2003-09-10_HYDROLOGY - M2001085 - Laserfiche WebLink

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Mr. Les Ewegan page 2 including Water Supply paper 1658, 1964, and Hydrologic Investigations Atlas HA-736, 2003, in developing the aquifer parameters. What was determined to be surrounding aquifer were specific yield values of e19 t to 20 appropriate for the pit area and of 550 to 4,444 gpd/? and a saturated thickness of IS to 20 feet The purmpinn ty moues the pit simulated as a very large diameter well for g rate pplied to diameter), was 1,200 purposes of this analysis (950 to 1,000-feet BM as per our earlier phone discussions. The Company well No. 420-R is located a significant distance from the it loc l being approximately 3,000 feet from the closest point of contact with a e, that the active mining area. Given the above information it is intuitively obvious that the operations at the it ar highly unlikely to be the source of any drawdown that ou p are Company well. To dewater an area may-Or may not be occurring at the around the pit to a distance of 3,000 feet would involve the absolute removal from the hydrologic system of at leW seal thousand acre-feet of This would take several years at a continuous rate of 1,200 water. o1uta a- b_ _sence gPm, and this would have to be in the of water. Of any recharge to the system whatsoever or buffering effects ftom open bodies Nonetheless. we have carried out an idealized distance-drawdown analysis to determine the limit of drawdown from the pit under conditions eliminating the river rech effects of the numerous indicated above and resin and the gradient driven undertlow, .The parameters applied are as . predictions of no discernable drawdown of from 163-feet to 915- feet. Thus it appears that there is no way the pit dewatering operations could have caused foot drop in the water table at 3,000-feet distance even in the absence ofany ofthe bufferin afour- recharging factors that do exist in reality and that do impact the propagation of drawdown 8 and from the pit dewatering operations. ffects We note that the recent four years have seen the climax of the worn history for the subject area, It is not at all unlikely that some changes in water tabl resulting from the extremely low river flows and associated law t drought in recorded last few years. Mr. Grandlienard, in his initial letter to you of Jul 28 2003, e would be reported drop in the water level in well 420-R was first n ?? alluvial water table over the is at the height of the drought and, if the level changes-are valid y 003, states that the This this extremely unusual and severe weather event. We noted in note that April Mr. and May of last Grandiienard year, has not presented any records of the water table over the 1959 (dae of are as likely as not reflections of period except to note that the change was observed last year. He infers that of well) to been no ?a?ge whatsoever until lest year. It ?? at least t there has thus been could have been gradually occurring and that the age flth bwell, thatthe 44 rtar level changes additional factor Mr. Grandlienard makes references to anecdotal reports of to Bred water be an levels in other pits and lakes in the area, but there is no substantiated evidence of this presented in his complaint letter. d water • JW'7r'l" a17d Iftod I MM, Gbmir/fanrs Inc. z-d ESTEL62E0E ONI U03UU dES:20 60 OT des