Revised_Allen CBE - Appendix C _20200129

APPENDIX Cl
STORMWATER

AECOM
Job Duke Energy —Allen Closure by Project No. 60603204 Sheet 1 of 6
Excavation
Description Stormwater Calculations
Computed by NSF Date 1/15/20
Checked by DMB Date 1/15/20
The purpose of this analysis is to provide preliminary conveyance designs for managing surface
water runoff from the 25-year, 24-hour and the 100-year, 24-hour storm event over the proposed
final grades of the Allen Steam Station Active Ash Basin (AAB) and Retired Ash Basin (RAB) under
post -closure conditions. The location of conveyance channels, culverts, detention ponds, and
existing and proposed spillways are shown in Attachment Cl-A.
SITE AND PROJECT DESCRIPTION
The AAB and RAB are located south of the Allen Steam Station and adjacent to Lake Wylie/the
Catawba River. They are situated between topographic divides located along South Point Road to
the west, along Plant Allen Road and the RAB north dike to the north, and the Duke Energy property
boundary to the south. The natural topography at the site generally slopes downward from these
divides to the Ash Basin and subsequently toward Lake Wylie/the Catawba River. The total drainage
area contributing to the existing AAB outlet is approximately 293 acres, and the total drainage
contributing to the existing RAB outlet is approximately 233 acres (URS, 2014). The land area outside
of the existing AAB and RAB water level boundaries consists primarily of suburban homes,
vegetation consisting of grasses and wooded areas, coal ash management facilities, and closed
landfills and structural fills with vegetative covers.
Storm and process water from the AAB previously discharged through a weir box outlet structure
located in the southeast corner of the basin. The weir box and spillway system was constructed in
2016 as a replacement to the prior reinforced concrete riser structure and associated RCP piping.
The discharge flow was conveyed through a 48-inch HDPE pipe system which ties into the pre-
existing 42-inch diameter RCP near the downstream toe -of -slope via a reinforced concrete manhole
structure (AECOM, 2018). As of February 9, 2019, process flows no longer enter the AAB. Decanting
of the AAB began on June 3, 2019.
Storm water from the RAB discharges through its primary spillway via a headwall structure (Outfall
SW015) located in the ditch in the southeast corner of the basin (AECOM, 2018). The primary
spillway was constructed in 2016 as a replacement to the prior reinforced concrete riser structure
and associated RCP piping. The discharge flow is currently conveyed through a 54-inch and 42-inch
diameter HDPE pipe system (AECOM, 2018). The primary spillway ties into the existing 36-inch
diameter RCP near the downstream toe -of -slope via a reinforced concrete manhole structure. In
addition to the primary spillway, an emergency spillway was installed for the RAB in 2015 (AECOM,
2018).
The Allen Closure Project (closure project) will consist of removing the free water from the AAB,
excavating the existing CCR materials (in the AAB and in the existing RAB landfill) to support the

AECOM
Job Duke Energy —Allen Closure by Project No. 60603204 Sheet 2 of 6
Excavation
Description Stormwater Calculations
Computed by NSF Date 1/15/20
Checked by DMB Date 1/15/20
construction of a two new landfills (one in the AAB and one in the northwest corner of the RAB),
and constructing several channels and detention basins to convey drainage of stormwater from the
final closure grades to one of two outfall locations along Lake Wylie. The AAB dam will be breached
at the location of the existing spillway and a detention basin will be constructed upstream of the
breach. The southern portion of the AAB landfill will be graded to drain to this new detention basin
which will then discharge directly to Lake Wiley/the Catawba River.
Within the RAB, the existing RAB landfill will be removed and a new detention basin will be
constructed in the northeast corner of the RAB. The northern portion of the AAB landfill and then
entire RAB area will be graded to drain to this new detention basin which will then discharge directly
to Lake Wiley/the Catawba River. The RAB dam will be breached in this location prior to the
installation of this new detention basin. No flows are proposed to drain towards or discharge
through the existing primary and emergency spillways in the RAB.
The final designs will include stormwater conveyance channels that collect runoff from the drainage
basin and safely convey stormwater flows to the two detention basins. The existing AAB and RAB
spillways will be abandoned. For the proposed channels, detailed design of the geometry and the
armoring has not yet been conducted and is not included in this analysis. Conceptual results are
shown in Attachment CI-B.
The following sections summarize the design criteria, procedures, assumptions, and results of the
channel and culvert design activities.
DESIGN CRITERIA
The design criteria for the project are applicable to the stormwater conveyance channels,
detentions basins, and spillways on and adjacent to the closure area. These criteria include
requirements established for ash basin closure, and requirements from the North Carolina
Department of Environmental Quality (NCDEQ) Erosion and Sediment Control Planning and
Design Manual (NCDEQ, 2013).
Channel Design Criteria
The design requirements include conveyance of runoff from the 25-year, 24-hour storm event
with a minimum of 6 inches of freeboard from the water surface elevation (WSE) within the
proposed channels to the cover system lateral drainage layer outlet (as applicable) in the side of
the channel, while also conveying the 100-year, 24-hour storm event without overtopping the
channel bank. The channels are proposed to be constructed in a manner to convey stormwater
runoff throughout the AAB and RAB and to direct this runoff to one of the three detention basins
and their respective outfalls.

AECOM
Job Duke Energy — Allen Closure by Project No. 60603204 Sheet 3 of 6
Excavation
Description Stormwater Calculations
IV.
Computed by NSF Date 1/15/20
Checked by DMB Date 1/15/20
The NCDEQ Erosion and Sediment Control Planning and Design Manual (NCDEQ, 2013) requires
channels to convey runoff for the design storm (25-year, 24-hour storm event) while providing
protection from erosion for the design velocities within the channel. Detailed design of the
stormwater channels will be completed in a future submittal.
Detention Basin Design Criteria
The detention basins will be sized to attenuate the peak stormwater flows from the 100-year, 24-
hour storm event with a minimum of 1 foot of freeboard in the proposed conditions. The detention
basins will also be sized to convey stormwater through the outlet culverts without activating the
emergency spillway during the 100-year, 24-hour storm event.
Spillway Design Criteria
The existing AAB and RAB spillways will be abandoned and both dams will be breached, so neither
will be required to pass the Probable Maximum Precipitation (PMP) storm event in the proposed
conditions.
PpnrF:ni iRF
Channel and Detention Basin Desi
The proposed topography of the site was used to estimate slopes for the conveyance channels
and culverts. The minimum channel slopes will be 0.5%. A conceptual proposed stormwater
management plan used for the channel and detention basin calculations in this report is included
in Attachment Cl-A.
HydroCAD (Version 10.00) modeling software was used to conduct the hydrologic and hydraulic
calculations for this analysis. To start the analysis, conceptual drainage areas were established at
various locations within the AAB and RAB from the two outfalls upstream through the proposed
drainage channels and culverts. Design inputs to the model were based on the drainage areas,
runoff curve numbers, length of reaches between sub -drainage areas, channel and culvert
geometry, rainfall data, and Manning's coefficients. Generation of hydrographs within the model
was based on methodology and criteria provided in the Natural Resources Conservation Service's
(NRCS) Technical Release 55 (NRCS, 1986). The model was used to generate peak flow rates,
velocities, and depth of flow within the proposed channels and detention basins during the
design storms. The HydroCAD model output can be found in Attachment C1-13.
NOTES/ASSUMPTIONS
The following is a list of key notes and assumptions made in completing this analysis.

AECOM
Job Duke Energy — Allen Closure by Project No. 60603204 Sheet 4 of 6
Excavation
Description Stormwater Calculations
V.
Computed by NSF Date 1/15/20
Checked by DMB Date 1/15/20
• The 25-year and 100-year storm rainfall amounts were obtained from the NOAA Atlas 14
Point Precipitation Frequency Data Server. The rainfall amounts were applied within the
model according to the 24-hour NRCS Type II distribution.
• Within the HydroCAD program, runoff was calculated using the Soil Conservation Service
(SCS) TR-20 method.
• Runoff curve numbers (CNs) used in the analysis were 80 for cover system areas. A CN of
between 60 and 75 was used for areas outside of the cover system as appropriate based
on their land use and hydrologic soil group per tables provided in NRCS Technical Release
55 (NRCS, 1986). In general, most areas outside of the basin can be characterized as
residential or wooded areas in good condition with hydrologic soil group B.
• The time of concentration was calculated using HydroCAD, which includes inputs for each
drainage area for the longest hydraulic flow path and average land slope.
• Manning's "n" factors used were 0.045 for grass lined channels, 0.025 for Fabriform or
equivalent structural lined channels, 0.012 for concrete box culverts, and 0.013 for
smooth interior corrugated PE culverts.
• The values provided in this submittal may change as the design is refined and updated in
future submittals.
SUMMARY OF RESULTS
Channels
All channels in the proposed conditions have been preliminarily sized based on the conceptual
stormwater management plan in Attachment Cl-A; however, they have not been analyzed in
detail. Detailed design of the stormwater channels will be completed in a future submittal.
Detention Basin
The detention basins have been sized to attenuate the peak stormwater flows from the 100-year,
24-hour storm event in the proposed conditions. Each detention basin is also below the minimum
height and storage volume (25 feet and 50 acre-feet, respectively) for a structure to be classified as
a dam as outlined in the North Carolina Dam Safety Law of 1967 (NC General Statutes, 1967). See
Table 1 below for a summary of the detention basins and their peak discharges during the 100-year,
24-hour storm event. The values shown below may change as the design is refined and updated in
future submittals.

AECOM
Job Duke Energy — Allen Closure by
Excavation
Description Stormwater Calculations
Project No. 60603204
Computed by NSF
Checked by DMB
Table 1— Detention Basin Summary
Sheet 5 of 6
Date 1/15/20
Date 1/15/20
Detention
Height (ft)
Storage
Outlet
Discharge
Peak 100-
Basin
Volume (ac-
Structure
Location
year
ft)
Discharge
(cfs)
Upstream of
16
48
Two 20-inch
Lake Wiley
73
AAB dam
Culverts
breach
Upstream of
16
48
Two 36-inch
Lake Wiley
247
RAB dam
Culverts
breach
Additional detailed results can be found in the HydroCAD model output report in Attachment Cl-
B.
VI. CONCLUSIONS
The proposed grading of the closed AAB and RAB, in combination with the design of the proposed
channels and detention basins is sufficient to safely control and convey their respective design
storms as presented above. The detentions ponds have a minimum of 1 foot of freeboard and
convey stormwater through the outlet culverts without activating the emergency spillway during
the 100-year, 24-hour storm event. Wave action has not be analyzed at this time; however, 1 foot
of freeboard is anticipated to be adequate based on the size of the detention basins.
VII. ATTACHMENTS
Attachment Cl-A: Figures
Attachment Cl-B: HydroCAD Report

AECOM
Job Duke Energy —Allen Closure by Project No. 60603204 Sheet 6 of 6
Excavation
Description Stormwater Calculations Computed by NSF Date 1/15/20
Checked by DMB Date 1/15/20
VIII. REFERENCES
AECOM, 2018. Phase 2 Reconstitution of Ash Pond Designs Report (Rev. 4), Allen Steam Station.
April 26, 2018.
Applied Weather Associates. (2019). Site -Specific Probable Maximum Precipitation Study, Allen
Basin, North Carolina, 2019.
Natural Resources Conservation Service (NRCS). (1986). "Urban hydrology for small watersheds."
Technical release No. 55, U.S. Dept. of Agriculture, Washington, D.C.
North Carolina Department of Environmental Quality (NCDEQ). (2013). Erosion and Sediment
Control Planning and Design Manual, May 2013.
North Carolina General Statutes, Chapter 143. (1967). North Carolina Dam Safety Law of 1967.
NOAA, National Weather Service (2018) Precipitation -Frequency Atlas of the United Stated Point
Precipitation Frequency Estimates by NOAA Atlas 14, Volume 2, Version 3; (NOAA website:
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html
Probable Maximum Precipitation Estimates, United States East of the 105th Meridian.
Hydrometeorological Report No. 51. NOAA. June 1978.
http://www.nws.noaa.gov/oh/hdsc/studies/pmp.html#PMP documents
URS Corporation (URS). (2014). Hydrologic and Hydraulic Analysis, Allen Steam Station Ash Ponds.
December 2014.

ATTACHMENT Cl-A
FIGURES

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(GASTO-016)
CONCEPTUAL DAM BREACH GRADING
(SEE NOTE 1.3 IN GENERAL NOTES,
DRAWING NO. ALN_C999.001.012)
PROPOSED DETENTION BASIN
2-36" CULVERT OUTLETS. INLET ELEVATION 566.0 FT.
EMERGENCY SPILLWAY ELEVATION 581 FT.
LAKE WYLIE/
CATAWBA RIVER
NORMAL W.S.E. 565.7 FT.
100-YEAR
FLOOD
ELEVATION:
571.3 FT.
EMERGENCY SPILLWAY
(TO BE ABANDONED)
625
--62!
ALN C999.001.027 wv. A
LEGEND
PROPOSED MAJOR CONTOUR (25 FOOT)
PROPOSED MINOR CONTOUR (5 FOOT)
EXISTING MAJOR CONTOUR (25 FOOT)
EXISTING MINOR CONTOUR (5 FOOT)
DUKE ENERGY PROPERTY BOUNDARY
APPROXIMATE LIMITS OF IMPOUNDED ASH
APPROXIMATE ASH BASIN WASTE BOUNDARY
�•�••� LIMITS OF WATER
100—YR 100 YR FLOOD LINE
STORMWATER FLOW DIRECTION
0
PERMITTED SPILLWAY
(TO BE ABANDONED) NOTES
NPDES
OUTFALL
SWO15
;il COAL YARD SUMP
DISCHARGE
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PROPOSED DETENTION BASIN
2-20" CULVERT OUTLETS. INLET ELEVATION 566.0 FT. 1�T
EMERGENCY SPILLWAY ELEVATION 581 FT. 1�
CONCEPTUAL DAM BREACH GRADING
(SEE NOTE 1.3 IN GENERAL NOTES,
DRAWING NO. ALN_C999.001.012)
ft
JURISDICTIONAL STREAM
HATCH LEGEND
WETLAND (SEE NOTE 4)
POTENTIAL HABITAT - SCHWEINITZ'S
SUNFLOWER (SEE NOTE 3)
PROPOSED DETENTION BASIN
1. LIMITS OF IMPOUNDED ASH ARE APPROXIMATE.
2. REFER TO SHEET ALN_C999.001.012 FOR REFERENCES.
3. POTENTIAL HABITAT FOR SCHWEINITZ'S SUNFLOWER WAS IDENTIFIED BY AMEC'S JUNE
24, 2015 NATURAL RESOURCES TECHNICAL REPORT. PRIOR TO LAND DISTURBANCE,
THE U.S. FISH AND WILDLIFE SERVICE MAY REQUIRE A BIOLOGICAL SURVEY OF THESE
D
AREAS.
r
z
4. POTENTIAL JURISDICTIONAL WATERS (STREAMS/WETLANDS) WERE IDENTIFIED BY
I
AMEC'S JUNE 24, 2015 NATURAL RESOURCES TECHNICAL REPORT AND SURVEYED BY
MCKIM & CREED IN FEBRUARY 2016. CONFIRMATION IS PENDING U.S. ARMY CORPS OF
ENGINEERS REVIEW.
C4
5. WORK WITHIN THE 100-YEAR FLOODPLAIN ALONG THE SHORELINE OF THE CATAWBA
RIVER MAY REQUIRE PERMITTING.
Q
6. EXISTING TRUCK WASH AND SCALES TO THE NORTH OF ASH FILL 1 MAY NOT BE
LOCATED WITHIN THE ASH BASIN LIMITS SHOWN ON THE DRAWINGS. THIS WILL NEED
•
TO BE VERIFIED PRIOR TO CONSTRUCTION.
O
N
7. THE INTENT IN BREACHING THE RAB AND AAB DIKES IS TO REMOVE THE DIKES FROM
REGULATION AS DAMS. THIS WILL BE ACCOMPLISHED BY PERFORMING A FULL LOCAL
BREACH, I.E. TO REMOVE A PORTION OF THE DIKE COMPLETELY DOWN TO NATIVE
GROUND AT ITS LOWEST POINT SUCH THAT THE DIKE WILL NOT IMPOUND WATER OR
CCR MATERIAL. A SEPARATE NEW BERM WILL BE BUILT AROUND THE FUTURE
STORMWATER MANAGEMENT AREA FOR LONG-TERM STORMWATER TREATMENT.
8. STORMWATER CHANNEL GRADING IN THE RAB AND NORTH/NORTHWEST PART OF THE
AAB IS NOT SHOWN ON THIS PLAN. THIS GRADING HAS BEEN CONSIDERED AT A
CONCEPT LEVEL TO VERIFY ITS FEASIBILITY AND WILL BE SHOWN AS PART OF FUTURE
•
DETAILED DESIGN.
0 300 600
900
— LAKE WYLIE
LAKE WYLIE/
NOT FOR CONSTRUCTION
100-YEAR
CATAWBA RIVER
FLOOD
NORMAL W.S.E.
GRAPHIC SCALE
(IN FEET)
ELEVATION:
565.7 FT.
571.3 FT.
TITLE
FINAL SURFACE WATER MANAGEMENT
PLAN
- NPDES
OUTFALL
002
ALLEN STEAM STATION
PERMITTED SPILLWAY
CCR SURFACE IMPOUNDMENT CLOSURE PLAN DRAWINGS -
CBE
(TO BE ABANDONED)
GASTON COUNTY, NORTH CAROLINA
N.C. ENGINEERING LICENSE NO.
FOR ISSUED FOR APPROVAL
F-0342
— JURISDICTIONAL STREAM
SEAL
SCALE: AS SHOWN
DES:
ANR
DUKE DWG TYPE:. DWG
DFTR:
AMC
ENFlkGY®
DATE: 01 - 1 - 0
ENGR:
JDM
FILENAME: ALN-C999.001.027 FINAL SURFACE WATER MANAGEMENT PLAN.DWG APPD: JDM
DWG SIZE DRAWING NO. REVISION
ANSI 22.0"x34.0" ALN C999.001.027 A
—
INCHES
TENTHS i0
1

