Griffin Fluid Management

Gerald Desmond Bridge Replacement Project

Long Beach, California

OWNER

Port of Long Beach

TIME

2019

GRIFFIN DIFFERENCE

Unusually heavy and persistent rains, unanticipated changes in soil conditions, design changes and previously unknown underground obstructions required the Griffin team to continuously monitor and make system adjustments to adapt to the changing conditions to keep the job moving forward.

THE CHALLENGE

The 400 ft. 48-inch storm drain system under the bridge needed to be modified for the new construction. The deepest section of the excavation went to an elevation of 20 ft below sea level. The challenge was to create sufficient drawdown without lowering the water table below the limits of nearby monitoring wells, while considering that the total discharge flow was limited by the client’s treatment facilities.

THE SOLUTION

Griffin designed and installed 25 deep dewatering wells to 35 ft. on 18-20 ft. centers. The close spacing of the wells concentrated the area of drawdown to a short excavation area. This design allowed excavation to proceed by operating only as many wells as needed to dewater small sections of the excavation. The wells averaged around 15 GPM however, individual well capacities varied considerably due to varying soils.