Water flowing under box culverts can be a significant problem. It can quickly cause some of the following problems:
- settlement of the box culvert
- erosion, and settlement of, the adjacent embankment or ground
- catastrophic failure of the structure
CJGeo specializes in repairing water flowing under box culverts using geotechnical polyurethane grouting.
Causes
One of the most common causes of water flowing under box culverts is poor control of the subgrade during installation. Poorly controlled materials are highly prone to erosion, and settlement. As soils consolidate, voids can form under the structure, and water typically easily finds a way to these voids, and starts flowing through them. This is referred to as piping, where water is flowing outside, and along, a drainage structure such as a box culvert.
Consequences
The consequences of water flowing where it shouldn’t be can be pretty severe. Significant embankment settlement is one of the most common signs of water piping outside of a box culvert.
It’s not uncommon to see box culverts where all dry weather flow is below or around the structure. If a structure isn’t pile supported, this can cause significant settlement of the structure itself, sometimes to the point of requiring replacement. Addressing piping before it causes a complete failure of a structure is a very wise investment.
Repair Methods
Addressing water flow around and under box culverts is pretty straightforward. There are a few considerations that play into selecting the most appropriate method:
- velocity & volume of the water flow
- live & dead loads from cover, traffic, etc
- environmental risks
Velocity & volume of water flow around the structure are important to quantify. Some chemical grouts used for low velocity water control will easily washout in high volume or high velocity water. High velocity water flow can also wash out cementitious grouts, which can cause significant increases in pH downstream and harm aquatic life.
It’s important to evaluate the total loads that the grout must bear. High expansion chemical grouts injected into water tend to be very elastomeric (squishy), and generally don’t provide adequate bearing. Flowable fill has high strengths, but typically significantly higher than what the actual loads are. This is generally just a result of mix designs than being a sign of a true high strength requirement.
Geotechnical polyurethanes, such as CJGrout 35NHV61, are ideally suited for stopping high volume leaks, filling voids, and providing adequate bearing capacity. CJGrout 35NHV61 is designed to be injected directly into high velocity water flows without washing out, provides a roughly 11ksf unconfined compressive strength, and is certified for potable water contact. CJGeo routinely performs pre, concurrent and post grout water testing to confirm that CJGrout geotechnical polyurethanes do not leach MDI or other chemicals into water. CJGrout geotechnical polyurethane grouts do not contain PFAS.
Speak With An Expert
Facing a challenge with water flowing under box culverts? Give us a shout or shoot us a text. Click the state marker for the location of the project for contact info for the appropriate rep.
