In January 2002 HR Wallingford published the results of work undertaken on behalf of P&O Ports Limited and the Port of London Authority to investigate the effects of dispersion of fine material arising from dredging and reclamation activities associated with the proposed London Gateway Port (Reference 1). Further plume modelling results, produced for P&O Ports Limited, were published in March 2003 (References 2 and 3). As an aid to understanding the sensitivity of the plume model used for these studies a series of sensitivity tests were undertaken. These sensitivity analysis tests have not been previously published and a selection of test results are presented in this report to provide additional confidence in the results published in References 1, 2 and 3.