(a)   The purpose of this regulation is to establish technically feasible and economically reasonable storm water management standards to achieve a level of storm water quality and quantity control that will minimize damage to property and degradation of water resources and will promote and maintain the health, safety, and welfare of the residents of the Village of Walton Hills.

   (b)   This regulation requires owners who develop or re-develop their property within the Village to:

      (1)   Control storm water runoff from their property and ensure that all storm water management practices are properly designed, constructed and maintained.

      (2)   Reduce water quality impacts to receiving water resources that may be caused by new development or redevelopment activities.

      (3)   Control the volume, rate, and quality of storm water runoff originating from their property so that surface water and ground water are protected and flooding and erosion potential are not increased.

      (4)   Minimize the need to construct, repair, and replace subsurface storm drain systems.

      (5)   Preserve natural infiltration and ground water recharge, and maintain subsurface flow that replenishes water resources, except in slippage-prone soils.

      (6)   Incorporate storm water quality and quantity controls into site planning and design at the earliest possible stage in the development process.

      (7)   Reduce the expense of remedial projects needed to address problems caused by inadequate storm water management.

      (8)   Maximize use of storm water management practices that serve multiple purposes including, but not limited to, flood control, erosion control, fire protection, water quality protection, recreation, and habitat preservation.

      (9)   Design sites to minimize the number of stream crossings and the width of associated disturbance in order to minimize the Village's future expenses related to the maintenance and repair of stream crossings.

      (10)   Maintain, promote, and re-establish conditions necessary for naturally occurring stream processes that assimilate pollutants, attenuate flood flows, and provide a healthy water resource.

   (c)   This regulation shall apply to all parcels used or being developed, either wholly or partially, for new or relocated projects involving highways and roads; subdivisions or larger common plans of development; industrial, commercial, institutional, or residential projects; building activities on farms; redevelopment activities; grading; and all other uses that are not specifically exempted in this Section 1289.01.

   (d)   Public entities, including the State of Ohio, Cuyahoga County, and the Village of Walton Hills shall comply with this regulation for roadway projects initiated after March 10, 2006 and, to the maximum extent practicable, for projects initiated before that time.

   (e)   This regulation does not apply to activities regulated by, and in compliance with, the Ohio Agricultural Sediment Pollution Abatement Rules.

   (f)   This regulation does not require a Comprehensive Storm Water Management Plan for linear construction projects, such as pipeline or utility line installation, that do not result in the installation of impervious surface as determined by the Village Engineer. Such projects must be designed to minimize the number of stream crossings and the width of disturbance. Linear construction projects must comply with the requirements of Chapter 1290, Erosion and Sediment Control.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

   The definitions contained in Ohio Environmental Protection Agency ("Ohio EPA")'s Construction General Permit entitled "Authorization for Storm Water Discharges Associated with Construction Activity under the National Pollutant Discharge Elimination System" and Ohio EPA's Municipal Separate Storm Sewer (MS4) Permit entitled "Authorization for Small Municipal Separate Storm Sewer Systems to Discharge Stormwater Under the National Pollutant Discharge Elimination System" in effect at the time a permit is applied for under this chapter shall apply to this chapter and the following definitions shall also apply:

   (a)   “Acre.” A measurement of area equaling 43,560 square feet.

   (b)   “As-built survey.” A survey shown on a plan or drawing prepared by a registered surveyor indicating the actual dimensions, elevations, and locations of any structures, underground utilities, swales, detention facilities, and sewage treatment facilities after construction has been completed.

   (c)   “Best management practices (BMPs).” Schedule of activities, prohibitions of practices, operation and maintenance procedures, treatment requirements, and other practices to reduce the pollution of water resources and to control storm water volume and rate.

   (d)   “Clean water act.” Pub. L. 92-500, as amended Pub. L. 95-217, Pub. L. 95-576, Pub. L. 96-483, Pub. L. 97-117, and Pub. L. 100-4, 33 U.S.C. 1251 et seq. Referred to as the Federal Water Pollution Control Act or the Federal Water Pollution Control Act Amendments of 1972.

   (e)   “Community.” The Village of Walton Hills, its designated representatives, boards, or commissions.

   (f)   “Comprehensive Storm Water Management Plan.” The written document and plans meeting the requirements of this regulation that sets forth the plans and practices to minimize storm water runoff from a development area, to safely convey or temporarily store and release post-development runoff at an allowable rate to minimize flooding and stream bank erosion, and to protect or improve storm water quality and stream channels.

