Taller Retaining Walls

Skyline Ridge’s 17 tall Allan Block walls were expertly designed and constructed, highlighting the importance of stability, communication, and quality control in large retaining wall projects.

Attention to Detail is Key When Building Taller Retaining Walls

The Skyline Ridge Development, a 90-unit luxury condominium community in Springfield, New Jersey, was built on a steep and hilly site with limited buildable space. To create usable construction plateaus and maximize the views of the Manhattan skyline, a series of large Allan Block walls were designed and built. The project features 17 Allan Block walls, over 75,000 AB Classic blocks, and a maximum grade change of 70 ft (21.3 m).

Analyzing Global Stability

Tall retaining walls like those at Skyline Ridge require thorough design analysis and continuous inspection during construction to ensure soil stability and wall performance. Porcello Engineering of Pine Brook, New Jersey, used AB Walls Design Software to design the individual walls and ReSSA to analyze the global stability of the terraces and the overall site.

These walls were engineered not only to support parking and recreational areas but also to support the building structures founded on spread footings directly above the walls’ reinforced soil mass. Minimizing future settlement was therefore a top priority. Fortunately, the site’s granular soils provided excellent support for both design and construction.

To streamline construction, Porcello and the general contractor held a preconstruction meeting to align all parties and establish a practical schedule. Weekly site meetings ensured ongoing communication regarding progress and construction quality. An on-site soils engineer monitored soil quality and compaction, and detailed inspection logs were reviewed at each meeting, supporting a smooth and efficient construction process.

For more on Skyline Ridge and other Allan Block projects, visit the case study section of our website or follow Allan Block on LinkedIn for technical updates and discussions.

Communication is Critical for Successful Wall Projects

Building large retaining walls requires more than equipment and installation skills. While the crews from Pillari LLC. are AB Certified Installers, effective communication among all parties is equally important.

At Skyline Ridge, project success began with a preconstruction meeting and continued with regularly scheduled construction meetings. These gatherings ensure alignment and coordination, especially for large walls, though the principles apply to all wall projects.

Who Should Attend Preconstruction Meetings?

• Owner or Owner’s Representative
• Site Engineer
• Wall Designer
• Geotechnical and Testing Engineers
• General Contractor
• Wall Installer
• Other Subcontractors (utilities, irrigation, paving, landscaping, etc.)

The meetings should address:

• Project schedule and costs
• Wall design review and compliance with site drawings
• Verification of site soils
• Water management during and after construction
• Material staging and delivery schedule
• Responsibilities and testing requirements

Ongoing construction meetings help solve potential issues, maintain project schedules, and keep costs in line through consistent communication among the site engineer, wall designer, general contractor, and wall installer.

Special Considerations When Designing Taller Walls

Designing a wall system like Skyline Ridge can be complex. Success is measured not only by completing the wall safely, on time, and within budget but also by its long-term performance—especially when structures are built atop the wall system. Key considerations for tall walls include:

• Bench Cutting the Slope – Create benches along long slopes to prevent slip surfaces behind the wall.
• Qualified Contractors – Specify minimum experience and AB certification for contractors.
• Detailed Plan Review – Examine site geometry and structures above and below the wall to resolve conflicts.
• Water Management – Implement a comprehensive plan for above- and below-grade drainage, storm drains, curbs, gutters, and utilities.
• Increased Compaction – Compact soil beyond 95% Standard Proctor to minimize settlement.
• Onsite Inspection – Require detailed inspection logs signed off incrementally and retained in project records.
• Select Fill – Use imported, compactable sandy gravel with a plasticity index (PI) of zero for the bottom portion of the wall’s reinforced soil mass.

Keeping these points in mind during the preparation of construction documents will help ensure a safe, stable, and successful tall wall project. For guidance on tall wall design or to request your AB Walls Software Tall Wall Password, contact the Allan Block Engineering Department at (800) 899-5309 or engineering@allanblock.com.