New wastewater plant in five-year plan to turn sewage into irrigation

Farmers could soon see a major drop in irrigation expenses, as the government finalises plans to set prices for treated wastewater from the new Climate Resilient South Coast Water Reclamation Project — a five-year undertaking designed to reuse sewage for agricultural use and bolster the island’s climate resilience.

Barbados Water Authority Chief Executive Officer Christopher Mapp said the current rate paid by farmers had already been reduced in recent years and could change again once the new system is operational. But he stressed that that decision would be at a governmental level and not the island’s sole water utility entity.  

“That is the current rate that came out about two years ago. It was actually reduced to $1.80 … and then it reduced to $1.00. It could change but that’s a government decision. Nothing to do with the Barbados Water Authority. The government will determine the rate for this reclaimed water,” he told Barbados TODAY late Thursday following the launch of the state-of-the-art project at Harmony Hall, Christ Church.  

BWA Technical Adviser Dr John Mwansa outlined how treated wastewater would be supplied to farmers through irrigation systems managed by the Barbados Agricultural Development and Marketing Corporation (BADMC).  

Dr Mwansa said farmers would not have immediate access to the reclaimed water, as construction of the new treatment plant is expected to take approximately five years.  

“The first thing is that the plant will take five years to build,” he said, adding that the project includes several components beyond the new facility itself. “The project has several components. The first major component is the construction of this plant. In addition to that, they are going to rehabilitate the old plant, because we still have to screen the sewage when it comes in.”  

Dr Mwansa explained that sewage would first be screened to remove solid debris before being pumped to the new plant, which is being constructed on higher ground than the existing facility as a climate-resilience measure.  

“After the sewage is screened, you take out the pebbles, the rocks. It will then go into a new lift station to pump the water to this site here, because this site is four metres higher than the existing plant,” he said. “With climate change and the potential for storm surges, you want to elevate your plant.”  

He said the wastewater would then undergo a series of advanced treatment processes to ensure it meets strict agricultural standards. “It will go through a biological treatment process first, and then it will go through some filters to remove any remaining particles, and then it will be pushed through a reverse osmosis plant,” Dr Mwansa said, noting that the membranes used are similar to those at the Spring Garden desalination facility.  

According to Dr Mwansa, reverse osmosis was included to meet the Ministry of Agriculture’s requirement for irrigation water quality. “The Ministry of Agriculture wanted the water that comes out and goes to the farmers to have a total dissolved solid of 450 milligrammes per litre,” he said. “If you have more than that, it will clog up the soil that you are irrigating.”  

He added that the treated water would be disinfected using ultraviolet light and chlorination to protect a 25-kilometre transmission pipeline running along the ABC Highway, past Deighton Griffith Secondary School, through Bannatyne, and into the St George Valley to River Plantation. “The purpose of the chlorine that will be added is to ensure that that doesn’t happen,” he said, referring to the risk of mould regrowth in the pipeline.  

At River Plantation, the reclaimed water will be received by the BADMC at Brown’s Pond and distributed to farmers connected to the irrigation network. Dr Mwansa said excess supplies during the rainy season would be used to recharge the aquifer through five injection wells. “Remember, during the rainy season, they will not require water for irrigation. So where does that water go? We use it to recharge the aquifer,” he said.  

He also revealed that two new boreholes would be drilled at Gibbons Boggs, Christ Church, to allow farmers to access water drawn from the recharged aquifer, while a branch of the pipeline would extend beyond Deighton Griffith Secondary School to Coverley.  

Dr Mwansa said the South Coast initiative would be complemented by upgrades to the Bridgetown Sewage Treatment Plant, with reclaimed water from that facility to be pumped towards the Botanical Gardens and stored at Lears Pond for distribution by the BADMC. 

“That will supplement that storage because the capacity of that during the dry season may only meet half of the capacity of the farmers that require water in that area,” he said. “So the water that will go from here will supplement the irrigation requirements.”