(a) Design Requirements. These regulations shall apply to any earth-disturbing activity where more than 20,000 square feet of soil is disturbed, including residential, commercial or industrial development as well as non-structural activities such as pond construction, logging operations, site clearing and grubbing, etc.
(1) These regulations shall not apply to the construction of a single-family residential structure disturbing less than 20,000 square feet, on a lot which is not included in a Stormwater Management or Sediment Control Plan for a larger development. However, the owner of record for the property on which the construction will take place shall provide a letter of agreement wherein the owner states that appropriate sediment control measures will be utilized to minimize soil erosion and off-site sedimentation.
(2) For all other residential, commercial, industrial or non-structural earth-disturbing activities where more than 20,000 square feet of soil will be disturbed during construction, the owner of the property shall develop a Stormwater Management and Sediment Control Plan, prepared in accordance with subsection (l) hereof. The plan shall contain sufficient detailed information, drawings and explanations to accurately describe the methods to be employed to manage stormwater run-off, soil erosion and off-site sedimentation, during and after construction. No earth- disturbing activities shall begin prior to the approval of this plan by the Stormwater Manager.
(3) The Stormwater Manager shall be notified at least 48 hours in advance of any earth-disturbing activity for which a Stormwater Management and Sediment Control Plan is required. The Stormwater Manager shall also be advised when all earth-disturbing activities have been completed.
(b) Protection of Adjacent Properties. Properties adjacent to the construction site shall be protected from erosion or flooding as a result of earth-disturbing activity or construction on a site. This may be accomplished by a Stormwater Management/Sediment Control Plan (SWM/SCP) that may incorporate a well-vegetated buffer strip at the lower parameter of the property, and run- off control structures such as detention/retention ponds, sediment basins, filter strips, sediment control fences, or a combination of such devices.
(c) Installation of Sediment Control. Sediment basins and traps, diversion dikes, sediment fences or other similar measures intended to trap sediment on-site shall be constructed as a first step in the excavation/grading process, and shall be made functional before any up-slope land disturbance occurs. Earthen structures such as dams, dikes, and diversion structures shall be seeded or mulched within seven (7) days, weather permitting. Slopes that are later found to be eroding excessively shall receive additional stabilization treatments during construction until the erosion/sedimentation problem is corrected.
(d) Sediment Basins. Where five (5) or more acres of land will be subject to earth- disturbing activity within a single watershed, stormwater from that watershed shall pass through a sediment basin or other suitable sediment trapping structure with storage capacity adequate for the calculated run-off from that drainage area. The Stormwater Manager may require that sediment basins be constructed in smaller drainage areas where deemed necessary, due to soil conditions, topography, or other conditions on a site. Unless otherwise designated, sediment basins are considered to be temporary, and shall be removed following final stabilization of the site.
(e) Storm Sewer Inlet Protection. All storm sewer inlets, catch basins, sanitary sewer manholes, field tile drops, and similar man-made conduits that are made operable during construction shall be protected so that sediment-laden water will not enter the conveyance system without first being filtered or otherwise treated to eliminate sediment.
(f) Cut and Fill Slope Protection. Cut and fill slopes shall be designed and constructed in a manner that will minimize erosion. Consideration shall be given to the length and degree of slope, soil type, up-slope drainage areas and other applicable conditions. Slopes that are found to be eroding excessively during construction shall be provided with additional slope stabilizing measures as recommended by the Stormwater Manager until the problem is corrected. The following guidelines are provided as a guide:
(1) Roughened soil surfaces are generally preferable to smooth surfaces on slopes.
(2) Diversions shall be constructed at the top of long and/or steep slopes. Terraces may also be used to reduce the length of slopes.
(3) Concentrated stormwater should not be allowed to flow down a cut or fill slope unless contained within an adequate re-enforced channel, flume or slope drain structure.
(4) Whenever a slope face crosses a water seepage plane that endangers the stability of the slope, adequate drainage or other protection shall be provided.
(g) Working in or Crossing Watercourses. Construction equipment and vehicles should be kept out of watercourses whenever possible. Where a live (wet) watercourse must be crossed regularly by construction vehicles, a temporary culvert or other approved vehicular stream-crossing structure may be required. Where in- channel work is necessary, precautions shall be taken to stabilize the work area during and after construction to minimize erosion. Permits for channel work may be required by the U.S. Army Corps of Engineers to perform in-stream channel projects.
(h) Stormwater Run-off Calculations. To prevent damages from downstream properties from accelerated stormwater run-off, a stormwater management plan shall describe methods that will be used to reduce both the volume and rate of run-off to pre-development rates.
(1) The peak discharge rate from the critical storm and all more frequent storms occurring under post-development conditions shall not exceed the peak discharge rate of run-off from a one (1) year frequency, 24 hour storm occurring on the same drainage area under pre- development conditions.
(2) Storms of less frequent occurrence (longer return periods) than the critical storm up to the 100 year storm have peak run-off discharge rates no greater than the peak run-off rates from equivalent storms under pre- development conditions. Consideration of the 1, 2, 5, 10, 25, 50 and 100 year storms will be considered adequate in designing to meet this requirement.
(3) The critical storms for a specific drainage area shall be determined as follows:
A. Run-off shall be calculated using the Natural Resource Conservation Service (NRCS) TR-55 Urban Hydrology for Small Watersheds, to determine the total volume (acre-feet) of run-off from a one (1) year, 24 hour storm occurring on the development site drainage area before and after development.
B. From the volumes determined in subsection (h)(3)A. above, determine the percent increase in volume of run-off due to development, and then select the critical storm from the following table:
If the percentage of increase in volume of run-off is: | ||
Equal to or greater than: | Less than: | The critical storm will be |
-- | 10 | 1 year |
10 | 20 | 2 year |
20 | 50 | 5 year |
50 | 100 | 10 year |
100 | 250 | 25 year |
250 | 500 | 50 year |
500 | -- | 100 year |
For example, if the percent increase between the pre-development and post-development run-off volume for one (1) year storm is 35%, the critical storm is a five (5) year storm. The peak discharge rate of runoff for all storms up to this frequency shall be controlled so as not to exceed the peak discharge rate from the one (1) year frequency storm under pre- development conditions in the development drainage area. The post- development run-off from all less frequent storms need only be controlled to meet the pre-development peak discharge rate for each of those same storms.
(4) Methods for controlling increases in the rate and volume of stormwater run-off may include, but are not limited to, the following:
A. Retarding flow velocities by increasing friction. For example, using grass-lined road ditches, rather than paved street gutters where practical, and discharging roof water to vegetated areas, or grass and rock-lined drainage channels.
B. Grading and construction of terraces or diversions to slow run-off by diffusion, or use of grade control structures, such as check dams, to provide a level of control in flow paths and/or existing drainage ways.
C. Induced infiltration of increased stormwater run-off into the soil where practical. For example, constructing special infiltration areas where soils are suitable, retaining topsoil for all areas to be re-vegetated, or providing good infiltration areas with proper emergency overflow facilities.
D. Provisions for detention and retention of stormwater, with properly designed retention basins being preferred. For example, utilizing permanent ponds and lakes as stormwater retention basins that provide multiple use areas for stormwater detention, recreation, wildlife, fire protection and aesthetics. Constructed wetlands, dry detention basins or subsurface storage areas are other options.
(i) Permit Processing. All applications for Stormwater Management Permits shall be filed with the Stormwater Manager prior to the start of any earth-disturbing activity. The Stormwater Manager shall have 30 days to review such applications, and shall approve, approve with corrections and modifications, or disapprove the permit. If the permit is not approved, the Stormwater Manager shall submit comments, drawings or other material to explain why the permit could not be approved. Permits that are granted may fall into one (1) of the following categories:
(1) Approved Without Further Action. (Letter of No Interest/Regulations not Applicable.)
(2) Approved - Sediment Control Agreement Required. Owner of record shall submit a letter of agreement regarding intent and methodology to control silt and sedimentation from on- site erosion.
(3) Approved - Sediment Control Plan is Required.
(4) Permit Denied.
