Update from the design team:

The EWB Usalama group has been hard at work over the past few months, working on the Alternatives Analysis, Preliminary Design, and Pre-Implementation reports in anticipation of our implementation trip in September (!).

Our technical team, led by Marc Santos, has been very busy putting together the pieces for a working water distribution system while considering cost, ease of construction, and other factors that will affect the on-the-ground portion of our project. Information about some of our main design considerations follows below.

–        One essential part of the design is the new water tank that will be constructed for the community, at a location that will provide enough gravity head to allow water to be drawn from all five of Usalama’s distribution kiosks. Charly Bertran, Avi Guter, and Matt Sisul, each with experience in structural and/or mechanical engineering, headed up the design process for the tank. The structure will be composed of reinforced concrete and quarried stone, utilizing local materials and construction techniques.

–        The team used a software program called EPANet 2.0 to model the hydraulics of Usalama’s water system. Patrick Farnham and Marc Santos used location data, including elevations, to construct a model of the existing system that was true to existing conditions down to pipe size and composition (PVC, galvanized iron, etc.). By running flow simulations, we were able to identify areas of low and negative pressure within the system and troubleshoot these issues by varying pipe parameters. Our final design is based on a hydraulically-functioning EPANet flow model that includes the new tank, several new sections of piping, and a possible new location for Kiosk 5, which could potentially serve more residents and require less travel time.

–        Nick Rose headed up the water treatment portion of the design. Utilizing water usage data, required chlorine contact times and dosages, and feedback from the community about various disinfection techniques, the team settled on a point-of-distribution method. Kiosk operators will be taught how to dose each customer’s jerrican with a dilute bleach solution, neutralizing disease-causing viruses and bacteria that could potentially be present in the dispensed water.

–        The team needed to consider the design of the pump that will keep Usalama’s new water tank full until to the activation of a new nearby government line. This effort was taken on by Mike Jangl, who weighed factors like total static head and distance between the new and existing water tanks, the desired fill time for a pump cycle, and friction-caused head losses associated with its operation.

–        The issue of pipeline protection against elephants is another important one, and one that is certainly unconventional for American engineers. Dareen Salama assessed several possible design alternatives, passing on beehives, chili powder, and bamboo spikes in favor of a soil/rock pipe cover combination. This should encourage thirsty elephants to seek out surface water rather than competing with Usalama’s residents and damaging their infrastructure in the process.

–        Construction scheduling, design, and safety are as important to an EWB project as to any other work site. Jack Naidoo and Nolan Mazur created our anticipated work schedule, attempting to efficiently complete multiple simultaneous tasks while also providing adequate team supervision and avoiding accidents and injuries.

–        Claire Wang and Sooin Kwak were in charge of the team’s Operation and Maintenance plan, which will see Usalama learning everything there is to know about managing their new functional water system while keeping it running for many years to come. Appointed members of the community will conduct routine inspections of all system components, while the water board makes sure that management of the pipeline stays profitable.

The technical team just presented a synopsis of the Pre-Implementation report to EWB-USA’s technical advisory committee (TAC), and received its approval of our design. We are now planning travel details, and the team is well on the way to a successful implementation in less than 2 months!

–        Patrick Farnham

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