ATTACHMENT C1-6
HydroCAD Modeling Output

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Subcat Reach on Link
a
Routing Diagram for Closure Plan HydroCAD model 1.13.20
Prepared by AECOM, Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Page 2
Area Listing (all nodes)
Area
CN
Description
(acres)
(subcatchment-numbers)
18.541
60
(102S)
31.826
80
(102S)
18.639
61
>75% Grass cover, Good, HSG B (102S, 107Sa)
85.277
74
>75% Grass cover, Good, HSG C (106S, 201 S, 202S, 203S)
177.910
80
Final Cover (103S, 104S, 105Sa, 106S, 107Sa, 107Sb, 108S, 201 S, 202S)
50.505
74
Pasture/grassland/range, Good, HSG C (204S)
68.566
75
Residential (106S, 107Sa, 201 S)
48.379
60
Woods (106S, 201 S)
14.233
60
Woods, Fair, HSG B (202S)
513.877
74
TOTAL AREA

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Page 3
Soil Listing (all nodes)
Area Soil
Subcatchment
(acres) Group
Numbers
0.000 HSG A
32.872 HSG B
102S, 107Sa, 202S
135.783 HSG C
106S, 201 S, 202S, 203S, 204S
0.000 HSG D
345.222 Other
102S, 103S, 104S, 105Sa, 106S, 107Sa, 107Sb, 108S, 201 S, 202S
513.877
TOTAL AREA

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
HvdroCAD® 10.00-25 s/n 09114 © 2019 HvdroCAD Software Solutions LLC
Ground Covers (all nodes)
HSG-A HSG-B HSG-C HSG-D Other Total Ground
(acres) (acres) (acres) (acres) (acres) (acres) Cover
Allen CbE Jan. 2020
Printed 1/15/2020
Paae 4
Subcatchment
Numbers
0.000 0.000 0.000 0.000 50.367 50.367 102
S
0.000 18.639 85.277 0.000 0.000 103.916 >75% Grass cover, Good 102
S,
106
S,
107
Sa,
201
S,
202
S,
203
S
0.000 0.000 0.000 0.000 177.910 177.910 Final Cover 103
S,
0.000
0.000
50.505
0.000
0.000
0.000
0.000
0.000
0.000
68.566
0.000
0.000
0.000
0.000
48.379
104
S,
105
Sa,
106
S,
107
Sa,
107
Sb,
108
S,
201
S,
202
S
50.505 Pasture/grassland/range, Good 204
S
68.566 Residential 106
S,
107
Sa,
201
S
48.379 Woods 106
S,
201
S

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
HvdroCAD® 10.00-25 s/n 09114 © 2019 HvdroCAD Software Solutions LLC
Ground Covers (all nodes) (continued)
HSG-A HSG-B HSG-C HSG-D Other Total Ground
(acres) (acres) (acres) (acres) (acres) (acres) Cover
Allen CbE Jan. 2020
Printed 1/15/2020
Paae 5
Subcatchment
Numbers
0.000 14.233 0.000 0.000 0.000 14.233 Woods, Fair 202
S
0.000 32.872 135.783 0.000 345.222 513.877 TOTAL AREA

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC
Allen CbE Jan. 2020
Printed 1/15/2020
Page 6
Pipe Listing
(all nodes)
Line#
Node
In -Invert
Out -Invert
Length
Slope
n
Diam/Width
Height
Inside -Fill
Number
(feet)
(feet)
(feet)
(ft/ft)
(inches)
(inches)
(inches)
1
100P
566.00
565.00
100.0
0.0100
0.013
20.0
0.0
0.0
2
103P
565.00
564.00
100.0
0.0100
0.013
20.0
0.0
0.0
3
104P
566.00
565.00
100.0
0.0100
0.013
36.0
0.0
0.0
4
107P
565.00
564.00
100.0
0.0100
0.013
30.0
0.0
0.0
5
108P
611.00
606.00
50.0
0.1000
0.012
42.0
0.0
0.0
6
200
570.20
566.40
114.3
0.0332
0.012
36.0
0.0
0.0
7
200
606.12
570.20
56.3
0.6380
0.013
42.0
0.0
0.0
8
200
609.10
606.12
27.3
0.1092
0.013
42.0
0.0
0.0
9
200
611.09
609.10
20.5
0.0971
0.013
54.0
0.0
0.0

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type // 24-hr 25-year Rainfall=5.87"
Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 7
Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points x 3
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method
Subcatchment 102S: DA 102 Runoff Area=2,301,379 sf 0.00% Impervious Runoff Depth=2.89"
Flow Length=850' Tc=10.2 min CN=72 Runoff=233.68 cfs 12.712 of
Subcatchment 103S: DA 103 Runoff Area=1,375,819 sf 0.00% Impervious Runoff Depth=3.66"
Flow Length=1,200' Tc=11.8 min CN=80 Runoff=165.48 cfs 9.644 of
Subcatchment104S: Area Draining to 104 Runoff Area=1,224,363 sf
0.00% Impervious Runoff Depth=3.66"
Flow Length=1,000' Tc=13.9 min
CN=80 Runoff=137.58 cfs 8.583 of
Subcatchment 105Sa: Area draining to 105 Runoff Area=914,000 sf
0.00% Impervious Runoff Depth=3.66"
Flow Length=2,150' Tc=32.6 min CN=80 Runoff=63.27 cfs 6.407 of
Subcatchment 106S: DA 106 Runoff Area=3,568,027 sf
0.00% Impervious Runoff Depth=2.79"
Flow Length=1,935' Tc=24.2 min
CN=71 Runoff=226.60 cfs 19.074 of
Subcatchment107Sa: Northwest AAB Runoff Area=1,934,630 sf
0.00% Impervious Runoff Depth=2.79"
Flow Length=1,050' Tc=14.1 min
CN=71 Runoff=165.45 cfs 10.342 of
Subcatchment 107Sb: NW of North face of Runoff Area=513,700 sf
0.00% Impervious Runoff Depth=3.66"
Flow Length=1,050' Tc=14.1 min CN=80 Runoff=57.27 cfs 3.601 of
Subcatchment 108S: Area draining to 102 Runoff Area=924,571 sf
0.00% Impervious Runoff Depth=3.66"
Flow Length=750' Tc=10.0 min
CN=80 Runoff=118.38 cfs 6.481 of
Subcatchment201 S: DA 201 Runoff Area=4,998,000 sf 0.00% Impervious Runoff Depth=2.89"
Flow Length=750' Tc=28.7 min CN=72 Runoff=293.94 cfs 27.607 of
Subcatchment202S: DA 202 Runoff Area=1,830,000 sf 0.00% Impervious Runoff Depth=2.79"
Flow Length=400' Tc=22.8 min CN=71 Runoff=120.15 cfs 9.783 of
Subcatchment203S: DA 203 Runoff Area=600,000 sf 0.00% Impervious Runoff Depth=3.08"
Flow Length=700' Tc=14.2 min CN=74 Runoff=56.45 cfs 3.531 of
Subcatchment204S: RAB Landfill Area Runoff Area=2,200,000 sf 0.00% Impervious Runoff Depth=3.08"
Flow Length=100' Slope=0.0200 '/' Tc=10.0 min CN=74 Runoff=239.25 cfs 12.946 of
Reach 102R: Ditch 102 Avg. Flow Depth=1.86' Max Vet=5.94 fps Inflow=454.15 cfs 38.267 of
n=0.025 L=2,400.0' S=0.0054 '/' Capacity=1,916.64 cfs Outflow=392.71 cfs 38.267 of
Reach 104: Ditch 104 Avg. Flow Depth=0.77' Max Vet=3.65 fps Inflow=137.58 cfs 8.583 of
n=0.025 L=1,550.0' S=0.0058'/' Capacity=2,039.57 cfs Outflow=118.45 cfs 8.583 of
Reach 106R: Ditch 106 Avg. Flow Depth=1.35' Max Vet=4.71 fps Inflow=226.60 cfs 19.074 of
n=0.025 L=1,210.0' S=0.0050'/' Capacity=1,833.82 cfs Outflow=217.35 cfs 19.074 of
Reach 107Ra: Ditch 107_Shallow Avg. Flow Depth=1.35' Max Vet=5.55 fps Inflow=261.46 cfs 20.350 of
n=0.025 L=870.0' S=0.0069 '/' Capacity=1,739.55 cfs Outflow=254.49 cfs 20.350 of

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type // 24-hr 25-year Rainfall=5.87"
Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 8
Reach 107Rb: Ditch 107_Steep Avg. Flow Depth=0.73' Max Vet=10.85 fps Inflow=254.49 cfs
20.350 of
n=0.025 L=570.0' S=0.0561 T Capacity=4,963.15 cfs Outflow=253.84 cfs
20.350 of
Reach 109R: Ditch 105 Avg. Flow Depth=0.66' Max Vet=8.82 fps Inflow=118.38 cfs
6.481 of
n=0.025 L=950.0' S=0.0442 '/' Capacity=2,959.13 cfs 0utflow=116.03 cfs
6.481 of
Reach 206Ra: Channel 201 Avg. Flow Depth=1.56' Max Vet=5.15 fps Inflow=293.94 cfs
27.607 of
n=0.025 L=1,800.0' S=0.0050'/' Capacity=8,724.30 cfs Outflow=278.61 cfs
27.607 of
Reach 206Rb: Channel 201 Avg. Flow Depth=2.26' Max Vet=6.36 fps Inflow=571.87 cfs
60.902 of
n=0.025 L=2,430.0' S=0.0049 '/' Capacity=8,670.28 cfs Outflow=528.74 cfs
60.902 of
Reach 207R: Channel 202 Avg. Flow Depth=0.91' Max Vet=3.73 fps Inflow=120.15 cfs
9.783 of
n=0.025 L=1,300.0' S=0.0050'/' Capacity=8,724.30 cfs 0utflow=111.86 cfs
9.783 of
Reach 208R: Channel 202 Avg. Flow Depth=1.04' Max Vet=4.04 fps Inflow=143.68 cfs
13.313 of
n=0.025 L=1,100.0' S=0.0050'/' Capacity=8,724.30 cfs Outflow=138.94 cfs
13.313 of
Pond 10OP: SE Detention Option 1 Peak Elev=576.13' Storage=1,214,565 cf Inflow=643.02 cfs
56.493 of
Primary=61.30 cfs 57.339 of Secondary=0.00 cfs 0.000 of Outflow=61.30 cfs
57.339 of
Pond 103P: SW Detention Option 2 Peak EIev=566.00' Storage=35,000 cf Inflow=0.00 cfs
0.000 of
Primary=4.65 cfs 0.530 of Secondary=0.00 cfs 0.000 of Outflow=4.65 cfs
0.530 of
Pond 104P: NE Detention Option 1 - Peak EIev=576.24' Storage=1,108,735 cf Inflow=666.63 cfs
74.216 of
Primary=201.18 cfs 74.973 of Secondary=0.00 cfs 0.000 of Outflow=201.18 cfs
74.973 of
Pond 107P: East SW Detention Option 3 Peak EIev=566.00' Storage=35,000 cf Inflow=0.00 cfs
0.000 of
Primary=3.12 cfs 0.529 of Secondary=0.00 cfs 0.000 of Outflow=3.12 cfs
0.529 of
Pond 108P: RAB Ex. Spillway (no storage) Peak EIev=0.00'
Primary=0.00 cfs 0.000 of Secondary=0.00 cfs 0.000 of Tertiary=0.00 cfs
0.000 of
Pond 200: RAB Outlet Pond (no storage) Peak EIev=0.00'
Primary=0.00 cfs 0.000 of Secondary=0.00 cfs 0.000 of Tertiary=0.00 cfs
0.000 of
Link 102L: Lake Wylie/Catawba River
Link 104L: Lake Wylie/Catawba River
Inflow=61.30 cfs 58.398 of
Primary=61.30 cfs 58.398 of
Inflow=201.18 cfs 74.973 of
Primary=201.18 cfs 74.973 of
Total Runoff Area = 513.877 ac Runoff Volume = 130.709 of Average Runoff Depth = 3.05"
100.00% Pervious = 513.877 ac 0.00% Impervious = 0.000 ac

