_Allen CBE - Appendix C_20200107

APPENDIX C
ENGINEERING EVALUATIONS AND
ANALYSES

APPENDIX Cl
STORMWATER

I_a141•7►i
Job Duke Energy — Allen Closure by
Excavation
Description Stormwater Calculations
Project No. 60603204 Sheet 1 of 8
Computed by NSF Date 9/25/19
Checked by DMB Date 9/26/19
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 overthe proposed
final grades of the Allen Steam Station Active Ash Basin (AAB) and Retired Ash Basin (RAB) under
post -closure conditions. This analysis also evaluates the capacity of the existing RAB spillways for
managing runoff generated by the Probable Maximum Precipitation (PMP) storm event. The
conveyance channels, culverts, detention ponds, and existing and proposed spillways are shown
in Attachment CI -A.
I. 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).

AECOM
Job Duke Energy —Allen Closure by
Excavation
Description Stormwater Calculations
Project No. 60603204
Computed by NSF
Checked by DMB
Sheet 2 of 8
Date 9/25/19
Date 9/26/19
The Allen Closure Project (closure project) will consist of removing the free water from the AAB,
excavating the existing CCR materials to support the construction of a landfill in the AAB (AAB
landfill), and constructing several channels and detention basins to convey drainage of stormwater
from the final closure grades to one of three 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, another detention basin will be constructed upstream of the existing RAB spillway.
The northern portion of the AAB landfill and a portion of the RAB will be graded to drain to this new
detention basin which will then discharge directly to the existing RAB spillway. Lastly, the RAB dam
will be breached in the northeast corner, and a third detention basin will be installed upstream of
the breach. The majority of the RAB will be graded to drain to this detention basin which will then
discharge directly to Lake Wiley/the Catawba River.
The final designs will include stormwater conveyance channels that collect runoff from the drainage
basin and safely convey stormwater flows to the three detention basins. The existing AAB spillway
will be abandoned, while the RAB primary and emergency spillways will remain. 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

AECOM
Job Duke Energy —Allen Closure by
Excavation
Description Stormwater Calculations
Project No. 60603204
Computed by NSF
Checked by DMB
Sheet 3 of 8
Date 9/25/19
Date 9/26/19
runoff throughout the AAB and RAB and to direct this runoff to one of the three detention basins
and their respective outfalls.
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. The attenuated peak stormwater
flows in the proposed conditions during the 100-year, 24-hour storm event will be less than the
existing peak stormwater flows from both the AAB and RAB.
Spillway Design Criteria
The existing RAB spillways will be evaluated for performance during the PMP storm event in
accordance with the "High" hazard classification of the RAB. The AAB will not be required to pass
the PMP storm event in the proposed conditions since its dam will be breached.
PROCEDURE
Probable Maximum Precipitation Determination
Applied Weather Associates (AWA) completed a site -specific Probable Maximum Precipitation
study (PMP Study) for the Allen AAB and RAB drainage basin (AWA, 2019). This study was
completed to estimate the rainfall during the PMP throughout the Allen AAB and RAB drainage
basin. The National Oceanic and Atmospheric Administration (NOAA) Hydrometeorological
Reports (HMRs) 51 and 52 are used for PMP approximation when a site -specific PMP study is not
done. In contrast, the AWA PMP study utilized more recent meteorological data and applies the
most current practices for defining the PMP compared with HMRs 51 and 52 (published in 1978
and 1987, respectively). The 6-hour local PMP was used for the AAB and RAB Closure Design,
which corresponds to a rainfall depth of approximately 25.7 inches.
AECOM was given three potential temporal distributions of the 6-hour, local PMP. These
distributions include the 10 percent, 90 percent, and synthetic distributions. The synthetic
distribution was selected as the PMP for this analysis as it resulted in the highest peak flows of
the three potential temporal distributions. The synthetic distribution also resulted higher peak
flows than the original PMP storm rainfall amount and temporal distribution used in previous

AECOM
Job Duke Energy —Allen Closure by
Excavation
Description Stormwater Calculations
IV.
Project No. 60603204
Computed by NSF
Checked by DMB
Sheet 4 of 8
Date 9/25/19
Date 9/26/19
analyses by AECOM, so it is the most conservative storm for this analysis. The distribution for
this storm event was provided by AWA and can be found in Attachment Cl-C.
The original PMP storm rainfall amount and temporal distribution used in previous analyses by
AECOM was obtained from the Allen Steam Station Hydrologic and Hydraulic Analysis, prepared
by URS as part of the Phase 2 Reconstitution of Ash Pond Designs (URS, 2014).
Channel and Detention Basin Design
A grading plan for the proposed conditions was prepared to establish slopes for the conveyance
channels and culverts. The minimum channel slopes were established during the design of the
grading plan to be 0.5%. The proposed grading for the proposed conditions was tied into the
existing terrain outside of the Ash Basin, and the conveyance channels were aligned to capture
offsite drainage. The proposed grading plan used forthe 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 three 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 C1-113.
Spillway Design
The HydroCAD model was used to calculate the extent of flooding upstream of the RAB spillways
during the PMP. During the PMP, the area upstream of the RAB spillways flood substantially. To
accurately represent this flooding, the downstream portion of the final grades was modeled as a
pond. Ponds in HydroCAD are used to determine the peak water surface elevation upstream of
culverts or other flow obstructions during large storm events. The model calculates the peak
water surface elevation in the pond, taking into account some storage and flow attenuation. This
model was used to verify that the existing RAB spillways meet the design criteria summarized
above in Section II, and that the RAB dam is not overtopped during the PMP.
NOTES/ASSUMPTIONS
The following is a list of key notes and assumptions made in completing this analysis.

I_a141•7►i
Job Duke Energy — Allen Closure by
Excavation
Description Stormwater Calculations
V.
Project No. 60603204 Sheet 5 of 8
Computed by NSF Date 9/25/19
Checked by DMB Date 9/26/19
• As described above, the rainfall amount and distribution for the PMP are based on the
values provided by AWA.
• 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
('hnnnalc
All channels in the proposed conditions have been preliminarily sized based on the grading 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. The attenuated peak stormwater flows in the
proposed conditions during the 100-year, 24-hour storm event will be less than the existing peak
stormwater flows from both the AAB and RAB. The existing peak stormwater flows are based on
the values provided in the Allen Steam Station Hydrologic and Hydraulic Analysis, prepared by
URS as part of the Phase 2 Reconstitution of Ash Pond Designs (URS, 2014). Each detention basin
is also below the minimum height and storage volume (25 feet and 50 acre-feet, respectively) for a

AECOM
Job Duke Energy —Allen Closure by
Excavation
Description Stormwater Calculations
Project No. 60603204
Computed by NSF
Checked by DMB
Sheet 6 of 8
Date 9/25/19
Date 9/26/19
structure to be classified as a dam as outlined in the North Carolina Dam Safety Law of 1967 (NC
General Statutes, 1967). See Tables 1 and 2 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.
Table 1— Detention Basin Summary
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
74
AAB dam
Culverts
breach
Upstream of
14
43
Single 18-inch
RAB Spillway
25
existing RAB
Culvert
spillway
Upstream of
16
48
Single 30-inch
Lake Wiley
88
RAB dam
Culvert
breach
Table 2 —100-year Discharge Summary
Discharge Basin
Existing 100-year
Discharge (cfs)
Proposed 100-year
Discharge (cfs)1
AAB
91
741
RAB
146
113 Z
Notes:
1. This discharge includes flows from the southern portion of the AAB landfill that are discharged through the detention pond upstream of the AAB dam
breach.
2. This discharge includes flows from the northern portion of the AAB landfill and the RAB that are discharges through the detention ponds upstream of
the existing RAB spillway and the RAB dam breach.

AECOM
Job
Description
VI.
Duke Energy —Allen Closure by
Excavation
Stormwater Calculations
Project No. 60603204
Computed by NSF
Checked by DMB
Sheet 7 of 8
Date 9/25/19
Date 9/26/19
Additional detailed results can be found in the HydroCAD model output report in Attachment Cl-
B.
Spillways
The results of the analysis indicate that the combination of the RAB primary and emergency
spillways is sufficient to pass the PMP storm event without overtopping the dam. In the proposed
condition, the RAB emergency spillway is expected to activate during a storm with a recurrence
interval of greater than 1000 years. The northern portion of the RAB dam and the AAB dam were
not evaluated for overtopping during the PMP storm event due to the dam being breached in
these locations. See Table 3 below for a summary of the peak discharges and elevations of the
existing RAB spillways during the PMP storm event.
Table 3 — RAB Spillway Summary during PMP
RAB Spillway
Peak PMP
Peak PMP
Peak WSE (ft)
Top of Dam
Freeboard (ft)
Inflow (cfs)
Discharge
EI. (ft)
(cfs)
Primary
776
157
622.26
624.25
1.99
(Culverts)
Emergency
776
619
622.26
624.25
1.99
(Weir/Channel)
The preliminary analysis of the PMP storm event was limited to assessing the hydraulic capacity
of the conveyances during peak design flows. Future analyses during detailed design will include
further evaluation of channel stability and lining design, which could involve consideration of
different flow regimes. These future analyses could result in adjustments/refinements to spillway
and channel configurations.
Additional detailed results can be found in the HydroCAD model output report in Attachment Cl-
B.
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 existing RAB spillways are also sufficient to safely control and

I_a141•7►i
Description
VI 1.
1VAIIA
Duke Energy — Allen Closure by project No. 60603204 Sheet 8 of 8
Excavation
Stormwater Calculations Computed by NSF Date 9/25/19
Checked by DMB Date 9/26/19
convey the flow from the PMP storm event. The attenuated peak stormwater flows from the
detention basins during the 100-year, 24-hour storm event will be less than the existing peak
stormwater flows from both the AAB and RAB. 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.
ATTACHMENTS
Attachment Cl-A: Figures
Attachment Cl-B: HydroCAD Report
Attachment Cl-C: AWA PMP Study
f I011014 7011\rdTIN
AECOM, 2018. Phase 2 Reconstitution of Ash Pond Designs Report (Rev. 4), Allen Steam Station.
April 26, 2018.
Application of Probable Maximum Precipitation Estimates — United States East of the 105th
Meridian. Hydrometeorological Report No. 52. NOAA. August 1982.
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:Hhdsc.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

ALN C901.021.015 wv. A
LEGEND
\\\
ALLEN STEAM STATION \\
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ri
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\ lI --_ _ /'\----- � .' �\\�X\` \ \\
\ 1 I \ \\ / \\\\ 1 \\@ f I RAB DIKE BREACH �11 \
ICI 600� - _ .\\\ \�____� ��c' �61� , (SEE NOTE 6)r� - ^h,\ PROPOSED CULVERT UNDER
_ �I �� _ _ _� / I RAILROAD (SIZE TBD)
Lo
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— — —
POTENTIAL vY,., � � ww � - � LAKE WYLIE/
SWITCHYARD till
OO'/ lCATAWBA RIVER
PROVIDED BYCDUKOEN I 1 ,- Q--'' 1 \_., - _ --- /' IIIII I�i ol!� NORMAL W.S.E. 565.7 FT.
/O w `
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/ •
` / FUTURE STORMWATER
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-// I j I -=--------------
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_ TL 5N5 500kV r-\\\-------------- - - - -__- -I I I I
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1 ' I '� ,' BY DUKE \ / / ,w , _'`-- �'� III I i I i( - �' << I I i i l I i�'ilili ELEVATION: 571.3 FT.
) �� ,_�\ `` ,�/ii�I IIIII RETIRED ASH BASIN LANDFILL (TO REMAIN)
c - ��----- TL 2A10 (230kV) 1 _� I,,I !!1! ASH LANDFILL PERMIT NO. 36-12 I I I 111 III
/ - 625 _---- - I �'I''III 111111I
I 1 ' - - (TO BE RELOCATED _ /; ^�`��\� TL 1A482 'lirli I /
600 - BY DUKE -:' ', - - 1 ) l ii ii ' I i i �cooi' I
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1 _ 6`SO\\ ` �_ —' '-------- i I I I I I' 11 RAB LANDFILL SLOPE I III 1 1 II IIIII 1111 i'
\ w r I I II I I I III GRADING NOT SHOWN
STABILIZATION FEATURE (IIII / ` II 1 III IIII III I ( )
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-O ` /.-' ; '' 1 IIIII —_ _ --_ _---_ _`>�•___---_---_'JIII �' Ilil it
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\ / /------------ �- a� r
o \ I \ \\\ STORMWATER DITCH ^1 / `\\O\\�� ------
0
STORMWATER RUNOFF FROM APPROX 20 ACRES OF o '�--`\ 11\\ i _ _ _ �_ - NORTH DIKE -= �_--- - _ ____= � � =\�I I1111 IIII
CO / NORTHWEST AAB AREA TO BE REDIRECTED TO RAB. \ _ __ !! = =-- _� —-Iliil\II 1I'I Ir�
/ 1w r�/�--�II�I�i IIII I I I
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0
1 \ \ I N i i _ _/i ® liiiilii IIIII IIII SWO15
AAB NORTH / Ii11i1i' IIIII I I
IN, STORMWATER DITCH ®€ ®€ il11 111 fill IIII COAL YARD SUMP
/` ,11��1111 11i l I1 I DISCHARGE
IF ) /1 ® I 11l 1111 IIII I (ABANDONED)
TL 1A482 (100kV) I!lilll! i;ill ,I
(TO BE RELOCATED I N i N i I ool
)
i BY DUKE Co.-i°I I,C° 11-1 II
6�6 - _ , g5� r �liiiilii IIIIII IIIIII II AAB EAST
cr _ I I I STORMWATER DITCH
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// --- --- \111jfill I 11 1 11111I I
III I 11111 IIIIII
I j
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° I 1111 I'1 fill 111111
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\I,Ililii ii111 ii1 Ii CATAWBA RIVER
! (100kV) ] 1 \ nI lu1 111'lll NORMAL W.S.E.
PROPOSED AAB 1 '11111i1n!1! III II
11
CHEMICAL \.�� LANDFILL 0l lii1 w � ii1111 I 565.7 FT.
TL 5N5 I \ \ I i o i i o
\ \ BUILDING III Y
/ \ i \ '\ .-\ \\ (500kV) I o 1111 o p l i p
I h Lo I I I 1 �% \ 1 / \ �S :_�- �\ xk �--- III U) if �I I
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/ TL 2A10 - I IIIII w 0 1111 1
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\ \\ \ 1'111111 li 111
\ IIII I11� I IIII 11 \ MANAGEMENT AREA
1 I \ 1�1 \ --- 11111111 11 II'i \\ (GRADING NOT SHOWN)
1 I r
11 Jill \ \\
JURISDICTIONAL STREAM
AAB WEST III 111, 1 IIIII
STORMWATER DITCH __ `1i�11j11 '11� 1i Ili1i1
j11
/
w \�1 �\ I it = IIII
6 J
1\ O / 00it
/ 111 II II
I
_ _
\ \ 1 III 1111 ll I 1111
//
IIII I I
I
LAKE WYLIE
100-YEAR FLOOD
ELEVATION: 571.3 FT.
v) ` _ � _- CHEMICAL � � �iillll I Ill�l \ AAB DIKE BREACH
BUILDING \I\.1111�/�I 1 III III ��\\ (SEE NOTE 6)
REMOVED
( ) \ PERMITTED SPILLWAY
AAB SOUTH
STORMWATER DITCH - 6 `\ \ /� �1/' �____ -- _ �•�/�'/ o/ \ \\ \
0 EXISTING \ _ I �\
NPDES
_ WTS PAD ' \\ OUTFACE
I ,• / / 1 �" Off\
co
-
`\11 If
i i" \\ i I\ \\ \ \\ \\ •/ // 1_ / / /� - // AAB SOUTH
'STORMWATER DITCH
JURISDICTIONAL STREAM
625
- - - - 625 - - - -
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
LL LIMITS OF EXISTING RAB LANDFILL LINER
LIMITS OF ASH
• • � • • � LIMITS OF WATER
100—YR 100 YR FLOOD LINE
HATCH LEGEND
WETLAND (SEE NOTE 4)
POTENTIAL HABITAT - SCHWEINITZ'S
SUNFLOWER (SEE NOTE 3)
PROPOSED AAB LANDFILL LOCATION
FUTURE STORMWATER MANAGEMENT AREA
POTENTIAL SWITCHYARD LOCATION
PROPOSED RAB LANDFILL SLOPE STABILIZATION FEATURE
EXISTING RAB LANDFILL
NinTPc
1.
LIMITS OF IMPOUNDED ASH ARE APPROXIMATE.
2.
REFER TO SHEET ALN_C901.021.002 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
AREAS.
4.
POTENTIAL JURISDICTIONAL WATERS (STREAMS/WETLANDS) WERE IDENTIFIED BY
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.
5.
WORK WITHIN THE 100-YEAR FLOODPLAIN ALONG THE SHORELINE OF THE CATAWBA
RIVER MAY REQUIRE PERMITTING.
N
6.
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 MANAGEMENT.
7.
THE PROPOSED GRADES SHOWN FOR THE STORMWATER DITCHES ARE CONCEPTUAL
AND WILL BE FURTHER DEFINED ON THE BASIS OF FUTURE DETAILED DESIGN AND
SUBSURFACE INVESTIGATION.
0 300 600 900
NOT FOR CONSTRUCTION
GRAPHIC SCALE (IN FEET)
TITLE
P"=com
SEAL
N.C. ENGINEERING LICENSE NO.
F-0342
FINAL GRADING PLAN
ALLEN STEAM STATION
CLOSURE PLAN FOR CLOSURE BY REMOVAL
GASTON COUNTY, NORTH CAROLINA
FOR
ISSUED FOR REVIEW
SCALE: AS SHOWN DES: ANR
ow DUKE DWG TYPE :. DWG DFTR : AMC
JOB NO:60603204 CHKD: JDM
�' ENEIRGY® DATE: 9-3-19 ENGR: JDM
FILENAME: ALN_C901 .021 .015 FINAL GRADING PLAN.D GPD: JDM
DWG SIZE DRAWING NO. REVISION
ANSID 22.0"x34.0" ALN —C901.021.015 A
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SEAL
of 1(4
EXISTING WASTEWATER /
TREATMENT AREA ��� �/' ' / ;/;//' / , // '' ► \ I ,
------ /'� `\ . CCR UNIT BOUNDARY ' i / / t i i / \\217 `_-__; ; \ \ I / I I 1
/I.X11,111%
N.C. ENGINEERING LICENSE NO.
F-0342
ALN_
ALN_C901.021.036 qgy, A
LEGEND
625
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
LL
LIMITS OF EXISTING RAB LANDFILL LINER
LIMITS OF ASH
•
LIMITS OF WATER
100—YR
100 YR FLOOD LINE
SITING CRITERIA BUFFER LIMIT
—
PROPOSED DRAINAGE FLOW PATH
HATCH LEGEND
FUTURE STORMWATER MANAGEMENT AREA
0 150 300 450
GRAPHIC SCALE (IN FEET)
0[6il4,
1. GROUNDWATER LEVELS SHOWN ON CROSS SECTIONS WERE
OBTAINED FROM THE GROUNDWATER FLOW AND TRANSPORT
MODELING REPORT FOR ALLEN STEAM STATION, BELMONT,
NC, BY SYNTERRA CORP., DATED NOVEMBER 2018, WHICH
CORRESPONDS TO THE "ALLEN EXCAVATION H&H, 2—FT
CONTOUR, LAYER 12" GROUNDWATER CONTOUR MAP
PROVIDED TO AECOM BY SYNTERRA CORP. IN ACCORDANCE
WITH THE FEDERAL CCR RULE, A MINIMUM 5—FOOT BUFFER
IS REQUIRED BETWEEN THE UPPERMOST AQUIFER AND
BASE OF THE LANDFILL LINER SYSTEM. THE PROPOSED
BOTTOM LINER SYSTEM IS ADDUMED TO INCLUDE A
2—FOOT THICK COMPACTED SOIL LAYER BELOW THE
GEOSYNTHETIC LINING AND LEACHATE COLLECTION SYSTEM.
TITLE
NOT FOR CONSTRUCTION
ON -SITE LANDFILL SCHEMATIC PLAN
ALLEN STEAM STATION
CLOSURE PLAN FOR CLOSURE BY REMOVAL
GASTON COUNTY, NORTH CAROLINA
FOR
ISSUED FOR REVIEW
SCALE: N.T.S. DES: ANR
fft� DUKE DWG TYPE :. DWG DFTR : AMC
,blnw
B N HKD: JO 0 2 4 C JDM
ENERGYC DATE: 903039 ENGR: JDM
q1 E036-037 ON -SITE LANDFILL SCHEMATIC.DWG APPD: JDM
DWG SIZE DRAWING NO. REVISION
ANSI D ALN C901.021.036
22.0"x34.0" — Q
1
�ID

ATTACHMENT C1-6
HydroCAD Modeling Output

CM1an e1201
01S cneppel 201
DA zat
zoas
DA 03
208 —
CM1annel202
10156
NW p1 wAe lapea
1oaS
Area.�iaip glo loz
lid
1065 Dnch 10
DA t06 108
DncM1 1.
1025
�DA 102
102 -
106 DIICM1 102
NorIM1 SW Detention
Option 3
Subcat Reach Pon Link
IS
2045 �j
OA t 04
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Rlver
200
t05
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105 RAB E6, Sp,ll y(nD
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1D /
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1045
Area Drffip1a0 m 104
1o3S
DA 103
102
100
La WyllelCalavAa
SW OelenllDn Optlpn t Rlver
SW Deten110n Optlan 2
1�
Eazi6W DNe wa
Oplip 3

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 2
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 Description
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 fps
10.2 850 Total
Subcatchment 102S: DA 102
Hydrograph
-- -I-I-I -I -I I I I rt rt t t r r r 1 -I -1-1 rt rt T T fi t 1
260
1 1 1 1 1 1 1 F F 1 1 1 1 1 1 1 1 1 T 1
250
240
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1 233.sfi ds 4 4 T T t- I I I I 1 1 1 A -4-4 T T� ��
230
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160
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y 150
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LL 110
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40
- I- I- -I -I + t f- - I- I- I- I -1 -1 -1 --1-+ -+ + + t t
30
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC
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
(min) (feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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
180
IIIIIII l i l l i i i l l IiiiIIiiII I I I I I I I
170
ss.46 cfs
160
_ _ —1 —1 I I I I I I I I I — 1— 1— 1— I
i —i _I _1 —0 TI 24-hr
150
}_
11 1 1 1 1 1 1 1 1�511 � 0 iof� I' Wi
140
130
1 1 1 1 1 71"1 '
1 1-Runloff Arew=1 819 sf
120
�I375
11 1 1 1 ��Iu� �W�� r �1+�4.ffine:;�l•644
110
100
bb
- I- -I- -1 11 W4 �M�,T
1 �-1-f I I T T T 7 7 1 I I- I-RCCI 1
LL80
•L
---I- -I 7 7 Tr T---- IrloMtl 11E'i1gi1= 1,2lJVr
I I I��rtrtrtTrr r-I I I I I I I II
70
art+ • ,,,
I I I��1fi+tt1 �I I -1 -1 1=�1 O
50
- I- + + + T i - I- I- I- - -I -I + + t t
40
1 I-4-444+-4- I-1-1-1-1-1-1-1-4-1
30
TTt- 11 1 1 1 1 -1 --1 -4-4
20
TTt- 11 1 1 1 1 1 4 L-LL
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 4
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
J 1 1 L L L L L I I I I 1 1 1-1 L L L 1 1 L L L
150
— — — —
— — — — — — — — — — — — — — — — — — — — — — — — — — — — —
140
137.58
——
cfs
1-1 7-T 7 T T T T T T T I— 1— 1— 1-1 —1 —1 —1 -1 fide A -24-hr
130
— I— 1-1
-4 4 4 T T 4- �- �- I— 1— 1 C — 1 �•
120
4—
1 —r�
I •T 1
110
1-_ 1-_
Runoff IAr�ea',=, 11 .224.3Q68 Sf
100
_
-
Rum � �VtM�1,�F��•�f�+1�+1a�
rt T TT T L T T
w 90
I I-
1 1 A-4-4 4 1 T L L L` 1 Runoff Ddpth -3.v6r1-
80
I I I I I I I
0 70
LL—
—
r {
—I —I —I I I I I I 1 1 I I I I I— 1—IFIoNv1 Len t�= I,0O0r
60
—
11
— — — — — — — — — — — — — — — — — —
II
11 11 II II �� � �•�
I I �
� rt rt rt rt T T L L� I I I I I�
50
1 1-
1 1�-4-t 4 1 T L L L —1 --1 -t-4 4C-N=80-
40
30
20
—I -1 -t -t t t t t 1- t- t- I— I— I— 1-1-1-1 —1-1 � -t -t t t fi t t-
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

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC
Summary for Subcatchment 105Sa: Area draining to 105
Runoff = 103.10 cfs @ 12.06 hrs, Volume= 6.482 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
924,750 80 Final Cover
924,750 100.00% Pervious Area
Tc Length
(min) (feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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 105Sa: Area draining to 105
Hydrograph
115
110
105
100
103.10
- I- I.
cis
-I -L -L T T L- L- I- I- I- I- I - I -1 -1 --Type N 24-hr-
95
- 1=-I
1 1 T T T -I T T T-- �I - I
90
1-1
rtrtrr—C�r
1-1�rtrtfifirl-l- YP 1
85
80
--1-1
-I�_T_fTTTT-T_T_ RUrfbfMe�?9Z4_
75
-
I I-
1 1-1-1-1 1 1 1 L L L L IIRUnioff1Vollume__-& 82 -at
70
y 65
1 1 1-
T 1 L I
0UIInot �J
60
I I I I-
I I��� t t t t L�� I I I I •tp
o 50
= 1= 1_ I
-1 -1-1 7 7 7 T 7 7 7 7 1- 1_ 1_ IFWWA:bhPtNitQ5i r
45
_ _ I_
-I _I _ I- I- I- _ _I I
*1. 1_ Min
I_ I_ I_
40
-I _I _ _ _I _I _ITCi
35
1-
1 A-44411L 11 1 1 1 1 1- --4-4 I�
30
I I
I -i-i_+ t f t L 11 1 1 1 1 -1 __1 -f
2.5
1
1 1 1 1 r T 1 r r r 11 1 1 1 1 1-1 r r r 1 rt r r r
20
15
- -
- - - - - - - - - - - - - - - - - - - - - - - - - - -
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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 25-year Rainfall=5.87'
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Pane 6
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

