HomeMy WebLinkAboutSUB201200027 Review Comments Road Plan and Comps. 2012-03-13� OF AL
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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: North Pointe Phase 3 Road Improvement; WPO- 2012 - 00020, SUB - 2012 -00027
Plan preparer: David Jensen, PE; WW Associates
Developer: Mr. Richard Spurzem; Neighborhood Investments — NP LLC
Owner: Violet Hill Associates c/o Great Eastern Management Company
Plan received date: 13 February 2012
Date of comments: 13 March 2012
Reviewer: Phil Custer
The Stormwater Management, Erosion and Sediment Control, and Road Plans for the North Pointe Phase 3
Road Improvements project, submitted on 13 February 2012, have been reviewed. These plans had been
previously submitted to the county about 18 months ago. Because a resubmittal was not received within 6
months of the last comment letter, the previous WPO plan was deemed withdrawn and a new review
process must be begin. The review of the road plan, which was first performed under the previous WPO
application, is now being reviewed under a subdivision application, as now required. Road plan
comments from the first letter are continued in this document. The plans can be approved after the
following comments have been addressed.
A. General Review
1. All bonds must be posted for this plan prior to the approval of the site plan for the northwest
residential area.
2. A pedestrian tunnel has been provided between Parks E and F as required by Proffer 6.1.
However, the tunnel does not appear to meet several of the VDOT standards for such facilities as
described in Appendix B of the Road Design Manual. The following modifications to the
pedestrian tunnel are necessary for approval:
a. The bottom of the culvert will need to be a non -skid "paved surface comparable to the
finish of a sidewalk." If an additional layer of material is added, the box culvert will need
to be taller to allow for a clear height of 8ft.
b. On both sides of the tunnel, a continuous handrail will be required.
c. The width of the tunnel must be "no less than 10ft."
d. Explosion -proof security lights will be needed within the tunnel. If the fixtures are placed
at the top of the box culvert, additional height will be needed to establish at least 8ft from
the bottom of the fixture to the bottom of the culvert. Please provide a photometric plan
for the light fixtures within the tunnel as well.
e. Please add a temporary gate on both ends of this tunnel so that it can be locked until both
parks have been opened to the public.
f. Please provide the following note on sheet C -9, C -16, and C -33: "At the time that Parks E
and/or F are designed and the layout for the pedestrian path using the tunnel is proposed,
the applicant shall align the pedestrian corridor such that the interior of the tunnel is
visible to pedestrians from a distance of not less than 25 ft, two sets of stairs (one on each
side of the road) will be provided from North Pointe Blvd. to the pedestrian path, and the
tunnel will be made accessible to persons with disabilities via the extension of the path to
Albemarle County Community Development
Engineering Review Comments
Page 2 of 7
the sidewalk along Northside Drive (a "circuitous route," as described in the VDOT
standards)."
A comment with the first review of this plan requested that a 1Oft shelf be graded into the road fill
slopes. The intent of this comment was to allow an area just above the culvert on the slope where
a 5ft path could be constructed without the need for another stream crossing. In this second
submittal, the 18ft tall culvert was replaced with an arch culvert with an effective height of 25ft
and a loft wide area for the path directly behind the guardrail at the top of the fill. While this
design still allows for some flexibility in the design of the path and the grading of the embankment
between the back of guardrail and top of the culvert headwall, it is not ideal and will likely require
significant grading in the future. Because the paths are not required to be constructed at this time,
the design in this respect is approvable. However, it is the county's preference that the applicants
consider the ideal location of the required path with respect to the fill slopes to limit earth
disturbance in future phases. Alternatively, two bridge stream crossings could be provided for the
paths at a later date.
B. Road Plan Review Comments (SUB- 2012 - 00027)
1. I understand that a variation request was provided to the Planning Department without any detail
of what was to be varied. The applicant's letter simply asked the Planning Department to accept
the proposed cross - sections as designed. I have reviewed the cross - sections on Sheet C -10 of this
set and compared those with the cross - sections on D1 and D2 of the application plan. I have listed
all of the discrepancies between the two plans below. If I have missed any differences, the
applicant must inform me and the Planning Department before any variation is granted.
