BRD Environmental Ltd services

Phase 1 contamination assessments comprise the collation of desk based research together with the understanding gained from a site walkover. This phase of investigation provides an initial overview of the nature and extent of geotechnical or contamination hazards that may exist. The desk study typically includes a review of historical maps and aerial photographs, consideration of the geological and hydrogeological setting of the site from published sources, contact with regulatory authorities and retrieval of ground information from database resources. Desk studies are critical in revealing potential ground hazards such as mining hazards, landfill operations, nearby pollution incidents, naturally occurring radon gas, potentially contaminating land uses and pollution incidents. Desk studies also help to understand the wider environmental setting of the site so that potential receptors to contamination, such as groundwater resources, are identified.

Ground investigation involves the inspection of soils and rock layers by the excavation or trial pits and/or the drilling of boreholes.  Different techniques are applicable to different geology and site conditions.  The soils and rocks encountered are inspected by a supervising Geo-Environmental Consultant to provide a detailed engineering description of the ground.  Samples are obtained from the exploratory holes for laboratory analysis.

It is now common for planning permission to include a condition(s) relating to contamination assessment and remediation.  Such conditions are usually applied when the local authority has reason to believe that the potential development site may be affected by contamination such as previous industrial use.  Alternatively the planned development may be a sensitive land use such as residential and the authority wants to ensure it is safe for future residents.  Indeed, in some areas a contamination condition is applied to all residential development planning permissions regardless of the site’s former use.

If land has been polluted, then assessing the potential impact on human health is always of concern. BRD`s expertise in risk assessment can make sense of the numbers. Once a soil sample has been analysed by a laboratory, the concentrations for up to a couple of hundred different chemicals are presented in a table.  How do we understand all these numbers? The first step  to appreciate is that when assessing risk to human health from soil contamination it is considered on a suitable for use basis. In other words, whether the concentration of a particular chemical is of concern or not will depend upon what the land is to be used for. To some extent this is common sense, as most people can appreciate that a small child playing in a residential garden is a far more sensitive land use than an adult working in an office with limited landscaping.

Water quality is so precious and yet so often unappreciated, particularly the water that lies beneath our feet. BRD can assess the impact any contaminated soils may have on the water environment and identify what, if anything, needs to be done. We tend to take it for granted, but water is vital for our lives.  Protecting the quality of our water resources is just plain common sense. When assessing pollutants in soil we are often concerned with concentrations at parts per million (ppm), but with water even smaller amounts may be of concern at the parts per billion (ppb) level.  It is hard to imagine such small quantaties, but an example is that just a couple of tablespoons of petrol is enough to render a volume of water equvalent to an Olympic sized swimming pool  (50m by 25m by 2m deep) unfit to drink.

Various contaminants can represent a risk to the built environment and need to be considered in ground investigations. Adverse ground conditions can affect different building materials.  For example, ground gases may cause damage through explosions, fuel contamination can impact plastic pipes and naturally occurring sulphate can attack concrete.  All these aspects need to be considered during your geotechnical and contamination assessment.

Whether assessing Second World War bomb risk or investigating a military site BRD have the expertise to help. Two of our Principal Consultants are trained and experienced in ordnance recognition and safety supervision. BRD experience in this field can help identify when a specialist in the detection and clearance of Unexploded Ordnance (UXO) needs to be brought into a project team. BRD’s preferred patner when dealing with such sites is Zetica and together we have undertaken numerous joint projects for the benefit of our respective Clients.

The potential for a risk from ground gases is assessed at desk stage and, where necessary, the ground investigation will include the installation of monitoring wells in boreholes. These wells or standpipes comprise a vertical plastic pipe with slots cut across the depth range of interest, surrounded by a special clay (bentonite) seal near surface, fitted with an upper gas tap and finished with either a flush or raised metal cover. These wells are essential as it is important to monitor ground gases on several occasions as gas generation can be impacted by prevailing weather conditions. If a gas risk is identified at desk study stage, then a minimum of three wells and six monitoring visits are required although opions can obviously be expressed on less data.

Ground investigation and risk assessment for cemetery developments. Whilst not a subject many would care to dwell on, the natural degradation of animal or human buried corpses has the potential to cause contamination of groundwater resources. This potential therefore needs to be given due consideration during the planning of new cemeteries. One of BRD’s Principal Consultant’s experience working for the Environment Agency means that BRD understands what this key regulator is looking for when reviewing planning applications for such sites.