HYDRAULIC MODELING ANALYSIS AND DESIGN …

PICAYUNE STRAND RESTORATION PROJECT SOUTHWEST PROTECTION FEATURE JANUARY 2020

HYDRAULIC MODELING ANALYSIS AND DESIGN DOCUMENTATION REPORT

Last Updated: February 2020 Jacksonville District

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DDR - Picayune Strand Restoration Project Southwest Protection Feature Hydraulic Modeling Analysis

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TABLE OF CONTENTS

1. INTRODUCTION ................................................................................................................... 1 2. PROJECT DESCRIPTION ........................................................................................................ 1 2.1 LOCATION, SIZE, AND HISTORY ..................................................................................... 1 2.2 SCOPE OF STUDY ........................................................................................................... 4 3. HYDRAULIC MODEL DESCRIPTION AND DEVELOPMENT .................................................... 4 3.1 GENERAL METHODOLOGY ............................................................................................ 5 3.2 DIGITAL ELEVATION MODEL ......................................................................................... 5 3.3 DEVELOPMENT OF THE HYDRAULIC MODEL ................................................................ 7 3.3.1 Cross-Section Elevation Data .................................................................................. 7 3.3.2 Manning’s “n” Values ............................................................................................. 9 3.3.3 Bridges and Culverts ............................................................................................. 11 3.3.4 Inline Structures .................................................................................................... 13 3.3.5 Lateral Structures .................................................................................................. 13 3.3.6 2D Areas ................................................................................................................ 14 3.3.7 Internal 2d Area Connections ............................................................................... 15 3.3.8 Boundary Conditions............................................................................................. 15 4. HYDRAULIC DESIGN SWPF ................................................................................................ 22 4.1 SWPF DESIGN OVERVIEW ........................................................................................... 22 4.2 PROTECTION LEVEE ..................................................................................................... 24 4.3 CONVEYANCE CANAL .................................................................................................. 26 4.4 CONVEYANCE STRUCTURES ........................................................................................ 28 5. RESULTS OF HYDRAULIC ANALYSIS ................................................................................... 31 5.1 5-YEAR STORM EVENT SIMULATION .......................................................................... 31 5.1.1 Canal Water Elevations ......................................................................................... 31 5.1.2 Bridge and Culvert Flows ...................................................................................... 33 5.2 10-YEAR STORM SIMULATIONS .................................................................................. 36 5.2.1 Canal Water Elevations ......................................................................................... 36 5.2.2 Bridge and Culvert Flows ...................................................................................... 38 5.2.3 10-Year Storm Simulations with Flow Cap Increase ............................................. 42 5.3 25-YEAR STORM SIMULATIONS .................................................................................. 44 5.3.1 Canal Water Elevations ......................................................................................... 44 5.3.2 Bridge and Culvert Flows ...................................................................................... 46 5.3.3 25-Year Storm Simulations with Flow Cap Increase ............................................. 50 5.4 100-YEAR STORM SIMULATIONS ................................................................................ 52 5.4.1 Canal Water Elevations ......................................................................................... 52 5.4.2 Bridge and Culvert Flows ...................................................................................... 54 6. DISCUSSION OF RESULTS .................................................................................................. 58 7. REFERENCES ...................................................................................................................... 59 8. LIST OF ABBREVIATIONS ................................................................................................... 60


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LIST OF TABLES

TABLE 3.2-1 SUMMARY OF DEM DATA ......................................................................................................... 5 TABLE 3.3-1 BRIDGES MODELED ................................................................................................................. 11 TABLE 3.3-2 CULVERTS MODELED .............................................................................................................. 12 TABLE 3.3-3 LATERAL STRUCTURES IN MODEL .......................................................................................... 14 TABLE 3.3-4 2D AREAS CELL SPACING ......................................................................................................... 15 TABLE 3.3-5 PERMITTED DRAINAGE DISCHARGE FOR FARM ..................................................................... 16 TABLE 3.3-6 SUMMARY OF HEC-RAS 1D BOUNDARY CONDITIONS ............................................................ 16 TABLE 4.2-1 LEVEE SUMMARY TABLE ........................................................................................................ 25

LIST OF FIGURES

FIGURE 2.1-1 SITE LOCATION MAP .............................................................................................................. 2 FIGURE 2.1-2 PSRP FEATURES MAP ............................................................................................................. 3 FIGURE 3.2-1 DIGITAL ELEVATION MODEL (DEM) ........................................................................................ 6 FIGURE 3.2-2 DETAILED VIEW OF DEM WITH BURNED IN CANALS .............................................................. 7 FIGURE 3.3-1 1D REACHES IN HEC-RAS MODEL ............................................................................................ 8 FIGURE 3.3-2 CENTRAL FARM DRAINAGE DITCH INVERT PROFILE ............................................................... 8 FIGURE 3.3-3 EAST FARM DRAINAGE DITCH INVERT PROFILE ...................................................................... 9 FIGURE 3.3-4 US41 DRAINAGE DITCH INVERT PROFILE ................................................................................ 9 FIGURE 3.3-5 LOCATIONS OF MODELED CULVERTS ................................................................................... 12 FIGURE 3.3-6 LOCATIONS OF MODELED CULVERTS AND BRIDGES ............................................................ 13 FIGURE 3.3-7 US41 MODELED AS LATERAL STRUCTURE ........................................................................... 14 FIGURE 3.3-8 HEC-RAS MODEL 2D AREAS.................................................................................................. 15 FIGURE 3.3-9 HEC-RAS 1D INFLOW BOUNDARY CONDITIONS ................................................................... 17 FIGURE 3.3-10 DESERET PERMIT 070314-9 FLOW CAP .............................................................................. 18 FIGURE 3.3-11 LIPMAN PERMIT 11-00097 FLOW CAP ................................................................................ 18 FIGURE 3.3-12 LIPMAN PERMIT 11-00076 FLOW CAP ................................................................................ 19 FIGURE 3.3-13 NORTH STAGE BOUNDARY CONDITION FOR WITH AND WITHOUT PROJECT (25 YR

