PROJECT

Water Treatment Plant Expansion & Renovation

Our team provided study, design, bid and construction-phase services for expanding the City of Monroe’s Water Treatment Plant (WTP) from a rated capacity of 12 million gallons per day (MGD) to 24 MGD.

The plant had two conventional treatment trains. Growth in the region over the past decade had increased daily water demand beyond the plant’s rated capacity. Water quality was also challenging due to the integration of multiple water sources, high manganese content, taste and odor issues, and disinfection byproduct formation.

Initial Study & Renovation

In the initial study, we recommended process improvements to increase the rated capacity of the existing facilities, but water demand did not allow for removal of either train for an extended period to allow the work to be completed. An expansion to add 8 MGD of capacity was recommended as the first step to then allow subsequent rehabilitation of the existing trains. We performed the preliminary design and estimated construction costs for this expansion.

Our design focused on maximizing capacity of this portion of the plant while integrating expansion concepts with the existing WTP. Modifications could be made to the existing facilities to improve the treatment process and hydraulics, allowing the existing trains to be rerated for 16 MGD. This introduced challenges, including a very constrained site, hydraulic bottlenecks and critical sequencing.

Client

City of Monroe

Location

Monroe, Louisiana

Region

Southeast

Services

Construction

Municipal Water & Wastewater

Advanced Water & Wastewater Treatment

Industry

Water

Improvements to the plant included chemical modifications and installation of new primary treatment equipment to provide better removal of total organic carbon and manganese, as well as facilitate treatment of a secondary water source. Powdered activated carbon was added to the treatment process to remove tastes, odors and organics. Chlorine and ammonia systems were modified to improve primary disinfection and provide increased flexibility for operational modes.

Project elements included raw water conveyance, rapid mix, flocculation and sedimentation, filtration, disinfection, more than 5 miles of chemical feed piping, and finished water pumping. We coordinated closely with the city, conducting interactive workshops to compare alternative approaches, discuss equipment options, review cost opinions, communicate with regulatory officials, and engage and inform key stakeholders throughout the preliminary design process. Cost opinions were developed, and a rate study was conducted to assist the city with raising the required capital funds for the project.

New Treatment Train & Expansion

In addition to renovation of existing facilities, an 8 MGD expansion was added to the WTP, to reach a rated capacity of 24 MGD. The new treatment train includes aeration, static channel mixers, walking beam flocculators, vacuum sludge removal, plate settlers, collection launders with v-notch weirs, and media filters with air scour.

The project also includes a new chemical storage and pumping facility; a complete electrical power and controls upgrade; new pumps with variable frequency drives (VFDs); architectural and HVAC improvements; and equipment upgrades in the existing treatment trains.

Critical electrical improvements at the existing treatment facility include a new primary power feed, switchgear, an electric room, a diesel engine generator, rewiring of all existing electric operated components, and SCADA system and security improvements. New HVAC systems were installed in the chemical rooms, laboratory and administration areas. As the city’s sole producer of potable water, the WTP needed to remain operational during construction, so minimization of outages was a key aspect of the design.

The team designed a new chemical storage facility, which includes outdoor and indoor storage. Key changes from the previous chemical setup:

• Increased capacity to match plant capacity

• Improved safety features, such as chemical containment and chlorine scrubber

• Increased number of pumps and feeders for additional redundancy and flexibility

Soil conditions require the treatment train, finished water clearwell and administration facility be supported on a pile foundation. The architectural design of the treatment facility expansion retains the timeless look of the 1967 treatment facility while improving functionality for staff. Updates to the existing facility include a renovated control room and laboratory and all-new administrative facilities — modern office spaces, conference rooms, training areas and common spaces.

Scope of Work

Rate study

Study, design, bid and construction-phase services

Municipal drinking water treatment

Process design

Treatment process optimization and design

Plant renovation

Raw water pumping and conveyance

Electrical power and controls

SCADA upgrades

Administration building

Concrete basins and clearwell

Auger-cast piles

Chemical storage and feed systems

Finished water pumping