I-95 Interchange 74 Improvements

GeoEngineers’ Construction Design team partnered with K2 Infrastructure Group to design SOE, dewatering, and water handling systems for multiple excavation sites at the I-95 Interchange 74 Improvements and Bridge No. 00250 Replacement project in East Lyme, Connecticut. The project involved constructing new retaining walls, culverts, and bridges to reconfigure Interchange 74 of I-95. GeoEngineers’ designs ensured safe, efficient excavation and water management throughout the complex highway and bridge construction.

Approach

• Designed SOE at thirteen locations, including eleven retaining walls along the new I-95 alignment and two culvert endwalls, using slide rail systems for precast Doublewal units up to 12 feet tall and soil nails for a 25-foot wall.
• Developed dewatering systems for each retaining wall excavation using evenly spaced sump pits.
• Designed phased water handling systems at two culverts with stacked sandbag cofferdams to maintain flow during reconstruction.
• Value-engineered Retaining Wall 116 using drilled micropiles and cast-in-place facing to replace the original design, addressing driveway access, adjacent utilities, construction sequencing, and aesthetics.
• Managed challenges including variable site conditions, traffic phasing, and interfacing with existing structures.

Results

GeoEngineers delivered comprehensive design calculations and detailed construction drawings for SOE, dewatering, and water handling systems across the project site. The package included plans, cross sections, bracing configurations, and material specifications, as well as value-engineered details for Retaining Wall 116. These deliverables guided the contractor in safely and efficiently constructing walls, culverts, and water management systems while accommodating traffic phasing, adjacent utilities, and site-specific constraints, ensuring the successful progression of the I-95 interchange improvements.