STORM) ................................................................................................................................................ 20 FIGURE 3.3-14 EAST STAGE BOUNDARY CONDITION FOR WITH AND WITHOUT PROJECT (25 YR STORM)

............................................................................................................................................................. 20 Figure 3.3-15 HEC-RAS 2D MODEL BOUNDARY CONDITIONS .................................................................... 21 FIGURE 4.1-1 SWPF DESIGN FEATURES ...................................................................................................... 23 FIGURE 4.2-1 LEVEE GAP LOCATION .......................................................................................................... 24 FIGURE 4.2-2 SWPF LEVEE PROFILE ........................................................................................................... 25 FIGURE 4.3-1 CONVEYANCE CANAL MAXIMUM COMPUTED WATER PROFILE FOR 5, 10, 25 AND 100 YR

STORMS ............................................................................................................................................... 26 FIGURE 4.3-2 DEM WITH CONVEYANCE CANAL BURNED IN ..................................................................... 27 FIGURE 4.3-3 CROSS SECTION OF EAST FARM DITCH AND PROPOSED CONVEYANCE CANAL .................. 27 FIGURE 4.4-1 PROPOSED CULVERT LOCATIONS NEAR 6LS FARM ............................................................. 28 FIGURE 4.4-2 WITH PROJECT CONDITION FLOW VECTORS DOWNSTREAM 6LS FARM ............................ 29 FIGURE 4.4-3 PROPOSED CULVERT LOCATIONS NEAR CR92 ..................................................................... 30 FIGURE 4.4-4 WITH PROJECT CONDITION FLOW VECTORS NEAR CR92 ..................................................... 30 FIGURE 5.1-1 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATION FOR WITH AND WITHOUT

PROJECT (5 YR STORM EVENT) ............................................................................................................ 31


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FIGURE 5.1-2 CENTRAL FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT PROJECT (5 YR STORM EVENT) ........................................................................................... 32

FIGURE 5.1-3 US41 DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT PROJECT (5 YR STORM EVENT) ............................................................................................................ 32

FIGURE 5.1-4 BRIDGE 37 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (5 YR STORM) ........... 33 FIGURE 5.1-5 BRIDGE 39 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (5 YR STORM) .......... 34 FIGURE 5.1-6 BRIDGE 45 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (5 YR STORM) ........... 34 FIGURE 5.1-7 INDIAN VILLAGE RD CULVERT COMPUTED FLOWS WITH AND WITHOUT PROJECT (5 YR

STORM) ................................................................................................................................................ 35 FIGURE 5.1-8 PROPOSED US41 CULVERT COMPUTED FLOWS (5 YR STORM) .......................................... 35 FIGURE 5.1-9 PROPOSED CR92 CULVERT COMPUTED FLOWS (5 YR STORM) ........................................... 36 Figure 5.2-1 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT

PROJECT (10 YR STORM) ...................................................................................................................... 37 FIGURE 5.2-2 CENTRAL FARM DITCH MAXIMUM COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT

(10 YR STORM) ..................................................................................................................................... 37 FIGURE 5.2-3 US41 DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT

PROJECT (10 YR STORM) ...................................................................................................................... 38 FIGURE 5.2-4 BRIDGE 37 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (10 YR STORM) ......... 39 FIGURE 5.2-5 BRIDGE 39 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (10 YR STORM) ......... 39 FIGURE 5.2-6 BRIDGE 45 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (10 YR STORM) ......... 40 FIGURE 5.2-7 INDIAN VILLAGE RD CULVERT COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (10

YR STORM) ........................................................................................................................................... 40 FIGURE 5.2-8 PROPOSED US41 CULVERT COMPUTED FLOWS (10 YR STORM) ........................................ 41 FIGURE 5.2-9 PROPOSED CR92 CULVERT COMPUTED FLOWS (10 YR STORM) ......................................... 41 FIGURE 5.2-10 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND

WITHOUT PROJECT (10 YR STORM FLOW CAPPED AT 540 CFS) .......................................................... 42 FIGURE 5.2-11 CENTRAL FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND

WITHOUT PROJECT (10 YR STORM FLOW CAPPED AT 540 CFS) .......................................................... 43 FIGURE 5.2-12 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND

WITHOUT PROJECT (10 YR STORM FLOW CAPPED AT 770 CFS) .......................................................... 43 FIGURE 5.2-13 CENTRAL FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND

WITHOUT PROJECT (10 YR STORM FLOW CAPPED AT 770 CFS) .......................................................... 44 FIGURE 5.3-1 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT

PROJECT (25 YR STORM) ...................................................................................................................... 45 FIGURE 5.3-2 CENTRAL FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND

WITHOUT PROJECT (25 YR STORM) ..................................................................................................... 45 FIGURE 5.3-3 US41 DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT

PROJECT (25 YR STORM) ...................................................................................................................... 46 FIGURE 5.3-4 BRIDGE 37 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (25 YR STORM) ......... 47 FIGURE 5.3-5 BRIDGE 39 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (25 YR STORM) ......... 47 FIGURE 5.3-6 BRIDGE 45 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (25 YR STORM) ......... 48 FIGURE 5.3-7 INDIAN VILLAGE RD CULVERTS COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (25

YR STORM) ........................................................................................................................................... 48 FIGURE 5.3-8 PROPOSED US41 CULVERT COMPUTED FLOWS (25 YR STORM) ......................................... 49 FIGURE 5.3-9 PROPOSED CR92 CULVERT COMPUTED FLOWS (25 YR STORM) ......................................... 49 FIGURE 5.3-10 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND

WITHOUT PROJECT (25 YR STORM FLOW CAPPED AT 540 CFS) .......................................................... 50


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FIGURE 5.3-11 CENTRAL FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT PROJECT (25 YR FLOW CAPPED AT 540 CFS) ...................................................................... 51

