HomeMy WebLinkAboutSUB200600411 Review Comments Road Plan and Comps. 2009-03-30ALg�,��
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COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project:
WPO- 2007 - 00053, Ashcroft Phase III, E &SC Plan
SUB - 2006 - 00411, Ashcroft Phase III, Road Plan
Plan preparer:
Mr. Tim Miller, PE Dominion Development Resources, L.L.C. (fax.979.1681)
Owner or rep.:
Mr. Richard L. Beyer; Liberty Land LTD (fax.977.7219)
Date received:
(Rev. 2) 05 March 2009
(Rev. 1) 04 January 2008
25 July 2007
Date of Comment:
(Rev. 2) 30 March 2009
(Rev. 1) 14 February 2008
15 August 2007
Engineer:
Phil Custer
The E &SC, SWM, and road plans for Ashcroft Phase III, received on 05 March 2009, have been reviewed.
Please note that the preliminary plat for this project is set to expire on May 2 "d 2009.
A. General review comments:
1. Please provide staff with all applicable state and federal permits.
(Rev. 1) Comment not addressed. Permits from the Army Corps and Virginia DEQ appear to
be needed for this project.
(Rev. 2) Comment has not been address. In addition to the approval for the impacts of
SWM -1, please note that the permit also needs to include the intermittent stream crossing at
Sta. 24 +75 of Meadow Crossing Trail. Also, according to the USGS map, the
impoundment shown on Lot 42 would also require approval from ACE and Virginia DEQ.
2. Please note that the county is currently in the process of updating its Design Manual [DM].
Included in a revised edition of the Design Manual are four lists of notes to be included in the
plans. Please replace the old county lists with the new lists from the Design Manual's most
recent version.
(Rev. 1) Note #13 is missing from the street list.
(Rev. 2) Comment has been addressed.
3. Please update the road and ESC plans with the final road names after they have been accepted
by emergency rescue.
(Rev. 1) Comment acknowledged.
4. The applicant has not yet submitted a SWM plan. However, at this time, staff saw that a
SWM facility is shown on the ESC and road plans dated 25 July 2007 impounding an
established intermittent stream for SWM purposes. This facility will not be permitted in this
location. There are other reasonable alternative locations for SWM facilities. These changes
need to be adequately addressed and any changes need to be shown on the next submittal of
the ESC plans.
(Rev. 1) Comment addressed. A SWM plan has been received and comments have been
provided in the pages to follow.
Albemarle County Community Development
Engineering Review Comments
Sheet 2 of 8
B. WPO- 2007 - 00053; Erosion and sediment control plan review comments:
5. Please show soil divides and descriptions on plans. [VESCH]
(Rev. I) Comment addressed.
6. Please show critical slopes on 30 scale ESC plans.
(Rev. 1) Comment not addressed. Critical slopes do not appear to be indicated on the plans.
(Rev. 2) Comment has been addressed.
7. Please provide a clear and comprehensive drainage area for each sediment trap. This could be
done on a separate sheet or on the existing plan sheets. [VESCH]
(Rev. I) Comment addressed.
8. Please label all contour lines in sediment traps. [VESCH]
(Rev. I) Comment addressed.
9. Please correct north arrow on sheet E10. [VESCH]
(Rev. I) Comment addressed.
10. In many cases where the road comes from a cut to a fill section, the grading for the ditch
disappears. Please show the grading for all roadside ditches. [DM]
(Rev. I) Comment addressed.
11. Please provide MS -19 analyses of all stormwater conveyances discharge points. Please provide
on ESC plans or with the SWM application and plans. [VESCH]
(Rev. I) Comment addressed.
12. Sediment trap calculations appear to be accurate. However, please provide information in the
table regarding the top elevation of the berm and the necessary width. It should be noted that
the H listed in the table should not be used to get the required width from Plate 3.13 -1. For
instance, trap 1's effective height is about 13' (725.5' — 712'), not 3.5ft as shown in Table
5/E11. In this instance, the applicant may request a waiver of this requirement because the
VESCH states a berm for a trap may not be above 5ft.
