A trial trenched evaluation (37 trenches in total) was carried out by Colchester Archaeological Trust in advance of the construction of a farm biogas digester plant and lagoon (CBC planning application 150391). <1> At the time of the evaluation, the site was open ground (some grassed and used for vehicle storage) and the remainder was under arable cultivation. Twenty-one trenches (T1-T21) on the site of the proposed biomass facility (Area A), and six trenches (T22-T27) on the site of a new agricultural lagoon (Area B). The evaluation trenches were excavated under archaeological supervision using a tracked excavator, through two layers. A modern topsoil 250-400mm thick (L1), and a silty clay accumulation horizon (L2) 250-300mm thick. Nine archaeological features were revealed by the evaluation: modern pits and ditches, and areas of disturbance associated with the construction and subsequent demolition of the airfield. There were also three undated 'natural' features. A desk-based assessment was compiled by Archaeological Solutions in June 2015. <2>