. For Developments that involve work within the Flood Plain or, where there is Floodway within the disturbed area, the Flood Plain and Floodway shall be delineated on the site plan.
15-40.G.1 For Developments within the Flood Plain, document that Section 15-81 requirements are being met with a narrative and appropriate calculations, modeling, cross-sections and plans.
15-40.G.2 For Developments within the Floodway, document that Section 15-82 requirements are being met with a narrative and appropriate calculations, modeling, cross-sections and plans per Section 15-51.
15-40.H Wetlands. A flowchart is included in Appendix C as a guide. Stormwater Management Certifications are required for Developments where the area being disturbed, or developed, is within 100 feet of a wetland located either on-site or off-site. The application shall include the following.
15-40.H.1 A wetland delineation and report will be required unless the wetland is determined to be greater than 100 feet away from the Development’s limit of disturbance, and Section 15-17.A.1.a is applied by the Administrator in a Partial Waiver Community, or with the concurrence of the Administrator in a Complete Waiver Community, or the Director in a Non-Waiver Community.
15-40.H.2 If the Development’s proposed limit of disturbance is within 100 feet of a wetland, then,
15-40.H.2.a. A wetland delineation and report will be required (Section 15-85), unless the wetland has clearly defined boundaries and there are no proposed wetland or Buffer Direct Impacts or indirect wetland hydrologic impacts that exceed the thresholds found in Section 15-87.
15-40.H.2.b. If there are Direct Impacts to the wetland, then the wetland submittal in accordance with Section 15-48 will be required.
15-40.H.2.c. If the Development will cause an indirect impact to a wetland an indirect impact analysis shall be included in the Wetland Submittal.
15-40.H.2.d. If the Development has a direct or indirect Permanent Wetland Impact a hydrologic analysis of the Mitigation area (Section 15-88.L) and a maintenance and monitoring plan (Section 15-88.M) are required to be submitted, unless Fee in Lieu of Mitigation is provided.
15-40.I Buffers. See also the flowchart in Appendix C. Direct Impacts to Buffers (Section 15-92) will require a Buffer Submittal in accordance with Section 15-48.
15-41. Special Cases of Development. Special Cases of Development shall have differing submittal or, technical standards than other Developments, as summarized in Table 1.
FLOOD PLAIN/ FLOODWAY (Note
POST CONSTRUCTION BEST MANAGEMENT PRACTICES
SITE RUNOFF STORAGE
OR 15-63.A.1 (NEW)
POSSIBLE SITE RUNOFF STORAGE
(SPECIAL) 15-72.A.4 15-72.B
BRIDGE AND CULVERT MODIFICATION
NAUTRAL AREA RESTORATION
WETLAND MITIGATION SITE
WETLAND MITIGATION BANK
TRAIL DEVELOPMENT, BIKEWAY,
15-63.A.5 (MEETING CONDITIONS)
EXEMPT 15-72.C.5 (MEETING
OPEN SPACE DEVELOPMENT
=2,500 S.F. NET NEW IMPERVIOUS
ONLY SITE RUNOFF STORAGE (SPECIAL)
WATER AND SEWER IMPROVEMENT
Table 1 Note: Referenced Ordinance Sections apply to the Special Cases of Development.
TABLE 1: SPECIAL CASES OF DEVELOPMENT
15-42. Fees for Certification and Authorization by the County and other fees.
15-42.A A review and inspection fee schedule for Stormwater Management Certifications in Non-Waiver Communities, and for Authorization reviews performed by the County on behalf of Waiver
Communities, is attached to this Ordinance as Schedule A and by this reference incorporated into this Ordinance.
15-42.B All Certification review and inspection fees for Development in Non-Waiver Communities, and in those areas of review undertaken by the County in Waiver Communities, shall be payable to the Department.
15-42.C Waiver Communities may set Certification review and inspection fees or set up escrow accounts for payment of review costs for Developments within their jurisdictions.
15-42.D All stormwater management review fees shall be paid at the time directed by the Administrator or Director.
15-42.E Any fee-in-lieu that is part of the conditions for issuance must be paid prior to issuance of the Certification.
15-43. Release of Performance Security and Easements. The Record Drawings requirements of Sections 15-47.B and the applicable requirements of 15-55 will also be required to be satisfied prior to the release of the remaining development securities in Section 15-54.
15-44. Duration and Revision to Certifications and Authorizations. Certifications expire December 31st of the third year from the date of Certification or Authorization, whichever is sooner.
15-44.A If the certified activity has been started but is not completed by the expiration date of the Certification, and the Certification holder intends to pursue the certified or authorized activity, then the Certification holder must submit a written request that the expiration date be extended. Upon receipt of such request, the Director or the Administrator may extend the expiration date in maximum increments of three years for Certified or authorized activities, provided the activity is in compliance with the then current requirements of this Ordinance or the applicable Waiver Community Ordinance. Expiration dates for Certified or authorized activities within Wetlands and Buffers may be extended provided that an updated delineation shows no significant change in wetland boundary or classification.
15-44.B If, after Certification issuance, the Certification holder decides to revise the approved plans, the Certification holder shall submit revised plans to the Director or the Administrator, along with written request for approval by the expiration date. If the Director or the Administrator determines that the revised plans are in compliance with the then current requirements of this Ordinance or the applicable Waiver Community Ordinance, an approval of the revised plans will be issued.
15-44.C No activity by the Applicant in the form of a resubmittal or follow- through on outstanding issues required for Certification in the 12 month period following the date of the last correspondence from the Director, or Administrator, pertaining to the Application, will be cause for considering the application withdrawn.
15-47. Stormwater Submittals
15-47.A Minimum Submittal. Unless one of the following is specifically waived with documentation by the Director or the Administrator in a Waiver Community, or the Development is eligible for Certification by a General Certification or Letter of Permission, a minimum Stormwater Submittal shall be required for all Developments requiring Certification. The following constitutes a minimum Stormwater Submittal, unless modified by Waiver Community Ordinance:
15-47.A.1 The name and legal address of the Applicant and of the owner of the land; and
15-47.A.2 The common address and legal description of the site where the Development will take place; and
15-47.A.3 Affidavits signed by the land owner and the Developer attesting to their understanding of the requirements of this Ordinance or the applicable Waiver Community Ordinance and their intent to comply therewith, including the submittal of a record drawing in accordance with Section 15-47.B; and
15-47.A.4 A listing of all other required stormwater related permits, a brief description of how the other permits apply to the Development, and when requested by the Director or the Administrator, complete copies of the applications for the permits; and
15-47.A.5 A statement of opinion by a qualified professional(s) either acknowledging or denying the presence of Flood Plain in accordance with Section 15-80, Wetlands in accordance with Section 15-85, and Buffers in accordance with Section 15-92; and
15-47.A.6 A standard engineering scaled drawing depicting any proposed major Stormwater Facilities on a topographic map depicting any offsite upstream drainage area and the characteristics of the downstream facilities receiving discharge from the Development.
15-47.A.7 An exhibit at standard engineering scale is also required that is used as the basis to determine the extent of existing Impervious Area, proposed developed Impervious Area, and extent of area to be disturbed in the construction of the Development.
15-47.A.8 A statement from the Applicant acknowledging that all stormwater submittals shall be made available for inspection and copying by the County, notwithstanding any exemption from inspection and copying for such materials under the Illinois Freedom of Information Act, upon the written request of either: i) the Applicant ii) any subsequent owner of the subject property; or iii) any governmental unit having planning or drainage jurisdiction within 1 and 1/2 mile of the subject property.
15-47.B Upon completion of the Stormwater Facilities, a record drawing signed and sealed by either a Professional Engineer or a Professional Land Surveyor depicting the as-constructed size, rim and inverts elevations of pipes, stormwater Structures and culverts, and contours and Flood storage volumes of all required basins of the Major Stormwater Systems and Minor Stormwater Systems.
15-47.C An informational note acknowledging the presence of on-site Wetlands, Buffers, Flood Plains, and PCBMPs with drainage areas 1 acre or greater, shall be recorded against the title to alert all future owners and shall reference the Stormwater Management Certification number.
15-47.D Documentation supporting Certification compliance. The following items will be submitted to demonstrate and support that the application for Certification is in compliance with this Ordinance. The Administrator or Director may approve, in writing, an application without some or all of these items based on the extent and complexity of the Development. All plans and drawings shall be at standard engineering scale.
