City Shops
City Shops
Based on lessons learned during the Constitution Park riverbank remediation and because of steeper riverbank slopes in this area, several design changes were made. A more natural looking stone was placed at the base of the riverbank to more closely match surrounding river rocks more closely. Like the Pilot Bank, the stone was placed throughout the length of the remediated riverbank to enhance protection at the base of the bank. The native trees and shrubs planted after construction are growing well and new trees are starting to grow from seeds deposited in sediment at the base of the bank. Although flooding has occurred, the remediated riverbank remained stable and no riverbank maintenance has been necessary to date. The native vegetation that was planted is thriving and natural recruitment of other desirable plant species is becoming more established, with limited invasive species such as Japanese knotwood.
Monitoring Data
For Phase I of this work, samples were collected at the two remediated riverbanks in this area and analyzed in a laboratory. Based on the laboratory results:
- Mercury levels have decreased in the sediment immediately adjacent to the remediated banks.
- Immediately after the remediation, mercury levels in the water between the grains of sediment (otherwise known as pore water) slightly increased. This increase is expected because the remediation work disturbs the banks. A similar increase occurred after the Constitution Park riverbank was remediated, and mercury levels in pore water began steadily decreasing about six months after remediation was complete.