Flow Monitoring Data Analysis

Prepared By Thomas Romza E.I.

Overview • Data Management

– Calibration – Editing

• Flow Analysis – Dry-weather – Wet-weather – Conclusions

• Model Inputs

Data Management

• Goal: Accurate Flow Data

• Bad Raw + Bad Cals = Bad Data • Bad Raw + Good Cals = OK Data • Good Raw + Good Cals = GREAT Data

Raw Data Calibrations

Final Processed

Data

Installation, Calibration, Operation, and Maintenance

• Calibration Is Important to Ensure Meter Reads Accurately – Flow is calculated from the meter

readings of depth (converted into flow area) and velocity

– If meter isn’t accurate in either parameter the flow can be falsely high or low

• Flow Meters Are “AV” (Area-Velocity) Meters – Q = Flow = A x V

D

A V

Q

Data Management

D

Data Management

• Raw Data - Depth – Inaccuracies in the meter – Drifting readings

Flow

Velocity

Ultra

Pressure

Data Management

• Depth Importance – 10” pipe @ 2 fps

Q = 0.14 mgd Q = 0.18 mgd

.5” depth difference

≈ 25% FLOW DIFFERENCE

D = 2.5 in A = 15.4 in2

D = 3 in A = 19.8 in2

Data Management

• Raw Data - Velocity – Peak Velocity vs. Average Velocity

2.0

1.6

1.4

1.2

1.0

Peak = 2.0 Average = 1.7 Factor = 0.85

Peak = 1.2 Average = 1.1 Factor = 0.86

1.8

Data Management

• Velocity Importance – 10” pipe @ 3 in depth

V = 1.5 fps V = 1.8 fps

Q = 0.13 mgd

A = 19.8 in2 .3 fps velocity difference

≈ 20% FLOW DIFFERENCE

Q = 0.16 mgd

A = 19.8 in2

Data Management

~At least 4-5 throughout the duration of the metering period!

Multi-point Profile

Depth Velocity Profile

Data Management

Depth Correction (+0.5”)

Field Offset (-0.5”)

Raw

Final

Data Management

Raw

Data Management

Peak Flow (unadjusted)

Peak Flow (adjusted)

1.5 MGD – 30% Reduction of Project Scale

Installation, Calibration, Operation, and Maintenance

• WHY??? – Raw Meter Data

Inaccurate Flow Inaccurate DW Baseline Inaccurate WW Results Inaccurate Model Inputs Inaccurate RECOMMENDATIONS

Inaccurate Flow – Detrimental to post rehab monitoring

Data Management

Flow Analysis • Trying to Find Correlation Between Rain and Flow • Dry-Weather Flow Analysis (DWF)

– Important to have a span of days without rain so that the water table settles

– Baseline Flow

for the rest of analysis

– Diurnal Curves

Flow Analysis – Diurnal Curve

Diurnal Low Flow “Trough” Flow ~ 0.8 mgd

Average Dry Weather Flow ~ 1.4 mgd

Diurnal Peak Flow ~ 1.8 mgd

Flow Analysis - DWF • Diurnal Variations Can Yield Conclusions about the System

– Low diurnal peaking factor (1.8 Peak to 1.4 Ave ~ 1.3 PF) – High trough to ADWF percentage (.8 trough to 1.4 Ave ~ 57%)

Manhole Joints

Pipe Seals Mainline

Joints

Break-in Taps

Lateral Joints

Manhole Cracks

Mainline Cracks

Lateral Cracks

Discrete ADWF

Estimated Population

Average Flow (Typical 70 gal)

(mgd) (census (gal/capita/day)WHL-01 0.299 3900 77 Residential

WHL-02 + 02A 0.170 2587 66 ResidentialWHL-03 0.173 1120 155 50% BusinessesWHL-04 0.438 3332 131 50% BusinessWHL-05 0.255 2472 103 Middle SchoolWHL-06 0.190 1013 188 25% BusinessWHL-07 0.245 2380 103 40% BusinessWHL-08 0.073 256 287 75% BusinessWHL-09 0.244 3414 72 ResidentialWHL-10 0.316 4852 65 Residential

WHL-10A 3.183 N/A N/A N/AWHL-11 0.697 3814 183 High School

WHL-11A** 0.003 0 N/A Overflow MeterWHL-12 0.467 239 1956 100% BusinessWHL-13 0.065 2671 24 Multi Family UnitsWHL-14 0.134 2978 45 ResidentialWHL-15 0.239 1249 191 67% BusinessWHL-16 0.184 118 1560 100% Airport/BusinessWHL-17 0.190 1090 175 75% Business

