Challenge
As part of a major highway improvement project, construction dewatering was required in an area in order to pour footings for an overpass. Contaminated water from an adjacent Superfund site was drawn into the dewatering stream, requiring treatment of the contaminated water stream prior to discharge on-site. Based on the large area being excavated, the high water table and the permeability of the soils, a flow rate of 3000 gpm was required to keep the excavation area dry during construction work. Carbonair first met with the general contractor and environmental engineer to work out the required treatment system design and assess site logistics for system layout, delivery and installation.
Solution
Carbonair designed and provided a 3000 gpm groundwater treatment system consisting of three (3 water treatment trains) individual 1,000 gpm treatment streams comprised of the following:
- A 21,000 gallon settling tank for the removal of large solids and free product
- Bag filters for the removal of suspended solids
- Granular activated carbon (GAC) filters with 30,000 pounds of carbon for removal of dissolved organic contaminants.
The construction dewatering systems were provided with all necessary components for operation in the field, including 30 horsepower transfer pumps with level controls, hose and fittings, distribution headers and a 100 kW generator for the system’s electrical power requirements. Carbonair’s treatment systems were mobilized, installed and started up in less than five business days from the notice to proceed. The actual field installation of this groundwater treatment systems took three and a half days.
Results
Carbonair’s construction dewatering systems performed as designed and allowed the contractor to finish the installation of the footings ahead of schedule, saving them, and the DOT, a considerable amount of money. Carbonair was able to meet their short lead time for delivery of the water treatment equipment and was able to safely deliver, set up and then demobilize these construction dewatering systems in an extremely tight area adjacent to an operating highway and with overhead power lines at the site. Demobilization was accomplished in just three days.