Overview of Project
The project involved the creation of new mooring facilities for 10 craft, located on the offside of the Limehouse Cut, east of Bridge 4 (Bow Common Lane Bridge), accessed via Hawgood Street, off Bow Common Lane, London.
This section of the canal is fronted by a mixture of contemporary and old warehouse buildings which front the north and south side of the cut. These buildings accommodate a mixture of uses including residential and storage/light industrial. A tow path runs east to west along the south side of the Limehouse Cut.
Existing services are utilised to allow safe treatment/disposal of grey waste with electricity and water being supplied to the new mooring facility. Other facilities include low level lighting, electricity and wifi.
Client Brief
Bluetech was appointed to manage the project once preliminary planning permission was granted for the scheme. Bluetech’s remit included coordinating the design of the moorings, bridgehead, and gangway, together with the necessary services and supporting infrastructure.
We were responsible for satisfying the technical requirements of the Canal & River Trust, together with other stakeholders such as the Environment Agency and Tower Hamlets Council.
Bluetech was also responsible for tendering the works, tender appraisal and the letting of the works. We also monitored the works on behalf of the Client, including dispute resolution and the management of costs.
Environmental Considerations
Biodiversity
The Rivers & Standing Water Action Plan sets out further guidance for reversing the decline in vegetation along large stretches of the canal. The plan recommends the use of suspended gabions and floating islands which can help increase biodiversity both above and below the water line.
A series of gabion baskets have been installed between the moorings and to provide a platform and anchor for the development of reed beds. These will provide an excellent habitat for a diversity of species, including fish, offering them protection from predation. The vibrant and colourful reeds will shoot roots into the water to provide new habitat for insects such as dragonfly and damselflies, as well as feeding and spawning areas for fish, helping to increase the biodiversity of the waterway. The reed beds will also break up the massing of the pontoon and will provide visual amenity to canal residents and visitors.
Once the reed beds have matured these will mitigate any waves caused by passing boats which can bounce back off the walls and can overturn or flood nearby bird nests. This will encourage coots, moorhen, ducks and other waterfowl to nest safely.
Technical Challenges
Varying water levels
At each River Thames high tide, bar some neap tides, the impounded water level in Limehouse Cut increases quickly, until the tide has turned, and the stored water starts to weir off. This is referred to as the “tidal bulge” and during normal conditions typically builds up 50-120mm over a duration of 1 to 3 hours. Following rain events, the tidal bulge may be considerably more. The duration of tidal bulge is dependent on the tide height. As such, the moorings must be designed to accommodate varying water levels, whilst maintaining safe access/egress to the moorings, together with all services.
The works involved constructing a bridge head, together with a ramp to provide safe access/egress to a floating pontoon/walkway, supported on steel piles, which is independent from the canal wall. This allows safe and level access to craft and to provide sufficient depth of water beneath moored vessels to prevent grounding.
Impact upon others
Surveys have been completed to verify sufficient depth of water is available and width of channel to accommodate the proposed berths, without impacting upon the minimum operating channel as designated by the Canal & River Trust.
Bluetech also ensure that the Risk Assessments and Method Statements (RAMS) are designed to ensure that at no point will the works (temporary or permanent) have an adverse impact upon navigational safety.
Due consideration has been given to the supply of materials and use of plant and equipment during the construction phase of the works such that no additional loading was applied to the canal walls adjacent to the works.
