Building or fixing a gravel driveway with a mini excavator and dump trailer

Driveway jobs this pair handles

The Kubota U27-4 digs, cuts and spreads with its bucket and backfill blade. The 7x14 dump trailer hauls sod and soft soil out and brings rock back in. Together they cover driveway jobs like these:

• New gravel driveway: Strip the sod, shape the subgrade, then build it up in layers of base rock and top rock.
• Regrade a rutted or sunken driveway: Cut the high spots, fill the low ones, and bring back a crown so water runs off.
• Potholes and washboard: Cut out and reshape the damaged area instead of tossing loose gravel in the holes.
• Ditch and culvert at the road: Clean out the ditch and reset a plugged or crushed culvert, after the permit.
• Widen it or add a turnout: A wider parking spot or turnaround uses the same steps on a smaller patch.

Just topping up worn gravel? The gravel hauling guide covers trips and tarping. Leveling a shed pad or patio base instead? See the grading guide.

Permits before you dig

Unincorporated Pierce County

• Repair or re-gravel: the county’s driveway FAQ says you generally do not need a permit if you are not changing the grade, drainage or width. A driveway in a critical area may need one, and the county asks you to contact Development Engineering before you start.
• The approach at the road: Pierce County Code 17B.10.101 requires a driveway approach permit to build, repair, alter or use an approach to a public road. An older driveway that was never permitted, or one that will carry more traffic, may have to be brought up to current standards.
• Surfacing and culvert: the FAQ says the permit checks sight distance, width, grade and surfacing (asphalt or concrete). The county’s standard drawing PC.F1.1 (PDF) for a residential approach over an open ditch shows a paved approach with a concrete culvert of at least 12 inches, and says driveway runoff may not drain onto the road unless the design accounts for it. Check with the county for the current standard before you buy pipe.
• New gravel area: the site development FAQ lists driveway construction and creating impervious surfaces among permit triggers, and it names gravel driveways among the most common impervious surfaces. The Fill and Grade page sets a grading permit at more than one cubic yard in critical areas or more than 50 cubic yards elsewhere.

Inside a city

• Puyallup: a driveway approach is work in the public right-of-way and needs a city Right of Way permit (PDF).
• Bonney Lake: a new driveway onto a public street needs a road approach permit (Civil & Utility Permits). The city also says 500 sq ft or more of new or replaced hard surface generally triggers stormwater review.
• Sumner: work on a driveway approach needs a Sidewalk/Driveway Replacement permit with a right-of-way bond (Sidewalks).
• Auburn: using the street for your project needs a Right-of-Way Use Permit; for a new approach, check with the city (application, PDF).
• Enumclaw: the city’s land disturbance form counts crushed surfacing as hard surface toward its 2,000 sq ft threshold, and building in city right-of-way needs a Right of Way permit (PDF).

The county and the cities do not word these rules the same way, so check with the city or county for your parcel. Area pages: Puyallup · Bonney Lake · Sumner · Auburn · Enumclaw.

Call WA 811 at least two, but no more than ten, business days before you dig. Cutting a ditch or trenching for a culvert can hit a buried line, and private lines are not marked.

Build it in layers

These steps follow the FHWA Gravel Roads Construction and Maintenance Guide (PDF). It was written for public gravel roads, so treat it as a starting point for a driveway.

1. Strip the sod and topsoil. The guide says topsoil contains organic matter that is never good for a road surface. Dig it off with the bucket and pile it for the garden, or haul it out in the trailer. Pierce County’s Dirt page lists places that take clean fill dirt (no sod or debris).
2. Fix soft spots in the subgrade. Where the ground stays wet and pumps, the guide says either dig out the weak soil or lay a geotextile fabric as a separator so fines can’t work up into the rock. Leave the subgrade smooth and free of rocks, roots and stumps.
3. Lay the fabric right. Keep it free of wrinkles and pinned down, overlap the edges at least 18 inches, and never drive on bare fabric. Back-dump the rock onto what you have already spread and push it out with the blade. The guide says the first layer on fabric is generally at least 6 inches.
4. Shape a crown. The guide recommends a straight crown rising about 1/2 inch per foot from the edge to the center, about 4 percent, and says not to exceed 6 percent. A rounded crown leaves the middle flat, and that is where potholes start. On a driveway that slopes to one side, the same slope can run edge to edge.
5. Base rock, then top rock. The guide says base gravel has larger stone and few fines so it drains, while surface gravel needs a blend of stone, sand and fines that bind into a crust. Base rock used on top stays loose. Ask your supplier for each layer by name and for their thickness advice.
6. Compact as you go. The guide says that, if possible, a roller greatly improves the finished surface and leaves it denser and stronger. Plan how you will compact each layer before the rock arrives.

Kubota lists the U27-4’s overall width and its blade width as 4 ft 11 in, and says its auto-shift down gives smoother operation when dozing and turning (Kubota U27-4 brochure, PDF). Walk the route in from the street before you book.

Ditch and culvert at the road

• The FHWA guide says small culverts plug easily with eroded soil and debris, and that a plugged or collapsed culvert can send water over the road. Clean the ditch and both ends of the pipe.
• It also shows a new culvert set right on the flow line of the ditch, so water does not pond at either end.
• The ditch and culvert at a county road usually sit in the right-of-way, so get approval from the county or city before you dig there.
• Keep driveway runoff off the road. Shape the crown and edges so water drops into the ditch or onto your own ground.

Fixing potholes and washboard

• Potholes: the FHWA guide says it is generally not wise to just fill problem areas with new gravel. Cut the potholes out, reshape the surface back to its crown, then add rock in an even layer.
• Washboard: the guide lists four causes: hard braking and acceleration, lack of moisture, poor gravel and lack of crown. Rework it while the gravel is moist, cutting 1 inch or more below the bottom of the ripples, then mix, relay and compact.
• Before adding new rock: lightly scarify even a hard, smooth surface so the new layer bonds to the old one.
• Where gravel meets pavement: the guide says these transitions pothole easily, and to avoid pushing gravel onto the paved surface.

Day, weekend or week?

Mini excavator: At the day rate, 3 days is $1,005 and 4 days is $1,340, vs $1,050 for a week. The weekend rate is $490 (Friday 9 AM pickup to Monday 3 PM return).

7x14 dump trailer: At the day rate, 3 days is $465 and 4 days is $620, vs $575 for a week. The weekend rate is $200 (Friday 9 AM pickup to Monday 3 PM return).

A pothole fix may fit in a day. A new driveway with stripping, fabric and several rock loads usually goes better over a weekend or a week.

Prices are before WA sales tax and the 1.25% heavy equipment rental tax where it applies. Your exact total shows at checkout.