1001 N BROADWAY LEARNING RESOURCE CENTER 2026-01-15

Recommended Frequency a Table V-A.21: Maintenance Standards - Bioretention Facilities (continued) Maintenance Com- Condition when Maintenance is Needed (Stand- ponent Inspection Routine Main- ards) Action Needed (Procedures) tenance Pre-moisten soil to break surface tension of dry or hydrophobic soils/mulch, followed by several more passes. With this method, each pass increases soil absorption and allows more water to infiltrate priorto runoff • Add a tree bag or slow-release watering device(e.g., bucket with a perforated bottom)for watering newly installed trees when irrigation system is not present • 10 to 15 gallons per tree • 3 to 5 gallons per shrub Summer watering Once every 2-4 • 2 gallons water per square foot for groundcover areas (second and third weeks oras needed Trees, shrubs and groundcovers in second or third • Water deeply, but infrequently, so that the top 6 to 12 inches of the root zone is moist years) during prolonged year of establishment period dry periods • Use soaker hoses or spot waterwith a showertype wand when irrigation system is not present Pulse water to enhance soil absorption, when feasible o Pre-moisten soil to break surface tension of dry or hydrophobic soils/mulch,followed by several more passes. With this method, each pass increases soil absorption and allows more water to infiltrate prior to runoff • Plants are typically selected to be drought tolerant and not require regular watering after establishment; however, — Summer watering trees may take up to 5 years of watering to become fully established (after establishment) As needed Established vegetation(after 3 years) • Identify trigger mechanisms for drought-stress (e.g., leaf wilt, leaf senescence, etc.)of different species and water immediately after initial signs of stress appear • Water during drought conditions or more often if necessary to maintain plant cover Pest Control • Identify the cause of the standing water and take appropriate actions to address the problem (see"Ponded water") • To facilitate maintenance, manually remove standing water and direct to the storm drainage system (if runoff is from Mosquitoes B, S Standing water remains for more than 3 day s after the non pollution-generating surfaces)or sanitary sewer system(if runoff is from pollution-generating surfaces)after get- end of a storm ting approval from sanitary sewer authority. • Use of pesticides or Bacillus thuringiensis israelensis(Bti)may be considered only as a temporary measure while addressing the standing water cause. If overflow to a surface water will occur within 2 weeks after pesticide use, apply for coverage under the Aquatic Mosquito Control N PDES General Permit. • Reduce site conditions that attract nuisance species where possible(e.g., plant shrubs and tall grasses to reduce open areas for geese, etc.) • Place predator decoys Nuisance animals As needed Nuisance animals causing erosion, damaging plants, or depositing large volumes of feces • Follow IPM protocols for specific nuisance animal issues (see"Additional Maintenance Resources"section for more information on IPM protocols) • Remove pet waste regularly • For public and right-of-way sites consider adding garbage cans with dog bags for picking up pet waste. Insect pests Every site visit Signs of pests, such as wilting leaves, chewed • Reduce hiding places for pests by removing diseased and dead plants associated with leaves and bark, spotting or other indicators 0 For infestations, follow IPM protocols (see"Additional Maintenance Resources"section for more information on IPM 2019 Stormwater Management Manual for Western Washington Volume V-Appendix -Page 1024