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type // 24-hr 25-year Rainfall=5.87"
Printed 1/15/2020
HvdroCAD®10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Paae 9
Summary for Subcatchment 102S: DA 102
Runoff = 233.68 cfs @ 12.02 hrs, Volume= 12.712 af, Depth= 2.89"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf) CN DescriDtion
807,646 60
107,375 61 >75% Grass cover, Good, HSG B
1,386,358 80
2,301,379 72 Weighted Average
2,301,379 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
6.6 100
0.0500
0.25
Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
3.6 750
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fDs
10.2 850 Total
Subcatchment 102S: DA 102
Hydrograph
❑ Runoff
0
240
24
233.68 cfs
t I
t I
t
230
220
210
t
200
190
180
It
�ItIt1
t
170
160
It
tltItI
t
150
v10
3 130
t
O
t
t
0 120
1110
100
t
�t1tI
t
90
80
t
tI
t1
t
70
60
50
_
1t
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t
40
20
t
10
t-I �-� I-t I -t � -t I J�Y�� j I 7j�-r�
t t It
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ip�
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t t H
t 1-1 1 t 1 t1 t t
IF71 I t
I-q t 7 1 t t F-I
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 10
Summary for Subcatchment 103S: DA 103
Eastern Face of Mound
Runoff = 165.48 cfs @ 12.03 hrs, Volume= 9.644 af, Depth= 3.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf) CN Description
1,375,819 80 Final Cover
1,375,819 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
6.6 100
0.0500
0.25
Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
5.2 1,100
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
11.8 1,200 Total
Subcatchment 103S: DA 103
Hydrograph
165.48 cfs — I ❑Runoff
4 1 1 4I �-I �-I 145ly6""fi-1W5JOL't
l3u
120
110Lt
L
LI
El
LIR"'7`
T�fyZill
190
c
=
T
T
T
Ft
L1
LL 80
70
1-7 -
-
T I
T I
T
F1
F-I
I7
1-�
I - 7 1 41.&:inf
6050
40
1�
t I
t I
t
t-I
�-I
I�
I
1-� I t I t I t I �I
30
I�
+ 1
+1
H
H
H
1-t
1 + I i-I
120
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 11
Summary for Subcatchment 104S: Area Draining to 104
Runoff = 137.58 cfs @ 12.06 hrs, Volume= 8.583 af, Depth= 3.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf) CN Description
1,224,363 80 Final Cover
1,224,363 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
9.6 100
0.0500
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.41"
4.3 900
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
13.9 1,000 Total
Subcatchment 104S: Area Draining to 104
Hydrograph
I� �I�IL
LI
i� I-4 -1LI L -I
150
140
137.58 cfs
L 1
L 1
L
LI
LI
IL IL I L L I +� J�.jj ,
120
rt
t I
t I
tl
t-I
�I
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_
110
I
�- I
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�-1
I-Rulnpff $klrpa��t?? 41,:�6� 0
190
L
�R
w
v
Runoff Depth= 66"
LL 80
1� 4
1
1
LI
H
H
I� 1� F�o�v� le ith=4J,66�
60
Ill.
50
j
t I
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t-
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H
H 1-tI J I I t I t� I
40
30
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L I LL
20
rtl�lfil
_
I I
�I
I� ICI I I I'�I I ILI1 1
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 12
Summary for Subcatchment 105Sa: Area draining to 105
Runoff = 63.27 cfs @ 12.28 hrs, Volume= 6.407 af, Depth= 3.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf) CN Description
914,000 80 Final Cover
914,000 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
9.6
100
0.0500
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.41"
4.5
950
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
18.5
1,100
0.0200
0.99
Shallow Concentrated Flow, shallow 2
Short Grass Pasture Kv= 7.0 fps
32.6 2,150 Total
Subcatchment 105Sa: Area draining to 105
Hydrograph
+
+
6511
1 63.27 cfs I L
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LI LI L 11
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50
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40
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1
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LL 30
14
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`en
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25
20
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TI
TI
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T I T 171
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F-I FI n I-t IT IT IT IT
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
■ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 13
Summary for Subcatchment 106S: DA 106
Area that drains using HydroCAD catchmentarea +38.75 acres to the southwest of the basin by the pond
Runoff = 226.60 cfs @ 12.18 hrs, Volume= 19.074 af, Depth= 2.79"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf) CN Description
1,208,372 60 Woods
962,761 75 Residential
305,686 74 >75% Grass cover, Good, HSG C
1,091,208 80 Final Cover
3,568,027 71 Weighted Average
3,568,027 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
9.5
100
0.0200
0.18
Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
14.1
1,235
0.0436
1.46
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.6
600
0.0100
17.56
1,264.11 Trap/Vee/Rect Channel Flow,
Bot.W=30.00' D=2.00' Z= 3.0 '/' Top.W=42.00'
n= 0.012
24.2 1,935 Total

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 14
Subcatchment 106S: DA 106
Hydrograph
r
itltIti
I I
tl
tl
It i I I t I t I t I tl t
250
240
230
220
226.60
cfs--F
+ I
t I
t I
t
t
t t 1 t I t 1
200
t 1
t 1
t l
D
CI
It 45Lie"" fid- kiF5JO t
1
180
t
t
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t
t
IR4np# lrfl ate,§Q1,97 0
150
It
1-
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t I
t l
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Iut160
140
RunoffVC 7��
0 120
It
i-
t I
t I
t l
tl
tl
It It 14D 1 1
110
100
1t -
-
1
t I
t
t
t
t t 1 t t Ali
90
80
70
60
50
1t
t I
tI
tl
-1
H
It 1--tI- t I t I tl tl t
40
20
It
t I
t
�-I
�-I
It 1-4 14 t 1 t 14-1 4-1 �I
10
0
0 2 4 6 8 10 12 14 16
1820 22 24 26 28 30
32 34
Time
36 38 40 42 44 46 48 50 52 54 56 58 60 62 6466 6870 72
(hours)
❑ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 15
Summary for Subcatchment 107Sa: Northwest AAB
Runoff = 165.45 cfs @ 12.06 hrs, Volume= 10.342 af, Depth= 2.79"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf) CN Description
456,118 80 Final Cover
704,538 61 >75% Grass cover, Good, HSG B
773,974 75 Residential
1,934,630 71 Weighted Average
1,934,630 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
9.6 100
0.0500
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.41"
4.5 950
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fDs
14.1 1,050 Total
Subcatchment 107Sa: Northwest AAB
Hydrograph
180
170
165.45
cfs
1
� I
�I
�I
I� I-4 14 4 17 + L� �.
160
150
I�
4
1
4-1
4-
�1
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140
130
z
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110
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-
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100
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-
-Io
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IRIn ff Dh=2.7 "
— —�eL j
LL 80
70
_
I-
I
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T
E1
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I7 17 17 7 1 U 4.-inf
6050
IG"71
4030
t I
t I
t I
t-I
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II I t l fi l fit �I
120
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 16
Summary for Subcatchment 107Sb: NW of North face of AAB
Runoff = 57.27 cfs @ 12.06 hrs, Volume= 3.601 af, Depth= 3.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf) CN Description
513,700 80 Final Cover
513,700 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
9.6 100
0.0500
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.41"
4.5 950
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
14.1 1,050 Total
Subcatchment 107Sb: NW of North face of AAB
Hydrograph
60 57.27
55�
50 IH I -t It I t I t I t I HI HI
— — — — — — — — — — — — — — —
45 1 1 11 1 1 111WHIMI I fthuff a Lela-5113�7100 isf
— — — — — — — — — — — — — — —
40 IH 1 14 1 1 1 _�_I HI H�Lq offVnIqr p=3-6iO 11_paf
3 35 H H H H H%norI�e1h1=3:. 30 OW' en }hamn/ •1LV G ■ SL �jLV
25 I I I I I I I I I I I I I I I I I I II I I ICI ���I�
20 1-LIHI-LILI HI HI H H IH U Ht-W
15
10
+ IHIHIHIHI HI HI HI H IH IH IH IHIHI
5 I,II 71III11111111111111-1 111111
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
■ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 17
Summary for Subcatchment 108S: Area draining to 102
Runoff = 118.38 cfs @ 12.01 hrs, Volume= 6.481 af, Depth= 3.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf) CN Description
924,571 80 Final Cover
924,571 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
6.6 100
0.0500
0.25
Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
3.1 650
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fDs
9.7 750 Total, Increased to minimum Tc = 10.0 min
13
12
11
10
Subcatchment 108S: Area draining to 102
Hydrograph
- - I -I -M M M _7 I—T 7 -7I 7
118.38 CfS ❑Runoff
III J- I �-I �-I
Ou
70
I�
3
I-
60
.°
50
40
30
20
10
ar ain
i l t l t l t l t-1 �1 -RWr off Ar*a=92145711 Jsf
�De h-��unl�f
1W ILen� th=. 50l
I- T I T I � 1 F1 F-1 I7 1-7 7 ITT LT .6nj
IIIIIIIIIIIIIIIIII11111tk�="
�I+I+1-HH H H I-tI4I4I+II-�-.11
L�I11111111111111111111111111
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 18
Summary for Subcatchment 201S: DA 201
Area that drains using HydroCAD catchmentarea +38.75 acres to the southwest of the basin by the pond
Runoff = 293.94 cfs @ 12.22 hrs, Volume= 27.607 af, Depth= 2.89"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf)
CN
Description
899,000
60
Woods
1,250,000
75
Residential
2,239,000
74
>75% Grass cover, Good, HSG C
610,000
80
Final Cover
4,998,000
72
Weighted Average
4,998,000
100.00% Pervious Area
Tc
(min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(cfs)
20.8
100
0.0200
0.08
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.41"
3.5
150
0.0200
0.71
Shallow Concentrated Flow, shallow
Woodland Kv= 5.0 fps
4.4
500
0.0740
1.90
Shallow Concentrated Flow, shallow
Short Grass Pasture Kv= 7.0 fps
28.7 750 Total

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 19
Subcatchment 201 S: DA 201
Hydrograph
320
I� rt
14 1� 1
-T—I
� I
� I
H
I
i r I+ 14-1
❑Runoff
30o
300
293.94
cfs �
�
�
�
�
�
� � � -L I l �
I 1I�
260
TI
�I
�I
I�
T P I -fill`
15LeWF�arifi=�J8t
240
I� �
� I � I
� I
�I
�I
�I
I�ulpl�#�°►�"��f��I�Q �#
220AL
200
_
_ 1
J- I
t-I
�-I
_
-�rfTjv l �u r 1-7
180
160
T
T
T
-I
-I
I-
97
I- R-- = I -ii l
0
_
i�h
LL 140
t I
t I
t l
-I
H
1-t I 11�d=
120
100
4-1
-kI
�I
1-4 14 4 14- 14- P�=T�
80
60
I11
TIT
I
1111111111111111'
40
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 20
Summary for Subcatchment 202S: DA 202
Area that drains using HydroCAD catchmentarea +38.75 acres to the southwest of the basin by the pond
Runoff = 120.15 cfs @ 12.16 hrs, Volume= 9.783 af, Depth= 2.79"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf) CN DescriDtion
620,000
60 Woods, Fair, HSG B
570,000
74 >75% Grass cover, Good, HSG C
640,000
80 Final Cover
1,830,000
71 Weighted Average
1,830,000
100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
20.8 100
0.0200
0.08
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.41"
2.0 300
0.2500
2.50
Shallow Concentrated Flow, shallow
Woodland Kv= 5.0 fps
22.8 400 Total
Subcatchment 202S: DA 202
Hydrograph
�ITIT
T
�I
�I
I�
I-4 1- TT T �I
1301/1120.15
120
fl-
cfs
T
T
T
T
I
T Tp+�_1,
110
1
L 1
LI
LI
LI
-�5�y�Okal 6fAk-�.18t
100
T I
T I
�-I
Ruin-o"r"F-I-'OAQOQ 0
80
11
hl��'�-g'1�
70
Runoff Depth--�3.79"
T
1o, 6en6ih 460
60
50
4030
H
1-4 1+4-I�-II
20
10
1 1
11
TI
TI
TI
IT
IT IT T I T TI TI TI
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Runoff

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type // 24-hr 25-year Rainfall=5.87"
Printed 1/15/2020
HvdroCAD®10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Paae 21
Summary for Subcatchment 203S: DA 203
Runoff = 56.45 cfs @ 12.07 hrs, Volume= 3.531 af, Depth= 3.08"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf) CN Description
600,000 74 >75% Grass cover, Good, HSG C
600,000 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
9.5
100
0.0200
0.18
Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
2.5
150
0.0200
0.99
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.8
200
0.3333
4.04
Shallow Concentrated Flow, shallow
Short Grass Pasture Kv= 7.0 fps
1.4
250
0.1800
2.97
Shallow Concentrated Flow, shallow
Short Grass Pasture Kv= 7.0 fDs
14.2 700 Total
Subcatchment 203S: DA 203
Hydrograph
so
56.45
55
50
TI
-TITITITIT
45
IIIIII
IIIIIIIII
40
I -I
4IIIIT
w 35
I�
rt Irtlrtl�lT
_;30
"25
20
j 14 1 1T1-
15
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10
54/1
I
TI H H H I-1
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I I I fth6ff a tela�--60%0100 isf
TI � ttgoff��3f 31
- �I -I�jjr,Riep�h=-�.n"
law Le!�-� tl 0o
( I I I I I I I I I I�c�41
TI �-I �-j I-1 I-1 "
TI t-I tI N I-1 I-t It it I
III "IF (IIIIIIIIT'
14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
■ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 22
Summary for Subcatchment 204S: RAB Landfill Area
Runoff = 239.25 cfs @ 12.02 hrs, Volume= 12.946 af, Depth= 3.08"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-year Rainfall=5.87"
Area (sf) CN Description
2,200,000 74 Pasture/grassland/range, Good, HSG C
2,200,000 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.5 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
9.5 100 Total, Increased to minimum Tc = 10.0 min
Subcatchment 204S: RAB Landfill Area
Hydrograph
260
240
239.25 cfs
1
T I
T I
T I
T-I
1I
I
220
I
I I
L
LI
L1
145� y66""f�li =1�-J&t
�
u"Y1' 1 `� ����099 0
180
160
1
1 1 1
1 1
1 1
1 1
1 1
I�ulrri°�o` 1 7T 2I- 1 11
`= 140RunoffD"
�
_ 00"
� L�e1n i�h='�
LL 120
100
fi
fil
�I
r1
I-1 1- Irt Mope=�b1010�
80
1 1 Tc1=19.9 O n
60
�I
H
1-4 1 4 1 + 1 4- F 1-
40
20
I�LT
T
T
�I
�I
I7 I� T T T l it
0 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68
Time (hours)
❑ Runoff

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type // 24-hr 25-year Rainfall=5.87"
Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC
Summary for Reach 102R: Ditch 102
[62] Hint: Exceeded Reach 106R OUTLET depth by 0.79' @ 12.05 hrs
[62] Hint: Exceeded Reach 109R OUTLET depth by 1.42' @ 12.21 hrs
Inflow Area = 155.968 ac, 0.00% Impervious, Inflow Depth = 2.94" for 25-year event
Inflow = 454.15 cfs @ 12.05 hrs, Volume= 38.267 of
Outflow = 392.71 cfs @ 12.12 hrs, Volume= 38.267 af, Atten= 14%, Lag= 4.5 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 5.94 fps, Min. Travel Time= 6.7 min
Avg. Velocity = 1.24 fps, Avg. Travel Time= 32.3 min
Peak Storage= 158,610 cf @ 12.12 hrs
Average Depth at Peak Storage= 1.86'
Bank -Full Depth= 4.50' Flow Area= 195.8 sf, Capacity= 1,916.64 cfs
30.00' x 4.50' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 57.00'
Length= 2,400.0' Slope= 0.0054 T
Inlet Invert= 608.00', Outlet Invert= 595.00'

