2005-03-14_REVISION - M2000016

• Permit No: M2000016
• IBM Index Class Name: Revision
• Doc Date: 3/14/2005
• Doc Name: Adequacy Review Response
• From: Lafarge West Inc.
• To: DMG
• Type & Sequence: AM1
• Media Type: D
• Archive: No

~LAFARG E
NORTH AMERICA
Construction Materials
expected groundwater impacts. The Groundwater and Surface Water Evaluation Before During
and After Riverbend Mining Operations has identified two wells that may potentially be
impacted by our mining operations, well number 2216 owned by John Norris and well number
13697 owned by Tom Holton. A waiver will be obtained by these well owners prior to mining
within 600-feet of their wells; the well owners will negotiate preferred mitigation measures. The
concerns and rights of well owners in the azea will be addressed in more detail by the Office of
the State Engineer through the gravel well permit application process.
12. The applicant needs to describe how the drawdown of the pits and any
shadowing/mounding effects will impact the structural integrity of the surrounding wells,
surface water drainages, activities which rely on groundwater in the vicinity of the site,
and vegetation on or near the site (including the cottonwood trees in the riparian area
near the South Platte River and the wetlands located adjacent to the pits). The applicant
must also describe any mitigation measures to be implemented and trigger points that
would put mitigation measures into effect.
Please see enclosed "Groundwater and Surface Water Evaluation Before During and After
Riverbend Mining Operations" which describes the anticipated impacts from the drawdown of
the pits. The cottonwood trees in the riparian azea neaz the South Platte River will be preserved;
dewatering water will be discharged through pipes that are perforated in the portions adjacent to
cottonwood groves located within 200 feet of the river corridor. Impacts to the wetlands, both
jurisdictional and non-jurisdictional, will be addressed in the Corps 404 Individual Permit
currently under draft.
13. The Division has concerns that there may be effects on the amount of water conveyed in
the Fort Lupton Bottom Ditch, the Brighton Ditch, and Big Dry Creek due to dewatering
of the pit. The applicant must project the amount of water that will be lost from these
structures if these structures leak and ground water level around the structures is
lowered as a result of mining activities. The applicant needs to indicate whether this
issue has been investigated and the results of that investigation.
Please see enclosed "Groundwater and Surface Water Evaluation Before During and After
Riverbend Mining Operations" which details anticipated impacts resulting from dewatering
activities. Please refer to Response #4, which explains how dewatering activities will not occur
adjacent to the ditches prior to agreement execution.
14. Due to the potential for permanent impacts to ground water, the applicant may need to
take permanent mitigation measure such as installing French drains. The applicant
should consider this eventually and respond to this concern.
Please refer to attached response prepazed by Applegate Group, Inc.
LAFARGE NORTH AMERICA INC. -Lafarge Aggregates, Concrete & Asphalt
10170 Church Ranch Way, Suite 200 Westminster, Colorado 80021
Telephone: [phone] Facsimile: [phone]