Bioswale Bioswale Clairemont Boys and Girls Club Clairemont Boys and Girls Club
Background Background Bioswales are shallow, open channels Bioswales are shallow, open channels with gently sloping sides that can be with gently sloping sides that can be incorporated into landscapes to direct incorporated into landscapes to direct flow, slow runoff and promote pollutant flow, slow runoff and promote pollutant removal. Vegetation planted within the removal. Vegetation planted within the channel, such as native plants or channel, such as native plants or grasses, helps to slow the flow of grasses, helps to slow the flow of water and filter out pollutants. water and filter out pollutants. Permeable soils encourage infiltration Permeable soils encourage infiltration and are often amended to further and are often amended to further enhance performance and support enhance performance and support plant growth. Bioswales can serve as Site Assessment plant growth. Bioswales can serve as Site Assessment conveyance for storm water in place of conveyance for storm water in place of traditional curbs and gutters; however, Bioswales are versatile landscape design traditional curbs and gutters; however, Bioswales are versatile landscape design the primary objective is infiltration. elements because their paths can meander or the primary objective is infiltration. elements because their paths can meander or follow a straight course. Ideal sites for bioswales follow a straight course. Ideal sites for bioswales include street right-of-ways and along borders include street right-of-ways and along borders Bioswales are effective for removing: or medians of parking lots. Remove curbs or use Bioswales are effective for removing: or medians of parking lots. Remove curbs or use Runoff volume curb cut-outs to funnel runoff into the bioswale. Runoff volume curb cut-outs to funnel runoff into the bioswale. Total Suspended Solids (TSS) Storm drain inlets within the swale should be Total Suspended Solids (TSS) Storm drain inlets within the swale should be Trash raised to encourage ponding and infiltration Trash raised to encourage ponding and infiltration Organics while still capturing overflow. Check dams may Organics while still capturing overflow. Check dams may Bacteria also be needed to control flow. Sizing must ac- Bacteria also be needed to control flow. Sizing must ac- Nutrients count for the drainage volume from the Nutrients count for the drainage volume from the Heavy metals surrounding area. Heavy metals surrounding area. Oil and grease Oil and grease
Drainage Soil infiltration Water table Depth to Facility Drainage Soil infiltration Water table Depth to Facility area rate separation bedrock slope Inflow rate area rate separation bedrock slope Inflow rate > 0.5 in/hr > 10 ft > 10 ft > 0.5 in/hr > 10 ft > 10 ft < 2 acres (if < 0.5 in/hr, (if > 2 but < 10 ft, (if > 2 but < 10 ft, < 2% Mulch: 1 cfs, < 2 acres (if < 0.5 in/hr, (if > 2 but < 10 ft, (if > 2 but < 10 ft, < 2% Mulch: 1 cfs, install UD*) install UD*) install UD*) Grass: 3 cfs install UD*) install UD*) install UD*) Grass: 3 cfs
Sediments: High Nutrients: Medium Runoff volume Groundwater Sediments: High Nutrients: Medium Runoff volume Groundwater Trash: High Metals: High reduction recharge Trash: High Metals: High reduction recharge Bacteria: High Oil and Grease: High Bacteria: High Oil and Grease: High Removal Removal Pollutant Pollutant High no UD*; High no UD*; Pollutant High no UD*; High no UD*; Organics: High Medium with UD* Low with UD* Organics: High Medium with UD* Low with UD* *UD = Underdrain system *UD = Underdrain system
Bioswale Bioswale Clairemont Boys and Girls Club Clairemont Boys and Girls Club
Background Background Bioswales are shallow, open channels Bioswales are shallow, open channels with gently sloping sides that can be with gently sloping sides that can be incorporated into landscapes to direct incorporated into landscapes to direct flow, slow runoff and promote pollutant flow, slow runoff and promote pollutant removal. Vegetation planted within the removal. Vegetation planted within the channel, such as native plants or channel, such as native plants or grasses, helps to slow the flow of grasses, helps to slow the flow of water and filter out pollutants. water and filter out pollutants. Permeable soils encourage infiltration Permeable soils encourage infiltration and are often amended to further and are often amended to further enhance performance and support enhance performance and support plant growth. Bioswales can serve as Site Assessment plant growth. Bioswales can serve as Site Assessment conveyance for storm water in place of conveyance for storm water in place of traditional curbs and gutters; however, Bioswales are versatile landscape design traditional curbs and gutters; however, Bioswales are versatile landscape design the primary objective is infiltration. elements because their paths can meander or the primary objective is infiltration. elements because their paths can meander or follow a straight course. Ideal sites for bioswales follow a straight course. Ideal sites for bioswales include street right-of-ways and along borders include street right-of-ways and along borders Bioswales are effective for removing: or medians of parking lots. Remove curbs or use Bioswales are effective for removing: or medians of parking lots. Remove curbs or use Runoff volume curb cut-outs to funnel runoff into the bioswale. Runoff volume curb cut-outs to funnel runoff into the bioswale. Total Suspended Solids (TSS) Storm drain inlets within the swale should be Total Suspended Solids (TSS) Storm drain inlets within the swale should be Trash raised to encourage ponding and infiltration Trash raised to encourage ponding and infiltration Organics while still capturing overflow. Check dams may Organics while still capturing overflow. Check dams may Bacteria also be needed to control flow. Sizing must ac- Bacteria also be needed to control flow. Sizing must ac- Nutrients count for the drainage volume from the Nutrients count for the drainage volume from the Heavy metals surrounding area. Heavy metals surrounding area. Oil and grease Oil and grease