   (g)   “Construction General Permit.” The most recent General National Pollutant Discharge Elimination System (NPDES) permit for authorization of stormwater discharges associated with construction activities issued by Ohio EPA (Ohio EPA Permit #OHC000005 and its successors).

   (h)   “Critical storm.” A storm that is calculated by means of the percentage increase in volume of runoff by a proposed development area. The critical storm is used to calculate the maximum allowable storm water discharge rate from a developed site.

   (i)   “Detention facility.” A basin, pond, oversized pipe, or other structure that reduces the peak flow rate of storm water leaving the facility by temporarily storing a portion of the storm water entering the facility.

   (j)   “Development area.” A parcel or contiguous parcels owned by one person or persons, or operated as one development unit, and used or being developed for commercial, industrial, residential, institutional, or other construction or alteration that changes runoff characteristics.

   (k)   “Development drainage area.” A combination of each hydraulically unique watershed with individual outlet points on the development area.

   (l)   “Disturbed area.” An area of land subject to erosion due to the removal of vegetative cover and/or soil-disturbing activities.

   (m)   “Drainage.” The removal of excess surface water or ground water from land by surface or subsurface drains.

   (n)   “Erosion.” The process by which the land surface is worn away by the action of wind, water, ice, gravity, or any combination of those forces.

   (o)   “Extended conveyance.” A storm water management practice that replaces and/or enhances traditional open or closed storm drainage conduits by retarding flow, promoting percolation of runoff into the soil, and filtering pollutants during the storm water quality event.

   (p)   “Extended detention.” A storm water management practice that replaces and/or enhances traditional detention facilities by releasing the runoff collected during the storm water quality event over at least 24 to 48 hours, retarding flow and allowing pollutants to settle within the facility.

   (q)   “Final stabilization.” All soil-disturbing activities at the site have been completed and a uniform perennial vegetative cover with a density of at least 80% coverage for the area has been established or equivalent stabilization practices, such as the use of mulches or geotextiles, have been employed.

   (r)   “Grading.” The process in which the topography of the land is altered to a new slope.

   (s)   “Hydrologic unit code.” A cataloging system developed by the United States Geological Survey and the Natural Resource Conservation Service to identify watersheds in the United States.

   (t)   “Impervious cover.” Any surface that cannot effectively absorb or infiltrate water. This may include roads, streets, parking lots, rooftops, sidewalks, and other areas not covered by vegetation.

   (u)   “Infiltration.” A storm water management practice that does not discharge to a water resource during the storm water quality event, requiring collected runoff to either infiltrate into the ground water and/or be consumed by evapotranspiration, thereby retaining storm water pollutants in the facility.

   (v)   “Larger common plan of development.” A contiguous area where multiple separate and distinct construction activities may be taking place at different times on different schedules under one plan.

   (w)   “Maximum extent practicable.” The level of pollutant reduction that operators of small municipal separate storm sewer systems regulated under 40 C.F.R. Parts 9, 122, 123, and 124, referred to as NPDES Storm Water Phase II, must meet.

   (x)   “NPDES.” National Pollutant Discharge Elimination System. A regulatory program in the Federal Clean Water Act that prohibits the discharge of pollutants into surface waters of the United States without a permit.

   (y)   “Non-structural storm water management practice.” Storm water runoff control and treatment techniques that use natural practices to control runoff and/or reduce pollution levels.

   (z)   “Post-development.” The conditions that exist following the completion of soil- disturbing activity in terms of topography, vegetation, land use, and the rate, volume, quality, or direction of storm water runoff.

   (aa)   “Pre-construction meeting.” Meeting prior to construction between all parties associated with the construction of the project, including government agencies, contractors and owners, to review agency requirements and plans as approved and submitted.

   (bb)   “Pre-development.” The conditions that exist prior to the initiation of soil- disturbing activity in terms of topography, vegetation, land use, and the rate, volume, quality, or direction of storm water runoff.

   (cc)   “Professional engineer.” A professional engineer registered in the State of Ohio with specific education and experience in water resources engineering, acting in conformance with the Code of Ethics of the Ohio State Board of Registration for Engineers and Surveyors.

   (dd)   “Rainwater and Land Development Manual.” Ohio's standards for storm water management, land development, and urban stream protection. The most current edition of these standards shall be used with this regulation.

   (ee)   “Redevelopment.” A construction project on land where impervious cover has previously been developed and where the new land use will not increase the runoff coefficient. If the new land use will increase the runoff coefficient, then the project is considered to be a new development project rather than a redevelopment project. (Refer to Table 1 in Section 1289.09)

   (ff)   “Riparian and wetland setback.” The real property adjacent to a water resource on which soil-disturbing activities are limited, all as defined by Chapter 1294.

