Construction Dewatering

Carbonair has extensive experience providing rental groundwater treatment systems for treating contaminated groundwater generated by dewatering operations on construction sites. We recognize that contractors need to focus on completing their scope of work on construction projects and don’t need to expend time and energy dealing with a water treatment system that can be hard to manage and operate. Carbonair can provide contractors with well-designed groundwater treatment systems that will operate with no down time and offer the experienced field staff to provide the support needed to get the job done.

Project Examples: Groundwater Treatment Equipment Rentals for Construction Dewatering

Groundwater Treatment System Rental in support of a Highway Construction Project

As part of a major highway improvement project, construction dewatering was required in an area in order to pour footings for an overpass. Contaminated groundwater 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.

Challenges for this project included:

High dewatering flow rate required (3000 gpm)
Small area on site for treatment system adjacent to operating highway
Short lead time for set up of system
24 hour operation required

Carbonair designed and provided a 3000 gpm groundwater treatment system consisting of three (3) 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 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. The systems were mobilized, installed and started up in less than five business days from the notice to proceed. The actual field installation took three and one-half days.

The 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 system and was able to safely deliver, set up and then demobilize the 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.

Groundwater Treatment System rental in support of Brownfield Construction Project

A mid-Atlantic environmental firm contacted Carbonair to develop a treatment system for a Brownfield development project. Three office complexes were being built in downtown Washington DC. Each building included underground parking, requiring excavation 65 feet below grade.

Groundwater samples revealed BTEX and TCE contamination, and hydrological testing indicated pumping rates of 1000 GPM would be necessary to allow construction to resume.

Water treatment system design challenges on this project included:

A high water flow rate (1000 gpm)
Limited space on site for system
The need to move the system periodically to allow for site work
24 hour operation required over a long period of time
The need to exchange media in vessels while maintaining a 1000 gpm flow rate
The potential need to downsize the system based on reduce flow rates in the future

For this project, Carbonair designed a modular 1200 GPM water treatment system consisting of twelve 100 GPM units on a common header. Each unit had a duplex bag filter skid and a Carbonair PC13 carbon absorber. Carbonair furnished the complete system, including hose, fittings, headers and valves. Carbonair’s field service team installed the system and trained the operating personnel.

This modular design allowed the system to continuously flow at 1000 gpm, while two vessels could be held in reserve and serviced if needed.
Using a modular system with multiple small carbon vessels resulted in less site preparation time prior to installation, when compared to larger vessels.
Due to extreme space restrictions, the system had to be moved several times during the course of the project. This was simplified by the compact, flexible design employed.
After 14 months of operation, site conditions changed allowing for a reduction in the required flow rate. Carbonair was able to easily reduce the size and operating cost of the system, by simply removing several of the 100 gpm modules.

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