This is one a a series of articles published in Longstanton Life between February 2016 and the present, showing just how often dire warnings were issued about the destruction of Longstanton’s groundwater, and just how often they were ignored by those whose duty it was to take timely action.
Hilary Stroude wrote:
Kingfisher Pond – HR Wallingford Report 3
LDHS members and local residents will be aware of the constitutional obligation that the Heritage Society has to protect heritage assets across Longstanton, Northstowe, Oakington and Westwick and that landscape features are included in our definition of Heritage. Hence, for many years the Longstanton & District Heritage Society has been highlighting the plight of the Kingfisher Pond and other ponds and water features located on the River Terrace Deposits (RTD), which lie below our communities.
The purpose of HR Wallingford’s final report was to determine the cause of the changes in the hydrology and hydrogeology of the Kingfisher Pond. Their report is clear in its key finding that it was the initial construction dewatering that led to the drying out of the Kingfisher Pond. Why then was no enforcement action taken by SCDC when local residents first raised concerns at the end of 2015, after the first phase of de-watering was carried out? If action had been taken when concerns were first raised, the second phase of de-watering could have been stopped and the cause of the problem identified and rectified. This report cannot be clearer – it states that the construction of Northstowe has changed the recharge of the RTD and the ponds and other ground-fed features. This is simply unacceptable and someone should be held responsible; not just for what happened but also for the failure to take action when the problem was first reported. Furthermore, the report makes clear that the damage caused might not be repairable and water levels may not recover to pre-Northstowe levels.
However, what is of really serious concern is the questionmark the report raises as to whether the design principles of the greenways have been met, or if they will continue to reduce groundwater levels in the RTD and the Kingfisher Pond. Failure to act on residents’ concerns in a timely manner has potentially allowed those greenways to be completed with any errors or changes to the design principles buried below ground.
However, this is where the remit limitations of HR Wallingford’s brief are exposed. Despite all the evidence and the confident conclusion that dewatering of Northstowe caused the damage to the Kingfisher Pond and by implication the other ponds and groundwater features, the report appears to have only recommended that monitoring is installed and maintained to determine the impacts of the Northstowe ground-works on the Kingfisher Pond and other ground-fed water features. Whilst monitoring of the RTD is welcome and should have been in place from the start of work out on Phase 1, there is no mention of what action must be taken to repair the damage to the aquifer and to ensure that the groundwater levels in the RTD do recover to pre- Northstowe levels.
In addition, other more recent and on-going issues exist which have not been dealt with by this report. The HR Wallingford final report fails to acknowledge or explain how and why the Phase 1 lake could fill with water by 2017, whilst at the same time the Kingfisher Pond stood empty. Also not explained by this report is the reason for water being pumped off Northstowe Phase 1 in significant quantities, over extended periods of time. This discharge of water was reported to local councillors, HR Wallingford and others late in 2020. Also reported was the apparent cessation of water being discharged off site early in 2021, despite high levels or rainfall and water being pumped off Phase 2. There was no explanation for this either.
HR Wallingford have stated that they would be available to carry out further work under a new contract and hopefully this will be carried out with the remit being what restoration work and mitigation can repair the damage caused by the Phase 1 de-watering of the RTD aquifer. However, what is clear is that whilst the H R Wallingford investigations and reports 1-3 are welcome, serious questions remain to be answered . Whilst SCDC has published a plan of action, further investigations are needed to provide answers and for confidence to be restored in the drainage works associated with the Northstowe development.
In recent weeks, a planning application has been submitted for the modification of swales in the northern greenway out on Phase 1. I have submitted an objection to this planning application, because there should be no changes to the drainage system out on site until the issue of the groundwater problem is fully understood once and for all. If the design or construction of the Phase 1 drainage system has contributed to the groundwater problem then modifying it now, prior to further investigations, could prevent the village getting to the bottom of what caused the environmental problems we have seen in recent years.