(Rev. 1) A variance will not be granted for the height of the trap embankments. It appears
that in all cases, the trap dimensions can be modified so the embankment is reduced to the
maximum 5ft. For instance, if the length of trap I was increased (possibly doubled), the
required width of the trap would be significantly less and would reduce the height of the
berm.
(Rev. 2) Comment has been addressed.
13. Include a construction sequence in the plan and narrative. Please provide an estimate to the
time needed to complete each step of the project. [VESCH]
(Rev. 2) An updated ESC narrative was not submitted with the latest set of plans.
14. It appears that construction operations would interfere with traffic arriving at the
pool /clubhouse. Please address this in the construction sequence. Traffic to the club house
should not drive across the construction entrance. [VESCH]
(Rev. 1) Please also indicate on the plan and construction sequence how and when Meadow
Crossing Trail from Sta. 10 +00 to 16 +00 is to be upgraded as well as how access to the
public open space (including the clubhouse) is to be handled.
(Rev. 2) Comment has been addressed.
15. Please provide a sediment trapping measure at the construction entrance. [VESCH]
(Rev. 1) Comment not addressed. A small sediment trap between the road pavement and the
culvert inlet end section should be shown on the plan. The sediment trap drainage area does
not need to be inline with the ditch and needs only to accept water from the paved wash rack.
(Rev. 2) Comment has been addressed.
16. Please provide an earthwork balance calculation on the ESC plans. [DM]
(Rev. I) Comment addressed.
Albemarle County Community Development
Engineering Review Comments
Sheet 3 of 8
17. Please show a designated area for soil stockpiling and staging on the ESC plans. Provide
adequate perimeter protection at these areas. Note B8 states that there will be no stockpile
area on site. However, Note B9 suggests that there may be a need for fill material to construct
the roadway. [VESCH]
(Rev. I) Comment addressed.
18. Silt fence will only work when placed perpendicular to sheet flow. Please adjust silt fence
along first 600ft of Meadow Crossing Trail so that it is laid parallel to the contours. [VESCH]
(Rev. I) Comment addressed.
19. Please extend diversion dike directing water into Sediment Trap 2 up to the 722 contour
elevation and eliminate the silt fences. [VESCH]
(Rev. I) Comment addressed.
20. At station 20 +00 please use diversion dike along top of the cut slope towards Silt Trap 1.
(Rev. I) Comment addressed.
21. Maintain SCC #3 to existing channel. [VESCH]
(Rev. I) Comment addressed.
22. Please show the grading needed to construct driveways where a 2:1 slope must be traversed to
gain access to the lot. [DM]
(Rev. I) Comment addressed.
23. Extend drainage easement of SCC #12 to adequate channel in case of wash out in the gully.
[VESCH]
(Rev. I) Comment addressed.
24. Silt fence north of the outlet to culvert C will not work as designed. Please provide a trap
adjacent to the outlet protection and direct a diversion into this trap. [VESCH]
(Rev. I) Comment addressed.
25. Maintain diversion dike along Crofton Woods Pointe to sediment trap 5. [VESCH]
(Rev. 1) Please show the channel from culvert F being diverted temporarily into sediment trap
ST -S. Please also show all of the proposed work in this area as well.
(Rev. 2) Comment has been addressed.
26. At the hammerhead at the end of Cedarcroft Way, please provide a culvert so that the roadside
ditch maintains a linear path. Show a defined ditch to the level spreader with grading. Before
stabilization of the drainage area, provide a diversion into trap 7. Orient the level spreader so
that it will not expel water towards the building footprint of lot 53. The building footprint for
lot 54 must be at a higher elevation that the level spreader. [VESCH]
(Rev. I) Comment addressed.
27. SCC 14 does not appear to outlet into an adequate channel. Please address MS -19 concerns.
(Rev. 1) Providing an easement down to the SWM facility will address this comment.
