Ameren Illinois Rivers transmission line river crossings


Hanson is providing geotechnical, 结构, civil and hydraulic engineering services for Ameren Transmission Co. of Illinois’ Illinois Rivers transmission line. The transmission line crosses the Illinois River near Meredosia and Beardstown and the 密西西比州 River near Quincy. The project involves providing foundation designs and 访问 support for 14 lattice towers that reach as high as 460 feet and feature spans as wide as 3,700英尺. Foundation types included all-steel tripod foundations with driven H- and pipe piles as well as concrete pedestals with driven pipe piles.

"Hanson is a valued partner with Ameren and provides a very high-quality product." — Kevin Gerhardt, 阿莫林公司集团.

Hanson provided technical oversight and borehole logging for geotechnical investigations at each of the structure locations, 在某些情况下, advancing soil test borings to rock 120 feet below the surface. Hanson performed soil laboratory testing, land and bathymetric surveying and engineering analysis of design load cases, geotechnical parameters and hydraulic aspects of the river crossings to develop foundation design parameters and performance criteria (strength and displacement) for the evaluated conditions. These conditions included flood levels, scour and debris, hydraulic and ice forces.

Two foundation types were chosen to efficiently adapt to the unique conditions at each of the three crossings. The all-steel tripods were chosen as one of the types to eliminate the need for delivering or producing concrete for the foundations located on islands in the river. The tripod and pile combination also reduced wetland impacts in sensitive areas.

Civil engineering services involved the design of construction 访问 to each of the river crossing tower locations. At the 密西西比州 River crossing — the Herleman to Maywood river crossing — Hanson designed and permitted a 200-foot temporary riprap causeway from the main channel of the river to an existing sand bar. The causeway provided for the unloading of construction equipment and materials from barges onto the island that one of the transmission line towers is now located. The design necessitated obtaining a floodway construction permit, or “No-Rise” certification from the Illinois Department of Natural Resources’ Office of Water Resources. 申请许可证, Hanson had to demonstrate that the causeway construction would not cause an increase in the water surface elevation of greater than 0.01脚.

All three river crossings are complete and carrying high voltage electricity, increasing the capacity and strengthening the resiliency of the nation's crucial electric grid. Each location offered significant and unique challenges in permitting, 访问, subsurface conditions and the varying and often unpredictable river levels.

A technical paper co-authored by Ameren and Hanson personnel was included in the 2015 ASCE Electrical Transmission & Substations Structures Conference Proceedings: