Marden Quarry Park Drainage - Update - 27, February 2020

Update 4 March, 2020

This update about the drainage of the lake in Marden Quarry follows the clearance of the blockage attributed to tree roots within the pipe that runs from chamber 3 of the lake outlet to the Northumbrian Water Limited (NWL) sewer that carries water to the North Sea. The lake outlet comprises two lakeside chambers, 1 and 2 connected to chamber 3 by separate pipes. Both these pipes were thought to be blocked but on investigation by a specialist contractor engaged by North Tyneside Council (NTC) the blockage was discovered to be tree roots in the single pipe that connects to the NWL sewer.

More details about this history during last year is given in the updates on this page for the period from March to October, 2019.

The video below has been created from photographs and a few short video sequences recorded following the removal of the tree roots that was carried out by the same contractor on 30 August, 2019. The “dry weather pipe” (a term used by NWL) that runs from the back of chamber 1 has an intermittent blockage caused by an air lock. This was  discovered in 2019 during clearances of the blockages of the wire mesh that covers part of the chamber 1 outlet grille. The air lock is created when the water level on the inside of the grille falls to a level such as to allow air into the pipe.

The 4 extracts from messages below are a brief record of those related to the poor drainage from the lake.

In a response from NTC to the formal complaint, dated 1 June, 2016:-

"There have been difficulties with the operation of the sluice gate in recent years culminating in the mechanism becoming fully jammed. It is clear that the sluice gate has reached the end of its serviceable life. Work was undertaken in Autumn 2015 to partially free the mechanism as a temporary solution. As part of the Burnside Road Flood Relief Scheme the intentions are to replace the structure with one that is new and more fit for purpose. This work will be undertaken in June/July 2016. This update addresses Recommendation 3 in my response of 1 February where I suggested that an update on the future of the sluice gate be provided.”

In a further response from NTC to the formal complaint, dated 1 November, 2016:-

"The Council has been working closely with Northumbrian Water as they have  undertaken their considerable investment in upgrading the sewerage system serving North Cullercoats. As part of our partnership working, consultants commissioned by Northumbrian Water have provided the Council with a repair solution. This involves replacement of the outfall structure. Construction of this is now in the process of being procured via the Council’s asset management team.”

In an email from NTC dated 18/01/2018 in response to a enquiry raised via a ward councillor:-

"The work was undertaken as a planning condition on the Fairfield/Briarvale Surface Water Management Scheme. The works involved clearing out the chamber sumps / refurbishing the pen stock and cleaning the fixed weir. In answer to Mr Smiths enquiry the fixed weir is the main chamber outflow and the pen stock (emergency overflow) has been set at a level to ensure that it acts as such and will be monitored and raised/lowered to manage the level of the pond as required. This pond is due to be inspected at the end of the month and any necessary adjustments to the position of the pen stock will be made during that visit.”

In an email exchange about the same planning condition # within NTC, dated 17/04/2019:-

"The works involved the jetting and clearing of the pond outfall pipe, the refurbishment of the adjustable penstock weir – to allow seasonable/weather event adjustment of water level and the replacement of the sealed chamber cover with a mesh grille to allow water to discharge should the inlet become blocked and be overburdened.”

On discovery of the document dated 17/04/2019 this document was sent to the NTC Planning Manager about the failure of NTC to formally discharge any of the planning conditions for the Briar Vale flood prevention scheme before the work was completed.

 # Prior to the discharge of any surface water from the dry storage basin to the NWL sewer network, full details of the improvement of the outfall within Marden Quarry must be submitted to and approved in writing by the Local Planning Authority. Thereafter, the development shall be carried out in full accordance with the approved details.

The video shows that despite the clearance of tree roots in the main outlet pipe the flooding of the lake boundary still takes place due to blockage of the wire mesh. In December 2019 there was little floating debris and it was occasionally cleared. From the end of December there was none during the following several weeks.

The sluice gate is still jammed in the setting left in the Autumn of 2017 by contractors working for North Tyneside Council . The "dry weather pipe", misleadingly referred to as a "fixed weir", gets blocked by a re-occurring air lock so does not work as described.

Update 4 March, 2020

On the morning of Monday, 2 March, 2020 the penstock weir gate (sluice gate) was removed, leaving the fixed part of the structure in place. During the next 48 hours until the morning of Wednesday, 4 March the lake water level was photographed and monitored. The values given are relative to the invert of the notch in the wall of chamber one. The values recorded were 10cm at start (1102, on 2 March), 5cm (1045, 3 March), 3cm (1511, 3 March), and 2cm (1026 4 March).

It was noted that the top of fixed sluice gate structure over which the water flows into the second chamber is about the same level as the invert of the notch. There was no apparent flow into the "dry weather pipe" but it would have been small, if any, in comparison with that into chamber 2.

The video below is a record over the 2 days.