HomeMy WebLinkAboutWPO200800060 Review Comments Stormwater Management Plan 2008-11-20� OF AL
,. vIRGI1`IZP
COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project:
Rivanna Plaza [SDP200800090, WP0200800060]
Plan preparers:
Todd Philipp [email: tphilipp @ddrva.com]
Owner /Applicant:
Mark Green [email: markg @ecorp- real- estate.com]
Plan received date:
24 June 2008
REV 1: 8 September 2008
REV 2: 12 November 2008
Date of comments:
28 July 2008
REV 1: 23 October 2008
REV 2: 20 November 2008
Reviewer:
Jonathan Sharp
REV 1: Amy Pflaum
REV 2: Amy Pflaum
A. Final Site Plan
1. Copies of all required offsite easements must be provided prior to Final Site Plan approval. [DM]
REV 1: Comment has not been addressed, Current Development Engineering has not received
Letter of Agreement from Schewel's.
REV 2: Comment has been addressed, Current Development Engineering received Letter of
Agreement from Schewel's on 11/13/08, PDF copy has been saved in network file.
2. VDOT approval is required [DM]
REV 1: Comment has been addressed, Current Development Engineering has received
confirmation on VDOT that the project has been approved.
Proposed slopes steeper than 3:1 require low maintenance (not grass) ground cover specified on
the plans. [DM]
REV 1: Comment has been addressed, see Sheet 6, Landscape Plan.
4. Guardrail with VDOT designations is required for retaining walls next to parking areas or
travelways. [ 18- 32.7.2]
REV 1: Comment has been addressed in most areas, however, Engineering is concerned that a
guardrail may be necessary at the corner of the bank drive -thru. Alternatively, a traffic
sign advising of the sharp turn may be installed. The requirement of guardrail or sign
will be at the discretion of the County Zoning Inspector once site is constructed.
REV 2: Comment has been noted.
All proposed drainage /access /water /sewer easements must be approved prior to Final Site Plan
approval. [DM]
REV 1: Proposed easements are shown on SUB200800263 Boundary Line Adjustment Plat.
Please submit necessary deeds for County review.
REV 2: Comment has not been addressed, Current Development Engineering has not received
deeds for County review. Deeds are to be submitted to County Planner.
Albemarle County Community Development
Engineering Review Comments
Page 2 of 6
6. The sanitary sewer line easement near `B" should extend to both property lines (the line to
Kegler's and the line to the daycare). [18- 32.7.4, 32.7.5.2]
REV 1: Comment has been addressed by the Boundary Line Adjustment (SUB200800263)
vacating the internal property line.
The drainage line 14 -15 requires an easement (at a minimum extending to the property line). [18-
32.7.4]
REV 1: Comment has been addressed by the Boundary Line Adjustment (SUB200800263)
vacating the internal property line.
The Contech Stormwater System is required to be placed in an easement. [ 18- 32.7.4, 32.7.5.2]
REV 1: Easement has been shown on the Site Plan and the Boundary Line Adjustment Plat
(SUB200800263). Please submit the deed for County review.
REV 2: Comment has not been addressed, Current Development Engineering has not received
deeds for County review. Deeds are to be submitted to County Planner.
9. Drainage easements must adhere to the following criteria (and no less than 20' wide): 10' + (pipe
diameter) + 2' + 2 * (depth of pipe — 5'). [DM, 18- 32.7.4, 32.7.5.2]
REV 1: Comment has been addressed, Engineering has approved the easement widths as shown
on this Site Plan.
10. No structures or trees can be placed within drainage easements. [DM, 18- 32.7.4, 32.7.5.2]
REV 1: Comment has been addressed, Engineering has approved small to medium sized
landscape features in the easements.
11. Parking cannot exceed 5% grade, in any direction. [18- 4.12.15b]
REV 1: Comment has been addressed.
