| Warner Avenue Relief Sewer |
This construction project stretched from Los Patos and Bolsa Chica to Warner and Springdale in Huntington Beach, California. The project was built entirely within public streets and was composed primarily of three major operations.
The first operation was approximately 2,000 LF of 3 reinforced concrete encased 18-inch PVC rapped pipe. The pipe encasement was designed to withstand the load of two lanes of traffic since the actual alignment was not more the three feet from the top of pavement. There were several aspects to the operation that made it unique and difficult to complete. First in order to prevent the pipe from floating in the fresh concrete the encasement had to be poured in three stages. In order to start pouring, a bottom layer of reinforcing steel with vertical bars protruding over the pipe had to be placed first and completed before pipe could be installed and the rest of the reinforcing was placed. The pipe could not be placed in the trench first because there would then be no way to maintain the pipe alignment, this was necessary because the sewer utilized a gravity feed system.
The second operation was a 200 LF jack and bore operation that extended underneath the Wintersburg Channel in Huntington Beach. The jacking of the 48-inch steel casing alone was not the difficult aspect of the operation. The ground conditions encountered required continuous dewatering throughout the duration of the process. Three well points were drilled, sump pumps were installed which fed ground water to a desalting tank that then deposited the water into the nearby sewer system. The pumps had to be monitored continuously to ensure that the pumps and the generator powering the pumps were all operating normally. Also, the jacking pit and receiving pits were 30 feet deep in saturated sandy and clay soil with existing utilities running through the area requiring a unique shoring design.
The last major operation was construction of 3,500 LF of a 21-inch VCP sewer pipeline, ranging in depth from 5 to 26 feet. Since this area is in close proximity to the Pacific Coast the ground conditions were rather sandy and saturated, which made the trenching portion of this operation very difficult. More than half of the 3,500 LF the trench had to be maintained with solid sheeting; which meant that beams had to be drilled in ahead of the excavating crew and then plates were lowered down between the beams while the trench was being excavated. This was very slow and a dangerous operation taking into account the bad soil conditions, the location of the trench in proximity to live traffic and the overall extreme depths that the sewer needed to meet.







