Thornham Farms - Irrigation Reservoir

January 2007 saw the commencement of the excavation of the third lined reservoir for Thornham Farms (Norfolk) Ltd. Once constructed the reservoir was capable of storing up to 50.60 million gallons (230,000 cubic metres) of water for irrigation purposes. As in excess of 5.5 million gallons of water was to be stored above ground level, the design and construction methods had to be approved by a recognised Panel Engineer prior to commencement on site. The reservoir was designed by Prime Irrigation Ltd; the Earthworks Contractor was W R Chapman and Son.

The reservoir was constructed using a classic 'cut & fill' method whereby the site was stripped of topsoil and the underlying materials excavated and used to form embankments above ground level. The predominant material was chalk; a good material with which to create a sturdy reservoir structure. The embankment materials were placed in compacted layers - which is standard practice - to ensure their long-term stability.

The reservoir required the installation of approximately 40,000 square metres of lining system. Exceliner LLD 1.00mm was installed over a 500g per square metre (6200N) Geotextile underlay. Both products carry a 20-year warranty and have a working life in excess of 50 years.

Lined Area: 40,000 square metres

Materials Used: Exceliner LLD 1.00mm / 6200N Geotextile underlay

Designer: Prime Irrigation Ltd, Saxmundham, Suffolk

Earthworks Contractor: W R Chapman & Son, Kings Lynn, Norfolk