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 7
Subcatchment 106S: DA 106
Hydrograph
I I I 1 1�-A + T i I I -4-4++ T
250
-----I-1-1-111rTTrrrrrrr-rrtTTr
240
220
_ _I _ _ II_ _I _I _I II
1 1 1�-4-4 4 4 T t- I __ I� Type A -24 -h r
210
zoo
1-2z.60t5230
- 1-1- 1111
--rt �1f I 7 •8
1
10
8
-1---1 -
1 1-1 -1 -1 - - L - - lnff lAr• w---3,56&,027 -sf-
160
— 1— 1—
—1
1 11
170
1 1 1 1 1 - - 1 1 1 �p I� �Iu �� 9•474 1a
150
140
— — — — — — — — — — — — — — — — — — —� .—,y — — — — — — �—y� — — -
1 1 1- 1 1-1-1-1111LLLL LI I RY11� D�pl#-LL79�L
130
1 1- 1 1�-A-4++TTt- I I I I 1 1��-4�4++T
c 120I-
1 T T T T T T T II�IONvI Len111�,9L
LL 110
100
-
_ 1_ 1_ 1 1 _1 _1 1 1 1 1 1 1 1 L L I_ 1_ I_ 1_ 1 _ 1 _1 _1 _1• ly
!�
90
_
I I- -1 1�-4-44+TTt- I I I I 1 I I-
80
- I- I- -1 -1 1 1 r T T r r r r I- I- I- I- I -1 -1 -1 -1 r r r MTV
70
60
_1_1 IIII
- — — — — — — — — — — — — — — — — — — — — — — — — — -
50
1�-4-444TTt- I I I I 1 1 -1 --1 -4-4++��
40
- I- 1- 1 1 -1 -t t t t t 1- t t I- I- I- I- I -1 -1 -1 -1 t t t t t t t t-
30
on—
111 1 1 1 1 F F F F 1 1 1 1 1 1 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

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC
Summary for Subcatchment 107Sa: Northwest AAB
Runoff = 156.32 cfs @ 12.06 hrs, Volume= 9.764 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
456,118 80 Final Cover
537,538 61 >75% Grass cover, Good, HSG B
773,974 75 Residential
1,767,630 72 Weighted Average
1,767,630 100.00% 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 fps
14.1 1,050 Total
Subcatchment 107Sa: Northwest AAB
Hydrograph
170
I I IIII
I I L L I I I I L ii I I I I I I I I
160
15s.32
cfs I
l t Type
11---
150
--
140
--11-I
zll� ,T
130
- -1-
I-11T-1-f7TTTTTT11-I-1�51T�/11* T �
-1 rt rt t t fir -Runoff IA_ rea 1-767. 6W -sfi
120
110
-I -4 -4 -4 4 4 T 4- 4- 1
H 100
I-
pp
-1-1-1 L L L T L L L I I I R"dff Ddpth--2.89-1--
90
_c 80
Flow Llength= I,O�O
a
70
# -�•
1—I'4'1
60
1 1 T"I'
50
--111
1 -I-1-T777TT7771 1-177TT777
40
__
-1 -1 1 1 rt t t r r f-f- I- I- I- I- I -1 -1 -1 -1-1 rt rt t t fi fi f-
30
- 1-1
1 -1 -f -i - + t f- - I- 1- 1-1 -1 -1 -1 -+ -+ + + t t
20
1 1'-
1-4-4 4 4 -k -k L I 11 1 1 1 1 1 -4 -4 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)
❑ Runoff

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC
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
min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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
+-------1-1-1-1-4-4+++4-��++++I--------I-I+
■Runoff
60
55
57.27 cfs
Tlyp�enll r
�I
-I -I -I -I -I + + +r iR1a�n� 111fin�.10
-yea
50
1 1 1 1 1 1 1 1 1 1 1 1 1 1
45
1 1 1 1 1 1 1 1 R-U h- 6 ff Are1aL511317OO tf
40
-1 -1 -1 -1 -1 -4 -4 -4 + + + 4- 4 4- 4-F -` 11- 1 1 -� -1 -1 -1 �
Runoff, Volume= 161O1 of
35
4- 4- L410I11-Oeo7h�116-_�
-II -II
_0 30
a
I I I I I F16W IL 1-051W
1 1 1 1 1 1 1 1 1 1 1 1 I I I
25
Tcr-14a-mia
20
i
15
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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 10
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
(min) (feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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 fps
9.7 750 Total, Increased to minimum Tc = 10.0 min
Subcatchment 108S: Area draining to 102
Hydrograph
� 1- I— 1— 1— 1-1 —1 —1 —1 � 4-
130
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
120
118.38cfs
4 4++t- 1 1 1 1 1 1 1 --Type 24-h i-
110
,N
1 1 1 1 1 1 1 -"elr �'rll�ll1
1 1 1 7
100
�/�,y A e
1 1 + + + 4- 4-/y1 Rdftff ea�92C57 tf
90
1
11
1 1
1 1 1 1 1 1 111 unto Vo11ume-1&481 of
80
70
111-
11 �ullnPf �Dleh�•;6.
LL 60
l l l l 1 1 l l Iz1b111/ 1Le�h-Jth1751O'
50
11-1 1 1 7 7 r r r r r l— I— I— I-1 —1 —1 —1 -1 r r 7 rt rt r r r
1 111 1—I-1-1-1-1_I—ITc-;:1Q.O min
40
-1-1-1
_
30
1 I I 1 1 1 1 I I I L L I I I 1 1 1 I I 1 1 1 1 1 1
20
-' -
10
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)
❑ Runoff

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 11
Summary for Subcatchment 201 S: DA 201
Area that drains using HydroCAD catchmentarea +38.75 acres to the southwest of the basin by the pond
Runoff = 269.52 cfs @ 12.22 hrs, Volume= 25.387 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
1,200,000 60 Woods
1,310,000 75 Residential
2,239,000 74 >75% Grass cover, Good, HSG C
4,749,000 71 Weighted Average
4,749,000 100.00% 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
Subcatchment 201 S: DA 201
Hydrograph
300
-t- L
280
I_ I_ 269.52cfs
1 1
260
-
-
I
-I -I I I I I I I I I I I I 1- 1-1 - -1 -1 -I Type TI -24-h r
240
-1-1
1-1 -1-T 7 7 T T T r 7 7 11
4Y1P=0
+++++I -I-
2201ItUn1off
1AreM 4j4%0OO tf
200
�n�
180
160
of �•� 0
L L 11- I- I- i_Ff I I� 't
-
-11 -1-1 1 -j -L
o 140
1 1 1 1 1 1 1 1 IFIow Lelncith=7501
LL
120
-
-1-1-177TTTTT 11 1 1 I mo 'T
100
�'L
1�-A-444TT� I I I I 1 1 1�-1A44'=7V
80
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
60
40t
I I I' -
1� rt rt rt rt T fi 1- �� I I I I I I I I�� rt rt rt rt fi 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

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 12
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 = 116.74 cfs @ 12.18 hrs, Volume= 9.930 af, Depth= 2.43"
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
1,020,000
60 Woods, Fair, HSG B
1,114,000
74 >75% Grass cover, Good, HSG C
2,134,000
67 Weighted Average
2,134,000
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"
2.4
100
0.0200
0.71
Shallow Concentrated Flow, shallow
Woodland Kv= 5.0 fps
0.8
100
0.1600
2.00
Shallow Concentrated Flow, shallow
Woodland Kv= 5.0 fps
24.0 300 Total
Subcatchment 202S: DA 202
Hydrograph
I;'u
125
120
1A-4-411T1L I I I I I I IA1II+TTT�115
— 1— 1-1
1116.74cfsTl
—1 -1 1 1 7 T T T r r r I— I— I— I-1-1-1-1-I ype l-24-hr
110
_ I_ I__I
_I 1 1 _ I_ p I II
CI 0fy 44
`/�1
100
I I
1 1 � -A -4 4 4 4- t- � I I I- -I I
95
- 1- 1-1-
�/�--�v #�
1 -1 -1 -T 7 7 T T T T 7 7 I noffI�re�2,13,tjM0aL
90
11
1 1 1 1 1 1 1 1 1 1 1 1 1 I I II II I I I I I I pI� I
IR
80
- I- I- -
1 -1 -4 -4 4 4 T + I- I
--= 1
=1 -1 -1 -T 7 7 T T L 7 7---- d ff D6�ft�A3'f-
70
c 60
II_
- I- I- 1
IIIICI111 1 1 1 1 111
1 -1 -4 -4 4 4 T + I- 1- 1- I- I - IFlow LeNth=300-
u 55
50
- -
-1I 1 1 11 1-1 '7
40
-A-411++LL I 1 1 1 1�1II @
��V�
35
- -
- 7 7 T T T 7 7 7 I I I I I I 11- 7 7 T T T T T
30
25
- -_J
J J J J L J J J I_ I- I- I-1 -1 -1 -I J J J J I I J J L
20
I I--1-11-++t-
F I I I I 1 1 1 1-111++tt�1.5
in
— —
1 1 7 T T 1 1 1 1 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

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 13
Summary for Subcatchment 203S: DA 203
Runoff = 165.26 cfs @ 12.06 hrs, Volume= 10.367 af, Depth= 3.37"
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
920,000 74 >75% Grass cover, Good, HSG C
690,000 80 Final Cover
1,610,000 77 Weighted Average
1,610,000 100.00% Pervious Area
Tc
(min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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 fps
14.2 700 Total
Subcatchment 203S: DA 203
Hydrograph
1 1 1 1 J-A -i L L L L L L L L i 1 1 i 1 J L L 1 1 L L L
180
I I I
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
170
160
165.26
cfs
A
1 T)* II 24-hr
150
—— 1— 1
}/1
—11 —1 1 1 1 1 1 �— 1�511 � �I��f 1�r'
140
130
1 1 1 1 1 71"7`•
1 1 1 1 1 1 RUnloff IAr ew=1,610,000 of
120
IIIIIIIII lj�ln4if 01 0I•�6� •1d
110
w
is 100
—
— —
— —1-11a111y �,T
-T-f T T T T T T T I1
0
— 1— 1-1
C
1 —1 -1 -1 1 T T T T T T T I— 1— 1— —1 — IFIow L �7OOr
80
11
0 7
I-60
(+�(�,
I I� rt rt rt rt fi fi fi� 1- I I I I I I I I� �� � �•�
50
�+ft��I�++LLB
40
I I-
1 1-A-4 4 1 L L t- I I I 11 1 1 1-4 4 + L L B
30
— I— I— I
1 —1 � -4 -4 4 4 4- � � I— 1— 1— 1-1 —1 —1 —1 � � -4 -4 4- 4-
20
— I— I— I
1 —1 -L -L — I— I— I-1 —1 —1 —1 -j -L -L 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)
❑ Runoff

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 14
Summary for Subcatchment 204S: DA 204
Runoff = 105.44 cfs @ 12.13 hrs, Volume= 7.928 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
1,131,000 80 Final Cover
1,131,000 100.00% Pervious Area
Tc
(min)
Length Slope
(feet) (ft/ft)
Velocity Capacity Description
(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,
Short Grass Pasture Kv= 7.0 fps
7.3
1,500 0.0067
3.40 108.91 Trap/Vee/Rect Channel Flow, Channel south of landfill
Bot.W=10.00' D=2.00' Z= 3.0 '/' Top.W=22.00'
n= 0.045
20.1
1,950 Total
Subcatchment 204S: DA 204
Hydrograph
115
1-1-A -4+++++++III 1-1++++++++ ❑Runoff
110
105.44 cts
fit + t 1 t t fi fi
105
--I
ICJ J 7 7 T T T 7 71 i--i ypeA-24-hr
100
90
- - - -
11 11 1
- - - - - -
11 11 J-1-1 1 1 1 L L L L 11 1 51171` ;�1,L
l
85
+ 1 1
1 1 � -A -4 + + + + + + + I nnn
1A�reW--ll .1 31+ON Sf-
80
75
- - 11-
- -
1
Dnoff
-I T r Isla r •�12
70
65
-
1 1 1-
bJ.,y
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1I��tlldff Deipth-I 166"
60
-
1 1_4_ 4+ T 1_ 1_ 1
_0 55
-I
}�T {T n�C�n�
+ t i I (Flow Length= t,95W-
LL 50
- - 1
-1 -1 -1 -f 7 T T T T 7 7 I- I- 1- 1-1 -1 -1 -I 7_ TT
45
�'
40
35
_ I_
1
J J J J J J L J J J I_ I_ I_ I_ _ _I _I J J J J AM80-
30
- I- 1
-1 -4 -4 -4 4 4- 4- I- 1- 1- 1-1-1-1 -1-4 -4 - T T + 4 �
25
- - 1
-1 -1 1 1 rt -r t fi 1- f- t- I- I- 1- 1-1-1-1 -1-1 -1 rt rt -r -r fi fi r
20
- --
-I-1JJ77TTT771 1-1777TT777
15
10
1 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 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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 15
Summary for Reach 102R: Ditch 102
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 '/'
Inlet Invert= 608.00', Outlet Invert= 595.00'
Reach 102R: Ditch 102
Hydrograph
I I I A 7� 4- L I 1-1-1 I T 4 4 T T t-�- I I I 1 I T 4 4 T T -
ITTTTTTI ITTTTTTTI ITTTTTTT
■Inflow
500
1111 asa.lscls 1 1 1 L L l 1 1 1 1 1 1 1 L L I I 1 T 1 1 1 L L L
❑Outflow
480
nflaw Area=I
460
1 1 I 7+++ I 1-1-1 I+ 7 7 -55.96&ac-
440
7TTTFI 1777T 5 7 T f-
420
400
i
,l,I
- - - - - - - - - - - - � . � � Y1� B — .8
I — 392.71 cfs L L I— I —1 -I L L
380
I-I-1-I I I I I I I t t t rMar-Vet_--5;941fps
360
AF
111111 1 T T 1 I 1 I 1 1 T T 1 I 1 1 1
340
320
i
i
- -- ---------------------
11 1 7 T T L I 1-1-1 IT 7 7 T T L I I 1 1 ITTn=01.
300
j�
I- 1-1 rt rt t 1- r- I- I-1-1 -I -1 rt rt rt t 1- r- I- I-1-1 -I rtwfin j.boo
F� {tJJ
;
260
c 240
i
i
-1-1 4 1- I-I-1-1-I 7 7 1- I-I-1-1S: &&.N54'/�
LL 220
7TTTTI IT77T TT IT7T�TT T
180
180
�
- I- 1 L L L L I- I- _I _I L 1 1 L L =1rj� 1V
160
1 1- 7+++I 11 1 I+77+++I 11 1 I+74+
140
I1 i T T T F F III I T 7 7 T T T F I T 7 7 T T F
120
100
�
1 1- 7 T T L I I I I IT 7 7 T T L I I I I IT 7 j T T!
80
-I-I t t t r--I-I-I t 7 7 t t t r I-I-1-1-I t 7 t t t I-
60
An
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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paoe 16
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 '/'
Inlet Invert= 588.00', Outlet Invert= 579.00'
Reach 104: Ditch 104
Hydrograph
I_ I_1_1 _1 J 1 1 L L L I_ 1_1_1 _1 __1-11 1 L L L I_ I_I_1 _1 L L L L L L
i t
III I I I I I I I I IIIII I I I I I I I IIIII I I I I I I I
150
140
,
1 137.58 cfs e�I I
1 1 1 1 1 1 1 1 1 1 Inflow Area=28AWa
130
I I rt rt +fir I I I rt rt rtt- fi r
vM llAAE�I I PP� ��rtII rt
120
118A5 cfs -4 4- t— k— 1 � 4
� �
110
/
I
I I I I I I I I I I I I I I I I I I I I W X1Iyo1 T 4.0 I_
I
100
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 h=�0.0251
90
80
/
1 I— - —I——-1 t+t-r I— I I I L=75-550.0'r
0 70
LL1 1-1-1 1 TT LLI I- I 1 L
60
I I I I I I I I I I I I I 0 I I
50R�T�Ittl7
40
7TTTL1 ITTTTTTTI 17TTT7-T_
30
4+++ I I 1 1 1--+T+++ I I 1 1 1 --+4+ --
1 1 L L L 1- 1-1-1 -1 L L L L L L L 1_ I I I T 1 _I 1
20
,
I I I I I I I I I I I I I I I I 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)
■ Inflow
❑ Outflow

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 17
Summary for Reach 105: Ditch 105
Inflow Area = 21.229 ac, 0.00% Impervious, Inflow Depth = 3.66" for 25-year event
Inflow = 103.10 cfs @ 12.06 hrs, Volume= 6.482 of
Outflow = 89.80 cfs @ 12.12 hrs, Volume= 6.482 af, Atten= 13%, Lag= 3.7 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 4.88 fps, Min. Travel Time= 6.8 min
Avg. Velocity = 1.17 fps, Avg. Travel Time= 28.4 min
Peak Storage= 36,610 cf @ 12.12 hrs
Average Depth at Peak Storage= 0.58'
Bank -Full Depth= 4.00' Flow Area= 168.0 sf, Capacity= 2,571.90 cfs
30.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 54.00'
Length= 1,990.0' Slope= 0.0151 '/'
Inlet Invert= 618.00', Outlet Invert= 588.00'
Reach 105: Ditch 105
Hydrograph
-1-1-1-1 -1 rt T T l- r- 1-1-1-1-1 7 7 rt T T l- r- 1-1-1-1-1 T-T rt T T r
115
110
i
i
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Tios.io5 T T L L 111 I T A I T T L L II1 I T A T T L L L
105
i
- I- -I 4 1- 1-1-1 -1 4 4 I-E1#low,Area=8 1+.2 (
100
95
i
II rtTTfirIITrtrt TT II Trt�rt� T r
- 89.8o cfs Avg* �Q th
90
85
/
/
r0.510 I
- - - - - - - - - - - - - - - - - - - - - - - - - - - -
_I_ I I I I 1 I_I_I_I_I_I I I I I 1 1 I_
80
i
I I 1 4 T T T L 1 1 1 1 -1 --1 4-4 T T T L X1 -00 L
75
i
1-1-1- -1TTt-r1 1-1-1 TT_t-iTTt-rI 11 IT�
Tn:O. 5-
70
60
i 1
T I I 1 1 1 1 1 1 1 1-ITT 1 1 1 1 1 1 1 1 1 L=1;99Q.O'L
c 55
1-1-1- -4 T T T L 1-1-1 1 T-t-4 T T T L I I I I 1 L
r
M 50
tt+t--I-I-I t+t
45
4035
1 TTTTLI TTT��+I'I
i
- 1 ITT�IttI T -
30
i
-i 1-1-1-1-1 -4 1-1-1-1-1 � -4 _� �_ I- .
25
i
-1-1- 4 T T T L 1 1-1-1 1T-t 4 T T T L 1 1-1-1 1T-t4++-{ L
20
II- T T T L I1111 T T TT T T T I1111 T T T T T T T
15
1 T T F_ 7
in
i 1
1 1 1 1 1 1 1 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)
■ Inflow
❑ Outflow

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen Cl 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC 118
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 1 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 '/' Top Width= 57.00'
Length= 1,210.0' Slope= 0.0050 '/'
Inlet Invert= 614.00', Outlet Invert= 608.00'
Reach 106R: Ditch 106
Hydrograph
-1-1-1-1­4 7++1- 1-I-1-1-I+77++1-�-I-I-I-1-I+74++�
1 1 1-1 7 T T T F 1 I T 7 7 T T T F 1 I I T 7 7 T T F F
2
240 40
�
-- 226.60 cfs 7 L L L L L 7 7 L L L L L 7 1 L L L
I
230
M A
t fi L Infl®wlA-rea=- 811.9t1+-ae-
Inflow
220
210
z17.35cis
}1�1
�� „
200
�
1 I 7T-LL 1 1 1 1 1177
180
-I-I -I tttt r- -I-I -I ttt
160
i
11 I 7T L 11 1 1 1�77T L I I 1 1 1�h=A.G25-
150
I I I -1 T T r r- I I I I -1 -1 rt rt T T r r- I I I I 1TrtrtTT1-r-
Lz1 Q.0'1
13o
;21
3 120
i
—1-1- 4 + + � 1— 1-1-1-1 + 7 7 + + 1---I—I—I -
0
z110
/w
7TTTF1 IT77TTT�1 1 1 1s1= VF
100
I -I -I_ 1 1 L L L 1-I-I-I-I -1 _ 1 ��(+ I• ��jjI _ w
80
1 1- ++ L 1-1-1-1-1---+ 7 1'�•"�"I I�7,
70
-I-I rTT_7F1 1777TTr-f-I 1T77TT_F
60
50
- - - - - - - - - - - - - - - - - - - - - - - - - - - - -
I I- 7 T L 1 1-1-1 1 7 7 T L I I I 1 1 7 J T !
40
-I-1 t t t- r 1-1-1-1-1 t 7 7 t t t- r I-I-1-1-1 t 7 fi t t I-
30
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 19
Summary for Reach 107R: Ditch 107
Inflow Area = 52.372 ac, 0.00% Impervious, Inflow Depth = 3.06" for 25-year event
Inflow = 213.56 cfs @ 12.06 hrs, Volume= 13.364 of
Outflow = 206.18 cfs @ 12.09 hrs, Volume= 13.364 af, Atten= 3%, Lag= 1.8 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 7.99 fps, Min. Travel Time= 2.9 min
Avg. Velocity = 1.86 fps, Avg. Travel Time= 12.6 min
Peak Storage= 36,135 cf @ 12.09 hrs
Average Depth at Peak Storage= 0.80'
Bank -Full Depth= 4.00' Flow Area= 168.0 sf, Capacity= 3,451.02 cfs
30.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 54.00'
Length= 1,400.0' Slope= 0.0271 '/'
Inlet Invert= 628.00', Outlet Invert= 590.00'
Reach 107R: Ditch 107
Hydrograph
I I IJ 1 L L L L 1 11 -1 -1 A_t 1 L L L L I I 1 -1 -1 A 1 L L L L
■Inflow
230
/
I I 2,3.ssc,s ++ L L 1 1 1 1 -t 4 + L L I II 11 1 �c -t 1 +_ L L
Outflow
220
�+
1- 1 rt rt _r r r 1- 1-1-1 -1 -i -t rt fl l 10w i71r�d =J2.372r- c-
210
206.,acrs
--I-I-I -I TI IIp }ICI �_
190
i
1 1- -4 _L _L L L I 11 1
180
1- 1- fi fi t I- I- -I -I fi fi t err 7.
170
�
xI
I I I I I I I I I I I I I I I I I I I I I �/ 1 T I
160
150
i
i
-
1 �y C
-I-1 1 L L L I- I -I -I -I J_L_L1 L L L 1-I-I-I-I L L
��{r��J
N 140
1-1-1- 4++LLI 1-1-1 1 -t 4 t- I- 11 1 1+-t1++LL
v 130
1 1 1- rt rt rt t-r I I I rt-t rt rt t- r 1 1 1 1 L-=-1 Ae®.e'L
_0 110
S==b�.�[LI�I����J111 �L
LL 100
i
- - 1 _L _L L L I- 1-1-1 -1 _j -A U _L _L L L I- I- -
90
- ttLL1 1 7 1 1 17
80
�
-� TTrLI I-I-I-I���
T
70
60
i
- - - - - - - - - -1 __1 -A - - - - - - - - - - - - - - -
- 1 1 L L L1 11 1 -A 1 L L L1 I I I IL A 1 L L L
50
-I-I + + 1- 1-1-1-1-1 -4 -4 + + 1- 1-1-1-1-1 -4 4 + 4-
40
I I- rt rt rt r r I 11 1 I rt rt rt rt r r I I I I I rtItfiLr
30
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 9.19.19
Prepared by AECOM
Allen Ci 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC 120
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, Attei 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 '/' Top Width= 42.00'
Length= 950.0' Slope= 0.0442 '/'
Inlet Invert= 650.00', Outlet Invert= 608.00'
Reach 109R: Ditch 105
Hydrograph
I I I A 4 T T T k- I 11 1 I T 4 4 T T T k- I 1I 1 I T 4 4 T T k-
� 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 I I I I I
130
120
/
1 1 118.38 cfs 1 1 1 1 1 1 1 IM 1 1 A I p 1 1 ♦ 1 n 1
I I 116.03cfs -f T T T I I I I T Inflow Area=2 It.g25-ae-
110
-I-I I I TI I Ipp I
���+�-001,pl �Iv�
I I I I I I I I I h
100Y
i
Xl=1 I7 S�
90
- - - -I-I--f
� I
n
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��W0251
80-
70
60
FL
/
I- 1 1 1 1 1 I I 1 �/ 1
/ �I
t
1 1 1�1=M1/a
50
I T T T T T T T T 00�kC'}I � I 5�
40
1-11- -4 t- I I 1 1 I T-t-4 I T • 11
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
30
I
1 1 1 1 1 1
20--I-I
�
-I + I- I-
�
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)
■ Inflow
❑ Outflow

