The last couple of days I have been hearing the distinctive repeating clank of pile driving both from my office and home. When I initially heard the sound I thought someone might be driving a geoprobe sampler nearby, but the noise was too continuous for geo probe sampling.
On my walk to work I saw the source of the sound. An old rail road bridge crossing Whatcom Creek that has been used as a trail was damaged by a fire, and is now being replaced with steel pile supports being installed over the past few days - hence the loud tapping sound echoing across the north down town area.
The pile driver is a relatively light weight machine that hammers the piles into the ground. The piles must be driven to depth that will support the vertical loads, but also need to be embedded deep enough to support lateral loads on the piles. Soil density and makeup are critical to knowing the depth of the pile. Soils in this area are fill along the creek and glacial marine drift. A deeper dense sand unit is also present. But I am part of this project so don't know the goals for how deep the piles need to be.