Water Supply Coverage (2000)

Global Water Supply and Sanitation Assessment 2000 Report(WHO and UNICEF)

0%~25%25%~50%51%~75%76%~90%91%~100%Missing data

Water supply coverage

0%~25%

25%~50%

51%~75%

76%~90%

91%~100%

Missing data

Sanitation coverage

Sanitation Coverage (2000)

Global Water Supply and Sanitation Assessment 2000 Report(WHO and UNICEF)

Conventional Water Treatment Process

3

Direct Filtration Process

4

In-Line (or Contact) Filtration Process

5

Two-Stage Filtration

6

High-Level Complete Water Treatment Process

7

Conventional Two-stage Direct In-line

complete filtration filtrationfiltration

Turbidity (NTU) < 5,000 < 50 < 15 < 5Color (apparent) < 3,000 < 50 < 20 <

15Coliform (#/mL) < 107 < 105 < 103 <

103

Algae (ASU/mL) < 105 < 5 × 103 < 5 × 102 < 102

Asbestos fiber (#/mL) < 1010 < 108 < 107 < 107

Taste and odor (TON) < 30 < 10 < 3 < 3

• The criteria shown are a general condition.• If the raw water turbidity exceeds 1,000 NTU, a

presedimentation process is required for all conventional complete treatment processes.

Applicable Raw Water Quality for the Basic Treatment Processes

8

Constituent Separation Processes

Algae Straining, coagulation-sedimentation, coagulation-flotation, oxidation-filtration

Bacteria, pathogenic Coagulation-sedimentation, adsorption, ultrafiltration

Calcium Precipitation-sedimentation, ion exchange, reverse osmosis

Chloroform Adsorption, gas stripping, reverse osmosis

Clays Coagulation-sedimentation, ultrafiltration

Fluoride Precipitation-sedimentation, adsorption

Humic acids Coagulation-sedimentation, adsorption, ultrafiltration, reverse osmosis

Iron, ferrous Oxidation-filtration, reverse osmosis

Mercury Coagulation-sedimentation, adsorption, ion exchange

Nitrate Ion exchange, biological reduction, reverse osmosis

Phenol Oxidation, adsorption

Salts, dissolved Distillation, freezing, ion exchange, reverse osmosis

Sulfate Ion exchange, precipitation-sedimentation

Alternative Separation Processes for Removal of Constituents from Water

9

Strainer

10

Separation of clays, bacteria, algae

Reduction of Gibbs interfacial free energy, size

Unconsolidated inert solids

Granular media filtration

Lime-soda softening, Fe and Mn removal

Nucleation, insolubility of solid

Chemical oxidant, excess precipitant, pH

Precipitation

Dewatering of sludgeWater evaporation and diffusion

HeatDrying of solids

DemineralizationDiffusionSemipermeable membrane and pressure gradient

Reverse osmosis

Water softening, removal of nitrate

Chemical equilibriaSolid exchange resinIon exchange

Removal of organics, trace metals

Different in Gibbs free energy

Solid adsorbentAdsorption

Addition of CO2, Cl2, O3 to water

Phase equilibriaNonvolatile liquid (e.g., H2O)Absorption

Removal of dissolved gases (H2S, CH4, NH3)

Phase equilibriaNoncondensible gas (e.g., air)Stripping

DesalinationVapor pressureHeatDistillation

Examples in Water Treatment/ Reuse

Principle of Separation

Separating AgentProcess

Selected Physicochemical Separation Processes

11

Air Stripping

12

13

Process Separating Agent Principle of Separation

Examples in Water Treatment/Reuse

Ultrafiltration Membrane and pressure Molecular size Organic removal

Sedimentation Gravity Size, density Solid-liquid separation

Flotation Gravity, rising or attached air bubbles

Size, density Solid-liquid separation

Thickening Gravity Size, density and structure

Liquid-solids separation, e.g., alum sludge

Centrifuge Centrifugal force Size, density Dewatering of sludges

Cake filtration Cloth or metal membrane, vacuum or mechanical pressure

Size Dewatering of sludges

Screening Metal screen, various size openings

Size Microstrainers for algae removal

Selected Physicochemical Separation Processes

14

Design Flowrate for Waterworks

Water treatment processes including intake facility: Qmax-day

Plant hydraulic capacity: 1.25 to 1.5 Qmax-day

Clearwell capacity: 0.2 Qmax-day

or fire fighting capacity (local code)