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paoe 21
Summary for Reach 20613a: Channel 201
Inflow Area = 109.022 ac, 0.00% Impervious, Inflow Depth = 2.79" for 25-year event
Inflow = 269.52 cfs @ 12.22 hrs, Volume= 25.387 of
Outflow = 254.70 cfs @ 12.30 hrs, Volume= 25.387 af, Atten= 6%, Lag= 4.7 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 5.00 fps, Min. Travel Time= 6.0 min
Avg. Velocity = 1.43 fps, Avg. Travel Time= 21.0 min
Peak Storage= 91,768 cf @ 12.30 hrs
Average Depth at Peak Storage= 1.48'
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= 1,800.0' Slope= 0.0050 '/'
Inlet Invert= 597.00', Outlet Invert= 588.00'
Reach 20613a: Channel 201
Hydrograph
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300
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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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 22
Summary for Reach 20613b: Channel 201
Inflow Area = 161.394 ac, 0.00% Impervious, Inflow Depth = 2.88" for 25-year event
Inflow = 367.15 cfs @ 12.17 hrs, Volume= 38.752 of
Outflow = 360.44 cfs @ 12.23 hrs, Volume= 38.752 af, Atten= 2%, Lag= 3.4 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 5.68 fps, Min. Travel Time= 3.7 min
Avg. Velocity = 1.55 fps, Avg. Travel Time= 13.5 min
Peak Storage= 79,946 cf @ 12.23 hrs
Average Depth at Peak Storage= 1.79'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,861.70 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 90.00'
Length= 1,260.0' Slope= 0.0052 '/'
Inlet Invert= 588.00', Outlet Invert= 581.50'
$ t
Reach 20613b: Channel 201
Hydrograph
I_1_1_1
_1 J 1 1 1 L L I_ 1_1_1_11 1 1 1 1 L L I_ I_ I_ 1_11 H I L L
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11 1
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■Inflow
400
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❑ Outflow
380
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340
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80
/
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
60
/
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 23
Summary for Reach 207R: Channel 202
Inflow Area = 48.990 ac, 0.00% Impervious, Inflow Depth = 2.43" for 25-year event
Inflow = 116.74 cfs @ 12.18 hrs, Volume= 9.930 of
Outflow = 99.99 cfs @ 12.28 hrs, Volume= 9.930 af, Atten= 14%, Lag= 5.9 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 3.57 fps, Min. Travel Time= 9.4 min
Avg. Velocity = 1.11 fps, Avg. Travel Time= 30.3 min
Peak Storage= 56,653 cf @ 12.28 hrs
Average Depth at Peak Storage= 0.86'
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= 2,025.0' Slope= 0.0049 '/'
Inlet Invert= 591.50', Outlet Invert= 581.50'
Reach 207R: Channel 202
Hydrograph
IIIII � rt rt T fi r IIIII � rt rt rt T fi r IIIII � rt rt rt fi 1- -
1
1 1 1 1 1 1 1 1 1 1 1 1 1 1
■Inflow
130
i l
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iis.7acts
l l l I l l l l l l l l l l l l l l l l l l l l l l l l l l i i
❑ Outflow
120
-1 T T v F 1 Inflow 1Area=4$1.99ac
110
i
^ pp
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100
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50
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20
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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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 24
Summary for Reach 208R: Channel 202
Inflow Area = 247.345 ac, 0.00% Impervious, Inflow Depth = 2.86" for 25-year event
Inflow = 540.82 cfs @ 12.18 hrs, Volume= 59.049 of
Outflow = 522.01 cfs @ 12.26 hrs, Volume= 59.049 af, Atten= 3%, Lag= 4.8 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 6.25 fps, Min. Travel Time= 5.0 min
Avg. Velocity = 1.65 fps, Avg. Travel Time= 19.1 min
Peak Storage= 157,750 cf @ 12.26 hrs
Average Depth at Peak Storage= 2.27'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,514.04 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 90.00'
Length= 1,890.0' Slope= 0.0048 '/'
Inlet Invert= 581.50', Outlet Invert= 572.50'
Reach 208R: Channel 202
Hydrograph
1 I I-1_tttt- I I 1 1 I _t_tttt- I I I 1 I _tfitt- t-
-
� I I I I I I I I I I I IIIII I I I I I I I IIIII I I I I I I I
600 1 1 540.12 ors
550 I 11 522.01 cfs 4 L I I 1 1 I -tAnfaAArea=2-47.345-ace
500�.i7"I" IBI"AT1 � I 450/ ' 4 �-MaXVeT-42J fpsl­-
400
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a 250 11 1_ -1 1 L L L LL 1 1 IA_tL L L1,1 I I6 Al L L
1 1 1 I I 1 1 I I 1 1 I I 1 1 1 4�apacity =1 j 1I 1 �•10 IC SI
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150 - 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_
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50
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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 25-year Rainfall=5.87'
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 25
Summary for Pond 10OP: SW 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 = 62.63 cfs @ 13.46 hrs, Volume= 57.023 af, Atten= 90%, Lag= 82.4 min
Primary = 62.63 cfs @ 13.46 hrs, Volume= 57.023 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= 575.58' @ 13.46 hrs Surf.Area= 144,731 sf Storage= 1,226,570 cf (1,191,570 cf above start)
Plug -Flow detention time= 238.8 min calculated for 56.212 of (100% of inflow)
Center -of -Mass det. time= 223.2 min ( 1,072.2 - 849.0 )
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' 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 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=62.63 cfs @ 13.46 hrs HW=575.58' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Outlet Controls 62.63 cfs @ 14.35 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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 26
Pond 10OP: SW Detention Option 1
Hydrograph
1_11J 1 L 1_1_1
_
L I_1_I L_ _1 1 L L I_1_I L L
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/
'
/
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150
,
/
62.63 cfs
100
,
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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 25-year Rainfall=5.87'
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 27
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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 1111 PMP
Type // 24-hr 25-year Rainfall=5.87"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paoe 28
Pond 103P: SW Detention Option 2
Hydrograph
_
i
4.65 cfs pp
5 4.65cfs 11 1_1 _I I I I 1_1 _I I I I 1_ 1_1 1 1 1 I_ eak I�iv _ 6,661
1
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1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I
4 1 1 1-f++ 1 1 1-t+ L 1 1 1+ 1+ 1 1-1-1 1+ 1-1-1 -t + I 1 1-1
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 I I I I I I I
N g 111 1-t1L1 1 1ALL1 11 1 -1 L L 1 1 11LL1 1 1L1L1-
1I 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 I I
3 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 I I I I
0
2
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 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 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 I I I I I I I I I I I I I I I I I
1 �
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)
Ery

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 25-year Rainfall=5.87'
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 29
Summary for Pond 104P: SW Detention Option 1 - Pond 1
Keeping pond below 25 feet in height and 50 acre-feet of storage to avoid dam classification
Inflow Area = 247.345 ac, 0.00% Impervious, Inflow Depth = 2.86" for 25-year event
Inflow = 522.01 cfs @ 12.26 hrs, Volume= 59.049 of
Outflow = 72.04 cfs @ 13.61 hrs, Volume= 59.578 af, Atten= 86%, Lag= 81.2 min
Primary = 72.04 cfs @ 13.61 hrs, Volume= 59.578 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= 575.54' @ 13.61 hrs Surf.Area= 144,532 sf Storage= 1,220,146 cf (1,185,146 cf above start)
Plug -Flow detention time= 214.1 min calculated for 58.774 of (100% of inflow)
Center -of -Mass det. time= 199.8 min ( 1,071.3 - 871.5 )
Volume Invert Avail.Storage Storage Description
#1 565.00' 5,317,515 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
600.00 171,000 1,610.0 3,239,495 5,317,515 237,779
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 20.00
Width (feet) 50.00 56.00 80.00 80.00
Primary OutFlow Max=72.04 cfs @ 13.61 hrs HW=575.54' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Inlet Controls 72.04 cfs @ 14.68 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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paoe 30
Pond 104P: SW Detention Option 1 - Pond 1
Hydrograph
/
I l l l l l l
1-1 C T 7 1 1
l l l l
1 7 T T I
i I I I I
1-1 C T L I
I I I I I I I I I I I I I I I I
1 1 7 T T I 1 1 7 T L I 1 1 7 T
522.01 cfs
1 1
1 1 L L 1
1-1 1 L L 111
1 I II I -ta�+ T
IMInflow
tflow
"�I
aI
r ��� C1
conPrimardary
550
/
/7
1-1-1
1 1 1 1
1 1 1 1 F 1-1-1
1 pda-k-E V:j57j1,54-'F
500
1 1A4 1 1
14� 1-1
A 4 -k 1
1 �+ -k�I 1 14T0�'j1 IA -4
F+ Qr;pgp=11 i2121+�111* r,I
450
1-1A4 1 1
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A44 1
1 1-4- 11 14T 1 1 1-4T
400
/
/
350
N
V 300
/
/
/
+ +—I—I + i—I—I +
c
/
/
/
II IIII
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IIIIIIIIIIIIIIIIII
LL 250
200
/
/
1-1 -1 t
—1 rt fir 1-1
-1 t fir 1-1
—1 t t t I-1-1 rt t 1- I— 1-1 t t
150
/
/
72.04 cfs
/
72.04 cfs
100
/
so
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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 25-year Rainfall=5.87'
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 31
Summary for Pond 105P: Detention Pond Option 1 - Pond 2
Inflow Area = 47.194 ac, 0.00% Impervious, Inflow Depth = 3.66" for 25-year event
Inflow = 195.10 cfs @ 12.12 hrs, Volume= 14.410 of
Outflow = 15.18 cfs @ 13.33 hrs, Volume= 14.407 af, Atten= 92%, Lag= 72.5 min
Primary = 15.18 cfs @ 13.33 hrs, Volume= 14.407 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
Peak Elev= 617.93' @ 13.33 hrs Surf.Area= 2.385 ac Storage= 7.355 of
Plug -Flow detention time= 250.1 min calculated for 14.405 of (100% of inflow)
Center -of -Mass det. time= 250.2 min ( 1,080.3 - 830.1 )
Volume Invert Avail.Storage Storage Description
#1 614.00' 76.150 of Custom Stage Data (Prismatic) Listed below
Elevation Surf.Area Inc.Store Cum.Store
(feet) (acres) (acre-feet) (acre-feet)
614.00 0.000 0.000 0.000
615.00 0.460 0.230 0.230
621.00 4.400 14.580 14.810
626.00 5.880 25.700 40.510
632.00 6.000 35.640 76.150
Device Routing Invert Outlet Devices
#1 Primary 614.00' 18.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 614.00' / 613.50' S= 0.0100 '/' Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
#2 Secondary 625.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 25.00
Width (feet) 50.00 60.00 60.00
Primary OutFlow Max=15.18 cfs @ 13.33 hrs HW=617.93' TW=612.41' (Dynamic Tailwater)
L1=Culvert (Inlet Controls 15.18 cfs @ 8.59 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=614.00' TW=571.28' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 32
Pond 105P: Detention Pond Option 1 - Pond 2
Hydrograph
/
- - - -
I� 1 L L 111
- -
1 L L 11
- -
1 L I11
- - - - - - - -
1 1 L I11 1 1! 1111 1
195.10 cfs
I-1-1
7 I
-I7 � I -I- -+ + f- II-�11-1f I-1-11-+ +
19wArP4:'
1-1-1 7 1-1-1
7 7 71-1-1
7 7 L I�
71+11-141cjc
210
200
/ i / /
1 1 1 _
-
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P6ak EIbV � T7-.19f3-
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190
//
1 1A1 1 1
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180
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170
////
F
i l l F 1
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160
150
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1 L L 1-1-1
1 1 L 1-1-1
1 1 L 1-1-1 1 1 L 1-1-11 1
140
1 1
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-1 -+ 1
1 1++ 11 1-1+ 11 1 +
w130
i/i
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1 17 T T I 1 17 T L I 1 17 T
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v
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III t III
fi fi III
fi fi III
-t t III -1 t r III � +
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70
60
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15.18cfs
30
/ /
1s.18 cfs
20
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)
■ Inflow
■ Outflow
■ Primary
■ Secondary

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 25-year Rainfall=5.87'
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 33
Summary for Pond 106P: North 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 = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min
Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 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= 586.00' Surf.Area= 0 sf Storage= 0 cf
Peak Elev= 609.00' @ 0.00 hrs Surf.Area= 0 sf Storage= 0 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
#1 609.00' 1,184,473 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)
609.00 0 0.0 0 0 0
610.00 75,000 1,140.0 25,000 25,000 103,420
622.00 120,000 1,400.0 1,159,473 1,184,473 158,139
Device Routing Invert Outlet Devices
#1 Primary 609.00' 24.0" Round Culvert
L= 50.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 609.00' / 608.00' S= 0.0200 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf
#2 Secondary 620.00' 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=0.00 cfs @ 0.00 hrs HW=609.00' TW=608.00' (Dynamic Tailwater)
L1=Culvert ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=609.00' TW=608.00' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type // 24-hr 25-year Rainfall=5.87"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 34
Pond 106P: North SW Detention Option 3
Hydrograph
Ery
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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 25-year Rainfall=5.87'
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 35
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)
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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CI 25yr, 1111 PIMP
Type // 24-hr 25-year Rainfall=5.87"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paoe 36
Pond 107P: East SW Detention Option 3
Hydrograph
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 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 I I
1 1-t+L1 1 1ALLI- -L1L1 1 1 1 I 1
3.12 cfs
3.12 cfs �a �V= Lb 6
3
Storage =3066 Hof
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 I I
i 1 1 14+ 1 1 1-t+t-I- - 4 1 1 T- 1 1 1-t+ 1 1 1
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 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 I I I I I
u+ 2
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 I I I I
3 11 1-f+t-I 1 1-tfiFI- -�f-I 1 1-f 11 1-t+1 —1
o
a
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 I I I I
1 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
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
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)
Ery

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type // 24-hr 25-year Rainfall=5.87'
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 37
Summary for Pond 108P: RAB Ex. Spillway (no storage)
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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 25-year Rainfall=5.87'
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 38
Summary for Pond 200: RAB Outlet Pond (no storage)
Inflow Area = 47.194 ac, 0.00% Impervious, Inflow Depth = 3.66" for 25-year event
Inflow =
15.18 cfs @
13.33 hrs,
Volume=
14.407 of
Outflow =
15.18 cfs @
13.33 hrs,
Volume=
14.407 af, Atten= 0%, Lag= 0.0 min
Primary =
15.18 cfs @
13.33 hrs,
Volume=
14.407 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Tertiary =
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
Peak Elev= 612.41' @ 13.33 hrs
Device Routina 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 '/' 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=15.18 cfs @ 13.33 hrs HW=612.41' TW=565.70' (Dynamic Tailwater)
t-1=RCP Culvert (Passes 15.18 cfs of 217.15 cfs potential flow)
t-2=42" Culvert Steep (Passes 15.18 cfs of 98.69 cfs potential flow)
t-3=42" Culvert Shallow (Passes 15.18 cfs of 58.30 cfs potential flow)
t-4=54" Culvert (Inlet Controls 15.18 cfs @ 3.91 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=571.28' TW=565.70' (Dynamic Tailwater)
5=Emergency Spillway ( Controls 0.00 cfs)
Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=571.28' TW=565.70' (Dynamic Tailwater)
t-6=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 39
Pond 200: RAB Outlet Pond (no storage)
Hydrograph
I l 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
■ Inflow
15.18 cfsT
1518 cfs
F 1-1 I
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hrit,9•1
■ Outflow
■ Primary
15.18cfs
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■Secondary
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■Tertiary
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3
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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 40
Summary for Link 102L: Lake Wylie/Catawba River
Inflow Area = 215.660 ac, 0.00% Impervious, Inflow Depth = 3.23" for 25-year event
Inflow = 62.63 cfs @ 13.46 hrs, Volume= 58.082 of
Primary = 62.63 cfs @ 13.46 hrs, Volume= 58.082 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—I 1 1 1 I r r 1-1-1-1—I T 1 1 1-1-1-1-1—I T T
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■Inflow
70
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10 Primary
65
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35
— — — — — — — — — — — — — — — — — — — — — — — — —
LL30
7 TI 17777T7F 1T77T
/
25
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�
I I I I I I IIIIII I I I I I I IIIIII I I I I
20
15
1 1 1 1 1 1 1 1 1 1 1 T 1 1 1 T T 1 1 1 1 1 1 1 T T 1 1
10
—I—I 1-4 7 7 1 — —I—I—I 7 7 7 4 1-1-1-1-1-1 -4 7 T
5
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
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type // 24-hr 25-year Rainfall=5.87'
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 41
Summary for Link 104L: Lake Wylie/Catawba River
Inflow Area = 294.538 ac, 0.00% Impervious, Inflow Depth = 3.01" for 25-year event
Inflow = 87.19 cfs @ 13.58 hrs, Volume= 73.985 of
Primary = 87.19 cfs @ 13.58 hrs, Volume= 73.985 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
IIII T L L L i_ _.,1
L— —— T L— I II11I
L L 1 T
i
1-1_1-1-1 —1 -1 1 1 1 L L L I_ 1-1-1-1
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L L 1 1
95
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—II
90
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'�M�� I--I Q�
I I 1 -tnflow Area=1294M8 ac
85
i
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7 7 T 1-1-1-1-1-1
-4 7
80
i
I1' T LI111
7 7 T T L III111
7 T
75
i
II T L IIII
t T LIII
t
70
i
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i
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50
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777TT7FI
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35
— — — — — — — —
— — — — — — — — — — — — —
— — — — —
30
i
1 1 1
1 1 1
25
— — — — — — — — —
— — — — — — — — — — — — —
— — — — —
20
15
i
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)
■ Inflow
❑ Primary

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 42
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 Description
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 fps
10.2 850 Total
Subcatchment 102S: DA 102
Hydrograph
360
I l l l l l l l l l i l l l l i i i I I I I I I I I I I
340
335.39 ds
Type A 2 r
320
300
I4-h
280
1 1 1 1 1-1-1 T T T T T T T ICU nloff IArea�-2 �301T 379 -8f
260
240
_ _ 1_1_ _1 -1 -1 -1 -f 7 T T T r 7- T- 1_ _ 1_ I_ s_L``_,,II -11 -1 7 � QQ� T r r
--1-1--1-1-1-1-f7TTTTTT n4j�I�011 :p la
w2
200 00
11 11 ; fitfifir r i F�rdffDdpj *41 '�
c 180
1 1 1 1 1-1-1-t t t t t 1- � I I 1 1 1Fl8w Le1ngth=850t-
LL 160
— — — —I -1 -t -t t t t t t — I— 1— 1-1 —1 —1 —1 -1 * !
140
- -1-1 T T t T F I 1 1 1 1 1 —1 --1 !f
120
a�e�
I I- I � -1 -1 T 4 + t- t- I 1 1 1 1 1 --1 � -t -4 ��/C
100
- I- 1 -1 -4 -4 4 + + T 4- I- 1- 1- 1-1 -1 -1 -1 -4 -4 + + T 4
80
-I-I 1-1-4 -4 4 4-4-1- I-1-1-1-1-1-1-14-�4-4-��
60
4 � T � l
40Ii-
I���TTTT���I1����4�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

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 43
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
(min) (feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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
——--——— +rt�t-♦-}-—I—I—I-1-1-1-1 ��-+++
250
1 -T777TTT771 1 1 1-177TT7T7
240
230
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1 1 E6:2 cfs 1 1-1 1 1 1 1 T L L L 1 I I I I 1 1 1-1 1 1 1 1 1 L L L
220
- I- I- 1 1 -1 -1 A A 4 4 T T � �- �- I- I- I- I- - -I -I -A Type 41724-h1-
210
200
I I I -1-1-1 -T T T T T T T T I I �
�I�a• 'f='T
--A.3
190
180
1 I
-1-1- 1 _ -1-1 IAunoff IAr'ea---1$75,al J st
160
160
1 1 1 1 1 1 1 1 1 1 1 1 I� r 1 ,Iu�e� J.„t„�, a
�u �j V
150
w 140
I I -11-1111LLLL I- Ddj#h--5106rL
130
---I- -I -I t + + t f- - - - -I- -I -I +
c 120
���,yy��+ pt//�t�
1 7 T T T T T T T 1 Flow Len111��,61JVL
LL110
100
- - - - - - - - - - - - - - - - - - - - - - - -
I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I J I.0 Olin
1
!
90
- - I -I- 1 -I � -4 -4 4 4 T 4- 4- 1- 1- 1- 1-1 -1 -1 -1 �
80
1 1-1-1rt1TTTL11 1 1 1 1 1 1 1-11117M80-
70
- - I- -I -I I- I- - -I -I -I -I
60
- - - - - - - - - - - - - - - - - - - - - - - - - - -
50
II- 11�A-411TLL111I111111�1-4-44�LL�
40
- I- I- ' -1 -1 � t t t t 1- t t I- I- 1- 1-1 -1 -1 -1 -1 t t t t t t-
30
on—
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 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

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PIMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 44
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
I 11-1-1-1 t T T T r L L I I I 1 1 1-1 I 1 t T T T L L
210
1 1 T T 1
200
190
180
- - -
187.79
_ _
cf 7 T T F t
_I -I 1 I- I- - -I -I -1 TWe 11-Q4-h
-
170
- -11-
-11-� �-�OO �1 A�10f*q� of
160
— — —
— — — — — — — — — — — — — — — — —
150
— I— I— .
1 —1 J J -1 1 1 L L L L L IAlUno f # 1`A,'e' W� �24-5� at
130
I I-
44 T T I-0unoif IVp111ume;:i 6
w 120
- I- I-
1 -1 -4 -4 4 4 + T 4- ` ` I- 1- 1- 1-RUfliciff Ddpt1't -5�6rF
� 110
I I-
1 I-1-1 t t t t� t I IC -1 t t t t t T-t t
190
rt rt t rt fi fi fi I Flow Lwigth=15000t-
LL
-
80
— —
—1-1-1777T7777 1-1-1-1-1-1-1-1
70
11
M=00
60
50
40
— — — — — — — — — — — — — — — — -
30
20
1 1 1 1 1 1 L L I I I1 1 1 1 I J 1 1 1 1 L 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)
❑ Runoff

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PIMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 45
Summary for Subcatchment 105Sa: Area draining to 105
Runoff = 140.80 cfs @ 12.06 hrs, Volume= 8.944 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
924,750 80 Final Cover
924,750 100.00% Pervious Area
Tc
min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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 105Sa: Area draining to 105
Hydrograph
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 I I I I
❑Runoff
150
—— 140.80
cfs — � t t t t 1— t t-- I— I— I— I —I —1 —1 t t t t t t t t-
140
- I- I
I -I � -L -L 1- L- L- I- I- 1- 1- I - I -1 -1 -Jype ICI 24-b rL
1
_ I_ I_
I I
_ I� }{ II al l
I I I I I I I I I I I I I I F" 1111 C4
12020
110
1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 RU hdff Atecli192141750 sf
t t t 1- r t- - II- II- I-1-1-1 -1 -1-1 7 7 -7- r
100
-
n-r
1 -1 --1 A-4 4 T T T t- -�UnO# Va1lume�9a44 aU
y 90
Vr�
80
3
111" • I
LL 70
---
-----}pnD"F�I
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 E lOW L6rh tlh�11 0510E
-
1-1-1-17TTTT��IIII I�T���7AT�TT�
60
I
1 -1 --1 -4 4 T T T t- I I I I I - Fc=14.1- MiM
50
_
1T I I I LL 11 11 1 1 1 1-177 T
40
i
30
- 7 T T T T FI 1 7 7 T T T 7 7
20
-1 -1
-t-t t t t t t t- t I-I-I-I-I-1-1-1-1 t t t t t t t-
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)

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 46
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

