HomeMy WebLinkAboutWPO201200067 Review Comments Stormwater Management Plan 2012-09-18ALg�,��
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COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project: WPO- 2012 - 00067, Old Trail Creekside - Amendment
Plan preparer: Mr. Scott Collins, PE; Collins Engineering
Owner or rep.: Old Trail Creekside, LLC
Date received: 8 August 2012
Date of Comment: 18 September 2012
Engineer: Michael Koslow
The I" submittal of SWM plans for Old Trail Creekside - Amendment, received on 8 August
2012, 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. Stormwater Management Plan Review Comments
1. This WPO amendment should be processed as a Mitigation Plan amendment instead of a
Stormwater Management Plan amendment. For resubmittal, please consider this project a
mitigation plan amendment for application and fee purposes.
2. This project's mitigation treatment requirement is discussed in comment #132 from 2/3/2005
review of Old Trail Creekside WPO plans (WP020050005):
...Please keep in mind that these facilities are for purposes of buffer mitigation, addressing the
concentrated discharges. They do not have to meet the volume and area requirements, though it
would be nice if they did.
Please depict a plan for providing an equivalent level of mitigation plantings compared with the
plantings and water quality treatment included with the approved bio- retention facilities from
WP0200500005. One method could be to consider the originally approved buffer disturbance
areas. The county would typically require mitigation plantings at a rate of twice the disturbed
buffer area. However, for this project (WP0200500005), the county instead approved the
installation of two bio - retention areas.
Bio- retention areas which treat 0.5 inches of runoff from the impervious areas provide a 50%
Removal Rate per Virginia Stormwater Management Handbook (VSMH) Table 3.11 -1. The dry
detention basins proposed with this amendment provide a 35% Removal Rate per VSHM Table
3.07 -1. Therefore additional streambank mitigation plantings are required to account for the
difference in mitigation. Effectively, the area of required additional streambank mitigation
plantings is 2 * 15% * the originally approved buffer disturbance area from WP0200500005.
3. After demonstration of how additional planting mitigation requirements is submitted, further
analysis of the proposed extended detention ponds may commence. Preliminary review of the
proposed extended detention basins indicates they will need to be designed in consideration of the
requirements in VSMH Sec. 3.07. Examples of these requirements include providing a sediment
forebay and a demonstration of extended detention with a typical 30 -hour draw down time.
4. A modification to the project's stormwater management maintenance agreement will be required
for modified stormwater management features and additional mitigation planting areas proposed
with this amendment.
5. Additional mitigation planting areas will require an easement.
Once the comments have been addressed, please submit 2 copies of the revised plans, calculations, and
narratives to Community Development Engineering along with the required review fee and transmittal
form.
Community 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).
File: C: \Users\mkoslow\Documents \Current Reviews \WP0201200067 Old Trail Creekside -
Amendment\E1 MAK SWM Old Trail Creekside - Amendment WP0201200067.doc