CHAPTER 5.12:
POST-CONSTRUCTION STORMWATER RUNOFF
Section
5.12.040 Submittals, review, and approval
5.12.010 INTRODUCTION/PURPOSE.
During the construction process, soil is highly vulnerable to erosion by wind and water. Eroded soil endangers water resources by reducing water quality and causing the siltation of aquatic habitats for fish and other species. Eroded soil also necessitates repair of sewers (sanitary sewers are owned and operated by the City of Indianapolis) and ditches and the dredging of lakes. In addition, clearing and grading during construction cause the loss of native vegetation necessary for terrestrial and aquatic habitats. Following the completion of construction activities, dust, dirt, erosion, and runoff from developed areas (parking lots, driveways, rooftops, roadways, etc.) will continue to affect the stormwater facilities and receiving streams unless post-construction practices are implemented during construction and are maintained in perpetuity.
As a result, the purpose of this chapter is to safeguard persons, protect property, and prevent damage to the environment within the City. This chapter will also promote public welfare by guiding, regulating and controlling the design, construction, use, and maintenance of any development or other activity that disturbs or breaks the topsoil or results in the movement of earth within the City.
This chapter establishes minimum stormwater management requirements and controls for the protection of general health, safety, and welfare of the public residing in watersheds within this jurisdiction. This chapter seeks to meet that purpose through the following objectives:
(A) Minimize increases in stormwater runoff from any development in order to reduce flooding, siltation, increases in stream temperature, and stream bank erosion and maintain the integrity of stream channels;
(B) Minimize increases in non-point source pollution caused by stormwater runoff from development which would otherwise degrade local water quality;
(C) Minimize the total annual volume of surface water runoff which flows from any specific site during and following development as not to exceed the predevelopment hydrologic regime to the maximum extent practicable;
(D) Reduce stormwater runoff rates and volumes, soil erosion, and non-point source pollution, wherever possible, through stormwater management controls and to ensure that these management controls are properly maintained and pose no threat to public safety.
Although the City of Southport is located within the City of Indianapolis, Marion County, it is a separate entity charged with establishing its own requirements concerning post-construction stormwater runoff control. This chapter is based upon and references the City of Indianapolis Storm Water Design and Construction Specifications Manual, approved by the Department of Public Works on July 25, 2001, in an effort to promote county-wide uniformity as it relates to post-construction stormwater runoff control regulations. (Ord. 5.09, passed 2-19-2007)
5.12.020 DEFINITIONS.
ACCELERATED EROSION. Erosion caused by development activities that exceeds the natural processes by which the surface of the land is worn away by the action of water, wind, or chemical action.
AGRICULTURAL LAND-DISTURBING ACTIVITY. Tillage, planting, cultivation, or harvesting operations for the production of agricultural or nursery vegetative crops; also includes pasture renovation and establishment, the construction of agricultural conservation practices, and the installation and maintenance of agricultural drain tiles. This does not include the construction of agricultural-related facilities such as barns, buildings to house livestock, agricultural waste lagoons, and other infrastructure.
APPLICANT. Property owner or agent of a property owner who has filed an application for a site development permit.
BEST MANAGEMENT PRACTICES (BMPs). Structural measures (wetlands, ponds, sand filters, etc.), nonstructural measures (restrictive zoning, reduced impervious areas, etc.), or a combination of practices that are designed to act as effective, practicable means of minimizing the impacts of development and human activities on water quality and quantity.
BMP OWNER. Typically, the property owner. The BMP owner may also be the leasee of property in the case of long-term leases of commercial or industrial zoned properties. The leasee is considered the BMP owner only if the lease specifically states that construction by the leasee must meet applicable local codes and regulations.
CHANNEL. A natural or artificial watercourse with a definite bed and banks that conducts continuously or periodically flowing water.