12. Travelway grade cannot exceed 10 %. [18- 4.12.17a]
REV 1: Comment has been addressed.
13. Engineering requires a turn - around for the parking area directly adjacent to the daycare center.
Safety is a concern. [18- 32.7.2]
REV 1: Comment has been addressed, turn - around has been added.
14. Pavement design calculations are required for the proposed Rte. 29 turn lane improvements.
REV 1: Comment has been addressed, VDOT has provided pavement section.
15. A dumpster pad detail is required, with the following minimum specifications: 4' base stone, 6"
concrete of 3000 psi at 28 days, reinforced with wire reinforcing or #4 bars at 12" on center. [18-
4.12.19, DM]
REV 1: Comment has been addressed, detail added to Sheet 10 of the Site Plan.
16. Typical retaining wall details are required on the plans. A typical manufacture's drawing for
segmental block walls, or VDOT reference, is acceptable, with any applicable safety railings or
guardrail shown. [DM]
REV 1: Comment has been addressed, detail added to Sheet 11 of the Site Plan.
Albemarle County Community Development
Engineering Review Comments
Page 3 of 6
17. Roof drains are required to be shown on the plans, tying into the appropriate drainage structure.
[18-32.6.6d.31
REV 1: Comment has been addressed.
18. Albemarle County general construction notes and general construction notes for streets are
required to be shown on the plans. [DM]
REV 1: Comment has been addressed, notes added to Sheet 2 of Site Plan.
19. In many instances, spot elevations denoting top of curb (TC) are confusing or incorrect. For
example, many of the top of curb elevations are directly on top of parking contours and match
exactly, when there should be 0.5 foot difference for curb height. [I 8-32.6.6h.4]
REV 1: Comment has been addressed.
20. Please provide CG -12 for the sidewalk on both sides of the new entrance to Schewel's furniture
(currently CG -12 is only shown on one side).
REV 1: Comment has been addressed.
21. Engineering recommends reconfiguring drainage structure 15. As designed, drainage is very close
to overtopping the curb during the 10 year storm (D/H is 0.98), and the grading configuration for
the parking area draining to the structure is awkward and more than likely will not be implemented
correctly in the field.
REV 1: Comment has been addressed.
B. Stormwater Management Plan
22. The County currently does not have any design criteria in place for "treatment train" stormwater
quality designs. However, as shown, the proposed "treatment train" design appears acceptable.
Approval of the design for the proposed plans does not ensure that the design concepts or
methodologies will work for future "treatment train" designs. Each "treatment train" design is
reviewed on a case -by -case basis by Engineering.
REV 1: Comment noted.
23. No calculations have been provided to show that detention has been met. At a minimum, the
following must be provided: [17 -314]
• Reference to the allowance of development on TMP's 45 -112C1 and 45 -109 up to a
rational method C value coefficient of 0.75 based on the `Berkmar Drive North Extension
Existing Kegler's Detention Basin Stormwater Analysis, Jack Kelsey, March 30, 1994"
and `Berkmar Drive North Extension drainage map (3/30/94)."
REV 1: Comment has been addressed, added to Erosion & Sediment Control narrative.
Composite coefficient computations for TMP's 45 -112C1 and 45 -109 showing that the
rational method C value coefficient is not in excess of 0.75.
REV 1: Comment has been addressed, proposed C -value has been calculated at 0.72, less than
0.75 that was assumed for design of the " Kegler's Basin ".
• Computations to show that the peak rate of runoff for the 2 and 10 year storm on the
Schewel's site is not increasing.
REV 1: Comment has been addressed, impervious area on Schewel's site has been reduced,
therefore, peak flow is not expected to increase.
