A Wet Weather Equalization (EQ) Basin was constructed in the city of Pacifica to mitigate storm-related sanitary sewer overflows. Malcolm installed a diaphragm wall 500 feet from Pacifica State Beach, for the 2.1-million-gallon-capacity basin that is used to temporarily store diluted waste water during large storm events. The ground water level at the site was within 4 feet of the surface. The wall contains 30,000 square feet of concrete, reaches depths of 65 feet, and is 3 feet thick. A cast-in-place wall constructed in front of the diaphragm wall completes the foundation for this beachfront EQ Basin.