HYDRO28780

• Permit No: M1979195
• IBM Index Class Name: Hydrology
• Doc Date: 2/24/2004
• Doc Name: Design Technical Memorandum
• From: GEI Consultants, Inc.
• To: Denver Water
• Media Type: D
• Archive: No

Hazeltine/Road Runners Resf II/Brinkmann-Woodward Gravel Pi[s Lining Project-Design Technical Memorandum
Denver Water
August 2003
TABLE 4.2
SUMMARY OF SELECTED ROCK
MASS HYDRAULIC CONDUCTIVITIES
De th Below To of Betlrock Feet
Section 0-2 2-4 4-6 6-8 8-10 10-12 12.14 14-16 16-18 18-20 20-22 22-24 24-50
1 S.Ox10~8 5.0x10"B 2.0x10"e
2 5.0x105 4.4x108 1.0x10' 2.Ox10~8
3 5.0x16' 2.Ox10~e
4 5.0%108 2.0%108
5 4.4x10.8 4.1 z10~8 2.Ox10~e
6 5.0x10° 4.1%108 5.0x10° 2.0x108
Notes:
1. All conductivities are in cm/sec
2. Cutoff wall conductivity = 1.OOx10~'
3. Alluvium conductivity = 3.OOx10~'
The upper portion of bedrock identified in the borings consists of intensely weathered and
intensely fractured claystone. Although this zone of intensely weathered and intensely
fractured bedrock ranged from 2 to 24 feet, it was generally identified to be between 2 to 4 feet
thick. Packer permeability tests could not be conducted in this intensely weathered and
intensely fractured zone. Therefore, we considered this zone to have a hydraulic conductivity
greater than the hydraulic conductivity of the intensely to moderately weathered and fractured
bedrock that could be tested. We assigned a hydraulic conductivity of 5 x 10-5 cm/sec to this
upper intensely weathered and intensely fractured zone of bedrock.
We used a hydraulic conductivity of 1.0 x ] 0~~ cm/sec to model the soil-bentonite cutoff wall
and a hydraulic conductivity of 3.0 x 10"2 cm/sec to model the alluvium above the bedrock.
4.5 Parametric Study
GEI performed a parametric study using the seepage analyses for each representative cross
section to evaluate the change in estimated seepage into the reservoir for various depths of
penetration of asoil-bentonite cutoff wall into the underlying bedrock. The seepage analyses
were performed for each representative section by varying the depth that the modeled soil-
bentonite cutoff wall extended into the bedrock layers for the hydraulic conductivity values
presented in Table 4.2. The depth the cutoff wall extended into bedrock was increased by 2-
foot intervals based on the stratigraphy of the section for each subsequent seepage analysis.
The results of the parametric study are summarized in Table 43.
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