A Boundary and Topographic Survey must be prepared by a professional land surveyor registered in the State of Washington. The ground survey and mapping shall cover the subject site plus an additional 25 feet immediately adjoining, and also include the full pavement section of adjacent streets for 100 feet in each direction of the site.
Standards
All land surveys submitted for land use approval shall state on the mapping Washington Coordinate System NAD83 (2011) - North Zone and NAVD 1988, as the “Basis of Bearings” and “Vertical Datum” respectively.
All lot corners shall be located and field tied to at least two City of Bellevue Survey Control Network monuments. Topographic elevations shall be referenced to City of Bellevue vertical control benchmarks. Survey Control Data Cards and Survey Benchmark Reports are available online or from our survey division (425-452-4385).
Include this mapping information:
- Legal description(s) of the parcels to be surveyed, verbatim from a current title report.
- North arrow and graphic scale.
- Sufficient geometry to accurately locate all lots, tracts, parcels, and easements.
- Recording numbers and a brief description of any easements, maintenance agreements, covenants, restrictions, etc., affecting the subject property.
- All existing structures with their locations indicated by measurements perpendicular to the property lines.
- Location, size, description, and top and invert elevations of all utilities. Field locate all visible appurtenances and use the best available information for buried utilities.
- Any lakes, rivers, streams, ditches, wetlands or ponds. Show the line of ordinary high water on lakes and the top-of-bank for streams and drainages. Show the 100-year floodplain, as shown on FEMA maps or as represented by the city in detailed studies, if available.
- Edge of pavement or curbs, curb cuts, sidewalks, wheelchair ramps, landscape areas, pedestrian or bike paths, rockeries, retaining walls, fences, bridges, culverts, etc. Show all concrete, asphalt or gravel-paved surfaces.
- Spot elevations at 50-foot grid; significant grade breaks; property corners; building corners; top and bottom of all walls and rockeries; center line, edge of pavement, and back of curb at 50-foot stations on all streets.
- Contours at 2-foot intervals for portions of the site with slopes less than 40 percent and for those areas exceeding 40 percent that will be graded; five-foot contours for portions of the site with slopes that exceed 40 percent but will not be disturbed. On flat sites with less than five percent slope, use one-foot contours.
Distinguish between areas of the site with slopes less than and greater than 40 percent. Identify the top of the 40 percent slope. Significant Trees: For commercial, multifamily, plat, short plat and planned unit development applications, show evergreen and deciduous trees, eight inches in diameter or greater, as measured four feet above existing grade. Label each tree with the common name and diameter. Show drip lines. If the site is heavily wooded, contact the Development Services Department to discuss reasonable alternatives. If critical areas exist on the site, identify their boundaries as required by the Land Use Code, including:
- Wetland boundaries as flagged by a wetlands biologist and subsequently surveyed. (Note: Boundaries must be approved by a land use planner prior to final survey.)
- Streams must have top-of-bank identified and surveyed. Top-of-bank is the point closest to the boundary of the active floodplain of a stream where a break in the slope of the land occurs such that the grade beyond the break is flatter than 3:1 at any point for a minimum distance of 50 feet, measured perpendicularly from the break.
- Areas of landslide hazard as identified and flagged by a professional geotechnical engineer or engineering geologist. Landslide hazard areas include areas of
- historic failure
- that have shown movement or are underlain by landslide deposits
- slopes that are parallel or subparallel to planes of weakness in subsurface materials
- slopes exhibiting geomorphological features indicative of past failures
- seeps indicating shallow ground water table on or adjacent to slope face
- potential instability because of rapid stream incision, stream bank erosion, and undercutting by wave action
- Coal mine hazards (Newcastle area) as identified by a mining engineer or engineering geologist.
- Flood Hazard Area must be identified based on 100-year floodplain shown in the FEMA map or as represented by the city in detailed site-specific or area studies.