2010-10-21_REVISION - C1982057

• Permit No: C1982057
• IBM Index Class Name: REVISION
• Doc Date: 10/21/2010
• Doc Name: Seneca II-W SL-03 Inspection Memo
• From: Jim Stark
• To: Dan Mathews
• Type & Sequence: SL3
• Email Name: DTM
• Email Name: JRS
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
COLORADO
D IV IS I ON OF
RECLAMATION
MINING
SAFETY

INTEROFFICE Bill Ritter, Jr.

Governor
MEMORANDUM Mike King
Executive Director
Loretta E. Pineda
TO: Dan Mathews Director
FROM: Jim Stark
SUBJECT: Seneca II-W SL-03 Inspection
DATE: 21 October 2010
The following are my observations from the Seneca II-W Partial Phase I Bond Release
SL-03.
Data Collection: - All of the data used to confirm the post-mining topography and
permanent, post-mining drainage channels was collected with a Trimble GeoXT and
Trimble Terrasync. The data was analyzed with Trimble Pathfinder Office 3.1 and ESRI
ArcMap 9.3. The Division also reviewed Seneca II-W permit information including
Exhibit 20-2 (engineer certified 28 August 2007 with TR-59 and 12 May 2010 with TR-
68), SL-03 Exhibit D (engineer certified 9 July 2010), Exhibit 20-5.9, sheet 1 (engineer
certified 30 January 2006 with PR-05), Exhibit 20-5.9 sheet 2 (engineer certified 28
August 2007 with TR-59) and Tab 20, Attachment 20-1 - Post-mining Drainage Channel
Design (revised May 2007 with TR-59).
- Prior to collecting data on 21 and 22 September 2010, an elevation correction point was
taken. The elevation correction point is taken at a known, surveyed point on the mine site
and used to correct all of the elevation data collected by the GeoXT. The point the
Division used was Seneca II-W survey point 3008, which is shown on Inspection Map 3.
The known elevation at this point is 8076.82 feet. The Division's measured elevation at
this point was 8036.2 feet. This gives a correction of +40.62 feet for all of the Division's
measured elevation points.
Backfilling and Grading: - The Division created three cross-sections in the reclaimed
Seneca II-W South area to assess the post-mining topography as it is constructed versus
the approved post-mining topography shown on Exhibit 20-2. These cross-sections are
shown on Inspection Maps 1 and 2. Cross-section A-A' runs along the PM-3 drainage
area, beginning at the edge of the disturbed area and ending north of pond 016A. This
cross-section runs from east-northeast to west-southwest. Cross-section B-B' runs from
south to north along the PM-2 drainage area and bisecting the PM-1 and PM-3 permanent
post-mining channels. This cross-section begins at the south edge of the disturbance, just
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