Breaking news: Benzene bubbles up in monitoring wells

Benzene levels high near Parachute Creek

Benzene from gas plant leak polluting groundwater near Parachute Creek

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Bob Arrington responds to the March 28 COGCC update [below]

Bob Arrington is a retired engineer and the Battlement Mesa citizen representative on Garfield County’s Energy Advisory Board (EAB). He also represents the Grand Valley Citizens Alliance and the Battlement Concerned Citizens.

Bob says:

A losing stream, or influent stream, is a stream or river that loses water as it flows downstream. The water infiltrates into the ground recharging the local groundwater, because the water table is below the bottom of the stream channel. This is the opposite of a more common gaining stream (or effluent stream) which increases in water volume farther down stream as it gains water from the local aquifer. Losing streams are common in arid areas. (Wikipedia definition)

Latest report from COGCC says, hydrologists working the problem have ascertained that the water table is below the stream bottom in this area (they did not define the extent and it could be a localized anomaly). Which means stream water is going into the water table to maintain a point that is below stream bottom. If this is an aquifer being replenished, it becomes important whether this surfaces further down Parachute Creek and flows into the Colorado River or continues below stream beds to surface further downstream in the Colorado valley.

We do know that the geology of the area shows that formations rise to the West and the Colorado has cut through them. As you come out of DeBeque Canyon, the Williams Fork formations deep in the Parachute area form the majestic Book Cliffs high above Grand Junction, 40 miles away.  If the aquifer is confined to the creek delta and banks then it is likely to surface at the confluence of the Colorado with a deeper bottom.

In any case, this makes the problem even a worse case scenario because the plume spreads and floats the greater volume of hydrocarbons atop the water table allowing longer subsurface flow and a longer soluble exposure/mixing of the BTEX’s. Now their current remedy is a slow washing of a tainted area by gravity flow of hydrocarbons to a trench trap that MUST be deeper than the top of the water table and continually being filled with water to at least hose nozzle depth. Currently, this has cost over 150 thousand gallons of water that will be soon required for irrigation needs.

Even with this technique being used, the report shows benzene up to 3600 times allowable levels beyond the trenches. These trench traps, unless taken to the bottom of the aquifer, will still allow the soluble BTEX’s to flow with the balance of groundwater. This newest evaluation does not improve the situation, if anything it makes it worse as plume routing spreads and becomes harder to trace.
[end of Bob Arrington’s response]

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March 28 Update from COGCC spokesman Todd Hartman (CO Dept. of Natural Resources):

Operators have sampling results from several groundwater monitoring wells drilled between the recovery trench and Parachute Creek. Three monitoring wells, to the southeast of the trench and roughly 30 feet from the creek, showed significant groundwater impacts.

Monitoring wells showed benzene at a range of 5,800 parts per billion to 18,000 ppb. The monitoring well with the highest concentration (18,000 ppb) is nearest to the recovery trench and current area of source investigation. These levels are significantly above the state health standard for benzene of 5 ppb. Operators are currently drilling another set of monitoring wells roughly 10 feet from Parachute Creek to further delineate groundwater impacts.

To date, numerous samples of surface waters in Parachute Creek, including samples taken by the Colorado Oil and Gas Conservation Commission, have shown no evidence of contamination. Both the COGCC and consultants for the operators have analyzed groundwater elevation data and find that Parachute Creek is a “losing stream” in this area, which means the creek serves to recharge groundwater, as opposed to groundwater feeding the creek. Hydrological consultants for the operators concluded this to be the case from data gathered March 22 and March 27.

In addition, pumping from the recovery trench is enhancing groundwater flow away from Parachute Creek. Since the onset of this event two weeks ago, operators have removed 4,200 barrels of groundwater and 142 barrels of hydrocarbons.

Operators continue the investigation for a source of this release, working around a valve box for a pipeline carrying natural gas liquids away from the gas plant

COGCC continues an intensive, ongoing field presence at the location since first responding to reports of affected groundwater on March 15. COGCC and the U.S. Environmental Protection Agency are participating in daily conference call briefings with Williams and WPX, and providing oversight and direction.
[end of update]

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One Comment on “Breaking news: Benzene bubbles up in monitoring wells”

  1. Leslie Robinson Says:

    In addition to water further downstream, are the workers getting tested for Benzene chemical impacts, especially those who were out in the field before the respirators were made available?

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