What are the main challenges and risks of groundwater contamination in geotechnical engineering projects?

Groundwater contamination risks in geotechnical projects involve chemical spills, poor waste management, and inadequate sealing. Proximity to aquifers, stormwater runoff, and infrastructure leaks pose threats. Improper chemical use, lack of monitoring, and geological factors increase vulnerability. Changes in land use without assessment heighten risks. Mitigation requires rigorous site assessments, proper waste handling, and monitoring to comply with regulations, safeguarding groundwater quality in geotechnical engineering projects.

A preocupação da contaminação das águas subterrâneas está relacionada aos aqüíferos não-confinados, especialmente onde o nível freático é pouco profundo. para evitar qualquer contaminação das águas subterrâneas em camadas de pavimentação com o uso de ligantes asfálticos é fundamental o ensaio com sondagem à trado. Já para o uso de outros materiais mais nocivos como o rejeito de minério de manganês, além da sondagem à trado, faz-se necessário para verificar se há presença de chumbo os ensaios de lixiviação e flotação, para evitar assim a contaminação das águas subterrâneas.

Geotechnical engineering projects start with site investigation which include subsurface investigation by boring. Potential sources of contaminates are spill from petroleum products such as diesel, lubricants. Also, boring assessories may carry heavy metals on casings, drilling bits, etc., that are potential sources. In addition, boreholes not covered or sealed after work activity are conduit for murky surface water into groundwater sources to increase turbidity.

Groundwater contamination can stem from various sources such as industrial activities, agricultural practices, improper waste disposal, and leakage from underground storage tanks. For instance, in a geotechnical engineering project involving excavation near industrial sites, there's a risk of contaminants seeping into the groundwater due to disturbed soil layers.

Contaminants can alter the properties of soil, affecting its stability and load-bearing capacity. Additionally, groundwater contamination can render water unfit for consumption and harm ecosystems. In my experience, during a construction project, we encountered groundwater contamination from a nearby landfill, which compromised the soil's integrity and required extensive remediation efforts.

Groundwater contamination poses significant challenges for geotechnical engineers as it can impact the design and construction processes. For example, contaminated groundwater can weaken soil, leading to slope instability or foundation failure. In a recent project, we had to redesign the foundation system due to unexpected groundwater contamination, resulting in delays and increased costs.

O uso e aplicação da instrumentação hidrogeotécnica, a partir do projeto e implementação de uma campanha de instalação de instrumentos e de monitoramento é um aliado fundamental na prevenção e mitigação de contaminação de aquíferos e águas subterrâneas. Na engenharia geotécnica os instrumentos de monitoramento da condição da água em subsuperfície mais utilizados são o indicador de nível de água e o piezômetro. O indicador de nível de água, quando construído de forma adequada pode e deve ser utilizado para monitorar, além do nível freático livre, a qualidade da água, coletada a partir de amostradores específicos e ensaiada em laboratórios quimicos. Isso torna o indicador de nível d'água um instrumento multiproposito valioso.

Implementing preventive measures such as proper site investigation, groundwater monitoring, and installation of impermeable barriers can help mitigate the risk of contamination. Remediation techniques like soil vapor extraction and groundwater treatment may also be necessary if contamination occurs. In a project I was involved in, we installed a groundwater barrier to prevent contaminants from migrating into the construction site, coupled with regular monitoring to ensure its effectiveness.

With increasing urbanization and industrialization, the risk of groundwater contamination in geotechnical projects is likely to rise. Future challenges may include addressing emerging contaminants and implementing sustainable remediation technologies. In upcoming projects, integrating advanced geophysical techniques for early detection of contamination could become standard practice.

Geotechnical engineers can benefit from resources such as regulatory guidelines, technical publications, and case studies on groundwater contamination and remediation strategies. Professional organizations like the American Society of Civil Engineers (ASCE) and the International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE) often provide valuable guidance and resources in this area.