CIWEM: ‘ OVERVIEW The purpose of this guide is to assist water companies with best practice for EDM to comply with the conditions within a discharge permit. This guide collates current good practice on Event Duration Monitoring (EDM) of discharges from combined sewer overflows and other permitted storm overflows. Note that this document relates to EDM of discharges to the environment only and does not cover EDM of discharges to storm tanks which can be used to assess Pass Forward Flow (PFF) compliance. Emergency Overflows (including those which discharge to shellfish or bathing waters) are excluded from EDM as Emergency Overflows are only permitted to be active in emergency situations such as pump failure, not through typical operation. This document covers the provision of EDM including selecting which assets are included in EDM, monitoring equipment and location, data capture and storage, and reporting. Technical guidance is given for some aspects, whilst others are covered by having robust internal procedures in place to ensure consistency.
The contents of this document will be reviewed periodically, in the light of improvements in technological capability and any changes to regulatory requirements. The document is published for wider public and water industry benefit by CIWEM Urban Drainage Group and made available through its website. Subsequent updates will be curated by CIWEM Urban Drainage Group in collaboration with the industry.’