Drainage Soil infiltration Water table Depth to Facility Drainage Soil infiltration Water table Depth to Facility area rate separation bedrock slope Inflow rate area rate separation bedrock slope Inflow rate > 0.5 in/hr > 10 ft > 10 ft > 0.5 in/hr > 10 ft > 10 ft < 2 acres (if < 0.5 in/hr, (if > 2 but < 10 ft, (if > 2 but < 10 ft, < 2% Mulch: 1 cfs, < 2 acres (if < 0.5 in/hr, (if > 2 but < 10 ft, (if > 2 but < 10 ft, < 2% Mulch: 1 cfs, install UD*) install UD*) install UD*) Grass: 3 cfs install UD*) install UD*) install UD*) Grass: 3 cfs
Sediments: High Nutrients: Medium Runoff volume Groundwater Sediments: High Nutrients: Medium Runoff volume Groundwater Trash: High Metals: High reduction recharge Trash: High Metals: High reduction recharge Bacteria: High Oil and Grease: High Bacteria: High Oil and Grease: High Removal Removal Pollutant Pollutant High no UD*; High no UD*; Pollutant High no UD*; High no UD*; Organics: High Medium with UD* Low with UD* Organics: High Medium with UD* Low with UD* *UD = Underdrain system *UD = Underdrain system Bioswale Bioswale
Ponding Ponding
Flow regulation: Inflow must be non-erosive sheet flow (3 feet per second for grass cells) Flow regulation: Inflow must be non-erosive sheet flow (3 feet per second for grass cells) or use energy dissipating devices. Bioswales can be used effectively in areas with slopes of 2 to or use energy dissipating devices. Bioswales can be used effectively in areas with slopes of 2 to 5 percent by installing check dams to prevent erosive flow velocities; slopes between each check 5 percent by installing check dams to prevent erosive flow velocities; slopes between each check dam should not exceed 2 percent. dam should not exceed 2 percent. Shallow ponding area: Drainage area should be less than 2 acres. Ponded water must Shallow ponding area: Drainage area should be less than 2 acres. Ponded water must completely drain into the soil within 24 hours, with 12 hours preferred as a safety factor. completely drain into the soil within 24 hours, with 12 hours preferred as a safety factor. Ponding depth should be less than 12 inches, 9 inches preferable. Ponding depth should be less than 12 inches, 9 inches preferable. Soil Type: Soil testing should be performed at the site by a licensed soil scientist or geological Soil Type: Soil testing should be performed at the site by a licensed soil scientist or geological engineer to determine the infiltration rate of the in-situ soils. Bioswales should not be used in sites engineer to determine the infiltration rate of the in-situ soils. Bioswales should not be used in sites with highly erodible soils unless turf reinforcement is used. The soil media within the bioswale should with highly erodible soils unless turf reinforcement is used. The soil media within the bioswale should be highly permeable and have an appropriate amount of organic material to support plant growth. be highly permeable and have an appropriate amount of organic material to support plant growth. Vegetation: Bioswales are typically planted with grasses, shrubs, and trees that can withstand Vegetation: Bioswales are typically planted with grasses, shrubs, and trees that can withstand short periods of saturation followed by longer periods of drought. Native plant species or hardy short periods of saturation followed by longer periods of drought. Native plant species or hardy cultivars that are not invasive and do not require chemical inputs are recommended. cultivars that are not invasive and do not require chemical inputs are recommended. Media layers: Media depth must be a minimum of 2 feet. The soil media must comply with the Media layers: Media depth must be a minimum of 2 feet. The soil media must comply with the city’s Storm Water Standards. If existing soils do not meet the criteria, a substitute media must be used. city’s Storm Water Standards. If existing soils do not meet the criteria, a substitute media must be used. Underdrain system: An underdrain must be installed if the current soil drainage is less than Underdrain system: An underdrain must be installed if the current soil drainage is less than 0.5 in/hr. The underdrain pipe should be at least 6 inches in diameter and installed at a 0.5 percent 0.5 in/hr. The underdrain pipe should be at least 6 inches in diameter and installed at a 0.5 percent minimum slope. An underdrain must be installed if the bioswale is within 50 feet of a sensitive, steep minimum slope. An underdrain must be installed if the bioswale is within 50 feet of a sensitive, steep slope. Clean-out pipes must be provided if underdrains are required. slope. Clean-out pipes must be provided if underdrains are required.