CITY OF INDIANAPOLIS STORMWATER DESIGN AND CONSTRUCTION SPECIFICATIONS MANUAL. The guidebook providing recommendations and requirements for engineering design and construction standards for proper stormwater management for those engineers, builders, contractors, land planners, and property owners contemplating some form of land alteration within the City of Indianapolis, Marion County, Indiana. A copy of the manual can be found on the Internet at the following web address:
http://www.indy.gov/eGov/City/DPW/Business/Specs/Pages/UpdatedStormWaterManual.aspx
CONTRIBUTING DRAINAGE AREA. The total drainage area to a given point, including off-site drainage.
DETENTION. The temporary storage of storm runoff in a stormwater management practice with the goals of controlling peak discharge rates and providing gravity settling of pollutants.
DETENTION FACILITY. A detention basin or alternative structure designed for the purpose of temporary storage of stream flow or surface runoff and gradual release of stored water at controlled rates.
DEVELOPER. A person who undertakes land disturbance activities.
DRAINAGE EASEMENT. A legal right granted by a landowner to a grantee allowing the use of private land for stormwater management purposes.
EFFECTIVE DRAINAGE AREA. The drainage area from a specific site, excluding off-site drainage, where off-site drainage either does not exist or where off-site drainage bypasses the site through culverts or other means.
EROSION. The detachment and movement of soil, sediment, or rock fragments by water, wind, ice, or gravity.
EROSION AND SEDIMENT CONTROL PLAN. A plan that is designed to minimize the accelerated erosion and sediment runoff at a site during construction activities.
GRADING. The cutting and filling of the land surface to a desired slope or elevation.
IMPERVIOUS AREA. An area where the land surface has been altered in such a way that it decreases the amount of rainwater infiltration. Impervious surfaces include, but are not limited to, paved roads, paved driveways, rooftops, and parking lots.
INDUSTRIAL STORMWATER PERMIT. A National Pollutant Discharge Elimination System (NPDES) permit issued to a commercial industry or group of industries which regulates the pollutant levels associated with industrial stormwater discharges or specifies on-site pollution control strategies.
INFILTRATION. The process of percolating stormwater into the subsoil.
INFILTRATION FACILITY. Any structure or device designed to infiltrate retained water to the subsurface. These facilities may be above grade or below grade.
JURISDICTIONAL WETLAND. An area that is inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support a prevalence of vegetation typically adapted for life in saturated soil conditions, commonly known as hydrophytic vegetation.
LAND DISTURBANCE ACTIVITY. Any activity which changes the volume or peak flow discharge rate of rainfall runoff from the land surface. This may include the grading, digging, cutting, scraping, or excavating of soil, placement of fill materials, paving, construction, substantial removal of vegetation, or any activity which bares soil or rock or involves the diversion or piping of any natural or manmade watercourse.
MEASURABLE STORM EVENT. A precipitation event that results in a total measured precipitation accumulation equal to, or greater than, one-half inch of rainfall.
NON-POINT SOURCE POLLUTION. Pollution from any source other than from any discernible, confined, and discrete conveyances, and shall include, but not be limited to, pollutants from agricultural, mining, construction, subsurface disposal and urban runoff sources.
OFFLINE STRUCTURE. A BMP that treats only the water quality volume (WQv). Flows exceeding the WQv bypass the structure and reenter the watercourse below the BMP.
OFF-SITE FACILITY. A stormwater management measure located outside the subject property boundary described in the permit application for land development activity.
ON-SITE FACILITY. A stormwater management measure located within the subject property boundary described in the permit application for land development activity.
POST-CONSTRUCTION RUNOFF CONTROL PLAN. A plan designed to permanently control the quantity of stormwater runoff, minimize erosion and sediment runoff, and reduce the migration of various pollutants from developed areas (e.g., parking lots, driveways, rooftops, etc.) upon completion of construction/reconstruction activities.
RECHARGE. The replenishment of underground water reserves.
REDEVELOPMENT. Any construction, alteration, or improvement where structures are removed and/or replaced. Where the disturbance caused by redevelopment activities disturbs less than one acre, no post-construction runoff control plan shall be required.