(Rev. 2) Comment has been addressed.
28. The silt fence protecting the fill along Cedarcroft Way between stations 12 +50 (South) and
17 +00 (North) is insufficient. Please provide a sediment trap at 11 +25 (North) and run
diversions to this trap. [VESCH]
(Rev. I) Comment addressed.
29. Near station 26 +00 on Cedarcroft Way, the diversion above SCC -17 is shown flowing up hill.
(Rev. I) Comment addressed.
30. Please revise Detail 7/E11. Please note the locations where the depth of channel required
exceeds 1.3ft as computed in the Stormwater Conveyance Calculations.
(Rev. I) Comment addressed.
31. Please show the final grading for all the driveways that cross 2:1 slopes. [Policy]
(Rev. I) Comment addressed.
32. Please revise wet storage slopes in sediment trap detail. It appears all traps use a wet storage
slope of 1:1 but the details calls for a 2:1 slope. [VESCH]
Albemarle County Community Development
Engineering Review Comments
Sheet 4 of 8
(Rev. 1) Comment addressed.
33. Additional comments may be forthcoming on the next submittal due to the required changes.
A. (Rev. 1) The maximum drainage area allowed for CIP is ]acre. Please remove this
callout for all culverts with drainage areas greater than I acre.
(Rev. 2) Comment has been addressed.
B. (Rev. 1) Please provide a safety fence (SAF) around all sediment traps.
(Rev. 2) Comment has been addressed.
C. (Rev. 1) Please provide a signs for the basins /traps stating "danger, quick sand, do not
enter. "
(Rev. 2) Comment has been addressed.
D. (Rev. 1) Some of the proposed work appears to be shown outside the limits of
disturbance.
(Rev. 2) Comment has been addressed.
E. (Rev. 1) Please clear and seed the area inundated by the 100 -year storm for both SWM
basins.
(Rev. 2) Comment has been addressed.
F. (Rev. 1) Please provide USC symbols at all proposed stream crossings.
(Rev. 2) Please provide specific instruction on Sheet E4 regarding how the culvert and
road fill is supposed to take place without working in the live stream. It appears a
temporary stream crossing (SC) is needed before the permanent culvert is placed. This
stream crossing must be specified per VESCH standards. Similarly, please provide a
USC symbol on sheet E5 and provide instruction as to how the live stream is to be
handled during the construction of SWM -1.
G. (Rev. 1) Please show the measures needed to construct the embankment and access
road to SWM Facility #2.
(Rev. 2) The new sediment trap for the access road construction is awkward. SWM -2
should be a sediment basin in the ESC stage.
H. (Rev. 1) Please provide an adequate channel from culvert H to the perennial stream.
(Rev. 2) Comment has not been addressed. An adequate channel must be proved to be
existing or one must be proposed.
I. (Rev. 2) Please provide adequate channel (MS -19) analyses for the two stream
channels below this development. For more guidance on the requirements for
downstream channel analyses, please refer to the latest edition of the Design Manual,
available online.
J. (Rev. 2) Please provide a sediment basin below Culvert D. (Please see comment 72.)
34. The Water Protection Bond Amount has not been computed at this time.
C. SUB - 2006 - 00411; Road plan review comments:
35. Please provide a drainage area sheet, with topography, that shows the entire drainage area to
each culvert. [DM]
(Rev. I) Comment addressed.
36. For drainage areas larger than 20 acres, the Rational Method is not a reliable method for peak
flow estimation. Please select another method to compute peak rates to culverts A & D and to
verify the peak flows to culvert C. (This same consideration should be applied to the sizing of
all SW conveyances and features). [VSMH]
(Rev. 1) The rational method may be used for drainage areas larger than 20 acres. Because
of the considerable differences in peak flows between the different methods, engineering
review recommends analyzing the capacity of the culverts with a reasonable average. The
diameter of culvert A needs to enlarged because of the risk of overtopping during the 25 -year
storm (the shoulder elevation for this culvert is 703.90). [DM]
Albemarle County Community Development
Engineering Review Comments
Sheet 5 of 8
(Rev. 2) I do not see where SCS method was used to calculate the culvert capacity for
Culvert A. The shoulder for this culvert is the low point of the road. The culvert diameter
in the profile and the plan view does not match the calculations.
