A. Purpose
The purpose of these stormwater drainage standards is to provide adequate facilities to accommodate stormwater runoff created by a development project either through on-site or off-site improvements or alterations to the drainage system.
B. Site Grading and Drainage Development Plans; Waivers.
1. Any person or persons proposing to develop or redevelop land shall design and implement a site grading and drainage development plan which will:
a. Yield quantities of surface water runoff from the development site at rates which are the same as or less than those before development occurred and result in rates of gross erosion as specified in this section.
b. Not result in increasing current potentials for sedimentation of lands, siltation of waters and flooding of watercourses that are at lower elevations off-site.
c. Meet or exceed requirements promulgated by state and federal agencies to promote positive drainage practices, mitigate damage to water quality and foster beneficial environmental practices. (Ord. 17-14)
2. No changes subject to regulation under this chapter shall be made in the existing natural surface composition or subsurface configuration of any land proposed for development or redevelopment within the City without prior written approval of a site development plan by the Approving Agent. Approval of a site development plan required according to Section 9.35, H shall not be given:
a. Unless a determination is made by the Approving Agent that implementation of an approved site grading and drainage development plan would not cause runoff, erosion and sediment impacts that would be harmful or damaging to the lands and waters off-site; or
b. Until a plan for minimizing the harmful and damaging potentials of runoff, erosion and sediment impacts anticipated resulting from the implementation of a proposed site grading and drainage development plan has been approved by the Approving Agent.
3. Development situations may exist such that the development will have none of the harmful effects associated with increased runoff rates and volumes or sediment disposition. Such developments are eligible for a waiver from these standards; however, the waiver applies only to the following requirements and may have specific conditions attached by the Approving Agent, including, but not limited to:
a. The preparation of plans, maps and/or information specified in Section 9.35, I.
b. The installation of sediment abatement control devices until such time as site inspection indicates that they may be unnecessary.
c. Controlling runoff to predevelopment conditions as specified in Section 9.35, F except that storm water runoff must be controlled to the maximum volume and minimum rate feasible for the site as determined by the Approving Agent.
4. The request for a waiver shall be in writing and shall include sufficient detail to determine that granting a waiver will not be detrimental to abutting properties or to the drainage system. However, the waiver does not in any way imply a relaxation of any of the other standards in this chapter, including the requirement for adequate on-site drainage, the ability to accept runoff from land tributary to the development or reasonable control of soil erosion and sediment. Development activities for which waivers may be considered include the following:
a. Single-family residential developments involving improvement of an individual lot in a previously approved subdivision.
b. Multifamily residential, commercial or industrial developments which total 2 acres or less.
c. Modifications to, or redevelopment of, an existing development which will not result in additional impervious areas.
5. Development activities that are exempt from this chapter include the following:
a. Additions of less than 250 square feet to existing property, such as driveways, sidewalks, patios, etc.
b. Regular farming procedures on land designed for such use.
C. Storm Sewer and Drainage
1. Drainage Plans
a. Intent - A drainage plan is required.
i. To provide a planned guideline for the construction of the development so that the drainage of the whole development and for each lot in the development meet the requirements of all sections of this chapter; and
ii. So that the drainage of the subject plat will be consistent with the existing or planned drainage of all adjacent plats.
b. General
i. An overall map of the development shall be submitted to the City Engineer for approval prior to any work on the development which would alter or increase the original flow of water.
ii. This map shall show all existing and proposed lots, streets, and utilities in the proposed plat and existing lots, streets, and utilities immediately adjacent to the proposed plat.
iii. This map shall show the general drainage plan proposed for the development. A detailed drainage plan for each lot or group of lots shall be formulated when the type of structures to be placed on the lots is determined. The final plan shall include all storm sewers, drains, swales, appurtenances for the development.
iv. Drainage shall be indicated on each plot plan submitted for a building permit and must conform to the overall drainage plan for the development. Plot plans shall indicate the FFE and the adjacent building grade. The plot plan shall show the approximate elevations of the lot corners, final grade. Swales, if any, with the direction of the flow of storm water, shall be indicated. Contour lines may be used to show this final drainage plan.
v. Plot plans shall include solutions to any unusual problems, such as springs, swamps, ponds, etc., when they are known to exist, either on the proposed development or on adjacent land, if the subject development or lot will be affected.
vi. The drawing showing the proposed overall drainage plan shall contain a statement to the effect that the proposal presented does not interfere with the drainage of adjacent properties.
vii. The covenants on the record plan shall contain a statement to the effect that succeeding owners of portions of the plat shall not erect any structures or change the grading in any manner which would alter the water flow from or to adjacent land unless written permission is obtained from the owners of such adjacent land.
