Repair and Rehabilitation of Twenty-Year-Old NF Plant Trial and Tribulation

The Deep Aquifer Treatment System (DATS) is an 8-mgd nanofiltration (NF) plant owned and operated by the Irvine Ranch Water District (IRWD) located in Santa Ana, California, that was put online in February 2002 and has successfully operated in the removal of natural organic color causing compounds utilizing organic selective membranes. The facility was constructed using adesign-build approach and put into operation in less than one year. The original membranes are still in use and have never been replaced. However, during the twenty years of operation pressure vessel external supports deteriorated and needed replacement. The original concept was to remove the membranes and pressure vessels, to complete this work. An alternative method was worked out with the contractor to perform the work without removing the pressure vessels. In addition, all the original membrane interconnectors, and end adaptors needed to be replaced. Additional work included repairing and re-coating the interior of three degasifiers, demolition of the existing CIP tank foundation and pad, replacement of the old clean-in-place (CIP) tank with the addition of a mixer, bag filter, and control systems. Concrete repair work, coatings of the CIP area, and product wet well joint sealant removal and replacement was also performed. Focus of presentation will be on the coordination efforts between the contractor, engineering, operations, and inspection groups. Lessons learned will provide benefits to other membrane facility owners so that improvements and methodologies can be planned out prior to actual construction.

This presentation is available to AMTA Members only.