Very good perspective on the spill in the Denver Post today. I included the highlights but the entire article is well worth reading. For those of you keeping track, please note the new number for the amount of contaminated groundwater siphoned from the spill – 369,000 gallons. Previously, as of May 31, the CDPHE had reported 225,000 gallons.
At least 1,500 cubic yards of petroleum-contaminated soil will be hauled from the oil and gas spill along Parachute Creek to Utah for final disposal.
The amount of contaminated groundwater siphoned from the spill, revealed in March, also is growing and has surpassed 369,000 gallons. While 155,000 gallons already was buried in a disposal well, 214,000 gallons currently in storage tanks will be treated on site and pumped back into groundwater along the creek, Colorado health officials said in response to queries last week.
Six months after the spill by Williams energy companies, which tainted the creek with cancer-causing benzene, the continuing cleanup and looming restoration work show a widening impact on resources. An underground plume created by the spill covers 10.6 acres and is still contaminating groundwater.
This spill was just one — and by no means the largest — of 179 oil and gas industry spills reported in Colorado this year. Most spills draw far less attention than the one along Parachute Creek.
But a review of Colorado Oil and Gas Conservation Commission data shows that 26 spills — nearly 15 percent — had a similar effect of contaminating groundwater. The data show that 15 spills — 8 percent — directly contaminated ponds and creeks …
Williams testing results show benzene levels in slight decline at the ever popular Sampling Site 6.
The maximum estimated size of the plume is approximately 1,500 feet long, 308 feet wide and 10 feet thick. This equals an area of approximately 462,000 square feet or 10.6 acres in area; roughly 34,595,000 gallons.
(The Glenwood Springs Hot Springs Pool is 405 feet long and 100 feet wide at the widest point, and contains 1,071,000 gallons of water.)
Chemical composition of plume:
Benzene; toluene; ethylbenzene; all three xylenes (M, O and P); cyclohexane; hexane;
methylcyclohexane; isopropylbenzene; acetone; bromoform; heptanes; 1, 2 , 3-trimethylbenzene; 1, 2, 4-trimethylbenzene; 1, 3, 5-trimethylbenzene and tetrachloroethene.
Amount of hydrocarbons extracted as of May 31:
173 barrels or 7,266 gallons
Amount of contaminated water brought up with the hydrocarbons as of June 20:
Approximately 369,000 gallons
Amount of contaminated sand and soil brought up with the above, same time frame:
Approximately 1,500 cubic yards
Groundwater benzene levels in mid-May from selected monitoring wells:
“Williams has draft groundwater results that show a significant decrease in benzene concentration in groundwater down-gradient of the aeration trench. The concentration of benzene in monitoring point TMP-48 dropped from 670 ppb on April 29 to 100 ppb on May 13 to 4 ppb on May 15. The benzene concentration in monitoring point TMP-52 dropped from 360 ppb on April 29 to 170 ppb on May 12 (the last sample collection date for TMP-52). Furthermore, the benzene concentration in the down-gradient air sparge trench and vertical well points efficacy monitoring location, SPT1-4, has decreased from 760 ppb on May 12 to 140 ug/L on May 15, 2013.”