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 47
Subcatchment 106S: DA 106
Hydrograph
360
IIIIIII
IIIIIIII
I I I i I I I I IIIIIIIIII I I I I I I I
IIIIIIIII
320
I�_%I A -24-hr
300
- -'I- �
{_I AType
II -II -� II II II II II �-ell���-I'
280
1
-- ----
--snW
1 1 uhvm 368�O7
f260
240
-�
��Olu�e&�•�7 �I
0 '1';:
220
wv 200
I
I I I I I I I I I I I 1
— ———R
T
180—
I— I— 1
I-1-T7TTTTTTT I T-
—1 -1 -1 1 T T T T T T T I— 1— 1— I— Clow E3gth=i593rc
u. 160
-
rt rt rt T T 1 r fi
140
-
_
fi+tt1 I i 440ifi�
120
1 -
t + + t i -CU=TU
100
--I
T++tt -
80
- -
-1 -4 -4 4 4 T T I- 1- 1- 1-1 -1 -1 -1 -1 -4 4 + + T T
60
-1-I
1-4-444 4- I-1-1-1-1-1-1-1-4-4-4-4-�
40
-1-1
I-1-1-1-1-1-1-1-� TTL
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Pace 48
Summary for Subcatchment 107Sa: Northwest AAB
Runoff = 225.25 cfs @ 12.06 hrs, Volume= 14.079 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
456,118 80 Final Cover
537,538 61 >75% Grass cover, Good, HSG B
773,974 75 Residential
1,767,630 72 Weighted Average
1,767,630 100.00% 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 fps
14.1 1,050 Total
Subcatchment 107Sa: Northwest AAB
Hydrograph
I I I -r t t t L L i i rt t t fi fi 77
250
�-1-1IITTT771 1 1 1 1 1-1777TT7TT
240
230
225.25 cfs 1 1 L L L L L I I I I 1 1 1-1 1 1 1 1 1 L L,. L
220
1 t t L L Type, 4I -24-h r-
210
200
I -1-1-177TTr77 1 1 % �a�L wi-
- - el 71�T 'I Fkoiof�4-1'
190
180
1
an
- I- 1-1- 1 -1 -4 -4 -4 4 4 4- 4- I U-noff 1FlrE��1 -767.,NO St
170
� 1 l ...
160
- - �-� u � - 1� i - �+17�
11 - 1
_150
y 140
b�,,y
— —1-1- 1 —I I— I— I— 1—Rdff Ddptft_�4A 6"-
130
— I— I— 1 —1 -1 -t -t t t t t t t- — I— I— I— I — —1 —1 -1 � � -t t t t t t-
c 120
11— —1 —1 1 7 7 T T 1— 1— IF-Iowi Length=t,050!
M110
100
- - - - - - - - - - - - - - - - - - - - - -
1 1 1- 1 -1-11 1 1 L L L L I I I I I I 1-] �
90
.
-1-1-1 1-1 -4-4 4 4 4- 4- 4- 1- 1- ! T
80
1 1- 1 1-1-1-1 7 7 T T L 7 7 1 1 1 1 1 1-1 7 7 7 IMp2-
70
- - - -I -I -I -I
-I -I -I
60
I- I- I-
1 -
50
- I- I- -1 -1 -4 -4 4 4- 4- 1- I- 1- 1- 1-1 -1 -1 -1 4 4- T T
40
- I IIIIrtrtTTLrr- 11 1 1 1 1 11-11rtITfi-rr
30III
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1
20
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 49
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_I_I--I-I-I
---------I-I-I ■Runoff
80
75
- I-
78.21 cfs I
I- -I -I -I -I -I 1 1 1 1- 1- ITy a 1lll��i�
70
1111
111 1 7 T T T T TRl
ll4100jeirin"lfr40"
65
I I I rt rt++ fi 1RuhdiffMelA:Zl131700 ti
60
�
+ t- t � � + + I I I I 1 1c 1 11
55
1
`
1 1 1 1 1 A-4-4 4+ � R u[noIf f M-Q =##41 �16(�
L
LL(nl00IOe�T�I�T"I"�'
45
I_ I_
I_ -i 1 1 1 L L I L
c 40
U.
1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 F16W IL6ftth Oa (��101
----------------
35I_
II
1 1 ICc=141 min
30
25
1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
M—A
T -77
20
I I 7++T T ++ 1 1 1 1 I 1 r
� III
III I I� rt rt rt++ t fi fi fi rr- IIIIIIII I I I
15
I I -1-1+++ t t i-+++ I I 1 1 1 1 1 1 1 1+
10
---
-1 -1 -1 -1 -4 -4 -4 4 4-4- 1-1-1-1-1-1-1-1-1-1-4
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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 50
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 fps
9.7 750 Total, Increased to minimum Tc = 10.0 min
ii
Subcatchment 108S: Area draining to 102
Hydrograph
11 1 1 1-1 rt rt t t t t t t t
I I I I 1 1 1-1 t t t t t t t t
161.21 cfs —1 —1 —1 -+ t t
1 —1 � —f —� t t +- +- }—
�-A-4 4++
1 1 1 1 1 1 1 a pe N 24-h f-
1111_
Y-Pa
In. 4
1 1 1 1 1 L L L L L 1-
Rlift -ff-Me'a192C571 tf
I_ _I _I I I I I I I
TMunloff1VoWme--18-942 of
III I I I I 1 1 I I I
nf I I I
_ _ I
I I _1
I I I I I I I I I I I
-1-I 1F�IbVV ILO-hspth17501
1 1-I-I-I I I I I I I i I I I
� -1 -1 7 7 T T T r T-1
I -,�l G.e mim
- -
-I _1 _t -t 7 7 T T r r r- I-
I- I- I- I -1 -1 -1 -1 -1 rt 7 -Ofj�
00 1-
- -1
-1 -1 -1 -1 t t t t t t- t- I-
I- 1- 1-1 -1 -1 -1 -1 t t t t t t t t-
- I- 1
-1 -1 -4 -4 + + + + I-
1- 1- 1-1 -1 -1 -1 --1+ + + + + +
- I- I-
I -1 � -4 -4 4 4-
1- 1- 1-1 -1 -1 -1 - 4 T 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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 51
Summary for Subcatchment 201 S: DA 201
Area that drains using HydroCAD catchmentarea +38.75 acres to the southwest of the basin by the pond
Runoff = 394.84 cfs @ 12.22 hrs, Volume= 36.831 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
1,200,000 60 Woods
1,310,000 75 Residential
2,239,000 74 >75% Grass cover, Good, HSG C
4,749,000 71 Weighted Average
4,749,000 100.00% 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
Subcatchment 201 S: DA 201
Hydrograph
-------I�rtrtrtrt
i i-rr I--I-1-1-1-1-1-I-1-1rtrtrttfifir
440
�-1-f77TTT77I 1�777 T TTTT
420
400
394.84
I I
cfs I I I I I I I I I 1 1
* �f
I I I I Type 11 Y4-hr-
380
360
ri
LLLLLLL I al Fjojoj*q
340
1 IA-4-444L I I flrl /
LLL
320
I I
nnn.S
1 1�-A-4 4 4+ L L L 1 11'�Ioff 1Arem--415/ 49,OM -sf-
300
I
II
-
V1 rt I�t3t1�a280 1-1-1-1-f7TT�
1I
1I -1I rtI rtI -rI rtI TtI tI LI 7-LI
260
H
v 240
II
�� "
'--R"dff Ddpth--AA.05
LL200
- II_ I_
I I I I I I I I r I I I I I I I I I
_I J 1 1 L L L L L I_ 1_ 1_ 1_ 1 _ HOW LLeJrig 750L
180
- I- I-
-I -L -L � L L I- I- I- I-1 -1 -1 -I I �!
160
- I- I-
1 -1 -4 -4 4 4 4- - 1- 1- 1-1-1- I -I IT
140
- - I-
-1 -1 1 1 rt rt t -r fi f- f- I- I- I- I- I -1 -1 -1 -1 -1 rt rt 1M71r
120
1- 1- 1-1
-1 -1-T-f 7 T T T T 7- 7 I- 1- 1- 1-1 -1 -1 -1 -1-1 7 7 T T T T T
100
I - -
1
1 1 1 1 I 1 1 1 1 1 1 1 1 1
80
-
60
an
III
IIIIIIII
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 52
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 = 176.39 cfs @ 12.18 hrs, Volume= 14.781 af, Depth= 3.62"
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
1,020,000
60 Woods, Fair, HSG B
1,114,000
74 >75% Grass cover, Good, HSG C
2,134,000
67 Weighted Average
2,134,000
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"
2.4
100
0.0200
0.71
Shallow Concentrated Flow, shallow
Woodland Kv= 5.0 fps
0.8
100
0.1600
2.00
Shallow Concentrated Flow, shallow
Woodland Kv= 5.0 fps
24.0 300 Total
Subcatchment 202S: DA 202
Hydrograph
—— I_I_I_I 1 —1 —1 1 1 1 1 1 1 1 1 I — 1111-1-1 —1 —1 —1 1 1 1 1 1 1 1
176 39 cfs 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 * 1 1 1 1 1
I— — —I —I —I Type 11-24-hr
--- ----------------
-----------
1- 1 1 1 1 1 1 1 1 -%llnoff Arow=2 134 000 -st-
I I I I I I I I 4-I1 11 1
---- ----------------------------
dff
I_ I_ I I I rI I I I I�+ I I1h I
J J J J J J IEIQM[ L ffi=300'
1 —1 J J J J) I I I J J I_ 1_ I— I-1 —1 —1 —1 _1• 4�
I- IJ-1-111111LL1 1 1 1 1 I 1 11 �J J
_I _I J 1 J J 1 11 J J J jACM= 7
I- IJ J J J J 1 I L L J 11 11 1 1 -1 -1 J J J 1 1 J J L
_1-1-1_1JJJJJJILJLI_I-1-1-1-1-1—IJJJ_1 1 1 1
- J J J J J J I L L J I 11 1 1 1 1 I J J -t -t L L L
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PIMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paoe 53
Summary for Subcatchment 203S: DA 203
Runoff = 229.87 cfs @ 12.06 hrs, Volume= 14.531 af, Depth= 4.72"
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
920,000 74 >75% Grass cover, Good, HSG C
690,000 80 Final Cover
1,610,000 77 Weighted Average
1,610,000 100.00% Pervious Area
Tc
(min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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 fps
14.2 700 Total
Subcatchment 203S: DA 203
Hydrograph
250
- I- I-I-1-1-1
-1 -4 -4 4 4 4- 4- 4- - 1-1-1-1-1-1 -1 -1 -4 -4 -4 4 4- 4-
240
229.s7cts
rt t T r rt T
2
1 1
-
1 I 1 I I I I II 1t1 l� r
230
20
210
- - 1- 1-
rF
-1
01 �I"T
00
-t 7 t -r -r fi r 'I ��� "
190
180
�I +
/� /`�I'/�T
] LRUn1off 1Arew -1 �1%000 tf:
160
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-1
1- 1 1
1 -1 rt rt t T t 1- af
y 110 40
V 140
1 1 1 1 1 1 1 1 1 1 R�ciff Ddpt 4.- 2r1
130
- 1- 1- 1-
-I -I I- I- I- I- - IC -I -I �^�n�
_0120
I I I
�4���
11-1rtrtrttttfi�r- I I I I HOWLeingt�r7OOr
u 110
100
I -
4.9 � I;
- �111
9
90
- - 1-1
1 -1 -4 � 4 1- I- I- I- I-1 -1 -1 -1 �
80
-
-I -11rttttt1-tr- 1-1-1-1 11ttt7M=77-
70
1
I I I I I I I I I I I I I I I I I I I I I I 1 1
60
50
-
- - I-
-1 � � 1- I- I- I- I-1 -1 -1 -1 � 4 L
40
I I-
1-1-1-t t t t t l- t� I I I 11 1 1 1 -1 t t t t t
30
- -I
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 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

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 54
Summary for Subcatchment 204S: DA 204
Runoff = 144.33 cfs @ 12.13 hrs, Volume= 10.939 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
1,131,000 80 Final Cover
1,131,000 100.00% Pervious Area
Tc Length Slope Velocity
min)
(feet)
(ft/ft)
(ft/sec)
9.5
100
0.0200
0.18
2.5
150
0.0200
0.99
0.8
200
0.3333
4.04
7.3 1,500 0.0067
20.1 1,950 Total
Capacity Description
(cfs)
3.40 108.91
Sheet Flow,
Grass: Short n= 0.150 P2= 3.41 "
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
Trap/Vee/Rect Channel Flow, Channel south of landfill
Bot.W=10.00' D=2.00' Z= 3.0 '/' Top.W=22.00'
n= 0.045
Subcatchment 204S: DA 204
Hydrograph
160--1-1-1-1 L L L L I- I- I- I- I - I -I -IL L L 4 1 L L L
150 1 1 1 1-.33 cfs 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
140 II1]24�-hh
130 T T T T T T T01 �I—T" ' I'i��f—I',T
120 -1 + + + + + + + 1-Rt11n1off 1Ar ew--1;131+ (W ist
110�7I L L L
100 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1unp I� Ql1u�� 01•�30 ;a--- ---------------------------
w 90 ft i(iff Deipth--S.OV
V 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
LL soo T -1 -1 T T TT T T T 1- 1- 1-Flow LeNt17=#,95Or
60 1 1 1_ 1 1-1-1-1 1 1 1 L L L L I I I I 1 I I -1 i'L
50 _ _I _I _I _ I_ I_ I_ _ _I _I _I _I 1ZN =80-
40 1
30
-T -fTTTTTTTI-
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

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen Cl 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC 155
Summary for Reach 102R: Ditch 102
Inflow Area = 155.968 ac, 0.00% Impervious, Inflow Depth = 4.23" for 100-year event
Inflow = 660.68 cfs @ 12.04 1 Volume= 54.945 of
Outflow = 587.28 cfs @ 12.11 hrs, Volume= 54.945 af, Attei 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 '/'
Inlet Invert= 608.00', Outlet Invert= 595.00'
Reach 102R: Ditch 102
Hydrograph
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 I I I I I I I
ITTTTTTI ITTTTTTTI ITTTTTTT
■Inflow
700
ssosa crs
III 4 T T T IIIII T -t 4 T T T �- IIIII T -t 4 T T �_ �_
1_ 1 I I 1_ 1 Infl@w ,Ar_ea1=1_56.9C8_a-c_
❑ Outflow
650
_ _1 - _ _1 _1 _1
�•�II•I�•T�"I" I1�I q 4600
-IIlsa2aors=T
I I I r-"
550
1-1-1- TTTTTI 1-1-1 —1TTTTTTFMaX_Vet�s./9f_S
500
-k I-I---144++t- I I 1 1 1T-t4+6�
n=0._nJ_
450
400�}
i l
•I-�•I-
c 350
rt T T T r I- I- -I S�O<0064 T-
LL 300
1 -4 � � I-I-1-1-1 � �4
l Caplacity=11A9116.164 icfsl
250
,
200
150
4t
t t t- r 1-1-1-1-1 -1 rt rt t t 11-1-1-1 rt rt fi I
100
-1-1 -1 -4����1-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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 56
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 '/'
Inlet Invert= 588.00', Outlet Invert= 579.00'
Reach 104: Ditch 104
Hydrograph
-1-1-1-1 -1 rt T T l- r- 1-1-1-1-1 7 7 rt T T l- r- 1-1-1-1-1 T -t -r T T r
210
200
/
/ 1
-1I-1 67.79 o1s I 1 1 1 1 1 1 1--I-I-I 1 1 1--I-I-I
1l l
t�
r y� nflOw
F I =481. Wft
190
1 /+f,r6 1
180
170
/
/
I 1pp� 1
1 1 _t _L _L L L L 1-1-1 I-1A1 LL OW-
1 1ss.zzcfs 1� 4- t 1 1-1-1 -1 --1 4 1 V4 OW OP
160
150
1TttLI 1-1-1 -1-1rt rt t T t -f�Xl 1� '�
140
/
1TTTL1 ITIITTTLI ITh:jo 2,7L
130
/
ci 120
110
/
/
-I-I - -I-I-I -I-I-I
0 100
/
-I-I- -I-I-I----L=_1�5�.Q'I_
-I-I_---I -I -I -I-I-I@ -�Ij �/I_
��L
LL g0
/
1- 1- 1 L L I- I- -I -I L L I- I- -IvZI
80
/
II-4
4 T 4-III�F"�'Ifi5�
70
/
I -I -I t t +
60
/
II- 1 T rt fi LIII rt 1 T rt fi LIII rt rt T fi--
50
/
F 1 1 11 T T F F T 1 -1 T T F F T 1
40
/
30
/
20
/
"T T F T 1 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)
■ Inflow
❑ Outflow

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 57
Summary for Reach 105: Ditch 105
Inflow Area = 21.229 ac, 0.00% Impervious, Inflow Depth = 5.06" for 100-year event
Inflow = 140.80 cfs @ 12.06 hrs, Volume= 8.944 of
Outflow = 125.79 cfs @ 12.11 hrs, Volume= 8.944 af, Atten= 11 %, Lag= 3.4 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 5.53 fps, Min. Travel Time= 6.0 min
Avg. Velocity = 1.26 fps, Avg. Travel Time= 26.3 min
Peak Storage= 45,252 cf @ 12.11 hrs
Average Depth at Peak Storage= 0.71'
Bank -Full Depth= 4.00' Flow Area= 168.0 sf, Capacity= 2,571.90 cfs
30.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 54.00'
Length= 1,990.0' Slope= 0.0151 '/'
Inlet Invert= 618.00', Outlet Invert= 588.00'
Reach 105: Ditch 105
Hydrograph
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 I I I I I I I
F 1 7 7 T T T F 1 7 1 1 F F
■ Inflow
150
I iao.eoors rt fi r I I I _t_t rt+ fi r I- I ♦_t rt rtnfi r- r-
1 1 1 4 + + I 1 1 1 -t 4 [nf1ow,A ea=- 2
Outflow
140
1+.22S-ae-
130
i l
I 1 1 + L L 1IIII � � � + L II I � 1
125.79 cts ^^ pp
I_ �+_ 1+P r_ 1 1 I_
_ _ _I _I _V�h _
120
1 1 1 1 1 I lA�,��l ` 0 0-0
110
1 1 1 1 1 1 1 1 1 1 1 1 �1 �/ 17 �J
100
1 1 I 7 T T T L 1 1 1 1 1-1_t_f T T T L 1 1 1 1 1Th�0.0 F
90
-
���♦ fiAtnt t- �
- T I- L=-1
80
,-990.0'�
0 70
LL
60
I 1 1 1 �!, �J 0 OW
50
40
rt+fir I I I rtrtrt+fir I I I-1rt-tfi--
30
/
1+ 1- 1-1-1-1-1 -4-4 1 1-1-1-1 -4 4 1
20
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paoe 58
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 '/' Top Width= 57.00'
Length= 1,210.0' Slope= 0.0050 '/'
Inlet Invert= 614.00', Outlet Invert= 608.00'
Reach 106R: Ditch 106
Hydrograph
I_ I_ 1_ 1 _1 J 1 L L L L I_ 1_ 1_ 1 _1 L J 1 L L L L I_ I_ I_ 1 _1 L J 1 L L l
i t 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_I I I I I
360 i 1 11 331.14 CIS I I I I I I I I I I I I I r� MII I I I I I I I I I I I II
340 , _ 320.26 CIS _ I _ I _ I _I _I I li l i @�/ IAr_T ��=p 19 Wj�� ♦ 1 1��_
1.
300
20 I_ ____
260 I I I I I I I I I I I I I I I WOO 70p fosil
240 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 n=0- 02-71
220 , I_
y --- IS 200 I _ _ _ ---I I -I1�7- 1==1v1a,2!0.0'
I
180 II I I�II I I I I I I_ I� b/vIc 1LL 60 I
- - - - - - - - - - - - - - - - - - - - - - - - - - -
140 i l l l _ 00 1H� 1i _ _ _ 0200l �� 01
120 _' 1 _ I_I_I _ _ _ _ _
100
80
60
40 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)
■ Inflow
❑ Outflow

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 59
Summary for Reach 107R: Ditch 107
Inflow Area = 52.372 ac, 0.00% Impervious, Inflow Depth = 4.36" for 100-year event
Inflow = 303.42 cfs @ 12.06 hrs, Volume= 19.048 of
Outflow = 295.25 cfs @ 12.09 hrs, Volume= 19.048 af, Atten= 3%, Lag= 1.7 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 9.10 fps, Min. Travel Time= 2.6 min
Avg. Velocity = 2.03 fps, Avg. Travel Time= 11.5 min
Peak Storage= 45,422 cf @ 12.09 hrs
Average Depth at Peak Storage= 0.98'
Bank -Full Depth= 4.00' Flow Area= 168.0 sf, Capacity= 3,451.02 cfs
30.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 54.00'
Length= 1,400.0' Slope= 0.0271 '/'
Inlet Invert= 628.00', Outlet Invert= 590.00'
Reach 107R: Ditch 107
Hydrograph
I I I I I
III
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 I I
rt rt+ fi rIII rt rt rt+ fi rIII rt rt rt fi 1
■Inflow
320
I— 303.42
I
cfs
fi+t- IIIII��fi+t- I/�IIII�fi'fi�t-�
❑ outflow
�
- 29s.2scfs
-4 -4-1- I-I-1-I-I MowIArea=52.3 2--�
300
280
pp� }}�� •r �Q
J J J L L - -I-I -I J J -LAVA L��+YM•
260
,
- I- I
- - -I -I -I � � _i00I—P.1
0 fos
220
,
I I�W0251
200
180
y30
T F 11 -
1 I I 1 1 I I 1 1 I I 1 1 I I 1 1 I I 1 1 I I 1 1 I I 1 1
I I I I I I I I I I I I IL=1,A00.0'I
160
-
0�
`L 140
rtrt+fir rtrtrt+fir 1S1= 1�
120
i
t + t- � IIIII � _t _tI}�/I I �
Cr
`ITT S'-
1-11-
4 + + I I 1 1 1+-4 4 I� �I �'
100
--
4�+tI 11 1 144�+t-�-I 11 1 1444- -
80
A
JJLLL1-I-I-IJJJJJLLLI-I-I-IJ_L1 I I
60
i l
40
i l
l l
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 60
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 '/' Top Width= 42.00'
Length= 950.0' Slope= 0.0442 '/'
Inlet Invert= 650.00', Outlet Invert= 608.00'
$ \
Reach 109R: Ditch 105
Hydrograph
- 1-1 -1 -1 -1-T 7 T 1- r- 1- 1-1-1 -1 7 7 rt 7 T 1- r- 1- 1-1-1 -1 7-7 rt T 7 r
180
_1_1 -I _1 rt rt rt fi r I _1_1 -I-Irt rt rt rt fi r I I I I I-Irtrtrtfi1-r-
■Inflow
s1.z1 cf s rt rt rt fi r l III I� rt rt rt rt fi r l III I� rt rt rt fi1-r
❑ Outflow
170
s
— , 158.57 ci* fi r - - — rt ��10W Ar�21.225-a c-
160
150
�
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140
130
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i
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120
i
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110
i
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100
,
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0 90
1 1- -4 t I 1-1-1 I�-L t-4 t-I I I I I
LL 80
i
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70
i
60
=1-I 1 1 1 1 1 1-1-1-1-11 1 1 r"7"1"IIT '1'1"L
50
,
IIII IIII
40
,
_I IIIIIII I
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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen Ci 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC 161
Summary for Reach 20613a: Channel 201
Inflow Area = 109.022 ac, 0.00% Impervious, Inflow Depth = 4.05" for 100-year event
Inflow = 394.84 cfs @ 12.22 hrs, Volume= 36.831 of
Outflow = 377.43 cfs @ 12.29 hrs, Volume= 36.831 af, Attei 4%, Lag= 4.2 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 5.71 fps, Min. Travel Time= 5.3 min
Avg. Velocity = 1.55 fps, Avg. Travel Time= 19.3 min
Peak Storage= 118,965 cf @ 12.29 hrs
Average Depth at Peak Storage= 1.86'
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= 1,800.0' Slope= 0.0050 '/'
Inlet Invert= 597.00', Outlet Invert= 588.00'
Reach 20613a: Channel 201
Hydrograph
IIIII � rt t T fi r IIIII
� rt rt t T fi r IIIII
� rt rt t fi 1- -
/
I
I
440
420
400
/
/
— — 394.84 cfs — — — — —
_I_I_ _ _I_I_I_I
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— — — — — — — — — — — — — — — — — — -
xxI_I_I � I_
I I 1 J ffi AreaZlID9.D�as�
377.43cfs
— — -I —i -L _W
380
/
- - _t t T t- k- I
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360
/
I I I rttT r
-1 _t _t
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30
/
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320
300
/
-----
5-
280
/
-I-I_ -
- -I-I -I - - -I-I
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260
-I-I- 4 4- I-I-1-1-I
-4 -4 -4 4- 1-1--I-I�
4.14
y
V 240
t fi t--I-I-I
+J
3 220
/
- -I rt T T 1- r I-
I-1-1 -I 7-t -rT T 1- r I- I - I -I
&�O V05O I~��
LL 180
�
160
IIC1=I��I•1�7R�
140
/
11 1- -4 TL I
1-1-1 I�_t-4 TL I I I
1 I�_tJ !-
120
/
-1-1 + 1- I-I-1-1-I
-4 - + 1- I-I-I-1-I
-4 -4 -� + 4 f
100
/
-1-1 t t t t- r I-I-1-1-I
t rt rt t t t- r I-I-1-1-I
t rt rt t I
80
/
60
- - - - - - -
- - - - -
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)
■ Inflow
❑ Outflow

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 62
Summary for Reach 20613b: Channel 201
Inflow Area = 161.394 ac, 0.00% Impervious, Inflow Depth = 4.15" for 100-year event
Inflow = 543.96 cfs @ 12.16 hrs, Volume= 55.879 of
Outflow = 535.48 cfs @ 12.21 hrs, Volume= 55.879 af, Atten= 2%, Lag= 2.8 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 6.48 fps, Min. Travel Time= 3.2 min
Avg. Velocity = 1.69 fps, Avg. Travel Time= 12.4 min
Peak Storage= 104,140 cf @ 12.21 hrs
Average Depth at Peak Storage= 2.25'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,861.70 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 90.00'
Length= 1,260.0' Slope= 0.0052 '/'
Inlet Invert= 588.00', Outlet Invert= 581.50'
Reach 20613b: Channel 201
Hydrograph
- I-1-1 -1 -4 + + 1- I- 1- 1-1 -1 + -4 -4 + + 1- I- I-I-1 -1 + -4 4 + +
� 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 I I I I I
600
550
- - 543.96 cfs
A e� a('_
� 1�
- 535.48ds - T I I I —t -4�nflow rea1=11_61.394_
500
IBI"AT��-
450
-' I- I- - -I �_MaX V ef_-6M tp-sl­-
400
0. 25
N350
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0300
7TTTL1 IT_t_fTTTLI 1S-��01.0052 -
LL 250
1
I I I I IIIII I I I I aI pI hI I I I II INI I
1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 14city=19,8C1/ 5
200
I— 7TTTLI 1 1 1 IT_t_fTTTLI 1 1 1 IT_t7TTL
150
-IIIIII _
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 I I I I I
100
II- rt rt fi LIII rt rt rt rt fi LIII rt rt t fi L-
�
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 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 63
Summary for Reach 207R: Channel 202
Inflow Area = 48.990 ac, 0.00% Impervious, Inflow Depth = 3.62" for 100-year event
Inflow = 176.39 cfs @ 12.18 hrs, Volume= 14.781 of
Outflow = 156.89 cfs @ 12.26 hrs, Volume= 14.781 af, Atten= 11 %, Lag= 5.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 4.20 fps, Min. Travel Time= 8.0 min
Avg. Velocity = 1.21 fps, Avg. Travel Time= 27.9 min
Peak Storage= 75,644 cf @ 12.26 hrs
Average Depth at Peak Storage= 1.12'
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= 2,025.0' Slope= 0.0049 '/'
Inlet Invert= 591.50', Outlet Invert= 581.50'
Reach 207R: Channel 202
Hydrograph
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 I I I I I I
■ Inflow
190
/
/
176.39 cfs I_
❑ Outflow
180
I 1 1 1 1 1 1nf16W11
11e�=4a.990Lab-
/
- - -1 _ - - -I -I -I
170
/
11 -1TLLLL L 1 1 1-1A I AL LL I I 1- 1
156.89 cfs ^ p
Vt
160
/
1 1 - _4T_LLLI I I I I_1_t_4
150
/
-----I-I-I
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140
——-44 L
130
1- 1-1 4 4+ 4 1- 1-1-1 -1 h�0.025�-
120nt�t
is 100
;
T t I- 1-,-, -1 -1-f-t t T t-r I- 11 1 L�,025.0'r
c
-I-I rt rt t i r 1-1-1-1-1 -1 rt rt rt t 1- r 1-I-1-1-1 rt rt-r r
_
LL
_ /�
I 7TTLL1 IT_t_fTTLLI I�I I 1—�][�3�
80
70
/
/
+VF
�IR�T�117TT��T �1"�
60
/ 1
T`r
50
/
40
/
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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 64
Summary for Reach 208R: Channel 202
Inflow Area = 247.345 ac, 0.00% Impervious, Inflow Depth = 4.13" for 100-year event
Inflow = 815.30 cfs @ 12.17 hrs, Volume= 85.191 of
Outflow = 790.07 cfs @ 12.23 hrs, Volume= 85.191 af, Atten= 3%, Lag= 3.9 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 7.14 fps, Min. Travel Time= 4.4 min
Avg. Velocity = 1.81 fps, Avg. Travel Time= 17.4 min
Peak Storage= 209,019 cf @ 12.23 hrs
Average Depth at Peak Storage= 2.87'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,514.04 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 90.00'
Length= 1,890.0' Slope= 0.0048 '/'
Inlet Invert= 581.50', Outlet Invert= 572.50'
Reach 208R: Channel 202
Hydrograph
1- 1-1-1 -1 -4 -4 � 4- 1- 1- 1-1-1
-1 -4 -4 - 4- 1- 1- 1-1-1 -1 -4 -4 4 4- 4- k
■ Inflow
11 815.30 cfs 4- t I I
1 1 1 4 4 4- 1- I- I I 1 11 4 4 4- �- �-
❑ Outflow
1- 1
4 � � 1- 1-1-1
4 4inflowI-�W� rea= 47h�345-ac-
790.07cfs
-1 _4
III
4 � 4- t- I III
I 4 4 1D1e��'�
I I
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700
,
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650
i
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600
i
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550
i
1 1 1
1 1 L L L L I 1 1 1L1111LLL1 I ILA Jj_tl Ja.lpt-
IS 500
i
-I-I_
H I L L LI-1-1-11 1 1 1 1 L L LI---ILJ-7I1v��J 7 L
3 450
_I_I_
1 1 1 L L I_I-1-1-11 1 1 1 1 L L I_I-1-IS::JOt.00461�_
0
LL 400
i t
I I
1 1 L 1 11 1 1 1 1 1 I I I� I I I IC I II IC� I I I
350
- I-
1 1 1 L L L 1_ 1 _1 -1 1 1 1 1 Wao-A 1 ;5fi�1V LC SL
300
_
1111_1 L1-1_1-11_I _I 111_1 L1-1_1-11_I _1 1L1
250
i l
200
150
100
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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 65
Summary for Pond 10OP: SW 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 = 4.46" for 100-year event
Inflow = 940.07 cfs @ 12.08 hrs, Volume= 80.093 of
Outflow = 74.36 cfs @ 13.65 hrs, Volume= 80.623 af, Atten= 92%, Lag= 94.1 min
Primary = 74.36 cfs @ 13.65 hrs, Volume= 80.623 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= 579.63' @ 13.65 hrs Surf.Area= 163,425 sf Storage= 1,849,932 cf (1,814,932 cf above start)
Plug -Flow detention time= 300.7 min calculated for 79.808 of (100% of inflow)
Center -of -Mass det. time= 289.0 min ( 1,126.5 - 837.6 )
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' 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 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=74.36 cfs @ 13.65 hrs HW=579.63' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Outlet Controls 74.36 cfs @ 17.04 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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 66
Pond 10OP: SW Detention Option 1
Hydrograph
-I T
r 1-1-1
T T TI-1-i
I. -1-1
T T r1-17 T T 1-1-17 T r 1-1
/I
11
1 1
I I 1 1 I I
I I I I Fi
I 11 1 1 1 1 F i-i
/
/
940.07cfs
1 L II
1 LII
L 1 L II
^ rqqa- C
`4
1,050
/ ,
- 4
-1 -1 7 T 1-1
-4 4 I-
-I - �T='I
1,000
/ / , /
-I -t
1-1 rt -r 1-1
-1 rt 1-1
-1 rt T r-fta r MeVr�iM9 631
950
////
11 I I 1 1 1 I-1 1�TJ
850
///
I_I J 1
1 _I 1 1 L 1_1
J 1 L 1-1
_I --1tp��r1 �_ 1
800
//,
—I�
1-17 T 1-1-4
4 1-1-17
T 1-14-1-1-1-4 1-1
750
//
11 1 t
11 t t t 111
t t 111
t t r 11 t t t 111 7 t r 11
700
//
I_1 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_1_1
650
/w
600
/
550
/ / / /II
IIII
TIIII
c 500
/ / / /I
+
+ + +I
+ + 11
1 + t 11 + + + 1 11 7 + 11
M 450
/
1J7
1 1-1
1J771
1 1-117TT1 1-17Tr1 1
400
/
350
///
300
//
I I L
1 1 L 1 L 1
1 J 1 L 1
1 1 L T L 1 1 L 1 L 1 1 1 7 L L 1 1
250
/ /
—I
+ + + 1-1
-1 + 1-1
—1 + + �- 1-1 + + + 1— 1-1 7 + � 1-1
200
/
74.36cfs
150
/ ,
74.36 cfs
100
/
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)
■ Inflow
■ Outflow
■ Primary
■ Secondary

