HomeMy WebLinkAboutWPO201200092 Review Comments Erosion Control Plan 2013-02-20i"
,. `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:
Old Trail Village Block 14 Early Grading (WP02012- 00092)
Plan preparer:
Collins Engineering [tel 434- 293 -3719]
Owner or rep.:
March Mountain Properties I LLC
Plan received date:
4 December 2012
(Rev])
22 January 2013
Date of comments:
9 January 2013
(Rev])
20 February 2013
Reviewer:
Michael Koslow
The second erosion and sediment control plan (WPO201200092) submitted 22 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:
Existing Conditions Information
1) Please visually confirm the topographic survey conditions shown on sheet 2 and note as
such on the plans. Topography over one year old must be field verified by designer.
(Rev]) Comment has been addressed.
2) Please label all existing public and private road street names wherever they are shown on
plan sheets.
(Rev]) Comment has been addressed.
Plan Detail Information
1) Please include Albemarle County General Construction Notes as shown in County Design
Standards Manual located here (see p. 22):
< htip: / /www.albemarle.org/upload /images /forms center /departments /community development/forms /
design standards manual/Albemarle—County—Design—Standards Manual 220ct2Ol2.pdf>
(Rev]) Comment has been addressed.
Erosion and Sediment Control Plan
1) Please depict in plan view the entire 7.15 Acres of Limits of Disturbance.
(Rev]) Comment has been addressed.
2) Please depict in plan view the entire 7.78 Acres of contributing are to Sediment Basin #2.
(Rev]) Comment has been addressed.
3) Please delete all references to proposed water or sewer mains from this early grading plan
including portion of note #2 on sheet 4 which reads "Construction activity within the stream buffer
Engineering Review Comments
Page 2 of 2
shall be limited to the installa4ion ".
(Rev]) Comment has been addressed.
4) Calculations for the required diameter for the dewatering orifice for Sediment Basin #2 indicate it
should be nearest inch increment below 5.17 ". Please decrease the diameter to 5 ".
(Rev]) Comment has been addressed.
5) Please include existing contour elevation labels on sheet 4.
(Rev]) Comment has been addressed.
6) Per VESCH Table 3.14 -D, the prescribed trash rack appears to be undersized and corresponding to
a 27" diameter riser. Please correct trash rack cylinder diameter.
(Rev]) Comment has been addressed.
7) Please provide an adequate channel analysis for runoff from proposed construction. 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 *VfNp
Where Pf = peak flow rate in a forested condition
Vf = runoff volume in a forested condition
Vp = runoff volume proposed
(Rev]) Please revise calculations to show correct riser outlet invert elevation (apparent elevation
used was barrel outlet instead) for routing. Please revise calculations to reflect worst case flow scenario
(bare earth). Please revise calculation to show a proportion of volume relative to the different
watersheds being compared (i.e. the actual runoff volume from a pre forested condition for the site vs.
the actual runoff volume for a post - construction condition for the site including off -site water draining
to propose Sediment Basin #2).
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).