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CIVIL ENGINEERING | ENVIRONMENTAL | SURVEYING | GIS | LANDSCAPE ARCHITECTURE | CONSTRUCTION SERVICES
608 Preston Avenue
Suite 200
Charlottesville, VA 22903
P 434.295.5624
F 434.295.8317
www.timmons.com
December 20, 2018
County of Albemarle
John Anderson, PE
Engineering Division
401 McIntire Rd
Charlottesville, VA 22903
RE: Lewis & Clark Drive Extension – Road Plan Review – SUB-2018-00171 – Rev.1 - Comment
Response Letter
Dear Mr. Anderson:
We have reviewed all of your comments from November 9, 2018 and made the necessary
revisions. Please find our responses to the comments below in bold lettering.
1. Avoid wetlands to extent practicable; provide exhibit(s) showing roadway CL shift to the
west to avoid wetlands to extent practicable.
Exhibit demonstrating how current alignment decreases impacts from original road alignment
was emailed to John Anderson on 12/18/2018.
2. Stormwater Management Note, C0.0 references “Stormwater Management/BMP
Analysis and Floodplain Study for the UVA Research Park at Northfork” by Dewberry &
Davis, October 1997.” The note continues: ‘The Research Park has been master planned
for Stormwater Management for the future build-out of the research park. The Majority
of this road project drains to the large wet pond to the east that was designed and
constructed to handle quantity and quality for the future build-out of the research park
including this road connection.’ End note.
Also, same link: “UVA Research Park, Town Center III and IV, Engineering Calculations,”
prepared for UVA Real Estate Foundation by Frank D. Cox, Jr., PE/Cox Company, 220 E.
High St., Charlottesville – Nov. 30, 2006, Rev. March 8, 2007. This document appears
highly-relevant and useful to VSMP/WPO Plan Submittal. Review and include salient
information from this document. See Exhibit 1, beginning p.18 of .PDF. Also: pre-
development drainage map, p.7; a road design not identical with design proposed with
WPO201800073, p.8-9; etc.)
a. Title sheet notation does not of itself sufficiently address plan requirements if
compared with VA Administrative Code stormwater quality or quantity
regulations. It is unclear if Applicant is requesting Engineering accept existence
of a study as sufficient basis for issuing a VSMP VPDES permit under 9VAC25-
870-48, without additional detail or context, including: narrative, data, routings,
pond plan / profile, As-build for Ex. Large wet pond, drainage maps, calculations,
etc. Engineering recommends Timmons take a conventional approach and piece
together information; that is, provide rationale that guides plan review, including
whether 9VAC25-870-48 is basis of VSMP/WPO Plan Application
(Grandfathering). Please provide reference to a ZMA, SP, SDP, or WPO approved
prior to July 1, 2012 that explicitly includes BMPs designed to meet then-current
stormwater management requirements and included with the Dewberry 1997
study. The reference study is twenty-one years old. There are few immediately
recognizable approved ZMAs, SDPs, SPs, or WPOs in Albemarle County’s online
document system (CV) that align with the 1997 study (WPO2006-00087 does).
Timmons must provide information sufficient for Engineering to approve
WPO201800073 without pulling past plans, many of which are listed in CV as not
approved. 9VAC25-870-48, -93/94 (Definitions/Applicability), -95 (General), -96
(Water Quality), -97 (Stream Channel Erosion), and -98 (Flooding) likely govern
proposed roadway construction. Engineering recommends query CV (or visit CDD
to request/consider and review) the following possibly relevant Applications
(listed by type, then chronologically):
i. ZMA2005-00002
ii. SP2008-00062
iii. SDP1997-00046
iv. SDP1998-00043
v. SDP2000-00025
vi. SDP2000-00077
vii. SDP2000-00098
viii. SDP2001-00005
ix. SDP2001-00011
x. SDP2001-00047
xi. SDP2002-00064
xii. SDP2002-00072
xiii. SDP2002-00110
xiv. WPO200600087 (Approved plan not shown in CV; documents
only.)
Through coordination with county records the approved plans and as-builts have been located
and referenced on the plan.
