What Happened Last Time – Lessons Without Experience, Chapter 1

ABSTRACT: What happens when there is not enough information about the ground conditions or when designers do not refer to records of past experience? Two case histories involving dewatering for excavations in unconfined aquifers adjacent to rivers are presented. The first concerns an addition to a sewage treatment plant where the geotechnical investigation was lacking and the relevance of a known condition was not investigated. This resulted in the redesign of the plant addition and the operation of a complicated dewatering system in conjunction with sheeting for a pumping station excavation. The second concerns an addition to a pumping station where significant lessons about past experience were not investigated. This led to a claim in which both contractor and owner blamed each other for past experience.