Halff Associates, Inc.

Project Location: St. Pete Beach, Florida

Category: Environmental + Sustainability

Started: September 15, 2020

Completed: December 19, 2022

Project Team: 

Halff Associates, Inc.

Project Summary: Issues with sea level rise have been a pervasive issue for residents in the Don CeSar neighborhood of St. Pete Beach. The historic Don CeSar community developed in the 1920s is due east of the Don CeSar Hotel. The Little McPherson Bayou, a waterway within the greater Boca Ciega Bay, sits within the neighborhood and is less than 1,000 feet from the Gulf of Mexico. The Pinellas Bayway is north and northeast of the community. 

Homeowners enjoy beautiful views and have direct access to the water. However, residents are facing challenges associated with rising sea levels, frequently experiencing saltwater flooding of the streets during high tides, king tides and the convergence of tidal and storm conditions. Flooding events obstruct access to homes and damage vehicles. 

The City of St. Pete Beach is implementing a short-term plan to address these flooding challenges by closing culverts and sloped street ends that provide a conduit for saltwater to enter the neighborhood. Because the culverts and sloped street ends constitute the neighborhood’s only drainage infrastructure, this initial effort replaces them with larger culverts and backflow preventers to keep saltwater out of the streets. 

The City of St. Pete Beach retained the services of Halff Associates, Inc., to prepare an alternative that would allow the neighborhood to withstand a rise in sea level from approximately 2.5’ to 5’ NAVD 88 by 2050. 

The firm built a multi-disciplinary team uniting expertise in Public Works, Water Resources and Planning and Landscape Architecture. Tasks in the Adaptation Planning effort included:

  • field reconnaissance, 
  • the establishment of assumptions regarding sea level rise, 
  • flood mapping to form the basis for the design solutions proposed,
  • analysis of land use patterns and ownership, and 
  • identification of natural assets that could serve as part of the solution. 

A landscaped berm behind the seawall will preserve the area’s natural beauty while strengthening the neighborhood’s defenses at the perimeter with a two-tiered system to keep out saltwater. A conceptual plan reconfigures local streets and drainage infrastructure and channels excess rainfall to a detention area in Lazarillo Park to prevent stormwater from inundating neighborhood homes. By lowering the park’s elevation and retrofitting its facilities to withstand intermittent flooding, the neighborhood preserves the amenity while adding storage capacity for stormwater. 

An advanced pumping system returns stormwater to the Bay. Although this adaptation alternative may require changes in the neighborhood’s layout, this vision also offers opportunities to restore amenities and preserve livability over the next 30 years.