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81 I. S. S. GREEVES M r A. W. Shilston. Consulting Engineer This is a scheme which provides an admirable subject for case history study.104. It is conventional in an industrial type project that the desired process plant layout arrangements largely determine the building structure form. The impression created by this Paper is that substructure design/construction considerations dictated the layout of this substantial sewage-handling installation. Such approach would not appear to have produced any problems in building superstructure design. All that has to be asked then, on the broad conceptual aspect, is whether it can be assumed that the resulting (unusual) plant layout imposed by overall capital cost considerations has caused no disquiet to those responsible for operation and maintenance.105. Overall design, construction, plant installation and commissioning being so interlocked, have the Authors any views on how a repeat scheme might be orchestrated with increased facility through changed contractual arrangement& assuming that the listed subcontractors were nominated by the Employer to the main civil engineering contractor and conventional standard form contract conditions prevailed, generally. Behind that question perhaps could be kept in mind that the Paper is silent on how the activities, on site, of the principal mechanical and electrical contractors were co-ordinated.106. On more detailed points, mindful that the pumps were selected to be capable of passing a 100 mm sphere (9; 18), what was the bar spacing of the mechanically swept protecting screens?107. Regarding the ground conditions (g 32-35), were the results of the ten-day pumping tests conveyed to tendering contractors and was the revealed subsoil water pattern susceptible to seasonal influences? 108. On substructure design, in evaluating steel-sheet-piled circular cofferdam construction versus diaphragm wall construction, it no doubt was intended that the permanent construction would be built independently of the steel sheet piling, but was it contemplated in the appraisal that the entirety of the piling would be extracted successfully with a saleable value on disposal as second-hand piling?109. 5 58 indicates that it was intended that the finish of the outer (diaphragm) wall of the wet well would be that left by the trench excavation cutting tool.