The San Francisco Public Utilities Commission and Water Department needed to replace the existing Lake Merced Pump Station with a more modern facility, while maintaining operations of the existing station. Historical records in addition to a geotechnical investigation indicated the site was susceptible to seismic-induced lateral spreading, liquefaction, and settlement. A ground improvement solution was required to provide a proper foundation for the new structures as well as protection for the inlet pipes off of Lake Merced.
Malcolm Drilling installed over 1,600 individual compaction grouting points at the operating Lake Merced water pump station site. Malcolm batched the grout onsite and utilized twin grout pumps that had a grout pumping piston no greater than 4-inches in diameter through a 2-inch diameter delivery line. Compaction grouting points were drilled with a Klemm 807 and Bauer RG 19. Malcolm also installed a soil mixed/cement secant buttress wall with a Bauer RG 23 and Bauer BG 40, providing a complete ground improvement package.