RULE 5. Indiana law (327 327 15-5-5) requiring erosion control practices on construction projects disturbing greater than one acre of land. This rule was developed by the Indiana Department of Environmental Management (IDEM) to meet federal Environmental Protection Agency (EPA) requirements. The purpose of the Rule 5 permit is to establish requirements to protect State waters from adverse effects from stormwater discharge from construction activities.
RULE 13. Indiana law (327 327 15-13) regulating MS4 (Municipal Separate Storm Sewer System) entities (cities, town, universities, colleges, hospitals, military bases, etc.) located within mapped urbanized areas, as delineated by the U.S. Census Bureau, or, for those MS4 areas outside of urbanized areas, serving an urban population greater than 7,000 people. The rule applies to the portions of an urban federal, state, municipal, county, public or private entity stormwater conveyance system that are not combined with sewage conveyances.
STOP-WORK ORDER. An order issued which requires that all construction activity on a site be stopped.
STORMWATER QUALITY MANAGEMENT. A system of vegetative, structural, and other measures that reduce or eliminate pollutants that might otherwise be carried by surface runoff.
STORMWATER RUNOFF. Flow on the surface of the ground, resulting from precipitation.
STORMWATER TREATMENT PRACTICES (STPs). Measures, either structural or nonstructural, that are determined to be the most effective, practical means of preventing or reducing point source or non-point source pollution inputs to stormwater runoff and water bodies.
SUBDIVISION. Any land that is divided or proposed to be divided into lots, whether contiguous or subject to zoning requirements, for the purpose of sale or lease as part of a larger common plan of development or sale.
TSS. Total suspended solids.
TREATMENT TRAIN. More than one BMP in series treating stormwater runoff. Such configurations are necessary when BMPs individually cannot meet the 80% TSS reduction goal.
WATER QUALITY VOLUME (WQv). The storage needed to capture and treat the runoff from the first one inch of rainfall. In numerical terms, it is equivalent to an inch of rainfall multiplied by the volumetric runoff coefficient and the site area. Refer to the City of Indianapolis Storm Water Design and Construction Specifications Manual for the equation and variable descriptions.
WATERSHED. The total drainage area contributing runoff to a single point. (Ord. 5.09, passed 2-19-2007)
5.12.030 APPLICABILITY.
(A) The requirements under this chapter are in compliance with 327 327 15-5 (Rule 5) and apply to all persons meeting the requirements of 327 327 15-5-2. In general, this chapter requires the control of polluted runoff from construction and improvement sites with a land disturbance greater than or equal to one acre, or disturbances of less than one acre of land that are part of a larger common plan of development or sale if the larger common plan will ultimately disturb one acre or more of land.
(B) The requirements under this chapter do not apply to persons who are involved in agricultural land-disturbing activities or forest harvesting activities.
(C) The requirements under this chapter do not apply to the following activities, provided other applicable permits contain provisions requiring immediate implementation of soil erosion control measures:
(1) Landfills that have been issued a certification of closure under 329 329 10.
(2) Coal mining activities permitted under I.C. 14-34.
(3) Municipal solid waste landfills that are accepting waste pursuant to a permit issued by the department under 329 329 10 that contains equivalent stormwater requirements, including the expansion of the landfill boundaries and construction of new cells either within or outside the original solid waste permit boundary.
