Dewatering and sheetpiling division

Sheet Piling

​Structural Integrity

​Shoring: Wooden & H Beam Shoring

​Dewatering: Deep Well System

Design Criteria

​Groundwater Management

​Advantages

Technical Background

​Dewatering: Well Point System

dewatering: well point system

Well Point Systems are commonly used De-watering method as they are applicable to a wide range of excavations and groundwater conditions.

Methodology 
Well point De-watering systems are installed around the perimeter of the site against excavation shoring and are coupled with a perimeter discharge line via a pump set. Various pump sets are available specific to the site requirement. For a well point De-watering system to be effective, the ground sub strata needs to generally be permeable to allow the well points to draw the groundwater. To achieve the best outcome for the builder, GEOMAC consult with the relevant environmental consultant and the soil reports provided by the builder. 


Advantages 
  • Quick Deploy 
    GEOMAC can efficiently and effectively put a well point system in place to reduce construction downtime. Our experienced team has the know-how to do this with minimal construction downtime to the builder. 
 
  • Cost Effective 
    Well point systems and ancillary De-watering equipment can be hired for short and long periods of time, and individually, to cater to the builders De-watering requirements.
 
  • Effective, Economical 
    For construction sites where deep well De-watering is not required, GEOMAC well point (also known as spear point) De-watering system is an effective and economical way to reduce the level of the water table to the required excavation level. 
 
  • Technical Background
  • Site De-watering is commonly required when excavations are required to extend beyond the ground water table. For shallow excavations (generally under 4 meters) well-point De-watering is often the most efficient method to achieve an adequate draw down in permeable soils. (i.e. sand, clayey sand, etc.) 

    PVC spears (well points) are jetted around the site perimeter from ground level and later connected to a common header pipe. These spears draw water (under vacuum) from beneath the excavation. The water is then discharged in accordance with a De-watering Management Plan (DMP), which is a requirement for the client to have prior to commencing De-watering. 

    A filtration process is often required depending on the water quality at the discharge point, and the findings of the soil reports engaged by the client. 

    GEOMAC can offer comprehensive De-watering packages which include a De-watering plan, equipment specification and recommendation, filtration and groundwater monitoring. This is completed with the builder and the relevant environmental consultants. GEOMAC is committed to the environment. 
 
  • Design Criteria 
    GEOMAC will provide you with technical assistance for the selection of the most efficient method for your particular job or site. We will then manage the system, leaving you to enjoy the cost savings and allowing you to carry on with the rest of your building and construction requirements.
 
  • Groundwater Management 
    The main objective in any De-watering exercise is to lower the water table below the working platform and maintain the depressed level economically and efficiently for the duration of the De-watering period. 

    The sub-strata and its permeability in and around the site will determine which type of De-watering system will be most effective. This, in turn, will allow GEOMAC to formulate the number and size of wells required to reduce the water table for excavation. Positioning may also be conditioned to suit the builder’s construction requirements. Groundwater management involves strategic positioning of well points to provide a dry working platform and to limit the effects on the groundwater table (GWT) beyond the site. The depressed water table forms a level of depression between the natural GWT and the well points. The extent of local reduction in the water table is dependent on the well point depth, amount of well points used, the positioning of the well points and the permeability of the soil. From the natural GWT depicts the De-watering of a typical high-rise site.
 
  • Area of Application
    GEOMAC will provide you with technical assistance for the selection of the most efficient method for your particular job or site. We will then manage the system, leaving you to enjoy the cost savings and allowing you to carry on with the rest of your building and construction requirements. Our GEHO type ZD900 is a twin cylinder, quadruple acting crankshaft driven vacuum piston pump. The crank timing produces a moderate pulsating type action that prevents clogging of the well point strainers and achieves priming from greater depths. Up to 100m3/h constant capacity water, air or water and air mixture are primed and discharged against a head of 20 meters.