Geddes Brook/Ninemile Creek: Years 1 and 2 Lessons Learned during Remediation of 1.5 Miles of Stream and 35 Acres of Floodplain

摘要

Background/Objectives. The cleanup of Geddes Brook and Ninemile Creek began in2011 and is anticipated to take 4 years to complete. Ninemile Creek and its tributary,Geddes Brook, are located northwest of the City of Syracuse, New York. GeddesBrook/Ninemile Creek has been impacted by past industrial pollution, relocated andchannelized by road and bridge construction, and populated largely by non-native invasiveplant species. The Geddes Brook/ Ninemile Creek Site includes approximately 1.5miles of channel and 35 acres of wetland/floodplain impacted from industrial pollution.The chemical parameters of interest for the site include mercury, lead, arsenic, totalPCBs, total PAHs, phenol, and hexachrolobenzene. The selected remedy for the site includesapproximately 200,000 cubic yards of soil and sediment removal along withextensive habitat restoration.Approach. During development of the design, a significant focus of the project team wasto identify how habitat restoration objectives could be integrated with the remediationgoals. At the same time, the selected remedy attempted to take advantage of practical approachesthat would be beneficial during implementation of the remedial action andultimately contribute to the long-term success and sustainability of the project. To facilitateeffective removal of the invasive species and allow for a clear removal horizonduring construction, the Geddes Brook design called for removal to the underlying claylayer. In addition, a restoration design was developed which improved sinuosity and increasedlength of the channel, improved connectivity between the channel and itsfloodplain, and provided invasive species control measures by using onsite clay materialsto shape the restoration subgrade, creating a civil mass balance minimizing disposal andbackfill costs.A portion of Ninemile Creek (approximately 1000 feet) is located immediately adjacentto industrial wastebeds. Due to steep side slopes along the wastebeds, there is littleto no riparian habitat zone in this area. The remedial action will re-locate the channel furtheraway from the wastebeds to facilitate a wider more productive riparian habitat zonewhile allowing for deeper removals in the areas of elevated impacts. The channel relocationalso provides other advantages including construction sequencing, habitat enhancement,and a more sinuous channel.