For the past ten weeks I have been interning with a small environmental consulting group in Seattle called the Pacific Groundwater Group. Consulting is a vague term, so when I tell people about my internship I often get head nods and “oh, that’s cool,” followed by a brief pause and “wait, what do environmental consultants do?” The answer depends on the company, but, as its name would suggest, PGG works primarily on issues related to groundwater issues. The staff at PGG have extensive backgrounds in areas such as hydrogeology and geochemistry, and the projects they work on can range from determining where to build drinking water wells to designing remediation strategies for polluted sites.
I spent the majority of my internship working on a project that was a little outside of PGG’s normal wheelhouse as it did not have to do with groundwater, but instead with landfill gas. Landfill gas is the mixture of gases that are produced in landfills, primarily through bacterial decomposition of organic material in trash. The subject of this project was Genesee Park and Playfield: a roughly 60-acre park located on Lake Washington in southeastern Seattle. Today it looks like any other park, but only a few decades ago, from 1947 to 1963, it was a landfill taking in garbage and other refuse from the southeastern portion of Seattle. After 26 years of waste filling, the landfill was covered in several feet of sandy cover sediment and then developed into a park. In the mid-1980s, the Seattle-King County Department of Public Health conducted soil gas sampling at Genesee which revealed the presence of high levels of methane in the ground. While methane is not toxic to humans, it can be explosive (or an asphyxiant) if present in high enough concentrations. This is especially a concern at Genesee because the park is surrounded on almost all sides by homes where methane could potentially collect and become dangerous.
My supervisor, Jeff, and I planned to repeat the methane sampling that was conducted in the 1980s, compare the new data to the old, and then present our findings to the Seattle Parks Department. However, before we got out to the park to look for methane quite a bit of preparatory work had to be completed. This included historical research, learning to use GIS programs, determining our experimental procedure, safety training, and applying for a permit to sample at the park. With help from the Parks Department and many people at PGG, we were able to sample at Genesee over three sunny days in mid-July. To measure methane content in the soil, we employed the “bar-hole” method, which essentially consisted of pounding a steel rod three feet into the ground, taking it back out, and then immediately inserting a gas monitor to obtain a reading of methane content. In total Jeff and I repeated this process 41 times, which left me sore, tired, and at one point, standing in a Safeway parking lot looking through the window of a locked car door at my car keys on the driver’s seat. Nevertheless, after a few weeks of processing and analyzing the data we collected, I presented our findings to an assorted crowd from Seattle Parks, PGG, and Seattle Public Utilities. In broad strokes, we found that in many places around the park, the amount of methane detected using the bar hole method has decreased enormously since the 80s, but in a few locations it has increased. The length of my internship, combined with my lack of expertise in the topic of landfills, did limit our ability to provide specific explanations and other analysis for our observations, but the data we did collected will certainly contribute to decisions made regarding Genesee going forward. Furthermore, over the course of this project I have learned a great deal about working in a professional environment, designing a scientific investigation, and presenting technical findings to an audience.