There's a whole host of major work and planning behind the scenes going on at the reserve presently soaking up most of Amy and I's time; Hence big thanks to Margaret for keeping the blog updates going this summer. In due course we'll be able to reveal all the works around the plastic newt fencing etc but in the here and now, the current undertaking is the 'Thrust Bore' under the river Hull.
This work has been undertaken as surveys revealed structural issues with one of the two 1950's water mains. This could be due to the scour of the river Hull during winter flood events over the last couple of years. As such it was decided new mains should be installed as a priority before any further deterioration.
The operation involves sinking two 8m / 30ft diameter shafts around 40ft below the river Hull on each bank. The launch and main operation was from the east bank at Baswick;
And passed to our west bank at South Lagoon. This was somewhat tricky as the reception pit started out as a marsh which had to be checked and signed off by ecologists before being prepared;
Excavation of the shaft unearthed this huge lump of bog oak - anaerobically preserved and thousands of years old (Another example on site is the bough in front of Izzard hide - we intend to use this for similar purposes);
Here's the completed shaft from above:
The machine used was a 'Thrust Bore'; Essentially same as the channel tunnel; The milling head rotates and chews its way through, with aqueous silt discharged into dedicated settlement lagoons:
Behind it are fed 1.2m diameter concrete pipes one at a time;
As each pipe is added a hydraulic ram shunts the hole train fowards before returning for the next one:
Precision guidance means that it emerges at the exit perfectly:
As the machine enters the pit the shaft needs to be flooded to equalise pressure with divers sent in to tighten a gland around the emerged pipeline.
So currently the job has gone very well with both pipelines laid.
Big thanks to everyone at Tophill Low for their patience with this work thus far and we are aware of the inconvenience for people having to walk an extra distance on grass to reach such as Izzard hide. We have been made aware of a minority of individuals ignoring the signage etc which is disappointing and creates a hazard so please adhere to all signage as we may have to review membership privileges for repeat offenders.
However we are aware that we are coming into winter with muddier paths and at least this significant phase of work is complete, so we've worked with Ward and Burke to ensure we can deliver a safe pedestrian access that cuts down the need for walking around one side only. So as of this weekend a safe pedestrian walkway will be provided around the perimeter of the compound under the 'O res viewing screen'.
There will still be no access via the lagoons with the footpath remaining closed at North Lagoon and strictly no access into the work compound at the O reservoir main gate. All O reservoir access will continue to be via O reservoir woods bridge and the access road for the foreseeable future - likely into the new year; As before combination code available at the reception hide.
Further details to follow on additional works and route closures for other projects will follow shortly.
