Engineering and Construction Details for the SCE Experimental Kelp Reef, San Clemente, California

Southern California Edison (SCE) plans to construct a 22.4 acre experimental kelp reef from hard substrate materials placed over a natural sandy bottom in San Clemente, California. The results of the experiment will be used to construct a 150-acre mitigation kelp reef.

The experimental reef consists of 56 modules. Each module will be 132 by 132 ft, square (40 by 40 m), defined on the sea bottom. The reef design requires the pieces of hard substrate be placed on the ocean floor as uniformly as possible over each module, preferably not stacked, piled, or clumped together. Two construction materials for the reef will be used: quarry rock and recycled concrete. The rocks will be obtained from a quarry and the concrete from demolished structures such as curbs and gutters, bridges, etc.

Coastal Environments compiled measurements of actual substrate pieces (rocks and concrete) which would be available for the project. A relationship was established between length, width, and height of the pieces from the field measurements. The pieces were slab or splinter like rather than cube or sphere like. Based on the geometric properties measured in the actual rocks and concrete examined, the weight of the material required for the experimental reef was estimated.

Four different calculation methods were examined (1) an ideal case (2) a deterministic (3) a probabilistic (4) a worst case scenario. After the four estimates were completed for both material types, the results were examined to quantify the total weight of material required for the project. CE reviewed four construction companies to construct the reef. A construction technique was developed to most accurately achieve the reef design. Project cost was estimated based on material, deployment, engineering, and construction verification costs.

Client:

Southern California Edison

Client Contact:

Southern California Edison
2244 Walnut Grove
Rosemead, CA 91770