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 67
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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 1111 PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paoe 68
Pond 103P: SW Detention Option 2
Hydrograph
_
i
4.65 cfs pp
5 4.65cfs 11 1_1 _I I I I 1_1 _I I I I 1_ 1_1 1 1 1 I_ eak I�iv _ 6,661
1
/'I I I I I I I I I I I I �toragei=a71� bbb act
J 7
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I
4 1 1 1-f++ 1 1 1-t+ L 1 1 1+ 1+ 1 1-1-1 1+ 1-1-1 -t + I 1 1-1
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 I I I I I I I
N g 111 1-t1L1 1 1ALL1 11 1 -1 L L 1 1 11LL1 1 1L1L1-
1I 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 I I
3 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 I I I I
0
2
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 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 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 I I I I I I I I I I I I I I I I I
1 �
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)
Ery

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 69
Summary for Pond 104P: SW Detention Option 1 - Pond 1
Keeping pond below 25 feet in height and 50 acre-feet of storage to avoid dam classification
Inflow Area = 247.345 ac, 0.00% Impervious, Inflow Depth = 4.13" for 100-year event
Inflow =
790.07 cfs @
12.23 hrs,
Volume=
85.191 of
Outflow =
87.45 cfs @
13.75 hrs,
Volume=
85.721 af, Atten= 89%, Lag= 91.0 min
Primary =
87.45 cfs @
13.75 hrs,
Volume=
85.721 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= 579.94' @ 13.75 hrs Surf.Area= 164,889 sf Storage= 1,900,313 cf (1,865,313 cf above start)
Plug -Flow detention time= 269.4 min calculated for 84.917 of (100% of inflow)
Center -of -Mass det. time= 258.9 min ( 1,117.2 - 858.3 )
Volume
Invert Avail.Storage
Storage Description
#1
565.00' 5,317,515
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
600.00
171,000
1,610.0
3,239,495
5,317,515
237,779
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 20.00
Width (feet) 50.00 56.00 80.00 80.00
Primary OutFlow Max=87.45 cfs @ 13.75 hrs HW=579.94' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Inlet Controls 87.45 cfs @ 17.81 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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CI 25yr, 100yr, PIMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 70
Pond 104P: SW Detention Option 1 - Pond 1
Hydrograph
/
l
u l l
■ Inflow
/
7so.o7ds
_ _
_I I_
_I I�pI {I
Mc ��'I' 1C
■ Outflow
S Primary
It,1111��
`�I
❑ Secondary
850
//
/ /
111 1 1 1
1 1 L L 11
J 1 L L 1
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1 1 1 -peak _Et":.7- gL1W
800
750
//
/
1_1J 1 1_1_11
L LI_IJ
1 L LI_I�+
1�L�II—I_I p�%�I I{ J
1 1J1 1 1
11LL1
1J1LL
I QrWq=l � I, �L
700
650
600
//
1 11 1
1 1 L L 1
11-1-1
1 1 L 1-1-1 -4 L L 1-1-1 L
/
550
1-1 4 1-1-1
4 4 1-1
4 4 1-1-1
4 4 1-1-1 -4 1-1-1-4 4
w 500its
////
/
1 A 1 1 1
1 1 L L 1
1 A 1 L L 1-1-1
1- L 1-1-1 -4 L L 1-1-1 L 4-
" 450
1-1� 4 1-1-1
4 4 1-1�
4+ 1-1-1
4+ 1-1-1 4 1-1-1 4 4
0 400
////
/
/ /
1� 1 111
1 L L III
1 + L 111
1 + L 111 4 + L 111 L +
LL350
/
1-1-1 t 1 1
1fitt1
1_�ttL1-1-1
_t t L 1-1-1 _t t 11 1tt
////
300
1-1-1 t 1-1-1
_tt r I-1-1
_tt r 1-1-1
t t t I-1-1 _tt t I-1-1 t t
////
/
250
I� rt II
rt fi r lI�
rt fi rII
rt t LII rt rt LII rt t
200
/
/
//
1-1 87.45 cfs
— rt r l
1_1_r r- 1
1 I rt_r I— 1 1 1 rt T I— 1 1 I rt t
150
/ /
/
87.45 cfs
100
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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 71
Summary for Pond 105P: Detention Pond Option 1 - Pond 2
Inflow Area = 47.194 ac, 0.00% Impervious, Inflow Depth = 5.06" for 100-year event
Inflow = 269.74 cfs @ 12.12 hrs, Volume= 19.883 of
Outflow = 18.11 cfs @ 13.50 hrs, Volume= 19.879 af, Atten= 93%, Lag= 82.7 min
Primary = 18.11 cfs @ 13.50 hrs, Volume= 19.879 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
Peak Elev= 619.28' @ 13.50 hrs Surf.Area= 3.273 ac Storage= 10.640 of
Plug -Flow detention time= 305.0 min calculated for 19.879 of (100% of inflow)
Center -of -Mass det. time= 304.9 min ( 1,125.1 - 820.2 )
Volume Invert Avail.Storage Storage Description
#1 614.00' 76.150 of Custom Stage Data (Prismatic) Listed below
Elevation Surf.Area Inc.Store Cum.Store
(feet) (acres) (acre-feet) (acre-feet)
614.00 0.000 0.000 0.000
615.00 0.460 0.230 0.230
621.00 4.400 14.580 14.810
626.00 5.880 25.700 40.510
632.00 6.000 35.640 76.150
Device Routing Invert Outlet Devices
#1 Primary 614.00' 18.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 614.00' / 613.50' S= 0.0100 '/' Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
#2 Secondary 625.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 25.00
Width (feet) 50.00 60.00 60.00
Primary OutFlow Max=18.12 cfs @ 13.50 hrs HW=619.28' TW=612.54' (Dynamic Tailwater)
L1=Culvert (Inlet Controls 18.12 cfs @ 10.25 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=614.00' TW=571.28' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 72
Pond 105P: Detention Pond Option 1 - Pond 2
Hydrograph
— T I
fi I
T T I T I rt
/
- + 1-1
-1 4 + + I-
+ �- 1-1
-1 + + +- 1-1-1 4 + I- -I 4
4-
4 1 I - Ip-Ian 1 -4 -1
0119 @C1
LInflow
ry300
dary
/
_ J J 11
-1 1 L L I-
I J J L L 11
i-,�L,r,?rY'h' 3ili•
—
280
,'
1 1 1 1 I I
I I 1 1 1
1 1 1 1 1 1
1 1 P�I�IEIL6V= t9-.2$vI
240
I
I
I I
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�
220
,
/
IIII IIIIIIIIIIIIIIIIIIIIIIIIIIIII
200
i
-I� rt -I-I
rt fi r l-I�
rt fi r-I-I
rt t r 1-I-I rt t r-I-I rt t
w 180
'i
I� 1 1
14 1
1� + 1
1 1-4 + 1 1 1 4+ 1 1 1-4 +
160
/
/
IJ 1 1
1 J 1
1
1 1 1 1-4 L 1 1 1
3
_0 140
�
100
'
80
/
60
,
/
18.11 cfs
40
/
18.11 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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 73
Summary for Pond 106P: North 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 = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min
Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 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= 586.00' Surf.Area= 0 sf Storage= 0 cf
Peak Elev= 609.00' @ 0.00 hrs Surf.Area= 0 sf Storage= 0 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
#1 609.00' 1,184,473 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)
609.00 0 0.0 0 0 0
610.00 75,000 1,140.0 25,000 25,000 103,420
622.00 120,000 1,400.0 1,159,473 1,184,473 158,139
Device Routing Invert Outlet Devices
#1 Primary 609.00' 24.0" Round Culvert
L= 50.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 609.00' / 608.00' S= 0.0200 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf
#2 Secondary 620.00' 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=0.00 cfs @ 0.00 hrs HW=609.00' TW=608.00' (Dynamic Tailwater)
L1=Culvert ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=609.00' TW=608.00' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 74
Pond 106P: North SW Detention Option 3
Hydrograph
Ery
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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 75
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)
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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CI 25yr, 1111 PIMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paoe 76
Pond 107P: East SW Detention Option 3
Hydrograph
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 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 I I
1 1-t+L1 1 1ALLI- -L1L1 1 1 1 I 1
3.12 cfs
3.12 cfs �a �V= Lb 6
3
Storage =3066 Hof
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 I I
i 1 1 14+ 1 1 1-t+t-I- - 4 1 1 T- 1 1 1-t+ 1 1 1
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 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 I I I I I
u+ 2
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 I I I I
3 11 1-f+t-I 1 1-tfiFI- -�f-I 1 1-f 11 1-t+1 —1
o
a
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 I I I I
1 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
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
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)
Ery

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 77
Summary for Pond 108P: RAB Ex. Spillway (no storage)
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 25yr, 100yr, PMP
Closure Plan HydroCAD model 9.19.19 Type 1124-hr 100-year Rainfall=7.39"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 78
Summary for Pond 200: RAB Outlet Pond (no storage)
Inflow Area =
47.194 ac,
0.00% Impervious,
Inflow Depth = 5.05" for 100-year event
Inflow =
18.11 cfs @
13.50 hrs,
Volume=
19.879 of
Outflow =
18.11 cfs @
13.50 hrs,
Volume=
19.879 af, Atten= 0%, Lag= 0.0 min
Primary =
18.11 cfs @
13.50 hrs,
Volume=
19.879 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Tertiary =
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
Peak Elev= 612.54' @ 13.50 hrs
Device Routina 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 '/' 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=18.11 cfs @ 13.50 hrs HW=612.54' TW=565.70' (Dynamic Tailwater)
t-1=RCP Culvert (Passes 18.11 cfs of 217.50 cfs potential flow)
t-2=42" Culvert Steep (Passes 18.11 cfs of 100.09 cfs potential flow)
t-3=42" Culvert Shallow (Passes 18.11 cfs of 60.50 cfs potential flow)
t-4=54" Culvert (Inlet Controls 18.11 cfs @ 4.10 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=571.28' TW=565.70' (Dynamic Tailwater)
5=Emergency Spillway ( Controls 0.00 cfs)
Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=571.28' TW=565.70' (Dynamic Tailwater)
t-6=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 79
1E
1E
17
1E
1E
14
12
N 1e'
11
3 1C
o
LL
Pond 200: RAB Outlet Pond (no storage)
Hydrograph
++ I.
Imo+ I
1-1+ : i i I++�-I—I-i+t-I—I-
1 T T T I
I T T T I
1 1 T T T I 1 T 7 T r 1 1 T T r 1 1
■ Inflow
1 1 1 1
r o 1,941
■ Outflow
■ Primary
1-1
1—
1—III I-7��L --cl —
■ Secondary
+ + 11
+ + 1
11 + + Peak-Bev-54�15 2.4r1
■ Tertiary
71-1-1
T T 1-1-1
T T r 1—17 7 T rl I J T r 1-1—
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-
1 4- 1-1-1
-4+ 1-14 1-1 - 1-1-
1 T 71
1-1-1 _I 1 L I_1_1
I 17 T 71
L 1 L I_IJ
IT T T rl
1 L L 1-1
11 T r I 1
J 1 L 1-1
I I+ ++ 1-1-1-4
+ + I
114 +�- 1-1-�+
1 1
-I—I -1 T 1-1-1
T T r 1—17
rt 7 r 1-1
-1 T r 1-1
111 1
r
t- L 1 11 L_ L 1-1-1-1
1 L 1
11 1 L L 1
1 J 1 L 1 1
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)

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 80
Summary for Link 102L: Lake Wylie/Catawba River
Inflow Area = 215.660 ac, 0.00% Impervious, Inflow Depth = 4.55" for 100-year event
Inflow = 74.36 cfs @ 13.65 hrs, Volume= 81.682 of
Primary = 74.36 cfs @ 13.65 hrs, Volume= 81.682 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
. III
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 I I I I
80
7a.36 cfs I I I 1 I
�I �1
7a.3s cfs �Iow rea=2-.660 gc
75
�
1/� II �
70
65
60
1 1 L L I 11 1 I L 1 1 1 L L L I I 11 1 I J J 1 1
55
50
v 45
c 40
— — — — — — — — — — — — — — — — — — — — — — — — —
— — — — — — — — — — — — — — — — — — — — — — — — — — —
LL 35
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
30
1-1— 1___ 7—1-1-1-17 -t-T 7 T 7 r 1-1-1-1-1-1 7 7 rt T
/
—1-1— 1 1-1-1-1 rt rt t t fir I—I—I-1-1-1 rt t
25
I I I I- 11 1 1 -4 4 4 L 1 1 1 1 1 1 4 4
20
15
1-1 1 1 L L 1 1-1-1 1 1 L L L I I 11 1 1 L L 1 1
10
I I I I I I I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
5
i i i i i i i i i i XIIIIIIIIIIIIIIIII MI
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

Closure Plan HydroCAD model 9.19.19
Prepared by AECOM
Allen CbE 25yr, 100yr, PMP
Type 1124-hr 100-year Rainfall=7.39"
Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 © 2015 HvdroCAD Software Solutions LLC Paae 81
Summary for Link 104L: Lake Wylie/Catawba River
Inflow Area = 294.538 ac, 0.00% Impervious, Inflow Depth = 4.30" for 100-year event
Inflow = 105.54 cfs @ 13.71 hrs, Volume= 105.600 of
Primary = 105.54 cfs @ 13.71 hrs, Volume= 105.600 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
I I J 1 L L L L I
1,, 1 L L L L r I 11
1 L L 1 1 L L r I
i
I— I—11! 4 T 4- 1- 1—
1-1-1 —1 4 4 T k- I— I
—I —1 —1 -4 4 T 4 k I—
■ Inflow
115
— 1oss4cfs rt-r fi r I
I I I I rt-t rt fi��y�r* I I
I —I �-1-1 rt fi �/�r-1
Primary
110
,
— — 105.54 cfs T
—
Area �4-5Wa
105
T
— — - — — — —
1-1-1-1 1InfoYY
— — — — — — — — — — —
I-
— — — — — — — — — —
100
i
I I 1 LLI
1 1 1 ILA-1LLLL1 1
1 ILLIILLLI
95
i
— —I—I I—
1-1-1 —1 + -4 -+ + + {— 1-1-1-1
+ + -+ + + + 1-
90
—I—I-1 TI-1-1-1—IT77TT-FF1—I—I-1TTTTTTTI-
85
80
i 1
1 1 1 1
— — — — —
1 1 1 1 1 1 1 1 1 1 1 1 1
— — — — — — — — — — —
1 1 1 1 1 1 1 1 1 1
— — — — — — — — — —
75
1 1 1 -4
1--1-tj 1 1
1 1--t1I
70
1 1— 1t
1- tfifit- i—1 1
1 I-1fitfitl
—I—I T T -1
1-1-1-1 T T T T T T T
1 T T T T T T T I—
60
55
_6
LL 50
i
—I—I
—1-1-1 -4 4 T k- 1-1-1-1
-4 4 T 4 k-
45
II— rtrtrtfiI�rtrtrfirr111Ir-1rtrtfir-r.—
40
1 1 1 1 1
I I I I I I I
35
i
— — — — — —
— — — — — — — — — —
— — — — — — — — — —
30
i
II_ 1 1 L L_
I L A 1 L L L r III1
L L 1 1 L L r 1
25
i
—I—I 4+ 4- 1-
1-1 -4 4 T k- 1-1-1-1
-4 4 T 4 k- I-
20
IF TTL-
1T1JTTl—F1 1
1 1TTrtTTTFI
15
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)

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 82
Summary for Subcatchment 102S: DA 102
Runoff = 1,266.31 cfs @ 2.85 hrs, Volume= 94.914 af, Depth=21.56"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Area (sf) CN Description
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 fps
10.2 850 Total
Subcatchment 102S: DA 102
Hydrograph
1,400
_I _I _I _I I_I_I_I_I_I_I_I _I_I_I_I_I_I
■Runoff
1,300 1,266.31
cfs
9-U S"
1,200
� -�6Iht-Allan PMP- Synthetic
1,100
1 AWA RMIP �Synthl Rlainfallt25.707
1,000 I
1 1 1 1 1 1 1 1 RulndfflAteti-2,301,379 sf
- I I -I-II rt rt t-r r I I rt 1 Aurlc�ff1V616rneA 4.014 of
at -
goo
goo
JI
1 1- 1 tU6CIff
t� gly,
m
v
1 1 1 1 1 1 1 l�l ' m1
1 1 1 I I I I 1 1 II�W 4� I�It��'-'
700
o
-' I I -1 -f t + i- I I II I I I -1 -f -f + t t- }-c7-1"1Pln
500
1 1 1 1
T 1 T T 1 1 1 T T I 1 1
400
IIII II
300
1 1 l 1 1 1 1 1 1 l 1 1 1 1
200
—1—IT�rt7TTT.r1-1-1-1-1-1—I-irtrtTT7 1-1-1-1-1-1—I
100
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 83
Summary for Subcatchment 103S: DA 103
Eastern Face of Mound
Runoff = 779.07 cfs @ 2.85 hrs, Volume= 60.341 af, Depth=22.93"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Area (sf) CN Description
1,375,819 80 Final Cover
1,375,819 100.00% Pervious Area
Tc Length
(min) (feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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
_1JJ 11LLLLLI_i_i_i_1_1_i_iJJJJ11LLL
850
800
779.07
ds
750u{stQnl
1 1 1 1 1 6-hr Allen PMP I- $ynthetic
700
650
1 1 1 1 1 T T 1 AhI1�A PMP -SVnih 1Riihfill1 25.101'
600
- 1-1-1-1-1-1 rt rt rt rt r r r l- 1— 1— 1-1R1-10 f�►r a 1 3*7�81�sf
�f�l+
-t -t -t + t t 1- t- — — — — -I-I - -9 t t-
550
— I— — —1 —1 —1 -4 -4 4 T T I— I— I— I— IR4goflf_Volume=6q.34ta1f
H 500
_ - 1-1-I -I -I I- 1— 1— 1- - -1 Rt noff Depth=22.931'
450
1 -14©w LengthL1,2bC�
c 400
a
Fq.
err
350
rtC_�l
=
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 I ICN 8OF
300
250
—1-1-1-1-1-1-1-trtr7Trrrrr1-1-1—I—I-1-1-1rr7TTTTr
150
— + + i- — I— I— I-1-1-1 —1 -+ -+ + + + t i-
100
—1-1-1-1-1 -4-4 4 4 T 4- 4- I-1-1-1-1-1-1-1-4 4 T T T 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)
❑ Runoff

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 84
Summary for Subcatchment 104S: Area Draining to 104
Runoff = 680.79 cfs @ 2.88 hrs, Volume= 53.699 af, Depth=22.93"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
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
-4 -4 4 4 4- 4- 1- I-1-1-I-I-I-1-1 4 + 4- 4
750
j-I-1-1-1-1-1-1
i I
I I I I III I I I I I I I I I I II I I I III I I I I
700
s80.79 cfs
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 p 1. , 1f 1
tpnT
--1 -t t t t t L L 1 1 1-$-hr-AHen PMPt Synthetic
600
1-
1- 1-1-1 -1 -1 --4 --1-L -L 1- !- !- I�WA=s�ni�irR�Irif2lll125.1<0
550
I_
I_I_I_I I I I I I I I I I I I I I_ I_ I_ I_I I I I I I I I I
R�tr�01� i r��#,�2 ,36 1
500
-1-
1-1-1-1-1 -T-f 7 T T T T T T T I- I- IRpnoflf-Vol --153.60$alf
w 450
-
I- - -I -I -I -f -i t -� i I- I- I- I- --IRttnoff-Depth=22.9,311
3400
J LLLLLLL I I I I 1 1-14WLe OhL-fGW
c 350
U.
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 '� I I. I
-71�'+�1��
300
1 1 1 1
1-1-1-1 1 1-1-1-1 7 t T T L L L 11 1-1-1-1 1-1-1-T 7 rt IGM404
250
1 111 1 1 --4 --4 4 t -k L L I I I I 1 1 -1 --1 --4 --4 4� L L
200
150
100
-I-
-1-1 -1 -1 -1-t-t t t t t t t t I- I- 1- 1-1-1-1 -1-1 t t t t t t t 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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 85
Summary for Subcatchment 105Sa: Area draining to 105
Runoff = 513.19 cfs @ 2.88 hrs, Volume= 40.558 af, Depth=22.93"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Area (sf) CN Description
924,750 80 Final Cover
924,750 100.00% Pervious Area
Tc
min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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 105Sa: Area draining to 105
Hydrograph
550
500
513.19
cfs ______ J J J 1 1 L L L L L_ I_ I_ I_1_1 _1 _I J J J J 1 1L L 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 PWOM
❑Runoff
1 1 1 1 1 1 ++ 1 1 1 -6-hr-AHen PMPi- Synthetic
450
AWA PMP-!Slnfh 136i6fdI1i25.70"
400
�
I IIIIII I I I I I I I I I I I IIIOuu1np1 fidrla-9�4715�Sf
RO-noff Volu-'n1q-40.515$ a1f
350
N
- 1— 1-1-1 -1 -1 -4 -4 + + + + + + + 1- 1- 1-1-1-1 —1 Runoff Depth=22.931'
300
o
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Flow Lehgth-l' 050'
——I—I—I —I —I 7 T T T T L— —I —I —I —I
250
�c"—T1�4. rr�r�in
1 7 1 1
'
1 IC����
200
I I 1 1 1 1�-4-4 4 4+-kt- I I 11 1 1 —1 --1 -4-4 4���
150
I I 1 1 1 1-1-1 1 rt 7+-r r r F I I 11 1 1 1-1-1-1 7 1-r T- T- r
100 ]
I 1 -1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HydroCAD®10.00-14 s/n 01723 ©2015 HydroCAD Software Solutions LLC Paae 86
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 = 1,706.38 cfs @ 3.09 hrs, Volume= 145.900 af, Depth=21.37"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 87
Subcatchment 106S: DA 106
Hydrograph
1,900
— — 1-1-1 —1 t rt t t t t 1— I— 1— 1-1-1 —1 —1 rt t t t t fir I— I— I — I —1 —1 —1
■Runoff
1,800
—1 —1 —1 t � t t t t 1- I— 1— 1-1-1 —1 —1 t t t t t I— I— I—��I++—��11 —1 —I
1,70038crs
1,700
1-1-1 1+-1t++++I 1 1-1-1 1 1-1tt++�f I I I Y'1stpm
1,600
1-1 —1 —1 t -t t t t t 1- r 1— 1— 1-1 —1 —1 —1 -t -t",-Aflan PMP— Synthetic
1,500
1-1-1 —1 � -t t t + 1- 1- I— 1— 1-1 —1 -AWA PMIP+Sgntht-RlaInfaHt25.7V
1,40o
1 1 1 1+ +++ 1 1 1 1 1 1 1 fRundWAte.6 i,5f"02-7 tf
1,300
I
I + + + I I-Run+offVoruril6-14$.90i4 alf
1,200
-1-1-1-1 + -44++ ++1-1-1-1-1-1-1-444+ f 1- �3
1 F�ur�icrff D�p�Ti_21.7"
in 1,100
1-1-1-1+-44+++��I—-1-1-1-1-1-444 4- 1-1-1- 1—,
1,000
1 1 1 1+-44++++ 11 1 1 1 1 1-A44++Fo1�U eqt�=1�3
900
1 - 1-1 —1 —1 + -4 4 + + + 1— 1— 1-1 —1 —1 —1 -4 4 4 + + 1— cF2�.2 in
_0
a 800
-1-1-1-1 -4 4 + 4- i- I— 1— 1-1 —1 —1 —1 -4 4 4 4- 4- 1-1-1—IJ�N-FZ1
700
1 1 1 1 -444+ t 11 1 1 1 1 1-444+fit 11 1-1-1 1
600
I
1 1 1 1 A44+t-t 11 1 1 1 1 1-444+fit 11 1-1-1 1
500
I
-1-1-1-1� 4 t 1-1-1-1-1-1-1 � 4 4 1-1-1-1-1-1—I
400
1-1-1 1 A44+t-t 11 1 1 1 1 1-444+fit 11 1-1-1 1
3001
1-1-1-14 4 t 1-1-1-1-1-1-1 � 1-1-1-1—I-1-1
200
—1 —1 4 4 t 1— 1— 1-1-1 —1 —1 --4 1— 1— 1-1-1 —1 —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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 88
Summary for Subcatchment 107Sa: Northwest AAB
Runoff = 937.42 cfs @ 2.89 hrs, Volume= 72.901 af, Depth=21.56"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Area (sf) CN Description
456,118 80 Final Cover
537,538 61 >75% Grass cover, Good, HSG B
773,974 75 Residential
1,767,630 72 Weighted Average
1,767,630 100.00% 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 fps
14.1 1,050 Total
Subcatchment 107Sa: Northwest AAB
Hydrograph
I I I I I I i i i l l i i i i I I I I I I I
I
■Runoff
1,000
1 1 1 pustom
900
_I_I_I_I_I _I_I_I_I_I_I
1-1-1 �y— yntheti�
s5o
-1 -1 —1 —1 — -1 —1 —1 — —PAR=
-
800
1_1 _1 _I 1 -i 1 1 1 L L � I_ I_ I_I _I _A EMP�Syrdhl�lainfallt25.7QI'
750
L-1 1 1 L L L L I 1 11 1 1 1-1 1 Ruln6ffiAJea_-1,767,630 sf
700
-I-I -I - 4- - -I-I -I -I Auh6ffV616r e? 7"01 of
650
1-1-1 -1 4 4 4 k- I-1-1-1-1-1 -1 4 4 T' Fuiciff DepFihhFn66
550
(�"
- -I -I -I + fi t + + tF��1eiT�-tit—�
0 500
LL 450
-1-1-1-17 -1 7 T T T r F I-1-1-1-1-1-1 -T T TT T T r- 1-1-1-1CI77L
400
I I I I I I I I I I I I I I I I
350
300
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
250
200
IIIII IIIIII IIIIII
150
I_I_I_I
100
_I _I 1 -t 1 1 1 L L L I_ 1_ 1_1_1 _1 _I -1 1 1 1 L L L 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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 89
Summary for Subcatchment 107Sb: NW of North face of AAB
Runoff = 285.08 cfs @ 2.88 hrs, Volume= 22.530 af, Depth=22.93"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Area (sf) CN Description
513,700 80 Final Cover
513,700 100.00% Pervious Area
Tc
min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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
300
280
285.08
-t -t t t t t t t- I— I— I— I— I —1 —1 —1 t t t t t-
cfs
C►WOM
❑Runoff
260
1 1 1 1 1 1 1 1 1 1 1 6-hr Allen PMP 1- Synthetic
240
1 1 1 1 1 1 1 1 AWA PMP-rSlnfh 136irifal11i25.70"
z2o
—1-1-1-1-1 -1-T-f 7 7 T T T 7 7 I— 1-1-1-1— b—I npf �►r7 7 7
a7-5170sf
F'
200
1 1 1 1 1 1 L L L L L L 1_ 1 1 1 IRpnoflfyolurne =2Z.5L3af
y 180
— —I—I—I —I —I —I 1 1 — — — — ——IRUnoff --�Ih�2Q.—
3 160
IF16W Lerhgth61,050'
o
140
'
I
�C-1�4.
,L
in
1 1-1-1 1 1-1 1 1 1 1 t t- L r- r- 11 1 1 1 1 I� rt rt 7-r�
120
�Q
—1-1-1-1-1-1-4-4-4444-4-� I-1-1-1-1-1-1-1� 4-Cv:;8p
100
80
60
1-1-1-T 7 7 T T 7 7 7 1 1 1-1 7 7 7 T T T T 7
40
IIIII1-1 -177++LIIIIIIII++���
20
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 I I 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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 90
Summary for Subcatchment 108S: Area draining to 102
Runoff = 530.86 cfs @ 2.84 hrs, Volume= 40.550 af, Depth=22.93"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
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 fps
9.7 750 Total, Increased to minimum Tc = 10.0 min
550
500
450
400
350
U
3 300
_o
U. 250
200
150
100
50
Subcatchment 108S: Area draining to 102
Hydrograph
___ I_I_1_1 _1 _I J J J 1 1 I L L J L_ I_ I_ I_ I_I_I_I _I J J J J I I L L L
8s cfsl 1 1 1 1 1 1 1 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
177IIrrL I I I --1-17—Gustol7i
_ 1_ 1 1 6-hr Allen PMP - Synthetic
1 1 1 1 1 1 1 1 AWA PMP -Synth 1Rainfall-25.70"
un ff 4►r a-92 5y1�s'f
1 1 J J 7 T T r r T- T- 1 1 1 1 IRunoff -Vol uMP--4Q,5Wa1f
I I I II i-I I 1 1 Runoff D eptIh=M.931,
I I 1 1 1 I I P16W L66gthL750'
I I 1 1 1 —1 --1 -4+++++++ I I I I 1 1 1++
c71-IG t+I�n
1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 1 1 1 40r
I I I 1 1 1 I I I I L L I I I I I I I 11 L L L I I I 11
------I -t -t -t-ttti- t- t- 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 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 I I I I I I I I I I I I I I 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)
❑ Runoff

