A. The design of all regulated activities shall include the following steps in sequence to minimize stormwater impacts:
(1) The applicant is required to evaluate practicable alternatives to the surface discharge of stormwater, the creation of impervious surfaces and the degradation of waters of the commonwealth, and must maintain as much as possible the natural hydrologic regime of the site.
(2) An alternative is practicable if it is available and capable of being done after taking into consideration cost, existing technology and logistics in light of overall project purposes, and other municipal requirements.
(3) All practicable alternatives to the discharge of stormwater are presumed to have less adverse impact on quantity and quality of waters of the commonwealth unless otherwise demonstrated.
B. The applicant shall demonstrate that they designed the regulated activities in the following sequence to minimize the increases in stormwater runoff and impacts to water quality:
(1) Prepare an existing resource and site analysis map (ERSAM), showing environmentally sensitive areas including, but not limited to, steep slopes, ponds, lakes, streams, wetlands, hydric soils, vernal pools, floodplains, stream buffer zones, hydrologic soil groups A and B (areas conducive to infiltration), special geologic features, any existing recharge areas and any other requirements outlined in Chapter 515, Subdivision and Land Development.
(3) Prepare a draft project layout avoiding sensitive areas identified in Subsection B(1).
(4) Identify site specific existing conditions drainage areas, discharge points, recharge areas and hydrologic soil groups A and B.
(5) Evaluate nonstructural stormwater management alternatives.
(a) Minimize earth disturbance.
(b) Minimize impervious surfaces.
(c) Break up large impervious surfaces.
(6) Satisfy infiltration objective (§ 505-125) and provide for stormwater pretreatment prior to infiltration. Pretreatment may not be necessary for rooftop runoff which enters the infiltration facility directly from a roof leader.
(8) Determine what management district the site falls into (Appendix D) and conduct an existing conditions runoff analysis.
(9) Prepare final project design to maintain existing conditions drainage areas and discharge points, to minimize earth disturbance and impervious surfaces, and to the maximum extent possible, to ensure the remaining site development has no surface or point discharge.
(10) Conduct a proposed conditions runoff analysis based on the final design and to meet the release rate and in turn the overbank flow and extreme event requirements (§ 505-128).
(11) Manage any remaining runoff through treatment prior to discharge, as part of detention, bioretention, direct discharge or other structural control.