Merritts_Gravel_Pit_Response_to_Comments1_10-28-21

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
SMITH GARDNER
ADDRESS TEL WEB
14 N. Boylan Avenue, Raleigh NC 27603 919.828.0577 www.smithgardnerinc.com
October 28, 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 — 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 October 8, 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.
Please identify all streams, wetlands, and buffers (delineate between Zone 1 and Zone 2)
on the plan sheets. Identify the permitted impacts and impact areas on the erosion and
sedimentation control plan sheets to correspond with the USACE and DWR documents.
Include any additional measures, construction specifications, maintenance requirements
and construction sequencing as required by the 404/401/Buffer Determination and Buffer
Authorization on the plan sheets. Please supply copies of the 404/401/Buffer
Determination and Buffer Authorization.
Response
Zone 1 and zone 2 delineations for the stream buffer north of the site have been added to
the drawings. A site assessment was provided in Appendix F of the mine permit application
package.
No streams or wetlands under the jurisdiction of the Clean Water Act or State
Isolated/Non-federal waters rules were found within the proposed mine limits based on a
site review by Carolina Ecosystems, Inc. scientists. No permits or authorizations are
required under these rules for the proposed work.
As can be seen in the attached figures, five features are shown on or immediately adjacent
to the site on the NRCS soil survey, and therefore potentially buffered under the Jordan
Lake Rules. Each is addressed below:
• Feature 1 is shown on the USGS and NRCS mapping, but is off -site to the
north. Associated buffers may extend slightly onto the property as shown in the

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Mr. David D. Miller, P.E.
October 28, 2021
Page 2of7
plans. Grading and revegetating in the outer 20 feet (Zone 2) is considered Exempt
and does not require DEQ authorization as long as diffuse flow and the health of
existing vegetation in Zone 1 is not compromised. The proposed basin discharge
will control stormwater and maintain diffuse flow and health of vegetation in Zone
1 through rip rap dissipators designed to meet these criteria.
• Feature 2 is shown on NRCS mapping, but was not present on the ground. A buffer
determination is not required for this feature as it is within the mine limits and
would qualify for an "Exemption When Uses are Present and Ongoing". The mining
activity was present prior to the inception of the Jordan Buffer rules in 2009.
• Feature 3 is shown on NRCS mapping, but was not present on the ground. A buffer
determination is not required for this feature as it is within the mine limits and
would qualify for an "Exemption When Uses are Present and Ongoing". The mining
activity was present prior to the inception of the Jordan Buffer rules in 2009.
• Feature 4 is shown on NRCS mapping, but was not present on the ground. It may
be present on the property to the south, which was not inspected as it is off -
site. Activities within this feature's buffer were addressed via a mediated
settlement with the Town of Carrboro in March of 2021.
• Feature 5 is shown on NRCS mapping, but was not present on the ground. Since
this area is beyond the proposed mine limits and no activity proposed in the area, a
buffer determination is not required.
2. Provide delineations of watersheds flowing to each sediment basin at full scale (small
scale in report shows insufficient level of detail). Provide design for worst case during the
life of mine. Provide narrative explaining the design procedure for the basins. Simply
providing model inputs/results is insufficient. How was the pumping discharge from
dewatering operations factored into the design?
Response
An Erosion and Sedimentation Control Plan is attached. The plan provides a narrative
explaining design procedures for the sediment basins and the temporary diversions.
3. Provide calculations for the temporary diversions indicating they will be stable for 10-year
return period design storm. Provide additional liners to ensure they meet this standard. If
using detail 5 Sheet EC 1, toe of slope must be armored with rip rap to appropriate extents
where water flows.
Response
Calculations for the temporary diversions are provided in the appendix of the Erosion and
Sedimentation Control Plan. Detail 5 on Sheet EC1 has also been updated.

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Mr. David D. Miller, P.E.
October 28, 2021
Page 3of7
4. Provide 3 baffles on each sediment basin per design criteria specified in the NC Erosion
and Sediment Control Planning and Design Manual.
Response
Sheets S1, S2, and S3 have been updated to show 3 baffles on each sediment basin.
5. Provide additional measures to ensure water is discharged into the sediment basins in a
manner to prevent erosion. Provide a stable conveyance from diversions into basins (i.e.
rip rap lined channel, slope drain, tarp, etc.). Provide stable conveyance (extend pipe,
provide tarp or other acceptable practice) from outlet of skimmer to perimeter silt
fence/silt fence outlet. Provide construction details as needed for stable conveyance.
Response
Rip rap lined channels at the drainage channel discharge points into the sediment basins
have been added to the drawings.
6. Provide silt fence and silt fence outlet below the skimmer outlet for both basins.
Response
Silt fence and stone fence outlets have been added to the outlets of both sediment basins.
7. Specify the structure/device that will be used to dewater temporary basins prior to removal
and/or conversion to a permanent structure. Pumps and silt bags are typically used for
this purpose. Provide a plan detail, construction specifications, and maintenance
requirements for silt bags. Specify pumping rates compatible with silt bag size that is
selected. Construction detail should specify a floating intake located in the skimmer cell.
Include a symbol/icon on the legend for this structure. Detail the use of this device in the
construction sequence. Include the location of the sediment filter bag on the plan sheets.
Specify in the construction sequence that silt bag will be continuously monitored during
operation.
Response
A note about silt bags have been added to Sheet 3 Drawing S2 along with a silt bag detail
for Sheet 6 Drawing EC1.
8. Provide the location of the emergency spillway for the basins. Emergency spillways must
be located in natural ground to reduce the potential for failure of the embankment.
Response
Emergency spillway locations have been added to drawings S2 and S3.

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Mr. David D. Miller, P.E.
October 28, 2021
Page 4of7
9. Due to the addition of at least one additional stormwater outfall location, the NCG02
general permit must be revised as needed to address this change.
Response
The site has held a NPDES General Permit for some time and once a Certificate of
Coverage is issued, all revisions to outfalls are conducted through periodic and annual
updates of the Stormwater Pollution Prevention Plan including discharge monitoring and
sampling. Although, the second discharge has not been constructed, the Stormwater
Pollution Prevention Plan is being prepared to include both outfalls pending approval of
the permit application.
10. Sheet 2 Dwg S 1: Leader arrow indicates south property line is the southern edge of the 60-
ft right-of-way shared with the property owner to the south. My understanding is that the
property line is actually the centerline of this right-of-way. Please correct this sheet. Other
sheets appear to have it labeled correctly.
Response
The leader arrow has been corrected.
11. With regard to existing violations of the mine permit for disturbance of the buffer areas,
the permit cannot be modified until all cited issues have been resolved (Operating
Condition 98).
Response
Merritt's Gravel Pit has made significant progress on the restoration of the northwest
corner of the property that was excavated beyond the mine limits. As of October 22, 2021,
Merritt's plan to have this area filled and completed by mid -November.
12. Please provide more conspicuous indicators of the extent of the high wall barriers (both
fencing and "safety berms". The symbology for fence and safety berms should be reflected
in the legends on sheets where they appear.
Response
The high wall barriers have been updated with more conspicuous indictors on Sheet 2
Drawing S1 and the symbology for the safety berms has been added to the legend.

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Mr. David D. Miller, P.E.
October 28, 2021
Page 5of7
13. Plans seem to indicate that the location of the well serving the residence owned by Tony
Wayne Merritt (Orange Co. PIN: 9777560215) is outside of 500 feet of the pit. Please verify.
Response
Merritt's has confirmed the location of one (1) drinking water well within the specified
parcel. Its location has been added to Sheet 2 Drawing S1.
14. Provide labels or symbols to differentiate occupied dwellings from other structures. Add
symbol to legend as needed.
Response
Occupied dwellings have been labeled.
15. With reference to Item 1h from the previous ADI letter, I do not see the aboveground
storage tanks located on the plans. Will they be relocated to the covered storage shown on
Sheet 2 Dwg S I?
Response
Please refer to the response given for Question 12 on the Mining Permit Application form.
Petroleum storage will be under cover and over an existing concrete pad and foundation.
All fueling of equipment will be done through third party fueling services.
16. Sheet 3 Dwg S2: Sediment Basin 1 discharge pipe and outlet dissipator are installed
through the undisturbed buffer and beyond permit limits. This isn't allowed.
Response
The discharge pipes and outlet protections for both sediment basins have been relocated.
17. Sheet 3 Dwg S2: Locations of temporary diversions and the proposed safety berm are on
top of each other which is physically impossible. Provide construction detail with plan view
and cross-section to show how each of these structures will be located relative to the
other. It should be noted that the base width of the temporary diversion as shown in the
construction detail would be 10 feet and the base width of the safety berm as shown in the
detail would be 25 feet assuming a 6 ft height. Proximity to the proposed excavation limits
must able be taken into account.
Response
The proposed locations of the temporary diversions and safety berm are correct. The
presence of the temporary diversions and safety berm will not be concurrent through the
Life of the mine. The safety berm shall be in use through the life of the mine until mine

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Mr. David D. Miller, P.E.
October 28, 2021
Page 6of7
reclamation grades have been achieved, at which time temporary diversions shall be used
when necessary. Sheet 3 Dwg S2 has been updated to clarify this.
18. Specify proposed height of safety berm in detail on Sheet 8 Dwg EC3.
Response
Safety berm height has been added to the detail.
19. Design report/Mining Application Page 4, Section 6.0, Item C: Per the most recent DEMLR
inspection, the marking of the mine boundaries has mostly been accomplished, but some
additional markers were still needed. The permit cannot be modified until all cited issues
have been resolved.
Response
The owner has completed marking the mine boundaries. The mine markers have been
identified in the permit drawings showing approximate location and a general mine marker
detail.
20. Sheet 7 Dwg EC2, Detail 2 Sediment Basin Cross Section: the rigid extension of the pipe
from the riser to the flexible coupling requires additional structural support to prevent
excessive movement and potential damage. How will it be protected during basin clean
out?
Response
The original detail shows the flexible coupling and hose in the wrong location along the
skimmer. The flexible coupling and hose should be located much closer to the edge of the
riser. The new location has been updated in the drawing detail. This new location will allow
site maintenance personnel to move the skimmer structure out of the way when cleaning
out the basins.
21. Sheet 8 Dwg EC3, Seeding Schedule: Remove sericea lespedeza from the seeding mix and
replace with appropriate annual seed. Sericea lespedeza is a perennial which tends to
compete successfully with more desirable turfgrass species in certain growing conditions.
Please note that tall fescue will require repeat seeding, watering, and other maintenance
to ensure a stand adequate to restrain erosion. A warm season grass may be preferred
depending upon the desired maintenance input by the owner.
Response
Sericea lespedeza has been replaced with Bermuda grass on the seeding schedule.

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Mr. David D. Miller, P.E.
October 28, 2021
Page 7of7
Please contact us with comments of questions at 919-828-0577 or by email below.
Sincerely,
SMITH GARDNER, INC.
DocuSigned by:
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Jesse C. Li, E.I.
Staff Engineer, Ext. 170
jesselasmithgardnerinc.com
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EDocuSigned by:
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Stacey A. Smith, P.E. �'+,,ear A. 12021
Senior Engineer, Ext. 1274,8°"""'
staceyfasmithgardnerinc.com
sas/jcl
Att. DEQ Comments dated 10/8/2021
Carolina Ecosystems Memo
Erosion and Sedimentation Control Plan
Updated Drawing Set
CC: Katelin Merritt, Merritt's Gravel Pit
Bill Denton, NC DEQ RRO
Brian Wrenn, NC DEMLR
File
Kipp Liobl, ABI Equipment
Toby Vinson, NC DEMLR
H:\Projects\Merritts Gravel Pit Mine\Permit Application\Response to Comments\Merritt - Response to Comments 10-2l.docx

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ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
BRIAN WRENN
Director
Certified Mail
Return Receipt Requested
7016 2140 0000 4368 3773
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
October 8, 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 §74-51 of the Mining
Act of 1971, please provide the additional or revised information in accordance with the following comments:
1. Please identify all streams, wetlands, and buffers (delineate between Zone 1 and Zone 2) on the plan sheets.
Identify the permitted impacts and impact areas on the erosion and sedimentation control plan sheets to correspond
with the USACE and DWR documents. Include any additional measures, construction specifications, maintenance
requirements and construction sequencing as required by the 404/401/Buffer Determination and Buffer
Authorization on the plan sheets. Please supply copies of the 404/401/Buffer Determination and Buffer
Authorization.
2. Provide delineations of watersheds flowing to each sediment basin at full scale (small scale in report shows
insufficient level of detail). Provide design for worst case during the life of mine. Provide narrative explaining the
design procedure for the basins. Simply providing model inputs/results is insufficient. How was the pumping
discharge from dewatering operations factored into the design?
3. Provide calculations for the temporary diversions indicating they will be stable for 10-year return period
design storm. Provide additional liners to ensure they meet this design standard. If using detail 5 Sheet EC 1, toe of
slope must be armored with rip rap to appropriate extents where water flows.
Provide 3 baffles on each sediment basin per design criteria specified in the NC Erosion and Sediment
Control Planning and Design Manual.
5. Provide additional measures to ensure water is discharged into the sediment basins in a manner to prevent
erosion. Provide a stable conveyance from diversions into basins (i.e. rip rap lined channel, slope drain, tarp, etc.)
DE Q North Carolina Department of Environmental Quality I Division of Energy, Mineral and Land Resources
_ 512 North Salisbury Street 1 1612 Mail Service Center I Raleigh, North Carolina 27699-1612
NO�TF i_.F(k INA
919.707.9200

Certified Mail
7016 2140 0000 4368 3733
Provide stable conveyance (extend pipe, provide tarp or other acceptable practice) from outlet of skimmer to
perimeter silt fence/silt fence outlet. Provide construction details as needed for stable conveyance.
6. Provide silt fence and silt fence outlet below the skimmer outlet for both basins.
7. Specify the structure/device that will be sued to dewater temporary basins prior to removal and/or
conversion to a permanent structure. Pumps and silt bags are typically used for this purpose. Provide a plan detail,
construction specifications, and maintenance requirements for silt bags. Specify pumping rates compatible with silt
bag size that is selected. Construction detail should specify a floating intake located in the skimmer cell. Include
a symbol/icon on the legend for this structure. Detail the use of this device in the construction sequence. Include
the location of the sediment filter bag on the plan sheets. Specify in the construction sequence that silt bag will be
continuously monitored during operation.
8. Provide the location of emergency spillway for the basins. Emergency spillways must be located in natural
ground to reduce the potential for failure of the embankment.
9. Due to the addition of at least one additional stormwater outfall location, the NCO02 general permit must
be revised as needed to address this change.
10. Sheet 2 Dwg S L Leader arrow indicates south property line is the southern edge of the 60-ft right-of-way
shared with the property owner to the south. My understanding is that the property line is actually the centerline of
this right-of-way. Please correct this sheet. Other sheets appear to have it labeled correctly.
11. With regard to existing violations of the mine permit for disturbance of the buffer areas, the permit cannot
be modified until all cited issues have been resolved (Operating Condition 913).
12. Please provide more conspicuous indicators of the extent of the high wall barriers (both fencing and "safety
berms". The symbology for fence and safety berms should be reflected in the legends on sheets where they appear.
13. Plans seem to indicate that the location of the well serving the residence owned by Tony Wayne Merritt
(Orange Co. PIN: 9777560215) is outside of 500 feet of the pit. Please verify.
14. Provide labels or symbols to differentiate occupied dwelling from other structures. Add symbol to legend
as needed.
15. With reference to Item I from the previous ADI letter, I do not see the aboveground storage tanks located
on the plans. Will they be relocated to the covered storage shown on Sheet 2 Dwg Sl?
16. Sheet 3 Dwg S2: Sediment Basin 1 discharge pipe and outlet dissipator are installed through the undisturbed
buffer and beyond permit limits. This isn't allowed.
17. Sheet 3 Dwg S2: Locations of temporary diversions and the proposed safety berm are on top of each other
which is physically impossible. Provide construction detail with plan view and cross-section to show how each of
these structures will be located relative to the other. It should be noted that the base width of the temporary diversion
as shown in the construction detail would be 10 feet and the base width of the safety berm as shown in the detail
would be 25 feet assuming a 6 ft height. Proximity to the proposed excavation limits must also be taken into account.
18. Specify proposed height of safety berm in detail on Sheet 8 Dwg EC3.

Certified Mail
7016 2140 0000 4368 3733
19. Design report/Mining Application Page 4. Section 6.0, Item C: Per the most recent DEMLR inspection, the
marking of the mine boundaries has mostly been accomplished, but some additional markers were still needed. The
/ permit cannot be modified until all cited issues have been resolved.
20. Sheet 7 Dwg EC2, Detail 2 Sediment Basin Cross Section: the rigid extension of pipe from the riser to the
flexible coupling requires additional structural support to prevent excessive movement and potential damage. How
will it be protected during basin clean out?
21. Sheet 8 Dwg EC3, Seeding Schedule: Remove sericea lespedeza from the seeding mix and replace with
appropriate annual seed. Sericea lespedeza is a perennial which tends to compete successfully with more desirable
turfgrass species in certain growing conditions. Please note that tall fescue will require repeat seeding, watering,
and other maintenance to ensure a stand adequate to restrain erosion. A warm season grass may be preferred
depending upon the desired maintenance input by the owner. Please note, this office may request additional
information, not included in this letter. as the mining application review progresses. Be advised that our review
cannot be completed until all of the items listed above have been fully addressed.
In order 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 5B.01 13, 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

This page intentionally left blank.

(41 CAROLINA
ECOSYSTEMS
Mr. Stacey Smith, P.E.
Smith Gardner Inc.
14 North Boylan Ave
Raleigh, NC 27603
RE: Preliminary Site Review
Merritt's Gravel Pit
3200 Damascus Church Road, Chapel Hill NC
Dear Stacey;
3040 NC 42 West; Clayton NC 27520
PO Box 41; Lewisville, NC 27023
P:919-606-1065 - F:919-585-5570
August 20, 2021
As requested, Carolina Ecosystems, Inc. (CEI) has performed a preliminary review of the above -
referenced property (Site) for wetlands, streams, and riparian buffers potentially subject to Section
404 of the Clean Water Act (CWA) and/or the Jordan Lake Water Supply Watershed Buffer Rule
(JLBR). The following report summarizes the results of this evaluation. The Site is located at
3200 Damascus Church Road, Chapel Hill NC between Smith Level Road and University Lake.
The Site is within the Jordan Lake watershed (Hydrologic Unit Code 030300020606) within the
Cape Fear River Basin, and drains generally west to Morgan Creek/University Lake (NC Stream
Index 16-41.2-(1.5)).
Background Data & Document Review
Prior to the field inspection of the Site (Figure 1), background materials were reviewed, including:
- US Geological Survey (USGS) 1:24,000 maps (1978, 1982, 1998 and 2019)
- Natural Resources Conservation Service (NRCS) Orange County Soil Survey (1977 and
Web Soil Survey)
- Aerial photography (2017)
- US Fish and Wildlife Service National Wetland Inventory (NWI) mapping
- Town of Carrboro Mediated Settlement Agreement (March 2021)
Several features are mapped on the Site in the resources above:
- Feature 1 — USGS and NRCS mapped stream paralleling the northern boundary of the Site
(Figures 2 & 3)
- Feature 2 — NRCS mapped stream draining north to Feature 1 (Figure 3)
- Feature 3 — NRCS mapped stream draining north to a tributary of Feature 1 (Figure 3)
- Feature 4 — NRCS mapped stream along the southern boundary of the Site (Figure 3)
- NWI forested wetland mapped west of the Site (Figure 4)
- NWI open water areas mapped within the mine limits (Figure 4)

Mr. Stacey Smith, P.E. Page 2
Merritt's Gravel Pit — Preliminary Site Review
August 20, 2021
On -Site Review
The Site (Figure 1) was traversed on August 16, 2021 by a CEI Senior Scientist. Georeferenced
field maps were used, including USGS 1:24,000 quadrangle, NRCS soil survey map, and aerial
photography, to ensure that the Site was reviewed comprehensively and all features identified
above were inspected. Each location was traversed on foot, and areas exhibiting any potential for
jurisdiction, regardless of mapping, were also reviewed. The active mine pits clearly contained
within berms were not inspected due to safety considerations.
Potential stream channels were evaluated for jurisdiction under the CWA or JLBR, using
indicators of ordinary high water mark for the former and the NC Division of Water Resources
Stream Identification Method (Version 4.11) for the latter. Features without any evident channel
or indicators are shown as "No Channel Present" in Figure 3.
Potential wetlands were evaluated for jurisdiction under the CWA using indicators for three
wetland criteria (soils, vegetation, and hydrology) described in the US Army Corps of Engineers
(USACE) 1987 Wetland Delineation Manual and 2012 Eastern Mountain and Piedmont Regional
Supplement (Version 2). Cursory visual inspection of vegetation and hydrology were performed,
along with a representative soil plug evaluation.
Results
The following points summarize the results of the Site review:
1. Feature 1 is predominantly located off -site but does encroach onto the Site in several
locations (Figure 4). This channel has strong stream indicators and is likely to be under
the jurisdiction of the CWA, as well as the JLBR. The latter rule would require a 50-foot
riparian buffer from the top of bank, which is approximated on Figure 4 using Light
Detection and Ranging (LiDAR) data (NC Spatial Data Download 2015) to establish the
channel location and a 53-foot offset (to account for a channel width up to 6 feet).
2. Features 2 and 3 extending onto the property from the north, and Feature 5 mapped near
the western boundary, are not present on the ground (Figure 3). Therefore, these features
are not likely to be subject to the CWA or JLBR.
3. Feature 4 was not present on the property or evident to the south based on visual review
from the edge of the property (Figure 3). However, the drainage off -site was not traversed
during this Site visit. Based on review of the Mediation Agreement between the Town of
Carrboro and TIK LLC, the channel was at most considered ephemeral. Therefore, Feature
4 would not be considered under JLBR jurisdiction, as only intermittent and perennial
streams are subject to the State buffer rules. The Town implements its own local buffer
rules including ephemeral streams, which are addressed in the March 2021 Mediated
Settlement Agreement.
4. No significant potential wetlands were present on the south side of Feature 1 within the
Site boundary. Minor wetland areas may be present close to the stream channel, but
contained within the approximated buffer.

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tT1CAROLINA Feet Property Boundary Revised: Orange County, NC
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Soil Survey Map, Sheet 32 Revised:

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Erosion and Sedimentation Control Plan
Mining Permit No. 68-04
Chapel Hill, North Carolina
Prepared for:
Merritt's Gravel Pit, Inc.
Chapel Hill, North Carolina
October 2021
Prepared by:
SMITH GARDNER
14 N. Boylan Avenue, Raleigh NC 27603 1919.828.0577
4 PRINTED ON 1-1 RECYCLED 111-
0 2021 Smith Gardner, Inc.
This document is intended for the sole use of the client for which it was prepared and
for the purpose agreed upon by the client and Smith Gardner, Inc.

