APPCOR11407

• Permit No: C2006085
• IBM Index Class Name: Application Correspondence
• Doc Date: 10/19/2007
• Doc Name: Adequacy Review Responses Memo
• From: Mike Boulay
• To: Kent Gorham
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1373 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
INTEROFFICE MEMORANDUM
TO: Kent Gorham 'n¢,
FROM: Mike Boulay '°~
DATE: October 19, 2007
SUBJECT: Northfield Mine, Permit No. C-2006-085
Permit Application Adequacy Review Responses
COLORADO
DIVISION OF
RECLAMATION
MINING
- St-
SAFETY
Bill Owens
Governor
Russell George
Executive Director
Ronald W. Cattany
Division DireROr
Natural Resource Trustee
I have reviewed your Round #3 response letter to Environmental Alternatives, Inc. dated October
I8, 2007 in which you incorporated my recent comments on items 12a, 13a, 13b, ISa, 17a, I7b,
34, and 34a. I have the following remaining comments on Items 12a and 34. I concur with all of
your other responses in your October 18, 2007 letter.
12a. Derivation of the average hydraulic conductivity value was done using a crude estimation
method that is described in EPA's Ground Water Handbook, March 1987, p.80. It is
accomplished by multiplying specific capacity by 2,000 to get a crude estimate of
transmissivity. They did this correctly to arrive at an average transmissivity value of
12gpd/ft. But you are absolutely correct in your October 18 response in that they
miscalculated the average hydraulic conductivity value. Based on their data it should be
12gpd/ft = 50ft = 0.24gpd/ftZ. I agree with your response to them. You might consider
adding the following additional sentence to your comment. Please incorporate a
reference to the "industry standard rule-of--thumb methodology" used to estimate
transmissivity such as the EPA Groundwater Handbook, 1987.
34. You put together a good response to this item. I have the following minor suggestions.
Please consider adding the actual interval to be monitored by the SBWMW series of
wells. If appropriate add "above the ocean wave coal seam" to the discussion regarding
the appropriate location and stratigraphic interval (3rd page, top paragraph of your Item 34
response). Secondly, it appears that you are only requesting monthly water levels for
quantity purposes in the three SBWMW wells. However, our rules specifically require
quantity and quality parameters be measured for all aquifers potentially impacted.
According to 2.04.7(1) (v), the quality of subsurface water at a minimum should be
analyzed for TDS, pH, total iron and total manganese. Prior to disturbance is the only
timeframe from which to adequately obtain representative baseline water quality
information. Therefore, I would consider requiring seasonal sampling and analysis for
the minimum parameter list. As a suggestion, you could require that they analyze for the
Office of Office of
Mined Land Reclamation Active and Inactive Mines