HomeMy WebLinkAboutWPO201800044 Correspondence 2022-01-28 (2)SHIMP ENGINEERING, P.C.
Design Focused Engineering
January 27, 2022
John Anderson, PE
County of Albemarle
Department of Community Development
401 McIntire Road, North Wing
Charlottesville, Virginia 22902
RE: Response Letter #1 for WP02018-44 ABC Block 1 Mass Grading — Major Amendment for
Multifamily
Dear John,
Thank you for your review of the VSMP Plan for Albemarle Business Campus Block 1. This letter
contains responses to County comments dated January 7, 2022. Your comments are listed in grey below,
our response are listed in bold.
A. Stormwater Pollution Prevention Plan (SWPPP)
1. Replace on -site SWPPP, WP0201800044 Amendment #1, with SWPPP submitted with
\pplication, once items at item 2, below, are addressed.
Noted, this will be completed.
came,
a. Please revise Registration statement at p. of SWPPP/.PDF to indicate Application type is
Modification with acreage increase as this registration will he used to notify DEQ to
increase Estimated Area to be disturbed from current 4.50 Ac. to 5.40 Ac. (VAR10P436).
Note: DEQ will send request for payment of state permit to operator email listed at
Sec. 1. B.
Noted, Registration Statement revised to check "modification with acreage
increase", see updated SWPPP.
b. Revise SWPPP cover to reference Amendment r_
Noted, see updated SWPPP.
B. Pollution Prevention Plan (PPP)
No request for revision to PPP Exhibit.
C. Stormwater Management Plan (SWMP)
1. Application Fee: $1,700 fee was received 12/14/2021. Fee for land disturbance 5 and less than 10
acres is $2,004.08. Please submit $304.08 balance at earliest convenience.
304.08 balance paid with this resubmission. See attached receipt.
2. C5: Show discontinuous curb (curb cut) at Sir. A4 if this structure is to receive parking lot runoff.
This structure A4 is not intended to receive runoff, rather it is an overflow measure for the
BMP's.
3. C6: Wherever storm runoff concentrates against curbing, provide and label CG-6.
CG-6 provided at curbing which receives runoff.
912 E. High St. Charlottesville, VA 22902 1434.227.5140 1 shimp-engineering.com
4. CT
a. Detail 8: Provide linework and label/s to indicate connection with BMP-I.
Label added to show connection.
b. Show building roof leader collection system connection with MH structures in storm
drain profiles at Str. CIA, D2, 13213, E2, etc. Provide leader line collection DIV IN at MH
structures to aid construction and inspection.
Roof drains "invert in" are now listed on profiles where these drains enter
manholes.
c. Provide trash rack detail (weir plat orifices).
Trash rack details provided.
d. Pro, ,n nC; Oqq for MH Str. A4.
Stairs are now labelled, as are inflow/outflow pipes/
e. ChcL, ,.-, _ : -- . ctail vertical dimension, may need to revise to 8.4� .
This was a typo, detail has been corrected, then revised to optimize for peak flow
rate, peak WSE, and better maintenance parameters.
f. Show Sir. El to BMP-1 connection (use labels /linework).
Label added to show connection.
5. Provide SWM facility , I Easements must be reviewed, approved and recorded prior to
Amendment #2 approval.
SWM facility easements provided.
6. C 17: Provide sheet title (ex.: Pre -development ground cover) to indicate sheet depicts pre -
development (existing) land cover since turf with limited forest approximates Amendment #1
post -developed condition.
Sheet Title for C17 corrected.
7. C20: Sir. CIA spread appears excessive; recommend increase inlet throat length.
C1A had inaccurately large drainage area to inlet (was designed before roof drains were
added), so the LD-204 flow has reduced, therefore the spread is reduced and now
reasonable without throat length revision.
8. Calculations /p. 2-3: Pi_ )it request with $272 exception review fee. Copy
narrative from Calc. packet (p. 2-3) to separate exception request letter. Recommend refer to
RGA design fain request, 23 Apr 2021, as an example, when requesting exception to 3.0"
minimum orifice size. Use 1-year storm event (not Q1.5, Q2, Q10) for purpose of comparing
various orifice DIAs with applicable Q I Max. EB, and please especially note proposed Q I post-
dev PA2 (0.70cfs; orifice DIA=3.0"), state that 3.0" provides 92% of target EBE-generated
reduction, and last, please specify orifice diameter size otherwise required to meet EBE.
Engineering will likely not object to request, but exception request entails separate review
/approval.
Exception request (and fee) have now been provided as separate document. Narrative
updated per exception request language.
9. Revise Calc. packet cover a 211dment #2.
Cale. packet cover letter updated to reference amend. 2.
10. Plan proposes 1.64 lb. nutricc..redit purchase. Purchase is not required for plan approval, but
nutrient credit purchase is required prior to commencing land disturbance unique to Amendment
#2.
Client is expected to complete this purchase in February, will forward affidavit and bill of
sale to you and Ana Kilmer when received.
912 E. High St. Charlottesville, VA 22902 1434.227,51401 shlmp-engineering.com
D. Erosion and Sediment Control Plan (ESCP)
1. C2:
a. Label Country Green Road, Old Lynchburg Road, and Mountainwood Road.
Labels added to this sheet, and elsewhere.
b. Provide deed bk.-pg. ref. to RW for public roads listed at item a., above.
References added to this sheet.
2. C5: Please label outfall protection dimensions at Str. Fl: L x W x D.
Outlet protection dimensions added to this sheet.
3. C11: Paragraph with four itemized work activities (L-4.) under Project Description appears to
reflect WP0201800044 Amendment 1 activities, rather than apartment construction; update work
activities, as needed.
This narrative paragraph has been updated.
4. C13: Show parking lot inlet protection JP) in phase 2. C11 sequence indicates curbing acts as
diversion, once curbing is installed in phase 2.
You are correct, IP now added to phase 2.
5. C15:
a. Increase volume of 5 I 1, similar to increased volume under Amendment #1, given
proximity to 07600-00-00-046C1 (Mountainwood Properties) and relative likelihood of
off -site impact if Vol. provided is barely > minimum Volume required.
This is sensible, ST1 has now been oversized by 20 %.
b. Provide sediment trap design data for Phase 1, trap 2. Volumes differ; elevations differ.
Phase 1 trap data (current sizing, from Amendment 1 mass grading, had been
missing in plans) now provided on C12.
If you have any questions or concerns about these revisions, please feel free to contact me at
keane@shimp-engineering.com or by phone at 434-299-9843.
Regards,
Keane Rucker, Err
Shimp Engineering, P.C.
912 E. High St. Charlottesville, VA 22902 1434.227,51401 shlmp-engineering.com