2005-07-13_REVISION - M2000016 ‎(16)‎

• Permit No: M2000016
• IBM Index Class Name: Revision
• Doc Date: 7/13/2005
• Doc Name: response to adequacy review
• From: applegate group
• To: dmg
• Type & Sequence: AM1
• Media Type: D
• Archive: No

Applega#e ~
Gr®~~, Inc.
Mareh 11,2005
Ms: SuzanneJanzen
Lafage West, Inc.
10170 Church Ranch Way, Suite 200
Westminster, CO 80021
RE: Lafarge West, Inc., Riverbend Operation
Response to Adequacy Review
ll2c Permit Amendment Ol, Permit No.,M-2000- 6
Deaz Suzanne:
JUL 13 2005 `"~
DIvl3len of fei::;,:,,t. t Csclsrjy
The purpose of this letter is to 'provide you with responses to The Division' of Minerals and
Geology's ("DMG") adequacy review of-the ] 12c Permit Amendment to Lafarge West, Inc.
("Lafazge's") Riverbend Operation (Permit No: M-2000-016).. Specifically, this letter will
address unresolved issues from DMG's comments regazding Exhibits I), E and G in its adequacy
review letter .dated February 11; 2005. For clarity 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 and
commit to specific mitigation 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 ofeach 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 aze five
silt ponds identified in the reclamation plan. Each of these ponds will be reclaimed as wetlands,
and we will discuss the potential impacts from each in tum.
First, Ce112 in Phase .1 will be located on the east side of the South Platte River in the southeast
comer of the site. There are two wells located to the north and southeast from this pond that
could potentially be impacted by this pond. Lafage 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.'16352]), the lining of Cell.1;
which lies between Ce112 and the well, will have a greater impact on the water levels in the well.
The groundwater model determined the ultimate effect of the reclamation of the site on the well
7499. WesP1201b Avenue, Suite 200 (303j 452-6611 • Fax [phone]
Denver, Coloratlo 80234-2759 ~ - www.applegategroup.com