20211213_ADI_Reply_Merritt_-_Response_to_Comments_68-04

DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485
SMITH GARDNER
ADDRESS TEL WEB
14 N. Boylan Avenue, Raleigh NC 27603 919.828.0577 www.smithgardnerinc.com
December 13, 2021
Mr. David D. Miller, P.E.
State Mining Specialist
Division of Energy, Mineral Land Resources
Department of Environmental Quality
1612 Mail Service Center
Raleigh, NC 27699-1612
RE: Merritt's Gravel Pit
Response to Comments 92 — Mine Application
Permit No. 68-04
Orange County, North Carolina
Dear David:
On behalf of Merritt's Gravel Pit, Inc., Smith Gardner, Inc. (S+G) is responding to comments
dated December 9, 2021 (copy attached) for the mine permit modification application (Permit
No. 68-04). Please find each comment in italics followed by current response or progress in
bold below.
1. The orientation of baffles within the sediment basins and channels DC-1, DC-2, and DC-3
must be such that flow into the basin passes through at least two baffles prior to
discharging through the skimmer outlet. As currently shown, short circuiting of the flow
to the outlet would occur.
Response
The entry points into the sediment basins for DC-1, DC-2, and DC-3 have been adjusted so
that short circuiting of flow no longer occurs. This update has been reflected in the
attached updated drawing set on sheets 3 and 4, drawings S2 and S3.
2. Provide schedule or plan notes indicating the type of temporary liner to be installed in the
temporary diversion ditches and permanent channels. It should be noted that the design
calculations indicate that all diversions and channels will be lined with "NA Green - Curlex
I or equal." Curlex is a product produced by American Excelsior Company not North
American Green, so some clarification is needed regarding the intended product
specification here...
Response
A note specifying the intended temporary liner has been added to details 4 and 5 on sheet
6, drawing EC1 on the attached updated drawing set. The drainage channel calculation
sheet has also been updated to reflect this specification and is attached.

DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485
Mr. David D. Miller, P.E.
December 13, 2021
Page 2of2
3. Vegetate the area of the buffer that lies on the northern permit boundary, between your
main haul road and the Carrboro Pond. Please supply the following when the job is
completed:
a. Photographic proof of the completed project.
b. The type and amount of supplements that were used.
c. The seed mix used.
d. The amount of seed used.
Response
Following the site visit by DEMLR on December 6, 2021, the site regraded the western
slope (understanding an incorrect directional reference above) and buffer in question,
fixing all the ruts and wash outs. The area was approximately 0.5 acres. 18 truckloads of
topsoil were hauled and placed from the mine site stockpile to slope adding an
approximate four (4) to five (5) inch lift across the buffer area. Approximately 250 lbs of
..pHast Cal" 'lime was applied followed by 500 lbs of 10-10-10 fertilizer. 150 lbs of a
contractors mix of 80/20 Tall Fescue and Rye was applied followed by straw that was
crimped by the dozer cleats utilizing approximately 60 bales. A photographic log is
attached for your review as requested.
Please contact us with comments of questions at 919-828-0577 or by email below.
Sincerely,
SMITH GARDNER, INC.
DocuSigned by:
E
�u C. U
CSECC95C937E4AC...
Jesse C. Li, E.I.
Staff Engineer, Ext. 170
iesse(asmithaardnerinc.com
App4411.� $ f
"R {1
SSION
s SEAL 's
Docusigned by: % = 12, 13/2021
3369FBA008BB445... i V��'.N(��µ�(.� j•��� �i�
Stacey A. Smith, P.E. •.,, �Y A. �.•`�
Senior Engineer, Ext. 127a'�°'"��''��,
stacev(asmithaardnerinc.com
sas/jcl
Att. DEQ Comments dated 12/9/2021
Updated Drainage Channel Calculation Sheet
Updated Drawing Set
Photographic Log
CC: Katelin Merritt, Merritt's Gravel Pit Kipp Liobl, ABI Equipment
Bill Denton, NC DEQ RRO Toby Vinson, NC DEMLR
Brian Wrenn, NC DEMLR
File
H:\Projects\Merritts Gravel Pit Mine\Permit Application\Response to Comments\RTC 2\Merritt - Response to Comments 12-13-21.docx