To access the complete San Diego Low Impact Development Design Manual, visit: To access the complete San Diego Low Impact Development Design Manual, visit: sandiego.gov/stormwater/pdf/lidmanual.pdf sandiego.gov/stormwater/pdf/lidmanual.pdf To access the Storm Water Design Standards Manual, visit: To access the Storm Water Design Standards Manual, visit: sandiego.gov/development-services/news/pdf/stormwatermanual.pdf sandiego.gov/development-services/news/pdf/stormwatermanual.pdf To report storm water pollution, call (619) 235-1000 To report storm water pollution, call (619) 235-1000 thinkblue.org This information is available in alternative formats upon request. Printed on recycled paper thinkblue.org This information is available in alternative formats upon request. Printed on recycled paper
Bioswale Bioswale
Ponding Ponding
Flow regulation: Inflow must be non-erosive sheet flow (3 feet per second for grass cells) Flow regulation: Inflow must be non-erosive sheet flow (3 feet per second for grass cells) or use energy dissipating devices. Bioswales can be used effectively in areas with slopes of 2 to or use energy dissipating devices. Bioswales can be used effectively in areas with slopes of 2 to 5 percent by installing check dams to prevent erosive flow velocities; slopes between each check 5 percent by installing check dams to prevent erosive flow velocities; slopes between each check dam should not exceed 2 percent. dam should not exceed 2 percent. Shallow ponding area: Drainage area should be less than 2 acres. Ponded water must Shallow ponding area: Drainage area should be less than 2 acres. Ponded water must completely drain into the soil within 24 hours, with 12 hours preferred as a safety factor. completely drain into the soil within 24 hours, with 12 hours preferred as a safety factor. Ponding depth should be less than 12 inches, 9 inches preferable. Ponding depth should be less than 12 inches, 9 inches preferable. Soil Type: Soil testing should be performed at the site by a licensed soil scientist or geological Soil Type: Soil testing should be performed at the site by a licensed soil scientist or geological engineer to determine the infiltration rate of the in-situ soils. Bioswales should not be used in sites engineer to determine the infiltration rate of the in-situ soils. Bioswales should not be used in sites with highly erodible soils unless turf reinforcement is used. The soil media within the bioswale should with highly erodible soils unless turf reinforcement is used. The soil media within the bioswale should be highly permeable and have an appropriate amount of organic material to support plant growth. be highly permeable and have an appropriate amount of organic material to support plant growth. Vegetation: Bioswales are typically planted with grasses, shrubs, and trees that can withstand Vegetation: Bioswales are typically planted with grasses, shrubs, and trees that can withstand short periods of saturation followed by longer periods of drought. Native plant species or hardy short periods of saturation followed by longer periods of drought. Native plant species or hardy cultivars that are not invasive and do not require chemical inputs are recommended. cultivars that are not invasive and do not require chemical inputs are recommended. Media layers: Media depth must be a minimum of 2 feet. The soil media must comply with the Media layers: Media depth must be a minimum of 2 feet. The soil media must comply with the city’s Storm Water Standards. If existing soils do not meet the criteria, a substitute media must be used. city’s Storm Water Standards. If existing soils do not meet the criteria, a substitute media must be used. Underdrain system: An underdrain must be installed if the current soil drainage is less than Underdrain system: An underdrain must be installed if the current soil drainage is less than 0.5 in/hr. The underdrain pipe should be at least 6 inches in diameter and installed at a 0.5 percent 0.5 in/hr. The underdrain pipe should be at least 6 inches in diameter and installed at a 0.5 percent minimum slope. An underdrain must be installed if the bioswale is within 50 feet of a sensitive, steep minimum slope. An underdrain must be installed if the bioswale is within 50 feet of a sensitive, steep slope. Clean-out pipes must be provided if underdrains are required. slope. Clean-out pipes must be provided if underdrains are required.
To access the complete San Diego Low Impact Development Design Manual, visit: To access the complete San Diego Low Impact Development Design Manual, visit: sandiego.gov/stormwater/pdf/lidmanual.pdf sandiego.gov/stormwater/pdf/lidmanual.pdf To access the Storm Water Design Standards Manual, visit: To access the Storm Water Design Standards Manual, visit: sandiego.gov/development-services/news/pdf/stormwatermanual.pdf sandiego.gov/development-services/news/pdf/stormwatermanual.pdf To report storm water pollution, call (619) 235-1000 To report storm water pollution, call (619) 235-1000 thinkblue.org This information is available in alternative formats upon request. Printed on recycled paper thinkblue.org This information is available in alternative formats upon request. Printed on recycled paper