A storm water management plan shall be required with all permit applications and will include sufficient information (e.g., maps, hydrologic calculations, etc.) to evaluate the environmental characteristics of the project site, the potential impacts of all proposed development of the site, both present and future, on the water resources, and the effectiveness and acceptability of the measures proposed for managing storm water generated at the project site. The intent of this plan is to determine the type of storm water management measures necessary for the proposed project, and ensure adequate planning for management of storm water runoff from future development. To accomplish this goal the following information shall be included in the plan:
(a) A map (or maps) at no smaller than 1"=20' scale indicating the location of existing and proposed features within (100) feet of the site, and the larger common plan of development, if applicable. Features include, but are not limited to buildings, roads, parking areas, utilities, structural storm water management, two (2) foot maximum interval contour lines, and flow lines, easements, and construction and post-construction BMPs. The map(s) will also clearly show proposed land use with a calculation of acreage and percentage impervious cover under pre- and post-development conditions, drainage patterns, and locations of property lines and easements.
(b) Detailed drawings of structural post-construction storm water management features.
(c) A sediment and erosion control plan showing locations of erosion and sediment controls to be employed during each operation of the soil disturbing sequence at specific locations. Include the location of areas likely to require temporary stabilization during the course of site development, and stone construction entrances for ingress and egress of the site. Also show sediment ponds, including their sediment settling volume and contributing drainage area.
(d) A map showing areas designated for storage or disposal of wastes, including dumpster areas, areas designated for cement truck washout, and vehicle fueling.
(e) Sufficient engineering analysis to show that the proposed storm water management measures are capable of controlling runoff from the site in compliance with this chapter and the specifications of the Storm Water Design Manual or OEPA requirements, whichever is more stringent. Include a tributary drainage area map, hydrologic and hydraulic design calculations for the pre-development and post-development conditions for the design storms specified in the Storm Water Design Manual. Such calculations shall include (i) tributary drainage areas, (ii) description of the design storm frequency, intensity and duration, (iii) time of concentration, (iv) runoff coefficients, (v) peak runoff rates and total runoff volumes for each watershed area, (vi) culvert capacities, (vii) flow velocities, and (viii) data on the increase in rate and volume of runoff for the design storms referenced in the Storm Water Design Manual..
(f) A project description including the type and purpose of soil disturbing activities and a description of the larger common plan of development, if applicable. A written justification of proposed changes in natural conditions may also be required. Note scheduling and phasing of construction activities. Mark the total area of the site that is expected to be disturbed (i.e. clearing, grubbing, excavation, filling or grading, including off-site borrow or stockpile areas).
(g) A written or graphic inventory of the natural resources at the site and surrounding area as it exists prior to the commencement of the project and a description of the watershed and its relation to the project site. This description should include a discussion of soil conditions, any known pollutants, prior land uses, forest cover, topography, wetlands, steep slopes, location and name if immediate receiving stream or surface water, sensitive areas receiving runoff from the development area, and other native vegetative areas on the site. Particular attention should be paid to environmentally sensitive features that provide particular opportunities or constraints for development.
(h) If a storm water management control measure depends on the hydrologic properties of soils (e.g., infiltration facilities), 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 pits shall be determined based on what is needed to determine the suitability and distribution of soil types present at the location of the control measure.
(i) The City of Loveland may also require a storm water management plan to consider the maximum development potential of a site under existing zoning, regardless of whether the applicant presently intends to develop the site to its maximum potential.
(j) The applicant shall assure that all other applicable environmental permits have been acquired for the site prior to approval of the storm water design plan.
(k) The name, address, and telephone number of all persons having a legal interest in the property and the parcel number of the property or properties affected.
For development or redevelopment occurring on a previously developed site, an applicant shall be required to include within the storm water management plan measures for controlling existing storm water runoff discharges from the site in accordance with the standards of this chapter and the Storm Water Design Manual.
(Ord. 2022-31. Passed 4-12-22.)