Exploring Regional Water System Interconnections in the Triangle

95TH Annual Conference | November 2015 | Raleigh Convention Center, Raleigh, NC

Jeff Cruickshank, Hazen and Sawyer Steve Brown, Town of Cary

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Presentation Outline

Project Background

Technical Aspects

Modeling Examples

Conclusions

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• Interlocal effort begun in 2009 to coordinate planning and further development of the regional water supply to meet future needs

• Local government led initiative – demonstrate that local leadership can solve regional water planning challenges

What is the Jordan Lake Partnership?

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Long term sustainable and secure regional water supply for the

Research Triangle area.

Purpose of the Partnership

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Apex

Cary

Chatham County

Durham

Hillsborough

Holly Springs

Morrisville

Orange County

OWASA

Pittsboro

Raleigh

Sanford

Wake County

Who are the Partners?

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Water Service Areas

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Water System Connections

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• A secure, sustainable water supply for the region

• Promote water conservation and efficiency

• Model cooperation and communication

• Provide a forum to address mutual interests and work through challenges

• Ensure regional/basin-wide ability to meet long term water supply needs

The Partnership does not…• Make ANY policy decisions

What are the Goals?

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Partnership Next Steps

• Plan future infrastructure investments

• Western Intake, treatment and transmission facilities

• Regional interconnections

• Broaden focus of regional collaboration

• Emergency response planning

• Water efficiency education

• Water shortage indicators

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JLP Interconnection Project: Phase 1

Mapped all 42 interconnections for the first time

Used GIS for pressure-zone level of detail

Tabulated key information about each system:

• production capacity

• demand

• tank overflows and volume

Described each system’s:

• facilities

• vulnerabilities

• limitations

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Phase 1 Map

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Phase 2: Interconnection ModelingScope and Approach

Began by compiling laundry list of modeling requests

Consolidated requests into 13 modeling projects

Specified two-way transfers for all projects

Considered sustainable flows for long durations

Outlined an incremental approach for building combined model to provide info as project progressed

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Phase 2 Approach: Identify Limitations

Pressure Zone Pumps or PRVs

Pipe Capacity

Supplying System

Interconnect

Receiving

System

Control Valve or Pumps

Production Capacity

Interconnect

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Modeling Approach:Extended Period Simulations

Steady state not good enough for sustainability and full impacts

Extended period simulations check pumps & tanks over time

Multiple connections analyzed simultaneously – interactions

Steady State EPS

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Model Demands Agreed Upon by JLP

5-month summer average for supplying systems

Maximum week in receiving systems

Diurnal patterns applied to demands in each system

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10 Modeling Projects in Phase 2 Scope

Each provides information requested by Partners

All determine limitations on sustainable flows with current infrastructure

Most include testing improvements to increase transfer capacity to achieve specified targets

Nearly all involve two-way transfers

Projects ordered to build combined model incrementally

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Hydraulic Model Status for Phase 2Partner Model

?Demands Updated

InfrastructureUpdated

LastCalibration

SoftwareUsed

Apex Yes 2005 2005 2005 WaterCAD

Cary Yes 2008 2008 2008 InfoWorks

Chatham County Yes 2011 2011 2013 WaterGems

Durham Yes 2008 2014 2008 WaterGems

Hillsborough Yes 2002 2013 2013 WaterMax

Holly Springs Yes 2012 2012 2012 InfoWater

Morrisville Included in Cary

Orange County No N/A N/A N/A N/A

OWASA Yes 2011 2011 2011 WaterCAD

Pittsboro Yes 2010 2010 200 WaterCAD

Raleigh Yes 2014 2014 2014 InfoWater

Sanford Yes 2007 2007 2007 InfoWorks

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Technical Challenges

Maintaining unique IDs for model elements

Designating active pipes to model 2016 conditions

Debugging vestiges of model conversions - units

Adding interconnection details

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Project 1: Convert and CombineModels of Cary and Durham

• Converted InfoWorks and WaterGEMS models to EPANET and imported into new InfoWater model

• 39,000 pipes

• 5 modeling tasks

Durham

Cary

Main Zone(568)

SE HighZone(615)

WesternPressure

Zone(540)

CentralPressure

Zone(641)

SouthernPressure Zone

(595)

High Zone(700)

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57,000 pipes

8 modeling tasks

OWASA

Durham

Cary

Main Zone(568)

SE HighZone(615)

640 Zone

CentralPressure

Zone(641) Southern

Pressure Zone(595)

High Zone(700)

740 Zone

WesternPressure

Zone(540)

Project 2: Add OWASA

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Project 3: Add Hillsborough

58,500 pipes

3 modeling tasks

OWASA

Durham

CaryMain Zone

(568)

SE HighZone(615)

Central Zone(737)

High Zone(700)

North Zone(814)

South Zone(832)

Hillsborough

Closed valves between

Hillsborough and OWASA

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Project 4: Add Apex and Holly Springs

63,000 pipes

3 modeling tasks

Hillsborough

Durham

OWASA

Cary

Apex

Holly Springs

814

737

832

740

640

700

568

615

540

641

595

616

585

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ChathamNorth

ChathamAshburyChatham

Southwest

Hillsborough

OWASA

Durham

Cary

Apex

Holly Springs

Chatham County

US 64

Project 5: Add Chatham County

65,000 pipes

2 modeling tasks

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Project 6: Add Raleigh

137,000 pipes

120 mgd demand

8 WTPs

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Example Project: Move Water Between Cary and OWASA Through Durham

642 568

540 641

615568

641

642

540

615

From Cary to OWASA From OWASA to Cary

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Identifying Pipes Limiting TransfersHead Loss in 2-foot increments

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5.9 mgd Sustainable Flow from OWASA through Durham to Cary & Apex

5.74 mgdBy gravity

4.2 mgd by gravity at I-40 meter

616 ZoneApex

5.74 mgdMax Week

641 Zone

Cary26.2 mgdMax Week

540 Zone

3.1 mgdDavis BPS

2.8 mgdIntermittent

NC 55 BPS

1.7 mgd by gravity at NC 54 meter

Durham28.9 mgdMax 5-mo

568 Zone

Jones Ferry WTP

13.7 mgd

28.9 mgd Durham WTPs

OWASA6.83 mgdMax 5-mo

640 Zone

26.0 mgd Cary/Apex WTP

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Pressures Changes with Flow fromOWASA through Durham to Cary & Apex

In OWASA

• 27 psi max drop near Durham

In Durham

• 10 psi max rise near OWASA

• 22 psi max drop near Cary

In Cary

• 16 psi max rise near DurhamPressure Change

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Predicted Tank Performance Shows Transferred Flows are Sustainable

Red: OWASA Green: Cary Blue: Durham

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Interconnection Modeling Summary

Bridged the gap between thinking about interconnection transfers to seeing how they work

Explored and quantified sustainable flows

Tested interconnections without affecting costumers

Developed operating procedures – no surprises

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Potential Benefit: Reduce Water Supply Costs By Sharing Surplus Capacity

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AWWA Supports Regional Approaches

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Acknowledgements

Jordan Lake Partnership:

Steve Brown, Co-author

Sydney Miller, Project Manager

Hazen Modeling Team:

Jinggy Espinosa

Todd Davis

Kevin Widderich

Wayne Zhang