Albemarle County Community Development
Engineering Review Comments
Page 4 of 6
24. Please provide adequate details for each WQ facility (each Filterra, the Stormfilter system, and the
hydrodynamic separator). For the proposed Filterras, a detail of each Filterra with appropriate
inverts and piping in conjunction with their adjacent inlets must be shown. For the hydrodynamic
separator and stormfilter vault, the design configuration and all appropriate invert elevations and
piping must be shown. [DM]
REV 1: Comment has been addressed. Design information on the Contech Stormfilter and
Hydrodynamic separator prepared by Contech has been included in the Water Quality
Analysis dated June 3, 2008. Details are also provided on Sheet 11.
25. Albemarle County general stormwater notes are required to be shown on the plans. [DM]
REV 1: Comment has been addressed, see Sheet 2 of the Site Plan.
26. Copies of manufactures' approval for the Contech facilities and Filterra facilities are required prior
plan approval. [DM]
REV 1: Manufacturer's approval has been submitted by Contech for the Stormfilter and
accessories. Please submit manufacturer's approval from Americast for the 3 Filterra
units.
REV 2: Comment has been addressed, Manufacturer's approval has been submitted by Americast
for the Filterra units.
27. A stormwater facility maintenance agreement and appropriate $17 fee is required. [ 17 -304E]
REV 1: Comment has been noted.
REV 2: Maintenance agreement that was submitted 11/12 needed revision (notarized signatures).
28. A SWM bond will be computed by the County once the plans have been approved.
REV 1: Comment has been noted.
C. Erosion and Sediment Control Plan
29. The "stormwater runoff considerations" in the narrative is incorrect. [DM, VESCH]
REV 1: Comment has been addressed.
30. The phasing plan in the ESC narrative contains three phases, and the ESC plans only show two
phases. Also, the phasing plans and sequence in the narrative do not appear to correlate. [DM,
VESCH]
REV 1: Comment has been addressed.
31. The ESC plans should provide access to Kegler's at all times. Based on the narrative sequence and
plans, it difficult to tell if the new access to Kegler's will be constructed prior to the closure of the
existing access. [DM, VESCH]
REV 1: Comment has been addressed.
32. The proposed construction entrance is in the way of construction and grading activities. A more
suitable location would be off of one of the existing entrances (preferably the Kegler's entrance).
[DM, VESCH]
REV 1: Comment has been addressed.
33. Dust Control (DC), Temporary Stabilization (TS), and Permanent Stabilization (PS) symbols are
required to be shown on the plans. [DM, VESCH]
REV 1: Comment has been addressed.
Albemarle County Community Development
Engineering Review Comments
Page 5 of 6
34. A staging and parking area, and a stockpile location is required. [DM]
REV 1: Comment has been addressed.
35. Protection must be provided during all phases of construction. Erosion control measures cannot be
in the way of grading or improvements. The proposed sediment traps are shown in areas of
proposed grading, buildings, and improvements. [DM, VESCH]
REV 1: Comment has been addressed.
36. Adequate channels [MS -19] must be provided for the site. It appears that MS -19 may be addressed
upon the approval of Northtown Center, the proposed development directly downstream Rivanna
Plaza, on the other side of Rte. 29 (as the channels downstream of Northtown Center are
inadequate and they are currently proposing to making downstream channel improvements).
Otherwise, channels downstream of Rivanna Plaza must be adequate until the drainage area of the
watershed is 100 times greater than the proposed development, or until the channel reaches the
Rivanna River floodplain (whichever comes first). [MS -19, VESCH]
REV 1: The Rivanna Plaza site is upstream of the " Carrsbrook Channels ". It has been determined
that the Carrsbrook Channels are currently inadequate to carry developed flows. The
developer of Northtown Center has agreed to upgrade these channels upon development
of the site, contingent on receiving the necessary easements from Carrsbrook property
owners. If the Northtown Center site is not developed, the Carrsbrook Channels remain
inadequate. The developers of all properties upstream of these channels will have the
same responsibility. Please add the following note onto the Erosion & Sediment Control
Plan to satisfy the requirements of MS -19:
The applicant shall restore the channel from the property line of TMP 45C- 01 -OP -9 to the permanent pool of
the first Carrsbrook Pond on TMP 4561- 01 -0A -4 as a compromise solution for meeting MS19 "Adequate
Channels" (the "Restoration "). The applicant will excavate the channel to the profile designed by Albemarle
County Engineering and to be provided to the applicant. The routing of the channel will follow the natural
course of the stream to the best extent possible. A detailed route will be provided for the County's review and
approval prior to commencement of channel restoration. In the event the County would like to modify the
route, the applicant agrees to route it as directed.