   (gg)   “Riparian area.” Land adjacent to any brook, creek, river, or stream having a defined bed and bank that, if appropriately sized, helps to stabilize streambanks, limit erosion, reduce flood size flows, and/or filter and settle out runoff pollutants, or performs other functions consistent with the purposes of this regulation.

   (hh)   “Runoff.” The portion of rainfall, melted snow, or irrigation water that flows across the ground surface and is eventually returned to water resources.

   (ii)   “Sediment.” The soils or other surface materials that can be transported or deposited by the action of wind, water, ice, or gravity as a product of erosion.

   (jj)   “Sedimentation.” The deposition of sediment in water resources.

   (kk)   “Site owner/operator.” Any individual, corporation, firm, trust, commission, board, public or private partnership, joint venture, agency, unincorporated association, municipal corporation, county or state agency, the Federal government, other legal entity, or an agent thereof that is responsible for the overall construction site.

   (ll)   “Soil-disturbing activity.” Clearing, grading, excavating, filling, or other alteration of the earth's surface where natural or human-made ground cover is destroyed, and that may result in, or contribute to, increased storm water quantity and/or decreased storm water quality.

   (mm)   “Stabilization.” The use of best management practices that reduce or prevent soil erosion by storm water runoff, trench dewatering, wind, ice, gravity, or a combination thereof.

   (nn)   “Stormwater control measure (SCM).” A structure or area designed to remove pollutants from stormwater and/or reduce stormwater flow rates. SCM's are a subset of Best Management Practices (BMP's) as defined in the Construction General Permit.

   (oo)   “Structural storm water management practice.” Any constructed facility, structure, or device that provides storage, conveyance, and/or treatment of storm water runoff.

   (pp)   “Surface waters of the State.” All streams, lakes, reservoirs, marshes, wetlands, or other waterways situated wholly or partly within the boundaries of the State, except those private waters which do not combine or affect a junction with surface water. Waters defined as sewerage systems, treatment works or disposal systems in Ohio R.C. 6111.01 are not included.

   (qq)   “Total maximum daily load.” The sum of the existing and/or projected point source, non-point source, and background loads for a pollutant to a specified watershed, water body, or water body segment. A TMDL sets and allocates the maximum amount of a pollutant that may be introduced into the water and still ensures attainment and maintenance of water quality standards.

   (ss)   “Water resource.” Any public or private body of water; including wetlands; the area within the ordinary high water level of lakes and ponds; as well as the area within the ordinary high water level of any brook, creek, river, or stream having a defined bed and bank (either natural or artificial) which confines and conducts continuous or intermittent flow.

   (tt)   “Water resource crossing.” Any bridge, box, arch, culvert, truss, or other type of structure intended to convey people, animals, vehicles, or materials from one side of a watercourse to another. This does not include private, noncommercial footbridges or pole- mounted aerial electric or telecommunication lines, nor does it include below-grade utility lines.

   (uu)   “Watershed.” The total drainage area contributing storm water runoff to a single point.

   (vv)   “Wetland.” Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions, including swamps, marshes, bogs, and similar areas (40 CFR 232, as amended).

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13; Ord. 2022-11. Passed 11-15-22.)

   (a)   Compliance with the provisions of this regulation shall not relieve any person from responsibility for damage to any person otherwise imposed by law. The provisions of this regulation are promulgated to promote the health, safety, and welfare of the public and are not designed for the benefit of any individual or any particular parcel of property.

   (b)   By approving a Comprehensive Storm Water Management Plan under this regulation, the Village does not accept responsibility for the design, installation, and operation and maintenance of storm water management practices.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

   (a)   Where this regulation is in conflict with other provisions of law or ordinance or requirements in the Construction General Permit, the most restrictive provisions, as determined by the Village Engineer, shall prevail.

   (b)   If any clause, section, or provision of this regulation is declared invalid or unconstitutional by a court of competent jurisdiction, the validity of the remainder shall not be affected thereby.

   (c)   This regulation shall not be construed as authorizing any person to maintain a nuisance on their property, and compliance with the provisions of this regulation shall not be a defense in any action to abate such a nuisance.

   (d)   Failure of the Village to observe or recognize hazardous or unsightly conditions or to recommend corrective measures shall not relieve the site owner from the responsibility for the condition or damage resulting therefrom, and shall not result in the Village, its officers, employees, or agents being responsible for any condition or damage resulting therefrom.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13; Ord. 2022-11. Passed 11-15-22.)

