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The recharge rate for the CYCC Eckman Park mine area backfill • <br />study was taken as 3 inches per year because the calculations <br />related to an old reclaimed area which appears to be stabilized. <br />The fact that the reclaimed areas under considerations are on a <br />north-facing slope as opposed to a west-facing slope, as in the <br />Seneca mine study, may result in increased snow pack, snow melt <br />period and recharge. However, the recharge rate of 3 inches is <br />still considered to be a reasonable figure. This value is <br />relatively high considering that the snowfall in this area <br />accounts for about 508 of the average annual 16 inches of <br />precipitation. Consequently, the 3 inches of recharge, which <br />appears to occur primarily from snowmelt, constitutes about 308 <br />of the total available water during the recharge period. <br />Most o£ the recharge to the backfill area is assumed to occur <br />during the snowmelt period from mid-April to mid-June. The area <br />of recharge for the eastern backfill area is approximately 6x10 <br />square feet. The total volume of recharge is therefore about 1.5 <br />x lOT ft1/yr., equivalent to an average rate of about 200gpm. <br />(Appendix II, A). <br />Discharge <br />Limited discharge rate data for the Area 2 Pit are available from • <br />mid-June to mid-July, 1965. Discharge data from the Pond F <br />Spring are available from mid-June to April 1986. The discharge <br />data are shown on Figure 5. Both discharge areas show a signifi- <br />cant increase in rate during the snowmelt period. During this <br />time water levels in the central part of the backfill area are at <br />maximum levels. This results in maximum hydraulic gradients <br />towards the discharge areas and maximum saturated backfill <br />thickness. As the snowmelt recharge period ends, groundwater <br />discharge is derived from storage in the backfill resulting in a <br />decline in water levels, a decrease in the hydraulic gradient and <br />saturated backfill thickness and a resulting decreases in <br />discharge rate. <br />Data for the peak discharge period during 1986 is available from <br />the Pond F Spring. The peak discharge for the Pond F Spring was <br />about 1300 gpm. The 1985 data indicates that discharge to the <br />Area 2 Pit is approximately equal to that from the Pond F Spring. <br />It is therefore projected that maximum total discharge from the <br />eastern backfill area is in the order of 2000gpm. The total <br />discharge rate drops to less than 80gpm during the later part of <br />the year, so that the average discharge rate over the year would <br />be in the order of 200gpm. This is very similar to the total of <br />recharge that occurs on an annual basis. This indicates that the <br />flow system in the eastern backfill area approaches a "closed <br />system" with recharge to the system accounting for almost all of <br />the discharge from the system when considered over a long period • <br />of time such as a complete year so that overall storage changes <br />are minimal. When considered in this context volume difference <br />7 <br />