SW4200501_2020-05-27 Stormwater_5th submittal Comments_5/28/2020

CLH design, p.a.
400 Regency Forest Drive, Suite 120
Cary, North Carolina 27518
P: 919.319.6716 C L H
www.clhdesignpa.com aEsiC__N
Site Plan Comment Responses
Date: May 28, 2020
Re: Lewisville Middle School- Forsyth County - State Project SW4200501
Dear Jim Farkas :
Below in red are our responses to the 51" round of review comments received for the above referenced project.
Division of Energy, Mineral and Land Resources
Comment 1: Please include the stormwater permit number from the prior submittal, SW4191201, in Section
II, 3 of the application as this application it is being submitted as the result of a previously
returned application.
Response: Section 11.3 has been revised to include the old SW number.
Comment 2: Please ensure that the percent impervious area for the entire site is calculated correctly (Section
IV, 8).
Response: Percent impervious area has been revised.
Comment 3: Off -site drainage areas that are being considered 100% impervious should not be listed as
"Future" BUA, but rather as "Off -site" BUA (Section IV, 10 & Supplement-EZ Form, Drainage
Areas Page, Line 10). Future BUA is reserved for BUA that will be constructed on -site at a future
time and off -site BUA is for BUA that is not located within a project site.
Response: 100% impervious surface has moved to the off -site portion in impervious surface area table. The
drainage area table in the supplement-EZ form have been revised to show offsite drainage area
as offsite BUA. Sheet CO3.08 has been revised to reflect future and offsite BUA.
Comment 4: The on -site drainage area for Drainage Area 2 should be reported in square feet (Section IV, 10).
Response: The on -site drainage area has been revised to be in square feet.
Comment 5: Please include Section IV, 11 of the application. It appears to be missing.
Response: This section has been filled out and specifies 100% impervious for future build out.
Comment 6: Please include an original, signed in pen & notarized, hard copy of the O&M Agreement Form
(Section V & Section VI, 3). Since this is a new submission, new original forms must be provided
(As stated in my 5/14/2020 email, we do not keep the hard copies of returned applications).
CLH design, p.a.

Site Plan Comments
May 28, 2020
Response: Original O&M is provided with this submittal.
Comment 7: Please include an original, signed in pen & notarized, hard copy of the application
(Section VI, 1 & Section X). Since this is a new submission, new original forms must be provided.
Response: Original application is provided with this submittal.
Comment 8: Please update the cover sheet, C00.00, to reflect the revisions to the plans (Section VI, 8g).
Response: Cover sheet has been revised to show revision dates. All revised sheets have revclouds with a note
in the title block.
Comment 9: The signature in Section IX is not needed since the applicant is the property owner.
Response: This was a typo on the owner's part, this should not be an issue with the new application as a new
original has been requested.
Comment 10: Please correct the following issues with the Supplement-EZ Form:
a. Cover Page:
i. Line 2 —The project area should correspond to the total project area
reported in Section IV, 7 of the application.
Response: Supplement-EZ form has been revised to match the application.
b. Drainage Areas Page:
i. Entire Site Column —There appears to be a calculation error in this
column:
1. The items in Line 10 should add up to Line 7.
Response: Line 7 has been revised and should sum up the BUA from line 10 only.
The 100% offsite was included in this previously.
2. Lines 6, 7, & 13 should add up to Line 5.
Response: Line 5 should now equal to lines 6, 7, & 13 only and discludes the
offsite impervious that was improperly allocated as future.
ii. Line 10, Future BUA — See earlier comment. Off -site area that is
considered to be 100% BUA should be reported on Line 9 (NOTE: Offsite
areas should not be accounted for in the entire site column). It is
recommended that the BUA tables on plan sheets CO3.07 & CO3.08
include an "Off -site BUA" row.
Response: Line 9 has been revised to indicate off -site 100% impervious. Offsite is
left not shown in the entire site column as noted. Off -site column has
been added to sheet CO3.08.
iii. Drainage Area 1:
1. Line 16 —This item does not match Section IV, 10 of the
application. Revise as needed.
Response: The supplement-EZ form has been revised to match the
application.
2. Line 18—This item does not match the calculations or the Wet
Pond Page. Revise as needed.
Response: This line has been revised.
c. Wet Pond Page:
i. Revise as needed in accordance with the other comments.
Response: Wet pond sheet wasn't revised.
d. Stormwater Wetland Page:
i. Revise as needed in accordance with the other comments.
CLH design, p.a.

