A retail store specializing in the sale of gardening items, located in La Prairie on the South Shore, requested the intervention of our experts after discovering groundhogs actively settling under the concrete slab of its rear parking lot. Several galleries had been dug along the foundation of the building, weakening the structure at the level of the load-bearing wall. Employees had also seen burrows on the edge of the wooded lot adjacent to the business. The problem threatened not only the integrity of the building, but also the safety of customers in the parking lot, where the first ground subsidence had already been observed near a particularly deep burrow.
Assessing the extent of the infestation
During the initial inspection carried out in the morning, our technicians located five active burrows: three along the foundation of the business and two along the fence delimiting the wooded lot located on the Saint-Constant side. The presence of freshly disturbed soil, scratch marks and characteristic droppings confirmed that they were groundhogs (Marmota monax), a species abundant in the transition zones between built spaces and natural environments on the South Shore. The partial structural inspection revealed that the digging had already caused the beginning of subsidence under a section of the concrete slab of the parking lot. A perimeter security zone was immediately demarcated around this area to protect customers.
The inspection also verified that the marmots had not accessed the interior of the building through the gallery along the foundation. The maintenance openings on the north façade, normally open during deliveries, have been identified as points of vulnerability to be monitored.
Multipoint capture strategy
Given the number of burrows, our team deployed several cage traps simultaneously, positioned directly in front of the entrances to the most active galleries. Bait composed of fresh apple slices, carrots and alfalfa were used, these plants being particularly attractive to the marmot in the summer season. The traps were checked every morning when the business opened, before the arrival of customers, for five consecutive days. A total of four marmots were captured and relocated to a remote wooded area beyond Highway 132 at a distance that would ensure they would not return to the site. Our specialized animal capture service is equipped to handle multi-point situations like this, with multiple traps deployed simultaneously. Our exterminator in La Prairie is familiar with the habits of the local wildlife and the appropriate relocation areas in the area.
Blocking burrows and strengthening the foundation
Once the captures were confirmed by a final inspection of the burrows, our technicians proceeded to permanently block each gallery. The method used combines progressive filling with compacted gravel in successive layers, followed by concrete pouring on the surface to freeze the fill. An L-shaped wire mesh was then buried thirty centimeters deep around the entire perimeter of the exposed foundation, forming a continuous underground barrier. This system prevents any new digging at the junction between the ground and the building, which is the preferred area for groundhogs to initiate their galleries. The closure of potential entry points has been extended to the bottom of the fence panels to cut off the natural corridor between the wooded lot and the parking lot.
Long-term follow-up and preventive measures
The owner of the business has received specific recommendations to reduce the attractiveness of the site to marmots in the long term: removal of piles of rock and stacked wood that serve as shelter, regular maintenance of the vegetation at the edge of the foundation, and visual inspection of potential burrows each spring before the marmots are put into activity. It is also recommended to monitor the condition of the buried mesh after thawing, as freeze-thaw cycles can sometimes move materials slightly. A control visit was carried out four weeks after the intervention to confirm the absence of new active burrows and to check the integrity of the work. Nova Extermination offers annual maintenance contracts for businesses wishing to proactively monitor invasive wildlife problems. Check out our other commercial capture projects to see how we adapt our approach to different retail contexts on the South Shore.