Groundhogs, also known as woodchucks, are common North American rodents whose extensive burrow systems often cause property damage. These tunnels can stretch up to 50 feet long and reach depths of five feet, weakening soil stability and posing a tripping hazard. Safely and effectively filling a groundhog hole requires ensuring the animal is gone, stabilizing the compromised soil, and implementing measures to prevent the rodent’s return.
Assessing the Burrow for Activity
Before attempting to fill any hole, confirm that the groundhog or any other animal is not currently inside the burrow. Filling an occupied tunnel is inhumane and will prompt the trapped animal to dig a new exit, potentially causing more damage nearby. Remediation is generally best attempted during late summer or early fall when young groundhogs have dispersed and adults are not yet hibernating.
A simple, non-invasive method to check for occupancy is the “paper test,” where you loosely crumple newspaper, leaves, or light soil into the entrance. If the material remains undisturbed after 24 to 48 hours, the burrow is likely vacant. Signs of recent activity include fresh mounds of excavated soil, clear paw tracks, or a disturbed plug.
It is important to locate and check all potential openings, as a groundhog burrow network typically includes one main entrance and several smaller escape holes. If the burrow appears active, humane trapping and relocation or consulting a professional wildlife control service may be necessary before proceeding. Groundhogs are most active outside the burrow during the early morning and late afternoon.
The Step-by-Step Filling Process
Once the burrow is confirmed empty, the filling process must focus on deep compaction to prevent future sinkholes and deter re-excavation. Begin by gathering materials such as coarse gravel, crushed stone, and native topsoil. Coarse material is recommended for the initial fill layer because its irregular shapes interlock, providing better long-term stability and drainage than loose soil alone.
Start by shoveling the coarse material deep into the tunnel system, aiming to fill the main chambers and shafts. Substantial material may be required for large, complex burrows. After adding the initial layer, use a tamper or heavy object to compact the material firmly, pushing it against the tunnel walls.
The next step involves “washing” the fill material by slowly adding water to the hole, which helps settle the coarse materials into any remaining voids. Repeat this process, alternating between adding more gravel or stone and compacting it, until the material is a few inches below the ground surface. For holes near foundations or high-traffic areas, a concrete or grout slurry can be used for the final deep fill, creating a permanent, impenetrable barrier.
The final stage is restoring the surface area using native topsoil. Fill the remaining space with soil, tamp it down firmly, and then cover the patch with grass seed or sod. This blends the repair with the yard and provides a vegetative layer that helps prevent surface erosion.
Deterring Future Excavation
After successfully filling a burrow, preventing the groundhog from digging a new hole nearby is the next consideration. Habitat modification is an effective first step, focusing on removing potential cover near the repaired area. Groundhogs prefer to dig where they feel secure, so removing debris, brush piles, or stacked wood eliminates their immediate shelter.
For long-term protection, especially around vulnerable structures like sheds or foundations, physical barriers are the most reliable deterrent. An L-shaped wire mesh barrier, constructed from heavy-gauge hardware cloth, is highly effective. This involves burying the mesh vertically at least 12 inches deep and then bending the bottom 6 to 12 inches outward in an “L” shape away from the structure.
The L-shape design prevents the groundhog from digging straight down past the barrier, as they encounter the horizontal section of mesh. Topical deterrents, such as applying predator urine or a castor oil solution, can also discourage investigation by signaling a danger presence. These deterrents can serve as a temporary measure while the animal seeks a less threatening location.