(1) Applicability. The standards of this section shall apply to all development in the city.
(2) Drainage design.
(A) No development will be approved unless there is an outlet for all storm water. Provisions shall be made to accommodate effectively the increased runoff caused by changed soil and surface conditions during and after development. It may be necessary to direct surface water to a drainage ditch, stream or existing storm system which has the capacity to carry the flow. No natural drainage course shall be altered and no fill, buildings or structures shall be placed in, on or over it, unless provision is made for the flow of water in a manner satisfactory to the City Engineer. An easement shall be provided on both sides of an existing surface drainage course for the purpose of maintaining, protecting, widening, deepening, enclosing or otherwise improving such stream for drainage purposes.
(B) If the same is across private property, a right-of-way or easement must be obtained by the subdivider or developer in the name of the city, as reviewed and approved by the Planning Department and the City Engineer. These rights-of-way or easements should be shown on the plat, site plan or construction plans, as applicable. A copy of the recorded easement shall be furnished to the Planning Department.
(C) Storm sewer laterals will be provided as directed by the City Engineer for each (house) lot on a street having a curb and gutter.
(D) The design criteria for the drainage system shall be based on the Ohio Department of Transportation design policy and the criteria established by the City Engineer’s office. This criteria shall apply to development along existing roads, as well as those requiring new roads to be constructed. This criteria shall be available upon request from the City Engineer’s office.
1.) Road drainage system. The road storm drainage system shall serve as the local drainage system. It shall be designed to carry roadway, adjacent land and residential or commercial development storm water drainage, as applicable. To prevent excessive pipe sizes, storm sewers shall drain into natural waterways as soon as possible.
2.) Off-road drainage system. The design of the off-road drainage system shall include the watershed affecting the development and shall be extended to a watercourse or ditch adequate to receive the storm drainage.
(E) Storm water management requirements.
1.) The design and construction of storm water management facilities shall require the review and approval of the City Engineer in accordance with the technical criteria described in the County Storm Water Management Program Guidelines as referred to by the city.
2.) Allowable types of storm water management facilities include, but are not limited to:
a.) Retention ponds;
b.) Detention basins;
c.) Underground storage tanks;
d.) Rooftop storage areas;
e.) Parking lot storage areas;
f.) Infiltration/recharge ditches; and
g.) Swales/screening areas.
3.) All project sites or development areas required to implement storm water management practices and facilities shall, at a minimum, limit the peak rate of discharge from the project site or development area to the downstream receiving watercourse as follows:
a.) Storm water management measures shall be required to maintain the post development peak discharge at a level equal to or less than the predevelopment peak discharge rate for a 24-hour duration, two-year frequency storm event;
b.) Storm water management facilities shall be designed to control the volume, timing and rate of flows; and
c.) Velocity reduction devices must be placed at all outlet points, where necessary, to provide a nonerosive flow velocity to the receiving watercourse. The City Engineer may waive these requirements if the characteristics of the receiving watercourse, project site or development area are such that this type of control would be contrary to accepted engineering practice or detrimental to the environment.
(F) Wetlands. Wetlands will be identified on the improvement drawings. If they are going to be changed in any manner, the developer must contact the U.S. Army Corps of Engineers. The County Soil and Water Conservation District has a copy of the wetland resource maps for the county and the city. The County Soil and Water Conservation District will point out such wetlands in its review of the preliminary plan. If a U.S. Army Corps of Engineers permit is required, the permit number shall be shown on the final plat.
(3) Drainage system design and protection.
(A) Flood hazard. If any portion of the land within a subdivision is subject to flooding (floodplains from the federal floodplain map), sewer overflow, elevations or other hazards, due consideration shall be given to such problems in the design of the subdivision, and the floodplain must be shown on the improvement plans and plat.
(B) Dams or basins (embankments). Copies of detailed drawings of proposed dams or basins and all calculations shall be submitted to the City Engineer for approval. The developer or his or her engineer shall apply for a permit from the Ohio Department of Natural Resources, Division of Water, if applicable, and any other applicable agencies.
(C) Protection of drainage systems.
1.) The subdivider shall adequately protect all ditches (roadways and watercourses) to the satisfaction of the City Engineer as shown by calculations made in accordance with the policy of the Ohio Department of Transportation and the subdivision drainage criteria of the City Engineer.
2.) In all cases, any drainage facilities within a subdivision shall be in a stable condition, free from either erosion or sedimentation, and/or other debris. Any damage resulting from erosion, scour, silting of drainageways or blockage of storm drainage systems on and off the development, caused by the construction, shall be corrected at the developer’s expense.
(D) Drainage outlets. Where the City Engineer finds it necessary to clean, alter or reconstruct a natural drainage course or storm sewer system outside the development boundary to provide a storm water outlet, or to prevent damage to other properties due to an increased or accelerated flow, the outlet shall be provided and constructed at the expense of the developer and in accordance with plans and specifications approved by the City Engineer.
(E) Drainage drawings. The developer’s engineer shall make a complete study of the drainage area contributing to the development and submit copies of all data and calculation sheets to the City Engineer for review and approval.
(4) Drainage easements. Where a subdivision is traversed by a drainageway, a storm sewer or drainage easement conforming substantially to the lines of such drainageway shall be provided. The easement shall be a minimum of 20 feet, or as the City Engineer and the PZC may require.
(Prior Code, § 1229.03) (Ord. 2009-21, passed 10-27-2009)