Special Applications Artistic Merit

Location: 486 228th Ave. S.E., Sammamish

Owner/developer: City of Sammamish

Project team: Thomco Construction, general contractor; Turnstone Construction, concrete contractor; Gray & Osborne, structural engineer; Johnson Western Gunite Co., ready-mix supplier

The city of Sammamish decided to replicate natural rock formations on two retaining walls that were needed to widen the 228th Avenue Southeast corridor.

The finished prouduct looks like natural rock.

One of the walls is 720 feet long and about 10 feet tall while the other is 150 feet long and up to 20 feet tall.

The walls were constructed in three phases. First, crews erected soldier pile walls and shotcreted the surfaces. T

hen they carved and smoothed the concrete, adding seams, crevices and texture. The final step was staining the walls to mimic color variations found in nature.