Summer sinkhole: a Philly history lesson

A few days ago, I was excited to receive from my friend Canelón an eventbrite link to a talk offered for free by the Philadelphia Water Department with historian Adam Levine about the hottest topic of West Philadelphia in the past month: The Sinkhole.

Let me back up a few weeks.

On June 4, 2019, @dhimmel and I encountered an obstruction on Baltimore Ave on our way to work. The road had been closed off for couple blocks. The biker ahead of us stopped and asked me if I knew what was going on. I of course had no idea. The next day, on the way back from our morning run we got to witness this:

I later learned that what was happening had to do with the Mill Creek Sewage system. Much later, I learned (from the talk) that the problem actually came from intercepting pipes that feed into the Mill Creek sewer, not the main sewer itself. People started calling this a "sinkhole", which, having a Geology degree, I had a problem with. The local favorite Clarkville even had a sinkhole pizza party.

Anyhow, that is why West Philly residents have been discussing this topic nonstop. Daniel and I have taken our two out-of-town guests Marshall and Lelchuk to visit this uniquely historical landmark, gazing down into the abyss. That is also why we immediately registered for the Mill Creek history talk that was also live streamed (kudos to USciences for such an amazing live streaming production).

First off, Adam Levine (no - not the one with many tattoos) is a fascinating speaker. We loved him so much we had to get an autograph:

I honestly wished all my history lessons have been taught like this. I laughed a whole lot but also learned so much!

Levine started off the talk describing how the city was built and why it involved burying streams and sewers. He used a waffle and a waffle iron to illustrate the elevation discrepancy between pieces of property and streets when they have been raised up or carved down. I learned that water accumulating at the bottom of the depression (where the syrup goes) is where people dispose of things, and how this results in the implementation of stream burying and combined sewers.

Now, while combined sewers of sewage and stormwater has its advantages, they cause a serious problem in rainy days when there is excess amount of runoff that has to bypass the treatment plant and discharge directly to the Schuylkill river (pronounced /skookil/). To reduce the amount of overflow, since 1998, the city has created green landscapes that filter and consume rainfall such as porous pavements, rain garden and rooftop garden. My architect sister who studied urban design would have loved these neat structures.

I got to see so many cool photos, drawings and paintings from the 1800s of adaptive stairways to main door, huge constructions being jacked up, and stream diversion for sewer build. I learned that the word miasma means bad odor and was once thought to cause infectious diseases.

Okay, now onto the sinkhole. Why? What happened?

It turns out that man-made things can't last forever. In the past, there have been huge collapses of houses above the sewer lines, resulting in serious injuries and even deaths. The city eventually had to buy out houses along the sewer lines and made roads on top of them instead. On June 4, 2019, however, it's actually only part of pipe connecting to the manhole directing to the big sewer that was washed out and took the soil with it, creating a void underneath the paved road. After 130 years of service, the pipe finally caved in (get it?!)

As much as I complain about the streets of Philadelphia and their potholes, I have to commend the city for detecting this fatal issue and fixing a gigantic hole in only 20 days.

Levine ended his enlightening talk with some fun social events that went on, including the ritual offerings with trending hashtag #allhailsinkhole. Someone wrote on their Facebook wall: "If you stand close, you can hear the rushing waters cleansing away the regret of the city".

Regret or not, I'm happy that the incident gave me a chance to participate in a very West Philly-like event and learn more about the city of brotherly love.

Select photos from the talk slides

Levine at an outfall.

A book cover by Joseph E.B. Elliott.

Ice-cream lost in the sewer. 2000 qt engulfed.