The Arley Consulting Company Limited

TACCL has long experience in undertaking flood risk assessments for development proposals in accordance with PPG25 and Environment Agency standards.

TACCL offers specialist hydrogeological services to the minerals, wastes management and water industries and the regulatory authorities including Groundwater Imaging Geophysics (EKS) and Environmental Tracing.

Regulations require quarry and landfill operators to know if groundwater resources may be affected by their operations. Farmers and landowners may wish to investigate the possibility off using local groundwater for irrigation, livestock watering or domestic supply.  The assessment, monitoring and management of groundwater is also important during civil engineering excavations.

The traditional method for determining whether there is useful groundwater is to sink boreholes and carry out pump tests.  Borehole drilling is very expensive and provides only a small 'snapshot' of the potential aquifer.  The borehole may also not be at the optimum location or depth for maximum yield.

TACCL offers a more cost-effective solution to groundwater detection and evaluation using 'electrokinetic geophysical surveying' or EKS.

EKS uses a traditional seismic method coupled to a state-of-the-art amplifier.  This converts very weak electrical responses from water molecules, vibrating in response to seismic shock, into an estimate of aquifer permeability and porosity comparable with estimates from pump tests.

Electrokinetic Surveying (EKS) offers several advantages over other geophysical methods:

  • If there is no EKS signal, it is certain that there is no groundwater.
  • Portability: two people can transport the equipment.
  • Cost effectiveness: 50-60 locations can be assessed for the cost of one investigation borehole.  EKS can also be used to provide detailed groundwater information between investigation boreholes.
  • EKS can provide a measure of electrical conductivity, important in the detection of leachate and other pollutant plumes moving within groundwater aquifers.
  • EKS will provide groundwater information in areas of high 'country noise'.  For example close to pylon lines, pumped sewers, and in wellfields.

Tracer tests are a valuable tool for carrying out pollution source-pathway-receptor studies.  They can be used to determine a connection between an injection point (eg stream sink or injection well) and are thus useful when undertaking groundwater risk assessments.

In conjunction with more detailed monitoring and sampling strategies, tracer tests can also be used to quantify groundwater flow rates and aquifer characteristics such as dilution factors that may affect pollutant attenuation and dispersion.

Specialist sampling and testing of groundwater for chlorofluorocarbons can indicate the presence or absence of landfill leachate long before concentrations of more usual contaminants are detectable.

Our staff and associates are experienced in the use of natural tracers (eg micro-organisms, environmental isotopes, chlorofluorocarbons, temperature) and artificial tracers (eg dyes and their intermediates, salts and other inorganic compounds) to 'label' the waters of interest.

Many tracers such as inorganic salts are toxic to fresh water ecosystems in the large quantities usually required.  Our service is focused on the use of fluorescent dyes.  These are the most practical tracers because they are typically non-toxic in the low (sub-visible) concentrations preferred and multiple traces are possible in the same catchment using different dyes thereby reducing monitoring and sampling costs.