HomeMy WebLinkAboutWPO201000057 Review Comments Stormwater Management Plan 2010-10-27� 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: Avinity [SDP201000072, WP0201000057]
Plan preparer: Scott Collins [scott @collins - engineering.com]
Owner or rep.: Avon Properties, LLC
Plan received date: 9 September 2010
Date of comments: 27 October 2010
Reviewer: John P. Diez — Current Development - Engineering Technician
A. Final site plan (SDP201000072)
1. Please provide date and source of topographic information. All topography should be at least
visually field verified by the designer within the last year. [18- 32.6.6]
2. VDOT approval must be obtained for any plan affecting public right -of -way.
3. Labels for the drainage structures do not match with details and profiles. Please revise.
4. It appears that the dimensions for the dumpster pad on the plans do not match the details. please
revise.
5. Stationing must be provided at a minimum of 50' on all proposed streets, matching the street
profile.
6. Please provide typical retaining wall details referenced from the plan. A typical manufacturers
drawing for segmental block walls, or VDOT reference, is acceptable, with any applicable safety
railings or guardrail shown.
7. All utility crossings must be shown of the drainage profiles. Please revise.
8. Pipe slopes must be 0.5% minimum to 16% maximum. Per VDOT standards for anchors over
16 %.
9. There must be no excessive outlet velocities exceeding 15 fps.
10. All spreads for curb inlet in sump conditions must be less than 10'.
11. The minimum K -Value for the road profile on Avinity Court (Sheet R -1) is not being met.
12. Please provide street name signs to all proposed streets.
13. It appears that the proposed ditch does not match the details on sheet DP -3. In addition, the
grading for the ditches on both sides of the site does not match with the approved preliminary site
plan. Positive drainage from buildings must be provided for the rear portion of the lots.
14. Please provide a street name sign on the intersection of Avinity Place and Avinity Loop.
15. Please provide a street section of Avinity Loop showing parallel parking and sidewalks.
16. Before the site plan can be approved, all offsite easements needed for the construction of the Avon
Street Extended improvements must be recorded. It appears these easements include, but may not
be limited to: drainage, gas, and grading /construction. Additional ROW may also be needed to
meet clearance requirements if determined by VDOT.
17. Approval from Charlottesville Gas must be received before the site plan can be approved. Please
forward their approval to county engineering once it is received.
B. Stormwater Management Plan (WP0201000057).
18. Please provide a completed copy of the standard stormwater maintenance agreement and fee for
recordation for any stormwater management facilities.
19. Please provide a trash rack on all orifices and the culvert to the stormfilter vault_
Engineering Review Comments
Page 2 of 2
20. Please provide plans and details for the proposed Retention Basin Type III. Please be advised that
Type III basins require an aquatic bench, sediment forebays (with vegetation), and the water
quality volume within 6ft of the pond surface. Please refer to the Virginia Stormwater
Management Handbook.
21. There seems to be some issues in the stormwater routing calculations:
A.) The plan and details for the Contech system shows five (5) 90' long barrels and
two (2) 62' long barrels. However the routing seems to use only 4 of the 5 -90'
long barrels. Please revise.
B.) The length of the weir (emergency spillway) is incorrect. At the 521.00 elevation,
the weir length must be 8.39', not 10'. In addition the weir discharge must be
changed to "in riser ".
C.) The invert elevation for the barrel (Outlet Structure #2) seems to be incorrect.
Please revise.
D.) The 10" orifice for the weir (emergency spillway) seems to be missing in the
routing calculations.
E.) Please provide calculations from Contech showing diameter or depth being used
in the routing calculations. In other words, what is the average discharge capacity
for each stormfilter cartridge? The use of an orifice of 0.5" for each cartridge
seems unusual.
F.) Please provide a signed manufacturer's approval letter from Contech for the
facilities.
G.) If the area used for the time of concentration from post - development drainage area
#lA is excluded will a greater discharge be the result? If yes, please exclude this
area from the analysis.
Once these comments have been addressed, please submit two (2) copies of the revised plans, calculations,
and narratives to Current Development Engineering.
Current Development Engineering is available from 2:30pm — 4:00pm on Thursdays to discuss these
review comments. Please contact John Diez at 434 - 296 -5832 or jdiez @albemarle.org to schedule an
appointment.
If you have any questions, you can reach me, John Diez, at (434) 296 -5832 ext. 3025, or my email:
jdiez@albemarle.org.
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