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HomeMy WebLinkAboutSDP202000063 Correspondence 2022-03-22 (2)SHIMP ENGINEERING, P.C. Design Focused Engineering March 10, 2022 John Anderson County of Albemarle Department of Community Development 401 McIntire Road, North Wing Charlottesville, Virginia 22902 RE: Response Letter #1 for SDP202000063 HTC Area C Townhomes - Engineering Dear John, Thank you for your review of the Final Site Plan request for HTC Area C Townhomes. I have taken over the design of this subdivision and have done my best to provide a complete design which addresses county comments from all past submittals while accommodating the constraints provided by our homebuilder clients. These revised site plans include the actual units which are intended to be constructed. This letter contains responses to County comments dated May 14, 2020. Our responses are as follows: SDP2020-00063 .ccomniend revise FSP title to include ref. to SDP202000063. Added to cover sheet title 2. Submit Road Plan and VSMP /WPO plan applications. Road plan and WPO plan approval is required for FSP approval. These plans have been submitted. WPO plan has been approved, road plan is being resubmitted concurrently with this final site plan submittal. 3. Roads must be built or bonded for final plat approval. Noted, roads shall be bonded for approval. 4. Note: On -site SWM (if any) and public /pvt. drainage easements may be recorded with final plat. Noted, thanks. 5. 10/5/20 Shimp Engineering curb and gutter waiver request is addressed via these Engineering site plan review comments in context of design standards and ordinance (VDOT subdivision design standards, drainage manual). Engineering does not request additional width with request for CG-6 where CG-2, or roll-top, or ribbon curb may be proposed (see comments elsewhere). Curb and gutter are required by 14-410(H) for pavement stability/durability, drainage, and safety reasons. Waiver request statement reading `Curb and gutter is not needed internally along both sides of Road A and B for the purposes of helping to frame the street or for the purposes of further defining the pedestrian realm' may express a useful planning orientation, but this review reflects engineering perspective that includes pavement integrity, safety, and drainage. All areas now have curb and gutter, please note that the rolltop curb features curb and gutter, with a lower "curb" portion for ease of vehicle wheel mounting. 6. Engineering does not object to Planning authorization of Roads A, B, and C as private streets, but requests pavement design for (C18) Road A, B, C sections. Also, item 78, below. Also, please Road Design Manual Appendix B(1) Page B(1)-26 REFERENCE: VDOT APPENDIX B(1) SHEET 26, ACCESSED MARCH 10, 2022 H. CURB AND GUTTER DESIGNS The Department does not require the use of curb and gutter on subdivision streets but recognizes that it is an acceptable design alternative and preferred in high density developments. Curb and gutter designs shown in Figure B(1)-13" are appropriate for Subdivision streets. Face of Curb 4" R"2 /2" D � yy . qpp ply. gel/O�Ms,�, pp tlMY R tr se pWslCed o ,l,�lfmwum/ n K/BS Is mp/Mol/p0. 2' 6" Curb Std. CG-6 Face of Curb Invert Line r' 66. 2° R=1.5' s D � s D o s D o e D e• D s eers d �myo rr,��mvm 0 �1Df9"r,c/Gs°Ys molmo/roo. Rolltop Curb Face of Curb 4r /2 2 1r— I T • D'e • D > • D . • D'e • D' � g^W/�gWQO--C6 CV1Cf G �/amnse �0�v aeJ� m�mum/ oep� �I oil l Incbs /s molMolmC. 2' 7" Curb Std. CG-7 Left Edge of Pavemeht Ribbon Curb Slope Ht match adjacent oodwoy Slope >° ° L-° I — s2'e�1 Rlbbon Curb FIGURE B(1)-13* CURB AND GUTTER DETAILS The following notes apply to CG-6, CG-7 and Rolltop curb: 1. Curb and gutter may be precast of Class A4 hydraulic cement concrete or cast in place using Class A3 hydraulic cement concrete. 