WSP01846

• 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 3A - Hydrosphere's Model Requirements
• Water Supply Pro - Doc Type: Publication

S Metro GW Model Requirements Memo
5433

January 8, 2001
Page 2

2) Estimation of well and well-field production capacity under various water level
conditions.

3) Bedrock aquifer system response to various pumping (and injection) schedules that
may be considered as part of prescribed conjunctive management strategies,

4) Time frame for which the aquifers transition from confined to unconfined conditions,
and

5) Economic life, as characterized by transient production cost characteristics, of Denver
Basin aquifers under possible management alternatives.

It is important to note that rather than providing accurate predictions of bedrock aquifer response
to stresses, the subject model will be used to illustrate and compare the relative differences in
bedrock aquifer performance for the modeled scenarios. Given the acknowledged expectation of
some prediction inaccuracy, Hydrosphere will also attempt to characterize model predictive
uncertainty.

A secondary objective is to support cost analyses of both well-field development as well as
possible system operation scenarios. However, cost analyses will not be included in the current
model development effort.

2. SYSTEM TO BE MODELED

To address the listed model objectives, Hydrosphere will develop a predictive model of the
Denver basin bedrock aquifers.

Given project cost and schedule constraints, Hydrosphere will utilize the existing SEO Denver
Basin groundwater model ("SB-74 model") as the basis for the South Metro regional model.
Based on an investigation of available models and feedback provided at the 11/17/2000 Peer
Review meeting, no preferred alternatives to the SEO SB-74 model were identified. The model
domain will encompass the entire Denver Basin as described by Robson (1987), although the
shallow alluvial aquifers will not be explicitly considered.

The South Metro water supply system to be considered in the model must include: I) the four
Denver Basin bedrock aquifers (including prescribed boundary conditions), 2) water demands,
and 3) system operating procedures.

The conceptual model and numerical treatment of the Denver Basin aquifers as required to
adequately address project objectives are described in section 2.1 below. The water demand and
system operating procedures component of the South Metro bedrock groundwater water supply
system will be considered in the model through prescription of transient boundary conditions as
discussed in section 2.2.

Hydrosphere Resource Consultants
1002 Walnut Suite 200, Boulder, CO 80302
PO Box 44S, Socorro, NM 87801

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