Final Location Hydraulic Report June 2009

FINAL LOCATION HYDRAULIC REPORT

Anna Maria Island Bridge Project Development and Environment Study

SR 64 (Manatee Avenue) From SR 789 (East Bay Drive) to Perico Bay Boulevard Manatee County, Florida

Financial Project ID: 424436-1-21-01

Prepared for:

Florida Department of Transportation District Environmental Management Office 801 North Broadway P.O. Box 1249 Bartow, FL 33831

June 2009 FINAL LOCATION HYDRAULIC REPORT

Anna Maria Island Bridge Project Development and Environment Study

SR 64 (Manatee Avenue) From SR 789 (East Bay Drive) to Perico Bay Boulevard Manatee County, Florida

Financial Project ID: 424436-1-21-01

Prepared for:

Florida Department of Transportation District Environmental Management Office 801 North Broadway P.O. Box 1249 Bartow, FL 33831

Prepared by:

482 S. Keller Road Orlando, Florida 32810

June 2009 EXECUTIVE SUMMARY

The Florida Department of Transportation (FDOT) is conducting a Project Development and Environment (PD&E) Study for improvement alternatives along SR 64 (Manatee Avenue), from west of SR 789 (East Bay Drive) to east of Perico Bay Boulevard in Manatee County, Florida.

The Anna Maria Island Bridge, constructed in 1957, is one of three bridge facilities that provide vehicular access over Anna Maria Island Sound/Gulf Intracoastal Waterway to and from Anna Maria Island. The PD&E Study evaluates alternatives to address the problem of the deteriorating bascule bridge on SR 64 (Manatee Avenue), the most northerly access, which is a designated evacuation route.

Bridge inspection reports have shown that the Anna Maria Island Bridge is functionally obsolete. The structural condition is anticipated to deteriorate further as the bridge surpasses its service life of 50 years. Substandard geometry such as the lack of shoulders, 9-inch (in) wide concrete curbs separating the travel lanes from the sidewalk and obsolete bridge railing contribute to the functional obsolescence of the existing structure. Viable improvement alternatives considered for this facility include rehabilitation and replacement of the current bridge. The development of a new corridor would result in significant social and environmental impacts, and would not address the problem of the deteriorating SR 64 (Manatee Avenue) bridge. Therefore, developing a new corridor or improving a parallel roadway is not an option for this project.

Three general bridge replacement alternatives were evaluated for this PD&E Study:

• Alternative 1 − Low-Level Bascule: This concept proposes building a new bascule bridge with a minimum vertical navigational clearance of 21 feet (ft) above mean high water (MHW) when the bascule leaves are lowered. This is the established vertical guide clearance set by the USCG. • Alternative 2 − Mid-Level Bascule: This concept proposes a replacement bascule bridge with a navigation clearance of 45 ft. Based on data provided by the bridge tender at Anna Maria Island Bridge and allowing for tidal fluctuations, this height would allow approximately 39 percent of the waterway users that currently require the bridge to open to pass without an opening. • Alternative 3 – High-Level Fixed-Span: This concept proposes a high-level fixed-span replacement bridge over the existing Gulf Intracoastal Waterway navigation channel. The vertical navigational clearance will be 65 ft. Based on data provided by the bridge tender at the Anna Maria Island Bridge and allowing for tidal fluctuations, this height would allow greater than 99 percent of boats that currently require the existing bridge to open to safely navigate under the proposed structure.

A tunnel was also evaluated but found to be non-viable.

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report i Bridge replacement alignment alternatives to the left, center and right (north, center and south) of the existing bridge were considered. A centered alignment would conflict with the existing bridge, and traffic could not be maintained on the existing bridge during construction. Therefore, the centered alignment was eliminated from further consideration.

The combination of three bridge types and two alignments (northern and southern) result in six viable bridge replacement alternatives. Additionally, two proposed two-lane undivided bridge typical sections are being considered for all of the bridge replacement alternatives in this study. Both typical sections include two 12-ft lanes and two 10-ft shoulders which can accommodate bicyclists and disabled vehicles.

Typical Section A includes one 12-ft sidewalk along the north side of the bridge, separated from the shoulder by a concrete barrier wall. A 4.5-ft high pedestrian/bicycle railing will be provided on the outside of the 12-ft sidewalk. There will be no sidewalk on the south side.

Typical Section B includes a 10-ft sidewalk along both the north and south sides of the bridge. The designations “A” and “B” have been added to the alternative names accordingly.

All of the bridge replacement alternatives are within the coastal floodplain and are subject to flooding to some degree due to tidal storm surges. All bridge replacement alternatives will have some minor impact to the floodplain but flood elevations and risks will not be increased due to the changes in vertical or horizontal alignments presented in this study.

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report ii TABLE OF CONTENTS

Section Title Page

EXECUTIVE SUMMARY ...... i

TABLE OF CONTENTS...... iii

LIST OF FIGURES ...... v

1.0 INTRODUCTION ...... 1-1 1.1 Purpose...... 1-1 1.2 Project Description...... 1-1 1.3 Project Need...... 1-3

2.0 ALTERNATIVES CONSIDERED...... 2-1 2.1 Corridor Analysis...... 2-1 2.2 No-Build Alternative...... 2-1 2.3 Transportation Systems Management Alternative...... 2-1 2.4 Rehabilitation Alternative...... 2-2 2.5 Bridge Replacement Alternatives ...... 2-2 2.5.1 Typical Sections...... 2-2 2.5.2 Horizontal Alignments...... 2-5 2.5.3 South Alternative...... 2-5 2.5.4 North Alternative...... 2-5 2.5.5 Bridge Type...... 2-8 2.6 Proposed Bridge Replacement Alternatives ...... 2-11 2.6.1 Alternative 1BN – Low-Level Bascule, Typical Section B, North Alignment ...... 2-11 2.6.2 Alternative 1BS – Low-Level Bascule, Typical Section B, South Alignment ...... 2-13 2.6.3 Alternative 2BN – Mid-Level Bascule, Typical Section B, North Alignment ...... 2-14 2.6.4 Alternative 2BS – Mid-Level Bascule, Typical Section B, South Alignment ...... 2-15 2.6.5 Alternative 3BN – High-Level Fixed-Bridge, Typical Section B, North Alignment ...... 2-16 2.6.6 Alternative 3BS – High-Level Fixed-Bridge, Typical Section B, South Alignment ...... 2-17

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report iii P:\Projects\FDOT\D1\Anna_Maria_Bridge\Reports\LHR\Final LHR\Final for Production\FINAL_LHR_June2009.doc TABLE OF CONTENTS (CONT.)

Section Title Page

3.0 ANALYSIS OF FLOODPLAIN IMPACTS ...... 3-1 3.1 Project Setting and Land Use...... 3-1 3.2 National Flood Insurance Program Communities...... 3-1 3.3 Floodplains...... 3-6 3.3.1 Floodplain Impacts Mid and Low-Level Alternatives...... 3-6 3.3.2 Floodplain Impacts High-Level Alternative ...... 3-6 3.3.3 Other Cross Drains...... 3-10 3.3.4 Stormwater Management Facilities ...... 3-10

4.0 STUDY REQUIREMENTS...... 4-1 4.1 Discussion...... 4-1 4.2 Items to be Addressed...... 4-1 4.2.1 Items Regarding Floodplain Fill Encroachment...... 4-1 4.2.2 Items Regarding Projects with Bridges...... 4-4

5.0 FLOODPLAIN COORDINATION...... 5-1 5.1 Manatee County...... 5-1 5.2 City of Holmes Beach...... 5-1 5.3 City of Bradenton...... 5-1 5.4 Southwest Florida Water Management District...... 5-1

6.0 CONCLUSIONS...... 6-1 6.1 Conclusions...... 6-1

7.0 REFERENCES ...... 7-1

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report iv LIST OF FIGURES

Figure Number Title Page

1-1 Project Location Map...... 1-2

2-1 Proposed Bridge, Rehabilitation Typical Sections ...... 2-3 2-2 Proposed Bridge, Typical Section A...... 2-4 2-3 Proposed Bridge, Typical Section B...... 2-6 2-4 South Alignment ...... 2-7 2-5 North Alignment ...... 2-9 2-6 Profile Comparison ...... 2-10 2-7 Proposed Roadway, Typical Section B...... 2-12

