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Location
<br />X (ft)
<br />W (ft)
<br />T (gpd /ft)
<br />S.Y.
<br />Cell 1
<br />2,083
<br />9,403
<br />14,483
<br />0.2
<br />Cell 2
<br />843
<br />9,246
<br />10,338
<br />0.2
<br />Cell 3
<br />2,320
<br />10,427
<br />14,483
<br />0.2
<br />Cell 4
<br />889
<br />7,590
<br />10,338
<br />0.2
<br />Cell 5
<br />2,725
<br />8,954
<br />15,414
<br />0.2
<br />Cell 6
<br />2,032
<br />8,924
<br />13,775
<br />0.2
<br />Cell 7
<br />1,032
<br />8,902
<br />12,264
<br />0.2
<br />Cell 8
<br />306
<br />8,812
<br />9,364
<br />0.2
<br />Cell 9
<br />495
<br />8,772
<br />8,444
<br />0.2
<br />Cell 10
<br />1,015
<br />8,979
<br />9,540
<br />0.2
<br />Cell 11
<br />390
<br />8,181
<br />8,042
<br />0.2
<br />Cell 12
<br />782
<br />9,159
<br />9,527
<br />0.2
<br />SW Services Pump
<br />2,083
<br />9,403
<br />14,483
<br />0.2
<br />Ms. Michelle L. Hatcher
<br />Hokestra SWSP
<br />April 10, 2013
<br />Page 4 of 9
<br />The depletions from evaporation losses were lagged to the Saint Vrain River using a Glover
<br />analysis. The following aquifer parameters were used in the model:
<br />X - Distance from well to river, measured from the centroid of the exposed area
<br />W - Distance from the aquifer boundary through the well to the river channel
<br />T - Transmissivity of the alluvial aquifer between the well and the river (source: Tgrid0309 GIS layer from SPDSS)
<br />S.Y - Specific Yield
<br />The total lagged stream depletions from the operation of the Hokestra Pit during this plan
<br />period, not including dewatering operations, are 126.6 acre -feet. Taking into account dewatering
<br />accretions and lagged depletions as further discussed below, the total lagged stream depletions to
<br />be replaced during this approval period are 112.5 acre -feet. The monthly distribution of these
<br />depletions are summarized on the attached Table 17.
<br />Dewaterinq
<br />Dewatering has been occurring in Cell 2 and this cell will remain dewatered until
<br />completion of its liner scheduled for completion in August 2013. It has been assumed that this
<br />dewatering activity has reached a steady state condition where lagged depletions from
<br />dewatering activities are replaced by net accretions from the same lagged depletions.
<br />Dewatering will commence within Cells 3, 4, 5, & 6 in April 2013. With the start of dewatering
<br />activities in these cells the river will experience a net accretion as the volume of dewatering
<br />discharged to the river exceeds the lagged depletions generated by that dewatering. It is
<br />projected that dewatering at Cells 2 & 4 will cease in August 2013, and dewatering in Cells 3, 5,
<br />& 6 will cease in September 2013. After dewatering activities cease, the river will experience a
<br />net depletion as lagged depletions will continue to hit the river while the accretions will cease
<br />once dewatering water is no longer directed to the river. Due to expected completion of slurry
<br />wall liners the lagged depletions will not include depletions associated with a "first fill."
<br />Cells 5 & 6 are currently a ground water lake full of water. The initial dewatering rate,
<br />required to empty the filled cells, will be approximately 1,500 gpm. This water will be
<br />discharged directly to the river with no beneficial use. After the initial high dewatering rate, the
<br />County projects to have a lower pumping rate to maintain a dewatered state. The County
<br />projects the maintenance pumping rate to be equivalent to 50 gpm. Dewatering of the lake will
<br />not result in depletions to the stream system so long as the pit remains dewatered thus
<br />
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