Guernsey Water 2016 Annual Report EFFECTIVE DRAINAGE water.gg/ annualreport2016 13 Capital Investment Pumping Station Refurbishment We have completed some refurbishment work at our Belle Greve Wastewater Centre to ensure ongoing compliance with our discharge permit. We have also developed a proposal for refurbishment of our Gele Road pumping stationwhich has suffered from corrosion caused by Hydrogen Sulphide gas. Sewer Rehabilitation and Manhole Replacement We have lined 5km of sewer and refurbished manholes and covers at 30 locations during 2016. These rolling programmes are primarily targeted at the refurbishment of foul sewers and manholes at risk of blocking or collapse. Flood Mitigation We have provided flood mitigation measures to four properties which are at risk of internal foul flooding. La Piette Outfall We have carried out major cleaning and inspection of La Piette outfall. This reduces the risk of flooding to properties by discharging stormwater in the event of heavy rainfall. Further refurbishment is still needed and proposals will be developed in 2017. Operational Capital We have carried out refurbishment and replaced a number of failed culverts, chamber covers, lateral drains, valves and pumps as part of our operational capital investment programme. Business Performance Reportable Discharges Against Permit There was one reportable discharge from Belle Greve Wastewater Centre during 2016. Sewer Flooding Register Sewer flooding incidents reduced in 2016 largely due to there being fewer intense storm events. Business Initiatives ! 3 5 On Target = Satisfactory progress but not all 2016 tagets met = 2016 targets missed = Business Initiative Description Target Date 2016 Progress Performance CSO (Combined Sewer We will use instrumentation to 2016 The CSO monitoring system is in place and has been Overflow Monitoring) provide online monitoring of the connected into our SCADA system to give live alarm data. frequency, duration and volume However we’ve experienced unreliability in some of our of overflows from our wastewater installations; their performance will be assessed in 2017 to system. We will use this data to determine whether a different approach is needed. inform our bathing water management initiative (see Protect our Environment). Promote SuDS We will develop guidance for 2016 – 2017 Our SuDS Policy was completed during 2016 and received (Sustainable Drainage planners and builders to ensure endorsement from the Committee for the Environment and Systems) for Storm Water SuDS meet consistently high Infrastructure. Phase 1 of our exemplar SuDS retrofit scheme Management standards on new developments. at Vauvert School was completed and flow monitors We will retrofit SuDS proactively showed the pilot was successful. where they bring the most benefit. We will also promote SuDS that A proposal for a Surface Water Management Strategy was divert rainwater from our completed and work is due to start in 2017 to identify sewerage system as cost effective areas which will deliver greatest benefit from retrofit opportunities arise and adapt SuDS in the future. User guides for SuDS and our drainage systems to climate permeable paving were completed and will be made change bit-by-bit over time. available on our website in 2017. Wastewater We will continue to develop and 2016 – 2018 The wastewater hydraulic model is complete and is being Hydraulic Model maintain our wastewater hydraulic actively used to develop drainage solutions for new model. We will use it to develop housing development, flooding and pollution. programmes of investment to maintain and improve our sewerage system. Surface Water We will continue to develop our 2016 Steady progress has been made on the development of Modelling surface water hydraulic model. a surface water hydraulic model. So far effort has been We will use it to improve our focussed on a small pilot area in order to test the understanding of the interaction effectiveness of applying computational models to streams. between streams and our surface Progress has been slower than planned due to our water drainage network. deliberately cautious approach to using techniques developed for river modelling rather than our small streams. We have also used summer placement students to undertake surveys rather than more costly consultants. Hydrogen Sulphide Hydrogen Sulphide gas corrodes 2016 – 2018 Good progress was made in 2016 in reducing the peak Management our wastewater assets, can be the readings of Hydrogen Sulphide within the sewerage cause of odour complaints and network by dosing with a oxygenating bacterial product. is a health and safety risk to our Our new emptying point improvements at Les Huriaux employees and contractors. We have been designed to incorporate additional wastewater will manage it proactively by storage time to make this product more effective. learning from best practice elsewhere, monitoring and treating it. We will also rationalise and improve our cesspit emptying points to reduce hydrogen sulphide produced by cesspit waste. 3 3 3 ! !