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DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Erosion and Sedimentation Control Plan
Mining Permit No. 68-04
Chapel Hill, North Carolina
Prepared for:
Merritt's Gravel Pit, Inc.
Chapel Hill, North Carolina
October 2021
SMITH GARDNER
14 N. Boylan Avenue, Raleigh NC 27603 1 919.828.0577
PRINTED ON 100% RECYCLED PAPER
O 2021 Smith Gardner, Inc.
This document is intended for the sole use of the client for which it was prepared and
for the purpose agreed upon by the client and Smith Gardner, Inc.

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DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Erosion and Sedimentation Control Plan
Mining Permit No. 68-04
Chapel Hill, North Carolina
Prepared For:
Merritt's Gravel Pit, Inc.
Chapel Hill, North Carolina
S+G Project No. MERRITT-21-1
IJDocuSigned by:
�u C. U
C5ECC95C937E4AC...
Jesse C. Li, E.I.
Staff Engineer
DocuSigned by:
Sf" a.
1 qr QFRA0n APPL
Stacey A. Smith, RE
Senior Engineer
October 2021
8/2021
$+o,ren ithwaw�•
SMITH GARDNER
14 N. Boylan Avenue, Raleigh NC 27603 1 919.826.0577

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Mining Permit No. 68-04
Chapel Hill, North Carolina
Erosion and Sedimentation Control Plan
Table of Contents
Paqe
1.0
NARRATIVE.....................................................................................................................1
1.1 Project Description......................................................................................................1
1.2 Site Location.................................................................................................................1
1.3 Contact Information.....................................................................................................1
1.3.1 Engineer...........................................................................................................1
1.3.2 Owner...............................................................................................................2
1.4 Existing Site Conditions...............................................................................................2
1.5 Adjacent Areas.............................................................................................................2
1.6 Site Soils Information..................................................................................................2
2.0
DESIGN GUIDELINES AND PROCEDURES.....................................................................3
3.0
RUNOFF CALCULATIONS...............................................................................................3
3.1 Highest Discharge into Basins....................................................................................3
3.2 Post -Mine Reclamation Conditions............................................................................4
4.0
EROSION AND SEDIMENTATION CONTROL MEASURES...............................................4
4.1 Sediment Basins..........................................................................................................4
4.2 Drainage Channels......................................................................................................5
4.3 Temporary Diversion Ditches.....................................................................................5
4.4 Culverts........................................................................................................................5
4.5 Silt Fence......................................................................................................................5
4.6 Vegetative Stabilization...............................................................................................5
5.0
SCHEDULE FOR IMPLEMENTATION..............................................................................6
6.0
INSPECTION AND MAINTENANCE.................................................................................6
Table of Contents (Continued)
TABLES
Table 1 Summary of Peak Discharge Amounts..........................................................7
FIGURES
Figure 1 USGS Map (Chapel Hill, NC and Farrington, NC Quadrangles)
APPENDICES
Appendix A Erosion and Sedimentation Control Calculations
Merritt's Gravel Pit (Permit No. 68-04) Erosion and Sedimentation Control Plan
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Merritt's Gravel Pit (Permit No. 68-04)
October2021
Erosion and Sedimentation Control Plan
Table of Contents Page ii

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1.0 NARRATIVE
1.1 Project Description
Merritt's Gravel Pit plans to improve an existing sediment basin and construct a new
sediment basin at their mine site as part of an updated mine excavation and mine
reclamation plan. This plan discusses the sediment basin design as well as other
erosion and sedimentation control measures used for this project.
1.2 Site Location
The attached USGS map (Chapel Hill and Farrington Quadrangles) shows the
approximate location of the site and the location of stormwater outfalls for this project.
Additional information is as follows:
1.3
Address:
3200 Damascus Church Rd
Chapel Hill, NC 27516
Coordinates
(Site Entrance):
Latitude: 35.88 degrees
Longitude: -79.09 degrees
River Basin:
Cape Fear
Receiving Streams)
(Stream Classification):
Unnamed Tributary to Morgan
Creek (University Lake) (NSW)
Contact Information
1.3.1 En ineer
For questions regarding this erosion and sedimentation control plan, please
contact the following:
Smith Gardner, Inc.
Attn.: Stacey A. Smith, P.E.
14 N. Boylan Ave.
Raleigh, NC 27603
Phone: [phone]
Fax: [phone]
Email: stacey(dsmithgardnerinc.com.
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1.3.2 Owner
The owner of the site and the person to contact should sediment control issues
arise during the land -disturbing activity is as follows:
Merritt's Gravel Pit, Inc.
Attn.: Katelin Merritt, Vice President
3200 Damascus Church Rd
Chapel Hill, North Carolina 27516
Phone: [phone]
1.4 Existing Site Conditions
The site is a currently operational mine with one (1) existing sediment basin located on
the west side of the permitted area. The southeastern part of the site is an active
excavation area and the northwestern part of the site is primarily inert debris and soil
fill.
1.5 Adjacent Areas
The site lies in between properties owned by Tony Merritt to the west and northeast.
Damascus Church Rd borders the mine site to the southeast, and residential properties
border the site to the north and south. An unnamed tributary to University Lake lies just
to the north of the site. The site will be accessed from Damascus Church Rd at the
southeast end of the site.
1.6 Site Soils Information
The native surficial soils in the watershed for sediment basin 1 are Appling sandy loam
(ApB) and Louisburg (Wateree) sandy loam (LoC and LoR The Appling sandy loam is in
hydrologic soil group B and the Louisburg soils are in hydrologic soil group A. The
HydroCAD input for the sediment basin 1 design will assume a hydrologic soil group of
"B" for the purposes of runoff calculations.
The native surficial soils in the watershed for the pump basin are Louisburg (Wateree)
sandy loams (LoC and LoR The Louisburg soils are in hydrologic soil group "A". The
HydroCAD input for the pump basin design will assume a hydrologic soil group of "A" for
the purposes of runoff calculations.
The soil survey map (USDA NRCS Soils Map) is attached for reference.
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2.0 DESIGN GUIDELINES AND PROCEDURES
The erosion and sediment control design for the landfill was conducted based on guidelines and
procedures as set forth in the following references:
A. HydroCAD Software Solutions, LLC (2006), HydroCAD Stormwater Modeling System
Owner's Manual - Version 8, Chocorua, NH.
B. Malcom, H. Rooney (1989 & 2003 Supplement), Elements of Urban Stormwater Design,
NC State Univ., Raleigh, NC.
C. North Carolina Division of Land Resources (2013 Update), North Carolina Erosion &
Sediment Control Planning & Design Manual, Raleigh, NC.
3.0 RUNOFF CALCULATIONS
All stormwater flow volumes were calculated using the HydroCAD computer program (utilizing
USDA-N RCS (SCS) methods) and/or the Rational Method based on the 10-year, 24-hour storm
event required by current North Carolina Sediment Control regulations. Rainfall quantities
and/or intensities used in the analyses were derived from an analysis of design storms for the
site. Drainage areas were determined using AutoCAD on topographic sheets of the project
area. For each drainage area, runoff curve numbers (SCS methods) and/or runoff coefficients
(Rational Method) were selected based on ground cover conditions. Times of concentration
were calculated by HydroCAD using SCS methods.
The peak discharge from the 10-year 24-hour storm event was evaluated for highest discharge
into the basin through the life of the mine and post -reclamation conditions as described below.
The peak discharges for each condition are summarized in Table 1.
3.1 Highest Discharge into Basins
The highest possible discharge into the basins were modeled in HydroCAD. For the
existing sediment basin (sediment basin 1), the highest possible discharge into the basin
is achieved post -reclamation of the mine. The drainage area discharging into sediment
basin 1 is approximately 18.1 acres which produces a runoff inflow of approximately 34.9
cfs. This design inflow results in an outlet discharge of 1.1 cfs.
For the pump basin, the highest possible discharge into the basin would be during mine
operations when the basin receives stormwater runoff and stormwater from the
dewatering pump. The drainage area discharging into the pump basin is approximately
0.8 acres and produces a runoff discharge of approximately 1.4 cfs. The dewatering
pump, a Godwin CD150S Dri-Prime, has a maximum flow rate of 6.2 cfs (approximately
2,300 GPM). Therefore, the designed total inflow to the pump basin is the sum of the
stormwater runoff and dewatering pump, which is 7.6 CFS. At this maximum inflow, the
outlet peak discharge is 7.1 cfs from the pump basin.
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3.2 Post -Mine Reclamation Conditions
Post -reclamation conditions were modeled in HydroCAD. The post -reclamation
condition for sediment basin 1 is the same as the condition described for the highest
possible discharge into the basin, which results in a peak discharge of 1.1 cfs.
For the pump basin, post -reclamation conditions increase its watershed area. The post -
reclamation drainage area for the pump basin is 4.7 acres. Dewatering operations are
also no longer necessary after post -reclamation grades have been achieved, so the
discharge into the pump basin shall only include stormwater runoff. The discharge into
the pump basin is approximately 1.2 cfs, and the basin outlet has a discharge rate of 0.04
cfs.
4.0 EROSION AND SEDIMENTATION CONTROL MEASURES
The following erosion and sedimentation control measures are to be constructed as part of the
proposed construction. Appendix A includes calculation spreadsheets and HydroCAD reports.
4.1 Sediment Basins
There are two long-term (Sediment Basin 1 and the pump basin) sediment basins which
will serve the site. Sediment Basin 1 is located on the west side of the mine. The pump
basin is to be located to the northwest side of the mine and will be used for dewatering
during mining operations. Once mine operations are completed and reclamation grades
are achieved, this pump basin will transition for permanent use. These basins, when
considering the site post- reclamation, were designed in accordance with E&SCP&DM
Section 6.61.
Sediment basins are subject to several design requirements. Each sediment basin must
have a basin volume of 1,800 ft3/acre of disturbed area and should have a surface area
(measured at crest of principal spillway (riser)) of 0.01 acres/cfs (based on the peak flow
from the 10-year storm). Each basin must include a riser/barrel principal spillway and
must have an emergency spillway (preferably a weir type spillway). The crest of the
emergency spillway is set one foot above the invert of the riser and the spillway must
pass the peak run off from the design storm event with one foot (min.) of freeboard to
the crest of berm. Each riser/barrel assembly must be provided with an anchor
displacing a buoyant weight of at least 1.1 times the weight of water displaced by the
riser. Each riser must also be provided with a method of dewatering the basin. In
addition to E&SCP&DM requirements, each sediment basin was designed to have an
adequate surface area to achieve an 80% settling efficiency of a 40-micron (silt size)
particle at the peak discharge from the design storm. Each sediment basin was
modeled with the HydroCAD computer program and a spreadsheet was used to verify
the design requirements.
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4.2 Drainage Channels
Drainage channel calculations were conducted using a reformulation of Manning's
Equation in a spreadsheet format. The calculations determine the normal depth of flow
based on the peak discharge from the design storm (from HydroCAD) and assumed
channel dimensions/slope(s). Both temporary and/or permanent channel linings were
chosen, as appropriate, based on the calculated velocity and/or shear stress. Temporary
channel linings (if specified) were designed based on the peak discharge from a 2-year
24-hour design storm.
4.3 Temporary Diversion Ditches
Temporary diversion ditches were designed using criteria and standard cross section of
E&SCP&DM Section 6.20. The capacity and need for lining of these ditches was checked
using the same procedures as described above for drainage channels. For the HydroCAD
model and calculation spreadsheets, the slope of the existing ground was assumed to be
10% going towards the diversion berm. The maximum drainage area for the temporary
diversion for this site was assumed to be 4 acres.
4.4 Culverts
There are several culverts which will be used at the site to convey flow beneath
roadways and embankments. Most culverts will be directed to one of the site sediment
basins. Culverts were designed either using HydroCAD or a spreadsheet based on an
analysis of inlet and outlet control under the influence of the design storm to determine
the maximum headwater elevation. Where required, culvert outlets were designed for
outlet stabilization based on criteria set forth in E&SCP&DM, Section 6.41. Culverts
draining disturbed areas, which are not routed to a sediment basin, were designed with
a stone filter berm placed around the inlet to trap sediment.
4.5 Silt Fence
Silt fencing design was based on criteria set forth in E&SCP&DM, Section 6.62 including
the limitation of 100 feet of fencing for each acre of drainage area.
4.6 Vegetative Stabilization
Vegetative stabilization will be in accordance with the seeding schedule on the project
drawings and/or in the project specifications.
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5.0 SCHEDULE FOR IMPLEMENTATION
Erosion and sedimentation control measures will be established prior to, or as soon as practical
thereafter, any land disturbance or construction activities may begin in that portion of the site
which drains to the erosion control measures. The following general schedule will be followed
for this project:
A. Flag the clearing limits and identify any tree protection areas.
B. Install temporary gravel construction entrance/exit.
C. Clear the vegetated portion of the site and install silt and stone filter fencing prior to
stripping/grubbing.
D. Only strip/grub areas required for installation of structures, berms, and drainage
channels. Other areas will be stripped/grubbed once the sediment basin is completed.
E. Install sediment basin outlet structure; outlet protection and/or channel, berm, and
emergency spillway.
F. Perform earthwork as required for construction.
G. Perform fine grading and establish permanent vegetation on completed areas.
H. After stabilization, remove silt and stone filter fencing and other temporary measures
and install permanent vegetation on the disturbed areas.
Soil stabilization will be achieved on any area of the site where land disturbing activities have
temporarily or permanently ceased according to the following schedule:
A. All perimeter dikes, swales, ditches, perimeter slopes, and all slopes steeper than 3
horizontal to 1 vertical (3HIV) will be provided temporary or permanent stabilization
with ground cover as soon as practicable but in any event within 7 calendar days from
the last land disturbing activity.
B. All other disturbed areas will be provided temporary or permanent stabilization with
ground cover as soon as practicable but in any event within 14 calendar days from the
Last land disturbing activity.
C. Basins, traps, channels, and diversions will be lined with anchored rolled erosion control
products or rip rap and/or vegetated upon construction.
D. Permanent ground cover for all disturbed areas will be established within 15 working
days or 90 calendar days (whichever is shorter) following completion of construction or
development.
6.0 INSPECTION AND MAINTENANCE
All erosion and sedimentation control measures will be inspected at least once every 7 calendar
days and within 24 hours after any storm event of greater than 0.5 inches of rain per 24-hour
period and appropriate maintenance conducted. A rain gauge will be maintained on the site and
a record of the rainfall amounts and dates will be kept.
During inspections, any stormwater discharges from the site will be observed for stormwater
discharge characteristics to evaluate the effectiveness of the erosion and sedimentation control
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measures incorporating Best Management Practices (BMPs). If visible sedimentation is leaving
the disturbed limits of the site, corrective action will be taken immediately to control the
discharge of sediments.
Maintenance activities will include, but not be limited to the following:
A. The removal and satisfactory disposal of trapped or deposited sediments from basins,
traps, barriers, filters, and/or drainage features/devices;
B. Replacement of filter fabrics used for silt fences upon loss of efficiency; and
C. Replacement of any other components which are damage or cannot serve the intended
use.
Table 1 Summary of Peak Discharge Amounts
Storm
Discharge Point
Peak Discharge (cfs)
Highest Possible
Post -Reclamation
10-Year 24-Hour
(Rainfall = 5.17
inches)
Sediment Basin 1
0.04
0.04
Pump Basin
7.14
0.23
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1. TOPOGRAPHY FROM U.S.G.S. 7.5 MIN. QUADRANGLES "CHAPEL 0 2000' 4000'
HILL, NC" DATED 2019 AND "FARRINGTON, NC" DATED 2019.
PREPARED FOR: PREPARED BY: NO LIC. NO. F-1370 [ENGINEERING]
SITE LOCATION MAP SO COA NO. C01488
MERRITT'S GRAVEL PIT SMITH+GARONERCHAPEL HILL, NC
14 N. Boylan Avenue, Raleigh NC 27603 1919.828.0577
1526 Richland St., Columbia SC 29201
C.T.J. I S.A.S. I AS SHOWN I Aug 2021 I MERRITT21-1 I 1 I MERRITT-A0006
© 2021 Smith Gardner, Inc.

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AppendixA
Erosion and Sedimentation Control
Calculations
Erosion and Sedimentation Control Plan
Merritt's Gravel Pit
Chapel Hill, North Carolina

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Erosion and Sedimentation Control Plan
Appendix A: Erosion and Sedimentation Control Calculations
Table of Contents
1.0 Drainage and E&S Control Calculations - Overview
2.0 Analysis of Design Storms
3.0 USDA Soil Survey Report
4.0 Drainage Area Figures
5.0 Godwin Pump Information
6.0 Stormwater Routing (HydroCAD output)*
• 2-Year 24-Hour Storm
• 10-Year 24-Hour Storm
• 25-Year 24-Hour Storm
7.0 Drainage Channel Analysis
• Drainage Channels: DC-1 — DC-3
• Temporary Diversions
8.0 Sedimentation Basin Analysis
• Sediment Basin No. 1
• Pump Basin
9.0 Outlet Protection Analysis
*The design of culverts is included in the HydroCAD output.
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TEL
WEB
SMITH GARDNER
PROJECT Merritt's Gravel Pit
14 N. Boylan Avenue, Raleigh, NC27603 1 919.828.0577
SHEET 1 OF
SUBJECT Drainage & E&SC Cal cs. -Overview JOB # MERRITT-21-1
www.smithgardnerinc.com
2 DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
OBJECTIVE: To design stormwater conveyance, detention, and erosion and sedimentation control measures to remove
and contain stormwater flow from the design storm. The design of these measures will be based on:
• Design storm information for the site;
• Peak discharge calculations using the Rational Method and/or USDA-NRCS (SCS) Methods; and
• Stormwater routinq using USDA- NRCS (SCS) or other methods.
REFERENCES: Debo, T.N., and Reese, A.J. (1995), Municipal Storm Water Management, Lewis Publishers, Boca Raton, FL.
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.
Georgia Soil and Water Conservation Commission (2000), Manual for Erosion and Sediment Control in
Georgia, Fifth Edition, Athens, GA.
HydroCAD Software Solutions, LLC (2006), HydroCAD Stormwater Modeling System Owner's Manual -
Version 8, Chocorua, NH.
Malcom, H. Rooney (1989 & 2003 Supplement), Elements of Urban Stormwater Design, NC State Univ.,
Raleigh, NC.
North Carolina Division of Land Resources (2013 Updates), North Carolina Erosion & Sediment Control
Planning & Design Manual, Raleigh, NC.
North Carolina Division of Water Quality (July 2005) Updated Draft Manual of Stormwater Best
Management Practices, (Public Comment Version), Raleigh, NC.
Pennsylvania DEP Bureau of Watershed Protection (2000), Erosion and Sediment Pollution Control
Program Manual.
USDA-NRCS(1992), Computer Program for Project Formulation Hydrology(TR-20).
USDA-NRCS(1986 & 1999 Update), Urban Hydrologyfor Small Watersheds (TR-55).
Virginia Department of Conservation and Recreation (1992), Virginia Erosion & Sediment Control
Handbook. Third Edition. Richmond. VA.
ANALYSIS: The main design criteria will be to ensure that all stormwater conveyance and detention measures will be
able to accommodate the runoff from the design storm. Drainage channels, culverts, etc. were designed
based on the peak discharge to each measure. Detention measures were designed based on stormwater
routing methods and/or State/local criteria.
CALCULATIONS:
- Peak Discharge Calculations:
USDA- NRCS (SCS) Methods:
Use HydroCAD program to determine the peak discharge to each device or structure. HydroCAD is based
on the SCS unit hydrograph procedure, which is a principal component of NRCS TR-20. Alternatively
spreadsheets can be used to determine flow rates using the procedures detailed in NRCSTR-55.
SMITH GARDNER,INC. D&E&SCOVERMEWSG

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's Gravel Pit SHEET 2 OF 2 DATE 10/25/2021
COMPUTED BY JCL
SUBJECT Drainage & E&SC Cal cs. -Overview JOB # MERRITT-21-1 CHECKED BY SAS
Rational Method:
Q=CIA (Malcom Eq. I -1)
where: G = peak discharge (cfs)
G = rational runoff coefficient
I = applicable rainfall intensity (in/hr) of storm event (based on time of concentration)
A = drainage area (acres)
Time of Concentration:
The time of concentration for use in determining the peak discharge in the NRCS and/or Rational methods
can be determined bythe methods detailed in NRCSTR-55 or other methods. HydroCAD uses the NRCS
methods.
- Stormwater Routina:
Stormwater routing was accomplished using the HydroCAD program, which is based on USDA-NRCS (SCS) methods.
Unless otherwise specified, the unit hydrograph method was used. The storm type (i.e. Type 124-hr., Type II 24-hr.,
etc.) was selected as appropriate for the project location.
SMITH GARDNER
SMITH GARDNER,INC. D&E&SCOVERMEWSG

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
ADDRESS TEL WEB
SMITH F G A R D N E R 14 N. Boylan Avenue, Raleiqh, NC 27603 919.828.0577 www.smithgardnerinc.com
PROJECT Merritt's Gravel Pit SHEET 1 OF 2 DATE 10/25/2021
COMPUTED BY JCL
SUBJECT Analysis of Design Storms JOB # MERRITT-21-1 CHECKED BY SAS
OBJECTIVE: To compile the expected design storm depths and intensities over various return periods. These design
storm values will be used in various calculations.
REFERENCES: Rainfall data was obtained from thefollowingreferences:
Frederick, R.H., V.A. Myers, and E.P. Anciello (1977), "Five to 60-Minute Precipitation Frequencyfor the
Eastern and Central United States," NOAATechnical Memo. NWS HYDR&35, National Weather Service,
NOAA, U.S. Dept. Of Commerce, Silver Spring, MD.
U.S. Weather Bureau (1961), "Rainfall Frequency Atlas of the United States for Durations from 30 Minutes
to 24 Hours and Return Periods from 1 to 100 Years," U.S. Weather Bureau Technical Paper 40.
SMITH GARDNER, INC. DESIGN STORMS SG