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 91
Summary for Subcatchment 201 S: DA 201
Area that drains using HydroCAD catchmentarea +38.75 acres to the southwest of the basin by the pond
Runoff = 2,203.17 cfs @ 3.16 hrs, Volume= 194.191 af, Depth=21.37"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Area (sf) CN Description
1,200,000 60 Woods
1,310,000 75 Residential
2,239,000 74 >75% Grass cover, Good, HSG C
4,749,000 71 Weighted Average
4,749,000 100.00% 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
Subcatchment 201 S: DA 201
Hydrograph
_ _1_1_1 _I J_t 1 1 1 L L L I_I_1_1_1_1 _I -1 1 1 1 L L L I_ I_I_1_1_1 _I
2,400
1 1 1 1 1 1�-4 4 4 T t- k I 1 1-1-1 1 —1 -A 4 4T I I I
■Runoff
2,300
cfs rt rt rt t T fi r l rt rt rt rt T i r l
2,203.17
2,200
F F 1 1 17 7 7 T 1 1
2,100
2,100
_I _1 _I J t 1 1 1 L L L I_ 1_ 1_1 _1 _1 _I -1 16lhrr-ADeLn PM—P t5-yn-th_efF
1,900
1-1-1 —1 -1 -+ + + + + 1— 1-1-1 —1 —AWA PMP+SyntWRlallnfell�_-25r.7al'
1,800
I
11 I -1-1T T T T T F F F 1 1 1 1 —1-1T FRuTn6 frAre6-�749�00 sf
1,600
I
- I _ I —1 —1 —1 I I I I I I I_ 1— 1— I _ I —1 _1 _I I �nbf'l Vo�rk�=194.119-� aif
1,500
1 I I I 1-1 A j j T T L I I I I 1 1 1-'-'-' T kulnvrf1Depih� [7 �7"
c; 1,400
1,300
— --
1-1-1-1-1-1_t1-t+1-1- I-1-1-1-1-1-1_tfi1-+t t1 _I — I I —I —I
T11Pw-"n9Ith0-'
I
1 T T T T 1 1 1 1 1 T T
c 1,200
CF-2-2 i �m
LL 1,100
1,000
-1-1-1-1 -4 4 4 � 4 1-1-1-1-1-1-1 -4 4 4 1-1-1-1�INFZ1
900
firl—I—I-1-1—I—I
800
-——I—I—I 1 1————I—I—I T I ———177
700
600
1_1_1 _1 J_t 1 1 1 L L L I_1_1_1_1_1 _1 -1 1 1 1 L L L I_ 1_1_1_1_1 _I
500
1-1 —1 —1 -4 4 4++- I— 1— 1-1 —1 —1 —1 -4 4 4+ 4- 1-1-1-1-1-1 —I
400
M ITrtrtrttTl-rl 1 1 1 1 1 IrtrtrtrtTfirl 1 1-1-1 1 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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paoe 92
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 = 992.25 cfs @ 3.07 hrs, Volume= 84.132 af, Depth=20.61"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Area (sf) CN Description
1,020,000
60 Woods, Fair, HSG B
1,114,000
74 >75% Grass cover, Good, HSG C
2,134,000
67 Weighted Average
2,134,000
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"
2.4
100
0.0200
0.71
Shallow Concentrated Flow, shallow
Woodland Kv= 5.0 fps
0.8
100
0.1600
2.00
Shallow Concentrated Flow, shallow
Woodland Kv= 5.0 fps
24.0 300 Total
Subcatchment 202S: DA 202
Hydrograph
— — —I
—1 —1 --f -t T t t 1- f- I— 1— 1-1 —1
—1 —1 -t -t t t t- f- I— I— I-1-1 —1 —1
1,100
———I—I—IrrtrtrrrrrI—I—I-1—I—I—I-rtrtrrrrI—I—I—I—I—I—I
1,050
99225cfs —
I
I
1,000
1 1 1 1 1 1 1
��I++
1 1 I I I I 1 1 Y-4stIOT9
950
1_1
1 1 1 1 1 1 1_ 1_ 1_ 1_1
1 161 r A-nen PK - Synth -eft
900
_1 _I _I _1
_1 _I
850
_ 1-1
—1 —1 --1-t1 1 1 L L L I— 1— 1-1 —1
-AWA PMP�SynthLRlainfall=25.701'
800
1 -1-1
—1 —1 -4 4 4 1— 1— 1-1 —1
—1 —1 -4 4 fRUn6ffAie6=2,134,000 sf
750
—1
—1 —1 t t t t t 1 1— 1-1-1 —1
—1 —1 --t -t F%u+n6ff1V &iiilie184.132 61
700
11111
� rt rt rt t r r r 111111
�. rt .. t 1 � �
143u]6&f Depih=20-61
m
650' t 600
I
— — — — — —
— — flgw 4ength= 0�'
550
°
I
I I I
I—
TCfi�f�0 rrfl-n
500
LL 450
1 1
1 1 1�-1-t j t I I 11
1 I I -A -t -t t I I I I CN:F617
400
I 1 1
1 1 1 -4444 t- k- I 1 1 1
1 1 1-4444-�1-k-I 1 1-1-1 1 1
350
i
1 1t-1-tttFf I I I 1
1 1 1--1-f-ftti-f I I I 1 1 1 1
300
1 1T-1rtJTTrFl 1
1 I-1rtrtTTrrl 1 1 1
250
i
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
200
150
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 I I I I I I
inn
IIIIIIII
IIIIII
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paoe 93
Summary for Subcatchment 203S: DA 203
Runoff = 879.89 cfs @ 2.89 hrs, Volume= 69.095 af, Depth=22.43"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Area (sf) CN Description
920,000 74 >75% Grass cover, Good, HSG C
690,000 80 Final Cover
1,610,000 77 Weighted Average
1,610,000 100.00% Pervious Area
Tc
(min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(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 fps
14.2 700 Total
Subcatchment 203S: DA 203
Hydrograph
950'
IIIIIIi i I l i l i 1 1 IiiiIIiI I I I I I I I
__I— — — — I —I — I 1 1—————— — I —I —I
900
87s.8scts
1 1
I_ I_ I I I 14`u$tQro
850
_ _ _I _I _I _I _
800
1 1 1 1 1 1 1 1 1 1 1 6-hr Allen PMP 1- Synthetic
750
1llil�f�i112�.(0t,
f =t, I 1101 Si
650
I_ I_1_1-1 —1 —1 —1 1 1 1 1 1 1 J J I_ I_ 1IRII
a1f
600
_ I_ _ _I _I _I _I 1 1 1 1 1 1 1 1 1 — I— I— I-1RgnofiIfYojUrnq=16%.01951
550
' ,
1 Runoff Depth;Q,43"
" 5001,
I_ 1_ 1 _ 1 _1 —1 —1 _I J 1 J J I I I J J I— 1_ I— I— I _ 1 —1 —1 -Fi6w Ner4gthL7-00'
_0450
IIIIIII IIIIIIIII '�.I .I
400
11-11-1-1-1 J J J J J I I I J J I_ 1_I—I-1-1-1-1_I J J 1 711"
350-'
111LLLL1 11 1 1 1 1 IJJJJIICM=�7
300
1— 1 — 1 —1 —1 —1 J J J J J J L L J L I— I—I—I—I-1-1—IJ J J J 1 1 L L 1
250
I I I I 1 —1 -1 J J 1 1 L L L L J I I I 1 1 1 IJJ J J 1 1 L L L
200
_-1-1-1—IJJJ111LLLLI—I—I—I-1-1-1-1JJJJ11LJ1
150
1 1 I 1 1 1 -1 -1 -1 1 1 L L L L L I I I 11 1 1 1-1 J J-1 1 I L L L
1 oo
I I 1 1 I J J -1 -1 1 1 L L L L L I I I I J J J J J-t 1 L L L
50
'
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 94
Summary for Subcatchment 204S: DA 204
Runoff = 592.54 cfs @ 2.97 hrs, Volume= 49.604 af, Depth=22.93"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Area (sf) CN Description
1,131,000 80 Final Cover
1,131,000 100.00% Pervious Area
Tc
(min)
Length
(feet)
Slope Velocity Capacity Description
(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,
Short Grass Pasture Kv= 7.0 fps
7.3
1,500
0.0067 3.40 108.91 Trap/Vee/Rect Channel Flow, Channel south of landfill
Bot.W=10.00' D=2.00' Z= 3.0 '/' Top.W=22.00'
n= 0.045
20.1
1,950
Total
Subcatchment 204S: DA 204
Hydrograph
650
❑Runoff
600
592.54 cfs
�+
550
1 6-hr Allen PMP I- Synthetic
500
1 1 1 1 1 1 1 1 1 1 1 1 1 AWA PMP -SVnih 1Rilhfiii1 25.100'
450
1 1�-A-t+++++++I 11 1-1-1 n1 +-4 +
1_ 1 1 1 1 1 1 1 1_ 1_ 1 R�l_To�f rea�11,11311,010�Sf
_
_ _1 _1 _1 _1
I RWnoflfNo I u-Mq=-4� 6104FaI
400
—1 —1 -1 -t -t t t t t 1- t t I— I— I— I— I — I —I Runoff Deptlh:i22.9- '
350
1 -1 b16W Length-1,95
300
C2J.n.
Tin
-I -1 11 1 1 1 tt7I
I I I
250
ICM40
200
—1-1-1 —1 —1 -1-T-f T T T T T T T I— 1— 1— 1-1-1-1 —1-1 T T T T T T T T
150
100
im
50
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 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 I I I I I I 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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 95
Summary for Reach 102R: Ditch 102
Inflow Area = 155.968 ac, 0.00% Impervious, Inflow Depth = 21.65" for AWA PMP -Synth event
Inflow = 3,239.77 cfs @ 3.07 hrs, Volume= 281.365 of
Outflow = 3,223.99 cfs @ 3.11 hrs, Volume= 281.365 af, Atten= 0%, Lag= 2.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 11.11 fps, Min. Travel Time= 3.6 min
Avg. Velocity = 1.89 fps, Avg. Travel Time= 21.2 min
Peak Storage= 696,187 cf @ 3.11 hrs
Average Depth at Peak Storage= 6.16'
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 '/'
Inlet Invert= 608.00', Outlet Invert= 595.00'
Reach 102R: Ditch 102
Hydrograph
1
1 1 _t t fi t 11
1 1 fi+ t- t__�I 11 1 fi t t 11 1 1-1 _t
III
fi tIII
+ t �IIII + tIII
3,600 3,239.77
cfs
I —I � � + t i- � I
—I —I —I � � + ��M��I—^I`—�I,—I��p � +
3,400 3,223.99
cfs
+ +
i����I—�I—(�IQ
4 + ifi FI IO Y1I A � 4 55 a 6VI ae
3,200
3,000
1
1 1 -t+ I
I 1 1 4 + "A�' /F I CII � #1h � I
r—I
1-1
—1 - 4 k- I-1-1
—1 -4 4 + k T ' I T— Ir�� l� it
2,800
1-1
—1 - 4- 1-1-1
—1 4 I— �i� ve�_11 :'1 1- fPS
2,600
1
1 1 4 4 1
1 1 1 4+ 1-1-1 1-4 4 4 �- I 1 1
2,400
n C4
I _t1
I 4- �n-_0_025
2,200
2,000
J J-1 _L L L L I-1-1-1
L 1 1 L L L1-1-1-1 L L 1 17-1—. , U
3 1,800 i
—1JALLLLI
1 1 IL1+LLL1 1 1-1 J J1.0._005 Jr/s
i° 1,600
J J J J L L 1
1 1 1 J 1+ L L J J„� f� l—I J
1,400
_I J J J J L J I_
6-1-1-1
1-1 —1 J 1 1 L LC�pC1�� XL=1 L_ KOSJ
1,200
I J 1 I—L1-1-1J11LL1-1-1-1-1J
J I I LL1-1-1 1 1
1,000
800
600
400
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 96
Summary for Reach 104: Ditch 104
Inflow Area = 28.108 ac, 0.00% Impervious, Inflow Depth = 22.93" for AWA PMP -Synth event
Inflow = 680.79 cfs @ 2.88 hrs, Volume= 53.699 of
Outflow = 672.61 cfs @ 2.92 hrs, Volume= 53.699 af, Atten= 1 %, Lag= 2.1 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 6.82 fps, Min. Travel Time= 3.8 min
Avg. Velocity = 1.38 fps, Avg. Travel Time= 18.8 min
Peak Storage= 152,954 cf @ 2.92 hrs
Average Depth at Peak Storage= 2.13'
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 '/'
Inlet Invert= 588.00', Outlet Invert= 579.00'
Reach 104: Ditch 104
Hydrograph
I- 1-1 -1 -I -4 7 + + 1- + I- 1- 1-1 -I + 7 7 + + 1- I- I-I-1 -I + + + + +
I
I I I I I I I I I I I I I I I I I I I I
750
-I -I -I -I -I -I -I -I -I -I -I -I -I -I
680.79 cfs I I I
700
cfs 1 I I 1 1 111 1 I I 1 Inflow Area=28.IllWaC
672.61
650
A � �jow �
600
-1-1-1 � 7 + + t- 7 7 =I� � •N
550
%
-1 7 1 L L L L 11 1 -1-17 7 1 L L X( _I of 0_0� T �'I _I
T
500
450
400
I I rt rt rt L r I I I rt rt rt rt L r I- I- I I Lam ,-550.0'r-
3
0 350
' ' I -I + 7 + + + + I- I-1-1 -I + 7 7 + + + + I- I-I-1S1 -64 , I--
a_I
1 L 1III 1 L 1III a I
300
I.n�
250�
T1 9n�� *1
200
I-17TTrLI 1777TTTL1 1777T7-
150
I I 7ttt- I 1-1-1 I 77ttt- I I 1 1 I-d7_++f---
I -I J 7 1 L L L I- I-1-1 -I L L L L L L L I_ I I 1 7 1 _I I
100
1 1 1 1 1 1 1 1 1 1 1 1 1 1, I I I I I I I I I I I 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)
■ Inflow
❑ Outflow

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paoe 97
Summary for Reach 105: Ditch 105
Inflow Area = 21.229 ac, 0.00% Impervious, Inflow Depth = 22.93" for AWA PMP -Synth event
Inflow = 513.19 cfs @ 2.88 hrs, Volume= 40.558 of
Outflow = 507.59 cfs @ 2.92 hrs, Volume= 40.558 af, Atten= 1 %, Lag= 2.5 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 9.09 fps, Min. Travel Time= 3.6 min
Avg. Velocity = 2.10 fps, Avg. Travel Time= 15.8 min
Peak Storage= 111,087 cf @ 2.92 hrs
Average Depth at Peak Storage= 1.60'
Bank -Full Depth= 4.00' Flow Area= 168.0 sf, Capacity= 2,571.90 cfs
30.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 54.00'
Length= 1,990.0' Slope= 0.0151 '/'
Inlet Invert= 618.00', Outlet Invert= 588.00'
Reach 105: Ditch 105
Hydrograph
550
�
I I I I
513.19cfs _I
I I I I I I I I I
-I -I L L L L L L I-
I I I I I I I I I I I I I I
I-1-1 -1 L L L L L L L I- I-I-1
1 1
I I I I I I I I I
-I L
LL L L L L
cfs .
Inflow Area=211.2291
eL� e
as
so7.5s
500
-1
-1 1-1rtTTTFI
1 1 1 1T-1rtdTT II 1
AVI9h P�QW
1pp-1}�-FjT. V
�Yp`lh;=_
450
_ I
_I _I
_ I_ I _I _I 1 I
•Iv'_ I_
I�
400
-1
-1 1�4 t 1
1-1-1 1 -t4+- t7-14
1 � f0l� _
11 1 1 I 1 1 1
I 1 1 1 11 11 I 1 1 1 I 1
1 1 I h=A Q251-
350
I I 1 1
I I 1 1 I
300
II
1 1 1 1 1II
1 1 1 1 1 1 1111
L=_1 799Q.0'1
c
LL 250
—I rtrtfi1 rI----I
rtrtrtfi1 rI---I�I
W W
200
-
I I I I I I I I
--IIIIIT�T�IttllT7`T'�
I I I I I I I �.��+I• �I
� I
�1
150
—I —--I—I
—--I—I
—I
100
__
—-1
1-1rtTTTF
1 —1 -1 rtTTT—I 1
—1T_tJTT——
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 98
Summary for Reach 106R: Ditch 106
Inflow Area = 81.911 ac, 0.00% Impervious, Inflow Depth = 21.37" for AWA PMP -Synth event
Inflow = 1,706.38 cfs @ 3.09 hrs, Volume= 145.900 of
Outflow = 1,703.88 cfs @ 3.10 hrs, Volume= 145.900 af, Atten= 0%, Lag= 1.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 9.17 fps, Min. Travel Time= 2.2 min
Avg. Velocity = 2.07 fps, Avg. Travel Time= 9.8 min
Peak Storage= 224,915 cf @ 3.10 hrs
Average Depth at Peak Storage= 4.33'
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 '/' Top Width= 57.00'
Length= 1,210.0' Slope= 0.0050 '/'
Inlet Invert= 614.00', Outlet Invert= 608.00'
Reach 106R: Ditch 106
Hydrograph
10
IrtT II
III�I
190 1,703.88cfs
II
1I 7�
-1t 7� rr rr
I � � T T r � 1-1-1
1I 7� 1I 7rt Trt II -�1 -1T
r�TT 1I
7fir�
-T1 TT
r
I � 1 T T rrrf'WVAiea=fHI. 11I ae
1,700
1,00
-1Tr
7r/1
Avg# 10 —*
1,500
1
1 1 1 1 1 1 1 1
1 1 1 1 1 I 11 1I-I1
1,00
�I T
_-
'T� 1 'f�
1,300
1,200
1
1 1
1 1 1 1 1 1 1
- - - - - - -
1 1 1 T 111 11
1 1 1 1 1 1 1 1 1 1 1 1 1 6-41.02,51
- - - - - - - - - - - - - - -
w 1,100
1 1 1 1
1 1 1 1 1
1 1 1 1 F 1
1 1 1 1 1 1 1 1 1 1 1 1
1,000
$oo
—11-11-11-11—�
—--11-11—� �S�.e,� `iEl
LL
700
-
-I -I aIC)
600
1 T����'f'��
500
1 1 1 1 1 1 1 1 1 1 1 1 1
400
300
qnn
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 99
Summary for Reach 107R: Ditch 107
Inflow Area = 52.372 ac, 0.00% Impervious, Inflow Depth = 21.87" for AWA PMP -Synth event
Inflow = 1,222.32 cfs @ 2.89 hrs, Volume= 95.431 of
Outflow = 1,219.50 cfs @ 2.90 hrs, Volume= 95.431 af, Atten= 0%, Lag= 0.9 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 14.82 fps, Min. Travel Time= 1.6 min
Avg. Velocity = 3.96 fps, Avg. Travel Time= 5.9 min
Peak Storage= 115,170 cf @ 2.90 hrs
Average Depth at Peak Storage= 2.24'
Bank -Full Depth= 4.00' Flow Area= 168.0 sf, Capacity= 3,451.02 cfs
30.00' x 4.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 54.00'
Length= 1,400.0' Slope= 0.0271 '/'
Inlet Invert= 628.00', Outlet Invert= 590.00'
Reach 107R: Ditch 107
Hydrograph
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 I I I I I I I
I 7 T F I
1,222.32 cfs + T ++ 1+ 4+++�I I I 1+++ � +I I I —I --1 T
1,300 9.50 cfs Inflow Area=52L3721 as
1,21
1,200 1 11 1 II I h I
11100 1-1 —I T T T T T T 1-1-1 —1 T T T T M," �Pt�W' e-- r
1,000 I I I �I 1 1 1 1 1 I I 1 1 1 1 1 1 1 1 1 qlki -I017"--Pj0-1
900 I I I I I I I I I III I I I I I I III I I I I I I I n=�01.0251
800--I�rtrtfit rI---I�rttfirrl---Irtrtti rI--I—I�rt
700 —I —I __1 _L L L L L I— I —1 —1 L 1 L L L L I— I —I —1 L L L L=1,400,T
al
400 11 I I 1 1 I I 1 1 I 1 1 I I 1 1 I I 1 I I 1 1 I I 1 1 I 1 1
300 I I 1 I I 1 1 I I 1 1 I 1 1 I I 1 1 I I I I I 1 1 I I 1 1 I 1 I
200 —1 —1 + T + + II1 1 + 4 + — —I—I — + + — L I11I --1 T
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 11 1 1 1 1 1 1 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)
■ Inflow
■ Outflow

