A number of significant positive and negative economic impacts could result from Pima County's SDCP and related programs, according to an analysis of existing research on large-scale conservation planning undertaken to provide a framework for community decision-making. This report offers no final verdict on the net economic impact of Pima County's current, ambitious initiatives in habitat conservation and growth management. However, it does provide a framework for future assessment and decision-making.

This report provides a simplified method to be used for evaluating the skin friction and tip resistance of axially loaded drilled shafts. A summary of literature and current practice was completed and then a comprehensive set of field and laboratory tests was performed. Several soil samples were collected from different sites from Arizona and surrounding states. Large scale direct shear apparatus was developed and used to determine the friction between soil and concrete. Finite element analyses were conducted on several prototype cases to determine effect of soil parameters such as dilation on the skin friction values. A step-by-step simplified approach was introduced to determine the skin and tip resistance of drilled shaft foundations in gravelly soils. An example application was presented to guide users in utilizing the simplified approach.