Aurora’s Prairie Waters Project – A Sustainable and Innovative Water Supply Solution

Colorado State UniversitySeptember 17, 2007

Mark Pifher/Aurora Water

Presentation Outline

• Background and Need

• Project Alternatives & Integrated Resource Planning

• Selected Alternative– Prairie Water Project Overview

– PWP Key Components

– Purification Strategies

• Cost Estimates

Colorado River

Arkansas River

South Platte River

A Water Supply Crisis for Aurora Storage Capacity vs. Total Storage

20000

40000

60000

80000

100000

120000

140000

160000

Year

Acre

-feet

Storage Capacity

26% of Annual Demands in Storage

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2005 2010 2015 2020 2025 2030 2035 2040 2045 2050

Syst

em Y

ield

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m D

eman

d (1

000's

acr

e-fee

t/yea

r)

Today's SystemPrairie Waters Project - Core ProjectPrairie Waters Project (with Future Additions)

55,500 AF/YR

65,500 AF/YR

105,500 AF/YR

`

Prairie Waters Project Provides Drought Hardening and Meets Long-Term Capacity Needs

Aurora Conducted Comprehensive Integrated Resource Planning

• 50 potential projects

• Range of individual project yields: – 2,000 to 48,000 acre-feet / year

• Basins of Origin:– Colorado River

– Arkansas River

– South Platte River

• Demand Management Included with Water Supply Forecasts

Integrated Resource Plan Considered Key Criteria in Evaluation of Water

Supply Options

• Capital/Operating Cost• Institutional/Government/Public Issues• Environmental/Permitting Issues• Sustainability• Expandability• Yield• Schedule Risk

Institutional Hurdles

A. Federal permits/approvals (e.g., 404, section 7)

B. Federal facilities (e.g., Bureau of Reclamation)

C. NEPA reviews

D. Local permitting (e.g., land use regulations)

E. Local politics (e.g., ag to urban transfers, transbasin diversions)

F. Public perception

G. HB 1177 Roundtable Process

Regulatory Issues

A. SDWA Requirements

1. MCLs

2. SWAP

3. Treatment Requirements (WQCD)

4. TDS Levels (Citizens)

B. DFlows and Discharge Permits

C. “New” Water Quality Standards (includes temperature and emerging contaminants)

Regulatory Issues

D. “New” Aquatic Life Tiers

E. R/O Brine Disposal

F. 404 Permit and 401 certification

G. ESA Issues (flows, mice, prairie dogs, eagles)

H. South Platte TMDL Efforts

Aurora’s Prairie Waters Project

Aurora’s New Water Supply Project

34 miles of 60-inch pipeline34 miles of 60-inch pipeline 3 pumping stations3 pumping stations North Campus (bank filtration and aquifer recharge and recovery)North Campus (bank filtration and aquifer recharge and recovery) 50-mgd water purification facility50-mgd water purification facility

Water Quality Considerations for Prairie Waters Project (PWP) Supply

Pathogens Micro-pollutants

Endocrine Disrupting Compounds and Persistent Pharmaceuticals N- nitrosodimethylamine (NDMA)

TDS Total Organic Carbon (TOC) Nitrate Phosphorus

Comparison of Quality of Aurora’s Water Supplies

Key Water Quality Parameter Rampart Reservoir South Platte (average values)

Phosphorus (mg/L) 0.015 1.4

Ammonia (mg/L) 0.14 2.6

Nitrate (mg/L) 0.05 4.7

Biochemical Oxygen Demand (BOD) (mg/L) <2 11.7

Dissolved Organic Carbon (DOC) (mg/L) <2 8.3

Fecal Coliform (colonies/1000 ml.) 8 198

E coli (Colonies/100 ml.) <10 109

Total Dissolved Solids (TDS, mg/l) 150 to 200 400 to 800

Turbidity (NTU) 0.5 - 8 4-30

Cryptosporidium and Giardia (cysts/ml.) Low Risk (BIN 1) Higher Risk (BIN 2 or 3)

