COGCC and EnCana’s investigations of the gas seep in West Divide Creek continue. Since remedial cementing of the Schwartz 2-15B well on April 7, 2004, water sampling of the West Divide Creek seep has shown a dramatic decrease in benzene concentrations from the maximum concentration of 99 micrograms per liter (μg/l), which was detected on April 2, 2004, to non-detect on April 26, 2004. BTEX has not been detected in any of the weekly creek samples since late April, 2004.
On May 4, 11, 12, and 17, 2004 COGCC staff inspected the seep area and observed that the aerial extent, volume, and activity of the gas seep have diminished significantly, perhaps by as much as 90%, from the level of activity initially observed by COGCC staff on April 1, 2004.
BTEX has not been detected in any of the water samples collected by either EnCana or by the COGCC from the 47 water wells and springs currently being tested. Methane gas has been detected in many of these, but this is not unusual or unexpected because the water wells are completed in and the springs issue from the Wasatch Formation, which is known to contain gas bearing rocks. Samples have been collected from the water wells with greater than 2 mg/l methane for isotopic and compositional analysis of the gas. The results of the isotopic analyses indicated that the gas is not from the Williams Fork Formation and its presence appears to be unrelated to the gas that COGCC staff believes was released from the Schwartz 2-15B well. COGCC staff will be collecting additional gas samples from producing gas wells and water wells to obtain a more complete picture of the variability of isotope ratios and gas composition. EnCana continues to supply water to area residences, as requested.
A soil gas survey at residences near the seep has shown no impact of the gas release on any of these residences. A 24-hour Air Toxics sampling conducted on April 17, 2004 from sites along the West Divide Creek seep and adjacent residences, showed very low air concentrations of ethanol, hexane, cyclohexane, and heptane from some of the sites. None of the concentrations were above the health-based levels of concern.
On April 23, 2004, the COGCC staff issued a Notice of Alleged Violation (“NOAV”) to EnCana citing violation of COGCC rules regarding the improper cementing of the production casing on the Schwartz #2-15B well, the release of natural gas to West Divide Creek, failure to prevent the contamination of fresh water resources, and failure to notify the COGCC promptly of the cementing and bradenhead pressure problems in the well. The deadline for the NOAV corrective action was May 8, 2004. EnCana submitted their Form 27 Site Investigation / Remediation Workplan and their response to the NOAV on May 7, 2004. The Form 27 included EnCana’s April 9, 2004 workplan, the COGCC staff additions and modifications to the April 9, 2004 workplan, and additional work EnCana has undertaken.
EnCana has contracted with Colorado Mountain College’s (CMC) natural resources staff to conduct a biological study to monitor aquatic life in the West Divide Creek and to measure impacts, if any, to aquatic life from the gas seep. Data collection began on May 10, 2004 and will continue monthly through August 2004. Several residents in the vicinity of the seep are providing input to the CMC study.
The COGCC staff continues to provide updates regarding the West Divide Creek seep investigation to the Water Quality Control Division (WQCD) of the Colorado Department of Public Health and Environment (CDPHE) pursuant to our existing MOA. On May 13, 2004 a copy of EnCana’s Form 27 Site Investigation / Remediation Workplan was provided to WQCD for their review and comment.
The COGCC staff has prepared several informational updates for the West Divide Creek seep investigation. These are posted on the COGCC website and were distributed as handouts at the May 12, 2004 Energy Expo, held in Garfield County.
EnCana continues the moratorium on drilling and fracing activities within a 2-mile radius of the seep until COGCC approves resumption of these activities.