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 24
Reach 102R: Ditch 102
Hydrograph
0
I�Ifilfil17I
454.15 cfs
HI-tIT
TI
Li I—�Ifilfilfilt-I
■ Inflow
■outflow
48
H
H
I4
14 + 1
�
460
ago
392.71 cfs
:FI
F]
I-T
IT T I
A�r j.]
400
360
�I
b
I-t
I - -r1
�1 n "��5�4
30 34
320
1
H
H
I-1
It t I
t-I H I- - t
300
3 26o
I
�--I
H
I-+
14 1
-1 H H-+
240
LL 220
-
-I
Q
I-
- 7-�a
a �i 1 19
—
180
I� �1
LI
t-
I--L
I- t 1
LI Ll Ll I-L I I I t1 L
140
120
100
-
H
-
- -
- 1-� - - - - -
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 25
Summary for Reach 104: Ditch 104
Inflow Area = 28.108 ac, 0.00% Impervious, Inflow Depth = 3.66" for 25-year event
Inflow = 137.58 cfs @ 12.06 hrs, Volume= 8.583 of
Outflow = 118.45 cfs @ 12.12 hrs, Volume= 8.583 af, Atten= 14%, Lag= 3.7 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 3.65 fps, Min. Travel Time= 7.1 min
Avg. Velocity = 0.81 fps, Avg. Travel Time= 32.0 min
Peak Storage= 50,290 cf @ 12.12 hrs
Average Depth at Peak Storage= 0.77'
Bank -Full Depth= 4.00' Flow Area= 208.0 sf, Capacity= 2,039.57 cfs
40.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 64.00'
Length= 1,550.0' Slope= 0.0058 T
Inlet Invert= 588.00', Outlet Invert= 579.00'
Reach 104: Ditch 104
Hydrograph
150
1408.�68�c
i- � �
137.58 cfs -
❑Inflow
❑ outflow
130CI118.45
cfs _1 F _1 IT
120
110
14 4-1 H H 14 1 �-lak Vei1*3.65 fosl
100
l L 1 LI 1-1 IL I L L I L I L IL I L Leh=a.2251
90
80
— �I n Irt rt LI �_l rt rt
" 60
/
I- H I4 14 L 1 - It I �I TI005 1 �1
50
fit
Capaci,�9� '�1 �lnf sl
40
30
. rtIt TIfi1 1 1- rtITIfiI tl
i
it
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type // 24-hr 25-year Rainfall=5.87"
Printed 1/15/2020
HvdroCAD®10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Paae 26
Summary for Reach 106R: Ditch 106
Inflow Area = 81.911 ac, 0.00% Impervious, Inflow Depth = 2.79" for 25-year event
Inflow = 226.60 cfs @ 12.18 hrs, Volume= 19.074 of
Outflow = 217.35 cfs @ 12.23 hrs, Volume= 19.074 af, Atten= 4%, Lag= 2.9 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 4.71 fps, Min. Travel Time= 4.3 min
Avg. Velocity = 1.16 fps, Avg. Travel Time= 17.4 min
Peak Storage= 55,779 cf @ 12.23 hrs
Average Depth at Peak Storage= 1.35'
Bank -Full Depth= 4.50' Flow Area= 195.8 sf, Capacity= 1,833.82 cfs
30.00' x 4.50' deep channel, n= 0.025
Side Slope Z-value= 3.0 7' Top Width= 57.00'
Length= 1,210.0' Slope= 0.0050 T
Inlet Invert= 614.00', Outlet Invert= 608.00'
21
14
13
0 12
LL 11
Id
Reach 106R: Ditch 106
Hydrograph
226.6o cfs 1
217.35 cfs H H .61 1H�(
I �-I H I-4 1 4- Ij��'L ilW� jo�-_
�I�Ial�l�
HI
HI
H
IH
IH
�I
H
H
I4
1�
_T
_F1
771
H
I_T
IT
�
- IHIHIHIH
9•
hllaHxl 514.1 plc
H I H I
H IH H 1 +0=�Q-R �
4- �IH
IHI4�€j�
T I T1
H IH 1-g111�1�
HI+-IHIHIHIHIHIH
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
■ Inflow
■ outflow

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 27
Summary for Reach 107Ra: Ditch 107_Shallow
Inflow Area = 77.188 ac, 0.00% Impervious, Inflow Depth = 3.16" for 25-year event
Inflow = 261.46 cfs @ 12.08 hrs, Volume= 20.350 of
Outflow = 254.49 cfs @ 12.10 hrs, Volume= 20.350 af, Atten= 3%, Lag= 1.6 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 5.55 fps, Min. Travel Time= 2.6 min
Avg. Velocity = 1.31 fps, Avg. Travel Time= 11.1 min
Peak Storage= 39,917 cf @ 12.10 hrs
Average Depth at Peak Storage= 1.35'
Bank -Full Depth= 4.00' Flow Area= 168.0 sf, Capacity= 1,739.55 cfs
30.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 7' Top Width= 54.00'
Length= 870.0' Slope= 0.0069 7'
Inlet Invert= 628.00', Outlet Invert= 622.00'
Reach 107Ra: Ditch 107 Shallow
Hydrograph
280
F261.46
254.49
H❑
cfs TI T T I T 1 I� 1❑
rl-
cfs�PP—C
Inflow
outflow
260
240
HI H IH 1
220
rlllax dell �.55 f0s1
200
18o
H
H H H H H H I H HI H H I +0=:Q.M
160
J H IL I L I LI L 11 IL I _LLI F"�1
LL 120
N Irt I t fi I fit fi 1010pp?-�,�
180
---�1
a-1 HI H I I � '?�CI'7 5S
60
`1 71 T T IT T I T I T IH T IT T I HI 1
40
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type // 24-hr 25-year Rainfall=5.87"
Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC
Summary for Reach 107Rb: Ditch 107_Steep
[61] Hint: Exceeded Reach 107Ra outlet invert by 0.73' @ 12.11 hrs
Inflow Area = 77.188 ac, 0.00% Impervious, Inflow Depth = 3.16" for 25-year event
Inflow = 254.49 cfs @ 12.10 hrs, Volume= 20.350 of
Outflow = 253.84 cfs @ 12.11 hrs, Volume= 20.350 af, Atten= 0%, Lag= 0.6 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 10.85 fps, Min. Travel Time= 0.9 min
Avg. Velocity = 2.69 fps, Avg. Travel Time= 3.5 min
Peak Storage= 13,333 cf @ 12.11 hrs
Average Depth at Peak Storage= 0.73'
Bank -Full Depth= 4.00' Flow Area= 168.0 sf, Capacity= 4,963.15 cfs
30.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 54.00'
Length= 570.0' Slope= 0.0561 T
Inlet Invert= 622.00', Outlet Invert= 590.00'
E9

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 29
Reach 107Rb: Ditch 107_Steep
Hydrograph
280
I-r I T-I 1 1 I-T 17 7 I 1 1 1 1 1 1 1 1 1 T 1
■ Inflow
■outflow
260
253.84
cfs LU� T L 1 I ii8la
li> 111 iv �►ri"e
.
240
fi N I t t *4 AFi�ni�e--p-L-1�
20
1 1 1 MeikV-W .95 f0sl
200
18oZ.
-i
- 7 T fiI 1- 7 Tm•45
160
u-1 14 T I t-I I- 7 I
3 140
LL 120
1
1 TI n 7 I T T I T F1 I-t Y
180
1
--IsI`�111,11f5p1--
1�I N Inc I�'T �ls
60
T 1 71 I -I I7 IT 1 T 1 T 1 71 1- 7 IT I T I F
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 30
Summary for Reach 109R: Ditch 105
Inflow Area = 21.225 ac, 0.00% Impervious, Inflow Depth = 3.66" for 25-year event
Inflow = 118.38 cfs @ 12.01 hrs, Volume= 6.481 of
Outflow = 116.03 cfs @ 12.03 hrs, Volume= 6.481 af, Atten= 2%, Lag= 1.1 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 8.82 fps, Min. Travel Time= 1.8 min
Avg. Velocity = 2.09 fps, Avg. Travel Time= 7.6 min
Peak Storage= 12,488 cf @ 12.03 hrs
Average Depth at Peak Storage= 0.66'
Bank -Full Depth= 4.00' Flow Area= 120.0 sf, Capacity= 2,959.13 cfs
18.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 7' Top Width= 42.00'
Length= 950.0' Slope= 0.0442 T
Inlet Invert= 650.00', Outlet Invert= 608.00'
Reach 109R: Ditch 105
Hydrograph
130 118.38 cfs
120 116.03 cfs 1 }il" 1A1 r"1: AI cl_
110 14 T--
100IT TI TIT 1 T T T TM-a7x Vdl*8.8_2 0sl
90
80 ! ! ! �I I� rhl•51
6011 1 x A A 11 l j 1 —S,=�0
50 Capacity=2,959.13 c#s,
40 HIHIHI-I
30 Illi IIIIIIIIII �IIIII
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Inflow
❑ outflow

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 31
Summary for Reach 206Ra: Channel 201
Inflow Area = 114.738 ac, 0.00% Impervious, Inflow Depth = 2.89" for 25-year event
Inflow = 293.94 cfs @ 12.22 hrs, Volume= 27.607 of
Outflow = 278.61 cfs @ 12.30 hrs, Volume= 27.607 af, Atten= 5%, Lag= 4.6 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 5.15 fps, Min. Travel Time= 5.8 min
Avg. Velocity = 1.46 fps, Avg. Travel Time= 20.6 min
Peak Storage= 97,327 cf @ 12.30 hrs
Average Depth at Peak Storage= 1.56'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,724.30 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 7' Top Width= 90.00'
Length= 1,800.0' Slope= 0.0050 '/'
Inlet Invert= 598.00', Outlet Invert= 589.00'
Reach 206Ra: Channel 201
Hydrograph
320
300
I I
293.94
I I I I I I I I I I I I I I I I I I I I 1
cfs -1
❑ Inflow
❑outflow
280
278.61
cfs
1 1 1 11 1 1 1 1 1 11 A�6_1016"l le fft=1 �561
260
240
�--1 n Irt I rt -r I fiI �-1 "Otl--545 fps-
220
200
14
HHH1++1-1HHI-fI+� �
180
160
14 1
�I N I-4 1 4-1 �1 1-4I� 11�0 .`
5 /
0
LL 140
l
—o.i-
LI Ll H _1 1- 11 1£ � Ig17124136J
120
100
1 1
r I T-1 n I-T IT Ti T_ 1�_l 1_ I I T I_r I rI
80
60
1 _�_l H it t t 1 tl ti 1--f _t I t I t1 H 1]
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Paae 32
Summary for Reach 206Rb: Channel 201
[62] Hint: Exceeded Reach 107Rb OUTLET depth by 0.66' @ 12.30 hrs
[62] Hint: Exceeded Reach 206Ra OUTLET depth by 1.06' @ 12.08 hrs
Inflow Area = 242.432 ac, 0.00% Impervious, Inflow Depth = 3.01" for 25-year event
Inflow = 571.87 cfs @ 12.08 hrs, Volume= 60.902 of
Outflow = 528.74 cfs @ 12.19 hrs, Volume= 60.902 af, Atten= 8%, Lag= 6.6 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 6.36 fps, Min. Travel Time= 6.4 min
Avg. Velocity = 1.67 fps, Avg. Travel Time= 24.3 min
Peak Storage= 202,085 cf @ 12.19 hrs
Average Depth at Peak Storage= 2.26'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,670.28 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 90.00'
Length= 2,430.0' Slope= 0.0049 T
Inlet Invert= 589.00', Outlet Invert= 577.00'

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 33
Reach 206Rb: Channel 201
Hydrograph
I I I I I I I I
571.87 Cfs
I I
I I
I I I I I I I I I I I I I I I I I I I I
i outf oW
550
528.74 Cfs rI
F-I
I7
1 T T I
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400
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IIIIIIIIIIIIIIIIIIIIIIIIIIII
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type // 24-hr 25-year Rainfall=5.87"
Printed 1/15/2020
HvdroCAD®10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC
Summary for Reach 207R: Channel 202
Inflow Area = 42.011 ac, 0.00% Impervious, Inflow Depth = 2.79" for 25-year event
Inflow = 120.15 cfs @ 12.16 hrs, Volume= 9.783 of
Outflow = 111.86 cfs @ 12.23 hrs, Volume= 9.783 af, Atten= 7%, Lag= 3.9 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 3.73 fps, Min. Travel Time= 5.8 min
Avg. Velocity = 1.12 fps, Avg. Travel Time= 19.3 min
Peak Storage= 38,932 cf @ 12.23 hrs
Average Depth at Peak Storage= 0.91'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,724.30 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 90.00'
Length= 1,300.0' Slope= 0.0050 T
Inlet Invert= 590.00', Outlet Invert= 583.50'
Reach 207R: Channel 202
Hydrograph
130
120.15 cfs T
120
111.86 cfsI
110
100
L
90
1 LI L IL
80
N
70
3
60
E
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Inflow
❑ outflow

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type // 24-hr 25-year Rainfall=5.87"
Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC
Summary for Reach 208R: Channel 202
[62] Hint: Exceeded Reach 207R OUTLET depth by 0.15' @ 12.09 hrs
Inflow Area = 55.785 ac, 0.00% Impervious, Inflow Depth = 2.86" for 25-year event
Inflow = 143.68 cfs @ 12.17 hrs, Volume= 13.313 of
Outflow = 138.94 cfs @ 12.22 hrs, Volume= 13.313 af, Atten= 3%, Lag= 3.4 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 4.04 fps, Min. Travel Time= 4.5 min
Avg. Velocity = 1.20 fps, Avg. Travel Time= 15.3 min
Peak Storage= 37,837 cf @ 12.22 hrs
Average Depth at Peak Storage= 1.04'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,724.30 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 7' Top Width= 90.00'
Length= 1,100.0' Slope= 0.0050 T
Inlet Invert= 583.50', Outlet Invert= 578.00'
E9

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 36
Reach 208R: Channel 202
Hydrograph
150
150
143.68
138.94
I I I I I I I I I I I I I I I I I I I I I I I I I I I I
cfs H H H I H H 1 H
Iilc�i�v Aria-55.85
Inflow
■ outflow
arc
Cfs140
130
TIN I� T IA�g�ioW-b -
120
_III l l l l l l l l l l 1 1 c l Vd 1 4.04 fplsl
110
100
-
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60
50
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40
30
1
i t1 N I fi fi I fi 1 1� I� I fi l fi I �I
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 37
Summary for Pond 10OP: SE Detention Option 1
Keeping pond below 25 feet in height and 50 acre-feet of storage to avoid dam classification
Inflow Area = 215.660 ac, 0.00% Impervious, Inflow Depth = 3.14" for 25-year event
Inflow = 643.02 cfs @ 12.09 hrs, Volume= 56.493 of
Outflow = 61.30 cfs @ 13.50 hrs, Volume= 57.339 af, Atten= 90%, Lag= 84.4 min
Primary = 61.30 cfs @ 13.50 hrs, Volume= 57.339 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 567.00' Surf.Area= 110,000 sf Storage= 36,667 cf
Peak Elev= 576.13' @ 13.50 hrs Surf.Area= 148,908 sf Storage= 1,214,565 cf (1,177,898 cf above start)
Plug -Flow detention time= (not calculated: outflow precedes inflow)
Center -of -Mass det. time= 222.2 min ( 1,071.2 - 849.0 )
Volume Invert Avail.Storage Storage Description
#1 566.00' 2,169,341 cf Custom Stage Data (Irregular)Listed below (Recalc)
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq-ft) (feet) (cubic -feet) (cubic -feet) (sq-ft)
566.00 0 0.0 0 0 0
567.00 110,000 1,340.0 36,667 36,667 142,891
582.00 177,000 1,630.0 2,132,675 2,169,341 214,960
Device Routing Invert Outlet Devices
#1 Primary 566.00' 20.0" Round Culvert X 2.00
L= 100.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 566.00' / 565.00' S= 0.0100 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 2.18 sf
#2 Secondary 581.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 5.00
Width (feet) 50.00 56.00 80.00
Primary OutFlow Max=61.30 cfs @ 13.50 hrs HW=576.13' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Barrel Controls 61.30 cfs @ 14.05 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=567.00' TW=565.70' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Page 38
Pond 100P: SE Detention Option 1
Hyydrograph
I-
I+ I
H
1
I� I- H I+ I
■ Inflow
643.02
cfs
I J-I
14
� I
4-1
I+�jl" � � $.
� outflow
700
Secondary
650
T
I� TI
T
I� TFI� ��'1
550
500
450
/
�400
0 350
I� I
I t I
t�
II H I t I H ff fil
LL 300
_fiI
_fiI
250
/
I �-I
4
I I
I4 14-I k4 I-� I 14 I -P
200
an f1fq
150Al
61.30 cfs
IIII
IIII
IIII IIII Ili
0.00 cfs
0 2 4 6 8 1012141618 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 39
Summary for Pond 103P: SW Detention Option 2
Keeping pond below 25 feet in height and 50 acre-feet of storage to avoid dam classification
Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Outflow = 4.65 cfs @ 0.00 hrs, Volume= 0.530 af, Atten= 0%, Lag= 0.0 min
Primary = 4.65 cfs @ 0.00 hrs, Volume= 0.530 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 566.00' Surf.Area= 105,000 sf Storage= 35,000 cf
Peak Elev= 566.00' @ 0.00 hrs Surf.Area= 105,000 sf Storage= 35,000 cf
Plug -Flow detention time= (not calculated: initial storage exceeds outflow)
Center -of -Mass det. time= (not calculated: no inflow)
Volume Invert Avail.Storage Storage Description
#1 565.00' 2,989,805 cf Custom Stage Data (Irregular)Listed below (Recalc)
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq-ft) (feet) (cubic -feet) (cubic -feet) (sq-ft)
565.00 0 0.0 0 0 0
566.00 105,000 1,310.0 35,000 35,000 136,564
581.00 170,000 1,600.0 2,043,019 2,078,019 207,177
586.00 195,000 1,690.0 911,786 2,989,805 232,135
Device Routing Invert Outlet Devices
#1 Primary 565.00' 20.0" Round Culvert X 2.00
L= 100.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 565.00' / 564.00' S= 0.0100 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 2.18 sf
#2 Secondary 585.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 5.00
Width (feet) 50.00 56.00 80.00
Primary OutFlow Max=4.65 cfs @ 0.00 hrs HW=566.00' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Outlet Controls 4.65 cfs @ 2.44 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=566.00' TW=565.70' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 40
Pond 103P: SW Detention Option 2
Hydrograph
Ill i� l--� l 4-1 � l 4- l -i l-4 l14 l �-4 l�
71Miiiiiiiiii1111i�t6�r666I:=i3151,666Id
+ I H Wi-I H I+ I -H I-iI+I H IC I+ -I H
0 2 4 6 8 1012 1416 18 20 22 24 2628 30 32 34 36 38 40 42 4446 48 50 52 54 56 58 60 6264 66 68 70 72
Time (hours)
■ Inflow
❑ Outflow
❑ Primary
■ Secondary

