HomeMy WebLinkAboutNotes Applicant 12/9/2024 (8) Stormwater Management Manual 4-23 Eugene 2014
4.5.9 Stormwater Planter O & M Plan
Stormwater Planters are infiltration and filtration stormwater facilities that can provide flood control, flow control and stormwater quality benefits. Stormwater Planters are walled vegetated surface reservoirs used to collect and treat stormwater runoff from impervious surfaces by allowing pollutants to settle and filter out as the water percolates through the vegetation and soil mediums before infiltrating into the ground below or being piped to its downstream destination. Stormwater Planters can be used to help fulfill a site’s required landscaping area requirement and should be integrated into the overall site design. Numerous design variations of shape and planting scheme can be used to fit the character. All facility components and vegetation shall be inspected for proper operations and structural stability. These inspections shall occur, at a minimum, quarterly for the first 2 years from the date of installation, 2 times per year thereafter, and within 48 hours after each major storm event.
Training and/or Written Guidance information for operating and maintaining Stormwater Planters shall be provided to all property owners and tenants. A copy of the O & M Plan shall be provided to all property owners and tenants.
Inspection Logs shall be kept by the facility owner demonstrating the following items have been inspected and are being maintained properly:
• Access to Stormwater Planters shall be safe and efficient. Obstacles preventing maintenance personnel and/or equipment access to the components of the facility shall be removed.
• Debris and Litter shall be removed to prevent channelization, clogging, and interference with plant growth. Fallen leaves and debris from deciduous plant foliage shall be raked and removed.
• Erosion Damage shall be identified and controlled when native soil is exposed or erosion channels are forming.
• Filter Media consisting of sand and/or topsoil shall be tested to ensure stormwater percolates through the planter. Remove and replace sand and/or topsoil to correct percolation deficiencies.
• Infiltrating Stormwater Planters shall be excavated and cleaned, and gravel or soil shall be replaced to correct low infiltration rates. Water should drain through the planter within 3-4 hours after a storm event.
• Inlets shall be cleared when conveyance capacity is plugged to ensure unrestricted stormwater flow to the rain garden.
• Mulch shall be replenished as needed to ensure healthy plant growth.
• Nuisance and Prohibited Vegetation from the Eugene Plant List (such as blackberries and English Ivy) shall be removed when discovered. Invasive
Stormwater Management Manual 4-24 Eugene 2014
vegetation contributing up to 25% of vegetation of all species shall be removed and replaced.
• Outlets shall be cleared when 50% of the conveyance capacity is plugged.
• Piping shall be cleared of sediment and debris to maintain conveyance capacity.
• Planter Walls shall be examined for deficiencies, such as rot, cracks, and failure, and repaired as needed. Holes that are not consistent with the design and allow water to flow directly through the planter to the ground shall be plugged.
• Sedimentation build-up near or exceeding 2” in depth shall be hand-removed with minimum damage to vegetation using proper erosion control measures. Sediment shall be removed if it is more than 4 inches thick or so thick as to damage or kill vegetation.
• Vegetation shall be healthy and dense enough to provide filtering while protecting underlying soils from erosion. Dead vegetation shall be removed to maintain less than 10% of area coverage or when vegetative filter function is impaired. Vegetation shall be replaced immediately to control erosion where soils are exposed and within 3 months to maintain cover density.
Spill Prevention Measures shall be exercised on site when handling substances that contaminate stormwater. Releases of pollutants shall be corrected as soon as identified.
Non-Chemical Pest Control measures shall be taken to prevent development of insects, mosquitoes, and rodents.