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~ ~ III IIIIIIIIIIIII III Egviroq-qeqt, Iqc. LARRY E. O~BRIAN PIIEtIDENT August 19, 1981 9989 WEST 80TH AVENUE ARVADA~COLORADO 80004 303-423-7297 ~~~~~~~~ Mr . Jay Lucas /~~ G 2 0 1981 Reclamation Specialist Mined Land Reclamation 1313 Sherman, Room 423 fJIINED LAND R[CLANIATIDN Denver , CO 80203 Colo. Dept. of i~~alural Resoi~!ces Dear Mr. Lucas, Re The Robinson Brick and Tile Company Chieftain South Mine - MLR File No. 81-148 Thank you for your adequacy review The following is our response and mat as was used in your letter. Exhibit C - Affected Lands letter of August 10, 1981. uses the same numbering for- Thank you for your suggestion. Exhibit D - Mining Plan 1) Although it would be possible to salvage the B-horizon and stockpile it separately from the A-horizon, such a procedure would have questionable value. Partial reconstruction of the horizon structure is certainly possible on this and most other sites, but its cost-benefit ratio is very questionable. The establishment of vegetation is primarily dependent upon the A-horizon. Sustained growth requires, at best, a good subsoil drainage. On this site the B-horizon is a blocky, clay loam that would not provide good drainage. The process of redistribut- ing the B-horizon, if salvaged, would produce a compacted zone between the two horizons. This would further hinder drainage. On the steeper slopes it could produce a clay slip-zone between the two layers. Such a compacted boundary could also encourage the formation of a clay pan. The B-horizon is considered part of the overburden. By mix- ing the more sandy materials below the B-horizon with the clay materials, a better subsoil drainage is obtained than is now present. If the B-horizon was a lighter medium and there was no sandy material below it, the separation of the A- and B-horizons could