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 41
Summary for Pond 104P: NE Detention Option 1 - Pond 1
Keeping pond below 25 feet in height and 50 acre-feet of storage to avoid dam classification
Inflow Area = 298.217 ac, 0.00% Impervious, Inflow Depth = 2.99" for 25-year event
Inflow = 666.63 cfs @ 12.20 hrs, Volume= 74.216 of
Outflow = 201.18 cfs @ 12.88 hrs, Volume= 74.973 af, Atten= 70%, Lag= 40.6 min
Primary = 201.18 cfs @ 12.88 hrs, Volume= 74.973 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 567.00' Surf.Area= 98,000 sf Storage= 32,667 cf
Peak Elev= 576.24' @ 12.88 hrs Surf.Area= 136,074 sf Storage= 1,108,735 cf (1,076,068 cf above start)
Plug -Flow detention time= (not calculated: outflow precedes inflow)
Center -of -Mass det. time= 55.8 min ( 919.2 - 863.4 )
Volume Invert Avail.Storage Storage Description
#1 566.00' 5,085,589 cf Custom Stage Data (Irregular)Listed below (Recalc)
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq-ft) (feet) (cubic -feet) (cubic -feet) (sq-ft)
566.00 0 0.0 0 0 0
567.00 98,000 1,310.0 32,667 32,667 136,564
582.00 163,000 1,600.0 1,936,941 1,969,608 207,177
601.00 165,000 1,610.0 3,115,981 5,085,589 237,779
Device Routing Invert Outlet Devices
#1 Primary 566.00' 36.0" Round Culvert X 2.00
L= 100.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 566.00' / 565.00' S= 0.0100 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 7.07 sf
#2 Secondary 581.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 5.00 20.00
Width (feet) 50.00 56.00 80.00 80.00
Primary OutFlow Max=201.18 cfs @ 12.88 hrs HW=576.24' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Inlet Controls 201.18 cfs @ 14.23 fps)
te2
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=567.00' TW=565.70' (Dynamic Tailwater)
=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 42
Pond 104P: NE Detention Option 1 - Pond 1
Hydrograph
/
I Illllllllli��llii�li�l�ll_
661 cfs I fit
fi
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700
I+1
I41 +-I
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1414-FORV�' M� 241
650
j
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-600
I� 1 J-1
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550
�
IIIII
IIIIIIIIIIIIIIIIIIIIIIIIII
_
500
450
400
rt
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rt
I rt 11-1
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350
u_
qni 1
R
300
250
201.1cfs 8 I�
�
1 � I
"
j I � I I-4 � I �--I 1� I
200
/
III
IIII
IIII IIII III
150
/
100
0.06 cfs
/
0 2 4 6 8 1012141618 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
■ In
7 Outflow
❑ Primary
i Secondary

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 43
Summary for Pond 107P: East SW Detention Option 3
Keeping pond below 25 feet in height and 50 acre-feet of storage to avoid dam classification
Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Outflow = 3.12 cfs @ 0.00 hrs, Volume= 0.529 af, Atten= 0%, Lag= 0.0 min
Primary = 3.12 cfs @ 0.00 hrs, Volume= 0.529 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 566.00' Surf.Area= 105,000 sf Storage= 35,000 cf
Peak Elev= 566.00' @ 0.00 hrs Surf.Area= 105,000 sf Storage= 35,000 cf
Plug -Flow detention time= (not calculated: initial storage exceeds outflow)
Center -of -Mass det. time= (not calculated: no inflow)
Volume Invert Avail.Storage Storage Description
#1 565.00' 2,078,019 cf Custom Stage Data (Irregular)Listed below (Recalc)
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq-ft) (feet) (cubic -feet) (cubic -feet) (sq-ft)
565.00 0 0.0 0 0 0
566.00 105,000 1,310.0 35,000 35,000 136,564
581.00 170,000 1,600.0 2,043,019 2,078,019 207,177
Device Routing Invert Outlet Devices
#1 Primary 565.00' 30.0" Round Culvert
L= 100.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 565.00' / 564.00' S= 0.0100 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 4.91 sf
#2 Secondary 580.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 5.00
Width (feet) 50.00 56.00 80.00
Primary OutFlow Max=3.12 cfs @ 0.00 hrs HW=566.00' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Outlet Controls 3.12 cfs @ 2.52 fps)
te2
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=566.00' TW=565.70' (Dynamic Tailwater)
=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Page 44
3.12 cfs
3
w 2
u
3
0
LL
1-
0.0
0.00 cfs
Pond 107P: East SW Detention Option 3
Hydrograph
i i l i l i i l i l l i l i i i i l i i l i l i i l i l I
I I I I I I I I I I I I I I I I I I�tb�rag�e��315I,bbb ICf
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
IIIIIIIIIIIIIIIIIIIIIIIIIIII
0 2 4 6 8 1012 1416 18 20 22 24 2628 30 32 34 36 38 40 42 4446 48 50 52 54 56 58 60 6264 66 68 70 72
Time (hours)
■ Inflow
❑ Outflow
❑ Primary
■ Secondary

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type // 24-hr 25-year Rainfall=5.87"
Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC
Summary for Pond 108P: RAB Ex. Spillway (no storage)
[43] Hint: Has no inflow (Outflow=Zero)
Device
Routing
Invert
Outlet Devices
#1
Primary
611.00'
42.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 611.00' / 606.00' S= 0.1000 '/' Cc= 0.900
n= 0.012, Flow Area= 9.62 sf
#2
Secondary
618.90'
Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 5.00
Width (feet) 20.00 60.00
#3
Tertiary
624.25'
Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 5.00
Width (feet) 200.00 200.00
Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' TW=565.70' (Dynamic Tailwater)
L1=Culvert ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' TW=565.70' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)
Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' (Free Discharge)
L3=Custom Weir/Orifice ( Controls 0.00 cfs)
Pond 108P: RAB Ex. Spillway (no storage)
Hydrograph
❑ Primary
❑ Secondary
■ Tertiary
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Paae 46
Summary for Pond 200: RAB Outlet Pond (no storage)
[43] Hint: Has no inflow (Outflow=Zero)
Device Routing Invert Outlet Devices
#1 Primary
570.20' 36.0" Round RCP Culvert
L= 114.3' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 570.20' / 566.40' S= 0.0332 '/' Cc= 0.900
n= 0.012 Concrete pipe, finished, Flow Area= 7.07 sf
#2 Device 1
606.12' 42.0" Round 42" Culvert Steep
L= 56.3' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 606.12' / 570.20' S= 0.6380 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 9.62 sf
#3 Device 2
609.10' 42.0" Round 42" Culvert Shallow
L= 27.3' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 609.10' / 606.12' S= 0.1092 '/' Cc= 0.900
n= 0.013, Flow Area= 9.62 sf
#4 Device 3
611.09' 54.0" Round 54" Culvert
L= 20.5' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 611.09' / 609.10' S= 0.0971 T Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 15.90 sf
#5 Secondary
618.90' Emergency Spillway, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 5.25
Width (feet) 20.00 28.00 36.00 44.00 52.00 60.00 60.00
#6 Tertiary
624.25' 260.0' long x 40.0' 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) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' TW=565.70' (Dynamic Tailwater)
L1=RCP Culvert ( Controls 0.00 cfs)
L2=42" Culvert Steep ( Controls 0.00 cfs)
Lt42" Culvert Shallow ( Controls 0.00 cfs)
4=54" Culvert ( Controls 0.00 cfs)
te5
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' TW=565.70' (Dynamic Tailwater)
=Emergency Spillway ( Controls 0.00 cfs)
Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' TW=565.70' (Dynamic Tailwater)
L6=Broad-Crested Rectangular Weir( Controls 0.00 cfs)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type/1 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD®10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 47
Pond 200: RAB Outlet Pond (no storage)
Hydrograph
N Primary
1 i Secondary
■ Tertiary
I�eail� E���v-b.bb
3
0
LL
0.00 Cfs
0
0 2 4 6 8 10 1214 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Paae 48
Summary for Link 102L: Lake Wylie/Catawba River
Inflow Area = 215.660 ac, 0.00% Impervious, Inflow Depth = 3.25" for 25-year event
Inflow = 61.30 cfs @ 13.50 hrs, Volume= 58.398 of
Primary = 61.30 cfs @ 13.50 hrs, Volume= 58.398 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Fixed water surface Elevation= 565.70'
Link 102L: Lake Wylie/Catawba River
Hydrograph
i—I
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+ Ian 16' �A rel- =ii �-. O6"c
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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Inflow
❑ Primary

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 49
Summary for Link 104L: Lake Wylie/Catawba River
Inflow Area = 298.217 ac, 0.00% Impervious, Inflow Depth = 3.02" for 25-year event
Inflow = 201.18 cfs @ 12.88 hrs, Volume= 74.973 of
Primary = 201.18 cfs @ 12.88 hrs, Volume= 74.973 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Fixed water surface Elevation= 565.70'
Link 104L: Lake Wylie/Catawba River
Hydrograph
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❑Primary
210
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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 50
Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points x 3
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method
Subcatchment 102S: DA 102 Runoff Area=2,301,379 sf 0.00% Impervious Runoff Depth=4.16"
Flow Length=850' Tc=10.2 min CN=72 Runoff=335.39 cfs 18.331 of
Subcatchment 103S: DA 103 Runoff Area=1,375,819 sf 0.00% Impervious Runoff Depth=5.06"
Flow Length=1,200' Tc=11.8 min CN=80 Runoff=225.62 cfs 13.307 of
Subcatchment 104S: Area Draining to 104 Runoff Area=1,224,363 sf
0.00% Impervious Runoff Depth=5.06"
Flow Length=1,000' Tc=13.9 min
CN=80 Runoff=187.79 cfs 11.842 of
Subcatchment 105Sa: Area draining to 105 Runoff Area=914,000 sf
0.00% Impervious Runoff Depth=5.06"
Flow Length=2,150' Tc=32.6 min CN=80 Runoff=86.86 cfs 8.840 of
Subcatchment 106S: DA 106 Runoff Area=3,568,027 sf
0.00% Impervious Runoff Depth=4.05"
Flow Length=1,935' Tc=24.2 min
CN=71 Runoff=330.94 cfs 27.672 of
Subcatchment107Sa: Northwest AAB Runoff Area=1,934,630 sf
0.00% Impervious Runoff Depth=4.05"
Flow Length=1,050' Tc=14.1 min
CN=71 Runoff=240.21 cfs 15.004 of
Subcatchment 107Sb: NW of North face of Runoff Area=513,700 sf
0.00% Impervious Runoff Depth=5.06"
Flow Length=1,050' Tc=14.1 min CN=80 Runoff=78.21 cfs 4.968 of
Subcatchment 108S: Area draining to 102 Runoff Area=924,571 sf
0.00% Impervious Runoff Depth=5.06"
Flow Length=750' Tc=10.0 min
CN=80 Runoff=161.21 cfs 8.942 of
Subcatchment201 S: DA 201 Runoff Area=4,998,000 sf 0.00% Impervious Runoff Depth=4.16"
Flow Length=750' Tc=28.7 min CN=72 Runoff=427.16 cfs 39.810 of
Subcatchment202S: DA 202 Runoff Area=1,830,000 sf 0.00% Impervious Runoff Depth=4.05"
Flow Length=400' Tc=22.8 min CN=71 Runoff=175.42 cfs 14.193 of
Subcatchment203S: DA 203 Runoff Area=600,000 sf 0.00% Impervious Runoff Depth=4.38"
Flow Length=700' Tc=14.2 min CN=74 Runoff=80.07 cfs 5.032 of
Subcatchment204S: RAB Landfill Area Runoff Area=2,200,000 sf 0.00% Impervious Runoff Depth=4.38"
Flow Length=100' Slope=0.0200 '/' Tc=10.0 min CN=74 Runoff=338.55 cfs 18.451 of
Reach 102R: Ditch 102 Avg. Flow Depth=2.34' Max Vet=6.79 fps Inflow=660.68 cfs 54.945 of
n=0.025 L=2,400.0' S=0.0054 '/' Capacity=1,916.64 cfs Outflow=587.28 cfs 54.945 of
Reach 104: Ditch 104 Avg. Flow Depth=0.94' Max Vet=4.14 fps Inflow=187.79 cfs 11.842 of
n=0.025 L=1,550.0' S=0.0058 '/' Capacity=2,039.57 cfs Outflow=166.22 cfs 11.842 of
Reach 106R: Ditch 106 Avg. Flow Depth=1.69' Max Vet=5.39 fps Inflow=330.94 cfs 27.672 of
n=0.025 L=1,210.0' S=0.0050 '/' Capacity=1,833.82 cfs Outflow=320.26 cfs 27.672 of
Reach 107Ra: Ditch 107_Shallow Avg. Flow Depth=1.66' Max Vet=6.27 fps Inflow=371.86 cfs 28.812 of
n=0.025 L=870.0' S=0.0069 '/' Capacity=1,739.55 cfs Outflow=364.26 cfs 28.812 of