15-47.D.1 A scaled plan or plans illustrating the major and minor conveyance system, including:
15-47.D.2 Size, type, length and inverts of conveyance Structures including drainage pipes, culverts, manholes, catch basins, inlets, and drain tiles.
15-47.D.3 A scaled exhibit illustrating the Impervious Area of the site prior to the Certification along with a calculation of the percentage of the site that is impervious.
15-47.D.4 A scaled exhibit illustrating the proposed impervious surfaces of the Development.
15-47.D.5 Calculations of the percentage of impervious surfaces after complete construction of the proposed Development.
15-47.D.6 Scaled plans illustrating the location of and details for site runoff storage.
15-47.D.7 Calculations that establish the required site runoff storage volume along with calculations confirming that the proposed plan achieves either the site runoff storage or the modified site runoff storage.
15-47.D.8 When site runoff storage special is required, calculations that demonstrate the specified post Development discharges have not exceeded the predevelopment values.
15-48. Wetland and Buffer Impact Submittals.
15-48.A The submittal shall include all the following information unless the Director or Administrator concludes otherwise in accordance with Sections 15-17.A.1.a or 15-85.A.
15-48.A.1 A complete wetland delineation report prepared in accordance with the Federal Methodology. The report shall also contain the following.
15-48.A.1.a. Completed USACE wetland delineation data forms.
15-48.A.1.b. Aerial photograph, or other exhibit, clearly showing wetland boundaries, location of wetland delineation data points, and offsite Wetlands within 100’ of the property.
15-48.A.1.c. A narrative describing the physical characteristics and size of each onsite wetland and Buffer including a floristic inventory list, calculated mean C and Floristic Quality Index (FQI) calculated for each onsite wetland area.
15-48.A.1.d. Representative photos of each wetland and its associated Buffer.
15-48.A.1.e. Copies of the below listed information shall be provided:
15-48.A.1.e.1. Floristic Inventory List.
15-48.A.1.e.2. NRCS DuPage County Soil Survey map with legend identifying any mapped hydric soils.
15-48.A.1.e.3. IDNR Threatened and Endangered Species consultation (EcoCAT).
15-48.A.1.e.4. National Wetland Inventory Map.
15-48.A.1.e.5. DuPage County Wetland Inventory Map.
15-48.A.1.e.6. DuPage County Regulatory Flood Plain Map and Flood Insurance Rate Map.
15-48.A.1.e.7. Site location map with approximate scale.
15-48.A.2 For critical Wetland Impacts, complete an Alternatives Analysis in accordance with Section 15-86.B.
15-48.A.3 For impacts to Regulatory Wetlands/Waters of DuPage greater than 0.1 acre total surface area, or Corps of Engineers jurisdictional waters or wetland, complete an alternative analysis in accordance with Section 15-86.C.
15-48.B USACE Jurisdictional Wetland. If a USACE jurisdictional wetland will be impacted, a copy of a Letter of No Objection, General, Regional, or Individual Permit shall be provided prior to issuance of the Stormwater Management Certification, unless the Director or Administrator concludes otherwise. In which case, the Certification can be conditioned to state that such work may not commence within or adjacent to the waters of the United States or wetland until receipt of the necessary USACE authorization.
15-48.C The following support documentation is required to be submitted. The Administrator or Director may waive the requirement to provide some or all of the following support documentation when considering the complexity and extent of the proposed Development and its impact: 15-48.C.1 Wetland delineation plan view that includes a depiction of the Buffer limits (Section 15-92).
15-48.C.2 Statement indicating the date of the wetland boundary verification and OHWM verification.
15-48.C.3 Indirect impact determination. When required, documentation including subarea Watershed map and hydrologic calculations with a table summarizing results in accordance with the analysis in Section 15-87 is required.
15-48.C.4 Development narrative shall include the following applicable items:
15-48.C.4.a. Description of the functions of the impacted wetland or Buffer, and how the impacts will be mitigated.
15-48.C.4.b. Historic aerials, if available, to document the previous site conditions or the extent of farmed wetland.
15-48.C.4.c. Description of Mitigation method, location, and ratios.
15-48.C.4.d. Description of Mitigation area and plan objectives.
15-48.C.4.e. Description of management practices. The document shall include clarification that prescribed burns and herbicide applications must be performed by trained/licensed personnel under the proper permits.
15-48.C.4.f. Performance Standards. 15-48.C.4.g. Reporting requirements.
15-48.C.4.h. Hydrology monitoring methodology and goals.
15-48.C.4.i. Implementation schedule.
15-48.C.4.j. Native species list with quantities, size of stock, seeding rate and/or plug spacing.
15-48.C.4.k. Planting specifications and soil handling.
15-48.C.4.l. Cost estimate to include installation, management, monitoring, and reporting as anticipated to meet Performance Standards.
15-48.C.5 Plan view drawings and details, where applicable:
15-48.C.5.a. Existing and proposed topography.
15-48.C.5.b. Delineated wetland and Waters of DuPage OHWM boundary to a sub meter accuracy or better.
15-48.C.5.c. Buffer boundary.
15-48.C.5.d. Location of impacts to wetland and Buffer.
15-48.C.5.e. A table shall be provided on the plans listing the total acreage of the existing wetland and Buffer areas, and the proposed impact and Mitigation areas. These calculated areas should also be graphically highlighted.
15-48.C.6 Wetland and Buffer Mitigation plan, if applicable, shall contain the following information:
15-48.C.6.a. Delineate and label planting and seeding zones.
15-48.C.6.b. Delineate and label Mitigation and enhancement zones.
15-48.C.6.c. Existing and proposed topography.
15-48.C.6.d. Planting methodology and soil handling.
15-48.C.6.e. Proposed wetland and Buffer boundaries.
15-48.C.6.f. Native species list including size of stock, quantity, seed rate, and spacing of plugs.
15-48.C.6.g. Woody planting locations, if any.
15-48.C.6.h. Signage or physical barrier locations.
15-48.C.6.i. Monitoring well locations, if installed.
15-48.C.6.j. Permanent transect locations and photo- documentation points for monitoring, if required.
15-48.C.6.k. Maintenance and monitoring plan with Performance Standards.
15-49. Post Construction Best Management Practice Submittal. The Post Construction Best Management Practice (PCBMP) submittal shall include:
15-49.A A discussion documenting compliance with the requirements of Article VIII.
15-49.B A listing and discussion of all PCBMPs to be used.
15-49.C Supporting calculations documenting compliance with the volume reduction BMP requirements.
15-49.D For manufactured PCBMPs, the manufacturer documentation to support pollutant removal rates shall be supplied.
15-49.E A BMP specific planting/seeding plan for all areas to be vegetated which shall include:
15-49.E.1 Identified locations for all plantings (e.g., lawn, upland prairie, wet prairie, etc.), seeding and planting specifications and methodology.
15-49.E.2 A schedule for installation.
15-49.E.3 Proposed maintenance and monitoring provisions.
15-49.E.4 An opinion of probable cost to construct the BMPs.
15-50. Soil Erosion and Sediment Control Submittal Requirements.
15-50.A Developments that only require approval of the soil erosion and sediment control provisions of this Ordinance and do not require approval for any other aspect of this Ordinance shall be reviewed and processed as a Letter of Permission (LOP). To be eligible for a LOP, in addition to the requirements of this Ordinance, the Applicant must certify that he is aware of the design requirements of the IEPA NPDES ILR10 permit and certify that the plan meets those requirements.
15-50.B For Developments with less than one acre of land disturbance that are not part of a larger common plan, a qualified designer shall certify that the Development meets the soil erosion and sediment control design criteria found in Article VII have been met. However, formal submittal of the information under Section 15-50.D. is unnecessary unless the Director or Administrator requests demonstration of compliance with these provisions.
15-50.C For Developments that disturb one or more acres of land area, or will disturb less than one acre of land, but are part of a larger common plan that will ultimately disturb one or more acre land area, the Applicant shall prepare and provide a copy of a SWPPP in accordance with the requirements of Illinois Environmental Protection Agency General NPDES Permit No. ILR 10, Part IV.D.1.a-f (Contents of Plan), Part IV.D.2.a-d (Controls), Part IV.D.3 (Maintenance) and Part IV.D.4.a- f (Inspections). The plan prepared for the SWPPP may be submitted as the SESC Plan for the Development.
15-50.D If the SESC plan does not appear adequate to comply with the design requirements of Article VII, in the opinion of the Administrator or Director, then the Administrator or Director may require submittal of any or all of the following to demonstrate the plan’s compliance. Site maps which indicate:
15-50.D.1 One foot contours with delineated sub-basins.