High service pump station: Qmax-day

Water distribution reservoir (in the city): Qmax-day

Notes: Qave-day = average annual daily flow rate

Qmax-day = 1.5 Qave-day

Qmax-hr = 1.5 to 2.0 Qmax-day

Qmin-day = 0.25 Qave-day

15

Pipe Size Selection for Waterworks

Raw water main: 6 to 7 fps (1.8 to 2.1 m/s)

Flocculated water line Conventional treatment with rapid sand filter: 1~1.5 fps (0.3~0.45 m/s) Direct filtration or conventional with multimedia filter: 3 fps (0.9 m/s)Filter influent line: General: 2.5~3.5 fps (0.75~1.05 m/s) Polymer-fed filter influent: 3.5~4.5 fps (1.05~1.35 m/s)Filter effluent line: 5~6 fps (1.5~1.8 m/s)Filter wash water main: 5~6 fps (1.5~1.8 m/s)Wash waste main: 6 fps (1.8 m/s)Distribution main: 6 fps (1.8 m/s)Pump suction line: 4~6 fps (1.2~1.8 m/s)Pump discharge line: 7~9 fps (2.1~2.7 m/s)

16

Water Treatment Plant Design

Cost: 5 - 10% of the estimated construction costTime: 9 - 12 mos. for design; 2 yrs for constructionEuropean & Asian practice1. More freedom in process selection, siting, control mode. 2. Determined by the quality and adequacy of the proposal

and the estimated design and construction costs.American practice1. Complete > 80% of design before bidding.2. Submit a complete proposal including drawings and specs.3. More thorough predesign studies such as alternative

process evaluation and site selection.

17

Selection of Consulting Engineer

Consulting Engineer: A professional who is experienced in applying scientific principles to engineering problems.

Selection procedure1. Issue a request for qualification (RFQ)2. Select three to five firms3. Issue a request for proposal (RFP)4. Select the most qualified firm and a backup firm5. Negotiate the fee and a detailed scope of workImportant selection points: technical qualification,

personality and administrative skills of key engineers, existing work load, experience, reputation, past accomplishment, financial stability, etc.

18

Fee Structure

1. Salary cost times a multiplier, plus other direct costs

• Used when the work scope cannot be defined accurately

- Salary cost Payroll factor (1.3~1.4)

A multiplier (2.3 - 2.5)

e.g., $25/hr 1.3 2.4 = $78/hr

- Other identifiable costs + 10 ~ 15% service charge

• Little chance of losing money

19

Fee Structure (continued)

2. Costs plus a Fixed Fee• Used when the work scope cannot be defined accurately. Yet define the work scope as completely as possible. • Reimbursable costs include the technical payroll and actual expenditures that are directly incurred for the project.• The fixed fee includes the profit, nonallowable costs (e.g., contingencies, interest on invested capital, and availability of the consulting team), allowable costs (e.g., direct labor, direct project costs, and indirect costs incurred by the labor base)• A percentage of the engineering costs - 10 ~ 25%

20

Fee Structure (continued)

3. Fixed Lump Sum Fee• Used when the work scope is well defined. • Estimate the work-hours required and the anticipated cost for rendering the service.• The contract includes a time limit for the service and a provision for adjusting the fee.

4. Percentage of Construction Cost• A variation of the fixed lump sum fee.• Was popular in the past.• Fee is based on the reputation of the firm and the customary percentage by the industry.• Not recommended for plant expansion projects.

21

Bench Scale Studies

Objectives:1. Optimization of chemical coagulants2. Chemical application sequence3. Confirmation of proper mixing conditions for flocculation4. Estimation of hydraulic surface loading for sedimentation

by measuring floc settling velocities5. Potential trihalomethane (THM) production6. Control of taste- and odor-producing compounds by

oxidants or activated carbon• The Phipps and Bird jar tester is most commonly employed. • 200 work-hrs are required.

Bench Scale Studies (continued)

22

23

Pilot Plant Studies

• Necessary part of the design process due to use of non- conventional treatment processes, increasing costs of plant construction, and the emergence of new water treatment technology

• Costs from $100,000 to $1,000,000• Select the most appropriate type and best manufactured

equipment• Must be operated by highly qualified personnel for at

least 6 to 12 months.¶ Must establish study objectives, duration and cost of

the experiment, availability of equipment and technical staff, and important variables of the study.

