Scotland consults on hazardous discharges

The Scottish Environment Protection Agency has set out its approach to controlling the discharge of hazardous chemicals to water.

The Scottish Environment Protection Agency has published a consultation document on how it will implement controls on discharges of hazardous substances to water.1 The consultation ends on 18 July.

The document covers the introduction of the water framework Directive’s requirements on hazardous substances. These will gradually replace the 1976 Directive on dangerous substances, which will finally be repealed in 2013.

The water framework Directive cites 33 ‘priority substances’, including 12 ‘priority hazardous substances’ (ENDS Report 379, p 48 ). Environmental quality standards (EQSs) for all of these compounds must be met for waters to achieve good ecological status.

The consultation explains how SEPA will ensure these standards are met. It also covers the regulation of other ‘specific pollutants’ under the Directive that have standards set by member states, and the 1976 Directive’s ‘List I’ and ‘List II’ hazardous substances.

As a first step, SEPA will determine whether discharges are ‘liable to contain’ hazardous substances. This will be the case where the substances are listed in existing discharge consents, where they are detected above a reporting threshold in effluent, or known to be added to effluent as a result of on-site activities.

SEPA will set a numeric standard in discharge consents for discharges liable to contain hazardous substances where the concentration or load is significant. For the most dangerous substances - priority hazardous substances and List I substances - this will be where levels or loads are greater than or equal to a tenth of the EQS, or greater than or equal to SEPA’s reporting threshold on its pollution inventory. For priority substances, List II substances and specific pollutants the significant levels or loads are those greater than or equal to twice the EQS or five times the reporting threshold. Where concentrations or loads exceed these values, SEPA will monitor compliance with the standard. The charges imposed on dischargers are due to be reviewed this year and will reflect the costs incurred.

Numeric standards in consents will be set as concentration limits, but may also be set as loading limits. Limits will have two tiers as is current practice for ammonia or BOD in many sewage effluent consents: a lower tier limit to met 95% of the time, and an upper tier limit, typically twice the lower limit and applied at all times.

Consents will include a requirement to develop an action plan to reduce levels where discharges contribute to a breach of an EQS in a receiving water. There will also be conditions in all consents preventing rises in levels of listed dangerous substances.