HYDROGEOLOGICAL ASSESSMENTS

Hydrogeological Appraisal (HA) and Hydrogeological Risk Assessments (HRA) are seen as a minimum requirement for a range of groundwater matters. This includes the drilling of a borehole for abstraction, ground source or monitoring purposes; supporting an abstraction licence application to the Environment Agency; through to assessing risks of pollution of groundwater within a groundwater catchment.

Tapajos provides HA and HRA for a full range of hydrogeological needs, scaled to meet the complexity of the task, with the scope of the HA depending on the nature and scale of the problem and the anticipated risks. All stakeholders are consulted to ensure the HA and HRA have adequate scope in terms of the desk study, field investigation and data analysis components.

Short Report

A short desk study, site visit and report in advance of drilling a borehole is recommended. Tapajos can compile your HA to include:

  • Understanding of requirements - in terms of location, yield and use;
  • Geological assessment - general geology, lithology and structure
  • Hydrogeology - implications of the geology in terms of water bearing horizons, anticipated yield, hydraulic properties of each aquifer, groundwater flow direction, pathways and rates of flow.
  • Water use in the area - including other abstractors and the Environment Agency's classification of the aquifer in terms of availability of water and licence.
  • Neighbouring Boreholes and abstractions
  • Groundwater Quality Assessment
  • Catchment Assessment and Catchment Risk Assessment - an understanding of the anticipated groundwater catchment and risks to yield and quality, including the potential for planned activities to result in groundwater contamination and known or expected presence, distribution, concentration and risk from existing contamination.
  • Anticipated yield and quality of abstracted water
  • Initial Assessment of Health and Environmental Risk
  • Borehole design and Recommendations

Detailed Hydrogeological Appraisal and Hydrogeological Risk Assessments

Using the HA structure above, a more detailed HA may be required to plan for a larger groundwater source development, to reappraise existing licence abstraction, to support a licence application or re-licensing process; assess the impacts and risks of a known pollution hazard on groundwater abstraction or the aquatic environment; understand the hydrogeological regime (water table fluctuations, spring and ephemeral flows, abstraction yield and quality) or assess the suitability of an aquifer for future groundwater development.

The detailed HA typically comprises of the following tasks:
  • Understanding of requirements - in terms of location, yield and use;
  • Geological assessment - general geology, lithology and structure
  • Hydrogeological Setting - implications of the geology in terms of water bearing horizons, aquifers, aquicludes, anticipated yield, hydraulic properties of each aquifer, groundwater flow direction, pathways and rates of flow.
  • Aquifer availability- the Environment Agency's classification of the aquifer in terms of availability of water and licence.
  • Boreholes and abstractions in the catchment and region - including borehole logs and aquifer parameters (where known)
  • Data Collection and Collation
  • Groundwater Quality Assessment
  • Catchment Assessment - an understanding of the anticipated groundwater catchment
  • Catchment Risk Assessment -  and risks to yield and quality, including the potential for planned activities to result in groundwater contamination and known or expected presence, distribution, concentration and risk from existing contamination.
  • Anticipated yield and quality of abstracted water
  • Assessment of source, contaminant transport pathways and receptors for groundwater contamination 
  • Initial Assessment of Health and Environmental Risk
  • Conceptual Model
  • Borehole design, Groundwater Monitoring Network Design and Recommendations for future actions
Typically, a detailed HA will have the following outcomes:

A. New Source or Borehole development or enhancement:
  • no further action: if the aquifer is poor yielding or restricted in terms of future licensed development, HA may show it is unsuitable to design yield and borehole;
  • design and construction of a new borehole or groundwater source development based on an agreed design yield;
  • further HA, water level monitoring and possibly aquifer quality monitoring of contaminant risks identified
  • Dialogue with the Environment Agency and steps towards establishing new or enhanced abstraction licence 
B. Abstraction Licence Application to the Environment Agency:
  • no further action: if the aquifer is poor yielding or classed as Over Abstracted or Over Licensed by the Environment Agency, a view may be established that limits the proposed resource development;
  • design the new source development (if new borehole required)
  • design and undertake a pumping test for new or existing borehole based on an agreed design yield;
  • water level monitoring and possibly aquifer quality monitoring during pumping test;
  • Liaison and agreement with the Environment Agency;
  • Water Features Survey;
  • Statement of justification of need;
  • Revised HA and conceptual understanding in light of pumping test and monitoring data;
  • Dialogue with the Environment Agency to establish new or enhanced abstraction licence

C. HA addressing catchment contamination risks or groundwater pollution:
  • no further action: if the HA shows the risk from contaminant is negligible and future groundwater pollution is unlikely, then HA may show no action in terms of monitoring, clean up or risk mitigation;
  • ongoing management of groundwater contamination, including containment or monitoring;
  • further HA, monitoring and possible trials to clean up the aquifer where significant groundwater contamination occurs 
  • Ongoing dialogue with the Environment Agency to establish new or enhanced abstraction licence
  • ongoing groundwater clean-up to mitigate and restore damage to receptors.
Tapajos works closely with the client and environmental regulators to ensure the appropriate level of HA is established and agreed for the new borehole or source development or catchment risk.

HA and HRA can be applied to solve a number of hydrogeological problems. These include Groundwater Flooding, assessment of underground storage and foundations, impact of abstraction on low flows and other abstractors; and can be used to support abstraction licence applications, catchment assessments, borehole design and location and contaminant risks.



For more information, please contact:
                
                Email:  enquiries@tapajos.co.uk   

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