2. Storm Water Disposal
a. All areas shall be sloped to a lower elevation off the lots or to drainage structures on the lot in accordance with the site grading plan. Two or more lots may be considered as one area. Business, industrial and commercial areas may be considered as one lot for storm water disposal purposes.
b. Unpaved drainage swales shall have adequate width and depth to carry the runoff.
c. Longitudinal gradients for swales or gutters shall be provided as follows:
i. For centerlines within 15 feet of buildings, or in a required outdoor area, see Section 9.35(D)(4).
ii. For center lines in other lot areas, see Section 9.35(D)(9)(a).
d. The permanence and maintenance of off-site drainage ways shall be assured by locating such drainage ways in public or private rights of way or easements, as shown on the record plan.
e. Where drain inlets or catch basins are installed, emergency surface drainage overflow shall be provided to prevent possible flooding against or within the building in the event of the failure of the underground drainage structures.
3. Drain Lines
a. Storm sewers shall be constructed of concrete pipe in the public right-of-way. Pipe not in the public right-of-way may be constructed with alternate materials as permitted in the Ohio Department of Transportation Construction and Material Specifications. (Ord. 17-14, 7-18)
b. Drain lines shall be of adequate size and gradient to provide proper run-off and shall be at such depth as to preclude damage to the pipe.
c. Drain lines for surface drainage shall be sealed where necessary to prevent harmful infiltration of sand, muck and other materials. For subsurface drainage, perforated or porous pipe shall be backfilled with gravel or crushed rock over the pipe to a point at least 6 inches below finished grade.
4. Drain Inlets
The design, size and construction of drain inlets shall be adequate to carry water imposed without overflow.
5. Drainage Structures
a. Intent. The intent of the requirements in this section is to provide for the collection of surface and subsurface water in order to protect any dwelling or other improvements; and usable lot areas.
b. General
i. Paved gutters, drain lines and inlets or other necessary drainage structures shall be installed where storm water disposal cannot be obtained without their use or where erosion cannot be prevented by finish grading and/or planting. Such drainage structures shall be shown on plat design drawings.
ii. Design, construction and installation of drainage structures shall be in accordance with standard engineering practices and shall be suitable for the use and maintenance contemplated.
iii. Gutters and drain lines shall be connected to suitable outfalls. The permanence and maintenance of off-site drainage ways shall be assured by public or private rights of way, by easements or by other acceptable means.
iv. Splash blocks shall be installed at the bottom of each downspout unless the downspout is connected to a drain line. See Section 9.35, C, 7 for construction details.
6. Paved Gutters
a. Gutters shall be constructed of concrete, brick or other durable material.
b. Gutters shall have an adequate depth, width and longitudinal gradient to carry water without overflow. Gutters shall be connected to an adequate storm sewer system.
c. Gutters shall be installed to provide permanent drainage with reasonable maintenance.
7. Splash Blocks
a. Splash blocks shall be constructed of concrete or other durable material.
b. The minimum width of splash blocks shall be 12 inches. The minimum length shall be 30 inches.
c. Splash blocks shall be firmly imbedded to prevent displacement.
8. Dry Wells
a. Dry wells for the disposal of water from foundation drains and crawl spaces, etc., are permissible only when the bottom of a dry well projects into a strata of porous soil at a level where the bottom of the dry well is above the ground water table at its seasonal height.
b. The minimum distance of dry wells from buildings shall be 20 feet. The separation between dry wells and buildings may be reduced to ten feet if the diameter of the dry well does not exceed three feet.
c. The size and construction of dry wells shall be adequate to dispose of the water.
d. Sump pumps shall be connected to dry wells or to the nearest point of the drainage system of the plat. Sump pumps and other drains which have water flowing more than 50 percent of the time may not discharge into the gutter.
D. Grading
1. Intent - It is the intent of this section to provide grading which shall:
a. Direct water away from buildings;
b. Prevent standing water and soil saturation detrimental to structures and lot uses;
c. Provide for disposal of water from a lot;
d. Preserve such desirable lot features that do not interfere with the proper drainage of the lot or the desired use of the lot;
e. Provide grades for safe and convenient access to and around buildings and lots for their use and maintenance; and
f. Protect adjacent properties from excessive water drainage.
2. General
a. For examples of typical grading design, see illustrations following the text of these regulations.
b. For regulations pertaining to building foundations or concrete floor slabs on fill, see the 2006 Residential Code of Ohio (RCO), and the OBC Commercial Building Code.
3. Protective Slopes Around Buildings
a. The slope of the ground downward away from building foundations to lower areas shall conform to Section 9.35, C, 2.
b. The horizontal width of the downward sloping area away from foundations shall be a minimum of 10 feet, except where restricted by property lines.
c. The vertical fall of protective slopes shall be a minimum of 6 inches in 10 feet. However, the vertical fall at the upper end of a swale may be reduced to 3 inches in 10 feet, provided that a long slope from a nearby high bank does not exist.
4. Minimum Gradient
a. For concrete or other impervious surfaces, the minimum gradient shall be one sixteenth of an inch per foot (one-half of one percent).
b. For pervious surfaces, the minimum gradient in the first 10 feet from the building shall be as provided in Section 9.35, D, 3. Beyond the 10 foot area, the gradient shall comply with the objectives of this chapter.
