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{ ? 11{ Illlfltllll{I rll <br />999 <br />SHB AGRA, INC. <br />1 6 1 Engineering & Environmental Services <br />-'t- <br />April 8, 1994 <br />hrt- ? 3- c <br />0 <br />165 South Union Blvd. <br />Suite 516 <br />Lakewood, Colorado <br />U.S.A. 80228 <br />Phone: 303-763-8432 <br />Fax: 303-989-5525 <br />Mr. William C. York-Feirn SHB AGRA Project E92-7075 <br />State of Colorado <br />Division of Minerals and Geology <br />1313 Sherman St., Room 215 <br />Denver, CO 80203 <br />RI`Cfil yrr' , <br />RE: Acid Potential of 4th Ridge Shale, Dowe Flats Project, APR 13 - <br />File No. M93-041, Southdown, Inc. 1994 <br />Dear Mr. York-Feirn: r1 r,4Jrter <br />?_ <br />As a condition of permit approval by the Colorado Mined Land Reclamation Board (CMLRB); <br />tests were performed to determine the acid potential of 4th Ridge Shale at the proposed Dowe <br />Flats Mine. A representative unweathered core sample of the limey-shale from boring DDH-3 <br />on the 4th Ridge was submitted to Hazen Research for analysis. Analytical tests included: acid <br />base potential, percent pyritic sulfur, percent sulfide sulfur, and pH from-a saturated paste. <br />Net acid potental for the sample submitted was 600, where a positive number indicates the <br />material is basic. The larger the positve number, the lower the acid potential. Based on this <br />result the acid potental is low. <br />The percent pyritic sulfur is 3.09% and the percent sulfide sulfur is 3.18%. The acid potential <br />from the sulfur content is determined by comapring the neutalization potential to the sulfur's <br />CaC03 equivalent. The closer this mumber is to one (1), the higher the acid potential. The <br />ratio for this sample is approximately 6.70, therefore the acid potential is considered low. <br />The pH obtained from a staurated paste was determined to be basic (8.04). A table of the <br />results is listed below and a copy of Hazen's results is attached. <br />TEST DESCRIPTION RESULT <br />Neutralization Potential, tons C8C03 equiv/1000 tons soil 666 <br />Net Acid/Base Potential, tons C8C03 equiv/1000 tons soil 600 <br />Pyritic Sulfur as S, °/6 3.09 <br />Sulfide Sulfur as S, % <br />. % S Converted to tons CBC03 equiv/1000 tons soil 3.18 <br />99.38 <br />pH of a Saturated Paste 8.04 <br />J AGRA <br />Fi r K f l& Em , rn a„m rt, t M l (J m u n