3-1 Project Location: Water Depths and Navigational Aids...... 3-2 3-2 Project Location Relative to Longboat Pass and Big Sarasota Bay...... 3-3 3-3 Project Location Relative to New Pass and Big Sarasota Pass...... 3-4 3-4 Project Location Relative to Gulf of Mexico and Tampa Bay ...... 3-5 3-5a Flood Insurance Rate Map...... 3-7 3-5b Flood Insurance Rate Map...... 3-8 3-5c Flood Insurance Rate Map...... 3-9

4-1a Soil Boring Locations (from 1998 PDE) ...... 4-5 4-1b Soil Boring Profiles (from 1998 PDE)...... 4-6 4-2 Inspection Profiles ...... 4-7

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report v SECTION 1.0 INTRODUCTION

The Florida Department of Transportation (FDOT) is conducting a Project Development and Environment (PD&E) Study to evaluate improvement alternatives for the Anna Maria Bridge over the Gulf Intracoastal Waterway. The PD&E Study limits encompass the portion of SR 64 (Manatee Avenue) from west of SR 789 (East Bay Drive) to east of Perico Bay Boulevard in Manatee County, Florida. The project location map (Figure 1-1) illustrates the location and limits of the PD&E Study. 1.1 PURPOSE

The purpose of the PD&E Study is to provide documented environmental and engineering analyses to assist FDOT and the United States Coast Guard (USCG) in reaching a decision on the type, location and conceptual design of the necessary improvements, in order to accommodate future traffic demand in a safe and efficient manner. The PD&E Study also satisfies the requirements of the National Environmental Policy Act (NEPA) and other related state and federal environmental laws and regulations in order to qualify the project for federal-aid funding of future development phases of the project.

This PD&E Study documents the need for the roadway and bridge improvements, and presents the procedures utilized to develop and evaluate various improvement alternatives. Information relating to the engineering and environmental characteristics essential for development of alternatives and analytical decisions is being collected. Design criteria have been established and preliminary alternatives have been developed. The comparison of alternatives is based on a variety of parameters utilizing a matrix format. This process identifies the alternative which would minimize natural, physical, and socio-economic impacts, while providing the necessary improvements. The study also solicits input from the community and users of the facility. The design year for the analysis is 2030.

The purpose of this Location Hydraulic Report (LHR) is to document floodplain impacts anticipated by each of the alternatives, and to determine the significance of those impacts. 1.2 PROJECT DESCRIPTION

The PD&E Study limits encompass the portion of SR 64 (Manatee Avenue) from west of SR 789 (East Bay Drive) at milepost (MP) 0.216 in the City of Holmes Beach on Anna Maria Island to east of Perico Bay Boulevard at MP 2.152 in the City of Bradenton, a distance of 1.936 miles (mi). The project is located within Sections 27 and 28, Township 34 South, Range 16 East, and within the Bradenton Beach United States Geological Survey (USGS) quad map. The Anna Maria Island Bridge is a low-level bascule structure (Bridge Number 130054) that spans the Gulf Intracoastal Waterway, a marked federal navigational channel which generally runs between the mainland and the nearly contiguous barrier islands along the Gulf of Mexico. SR 64 (Manatee Avenue) is not part of the National Highway System (NHS), the Florida Intrastate Highway

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 1-1

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 1-2 System (FIHS), or the Strategic Intermodal System (SIS); however, the Gulf Intracoastal Waterway within the PD&E Study area is on the SIS. In addition, both SR 64 (Manatee Avenue) and SR 789 (East Bay Drive) are designated evacuation routes by the Florida State Emergency Response Team (SERT). SR 64 (Manatee Avenue) from SR 789 (East Bay Drive) to 75th Street West is also designated as the Palma Sola Scenic Highway.

SR 64 (Manatee Avenue) was originally constructed in 1957 to connect Anna Maria Island with the mainland in Manatee County. SR 64 (Manatee Avenue) is an east-west minor urban arterial that provides one of three vehicular access routes to Anna Maria Island. 1.3 PROJECT NEED

Recent bridge inspection reports list the bridge as containing fracture critical components and functionally obsolete. The bridge is not rated structurally deficient or scour critical; however, the bridge deck is susceptible to damage due to wave action during a severe storm. The deck, superstructure, and substructure are all rated fair, with an overall sufficiency rating of 36.7. A rehabilitation project was completed in 2009 and the sufficiency ratings are expected to improve. Substandard geometry such as the lack of shoulders, 9-inch (in) wide concrete curbs separating the travel lanes from the sidewalk, and obsolete bridge railing contribute to the functional obsolescence of the existing structure. Due to the naturally corrosive environment, the substructure and superstructure of the Anna Maria Island Bridge have degraded and are undergoing extensive rehabilitation that is expected to allow for another 10-15 years of service. However, these elements will need further repair in the near future as the structure ages beyond its service life of 50 years. Further degradation of the existing structure will result in a lower sufficiency rating that may eventually require it to be replaced. According to the Federal Highway Administration (FHWA), a bridge receiving a sufficiency rating below 50.0 is considered to be a candidate for replacement funding. Based on the above stated sufficiency rating of 36.7, it is clear that the existing Anna Maria Island Bridge will be soon in need of repair or replacement.

The purpose of this project is to solely address the structural deficiencies of the existing bridge. Additional capacity or access control improvements are not proposed as part of this project.

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 1-3 SECTION 2.0 ALTERNATIVES CONSIDERED

The objective of the alternative analysis process is to identify technically and environmentally sound alternatives that safely accommodate the design year 2030 traffic projections, that are acceptable to the community, and that are cost effective. The process will result in the selection of a Preferred Alternative which can be advanced to the design phase. This section summarizes the viable alternatives evaluated in the Project Development and Environment (PD&E) Study for the SR 64 (Manatee Avenue) bridge over the Intracoastal Waterway. For more information, refer to the Project Development Summary Report (PDSR). 2.1 CORRIDOR ANALYSIS

SR 64 (Manatee Avenue) is one of two facilities that provide vehicular access across Anna Maria Sound and over the Gulf Intracoastal Waterway between Bradenton and Anna Maria Island. A third bridge connects Anna Maria Island to Longboat Key to the south. The development of a new corridor would result in significant social and environmental impacts and would not address the problem of the deteriorating SR 64 (Manatee Avenue) bridge, which is a designated evacuation route. Therefore, developing a new corridor or improving a parallel roadway is not an option for this project. Rehabilitation or replacement of the current bridge within the existing corridor provides for the most feasible solution. Alternatives to the left, center and right (north, center and south) of the existing bridge will be evaluated to identify a preferred alignment for the bridge Build Alternatives within the existing corridor. 2.2 NO-BUILD ALTERNATIVE

The No-Build Alternative consists of continuing the normal maintenance and repair of the existing bridge in its current configuration while keeping the bridge operating in a safe condition and maintaining the existing typical sections. This alternative includes installing cathodic protection pile jackets (structural and non-structural), repairing the concrete (sealing cracks, patching spalls, etc.), repairing the fender system and repairing the bascule span steel in order to extend the service life 10 years. The No-Build Alternative does not require closure of the bridge to make the repairs. At the end of the 10-year period, a rehabilitation or replacement of the bridge would be required.

The No-Build Alternative does not require stormwater management facilities (SMF) since it does not alter the existing roadway or add additional capacity. The existing bridge will remain in its current configuration and no additional travel lanes are proposed. 2.3 TRANSPORTATION SYSTEMS MANAGEMENT ALTERNATIVE

The Transportation System Management (TSM) Alternative consists of low-cost capital improvements that maximize the efficiency of the existing system. TSM improvements include,

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 2-1 but are not limited to, improved traffic signals and intersection geometries, sidewalks, bicycle facilities, signal timing, transit improvements and improved access features. While these improvements may provide additional capacity and access control, the purpose of this project is to address the structural condition of the existing bridge. Therefore, the TSM Alternative does not meet the purpose and need of the project. However, the TSM Alternative may be implemented on an interim basis for some segments of the facility until a decision is made concerning the Preferred Alternative. 2.4 REHABILITATION ALTERNATIVE

The Rehabilitation Alternative provides the necessary rehabilitation and repair of the existing bridge to keep it operating in a safe condition and extends the service life by 25 years. The bridge’s existing design speed of 45 miles per hour (mph) and posted speed of 40 mph will remain unchanged. This alternative includes repairing the concrete, resurfacing the deck, installing cathodic protection pile jackets, installing crutch bents, repairing the fender system, repairing the electrical and mechanical systems, repairing and painting the bascule span steel, strengthening the beams using carbon fiber and other repairs to extend the service life by 25 years. In addition, the existing 9-inch (in) high brush curbs and non-crash tested bridge railings will be removed. Raised sidewalks, 5 feet (ft) wide, will be constructed behind 6-in high mountable curbs. A 32-in vertical shape traffic barrier with an aluminum bicycle bullet railing will be constructed at the back of sidewalk as shown in Figure 2-1. Another rehabilitation program or a replacement of the bridge would be required at the end of the 25-year period.