5. Maximum Gradient
The maximum gradient shall be 2 1/2 inches for the first four feet from all building walls, except where restricted by property lines. The balance of the protective slope shall have a maximum gradient of 2:1 (two feet horizontally to one foot vertically). (See Section 9.35(D)(9)(b)).
6. Usable Outdoor Area (Ord. 17-16)
At minimum, 35% of a single- or two-family residential lot shall be composed of usable outdoor area. The usable outdoor area may be located in any yard(s), but shall be of such location, size and shape as to provide for outdoor living and service functions. Usable outdoor areas may overlap or be part of required protective slopes around buildings. The area may be a single area or several adjacent or separate subareas. The maximum grade for usable areas shall be five (5) percent. Usable area may include any driveway, patio, or other paved surface, but shall not include the footprint of the primary structure. The City Council may waive this requirement in its entirety or on a lot-by-lot basis as part of a Preliminary or Final Development Plan, Preliminary Subdivision or Record Plat.
7. Other Lot Areas.
a. The minimum gradient for other lot areas shall comply with subsection 7 hereof, unless lesser gradients are shown on exhibits accepted by the City prior to any building construction activity, including grading and/or clearing. To be acceptable, the lesser gradient must be adequate to drain the area without having a detrimental effect upon buildings or upon essential lot usage and improvements. Conditions which would result in prolonged standing of water at any season are not acceptable. Where surface water disposal is proposed by infiltration into the ground, technical exhibits, such as soil gradation analyses and/or infiltration tests, may be required.
b. The maximum gradient, unless slopes are to be held by satisfactory existing or planned vegetation, rock outcroppings or brick, rock or concrete walls, shall be limited as follows:
i. If the vertical height of slope is 30 inches or less, the maximum gradient shall be one and one-half feet horizontal to one foot vertical.
ii. For slopes with a vertical height of over 30 inches, the maximum gradient shall be two feet horizontally to one foot vertically.
iii. Slopes of over 1 1/2 feet to 1 foot with only grass planned as the retaining vegetation shall not be permitted.
c. Tops and bottoms of banks at swales, terraces, etc., shall be rounded for convenient maintenance.
8. Rough Grading
a. Preservation of Trees and Shrubs. Natural site assets, such as existing trees, shrubs, ground cover and top soil, shall be preserved and protected whenever practicable, provided that retention of such items does not interfere with the drainage plan of the area.
b. Compliance with Drainage Plans and Plot Plans; Subgrades. The balance of the lot shall be graded to comply with the grading indicated on the drainage plan and the plot plan submitted for a building permit. The subgrade shall be established by cut and fill, approximately parallel to the finish gradients and at an elevation to allow for sod and other installations.
c. Filled Areas
i. Filled areas under and fifteen feet beyond buildings and other structures shall be compacted to meet the requirements of the 2006 Residential Code of Ohio (RCO) One and Two Family Dwelling Code, as adopted in Section of the Building and Housing Code and the OBC, Ohio Commercial Code.
ii. For the balance of the area involved, all surface debris detrimental to lot improvements shall be removed.
iii. Tree stumps eighteen inches below finished grade shall be removed and cut down.
iv. Original ground exceeding a one to three slope shall be scarified and benched if it is to receive fill, in order to prevent slippage of the fill.
v. Fill material shall be reasonably free of debris or other material detrimental to the lot for the first three feet below the finished grade and shall have reasonable moisture content when placed. Fill in the vicinity of future drainage structures shall be compacted to avoid later settling and damage to the structures.
vi. Fills having a depth of over sixty inches shall be constructed in accordance with standard engineering practices.
9. Finish Grading
a. Lot areas shall be finish graded to the extent necessary to make the entire lot comply with the preceding standards of this chapter.
b. The subsoil shall be smoothed parallel to the finished grade elevations and scarified where necessary to secure bond with the surface soil or sod.
c. Where installation of a lawn or planting is required, the surface soil shall be workable, suitable for the support of plant life and free of large stones and other debris detrimental to plant life. For other areas the soil shall be as provided above or shall be soil which the property owner can improve to a comparable quality without difficult or expensive work.
d. Surface soil shall be soil capable of sustaining plant life.
e. Surface soil shall be spread uniformly to provide a smooth even surface.
f. Surface soil shall be compacted lightly to minimize settlement.
E. Erosion Control: Lawns and Ground Cover
1. Intent. Lawns and ground cover shall be provided:
a. To prevent erosion; and
b. Where required, to make yards usable.
