When the mayor of San Francisco, state legislators, city councilors, and 20 to 30 other dignitaries gather together for a building event, you figure it’s a high-profile groundbreaking or ribbon-cutting ceremony – not a technical presentation of a below-grade waterproofing solution.

Such are the sky-high stakes surrounding the $4.185 billion “Grand Central Station of the West,” the mammoth new Transbay Transit Center now under construction in downtown San Francisco.

“We literally had 20 to 30 people standing over my shoulder as we presented mock-ups of our alternative waterproofing solution, from the mayor on down,” explains Dean Edwards, project lead for Gardena, Calf.-based Best Contracting Services, Inc., the waterproofing subcontractor on the project.

The officials had good reason to be concerned. The gargantuan project had fallen up to two and half months behind schedule. Chief among the challenges: a waterproofing method “… that was taking forever to cure” in the damp, deep immensity of a four block-long excavation. The budget clock was ticking, costly labor waiting, and water extraction pumps thundering 24x7.

At issue was the original asphalt-based fabric solution. It wasn’t curing as predicted due to jobsite conditions. A better solution was needed immediately and had to work: the application of Preprufe® waterproofing membrane.

“We brought Grace to the table,” Edwards states. “We explained that Preprufe is a pre-applied, zero-cure waterproofing membrane. No wait and proven across hundreds of major infrastructure projects over the past 20+ years. What’s more, I believe in it. By taking curing off the table, we knew we could expedite the schedule.”

The hydraulic forces compressing the worksite on all sides were incredible. If the pumps stopped even briefly, the walls started to immediately weep. “We were at least 30 feet below the water table. By being so close to San Francisco Bay, you can guess the stresses at work,” Edwards said.

Minutes mattered. California’s acute construction labor shortage only compounded the pressure to perform. Rodbusters and other trades had schedules to meet.

Edwards knew he could count on Preprufe [waterproofing membrane]. No other product can claim the worldwide acceptance of Preprufe, with more than 500 million square feet installed across hundreds of high-profile public and private projects worldwide. Preprufe [waterproofing membrane] is designed to deliver exactly what the GC (Webcor Builders and Obayashi Corporation) and army of waiting subs needed, with:

  • Fast, easy and straightforward installation
  • A robust product design able to withstand the rainy and predictably bad San Francisco weather
  • Permanent adhesive bonding of the strong HDPE barrier to the concrete
  • A clean, neat, asphalt- and clay-free product that is highly resistant to contaminated and aggressive soils
  • Immediately trafficable with same-day rebar setting and tying.

The Best Contracting teams set to work, sealing-off the walls and floor. With cure times off the table, installation proceeded swiftly.

Delivery of the first phase of the project is scheduled for 2017. Today the news is all good: “The jobsite is dry. We’ve been actually waiting on the general contractor to catch up with us,” Edwards is pleased to say.

“Working with Grace is peace of mind. They’re there for us to develop new details to install a warranted system confidently. They’re the gold standard of the business.

“From a contractor standpoint, I couldn’t ask for anything better.”