The Rehabilitation Alternative does not require SMF since it involves an alteration of the existing roadway without adding additional capacity. The existing bridge will remain in its existing configuration and no additional travel lanes are proposed.

The No-Build Alternative will remain under consideration throughout the alternatives analysis and evaluation process. 2.5 BRIDGE REPLACEMENT ALTERNATIVES

2.5.1 TYPICAL SECTIONS

Since this project is not intended to increase capacity, only two-lane typical sections were considered. Two different two-lane undivided bridge typical sections are being considered. Both typical sections include two 12-ft travel lanes and two 10-ft shoulders, which can accommodate bicyclists and disabled vehicles. The design speed for all proposed typical sections is 45 mph with a posted speed of 40 mph. The difference between the typical sections is the sidewalk configurations.

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 2-2

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 2-3

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 2-4 Typical Section B includes a 10-ft sidewalk along both the north and south sides of the bridge. Typical Section B is shown in Figure 2-3 for the fixed and bascule bridge.

2.5.2 HORIZONTAL ALIGNMENTS

A center horizontal alignment is one that follows the same alignment as the existing bridge and roadway; this alignment would require that traffic is either detoured for bridge and roadway demolition and construction or traffic is maintained on an expensive temporary bridge. Because SR 64 (Manatee Avenue) is a designated evacuation route, a prolonged detour is not feasible. Therefore, the centered alignment was eliminated from further consideration. Only north and south alignments that allow for bridge construction, transfer of traffic to the new bridge and then demolition of the old bridge, were considered.

2.5.3 SOUTH ALTERNATIVE

Any alternative on the southern alignment would allow a 14-ft separation between the old and new bridge structures. This separation provides room for construction and demolition activities to occur without disrupting traffic on the existing bridge, while avoiding impacts to the existing bridge tender house on the south side of the existing bridge. There is sufficient existing right-of-way (ROW) to construct a new bridge on a south alignment without conflicting with the existing bridge, the boat ramp, or the navigational channel north of the existing bridge. However, some ROW will be required on the south side of the roadway, east of the bridge where the ROW narrows from 1000 ft to 190 ft, impacting the Neal Preserve and sovereign submerged land. The new bridge would tie into the existing roadway using gentle, normal crown curves to the west and east of the bridge. As with the north alignment, there will be a spill-through abutment with a 1:2 slope and rubble riprap protection for all alternatives. Impacts to the mangroves and seagrasses will be greater than with a northern alignment. Additionally, negative impacts to the Kingfish Boat Ramp and impacts to the navigation channel on the north side will be avoided. Traffic operation at the boat ramp would be enhanced through increased storage capacity in the boat ramp driveways. A water main is attached to the south side of the fixed portion of the existing bridge, but is buried as it crosses the Gulf Intracoastal Waterway. Since the water main is attached to the existing bridge, it will require relocation regardless of which alignment is chosen. The water main is the only utility located on the south side. See Figure 2-4 for depiction of the south alignment.

2.5.4 NORTH ALTERNATIVE

Alternatives on a northern alignment would allow a 10-ft separation between the old and new bridge structures. This separation provides room for construction and demolition activities to occur without disrupting traffic on the existing bridge. In accordance with the FDOT Drainage Manual, section 4.9.3.2, the minimum abutment protection of spill-through abutments with a 1:2 slope and bank-and-shore rubble riprap with a horizontal blanket from the toe is assumed for all alternatives. There are currently two navigational channels immediately adjacent to the existing bridge along the northern side which provides access to the Kingfish Boat Ramp to the west and a marina to the east. A new bridge constructed to the north would impact the navigability of these channels. Therefore, dredging may be required to maintain navigable depth

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 2-5

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 2-6

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 2-7

and width. Dredging will involve other issues such as water quality as this waterway is identified as an Outstanding Florida Water (OFW), additional seagrass and mangrove impacts, possible essential fish habitat impacts, as well as United States Coast Guard (USCG) and United States Army Corps of Engineers (USACE) permit approvals. Coordination with and approval from the local sponsors of the channel, Manatee County and/or the West Coast Inland Navigation District, will also be required. A northern alignment will also impact sovereign submerged land outside the ROW on the east approach. Any realignment to the north would cause significant direct impacts to the Kingfish Boat Ramp, including: the closure of one of the three planned driveways, reduced access to the boat ramps, loss of much of the planned parking and impacts to the traffic circulation through the facility. A northern alignment would place the new construction closer to the existing potential contamination sites than a southern alignment. Existing utilities on the north side of the bridge would be impacted by the northern alignment. A water main is attached to the south side of the fixed portion of the existing bridge, but is buried as it crosses the Gulf Intracoastal Waterway. Since the water main is attached to the existing bridge, it will require relocation regardless of which alignment is chosen. See Figure 2-5 for depiction of the north alignment.

2.5.5 BRIDGE TYPE

In addition to the two horizontal alignments and two typical sections considered, three general bridge replacement alternatives were evaluated for this PD&E Study.

• Alternative 1 − Low-Level Bascule: This concept proposes building a new bascule bridge with a minimum vertical navigational clearance of 21 ft above the fenders when the bascule leaves are lowered. This is the established vertical guide clearance set by the USCG. • Alternative 2 − Mid-Level Bascule: This concept proposes a replacement bascule bridge with a navigation clearance of 45 ft. Based on data provided by the bridge tender at Anna Maria Island Bridge and allowing for tidal fluctuations, this height would allow approximately 39 percent of the waterway users that currently require the bridge to open to pass without an opening. • Alternative 3 – High-Level Fixed-Span: This concept proposes a high-level fixed-span replacement bridge over the existing Gulf Intracoastal Waterway navigation channel. The vertical navigational clearance will be 65 ft. Based on data provided by the bridge tender at the Anna Maria Island Bridge and allowing for tidal fluctuations, this height would allow greater than 99 percent of boats that currently require the existing bridge to open to safely navigate under the proposed structure.

Figure 2-6 provides a comparison of the vertical alignments, which are described in detail below.

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 2-8

Anna Maria Island Bridge PD&E Study Draft Location Hydraulic Report 2-9

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2.6 PROPOSED BRIDGE REPLACEMENT ALTERNATIVES

For the purposes of the alternatives analysis, and to keep the number of alternatives to a manageable number, all of the bridge replacement alternatives utilize the “worst case” two-lane undivided Typical Section B as shown in Figure 2-3, with two 10-ft sidewalks. Therefore, the designation “B” has been added to the alternative names accordingly. Typical Section A shown in Figure 2-2 with one 12-ft sidewalk on the north side, could be substituted and a reduced footprint would result.

Bridge replacement alternatives evaluated include:

• Alternative 1BN: Low-Level Bascule, Typical Section B, North Alignment • Alternative 1BS: Low-Level Bascule, Typical Section B, South Alignment • Alternative 2BN: Mid-Level Bascule, Typical Section B, North Alignment • Alternative 2BS: Mid-Level Bascule, Typical Section B, South Alignment • Alternative 3BN: High-Level Fixed-Bridge, Typical Section B, North Alignment • Alternative 3BS: High-Level Fixed-Bridge, Typical Section B, South Alignment

The following sections include descriptions of each bridge replacement alternative. Each description is followed by a presentation of the advantages and disadvantages of that alternative.

2.6.1 ALTERNATIVE 1BN – LOW-LEVEL BASCULE, TYPICAL SECTION B, NORTH ALIGNMENT

Alternative 1BN would replace the existing Anna Maria Island Bridge with a new low-level bascule structure similar to the existing structure, with a 21-ft vertical navigational clearance when the bridge is closed. The new structure would be built 10 ft to the north of the existing structure, utilizing Typical Section B, as shown in Figure 2-3.