2. Required Areas. Appropriate vegetative cover shall be provided for the following areas as follows:
a. On swales, as follows:
i. Where the gradient exceeds five-eighths of an inch per foot, five percent.
ii. Minimum width: 4 feet. (See Section 9.35, Storm water and Drainage Standards)
b. On slopes where the gradient exceeds 4 feet horizontally to one foot vertically.
c. On other areas from the street roadway to a point 15 feet behind the building, or as agreed between the builder and purchaser. Planting in undisturbed areas may be omitted when suitable existing vegetation is present to prevent erosion.
3. Materials
a. Lawn materials and ground cover shall be appropriate for the expected use and suitable to the local climate, soil conditions and exposure.
b. Seed quality shall have a minimum purity of 85 percent, a minimum germination of 80 percent and a weed content not exceeding a maximum of one-half of one percent. The seed mixture shall be not less than 85 percent, by weight, of permanent grass, and 15 percent, by weight, of annual grass.
c. Sod shall be fresh cut, taken from a thick stand of permanent lawn grass, reasonably free from weeds and coarse grass. It shall be at least one and one-half inches thick, totally, uniform in thickness and cut in strips.
4. Installation. Installation of lawns and ground cover shall be as follows:
a. See Section 9.35, D, 11 for finish grading
b. The seed or plant bed shall be prepared by scarifying the surface lightly
c. Seed shall be broadcasted as recommended by the producer, but at a rate of not less than four pounds per 1,000 square feet. The seeded ground shall be rolled with a light roller and watered thoroughly with a fine spray.
d. Sod shall be laid in strips, avoiding wide joints. On slopes, sod laying shall be started at the bottom parallel to the contour of the slope. Sod shall be rolled with a light roller and watered thoroughly.
e. Ground cover shall be planted to provide a dense mat at maturity.
f. Lawns and ground cover shall be installed only during appropriate seasons and favorable weather and with suitable soil conditions.
g. Lawns and ground cover shall be watered, replanted and maintained as necessary until possession is taken by the owner.
Figure 9.8 Lot Grading Plan
F. Storm Water Runoff Control Standards (Ord. 7-18)
1. In general, drainage systems shall be designed according to locally accepted design practices and sound engineerin g judgment and shall conform to the following:
a. Storm sewer design shall be sufficient to convey the design storm discharge with an average recurrence interval of 10 years so that the pipe flowing full condition (hydraulic grade line at the top of the pipe) is not extended. The 25-year storm hydraulic grade line shall not exceed the proposed ground elevation. The 100-year storm shall be contained on-site via an overland flow path through the on-site detention basin.
b. Storm sewer design shall be submitted to the City in ODOT CDSS format, or a pre-approved alternate commercially-available software, for the10-, 25-, and 100-year storms.
c. Lot grading, in-tract drainage and street improvements for all subdivisions shall be designed so that floods having an average recurrence interval of 100 years or less will not cause inundation or damage to any dwellings. A grading plan for each subdivision will be required to define the lot grading and in-tract drainage. All developments within areas of special flood hazard or delineated on the official National Flood Insurance Program Flood Insurance Rate Maps, or as determined by the City, shall comply with FEMA design requirements.
d. All drainage channels, conduits and other structures located outside the road right-of-way designed to convey public storm runoff (off-site runoff) should be contained in suitable public easements. Easements for open channels shall include sufficient area along the channel banks to permit access for maintenance equipment. Open channels may be fenced along both sides through urban areas where it is necessary to protect the public as well as to prevent encroachment upon needed access areas.
2. Areas adjacent to open drainageways and ponds shall be graded to preclude the entrance of storm water, except at planned locations. Where retention/detention areas are located on the project periphery, the developer may be required to provide additional landscaping or screening to adequately protect abutting properties.
3. Each development shall provide for the on-site or off-site detention of excess storm water runoff resulting from that development. For the purpose of this section, "excess storm water runoff" shall include all increases in storm water peak flows and volume resulting from an increase in the impervious surface of the site, including all additions of buildings, roads and parking lots; changes in soil absorption caused by compaction during development; modifications in contours, including the filling or draining of small depression areas, alterations of drainageways or regrading of slopes; destruction of forests; the alteration of drainageways or the installation of collection systems to intercept street flows or to replace swales or other drainageways; or the alteration of subsurface flows, including any groundwater dewatering or diversion practices, such as curtain drains, compared with the site in its natural state.
