for the Galapagos Islands
By Ricardo Toledo,
Proctor & Redfern International Ltd.
The Galapagos Archipelago has been known for its unique ecosystem and biodiversity ever since Charles Darwin developed the founding principles of his Evolutionary Theory in the 1800s. Today the islands are an important area for ecological conservation and continue to be the subject of international scientific research.
The Island of Santa Cruz is the focus of a rapidly growing tourism industry, and is also the home of the world renowned Charles Darwin Research Institute. The city of Puerto Ayora, the main populated centre of the archipelago, is contained within the boundaries of the Galapagos National Park.
The rapid demographic growth has created an extraordinary pressure on the island's basic water supply and sanitation services. This represents a threat to human health and to the environmental integrity of the area as a result of both surface and subsurface contamination.
Proctor & Redfern International Limited (PRIL) was retained by the Ecuadorian Government to identify and design the preferred water supply and distribution, as well as sewage conveyance, treatment and disposal systems for the city of Puerto Ayora on the Island of Santa Cruz. The preferred water supply and sewerage treatment systems must be compatible with the surroundings, while preserving and enhancing ecological and sociological conditions.
The project is divided into four phases. Phase 1 provided for a diagnostic report which identified the conditions of the existing systems available on the island. Phase 2 included the preparation of an Environmental Study Report (ESR). The ESR was utilized as the decision-making methodology to identify the optimum solutions for wastewater treatment and disposal. The Feasibility Study, together with the Environmental Impact report have been submitted to the client for review and approvals. Phases 3 and 4 will be dedicated to final design and tender documents for construction.
The analysis of the proposed new drinking water distribution system involved modeling of both system pressures and quality using EPANET.
Groundwater investigation was aimed at replacing existing water sources, which have high chloride content and poor bacteriological quality. The drilling of an exploratory well was challenging from both technical and logistics perspectives due to the remoteness of the site and the volcanic formation of the island.
The identification and development of alternative wastewater disposal solutions included a marine survey and underwater inventory of habitat and biota in the adjacent Academy Bay to determine the candidate outfall locations.
Modeling of effluent plumes was conducted for various different multi-port diffuser designs using the EPA's Cormix Model. Further oceanographic studies to measure currents, water stratification and plume dispersion will be undertaken to confirm modeling predictions.
The Solar Aquatics System, a low-cost, low energy biological and ecological treatment system, is the sewage treatment option being considered for this environmentally sensitive area.