Orange County Branch Newsletter

December 2015

OC EWRI

Update on the Irvine Ranch Water District Membrane Bioreactor Project


By: Ankita Vyas, EIT

Steve Malloy, Principal Engineer with Irvine Ranch Water District (IRWD) for over 25 years, presented to the EWRI Orange County on the Michelson Water Recycling Plant (MWRP) Phase 2 Expansion. The primary goal for this expansion was to increase the recycling capacity of the existing MWRP by 10 million gallons per day (MGD). There were several alternatives considered for the expansion, including the expansion of existing biological treatment and filters or adding in a parallel membrane bioreactor (MBR) train. After careful consideration, IRWD decided to add a parallel MBR train to the existing plant due to its ability to comply with future regulatory guidelines, smaller footprint, its ability to remove total dissolved solids (TDS), and an increase in water quality.

The Phase 2 Expansion included new influent sewers, new headworks, expansion of sedimentation tanks, expansion of flow equalization facilities, a new high rate clarifier, a new MBR, new ultraviolet disinfection facility, upgrades to the chlorine contact basin, new chemical facilities, and new electrical facilities. Construction of the expansion started in 2009, and the plant was in full commission by early 2014.

IRWD faced several challenges throughout the expansion project, from managing multiple new equipment vendors and change orders to overall coordination with contractors. Mr. Malloy stressed the importance of good communication with the vendors and contractors prior to construction to reduce potential increase in overall cost due to change orders. Mr. Malloy also mentioned that upon installation of the GE Power & Water vendor’s parallel process train within the MBR facility, a few issues were encountered with the programming of the trains. This led to additional cost, as the manufacturers had to reprogram the MBR, trains accordingly. Therefore, due to such change orders over the phase of this project, the final construction cost for this MWRP Phase 2 Project expansion cost was $133.7 million instead of the original estimated $88.5 million.

Overall, the MWRP Phase 2 expansion project was successful with several lessons learned. This project is an inspiration for the use of new and innovative methods of water treatment. Its performance will be an example for other future expansion projects.