Parachute Creek spill: Day 47

Screen shot 2013-04-03 at 6.39.35 AM

The green dots are water wells along Parachute Creek. Williams Gas Processing Plant is located in the upper left corner — the uppermost red circle

Latest news —

Amount of benzene in Parachute Creek declines with distance from leak
State, feds continue monitoring leak investigation

Parachute Creek aerated to rid water of benzene detected after spill

Benzene near Parachute leak is monitored, still within limits [subscribers only]

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COGCC update – April 22, 2013

Here is an update on the situation at the Parachute Creek gas facility.

Ongoing sampling continues to detect benzene at trace levels at the same three sampling points where it was first detected last Thursday (4-18).

Here is a summary of detections since the last update on Friday. The sample points, as outlined in the update last Thursday, are at 1,800 feet, 2,500 feet and 3,700 feet, respectively, from the above-ground valve set where a leak of natural gas liquids was found in March. These samples were analyzed on site using a field gas chromatograph.

Sample point CS6: 3.1 parts per billion (Saturday), non-detect (Sunday), 3 ppb (Monday)

Sample point CS7: 1.5 ppb (Saturday), 1.4 ppb (Sunday), no result available (Monday)

Sample point CS8: 1.1 ppb (Saturday), 1.2 ppb (Sunday), no result available (Monday)

The state drinking water standard for benzene is 5 ppb. Since Parachute Creek has not been designated as a drinking water supply by the state Water Quality Control Commission, the actual benzene standard on the creek is 5300 ppb to protect aquatic life.

Sampling at three more points downstream of those detections did not detect benzene. Samples for benzene taken at the point where the town of Parachute diverts water for its irrigation supply 2.7 miles downstream of the gas facility continued to show no detection of benzene.

Operators continue construction and installation of equipment to address benzene in surface water. That work includes building an interceptor trench to strip benzene from groundwater prior to the point where it’s believed groundwater enters the stream. Two other in-creek systems are designed to strip benzene from the surface water.

Operators have drilled several additional monitoring wells to determine the extent of impacted groundwater. These new monitoring wells are not detecting benzene, an indication that delineation of the affected groundwater continues to improve.

The COGCC, the Colorado Department of Public Health and Environment and the U.S. Environmental Protection Agency all remain engaged in developments at the site and are in communication with one another, and with operators.
[end of update]

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In case you missed the maps and other stuff yesterday —

Potentiometric Surface Map 4-16-2013

Sample Locations thru 4-19-2013 with Property Boundaries

Benzene Concentrations in Groundwater & Isoconcentration Map 4-19-13

Email Correspondence Re: COGCC Approval for Response Actions

Email Correspondence Re: COGCC Approval Aquifer Testing Procedure

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