MARYSVILLE — The ongoing replacement of the State Route 529 Ebey Slough Bridge has seen some significant milestones since this winter, and if the weather permits, March 8-11 will mark yet another key step toward the completion of the nearly three-year construction project.

“We’ve completely demolished the existing bridge structure, well below the ground line, to the point that no remnants are visible,” said Joe Rooney, chief inspector for the project with the Washington State Department of Transportation. “Once that was complete, we were able to build the approach fills on the west side of the new bridge, which put us in place to pave the full width, not including the final overlay we’ll be doing in April.”

According to Rooney, so long as the construction work doesn’t get rained out, SR 529 is set to be closed from First Avenue to Milepost 6, including the Ebey Slough Bridge, starting at 8 p.m. on Friday, March 8, and lasting until 5 a.m. on Monday, March 11.

“We’ll finally be pulling out that temporary barrier to put in temporary striping along where the permanent channels will be,” Rooney said. “The plastic imprinted striping will go in place this spring, but the new bridge will be at full capacity for the first time. With a little bit of landscaping work left, we should be completely out of here by May.”

Rooney noted that the original construction timeline afforded WSDOT and its contractor, Granite Construction, well into the summer months to wrap up their work, so they’re ahead of schedule and well within their budget.

“We’ve just been extremely fortunate,” Rooney said. “There haven’t been any significant change orders or design errors or surprising site conditions, and when you’re working that far under the surface, who knows beforehand what you can find. Granite Construction have been great partners as well.”

The project typically employed between 50-60 personnel on site, between subcontractors and specialists in fields such as pile-driving stone columns into the ground to form the supports for the new bridge.

“We built the new bridge well before we demolished the old one, which allowed us to keep traffic flowing throughout construction,” Rooney said. “We also benefitted from replacing a two-lane bridge with a four-lane bridge, so we were able to set up the two lanes on the west side of the new bridge as a staging area for construction without reducing the existing traffic capacity of the bridge. People had two lanes of traffic on the old bridge, and they’ve had two lanes of traffic on the new bridge, so they haven’t seen much difference yet.”

Rooney acknowledged the challenges of demolishing an old bridge directly over a waterway in an ecologically conscious fashion, so as not to contaminate the surrounding wetlands.

“We couldn’t have any debris at all, which is pretty difficult when you’re taking out a 700-foot-long span,” Rooney said. “To their credit, Granite Construction took this task seriously, and still managed to take out the existing structure to 10 feet below the mud line.”

Rooney reiterated that the scheduled closure of the SR 529 Ebey Slough Bridge from 8 p.m. on Friday, March 8, until 5 a.m. on Monday, March 11, is entirely weather-dependent, so check the WSDOT site at www.wsdot.com/traffic/seattle/default.aspx?op=/traffic/seattle for the latest information.