Water and Wastewater Treatment

Brentwood Wastewater Treatment Plant Expansion Project


The City of Brentwood required an expansion of its ten mgd wastewater treatment plant, which was originally designed by TJCAA in 2000. The design included deep dynamic compaction and stone columns because of the site’s vulnerability to soil liquefaction.


TJCAA provided an expansion design that included a blower building, maintenance shop, secondary clarifier, return activated sludge pump station, waste activated sludge storage basin, 5,000-square-foot biosolids drying facility, 15,000-square-foot biosolids storage facility and new aeration basins. Because the plant site had soils that are subject to liquefaction, the design featured soil improvement measures for areas that were not previously mitigated during construction of the existing plant.

Client: City of Brentwood

Location: Brentwood, California USA

End-Market: Water/Wastewater

Facility/Project Size: 10-mgd

Key Features: Multiple structures; Expansion of existing facility; Soil mitigation measures

Solids Handling Facility


The Santa Clara Valley Water District required structural, electrical and I&C discipline designs for improvements to its residuals management project to extend the life of its Rinconada Water Treatment Plant. Planned improvements included sludge storage and processing capacity to ensure reliability and redundancy, minimizing the risk of discharge violations.


TJCAA provided all electrical and I&C discipline designs for the Residuals Management Project. TJCAA prepared final design documents for project elements including a new 1,500-kVA unit substation, motor control centers, fiber optic cable allocations for the control network and communication systems, newly distributed PLC and lighting. Electrical design included a provision for future double-ended substation, smart motor starter, variable frequency drives and integration of supplier-furnished packaged conveyor and centrifuge systems. TJCAA provided the structural design for the new gravity thickeners, a two-story concrete building housing new centrifuges and electrical equipment, and a steel-frame load-out structure. TJCAA also provided engineering services during construction for the project.

Client: Santa Clara Valley Water District

Location: Los Gatos, California USA

End-Market: Water/Wastewater

Facility/Project Size: 100-mgd

Key Features: Centrifuge thickening; Drive through truck bay; Gravity thickeners; Sludge conveyance

Wastewater Treatment Plant Expansion

Ironhouse Sanitary District

Oakley, California

TJCAA performed the structural engineering design for the 9-mgd expansion of a wastewater treatment plant for Ironhouse Sanitary District, which handles the wastewater from Oakley and Bethel Island in eastern Contra Costa County, California. TJCAA’s 118-sheet design included the influent pump station, headworks, anoxic/aeration basins, membrane bioreactors, backpulse tank, blower/electrical/generator/chemical CMU block building, UV/Effluent pump station, and the solids handling building.

The design also featured pre-engineered metal canopies over the membrane bioreactors and UV structures with 2- to 5-ton bridge cranes. The Ironhouse plant’s location adjacent to a wetland presented a design challenge in that the existing soils required ground improvement via impact-rammed aggregate piers in order to support structures and mitigate soil liquefaction potential. TJCAA also provided services during construction, which was completed in October 2011.

Key Features:

  • Two Pump Stations
  • Multiple Buildings, Basins, and Tanks
  • Ground Improvements
Recycled Water Treatment Plant

Delta Diablo Sanitation District

Pittsburg, California

This project was a structural design for expansion of a recycled water facility to 14 mgd. This expansion was implemented to provide additional treatment to WWTP effluent, for reuse by Calpine in its cooling towers at two power generation facilities. As part of the RMC Water and Environment team, TJCAA provided structural design, including a predesign phase, evaluation of reservoir materials, structural design services for the development of the bid package, and engineering services during construction. The TJCAA design included the following structures:

  • Influent Pump Station
  • Chemical Storage Facility
  • Electrical Building
  • Semi-Packaged Clarifier Settling Basin
  • Semi-Packaged Filter Basin
  • Chlorine Contact Basins

Also incorporated within the project were a 2-MG, above-grade, welded steel reservoir and associated pump station. The design was conducted according to an aggressive, demanding schedule, and TJCAA delivered its design on schedule and under budget.

Reliability Improvement Project


The Santa Clara Valley Water District sought to increase capacity and improve reliability at its Rinconada water treatment plant. As the main water treatment plant serving the western service area, the Santa Clara Valley Water District needed to keep it in operation throughout its $180 million plant modernization project.


TJCAA developed structural and electrical designs that accommodated continued operation of the plant throughout the estimated five year construction period. Structural designs included a new ozone generation building, LOX facility, washwater recovery facility, chlorine contact basin, flocculation-sedimentation basins, filter and an elevated concrete platform to support electrical equipment.

