The Pantabangan Dam is proposed to be built seven kilometers upstream of Pampanga River from the town of Rizal, Nueva Ecija. It shall perform useful functions for the Hydroelectric Plant, Flood Control, Domestic and Industrial Water Supply, Aquatic Resources Conservation and Recreational Facilities. It also renders other functions, namely:
1.1 To demonstrate the most suitable water management to expand irrigated area
1.2 To adopt practical cropping pattern to increase production
1.3 To organize farmer and users into irrigation associations for better implementation of water distribution ; and
1.4 To serve as a training center for the job training of NIA personnel and farmers
Because majority of the irrigation systems in the Philippines use the run-river diversion types of supply water for rice crops, these systems depend primarily on the flow of water from the river and availability of water from the watershed. The system is enough to supply the requirements of certain areas so that they do not find the necessity to have water management until problems arise such as sudden decrease in the flow of water because of the denudation of forest watersheds.
Other problems are after the rainy season when the flow of water from the river decreases sharply which affects the capacity of the systems for double cropping.
These situations create the problem of rice production to support the country’s rapidly expanding population. To solve this problem, the Pantabangan Dam is proposed to be constructed, primarily as a good source of irrigation, and secondly, as a source of power generation.
Description of the Solution
With the help of the Development Bank of the Philippines, the National Irrigation Administration searched for areas with the best potentials. In 1960 the U.S. Bureau of Public Roads (USBPR) was tapped to undertake feasibility studies on the development of the Pantabangan Dam which would prevent floods, conserve water for irrigation and generate power for a Hydroelectric Plant.
In 1961, the U.S. Agency for International Development (USAID) referred to its Washington Office a cooperative project/proposal with the National Economic Development Authority to conduct a comprehensive study of Philippine water resources and identify projects of greatest potentials for development.
This recommendation led to the signing of the agreement on October 25, 1962 between the United States and Philippine governments regarding funding, assignments of consultants, and agency participation in the proposed undertaking. On November 2 of the same year, the USAID jointly with the U.S. Bureau of Reclamation (USBR) agreed to push through the recommendations. Consequently in April 1963, survey work and feasibility study started.
By 1966, engineers of the Bureau of Reclamation under contract with the NEC-USAID came out with the feasibility report identifying USBPR as having the greatest potential for development. In 1968 of May, a joint technical staff was created by President Marcos to conduct further studies on the possibilities of reducing the cost estimated by USBR.
In June 1969, the Philippine Congress adopted R.A 5499 authorizing the construction of the Pantabangan Dam, its appurtenant structures and irrigation service facilities and providing local counterpart funds. Subsequently, in August of the same year, the world bank approved a $34 M loan to finance the foreign exchange cost of the project. The contract for its construction was awarded to Hydro Resources Corporation (CONSORTIUM of some Filipino Contractors). In 1972, Presidential Decree No. 35 set aside a Guarantee Fund of Php720 M to ensure the completion of the project including the funding for the power function and execution of further studies to expand the project benefits.
The Pantabangan Dam is about seven kilometers upstream of Pampanga River from the town of Rizal, Nueva Ecija. It consists of the two zoned earth full dams, the main dam and the ava dam embankment. It measures 1.61 kilometers long, 107 meters high from the riverbed, 480 meters wide at the base and 12 meters wide at the crest.
The Pantabangan Dam is designed with two tunnels, 30 meters apart at the bottom of the main dam’s left abutment, each measuring 576 meters long and 7 meters in diameter. Each has a design discharge of 1643 per second One of the tunnels supplies the irrigation needs of the service area while the other is for the future generation of Hydro-electric Power.
A concrete chute type spill way with design discharge of 4,200 cubic meters per second is located at the end of the ava embankment. It is 260 meters long and has four bays, three of which are gated, and the fourth, an overflow.
A connecting open channel sets across the ridge separating the main and ava reservoirs, at an elevation of 200 meters above sea level and measuring about 200 meters long and 60 meters wide. It will divert the excess water from the main reservoir to the ava reservoir and to the spill way.
The Pantabangan reservoir, consisting of the main and the auxiliary reservoir, submerges the town of Pantabangan and eight outlying barrios. It has a surface area of 8,420 hectares and is capable of impounding 3.08 million cubic meters of water.
The allocation of the reservoir space is 330 million cubic meters of flood storage, 17,353 million cubic meters storage for irrigation and domestic water supply, ineffective storage of 95 million cubic meters and 668 million cubic meters surcharge. The allowance for sedimentation is 130 million cubic meters.
Some 150,000 hectares of forest and range lands compose the watershed.
The Pantabangan Dam includes power generating units with the installed capacity of 100,000 kilowatts. Two units of 50 megawatts generators which could be installed at the downstream of the dam would add more than 70,000 kilowatts of dependable capacity and generate some 232 million kilowatt hours of electric energy annually.
The dam is estimated to cost Php720M to ensure completion of the project including the funding for the power function and execution of further studies to expand the project benefits.
Time of Completion
The dam is estimated to be accomplished within 3 years and 5 months starting March 3, 1978 and is to be completed by August, 1981.