Conference/Public Meeting Agendas/Documents — Packet

DRAFT PROPOSED REVISIONS – OCTOBER 2011 (3) Temperature shall be addressed to ensure no impact on receiving waterway; (4) The encroachment shall only be allowed where the applicant demonstrates that the functional value and overall condition of the special water resource protection area will be maintained to the maximum extent practicable; (5) A conceptual project design meeting shall be held with the appropriate Department staff and Soil Conservation District staff to identify necessary stabilization measures; and (6) All encroachments proposed under this subsection shall be subject to review and approval by the Department. (d) A stream corridor protection plan may be developed by a regional stormwater management planning committee as an element of a regional stormwater management plan, or by a municipality through an adopted municipal stormwater management plan. If a stream corridor protection plan for a waterway subject to subsection 25- 29.4g,8. has been approved by the Department of Environmental Protection, then the provisions of the plan shall be the applicable special water resource protection area requirements for that waterway. A stream corridor protection plan for a waterway subject to paragraph g,8. shall maintain or enhance the current functional value and overall condition of the special water resource protection area as defined in paragraph g,8(a)(1) above. In no case shall a stream corridor protection plan allow the reduction of the Special Water Resource Protection Area to less than one hundred fifty (150) feet as measured perpendicular to the waterway subject to this subsection. (e) This subsection does not apply to the construction of one (1) individual single family dwelling that is not part of a larger development on a lot receiving preliminary or final subdivision approval on or before the effective date of the

family dwelling that is not part of a larger development on a lot receiving preliminary or final subdivision approval on or before the effective date of the Stormwater Management Rules*, provided that the construction begins on or before five (5) years from effective date of the Stormwater Management Rules.* (Ord. No. 2063-06 § 4) 25-29.5 Calculation of Stormwater Runoff and Groundwater Recharge. a. Stormwater runoff shall be calculated in accordance with the following: 1. The design engineer shall calculate runoff using one of the following methods: (a) The USDA Natural Resources Conservation Service (NRCS) methodology, including the NRCS Runoff Equation and Dimensionless Unit Hydrograph, as described in the NRCS National Engineering Handbook Section 4-Hydrology and Technical Release 55 - Urban Hydrology for Small Watersheds; or (b) The Rational Method for peak flow and the Modified Rational Method for hydrograph computations. 2. For the purpose of calculating runoff coefficients and groundwater recharge, there is a presumption that the preconstruction condition of a site or portion thereof is a wooded land use with good hydrologic condition. The term "runoff coefficient" applies to both the NRCS methodology at subsection 25-29.5a,1(a) and the Rational and Modified Rational Methods at subsection 25-29.5a,1(b). A runoff coefficient or a groundwater recharge land cover for an existing condition may be used on all or a portion of the site if the design engineer verifies that the hydrologic condition has existed on the site or portion of the site for at least five (5) years without interruption prior to the time of application. If more * Editor's Note: Ordinance No. 2063-06 codified herein was adopted March 21, 2006. 168