HomeMy WebLinkAboutWPO201700073 Correspondence 2018-02-22 (2)Y . + Dewberry Engineers Inc. 804.290.7957
Dewberry �.� y 4805 Lake Brook Drive, Suite 060 www.dewberry.com
fax
Glen Allen, VA 23060 www.dewberry.com
February 12, 2018
David James
County of Albemarle
Planning Services
401 McIntire Road
Charlottesville, VA 22902
RE: Boar's Head Inn Lobby Renovation and Parking Relocation
(SDP20170oo65)
Dear David James,
In response to your engineering comments via comment letter dated December 7, 2017
we offer the following responses:
A. Stormwater Pollution Prevention Plan
The SWPPP content requirements can be found in County Code section 17-405. A
SWPPP must contain (1) a PPP, (2) an ESCP, (3) a SWMP, and (4) any TMDL
measures necessary.
1. Insert a copy of General Permit coverage when obtained.
Dewberry Response: General Permit will be added to the SWPPP when
obtained.
B. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17-404.
(PPP requirements have been adequately addressed)
C. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or
disapprove a SWMP. This plan is disapproved, and the reasons are provided in
the comments below. The stormwater management plan content requirements
can be found in County Code section 17 403.
1. Cover — Please remove the SDP number in title and add the WPO number.
Dewberry Response: The WPO number has been added on Sheet T1.o1 to
replace the SDP number.
2. Show SWM easements over all permeable pavement, and underground
detention system.
Dewberry Response: SWM easements have been added over all permeable
pavement and underground detention and have been shown on Sheet C3.01.
3. Please label proposed drainage structures & corresponding design related
details.
Dewberry Response: Structures have been labeled on the Sheets C3.03 and
C3.04 as well as on the profiles on C4.o1 and C4.02. Details have been added to
C5.03 and C5.o6.
David James
Boar's Head Inn Lobby Renovation and Parking Relocation
SDP20170oo65
February 12, 2018
Page 2 of 5
4. Provide drainage computations with DA map.
Dewberry Response: Drainage Areas and computations can be seen on Sheet
C6.03. Additional drainage area information can be found on Sheet C6.oi.
5. Provide proposed stormwater drainage profiles.
Dewberry Response: Stormwater drainage profiles have been added as Sheets
C4.oi and C4.02.
6. Permeable Pavement (VADEQ SW Design Spec. 7)
a. Underdrain — Show perforated pipe installed for the full length of the
permeable pavement cell, and non perforated pipe, as needed, is used to
connect with the storm drain system.
Dewberry Response: Perforated underdrains have been added through
the permeable pavement areas, and connecting to proposed stormwater
structures.
b. Field -verified infiltration tests required, 1-2 per facility.
Dewberry Response: The contractor will be required to complete the 1-
2 field verified infiltration tests, and will report to the Engineer is there are
any issues.
c. Confirm the depth to seasonal high groundwater table and bedrock
(minimum 2 ft. below the design bottom of the facility).
Dewberry Response: Geotechnical report will be completed, and the
County will be notified if this is an issue.
d. Show underdrain at 0.5% min slope.
Dewberry Response: A note has been added to the underdrain detail on
Sheet C5.04.
e. Use an impermeable liner along the sides closest to the `Boars Head Inn'
building.
Dewberry Response: A note has been added to the underdrain detail on
Sheet C5.04.
f. Located loo'from any water supply well and 35'from any septic system.
Dewberry Response: A note has been added to the underdrain detail on
Sheet C5.04.
g. The owner should be informed of the routine long and short term
maintenance actions.
Dewberry Response: The owner is aware of the maintenance required.
h. Plan landscaping to limit the amount of soil, mulch, grass clippings,
leaves, nuts and fruit that may inadvertently clog the paving surface.
Dewberry Response: Landscaping will limit the amount of the
materials that could potentially clog the pavers.
i. Include the construction sequence and installation notes from section 8.2
and 8.3 Construction inspection notes in the plan.
Dewberry Response: The construction sequence and installation notes
from section 8.2 and 8.3 have been added to Sheet C6.03.
7. Please identify each practice and show each CDA on a separate sheet. Looks like
there may be 8 individual cells.
Page 2 of 5
`�pe. Dewberry�.�
David James
Boar's Head Inn Lobby Renovation and Parking Relocation
SDP20170oo65
February 12, 2018
Page 3 of 5
Dewberry Response: Paver area and contributing drainage areas have been
shown on Sheet C6.05.
8. Show/provide Rv calcs.
Dewberry Response: Rv calculations for pre and post conditions have been
broken down and shown on Sheet C6.05.
9. Provide storm pipe & inlet design calcs.
Dewberry Response: Storm Schedule has been added to Sheet C6.05.
lo. Please show pipe flow direction arrows.
Dewberry Response: Pipe flow direction arrows have been added to Sheet
C3.o3.
11. Sheet C3.02 — Storm pipe shown connecting two inlets, where does stormwater
go from there?
Dewberry Response: The existing inlet continues west, towards the existing
service road. An approximate location of existing pipe has been shown on Sheet
C3.o4.