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's Gravel Pit
SHEET
2/2
JOB#
MERPJTT-21-1
SUBJECT Analysis of Design Storms
DATE
10/25/2021
COMPUTED BY
JCL
CHECKED BY
SAS
LOCATION: Chapel Hill, NC
RETURN PERIOD
2-YR P
100-YR P
SOURCE
DURATION
(in)
(in)
5min
0.49
0.76
NOAAHYDRO.35
15 min
0.98
1.52
NOAA HYDR035
60 min
1.69
3.21
NOAAHYDRO.35
2 hr to 24 hr Rainfall Events =
USER INPUT
USWB TP-40
DEPTH -DURATION -FREQUENCY TABLE:
RETURN PERIOD
2-YR
5-YR
10-YR
25-YR
50-YR
100-YR
DURATION
(in)
(in)
(in)
(in)
(in)
(in)
5 min
0.49
0.54
0.58
0.65
0.70
0.76
10 min
0.78
0.86
0.93
1.03
1.12
1.21
15 min
0.98
1.08
1.17
1.30
1.41
1.52
30 min
1.33
1.55
1.71
1.96
2.15
2.35
60 min
1.69
2.03
2.28
2.64
2.93
3.21
2 hr
2.03
2.50
2.87
3.33
3.70
4.05
3 hr
2.16
2.67
3.09
3.61
4.04
4.46
6 hr
2.59
3.20
3.71
4.38
4.92
5.47
12 hr
3.06
3.81
4.44
5.28
5.98
6.70
24 hr
3.57
4.47
5.17
6.11
6.86
7.63
I NTENSITY- DURATION- FREQUENCY TABLE:
RETURN PERIOD
2-YR
5-YR
10-YR
25-YR
50-YR
100-YR
DURATION
(in/hr)
(in/hr)
(in/hr)
(in/hr)
(in/hr)
(in/hr)
5 min
5.83
6.46
6.98
7.79
8.45
9.10
10 min
4.65
5.15
5.56
6.21
6.73
7.25
15 min
3.90
4.32
4.67
5.21
5.65
6.08
30 min
2.65
3.09
3.42
3.92
4.31
4.70
60 min
1.69
2.03
2.28
2.64
2.93
3.21
2 hr
1.02
1.25
1.44
1.67
1.85
2.03
3 hr
0.72
0.89
1.03
1.20
1.35
1.49
6 hr
0.43
0.53
0.62
0.73
0.82
0.91
12 hr
0.26
0.32
0.37
0.44
0.50
0.56
24 hr
0.15
0.19
0.22
0.25
0.29
0.32
SMITH+GARDNER
SMITH GARDNER, INC. DESIGN STORMS SO

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
USDA United States
Department of
Agriculture
N RCS
Natural
Resources
Conservation
Service
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
Orange County,
North Carolina
Merritt's Gravel Pit
August 11, 2021

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nres.usda.gov/wps/
portal/nres/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nres) or your NRCS State Soil
Scientist (http://www.nres.usda.gov/wps/portal/nres/detail/soils/contactus/?
cid=nres142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
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DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at [phone] (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call [phone] (voice) or [phone] (TDD). USDA is an equal opportunity
provider and employer.
3

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Contents
Preface....................................................................................................................
2
How Soil Surveys Are Made..................................................................................5
SoilMap..................................................................................................................
8
SoilMap................................................................................................................9
Legend................................................................................................................10
MapUnit Legend................................................................................................
11
MapUnit Descriptions.........................................................................................11
Orange County, North Carolina.......................................................................13
ApB—Appling sandy loam, 2 to 6 percent slopes .......................................
13
ApC—Appling sandy loam, 6 to 10 percent slopes.....................................14
LoC—Louisburg (Wateree) sandy loam, 6 to 15 percent slopes.................15
LoF—Louisburg (Wateree) sandy loam, 15 to 45 percent slopes ...............
17
Pt —Pits, quarry ...........................................................................................
18
References............................................................................................................
20
4

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil -vegetation -landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Custom Soil Resource Report
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil -landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil -landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field -observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
0

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Custom Soil Resource Report
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
7

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
0

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
N
672220 672310 672400
35° 536" N
_o
M
c�+
Custom Soil Resource Report
Soil Map
672490 672580 672670
35° 52' 48" N
672220 672310 672400 672490 672580
3
N
Map Scale: 1:4,080 if printed on A landscape (11" x 8.5") sheet.
g N Meters
0 50 100 200 00
Feet
0 150 300 600 900
Map projection: Web Mercator Comer coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
9
672760 672850 672940
I I 1 1
672670 672760 672850 672940
V
673030
I35° 53' 6" N
3
i—
a 'rn
m 35° 52' 48" N
673030
3
v

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
MAP LEGEND
Area of Interest (AOI)
0
Area of Interest (AOI)
Soils
0
Soil Map Unit Polygons
im 0
Soil Map Unit Lines
■
Soil Map Unit Points
Special
Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
.4
Gravelly Spot
0
Landfill
Lava Flow
Marsh or swamp
+
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
oa
Sodic Spot
Custom Soil Resource Report
MAP INFORMATION
A
Spoil Area
The soil surveys that comprise your AOI were mapped at
1:20,000.
Stony Spot
Very Stony Spot
Warning: Soil Map may not be valid at this scale.
Wet Spot
Enlargement of maps beyond the scale of mapping can cause
Other
misunderstanding of the detail of mapping and accuracy of soil
.-
Special Line Features
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
Water Features
scale.
-
Streams and Canals
Transportation
Please rely on the bar scale on each map sheet for map
�}}
Rails
measurements.
Interstate Highways
Source of Map: Natural Resources Conservation Service
US Routes
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Major Roads
Local Roads
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
Background
distance and area. A projection that preserves area, such as the
Aerial Photography
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Orange County, North Carolina
Survey Area Data: Version 20, Jun 3, 2020
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jun 15, 2015—Oct
19, 2019
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
10

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Custom Soil Resource Report
Map Unit Legend
Map Unit Symbol
Map Unit Name
Acres in AOI
Percent of AOI
ApB
ApC
Appling sandy loam, 2 to 6
percent slopes
8.0
0.2
14.0%
0.3%
Appling sandy loam, 6 to 10
percent slopes
LoC
Louisburg (Wateree) sandy
loam, 6 to 15 percent slopes
20.0
35.3%
LoF
Louisburg (Wateree) sandy
loam, 15 to 45 percent slopes
25.1
44.1 %
Pt
Pits, quarry
3.5
6.2%
Totals for Area of Interest
56.8
100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
11

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Custom Soil Resource Report
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha -Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example.
12

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Custom Soil Resource Report
Orange County, North Carolina
ApB—Appling sandy loam, 2 to 6 percent slopes
Map Unit Setting
National map unit symbol: 2vy6t
Elevation: 70 to 1,310 feet
Mean annual precipitation: 39 to 47 inches
Mean annual air temperature: 55 to 63 degrees F
Frost -free period: 200 to 250 days
Farmland classification: All areas are prime farmland
Map Unit Composition
Appling and similar soils: 92 percent
Minor components: 8 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Appling
Setting
Landform: Interfluves
Landform position (two-dimensional): Summit, shoulder
Landform position (three-dimensional): Interfluve
Down -slope shape: Convex
Across -slope shape: Convex
Parent material: Residuum weathered from igneous and metamorphic rock
Typical profile
Ap - 0 to 6 inches: sandy loam
BE - 6 to 10 inches: sandy loam
Bt - 10 to 39 inches: clay
BC - 39 to 46 inches: sandy clay loam
C - 46 to 80 inches: sandy clay loam
Properties and qualities
Slope: 2 to 6 percent
Depth to restrictive feature: More than 80 inches
Drainage class: Well drained
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high
(0.57 to 1.98 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water capacity: Moderate (about 7.9 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 2e
Hydrologic Soil Group: B
Hydric soil rating: No
Minor Components
Helena
Percent of map unit: 8 percent
Landform: Interfluves
13

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Custom Soil Resource Report
Landform position (two-dimensional): Summit, shoulder
Landform position (three-dimensional): Interfluve
Down -slope shape: Convex
Across -slope shape: Convex
Hydric soil rating: No
ApC—Appling sandy loam, 6 to 10 percent slopes
Map Unit Setting
National map unit symbol: 3tgc
Elevation: 200 to 1,400 feet
Mean annual precipitation: 37 to 60 inches
Mean annual air temperature: 59 to 66 degrees F
Frost -free period: 200 to 240 days
Farmland classification: Farmland of statewide importance
Map Unit Composition
Appling and similar soils: 90 percent
Minor components: 2 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Appling
Setting
Landform: Hillslopes on ridges
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Linear
Across -slope shape: Convex
Parent material: Saprolite derived from granite and gneiss and/or schist
Typical profile
Ap - 0 to 6 inches: sandy loam
Bt1 - 6 to 18 inches: sandy clay loam
Bt2 - 18 to 36 inches: clay
BC - 36 to 52 inches: sandy clay loam
C - 52 to 80 inches: sandy loam
Properties and qualities
Slope: 6 to 10 percent
Depth to restrictive feature: More than 80 inches
Drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat)
(0.57 to 1.98 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water capacity: Moderate (about 8.5 inches)
Moderately high to high
14

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Custom Soil Resource Report
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: B
Hydric soil rating: No
Minor Components
Helena
Percent of map unit: 1 percent
Landform: Hillslopes on ridges
Landform position (two-dimensional): Shoulder, backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Concave
Across -slope shape: Convex, concave
Hydric soil rating: No
Vance
Percent of map unit: 1 percent
Landform: Hillslopes on ridges
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Linear
Across -slope shape: Convex
Hydric soil rating: No
LoC—Louisburg (Wateree) sandy loam, 6 to 15 percent slopes
Map Unit Setting
National map unit symbol: 3tr3
Elevation: 200 to 1,400 feet
Mean annual precipitation: 37 to 60 inches
Mean annual air temperature: 59 to 66 degrees F
Frost -free period: 200 to 240 days
Farmland classification: Not prime farmland
Map Unit Composition
Wateree and similar soils: 70 percent
Minor components: 30 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Wateree
Setting
Landform: Hillslopes on ridges
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Linear
Across -slope shape: Convex
Parent material: Saprolite derived from granite and/or gneiss
15

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Custom Soil Resource Report
Typical profile
A - 0 to 11 inches: loamy coarse sand
Bw - 11 to 22 inches: sandy loam
Cr - 22 to 50 inches: weathered bedrock
R - 50 to 80 inches: unweathered bedrock
Properties and qualities
Slope: 8 to 15 percent
Depth to restrictive feature: 20 to 40 inches to paralithic bedrock; 40 to 60 inches
to lithic bedrock
Drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Very low to low (0.00 to
0.01 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water capacity. Very low (about 1.8 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 6e
Hydrologic Soil Group: A
Hydric soil rating: No
Minor Components
Louisburg
Percent of map unit: 12 percent
Landform: Hillslopes on ridges
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Linear
Across -slope shape: Convex
Hydric soil rating: No
Ashlar
Percent of map unit: 7 percent
Landform: Hillslopes on ridges
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Linear
Across -slope shape: Convex
Hydric soil rating: No
Wake
Percent of map unit: 5 percent
Landform: Hillslopes on ridges
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Linear
Across -slope shape: Convex
Hydric soil rating: No
Wedowee
Percent of map unit: 5 percent
Landform: Hillslopes on ridges
16

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Custom Soil Resource Report
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Linear
Across -slope shape: Convex
Hydric soil rating: No
Rock outcrop
Percent of map unit: 1 percent
Hydric soil rating: No
LoF—Louisburg (Wateree) sandy loam, 15 to 45 percent slopes
Map Unit Setting
National map unit symbol: 3tr4
Elevation: 200 to 1,400 feet
Mean annual precipitation: 37 to 60 inches
Mean annual air temperature: 59 to 66 degrees F
Frost -free period: 200 to 240 days
Farmland classification: Not prime farmland
Map Unit Composition
Wateree and similar soils: 70 percent
Minor components: 30 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Wateree
Setting
Landform: Hillslopes on ridges
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Linear
Across -slope shape: Convex
Parent material: Saprolite derived from granite and/or gneiss
Typical profile
A - 0 to 11 inches: loamy coarse sand
Bw - 11 to 22 inches: sandy loam
Cr - 22 to 50 inches: weathered bedrock
R - 50 to 80 inches: unweathered bedrock
Properties and qualities
Slope: 15 to 40 percent
Depth to restrictive feature: 20 to 40 inches to paralithic bedrock; 40 to 60 inches
to lithic bedrock
Drainage class: Well drained
Runoff class: High
Capacity of the most limiting layer to transmit water (Ksat): Very low to low (0.00 to
0.01 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
17

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Custom Soil Resource Report
Frequency of ponding: None
Available water capacity: Very low (about 1.8 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 7e
Hydrologic Soil Group: A
Hydric soil rating: No
Minor Components
Ashlar
Percent of map unit: 15 percent
Landform: Hillslopes on ridges
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Linear
Across -slope shape: Convex
Hydric soil rating: No
Wedowee
Percent of map unit: 10 percent
Landform: Hillslopes on ridges
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Linear
Across -slope shape: Convex
Hydric soil rating: No
Wake
Percent of map unit: 4 percent
Landform: Hillslopes on ridges
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down -slope shape: Linear
Across -slope shape: Convex
Hydric soil rating: No
Rock outcrop
Percent of map unit: 1 percent
Hydric soil rating: No
Pt —Pits, quarry
Map Unit Setting
National map unit symbol: 3tr6
Elevation: 200 to 1,400 feet
Mean annual precipitation: 37 to 60 inches
Mean annual air temperature: 50 to 66 degrees F
Frost -free period: 145 to 240 days
Farmland classification: Not prime farmland
18

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Custom Soil Resource Report
Map Unit Composition
Pits, quarry. 95 percent
Minor components: 5 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Pits, Quarry
Setting
Parent material: Residuum weathered from granite and gneiss
Typical profile
R - 0 to 80 inches: bedrock
Properties and qualities
Slope: 0 to 700 percent
Depth to restrictive feature: 0 inches to lithic bedrock
Capacity of the most limiting layer to transmit water (Ksat): Very low to low (0.00 to
0.01 in/hr)
Available water capacity. Very low (about 0.0 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 8s
Hydric soil rating: No
Minor Components
Udorthents
Percent of map unit: 5 percent
Down -slope shape: Convex
Across -slope shape: Convex
Hydric soil rating: No
19

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
References
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of sampling
and testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-00.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
wetlands and deep -water habitats of the United States. U.S. Fish and Wildlife
Service FWS/OBS-79/31.
Federal Register. July 13, 1994. Changes in hydric soils of the United States.
Federal Register. September 18, 2002. Hydric soils of the United States.
Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric
soils in the United States.
National Research Council. 1995. Wetlands: Characteristics and boundaries.
Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.
U.S. Department of Agriculture Handbook 18. http://www.nres.usda.gov/wps/portal/
nres/detail/national/soils/?cid=nres 142p2_054262
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for
making and interpreting soil surveys. 2nd edition. Natural Resources Conservation
Service, U.S. Department of Agriculture Handbook 436. http://
www.nres.usda.gov/wps/portal/nres/detail/national/soils/?cid=nres142p2_053577
Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http://
www. nres.usda.gov/wps/portal/nres/detail/national/soils/?cid=nres142p2_053580
Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section.
United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of
Engineers wetlands delineation manual. Waterways Experiment Station Technical
Report Y-87-1.
United States Department of Agriculture, Natural Resources Conservation Service.
National forestry manual. http://www.nres.usda.gov/wps/portal/nres/detail/soils/
home/?cid=nres142p2_053374
United States Department of Agriculture, Natural Resources Conservation Service.
National range and pasture handbook. http://www.nres.usda.gov/wps/portal/nres/
detail/national/landuse/rangepasture/?cid=stelprdb1043084
20

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Custom Soil Resource Report
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430-VI. http://www.nres.usda.gov/wps/portal/
nres/detail/soils/scientists/?cid=nres142p2_054242
United States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States,
the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook
296. http://www.nres.usda.gov/wps/portal/nres/detail/national/soils/?
cid=nres142p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210. http://
www.nrcs.usda.gov/lnternet/FSE—DOCUMENTS/nrcsl 42p2_052290.pdf
21

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
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DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
This page intentionally left blank.

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
DA-2
2S
Sediment Basin 1
Sediment Basin Area DC-1 a- DA-1
SUbCa Reach and Link Drainage Diagram for Merrits Gravel Pit - Basin
Prepared by {enter your company name here} 10/28/2021
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin
Prepared by {enter your company name here} Page 2
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Area Listing (selected nodes)
Area (acres) CN Description (subcats)
21.900 61 >75% Grass cover, Good, HSG B (DA-1,DA-2)
0.450 98 Paved parking & roofs (2S)
22.350

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 3
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 2S: Sediment Basin Area Runoff Area=0.450 ac Runoff Depth>3.08"
Tc=0.0 min CN=98 Runoff=2.56 cfs 0.116 of
Subcatchment DA-1: Runoff Area=15.300 ac Runoff Depth>0.52"
Flow Length=1,010' Tc=17.7 min CN=61 Runoff=8.30 cfs 0.666 of
Subcatchment DA-2: Runoff Area=6.600 ac Runoff Depth>0.52"
Flow Length=1,670' Tc=18.0 min CN=61 Runoff=3.54 cfs 0.287 of
Reach DC-1: Avg. Depth=0.47' Max Vet=5.18 fps Inflow=8.30 cfs 0.666 of
n=0.035 L=500.0' S=0.0680 '/' Capacity=187.87 cfs Outflow=8.05 cfs 0.664 of
Reach DC-2: Avg. Depth=0.30' Max Vet=4.12 fps Inflow=3.54 cfs 0.287 of
n=0.035 L=200.0' S=0.0700 '/' Capacity=190.62 cfs Outflow=3.49 cfs 0.287 of
Pond SB-1: Sediment Basin 1 Peak Elev=401.18' Storage=39,036 cf Inflow=11.74 cfs 1.066 of
Primary=0.23 cfs 0.169 of Secondary=0.00 cfs 0.000 of Outflow=0.23 cfs 0.169 of
Total Runoff Area = 22.350 ac Runoff Volume = 1.069 of Average Runoff Depth = 0.57"
97.99% Pervious Area = 21.900 ac 2.01 % Impervious Area = 0.450 ac

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 4
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 2S: Sediment Basin Area
[46] Hint: Tc=O (Instant runoff peak depends on dt)
Runoff = 2.56 cfs @ 11.89 hrs, Volume= 0.116 af, Depth> 3.08"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 2 YR 24 HR Rainfall=3.57"
Area (ac) CN Descriotion
0.450 98 Paved parking & roofs
0.450 Impervious Area
Subcatchment 2S: Sediment Basin Area
Hydrograph
', ❑Runoff
2.56 cfs
Type 11 24-h r 2 YR 24 HR
Rainfall=3.57"
2 Runoff Area=0.450 ac
Runoff Volume=0.116 of
Runoff Depth>3.08"
LL Tc=0.0 min
1 CN=98
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 5
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-1:
Runoff = 8.30 cfs @ 12.14 hrs, Volume= 0.666 af, Depth> 0.52"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 2 YR 24 HR Rainfall=3.57"
Area (ac) CN Description
15.300 61 >75% Grass cover, Good, HSG B
15.300 Pervious Area
Tc Length
Slope
Velocity Capacity
Description
(min) (feet)
(ft/ft)
(ft/sec) (cfs)
11.7 300
0.1000
0.43
Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
6.0 710
0.0800
1.98
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fDs
17.7 1,010 Total
Subcatchment DA-1:
Hydrograph
9
■ Runoff
8.30 cfs
Type -Il -
2� _HR_ , -hr 2',
a YR
--- ---Rainfall-3. 57"--
7
Runoff -Area=15.300_ac-
6 RunoffVolume=0.666of
5 -, not De''pth>0.52..
LL ,, Flow Dength- 1,0 10
4
76`11,7-rein- -
3
---CH=:61-
2
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 6
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-2:
Runoff = 3.54 cfs @ 12.14 hrs, Volume= 0.287 af, Depth> 0.52"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 2 YR 24 HR Rainfall=3.57"
Area (ac) CN Description
6.600 61 >75% Grass cover, Good, HSG B
6.600 Pervious Area
Tc
Length
Slope
Velocity Capacity
Description
(min)
(feet)
(ft/ft)
(ft/sec) (cfs)
7.3
210
0.1600
0.48
Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
10.7
1,460
0.0230
2.27
Shallow Concentrated Flow,
Grassed Waterwav Kv= 15.0 fos
18.0 1,670 Total
Subcatchment DA-2:
Hydrograph
❑ Runoff
3.54 cfs
Type 11 24-h r 2 YR 24 HR
Rainfall=3.57"
3
Runoff Area=6.600 ac
Runoff Volume=0.287 of
2
Runoff Depth>0.52"
Flow Length=1,670'
Tc=18.0 min
1 CN=61
A'
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 7
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-1:
Inflow Area = 15.300 ac, Inflow Depth > 0.52" for 2 YR 24 HR event
Inflow = 8.30 cfs @ 12.14 hrs, Volume= 0.666 of
Outflow = 8.05 cfs @ 12.19 hrs, Volume= 0.664 af, Atten= 3%, Lag= 3.1 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 5.18 fps, Min. Travel Time= 1.6 min
Avg. Velocity = 2.46 fps, Avg. Travel Time= 3.4 min
Peak Storage= 794 cf @ 12.16 hrs, Average Depth at Peak Storage= 0.47'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 187.87 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.07' Top Width= 14.00'
Length= 500.0' Slope= 0.0680 '/'
Inlet Invert= 440.00', Outlet Invert= 406.00'
9
8
7
6
w
u 5
3
0
LL 4
3
2
1
Reach DC-1:
Hydrograph
r�
1
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 8
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-2:
Inflow Area = 6.600 ac, Inflow Depth > 0.52" for 2 YR 24 HR event
Inflow = 3.54 cfs @ 12.14 hrs, Volume= 0.287 of
Outflow = 3.49 cfs @ 12.17 hrs, Volume= 0.287 af, Atten= 1%, Lag= 1.4 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 4.12 fps, Min. Travel Time= 0.8 min
Avg. Velocity = 1.87 fps, Avg. Travel Time= 1.8 min
Peak Storage= 172 cf @ 12.15 hrs, Average Depth at Peak Storage= 0.30'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 190.62 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.0 7' Top Width= 14.00'
Length= 200.0' Slope= 0.0700 7'
Inlet Invert= 420.00', Outlet Invert= 406.00'
Reach DC-2:
Hydrograph
❑ Inflow
3.54 cfs'. ❑ outflow
3.49cfs Inflow Area=6.600 ac
pth=0.30' Avg. De
3
Max VeI=4.1'2 fps
n=0.035
3 2 L=200.0'
" S=0.0700 T
Capacity=190.62 cfs
1
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 11 24-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 9
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond SB-1: Sediment Basin 1
[82] Warning: Early inflow requires earlier time span
Inflow Area =
22.350 ac,
Inflow Depth > 0.57"
for 2 YR 24 HR event
Inflow =
11.74 cfs @
12.18 hrs,
Volume=
1.066 of
Outflow =
0.23 cfs @
11.80 hrs,
Volume=
0.169 af, Atten= 98%, Lag= 0.0 min
Primary =
0.23 cfs @
11.80 hrs,
Volume=
0.169 of
Secondary =
0.00 cfs @
5.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 401.18' @ 20.00 hrs Surf.Area= 9,504 sf Storage= 39,036 cf
Plug -Flow detention time= 237.9 min calculated for 0.169 of (16% of inflow)
Center -of -Mass det. time= 97.6 min ( 932.6 - 835.1 )
Volume Invert Avail.Storage Storage Description
#1 396.00' 132,700 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
396.00 5,700 0 0
398.00 7,100 12,800 12,800
400.00 8,500 15,600 28,400
402.00 10,200 18,700 47,100
404.00 12,300 22,500 69,600
406.00 15,700 28,000 97,600
408.00 19,400 35,100 132,700
Device Routing Invert Outlet Devices
#1 Primary 396.00' 24.0" x 110.0' long Culvert CPP, mitered to conform to fill, Ke= 0.700
Outlet Invert= 395.00' S= 0.0091 T Cc= 0.900
n= 0.013 Corrugated PE, smooth interior
#2 Device 1 396.10' Special & User -Defined
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 0.230 0.230 0.230 0.230
#3 Device 1 406.00' 36.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600
#4 Secondary 407.00' 20.0' long x 10.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=0.23 cfs @ 11.80 hrs HW=396.25' (Free Discharge)
L1=Culvert (Passes 0.23 cfs of 0.34 cfs potential flow)
t2=Special & User -Defined (Custom Controls 0.23 cfs)
3=Orifice/Grate
( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=396.00' (Free Discharge)
t-4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 10
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
fl
0.00 cfs
Pond SB-1: Sediment Basin 1
Hydrograph
11.74 cfs.
flow
-
2.350-
LEInflow
ary------1'nflIIwAre�=2
AC
ondary
Peak- Bev' =--1.1$`
ge-, 39Q36 S#ara - cf
0.23 cfs
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 11
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 2S: Sediment Basin Area Runoff Area=0.450 ac Runoff Depth>4.52"
Tc=0.0 min CN=98 Runoff=3.72 cfs 0.170 of
Subcatchment DA-1: Runoff Area=15.300 ac Runoff Depth>1.31"
Flow Length=1,010' Tc=17.7 min CN=61 Runoff=24.75 cfs 1.673 of
Subcatchment DA-2: Runoff Area=6.600 ac Runoff Depth>1.31"
Flow Length=1,670' Tc=18.0 min CN=61 Runoff=10.57 cfs 0.722 of
Reach DC-1: Avg. Depth=0.80' Max Vet=6.95 fps Inflow=24.75 cfs 1.673 of
n=0.035 L=500.0' S=0.0680 '/' Capacity=187.87 cfs Outflow=24.15 cfs 1.669 of
Reach DC-2: Avg. Depth=0.52' Max Vet=5.59 fps Inflow=10.57 cfs 0.722 of
n=0.035 L=200.0' S=0.0700 '/' Capacity=190.62 cfs Outflow=10.41 cfs 0.721 of
Pond SB-1: Sediment Basin 1 Peak Elev=406.09' Storage=99,033 cf Inflow=34.90 cfs 2.559 of
Primary=1.08 cfs 0.287 of Secondary=0.00 cfs 0.000 of Outflow=1.08 cfs 0.287 of
Total Runoff Area = 22.350 ac Runoff Volume = 2.564 of Average Runoff Depth = 1.38"
97.99% Pervious Area = 21.900 ac 2.01 % Impervious Area = 0.450 ac

