CE 3372 Water Systems Design

1. CE 3372 Water Systems Design Lecture 006: Introduction to US EPA-NET

2. Outline • EPANET Introduction/Workshop • Example problems • Network Design Principles • Introduction to Project

3. Workshop Install Example 1 – Flow between two reservoirs Example 2 – Three reservoir (branched) Example 3 – Two reservoir, 4 pipes (loop) Example 4 – Lifting with a pump

4. Model Preparation Sketch a layout on paper Identify pipe diameters; length; roughness values Identify node elevations; demands Supply reservoir (or tank); identify reservoir pool elevation Identify pumps; pump curve in problem units

5. Example 1 Example 2 – Flow between two reservoirs

6. Example 2 Example 2 – Three reservoir (branched)

7. Example 3 Example 3 – Two reservoir, 4 pipes (loop)

8. Example 4 Example 4 – Lifting with a pump

9. Network Design Principles • Water Supply System • Includes water supply • Treatment • Facilities • Pumping facilities • Transmission lines • Local distribution network

10. Water Supply system • Distribution network - Consists of items designed to convey potable water at adequate pressures and discharges • Pipes • Fittings • Valves • Other appurtenances

11. DESIGN • Who? • Personnel within the water company • Engineers / Consultants • Design parameters and regulations? • State board of health • Local city/county health departments • EPA, AWWA, ANSI

12. DESIGN REQUIREMENTS Pressure Velocity Age Chlorine concentration Fire Flow

13. Pressure • 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 state’s Health Department / other agency • Fire Marshall may establish additional requirements.

14. Fire flow • 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. Q = required fire flow in gpm C = coefficient related to the type of construction A = total floor area in ft2 (excludes basements)

15. Water supply system • 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

16. WATER utility • Water utility company • …who is responsible for the water quality and operation of the distribution system. • Companies exist in two forms • public entity that ..“exists for the health, safety, and welfare of the public” • privately owned utility that ..provides water for profit

17. 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

18. PipeSystem • 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

19. PipeSystem • 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

20. PipeSystem • 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

21. Water SUPPLY system

22. 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

23. 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

24. 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.

25. AssigningDemand • 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.

26. NetworkTypes • Branch • No circulation • Has terminals and dead-ends • Water in dead-ends is stagnant • Disinfection residual • Corrosion

27. NetworkTypes • 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

28. NetworkTypes • 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

29. Project • Semester design project is to conceptual design a water distribution system and a storm water sewer system for a small residential development • Hydraulic analysis for both systems to demonstrate that the systems will supply/convey as sufficient capacity

30. Estimating Flow Rate Demand estimation is used to determine how much water a system is likely to use (for sizing reservoirs and tanks Flow rate estimation (a plumber’s perspective) is used to determine how much capacity a system should be able to provide

31. How Much Water ? Inside home Meter to house • How Much Water Can You Actually Get? • Flow Rates are measured in gallons per minute (gpm). • For our purposes, we will talk about the amount of water that you can get through a pipe at a velocity of 8 feet per second (a standard velocity used to engineer a plumbing system). • Plumbing diameter will limit the flow rate you can get – the larger the pipe, the more water you can get. A home with 1″ plumbing can use substantially more water than a home with 3/4″ plumbing.

32. How Much Needed? (1) • 1. Think about the maximum number of fixtures and appliances you might operate at the same time. • 2. Look at the chart to see how many gallons per minute each device requires. • 3. Add up the flow rates for all the devices you selected. • You just figured out the PEAK FLOW RATE that you need. • Now, think about your continual water use, or water use that may run for more than 10 minutes. Add up the fixtures again, and you just calculated your SERVICE FLOW RATE.

33. How Much Needed? (2) • http://extension.psu.edu/natural-resources/water/drinking-water/best-practices/water-system-planning-estimating-water-use

34. Using the estimate • Estimate need per connection to size the system; • Run a hydraulic model at these values to size pipes • Estimate demand to evaluate how the system is likely to perform in terms of pressure zones and such • Run a hydraulic model at these values to check pressures – no fire flow • Run a hydraulic model with fire flow to check minimum pressures

35. Readings Several readings on server will be useful:

36. Next Time • Pumps • Review how to size • How to simulate in EPANET • NPSH considerations