Design, Construction and Operation of Five Story Tuller Avenue Groundwater Treatment System

WPI was retained to design, construct and provide OM&M services for one of the first remedial systems to remove the fuel oxygenate methyl tertiary butyl ether (MTBE) from a drinking water aquifer. The system uses air stripping to remove dissolved phase MTBE from groundwater. Air stripping off-gas is treated by regenerative thermal oxidation, the discharged to the atmosphere. The complete system includes a two-story control building, motor control center, surge tanks, three 43-foot tall air stripping towers (enclosed in a five-story steel superstructure and façade), a 10,000 scfm Regenerative Thermal Oxidizer (RTO), two 10,000 lb Granulated Activated Carbon (GAC) filtration units; a 180 kW AOP unit; three 4,500-gallon surge tanks; a 6,500-gallon sludge tank; a 3,000-gallon peroxide tank; and a 600 -gallon scale inhibitor tank. 

 

A significant engineering challenge was how to package such an extensive amount of process equipment into such a small footprint, and meet the necessary maintenance access requirements. Only two small, narrow land parcels located on a utility company property were available for construction of the system. 

 

The first parcel, used for the two-story control building, air strippers, AOP system, and RTO, directly abuts a major freeway. The second parcel, used for the surge tanks and GAC vessels, is located approximately 100 feet from the first parcel. Another engineering challenge was the underground infrastructure consisting of dozens of groundwater conveyance lines traversing existing utilities under some of the busiest roadways in West Los Angeles, including a State Highway (Venice Blvd).  All civil and mechanical design work was done in-house by WPI

 

The soil and groundwater treatment system is operated by a programmable logic controller (PLC)-based system that interfaces with all aspects of the system including submersible groundwater pumps, surge tank level controller, air stripping towers, the RTO, the AOP system, GAC system, variable speed drive pumps, the SVE vacuum blower, and multiple leak detection sensors. A PC-based human/machine interface (HMI) allows for automatic system startup/shutdown, real-time access to all measured parameters, and data acquisition/archiving.
Although there are no statistics marinated for such systems, WPI believes this to be one of the largest MTBE remediation systems constructed in the United States. 

 

Construction on this 400 gpm system was completed in 1999, and it has now been in continuous operation for more than 12 years.  It has treated over 1.2 billion gallons of groundwater.  The system has achieved a 90% uptime performance – virtually unheard of for a system of this size and complexity. 

 

During this entire period, all system OM&M has been provided by WPI since system startup.  OM&M responsibilities include data collection, system assessment and optimization, regular maintenance and repairs to equipment, implementing reconfiguration or revisions to existing system designs, installing a variety of controls and instruments for system enhancement, and the collection of influent and effluent vapor and water samples to demonstrate permit compliance and evaluate system performance.