Project Summary:

Project: WSDOT SR 704 Cross Base Hwy. Noise Wall
Location: Spanaway Loop to SR 7- Spanaway, WA
General Contractor: Ceccanti, Inc.
Service Provided: Drilled piers and bolt assembly for Noise Wall
Number of Drilled Piers: 188
Drilled Depth: 8-13′
Pier Diameter: 30”

Project Overview:

This job began in mid-November 2008. There were 188 piers to drill at depths from 8-13 ft. It was scheduled for just over two weeks time to drill.

The Geotechnical report indicated a lesser size and amount of cobble than what was found on-site. The site consisted of large cobbles and pit-run, making the use of casing on every shaft a necessity. Casing is used because the large size of the cobbles would make the shaft walls cave in and in turn, would take more grout to fill the shaft, costing the customer more. The drawback is the casing procedure takes more time, slowing down the production rate of drilling, making the job take longer. Our lead foreman, implemented new tooling to enable the auger to lift out the large cobbles without them binding on the casing wall, thus making the drilling operation faster and more efficient.

During drilling operations, a mid-winter blast of freezing temperatures fell on the Seattle area making working conditions arduous. The grout in the drilled piers was subject to cracking and freezing and would not set up to meet the rigid standards of the WSDOT specs. We had to implement a warming method to allow the grout to set. We used a system of straw, plastic, lights, and blankets to keep the top of the pier warm and dry enough to be able to cure. Once cured, the top of the pier was to have a bolt assembly added so that it would receive the noise panels. A template was devised to use from pier to pier to keep the measurements precise. The tolerance was very narrow.