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City of Miami Beach, 1700 Convention Center Drive, Miami Beach, Florida 33139, www.miamibeachfl.gov
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| | | | | | | | | | Item 23.
COMMITTEE MEMORANDUM | | | |
| | | | | | | | TO: Land Use and Sustainability Committee
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| FROM: Jimmy L. Morales, City Manager
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| DATE: January 21, 2020
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| | | | | | | | | TITLE: | DISCUSSION TO REVIEW THE PALM AND HIBISCUS ROAD ELEVATION EXPERIENCE.
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| | | | | | | | HISTORY:
| On September 11, 2019, the City Commission referred a discussion item to the former Sustainability and Resiliency Committee to review the Palm and Hibiscus project’s road elevation experience. During the discussion of the item, the Commission also included the Venetian Islands, Lower North Bay Road, Sunset Harbour, and Alton Road projects. Staff was asked to evaluate the impact of road raising on private properties, as well as how road raising affects the project schedule and costs. The overall efficacy of road raising and lessons learned from previous projects were also evaluated.
PALM AND HIBISCUS ISLANDS
The construction of the Palm and Hibiscus Island Enhancements commenced on January 2016. One of the main goals of the project was to address rainfall flooding with a new storm water drainage system, while addressing sea level rise and tidal flooding by raising roads.
Road raising occurred within both islands. However, depending on the elevation of the existing roadway, roads were raised different amounts to achieve the desired crown elevation. Some of the lower lying areas with elevations as low as 1.25 ft NAVD, such as the Coconut Lanes, experienced road raising up to two feet above the pre-construction elevation.
In addition to raising the roads, new storm water system and pump stations, the project also included the installation of the new water lines, sanitary sewer line rehabilitation, LED lighting, asphalt restoration, striping and signage, and landscape restoration.
VENETIAN ISLANDS
The Venetian Islands Neighborhood Project commenced construction in November 2013. The project originally included a new 8” water main, new water services, a gravity drainage system including catch basins and valley gutters, lining of 8” sanitary sewer and new street lighting for San Marino, DiLido and Rivo Alto Islands. In May of 2015 changes were made to the contract to include the new drainage design criteria adopted by the City. Due to the advanced stage of the construction, road raising was not considered for this project. In February of 2016 six (6) new storm water pump stations, including water quality structures, were added to the project. Currently, the three Venetian Islands have a fully operational pumped storm water system, new water main system, a lined sanitary sewer system, and new street lights.
LOWER NORTH BAY ROAD
The Lower North Bay Road Neighborhood Improvement Project began construction in September of 2014. The project included replacement of a gravity-based storm drainage system with a new, higher capacity collection and pump station system. The project scope included lining of the existing sanitary sewer system and the installation of a new water main and water services. The project also included roadway restoration and resurfacing but did not include road raising. A separate and subsequent project added new decorative street lights.
SUNSET HARBOUR
The Sunset Harbour Neighborhood Improvement Project commenced construction in May 2013. The original scope of work included improvements to the existing drainage system which was composed of drainage wells. In May 2014, the project scope was extended to include a new storm water system comprised of pump station and major trunk lines. In addition, new sidewalks, lighting and landscaping.
The average existing elevation was between 1 and 2 feet NAVD. Prior to the project, the roads in Sunset Harbour severely flooded during king tides. All roads within Sunset Harbour were raised an average of 2 to 3 feet.
One of the main challenges for this project was the harmonization. Private properties, adjacent to the right of way, were low and many of them were below sea level. As a result, some transitions from the road to the properties required encroachments into private property. It is important to note that this is the first project where the City had to request permission from property owners to transition from an elevated roadway into private property. This project started the discussions of harmonization and license agreements within the City. Consequently, current projects, such as West Avenue, are now better equipped to deal with these conditions during the design development.
ALTON ROAD
The construction of Alton Road between 5th Street and Dade Boulevard, an FDOT projects commenced in 2013. The project scope included total pavement reconstruction, installation of a new drainage conveyance system, installation of a new storm water pump station, and street furnishings including new sidewalk, lighting and landscaping.
The Alton Road project had significant constraints due to the proximity of the buildings and high groundwater table. As a result, road raising was minimized to mitigate the impact to adjacent properties. In addition, due to the high-water table, FDOT had to use full depth asphalt as opposed to the conventional limerock base with an asphalt top layer.
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| | | | | | | | ANALYSIS:
| During the September 11, 2019 City Commission meeting, staff was tasked with reviewing the impact of road raising on project duration and associated incremental costs. Due to significant variability in project scope, these impacts are not identifiable with an acceptable degree of certainty. Contractors do not itemize costs or breakdown schedules in a manner that would allow staff to discern the incremental impacts from road raising. Additionally, there are large dissimilarities on how contractors perceive risk, which further amplify differences in project costs. For example, in our most recently bid project, Indian Creek Ph. II, we received seven bids with a price range from approximately $13 million to $26 million. These bids were received for what is an identical scope of work, and while there are some factors that contribute to the spread, we must consider that pricing reflects the contractor’s aversion or acceptance of risk. Further, the uniqueness of each project scope, unforeseen conditions, and resident engagement also make it unfeasible to generate a comparison or generalized impact assessment.
The impacts on private properties and actions required by property owners also vary. In the Palm and Hibiscus project, due to higher original roadway elevations, properties on the east side of the islands experienced less impact than properties on the west side of the islands. At Sunset Harbour the road raising impacted adjacent properties during construction, but the harmonized areas have promoted a lively business friendly neighborhood after the construction was completed. By comparison, the Venetian Islands and Lower North Bay Road projects did not raise roads; nonetheless impacts to residents cannot be discounted as construction activities and duration affected their access and quality of life. Overall, it can be presumed, that lower properties will require more extensive harmonization efforts that may include driveway restoration, private property inlets, private landscaping within the right-of-way, or gates and fences which will need to be re-done.
Road raising, within the Palm and Hibiscus Island project and the Sunset Harbour Neighborhood Improvements, has proven to be an effective means to curb the effects of sea level rise and tidal flooding. Since the completion of the Sunset Harbour project, more than 60 tidal flooding events have been avoided. Similarly, road raising has helped the Palm and Hibiscus neighborhoods avoid flooding during king tides. The project team has no knowledge of any flooding events which have impacted habitable spaces for any of the residents on the Palm and Hibiscus islands. Recent monitoring of weather events has indicated that most of the properties have faired very well with localized ponding on low-lying properties, which will be resolved once the private inlet installations are complete.
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| | | | | | | | | Is this a "Residents Right to Know" item, pursuant to City Code Section 2-14? | | Does this item utilize G.O. Bond Funds? | | | Yes | | No | |
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| | | | | | | | Departments
| | Office of Capital Improvement Projects |
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