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A pumping station is expected to be built to ensure Bob Dunn Way does not flood to the levels experienced over Christmas and the New Year.
Council leaders will tomorrow night (Thursday) discuss the issue with plans to install a pumping station 50m east of the Marsh Street roundabout to remove heightened ground water and surface water into the sewer.
The report before councillors states: “Due to the level of the road, even with a pump station in place, flooding is likely continue to be an issue, albeit to a lesser extent.
“To ensure improved management of the situation in future, a flood response plan will be put in place and include considered strategies for communication with residents and key stakeholders and a traffic management plan.”
Groundwater levels recorded by the Environment Agency in Orpington shows levels were nearly twice as high in January as they were in October 2013.
The levels continued to rise throughout November, December and January.
Flooding on the road, part of which is just 50cm above the water table, between the Marsh Street roundabout and the junction of University Way began on the evening of December 23.
The inside lane was immediately closed but by January 3, flooding extended into lane two and the road was closed completely.
Traffic was diverted through the town centre via Burnham Road, Home Gardens and Crossways Boulevard.
The report continues: “Despite assistance from Kent Police and frequent site checks, drivers persistently disregarded the road closure.
“On January 8, concrete rings were placed at the junction with the Marsh Street roundabout. This measure is only ever used as a last resort as it prevents access for all vehicles including emergency services.
“The continuous flow of groundwater made clearing the flood with tankers not feasible. The possibility of pumping the water into Thames Water’s combined sewer had been considered in the past, however, the risk that this would result in sewerage being surcharged had been highlighted and this option deemed unsuitable.”
On January 22 the decision was taken to pump floodwater from the highway into the land to the north of Bob Dunn Way.
Almost immediately, concerns were raised that this would affect protected species know to be living on the site.
An agreement was then reached with Prologis and Persimmons Homes that floodwater could be discharged into a pumping station serving The Bridge development.
Pumping equipment was put in place on January 24 and Bob Dunn Way was reopened to traffic on January 26.
The pumping station failed on January 28 so arrangements were made to pump water directly into the Thames Water sewer.
The drainage system on Bob Dunn Way is inspected, cleaned and tested every six months. Bob Dunn Way was last visited in August 2013 and no defects were identified.