Observations on Water System and Pipeline Performance in the Limon Area of Costa Rica Following the April 22, 1991 Earthquake

Keywords: Costa Rica Earthquake, April 22, 1991, Post-earthquake Investigations, Water Supply Systems, Lifelines, Water Treatment Facilities, Ground Effects, Water Distribution Systems, Seismic Performance, Damage, Buried Pipelines, Oil Transmission Lines, Wave Propagation Effects, and Earthquake Engineering.

Abstract: This document focuses on earthquake damage to water and oil pipelines, water supply, and water treatment following the 22 April 1991 Costa Rica earthquake. The moment magnitude 7.5 earthquake occurred approximately 40 km south-southwest of Limon, and resulted in a coseismic uplift of up to 1.5 meters along Costa Rica's east coast. This report also provides an overview of the engineering aspects of the event and recovery activities. Turbidity in the watershed which provides Limon's primary water supply increased to as high as 2.4 percent solids, making it extremely difficult to treat. In addition, the water treatment plant was damaged by the earthquake. Cast iron, ductile iron and reinforced concrete cylinder pipe water transmission lines were damaged by both wave propagation and permanent ground deformation. Water distribution piping, also including PVC and galvanized iron, was similarly impacted. Documentation and evaluation of that damage is described, and compared with empirical estimates from previous earthquakes. Twin 150 mm (6 in), 100 km long, oil transmission lines suffered only a single failure from wrinkling. A description of the pipelines and the failure is provided.