The above agreement requires the applicable permits from DEQ /ACOE, as well as permission or easements
from the property owners affected by the restoration. The applicant shall request permission from the affected
land owners upon issuance of the first Certificate of Occupancy for Rivanna Plaza. Once permission is
granted by all affected property owners the applicant shall have the route designed and submitted for approval
by the County. Upon approval of the stream routing, the applicant shall apply for and obtain all necessary
DEQ and ACOE permits. The applicant shall also submit a plan for stream diversion while the work is being
performed for approval by the County. The applicant will seek permission from the affected land owners for a
time period that starts at issuance of the first Certificate of Occupancy and extends for two years after the first
Certificate of Occupancy is granted for the site. If permission from all affected land owners is not obtained
within that time frame the applicant shall not be required to restore the channel. If permission is granted by all
affected land owners, but DEQ /ACOE will not permit the work, the applicant cannot, through no fault of their
own, perform the restoration.
This condition shall expire at a time 2 years after the Northtown Center development is granted its first
Certificate of Occupancy. The County and applicant acknowledge that the Northtown Center developer has
agreed to a similar condition to satisfy the requirements of MS -19 (the "Northtown MS -19 Condition ") and will
be required to perform the Restoration in the event the Northtown project proceeds as planned. If the
Northtown developer satisfies the Northtown MS -19 Condition, the foregoing Restoration condition shall not
apply to applicant.
Albemarle County Community Development
Engineering Review Comments
Page 6 of 6
Prior to reaching the Northtown site and Carrsbrook Channels, Rivanna Plaza drains through an
existing 54" storm sewer pipe under Rte 29. Calculations need to be provided verifying that this
pipe is large enough to handle the routed 10 -year critical storm produced by the developed basin.
Please demonstrate how the 80.7 cfs from the existing Kegler's basin was calculated.
REV 2: New language has been added to the plans. Calculations for the 54" pipe under Rte 29
have been submitted.
37. An ESC bond will be computed by the County once the plans have been approved.
REV 1: Comment has been noted.
The Erosion & Sediment Control and Stormwater Management Plans (WPO200800060) have received
Engineering Review and meet Albemarle County minimum checklist items for approval. Please submit 4
paper copies of each of the E &SC and SWM plans to Current Development Engineering.
County staff will calculate the E &SC and SWM bond amounts and those figures will be forwarded
to you by Wednesday, November 26, 2008. The forms and instructions to post the Water Protection
Ordinance Bond can be found on the Community Development Department Web site on
www.albemarle.ora.
A completed copy of the Standard Stormwater Maintenance Agreement and fee for recordation for the
stormwater facilities is required prior to final approval. [17-304E] The forms and instructions can be found
on the Community Development Department Web site on www.albemarle.orc.
You may contact Pam Shifflett (Albemarle County Department of Community Development) at ext. 3246
for further information on bonding procedures and Maintenance Agreements.
Once the E &SC bond and the SWM bond have been posted, the Easement Deeds (Comments #5 & #8)
have been reviewed and accepted, and the Final Site Plan (SDP200800090) has been approved, you may
contact the Department of Community Development to arrange a pre - construction meeting with a County
Erosion & Sediment Control Inspector.
\\ Cob- dts01 \cityviewlnk\Docs\2008 \SDP \SDP200800090 Rivanna Plaza\M_fsp, esc, swm_ADP_Rivanna Plaza.doc