Overcoming soft soil challenges with MIRAFI

june 2024

2 Min read

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MIRAFI® Geotextiles
MIRAFI® RSi Series
Site development

Overcoming soft soil challenges with MIRAFI


The East Lake Sammamish Trail (ELST) is a scenic, 11 mi (about 17.7 km) long recreational trail located along the eastern shore of Lake Sammamish. Originally following a historic railroad route, this paved path is designated for non-motorized travel. It connects various neighborhoods, retail centers, parks, and transit options, enhancing local connectivity.


The development of ELST involved phased construction, with each section presenting unique challenges. The Issaquah segment, in particular, was costly, totaling $2.74 million. This expense was primarily due to the trail's narrow layout, which necessitated a full closure for the transportation of construction materials. 

During construction, a stable working platform was essential. To overcome the challenge of soft soils, the construction team used MIRAFI® RS580i, a high-strength geosynthetic material, coupled with 12-18 in (30-46 cm) of crushed rock. Solmax provided 15 ft (4.6 m) and 17 ft (5.2 m) wide rolls of MIRAFI RS580i, reducing material overlap and waste, thereby minimizing costs. 


The choice of MIRAFI RS580i proved advantageous due to its ease of use and ability to remain stable during construction. Its exceptional damage resistance offered superior durability compared to other geosynthetic products. The wider rolls of MIRAFI RS580i also contributed to reduced material waste and less overlap. Its high modulus, friction, and permittivity enabled the stabilization of saturated subgrades using thinner aggregate layers than traditional methods. This approach led to significant cost and time savings for the project. Additionally, MIRAFI RS580i serves as a lasting separator between the fine-grained, saturated soils and the clean aggregate layer above, ensuring long-term stability.