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Dam, Canal, Forebay, Penstock, Powerhouse, Tailrace

Dam, Canal, Forebay, Penstock, Powerhouse, Tailrace

January 21, 2016

Authored by Nason McCullough, a geotechnical engineer in the original CH2M Corvallis, Oregon office who is also serving in geotechnical volunteer role on the Engineers Without Borders Guatemala team.

The Forebay, Penstock, and Powerhouse with Jan Spies and Andy Carr.

The Forebay, Penstock, and Powerhouse with Jan Spies and Andy Carr.

Inspecting the Diversion Canal with Andy Carr.

Inspecting the Diversion Canal with Andy Carr.

Joyabaj Diversion Dam.

Joyabaj Diversion Dam.

I had the honor to be a part of a team from CH2M helping two communities in Guatemala – Nueva Providencia and Joyabaj. The visits to these communities reminds me how lucky I am; it is an unfortunate fact of our world that many are born in a place, in a situation, and at a time such that they do not have the basic infrastructure that affords so many of us a comfortable life and opportunities. How lucky I am that when I turn on my tap the water that flows out is not contaminated, I have reliable electricity that can power more than a couple light bulbs, and bridges and roads that connect my house to my work. Though I had not worked with Engineers Without Borders (EWB) in the past, and I was not familiar with their organization nor really what they did, this was a unique skills-based opportunity that I volunteered for to evaluate the operation of the Nueva Providencia micro-hydro system and to evaluate the needs to rehabilitate the Joyabaj decommissioned micro-hydro system. I am a geotechnical engineer and have been involved in the design and evaluation of many dams and water holding structures. It was my great honor to be able to use my skills and experience to assist in these evaluations so that these communities can take steps forward with improvements, such that someday they will be afforded the benefits of having civil infrastructure that provide clean water, abundant electricity, and transportation facilities.

The Joyabaj evaluation focused on the civil infrastructure components for the hydro-electric system: Dam, Canal, Forebay, Penstock, Powerhouse, and Tailrace. The hydro system had been idle and not used for around 20 years, though the main infrastructure components are still in place, some of them are damaged and in need of repair. I had the fortunate opportunity to work directly with colleagues Andy Carr and Jan Spies for several days, while we walked, surveyed, measured, documented, and assessed the structures and then developed a repair plan to restore the infrastructure in order to supply sufficient water back to micro-hydro turbine. The diversion dam is a run-of-the-river concrete gravity dam built in the 1960s, approximately 13 feet tall, with an intake structure to divert water from the river into a canal approximately 1,300 feet long to load a forebay and penstock that powers the micro-hydro turbines.

Inspecting the Diversion Canal Wall Repair with Jan Spies and Andy Carr.

Inspecting the Diversion Canal Wall Repair with Jan Spies. and Andy Carr

The existing infrastructure survived the relatively large 1976 Guatemala Earthquake, as well as several hurricanes, giving indications that the civil works were well-designed and well-built, though given their age and lack of maintenance several repairs and upgrades are required to bring the system back online. This includes several concrete walls that will have to be replaced or repaired, corroded or missing gates will have to be replaced, and the emergency spillway for the forebay will need to be improved to safely handle design flows. In addition, there is significant scour under portions of the canal that will have to be addressed and monitored. The work will take considerable effort given the relatively poor access to the site, requiring that almost all of the work will be manual labor without mechanized equipment. One of the more surprising elements in the evaluation was related to the cost estimate, as the labor is by far the least expensive aspect of the cost estimate, with laborers in this region earning only $6 a day on average – a month of labor is less than $200 per person.

Nason with Kata, a native Guatemalan who served as our cultural guide for the week.

Nason with Kata, a native Guatemalan who served as our cultural guide for the week.

It was an honor to work with diverse skills, nationalities, and perspectives brought by the team. I am looking forward to learning how these communities improve in the future, and working with members of the team on future projects.

 

 

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