Project: Management and Risk Assessment of a Cleaning Effluent Spill
Services: Spill response, environmental sampling, risk assessment, regulator liaison
Summary: Proportionate risk assessment and pollution management to safeguard local surface waters and satisfy regulator requirements
Approximately 800 litres of contaminated water, comprising spent floor washing effluent, was accidentally poured down a storm water drain on a large engineering/storage facility. ESI was commissioned to assess the risks posed to the freshwater environment from the accidental effluent release and subsequent discharge to a nearby pond and associated surface water channel. Salient recommendations were also required for managing the effluent release, including the specification of appropriate remediation/clean-up activities.
The emergency response actions coordinated by ESI included:
- A site visit within several hours of initial client communications. The visit comprised an inspection of all local surface water features, drainage inspections, data collation and discussions with the site operations manager.
- Review of drainage plans and verification of the drainage lay-out ‘on site’ in order to confirm the location of all drainage outfalls and thus to identify all potential contaminant receptors.
- Placement of absorbent matting and booms around the drain discharge point.
- Water sampling from the pond and appropriate chemical testing (including full surfactant analyses and a measure of chemical and biological oxygen demand) in order to establish residual pond water quality.
- Liaison with the Environment Agency.
An assessment of the risks posed to the freshwater environment was undertaken by comparing observed water quality with relevant target concentrations, derived from published UK water quality standards. No appreciable water quality impacts were identified. As such, the absence of any appreciable surfactants suggested that the effluent released into the storm drain was unlikely to have a lasting effect on the balancing pond.
Various petroleum hydrocarbon compounds were however detected at modest concentrations within the pond water. These concentrations likely reflected the quality of water being routinely discharged into the pond due to the entrainment of various contaminant sources including road runoff, miscellaneous wash down effluent, minor fuel leaks and spills, etc.
No remediation activities were recommended in order to manage the effects of the effluent release. However, in order to assess the potential medium-term effects of any ongoing ‘routine’ contaminant loading into the pond a six month programme of surface water quality testing was advocated.