HomeMy WebLinkAboutWPO201900062 Correspondence 2021-08-02f•�eas
608 Preston Avenue
P 434.295.5624
Suite 200 IF434.295.1800
T I M M O N S GROUP
Charlottesville, VA 22903 www.timmons.com
July 29, 2021
Matt Wentland
Albemarle County Community Dev.
401 McIntire Rd, Rm. 227
Charlottesville, VA 22902
RE: Southwood Village -Amendment 1 - VSMP Permit Plan Review — WP0201900062 —
Comment Response Letter
Dear Mr. Wentland:
We have reviewed all of your Rev. 1 comments dated July 22, 2021 and made the necessary
revisions. Please find our responses to the comments below in bold lettering.
A. Stormwater Pollution Prevention Plan (SWPPP)
The SWPPP content requirements can be found in County Code Section 17-405. A SWPPP
must contain (1) a PPP, (2) an ESCP, (3) a SWMP, and (4) any TMDL measures necessary.
1. Update the on -site SWPPP with this amendment once approved.
The on -site SWPPP will be updated with this amendment once approved.
Rev. 1 Response noted.
B. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code Section 17-404.
1. Update the on -site PPP with this amendment once approved.
The on -site PPP will be updated with this amendment once approved.
Rev. 1 Response noted.
C. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a
SWMP. This plan is disapproved, and the reasons are provided in the comments below. The
stormwater management plan content requirements can be found in County Code Section
17-403.
ENGINEERING I DESIGN I TECHNOLOGY
1. This plan cannot be approved until the additional 0.48 Ib/yr of nutrient credits have
been purchased. Please contact Ana Kilmer prior to purchasing credits. Once the total
load reduction required reaches 10lb/yr, between this project and all others on the
property, 75% of the reductions will need to be achieved on -site (9VAC25-870-69(B)3).
DEQ has also updated their credit purchasing requirements, located in 9VAC25-900-
91(B)3. Since this project drains to impacted streams, the credits will need to be
purchased from a bank located in the same 8-digit HUC. The process goes upstream,
then HUC12, HUC10, and HUC8, at which point the Ivy Creek credit bank is in the same
HUC8. The credits will need to be purchased from the Ivy Creek bank unless you have a
Letter of Credit Availability dated prior to January 1, 2021.
A Letter of Credit Availability has been emailed to Ana Kilmer on May 26, 2021.
Rev. 1 Response noted.
2. The maximum side slopes allowed by the County inside a basin is 3:1.
The basin has been revised to have a maximum of 3:1 side slopes.
Rev. 1 Comment partially addressed. The max height of retaining walls per the Code of
Development is 6'.
Single retaining wall has been revised to two shorter walls, each with a V maximum height.
3. Provide details for the retaining wall located in the stormwater basin. Show the TW and
BW and note whether the wall is below the water level during design storms.
The top and bottom of wall elevations have been added to sheet C3.03. The eastern and
western walls both have a proposed bottom elevation of 424.10 which is higher than the crest
of the primary outfall elevation of 432.92. It is anticipated that the WSE will only be greater
than 424.10 during 10-year storm events and greater.
Rev. 1 Since the wall will be partially submerged, provide stamped wall plans showing this in
the design.
Structural design of walls will be provided prior to construction. Walls have been added to Dry
Pond Detail on sheet C6.01, to clarify to structural designer that walls will be partially
submerged during certain rainfall events.
4. Provide fence and or railing around the proposed pond, as it is located close to
backyards and adjacent to the proposed trail.
A fence has been added around the proposed pond. Note, safety railing has also been
specified on the proposed retaining walls.
Rev. 1 Comment addressed.
5. Update the bioretention details on Sheet C6.01. The forebay in bioretention 1 also
appears to be too small.
The bioretention details have been updated on sheet C6.01. The forebay in Bioretention 1 has
been resized accordingly.
Rev. 1 Comment addressed.
6. The post-dev drainage area map on C6.00 appears to be incorrect. It shows the DA to
structure 302 going to bioretention 1, however 302 goes to bioretention 2. It also shows
the drainage from the southern half of Wardell Crest going to bioretention 1, but the
pipe system bypasses the bioretention. Please verify and correct as needed.
The post -developed drainage areas have been re-evaluated and revised as needed to ensure
they accurately depict the contributing drainage area. Details, summaries and calculations
book has been updated accordingly as well.
Rev. 1 Comment addressed.
7. Update the water quality narrative in the calculations package.
The water quality narrative in the calculations package has been revised.
Rev. 1 Comment addressed.
8. Per the Code of Development, residential lots are to be located outside of stream
buffers, preserved slopes, and floodplains. Several lots on Wardell Crest will need to be
revised.
Lots along Wardell Crest have been revised to be outside of the stream buffers, preserved
slopes, and floodplains.
Rev. 1 Comment partially addressed. The exhibit for the preserved slopes as discussed with the
site plan will need to be submitted and approved before this plan is approved and disturbance is
allowed in those areas.
Critical slope exhibit has been included with this submittal.
9. Detail how the roof drain discharge will be handled on the backs of the lots. A
concentrated flow to steep slopes is not recommended.
A note has been added to sheet C6.00 stating, "Downspout splash blocks shall be used for all
roof drains."
Rev. 1 Comment addressed.
D. Erosion and Sediment Control Plan (ESCP)
Virginia Code 62.1-44.15:55 requires the VESCP authority to approve or disapprove an ESCP.
This plan is approved, and the reasons are provided in the comments below. The erosion
control plan content requirements can be found in County Code Section 17-402.
1. The match lines between sheets do not appear to match. Portions of SB1 are not shown.
Match lines have been revised to match between sheets. All SBl contours are shown. Please
note that there is a retaining wall around SB1.
Rev. 1 Comment not addressed. Please refer to SB1 on Sheets 3.03 and 3.05, where portions of
the grading, labelling, and limits of disturbance are cut off at the top of the sheet.
Extents of sheets C3.03 and C3.05 have been revised to include entirety of SB1/Dry Pond.
Match lines have been updated accordingly.
We have included PDF copies of the plans and calculations for your review. If you have any
questions or comments, please feel free to email me at clint.shifflettC@timmons.com .
Sincerely,
Clint Shifflett, PE
Project Manager