| Project Description: |
In 1997 the Cucamonga Valley Water District (CVWD) constructed the 3.0 (MGD) Arthur H. Bridge Water Treatment Plant (AHBWTP) to treat water from Cucamonga Canyon, a foothill canyon at the base of Southern California’s San Gabriel Mountains. Canyon water accounts for 10 percent of the district’s supply and helps reduce reliance on imported water for its almost 200,000 customers. In 2010/2011, however, winter storms caused significant damage to the canyon facilities, including the treatment plant intake. This and complications with the original membrane filtration process caused the plant to be used intermittently before it was shut down completely in 2011. CVWD staff recognized the value of this resource and sought to rehabilitate the facility to return it to operation. Over the course of 3 years CVWD staff prepared a plan, commissioned a feasibility study, directed a design-builder, acquired federal funding, and increased the diversity of the district’s water portfolio by returning this plant to operation.
In February of 2011, CVWD staff presented to their Engineering Committee the results of a technical feasibility study for the rehabilitation of the AHBWTP. The study, prepared by AKD Consulting, included a technical review and an engineer’s estimate to construct, operate and maintain two alternative package treatment technologies: Microfiltration membranes or contact clarification-filtration (CC-F). The district staff also determined the best approach to accelerate the completion of the project was by design-build. This would be the first Design-Build project for the CVWD staff. They researched and prepared a presentation to their Engineering Committee (a committee of two Directors of the Board, that review engineering related matters) to describe the benefits of this type of project delivery. After gaining consensus in February 2012 from the Engineering Committee meeting, staff proceeded to procure a Design-Build (DB) entity by a two step process: Request for Qualifications (RFQ) and Request for Proposals (RFP). The purpose of the RFQ was to prequalify (or “short list”) a minimum of three DB entities.
The second step in the procurement process was to invite the three prequalified DB entities to respond to the District’s Request for Proposals (RFP). The RFP defined the scope of work, minimum design requirements, performance criteria, contractual guarantees, and other elements for the upgrades to the treatment plant. The RFP also requested that the proposers develop an innovative design for the repair and upgrade of the intake facilities in the canyon.
The RFP also defined selection criteria by which a selection committee would evaluate the proposals for “best value”. That is, the selection would not be decided by low bid, but rather by various factors including technical approach, team experience, and price.
All three proposers submitted on Contact Clarification-Filtration as the treatment technology selected for their respective base bids. As an alternate treatment technology, two firms proposed a pressure filtration process as manufactured by EPD USA, Inc., which is a California Department of Public Health approved alternative treatment technology. Both proposers gave a credit for this alternative since it was more cost effective than the base bid. Also offered by the proposers as alternatives where other elements not considered by the District but could provide benefit to the project.
Each proposer was also asked to submit a base bid to repair the damaged intakes and an alternative design for the canyon intake that would improve reliability and alleviate maintenance burdens, especially after major storm events. The canyon scope of work, including the base bid and alternative, was a separate bid schedule in order to track costs separately for ease of submitting paperwork to FEMA and Cal OES for the grant reimbursement. The canyon work was evaluated separately since FEMA/Cal EMA funding would cover this cost.
CVWD selected HDR’s proposal with the options of the EPD Pressure filtration process and their alternative subterranean canyon intake structure design. In 2013 CVWD began to rehabilitate the intake facilities and replace the treatment technology, hiring HDR to work with the District and its consultants and permitting agencies on a design-build project that resulted in innovative solutions for both the canyon intake and the AHBWTP treatment process. Challenges to the project included:
• Remote operation of an unmanned and intermittent plant. AHBWTP is typically unmanned and only operational when there is sufficient flow in the canyon.
• The new process needed to be robust and capable of frequent shutdowns while also being low maintenance and with near-complete remote operation.
• The existing space in the building was limited and needed to house a completely different process than it was originally intended for.
• The existing process did not require any pumping and operates solely off existing head from the canyon. It was desirable to maintain a process that did not need pumping.
