HomeMy WebLinkAboutWPO202100034 Correspondence 2021-10-04M COLLINS ENGINEERING
September 22, 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 ns-eng ineeri ng.com
Thank you for your comments dated July 16, 2021 on the above referenced project. Below are our responses to the
remaining comments on the road plans.
A. Stormwater Pollution Prevention Plan
1. MS4 has been added
2. Sections 4 & 5 are added with this submittal.
3. The approved plans will be added to the SWPPP report once they have been signed.
B. Pollution Prevention Plan
1. These locations are shown/identified on the plans or described in section 6.
C. Stormwater Management Plan
1. WPO # has been added under project title on cover sheet.
2. All other WPO Plans we've submitted have never included drainage map for individual structures and
only show specific design elements pertaining to the underground detention system itself. While we
show the drainage system as a whole to show how drainage flows into the underground detention
system, specific design for the storm sewer are provided with Final Site Plan. An overall drainage area
for the underground detention design is provided to show the area that will flow into the UGD
system.
3. Disturbed area which fronts Berkmar Drive has been included in the analysis to ensure Part IIB is met.
4. PDA has been revised per above.
5. As -Built VSMP Checklist has been included on sheet 9.
6. Sheet 9—
a. SWM facility easement has been added to this sheet
b.Slope has been decreased to below 16%
c. Inlet shaping has been identified for all structures as provided in a note on sheet 9.
d.Structures requiring safety slabs for drainage items provided in this plan are identified.
7. Drainage structure profiles for all drainage items upstream of the UGD system will be provided with
Site Plan.
8. Private SWM and maintenance easement is shown and provides a 10' landing as well as access to the
development's road.
9. Lengths have been double checked. The UGD pipes bend at the ends and that is included in the total
length to have an accurate accounting of storage and elevations as shown on sheet 9.
10. Access ladder has been provided at MH locations as shown on detail on sheet 10.
11. As noted in comment #2, all other WPO plans we've submitted do not include storm sewer
computations for storm sewer, but instead focus on the underground detention design. Storm sewer
computations are provided with Final Site Plan. Drainage design profiles from UGD to outfall has been
provided. Upstream design computations will be provided with Final Site Plan.
12. Nutrient Credit letter of availability is provided with this submission.
13. This comment is acknowledged.
14. Nutrient Credits will be purchased from Ivy Creek.
D. Erosion and Sediment Control Plan
1. Existing contours were surveyed at 2' intervals and are shown as such on the plan.
2. Sheet 5—
a. Contours are daylighted/tied-in around sediment traps.
b.Additional TS/PS labels have been added to show the intention that they are to be provided
up to the sediment basin embankment
c. B/M has been extended to back of dam slope.
d.Specific trap labels have been added.
e. Sediment trapping device has been added for the CE
f. As shown on the plan, the sediment basin has been downsized to a trap as an additional trap
has been included on the Phase II plan.
3. Shet 6/7—
a. ST#3 label has been added
b. Contours have been revised to be 2:1 or flatter. Some contour spacing may be shown closer
within footprints of building to show where basements are provided.
c. CRS has been added for the streets.
d. Note has been added to sheets 6&7.
e. As note on plan describes, silt fence has been offset from limits of disturbance for graphical
purposes, so the various linetypes can be shown.
f. Sediment trap has been provided at N/W end of site.
g. An overall grading plan has been added to the plan set as Sheet 11.
h. Sediment basin is now a sediment trap as an additional trap has been provided on Phase II
plan.
4. Channel diversion directional change has been corrected to be less than 90 degrees.
5. Outlet protection previously shown no longer applies due to sediment basin being converted to
sediment trap.
6. Spot shots and slopes have been called out on sheets 6 & 7 diversion dikes. If permanent channels
were shown on this plan, channel lining design and profiles would be provided. However, as the
diversion dikes are of a temporary nature and enough traps are provided on site that not a significant
amount of runoff will be flowing to the diversion dikes, it does not seem necessary to provide a
specific design for diversion dikes.
7. As noted in response to comment #6, as these diversion dikes are of a temporary nature it seems
unnecessary to provide a detailed analysis.
8. This note has been added to stabilize slopes steeper than 3:1 with hardier vegetations. See sheets 5-7
9. Mulching is shown anywhere there is permanent or temporary seeding. See sheets 5-7.
10. Project's cut & fill estimate has been provided on sheet 4.
11. This comment is acknowledged.
12. Retaining wall height is a maximum of 6'.
Should you have any questions, please feel free to contact Scott Collins at Scott@collins-enxineerine.com.
Sincerely,
Scott Collins, PE