Davis, I am neither a ...

Davis, I am neither a structural nor a civil engineer, but the secant pile wall system seems like a viable solution and limiting exposure to contaminants may come down to the actual construction sequence with proper Personal Protection Equipment (PPE). Another option may be a "Tilt-up" sytem where walls are poured like slabs on site close to final destination and then craned into place. In this case, a water proofing liner could be installed or applied while the wall is horizontal with the edges being sealed once in place. Just a thought.