2. When used with stabilized, open -graded drainage layers, the bottom of the curb and gutter shall be constructed parallel to the slope of the sub -base courses and to the depth of the pavement but not less than the thickness shown. Rev 10/20 SHIMP ENGINEERING, P.C. Design Focused Engineering note: horizontal road design must meet AASHTO Guideline for Geometric Design of Very Low - Volume Local Roads (ADT<400). C5, block II Noted, pavement design had been included in Road Plan Submittal 1, they are now re - included with the site plan submittal. Lot 52, 53: Revise entrance geometry so that vehicle wheel path between street and parking area on lot is continuous without steering correction after passing the sidewalk. Issues with this type constrictive design have required post -construction demolition /rebuild on another project (Rivanna Village). Lots 54-60 show `straight -in' (no steering) continuous entrance -driveway design. On a different project, vehicle wheel path cut into lawn and entrance apron required widening, and relocation. This has been provided with the provision of 12' wide driveway entrances for single -vehicle driveways. 8. Show lot entrance design radii for each lot (ref. CG-9 detail, C16). Certain lots show radii graphically, Lots 36-52, for example; others do not —Lots 29-35, for example. Noted, this is now provided consistently throughout. 9. Eliminate Lot 45 drive entrance -crosswalk design, which places driveway in permanent conflict with a pedestrian crosswalk. This design should not be shown under this or any circumstance, should be abandoned, cannot be approved. Overlap (even partial, but total in this instance) between a pedestrian crosswalk and driveway brings diametrically opposed pedestrian and vehicle facilities into permanent conflict, posing extreme risk to pedestrians. A driver reversing from Lot 45, whether under poor visibility, distracted, or simply unaware, may strike a pedestrian (parent with stroller, etc.) who has every right to occupy a crosswalk with expectation of safety. Perhaps Lot 45 driveway location can be shown adjacent to Lot 44 to avoid pedestrian crosswalk conflict. Noted, a legitimate CG-12 has been added for this intersection. 10. 10. Lot 24, 2 issues: a. Driveway entrance width <12' absolute minimum. Revise to meet absolute min. entrance width. Provided b. If approaching from Conner Drive, 12' w entrance may be insufficient. Provide auto -turn at entrance to Lot 24, approaching from east/Conner Drive. Revise as needed so that vehicle wheel path does not leave paved driveway at entrance at revised min. width while at the same time not requiring drastic maneuver to opposite side of Road A in order to park at Lot 24. The entrance/driveway condition has been revised so that this is not needed. 11. Multiple (perhaps the majority) of driveway entrance widths in block II are 9'. Revise entrances and avoid driveway width <12'. Effect of design is that driveway width < 12' (which does not meet entrance requirements), similar to constraint experienced in parking lots (especially if in or next to an SUV or pickup), affords very little room to either side of a sedan, much less to either side of an SUV or pickup, to enter or exit a vehicle. A 9' wide driveway is far worse than a 9' wide parking space where pavement is continuous. A 9' w driveway means different surfaces (landscape stone, turf, uneven surface, edge) require care to navigate. Even then, risk is random; 9' is too narrow for even well-balanced drivers to use without mishap. Ave. width of a car is around 6 to 6.5 ft.; SUV, 69-79' ; pickup, 6'-8' ; pickup incl. std. mirrors, 96.8" (google). Compare with 9' (108"). Residents with pickups with std. mirrors will have, if truck is centered, a strip < 6" to edge around the mirror without stepping off the driveway. Revise to extend width at SHIMP ENGINEERING, P.C. Design Focused Engineering entrance onto lots; i.e.: 12' absolute minimum width. Note: Certain lots (3, 4, 5, all <1,275 SF lots) are provided 16' w driveways, others (z1,367, 1,379 SF) have 9' w driveways. This seems insensible. Please consider practical effects and relevant standards. Design that requires residents to enter or exit vehicles in the narrow permanent confines of a 9' driveway is deficient, given standard vehicle widths, and poses risk. If ZMA or Planning Div. has approved a 9' w driveway for these HTC Area C block H townhomes, please notify Engineering. Otherwise, please accept that entrance width for driveways should continue the absolute minimum entrance width onto lots. To argue the alternative ( <12') ends where, is unclear. 9'? 8'? 6.5'? No paved minimum? Entrance (concrete section) widths are now 12' wide. Provided driveway pavement (parking surface) is minimum 10' wide. County code only requires 9' parking width per ordinance. We can conclude that 9' is the minimum driveway width. 