Forensic Investigation / Waterproofing
San Francisco, California
DLR Group|Kwan Henmi
In 2016, BART successfully completed an extensive remedial waterproofing project at the concrete ceiling of the Mezzanine Level of the Powell Street BART Station. Tom Butt of Interactive Resources was the project architect contracted as a subconsultant to the prime consultant to BART, Kwan Henmi. Pullman SST, Inc., was the general contractor.
Interactive Resources had been working on this project periodically since 2007 and had conducted extensive research and testing before settling on the optimum products and methods for the waterproofing. Most of the ceiling areas were injected with a hydrophobic urethane grout, and other smaller areas were waterproofed with a urethane traffic coating or a crystalline waterproofing system. There were many challenges. The failed original waterproofing system was on the outside of the concrete ceiling and inaccessible for any direct observation, removal or replacement. Concrete ceiling temperatures were as high as 170° F in some locations from a 350° F steam pipe running above the ceiling. Multiple concrete spalls had to be repaired and special coatings applied to encapsulate some previously tested, but failed waterproofing injection grout products. Much of the work had to be done between midnight and 4:00 AM when the BART station was closed.
Interactive Resources also evaluated and diagnosed the cause of failed metal brackets on the Station’s escalators. We also provided structural engineering services for the 19th Street BART entrance canopy.