Mission Rock

A new waterfront neighborhood is coming to San Francisco, CA across from the AT&T Stadium. The location of this development site poses unique engineering challenges, one of the most pressing issues is protecting the site against Sea Level Rise (SLR). The proposed design needs to meet the recommended elevations of the ResilientSF plan, the City of San Francisco’s strategic plan to improve construction standards and strengthen the community.

The first phase of this project requires building lightweight cellular concrete (LCC) gravity walls along the perimeter of our pour site. Cellular concrete gravity walls were incorporated in the design to help construction crews work simultaneously without conflict and prevent schedule delays. The LCC gravity retaining walls will resist lateral pressure produced by heavy equipment and materials on adjacent pads, allowing for safe excavation and construction of utilities in the streets.

In the second phase, lightweight cellular concrete backfill will raise grade elevation of the streets and limit consolidation settlement. We poured 27 and 30 PCF LCC to raise the site 5 ½ ft. If the site were raised by placing traditional soil fill, then the weight would cause predicted settlement of up to 22 inches. The result would be non-functioning infrastructure, including slopes in paving, poor drainage and damage to underground utilities. Cellular concrete was also chosen because it meets all the required performance goals required for the projects backfill material: high bearing capacity of heavy loads, excavatable for utility maintenance and favorable earthquake performance.