(D) In addition to the requirements of this chapter, post-construction runoff control plans shall be developed in accordance with the City’s stormwater quality management plan, the State of Indiana Storm Water Quality Manual, and the City of Indianapolis Storm Water Design and Construction Specifications Manual in order to ensure that established water quality standards will be maintained during and after development of the site and that post-construction runoff levels are consistent with any local and regional watershed plans. By reference, the following portions of the City of Indianapolis Storm Water Design and Construction Specifications Manual (CISWDCSM), as adopted July 25, 2001, by the Indianapolis Department of Public Works, are incorporated into this chapter:
|
CISWDCSM Section |
Topic |
|---|---|
|
101.01 |
Section Purpose |
|
102.06 |
Operations and Maintenance Manual |
|
103.04 |
Drainage fees (see “Miscellaneous Fees – 5. BMP Inspection Fees” on page 1-12) |
|
104.02 |
Storm Water Quality |
|
701.02 |
Definitions |
|
701.03 |
Purpose and Background |
|
701.04 |
Storm Water Quality Control Requirements |
|
702.00 |
Structural Best Management Practices |
|
702.01 |
Innovative BMP’s |
|
702.03 |
Storm Water Ponds (includes Design Considerations and Operation, Maintenance, and Management Inspection Checklist) |
|
702.04 |
Storm Water Wetlands (includes Design Considerations and Operation, Maintenance, and Management Inspection Checklist) |
|
702.05 |
Bioretention (includes Design Considerations and Operation, Maintenance, and Management Inspection Checklist) |
|
702.06 |
Sand Filters (includes Design Considerations and Operation, Maintenance, and Management Inspection Checklist) |
|
702.07 |
Water Quality Swales (includes Design Considerations and Operation, Maintenance, and Management Inspection Checklist) |
|
702.08 |
Biofilters (includes Design Considerations and Operation, Maintenance, and Management Inspection Checklist) |
|
702.09 |
Catch Basin Inserts (includes Design Considerations and Operation, Maintenance, and Management Inspection Checklist) |
(E) In general, the post-construction runoff control plan includes permanent erosion, sediment, and runoff control measures that focus on reduction of total suspended solids (TSS) and other pollutants typical of parking lots, rooftops, driveways, and other developed areas.
The erosion and sediment control plan (refer to Chapter 5.16) addresses temporary control measures for the reduction of sediment migration during construction activities. Most of the measures often included in an erosion and sediment control plan are not intended for permanent installation, such as silt fences and straw bales. Vegetation installed prior to or during construction to alleviate sediment migration and erosion may be retained at the site after construction, pending approval by the City. In addition, some acceptable BMPs (refer to Section 5.12.050(C)) may be constructed for use during construction activities and retained at the site for permanent use once construction has been completed. (Ord. 5.09, passed 2-19-2007)
5.12.040 SUBMITTALS, REVIEW, AND APPROVAL.
(A) The applicant shall submit a complete post-construction runoff control plan and a complete erosion and sediment control plan in triplicate to the Clerk’s office at the Southport City Hall located at 6901 Derbyshire Rd., Southport, IN 46224.
A notice of intent letter (as described in Rule 5, 327 327 15-5-5) must be submitted with the post-construction runoff control plan and erosion and sediment control plan. If the City would like to incorporate review comments, these comments shall be forwarded to the applicant within 45 days of the date of the plan submittal.
(B) At the time of submittal, the date and time will be recorded.
(C) Each application shall bear the name(s) and address(es) of the owner or developer of the project site and of any consulting firm retained by the applicant together with the name of the applicant’s principal contact at such firm. In addition, the applicant shall pay a $250 filing fee at the time of submittal.
(D) Each application shall include a statement that any land clearing, construction, or development involving the movement of earth shall be in accordance with the post-construction runoff control plan and that a trained individual shall be on the project site on all days when construction or grading activity takes place.
(E) The City of Southport will review each application for a site development permit to determine its conformance with the provisions of this chapter. Within 45 days after receiving an application, the City shall, in writing:
(1) Approve the erosion and sediment control plan and post-construction runoff control plan and issue a site development permit prior to the initiation of any land clearing activities;
(2) Approve the erosion and sediment control plan and post-construction runoff control plan subject to such reasonable conditions as may be necessary to secure substantially the objectives of this regulation, and issue the permit subject to these conditions; or
(3) Disapprove the erosion and sediment control plan and post-construction runoff control plan, indicating the reason(s) and procedure for submitting a revised application and/or submission.
(F) Failure of the City to act on an original or revised application within 45 days of receipt shall authorize the applicant to proceed in accordance with the plans as filed unless such time is extended by agreement between the applicant and the City. Pending preparation and approval of a revised plan, development activities shall be allowed to proceed in accordance with conditions established by the City’s stormwater quality management plan.
