Stormwater Management Manual 4-25 Eugene 2014 <br />4.5.10 Swale O & M Plan Swales are filtration stormwater conveyance facilities that provide flow control and stormwater quality benefits. Swales are long and narrow vegetated and grassed depressions used to collect and convey stormwater runoff which allows pollutants to settle and filter out as the water flows through the facility. All facility components, vegetation, and source controls shall be inspected for proper operations and structural stability, 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. <br />Training and/or Written Guidance information for operating and maintaining Swales 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. <br />Inspection Logs shall be kept by the facility owner demonstrating the following items have been inspected and are being maintained properly: <br />• Access to Swales shall be safe and efficient. Obstacles preventing maintenance personnel and/or equipment access to the components of the facility shall be removed. <br />• Channelization and causes for altered water flow shall be identified and corrected upon discovery. Stormwater should exit the vegetative filter as sheet flow, unless a collection drainpipe is used. <br />• 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. <br />• Erosion Damage shall be identified and controlled when native soil is exposed or erosion channels are forming. <br />• Grassed Swales shall be mowed to 4”-9” high and grass clippings shall be removed no less than 2 times per year. <br />• Infiltrating Swales shall be excavated and cleaned, and gravel or soil shall be replaced to correct low infiltration rates. The Swale should drain within 48 hours of a storm event. <br />• Inlets shall maintain a calm flow of water entering the Swale and shall be cleared when conveyance capacity is plugged to ensure unrestricted stormwater flow to the rain garden. <br />• Mulch shall be replenished as needed to ensure healthy plant growth. <br />• Nuisance and Prohibited Vegetation from the Eugene Plant List (such as blackberries and English Ivy) shall be removed when discovered. Invasive vegetation contributing up to 25% of vegetation of all species shall be removed and replaced. <br />• Outlets shall be cleared when 50% of the conveyance capacity is plugged.