• increasing the planting strip in the NPBS cross - section from 6ft to l lft
• increasing the planting strip in all other cross - sections, except for North Pointe Blvd. north
of the intersection and Lewis and Clark Drive east of the intersection, from 6ft to 8ft.
• decreasing the median of Lewis and Clark Drive from Sta. 28 +27.99 to Sta. 28 +37.27
from 12ft to 4ft
• increasing the sidewalk on both sides of Lewis and Clark Drive between Sta. 28 +27.99
and Sta. 28 +37.27 from 5ft to 8ft
• decreasing the median of Lewis and Clark Drive between Sta. 29 +01.27 and Sta.
30 +49.38 from 12ft to 8ft
• decreasing the planting strip on North Pointe Blvd. north of the intersection with Lewis
and Clark Drive from 6ft to 5.5ft
• decreasing the planning strip on Lewis and Clark Drive east of the intersection with North
Pointe Blvd. from 6ft to 5.5ft
A copy of my comment letter will be sent to the Planning Department for their records. For
reconsideration of this variation request please provide another letter to the Planning Department
with these listed variations and any other variation I might have missed as well as any change
requested or required by County Engineering or VDOT.
(Rev. 1) A request for a variation was provided to the Planning Department. I have received a
copy of the letter and can find no other needed cross section variations. Engineering review
has no objection to the approval of the variation.
2. Between Sta. 27 +75 and Sta. 31 +25 of Lewis and Clark Drive, the alignments of the through lanes
are not smooth and appear to connect at angles. The applicant is proposing to modify the median
from 8ft down to 4ft, up to 8ft again, and finally up to 16ft all in a span of 350ft. Please provide
curve radii and stations of the centerline of each through lane and reduce the number of median
variations the road is subjected to. I recommend maintaining the 8ft wide median to Sta. 28 +37.27
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Engineering Review Comments
Page 3 of 7
and transitioning from the 8ft median to 16ft median between Sta. 29 +01.27 and Sta. 30 +49.38.
Per the cross- section on D1 of the Application Plan, the sidewalks in the first cross - section of
Lewis and Clark Drive can be 5ft, rather than 8ft. If VDOT requires 8ft sidewalks in this section,
ROW from TMP 32 -22P will be needed or the road will need to be shifted to the northeast.
(Rev. 1) Comment has not been addressed. The transition from the 8ft median to the 16ft
median is too severe. The minimum radius for this road is 300ft and the design of the
centerline meets this number, as stated by the applicant. However, the curve as experienced by
the travel lanes is much sharper. The northbound lane has a curve with a radius of about 206ft
and the southbound lane has a curve that has a radius of about 94ft. These numbers should be
around 300ft. Also, the ROW between Sta. 27 +78 and Sta. 28 +26 measures to be 59ft, not 60ft
as shown in the cross - section. Please clarify.
3. The 50ft wide park and exercise path is shown on the road cross - section on sheet D1 of the
Application Plan and must be constructed with the roadway. Though the cross - section on D1
appears to imply that this 50ft wide section is to be placed within the ROW of the North Pointe
Blvd., it is to be a park maintained by the Homeowners Association per Sheet G. The hydraulic
calculations for the drainage system must be adjusted accordingly. It is expected that the exercise
path will be used by bicycles and pedestrians, so the trail should be designed to meet Class A Type
2 standard of the Albemarle County Design Manual.
(Rev. 1) After discussions with the Planning Department, the construction of the exercise path
does not need to be undertaken at this time. The construction of this path will be required by
VDOT due to acceptance requirements that deal with pedestrian accessibility or an agent
determination when considering a development application for an adjacent area. However,
inlet calculations should be conservative in considering the amount of land draining into the
roadway from the east.
