HomeMy WebLinkAboutSUB201400067 Review Comments Road Plan and Comps. 2015-02-11COMMONWEALTH of 'VIRGINIA
DEPARTMENT OF TRANSPORTATION
1601 Orange Road
Culpeper. Virginia 22701
Charles A. Kilpatrick, P.E.
Commissioner
February 11, 2015
Mr. John Anderson
Senior Planner
County of Albemarle
Department of Community Development
401 McIntire Road
Charlottesville, VA 22902
Re: SUB -2014-00067 Westlake Hills Phases II, III, & IV
Dear Mr. Anderson:
We have reviewed the Westlake Hill Subdivision phase II, Ill & IV Road Plans, with revisions dated 4-
14-14, 6-2-14, 8-26-14, II -3-14 and 1-28-15, as submitted by Collins Engineering, and offer the
following comments:
1. All previous review comments have been adequately addressed.
2. VDOT has no objection to the approval of the road plans as submitted.
3. Prior to commencement of construction activities, there will need to be a pre -construction
meeting for this project. Please contact this office at least 48 hours prior to a requested
pre -construction conference to schedule this meeting.
If you need additional information concerning this project please do not hesitate to contact me at
(434) 422-9894.
Sincerely,
Shelly A. Plaster
Land Development Engineer
Culpeper District
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COMMONWEALTH of VIRGINIA
DEPARTMENT OF TRANSPORTATION
1601 Orange Road
Culpeper. Virginia 22701
Charles A. Kilpatrick, P.E.
Commissioner
January 27, 2015
Mr. John Anderson
County of Albemarle
Department of Community Development
401 McIntire Road
Charlottesville, VA 22902
Re: SUB -2014 -00067
Dear Mr. Anderson:
We have reviewed the Westlake Hill Subdivision phase II, III & IV, with revisions dated 4- 14 -14, 6 -2 -14,
8 -26 -14 and 11 -3 -14, as submitted by Collins Engineering, and offer the following comments:
1. Previous comments have been addressed.
2. A CG -9 should be installed to access the SWM facility (between lots 58 & 59) as a result there
will be a conflict with storm structure 4. My apologies for the oversight during my previous
review.
If you need further information concerning this project, please do not hesitate to contact me
at (434)422 -9894.
Sincerely,
Shelly A. Plaster
Land Development Engineer
Culpeper District
COLLINS ti, *:es•,::e V..
November 3, 2014
John Anderson
Albemarle County
Department of Community Development
401 McIntire Road
Charlottesville, VA 22902
RE: Westlake Hills Phase II, III, &IV
Dear John:
Thank you for your comments dated Oct 20, 2014 on the above-referenced project. The following are
responses to the items raised in your letter and the engineering meeting:
VDOT
1. The typical section detail has been updated.
2. The yard drains are provided to intercept overland flow between the lots,to prevent excessive
runoff. This technique has been successful in our previously constructed developments.
When yard drains have not been employed, excessive runoff has created washout on private
property leading to disputes.
3. The no parking signs have been revised on Westhall Drive, as parking is allowed on both
sides of the street, but not within sight distance easements, or within 40' of curb returns.
4. Driveways may be between 12' and 24' wide. Trees and utilities have been shifted to
provided adequate space for driveway access.
Lot 60: The waterline was adjusted to allocate more driveway area, 21' at the curb line
available for the driveway.
Lot 80: Adequate space is provided, 31' at the curb line available for the driveway.
Lot 101: The waterline and street tree has been adjusted 20' available at the curb line for
the driveway.
Lot 108: The street tree has been relocated, 23' available at the curb line for the
driveway.
Lot 120: The street tree and water lateral have been adjusted, 29' available at the curb for
the driveway.
Lot 121: The street tree and water lateral have been adjusted, 14' available at the curb for
the driveway.
Lot 122: The street tree and water lateral have been adjusted, 34' available at the curb for
the driveway.
Lot 133: The street tree has been relocated, 28' available at the curb for the driveways.
5. The CG-12 detail has been revised.
6. The rim of structure 26B has been corrected to 615.3' in all locations and charts.
Please contact me if you have any questions or require any additional information in your review of this
submission.
Sincerely,
•
Scott Collins, PE
COMMONWEALTH of VIRGINIA
DEPARTMENT OF TRANSPORTATION
1601 orange Road
Culpeper. Virginia 22701
Charles A. Kilpatrick, P.E.