   (a)   This regulation requires that a Comprehensive Storm Water Management Plan be developed and implemented for soil-disturbing activities disturbing one or more acres of total land, or less than one acre if part of a larger common plan of development or sale disturbing one or more acres of total land, and on which any regulated activity of Section 1289.01(c) is proposed.

   (b)   The Village shall administer this regulation, shall be responsible for determination of compliance with this regulation, and shall issue notices and orders as may be necessary. The Village may consult with the Cuyahoga SWCD, private engineers, storm water districts, or other technical experts in reviewing the Comprehensive Storm Water Management Plan.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

   (b)   Preliminary Comprehensive Storm Water Management Plan. The applicant shall submit two sets of a Preliminary Comprehensive Storm Water Management Plan (Preliminary Plan) and the applicable fees to the Village Engineer. The Preliminary Plan shall show the proposed property boundaries, setbacks, dedicated open space, public roads, water resources, storm water control facilities, and easements in sufficient detail and engineering analysis to allow the Village Engineer to determine if the site is laid out in a manner that meets the intent of this regulation and if the proposed storm water management practices are capable of controlling runoff from the site in compliance with this regulation. The applicant shall submit two sets of the Preliminary Plan and applicable fees as follows:

      (1)   For subdivisions: In conjunction with the submission of the preliminary subdivision plan.

      (2)   For other construction projects: In conjunction with the application for a zoning permit.

      (3)   For general clearing projects: In conjunction with the application for a zoning permit.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13; Ord. 2022-11. Passed 11-15-

   Approvals issued in accordance with this regulation do not relieve the applicant of responsibility for obtaining all other necessary permits and/or approvals from other Federal, State, and/or County agencies. If requirements vary, the most restrictive shall prevail. These permits may include, but are not limited to, those listed below. Applicants are required to show proof of compliance with these regulations before the Village will issue a building or zoning permit.

   (a)   Ohio EPA NPDES Permits Authorizing Storm Water Discharges Associated with Construction Activity or the Most Current Version Thereof. Proof of compliance with these requirements shall be the applicant's Notice of Intent (NOI) number from Ohio EPA, a copy of the Ohio EPA Director's Authorization Letter for the NPDES Permit, or a letter from the site owner certifying and explaining why the NPDES Permit is not applicable.

      (1)   A letter from the site owner certifying that a qualified professional has surveyed the site and determined that Section 404 of the Clean Water Act is not applicable.

      (2)   A site plan showing that any proposed fill of waters of the United States conforms to the general and special conditions specified in the applicable Nationwide Permit. Wetlands, and other waters of the United States, shall be delineated by protocols accepted by the U.S. Army Corps of Engineers at the time of application of this regulation.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

      (1)   Site description:

         A.   A description of the nature and type of the construction activity (e.g. residential, shopping mall, highway, etc.).

         B.   Total area of the site and the area of the site that is expected to be disturbed (i.e. grubbing, clearing, excavation, filling or grading, including off-site borrow areas).

         C.   A description of prior land uses at the site.

         D.   An estimate of the impervious area and percent of imperviousness created by the soil-disturbing activity at the beginning and at the conclusion of the project.

         E.   Existing data describing the soils throughout the site, including the soil series and association, hydrologic soil group, porosity, infiltration characteristics, depth to ground water, depth to bedrock, and any impermeable layers.

         F.   If available, the quality of any known pollutant discharge from the site such as that which may result from previous contamination caused by prior land uses.

         G.   The location and name of the immediate water resource(s) and the first subsequent water resource(s).

         H.   The aerial (plan view) extent and description of water resources at or near the site that will be disturbed or will receive discharges from the project.

         I.   Describe the current condition of water resources including the vertical stability of stream channels and indications of channel incision that may be responsible for current or future sources of high sediment loading or loss of channel stability.

      (2)   Site map showing:

         A.   Limits of soil-disturbing activity on the site.

         B.   Soils types for the entire site, including locations of unstable or highly erodible soils.

         C.   Existing and proposed one-foot contours. This must include a delineation of drainage watersheds expected before, during, and after major grading activities as well as the size of each drainage watershed in acres.

         D.   Water resource locations including springs, wetlands, streams, lakes, water wells, and associated setbacks on or within 200 feet of the site, including the boundaries of wetlands or streams and first subsequent named receiving water(s) the applicant intends to fill or relocate for which the applicant is seeking approval from the U.S. Army Corps of Engineers and/or Ohio EPA.

         E.   Existing and planned locations of buildings, roads, parking facilities, and utilities.

         F.   The location of any in-stream activities including stream crossings.

      (3)   Contact information: Company name and contact information as well as contact name, addresses, and phone numbers for the following:

         A.   The professional engineer who prepared the Comprehensive Storm Water Management Plan.

         B.   The site owner.

      (4)   Phase, if applicable, of the overall development plan.

