News
The site of the old Swindon Police Station, which was demolished earlier this year to make way for The Exchange development part of The New Swindon Company's plans for regenerating the town centre, is to undergo a 'green' clean over the next few months.
The former Divisional Police Headquarters included an underground fuel tanks used for refuelling police vehicles initially with petrol, and later diesel following a conversion. Over the years of operation on the site a mixture of both diesel and petrol (known as hydrocarbons) seeped into the surrounding soil and groundwater, causing both to be classed as contaminated. This means that they must be either removed from the site or 'cleaned up'.
The main elements of the clean up project are the removal of the old fuel tanks and associated pipe work, cleaning of the surrounding soil by bio-remediation and removal of the hydrocarbons in the groundwater by pump and treat.
All of the clean up processes used on the site apply enhanced natural methods for decontamination.
Mini Bugs do the work
The contaminated soil from around the tank installation will be excavated and moved to a controlled area on the site ready for bio-remediation. This involves the controlled and accelerated action of the natural microscopic organisms, called microbes, in other words mini bugs, within the soil breaking down the hydrocarbons into CO2 and water. This kind of activity, called microbial action, occurs naturally in any soil, however by constantly aerating the soil and controlling the level of moisture and nutrients the process is sped up considerably.
This can be seen on the police station site by the soil being placed into long piles called bio-piles, which will be constantly monitored and aerated and if required watered to provide the ideal conditions for the bugs to do their job. During this period tests will continuously be done until the agreed reduction in the hydrocarbons have been attained enabling the soil to be re-used on the site.
With all the excavation on the site groundwater will be encountered. To clean up this water, which previous tests have shown has been contaminated with hydrocarbons, it will be pumped to a special treatment area set up on site. This treatment area will include settlement ponds, an oil-water separator and a water treatment unit known as a Granular Activated Carbon unit if required. Once the groundwater has been cleaned to an acceptable level it can then be discharged into the sewers under licence.
The current site owners, the South West RDA (SWRDA), one of The New Swindon Company partners, are working closely with the previous owners and operators of the site at the time of the contamination, Wiltshire Police Authority,
who have taken responsibility of undertaking the remediation (clean-up) works required.
The New Swindon Company is keen to ensure that the development of The Exchange has as little impact on the environment as possible. The work will be done by specialist contractor, Santus Ltd, with Intergrale acting as Contract Administrators and Independent Validator, Ridge and Partners as Planning Supervisors and White Young Green Environmental will independently monitor the work on behalf of SWRDA.
Work will start in the Autumn and is scheduled to take 20 weeks with the first four weeks being fairly active with the water clean up taking place. The site will then be limited to very minimal activity with the turning of the Bio-piles and ongoing monitoring.
Monday 16th October 2006