Laguna Lake Development Authority Case Study on the Creation of Four Polder Island

Development of a drinking water reservoir

The most southern island is proposed to become a drinking water reservoir to provide a continuous 400 MLD water supply to address the expected inadequate reliable water supply in the year 2006.  This could serve as interim for the proposed Agos River Multi-Purpose Water Resource Development  project.  Afterwards, this polder could be converted into valuable land.

In combination with operation of the Napindan Hydraulic Control Structures (NHCS) the duration and level of increased salinities will be controlled (still allowing for the assumed beneficial effects on primary production and consequently fisheries).  The reservoir and associated drinking water treatment plant is relatively easy to realize, overcomes problems related to conflicts of interests andideally connects to the existing distribution network.

Sanitary landfill

The north polder island could facilitate a new sanitary landfill for Metro Manila and nearby towns.  In combination with improved garbage collection scheme’s, segregation and recycling it could solve the solid waste related problems for the next 50 years.  The site can also serve as containment area for sludge, polluted sediments, industrial waste and temporal drying fields for dredged clay material and light industrial parks.

Gradually the island will be converted into a recreational area (on top of the landfill).  Advantages are related to:

• the thick layer of impermeable clay underneath the site

• the size of the sanitary landfill island (500 ha)

• the accessibility and close distance to Metro Manila

• the controllability of the leachate from the land fill due to the planed wastewater treatment plant

• its offshore position (and law traffic impact and hinder to the surrounding area) and

• the availability of cover material within the project area (as a result of maintenance dredging)

Social housing

By dedicating the new land (1700 ha) for social housing congestion related problems in the dense adjacent coastal area can be reduced.  The inner two islands could provide space and job-opportunities to some 350,000 people.  It would include a commercial fisherman village, institutional and commercial parks, recreational aea and sport complex and light industrial zones.

Interceptors and waste water treatment plant

To improve the water quality and ecology of the Laguna de Bay, collection and treatment of all domestic and industrial waste water is proposed  in the entire coastal area.  The treatment plant at the most northern polder island will also be used for the treatment of wastewater from the new polder islands and for treating the leachate from the landfill.

Construction of the Circumferential Road 6 (C6)

To solve the problem of the congested Southern Express way and the adjacent municipalities the construction of the C6 a four-lane divided highway which intersects four proposed interchanges located at Tagig, Sucat, Alabang and Biñan) is proposed.

Shoreline restoration

To improve the natural and living conditions along the shoreline, the following aspects are considered:  fishponds for endemic species, green buffer zone, recreation activities, nature development/ ecologic embankments, establishment of a Laguna de Bay eco-museum.

Environmental dredging

The need for dredging the downstream part of the tributaries is twofold:  the dredging of garbage and contaminated material attached to fine particles and dredging for maintaining the river outflow (flood control).  The water system around the polder islands will be maintained at a certain depth to improve the water quality and allow for different user activities (fisheries, recreation, nature development, etc.) The dredged clay material can be used for raising the land elevation and as cover material for the landfill.

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