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 100
Summary for Reach 109R: Ditch 105
Inflow Area = 21.225 ac, 0.00% Impervious, Inflow Depth = 22.93" for AWA PMP -Synth event
Inflow = 530.86 cfs @ 2.84 hrs, Volume= 40.550 of
Outflow = 530.12 cfs @ 2.85 hrs, Volume= 40.550 af, Atten= 0%, Lag= 0.7 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 14.76 fps, Min. Travel Time= 1.1 min
Avg. Velocity = 4.78 fps, Avg. Travel Time= 3.3 min
Peak Storage= 34,122 cf @ 2.85 hrs
Average Depth at Peak Storage= 1.58'
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 '/' Top Width= 42.00'
Length= 950.0' Slope= 0.0442 '/'
Inlet Invert= 650.00', Outlet Invert= 608.00'
Reach 109R: Ditch 105
Hydrograph
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 I I I I I I I
I -1-1 1 -4-L-LL I I 1 1 1-1-t-4-L-LL I I I 1 1-1-t1-LL
■Inflow
530.86 cfs I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I 1 1 1
❑ Outflow
550
.�
1 I I I I T T T I 1 1 1 1 1 1 1 Inflow Area=2 11.225 ac
s30.12ds
i
500
ppWj Z �
/
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 •
450
V�� OU�� 0 ��SI
400
T
1 1 T� T
1 1 1 1 1 1 1 I I I I I 1 1 I I 1 1 1 1 n=I 0.0251
350
III + +III + +III + +
1 1 1 1 1 1 1 1 1 1 1 1 11 11 1 1 1 1 1 1 1 1 1 L1=950.011
0 300
11 1 T T 1 1 I 1 1 T T 1 I I� I/� In1
� ��
`L 250
-1-1 -1 --1-4 1-1- 1-1-1 -1 -4 -4 1-1- -1-1S1=4041 4 I-�
200
1-17TTTF 1T7r000c IitT
150
11 1 1 J 1 1 L L L L 1 11 1 L A I L L L L L I I 1 1-1 A 1 L L L-
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 I I I I I
100III
rt rt rt fi rIII rt rt rt rt fi rIII rt rt t fi L-
1I
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Pace 101
Summary for Reach 20613a: Channel 201
Inflow Area = 109.022 ac, 0.00% Impervious, Inflow Depth = 21.37" for AWA PMP -Synth event
Inflow = 2,203.17 cfs @ 3.16 hrs, Volume= 194.191 of
Outflow = 2,195.51 cfs @ 3.20 hrs, Volume= 194.191 af, Atten= 0%, Lag= 2.6 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 9.91 fps, Min. Travel Time= 3.0 min
Avg. Velocity = 2.54 fps, Avg. Travel Time= 11.8 min
Peak Storage= 398,968 cf @ 3.20 hrs
Average Depth at Peak Storage= 4.94'
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= 1,800.0' Slope= 0.0050 '/'
Inlet Invert= 597.00', Outlet Invert= 588.00'
Reach 20613a: Channel 201
Hydrograph
I_1_1_I
L 1 I L L L I_1_1_I
J 1 1 L L LI_1_1 _1 1 1 1 L L 1_1_1_1 J 1
i
1 1
1 1 --+++ 1-1-1
1+4+++�-I 11 1+++4--+I I I -I --1 T
2,400
2203.17cfs
1I -1I TI T T T T T 1-1-1
-1I TTT T TFI-1-1�-1 T T TTI-I-11-1 T T
23005.51
cfs
I
I____
IIIDwArea_022, a
�.a
2,200
___
2,100
I I+T + + I
IT
I I I + 4 + + +
&'T
2,000
�1�1
1,00
II
I I 1---M���m
1=f1,800 1 1alt Pd
1,700
1T+�I
-1
1 1 14T� 1 1 1 144+4- 1�0►.6C
1,600
T T T T T T 1-1-1-1
T T T T T T I-1-1-1 T T T T T+�5
1,500
6 1,400
1 1 1 1 1 1 1-1-1-1-1
--
1 1 1 1 1 1-1-1-1-1 1 I I JI' 1- 1 $
L_
7
1,300
-
I � T 4- � � � III
I � 4 T � � � III I -44 T � I1I-� T
3 1,200
-1 T T T T T T I-
I -I -1 T T T T T T 1- I -1 -1 T T T 01�05�f
i-°° 1,100
1,000
=1 - --
II I II I _I I I I I I I
--_
900
-
1 T I I k- 111
1 4 T P1+lapa�'I.}�IJSI
800
--1
rtrtlt- rl
1 1 IIrtTfirr_1 I I ITrtrtfi11 I I I_1T
700
-
- 1
IIIIII III
600
- - - - - - - -
- - - - - - - - - - - - - - - - - - - - -
500
400IlrtrtfirrlIIrtrtfilrlIrtrttfillII�rt
300
T-1 1 T T
j T T F I 1 7 T 1 1 1 1 1 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)
■ Inflow
■ Outflow

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 102
Summary for Reach 20613b: Channel 201
Inflow Area = 161.394 ac, 0.00% Impervious, Inflow Depth = 21.53" for AWA PMP -Synth event
Inflow = 3,258.58 cfs @ 3.15 hrs, Volume= 289.623 of
Outflow = 3,253.90 cfs @ 3.17 hrs, Volume= 289.623 af, Atten= 0%, Lag= 1.2 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 11.21 fps, Min. Travel Time= 1.9 min
Avg. Velocity = 2.74 fps, Avg. Travel Time= 7.7 min
Peak Storage= 365,585 cf @ 3.17 hrs
Average Depth at Peak Storage= 6.03'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,861.70 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 90.00'
Length= 1,260.0' Slope= 0.0052 '/'
Inlet Invert= 588.00', Outlet Invert= 581.50'
Reach 20613b: Channel 201
Hydrograph
3,600
3,400
3,200
3,000
ZI
3,253.90cfs
1111 + -t + + 111 1 + 4 + II1 1 + + + � 1111 J
3,258.58 cfs 1 -1 -t 11 1 1+ 4+++ I I 1 11 4++ - +I I I I)
-1 -1 � -4 1-1-1 -1 -4 4 + � Wtow-Area=16-♦1-3941 ao
1 1 1 J 44- 1-1-1 1 J 4
rrI
■ Inflow
0 Outflow
,
i
1 1 1 J 4 4 1-1-1 1 J 4 � T ' Il T IC I
2,800
1_1 _1 �- !- �- 1_ 1 _1 _1 �- -Wi(Vole
2,600
_-1121-fps
1_1_1 _L _LL 1_1_1_1 _L L_ _1 _I _L _L � L_ I_I_I_ :nj.0
2,400
1 1 I -1A _LL L L I 1 1 I -1 1+ L J L 1 1 1-1 -1 -11 J L CL=-O _02 A
2,200
JJJJJJLJ JJ1+LJL JJJJl�Jf120- _ni
t 2,000
-1 ) M I L L I-1-1 -1 J 1 1 L L L 1-1 -1 -1 -1 _L L I L 1-1- - J�
1,800
-1 __1A L L L L I_ 1-1 -1 --1 1 1 L L L I-1-1 -I L 1 i, ='FJI-0p52J /1
0
LL 1,600
I J A J L L L I I I J J -1 1 L L6-1-1 -1 I{
1,400
i
�J�ICj s
-1 __1A L L L L 1-1-1 -1 --1 1 1 L La a-CL� 7L 1 u
j
1,200
_I J L L - -I-I-I J L L-1-1-1-1 J J I I L L1-1-I 1
1,000
800
600
400
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 103
Summary for Reach 207R: Channel 202
Inflow Area = 48.990 ac, 0.00% Impervious, Inflow Depth = 20.61" for AWA PMP -Synth event
Inflow = 992.25 cfs @ 3.07 hrs, Volume= 84.132 of
Outflow = 986.54 cfs @ 3.15 hrs, Volume= 84.132 af, Atten= 1 %, Lag= 4.7 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 7.75 fps, Min. Travel Time= 4.4 min
Avg. Velocity = 1.95 fps, Avg. Travel Time= 17.3 min
Peak Storage= 257,634 cf @ 3.15 hrs
Average Depth at Peak Storage= 3.21'
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= 2,025.0' Slope= 0.0049 '/'
Inlet Invert= 591.50', Outlet Invert= 581.50'
Reach 207R: Channel 202
Hydrograph
1 1 I _ttfit I— I 1 1 fitt-��_1 I I 1�fitt�I 1 1 —1 -1
1 1 IT-1TTFFI I I 1TTTTTFI I I 177TTTI 11 I-1�
■Inflow
1,100
992.25cfs I_ I_ I_ I
■ Outflow
1,050
_I _I _I
986.54cfs I-1 1 1 1 1— 1 1 1 1 1IRfWW-1Area:1
4 9901 ad-
1,000
—I —I —I—I —I
950
i 1-1 -I -f + 4- 1 __ I- I -1 -1 T T 1-y _ _90-rilo
� 4-900 i I -I -I � + ♦- � _+I- I -I -I � + � �/ M1�'h��F oeoh �r#
850
i 1 1 IT-1T7rFI 11 -1 -1 T T T TFI I �T" F� �� rt
800
_ V� C�17-
700
1 1 1 1 T T 1 1 1 1 1 1 1 1 T 1 1 lAr I 1-
I_1_I--I-I-1-1-1-I-I-1 ��01.025
650
It 600
-I -4 + ♦ I-I-1 -1 + 1 - I - I -1 + L=250-��5V.
o 500
t - t t - - - - - - - I -I -� t t
L.I1�1v�r•YI
EME400
1V
-
�r00
350
1�_t4 L 1-1-1 1�TT 7�
300
—1 -4 + + I-1-1 —1 T + + - ­- I—I-1 —1 + + + 4- - I— I—I-1 ­4
250
—Itrtttl-r1—I-1-1trttttrl—I—I-1tttl-tl—I-1—I-1rt
200
inn
—ITTTTTTI 17TTTTTI IT -I rTl ITT
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 104
Summary for Reach 208R: Channel 202
Inflow Area = 247.345 ac, 0.00% Impervious, Inflow Depth = 21.48" for AWA PMP -Synth event
Inflow = 4,999.48 cfs @ 3.14 hrs, Volume= 442.850 of
Outflow = 4,985.87 cfs @ 3.17 hrs, Volume= 442.850 af, Atten= 0%, Lag= 1.7 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Max. Velocity= 12.27 fps, Min. Travel Time= 2.6 min
Avg. Velocity = 2.73 fps, Avg. Travel Time= 11.5 min
Peak Storage= 767,752 cf @ 3.17 hrs
Average Depth at Peak Storage= 7.67'
Bank -Full Depth= 10.00' Flow Area= 600.0 sf, Capacity= 8,514.04 cfs
30.00' x 10.00' deep channel, n= 0.025
Side Slope Z-value= 3.0 '/' Top Width= 90.00'
Length= 1,890.0' Slope= 0.0048 '/'
Inlet Invert= 581.50', Outlet Invert= 572.50'
$ t /
Reach 208R: Channel 202
Hydrograph
11 1 1 T 4-- 11 1 1 4 T- 1 1 1 1-4 4 4-4--11 1 1 A T
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
■ Inflow
5,500
4,999.48cfs I T T T T T T I T T T T T T 11 7 T T T T I T T
■Outflow
4,985.87
cfs Inflow Area=247.3451 as
5,000
/
1
4 11-11-1 4 4- 11FII �T-I-I-IIV��-4
4,500
-11 -4 -4 k- -1 -4
MaX eh=12.27 fps
4,000
i
-177T7TTI-I-I-1T7TT7-TI-I-I-177TTTI-1-1- T
n4 a5
3,500
1 1
3,000
111 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11-1_la 18�� �
- 1 T4- I T� � I 1 1 4I T 11 1-44�7I111404
3
III I I I I III I l s—_Io l 0 48 171
LL 2,500
-I T T T T T T I-1-1-1 T T T T T EII-1-1-1, T T T T I-II-11-I T
CapaCLITY7-8,514.04 cTs
2,000
-
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 III I I I
1,500
-1 I44--I 1 1 144--I 11 1-44T4-- 1 1 1 1-1-4
1,000
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
1 1 FTI 1 TTTTTTI TTTTTTI 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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HydroCAD®10.00-14 s/n 01723 ©2015 HydroCAD Software Solutions LLC Paae 105
Summary for Pond 10OP: SW 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 = 22.00" for AWA PMP -Synth event
Inflow =
4,530.57 cfs @
2.94 hrs,
Volume=
395.404 of
Outflow =
5,759.69 cfs @
2.93 hrs,
Volume=
395.934 af, Atten= 0%, Lag= 0.0 min
Primary =
108.32 cfs @
2.93 hrs,
Volume=
74.479 of
Secondary =
5,651.37 cfs @
2.93 hrs,
Volume=
321.455 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= 595.26' @ 2.93 hrs Surf.Area= 170,000 sf Storage= 2,078,019 cf (2,043,019 cf above start)
Plug -Flow detention time= 60.5 min calculated for 395.131 of (100% of inflow)
Center -of -Mass det. time= 59.7 min ( 257.7 - 198.0 )
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' 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 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=108.31 cfs @ 2.93 hrs HW=595.26' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Outlet Controls 108.31 cfs @ 24.82 fps)
Secondary OutFlow Max=5,650.35 cfs @ 2.93 hrs HW=595.26' TW=565.70' (Dynamic Tailwater)
L2=Custom Weir/Orifice (Orifice Controls 5,650.35 cfs @ 17.39 fps)

Allen CI 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 106
Pond 10OP: SW Detention Option 1
Hydrograph
I I I I I I I
.I + t I11
I I i
+ t +11
i i
+ + I11
l l l l l l l l l l l l l l l l l l
+ t L 11+ + t I11 -f + 1I
■Inflow
IJ+L1 1
5,759.69 ors
ILLLI
1-11LI
I I� ^LI -Jg1L LaI+I
■ Outflow
■primar
II� "I r"laf `T"I
■ Secondary
6,000 5,651.37cfs
III I I III
I I IIII
I I IIII
II I Pe�k EWV-�5951261
5,500 a
7cfs , L L 11_ �
1 L
J 1 L �_
11
Ige--
_�
—11
_� �+t� 0 ZNt 'I
5,000
1 1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
4,500
1 t 1- I —I
—I rt t� l—I
� rt� I —I
—I rt fi r l—I � rt fi I —I —I rt t r l—I
4,000
^y
J 1 L 1-1-1
-1 J- L I_
1 -a 1 L 1_
1 _I -L 1 L I_ 1 J_ L 1-1-1 -1 1 L 1_ 1
V 3,500
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
3,000
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
_0
LL
1-1 7 r 1-1-1
T T TI-1-1
7 r 1-1-1
T T r1-1T T T I-1-1 -T T r l—I
2,500
L L 111
L 1 L I1
1 L 111
L t L 11 L 1 L 111 A L L II
2,000
1,500
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HydroCAD®10.00-14 s/n 01723 ©2015 HydroCAD Software Solutions LLC Page 107
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 108
Pond 103P: SW Detention Option 2
Hydrograph
_
I I I I I ■ Inflow
� ■ Outflow
4.65 cfs I ■ Primary
5 4.65cfs I_I _ I I_I _ I I _ I_I I_ eak IeV= _ 1 6,661 ■ Secondary
1 1 More' �ei1 bbb �cf
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 I I I I I 1 1
4 1 1 1-f++ 1 1 1-t+ L I 1-1+ 1+ 1 1 1 1+ 1 1 1+++ I 1 1-1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
N g 11 1-t1L1 1 1 A -L L L I 1 -1 -1 L L 1 IJ1LL1 1 IL1L1—
1I 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 I I
3 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 I I I I
0
2
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 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 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 I I I I I I I I I I I I I I I I I
1 �
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HydroCAD®10.00-14 s/n 01723 ©2015 HydroCAD Software Solutions LLC Paae 109
Summary for Pond 104P: SW Detention Option 1 - Pond 1
Keeping pond below 25 feet in height and 50 acre-feet of storage to avoid dam classification
Inflow Area = 247.345 ac, 0.00% Impervious, Inflow Depth = 21.48" for AWA PMP -Synth event
Inflow =
4,985.87 cfs @
3.17 hrs,
Volume=
442.850 of
Outflow =
4,955.63 cfs @
3.21 hrs,
Volume=
443.379 af, Atten= 1 %, Lag= 2.7 min
Primary =
109.84 cfs @
3.21 hrs,
Volume=
79.283 of
Secondary =
4,845.80 cfs @
3.21 hrs,
Volume=
364.096 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= 587.85' @ 3.21 hrs Surf.Area= 170,360 sf Storage= 3,242,923 cf (3,207,923 cf above start)
Plug -Flow detention time= 55.0 min calculated for 442.576 of (100% of inflow)
Center -of -Mass det. time= 54.5 min ( 262.2 - 207.7 )
Volume
Invert Avail.Storage
Storage Description
#1
565.00' 5,317,515
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
600.00
171,000
1,610.0
3,239,495
5,317,515
237,779
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 20.00
Width (feet) 50.00 56.00 80.00 80.00
Primary OutFlow Max=109.83 cfs @ 3.21 hrs HW=587.84' TW=565.70' (Dynamic Tailwater)
L1=Culvert (Inlet Controls 109.83 cfs @ 22.38 fps)
Secondary OutFlow Max=4,845.45 cfs @ 3.21 hrs HW=587.84' TW=565.70' (Dynamic Tailwater)
L2=Custom Weir/Orifice (Weir Controls 4,845.45 cfs @ 8.77 fps)

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 110
Pond 104P: SW Detention Option 1 - Pond 1
Hydrograph
+ + 111
+
ii+ + + 111 4 + 1I
i l l
l l l l l l
l l l l l l l l l l
l l l l l l l l l l l l l l l l l l
4,985.87 cfs I I I I I
r4,955.63 cfs
I I I I I I I I I I
I I I I I I I I II� AI AII I I
51500
I A + + I- I
-I + + + 1- I -4 + + I-
1 1 1 1 1
1 1 1 1 1 1 1 1 1 1
1 1 I I I Peclk EW IV�987!85'
5 000 4,845.80 cfs
/
1 I I 111 I
I I 11L I 11 I I I I
11 I I �t�l Igel��? ,I
4,500
4,000
---------------------------
1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
3,500
1+ 1 I11
L 1 111 I11
L 1 111 1 111 A+ 11
y
V 3,000
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 I I I I I I
LL2,500
1 L L I11
L 1 L111 1 L I11
L L L11L 1 L I11 A 1 L 11
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 I I I I
2,000
1 1 1 1 1
1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1,500
J+ L L 1
I I I I
1 L 1 L 1 1-1 1 L L
I I I I I I I I I I
1 1 L L L 11 L 1 L L 1 1 A L 11
I I I I I I I I I I I I I I I I I I
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)
■ Inflow
■ Outflow
■ Primary
■ Secondary

Closure Plan HydroCAD
Prepared by AECOM
HvdroCAD® 10.00-14 s/n 01723
Allen CbE 25yr, 100yr, PMP
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
© 2015 HydroCAD Software Solutions LLC
Printed 9/25/2019
Pane 111
Summary for Pond 105P: Detention Pond Option 1 - Pond 2
Inflow Area = 47.194 ac, 0.00% Impervious, Inflow Depth = 22.93" for AWA PMP -Synth event
Inflow =
1,096.66 cfs @
2.93 hrs,
Volume=
90.162 of
Outflow =
775.54 cfs @
3.39 hrs,
Volume=
90.158 af, Atten= 29%, Lag= 27.4 min
Primary =
27.91 cfs @
4.37 hrs,
Volume=
44.500 of
Secondary =
755.99 cfs @
3.39 hrs,
Volume=
45.659 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3
Peak Elev= 627.53' @ 3.39 hrs Surf.Area= 5.911 ac Storage= 49.619 of
Plug -Flow detention time= 325.0 min calculated for 90.158 of (100% of inflow)
Center -of -Mass det. time= 324.9 min ( 519.5 - 194.6 )
Volume
Invert Avail.Storage Storage
Description
#1
614.00'
76.150 of Custom
Stage Data (Prismatic) Listed below
Elevation
Surf.Area
Inc.Store
Cum.Store
(feet)
(acres)
(acre-feet)
(acre-feet)
614.00
0.000
0.000
0.000
615.00
0.460
0.230
0.230
621.00
4.400
14.580
14.810
626.00
5.880
25.700
40.510
632.00
6.000
35.640
76.150
Device Routing Invert Outlet Devices
#1 Primary 614.00' 18.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 614.00' / 613.50' S= 0.0100 '/' Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
#2 Secondary 625.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28)
Head (feet) 0.00 1.00 25.00
Width (feet) 50.00 60.00 60.00
Primary OutFlow Max=27.91 cfs @ 4.37 hrs HW=625.51' TW=614.74' (Dynamic Tailwater)
L1=Culvert (Inlet Controls 27.91 cfs @ 15.79 fps)
Secondary OutFlow Max=755.93 cfs @ 3.39 hrs HW=627.53' TW=622.26' (Dynamic Tailwater)
L2=Custom Weir/Orifice (Weir Controls 755.93 cfs @ 5.14 fps)

Allen CI 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paoe 112
Pond 105P: Detention Pond Option 1 - Pond 2
Hydrograph
I I I I I
109 .66 cfs`PI
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
J1I 941I A1I
cI1,200
1I
(PI �I
AI
1I
+ I
t I
1 1 11
I 1 1 I11 1 1 1 1
1 I 1 1PebkIjE'6V_I�7.53rl
1,100
_
II1I I I
Se=��Q##11,000
775.54c1 1- 1-1-1
4 4 1-1-4 4 1-1-1
-4 4 1-1 4- 1-1-1 -4 1-1
900
I I
1
I I 1
800
755.99 cfs/
y 700
/ rt
rt rt rt
rt r rt fi rt rt r
J 1 L I-1-11
L LI_1J 1 L I-1-1
J L L1_IJ 1 L I-1-11 1 L1_1
3 600
1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
_o
U. 500
1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
I�+t- I 1
1-44 1 1 4 1
1 1-4 1 1 + 1 1 14+ 1 1
400
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 I I I I I I
300
0
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)
■ Inflow
Outflow
■ Primary
■ Secondary

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HydroCAD®10.00-14 s/n 01723 ©2015 HydroCAD Software Solutions LLC Paae 113
Summary for Pond 106P: North 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 = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min
Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 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= 586.00' Surf.Area= 0 sf Storage= 0 cf
Peak Elev= 609.00' @ 0.00 hrs Surf.Area= 0 sf Storage= 0 cf
Plug -Flow detention time= (not calculated: initial storage exceeds outflow)
Center -of -Mass det. time= (not calculated: no inflow)
Volume Invert Avail.Storage Storaqe Description
#1 609.00' 1,184,473 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)
609.00 0 0.0 0 0 0
610.00 75,000 1,140.0 25,000 25,000 103,420
622.00 120,000 1,400.0 1,159,473 1,184,473 158,139
Device Routing Invert Outlet Devices
#1 Primary 609.00' 24.0" Round Culvert
L= 50.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 609.00' / 608.00' S= 0.0200 '/' Cc= 0.900
n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf
#2 Secondary 620.00' 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=0.00 cfs @ 0.00 hrs HW=609.00' TW=608.00' (Dynamic Tailwater)
L1=Culvert ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=609.00' TW=608.00' (Dynamic Tailwater)
L2=Custom Weir/Orifice ( Controls 0.00 cfs)

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HydroCAD®10.00-14 s/n 01723 ©2015 HydroCAD Software Solutions LLC Paae 114
Pond 106P: North SW Detention Option 3
Hydrograph
Ery
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HydroCAD®10.00-14 s/n 01723 ©2015 HydroCAD Software Solutions LLC Page 115
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)
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD® 10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 116
Pond 107P: East SW Detention Option 3
Hydrograph
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
Ll
+ + I_ _ 1 L 1 1-1 p
3.12 .1 ds / �ak IL.IIev=�VVL���
3
Storage =3066 Hof
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 I I
i 1 1 1++ 1 1 1+++I- - + 1 1 T+ 1 1 1++ 1-1-1
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 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 I I I I I I
u+ 2
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 I I I I
3 1 1 1-f+t-1 1 1-t+FI- --f-I 1 1-f 1 1 1-t+-1
o
a
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 I I I I
1 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
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
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 117
Summary for Pond 108P: RAB Ex. Spillway (no storage)
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)

Closure Plan HydroCAD
Prepared by AECOM
HvdroCAD® 10.00-14 s/n 01723
Allen CbE 25yr, 100yr, PMP
Custom 6-hr Allen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
© 2015 HydroCAD Software Solutions LLC
Summary for Pond 200: RAB Outlet Pond (no storage)
Printed 9/25/2019
Pane 118
Inflow Area = 47.194 ac, 0.00% Impervious, Inflow Depth = 22.92" for AWA PMP -Synth event
Inflow =
775.54 cfs @
3.39 hrs,
Volume=
90.158 of
Outflow =
775.54 cfs @
3.39 hrs,
Volume=
90.158 af, Atten= 0%, Lag= 0.0 min
Primary =
156.46 cfs @
3.39 hrs,
Volume=
62.134 of
Secondary =
619.08 cfs @
3.39 hrs,
Volume=
28.025 of
Tertiary =
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
Peak Elev= 622.26' @ 3.39 hrs
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 '/' 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=156.46 cfs @ 3.39 hrs HW=622.26' TW=565.70' (Dynamic Tailwater)
t-1=RCP Culvert (Passes 156.46 cfs of 242.00 cfs potential flow)
t-2=42" Culvert Steep (Passes 156.46 cfs of 175.71 cfs potential flow)
t-3=42" Culvert Shallow (Inlet Controls 156.46 cfs @ 16.26 fps)
t-4=54" Culvert (Passes 156.46 cfs of 228.67 cfs potential flow)
Secondary OutFlow Max=619.02 cfs @ 3.39 hrs HW=622.26' TW=565.70' (Dynamic Tailwater)
5=Emergency Spillway (Weir Controls 619.02 cfs @ 5.52 fps)
Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=571.28' TW=565.70' (Dynamic Tailwater)
t-6=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 119
Pond 200: RAB Outlet Pond (no storage)
Hydrograph
1
1 L T L 1
1
I 4 I
I L L I I A T I I A T t- I
1 1 L
1-1
-4 T 1-1
4 1-1
—1 4 4- 1—
1-1 4 T 1-1 -4 T 1-1 -4+ 1- 1-1-1
775.54 cfs
775.54 cfs
+ —
+
w�+01
-7
1 1
rt t r1
I t L1
1 I -t t-1
-nt 7/ � — I— t 11
1
850
i
i
rt t r l—I
rt l—I
—I rt 1——I
rt rt Peak Efev�--622:26'-
800
i
T T T 1-1
T T T 1-1
—1 T T 1—
1-1 T T T 1-1 J T T I-1 T T T I-1-1
T
750
i
i
T T T 11
T T T 11
1 T T T
11 T T T 11 J T T 11 T T T I11
T
700
619.. cfs
1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1
650
i
600
i
550
i
^w 500
i
�450
I I II
I I I II
I I I I
II I I I II I I I II I I I III
I
i
11L1
1J1LI
1 —1 -1 L L
1 111L1 1J1L1 1J1LI
1-1
_0 400
u.
i
J 1 L 1-1
J 1 L 1-1
—1 1 L I_
1-1 1 L L 1-1 J 1 L 1-1 J 1 L 1-1-1
1
350
L T L 1
1 T 1 L 1-1
—1 1 L
1 1 L L L 1 1 A T L 1 1 A T t- I
1- L
300
i
cfs
T L
I 1 L 1
I L L 1
1 1 L L 1 1 A T L 1 1 A T t- I
1 1 L
250
i
200
i
150
100
0 2 4 6 8 10 1214 161820 2224 2628 3032 34 36 38 4042 4446 4850 52 54 56 5860 6264 6668 7072
Time (hours)
■ Inflow
■ Outflow
■ Primary
■ Secondary
■ Tertiary

