Do you have potholes, ruts, or soft spots in your driveway?
Each year I visit many potential customers and discuss the condition of their driveway. I am often asked the same questions so I thought I’d discuss them here. While not all conditions are identical, there are common issues in gravel driveways that lead to problems. To function properly a gravel driveway needs several items:
- A solid base of gravel. If a driveway doesn’t have the proper base of gravel it will not hold up to repeated traffic.
- A surface that is “crowned”.
- Shoulders or sides/edges that are lower than the driveway.
- Ditches or swales on each side of the driveway, although there are times when a ditch is not feasible on both sides.
- Culverts that drain the ditches if needed.
If a driveway doesn’t have a proper base of gravel it will be soft, allowing a car to sink into the gravel, creating ruts. All gravel driveways to a certain extent will get muddy and soft at the surface, however, deep ruts are an indicator that the base gravel isn’t supporting the vehicle traffic. Water migrating into the base gravel can also create an unstable driveway. This often happens when a driveway is surrounded by wetlands, or doesn’t have adequate ditches or swales to guide the water away from the driveway.
If a driveway isn’t crowned, or the shoulders are high, it causes a couple of issues. The most obvious is that water will run down the driveway, not off the driveway as shown in the picture at left.
When water runs down the driveway it will most often do so in the tire tracks causing erosion and washouts. If the water doesn’t run but is left to stand on, rather than run off, the driveway it will soften the gravel and create potholes. Potholes will continue to grow in size, as each time a car passes over them more gravel is washed out.
The shoulders or sides/edges of the driveway also need to be lower than the travel lane, even if it’s crowned properly. If the shoulders are too high the water will run only to the edge of the driveway and not over it into the ditch or swale. This condition, much like a lack of crown will begin to erode the outer edges of a driveway, eating into the travel lane.
Ditches and swales are an equally important part of a driveway. Even if the driveway is properly crowned and the shouders are cut down, water needs to be able to run away from the driveway sides. If water is left to stand on the roadsides it can migrate into the base gravel causing it to become soft. Working in conjunction with the ditches are culverts. Culverts typically allow for cross-road drainage on a driveway without other entrances. They are also used when there are entrances or exits on the driveway, although these are set parallel to the road.
Repairing the driveway:
Gravel portion of the driveway-
Depending upon the amount and quality of the surface gravel on a driveway it can often be scarified and raked back into shape. It’s crucial, however, to scarify the existing gravel surface below the level of any potholes and damage. Simply filling potholes doesn’t not adequately fix the problem. Once the gravel has been scarified it can then be raked into a crown and compacted. If the surface gravel has been washed away or is very thin, gravel may need to be brought in to resurface the driveway. This is done after the initial scarification and raking.
The shoulders/edges of the driveway may need to be cut down. This may be done in conjunction with the raking or done separately with the excavator. In many cases the material on the shoulders isn’t gravel and therefore usually needs to be hauled away.
Often the drainage ditches and swales need to be cleaned out or cut down depending upon condition or whether they were actually created when the driveway was built. This is done with the excavator and a “clean-up” or grading bucket. The shoulder and ditch work are usually done together, as the debris and material in the ditch needs to be hauled away too.
Culverts are the way in which water crosses under the driveway, or sometimes parallel to it, depending upon how the driveway is laid out. If the culvert is an old steel version they can rust and completely deteriorate, which will require replacement. At other times culverts can completely fill with gravel and sediment if the outflow end is blocked. In this situation the culvert is either replaced or removed and cleaned out then reset. Shallow culverts can be lifted by frost and will require resetting if possible. Unless the state or code requires it most culverts installed today are polyethylene smooth wall culverts. The outside of the culvert is ribbed for compression strength, however, the inside of the culvert is smooth allowing water to run freely.
An ounce of prevention:
Gravel driveways require maintenance. There is no way around it. Maine seasons are tough on gravel, and that has been especially true as of late. Plowing, freeze/thaw cycles, rain, and wind all take their toll on a driveway. One way to keep the driveway in shape is to rake it at least on an annual basis, usually in the spring/early summer. Doing so repairs the damage caused by the winter plowing and mud season and sets the driveway up for the summer traffic. Once the driveway is raked it is then compacted with a vibratory roller to help keep the gravel in place.
I’m often asked if there is an alternative to gravel that will require less maintenance. In many applications an often-used alternative is reclaimed asphalt, or reclaim as it’s known. Reclaim is old asphalt that has been ground up and closely resembles gravel in its form, meaning that it’s worked in much the same way. It is applied the same way to the surface of a driveway and can be raked and maintained using the same methods. The difference is that reclaim has very little gravel “fines” in it so that it doesn’t wash away as easily or get as muddy, depending upon the application. For the same reason it doesn’t get as dusty when it’s very dry. It’s often used in areas where erosion is a problem and when a homeowner doesn’t want to deal with the surface mud of a gravel driveway. It’s important to note, however, that reclaim isn’t “hot top”. It doesn’t bond together in a uniform covering for your driveway, nor does it “fix” underlying structural problems. It’s used to surface a driveway only, so the same gravel driveway is underneath a reclaim surface.