(A) The Common Council of the City of Washington, Indiana has set the following to be the minimum checklist requirements for review of a proposed drainage plan.
(B) Drainage plans must include:
(1) One copy of a certified site plan showing the following items for the subject tract:
(a) Site boundaries including bearings and lengths of property lines, total area of tract, north arrow and scale;
(b) Names and record deed information for owner of the subject tract and for all adjoiners to the subject tract;
(c) Record and/or platted utility easements;
(d) Spot elevations and existing contour lines at 1-foot intervals, and reference bench marks. Existing contour lines at 2-foot intervals may be used for project sites determined to have an excessive degree of relief. The City Engineer shall be consulted with for this determination;
(f) Adjourning highways, county roads, city streets and alleys, including names, right-of-way widths, pavement widths and type of surface;
(g) Locations of all existing on-site and off-site utilities;
(h) Existing drainage pattern including existing building structures, driveways and parking areas;
(i) Locations and dimensions of all existing building structures, driveways and parking areas;
(j) Locations and descriptions of vegetative cover such as grass, brush, weeds and trees; and
(k) Predominate soil types and descriptions as shown in the Natural Resources Conservation Service county soil survey.
(2) Narrative describing existing land use of proposed site and adjoining properties.
(3) One copy of a certified site plan showing the following items for the proposed development of the subject tract:
(a) Finish floor elevations, curb and pavement elevations, contour lines, storm sewer manhole and inlet grate and invert elevations;
(b) Locations and dimensions of proposed building structures, pavement, vegetative areas, utilities, storm sewers, manholes, inlets, ditches, swales, ponds and lakes; and
(c) Location, dimensions and details of proposed storm water detention facility.
(4) Narrative describing the proposed land use of the site and description of the proposed drainage system and detention facility.
(5) Drainage design calculations prepared and certified by and Indiana Registered Professional Engineer or Land Surveyor utilizing the following criteria:
(a) Calculation of the undeveloped 10-year frequency storm peak flow rate from the subject tract;
(b) Calculation of the developed 25-year frequency storm peak flow rate from the subject tract;
(c) Calculations and details for detaining a developed 25-year frequency storm peak flow rate to an undeveloped 10-year frequency storm peak flow rate;
(d) For projects located in flood prone sensitive areas, increased developed storm frequencies may be required. The City Engineer shall be consulted with for this determination; and
(e) All methods and calculations shall be in accordance with acceptable standards as outlined in the HERPICC Stormwater Drainage Manual published by the Purdue Research Foundation, West Lafayette, Indiana.
(6) Individual new residential structures to be constructed on lots situated within existing platted additions and/or subdivisions, or on unplatted tracts shall be exempt from the drainage review requirements.
(7) Individual commercial developments on tracts less than or equal to 0.25 acre shall be exempt from the drainage review requirements.
(8) New residential subdivisions, commercial developments over to 0.25 acre, and all industrial developments shall conform with the drainage review requirements.
(9) Depending on the nature, complexity and location of the project, and the flood prone sensitivity of the project area, more or less information and data may be required by the City Engineer.
(10) The requirements of this chapter must be complied with prior to the issuance of a building permit under Chapter 152 of the Washington Code of Ordinances.
(11) Notwithstanding the above, all developers shall comply with Chapter 52B Stormwater Management. No permits shall be issued until compliance has been verified by the MS4 operator.
(Prior Code, § 155.52) (Am. Ord. 8-99, passed 8-9-1999; Am. Ord. 13-2024, passed 7-22-2024)