10' is provided here for a few reasons: 1. Ease of coordination — easy to locate the even width driveway in relation to the curb cuts 2. Allows additional paved area for practicality/access benefit for users. Anecdotally, a 10' parking width is not uncommon for existing townhomes across Albemarle County (anecdotally, I have a friend who owns a townhouse with a 10' wide driveway). I have seen no requirements for larger driveway widths (not entrance width, only width for parking a car). Since this is a consideration of practicality, I will offer a practical counterargument for a 10' driveway — this provides (10' — 6.5'/2) about 21" paved width on each side of a car, wide enough for access, and this does not count additional space for existing bordering yard, which at time of construction will be accessible. This leaves owner with option to either provide additional landscaping over a 12' driveway, or if they desire more paved area, they can certainly add pavers/brick walk for additional surface (allowed, VSMP plan calculated for 12' driveways). 12. Lot 29: Remove road name and stop sign from driveway. This has been fixed. 13. (and C18): Revise Road A, Sec. B-B to provide CG-6 where street cross -slope /x-section indicate runoff concentrates against curb. Also, revise C5. This has been fixed. 14. (and C18): Revise Road C, Sec. A -A to provide CG-6 along outer curb edge. See blue highlight, image, below, near subdivision entrance off Berkmar Drive. Revise C5 plan view ( same comment ). This has been provided. 15. (and C 18): Revise Road A, Sec. A -A to provide CG-6 where street cross -slope /x-section indicate runoff concentrates against curb. Also, revise C5. This has been provided. 16. Provide occasional dimensional width labels for sidewalk fronting Berkmar Dr., widened with this project. This has been provided. 17. Road A and B 70'R (radii) do not meet AASHTO Guidelines for Geometric Design of Very Low - Volume Local Roads (<400 ADT). Revise design to meet standards. Note: Roads A, B, C are streets not alleys and must meet VDOT /AASHTO low -volume, local road standards. (CL R =70' appears less than AASHTO Min.) SHIMP ENGINEERING, P.C. Design Focused Engineering Both roads are superelevated at 2% cross slope along these 70' radii, per these AASHTO guidelines, this is acceptable. This same scenario was present for the Eco Village Site Plan (SDP201900067) — calculations demonstrating that the 2 % superelevation for a 70' radius is copied from this project, and is included with this submittal. 18. (With road plan) Submit ADT table values for ease of comparison with VDOT /AASHTO guidelines. Provided on cover sheet(s). 19. Line of sight label on 2,259 SF recreational area is unclear. `All terrace to be limited trees must be pruned to provide the line of sight' is ambiguous. Revise text for clarity. Line of sight across Lot 28 extending toward Conner Drive appears to require an easement. Provide and label (this/other) sight line easement/s. This was ambiguous and has been clarified. Label about trees only provided where trees are within the line of sight. 20. Lots 33-35 indicate porch stairs extend across parcel lines on Conner Drive private right-of-way. Revise, or provide easement with maintenance agreement/s for portions of stairs serving units on these lots that lie within private right-of-way. These are not part of the porches, but rather part of the lead walks (common throughout Hollymead towncenter). There is no exclusion for lead walks in private right of way, thus no additional steps are necessary. 21. Label sidewalk width, Road B. Label added. 22. Label trail width in amenity /playset area. Label added 23. Provide /label retaining wall safety railing in amenity /playset area for all retaining walls given risk to children and proximity to Conner Drive (railing required even for retaining wall <4-ft. ht. at this location). Rail label added 24. (C18) Provide retaining wall safety railing detail with max. opening between vertical members < 4" — Rail detail in attached retwall design. 