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 12
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 2S: Sediment Basin Area
[46] Hint: Tc=O (Instant runoff peak depends on dt)
Runoff = 3.72 cfs @ 11.89 hrs, Volume= 0.170 af, Depth> 4.52"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10 YR 24 HR Rainfall=5.17"
Area (ac) CN Description
0.450 98 Paved parking & roofs
0.450 Impervious Area
Subcatchment 2S: Sediment Basin Area
Hydrograph
4 I ❑Runoff
3.72 cfs
Type 11 24-h r 10 YR 24 HR
Rainfall=5.17"
3 Runoff Area=0.450 ac
Runoff Volume=0.170 of
Runoff Depth,>4.52"
2 Tc=0.0 min
U-
CN-98
1
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 13
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-1:
Runoff = 24.75 cfs @ 12.12 hrs, Volume= 1.673 af, Depth> 1.31"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10 YR 24 HR Rainfall=5.17"
Area (ac) CN Description
15.300 61 >75% Grass cover, Good, HSG B
15.300 Pervious Area
Tc Length
Slope
Velocity Capacity
Description
(min) (feet)
(ft/ft)
(ft/sec) (cfs)
11.7 300
0.1000
0.43
Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
6.0 710
0.0800
1.98
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fDs
17.7 1,010 Total
Subcatchment DA-1:
Hydrograph
26 24.75 cfs
24 ',
::Type 1124-h r 1 Q YR', 24 H R
-
22 Rainfall'= 5.1'7n
20 Run'o- _ac
off -Area,' 5.: QQ_��
Runoff-Vol-ume=-1'.673 of
18
Runo#f -Depth'>1. 1"
w 16
w -
U
3 14
-tET1ii'� ;0'� 01
LL
12 -- Flow
Len:
� 17
10 = .7 min
6
4
2
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 14
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-2:
Runoff = 10.57 cfs @ 12.12 hrs, Volume= 0.722 af, Depth> 1.31"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10 YR 24 HR Rainfall=5.17"
Area (ac) CN Description
6.600 61 >75% Grass cover, Good, HSG B
6.600 Pervious Area
Tc Length
Slope
Velocity Capacity
Description
(min) (feet)
(ft/ft)
(ft/sec) (cfs)
7.3 210
0.1600
0.48
Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
10.7 1,460
0.0230
2.27
Shallow Concentrated Flow,
Grassed Waterwav Kv= 15.0 fos
18.0 1,670 Total
Subcatchment DA-2:
Hydrograph
11 10.57 cfs
We- H-24-h r 1 O- 2$ W R
10
Rain
9fall=5.i7"
I I
Runoff 'Area=6.',6 00-'ac
8
Runoff-V l-ume=-0'.722', of
Ru no#f -De th
7 �y
U >7.J
3 --- Flow L-en'gfh1 -16701-
LL 5
Tc='I $.0 mi n
4
N-61-
3
2
1 LLL
I I I
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 15
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-1:
Inflow Area = 15.300 ac, Inflow Depth > 1.31" for 10 YR 24 HR event
Inflow = 24.75 cfs @ 12.12 hrs, Volume= 1.673 of
Outflow = 24.15 cfs @ 12.16 hrs, Volume= 1.669 af, Atten= 2%, Lag= 2.3 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 6.95 fps, Min. Travel Time= 1.2 min
Avg. Velocity = 3.09 fps, Avg. Travel Time= 2.7 min
Peak Storage= 1,761 cf @ 12.13 hrs, Average Depth at Peak Storage= 0.80'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 187.87 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.0 7' Top Width= 14.00'
Length= 500.0' Slope= 0.0680 7'
Inlet Invert= 440.00', Outlet Invert= 406.00'
Reach DC-1:
Hydrograph
❑ Inflow
24.75 cfs ❑ outflow
26 24.15 cfs Inflow Area=15.300 ac
24
22
Avg. Depth=0.80'
20 Max Vet=6.95 fps
18
n=0.035
w 16
3 14
L=500.0'
12 -
5=0.0680 T
10
C'
a acity=187.87 cfs
a
4
2
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 16
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-2:
Inflow Area = 6.600 ac, Inflow Depth > 1.31" for 10 YR 24 HR event
Inflow = 10.57 cfs @ 12.12 hrs, Volume= 0.722 of
Outflow = 10.41 cfs @ 12.14 hrs, Volume= 0.721 af, Atten= 2%, Lag= 1.2 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 5.59 fps, Min. Travel Time= 0.6 min
Avg. Velocity = 2.39 fps, Avg. Travel Time= 1.4 min
Peak Storage= 375 cf @ 12.13 hrs, Average Depth at Peak Storage= 0.52'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 190.62 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.07' Top Width= 14.00'
Length= 200.0' Slope= 0.0700 '/'
Inlet Invert= 420.00', Outlet Invert= 406.00'
11
10
9
8
7
w
3 6
0
LL 5
4
3
2
1
0
5
Reach DC-2:
Hydrograph
10.57 cfs
10.41 cfs
Inflow Area=6.600 ac
Avg. Depth=0.52'
Max Vet=5.59 fps
n=0.035
L=200.0'
S=0.0700 T
Capacity=190.62 cfs
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Inflow
❑ Outflow

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 11 24-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 17
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond SB-1: Sediment Basin 1
[61] Hint: Submerged 1% of Reach DC-2 bottom
Inflow Area =
22.350 ac,
Inflow Depth > 1.37"
for 10 YR 24 HR event
Inflow =
34.90 cfs @
12.15 hrs,
Volume=
2.559 of
Outflow =
1.08 cfs @
19.32 hrs,
Volume=
0.287 af, Atten= 97%, Lag= 429.9 min
Primary =
1.08 cfs @
19.32 hrs,
Volume=
0.287 of
Secondary =
0.00 cfs @
5.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 406.09' @ 19.32 hrs Surf.Area= 15,868 sf Storage= 99,033 cf
Plug -Flow detention time= 310.2 min calculated for 0.287 of (11 % of inflow)
Center -of -Mass det. time= 184.0 min ( 1,002.3 - 818.3 )
Volume Invert
Avail.Storage Storage Description
#1 396.00'
132,700 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft) (cubic -feet) (cubic -feet)
396.00
5,700 0 0
398.00
7,100 12,800 12,800
400.00
8,500 15,600 28,400
402.00
10,200 18,700 47,100
404.00
12,300 22,500 69,600
406.00
15,700 28,000 97,600
408.00
19,400 35,100 132,700
Device Routing
Invert Outlet Devices
#1 Primary
396.00' 24.0" x 110.0' long Culvert CPP, mitered to conform to fill, Ke= 0.700
Outlet Invert= 395.00' S= 0.0091 T Cc= 0.900
n= 0.013 Corrugated PE, smooth interior
#2 Device 1
396.10' Special & User -Defined
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 0.230 0.230 0.230 0.230
#3 Device 1
406.00' 36.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600
#4 Secondary
407.00' 20.0' long x 10.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=1.07 cfs @ 19.32 hrs HW=406.09' (Free Discharge)
L1=Culvert (Passes 1.07 cfs of 40.24 cfs potential flow)
t2=Special & User -Defined (Custom Controls 0.23 cfs)
3=Orifice/Grate (Weir Controls 0.84 cfs @ 0.99 fps)
Secondary OutFlow
Max=0.00 cfs @ 5.00 hrs HW=396.00' (Free Discharge)
t-4=Broad-Crested
Rectangular Weir ( Controls 0.00 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 18
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond SB-1: Sediment Basin 1
Hydrograph
■ Inflow
0.00 cfs
1.08 cfs
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6.11 "
Prepared by {enter your company name here} Page 19
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 2S: Sediment Basin Area Runoff Area=0.450 ac Runoff Depth>5.37"
Tc=0.0 min CN=98 Runoff=4.40 cfs 0.201 of
Subcatchment DA-1: Runoff Area=15.300 ac Runoff Depth>1.87"
Flow Length=1,010' Tc=17.7 min CN=61 Runoff=36.24 cfs 2.385 of
Subcatchment DA-2: Runoff Area=6.600 ac Runoff Depth>1.87"
Flow Length=1,670' Tc=18.0 min CN=61 Runoff=15.48 cfs 1.029 of
Reach DC-1: Avg. Depth=0.96' Max Vet=7.67 fps Inflow=36.24 cfs 2.385 of
n=0.035 L=500.0' S=0.0680 '/' Capacity=187.87 cfs Outflow=35.40 cfs 2.380 of
Reach DC-2: Avg. Depth=0.64' Max Vet=6.20 fps Inflow=15.48 cfs 1.029 of
n=0.035 L=200.0' S=0.0700 '/' Capacity=190.62 cfs Outflow=15.25 cfs 1.028 of
Pond SB-1: Sediment Basin 1 Peak Elev=406.24' Storage=101,456 cf Inflow=51.06 cfs 3.609 of
Primary=3.98 cfs 1.330 of Secondary=0.00 cfs 0.000 of Outflow=3.98 cfs 1.330 of
Total Runoff Area = 22.350 ac Runoff Volume = 3.615 of Average Runoff Depth = 1.94"
97.99% Pervious Area = 21.900 ac 2.01 % Impervious Area = 0.450 ac

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 20
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 2S: Sediment Basin Area
[46] Hint: Tc=O (Instant runoff peak depends on dt)
Runoff = 4.40 cfs @ 11.89 hrs, Volume= 0.201 af, Depth> 5.37"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25 YR 24 HR Rainfall=6.11"
Area (ac) CN Description
0.450 98 Paved parking & roofs
0.450 Impervious Area
Subcatchment 2S: Sediment Basin Area
Hydrograph
', ❑Runoff
4.40 cfs
Type II 24-hr 25 YR 24 HR
4 Rainfall=6.11"
Runoff Area=0.450 ac
3 Runoff Volume=0:201 of
Runoff Depth',>5.37"
Tc=0.0 min
U-
2 CN=98
11 1 ri-�
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6.11 "
Prepared by {enter your company name here} Page 21
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-1:
Runoff = 36.24 cfs @ 12.11 hrs, Volume= 2.385 af, Depth> 1.87"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25 YR 24 HR Rainfall=6.11"
Area (ac) CN Description
15.300 61 >75% Grass cover, Good, HSG B
15.300 Pervious Area
Tc Length Slope Velocity
min) (feet) (ft/ft) (ft/sec)
11.7 300 0.1000 0.43
6.0 710 0.0800 1.98
17.7 1,010 Total
Capacity Description
(cfs)
Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fDs
■ Runoff

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 22
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-2:
Runoff = 15.48 cfs @ 12.12 hrs, Volume= 1.029 af, Depth> 1.87"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25 YR 24 HR Rainfall=6.11"
Area (ac) CN Description
6.600 61 >75% Grass cover, Good, HSG B
6.600 Pervious Area
Tc Length
(min) (feet)
Slope
(ft/ft)
Velocity Capacity
(ft/sec) (cfs)
Description
7.3 210
0.1600
0.48
Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
10.7 1,460
0.0230
2.27
Shallow Concentrated Flow,
Grassed Waterwav Kv= 15.0 fos
18.0 1,670 Total
■ Runoff
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6.11 "
Prepared by {enter your company name here} Page 23
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-1:
Inflow Area = 15.300 ac, Inflow Depth > 1.87" for 25 YR 24 HR event
Inflow = 36.24 cfs @ 12.11 hrs, Volume= 2.385 of
Outflow = 35.40 cfs @ 12.15 hrs, Volume= 2.380 af, Atten= 2%, Lag= 2.1 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 7.67 fps, Min. Travel Time= 1.1 min
Avg. Velocity = 3.31 fps, Avg. Travel Time= 2.5 min
Peak Storage= 2,334 cf @ 12.13 hrs, Average Depth at Peak Storage= 0.96'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 187.87 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.07' Top Width= 14.00'
Length= 500.0' Slope= 0.0680 '/'
Inlet Invert= 440.00', Outlet Invert= 406.00'
w -
u 2
3 2
0 1
if:
1
1
1
1
7
8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Inflow
❑ Outflow

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 24
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-2:
Inflow Area = 6.600 ac, Inflow Depth > 1.87" for 25 YR 24 HR event
Inflow = 15.48 cfs @ 12.12 hrs, Volume= 1.029 of
Outflow = 15.25 cfs @ 12.13 hrs, Volume= 1.028 af, Atten= 1 %, Lag= 1.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 6.20 fps, Min. Travel Time= 0.5 min
Avg. Velocity = 2.58 fps, Avg. Travel Time= 1.3 min
Peak Storage= 497 cf @ 12.12 hrs, Average Depth at Peak Storage= 0.64'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 190.62 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.0 7' Top Width= 14.00'
Length= 200.0' Slope= 0.0700 7'
Inlet Invert= 420.00', Outlet Invert= 406.00'
Reach DC-2:

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 11 24-hr 25 YR 24 HR Rainfall=6.11 "
Prepared by {enter your company name here} Page 25
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond SB-1: Sediment Basin 1
[61] Hint: Submerged 1% of Reach DC-1 bottom
[61] Hint: Submerged 2% of Reach DC-2 bottom
Inflow Area = 22.350 ac, Inflow Depth > 1.94" for 25 YR 24 HR event
Inflow = 51.06 cfs @ 12.14 hrs, Volume= 3.609 of
Outflow = 3.98 cfs @ 13.77 hrs, Volume= 1.330 af, Atten= 92%, Lag= 97.5 min
Primary = 3.98 cfs @ 13.77 hrs, Volume= 1.330 of
Secondary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 406.24' @ 13.77 hrs Surf.Area= 16,148 sf Storage= 101,456 cf
Plug -Flow detention time= 233.1 min calculated for 1.325 of (37% of inflow)
Center -of -Mass det. time= 138.6 min ( 950.6 - 812.0 )
Volume Invert Avail.Storage Storage Description
#1 396.00' 132,700 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
396.00 5,700 0 0
398.00 7,100 12,800 12,800
400.00 8,500 15,600 28,400
402.00 10,200 18,700 47,100
404.00 12,300 22,500 69,600
406.00 15,700 28,000 97,600
408.00 19,400 35,100 132,700
Device Routing Invert Outlet Devices
#1 Primary 396.00' 24.0" x 110.0' long Culvert CPP, mitered to conform to fill, Ke= 0.700
Outlet Invert= 395.00' S= 0.0091 T Cc= 0.900
n= 0.013 Corrugated PE, smooth interior
#2 Device 1 396.10' Special & User -Defined
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 0.230 0.230 0.230 0.230
#3 Device 1 406.00' 36.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600
#4 Secondary 407.00' 20.0' long x 10.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=3.90 cfs @ 13.77 hrs HW=406.24' (Free Discharge)
L1=Culvert (Passes 3.90 cfs of 40.58 cfs potential flow)
t2=Special & User -Defined (Custom Controls 0.23 cfs)
3=Orifice/Grate
(Weir Controls 3.67 cfs @ 1.61 fps)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=396.00' (Free Discharge)
't�=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Sediment Basin 1 - Post Mine Reclamation (Worst Case)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 26
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond SB-1: Sediment Basin 1

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
12S
11 P Excavated Pond Area
Exc ated Pond
1 S 9P o-- DC-3 4- DA-3
Pump Basin Area Pump Basin
SUbCa Reach and Link Drainage Diagram for Merrits Gravel Pit - Basin
Prepared by {enter your company name here} 10/28/2021
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin
Prepared by {enter your company name here} Page 2
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Area Listing (selected nodes)
Area (acres) CN Description (subcats)
0.800 49 50-75% Grass cover, Fair, HSG A (DA-3)
0.140 98 Paved parking & roofs (1S)
11.019 98 Paved roads w/curbs & sewers (12S)
11.959

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 3
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pump Basin Area
Runoff Area=0.140 ac Runoff Depth>3.08"
Tc=0.0 min CN=98 Runoff=0.80 cfs 0.036 of
Subcatchment 12S: Excavated Pond Area Runoff Area=480,000 sf Runoff Depth>3.08"
Tc=5.0 min CN=98 Runoff=56.33 cfs 2.828 of
Subcatchment DA-3: Runoff Area=0.800 ac Runoff Depth>0.15"
Flow Length=160' Slope=0.3100 '/' Tc=4.5 min CN=49 Runoff=0.06 cfs 0.010 of
Reach DC-3: Avg. Depth=0.02' Max Vet=0.67 fps Inflow=0.06 cfs 0.010 of
n=0.035 L=750.0' S=0.0480 '/' Capacity=157.84 cfs Outflow=0.03 cfs 0.009 of
Pond 9P: Pump Basin Peak EIev=408.48' Storage=9,516 cf Inflow=6.95 cfs 2.870 of
Primary=6.83 cfs 2.684 of Secondary=0.00 cfs 0.000 of Outflow=6.83 cfs 2.684 of
Pond 11 P: Excavated Pond Peak EIev=370.24' Storage=44,402 cf Inflow=56.33 cfs 2.828 of
Outflow=6.15 cfs 2.824 of
Total Runoff Area = 11.959 ac Runoff Volume = 2.874 of Average Runoff Depth = 2.88"
6.69% Pervious Area = 0.800 ac 93.31% Impervious Area = 11.159 ac

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 4
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 1S: Pump Basin Area
[46] Hint: Tc=O (Instant runoff peak depends on dt)
Runoff = 0.80 cfs @ 11.89 hrs, Volume= 0.036 af, Depth> 3.08"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 2 YR 24 HR Rainfall=3.57"
Area (ac) CN Description
0.140 98 Paved parking & roofs
0.140 Impervious Area
Subcatchment 1S: Pump Basin Area
Hydrograph
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 5
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 12S: Excavated Pond Area
[49] Hint: Tc<2dt may require smaller dt
Runoff = 56.33 cfs @ 11.95 hrs, Volume= 2.828 af, Depth> 3.08"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 2 YR 24 HR Rainfall=3.57"
Area (sf) CN Description
480,000 98 Paved roads w/curbs & sewers
480,000 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 12S: Excavated Pond Area
Hydrograph
60 ', ', ', ■Runoff
56.33 cfs
55
Type 11 ',24hr 2YR 24 HR
Rain 50 fall"3.57"
45 Runoff Area =480,,000,-sf
40 Runoff Vo1ume_=2.828: af__
" 35 0.8"
Runoff Dspth>3.
° 30 Tc-5 LL .0 min
25
w'
I CN=-9B
20
15
10
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 6
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-3:
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.06 cfs @ 12.02 hrs, Volume= 0.010 af, Depth> 0.15"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 2 YR 24 HR Rainfall=3.57"
Area (ac) CN Description
0.800 49 50-75% Grass cover, Fair, HSG A
0.800 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
4.5 160 0.3100 0.59 Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
Subcatchment DA-3:
Hydrograph
■ Runoff
0.06
.055
0.05
0.02
0.015
0.01
0.06 cfs
24 Type II', 24- - W R
-
hr 2' YR,
RainfalIj —3 7
Ru n'off -Area=0,800-'ac
Runoff Volume=0 010-af
Runoff -Depth>0.45•'
Flow�'- Le ngth=1 601
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 7
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-3:
Inflow Area = 0.800 ac, Inflow Depth > 0.15" for 2 YR 24 HR event
Inflow = 0.06 cfs @ 12.02 hrs, Volume= 0.010 of
Outflow = 0.03 cfs @ 12.80 hrs, Volume= 0.009 af, Atten= 54%, Lag= 46.6 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.67 fps, Min. Travel Time= 18.5 min
Avg. Velocity = 0.67 fps, Avg. Travel Time= 18.6 min
Peak Storage= 31 cf @ 12.49 hrs, Average Depth at Peak Storage= 0.02'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 157.84 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.07' Top Width= 14.00'
Length= 750.0' Slope= 0.0480 '/'
Inlet Invert= 442.00', Outlet Invert= 406.00'
Reach DC-3:
Hydrograph
0.06 cfs
0.065
Inflow Area=0.800 ac
0.06
0.055
Avg. Depth=0.02'
0.05
Max Vet=0.67 fps
0.045
n=0.035
N 0.04
v 0.035
L=750.0'
3
0
LL 0.03
0.03 cfs g=0.0480 T
0.025
city=157.84 cfs
002
0.015
0.01
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Inflow
❑ Outflow

