FISHBECK, THOMPSON, CARR, & HUBER INC.

Importance of Flow Monitoring February 17, 2015

Lori Lloyd, PE, LEED AP BD+C

Agenda

• Definitions

• Why Flow Monitor?

• Flow Monitoring Applications

• Site Selection

• Lessons Learned

Dry Weather Flow

• DWF – Typical daily flow from the system

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Flo

w (

gp

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City of Niles Meter 3 18-inch DWF

Weekday DWF Weekend DWF

Dry Weather Infiltration

• DWI – groundwater entering the sanitary sewer system through indirect paths like at pipe joints and lateral connections

Wet Weather Flow

• WWF – sewer flows in addition to DWF that occur during a precipitation event

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City of Ecorse Meter 10 - 7/27 Event

Wet Weather Flow Dry Weather Flow Rainfall

Rainfall Derived Inflow/Infiltration

• RDII – stormwater entering the sanitary sewer system through direct and indirect connections like catch basins, down spouts, and pipe joints

Reasons to Flow Monitor

• Measure discharge for billing purposes

• Establish dry weather flow patterns

• Quantify and isolate wet weather flow

Why Flow Monitor?

Credit: Alan Cressler

Why Flow Monitor?

• Sewage overflows

• Basements back ups

• Capacity assurance/ MDEQ compliance

• Transport and treatment costs

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2011 Lift Station Daily Flow

Main Flow Central Flow Total Flow Rainfall

Who Needs to Flow Monitor?

• I/I problem?

MORs/WWTP data and lift station data

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rage

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low

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Meridian Township Monthly Flow

2009 2010 2011 2012

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City of Flint WWTP Flows

WWTP Raw Data Rainfall

One Step in the Process

• I/I study

Flow monitoring

Modeling

Sewer System evaluation study (SSES)

Flow Monitoring Applications

• Flow monitoring – a decision-making tool

Collect data used to model collection system

Establish DWF patterns

Identifying areas with high WWF

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Meter 7 12-inch DWF

Weekday DWF Weekend DWF

Dry Weather Flow Patterns – Diurnal Curve

• Establish diurnal or seasonal flow patterns

Dry Weather Flow Patterns – Casino

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w (

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Saginaw Chippewa Indian Tribe Meter 2 15-inch DWF

Weekday Weekend

Dry Weather Flow Patterns – Industrial

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City of Flint Meter 9 48-inch DWF

Weekday Weekend

DWF Patterns – Seasonal Variations

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City of Lincoln Park Meter 2 - 8/14 Event

Wet Weather Flow Dry Weather Flow Rainfall

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Wet Weather Flow Dry Weather Flow Rainfall

Wet Weather Flow Patterns

Site Selection

• Flow monitoring process

• Installation

• Things to consider

• Ideal site

Types of Flow Monitors

• Area Velocity Measurements

Q = A x V

d

V

Marsh-McBirney Flo Dar Sigma 910

ISCO 2150

ISCO LaserFlow

Flow Monitoring Process

• Monitoring program development Site selection and installation

Data collection and handling

Data analysis

Installation

• Confined space certified personnel needed for installation

• Proper installation provides for accurate measurements and can prevent malfunctions and data loss

Air Monitoring

Site Selection Considerations

• Program objectives

• Physical criteria

• Accessibility

• Security

• Budget

Ideal Site

FM

Ideal

MH

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w (

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Meter 6 - Flow Chart

Raw Data Rainfall

Ideal Site

Less Ideal Site

FM

Less Ideal

MH

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CSO #003 (24-inch) - Flow Chart

Raw Data Rainfall

Less Ideal Site

Site Selection

• Where to install flow monitors?

Monitor all areas contributing to the WWTP or pump station

Monitor areas of suspected high I/I

Ideal Site

• Straight through manhole

• No other incoming sewers or laterals

• Adequate depth and velocity

• Not within the influence of a lift station

• No surcharging

• Easily accessible

• Free of excess grease

or debris

Site Selection Lessons Learned

Site Selection Lessons Learned

• Site hydraulics

• Lift station

• Site access

• Grease/debris

Multiple Incoming pipes

Sensor

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Meter 8 - Flow Chart

Raw Data Rainfall

Ideal Site?

Low Depth

Sensor

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Meter 4 - Flow Chart

Raw Data Rainfall

Low Velocity

Sensor

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Meter 1 – WWTP

Raw Data 2 Rainfall

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Raw Data Rainfall

Lift Station Influence

Lift Station Influence

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Meter 4 - 4/15 Event

Wet Weather Flow Rainfall

Accessibility

Accessibility

Accessibility

Accessibility

Accessibility

Accessibility

Accessibility

Accessibility

Accessibility/Security

Silt Covering Sensor

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Meter 11 - Flow Chart

Raw Data Rainfall

Silt and Seasonal Variation

Grease on Sensor

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Meter 7 - Flow Chart

Ideal Site?

Credit: Bill Lackey

Conclusions

• Know the objectives of your flow monitoring program

• Allow enough budget and time to collect necessary data

• Work closely with field staff when picking sites

• Flow vary greatly between systems and seasons

• Careful site selection can save time and money

FISHBECK, THOMPSON, CARR, & HUBER INC.

Thank You Questions?

Lori Lloyd

LALLOYD@FTCH.COM

616-464-3941