25. Retaining wall appears to extend across SE side of amenity /play area. Provide TW/BW labels at Lot 35 end of wall to clarify where the wall ends, and that the wall ends. Wall maintenance easement on Lot 35 is required if wall is proposed to end at lot line. Label amenity /play area trail material type, and width. C6, block III Additional detail added. Trail material noted. Due diligence design now applied to tot lot amenity area. 26. Label CG-2 (Typ.) between driveways that extends between walk and units on each lot. CG-2 only included for certain driveways. CG-2 not required by code for driveways. This indeed could present a tripping hazard and in our opinion does not provide public health or safety in this application. The vast majority of driveways in Albemarle County do not have curbing. We have revised general layout has in such a way where this is no longer of much concern. See response below for additional consideration. SHIMP ENGINEERING, P.C. Design Focused Engineering 27. Provide CG-2 at Lots 1 and 10 (end units), similar to Lots 2-9 to complete curbing at existing gaps, especially since, in these gaps, vehicle wheel path for vehicles reversing from Lot 1 and 10 driveways will tend to drift from pavement, degrade turf, and undermine pavement. Ref. HTC block 4 photo below for example of CG-2 that frames end unit driveways. This curb is provided for Lot 1, 27, and 33 with the updated design to assist in grade transition and for protection of the adjacent sidewalk. For the remaining units, we understand County Engineering's concern for driveway pavement lifespan, but we push back on this request. Our rationale is below. While curb would likely promote improved pavement lifespan, the reality is that the high majority of driveways in Albemarle County are constructed without curb without prominent/premature pavement failure, even if vehicle tires depart from paved surface. The CG-2 in your example photo seem (an interpretation) to be provided more for a grading assistance, as the adjacent grade is higher than the driveways - the curb appears to help reconcile some of the slope. For Blocks 2 & 3, at most driveways, slope is not a concern, and we think for most driveways, the framing benefit of CG-2 does not outweigh the risks. On that note, 2 scenarios if a vehicle wheel leaves the driveway: 1. with no curb: some minor damage is done to the turf (usually noticeable damage is only created in saturated condition -a divot in the wet turf) 2. with curb: the side of the wheel could be scraped against the concrete, damaging the wheel, potentially damaging car suspension, etc. a. N the wheel does jump the curb, the turf could still be damaged, same as the previous "no curb" scenario. b. Additionally, CG-2 is not designed to be mounted, so if there is a reasonable risk of vehicle tires leaving a driveway, we can assume tires will occasionally mount the curb, which means eventual damage to the curb - creating yet additional maintenance requirements. The result of this is that we think, for driveways, that the forgiveness provided by omitting curb outweighs potential benefits of a curb. Anecdotally, I am thankful that my driveway has no curb, because it is cheaper and easier to repair a tire divot in turf with a shovel and some grass seed (-$25 repair), than have an auto body repair damage to a vehicle wheel caused by a curb (potential $200+ repair). 28. New `alley name and stop sign' label appears in duplicate. Engineering commends design for emphasis on pedestrian safety, but is unsure how this will work in practicality. Drivers are not accustomed to a double stop sign, and may be confused. Block III connects with a public street. Engineering defers to VDOT, yet recommends pedestrian crosswalk striping to either side of the stamped concrete brick pattern crosswalk, with stop condition past the crosswalk at intersection with Lockwood Drive. Noted, this was a digital drafting error, and has been corrected, thank you. 29. Label radii (typ.) for CG-2 curbing at ribbon curb (CG-2 that extends between alley and units). If <15R, revise design and provide detail for a gradually sloping concrete ramp to replace CG-2 at radii, such that vehicle wheels can mount the ramp as vehicles enter driveways, and such that this section of curbing (now ramp) is more durable and may not deteriorate as rapidly due to wheel strike /multiple wheel crossings. Radii for ribbon curbing (now called Rolltop Curb) has been labelled. As was alluded to in response 27, above, and as you mentioned in this comment, CG-6 curb is not designed to be SHIMP ENGINEERING, P.C. Design Focused Engineering C7 mounted, thus we have designed the rolltop curb for the dense portion of driveways. This also avoids an undulating scenario which traditional curb would provide here, which is difficult to construct, difficult to transverse, and would appear strange in appearance. We realize this rolltop curb would be an a -typical, and perhaps unwarranted, design if there were a traditional sidewalk and landscape strip, however, since these items do not exist along this area (waiver request), we believe the rolltop curb is a better application. Note that VDOT Appendix Bl allows rolltop curb. 30. C5, C6: Provide intersection sight lines for internal intersections. 