Commissioner
October 20, 2014
Mr. John Anderson
Senior Planner
County of Albemarle
Department of Community Development
40I McIntire Road
Charlottesville, VA 22902
Re: SUB - 2014 -00067
Dear Mr. Anderson:
We have reviewed the Westlake Hill Subdivision phase II, III & IV, with revisions dated 8- 25 -14, as
submitted by Collins Engineering, and offer the following comments:
1. As previously commented, and per the 2014 Pavement Design Guide, the minimum thickness for
the aggregate course is 6 ". Please update your typical section detail as well.
2. As previously commented, please provide an explanation for the numerous yard drains.
3. Please revisit the intersection of San Marcos Way (North) and provide additional "No Parking"
signs to ensure that the on- street parking will not impact the available sight distance.
4. Please take into consideration the driveway locations in relation to the DI's and the proposed
trees to avoid conflicts during construction. Le.: Lots 60, 80, 101, 108, 121, 122 and 133. If DI's
are shifted, i.e.: 72B to the lot line between lots 120 & 121, please provide additional spot
elevations to ensure positive drainage within the cul -de -sac.
5. Please update your CG -12 details to the latest revision.
6. Though storm structure 26B is located outside of the ROW there appears to be a typo. Please
revisit profile vs. drainage description vs. HGL computations.
If you need further information concerning this project, please do not hesitate to contact me
at(434)422-9894.
Sincerely,
Shelly A. Plaster
Land Development Engineer
Culpeper District
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COMMONWEALTH of VIRGINIA
DEPARTMENT OF TRANSPORTATION
1601 Orange Road
Culpeper, Virginia 22701
Charles A. Kilpatrick, P.E.
Commissioner
July 11, 2014
Mr. John Anderson
County of Albemarle
Department of Community Development
401 McIntire Road
Charlottesville, VA 22902
Re: SUB - 2014 -00067 Westlake Hills, Phase II, III, & IV Road Plans
Dear Mr. Anderson:
We have reviewed the road plans for Westlake Hills Subdivision, Phase II, III, & IV dated
4/14/14 with revisions dated 612114 as submitted by Collins Engineering and offer the following
comments:
1. Can lots 61 and 62 be graded such that the sewerline from MH -3 to MH -2 could be
located along the rear lot lines of lots 60 and 61?
2. What is the need for the numerous yard drains?
3. The storm sewer profiles for structures 84 to 100 and 96B to 96 are not included in the
plans.
4. I think that the trips shown on Westhall Drive may be a little low. If you add the trips
shown for Concho Lane, Lampasas Drive, and San Marcos Way, the number of trips is
631 and only 641 is shown for Westhall Drive. Increasing the number of trips likely will
not change the typical section, but the trips should be accurate.
5. Per the 2009 Pavement Design Guide, the minimum thickness for an aggregate course is
6".
6. The side of the streets that will have parking on one side only need to identify which side
parking is allowed on and "No Parking" signs will need to be provided as appropriate.
7. The limits of on- street parking on Westhall Drive need to be identified as on- street
parking will impact available sight distance.
8. Standard CD -2 cross - drains need to be provided at each sag location.
9. It appears that a standard CD -1 is required at approximately station 42 +37 of Westhall
Drive.
10. It appears that a standard CD -1 is required at approximately station 13 +75 of Lampasas
Drive.
11. It appears that a standard CD -1 is required at approximately stations 12 +00, 13 +25, and
20 +00 of Concho Lane.
12. It appears that a standard CD -1 is required at approximately stations 12 +50, 13 +25,
15 +12, 18 +37, and 21 +00 of San Marcos Way.
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COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project: Westlake Hills Phase 11,111, & IV
Plan preparer: Scott Collins; Collins Engineering [200 Garrett St., Suite K,
Charlottesville, VA 22902, scott(&collins -en in�g com]
Owner or rep.: Lickinghole Creek, LLC [P. O. Box 1467, Charlottesville VA 22902,
alan(&riverbenddev.com]
Plan received date: 16 April 2014
Date of comments: 12 May 2014
Reviewer: John Anderson
A. Stormwater Management and Mitigation Plan (WP0201400031)
1. Separate out the WPO plans. They cannot be approved as part of a road plan set.
2. Drainage areas are confusing. Drainage divides' upper boundaries should coincide with
topographical high points (see post - development, Areas IA, 4A). Downslope drainage area
boundaries are somewhat subjective, but areas included in post - development plans (and runoff
calculations) are excluded as undisturbed on ESC sheets 26 and 27. Drainage area divides should
coincide with actual existing and proposed finished grades.
