My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
GENERAL32632
DRMS
>
Back File Migration
>
General Documents
>
GENERAL32632
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
8/24/2016 7:55:04 PM
Creation date
11/23/2007 7:22:20 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1981071
IBM Index Class Name
General Documents
Doc Date
3/27/1997
Doc Name
PROPOSED DECISION & FINDINGS OF COMPLIANCE FOR RN3
Permit Index Doc Type
FINDINGS
Media Type
D
Archive
No
There are no annotations on this page.
Document management portal powered by Laserfiche WebLink 9 © 1998-2015
Laserfiche.
All rights reserved.
/
132
PDF
Print
Pages to print
Enter page numbers and/or page ranges separated by commas. For example, 1,3,5-12.
After downloading, print the document using a PDF reader (e.g. Adobe Reader).
View images
View plain text
water quality changes is projected since only a very small portion of the streamflow <br />comes from adjacent bedrock groundwater dischazge. Surface water quality data <br />collected along Fish Creek, and presented by the applicant in Exhibit Tj, reveal no <br />significant changes in water quality as a result of undermining and subsidence. <br />Some increases in permeability of the aquifer units above the subsided azea was expected <br />up to 600 feet above the Foidel Creek workings. However, after completion of mining, <br />the permeability of the disturbed strata should return to close to pre-mining levels. <br />Review of the data and analysis of Exhibit Tj reveals that shallow bedrock wells <br />completed below the alluvium did show dewatering and casing damage due to <br />subsidence. However, this was likely due to the increased permeability created by tensile <br />stresses within 50 feet of the surface. Water levels showed rapid decline followed by <br />slow recovery and have now recovered to neazly pre-mining levels, as was anticipated. <br />The Fish Creek alluvial aquifer should not be affected due to its fine-grained nature and <br />the neazly 1000 feet of sepazation from the mine workings. Alluvial wells showed slight <br />impacts (see GWAP-7) but it is not clear whether these small water level changes aze <br />due to water loss to the bedrock below or to re-consolidation of the alluvial body. <br />Regazdless, no changes in Fish Creek alluvial water levels in lower Fish Creek have <br />occurred. <br />No impact to groundwater quality is predicted. Subsidence could cause inter- <br />communication of aquifers. The two aquifers of significance above the workings aze the <br />Fish Creek alluvial aquifer and the Twentymile Sandstone aquifer. No interaction <br />between these aquifers was predicted due to their physical separation. <br />As stated previously in the Trout Creek AVF Findings [he 1.5:1 relationship between soil <br />salinity and irrigation water salinity is considered to be a conservative assumption (the <br />actual relationship may be less than 1.5:1). Data collected by the Division on August l5, <br />1986, showed root zone soil conductivity to be slightly lower than Fish Creek surface <br />water conductivity. Additional detail on the projected impacts to the Fish Creek AVF <br />may be found in the Division's May 9, 1996 Findings for Foidel Creek Mine's Permit <br />Revision No. 3. <br />The major portion of the Fish Creek Alluvial Valley Floor is not flood irrigated but is <br />assumed to be sub-irrigated based on vegetation types, alluvial water depths and late <br />growing season color infrared photography. Material damage to sub-irrigated vegetation <br />would not occur because the majority of discharge to the aquifer occurs during spring <br />and eazly summer when mine discharge is diluted by high runoff volumes. <br />Permit Table 17 shows a predicted alluvial water quality on Fish Creek of approximately <br />1000 umhos/cm. Well 008-AU-3 on Fish Creek corresponds more closely with surface <br />water quality and is thought to be a more representative site than 006-AW-2. Based on <br />008-AU-3, a measurable increase in salinity of alluvial aquifers is projected, but the <br />predicted conductivity would be well below the 3000 umhos/cm material damage suspect <br />39 <br />
The URL can be used to link to this page
Your browser does not support the video tag.