15-50.D.2 Approximate slopes anticipated before and after major grading activities.
15-50.D.3 Locations where vehicles enter or exit the site and, controls to prevent offsite sediment tracking areas, and concrete washout controls and procedures, limits of soil disturbance, and the location of major structural and nonstructural controls identified in the plan.
15-50.D.4 The location of areas where stabilization practices are expected to occur.
15-50.D.5 Surface waters (including Wetlands), and locations where stormwater is discharged to a surface water.
15-50.D.6 Developments that will extend through winter shall provide a description of winter specific soil erosion and sediment control measures to be implemented.
15-50.D.7 A description of the nature of the construction activity or demolition work.
15-50.D.8 A description of the intended sequence of major activities which disturb soils for major portions of the site (e.g., clearing, grubbing, excavation, grading) and construction stabilization schedule.
15-50.D.9 An estimate of the total area of the site, and the total area of the site that is expected to be disturbed by excavation, grading, or other activities.
15-51. Submittal Requirements for Development in the Regulatory Flood Plain.
15-51.A Developments located in the Regulatory Flood Plain shall, at a minimum, provide the following:
15-51.A.1 A copy of the effective FIRM, RFM, and DFIRM (if available) drawn to scale and showing the limits of the Regulatory Flood Plain, Regulatory Floodway, and the boundaries of the Development Site. If available, a FIRMette should be made for the Development Site. A FIRMette is a full- scale section of a FEMA FIRM) that is created through FEMA’s website.
15-51.A.2 Engineering calculations and designs that demonstrate the proposed Development meets the Flood Plain requirements of this Ordinance. All calculations and designs shall be prepared, signed, and sealed by a Professional Engineer.
15-51.A.3 A topographical map of the Development Site, showing the boundaries of the Development Site and the limits of the existing and proposed conditions Zone A Regulatory Flood Plain and Regulatory Floodway.
15-51.A.4 The Applicant shall obtain and provide copies of all required local, state, and federal permits prior to approval for a Stormwater Management Certification.
15-54. Performance Security
15-54.A General Security Requirements.
15-54.A.1 As security to the County or the Waiver Community for the performance by the Developer of the Developer's obligations to complete the construction of any Stormwater Facilities required by the Stormwater Management Certification, to ensure that such Stormwater Facilities function as designed after construction, to pay all costs, fees, and charges due from the Developer pursuant to this Ordinance or the applicable Waiver Community Ordinance, and to otherwise faithfully perform the Developer's undertakings pursuant to this Ordinance or the applicable Waiver Community Ordinance, the Developer shall, prior to issuance of a Stormwater Management Certification and in accordance with Section 15-40.D, post performance security and grant easements as hereafter described.
15-54.A.2 The Developer shall bear the full cost of securing and maintaining the securities required by this Article VI in accordance with Section 15-40.D.
15-54.A.3 Performance Security required by this Article VI may be posted in the form of one or more surety instruments as the Director, or Administrator, deems appropriate for the proposed Development.
15-54.A.4 Public bodies shall not be required to post Performance Security under this Article VI for Development activities which involve construction, improvement, relocation, or demolition work paid for in whole or in part with public funds.
15-54.A.5 The Developer shall grant the County, or Waiver Community, a temporary easement which authorizes, but does not obligate, the County, or Waiver Community, to access the Development Site to perform or complete any act or work the Developer is required to do by the Stormwater Management Certification which may include; (i) the construction of any required Stormwater Facilities; (ii) restoration and/or Mitigation of natural areas, Wetlands and Buffers; (iii) installation and Maintenance of soil erosion control; (iv) planting or removal of vegetation; and (v) any other maintenance or monitoring. The term for such easements shall be of sufficient duration as necessary to allow the County, or Waiver Community, to perform and satisfactorily complete any activity or work for which the Developer/certificate holder has posted security under this Article VI.
15-54.B Development Security
15-54.B.1 A development security shall be posted and shall include:
15-54.B.1.a. A schedule, agreed upon by the Developer and the Director or the Administrator, for the completion of the construction of any Stormwater Facilities required by the Certification; and
15-54.B.1.b. An irrevocable letter of credit, or such other adequate security as the Director or the Administrator may approve, in an amount equal to not less than one hundred ten percent (110%) of the estimated probable cost to complete the construction of any Stormwater Facilities required by the Stormwater Management Certification, which estimated probable cost shall be approved by the Director or the Administrator; and
15-54.B.1.c. A statement signed by the Applicant granting the Director or the Administrator the right to draw on the security and the right to enter the Development Site to complete required work in the event that work is not completed according to the work schedule; and
15-54.B.1.d. A statement signed by the Applicant that the Applicant shall indemnify the Community and the Department for any additional costs incurred attributable to concurrent activities of or conflicts between the Applicant's contractor and the Community's or Department's remedial contractor at the site.
15-54.B.2 The security required by this Section 15-54.B shall be maintained and renewed by the Applicant, and shall be held in escrow by the Director or the Administrator until the conditions set forth in this Section 15-54.B.2 and Section 15-55 or other applicable provision are satisfied.
15-54.B.3 After approval of Record Drawings and final inspection of any constructed Stormwater Facilities by the Director or the Administrator, not more than ninety percent (90%) of the security provided for in this Section 15-54.B or other applicable provision may be released. A minimum of ten percent (10%) of the security shall be retained after completion of construction of such Stormwater Facilities, for a period of time not less than one (1) year, to ensure the satisfactory performance of such Stormwater Facilities. The remaining Development Security shall be released after the Director or the Administrator verifies, by an inspection performed not sooner than one-year following the final construction inspection, that such Stormwater Facilities function as provided for in the Certification.
15-54.C Soil Erosion and Sediment Control Security
15-54.C.1 If a soil erosion and sediment control security is required pursuant to Section 15-40.D.2 of this Ordinance, such a security shall include:
15-54.C.1.a. An irrevocable letter of credit, or such other adequate security as the Director or the Administrator shall approve, in an amount equal to not less than one hundred ten percent (110%) of the estimated probable cost to install and maintain the erosion and sediment control measures, which estimated probable cost shall be approved by the Director or the Administrator; and
15-54.C.1.b. A statement signed by the Applicant granting the Director or the Administrator, as applicable, the right to draw on the security and the right to enter the Development Site to complete erosion and sediment control measures in the event that such measures are not installed and maintained according to the established schedule.
15-54.C.2 The security required by this Section 15-54.C shall be maintained and renewed by the Applicant, and shall be held in escrow by the Director or the Administrator, as applicable, until the conditions set forth in Sections 15-54.C.3 and 15-55 are satisfied.
15-54.C.3 After establishment of vegetation, removal of all sediment from Stormwater Facilities unless designed otherwise, and final inspection and approval by the Director or the Administrator, as applicable, one hundred percent (100%) of the erosion and sediment control security shall be released.
15-54.D Natural Area Restoration, Wetland and Buffer Mitigation Area Security
15-54.D.1 Natural area restoration or wetland and Buffer Mitigation area security, in accordance with Section 15-40.D.3 shall be posted and shall include:
15-54.D.1.a. A schedule, agreed upon by the Developer and the Director or the Administrator, for the completion of a natural area restoration Development or completion of wetland or Buffer Mitigation Development; and
15-54.D.1.b. An irrevocable letter of credit, or other such adequate security as the Director or the Administrator may approve, in an amount equal to, not less than, one hundred ten percent (110%) of the estimated probable cost to plant, maintain and monitor all vegetated areas and/or complete the restoration or Mitigation Development for the agreed upon maintenance and monitoring period as required by the Certification. The estimated probable cost shall be approved by the Director or the Administrator; and
15-54.D.1.c. A statement signed by the Applicant granting the Director or the Administrator the right to draw on the security and the right to enter the Development Site to complete the work in the event that work is not completed according to the work schedule; and
15-54.D.1.d. A statement signed by the Applicant that the Applicant shall indemnify the Community and the Department for any additional costs incurred attributable to concurrent activities of, or conflicts between, the Applicant's contractor and the Community's or Department's remedial contractor at the site.
15-54.D.2 The security required by Section 15-54.D shall be maintained and renewed by the Applicant, and shall be held in escrow by the Director or the Administrator until the conditions set forth in Section15-54.D.4 and Section 15-55, or other applicable provision are satisfied.
