HomeMy WebLinkAboutSUB201100111 Review Comments Preliminary Plat 2012-03-29ALg�,��
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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: Belvedere Phase 2 — Preliminary Plat (SUB- 2011 - 00111)
Plan preparer: Mr. Scott Collins, PE; Collins Engineering
Owner or rep.: Belvedere Station Land Trust
Date received: 19 September 2011
(Rev. 1) 7 March 2012
Date of Comment: 12 October 2011
(Rev. 1) 29 March 2012
Engineer: Phil Custer
The first revision to the preliminary plat for Belvedere Phase 2 (SUB- 2011 - 00111), received 7 March
2012, has been reviewed. The plat is not ready for conditional approval and another revision to address
county comments is required.
1. Engineering review notes the following deviations from the approved application plan and Code of
Development:
-The preliminary plat shows a SWM pond, road, and lots within the 100ft wide ROW area
to be reserved for dedication of the North Free State Connector referenced in Proffer 4.2.
Because the proffer is rather explicit about this reservation, it seems to me that any change
to this requirement must be approved by the Board of Supervisors because Planning can
only modify the Code of Development and the Application Plan.
-The proposed layout of Block 8 does not match the approved application plan. A road
and stormwater facility has been added. Park H has been relocated.
- Proposed public street cross - sections within this plat do not match the application plan for
just about every roadway. Roads are often smaller than the minimum allowable in Table 8
of the Code of Development. Two way travelways have been proposed on Roads I and H
rather than one way as stipulated in the Code of Development.
The applicant must modify the preliminary plat or request a variation to the Planning Department
for the above changes. The North Free State Connector ROW issue does not appear to be variable.
(Rev. 1) A variation has been received. Engineering review notes that the applicant currently
proposes smaller widths for Streets Rand X than shown on the approved application plan. The
justification is that parking will only be allowed on one side. But Table 8 had shown parking
on both sides of the street for all two way streets. What is being requested is a deviation from
the original concept and Planning should be aware of that when considering the variations.
2. A critical slope waiver is necessary for this project. A request for critical slope waiver, as outlined
by Section 18- 4.2.5.a.1, must be provided to the agent.
(Rev. 1) A critical slope waiver request has been submitted. The analysis of which will be
provided under separate cover.
3. Please clearly show the Preservation Area as approved on the rezoning plans on all sheets. A
sanitary sewer line is proposed through the Preservation Area in at least two instances. Please
remove all construction from these preservation areas.
(Rev. 1) The Preservation area is shown as curved behind lots 97 -101, but this line is straight in
the application plan. Please show the Preservation Areas exactly as they were approved.
4. An overlot grading plan will be needed before Final Subdivision plat approval is given. The
requirements of the proffered overlot grading plan will require more disturbance in Block 9, that
may encroach upon the preservation areas or will make it difficult for erosion and sediment control
measures to be located outside of the preservation area.
(Rev. 1) The county concern with the grading around lot 100 and the ESC plan has been
acknowledged by the applicant. I expect the grading of Road D will need to be modified during
the final review of the plan to allow for the ESC /SWM plan to work in this corner of the site.
The grading plan has been modified in this latest iteration and retaining walls have been added
throughout the site. The overlot grading plan proffer specifies that no slope steeper than 2:1
may be allowed. In other projects with this same proffer, this provision has been interpreted to
mean that no retaining walls will be permitted. Please be aware that the conceptual grading
plan will need to be adjusted later to meet this requirement. (I have requested an interpretation
from the Zoning Department regarding this proffer to confirm that the interpretation above will
be maintained for this project. I will forward any response from them once it is received.)
5. Please show sight distance triangles on the grading sheet. For sight lines that travel across
roadway crests or other grading obstructions, such as northern Alley B looking east, please provide
a vertical profile of the sight line. Issues with sight distance may require significant grading
modifications or alternative road alignments.
(Rev. 1) Comment has been addressed. A more complete review, with requirements of vertical
profiles of some sight distance lines, will be performed when the road plans are submitted.
6. Please extend Alley A to the existing alley serving lots in Block 4.
(Rev. 1) Comment has been addressed.
