Emergency Works at Calabazas Raw Water Intake San Sebastian, Puerto Rico

Client: Puerto Rico Aqueduct and Sewer Authorithy (PRASA)

Contract Period: 2018 (Project Duration: 6 months)

The Calabazas Raw Water Intake (RWI), located on Río Culebrinas, currently serves the 3-mgd Calabazas Water Treatment Plant (WTP) in San Sebastián. The intake is composed of a concrete gravity dam connected to pump pits. Floods in Río Culebrina associated with the passing of Hurricane María on 20, September 2017 caused collapse of a gabion wall placed at the intake wall to provide stabilization.

GLM personnel visited the site shortly after the hurricane to assess the damage and define a remediation action. The main damages observed were the collapse of a gabion revetment on the river bank adjacent to the intake. Due to the collapse of the gabion wall, the river now flows to the left side (away from the main channel), eroding and forming a new channel, causing the damage of the existing river weir left abutment. In addition, one of the intakes screens was totally destroyed due to the debris entering the intake.

Due to the damaged observed, an emergency work was required to guarantee the water supply to the filter plant. The purpose of the emergency project was to replace the collapsed gabions with stone revetment to ensure the intake structure's stability, repair the damaged abutment of the river weir and the damaged screen.

GLM was contracted to develop construction drawings and specifications for intake repair.