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 11 24-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 8
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 9P: Pump Basin
[82] Warning: Early inflow requires earlier time span
[61] Hint: Submerged 7% of Reach DC-3 bottom
[78] Warning: Submerged Pond 11 P Primary device # 1 by 38.48'
[81] Warning: Exceeded Pond 11 P by 38.43' @ 15.20 hrs
Inflow Area = 11.959 ac, Inflow Depth > 2.88" for 2 YR 24 HR event
Inflow = 6.95 cfs @ 11.89 hrs, Volume= 2.870 of
Outflow = 6.83 cfs @ 11.92 hrs, Volume= 2.684 af, Atten= 2%, Lag= 1.8 min
Primary = 6.83 cfs @ 11.92 hrs, Volume= 2.684 of
Secondary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 408.48' @ 11.92 hrs Surf.Area= 3,770 sf Storage= 9,516 cf
Plug -Flow detention time= 50.0 min calculated for 2.684 of (94% of inflow)
Center -of -Mass det. time= 27.8 min ( 806.1 - 778.3 )
Volume Invert Avail.Storage Storage Description
#1 404.00' 16,314 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
404.00 750 0 0
406.00 1,868 2,618 2,618
408.00 3,336 5,204 7,822
410.00 5,156 8,492 16,314
Device Routing Invert Outlet Devices
#1 Primary 404.00' 18.0" x 50.0' long Culvert CPP, mitered to conform to fill, Ke= 0.700
Outlet Invert= 403.00' S= 0.02007' Cc= 0.900
n= 0.020 Corrugated PE, corrugated interior
#2 Device 1 404.10' Special & User -Defined
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 0.038 0.038 0.038 0.038
#3 Device 1 408.00' 24.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600
#4 Secondary 409.00' 20.0' long x 10.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=6.78 cfs @ 11.92 hrs HW=408.48' (Free Discharge)
L1=Culvert (Passes 6.78 cfs of 14.38 cfs potential flow)
t2=Special & User -Defined (Custom Controls 0.04 cfs)
3=Orifice/Grate
(Weir Controls 6.74 cfs @ 2.26 fps)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=404.01' (Free Discharge)
t-4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 9
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 9P: Pump Basin
Hydrograph
6.95 cfs ❑ Inflow
❑ Outflow
fs Inflow Area=11.959 ac o se Secondary
6.83 cfs
k Elev=408.48'
orage=9,516 cf
5
w
u
�. 4
3
o
LL
3
2
///

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 10
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 11 P: Excavated Pond
[82] Warning: Early inflow requires earlier time span
Inflow Area =
11.019 ac,
Inflow Depth > 3.08"
for 2 YR 24 HR event
Inflow =
56.33 cfs @
11.95 hrs, Volume=
2.828 of
Outflow =
6.15 cfs @
11.90 hrs, Volume=
2.824 af, Atten= 89%, Lag= 0.0 min
Primary =
6.15 cfs @
11.90 hrs, Volume=
2.824 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 370.24' @ 12.28 hrs Surf.Area= 188,731 sf Storage= 44,402 cf
Plug -Flow detention time= 47.7 min calculated for 2.824 of (100% of inflow)
Center -of -Mass det. time= 46.9 min ( 778.4 - 731.5 )
Volume Invert Avail.Storage Storage Description
#1 370.00' 13,340,000 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
370.00 187,000 0 0
410.00 480,000 13,340,000 13,340,000
Device Routing Invert Outlet Devices
#1 Primary 370.00' Pump
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 6.150 6.150 6.150 6.150
Primary OutFlow Max=6.15 cfs @ 11.90 hrs HW=370.10' (Free Discharge)
L1=Pump (Custom Controls 6.15 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 11
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 11 P: Excavated Pond
Hydrograph
■ Inflow
❑Primary 1
1.019 ac
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 12
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pump Basin Area
Runoff Area=0.140 ac Runoff Depth>4.52"
Tc=0.0 min CN=98 Runoff=1.16 cfs 0.053 of
Subcatchment 12S: Excavated Pond Area Runoff Area=480,000 sf Runoff Depth>4.52"
Tc=5.0 min CN=98 Runoff=81.99 cfs 4.153 of
Subcatchment DA-3: Runoff Area=0.800 ac Runoff Depth>0.61"
Flow Length=160' Slope=0.3100 '/' Tc=4.5 min CN=49 Runoff=0.82 cfs 0.041 of
Reach DC-3: Avg. Depth=0.12' Max Vet=2.02 fps Inflow=0.82 cfs 0.041 of
n=0.035 L=750.0' S=0.0480 '/' Capacity=157.84 cfs Outflow=0.55 cfs 0.040 of
Pond 9P: Pump Basin Peak EIev=408.49' Storage=9,570 cf Inflow=7.31 cfs 4.240 of
Primary=7.14 cfs 4.052 of Secondary=0.00 cfs 0.000 of Outflow=7.14 cfs 4.052 of
Pond 11 P: Excavated Pond Peak EIev=370.39' Storage=72,769 cf Inflow=81.99 cfs 4.153 of
Outflow=6.15 cfs 4.148 of
Total Runoff Area = 11.959 ac Runoff Volume = 4.246 of Average Runoff Depth = 4.26"
6.69% Pervious Area = 0.800 ac 93.31% Impervious Area = 11.159 ac

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 13
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 1S: Pump Basin Area
[46] Hint: Tc=O (Instant runoff peak depends on dt)
Runoff = 1.16 cfs @ 11.89 hrs, Volume= 0.053 af, Depth> 4.52"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10 YR 24 HR Rainfall=5.17"
Area (ac) CN Description
0.140 98 Paved parking & roofs
0.140 Impervious Area
Subcatchment 1S: Pump Basin Area
Hydrograph
', ' ' ', ', ❑Runoff
1.16 cfs
Type II 24-hr 10 YR 24 HR
1 Rainfall=5.17"
Runoff Area=0.140 ac
Runoff Volume=0.053 of
Runoff Depth',>4.52"
Tc=0.0 min
U-
CN=98
rj
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 14
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 12S: Excavated Pond Area
[49] Hint: Tc<2dt may require smaller dt
Runoff = 81.99 cfs @ 11.95 hrs, Volume= 4.153 af, Depth> 4.52"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10 YR 24 HR Rainfall=5.17"
Area (sf) CN Description
480,000 98 Paved roads w/curbs & sewers
480,000 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
N
U
3
0
LL
I
Subcatchment 12S: Excavated Pond Area
Hydrograph
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 15
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-3:
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.82 cfs @ 11.98 hrs, Volume= 0.041 af, Depth> 0.61"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10 YR 24 HR Rainfall=5.17"
Area (ac) CN Description
0.800 49 50-75% Grass cover, Fair, HSG A
0.800 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
4.5 160 0.3100 0.59 Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
Subcatchment DA-3:

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 16
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-3:
Inflow Area = 0.800 ac, Inflow Depth > 0.61" for 10 YR 24 HR event
Inflow = 0.82 cfs @ 11.98 hrs, Volume= 0.041 of
Outflow = 0.55 cfs @ 12.15 hrs, Volume= 0.040 af, Atten= 32%, Lag= 10.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 2.02 fps, Min. Travel Time= 6.2 min
Avg. Velocity = 0.84 fps, Avg. Travel Time= 14.8 min
Peak Storage= 207 cf @ 12.04 hrs, Average Depth at Peak Storage= 0.12'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 157.84 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.07' Top Width= 14.00'
Length= 750.0' Slope= 0.0480 '/'
Inlet Invert= 442.00', Outlet Invert= 406.00'
Reach DC-3:

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 17
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 9P: Pump Basin
[82] Warning: Early inflow requires earlier time span
[61] Hint: Submerged 7% of Reach DC-3 bottom
[78] Warning: Submerged Pond 11 P Primary device # 1 by 38.49'
[81] Warning: Exceeded Pond 11 P by 38.44' @ 11.60 hrs
Inflow Area = 11.959 ac, Inflow Depth > 4.25" for 10 YR 24 HR event
Inflow = 7.31 cfs @ 11.89 hrs, Volume= 4.240 of
Outflow = 7.14 cfs @ 11.92 hrs, Volume= 4.052 af, Atten= 2%, Lag= 1.8 min
Primary = 7.14 cfs @ 11.92 hrs, Volume= 4.052 of
Secondary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 408.49' @ 11.92 hrs Surf.Area= 3,783 sf Storage= 9,570 cf
Plug -Flow detention time= 37.2 min calculated for 4.038 of (95% of inflow)
Center -of -Mass det. time= 22.9 min ( 834.8 - 811.9 )
Volume Invert Avail.Storage Storage Description
#1 404.00' 16,314 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
404.00 750 0 0
406.00 1,868 2,618 2,618
408.00 3,336 5,204 7,822
410.00 5,156 8,492 16,314
Device Routing Invert Outlet Devices
#1 Primary 404.00' 18.0" x 50.0' long Culvert CPP, mitered to conform to fill, Ke= 0.700
Outlet Invert= 403.00' S= 0.02007' Cc= 0.900
n= 0.020 Corrugated PE, corrugated interior
#2 Device 1 404.10' Special & User -Defined
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 0.038 0.038 0.038 0.038
#3 Device 1 408.00' 24.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600
#4 Secondary 409.00' 20.0' long x 10.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=7.08 cfs @ 11.92 hrs HW=408.49' (Free Discharge)
L1=Culvert (Passes 7.08 cfs of 14.41 cfs potential flow)
t2=Special & User -Defined (Custom Controls 0.04 cfs)
3=Orifice/Grate
(Weir Controls 7.05 cfs @ 2.29 fps)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=404.02' (Free Discharge)
t-4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 18
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 9P: Pump Basin
Hydrograph
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 19
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 11 P: Excavated Pond
[82] Warning: Early inflow requires earlier time span
Inflow Area =
11.019 ac,
Inflow Depth > 4.52"
for 10 YR 24 HR event
Inflow =
81.99 cfs @
11.95 hrs, Volume=
4.153 of
Outflow =
6.15 cfs @
11.85 hrs, Volume=
4.148 af, Atten= 92%, Lag= 0.0 min
Primary =
6.15 cfs @
11.85 hrs, Volume=
4.148 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 370.39' @ 12.49 hrs Surf.Area= 189,829 sf Storage= 72,769 cf
Plug -Flow detention time= 84.5 min calculated for 4.133 of (100% of inflow)
Center -of -Mass det. time= 83.4 min ( 812.6 - 729.2 )
Volume Invert Avail.Storage Storage Description
#1 370.00' 13,340,000 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
370.00 187,000 0 0
410.00 480,000 13,340,000 13,340,000
Device Routing Invert Outlet Devices
#1 Primary 370.00' Pump
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 6.150 6.150 6.150 6.150
Primary OutFlow Max=6.15 cfs @ 11.85 hrs HW=370.12' (Free Discharge)
L1=Pump (Custom Controls 6.15 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 20
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 11 P: Excavated Pond
Hydrograph
■ Inflow
❑ Primary
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 21
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pump Basin Area
Runoff Area=0.140 ac Runoff Depth>5.37"
Tc=0.0 min CN=98 Runoff=1.37 cfs 0.063 of
Subcatchment 12S: Excavated Pond Area Runoff Area=480,000 sf Runoff Depth>5.37"
Tc=5.0 min CN=98 Runoff=97.03 cfs 4.928 of
Subcatchment DA-3: Runoff Area=0.800 ac Runoff Depth>0.98"
Flow Length=160' Slope=0.3100 '/' Tc=4.5 min CN=49 Runoff=1.47 cfs 0.066 of
Reach DC-3: Avg. Depth=0.18' Max Vet=2.54 fps Inflow=1.47 cfs 0.066 of
n=0.035 L=750.0' S=0.0480 '/' Capacity=157.84 cfs Outflow=1.11 cfs 0.065 of
Pond 9P: Pump Basin Peak EIev=408.50' Storage=9,608 cf Inflow=7.55 cfs 5.049 of
Primary=7.35 cfs 4.860 of Secondary=0.00 cfs 0.000 of Outflow=7.35 cfs 4.860 of
Pond 11 P: Excavated Pond Peak EIev=370.48' Storage=90,453 cf Inflow=97.03 cfs 4.928 of
Outflow=6.15 cfs 4.922 of
Total Runoff Area = 11.959 ac Runoff Volume = 5.057 of Average Runoff Depth = 5.07"
6.69% Pervious Area = 0.800 ac 93.31 % Impervious Area = 11.159 ac

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6.11 "
Prepared by {enter your company name here} Page 22
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 1S: Pump Basin Area
[46] Hint: Tc=O (Instant runoff peak depends on dt)
Runoff = 1.37 cfs @ 11.89 hrs, Volume= 0.063 af, Depth> 5.37"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25 YR 24 HR Rainfall=6.11"
Area (ac) CN Description
0.140 98 Paved parking & roofs
0.140 Impervious Area
Subcatchment 1S: Pump Basin Area
Hydrograph
❑ Runoff
1.37 cfs
Type 11 24-h r 25 YR 24 HR
Rainfall=6.11"
Runoff Area=0.140 ac
1 Runoff Volume=0.063 of
Runoff Depth',>5.37"
Tc=0.0 min
U-
CN=98
rj
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6.11 "
Prepared by {enter your company name here} Page 23
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 12S: Excavated Pond Area
[49] Hint: Tc<2dt may require smaller dt
Runoff = 97.03 cfs @ 11.95 hrs, Volume= 4.928 af, Depth> 5.37"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25 YR 24 HR Rainfall=6.11"
Area (sf) CN Description
480,000 98 Paved roads w/curbs & sewers
480,000 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 12S: Excavated Pond Area
Hydrograph
105
■Runoff
100
95
97.03 cfs
Type 11 24-h'',r-25YR'' 24 H R
90
85
Rainfa11=6.1,1"
80
75
f f Area 480000V=
RU11O'
70
Runoff Vo1ume=4 928'-of
65
60
r
.'
' .
,-
-
R hnoff Depth'>5.3711
55
50
.'�
- - - -r- ---- r
- - - -'- - - - '- - -
- _�
------r------r------'�-- --- --- -F--- --- � - --- -T�5F. 0 -min- -
LL
45
CN�.98
35
- ---r------6
------r------6------d- ----- 'r
30
25
.
20
r I
-
15
,'
r
10
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 24
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-3:
[49] Hint: Tc<2dt may require smaller dt
Runoff = 1.47 cfs @ 11.97 hrs, Volume= 0.066 af, Depth> 0.98"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25 YR 24 HR Rainfall=6.11"
Area (ac) CN Description
0.800 49 50-75% Grass cover, Fair, HSG A
0.800 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
4.5 160 0.3100 0.59 Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
1
w
0
LL
Subcatchment DA-3:
Hydrograph
1.47 cfs
Time (hours)
Type 11 24-h r 25 YR 24 HR
Rainfall=6.11"
Runoff Area=0.800 ac
Runoff Volume=0.066 of
Runoff Depth',>0.98"
Flow Length=160'
Slope=0.3100 '/'
Tc=4.5 m i n
CN=49
❑ Runoff

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 25
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-3:
Inflow Area = 0.800 ac, Inflow Depth > 0.98" for 25 YR 24 HR event
Inflow = 1.47 cfs @ 11.97 hrs, Volume= 0.066 of
Outflow = 1.11 cfs @ 12.11 hrs, Volume= 0.065 af, Atten= 24%, Lag= 8.2 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 2.54 fps, Min. Travel Time= 4.9 min
Avg. Velocity = 0.98 fps, Avg. Travel Time= 12.8 min
Peak Storage= 340 cf @ 12.02 hrs, Average Depth at Peak Storage= 0.18'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 157.84 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.07' Top Width= 14.00'
Length= 750.0' Slope= 0.0480 '/'
Inlet Invert= 442.00', Outlet Invert= 406.00'
1
w
u
3
0
LL
01' 5
Reach DC-3:
Hydrograph
1.47 cfs
Inflow Area=0.800 ac
Avg. Depth=0.18'
1.11 cfs Max Vet=2.54 fps
n=0.035
L=750.0'
S=0.0480 T
Capacity=157.84 cfs
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Inflow
❑ Outflow

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 26
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 9P: Pump Basin
[82] Warning: Early inflow requires earlier time span
[61] Hint: Submerged 7% of Reach DC-3 bottom
[78] Warning: Submerged Pond 11 P Primary device # 1 by 38.50'
[81] Warning: Exceeded Pond 11 P by 38.44' @ 11.55 hrs
Inflow Area = 11.959 ac, Inflow Depth > 5.07" for 25 YR 24 HR event
Inflow = 7.55 cfs @ 11.89 hrs, Volume= 5.049 of
Outflow = 7.35 cfs @ 11.93 hrs, Volume= 4.860 af, Atten= 3%, Lag= 2.1 min
Primary = 7.35 cfs @ 11.93 hrs, Volume= 4.860 of
Secondary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 408.50' @ 11.93 hrs Surf.Area= 3,792 sf Storage= 9,608 cf
Plug -Flow detention time= 33.0 min calculated for 4.844 of (96% of inflow)
Center -of -Mass det. time= 21.1 min ( 856.7 - 835.6 )
Volume Invert Avail.Storage Storage Description
#1 404.00' 16,314 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
404.00 750 0 0
406.00 1,868 2,618 2,618
408.00 3,336 5,204 7,822
410.00 5,156 8,492 16,314
Device Routing Invert Outlet Devices
#1 Primary 404.00' 18.0" x 50.0' long Culvert CPP, mitered to conform to fill, Ke= 0.700
Outlet Invert= 403.00' S= 0.02007' Cc= 0.900
n= 0.020 Corrugated PE, corrugated interior
#2 Device 1 404.10' Special & User -Defined
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 0.038 0.038 0.038 0.038
#3 Device 1 408.00' 24.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600
#4 Secondary 409.00' 20.0' long x 10.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=7.30 cfs @ 11.93 hrs HW=408.50' (Free Discharge)
L1=Culvert (Passes 7.30 cfs of 14.43 cfs potential flow)
t2=Special & User -Defined (Custom Controls 0.04 cfs)
3=Orifice/Grate
(Weir Controls 7.26 cfs @ 2.31 fps)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=404.03' (Free Discharge)
t-4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 27
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 9P: Pump Basin
Hydrograph
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6.11 "
Prepared by {enter your company name here} Page 28
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 11 P: Excavated Pond
[82] Warning: Early inflow requires earlier time span
Inflow Area =
11.019 ac,
Inflow Depth > 5.37"
for 25 YR 24 HR event
Inflow =
97.03 cfs @
11.95 hrs, Volume=
4.928 of
Outflow =
6.15 cfs @
11.80 hrs, Volume=
4.922 af, Atten= 94%, Lag= 0.0 min
Primary =
6.15 cfs @
11.80 hrs, Volume=
4.922 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 370.48' @ 12.57 hrs Surf.Area= 190,510 sf Storage= 90,453 cf
Plug -Flow detention time= 109.4 min calculated for 4.921 of (100% of inflow)
Center -of -Mass det. time= 108.5 min ( 837.0 - 728.4 )
Volume Invert Avail.Storage Storage Description
#1 370.00' 13,340,000 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
370.00 187,000 0 0
410.00 480,000 13,340,000 13,340,000
Device Routing Invert Outlet Devices
#1 Primary 370.00' Pump
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 6.150 6.150 6.150 6.150
Primary OutFlow Max=6.15 cfs @ 11.80 hrs HW=370.10' (Free Discharge)
L1=Pump (Custom Controls 6.15 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Mine Operations)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6.11 "
Prepared by {enter your company name here} Page 29
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 11 P: Excavated Pond
Hydrograph
---
■ Inflow
105
97.03 c fs
Primary
Prima
100
-% .
Inflow Area-11.p'19 aE
95
- -
- - -
90
,.% .
Pear Elev=370.48'
85
"%.-
r r r - r----'r-- - -i- --
80
�ora-9 a gp 53 C
75
70
%"
i
65
60
55
0
',-','
50
i - - - -;- - --
u 45
40
35
- - - - - - - - - - -i-
30
',-','
--- -'-- -- i -- - -'-----'r- - - -i- -'-- -- -- 'r
25
-' .'
- - - - -' 4- - - - - - ---
20
15
"-
10
'' ,
6.15 cfS
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
This page intentionally left blank.

