HAMER Dewatering of excavations
Hamer is a company that specializes in dewatering of construction excavations.
We offer reduction of groundwater table through assembly wellpoint instalation or deep well drilling.
We provide comprehensive dewatering service:
- dewatering design/aquatic legal surveys,
- delivery and assembly of installation,
- supervision of dewatering,
- monitoring of groundwaters level.
We dewater excavations:
- linear for setting installations: sanitary, rain, electric, pipelines,
- wide-spatial for foundation residential objects with underground part,
- point for setting pumping station, foundations for windmills, foundations for power poles, fundamental alloy of steel structures.
Main applications of wellpoint instalations
Wellpoint instalations are used primarly for reducing of groundwaters level. Most often used for dewatering of engineering and construction excavations.
The following uses can be indicated:
- periodic dewatering – reduction of water level for construction and engineering works demanding excavations that reaches below groundwater natural level,
- dewatering of construction excavations,
- general reduction of groundwaters level,
- geotechnical dewatering: reduction of water level to reach bigger consolidation and soil stability, reduction of landslides etc.
Wellpoints ended with filter are positioned in ground and are points of water intakes. They enable acquistion and draining water from ambient area.
Depending on the ground conditions and requirements, end of the wellpoint is usually at 4-6m depth. Above the level of ground wellpoints are connected with commutator ( in case of installation IgE 81 placing in spigots of commutator sealed with a gasket O-ring type).
Series of commucators is connected to each other with the use of additional elements of installation such as bows, connectors and through pipe. Series of commucators are linked to pump aggregate. Aggregate has pump or pumps allowing production of underpressure in installation. Obtained underpressure, while maintaining tightness in installation allows collection of water from ground. Collected water is expelled through aggregate and directed through pipeline or discharge hose.
It is assumed that one level of wellpoints allows reduction of water level to 4m. Due to shape of created depression funnel, end of wellpoint should be placed in 1-2m below expected depth to which level of water should be reducted.
Jetting of wellpoint
Wellpoints placing in ground is implemented by induction process. Necessary in it is introduction through jetting hoses which bring a stream of underpressured water to jetting pipe. That stream allows easy introduction of jetting pipe deep into the ground. Depending on the type of soil wellpoints rinses off with or without backfill.
Filtering backfill is made:
- in layered soil ( with impervious layers ) at such a height that backfill connects all levels of dehydrated soil, most often on the entire rinse height of wellpoint,
- homogeneous soil, silty at 0,5m over top edge of wellpoint ( practically two buckets of backfill).
After pipe introduction to soil, jetting hose is disconnected and a wellpoint is introduced into the pipe. After wellpoint introduction, jetting pipe is pulled out from the ground. Jetted wellpoint can then be connected to suction commutator.
Drilled well with circular cross-section, about diameter 300mm, stocked with submersible pump, fathmoed to reduct pressure or groundwater table in the excavation zone. Parts of the well are: filter column, pebble backfill and submersible pump.
After pumping, the holes are closed. Drilled wells are used to dewater in difficult soil conditions or at considerable depths, where using of wellpointed aggregates is impossible.