Density specifications for hydraulic fills [Specifiche per la compattazione di riempimenti idraulici]

A common problem with hydraulic fills arises during construction when acceptance criteria are considered. Contractual disputes are mainly related to degree of compaction and they arise largely because of poor specifications. A good specification is one that can be measured unambiguously in the field using reliable equipment. This paper describes the engineering process which should be followed during design and construction of hydraulic fills, starting from conceptual design all the way through to construction and subsequent use of the fill, focusing on the density requirements, specifications and acceptance criteria for density of the fill. It provides a methodology to specify the density of the fill, which will avoid most of the typical pitfalls related to hydraulic fills. This paper takes the CIRIA publication on Hydraulic Fills (Hydraulic Fill Manual for Dredging and Reclamation Works”, van’t Hoff and van der Kolff, 2012) as its starting point developing further considerations to supplement what is given in that document and in doing so tries to establish what is current best-practice.