15-54.D.3 The natural area restoration or wetland and Buffer Mitigation areas security may be reduced at the discretion of the Director or Administrator as conditions are met, but must not be less than one hundred ten percent (110%) of the estimated probable cost to continue to meet all conditions or other applicable provisions
15-54.D.4 After approval by the Director or the Administrator, not more than ninety percent (90%) of the security provided for in this Section 15-54.D, or other applicable provision may be released. A minimum of ten percent (10%) of the security shall be retained for the length of the required monitoring period, which shall not be less than one (1) year from the completion of the initial restoration or Mitigation activities, to ensure the satisfactory establishment of any vegetated areas required by the Certification.
15-54.E Letters of Credit
15-54.E.1 Letters of credit posted pursuant to Section 15-54.B, 15- 54.C, and 15-54.D of this Ordinance shall be in a form satisfactory to the Director or the Administrator, as applicable.
15-54.E.2 Each letter of credit shall be from a lending institution: (a) acceptable to the Director or the Administrator, as applicable; (b) having capital resources of at least ten million dollars ($10,000,000), or such other amount acceptable to the Director or the Administrator; (c) with an office in the Chicago Metropolitan Area; and, (d) insured by the Federal Deposit Insurance Corporation.
15-54.E.3 Each letter of credit shall, at a minimum, provide that:
15-54.E.3.a. It shall not be canceled without the prior written consent of the Director or the Administrator; and
15-54.E.3.b. It shall not require the consent of the Developer prior to any draw on it by the Director or the Administrator; and
15-54.E.3.c. If at any time it will expire within 45 or any lesser number of days, and if it has not been renewed, and if any applicable obligation of the Developer for which its security remains uncompleted or is unsatisfactory, then the Director or the Administrator may, without notice and without being required to take any further action of any nature whatsoever, call and draw down the letter of credit and thereafter either hold all proceeds as security for the satisfactory completion of all such obligations or employ the proceeds to complete all such obligations and reimburse the County or the Waiver Community for any and all costs and expenses, including legal fees and administrative costs, incurred by the County or the Waiver Community, as the Director or the Administrator shall determine.
15-54.E.4 If at any time the Director or the Administrator determines that the funds remaining in the letter of credit are not, or may not be, sufficient to pay in full the remaining unpaid cost of all Stormwater Facility construction or erosion and sediment control measures, then, within ten (10) days following a demand by the Director or the Administrator, the Developer shall increase the amount of the letter of credit to an amount determined by the Director or the Administrator to be sufficient to pay such unpaid costs. Failure to so increase the amount of the security shall be grounds for the Director or the Administrator to draw down the entire remaining balance of the letter of credit.
15-54.E.5 If at any time the Director or the Administrator determines that the bank issuing the letter of credit is without capital resources of at least ten million dollars ($10,000,000), is unable to meet any federal or state requirement for reserves, is insolvent, is in danger of becoming any of the foregoing, or is otherwise in danger of being unable to honor such letter of credit at any time during its term, or if the Director or the Administrator otherwise reasonably deems the bank to be insecure, then the Director or the Administrator shall have the right to demand that the Developer provide a replacement letter of credit from a bank satisfactory to the Director or the Administrator. Such replacement letter of credit shall be deposited with the Director or the Administrator not later than ten (10) days following such demand. Upon such deposit, the Director or the Administrator shall surrender the original letter of credit to the Developer.
15-54.E.6 If the Developer fails or refuses to meet fully any of its obligations under this Ordinance or the applicable Waiver Community Ordinance, then the Director or the Administrator may, in his or her discretion, draw on and retain all or any of the funds remaining in the letter of credit. The Director or the Administrator thereafter shall have the right to take any action he or she deems reasonable and appropriate to mitigate the effects of such failure or refusal, and to reimburse the County or the Waiver Community from the proceeds of the letter of credit for all of its costs and expenses, including legal fees and administrative expenses, resulting from or incurred as a result of the Developer's failure or refusal to fully meet its obligations under this Ordinance or the applicable Waiver Community Ordinance. If the funds remaining in the letter of credit are insufficient to repay fully the County or the Waiver Community for all such costs and expenses, and to maintain a cash reserve equal to the required letter of credit during the entire time such letter of credit should have been maintained by the Developer, then the Developer shall, upon demand of the Director or the Administrator therefore, immediately deposit with the Director or the Administrator such additional funds as the Director or the Administrator determines are necessary to fully repay such costs and expenses and to establish such cash reserve.
15-55. Long-Term Access for Maintenance and Inspections.
15-55.A Access to privately-owned land for inspection and Maintenance of site runoff storage facilities, Compensatory Storage facilities, Major Stormwater System, and storm sewers covered by the Certification shall be through a grant of easement in a form approved by the Director, or the Administrator. Other instruments may be accepted by the Director, or Administrator, provided that the access and Maintenance rights granted runs with the land and survives title transfers.
15-55.B Subdivision site runoff storage areas, Compensatory Storage facilities, Major Stormwater System, and storm sewers not already located in dedicated rights-of-way or easements, shall be located either:
(i) on a Parcel granted or dedicated to, and accepted by, a public entity; or, (ii) on a Parcel, or Parcels, conveyed by plat as undivided equal interests to each lot in the subdivision or otherwise conveyed or dedicated to conservation or land preservation entities approved by the Director, or the Administrator.
15-55.C When title to the land underlying site runoff storage areas and storm sewers is conveyed in undivided equal interests to the owner(s) of each of the lots within the subdivision the following apply:
15-55.C.1 A covenant shall appear on the face of the plat of subdivision, and on each deed conveying ownership of a subdivision lot, which states that title to such site runoff storage facilities and storm sewers shall be held in undivided equal interests by each lot owner within the subdivision; and
15-55.C.2 A covenant shall appear on the face of the plat of subdivision, and on each deed conveying ownership of the subdivision lots, which states that in the event the governmental unit having easement rights under Section 15-55.A exercises its right to perform Maintenance to such subdivision runoff storage facilities and storm sewers, that governmental unit may lien each lot within the subdivision for the costs of any Maintenance work performed; and
15-55.C.3 An owners’ association may be established to provide for the Maintenance of the facilities, payment of property taxes, and the assessment and collection of owner dues or fees to fund said activities. Such associations shall be duly incorporated and the property owners' association’s declaration of covenants and bylaws shall be recorded against the title for all lots in that subdivision.
15-55.D When title to the land underlying the site runoff storage areas and storm sewers are located on privately-owned land not falling within the scope of Section 15-55.C, the following shall apply:
15-55.D.1 The Applicant shall reserve an easement for access for Maintenance and inspection purposes to any governmental unit having drainage and, or, stormwater management jurisdiction over the property; and
15-55.D.2 The Applicant shall record a covenant against title stating that in the event the governmental unit having easement rights under Section 15-55.A exercises its right to perform Maintenance to site runoff storage facilities and storm sewers on that property, that governmental unit may lien the property for the costs of any Maintenance work performed.
15-58. Soil Erosion and Sediment Control General Requirements
15-58.A Soil erosion and sediment control features shall be considered as part of any Development’s initial site planning process. Soil erosion and sediment control related measures are required to be constructed and maintained for any land disturbance activity. The following factors shall be addressed:
15-58.A.1 The susceptibility of the existing soils to erosion
15-58.A.2 Existing native and mature vegetation
15-58.A.3 Existing natural or established drainage ways
15-58.A.4 The natural contours of the land
15-58.A.5 Development phasing
15-58.A.6 Emphasis first on erosion control, then sediment control.
15-58.A.7 Winter shutdown
15-58.B Temporary erosion and sediment control measures shall be functional and consistent with this Article of the Ordinance and the NPDES Stormwater Permit in effect prior to land disturbance activities.
15-58.C Soil disturbance shall be conducted in a manner that minimizes erosion. Areas of the Development Site that will not be graded shall be protected from construction traffic or other disturbance until stabilization of the disturbed areas has been completed.
15-58.D Soil stabilization measures shall include the use of temporary or permanent measures.
15-59. Soil Erosion and Sediment Control Plan Design Criteria
15-59.A Channels and adjoining properties shall be protected from erosion and sedimentation. Where concentrated flow leaves a Development Site, effective energy dissipation shall be placed onsite at discharge locations.
15-59.B Erosion control blanket shall be required on all interior site runoff storage facilities side slopes between normal water level and high water level.
15-59.C Erosion control blanket to be placed in wetland or Buffer shall be 100% biodegradable, unless an alternative material is approved by the Director or Administrator. This requirement does not include turf reinforcement mats or other structural materials necessary for high erosion or scour areas.