• The original intake was washed out, damaged and had been replaced multiple times. The previous design created a pond and submerged intake that was easily damaged from debris flows during heavy storms and prone to seasonal algae blooms.
• Proactive management, persistence, and negotiation with regulating permitting agencies, including California Department of Fish and Wildlife, Army Corps of Engineers, and Regional Water Quality Control Board. The project also included a mitigated negative declaration as part of the CEQA determination for the project.
Given CVWD’s limited budget, there were several innovative solutions that reused various components of the existing plant, including raw water conveyance pipeline and strainers, disinfection facilities and underground storage tanks, which were re-purposed for backwash equalization and solids storage, as well as the building, electrical power distribution and other ancillary facilities.
Intake
The new canyon intake features a self-sustaining design that draws both surface water and subterranean flows while allowing storm-driven canyon debris to roll past without impacting the intake’s performance. The new intake also improves raw water quality by eliminating the previously designed shallow intake ponds that were prone to algae blooms during certain times of the year.
The district applied for Disaster 1952 funding and received funding from the U.S. Department of Homeland Security’s Federal Emergency Management Agency (FEMA) and the California Office of Emergency Services (Cal OES). The Design-Build contract was structured so that the intake scope was clearly delineated from the treatment scope, which made it easy at the end of the project to complete paperwork and submit for reimbursement.
Treatment Plant Innovations
Treatment plant upgrades provide a reliable plant capacity of up to 3 MGD. Modifications included replacing the existing membrane equipment with a pressure filtration technology from EPD USA, Inc. The dual-stage EPD pressure filtration system uses a garnet sand media and poly coagulant as a filter aid. The system designed for AHBWTP consists of two treatment trains with a total of 12 filter vessels in the first stage, followed by 10 vessels in the second stage. Each train has a maximum rated capacity of 1.5 MGD, and the design layout allows for a future expansion of up to 3.5 MGD. Water passes through the existing strainers, the first- and second-stage filters, then chlorine is added before the treated water flows to the plant’s clearwell. The poly coagulant is injected upstream of static mixers before the first- and second-stage filters.
The EPD pressure filtration system has been approved by the Division of Drinking Water for 2.0 log Giardia and 1.0 log virus removal credit. The District achieves the remaining pathogen inactivation through free chlorine disinfection.
Design-Build
The design-build project delivery method was chosen for a number of reasons. It provided CVWD a single point of responsibility for design and construction services as well as the opportunity to select innovative and best-value solutions while reducing the overall duration of the project. Although the project was design-build, there were still costs the district could potentially incur as a result of unforeseeable delays and issues related to permitting. Just such an incident occurred. The project was under construction in 2013, during the federal government shutdown, when unforeseeable delays in obtaining Army Corps of Engineering permits were encountered. There were concerns that these delays would make it difficult to complete construction before the rainy season, when it might be too dangerous to work. To solve the problem, HDR, CVWD and its environmental consultant worked in partnership with the permitting agencies to resolve the permitting schedule delay without additional cost to CVWD.
AHBWTP reopened in June 2014. The $4.26 million project was partially funded by a grant from the Federal Emergency Management Agency and the California Emergency Management Agency. |
| Suggested Award Summary: |
The AHBWTP is source-treatment facility of local canyon surface water from the San Gabriel Mountains, specifically the Cucamonga Canyon. Canyon water accounts for 10% of the District’s supply and helps reduce the reliance of imported water for its near 200,000 customers. In 2010, winter storms caused significant damage to the canyon facilities, including the intake ponds, structures, and pipeline. This and complications with the original membrane filtration process caused the plant to be used intermittently before it was shut down completely in 2011. CVWD staff recognized the value of this resource and sought to rehabilitate the facility to return it to operation. Over the course of 3 years CVWD staff commissioned a feasibility study, procured a design-builder, acquired federal grant funding, delivered a successful project, and is once again producing high quality water for the customers of CVWD. The $4.26 million project was partially funded by a grant from the Federal Emergency Management Agency and the California Office of Emergency Services to cover the cost of the canyon intake repairs. The successful project once again improves and sustains the District’s diverse water portfolio for years to come. |
