Asset Condition
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A measure of deterioration in the physical state of the asset when compared to its new state.
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Asset Maintenance
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The management of deterioration. This includes repairs to maintain asset performance and elements of operational maintenance to prevent excessive deterioration.
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Asset Management
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Maintaining the service capability of asset systems at optimum economic level, to safeguard the flow of services into the future, at a level of risk and price that is acceptable.
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Asset Performance Indicator
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A quantity that reflects the performance of an asset or group of assets in fulfilling their intended function. (UKWIR).
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Capital Maintenance
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The renewal or refurbishment of capital assets in order to provide continuing service to customers and the environment consistent with current regulatory obligations.
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Catastrophic Rainfall Event
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Rainfall event of return frequency far in excess of any sewerage design performance criteria typically, say a 1 in 200 year storm.
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Cost-benefit
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The comparison of the present value of all benefits of a project with the present value of all costs. Where this ratio exceeds 1, the project has positive benefits.
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Cost Effective
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The economic comparison of the costs of providing solutions to achieve a given standard to ensure that the solution with the lowest economic-cost is chosen.
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Cracks
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Crack lines visible along the length and/or circumference of a sewer pipe.
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Design Standards
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A set of values to use for the engineering design of new (greenfield) or rehabilitated sewer systems or compoent parts thereof. They will normally include an allowance for future growth, asset deterioration or other factors such as climate change.
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Drain
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Pipe carrying wastewater from a building or buildings a single curtilage.
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Drainage Area
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A discrete spatial unit for the analysis of one or more aspects of the performance of a sewer system, with recognised interfaces to a WwTW(s) and receiving watercourses.
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Exfiltration
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The escape of flow from a sewer into the surrounding ground.
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Flow Attenuation
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The process of reducing the peak flow rate in a sewer system by redistributing the same volume of flow over a longer period of time.
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Flow Reduction
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The process of decreasing flows into a sewer system or removing a proportion of the flow already in a sewer system.
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Flow Simulation
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The modelling of flows in surface water or combined sewer systems using a dynamic digital model.
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Formula A
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Formula for calculating "carry-on" flow at a storm water overflow recommended by Technical Committee on Storm Overflows and the Disposal of Storm Sewage, 1970.
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Fractures
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Cracks, visibly open along the length and/or circumference of a sewer pipe with the pieces still in place.
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Headroom
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The capacity of the system to take increased demand. It can be considered to be the difference between the actual Level of Service and a relevant benchmark Level of Service.
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Highway Drain
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A pipe vested ina highway authority primarily used for the drainage of a highway.
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Infiltration
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The entry of groundwater into a sewer system through the pipe work, often considered in conjunction with inflow.
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Inflow
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The entry of unplanned flows into a sewer system via manholes or misconnections, often considered in conjunction with infiltration.
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Integration
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The joint consideration of the various performance aspects of a sewer system - hydraulic, water quality, structural and operaitonal.
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Intervention
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Any activity relating to sewerage assets that involves maintaining or improving performance including all rehabilitation and activities such as sediment and root removal.
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Lateral Drain
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That part of a pipe conveying wastewater from a building or buildings witin the same curtilage to a sewer that is outside the curtilage of the buildings it servces.
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Operational Maintenance
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The carrying out of standard tasks needed to maintain system performance. An example is clearing blockages.
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Optimisation
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The process of achieving the most justifiable balance between all aspects of performance and total costs.
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Performance Indicator
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See Asset Performance Indicator.
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Rehabilitation
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All aspects of upgrading the performance of existing sewer systems.
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Reinforcement
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The provision of an additional sewer, which in conjunction with an existing sewer increases, overall flow capacity.
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Renewal
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Construction of a new sewer, on or off the line of an existing sewer, the basic function and cpacity of hte new sewer being similar to those of the old.
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Renovation
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Methods by which the performance of a length of sewer is improved by incorporating the original sewer fabric, but excluding maintenance operations such as root or silt removal.
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Repair
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Rectification of damage to the structural fabric of the sewer and the reconstruction of short lengths, but not the reconstruction of the whole of the pipeline.
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Replacement
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Construction of a new sewer, on or off the line of an existing sewer. The function of the new, on or off the line of an existing sewer. The function of the new sewer will incorporate that of the old, but may also include improvement or development work.
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Risk
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A combination of the probability of (asset) failure and a forecast of the severity of the direct and indirect (consequences) of (asset) failure on the level of service to customers and the environment.
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Service Indicator
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A quantity, which may be measured, calculated or estimated in order to provide an indication of a particular aspect of the service being provided by a utility to customers and the environment.
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Service Standard
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A benchmark level service. This can be a statutory requirement but need not be so.
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Serviceability
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The capability of a system of assets to deliver a reference level of service to customers and to the environment now andin the future (UKWIR).
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Serviceability Indicator
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A service indicator or asset performance indicator.
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Sewer
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Pipe conveying wastewater from buildings comprising more than one curtilage.
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Sewerage Management Plan
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A busiiness plan covering all aspects of sewerage performance related expenditure for a defined number of years and covering a complete drainage area and considering all relevant stakeholders.
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Social Costs
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Costs incurred by society as a whle as a result of sewerage works or performance failures.
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