MARIKINA CITY, PHILIPPINES—If not for the square metal manhole covers laid strategically on the ground, a stretch of greenery on an easement by the Marikina River in Barangay Industrial Valley Complex (IVC) looks for all the world like a park where children run around on balmy afternoons.
The area actually hosts a no-nonsense underground wastewater treatment facility, the Olandes Sewage Treatment Plant (STP), which can process up to 10 million liters per day of domestic wastewater from the homes of some 40,000 residents in the surrounding communities.
The wastewater from the communities surrounding the Olandes STP flows into the underground facility and undergoes the following cleaning process before it is released into the Marikina River:
- Solids are screened and de-gritted to separate the debris from the liquid
- The filtered liquid is aerated in an equalization tank and infused with oxygen
- Micro-organisms degrade the remaining organic matter in the liquid
- The liquid undergoes further clarification, disinfection, and chlorination
At the end of the process, the water is so clean that local residents have taken to bathing in the outfall, catching the clear water before it joins the river flow.
The black sludge, a final end-product of the treatment process, is fed into a dehydrator to squeeze out any excess water. It is then hauled by a contractor to Tarlac where it is used in demo farms for sugarcane cultivation to condition the soil damaged by lahar spewed by Mt. Pinatubo when it last erupted in 1991.
With a $63 million loan from the World Bank under the Manila Third Sewerage Project (MTSP), Manila Water Company (MWC), a private water concessionaire, has built several sewage treatment plants in Marikina City, San Mateo in Rizal, Magallanes in Pasay, and the FTI Compound in Taguig City.
Rey Ancheta, World Bank Operations Officer for Sanitation, explains that the project aims to reduce the pollution in Metro Manila waterways and the Manila Bay, as well as reduce health hazards caused by human exposure to sewage by expanding the septage-management approach of the Metropolitan Waterworks and Sewerage System (MWSS).
This is in line with the requirements of the Clean Water Act of 2004, the Philippine Medium-Term Development Plan targets from 2004-2010, and a recent Supreme Court ruling ordering government to clean up Manila Bay.
When completed, the project will provide sewerage services to 3.3 million residents the cities of San Juan, Mandaluyong, Marikina, Pateros, Pasig, Taguig, some towns in Rizal and parts of Makati and Quezon City.
In conjunction with other projects in the pipeline for the Marikina River Basin, the Olandes STP helps the city in its drive to clean up the 11-kilomenter river.
Today, while the river still overflows during heavy downpours, what used to be a garbage dumping ground reeking with domestic and industrial waste is a flowing waterway lined on both banks with parks and playgrounds.
When MWC approached the city of Marikina about building a sewage treatment facility on a tight easement along the river, the city government required that it follow the city’s design for the river. That is why, aside from the park-like atmosphere, Manila Water has built a jogging lane that will connect to the riverbank’s other facilities.
Since the easement area is small and is perennially flooded, the STP was designed to be submersible. The main processing plants are located underground while its support facility, which houses sensitive equipment such as the blowers and the control panels, is built on stilts.
The design and construction of the facility was contracted out to the JFR Engineering Corporation for completion within a year under a P262 million contract funded by the World Bank under the MTSP. The contract was awarded in July 2008 and construction was completed in August 2009.
The facility received its baptism by water on September 26, 2009 when, still in its commissioning stage, the STP withstood the onslaught of Typhoon Ondoy which inundated Metro Manila, causing destructive flash floods. Creeks and rivers rose to unprecedented levels, including the Marikina River, destroying homes, public infrastructure and vehicles, and taking many lives.
But the Olandes STP remained intact, its sensitive electro-mechanical and instrumentation equipment in the building on stilts remained dry. The facility incurred only minor electrical damage, including the replacement of a generator set. The underground tanks were safe, requiring only cleaning and de-silting, and the landscaping had to be redone. The Olandes STP went into regular operations in April 2010.
Says John Roome, World Bank Regional Director for Sustainable Development Network - East Asia and Pacific: "This excellent facility is an important part of the greater effort to clean-up Manila Bay."
He added, "It was encouraging to see that it was well designed to be resilient to flooding wrought by Ondoy. We look forward to working with Manila Water and we will continue to support its efforts in improving the environment."