TJCAA’s electrical design included new 12-kV distribution, Arc Flash protection strategies, a new 3-MW diesel standby generator and newly distributed motor control centers with smart motor starters and variable frequency drive equipment. The I&C design incorporated newly distributed PLC architecture, coordinated with construction phasing and new developed processes.

Client: Santa Clara Valley Water District

Location: Los Gatos, California USA

End-Market: Water/Wastewater

Facility/Project Size: 100-mgd

Key Features: Multidiscipline design; Designed to maintain operations throughout construction; Multiple structures and systems.

Civic Center Way Treatment Facility



The City of Malibu’s civic center way treatment facility, collection and recycled water recharge project collects wastewater for the greater Malibu area and treats it at a membrane bioreactor treatment plant. By incorporating tertiary treatment and UV disinfection, the resulting recycled water was for use with landscaping, irrigation and injection into the Malibu Valley Groundwater Basin to mitigate seawater intrusion. Due to the sensitive coastal area and the high-profile community, special care was needed to reduce aesthetic and noise impacts.


TJCAA provided electrical and I&C designs for six new Southern California Edison electrical services, distributed motor control centers, and standby generators at the wastewater treatment plant and two critical lift stations. The control system consisted of ten Rockwell CompacLogix PLC systems connected via a fiber optic Ethernet ring and a pair of ignition SCADA servers that allow full monitoring of the system. Remote sites are monitored and controlled from the facility using a single-mode fiber optic radial system, installed with collection and recharge system pipelines. TJCAA’s motor and generator set selection addressed the acoustic consideration of the site.

Client: City of Malibu

Location: Malibu, California USA

End-Market: Water/Wastewater

Facility/Project Size: 60-mgd

Key Features: Electrical distribution and standby power; SCADA, I&C and CSP

Groundwater Replenishment System

Orange County Water District and Orange County Sanitation District

Fountain Valley, California

This $487-million, 10-year project, which was funded jointly by the Orange County Water District and the Orange County Sanitation District, included an Advanced Water Treatment Facility and Ground Water Replenishment System. The facilities were designed to reuse approximately 140,000 acre-feet per year of advanced treated wastewater. The design consisted of a membrane treatment system that takes highly treated wastewater and purifies it beyond drinking water standards using microfiltration, reverse osmosis, and ultraviolet disinfection. The low-salinity water percolates through the ground and recharges Orange County’s aquifers. This water will also help maintain an underground freshwater barrier between ocean water and freshwater.

TJCAA was one of six structural engineering firms involved in the design phase of the project. TJCAA’s role was to provide pile foundation consulting services for the entire project, which included 34 structures, requiring 3,640 piles. During the design phase, prestressed concrete piles were selected as the foundation system. Upon contract award, the system was revised to a DeWaal Pile System, requiring TJCAA to respond with design services under a very aggressive schedule.

TJCAA provided structural design, predesign, and services during construction for pile foundations. The structural design of the project was shared among six structural engineering firms; however, the foundation design for all 34 buildings was performed by TJCAA. This required extensive coordination and communication with all of the structural firms, which were in diverse locations. A unique feature of this project is that the majority of the interaction amount the firms was achieved via electronic media.

Key Features:

  • Pile Foundation Design
  • Coordination Among Firms
Wastewater Treatment Plant Expansion

City of Brentwood, WWTP Expansion Project

Brentwood, California

The Brentwood WWTP Expansion Project, with a construction value of over $48 million, included replacement of an existing plant while the existing plant remained operational until completion of the new facilities. TJCAA provided structural design, predesign, design, and construction services for the entire upgrade facility as part of the G.S. Dodson & Associates, Inc. team. The TJCAA design include the following structures:

  • Solids Handling Headworks and Electrical Building
  • Influent Pump Station
  • Denitrification Basin
  • Oxidation Ditches
  • Chlorine Contact Basins
  • Tertiary Filters
  • Chemical Handling Facility
  • Administration Building
  • Outfall Structure
  • Cascade Aerator

These structures were designed for construction with cast-in-place concrete, structural steel, and concrete masonry. Due to its visibility from a bicycle path along the river, the cascade aerator design required special attention to aesthetics. The design featured simulated rock, to achieve a waterfall effect, serving both functional and aesthetic purposes. The site has liquefiable soils, and TJCAA designed several schemes for upgrading the soils; ultimately, the City of Brentwood elected to use the stone column scheme.

This project, which required coordination with multiple offices, had a demanding schedule. TJCAA delivered its design on schedule and within budget.