3. Remove road plan sheets from VSMP/WPO Plan, including: C1.1 – C1.3, C4.4 – C4.9;
C6.0, C6.1, C7.0, C8.0 – C8.3: These sheets present road plan detail/s.
The above sheets have been removed from the VSMP/WPO Plan.
4. SWPPP
a. Sign Sec. 1, VPDES Certification (Print, sign, title, date).
Acknowledged. Signature will be added after plan approval to finalize SWPPP.
b. Lat./Lon. Provided appear to be a location in Louisa County. Please revise
Lat./Lon.
The Latitude and Longitude have been checked and represent the project site.
c. Sec. 5: Provide SWM Plan.
11x17 of the SWM Plan have been added to the SWPPP.
d. Sec. 9, Signed Certification: please sign.
Acknowledged. Signature will be added after plan approval to finalize SWPPP.
e. Revise inspection log to provide space for description of inspection observation –
see image, below:
Erosion and Sediment Control Facilities Inspected:
(Inspection shall be conducted according to Part IIF2 of the Permit. However, if
the discharges of stormwater from construction activities are to surface waters
identified as impaired, inspections shall be conducted according to Part IB4d.).
The inspection log has been updated accordingly.
5. Copy Construction Record Drawing (As-built) Policy to plans:
The record drawing notes have been added to plan sheet C1.0.
C3.0:
6. Stormwater Runoff Considerations: Expand to provide descriptive narrative connection
to a prior-approved site plan, special use permit, or water protection ordinance permit
that positively confirms proposed development meets state stormwater quality and
quantity requirements.
Narrative has been updated.
7. Include note that requires Owner to obtain all required state or federal permits, include
VDEQ Individual Permit, VMRC General Permit, or US ACE Nationwide permit (wetland
impacts), etc.
A note has been added to the plan sheet. See “Permitting” section.
8. List special conditions of US ACE permit on the plans. Identify, number, and quantify
area impact to wetlands (SF). Identify wetland type/s using text, labels/notes, graphic
symbols.
Permit will be filed with Army Corp of Engineers. A copy of the permit will be included once
approved.
9. Include ACDSM Paved (construction entrance) Wash Rack detail. Measure required. See
ACDSM, p.9.
Detail has been added to plan sheet C3.2
10. Define/specify slope stabilization seed mix (Ref. legend, C3.2).
Slope stabilization seed mix has been added to sheet C3.2
11. C3.0: It appears 2nd C3.0 (details) should be labeled Sheet C3.1.
Acknowledged
12. C3.1 (relabeled): Include stream diversion detail; for example, VESCH plate 3.25-1, or
variation showing sandbag dam/pump-around diversion.
Stream Diversion detail has been added to plan sheet C3.2.
C2.0:
13. Provide at least one hundred (100) Ex. Contour labels. No legible contour labels appear
to be shown. (It is difficult verging on impossible to interpret existing conditions).
Contour labels have been added and made legible.
14. Label development parcel TMP. Label each adjoining parcel with TMP#.
TMP’s have been added to plan sheet C2.0
15. Provide Mitigation Plan for stream crossings (2:1 mitigation required). Label WPO buffer
areas, if multiple areas. Provide landscape schedule for each WPO buffer area.
Mitigation plan will be provided with permit to Army Corp of Engineers. A copy of the permit
and plan will be provided once approved.
16. Revise critical slopes labels; replace with managed or preserved steep slopes labels.
The slope labels have been revised
17. C3.2 – C3.5: Increase Ex. Contour labels so legible.
Existing contour labels have been adjusted to make them legible.
C3.2:
18. Label ST1 floor dimensions in plan view.
Dimensions have been added to ST1 in plan view.
19. ST1 design treats Max. limit, 3.0 Ac. Show 3.0 Ac. Drainage area boundaries for this
sediment trap.
Drainage area boundaries have been shown as dashed line or have been noted to run along
tops of DD or CWD.
20. ST1: Avoid wetlands. Relocate ST1 since this sediment trap discharges to downslope
wetlands, by design. This means, any event that exceeds capacity of ST1 will discharge
sediment to wetlands, by design, which may cause permanent or irrevocable and not
incidental impact. Do not propose sediment trapping measures upslope of or
immediately adjacent to wetlands.
