Save The Arkansas River: Report confirms need for multi-pronged, multi-site fix

Report confirms need for multi-pronged, multi-site fix
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Save The Arkansas River on 21 February, 2008
 
Date: January 30, 2008
To: Stan Christensen, Mike Wireman, US Environmental Protection Agency
CC: Brad Littlepage, USBR LMDT , Doug Jamison, Lee Pivonka CDPHE WQCD
From: Jord Gertson, SourceWater Consulting
Subject: California Gulch, CERCLA Site, Ground Water Elevation Update
On January 14th - 18th, 2007, I downloaded, calibrated, and compiled the ground
water elevation data for for the following wells: DWWOB1, LDT36+77, LDT46+66,
LDT75+05, LDT96+44,BMW5, OU6MP-ELK, OU6MP-DW2, NW5A, AP1TMW13D, AP1TMW7,
AP1TMW18, NW8A, NW13AR, and UMW19. The dataloggers have not been replaced in
wells NW5D, NW5C, WCCPZ1, or WO3 due to wells overflowing with water. Four
pressure transducers lost power during the most recent deployment, including
locations, NW8A, NW5A, BMW5, AP1TMW18, and UMW19. Since the initial deployment
in June 2004 we have collected 1.95 million water level measurements using
Insitu pressure transducers. I could not access BMW3 recently, due to massive
snow storage on top of the well casing.
I have included several plots of ground water elevations in this memo for your
reference. A plot of the upper LMDT wells, another of the lower LMDT wells, A
plot of the potentiometric surface near the LMDT and a series of plots that
reference the lower California Gulch alluvial wells.
Listed below are a few highlighted characteristics of recent ground water
levels:
Peak mine pool water levels appear to flatten in November and December, which
indicates a relief to recharge. This relief occurred when the water elevation of
the OU6 mine pool exceeded the elevation of California Gulch near the Yak Surge
Pond (10147.00 ft. asl).
Several wells and springs near the Yak Surge Pond continue to discharge into
California Gulch. Recent analysis indicates that discharge at the Gaw Shaft has
increased 50% and Valentine Shaft discharge has increased 40% in 2007.
Prior to January 2005, the Canterbury Tunnel was discharging more that 620 gpm.
Prior to January 2005, none of the wells in California Gulch near the Yak Surge
Pond were flowing.
Like a switch, when water levels between the Canterbury Tunnel and The LMDT
rose above 10147.00 ft. asl, wells, springs, and shafts began to flow near
California Gulch.
As discharge increases from wells, springs, and shafts in California Gulch the
Canterbury Tunnel discharge is less than 240 gpm, more than 61 percent less than
previous measurements in 2005. The current tunnel discharge is less than 82
percent of the original discharge from the tunnel.
Historically, the Canterbury Tunnel de-watered a portion the LMDT mine pool.
Without this water level relief, the LMDT mine pool will continue to rise until
additional relief points are achieved.
Recently, residences near the Canterbury Tunnel have abandoned use of their
potable well water due to high concentrations of iron.
The water elevation currently (January, 2008) in LDT46+66 is 75 ft. (23 meters)
higher than the Canterbury Tunnel portal.
The average water elevation of the LMDT Mine pool is approximately 188 feet (57
meters) above the LMDT portal invert.
Five wells below the Yak Tunnel surge pond continue to overflow into California
Gulch, they include, WCCPZ1, WO3, NW5D, NW5C, and the GAW Shaft.
AP1TMW7 appears to be influenced by flow at the GAW alluvial well and by water
levels in Strayhorse Gulch. Recently, the water elevation at BMW3 surpassed the
water level in AP1TMW7, reversing the mine pool gradient towards the Gaw Shaft.
The water elevation in OU6MP-DW2, LDT 96+44, LDT75+05, LDT46+66 and the Robert
Emmet Shaft appear to indicate a flat continuous mine pool.
Expect the OU6 mine pool to rise another 10 - 15 feet higher (> 10160.00 ft.
asl) in late summer and early fall of 2008. Expect higher regional ground water
levels and more ground water to discharge into California Gulch in 2008.
In Summary, recent water level increases in the OU6 mine pool appear to be
influenced by a reduction in discharge from the Canterbury Tunnel in 2005. There
has been no significant increase in average annual precipitation in the last 8
years.
Yet since January 2005, the OU6 Mine pool continues to gain extensive volume.
Historically, the Canterbury Tunnel provided a sink for the OU6 Mine Pool
recharge It appears that the LMDT Mine pool has lost this beneficial drain and
water levels will continue to rise and discharge into California Gulch and
possibly Iowa Gulch.
It is also evident that the LMDT mine pool water elevations are higher than the
land elevation at the base of the Yak Tunnel Surge Pond. The mine pool has risen
beyond this elevation, and may be discharging into California Gulch. The LMDT
Mine Pool will rise above this elevation significantly in 2008. We may begin to
see water quality changes from the wells that are overflowing (WCCPZ1, WO3,
NW5D, NW5C and GAW) or other springs. There are several springs and seeps in the
vicinity of the Yak Surge Pond and Apache Tailings are that should be identified
and quantified immediately.
The upper portions of the LMDT appear to be overwhelmed with recharge, causing
the mine pool to overflow to California Gulch. Losses from the LMDT mine pool to
California Gulch may already be occurring. Further analysis of the
potentiometric water surface near the Canterbury Tunnel, Yak Surge Pond, and Yak
Tunnel Portal should be evaluated immediately to avoid significant risk to
receiving natural resources.
These are some of the observations that I have made during my investigation and
update of existing water levels. Please feel free to contact me with any
questions or comments regarding this data.
[ILLUSTRATIONS TO FOLLOW]