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 51
Reach 107Rb: Ditch 107_Steep Avg. Flow Depth=0.90' Max Vet=12.37 fps Inflow=364.26 cfs
28.812 of
n=0.025 L=570.0' S=0.0561 T Capacity=4,963.15 cfs Outflow=363.52 cfs
28.812 of
Reach 109R: Ditch 105 Avg. Flow Depth=0.79' Max Vet=9.85 fps Inflow=161.21 cfs
8.942 of
n=0.025 L=950.0' S=0.0442 '/' Capacity=2,959.13 cfs Outflow=158.57 cfs
8.942 of
Reach 206Ra: Channel 201 Avg. Flow Depth=1.95' Max Vet=5.87 fps Inflow=427.16 cfs
39.810 of
n=0.025 L=1,800.0' S=0.0050'/' Capacity=8,724.30 cfs Outflow=409.13 cfs
39.810 of
Reach 206Rb: Channel 201 Avg. Flow Depth=2.83' Max Vet=7.22 fps Inflow=841.89 cfs
87.073 of
n=0.025 L=2,430.0' S=0.0049 '/' Capacity=8,670.28 cfs Outflow=785.90 cfs
87.073 of
Reach 207R: Channel 202 Avg. Flow Depth=1.15' Max Vet=4.30 fps Inflow=175.42 cfs
14.193 of
n=0.025 L=1,300.0' S=0.0050 '/' Capacity=8,724.30 cfs Outflow=166.07 cfs
14.193 of
Reach 208R: Channel 202 Avg. Flow Depth=1.32' Max Vet=4.66 fps Inflow=214.10 cfs
19.225 of
n=0.025 L=1,100.0' S=0.0050'/' Capacity=8,724.30 cfs Outflow=208.34 cfs
19.225 of
Pond 10OP: SE Detention Option 1 Peak EIev=580.09' Storage=1,840,776 cf Inflow=940.07 cfs
80.093 of
Primary=73.00 cfs 80.939 of Secondary=0.00 cfs 0.000 of Outflow=73.00 cfs
80.939 of
Pond 103P: SW Detention Option 2 Peak EIev=566.00' Storage=35,000 cf Inflow=0.00 cfs
0.000 of
Primary=4.65 cfs 0.530 of Secondary=0.00 cfs 0.000 of Outflow=4.65 cfs
0.530 of
Pond 104P: NE Detention Option 1 - Peak EIev=580.67' Storage=1,756,812 cf Inflow=991.55 cfs 106.298
of
Primary=247.01 cfs 107.055 of Secondary=0.00 cfs 0.000 of Outflow=247.01 cfs 107.055
of
Pond 107P: East SW Detention Option 3 Peak EIev=566.00' Storage=35,000 cf Inflow=0.00 cfs
0.000 of
Primary=3.12 cfs 0.529 of Secondary=0.00 cfs 0.000 of Outflow=3.12 cfs
0.529 of
Pond 108P: RAB Ex. Spillway (no storage) Peak EIev=0.00'
Primary=0.00 cfs 0.000 of Secondary=0.00 cfs 0.000 of Tertiary=0.00 cfs
0.000 of
Pond 200: RAB Outlet Pond (no storage) Peak EIev=0.00'
Primary=0.00 cfs 0.000 of Secondary=0.00 cfs 0.000 of Tertiary=0.00 cfs
0.000 of
Link 102L: Lake Wylie/Catawba River
Link 104L: Lake Wylie/Catawba River
Inflow=73.00 cfs 81.998 of
Primary=73.00 cfs 81.998 of
Inflow=247.01 cfs 107.055 of
Primary=247.01 cfs 107.055 of
Total Runoff Area = 513.877 ac Runoff Volume = 186.391 of Average Runoff Depth = 4.35"
100.00% Pervious = 513.877 ac 0.00% Impervious = 0.000 ac

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type 1124-hr 100-year Rainfall= 7.39 "
Printed 1/15/2020
HvdroCAD®10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 102S: DA 102
Runoff = 335.39 cfs @ 12.02 hrs, Volume= 18.331 af, Depth= 4.16"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN DescriDtion
807,646 60
107,375 61 >75% Grass cover, Good, HSG B
1,386,358 80
2,301,379 72 Weighted Average
2,301,379 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
6.6 100
0.0500
0.25
Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
3.6 750
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fDs
10.2 850 Total
Subcatchment 102S: DA 102
Hydrograph
3n�
340
335.39
cfs
320
300
L 1
L
280
260
II 1
1
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L
240
220
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120
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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 53
Summary for Subcatchment 103S: DA 103
Eastern Face of Mound
Runoff = 225.62 cfs @ 12.03 hrs, Volume= 13.307 af, Depth= 5.06"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN Description
1,375,819 80 Final Cover
1,375,819 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
6.6 100
0.0500
0.25
Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
5.2 1,100
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
11.8 1,200 Total
Subcatchment 103S: DA 103
Hydrograph
250-
11
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240
220
225.62 cfs
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210
200
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0
0 2 4 6 8 10 12 14 16 18 20 2224 2628 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 54
Summary for Subcatchment 104S: Area Draining to 104
Runoff = 187.79 cfs @ 12.06 hrs, Volume= 11.842 af, Depth= 5.06"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN Description
1,224,363 80 Final Cover
1,224,363 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
9.6 100
0.0500
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.41"
4.3 900
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
13.9 1,000 Total
Subcatchment 104S: Area Draining to 104
Hydrograph
210
1 1
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200 190
187.79 cfs
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170
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150
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10
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 55
Summary for Subcatchment 105Sa: Area draining to 105
Runoff = 86.86 cfs @ 12.28 hrs, Volume= 8.840 af, Depth= 5.06"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN Description
914,000 80 Final Cover
914,000 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
9.6
100
0.0500
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.41"
4.5
950
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
18.5
1,100
0.0200
0.99
Shallow Concentrated Flow, shallow 2
Short Grass Pasture Kv= 7.0 fps
32.6 2,150 Total
Subcatchment 105Sa: Area draining to 105
Hydrograph
HIH I�
I�
1
HI
HI
L
H
95
90
85
86.86 cfs
1HIHIHIHI
HI
I� �
HI HI H H�p 111: � �
5 7
70
H I
1 H
1 H H 1
H
H
H-Maid# Atela#M010"f
60
H
+
+ H
FF "pff Q
U 50
IH
H
H I H I
H I
HI
HI HI nll'l
0 45
W _Len =� 1 50
LL 40
35
1 H
1 H 1 H 1
H
HI
HI HI H IH Ilc�ii mi�
30
1+
1 H 1+ 1+-
1
HI
HI H H H H IHt-W6-M
25
20
HHIHH
H
H H H H H H HHI
15
10
/
IH 1
I H I H 1
H
H
HI H H IH IH I H 1 H 1 H
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
■ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 56
Summary for Subcatchment 106S: DA 106
Area that drains using HydroCAD catchmentarea +38.75 acres to the southwest of the basin by the pond
Runoff = 330.94 cfs @ 12.18 hrs, Volume= 27.672 af, Depth= 4.05"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN Description
1,208,372 60 Woods
962,761 75 Residential
305,686 74 >75% Grass cover, Good, HSG C
1,091,208 80 Final Cover
3,568,027 71 Weighted Average
3,568,027 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
9.5
100
0.0200
0.18
Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
14.1
1,235
0.0436
1.46
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.6
600
0.0100
17.56
1,264.11 Trap/Vee/Rect Channel Flow,
Bot.W=30.00' D=2.00' Z= 3.0 '/' Top.W=42.00'
n= 0.012
24.2 1,935 Total

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 57
Subcatchment 106S: DA 106
Hydrograph
360
—4 I rt
i—+
I� I
4-1
H
H
1-4 1 --t-I rt I� � 1 4— � I H
❑Runoff
340
330.94
cfs
1
� 1
4I
�I
�I
I�
1-4 14 14 1 T � jiI-i4_f�
320
300
4
4-1
-k I
t-I
280
260
22o
L
LI
LI
El
I�ow In TI'1Lil
o ,8o
I— i-
—
—
TI
-I
-I
❑
unoff � l
I— RFI L
o
E 160
140
Ft
TITI
F
FI
F-I
1t F 17 1 U 44.1-ini
120
fi t-r
I-r
l
�I
r-I
I-1
1- rt I rt I T 1 1 GG"71
100
80
1 t I
t I
t 1
t-I
�-I
I�
I� 1-� 1 t I t I t I fit t-1
60
40/
I�
1+IiIt-IHH1-tI-�1-�I+Ii-I
I�-1
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type 1124-hr 100-year Rainfall= 7.39 "
Printed 1/15/2020
HvdroCAD®10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC
Summary for Subcatchment 107Sa: Northwest AAB
Runoff = 240.21 cfs @ 12.06 hrs, Volume= 15.004 af, Depth= 4.05"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN Description
456,118 80 Final Cover
704,538 61 >75% Grass cover, Good, HSG B
773,974 75 Residential
1,934,630 71 Weighted Average
1,934,630 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
9.6 100
0.0500
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.41"
4.5 950
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fDs
14.1 1,050 Total
Subcatchment 107Sa: Northwest AAB
Hydrograph
I —T I I I I I—r I -r-
240.21 cfs
I� - III I I L
I� 1 -ICI+I i-
-" 140 +
3
LL 120 + t
100 fi
80 IIIIII
60 1--F
40
20
F1 F-I I-T I-T 17 1 TTYp�+l _ 1.
LI LI 1-60Ly ill4R"f�li 4.130't
-�-1 �-I IA4np# r4► a�r+,9�41,Q3Q 0
IRulnp�o�[u�r�'1'��
I- (Runoff Depth --*.Or
t--I r-I I-1 1-t I rt rt 11Td 4.IFinlrii
IIIIIII I I I I ICM=71
P 1-1 1-4 1- -+ I � I 4--1 �-I
T T FI
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 59
Summary for Subcatchment 107Sb: NW of North face of AAB
Runoff = 78.21 cfs @ 12.06 hrs, Volume= 4.968 af, Depth= 5.06"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN Description
513,700 80 Final Cover
513,700 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.6 100 0.0500 0.17 Sheet Flow,
Grass: Dense n= 0.240 P2= 3.41"
4.5 950 0.2500 3.50 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
14.1 1,050 Total
Subcatchment 107Sb: NW of North face of AAB
Hydrograph
85 — I .� I I L 14 1 Runoff
1 78.21 cfs I I I J- I I I �I I —I 1� �I
75 11 4-h1`
75
70 L I LI LlL 1 bb-aiRnIl.�i�'�
60 7 L TI L Riilf#'ela'Ifi3�7fOp#
55 t It t I t 1 t 1 _fit 1�yp°I�1 Y�I���f�
3 45 I� �I �I �I%njoaffl ePTI 0 40 — — W L " 35 1� I i I - �I �I 1 I �I �I L-I u 1� e��# i ��' SA
30Ci�. 1�
25 11111 L I L I L I LL LL It I—L I—L MI6-"
20 15 IT �I �I rI 1—I �I I� 1-1Irt 17
10 / t I t 1 -1 I tI �� i--I 11 II� I t I t
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 60
Summary for Subcatchment 108S: Area draining to 102
Runoff = 161.21 cfs @ 12.01 hrs, Volume= 8.942 af, Depth= 5.06"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN Description
924,571 80 Final Cover
924,571 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
6.6 100
0.0500
0.25
Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
3.1 650
0.2500
3.50
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fDs
9.7 750 Total, Increased to minimum Tc = 10.0 min
Subcatchment 108S: Area draining to 102
Hydrograph
180
I1
-F
I T I
T I
P
F
11 —[F T I
❑Runoff
170
160
161-21
cfs
rt
fi
fi
�I
l
rt rt ��I -
150
-
-
-
-
-
-
-� ar— Ql
— —
130
4
-RJMn'II' /I"'��IIe6#97=`I"1' ;U0
110
� 1
4-I
�I
fff
-T °r Y° i Ig'T9 �
0 190
I
� 1
4I
�I
�I
I —I I�� I° I�� II-5 0 1
LL 80
70
! 1
11
El
El
low Lin h=�5Q
El It I - _L60
50
-
-
-
-I
-II-
I- - -T—
30
20
/
fi
t
t-1
I t t tI t-I
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 61
Summary for Subcatchment 201S: DA 201
Area that drains using HydroCAD catchmentarea +38.75 acres to the southwest of the basin by the pond
Runoff = 427.16 cfs @ 12.22 hrs, Volume= 39.810 af, Depth= 4.16"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN Description
899,000 60 Woods
1,250,000 75 Residential
2,239,000 74 >75% Grass cover, Good, HSG C
610,000 80 Final Cover
4,998,000 72 Weighted Average
4,998,000 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
20.8
100
0.0200
0.08
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.41"
3.5
150
0.0200
0.71
Shallow Concentrated Flow, shallow
Woodland Kv= 5.0 fps
4.4
500
0.0740
1.90
Shallow Concentrated Flow, shallow
Short Grass Pasture Kv= 7.0 fps
28.7 750 Total

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 62
Subcatchment 201 S: DA 201
Hydrograph
460
--4I
--+
14
4
fi
�I
1- � 14 1 � 14 �
❑Runoff
4
440
20
427.16
cfs
fi
�I
HH
I
F ps + � _ 1
400
380
1
T- I
� I
�I
�1
I�
IVOLy-ye"Aifi]&4136t
360
340
1-t
+ I
+ I
t-I
�-1
-R4np"r"4,q"1,0Q 0
�ur_w
H 280
260
-
c�„
Run L�cpt��'F 1 F�
220
I�
I-
-
-
-
-I
-I
—
I— -Fi �I ,h�ii4
_2
200
v. 180
r71
CI
17t 1- 1 1 7"X
1
140 0
1-�
1+
1�
I
H
H
I�
H 14 4 1+ 1 4- ��T?
120
10
80
1
11
L
LI
L
I� 1- 1 111 -LI -LI L
40
I�
I-
�I
�I
�I
I�
1� 14 4 1 � 1 4-1 �--I �I
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 63
Summary for Subcatchment 202S: DA 202
Area that drains using HydroCAD catchmentarea +38.75 acres to the southwest of the basin by the pond
Runoff = 175.42 cfs @ 12.16 hrs, Volume= 14.193 af, Depth= 4.05"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN DescriDtion
620,000
60 Woods, Fair, HSG B
570,000
74 >75% Grass cover, Good, HSG C
640,000
80 Final Cover
1,830,000
71 Weighted Average
1,830,000
100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
20.8 100
0.0200
0.08
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.41"
2.0 300
0.2500
2.50
Shallow Concentrated Flow, shallow
Woodland Kv= 5.0 fps
22.8 400 Total
Subcatchment 202S: DA 202
Hydrograph
�
4-
-i
-4+ �
190
180
170
175.42
cfs
T-
4
-k
�I
I
1-4 I I417 p�+I LL��FF ff
1 60
150
140
1-
1
+ 1
4-I
H
�-1
-Rulnp# r"F,1�$�Q,Q0Q 0
130
120
_
1-
1-
+ I
+ 1
4
�-_4-0
u�l l �uIT'
w 110
�noff �Orl
0 100
� 90
�
�
�
�
�
�
�
N
� 1+wpfh
L1Gn�ih �6
LL 80
4+
I+
H
H
N
—fi
I- 4 4 1 fd=:i�.-infnl
70
60
—
-
50
40
+ I
+ I
HHH1—fI
+ -IH
30
20
10
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 64
Summary for Subcatchment 203S: DA 203
Runoff = 80.07 cfs @ 12.06 hrs, Volume= 5.032 af, Depth= 4.38"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN Description
600,000 74 >75% Grass cover, Good, HSG C
600,000 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
9.5
100
0.0200
0.18
Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
2.5
150
0.0200
0.99
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
0.8
200
0.3333
4.04
Shallow Concentrated Flow, shallow
Short Grass Pasture Kv= 7.0 fps
1.4
250
0.1800
2.97
Shallow Concentrated Flow, shallow
Short Grass Pasture Kv= 7.0 fDs
14.2 700 Total
Subcatchment 203S: DA 203
Hydrograph
LI
LLI
80
1 8 111 cfs
17
L L 17
17-I
r1 1i ri rt II �
It t
L
L L I
fi
fit-
1
770
65
H I-
I L
I L L I-
-I
�-R th6 f AdtelaOMAO"f
60
55
4
14
1 L I
-
-I
��"Clff��I
45
I�
�I
�I �I n1°1 nnj
low �wt 00
LL 40
35
L
1 L I L I
LI
LI
�1
LI LI L IL 130
25
ITITITITI
TI
FI FI ❑ I—T 17 I720 ��
15
rt
IL
L
fit
fit
�I �I I� Irt Irt IL L
10/
It
I LILIL
I
tI
t
I—t It ILILI
14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70
Time (hours)
■ Runoff

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 65
Summary for Subcatchment 204S: RAB Landfill Area
Runoff = 338.55 cfs @ 12.02 hrs, Volume= 18.451 af, Depth= 4.38"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Type II 24-hr 100-year Rainfall=7.39"
Area (sf) CN Description
2,200,000 74 Pasture/grassland/range, Good, HSG C
2,200,000 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.5 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.41"
9.5 100 Total, Increased to minimum Tc = 10.0 min
Subcatchment 204S: RAB Landfill Area
Hydrograph
ILi
�I
LI
LI
LI
LI L
360 340
,338.55
cfs
L III
L
El
El
❑
I1 1 11 I
�
�f
320
300
Ft
-L
—
—
LL
❑
�� —I ��I3-
�O� T+
280
260
I-7 1
-T
ITI
L I
L
T—I
F—I
I140W ► F AOI,90Q 10
22o
I�
rt
rt
LI
�I
�I
Iulp1°r 1'71 1
� no��-F1�wlp�h � 38 �
o ,so
—F 111 Le:�
LL 160
rt
t I
t I
t l
�I
�I
I-1
I� I rt I M6pte�46 010�
140
120
I—t
I t I
L I
L I
�I
�—I
I� 1- t ITrq -R•q-I
100
80
h
t I
t I
t I
�I
H
I�
1� 1 1 t I t F r
60
40
I�
+ I
L I
0 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68
Time (hours)
❑ Runoff