12. Sheet C3.o3
a. Add a manhole over 12"pipe outfall at connection with stormwater vault.
Dewberry Response: The configuration of the underground stormwater
system has changed. No manhole is needed.
b. Consider relocating DI-3B (TOP=559.92') a bit further downstream.
Dewberry Response: The location of this structure, now a DI-3C has
been shifted.
13. Sheet C5.03 — UD Vault details
a. Add Upstream or Downstream for the vault detail titles.
Dewberry Response: The configuration of the underground stormwater
system has changed. There is only one vault detail.
b. Show the pavement/CG cover/Finished grade
Dewberry Response: Finished grade has been labeled on the vault
detail as well as the culvert box detail.
c. Show that maintenance access will be provided to downstream/outlet
side of weir.
Dewberry Response: Access manholes have been shown in plan on
Sheet C3.03, and in the details on Sheet C5.03.
d. Section B is shown incorrectly (opposite direction of arrows)
downstream.
Dewberry Response: The detail has been revised.
e. The 9"H shown in the 9x36 orifice doesn't match the model/calcs of 6"H
on sheet C6.o6.
Dewberry Response: The orifices have changed and have been labeled
on the detail on Sheet C5.03, consistently with the calculations shown on
Sheet C6.o6.
f. Is the box culvert 2" thick?
Dewberry Response: The slab is a minimum 8" thick as stated in the
detail on Sheet C5.03.
g. Show the weir height and clearance dimensions.
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David James
Boar's Head Inn Lobby Renovation and Parking Relocation
SDP20170oo65
February 12, 2018
Page 4 of 5
Dewberry Response: The weir height and dimensions have been shown
on the detail on Sheet C5.03.
14. Sheet C6.o1 — Show in SWM narrative computations that your SWM design
meets Part II(B) requirements. Show that Energy Balance, or channel/flood
protection to the limits of analysis is met.
Dewberry Response: A statement stating that we've met Channel protection
and Flood protection has been added to Sheet C6.o1, including calculations.
15. Sheet C6.o6
a. Confirm if 12" outfall pipe of UD vault system is the primary outfall in the
post development routing calcs. If not, please include.
Dewberry Response: The outfall of the underground detention system
is the primary outfall in the routing calculations.
b. Confirm if o.97ac is t00% impervious.
Dewberry Response: The curve numbers used in AutoCAD were pulled
from the spreadsheet shown on Sheet C6.oi or from the VRRM
Spreadsheet summary shown on Sheet C6.03.
16. Sheet L3 — Please identify PO, what type of tree?
Dewberry Response: Landscaping sheets have been revised for clarity. See
Sheet L3 for designation.
D. Erosion and Sediment Control Plan (ESCP)
Virginia Code §62.1-44.15:55 requires the VESCP authority to approve or
disapprove an ESCP. This plan is disapproved, and the reasons are provided in
the comments below. The erosion control plan content requirements can be
found in County Code section 17-402.
1. Please show callouts for proposed structures & E&S controls to a detail sheet.
Use leaders/extend arrows/shading for clarity where needed.
Dewberry Response: Proposed structures and E&S controls are shown on
Sheets C2.01, C2.02, C3.05, and C3.o6. Details can be found on Sheet C5.01.
2. There are managed slopes near the parking lot. Please show the managed
slopes on the existing site conditions sheet(s).
Dewberry Response: The managed slopes on the existing site have been
hatched on Sheet C1.02.
3. Provide low maintenance ground cover where grades are steeper than 3:1, see
sheet C3.04.
Dewberry Response: Low maintenance ground cover where grades are steeper
than 3:1 will be provided as needed.
4. Sheet C2.o1/C3.o5
a. Provide `sediment control logs' or similar at the entranceways of the
existing parking lots.
Dewberry Response: Additional sediment control devices and notes
have been added to ensure sediment will not travel offsite. See notes and
details on Sheets C2.01, C2.02, C2.03, C2.04, C3.05, C3.o6, C5.01.
b. Fix leader should point to the concrete washout.
Dewberry Response: This leader has been revised.
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`� -"F Dewberry
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David James
Boar's Head Inn Lobby Renovation and Parking Relocation
SDP20170oo65
February 12, 2018
Page 5 of 5
5. Provide concrete washout details. Is hay bale acceptable?
Dewberry Response: Concrete washout detail has been added to Sheet C5.05.
6. Sheet C3.o6 — Provide `sediment control log' along parking lot entranceway.
Dewberry Response: Additional sediment control devices and notes have been
added to ensure sediment will not travel offsite. See notes and details on Sheets
C2.01, C2.02, C2.03, C2.04, C3.05, C3.o6, C5.01.
7. Sheet C5.o1 — Add CE symbol to `Paved wash rack' detail.
Dewberry Response: This detail has been removed.
Thank you for your attention in this matter. Please contact me with any questions or
concerns at (804) 205-3321 or email Reeler (&dewberry. com
Sincerely,
Devin Keeler, P.E.
Dewberry
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