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Related Articles


Waterproofing Catch Basins

Waterproofing Catch Basins

Waterproofing Catch Basins

Hi All,
I am working on a 140 unit condo project that has offsite street improvements. We are proposing sump and on-grade catch basins which get built prior to onsite. The outlet SD pipes from CB's drain south through the site that get built with onsite improvements. My question is, as the offsite street and catch basins get built first, how do I prevent the storm water from getting into the catch basins, specially the sump CB? Is there a way to temporarily waterproof the CB (not just providing the filter fabric and sand bags?


RE: Waterproofing Catch Basins

If your system will be in place why don't you want runoff reaching it? If you cannot allow runoff reaching the system then maybe write a specification stating that no flow shall be allowed in to storm drain system prior to xxxx. Leave it up to the contractor or prepare separate plan showing how. Contractor may dam up around inlets, put a piece of plywood over the CB or divert flows. If diverting flows, make sure in specification that the diverted flows do not adversely impact anyone.

RE: Waterproofing Catch Basins

thanks gbam. I can not have water get into CB as there is no way for the water to drain out as the outlet pipe will not be constructed at the same time.

RE: Waterproofing Catch Basins

How big(internal volume cubic feet) are the CB's? and how many?

Richard A. Cornelius, P.E.

RE: Waterproofing Catch Basins

There's two of them.. One's 4 ft wide x 3.5 long (in the Sidewalk) x 6 ft deep on grade and the other is 10 ft wide x 3.5 ft long x 6 ft deep in sump. The first one captures 1.2 cfs and the big one 10 cfs (Q100).

RE: Waterproofing Catch Basins

One can place plates over the inlets with sandbags to "seal" them from sediment, but I wouldn't be too worrried about water getting in - they are made for that. The pipe stubs or openings would need to blocked as well.

My bigger curiosity is what happens to the surface water at the sumps if the basins are not functioning?

RE: Waterproofing Catch Basins

Get some biggg tire inner tubes. Put them in the CB and inflate to fill the space. When time comes to actually hook them up, deflate the tubes

Richard A. Cornelius, P.E.

RE: Waterproofing Catch Basins

Water is going to pond up and spill over the curb onto onsite which would be rough graded at that point of time with a silt fence at the ROW behind the Catch Basin. I think it would also pond the half street that we are improving.
May be I am overthinking, It does not really rain in California anymore :)

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