100' internal private road intersection sight distance (and stopping sight distance for radii) provided. 31. Remove hydrant from sidewalk near storm Str. A5. Hydrant moved. 32. Provide Pvt. san. easement on Lot 46 for Lot 47 owner since lateral may not be installed or accessed without easement across a portion of Lot 46. Design revised so this is not necessary. 33. Similarly, provide Pvt. san. lateral easement on Lot # /for owner of Lot #: a. 47/48 b. 51/52 c. 13/14 d. 51/52 e. 53/54 f. 58/57 g. 59/58 h. 60/59 Design revised so these are not necessary. 34. Provide Pvt. sanitary lateral for Lots 18, and 36-40. Laterals shown. 35. Relocate Pvt. san. laterals onto Lots 51 and 50. Two laterals are shown on Lot 52, none on Lot 50. Laterals fixed. 36. Recommend extend Pvt. san. sewer lateral for Lot 52 further onto lot. Lateral fixed. 37. Recommend extend Pvt. water laterals to structure side of sidewalks to minimize and avoid damage to walks during water line service connections. [ Note: walks must be acceptable prior to street acceptance.] Our drawing convention is to show water service linework only to the meters. This is to avoid clutter to plans - the private portion of laterals after meter are flexible and can be run with curves & bends as needed to best transverse the lot as dictated by site constraints and plumbers' recommendations. For this subdivision, all utilities will be installed before sidewalks, and will be adjacent to house footprints. We agree with your point, but this is not really needed here as the site contractor is already contracted to provide this. SHIMP ENGINEERING, P.C. Design Focused Engineering 38. Note: San. sewer lateral clean -outs appear problematic for attached units with laterals located in pavement, else clean -outs require traffic rated lids if CO's located in private drives. Examples: Lots 24-27. Engineering defers to ACSA. Correct, traffic -rated cleanouts will be required throughout. Note added to plans. 39. Provide private drainage easemen _Toss Lots 47-52, 54-59, and 36-45, for yard inlet systems. Provided for yard drain systems. 40. Revise New 20' Storm Sewer Esm't label to read New 20' Private Drainage Easement. Revised as requested. 41. Label 8" DIP WLs. Labelled as requested. 42. Delete concrete shading (in turf area) adjacent to CG-6 on Lot 55, 60. Linework corrected. C8 43. There may be limit on placement of hydrant behind parallel parking near Lot 60; Engineering defers to ACFR. Fire hydrant revised. 44. Shift Sir. A7 label to more nearly align with structure location. Revised as requested. 45. C7, C8: There are two A2 and two Al structures, with same labels used in both block II and III. Relabel block III drainage structures (revise labeling on C 13 profile, as well). Revise labels in Cale. report tables. Block III structures relabeled for clarity. 46. C7, C8: Show linework and provide labels to show roof leader line connection with storm system. Ensure Lots 1-10, block III, roof leader line discharge does not sheet across sidewalk and is not trapped behind CG-2 curbing, if discharge is to surface. Provided as requested. 47. Revise design: spread at inlet A6 (6.27') exceeds half lane width (5'). Also, LD-204, Cale. packet. Revised to address. 48. Label Ex. watermain size in Lockwood Drive. Provided as requested. 49. Please use conventional notation for remaining lot size (69,971.6 SF). Provided as requested. 50. Recommend extend Pvt. water laterals to structure side of sidewalks to minimize and avoid damage to walks during water line service connections. [ Note: walks must be acceptable prior to street acceptance.] See response 37, above — this will be provided, but is not explicitly shown on plans, contractor will still achieve this. SHIMP ENGINEERING, P.C. Design Focused Engineering C9 51. Revise grading behind lots 53-60 to provide a reasonably -defined channel; ensure low points at yard inlets. Runoff may not cross more than 2 lots; i.e., must be collected on 3rd lot. Revised as requested. 