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Dewatering Bags Frequently Asked Questions

Dewatering Bags Frequently Asked Questions

What is Dewatering? 

Draining water from low-lying areas is a common objective in construction projects, particularly for damp or low-lying excavation sites where foundations are to be poured. There are several different means of extracting water from these areas, but the overall process is known as “dewatering.”


Why use an UltraTech Dewatering Bag? 

To protect the environment and meet local, State and EPA regulations. Some dewatering processes tend to remove a lot of dirt, silt, mud, and debris along with the water. These contaminants can cause problems if they are simply discharged into storm drains.

An appropriate dewatering bag—into which water from the low-lying area is pumped—is designed to filter out silt, dirt, sand, and other pollutants by trapping them so that only water escapes to the ground below or into nearby storm drains. As an added benefit, the UltraTech Ultra-Dewatering Bag also traps oil, and is available in several sizes ranging from 3’ to 15’. The bigger the bag, the longer the life (and less need to frequently check and replace it).

Dewatering bags are deployed by laying them on an area of ground that can absorb the water being removed from the low-lying area. They connect to the pump via a common discharge hose. To increase the efficiency of filtration, place the dewatering bag on an aggregate or hay bale bed.

In any case, be sure to observe local, state, and EPA regulations related to the discharge of water from your dewatering operation. 

The total flow rate through the Dewatering Bag can be maximized by getting it off the ground. While water will flow through a Dewatering Bag lying flat on the ground, it will be impeded by the solid/saturated soil it is on. By placing the bag on large aggregate or on hay bales, the water will be less restricted as it flows through the bottom layer of geotextile fabric.


What is the flow rate?  

The maximum flow rate of the Ultra-Dewatering Bags, when new, is 500 gallons/min. For more information, check out our specifications. 


What should I do with the bag when it's full or I’m done dewatering? 

When the Dewatering Bag is full, it should be disposed of as directed by the site engineer and in accordance with any local regulations and requirements. Often, it can simply be cut open and the contents dispersed.


I need a Dewatering Bag in a size that is not listed.  Can you make that for me? 

Yes, we can do custom sizes (and shapes). Please just ask us for a quote.


How do I secure the Dewatering Bag to the discharge hose?  

If your flow rate is not too high, you can use the attached straps to tie off the bag to the hose. If water is being discharged at a higher flow rate, a hose clamp may be required (not included). You can also use our optional Hose Connector (Part# 9739) to make the connection quick and easy.


Can I get custom dewatering bags? 

Yes - Contact Interstate today at 1-800-474-7294 for help.

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