# Heavy Construction Tips/Techniques/Shortcuts



## jmacd (Jul 14, 2009)

> When building deep manholes or lift stations:
> 
> Put 3' to 4' of water in the bottom, or sleeve a relieve valve in the base to keep the box from floating out of the ground


Same with septic tanks.

When running conduit under under sidewalks use a piece of steel pipe larger than conduit and push pipe under sidewalk. Then pull pipe out the other end and push plastic conduit in it's place.


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## JDavis21835 (Feb 27, 2009)

Sar-Con said:


> When building deep manholes or lift stations:
> 
> Put 3' to 4' of water in the bottom, or sleeve a relieve valve in the base to keep the box from floating out of the ground.


Had one last august that we had to sink. We were 30 feet deep with a pc400, benched down 15 feet. The last 15 feet of cut was in wet sand, and the project had us keying into clay. We knew it would be wet as we were building a groundwater collection system. The banks were giving us enough water 2 2inch pumps, and 1 3 inch pump were barely keeping up. About the time we were ready to swing the base section in we got a thunderstorm. 

Ive seen less water going over some waterfalls. Luckily for us, we were already on grade, and had stone in place. The base section floated for a good 5 minutes, while we tried our best to get things on line, and then we pushed the hole down to the stone, and let the base section fill with water. We shoved a sheet pile in front of the inlet, and stoned around the hole, put 2 more barrel sections in, and headed for the hills as it was friday afternoon.


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## HUI (Jan 21, 2011)

Places where you have a large diameter wetwell we have used a clam bucket to set the wet well when the water table is high. You order the wet well with a key way on the inside. And you bolt a piece of steel around the outside for a cutting edge. Then you dig out of the inside. The weight of the structure will push itself into the ground. After you have it to grade you pour your floor low. Wait a few days for the concrete to set. Then you pump out the inside and pour your finished floor.


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## dayexco (Mar 4, 2006)

HUI said:


> Places where you have a large diameter wetwell we have used a clam bucket to set the wet well when the water table is high. You order the wet well with a key way on the inside. And you bolt a piece of steel around the outside for a cutting edge. Then you dig out of the inside. The weight of the structure will push itself into the ground. After you have it to grade you pour your floor low. Wait a few days for the concrete to set. Then you pump out the inside and pour your finished floor.


what type of soil we dealing with here?


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## HUI (Jan 21, 2011)

I have done clammed down a wetwell in clay. I have seen it done in sand also. The largest determining factor is the ground water. Instead of using a large pit with slide rail or tight sheeting this has been a pretty good option.


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