4. The left turn lanes between Sta. 14 +44.65 and Sta. 15 +40.55 of North Pointe Blvd. are much too
short. The entrances as shown on the application plan are too close together and create many
conflict points in this area. I recommend moving the school's entrance across from the street at
Sta. 15 +62.38 and either eliminating the entrance to the clubhouse or making it a right - in/right -out.
Input from VDOT and the County Planning Department should be considered before making any
changes.
(Rev. 1) The applicant has modified the plan according to VDOT entrance requirements.
Though, it appears that the distance between the entrance at Sta. 15 +75 and Sta. 19 +71 of
North Pointe Blvd. is shorter than the required 440ft.
The revised plan may also negatively impact the school's access points off of Lewis and Clark
Drive. The entrance has been located farther east and its construction would isolate close to a
half acre of the school lot. In the application plan, one of the school entrances was located
closer to the corner so more of the lot could be used. Please move the two entrances off of
Lewis and Clark Drive as far north as the design will allow. The school entrance location off of
North Pointe Blvd. is acceptable.
5. Please expand the limits of grading to provide adequate sight distance for the school entrance. It's
much easier to perform this work now without the concern of damaging existing sidewalks or
street trees in the future. Sediment loss will also be minimized because the efficiency of the
downhill sediment basin is higher than silt fence, which would be necessary if the sight distance
was established after construction.
(Rev. 1) Comment has been addressed.
6. The R9x7 sign only works in one direction. Can a sign directing pedestrians to the left and
bicycles to the right be easily obtained? If not, alternate signage should be proposed.
(Rev. 1) Comment is no longer necessary.
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Engineering Review Comments
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7. The length of the shared use path around the school is relatively small when compared to most
other bicycle and pedestrian facilities. I anticipate a few riders will opt to stay within the roadway
since there will be available space (17ft curb to curb width). Please maintain the automobile and
bicycle lane markings through the roadway sections with the shared use path. Maintaining the 1711
curb -to -curb width for the NPBS section might have been an oversight during the rezoning of the
property. Elaine Echols had informed me that onstreet parking had been discussed around the
school when the bicycle traffic was diverted to the shared use path. This should be clarified during
the variation discussion.
(Rev. 1) Comment is no longer necessary.
8. All drainage structures deeper than 12ft must be equipped with a safety slab (SL -1).
(Rev. 1) Comment has been addressed.
9. All drainage structures with a flow drop of greater than 411, including a drop from the throat, must
use inlet shaping (IS -1). A general note on each drainage profile sheet will suffice.
(Rev. 1) Comment has been addressed.
10. Please provide a landscaping plan for the street showing ornamental plants within the median and
street trees within the buffer strip.
(Rev. 1) Proffer 5.1 states that street trees are required at a spacing no greater than 50ft. There
are several places where more trees could be added. Most significantly, street trees must be
provided along the exercise path. There is also an opportunity for 5 trees on the west side of
Lewis and Clark Drive at the school lot entrance. One tree can be provided just south of inlet
16. One tree can be provided adjacent to inlet 3.
11. After all technical comments have been addressed, the applicant must request that a road bond be
computed. To request a bond, please complete the bond estimate request form and submit it and a
$250 fee to the County Engineer.
(Rev. 1) Comment remains unchanged. All parcels will need to be party to the road bond.
12. (Rev. 1) The latest plan replaces a 48" circular culvert with an 18'x 45' arch culvert.
Generally, VDOT does not allow for culvert systems that are significantly larger than necessary
because of replacement and maintenance cost concerns. Whether the proposed arch culvert is
allowed will be a VDOT decision. If allowed, the arch culvert may be a better pedestrian access
facility compared to the 8ft box culvert. If the arch culvert is to remain in the plan, I
recommend that the applicant ask the Planning Department if the arch culvert would qualify as
the pedestrian tunnel if a trail was constructed next to the stream. It seems tome that it would
qualify if all of the VDOT pedestrian tunnel standards were met. If the arch culvert is to
remain, please also provide handrails on top of the head and wing walls of the arch culvert.
