REP37462

• Permit No: C1980003
• IBM Index Class Name: Report
• Doc Date: 3/3/1997
• Doc Name: 1995 ARR & AHR Response Letter
• From: TERRAMATRIX
• To: DMG
• Annual Report Year: 1995
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

[~ ~~ Mr. Joe Dudash
~~ February 27, 1997
Page 2
results are given. In the response to the Division's adequary question no. 8 for the 1994 Annual
Repos, TerraMatrix stated that these parameters would be included in post-1996 water quality
analyses. Please explain why these parameter could not be tested in 1995.
Response: The above mentioned parameters were not tested in 1995 due to the fact chat
the CDMG review of the 1994 Mnual Reclamation Report was received by TerraMatrix
on November 30, 1995. The field tests for dissolved oxygen and turbidity were
incorporated into the 1996 field monitoring regimen with the following results:
Date Site Dissolved Oxygen Turbidity flemarks
Img/II
4/16/96 LHG 8.46 N/A No field turbidity due to
problems with
4/16/96 UHG 8.71 N/A instrument
5/13/96 LHG 5.94 N/A No field turbidity due to
problems with
5/13/96 UHG 6.21 N/A instrument
5/13/96 HG-8 7.38 N/A
FALL 1996 All sites N/A N/A No field D.O. or
turbidity due to
problems with
instruments
The instrument problems have been resolved and the field measurement of dissolved
oxygen and turbidity will be performed for all future monitoring events.
5) In Exhibit 5 of the 1995 Annual Report, for the groundwater monitoring Feld data resrdts, the
depth to water for well HG2 changed from an average of about 90 feet in ]994 to an average of
about 49.5 feet in 1995. Please provide a discussion of what TerraMatrix believes is tl~e reason
for such a dramatic change.
Response: Please find attached, in Exhibit B, two (2) graphs illustrating the depth to water
in wells HG1 and HG2 from November 1987 to November 1996. It should be noted that
average annual depth to water is not the most appropriate measure of change because it
doesn't reflect seasonal variation. As can be seen from the graphs, water levels in well HG2
have historically shown much greater fluctuation than HGl and a 40+ foot seasonal
increase from fall to spring has been previously observed. We believe that the change
observed between 1994 and 1995 is consistent with this trend and is a resuh of an unusually
dry year during 1994 and an especially wet winter and spring of ]994/1995. The total
precipitation measured at the Hayden Weather Station during ]994 was 12.21", well Below
the 30-year average of 16.94" annually. In April, May and June 1995 alone there was 85"
of precipitation. This heavy precipitation following a previously dry year would produce
a substantial recharge to the groundwater system in the area and would account fora 40+
foot increase in the water level in well HG2. The pertinent data from the National
Weather Service in Hayden, Colorado is attached in Exhibit C.
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