FIGURE 5.3-12 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATION FOR WITH AND WITHOUT PROJECT (25 YR STORM FLOW CAPPED 770 CFS) ................................................................................ 51

FIGURE 5.3-13 CENTRAL FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT PROJECT (25 YR STORM FLOW CAPPED AT 770 CFS) .......................................................... 52

FIGURE 5.4-1 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT PROJECT (100 YR STORM) .................................................................................................................... 53

FIGURE 5.4-2 CENTRAL FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT PROJECT CONDITIONS (100 YR STORM) ............................................................................. 53

FIGURE 5.4-3 US41 DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT PROJECT CONDITIONS (100 YR STORM) .............................................................................................. 54

FIGURE 5.4-4 BRIDGE 37 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (100 YR STORM) ....... 55 FIGURE 5.4-5 BRIDGE 39 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (100 YR STORM) ........ 55 FIGURE 5.4-6 BRIDGE 45 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (100 YR STORM) ....... 56 FIGURE 5.4-7 INDIAN VILLAGE RD CULVERTS COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT

(100 YR STORM) ................................................................................................................................... 56 FIGURE 5.4-8 PROPOSED US41 CULVERT COMPUTED FLOWS (100 YR STORM) ....................................... 57 FIGURE 5.4-9 PROPOSED CR92 CULVERT COMPUTED FLOWS (100 YR STORM) ....................................... 57

DDR - Picayune Strand Restoration Project Southwest Protection Features Hydraulic Modeling Analysis

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1. INTRODUCTION Hydraulic analysis is required for the Picayune Strand Restoration Project (PSRP) Southwest Protection Feature (SWPF). This analysis is required to demonstrate that implementation of the PSRP will not result in reduction in the level of service for flood protection for the 6Ls Farm as part of Section 601(h)(5) or “Savings Clause” of the 2000 WRDA. This report documents the hydraulic analysis for the Southwest Protection Feature (SWPF) under the without-project PSRP and with-project PSRP conditions. A Hydrologic Engineering Center - River Analysis System (HEC-RAS) combined one‐dimensional and two-dimensional (1D/2D) unsteady‐flow routing model was used for the hydraulic analysis. HEC-RAS Version 5.0.6 was used for the analysis. 2. PROJECT DESCRIPTION 2.1 LOCATION, SIZE, AND HISTORY The PSRP consists of approximately 94 square miles located between Interstate 75 and US Highway 41. It is situated southwest of the Florida Panther National Wildlife Refuge, north of Ten Thousand Island National Wildlife Refuge and Collier Seminole State Park, east of the Bell Meade Conservation and Recreational Lands Project Area, and west of the Fakahatchee Strand State Preserve. The location of the PSRP is shown in FIGURE 3.3.1-1. A map showing the project features is shown in FIGURE 3.3.1-2. The 2004 Final Project Implementation Report and Environmental Impact Statement (PIR/EIS) authorized the features of the study. The PSRP includes degrading over 200 miles of roadways, constructing 83 plugs in 4 major drainage canals (Miller, FAKA Union, Merritt, Prairie Canals), and the construction of 3 pump stations with tieback levees and spreader berms. The SWPF is a component of the overall PSRP, located in the southwestern portion of Collier County.


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FIGURE 3.3.1-1 SITE LOCATION MAP


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FIGURE 3.3.1-2 PSRP FEATURES MAP


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2.2 SCOPE OF STUDY The preliminary hydraulic and hydrologic (H&H) analysis used for the 2004 Final PIR/EIS showed an increase in water levels for the floodplain areas adjacent to the 6Ls Farms when operating the PSRP. The Southwest Protection Features (SWPF) was designed to prevent an increase in water levels on the 6Ls Farms due to the PSRP. More detailed H&H analysis were subsequently performed using the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) Model. The GSSHA modeling proposed additional features for the SWPF including a levee gap (near US41), a seepage/conveyance canal interior to the protection levee and a new opening under US41. The scope of the current modeling effort is to further refine features proposed in the GSHHA Model and provide more detail design for these features. 3. HYDRAULIC MODEL DESCRIPTION AND DEVELOPMENT The Hydrologic Engineering Center’s River Analysis System (HEC-RAS) 1D/2D Model, Version 5.0.6 (released November 2018) modeling software was used for analysis and mapping. HEC-RAS 2D flow modeling advantage and capabilities include:

1. The ability to perform 1D, 2D only, or combined 1D and 2D modeling. 2. The 2D equation solver uses an Implicit Finite Volume algorithm. 3. Can solve either 2D Diffusion Wave or 2D Full Saint Venant Equations. 4. The 1D and 2D solution algorithms are tightly coupled on a time step by time step basis (or even

iteration by iteration). 5. The software was designed to use Unstructured and Structured Computational Meshes. The

outer boundary is defined with a multi-point polygon. 6. The underlying terrain and the computational mesh are pre-processed in order to develop

detailed Hydraulic Property Table of the Cells and the Cell Faces. 7. Mapping of the 1D/2D inundation area and animations of the flooding can be done right inside of

RAS using RAS-Mapper. 8. The 2D flow computations take advantage of multi-processors. 9. 64 Bit and 32 Bit Computation Engines are used.

The SWPF HEC-RAS model combines 1D and 2D unsteady-flow hydrodynamic routing. 2D unsteady-flow routing used Diffusion Wave equations. The 2D flow areas in the HEC-RAS model were used in a number of ways including:

1. Detailed 2D channel modeling 2. Detailed 2D channel and floodplain modeling 3. Combined 1D channels with 2D floodplain areas 4. Combined 1D channels/floodplains with 2D flow areas behind levees 5. Multiple 2D flow areas in the same geometry 6. Directly connect multiple 2D flow areas with hydraulic structures

2D flow modeling is accomplished by adding 2D flow area elements into the model similar to adding a storage area. A structured 2D computational mesh of nominal cell size is first generated. Break lines for levees, roads and other features are then used to further define the mesh. Boundary cells vary in shape and size to follow the detailed polygon boundary. Interior cells can also vary in shape and size, as for the cells around the break lines. The computational cells can be triangles, rectangles, or elements with up to eight sides.


