Project proposal Methodology for Effective Operational Blockage Reduction

1. Project proposal Methodology for Effective Operational Blockage Reduction

2. Introduction • At present, water companies across the UK are facing detrimental environmental and customer problems arising from blockages within sewers. For example: • Blockages account for 80% of sewer flooding incidents in the UK and more than 3,000 properties are flooded each year as a result. • There are approximately 366,000 sewer blockages throughout the UK every year, of which up to 80% are caused by fats, oils and grease, wipes, sanitary waste and other unflushable items. • Approximately £88 million is spent annually on reactive blockage clearance nationwide, with further costs for clean-up after flooding incidents. • Thames water spends £12 million a year on the removal of fats from the network • Dwr Cymru Welsh Water (DCMM) on average sorts out 2,000 blockages per month within its sewer networks. www.wisecdt.org

3. Aim of the project There is a current need within welsh water for an optimised schedule for when the operational cleansing tasks such as jetting are to be performed efficiently and effectively. Water companies must convert to a proactive approach in treating blockages in order to keep up with increasing customer demands, stricter environmental policy, and in order to plan for long term renewal in a more sustainable way. Therefore the aim of this project is to determine the relationship between cleansing intervention and blockages, and the impact that weather and customer behaviour has on the formation of blockages. This research will therefore conclude when it is best to apply jetting to different parts of the network, which should result in reduced blockage rates in the future. www.wisecdt.org

4. Objectives • The main objectives of this project will be: • Improve the understanding of various factors impacting on blockage rates, including weather, customer behaviour and type/frequency/location of operational interventions undertaken, all in addition to more conventional factors studied before (e.g. sewer diameter, slope, FOG, etc.). • Develop a new methodology for cost-effective scheduling of operational interventions based on aforementioned improved understanding. • - Test/validate and demonstrate new operational methodology on real-life case studies and evaluate the resulting costs and benefits. www.wisecdt.org

5. Background The four principle blockage forming mechanisms Accumulation of fat, oil and grease (FOG) that eventually leads to a blockage within a sewer. Gradual build up of substance, can be treated with proactive approach. Build-up of silt deposition in low flow conditions within sewers can cause blockages. Proactive approach can be taken Snagging which occurs when debris such as tree roots catch on protruding objects and causes a blockage in the system. Occurs randomly. Othermiscellaneous reasons such as an equipment related issue. Occurs randomly. www.wisecdt.org

6. Background • Modelling of potential blockages • Traditional CCTV inspection of blockages are not pro-active enough currently in finding blockages due to a growing pressure of a constant 24 hour reliable wastewater network. • Previous academic work on modelling blockages has focused on: • Bayesian modelling • Factorial based models • Case-based reasoning • Evolutionary polynomial regression (EPR) • This thesis will therefore aim to develop potential models after deciding on the most appropriate model format to use. www.wisecdt.org

7. Background Blockage explanatory factors to investigate. The following explanatory factors have only been researched in relatively small urban areas or their relationship with blockage incidents has not been fully scrutinized or explored: Sewer characteristics Maintenance intervention Weather Customer behaviour and type This thesis will therefore aim to scrutinize the effects of these particular variables on blockages. www.wisecdt.org

8. Data sources • The initial data for this project will be made available by DCWW which includes an extensive dataset on blockages within Wales. More specifically the dataset contains the following information: • Previous blockage incidents reported by the customer including location (GIS) and type of blockage. • Previous schedules on which blockage incidents were given priority and when they were fixed, information that was provided to the crew during a blockage incident. • History of blockages of a property and calls from a property. • The response time from when a blockage was reported. • - CCTV from before and after incidents www.wisecdt.org

9. Methodology www.wisecdt.org Perform qualitative type analysis to improve understanding of various factors affecting different types of blockages with particular focus on weather, customer behaviour and type/frequency/intensity of jetting. • Collect data on historical blockages and related weather circumstances and operational interventions undertaken, relevant customers, sewer system assets etc. Perform preliminary analysis of this data to prepare it for the follow-on quantitative analysis • Perform quantitative type analysis (e.g. by mining, statistical, and GIS methods) with the aim to establish relationship and quantify the impact of different factors on blockage rates. This will be done separately for each type of blockage. Calibrate the dataset Based on improved understanding, develop new methodology for effective scheduling of operational interventions for reduced blockage rates by addressing a trade-off between relevant risks, costs and benefits. Plan and conduct field tests to collect data and further test the scheduling methodology. Finalise the methodology and perform validation on unseen field data. Apply the methodology to a smaller set of separate data to test its robustness when transferred or down scaled Quantify the uncertainty of the methodology and conduct a sensitivity analysis to assess the effect of the variables on the prediction accuracy of the methodology created. Estimate associated costs and benefits of the proposed approach.

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