After four and a half years, the Miramar Clearwells Improvement Project in San Diego is slated for completion at the end of April. The $94 million project will add 6 million gallons of capacity to the Miramar Facility, providing water to Northern San Diego. The project team has replaced two clearwells built in 1959 and 1973 and constructed a new chlorine contact chamber, lift station, O&M building, security guard shack, and solar power system.
The clearwells, temporary reservoirs for treated water, hold 58.3 million gallons of drinking water combined. Each is the size of approximately three and a half football fields—400 feet by 400 feet. These storage containers allow the treatment plant to keep up with the water demand throughout the day as community water needs ebb and flow.
The team has also constructed a 200-by 200-foot chlorine contact chamber, several chemical injection systems, and an adjoining low pump lift station, which slows the water as it travels through the maze-like concrete baffles of the chamber. This creates the adequate contact time for the water to mix with the chemicals injected upstream of the chamber, which improves water quality. From there, the water flows through either a 72-inch diameter pipe or an 84-inch diameter pipe to the two clearwells.
The low-pump lift station consists of four vertical turbine pumps that push about 40,000 gallons of water per minute each. This station will increase the capacity and water flow as demand is increased throughout the day. When demand is lower, the station can be turned off the chlorine contact chamber can rely upon gravity.
The pipe work in and out of the clearwells has been one of the more challenging aspects of the job. To access the pipes, which were approximately 30 feet deep, the team performed significant excavation, shoring, and relocation of over 30 utilities.
Congratulations to the team on reaching the final stages of this project!