Leesburg-backed bill would require mapping of trees' critical root zones during development

Delegate Martinez, patron of House Bill 2238, told the workgroup the measure responds to a local request from the town of Leesburg to protect mature trees during development by requiring critical root zone (CRZ) identification in the development process. "Mature trees provide immediate benefits, resilient to drought, strong root systems, decades of shade and stormwater management capacity, and new planting simply can't replace [them] for many years," Martinez said.

Melissa Westbrook, urban forester for the town of Leesburg, said the bill would empower localities to request developers map or otherwise document critical root zones so local planners can account for roots that cross property lines. She described an industry standard used by arborists: a CRZ radius typically calculated by multiplying a tree's diameter at breast height (DBH) by 1 to 1.5 feet per inch of DBH. "The critical root zone is typically larger than a drip line, particularly for mature ... trees," Westbrook said, and localities need that information to avoid root damage that can kill trees after construction even when the trunk is left standing.

Home-building representatives raised concerns about cost, subjectivity and unintended incentives. Andrew Clark of the Home Builders Association of Virginia said the draft could require a fairly extensive study and cited builder estimates that a CRZ study for a modest parcel could add roughly $7,000 to $15,000 in preconstruction costs depending on site conditions. Clark warned that higher permitting costs and delay risk might create an incentive for some developers to remove trees rather than preserve them. He also noted potential legal and practical complications when CRZs extend onto adjacent private property.

Town staff described existing tools and standards. Westbrook said Leesburg's design and construction manual currently requires tree-protection fencing, site-plan depiction of preserved trees and condition assessments; the proposed code change seeks to codify the use of CRZ measurement and to address root impacts coming from trees on neighboring properties.

Members suggested next steps that would limit unintended consequences: adopt an industry standard CRZ definition in the statute (for example, 1.5 feet per inch DBH), clarify authority and process for trees on adjacent properties, and identify whether the statute should set a statewide standard or allow locality discretion. No formal action was taken; legislators and stakeholders agreed to continue refining language.