Site grading plan review
Helonic is an AI construction drawing analysis platform for teams researching site grading review during drawing review.
A checklist for reviewing civil grading plans for drainage, accessibility, and code compliance.
What does a grading plan show?
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.
What should a grading drainage review catch?
A drainage review traces every high point downhill to a drain or outfall with no trapped low spots.
- 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
What ADA slopes apply on a grading plan?
ADA routes on the grading plan are limited to 1:20 walking slope and 1:48 cross slope unless they are ramps.
- 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
What pavement and walkway slopes are allowed?
Pavement and walks need enough slope to drain and not so much that driving or walking becomes unsafe.
- 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
What should retaining-wall grading details show?
Retaining-wall grading details should show top and bottom of wall, drainage, and the finish grade against the wall.
- 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
How should grading coordinate with stormwater?
Grading must deliver design flow to inlets, ponds, and outfalls shown on the stormwater plan.
- 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
How do you check erosion and sediment control against grading?
Trace water from the highest point on the site to the discharge point and confirm a continuous downhill path.
- 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.
How should grading coordinate with other disciplines?
Grading must match finished floor, utility covers, and landscape spots so nothing fights the slope.
- 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.