Key Features:

  • Multiple Structures
  • Highly Visible Site
  • Ground Improvements

Reservoirs And Pump Stations

Gauntlett and Iversen Reservoirs, City of Healdsburg, CATJCAA provided analyses, recommendations, and construction cost-benefit analysis for replacing the roof of the Gauntlett and Iversen Reservoirs, two lined, earthen reservoirs. As part of this project, TJCAA inspected the reservoirs, assessed condition, and performed preliminary structural analysis. TJCAA identified replacement roof system options for the Gauntlett Reservoir with consideration given to three scenarios including the potential for installation of rooftop solar arrays.

The project addressed operational issues at a lift station including design improvements for motors and drives, updating control systems, and electrical servicing. TJCAA’s design team developed sequence of construction, phased service replacement, drive replacement, and infrastructure improvements to ensure continuous pump availability during construction. Additionally, the project included upgrades to the facility’s SCADA system RTU controls, including new hot standby redundant PLCs and backup PLC controls to eliminate pump station vulnerability to single points of failure.

TJCAA provided structural design and construction services for the 1-MG, welded steel recycled water tank and supporting pump stations. This project, which provided service for a golf course recycled water system, required coordination with two agencies: those of both the water purveyor (Delta Diablo Sanitation District) and the end user. To meet cost objectives, TJCAA’s clients elected to use pre-cast units for all of the support structures, vaults, and manholes. TJCAA provided a low-profile tank design that accommodated the needs of the constrained site, which was within the City of Pittsburg’s Delta View Golf Course. The main pump station building was a prefabricated masonry unit, and the building for the booster pump station was of prefabricated, fiber-reinforced plastic.

Key Features:

  • Low-Profile Tank Design
  • Pump Stations
  • Highly Constrained

This project included structural design and construction management services for a 2,176-square-foot wastewater pump station/electrical building. The design for this large concrete masonry unit used a double hip roof and other architectural features that allowed the structure to blend with its setting in the Ruby Hill area of Pleasanton, California. The design for this pump station was further constrained by the need to maintain clearances on the site, which was next to a fire station. This project required coordination with multiple entities, including the lead firm Garber Engineering and the City of Pleasanton. TJCAA also provided services during construction.

Key Features:

  • Constrained Site
  • Architectural/Aesthetic Requirements
  • Coordination with Multiple Entities

Buildings and Structures

Novato Sanitary District, Seismic Evaluations

TJCAA performed structural evaluations of digesters (concrete structures) at the District’s WWTP and deep bed filters and secondary clarifiers for the District’s tertiary treatment facility. TJCAA’s evaluations identified seismic vulnerability, verified code compliance, and determined locations for new equipment in existing structures. TJCAA evaluated options for placement of filtration, disinfection with UV or chlorine, and residual disinfection systems at the recycled water facility. Emphasis was put on finding options for reuse of existing structures.

Brentwood, WWTP Expansion Project

The Brentwood WWTP Expansion Project, with a construction value of over $48 million, included replacement of an existing plant while the existing plant remained operational until completion of the new facilities. TJCAA provided structural design, predesign, design, and construction services for the entire upgrade facility as part of the G.S. Dodson & Associates, Inc. team.

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City of Belmont-Recreation Facility

Structural design of a two story concrete block recreation facility and two concession/restroom buildings for new softball fields.

City of Glendale- Groundwater Remediation Project

Structural design of facilities associated with this ground water remediation project. Elements included seismic anchorage, operations facilities, chemical storage, groundwater well vaults and a 240 foot clear span pipe crossing over an existing water channel in Glendale, CA. The project required mat foundations to accommodate potential settlement from the existing unconsolidated soils.


Alameda County Water District, Communications Project

This communications project included planning and design for a high-speed communications backbone for ACWD’s SCADA and LAN communications networks. The project goal was to establish redundant high-speed network links connecting all critical production facilities. To mitigate potential public concerns, TJCAA facilitated a series of needs assessments to establish functional requirements and identified an approach based on a 20-foot mast at one facility with a repeater located on a nearby ridge.

East Bay Municipal Utility District, Electrical System Modeling

TJCAA performed electrical system modeling using SKM PowerTools© for two existing water treatment plants in the San Francisco Bay Area. Work included inventorying existing electrical equipment; revisiting previous short circuits, coordination studies, and Arc Flash calculation; and data logging of harmonic distortion levels. The modeling provided for: updating the existing facility’s Arc Flash study to meet NFPA 70E; identifying methods for reducing Arc Flash hazards; and developing harmonic distortion models to mitigate power quality concerns related to the new ozone equipment.