Runoff from Areas I & 4A should be controlled and treated to the extent practicable. Area 4A is
controlled during construction by a sediment trap (ST I), sediment basin (SB5), and temporary
diversions. Area 1 runoff is diverted to SB1 during construction. These temporary structures are
eliminated and not replaced with permanent SWM features. Please consider permanent SWM
basin or berm structures located to avoid conflict with allowable use of lots. A berm, for example,
on the downslope (western) boundary of drainage area I may divert runoff to SWM basin 1.
Grading Plan (sheet 5A) does not reflect alteration of contours likely to occur with removal of
SB5. Show grades that result from removing SB5 (pre- existing contours will be altered).
4. Use 1 -2% existing impervious area to calculate %RR, for all drainage areas. 8% pre - development
impervious area is too high. Proposed SWM Facilities are Extended Detention (2WQV) with
phosphorus removal efficiency of 35 %, but %RR for Areas 1, 2, 3, are 47, 40, 46, respectively, so
extended detention will not provide minimum water quality pollutant removal. Once %RR is re-
calculated for Area 4 using 1 -2% existing impervious area, extended detention may not be suitable
as SWM for Area 4, as well. Extended detention is appropriate for a required removal rate of
35 %.
5. The shape of SWM Facility 2 is problematic; the area between sediment forebay and retention
basin is so narrow it constricts flow. Floor width at transition from forebay to basin is 4 -ft, which
Engineering Review Comments
Page 2 of 4
is susceptible to sedimentation and obstruction. Please use less narrow configuration for SWM
Facility #2.
6. Plan views of each SWM facility (1,2,3,4) are drawn to scale. Please furnish profile views of each
facility drawn to scale. Include entire culvert pipe (outfall). Typical sections do not reflect design
heights listed as 6, 2, 8, and 10 -ft for SWM Facilities 1, 2, 3, and 4, respectively.
7. If SWM Facilities #1, 2 appear to be constructed by down - cutting existing terrain. There are
wetlands between these two SWM facilities. Soil borings are needed for these proposed SWM
facility locations. Groundwater depth is a practical concern at each location.
8. Drainage: Please ensure the carryover at any on -grade inlet is included in downstream inlet
calculations (structure 30, for example, with carryover to structure 2813). Evaluate last on -grade
inlet or inlets with carryover located prior to sump inlets, often in cul -de -sacs, to ensure that final
roadway grades and drive entrance details allow on -grade inlet carryover to reach a point of entry
to stormwater collection system. In the case of structure 30, for example, will carryover reach
structure 28B, or will it find lower outlet at drive entrances to Lot 79, 80, or 81 (prefer no
carryover at such last on -grade inlets)?
9. Please superimpose critical slopes that appear on sheet 2 on sheets 5 and 5A to facilitate review of
proposed development on critical slopes.
10. Please ensure that spread at inlet Str. 84B (San Marcos Way) does not exceed 9 -ft, and at Str. 38
(Westhall Drive) does not exceed 10 -ft. Furnish flanking inlets upslope of structures 20 and 22 on
Westhall Drive, since spread at each inlet is > 10.2 -ft.
11. As many as 26 inlets have a calculated required throat length greater than design throat length
(sheets 19, 20). Please use engineering judgment to provide design at least equal the calculated
required throat length. There are examples of slight mismatch: 12 -ft vs. 12.06 (rate insignificant),
and greater disparity: 12 -ft vs. 14.47 -ft, for example. It is cases of greater disparity that will
benefit from design that meets calculated requirements.
12. Minor: Titles of computations (tables) on sheet 22 should reference SWM Facility #3 and #4.
Also, using a start elevation of 547.5 to model SWM Facility #1 yields negative elevations.
Should start elevation for SWM Facility #1 be 542.00 instead?
B. Erosion Control Plan (WP0201400031)
1. Separate out the WPO plans. They cannot be approved as part of a road plan set.
2. Super silt fence is proposed as single perimeter control at various locations with 160 -200 ft
upslope drainage areas. VESCH details design criteria, planning considerations, construction
specifications, and conditions where silt fence may be used, and does not recognize super silt
fence. Please eliminate reference to super silt fence wherever it occurs (at least 1,600 LF are
shown as perimeter controls measures for Drainage Areas 3, 4). Please revise design to include
measures consistent with topography, percent grade, length, acreage, and suitability per VESCH.
