2003-02-05_REVISION - M1998013

• Permit No: M1998013
• IBM Index Class Name: Revision
• Doc Date: 2/5/2003
• Doc Name: Draft Technical Specifications for Slurry Wall
• From: DMG
• To: DMG
• Type & Sequence: AM1
• Media Type: D
• Archive: No

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STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
DIVISION OF
MINERALS
GEOLOGY
RECLAMATION
MINING•SAFETY
Bill Owens
DATE: February 5, 2003 eovemor.
/ Greg E. Walther
TO: Gregg Squire / Executive Director
~ /~ Ronald W. Cattany
i/ `% v~ Acting Division Director
FROM: Allen Sorenron
e~~ew
RE: ra echncca[ Specifications or Scurry N~'all, Reclamation Cost Fstimaie, and
tability Analysis, Hall-Irwin Corporation. T .e 'hores Resource GraveLPit_ ,~":
Amendment atpplieation r9M-OI, Permit No. M-1998-013 _ '
T'he Division of Minerals and Geology ;LMG) has reviewed the "Draft Tecdmicai Specifications fur
trtii t'~:mstracticn of the Shores Resource Slurry Wall,'- daten fanuary 2003: if the follow-ing minor - ~ ~ ~ _.
changes frrc- ircotporated into the !;ethnical specifications, DMG has detertitined that a sl.uxry wall -
constnrcted in accordance with these specifications should rnLet. leahai?e criteria establtsaed ~y the . ,
Office of the State Engineer for sealed water storage reserv;rirs
]. ltern 1.01 of section O10i0 of division 1 of the specifications should ber.l~anged :o include
units (linear feat) fvr the '°20,000 of slurry wall" to he installed. ~ ~ ~ " .
2. Item 1.02 ui section, 01300 of division 1- of the specifications should be changed tti inch3de~. ~~~
unit, {c:entimeters per second) For the maximum permeability of the soil-bentonite bdckfill.
3. [n Table i included with the specifications, change the specified value.. for sand content in
the slurry to state "sand content less than 20 percent by vofime.",
Since the DMG accepts the sufficiency of the specifications for installation of an adequate leakage
barrier, the Applicant. will be eligible for the 20 percent slurry wa11_ bonding option described. ir.
DMG written guidance and policy memoranda) once the slurry wall is installed and the
construction report and certification has been reviewed and accepted by DMG. Because ground
water is currently exposed by mining operations that have occurred within the proposed slurry wall
perimeter, the Applicant must post a bond including 100 percent of estimated costs to construct the
slurry wall in order to obtain approval of permit amendment AM-O1. The required. bond amount, as
calculated by the Applicant and summazized in the Reclamation Cost Estimate Table included in the
Tetra Tech RMC letter dated 2/4/03, must be modified as follows:
t September 2000, "Guide [o Specifications Preparation for Slurry Walls and Clay Liners as a Component of a Colorado
Mined Land Reclamation Permit," Colorado Department of Natural Resources. Division of Minerals and Geology.