prevention of horizontal soil water movements, esp. in tree pits

Hi all of you,

Maybe one of you has a better idea and/or can support by giving further details.

This is my base text to raise a TQ with our Client.

This will (might) be for future use

Regarding capillarity breaker to prevent capillary movement of saline soil water to penetrate into planting medium.

In general specifications, detailed drawings and BoQs consider a capillarity breaker by spreading an adequate layer of coarse gravel covered by one layer of geotextile. This method is sufficient in horizontal and even moderately sloped areas but it does not prevent penetration of saline soil water from verticals i.e. tree pits, deeper planting beds, and the like.

A feasible solution in breaking the capillarity and at the same time allowing sufficient drainage effect is by installing a composite of geotextile/drainage net/geotextile. This material is usually sturdy and stiff enough to allow a usage in the vertical. At the same time flexible enough to follow undulations in the landscape sub grading.

This sort of material is light weight, durable, easy to transport and store, and can be cut to fit, an ideal substitute to tedious drainage gravel transportation and spreading as well as insufficient geotextile overlapping due to heavy winds or consequent material installation.

Thanks

Ernst

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Permalink Reply by Ernst Glaeser on November 12, 2011 at 3:57am

Under Datasheet: D1 Data GB09 Dated 01.01.2010, Terram Salt Barrier

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Permalink Reply by Andrew Garulay, RLA on November 12, 2011 at 5:00am

Thanks.

Will you need to use it underneath as well? Is capillary movement upward in the soil profile going to be a problem?

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Permalink Reply by Ernst Glaeser on November 12, 2011 at 9:41pm

Please see my reply above: November 2, 2011 at 10:39pm

Reg.

Ernst

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Permalink Reply by Matthew Latham on November 10, 2011 at 1:48pm

Here's an idea. Surround the tree pit with a six-inch thickness of open graded gravel (ASTM D448 #57) wrapped in filter fabric, from just under the adjacent sidewalk to the bottom of the tree pit. Place a 4" dia. perforated PVC pipe wrapped in filter fabric at the bottom of the gravel and connect it to the storm drain system. This will collect the horizontally moving water and drain it away before it gets to the tree pit.