15-59.D Land disturbance activities in streams shall be avoided, where possible. If disturbance activities are unavoidable, the following requirements shall be met:
15-59.D.1 Temporary stream crossings shall be constructed of non- erosive material.
15-59.D.2 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.
15-59.E Soil erosion and sediment control measures shall be placed where there is a potential for erosion and sized appropriately for the tributary drainage area, and disturbed areas draining 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 288-00, or equivalent control measures) to control all off-site runoff from disturbed areas. The Filter Barrier shall be designed in accordance with the following:
15-59.E.1 The use of straw bales as a Filter Barrier or ditch check is prohibited.
15-59.E.2 Silt Fences can be used to intercept sheet flow only. Silt Fences cannot be used as velocity checks in ditches or swales, nor can they be used where they will intercept concentrated flows.
15-59.E.3 Ditch checks shall be constructed using non-erodible materials or prefabricated devices. Straw or hay bales are not acceptable.
15-59.E.4 Reinforced Silt Fences (normal Silt Fence reinforced with woven wire fencing) can be used to intercept sheet flow Runoff from disturbed areas greater than one acre.
15-59.E.5 All undisturbed wetland, Flood Plain, waters and Buffer areas shall, at a minimum, have a barrier of protection. The barrier shall be placed at the limits of soil disturbance and consist of :
15-59.E.5.a. A dual row of Silt Fence, and a row of orange construction fence; or
15-59.E.5.b. A dual Silt Fence barrier, with one of the fences being of high visibility material.
15-59.E.5.c. Alternative practices offering comparable protection to wetland, Flood Plain, waters, and Buffer may be used to prevent impact where applicable.
15-59.E.5.d. Additional soil erosion and sediment control measures may be required to adequately protect these sites.
15-59.F Disturbed areas with drainage areas of one (1) acre or greater, but fewer than 5 acres shall, at a minimum, be protected by a Sediment Trap or equivalent control measure at a point downslope of the disturbed area.
15-59.G Disturbed areas with drainage areas of five (5) acres or greater, shall, at a minimum, be protected by a Sediment Basin, in accordance with 15-59.H, with a perforated filtered riser pipe or equivalent control measure at a point downslope of the disturbed area.
15-59.H Sediment Basins shall have both a permanent pool (dead storage) and additional volume (live storage) with each volume equal to the Runoff amount of a 2 year, 6 hour event over the onsite hydrologically disturbed tributary drainage area to the Sediment Basin. The available sediment volume below normal water level, in addition to the dead storage volume, shall be sized to store the estimated sediment load generated from the site over the duration of the construction period. For construction periods exceeding 1 year, the 1 year sediment load and a sediment removal schedule may be submitted. If the site runoff storage basin for the proposed Development 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.
15-59.I Pumping sediment laden water into any Stormwater Facility that is not designated to be a sediment control measure, Sediment Trap, or Sediment Basin either directly or indirectly without filtration is prohibited.
15-59.J Water removed from traps, basins and other water holding depressions or excavations must first pass through a sediment control or filtration device. When dewatering devices are used, discharge locations shall be protected from erosion. Discharges shall be routed through an effective sediment control measure (e.g., Sediment Trap, Sediment Basin or other appropriate measure).
15-59.K All discharges to undisturbed area, stabilized area or watercourse shall be designed at a non-erosive velocity corresponding to the soil and vegetative cover of the undisturbed area.
15-59.L All storm sewers, storm drain inlets and culverts that are, or will be functioning during construction shall be protected by sediment control measures. The sediment and erosion control measures shall be maintained until the site is stabilized.
15-59.M A stabilized construction entrance of aggregate underlain with filter cloth, or graveled road, or access drive, or parking area of sufficient width and length, and/or vehicle wash down facilities, shall be provided to prevent soil from being tracked or deposited onto public or private roadways. Any soil reaching a public or private roadway shall be removed immediately, or as warranted, and transported to a controlled sediment disposal area.
15-59.N All temporary and permanent stormwater conveyance Channels, including ditches, swales, diversions, and the outlets of all Channels and pipes shall be designed and constructed to withstand velocities that have the potential to cause damage or soil erosion.
15-59.O Earthen embankments with constructed side slopes steeper than 3H:1V must be constructed with appropriate stabilization as approved by the Director or the Administrator.
15-59.P Temporary diversions shall be constructed, as necessary, to direct all Runoff through an effective sediment control measure (e.g., Sediment Trap, Sediment Basin or other appropriate measure).
15-59.Q To the extent possible, soil stockpile locations shall be shown on the soil erosion and sediment control plan.
15-59.R Soil stockpiles shall not be located in a drainageway, Flood Plain area or a designated Buffer, unless otherwise approved, under specific conditions to be established by the Director or Administrator.
15-59.S Stockpiles to remain in place more than three days shall be provided with soil erosion and sediment control measures.
15-59.T The Applicant shall provide adequate receptacles for the deposition of all construction debris generated during the Development process. The Applicant shall not cause, or permit, the dumping, depositing, dropping, throwing, blowing, discarding or leaving of construction material debris upon or into any Development Site, Channel, pond, Lake, wetland, Buffer or Waters of DuPage County. The Applicant shall maintain the Development Site free of uncontrolled construction debris. Construction site operators shall implement appropriate soil erosion and sediment control, and control waste such as, discarded Building materials, concrete truck washout, chemicals, litter, and sanitary waste that may cause adverse impacts to water quality.
15-59.U All temporary erosion and sediment control measures shall be removed within 30 days after final stabilization is achieved. Trapped sediment and other disturbed soils resulting from temporary measures shall be properly disposed of prior to permanent stabilization.
15-59.V Design criteria, standards and specifications for erosion and sediment control shall be taken from one of the following sources:
15-59.V.1 Handbooks: Standards and specifications contained in The Illinois Urban Manual, as amended, DuPage Appendix E Water Quality Best Management Practices Technical Guidance Manual and the IDOT Standard Specifications for Road and Bridge Construction.
15-59.V.2 Other design criteria, standards and specifications, provided prior written approval is obtained from the Administrator or Director.
15-59.W Applicant with land disturbing activities greater than 1 acre shall provide a statement acknowledging that the site complies with the IEPA NPDES ILR10 permit, if applicable.
15-60. Inspection. Inspections, remedial work, and record keeping for all soil erosion and sediment control related work shall be performed and documented by the Applicant in accordance with the requirements of Illinois Environmental Protection Agency General NPDES Permit No. ILR 10 for sites that fall within that jurisdiction.
15-63. PCBMPs are required to treat the stormwater runoff for pollutants of concern and reduce Runoff volume for all Developments, with the exceptions and exclusions noted below.Upon a documented finding by the Director or Administrator that providing PCBMPs is impractical, then the appropriate PCBMP fee-in-lieu shall be paid by the Applicant in lieu of providing full or partial PCBMPs.
15-63.A PCBMPs are waived for the following Developments:
15-63.A.1 When comparing the Impervious Area of the Pre- Development Site to the with-development Impervious Area of the same Development Site, excluding any areas of the Development Site for which PCBMPs have already been provided and maintained, and the Net New Impervious Area is less than 2,500 square feet in the aggregate since April 23, 2013; or
15-63.A.2 The Development is limited to the resurfacing of an existing roadway; or reconstruction of an existing roadway with less than 2,500 square feet of Net New Impervious Area per quarter mile being added compared to the pre-development condition; or the replacement of an existing culvert or bridge; or
15-63.A.3 The Development is a Regional Stormwater Management Development or a Flood Control Development which are also considered to be PCBMPs; or
15-63.A.4 The Development is a stream bank stabilization, natural area restoration, or Wetlands Mitigation bank Development, or off-site wetland Mitigation which in itself is considered a PCBMP; or
15-63.A.5 The Development is limited to the construction, or re- construction, of a pedestrian walkway/bike path, in which the pedestrian walkway/bike path shall not exceed sixteen (16) feet in width, including shoulders; and is being constructed for general public use; or
15-63.A.6 The Development is limited to the modification of an existing stormwater management facility to incorporate Best Management Practices which in itself is considered PCBMPs; or
15-63.A.7 The Development is a Water or Sewer Improvement Development; or
15-63.A.8 The Development is limited to construction or Maintenance of an underground or overhead utility conduit or line, with supports and appurtenances. This exception does not include Buildings, substations, pads, parking lots or other associated utility support facilities.
15-63.B The following are prohibited from providing on-site infiltration PCBMPs.
