North Trunk Sewer Line

 

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Prior to the southern extension of the North Trunk Sewer Line to Pine Street there was no sanitary sewer in Madison Park.  Sewage was mostly piped into Lake Washington with the hope that lake water would dilute it to a safe level. A “Bathing Beach” on the southern border of what would become Edgewater Park Apartments had a sewage outfall on both ends of the swimming area. At that time Madison Park had few real houses but there were many rental cabins leased out by the McGilvra Estate.  If Madison Park was going to become the upscale neighborhood that developers aspired it to be houses would need toilets that didn’t flush into where the home owners went to swim.

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The building of Lake Washington Blvd in preparation for the 1909 Alaska Yukon Pacific Exposition funneled more people onto Madison Street and hence, Madison Park Real estate would be purchased, houses would be built and toilets would flush into a sewage system that was yet to be completed.

Reginald H. Thompson had designed an oversized sewer system for the city so that we wouldn’t have to dump into the lake but instead into Puget Sound at West Point.  Getting all of the parts and pieces connected took a while and when Madison Park had to have it there was a solution.  Running through Madison Park in its 48” diameter glory the North Trunk Sewer Line upsized to 54” near McGilvra School and then upsized again to 60” where it turned to cross the Puget Mill Company land that would soon become Broadmoor.  Then upsizing to 66” and running east in line with Lynn Street it encountered a ravine that cradled Arboretum Creek, the high-water marsh of Willow Bay and Lake Washington Blvd.  What to do? 

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Enter architect Walter Ross Baumes Willcox.  Borrowing technology from Ancient Rome, in 1911 he designed an aqueduct to carry the 66” pipe full of smelly upper crust goo over the ravine and turned it into the scenic Willcox Footbridge that is a Montlake icon and the bane of any vehicle over 9’ tall.  Once across the aqueduct, err footbridge, the pipe upsizes to a magnificent 90” diameter, makes a right turn on 24^th Ave and heads north out of Montlake. 

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 It's often asked why the Willcox Bridge wasn’t built with more clearance and you must remember that Lake Washington Blvd. was designed as a “pleasure drive” and not an arterial at a time when motor vehicles had only been in Seattle for ~11 years, were scarce and commercial traffic wasn’t allowed to drive on it.  There was no need for it to be any higher

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Luckily it was built like a tank out of steel reinforced concrete.  The brick is just a lovely veneer that adds no strength to the structure.  The 66” sewer pipe is really a large u-shaped trough covered with a concrete walkway.  Multiple trucks, buses and trailers over 9” have roughed it up and always come out second.  Like a Timex watch the Willcox Bridge takes a lickin’ but keeps on tickin’.