S&T and rehabilitating abandoned mine waste dumps

By LEILA C. AMERICA AND PAULA BIANCA Z. FERRER
PCARRD

Areas for mining operations, when abandoned, are likely to harm the drainage system in watersheds, making them conduit for toxic elements downstream, unless they are rehabilitated. 

To address this problem, researchers from the Department of Environment and Natural Resources, Region 8, studied possible rehabilitation measures to restore the productivity of abandoned mine waste dumps and open degraded areas and to eliminate their potential as water pollutants through the use of certain vegetative species and other strategies. 

Assessed for their growth and survival were four plant species expected to provide vegetative cover on the ground: talahib (Saccharum spontaneum), mora grass (Vetiveria zizanioides), wedelia (Wedelia trilobata), and pinto peanut (Arachis pintoi).

The study conducted in Bagacay Mines in Hinabangan, Samar, one of the seven abandoned mine sites in the Philippines that need immediate rehabilitation, once completed, may be applied to or become basis for other abandoned mine areas.

Researchers observed that after a year, mora grass survived the highest at 89.33 percent, followed by pinto peanut at 61.33 percent, wedelia at 59.33 percent, and talahib at 39.33 percent, the lowest despite its being a native species in the area.

Also observed in the study were the physical signs of reaction of the said vegetative species to their environment due to limiting factors in the site such as soil moisture, hence the purplish brown discoloration in the leaves of wedelia, yellow-green in mora grass and pinto peanut; and rusty brown discoloration in the leaves of talahib.     

The study also looked into other strategies to facilitate growing of vegetation in the site such as mixing limestone with mountain soil to neutralize soil acidity and the use of mulching materials such as rice straw and grass straw to conserve soil moisture, and to serve as organic matter once decomposed.

Mulch is a cover placed above the soil to protect its surface from the impact of raindrops, prevent erosion, and serves a number of other uses. For this purpose, rice straw is suitable as these are merely left as waste in rice fields and also abound in hills and roadsides. 

This research was presented during the R & D Symposium in the Visayas Consortium for Agriculture and Resources Program (VICARP) wherein the Philippine Council for Agriculture, Forestry and Natural Resources Research and Development (PCARRD) was one of the evaluators. #