Silt fence should not be installed cross - contour, but on- contour with minimal rise or fall along its
Engineering Review Comments
Page 3 of 4
length. Diversion dikes and sediment traps (or basins) may be more appropriate in many locations
currently shown to be controlled with super silt fence. Request for variance is an option.
3. Please review sediment basin design. Please provide emergency spillway exit channel length
calculations or narrative supporting exit channel lengths of 2.4, 4, 4, and 15 -ft. Please explain
(narrative is okay) why sediment basin #5 does not have an emergency spillway. Revise anti -seep
collar dimensions for all 5 sediment basins (size at least 4 -ft larger than barrel diameter / VSMH,
1999, p. 5 -68). SB 1 requires 3 collars given length of barrel in saturated zone = 57.68 -ft. SB 1
upstream face slope must be 2.5:1 (or flatter) given embankment height = 12 -ft.
4. Invert in -out for three sediment basin outfall pipes is identical and does not correspond with invert
information on details; please revise invert data for SB1, 2, and 4 (sheet 27), as necessary.
5. Please draw sediment basin profiles to scale. Show actual existing contours with relative scale.
Generic section views are furnished. Existing ground is shown no higher than invert of outfall of
culverts through embankments, at base of 3:1 slope. Actual slopes are flatter. Embankment
heights are given as 6, 2, 8, 12, 6 -ft (SB 1, 2, 3, 4, and 5, respectively). Note: embankment height
of SB4 and SWM Facility #4 are not identical (SWM #4 embankment height is given as 10 -ft).
6. Show baffles on plan view details for SB4 and SB5.
7. Show soil stockpiles. Show staging areas. Identify any off -site borrow or spoils sites.
8. Minor: Titles of Erosion and Sediment Control Plans Phase I and Phase I1 are reversed (sheets 26,
27).
C. Road plans (SUB201400067)
1. Intersection of San Marcos Way and Weshall Drive does not continue the 2% intersected
cross grade for a minimum of 20' from the edge of pavement of the intersected street (ref.
Sta. 14 +03.17, San Marcos Way).
2. Furnish Route Number for Jonna Street (show on plans).
3. ACCD defers to VDOT. All streets are proposed as public roads.
4. VDOT approval is required.
D. Mitigation plans (WP0201400031)
100 -ft. stream buffer (unnamed tributary to Lickinghole Creek) appears to be different on
several sheets (4A, 26, and 32). Stream buffers should not shift from one sheet to the
next.
2. These sheets do not accurately capture installation impacts required to establish sewer line
in the vicinity of MH -11. Sheet 32 does not calculate impact for this sanitary line. These
impacts are permanent in that maintenance requires permanent, clear access to sanitary
facilities. Calculate and offset impacts to areas of stream buffer impacted by sanitary
sewer line installation (see portions of lots 61, 62, 80, and 81; sheet 32).
3. SWM basins #1 and #2 cannot be installed without impact to stream buffers. They may
be drawn to show no impact, but final grade lines that touch buffer boundaries cannot be
Engineering Review Comments
Page 4 of 4
achieved without permanent alteration of landscape within the 100 -ft stream buffer or
100 -year floodplain. Delineate a reasonable zone for construction equipment operation
and alteration or loss of vegetative cover during construction or maintenance of downslope
embankments. Show reasonable buffer and floodplain impacts on sheet 32. As drawn,
design assumes no impact more than 10 -ft downslope of top of embankment of SWM #1,
or more than 9 -ft downslope of top of embankment of SWM #2. This is unrealistic.
4. Mitigation area proposed with this plan should increase above 1.04 Acres.
E. Final Plat
None Received
File: WPO201400031-Westlake Hills- Memo - 051214
13. The proposed and finished grades shown of the station axis of the storm sewer profiles
appear to be the same.
14. The invert elevations of the outlets on the storm sewer should be added to the profiles.
15. The profile for the privately maintained storm sewer section from structure 26B to
structure 26 is mislabeled.
16. Some of the data in the Drainage Descriptions table does not match the data for the storm
sewer as shown on the profile. The most notable is the rim elevation for structure 72.
There are also minor discrepancies for structures 4, 60, and 72 and for pipes 91 and 93.
If you need additional information concerning this project, please do not hesitate to contact me at
(434) 589 -5871.
Sincerely,
Troy Austin, P.E.
Area Land Use Engineer
Culpeper District
WE KEEP VIRGINIA MOVING