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I I I I I I I I I I I I I I Simons. Li and Associates, Inc. Job. No. 6143J002 Project: Portland Flume Reconstruction elements; battered piles; and mud jacking. Each method has certain advantages and disadvantages depending on loading con- ditions, acccessiblity, time constraints, subsoil conditions and numerous other factors. Temporary support and/or permanent underpinning should be approached on an individual basis for each structure. Contractors experienced in this type of work are a valuable source of information. Therefore, it is recom- mended that the contractor performing this work be required to submit a design for each structure to be reviewed and modified by the engineer prior to installation. In this way, the con- tractor can best take advantage of his equipment, personnel, experience and knowledge which should result in the most economical solution. In general, temporary supports or permanent underpinning systems will be required for any foundations intersecting a line drawn upward at a slope of 1:1 from the bottom of the flume excavation. This can be modified somewhat if relatively rigid lateral support of the excavation walls is provided. Foundations for temporary shoring and/or permanent underpinning systems should be designed to bear below the theoretical 1:1 line with a minimum depth of 4 feet below lowest adjacent fin- ished grade for permanent elements, .nd should be sized based on a maximum allowable bearing capacity of 3000 psf. General comments on individual structures are included hereinafter: I I I I Structure No. SP - (Sta. 11 + 37): It does not appear that this structure will require temporary support. However, due to the relatively heavy foundation loading of this building, it should be monitored closely during construction. It appears that inclined bracing or pit underpinning would be feasible for this structure. I -10-