Pomona Perchlorate Treatment Anion Exchange Plant (CA)

Challenge

Pomona is the seventh largest city in Los Angeles County, with a population of over 151,000 residents. 70% of the city’s potable water is produced by city-owned groundwater wells. 25% of the city’s potable water supply is imported through neighboring water agencies including Metropolitan Water District of Southern California and Three Valleys Municipal Water District. The remaining 5% of the city’s potable water supply is local surface water which originates from the adjacent San Gabriel Mountains. The City of Pomona’s groundwater production wells are impacted by contaminants, including nitrate, perchlorate, volatile organic chemicals, arsenic, MTBE, and chromium. Prior to the AEP project, the City had to shut down nine of its groundwater wells after high levels of perchlorate were discovered in the City’s aquifer. In order to meet demand, the City had to increase its purchase of imported water from other water utilities. The City was challenged with having to quickly adapt its existing groundwater treatment facilities to treat increased levels of perchlorate.

Approach

The City hired Arcadis to conduct a study to assess alternatives for increasing output from the existing 23-mgd AEP plant by improving treatment for perchlorate removal. The alternative that provided the best economic value to the City was to add new treatment trains for AEP flows utilizing a specialized perchlorate removal resin. Design-build became an attractive project delivery option for the City because of its speed of delivery, single point of responsibility, ability to incorporate innovative ideas, and lowering the City’s management costs.

With Arcadis serving as owner advisor, the City conducted a two-step procurement process to select their design-builder. A request for qualifications (RFQ) was followed by a request for proposals (RFP) to three short-listed teams. HDR was selected after a proposal review and interview process for the project. The 23-mgd plant improvements included a new anionic exchange treatment process to provide optimal treatment for perchlorate removal. The project also included improvements to prescreening and pumping and conveyance.

HDR’s design and construction services for this project included:
• Obtaining all construction related permits
• Performing all engineering and design services associated with the project (performed by HDR Engineering)
• Constructing the plant, associated pipelines, and appurtenances, complete with electrical and instrumentation systems integrated with City’s     existing SCADA system (performed by HDR Constructors, acquired by QEPC in 2019)
• Compliance with all environmental mitigation requirements (such as the California Environmental Quality Act)
• Finalizing operation plan and provide all associated operation manuals
• Providing operation and maintenance training to City staff
• Completing all required equipment and facilities acceptance tests and resin warranties

Following completion of construction and successful startup, the City of Pomona began operating and maintaining the facilities.

Results

The final design of the plant improvements included a new single-pass perchlorate resin treatment process which can be accomplished directly from groundwater production wells or in series with the existing nitrate resin treatment process. Beginning in August of 2011, the project was designed and built in 13 months at a cost of $7.3 million. Several innovative ideas proposed during the design-build procurement process by HDR were incorporated into the project, including over $200,000 in cost savings for the relocation of the booster pump station, optimization of the AEP layout, deletion of an unnecessary valve vault, and optimized pipeline alignments and pipe sizing. The project now allows the City to utilize its groundwater resources to deliver 23 mgd of reliable high-quality potable water to its customers while reducing the City’s need to purchase more expensive imported water from other water utilities.

This project was the recipient of the American Public Works Association (APWA) Southern California Chapter 2012 Project of the Year – Drainage, Water, and Wastewater.

“The HDR team proposal was by far the most comprehensive in terms of scope and innovative thoughts/optional items for consideration. In addition to providing the technical expertise required to design and construct this project, their proposal provided the best understanding of the critical steps required to construct the project. The HDR team is on schedule and has worked well with our staff and consultants to address issues quickly and equitably to all parties.
“Our engineering staff was able to leverage the success of the Treatment-Perchlorate Facility (AEP) Project to justify amending the city code to expand the use of design-build delivery to other city projects.”
— Tim Hampton, City of Pomona Project Manager and
Senior Water Resources Engineer