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Home My WebLink AboutSUB202000191 Review Comments Preliminary Plat 2020-12-02 (2)� AI ?"h �IRGRTF COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, Room 227 Charlottesville, Virginia 229024596 Phone (434) 296-5832 Fax (434) 972-4126 Preliminary Plat review Project: Jarmans Gap Development TW-55-77-A1—Preliminary Plat Project file number: SUB202000191 Plan preparer: Scott Collins, Collins Engineering [200 Garrett St., Suite K, Charlottesville, VA 22902, scott6d�collins-engineeringxoml Owner or rep.: James R. Jackson, Jr. / 6107 Jarmans Gap Road, Crozet, VA 22932 Plan received date: 6 Nov 2020 Date of comments: 2 Dec 2020 Reviewer: John Anderson Project Coordinator: Paty Satemye Engineering has reviewed the preliminary plat, and offers the following( for Final plat approval): 1. Proposed 4' segmented retaining wall requires: a. A building permit, b. PE -sealed design, and c. A recorded wall maintenance easement agreement between owners of Lot 4 and Lot 5. Deed bk.- pg. reference to recorded agreement is required prior to or with Final plat. Agreement may be recorded with the Final plat. 2. An approved WPO plan is required prior to final plat approval. Please submit WPO plan application at earliest convenience. a. Note: With WPO plan, extend discharge from proposed SWM facility to a natural or man-made storm conveyance system. It may not be discharge to ungraded non -defined general slope contours. Please see 9VAC25-870-66.B., Channel protection, first sentence: `Concentrated stormwater flow shall be released into a stormwater conveyance system...' This statement applies to discharge at any point, to any point. b. Recommend extend swale riprap outfall cross -contour further south along eastern edge of Lot 4 to the point it intersects an apparent defined natural channel on Lot 4. Else, it appears a permanent off -site public drainage easement across TNT 55E-03-B is required. See image below: solid blue line =possible location of riprap extension across Lot 4 (manmade conveyance) to apparent point of intersection with natural conveyance (indicated by existing contours, which then lead to stream on TNT 55E-03-B). Dash blue line = point of intersection of riprap (extension) with natural conveyance on Lot 4, with no off -site easement required. Off -site erosion /inadequate conveyance may pose recurrent or difficult -to -resolve post -construction issues. Design must convey post - developed runoff to a natural or manmade stormwater conveyance system at each point upslope of eventual, final off -site natural or manmade conveyance system. c. Provide VaRRM.x1s. 3. Engineering Review Comments Page 2 of 4 An earliest convenience. With road plan, please ensure /provide: a. Runoff to the west edge of the proposed public road from Jarmans Gap Road into the development is collected and conveyed via storm conveyance, with remnant runoff discharged directly to parcel to the west as non -concentrated sheet flow. b. LD-204, LD-229 tables, hydraulic design calculations. c. Plan /profile of storm collection /conveyance systems. d. Pavement design, projected ADT. e. DP, D,, needed to support item 3_d., above. f. CG-6 wherever runoff concentrates against curbing. Sheet 3 4. With WPO Plan, if SWM facility is designed as a swale, please ref swale design criteria, including longitudinal slope, etc. At first glance, SWM facility is oblong without clear swale length or width characteristics. It appears more nearly a simple detention basin. Please ensure proposed design nets intended water quality credits, by meeting VA DEQ Stormwater Design Criteria. 5. Revise Lot 5 lateral transit of Lot 4 to avoid proposed 4' segmented retaining wall (current design does this) to then approach Lot 4 lot line, that is, revise lateral location to run parallel with Lot 4 lot line within landward 50' of stream buffer to avoid dwelling construction conflict/s on Lot 4. Lot 5 private sanitary lateral should lie as nearly as possible to Lot 4 lot line as practical (5'-10' offset) in a private easement centered over Lot 5 lateral as it crosses Lot 4. Engineering recommends —8' offset from Lot 4 eastern lot line. This location is permissible under 17-604.A, with definition of sewage disposal system excluding lateral pipes from a dwelling unit to a publicly owned sewerage facility. An alternative location near lot line is required to allow reasonable use of Lot 4 and 5. Engineering does not object to Lot 5 sanitary lateral location that avoids proposed retaining wall and that lies as close as 5' to Lot 4 eastern lot line. Image illustrates comment: COT gi LA: 34,85o SF RA. z}Sv SF FF I O��I 0. LLm f 0 200. I I I ~ „I a I LOT m LA: u.[m5F SWMFACILITYAND / ACCESS EASEMENT PROPOSED SWM FACILITY- WATER QUALITY SWALE FOR WATER QUALITY .TO BUFFER Y TIE-IN TO EXISTING WATERLINE i I _ FROPOSEDI D' SEGMENTED RETAINING WALL 1 PROPOSEDSANITARY - �LATERAL(TYP.) I Engineering Review Comments Page 3 of 4 Engineering Review Comments Page 4 of 4 6. Lot 1: Similar to item 5: Please relocate Lot 1 sanitary sewer lateral near /within Lot 2 side setback to minimize potential future Lot 2 building site conflict/s. Provide and record a private sanitary sewer lateral easement for Lot 1, across Lot 2. Easement may be recorded with final subdivision plat. See image, below. -$ r LOT 'o LA: 33,030 SF BA: 18,97S SF CK1SyP 1 S\OCS01- 5 T � � I LOT2 )" LA:;7,763 SF / BA: ig,76; SF LA, PROPOSED ao' / BA' PRIVATE UTILITY / EASEMENT n T j zo' ua' i1/ SETBACKCK(T (TVPJ 7. Provide additional existing and proposed contour labels (with WPO /Road plans) west of proposed (development access) public road, near Jarmans Crap Road. 8. With 25' radius return ending at adjacent property line, acquire and provide copy of recorded temporary construction easement needed to construct curb, sidewalk, and proposed grade. Alternatively, furnish right - of -entry letter (ROE) or similar legally -enforceable written agreement that grants developer right to occupy adjacent parcel in areas, as needed, for temporary constructive purposes. Please feel free to call if any questions: 434.296-5832-x3069. Thank you SUB202000191 Jarman Crap Rd Devp TMP 55-77A1 PPT 120220