My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
GENERAL50712
DRMS
>
Back File Migration
>
General Documents
>
GENERAL50712
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
8/24/2016 8:37:17 PM
Creation date
11/23/2007 6:11:40 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1981034
IBM Index Class Name
General Documents
Doc Date
7/29/1988
Doc Name
PROPOSED DECISION & FINDINGS OF COMPLIANCE FOR RN1
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.
/
26
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
<br />Once the coal seam aquifers are reestablished, (when the workings have filled <br />with water after cessation of mining) discharge will probably again be to the <br />glacial/alluvial aquifer through the coal seam subcrop. The applicant has <br />calculated that the flow through the glacial/alluvial aquifer is about 1.53 <br />cfs. Assuming that the discharge from the coal aquifers will be equal to the <br />mine inflows, about 0.11 cfs will be discharging from the two coal seams into <br />the glacial/alluvial aquifer. According to this scenario, the discharge from <br />the two coal seams represents about 7% of the total flow in the <br />glacial/alluvial aquifer. <br />A mass balance analysis conducted by the Division predicted that the resultant <br />post-mining TDS concentrations in the glacial/alluvial aquifer would be about <br />900 mg/1. The pre-mining TDS concentration in the aquifer averaged about 330 <br />mg/1. This increase of 570 mg/1 is probably a worst case. The assumptions <br />and variables used in the analysis are the same as those used by the applicant <br />to predict post-mining water quality in Ward Creek (see page 68 of Volume 8 of <br />the application, September 9, 1982, addendum). <br />This change in water quality could affect water use patterns in the vicinity <br />of the mines. A TDS of 900 mg/1 is high for domestic uses. Information in <br />the application indicates that there is little domestic use of ground water in <br />the area. Most domestic water users obtain their water supply from the Colby <br />municipal water line. Other users of water (stock, irrigation, and <br />industrial) should not be significantly affected by the predicted water <br />quality change. Monitoring of water will be conducted to verify these <br />predictions. <br />The applicant placed mine development waste in old abandoned strip mine pits <br />(see Map 2.05.3(2)(b)-1 of the permit application). Some additional <br />disturbance was proposed but never occurred. The underground development <br />waste pile is completely underlain by bedrock and will not be in direct <br />contact with the unconsolidated glacial/alluvial material. The applicant has <br />determined that significant vertical permeabilities do not exist in the strata <br />near the mine (see pages 20-35 of Volume 8). Therefore, vertical infiltration <br />of leachate from the refuse pile into underlying aquifers should not be a <br />significant problem. <br />No predictions of specific quality are available, however, experience at <br />backfilled areas in northwestern Colorado suggest that a rough estimate of <br />volume can be calculated from an acreage analysis. Given 21 acres of <br />disturbance at Red Canyon, peak spoils discharge could reach 30 gallons per <br />minute following snowmelt. This value probably overestimates the discharge, <br />given the lower precipitation regime near Cedaredge. <br />-10- <br />
The URL can be used to link to this page
Your browser does not support the video tag.