Basements, Attics and Crawl Spaces - Crawl Space Drain Questions

I would like to install a drain system to intercept storm water once it makes it under the 12” x 30” spread footing for the retaining wall that separates the crawl space under our town home from our garage. We have been trying to get our HOA board and management company to come up with a solution to intercept the water before it enters our property, but we have not been successful in getting them to address the issue and we have to do something internally to protect our property since the winter rains have arrived.

One concern is to not relax the soil in front of the spread footing. Another is negotiating the piers for the posts. I only have about 6” between two of the pier footings so I am very limited as to what type of product I can use if I want to run a 24’ long trench drain parallel to the spread footing.

Because of the piers and their footings the closest the 24’ trench drain can run parallel to the spread footing is 30”. We are thinking of using the 12” product from MULTI-FLOW (http://www.varicore.com/Menu/residential_app.html). It only requires a 4” wide trench, creates minimal spoils and uses coarse sand instead of drain rock. Anybody use this product before? Are we approaching this correctly? Is a 30” spacing between the spread footing and the 12” deep by 4” wide trench drain sufficient? I don’t want lateral displacement of the retaining wall when the soil underneath and in front of the spread footing is saturated with water.

http://www.fototime.com/22553E1650D9D7F/standard.jpg

Thanks for taking the time to read my post and consider my questions.

Howard

In addition to the drainage trench, we have already created a gutter for the spread footing and retaining wall. Based on evidence from last year, we believe one of the areas water enters the crawl space is through the mortarless vertical joints in the first course of blocks and where the sanitary drain penetrates the retaining wall. The gutter will collect the water from these areas and divert it to a basin to be pumped out.

This is what our retaining wall and spread footing looked like after we removed the soil on top.

http://www.fototime.com/3E34C4D0D6D531B/standard.jpg

http://www.fototime.com/743B6E02BCFAF92/standard.jpg

We hired an excellent landscape company that does concrete and drainage work and I had them chisel out all of the over pour to expose the mortarless vertical openings and create a base for a concrete gutter.

http://www.fototime.com/59A106955DF4E40/standard.jpg

http://www.fototime.com/0C7D9DF5013036E/standard.jpg

http://www.fototime.com/E1E25BCBAF1E22B/standard.jpg

This is the finished product.

http://www.fototime.com/250463FFDF893F7/standard.jpg

http://www.fototime.com/CC9BDD9F8451FA3/standard.jpg

If the finished product goes all the way around I say you are finished. That will stop the water from getting into the center. Make sure you put a VB down.

The gutter runs the entire 24’ length of the retaining wall. How about water that sinks under the footing and appears in the crawlspace in front of the spread footing due to capillary action? That is why I was going to install a trench drain in front of the retaining wall spread footing. NOTE: The crawl space grade is 4 feet below the grade on the other side of the retaining wall.

If the finished product goes all the way around I say you are finished. That will stop the water from getting into the center. Make sure you put a VB down.