HomeMy WebLinkAboutWPO200800063 Review Comments Stormwater Management Plan 2008-08-12ALg�,��
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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- 2008 - 00063, Oliva and Son Major WPO
Plan preparer: Mr. Tim Miller, PE (fax 434.979.1681)
Owner or rep.: Richard A Oliva and Sons (fax unknown)
Date received: 28 May 2008
(Rev. 1) 6 August 2008
Date of Comment: 10 June 2008
(Rev. 1) 12 August 2008
Engineer: Phil Custer
The WPO plan for the Olivia and Sons site has been reviewed. The following comments are provided.
A. WPO- 2008 -00063
The proposed disturbances are slightly under the 10,000sf threshold for the requirement of an
Erosion and Sediment control plan (I estimate the disturbances to be just under 9,500sf). If
disturbances are increased in later revisions to the plan or during construction, an Erosion and
Sediment control plan will be required. If the over 10,000sf violation occurs during construction
operations, a stop work order will be given until an ESC plan is approved. The owner should be
made aware of this risk now.
(Rev. 1) Comment has been noted by the applicant.
2. A requirement for adequate channel analyses is also provided for in the state stormwater
management law. Section 4VAC50 -60 -70 references the adequate channel requirement. An
analysis of the downstream pipe system will be required for this project.
(Rev. 1) Comment has been withdrawn.
3. The BMP spreadsheet indicates that a biofilter with a 65% removal rate is required but no sizing
calculations were provided. Please provide these calculations indicating that the bed area is 4% of
the impervious area draining to the facility.
(Rev. 1) Comment has been addressed.
4. All water quality facilities require sediment forebays for inflow points. The sediment forebays
should be sized for a 0.1" to 0.25" of the impervious area draining to them.
(Rev. 1) Comment has been addressed.
5. The county now requires that a mix meeting the "state approved standards" be placed in the
biofilter and not "Luck Bio -filter Mix." Please adjust the detail. [DM]
(Rev. 1) Comment has been addressed.
6. The soil media layer must be 2.5ft. [DM]
(Rev. 1) Comment has been addressed.
7. The gravel layer must be 1.5ft. [DM]
(Rev. 1) Comment has been addressed.
8. Please remove any reference to a sediment trap on the biofilter detail.
(Rev. 1) Comment has been addressed.
9. The perforated underdrain must be 6" in diameter. [DM]
(Rev. 1) Comment has been addressed.
10. The minimum diameter for pipes in stormwater facilities is 15 ".
(Rev. 1) Comment has been addressed.
11. Please provide an access path to the facility. [DM]
(Rev. 1) Please widen the access path to ]Oft. [DM]
12. Please label the contours in the biofilter on the drawing.
(Rev. 1) Comment has been addressed.
13. Please show the underground electric line on the profile of the biofilter outlet pipe.
(Rev. 1) Comment has been addressed.
14. The planting ratio (shrubs to trees) should be between 2 to 1 and 3 to 1. Therefore, 2 trees (two
different species) and 6 shrubs (3 different species) will be required in this biofilter, though it
appears 8 plantings are more than enough for a biofilter of this size.
(Rev. 1) Comment has been addressed.
15. Three to one slopes are required in the biofilter. [DM]
(Rev. 1) Comment has been addressed.
16. Please provide lft of freeboard during the 100 -year storm. [DM]
(Rev. 1) Comment has been withdrawn.
17. Please provide the county notes on the plan for "General Construction for SWM plans."
(Rev. 1) Comment has been addressed.
18. (Rev. 1) Please submit a SWM Facility Maintenance Agreement and fee. This document and
submittal instructions are available on the County website. If you have any questions regarding
the submittal of the document, please contact Pam Shifflett (296 -5832 x3246) after consulting
the resources online.
File: E1 swm PBC 08 -00063 Oliva and Sons