Both west and east of the bridge the roadway approach maintains the existing two-lane undivided rural roadway configuration. On the west approach, a 2-ft curb-and-gutter will be added on the north side of the roadway from the beginning of construction continuing to the proposed bridge barrier wall, consistent with the proposed Kingfish Boat Ramp improvement project, additionally, the curb-and-gutter provides more area for SMF “B-N”. The remaining shoulders on each side of the proposed roadway will be 10 ft with 5 ft paved, increased from the existing 8-ft shoulders with 4 ft paved; this will bring the shoulders up to current FDOT design standards. The bridge includes a 10-ft sidewalk on both sides. The 10-ft sidewalk on the north side will transition to the existing 8-ft sidewalk. On the south side of the roadway a 10-ft sidewalk will be provided from SR 789 (East Bay Drive) to Perico Bay Boulevard. The proposed typical section of the roadway west and east of the bridge is shown in Figure 2-7. The roadway at the bridge approaches is similar except it is elevated on embankment with a 1:2 slope on each side. The 1:2 slope will have a concrete slope pavement surface and will prevent the type of erosion evident in the existing sloped embankment. The proposed roadway is consistent with the bridge typical section except that the northern sidewalk is decreased in width to 8 ft since it will be constructed by Manatee County as part of the Kingfish Boat Ramp improvements on the west and matches the existing sidewalk width on the east. Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 2-11

Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 2-12

Taking into account the mean high water (MHW) elevation of 1.09 ft, the proposed profile accommodates a minimum 21-ft vertical navigational clearance over the existing Gulf Intracoastal Waterway, similar to the existing clearance. Maximum grades of 2.8 percent are joined by a 549-ft cresting vertical curve through the bascule portion of the structure. The fixed approaches to the bascule bridge accommodate an 8-ft structure depth, except in the westernmost 226 ft and easternmost 246 ft of the bridge where the structure depth was reduced to 5 ft. This reduced structure depth was used to decrease environmental impacts by lowering the elevations of the west and east abutments which minimized the footprint of the proposed sloped abutments. The bascule span structure depth is assumed to be 10 ft. The proposed bascule bridge will be 3,596.07 ft in length, and will reach a maximum elevation of 33.31 ft in the closed position; this increase from the existing 30.00-ft elevation will allow for the 12-ft splash zone discussed earlier.

The bascule portion would consist of two bascule leaves forming a 192-ft span. As previously explained, all superstructure components would be located above the splash zone. Alternative 1BN will encroach on the existing navigational channels which run along the northern side of the existing bridge. This alternative will impede navigation which may require dredging to restore. Access from SR 64 (Manatee Avenue) to the Kingfish Boat Ramp west of the bridge will also be impacted. Three driveways currently provide access to the boat ramp and help facilitate smooth vehicle circulation with logical points of entry and exit; this alternative will require the closure of the easternmost driveway and the truncation of the center driveway. These modifications will greatly decrease the available parking and hamper vehicle circulation, as well as reduce the staging area used by vehicles for launching and retrieving watercraft. The commercial driveways east of the bridge could continue operating similar to existing conditions. As with the existing condition, the proposed bridge will not accommodate vehicular traffic under the bridge from one side of the causeway to the other.

2.6.2 ALTERNATIVE 1BS – LOW-LEVEL BASCULE, TYPICAL SECTION B, SOUTH ALIGNMENT

Alternative 1BS would replace the existing Anna Maria Island Bridge with a new low-level bascule structure similar to the existing structure, with a 21-ft vertical navigational clearance when the bridge is closed. The new structure would be built 14 ft to the south of the existing structure, utilizing Typical Section B, as shown in Figure 2-3.

Both west and east of the bridge the roadway approach maintains the existing two-lane undivided rural roadway configuration. On the west approach, a 2-ft curb-and-gutter will be added on the north side of the roadway from the beginning of construction continuing to the easternmost Kingfish Boat Ramp driveway, consistent with the proposed Kingfish Boat Ramp improvement project discussed in Section 3.4.3; additionally, the curb-and-gutter provides more area for SMF E. The remaining shoulders on each side of the proposed roadway will be 10 ft with 5 ft paved, increased from the existing 8-ft shoulders with 4 ft paved; this will bring the shoulders up to current FDOT design standards. The bridge includes a 10-ft sidewalk on both sides. The 10-ft sidewalk on the north side will transition to the existing 8-ft sidewalk. On the south side of the roadway a 10-ft sidewalk will be provided from SR 789 (East Bay Drive) to Perico Bay Boulevard. The proposed typical section of the roadway west and east of the bridge is shown in Figure 2-7. The roadway is consistent with the bridge typical section except that the northern Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 2-13

sidewalk is decreased in width to 8 ft by utilizing the existing sidewalk. The roadway at the bridge approaches is similar to the proposed bridge except it is elevated on embankment with a 1:2 slope on each side. The 1:2 slope will have a concrete slope pavement surface and will prevent the type of erosion evident in the existing sloped embankment.

Taking into account the MHW elevation of 1.09 ft, the proposed profile accommodates a minimum 21-ft vertical navigational clearance over the existing Gulf Intracoastal Waterway, similar to the existing clearance. Maximum grades of 2.8 percent are joined by a 549-ft cresting vertical curve through the bascule portion of the structure. The fixed approaches to the bascule bridge accommodate an 8-ft structure depth, except in the westernmost 225 ft and easternmost 248 ft of the bridge where the structure depth was reduced to 5 ft. This reduced structure depth was used to decrease environmental impacts by lowering the elevations of the west and east abutments which minimized the footprint of the proposed sloped abutments. The bascule span structure depth is assumed to be 10 ft. The proposed bascule bridge will be 3,596.07 ft in length, and will reach a maximum elevation of 33.31 ft in the closed position; this increase from the existing 30.00-ft elevation will allow for the 12-ft splash zone discussed earlier.

The bascule portion would consist of two bascule leaves forming a 192-ft span. As previously explained, all superstructure components would be located above the splash zone. Access from SR 64 (Manatee Avenue) to the Kingfish Boat Ramp west of the bridge and the commercial driveways east of the bridge could continue operating similar to existing conditions. As with the existing condition, the proposed bridge will not accommodate vehicular traffic under the bridge from one side of the causeway to the other.

2.6.3 ALTERNATIVE 2BN – MID-LEVEL BASCULE, TYPICAL SECTION B, NORTH ALIGNMENT

Alternative 2BN would replace the existing Anna Maria Island Bridge with a new mid-level bascule structure similar to the existing structure, with a 45-ft vertical navigational clearance when the bridge is closed. The new structure would be built to the north of the existing structure, utilizing Typical Section B, as shown in Figure 2-3.

Both west and east of the bridge the roadway approach maintains the existing two-lane undivided rural roadway configuration. On the west approach, a 2-ft curb-and-gutter will be added on the north side of the roadway from the beginning of construction continuing to the proposed bridge barrier wall, consistent with the proposed Kingfish Boat Ramp improvement project. The remaining shoulders on each side of the proposed roadway will be 10 ft with 5 ft paved, increased from the existing 8-ft shoulders with 4 ft paved; this will bring the shoulders up to current FDOT design standards. The bridge includes a 10-ft sidewalk on both sides. The 10-ft sidewalk on the north side will transition to the existing 8-ft sidewalk. On the south side of the roadway a 10-ft sidewalk will be provided from SR 789 (East Bay Drive) to Perico Bay Boulevard. The proposed typical section of the roadway west and east of the bridge is shown in Figure 2-7. The roadway at the bridge approaches is similar except it is elevated on embankment with a 1:2 slope on each side. The 1:2 slope will have a concrete slope pavement surface and will prevent the type of erosion evident in the existing sloped embankment. The proposed roadway is consistent with the bridge typical section except that the northern sidewalk is decreased in width

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to 8 ft since it will be constructed by Manatee County as part of the Kingfish Boat Ramp improvements on the west and matches the existing sidewalk width on the east.

Taking into account the MHW elevation of 1.09 ft, the proposed profile accommodates a minimum 45-ft vertical navigational clearance over the existing Gulf Intracoastal Waterway. Based on data provided by the bridge tender at Anna Maria Island Bridge, this vertical clearance will allow approximately 39 percent of the waterway users that currently require the bridge to open to pass without an opening. Maximum grades of 4 percent are joined by a 784-ft cresting vertical curve through the bascule portion of the structure. The fixed approaches to the bascule bridge accommodate an 8-ft structure depth, except in the westernmost 226 ft and easternmost 246 ft of the bridge where the structure depth was reduced to 5 ft. This reduced structure depth was used to decrease environmental impacts by lowering the elevations of the west and east abutments which minimized the footprint of the proposed sloped abutments. The bascule span structure depth is assumed to be 10 ft. The proposed bascule bridge will be 3,596.07 ft in length, and will reach a maximum elevation of 56.31 ft in the closed position.