Aurora Water Quality Goals

Nitrate < 2 mg/L

TDS < 400 mg/L

Hardness < 150 mg/L

TOC < 4 mg/L

DBP concentrations no more than current supply

NDMA < 10 ng/L

Reduce concentration of micro-pollutants and pharmaceuticals

Use a natural purification systems as initial purification step

SPP’s purification systems supported by Colorado’s experts

Dr. Ken Carlson

Dr. Jörg Drewes

Dr. Gary Amy

Combining the Best of Natural and Engineered Purification Steps

Challenges

Softening

Taste and Odor

Color

TDS

Nitrate

Pathogens

Organics

Micro-Pollutants

Prairie Waters ProjectNatural Purification Systems

Riverbank Filtration (RBF) (10 days travel time) Aquifer Recharge & Recovery (ARR)

(30 days travel time)

Riverbank Filtration (RBF) Field Testing

• Travel time – approx 10 to 15 days

• Water quality testing

– TOC, turbidity, nutrients (e.g., nitrogen, phosphate)

– Organic micropollutants• Pharmaceutical

• Personal care products and other trace

• Endocrine Disrupters

• Emerging contaminants

0 m 100 m

Aquifer Recharge and Recovery Testing

Feedwater from RBF site

25 Monitoring wells

3 nested piezometer wells

4 production wells

Water quality testing:

• Bulk parameters (TOC, pH, conductivity, nitrate, ammonia)

• Organic micropollutants

RBF and ARR are reliable sustainable/natural purification processes

Nitrate reduced to < 2 mg/L in RBF with 10 days of travel time

Many trace organics and pharmaceuticals are removed (>80%) through RBF and ARR

Phosphorus removal will require amendments to ARR to adsorb phosphorus

Some persistent organics (flame retardants) are not well removed though biodegradation

NDMA removal is significant at travel times > 20 days

RBF Field Monitoring - TOC

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Consistent Removal of Nitrate Through Denitrification in RBF

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RBF/ARR Combination Removal of Selected Pharmaceuticals

Amendments to ARR to Reduce Phosphorus

Prairie Waters Project Cost Estimates

 Estimated Project

CostsEncumbrances as

of 3/13/2007

Core Project  

Storm Drain Bypass                                  $2,200,000  $2,245,119

Pumping Stations 1, 2 and 3                         $57,800,000

Aurora Reservoir Water Purification Facility (inc. UV Equip) $224,000,000 $14,366,802

Conveyance Pipeline Segment 1                       $75,900,000

Conveyance Pipeline Segment 2                       $62,300,000

Conveyance Pipeline Segment 3                       $41,300,000

North Campus                     $68,100,000

Access Road for ARWPF                               $4,800,000 $4,796,000

Zone 4 Tanks/ Zone 5 Pumping Station $13,000,000

OCIP, Control System, System Security $12,900,000 $5,350,474

Subtotal – Core Project Facilities $562,300,000 $26,758,395

Engineering, Program Management, Construction Management, Legal $143,500,000 $79,413,286

Land Costs – Core Project $49,000,000 $27,653,374

Total Core Project Costs $754,800,000 $133,825,055

Why is this the right project for Aurora and Colorado?

Responsible Use of Resources– Reduces the need for trans-basin diversions from Western Slope – Maximizing use of an in-basin renewable resource – Uses water rights already owned by the City of Aurora

River Water Quality Benefits– Minimizes need for a waste discharges such as brine from (RO) – Uses natural treatment systems

Environmental Benefits– Avoids the impacts to wilderness landscapes– Maintains rural open space and river corridor habitat

Protects Public Health– Improves reliability of Aurora’s purification processes – Can address changes in water quality– Exceeds current regulations and meets Aurora’s high standards– Can respond to changes in water quality

Cost Effective and Practical– Reduces cost of purification– Maximizes use of $300 million in water rights already owned by the city

Project Supporters: Environmentalists, Farmers, Businesses, Water Quality Experts

Questions?