WSP01072

• File Number: 8449.926
• Description: South Metro Water Supply Study
• State: CO
• Basin: South Platte
• Date: 2/1/2004
• Author: SMWSS Board
• Title: Technical Appendices - Appendix 3C - Peer Review Model
• Water Supply Pro - Doc Type: Publication

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Memo

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To: Pat Mulhern, Mulhern MRE, Inc,
From: Ned Banta, Scott Mefford, George Chadwick
Date: 2/10/2004

Re: Peer Review of the Regional and Local Ground Water Models for the South Metro
Water Supply Study

Introduction

The purpose of this memorandum is to summarize the conclusions of our peer review group
regarding the groundwater models that were developed and used for evaluating various
water supply alternatives being considered in the South Metro Water Supply Study, The
models we reviewed include the regional groundwater model that was developed by
Hydrosphere Inc" and a local well model that was developed by HRS Water Consultants, Inc,
These two models are described in Chapters 3 and 4, respectively, of the study report', In
addition to the study report, the authors had access to selected data and maps provided by
Hydrosphere and HRS during the model review, The regional groundwater model is built
upon the foundations of the SB-74 model developed some years earlier by the State
Engineers Office, and others. The South Metro regional model was used to make
predictions of Mure regional water levels in the Denver Basin aquifers at 10-year increments
from 2010 through 2050. These predictions were used as input to the local well model, which
was used to predict the average pumping capacity of wells in the various Denver Basin
aquifers in and near the South Metro water provider areas, This information was then used
to estimate the number of water supply wells that would be needed by the South Metro water
suppliers through the year 2050 for the various water-supply alternatives.

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As is common in groundwater modeling efforts, the groundwater models that were developed
for this study were developed for a particular purpose. In this case the purpose of the
modeling effort is to provide some of the information that is needed to enable planners to
make a good decision regarding five general long-term water supply development
alternatives. For this study, those aKematives included:

Alternative 1A - Status Quo Alternative (Future Supplies through Non-Tributary
Groundwater)
Alternative 1 B - Status Quo Alternative with Storage for Peaking (Future Supplies through
Non-Tributary Groundwater with Storage for Peaking)
Alternative 2 - Non-Tributary Groundwater AKemative with Maximum Reuse
Alternative 3A - Conjunctive Use with Borrowing (Import of South Platte and Blue River
water during wet years with borrowing from Denver Water Storage)
Alternative 3B - Conjunctive Use of Free River Water (Import of South Platte and Blue River
water during wet years with direct diversions of junior water rights when available)

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