HomeMy WebLinkAboutWPO202000034 Correspondence 2020-10-136P ROUDABUSH, GALE & ASSOCIATES, INC.
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October 13, 2020
Mr. David James
Department of Community Development
401 McIntire Road
Charlottesville, VA 22902
Project title: Belvedere Phase 5A
Project file number: WPO-2020-00034
Dear David,
The plans have been revised to include the second stage of construction. It has been
determined that it would simplify the approach since the parcel will only have one VSMP permit.
The second stage of construction proposes 19 single family dwellings for which a Road Plan will
be submitted in the future.
Please find attached the revised plans. The plans have been revised to address the comments
in accordance with the comments received on the VSMP Permit Plan review.
A. General
1. Cover —add "WP0202000034" under the title. (Rev.1) Addressed.
B. Stormwater Pollution Prevention Plan (SWPPP)
1. Registration statement:
a. Add 'County of Albemarle' under Section IV. E.
b. Sign & date.
(Rev.1) Addressed.
2. Please update the plan insert sheets with the approved plan sheets once
approved, prior to pre -construction meeting. (Rev.1) Comment still valid.
Response: Acknowledged, the approved plan sheets will be added to the SWPPP notebook
once we have received approval from the County.
3. Provide & complete items of the SWPPP:
a. Section 8 — Qualified personnel prior to pre -con.
b. Section 9 — Signed Certification prior to approval.
(Rev.1) Addressed.
C. Pollution Prevention Plan (PPP)
1. Update the PPP. (Rev.1) Addressed.
D. Stormwater management Plan (SWMP)
1. Sheet 13: Please address Water Quantity requirements, Part II B for those areas in
your limits of disturbance that are not being accounted for Post -Development. (Rev.1)
Not addressed. The runoff areas noted above in your disturbance must be
accounted for post -development. Show the pre -development drainage area map
for those areas and how they are accounted for in the post -development
condition.
Response: Half of all roofs will drain and discharge water towards the street where it will be
collected and conveyed to the stormwater pond. The back half of the townhouse roof and
footer/foundation drains will be connected to an 8" schedule 40 PVC pipe that will discharge into
the main storm sewer and water will be conveyed to the pond.
The single family detached lots have been specified to have splash blocks at the roof
downspouts.
The yard areas will be graded/seeded/landscaped as necessary to fully stabilize the site to
prevent concentrated flow leaving the site. (This has been added as a note on the sheets)
Thereby, not causing erosion to down gradient properties. Per Virginia Administrative Code,
9VAC25-870-66.D, the yard areas will not "cause or contribute to erosion, sedimentation, or
flooding of down gradient properties or resources" and therefore, does not require to be
"diverted to a stormwater management facility."
2. Provide 10' (min) SWM facility access easement. The access will need to be paved if
the grade is over 20%. (Rev.1) Addressed.
3. Show easement over SWM facility. (Rev.1) Addressed.
4. Sheet 14: Please verify the DA to proposed culvert is correct. Where does the area in
red drain? (Rev.1) Addressed.
Please address the runoff & Water Quantity requirements for the access road
area. Response: The temporary portion of the that connects to Belvedere Blvd will
eventually become a designed/paved road. Water quantity for that portion will be
captured with a stormwater pipe network, designed, and submitted with the Future
Phase 4 plans. The portion of the road leaving Phase 5, and extending over the Future
Phase 3 Block 10A development will be temporary. Eventually this road will connect to
Farrow Circle as depicted on the Phase 3 Block 10A Initial Site plan submitted on
August 10, 2020. The entire section of the road will be built and stabilized as soon as
possible. There is no anticipated concentrated flow leaving which would require water
quantity. Since the first submission of the VSMP, additional field survey was completed,
and the existing sediment basin behind lot 245 is shown. During construction of the
secondary access road, the existing basin will be used to serve as an erosion control
measure. (Rev.1) There must be an approved SWM plan that adequately
addresses the runoff from the disturbed area of temp. access rd. Please show the
existing or approved downstream SWM. Update the SWM narrative - Sheet 16 - to
address this area's runoff— for Water Quantity compliance.
Response: The plan has been revised to show that water quantity is met at point of discharge
#2. Please see sheet 18 for more information. The stage storage report is also included for POA
#2 with this submission. Please note that the pipe invert of the pipe is specified to be buried 3
feet to provide sufficient cover after the trap is converted to permanent conditions. For routing
purposes, the invert of the pipe can not be lowered beyond the pond bottom.
