USA Prairie Waters Project

Siemens Water Technologies (USA) has received a 1.95 million euros ($2.9M) award to supply equipment for the new 189-MLD (50-MGD) Aurora Reservoir Water Treatment Plant, which is part of the Prairie Waters
Project for the City of Aurora, Colorado, USA. Water from the South Platte River will be piped 54 km (34 miles) to the water purification plant, where it will undergo softening, filtration, ultraviolet light oxidation and activated carbon adsorption before being distributed. The softening equipment supplied by Siemens includes four 47-MLD (12.5-MGD) Contrafast high rate sludge thickening clarifiers for installation in
concrete basins. Siemens will also supply 70 ESSD stainless steel washtroughs for placement in media filters and activated carbon adsorption cells. The project will provide a sustainable supply of high quality water to meet the City’s demands into the 2020’s. Both of the
City’s existing water treatment plants received the Phase 3, Director Award from the American Water Works Association (AWWA) Partnership for Safe Water, and the new plant is designed to continue to meet this
commitment to water quality. The first phase of the new plant is scheduled for startup in 2010.
The City’s design consultant, CH2MHill, conducted a pilot test of softening and filtration systems. The results of these tests showed that Siemens’ equipment met the City’s standards for water quality, ease of operation and reliability. Chemically dosed raw water is mixed with previously formed solids inside the concrete basins and an external sludge recirculation. The first stage of the Contrafast units incorporates a specially designed mixer within a reaction chamber to shear and reform precipitated solids, which increases the sludge particle density. This decreases the required settling area and
reduces the amount of sludge produced. The second stage of the units provides additional thickening and clarification of the water prior to filtration.
The ESSD washtroughs will be constructed entirely of 316 stainless steel for corrosion resistance and durability. Washtroughs for the media filters will incorporate factory installed Multiwash media retaining baffles to retain the filter media during combined air
and water backwashing while water overflows the washtroughs. This backwash cycle provides the most efficient cleaning of the filter media.