My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
2010-11-23_REVISION - C1981019
DRMS
>
Day Forward
>
Revision
>
Coal
>
C1981019
>
2010-11-23_REVISION - C1981019
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
8/24/2016 4:27:15 PM
Creation date
11/24/2010 9:56:01 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1981019
IBM Index Class Name
REVISION
Doc Date
11/23/2010
Doc Name
Review Letter
From
DRMS
To
Colowyo Coal Company
Type & Sequence
SL4
Email Name
JRS
SB1
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.
/
9
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
decreases as surface cover and soil biomass increase, thus protecting the soil from rain <br />splash and runoff. <br />The P factor is an expression of the effects of supporting conservation practices, such as <br />contouring, buffer strips of close-growing vegetation, and terracing, on soil loss at a <br />particular site. The value of "P" decreases with the use of these practices because they <br />reduce runoff volume and velocity and encourage the deposition of sediment on the <br />hillslope surface. The effectiveness of certain erosion-control practices varies <br />substantially due to local conditions. For example, contouring is far more effective in <br />low-rainfall areas than in high-rainfall areas. <br />Section IIA of the written findings for Partial Phase II Bond Release SL-03 documents <br />the methodology used and approved by the Division for soil loss. Colowyo used four <br />study blocks to calculate gross sediment yields from premining and reclaimed lands. <br />Colowyo used documented K values for premining soils and blended K value for post- <br />mining soils due to mixing. LS factors represented the premining and post-mining <br />slopes. C factors were selected based on year 2000 sampling results for the reference <br />area for the premining condition, and year 2000 sampling for the reclaimed study blocks <br />for the post-mining condition. The Division considers this methodology and these <br />parameter input assumptions valid to estimate premining and post-mining sediment <br />production for comparison purposes <br />Review of Results, Partial Phase II Bond Release SL-04, Sediment Demonstration <br />Section 4.0 of the SL-04 application calculates and discusses the estimated premining and <br />post-mining sediment production for the Phase II Bond Release areas. As in past Phase II <br />sediment loss demonstrations, Colowyo used the RUSLE equation, this time on each <br />separate reclamation block independently. Table 4 of the SL-04 application provides the <br />RUSLE parameter input and the estimated values for the premining and post-mining <br />conditions. <br />The Division agrees with the fixed value for the R factor as 19 for both the premining and <br />post-mining condition on all reclamation parcels. <br />The Division agrees with the premining values of the K factor based on the weighted <br />average of soils within each parcel and the weighted average value of .24 for the post- <br />mining condition, derived from the weighted average of all parcels. <br />The Division agrees with the variation of the LS factor for the premining and post-mining <br />condition, with the following comments. While the Division understands that post- <br />mining topography may from the premining topography, overall the site after reclamation <br />will generally have an equal amount of steep slope areas in the post-mining condition as <br />were present in the premining condition. This premise would also be true for moderate <br />and gentle slopes as well. Parcel by parcel, there are some significant differences in the <br />LS factors. However, the total of the premining LS factors used is 166.45, compared to a
The URL can be used to link to this page
Your browser does not support the video tag.