Maxville Vineyard Conversion Agricultural Erosion Control Plan (ECP) - P23-00130

The Maxville Vineyard Conversion project, identified by Agricultural Erosion Control Plan (ECP) #P23-00130-ECP, involves the environmental review and development of approximately 56.2 gross acres for vineyard conversion in St. Helena, California. Managed by the Napa County Department of Planning, Building and Environmental Services, the project entails clearing vegetation, earthmoving, and the installation and maintenance of erosion control measures across ten vineyard blocks. The development area consists of 42 net planted acres situated on land with slopes ranging from 5% to 37%, averaging 20%. The project site is located within the Napa River and Sacramento River watersheds across three parcels totaling approximately 1,025 acres. To mitigate environmental impacts, the plan includes the preservation of 32.4 acres of canopy and adheres to existing conservation easements overseen by the Napa County Land Trust. The project is subject to rigorous environmental and operational constraints to protect biological resources, water quality, and air quality. Key mitigation measures include strict protocols for bat habitat protection, requiring qualified biologists to supervise tree removal during specific seasonal windows, and the use of EPA Tier 4 Final emission standards for heavy construction equipment. Due to the site's location within a municipal watershed, earth-disturbing activities are prohibited between September 1 and April 1, with exceptions only for winterization measures. The construction schedule is divided into a pre-planting stage beginning April 1, 2025, and a planting stage in 2026, with an estimated total construction duration of 500 days. Technical assessments, including soil loss analysis, geologic stability reports, and hydrology studies, have been conducted to ensure that the development will not result in a net increase in erosion or significant changes to watershed runoff.