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Robert Lamoureux: Water in the vault can result from faulty pump

Posted: February 13, 2009 11:02 p.m.
Updated: February 14, 2009 4:55 a.m.
 

Dear Robert:
We’ve got a problem in our underground parking area. There is one area that is about 6 feet by 6 feet that fills up with water under the grate whenever it rains, and water is coming up through the other drains which becomes very slippery and hazardous. We have a maintenance man that says the lines are clear, but we are still having this problem. So, if the drain lines are clean, what else can we do?
Joyce B.

Hi Joyce,

You must live at a very large property.  This 36-square-foot grated area that you are talking about is your vault. With a vault that size, it’s probably about 8-feet deep with four big 10 hp pumps at the bottom — two primary and two secondary.

Once these pumps stop working, the vault fills with water and instead of discharging out to the main, the water is flowing out through the other drains.

You’ve probably got a lot of mud, oil and muck at the bottom of that vault that has choked the pumps and has shut them down. Part of routine maintenance of these vaults is to have them pumped out and cleaned every two or three years. You can’t pump this out yourselves, it has to be done by an environmental company which works together with the Health Department.

Since there is usually motor oil and asphalt oil in there, it becomes what they call environmental waste.

It’s a Hazmat issue of contaminated waste so you can’t just clean it out and throw it away. The environmental company will send out a truck which will pump out all of that sludge then take it for safe disposal. Most of them use the dumping facility in Gardena.

Then there is a sample that’s taken and you are charged based on the weight and what they find in that sludge. You are invoiced after the testing is done.   

If you don’t keep the vault clean, all that gunk is pulled through the pumps which could burn them out. 

Once you get the vault cleaned out professionally, run some clean water down in the pit and clean them out to see if they start working.

If not, they have to be hoisted out of there which is not an easy job. It takes two men just to lift a grate that size.  After the pumps are hoisted out, take them to a motor company that will tear them apart to see what they need for repair. They won’t be able to give you a price until they open them up. It might only be the bearings or the impeller on the outside of the bell housing, but you won’t know until they take a look at it.   

The number and size of pumps needed at a property are calculated on surface area times 1 inch of rainfall per hour. With the size of your vault, these are big pumps, probably with six-inch outlets. They can move a lot of water and mud, but you don’t want them sitting in sludge.

Call an environmental company every 2 or 3 years to keep the vault and pumps clean.  This is a costly endeavor, about $2,000 for that size vault, but that is much less than the liability of someone slipping in the water, potential water damage to your property and the cost to repair or replace the pumps.

Hi Robert:
I enjoy your column. This is the first time I’ve written in. We have some flooding in the common area of our condominium complex and the contractor suggested that we install some new drains above our parking garage. He also said that he needed to x-ray the concrete before he drilled for the new drains which is a very costly procedure. Do you think the x-raying necessary?

Jim C.


Hi Jim,
Absolutely. There is no way I would core through the concrete of a podium slab without x-rays. If the slab is 18 inches or thicker, the x-ray lab will come in with cobalt. It is contained in a cart that weighs about 700 lbs.

The cart is wheeled on top where the coring is to be done. Underneath in the parking garage, a man places the film, the slide, up against the ceiling held in place by a retractable pole directly under the cart.  

To make sure they line up the film and the cart, they will ping the slab. A man on top will hit the concrete will a hammer, while the man underneath in the garage will listen and get a general idea of where the cart above is located. Once they get close, they will bring out a very powerful electromagnet that will shoot through the concrete. The man in the garage will have a piece of sheet metal and when it holds to the ceiling, he knows exactly where to place the film for the x-ray exposure.  

The cart has a door on the bottom that is operated through a remote switch attached to a cable about 150 feet long. When ready, the men will un-roll the cable and walk it around the corner to avoid exposure to the cobalt, open the door, and take the x-ray and then close the door. Depending on how many drains are to be installed, this process is repeated at every separate area that needs to be cored.

The cobalt exposure will cause no residual effects to plants or food, but as a safety concern, all residents within 75 in every direction of each core site needs to vacate their property until finished. If the walls of the buildings are concrete, depending on their thickness, the x-ray lab can put up shields for protection as near as 50 feet away, but as a rule of thumb, everyone within 75 feet must leave.  

To save money, there have been times when members of the BOD have said they would exonerate us and not hold us liable for any possible damages if we were to core without x-rays. No thank you. The reason why we are so cautious is we never know what is buried in the concrete. It could be post tension cables, or steel or electrical.

If we were to cut through a PT cable, it could rip out through that concrete and cut a man in half.

If we cut through electrical, like a home run, our men could be electrocuted. Even if no harm was to come to our men, the damages from cutting the PT cable or home run would cost the national debt to repair.

This is something that we do not take chances with, period.  

After the film is exposed, they take the slide to their truck, a mobile lab, and develop it on the spot.  From this we can see if it’s safe to proceed. If not, another location is selected and the process is repeated.

Robert Lamoureux has 25 years experience as a general contractor, with separate licenses in electrical and plumbing contacting. He owns IMS Construction Inc. in Valencia. His opinions are his own, and not necessarily those of The Signal. Opinions expressed in this column are not meant to replace the recommendations of a qualified contractor, after that contractor has made a thorough visual inspection.Send your questions to Robert@IMSConstruction.com.

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