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2008-08-25_REVISION - M1980244 (3)
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2008-08-25_REVISION - M1980244 (3)
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Last modified
6/15/2021 5:52:17 PM
Creation date
8/27/2008 3:16:12 PM
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Template:
DRMS Permit Index
Permit No
M1980244
IBM Index Class Name
REVISION
Doc Date
8/25/2008
Doc Name
PAR-Fax
From
DRMS
To
CC&V
Type & Sequence
AM9
Email Name
BMK
Media Type
D
Archive
No
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make it possible to include the dynamic relationships amongst the various <br />components of a system. AMEC used the Goldsim model to develop a dynamic <br />water balance for the Cresson project. <br />A probabilistic model was used for the monthly precipitation and evaporation and <br />dynamic relationships based on field water balance and flow observations are <br />included. The outcome is a much more realistic water balance model for <br />modeling the high heap and the complex interactions between the various <br />PSSA's and the plant. The fluid management system at the Cresson VLF has <br />been improved considerably over the last number of years and this provides <br />higher operational flexibility. <br />My review of the dynamic water balance model indicates that it is more realistic <br />than the static model for the large VLF at Cresson. It is an important <br />improvement in increasing the confidence in the overall fluid management of the <br />Cresson VLF. <br />4. Overall Design of Infiltration Layer - East Cresson <br />The present foundation conditions for the East Cresson Overburden Storage <br />facility consists of clayey materials. The site remains wet for a significant part of <br />the year as a result of the northerly aspect of the site and the presence, of clayey <br />foundation materials. Once the overburden storage facility is constructed it will <br />be regraded and covered and it is expected that the surface may behave similar <br />to present site conditions. Present infiltration rates into the subsoil and finally <br />into the Cripple Creek Diatreme, are controlled by the present site conditions, i.e. <br />the clayey nature of the foundation soils and the northerly aspect of the site. <br />The design of the overburden handling and storage facility in East Cresson relies <br />on the site characteristics to develop an environmentally protective facility. It is <br />proposed that some of the clayey foundation materials be removed and placed <br />on top of the facility as a cover to reduce infiltration from that of a bare <br />overburden storage facility. In effect the present surface soils conditions will be <br />re-established on top of the East Cresson storage facility. This is a very sound <br />concept. This cover is meant to reduce (not eliminate) infiltration of water and <br />also restrict air movement. <br />The present design (Figure 5 of the Adrian Brown report) calls for a 2 ft layer of <br />proof rolled clayey sand/gravel to be placed on top of the regraded overburden <br />material, followed by a 1 ft layer of compacted sand and gravel and then 6 <br />inches of growth medium. I have a concern about the thin cover on top of the <br />compacted clayey sand and gravel as the compacted clayey layer can be <br />subjected to erosion and cracking due to settlement of the underlying <br />overburden materials. Freeze-thaw cycles may further degrade this material. It is <br />6
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