Transco vice president for engineering design and construction Winifredo SM. Pangilinan said the project used a so-called bored pile foundation technology which has deeper and stronger foundations suited for lahar conditions. Soil instability is a major technical challenge in lahar-filled transmission line routes.
Pangilinan said the lines were relocated because the lahar flows have buried large portions of the steel towers and steel poles. In some areas, half of the steel towers were submerged in lahar.
As a result, the "lowered" lines have become unsafe for passersby and nearby residents since the lines no longer meet the required minimum line-to-ground clearance or the safe distance between the transmission line and the ground.
This situation, Pangilinan said, has also resulted in frequent line tripping due to increased proximity to growing vegetation underneath the lines.
According to Pangilinan, the multi-million peso transmission project involved three 230-kv lines: the Hermosa-San Jose, Mexico-Hermosa and Hermosa-Balintawak 230-kV transmission lines. A total of 42 steel towers and 30 steel poles with a combined length of 20 kilometers were constructed.
Transco president Dr. Alan T. Ortiz expressed satisfaction over the early completion of the project. – Donnabelle Gatdula