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REV04063
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REV04063
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Entry Properties
Last modified
8/25/2016 1:02:05 AM
Creation date
11/21/2007 9:14:40 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1980149
IBM Index Class Name
Revision
Doc Date
11/14/1994
From
WELD CO COLO
To
DNR
Type & Sequence
AM2
Media Type
D
Archive
No
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EXHIBIT G <br />6.0 WATER INFORMATION <br />The north property line is bounded by the St. Vrain Creek. The <br />property is bisected by the Last Chance Ditch. The mining <br />operation will maintain a minimum 150 feet setback from the St. <br />Vrain Creek thalweg and a 50 feet setback from the Last Chance <br />Ditch so that site activities will not structurally impact the side <br />slopes or significantly increase seepage from either conveyance <br />feature. Other water features on the site include three ponds as <br />shown on the Pre-Mining Plan. <br />Most of the site lies within the 100 year floodplain. The southern <br />portion of the site which is not in the floodplain will be used for <br />stockpiling topsoil. Fuel stored on site and production facilities <br />will also be kept in the area outside of the 100 year floodplain. <br />The mining plan entails dewatering of the site during the mining <br />phase. After mining is completed four (4) lakes will remain on the <br />site due to the high water table in the vicinity. <br />Presently on-site surface drainage naturally flows into the St. <br />Vrain Creek. The grading shown in the Mining Plan and Reclamation <br />Plan is designed to impound all on-site stormwater. <br />6.1 Dewatering Plan <br />The mine site is in an area with a high water table and water will <br />be exposed at the site due to sand and gravel mining. However the <br />mining area will be dewatered with a dewatering trench around the <br />perimeter of the pits. <br />As mining progresses the groundwater table will be lowered in each <br />mining phase by pumping to allow the aggregate to be mined under <br />dry conditions. Only one mining phase will be dewatered at any one <br />time. Sediment will be allowed to settle out in a sump area before <br />the water is pumped from the pits. <br />Water from phases 1 and 3 will be discharged into the Last Chance <br />Ditch and water from phases 2 and 4 will be discharged into the St. <br />Vrain Creek. Approval from the ditch company to pump water to the <br />ditch will be obtained. An alternate plan of dewatering <br />groundwater from mining phases 1 and 3, if permission is not <br />received from the ditch company, will be to pump water to the ponds <br />on property owned by weld County that lie to the east of the <br />subject site. <br />A NPDES permit will be obtained for all discharges to the St. Vrain <br />Creek prior to the commencement of mining operations. <br />
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