REV89818 - Laserfiche WebLink

Home Browse Search

sss STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY DPNa rlmenl of Natural Resource 131 3 Sherman SL, Room 21 5 Denier. Colorado 80203 Phone: (303) rib6-3567 FAX: (3031 832-A 106 DATE: January 30, 1997 TO: Harry Ranney //,n, -- FROM: Dan Mathews r ~ u"1 F tB 0 71997 RE: Chimney Rock Mine (C-S1-023) Revegetation Evaluation for Phase 2 Bond Release ~'~ ~~~~~ DEPARTMENT OF NATURAL RESOURCES Roy Romrr Governor ~a mes 5. I ochheaA Esecuuve Dire<lor Michael A. Long Division Direao~ I have reviewed the January 9, 1997, responses submitted by Greystone, in response to our adequacy letter regarding the referenced subject. My comments are listed below. 1. Information provided in response to this item is in general sufficient, assuming that timing and details of reclamation and maintenance activities are described in the annual reclamation reports as indicated. This information should be incorporated into the amended bond release application. A control program targeting thistle and knapweed is mentioned, but there is no reference to control of field bindweed, and this should be addressed. 2. In the initial review letter, we had indicated that cover sampling methods and the sample size adequacy formulas used were appropriate (in fact the adequacy formula employed was more stringent than required). One item which was overlooked in our earlier review, is that although sample adequacy was achieved in each sampled parcel, sample sizes were smaller than recommended in the Division's bond release guideline. Within parcel sample size ranged from three to ten transects, whereas the guideline recommends a minimum of 15 to 20 sample observations. The small sample sizes employed are probably related to the relatively small areas involved, but some justification should be presented for the sample sizes selected, and the departure from the recommendation in the guideline. Also, the acreage of each sampled parcel should be specified in the table on page A-2, or elsewhere in the application. 3. Cover data was adjusted as requested to eliminate annuals, biennials, and noxious weeds from the data used for reference area comparison. The applicable cover standard was still achieved for all sampled parcels, following this adjustment. It should be noted nevertheless, that field bindweed, a noxious weed, is a significant component of the East Slope, south slope, and 1991 AVF areas