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The 2D computation mesh is preprocessed into an elevation–volume curve for each cell, and a series of hydraulic property curves for each cell face (elevation vs. wetted perimeter, area, and roughness). These relationships are derived from the details of the underlying terrain used for the model. Each grid cell face is like a detailed cross section so the flow of water into, through, and out of a cell is controlled by the details of these face properties and the cell elevation-volume relationship. The benefit of this approach is increased hydraulic details at the cell level instead of models that use a single elevation for each cell and face. With HEC-RAS, users can have much larger cells, but still retain significant hydraulic detail within a cell. HEC-RAS cells can be partially wet so water does not have to cover the entire cell and can move through a portion of the cell. 3.1 GENERAL METHODOLOGY The purpose of this hydraulic modeling is to develop a design for the SWPF. The SWPF design will prevent restoration flows from the PSRP from impacting the stormwater drainage capabilities for the 6Ls farm. The model includes both 1D channel features and 2D topographic storage areas. Hydraulic analyses were simulated for design storms: 5-, 10-, 25- and 100-year. The model scenarios performed:

1. Without project conditions simulation for the 5-, 10-, 25- and 100-year storm events. 2. With project conditions simulations for the 5-, 10-, 25- and 100-year storm events.

3.2 DIGITAL ELEVATION MODEL The SWPF HEC-RAS model uses a digital elevation model (DEM) that was created as a mosaic of:

1. 2007 Florida Department of Emergency Management (FDEM) Collier County aerial light detection and ranging (LiDAR) data.

2. Cross-section survey data collected by USACE Jacksonville District in 2018 (Survey No. 18-099). The SWPF DEM covers approximately 210 square miles. HEC-RAS is used in conjunction with specific geometry files to modify the base terrain to a terrain version that then represents the with project features. The model DEM is shown in FIGURE 3.3.1-1. A close up view of the DEM with canal features burned in is shown in FIGURE 3.3.1-2. The data, source, and description are summarized in TABLE 3.2-1.

TABLE 3.2-1 SUMMARY OF DEM DATA

Data Description and Source Base DEM 2007 FDEM Collier County LiDAR data Surveyed Cross Section Data

Survey performed in 2018. Cross-section collected in the 6Ls Farm drainage canals and the US-41 ditch.

Resolution 5 foot x 5 foot Coordinate System Florida State Plane East Zone Horizontal Datum North American Datum 1983 2011 Realization (NAD83 – 2011) Elevation Datum North American Vertical Datum 1988 (NAVD88) Elevation Unit US Survey Feet


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FIGURE 3.3.1-1 DIGITAL ELEVATION MODEL (DEM)


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FIGURE 3.3.1-2 DETAILED VIEW OF DEM WITH BURNED IN CANALS

3.3 DEVELOPMENT OF THE HYDRAULIC MODEL Channel and floodplain information required by the HEC-RAS model was extracted from the DEM using the RAS Mapper tool. The geometric data generated from RAS Mapper included the canal system schematic, station-elevation points for cross-sections, reach lengths between cross-sections, location and station-elevation information for lateral and inline structures, and elevation-storage information for 2D storage areas. Additional data was entered into the HEC-RAS model based on survey data, information gathered from available documentation and/or from using standard engineering equations to estimate model parameters. The following paragraphs describe the HEC-RAS geometry data in more detail. 3.3.1 CROSS-SECTION ELEVATION DATA The HEC-RAS 1D reaches include cross-sections cut from the DEM data. The data contained information below the water surface based on the 2018 cross section survey data. 1D canal reaches in the model include; US41, central and eastern farm drainage ditches. The locations for the 1D model reaches are shown in FIGURE 3.3.1-1. The channel invert elevations for the 1D model reaches are shown in FIGURE 3.3.1-2 through FIGURE 3.3.1-4.


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FIGURE 3.3.1-1 1D REACHES IN HEC-RAS MODEL

FIGURE 3.3.1-2 CENTRAL FARM DRAINAGE DITCH INVERT PROFILE


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FIGURE 3.3.1-3 EAST FARM DRAINAGE DITCH INVERT PROFILE

FIGURE 3.3.1-4 US41 DRAINAGE DITCH INVERT PROFILE

3.3.2 MANNING’S “N” VALUES Manning’s n roughness values in the HEC-RAS 2D model were assigned based on land use consistent with the roughness values from the calibrated Gridded Surface Subsurface Hydrologic Analysis (GSSHA) Model. ArcGIS land use data from the South Florida Water Management District (SFWMD) was converted into a land use file used within the HEC-RAS 2D model. Manning’s n values for the dataset used in the HEC-RAS model are shown in Table 3.3.2. For the 1D reaches a Manning’s n value of 0.032 was assigned for the farm drainage ditch and 0.05 for the US41 drainage ditch. These values were based on observations from the field. The farm ditches were well maintained compared to the US41 ditch which was heavily vegetated along the banks.


