HomeMy WebLinkAboutWPO201500025 Review Comments Stormwater Management Plan 2015-08-19 •
k, ,=- COLLINS .='°m i»"°b� Pt: x 1 200 GARRETT ST,SUITE K CHARLOTTESVILLE VA 22902
434.293.3719 PH 434.293.2813 FX
• www.collins-engineering.com
August 19,2015
John Anderson
Department of Community Development
401 McIntire Road
Charlottesville,VA 22902
RE: WPO 201500025—CMA Properties
Thank you for your comments dated August 13,2015 on the above-referenced project. The updated plans reflect
changes to address your comments as described below:
A. Stormwater Pollution Prevention Plan(SWPPP)
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2. Future Development now replaces Phase II notation.
Pollution Prevention Plan(PPP)
1. The responsible pollution prevention party is now named.
2. A concrete wash-out is now added to the pollution prevention plan.
B. Stormwater Management Plan(SWMP)
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6. Responses to follow-up below
i. The facility grading charts have been revised for clarity,the total facility area is now provided on the
right and areas total correctly. The filter cell total volume has been recalculated from 485-491 at 25%
porosity and provides in excess of the required treatment volume.
ii. The underdrains have been revised to 10'o.c.and extended to the edges of the basin.
iii. The daylighting phrase has been removed from sheet 7.
iv. The cleanout detail has been revised with a note specifying a minimum 6"-9"cap placement above
the mulch layer.
v. A note specifying the depth of burial of the 24"thick concrete foundation has been provided on the
sheet.
vi. The basin floor elevation is now labeled in the profile.
vii. The seeding square footage quantity has been provided,1 lb.of each type shall be purchased.
viii. The forebay,bioretention cell,and detention cell dimensions are now labeled.
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14. The emergency spillway has been shifted to allow it to be installed at existing grade and in cut. The basin and
spillway will be constructed with equipment located on this property only. The proposed spillway will activate
only in the 100-year storm,and will sheet flow down to the existing storm sewer outfall on the adjacent
property,and into the existing defined channel.
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17. The riprap note has been revised on sheets 4 and 7.
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21. Additional existing contour labels have been added to the bioretention basin detail on sheet 7.
22. The barrel outfall has been shifted and a cleanout included in the embankment top of dam to provide adequate
spacing between trench and tree save area.
23. A manhole cleanout has been added to the barrel outfall in the embankment top of dam.
24. A yard inlet has been added adjacent to inlet 14,and a hatch showing the swale leading runoff to this inlet is
now hatched,see bioretention basin detail sheet 7.
25. The curb has not been provided on the western lot boundary as this is an interim phase and the parking lot will
be extended in the future and will at that time have CG-2 installed.
C. Erosion and Sediment Control Plan(ESCP)
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A.ii.The 510 contour swale shall be installed as a permanent measure to convey the Berkmar roadway drainage to
the final bioretention basin forebay via the proposed yard inlet. During ESC and before the storm sewer is
installed,a temporary diversion will convey flow to the basin.
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B.ii.No temporary easement will be granted from the existing adjacent landowner. The swales and grading have
been designed as to be constructed from the subject property side only.
C.i.
C.ii.EC-3 matting note added.
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4. All pavement will be removed,the pavement to be preserved is for staging only,and will be removed after the
staging area is no longer needed.
Should you have any questions,please feel free to contact me at 434-566-3011 or at graham@collins-engineering.com
Sincerely, •
Graham Murray,PE
Collins Engineering