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Home My WebLink AboutSUB201500123 Review Comments Road Plan and Comps. 2015-07-27YlAGIl`11A County of Albemarle Department of Community Development Project: Old Trail Village Block 27 — ROAD Plans Plan preparer: Chris Mulligan, Bill Ledbetter, Raleigh Davis — Roudabush, Gale & Assoc, Inc 914 Monticello Road, Charlottesville, VA 22902, cmulligan(croudabush.com, bledbetter(a)roudabush.com, rdavisAroudabush.com Owner or rep.: March Mountain Properties LLC [1005 Heathercroft Circle, Suite 100] Dave Brockman, dave a,oldtrailvilla eg com Plan received date: 2 Jul 2015 Date of comments: 27 Jul 2015 Reviewer: John Anderson SUB2015 -00123 1. Title sheet — Revise Erosion Control & SWM Note. Phase II Erosion control is not "provided by the existing SWM bio- retention pond (Upper Ballard Pond)." Upper Ballard Pond (UBP) must be protected against all erosion and sediment impacts since it is not an ESC basin or measure. Plan notes, profiles, sequence, etc. require careful revision. Also, item #4 below. 2. Sheet 13 — Remove pipe Str. #227 from this view, or indicate when it may be installed. Also, item #4, below. 3. Recommend Str -148 (to be modified, sheet 2, Belgrove St) be relocated to final Str. 148A location (sheet 3), and that Str. 148B (34.89 LF 15" DIA HDPE pipe, sheet 9) be placed prior to placing asphalt intermediate and surface asphalt courses on Belgrove St. Str -148, approved under block 28 -29B, road plan is essentially a temporary feature that changes with this plan. This is a recommendation. Contractual obligations may prevent relocation of Str. 148 prior to asphalt placement, but if this is the case, asphalt pavement and C &G must be demolished at owner's expense to effect block 27 design. 4. Critical: Sheets 4, 6, 9 (Utility plan, Grading plan, Storm profile: Ex. #144 4230 (outfall)) reflect a post - construction stabilized condition by proposing removal of Ex. Sediment basin (see WP0201500042). This is problematic. There is possibility future development of blocks 7, 6, 26, or 35 will require trap/basin in similar location (ref. WP0201400004, sheets 3, 9, 10). Construction of structures between inlet #223 and UBP (outfall) is contingent upon complete upslope stabilization of all areas/blocks draining to Str. 4223 to ensure negligible sediment -laden runoff reaches Str. #223. Str. #223 makes direct connection with UBP, an aesthetic amenity that provides habitat and quality /quantity Mgmt. (4 X WQV) for 43± on- site /110± off -site Ac. (sheets 9, 10; WP0201400004). Revise site, road, and VSMP plans using notes, labels, details, and sequence to state that until all upslope areas requiring ESC control are stabilized (via Ex. Sediment basin approved under WP0201400004/ proposed to be modified under WP0201500042), only pipe #223A may be shown as an outfall from Str. #223 (WP0201500042, sheet 3). Str. #223 is proposed to replace Ex. Str. 156A. Note: This topic was discussed in detail in email (J. Anderson, 5/21/2015 6:46 AM) and Initial Site Plan comments, SDP201500015, 20 -May 2015, items 8, 9, 12, 13, 15, 17, 21. There is no discernible response to ISP comments. Please review ISP comments (SDP201500015) and 5/21/2015 email. and revise Final Site. Road. and VSMP plans accordingly. Please call if any questions. 5. Sheet 3 —Max spread at Str. 213 =6' (sheet 14, spread = 8.9'). Revise. 6. Sheet 5 — Remove structures #227, 228, 229 from this plan view, or indicate when they may be installed. Also, items #2, 4, above. Engineering Review Comments Page 2 of 2 7. Review ISP comment #11 — revise accordingly. Note: RP sheet 14 does not account for future development of block 7. Revise runoff coefficient "C" for inlet Str. #201, 203, 209, 211, 215. Revise storm sewer design table /calculations. Design must avoid situation seen between inlet Ex. Str. #132 and Ex. #154 where runoff CFS appears to exceed pipe capacity. 8. Revise inlet computation tables to reflect increased runoff from future impervious areas in block 7 that may reach inlets on Orion Lane. Also, #7, above. 9. Golf View Dr. /Orion Lane — Provide VC at PVI Sta. 21 +18.45 and at PVI Sta. 10 +18.00, respectively. Ref. ACDSM 7.A., which re£ review checklist/Also, road plan application checklist: "Vertical curves at all grade transitions." Required for public /private streets — please note this item is checked on Applic checklist. 10. Min. K, sag =15. Revise Orion Lane VC, PVC Sta. 13 +87.50, K =9.82. This VC is 72.24' from Int. Golf View Drive. Additional curves with K < 15 are not as distant to intersecting streets. Apply Min K values ( ACDSM) to crest/sag curves except as needed to transition 2.08% cross -grade to intersecting street grade. 11. Recommend show delayed construction of planting strip and sidewalk between Str. #223 and UBP to limit demolition required when storm runoff structures between #223 and UBP are installed, which may be much later than other improvements. Ex. Sediment basin to be modified under WP0201500042 (Amendment to WP0201400004) and shown on SUB201500123/SDP201500035 (sheet 6) will remain as both ESC and intermediate SWM control until all upslope areas are stabilized, which may be an extended period of time. 12. Replace label references to Alpha Street with Orion Lane. (Sheets 2, 3, 4, 6...) 13. Revise road grade elevation/contours at east end of Golf View Drive consistent with WP0201500042, sheet 4. Note: contours (WPO sheet 4) at end of Golf View Dr. may require revision since WPO sheet 4 must show Ex. Sediment basin (to be modified) continuing. Also, see #4. 14. Reconcile storm sewer profile Ex. #144 - #230 (outfall) with plan view. In profile view, please revise to show riprap outfall protection above rather than below Upper Ballard Pond Normal WSE = 672.60'. 15. Recommend consider inlet shaping detail relative to inlet Str. #223, which for the intermediate future, directs runoff via structure 223A to Ex. Sediment basin (ref. WP0201500042/ WP0201400004). Later, Str. #223 will direct runoff to UBP. Inlet shaping cannot do both at the same time. Contact John Anderson, Engineering Dept, if any questions. janderson2Aalbemarle.org / 434 - 296 -5832 -x3069 File: SUB201500123 -Old Trail Village block 27 RP 072715