Rates, Norms & Durations / Building & Construction / Earthworks & Excavation
Dewatering
2 entriesSource page: Dewatering
Subjects on this page
| Activity | Entry (verbatim) | Source |
|---|---|---|
| Cofferdam Works | Soil Mix Wall Three auger machine drilling and mixing cement into three cores. H-piles dropped into two, then machine moves along by two holes. An average output was 4 - 5 m/day. | Cofferdam Works |
| Dewatering | To setup a cofferdam dewatering system, including boring, pump installation and outflow pipework and drainage tanks etc, typical rates are...Small 2 hole system, for an overrun tunnel, with a single drilling rig takes about 7 - 10 days to get up and running.A larger system, with 10 - 15 holes, for a station type cofferdam will take in the region of 3 weeks with 2 rigs. This can be speeded up with the use of more rigs to reduce the well boring times.A typical rate of 2.5 days per pump installation can be used to calculate detailed pumping arrangements. The water level can be dropped in a "closed cofferdam" within a 6 to 8 hour period for a 25,000 m2 cofferdam with a 2 m water level reduction. For smaller closed areas it will take only a few hours at most to reduce the water level by 2.5 - 3 metres.Recharge System - Average well depth of say 55 m deep, not into rock, 9 wells in 10 days or 1.11 days/no with an additional 4 - 5 days to connect pipework and recharge backup tanks etc.DewateringTask / DescriptionSlow Ave Fast Units Setup small 2 hole system10.0 8.0 6.0 days Setup large 15 hole system- 21.0 - days Calculate system times per pump- 2.5 - days/pump Setup Recharge System- 3.5 - days/pump | Dewatering |
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These values were contributed by members and reflect the conditions, methods and regions they worked in. They are a starting point for estimating, not a standard. Check them against your own records, the site conditions and the contract before relying on them.