The Role of Construction Quality Assurance (Cqa) in Sediment Remediation
Type:
Presented during:
WODCON XVIII - 2007 Orlando, Florida, USA
Authors:
Hedblometal
Abstract: The St. Louis River/Interlake/Duluth Tar (SLRIDT) Superfund Site is located in Duluth, Minnesota, on the St. Louis River, an estuary and international port at the southern tip of Lake Superior. Its three bays contain approximately 400,000 m3 of fine-grained sediments, contaminated with polycyclic aromatic hydrocarbons at concentrations up to 35,000 mg/Kg. The selected response action includes dredging with on-site disposal and capping. This paper describes how quality is assured during the complex construction of the remedy.
Once contractors are selected and the remedy is ready to be implemented, the Owner is best served by a third-party who measures compliance with performance or method specifications and monitors environmental conditions during operations. While this role can be seen as adversarial, in the best of conditions the construction quality assurance (CQA) engineer provides independent measurements of performance useful to both the contractor and the owner.
This paper describes the CQA activities and values brought to a contaminated sediment remediation project. Documentation of compliance with specifications on supplied materials capping, dredging, best management practices, water treatment, water quality controls, geotechnical instrumentation, environmental restoration, surveying and effects on air, water and noise during remediation provides value to contractors and owners alike.
At the SLRIDT Site, these activities are detailed in a Quality Assurance Project Plan (QAPP) and a Construction Quality Assurance Plan. This paper describes the types of issues that arise during construction that are best managed in real time by collaborative work and timely attention to the details of construction as they compare to project requirements.
Matters covered include: site security, remote video documentation, material testing and acceptance surveying, sand cap layer placement thickness verification and approval, sheet pile and pipe pile placement, rock fill dam construction, consolidation evaluation, foundation stability, normal dredge residue management, dredge prisms, water quality, air emissions and noise monitoring.
Keywords: Dredging, capping, polycyclic aromatic hydrocarbons (PAHs), contaminated sediment remediation, contained aquatic disposal (CAD).