Harris County Flood Control District Site Stabilization and Revegetation Carolyn White, CPESC Stormwater Quality Department Clean Waters Initiative Wednesday, March 23, 2011
Presentation Outline HCFCD Mission and Overview District Support Programs Water Quality Program Site Stabilization and Revegetation Program District Landscape Practices Soil Amendment Study Revegetation Program Refinement
District Mission to provide flood damage reduction projects that work with appropriate regard for community and natural values.
Water Quality Program State and federal regulations provide impetus to implement WQ Program (Phase I MS4 Permit). Incorporate water quality enhancement features into project designs, where practicable. Improve storm water quality management in the Houston region. Systematically evaluate BMPs implemented on regional basis. Contribute to the national effort of assessing and quantifying BMP effectiveness. Refine applicable design criteria based on monitoring data.
MAP WQ Enhancement Facilities
Water Quality Monitoring Preliminary Data Mason Creek Detention Basin
Revegetation Program Goals Design and maintain stable sites to promote infiltration and manage runoff. Reduce sediment and other pollutant loading. Manage and develop soils on new construction and large-scale maintenance project sites. Create stormwater treatment wetlands within wet bottom detention basins. Create riparian corridors within flood control channels. Create diverse habitats. Reduce maintenance costs.
Revegetation Program Wetlands Coastal Prairie Riparian Corridor Reforestation
Revegetation Program Incorporate Soil Management & Revegetation considerations in all stages of a project. Planning regional criteria, concept landscape plan, identify multi-objective uses and interested parties,. Engineering/Design soil assessment, draft Revegetation Plan, draft O&M Manual. Construction Inspection, site-specific soil analysis, site stabilization, final Revegetation Plan. Soil Development & Vegetation Establishment soil management, turf & plant establishment, final O&M Manual. Maintenance & Monitoring Implement O&M, monitor and correct actions, site certification.
Project Planning
Project Design
Project Construction Site Preparation Site Inspections Soil Preparation
Turf Establishment
Tree Planting
HCFCD Trees per Year
Constructed Wetlands Pollutant removal through: Settling Filtration Infiltration Biological uptake & conversion Volatilization
Wetlands Planting
Wetlands Planting
Coastal Prairie Planting
Wildflower Planting
Project O&M Address site erosion as it occurs utilize soil erosion inspector to address problems. Develop adaptive management strategies to maintain complex sites. Coordinate with partners to define roles and responsibilities. Create Restricted Maintenance Zones for special areas.
Regional Challenges Approximately 650 sq. miles of HC is within Lissie Fm. Equates to about 825 miles of channel or 1,650 linear miles of slope. Poor Soils (silty clays, sodic, dispersive clays). Intense Rainfall (40-50 in/yr) Large scale maintenance activities. Erosion, erosion, erosion.
Soil Amendment Study Evaluate selected composted materials for stabilization of earthen drainage channels. Study site located at the southwest edge of Houston along Interstate Highway 10 in Lissie Formation. Standard trapezoidal Channel with a back slope swale system; side slopes of 3:1 (h:v) grade; 40 feet slope length.
Soil Amendment Study Amendments applied at a rate sufficient to add 0.5% O.M. to top 6 in. of soil: Pelleted chicken litter and newspaper (Ckn) Composted yard waste mulch (YWM) Coarse ground native wood chip mulch (CWM) Double ground native wood chip mulch (DWM) Manure compost (spent mushroom soil) (Msh) Composted cotton gin trash (CGT) Amendments incorporated using a rota-tiller, and the plots were seeded and culti-packed. To inhibit seed movement in the event of a storm, a tackifier was applied.
Methods
Results Runoff volume was decreased from 2 to 9 times over the control. Runoff reduction calculated to be: 182 to 324 gal/min/acre, or 3.6 to 6.0 million gal/min Houston does not have to transport or store that volume of runoff during a design storm of 3.5 in/hr Sediment load was reduced by all treatments over the control plot by 2 to 5 times. Sediment reduction calculated to be 28 to 1,300 tons per acre.
Program Refinements Develop cost effective specifications targeted for soil conditions. Address soil handling during and immediately following construction. Provide soil erosion monitoring & corrective actions. Establish more native grassland & prairie habitat. Fine tune maintenance relating to site conditions. Promote Low Impact Development. Design regional drainage and detention projects that incorporate water quality enhancement features.
Low Impact Development Runoff volume reduction is key factor in stormwater quality enhancement. Pollutant loading reduction achieved through green infrastructure. HCFCD and HC developing Low Impact Development & Green Infrastructure Design Criteria for Storm Water Management
Corridor Channels Natural channel design. Maximize stream functions. In-Stream BMPs to enhance water quality within the channel and floodplain. Habitat enhancement. Recreational and educational opportunities.
Acknowledgements Glenn W. Laird, Environmental Services Division Manager Catherine Elliott, Stormwater Quality Department Manager Robert E. Snoza, Water Quality Monitoring Project Manager Jonathan W. Holley, Water Quality Design Project Manager Dan Schertz, Stormwater Quality Technican Dr. Sam Feagley & Team, Soil and Crop Sciences, Texas AgriLife Extension Service
Questions? www.hcfcd.org carolyn.white@hcfcd.org 713-684-4128