The New England Branch Designs an Off-grid Water Supply for a School in Rural Liberia
In Spring 2014, a group of volunteers from Geosyntec’s New England Branch began designing an off-grid water supply system for a school in rural Liberia. The project arose through the vision of a group of Liberian refugees who had relocated to Providence, Rhode Island and wanted to build a school near the village they had to leave behind during the Liberian Civil War.
The Geosyntec team who worked on the project included Kathy Phillips (now in the Santa Barbara office), Jon Gillen, Chris Arsenault, Chapman Ross, David Adilman, Carl Elder, Scott Luettich, and Doug Larson.
The DesignThe overall design concept consists of a boarding school on a 15-acre campus that includes the following components:
- School buildings for grades K-12
- Separate facilities for vocational training
- Dining hall/Multi-purpose building
- Residences for appx. 200 Students and staff
- First aid/health section
- Design and construction of primary campus water supply and a hand pump well for community access
- Sanitation facilities for residences as well as daytime students
- Off-grid electricity
The initial phase of construction includes the facilities for elementary grades, vocational classes and a faculty/guest house. The Rotary Club International has provided substantial funding for the work, supplemented by private donations.
The water supply and sanitation system design developed by the Geosyntec team includes a solar panel array to power a downhole water pump, a chlorination system, a water tower (foundation and structure), a water distribution system, and a septic system to handle wastewater. The system is designed to eliminate the cycle of water contamination that occurs when insects contact waste and then contaminate food and clean water sources. This water supply system prevents such contamination, thus providing a healthy school environment, and eliminates the need to haul water by hand so students can focus more time on their school work.
A hand–pumped supply well was the first installation so it could supply all of the workers with clean water for drinking, washing, cooking, and it provided water during the construction process for making cement. It also provides a clean, reliable, long-term water supply for the community.
The automated pumping system for the school includes a 90-foot deep supply well fitted with a Grundfos SQ-Flex submersible pump, solar modules to power the pump, and a 1500-gallon water storage tank mounted on a 30-foot water tower to deliver steady water flow throughout the day.
The design for the solar panel system considered the rainy season, assuming 35% efficiency under rainy conditions. With this reduced efficiency the panels will still provide enough power to run the pump at 5 gpm for 6 hours (enough to fill the storage tank during useable daylight). The solar array includes 6 panels, providing a total voltage of approximately 240 VDC with amperage varying based on the amount of sunlight. The pump is designed to run with varying amperage, producing greater flow as amperage increases.
The chlorination system is similar to that of a swimming pool chlorination system and is designed for simple maintenance. The water treatment train includes a pressure regulator to limit the pressure output from the pump, a 140-mesh filter to remove particulates, a chlorination chamber that holds chlorine tablets to treat the pumped water, and a valving system to regulate the percentage of flow that passes through the chlorination chamber (and thus the total amount of free chlorine in the water stream). The water treatment components are located inside a masonry block pump house near the supply well.
The Geosyntec team also designed the foundation and steel support structure for the water tower. The foundation consists of four concrete footings, each exerting less than 1 ton per square foot on the underlying soil when the water tank is full, and the support structure consists of 4-inch diameter vertical steel pipes with cross-bracing for stability. The storage tank has a closed top and the vent pipes are fitted with mesh screens to stop water contamination from insects.
The septic system design was based off the "Residential Onsite Wastewater Treatment Systems Design Handbook" from the New York State Department of Health Bureau of Water Supply Protection. The Liberian work crew actually made the septic tank much larger than required, thus reducing the frequency needed for septic cleanouts..
System ConstructionIn April 2016, Doug Larson traveled to Liberia to assemble the systems the Geosyntec team had designed. Doug is a Senior Principal Engineer based in Massachusetts who manages Geosyntec's six New England Branch offices, with a combined staff of over 70 engineers and scientists. Doug worked together with Jon Rossman (the construction manager for the project) and a crew of approximately 30 Liberian workers to install the water supply components and build the septic system. The excavation work for the foundation construction, underground piping and septic system was all done by hand. The project funding allowed for the purchase of a hydraulic block-making machine that creates up to 1200 interlocking masonry blocks per day using sand obtained on-site mixed with about 10 percent cement – a very cost-effective means of building construction that will also provide a source of income for the community after the school project is complete.
What's NextThe project includes several micro-economic development aspects to provide long-term support to the school and the community. Twenty of the local work crew were trained in the use of the hydraulic block-making machine so they can use it to generate income after the school is completed, returning a portion of the revenue to the school to support operational costs. Some of the school property has been set aside for a local organization of women to grow produce to sell at the local market to provide income for their families and for the school. The group adopted the name GROW (Gbarnga Rural Organization of Women). The seeds for the crops were provided by a U.S.-based organization called Hope Seeds.
As funds become available and the program grows, the project will expand further to include:
- Grades K-6
- Expanded vocational training facilities
- Guest houses
- Athletic fields