Site grading plan review
A checklist for reviewing civil grading plans for drainage, accessibility, and code compliance.
What a Grading Plan Shows
A site grading plan documents how the site is shaped, finished surface elevations, slopes, and drainage patterns. Grading drawings include existing contours, proposed contours, spot elevations at critical points, pavement and walkway slopes, drainage features (swales, inlets, area drains), retaining walls, and the relationship between the building finished floor and the surrounding grade.
Drainage Review
- Positive drainage away from the building on all sides (minimum 2% for 10 feet, then 1%)
- No ponding adjacent to the building foundation
- Sheet flow paths shorter than maximum length before being intercepted
- Swales sized for design storm flow with non-erodible velocities
- Inlets located at low points and along curb returns
- Area drains tied to storm system, not to sanitary
- Roof drainage discharge point splash blocks or piped to storm
- Downspout extensions per local code or convention
ADA Accessible Route Slopes
- Accessible parking and access aisles: 1:48 max in any direction
- Accessible route cross slope: 1:48 max
- Accessible route running slope: 1:20 max before ramp requirements apply
- Ramps: 1:12 max with landings every 30' of horizontal run
- Landings at top, bottom, and direction changes
- Curb ramp slopes and landing dimensions per ADA
- Detectable warning at curb ramps and street transitions
Pavement and Walkway Slopes
- Pavement minimum slope 1% for drainage
- Pavement maximum slope per use (drive aisles, ADA spaces, loading)
- Cross-slopes consistent with vehicular use
- Curb height transitions documented at every change
- Sidewalk cross-slope within ADA limit
- Slopes at building entries support landing requirements
Retaining Walls
- Retaining wall locations and heights consistent with grade differences shown
- Top of wall and bottom of wall elevations called out
- Wall types and design references (segmental, cast-in-place, soldier pile)
- Guardrails or fences at top of wall where drop exceeds code threshold
- Drainage behind wall (weep holes, drain rock, drain pipe)
- Geotech recommendations followed for wall design
Stormwater Management Coordination
- Detention or retention pond sized and located per stormwater report
- Outlet structure consistent with required release rates
- Emergency overflow path identified
- Water quality features (bioswales, raingardens, filters) sized per SWPPP
- Pre-development and post-development discharge rates documented
- Connection to public storm system designed and permitted
Erosion and Sediment Control
- Stabilized construction entrance shown
- Silt fence and inlet protection at perimeter and at low points
- Temporary sediment basin if disturbance exceeds threshold
- Slope stabilization for disturbed areas during construction
- Permanent vegetation establishment plan
- NPDES SWPPP referenced and consistent with plans
Trace water from the highest point on the site to the discharge point on paper. Every drop should have a continuous downhill path to a drain or to the property exit. Discontinuities along the path, flat spots, slopes the wrong way, drains at high points, usually indicate either a grading error or a missing drainage feature.
Coordination With Other Disciplines
- Finished floor elevation consistent across civil and architectural
- Underground utility depths compatible with grading and freeze depth
- Landscape mounding and planting beds consistent with grading
- Site lighting pole bases at correct top-of-foundation elevation
- Storm pipe inverts coordinated with structure footings and utility crossings
- Permit set grading matches stormwater calculations submitted to AHJ
Keep exploring
Related references for civil and site plan review.