The bridge in the middle of the village carries the A3028 over the River Avon, between Bulford and Durrington. After some 80 years of reliable service, the old bridge required an extensive re-build to ensure it could withstand increased local traffic movements as well as the high volume of heavy military vehicles moving from Bulford Camp to exercise areas on Salisbury Plain.
Construction works included complete replacement of the two bridge decks with parapet beams, a wider carriageway, a widened footpath, safety parapet, together with black-top finish. Bridge foundation upgrading called for a new piled northern abutment and new sheet piling to the perimeter of the central pier.
Bulford Village is at the confluence of the Nine Mile River and the River Avon and as such the river is of particular environmental importance with a wide variety of flora and fauna. Ringway, Wiltshire Council, and project consultants, Mouchel, met prior to commencing works to discuss ways to minimise the impact of the project on the sensitive surrounding environment.
It was identified that silt laden water and the high pH water created through contact with cementitious materials would be seriously detrimental to the ecology of the river. Having previously used Siltbuster technology on a number of projects, Ringway returned to the waste water specialists with a view to identifying the most appropriate solution. Siltbuster recommended the use of two HB50 settlement units, which enabled Ringway to clean silt laden water at the anticipated flow rates of in excess of 100m3/hr from a 6” pump prior to discharging treated water directly back into the river. Siltbuster HB50 settlement units are non-filtering, portable, hopper bottomed skid-mounted clarifiers that provide maximum settlement performance on sites where space is tight.
The risk to aquatic life through exposure to high pH water is well documented and, with copious quantities of concrete required to build the new bridge abutments and deck, Ringway took steps to minimise the risk of discharging concrete waste into the river. Ringway hired a Siltbuster concrete washwater system (RCW) to handle, treat and minimise the risk of polluting the river with concrete waste and its associated wash-water that results from the washing off concrete trucks.
David James, Ringway’s site manager, comments: “The Siltbuster settlement units and the RCW unit were very simple to set up and use and both did exactly what it said on the tin. Our client and the Environment Agency were very happy with the amount of silt that was collected and we plan to work with Siltbuster again in the near future.”
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