Wainscott Barracks

Upgrade to Water Distribution Network and Fuel Tank Removal

Whilst every so often jobs don’t always go according to plan, the recent mainlaying scheme for the MoD had its fair share of problems…………..

Waterlink were instructed during 2010 to undertake a complete replacement mainlaying scheme for Wainscott Barracks following a successful tendering process. Repeated bursts on the existing infrastructure, along with the ensuing cost of the water lost, necessitated the complete replacement of the pipework.

The works included installing 900m of 125mm MDPE pipe under heavily reinforced thick concrete around the site, with corresponding new supplies to all existing buildings. These supplies also required new points of entry and internal stopcocks to the buildings.

Much of the work was arranged and undertaken whilst the barracks remained fully operational.

As a result of preparing and cutting out the final trench area we found the edge of an underground fuel tank, necessitating total shutdown of the mainlaying activity pending further investigation. These investigations included initial ground radar, soil, water and air sampling to ascertain the concentration and extent of the hydrocarbon contamination. The radar survey in fact suggested there were two tanks closely adjacent to the newly installed main and the risk of hydrocarbon migration into the water supply meant both tank contamination sources would require removal.

underground petrol tankThe main was immediately taken out of service whilst concrete slab removal proved the scale and extent of the area affected by the contamination. Soil sample analysis showed that volatile petrol hydrocarbons had leached from the tanks for many years and that tracking, under the concrete slab, had taken place across the site in the general direction of the drainage system.

The tanks and contaminated ground removal involved the employment of expert sub-contractors which were supervised and managed by Waterlink. The excavation ended up being 5m x 6.5m x 3.5m deep and necessitated specialist trench shoring. Reinstatement using inert roadstone backfill was completed with 200mm double reinforced C40 concrete.

The final aspect involved replacing the originally installed MDPE main with similarly sized 125mm barrier pipe. This pipe is effectively two layers of plastic with an aluminium sandwich which acts as a physical barrier to the migrating petroleum hydrocarbons.

 

chattenden access hatch excavator pipework
finishing pipe identificiation action digger what we started with