Services

TerraFirma Earth Technologies, Ltd. specializes in the installation, maintenance, and operation of dewatering systems and equipment. We offer several services to help owners and contractors maintain acceptable groundwater levels for both temporary projects and permanent installations. We offer several services to meet this goal:

Based on a project’s geotechnical data, we will provide proposals based on the application of those services best suited to the task specifications.

WELLS

Deepwell Groundwater Control System

TerraFirma uses several different well designs to achieve efficient dewatering results. The most commonly used well is the deepwell. A deepwell consists of a borehole into which a well assembly (made up of casing and well screen) has been placed. The annular space between the two is filled with filter media. Within this well assembly, an electrically driven submersible pump and discharge column pipe are installed. These tie into a discharge manifold after they exit the seal at the top of the well. Usually valves are placed between the wellhead and discharge manifold to ensure minimal downtime if an individual well should require servicing.

Deepwells are often used in conjunction with relief wells. These wells consist only of the borehole, filter media, and the well assembly. The purpose of these wells is to aid in the draining of the soils, thereby making the integrated deepwell system more efficient at a lower cost. Sump wells are installed within the base of the excavation, when standing water is anticipated.

WELLPOINT SYSTEMS

Wellpoint Dewatering System Installation

Wellpoints are a common method of dewatering. They are cheaper than other methods, install quickly, and have rapid drawdown times. However, they are not capable of handling excavations deeper than about 25’ without benching in several levels. A typical wellpoint system includes a series of wellpoints (usually 1-2” PVC with a slotted portion at its base) connected to a vacuum header via a swingarm. The header is attached to a vacuum pump, which applies a vacuum to the system, and pulls in water from the wellpoints.

 

EDUCTOR SYSTEMS

While not as common as the previous methods, eductors are very effective at dewatering formations characterized by clay and silt. Eductors consist of the well assembly, into which an eductor body is placed above the screen. A high-pressure supply line pumps water into the eductor body, which creates a venturi effect, pulling water from the surrounding soils.

 

SYSTEM MAINTENANCE AND OPERATION

TerraFirma provides contractual maintenance and operation of all systems we install, as well as systems already in place. Our maintenance and operations solutions ensure that dewatering systems operate as they should, and that they produce the results as originally intended.

We will evaluate your current dewatering systems and propose a maintenance program. We work with our clients to find cost-effective solutions to bring neglected systems back online, and to prevent future deterioration.