Electrical shutdowns caused a pumping station in Sao Paulo, Brazil to fail and when they happened at night, engineers could not visit the site as it was too dangerous. That left 240,000 people without water until the next day. But using WaterCAD, water company Sabesp was able to develop a solution that not only provided continuous water supply to the inhabitants, but also saved BRL 700,000 in energy costs.
As one of the largest water and sewage services providers in the world, Sabesp MA has a huge responsibility to provide clean drinking water to 27.7 million people. Jardim da Conquista is one of its major pump stations bringing water from the Rio Claro aqueduct through an 800 mm pipe supplying the Jardim São Pedro tank with an average flow of 388 lps.
This pump station suffered electrical shutdowns due to failures in the supply of the power utility. Each time this occurred, staff had to be onsite to restart the pumps and electrical panels of the pump station and when this happened at night, it was unsafe to send Sabesp personnel there because of its proximity to dangerous areas.
Sabesp engineers initially considered disabling the Jardim da Conquista pump station, and transferring all pumping to the Vila Bela pump station, which would directly supply the Jardim São Pedro tank and as a result, supply the Jardim da Conquista tank.
Hydraulic modelling
However, to better understand the operation of the entire system, Sabesp first performed hydraulic modelling of the system using WaterCAD. This enabled them to develop an alternative supply strategy. They found that by constructing a 17,696 m3 oversized water tank at Jardim São Pedro, if the pumps shutdown in the evening the tank would have enough water to last until the next morning.
WaterCAD helped determine the operating conditions of the existing pumps and if they were working within operating range. Sabesp hydraulic modelers were then able to test the setup of new pumps that would best comply with a flow rate of 390 lps in regular operating conditions, as well as a flow rate of 800 lps in the case of night time pump shutdown, so the water tank could continue supply for up to 12 hours.
With WaterCAD, engineers were also able to find out how long the pumps would need to fill up the new tank before nightfall, in preparation for possible evening power outages. With this hydraulic modelling work, Sabesp reduced the time it would have taken for the Jardim São Pedro tank to reach its increased volume of 17,696 m3, from seven days and three hours to an average of 16 hours, increasing the water supply system reliability.
To achieve this, the other tank, Jardim da Conquista, was also replaced, with doubled capacity from 4,347 cum3 to 8,694 m3, increasing operational security. With the new pump station configuration, WaterCAD solved a recirculation problem with the existing pumps, allowing a better use of Jardim da Conquista tank upstream of the Jardim da Conquista pump station.
Financial and community improvements
Using WaterCAD, Sabesp was able to select the optimal pumps for the Jardim da Conquista pump station, thereby increasing water supply reliability, providing inhabitants with continuous water supply and improving their quality of life. Shutting off the Jardim da Conquista pumps during peak hours also reduced the electricity costs. Sabesp’s initial solution of closing the Jardim da Conquista pump station and transferring all pumping to the Vila Bela pump station would have cost around BRL 400,000 per year. But using WaterCAD’s scenario management, Sabesp was in fact able to cut its electricity costs by BRL 700.
“Using WaterCAD, we were able to analyze and compare different solutions to the pump shutdown problem,” said André Luiz de Freitas, engineer at Sabesp MA. The optimal solution offers a combination of advantages, from uninterrupted water supply to large operation cost savings. With a total project cost of BRL 20,000 increasing the volume of the Jardim São Pedro tank enabled Sabesp to achieve a 54-times return on investment in the first year.
