What grading and drainage covers, and when a property manager needs it
Grading and drainage is work on the shape of the ground and the route water takes off it: cut, fill and compaction to a finished grade, the fall away from a building's walls, and the drains, inlets, pipe and basins that carry what lands on a site to an approved point. The California Building Code asks for the ground next to a foundation to slope away from the building, and accepts a swale or another approved way of diverting water where a lot line or an obstruction leaves no room.
A property manager needs the work when water stands against a wall or a dock door for days after a storm, when an inlet has silted up or a trench drain has lost its grate under truck wheels, when a lot ponds because the grade dropped rather than because the surface failed, when a retention basin has silted in and no longer holds what it was built to hold, or when a pad for a building or a lot expansion needs earthwork before anything is paved. Each is a different scope, and the request reaches any of the 32 cities served.
The work is performed by a licensed and insured contractor assigned to the request, who contracts with you directly. Every job leaves the same record: the grades before and after, photographs of the drains as they were built, the water test and the permit sign-off.
Grading and drainage sub-services available across the Central Valley
Why grading and drainage is needed in Central Valley buildings
On ground this flat, water goes where the grade sends it. Most of the service area has little fall, so a small settlement, a raised landscape bed or a blocked inlet is enough to hold water against a wall. The answer is rarely a bigger pipe: a fall that runs, a swale where the fall cannot be had, and an outlet the water can reach.
The rain arrives in one band, and that is when the ground is tested. The NOAA 1991 to 2020 normals for the Modesto airport put 9.85 of the year's 12.27 inches between November and March, with July and August at almost nothing. Drainage faults show in those five months and are best walked then; earthwork, basins and site work run in the dry ones, when fill can be compacted.
A large paved area sends a lot of water to very few openings. Tilt-up warehouses and truck yards drain acres of paving into a handful of inlets and the trench drains at their dock aprons, so a broken grate or a silted channel leaves water at the doors. Where a grate sits on a walking route, the 2010 ADA Standards allow no opening that passes a half-inch sphere, with the long dimension across travel.
Digging is regulated before the first bucket, not after it. Government Code 4216.2 has the dig area marked in white and the notification center told at least two working days ahead, with nothing opened until every operator has responded and the ticket renewed by its 28th day where work runs on. Calling 811 starts that, and it applies on private property where a buried line is known to run.
Past an acre of disturbed ground, the state's stormwater permit comes in. The State Water Board's construction stormwater program covers grading and excavation, and a project disturbing one acre or more needs coverage; the owner arranges that and the pollution prevention plan before work starts, and the crew assigned to the request works to it. Restoring a drain to its original line, grade and capacity is routine maintenance, outside the permit.
How grading and drainage is delivered
A site visit is arranged with the contractor assigned to the request, ideally in wet weather. Site visit scheduled at a time that suits you. Start date set in the written estimate. Where water stands, the falls at the walls, the inlets and the discharge point are recorded.
The dig area is delineated in white before the notification goes in, and no bucket moves until every operator has marked its line or answered that it has none. Within ten feet of a high priority installation the operator meets the crew on site first.
A grading permit comes from the building official unless the work is exempt. The owner's approved plans, any soil report and the stormwater coverage are in place before work starts.
A trench of five feet takes a protective system, spoil stays two feet back, and walks and paving are supported before they are undermined.
Unsuitable material is stripped, fill is placed without organics or oversize rock and compacted in lifts, and the backfill at a foundation allows for later settlement. The finished grade is cut to falls that run to the outlets.
French drains are built on clean gravel with the pipe bedded and the trench wrapped, trench drains and inlets are set in concrete, and the system discharges by gravity or pump to an approved point.
The finished falls are checked, water is run through the new drains to prove they take it, and bare slopes are stabilised before the final inspection. The building official signs the work off, and the owner receives the grades, the photographs and the permit record for the file.
What you receive on every drainage job
A grade is approved by people who were not standing on the lot in the rain, so what the ground does is measured, photographed and written down.
Grading and drainage by city
Each city page covers the lots and low ground in that city, where its storm water ends up, the office that issues the permit and the sub-services asked for most. Modesto is the base, and its page takes the city area by area.
Grading and drainage questions from Central Valley property owners
Enough that water leaves the wall instead of standing against it. The building code requires the ground immediately next to a foundation to be sloped away from the building over a set distance, with lower minimums for a swale and for paving inside that band. Where a lot line, a wall or another obstruction leaves no room, the code accepts a swale or another approved way of diverting the water.
A trench of clean gravel with a perforated pipe in it, wrapped so that soil does not clog the stone, collecting water in the ground and carrying it to a discharge point. The building code describes that detail as the foundation drain used at basements and below-grade floors, not as a rule for every wet yard. On a slab-on-grade building, regrading or a surface inlet may move more water for less digging.
On private property that needs no excavation permit, the law says an excavator may contact the notification center where the property is known, or should reasonably be known, to contain a buried line. A commercial site almost always has services crossing it, so the ticket is opened, the area is marked and the crew waits for every operator. Grading is excavation under the same article, so a machine cut counts as much as a trench.
When the project disturbs one acre or more of soil, or disturbs less than an acre as part of a larger common plan of development that reaches one acre. The owner arranges the coverage and has the pollution prevention plan in place before work starts, and the crew assigned to the request works to it. Maintenance restoring a facility to its original line, grade and capacity is not construction under the permit.
Not more of it than ran there before. The grading appendix of the building code, where a city has adopted it, holds drainage across a property line to what existed before the grading, keeps excess or concentrated flow on site or sends it to an approved drainage facility, and asks for the discharge area to be protected against erosion. A new drain is routed to an approved point, not at the fence line.
The San Joaquin Valley air district's earthmoving rule covers construction, demolition, excavation and other earthmoving, and holds visible dust to 20 percent opacity. Sites are pre-watered and worked in phases, unpaved haul roads are watered and posted at 15 miles an hour, and disturbed ground left unused is stabilised. On the larger sites the rule names, a dust control plan goes to the district and is approved before work starts.
The owner. Where the building official asks for a grading plan or a geotechnical report, both come from the owner, and the work is built to those approved plans and to what the building official requires. Stormwater coverage and the pollution prevention plan sit with the owner in the same way. A request through this platform does not obtain a permit, prepare a plan or provide engineering.
Related trades on the same lot
Guides on documenting damage
Service area from the Modesto base
Typical time from the Modesto base to a property in each city, by road, when a site visit is booked. Fog in December and January and harvest truck traffic on Highway 99 and Highway 132 can add 15 to 30 minutes.
Windows are planning figures from the fulfilling contractor's dispatch records and are confirmed with a time when the request is acknowledged. [CLIENT to confirm]
