(A) Purpose. These stormwater drainage regulations are intended to minimize off site water run-off, increase on-site infiltration, encourage natural filtration functions, stimulate natural drainage systems, and minimize off site discharge of pollutants. Stormwater shall be managed by the best and most appropriate technology and environmentally-sound site planning and engineering techniques, which may include combined retention facilities, porous paving and piping, and swales; as well as traditional storm sewers and retention basins.
(B) General Requirements. All new development shall make adequate provision for storm or flood water runoff in accordance with the Noblesville Stormwater Technical Standards or the requirements of the jurisdictional agency. The applicant may also be required by the Plan Commission to carry away by pipe or open ditch any spring or surface water that may exist either previously to, or as a result of, the development. The drainage system shall be separate and independent of any sanitary sewerage system. Inlets shall be provided so that surface water is not carried across or around any intersection, or for a distance of more than 400 feet in any gutter. Surface water drainage patterns shall be shown for each lot and block on the development plat or plan.
(C) Public Storm Sewers.
(1) Where a public storm sewer is accessible, the applicant shall install storm sewer facilities. If the Commission determines that a connection to a public storm sewer will eventually be provided as shown in existing local plans and programs, the developer shall make arrangements for future storm water disposal in the development by a public sewerage system at the time the plat or plan receives secondary approval. Provision for such connection shall be incorporated by inclusion in the Performance Bond required for the development.
(2) Drainage facilities shall be located in the road right-of-way where feasible or in perpetual unobstructed easements of appropriate width. Drain facilities shall be provided under driveways so that the flow of water in ditches is not impeded.
(3) Storm sewers, where required, shall be designed according to the Noblesville Stormwater Technical Standards or other methods required by the engineer of appropriate jurisdiction, endorsed by the Technical Advisory Committee, and approved by the Plan Commission, and a copy of the design computations shall be completed in accordance with the Noblesville Stormwater Technical Standards and be submitted along with plans and specifications.
(4) All storm sewers shall be self-cleaning systems without manhole drops.
(5) All below-ground drainage systems, except for underground retention facilities or pipes less then 12 inches in diameter shall be maintained by the city.
(6) All storm sewer facilities shall be provided to comply with the Noblesville Standards and the Noblesville Stormwater Technical Standards.
(7) Ordinance No. 23-4-05 "City of Noblesville Illicit Discharge and Connection Stormwater Ordinance" and all amendments thereto. (See §§ 52.01 et seq.).
(D) Detention/Retention Ponds. If no public storm sewer outlets are available within a reasonable distance, the disposal of storm waters shall be accomplished through a detention pond.
(1) General Requirement.
(a) Where detention/retention facilities or "ponds" are used for stormwater management, they shall accommodate site runoff generated from two-year, ten-year, and 100-year storms considered individually in accordance with the Noblesville Stormwater Technical Standards, unless the detention/retention basin is classified as a dam, in which case it must also meet any applicable dam safety standards.
(b) Runoff greater than that occurring from a 100 year, 24-hour storm shall be passed over an emergency spillway.
(c) Detention/retention shall be provided to limit stormwater discharge to the rates required by the Noblesville Stormwater Technical Standards or the requirements of the jurisdictional agency.
(d) Detention facilities shall be located as far horizontally from surface water and as far vertically from groundwater as is practicable. Detention facilities shall not interrupt the post-development groundwater table, where practicable.
(e) Detention/retention ponds, where required, shall be designed according to the methods recommended by the Noblesville Standards, Noblesville Stormwater Technical Standards, and the engineer of appropriate jurisdiction, endorsed by the Technical Advisory Committee, and approved by the reviewing authority, and a copy of the design computations shall be submitted along with plans and specifications.
(f) All above-ground drainage systems and below-ground stormwater detention systems shall be maintained by the owner(s) of real estate or the neighborhood association or similar group affiliated with the real estate within the development and/or subdivision.