7. Please provide a county modified simple spreadsheet for each stormwater facility and provide
some preliminary analysis for each stormwater management facility (drainage area, required
removal rate, proposed type, water quality volume, etc.). [14- 302.A.13]
(Rev. 1) The following modifications are needed to the conceptual SWMplan to receive
engineering approval for this preliminary plat:
a. For facility 1, a Type III Retention Basin is needed based on the required removal rate
computed from the modified simple spreadsheet. Please show and label an aquatic
bench around the perimeter of the facility at the water level and refer to this pond as a
Type III facility.
b. Please locate all of Stormwater Facility I out of the VDOT ROW. The 100 year water
elevation should not back up into the VDOT ROW. Also, I recommend that this
facility is conservatively sized in the preliminary plat because over - detention may be
required because of the potential of adequate channel issues with the railroad.
c. The stormwater plan for Phase 1, WPO- 2006 - 00048, originally approved by the county
in 2007 and an amendment in 2008, states that facility 4 is sized for water quantity for
phase II development, but that "[qluality control for the portion of the DA within
Phase 2 will be achieved through future (biofilter) facility #4A (to be submitted with
Phase 2 Final Subdivision Plans)." Please show a stormwater quality facility treating
the 2.47acres (though please see the following comment).
d. A sediment trap or basin will be needed behind lot 101. This facility should remain as a
SWM BMP in the post- development scenario. Please make sure this BMP is located
outside of the Preservation Area. Road D should be lowered in front of Lot 101 to
provide more room for this facility above the preservation area. Access to the BMP will
be needed from the street.
e. Please identify Stormwater Facility 1 as treating at a removal rate of 65 %.
f. Please show permanent channels from Lots 107 and 117 to facility 2. Please update the
modified simple spreadsheet accordingly.
g. A full review of the SWM plan will be performed when a WPO application is filed with
the county. It appears that the modified simple spreadsheets are underestimating the
impervious area associated with a development such as this. This will be reviewed in
greater detail later.
8. Stormwater facility 2 (located in Block 7) is not practical. VDOT will likely have an issue with it
since it will likely back up water into its pipe system. Also, the lowest escape point for water
ponding in this stormwater facility is the low point of the roadway, 448, which creates freeboard
concerns and reduces the usable volume of the pond considerably. It does not appear possible that
all stormwater management requirements can be met internal to Block 7. 1 recommend moving the
pond to the other side of Farrow Drive to avoid these issues. A sediment basin will be needed in
this location anyway. Any modification to the location of Stormwater facility 2 will need to be
approved by Planning with a variation, which, in this case, engineering will likely support,
depending on the proposal.
(Rev. 1) A variation for this change has been received by Planning. Engineering staff
recommends the approval of this variation as long as there no new Planning concerns that are
raised with this change.
9. The ADT's of the development need to take into account the projected development surrounding
these roads. For instance, Farrow Drive and other roads in this area must account for projected
traffic in Block 10.
(Rev. 1) The plan has accounted for the future traffic from Block 10 but has not included
traffic for the undeveloped parcels of land to the north and east that must travel through this
street network.
10. Label roads in this plat so that they match the names given to them during the review of the
rezoning plan.
(Rev. 1) Comment has been addressed. However, three roads have been added to the plan: X,
Y, and Z. Please refer to comment 16 for engineering concerns on road Z. Unless the
Planning Department informs me otherwise, road X and Y must meet the standards of E, F,
G... S of Table 8.
11. Please label all ROW widths in the cross - sections. Also, the roads drawn on the plan view sheets
do not match what the ROW should be when the widths are calculated from the cross - section. For
instance, for Road C the distance between face of curb and face of curb is dimensioned as 26ft
(9 +9 +8) but it is labeled on the cross - section and drawn in plan view as 24ft. Please check all
cross - sections for these mistakes. Because the cross - sections will undoubtedly be varied, please be
clear when requesting the variation what the cross section for each roadway will be. [14.302.A.5]
(Rev. 1) Comment has been addressed. Though, Planning will need to weigh in on the changes
to the widths shown in this plan.
