SW6231107_Response To Comments_20240813

ENGINEERS 9
PLANNERS ♦
SURVEYORS
July 11, 2024 MOORMAN,KIZER&REITZEL,INC.
115 Broadfoot Avenue
Ms. Brianna Holland P.O.Box 53774
Stormwater Engineer Fayetteville,North Carolina 28305
DEMLR Post-Construction Stormwater Program [phone]
[e-mail] Fax:[phone]
www.mkrinc.com
[phone]
For Fed Ex/UPS:
512 N. Salisbury Street, Office 625Y
Raleigh, NC 27604
For USPS:
1612 Mail Service Center
Raleigh, NC 27699-1612
Re: Stormwater Permit No. SW6231107
High Density Subdivision—2 Wet Ponds
Kingston Village, Hoke County
Dear Brianna:
We have addressed your comments per your 6/13/2024 letter and updated the drawing set to reflect
these changes. Below you will find your comments listed along with our responses in blue. Included with
this letter are the accompanying calculation tables, NCDEQ forms, and revised drawings. Please don't
hesitate to call or email with any additional questions or concerns.
1. Please correct the following issues with the Supplement-EZ Form:
a. Cover Page—Line 7-8: While there is no surface water, and therefore no vegetated
setbacks associated with this project, please fill in. Per 15A NCAC 02H .1017 (10), the
vegetated setback shall be at least 30 feet in width.The vegetated setback must
remain vegetated.
Lines 7 and 8 have been updated to 30' and Yes.
b. Drainage Areas Page—Please click "Click to Load Form" in order to load the form and
complete.
This has been completed. Please find the Drainage Areas page included with this
submittal.
c. Wet Pond Page, Line 25—The temporary pool elevation is the invert of the lowest
bypass device, please revise.
Line 25,temporary pool elevation, has been updated to reflect the invert of the lowest
bypass device.This is 246.75 for Pond A and 250.00 for Pond B.
Kingston Village,SW6231107 Responses to NCDEQ Comments, Page 1 of 3

d. Wet Pond Page, Line 35—The minimum treatment volume was provided. Please see
comment later regarding the design volume.
Line 35, design volume, has been updated to reflect design volumes at pool elevations
of 246.75 for Pond A and 250.00 for Pond B. These volumes are 59,308 cf and 10,336
cf.
e. Wet Pond Page, Line 37, Wet Pond B, Please revise to 1.5"
This has been updated.
f. Wet Pond Page, Line 40—Please revise per later comment.
The drawdown times have been updated on line 40.They are 2.25 days for Pond A and
2.92 days for Pond B.The calculations are included with this letter.
g. Wet Pond Page, Line 42—This item is for berms/baffles not used in the creation of the
forebay,this does not seem to be provided per the plans. Please revise the
Supplement-EZ.
This has been updated.
2. Per Wet Pond MDC(3), The inlet(s)and outlet shall be located in a manner that avoids short
circuiting. Wet Pond 1 has an inlet that bypasses the forebay, and therefore creates short
circuiting. Please provide an additional forebay.The other forebay may need to be resized in
order to ensure that MDC 5(a) can be met. It is recommended to size the forebays
proportional to the relative drainage areas.
An additional forebay has been added to Pond A. MDCS(a) is met at 19.86% as shown
in the additional information included with this letter.
3. Provide separate tables for the volume stored beneath the permanent pool, and the volume
stored between the permanent pool and temporary pool so that sizing calculations can be
verified.
a. Ensure that the design volume (the volume between the temporary pool elevation and
permanent pool elevation)shall draw down to the permanent pool level between two
and five days, per Wet Pond MDC 7.The provided calculations appear to use the
minimum treatment volume instead of the design volume to determine the drawdown
time.The design volume is the volume stored between the permanent pool surface
(example: Wet Pond A= 245') and the invert of the lowest bypass device (example: Wet
Pond A= 246.75'). Please include the area of the temporary pool in the stage storage
calculations so that the volume can be verified. Please provide the head used for the
drawdown calculations. Part B of the manual can provide additional guidance.This is
required per Wet Pond MDC 7.
Kingston Village,SW6231107 Responses to NCDEQ Comments, Page 2 of 3

