Engineers Without Borders The Mirimar Project

1. Engineers Without BordersThe Mirimar Project Water Delivery Option: Collection of Rainwater Group Members: Chris Mohl Brian Quinn Sara Smith

2. Technology Concept • Rain Water Collection • The annual rainfall in El Salvador is about 1778 mm or 5.83 feet. • Developing catchment areas per house hold via the roof or ground catchments for the entire town. • We can construct a collection device (reservoir) to hold the appropriate amount of rain water needed. • The dimensions of the device would be determined based off the needs of the town. Examples of household systems

3. Technology Concept (cont.) • If size became an issue we could look at multiple systems to help accommodate the people. • The reservoir can be constructed using local materials, pending more research. • This concept is a common practice used in many third world countries. • Filtration is not a dire situation but, for the above ground system we would need a screen to prevent large debris and insects from getting into the tank. If we used the ground system we could use a slow sand type filtration. http://www.lboro.ac.uk/well/resources/fact-sheets/fact-sheets-htm/drh.htm Example of an underground catchment area.

4. Volume Of Water • Based off of the decision of 80 liters per person for 200 people in the town the volume of water needed is approximately 16,000 liters per day. In a year that equals 5,840,000 liters or 1,541,760 gallons. • When considering the rainwater collection option we can consider if we want this system to hold for the entire year or just the dry season. • Once a decision is made on that then we can determine the appropriate amount of rainwater needed to be collected/stored. • The volumes can/will vary but we can always consider having multiple systems. • If we did want to store water for an entire year then using a cylinder storage device then we are looking at a 52 foot radius and a height of 25 feet*. If we split this up into 3 systems then we would have a 30 foot radius and a height of 25 feet*.

5. Volume Of Water (cont.) • This is obviously very large numbers we are talking about so we could consider a tank per house hold. • A tank for an entire year for a household of 5 would approximately be a 10 foot radius with a height of 15 feet.* • Consider that this is looking at water for the entire year which may not be necessary. We could consider just enough for the dry season. If we do consider this approach then the numbers would come down substantially. *These numbers can be changed; this is only a rough estimate. Also keep in mind there can be multiple systems thereby changing the numbers.

6. Costs • When considering the cost we have to consider the exact design, materials to be used, and the labor. • Most of the cost would come into the materials and labor. • The materials can vary depending on if we do an underground system or a above ground. We could look in to look resources such as concrete or various plastics. Also, we should look into any types of metals that would be needed. • As suggested by last weeks speaker we should not bring everything down to them, instead see what they have to offer. • Common materials used in other countries include galvanized corrugated iron or plastic sheets, or tiles. Thatched roofs made from palm leaves (coconut and anahaw palms with tight thatching are best). Other thatching materials and mud discolour and contaminate (through rats) the rainwater.

7. Costs (cont.) • Unpainted and uncoated surface areas are best. If paint is used it must be non-toxic (no lead-based paints). Timber or bamboo is also used for gutters and drainpipes; for these materials regular replacement is better than preservation. Timber parts treated with pesticides to prevent rotting should never come into contact with drinking water • After last week it was properly determined that contributions from the town are vital to a successful project. Also this can help save major dollars if we can do most of the work locally. • Ways the town can contribute: -using local materials. -hiring local workers to help construct the reservoir. -working with the town on where the reservoir/reservoirs can go.

8. Costs (cont.) • In Brazil, the cost of a 30m3 cistern in rural areas of the Northeast is around $900 to $1000, depending on the material used. • In the Chaco region of Paraguay the capital cost of a 30 m3 cistern in Paraguay has been reported to be $2000, while the construction of a 6000 m3 cutwater cistern, including windmill-driven pumps and distribution piping, has been estimated at $8400. http://www.oas.org/dsd/publications/unit/oea59e/ch10.htm http://www.rwh.in/

9. Energy • Little/No electricity needed. • Just collect rain and store it. • Pumps and foul-flush?? • Energy needed to build and maintain system. • Town residents must keep the system clean and running correctly.

10. Environmental Impact • Little/No detriment to the environment. • Mostly building upon existing structures. • Using rooftops for collection and barrels next to houses for storage. • Making use of existing reservoir. • Needs no gas/electricity (outside of implementation) – no pollution. • Will need local materials for building.

11. EWB Water Guidelines Compliance • The system must include a foul-flush diversion • Must remove vegetation from above roof lines • Using sand filter and chlorine will provide sanitation within EWB guidelines @ EWB suggestion

12. Appropriateness For Mirimar • Maintains enough water for the dry season • Easy to maintain, as there are no technologically advanced parts • Maintenance may be too in depth, constant chlorination, and keeping the foul-flush clean

13. Summary • Pros: • Rainwater harvesting provides a source of water locally. • A rooftop rainwater catchment system is simple, and local people can easily be trained to build one. • The systems can be built to meet almost any requirements. • Improve the engineering of building foundations when cisterns are built as part of the substructure of the buildings. • Cleaner water to start out with. • Inexpensive to operate. • Construction, operation, and maintenance are not labor-intensive.

14. Summary (cont.) • Cons: • The success of rainfall harvesting depends upon the of rainfall – not a dependable source in droughts. • Leakage from cisterns can cause the deterioration of load bearing slopes. • Cisterns and storage tanks can be unsafe for small children if proper access protection is not provided. • Possible contamination of water. • Cisterns can be a breeding ground for mosquitoes.

15. References • http://www.lboro.ac.uk/well/resources/fact-sheets/fact-sheets-htm/drh.htm • http://www.oas.org/dsd/publications/unit/oea59e/ch10.htm • http://www.rwh.in/