Sediment trap location has been discussed with John Anderson. The trap is located at the low
point to catch and treat the maximum amount sediment laden runoff from constitution.
However, it has been kept within the final disturbance limits of the road to avoid addition
impact to the wetland’s downslope. There is approximately 100’ of wetlands within the
permanent disturbance limits below the trap which will serve as a buffer to the downstream
wetlands should a storm event above the traps design volume occur. Wire supported silt
fence will be provided downslope of trap during installation and removal.
21. Relocate roadway if necessary to avoid and minimize wetland impacts. Alternately,
provide copy of USACE Permit authorizing proposed wetland impacts.
Road alignment was designed to minimize wetland and stream impacts. Exhibit comparing
current design to original design has been provided to John Anderson in an email 12/?/2018.
22. Label dimensions 39 cy Culv-3 inlet protection to aid review, construction, and
inspection.
Dimensions have been added to the Inlet protection.
23. Label area (acreage) of Limits of Clearing and Grading, x.xx Ac.
The Limits of disturbance has been added to the plan sheets.
24. Calculate velocity (Q2) for channel at bottom of future fill slope, upslope of Culv-3.
Provide soil stabilization, permanent riprap, or concrete conveyance channel as required
for this channel.
Velocity was calculated and shown on sheet C7.0 in ditch section A-A.
25. Show, estimate, label area of wetland impacts (SF). Identify wetland type: emergent,
riverine, palustrine.
A permit with this information will be filed with the Army Corp. of engineers. Once permit is
approved, a copy will be forwarded to you.
26. List U.S. Army Corps of Engineers Nationwide permit (USACE NWP-27/other) issued for
this project. List date of permit issuance. VSMP/WPO cannot be approved without copy
of current USACE permit authorizing specific impacts to specific areas identified, shown
and labelled on the VSMP/WPO plan.
Acknowledged. Permit information will be provided and added to the plans once it is
available.
27. Show wetland protective measures: for example, timber matting and fencing equivalent
to tree protection, for wetlands to be preserved and not authorized by USACE permit to
be disturbed or impacted, either temporarily or permanently, by project activity. Plans
identify no wetlands to be preserved, except by virtue of location outside LOD.
Recommend wetland preservation as cornerstone of design. See other comments on
topic of impact avoidance and minimization, especially concerning Applicant need to
acquire and provide copy of relevant federal or state wetland, stream, or aquatic
resource permits.
Wetland protective measures have been added to the plan sheets.
Design Calculations & Narrative, 9/24/18:
28. Culvert 1 Table breaks across 2 pages; reformat so visible as single sheet.
Culvert 1 Table has been updated.
29. Culverts, 1,2,3 design outfall velocity exceeds 10.0 fps. Include VESCH 3rd Edit., plates
3.36-4 and 3.36-5 on plan sheet C3.0 or C3.1. Ensure labels, notes etc. identify locations
requiring VESCH Std. & Spec. 3.36, and identify which type stabilization matting is
required.
Channel sections down stream of culverts have been added to sheet C7.0 showing 2-year
velocities below 10 fps.
30. (RP comment) Max. outfall velocity is 15fps. Ref. Drainage Plan checklist (drainage
computations, p.2). Revise design such that outfall velocity for all culverts is <15fps (Q2).
Culvert designs have been updated to decrease velocity below 15 fps for the 2 year storm.
31. Provide outfall protection calculations. Ref. VESCH Std. & Spec. 3.18 plates 3.18-3
and/or 3.18-4.
Outfall protection plat has been added for culvert #3 and end section 100 and 200. Culvert 1
and 2 are box culverts and have been designed in accordance with VDOT R&B Standards Sheet
113.01.
32. Culvert 3 OP width 2 is insufficient. Width 1=6.0’ is likely adequate (ref. comment #31).
Ref. VESCH.
Width 2 has been updated.
We have included PDF copies of the plans and calculations for your review. If you have any
questions or comments, please feel free to give me a call at 434.295.5624.
Sincerely,
Jonathan Showalter, PE
Project Engineer