HomeMy WebLinkAboutFDP201500008 Review Comments Floodplain Development Permit 2016-02-05COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902-4596
Phone (434) 296-5832 Fax (434) 972-4126
Project: Doyles River Crossing, 4877 Browns Gap Turnpike (Private Residence)
Plan preparer: William S. Moore, P.E./Scott Kesecker, EIT / Balzer & Assoc. Inc.
1561 Commerce Road, Suite 401, Verona, VA 24482; skesecker(abbalzer.cc
Owner or rep.: Kathleen Patricia Maybury and Joseph Bryant Calhoun III
1318 N. Wakefield Street, Arlington, VA 22207
Plan received date: 10 Dec 2015
Date of comments: 5 Feb 2016
Reviewer: John Anderson
Floodplain Development Permit (FDP201500008)
Note: commend Applicant for level of structural and hydrologic detail.
Comments
1. Structural:
1. Recommend guardrail/curb to protect against 5' vertical drop; design lacks safety element. As
there is no clear ordinance driving recommendation, ref. NSPE Code of Ethics/fundamental canon:
hold paramount the safety, health, and welfare of the public. Recommend revise crossing width to
provide space for 12' clear path plus barrier/s against accidental off -crossing vehicle movement.
2. Label width of embedded downstream edge of concrete (longitudinal /stream in-line dimension).
Clarify whether upstream edge of concrete is to receive embedded downturn.
3. S 1 –Typical cross section and edge profile detail indicate Class 1 backfill compacted to 95%
standard proctor, but do not indicate staged construction. Recommend provide plan/profile details
with sequence notes that consider steel reinforcement (rebar) required to tie separate concrete pours.
Multiple pours appear needed to embed edges, the place compacted backfill, then pour deck, for
one half, then the other. Reinforcing steel should knit each section (pour) to subsequent sections.
4. Recommend monolith (strip) footers beneath upstream/downstream embedded downturns to help
limit scour, to provide additional stability against—and to withstand periodic overtopping events.
2. Floodplain:
1. Please confirm private driveway access, not potential private street subdivision access (17.3 Ac. site).
2. Show existing crossing in approximate detail –provide Notes/plan view details that clarify existing
conditions and demolition. Estimate FILL removed. Compare with calculated FILL proposed (cy).
3. Provide current BFE to nearest 0.1'. Provide proposed BFE to nearest 0.1'.
[18-30.3.11/Table, Permitted Uses]
Stream Crossings and Grading Activities*
Stream crossings for driveways serving single-family dwellings and pedestrian
trails, including, but not limited to, pedestrian and multi -use paths that are within
county -owned or operated parks and greenways, and any footbridges necessary to
cross tributary streams, watercourses and swales, that: (i) meet the applicable
requirements of sections 17-406 and 17-604; (ii) demonstrate, in a floodplain
BR
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impact plan, to the floodplain administrator's satisfaction, that construction of the
crossing will have no impact on the elevations or limits of the floodplain; and (iii)
will serve one dwelling unit that could not be accessed by any other means.
4. Provide copies of VMRC, USACE, DEQ permits, as applicable, required to work in live stream as
pre -requisite to receiving Alb. County Floodplain Development Permit [ref. 44 CFR § 60.3(a)(2)].
Engineering comments
Page 2 of 3
Prepare and complete FEMA Elevation Certificate for proposed structure (Attached).
[http://www.fema.gov/media-library-data/20130726-1437-20490-3457/f 053_ elevationcertificate_jan13.pdf ]
Provide PE -seal `No Rise' Certification. Example, image below.
[from: b_q://www.fema.gov/media-library-data/20130726-1535-20490-4864/unit5.pdf p. 231
"NO -RISE" CERTIFICATION
This is to certify that I am a duly qualified registered professional engineer li-
censed to practice in the State of
It is further to certify that the attached technical data supports the fad that
proposed (Name of Development) will not impact the 100 -year flood
elevations, floodway elevations, or floodway widths on
(Name of Stream) at published sections in the Flood Insurance Study for
(Name of Community) dated (Study Date)
and will not impact the 100 -year flood elevations, floodway elevations, or flood -
way widths at unpublished cross-sections in the vicinity of the proposed devel-
opment.
Attached are the following documents that support my findings:
Date:
Signature:
Title: {SEAL}
Stream Crossing:
1. Provide plan schematic of ESC measures required to: remove existing crossing (with cofferdams);
construct proposed crossing (with cofferdams); store materials above 10 -yr stream stage elevation.
2. Mitigation plantings are required in areas available once existing crossing is removed; 2:1 ratio is
unlikely. Provide Mitigation Plan —plant QTY/schedule (buffer, orange, image below). [17-604.C.5.]
3. Recommend labels make explicit that at least one culvert is to be countersunk 6" below stream bed.
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Engineering comments
Page 3 of 3
g. Establish—i of buffer vegetation, For stream crossings where any portion of the pre -
construction stream buf%r is nil fully vegetated as determined by the administrator, and
for any portion of a vegetated sueara buffer that is disturbed during the installauen ofthe
Am= crossing, buH'er vegetation shall be established and maintained within the stream
butter but outside of the stream crossing at a ratio of two (2) square feel of stream
buffer restored for every one )1) square foot of stream buffer that was either not fully
vegetated or is disturbed during the installation of the stream crossing. Buffer vegetation
shall be established and maintained at the 2:1 ratio to the extent that the stream buffer is
filly vegetated outside of the stream crossing, provided that the owner shall not be
required to establish vegetation outside of the stream buffer in order to satisfy the 2:1
ratio_ The administrator may require [hat the owner enter into an agreement providing for
the ongoing maintenancr of the plantings in the stream buffer, and may require a bond
with surety or other acceptable instrument as provided in section 17414. Stream buffer
plammgs shall be consistent with guidance supplied by the adrmmi tratir
Please feel free to call to discuss, or schedule a plan review meeting: tel -434.296.5832 —x3069. Thank you
File: FDP201500008_Doyles River Crossing_020516