Included with this letter are stage/area/storage tables for each pond, separated per
forebay, permanent pool, and temporary pool. Drawdown calculations are shown for
each pond, 2.25 days for Pond A and 2.92 days for Pond B.
4. Per Wet Pond MDC 11(b)specify the number of plants to be planted. Provide the area of the
vegetated shelf so that the density can be confirmed.
The area of vegetated shelf and total plants required has been added to the detail
drawing sheets 22 and 23 for each pond.These are included with this submittal.
Please don't hesitate to call or email with any additional questions or concerns.
Sincerely,
David Despeaux,PE
Moorman,Kizer&Reitzel,Inc.
115 Broadfoot Avenue
Fayetteville,NC 28305
910-484-5191
[e-mail]
Kingston Village,SW6231107 Responses to NCDEQ Comments, Page 3 of 3

Pond A
Forebays#1 and#2
2 volume above the
elev(ft) area (sf) volume (cf) 2 volume (cf) 240' sed. storage (cf)
239.25 193.12
239.50 2,748.95 367.76 367.76
240.00 2,926.44 1,418.85 1,786.61
241.75 3,551.66 5,668.34 7,454.95 5,668.34
244.50 4,862.68 11,569.72 19,024.66 17,238.05
245.00 5,418.79 2,570.37 21,595.03 19,808.42
*Areas and volumes are provided for the sum of the forebays. Forebay#1 min.elev. is at
239.25, Forebay#2 min. elev. is at 241.75.
19,808.42cf is 19.39%of the 102,135.03cf in the permanent pool.
Permanent Pool
1 volume above the
elev(ft) area (sf) volume (cf) 2 volume (cf) 240' sed. storage (cf)
239.50 16,050.37
240.00 16,772.75 8,205.78 8,205.78
244.50 23,274.19 90,105.62 98,311.40 90,105.62
245.00 24,843.44 12,029.41 110,340.81 102,135.03
Temporary Pool
elev(ft) area (sf) volume (cf) 1 volume (cf)
245.00 30,262.23
245.50 33,355.80 15,904.51 15,904.51
246.75 36,090.48 43,403.92 59,308.43
249.00 41,012.90 86,741.30 146,049.73
249.30 49,128.30 13,521.18 159,570.91

Pond B
Forebay
1 volume above
elev(ft) area (sf) volume (cf) sed. storage (cf)
242.5 123
248 696 2,252.25 2,252.25
248.5 850 386.50 2,638.75
2,638.75cf is 17.78%of the 14,842.44cf in the permanent pool.
Permanent Pool
1 volume above
elev(ft) area (sf) volume (cf) sed. storage (cf)
240.5 44
242.5 659.34
248 3,951.29 12,679.23 12,679.23
248.5 4,701.53 2,163.21 14,842.44
3.16
Temporary Pool
elev(ft) area (sf) volume (cf) 2 volume (cf)
240.5 44
242.5 782.34 826.34 826.34
248 4,647.29 14,931.48 15,757.82
248.5 5,551.53 2,549.71 18,307.53
249 6,751.65 3,075.80 21,383.32
250 7,768.92 7,260.29 28,643.61
252 9,971.11 17,740.03 46,383.64
252.2 14,146.68 2,411.78 48,795.42

Drawdown Times
Pond A
@ 246.75,4"orifice
Volume 59,308.00 3.5.2. Orifice Equation
The basic equation for orifices is:
Cd 0.60
diameter," 4.00 Q=CDA 2gHo
Axs,sf 0.0873
g,f/s^2 32.20 Where: Q = Discharge(cfs)
CD = Coefficient of discharge(dimensionless)-see Table 3-8
Ho,ft 0.53 A = Cross-sectional area of flow at the orifice entrance(sq ft)
g = Acceleration of gravity(32.2 ft/sec2)
Q,fps 0.305 Ho= Driving head(ft),measured from the centroid of the orifice area to
Drawdown Time,days 2.25 the water surface-Note:Usually use Ho/3 to compute
drawdown through an orifice to reflect the fact that head is
decreasing as the drawdown occurs.
pond B Ho considered as H/3.
@ 250.0,1.5"orifice
Table 3-8
Values of Coefficient of Discharge,Co(Malcom,1989)
Entrance Condition Co
Volume 10,336.00 Typical default value 0.60
Square-edged entrance 0.59
Cd 0.60 Concrete pipe,grooved end 0.65
Corrugated metal pipe,mitred to slope 0.52
diameter," 1.50 Corrugated metal pipe,projecting from fill 1.00
Axs,sf 0.0123
g,f/s^2 32.20
Stormwater Management and Calculations 3-13 July 2007
Ho,ft 0.48
Q,fps 0.041
Drawdown Time,days 2.92