HomeMy WebLinkAboutWPO202100034 Correspondence 2021-12-17I® COLLINS ENGINEERING
December 16, 2021
David James
Department of Community Development
401 McIntire Road
Charlottesville, VA 22902
RE: Victorian Heights (WPO 202100034)
200 GARRETT ST, SUITE K CHARLOTTESVILLE VA 22902
��434.293.3719 PH 434.293.2813 FX
www.coll i ns-engineering.com
Thank you for your comments dated November 4, 2021 on the above referenced project. Below are our responses to
the remaining comments on the road plans.
A. Stormwater Pollution Prevention Plan
1. Please refer to the Registration Statement within the SWPPP booklet submitted (Section #1). Under
Section II.F. of the Registration Statement, the MS4 says Albemarle County.
2. Sections 4 & 5 will be updated with approved plans.
B. Pollution Prevention Plan
1. These locations are shown/identified on the plans or described in section 6.
C. Stormwater Management Plan
1. Addressed.
2. An inlet drainage map is included with this submission.
3. This comment is acknowledged.
4. Addressed
a. A separate analysis of the sheetflow from the downstream area of Subarea C is included as
an exhibit. The narrative on this exhibit explains how the analysis was done and also explains
why the LOA shown on sheet 8 was chosen.
5. Addressed.
6. Sheet 9—
a. Addressed.
b. Addressed.
c. Addressed.
d. Addressed.
7. Acknowledged.
8. Acknowledged.
9. Acknowledged.
10. Addressed.
11. Acknowledged.
12. Nutrient Credit Letter of Availability has been included with the SWPPP in Section 5.
13. New development VRRM spreadsheet has been utilized and included in SWPPP booklet as noted in
comment above. 5.S6 Ibs/yr of phosphorous removal is still required so the previous Nutrient Credit
Letter of Availability is still valid.
14. Acknowledged. Letter of Availability is from Ivy Creek bank.
1S. A 3.5" low flow orifice is proposed with this submission. This is able to be upsized by taking into
account the upper offsite drainage from the existing culvert crossing Woodburn Road. This drainage
is captured in the proposed storm sewer. As it is offsite drainage, channel protection is not required
to be applied to this runoff and increases the allowable release rate of the low -flow orifice. Please see
sheets 8 and 13 for this drainage delineation and the calculations packet for how this upstream area
has been incorporated into the site's channel and flood protection analysis.
16. Invert of Bypass Pipe has been added. Please see Bypass Profile on sheet 9.
17. Overall Grading plan shows public drainage easements over storm sewer conveying runoff from the
Right of Way. Private drainage easements are shown on storm sewer pipes conveying runoff onsite
up to the point where they join storm sewer that is conveying runoff from the R/W. Please see sheet
11.
D. Erosion and Sediment Control Plan
1. Addressed.
2. Sheet 5—
a. Contours are shown correctly for Phase I. Please start at the right of ST5 where 530 ties in to
the existing contour and follow that existing contour to the left. It remains existing to the
property line. The same with 528. Now, to the right of that proposed 528 contour below the
diversion dike you will find where the 526 contour ties into the existing. This proposed 526
contour makes up the downstream portion of ST5's dam. Following this proposed contour to
the left, you will find that it ties into the existing close to where the diversion dike is shown.
b. Addressed.
c. B/M has been added to downstream dam slope. Corrected this on sheets 6 & 7 as well.
d. Addressed.
e. Addressed.
f. Addressed.
g. Baffles have been added to ST1.
3. Sheet 6/7—
a. Addressed.
b. Addressed.
c. Addressed.
d. Addressed.
e. Grading has been revised. Silt fence has been moved in Phase III to the other side of the
proposed sidewalk where there is a 2%cross slope, beyond the proposed slope.
f. Addressed.
g. Addressed.
h. Addressed.
i. Extra temporary pipe and manhole have been added to revise the temporary back angle.
j. Construction Entrance at Berkmar entrance has been added to Phases II&III.
4. Sheet 7 diversion dike has been adjusted.
5. Addressed.
6. Acknowledged.
7. Liner has been specified for drainage divides going to ST1 and ST2 where there are significant bends.
Please see these on sheets 5 & 6. Calculations for linings are shown on Sheet S.
8. Addressed.
9. Addressed.
10. Addressed.
11. Acknowledged.
12. Addressed.
13. Demo items have been added to Sheet 2.
14. This upstream area has been included in Phase I, upsizing ST5 to a sediment basin, labeled SB3. This
upstream drainage area has also been included in the channel and flood protection analyses as
described in an earlier comment response. Outlet protection for outfall barrel of SB1 is shown on
sheet 5.
Should you have any questions, please feel free to contact Scott Collins at scott@collins-engineering.com.
Sincerely,
Scott Collins, PE