Agenda - 06-21-2022; 8-l - Orange County Southern Campus Expansion Stormwater Operations and Maintenance Plan Agreement with Town of Chapel Hill (2501 Homestead Road, Chapel Hill)

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10 Table 1: Inspection and Maintenance Provisions for Bioretention Cell INSPECTIONSFREQUENCY OF MAINTENANCE ACTIVITIES • Watering is needed twice a week until the plants become established (commonly Upon 6-8 weeks) and then as needed during first growing season (April-October), construction depending on rainfall. completion • Remove and replace dead plants. • Remove any tree stakes or wires six months after planting. • Mow any bioretention with turf cover to a height of approximately six to eight inches and remove grass clippings. • Check inlet, collection system and outlet device for clogging. Remove Once every accumulated grit, leaves, debris and any other obstructions and dispose off-site. quarter • Inspect for ponding and bare or eroding areas and make adjustments as necessary. • Remove trash and/or debris from the bioretention area. Twice during the growing • Pull out weeds and dead, diseased, or invasives plants preferably by hand. season • For bioretention areas without turf cover, supplement triple shredded hard wood mulch in devoid areas to maintain a maximum 3 inch layer. • Prune trees and shrubs to best professional practice. Thin vegetation so that Annually sunlight can penetrate the bioretention surface. • Inspect the observation/cleanout wells to ensure that the underdrain is functioning. If clogging has occurred, wash out the underdrain. • Inspect all structural elements. • Conduct a soil test for pH and heavy metals and determine the infiltration rate. • For bioretention areas without turf cover, remove and replace the mulch layer with triple shredded hard wood. The ideal time to reapply mulch is in the late Once every spring. 2-3 years •An extensive replanting is required if 50% minimum coverage throughout the basin is not achieved in the bioretention after the second growing season. Once every 5 • Perform facility"make-over'to maintain intended landscaping regime and to 7 years address any maintenance problems detected during routine inspections. After 5 growing seasons,the vegetation should achieve 75/o coverage. Vegetation • If the bioretention cell suffers from dead or diseased plants or overgrown with As Needed (Typical invasive species, evaluate the source of the problem: soils, hydrology, species, Problems) and/or type of disease to determine the cause of the plant failure. o Remediate the problem by selecting new species and/or implementing an eradication plan for invasives. BIORETENTION PAGE 2 OF • • •