Site Plan Comments
May 28, 2020
Response: Wetland areas and percentages were revised per comments below.
Comment 11: Please show the elevation of the top of the sediment storage area on the cross-section for
the wet pond on sheet C07.04.
Response: Cross section has been revised to show a dashed line illustrating the sediment storage and have
added language to both the forebay and main pool for the top of sediment storage. This is the
same as the bottom of the MP/FB so it will read "main pool bottom/sediment storage top" as an
example.
Comment 12: Sheet C07.04 shows the width of the vegetated shelf as 6 ft, the slope of the vegetated
shelf as 10:1, the bottom elevation of the shelf as 826 and the top elevation of the shelf as
827. Please revise for consistency.
Response: The slope has been revised to 6:1 on sheet C07.04.
Comment 13: The forebay surface area (630 sf), non-forebay deep pool surface area (590 sf), and
shallow water zone surface area (1,690 sf) are greater than the total surface area of the
stormwater wetland at the permanent pool elevation (630 sf+ 590 sf+ 1,690 sf = 2,910 sf
> 2,610 sf). Please revise and provide a stage -storage table for the stormwater wetland.
The stage -storage table should include elevations from the lowest point of the stormwater
wetland (The forebay entrance @ elevation 809) to at least the temporary pool surface (@
elevation 812.71) at useful intervals (such that important benchmarks, like the bottom of
the shallow water zone, permanent pool, and the top of the temporary inundation zone are
shown). The cross -sectional area of the stormwater wetland should be shown at each of
these elevations (In situations where the cross -sectional area is split between two zones,
such as the forebay and non-forebay deep pool, the cross -sectional area column can be
divided by type). See below for an example:
Response: The wetland zones on the sizing spreadsheet has been revised. The DP, FB, and shallow water
now sum up to the Permanent pool surface area. Additionally a stage storage table has been
provided similar to the example provided and should spell out the zone's. The stage storage
exhibit, the wetland sizing calc and the supplem en t-EZ form should all be consistent with this
revision.
Comment 14: The shallow water zone encompasses all portions of the stormwater wetland between 0
and 9 inches below the permanent pool surface elevation. Therefore, the shallow water
zone must be 9 inches deep (Stormwater Wetland MDC 8). Please revise accordingly.
Response: Shallow water zone on the wetland detail sheet, C07.05, has been revised to an elevation of 9"
below PPE or 811.25. Additionally this is spelled out in the stage storage chart requested above.
Comment 15: The total quantity of plants shown in the shallow land plant list on plan sheet C07.06
does not equal the sum of the individual plant quantities (66 + 66 + 66 + 66 + 67 # 428).
Please revise (Stormwater Wetland MDC 12c).
Response: This was a typo and has been resolved. The plant quantities have been revised due to the
revisions made in the previous comments.
Comment 16: Provide pdfs of all revisions, 2 hardcopies of revised plan sheets, and 1 hardcopy of other
documents. Pdfs must be uploaded using the form at:
https://edocs.deq.nc.gov/Forms/SW_Project_Submittal
CLH design, p.a.

Site Plan Comments
May 28, 2020
Response: PDFs and hardcopies of all revised plans are provided with this submittal.
Comment 17: NOTE: Please upload the initial (5/20/2020) submittal information at the above link
using the "SW4200501" permit number.
Response: These files were reuploaded under the new SW number on May 261n
End of Responses
Thank you for all your help and please call with any questions.
Sincerely,
For CLH design, p.a.
Renee Pfeifer, PLA
Vice President
CLH design, p.a.