12. A note on the cover sheet mentions the use of Private Roads. Please identify these private streets.
If private streets are proposed, this would need to be authorized by the Planning Department with a
variation.
(Rev. 1) Comment has been addressed.
13. Please identify the design speed of each roadway. The design speed of each roadway must match
Table 8 of the Code of Development unless a variation is given by the Planning Department.
Once the proper design speeds are identified, the horizontal curves will be verified. A design
speed of 20mph seems to be acceptable except for all streets except for Belvedere Blvd. and
Farrow Drive.
(Rev. 1) Please remove all references to alley design speeds. If an alley is to be designed at a
certain speed, it will need to meet VDOT requirements for that design speed. Other than Street
Z, all other design speeds appears to be appropriate. A minimum radius of 335ft is required on
Road D. Please modify the radius that is designed at 298ft. Other than Street Z, all other
horizontal curves appear to be appropriate.
14. Please update all sight distances based on the results of the previous comment. Sight distance onto
Belvedere Blvd. and Farrow Drive should be longer than 225ft unless a variation is approved by
Planning.
(Rev. 1) Belvedere Blvd. adjacent to Block I and 2 had a design speed of 35mph. This design
speed should be used in the extension. Please use a required sight distance of 390ft for all
connections onto Street Z. There are no other noticeable problems with the sight distance
shown in this version of the preliminary plat. Sight distance profiles will be required of many
of the intersections when a detailed review of the road plans is performed.
15. Please show sight distance triangles from all alleys.
(Rev. 1) Comment has been addressed.
16. The horizontal curves of Colbert Street are too small. A road with a design speed of 20mph
should use horizontal curves no smaller than 11 Oft. VDOT requirements may be stricter.
[AASHTO]
(Rev. 1) The applicant has responded to site review committee comments regarding the
construction of improvements (Street Z and SWM pond 1) in the 100ft area reserved for
dedication and the substandard horizontal curves on Colbert Street with a variation request and
a proposal to build an "intermediate" phase of the extension to the parkway. Engineering
review recommends that the county not allow the applicant to construct a temporary
neighborhood street within the 100ft ROW reserved for the parkway; this request should be
denied. The construction and use of the neighborhood street network temporarily would
significantly restrict future county staff to convert the improvements in the vicinity into a
parkway. The applicant should design Phase 2 of the development as originally intended when
reviewed by the BOS by simply reserving the ROW for the parkway and designing the
residential development independent of this significant road project.
If Road Z is essential and the Planning Department wishes to accommodate the applicant, it is
recommended that the road be designed to the final buildout conditions of the parkway. This
includes, but is not limited to, the curb -to curb width, design speed, bike lanes, access
restrictions (the application plan showed just Road G and one road to the north connecting,
though one connection at Street H, I, or Y seems more appropriate), clear zones, and 8ft
asphalt paths. I also recommend that, if this is to be allowed, that the county require the
applicant to provide a conceptual vertical and horizontal alignment of the parkway, with
grading shown in plan view, to confirm the alignment shown between roads G and Y would
work for a connections to the north and south.
Shifting the dedicated 100ft ROW east in some places to get around stormwater facility 1 is less
of a concern to engineering review as long as parkway road standards can be met and the 100 -
year storm kept outside of the road ROW. But I do need to point out if all improvements were
removed from the original 100ft ROW as intended by the application plan, VDOT and /or
county staff could design the parkway farther from the existing neighborhood as necessary.
The current design does not seem to respect the need to buffer the residential lots from this
collector road. If this is allowed, perhaps a mandatory buffer between the lots and parkway
should be required.
17. The horizontal curves of Farrow Drive are not labeled.
(Rev. 1) Please see comment 13.
18. The erosion and sediment control plan for this project will be difficult because of the topographic
challenges, preservation areas, and the railroad property (adequate channel requirements). When
preparing your variation request, I recommend thinking about how an approvable erosion and
sediment control plan can be designed. The county does not review Erosion and Sediment Control
feasibility when approving preliminM applications.
File: E2_ppt_PBC_Belvedere Phase 2 Preliminary Plat.doc