ANGELES CITY- The occurrence of sinkholes after the recent destructive earthquakes in Bohol province has raised fears among local folk that such threat could arise from over extraction of underground water for more golf course and water theme park projects at nearby Clark Freeport.
Danilo Uykieng, director of the Mines and Geo-sciences Bureau (MGB) in Central Luzon, admitted his agency does not have data on sinkhole threats at Clark where investors are known to consume huge volumes of water daily.
Clark hosts the Mimosa and Fontana resorts which have 36-hole golf courses each, amid the on-going construction of yet another one by the Korean firm Donggwang. Fontana also has a huge waterpark while the BB International Leisure and Resort Development Corp. is also set to construct another, data from the state firm Clark Development Corp. (CDC) showed.
Uykieng said, however, that an “x-ray” of lands, using a “ground penetrating radar,” could be done to find out if there are potential sinkholes in Clark. Such a device is available at the land geology division of the MGB central office, he added.
He said that his agency has no role in water usage at Clark as it is under the Bases Conversion Development Authority (BCDA) and, in cases of huge water consumption, it is the National Water Resource Board (NWRC) which grants permits, together with CDC.
At least 100 sinkholes were found in Bohol after it was hit by a 7.2 magnitude earthquake last Oct. 15. A sinkhole is a vacuum or cavern beneath the ground or topsoil which could collapse during an earthquake or a heavy rain.
Uykieng said that such underground vacuum could be created by too much extraction of groundwater and that sinkholes are not uncommon in areas where the ground is mostly of limestone.
“Limestone is porous and brittle and it tends to collapse,” he noted. But Red Fuentes, chief of the environment department of the CDC which manages the Clark Freeport, debunked reports that lands covered by Clark and nearby cities and towns are largely of limestone.
“Lands at Clark, Angeles and other areas around Mt. Pinatubo are of pyroclastic materials that have hardened for centuries,” Fuentes said. He downplayed fears on sinkholes, saying they are not likely to occur locally.
He also said that while studies have shown that some coastal towns in Pampanga which also stand on pyroclastic materials are sinking, this was attributed to over extraction from their aquifers or underground water source.
Fuentes debunked reports that the aquifer at Clark is being overused, citing figures indicating that the consumption of water by even golf courses could not lead to a vaccum underground.
“There were three studies that indicated that the Clark aquifer could yield as much as 90,000 cubic meters daily without drying up because this is also the rate with which it is recharged with water from the rains,” he said.
He recalled that two of the studies were done by the firm Woodward and Clyde and Clark Water Corp.
Fuentes said that at present, investors at Clark consume only 24,000 cubic meters daily. “Even the 36-hole golf courses at Mimosa and Fontana are limited to only 3,000 cubic meters daily and that is also the limitation imposed by their ECC (environmental clearance certificates),” he added.
He also noted that Texas Instruments and Samsung, so far the biggest water consumer at Clark, limited their consumption to only 6,000 cubic meters per day by recycling water.