37. Please keep outlet velocities below 15cfs. [DM]
(Rev. I) Comment addressed. Though, culvert calculations appear to have been computed
with a headwall and not end sections. There is no need to resubmit calculations because an
independent check has confirmed the pipe capacities.
38. Please provide profiles for all culverts. [DM]
(Rev. I) Comment addressed.
39. Please delineate access easement, water line easement, drainage easements, and boundary lines
with distinct line types and sizes. The lines are difficult to follow in plan view sheets. [DM]
(Rev. I) Comment addressed.
40. Meadow Crossing Trail has an ADT of above 400. Therefore, as defined by the VDOT
mountainous terrain standards, the maximum grade allowed on this roadway is 14 %. Please
adjust the profile accordingly. [VDOT] [DM]
(Rev. I) Comment addressed.
41. In the profiles of Elmcroft Circle, Cedarcroft Pointe, and Meadow Crossing Pointe, please
extend the 2% cross slope to 20ft beyond the edge of pavement of the intersected street. [DM]
(Rev. I) Comment addressed.
42. The grade through any turnaround is not to exceed 6 %. [DM]
(Rev. I) Comment addressed.
43. Please label and station intersections of roads in plan and profiles. [DM]
(Rev. I) Comment addressed.
44. Culvert B is missing in the road profiles. [DM]
(Rev. I) Comment addressed.
45. Please provide profiles for all pipes and correlating structures. [DM]
(Rev. I) Comment addressed.
46. Please provide sight distance analyses and label the available distance at all intersections. [DM]
(Rev. 1) Sight distance analysis appears to be calculated from 20ft off of the centerline of the
roadway as opposed to the centerline of the closest travel lane. Please correct and adjust
sight distance easements where necessary.
(Rev. 2) Please provide a vertical profile for the sight line from Meadow Crossing Pointe
looking left onto Meadow Crossing Trail. The embankment appears to block the sight line
at this intersection. More grading may be required.
47. Because of the varying pavement cross sections, please provide a separate table summarizing
pavement cross - sections on sheet R13 and remove any reference to characteristics of the
pavement cross - section in the typical road sections. [DM]
(Rev. I) Comment addressed.
48. The detail for Meadowcroft Trail typical section shows a 50ft wide private easement while the
plan shows a 42ft wide private easement. Please verify which is correct and revise plans
accordingly. [DM]
(Rev. 1) The plan and the detail both show a 50ft wide easement but the memo states the
applicant intends to provide a 42ft wide easement. Please clarify.
(Rev. 2) Comment has been addressed.
49. Please also note on the typical section details that all ditches will be platted under a separate
drainage easement. [DM]
(Rev. I) Comment addressed.
50. For the secondary roads, the distance the guardrail must be from edge of pavement is 7ft, not
5ft, to maintain the original shoulder width of 4ft. Please correct this on the detail on page
R13 as well as on all plan sheets. [DM]
Albemarle County Community Development
Engineering Review Comments
Sheet 6 of 8
(Rev. I) Comment addressed.
51. Please provide a guardrail at the existing culvert. [DM]
(Rev. I) Comment addressed.
52. Please show the existing culvert in the road profile. A cross drain is missing at this fill section
as well. [DM]
(Rev. I) Comment addressed.
53. Further analysis by county staff has determined that for hammerhead turnarounds, a minimum
length of 50ft for the spur (from centerline of main road to edge of pavement) is required for
emergency vehicle use. Please update all hammerheads to meet this configuration. [DM]
(Rev. I) Comment addressed.
54. Please show street signage (stop signs, speed limit signs, street signs, etc.) on road sheets.
[DM]
(Rev. I) Comment addressed.