(j) Letter of Agreement. For small projects disturbing less than 20,000 square feet, or projects where stormwater run-off and soil erosion can be reasonably contained within the project site, a simple letter of agreement may be provided by the developer indicating his intention and the methods that will be employed to control stormwater run-off and sediment migration during construction. The terms and conditions of this agreement shall be at the discretion of the Stormwater Manager.
(k) Residential Dwellings on Individual Lots.
(1) For residential lots in subdivisions for which there is an approved Stormwater Management/Sediment Control Plan no SWM/SCP permit shall be required unless the builder/developer proposes to modify the previously approved plan.
(2) On lots less than 20,000 square feet, the property owner and/or contractor shall follow these minimal standards for construction of single-family homes on lots within subdivisions for which a previously approved SWM/SCP exists.
A. Drainage patterns and drainage areas as shown on the original SWM/SCP will be preserved, and shall not be modified except with specific approval from the Stormwater Manager.
B. Clearing and site excavation shall be done so that only active construction sites are disturbed. Pre- existing vegetation shall be preserved on other areas of the subdivision for as long as possible.
C. Temporary seeding (annual rye, oats, etc.) and/or mulch shall be applied to bare areas that will not be worked within the next 30 days.
D. Stockpiles of soil shall be stabilized or protected with sediment trapping measures such as straw bales, silt fences, etc.
E. Silt fences shall be installed on all down-slope sides of the project to control sheet flow run-off. Silt fences shall not be constructed within pre-existing natural drainage courses or areas of concentrated flow.
F. Sediment traps and check dams shall be installed where necessary to control run-off.
G. Inlet protection devices shall be installed to protect all functional storm sewers, catch basins, manholes, etc.
H. A construction access drive, consisting of coarse crushed rock or large gravel shall be installed at the beginning of the excavation process to reduce mud from the site from tracking into the street. (Size #4-6 stone or larger is recommended.)
I. Mud and sediment that accumulates in the street or along gutters or in ditches shall be removed daily. Sediment/mud shall be removed by scraping or shoveling. Flushing of sediment into catch basins or drains is not permitted.
J. Downspouts should be drained across the surface of the property whenever possible.
(l) Stormwater Management/Sediment Control Plans. For all other types of development for which a Stormwater Management/Sediment Control Plan is required, the property owner or developer shall submit the following information for review:
(1) Project Description: Briefly describe in written and map form the extent and nature of land-disturbing activity. Make specific reference to any item that may not be readily evident on any improvement plans.
(2) Description of Existing Site: Describe the physical conditions of the site, or present maps or plans that depict existing topography, existing drainage patterns, soil types, steepness of slopes, and nearest distance from any earth-disturbing activity to any natural stream or active watercourse.
(3) Describe the Best Management Practices (BMP) that will be utilized to protect areas having greater potential for serious erosion or sedimentation, such as stream crossings, steep slope areas, downstream ponds, or roadways, and any other areas that may be negatively effected by soil erosion or stormwater run-off from the construction site.
(4) Include estimations and calculations for both pre- development and post-development peak discharges, using the TR-55 method. Include determination of the critical storm and demonstrate how run-off from upper watersheds have been considered in the calculations. Describe how increased stormwater run-off will be managed on the site. (There is no requirement to detain run-off from upstream properties.)
(5) Indicate on a map of the project or on the construction plan sheet any areas defined as wetlands by the U.S. Army Corps of Engineers. If a permit is required from the U.S. Army Corps of Engineers for any work involving the project, please submit a copy of the application for such permit.
(6) If applicable, submit a copy of the Ohio EPA "NOI" or NPDES permit issued for the project. Contact the Ohio EPA for additional information and permit requirements.
(7) Submit a detailed set of plans for the proposed project that shall include at least the following:
A. A map drawn to scale indicating the construction site and the surrounding area, indicating all abutting streets, drainage courses, adjacent property owners, etc.
B. Detailed construction plans, drawn at a max scale of 1" = 200', and 1" = 50' for those areas of concentrated earth-disturbing activity. The construction plans shall show existing topography at l' contour intervals, and the exact locations of ponds, lakes, watercourses, etc., within 200 feet of the excavation activity.
