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DESIGN CHALLENGES

Surcharge Test Embankment

There are several tried and true methods for managing the settlement that will occur over time on Laurel Island. Like most buildings and critical infrastructure on the Peninsula, deep piling extending to the stable Cooper Marl approximately 85 feet deep will be used extensively on the site. This will ensure that buildings and grade sensitive deep infrastructure won’t settle beyond acceptable tolerances, even during an earthquake.

For roads, parks, and shallow utilities, a different approach will be employed that is based on a unique site specific study that was conducted a number of years ago on Laurel Island. A 15-foot tall large pile of dirt with prefabricated vertical drains (or wick drains) was placed near the center of Laurel Island and monitored for 18 months. The amount and rate of settlement caused by the weight of the dirt was measured and recorded monthly. The conclusion drawn from the 18-month test was that placing surcharge on Laurel Island would accelerate settlement and result in long term settlement amounts that are acceptable within streets, shallow utility corridors and parks.

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