In compliance with this Chapter, a stormwater management plan shall be submitted to the City Engineer for review. The stormwater management plan shall describe how the quantity and quality of stormwater will be managed after construction is complete for every discharge from the site and/or into a water resource. The plan will illustrate the type, location, and dimensions of every structural and non-structural stormwater management practice incorporated into the site design, and the rationale for their selection. The rationale must address how these stormwater management practices will address flooding within the site as well as flooding that may be caused by the development upstream and downstream of the site. The rationale will also describe how the stormwater management practices minimize impacts to the physical, chemical, and biological characteristics of on-site and downstream water resources and, if necessary, correct current degradation of water resources that is occurring or take measures to prevent predictable degradation of water resources.
The stormwater management plan shall consist of:
(a) A brief narrative section, including stormwater run-off calculations. The narrative section shall include the following:
(1) Project Description: Briefly describe the nature and types of land- disturbing activity. Note, specifically, those items not self-evident from the plan drawings.
(2) Existing Site Conditions: To include topography, vegetation, and on-site drainage, consistent with information in TR-55, or other acceptable stormwater model calculations, for both pre-development and post- development run-off.
(3) Stormwater run-off: Include estimations and calculations for both pre- development and post-development peak discharge, using the TR-55 method. Include the calculation of the runoff coefficients for both the pre- and post-construction site conditions. Include critical storm determinations and demonstrate how the run-off from upper watershed areas has been considered in these calculations. (There is no requirement to detain water from offsite.)
(4) Provisions for long-term operation and maintenance of permanent stormwater facilities as described in Section 920.21(c). A copy of the deed restriction should be included on the title page of the construction plans.
(5) Names and addresses: The Professional Engineer responsible and in charge of the plan, the property owner, and the operator having responsibility for the overall development area.
(6) Areas of Jurisdictional Waters: If applicable to the site a copy of any U. S. Army Corps of Engineers permits must be submitted, showing project approval, along with any restrictions that apply to site activities.
(7) The location and name of the immediate receiving stream or surface water(s) and the first subsequent receiving water(s) and the aerial extent and description of wetlands and other special aquatic sites at or near the site which will be disturbed or which will receive discharges from disturbed areas of the project. For discharges to a municipal separate storm sewer system (MS4), the point of discharge to the MS4 and the location where the MS4 ultimately discharges to a water resource shall be indicated.
(8) List TMDLs applicable for the site and demonstrate that appropriate BMPs or stormwater control measures (SCMs have been selected to address these TMDLs).
(9) Ohio EPA Notice of Intent: If applicable to site, a copy of the NOI or NPDES permit number issued for the project. Contact the Ohio EPA for additional information, and/or for permit applications.
(b) Construction plan sheets, containing drainage, erosion/sediment control measures (per SWP3 requirements), and any other details that may be useful to the contractor. It is recommended that BMP's be incorporated into construction drawings, details, and in general notes to contractors. Site construction plans, drawings and details shall, at a minimum, contain:
(1) Vicinity map indicating the site, in relation to the surrounding area.
(2) Construction plan sheets with a maximum scale of one-inch equals 50 feet (1" = 50'), existing topography, using one-foot (1') intervals. Two-foot (2') contour intervals may be acceptable if approved by the City Engineer. Specifically, include location of springs, lakes, wetlands, etc., within 200 feet of site. In addition, all plans shall be referenced to Ohio State Plane Coordinate System North.
(3) Grading plan, showing limits of clearing and grading, areas of excavation, or other earth-disturbing activity, and final contours. Soil types, and relevant boundaries, shall also be included on this sheet.
(4) Existing and proposed drainage patterns, including watershed lines, sub- areas, direction(s) of flow, and watershed acreage.
(5) Description of prior land uses at the site.
(6) The location and name of immediate water resource(s) and the first subsequent water resource(s) and a description of water resource(s) that will be disturbed, or will receive discharge(s) from the site, along with a general description of the condition of those water resources and any existing stream crossings or other in-stream activities.
(7) Soil Types for the entire site, including locations of highly erodible soils.
(8) Existing and proposed locations of buildings, roads, parking facilities, utilities, etc.
(9) A site survey performed by a Registered Professional Surveyor to establish boundary lines, and the location of all access, maintenance, or other easements on the property.
(10) Location of BMP and stormwater control structures to be used. Include details and directions for installation in the contractor's notes. All structures should be drawn to scale, showing the area contributing to the drainage.
(11) Location and elevation of proposed structures shall be indicated in all developments.
(12) Detail drawings, indicating structural practices that will be used, especially ones not referenced in the City of Mount Vernon Standards.
(13) Permanent stormwater control facilities will require the following information to be included on approved construction plans:
A. Location and size of all structure, including detail drawings, and maintenance requirements during and after construction.
B. Final site conditions including stormwater inlets and permanent nonstructural and structural stormwater management practices. Details of stormwater management practices shall be drawn to scale and shall indicate volumes and sizes of contributing drainage areas.