The bascule portion would consist of two bascule leaves forming a 192-ft span. As previously explained, all superstructure components would be located above the splash zone. Alternative 2BN will encroach on the existing navigational channels which run along the northern side of the existing bridge. This alternative will impede navigation which may require dredging to restore. Access from SR 64 (Manatee Avenue) to the Kingfish Boat Ramp west of the bridge will also be impacted. Three driveways currently provide access to the boat ramp and help facilitate smooth vehicle circulation with logical points of entry and exit; this alternative will require the closure of the easternmost driveway and the truncation of the center driveway. These modifications will greatly decrease the available parking and hamper vehicle circulation, as well as reduce the staging area used by vehicles for launching and retrieving watercraft. The commercial driveways east of the bridge could continue operating similar to existing conditions. As with the existing condition, the proposed bridge will not accommodate vehicular traffic under the bridge from one side of the causeway to the other.

2.6.4 ALTERNATIVE 2BS – MID-LEVEL BASCULE, TYPICAL SECTION B, SOUTH ALIGNMENT

Alternative 2BS would replace the existing Anna Maria Island Bridge with a new mid-level bascule structure similar to the existing structure, with a 45-ft vertical navigational clearance when the bridge is closed. The new structure would be built 14 ft to the south of the existing structure, utilizing Typical Section B, as shown in Figure 2-3.

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roadway a 10-ft sidewalk will be provided from SR 789 (East Bay Drive) to Perico Bay Boulevard. The proposed typical section of the roadway west and east of the bridge is shown in Figure 2-7. The roadway at the bridge approaches is similar except it is elevated on embankment with a 1:2 slope on each side. The 1:2 slope will have a concrete slope pavement surface and will prevent the type of erosion evident in the existing sloped embankment.

Taking into account the MHW elevation of 1.09 ft, the proposed profile accommodates a minimum 45-ft vertical navigational clearance over the existing Gulf Intracoastal Waterway. Based on data provided by the bridge tender at Anna Maria Island Bridge, this vertical clearance will allow approximately 39 percent of the waterway users that currently require the bridge to open to pass without an opening. Maximum grades of 4 percent are joined by a 784-ft cresting vertical curve through the bascule portion of the structure. The fixed approaches to the bascule bridge accommodate an 8-ft structure depth, except in the westernmost 225 ft and easternmost 248 ft of the bridge where the structure depth was reduced to 5 ft. This reduced structure depth was used to decrease environmental impacts by lowering the elevations of the west and east abutments which minimized the footprint of the proposed sloped abutments. The bascule span structure depth is assumed to be 10 ft. The proposed bascule bridge will be 3,596.07 ft in length, and will reach a maximum elevation of 56.31 ft in the closed position.

2.6.5 ALTERNATIVE 3BN – HIGH-LEVEL FIXED-BRIDGE, TYPICAL SECTION B, NORTH ALIGNMENT

Alternative 3BN proposes to replace the existing Anna Maria Island Bridge with a new high-level fixed-bridge structure providing 65 ft of vertical clearance over the Gulf Intracoastal Waterway. The new structure would be built 10 ft to the north of the existing structure, utilizing Typical Section B (fixed-bridge portion only), as shown in Figure 2-3.

Both west and east of the bridge the roadway approach maintains the existing two-lane undivided rural roadway configuration. On the west approach, a 2-ft curb-and-gutter will be added on the north side of the roadway from the beginning of construction continuing to the proposed bridge barrier wall, consistent with the proposed Kingfish Boat Ramp improvement project. The remaining shoulders on each side of the proposed roadway will be 10 ft with 5 ft paved, increased from the existing 8-ft shoulders with 4 ft paved; this will bring the shoulders up to current FDOT design standards. The bridge includes a 10-ft sidewalk on both sides. The 10-ft sidewalk on the north side will transition to the existing 8-ft sidewalk. On the south side of the roadway a 10-ft sidewalk will be provided from SR 789 (East Bay Drive) to Perico Bay Boulevard. The proposed typical section of the roadway west and east of the bridge is shown in Figure 2-7. The roadway at the bridge approaches is similar except it is elevated on embankment with a 1:2 slope on each side. The 1:2 slope will have a concrete slope pavement surface and will prevent the type of erosion evident in the existing sloped embankment. The proposed roadway is

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consistent with the bridge typical section except that the northern sidewalk is decreased in width to 8 ft since it will be constructed by Manatee County as part of the Kingfish Boat Ramp improvements on the west and matches the existing sidewalk width on the east.

Taking into account the MHW elevation of 1.09 ft, the proposed profile accommodates a minimum 65-ft vertical navigational clearance over the existing Gulf Intracoastal Waterway. Based on data provided by the bridge tender at Anna Maria Island Bridge, this vertical clearance will allow approximately 99 percent of the waterway users that currently require the bridge to open to pass without an opening. Maximum grades of 4 percent are joined by a 784-ft cresting vertical curve. The fixed-bridge accommodates an 8-ft structure depth, except in the westernmost 161 ft and easternmost 171 ft of the bridge where the structure depth was reduced to 5 ft. This reduced structure depth was used to decrease environmental impacts by lowering the elevations of the west and east abutments which minimized the footprint of the proposed sloped abutments. The proposed fixed-bridge will be 3,455.79 ft in length, and will reach a maximum elevation of 74.31 ft.

As previously explained, all superstructure components would be located above the splash zone. Alternative 2BN will encroach on the existing navigational channels which run along the northern side of the existing bridge. This alternative will impede navigation which may require dredging to restore. Access from SR 64 (Manatee Avenue) to the Kingfish Boat Ramp west of the bridge will also be impacted. Three driveways currently provide access to the boat ramp and help facilitate smooth vehicle circulation with logical points of entry and exit; this alternative will require the closure of the easternmost driveway and the truncation of the center driveway. These modifications will greatly decrease the available parking and hamper vehicle circulation, as well as reduce the staging area used by vehicles for launching and retrieving watercraft. The commercial driveways east of the bridge could continue operating similar to existing conditions. As with the existing condition, the proposed bridge will not accommodate vehicular traffic under the bridge from one side of the causeway to the other.

2.6.6 ALTERNATIVE 3BS – HIGH-LEVEL FIXED-BRIDGE, TYPICAL SECTION B, SOUTH ALIGNMENT

Alternative 3BS proposes to replace the existing Anna Maria Island Bridge with a new high-level fixed-bridge structure providing 65 ft of vertical clearance over the Gulf Intracoastal Waterway. The new structure would be built 14 ft to the south of the existing structure, utilizing Typical Section B (fixed-bridge portion only), as shown in Figure 2-3.

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Boulevard. The proposed roadway at the west and east bridge approaches is similar to the proposed bridge except it is elevated on embankment with a 1:2 slope on each side. The 1:2 slope will have a concrete slope pavement surface and will prevent the type of erosion evident in the existing sloped embankment. Figure 2-7 shows the proposed roadway at-grade west and east of Anna Maria Island Bridge, which is consistent with the bridge typical section except that the northern sidewalk is decreased in width to 8 ft.

Taking into account the MHW elevation of 1.09 ft, the proposed profile accommodates a minimum 65-ft vertical navigational clearance over the existing Gulf Intracoastal Waterway. Based on data provided by the bridge tender at Anna Maria Island Bridge, this vertical clearance will allow approximately 99 percent of the waterway users that currently require the bridge to open to pass without an opening. Maximum grades of 4 percent are joined by a 784-ft cresting vertical curve. The fixed-bridge accommodates an 8-ft structure depth, except in the westernmost 147 ft and easternmost 187 ft of the bridge where the structure depth was reduced to 5 ft. This reduced structure depth was used to decrease environmental impacts by lowering the elevations of the west and east abutments which minimized the footprint of the proposed sloped abutments. The proposed fixed-bridge will be 3,451.65 ft in length, and will reach a maximum elevation of 74.31 ft.

As previously explained, all superstructure components would be located above the splash zone. Access from SR 64 (Manatee Avenue) to the Kingfish Boat Ramp west of the bridge and the commercial driveways east of the bridge could continue operating similar to existing conditions. As with the existing condition, the proposed bridge will not accommodate vehicular traffic under the bridge from one side of the causeway to the other.

