The multi-million pound scheme will help to “significantly” improve the water quality of the river.
Yorkshire Water is spending £16m on the new facility to replace the current works, which is over 100 years old and struggling to cope with the increased flows coming into it as a result of local population growth and climate change.
The new treatment works will be able to treat waste water more efficiently, and to a higher standard, before discharging it into the adjacent River Aire.
Yorkshire Water said that the new treatment process will lead to lower levels of ammonia within the treated water, which should help to ensure that fish life in the area of the Aire immediately downstream of the works can thrive, and hopefully encourage species such as salmon and trout, which have not been seen in some sections of the Aire for over half a century, to return.
Some of the features of the new works include a series of filters to remove debris, such as nappies, sanitary products and baby wipes from the waste water before it is treated.
The new plant will be built on the site of the ageing current facility, which will be decommissioned once the new plant is up and running.
The project is expected to be completed by March 2015.
Matt Thompson, of Yorkshire Water, said: “The current facility has served us well for over 100 years, treating Castleford’s waste water before discharging it into the Aire.
“However, as Castleford’s population continues to grow, with forecasts predicting it will be at 57,000 by 2025, and storm events become more common, it’s vital that we create this new plant to meet the changing local needs. Not only will it be more compact, but it will be able to treat more waste water, more efficiently and to a higher standard, boosting the quality of the Aire and helping riverlife to thrive.”
The new plant, which has been the target of metal theft attacks in the past, will also benefit from 24 hour security and surveillance. Engineering experts Morgan Sindall Grontmij JV will be working on the project.