Williams testing results show benzene levels persist 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 June 25:
178.9 barrels or 7,514 gallons
Amount of contaminated water brought up with the hydrocarbons as of June 20:
Approximately 369,000 gallons
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.”