In late September 2006, the U.S. Environmental Protection Agency (EPA) began the removal clean up at the Helena Chemical Company facility (site) in Mission, Texas. The removal action involves digging up the contaminated soil within the on-site facility property underneath a deteriorating asphalt cap.
On December 1, 2006, an underground concrete sump was unexpectedly discovered on-site during soil excavation in Area 2. The concrete sump was situated at a depth of approximately 3 to 4 feel below the ground surface and measured 6 feet wide by 30 feet long and was 4 feet deep. Approximately, 1 foot of a dark colored liquid and sludge was observed in the underground concrete sump. EPA contractors immediately detected a strong odor and responded by applying a non-toxic liquid deodorizer to minimize the odor. OSC Leos directed EPA contractors to collect both liquid and sludge samples from the underground concrete sump for analysis of target compound list (TCL) volatile organic compounds (VOC) and semi-volatile organic compounds (SVOC), target analyte list (TAL) metals, and diesel range organics (DRO). A sludge and water sample was collected from the underground concrete sump and submitted to a fixed laboratory for analysis.
The odor from the underground concrete sump continued to emit a strong nuisance smell; therefore, OSC Leos directed the excavation to be discontinued on December 1, 2006. The area was covered and secured with plastic sheeting to reduce and/or eliminate additional nuisance odors. Upon further investigation on December 2, 2006, it was discovered that the underground concrete sump had cracks that allowed its contents to migrate and saturate the soil underneath. EPA contractors estimated the volume of potentially contaminated soil in the vicinity of the underground concrete sump to be approximately 8,000 cubic feet.
The final analytical results for the underground concrete sump was received on December 7, 2006 and revealed elevated concentrations of Alpha-BHC, Heptachlor, and Gamma-Chlordane in the sludge sample above the established Texas Commission of Environmental Quality (TCEQ) Risk Reduction Program (TRRP) Protective Concentration Levels. No elevated concentration of TCL VOC, TCL SVOC, TAL metals, or DRO were detected in the sludge sample. Final analytical results for the water sample taken indicated elevated levels of Aluminum, Arsenic, Iron, Lead, Manganese, alpha-cholordane, gamma-chlordane, heptachlor, and 1,2,3-trichlorobenze above EPA drinking water standards.
On December 4, 2006 EPA contractors safely removed and stockpiled contaminated soil and non-hazardous concrete from the concrete sump found in excavation Area #2. Excavation of contaminated soils continued in excavation areas #1 through #3. A depth of approximately 1 to 5 feet have been removed from each 25 foot square grid. Maps can be found online in the 'documents' section of this web site. The maps are labeled 'Primary and Secondary Excavation Maps.'
As of December 08, 2006 EPA has excavated and stockpiled approximately 2,500 cubic yards of soil for further analysis and waste characterization. To date, EPA has removed approximately 460 cubic yards of contaminated soil for off site transportation and disposal. Approximately, 57% of Area #1, 9% of Area #2, 55% of Area #3, and 4% of Area #4 have been confirmed by soil analysis to be below Texas Risk Reduction Program levels for commercial / industrial levels for all contaminants of concern.
Excavated soils are being stockpiled on Site for further analysis and waste characterization. A plastic sheathing is being used to cover all stockpiles and excavated holes on Site to minimize offsite migration of odors, dust, and the potential for contaminated storm water runoff. A frac tank has been mobilized on Site and will be used for containment and water quality sampling of any potentially contaminated storm water.
A network of air monitoring and air sampling devices have been deployed during evening and night hours in the neighboring community around the Site to ensure air quality standards are met. All data will be made available to the public immediately after a through laboratory analysis is completed. Air monitoring and sampling is also being conducted at excavation and stockpile areas on Site to ensure air quality standards are met.
To date, a total of 620 air samples of dust and vapors, 37 soil samples, and 4 water samples have been sent to an independent EPA approved laboratory for analysis since mobilization on site September 29, 2006. All pesticide levels on site and in the community have been below action levels of concern.
An EPA community office trailer is available on Site. A map which will have updated daily information on particulate air monitoring data is being posted next to the entrance of the office trailer for the public to stop by and view. This information will also be available in hard copy and electronic format. The office is open to allow community members an opportunity to speak with an EPA representative in person about any questions or concerns they may have about ongoing Site activities. This office has up to date and current information available in both English and Spanish.
Review soil analysis for waste profiling and characterization.
Approve transportation and disposal facilities proposals for the offsite disposal of contaminated soils. Based upon sampling results, contaminated soil will be properly disposed of in accordance with Federal and state guidelines.
Transportation and disposal of contaminated soil from Site.
Continue excavation of contaminated soil underneath asphalt cap.
Continue to conduct air monitoring and sampling on Site and in the community.
Continue off site transportation and disposal of contaminated soil.
Health and safety concerns have been raised about dust that may be potential contaminated migrating offsite during the clean up process.
An extensive network of air monitoring and air sampling safe guards are being utilize on Site and within the neighboring community. All scientific data will be quickly analyzed and made public for city and community leaders to review and discuss with the EPA. Dust control techniques are being used during soil excavation to reduce and / or eliminate offsite migration of dust.
EPA is committed to the public health and safety of its workers and the neighboring community. Results of the air monitoring and air sampling have indicated that the dust control measures taken are effective.
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