      (5)   List of sublot numbers if project is a subdivision.

      (6)   Ohio EPA NPDES Permit Number and other applicable state and federal permit numbers, if available, or status of various permitting requirements if final approvals have not been received.

      (7)   Location, including complete site address and sublot number if applicable.

      (8)   Location of any easements or other restrictions placed on the use of the property.

      (9)   A site plan sheet showing:

         A.   The location of each proposed post-construction storm water management practice.

         B.   The geographic coordinates of the site and each proposed practice in North American Datum Ohio State Plan North.

         It is preferred that the entire site be shown on one plan sheet to allow a complete view of the site during plan review. If a smaller scale is used to accomplish this, separate sheets providing an enlarged view of areas on individual sheets should also be provided.

      (10)   An Inspection and Maintenance Agreement. The Inspection and Maintenance Agreement required for storm water management practices under this regulation shall be a stand alone document between the Village and the applicant and shall contain the following information and provisions:

         A.   The location of each storm water management practice, including those practices permitted to be located in, or within 50 feet of, water resources, and identification of the drainage area served by each storm water management practice.

         B.   A schedule for regular maintenance for each aspect of the storm water management system and description of routine and non-routine maintenance tasks to ensure continued performance of the system as is detailed in the approved Comprehensive Storm Water Management Plan. This schedule may include additional standards, as required by the Village Engineer, to ensure continued performance of storm water management practices permitted to be located in, or within 50 feet of, water resources.

         C.   The location and documentation of all access and maintenance easements on the property.

         D.   Identification of the landowner(s), organization, or municipality responsible for long-term maintenance, including repairs, of the storm water management practices.

         E.   The landowner(s), organization, or municipality shall maintain storm water management practices in accordance with this chapter.

         F.   The Village has the authority to enter upon the property to conduct inspections as necessary to verify that the storm water management practices are being maintained and operated in accordance with this chapter.

         G.   The Village shall maintain public records of the results of site inspections, shall inform the landowner(s), organization, or municipality responsible for maintenance of the inspection results, and shall specifically indicate any corrective actions required to bring the storm water practices into proper working condition.

         H.   If the Village 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 frame as determined by the Village.

         I.   The Village is authorized to enter upon the property and to 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 Village shall be reimbursed by the landowner(s), organization, or municipality responsible for maintenance for all expenses incurred within ten days of receipt of invoice from the Village.

         J.   The method of funding long-term maintenance and inspections of all storm water management practices.

         K.   A release of the Village from all damages, accidents, casualties, occurrences, or claims that might arise or be asserted against the Village from the construction, presence, existence, or maintenance of the storm water management practices.

         Alteration or termination of these stipulations is prohibited. The applicant must provide a draft of this Inspection and Maintenance Agreement as part of the Comprehensive Storm Water Management Plan submittal. Once a draft is approved, a recorded copy of the Agreement must be submitted to the Village to receive final inspection approval of the site.

      (11)   Inspection and maintenance plan: This plan will meet the requirements of the Construction General Permit and will be developed by the applicant and reviewed by the Village Engineer. Maintenance requirements of each SCM during and after construction should be included. Once the inspection and maintenance plan is approved, a recorded copy of the plan must be provided to the property owner or association that will be responsible for long-term operation and maintenance of the BMP and submitted to the Village Engineer as part of the final inspections.

      (12)   Calculations required: The applicant shall submit calculations for projected storm water runoff flows, volumes, and timing into and through all storm water management practices for flood control, channel protection, water quality, and the condition of the habitat, stability, and incision of each water resource and its the floodplain, as required in Section 1289.09 of this regulation. 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 and demonstrate that the runoff from upper watershed areas have been considered in the calculations.

      (13)   List of all contractors and subcontractors before construction: Prior to construction or before the pre-construction meeting, provide the list of all contractors and subcontractors names, addresses, and phones involved with the implementation of the Comprehensive Storm Water Management Plan, including a written document containing signatures of all parties as proof of acknowledgment that they have reviewed and understand the requirements and responsibilities of the Comprehensive Storm Water Management Plan. 

      (14)   Existing and proposed drainage patterns: The location and description of existing and proposed drainage patterns and storm water management practices, including any related storm water management practices beyond the development area and the larger common development area.

      (15)   For each storm water management practice to be employed on the development area, include the following:

         A.   Location and size, including detail drawings, maintenance requirements during and after construction, and design calculations, all where applicable.