15-63.B.1 Fueling and vehicle maintenance areas.
15-63.B.2 Areas within 400 feet of a known Community water system well as specified, or within 100 feet of a known private
well, for Runoff infiltrated from commercial, industrial and institutional land uses. The Applicant shall use their best efforts to identify such zones from available information sources, which include the Illinois State Water Survey, IEPA, USEPA, DuPage County Health Department and the local municipality or water agency.
15-63.B.3 Areas where contaminants of concern, as identified by the USEPA or the IEPA prior to Development, are present in the soil through which infiltration would occur. For sites with a No Further Remediation (NFR) letter from the USEPA or IEPA, the Applicant shall determine whether or not structural barriers are part of the Mitigation strategy and account for such measures in the design.
15-63.B.4 Development in soils classified as Hydrologic Soils Group A by the NRCS.
15-63.B.5 Developments over soils with the seasonally high groundwater table within 2 feet of the surface.
15-64. Post Construction Best Management Practices Design Criteria.
15-64.A PCBMPs shall provide volume and pollutant control using one of the following practices:
15-64.A.1 Infiltration of 1.25 inches for all new impervious surfaces; or
15-64.A.2 Native vegetated wetland bottom site runoff storage basin; or
15-64.A.3 PCBMPs not constructed pursuant to Sections 15-64.A.1 or 15-64.A.2 shall be constructed in accordance with 15-64.C.
15-64.B Design criteria may be taken from the DuPage Appendix E Water Quality Best Management Practices Technical Guidance Manual or approved equivalent.
15-64.C If the practices listed under 15.64.A.1 or 15.64.A.2 are not utilized, then volume control and pollutant control shall be provided separately for all new impervious surfaces in accordance with the following criteria:
15-64.C.1 The required volume control shall be calculated as the product of the New Impervious Area and a 1.25” rainfall event. No abstractions are taken on the rainfall depth.
15-64.C.2 The volume calculated shall be subtracted from any volume of site runoff storage that is also required.
15-64.C.3 A control structure or underdrain, may be used provided that the draw down time is between 48 and 96 hours.
15-64.C.4 When a trench or other excavation is used, the expected void space (typically no greater than 36%) within the uniformly graded stone, sand or aggregate portion of the fill material may be included in the volume calculation. Silt sized particles (1/16 mm) or smaller may not be used to complete this calculation. The design shall incorporate measures to protect the void space from long term deposition of fine sediments. If testing is completed on samples of the proposed fill material which indicates a higher level of porosity, the Applicant may submit the analysis completed on the material along with the storage calculations.
15-64.C.5 The bottom/invert of the trench shall be set above the seasonally high water table.
15-64.C.6 Applicants shall identify the pollutants of concern that may be generated by the proposed Development from the following list: Total Suspended Soils (TSS): Metals and Oils; and Nutrients consisting of nitrogen and phosphorous. Proposed PCBMPs shall only be required to treat those pollutants identified and agreed to by the Director or Administrator.
15-65. Required PCBMPs for a Development may be located off-site as part of a regional stormwater device, practice or system, but must be within the same major Watershed as the Development. The 6 major Watershed divisions within the County are identified in Section 15-5.B.
15-71. Site Runoff Conveyance Requirements
15-71.A Minor Stormwater Systems shall be sized to convey Runoff from the tributary Watershed under fully developed conditions consistent with the design requirements of the local jurisdiction.
15-71.B Major Stormwater Systems shall be sized to carry the Base Flood without causing additional property damage.
15-71.C Design runoff rates shall be calculated by methodologies in general use for such purposes at the time of application. Stormwater Facilities draining more than 5-acres shall use event hydrograph methods. The Director in a Non-Waiver Community or the Administrator in a Partial Waiver or Complete Waiver Community may specify certain design tools and methodologies to be used within the respective Community.
15-71.D Any design runoff rate method shall use Illinois State Water Survey Bulletin 71 70 northeast sectional rainfall statistics, or for continuous simulations, the National Oceanic and Atmospheric Administration continuous rainfall record from 1949 to present at the Wheaton gage, and shall calculate flow from all tributary area upstream of the point of design. Facilities with a tributary area over 100-acres will be required to perform Critical Duration analysis and use the highest peak discharge for conveyance design, testing events up to a 24-hour duration.
15-71.E Maximum flow depths at the crown of a roadway or the edge of pavement at the high side of a super elevated roadway shall not exceed six inches during the Base Flood condition. This requirement does not apply to the at-grade repair, resurfacing or in-kind replacement of a roadway existing prior to the effective date of this Ordinance.
15-71.F Transfers of waters between the major planning Watersheds shall be prohibited except when such transfers will not violate the provisions of Section 15-27.A.
15-71.G Stormwater Facilities for Runoff upstream of Flood protection facilities shall provide for conveyance or storage of Flood waters without increased potential for damage to real or personal property during Base Flood conditions.
15-72. Site Runoff Storage. Site runoff storage facilities, consisting of site runoff storage and a control structure with an emergency overflow shall be required for all Developments.
15-72.A The following cases or special conditions represent exceptions to providing site runoff storage:
15-72.A.1 When comparing the Impervious Area of the pre- development Development Site as it existed as of February 15, 1992 to the with-development Impervious Area of the same Development Site, excluding any areas of the Development Site for which detention has already been provided, and the Impervious Area has not increased by a minimum of 25,000 sq. ft cumulatively of permitted Development; or
15-72.A.2 When comparing the highest percentage of Impervious Area of the same Development Site in the 3-years immediately prior to the date of the Stormwater Management Certification application to the with-development Impervious Area the percentage will decrease by a minimum of 5%; or
15-72.A.3 The with-development Impervious Area of the same
Development Site is less than or equal to10%; or,
15-72.A.4 The Development is strictly limited to a Roadway Development intended for public use, and the with-development Impervious Area is less than 25,000 square feet compared to pre-development conditions.
15-72.B When the Development is either a Roadway Development or an Open Space Development, which are “Special Cases of Development” as noted in Section 15-41, then only “Site Runoff Storage Special” is required. Site Runoff Storage Special shall be only that volume of site runoff storage required such that pre-development peak discharges for the 2-year, 24-hour duration and the 100-year, 24-hour duration rainfall events are not increased.
15-72.C The following “Special Cases of Development” are not required to provide Site Runoff Storage or “Site Runoff Storage, Special”:
15-72.C.1 Bridge and culvert modification, repair, and replacement
15-72.C.2 Streambank stabilization Developments; or
15-72.C.3 Natural area restoration Developments; or
15-72.C.4 Wetland Mitigation sites and wetland Mitigation banks; or
15-72.C.5 Trails, bikeways and pedestrian walkways that shall not exceed sixteen (16) feet in width, including shoulders; and are being constructed for general public use; or
15-72.C.6 Water and Sewer Improvement Developments and all underground utilities.
15-72.D When site runoff storage is required, it will be calculated as a volume utilizing the following Development parameters and procedures.
15-72.D.1 The area for which site runoff storage is to be calculated will be the limits of grading or land cover disturbance, or a combination, whichever encompasses the greatest area of the Development Site, and will also include any Development area for which site stormwater storage was deferred in Section 15- 72.A.1.
15-72.D.2 The Runoff characteristics of the area will be indexed by calculating a representative hydrologic parameter. This parameter will be the NRCS Curve Number unless the Administrator approves the use of some other generally accepted engineering practice.
15-72.D.3 The design rainfall depth and duration will be the 100- year, 24-hour duration ISWS Bulletin 71 70 rainfall depth. Sectional statistics and rainfall distributions by Huff appropriate
for a 100-year, 24-hour event shall be used unless some other rainfall and distribution is approved by the Administrator.
15-72.D.4 For purposes of calculating the required volume, a control structure shall be assumed that limits the peak runoff from the site to 0.10 cfs/acre for the disturbed area.
15-72.D.5 For sites less than 5-acres in area, the unit area site runoff storage nomograph from the Northeastern Illinois Planning Commission (now known as CMAP) publication “Investigation of Hydrologic Methods for Site Design in Northeastern Illinois” (Dreher and Price, 1991) will be considered an acceptable calculation methodology for determining the volume of site runoff storage required in lieu of modeling.
15-72.D.6 For sites 5-acres or greater, a hydrologic model that produces a runoff hydrograph shall be utilized, and the runoff hydrograph routed through a basin which provides sufficient storage such that the combination of control structure and runoff storage volume limits the discharge to the allowable peak runoff. The calculated volume is then the required site runoff storage volume. This volume may be reduced by any volume control BMP (see Article VIII) volume if such a volume is required, and is then referred to as the Modified Required Site Runoff Storage Volume.