4. Any foreseeable increase in rates and volume of site surface drainage water runoff caused by site development shall be controlled so that the post-development peak rate of runoff does not exceed that of the predevelopment one-year frequency storm for all twenty-four hour storms between a one-year frequency and the critical storm frequency as determined below. A recommended method which may be used to determine changes in rates and volumes of runoff is presented in the U.S. Department of Agriculture, Engineering Division of the Soil Conservation Service (SCS), Urban Hydrology for Small Watersheds, Technical Release No. 55 (Washington, D.C.: USDA, June, 1986), and the Ohio Supplement (April, 1981). To find the critical storm frequency for which additional control will be needed:
a. The percent increase in runoff volume for a one-year frequency, twenty-four hour storm, shall be determined; and
b. The critical storm frequency for which additional control is needed shall be determined by using the percent increase in runoff volume, derived in paragraph thereof, in the Table 9.12 below:
Table 9.12 Critical Storm Frequency
Percent Increase in Runoff Volume From a One-Year Frequency, 24 Hour Storm | Critical Storm Frequency (yrs.) | |
Equal to or Greater Than: | Less Than:
| |
Percent Increase in Runoff Volume From a One-Year Frequency, 24 Hour Storm | Critical Storm Frequency (yrs.) | |
Equal to or Greater Than: | Less Than:
| |
- | 10 | 1 |
10 | 20 | 2 |
20 | 50 | 5 |
50 | 100 | 10 |
100 | 250 | 25 |
250 | 500 | 50 |
500 | - | 100 |
5. Storms of less frequent occurrence (longer return period) than the critical storm shall have a peak rate of runoff not greater than for the same storm under predevelopment conditions. For example, if the total volume is shown to be increased by thirty-five percent, the critical storm is a five-year storm. The peak rate of runoff for all storms up to this intensity shall be controlled so as not to exceed the peak rate of runoff from a one-year frequency storm under predevelopment conditions in the area. The runoff from a more intense storm need only be controlled so as not to exceed the predevelopment peak rate from the same frequency of storm.
6. The intent of subsections (4) and (5) above will be met if the criteria are fulfilled for the one, two, five, twenty-five, fifty and 100-year storms.
7. All detention facilities and improvements required by this section shall comply with the following regulations:
a. Access easements. An access easement shall be provided to all detention facilities from the nearest public road so that such facilities are accessible in case emergency maintenance work is required. The minimum easement width will be 10 feet.
b. Storage volumes. Storage may be provided by wet or dry bottom basins or reservoirs.
c. Maximum depth. The maximum planned depth of storm water detained shall be 5 feet, unless site conditions lend themselves to greater depths.
d. Outlet control structures. Outlet control structures shall be designed as simply as possible and shall operate automatically. They will be designed to limit discharges into existing or planned downstream channels or conduits so as not to exceed the existing flow from the site in its natural condition or as further controlled in Section 9.35(F)(4).
e. Spillways. Emergency overflow facilities shall be provided unless inflow is controlled to divert flows when the basin is at capacity. The spillway shall safely discharge the detention basin overflow without damage to the detention basin. A minimum of one foot freeboard shall be provided for the 100-year twenty-four hour storm event.
f. Dry bottom basins. For basins designed without permanent pools, the following provisions shall apply:
i. Interior drainage. Provision must be made to facilitate interior drainage, including the provision of natural grades to outlet structures, longitudinal and transverse grades to perimeter drainage facilities or the installation of subsurface drains.
ii. Multipurpose features. These may be designed to serve secondary purposes for recreation, open space or other types of use which will not be adversely affected by occasional or intermittent flooding.
iii. Cleaning. The basins shall be designed for periodic cleaning and removal of sediments, which shall be removed from the site or otherwise disposed of in an appropriate manner.
g. Wet basins. For basins designed with permanent pools, the following provisions shall apply:
i. Depth for fish. If fish are used to help keep the basin clean, at least one-quarter of the area of the permanent pool must have a minimum depth of ten feet.
ii. Facilities for emptying. For emergency purposes, cleaning or shoreline maintenance, facilities shall be provided or plans prepared for the use of auxiliary equipment to permit emptying and drainage.
iii. Pollution abatement. Aeration facilities may be required when the quality of the influent and detention time would result in a lowering of dissolved oxygen content in the basin.
iv. Slopes. Approach slopes shall be at least six to one, but not more than three to one, and shall be at least four to six feet wide and slope gently toward the basin. The side slopes shall be of non-erosive material with a slope of one to one or flatter. The ledge shall be four to six feet wide and slope gently toward the shore to prevent people or objects from sliding into deep water. There shall be a freeboard of twelve to eighteen inches above the high-water elevation on all retention basins. Alternative designs for side slopes may be considered under special circumstances where good engineering practice is demonstrated.
v. Cleaning. The basins shall be designed to include sediment traps in all inlets. Sediment traps shall be designed to permit periodic cleaning and maintenance. A basin maintenance plan shall be developed to insure that the design depths of the basin will remain over time.
Figure 9.9 Lot Stormwater Drainage Plan
h. Building regulations.
i. Parking lot storage. Paved parking lots may be designed to provide temporary detention storage of storm water on a portion of their surfaces. Outlets shall be designed to empty the stored waters slowly, and depths of storage must be limited so as to prevent damage to parked vehicles, and storage areas shall be posted with warning signs.
ii. Detention storage. All or a portion of the detention storage may also be provided in underground detention facilities, provided that they meet the design regulations of Section 9.35, F, 7, b and c.
iii. Off-site easements. Off-site easements for storm water management facilities will be required when either of the following conditions exists:
1) The discharge is into any man-made facility for which the City does not have either a drainage easement or right-of-way.
