Hydrogeological Impact Appraisal HIA
A hydrogeological impact appraisal (HIA) is a methodology designed to fit into the Environment Agency’s abstraction licensing process, including the changes brought about by the Water Act 2003. It also fits within the Environment Agency's overall approach to environmental risk assessment and can be matched to the risk of environmental impact associated with dewatering.
The HIA should include a conceptual understanding of the groundwater system and a survey to identify water-related features that could be affected by the dewatering e.g. water supply boreholes, rivers and protected sites. The assessment is backed up by calculations of the dewatering rates and the predicted impact (groundwater level drawdown) on nearby water features. A tiered approach is taken, with the level of detail, time and cost depending on the sensitivity of the site (presence or absence of rivers, protected sites etc.) and the scale of dewatering.
For sites where high dewatering rates are needed and/or in sensitive areas, the HIA may require extensive ground investigation, water features survey(s), pumping test(s) and stream/spring monitoring. This is likely to take several months. Once the HIA is completed and submitted, the regulator has up to four months to assess the application.
Additional guidance on HIAs is available through the Environment Agency.
[edit] Related articles on Designing Buildings
- Dewatering construction sites.
- Environment Agency.
- Environmental impact assessment EIA.
- Groundwater.
- Groundwater control.
- Hydrogeology.
- Raising awareness of dewatering regulation.
- Water abstraction licence.
- Water impoundment licence.
[edit] External resources
Featured articles and news
Guide to ISO 19650 for Architecture Firms (2026)
A user gives their low down.
A UK training and membership provider for mould remediation professionals.
Building Safety recap April, 2026
A short and longer run-through of the month, with links to further information and sources.
CIAT May 2026 briefing.
Independent NSI and BAFE study exploring how organisations are changing the way they buy fire safety services.
From medieval scribes to modern word art.
ECA welcomes crackdown on late payment and push for clean energy, whilst CIOB seek fixed cladding removal timeframes.
Cyber Security in the Built Environment
Protecting projects, data, and digital assets: A CIOB Academy TIS.
Managing competence in the built environment
ITFG publishes new industry guide on how to meet the ICC principles.
The UK's campaign to reduce noise pollution: Mythbusting, articles and topic guides.
Setting Expectations on Competence Management
Industry Competence Committee.
New Scottish and Welsh governments
CIOB stresses importance of construction after new parliament elections.
The sad story of Derby Hippodrome
An historic building left to decay.
ECA, JIB and JTL back Fabian Society call to invest in skills for a stronger built environment workforce.
Women's Contributions to the Built Environment.
Calls for the delayed Circular Economy Strategy
Over 50 leading businesses, trade associations and professional bodies, including CIAT, and UKGBC sign open letter.
The future workforce: culture change and skill
Under the spotlight at UK Construction Week London.
A landmark moment for postmodern heritage.