Unless you are a geotechnical or environmental engineer, or have similar reasons to be interested in such things, you tend not to think about what may be underground. You may know that sewers, pipes, and other utilities are down there. Underground oil storage tanks are also very common—sometimes undocumented and/or leaking. But what else might you find when you dig in the right (or wrong) place? Hart Crowser staff have been involved with projects where the following items were buried:
Cars. Squashed, in an old landfill.
Houses. Also squashed, with primarily the foundations and chimneys remaining.
Arsenic and lead from a historic glassworks factory. In the 1800s, toxic materials were used to color glass. The contaminants seeped into the soil, coloring it yellow, red, and black. This material was taken away so the property could be redeveloped.
Antique bottles and jars. Cold cream jars, cosmetic jars, medicine bottles, and others.
Burning coal. Thousands of underground coal fires are burning around the world right now. Since these fires can ignite spontaneously (by lightning) and burn for years, any exposed coal mine site is vulnerable.
Melted glass from the 1889 Great Seattle Fire. Fist-sized and iridescent, with impurities.
Skid Road Logs. In the 1800s, workers greased timber and slid it downhill to a sawmill in Seattle’s Pioneer Square. Some of these logs are in the fill in downtown Seattle.
A brick wall. While digging near Seattle’s Pike Place Market. The joke went:
“We hit a brick wall.”
“No, literally. We hit a brick wall.”
Golf balls. Found on the edges of a municipal waste landfill. One was a “gutta percha” ball dated just after the turn of the 20th century.
Petrified/fossilized wood. Found in a downtown Seattle excavation.
Medical waste. Needles, animal carcasses, and other appealing items found during a cleanup at a site on a river.