||This provides a mechanism to understand the vulnerability of the sewer catchment (L3) to sewer flooding as a result of an extreme wet weather event (defined as a 1-in-50-year storm event). Catchment vulnerability score = 1 to 5 (where 5 is the most vulnerable or sensitive to an extreme wet weather event).
||Catchment vulnerability score = 4 or 5
(i.e. the most vulnerable or sensitive to a one in 50 year storm)
||Intermittent discharges impact upon bathing or shellfish waters
||This is a mechanism to understand the significance of any impact of water company operations on bathing or shellfish waters.
||Exceeding the permitted number of spills in each bathing water season, or per annum for shellfish waters.
||Continuous or intermittent discharges impact upon other sensitive receiving waters (Part A)
||This mechanism is to understand the significance of any impact of water company operations on sensitive receiving waters not addressed by other indicators.
||‘Remedy’ on Natural England’s Designated Sites system (associated with freshwater pollution discharges or freshwater drainage).
||Continuous or intermittent discharges impact upon other sensitive receiving waters (Part B)
||A mechanism to understand the significance of any impact of water company operations on sensitive receiving waters not addressed by other indicators.
||‘Threat’ on Natural England’s Designated Sites system (associated with water pollution).
||Storm Overflow Assessment Framework (SOAF)
||This considers the current / potential future activity to identify and address high spilling storm overflows.
||Are spill frequency investigation triggers likely to be crossed within next five years?
||Capacity Assessment Framework (CAF)
||The measure provides an indication of capacity constraints in the sewer network. There are accepted issues around the confidence in outputs from the Initial CAF model which does not include for surface water inputs.
||When categorised as 4 or 5 (due to performance, in full or part, within the catchment) will progress to the next stage of the process.
||Internal sewer flooding
||This is a common performance commitment by water companies to reduce flooding inside customer properties. It is a historical measure that records the number of internal flooding incidents per year, and it is indicative of capacity constraints within the sewer network.
||The number of incidents is more than one in total over the last three years (and other specific criteria depending upon size of sewer catchment).
||External sewer flooding
||This is a common performance commitment by water companies to reduce flooding within the external curtilage of customer properties. It is a historical measure that records the number of external flooding incidents per year, and is indicative of sewer capacity constraints.
||The number of incidents is more than 10 in total over the last three years (and other specific criteria depending upon size of sewer catchment).
||Pollution incidents (categories 1, 2 and 3)
||This is a historical measure that identifies incidents of unexpected release of contaminants that have resulted in environmental damage. Categorised in accordance with the 2017 definition in the Environmental Performance Assessment (EPA).
||For any of the previous three years data, a category 1 or 2 incident has occurred (see guidance for further details).
||WTW quality compliance
||This is a historical measure relating to the performance of the wastewater treatment works (WTWs).
||In any of the previous three years, the WTW discharge has been confirmed as failing and was included as such in the calculation of overall permit compliance.
||WTW dry weather flow compliance (DWF)
||This is a historical measure of compliance with DWF permits at WTWs.
||Has the Q90 of the measured yearly
flows exceeded the DWF
permit condition on two consecutive
years in the last five years? Or is the works at risk of exceeding its flow
||A measure that focuses on using available data to examine permit risks that have not been captured by other indicators (e.g. pass forward flow conditions).
||Is there evidence to indicate that over the last three years any overflow is not operating in accordance with permit conditions?
||Risks from interdependencies between Risk Management Authority (RMA) drainage systems
||A mechanism to understand risk posed by interdependencies / interactions between other RMA drainage systems in the catchment.
||Where it is considered that significant risks arise from interaction with other RMA drainage systems / receiving waterbodies.
||Planned residential new development
||A measure to understand the risks from forecast residential population growth in the sewer catchment.
||Planned residential development is greater than thresholds set out in the guidance.
||Water Industry National Environment Programme (WINEP)
||The WINEP sets out the actions that water companies need to complete to meet their environmental obligations. Where there are specific WINEP drivers it is considered necessary that a long-term approach to managing the issues is developed.
||Known WINEP drivers impacting the specific Level 3 catchment.
||This is a historical measure that identifies risks to the integrity of the sewer system.
||Sewer collapses are more than two per year in any of the preceding three years (see specific criteria in guidance).
||This is a historical measure that records obstructions in a sewer (that require clearing) which causes a reportable problem (not caused by hydraulic overload), such as flooding or discharge to a watercourse, unusable sanitation, surcharged sewers or odour.
||If the number of blockages (normalised by sewer length) in any of the preceding three years is greater than the company average.
||A measure of the number of customer complaints received in the catchment as an indication of ongoing or outstanding issues that are yet to be adequately resolved.
||Number of customer complaints.