Throughout the Master Plan process, the community expressed concern about the condition of the Alapocas Run and the need for a regional stormwater management system. The project team committed itself to working with the review agencies to address these concerns. The result is an integrated stormwater management, wetland mitigation and landscape plan that improves the quality of the water and related resources throughout the Blue Ball Properties Transportation Area.
- Wetland Replacement
Wetlands play an important environmental role in groundwater recharge and recycling. Because of this, any wetlands lost as a result of development must be replaced within the same watershed. The current preliminary design displaces approximately one acre of wetlands. Two acres of wetlands will be built in the project area in combination with a mitigation package including stream restoration, wetland encroachment and riparian buffer enhancement.
The wetland replacement site was chosen based on water circulation and soil conditions that make it suitable for wetland plant material. Native wet plant material will be combined with stormwater management efforts and other compatible plants
- Streambank and Channel Restoration
Some areas of the Alapocas Run will be restored using natural channel restoration techniques and plantings. The intent of the restoration effort is to construct a natural looking and stabilized stream channel that will provide suitable habitat for species native to the stream and related areas. The restored channel will be constructed using native materials such as rocks, boulders and stream gravel, and the new stream banks and adjacent forest areas will be planted with native shrubs and trees.
Approximately 1260 feet of the Alapocas Run will be improved by the project. The channel restoration effort is being conducted in conjunction with additional storm water management controls to reduce the volume and speed of storm water throughout the system.
- Buffer Enhancement
The stream buffer zone along Alapocas Run, south of Rockland Road, will be enhanced in an effort to improve water quality and aesthetics. Adding plants will cool the stream and stabilize the stream banks, thereby improving aquatic habitat conditions.
- Stormwater Management System
Stormwater management for the Blue Ball Properties development is based on an integrated approach comprised of:
- Alapocas Run stream restoration
- Bioswales for water quality enhancements
- Riparian buffers
- Native landscaping
- Wetland mitigation
- Three new detention basins which will work in concert with two existing basins on the AstraZeneca parcels.
Detention Basins 1, 2, and 3:
- Collect stormwater from Westside transportation features and the previously unmanaged Independence Mall drainage area
North and South Basins:
- Reduce stormwater runoff from AstraZeneca into Alapocas Run
Enhanced stormwater collection reduces flows in Alapocas Run:
- Approximately 35% for 2 year storms
- Approximately 8% for 10, 50 and 100 year storms
Reduced flows combined with stream restoration enhances water quality of Alapocas Run.