The Nettle Creek Aqueduct was awarded the Outstanding Civil Engineering Award in the Less Than $10M category from the American Society of Civil Engineers Illinois Section. This project resulted in a widened aqueduct opening, increased resiliency against storms, improved trail systems and restoration of the pond at Gebhard Woods.
EXP led structural, hydraulics, surveying, civil, site and public involvement services for this project. An aqueduct at the intersection of the Illinois and Michigan (I&M) Canal and Nettle Creek has existed since the mid-1840s and has been reconstructed several times over the years. The most recent version was a single span structure with an arch feature; however, the arches were decorative and meant to support secondary walkways rather than the main load-carrying mechanism. In 2013, a flood caused its partial collapse and most of the aqueduct had to be removed.
“EXP’s team partnered with the consulting parties and the contractor to plan, design and construct a historically appropriate replacement aqueduct that will stand the test of time,” EXP Vice President, Transportation Brian Umbright, PE, SE said. “Reconnecting the I&M Canal and trail network was greatly appreciated by the local community.”
EXP evaluated restoration or replacement of the aqueduct while considering its historical significance. The team also had to consider maintaining the existing I&M Canal waterway prism, towpath along the north side and pedestrian path along the south side. Based on topographic and hydraulic surveys, geotechnical investigations, material sampling and testing and underwater inspection, EXP selected replacement as the best option.
The team prepared a schematic design submittal that proposed replacement aqueduct options. The result was a single span structure with an arch-like façade. The opening of the aqueduct was also widened from 45 to 140 feet in order to decrease hydraulic jump, which occurs when water at high velocity abruptly slows, causing water to rise quickly. This change increases the structure’s ability to withstand storms.
Learn more about EXP’s water expertise.