Amanda Morris
November 20, 2004
Preliminary Report and Cost Estimate for Proposed Improvements to the
Water Supply and Waste Disposal Systems in Puerto Ayora, Sta. Cruz
I. Past Record
Few of the Galapagos Islands have fresh water, and those
that do, get water from rainfall or groundwater. Santa Cruz is unique
in that it has sufficient quantity of water to sustain its current human
population; however, the water quality is problematic. Santa Cruz’s
fresh water supply is pumped from 25 m underground by 7 electric pumps each
with a capacity of 20 HP. These pumps do not function in coordination
with one another, causing inconsistent flow rates. Seawater often mixes
in with the water source, so the water’s chlorine concentration is too high.
50% of the water is then lost due to leakage in the pipelines.
In the city of Puerto Ayora, the water is contaminated
with bacteria because no sewer system exists and most residents dump their
waste into two crevices that carry water to the city. There have been
several cholera outbreaks in the past as a result.
Each house is equipped with its own small pump with a
capacity of 0.5 HP because the pressure in the water grid is not sufficient.
Water is only pumped from 6 am to 5 pm. The city has a water purifying
factory that produces 800 m3 per day for cooking and drinking, but most of
the drinking water is imported.
II. Proposed Improvements
a. Construction of sewer system: Most desirable location of sewer is in center
of street because convenient to connect to houses on either side of street.
House sewers drain to it by gravity. Install at depth of 8 feet to
make room for basements that are 6 feet deep and house connections and pipes
2 feet deep. Other, already existing subsurface installations like
water pipelines and electrical wires muse be considered. Pipes should
be at least 8 in. in diameter to prevent blockage. Take advantage of
gravity flow to reduce number of pumps required. See Figure 1.
b. Construction of Solar Aquatics System for sewage-treatment plant: Capable
of treating 4500 m3/day, servicing 100 to 20,000 people, appropriate for
Puerto Ayora with pop. less than 10,000. Uses aquatic environments
with plants, snails, bacteria, and other microorganisms to metabolize or
bind up wastewater. Comprised of 10 aerated translucent tanks and an
anoxic marsh housed in a greenhouse. Produces fewer, more stabilized
solids, high quality effluent and provides a buffer against accidental toxic
discharges to sensitive receiving environments. Potential for water
reuse. See Figure 2. Potential sites for plant: northwest of
Laguna de las Ninfas or east of the city, near the road to the Charles Darwin
Foundation and Galapagos National Park. Both sites are advantageous
because they make use of gravity flow and are on the periphery of the city.
Laguna de las Ninfas and __ Bay (east of Academy Bay) are potential sites
of purified discharge. Septic tanks need to be installed for each household.
c. Installation of desalinization plant: Construct plant between well and
town that employs either thermal distillation or ion exchange techniques
to convert saline water (or reduce chlorine concentration). Thermal
distillation functions at 115 F and creates potable water but does not remove
all bacteria. Ion exchange is good for treating water with less than
4000-5000 mg/l dissolved minerals. If desalinization plant could also
treat water to maintain correct relational levels of pH, alkalinity, and
CO2, corrosion of pipes would be prevented.
d. Reform water distribution pipelines: Retighten lines to reduce loss of
water due to leakage. Examine joints at pipe junctions and make necessary
reparations. (Leakage is to be expected, even more so in unstable soil
or rock. 15-40 gpcd loss is acceptable.) Install meters on service
pipes or in house basements. (PVC pipes that were installed to street
mains to house piping are fine because they resist corrosion.)
e. Repair of pumps
III. Conclusions
The most crucial improvements needed in Puerto Ayora are
the construction of a sewer system and a sewage-treatment plant. Uncontrolled
waste poses an enormous hazard to human health and is an even more serious
problem in such a sensitive environment as the Galapagos. To diminish
these problems, sewer systems and waste-treatment plants must be built.
Solar Aquatics System is well-matched to Galapagos because of its green image,
efficiency, and potential for water reuse. Water reuse and conservation
will become even more important as population grows and adds stress on the
water resources. Unnecessary water loss can be reduced by preventing
leakage in the pipelines. Meters and measured cost will encourage consumers
to reduce superfluous water usage. Water flow will be made more efficient
and will reach more houses with more efficient pumps. Finally, better
water treatment plants and desalinization plants are needed to improve the
quality of water flowing into homes. The recommended improvements can
be applied to other cities in the Galapagos. For example, leakage and
waste pollution are also problems in San Cristobal.
IV. Estimate of Cost
V. Bibliography
Hardenbergh, W. A. and Edward B. Rodie. Water Supply and Waste Disposal.
Pennsylvania: International Textbook Company, 1963.
Ley, Deborah. An Assessment of Energy and Water in the Galapagos Islands.
http://galapagos.solarquest.com/documents/SandiaGalapagosReport200307.pdf
“Puerto Ayora street map.” www.TheBestofEcuador.com. http://www.thebestofecuador.com/map_payora.htm
“Solar Aquatics System.” OCETA Environmental Technology. http://www.oceta.on.ca/profiles/earthtech/icon.html