The Metropolitan Manila Development Authority (MMDA) has proposed the construction of rainwater impounding facilities inside Camp Aguinaldo to help ease recurring flooding along EDSA. The proposed design was released on Wednesday, 27 August.

Formally titled “Proposed Rainwater Impounding Facilities inside Camp Aguinaldo,” the project directly addresses the severe flooding that paralyzes major roads like EDSA during heavy rains and typhoons. The existing drainage system has been unable to manage large volumes of rainwater, resulting in dangerous ponding and severe traffic congestion.

The proposal calls for the construction of detention ponds that would temporarily store excess rainwater during downpours and gradually release it into the drainage system along EDSA going to Makiing Creek. This approach aims to prevent the system from being overwhelmed during peak rainfall.

The project will be implemented in three phases, covering a total catchment area of 172 hectares inside Camp Aguinaldo. The identified sites include:

• Phase 1: A 34-hectare section of the golf course near Gate 2

• Phase 2: Additional golf course areas near Gates 3 and 4

• Phase 3: A 79-hectare open space near Gate 6

For Phase 1 near Gate 2, the detention pond is designed with a 361-meter outside perimeter, a 4,650-square-meter area, an 8-meter depth, and a 37,200-cubic-meter capacity. It is engineered for a 25-year return period, based on a rainfall intensity of 15.6 mm per hour over 24 hours. Its capacity exceeds the calculated needed volume of 36,945 cubic meters. The drainage system will use reinforced concrete pipe culverts (RCPC) ranging from 24” to 42” in diameter.

The schematic diagram released by the MMDA outlines an operational plan using floodgates (FG-1, FG-2, FG-3, and FG-4). Under normal conditions, water bypasses the pond and flows into the lagoon toward EDSA. During heavy rains, floodgate FG-1 opens to allow floodwaters into the detention pond while FG-2 closes to contain it. After rainfall, pumps with a capacity of 0.3 cubic meters per second will slowly discharge the stored water—a process that could take about 34 hours with one pump or 17 hours with two pumps.

The comprehensive scope of works includes building the impounding area, an operations and powerhouse building, extensive drainage works, electromechanical systems, and landscaping for golf course restoration. A treatment facility is also under consideration, according to the proposal documents.

The MMDA noted that critical matters such as operations and maintenance of the facilities, inclusion of a treatment facility, and a memorandum of understanding or agreement between involved agencies remain pending.

The proposal also emphasizes that the detention pond must be emptied before rainfall events to maximize its storage capacity for incoming floodwaters.