Discussion. Extensions to the Riverside Sewage Treatment Works. (Includes Corrigendum).

Abstract

I would like to pay tribute to the many individuals and organizations to whom we are indebted for co-operation and assistance in bringing this scheme to fruition and to acknowledge the help of our Architect and .our assistants in the office and the site supervisory staff.74. We have also had sympathetic help from the Port of London Authority who have appreciated the difficult problem posed by the nature of the trade effluent in Dagenham. Mr P. A. BanksThe pilot scale trials of secondary treatment of trade waste mentioned in 0 11 have now been completed. With the agreement of the Port of London Authority these trials have been conducted using a section of the full-scale domestic secondary treatment plant.76. The object of the trials was twofold: first, to confirm the practicability of treating trade waste alone, i.e. without mixing it with the domestic settled sewage; and secondly, to find the minimum aeration period that could safely be used. Both these objectives have been achieved.77. The plant was started on a mixture of trade and settled sewage, and in the course of eleven weeks the proportion of trade waste feed was increased to 100%. For eight weeks, whilst the retention period was kept at 12 h or more, satisfactory results were achieved, i.e. the BOD was around 20 p.p.m. under steady conditions. For the remaining weeks of the six month experiment the retention was reduced progressively to 8 h and the BOD figure worsened markedly. During the experiment there was no reduction of ammoniacal nitrogen when running at 100% trade waste. M r J. Perks, Hadsphaltic Construction Co. LtdMy contribution to this discussion is restricted to the construction section generally, and in particular to Contract Cl. The Authors within the text of their Paper have made reference to various management and construction techniques and I feel that it would be of general interest if some were more fully described. 79.In 8 51, the Authors refer to programming and to the use by the Cl Contractor of network techniques, both manual and computer assisted. A major network for the Contract was prepared manually but the resulting programme proved to some extent to be unsatisfactory, inasmuch as structures bearing high float, despite resource restraints, were difficult to position. Upon the major critical structures it became evident that the most effective control could be maintained by restricting detailed programming to construction periods of three months, and it was on these that computer assistance was used. The most successful use of this technique was upon the power wing, where a saving in construction time was directly attributable to the control that the Contractor was able to exercise. 80.In 0 56, dealing with the main power and pumping station, the Authors mention that the cofferdam frames created difficulties in shuttering, and Figs 15 and 17 illustrate this point.That this method of construction was necessary was clearly indicated by the Engineer in his tender documents, but I submit that the opportunity