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HomeMy WebLinkAboutSUB202100149 Correspondence 2022-03-09SHIMP ENGINEERING, P.C. Design Focused Engineering March 8, 2022 John Anderson County of Albemarle Department of Community Development 401 McIntire Road, North Wing Charlottesville, Virginia 22902 RE: Response Letter #1 for SUB202100149 HTC Area C Townhomes Road Plan - Engineering Dear John, Thank you for your review of the Road Plan for HTC Area C Townhomes. This letter contains responses to County comments dated October 19, 2021. Our responses are as follows: 1. Add detail for the yard drain structures. This has been added to the site plan, Sheet C19. This is only shown on the site plan since it is a site plan feature — as roads could be constructed without yard drains. 2. C3. a. Ensure CG-12 ramp on SW side of Zinnia Crest is entirely within public RW of Berkmar Drive. ROW dedication revised to provide this. b. Provide `No parking' signs between driveways/parking spaces where street width does not meet standards for street parking This is addressed by the addition of "No Street Parking" sign, added to the 15 mph sign post at each entrance. It will be more intuitive to alert drivers about lack of street parking, inclusive of the entire development, at each entrance, rather than clutter the planting strips with signs. c. Label lots for ease of reference. Lots labelled. d. Please revise sheet title to site layout. Revised e. Revise `ribbon curb' label to CG-7; recommend label reference CG-7 (roll top) detail on C13. Revised to roll-top curb. Roll-top is similar to CG-7 (CG-7 is most accurately called "mountable" curb & gutter), where CG-7 is mountable (ideal design for higher - speed arterials, roundabouts, and landscape islands, rUtop is designed for urban street perimeter control with dense driveway spacing. Please refer to VDOT Road Design Manual Appendix Bl: Subdivision Street Design Guide — Section 4 Subsection H: "Curb and Gutter Designs." This lists Rolltop Curb as an approved design for subdivisions. This is noted here, to address your comments 3a and 8a below. f. Trim /revise steps at two lots, Connor Drive, that encroach on existing sidewalk. Design reworked, so that steps do not encroach sidewalk. g. Road name signs cannot be located on top of stop signs. Please refer to the Road Naming Manual for locations (Part III, Section 3, Location of Post and Sign). Noted, this has been fixed. SHIMP ENGINEERING, P.C. Design Focused Engineering 3. C4. h. Add a road name sign for the Zinnia Crest and Orchid Bend intersection. Added near the northwest CG-12 ramp. i. Remove the stop sign on Orchard Bend at the Flora Bend intersection. Stop sign removed. j. Add speed limit signs at both entrances. Consistent with AASHTO, the speed limit must be posted at 15 MPH. 15 mph speed limit signs added at both entrances. k. Recreation area trail is shown passing over the yard drain. Please relocate. Trail revised to avoid conflict. a. Drive entrances do not appear to meet VDOT CG-9B geometry. Ribbon/roll-top curb cannot extend through driveways. Each driveway must have a CG-9 entrance that meets VDOT standards. Add note to this effect and show concrete entrances that match the standard VDOT detail on the plan sheets. Plans clarified. Lots with primary street frontage on private streets, and with front - load, single -car garages, (lots 34-56) are placed on the traditional County street section with typical curb and gutter, planting strip, and sidewalk. The remaining lots utilize the internal Road A & Road Bl as alleyways, and have rearload garages. For these rearload units, since the streets effectively act as alleyways, and since these units alignment creates a very high density of driveways, such that a typical CG-9B entrance would be impractical and create a wave -like concrete effect along the edge of pavement, we have specified Roll-top curb (in form, a flattened, rounded curb&gutter, designed for vehicular traverse) as the gurb and gutter treatment. As was mentioned in response 2e above, this is specifically allowed by VDOT in subdivision streets. This design has also been utilized in similar townhome developments in Albemarle County, for example, the townhomes in "Abington Place", in Hollymead Town Center, across from Shimp Engineering's plan for Block 3. Also, the Townhomes in the "Pavilions at Pantops Phase 3" feature continuous rolltop curb for the dense townhome driveways. b. Relocate 12" HDPE in conflict with structure elements for units facing Timberwood Blvd. Also, move 12" HDPE pipe along edge of end unit outside of the lot (highly recommended), or