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
is IV\ zqP / pC-3 a- DA-3 Rec
Pump Basin Area Pump Basin
Subca Reach and Link

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin
Prepared by {enter your company name here} Page 2
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Area Listing (selected nodes)
Area (acres) CN Description (subcats)
4.700 39 >75% Grass cover, Good, HSG A (DA-3 Rec)
0.140 98 Paved parking & roofs (1S)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 3
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pump Basin Area Runoff Area=0.140 ac Runoff Depth>3.08"
Tc=0.0 min CN=98 Runoff=0.80 cfs 0.036 of
Subcatchment DA-3 Rec: Runoff Area=4.700 ac Runoff Depth>0.00"
Flow Length=370' Slope=0.0600 '/' Tc=15.1 min CN=39 Runoff=0.01 cfs 0.002 of
Reach DC-3: Avg. Depth=0.01' Max Vet=0.67 fps Inflow=0.01 cfs 0.002 of
n=0.035 L=750.0' S=0.0480 '/' Capacity=157.84 cfs Outflow=0.01 cfs 0.001 of
Pond 9P: Pump Basin Peak Elev=404.80' Storage=776 cf Inflow=0.80 cfs 0.037 of
Primary=0.04 cfs 0.033 of Secondary=0.00 cfs 0.000 of Outflow=0.04 cfs 0.033 of
Total Runoff Area = 4.840 ac Runoff Volume = 0.038 of Average Runoff Depth = 0.09"
97.11 % Pervious Area = 4.700 ac 2.89% Impervious Area = 0.140 ac

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 4
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 1S: Pump Basin Area
[46] Hint: Tc=O (Instant runoff peak depends on dt)
Runoff = 0.80 cfs @ 11.89 hrs, Volume= 0.036 af, Depth> 3.08"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 2 YR 24 HR Rainfall=3.57"
Area (ac) CN Description
0.140 98 Paved parking & roofs
0.140 Impervious Area
Subcatchment 1S: Pump Basin Area
Hydrograph
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 5
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-3 Rec:
[73] Warning: Peak may fall outside time span
Runoff = 0.01 cfs @ 20.00 hrs, Volume= 0.002 af, Depth> 0.00"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 2 YR 24 HR Rainfall=3.57"
Area (ac) CN Description
4.700 39 >75% Grass cover, Good, HSG A
4.700 Pervious Area
Tc Length
Slope
Velocity Capacity
Description
(min) (feet)
(ft/ft)
(ft/sec) (cfs)
14.4 300
0.0600
0.35
Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
0.7 70
0.0600
1.71
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fDs
15.1 370 Total
Subcatchment DA-3 Rec:
Hydrograph
0.008
0.007
0.007
"
YR 24 ',H R
Type- II- 24
0.007
''
Rainfa — ',
0.006
.57
0.006
-Runoff Area=4.700 ac- - - -'.
0.005
Runoff Volurhe=0.002-af
0.005
0.004
Ru_r10 f f De_pth_>000"
0.004
_
370 -Flow-
a 0.003
t
SI oe QO OQO .}
0.003
p
0.002
".'
C
-Tc-�-1-5" 1 min- 4
0.002
"
CiV=3
0.001
0.001
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 6
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-3:
Inflow Area = 4.700 ac, Inflow Depth > 0.00" for 2 YR 24 HR event
Inflow = 0.01 cfs @ 20.00 hrs, Volume= 0.002 of
Outflow = 0.01 cfs @ 20.00 hrs, Volume= 0.001 af, Atten= 3%, Lag= 0.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.67 fps, Min. Travel Time= 18.6 min
Avg. Velocity = 0.67 fps, Avg. Travel Time= 18.6 min
Peak Storage= 8 cf @ 20.00 hrs, Average Depth at Peak Storage= 0.01'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 157.84 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.07' Top Width= 14.00'
Length= 750.0' Slope= 0.0480 '/'
Inlet Invert= 442.00', Outlet Invert= 406.00'
Reach DC-3:
Hydrograph
-----------
■ Inflow
0.01 cfs ■ Outflow
0.01 cfs
0.005
n=0.035
0.005
w
v 0.004
L=750.0" = =
3 0.004
o
0.003
__
S 0.0480
0.003
= Ca acit 157.
p y84 fs
0.002
0.002
0.001
0.001
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 7
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 9P: Pump Basin
[82] Warning: Early inflow requires earlier time span
Inflow Area =
4.840 ac,
Inflow Depth > 0.09"
for 2 YR 24 HR event
Inflow =
0.80 cfs @
11.89 hrs,
Volume=
0.037 of
Outflow =
0.04 cfs @
11.65 hrs,
Volume=
0.033 af, Atten= 95%, Lag= 0.0 min
Primary =
0.04 cfs @
11.65 hrs,
Volume=
0.033 of
Secondary =
0.00 cfs @
5.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 404.80' @ 12.72 hrs Surf.Area= 1,196 sf Storage= 776 cf
Plug -Flow detention time= 188.5 min calculated for 0.033 of (88% of inflow)
Center -of -Mass det. time= 142.0 min ( 883.8 - 741.7 )
Volume Invert Avail.Storage Storage Description
#1 404.00' 16,314 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
404.00 750 0 0
406.00 1,868 2,618 2,618
408.00 3,336 5,204 7,822
410.00 5,156 8,492 16,314
Device Routing Invert Outlet Devices
#1 Primary 404.00' 18.0" x 50.0' long Culvert CPP, mitered to conform to fill, Ke= 0.700
Outlet Invert= 403.00' S= 0.02007' Cc= 0.900
n= 0.020 Corrugated PE, corrugated interior
#2 Device 1 404.10' Special & User -Defined
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 0.038 0.038 0.038 0.038
#3 Device 1 408.00' 24.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600
#4 Secondary 409.00' 20.0' long x 10.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=0.04 cfs @ 11.65 hrs HW=404.20' (Free Discharge)
L1=Culvert (Passes 0.04 cfs of 0.19 cfs potential flow)
t2=Special & User -Defined (Custom Controls 0.04 cfs)
3=Orifice/Grate
( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=404.00' (Free Discharge)
t-4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 8
HydroCAD® 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
0.8
0.
0.7
0.
0.6
0
w I
u
3 0.
o (
U.
0.
0.25
]"",."
0.2
0.15
0.1
0.00 cfs
p: �l
5
■ Inflow
■ Outflow
ff�
■ Primary
.840 cic -_ ■ Secondary
4V4- 801 -
0.04 cfs
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 9
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pump Basin Area Runoff Area=0.140 ac Runoff Depth>4.52"
Tc=0.0 min CN=98 Runoff=1.16 cfs 0.053 of
Subcatchment DA-3 Rec: Runoff Area=4.700 ac Runoff Depth>0.18"
Flow Length=370' Slope=0.0600 '/' Tc=15.1 min CN=39 Runoff=0.22 cfs 0.071 of
Reach DC-3: Avg. Depth=0.07' Max Vet=1.44 fps Inflow=0.22 cfs 0.071 of
n=0.035 L=750.0' S=0.0480 '/' Capacity=157.84 cfs Outflow=0.21 cfs 0.069 of
Pond 9P: Pump Basin Peak Elev=406.55' Storage=3,746 cf Inflow=1.16 cfs 0.122 of
Primary=0.04 cfs 0.036 of Secondary=0.00 cfs 0.000 of Outflow=0.04 cfs 0.036 of
Total Runoff Area = 4.840 ac Runoff Volume = 0.124 of Average Runoff Depth = 0.31"
97.11 % Pervious Area = 4.700 ac 2.89% Impervious Area = 0.140 ac

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 10
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 1S: Pump Basin Area
[46] Hint: Tc=O (Instant runoff peak depends on dt)
Runoff = 1.16 cfs @ 11.89 hrs, Volume= 0.053 af, Depth> 4.52"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10 YR 24 HR Rainfall=5.17"
Area (ac) CN Description
0.140 98 Paved parking & roofs
0.140 Impervious Area
Subcatchment 1S: Pump Basin Area
Hydrograph
', ' ' ', ', ❑Runoff
1.16 cfs
Type II 24-hr 10 YR 24 HR
1 Rainfall=5.17"
Runoff Area=0.140 ac
Runoff Volume=0.053 of
Runoff Depth',>4.52"
Tc=0.0 min
U-
CN=98
rj
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 11
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-3 Rec:
Runoff = 0.22 cfs @ 12.44 hrs, Volume= 0.071 af, Depth> 0.18"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10 YR 24 HR Rainfall=5.17"
Area (ac) CN Description
4.700 39 >75% Grass cover, Good, HSG A
4.700 Pervious Area
Tc Length
Slope
Velocity Capacity
Description
(min) (feet)
(ft/ft)
(ft/sec) (cfs)
14.4 300
0.0600
0.35
Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
0.7 70
0.0600
1.71
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fDs
15.1 370 Total
■ Runoff

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 12
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-3:
Inflow Area = 4.700 ac, Inflow Depth > 0.18" for 10 YR 24 HR event
Inflow = 0.22 cfs @ 12.44 hrs, Volume= 0.071 of
Outflow = 0.21 cfs @ 12.70 hrs, Volume= 0.069 af, Atten= 4%, Lag= 15.5 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 1.44 fps, Min. Travel Time= 8.7 min
Avg. Velocity = 1.11 fps, Avg. Travel Time= 11.3 min
Peak Storage= 109 cf @ 12.55 hrs, Average Depth at Peak Storage= 0.07'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 157.84 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.0 7' Top Width= 14.00'
Length= 750.0' Slope= 0.0480 7'
Inlet Invert= 442.00', Outlet Invert= 406.00'
Reach DC-3:
Hydrograph
0 Inflow
0.24 0.22 cfs ■Outflow
0.22 0.21 ifs Inf�rDW'Area=4.7
- 00 ac
0.2
Avg. Depth=0.07'
018 Max Vet=1.44 fps
0.16
0.14 n=0.035
a 0.12 L=750.0'
G
a 0.1
0.08 - - - Capacity=15 .
0.06
0.04
0.02 ----
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 11 24-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 13
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 9P: Pump Basin
[82] Warning: Early inflow requires earlier time span
[61] Hint: Submerged 2% of Reach DC-3 bottom
Inflow Area = 4.840 ac, Inflow Depth > 0.30" for 10 YR 24 HR event
Inflow = 1.16 cfs @ 11.89 hrs, Volume= 0.122 of
Outflow = 0.04 cfs @ 11.55 hrs, Volume= 0.036 af, Atten= 97%, Lag= 0.0 min
Primary = 0.04 cfs @ 11.55 hrs, Volume= 0.036 of
Secondary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 406.55' @ 20.00 hrs Surf.Area= 2,268 sf Storage= 3,746 cf
Plug -Flow detention time= 196.0 min calculated for 0.036 of (29% of inflow)
Center -of -Mass det. time= 11.6 min ( 853.4 - 841.8 )
Volume Invert Avail.Storage Storage Description
#1 404.00' 16,314 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
404.00 750 0 0
406.00 1,868 2,618 2,618
408.00 3,336 5,204 7,822
410.00 5,156 8,492 16,314
Device Routing Invert Outlet Devices
#1 Primary 404.00' 18.0" x 50.0' long Culvert CPP, mitered to conform to fill, Ke= 0.700
Outlet Invert= 403.00' S= 0.0200 7' Cc= 0.900
n= 0.020 Corrugated PE, corrugated interior
#2 Device 1 404.10' Special & User -Defined
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 0.038 0.038 0.038 0.038
#3 Device 1 408.00' 24.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600
#4 Secondary 409.00' 20.0' long x 10.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=0.04 cfs @ 11.55 hrs HW=404.21' (Free Discharge)
L1=Culvert (Passes 0.04 cfs of 0.21 cfs potential flow)
t2=Special & User -Defined (Custom Controls 0.04 cfs)
3=Orifice/Grate
( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=404.00' (Free Discharge)
t-4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 14
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
a
Pond 9P: Pump Basin
Hydrograph
1.16 CfS LEInflow
flow
Inflow'Area=4.840 ec aryondary
Peak
Elev=406.5'5'
Storage :3,746 d
0.04 cfs

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 15
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pump Basin Area Runoff Area=0.140 ac Runoff Depth>5.37"
Tc=0.0 min CN=98 Runoff=1.37 cfs 0.063 of
Subcatchment DA-3 Rec: Runoff Area=4.700 ac Runoff Depth>0.39"
Flow Length=370' Slope=0.0600 '/' Tc=15.1 min CN=39 Runoff=1.11 cfs 0.153 of
Reach DC-3: Avg. Depth=0.16' Max Vet=2.41 fps Inflow=1.11 cfs 0.153 of
n=0.035 L=750.0' S=0.0480 '/' Capacity=157.84 cfs Outflow=0.96 cfs 0.150 of
Pond 9P: Pump Basin Peak Elev=407.94' Storage=7,635 cf Inflow=1.37 cfs 0.213 of
Primary=0.04 cfs 0.037 of Secondary=0.00 cfs 0.000 of Outflow=0.04 cfs 0.037 of
Total Runoff Area = 4.840 ac Runoff Volume = 0.215 of Average Runoff Depth = 0.53"
97.11 % Pervious Area = 4.700 ac 2.89% Impervious Area = 0.140 ac

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6.11 "
Prepared by {enter your company name here} Page 16
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment 1S: Pump Basin Area
[46] Hint: Tc=O (Instant runoff peak depends on dt)
Runoff = 1.37 cfs @ 11.89 hrs, Volume= 0.063 af, Depth> 5.37"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25 YR 24 HR Rainfall=6.11"
Area (ac) CN Description
0.140 98 Paved parking & roofs
0.140 Impervious Area
Subcatchment 1S: Pump Basin Area
Hydrograph
❑ Runoff
1.37 cfs
Type 11 24-h r 25 YR 24 HR
Rainfall=6.11"
Runoff Area=0.140 ac
1 Runoff Volume=0.063 of
Runoff Depth',>5.37"
Tc=0.0 min
U-
CN=98
rj
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 17
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA-3 Rec:
Runoff = 1.11 cfs @ 12.15 hrs, Volume= 0.153 af, Depth> 0.39"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25 YR 24 HR Rainfall=6.11"
Area (ac) CN Description
4.700
39 >75% Grass cover, Good, HSG A
4.700
Pervious
Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
14.4 300
0.0600
0.35
Sheet Flow,
Grass: Short n= 0.150 P2= 3.57"
0.7 70
0.0600
1.71
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
15.1 370 Total
w
0
LL
1
0
Subcatchment DA-3 Rec:
Hydrograph
1.11 cfs
Type 1124-hr 25 YR' 24 HR
Rainfall=6.11"
Runoff Area=4.700 ac
Runoff Volume=0.153 of
Runoff Depth>0.39"
Flow Length=370'
Slope=0.0600 T
Tc=15.1 min
CN=39
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Runoff

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 18
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach DC-3:
Inflow Area = 4.700 ac, Inflow Depth > 0.39" for 25 YR 24 HR event
Inflow = 1.11 cfs @ 12.15 hrs, Volume= 0.153 of
Outflow = 0.96 cfs @ 12.32 hrs, Volume= 0.150 af, Atten= 14%, Lag= 9.9 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 2.41 fps, Min. Travel Time= 5.2 min
Avg. Velocity = 1.41 fps, Avg. Travel Time= 8.8 min
Peak Storage= 301 cf @ 12.22 hrs, Average Depth at Peak Storage= 0.16'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 157.84 cfs
2.00' x 2.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.07' Top Width= 14.00'
Length= 750.0' Slope= 0.0480 '/'
Inlet Invert= 442.00', Outlet Invert= 406.00'
3
0
LL
0
Reach DC-3:
Hydrograph
1.11 cfs
0.96 cfs
Inflow Area=4.700 ac
Avg. Depth=0.16'
Max Vet=2.41 fps
n=0.035
L=750.0'
S=0.0480 T
��qpacity=l 57.84 cfs
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Inflow
❑ Outflow

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 19
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Pond 9P: Pump Basin
[82] Warning: Early inflow requires earlier time span
[61] Hint: Submerged 5% of Reach DC-3 bottom
Inflow Area = 4.840 ac, Inflow Depth > 0.53" for 25 YR 24 HR event
Inflow = 1.37 cfs @ 11.89 hrs, Volume= 0.213 of
Outflow = 0.04 cfs @ 11.35 hrs, Volume= 0.037 af, Atten= 97%, Lag= 0.0 min
Primary = 0.04 cfs @ 11.35 hrs, Volume= 0.037 of
Secondary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 407.94' @ 20.00 hrs Surf.Area= 3,295 sf Storage= 7,635 cf
Plug -Flow detention time= 191.0 min calculated for 0.037 of (18% of inflow)
Center -of -Mass det. time= (not calculated: outflow precedes inflow)
Volume Invert Avail.Storage Storage Description
#1 404.00' 16,314 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
404.00 750 0 0
406.00 1,868 2,618 2,618
408.00 3,336 5,204 7,822
410.00 5,156 8,492 16,314
Device Routing Invert Outlet Devices
#1 Primary 404.00' 18.0" x 50.0' long Culvert CPP, mitered to conform to fill, Ke= 0.700
Outlet Invert= 403.00' S= 0.02007' Cc= 0.900
n= 0.020 Corrugated PE, corrugated interior
#2 Device 1 404.10' Special & User -Defined
Head (feet) 0.00 0.01 0.10 1.00 10.00
Disch. (cfs) 0.000 0.038 0.038 0.038 0.038
#3 Device 1 408.00' 24.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600
#4 Secondary 409.00' 20.0' long x 10.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=0.04 cfs @ 11.35 hrs HW=404.20' (Free Discharge)
L1=Culvert (Passes 0.04 cfs of 0.19 cfs potential flow)
t2=Special & User -Defined (Custom Controls 0.04 cfs)
3=Orifice/Grate
( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=404.00' (Free Discharge)
t-4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Pump Basin (Post Mine Reclamation)
Merrits Gravel Pit - Basin Type 1124-hr 25 YR 24 HR Rainfall=6. I I "
Prepared by {enter your company name here} Page 20
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
a
Pond 9P: Pump Basin
Hydrograph
1.37 cfs LEInflow
flow
Inflow'Area=4.840 ec aryondary
Peak Elev=407.9'4'
ge-7 635 Stora � , , cf
U.U4
0.04 cfs
���J/////////////////////////////////////////////////////////////////////%

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
DA) � TD
Max Drainage Area
Subca Reach and Link

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Temporary Diversion Calculation
Merrits Gravel Pit - Basin
Prepared by {enter your company name here} Page 2
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Area Listing (selected nodes)
Area (acres) CN Description (subcats)
4.000 61 >75% Grass cover, Good, HSG B (DA)
4.000

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Temporary Diversion Calculation
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 3
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment DA: Max Drainage Area Runoff Area=4.000 ac Runoff Depth>0.53"
Tc=5.0 min CN=61 Runoff=3.78 cfs 0.176 of
Reach TD: Avg. Depth=0.32' Max Vet=6.05 fps Inflow=3.78 cfs 0.176 of
n=0.022 L=560.0' S=0.0964 '/' Capacity=495.56 cfs Outflow=3.36 cfs 0.175 of
Total Runoff Area = 4.000 ac Runoff Volume = 0.176 of Average Runoff Depth = 0.53"
100.00% Pervious Area = 4.000 ac 0.00% Impervious Area = 0.000 ac

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Temporary Diversion Calculation
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 4
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA: Max Drainage Area
[49] Hint: Tc<2dt may require smaller dt
Runoff = 3.78 cfs @ 11.98 hrs, Volume= 0.176 af, Depth> 0.53"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 2 YR 24 HR Rainfall=3.57"
Area (ac) CN Description
4.000 61 >75% Grass cover, Good, HSG B
4.000 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment DA: Max Drainage Area
Hydrograph
4 ❑Runoff
3.78 cfs
Type 11 24-h r 2 YR 24 HR
Rainfall=3.57"
3 R ff A -4 000
c 2
I
LL
1
uno rea- ac
Runoff Volume=0.176 of
Runoff Depth>0.53"
Tc=5.0 min
CN=61
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Temporary Diversion Calculation
Merrits Gravel Pit - Basin Type 1124-hr 2 YR 24 HR Rainfall=3.57"
Prepared by {enter your company name here} Page 5
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach TD:
Inflow Area = 4.000 ac, Inflow Depth > 0.53" for 2 YR 24 HR event
Inflow = 3.78 cfs @ 11.98 hrs, Volume= 0.176 of
Outflow = 3.36 cfs @ 12.03 hrs, Volume= 0.175 af, Atten= 11 %, Lag= 2.8 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 6.05 fps, Min. Travel Time= 1.5 min
Avg. Velocity = 2.87 fps, Avg. Travel Time= 3.2 min
Peak Storage= 338 cf @ 12.00 hrs, Average Depth at Peak Storage= 0.32'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 495.56 cfs
0.00' x 2.00' deep channel, n= 0.022 Earth, clean & straight
Side Slope Z-value= 10.0 2.0 7' Top Width= 24.00'
Length= 560.0' Slope= 0.0964 7'
Inlet Invert= 496.00', Outlet Invert= 442.00'
4
3
c 2
LL
0
01' 5
Reach TD:
Hydrograph
❑ Inflow
3.78 cfs ❑ outflow
Inflow Area=4.000 ac
3.36 cfs Avg. Depth=0.32'
Max Vet=6.05 fps
n=0.022
L=560.0'
S=0.0964 '/'
Capacity=495.56 cfs
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Temporary Diversion Calculation
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 6
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment DA: Max Drainage Area Runoff Area=4.000 ac Runoff Depth>1.32"
Tc=5.0 min CN=61 Runoff=10.32 cfs 0.440 of
Reach TD: Avg. Depth=0.47' Max Vet=7.78 fps Inflow=10.32 cfs 0.440 of
n=0.022 L=560.0' S=0.0964 '/' Capacity=495.56 cfs Outflow=9.64 cfs 0.439 of
Total Runoff Area = 4.000 ac Runoff Volume = 0.440 of Average Runoff Depth = 1.32"
100.00% Pervious Area = 4.000 ac 0.00% Impervious Area = 0.000 ac

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Temporary Diversion Calculation
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 7
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Subcatchment DA: Max Drainage Area
[49] Hint: Tc<2dt may require smaller dt
Runoff = 10.32 cfs @ 11.97 hrs, Volume= 0.440 af, Depth> 1.32"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10 YR 24 HR Rainfall=5.17"
Area (ac) CN Description
4.000 61 >75% Grass cover, Good, HSG B
4.000 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment DA: Max Drainage Area
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Temporary Diversion Calculation
Merrits Gravel Pit - Basin Type 1124-hr 10 YR 24 HR Rainfall=5.17"
Prepared by {enter your company name here} Page 8
HydroCADO 8.00 s/n 004004 © 2006 HydroCAD Software Solutions LLC 10/28/2021
Reach TD:
Inflow Area = 4.000 ac, Inflow Depth > 1.32" for 10 YR 24 HR event
Inflow = 10.32 cfs @ 11.97 hrs, Volume= 0.440 of
Outflow = 9.64 cfs @ 12.00 hrs, Volume= 0.439 af, Atten= 7%, Lag= 2.1 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 7.78 fps, Min. Travel Time= 1.2 min
Avg. Velocity = 3.42 fps, Avg. Travel Time= 2.7 min
Peak Storage= 728 cf @ 11.99 hrs, Average Depth at Peak Storage= 0.47'
Bank -Full Depth= 2.00', Capacity at Bank -Full= 495.56 cfs
0.00' x 2.00' deep channel, n= 0.022 Earth, clean & straight
Side Slope Z-value= 10.0 2.07' Top Width= 24.00'
Length= 560.0' Slope= 0.0964 '/'
Inlet Invert= 496.00', Outlet Invert= 442.00'
Reach TD:
Hydrograph
10.32 cfs
11 Inflow Area=4.000 ac
10 9.64 cfs
9 Avg. Depth=0.47'
8 Max Vet=7.78 fps
7 n=0.022
3 6 L=560.0'
0
LL 5 S=0.0964 '/'
4
Capacity=495.56 cfs
3
2
1
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Inflow
❑ Outflow

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
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 10/25/2021
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 - 10-25-21

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's Gravel Pit SHEET 2 OF 6 DATE 10/25/2021
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 - 10-25-21

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
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 10/25/2021
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 - 10-25-21

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's Gravel Pit
SHEET 4 OF 6
SUBJECT Drainage Channel Analysis JOB #
MERRITT-21-1
DATE 10/25/2021
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
n
Inches
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 - 10-25-21