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TABLE 3.3.2: MANNING’S N VALUES USED FOR LAND CLASSIFICATIONS Land Classification Base Manning's n abandoned groves 0.08 aquaculture 0.05 cabbage palm 0.10 cabbage palm wetland 0.10 channelized waterways canals 0.04 commercial and services 0.05 cypress 0.26 cypress mixed hardwoods 0.15 cypress pine cabbage palm 0.15 disturbed land 0.07 embayments not opening directly to ocean 0.05 embayments opening directly to ocean 0.05 fallow cropland 0.04 fixed family units 0.10 freshwater marshes graminoid prairie 0.10 golf course 0.08 herbaceous dry prairie 0.10 high density under construction 0.15 improved pastures 0.05 mangrove swamp 0.20 medium density under construction 0.10 mixed rangeland 0.06 mixed shrubs 0.10 mixed units fixed and mobile home units 0.12 mixed wetland hardwoods 0.14 mobile home units 0.12 multiple dwelling units low rise 0.12 natural river stream waterway 0.04 open land 0.04 ornamentals 0.06 palmetto prairies 0.15 parks and zoos 0.07 pine flatwoods 0.10 reservoirs 0.06 row crops 0.04 rural residential 0.12 saltwater marshes 0.10 saltwater ponds 0.05 spoil areas 0.05 tidal flats 0.03 tree nurseries 0.10 upland mixed coniferous hardwood 0.15 wet melaleuca 0.15 wet pinelands hydric pine 0.10 wet prairie 0.20 wetland coniferous forests 0.20 wetland forested mixed 0.15


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3.3.3 BRIDGES AND CULVERTS The model included 32 bridge and culvert openings under US41, Old Marco Trail Road and CR92. The bridges were modeled as culverts in the lateral structures tool within the RAS geometry editor. The dimensions for the US 41 bridge and culvert openings under US41 were based on the survey data collected in 2018. The dimensions for the Old Marco Trail Road culverts were based on field measurements provided by Collier Seminole State Park. The dimension for the CR92 bridge was based on plans provided by Collier Seminole State Park. Culverts were modeled using the inline structures, lateral structures and storage area connectors tools within the RAS geometry editor. Bridge and culvert data are summarized in TABLE 3.3-1 and TABLE 3.3-2. The locations of modeled culverts and bridges are shown in FIGURE 3.3.3-1 and FIGURE 3.3.3-2.

TABLE 3.3-1 BRIDGES MODELED

FDOT Bridge Number

Bridge Width (ft)

Bridge Low Chord El.

(ft NAVD88) Bridge 37 72 3.5 Bridge 39 133 2.5 Bridge 40 58 2.8 Bridge 41 58 2.7 Bridge 42 42 3.3 Bridge 43 58 2.8 Bridge 44 73 2.8 Bridge 45 58 2.7 Bridge 46 43 2.7 Bridge 47 72 2.5 Bridge 48 58 3 Bridge 49 58 2.6 Bridge 50 58 3.1 Bridge 51 58 3 Bridge 52 58 2.7 CR92 Bridge 60 3


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TABLE 3.3-2 CULVERTS MODELED

Culvert Type Quantity Size US41 Ditch Hamilton Rd Crossing Concrete Pipe 2 48 in.

Under US41 Culvert 1 Concrete Box 2 9 ft. (W) x 5 ft. (H) US41 Ditch Riggs Rd Crossing Concrete Pipe 2 42 in.

Under US41 Culvert 2 Concrete Pipe 3 42 in. US41 Ditch 6Ls Farm Road Crossing Corrugated Metal Pipe 3 48 in.

Under US41 Near 6Ls Farm Rd Concrete Pipe 3 42 in. US41 Ditch Tomato Rd Crossing Corrugated Metal Pipe 2 48 in.

Under US41 Ditch Near Tomato Rd Concrete Pipe 3 48 in. Farm Ditch Tomato Rd Crossing Corrugated Metal Pipe 2 60 in.

Indian Village Rd Crossing Corrugated HDPE 3 36 in. US41 Culvert 42a Concrete Pipe 2 36 in. US41 Culvert 46a Concrete Box 1 10 ft. (W) x 3 ft. (H) US41 Culvert 51a Concrete Pipe 3 36 in.

Old Marco Trail Culvert 1 Corrugated Metal Pipe 1 36 in. Old Marco Trail Culvert 2 Corrugated Metal Pipe 2 30 in. Old Marco Trail Culvert 3 Corrugated Metal Pipe 3 18 in.

FIGURE 3.3.3-1 LOCATIONS OF MODELED CULVERTS


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FIGURE 3.3.3-2 LOCATIONS OF MODELED CULVERTS AND BRIDGES

3.3.4 INLINE STRUCTURES Inline structures are located in 1D canal reaches and includes culverts in the US41 ditch and the central farm ditch. Culvert information for these areas were collected from the 2018 survey. 3.3.5 LATERAL STRUCTURES Lateral structures in the model are located along 1D canal reaches and connect to 2D areas. Interflow between the 1D reach and 2D area is computed using the weir equation within HEC-RAS. There are a total of 11 lateral structures defined in the model. Lateral structures were used to model the banks for the farm ditches and US41 ditch. The lateral structures elevations were cut from the DEM. Several lateral structure include culverts and bridges. TABLE 3.3-3 summarizes the lateral structures in the model. The lateral structure representing US41 (right bank of US41 ditch) includes bridges and culverts. FIGURE 3.3.5-1 shows lateral structure 27000 representing US41 in the model.


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TABLE 3.3-3 LATERAL STRUCTURES IN MODEL

Lateral Structure 1D River Reach Lateral Structure Function

27500 East Farm Ditch Left Bank Connects East Farm Ditch to 2D Area Representing Picayune Forest 16000 East Farm Ditch Left Bank Connects East Farm Ditch to 2D Area Representing Picayune Forest 6500 East Farm Ditch Left Bank Connects East Farm Ditch to 2D Area Representing Picayune Forest 48000 US41 Ditch Right Bank Connects US41 Ditch to 2D Area South of US41 43150 US41 Ditch Right Bank Connects US41 Ditch to 2D Area South of US41 37100 US41 Ditch Left Bank Connects US41 Ditch to 2D Area Representing Picayune Forest 37000 US41 Ditch Right Bank Connects US41 Ditch to 2D Area South of US41 27200 US41 Ditch Left Bank Connects US41 Ditch to 2D Area Representing Picayune Forest 27000 US41 Ditch Right Bank Connects US41 Ditch to 2D Area South of US41 14220 US41 Ditch Left Bank Connects US41 Ditch to 2D Area Representing Picayune Forest 14000 US41 Ditch Right Bank Connects US41 Ditch to 2D Area South of US41

FIGURE 3.3.5-1 US41 MODELED AS LATERAL STRUCTURE

3.3.6 2D AREAS 2D areas were used to model the Picayune Forest and the area south of US41. Unsteady-flow routing used the Diffusion Wave equations. The 2D areas are shown in FIGURE 3.3.6-1. The model mesh was refined using breaklines for levees, roads and other topographic features requiring smaller cell sizes. TABLE 3.3-4 summarizes the cell spacing for the 2D areas.