13. (Rev. 1) The drainage system along Lewis and Clark Drive has been modified. It is unclear
why the drainage system from structure 3 to structure I is as deep as it is currently proposed.
What is the reason for a 20ft deep system here? If allowed by VDOT, a much larger public
drainage easement will be needed outside of the ROW. Please refer to the drainage easement
computation found in the county's design manual.
14. (Rev. 1) Larger easements will be needed around the arch culvert and pedestrian tunnel than
those currently proposed.
C. SWM Plan Review Comments (WPO- 2012 - 00020)
1. An adjustment to the modified simple spreadsheet for Temporary Facility 3 is required. The
amount of impervious area specified in the Table on C -17 does not match the area specified on C-
18. Please clarify. Also, all grassed areas that are to be regularly maintained (buffer strips and
slopes just outside of the sidewalks) must be entered into the spreadsheet as "yards & cultivated
turf." The remainder of this review will assume that a 50% removal rate is required of Temporary
Facility 3, though the biofilter bed area may need to larger based on the outcome of this comment.
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Engineering Review Comments
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To do this, it seems that the gabion baskets could be moved towards the pipe outlet.
2. A width of 10.5ft between the 452 contour lines must be provided if a top elevation of 452.1 is
specified.
3. Move the riser to the edge of the biofilter bed so the media mix does not have to be placed around
the barrel.
4. For the area of the site draining to Stormwater Facility 10, please provide a table comparing the
total and impervious areas from this property (TMP 32 -23) assumed in the Northwest Residential
Area calculations to the total and impervious area actually draining to Stormwater Facility 10
proposed in this plan. In another column or row in this table, please identify the remaining total
drainage area and impervious square footage that can be directed to Stormwater Facility 10.
5. The maximum allowable slope on access routes to stormwater facilities is 20 %. Please revise the
grading on the gravel path. It is recommended that a path flatter than 20% is proposed.
6. Please complete a Stormwater Facility Maintenance Agreement and submit it to the county with a
$17 fee after reviewing the instructions.
7. After all technical comments have been addressed, the applicant must request that a SWM bond be
computed. To request a WPO bond, please complete the bond estimate request form and submit it
to the County Engineer. All property owners will need to sign the request form and be party to the
bond.
D. ESC Plan Review Comments (WPO- 2012 - 00020)
1. The county engineer has approved the above and beyond measures on the condition that EC -2
matting on all slopes steeper than 2:1 remains in the plan. Please add EC -2 matting on all other
2:1 slopes and include it in the additional measure list on sheet C -21.
2. In the previous review, county staff had directed the applicant to follow the County Engineer
Commentary #5 which instructed the applicant to provide a basin below the culvert. In this most
recent submittal, the applicant ignored much of this comment and provided 3 traps instead, citing
environmental concerns. It should be noted, however, that the full buildout plan for this project
shows a basin in this location. Sediment basins downstream of immense fills have a greater
success rate than a complicated series of sediment traps that often wind up being in the contractors
way and sometimes are not installed or maintained correctly. There is a risk of sediment loss and
environmental damage with the three trap proposal as well. Total sediment loss and environmental
damage would be greater if this severely compromised three trap proposal is constructed and Pond
3 is constructed inline with a future application. For this reason, the applicant's offline alternative
is not acceptable until a variation is approved to permanently remove Pond 3 from the stream. In
the applicant's variation request, a graphic showing the future SWM concept plan for the
replacement of Pond 3 (and Pond 4, if desired) that preserves the channel permanently will be
required. Otherwise, the pond/basin must be constructed with this plan.
Comments 3 through 7 have been provided on the assumption that the applicant will
request and receive a variation to remove Pond 3 offline. Comments 7 through 18 are
general comments for the whole ESC plan as well as specific comments for the remainder of
the site.
3. Please provide 4 sediment trapping measures for each corner of the crossing. Since the arch
culvert will act as a diversion during and after its installation, the sediment trapping measures on
the west side should assume most of the road grading will drain that direction.