2) The discharge is into a natural system such that the rate or character (i.e. sheet flow versus concentrated flow) of the flow at the property line has been changed. The easement will be required to a point at which natural conditions are duplicated.
iv. Design criteria for off-site drainage. Off-site areas which drain to or across a site proposed for development must be accommodated in the storm water management plans for the development. The storm water management system for the development must be capable of transporting existing off-site flows through or around the development without increasing stages or flows upstream or downstream of the development. The estimation of the off-site flows must be done separately from the estimation of on-site pre- and post-development flows (i.e. separate off-site and on-site hydrographs must be computed due to the typically significant differences in land use characteristics).
v. Alternatives to detention or retention ponds. For sites containing less than 10,000 square feet of total impervious surface, alternatives to detention or retention ponds that utilize landscaped buffers and swale drainage as a means of attenuating the rate of runoff are encouraged, provided that it can be shown that applicable design and performance criteria are met.
vi. Protection of detention and retention facilities from erosion. Measures shall be taken to protect the embankment of detention and retention facilities from erosion and provide a definitive protective flow path downstream of the facility.
G. Off-Site Drainage Facilities
1. The City may allow or require surface water runoff to be discharged into drainage facilities off the site of development if all of the following conditions are met:
a. The drainage facilities are constructed and maintained in accordance with the requirements of this chapter.
b. Adequate provision is made for acquisition, construction and operating costs of the off-site drainage facilities.
c. A request to use these drainage facilities and all information relating to these proposed drainage facilities is made a part of the developer's application.
2. The City may allow or require payment of a fee for redevelopment activities in lieu of constructing a detention or retention facility as specified in Section 9.35, F. Payment received in lieu of redevelopment detention or retention shall be used for storm water improvement projects, including the establishment of regional detention systems. The fee shall be based on an amount per square foot of impervious surface (on-site).
3. Whenever deemed practical, necessary and in the public interest, the City may acquire land and construct these drainage facilities, and, to the greatest extent possible, the fees and charges for such facilities shall be sufficient to cover all costs associated therewith and such facilities shall be self-supporting.
H. Soil Erosion and Sedimentation Control Plan
1. In order to prevent both soil erosion and sedimentation, a soil erosion and sedimentation control plan shall be required whenever a development will involve any clearing, grading, transporting or other form of disturbing the land by the movement of earth. The requirements promulgated by the Ohio Environmental Protection Agency (OEPA) in Permit No. OHC000004 (or most recent revision) are to be satisfied in a Stormwater and Pollution Prevention Plan (SWPPP). (Ord. 17-14)
2. Sediment deposition caused by accelerated storm water runoff over a development site or by accelerated erosion due to the sloughing or sliding of surface soil that has been exposed by grading, dumping, stockpiling or any other excavation-related earth disturbances shall be retarded and confined to within the boundaries of the development site.
3. The accumulative monthly predicted amounts of gross soil loss anticipated from sheet and rill erosion shall be abated to within an average annual rate of fifteen tons per acre during the first year, ten tons per acre for any year thereafter of site development activities and to within five tons per acre per year after site development is completed. The Universal Soil Loss Equation, as referenced in the U.S. Department of Agriculture, Soil Conservation Service (SCS), Water Management and Sediment Control for Urbanizing Areas, (Washington, D.C.: U.S. Government Printing Office, June, 1978), or other approved methods, shall be used to predict average annual rates of gross soil loss by month from a development site.
4. Specifically, the following protection shall be provided for all disturbed areas: minimize velocities of water runoff, maximize protection of disturbed areas from storm water runoff and retain sedimentation within the development site as early as possible following disturbances. A list of major problem areas for erosion and sedimentation control follows. For each one, the purpose of requiring control is described. Soil erosion and sedimentation control measures for all such areas shall be provided with a view toward achieving the specific purpose listed below for which a control plan is required:
a. Erodible slopes: prevent detachment and transportation of soil particles from such slopes.
b. Streams, streambeds, streambanks, bodies of water, lake shorelines: prevent detachment and transportation of soil particles.
c. Drainageways: prevent detachment and transportation of soil particles (which would otherwise deposit in streams, bodies of water or wetlands); promote deposit of sediment loads (traversing these areas) before they reach bodies of water.
d. Land adjacent to streams, ponds, lakes and wetlands: prevent detachment and transportation of soil particles.
e. Enclosed drainage structures: prevent sedimentation in a structure, erosion at the outfall of the system and the deposit of sediment loads within the system or beyond it.
f. Large flat surface areas (unpaved): prevent detachment of soil particles and their off-site transportation.
g. Pervious surfaces: prevent the detachment and transportation of soil (in response to an increase in the rate and/or volume of runoff of the site or its concentration caused by impervious surfaces).
h. Borrow and stockpile areas: divert runoff from the face of slopes which are exposed in the excavation process; convey runoff in stabilized channels to stable disposal points; and leave borrow areas and stockpiles in stable condition.
i. Adjacent properties: prevent their erosion and/or the deposit thereon of sediment.