C. Any other structural and/or non-structural stormwater management practices necessary to meet the design criteria in this regulation and any supplemental information requested by the City Engineer. Developers shall provide as-built plan data, pursuant to Section 920.29(b), to document the condition of the facility, prior to final inspection of any new development.
(14) Certification of Professional Engineer. Certification required by a Registered Professional Engineer in the State of Ohio.
(15) Specific Contractor Notes. Two notes, in particular, should be placed on the plan, to meet NPDES requirements: Sediment ponds, and perimeter controls, shall be implemented as the first step of grading, and installed within seven (7) calendar days from the start of grubbing. These measures shall continue to function until all disturbed areas are re-stabilized. Observe, also, disturbed areas that will remain not worked for a period of twenty-one (21) calendar days, or longer, unless an extension is granted by the City Engineer, shall be stabilized with seeding and mulching, or by other appropriate means, as soon as possible, but not to exceed seven (7) calendar days after earth-moving activity ceases.
(16) Review and Filing Fee. The submitted stormwater management plan and SWP3 will not receive a final review and approval for permit from the City Engineer, until the appropriate fees have been paid by the developer pursuant to Section 920.33.
(17) Calculations: The applicant shall submit calculations for projected stormwater runoff flows, volumes, and timing into and through all stormwater management practices for flood control, channel protection, water quality, and the condition of the habitat, stability, and incision of each water resource and it's the floodplain. These submittals shall be completed for both pre- and post-development land use conditions and shall include the underlying assumptions and hydrologic and hydraulic methods and parameters used for these calculations. The applicant shall also include critical storm determination as described in Section 920.19(c) and demonstrate that the runoff from upper watershed areas have been considered in the calculations.
(18) Existing and proposed drainage patterns: The location and description of existing and proposed drainage patterns and stormwater management practices, including any related stormwater management practices beyond the development area and the larger common development area.
(c) Operations and Maintenance Agreement. An Operations and Maintenance Agreement is required for stormwater management practices under this regulation and shall be a standalone document between the City of Mount Vernon and the owner. The City engineer will provide the applicant with guidance language for this document. A copy of this agreement should be attached to the property deed. The agreement shall contain the following information and provisions:
(1) Identification of the landowner(s), organization or municipality responsible for long-term operation and maintenance, including repairs of SCMs.
(2) The landowner(s), organization, or municipality shall maintain SCMs in accordance with this regulation.
(3) The City Engineer has the authority to enter upon the property to conduct inspections as necessary, with prior notification of the property owner, to verify that the SCMs are being maintained and operated in accordance with this regulation.
(4) The City shall maintain public records of the results of site inspections, shall inform landowner(s), organization, or municipality responsible for maintenance of the inspection results, and shall specifically indicate in writing any corrective actions required to bring the SCMs into proper working condition.
(5) If the City Engineer notifies the landowner(s), organization, or municipality responsible for maintenance of the maintenance problems that require correction, the specific corrective actions shall be taken within a reasonable time as determined by the City Engineer.
(6) The City is authorized to enter upon the property and perform the corrective actions identified in the inspection report if the landowner(s), organization or municipality responsible for maintenance does not make the required corrections in the specified time period. The City shall be reimbursed by the landowner(s), organization or municipality responsible for maintenance for all expenses incurred within ten (10) days of receipt of invoice from the City, or more with written approval from the City Engineer.
(7) The method of funding long-term maintenance and inspection of all SCMs.
(8) A release of the City from all damages, accidents, or casualties, occurrences or claims that might arise or be asserted against the City from the construction, presence, existence, or maintenance of the SCMs. .
(d) Inspection and Maintenance Plan. This plan will be developed by the applicant and reviewed by the City. Once the Inspection and Maintenance Plan is approved, a recorded copy of the Plan must be submitted to the City Engineer as part of the final inspection approval. The plan will include at a minimum:
(1) The location of each SCM and identification of the drainage area served by each SCM.
(2) Photographs of each SCM, including all inlets and outlets upon completion of construction.
(3) Schedule of inspection.
(4) A schedule for regular maintenance for each aspect of the stormwater management system and description of routine and non-routine maintenance tasks to ensure continued performance of the system as is detailed in the approved Stormwater Management Plan. A maintenance inspection checklist written so the average person can understand it shall be incorporated. The maintenance plan will include a detailed drawing of each SCM and outlet structures with the parts of the outlet structure labeled. This schedule may include additional standards, as required by the City Engineer, to ensure continued performance of SCMs permitted to be located in or within fifty (50) feet of water resources.
(5) The location and documentation of all access and maintenance easements on the property.
Alteration or termination of these stipulations is prohibited. The applicant must provide a draft of this Operations and Maintenance Agreement as part of the stormwater management plan application. Once a draft is approved, a recorded copy of this Agreement must be submitted to the City to receive final inspection approval of the site.
(Ord. 2019-35. Passed 11-12-19.)