6. Pond:
Provide a sediment forebay. Follow the erosion & flood control guidelines from
VADEQ, Appx. D. (Rev.1) Addressed.
b. Provide a trash rack for riser low -flow orifice. Orifices under 3" dia. are
susceptible to clogging. Increase size or install a non -clogging orifice design.
Show detail. (Rev.1) Acknowledged. The small orifice will result in
increased inspection & maintenance. For that reason alone, please
increase the orifice size and/or come up with alternative design to meet
Water Quantity compliance.
Response: An "orifice trash rack" has been proposed for the energy balance low -flow orifice to
assist in preventing debris clogging. Please see the "Stormwater management pond conversion"
sheet 17. Per County Engineering department's advisement, the orifice hole has been increased
to 3" minimum. A "orifice sizing note" has been added to sheet 17.
c. (Rev. 1) Provide anti -vortex design for riser.
Response: The anti -vortex detail and diameter requirement (72") has been added to the
sediment basin design sheet.
d. (Rev. 1) Provide posted warning signs / fence of drowning hazard.
Response: Safety fence and warning signs has been specified on the plan for the intermediate
phases of the erosion control plan. For the final phase, warning signs to be posted off Fowler
street at the access road to the pond. Two other additional signs have also been proposed near
the pond.
7. Calculations:
a. Please use the precipitation data from NOAA Atlas 14. Based upon the site's
location these are the values below. (Rev.1) Addressed.
b. Provide the pond reports showing the discharge & velocity out of the spillway
structures. (Rev.1) Addressed.
8. Contact Ana Kilmer if you wish to move forward with the Nutrient Credit purchase.
Currently, 4.57 Ib/yr TP credit needed. (Rev.1) Acknowledged. Provide VRRM,
please email. It looks like 9.68 TP credit needed and you are showing 8.29 credits
to be purchased.
Response: Ana Kilmer has been contacted regarding nutrient purchase upon plan approval. The
nutrient credits required has changed. 8.19 pounds are required. An excel file has been emailed
to David James.
9. Record the SWM maintenance agreement. (Rev.1) Comment still applies.
Response: Ana will need to prepare the agreement prior to recordation.
E. Erosion and Sediment Control Plan
1. Sheet 3: ST-1 & ST-2 do not meet the maximum embankment height of 5'. 1 measure a
height of 10' & 6' respectively. (Rev.1) Addressed.
Sheet 4: You should have diversion going to a ST here. Response: Given that the
background has been updated with the new field topo - it is not feasible to add a
sediment trap at this portion of the plan. The existing basin will be utilized for erosion
control during the construction of the fire road. Outlet protection will be use at the outfall
of the culvert to ensure the bank is protected. (Rev.1) Silt fence is not meant to run
across contours. Provide that silt fence is applied parallel to contours at intervals
of 100 ft (max) spaced down -slope. A mud trap can be used instead of sediment
trap due to space constraints; Otherwise, work with the inspector to come up
with a solution during pre -con.
Response: Mud traps have been added and the plan has been revised.
3. Sheet 6: Add BM and MU here. (Rev.1) Addressed.
4. Sheet 10:
a. Need to also size the S.B. structures for the pre -development or
intermediate phases of construction. Response: The S.B. is sized large
enough to meet the anticipated capacity of the future development of the site.
The E&SC plan for 5B is shown on this submittal. (Rev.1) Acknowledged.
Submit a VSMP plan for 5B at a later point.
Response: This VSMP addresses both stages of construction for this development. A Road
Plan will be submitted for 5B at a later point. Water quality and quantity is being addressed for
the whole development with this plan.
b. You state that the S.B is designed to handle Belvedere 5B. You would have to
submit an E&SC plan for 5B. (Rev.1) Acknowledged.
5. Indicate the slopes 3:1 or greater where low -maintenance ground cover is required.
(Rev.1) Addressed.
6. Provide OP shape & stone size calcs (see VADEQ ESC HB Spec. 3.18). Extend outfall
protection to the bottom of pond. (Rev.1) Addressed.
7. (Rev.1) Provide anti -vortex design for S.B.
Response: Per Spec 3.14, table 3.14-D, a 48" riser requires anti -vortex device of 72". The
sediment basin sheet has been updated.
We thank you for taking the time to review these plans and trust the above adequately
addresses your comments. However, please let me know if you have any questions or require
additional information.
Very truly yours,
Riki Van-Niekerk