SW4191201_2020-01-31 Stormwater Comment Response_1/31/2020

CLH design, p.a.
400 Regency Forest Drive, Suite 120
Cary, North Carolina 27518
P: 919.319.6716 C L H
www.clhdesignpa.com a Es 1 C71 N
Site Plan Comment Responses
Date: January 31, 2020
To:
From:
Re: SW4191301 - Lewisville Middle School
Dear Jim Farkas:
Below in red are our responses to the 1st round of review comments received for the above referenced project.
Division of Energy, Mineral and Land Resources (DEMLR)
Comment 1: The provided project coordinates appear to be for an adjacent property (Section 1, 4). Please ensure
that the project coordinates correspond to the project location.
Response: Coordinates in section 1.4 have been revised. This reflects coordinates center to the site.
Comment2: Please provide official documentation showing that Colon Moore can sign on behalfof the Winston-
Salem /Forsyth County Board of Education (Section 111, 1a).
Response: A memo from the school system has been included with this submittal.
Comment 3: While the information is appreciated, the pre -construction and post -construction site conditions are
not required in this table (Section IV, 10). Please only include the drainage areas to the proposed
SCM's.
Response: Pre- and post -construction site conditions have been removed from this table in section IV.10.
See revised application.
Comment 4: Please show the square footage of the surface water area in the land use table on sheets CO3.07 &
CO3.08 (Section VI, 8h).
Response: Square footage of surface water area has been added to the legend/area table on each map.
See revised sheets CO3.07 and CO3.08.
Comment S. Please delineate the wetlands on the plans or provide a note stating that no wetlands exist. Provide
documentation of the qualifications and identity of the individual who made this determination
(Section VI, 8m).
Response: A note has been added to state that no wetlands exist.
CLH design, p.a.

Site Plan Comments
January 31, 2020
Comment 6: Please provide a stage -storage table for the main pool and forebay sections of the proposed wet
pond so that the pond sizing calculations may be verified.
Response: Additional stage -storage info has been added to the front end of the hydraflow routing report.
This will include a stage -storage for the main pool and a separate stage -storage for the forebay.
Comment7. Please provide a stage storage table for the portion of the stormwater wetland that is above the
permutant pool elevation so that the drawdown calculations can be verified.
Response: Stage -storage tables can be found in the supporting calculations tab of the stormwater
narrative. In the table of contents for the hydraflow report see "Pond Report - SCM 1 " on page 8
and "Pond Report-SCM2" on page 12.
Comment 8: There appears to be a discrepancy between the wetland zones shown on sheet C07.06 and the zones
shown on the Supplemen t-EZ Form and the calculations (For Example, the deep pool zone on the
plan sheet is shown as 270 sf while it is shown on the Supplemen t-EZ Form and calculations as 590
so. Please revise forconsistency.
Response: Sheet C07.06 has been revised to have the correct area.
Comment 9: Please show the stormwater maintenance access on the plans (General MDC 8).
Response: Stormwater maintenance access easements have been added. Please see sheets CO3.03 &
CO3.04.
Comment10: PleaseaddressthefollowingontheSupplement- EZForm:
a. Drainage Areas Sheet
i. Line 7- This item is the net increase in BUA (post -construction BUA -pre-construction BUA) for
either the entire site or the drainage area to the proposed SCM.
Response: See sheets CO3.07 and CO3.08 for revised land use maps. Areas for SCMs have been added so
the net change could be verified. Supplement-EZ has been revised.
ii. Line 10 - This item is the net increase in BUA (post -construction BUA -pre-construction BUA) for
either the entire site or the drainage area to the proposed SCM, broken down by type.
Response: See sheets CO3.07 and CO3.08 for revised land use maps. Areas for SCMs have been added so
the net change could be verified. Supplement-EZ has been revised.
iii. Line 13 - This item is equal to the lesser of the post -construction BUA or
the pre -construction BUA (for either the entire site or the drainage area to the proposed SCM). For
this project, Line 13 + Line 7 = Line S.
Response: See sheets CO3.07 and CO3.08 for revised land use maps. Areas for SCMs have been added so
the net change could be verified. Supplement-EZ has been revised.
iv. Line 15 - This item is the net decrease in the BUA from pre -construction
to post -construction, ifopplicable. For this project, Line 13 + Line 15 = Pre -construction BUA.
Response: See sheets CO3.07 and CO3.08 for revised land use maps. Areas for SCMs have been added so
the net change could be verified. Supplement-EZ has been revised.
CLH design, p.a.

Site Plan Comments
January 31, 2020
v. Line 19 - The design volumes should be calculated using either the Simple Method or the Discrete
NRCS Curve Number Method (Refer to the Stormwater Design Manual, Part B).
Response: This has been revised to the simple method.
b. Wet Pond Sheet
i. Line 44 -The forebay exit must be shallower than the forebay entrance (Wet Pond MDC 5).
Response: Forebay entrance in Supplement-EZ has been revised to 60-inches. The exit is drawn to be 6-in
less at exit.
ii. Line 47- The plans indicate that the vegetated shelfslope is 10:1 whereas
the Supplement-EZ Form indicates that it is 6:1. Please revise for consistency.
Response: Supplement-EZ form has been revised to be 10:1.
c. StormwaterWetland Sheet
i. Line 8 - There appears to be an overflow/bypass incorporated into the
design (General MDC5).
Response: The supplement-EZ form has been revised to say "yes".
ii. Line 28 - The forebay exit must be shallower than the forebay entrance
(Stormwater WetlandMDC6).
Response: Supplement-EZ has been revised to show 30-inches at forebay entrance and
24-inches at forebay exit.
iii. Line 49 - Soil amendments must be done to a depth of 12 inches, if
required (StormwaterWetland MDC4).
Response: A note has been added to detail sheet C07.05.
Comment 11: Provide pdfs ofall revisions, 2 hardcopies ofrevised plan sheets, and 1 hardcopy of other documents.
Pdfs must be uploaded using the form at. https.Iledocs.deq.nc.gov/Forms/SW Project Submittal
Response: Revisions have been uploaded and hard copies have been provided.
End of Responses
Thank you for all your help and please call with any questions.
Sincerely,
For CLH design, p.a.
Hannah Banks
Civil Designer
CLH design, p.a.