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HomeMy WebLinkAboutComments PWE 9/14/2010 ...-t. - ~ "-.. . . Memorandum City of Springfield Date: September 14,2010 Liz Miller, Urban Planner Clayton McEachern, Civil Engineer DRC2010-00020, Blackwell Auto Dealer MDS To: From: Subject: I have reviewed the materials provided with the subject application. The recommended findings and conditions outlined below are provided for your use in preparing the land-use decision. STORMW ATER MANAGEMENT AND OUALITY Finding: Section 4.3-11 O.B of the SDC requires that the Approval Authority shall grant development approval only where adequate public and/or private stormwater management systems provisions have been made as determined by the Public Works Director, consistent with the Engineering Design Standards and Procedures Manual (EDSPM). Finding: Section 4.3-11O.D of the SDC requires that runcoff from a development shall be directed to an approved stormwater management system with sufficient capacity to accept the discharge. Finding: As required in Section 4.3-110.E of the SDC, "a development shall be required to employ drainage management practices approved by the Public Works Director and consistent with Metro Plan policies and the Engineering Design Standards and Procedures Manual." Finding: Section 3.02 of the City's EDSPM states the Public Works Department will accept, as interim design standards for stormwater quality, water quality facilities designed pursuant to the policies and procedures of either the City of Portland (BES), or the Clean Water Services (CWS). Finding: Section 3.03.3.B of the City's EDSPM states all public and private development and redevelopment projects shall employ a system of one or more post-developed BMPs that in combination are designed to achieve at least a 70 percent reduction in the total suspended solids in the runoffgenerated by that development. Section 3.03.4.E of the manual requires a minimum of 50 percent of the non-building rooftop impervious area on a site shall be treated for stormwater quality improvement using vegetative methods. Finding: The vegetation proposed for use in the swales will serve as the primary pollutant removal mechanism for the stormwater runoff, and will remove suspended 'solids and pollutants through the processes of sedimentation and filtration. Satisfactory pollutant removal will occur only when the vegetation has been fully established. 1/ I Date Received: It) 10 Planner: LM ....J. ..~- . . Finding: The plans submitted indicate a drainage bio-swale area; however plans have not been submitted with engineer's analysis, and do not meet suitable criteria for an infiltnition basin. Condition: Prior to approval of the Final Site Plan, the applicant shall submit an analysis of the infiltration swales using the Simplified approach from the Portland Stormwater Management Manual prepared and stamped by a licensed engineer. No drainage study. beyond this is necessary for this development. Condition: The infiltration basins shall be designed in accordance with the details provided in the Portland stormwater manual for either an Infiltration planter or Vegetated Infiltration Swale. No subdrain is necessary as there is not a suitable public stormwater facility to receive any overflow. Plantings shall consist of native grass and shrubs that are suitable to these environments. A native seed mix will be deemed suitable if applied correctly and plants are established to full growth. Condition: To promote plant health and for the infiltration basins to work properly the soil 'must be suitable for infiltration and protected from compaction during construction. To meet this condition the subgrade for the infiltration basins must be decompacted to a minimum depth of 10" by a suitable method (roto-tilling or scarifying will be deemed suitable) FEES AND PERMITS SYSTEMS DEVELOPMENT CHARGE: Pay applicable Systems Development Charges when building permits are issued for developments within the City limits or within the Springfield Urban Growth Boundary. (The cost relates to the amount of increase in impervious surface area, transportation trip rates, and plumbing fixture units. Some exceptions apply to Springfield. Urban Growth areas.) [Springfield Code Chapter II, Article 11] Systems Development Charges (SDC's) will apply to the construction of buildings and site improvements within the subject site. The Charges will be based upon the rates in effect at the time of permit submittal for buildings or site improvements on each portion or phase of the development. OTHER CITY PERMITS: Land & Drainage Alteration Permits (LDAP). [Contactthe Springfield Public Works Department@ 726-5849 for appropriate applications/requirements] I .Jte Received:~ Planner: LM