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Hidden Lake Emily
Northwestern Mutual’s neoclassical building on Wisconsin Avenue has an intriguing, hidden foundation – it sits atop a body of water called Lake Emily, named after an unknown person in the 1800s. Originally a cattail-filled pond about 8 feet deep that took up most of the block where the building now stands, the lake was drained and a foundation laid down for the building, completed in two stages in 1914 and 1932.
After digging a 20-foot-deep trench, thousands of pine logs were pounded into the ground with a pile driver, square concrete caps poured on top, then repeated with more layers of concrete, “almost like building a cake,” says Scott Wollenzien, Northwestern Mutual’s senior director for facility construction and operations. Water was pumped back in – submerging the logs was imperative to keep them from decomposing.
Most people expect to see a vast underground pool, but Wollenzien points out a small cap on the basement floor, unscrews it and shines a flashlight inside a hole. Looking down about 12 feet, you can see a ripple of water – Lake Emily. There are 74 similar holes throughout the basement. The only other evidence of the foundation is a crawlspace where you can see the concrete squares that top off the logs beneath.
Wollenzien says the water level used to be monitored by lowering a measuring stick into the holes, then adjusting the water level by using a garden hose. But in 2017, the company’s engineering team designed an electronic monitoring system. The city’s Deep Tunnel Project de-watered many properties, so about 5,000 gallons a week are pumped in to maintain Lake Emily’s levels. Few employees have been down there, but a plaque on the second floor commemorates the hidden lake below.
Subterranean Street Toilets
ON THE MEDIAN ISLANDS of Washington Boulevard at 53rd Street and near Wisconsin Avenue and 51st Street are rusty trapdoors that open to something unexpected. Concrete stairwells lead to underground rooms littered with debris. In the corner of each vault: an old toilet…