(g) The setback from the right-of-way at the Top of Bank shall be a minimum of 50 feet. (Refer to the Noblesville Standards.)
(h) The setback from a property line not adjacent to a right-of-way at the Top of Bank shall be a minimum of 15 feet. (Refer to the Noblesville Standards.) This setback shall be referred to as an easement for maintenance purposes and so indicated on the construction plans, recorded plats or other recorded documents.
(2) Combined Facilities. Where possible, a detention pond may be created so as to serve several adjacent parcels concurrently, subject to the following criteria:
(a) The pond shall be designed with appropriate capacity to serve all applicable sites, as determined by the Engineer of the applicable jurisdiction.
(b) Provisions for completion of improvements and maintenance, or any applicable bonds in lieu thereof, shall be coordinated between all applicable sites, in a manner acceptable to the attorney of the applicable jurisdiction.
(c) Shared detention ponds should be designed and landscaped as a site amenity to the extent practicable.
(d) The subdivision of lots abutting the combined detention pond shall be subject to § 159.077(B)(5).
(E) Accommodation of Upstream Drainage Areas. A culvert or other drainage facility shall in each case be large enough to accommodate potential runoff from its entire upstream drainage area, whether inside or outside the development. The design engineer shall determine the necessary size of the facility, based on the provisions of the construction standards, Noblesville Stormwater Technical Standards, and specifications assuming conditions of maximum potential watershed development permitted by this chapter.
(F) Effect on Downstream Drainage Areas. The design engineer of the site shall determine if the immediate downstream receiving pipe/culvert, system, or waterways is sufficient to handle the stormwater runoff and note that in the drainage calculations. The engineer of the applicable jurisdiction shall also study the effect of each development on existing farther downstream drainage facilities outside the area of the development. Local government drainage studies together with such other studies as shall be appropriate, shall serve as a guide to needed improvements. Where it is anticipated that the additional runoff incident to the development will overload an existing downstream drainage facility, the Planning Commission may withhold approval of the development until provision has been made for the expansion of the existing downstream drainage facility. No development shall be approved unless adequate drainage will be provided to an adequate drainage watercourse or facility.
(G) Poor Drainage Areas. Whenever a plat is submitted for an area, or is just upstream of an area, which is subject to ponding or flooding, the Plan Commission may approve such application provided that the applicant's design engineer designs a stormwater system to eliminate the ponding or flooding of the site or the immediate downstream area and that it is acceptable by the engineer of appropriate jurisdiction. The plan or system shall be constructed and accepted by the engineer of jurisdiction prior to the approval of said plat.
(H) Floodplain Access.
(1) The Plan Commission shall, when it deems it necessary for the health, safety, or welfare of the present and future population of the area and necessary to the conservation of water, drainage and sanitary facilities, prohibit the development of any portion of the property which lies within the flood plain. Any approvals within the floodplain shall, at a minimum, meet the requirements of the Indiana Department of Natural Resources.
(2) Development plans, primary plats, secondary plats, preliminary development plans and detailed development plans shall delineate the 100-year floodplain and base flood elevations on said plans as referenced on the most current adopted flood insurance rate maps for Hamilton County, Indiana, a part of the National Flood Insurance Program as provided by the Federal Emergency Management Agency.
(I) Drainage Easements. Where a development is traversed by a watercourse, drainage way, channel, or stream, the developer shall provide a stormwater easement or drainage right-of-way conforming substantially to the lines of such watercourse, and of such width and construction as will be acceptable to the Engineer of appropriate jurisdiction. The easement shall be adequately monumented; and, whenever possible, it is desirable that the drainage be maintained by open channel with landscaped banks.
(Ord. 62-12-95, passed 1-22-96; Am. Ord. 55-12-02, passed 1-14-03; Am. Ord. 82-10-05, passed 11-15-05; Am. Ord. 56-11-07, passed 12-11-07; Am. Ord. 32-10-11, passed 11-15-11; Am. Ord. 32-07-19, passed 7-23-19)