My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
2020-11-30_REVISION - M1977300
DRMS
>
Day Forward
>
Revision
>
Minerals
>
M1977300
>
2020-11-30_REVISION - M1977300
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
1/9/2025 4:54:58 AM
Creation date
11/30/2020 11:49:35 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1977300
IBM Index Class Name
Revision
Doc Date
11/30/2020
Doc Name
Adequacy Review Response
From
Colorado Legacy Land
To
DRMS
Type & Sequence
AM5
Email Name
AME
MAC
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.
/
99
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
COLORADO LEGACY LAND <br /> SCHWARTZWALDER MINE <br /> The former Black Forest Mine is a dry underground aggregate mine wholly owned by Colorado Legacy Land, <br /> LLC (CLL) and within CLL's property boundary. It has an estimated capacity of 15,000 CY. The former Black <br /> Forest Mine permit(Permit No.M-2001-036)was formally closed in 2019. In accordance with Colorado Hard <br /> Rock Mining Rule 6.4.21.(19),CLL proposes disposing of excavated materials from the alluvial valley in either <br /> the former Black Forest Mine or the CV Glory Hole of the Schwartzwalder Mine. Technical Revision 14 <br /> documents the de minimums impact of alluvial soils disposed of in the CV Glory Hole. The former Black Forest <br /> Mine is a dry mine and is not connected to the adjacent Schwartzwalder mine workings. Dry mines do not have <br /> the opportunity to contact surface water or groundwater,therefore the impacts to water quality onsite are de <br /> minimis. Furthermore, as stated in Technical Revision 14, "...waste rock within the alluvial fill has <br /> demonstrated no propensity to acidify groundwater. This is based on sampling of several small seeps and the <br /> fact that pH of deep bedrock groundwater in the vicinity of the CV Glory Hole is approximately neutral or <br /> slightly basic." The floor of the main entrance and escape portal for the Black Forest Mine are included in the <br /> current Schwartzwalder Mine affected area boundary. These entrances are currently closed with gates. Once <br /> alluvial valley excavation and disposal in the Black Forest is complete, the main entrance and escape portal <br /> gates shall be backfilled either with rockfill or soil cement for aesthetic purposes: <br /> • Adit Backfilling-Rockfill: Prior to backfilling adits,all wood,garbage,cribbing,or other vegetative <br /> materials shall be removed. Adits shall be backfilled to a minimum depth of fifteen feet(15')from the <br /> inner top of the fill to the outer top of the fill. There shall be no spaces between the top of the fill and <br /> the roof of the adit that exceed three inches(3")and there shall be no space between the top of the fill <br /> and the roof of the adit at the entrance of the adit. The innermost three feet (3') of the backfill shall <br /> consist entirely of large diameter rock (<1') sourced from onsite. The remainder of the fill with the <br /> exception of the outermost one foot(1')shall consist of Rockfill mixed with Common Fill to minimize <br /> visible void space between the rocks. The outermost one foot(1') of backfill shall consist of suitable <br /> plant-growth medium. <br /> • Adit Backfilling-Soil Cement Backfill:Alternatively,if acceptable rock is not available,a soil cement <br /> mixture may be used. The soil cement will consist of on-site soil mixed with Portland cement in a ratio <br /> of 20:1 by volume(20 units of soil to 1 unit of cement). The on-site materials shall be well graded,with <br /> less than 5% passing the No. 200 Sieve, contain sufficient water to feel moist. The soil shall not be <br /> acidic or toxic in nature. Soil materials and Portland cement shall be thoroughly blended by <br /> mechanical means prior to placement. This may be done by machine or by hand. The entire length of <br /> the backfill except for the outermost three feet (3') feet shall be composed of soil cement. The <br /> outermost three feet(3')shall be composed of backfill material suitable for plant growth. <br /> These adit backfilling closure specifications (above) are summarized from the Colorado Inactive Mine <br /> Reclamation Program's General Bid Specifications (Division of Reclamation, Mining & Safety, March 2009). <br /> This voluntary backfilling shall be completed consistent with the surrounding topography(approximately 15- <br /> 30%slopes,as shown in Figure F-1)for a more"natural looking"closure. Backfilling shall be conducted along <br /> with the alluvial valley restoration and regrading once excavation is complete. It is anticipated that this work <br /> will be completed in the 2021 calendar year. <br /> This reclamation strategy is consistent with the current disposal strategy and regulatory principles for <br /> maximizing the long-term protection of human health and the environment. Disposal inside underground mine <br /> workings provides complete/permanent isolation from active surface environment,no impact or de minimis <br /> impact to onsite water quality,no long-term maintenance,and no additional engineering design. This strategy <br /> NOVEMBER 2020 11 AMENDMENT 5 <br />
The URL can be used to link to this page
Your browser does not support the video tag.