55. Please delineate the access easement and drainage easement lines with distinct line types and
lines sizes so the lines are distinguishable from one another.
(Rev. I) Comment addressed.
56. Additional comments may be forthcoming on the next submittal due to the required changes.
A. (Rev. 1) Between Sta. 15 +00 and 17 +00 of Meadowcrossing trail, the grading on the plan
does not appear to match the profile. The LP of the road is called out as 752.83 but the
752 contour line exists at Sta. 15 +85 and Sta. 16 +92. Please verify grading of all
roadways to match sure it matches the profile.
(Rev. 2) Comment has been addressed.
B. (Rev. 1) Please extend drainage easements over ditches (proposed AND existing) to the
property line or a known perennial stream. Please note that all drainage easements will
require deeds to easement. Please contact the County Attorney's office for the latest
document and submittal instructions.
(Rev. 2) Comment has been addressed. Deeds will not be necessary because these are
all private roads.
C. (Rev. 1) The width of drainage easements over culverts must be calculated from the
formula listed in the design manual.
(Rev. 2) Comment has been addressed.
D. (Rev. 1) Please provide low maintenance groundcover on all slopes steeper than 2:1.
[DM]
(Rev. 2) Please specify the type of groundcover proposed. Acceptable types of
groundcover include those found in Table 3.37C of the VESCH. The applicant may
propose alternative plantings that are comparable to those found in this table.
E. (Rev. 1) For all EC -1 callouts, please provide a note referring the contractor to detail
10/R15.
(Rev. 2) Comment has been addressed.
57. The applicant needs to submit a Subdivision Road Bond Estimate Request.
(Rev. 2) Road bonds are only needed when a final plat is ready to be approved.
58. The applicant needs to submit a Schedule of Completion for Bonded Improvements.
(Rev. 2) Road bonds are only needed when a final plat is ready to be approved.
59. The road bond amount cannot be computed until all comments are addressed.
(Rev. 2) Road bonds are only needed when a final plat is ready to be approved.
C. WPO- 2007 - 00053; Stormwater Managment plan review comments:
60. SWM quality does not appear to be provided anywhere on site. Please address. Additional
comments may be provided on next revision due to the modification of the plan to provide
water quality treatment.
Albemarle County Community Development
Engineering Review Comments
Sheet 7 of 8
(Rev. 2) Water quality information has been provided. Comments regarding the water
quality portion of this project have been provided at the end of this letter.
61. An easement needs to be provided in Basin 1 encompassing the 100 -year flood elevation.
(Rev. 2) Comment has not been addressed. The SWM easement for Basin I needs to be
extended to cover the 100 year storm elevation.
62. Access needs to be provided to the riser structures of both facilities. Please see the design
manual for access path requirements.
(Rev. 2) Access should be provided to all new proposed forebays.
63. On sheet 2, show the drainfields and FFE's for lots 15 and 16. The lowest FFE must be at
least lft higher than 100 -year elevation in the SWM facility. Both the reserve and primary
drainfields must also be kept out of the 100 -year storm elevation and SWM easement.
(Rev. 2) Comment has not been addressed. The SWM easement for Basin I needs to be
extended to cover the 100 year storm elevation. Drainfields are still proposed within the
100 year storm elevation and must be moved.
64. The downstream slope for the embankment to SWM facility 2 must be 3:1.
(Rev. 2) Comment has been addressed.
65. Please provide adequate freeboard on SWM facility 2 for the 100 -year storm. One foot must
be provided if the embankment has an emergency spillway. Two feet must be provided if the
embankment does not have an emergency spillway. [DM]
(Rev. 2) Comment has been addressed.
66. The dam for SWM facility 2 appears to be too small based on its height. [DM, VSMH]
(Rev. 2) Comment has been addressed.
67. The embankment detail refers to a concrete cradle for the riser barrel but I cannot find the
detail included in the plans.
(Rev. 2) Comment has been addressed.