15-72.D.7 On Development Sites that have an existing site runoff storage facility, the volume of site runoff storage required, for a proposed Development shall not be less than the volume on- site pre-development, regardless of the provisions of this section.
15-72.E The details of the design of a site runoff storage facility, which includes a site runoff storage control structure in accordance with Section 15-73 (sideslopes, depths, etc.), will be in accordance with any applicable ordinances of the Waiver Community or in the unincorporated County, those of the County.
15-72.F If a Development is granted a Variance with respect to the required site runoff storage volume, then the Applicant shall pay a fee- in-lieu of site runoff storage per Section 15-97.
15-72.G Small areas of the disturbed area of a Development Site (less than 5% cumulatively) that are impractical to drain to a site runoff storage facility (backslopes of landscaping berms for example) may be allowed to drain off-site without routing through a site runoff storage facility provided that the areas are primarily vegetated and contain only incidental amounts of impervious surfaces such as sidewalks, utility appurtenances, or trails. Such areas do not “penalize” the allowable release rate by subtracting the anticipated 100-year discharge from these areas from the release rate, but may not be included in the area used for calculating the allowable release rate.
15-73. Site Runoff Storage Control Structures
15-73.A A site runoff storage facility requires a control structure to meet the peak runoff rate requirements. Its design will be as follows, unless an alternate design meeting the intent to provide site runoff storage of a determined volume is approved by the Administrator.
15-73.A.1 The Structure shall be designed so that within the elevation range at which the site runoff storage volume is provided, the calculated discharge from the Structure equals the product of 0.10 cfs/acre multiplied by the disturbed site area, assuming a free discharge.
15-73.A.2 An overflow conveyance system shall also be designed to convey a minimum design rate of 1-cfs/acre multiplied by the entire upstream drainage area without damaging any Buildings on site with overbank Flooding, and shall discharge at the same location as where water leaves the site pre-development. This location may be modified by the Administrator. This conveyance shall begin operation at the elevation at which the site runoff storage volume is met. If 100-acres or greater drains to the emergency overflow then the overflow is part of the major drainage system and it also falls under the provisions of Article X.
15-73.B For locations draining more than 5 acres, but less than 100- acres, the combination of control structure, site runoff storage and overflow conveyance shall be tested in a with-development hydrologic model and the design shall be further modified by adding additional site runoff storage, as necessary so that the Pre-Development Site 2-year and 100-year, 24-hour duration peak discharges are not increased compared to the with Development Site condition.
15-73.C For site runoff storage facilities with a tributary area 100 acres or greater at the control structure, in addition to the above requirements, the combination of control structure, site runoff storage and overflow conveyance shall not exceed the Pre-Development Site peak discharge in a 2-yr and 100-yr rainfall event of Critical Duration up to a 24-hour duration.
15-73.D Unless approved by the Director or the Administrator, all site runoff storage control structure designs shall operate without human intervention and, when requiring electric power, shall have at least two independent and Flood resistant sources of power.
15-74. Storage facilities located within the Regulatory Flood Plain shall:
15-74.A Conform to all applicable requirements specified in Article X of this Ordinance; and
15-74.B Store the required site runoff under all stream flow and backwater conditions up to the Base Flood Elevation; and
15-74.C Not allow design release rates to be exceeded under any stream elevation less than the Base Flood Elevation.
15-75. Storage facilities located within the Regulatory Floodway shall:
15-75.A Meet the requirements for locating storage facilities in the
Regulatory Flood Plain; and
15-75.B Be evaluated by performing hydrologic and hydraulic analysis consistent with the standards and requirements for Watershed Plans; and
15-75.C Provide a Watershed Benefit.
15-76. Storage facilities may be located off-site if the following conditions are met:
15-76.A The off-site storage facility meets all of the requirements of this Article IX; and
15-76.B Adequate storage capacity in the off-site facility is dedicated to the Development; and
15-76.C The Development includes provisions to convey stormwater to the off-site storage facility.
15-77. Modifications to drainage tiles.
15-77.A Any modification of a drainage tile shall comply with the Illinois Drainage Code. For the purpose of determining compliance with this provision, a modification to a drainage tile shall:
15-77.A.1 Preserve the existing tile system’s drainage characteristics; and
15-77.A.2 Drain tiles located wholly on property under the control of the Developer may be removed or disabled provided that such removal does not cause additional Flood damages; and
15-77.A.3 Drain tiles may be discharged as surface flow within a Development Site provided that no obstruction to the predicted flow from offsite areas will occur, and the general provisions of Section 15-27.A are not violated; and
15-77.A.4 Development designs may only utilize, where practical and approved by the Director or Administrator, outflow locations with an existing drain tile leaving the Development Site with the permission of downstream landowners unless the tile is owned and maintained by a unit of government; and
15-77.A.5 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; and
15-77.A.6 Drain tiles shall be replaced or intercepted and connected to the proposed stormwater management system or a storm sewer bypass, which system or bypass shall be of an equivalent size and capacity. The capacity shall be determined by either the capacity of the existing tile flowing full, in its original condition, or the existing downstream capacity, whichever is more restrictive. A flow restrictor structure shall be required as necessary to achieve the capacity requirements; and
15-77.A.7 Drain tile systems disturbed by Development activities shall be reconnected unless the approved drainage plan provides otherwise.
15-77.B Existing, replaced or re-routed tiles within a Development Site shall be treated as part of the minor drainage system. The type, size, location and inverts shall be shown on the Record Drawings of the Development and any further modification to such tiles, or the repair or removal of damaged tiles, shall require the approval of the Director or the Administrator.
15-77.C When subsurface Drainage Tiles are detected on a Pre- Development Site the Applicant shall submit the following:
15-77.C.1 A subsurface drainage inventory including the locations of identified drainage tiles by means of slit trenching and other appropriate methods performed by a qualified subsurface drainage consultant. Any drain tile lines damaged during the investigation shall be repaired to their previous working status.
15-77.C.2 A topographical map of the Development Site showing: 15-77.C.2.a. Location of and depth of each slit trench, to correspond with the tile investigation report and surveyed points where the tile was field staked at approximately 50 foot intervals; and
15-77.C.2.b. Location of each drain tile with a flow direction arrow, tile size, and any connection to adjoining properties. A summary of the tile investigation report showing trench identification number, tile size, material and quality, percentage of the tile filled with water, percentage of restrictions caused by silting, depth of ground cover, and working status; and
15-77.C.2.c. The qualifications of the Person or firm conducting tile location investigation.
15-77.D Replacement of downstream drain tiles shall be required if the Development Site depends on those tiles for stormwater conveyance or water surface elevation control. Replacement of the downstream drain tiles is not required if a maintainable outlet for the site exists or is installed. Drainage tiles may be maintained, replaced or repaired for agricultural land use when undertaken in compliance with NRCS approved farming practices without requiring Stormwater Management Certification.
15-80. Determination of Regulatory Flood Plain, Base Flood Elevation (BFE), and
15-80.A The BFE for purposes of establishing the low opening on New Construction of Buildings shall be taken from the higher of BFEs established by the current regulatory profile, or elevations established and published by the Director which meet the following conditions:
15-80.A.1 The Director certifies that adequate review and quality control has been performed on the hydrologic/hydraulic modeling, and BFEs have been established using acceptable methodology; and
15-80.A.2 The Director notifies an affected Community within the studied reach and makes available to that Community working input files for the hydrologic/hydraulic model; and
15-80.A.3 The Director publishes notice that the model will be used for the purpose of regulating new Building construction.
15-80.B The BFE for purposes of establishing Compensatory Storage will be based on the current regulatory model as determined in 15-80.D.
15-80.C If neither elevation identified in this section has been established, then the BFE shall be determined in accordance with 15-80.D.2.
15-80.D The regulatory BFE shall be taken as the 1% chance storm established from Flood Plain studies that have been completed and adopted by FEMA as the Regulatory Flood Plain. When a BFE has not been adopted by FEMA as regulatory, the following hierarchy of Flood Plain studies shall be used to determine the BFE:
15-80.D.1 Flood Plain studies that have been published by the Director in accordance with Section 15-80.A.
