Impacts of tree root intrusion on stormwater and sewer systems: balancing urban greenery with infrastructure in an Australian case study

Street trees provide valuable ecological and social benefits to urban environments; however, their root systems can compromise nearby infrastructure, reducing structural integrity and service life. This investigation quantifies the extent of these impacts, underscoring the significant asset damage and financial challenges posed by tree root intrusion into stormwater and sewer systems. Data collected from Orange City Council suggests that tree roots affect approximately 23.8% of stormwater lines, 20% of sewer reticulation mains, and 26.1% of sewer trunk mains, with Asbestos Cement (AC) pipes found to be the most negatively impacted. Financial modelling indicates that the current Council budget for asset renewal and replacement is severely underfunded, with stormwater and sewer allocations falling short by factors of 5.6 to 11.2 and 2.4 to 4.8, respectively, depending on damage severity. The study ranks commonly planted urban tree species based on their potential to damage infrastructure. The findings demonstrate the need for targeted preventive measures, such as the strategic selection of less invasive species, to mitigate infrastructure damage, reduce long-term costs and increase asset lifecycle. This study also outlines several potential solutions such as tree removal, root barrier installation, appropriate species selection, chemical treatments, and inspection programs evaluated in terms of cost, environmental impact, and feasibility based on existing literature. By integrating these strategies, local governments can better balance urban greenery with essential infrastructure durability, ensuring that the ecological benefits of urban forestry do not come at an unsustainable economic cost.