Monterey One Water, Arc Flash Study

TJCAA analyzed 51 sites, calculated the risk of an Arc Flash at each facility and developed recommendations for risk improvements. TJCAA modeled each site using SKM PowerTools©, existing equipment ratings, protection, device coordination, and Arc Flash levels. TJCAA made recommendations for equipment upgrades and protective device settings to improve coordination and/or reduce Arc Flash energy and established documentation. The project also included preparation and application of Arc Flash labels and safety training for compliance with NFPA 70E.

Santa Cruz, Graham Hill Water Treatment Plant Electrical Improvements

Provided electrical and structural design for the renovation, expansion, and improvements to the electrical distribution system at the City’s main Graham Hill WTP.

Facility Electrical and Industrial Applications

Cucamonga Valley Water District, Booster Station 1C and 2C Project: Design and construction services for two large booster pump stations. TJCAA provided a very fast track design, assistance with prepurchase of the electrical distribution and motor starter equipment, development of a District wide tagging scheme, and P&ID standards.

Standby and Emergency Power Facilities

Contra Costa Water District, Treated Water Generators and Seismic Valves Project: Incorporated standby power (diesel engine generators) and emergency seismic shutoff valves to several of the District’s treated water pump stations and reservoirs. Installations were in residential areas requiring weatherproof and critical sound-attenuated enclosures for the generators.

Electrical System Modeling, Analysis, and Utility Coordination

East Bay Municipal Utilities District, Walnut Creek Water Treatment Plant Upgrades: Electrical design services for major plant upgrade. Electrical upgrades include 12 kV and 480 Volt distribution, motor control, building support systems, and standby generator. Studies included generator sizing evaluations, load flows, short circuit, and reliability analysis.

Facility Electrical and Industrial Applications

United Water of Idaho, Columbia Water Treatment Plant: Design/Build electrical and instrumentation and control design of ultra-filtration membrane treatment process. Electrical design included new utility service, 480 Volt distribution and motor controls, and facility lighting and electrical.

Medium and Low Voltage Distribution-

Contra Costa Water District, 5kV Electrical System Upgrade Phase 1: Design of replacement for 35 year old electrical distribution equipment. Project included new electrical service building, 5kV distribution equipment, 5kV motor starters for large (1500 and 700 hp) high lift pumps, and other improvements.

Instrumentation and Control

Instrumentation and Control Project for Alameda County Water District in FremontThe PLC upgrade project for a 21-mgd water treatment plant modernized an obsolete PLC system. TJCAA performed field investigations to update the as-built wiring diagrams, system design narratives, and coordination spreadsheet and programmed the new system to use the client’s existing control logic. In coordination with ACWD staff, TJCAA performed I/O testing, SCADA testing, and functional testing that simulated process inputs before the equipment was installed. TJCAA’s work on this project also included equipment commissioning, including operational readiness testing and functional acceptance testing.

The project addressed operational issues at a lift station including design improvements for motors and drives, updating control systems, and electrical servicing. TJCAA’s design team developed sequence of construction, phased service replacement, drive replacement, and infrastructure improvements to ensure continuous pump availability during construction. Additionally, the project included upgrades to the facility’s SCADA system RTU controls, including new hot standby redundant PLCs and backup PLC controls to eliminate pump station vulnerability to single points of failure.

United Water of Idaho, Columbia Water Treatment Plant: Design/Build of ultra-filtration membrane treatment process. Project required development of electrical and I&C documents at a level sufficient for construction permitting and to develop a guaranteed maximum price (Design/CM at Risk).

City of Santa Cruz, Graham Hill Water Treatment Plant Control System Upgrade: System upgrade project including vendor selection, system design, panel fabrication, coordination of subcontractors, installation, startup, testing, training, and follow-up/warranty tasks.  The resulting SCADA system includes hot standby, redundant PLCs, updated plant control strategies, human/ machine interface software, RAID Category central workstations, and 30 remote radio telemetry units.

City of Folsom, Water Treatment Plant Control System Upgrade Design/Build: The control system architecture was designed to accommodate a doubling of plant capacity without modifications to the control system approach.  The suitability of the approach was confirmed during subsequent plant expansion. Design/build approach included design of control system architecture and interface to remote telemetry, fabrication/installation of PLC back panels, testing and startup.

Seattle Public Utilities, Tolt Water Treatment Plant: Design/build grassroots 120 MGD treatment plant that included ozonation, flocculation, filtration, chemical feed, solids handling, and on site clear well storage.  For the instrumentation and control system, a distributed control approach was used