PERMFILE61041

• Permit No: M2006018
• IBM Index Class Name: PERMIT FILE
• Doc Date: 5/19/2006
• Doc Name: Adequacy Response
• From: Gustavson Associates
• To: DMG
• Media Type: D
• Archive: No

c) accept a stipulation in the DMG permit acknowledging the above-mentioned items.
13. All of the surrounding ground water wells, with the exception of the two on the property,
are more than 600 feet from any planned mining and dewatering activity. In addition, they are
also all up gradient, Even the two wells on the site are up gradient from the planned operation.
Lafarge does not anticipate any long-term impacts to the hydrologic system or well owners.
Local draw down of the gravel aquifer will occur on the site and within a short distance off the
site. However, because of the up gradient hydrologic pressure and recharge, the drawn down
will be minimal off site. These are considerations that are addressed in the gravel well permit.
Lafarge would be pleased to provide a copy of this permit once the SEO issues it.
14 & 15. The alluvial aquifer is comprised of sand and gravel and overburden. From
Lafarge's test pits and borings, the aquifer is generally found at the overburden gravel interface
approximately 3 to 9 feet below the topographic surface depending on where you are on the
property. Between May and October, the level of the ground water raises due to leakage and
return flows from the neighboring agricultural ditches. The gravel layer averages approximately
18 to 20 feet in thickness. The maximum draw down of the gravel aquifer would be the 18 to 20
vertical feet of the gravel layer to the shale contact. Lateral draw down is estimated to be 200 to
300 feet maximum. In addition, the property owner has historically "flood imgated" the pastures
bringing the water level to the surface.
The wells are identified on EXHIBIT C sheet 1. The irrigation channels are also featured on this
exhibit. There are no springs on the property. The lower terrace (i.e. river terrace) is comprised
of wetland species of plants and wholly outside the planned mining disturbance area.
16. Lafarge does not cun'ently anticipate any long-term impacts. As with any dewatering
operation, there will be draw down of the groundwater aquifer locally. The property is bounded
on the south by the Colorado River; no changes are anticipated on the south side due to the water
gradient moving toward the river and the size of the river. Most of the local draw down will
occur on the north, east and west sides. On the east and west sides, very limited draw down will
occur due to the gradient being toward the river and any draw down would occur laterally. On
the north side, drawn down will be limited because the gradient is toward the pit and because of
the irrigation on the upper benches that recharges the ground water aquifer. Should the SEO
determine that there might be impacts, Lafarge will provide the DMG with the approved
mitigation plan per the gravel well permit as issued by the SEO.
6.4.8 EXHIBIT H -Wildlife Information
17. RESPONSE TO COLD DOW LETTER OF APRIL 13, 2006
With our beneficial land use as Rangeland, the reclamation plan in our application accomplishes
that goal. Several of the DOW's thoughts are incorporated in the operation standards and the
reclamation plan.
5757 Central Avenue ~ Phone [phone]
Boulder, Colorado 80301 GUSTAV50N ASSOUATES Fax: [phone]