ACTIVATED CARBON BASED SOLUTIONS FOR SPILLS IN REMOTE AND DIFFICULT AREAS

INTRODUCTION Environmental calamities such as tanker truck crashes and pipeline leaks do not always occur in well populated areas. Tanker truck crashes can occur on remote mountain passes or lonely stretches of highway. Pipeline leaks can occur in distant areas of open range or other isolated locations. Treatment of these spills requires the ability to clean up the contamination with very few standard resources. Often these sites will not have access to electricity or cellular service and just getting to the location of the spill can require a long drive from the nearest town. These restrictions can often limit treatment options to those that can be completed quickly and without needing long term access to the site. The remediation of petroleum fuels spilled during several tanker truck roll-overs will be discussed below, along with the obstacles presented by each site and the innovations needed to complete the remediation.

ASSESSMENT AND REMEDIATION OF A LIGHT NON-AQUEOUS PHASE LIQUID HYDROCARBON PLUME IN FRACTURED BEDROCK

INTRODUCTION During the extension of an access road on the Canadian Forces Base (CFB) Esquimalt in Colwood, British Columbia, a black, viscous, liquid hydrocarbon product was observed oozing from newly exposed bedrock fractures in the roadside. Road excavation was subsequently halted to undertake assessment and remediation of the hydrocarbon product. The exposed bedrock was dammed with sawdust, a geomembrane barrier was installed and the area was backfilled until an appropriate course of action could be determined. The site location is shown in Figure 1. The property boundary and key site features are shown in Figure 2; the hydrocarbon seep is shown in Figure 3. Bunker C oil is a heavy-end (high molecular weight) hydrocarbon product that has a specific gravity slightly less than water and is therefore a light non-aqueous phase liquid (LNAPL). The source of the LNAPL was inferred to originate from a decommissioned fuel depot located approximately 100 m distance uphill from the road, where 40,000 barrels of Bunker C fuel oil were historically stored in one of three, large above-ground storage tanks (ASTs). A Bunker C oil spill reportedly took place at the tank farm more than two decades prior; however, the spill volume was unknown and initial investigations found no evidence of contamination between the roadside LNAPL occurrence and the former AST. Furthermore, there was also anecdotal evidence that an historic asphalt manufacturing facility may have operated in the vicinity of the access road. A hydrocarbon product similar to Bunker C is used in the manufacture of asphalt. The source and extent of the LNAPL and the potential migration pathways to the roadside location were therefore unknown. When an LNAPL spill occurs in the subsurface, the LNAPL can migrate downward under gravity through the soil pore space in the unsaturated zone. When LNAPL encounters the ground water table (the top of the saturated zone), it tends to spread out laterally because it is less dense than water and will migrate primarily in the direction of the water table gradient (water table slope). However, when LNAPL encounters bedrock, the direction of LNAPL migration can become much more complicated depending on the degree and orientation of bedrock fractures that control its movement. When fracture density is sufficiently high and the fractures are interconnected, contamination is able to migrate down-gradient through the bedrock in the same manner as through unconsolidated materials. However, when dominant structural features are prevalent that favour specific orientations, preferential pathways are created that can result in the cross-gradient migration of LNAPL. This paper presents a case study for the assessment and remediation of LNAPL in bedrock at the Canadian Forces Base (CFB) Esquimalt (the site). Geological mapping of bedrock structural features has long been used by the mining industry to identify key structures associated with economic zones of mineralization and to predict the location and extent of mineralized targets. In a similar regard, to effectively remediate LNAPL within fractured bedrock requires the identification and characterization of any structural features that might be controlling the preferential migration of LNAPL within the subsurface to other areas of the site. A significant amount of surface outcrop is present at the site and this was recognized as a cost-effective opportunity to complete a geological assessment of the bedrock. A geological mapping program was subsequently undertaken to assess bedrock outcrops for fracture density, fracture aperture, the orientation of primary fracture sets and lithologic contacts. The area was also inspected for larger scale structural features such as faults, deformation and erosional features that might influence contaminant migration. Fracture sets and lithologic contacts were mapped by outcrop location, and fractures with visible LNAPL were mapped separately from those without LNAPL. The geological data collected was used to construct stereographic projections of structural planes on a stereonet. Poles to structural planes were plotted and colour-coded by area and by presence/absence of LNAPL. The plots were then analyzed individually, and as a composite plot, to identify the dominant preferential pathways controlling LNAPL migration at the site. By superimposing these features on areas where LNAPL was observed, LNAPL delineation targets were effectively identified and the plume was subsequently delineated with confidence and remediated.

