HomeMy WebLinkAboutWPO201800088 Review Comments 2019-05-23PROJECT MANAGEMENT
5HIMCIVIL ENGINEERING
LAND PLANNING
ENGI N EERI NGa
May 23, 2019
Mr. David James
Department of Community Development
401 McIntire Road
Charlottesville, VA 22902
RE: WPO 201800088 Pantops Corner VSMP
Dear David,
Thank you for your review of the revision of the VSMP Plan for Pantops Corner We have revised the plan
per the your most recent comments dated May 20, 2019. See below for detailed responses to each of your
comments.
A. SWPPP
B. PPP
C. SWMP
Calc Booklet
6. Device 5 is the area above the weir plate, which is a 8' wide by 3' rise opening to the top of the CMP stub.
Device 4 models the 12" wide weir, which extends 2.28' to the top of the plate. The HydroCAD model
correctly reflects the plans.
7. Undetained areas revised.
a. Note on undetained area added to predev DA map. Predev DA slightly revised per request to
include drainage from areas outside the boundary line.
b. All development area has now been accounted for. The sheetflow runoff from the back of the
property has been added to POA 1 in the maps and HydroCAD model. The runoff at the front
of the property has been added to the maps. Since this front runoff discharges into the
Rivanna River, where it meets the 1% rule, this area's analysis is covered in the Rte 250 inlets
section which demonstrates that the system contains the 10-year storm.
Please note that the 7.25 acre limits of disturbance is not the governing area for
stormwater analysis, as portions of existing land cover within the limits of disturbance will not
be changed. For example, the area within the current Rte 250 and Rte 20 road pavement, the
area where the rip -rap outfall will be improved, and the area near the retaining wall gn parcel
5C. These areas are included in the limits of disturbance, as the contractor will need to
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operate construction vehicles in these areas here but will not alter the land cover of these
locations.
Instead, we will provide quality and quantity treatment for the development area which
includes the onsite area plus the area of right-of-way improvements. This area is 6.82 acres
and complies with water quality and quantity requirements.
Plan
12. LD-204 now included on C12. LD-229 moved to this sheet as well.
13. SWM Narrative is already included on Sheet C6.
a. Quality compliance is in the narrative (Stormwater Management Narrative note 3). Letter of
availability is included in the SWM calculation packet.
b. Quantity compliance is in the narrative (Stormwater Management Narrative note 2)
C3
22. Downspouts are anticipated where roof drains are not shown. The planned roof drain locations are shown
for the self -storage building on parcel 5E.
C5
28. Per engineering meeting on 5/23/19, we agreed that nutrient credits must be purchased and documented
before issuing disturbance permit but can be completed after plan approval (as is done with SWM/E&S
bonds). We will provide nutrient credit purchase information as soon as completed.
29. Comment noted, see notes added to C11. Inspection frequency is listed on C6.
C11
C12
k. Detail updated, all now have 18" height.
o. Easement label for the detention system revised to "New SWM Esmt". Outfall included in
easement.
p. Pending approval of easement plat SUB 201900059.
r. Per engineering meeting on 5/23/19, we agreed that an underdrain is not necessary. We have not
designed the stone bed under the pipes to provide storage and have excluded the stone bed
under the pipe invert from the storage area in the HydroCAD model. Any water within the stone
bed under the pipe invert will eventually soak into the underlying soil. All water above the invert
will drain thru the 7.5" orifice.
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41. Design storm elevations extended to weir plate detail. We have shown the 30" pipe out on the barrel 1
detail. However, we cannot show invert elevation of 15" orifice coming into the detention, as it would be
shown in the wrong location (15" pipe enters via barrel 7, not barrel 1). Instead, this information is shown
in Profile 6 on C10.
42. We have moved the riser location and shifted the system a few feet to allow this riser to be placed in the
grass per engineering request.
D. ESCP
C7
5. Comment noted
6.
C8
8. Plans updated with note specifying low maintenance ground cover.
C2
11. Noted, see updated plans/notes on C7.
Included with this letter you will find a VSMP application, 2 copies of the VSMP plan, and 2 copies of the
calculation packet. If you have any questions or concerns about these revisions please feel free to call me at (434)
299-9843 or email Justin Shimp at Justin@shimp-enRineering.com and we can discuss any questions that you may
have in further detail.
Best Regards,
Keane Rucker, E.I.T.
Shimp Engineering, P.C.
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