         B.   Final site conditions including storm water inlets and permanent nonstructural and structural storm water management practices. Details of storm water management practices shall be drawn to scale and shall show volumes and sizes of contributing drainage areas.

         C.   Any other structural and/or non-structural storm water management practices necessary to meet the design criteria in this regulation and any supplemental information requested by the Village Engineer.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13; Ord. 2022-11. Passed 11-15-22.)

         A.   The storm water management practices shall function as an integrated system that controls flooding and minimizes the degradation of the physical, biological, and chemical integrity of the water resources receiving storm water discharges from the site. Acceptable practices shall:

            1.   Not disturb riparian areas, unless the disturbance is intended to support a watercourse restoration project and complies with Chapter 1291.

            2.   Maintain pre-development hydrology and ground water recharge on as much of the site as practicable.

            3.   Only install new impervious surfaces and compact soils where necessary to support the future land use.

            4.   Compensate for increased runoff volumes caused by new impervious surfaces and soil compaction by reducing storm water peak flows to less than predevelopment levels.

         B.   Storm water management practices that meet the criteria in this regulation, and additional criteria required by the Village Engineer, shall comply with this regulation.

         If the applicant proposes to discharge to natural wetlands, a hydrological analysis shall be preformed to demonstrate that the proposed discharge matches the pre- development hydroperiods and hydrodynamics.

      (3)   Sheet flow. The site shall be graded in a manner that maintains sheet flow over as large an area as possible. The maximum area of sheet flow shall be determined based on the slope, the uniformity of site grading, and the use of easements or other legally-binding mechanisms that prohibit re-grading and/or the placement of structures within sheet flow areas. In no case shall the sheet flow length be longer than 300 feet, nor shall a sheet flow area exceed 1.5 acres. Flow shall be directed into an open channel, storm sewer, or other storm water management practice from areas too long and/or too large to maintain sheet flow, all as determined by the Village Engineer.

         A.   Storm sewers shall be designed such that they do not surcharge from runoff caused by the 5-year, 24-hour storm, and that the hydraulic grade line of the storm sewer stays below the gutter flow line of the overlying roadway, or below the top of drainage structures outside the roadway during a 10-year, 24-hour storm. The system shall be designed to meet these requirements when conveying the flows from the contributory area within the proposed development and existing flows from offsite areas that are upstream from the development.

         B.   The minimum inside diameter of pipe to be used in public storm sewer systems is 12 inches. Smaller pipe sizes may be used in private systems, subject to the approval of the Village Engineer.

         C.   All storm sewer systems shall be designed taking into consideration the tailwater of the receiving facility or water resource. The tailwater elevation used shall be based on the design storm frequency. The hydraulic grade line for the storm sewer system shall be computed with consideration for the energy losses associated with entrance into and exit from the system, friction through the system, and turbulence in the individual manholes, catch basins, and junctions within the system.

         D.   The inverts of all curb inlets, manholes, yard inlets, and other structures shall be formed and channelized to minimize the incidence of quiescent standing water where mosquitoes may breed.

         E.   Headwalls shall be required at all storm sewer inlets or outlets to and from open channels or lakes.

         A.   Water resource crossings other than bridges shall be designed to convey the stream's flow for the minimum 25-year, 24-hour storm.

         B.   Bridges, open bottom arch or spans are the preferred crossing technique and shall be considered in the planning phase of the development. Bridges and open spans should be considered for all State Scenic Rivers, cold water habitat, exceptional warm water habitat, seasonal salmonid habitat streams, and Class III headwater streams. The footers or piers for these bridges and open spans shall not be constructed below the ordinary high water mark.

         C.   If a culvert or other closed bottom crossing is used, 25% of the cross-sectional area or a minimum of one foot of box culverts and pipe arches must be embedded below the channel bed.

         D.   The minimum inside diameter of pipes to be used for crossings shall be 12 inches.

         E.   The maximum slope allowable shall be a slope that produces a 10 fps velocity within the culvert barrel under design flow conditions. Erosion protection and/or energy dissipaters shall be required to properly control entrance and outlet velocities.

         F.   All culvert installations shall be designed with consideration for the tailwater of the receiving facility or water resource. The tailwater elevation used shall be based on the design storm frequency.

         G.   Headwalls shall be required at all culvert inlets or outlets to and from open channels or lakes.

         H.   Streams with a drainage area of five square miles or larger shall incorporate floodplain culverts at the bankfull elevation to restrict head loss differences across the crossing so as to cause no rise in the 100-year storm event.

         I.   Bridges shall be designed such that the hydraulic profile through a bridge shall be below the bottom chord of the bridge for either the 100-year, 24-hour storm, or the 100-year flood elevation as determined by FEMA, whichever is more restrictive.