USING PASSIVE ULTRASENSITIVE HYDROCARBON DETECTION TO ELUCIDATE NASCENT PIPELINE LEAKS: A COLUMBIA PIPELINE CASE STUDY

Underground and above ground hydrocarbon transport pipelines often contain carbon dioxide (CO2), hydrogen sulfide (H2S), water and chlorine which cause corrosion. Corrosion often begins as pinpoint leaks that expand over time. These leaks are often difficult to detect using conventional methods until a major event occurs. Pressure testing can determine a leak to be present, but does not pinpoint the location of the leak. Pipeline pigs normally only detect leaks after they become significant and costly. The use of methane detectors has also been utilized with the recent popularity of drones. However, the use of airborne methane detectors has been less than successful due to the limited linear range of the methane detectors and poor sensitivity. Passive ultrasensitive sorbent modules have been used to detect nascent leaks at parts per billion ( ppb) levels, which is 1,000 times more sensitive than traditional methods. Passive ultrasensitive sorbent modules contain a specially engineered oleophilic (i.e. oil loving) adsorbent encased in a microporous membrane. These membrane pores are small enough to prevent the entrance of soil particles or water, but are large enough to allow hydrocarbon vapor molecules to pass through and concentrate on the adsorbent material within. The result is a 1,000-fold increase in concentration allowing for ppb level detection. The Columbia natural gas condensate pipeline case study took place in 2007 just southwest of Pittsburgh and involved a pipeline buried at a depth of approximately 6 ft. Ultrasensitive passive modules were installed at the surface above the pipeline. A battery operated hand drill was used to drill a 1 inch hole in the ground to an approximate depth of 3 ft. The module was inserted into the hole, covered with dirt, and left for 4 days. After retrieval the modules were analyzed by thermal desorption/mass spectrometry. The objectives of the survey were to: examine potential fingerprints for evidence of gas condensate leakage, determine if nascent leaks could be distinguished from baseline readings, compare results with pipeline maintenance records for ground-truthing purposes. The results of the project showed: several locations along the pipeline exhibited strong potential as leakage points, the results were validated with a known leak along the pipeline, the data helped to monitor the efficiency of prior pipeline repair work, baseline levels of hydrocarbons were statistically derived from the data, potential nascent leak points were identified along the pipeline.

DUST MITIGATION EMPLOYING A PROGRAM BASED APPROACH

INTRODUCTION Of all the natural resources being taxed by the needs of the mining and oil & gas industries, possibly the most important is the expanding demand for water resources. As water becomes scarcer, and increasingly important, new technologies are needed to find innovative ways to preserve this precious resource. In Chile, for example, the mining industry is investing billions of dollars to build desalination plants and pipelines; bringing ocean water as far as 200 kilometers inland to meet demand and maintain operations. It is a wide-ranging crisis for that nation and a top priority for their government and economy. It has been reported that water managers in 40 states expect water shortages in some portion of their states in the next 10 years.1 In the U.S., as more and more communities continue to be built, greater requirements on the current water infrastructure is generated. Water demand is projected to increase by 55% globally between 2000 and 2050. The increase in demand will come mainly from manufacturing (+400%), electricity (+140%) and domestic use (+130%). In the face of these competing demands, there will be little scope for increasing water for irrigation.2 For 25 percent of people and operations that rely on water from aquifers, this source is being consumed at a rate that will create significant problems meeting the demand in as few as two generations.3 There are three major areas of water usage for dust control in mining and oil & gas industries: material handling (process), non-traffic areas (wind erosion), and traffic areas (roads and large surfaces). Each of these areas could have an article dedicated to dust mitigation solutions; however, the one area that all mine and oil & gas facilities have in common is the unpaved haul road and light vehicle access road. This article will focus on controlling dust on the drivable surface and will show that implementing a dust mitigation program will not only save water resources, but also can become a source for expense savings.

REHABILITATION OF HISTORICAL UNDERGROUND MINE WORKINGS—A PHASED APPROACH

INTRODUCTION Rehabilitation is essential in legacy mines as mine hazards do not improve with time; they will always get worse. Most hazard mitigation techniques address immediate risk but do nothing to actually fix the problem. The current impetus is to move away from simply identifying and managing risks and towards long-term solutions that eliminate the hazards in a planned way. This article will describe a proven approach to identify and eliminate hazards in such a way as to preserve the positive legacy of mining while eliminating issues that affect the environment and communities in proximity to legacy mine sites.