Gloucester: Dredging the Haul Route

The first workfront needs a usable route

Gloucester's recovery dredge has encountered a constraint on moving the material it removes. Canal & River Trust says reduced channel depths prevented the first team from advancing as close to the Docks as intended. The team instead began just north of Romans Quay, where there was enough water for tugs and hopper barges to carry the sediment south towards Parkend. ^[2]

The charity's October account reports about 120-130 metres dredged and approximately 1,500 cubic metres removed in 11 hopper loads at that location. Its 16 October update records mobilisation from 4 October and a week spent preparing the equipment. The wider programme has a budget of approximately GBP 4 million and a planning allowance of up to about 40,000 cubic metres. The initial haul-route constraint helps explain why those programme totals need a workfront sequence before they can become an output forecast. [1-2]

Available depth constrains the transport cycle

The current method is backhoe dredging from a floating pontoon, loading hopper barges for transport down the canal. The productive cycle includes excavation, barge exchange, loaded passage, unloading and return. A section deep enough for an empty craft may still restrict the same vessel carrying sediment. The route must therefore be checked for the working load and operating water level as well as the dredging pontoon's access.

At Gloucester, the owner says the first available location combined a dredging workfront with enough depth to keep the disposal route functioning. The programme can develop that route towards the Docks as excavation restores access. The team can release its next advance against surveyed clearance, the working loading limit and the next passing or turning location. Booking more excavation plant has less value when loaded barges still have to wait for a constrained reach or unloading point.

Parkend and the lorry route need separate handling plans

The owner has prepared a lagoon at Parkend for material delivered by hopper barge, followed by spreading on agricultural land. The owner is also preparing a lorry collection point closer to Gloucester for material taken to recycling sites. ^[2]

Each route needs its own capacity account. The barge route depends on loaded passage, unloading and available lagoon capacity. The lorry route needs an unloading interface, temporary storage, suitable vehicle access and an available receiving site. Where material changes route, the programme should record the reason and the quantities transferred so that haulage demand and receiving capacity stay aligned with excavation.

Those activities also belong in the cost account. The GBP 4 million is the owner's programme budget. A measured excavation rate on its own would leave mobilisation, waterborne transport, land handling, surveys and operating restrictions outside the comparison. Reviewing performance by complete load cycle would show whether the next improvement should be another excavation shift, an additional barge, a different loading level or more capacity at the receiving end.

The budget history also needs its phase boundaries. In May, the Trust reported 37,000 tonnes removed over the preceding six months and a further 18,000-tonne target, with an estimated total cost of about GBP 4.5 million at that point. Its 28 September announcement then doubled the planned investment in the new programme from GBP 2 million to GBP 4 million. The current 40,000-cubic-metre planning quantity belongs to the later recovery scope. A cost comparison needs the corresponding work period, unit and handling route for each figure. [2-4]

Water supply keeps the sediment balance active

The Trust attributes the accumulation to silt entering with River Severn water pumped into the Docks and canal during the dry summers of 2025 and 2026. The canal supports navigation, shipping at Sharpness and water transfer for Bristol Water. Its water-supply duty continues while the recovery dredge removes deposited material. [1-2]

Bristol Water's 26 August drought account explains that, in dry periods, more than half its supply comes from river sources, including the Severn via the Gloucester & Sharpness Canal. That account gives the water-supply operator's reason for maintaining river inputs while managing reservoir levels. Adjusting pump times to reduce sediment intake has to work within those supply requirements and the available storage and transfer capacity. ^[5]

That makes sediment intake part of the recovery plan. The Trust is working with Bristol Water on pumping times and its own pumping strategy to reduce entrainment. Progress can be tracked through pump operation, estimated incoming sediment and repeat hydrographic surveys, alongside recorded removal. This separates the effect of dredging from new accumulation and from changes in the operating water level.

The owner is also preparing a Habitats Regulations Assessment for possible cutter suction dredging in a future campaign. The current backhoe-and-barge operation remains the basis for assessing today's access and transport constraints. Reopening decisions depend on the restored route and usable depths achieved across it. ^[2]