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SECTION 3.0 ANALYSIS OF FLOODPLAIN IMPACTS

This project is within a coastal floodplain. Flooding is due to tidal storm surge and not to river flow overtopping its banks. The roadway alignments do traverse coastal floodplain shorelines and thus have the potential to impact wetlands which provide habitat for various fauna. 3.1 PROJECT SETTING AND LAND USE

The project corridor is along existing SR 64 (Manatee Avenue). SR 64 (Manatee Avenue) runs in an east to west direction from the peninsula mainland of Florida across Palma Sola Bay to Perico Island and then across the northern end of Sarasota Bay to Anna Maria Island, a barrier island at the Gulf of Mexico (Figure 3-1). Tampa Bay is north of the bridge, and the Gulf Intracoastal Waterway extends from Tampa Bay, south under the bridge and into Big Sarasota Bay. Big Sarasota Bay extends 21 miles (mi) from south Tampa Bay to Big Sarasota Pass at Phillipi Creek. The bay becomes narrow at Phillipi Creek, thus is named Little Sarasota Bay for the remaining 12 mi to the south. Additionally, the Manatee River runs generally parallel and to the north of SR 64 (Manatee Avenue) to empty into south Tampa Bay just north and east of the north end of Big Sarasota Bay (see Figures 3-2 through 3-4). The corridor is within an urbanized setting, with most urbanization concentrated at the west end of the project. Within the study area, identified land uses are categorized according to the Florida Land Use Cover and Forms Classification System (FLUCFCS) include: Residential, High Density (FLUCFCS 130), High Density Under Development (FLUCFCS 139), Commercial and Services (FLUCFCS 140), Recreational (FLUCFCS 180), Open Land (FLUCFCS 190), and Roads and Highways (FLUCFCS 814). Within the anticipated project construction limits, land use is primarily Recreational and Highway. There is a county boat ramp along the westerly approach, then the crossing of the Gulf Intracoastal Waterway, and at the easterly approach, a conservation area and proposed park on the south, with commercial and residential development on the north. 3.2 NATIONAL FLOOD INSURANCE PROGRAM COMMUNITIES

The project study area lies within three separate communities with regard to administration of the National Flood Insurance Program (NFIP) under the Federal Emergency Management Agency (FEMA). From west to east, the communities are: Holmes Beach (community number 125114); unincorporated Manatee County (community number 120153); and City of Bradenton (community number 120155). The proposed project limits lie principally within unincorporated Manatee County and within the City of Bradenton. Most of the existing 3125-foot (ft) bridge lies within Manatee County whereas the roadway east of the bridge is within the City of Bradenton.

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3.3 FLOODPLAINS

The floodplain limits have been identified based upon tidal surge studies as described in the Flood Insurance Study for Manatee County. Flood elevations for the western approach roadway and the channel are shown on map panel 120153-0302 B, and for the eastern approach roadway on map panel 120155-0005 C. The flood elevations range from elevation 9 ft on the west side of the bridge causeway to elevation 12 ft on the east side. All elevations are referenced to National Geodetic Vertical Datum (NGVD) 1929 unless otherwise noted. The increase from west to east is likely due to the dampening effect of Anna Maria Island west of the bridge and the open water of Tampa Bay to the north of the bridge. Refer to Figures 3-5a through 3-5c.

3.3.1 FLOODPLAIN IMPACTS MID AND LOW-LEVEL ALTERNATIVES

The floodplain impacts for the Low and Mid-Level Bascule Alternatives will be the same because the approach geometry is the same for each of these vertical alignments. As previously stated, the flood elevations increase from elevation 9 ft to elevation 12 ft (NGVD 1929) from the west side of the bridge causeway to the east side of the bridge causeway. At the west end of the bridge, the flood elevation is shown as elevation 11 ft. Floodplain fill should therefore be determined based upon increases in fill heights up to the point where the existing profile is at or above the noted flood elevations. The approach roadway on the west side of the bridge will have profile grade elevations 0.5 to 1.5 ft above existing over a distance of about 270 ft before intersecting the point where the existing ground is at or above elevation 11.0 ft. On the east, the profile grade will go from existing to about 2 ft above existing ground over about 290 ft before the alignment intercepts the point where existing ground is at or above elevation 12.0 ft. Therefore, the overtopping width along the approach roadways is reduced by about 50 ft on the west approach and by about 60 ft on the east approach. However, there is about 1,000 ft of roadway on the west causeway that will remain at existing ground (approximately elevation 6.5) and on the east, there is over 500 ft of roadway within the project limits on the east causeway that will remain at existing ground (also approximately elevation 6.5). Additionally, the bridge opening will be increased by about 470 ft and the distance between piers will be reduced, thus total conveyance capacity will not be reduced.

3.3.2 FLOODPLAIN IMPACTS HIGH-LEVEL ALTERNATIVE

The High-Level Fixed-Span Alternative approach roadways will be raised above existing ground for a longer distance; about 410 ft on the west and about 550 ft on the east. The longer length of fill is due to a longer run of 0.3 percent grade approaching the 4 percent rise to the higher bridge crest. This vertical geometry results in less reduction in overtopping length as compared to the Mid and Low-Level Alternatives. On the west, the overtopping length (that length below elevation 11.0 ft) is reduced by 15 ft and on the east, the overtopping length (length below elevation 12.0 ft, is reduced by 50 ft. The High-Level Fixed-Span bridge length is about 144 ft shorter than the Low and Mid-Level Bascule Alternatives, but is still more than 220 ft longer than the existing bridge, thus conveyance capacity will not be reduced.

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3.3.3 OTHER CROSS DRAINS

There is a 24-inch (in) cross drain within the project limits. This drain is at approximately station 165+50, about 1,362 ft from the east end of the bridge. This cross drain has a ditch bottom inlet on the upstream end. It is within the limits of construction where the roadway is in realignment and will need extension or replacement, depending upon its condition at the time of construction. The cross drain will be analyzed to determine its existing drainage area and capacity and will also be analyzed for any extension or modification. There is a 9-ft by 6-ft box culvert that is approximately 1,200 ft further east; this is well outside the project limits.

3.3.4 STORMWATER MANAGEMENT FACILITIES

Stormwater Management Facilities (SMF) will be required for this project because it will not qualify for the General Permit for bridge replacement (see Final Pond Siting Report). The ponds will be constructed within the floodplain on the current causeway fill. The ponds are proposed to provide stormwater treatment only, attenuation of flow is not required because the discharge is directly to tidal waters.

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SECTION 4.0 STUDY REQUIREMENTS

The Florida Department of Transportation (FDOT) Project Development & Environment Manual, Part 2: Analysis and Documentation; Chapter 24, addresses Location Hydraulic Studies. These studies are required by the Federal-Aid Policy Guide 23 Code of Federal Regulations (CFR) 650A Section 650.111. This chapter lists specific items of discussion and evaluations required for various levels of impact. 4.1 DISCUSSION

The items 1-6, enumerated below must be addressed commensurate with the significance of the flood risk or environmental impact, for all alternatives with floodplain encroachment or which would support base floodplain development.

1. The practicability of alternatives to any longitudinal encroachments 2. The risks associated with implementation of the action 3. The impacts on natural and beneficial floodplain values 4. The support of incompatible floodplain development 5. The measures to minimize floodplain impacts 6. The measures to restore and preserve the natural and beneficial floodplain values impacted

Encroachments are categorized as Significant or Minimal depending upon impacts to natural and beneficial floodplain values and potential for impacts on human life and transportation facilities. Those encroachments that would increase flood elevations and/or would cause or promote significant changes to the flood storage, recharge capacity, or other natural floodplain values would be considered significant; as would those that would promote development in the floodplain. Typically, replacement structures on existing alignments that are designed to the FDOT and local Water Management District standards will have minimal impact. This project is considered to have minimal impact. 4.2 ITEMS TO BE ADDRESSED

4.2.1 ITEMS REGARDING FLOODPLAIN FILL ENCROACHMENT

The following items (1-10) are items enumerated in Chapter 24-2.2.1 (b), FDOT Project Development & Environment Manual, which must be addressed to document the anticipated encroachment for each alternative anticipated to have minimal encroachment; each item is followed by the resulting analysis for this project.

