We are working on an existing warehouse building in San Francisco area. The building was built in 1930s and founded on timber piles. So far reviewing of as-built information does not provide us with pile length/pile tip elevation. Pile quality is another issue. A majority portion of each pile is under water, and about 3 feet of the pile length is within the water fluctuation zone. The portion within the fluctuation zone raises our concern on the quality of piles. To provide the geotechnical capacities of the piles, we have to find the pile tip elevation and if the piles are structurally sound. Anyone has worked on the similar project? Any good idea or technology to do so? We are considering exposing certain piles to observe the pile conditions, but maybe limited by access and the extent that we can go. Responses are appreciated.