New Amazon buildings in the Seaport will have to be built to survive days like today

The new Amazon tower proposed for the Seaport - and a second one that it might have built next to it - would sit on a lot that is prone to flooding and is full of hazardous chemicals left over from its days as a rail yard.

WS Development cites the expensive costs of hardening the buildings against rising sea levels and removing all the contaminated soil in its application to the BPDA for both permission to put up the towers and to get a total of at least $5 million and possibly $10 million in tax breaks over 15 years.

WS, which is erecting the large Seaport Square complex, would put the buildings on what is now one of the South Boston waterfront's last big parking lots, on Congress Street between Boston Wharf Road and East Service Road. In its filing, WS says Amazon has agreed to take most of the space in a 17-story building - with an option to put up a second, similar building on the site. The buildings would have room for up to 2,000 employees apiece.

WS cites these new jobs in its requests for the tax breaks, saying the buildings will help it pay for roughly $20 million in improvements to the area, including new nine acres of open space in a neighborhood that sprouted without much of it, and a new entrance for the Courthouse Silver Line stop and dedicate bicycle lanes on Summer Street and Boston Wharf Road.

But WS also spends a fair amount of space in the document discussing how expensive it will be just to develop the land - just a short walk from Seaport Boulevard, which became part of Boston Harbor in the Jan. 4 storm:

[D]ue to the increase, and the anticipated continuing increase, in sea level, and the increased severity and frequency of storms predicted due to global climate change, additional and costly improvements are needed to prevent the flooding of the proposed structures and ensure that the proposed structure and its systems are appropriately protected from the effects of global climate change and flooding from sea level rise. The specific measures required to protect the Block L4 Building [the first Amazon building] from flooding due to sea level rise and global climate change represent significant cost premiums over conventional construction and include measures such as: builrup ground floor elevation and ramp/building entry configurations; upper-level placement of the building's electric utility vault, requiring expensive structural, HVAC, and life safety systems, location of major building systems on upper floors and/or the roof of the building, requiring longer runs of main utility services, the installation of enhanced emergency building systems designed to increase resiliency and survivability, and the installation of rapidly-deployable flood barriers around the building in the event of a storm event. ...

The grade of the L4 Building will be elevated to be over 2 feet above the 500-year floodplain to maximize resiliency and adaptability to climate change and sea level rise. Key electrical, mechanical, and other building infrastructure will be located above the ground level to further enhance the building's resiliency. The L4 Building will also include numerous other environmentally sustainable features, including rainwater harvesting, a high-perfomance exterior façade, and high-efficiency HVAC and other building systems; a LEED v4 Silver rating will be targeted for the L4 Building. All of these aspects of the L4 Building's design add substantial cost to the construction of the building's structure and systems.

WS filing (25M PDF).