AM-TEAM: An Evaluation of Finished Water Reservoir Mixing Conditions

The Issue

The Metropolitan Water District of Southern California (MWD) was investigating options to enhance mixing and minimize short-circuiting within the Finished Water Reservoirs (FWRs) at the Joseph Jensen Water Treatment Plant (Jensen). The objective for this specific project was to provide a better understanding of mixing conditions and identify potential options for modifying the reservoir inlet design at the Jensen plant’s FWR Nos.1 and 2 to minimize chloramine decay and nitrification potential under various flow conditions.

The Solution

AM-TEAM applied Computational Fluid Dynamics (CFD) simulation and biokinetic modeling to assess current mixing conditions in Jensen’s reservoirs and to evaluate potential options for modifying the reservoir inlet design that minimizes short-circuiting within the reservoir.

The Pilot

MWD, with funding support from WaterStart, conducted a CFD study of the Jensen FWRs.  The pilot consisted of modelling the two FWRs at high flow (250 MGD) and low flow (60 MGD).  These flow rates were selected based on historical flow data from 2012 through 2017.  Although the capacity and the flow through each reservoir are similar, their configurations are different.  FWR No. 1 has a baffle wall at the inlet while FWR No. 2 does not.  Additionally, each reservoir has different inlet and outlet configurations and locations. Total project costs amounted to $48,000. WaterStart contributed $25,000.

The Results

Through CFD simulations and analysis, it was determined that the baffle wall at the entrance of the FWR No. 1 provides adequate mixing and allows a plug flow condition through the FWR No. 1 under various flows.  On the contrary, the absence of the baffle wall at the inlet and the location of the outlet of FWR No.2 create a region where water tends to circulate, resulting in higher water age.  Higher water age can contribute to chloramine decay and nitrification.  The regions with high water age within FWR No. 2 were present in both high and low flow conditions.  Through CFD analysis, it was determined that with appropriate modifications, the mixing conditions and the overall detention time in FWR No. 2  can be improved.  CFD allowed the analysis of the mixing conditions under various flows and the evaluation of potential improvement options without making operational changes and requiring actual modifications to the reservoirs.

See animation of tracer concentration!

Further Development

Metropolitan will use the results from the CFD analysis to determine the best option to enhance the mixing condition within FWR No. 2. Furthermore, FWR No. 1 was determined to be effective in its existing configuration; and therefore, no capital funds will be lost due to trial-and-error methodologies being applied.


AM-TEAM provides advanced modelling services based on a unique combination of computational fluid dynamics capabilities and in-depth process knowledge.  The realistic 3D process models allow fast visual troubleshooting, virtual piloting, and virtual testing of solutions offering an alternative to onsite trialing.  AM-TEAM is specialized in multiphase CFD simulation, combined with water treatment process understanding and in-house developed process kinetic models.   Visit to learn more.

Abyss – Drinking Water Reservoir Inspection

The Issue at Urban Utilities

Reservoirs perform an integral function in the storage and delivery of a safe drinking water supply to our customers. The structural condition of the reservoir is perhaps the largest aspect of how it may perform overall in its ability to store drinking water.

The internal inspections of reservoirs can be problematic. Depending on the criticality of the reservoir the asset cannot always be emptied or taken off-line. Current inspections are undertaken by divers, which makes this a costly activity.

The Solution

Deploy an ROUV to capture both above water and underwater footage.

The Pilot

The inspection was conducted over two consecutive days. The scope included:

  • internal inspection of the reservoir through the provision of tethered drone, above and below water,
  • location/identification of interesting features/features of concern,
  • detection of any foreign matter,
  • amount of sedimentation on the floor,
  • condition of internal fixtures and features,
  • detection of ingress points,
  • condition assessment report, and
  • production of a 3D digital model.

Pilot Results

Urban Utilities invested approximately AUD40,000 (USD28,000), of which 50% was funded under arrangements delivered in the Grant Deed between the State of Queensland and the State of Nevada.

The ROUV was deployed from the access hatch on the top of the reservoir. The underwater inspection was undertaken using the submersible ROUV fitted with the Abyss Solutions imaging technology, which comprises a computer vision camera, integrated lighting, and data capturing software. This allows high-fidelity data representation in turbid and low light environments.

The ROUV was also piloted on the surface of the water with an upward-facing camera. Any sunlight-visible was identified and noted as locations of possible ingress.

Abyss Solutions delivered the outcomes of the inspection via a reservoir condition database, web-accessible. The database also enables the download of a printable PDF report. The database houses:

  • reservoir characteristics, including:
    • reservoir details (year built, location, location coordinates)
    • capacity (volumetric, contents, dimensions, water level)
    • construction profile
    • access profile
  • inspection details (date, time, team, weather conditions)
  • scoring guide/legend
  • overall reservoir condition score.

Abyss Solutions also provided a condition assessment and score for individual reservoir elements:

  • access hatch & ladders,
  • floor level outlet,
  • overflow outlet & inlet elbow,
  • inlet pipe, pedestals & straps
  • scour outlet & channel,
  • columns & walls,
  • water stop & concrete lip,
  • telemetry sensors,
  • mixer unit,
  • roof soffit & purlins, and
  • floor

A multi-criteria condition assessment based on the IPWEA Condition Assessment & Asset Performance Guidelines was applied to the reservoir. Each element was been assigned a condition grade ranging from ?0-not rated? to ?5-very poor?. A weighted average was used to assign the overall reservoir condition. High fidelity imagery accompanies the assessment of each reservoir element.

Abyss Solutions also constructed a 3D digital model showing the internal configuration of the reservoir. The model was produced using data from the inspection. The model provides a 3D fly-through of key reservoir components with embedded imagery, and annotations. The method of delivery is via a portal, with a report that can be downloaded, exceeded expectations.

Further Adoption

On the back of this successful trial, Urban Utilities self-funded an inspection of another drinking water reservoir. Adoption of this technology as a business-as-usual solution is under consideration.

About the Technology

Abyss Solutions, located in Sydney, Australia was founded by four scientists and engineers from The University of Sydney in 2014. Abyss is a robotics company that combines the latest innovations in ROUVs with state of the art data analytics to provide a safer, easier and more comprehensive underwater inspection, allowing for correct asset management decisions.