D-9 Canal Gabion Basket Design

Port St. Lucie, Florida

D-9 Canal Gabion Basket Design – City of Port St. Lucie, Florida
D-9 Canal Gabion Basket Design – City of Port St. Lucie, Florida

Project Scope

The D-9 Canal, stretching 1.32 miles through a residential neighborhood in Port St. Lucie, had long been a source of concern for city officials and residents. With steep banks and ongoing erosion, maintenance was difficult and, in many areas, impossible. The canal is constrained within a narrow 50-foot-wide drainage right-of-way, flanked by single-family homes on both sides.

The City of Port St. Lucie needed an innovative, cost-effective solution that could meet slope requirements without exceeding the available footprint—and stretch limited grant funding to its fullest potential.

Scope of Work
Haley Ward, Inc. was brought in to deliver a thoughtful and resourceful redesign, which included:

  • Civil engineering design of canal cross sections
  • Cost analysis and value engineering
  • Coordination with surveyors to obtain detailed topographic data
  • Drainage and stormwater design enhancements
  • Development of custom wedge drain details
  • Construction plan preparation and coordination

Design Approach and Challenges
The city required canal side slopes not to exceed a 3:1 ratio, but the site’s vertical differences—up to 10 feet in some areas—would not allow this within the given constraints. Traditional piping was initially considered, but our team identified that using gabion baskets would provide substantial savings and be more suitable for the setting.

Gabion baskets offered flexibility in height and placement, allowing us to:

  • Stack baskets in double-height configurations to accommodate nearly 6 feet of elevation difference
  • Create stable canal slopes while maintaining the required hydraulic capacity
  • Reduce erosion and improve long-term maintainability

In areas with poor soil quality, wedge drains were designed to improve subsurface drainage. This involved excavating unsuitable material to a depth of about one foot, replacing it with six inches of stone and six inches of soil to help direct water to the back of the gabion structure, preventing buildup and ensuring long-term durability.

Our solution saved the city and federal government nearly 50% compared to traditional piping. While piping the canal would have cost approximately $4.5–5 million, the gabion design came in around $2.5 million.

The final design met the city’s engineering and environmental standards while reducing long-term maintenance burdens and eliminating the need for specialized mowing equipment to navigate steep banks in residents’ backyards.

Market

Services

  • Civil engineering design of canal cross sections
  • Cost analysis and value engineering
  • Coordination with surveyors to obtain detailed topographic data
  • Drainage and stormwater design enhancements
  • Development of custom wedge drain details
  • Construction plan preparation and coordination

Project Data

Redesigned 1.32 miles of the D-9 Canal with new cross sections and stormwater upgrades. Fit the improvements within a tight 50-foot ROW while addressing steep grade and erosion issues.
Implemented gabion basket stabilization instead of traditional piping. Maintained hydraulic capacity and reduced projected costs nearly 50% compared to piping.
Added custom wedge drains with coordinated topographic surveying. Improved subsurface drainage and lowered long-term maintenance needs.