15-80.D.2 If no Regulatory Flood Plain study or model published by the Director is available and the Development includes a Channel with a tributary area 100 acres or greater, or a depressional storage area with 20 acres or greater of tributary area, a site specific Flood Plain study shall be required and the BFE shall be determined using FEMA-accepted models and methodology. If the chosen model is not FEQ, the BFE shall be based on the Critical Duration.
15-80.E Where a Channel has a tributary drainage area equal to or greater than 640 acres, the site specific Flood Plain study completed in Section 15-80.D.2 shall be submitted to IDNR-OWR for approval or other designee.
15-80.F The Regulatory Floodway shall be as delineated on the maps listed in Exhibit 2. Where interpretation is required to determine the exact location of the Regulatory Floodway, IDNR-OWR shall be contacted or their designee.
15-80.G If a Floodway is not designated on the maps in Exhibit 2 and the tributary area is one square mile or greater, IDNR-OWR Part 3708 rules shall apply. If a Floodway is not designated on the maps in Exhibit 2 and the tributary area is less than one square mile, then the Regulatory Flood Plain shall have no designated Floodway.
15-80.H The Flood Protection Elevation (FPE) is the BFE plus one foot of freeboard.
15-81. Regulatory Flood Plain Development Performance Standards
15-81.A General Performance Standards
15-81.A.1 No Development activity within the Flood Plain shall result in an Adverse Hydraulic Impact to upstream or downstream properties.
15-81.A.2 Proposed Developments that meet the following criteria shall be exempt from the hydrologic and hydraulic modeling requirements set forth in the Ordinance:
15-81.A.2.a. A Development that is located in the Regulatory Flood Plain but is located entirely outside of the Regulatory Floodway, provided the Development meets the Compensatory Storage requirements of Section 15-81.D.
15-81.A.2.b. The construction of an at-grade pedestrian path located within the Regulatory Floodway, provided the proposed Development meets the following requirements which results in a Development that does not increase the BFE:
15-81.A.2.b.1. The Development must have an at-grade intention, with a reasonable balance of cut and fill at each cross-section based on the judgment of the Director. Net cut over the length of the Development is acceptable where a balance of cut and fill at every cross-section cannot be achieved.
15-81.A.2.b.2. The maximum width of the proposed path is sixteen (16) feet of traveled lane, including shoulders.
15-81.A.2.c. The construction of a public safety feature, such as a pedestrian bridge railing or a guard rail for a roadway, provided the proposed construction of a public safety feature does not result in a loss of 10% or more of the existing conveyance cross-sectional area.
15-81.A.2.d. Developments replacing culverts with a hydraulically equivalent culvert(s).
15-81.A.3 A CLOMR shall be required for any Development that either: (1) revises the Regulatory Floodway boundary or (2) encroaches upon a Flood Plain and causes a specified increase in the BFE, in accordance with FEMA and State regulations.
15-81.A.4 In accordance with NFIP Regulations, a building permit shall not be issued for construction in the SFHA until a LOMR is issued by FEMA unless the Building meets the Building protection standards in Section 15-81.B. A building permit for a compliant Structure can be issued without a LOMC.
15-81.A.5 A copy of an application for a LOMC to remove a property from the SFHA including all the required information, calculations, and documents shall be submitted to the Department and Waiver Community concurrent with the application to FEMA or IDNR-OWR or its designee.
15-81.A.6 In areas outside the Regulatory Floodway but within the Flood Plain, maximum flow depths on new parking lots that are used for permanent parking shall not exceed one foot during the Base Flood condition and shall be designed for protection against physical Flood damages. Parking areas that are used solely for the purpose of overflow, temporary, or short-term parking may allow Flood depths greater than one foot. Parking in areas below the Base Flood Elevation shall be clearly posted with Flood Hazard signs.
15-81.B Building Protection Standards
15-81.B.1 If a proposed Building is located in a SFHA, all New Construction and Substantial Improvements shall (i) be designed (or modified) and adequately anchored to prevent flotation, collapse, or lateral movement of Building resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy. (ii) be constructed with materials resistant to Flood damage, (iii) be constructed by methods and practices that minimize Flood damages, and (iv) be constructed with electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of Flooding. Existing Buildings that have not incurred Substantial Damage or meet the Substantial Improvement criteria may also be modified based on the above criteria. All construction below the FPE shall be of Flood resistant materials and conform to provisions in FEMA/FIA Technical Bulletin 2. All electrical, heating, ventilation, air conditioning, plumbing, and other appliances shall be located above the FPE. Storage of materials shall be in accordance with Section 15-81.C.1, which states that there can be no storage of certain listed materials below the FPE.
15-81.B.2 New Construction or Substantial Improvements of residential Buildings within a SFHA shall have the Lowest Floor elevated to at least the FPE and that the fully enclosed areas below the Lowest Floor that are usable solely for parking of vehicles, Building access or storage in an area other than a basement and which are subject to Flooding shall be designed to automatically equalize hydrostatic Flood forces on exterior walls by allowing for the entry and exit of Floodwaters. Designs for meeting this requirement must either be certified by a registered Professional Engineer or architect or meet or exceed the following minimum criteria: A minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to Flooding shall be provided. The bottom of all openings shall be no higher than one foot above grade. Openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of Floodwaters. Adequate drainage shall be provided.
15-81.B.3 New Construction and Substantial Improvements of non-residential Buildings within a SFHA shall (i) have the Lowest Floor elevated to at least the FPE or, (ii) together with attendant utility and sanitary facilities be designed so that below the FPE the Building is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. Where a non- residential Structure is intended to be made watertight below the FPE, (i) a registered Professional Engineer or architect shall develop and/or review structural design, specifications, and plans for the construction, and shall certify that the design and methods of construction are in accordance with accepted standards of practice for meeting the applicable provisions of 44CFR60.3 and (ii) a record of such certificates which includes the specific elevation (in relation to sea level) to which such Buildings are Floodproofed shall be maintained by the official designated by the Community under 44CFR59.22.
15-81.B.4 Manufactured Homes that are placed or substantially improved within the SFHA on sites (i) outside of a Manufactured Home Park or subdivision, (ii) in a New Manufactured Home Park or subdivision, (iii) in an Expansion to an Existing Manufactured Home Park or subdivision, or (iv) an Existing Manufactured Home Park or subdivision on which a Manufactured Home has incurred Substantial Damage as the result of a Flood be elevated on a permanent foundation such that the Lowest Floor of the Manufactured Homes to at least the FPE, be securely anchored to an adequately anchored foundation system to resist floatation, collapse and lateral movement in accordance with the rules and regulations for the Illinois Mobile Home Tie-Down Act issued pursuant to 77 Ill. Adm. Code 870, provide adequate access and drainage and if pilings are used for elevation, applicable design and construction standards for pilings shall be met.
15-81.B.5 Manufactured Homes to be placed in an Existing Manufactured Home Park or subdivision within the SFHA not subject to the provisions of Section 15-81.B.4 shall be elevated so that either (i) the Lowest Floor of the Manufactured Home is at least the FPE, or (ii) the Manufactured Home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than 36 inches in height above grade and be securely anchored to an adequately anchored foundation system to resist floatation, collapse, and lateral movement accordance with the rules and regulations for the Illinois Mobile Home Tie-Down Act issued pursuant to 77 Ill. Adm. Code 870, provide adequate access and drainage and if pilings are used for elevation, applicable design and construction standards for pilings shall be met.
15-81.B.6 Recreational Vehicles placed on sites within a SFHA be either (i) be on the site for fewer than 180 consecutive days, (ii) be fully licensed and ready for highway use, or (iii) meet the permit requirements of 44CFR60.3(b)(1) and the elevation and anchoring requirements of Section 15-81.B.4. A Recreational Vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by a quick disconnect type utilities and security devices, and has no permanently attached additions.
15-81.B.7 Accessory Structures such as detached garages and sheds may be constructed within a SFHA if they meet all of the following criteria:
15-81.B.7.a. Must be non-habitable, used for the storage of vehicles and tools, and cannot be modified later into another use.
15-81.B.7.b. Shall be located outside of the Regulatory Floodway.
15-81.B.7.c. Shall be on a single lot and be accessory to an existing principal Building on the same lot.
15-81.B.7.d. When the floor of an Accessory Structure is below the BFE, the walls of the Accessory Structure shall include openings to allow Floodwater to enter the Structure from the adjacent grade to the BPE. The location of the openings and the size of each opening shall be in accordance with FEMA Technical Bulletin 1.
15-81.B.7.e. All electrical, heating, ventilation, air conditioning, plumbing, and other appliances, or fixed mechanical or electrical devices shall be located above the FPE.