DocuSign Envelope ID: C6EBA72B-291B-4C5F-95C4-BA8A8020F485
ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
BRIAN WRENN
Director
Certified Mail
Return Receipt Requested
7016 2140 0000 4368 3827
Ms. Katelin Merritt
Merritt's Gravel Pit Inc.
3200 Damascus Church Road
Chapel Hill, NC 27516
RE: Tony Merritt's Gravel Pit Application
Mining Permit Number: 68-04
Orange County
Cape Fear River Basin
Dear Ms. Merritt:
NORTH CAROLINA
Environmental Quality
December 9, 2021
We have reviewed the modification request your company submitted for the referenced mine site. In order for this
office to complete its review of the referenced project in accordance with G.S. §74-50 and §74-5 l of the Mining
Act of 1971, please provide the additional or revised information in accordance with the following comments:
I. The orientation of baffles within the sediment basins and channels DC-1, DC-2, and DC-3 must be such
that flow into the basin passes through at least two baffles prior to discharging through the skimmer outlet. As
currently shown, short circuiting of the flow to the outlet would occur.
2. Provide schedule or plan notes indicating the type of temporary liner to be installed in the temporary
diversion ditches and permanent channels. It should be noted that the design calculations indicate that all diversions
and channels will be lined with "NA Green — Curlex I or equal." Curlex is a product produced by American
Excelsior Company not North American Green, so some clarification is needed regarding the intended product
specification here.
3. Vegetate the area of the buffer that lies on the northern permit boundary, between your main haul road and
the Carrboro Pond. Please supply the following when the job is completed:
a. Photographic proof of the completed project.
b. The type and the amount of supplements that were used.
C. The seed mix used.
d. The amount of seed used.
D ! ;:A. North
North Carolina Department of Environmental Qoallty I Division of Energy, Mineral and land Resources
512 North Salisbury Street 1 1612 Mail Service Center I Raleigh. North Carolina 27699-1612
H�rrr�aouHn s
\ /"� 919.707.9200

DocuSign Envelope ID: C6EBA72B-291B-4C5F-95C4-BA8A8020F485
Certified Mail
7016 2140 0000 4368 3827
To complete the processing of your application, please forward two (2) copies of the requested information to my
attention at the following address:
Division of Energy, Mineral and Land Resources
Department of Environmental Quality
1612 Mail Service Center
Raleigh, NC 27699-1612
As required by 15A NCAC 513.0113, you are hereby advised that you have 180 days from the date of your receipt
of this letter to submit all of the requested information. If you are unable to meet this deadline and wish to request
additional time, you must submit information, in writing, to the Director clearly indicating why the deadline cannot
be met and request that an extension of time be granted. If an extension of time is not granted, a decision will be
made to grant or deny the mining permit based upon the information currently in the Department's files at the end
of the 180-day period.
Though the preceding statement cites the maximum time limit for your response, we encourage you to provide the
additional information requested by this letter as soon as possible. Your prompt response will help us to complete
processing your application sooner.
Please contact me at [phone] if you have any questions.
Sincerely,
David Miller
State Mining Engineer
Enclosures:
cc: Mr. Bill Denton, PE, RRO

DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485
TEL
WEB
SMITH GARDNER
PROJECT Merritt's Gravel Pit
14 N. Boylan Avenue, Raleigh, NC27603 1 919.828.0577
SHEET 1 OF
SUBJECT Drainage Channel Analysis JOB # MERRITT-21-1
www.smithgardnerinc.com
6 DATE 12/ 7/ 2021
COMPUTED BY JCL
CHECKED BY SAS
OBJECTIVE: To design drainage channels, ditches, etc. to handle stormwater flow from the design storm(s). The main
design criteria will be to ensure that all drainage channels, ditches, etc. will be able to accommodate the
peak discharge from the design storm without overtopping and without exceeding the allowable shear
stress and/or velocity of the selected channel lining.
REFERENCES: Federal Highway Administration (2001), Urban Drainage Design Manual, Hydraulic Engineering Circular
No. 22, FHWA NHI-01-021, Second Ed., U.S. Dept. of Transportation, Washington, D.C.
North Carolina Division of Land Resources (2013 Updates), North Carolina Erosion & Sediment Control
Planning & Design Manual, Raleigh, NC.
Malcom, H. Rooney (1989 & 2003 Supplement), Elements of Urban Stormwater Design, NC State Univ.,
Raleigh, NC.
Pennsylvania DEP Bureau of Watershed Protection (2000), Erosion and Sediment Pollution Control
Program Manual.
ANALYSIS: The following approach is used in the design of drainage channels:
1 Determine the peak discharge from the design storm(s) (from HydroCAD or spreadsheet
methods). For permanent linings (Grass, TRM, rip rap, gabions, etc.) use the peak discharge
from the 25-Yr 24-Hr storm unless otherwise specified. For grass lined channels, a smaller
design storm (2-Yr 24-Hr -unless otherwise specified) is used to evaluate temporary linings.
2- Input other design parameters (bottom width; side slopes; minimum freeboard, min./max.
slopes; and channel lining).
3. Based on the design parameters calculate normal depth of flow, velocity, Froude number, and
maximum shear stress for both max./min. slopes. Also determine the critical slope and
corresponding normal depth.
4. Compare the velocity and/or shear stress to allowable values (the maximum slope val ues will
control). If val ues are exceeded, revise design parameters as required.
5. Based on normal depth values and required freeboard (generally use the greater of 6 inches or
25% of the flow depth), determine the minimum channel depth and top width for both max./min.
slopes (the minimum slope values will control).
6. If the channel has a significant curved reach, evaluate the shear stress and superelevation of
the water surface in the bend.
CALCULATIONS:
- Manning's Equation:
1.49AR2'3S"2 AV (HEC-22 Eq. 5-5)
Q= =
n
where: Q = discharge (cfs)
n = Manning's roughness coefficient (See Below)
A = cross sectional area of flow (ft2)
R = hydraulic radius (ft) = A/P
P = wetted perimeter
S = slope of channel (ft/ft)
V = average channel velocity (ft/sec)
SMITH GARNER, INC. DRAINAGE CHANNEL- Merritt - 12-7-21

DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485
PROJECT Merritt's Gravel Pit SHEET 2 OF 6 DATE 12/7/2021
COMPUTED BY JCL
SUBJECT Drainage Channel Analysis JOB # MERRITT-21-1 CHECKED BY SAS
- Maximum Shear Stress (Tractive Force Method
zd = ),d,S' (HEC-22 Eq. 5-13)
where: ro = maximum shear stress on channel lining (psf)
y = unit weight of water (62.4 pcf)
d = maximum depth of flow (ft)
S = channel slope(ft/ft)
- Froude Number:
v
Fr =
TTA
where: F,
= Froude number (dimensionless)
v
= flow velocity (ft/sec)
g
= acceleration of gravity (32.2 ft/sec`)
A
= cross -sectional area of flow (ft`)
T
= top width of flow (ft)
Note that A/T=the hydraul
is depth (D). For Fr > 1.0, flow is supercritical; Fr < 1.0, flow is subcritical; Fr = 1.0, flow is
critical.
Critical Slope:
The critical slope (Sj is the slope at which Fr = 1.0. When the slope is between 0.7S. and 1.3S. , unstable
flow may occur as small flow disturbances can initiate a change in the flow state. If slopes are within this
range, consider additional freeboard.
- Manning's Roughness Coefficient (nl:
Gr ass:
n = (HEC-22 Eq. 5-6- 5-10)
[K+ 19.971og(R1.4S0.4)]
where: R =
hydraulic radius (ft)
K =
vegetative coefficient (depending on retardance class)
= 15.8 (Class A)
= 23.0 (G ass B)
= 30.2 (G ass C)
= 34.6 (G ass D)
= 37.7 (G ass E)
S =
slope of channel (ft/ft)
Rip Rap:
1/6
n = Y
(PA DEP Manual Fig. 3)
21.6log ( d5 + 14
o
where: y =
depth of flow (ft)
050 =
median size of rip rap (ft)
SMITH GARDNER
SMITH GARNER, INC. DRAINAGE CHANNEL- Merritt - 12-7-21

DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485
PROJECT Merritt's Gravel Pit SHEET
SUBJECT Drainage Channel Analysis JOB #
Curved Channels (Where Applicable):
Shear Stress in Bend:
zh = Ka zd
where: r a =
Ka =
ra =
B =
Superelevation at Outside of Bend:
V2 T
A d = O.5
gR,.
3 OF 6
MERRITT-21-1
(HEC-22 Eq. 5-15)
bend shear stress (psf)
function of Rc/B (use HEC-22 Chart 21)
maximum shear stress on channel lining (psf)
radius to the centerline of the channel (ft)
bottom width of channel (ft)
(HEC-22 Eq. 5-11 modified)
DATE 12/ 7/ 2021
COMPUTED BY JCL
CHECKED BY SAS
where: A 0 = superelevation of water surface between the outer channel bank and the
centerline of the channel (avg. water surface before bend) (ft)
V = average channel velocity (ft/sec)
T = top width of flow (ft)
g = acceleration of gravity (32.2 ft/sec2)
A, = radius to the centerl ine of the channel (ft)
Allowable Shear Stress/Velocity:
Grass -Lined Channels:
For grass -lined channels, an allowable velocity approach is applicable for slopes flatter than 10%. For
slopes of 10% and steeper appropriate permanent linings should be used. For use in the evaluation of
curved channels, the following allowable shear stress values (lb/ftz) can be assumed based on retardance
cl ass:
Gass A: 3.7
Gass B: 2.1
G ass C: 1
Gass D: 0.6
G ass E: 0.35
Rip Rap -Lined Channels:
For rip rap -lined channels, an allowable velocity approach is applicable for slopes flatter than 10% (see table
below). For slopes of 10% or steeper, use the following equation:
zaz/,_ = 4 x dso (HEC-22 Eq. 5-17)
where: ra„ow = allowable shear stress (psf)
050 = median size of rip rap (ft)
SMITH GARDNER
SMITH GARNER, INC. DRAINAGE CHANNEL- Merritt - 12-7-21

DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485
PROJECT Merritt's Gravel Pit
SHEET 4 OF 6
SUBJECT Drainage Channel Analysis JOB #
MERRITT-21-1
DATE 12/ 7/ 2021
COMPUTED BY JCL
CHECKED BY SAS
Riprap Gradation, Filter Blanket Requirements, Maximum Velocities
NSA No.
Graded Rock Size in
Filter Blanket Re uiremell
Vmax
(ftlsec
Max.
deo*
Min.
Size NSA No.
Placement
Thickness
R-1
1.5
.75
No
FS-1
NIA
2.5
R-2
3
1.5
1
FS-1
NIA
4.5
R-3
6
3
2
FS-1
3
6.5
RA
12
6
3
FS-2
4
9.0
R-5
18
9
5
FS-2
6
11.5
R-6
24
12
7
FS-3
8
13.0
R-7
30
15
12
FS-3
10
14.5
The d5o stone size is the size exceeded by 50% of the total weight of the tonnage shipped (i.e. 50%
by weight shall consist of pieces larger than the d5o stone size").
** This is a general standard. Soil conditions at each site should be analyzed to determine actual filter
size. A suitable woven or non -woven geotextile underlayment, used according to manufacturer's
recommendations, may be substituted for the filter stone.
Ref • PA DEPManua) Table 5
Reno Mattress or Gabion- Lined Channels:
For Reno mattress or gabion-lined channels, use allowable velocityfor slopes flatter than 10%and
allowable shear stress for slopes of 10%or steeper (see table below).
Maximum Permissible Velocities for Reno Mattress & Gabions
Permissible —
Thickness
Rock Fill
Permissible*
Shear Stress
Type
InInches
Gradation in
Velocity (fps)
Iblfts
.025-.030
6
3-6
6.0
8.35
Reno
025 - .030
6 - 10
3-6
12.0
8.35
Mattress
025 - .030
10 - 12
3-6
15.0
8.35
.025-.030
12-18
4-6
18.0
8.35
Gabion
.027
-18
5-9
22.0
8.35
Permissible velocities may be increased by the introduction of sand mastic grout. Refer to
manufacturer's recommendations/specifications for permissible velocities and for recommendations
regarding filters or geotextile fabric underlayment when using Reno mattresses or gabions for
channel linings.
**Based on vegetation completely grown.
Ref. PA DEPManua/ Table 95
SMITH GARDNER
SMITH GARNER, INC. DRAINAGE CHANNEL- Merritt - 12-7-21

DocuSign Envelope ID: C6EBA72B-291B-4C5F-95C4-BA8A8020F485
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DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485
5+6 AGlNEERS
PHOTOGRAPHIC LOG
Client Name:
Site Location:
Project No.
Merritt's Gravel Pit
3200 Damascus Church
Road, Chapel Hill, NC
MERRITT-21-1
Photo No.
Date:
1
12/8/2021
Direction Taken:
View to the North
parallel to buffer.
Description:
Picture of regrading
along the buffer

DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485
S+G ENGINEERS PHOTOGRAPHIC LOG
Client Name:
Site Location:
Project No.
Merritt's Gravel Pit
3200 Damascus Church Road, Chapel Hill, NC
MERRITT-21-1
Photo No.
Date:
2
12/10/2021
Direction Taken:
View to the South
parallel to buffer.
Description:
Picture of regrading and
IL
placement of topsoil.
,
.
If.I rt
IT if I,
Y
t1il 1p

DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485

DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485
5+G AGlNEERS
Client Name:
Merritt's Gravel Pit
Photo No. Date:
4 12/11/2021
Direction Taken:
View to the North
parallel to buffer.
Description:
Picture of placement of
straw and dozer
crimping.
Site Location:
3200 Damascus Church Road, Chapel Hill, NC
I
PHOTOGRAPHIC LOG
Project No.
MERRITT-21-1

DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485
5+6 AGINEERS PHOTOGRAPHIC LOG
Client Name:
Site Location:
Project No.
Merritt's Gravel Pit
3200 Damascus Church Road, Chapel Hill, NC
MERRITT-21-1
Photo No.
Date:
q
5
12/11 /2021
Direction Taken:
View to the North
parallel to buffer.
�F��. r a
'Ni
Description:
Picture of finished slope.
i
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DocuSign Envelope ID: C6EBA72B-291 B-4C5F-95C4-BA8A8020F485
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