(G) The sufficiency of the construction plans shall be based upon Rule 5 regulations, the City’s stormwater quality management plan, the State of Indiana Storm Water Quality Manual, and the City of Indianapolis Storm Water Design and Construction Specifications Manual.
(H) After receiving approval, if revisions to the construction plans require a change in measures appropriate to control the quality or quantity of stormwater runoff, then revised plans must be submitted to the City.
(I) The applicant will be required to file with the City a performance bond, letter of credit, or other improvement security in the amount deemed sufficient by the City to cover all costs of improvements, landscaping, and maintenance of improvements for such period as specified by the City, and engineering and inspection costs to cover the cost of failure to repair of improvements installed on the project site.
(J) The performance bond will require periodic renewal since it must cover the perpetual maintenance and care of the permanent post-construction runoff control structure or system in place. The applicant will notify the City of the impending performance bond expiration and the issuance of a renewed performance bond.
(K) The project site owner must submit a notice of termination (NOT) letter to the City when all land-disturbing activities have been completed, the entire project site has been stabilized, and all temporary erosion and sediment control measures have been removed. (Ord. 5.09, passed 2-19-2007)
5.12.050 DESIGN REQUIREMENTS.
Unless judged by the City to be exempt or granted a waiver, the following performance criteria shall be addressed for stormwater management at all sites:
(A) All site designs shall establish stormwater management practices to control the peak flow rates of stormwater discharge associated with specified design storms and reduce the generation of stormwater. These practices should seek to utilize pervious areas for stormwater treatment and to infiltrate stormwater runoff from driveways, sidewalks, rooftops, parking lots, and landscaped areas to the maximum extent practical to provide treatment for both water quality and quantity.
(B) Annual groundwater recharge rates shall be maintained, by promoting infiltration through the use of structural and nonstructural methods.
(C) Post-construction best management practices (BMPs) are installed after construction has been completed and the site has been stabilized. Installing certain BMPs, such as bioretention areas and sand filters, prior to stabilization can cause failure of the measure due to clogging from sediment. With a strict construction sequence, however, detention ponds and other BMPs can be installed initially during construction and used as permanent runoff control measures upon completion of construction activities. In those instances, the construction sequence must require that the pond is cleaned out with pertinent elevations and storage and treatment capacities reestablished as noted in the approved post-construction runoff control plan.
(D) The City has adopted a policy that the control of stormwater runoff quality will be based on the management of total suspended solids. For new development, BMPs shall be designed to remove 80% of the average annual post-developmental total suspended solids (TSS). It is presumed that a BMP complies with this performance standard if it is:
(1) Sized to capture the prescribed water quality volume (WQv);
(2) Designed according to the specified performance criteria outlined in the City of Indianapolis Storm Water Design and Construction Specifications Manual;
(3) Constructed properly; and
(4) Maintained regularly.
(E) In addition to TSS removal, BMPs must also be designed to treat the water quality volume (WQv), or the first flush of runoff. All new development projects requiring post-construction runoff control plans shall be required to treat the WQv. Redevelopment projects will be required to obtain stormwater quality approval if the redevelopment activity disturbs more than one acre. Please refer to the City of Indianapolis Storm Water Design and Construction Specifications Manual for further details regarding calculation of the WQv.
(F) The BMPs in Table 5.12.050.1 are acceptable for use in the City if designed, constructed, and maintained according to the criteria set forth in the City of Indianapolis Storm Water Design and Construction Specifications Manual. It is presumed that these acceptable BMPs achieve a target TSS removal rate of 80% when correctly constructed and maintained.