24

Pilot Plant Studies (continued)

Objectives:1. Obtain permits for nonconventional processes.2. Evaluate the practicability of a new treatment process.3. Compare the effectiveness of alternative processes.4. Obtain a guide for process design criteria, operational

parameters, and operating costs.5. Improve existing processes.6. Investigate the cause of problems.7. Confirm the effectiveness of the proposed treatment

process.8. Discover unforeseen problems.

25

Pilot Plant Studies (continued)

Major problems:1. Difficulty in testing the raw water on a year-round

basis2. Use of an improper type of clay when simulating

abnormal raw water conditions (high turbidity)3. Use of raw water stored for over 1 to 2 days4. Differences in operational conditions (pilot vs actual

treatment plant)5. Problems encountered in scale-up6. Failure to foresee long-term effects of the new

process7. Conclusions biased by personal expectations

26

Project Control

1. Assign a job number to the project. e.g., 99-WT12. Prepare a contract brief, billing summary, and a budget

worksheet.3. Create project files.4. Prepare a control schedule, including the period of activity,

the budget for each activity, meeting dates for coordination, a final check date, etc.Critical Path Method (CPM), Program Evaluation and Review Technique (PERT), Integrated Budget and Schedule Monitoring Technique (IBSM)

5. Investigate all requirements established by local, state, and federal agencies.

Integrated Budget and Schedule Monitoring

27

28

Bar Chart

While the duration of each task is easily shown, the sequence between tasks can not be easily shown. Sequence is not well shown on Bar Charts.

29

Critical Path Method (CPM)

• A management tool for controlling the progress of any large project where completion on time is important. The method works by breaking down the large project into activities or tasks each with a time allocation. These activities are then logically represented on a network showing their interrelationships in a chronological fashion. As each activity has a time allocation the completed network shows the critical path of activities which must be completed on time if the whole project is not to be delayed. It is also possible to identify the earliest and latest start times for each activity if the overall project is not to be delayed.

30

• Project tasks (activities): arrows• Circles at the beginning and end of activities: nodes - Pairs of

nodes are used to identify each activity. • Showing sequence in arrow diagrams often requires the "logic

dummy." To show that Activity D precedes both Activity F and Activity G, a logic dummy will be required.

Critical Path Method (CPM) - continued

Line-of-Balance MethodUseful for projects where similar work is to be accomplished through a range of work areas, e.g., highways, civil works job, mid- or high-rise building projects and multi-unit housing construction.

The slopes of each of the activity lines shows the productivity of the crews as they move through each area of the project. Notice that Activity B, which has a high productivity per work area is not a continuous line. A broken line shows idle time for workers as they wait for the crew before them to finish an area. 31

32

Project Control (continued)

6. Organize a project team.7. Arrange for all necessary outside services such as soil

analysis and site survey.8. Select the technical advisory committee and the value

engineering team.9. Determine the number of technical advisory meetings.10. Prepare a memo after each meeting.11. Encourage active input from the client and keep the client

informed on the progress.12. Review the cost of the project at the end of each month.13. Prepare construction specifications.

33

Project Control (continued)

14. Check the completed drawings and specifications by the project engineer (red lined) and an independent checker (yellow lined).

15. Edit the bid documents and submit the preliminary drawings and specifications to the client for review.

16. Arrange an estimate for the construction costs.17. Schedule the production of construction documents.18. Obtain signatures from the company officer and the

client.19. Present the final drawings and specifications to the client

and the appropriate governmental agency.20. Arrange for the advertising of bids and bid openings.

34

Typical Design Team

35

Preliminary Studies

Feasibility Study1. Planning period: 10 ~ 20 yrs2. Water supply areas3. Future population4. Maximum daily water demand

Average annual rate: 100 (80~130) gal per capita per dayMaximum daily demand: 150% of avg. annual rate

5. Evaluation and selection of the water source • River, lake, artificial reservoir, groundwater, reclaimed

sewage or seawater, etc. • Quantity, quality, climatic conditions, operator safety,

minimal operations and maintenance costs, potential future contamination, easy intake expansion

36

Preliminary StudiesFeasibility Study - continued6. Size of the water treatment plant

As a rule of thumb, the required available site area: A (acres) Q0.6 (mgd)- One large plant vs two or three medium size plants

7. Treatment plant sizeGeographical location, geological information, availability of electric power and utilities, accessability to major highways, history of flooding, construction cost, site maintenance costs, provisions for future plant expansion

