HomeMy WebLinkAboutWPO201800068 Review Comments 2019-01-28 Dewberry Dewberry Engineers Inc. 804.290.7957
4805 Lake Brook Drive, Suite 200 804.290.7928 fax
Glen Allen,VA 23060 www.dewberry.com
January 28, 2019
County of Albemarle, Department of Community Development
Attn: David James, VSMP Reviewer
401 McIntire Road, Room 227
Charlottesville, VA 22902-4596
RE: ACSA Operations Center Expansion Parking Lot Expansion
2"d Re-submission
Project File Number: WPO201800068
Dear Mr. David James,
On behalf of the Albemarle County Service Authority, Dewberry Engineers Inc. is pleased to submit for
your review and approval the final plans for the ACSA Operations Center Expansion Parking Lot
Expansion revised per three(3) sets of county comments. Two(2)copies of the Final Design(100%)
plans signed November 12, 2018 are being submitted for your review. Below are the comments along
with responses (shown in bold) that were received from your review dated December 21, 2018.
C. Pollution Prevention Plan(PPP)
The PPP content requirements can be found in County Code section 17-404.
1. Show any proposed clearing/grading activities, paving operations, landscaping operations, E&S
controls, staging, stockpile,borrow, fueling, waste disposal, vehicle/equipment washing,
concrete washout locations on the PPP.
(Rev.1)Partially addressed. Show all E&SC and clearing/grading operations.Turn
off existing contours & use thicker linetype for LOD (for clarity).
(Rev. 1) Response: All ESC measures and demolition and grading activities are included
on the PPP. Existing contours have been turned off and the LOD has been more clearly
defined.
D. 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.
4. Submit the VRRM spreadsheet, pdf is fine.
a. (Rev.1)You're showing use of a MTD-Filtering that treats 0.22 Ac.The only proposed
SWM facility shown in the plans is the underground detention system and is not a
filtering device.Please revise VRRM.
(Rev. 1)Response: The Manufactured Treatment Device that was shown in the VRRM has
been removed. The total phosphorous removal required remains the same as before-0.35
Page 1 of 3
Mr.James
ACSA Operations Center Expansion Parking Lot Expansion
W P0201800068
15t Submission Comment Responses
•
lb/year, the MTD was not providing any treatment. There is no treatment provided onsite
for this project. All treatment is provided by the purchase of nutrient credits.
b. (Rev.1) In the `Runoff Volume and CN Calculations' summary table incorrect
precipitation values are given for the location per NOAA Atlas 14. Please revise
VRRM.I 11
12-hr
II (224 2.90) I (2.69-3.50) I (3.34-4.35) ,I (3.95 5 15)
24tu 3.03 3.66 4 S8 5.54
(2.72 3.40) (3.29.4.12) (4.19-5.26) (4.94 6.20) (E(E
6.48
2-may (3 20 3.99) (3.89-4.84) (4:3-6 15) (5.$n) I t�
(Rev. 1)Response:The rainfall data has been updated.
5. Sheet C6.0—Provide analysis/computations to verify the discharge values shown at the
outfall points.
(Rev.1)Partially addressed. Should the D.A.Onsite be 0.23ac,not 0.32ac(Please verify)?
(Rev. 1)Response: DA Onsite has been updated to 0.23 ac.
8. Sheet C6.3—Energy Balance worksheet shown is confusing!
(Rev.1)Sheet C6.2: `Energy Balance - Outfall 1' -Provide analysis/verification of each
outfall, where do you get your Runoff Volume (RV)values of 0.020 ac-ft (pre-dev) &
0.058 ac-ft(post-dev).Doesn't appear to correlate with VRRM(0.11ws-in)or Routing
(0.0524. `Energy Balance- Outfall 2'—Should the value be 0.08cfs (Pre-development
discharge),not 0.18cfs (Please verify)? Same thing as above,where did you get your RV
values?
(Rev. 1)Response: For both outfalls, the Runoff Volume(RV) is calculated using TR-55 to
obtain"Q (in)."The Q is multiplied by the DA(ac) and converted to get the volume in ac-ft.
The RV does not match the VRRM numbers because there are two outfalls on this project and
therefore each outfall has a different RV because of the different drainage areas.
The pre development RV for Outfall 1 (0.020 ac-ft)matches the existing site area runoff
volume calculated in Hydrocad as shown on sheet C6.3 "Existing Conditions—Ex Onsite."
The volume for the"Ex AO 1" is different because there is offsite area calculated for the
outfall because of the existing parking lot that is detained in the detention pipes.
Outfall 2-The existing flow has been updated to 0.08 cfs.The outfall meets channel
protection.
10. [New] (Rev.1)SWM easement plat & deed of dedication must be
reviewed/approved/recorded prior to VSMP plan approval.
(Rev. 1)Response: Acknowledged.
11. [New] (Rev.1)Include this checklist in the plan set.
http://www.albemarle.ore/unload/images/forms center/departments/Community Develo
pment/forms/Ent ineerine and WPO Forms/WPO VSMP Construction Record Drawi
Dewberry.
Page 2 of 3
Mr.James
ACSA Operations Center Expansion Parking Lot Expansion
W P0201800068
1"Submission Comment Responses
nes Policy 23Mav2014.pdf
(Rev. 1)Response: The checklist is included on Sheet C6.2.
E. 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 disapproved,.and the reasons are provided in the comments below. The
erosion control plan content requirements can be found in County Code section 17-402.
5. Show any offsite improvements including grading operations in a permanent easement.
Provide evidence that neighboring property owner is in agreement with this offsite work
in the easement. This can be a letter of agreement signed by neighboring property
owner. (DSM, Sect. 8C,3F)
(Rev.1)Partially addressed. Rename/show label as mentioned above on sheet C3.1.
(Rev. 1)Response: Previous discussions between ACSA and the Site Plan Reviewer resulted
in the easement being labeled"Permanent Grading Easement."This has been depicted on
Sheet C3.1.
This letter is provided as part of the resubmittal process and addresses all of the comments above. If you
have any questions or require clarification please let us know.
Sincerely,
Z7;0. iivtivIdOL
Kevin A. Pennock
ti! Dewberry Page 3 of 3