Water Distribution Systems, Network Systems CE 3372 WATER SYSTEMS DESIGN

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  • Water Distribution Systems, Network Systems CE 3372 WATER SYSTEMS DESIGN
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  • OUTLINE Review of Lecture 3 Water Distribution Systems Network Systems
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  • Define Hydraulics What is the Energy Equation Name some assumptions of the Energy Equation Difference in EGL and HGL 2 Main types of Head Loss 3 types of head loss models REVIEW
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  • Water Supply System Includes water supply Treatment Facilities Pumping facilities Transmission lines Local distribution network WATER DISTRIBUTION
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  • Distribution network - Consists of items designed to convey potable water at adequate pressures and discharges Pipes Fittings Valves Other appurtenances WATER SUPPLY SYSTEM
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  • Who? Personnel within the water company Engineers / Consultants Design Requirements? Pressure Fire Flow Potable water Cost Efficient $$ Design parameters and regulations? State board of health Local city/county health departments EPA, AWWA, ANSI DESIGN
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  • Pressures Must be high enough to.. overcome head losses in the system. But not too high to... prevent damage to fittings and other appurtenances. Pressure Zones Set pressurized areas (min and max) within the system by storage, boosters, or pressure control valves. Can also be due to varying pipe size and topography May be generated to ensure reliability in meeting fluctuation demands. System pressures are adapted to requirements. Hilly areas booster pumping Minimum pressures vary state to state Established by the states Health Department / other agency Fire Marshall may establish additional requirements. PRESSURE
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  • Fire Flow Parameters Each municipality establishes own parameters based on local cond. Insurance Services Offices (ISO) - Most used Guide for Determination of Required Fire Flow Recommends criteria for Establishing insurance rates Classifying mun. with reference to their fire defenses and physical cond. F = required fire flow in gpm C = coefficient related to the type of construction A = total floor area in ft 2 (excludes basements) FIRE FLOW
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  • Hydraulic Characteristics Pressures and discharges are a functions of HC Length Size Condition of pipe Service Characteristics Demand as it relates to: Present and projected population Economic base Fire flow Climate WATER SUPPLY SYSTEM
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  • WWater utility company who is responsible for the water quality and operation of the distribution system. CCompanies exist in two forms ppublic entity that..exists for the health, safety, and welfare of the public privately owned utility that..provides water for profit WATER UTILITY
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  • WATER SUPPLY SYSTEM Gravity Dependable Source of supply must be located well above the city High-pressure demand for fire-fighting may require pumper trucks Pump Least Desirable Pressures vary substantially with variations in flow Provides no reserve if power failure Pump with Storage Most common Water supplied at approximately uniform rate Flow in excess of consumption stored in elevated tanks
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  • PIPE SYSTEM Primary Mains (Arterial Mains) Form basic structure of the system Carry flow from pumping station to elevated storage tanks Carry flow from elevated storage tanks to service areas Laid out in interlocking loops Mains not more than 1 km (3000 ft) apart Valved at intervals of not more than 1.5 km (1 mile) Smaller lines connecting to them are valved
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  • PIPE SYSTEM Secondary Lines Form smaller loops within the primary main system Run from one primary line to another Spacings of 2 to 4 blocks Provide large amounts of water for fire fighting with out excessive pressure loss
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  • PIPE SYSTEM Small distribution lines Form a grid over the entire service area Supply water to every user and fire hydrants Connected to primary, secondary, or other small mains at both ends Valved so the system can be shut down for repairs Size may be dictated by fire flow except in residential areas with very large lots
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  • Water source (Main Supply) Lake River Aquifer Treatment Facility Treats and disinfects water Meet water quality standards Potable water Transmission Lines Convey water from source treatment facility facility network Pumping Facilities Provide energy to move water Intermediate Storage Facilities Stabilize line pressures Reserve for peak demand periods Provide storage for fire flow req. Distribution Lines Convey water from storage service areas Looped(grid) and Branched Layouts Appurtenances Fire Hydrants. Valves, auxiliary pumps, fittings WATER SUPPLY SYSTEM
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  • WATER USE SYSTEMS Spatial and temporal distribution in support of human habitation Water supply/treatment/distribution Waste water collection/treatment/discharge Capacity is based on POPULATION served hydraulic dominated designs
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  • WATER USE AND DEMAND Water Use Consumptive Municipal Agricultural Industrial Mining Non-consumptive Hydropower Transportation Recreation Water Demand Quantity that consumers use per unit of time Ex: Mgpd Depends on population, climate, industry and economic factors
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  • WATER DEMAND Residential Single-family, multi-family (apartments) Water for drinking, landscape, swimming, fires, street cleaning, etc. Usually two demand peaks (morning and evening) Commercial Motels, hotels, offices, shopping centers Usually less peak demand and less varied than residential Industrial Chemical plants, food processing plants, mines Water for fabrication, cooling, petroleum refining, etc. Water use depends on type of industr.
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  • ASSIGNING DEMAND Assign demand using network models (links and nodes) Network models contain nodes that represent a multitude of actual connections. While conceptually possible to model to every single connection, it is discouraged because Model is hard to maintain Small errors may go unnoticed The operation of any single connection is not well known.
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  • NETWORK TYPES Branch No circulation Has terminals and dead-ends Water in dead-ends is stagnant Disinfection residual Corrosion
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  • NETWORK TYPES Grid/Loop Furnishes supply from more than one direction Water circulates Disinfection is more effective. Water age in system is younger (fresher). In case of water main break, fewer people are inconvenienced
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  • NETWORK TYPES Loop vs. Branch during network failure Every link in a branch system is a single point of failure that isolates all downstream nodes. Not with loop, only main supply line is failed
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  • Distribution networks are multi-path pipelines Node Inflow = Outflow Energy is unique value Links Head loss occurs along line path BRANCHED SYSTEM
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  • Continuity at the node
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  • BRANCHED SYSTEM Head loss in each pipe Common head at the node
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  • 4 Equations, 4 unknowns Non-linear solve by Newton-Raphson/Quasi-Linearization Quadratic unknown can find solution in iterations BRANCHED SYSTEM
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  • TWO RESERVOIR EXAMPLE Refer to spreadsheet BRANCHED SYSTEM
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  • Looped system is an extension of branching where one or more pipes rejoin at a different node. LOOPED SYSTEM
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  • Nodes: Inflow = Outflow Energy Unique Links Head loss along pipe Head loss in any loop is zero LOOPED SYSTEM LOOP