      (8)   Compensatory flood storage mitigation. In order to preserve floodplain storage volumes and thereby avoid increases in water surface elevations, any filling within floodplains approved by the Village must be compensated by removing an equivalent volume of material. First consideration for the location(s) of compensatory floodplain volumes should be given to areas where the stream channel will have immediate access to the new floodplain within the limits of the development site. Consideration will also be given to enlarging existing or proposed retention basins to compensate for floodplain fill if justified by a hydraulic analysis of the contributing watershed. Unless otherwise permitted by the Village, reductions in volume due to floodplain fills must be mitigated within the legal boundaries of the development. Embankment slopes used in compensatory storage areas must reasonably conform to the natural slopes adjacent to the disturbed area. The use of vertical retaining structures is specifically prohibited.

      (1)   The peak discharge rate of runoff from the critical storm and all more frequent storms occurring under post-development conditions shall not exceed the peak discharge rate of runoff from a 1-year, 24-hour storm occurring on the same development drainage area under pre-development conditions.

      (2)   Storms of less frequent occurrence (longer return periods) than the critical storm, up to the 100-year, 24-hour storm shall have peak runoff discharge rates no greater than the peak runoff rates from equivalent size storms under pre-development conditions. The 1, 2, 5, 10, 25, 50, and 100-year storms shall be considered in designing a facility to meet this requirement.

      (3)   The critical storm for each specific development drainage area shall be determined as follows:

         A.   Determine, using a curve number-based hydrologic method that generates hydrographs, or other hydrologic method approved by the Village Engineer, the total volume (acre-feet) of runoff from a 1-year, 24-hour storm occurring on the development drainage area before and after development. These calculations shall meet the following standards:

            1.   Calculations shall include the lot coverage assumptions used for full build out as proposed.

            2.   Calculations shall be based on the entire contributing watershed to the development area.

            3.   Curve numbers for the pre-development condition must reflect the average type of land use over the past ten years and not only the current land use.

            4.   To account for future post-construction improvements to the site, calculations shall assume an impervious surface such as asphalt or concrete for all parking areas and driveways, regardless of the surface proposed in the site description.

         B.   From the volume determined in Section 1289.09(d)(3)A., determine the percent increase in volume of runoff due to development. Using the percentage, select the 24-hour critical storm from Table 1.

 

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13; Ord. 2022-11. Passed 11-15-22.)

   When the Village of Walton Hills determines that site constraints compromise the intent of this regulation, off-site alternatives may be used that result in an improvement of water quality and a reduction of water quantity. Such alternatives shall meet the standards in the Construction General Permit and shall achieve the same level of stormwater quantity control that would be achieved by the onsite controls required under this regulation. The Village Engineer may require proof of Ohio EPA review and approval for any alternative action proposed.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13; Ord. 2022-11. Passed 11-15-22.)

   Access to storm water management practices as required by the Village Engineer for inspections and maintenance shall be secured by easements. The following conditions shall apply to all easements:

   (a)   Easements shall be included in the Inspection and Maintenance Agreement submitted with the Comprehensive Storm Water Management Plan.

   (b)   Easements shall be approved by the Village prior to approval of a final plat and shall be recorded with the Cuyahoga County Auditor and on all property deeds.

   (c)   Unless otherwise required by the Village Engineer, access easements between a public right-of-way and all storm water management practices shall be no less than 25 feet wide. The easement shall also incorporate the entire practice plus an additional 25-foot-wide band around the perimeter of the storm water management practice.

   (d)   The easement shall be graded and/or stabilized as necessary to allow maintenance equipment to access and manipulate around and within each facility, as defined in the Inspection and Maintenance Agreement for the site.

   (e)   Easements to structural storm water management practices shall be restricted against the construction therein of buildings, fences, walls, and other structures that may obstruct the free flow of storm water and the passage of inspectors and maintenance equipment; and against the changing of final grade from that described by the final grading plan approved by the Village. Any re-grading and/or obstruction placed within a maintenance easement may be removed by the Village at the property owners' expense.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

   To receive final inspection and acceptance of any project, or portion thereof, the following must be completed and provided to the Village Engineer:

   (a)   Final stabilization must be achieved and all permanent storm water management practices must be installed and made functional, as determined by the Village Engineer and per the approved Comprehensive Storm Water Management Plan.

