Helical Tieback Installation in Seattle, WA

Structural Repair Solutions in Washington

The Problem

After arriving on site, Matvey Construction found a 250 by 8 foot ten year old retaining wall that was 6 inches out of level. There was zero drain rock, no footing drain, and very poor structural fill. The hill below was a series of residential homes, and it was a 400 foot drop to the Puget Sound.

The first thing to do was soil probing. Then, a series of soil borings were completed. After this, it was concluded that the solution would be helical tiebacks and push piers.

The Solution

In order to fix this problem, complete soil density testing needed to be done. The client was then supplied with a structural repair design permit set. A concrete saw cut 10-inch holes, and the 10-inch by 8-inch helical lead sections were installed.

The next step was to install steel plates with a 6-inch c-channel over lay. Thin set and water seal wall borings were then installed. Complete load tests were performed on each individual tie-back. The push piers were installed with a minimum 8-kip capacity. The wall was level and plum. Finally, movement monitors were installed and a 24-month chart was used to evaluate how well the installation will hold up years down the road.

The Results

Two years later, there was zero movement as reported by geo-tech tracking the site. The wall was still perfectly level and plum.

Other Case Studies

Drainage System Installation
Helical Pier Installation
Push Pier Installation