C. A detailed grading plan showing the limits of clearing and grubbing activity, excavation or grading, and final site contours, and all proposed drainage patterns, watershed boundaries and acreage.
D. Plans for all BMP to be installed on the site for the control of stormwater run-off or soil erosion and sedimentation. The location and design to be used for each BMP, along with any contractor's notes for installation shall be shown on the plan. All stormwater detention or retention structures shall be drawn to scale, and shall include calculations for the watershed that such facility is to serve along with the holding capacity of this installation.
E. An approximate construction schedule/sequence for the contractor, indicating an approximate start date and time frame for each major construction phase of the project, including but not limited to:
1. Initial clearing and grubbing: Attempt to plan this work to leave as much natural vegetation undisturbed as possible.
2. The schedule for installation of BIVIP structures, temporary and/or permanent. These should be installed within seven (7) days of clearing and grubbing.
3. Rough site grading, roadway grading, etc.
4. Installation of underground utilities, drainage systems, etc.
5. Final roadway grading, paving, and final site grading.
6. Application of temporary seeding, mulch or other soil stabilization materials to any areas that will not be "worked" within 30 days.
7. Excavations for construction of buildings or other structures and final site grading.
8. Final site seeding, mulching, etc.
9. Removal of temporary erosion control measures.
F. The landowner/contractor shall submit details describing the temporary and final soil stabilization measures to be used on the project, such as seeding types and application rates, fertilization rates, types of stabilization fabrics that may be used, along with estimated quantities.
G. The landowner/contractor shall furnish a schedule, and the name and phone number of the person responsible for maintenance of all erosion and sediment control measures until the project is completed.
H. All plans and specifications and drainage calculations shall be certified by a registered professional engineer, licensed in the State of Ohio.
I. A plan review and filing fee as specified by the City of Crestline.
(m) Stormwater Manager Plan Review.
(1) The Stormwater Management and Sediment Control (SWM/SCP) shall be submitted to the Stormwater Manager. No construction shall commence until the final plan has been approved by the Stormwater Manager.
(2) Within 30 days of receipt of a SWM/SCP, the Stormwater Manager shall convey to the owner, or his appointed representative, the plan's status, as to its compliance or non-compliance. A ruling of noncompliance shall include specific plan deficiencies, as well as the procedures for filing a revised plan.
(3) At the time a revised plan is submitted, a new 30-day period begins. All approved plans shall remain valid for one (1) year from date of approval.
(n) Inspection and Compliance. If, in the opinion of the Stormwater Manager, immediate and irreparable damage will occur, because of a violation, he/she may take appropriate action to seek a correction of the problem without delay. Enforcement action shall proceed as follows:
(1) Issuance of a letter detailing the nature of the violation, with a notice to correct within 48 hours.
(2) If no response is indicated, a stop work order shall be issued.
(3) If a violation does exist, and no corrective action is taken by the landowner/ contractor, the Law Director may seek an injunction, or some other appropriate relief, in order to abate excessive erosion, or sedimentation, and thereby secure compliance with these regulations. In granting relief, the court may order construction of sediment control improvements, or the implementation of other control measures.
(4) A final inspection will then be made, to determine if the criteria of these regulations has been satisfied, with a final report sent to the Stormwater Manager, relevant to the status of compliance, or non-compliance.
(o) Variance. A duly appointed Appeals Board may grant a variance to these regulations, whenever an owner, or his appointed representative, can show evidence that a hardship exists, whereby compliance with these regulations is not appropriate, based upon the following:
(1) That exceptional and/or unusual topographic or other physical conditions exist that are peculiar to this particular parcel of land.
(2) That the peculiar conditions, noted in paragraph (o)(1) above, did not result from any previous actions by the owner.
(3) That such a literal interpretation of these regulations would deprive the owner of rights that are enjoyed by other property owners.
PLEASE NOTE: Adverse economic conditions shall not be considered a valid reason, or hardship, for a variance request to be granted. No variances will be granted, where activities occur, that would defeat the purpose of these regulations. Requests for a variance should be submitted to the Stormwater Manager, stating the specific variances being sought, and including sufficient data to justify the granting of such variances.
(Ord. 2787. Passed 11-26-07.)