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's travel Pit
SHEET
5/6
JOB#
MERRITT-21-1
SUBJECT Drainage Channel Analysis (Grass Lined)
DATE
8/25/2021
COMPUTED BY
JCL
Channel No.
DC-1 -3
CHECKED BY
SAS
Design
Parameters:
PEAK DISCHARGE, Q2=
8.1
ft3/s
Source:
HydroCAD2-Yr24-Hr
PEAK DISCHARGE, 010=
24.2
ft3/s
Source:
HydroCAD25-Yr24-Hr
Bottom Width, B =
3.0
ft
Permanent (lass Lininar
Temporary Lining
Left Side Slope, z, =
3.0
horizontal :1 vertical
Grass Retardanoe
D
Temporary Lining
Used MN) =
Y
Right Side Slope, zz=
3.0
horizontal :1 vertical
K=
34.6
RECP Product Name =NA
Green- Curlex 1, or equal
1/01. =
4.5
ft/sec
Manning's Coefficient, n =
0.035
Minimum Freeboard=
0.5
ft
1-=
0.60
Ib/ft'
zwiow=
1.55 lb/ft'
Maximum Channel Slope, S,,,a, =
0.040
ft/ft
Bare Ground (If Tem op rary Liner Not
Used),
Minimum Channel Slope, S,,;,, _'
0.010
ft/ft
Manning's Coefficient, n =
0.020
1/0- =
2.0
ft/sec
Normal Depth
Depth of Fl ow
Manning's
Area
Wetted
Hydraulic
Top
Hydraulic
Average
Flow
Froude
Maximum
Allowable
Factor
(Norm. Depth)
Roughness
of Flow
Perimeter
Radius
Width
Depth
Velocity
Rate
Number
Shear Stress
Velocity M or
of Safety
Comment
Y„
Coefficient
A
P
R--AiP
T
D--AiT
V
0
F, (Norma/)
ze
Sh. Stress (S)
v-/v„ or
ft
n
ft2
ft
ft
fl
ft
ft/s
ft3/s
#
Ib/ft'
Used?
Q2
Maximum Slope:
0.45
0.035 1.96
5.85
0.33
5.70
0.34 4.10
8.0
1.23
1.1
S
1.4 O.K.
Minimum Slope:
0.65
0.035 3.22
7.11
0.45
6.90
0.47 2.51
8.1
0.65
0.4
S
3.8 O.K.
025
Maximum Slope:
0.97
0.052 5.73
9.13
0.63
8.82
0.65 4.20
24.1
0.92
2.4
V
1.1 O.K.
Minimum Slope:
1.43
0.058 10.42
12.04
0.87
11.58
0.90 2.33
24.3
0.43
0.9
V
1.9 O.K.
Critical Depth
Depth of Fl ow
Manning's
Area
Wetted
Hydraulic
Top
Hydraulic
Section
Flow
Average
Froude
Uniform -Flow
(Cril. Depth)
Roughness
of Flow
Perimeter
Radius
Width
Depth
Factor
Rate
Velocity
Number
Critical Slope
Comment
Y
Coefficient
A
P
R--AiP
T
D--AiT
Z=AD
0
V
F, (Offical)
S,
ft
n
ft,
It
ft
ft
ft
ft3/s
ft/s
#
ft/ft
02
0.51
0.035 2.31
6.23
0.37
6.06
0.38 1.43
8.1
3.50
1.00
0.025
Flow is Stable.
025
0.93
0.052 5.38
8.88
0.61
8.58
0.63 4.27
24.2
4.50
1.00
0.047
Slopes Near Sc- Check Freeboard.
Determination of Minimum Channel Depth & Top Width (Based on 025)
Maximum
Slope
Minimum
Slope
Minimum
Minimum
Minimum
Minimum
Channel
Top Width
Channel
Top Width
Depth
T
Depth
T
ft
fl
ft
fl
1.47
11.82
1.93
14.58
SMITH GARDNER, INC. Gass DRAINAGE CHANNEL- Merritt - 1 O25-21

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's travel Pit
SHEET
6/6
JOB#
MERRITT-21-1
SUBJECT Drainage Channel Analysis (Grass Lined)
DATE
10120/2021
COMPUTED BY
JCL
Channel No.
Temporary Diversion
CHECKED BY
SAS
Design
Parameters:
PEAK DISCHARGE, Q2=
3.4
ft3/s
Source:
HydroCAD 10-Yr 24-Hr
PEAK DISCHARGE, 010=
9.6
fts/s
Source:
HydroCAD 10-Yr 24-Hr
Bottom Width, B =
0.0
ft
Permanent (lass Linincr
Temporary Lining
Left Side Slope, z, =
10.0
horizontal :1 vertical
Grass Retardanoe
D
Temporary Lining
Used MN) =
Y
Right Side Slope, zz=
2.0
horizontal :1 vertical
K=
34.6
RECP Product Name
NA Green- O1rlex 1, or equal
1/01. =
4.5
ft/sec
Manning's Coefficient, n =
0.035
Minimum Freeboard=
0.3
ft
1-=
0.60
Ib/ft'
zwiow=
1.55 Ib/ft2
Maximum Channel Slope, S,,,a,=M
0.050
ft/ft
Bare Ground (If Tern op rary Liner Not
Used),
Minimum Channel Slope, S,,;,, =
0.010
ft/ft
Manning's Coefficient, n =
0.020
1/0- =
2.0
ft/sec
Normal Depth
Depth of Fl ow
Manning's
Area
Wetted
Hydraulic
Top
Hydraulic
Average
Flow
Froude
Maximum
Allowable
Factor
(Norm. Depth)
Roughness
of Flow
Perimeter
Radius
Width
Depth
Velocity
Rate
Number
Shear Stress
Velocity M or
of Safety
Comment
Y„
Coefficient
A
P
R--AiP
T
D--AiT
V
0
F, (Norma/)
ze
Sh. Stress (S)
v-/v„ or
ft
n
ft2
ft
ft
fl
ft
ft/s
fts/s
#
Ib/ft'
Used?
Q2
Maximum Slope:
0.42
0.035 1.06
5.16
0.21
5.04
0.21 3.31
3.5
1.27
1.3
S
1.2 O.K.
Minimum Slope:
0.56
0.035 1.88
6.88
0.27
6.72
0.28 1.79
3.4
0.60
0.3
S
4.4 O.K.
C25
Maximum Slope:
0.79
0.068 3.74
9.71
0.39
9.48
040 260
9.7
0.73
2.5
V
1.7 O.K.
Minimum Slope:
1.13
0.080 7.66
13.88
0.55
13.56
0.56 1.26
9.6
0.29
0.7
V
3.6 O.K.
Critical Depth
Depth of Fl ow
Manning's
Area
Wetted
Hydraulic
Top
Hydraulic
Section
Flow
Average
Froude
Uniform -Flow
(Cril. Depth)
Roughness
of Flow
Perimeter
Radius
Width
Depth
Factor
Rate
Velocity
Number
Critical Slope
Comment
Y
Coefficient
A
P
R--AiP
T
D--AiT
Z=AD
0
V
F, (Qifical)
S,
ft
n
W
It
ft
ft
ft
ft2.5
ft3/s
ft/s
#
ft/ft
C2
0.46
0.035 1.27
5.65
0.22
5.52
0.23 0.61
3.5
2.72
1.00
0.030
Flow is Stable.
025
0.69
0.064 2.86
8.48
0.34
8.28
0.35 1.68
9.5
3.33
1.00
0.087
Flow is Stable.
Determination of Minimum Channel Depth & Top Width (Based on 025)
Maximum
Slope
Minimum
Slope
Minimum
Minimum
Minimum
Minimum
Channel
Top Width
Channel
Top Width
Depth
T
Depth
T
ft
fl
ft
fl
1.09
13.08
1.43
17.16
SMITH GARDNER, INC. Grass RTCfor TD DRAINAGE CHANNEL- Merritt - 1 O2S21

