REV92929

• Permit No: M1988048
• IBM Index Class Name: Revision
• Doc Date: 4/24/2000
• Doc Name: COMMENTS ON ANDESITE ROCK CO CARR GRAVEL RESOURCE AMENDMENT PN M-1988-048 AM -001
• From: DMG
• To: WEST GREELEY SOIL CONSERVATION DISTRICT
• Type & Sequence: AM1
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department o(Nalural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FA%: [phone]
DATE: April 6, 2000
TO: Gregg Squire
DIVISION OF
MINERALS
St
GEOLOGY
RECLAMATION
MIN ING•SAFETY
B~II Owens
Governor
Greg E. Watcher
FROM: Allen Sorenson ~ EzecuGve Director
Michael B. Long
RE: Review of Plan to Construct Water Storage Reservoirs, Andesite Rock Compa'riyDieCt°`
Carr Gravel Resource, Permit No. M-88-048
The following items must be addressed prior to approval of the plan to reclaim the area being amended
into the permit by construction of two water storage reservoirs. This review is limited [o the stability of
the reservoirs and the estimated installation costs.
In Exhibit D to [he permit amendment application, the Applicant estimates the 100,400 cu. yds. of
mixed overburden and shale will be required to install the proposed dike, pad, berms and clay-liner
for the reservoirs. The Applicant must provide details on the assumptions that form the basis and
the calculations used to derive this estimated volume. Rough calculation based on the information
contained in the amendment application indicate [ha[ [he dike, a[ 16 fee[ high with a 50 foot crest
width, 3:1 outslopes, and a 3 foot deep keyway would require 75,000 compacted cu. yds. of fill.
There is insufficient information on dimensions in [he application [o accurately estimate [he volume
of the proposed wedge shaped clay liner, but rough estimates indicate that at least 110,000
compacted cubic yards would be required for construction. The backfill required for the liner
keyway, the berms, and the pad would further add to the amount of mixed shale and overburden to
complete the project.
2. The unit costs applied in Exhibit L to the backfilling of the mixed shale and overburden for
construction of the reservoirs appear to be too low to assure and adequate reclamation bond will be
in place. The Division has completed an independent estimate of the costs to construct the reservoir
berms, liner, dike and install the inter-reservoir culvert. The Division's estimate inputs the material
volume contained in the application for the mixed shale and overburden fill. If the Applicant's
responses to item l above result in a modified volume, the cost estimate for backfilling must also be
modified accordingly. The cost estimate is broken down as follows:
Ripping of shale from the floor of the pit for blending with overburden and placement to construct
[he reservoir liner, berms and dike at $7,465.00 (see attached estimating worksheet). It is assumed
that the shale can be ripped and excavated from the locations requiring keyways; hence a separate
cost for cutting the keyways is not included in the Division's estimate. The volume of shale ripped
from the pit floor is one-half [he total volume of backfill required assuming a 50/50 mix with
stockpiled overburden.