HomeMy WebLinkAboutWPO200800059 Review Comments Erosion Control Plan 2008-11-06� OF AL
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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: Airport Runway 21 Extended Runway Safety Area (WP0200800059)
Plan preparer: James D. Nixon, Jr. P.E. Delta Airport [fax(804)275-8371]
Owner or rep.: Barbara W. Hutchinson C.M. Exe Director [fax (434) 974 -7476]
Plan received date: 5 Novmeber 2008
Date of comments: 6 November 2008
Reviewer: Current Development Engineering
The Erosion and Sediment control plan submitted November 5, 2008 has received Engineering review.
The plans cannot be approved as submitted and will require the following changes /corrections prior to final
approval.
Please revise the riser detail of Sediment Basin "D" on Sheet 28A, the diagram does not appear to
accurately reflect the invert elevations.
2. The c- coefficients utilized in the Phase C sediment basin sizing calculations continue to reflect a
forested/grassed condition. This is inaccurate due to the clearing /grubbing and grading which will
take place during this construction phase. A c- coefficient of 0.45 would more accurately represent
the disturbed area. Revising these c- values may result in adjustments to the design of the basins
and/or their risers.
In Phase D, Sediment Basin "D" does not account for flow from Area "A ". It is recommended
that the embankment and accompanying riser and 24" pipe of Sediment Basin "EO" be removed
and the area be stabilized. Then, the pipe from Sediment Basin "A" should be redirected to this
stabilized channel.
4. This plan does not demonstrate that the requirements of MS -19 are being satisfied. We expect that
a detailed analysis will occur with the resubmittal of the stormwater management plan. However,
measures must be taken to ensure that downsteam properties are protected during construction.
Please verify that the existing channel will not erode during a 2 -year storm and that the channel
and the existing 36" pipes under Crickenberger Lane have the capacity to handle a 10 -year storm
with the airport site under construction (c- coefficients reflecting disturbed area, not forested/grass).
Once these comments have been addressed, please submit 2 copies of the revised plans,
calculations, and narratives to Current Development Engineering.
Current Development Engineering is available from 2:30 -4 PM on Thursdays to discuss these review
comments. Please contact Amy Pflaum at 434 - 296 -5832 ext. 3069 or apflaum @albemarle.org to schedule
an appointment.
File: E3_esc_ADP_Airport Runway 21 Ext Runway Safety Area.doc