§ 561-224 — Professionally prepared and certified drainage plans

Sec. 561-224. - Professionally prepared and certified drainage plans.

(a) A drainage plan fulfilling the requirements of this section shall be submitted to the division of construction and business services for approval before a drainage permit can be obtained to accomplish a land alteration, unless the land alteration is such that a drainage permit can be obtained in accordance with section 561-225. The drainage plan must be submitted in a manner determined by the administrator as assigned by the deputy director of the division and shall indicate in a precise way the work to be accomplished pursuant to the drainage permit. A copy of the drainage plan will remain on file in the division. The following information must be submitted for approval: (1) Construction features. The drainage plan shall demonstrate and describe surface and subsurface drainage and include the following: a. Scale; arrow; contours and USGS benchmarks: The drainage plan shall be drawn to scale, preferably one (1) inch per fifty (50) feet, and an arrow indicating north shall appear on each page. Existing land contours shall be shown, with one-foot contours for land with a slope flatter than ten (10) percent, two-foot contours for slopes equal to or greater than ten (10) percent but flatter than twenty (20) percent, and five-foot contours for slopes equal to or greater than twenty (20) percent. A benchmark, which is easily accessible and relocatable, shall be shown. The benchmark may be assumed at the discretion of the administrator as assigned by the deputy director of the division if the area contains less than three (3) acres, but otherwise shall be determined by USGS datum. b. Location and vicinity map: A map that indicates the location and vicinity of the proposed land alteration shall be included in the drainage plan. c. Existing and proposed drainage facilities: The drainage plan shall show the locations of all existing and proposed drainage facilities. Storm drains, manholes and other structures shall be located in the plans by dimensions from traverse lines, property markers or road centerlines. Coordinates of manholes and bearings of storm drains shall be included and based either on the state's coordinate system or other acceptable horizontal and vertical datum. If applicable, the drainage plan should show the direction of flow, elevation of inverts, gradient and size of existing and proposed storm drains. The design calculations shall include the capacity of existing and proposed storm sewers. d. Plan and profile: The plan shall be shown at the upper portion of the drawing. The plan, generally, shall be drawn on a scale of one (1) inch equals fifty (50) feet. The plan shall show appropriate right-of-way and easement limits. The profile shall be shown under the plan and shall extend a sufficient distance downstream of the outlet to allow any pertinent information concerning the outfall channel to be shown. The storm drain and inlet profile shall generally be drawn on a scale of one (1) inch equals fifty (50) feet horizontal, one (1) inch equals five (5) feet vertical. Where a storm drain is located in an existing or proposed pavement or shoulder, the centerline grade of the road shall be shown. Where a storm drain is located outside pavement or shoulder, the existing ground over the storm drain with proposed grading shall be shown. If the storm drain is to be constructed on fill, the profile of the undisturbed earth, at drain location, shall be shown. (2) Design calculations. Design calculations are required as part of the drainage plan and shall specifically include: a. Estimation of stormwater runoff: 1. Drainage area map (scale one (1) inch equals 200 feet) indicating contours at two-foot intervals and limits of one-hundred-year floodplain, where applicable, as well as the watershed and sub-watershed boundaries with their respective areas labeled; 2. Weighted runoff coefficient computations; and 3. Time of concentration computation indicating overland flow time and flow time in the swale, gutter, pipe and/or channel. b. Close conduit and open channel design computations: 1. Size of pipe or channel cross section; 2. Pipe or channel inverts and slope in percent; 3. Roughness coefficient; 4. Flowing velocities in feet per second; and 5. Design capacity in cubic feet per second. c. Head loss computations in manholes and junction chambers. d. Inlet casting capacity computations. e. Hydraulic gradient computations, wherever applicable. f. Post-construction water quality calculations such as, but not limited to, design parameters. Such design calculations shall conform to the standards of Article III, Division 5 of this chapter and all regulations promulgated thereunder. (3) Construction water quality information. Adequate and appropriate construction stormwater quality controls including, but not limited to, erosion and sediment controls, dewatering filter, pollution prevention, concrete and cementitious washout containment, inlet protection, and other information as required by the National Pollutant Discharge Elimination System (NPDES Construction Stormwater General Permit administered by the State of Indiana, and regulations adopted by the board of public works pursuant to this chapter. (4) Existing features. Verification that existing water quality and quantity drainage facilities to remain anywhere on the parcel have been inspected and maintained to function as originally designed and permitted. (5) Contaminated soils. Inclusion of information regarding the presence, or lack thereof, of contaminated soils to be disturbed during construction and the impact from or to stormwater shall be included. Said information shall include the following: a. The applicant shall consider implications of stormwater on existing contaminated soils and address this concern in the design and Technical Information Report. b. The design shall provide measures to mitigate movement of contaminants off site and shall include the typical fate and transport of the contaminants present. (6) Additional information. The administrator as assigned by the deputy director of the division shall be empowered to require such additional information to be included in a drainage plan that is necessary to evaluate and determine the adequacy of the proposed drainage facility. (7) Certification required. All drainage plans submitted under this section must be certified by a registered professional engineer, land surveyor or architect engaged in storm drainage design under whose supervision the plans were prepared. The certificate shall be in a form prescribed by the division. (b) The approval of a drainage plan by the division under this section shall be valid for a period of one (1) year from the date such approval was granted, or until the drainage permit for which the plan was submitted is issued, whichever occurs first. However, prior to the issuance of the permit, if there are any material changes to an approved drainage plan or circumstances that cause the drainage plan to be inaccurate or incomplete, then a new or corrected drainage plan shall be submitted to and approved by the division as a precondition for obtaining a drainage permit. All conditions of the approval of a drainage plan shall be met prior to issuance of a permit. The administrator as assigned by the deputy director of the division of construction and business services may, for good cause shown in writing, extend the validity of the drainage plan approval for an additional period that is reasonable under the circumstances.

(Code 1975, § 10½-33; G.O. 168, 1999, § 14; G.O. 15, 2001, § 54; G.O. 3, 2002, § 10; G.O. 63, 2009, § 40; G.O. 41, 2016, § 2; G.O. 16, 2022, § 14; G.O. 33, 2023, § 4)