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FIGURE 3.3.6-1 HEC-RAS MODEL 2D AREAS

TABLE 3.3-4 2D AREAS CELL SPACING

2D Area Minimum Cell Spacing (ft)

Maximum Cell Spacing (ft)

Picayune 50 250 SouthUS41 100 250

3.3.7 INTERNAL 2D AREA CONNECTIONS Internal 2D connections are used to model hydraulic structures within 2D areas. Old Marco Trail Road and CR92 were modeled as internal 2D connections. The Old Marco Trail Road culverts are described in TABLE 3.3-2. The CR92 bridge is described in TABLE 3.3-1 For the with project condition the SWPF levee and levee access road were modeled as internal 2D connections. 3.3.8 BOUNDARY CONDITIONS The HEC-RAS Combined 1D/2D Model has upstream, downstream and internal boundary conditions. The boundary conditions for the 1D and 2D models are described in the following sections.


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3.3.8.1 1D BOUNDARY CONDITIONS Boundary conditions for the 1D reaches were estimated based on the drainage discharges from the three farm permits. The methodology for estimating the farm drainage discharges were based on discussions between the USACE and consultants for Lipman Farms. The drainage discharges were computed based on rainfall on each permitted farm parcel and the volume of groundwater pumped down to 15 inches below land surface. The discharges were capped at the regulatory limit for each permit. The regulatory limits for the three farm permits are shown in TABLE 3.3-5. The discharge locations into the HEC-RAS 1D reaches are shown in FIGURE 3.3.8-1 and summarized in TABLE 3.3-6. FIGURE 3.3.8-2 through FIGURE 3.3.8-4 shows how the computed flows were capped to the regulatory limit for input into the RAS model. The regulatory limit for Permit 11-00076-S was a point of contention with Lipman Farms. The farm representatives contend that the limit should be 770 cfs which is the total discharge for all the permitted pumps onsite. The total capacity of the offsite discharge pumps is actually 540 cfs. The decision was made by the PDT to design the SWPF based on the regulatory limit of 173 cfs for Permit 11-00076-S. Some sensitivity runs were made to assess the levels in the farm drainage ditches when the flow cap was increased to 540 cfs and 770 cfs.

TABLE 3.3-5 PERMITTED DRAINAGE DISCHARGE FOR FARM

Permit No. Permitee Regulatory Limit

070314-9 Deseret 71 cfs 11-00097-S Lipman 135 cfs 11-00076-S Lipman 173 cfs

TABLE 3.3-6 SUMMARY OF HEC-RAS 1D BOUNDARY CONDITIONS

Boundary Condition Farm Permit Discharge Location

BC1 070314-9 East Farm Ditch BC2 11-00097 East Farm Ditch BC3 11-00097 Central Farm Ditch BC4 11-00076 East Farm Ditch BC5 11-00076 US41 Ditch BC6 11-00076 US41 Ditch


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FIGURE 3.3.8-1 HEC-RAS 1D INFLOW BOUNDARY CONDITIONS


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FIGURE 3.3.8-2 DESERET PERMIT 070314-9 FLOW CAP

FIGURE 3.3.8-3 LIPMAN PERMIT 11-00097 FLOW CAP


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FIGURE 3.3.8-4 LIPMAN PERMIT 11-00076 FLOW CAP

3.3.8.2 2D BOUNDARY CONDITIONS Boundary conditions for the HEC-RAS 2D areas were based on the data extracted from the GSHHA flood event model. For the 2D area called Picayune, stage boundary conditions were applied to the north and east. A stage boundary condition was applied to the south of the 2D area called SouthUS41. The stage boundary conditions were broken up into multiple segments to ensure an accurate representation of the GSHHA data. Precipitation was also applied temporally to the 2D areas. The north and east stage boundary conditions are shown in FIGURE 3.3.8-5, FIGURE 3.3.8-5 and FIGURE 3.3.8-6. Figure 3.3.8-7 shows how the boundary conditions were applied to the 2D areas. The higher elevations for the with project conditions are due to the restoration flows associated with PSRP. The south stage boundary condition was the same for both the with and without condition. The south stage boundary condition is shown in FIGURE 3.3.8-8.


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FIGURE 3.3.8-5 NORTH STAGE BOUNDARY CONDITION FOR WITH AND WITHOUT PROJECT (25 YR

STORM)

FIGURE 3.3.8-6 EAST STAGE BOUNDARY CONDITION FOR WITH AND WITHOUT PROJECT (25 YR

STORM)


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Figure 3.3.8-7 HEC-RAS 2D MODEL BOUNDARY CONDITIONS

FIGURE 3.3.8-8 SOUTH STAGE BOUNDARY CONDITION FOR WITH AND WITHOUT PROJECT (25 YR

STORM)


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4. HYDRAULIC DESIGN SWPF 4.1 SWPF DESIGN OVERVIEW The proposed SWPF design consists of the following:

- Approximately 7.5 mile levee that runs along the eastern perimeter of the 6Ls Farm area. - A conveyance canal that runs parallel to the levee. The conveyance canal has a bottom width of

20 feet and an average depth of 4 feet. - US41 culvert structure located near the existing TAMIATOM culvert. This structure will consist of

three (3) 12 ft (wide) x 4 ft (high) concrete box culverts that are spaced 120 feet apart. - A flap gated culvert located near the southern end of the levee. This structure consists of two (2)

5 ft diameter concrete pipes. - CR92 culvert structure. This structure will consist of one (1) 10 ft (wide) x 3 ft (high) concrete box

culvert. - Addition of an additional culvert pipe at the existing Indian Road crossing over the US41 ditch. - Levee access road that is an extension from the existing Tomato Road onsite. - Levee access road culverts. The east farm ditch and conveyance canal crossings each will have

three (3) 5 ft. diameter concrete culvert pipes. The SWPF design is shown conceptually in FIGURE 3.3.8-1.


