Worth Farm flood detention reservoir: challenges during construction Available to Purchase

Worth Farm is a new flood detention reservoir on the outskirts of Crawley in West Sussex, which forms part of the Environment Agency's wider Upper Mole flood alleviation scheme. It comprises a 330 m long, 8 m high zoned earthfill dam with a 1ṡ4 m diameter culvert through it and a 140 m long reinforced grass spillway. Construction commenced in February 2012 and was due to be completed within 12 months, but owing to a number of issues encountered during construction, was delayed and final completion is programmed for April 2014 (the preliminary certificate was issued in March 2014). This paper describes some of the issues encountered during construction and how they were resolved. Particular challenges have included carrying out major earthworks during the second wettest year on record, encountering springs, historic landfill and soft ground conditions and ensuring watertight joints when constructing the control structures from precast elements. The author has been involved in various design stages of the dam since 2010 and has been the site supervisor under the Engineering and Construction Contract throughout construction. This paper summarises his experiences and some of the lessons learnt during construction.