Wednesday morning, Mayor Jenny Durkan will be at Capitol Hill Housing’s affordable 12th Ave Arts building to sign into law the expansion of Seattle’s Mandatory Housing Affordability program into neighborhoods across the city including Capitol Hill. Wednesday night, a project to create some 350 new market rate apartments on First Hill will go before the design board for its first review.

While the timing of the eight-story project means its developer won’t be required to pay into the MHA pool — projects vested to a Land Use Code in effect before the upzones won’t be subject to the expanded program — the new development planned for 1100 Boylston will replace a surface parking lot with lots of new First Hill housing.

“The First Hill Neighborhood is an established, vibrant, urban residential community,” developer Carmel Partners and Encore Architects write. “The vision for this development is to enhance this community by creating a residential project that seamlessly blends into the existing neighborhood as a timeless and elegant design that will provide a comfortable place for residents and visitors.”

Carmel paid a pretty price for the parking lot land — it bought the three parcels making up the lot from the Polyclinic for $18.1 million last September according to county records.

The project is being planned under existing zoning to rise eight stories 240 feet — current zoning limits the area to 300 feet but the MHA upzones will push that to 440 feet — and will contain around 350 apartments and underground parking for 90 vehicles.

The developers say they are building smaller for a better transition to surrounding lower height limits.

“Although the site is zoned to allow for high-rise development, the project is designed as a mid-rise building,” they write. “This will allow for a graceful transition from the adjacent high-rise building to the nearby zones with lower height limits.”

That “graceful” transition also will make for a better neighborly relationship.

“The lower height also shows deference to the adjacent First Baptist Church, and responds to the community’s desire for a smaller scale building on this site,” the developers write.