Effects of In-stream Sand and Gravel Mining in Scour at Bridges in Puerto Rico

Abstract

Scour of bed material from around bridge foundations is the most common cause for the failure of highway bridges in the United States. In Puerto Rico, millions of dollars are being spent by the Puerto Rico Highway Authority (PRHTA) and the Federal Highway Administration (FHWA) in the rehabilitation and replacement of bridges identified as scour critical. On the other hand, in-stream sand and gravel mining has been an important commercial activity due to the increase of the Construction Industry during the 90’s. In Puerto Rico, these activities are regulated by law and a permit is required. The Department of Natural Resources is responsible for granting permits required for in-stream activities. The purpose of this study is to analyze if there is streambed degradation near bridges caused by sand and gravel extraction activities and if this effect is being considered during both, scour evaluation and the evaluation for granting permits by the DRNA. Key Terms - Bridge Scour Evaluation, In-stream Mining, Sand and Gravel Extraction, Scour, Scour Critical Bridge, Streambed Degradation.