I. Runoff Control and Sediment Abatement Plans
1. Any person seeking approval of a development proposal shall:
a. Submit a SWPPP per the requirements and recommendations of the OEPA Permit No. OHC000004 (or most recent revision) and the Rainwater Development Manual; (Ord. 17-14)
b. Provide mapped information about the location and vicinity of the area proposed for development;
c. Furnish the following three types of information and maps about the proposed land development and site location:
i. An existing characteristics inventory;
ii. A predevelopment conditions assessment; and
iii. An abatement control plan.
d. Minor additions to existing facilities may be exempted from this requirement by the City Engineer.
2. Specifically, all proposed land developments shall have plans or maps of an appropriate scale that depict existing and proposed improvements, including, but not limited to:
a. Structures, streets, sidewalks, driveways, parking lots, storm drainage systems and appurtenances, utilities, poles, etc.
b. Elevations, contour lines, inverts of sewers and drainage facilities, etc.
c. The location of the boundary of the 100-year flood plain.
3. Runoff control and sediment abatement plan content requirements shall be as follows:
a. A runoff control and sediment abatement plan shall identify how accelerated surface water runoff, increased erosion and sediment deposition induced by site development are to be controlled to within the abatement standards set forth in Section 9.35, F and Section 9.35, H. The developer's engineer shall include in the construction plans a master drainage map showing all existing and proposed features. The map is to be prepared on a twenty-four inch by thirty-six inch sheet on a scale not to exceed one inch equals 100 feet. Listed below are the features that are to be included on the drainage map:
i. Drainage boundaries, including all areas draining to the proposed subdivision or development.
ii. Sufficient topographical information with elevations to verify the location of all ridges, streams, etc.
iii. High water data on existing structures upstream and downstream for the subdivision.
iv. Notes indicating sources of high water data.
v. Notes pertaining to existing standing water areas of heavy seepage, springs, wetlands, streams, etc.
vi. Existing drainage features (ditches, roadways, ponds, etc.). Existing drainage features are to be shown a minimum of 1,000 feet downstream of the proposed development unless the ultimate outfall system is a lesser distance.
vii. Subdivision layouts with horizontal and vertical controls, showing proposed structures with minimum pad elevations.
viii. Proposed drainage features, including locations of inlets, swales, open drainageways, ponding areas, storm sewers, culverts, etc.
ix. Delineation of drainage sub-areas.
x. Retention/detention areas and ingress/egress areas for retention/detention facilities.
xi. The general type of soils (obtained from the soil survey of Montgomery or Greene County).
xii. Ten, twenty-five and 100-year flood elevations for any areas in or within 100 feet of the property. The source of these elevations shall also be shown on the plans.
xiii. A description of current ground cover and/or land use.
b. All proposed drainage features and runoff controls are to be designed in accordance with methods and techniques set forth in the City's Design Manual.
c. A runoff control and sediment abatement plan shall be comprised of, but not limited to, the following information:
i. A map rendered on the base which indicates the number, types, dimensions and locations of all runoff, erosion or sediment control devices to be utilized either temporarily or permanently on a development site;
ii. All pertinent computations made to arrive at the final dimensions of each control device, along with plan and section view drawings of the same rendered at an appropriate design scale to be agreed upon between the applicant and the City Engineer; and
iii. Schedules detailing the timing for the installation and maintenance of each control device.
d. The runoff control and sediment abatement plan shall be prepared by or under the direct supervision of a registered civil engineer.
e. The applicant is to develop and comply with a maintenance plan that: (Ord. 17-14)
i. Designates an entity for stormwater inspection and maintenance responsibilities;
ii. Describes the routine and non-routine maintenance tasks to be undertaken;
iii. Puts forth a schedule for inspection and maintenance;
iv. Specifies any necessary legal binding maintenance easements and agreements;
v. Includes a map showing all access and maintenance easements; and
vi. Specifies that pollutants collected within structural post-construction practices be disposed of in accordance with local, state, and federal regulations.
J. Liabilities and Responsibilities; Enforcement; Privately Owned Installations.
1. Performance Liability. No provision of this chapter shall limit, increase or otherwise affect the liabilities of the permitted or impose any liability upon the City not otherwise imposed by law.
