Piedras Blancas, Costa Rica

Piedras Blancas is a small village of palm plantation workers located in the Osa Peninsula, approximately 10 miles east of the Gulf of Dolce and 110 miles from San Jose. The village consists of 157 tightly packed homes with a municipal water system, curb and gutter storm drainage system, sidewalks, and paved roads. However, there is no centralized waste collection system. Instead, residents have septic tanks, some concrete and some earthen made, with greywater (from sinks and washing machines) typically being discharged directly overland and reaching the storm sewer system. Flow ultimately ends up in the Piedras Blancas River which then flows to the Gulf of Dolce.

A septic hauling service comes to the development 3-4 times per year.  The charge of the clean-out service ranges from $40 to $120 per home, depending on the number of homes being serviced that day and how thoroughly the tank is cleaned out.  The number of service providers is very limited and they have a long way to travel to the nearest treatment system, contributing to the high price of pump-out service. It is estimated that less than 30% of homes utilize the pumping service.  The remainder either have never serviced their tank, do not do it routinely, or their tanks are inaccessible. This inevitably results in tank overflow or routing of septic systems to the curb and gutter instead of leach fields, threatening public health.

Sharon Alfaro, a Piedras Blancas resident and GWS contact, who has been passionate in helping us to resolve wastewater issues, has worked to teach village members and children about the importance of clean water and proper sanitation. She has gone door to door to collect signatures from residents supporting construction of a treatment plant. Residents signing agreed to pay for an increase in their monthly water bills in order to maintain the system once it is in place.

Piedras Blancas was the subject of the 2015 Student Design Competition. The designed centralized wastewater treatment system was adapted and completed by local Costa Rican consulting engineer RQL, ensuring the design complied with Costa Rican codes. It was then submitted to government authorities for approval for construction.

An obstacle delaying final implementation has been land acquisition for the plant due to zoning issues. Currently, the land selected is owned by the Osa Municipality. It will be necessary to transfer land ownership to the ASADA, the local water authority, and re-zone. GWS is currently assessing two different options: (1) work with RQL to rezone land and transfer land ownership, or (2) purchase a different site. One potential site is owned by a community member and ASADA Board Member who is supportive of the project. Correspondence continues to move this project forward and GWS is confident that the project will receive “go” status.

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