Hi, my wife and I have been dedicating one main improvement project per year for our backyard for the past couple years. The most recent is having a new retaining wall and slab built in my back yard. It's about 8' wide x 40' long. The wall will be 4.5' high.

I live in a typical track home here in SoCal and a corner lot at that. What we're doing is creating additional deck/patio space for chairs and what-not to the back side of our pool. When the lot was built no drainage to the street was established, so it's too late and way too costly to consider that with all the concrete to go under and neighbors yards to go through, so forget that. What I need to come up with is a way for the winter rains to drain off rather than collecting and being trapped on the new slab. If there's no drainage the the new area could fill very quickly.

I'm simply looking for a non ultra expensive way for drainage in back of the wall and the slab. The soil here is very sandy and rocky, so great for drainage. I've never experienced a problem with drainage on my property anywhere.

Here's what I found on local rainfall:

[I]"The annual average precipitation at Rancho Cucamonga is 14.77 Inches. Rainfall in is fairly evenly distributed throughout the year. The wettest month of the year is January with an average rainfall of 3.50 Inches."[/I]

[I]"Rainfall in the City averages four inches of rain per year. However the term "average rainfall" is misleading because over the recorded history of rainfall in the City of Rancho Cucamonga rainfall amounts have ranged from almost no rain at all in some years to 26 inches in very wet years."[/I]

Will a channel grate work on the slab?

Can it drain straight down and into say aggregate?

Will horizontal perforated pipe dropping into aggregate work in back of the wall?

How deep should the aggregate work in both cases?

Since the pool is about 8-9 feet away and the great soil we have should I have to worry about any sub corrosion around the shell of the gunite pool?

Other ideas? Thoughts?

Thanks for any help.

Tony

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