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FIGURE 3.3.8-1 SWPF DESIGN FEATURES


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4.2 PROTECTION LEVEE The original proposed levee design from the PIR had the levee tying in with US41 to the south. The GSHHA Modeling showed that the levee would need to be gapped at the southern end to prevent backwater effects that could impact the existing farm drainage capacity. The RAS model determined that an approximately 1,200 feet gap would be adequate.

FIGURE 3.3.8-1 LEVEE GAP LOCATION

The levee elevation was set to have a minimum of 2.5 feet superiority over the 100-year maximum computed water surface profile. The levee profile is shown in FIGURE 3.3.8-2 and summarized in TABLE 4.2-1.


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FIGURE 3.3.8-2 SWPF LEVEE PROFILE

TABLE 4.2-1 LEVEE SUMMARY TABLE

Station Water El. (ft NAVD88)

Levee El. (ft NAVD88)

Superiority (ft)

1000.6 8.8 11.5 2.7 12940.4 8.4 11.0 2.6 17263.2 7.9 10.5 2.6 25279.6 6.8 9.5 2.7 31181.8 5.3 8.0 2.7 38737.7 4.7 7.5 2.7


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4.3 CONVEYANCE CANAL The conveyance canal was designed to capture overflow from the east farm ditch and efficiently convey the water to the south and out into the Picayune Forest approximately 1,000 feet from US41. This canal will also collect seepage from the increased water levels from the PSRP forest. Maximum flowrates in the conveyance canal range from approximately 95 to 120 cfs for the 5 year through 100 year storm events. Average velocities in the canal during peak discharge is less than 1 fps. FIGURE 3.3.8-1 shows maximum computed water profiles in the conveyance canal for the 5 through 100 year storm events. FIGURE 3.3.8-2 shows the conveyance canal burned into the with project DEM. FIGURE 3.3.8-3 shows a cross section of the east farm ditch and proposed conveyance canal.

FIGURE 3.3.8-1 CONVEYANCE CANAL MAXIMUM COMPUTED WATER PROFILE FOR 5, 10, 25 AND 100

YR STORMS


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FIGURE 3.3.8-2 DEM WITH CONVEYANCE CANAL BURNED IN

FIGURE 3.3.8-3 CROSS SECTION OF EAST FARM DITCH AND PROPOSED CONVEYANCE CANAL


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4.4 CONVEYANCE STRUCTURES The proposed conveyance structures were optimized to move water to the south and southeast. The levee culvert is a flap gated culvert structure that discharges into the Picayune Forest approximately 1 mile north of US41. The design discharge for the levee culvert is 110 cfs with 0.3 ft of head. This structure consists of two 5 ft diameter concrete pipes. The US41 culvert structure is located near the US41 Tomato Road crossing. This structure has a design flowrate of 200 cfs with 0.1 ft of head. This structure consists of three 12 ft wide by 4 ft high concrete box culverts. The culverts are spaced 120 ft apart. Culverts are also required at the levee access road crossing over the existing east farm ditch and proposed conveyance canal. Each canal crossing will have three 5 ft diameter concrete culverts. These culverts each have a design capacity of 110 cfs with 0.1 ft of head. The locations for these conveyance features are shown in FIGURE 3.3.8-1. With project flow vectors near 6Ls Farm are shown in FIGURE 3.3.8-2.

FIGURE 3.3.8-1 PROPOSED CULVERT LOCATIONS NEAR 6LS FARM


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FIGURE 3.3.8-2 WITH PROJECT CONDITION FLOW VECTORS DOWNSTREAM 6LS FARM

The modified Indian Village Road culvert and CR92 culvert structure further augment the conveyance of water to the south and southeast. The existing Indian Village Road culvert consists of three 3 ft diameter corrugated HDPE pipes. The with project condition adds one additional culvert pipe to this existing structure. The design flowrate for this structure is 95 cfs with 0.3 ft of head. The CR92 culvert is located downstream from Bridge 37. This structure will reconnect a historic drainage channel that was cut with the construction of CR92. The design flowrate for this structure is 100 cfs with 0.4 ft head. The locations for these proposed structures are shown in FIGURE 3.3.8-3. Flow vectors for the with project conditions near CR92 are shown in FIGURE 3.3.8-4.


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FIGURE 3.3.8-3 PROPOSED CULVERT LOCATIONS NEAR CR92

FIGURE 3.3.8-4 WITH PROJECT CONDITION FLOW VECTORS NEAR CR92


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5. RESULTS OF HYDRAULIC ANALYSIS The with and without project conditions were simulated for the 5-, 10- 25- and 100-year storm events. All these events were simulated at a 5-day duration because it has been documented (SFWMD EMA #390) that the volume of rainfall at this duration is generally larger than a 1- or 3-day durations. The elevations in the east and central farm ditches for the project conditions were equal to or lower than for the without project condition. 5.1 5-YEAR STORM EVENT SIMULATION The results for the 5-year simulations are discussed in the following sections. 5.1.1 CANAL WATER ELEVATIONS The elevations in the three main drainage canals were compared for the with and without project conditions. Maximum computed canal elevations for the with and without project conditions are shown in FIGURE 5.1.1-1 through FIGURE 5.1.1-3.

