My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
PERMFILE121731
DRMS
>
Back File Migration
>
Permit File
>
300000
>
PERMFILE121731
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
8/24/2016 10:20:00 PM
Creation date
11/25/2007 9:39:35 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M2000156
IBM Index Class Name
Permit File
Doc Date
3/15/2001
Doc Name
ADEQUACY REVIEW COULSON EXCAVATING CO INC BONSER PIT FN M-2000-156
From
DMG
To
COULSON EXCAVATING CO INC
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.
/
10
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
Memo to Gregg Squire 3 March 13 2001 <br />reclaimed pit floor or otherwise destabilize the liner. The Division suggests that the Applicant <br />modify the reclamation plan to include keying the liner into the bedrock or provide a <br />demonstration that the clay liner will not fail under the plan currently proposed. <br />b) The application states that the depth to ground water in the area of the proposed pit is 12 to 1 S feet <br />below ground surface. At these depths, ground water pressure is unlikely to destabilize the <br />reclaimed pit slopes. However, the Division observed during the pre-operational inspection of the <br />proposed Bonser Pit that the existing pond in the southwest comer of the site has a water surface <br />only a few feet below the surrounding ground. The Division requests that the Applicant describe <br />the basis for the determination that the water table is 12 to 1 S feet deep and provide any <br />documentation (borehole logs, piezometer data, etc.) demonstrating the depth to ground water. A <br />high water table at any location around the perimeter of the reclaimed pit could cause increased <br />seepage into the pit, and potentially bulging or failure of the reclaimed pit slope. Mitigation for <br />the effect of a high water table could be to buttress the slopes, install drainage facilities, or <br />construct the slopes at a shallower angle. <br />c) Even though the installation of a liner will limit ground water inflows to the reclaimed pit, the <br />amount of water that will seep through the liner may be sufficient to create swampy ground. <br />Swampy ground would not be suitable for the proposed post mining land use of cropland and may <br />leach salts from the underlying compacted clay creating an alkali condition also unsuitable for <br />cropland. Moreover, if floodwaters from the Big Thompson River were to spill into the pit with no <br />facilities for pumping or otherwise removing the water back to the river, asemi-permanent lake <br />would be created further compromising the lands use for crops. The Applicant must describe how <br />seepage into the pit will be managed to prevent interference with the cropland use, and must <br />describe how floodwater will be returned to the river or otherwise managed following a large <br />flood. Similar to the aforementioned R&O Pit, a pond could be constructed in the pit floor and act <br />as a sump to collect any ongoing seepage. For elimination of floodwaters, pumping would likely <br />be required since drainage to the river by gravity does not appear to be feasible. <br />d) The following list of items must be incorporated by the Applicant into the liner specifications: <br />i) The liner soil will contain a minimum of 50 percent material passing the No. 200 sieve on a <br />dry weight basis. <br />ii) The liner soil will have a plasticity index of from ] 0 to 35 percent. <br />iii) The percentage of gravel, defined as material retained on the No. 4 sieve, will not exceed <br />10 percent. <br />iv) The liner soil will be compacted to a minimum of 95 percent maximum dry density as <br />determined by the Standard Proctor (ASTM D698). <br />v) No brush, roots, sod, frozen material, or other deleterious or unsuitable materials shall be <br />incorporated into the fill. Fill shall not be placed upon frozen material. <br />vi) If moisture conditioning is required to meet the moisture content specification, the added <br />moisture shall be worked into the fill by harrowing or other means until a uniform <br />distribution of moisture is obtained. <br />vii) Compacted soil liner fill shall be protected from desiccation and from freezing. The <br />finished soil liner will be covered as soon as practicable with the layer of overburden and <br />
The URL can be used to link to this page
Your browser does not support the video tag.