52. Lots 12-23: In limited turf space, provide runoff collection on every third lot (yard inlet) unless roof leader lines connect with new /ex. storm sys. Vertical fall across lots as well as ambiguity concerning roof leader lines is cause for concern. No runoff collection appears to be proposed on Timberwood Blvd side of these twelve (12) units. Revised as requested. 53. Label retaining wall, Lots 12, 13. Wall labelled. 54. Lot 12, 13 retaining wall TW /BW elevations are somewhat ambiguous. Additional elevations at either end (TW/B W at each end) would be helpful. Label clarified. This is now a short, decorative -style wall. 55. Provide % slope with flow arrow for all driveways. Noted, average slopes shown. 56. Lots 36-45, and Lots 12-13 retaining walls: Provide evidence of recorded (party) wall maintenance agreement/s, and provide wall maintenance easement on final subdivision plat. This is being worked on — we will provide this within the HOA does, required for plat approval. 57. Provide grading or spot shots to ensure there is no nuisance ponding in southmost parallel parking space (of 5 spaces) opposite Lots 4-9, Road A. Provided as requested. 58. Wherever storm runoff concentrates against curbing, provide CG-6; for example, 5 parallel spaces referenced in comment, immediately preceding. Provided as requested. 59. Provide labels that more clearly identify proposed retaining walls that extend from block II amenity space across lots 36-45. Also, if retaining walls: a. Span lot lines, they require easement and recorded (party) retaining wall maintenance agreement. Albemarle is not a party to wall maintenance agreements but needs to ensure wall maintenance agreements are recorded. Also, item 57, above. Noted, 12' wall maintenance easement is now shown, maintenance agreement will be in HOA does. b. >3' In., they require a building permit. Noted. c. >4' ht., they require sealed geotechnical design, and safety railing. Also, item 23, above. Noted, provided with this submittal. SHIMP ENGINEERING, P.C. Design Focused Engineering 60. Evaluate depth of Q10-yr event runoff, Road B, where grade indicates runoff concentrates in flow line at drive entrances to lots 36 thru 45. Ensure runoff does not enter driveways of any lot in the development. Runoff does not enter driveways (CG-9B entrance with 6" rise across entrance). LD-204 for A6 shows adequacy of runoff depth at the worst portion of Road B. Note that this road was revised to be superelevated, so now minimal runoff near entrances 34-42. 61. Provide storm runoff capture (grate/inlet) in line with CG-6 or at end of CG-6; blue -circles, image below. This is not required due to updated grading design, and provision of reverse CG-6. The minimal amount of runoff will sheetflow across superelevated road in this area. C10 62. Replace Alley B CG-2 between entrance on Lockwood Drive and intersection with back alley access to units. Runoff concentrates against curbing along both edges (entrance alley is crowned). Engineering consistently requests that design that proposes to concentrate runoff against a curb provide CG-6, not CG-2. Issue has been raised with /resolved by Albemarle County Engineer. CG-6 provided for this access route. 63. CG-6 label near 82.81' contour is confusing. It is somewhat unclear if gutter pan is to extend across paved asphalt alley entrance, or not. This has been revised for clarity. As this is now a CG-9D concrete entrance, the remaining gutter pan will smoothly transition into the entrance flow tine. 64. Provide spot elevations along outer edge of southmost bump out at face of curb to ensure that runoff internal to development that drains along Alley B to Lockwood Drive, reaches Sir. B I. Noted, this is provided by the "curb cut" in the island which leaves the existing CG-6. Thus current positive drainage is maintained. Spots added — though these match existing grade. 