Reinforced soil walls maximizing urban developable land

Overview

Creating stable development platforms on constrained urban sites often comes down to one question: how to retain soil efficiently without giving up valuable land. At Eco Botanic City in Iskandar Puteri, Johor, land formation required long, steep retaining structures capable of supporting residential and mixed-use development while adapting to varied topography. Conventional retaining systems would have consumed space and increased material demands. A reinforced soil wall solution offered a way to form safe, buildable platforms while maximizing usable land and maintaining constructability.

The project involved approximately 1,385 m of geocomposite-reinforced soil walls with heights ranging from 2.0 m to 7.0 m using MIRAFI^® Polyfelt PEC. Wall faces were constructed at an inclination of roughly 82 degrees from horizontal, with selected sections incorporating backslopes of 0.5 m to 3.0 m at a 1V:2H gradient. The system was designed to accommodate site geometry, support long continuous wall alignments, and align with sustainable urban development goals.

Challenge

The primary challenge was delivering a structurally sound retaining system across a long alignment with variable wall heights and integrated backslopes, all while maintaining construction efficiency and land-use optimization. The walls needed to perform as permanent structures, resist earth pressures, and manage internal drainage without relying on imported or specialized backfill materials.

Construction sequencing also required tight control. Reinforcement layers had to be installed at consistent vertical spacing, backfill needed to meet compaction requirements, and drainage elements had to remain continuous along the full wall length. Any inefficiency or material incompatibility would have increased construction time, cost, and environmental impact through additional material transport.

Solution

A geocomposite-reinforced soil wall system was selected for its flexibility, cost efficiency, and ability to use locally available backfill. Composite reinforcement geotextiles were installed at 0.4 m vertical intervals, working in combination with segmental block facing units. Backfill was placed in 200 mm lifts and compacted to at least 95% of maximum dry density, forming a stable reinforced soil mass behind the facing.

MIRAFI Polyfelt PEC composite geotextile was used as the primary reinforcement and separation layer. By combining multiple functions into a single product, the system simplified installation and reduced the number of materials handled on site. Internal drainage was managed using drainage aggregates, subsoil pipes, and MIRAFI Polyfelt TS nonwoven geotextile for filtration, ensuring controlled water movement and long-term performance of the reinforced structure.

The completed walls provided stable development platforms while reducing material transport and supporting the use of on-site soils, lowering the project’s overall carbon footprint. The outcome demonstrated that long, high reinforced soil walls can be constructed efficiently using composite geotextiles when proper design standards and construction controls are applied. The solution delivered durable earth retention, optimized land use, and a practical framework for sustainable urban site development.