SW6230502_Response To Comments_20231004

4006 Barrett Drive,Suite 104
ovvrna n Raleigh,North Carolina,27609
TEL [phone]
Project: Ducks Landing
Location: Darroch Road,Lillington,Harnett County
Jurisdiction: NCDEQ
Date: 6/8/23
Subject: SW Comments SW6230502
1.Application Response
2x hard copies of the Application with the following corrections made: V Application,Suuplement-EZ and stormwater management
report have been revised to 109.668 acres.
1) Drainage Area Information—Lines 5-7: Per notes on the existing
conditions and grading plans,the total tract area is 4,777,138.08
SF/109.668 acres,this is not consistent with the property
information on the application (109.723)or the Stormwater
Management Report(107.299 ac).The Supplement-EZ lists the total
drainage area of the site as 4,670,880 SF(107.23 ac),the drainage
area of the entire site,should include the entire site. If the correct
value of the site area is 4,777,138.08 SF, Line 6 should reflect this
value. Offsite drainage area may be bypassed from the site and can
be noted in Line 7.The total drainage area is the sum off the offsite
and onsite drainage area (Line 5). Please revise the application,
Supplement-EZ and report for consistency.
2.Supplement-EZ Response
lx hard copy of the complete,original Supplement-EZ Form with the V Supplement-EZ Form has been revised.
following corrections made(This item is required per Sections V& VI, 3 of
the Application):
1) Wet Pond, Line 34—The cleanout depth for the forebay is listed as
36 inches, but the plans show the stop of the sediment storage in
the forebay at an elevation of 182.0 with the bottom of the
sediment storage elevation at 181.0 in the deepest portion. Please
revise for consistency. Per 15A NCAC 02H .1053(5)(d),the cleanout
must occur when sediment accumulates in the forebay in a manner

4006 Barrett Drive,Suite 104
ovvrrian Raleigh,North Carolina,27609
TEL [phone]
that reduces its depth to less than 75%of its design depth.SCM 5
should also be revised in a similar manner.
3.Plans Response
2x signed&sealed hard copies of a plan sheets showing the following(This ✓
item is required per 15A NCAC 02H.1042(2)(g)and per Section VI,8 of the
Application):
1) A Stormwater SCM Easement was not included for SCM 3 on sheet 1) Easement has been shown.
C-11,please show the Easement to the ROW.This is required by
15A NCAC 02H.1050(8 and 9).
2) Please show the whole drainage area that is being served by SCM 1. 2) Entire drainage area has been shown.
Currently a portion of the drainage area is outside of the viewport on
sheet C-11.This is required per Section VI, 8o of the Application.
3) The"Rip-Rap Forebay"detail on sheets SCM-1,SCM-2,and SCM-3 3) Rip-rap forebay dimensions have been provided,
notes"Length and width dimensions to be per rip-rap apron detail," satisfying the pretreatment requirement for the
but a detail could not be found.EC-1 shows rip-rap dissipator infiltration systems.
dimensions for rip-rap dissipaters 1-3,but labels on plans identifying
dissipators were not apparent.Please indicate the dimensions of the
rip-rap forebay on the SCM detail sheets.Pretreatment is required
per MDC for Infiltration Systems(4).Per our phone conversation on
6/8/2023,if the Rip-Rap Forebay is dimensioned,this will satisfy the
Administrative Completeness comment concerning pretreatment.
4.Calculations Response
lx signed and sealed calculations showing the following(This item is ✓
required per Section VI,7 of the Application):
1) Please revise the"Impervious Area Summary—Infiltration Basin 1) SCM 3 Table has been revised.
SCM 3"table in the overview. (10,138 SF+28,000 SF=38,138 SF
<39,138SF)

4006 Barrett Drive,Suite 104
ovvrrian Raleigh,North Carolina,27609
TEL [phone]
2) For all SCMs-Per 15A NCAC 02H.1050(4),the inlets of SCMs 2) Erosion calculations have been provided.
shall be designed to protect the SCM from erosion resulting from
stormwater discharges.Please provide engineering calculations
demonstrating this requirement has been met.
3) For SCM 4 and SCM 5,per 15A NCAC 02H.1053(5)(c):The water 3) Forebay berm liner and calculations have been
flowing over or through the structure that separates the forebay from provided.
the main pool shall flow at a nonerosive velocity.Please provide
engineering calculations confirming this rule is satisfied.
4) For SCM 4 and SCM 5,the outlets of SCMs shall be designed so 4) Erosion calculations have been provided.
that they do not cause erosion downslope of the discharge point
during the peak flow from the 10-year storm event as shown by
engineering calculations per 15A NCAC 02H.1050(4).