No major lock refurbishments were planned for 2010 on the Chelmer & Blackwater Navigation. The major Essex Waterways Ltd project for the year was bank piling at Paper Mill Lock. This had to be undertaken during the summer when the risk of flood conditions was (hopefully) at its lowest. The poor condition of the lower bank between the two weirs was quite evident when seen from the mill pool below the lock. Here the plastic and timber piles were obviously failing with the risk of further bank collapse. If left unchecked, this would result in failure of the weir structures which are especially prone to heavy flood flows.
Less obvious was the weak condition of the upper bank adjoining the weirs at Treasure Island, as this is on the backwater. Erosion here had reduced both the bank height and bulk and during last winter's flooding the bank was close to a breach situation. This would have had dire consequences upon the moored boats at Paper Mill and therefore repairs needed to be implemented.
While piling schemes for these two banks were being evolved, the island bank below the lock began to show signs of collapse with sections falling away. Once the adjoining piling work was underway, the deterioration of the island bank became more rapid and the decision was taken to re-pile this whilst the contractor was on-site.
One of the prime difficulties with such work on the Navigation is the lack of land access and thus the need to bring in specialist floating equipment. This obviously comes at a cost, although use of plant specifically suited to the work can of course be cost effective. In this instance Land & Water were appointed as specialist contractors, having considerable experience of this type of work.
“Mobilisation”, that is bringing the plant and equipment to site and setting this up, was an impressive operation. This involved a convoy of large HGVs being brought to site one at a time, in a pre-arranged order so as the equipment they carried was that needed for the current assembly operation. The person responsible for this part of the contract was Mick Beattie, long-serving volunteer with Waterway Recovery Group, as well as his day job with contractors Land and Water.
The work between the weirs and to the lock island required the use of 7 metre long piles with a cost of over £35,000 for these piles. The piling rig was placed on a large pontoon which was assembled from twelve sections which were transported on two large articulated vehicles.
Backfilling of the newly piled areas was from gravel gained by dredging out a shoal from the mill pool, thus removing an obstacle to navigation whilst also being a very sustainable operation. The excavator used for this was placed in a wide beam purpose made barge that was delivered in two sections, so as to be road transportable, and assembled once placed in the river. The smaller section piles to the upper bank were installed with this equipment.
A motorised tug was available to assist with the operations.
Essex Waterways Ltd has been particularly successful over the last five years in obtaining grant funding towards the four major lock restorations on the Navigation. In the current financial climate it is much more difficult to achieve funding assistance, and it seems that works to pile banks, however necessary, are perhaps less glamorous than refurbishing listed lock structures! We were therefore especially pleased to receive a grant of £10,000 from Essex Environment Trust (courtesy of Essex landfill operators namely Lafarge Aggregates Ltd., Cory Environmental Ltd. and Veolia Environmental Services) towards these works.
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