Basin Basin Characteristics

Flow Analysis - DWF

• Population Equivalent – Census Data – Generally about 70

gal/capita/day – High flow/capita

means: • Non-residential area • OR high ground water

infiltration

Flow Analysis - DWF

• Unique Situations – Flow Diversions – Lift Stations – Snow Melt – Swimming Pools Draining – Sporting Events – Holidays – Black Friday @ Woodfield

Installation, Calibration, Operation, and Maintenance

• WHY??? – Raw Meter Data – Accurate Flow

Inaccurate DW Baseline Inaccurate WW Results Inaccurate Model Inputs Inaccurate RECOMMENDATIONS

Inaccurate Baseline – Dampen or exaggerate peaking factors from wet-weather flow

DWF Analysis

Flow Analysis - Rain

• Rain Data Analysis

Flow Analysis - Rain • Rain Data Weighting

– Inverse Squared Distance method

– Apportion rain to basins according to distance from rain gauge to basin centroid

43% RG-01 57% RG-02

12% RG-01 88% RG-02

82% RG-01 18% RG-02

88% RG-01 12% RG-02

Flow Analysis - WWF

• Wet-Weather Analysis – Rain Derived Infiltration and Inflow (RDII)

Flow Analysis - WWF

• Wet-Weather Analysis – Excess Flow vs. Rain

• Predict for larger rain events

– Peaking Factors • Excess Flow vs.

DWF • Predict for larger

rain events

Observed PF of ~ 3.0

Flow Analysis - WWF • Downstream Control and Capacity Issues

– Hydrographs • Increase in depth and decrease in velocity • Constant/decreasing flow

Downstream Control

Max Flow of ~2.75 MGD

Flow Analysis - WWF • Downstream Control and Capacity Issues

– Scattergraphs • Mannings Curve • Iso-Q lines`

Manning’s Curve

ISO-Q Lines

Installation, Calibration, Operation, and Maintenance

• WHY??? – Raw Meter Data – Accurate Flow – Accurate DW Baseline

Inaccurate WW Results Inaccurate Model Inputs Inaccurate RECOMMENDATIONS

Inaccurate WW Results – Incorrect priority basins and quantification. Focus on the wrong areas.

WWF Analysis

Flow Analysis – Model Inputs/RTK Analysis • RTK Method Is an Empirical Way to Duplicate Collected

Flow Data with Inputs and Constants • Model Input

What Is RTK? • Not an Acronym • Unit Hydrograph (UH) method to represent the

relationship between rain and flow • Atomizes rainfall-derived infiltration and inflow (RDII)

response into UH described by R, T, and K • Reconstitutes UH into model by applying a rainfall

distribution to UH

What Is RTK? • R = Percent Rainfall

Capture

• T = Time to Peak

• K = Receding Limb Multiplier

R-Component

T-Component K-Component

(K × T)

RTK Unit Hydrographs

• 3 Components of RDII: – Fast (1) – Medium (2) – Slow (3)

RTK Analysis

RTK Analysis Applied to a Rainfall Distribution

RTK Analysis Application

Over-prediction due to DS control

Installation, Calibration, Operation, and Maintenance

• WHY??? – Raw Meter Data – Accurate Flow – Accurate DW Baseline – Accurate WW Results

Inaccurate Model Inputs Inaccurate RECOMMENDATIONS

Inaccurate RTK Storage Calculation Wet-weather extremes in the model

Model Inputs and RTK Analysis

• Data Handling – Accurate flow data from depth

and Velocity

• DWF Analysis – Baseline Flow – ADWF factors – Trough % and

Diurnal Peak

• WWF Analysis – Correlations between rain and

excess flow – Peaking Factors – Infiltration vs. Inflow – Downstream Control and

capacity issues

• RTK Parameters

Flow Analysis Summary

Flow Analysis Results

• Recommendations – DWF - Is there need for base flow reduction?

• High Infiltration? – Diurnal PF and Trough % – High flow per capita

– WWF – Is there need for capacity improvements, storage, or I/I reduction? • Basin Peaking Factors • Capacity of sewers

– Downstream Control

• Model Inputs – DWF

• ADWF and Diurnal Variation – WWF

• Basin Size and RTK Parameters

Installation, Calibration, Operation, and Maintenance

• WHY??? – Raw Meter Data – Accurate Flow – Accurate Baseline – Accurate Results – Accurate Model Inputs

ACCURATE Recommendations

FLOW DATA MANAGEMENT & ANALYSIS

Questions?