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iiiiiiiiniuiiiiii 999 December 10. 1:'GO Mr. Piark S. Loge Reclamation Specialist ;dined Lana Reclamation IIoard 1313 Sherman, Room 423 Denver, Colorado 80203 _ , -. ~" ~ ;, ;n"~ RE: ,3rannan Sand & Gravel Cor.!pany DLC.A. 29 Sob No. 354.1 Dear t~,r. Loge: This letter is written i^ response to the memo from your office dated October 30, 1980 to Ann I:odgson of Brannan Sand and Gravel referencing some concerns about tdCA 29. On Page 3 of your letter, Item ~1 under the reference to Exhibit D, we understand the concern is with the sealing o£ the northwestern perimeter of Parcel e of that proposed pit. finder Item #1 the statement is made that thH "sealing is necessary to maintain a ten-foot dif- ference in final water levels in the two pits". Uur report sta- te~ and we further errptrasize that the estimated ten-foot water level differential is a re:rult of the sealing effect of fines deposited along the north and west perimeter of Parcel B. 'Phew depo»its will occur over a pericd of time and the estimated ten- foot differential in water levels between the two Bits will t,e the progressive result especially ;luring the R;ining and to a lesser degree after miring when conditions 1,ave staCilized within. the two proposed pits. Item ~1 cf that ex!!ibit goes cn to ask "why will this area cf shoreline "seal" itself while others will no t7" Our report did not suggest that otsrer areas will not be sealee to some degree, however, the notthwe»tern perimeter of Yarcel l3 will tend to be sealed quicker and to a greater degree due to the ground water flow patterns franc Parcel B toward Yatcel A as shown in the attached drawing. As tt,e figure indicates, the existing ground water flow is generally From the southeast toward the northwest across the entire site and will continue in that general direction once the two pits are constructed. In sdc'.iticn, due to the very narrow stretch of unmined property near the northwestern perin',eter of. Parcel ti, the ground water flow and sealing will be directly proportional to the density of the flow lines between the two parcels as st,own on the attached iiyuce. During mining and construction cf the pir_s a great deal c;f sr:;i- ment will be stirred up and due to the direction c,f flra~ out of the pit, the fines will be concentrated against the west anci nortP: perimeter of Parcel B as shown on th<_~ attact:eu r,ruwing.