Glossary
The words behind the build.
A plain-English reference for the construction, zoning and transit terms that come up across this guide.
- Mixed-use
- A building or block that combines more than one use — here homes, a hotel, offices, retail and a daycare — rather than a single purpose.
- Podium
- The wide, lower base a tower (or towers) sits on. At Onni 606 a shared 7-level podium carries retail, amenities and parking beneath all three towers.
- Superblock
- An unusually large city block. The ~4-acre Onni 606 site spans 106th Ave NE between NE 4th and NE 8th.
- Topping out
- The milestone when a building's highest structural element is placed — i.e. it reaches full height, before the facade and interiors are finished.
- Excavation
- Digging out the site for the below-grade levels. At Onni 606 crews will dig five below-grade parking levels across nearly the whole block.
- Shoring
- Temporary walls and bracing that hold back soil and protect neighbors while a deep hole is excavated.
- Mass excavation
- Large-scale earth removal for an entire site's foundation, as opposed to digging narrow trenches.
- Below grade
- Below ground level. Onni 606's parking and back-of-house levels (P1–P5) are below grade.
- Slab
- A flat, structural layer of concrete — e.g. the floor of each level or the foundation mat at the bottom of the excavation.
- Curtain wall
- The non-structural exterior 'skin' of glass and metal panels hung on a tower's frame.
- Floorplate
- The footprint/area of a single floor. Office towers use wide floorplates; residential point towers use smaller ones.
- FAR (floor area ratio)
- A zoning measure of total building floor area relative to lot size — it caps how much can be built on a site.
- Design Review
- A City of Bellevue process that evaluates a project's appearance, massing and public realm before approval.
- Master Development Plan (MDP)
- The overarching, city-approved plan governing a large multi-building project like Onni 606.
- SEPA
- Washington's State Environmental Policy Act — the environmental review a major project must complete.
- Light rail (2 Line)
- Sound Transit's 2 Line, which opened across Lake Washington in 2026; its Downtown Bellevue station is a few blocks east of the site.
- The Grand Connection
- Bellevue's planned landscaped pedestrian spine linking downtown to the waterfront and Wilburton; Onni 606 dedicates a 30-ft-wide segment of it.
- Public plaza
- Privately built open space dedicated for public use — here a 15,000-square-foot plaza at the south end of the block.
- DNTN-O1 (Downtown Office 1)
- Bellevue's most intensive downtown land-use district, where the city's 2017 Downtown Livability code set a 600-foot maximum height over a base floor area ratio of 5.0. The Onni 606 block sits in this district.
- Amenity incentive system
- Bellevue's zoning mechanism (Land Use Code 20.25A.070) that grants bonus floor area and height above the base in exchange for public amenities such as open space, through-block connections and weather protection — the route by which a downtown project reaches the 600-foot ceiling.
- Secant wall
- A shoring wall built from a row of overlapping bored concrete piles, used to hold back soil and groundwater during deep excavation. It is the kind of system used to dig the five below-grade levels at Onni 606.
- Determination of Non-Significance (DNS)
- The outcome of a SEPA environmental review finding that a project is not likely to have a probable significant adverse environmental impact. Onni 606 received a DNS with its 2022 approval.
- E-VCP (Expedited Voluntary Cleanup Program)
- A Washington Department of Ecology program in which a property owner cleans up a contaminated site under Ecology oversight on an accelerated track. The 606 block is enrolled as E-VCP No. XN0011.
- Contained-in determination (CID)
- An environmental-cleanup determination of whether excavated soil holds regulated contaminants above set thresholds, which governs how that soil must be handled or disposed of. CID soil characterization at 606 is scheduled alongside demolition.
- PCE (tetrachloroethene)
- A dry-cleaning and metal-degreasing solvent and the main contaminant at the 606 site. It reached the block as a dissolved groundwater plume from a former dry cleaner across NE 8th, not from any on-site use.
- Plume clause
- A provision of Washington's Model Toxics Control Act under which a landowner is not a liable party for contamination that merely migrated onto its property from an off-site source. Onni invokes it for the PCE plume beneath 606.
- Environmental covenant
- A deed restriction recorded on a property's title that limits future use to keep residual contamination safe — at 606, barring water-supply wells, making the parking garage a protective 'cap,' and requiring long-term groundwater monitoring.
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