No building, grading, or sediment control permit shall be issued until a satisfactory storm water management final plan (or a waiver thereof) shall have undergone a review and been approved by the City after determining that the plan or waiver is consistent with the requirements of this chapter. After review of the storm water management concept plan, and modifications to that plan as deemed necessary by City, a storm water management final plan must be submitted to the City for approval. The storm water management final plan, in addition to the information included in the storm water management concept plan, shall:
1. Be prepared by a licensed professional engineer or landscape architect or individual credentialed in a manner satisfactory to the City.
2. Indicate whether storm water will be managed on site or off site and, if on site, the general location and type of practices, with clear citations to the Iowa Storm Water Management Manual.
3. Include a signed and dated certification under penalty of perjury by the preparer of the storm water management final plan that it complies with all requirements of this chapter and the SUDAS Design Manual, meets the submittal requirements outlined in the Iowa Storm Water Management Manual, is designed to achieve City storm water requirements, and that City is entitled to rely upon the certification as due diligence on the part of City.
4. The storm water management final plan shall also include:
A. A detailed summary of how and why the storm water management final plan differs, if at all, from the storm water management concept plan previously submitted.
B. Contact information, including but not limited to the name, address, and telephone number of all persons having a legal interest in the property and the tax reference number and parcel number of the property or properties affected.
C. Topographic base map, consisting of a 1” = 200’ topographic base map, of the site which extends a minimum of 300 feet beyond the limits of the proposed development and indicates existing surface water drainage including streams, ponds, culverts, ditches, and wetlands; current land use including all existing structures; locations of utilities, roads, and easements; and significant natural and manmade features not otherwise shown. A minimum of 2’ contours shall be shown on-site and 2’ contours outside of the proposed site.
D. Hydrologic and hydraulic design calculations for the pre-development and post-development conditions for the design storms specified in the Iowa Storm Water Management Manual. Such calculations shall include:
(1) Description of the design storm frequency, intensity, and duration;
(2) Time of concentration;
(3) Soil curve numbers or runoff coefficients;
(4) Peak runoff rates and total runoff volumes for each watershed area;
(5) Infiltration rates, where applicable;
(6) Culvert capacities;
(7) Flow velocities;
(8) Data on the increase in rate and volume of runoff for the design storms referenced as referenced in the NOAA Atlas 14, Volumes 8 and 9 (April 2013); and
(9) Documentation of sources for all computation methods and field test results.
E. If a storm water BMP depends on the hydrologic properties of soils (e.g., infiltration basins), then a soils report shall be submitted. The soils report shall be based on on-site boring logs or soil pit profiles. The number and location of required soil borings or soil sites shall be determined based on what is needed to determine the suitability and distribution of soil types present at the location of the BMP.
F. A maintenance and repair plan for all storm water BMPs including detailed maintenance and repair procedures to ensure their continued efficient function. These plans will identify the parts or components of a storm water BMP that need to be maintained and the equipment and skills or training necessary. Provisions for the periodic review and evaluation of the effectiveness of the maintenance program and the need for revisions or additional maintenance procedures shall be included in the plan.
G. A detailed landscaping plan for management of vegetation at the site after construction is finished, including who will be responsible for the maintenance of vegetation at the site and what practices will be employed to ensure that adequate vegetative cover is preserved. This plan must be prepared by a registered landscape architect, landscape designer, or by the soil and water conservation district.
H. Proof of permanent recorded maintenance easements that will ensure access to all storm water BMPs at the site for the purpose of inspection and repair. These easements will be recorded with the storm water management final plan and will remain in effect even with transfer of title to the property.
I. Proof of a recorded maintenance agreement binding on all subsequent owners of land served by storm water BMPs to ensure maintenance and repair in accordance with the specifications of this chapter.
J. Copies of all existing SWPPPS (as required by the City’s COSESCO ordinance) current as of the date of submission of the storm water management final plan for all construction activities related to implementing any on-site storm water BMPs.
K. Proof that the applicant has acquired all other applicable environmental permits for the site, or that no other such permits are required, prior to submission of the storm water management final plan to the City.
L. For lot development impacted by storm water BMPs and conveyance features:
(1) The permit holder shall provide to the Municipal Engineer, or designated City representative, an Elevation Certificate that is signed and sealed by a land surveyor, engineer, or architect authorized by law to certify elevation information.
(2) The Elevation Certificate shall certify that the protected level (lowest opening or protective flood barrier that achieves the same result) of all buildings shall be a minimum of 3 feet above the 100-year water surface elevation of storm water BMPs.
(3) Building foundations adjacent to storm water BMPs and/or storm water infrastructure (i.e. conveyance features, inlets, manholes) shall be 3 feet above the 100-year water surface elevation.
M. Accommodating Upstream Drainage Areas. Any necessary and appropriate storm water BMPs shall be designed to accommodate runoff from any upstream area potentially draining into or through the area to be subdivided, whether such area is inside or outside the area to be subdivided. Such design shall assume that the upstream area upon development or redevelopment will be regulated such that volume of surface water runoff shall be equal to the runoff from the current land use condition.
N. Protecting Downstream Drainage Areas. Any development shall provide for mitigation of any overload condition reasonably anticipated on any existing downstream storm water BMPs outside the area to be subdivided, provided that the development or use of the area to be subdivided creates or contributes to such condition.