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type 1124-hr 100-year Rainfall=7.39"
Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC
Summary for Reach 102R: Ditch 102
[62] Hint: Exceeded Reach 106R OUTLET depth by 0.98' @ 12.05 hrs
[62] Hint: Exceeded Reach 109R OUTLET depth by 1.79' @ 12.19 hrs
Inflow Area = 155.968 ac, 0.00% Impervious, Inflow Depth = 4.23" for 100-year event
Inflow = 660.68 cfs @ 12.04 hrs, Volume= 54.945 of
Outflow = 587.28 cfs @ 12.11 hrs, Volume= 54.945 af, Atten= 11 %, Lag= 3.9 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 6.79 fps, Min. Travel Time= 5.9 min
Avg. Velocity = 1.36 fps, Avg. Travel Time= 29.3 min
Peak Storage= 207,687 cf @ 12.11 hrs
Average Depth at Peak Storage= 2.34'
Bank -Full Depth= 4.50' Flow Area= 195.8 sf, Capacity= 1,916.64 cfs
30.00' x 4.50' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 57.00'
Length= 2,400.0' Slope= 0.0054 T
Inlet Invert= 608.00', Outlet Invert= 595.00'

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 67
Reach 102R: Ditch 102
Hydrograph
700
I I TI
660.68 cfs T
I I
N
1 1 1
1 T T 1
1 1 T1 I i I I I
JII--�� 11
■ Inflow
■outflow
650
soo
587.28 cfs
I
A%/ j 1 046"I�#���1
550
T
T
T
IT T I
T 1 T X-VO�Q � V
450
T TI
H
I4
1 T T 1
TI H 1- I4 1 T� Q•��51
S-0 �5 /
G
300
1 TI
H
I-t
I T T I
tda�a�ii ill 19tl 6�4 �is�
250
1 LI T
T
T
1T TI
TI T T IT ITI TI T
200
150
T I TI
T
I T
IT T I
-1-1 1-1 IT I T IT -1-1 TI
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 68
Summary for Reach 104: Ditch 104
Inflow Area = 28.108 ac, 0.00% Impervious, Inflow Depth = 5.06" for 100-year event
Inflow = 187.79 cfs @ 12.06 hrs, Volume= 11.842 of
Outflow = 166.22 cfs @ 12.11 hrs, Volume= 11.842 af, Atten= 11 %, Lag= 3.3 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 4.14 fps, Min. Travel Time= 6.2 min
Avg. Velocity = 0.87 fps, Avg. Travel Time= 29.6 min
Peak Storage= 62,215 cf @ 12.11 hrs
Average Depth at Peak Storage= 0.94'
Bank -Full Depth= 4.00' Flow Area= 208.0 sf, Capacity= 2,039.57 cfs
40.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 64.00'
Length= 1,550.0' Slope= 0.0058 T
Inlet Invert= 588.00', Outlet Invert= 579.00'
Reach 104: Ditch 104
Hydrograph
200
1 187.79 c�
H
HI
I4
1 _� I H 11�fl" I�r��a 81. id8 (
190
170
166.22 cfs
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160
150
fi l
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140
130
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110
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4050
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id
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
■ Inflow
■ outflow

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 69
Summary for Reach 106R: Ditch 106
Inflow Area = 81.911 ac, 0.00% Impervious, Inflow Depth = 4.05" for 100-year event
Inflow = 330.94 cfs @ 12.18 hrs, Volume= 27.672 of
Outflow = 320.26 cfs @ 12.22 hrs, Volume= 27.672 af, Atten= 3%, Lag= 2.4 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 5.39 fps, Min. Travel Time= 3.7 min
Avg. Velocity = 1.28 fps, Avg. Travel Time= 15.8 min
Peak Storage= 71,931 cf @ 12.22 hrs
Average Depth at Peak Storage= 1.69'
Bank -Full Depth= 4.50' Flow Area= 195.8 sf, Capacity= 1,833.82 cfs
30.00' x 4.50' deep channel, n= 0.025
Side Slope Z-value= 3.0 7' Top Width= 57.00'
Length= 1,210.0' Slope= 0.0050 T
Inlet Invert= 614.00', Outlet Invert= 608.00'
$
\
ppr,
Reach 106R: Ditch 106
Hydrograph
360
330.94 cfs
320.26
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In Inflow
❑ outflow
340
cfs
320 00
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14 Ig�ni��t��l9'
280
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H
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260
240
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220
3200
H 4-1
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180
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14
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1160 40
100
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80
,
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I-4
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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type 1124-hr 100-year Rainfall= 7.39 "
Printed 1/15/2020
HvdroCAD®10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC
Summary for Reach 107Ra: Ditch 107_Shallow
Inflow Area = 77.188 ac, 0.00% Impervious, Inflow Depth = 4.48" for 100-year event
Inflow = 371.86 cfs @ 12.07 hrs, Volume= 28.812 of
Outflow = 364.26 cfs @ 12.10 hrs, Volume= 28.812 af, Atten= 2%, Lag= 1.4 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 6.27 fps, Min. Travel Time= 2.3 min
Avg. Velocity = 1.44 fps, Avg. Travel Time= 10.1 min
Peak Storage= 50,498 cf @ 12.10 hrs
Average Depth at Peak Storage= 1.66'
Bank -Full Depth= 4.00' Flow Area= 168.0 sf, Capacity= 1,739.55 cfs
30.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 7' Top Width= 54.00'
Length= 870.0' Slope= 0.0069 7'
Inlet Invert= 628.00', Outlet Invert= 622.00'
Reach 107Ra: Ditch 107 Shallow
Hydrograph
411
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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Inflow
❑ Outflow

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type 1124-hr 100-year Rainfall=7.39"
Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 71
Summary for Reach 107Rb: Ditch 107_Steep
[61] Hint: Exceeded Reach 107Ra outlet invert by 0.90' @ 12.10 hrs
Inflow Area = 77.188 ac, 0.00% Impervious, Inflow Depth = 4.48" for 100-year event
Inflow = 364.26 cfs @ 12.10 hrs, Volume= 28.812 of
Outflow = 363.52 cfs @ 12.10 hrs, Volume= 28.812 af, Atten= 0%, Lag= 0.5 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 12.37 fps, Min. Travel Time= 0.8 min
Avg. Velocity = 2.93 fps, Avg. Travel Time= 3.2 min
Peak Storage= 16,745 cf @ 12.10 hrs
Average Depth at Peak Storage= 0.90'
Bank -Full Depth= 4.00' Flow Area= 168.0 sf, Capacity= 4,963.15 cfs
30.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 54.00'
Length= 570.0' Slope= 0.0561 T
Inlet Invert= 622.00', Outlet Invert= 590.00'
E9

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 72
Reach 107Rb: Ditch 107_Steep
Hydrograph
400
lrAI
t t I I t l t 1 t—I
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■ Outflow
380
363.52
cfsI 11 rt IA
1�fl" �r"1 iT ii"cl
360
340
1:1 ZI ❑ ❑ II IIpg4-gE$j"b b]gbo
320
300
1
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280
260
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240
3 200
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1180
60
140
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120
100
80
1 4-1 u I::1 I: z I :F-I F 1: I:T I T- I :F-I :�:I 1-4
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 73
Summary for Reach 109R: Ditch 105
Inflow Area = 21.225 ac, 0.00% Impervious, Inflow Depth = 5.06" for 100-year event
Inflow = 161.21 cfs @ 12.01 hrs, Volume= 8.942 of
Outflow = 158.57 cfs @ 12.03 hrs, Volume= 8.942 af, Atten= 2%, Lag= 1.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 9.85 fps, Min. Travel Time= 1.6 min
Avg. Velocity = 2.27 fps, Avg. Travel Time= 7.0 min
Peak Storage= 15,288 cf @ 12.03 hrs
Average Depth at Peak Storage= 0.79'
Bank -Full Depth= 4.00' Flow Area= 120.0 sf, Capacity= 2,959.13 cfs
18.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 7' Top Width= 42.00'
Length= 950.0' Slope= 0.0442 T
Inlet Invert= 650.00', Outlet Invert= 608.00'
Reach 109R: Ditch 105
Hydrograph
IH
IH iM
180
170
161.21 cfs
158.57 cfs
71
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150
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140
130
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110
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0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
❑ Inflow
❑ outflow

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type 1124-hr 100-year Rainfall= 7.39 "
Printed 1/15/2020
HvdroCAD®10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Paae 74
Summary for Reach 206Ra: Channel 201
Inflow Area = 114.738 ac, 0.00% Impervious, Inflow Depth = 4.16" for 100-year event
Inflow = 427.16 cfs @ 12.22 hrs, Volume= 39.810 of
Outflow = 409.13 cfs @ 12.29 hrs, Volume= 39.81Oaf, Atten= 4%, Lag= 4.1 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 5.87 fps, Min. Travel Time= 5.1 min
Avg. Velocity = 1.58 fps, Avg. Travel Time= 18.9 min
Peak Storage= 125,528 cf @ 12.29 hrs
Average Depth at Peak Storage= 1.95'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,724.30 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 7' Top Width= 90.00'
Length= 1,800.0' Slope= 0.0050 '/'
Inlet Invert= 598.00', Outlet Invert= 589.00'
Reach 206Ra: Channel 201
Hydrograph
460
440420
400
427.16
409.13
c�:�j
cfs
1
HI
H
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380
360
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340
320
300
14
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280
240
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200
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140
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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
■ Inflow
■ outflow

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type 1124-hr 100-year Rainfall=7.39"
Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 75
Summary for Reach 206Rb: Channel 201
[62] Hint: Exceeded Reach 107Rb OUTLET depth by 1.06' @ 12.27 hrs
[62] Hint: Exceeded Reach 206Ra OUTLET depth by 1.32' @ 12.07 hrs
Inflow Area = 242.432 ac, 0.00% Impervious, Inflow Depth = 4.31" for 100-year event
Inflow = 841.89 cfs @ 12.08 hrs, Volume= 87.073 of
Outflow = 785.90 cfs @ 12.17 hrs, Volume= 87.073 af, Atten= 7%, Lag= 5.3 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 7.22 fps, Min. Travel Time= 5.6 min
Avg. Velocity = 1.82 fps, Avg. Travel Time= 22.2 min
Peak Storage= 264,461 cf @ 12.17 hrs
Average Depth at Peak Storage= 2.83'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,670.28 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 90.00'
Length= 2,430.0' Slope= 0.0049 T
Inlet Invert= 589.00', Outlet Invert= 577.00'

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 76
Reach 206Rb: Channel 201
Hydrograph
■ Inflow
900
841.89 cfs
�
u
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� �
�
■outflow
850
soo
785.90 cfs
� �l
750
700
I
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650
600
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0 450
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350
350
_
300
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250
200
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150
ift
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 77
Summary for Reach 207R: Channel 202
Inflow Area = 42.011 ac, 0.00% Impervious, Inflow Depth = 4.05" for 100-year event
Inflow = 175.42 cfs @ 12.16 hrs, Volume= 14.193 of
Outflow = 166.07 cfs @ 12.21 hrs, Volume= 14.193 af, Atten= 5%, Lag= 3.3 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 4.30 fps, Min. Travel Time= 5.0 min
Avg. Velocity = 1.21 fps, Avg. Travel Time= 17.9 min
Peak Storage= 50,166 cf @ 12.21 hrs
Average Depth at Peak Storage= 1.15'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,724.30 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 7' Top Width= 90.00'
Length= 1,300.0' Slope= 0.0050 T
Inlet Invert= 590.00', Outlet Invert= 583.50'
Reach 207R: Channel 202
Hydrograph
1-4
10
180
175.42
cfs
H
H
I4
1+ 1 I- I
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160
166.07
fs
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150
140
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30
E
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
■ Inflow
■ outflow

Closure Plan HydroCAD model 1.13.20
Prepared by AECOM
Allen CbE Jan. 2020
Type 1124-hr 100-year Rainfall=7.39"
Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC
Summary for Reach 208R: Channel 202
[62] Hint: Exceeded Reach 207R OUTLET depth by 0.20' @ 12.08 hrs
Inflow Area = 55.785 ac, 0.00% Impervious, Inflow Depth = 4.14" for 100-year event
Inflow = 214.10 cfs @ 12.16 hrs, Volume= 19.225 of
Outflow = 208.34 cfs @ 12.21 hrs, Volume= 19.225 af, Atten= 3%, Lag= 2.8 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 4.66 fps, Min. Travel Time= 3.9 min
Avg. Velocity = 1.30 fps, Avg. Travel Time= 14.1 min
Peak Storage= 49,185 cf @ 12.21 hrs
Average Depth at Peak Storage= 1.32'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,724.30 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 7' Top Width= 90.00'
Length= 1,100.0' Slope= 0.0050 T
Inlet Invert= 583.50', Outlet Invert= 578.00'
E9

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 79
Reach 208R: Channel 202
Hydrograph
H
H
I
H
1--� 1 4— 1 -t--- I H I-4 1 4 1-t- 1 4-1 H
Inflow
230
220
214.10 cfs
208.34 cfs
H
H
H
It t 1�#�" Atr"15T546"H C
■ outflow
200
I- 1
H
I-4
I-4
1 4 I,q�,lg j ��
190
110
70
1- I
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10
150
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1 1 1 -1 H IH 14 1 0�I.4251
Z 140
3120
I- IHHI�11111�IHIH
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100
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70
60
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it t 1 t 1 H IH I-t It t 1 t—I
fl
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 80
Summary for Pond 10OP: SE Detention Option 1
Keeping pond below 25 feet in height and 50 acre-feet of storage to avoid dam classification
[62] Hint: Exceeded Reach 104 OUTLET depth by 0.92' @ 13.75 hrs
Inflow Area = 215.660 ac, 0.00% Impervious, Inflow Depth = 4.46" for 100-year event
Inflow = 940.07 cfs @ 12.08 hrs, Volume= 80.093 of
Outflow = 73.00 cfs @ 13.69 hrs, Volume= 80.939 af, Atten= 92%, Lag= 96.1 min
Primary = 73.00 cfs @ 13.69 hrs, Volume= 80.939 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 567.00' Surf.Area= 110,000 sf Storage= 36,667 cf
Peak Elev= 580.09' @ 13.69 hrs Surf.Area= 167,601 sf Storage= 1,840,776 cf (1,804,110 cf above start)
Plug -Flow detention time= 301.9 min calculated for 80.086 of (100% of inflow)
Center -of -Mass det. time= 290.5 min ( 1,128.1 - 837.6 )
Volume Invert Avail.Storage Storage Description
#1 566.00' 2,169,341 cf Custom Stage Data (Irregular)Listed below (Recalc)
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq-ft) (feet) (cubic -feet) (cubic -feet) (sq-ft)
566.00 0 0.0 0 0 0
567.00 110,000 1,340.0 36,667 36,667 142,891
582.00 177,000 1,630.0 2,132,675 2,169,341 214,960
Device Routing Invert Outlet Devices
#1 Primary 566.00' 20.0" Round Culvert X 2.00
L= 100.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 566.00' / 565.00' S= 0.0100 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 2.18 sf
#2 Secondary 581.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 5.00
Width (feet) 50.00 56.00 80.00
Primary OutFlow Max=73.00 cfs @ 13.69 hrs HW=580.09' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Barrel Controls 73.00 cfs @ 16.73 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=567.00' TW=565.70' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 81
Pond 10OP: SE Detention Option 1
Hydrograph
940.07 cfs
1,050
/
1,000
/
950
/
900
/
850
/
800
/
750
/
700
/
650
w 600
550
0 500
/
M 450
/
400
350
/
/
300
/
250
/
200
/
73.00 cfs
150
/
0.00
cfs
H
1- -I
1-+ 141" ai -
1
E
IH EI
IH I �I �0 F;-1pyz1j8%0qt
+
H
14 -I
14 1 -I H 1 +1 H 1+ 1 H I+
1 I
r]
1: ]--I
1:1 1 tl ::� I II t:� 1:1-- 1 n 1:r
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14 I -I
14 I -I H 1 +1 H 1+ 1 H I+
0 2 4 6 8 1012 141618 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
IMInflow
utflowimarycondary

