2011-12-28_HYDROLOGY - M1977300

• Permit No: M1977300
• IBM Index Class Name: HYDROLOGY
• Doc Date: 12/28/2011
• Doc Name: Notice of Violation, Amendment 3
• From: Cotter
• To: CDPHE-WQCD
• Permit Index Doc Type: Hydrology Report
• Email Name: AJW
• Email Name: TAK
• Media Type: D
• Archive: No

Whetstone'
Associates
To: Randy Whicker. (Cotter Corporation. N.S.L.)
From: Nathan Page. (Whetstone Associates)
Date: April26.2011
Subject: Material Volume Calculations for Potential Removal Action
1. INTRODUCTION
2. METHODS
34
Technical Memorandum
Cotter Corporation. N.S.L.. (Cotter) personnel collected soil samples from 35 locations at the
Schwartzwalder Mine for laboratory analysis of radium -226 and uranium in October 2010. The
work was conducted under Technical Revision 14 (TR 14) to the mine plan. The purpose of the
study was to detemiine zones of elevated radium -226 in the fill material that may require mitigation.
Using data provided by Cotter. Whetstone Associates performed 3D mapping of these zones and
calculated the material volumes. The purpose of this tech memo is to describe the methods and
assumptions used by Whetstone personnel in the 3D mapping and volume calculations for radium -
226.
2.1 Overview of Sampling Methods
A stratified soil sample set was collected at each sample location by Cotter personnel. Sample
depths ranged from the surface to the total depth of excavation (18 feet maximum). generally at 1
foot intervals. Eighteen sample sets were collected from the water treatment trench excavation (TR
series) to total depths ranging from 5 to 6 feet below ground surface (bgs) and 17 sample sets were
collected from various pit locations (DP series) to total depths ranging from 3 to 18 feet bgs. A total
of 183 soil samples were analyzed for radium -226.
In addition to sample collection. the water treatment pipeline trench excavation was traversed with a
hand -held gamma scanner providing a qualitative analysis of radium -226 levels in the subsurface.
The depth profile at each trench soil sample location was scanned. and a depth profile was scanned
at nine additional soil observation locations (TR -OBS series).
2.2 Generation of Sample Location Coordinates
The x -y coordinates of 35 soil sample points and 9 soil observation points were estimated from a
map generated by field personnel. Surface elevations were estimated using spot elevations from the
2010 elevation survey performed by Great Divide Consulting and contour lines from a 1990 mine
facilities map. Although GPS coordinates were collected for each soil sample and observation point.
the GPS accuracy level was unacceptable due to the steep canyon walls. Coordinates for each
sample location are shown in Table 1 and sample locations are plotted in Figure 1.
Whetstone Associates, Inc.
104 W Ruby Ave. • Gunnison, Colorado 81230 • Phone [phone] • Fax [phone]
4109C