One of the best parts of working in the geotechnical world of construction is the unique and challenging projects we build. Our job in St. Joseph was one of those jobs.
The City of St. Joseph formed a multi-year strategic plan for updating its drinking water system. One of the first phases of the plan includes creation of a new pump station, which will pump water to be filtrated for safe consumption. Our portion of the work happened during this phase. A drilled H-pile and wood lagging wall spans 180 lineal feet with a 24 foot cut. Within the barrier of the lagged wall, a secant wall was also constructed.
Secant walls are a type of earth retention system that creates a water tight barrier. This is accomplished by drilling overlapped concrete piles, with a reinforcing steel beam placed in every other pile. A treme seal is then poured at the bottom of the wall, ensuring no groundwater can enter the area. The secant wall for this project ended up being 45' x 15', 25' feet deep, and included a 5' treme seal. The total project ended up lasting approximately 3.5 months and was done in two phases, each wall type being one of the phases.
Being less than 100 feet from Lake Michigan gave the crew some pretty great views while working, but the close proximity to the lake also ended up throwing them some major challenges. First, the bottom depth of the secant wall was drilled to 15' below Lake Michigan water elevation. The drilled depth coupled with the close proximity to a large body of water made for constant water issues on the job site. The ground water problem is the main reason the secant wall was installed versus other earth retention systems. Additionally, the job ran from November-February. The brutal cold and gales off Lake Michigan made for some very harsh working conditions. Even with unfavorable conditions and tight timeline, the crew overcame them and produced high quality products.
The project was another successful secant wall installation for the HCI team. Successfully implementing techniques and technology is not only rewarding, but it is also exciting to expand the scope of work and open potential new markets for Hardman Construction.
Kudos to our crews who met the challenge head-on with a positive "can-do" attitude!