Clients
Case Study
State of Washington and the City of Yakima, WA
Remediation of a former retail fuel location after a major leak from an underground storage tank.
The Challenge
The former Tiger Oil site in Yakima, Washington, presented severe environmental challenges after approximately 20,000 gallons of petroleum-related products were released from its underground storage tank system in 1981. Previously operated as a retail fuel station, the site experienced a substantial release of petroleum-related products, which impacted the surrounding soil and groundwater. Toxins found in the soil and groundwater included gasoline-range petroleum hydrocarbons and volatile organic compounds (VOCs). The impact extended beyond the site, affecting adjacent properties and posing risks to public health and the environment. The need for remediation was urgent.
Our Services
- Assessment & Planning Services
- High-Resolution Site Characterization
- Remediation Alternatives Analysis
- Stakeholder Support
Our Work
The State of Washington and City of Yakima engaged COLUMBIA Technologies to conduct a high-resolution site characterization of the property. Our work included:
- High-Resolution Site Characterization (HRSC) – to understand better the extent and behavior of residual petroleum contamination and its impact on groundwater conditions at the Tiger Oil site and adjacent properties. This included detailed 3D mapping of the residual hydrocarbon distribution and its interaction with the subsurface environment.
- Analysis of the Impact on Groundwater and Preferential Flow Paths – whcih outlines the detailed assessment of groundwater conditions, contamination levels, and the distribution flow paths of contaminated groundwater towards the adjacent property. This assessment included biochemical parameters to confirm the extent of the residual hydrocarbons and recovery of groundwater conditions beyond the contamination region.
- Measurement of Natural Source Zone Degradation (NSZD) – using two methods to confirm the natural degradation of the residual hydrocarbon mass: (1) A vertical profile measurement of biogenic gases above the hydrocarbon mass and (2) the measurement of the degradation rate by using the Carbon Isotope Analysis Methodology for 14C analysis developed by E-Flux (Ft. Collins, CO) for differentiating petroleum hydrocarbon-derived CO2 from that produced by natural soil respiration processes.
- Conceptual Site Model (CSM) Development – to integrate the data collected during the HRSC. This model provided a detailed understanding of the source of residual petroleum contamination, migration pathways, and potential receptors, guiding the remediation strategy.
- Remedial Alternatives Analysis and Recommendations – Developed a remedial action plan based on the HRSC and CSM findings. This plan outlined the specific actions to mitigate petroleum contamination, including treatment technologies and ongoing monitoring.
Key Results
COLUMBIA’s work produced a detailed understanding of the hydrocarbon contamination, effective recovery techniques, and comprehensive risk reduction measures and provided a clear path to restoring the site’s environmental quality and enhancing its value:
- Enhanced Understanding of LNAPL Distribution – The high-resolution site characterization provided a detailed and accurate mapping of the LNAPL distribution. Residual hydrocarbons at higher concentrations than expected were identified beyond the original treatment areas and at specific depth intervals. This enhanced understanding allowed for more targeted and effective remediation efforts in the future.
- Confined Groundwater Contamination – We accurately measured the groundwater contamination, and boundaries were confirmed within the extent of the adjacent property. We determined the optimal locations for groundwater monitoring wells for continued site monitoring.
- Comprehensive Conceptual Site Model (CSM) – The comprehensive CSM integrated the data collected during the high-resolution site characterization – providing a clear understanding of the residual hydrocarbon source, migration pathways, and potential receptors and guiding the remediation strategy and ensuring its effectiveness.
- Confirmed and Measured Natural Source Zone Degradation (NSZD) – Serves as a benchmark against which future remediation efforts can be compared.