INNOVATION November-December 2012

f ea t u r e s

One day while drilling they discovered chlorinated solvents in the groundwater over 13 metres below the bottom of the Fraser River bed, contaminants that weren’t supposed to be there. “That’s when things started going sideways,” says Kullmann in his charac- teristically understated way. His company, with expertise and experience in integrating waterfront engineering and remediation, considered more than 10 different options to deal with the solvents, including conventional sheet piling and excavating. However, the dense soil, underground obstacles (over the years the shoreline was extended into the river with boulders and fill) and active rail lines nearby precluded all but one: a jet grout/bentonite wall. Widely used to stabilize holes during construction of high-rise buildings, jet-grouting to contain contaminants is an innovative use of the technology. “We had difficulty getting the jet grout columns in place, but ultimately it was the right approach because we were able to make it work,” says Kullmann of the successful installation of a 22-metre long wall into a layer of clay and silt, one of the deep- est jet grout walls ever constructed in Canada. To confirm that it worked, the company used precision instru- mentation not commonly used in North America that had to be air-freighted from France. This “verticality tool” allowed confirma- tion of the grout column positions over their entire length, provid- ing quality control on the integrity of the system. Unfortunately, one such tool was lost in the debris deep inside one of the columns and they had to rush a second one to the site from Europe. Yet another innovative solution was called for during seismic ground densification work. The ground beneath the yet-to-be-built concession had to be stabilized, but when work crews tried driv- ing timber piles into the ground they kept disintegrating. During earlier soil investigation nothing suggested the fill on the site “was largely junk” says Kullmann. “We missed all the boulders in that area, but when you’re putting three thousand timber piles in, you’re going to find whatever debris is in the ground.” Analyses completed by Exp Services, the geotechnical engineers on the project, showed that enough piles were in the ground to take care of seismic issues, but now the building was expected to have unacceptable differential settlement from missing a large number of adjacent piles. The solution, “on the fly” according to Kullmann, was to lighten the load by eliminating the three to four metres of fill behind the building. “So we took the gravel out and put expanded polystyrene in,” is how he puts it. Polystyrene is much more expen- sive than gravel, but useful when poor soil conditions can’t bear the weight. A leveling slab inside the building took care of what little settlement did occur. By far the worst point in the project was the early part of 2011, says Kullmann. “We had the landscape contractors starting their work at the same time as the jet grouting was being done and the pile driving was still underway, so it was pretty tight. And, at the same time we were doing drilling.” A Winning Result If it sounds like a busy two years, Kullmann agrees it was, with “constant communication, constant updates on construction so that one contractor [wasn’t] stepping on the toes of the other contractors,” adding that “everybody stepped up to the plate to make it work.” The director of engineering services for the City of New Westminster, Jim Lowrie EngL, says the staff of WorleyParsons deserves much of the credit. “As lead consultant, WorleyParsons

Part of that two months included public consultation. “They had an idea they were going to build a park, but really had no idea what that was going to look like,” says Kullmann. Adds Gibson: “We really expedited all the processes right from what I would call the public engagement and consultation to help inform the overall design for the park. Ordinarily, for a site that size you might have public consultation that spans many, many months, if not years before you actually begin construction. We did that in a much more consoli- dated timeframe, with a lot of concentrated work.” Unpleasant Surprises Had the only challenges been the tight timeframe and the physical constraints of the property—it’s just 30 metres wide at its widest part and over 600 metres long, with access only at one end—the story might not be quite so interesting. Instead, an unexpected challenge popped up that added another layer of intrigue and complexity. A lot of environmental investigation had already been done on the site, explains Kullmann. “All we had to do was fill in the gaps and then complete the remediation” in order to get a certificate of compliance from the BC Ministry of Environment, one of the key objectives. Or so they thought. Top: The waterfront site for the project sat idle for some 20 years and was in want of attention. Below: More than 10,000 shrubs and trees were planted in the park, creating a “living wall” to block out traffic noise.

2 4

Nov e m b e r /D e c e m b e r 2 012

i n n o v a t i o n