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HomeMy WebLinkAboutSDP201300009 Review Comments Waiver, variation or substitution requirement 2013-02-08*-&A County of Albemarle Department of Community Development Memorandum To: Ellie Ray, Planning Review From: Michelle Roberge, Engineering Review Date: 8 Feb 2013 Subject: Seminole Trail Fire Station; Critical Slope Waiver Request (SDP- 2013 - 00009) The critical slope waiver request has been reviewed. The engineering analysis of the request follows: Description of critical slope area and proposed disturbance: The critical slopes proposed as being disturbed are man -made slopes of 2:1 that were created when the fire station was constructed. There are three critical slope areas on site; the first critical slope is along Berkmar Drive, the second is located in between the fire station and parking lot, and the third is behind the fire station. The applicant requests to disturb these critical slopes for a proposed building addition, for an access to separate the emergency and non - emergency traffic, and for a proposed mechanical pad. Areas Acres Total site 1.785 acres approximately Critical slopes 0.18 acres 10% of site Critical slopes disturbed .08 acres 44% of critical slopes The critical slope along Berkmar Drive is exempt from the critical slopes waiver due to no reasonable alternative locations for an additional entrance. The critical slope in between the fire station and the parking lot are also exempt provided that retaining walls are designed for areas with an elevation difference of 6' or greater. The critical slope behind the Fire Station will have minimal disturbance for a mechanical pad. I recommend the disturbance of these manmade critical slopes. Compliance with Zoning Ordinance 18 -4.2: "movement of soil and rock" The site will require proper slope construction, control of drainage, and vegetative stabilization to prevent any movement of soil. The elevation of the existing building is much lower than the existing parking lot. The proposed building addition will cut into the existing topography and retaining walls will be required in between the parking lot and the building addition. "excessive stormwater runoff' The critical slope runoff located along Berkmar Drive is currently draining into a culvert under the existing entrance road and routed to a vegetative area south of the fire station. The disturbance of this critical slope and the additional impervious entrance road will increase the runoff. The proposed building addition will also increase the runoff. A stormwater management analysis will determine if the size of the existing culvert needs to be increased and if erosion control measures are warranted in the vegetative area. "siltation" Inspection and bonding by the County will ensure siltation control during construction. Proper stabilization and maintenance will ensure long term stability. Albemarle County Community Development Engineering Review comments Page 2 of 2 "loss of aesthetic resource" The critical slopes on site are manmade and were approved on a site plan for the existing fire station. "septic effluent" The proposed site will not release any septic effluent to the surrounding environment. The site is serviced by public sewer. file: El_csw_PBC_Miller School Critical Slope Waiver SDP201200032.doc