Three's a Crowd-Pleaser

Over three days this past week, workers at the Kraken Training Center took three giant steps toward Seattle skaters stepping on the ice this fall. On Tuesday through Thursday, concrete was poured to form the bases for three NHL-regulation size rinks, 200 by 85 feet.
"We've been really busy the last six months trying to get a shell on this place," said Alex D'Avella, project manager for BNB Builders, which is the general contractor for the Northgate training center the Kraken and Pacific Northwest community will call home base for hockey, figure skating, power skating, public skating, curling, broomball, community events and lots more. "Getting windows in, siding, the roof. Seattle can get a little rainy [in the winter months]. Now, getting the ice slabs in."

D'Avella was standing in an overlook room to Rink 1 last Wednesday as "power screeds" (that sort of look like mini-Zambonis if you use your imagination) were finishing the surface of the concrete slab upon which ice will be installed in just a few can't-wait months. Rink 2 concrete was poured and smoothed Tuesday while Rink 3 was pumped into place Thursday.
Rink 1 is the Kraken's practice rink (and will be used by the community when the team doesn't need it). Rinks 2 and 3 will be hosting a many-splendored and inclusive set of activities.
Each ice-slab pour required roughly 340 cubic yards of concrete with trucks arriving by 5:30 a.m. each day and trucks arriving every 10 minutes or so. D'Avella says "it's a feat" to get one rink slab poured in a day and a feat and then-some to do three slabs in three days.

"I've spent a lot of time in hockey rinks [as a kid and adult growing up in Massachusetts] but I never really thought about how the ice was made," said D'Avella. "Just thought it was really cold buildings."
Quite the contrary, there are different layers of piping and insulation-including one deep-ground layer--stay with me now--that keeps the pipes that freeze the rink's water from getting frozen at the wrong times.
Twelve to 13 miles of piping goes into each rink before the concrete is poured via a 200-foot-long concrete pump line and buries the piping that will freeze the concrete evenly and cold enough to create perfect ice. Thirty workers worked long days to achieve that base for perfection.
"There is no construction joint [partitioned segments]," said Neal Schaefer, senior superintendent for BNB Builders. "It's one continuous pour. It cannot go wrong. So we have back pumps, backup robots, backup everything.
"One particular challenge is consistent ice [over the entire 200-foot-by 85 sheet]. We can't be three-quarter inch deep at one point and an inch-and-a-half somewhere. It can't just look pretty, it has to be functional."

A worry-wort question: Once the concrete sets, you can't fix any inch of that 12 to 13 miles of piping. How do you know there are no leaks when you are pouring.
Schaefer answered that crews have been testing the pressure of the piping throughout installation, running 50 PSI test pressure with a gauge in the ice plant room (which will control all three rinks) showing if any leaks or issues.
The testing continued during the concrete pours and finishing to make sure nothing was marred during the concrete pumping and screeding. In fact, that pressure-testing would have created a "loud audible sound" if any leaks were discovered, setting off a literal alarm to fix the leak.
Those mini-Zambonis (OK, right, power screeds) use one type of blade to do the magical job of uniformly smoothing and leveling the ice slab surface. Schaefer said the final step is changing out the blade for one that "burns" or creates a "hard-trowel" finish that you know is when the top layer "shines like glass."
"The last step condensing the surface layer to bring up the cream and fine sand," said Schaefer. "It is small-aggregate and keeps the 'rocks' of concrete lower down. Then later in the day we test for overall flatness. We tested Rink 2 [Tuesday] and it was off-the-charts for levelness and super flat."