South Platte Well Field Aquifer Recharge and

Recovery (ARR) Facility

Walker Reservoir Pump Station No. 1

34 miles of 60-inch

pipeline

Peter D. Binney Water

Purification Facility

Aurora Reservoir

South Platte River

Denver Metro WWTP

Brighton Ditch

Low Permeability Barrier

PWP Well Field (partial)

N

Recharge Basin

Recharge Basin

Water Rights

for the Prairie

Waters Project

Case No. 02CW330 (Pending)

Everist Reservoir 6,000 acre-feet

100 cfs Filling Rights from South Platte River

150 cfs Filling Rights from Lupton Bottom Ditch

For storage of augmentation replacement water

Case No. 06CW104

49 Alluvial Wells: Total Cap: 77.4 cfs (50 mgd)

Augmentation Plan to replace depletions to

South Platte From well pumping

ARR A Underground Storage: 1,180 acre-feet

Surface Storage Right: 9,500 acre-feet

Various exchanges to well field, Brantner Ditch,

Brighton Ditch, and Lupton Bottom Ditch

Case Nos. 97CW272 and 97CW392

Walker Reservoir 3,600 acre-feet

100 cfs filling right from Brighton Ditch

Storage of augmentation replacement water

Case No. 03CW414

ARR B Underground Storage: 920 acre-feet

Surface Storage Right: 5,200 acre-feet

Case No. 03CW415

Terminal Storage at Aurora Reservoir, Quincy

Reservoir, and East Reservoir: 46,400 acre-feet

Dry Creek

South Platte River

Brighton

Fort Lupton

The Great MODFLOW Debate

What is the correct value for Riverbed Conductance? What is Riverbed Conductance?

– A parameter used in the MODFLOW River Package (RIV) to compute the rate of leakage from the river to the underlying alluvium

Riverbed Conductance = Kvsb/m

Where: Kvsb = Riverbed hydraulic conductivity in feet/day m = Thickness of riverbed material in feet

Very little, if any, hard data available for Kvsb or m Riverbed Conductance or Kvsb/m ratio normally estimated during MODFLOW calibration process Aurora’s MODFLOW modeling team (Tetra Tech, Deere & Ault Consultants, and Dr. Eileen Poeter) estimated values for Kvsb:

Initial Kvsb/m = 100 feet/day/foot

Final Calibrated Value of Kvsb/m = 55 feet/day

Centennial Water and Sanitation District’s consultant, Dr. Catherine Kraeger-Rovey of W&EST indicated that the South Platte River has a low permeability stream bed layer and recommended:

Kvsb/m = 1.337 feet/day/foot

For stipulation purposes, Aurora agreed to use:

Kvsb/m = 1.337 feet/day

0%

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Comparison of URF Curves for Well VW-14

Tetra Tech MODFLOW

AWAS

Tetra Tech MODFLOW w/ W&EST Riverbed Conductance

Distance to River: 410 ft

28 days to 90% Depletion

384 days to 90% Depletion

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Comparison of URF Curves for Well VW-15

Tetra Tech MODFLOW

AWAS

Tetra Tech MODFLOW w/ W&EST Riverbed Conductance

Distance to River: 570 ft

20 days to 90% Depletion

381 days to 90% Depletion

VW-15

VW-14

Future Slurry Wall and Impermeable

Barriers Impacting URFs

Summary of

Aurora’s Prairie Waters Project

Completion of Initial Project Feasibility Study: June 2004

Ground Breaking: July 2007

First delivery of water to Aurora: October 2010

34 miles of 60-inch diameter pipe

Supply Pipeline Capacity: 50 mgd (77.4 cfs)

17 Alluvial Wells (current): 12 mgd (490 gpm/well)

49 Alluvial Wells at buildout

Project Cost: $638,000,000

Current Project Firm Yield: 10,000 acre-feet per year

Ultimate Project Firm Yield: 50,000 acre-feet per year