8. FinancingRevenue bonds, general obligation bonds, special assessment bonds, state and federal aid funds, etc.

Breakdown of Water Treatment Plant Construction Costs (Approximate)

Civil work (earthwork, grading, paving, fencing) 7.0% Yard pipings 8.0% Landscaping and irrigation 1.0% Operations building (chemical feed system included) 10.0% Flocculation and sedimentation basins 17.0% Filters 20.0% Clearwell 8.0% Pumping facilities 7.0% Meter vaults (L.S.) 2.0% Filter washwaste holding and recycling 3.0% Sludge drying beds 2.0% Miscellaneous items 0.3% Chemical storage facilities 1.0% Electrical and instrumentation works 12.0% Testing and disinfecting works 0.2% Move on and move off (contractors) 1.5%

Notes: (1) The table does not include the overhead and profit of the contractor; these are generally 20% of the total cost shown above.

(2) The above figures are based on a high-rate conventional process. 37

38

Quality and Treatability of Raw Water

Surface water:• Review 5 ~ 10 yrs of physical, chemical, microbiological,

and radiological characteristics of the raw water. • Conduct a risk assessment for potential contamination.• Assess the degree of present and future land development in

the water shed.Groundwater:• Consider the same factors associated with surface water.• Geological conditions, water tables, the drawdown of the

water table due to pumping, seawater intrusion, potential leaching of industrial wastes, domestic wastes, agricultural chemicals, and fertilizers into the groundwater.

39

Objectives for Finished Water Quality

• To provide safe and aesthetically appealing water to consumers without interruption and at a reasonable cost.

• National Interim Primary Drinking Water Regulations (NIPDWR) - set the maximum contaminant levels (MCLs); designed to protect the public health; mandatory compliance

• National Interim Secondary Drinking Water Regulations - Generally related to aesthetic quality of a water supply; recommended goals

- Turbidity was designated as a health-related rather than an aesthetical parameter: forced many treatment facilities to construct filtration facilities

- MCLs for total trihalomethanes (THMs) were proposed

40

Objectives for Finished Water Quality(continued)

1986 Amendment and the National Primary Drinking Water Regulation (NPDWR)

• Filtered water turbidity: 0.3 NTU for 95% of the time• Disinfection: 99.9% of Giardia lamblia cysts and 99.99% of

enteric viruses must be removed• MCLs for disinfection by-products (DBPs)• MCLs for volatile organic compounds (VOCs)• MCLs for synthetic organic compounds (SOCs) (pesticides,

PCBs, acrylamide, epichlorohydria, styrene, etc.) and for inorganic compounds (IOCs) (nitrate, nitrite, asbestos, etc.)

• MCLs for corrosion by-products such as lead (0.015 mg/L) and copper (1.3 mg/L) and pH

41

Water Quality Regulatory Process Interactions.

State agency designatesBENEFICIAL USES

Local agency withdraws water for municipal

supply

Local agency selectstreatment process

to meet federal states

Local agency supplies water meeting enforceable

STANDARDS and its own GOALS

Local agency selects treated water quality

GOAL

Federal agency develops advisory water quality

CRITERIA

Federal state agencies promulgate enforceable

water quality STANDARDS

Based on data and scientific judgment

42

Factors in Setting Water Quality Standards

Health

Political realities

cost

Technical feasibility

43

Additional Goals and Objectives

Water quality goals: contaminant concentrations which a water supplier chooses to achieve in order to ensure it consistently meets regulated levels

• More stringent than standards• Determined based on costs, benefits, and the overall

philosophy or posture of a water supplier• To achieve the goals, the required function of each unit

process (of the treatment process train) must be identified and the objectives of each of these units should be defined.

• Optimize the total plant design.

44

The Current Contaminant Candidate List and Next Steps

Regulatory Determination Priorities 20 contaminants

Research and OccurrencePriorities

40 contaminants

CCLFurther Analysis

Research…On health15 contaminantsOn treatment technologies12 contaminantsOn analytical methods15 contaminants

Occurrence Data Collection34 contaminants

CCL(2005)

9 microbiological contaminants and

42 chemical contaminants or

contaminant groups

RegulateDon’t Regulate

Other (Guidance)

Actions/Next Steps 2001 Decision

45

Restriction and Constrains on Plant Design

• Restrictions:Due to economic, physical, chemical, temporal, climatic, geological, sociological, legal, or aesthetic considerations imposed by local, state, or federal agencies.

