Joint Water Purification Project-Colorado's First Planned Indirect

Potable Reuse

April 25, 2013

Joint Water Purification Project-Colorado's First Planned Indirect

Potable Reuse

April 25, 2013

California WATEREUSE –Central Valley Sierra Foothills

California WATEREUSE –Central Valley Sierra Foothills

Project OverviewProject Overview• Joint venture with two

owners:– Arapahoe County W&WW

Authority (ACWWA)– Cottonwood W&S District

(CWSD)• Location

– Southeast Denver metro area

• System Capacity– Initial= 9 mgd– Build out= 12 mgd

Water Supply SourcesWater Supply Sources

• Sources– Non-renewable deep aquifer sources– Renewable Cherry Creek alluvial water

• The renewable alluvial water has several water quality issues:– High percentage of effluent form upstream

WWTPs– (≈ 60% current, up to ≈ 80% in the future)– Emerging contaminants of concern– Aesthetics (Iron, color, hydrogen sulfide)– Uranium and radon gas

Cherry Creek and a typical alluvial well house

Alluvial / Indirect Potable Reuse Water Quality Issues

Alluvial / Indirect Potable Reuse Water Quality Issues

Water Quality Concerns

Microbial Re-growth

in Wastewater

Project GoalsProject Goals• Original Project Goals:

– Provide treatment for the alluvial water supply, thereby protecting its long term usability

– Long-term implementation of Indirect Potable Reuse to the extent possible

– Provide an appropriate level of treatment that would have public support

– Maximize use of renewable alluvial supply

– Address aesthetic concerns

→ Many of these are policy level decisions

Key Components of the Indirect Potable Reuse System

Key Components of the Indirect Potable Reuse System

• Expansion and upgrades to the Lone Tree Creek Water Reclamation Facility (LTCWRF)

• Development of a Raw Water Delivery system that provided 6 months of travel time

• Development of a water treatment facility and associated waste stream treatment processes

The LTCWRF, which includes tertiary treatment/ filtration, was placed into operation August 2009

Overall System ConfigurationOverall System Configuration

Water Treatment

Brine Treatment

WastewaterTreatment

Alluvial Recharge

Deep Aquifer Wells

Dedicated Alluvial Wells

Dedicated Alluvial Wells

Brine to Discharge

JWPP WTP

Park/ Greenbelt Irrigation

Potable Water Use

Waste Discharges to Sewer

Project TimelineProject Initiation

2003 July2005

Sept2005

Jan 2006

June 2006

Oct2007

Feb 2008

Aug 2009

June2010

JWPP WTP Pre-Design Complete

LTCWRF Pre-Design CompleteLTCWRF Design Complete

LTCWRF Construction Begins

JWPP WTP Design Complete

JWPP WTP Construction Begins

LTCWRF Construction CompleteJWPP Producing Water

Project DevelopmentProject Development• Developed a Technical Advisory

Committee (TAC)• Hired a Public Relations firm to assist

with developing the message• Evaluation & comparison to CA Indirect

Potable Reuse Systems, site visits• Implementation of multiple barrier

concepts• Progress design meetings with Colorado

Dept of Public Health and Environment• Presentations to engineering community• Public participation and presentations• Value Engineering during design

Technical and Institutional IssuesTechnical and Institutional Issues• Development in a high end commercial park• Fouling of RO membranes due to

wastewater colloidal particles• Treatment of RO brine to remove

phosphorus and other permit requirements• Impacts of waste streams to the sewer

system• Accumulation of salts in the alluvium due to

RO brine discharge• Challenges in developing the raw water

system, including yield and locating wells with acceptable water quality for membranes

Significant capital and O&M costs are realized for the RO brine treatment system

Comparison of System Configurations

Comparison of System Configurations

Joint Water Purification Project

AdvancedWater Treatment

Advanced WastewaterTreatment

Alluvial/Aquifer Discharge and Treatment

Advanced WastewaterTreatment

AdvancedWater Treatment

Alluvial/Aquifer Discharge and Treatment

California IPR Systems

ACWWA/CWSD have little control over other WW discharges and urban runoff

Customers

Customers

Potable Treatment ConfigurationPotable Treatment ConfigurationWater Quality Monitoring RO Skids Oxidation

Reactors (UV/H2O2)

Air Strippers

Clearwell/

DisinfectionAlluvial Filtration/ 6 month Travel Time

Advanced Wastewater Treatment

Plant Multiple Barrier ConceptsPlant Multiple Barrier Concepts

1. Will generally remove organics except volatiles with MW < 200-3002. Will remove radionuclides with the exception of radon gas3. Will remove light volatile organics4. Will remove radon gas only

TREATMENTPROCESS

CONTAMINANTS OF CONCERN

Pathogens/Microbial

Inorganic Radionuclides Organics

TOC VOC/SOC Emerging

Alluvial Filtration

X1 X1 X1 X1

ReverseOsmosis

X X X2 X X3 X3

Advanced Oxidation

X X

Air Strippers X4 X5

Chemical Disinfection

X

Construction Cost SummaryConstruction Cost SummaryITEM COST

Bid Package 1-Water Treatment Plant

$27,500,000

Potable Treatment Processes $23,000,000

Concentrate Treatment System $4,500,000

Bid Package 2-Pipelines

$3,500,000

Bid Package 3-Raw Water Supply Wells

$2,000,000

TOTAL $33,000,000

Questions and AnswerQuestions and Answer