Cleaning up a contaminated site can cause protracted headaches for developers. But delays to construction can be avoided, writes Martin Richell
Frequently, the clean-up of a contaminated site can delay the start of construction work for months. Much to the annoyance of the developer, remediation projects can overrun, delay progress, or result in additional development costs over and above the original remediation budget.
Priorities for a developer are usually cost-certainty, timescale-certainty and
There are a number of ways to minimise the impact of a remediation project on site:
- Phasing the development, starting construction on areas not requiring clean-up
- Abandoning sustainable on-site remediation techniques for (increasingly more expensive) dig and dump options
- Using in-situ techniques within a small site footprint
- Using techniques that work fast
- Being innovative – combining risk assessment with remediation research and development to devise novel and innovative clean-up schemes
RAW Remediation has recently successfully completed the clean-up of a former filling station while development works were undertaken. Because of the relatively small size of the site, there was no room to phase the development, and mass dig and dump was ruled out due to the high cost of disposing of hazardous waste. Timescales for development of the site required overlap of the clean-up operation and the start of the construction works.
Consequently, a scheme was designed that allowed these needs to be met, based on in-situ treatment and use of risk assessment to minimise the necessary site works and associated timescales.
Cost benefit analysis, in addition to site-specific quantitative risk assessment, was used to identify the most appropriate remedial targets for the site. The scheme required the following elements:
- Removal of the tanks and selective dig and dump of grossly contaminated soil
- Risk assessment and design of the remedial scheme
- In-situ bioremediation by installation of small-footprint oxygen diffusion system
- Analysis of natural attenuation indicators in groundwater samples
- Modification of the remedial targets in line with the information collected during the remediation
- Regulatory sign-off of the completed remediation
- Small site compound for things such as dosing pumps and reagent storage, wellheads and hoses
- Careful routing of the infrastructure required (for example below roads)
- Sacrificial pipework can be installed around construction to minimise disruption
The developer was able to construct the foundations of the buildings without interference from the on-going clean-up. A small surface compound for the remediation equipment was used. Pipes and cables were routed away from key areas of the site. And injection wells were located where they would not be destroyed by the construction works.
And the remediation was completed before the programme finish through negotiation with the Environment Agency, and the use of cost benefit analysis and quantitative risk assessment.
By involving the remediation contractor as early as possible in the planning and programming stages, the clean-up can be designed and fitted around the development programme. The infrastructure required for the remediation can be designed to fit around the construction works, with key components such as:
Martin Richell is commercial manager for RAW Remediation
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