Pumping Downhill Can Be A

Good Solution

Hydraulic Transient Analysis Case Study

City Of Indianapolis, IN

Unique Challenges To

Pumping Downhill

March 20, 2012

Randy Vanderwerf, P.E., Clark Dietz, Inc.

Omkar Ghavi, E.I., Clark Dietz, Inc.

Belmont North Service Area

Belmont North

Interceptor (BNI)

BNI System

• Separate Sanitary Sewer System

Sewers 27 inch to 54 inch

• Limited Interceptor Capacity

• Wet Weather Sanitary Sewer Overflows

• Separate Relief Interceptor

• Eliminate Wet Weather Capacity Limit

20-year Build-out of Service Area

BNRI Advanced Facility Plan

50 ft Drop

~ 25 ft

~ 40 ft

BNRI Advanced Facility Plan

• Population Projection

• Rainfall Pattern

Flow Reduction

• Constructability

• Environmental Impacts

Alternative Routes

• Construction Costs

• Present Worth

Project Costs

Value Engineering

BNRI Advanced Facility Plan

780

760

740

720

700

680

Peak Hour … 38 MGD

Daily Average … 7 MGD

Daily Minimum … 3 MGD

Pumps

3 Operating

1 Standby

Belmont North Lift Station Flows

Belmont

North Lift

Station

BNRI Force Main Profile

50 ft Drop

Standpipe

Force Main

Static HGL

745.00

Steady State HGL at 38 MGD

735.00

Air

Pockets

Belmont

North Lift

Station

Standpipe

BNRI Force Main

Force Main Present Worth Analysis

42” Force Main

Pump Cost

Electrical

Cost

Ferric Chloride

Cost

BNRI Advanced Facility Plan

• Project Cost: $222 Million

• Lift Station & Force Main

Savings

$ 49 Million

Belmont

North Lift

Station

Standpipe

42”

42”

42”

42”

Criteria

• TDH > 50 ft

• Flow > 500 GPM

• Pipe > 1,000 ft

• High Points

• Profile: ‘Knees’

BNRI Conditions

• TDH ~ 116 ft

• Flow = 26,200 GPM

• Force Main ~ 28,350 ft

• Valleys and Peaks

• Knee at ~ 15,000 ft

Surge Analysis: Criteria

✓ ✓ ✓ ✓ ✓

Investigate

Hydraulic

Transients

• Valve Movement : Opening / Closing

• Starting or Stopping Pump(s) with

Other Pump(s) Operating

• Change in Flow Demand

• Frequent Variation in Water Level

• Pump Trip due to Power Failure

Typical Causes

Impacts of Transients

• High Pressure

Failure Pumps, Valves

Pipe Rupture

Disintegration of Pipe Lining

Pipe Leaks

• Low Pressure

Cavitation and Column Separation

Collapsing of Pipe

Intrusion of Contaminants

Vapor Cavities: Very High Pressures

Surge Analysis: Importance

• Select & Design Pipe to Withstand

Pressures

• Select Appropriate Check Valves

• Surge Control Devices

Alleviate Adverse Transient Effects

Proper Selection and Location

Start-up / Shutdown Procedures

Surge Control Devices

Active Devices

Modify Conditions by

Providing Liquid or Air to Piping System

Surge Tank

Passive Devices

Limit Extent of High or

Low Pressure

Air Release Valves

Surge Control Devices

Surge Tanks

• Normally Located at Lift Station

Protection against Pump Power Loss

• Pressurized Vessels (Air + Water)

• Supply Liquid to Pipeline

Must Not Empty / Allow Air to Enter

• Initial Air Quantity: Large

Limit Rate of Pressure Drop

Surge Model Layout

Surge Analysis Model

Peak Flow at 38 MGD • Steady State

• Pump Trip: 100% to 0% in 4 seconds

• Monitor Pressures for 320 seconds

Belmont

North Lift

Station

760

780

800

820

840

740

720

700

Standpipe

1600

1400

1200

1000

800

Surge Analysis at 38 MGD

Pressure Envelope

Force Main

Steady State HGL at 38 MGD

HGL after 16 seconds

Very High

Positive Head Several

Times Steady

State

Pressure

Negative Head

Elevation

Steady State Force Main

Steady State HGL at 38 MGD No Surge

Protection

• Max. Pressure 183 psi

• Min. Pressure -14.4 psi

• Conditions Full Vacuum

• Location Everywhere

• Duration 320 sec

Important ARV Features

• Avoid Rapid Air Expulsion

Secondary Surges

Two / Three Stages: Restrict Air Release

Proprietary Designs:

Surge Check Valves

Bias Mechanisms

Throttling Devices

• Sealing Pressure < Static Head

Valve Doesn’t Seal: Discharge Sewage

ARV Selection

Air Valve Considerations

• Non-slam Feature

• Sealing Pressure

• Materials

• Cost

Belmont

North Lift

Station

Standpipe

Force Main

Steady State HGL at 38 MGD

Air Valve

Static HGL

ARV Sealing Pressure Criteria

Force Main

Steady State HGL at 38 MGD

Air Valve

Static HGL

Belmont

North Lift

Station

Standpipe

Valve Sealing Head

Surge Analysis Model: Modifications

700

720

740

760

780

800

820

840

Surge Analysis at 38 MGD

Pressure Envelope

Force Main

Steady State HGL at 38 MGD HGL after 16 seconds

1600

1400

1200

1000

800

Surge Conditions with

No Protection

Air Valves

• Max. Pressure 55 psi

• Min. Pressure -14.4 psi

• Conditions Partial Vacuum

• Location Several

• Duration 320 sec

Surge Tanks: Sewage Applications

Hydro-pneumatic Tank

• Air Compressor: Control Gas Volume

Bladder Tank

• Pre-charged Pressurized Bladder

Hybrid Tank

• Air Vent: Utilize Atmospheric Air

Surge Tanks: Sewage Applications

Hybrid Tank

Courtesy: Charlatte America

Cost

O&M

Issues

Effectiveness

Sewage Surge Tanks Evaluation

Hydro-

Pneumatic

Bladder Hybrid

✓ ✓ ✗

✓ ✓ ✓

820

840

800

780

760

740

720

700

Surge Analysis at 38 MGD

Pressure Envelope

Force Main

Steady State HGL at 38 MGD HGL after 16 seconds

Air Valves &

Hybrid Tank

• Max. Pressure 52 psi

• Min. Pressure -12 psi

• Conditions Partial Vacuum

• Location One

• Duration <0.1sec

PCCP

Force Main

Installation: Standpipe

Installation: Lift Station

Acknowledgements

• Citizens Water, City of Indianapolis

• Dr. Don Wood, KYPipe

• Gwen Phalempin, Charlatte Of America

• Frank Smith, Pipe Tech, Inc.

• Naftali Zloczower, A.R.I. Valves

• Garren Amdur, Vent-O-Mat Valves

• Larry Beynart, Pulsco