68. Please show on the plans that the access path to SWM facility 2 is to be graveled.
(Rev. 2) Comment has been addressed.
69. The detail of the riser structure of SWM -I indicates a diameter of 6ft but the calculations show
6ft. Please correct.
(Rev. 2) SWM -1 has been redesigned and this comment no longer applies.
70. The stage- storage data for SWM facility #1 appears to be incorrect. Please modify and update
calculations.
(Rev. 2) SWM -1 has been redesigned and the stage- storage data appears to be accurate.
71. Please provide a SWM facility maintenance agreement and fee for recordation.
(Rev. 2) Comment remains unchanged. An agreement is needed for parcels 78A -03 —F,
78A -1, and 78A -IA.
72. (Rev. 2) The plan does not appear to capture as much of the post- development runoff as
practicable. [17 -315A] To capture and treat as much runoff as practicable:
a. Provide a culvert from the southeast side of Cedarcroft Way at the culdesac into SCC -
19. Extend SCC -19 to meet this outfall.
b. Provide a culvert at Sta. 12 +50 of Crofton Woods Pointe that directs water from SCC -
11 to SCC -IIA.
c. Grade the access road to SWM -2 at a 24% cross slope so all of it drains to SCC -19.
d. Place a new SWM facility downstream of culvert D in the open space. It is a policy of
the County to keep facilities out of individual lots where possible. This facility should
also serve as a sediment basin during the ESC stage.
e. Convert sediment trap 10 to a SWM facility and provide roadside ditches from the
highpoint to this facility.
73. (Rev. 2) The biofilter should be sized to capture the water quality volume. If the 2.5% or
4% bed area sizing method is utilized, the depth of the ponding must be ]ft.
Albemarle County Community Development
Engineering Review Comments
Sheet 8 of 8
74. (Rev. 2) The biofilter must be planted with 3 species of trees and 3 species of shrubs. As
recommended by the VSMH, there should be between 2 or 3 shrubs for every tree planted.
75. (Rev. 2) The length of driveways entered into the Modified Simple Spreadsheet does not
appear to be realistic considering the length of some of the lots and the pattern of
development shown in previous Ashcroft phases. Also, yards must be considered in the
post- development impervious calculation.
76. (Rev. 2) Forebays for each inlet point are required on all water quality BMPS. Forebays
should be sized to meet the standard in the VSMH.
77. (Rev. 2) Please provide a permanent baffle in SWM -1 for the concentrated discharge inlet
point located adjacent to the spillway.
78. (Rev. 2) A modified simple spreadsheet for SWM -1 was not provided. This is necessary
because the 65% removal rate claimed in the calculation requires sediment forebays and an
aquatic bench. If an aquatic bench is proposed, please provide the necessary calculations
for the area /volume percentages specified in the VSMH and provide a planting plan.
79. (Rev. 2) I was not able to confirm whether the permanent pool in SWM -1 was large enough
for the drainage area because a modified simple spreadsheet for the facility was not given.
80. (Rev. 2) Time of concentration computations need to be provided for SWM -1. The use of
the SCS lag method is not appropriate for this watershed. In the culvert calculations, a
time of concentration of 19.8 minutes was computed for Culvert A. I think this is more
realistic for the watershed of SWM -1 considering the slope and soils.
81. (Rev. 2) The estimated curve numbers do not appear to be accurate. The type of soil is a
major contributing factor to the curve number estimate. It appears that close to 80% of the
drainage areas for this project have soil types of D or E. Please use the values found in the
SCS tables provided in the VSMH or VESCH. Please also provide a more detail breakdown
for the composite CN used for each facility.
82. (Rev. 2) Please move the property lines for lots 67, 68, 72, and 73 so that the lots do not
contain any portion of the wet elevation of the pond.
83. (Rev. 2) Around the water surface elevation of SWM -1, please provide a ]Oft safety bench
where one is not already provided with the natural topography.
File: E3_esc swm rp_ PBC_07 -053 Ashcroft Phase IILdoc