   (b)   An as-built certification, including a survey and inspection, must be sealed, signed and dated by a professional engineer and a professional surveyor with a statement certifying that the storm water management practices, as designed and installed, meet the requirements of the Comprehensive Storm Water Management Plan approved by the Village Engineer. In evaluating this certification, the Village Engineer may require the submission of a new set of storm water practice calculations if he or she determines that the design was altered significantly from the approved Comprehensive Storm Water Management Plan. The as-built survey must provide the location, dimensions, and bearing of such practices and include the entity responsible for long- term maintenance as detailed in the Inspection and Maintenance Agreement.

   (c)   A copy of the complete and recorded Inspection and Maintenance Agreement as specified in Section 1289.08 must be provided to the Village Engineer.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

   The Village shall inspect storm water management practices periodically. Upon finding a malfunction or other need for maintenance, the Village shall provide written notification to the responsible party, as detailed in the Inspection and Maintenance Agreement, of the need for maintenance. Upon notification, the responsible party shall have five working days, or other mutually agreed upon time, to makes repairs or submit a plan with detailed action items and established timelines. Should repairs not be made within this time, or a plan approved by the Village Engineer for these repairs not be in place, the Village may undertake the necessary repairs and assess the responsible party.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

   The Comprehensive Storm Water Management Plan review, filing, and inspection fee is part of a complete submittal and is required to be submitted to the Village before the review process begins. The Village Engineer shall establish a fee schedule based upon the actual estimated cost for providing these services.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

   (a)   If a Comprehensive Storm Water Management Plan is required by this regulation, soil-disturbing activities shall not be permitted until a cash bond of 5% of the total project cost, has been deposited with the Village Finance Department. This bond shall be posted for the Village to perform the obligations otherwise to be performed by the owner of the development area as stated in this regulation and to allow all work to be performed as needed in the event that the applicant fails to comply with the provisions of this regulation. The storm water bond will be returned, less Village administrative fees, when the following three criteria are met:

      (1)   After 80% of the lots of the project have been complete or 100% of the total project has been permanently stabilized or three years from the time of permanent stabilization have passed.

      (2)   An as built inspection of all water quality practices is conducted by the Village Engineer.

      (3)   An Inspection and Maintenance Agreement signed by the developer, the contractor, the Village, and the private owner or homeowners association who will take long- term responsibility for these BMPs, is accepted by the Village Engineer.

   (b)   Once these criteria are met, the applicant shall be reimbursed all bond monies that were not used for any part of the project. If all of these criteria are not met after three years of permanent stabilization of the site, the Village may use the bond monies to fix any outstanding issues with all storm water management structures on the site and the remainder of the bond shall be given to the private lot owner/homeowners association for the purpose of long term maintenance of the project.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

   The applicant may not direct runoff through any water quality structures or portions thereof that would be degraded by construction site sediment until the entire area tributary to the structure has reached final stabilization as determined by the Village Engineer. This occurs after the completion of the final grade at the site, after all of the utilities are installed, and the site is subsequently stabilized with vegetation or other appropriate methods. The developer must provide documentation acceptable to the Village Engineer to demonstrate that the site is completely stabilized. Upon this proof of compliance, the water quality structure(s) may be completed and placed into service. Upon completion of installation of these practices, all disturbed areas and/or exposed soils caused by the installation of these practices must be stabilized within two days.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

   No person shall violate or cause or knowingly permit to be violated any of the provisions of this regulation, or fail to comply with any of such provisions or with any lawful requirements of any public authority made pursuant to this regulation, or knowingly use or cause or permit the use of any lands in violation of this regulation or in violation of any permit granted under this regulation.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

   Any person aggrieved by any order, requirement, determination, or any other action or inaction by the Village in relation to this regulation may appeal to the Court of Common Pleas. Such an appeal shall be made in conformity with Ohio R.C. Chapters 2505 and 2506. Written notice of appeal shall be served on the Village.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13.)

   (a)   Any person, firm, entity or corporation; including but not limited to, the owner of the property, his agents and assigns, occupant, property manager, and any contractor or subcontractor who violates or fails to comply with any provision of this regulation shall be subject to Section 202.99 Penalties of the Village of Walton Hills Codified Ordinances. A separate offense shall be deemed committed each day during or on which a violation or noncompliance occurs or continues.

   (b)   The imposition of any other penalties provided herein shall not preclude the Village instituting an appropriate action or proceeding in a court of proper jurisdiction to prevent an unlawful development, or to restrain, correct, or abate a violation, or to require compliance with the provisions of this regulation or other applicable laws, ordinances, rules, or regulations, or the orders of the Village.

(Ord. 2010-34. Passed 12-14-10; Ord. 2013-24. Passed 12-17-13; Ord. 2017-5. Passed 3-21-17.)