Allen CbE 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 120
Summary for Link 102L: Lake Wylie/Catawba River
Inflow Area = 215.660 ac, 0.00% Impervious, Inflow Depth = 22.09" for AWA PMP -Synth event
Inflow = 5,761.00 cfs @ 2.93 hrs, Volume= 396.993 of
Primary = 5,761.00 cfs @ 2.93 hrs, Volume= 396.993 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
-1-1-1
4 T 4 k-I-1-1
-4 4+ �'
1-1 4- 1-I-1-1
■Inflow
5,761.00 cfs
❑ Primary
6,000 5,761.00ds
Inflow -ArelaC: 5-.6601
ac
5,500II
+ + i III+
+ +I
-II
5,000
4,500
I I T rt T T r r- I
1 1 T T rt T T T 1 1
1 1-1 T T T- r T I 1 1
1-1 rt
4,000 -
IIIIIIIIIII
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 I
I I I
N _
v3,500 I
_
I I T T T T T T I_
_ I I T T T T T T I I
I I T T T T T T I M
I T T
1
0
1 1--1J4 1
1 1--1 --4jT 1 1
1 1 1- 1 1 1
1
3,000
U.
2,500
2,000
-1 4 T 4 k- I-1-1
-4 4+ 1- 1-1
-1 --1-4 4 4- 1-1-1
-1 -4
_
1,500
I I I I I IIII
I I I I I IIIII
I I I I I IIIII
I I
1,000 -
+ + + iII+
+ + +
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 25yr, 100yr, PMP
Closure Plan HydroCAD Custom 6-hrAllen PMP - Synthetic AWA PMP -Synth Rainfall=25.70"
Prepared by AECOM Printed 9/25/2019
HvdroCAD®10.00-14 s/n 01723 ©2015 HvdroCAD Software Solutions LLC Paae 121
Summary for Link 104L: Lake Wylie/Catawba River
Inflow Area = 294.538 ac, 0.00% Impervious, Inflow Depth = 21.74" for AWA PMP -Synth event
Inflow = 5,619.26 cfs @ 3.26 hrs, Volume= 533.539 of
Primary = 5,619.26 cfs @ 3.26 hrs, Volume= 533.539 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
F 1 1
1 1 1 1 I I
I I I 1 F
■ Inflow
600°
5,619.26
cfs
4 4-� � I
-4 4��
1 A/�-4 4� � � I
1 A 4
Primary
5,619.26
cfs
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 Inflow Arela=294.5381 as
5,500
1 1 1 1 111
1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1
1 1
5,000
—'
—1 4 + +- I11
-t 4 + -k- 1 11
1 --1 4 4 111
1 --1 4
4,500
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 I I I
4,000
—1 4+ 4- 1-1-1
-4 4+ 1— 1-1
—1 4 4 4- 1 — I
— 1 —1 --1 1
3,500
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 I I
c 3,000
—I + t i—I—I
+
a
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
I I I I
2,500
2,000
I I fi+ t
- t t I
I I -f t I I I
I I
1,500
_
I I I I I I IIII
I I I I I IIIII
I I I I I IIIII
I I
1,000
1 —1 t fi t t t t I-1—I
I I I
t t t t t t 1— 1-1
I I I I I I I I I I
—1 t t t t t t 1-1-1
I I I I I I I I I I
—1 -1
I 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)

ATTACHMENT Cl-C
AWA PMP Study

PMP Input For Temporal Distributions
Leaend
USER INPUT VALUE
Duration
East
(hr)
PMP (in)
1hr - Local
10.6
2hr - Local
13.2
3hr - Local
16.7
6hr - Local
25.7
28.0
26.0
24.0
c 22.0
0 20.0
m 18.0
16.0
m
a 14.0
m 12.0
Ca
10.0
8.0
Q 6.0
4.0
2.0
0.0
East Local
6-Hour PMP
0 1 2 3 4 5 6
Time, Hours

6h, 9Mh 25.701
6h, Synthetic 25..
ZZ 7 ZZ
%:,77 tam",
III Ol
1.1 21 111 0.2 0.,
I. I, I- 1.
1 11 1
N, I " I I.
.1 1. .1. 0., 1.
I . 1. 0.2 0.. 0.
- :. 0', 0 1, 012
OIU 01,
111 1. 3, 00.
111 0,11; 1,1.1 101
I I �OO _ 0 1 1.,
11 0,347 0,11
- 131 .31, 1- 1-
0,11 0,112 0,111
0,0I OUO 0017
I 0,41 0,297 117
1 0- 0,11 111
2 �7' OU� 0,371 111
1 2:�l
3 " 0" 0,41 111
3:17 U �'l
3 1 0,42 0": OOU
3 ' 21 0,151 0,411 111
3 3:1 21 - Ill 001�1
0,117 Ol. 0 1
3.11 111 061, 0 1. 011
3 1 2. 0 U 0 2 ..1
3 '2 '31 0:1 0,:42 101
1 '41 0 1 0 ",
0:8 Il 2 1 ..1
2. 0,22 O'U I.
016
'71 0764 0,171 IOU
1 2. 0.. 0 :22 0.7
'1
`1 3" 0:. 0:1 0,01
5 311
`1
'1
0:1 O:�6 III
5
2 0,116 0,11 111
111
.1 "1
I. I.
1.. 11
1 U I U
1.. 111
352 11
- 037
4.0 III
04�
1. 141
1 1 11
:7
7.1 -
1.1 117
9.52 -
11.41 -
1 0
11.41 1.1
3." 1:�l
�I 1 0
U..
U..
111 0
UI
17..
U.. -
1111 0.
2, 12 �3
11,41 1.1
II OU
1116 01
100
11 *,151 *,�I *,.1
U 31 111 0.1 0.1
I" " I " I . III
1,11 11 011 0,112 0,111
111 1 011� 0'" 0.1
1,II I 011 Ol 0,11
1,�7 11 *171 0,11 0,111
1,71 1. 0,4, 0.,
III 1�, 1 .1 OU3 001,
- 0347 0'17 .0.
-1 0 " 0 0 7
111 11 0,11 0:" 0.:
III I 1 041 0,6. 0.1
2,67 11 �7.11 �OI4
111 1;1 �_l �OU
10. 11 �,OO �,12 �.l
117 11 111 *:1 OOI�
111 1', 0,42 0 7 0
III 2W 0,151 O:�l 0.0
11. 1�1 0,11 0:" 001,
111 1 , 0'1 0 1 0
3,67 2�, O:U 0:" 0,0.
III 2�, 0:,1 0:11 0,0.1
111 1 0 1 0 1 0
14, 0 0 0 1
2:, 0,61 O:�: O_
21 012� O:.l 0,01
�,U I , 0 47 0 0:
211 O:�I, 0:,7 0,011
1,�l 1 0 7, 0 2 0 1
111 1 , 0 1 0:" 0',
1,71 - 0 0 9' 0"�
, 0 0 1 000
11 11
1.11
1. 11
:,O I'W
11.1 1..1
11.1 ...
11.31 ...
U." 1.52
1311 111
U.. ...
1- 047
111 1.
17.11 -
17.97 ...
11.72 111
U.. ...
21.1 1.32
21:. 1:.l
0
21.1 1.11
21.. 111
1.
11.. 111
21.71 111
111, 1.
111 1.
23.. ...
23 1 1
1 0:1
1- OU
24.72 111
111 01
21:31 111
IIII II
1 1.
100 "1
OM I
11 0. 1. 0.
OU 31 11.,
Ill 11 1 1 1. 111
1,17 1 111 0,14� 00..
111 0112 0. 0.
II. 1. 0,111 0,11
1,67 11 111 0,11 0,11
1,71 1. IQ 00" 000,
111 0 1. 0.
- Ill 0.3.7 .0. 0 0,
-1 111 0,311 0,011 0,00�
III UO O_ 0'. 01
III I,, 011
2,67 UO I- O�,12 0,011
170 0,472 161 1117
III IN 0,11 1147 1117
3,17 11 111 O:�l O_.
111 1" ol 0 0
3,13 1. OU -2 0.
II. I'. - 0:1 0,001
111 1 ' 0" 0 2 0 1
3,67 2;0 0,611 111 111
111 2 O:U 0,:22 00.
111 .1 011 0,:16 00.1
141 0:. 0,:31; 0,�01
113 21 0,722 1142 111
�,U Ill 0.7. .11, .0.
- 11 1111 O:,l 0,01
1,�l Ill 111 0:1 00.1
1,13 321 111 0 1 0
1,71 1, 0 1 0 1 0 O�
0 6 0" 000;
11 11
11 11
111 11
1 1 015
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11 I:Wl
151 I:Wl
1:. :W.
0
1:11 1
II7 015
21 015
41
7" '72
�4:17 1:11
�l 71 1:,2
1:72
23:1 111
23:. 1:.
21:� I:Wl
. 0
21.53 -
U 71 2W
13.n IW
111 01
2411 1:1
24.22 -
, 0,
2471 I.W
IW
127 11
1.
OOT
01,,,-
01111- 111
111
111
OIT--
11 11
I.
d�lthz III
d,thc II
OIllh- 111
OIllh- L39
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llllh- 1.1
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0',"- 107
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ftlh- III
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dIllh- ..U-
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-
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TOO

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— L.- Ea8l LoeaI
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—fiM1r 981M1 < •fiM1r 90M
7
—8M1r1WM1 —__ •BM tOq
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�^ ZB
.a
is a z
iz g
E 10 %
a e

APPENDIX C2
Geotechnical

AECOM
Job Duke Allen Steam Station Project No. 60603204 Sheet 1 of 6
Description RAB Landfill Excavation Support Computed by ASZ Date 09/19/2019
Using DMM Shear Panels
Preliminary Global Stability Analysis Checked by Mu Date 09/27/2019
This Technical Memorandum presents the preliminary findings of evaluating the potential for utilizing
Deep Mixing Method (DMM) shear panels to support excavations associated with the closure -by -removal
of CCR of the Retired Ash Basin (RAB) at Allen Steam Station and retaining Phase I of the existing RAB
Landfill located on the east side of the RAB. AECOM performed a concept -level analysis to determine
approximate locations, dimensions and characteristics of the DMM system to support the northern and
western sides of the RAB Landfill. The configuration of the DMM system will be further optimized during
subsequent stages of the design.
The memorandum presents the results of the global slope stability analysis performed for the proposed
DMM retaining system along the north and west side of the RAB Landfill Ph.1. The following sections
summarize the methodology, assumptions, and results of the analyses. Figures and computer program
outputs are provided as attachments and are referenced herein.
I. OBJECTIVE
For final closure of the RAB Landfill, all existing ash within and below the RAB Landfill Ph. 1 footprint will
remain, while all existing ash located to the north (proposed future Ph. 2 footprint) and west of the RAB
Landfill Ph. 1 footprint will be removed. To accomplish this, an earth retaining system will be required to
support the planned excavations and maintain the stability of the RAB Landfill Ph.1. For this study, an
earth retaining system constructed using DMM shear panels was considered. The DMM system is
proposed to be constructed along the permitted limits of the northern and western perimeters of the RAB
Landfill Ph. 1 footprint.
The deep mixing method (DMM) is an in -situ soil treatment which blends native soils with cementitious
materials commonly referred to as binders. The blending typically occurs by means of drilled -in columns
(using equipment akin to structural drilled shafts but modified for deep mixing) that typically range in
diameter from 3 to 8 ft. Compared to native soils, the zone of improved soils has enhanced engineering
properties including higher shear strength and lower permeability. The properties obtained by DMM
depend on the characteristics of the original soils, the replacement ratio (amount of cementitious binders
used for a given volume of soil), and the design loading conditions.
AECOM determined conceptual design dimensions of a soil improvement zone, constructed using DMM
shear panels for the north and west limits of the RAB Landfill Ph.1 to maintain the stability of the Landfill
during closure of the RAB. The DMM zone will extend approximately 1,600 ft. along the north side of the
Landfill and 1,200 ft. along the west side of the Landfill. AECOM also performed preliminary slope stability
analyses to evaluate the DMM shear panels at two (2) critical design cross -sections (sections) within this
zone, one for each side of the Landfill.
AECOM designed the DMM stabilization zone based on the available subsurface and topographic
information for existing conditions. The DMM zone was sized to meet the safety factor for End -of -
Construction (short-term) loading condition.

A=COM
Job Duke Allen Steam Station Project No. 60603204 Sheet
Description RAB Landfill Excavation Support Computed by ASZ Date
Using DMM Shear Panels
Preliminary Global Stability Analysis Checked by MU Date
II. DEVELOPMENT OF ANALYTICAL CROSS SECTIONS
2 of 6
09/19/2019
09/27/2019
Two (2) design sections (DMM North Side and DMM West Side) were considered for the preliminary
design of the DMM panels (see Figure C2.1 below). These sections were selected at location where the
retained ash behind the DMM system would be deepest. The cross -sections were drawn in AutoCAD using
survey data from the site while also referencing relevant historic design drawings.
Figure C2.1— Location of Analytical Cross Sections
Stratigraphy
LAKE WYLID
'ATAWHA RIVER
VORMAL W.S.E.
565.7 Fr.
LAKE WYLIE 166-YEAR
FLOOD ELEVATION:
571.3 Fr.
The subsurface conditions associated with the design sections were established based on AECOM
subsurface explorations conducted as part of the Phase 2 evaluation (AECOM, 2018) as well as historical
subsurface explorations by S&ME (2008). The following stratigraphic layers were included in the slope
stability models:
• Ash Fill — Existing landfilled ash
• RAB Ash — Sluiced fly ash and bottom ash are located within the RAB, on the upstream sides of
the dikes. These materials are generally unconsolidated.

AECOM
Job Duke Allen Steam Station Project No. 60603204 Sheet 3 of 6
Description RAB Landfill Excavation Support Computed by ASZ Date 09/19/2019
Using DMM Shear Panels
Preliminary Global Stability Analysis Checked by Mu Date 09/27/2019
• Saprolite - This layer represents the native residual foundation soils derived from weathering of
the parent bedrock.
• Partially Weathered Rock (PWR) — PWR consists of residual material exhibiting N-values of 50
blows per 6 inches penetration or greater.
Phreatic Surface
Duke Energy currently monitors several observation wells/piezometers situated on and around
the Active Ash Basin (AAB) and the RAB. AECOM reviewed potentiometric maps (POT maps)
prepared by SynTerra (SynTerra, 2018) which were based on groundwater level measurements
from shallow observation wells made on September 11, 2017. The phreatic surface in SLOPE/W
was modeled using a piezometric line drawn at or near the levels indicated in the POT maps.
III. METHODOLOGY
Stability Analysis Approach
AECOM performed slope stability analysis using SLOPE/W 2016 of the Geostudio suite of programs. The
program uses 2-D limit equilibrium theory based on the method of slices according to Spencer's Method
to determine factors of safety for failure surface geometries. For the cross sections evaluated, circular and
block (i.e. non -circular) slip surface geometries were analyzed by defining entry/exit limits or search blocks
to develop the failure surfaces.
Loading Condition
AECOM evaluated the global slope stability for the end of construction loading condition. This case
represents undrained conditions for low -permeability ash materials or foundation soils (i.e. excess pore
water pressure is present because the soil has not had time to drain since being loaded) which may occur
upon completion of construction of the DMM stabilization system. Undrained (total stress) shear strength
parameters are used for the low -permeability materials such as the saturated RAB Ash materials and
Saprolite soils in the models. Drained (effective stress) shear strength properties were used for the Ash
Fill and RAB Ash materials above water table. Partially weathered rock (where present) was also modelled
with drained shear strength parameters as it is expected that the construction of the DMM system would
minimally affect the stresses within this material during construction.
The minimum required factor of safety for this loading condition is 1.30 based on the guidance given in
EM-1110-2-1902 (USACE 2003).
Material Properties — Ash and Soils
AECOM's analysis utilized material properties from the Phase 2 engineering report (AECOM, 2018). The
following table shows the shear strength parameters and unit weights used for each material model.

A=COM
Job Duke Allen Steam Station Project No. 60603204 Sheet 4 of 6
Description RAB Landfill Excavation Support Computed by ASZ
Using DMM Shear Panels
Preliminary Global Stability Analysis Checked by Mu
Date 09/19/2019
Date 09/27/2019
Table 1— Material Properties Used for "End of Construction" Loading Condition
Material
Effective (Drained) Shear
Strength Parameters
Total (Undrained) Shear
Strength Parameters
Unit
Weight
(pcf)
c (psf)
phi (0)
c (psf)
phi (0)
Ash Fill
25
26
--
--
90
RAB Ash
0
34
175
19
95
Sa prol ite
--
--
575
16
125
Partially Weathered Rock
0
35
--
--
135
Material Properties — DMM Zone
Material properties for the DMM zone were estimated for undrained conditions only. Information on the
drained composite shear strength of soil-DMM zones is limited in engineering literature. However, the
drained friction angles of the in -situ soils and the RAB Ash materials are relatively high and the drained
strength of the soil-DMM zone will be at least as high, if not higher, than the in -situ soil due to addition of
the cement -based DMM columns. These effects coupled together will likely add a considerable amount
of cohesion to the composite shear strength of the DMM zone.
For the current analysis, AECOM assumed that the DMM shear panels would be constructed based on an
area replacement ratio is 90%. Undrained shear strength for the DMM zone is typically developed by
taking a weighted average of the undrained shear strength of the DMM columns and the undrained shear
strength of the surrounding soil, based on the area replacement ratio. As an example, for a 35%
replacement ratio, the undrained strength of the DMM composite zone would be estimated as (0.35 x
DMM strength) + (0.65 x soil shear strength). However, in the slope stability models, we conservatively
assumed that the undrained shear strength of the DMM zone would be solely provided by the DMM shear
panels and the shear strength of the surrounding material was ignored.
The DMM shear strength was developed using guidance presented in Filz and Templeton (2009), which
states that the total stress cohesion intercept of the DMM zone should be one-half of the specified
unconfined compressive strength of the DMM columns, multiplied by 0.8 to account for the reduction
from peak unconfined strength to residual confined strength. Curing factors and variability factors
recommended by Filz and Templeton (2009) were not included, as it is planned that this project will
include a performance -based specification based on testing of the 28-day unconfined compressive
strength of the DMM columns, and will require additional columns to be added if the variability and/or
minimum strength criteria of the DMM columns is not met.
A DMM zone with a minimum unconfined compressive strength of 150 psi was considered for the analysis.
Using this design value and the Filz and Templeton (2009) recommendation discussed above, the
undrained shear strength of the DMM columns would be 8,640 psf (150 psi x 144 inz/ft2 x 0.5 x 0.8). This
strength is applicable only for the soils in which the DMM is installed/mixed and not to vary with depth,

A=COM
Job Duke Allen Steam Station Project No. 60603204 Sheet
Description RAB Landfill Excavation Support Computed by ASZ Date
Using DMM Shear Panels
Preliminary Global Stability Analysis Checked by MU Date
S of 6
09/19/2019
09/27/2019
as it is a strength value based on the Filz and Templeton (2009) criteria (and thereby may be exceeded in
some areas of the columns). In order to account for the 90% replacement ratio in the SLOPE/W stability
models, a composite design undrained shear strength of 7,776 psf (0.90 x 8,640 psf) was assigned to the
DMM Zone.
The dimensions of the DMM system were estimated by running several slope stability models and
iteratively changing the height, width and embedment depth into Saprolite of the DMM block in the model
until the minimum FOS for the End of Construction loading condition was met or exceeded.
IV. RESULTS
The preliminary DMM dimensions for both analytical sections are shown in Figures C2.2 and C2.3 below.
The resulting factors of safety are listed in Table 2.
89.5 ft
Figure C2.2 — DMM Dimensions for North DMM Stabilization System

A=COM
Job Duke Allen Steam Station Project No. 60603204 Sheet
Description RAB Landfill Excavation Support Computed by ASZ Date
Using DMM Shear Panels
Preliminary Global Stability Analysis Checked by MU Date
76 ft N
Figure C2.3 — DMM Dimensions for West DMM Stabilization System
6 of 6
09/19/2019
09/27/2019
Table 2 — Summary of Slope Stability Factors of Safety
Design Section
Loading
Minimum Required
Failure Type
Condition
FOS
North Side
West Side
End of
Circular
1.30
1.32
1.30
Construction
Block (Non -Circular)
1.31
1.32
V. REFERENCES
AECOM, 2018. Phase 2 Reconstitution of Ash Pond Designs Report (Rev. 4), Allen Steam Station. April 26,
2018.
Filz, G. and Templeton, E. (2009). Design Guide for Levee and Floodwall Stability Using Deep -Mixed Shear
Walls, February 10.
SynTerra (2018). Figure 6-10: Shallow Water Level Map - September, 2017. Duke Energy Carolinas, LLC,
Allen Steam Station, Mooresboro, North Carolina. January 26, 2018.
S&ME (2008). Duke Energy Allen Steam Station Landfill —Global Slope Stability Calculation. Marsh 3, 2008.
U.S. Army Corps of Engineers (USACOE, 2003). EM-1110-2-1902 Slope Stability. October, 2003.

ATTACHMENT A
Results of Slope Stability Analysis

Attachment A-1
RAB Landfill North Side DMM

Duke Energy Allen Steam Station
Gaston County, North Carolina
Conceptual Design of Excavation Support System for RAB Landfill
Using DMM Shear Panels
Global Stability Analysis - North Side
End -of -Construction Condition - Circular Failure
720 F--
695
:�Le7
645
0
620
aD
w
595
545
Saprolite (Undrained)
Color
Name
Model
Unit
Cohesion'
Phi'
Cohesion
Weight
(psf)
(0)
(psf)
(pcf)
Ash Fill
Mohr -Coulomb
90
25
26
DMM - 90% Undrained (Phi=O)
135
7,776
Replacement
RAB Ash Mohr -Coulomb
95
0
34
RAB Ash
Mohr -Coulomb
95
175
19
(Undrained)
Saprolite Mohr -Coulomb
125
575
16
(Undrained)
091111
Ash Fill
RAB Ash
RAB Ash (Undrained)
-275 -225 -175 -125 -75 -25 25 75 125 175
r1 i c++� r ^r%

Duke Energy Allen Steam Station
Gaston County, North Carolina
Conceptual Design of Excavation Support System for RAB Landfill
Using DMM Shear Panels
Global Stability Analysis - North Side
End -of -Construction Condition - Block (Non -Circular) Failure
720 F--
695
tee]
645
0
620
aD
w
595
545
Saprolite (Undrained)
1.31
Color
Name
Model
Unit
Cohesion'
Phi'
Cohesion
Weight
(psf)
(0)
(psf)
(pcf)
Ash Fill
Mohr -Coulomb
90
25
26
DMM - 90%
Undrained (Phi=O)
135
7,776
Replacement
Mohr -Coulomb
RAB Ash
95
0
34
RAB Ash
Mohr -Coulomb
95
175
19
(Undrained)
Saprolite
Mohr -Coulomb
125
575
16
(Undrained)
-275 -225 -175 -125 -75 -25 25 75
rl i e++.� r, r+�
Ash Fill
RAB Ash
i (Undrained)
125
175

Attachment A-2
RAB Landfill West Side DMM

Duke Energy Allen Steam Station
Gaston County, North Carolina
Conceptual Design of Excavation Support System for RAB Landfill
Using DMM Shear Panels
Global Stability Analysis - West Side
End -of -Construction Condition - Circular Failure
1.32
700
675
650
p 625
C6
600
I� w
----- -----------------------
575
550
- I -I -
Partially Weathered Dock
-300 -250 -200 -150 -100 -50
Color
Name
Model
Unit
Weight
(pcf)
Cohesion'
(psf)
Phi'
(0)
Cohesion
(psf)
Ash Fill
Mohr -Coulomb
90
25
26
DMM - 90% Replacement
Undrained (Phi=O)
135
7,776
Partially Weathered Rock
Mohr -Coulomb
135
0
35
RAB Ash (Undrained)
Mohr -Coulomb
95
175
19
Saprolite (Undrained)
Mohr -Coulomb
125
575
16
h Fill
Ash (Undrained)
Saprolite (Undrained)
0 50
Distance
100 150 200 250 300

Duke Energy Allen Steam Station
Gaston County, North Carolina
Conceptual Design of Excavation Support System for RAB Landfill
Using DMM Shear Panels
Global Stability Analysis - West Side
End -of -Construction Condition - Block (Non -Circular) Failure
700
675
650
p 625
C6
W
600
----- ----------------------
575�_7lb,
550
Partially Weathered Dock
-300 -250 -200 -150 -100 -50
Color
Name
Model
Unit
Weight
(pcf)
Cohesion'
(psf)
Phi'
(0)
Cohesion
(psf)
Ash Fill
Mohr -Coulomb
90
25
26
DMM - 90% Replacement
Undrained (Phi=O)
135
7,776
Partially Weathered Rock
Mohr -Coulomb
135
0
35
RAB Ash (Undrained)
Mohr -Coulomb
95
175
19
Saprolite (Undrained)
Mohr -Coulomb
125
575
16
1.32
•
h Fill
naraine
Saprolite (Undrained)
0 50
Distance
100 150 200 250 300

APPENDIX C3
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
10/23/19
Checked by
ANR
Date
10/25/19
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.
- Fill: Soil buttress construction on the exterior side of the proposed DMM (slope
stabilization system) along the northern and western perimeter of the RAB Landfill.
- 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
Description
Duke Energy —Allen Closure
Soil Borrow Quantities
Closure by Excavation
Project No.
60572629
Sheet
2 of 2
Computed by
AMC
Date
10/23/19
Checked by
ANR
Date
10/25/19
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
792,000
CY
- 670K CY fill for DMM soil buttress construction
- 122K CY fill for backfill of CbE areas
RAB soil surplus
16,000
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)
369,000
CY
Assumptions:
1. No adjustments were used for material swelling, shrinkage, settlement, and waste.
2. Material quantities for operation or closure of the RAB Landfill are excluded.
3. Material quantities for construction of the proposed AAB Landfill 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.