65. Label driveway grade, units 1-10. Average driveway grade shown. C11 66. Recent aerial imagery indicates existing landscaping /streetscape trees along Tmberwood Blvd that may relieve requirement to plant a few of the proposed street trees along Timberwood. Engineering defers to Planning. Noted, this site is very tight on street trees, so these are left to provide a buffer. C13 67. Provide B 1 to Al storm profile. Although shown partially in detail 5/C13, request profile for Sir. B 1 with complete structural information (INV out, rim, str. type, etc.). Bl to Al has been replaced with roof drain system, now shown in profile. 68. Provide label for'/2" steel plate in floor of Sir. A4, in each profile that shows Str. A4. Design revised to avoid this. 69. Show all crossing san. laterals in water profile. 8" DIP WL appears to be located 3.54' below proposed grade, and crossing water laterals may conflict /should be shown. Design revised to avoid this. SHIMP ENGINEERING, P.C. Design Focused Engineering 70. Provide profile, Sir. Cl, Berkmar Drive, since Ex. 4' DI-3B is to be replaced with new 10' DI- 3B. Provide rim elevation, replacement DI. Design revised to avoid this. Structure top no longer replaced. 71. C14: Show all crossing water laterals in san. sewer profile. Shown on profiles. 72. C 15: Revise sight line captions to read Berkmar Drive (and Road C), rather than Timberwood Blvd. Labels revised. C18: 73. Provide ribbon curb detail. Ribbon curb renamed to more descriptive, "rolltop" curb — see detail 2 Sheet C16 74. Provide CG-6 to ribbon curb transition detail. Transition note added to new detail. As you can infer from the rolltop curb detail, which has similar dimensions to CG-6, this transition will be easy to achieve, and is fairly intuitive. 75. Road A, Sec. C-C: Label CG-6, for clarity. Sections updated to match recent design changes. 76. Provide typ. amenity /play area trail section. Material selection specified, the section depth noted as "designed by manufacturer" in the plans. 77. Provide pavement design [Dr, Dp] per 2018 VDOT Pavement Design Guide for Subdivision and Secondary Roads in Virginia, required to evaluate pavement section depths and for comparison with 10/5/20 Private Street Request, item 1. [ link: https://www.virginiadot.org/business /resources/Materials/Pavement_Design_Guide_for_Subdivision_and_Secondary_Roads.pdf ] Response: this had been provided with road plans, included in this submittal for consistency. 78. CALCULATIONS (31-pg. packet d. 10/5/20 re: HTC Area C Townhomes: Block H & Block III, SWM Plan): a. HTC Area C Townhomes Block II Inlets Drainage Area Map (p. 5 of Cale. packet) i. Indicates 11 attached units fronting Berkmar Drive will discharge post -developed runoff to Sir. Cl. It is not apparent how Berkmar Drive portion of rooftop runoff will reach C 1. Roof leader lines and roof runoff may not discharge to surface and sheet across sidewalk fronting Berkmar Drive as this represents high risk of fall due to ice in winter weather, and lesser risk of challenge to permanently stabilize areas along fronts of units, if roofs discharge to splash blocks. Provide additional plan detail that indicates how development areas shown draining to Cl will reach C1 without crossing sidewalk. This is a fair point, roof drain system added to address this. ii. Similarly, provide same level of plan detail showing how roof runoff from attached units fronting Timberwood Blvd. or Timberwood Blvd. roundabout, will reach inlet structures DI, D2 without sheeting across sections of broad sidewalk, which is impermissible. Roof drains added to address. SHIMP ENGINEERING, P.C. Design Focused Engineering b. Pg. 8, LD-229: i. Revise pipe DIA, Fl-A8, or revise slope since total flow =1.29 which is nearly equal pipe capacity: 1.30cfs. Addressed with redesign. Revise pipe, A5-A4, since total flow, 7.50cfs, exceeds pipe capacity: 7.Ocfs. Addressed with redesign. c. HTC Area C Townhomes Block III Inlets Drainage Area Map (p. 12 of Calc. packet) Please see comments above re. roof runoff discharge, in this instance to Str. B 1 on Lockwood Drive. Roof leader lines may not discharge to turf areas fronting units given risk of freezing sidewalk conditions in winter. Provide additional plan detail. This is a fair point, roof drain system added to address this. d. LD-229: Check table values; possible error, total flow Al to AO, given other 2 table flow values. Addressed with redesign. If you have any questions or concerns about these revisions, please feel free to contact me at keane@shimp-en 'ngi eering com or Justin@shimp-enerneering com by phone at 434-227-5140. Regards, Keane Rucker, EIT Shimp Engineering, P.C.