Worked at the Port of San Francisco for many years as a commercial diver/pile driver. Most of the waterfront was a seawall that was concrete (Depression era) but there were areas like Fisherman's Wharf that were wooden. We usually referred to both as seawalls and walls offshore as bulkheads. In 1937 they could have used that term or maybe a East Coast thing? As you know wood in ground contact/never mind in the water will deteriorate so they were likely replacing timbers. We never found any gold coins during work.