• Constrains:due to building codes, zoning laws, OSHA regulations and standards, and limited number of available components, materials, technology and qualified personnel.

46

Treatment Process Selection: Alternatives

• Alternatives:established by the characteristics of the raw water and the finished water quality goals; consider future implementation of more stringent EPA standards, possible changes and variability of the raw water quality, availability of major equipment, postinstallation services, capability of operators and maintenance personnel, waste handling requirements, and availability and cost of chemicals.

• Final Process Selection: based on reliability, constructability, ease of operation, simple maintenance, and cost.

47

Hydraulic Grade Across the Plant

• Important to establish the hydraulic grade line across the plant when selecting the site.

• For conventional water treatment plants, 16 ~ 17 ft of headloss is expected.

• For plants employing preozonation or GAC adsorption processes, 25 ft of headloss is expected.

• The ideal plant site will have a 3 ~ 5% one-way slope.

48

Hydraulic Grade Across the Plant

(continued)

49

Geotechnical Considerations

• Information necessary to design foundations, ground characteristics, soil characteristics.

- Soil pressure

- Data on excavation and fill

- Groundwater level

- Site seismicity

50

Structural Design Conditions and Criteria

• All structures must be capable of withstanding dead weight, live weight, water pressure, earth pressure, forces resulting from earthquake, vibration, wind pressure, ice pressure, etc.

• Min. reinforced concrete wall and slab thickness bearing water 8 in.

• Water/cement ratio 0.5

• Compression strength: min. 4000 psi (280 kg/cm )

• Allowable shrinkage rate: 0.04 - 0.05%

• For soil and groundwater having high sulfate, Type 2 or Type 5 cement may be considered.

51

Plant Waste Handling and Disposal• Recoverable wastes:

filter wash water, supernatant of the sludge drying beds, and plant overflow - commonly collected in a holding tank and recycled to the headwork after treatment (flocculation, sedimentation, and disinfection) - the treated recoverable wastes are allowed to be discharged to a nearby water course.

• Nonrecoverable wastes: sludge from both the clarifiers and the filter wash-waste holding tanks, sanitary and chemical wastes, and wastes produced by sludge press or ion exchanger - commonly discharged into the sewer system - gravity thickening, physical/chemical separation, heat treatment, etc.

52

Instrumentation and Control System

Objectives: to provide

• Continuous production and supply of safe drinking water

• Automatic execution of corrective measures and automatic response

• Minimizing the potential human error

• Capability to quickly solve analytic problems

• Ability to diagnose problems in remotely located equipment before a malfunction occurs

53

Preliminary Cost Estimates

• Used to select the best treatment system among the various water treatment alternatives on the basis of cost effective construction and the costs associated with plant maintenance and operation.

• Common method: use the cost estimation curves developed by the EPA (Estimating Water Treatment Costs, EPA 600/2-79-162b, August 1979).

• May be adjusted to a geographical area in the United States and to current standards through the application of a special cost index. e.g., Engineering News-Record (ENR) Construction Index and Handy-Whitman Index of Water Utility Construction Cost.

• Expected accuracy: +30% to -15%

54

Water Treatment Plant Construction Curves

55

O&M Cost Estimation Curve(Conventional Process with a Good Raw Water Quality)

56

Plant Layout

• Use a computer-aided design and drafting system (CADD)

• Basic plant layout: cluster, satellite or college campus

• Engineering consideration - minimization of civil work costs

- ease of construction - automatic, equal hydraulic loading

to each unit - centralization of control and operation - physical separation of the major unit process structures - master plan development for plant and piping layout - climatic conditions

- architectural design

57

Campus Plant Layout

Campus Layout

58

Campus Plant Layout - continued

Campus Layout

59

Cluster Plant Layout

Chemical &Control Building

Clear Wells

Flo

c/S

edT

anks

Flo

c/S

edT

anks

Fil

ters

Floc/Sed TanksChemical & Control Building

Filters ClearWells

60

Process Diagram

61

Environmental Analysis Report

• Required to file an Environmental Impact Statement (EIS) prior to implementation.

• Must include detailed studies and an analysis of the environmental impact of the facility.

• Requires a team of many specialists (biologists, hydrologist, archaeologists, and economists)

• Should indicate no environmental impact by the proposed project

• Could have tremendous impact on the design, construction schedule, and total cost of the project