This is how Ganjapreneur reports the development

Under Washington state law, marijuana businesses must be located at least 1,000 feet from sensitive public gathering spots such as parks, libraries and schools. Seattle’s new zoning laws have reduced that to 500 feet, though the larger buffer still applies to schools and playgrounds.

A 1,000 foot buffer also applies to I-502 retailers that are in close proximity to one another. According to Councilmember Tim Burgess, that limits most neighborhood business districts to having only one cannabis retailer, each. In an attempt to undermine the black market and grant tourists easier access to legal cannabis, however, the buffer between retailers was reduced to only 250 feet in Belltown and other parts of downtown Seattle.

For cannabis growers and processors — who are often considered to be less noticeable and intrusive than actual retail pot shops — the buffer between cannabis businesses has been reduced to 250 feet.

Under the new regulations, the total real estate available to cannabis businesses in Seattle has increased by 1,600 acres.

http://www.ganjapreneur.com/seattle-changes-zoning-laws-allow-marijuana-businesses-places/