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HomeMy WebLinkAboutZMA201300017 Review Comments Zoning Map Amendment 2014-04-15*-&A County of Albemarle Department of Community Development Memorandum To: Claudette Grant, Senior Planner From: Michael Koslow, Senior Civil Engineer Rev. 1: Glenn Brooks, County Engineer Date: 17 December 2013 Rev. 1: 10 Feb 2014 Rev.2: 15 Apr 2014 Subject: Spring Hill Village (ZMA201300017) The proposed rezoning of parcel 90 -28 has been reviewed. The following comments are provided for your review: 1. Please provide more information regarding the proposed underground manufacturered 30,000 cft Stormtrap Best Management Practice (BMP) proposed. Will need to know if conceptually this could provide the treatment for Virginia Stormwater Management Permit (VSMP) requirements for at least 12.99 Ac of contributing watershed area. Rev. 1: Underground facilities are not recommended in this setting. Adequate runoff capture will be too difficult, and treatment solely by manufactured underground facilities does not appear adequate under anticipated new water quality regulations. Rev.2: Stormwater facilities are better situated toward the lower side of the site with this revision. Adequate capture of runoff on at -grade inlets along a steep road may still prove unreliable. 2. It appears that the application proposes internal private roads with slopes up to 12%. County ordinances require private streets serving 6 or more lots need to follow VDOT standards. The VDOT Geometric Design Standards for Residential and Mixed Use Subdivision Streets (GS- SSAR) Table 1 — Curb and Gutter Section (pg. B(1) -7) indicates that for a proposed road with traffic volume up to 2,000 ADT, 2011 AASHTO Green Book Chapter 5 (Page 5 -12) provides guidance as to the maximum grade. The Green Book page indicates local residential streets should be less than 15% (see attached guidance). However, the application proposes a range of uses for each block. These uses could potentially generate traffic volumes greater than 2,000 ADT. Please provide an analysis indicating the maximum anticipated traffic volume impacts for the most intense proposed uses for each proposed private road. Please reference the ITE Trip Generation Manual and the proposed Code of Development in the analysis. Rev. 1: The street network is not recommended for approval. Right -angled turns must be eliminated. There is no private or public road standard which allows this. Road D requires a turnaround. The main through -way (Road A to B) should be a public road. Alleys should be secondary access, and not used as sole access to units, such as with 11 -15. Rev.2: The road network is much improved with this revision. The public road and Roads B and C appear acceptable. Road D is conflicted. The initial portion near Avon Street Appears wide enough, but the road turns sharply and reduces to an alley. For lots 16 -26, a road is recommended, not an alley, as this is the primary access to units. The sharp turn would not meet any road standard. Albemarle County Community Development Engineering Review comments Page 2 of 3 3. Recommend a separate structural certification for proposed Stormtrap BMP. Because this is proposed under a travel way, the potential for structural collapse needs to be investigated prior to engineering recommendation for approval of this proposed stormwater management (SWM) treatment system. Rev. 1: See comment 1. Rev.2: comment not applicable to this review. 4. Recommend application include ranges of proposed uses instead of exact numbers of proposed dwelling units and commercial square footage. If approved, providing these exact numbers would become the zoning for this property and the site would be locked into potentially non - viable construction solutions without revisiting the rezoning process. Rev. 1: not relevant to engineering review. Rev.2: comment not applicable to this review. 5. Recommend dedication of right of way along Avon Street and SR 20 for public maintenance of sidewalks (or a Code statement which addresses their maintenance) and sidewalk extensions to adjacent neighboring driveways for pedestrian continuity. Rev. 1: no change. Rev.2: comment not applicable to this review. 6. Recommend adjusting proposed Block Plan on sheet 3. Please include entire proposed roadway easement width for proposed private roads or entire proposed public right of way width with phases for blocks proposed to serve specific lots. For example, please include the entire width of proposed access easement for Road "A" as part of the area proposed for Block A. Rev. 1: This road layout is not recommended for approval. See comment 2. Rev.2: comment not applicable to this review. 7. Recommend an overlot grading plan should accompany each proposed site plan due to the existing steep topography. Engineering policy is that runoff should not cross more than three lots before being collected into storm sewers. Rev. 1: The concept grading provided with the zoning plan is not recommended for approval. It does not meet the conditions of the proposed overlot grading proffer. There are areas where drainage from lot to lot will be an issue. Rev.2: The retaining walls and grading should meet the standards recently adopted in the steep slopes overlay district. This will involve a revised retaining wall layout, which may affect the plan. Albemarle County Community Development Engineering Review comments Page 3 of 3 8. Recommend proposing an active pedestrian crossing system and crosswalk across Avon Street between proposed Spring Hill Village and existing Avon Park to address pedestrian connectivity between these planned residential developments. Rev. 1: addressed. Rev.2: comment not applicable to this review.