The traditional planning approach for watershed restoration that is based on stormwater management retrofits has typically been based on the use of creating large scale centrally located ponds and BMP structures, or designing individual Low Impact Development and Green Infrastructure practices to capture and treat the largest amount of stormwater that can be captured by the facility. This approach requires large scale disruptions to the existing infrastructure or impacts on natural areas in order to construct and accommodate the BMP/LID/GI facility footprint. The Public private Partnership (P3) planning approach is a “top down” and integrated approach. Corvias has developed a comprehensive approach that looks for opportunities throughout the watershed, but focuses on the upper part of the drainage areas.
The approach targets small scale drainage areas where the most effective and appropriate types of BMPs can be replicated and quickly and easily constructed and maintained by local contractors. Our first step is to develop design templates that can be applied to typical retrofit conditions throughout the watershed. These planning and BMP design templates, or strategies, have been developed to allow local engineers to quickly identify opportunities and appropriate BMPs that address the targeted watershed restoration goals. We are constantly evaluating the BMP implementation strategies on our metrics of the control of the volume and the filtering of stormwater, local economic and jobs creation, maintenance, and a variety of other factors that we develop with the local government team. Our team of designers, construction managers, outreach specialists, and procurement staff can then quickly evaluate and phase the implementation of the restoration and respond to evolving community goals and regulatory restoration requirements. Here is a brief description of the types of representative opportunities listed in the typical watershed schematic exhibit that are used in the restoration strategy:
County, Municipal, and Public Properties
This category includes schools, libraries, public buildings, maintenance facilities, parks, and other community facilities. Our team works with the local government staff to identify appropriate types of practices that increase educational, economic development, and community enhancement values for the properties.
Alternative Compliance Program
This program was developed to help reduce the impacts of taxes and utility fees for faith based organizations. These properties are excellent opportunities to construct BMPs because of the typical conditions of large scale parking lots and building impervious areas. We work with each individual organization on coordinating public outreach and stewardship as part of the implementation plan.
The sheer number of existing outfalls that require reconstruction to current erosion and sediment control and stormwater management standards in existing urban areas presents an opportunity to quickly deploy cost efficient and environmentally effective stabilization techniques that have a small construction footprint and short time for planning and construction.
Regenerative Step Pool Storm Conveyance
Regenerative Step Pool Storm Converyance (SPSC) systems are used where there is a larger area of construction available at the outfalls and there are sufficient upstream BMP controls so that the SPSC can enhance or compliment the upstream efforts.
Street Sweeping and Catch Basin Cleaning
Wider streets with more traffic generate large amounts of street dirt and trash. Regular sweeping and catch basin cleaning are effective methods to reduce the amount of pollution that is discharged without treatment or to a downstream BMP.
Strategic planting of trees on existing open space reduces stormwater impacts as well as help enhance open spaces, property values, safety, and air quality.
The conversion of existing extended detention ponds and enhancement of existing wet ponds allows for the treatment of large areas of imperviousness without impacts on surrounding properties and environmentally sensitive areas. The goal of these designs is to treat the impervious areas as well as provide “uplift” and enhancement of existing and potential wetland and habitat areas in and around the facilities.
These projects are used to retrofit streets in high community and economic development value. The combine the use of LID techniques, such as permeable pavement parking areas, bioretention, and street tree planting to create signature and focal areas within the community that promote safety and overall air, energy, and environmental sustainability.
Low Impact Development and Environmentally Sensitive Design
Low Impact Development and Environmentally Sensitive Design (ESD) is a network of small scale BMPs that have a small footprint that requires minimal time for construction and are used to enhance the appearance of the local public streets are constructed at the upper part of the watershed. These include bioretention, grass swales, and bioretention swales.
These are used in local public streets to treat stormwater for larger drainage areas and to treat a specialized range of pollutants.
This technique is used in the upper portion of the watershed to compliment the use of BMPs, Outfall Protection, and SPSC. These are targeted for use in headwater streams and where there is appropriate disturbance of natural areas and when impacts to sensitive environmental areas can be avoided.