2. Responsibilities of Permitee during Site Development. During site development, a permitee is responsible for:
a. Carrying out all provisions according to approved plans and as required by this chapter;
b. Promptly removing all soil, miscellaneous debris or other materials that may become spilled, dumped or otherwise deposited on any public thoroughfares;
c. Taking precautions to inhibit the deposition of sediment into any sewer system or natural watercourse; and
d. Providing a bond (cash or performance) for sweeping of public streets within the vicinity of the site development in an amount determined by the City Engineer. (Ord. 17-16)
3. Inspections; Enforcement; Stop-Work Order.
a. The developer's engineer shall be required to inspect all drainage facilities under construction and certify their compliance with approved plans, and, in addition, the City may inspect all drainage facilities while under construction. When facilities are not constructed according to approved plans, the City has the explicit authority to compel compliance and require correction of any situations which are not according to the approved plans.
b. Site development operations shall be subject to inspections by the City to determine whether a site development plan is being implemented in compliance with the provisions of this chapter and any plan approval conditions. The applicant shall arrange with the Building Inspection Department for the scheduling of inspections to ensure effective control of erosion and sedimentation and to ensure that all drainage facilities are being completed in accordance to the approved storm water management plan. Prior to final inspection, the developer's engineer shall provide as-built plans of the detention facilities and outlet control structures, documenting facilities that are constructed substantially in accordance with approved plans.
c. After each inspection the inspector shall complete a site development status report. If the inspector finds that operations are being conducted by a permittee in violation of an approved plan or provisions of this chapter, a stop-work order may be issued at that time.
4. Privately Owned Installations.
a. Design, Inspection and Maintenance. Permanent runoff control and sediment abatement installations which are to be privately owned and maintained by an individual or group of property owners shall be:
i. Designed and constructed by the permittee with easements sufficient to allow adequate access for inspections, maintenance and corrective actions, if necessary, by the City.
ii. Inspected as needed by the City to ensure that privately-owned installations are being properly maintained. If not, the City may compel the owners to make the necessary repairs at the expense of the owner.
iii. Maintained as installed by the permitted according to the approved design and not altered unless such alteration is approved by the City.
b. Legal/Operation Entity Requirements.
i. Acceptable entities. The City considers the following entities acceptable to operate and maintain runoff and sediment control facilities:
1) The City; and
2) Non-profit corporations, including homeowners' associations, property owners' associations, condominium owners' associations or master associations.
ii. The property owner or developer is normally not acceptable as a responsible entity, especially when the property is to be sold to various third parties. However, the property owner or developer may be acceptable under one of the following circumstances:
1) The property is wholly owned by said property owner or developer and is intended to be so retained. This would apply to a farm, corporate office or single industrial facility for example.
2) The ownership of the property is retained by the owner or developer and is either leased to third parties, such as in some shopping centers, or rented to third parties, such as in some mobile home parks for example. To satisfy this requirement, the owner or developer must provide written documentation.
iii. Association requirements.
1) If a homeowners' or property owners' association or master application is proposed, the developer must submit the articles of incorporation for the association and the declaration of protective covenants or deed restrictions, as well as a reference map if such is referred to in the documents. After these are approved, the developer must furnish the certificate of incorporation and the recording information (official book and page number) for the declaration.
2) If a condominium association is proposed, the developer must supply the articles of incorporation for the condominium association and the declaration of condominium. After the documents are approved by the City, including stormwater management plan, it will be necessary for the developer to forward a copy of the letter from the County Recorder's Office stating that the documents are proper for filing. The association, be it either a non-profit association or a condominium association, must comply with the applicable provisions of State law.
3) The association must have the following general powers which are reflected in the articles of incorporation:
a. Own and convey property.
b. Operate and maintain common property, specifically the surface water management system as permitted by the City, including all lakes, retention areas, culverts and related appurtenances.
c. Establish rules and regulations.
d. Assess members and enforce said assessments.
e. Sue and be sued.
f. Contract for services (if the association contemplates employing a maintenance company) to provide the services for operation and maintenance.
g. Have as members all the homeowners, lot owners, property owners or unit owners.
h. Exist in perpetuity. However, if the association is dissolved, the articles of incorporation must provide that the property consisting of the surface water management system shall be conveyed to an appropriate agency of local government. If it is not accepted, then the surface water management system must be dedicated to a similar non-profit corporation.
i. All other powers necessary for the purposes for which the association is organized.
iv. The declaration of protective covenants, deed restrictions or declaration of condominium must set forth the following:
1) That it is the responsibility of the association to operate and maintain the surface water management system.
2) That the surface water management system is owned by the association or described therein as common property.
3) That there is a method of assessing and collecting the assessment for the operation and maintenance of the surface water management system.
4) That any amendment which would affect the surface water management system, including the water management portions of the common areas, must have the prior approval of the City.
5) That the declaration of protective covenants be in effect for at least twenty-five years with automatic renewal periods thereafter.
v. If the documents are not submitted with the original application, they must be submitted and approved prior to construction. It is advised that the documents be submitted prior to recording to allow comment by the Municipal Attorney. Modification of these requirements can only be based upon:
1) Intervening local government requirements of a more stringent nature, such as the requirement of a maintenance agreement and posting of bond by the developer.
2) The uniqueness of the project requiring an alternative entity. Such alternative entity must be evaluated upon an individual basis with any and all necessary agreements or easements in effect before approval will be given.