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

Applegate
Group, ~~~.
Maz¢h 11, 2005
Ms: Suzanne,Jaozen -
Lafarge West, Inc. .
10170 Church Ranch Way, Suite 200
Westminster, CO 80021
RE: Lafarge West, Inc.,,Riverbend Operation ,
Response to Adequacy Review
112c Permit Amendment Ol, Permit No..M-2000-016
Deaz Suzanne:
- The purpose of this letter is to 'provide you with responses to The Division' of.Minerals and
Geology's ("DMG") adequacy 7eview of the 112c Permit Amendment to Lafarge West, Inc..
("Lafarge's") Riverbend Operation- (Permit No: M-20,00=016). Specifically, `this letter will
address unresolved issues from DMG's comments regazding Exhibits D, E and G in its adequacy-
- review letter dated February 11; 2005. For clatity we will .list each of DMG's comments
;followed by the respective responses.: `
9. The Reclamation Plan identifies five -cells and one existing pond that will be used for silt
storage and reclaimed as wetlands: Since these silt storage cells. have the potential. to act
as barriers to groundwater flow, the. applicant-must assess the potential impact mid
commit to speck mifigatiori measures:
The silt ponds identified in the reclamation plan will impact the flow. of groundwater surrounding ;
each pond by effectively lowering the hydraulic conductivity in the area:- Similar to the effects
on the groundwater flow in the vicinity of a lined pond, some increase in groundwater elevation, ,.
or mounding may occur on the up-gradient: side of each silt pond;.decreases in the elevation of
the groundwater table, .or shadowing,. may occur on the down-gradient side of each silt. pond.
Based on our review of the location wells:and other potentially effected structures in the vicinity
of the silt ponds, as well as our review. of the groundwater modeling previously completed for ,
the site, the effects on the groundwater flow.from these, silt ponds is negligible. There are five
silt ponds identified in the reclamatiomplan: Each of these ponds will. be reclaimed as wetlands,.
and we will discuss the potental impacts from each in turn.
First, Ce112 in Phase 1 will be located on the east side of the South Platte River in the southeast .
corner ofthe site: There aze two wells located to the north and southeast from this pond-that
could potentially be impacted by this pond. Lafarge controls the well located to the north.of the
• .pond, permit no: 13699; as such we will not consider the effects to this well. As;for the potential
. effects. to the well located to the southeast of the pond (permit no.' 163521), the lining of Cell. 1; .. -
,which lies. between Cell 2 and the well, will have. a greater impact on the water levels in the well.
- The groundwater model determined the ultimate effecYo£the reclamation of the site on the well
~- ~ 1499.West120ffi Avenue, Suite 200 ~ - ~, ~ - - -. .~ [phone] ~•Fax[phone]- •,'
Denver, Colorado 80234-2759 www.applegategraup.com