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 82
Summary for Pond 103P: SW Detention Option 2
Keeping pond below 25 feet in height and 50 acre-feet of storage to avoid dam classification
Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Outflow = 4.65 cfs @ 0.00 hrs, Volume= 0.530 af, Atten= 0%, Lag= 0.0 min
Primary = 4.65 cfs @ 0.00 hrs, Volume= 0.530 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 566.00' Surf.Area= 105,000 sf Storage= 35,000 cf
Peak Elev= 566.00' @ 0.00 hrs Surf.Area= 105,000 sf Storage= 35,000 cf
Plug -Flow detention time= (not calculated: initial storage exceeds outflow)
Center -of -Mass det. time= (not calculated: no inflow)
Volume Invert Avail.Storage Storage Description
#1 565.00' 2,989,805 cf Custom Stage Data (Irregular)Listed below (Recalc)
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq-ft) (feet) (cubic -feet) (cubic -feet) (sq-ft)
565.00 0 0.0 0 0 0
566.00 105,000 1,310.0 35,000 35,000 136,564
581.00 170,000 1,600.0 2,043,019 2,078,019 207,177
586.00 195,000 1,690.0 911,786 2,989,805 232,135
Device Routing Invert Outlet Devices
#1 Primary 565.00' 20.0" Round Culvert X 2.00
L= 100.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 565.00' / 564.00' S= 0.0100 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 2.18 sf
#2 Secondary 585.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 5.00
Width (feet) 50.00 56.00 80.00
Primary OutFlow Max=4.65 cfs @ 0.00 hrs HW=566.00' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Outlet Controls 4.65 cfs @ 2.44 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=566.00' TW=565.70' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 83
Pond 103P: SW Detention Option 2
Hydrograph
Ill i� l--� l 4-1 � l 4- l -i l-4 l14 l �-4 l�
71Miiiiiiiiii1111i�t6�r666I:=i3151,666Id
+ I H Wi-I H I+ I -H I-iI+I H IC I+ -I H
0 2 4 6 8 1012 1416 18 20 22 24 2628 30 32 34 36 38 40 42 4446 48 50 52 54 56 58 60 6264 66 68 70 72
Time (hours)
■ Inflow
❑ Outflow
❑ Primary
■ Secondary

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 84
Summary for Pond 104P: NE Detention Option 1 - Pond 1
Keeping pond below 25 feet in height and 50 acre-feet of storage to avoid dam classification
[62] Hint: Exceeded Reach 206Rb OUTLET depth by 2.43' @ 13.05 hrs
[62] Hint: Exceeded Reach 208R OUTLET depth by 2.19' @ 12.97 hrs
Inflow Area = 298.217 ac, 0.00% Impervious, Inflow Depth = 4.28" for 100-year event
Inflow = 991.55 cfs @ 12.18 hrs, Volume= 106.298 of
Outflow = 247.01 cfs @ 12.93 hrs, Volume= 107.055 af, Atten= 75%, Lag= 44.7 min
Primary = 247.01 cfs @ 12.93 hrs, Volume= 107.055 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 567.00' Surf.Area= 98,000 sf Storage= 32,667 cf
Peak Elev= 580.67' @ 12.93 hrs Surf.Area= 156,563 sf Storage= 1,756,812 cf (1,724,145 cf above start)
Plug -Flow detention time= (not calculated: outflow precedes inflow)
Center -of -Mass det. time= 73.2 min ( 924.1 - 850.9 )
Volume Invert Avail.Storage Storage Description
#1 566.00' 5,085,589 cf Custom Stage Data (Irregular)Listed below (Recalc)
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq-ft) (feet) (cubic -feet) (cubic -feet) (sq-ft)
566.00 0 0.0 0 0 0
567.00 98,000 1,310.0 32,667 32,667 136,564
582.00 163,000 1,600.0 1,936,941 1,969,608 207,177
601.00 165,000 1,610.0 3,115,981 5,085,589 237,779
Device Routing Invert Outlet Devices
#1 Primary 566.00' 36.0" Round Culvert X 2.00
L= 100.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 566.00' / 565.00' S= 0.0100 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 7.07 sf
#2 Secondary 581.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 5.00 20.00
Width (feet) 50.00 56.00 80.00 80.00
Primary OutFlow Max=247.01 cfs @ 12.93 hrs HW=580.67' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Inlet Controls 247.01 cfs @ 17.47 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=567.00' TW=565.70' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 85
1,100
1,050
1,000
950
900
850
800
750
700
650
u 600
3 550
c 500
LL 450
400
350
300
250
200
150
0.00 cfs
Pond 104P: NE Detention Option 1 - Pond 1
Hydrograph
�9�91.55
11 L
1a � 12 1L
f
cfs
H
I- HI
IH 141" b"a6 kild a is
Z� I
ITI
I: :F-I
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4 I
I+I
H
W -H
H 1-I H 1+I H I+1 H H
I1I
ICIH
111V
11ICI HI11 HHIH I-L
H
H
IH HI
IH HI H 1 + 1 H 1+ 1 H IH
247.01 cfLAWALs
- I
I� �I
I: TI H I T-I H 1� I 1 H
0 2 4 6 8 1012 141618 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)
IMInflow
utflowimarycondary

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 86
Summary for Pond 107P: East SW Detention Option 3
Keeping pond below 25 feet in height and 50 acre-feet of storage to avoid dam classification
Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Outflow = 3.12 cfs @ 0.00 hrs, Volume= 0.529 af, Atten= 0%, Lag= 0.0 min
Primary = 3.12 cfs @ 0.00 hrs, Volume= 0.529 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Starting Elev= 566.00' Surf.Area= 105,000 sf Storage= 35,000 cf
Peak Elev= 566.00' @ 0.00 hrs Surf.Area= 105,000 sf Storage= 35,000 cf
Plug -Flow detention time= (not calculated: initial storage exceeds outflow)
Center -of -Mass det. time= (not calculated: no inflow)
Volume Invert Avail.Storage Storage Description
#1 565.00' 2,078,019 cf Custom Stage Data (Irregular)Listed below (Recalc)
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq-ft) (feet) (cubic -feet) (cubic -feet) (sq-ft)
565.00 0 0.0 0 0 0
566.00 105,000 1,310.0 35,000 35,000 136,564
581.00 170,000 1,600.0 2,043,019 2,078,019 207,177
Device Routing Invert Outlet Devices
#1 Primary 565.00' 30.0" Round Culvert
L= 100.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 565.00' / 564.00' S= 0.0100 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 4.91 sf
#2 Secondary 580.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 5.00
Width (feet) 50.00 56.00 80.00
Primary OutFlow Max=3.12 cfs @ 0.00 hrs HW=566.00' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Outlet Controls 3.12 cfs @ 2.52 fps)
te2
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=566.00' TW=565.70' (Dynamic Tailwater)
=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Page 87
3.12 cfs
3
w 2
u
3
0
LL
1-
0.0
0.00 cfs
Pond 107P: East SW Detention Option 3
Hydrograph
i i l i l i i l i l l i l i i i i l i i l i l i i l i l I
I I I I I I I I I I I I I I I I I I�tb�rag�e��315I,bbb ICf
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
IIIIIIIIIIIIIIIIIIIIIIIIIIII
0 2 4 6 8 1012 1416 18 20 22 24 2628 30 32 34 36 38 40 42 4446 48 50 52 54 56 58 60 6264 66 68 70 72
Time (hours)
■ Inflow
❑ Outflow
❑ Primary
■ Secondary

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 88
Summary for Pond 108P: RAB Ex. Spillway (no storage)
[43] Hint: Has no inflow (Outflow=Zero)
Device
Routing
Invert
Outlet Devices
#1
Primary
611.00'
42.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 611.00' / 606.00' S= 0.1000 '/' Cc= 0.900
n= 0.012, Flow Area= 9.62 sf
#2
Secondary
618.90'
Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 5.00
Width (feet) 20.00 60.00
#3
Tertiary
624.25'
Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 5.00
Width (feet) 200.00 200.00
Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' TW=565.70' (Dynamic Tailwater)
L1=Culvert ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' TW=565.70' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)
Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' (Free Discharge)
L3=Custom Weir/Orifice ( Controls 0.00 cfs)
Pond 108P: RAB Ex. Spillway (no storage)
Hydrograph
❑ Primary
❑ Secondary
■ Tertiary
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 89
Summary for Pond 200: RAB Outlet Pond (no storage)
[43] Hint: Has no inflow (Outflow=Zero)
Device Routing Invert Outlet Devices
#1 Primary
570.20' 36.0" Round RCP Culvert
L= 114.3' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 570.20' / 566.40' S= 0.0332 '/' Cc= 0.900
n= 0.012 Concrete pipe, finished, Flow Area= 7.07 sf
#2 Device 1
606.12' 42.0" Round 42" Culvert Steep
L= 56.3' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 606.12' / 570.20' S= 0.6380 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 9.62 sf
#3 Device 2
609.10' 42.0" Round 42" Culvert Shallow
L= 27.3' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 609.10' / 606.12' S= 0.1092 '/' Cc= 0.900
n= 0.013, Flow Area= 9.62 sf
#4 Device 3
611.09' 54.0" Round 54" Culvert
L= 20.5' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 611.09' / 609.10' S= 0.0971 T Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 15.90 sf
#5 Secondary
618.90' Emergency Spillway, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 5.25
Width (feet) 20.00 28.00 36.00 44.00 52.00 60.00 60.00
#6 Tertiary
624.25' 260.0' long x 40.0' 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) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' TW=565.70' (Dynamic Tailwater)
L1=RCP Culvert ( Controls 0.00 cfs)
L2=42" Culvert Steep ( Controls 0.00 cfs)
Lt42" Culvert Shallow ( Controls 0.00 cfs)
4=54" Culvert ( Controls 0.00 cfs)
te5
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' TW=565.70' (Dynamic Tailwater)
=Emergency Spillway ( Controls 0.00 cfs)
Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' TW=565.70' (Dynamic Tailwater)
L6=Broad-Crested Rectangular Weir( Controls 0.00 cfs)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 11 24-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HydroCAD®10.00-25 s/n 09114 ©2019 HydroCAD Software Solutions LLC Page 90
Pond 200: RAB Outlet Pond (no storage)
Hydrograph
N Primary
1 i Secondary
■ Tertiary
I�eail� E���v-b.bb
3
0
LL
0.00 Cfs
0
0 2 4 6 8 10 1214 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall= 7.39 "
Prepared by AECOM Printed 1/15/2020
HvdroCADO 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 91
Summary for Link 102L: Lake Wylie/Catawba River
Inflow Area = 215.660 ac, 0.00% Impervious, Inflow Depth = 4.56" for 100-year event
Inflow = 73.00 cfs @ 13.69 hrs, Volume= 81.998 of
Primary = 73.00 cfs @ 13.69 hrs, Volume= 81.998 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Fixed water surface Elevation= 565.70'
Link 102L: Lake Wylie/Catawba River
Hydrograph
—t I fi l fi l fi l
l I t--1 I--� I—t I fi l fi l fi
■ Inflow
■Primary
73.00 cfs
__4
1
14 I I I 1-1��I C
92
T LI
LJ
-L
— — — —
I -L I -L I L I LI It I-L I -L11
FI7I7ITIFIFII-1I-1
iT
� .
21
'
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

Allen CbE Jan. 2020
Closure Plan HydroCAD model 1.13.20 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 1/15/2020
HydroCAD® 10.00-25 s/n 09114 © 2019 HydroCAD Software Solutions LLC Paae 92
Summary for Link 104L: Lake Wylie/Catawba River
Inflow Area = 298.217 ac, 0.00% Impervious, Inflow Depth = 4.31" for 100-year event
Inflow = 247.01 cfs @ 12.93 hrs, Volume= 107.055 of
Primary = 247.01 cfs @ 12.93 hrs, Volume= 107.055 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Fixed water surface Elevation= 565.70'
Link 104L: Lake Wylie/Catawba River
Hydrograph
260
247.01 cfs
H H
IH
I H H
I�i-ilow
Area=298.217
ac
❑ Inflow
❑ Primary
240
IIII
Illllllllllllllllll�lllillli
220
200
IH
HI H
IH
1 H H 1
HI
H
IH
14 H 1
HI
HI
180
IIII
IIIIIIIIII1-IF
1-1 111111111
160
140
—
H
HI H
IH
1 H H 1
H
H
IH
14 1 H 1
HI
—
H I-
3
LL120
IIIIIIIIIIIIIIIIIIIIIIIIIII
100
80
H
1 H
IHIHIHIHI
H
IH141
1HI
H
60
-1
IT TIT
n
17
17 1 TI
T1
11 1
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
Time (hours)

APPENDIX C2
Borrow Soil Quantities

AECOM
Job
Description
Duke Energy — Allen Closure
Soil Borrow Quantities
Closure by Excavation
Project No.
60572629
Sheet
1 of 2
Computed by
AMC
Date
1/14/20
Checked by
ANR
Date
1/17/20
The purpose of this memorandum is to summarize the results of the borrow soil demand quantity
calculations for closure -by -excavation of the Allen Steam Station Ash Basins. As the design is
further developed, these quantities will be refined. The quantities included herein are to be
considered a rough -order -of magnitude.
Soil borrow demand quantities that were calculated at this stage of the design include the
following:
- Fill: Backfill in closure -by -excavation areas following removal of CCR materials to promote
surface water drainage and to stabilize these areas.
- Cut: Breaching the RAB North Dike and AAB East Dike.
- Cut: Excavation of perimeter stormwater channels and detention ponds.
Required borrow soil volumes were calculated using AutoCAD. The net cut balance of borrow soil
is represented as a soil surplus. This analysis shows that sufficient quantity of soil borrow is
anticipated to be generated by the project, however additional material, if necessary, is assumed
to be available in other locations on the Duke Allen property (confirmation pending).
The estimated borrow soil demand quantities are summarized in Table 1 below, along with
additional assumptions and notes.

AECOM
Job Duke Energy — Allen Closure Project No. 60572629 Sheet 2 of 2
Description Soil Borrow Quantities Computed by AMC Date 1/14/20
Closure by Excavation Checked by ANR Date 1/17/20
Table 1— Summary of Borrow Soil Cut/Fill Quantities
Retired Ash Basin (RAB)
Description
Quantity
Unit
Notes
Cut
808,000
CY
- 38K CY cut for breaching RAB North Dike
- 620K CY cut for excavation of RAB channels
- 150K CY cut for Detention Pond
Fill
394,000
CY
-
- 394K CY fill for backfill of CbE areas
RAB soil surplus
414,000
CY
- Cut minus fill
Active Ash Basin (AAB)
Description
Quantity
Unit
Notes
Cut
583,000
CY
- 81K CY cut for breaching AAB East Dike
- 460K CY cut for excavation of perim. Channels
- 42K CY cut for excavation of Detention Pond
Fill
230,000
CY
- 230K CY fill for backfill of CbE areas
AAB soil surplus
353,000
CY
- Cut minus fill
Total Soil Surplus
(RAB + AAB)
767,000
CY
Assumptions:
1. No adjustments were used for material swelling, shrinkage, settlement, and waste.
2. Material quantities generated by removal of the RAB Landfill are excluded.
3. Material quantities for construction of the proposed AAB and Initial Landfills are excluded.
4. Material quantities for backfill of CbE areas based on one foot of cut and soil replacement in areas outside
of proposed landfill boundaries, and within the CCR Unit Boundary, in addition to fill required for
construction of perimeter channels.