Project Details

  • Location:
    Carlsbad, CA
  • Delivery Method:
  • Design Engineer:
    Black & Veatch
  • Constructed Value:
    $41.3 million
  • Completed:
    September 2009
  • Project Highlights:
    • Cutting-edge biosolids
      recycling facility
    • Andritz sludge drying and
      pelletizing plant
    • Alfa Laval Centrifuge
    • 3.0 megawatt cogeneration
    • Digester gas system produces
      methane gas used to produce
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Encina Water Pollution Control Facility Phase V Expansion

Encina Wastewater Authority

Filanc completed the installation of these facilities in a most professional manner and without installation discrepancy. They are helpful in providing solutions...They are a valuable resource to EWA and I highly recommend them for similar projects.
Kevin M. Hardy, General Manager
Encina Wastewater Authority
The Encina Phase V Expansion project was a major plant retrofit and expansion to update the plant’s biosolids handling and energy management facilities.

Biosolids Handling

The existing plant utilized four belt presses for dewatering of the digested sludge. Filanc relocated all underground wet utilities in the primary and Dissolved Air Flotation (DAF) area of the plant, installed several hundred cast in drilled hole piles, and built a new biosolids dewatering and drying facility. The new facility consists of two Alfa Laval centrifuges and an Andritz sludge drying and pelletizing plant complete with product storage silos, support chemical systems, and air pollution control equipment. A new digested sludge feed pump station, sludge holding and mixing tank, and polymer and ferric chloride chemical facilities were also constructed in the biosolids handling upgrade. After successful commissioning of the centrifuges and sludge dryer, the existing belt presses and support equipment were demolished to make room for a future project.

Energy Management

The energy management upgrade included the installation of a 3.0 megawatt cogeneration facility with four internal combustion generators burning digester gas, digester gas system upgrade and expansion, paralleling gear with load shed/add control systems, replacement and upgrade of aeration blowers and blower controls, installation of an above-ground hot water supply and return loop (replacing a below ground loop), cogeneration heat recovery and shedding systems with multiple pumps and heat exchangers, upgrades to plant utility water systems, upgrades to plant process and instrument air systems and complete replacement of main plant distribution gear and electrical feeders to all process area Motor Control Centers (MCCs). The energy management upgrade required 128 complete or partial plant electrical shutdowns and multiple digester heating system outages.


The Encina Phase V expansion required compliance with Air Quality Management District permitting for the sludge dryer, regenerative thermal oxidizer burners, and system stack emissions. California Air Resource Control Board permit compliance was required for the internal combustion cogeneration engines. Compliance was required with San Diego Gas and Electric’s onsite power generation permit. Various agency permits were required for National Fire Protection Association (NFPA) compliance on the digester gas compression and utilization equipment, as well as explosion prevention equipment and nitrogen purge systems.


This project received well-deserved attention that stemmed from the innovative green technologies employed at the plant. The facility’s Phase V Expansion featured cutting-edge biosolids recycling technology that transformed sludge into dry pellets and reduced the plant’s solid waste volume by nearly 80 percent. Thanks to a heat-drying process, the waste achieved an Environmental Protection Agency Class A Biosolids rating, thus allowing Encina to package and sell the pellets as fertilizer for local agriculture businesses and golf courses.

Startup and Commissioning

Construction of the biosolids handling and energy management facilities required more than 200 outages, tie-ins, and shut downs. All work was carefully coordinated with plant staff at every level. During the course of construction and commissioning, there was not a single spill or single day that activities resulted in out of compliance plant effluent.


Installation of the sludge dryer and pelletizing plant allowed the owner to eliminate the need for offsite trucking and disposal of dewatered sludge, which previously required hauling dewatered sludge in excess of 200 miles for disposal.

All biosolids and energy management facility upgrades were fully integrated into the existing plant Supervisory Control and Data Acquisition (SCADA) system, allowing remote operation from the facility’s centralized control room and/or unattended operation.

Plant operations and maintenance staff received training from equipment suppliers, SCADA integrators, and the design team. All training was proctored by a third party commissioning engineer hired by Filanc.


Filanc managed the safety program to achieve 98,458 self performed man-hours with no lost time incidences.