4. Please show the grading for all sediment traps with contours labeled, so that the sizing calculations
can be checked.
5. Please combine trap 3 and sediment basin 1 and lower the embankment elevation of the sediment
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Engineering Review Comments
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basin so that most of the stream crossing runoff can be diverted to it. An embankment elevation of
432 seems to be ideal.
6. Please provide small ditches above the culvert headwalls directing runoff to one of the four
sediment trapping measures.
7. For the area around the stream crossing, please show an esc plan phase with the existing grades as
the arch culvert is being constructed. Please show stone access paths to the temporary stream
crossing and detail how the existing channel is going to be diverted away from the construction of
the arch culvert foundation. Currently, it appears as this channel is being diverted to trap 4, but
trap four is located 4ft higher than this Swale.
8. Please move the temporary stream crossing bridge to the edge of the work area. The current
proposed crossing location is not practical in that it would be unusable during many phases of
construction. Please make sure the access routes on both sides of the crossing drain to a sediment
trap or basin.
9. The installation of the temporary stream bridge crossing must occur in step 3, not step 5.
10. Please show an area for a soil stockpile on the plan. Please also update the Offsite Areas of the
narrative to match what is specified in step 8 of the construction sequence.
11. Cleanwater diversions are not an approved state erosion and sediment control measure. Please
remove all channels that are only put in the plan to limit the size of the sediment traps and basins.
Please adjust all trap and basin calculations and designs accordingly. The diversion south of the
inlet 16 appears to go uphill as well.
12. The northside of North Pointe Blvd. from Lewis and Clark Drive to the easternmost entrance to
the multifamily development must drain to one sediment trap. Diversions must replace silt fence
in this area and direct runoff from this side of the road to this trap.
13. Please supplement the site survey with the county aerial topography on Sheet C -20.
14. Construction entrances must drain to sediment trapping measures. Please provide a sediment trap
northeast of the construction entrance and have it sized for the area between the front of the
construction entrance and the RWD to trap 1. Please provide another RWD across the front of the
construction entrance. Once final grade is reach, the effective construction entrance /wash rack can
be moved uphill of the RWD to trap 1, at the discretion of the county ESC inspector.
15. Please provide a map showing the maximum drainage area to each sediment trap and basin so that
the calculations can be checked.
16. Please provide an analysis of the downstream cross - sections as irregular channels. For each
segment of the surveyed cross - section, please provide a permissible velocity (Table 5 -22) and
calculated velocity. Higher velocities are often hidden in the averaged calculations due to areas of
lower velocities in the shallow depths.
17. State law requires that downstream channel analyses be provided until the project area is I% of the
watershed of the stream. However, the 1% rule is not computed with each incremental ESC plan,
but the whole area approved in the rezoning plan. For this reason, Flat Branch to its confluence
with the Rivanna River is technically subject to review with each NP application. The North
Pointe rezoning application constitutes more than 20% of the Flat Branch watershed at the outlet
to the Rivanna River (269acres /1150acres) and becomes more influential upstream. State law also
requires that "ultimate development" conditions be used in hydrologic calculations.
Because only a small section of the project is being developed, county staff will not be as
inflexible with state law as we could be. With this ESC application, the basic elements and
backbone of a project -long MS -19 analysis, which will be updated with each subsequent phase of
the North Pointe development plan, must be agreed upon by County Engineering and all North
Pointe owners. If the applicant does not wish to comply with this offer, they must provide MS -19
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Engineering Review Comments
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calculations using ultimate development conditions and analyze the stream channel to the
confluence with the Rivanna River.
18. After all technical comments have been addressed, the applicant must request that a ESC bond be
computed. To request a WPO bond, please complete the bond estimate request form and submit it
to the County Engineer. All property owners will need to sign the request form and be party to the
bond.
EI_esc swm rp_PBC_North Pointe Phase 3 Road Improvements.doc