In Tucson, Arizona, a new engineering design improves the Speedway Boulevard corridor, from Camino de Oeste to Painted Hills Road, from a two-lane road to a modern three-lane urban collector roadway with paved shoulders. Improvements include horizontal and vertical geometry, intersection realignments, traffic control elements, improved drainage conveyance, pedestrian and bicycle facilities, a new bridge over an existing wash, and ADA accessibility.

The new design improves public safety with the elimination of substandard curves and line-of-sight conditions, and the addition of a continuous center turn lane for improved access and reduced traffic congestion, bicycle-accessible paved shoulders, and an ADA-accessible pathway.

Engineering work addressed roadway design, traffic analysis, hydrology and channel hydraulics, geotechnical analysis, pavement design, bridge design and other structural elements, utility relocations, environmental requirements, construction considerations, cost estimating, and scheduling.

The device designed is a mixer-settler that mixes hydrophobic solvent with an aqueous media that contains the metal needing to be extracted. The mixer-settler can separate a large amount of metal from the aqueous mixture in a relatively short amount of time. Calculations were carefully made to scale and optimize the function of the device. A 3D-printed plexiglass model helped with observing the mixing process and making appropriate changes. Testing and analysis improved the device’s capability. Extraction entraining with hydrophobic fluid is expensive. The mixer-settler design uses less hydrophobic fluid and shows a lot of promise for use in the future of mining.

Arizona’s Cave Creek plant was removed from service in November 2009. The plant is now being redesigned to improve efficiency and handle the town’s growing population. For this reopening project, a preliminary design and hydraulic profile were created, design flow rates were determined, recommendations for potential effluent uses were made, and overall economic evaluation of capital and operational costs were completed. Several design alternatives were made initially, and the final design was chosen based on an analysis of population, cost, environmental factors and efficiency. The major changes made to the plant include addition of several screens, a completely updated secondary treatment section and a different disinfection technique. Cost of implementation –including equipment, construction and installation, cost of maintenance, and total cost of electricity to run the plant –were the main factors in the cost analysis. Several recommendations for the treated wastewater effluent were made based on the water quality provided by the plant. This project will optimize the Cave Creek plant and provide a clean alternative method for providing freshwater to Arizona.

The Cave Creek Water Reclamation Plant in Arizona was closed in 2009 because of slow population growth. Current population growth has created an opportunity to reopen the plant. Design improvements will start with water intake at the influent pump station, which passes through a series of screens and through the grit removal station. At the primary clarifier, most of the water will pass through to the aerator, while the rest will go to the sludge holding tank to be dewatered. The water from the sludge will be returned to the influent pump station and sent back through the process, and the dry sludge will be taken to a landfill. After passing through the aerator, a second sludge step will be conducted in which most of the water will pass through sand filters, and the rest will be transferred into the sludge holding tank. From the sand filter, the water will make its way through ultraviolet disinfection. The ultraviolet lamps will include quartz sleeves for reduced maintenance, and low-pressure lamps will be used to reduce energy use and carbon footprint. After disinfection, sodium hypochlorite will be injected to further disinfect the water. The finished product will be stored in the effluent storage tanks and then sent down to the wastewater treatment plant for further treatment.