What Drainage Support Work Do We Handle?
Drainage support is the earthwork and excavation scope that sets up a drainage system to function correctly. We cut, grade, and shape — landscape contractors, plumbers, or drainage specialists install pipe, rock, and filter fabric. We coordinate closely with whoever is completing the downstream work to make sure grades and dimensions are right.
- French drain trenching — cutting the trench, placing drain rock and perforated pipe, backfilling
- Surface swale grading — shaping a shallow, sloped channel to carry surface water away from structures or low spots
- Daylighting — extending drain pipe to a visible discharge point at the slope face or property edge
- Rear yard regrading — correcting negative slope toward foundations, patios, or structures
- Slope correction — reshaping cut or fill faces to direct water away from property improvements
- Driveway drainage grading — cross-crown or water-bar shaping to prevent driveway channeling
- Berm construction — small raised earth features to redirect sheet flow
- Pre-construction drainage grading — rough drainage established before pads, slabs, or structures are placed
What Does Drainage Work Cost in Northern California?
Drainage earthwork is priced by scope, not by the hour. French drain trenching and swale grading are the most common scopes we see. Costs below are for the earthwork — pipe, filter fabric, drain rock, and inlet/outlet structures are priced separately by the drainage contractor if they're not part of our scope.
- French drain trenching: $25–$60 per linear foot for cut, drain rock, perforated pipe, and backfill
- Surface swale grading (cut/shape only): $1,500–$5,000 for typical residential rear yard
- Rear yard regrading to correct ponding: $2,000–$8,000 depending on area and cut volume
- Daylighting trench to slope face: $500–$2,000 depending on run length and terrain
- Berm construction: $1,000–$3,500 for small residential berm to redirect sheet flow
- Slope correction on cut/fill face: $1,500–$5,000 depending on face height and extent
- Drain rock: typically $50–$80 per ton placed for French drain backfill
- SWRCB Construction General Permit: required for projects disturbing 1 or more acres — includes SWPPP documentation requirement
Sacramento Valley Drainage — Why It's Different Here
Sacramento gets about 17 inches of rain per year — most of it between November and March, often in concentrated events. Valley floor soils are heavy clay in many areas, which means slow percolation and surface ponding during wet years. Foothill properties face different problems: steeper grades, faster runoff, and seasonal springs that appear after significant rain.
- Valley floor (Sacramento, Elk Grove, Woodland, Davis): heavy clay soils — French drains perform best in gravel lenses; surface swales often faster and more cost-effective
- Foothill properties (Auburn, El Dorado Hills, Grass Valley, Placerville): faster runoff on slopes, more erosion risk, seasonal seeps common near cuts
- Seasonal performance: drainage systems sized for dry-year rainfall will be overwhelmed in wet years — size for the 10-year storm, not the average
- Foundation drainage: negative grade toward a structure foundation is a chronic source of moisture intrusion, especially in older homes with no subfloor drainage
- New construction: drainage must be established at rough grade — fixing drainage after the patio, deck, and landscaping are in costs 3–5x more
- Agricultural parcels: irrigation runoff adds to stormwater load — factor into drainage design on working farms and orchards
French Drains vs. Surface Swales — Which One Solves the Problem?
Both French drains and surface swales move water — the difference is where the water travels. French drains handle subsurface water and slow the ponding that happens when soil saturation builds up. Swales handle surface sheet flow. On many sites, the fix requires both. Getting the right approach saves money and avoids re-doing work.
- French drain: best for subsurface water, soil saturation around foundations, and areas where surface grade can't be changed
- Surface swale: best for directing sheet flow away from structures, correcting negative slope on larger areas, and driveway drainage
- French drain limitation: perforated pipe can silt up in heavy clay over 5–10 years without filter fabric — spec the right fabric at installation
- Swale limitation: requires space to cut and grade — not usable in tight side yards or areas with existing improvements
- Combined approach: swale to collect surface flow, French drain to handle subsurface saturation — common on foothill cut lots
- Discharge point: all drain systems need a legal discharge location — daylighting to a slope face, storm drain connection, or drainage easement
Related Services
Grading
Prepare land for pads, driveways, drainage, ADUs, shops, garages, and future construction.
Trenching
Drainage, utilities, irrigation, conduit, and site prep trenching support.
Excavation
Dirt removal, trenching, small excavation, rough grading, and site support work.
Site Prep
Clearing, demolition, grading, hauling, and equipment work to prep your property.
Frequently asked questions
How much does a French drain cost in Northern California?
French drain installation — trench, drain rock, perforated pipe, filter fabric, and backfill — runs $25–$60 per linear foot in Northern California. A 100-foot rear yard French drain would typically cost $2,500–$6,000. Longer runs, deeper trenches, tight access, rock encountered, or difficult discharge routing push costs higher. The trench cut is the most labor-intensive part; flat, accessible ground runs closer to the low end.
Will a French drain solve my ponding problem?
It depends on what's causing the ponding. French drains are effective for subsurface water and soil saturation — water that seeps up or accumulates below grade. If the ponding is caused by surface sheet flow running toward a low point, a surface swale or regrading may be more effective. Most chronic ponding problems involve both surface and subsurface water, and the best solution addresses both.
Do I need a permit for drainage grading in California?
Most residential drainage grading and French drain installation doesn't require a permit. Exceptions: projects disturbing 1 or more acres must obtain coverage under the SWRCB Construction General Permit and prepare a SWPPP. Some counties require grading permits for cuts or fills exceeding a threshold volume. If drainage work connects to a public storm drain or alters drainage patterns across property lines, additional approvals may be required.
How do I know if my yard slope is causing foundation problems?
Negative slope — ground that falls toward the foundation rather than away from it — is the most common drainage problem around residential foundations. You can check with a 4-foot level: California building code recommends a minimum 2% slope (about 1 inch per 4 feet) away from the foundation for the first 6–10 feet. If water is collecting against your foundation during rain, or if you have persistent crawl space moisture, regrading and possibly a French drain near the foundation are worth investigating.
What is daylighting a drain?
Daylighting means running a drain pipe to a point where it discharges visibly to the surface — typically at a slope face, property edge, or swale. It's the most reliable discharge method because there's no downstream pipe or connection to fail. A daylighted drain flows by gravity and can be visually inspected. The discharge point needs to be located where the outflow won't erode the slope or create a neighbor drainage problem.