We actively help clients to sell or acquire sites, supporting the due diligence process by investigating and assessing risks attached to land, including asbestos, that may have a history of contamination both in the soil and the groundwater. At Hydrock, we believe that legacy contamination issues should not be assessed and remediated in isolation but need to be addressed alongside the earthworks solution and any geotechnical risks.
By characterising site conditions in detail we are able to deliver a commercial and sustainable solution to clients that enables them to extract maximum value from a site. Our teams have strong relationships with all the regulatory authorities and are well versed in negotiating appropriate agreements to remediate sites on a practical and cost effective level.
Our UK-wide team also includes four independently-accredited SiLC’s (Specialist in Land Condition), the most experienced and qualified level of specialism that can be obtained in this field.
Focus on sustainability
As we devise remedial strategies based on our detailed site investigations, we ensure that the most sustainable remediation methodologies are selected to minimise cost and environmental impact.
Our focus is on minimising disposal to landfill, keeping lorry movements to a minimum and maximising re-use of arisings and site-won materials.
To this end, Hydrock is a member and sponsor of CL:AIRE, an independent organisation that promotes sustainable remediation whom we worked with to develop their Definition of Waste: Development Industry Code of Practice.
We design investigations to determine the range and concentration of potentially harmful substances in the underlying soil and groundwater, and the potential for the presence of ground gases. Our investigations are usually designed to also obtain geotechnical information for a proposed development.
The first stage is a ‘Phase 1’ desk-based study and site walkover survey during which all currently available information about the site is compiled to form a preliminary conceptual site model. This model will identify potential contaminant linkages that require further investigation by undertaking intrusive investigation and monitoring.
These onsite ‘Phase 2’ investigations will involve excavating trial pits and/or drilling boreholes. Samples of soil and ground and surface waters are taken for chemical testing, groundwater is monitored to determine flow direction and velocity, and ground gas concentrations and flows are also measured.
We take responsibility for the procurement of all plant and equipment to undertake the investigations, and we deploy qualified and experienced staff to supervise the works. Health and safety standards are of paramount importance, and all works are preceded by preparation of a Risk Assessment and Method Statement.
Following laboratory testing of soil and groundwater samples, our report on findings will form the basis of the subsequent risk assessment.
The risk assessment will identify and evaluate unacceptable risks associated with contamination in the context of the current or proposed use of the site.
A preliminary risk assessment is undertaken during the desk study primarily for initial due diligence and to form a view on follow-up investigations. Key facts about the site are collated and interpreted, for example relating to the geology, hydrogeology and history of contaminative use.
The soil and groundwater chemistry data gathered during the intrusive investigation is subjected to a generic quantitative risk assessment. Where potentially unacceptable risks are identified, the data may be subjected to a detailed quantitative risk assessment to evaluate site-specific risks and this information may be used to determine remedial target values.
All risk assessment tools used by Hydrock are leading-edge accredited methodologies recognised by the regulatory authorities as providing reliable results based on sound science.
Part 2A obligations
This commonly used abbreviation describes the requirements of Part 2A of the Environmental Protection Act 1990.
Its relevance is that it imposes a duty on local authorities to inspect land under their jurisdiction to determine if it is contaminated and if it has the potential to cause significant harm or significant possibility of significant harm (SPOSH) or significant pollution of controlled waters or significant possibility of significant pollution of controlled waters (SPOSPOCW). If the land is determined to be contaminated, the local authority has the power to enforce remediation by the appropriate person via a remediation notice.
At Hydrock, we have worked for numerous local authorities across the UK, investigating and evaluating sites and providing advice on our findings. The sites are subject to investigation and risk assessment to determine if significant harm or SPOSH applies, although results are evaluated in accordance with more recent guidance, which takes account of socio-economic factors as well as technical ones.
These projects are frequently in residential settings, which requires much sensitivity throughout the programme of activity.
If significant pollution of controlled waters or SPOSPOCW is determined, responsibility for the regulation of the site stays with the local authority unless the site meets certain criteria which make it a ‘Special Site’, in which case the Environment Agency becomes the lead regulator.
Remediation options appraisal, agreement and design
Some form of remediation is likely to follow from the identification of unacceptable risks.
A Remedial Options Appraisal will identify the options that are technically capable of breaking any relevant contaminant linkages. Each option is evaluated to select the one that provides the most sustainable solution in terms of cost, programme, environmental impact, etc.
Having selected a preferred remedial option, the scheme is put forward as a remediation strategy for discussion and approval by the regulators. The approved strategy then provides the basis for a Detailed Remediation Method Statement (DRMS) that is capable of being translated into a contract document for works implementation.
We always aim to minimise off-site disposal of materials and this can be facilitated by the development of a Materials Management Plan written in accordance with the CL:AIRE Definition of Waste: Development Industry Code of Practice. In addition to this, any remedial techniques to treat contaminated soils and waters will be subject to environmental permitting legislation.
The DRMS will also contain proposals for verification of the remediation works on completion.