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1. The history of flooding of the existing facilities and/or measures to minimize any impacts due to the proposed improvements. Based upon the profile of the existing facility, and normal tidal elevations, the roadway is subject to flooding only during tidal events that would cause tidal surges in excess of 6 feet (ft) National Geodetic Vertical Datum (NGVD). These events would be associated with tropical storms. The proposed profile for all alignments will be at or above the existing profile elevations.

2. Determination of whether the encroachment is longitudinal or transverse, and if it is a longitudinal encroachment an evaluation and discussion of practicable avoidance alternatives. The encroachment for all alignments is a transverse encroachment. The proposed alternative alignments are parallel to and tie into the existing alignment.

3. The practicability of avoidance alternatives and/or measures to minimize impacts. Because this is a replacement structure of a bridge that connects a barrier island to the mainland, there is no practical alternative alignment which would avoid all impacts to floodplains or wetlands. Measures will be taken during final design to minimize fill within floodplain wetlands.

4. Impact of the proposed improvement on emergency services and evacuation. Based upon the profile of the existing facility, and normal tidal elevations, the roadway is subject to flooding only during tidal events that would cause tidal surges in excess of 6 ft NGVD. The proposed profile will be at or above the existing profile elevations. The Mid-Level Bascule and High-Level Fixed-Span Alternatives would improve emergency service access and evacuation because there would be fewer to no interruptions to traffic due to bridge openings.

5. Impacts of the proposed improvement on the base flood, likelihood of flood risk, overtopping, location of overtopping, backwater, etc. The anticipated profiles of the various alternatives are very close to the existing profile except within the bridge limits. The length of overtopping is slightly reduced with all of the vertical alignments, but the overall length of overtopping on both the west and east approaches is still over 1,000 ft, at essentially a flat grade, therefore location of overtopping is not changed and backwater is not increased. Because the flooding here is due to tidal surge, profile changes should have no effect on flood elevation.

6. Determination of the impact of the proposed improvements on regulatory floodways, if any, and documentation of coordination with the Federal Emergency Management Agency (FEMA) and local agencies to determine the project’s consistency with the regulatory floodway. This crossing is over a tidal area and is subject to flooding due to tidal storm surge. There is no regulatory floodway associated with storm surge.

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7. The impacts on natural and beneficial floodplain values, and measures to restore and preserve these values (this information may also be addressed as part of the wetland impact evaluation and recommendations). Project construction is subject to specific regulations which address sediment and erosion control. FDOT specifications require adherence to state and federal regulations which govern construction, thus project plans are required to include measures to protect the natural and beneficial floodplain values. The Wetland Evaluation Report, prepared as part of this Project Development and Environment (PD&E) Study further addresses floodplain wetlands.

8. Consistency of the proposed improvements with the local floodplain development plan or the land use elements in the Comprehensive Plan, and the potential of encouraging development in the base floodplain. The project is consistent with the land use elements in the Manatee County Comprehensive Plan because this is solely a bridge replacement project, no capacity increase proposed. Development within the floodplain is regulated by federal, state and local laws.

9. A map showing project, location, and impacted floodplains. Copies of applicable Flood Insurance Rate Maps (FIRM) should be included in the Appendix. Figures 3-5a through 3-5c show the project in relation to the floodplain.

10. Results of any risk assessments performed. The FDOT Project Development & Environment Manual, Part 2, Chapter 24, defines Risk Assessment and Risk Analysis:

• A Risk Assessment is a subjective analysis of the risks resulting from various design alternatives, without detailed quantification of flood risks and losses. A risk assessment is…… for structures whose size is not influenced by hydraulic constraints. • Risk Analysis encompasses an economic comparison of alternatives using expected total costs (construction costs plus risks costs) to determine the alternative with the least total expected cost to the public. It shall include probable flood related costs during the service life of the facility for highway operation, maintenance, and repair, for highway aggravated flood damage to other property, and for additional or interrupted highway travel.

The Risk Assessment for this project consisted of comparing the alternative profiles and alignments to the existing alignment to qualitatively evaluate whether there would be changes in flood elevation or in roadway flooding overtop lengths or locations. There will be minor decreases in the total overtopping length due to changes in road profiles; however the decrease is not more than 6 percent of the total overtopping length for the anticipated 100-year storm surge elevation. The result of the project is that traffic will move more efficiently and emergency vehicles will have better access because there will be full width (10-ft) shoulders included on the bridge; additionally, the Mid-Level

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Bascule and High-Level Fixed-Span alternatives will accommodate approximately 39 percent to over 99 percent, respectively, all of the navigational traffic without traffic interruption, thus these alternatives would improve roadway traffic flow.

4.2.2 ITEMS REGARDING PROJECTS WITH BRIDGES

If a Bridge Hydraulic Report is not prepared during Project Development, the following items must be addressed in the Location Hydraulic Report (LHR): a. Conceptual bridge length b. Conceptual scour considerations c. Preliminary vertical grade requirements

Conceptual Bridge Length

Conceptual bridge lengths have been determined based upon providing sloped abutments at 1:2 slopes with the toe of slope above the mean high water (MHW) elevation of 1.09 ft NGVD 1929. The bridge length for the Low and Mid-Level alternatives is approximately 3,596 ft for both the north and south alignments. The High-Level alternative bridge length is approximately 3,456 ft for both the north and south alignments.

The bridge lengths are longer than the existing bridge because the existing bridge has a vertical bulkhead with top elevation at approximately 3.0. The existing bridge approaches were constructed on a causeway whereas the proposed bridge approaches will maintain the approach roadway footprint within the current causeway at an elevation above the MHW.

Conceptual Scour Considerations

There was a PD&E Study performed in 1998 for replacement of this bridge. That study contained a plot of soil boring logs from four borings taken in December 1988. Two of the borings were taken just outside the main channel, and two were taken near the abutment bulkheads. The soil profiles extended to depths of 78 to 80 ft and show the upper strata to be comprised of fine sand with shells. The fine sand with shells extends for 12 to more than 40 ft. This layer is underlain by sandy to silty clay and, in 1 of the 4 borings, silty clay with limestone at a depth of 70 ft. (see Figures 4-1a and 4-1b). These are erodible soils and would be considered highly susceptible to scouring forces.

The 1998 Preliminary Engineering Report (PER), Section 8.3.2, notes that no significant amounts of scour are noticeable from the bridge inspection reports. A more recent bridge inspection report, dated May of 2007 has a comparison of channel elevations from the 1997, 2005 and 2007 depth measurements. Those measurements show no perceptible change in elevation (see Figure 4-2). The existing bridge is not rated “scour critical.”

For this LHR, the National Oceanic Atmospheric Administration (NOAA) Navigational Charts were referenced to ascertain general site conditions regarding normal tidal currents and flow paths within the project vicinity. Chart 11425 has a table of average velocities at Flood and Ebb tide. North of the Cortez Bridge, which is about 1.6 miles (mi) south of the SR 64 (Manatee Avenue) bridge, the average velocity at flood tide is 0.6 knots (~ 1 ft/second) and at ebb tide, the

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average velocity is 0.1 knots (~0.17 ft/second). At Passage Key Inlet, located just north of the northern tip of Ann Maria Island, the flood and ebb tide average velocities are noted as 0.9 knots (1.5 ft/second) and 1.1 knots (1.85 ft/second). At Longboat Pass, about 1.4 mi south of the Cortez Bridge, the flood and ebb average velocities are 1.8 knots and 1.6 knots, respectively

The SR 64 (Manatee Avenue) bridge over Anna Maria Sound is located just south of the opening to Tampa Bay, which is a very large bay that has several ancillary bays along its perimeter. Additionally, the SR 64 (Manatee Avenue) bridge is at the north end of Big Sarasota Bay, an elongated, moderately wide bay that has four outlets: at the north, the outlet is to south Tampa Bay through Anna Maria Sound. The other three outlets are directly to the Gulf: Longboat Pass is about 3.2 mi south of SR 64 (Manatee Avenue); Big Sarasota Pass is at the south end of Big Sarasota Bay, about 15 mi south of SR 64 (Manatee Avenue); and New Pass is about 2 mi north of Big Sarasota Pass. The Manatee River empties into south Tampa Bay just north and east of the SR 64 (Manatee Avenue) crossing of Anna Maria Sound (at the north end of Big Sarasota Bay) (see Figures 3-2 through 3-4).

