© 2014 HDR Architecture, Inc., all rights reserved. © 2014 HDR, Inc., all rights reserved.

Addressing Cary’s Long-Term Water Supply Needs CARY/APEX RAW WATER PUMPING STATION IMPROVEMENTS

DESCRIPTION OF EXISTING FACILITIES PROJECT DESIGN GOALS AND OBJECTIVES EVALUATION AND RECOMMENDATIONS DESIGN/CONSTRUCTION CHALLENGES

(Four) 54” Diameter Intake Screens (Four) 250 HP Pumps And (Three) 500 HP Pumps 30” And 42” Transmission Mains Low Density Voltage <600V Bag Fed PAC System 2 Generators (600KW And 1200 KW) Customers – Town Of Cary, Town Of Morrisville, RDU, Southern And Western Wake County, Portion Of RTP, Town Of Apex EXISTING FACILITIES

Capacity Limitations Intake (47 MGD) Based On NC WRC 0.5 FPS Intake Through-Slot Velocity Requirement RWPS (41.5 MGD) Based On Firm Capacity Transmission Mains (23 MGD) Based On Loss Of 42” Main Phase 3: 62 MGD Build-Out: 75.5 MGD ANALYSIS Condition Build- Out Total Peak Day Demand (mgd) Chatham Raw Water Demand (mgd) Plant Losses (10%) (mgd) Total Peak Raw Water Demand (mgd)

Several Modeling Iterations Were Performed To Determine: Expansion Capacity Necessary To Meet Projected Water Demand Systems And Processes Needed To Comply With Existing And Potential Future SDWA Regulations Improvements Needed To Increase Reliability Of Intake, Raw Water Pumping Station, And Raw Water Transmission System GOALS

(Seven) 800 HP Pumps Upsize To Medium Density Voltage To Meet Pumping Capacity Of 62 MGD (Three) 4160 VAC Emergency Generators Third Transmission Main, 42/48”, And Interconnections Increase PAC And NaMnO 4 Storage And Feeding Capabilities To Provide Taste And Odor Control As Well As Manganese Oxidation Service Building Addition PROPOSED IMPROVEMENTS

42/48” Transmission Main To Provide: Additional Flow Capacity Redundancy To 42” Main. 30” Main Has 23 MGD Capacity Redundancy To 54” Main At WTF. Loss Of 54” Main Would Result In Complete Water Loss RESILIENCY AND REDUNDANCY

Water Treatment Facility Expansion Rapid Mix Tank And Mixer Expansion Ozone Generator Pre-Ozone Contactors Intermediate Ozone Contactor Conversion Closed Loop Cooling System For Ozone System Media Filters (4) Superpulsators® (2) Chemical Feed Expansion/Improvements Administration/Lab Building Expansion Dewatering Polymer And Centrifuge Expansion Generator Expansion High Service Pump Addition RESILIENCY AND REDUNDANCY

Challenges Poor Soil Conditions Limited As-built Information Working Around an Existing Operating System Construction Sequencing PAC System Construction Changes CONSTRUCTION

Poor Subgrade/Backfill POOR SOIL CONDITIONS Rock

Raw Water Intake Structure and Piping Airburst Piping Location Search Disturbed Lake Bed, Released CO2, Inadvertently Impacted SuperP’s® Divers Created As-Built Dwgs Wetwell Required Vortex Basket Changes Surge Tank Piping LIMITED AS-BUILT INFORMATION

MOPO Main Goal: Maintenance Of Plant Operations Water Supply Must Be Guaranteed Result – Around The Clock Construction Low Demand Period (28 MGD) WORKING AROUND AN EXISTING OPERATING SYSTEM

Pipe Modifications Subaqueous Work Switching Between Northern and Southern Mains Electrical Upgrades Coordination With Duke Energy Tying-In Medium Density Voltage Medium Voltage Service Area Decrease CONSTRUCTION SEQUENCING

Considerations Made During Construction Increased Storage To Aid In Raw Water Treatment Historic Taste and Odor Events During Construction Weather And Lake Effects PAC SYSTEM CONSTRUCTION

Questions?

Contract Amount $16,673,000 Schedule NTP: May 19, 2014 Substantial Completion: October 16, 2015 Final Completion Date: November 15, 2015 CONSTRUCTION