Spring Development

The diorite bedrock springs are groundwater discharge points that are fed by groundwater flow in fractures.  While the water table is high (early in the dry season), the hydraulic gradient (i.e., slope of the water table) is steep, and the discharge at the springs is greater than late in the dry season.  It may be possible to prolong the discharge at the springs by impounding water at the spring vents and artificially "backing up" groundwater in fracture storage. 

To the extent that groundwater discharge is increased by leakage in the water systems, fixing leaks in the distribution system will likely also prolong discharge at the diorite bedrock springs further into the dry season.

The Quarry Springs should be developed similar to the development at the Habbour and Kamera springs.

Source Area Protection

Source area protection is already in place at the Habbour Spring.  Source water protection measures should be developed soon for the West Side Spring.  Although present land development is minimal, source water protection measures should be identified for the Kamera and Motema springs.

Distribution System Improvements

Standards (e.g., depth of burial, gravel bedding, armoring at high-traffic areas, etc.) should be developed to ensure durable placement of water piping.

Tapstands should be developed in the south village area, perhaps from the West Side and Quarry springs.

System Storage

System storage should be developed for each spring source.  The system storage should be sized appropriately to capture one day's flow at each, respective spring.  Storage at the respective shpings should be deisgned to limit  the spring discharge by managing the hydraulic head. 

Water can be conveyed to the existing tapstands by improved piping.  System storage should be provided at each tapstand in order to meet peak demand.  Flow into system storage at the tapstands should be controlled by a passive, level-sensing float valve so that excess water is left at the respective spring catchment.

Disinfection

Chemical disinfection should be made available to all villagers.  It would be beneficial to provide passive, gravity-operated disinfectant dispensers at the tapstands.  Maintenance of the disinfectant dispensers could be provided as in-kind service by qualified villagers.  Sources of funding for chemical disinfectant supplies should be sought and/or locally developed.

Fees and Funding

Villagers must be educated on the importance of maintaining funding for the operation and maintenance of the water systems.  Opportunities for in-kind labor or services by low-income villagers should be developed.  One potential source for in-kind service would be non-manured cultivation of food crops in the source water protection areas upslope from the springs.

New Source Development

 The diorite bedrock springs are located in similar geomorphic settings along the valley wall above the village.  Candidate areas have been identfied at which horizontal drive points could be placed in order to capture some of the groundwater flow which now reports in the subsurface to the Garden Spring.  These horizontal points could be manually constructed.  A "shot-hole" drilling rig was observed in the Quarry, apparently left behind by the quarry operator.  This rig would be ideal for constructing horizontal drive points, if it could be rehabilitated. 

Hydrophilic indicator vegetation;  potato (left) and cassava (right)

Some differences in vegetation at spring and seep areas have been observed, and vegetation may be useful in identifying candidate drive point locations.  Satellite photographs are presently being obtained to facilitate remote-sensing analysis of potential drive point locations.

Abandoned shot hole rig         Quarry highwall seep

The quarry source should be developed.  A good approach to utilize this source effectively would be to construct shallow collector trenches above the quarry highwall, convey the water to system storage at the collector trench using hydraulic head to limit the instantaneous discharge, then convey the water through well-placed piping to tapstands in the south village.

At this time other alternatives seem more feasible than the development of the Motema Spring(s), which now provide water to the village of Dodu.  The quality and quantity of water from this source is signficant, and measures should be taken to provide source area protection to this source so that water quality and quality is unimpaired in the future.  Although this alternative would be moderately expensive, it appears that a significant quantity of good-quality water could be provided by gravity flow from the Motema Spring(s) to the village of Baoma.

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