HomeMy WebLinkAboutWPO201300004 Review Comments Erosion Control Plan 2013-03-11i"
,. `IRGINZP
COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project: Ivy Creek Methodist Church (WP02013- 00004)
Plan preparer: Terra Engineering and Land Solutions, P.C. [tel 540- 337 -4591]
Owner or rep.: Ivy Creek United Methodist Church
Plan received date: 15 January 2013
Date of comments: 11 March 2013
Reviewer: Michael Koslow
The first erosion and sediment control and stormwater management plan (WPO201300004)
submitted 15 January 2013 has received Engineering Review and does not appear to meet
Albemarle County minimum checklist items for approval. Please adequately address the following
comments for final approval:
A. Title Information
1) Each sheet of final WPO plan set will require a professional engineer's signature and date for
approval (review copies do not need to be signed).
B. Existing Conditions Information
1) Please include the existing conditions sheet with the WPO submittal.
2) Please visually confirm the topographic survey conditions and note as such on the plans.
Topography over one year old must be field verified by designer.
3) Please include a benchmark location and elevation for reference. An existing utility or other
known position will suffice.
4) Please identify existing easement for existing utilities including overhead electric lines and
underground gas main shown on sheet C2.0 by deed book and page number.
C. Erosion and Sediment Control Plan
1) Please address contractor parking and staging areas. If these areas will require additional land
disturbance, please include those additional land disturbance areas with ESC plan.
2) Please include dust control with ESC plan.
3) Please indicate either trees to remain or trees to be saved for each tree within the limits of
construction of clarity.
4) Please retract silt fence and expand diversion dike behind site east to a relatively flat location
(recommend elevation 550). Silt fence should only be placed in flat locations (ideally along a
contour line).
Engineering Review Comments
Page 2 of 3
5) Please provide an adequate channel analysis for runoff from proposed construction. Analysis needs
to be carried further downstream compared with submitted MS -19 computations shown on p. 28 of
SWM Report dated 10/31/2012. Analysis could be proven given:
a) adherence to VESCH MS -19 requirements (see 4VAC50- 30 -40, MS -19 sec. b (1)): The
applicant shall demonstrate that total drainage area to the point of analysis within the channel
is one hundred times greater than the contributing drainage areas of the project in question. A
report or plan depiction with analysis to this point could prove channel adequacy.
b) adherence to VA code 10.1- 603.4(7): essentially, the required condition for an on -site
solution without looking downstream for a 24 hour 1.5, 2, and 10 -year intensity event -
(post - development) Peak flow rate <= Pf *Vf/Vp
Where Pf = peak flow rate in a forested condition
Vf = runoff volume in a forested condition
Vp = runoff volume proposed
D. Stormwater Management Plan
1) Please include a proposed stormwater management easement around proposed bioretention filter
Please note due to proposed filter media, it appears BMP facility is intended to be a bio- filter.
Please remove references to pond and basin from plans and computations.
2) Proposed bio- filter should not include a clay liner as identified on Note 2 above detail 1 -5.0 `Bio-
Filter Combined with Detention Basin" on sheet C7.0.
3) Please include a cross section of the proposed berm (could modify SWM Pond Riser Outlet to
show entire barrel length through berm). Please draw cross section to a scale for reference (e.g.
the 10" orifice appears to be shown smaller than it actually is proposed in the detail).
4) Because the bio- filter was designed without an emergency spillway, please increase the berm
elevation to provide 2' of freeboard above the 100 year storm elevation.
5) On p. 4 of Stormwater Calculations, please specify rainfall event frequency basis for intensities
shown in pre - development and post - development conditions.
6) Please identify dimensions and material for riser base for riser outlet base proposed on sheet C7.0.
7) Please include a forebay for bio- filter proposed on sheet C7.0. Forebay area must be sized for
25% of bio- filter's floor area. This area cannot be considered for treatment (no filter media);
however it can be included for detention.
8) Please label floor area for bio - filter proposed on sheet C7.0.
Engineering Review Comments
Page 3 of 3
Current Development Engineering is available from 2:30 -4 PM on Thursdays to discuss these review
comments. Please contact Michael Koslow at 434 - 296 -5832 ext. 3297 or email mkoslow @albemarle.org
to schedule an appointment.
[17- 204.f] An application for an erosion and sediment control plan that requires modifications, terms, or conditions to be
included in order for it to be approved shall be deemed to be withdrawn if the owner fails to submit a revised plan addressing the
omitted modifications, terms or conditions within six (6) months after the owner is informed of the omitted information as
provided under paragraph (B).