center pipe within the drainage easement at a minimum. Label this easement as a private drainage easement. This is now an 8" HDPE roof drain system. It is at the edge of the new lots. It has very shallow burial, and (along with the rest of the 8" roof drains in this development) can be excavated by hand, ie. with a shovel. As such, small drainage easements are provided. Practically speaking, the extent of maintenance activites will be flushing the drain lines using the yard drains as access points. Labelled as private drainage easements throughout. c. Linework for "new 6' drainage easement" behind Lots 34-42 isn't showing. Please turn on or add. Label this easement as a private drainage easement. This is now shown and labelled private. Please note, there is now also a 15' retaining wall maintenance easement nearly parallel to this easement. d. Label all drainage easements as being private. Provided. e. Building corner on Lot 26 appears to conflict with ACSA easement. Adjust building but also ensure 18-ft deep driveway is provided. Revised, no issues now. SHIMP ENGINEERING, P.C. Design Focused Engineering 4. C5. 5. C9. 111K4-W#1 a. Label streets for ease of reference. Labelled on C4. b. Please evaluate flow line depth at Lot 34 and lot 49 to ensure drives will not flood. 28' vertical fall between Berkmar Drive and inlet at 4 parallel parking spaces on Flora Bend poses driveway entrance flooding concern. Noted. See LD-204 spread & depth calculations, added to C16, for structure A6 — due to slope, depth & spread are not large at Lot 34 & 49. c. Evaluate Lot 50 drive entrance flow line depth. Ensure no flooding of drive entrance during design event. Noted. See LD-204 spread & depth calculations, added to C16, for structure A4 — due to slope, depth & spread are not large at Lot 34 & 50. d. Light grayscale spot elevations for several lots on Orchid Bend are inconsistent with proposed grade. Please reconcile. This has been fixed. e. Recommend spot shots, consistent with proposed grade, lots 27-56, to help ensure construction prevents drive entrances from flooding. This is provided, minimum 2% positive slope away from homes (greater than or equal to superelevated street section) achieved. f. Proposed grade on SE side of Lots 27-33 is somewhat ambiguous: stairs are shown, indicating substantial grade change, lots 30-33, a grade change that appears to require grade steeper than 3:1 at lot lines immediately adjacent to existing sidewalk. Provide linework, labels, etc. to clarify design intent. Proposed grade may not exceed 2:1 This is now detailed. a. Relocate tree at CG-12 at radius in Flora Bend to provide separation between ramp /walk and street tree. Tree moved, due to numerous site constraints, we need to provide this tree, small separation provided. b. Provide notes that requires limbing those trees at 70'R curves may obstruct Min. 95' stopping sight distance to allow travelers on travelways to safely stop for vehicles exiting unit drives. Notes added to landscaping plan. c. Label proposed grade on Lots 30-33 at existing sidewalk. If steeper than 3:1, propose permanent vegetation hardier than grass (groundcover). Note added. Grade shown on grading plan. a. Review and correct profile labels, all profiles have the same label "Storm Profile A1- AT" Corrected. b. Provide note re. compaction for pipes and structures in fill; specify compaction consistent with VDOT standards. 8" HDPE line is quite susceptible to deflection unless compaction specified. Compaction note added. 7. C12. a. Provide stopping sight distance sight lines at internal stop intersections. Provided. SHIMP ENGINEERING, P.C. Design Focused Engineering b. Show sight distance easement over lots where the sight distance line is located (Lot 27 & 28). Show on all applicable plan sheets. ROW lines slightly revised, so as this is not needed on 27 & 28. Sight distance easement labelled where needed. 8. C13. a. If C13 roll top curb detail corresponds with ribbon curb, revise ribbon curb labels (C3) to read `roll top' curb. Note that rolltop curbing is not allowed at driveway entrances. Yes, this is internally corrected — there is no ribbon curb, it is rolltop curb. As stated above (reference attached VDOT Appendix B1 sheet), this is allowed for driveways. 9. C15. a. Update all road section captions to coincide with street names assigned to roads A and B. Road section names updated. If you have any questions or concerns about these revisions, please feel free to contact me at keane@shimp-en ingi eering com or Justin@ shimp-enerneering com by phone at 434-227-5140. Regards, Keane Rucker, EIT Shimp Engineering, P.C.