2014-10-27_HYDROLOGY - C1981014

• Permit No: C1981014
• IBM Index Class Name: Hydrology
• Doc Date: 10/27/2014
• Doc Name: Report by Dr. Corley, Potential Subsidence Impacts on Newlin Creek
• From: Dr. Corley
• To: DRMS
• Permit Index Doc Type: Other Surface Water
• Email Name: RDZ
• Email Name: MPB
• Media Type: D
• Archive: No

reconstituted with rip -rap and a layer of impermeable clay. Therefore, it is known that there is zero
alluvium in this portion of Newlin Creek above the impermeable layer.6
The indicated alluvium depths range from 0 to 35 feet. However, these drill holes are located on the
areas not eroded by the Creek, and the Creek flowline is considerably lower in the stream valley.
Therefore, the difference in elevation of the shoulder of the streambank and the flowline of the Creek
was measured at points along the Creek perpendicular to the respective drill holes.' Table 1 lists the
difference in elevations (streambank elevations). The probable flowline alluvium depth is listed as zero
when the streambed valley depth is greater than the drill hole alluvium depth since a negative alluvium
depth is meaningless.
Objective data utilizing exploratory drill hole logs for alluvium depth clearly shows that the alluvium
layer along the portion of Newlin Creek that is above the Southfield Mine is not avery deep layer; it is
essentially nonexistent.The data indicate that the alluvium has been eroded away by theformation of
the streambed valley. The only way to give more direct measurements would be to drill in the flowline
or to dig pot holes.
The EFCI statement that diminishing water flow in Newlin Creek has been occurring for many years prior
to the period in questionis directly refuted by EFCI's reports of creek flow at NC 2 and NC lsince 1999.
Table 2 summarizes this flow date for the years of reported flow in cfs.'If there was no flow of water at
NC 1,even ifthere was flow at NC 2, EFCI did not report flow amounts, therefore there are years missing
in the EFCI reports and Table 2.
Table 2Year
NC2(upper) NCI(lower)
1999
10.5cfs
9.5 cfs
2000
2.4
1.6
2004
7.8
7.8
2005
12.4
12.6
2007
10.8
10.7
2009
1.2
0.63
These flow measurementsindicate that the flow at NC2 and NCI were about equal for the reports of
1999 to 2007. Since 2007 there has been diminished flow at NC1. There was good flow at NC2 in the
years 2010, 2011, and 2012 that never reached NCI; maybe EFCI has records of flow at NC 2 for those
years, but that is unknown. The only other known record is from Janet Binn's inspection report of
March 27, 2012, that there was a flow 5 ft. wide and 4 in. deep at NC2 with no flow at the Thompson
driveway culvert.81f downstream observations could have been made at that time where the water was
disappearing upstream from the Thompson driveway culvert or on subsequent days there might have
been an independent record of where and how the water was running into the ground. There is
certainly a change in the last five years in the amount of water leaving NC 2 that has never reached NC
1, and that water has been observed by us and others to disappear quickly over a short distance and run
into the ground over the pillared areas of the Southfield Mine.
Precipitation for 1999 to 2014 is graphed in Figurel for total precipitation at Canon City.