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
TEL I WEB
SMITH G A R D N E R 1 14 N. Boylan Avenue, Raleiqh, NC 27603 1 919.828.0577 1 www.smithgardnerinc.com
PROJECT Merritt's Gravel pit SHEET 1 OF 16 DATE 10/25/2021
COMPUTED BY JCL
SUBJECT Sediment Basin Analysis JOB # MERRITT-21-1 CHECKED BY SAS
OBJECTIVE: To design a sediment basin(s) to satisfy erosion and sediment control requirements and to handle the flow
from the design storm.
REFERENCES: American Concrete Pipe Association (1996), "Design Data 41 - Manhole Floatation", ACPA, Irving, TX.
Malcom, H. Rooney (1989 & 2003 Supplement), Elements of Urban Stormwater Design, NC State Univ.,
Raleigh, NC.
North Carolina Division of Land Resources (2013 Updates), North Carolina Erosion & Sediment Control
Planning & Design Manual, Raleigh, NC.
Virginia Department of Conservation and Recreation (1992), Virginia Erosion & Sediment Control
Handbook, Third Edition, Richmond, VA.
ANALYSIS: The following approach is used to properly size and evaluate each sediment basin:
1. Design for Wet (If Applicable) and Dry Storage.
2. Route Design Storm.
3. Design Outlet Structures (Design Riser/Barrel Structures and Perform Riser Base Calculations,
Anti -Seepage Collar Calculations, & Emergency Spillway Calculations).
CALCULATIONS:
- Design for Wet (If Applicable) and Dry Storage:
Determine required wet (if applicable) and dry storage volumes based on applicable erosion and sedimentation
control requirements.
If applicable, calculate the desired surface area at the principal spillway. For some locations:
A = 0.01Qf,
where: A = desired surface area (acres)
C F = peak discharge from design storm (cfs)
(NC- Use 10-yr 24-hr storm; G4- Use 2-yr 24-hr storm)
Set up a stage -storage relationship for the proposed basin as shown below. Based on this relationship and the
required volume(s) and/or desired surface area, determine the required wet storage (if applicable) and dry storage
elevations. Alternatively the elevation(s) can be determined from a graphical stage -storage relationship.
S= KZ' (Malcom Eq. III-7)
where: 5 = storaqe volume (ft)
K b = linear regression constants describing the stage -storage relationship
z = stage referenced to the bottom elevation included in the analysis (ft)
Set sediment basin cleanout elevation.
SMITH GARDNER, INC. SED BASIN -GENERAL Merritts Gravel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's Gravel pit SHEET 2 OF 16
SUBJECT Sediment Basin Analysis JOB # MERRITT-21-1
DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
Size the outlet device to release the dry storage volume (WON/) over the desired drawdown period (typical ly this is a
minimum of 24 hours). Use the following equation:
As 2h (from Original Edition of NCE&SCP&DM)
A TCd(20,428)
where: A , = surface area of dewaterinq hole(s) (ft)
A s = surface area of basin (at principal spillway) (ft)
h = average head of water above hole (_ (elev. of principal spillway- elev. of wet storage
or (if not applicable) bottom of basin)/2) (ft)
C o = coefficient of contraction (=0.60)
7 = detention time (hrs.) (vary over recommended limits)
Select a standard pipe size and number of holes. Verifythat the projected drawdown period is within the
recommended limits.
Where desired, size a drain for the basin for maintenance. The drain should dewater the basin (to principal
spillway) within 24 hours. Use the above equation to determine A. of the basin drain. The inlet of the drain should
be protected from the sediment storage zone.
Evaluate basin shape. Compare with the recommended length to width ratio. If this ratio is not achieved, the basin
should be modified or baffles should be added as required.
- Route Design Storm:
Route the design storm through the basin and determine the maximum pool elevation and the peak discharge (via
HydroCAD, spreadsheet methods, or other). Depending on local requirements, multiple design storms may need
to be considered and the peak discharge may need to be compared with the pre -development value.
Based on the peak stage of the design storm, check settling efficiency of the design particle. The design particle is
typically40 microns (0.04 mm) (within silt size criteria).
Settling Velocity of Design Particle
V =
g �(S S _ 1��d2 (Malcom Eq. IV-3)
18 v J
where:
9
55 =
v =
Surface Area
settling velocity (ft/s) - convert from (m/s)
gravitational acceleration (m/s2)
specific gravity of design particle
kinematic viscosity of the fluid (m2/s)
(= 1.14 x 10-6 mz/s (a�15C- Ref. Streeter, 1975)
diameter of design particle (m)
As = WsZ(b-1) (Malcom Eq. IV-7)
where: A 5 = surface area at given stage (Z) (ft)
Ks,b = linear regression constants describing the stage -storage relationship
SMITH GARDNER
SMITH GARDNER, INC. SED BASIN -GENERAL Merritts Gravel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's Gravel pit
SUBJECT Sediment Basin Analvsis
Settling Efficiency
E=1-IVoAs I]-N
1+ NQJ
SHEET 3 OF 16
JOB# MERRITT-21-1
(Malcom Eq. IV-1)
DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
where: E = settling efficiency (decimal fraction - convert to %)
A a = surface area at given stage (Z) (ft)
N = number of effective cells (N = 2 with forebay)
G = discharge at given stage (Z) (cfs)
- Design of Outlet Structures:
Design riser/barrel structures based on information used in routing the design storm.
Design base for riser structure to resist design uplift force. Base must have a buoyant weight of at least the design
uplift force. If a concrete riser structure is used, the buoyant weight of the riser can be accounted for in the
calculations.
Design Uplift Force (tQ
T F = (FS)V, ,,-,,, — WRfser — WTop — Wsott — Rsotr (from VAE&SCH Spec. 3.14)
where: TF = design uplift force (I bs)
FS = factor of safety (use 1.25)
VRiser = interior volume of the riser (ft2) (base elevation to principal spillwayelevation)
VH2c = density of water (62.4 pcf)
WRiser buoyant weight of riser (not including base or top) (Ibs)
WToo = buoyant weight of riser top (Ibs)
Wso;i = buoyant weight of soil backfill around riser (above base projection) (Ibs)
Rso;i = sliding resistance of soil backfill around riser (Ibs)'
See American Concrete Pipe Association Design Data 41 for more information.
Volume of Concrete for Base
vco = (from VAE&SCH Spec. 3.14)
N'co �,, (150— 62.4)
where: LC C. = volume of concrete (ft)
W Coic6 = buoyant weight of concrete (150 - 62.4 = 87.61 bs)
Anti -Seepage Col lar(s)
Determine anti -seepage collar requirements based on the following equation. Alternatively, a filter
diaphragm maybe designed.
LS = i (z + 4)1
1 + 0.25 — s� IJ (VA E&SC Handbook p. 111-102)
where: L, = length of pipe in the saturated zone (ft)
y = distance from barrel invert to riser crest (ft)
2 = slope of upstream embankment (zHAV)
s = pipe slope (ft/ft)
SMITH GARDNER
SMITH GARNER, INC. SED BASIN -GENERAL Merritts Gravel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's Gravel pit SHEET 4 OF 16
SUBJECT Sediment Basin Analysis JOB # MERRITT-21-1
DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
Determine Ls and use design chart to determine anti -seepage collar requirements. If more than one col lar is used,
the spacing between collars should be 14 times the projection (P) of the collar above the barrel. The first collar
should beset at 2P from the riser or a minimum length to bury collar in slope.
Emergency Spillway
Design crest length of emergency spillway to handle flow from the design storm using the following equation.
Determine peak flow from stormwater routing program. If applicable, design outlet channel as a drainage channel
or rock chute.
Qr = CIILH312 (Malcom Eq. 1-6)
where: C F = peak discharge from design storm (cfs)
C w = weir coefficient (=3.0 for free overfal I )
L = length of weir (ft)
h = driving head (ft) (=allowable headwater above crest of weir or calculated
value from stormwater routing program)
SMITH GARDNER
SMITH GARDNER, INC. SED BASIN -GENERAL Merritts Gravel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt', travel pit SHEET 5/16
JOB# MERRITT-21-1
SUBJECT Sediment Basin Analysis DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
Basin No.: -adiment Basin 1
DESIGN FOR WET (IF APPLICABLE) AND DRYSTCRAGE:
Areas Draining Into Basin:
Area
Drainage Area (acres)
Drainage Area 1 18.1
Total = 18.1 Acres
Basin Requirements:
Wet Storaae,
Required Storage Capacity ((('/Ac.) 0Enter "I if Not Applicable.
Required Storage Capacity (ft')= 0
Required Depth of Wet Storage (ft) = 0.0 Enter "I if Not Appl!-his.
Dry Storage,
Required Storage Capacity ((('/Ac.) 1,800 To Crest of Principal Spillway
Required Storage Capacity (ft')= 32,580
Multipier (X) for Desired Surface Area (Op x X) 0.01 Al (rest of Principal Spillway
Peak Discharge l nto Basin (Cp)(cfs)=� 34.9 From HydroCAD-10-Yr, 24-Hr. Storm
Desired Surface Area(Ac)= 0.35
Desired Surface Area (ft')= 15,202
Determine Staae-Slorage Function:
Contour
Area
Area
Incremental
Olmuladye
Stage
In S
In Z
Zest
(ft2)
(acres)
Vol uma(ft)
Volume (ft')
(ft)
396
5,700
0.13
0
0.0
400
8,500
0.20
28,400
28,400
4.0
10.25
1.39
4.09
402
10,200
0.23
18,700
47,100
6.0
10.76
1.79
5.89
404
12,300
0.28
22,500
69,600
8.0
11.15
2.08
7.79
406
15,700
0.36
28,000
97,600
10.0
11.49
2.30
9.92
408
19,400
0.45
35,100
132,700
12.0
11.80
2.48
12.37
Linear
Regression
Constants:
Ks=
3,978
Storage = 3978 e 1.39
b=
139
'CAUTION: CHECK
INPUT FOR REGRESSION ANALYSIS!
Stage -Surface Area Relationship
410
408
406
404
402
400
398
396
394
0 5,000 10,000 15,000 20,000 25,000
Surface Area (sn
410
408
406
404
402
H 401
398
396
394
Stage -Storage Relationship
0 50,000 100,000 150,000
storage (cf)
SMITH GARDNER
SMITH GARDNER, ING S im Basin SEED BASIN -GENERAL Merrill.&-H Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's travel pit
SUBJECT Sediment Basin Analysis
Basin Design Elevations,
Bay. of Bottom of Basin (ft) = 396.0
Wet Storage,
Required Storage Capacity (ft')= 0
Min. Elev. of Wet Storage (Permanent Pool)= 396.0
Selected Elev. of Wet Storage (Permanent Pool) = 396.0 OK.
Actual Wet Storage Volume(ft')= 0 OK.
Dry Storage
Required Storage Capacity (fl) _
Min. Bev. of Principal Spillway(ft)=
Selected Bev. of Principal Spillway(ft)=
Actual Total Storage Volume (ft) _
Desired Surface Area (ft) _
Actual Surface Area at Principal Spillway (ft) _
aeanoul:
Cleanoul Requirement (%of Wet Storage)=
Geanout Requirement (%of Total Storage)=
Basin Cleanoul Volume (fl) _
Basin Geanout Elevation (ft)=
DewAtiring of Dry Storage,
Basin Shape•
Option, Faircloth Skimmer
Actual Total Storage Volume to Dewater (ft) _
Required Orifice Diameter (in)_
32,580 =Required Dry Storage + Actual Wet Storage
400.5
406.0 O.K.
98,637 O.K.
15,202
13,753 No Good. Increase SurfaceArea at Permanent Pool If Possible.
0 Enter "0" if Not Applicable
0 Based on %of Total Storage Volume
3960
98,637 =Volume at Principal Spillway
4.0 From www.fsirclothskimmer.com Based on 2 to 5 Day Drawdown
Length of Basin (ft)= 180 Measured at Principal Spillway Elevation
Width of Basin (ft)= 140 Measured at Principal Spillway Elevation
Desired Length to Width Ratio (X1)= 2
Actual Length to Width Ratio (X1) = 1.3 No Good. Revise Shape or Add Baffles.
SHEET 6/16
JOB# MERRITF-21-1
DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
SMITH GARDNER
SMITH GARDNER, ING S i-3win SED BASIN -GENERAL Merrilts Gavel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt', travel pit SHEET 7/16
JOB# MERRITT-21-1
SUBJECT Sediment Basin Analysis DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
ROUTE DESIGN STORM: Use HydroCAD or Other Method.
Design Parameters,
Design Storm: 10-Yr, 24-Hr
Design Storm Rainfall (in)= 5.17
Rainfall Distribution: Type II
Runoff Method: SCSTR-20
Results:
Maximum Pool Elevation = 406.7
Surface Area at Maximum Pool (ft')= 14,125
Peak Discharge (cfs) = 1.1
Check Setti ing Efficiency
Particle Data:
Diam.(microns)=
40
Specific Gravity=
2.65
Settl ing Val oc.(ft/s)=
0.004140
Reynolds No. (W.5)=
0.044284 OK.
Efficiency Data,
Desired Efficiency (%) =
80
No. of Effective Cells =
3
Settling Efficiency (%) =
100.0 O.K.
DESIGN OUTLETSTRUCTURES•
Design Riser/Barrel Structures,
Riser Desicm
Type of Riser: HOPE - Circular
Top of Riser Base Elevation (ft) = 398.0
Elev. of Principal Spillway (ft)= 406.0
Riser Top Elevation (ft)= 406.0
Riser Height (ft) = 8.0
Outlets:
Outlet No. 1 (for Dewatering Dry Storage): Si— 4" Diam. For Skimmer From Above- Dewatering of Dry Storage
Invert Elevation: 396.1 May Vary For Multiple Holes
Outlet No. 2 (Principal Spillway): Si— 36" dia. CPP
Invert Elevation: 406.0
Riser Inside Diameter(ft)= 3.0
Approx. arc. Riser Interior Volume (cf)= 57
Barrel Design,
Type of Barrel:
HOPE
Diameter (in) =
24
Inv. In Elevation (ft)=
396.0
Inv. Out Elevation (ft)=
395.0
Length (ft)=
110.0
Slope (ft/ft) =
0.009
(Top of Base to Principal Spillway)
SMITH GARDNER
SMITH GARDNER, ING S,ximent B.in SED BASIN-CFNPRAL Merritt, Gravel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt', travel pit SHEET 8/16
JOB# MERRITT-21-1
SUBJECT Sediment Basin Analysis DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
Poser Base Calculations,
Design Uplift Force
Factor of Safety=
F (unadjusted) (Ibs) _
HDPE Riser Buoyant Weight (Ibs) _
Buoyant WI. of Riser Top (Ibs)=
Buoyant Wt. of Surrounding Soil Acting on Ext. Base (Ibs) _
Sliding Resistance of Surrounding Soil (Ibs) _
F (adjusted) (Ibs)=
Concrete Base:
Required Volume of Concrete (ft') _
Length (ft) _
Width (ft)=
Thickness (ft) _
Actual Volume of Concrete (ft') _
Anti -Seepage Collar Calculations: (Alternatively- Design Flltar Diaphragm)
Slope of Upstream Embankment (zHA V) =
Slope of Outlet Pipe (ft/ft) _
L. (ft) _
Number of ON lars:
Length of Each Collar (ft) _
Width of Each Col lar (ft) _
Collar Projection, P(ft)=
Sped ng of Subsequent Anti -Seep Collars (ft) _
Emergency Spillway Calculations,
SUMMARYDATA:
Crest Elev. (ft)=
Required Freeboard (ft)=
Top of Bar m El ev. (ft) _
Required Capacity (cfs) _
(hiving Head (ft)=
Weir Coefficient =
Length of Crest (ft) _
Design Crest Length (ft) _
1.25
4,411
0
0
0
0
0
0
0
4,411
50.4
7.5
7.5
1.0 (Includes Concrete III Inside of Box)
56.3 OK.
3
0.009
58
3
5.0 From Design Chart Based on L. and No. of Collars
5.0 From Design Chart Based on L. and No. of Collars
1.5
21 =14P
407.0
1.0
408.0
20.0 From HydroCAD- No Outflow from 11124-Hr. Storm; Assume 20 cis Capacity
0.5 Assumed
3.0
18.9 Determine by Weir Equation"
20
Length =20 ft minimum.
Basin No.: Sediment Basin t
Bev. of Bottom of Basin (ft) =
396.0
Cl eanout FJ ev.(ft)=
396.0
Elev. of Wet Storage (Permanent Pool) (ft)=
NA
Elev. of Principal Spillway (ft)=
406.0 See Abovefor Riser and Other Design Information.
Emergency Spillway Elev.(ft)=
407.0
Top of Bar m El ev.(ft)=
408.0
Topof Berm Wdth(ft)=_
10
Barrel Diameter (in)=
24
Barrel Slope(%)=
0.9
SMITH GARDNER
SMITH GARDNER, ING S im 3win SEED BASIN-CFNER Merritt, Qavel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's travel pit
SUBJECT Sediment Basin Analysis
SHEET
JOB#
DATE
COMPUTED BY
CHECKED BY
9/16
MERRITT-21-1
10/25/2021
JCL
SAS
Basin No.: -amp Basin (Mine
DESIGN FOR WET (IF APPLICABLE) AND DRYSTCRAGE:
Areas Draining Into Basin:
Area
Drainage Area
(acres)
Drainage Area
0.8
Excavated Pond Area (Approx.)
11.0
Total = 0.8 Acres "Draining naturally into basin
Basin Requirements:
Wet Store=
Required Storage Capacity (ft'/Ac.)
0Enter "I if Not Appl !cable.
Required Storage Capacity(([')=
0
Required Depth of Wet Storage (ft) =
0.0 Enter "I if Not Appl!-his.
Dry Storage,
Required Storage Capacity ((('/Ac.)
1,800 To Crest of Principal Spillway
Required Storage Capacity(([')=
1,440
Multipier
(X) for Desired Surface Area (OP x X)
0.01 Al (rest of Principal Spillway
Peak Discharge into Basin (Op)(cfs)=� 7.6 From HI-10-Yr, 24-Hr. Storm
Desired Surface Area(Ac)=
0.08
Desired Surface Area (ft')=
3,289
Determine Stage -Storage Function:
Contour
Area Area
Incremental GLmulabve Stage
(ft') (acres)
Volume (ft) Volume (ft') (ft)
404
900 0.02
0 0.0
406
2,100 0.05
3,000 3,000 2.0
408
3,700 0.08
5,800 8,800 4.0
410
5,900 0.14
9,600 18,400 6.0
Linear Regression Constants:
Ks= 947
Storage =947 zA 1.64
b = 1 64
'CAUTION: CHECK INPUT FOR REGRESSION ANALYSIS!
Stage -Surface Area Relationship
411
410
409
408
407
406
405
404
403
0 1,000 2,000 3,000 4,000 5,000 6,000 7,000
Surface Area (sn
*Including max pump discharge
Ins
InZ
Zest
8.01
0.69
2.02
9.08
1.39
3.89
9.82
1.79
6.10
Stage -Storage Relationship
411
410
409
408
407
406 FF
405
404
403
0 5,000 10,000 15,000 20,000
Storage (cf(
SMITH GARDNER
SMITH GARDNER, ING Pump Basin SEED BASIN -GENERAL Merrill.&a HPit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's travel pit
SUBJECT Sediment Basin Analysis
Basin Design Elevations,
Bay. of Bottom of Basin (ft) = 404.0
Wet Storage,
Required Storage Capacity (ft')= 0
Min. Elev. of Wet Storage (Permanent Pool)= 404.0
Selected Elev. of Wet Storage (Permanent Pool) = 404.0 OK.
Actual Wet Storage Volume(ft')= 0 OK.
Dry Storage
Required Storage Capacity (ft') _
Min. Bev. of Principal Spillway(ft)=
Selected Bev. of Principal Spillway(ft)=
Actual Total Storage Volume (ft) _
Desired Surface Area (ft) _
Actual Surface Area at Principal Spillway (ft) _
aeanoul:
Cleanoul Requirement (%of Wet Storage)=
Geanout Requirement (%of Total Storage)=
Basin Cleanoul Volume (ft') _
Basin Geanout Elevation (ft)=
DewAtiring of Dry Storage,
Basin Shane
Option, Faircloth Skimmer
Actual Total Storage Volume to Dewater (ft') _
Required Orifice Diameter (in)_
1,440 =Required Dry Storage + Actual Wet Storage
405.3
408.0 O.K.
9,200 O.K.
3,289
3,773 O.K.
0 Enter "0" if Not Applicable
0 Based on %of Total Storage Volume
4040
9,200 =Volume at Principal Spillway
2.0 From www.fairclothskimmer.com Based on 2 to 5 Day Drawdown
Length of Basin (ft)= 150 Measured at Principal Spillway Elevation
Width of Basin (ft)= 50 Measured at Principal Spillway Elevation
Desired Length to Width Ratio (X1)= 2
Actual Length to Width Ratio (X1) = 3.0 O.K.
SHEET 10/16
JOB# MERRITF-21-1
DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
SMITH GARDNER
SMITH GARDNER, ING Pump Basin SED BASIN-CFNF Merrilts Gavel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt', travel pit SHEET 11/16
JOB# MERRITT-21-1
SUBJECT Sediment Basin Analysis DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
ROUTE DESIGN STORM: Use HydroCAD or Other Method.
Design Parameters,
Design Storm: 10-Yr, 24-Hr
Design Storm Rainfall (in)= 5.17
Rainfall Distribution: Type II
Runoff Method: SCSTR-20
Results:
Maximum Pool Elevation = 408.5
Surface Area at Maximum Pool (ft')= 4,063
Peak Discharge (cfs) = 7.1
Check Setti ing Efficiency
Particle Data:
Diam.(microns)=
40
Specific Gravity=
2.65
Settl ing Val oc.(ft/s)=
0.004140
Reynolds No. (W.5)=
0.044284 OK.
Efficiency Data,
Desired Efficiency (%) =
80
No. of Effective Cells =
3
Settling Efficiency (%) =
82.6 OK.
DESIGN OUTLETSTRUCTURES•
Design Riser/Barrel Structures,
Riser Desicm
Type of Riser: CAMP - Circular
Top of Riser Base Elevation (ft) = 398.0
Elev. of Principal Spillway (ft)= 408.0
Riser Top Elevation (ft)= 404.0
Riser Height (ft) = 6.0
Outlets:
Outlet No. 1 (for Dewatering Dry Storage): Si— 2" Diam. For Skimmer From Above- Dewatering of Dry Storage
Invert Elevation: 398.1 May Vary For Multiple Holes
Outlet No. 2 (Principal Spillway): Si— 24' dia. CPP
Invert Elevation: 408.0
Riser Inside Diameter(ft)= 2.0
Approx. arc. Riser Interior Volume (cf)= 31
Barrel Design,
Type of Barrel:
HOPE
Diameter (in) =
18
Inv. In Elevation (ft)=
404.0
Inv. Out Elevation (ft)=
403.0
Length (ft)=
50.0
Slope (ft/ft) =
0.020
(Top of Base to Principal Spillway)
SMITH GARDNER
SMITH GARDNER, ING Pump Basin SED BASIN-CFNPRAL Merritt, Gravel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt', travel pit SHEET 12MET
JOB# MERRITT-21-1
SUBJECT Sediment Basin Analysis DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
Poser Base Calculations,
Design Uplift Force
Factor of Safety=
F (unadjusted) (Ibs) _
CMP Riser Buoyant Weight (Ibs) _
Buoyant VA. of Riser Top (Ibs)=
Buoyant Wt. of Surrounding Soil Acting on Ext. Base (Ibs) _
Sliding Resistance of Surrounding Soil (Ibs) _
F (adjusted) (Ibs)=
Concrete Base:
Required Volume of Concrete (ft') _
Length (ft) _
Width (ft)=
Thickness (ft) _
Actual Volume of Concrete (ft') _
Anti -Seepage Collar Calculations: (Alternatively- Design Flltar Diaphragm)
Slope of Upstream Embankment (zHA V) =
Slope of Outlet Pipe (ft/ft) _
L. (ft) _
Number of Collars:
Length of Each Collar (ft) _
Width of Each Collar (ft) _
Collar Projection, P(ft)=
Spacing of Subsequent Anti -Seep Collars (ft) _
Emergency Spillway Calculations•
SUMMARYDATA:
Crest Elev. (ft)=
Required Freeboard (ft)=
Top of Bar m El ev. (ft) _
Required Capacity (cfs) _
(hiving Head (ft)=
Weir Coefficient =
Length of Crest (ft) _
Design Crest Length (ft) _
1.25
2,450
0
0
0
0
0
0
0
2,450
28.0
6.0
6.0
1.0 (Includes Concrete III Inside of Box)
36.0 OK.
3
0.020
46
2
5.5 From Design Chart Based on L. and No. of Collars
5.5 From Design Chart Based on L. and No. of Collars
2
28 =14P
407.0
1.0
408.0
20.0 From HydroCAD- No Outflow from 11124-Hr. Storm; Assume 20 cis Capacity
0.5 Assumed
3.0
18.9 Determine by Weir Equation"
20
Length =20 ft minimum.
Basin No.: Pump Basin (Mine Operations)
Bev. of Bottom of Basin (ft) =
404.0
Cl eanout FJ ev.(ft)=
404.0
Elev. of Wet Storage (Permanent Pool) (ft)=
NA
Elev. of Principal Spillway (ft)=
408.0 See Above for Riser and Other Design Information.
Emergency Spillway Elev.(ft)=
407.0
Top of Bar m El ev.(ft)=
408.0
Top of Berm Wdth(ft)=_
10
Barrel Diameter (in)=
18
Barrel Slope(%)=
2.0
SMITH GARDNER
SMITH GARDNER, ING Pump B.in SEED BASIN -GENERAL Merritt, Qavel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's travel pit
SUBJECT Sediment Basin Analysis
SHEET
JOB#
DATE
COMPUTED BY
CHECKED BY
13/16
MERRITT-21-1
10/25/2021
JCL
SAS
Basin No.: Wmp Basin (Post-Rac)
DESIGN FOR WET (IF APPLICABLE) AND DRYSTCRAGE
Areas Draining Into Basin:
Area
Drainage Area
(acres)
Drainage Area
4.7
Total =
4.7 Acres
Basin Requirements:
Wet Storage,
Required Storage Capacity ((('/Ac.)
0Enter "I if Not Applicable.
Required Storage Capacity (ft')=
0
Required Depth of Wet Storage (ft) =
0.0 Enter "I if Not Appl!-his.
Dry Storage,
Required Storage Capacity ((('/Ac.)
1,800 To Crest of Principal Spillway
Required Storage Capacity (ft')=
8,460
Multipier (X) for Desired Surface Area (OP x X)
0.01 Al (rest of Principal Spillway
Peak Discharge into Basin (Cp)(cfs)=� 1.2 From HydroCAD-10-Yr, 24-Hr. Storm
Desired Surface Area(Ac)=
0.01
Desired Surface Area (ft')=
523
Determine Staae-Slorage Function:
Contour Area Area
Incremental Olmulffi!ye Stage
InS
InZ
Zest
(ft2) (acres)
Volume(ft') Volume (it') (ft)
404 900 0.02
0 0.0
406 2,100 0.05
3,000 3,000 2.0
8.01
0.69
2.02
408 3,700 0.08
5,800 8,800 4.0
9.08
1.39
3.89
410 5,900 0.14
9,600 18,400 6.0
9.82
1.79
6.10
Linear Regression Constants,
Ks= 947
Storage=947 zA 1.64
b = 1 64
'CAUTION: CHECK INPUT FOR REGRESSION ANALYSIS!
Stage -Surface Area Relationship
Stage -Storage Relationship
411
411
410
410
409
409
408
408
407
407
KH-
406
406
405
405
404
404
403
403
0 1,000 2,000 3,000 4,000
5,000 6,000 7,000 0
5,000 10,000
15,000 20,000
Surface Area (sf)
Storage (cf(
SMITH GARDNER
SMITH GARDNER, ING Pump Basin (reclamation) S [)BASIN -GENERAL Merrill.&—H Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's travel pit
SUBJECT Sediment Basin Analysis
Basin Design Elevations,
Bay. of Bottom of Basin (ft) = 404.0
Wet Storage,
Required Storage Capacity (ft')= 0
Min. Elev. of Wet Storage (Permanent Pool)= 404.0
Selected Elev. of Wet Storage (Permanent Pool) = 404.0 OK.
Actual Wet Storage Volume(ft')= 0 OK.
Dry Storage
Required Storage Capacity (ft') _
Min. Bev. of Principal Spillway(ft)=
Selected Bev. of Principal Spillway(ft)=
Actual Total Storage Volume (ft) _
Desired Surface Area (ft) _
Actual Surface Area at Principal Spillway (ft) _
aeanoul:
Cleanoul Requirement (%of Wet Storage)=
Geanout Requirement (%of Total Storage)=
Basin Cleanoul Volume (ft') _
Basin Geanout Elevation (ft)=
DewAtiring of Dry Storage,
Basin Shane
Option, Faircloth Skimmer
Actual Total Storage Volume to Dewater (ft') _
Required Orifice Diameter (in)_
8,460 =Required Dry Storage + Actual Wet Storage
407.8
408.0 O.K.
9,200 O.K.
523
3,773 O.K.
0 Enter "0" if Not Applicable
0 Based on %of Total Storage Volume
4040
9,200 =Volume at Principal Spillway
2.0 From www.fairclothskimmer.com Based on 2 to 5 Day Drawdown
Length of Basin (ft)= 150 Measured at Principal Spillway Elevation
Width of Basin (ft)= 50 Measured at Principal Spillway Elevation
Desired Length to Width Ratio (X1)= 2
Actual Length to Width Ratio (X1) = 3.0 O.K.
SHEET 14/16
JOB# MERRITF-21-1
DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
SMITH GARDNER
SMITH GARDNER, ING Pump Basin(reclamation) SED BASIN-CFNF Merrilts Gavel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt', travel pit SHEET 15/16
JOB# MERRITT-21-1
SUBJECT Sediment Basin Analysis DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
ROUTE DESIGN STORM: Use HydroCAD or Other Method.
Design Parameters,
Design Storm: 10-Yr, 24-Hr
Design Storm Rainfall (in)= 5.17
Rainfall Distribution: Type II
Runoff Method: SCSTR-20
Results:
Maximum Pool Elevation = 407.9
Surface Area at Maximum Pool (ft')= 3,712
Peak Discharge (cfs) = 0.0
Check Setti ing Efficiency
Particle Data:
Diam.(microns)=
40
Specific Gravity=
2.65
Settl ing Val oc.(ft/s)=
0.004140
Reynolds No. (W.5)=
0.044284 OK.
Efficiency Data,
Desired Efficiency (%) =
80
No. of Effective Cells =
1
Settling Efficiency (%) =
99.7 O.K.
DESIGN OUTLETSTRUCTURES•
Design Riser/Barrel Structures,
Riser Desicm
Type of Riser: CAMP - Circular
Top of Riser Base Elevation (ft) = 398.0
Elev. of Principal Spillway (ft)= 408.0
Riser Top Elevation (ft)= 404.0
Riser Height (ft) = 6.0
Outlets:
Outlet No. 1 (for Dewatering Dry Storage): Si— 2" Diam. For Skimmer From Above- Dewatering of Dry Storage
Invert Elevation: 398.1 May Vary For Multiple Holes
Outlet No. 2 (Principal Spillway): Si— 24' dia. CPP
Invert Elevation: 408.0
Riser Inside Diameter(ft)= 2.0
Approx. arc. Riser Interior Volume (cf)= 31
Barrel Desicm
Type of Barrel:
HOPE
Diameter (in) =
18
Inv. In Elevation (ft)=
404.0
Inv. Out Elevation (ft)=
403.0
Length (ft)=
50.0
Slope (ft/ft) =
0.020
(Top of Base to Principal Spillway)
SMITH GARDNER
SMITH GARDNER, ING Pump Basin (reclamation) SE) BASIN-(FNPRAL Merritt, Gravel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt', travel pit SHEET 16/16
JOB# MERRITT-21-1
SUBJECT Sediment Basin Analysis DATE 10/25/2021
COMPUTED BY JCL
CHECKED BY SAS
Poser Base Calculations,
Design Uplift Force
Factor of Safety=
F (unadjusted) (Ibs) _
CMP Riser Buoyant Weight (Ibs) _
Buoyant VA. of Riser Top (Ibs)=
Buoyant Wt. of Surrounding Soil Acting on Ext. Base (Ibs) _
Sliding Resistance of Surrounding Soil (Ibs) _
F (adjusted) (Ibs)=
Concrete Base:
Required Volume of Concrete (ft') _
Length (ft) _
Width (ft)=
Thickness (ft) _
Actual Volume of Concrete (ft') _
Anti -Seepage Collar Calculations: (Alternatively- Design Flltar Diaphragm)
Slope of Upstream Embankment (zHA V) =
Slope of Outlet Pipe (ft/ft) _
L. (ft) _
Number of Collars:
Length of Each Collar (ft) _
Width of Each Collar (ft) _
Collar Projection, P(ft)=
Spacing of Subsequent Anti -Seep Collars (ft) _
Emergency Spillway Calculations•
SUMMARYDI
Crest Elw. (ft)=
Required Freeboard (ft)=
Top of Bar m El ev. (ft) _
Required Capacity (cfs) _
(hiving Head (ft)=
Weir Coefficient =
Length of Crest (ft) _
Design Crest Length (ft) _
1.25
2,450
0
0
0
0
0
0
0
2,450
28.0
6.0
6.0
1.0 (Includes Concrete III Inside of Box)
36.0 OK.
3
0.020
46
2
5.5 From Design Chart Based on La and No. of Collars
5.5 From Design Chart Based on La and No. of Collars
2
28 =14P
407.0
1.0
408.0
20.0 From HydroCAD- No Outflow from 11124-Hr. Storm; Assume 20 cis Capacity
0.5 Assumed
3.0
18.9 Determine by Weir Equation"
20
Length =20 ft minimum.
Basin No.: Pump Basin (Post-Rec)
Elev. of Bottom of Basin (ft)= 404.0
Cl eanout PJ ev.(ft)= 404.0
Elev. of Wet Storage (Permanent Pool) (ft)= NA
Elev. of Principal Spillway (ft)= 408.0 See Abovefor Riser and Other Design Information.
Emergency Spillway Elev.(ft)= 407.0
Top of Bar m El ev.(ft)= 408.0
Top of Berm Wdth(ft)=_ 10
Barrel Diameter (in)= 18
Barrel Slope(%)= 2.0
SMITH GARDNER
SMITH GARDNER, ING Pump Basin (reclamation) SEED BASIN -GENERAL Merritt, Qavel Pit

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
ADDRESS TEL WEB
SMITH G A R D N E R 14 N. Boylan Avenue, Raleigh, NC 27603 919.828.0577 www.smithgardnerinc.com
PRQJECT Merritt's Gravel Pit SHEET 1 OF 2 DATE 10/25/2021
COMPUTED BY JCL
SUBJECT Outlet Protection Analysis JOB # MERRITT-21-1 CHECKED BY SAS
OBJECTIVE: To design outlet protection for culverts and/or drainage channels based on the maximum flow from the
design storm. Rip rap aprons are applicable when the Froude Number (Fr) is less than or equal to 2.5
(Debo and Reese). For higher Froude Numbers, rip rap outlet basins, baffled outlets, and/or other
methods are more appropriate.
REFERENCES: Debo, T.N., and Reese, A.J. (1995), Municipal Storm Water Management, Lewis Publishers, Boca Raton,
FL, Section 8.11 - pp. 289-290; Section 12.6 - pp. 523-526.
Federal Highway Administration (2000), Hydraulic Design of Energy Dissipators for Culverts and Channels,
Hydraulic Engineering Circular No. 14, FHWA EPD-86-110, Metric 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, INC.
ANALYSIS: For each outlet, determine the Froude Number (Fr) based on the pipe Manning's number, diameter, slope,
and design discharge. Use the methods described in Section 8.11 of Debo and Reese. Select the method
of outlet protection, as appropriate, and perform design calculations.
Rio Rap Aprons:
If Fr < 2.5, a rip rap apron may be used. The following design approach is based on Section 12.6 of Debo
and Reese and Section 8.06 of the NC Erosion & Sediment Control Planning and Design Manual:
1. Determine the tailwater condition and select the appropriate design chart.
2- Using the appropriate design chart, determine the d5o rip -rap size and minimum apron length
(La) based on the maximum design flow (Q), flow depth (d), and/or velocity (v) (depending on
whether the pipe is flowing full or partially full).
3. Using the same chart, determine apron dimensions.
4. Determine the maximum stone diameter: dmax = 1.5 x d50
5. Determine the apron thickness:
Thickness = 1.5 x dmax (No Filter Geotextile)
Thickness = 1.5 x d5o (With Filter Geotextile)
Other Methods:
If Fr > 2.5, consider the use of a rip rap basin, baffled outlet, or other device. Design method according to
FHA guidelines using HY8-Energy program (or other documented source).
SMITH GARNER, INC. OUTLET PROTECTION Merritt RTC

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
PROJECT Merritt's Gravel Pit SHEET
2/2
JOB#
MERRITT-21-1
SUBJECT Outlet Protection Analysis - Rip Rap Aprons (Circular Pipe) DATE
10/25/2021
COMPUTED BY
JCL
CHECKED BY
SAS
Rio Rap pA rom
Outlet
Sediment Basin 1
Pump Basin
Pipe Type:
CPP
CPP
Manning's Coefficient:
0.013
0.013
Diameter (Dc) (in) =
24
18
Slope (%)=
0.9
2.0
Design Discharge ids) =
1.1
7.1
Source of Discharge Data:
HydroCAD 10-Yr 24-Hr
HydroCAD 10-Yr 24-Hr
K =
0.016
0.149
0(degrees)=
265
265
Flow Depth (d) (in) =
20.1
15.1
Flow Area (ft2) =
2.8
1.6
Flow Velocity (v) (ft/sec) =
0.4
4.5
Froude Number =
0.05
0.71
RipRap Aprons Applicable?
Yes
Yes
Tailwater Condition (Low or High)*:
Low
Low
d5o (ft)** =
0.50
0.50
dmex(ft)=
0.75
0.75
Apron Thickness (Q (ft):
-----
-----
No Geotextile:
1.13
1.13
With Geotexti I e:
0.75
0.75
Apron Dimensions (ft):
-----
-----
Length (La)** =
10
10
Width (W)=
12.0
11.5
*Tail water Conditions: Low: Tw<0.5Dc; High: Tw>0.5Dc
** Value from Chart.
SMITH GARDNER
SMITH GARGNER, INC. Rip Rap Aprons (Circular Pipe) CUTLET PROTECTION Merritt RTC

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
Appendices
3 D. ----7
10 20 50 100 200 500 1000
Discharge (ft3/sec)
Curves may not be extrapolated.
Figure 8.06a Design of outlet protection protection from a round pipe flowing full, minimum tailwater condition (TW < 0.5 diameter).
Rev. 12/93 8.06.3

DocuSign Envelope ID: DAC5B422-15D5-47D1-9869-38C679B551BD
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