FIGURE 5.1.1-1 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATION FOR WITH AND

WITHOUT PROJECT (5 YR STORM EVENT)


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FIGURE 5.1.1-2 CENTRAL FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND

WITHOUT PROJECT (5 YR STORM EVENT)

FIGURE 5.1.1-3 US41 DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND WITHOUT

PROJECT (5 YR STORM EVENT)


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5.1.2 BRIDGE AND CULVERT FLOWS The computed flows through existing bridges 37, 39, 45, and the Indian Village culverts were compared for the with and without project. Comparison of flows through existing structures are shown in FIGURE 5.1.2-1 through FIGURE 5.1.2-4. The computed flows for the new proposed US41 culvert structure and CR92 culvert structure are shown in FIGURE 5.1.2-5 and FIGURE 5.1.2-6.

FIGURE 5.1.2-1 BRIDGE 37 COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT (5 YR STORM)


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’

FIGURE 5.1.2-4 INDIAN VILLAGE RD CULVERT COMPUTED FLOWS WITH AND WITHOUT PROJECT (5 YR

STORM)

FIGURE 5.1.2-5 PROPOSED US41 CULVERT COMPUTED FLOWS (5 YR STORM)


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FIGURE 5.1.2-6 PROPOSED CR92 CULVERT COMPUTED FLOWS (5 YR STORM)

5.2 10-YEAR STORM SIMULATIONS The results for the 10-year simulations are discussed in the following sections. 5.2.1 CANAL WATER ELEVATIONS The elevations in the three main drainage canals were compared for the with and without project conditions. Maximum computed canal elevations for the with and without project conditions are shown in Figure 5.2.1-1 through FIGURE 5.2.1-3.


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Figure 5.2.1-1 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND

WITHOUT PROJECT (10 YR STORM)

FIGURE 5.2.1-2 CENTRAL FARM DITCH MAXIMUM COMPUTED FLOWS FOR WITH AND WITHOUT

PROJECT (10 YR STORM)


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FIGURE 5.2.2-4 INDIAN VILLAGE RD CULVERT COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT

(10 YR STORM)


Page 41




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5.2.3 10-YEAR STORM SIMULATIONS WITH FLOW CAP INCREASE Additional simulations were performed with the outflow for Farm Permit 11-00076 capped at 540 cfs and 770 cfs (FIGURE 5.3.3-1 through FIGURE 5.3.3-4).

FIGURE 5.2.3-1 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATIONS FOR WITH AND

WITHOUT PROJECT (10 YR STORM FLOW CAPPED AT 540 CFS)


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5.3 25-YEAR STORM SIMULATIONS The results for the 25-year simulations are discussed in the following sections. 5.3.1 CANAL WATER ELEVATIONS The elevations in the three main drainage canals were compared for the with and without project conditions. Maximum computed canal elevations for the with and without project conditions are shown in FIGURE 5.3.1-1 through FIGURE 5.3.1-3.


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FIGURE 5.3.2-4 INDIAN VILLAGE RD CULVERTS COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT

(25 YR STORM)


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5.3.3 25-YEAR STORM SIMULATIONS WITH FLOW CAP INCREASE Additional simulations were performed with the outflow for Farm Permit 11-00076 capped at 540 cfs and 770 cfs (FIGURE 5.3.3-1 through FIGURE 5.3.3-4).




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WITHOUT PROJECT (25 YR FLOW CAPPED AT 540 CFS)

FIGURE 5.3.3-3 EAST FARM DITCH MAXIMUM COMPUTED WATER ELEVATION FOR WITH AND

WITHOUT PROJECT (25 YR STORM FLOW CAPPED 770 CFS)


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5.4 100-YEAR STORM SIMULATIONS The results for the 100-year simulations are discussed in the following sections.

5.4.1 CANAL WATER ELEVATIONS The elevations in the three main drainage canals were compared for the with and without project conditions. Maximum computed canal elevations for the with and without project conditions are shown in FIGURE 5.4.1-1 through FIGURE 5.4.1-3.


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WITHOUT PROJECT CONDITIONS (100 YR STORM)


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PROJECT CONDITIONS (100 YR STORM)



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FIGURE 5.4.2-4 INDIAN VILLAGE RD CULVERTS COMPUTED FLOWS FOR WITH AND WITHOUT PROJECT

(100 YR STORM)


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6. DISCUSSION OF RESULTS The hydraulic modeling demonstrates that implementation of the PSRP with the SWPF in-place results in no adverse impacts to the flood protection for the 6Ls Farm. The elevations in the east and central farm ditches for the project conditions were equal to or lower than for the without project condition. When the flow cap for Permit 11-00076 was increased to 540 cfs there was a maximum increase of approximately 0.2 feet in the east farm ditch and minimal difference in the central farm ditch. When the flow cap was increased to 770 cfs there was a maximum increase of 0.4 feet in the east farm ditch and minimal difference in the central farm ditch. The US41 bridge flows were higher for the project condition compared to the without project condition. This is to be expected due to the restoration flows associated with PSRP.


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7. REFERENCES HEC-RAS River Analysis System, 2D Modeling User’s Manual, February 2016, CPD-68A, U.S. Army Corps of Engineers, Davis, CA. HEC-RAS River Analysis System, Hydraulic Reference Manual, Hydrologic Engineering Center, November 2002, U.S. Army Corps of Engineers, Davis, CA. HEC-RAS River Analysis System, User’s Manual, November 2006, Hydrologic Engineering Center, U.S. Army Corps of Engineers, Davis, CA. 2004 PSRP PIR EIS 2016 PSRP LRR EA SFWMD (2001) Technical Publication EMA #390. Frequency Analysis of Daily Rainfall Maxima for Central and South Florida


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8. LIST OF ABBREVIATIONS 1D one-dimensional 2D two-dimensional a.k.a. also known as acft acre-feet BC Boundary Condition CR County Road ft feet GIS Geographical Information System HEC-RAS Hydrologic Engineering Center - River Analysis System Hwy Highway LIDAR Light Detection and Ranging NAD North American Datum NAVD88 North American Vertical Datum of 1988 PIR Project Implementation Report Rd Road SFWMD South Florida Water Management District SOP Standard Operating Procedures USACE United States Army Corps of Engineers USCS Unified Soil Classification System USGS United States Geological Survey

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