To expand and upgrade operations at the Stickney Water Reclamation Plant, Stalworth Underground was contracted to provide five earth retention systems, modify an existing earth retention system, and install the driven pile and micropile foundation systems on the site. Sheet pile walls, a soldier pile and lagging wall, cantilevered walls, walls braced with tiebacks (4 deadman anchors and 50 tiebacks were installed), and walls braced internally (corner braces, struts, and rakers) were used. Retained heights varied from 12 to 20 feet and the project required deflection to be limited to 0.25 inches. Designing a cost-efficient but effective wall meeting the deflection requirement was particularly challenging, as in some areas the walls has surcharge loads as high as 4,500 psf!

In addition to earth retention systems, micropiles were installed inside an existing structure to stabilize the foundation. For half the piles, the micropiles were installed from inside the structure utilizing a low clearance drill. We also performed a micropile load test prior to construction to verify the micropile design met the requirements.

1,800 deep foundation piles were installed, including 1,360 piles were installed within an existing building footprint. This was particularly challenging as pile locations had to be thoroughly coordinated with the surveyor and the engineer to ensure obstacles weren’t encountered during installation. Prior to installation of production piles, five compression load tests and two lateral load tests were performed. Soil on site varied greatly and pile lengths did as well.