Typically, scour is a problem at tidal bridges where relatively narrow tidal inlets open in to large bays or estuaries where there is a large amount of storage available. The rising tide pushes water through the inlet and into the bay or estuary and as the tide recedes, the large volume of tidal storage prism is forced through the narrow inlet due to the head differential created by the ebb tide. Johns Pass, to the north of Tampa Bay, leads to the northern end of Boca Ciega Bay. This Bay has a significant amount of storage and only two relatively narrow inlets; Johns Pass and Blind Pass. Outlet capacity to the south, into lower Boca Ciega Bay (which opens into Tampa Bay), is limited by winding and narrow channels. Scour at this inlet has been documented as continual and severe.

By contrast, the SR 64 (Manatee Avenue) bridge opening over Anna Maria Sound is not restrictive; it spans 3,125 ft, which is wider than any of the other openings to Big Sarasota Bay. It is possible that waves could be generated by hurricane winds and storm surge from north to south across Tampa Bay and into Anna Maria Sound and this could cause scour as water is forced into the bay. However, on a normal day to day basis, there is minimal scour potential because of the general layout of the bays around this location. The opening at SR 64 (Manatee Avenue) is greater than that of the other causeways or inlets. Also, the Manatee River empties into Tampa Bay just north and east of Anna Maria Sound, and provides some sediment replenishment to the area. A complete scour analysis will be completed as part of the Bridge Hydraulic Report that will be required for this bridge during final design.

Preliminary Vertical Grade Requirements

The roadway profile has been set to allow for the minimum clearances with regard to superstructure distance to the water surface and with regard to existing clearance and required navigation clearance for a fixed-bridge. The Low-Level profile maintains the existing navigation clearance of 21 ft above MHW with the bascule bridge in the closed position. Likewise, the Mid-Level bridge maintains the existing navigational clearance for the bridge outside the channel and increases clearance at the bascule bridge by 24 ft. The High-Level bridge meets the united States Coast Guard (USCG) guidelines for vertical clearance on the Gulf Intracoastal Waterway; that clearance is 65 ft above MHW. Additionally, deck drainage is improved for the Low and

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Mid-Level alternatives by proposed minimum 0.3 percent grade on the bridge (existing is 0.0 percent).

The approach roadways are more than 5 ft above the MHW, thus the roadway approaches are not subject to inundation except in extreme tidal storm events. Where the roadway is adjacent to stormwater ponds and is below profile grade elevation of 7.0, there will be less than 2 ft of base clearance assuming that the weir elevation in the ponds is set at elevation 3.5 ft. If this is a concern for the structural integrity of the pavement, black base could be used along the pond limits.

The bridge profile maintains the bottom of the low beam a minimum of 12 ft above MHW, thus the elevation of bottom of beam would be 13.1 ft NGVD 1929. The anticipated 100-year storm surge is elevation 11.0 ft at the west end of the bridge and elevation 12.0 ft at the east end. The greatest storm surge experienced in this area occurred in conjunction with the 1921 Tampa Bay Hurricane. This storm was estimated to be a Category 4 storm (Saffer-Simpson scale) that produced a storm surge elevation of 10.5 ft at Tampa.

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SECTION 5.0 FLOODPLAIN COORDINATION

In accordance with the Federal Highway Administration (FHWA) and state of Florida requirements, local floodplain management regulations were reviewed to ascertain local floodplain crossing requirements, and floodplain managers were contacted to ascertain status of floodplain studies. 5.1 MANATEE COUNTY

Manatee County has land development regulations that address floodplain fill. These are within Section 718, Floodplain Management of the Land Development Code. These regulations address development within the floodplain and pertain primarily to buildings. Section 718.6.2.2.2 addresses landscape fill. There are two concerns listed in that section that explain the rationale for restrictions on fill, the specific concerns are as follows:

• Section 718.6.2.2.2.2 - Volume and distribution of fill will not cause wave deflection to adjacent properties • Section 718.6.2.2.2.3 - Slope of fill will not cause wave run-up or ramping

5.2 CITY OF HOLMES BEACH

Article IX of the Land Development Code for the City of Holmes Beach addresses Floodplain Development. Similar to Manatee County, the regulations pertain primarily to building development within the floodplain. Section 9.16 addresses Coastal high hazard areas. Item number 12 under that section states the following:

When fill is proposed, in accordance with the permit issued by the state department of environmental protection, in a coastal high hazard area, the development permit shall be issued only upon demonstration by appropriate engineering analyses that the proposed fill will not increase the water surface elevation of the base flood nor cause any adverse impacts to adjacent properties by wave ramping and deflection. 5.3 CITY OF BRADENTON

There are no specific requirements within the City of Bradenton Code that pertain to floodplain management except for compliance with the requirements of the Southwest Florida Water Management District (SWFWMD). 5.4 SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT

There are no specific requirements for roadways in coastal floodplains. However, SWFWMD typically requires floodplain fill compensation. Anna Maria Island Bridge PD&E Study Final Location Hydraulic Report 5-1

SECTION 6.0 CONCLUSIONS

6.1 CONCLUSIONS

In addition to the No-Build Alternative and a Rehabilitation Alternative, this study evaluated two horizontal alignments for bridge replacement; the north alignment and the south alignment. The study also evaluated two typical sections. Both typical sections maintain the current two lanes of traffic (one each eastbound and westbound), and include 10-foot (ft) shoulders. Typical Section A has one 12-ft wide sidewalk on the north side and Typical Section B has a 10-ft wide sidewalk on both the north and south side of the bridge. Additionally, three general bridge replacement alternatives were investigated; Low-Level Bascule, Mid-Level Bascule, and High-Level Bascule. The Low-Level Bascule accommodates a 21-ft vertical navigational clearance; the Mid-Level Bascule increases vertical navigational clearance to 45 ft; and the High-Level Fixed-Span accommodates 65 ft of vertical navigational clearance.

All of the alternatives are within the coastal floodplain and are subject to flooding to some degree due to tidal storm surges. All alternatives will have some minor impact to the floodplain but flood elevations and risks will not be increased due to the changes in vertical or horizontal alignments presented in this study.

Anna Maria Bridge PD&E Study Final Location Hydraulic Report 6-1

SECTION 7.0 REFERENCES

1. Hydraulic Engineering Circular No. 25; Publication No. FHWA-NHI-07-096; Federal Highway Administration; June 2008. 2. Straight Line Diagram of Road Inventory, Manatee County, Section 13150000; Florida Department of Transportation, District One; January 8, 2004. 3. Preliminary Engineering Report Anna Maria Island Bridge Replacement Study; Florida Department of Transportation, District One; 1998. 4. Vessel Height/Mast Survey Results Bridge Replacement Study; Florida Department of Transportation, Efficient Decision Transportation Making (EDTM); 2008. http://www.annamariaislandbridge.com/pi.htm 5. Plans Preparation Manual; Volume I, Chapters, 2, 27; Florida Department of Transportation; 2009. http://www.dot.state.fl.us/rddesign/PPMManual/2009/Volume1/zChap02.pdf 6. Project Development and Environment Manual, Part 2, Chapter 24, (as updated January 7, 2008); Florida Department of Transportation; 1991. http://www.dot.state.fl.us/emo/pubs/pdeman/pdeman.htm 7. Standard Specifications for Road and Bridge Construction; Florida Department of Transportation; 2007. 8. A Historical Geography of Southwest Florida Waterways Volume One; Anna Maria Sound to Lemon Bay; Florida Sea Grantl Geography of Southwest Florida Waterways Volume One; Anna Maria Sound to Lemon Bay, Antonini, Fann, and Roat. http://www.sarasota.wateratlas.usf.edu/shared/historic.asp 9. Municipal Code Corporation; Online Library; Referenced for Manatee County, City of Holmes Beach, City of Bradenton. http://www.municode.com/resources/OnlineLibrary.asp 10. National Oceanic and Atmospheric Administration (NOAA), Office of Coast Survey; Nautical Charts and Publications. http://www.charts.noaa.gov/OnLineViewer/GulfCoastViewerTable.shtml

11. The Reanalysis of Three Catastrophic Hurricanes that Impacted Florida During the 1920’s; National Oceanic and Atmospheric Administration (NOAA), Hurricane Research Division, Miami, FL., Feuer, Landsea, Sims, and Woolcock. (PowerPoint Presentation) www.aoml.noaa.gov/hrd/hurdat/presentations/irr_040819.ppt 12. United States Department of Agriculture, Natural Resources Conservation Service. 2008. Web Soil Survey of Manatee County. http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx

Anna Maria Bridge PD&E Study Final Location Hydraulic Report 7-1