(G) Should the developer/project site owner choose to implement a stormwater control device, method, or system not listed as one of the acceptable BMPs for the City, the developer/project site owner must provide proof that the stormwater control device, method, or system can achieve the target TSS removal rate of 80% when correctly constructed.
|
BMP Type |
Description |
Quality Control |
WQv and 80% TSS Removal |
|---|---|---|---|
|
Stormwater Ponds: Wet pond, wet extended detention pond, micropool extended pond, multiple pond systems |
Stormwater retention ponds are constructed stormwater retention basins with a permanent pool (or micropool) of water. Runoff from each rain event is captured and treated in the pool. |
Yes |
Yes |
|
Stormwater Wetlands: Shallow wetland, extended detention wetland, pond/wetland systems, pocket wetland |
Stormwater wetlands are constructed, artificial wetland systems used for stormwater management. They consist of a combination of shallow marsh areas, open water, and semi-wet areas above the permanent pool. |
Yes |
Yes |
|
Bioretention Areas |
Bioretention areas are shallow stormwater basins or landscaped areas that utilize engineered soils and vegetation to capture and treat stormwater runoff. |
No |
Yes |
|
Sand Filters: Surface sand filter, perimeter sand filter |
Sand filters are multi-chamber structures designed to treat stormwater runoff through filtration, using a sand bed as the primary filter media. |
No |
Yes |
|
Water Quality Swales: Dry swale |
Water quality swales are vegetated open channels that are designed and constructed to capture and treat stormwater runoff within dry cells. |
No |
Yes |
|
Biofilters: Filter strip, grass channel |
While biofilters provide some filtering of stormwater runoff, by themselves they cannot meet the 80% TSS removal goal. These measures can only be used as pretreatment measures or as part of a treatment train. |
No |
No |
|
Catch Basin Inserts: Various designs |
Catch basin inserts are small filtering devices installed in each catch basin to trap suspended solids and other pollutants. |
No |
Yes |
(Ord. 5.09, passed 2-19-2007)
5.12.060 INSPECTION.
(A) Each BMP on a site must have an operations and maintenance plan that is submitted with the post-construction runoff control plan and approved by the City. The approved operations and maintenance plan must be provided to the BMP owner.
(B) Annual inspections of permanent BMPs will be performed by the City. Prior to post-construction runoff control plan approval, the developer or owner of a site must pay a predetermined fee to cover the City’s costs for annual inspection for the first three years. After the first three years, the City will annually inspect the facility and bill the owner. Refer to the schedule of fees below.
|
Inspections for first 3 years, paid lump sum in year 1 |
$400 per BMP |
|
Filing fee and plan review |
$250 |
(C) Routine inspections are the responsibility of the BMP owner. Maintenance is also the responsibility of the owner. Maintenance plans and inspection forms for each type of acceptable BMP are provided in the City of Indianapolis Storm Water Design and Construction Specifications Manual and should be used as guidance for performing maintenance activities. Completed routine inspection forms must be maintained by the BMP owner and produced upon request by the City.
(D) In the event that the City finds a BMP in need of maintenance or repair, the City will notify the BMP owner of the necessary maintenance or repairs and give the landowner a timeframe for completing the maintenance or repairs. If the maintenance or repairs are not completed within the designated timeframe, the City shall perform the repairs or maintenance and bill the landowner for the actual costs of the work.
(E) The City must be notified of any changes in BMP ownership, major repairs, or BMP failure in writing within 30 days. (Ord. 5.09, passed 2-19-2007)
5.12.070 ENFORCEMENT.
(A) Stop-work order (revocation of permit). In the event that any person holding a site development permit pursuant to this chapter violates the terms of the permit or implements site development in such a manner as to materially adversely affect the health, welfare, or safety of persons residing or working in the neighborhood or development site so as to be materially detrimental to the public welfare or injurious to property or improvements in the neighborhood, the City may issue a stop-work order and may suspend or evoke the site development permit.
(B) Violation and penalties. No person shall construct, enlarge, alter, repair, or maintain any grading, excavation, or fill, or cause the same to be done, contrary to or in violation of any terms of this chapter. Any person violating any of the provisions of this chapter shall be responsible for such chapter violation and each day during which any violation of any of the provisions of this chapter is committed, continued, or permitted shall constitute a separate offense. Upon conviction of any such violation, such person, partnership, or corporation shall be punished by a fine of not more than $2,500 for each offense. In addition to any other penalty authorized by this section, any person, partnership, or corporation convicted of violating any of the provisions of this chapter shall be required to bear the expense of such restoration. (Ord. 5.09, passed 2-19-2007)