De Flon explains that in the valley, there are approximately two to four feet of clay soil, then a layer of sugar sand. You want to get the water down into the sugar sand. From the surface, all you see of a French drain is the metal grate. Underneath is a more elaborate system. Wire screens cover the ends.
Small rocks are then placed on top of the culvert, then dirt is added toward the top.
In Marquez's neighborhood, as in many of the newer developments in the North Valley, there are no curbs or gutters. So the water has to be maintained in their own yards. Every subdivision has an approved hydrology plan that a civil engineering firm does, whether it's county, city or village of Los Ranchos, according to Jim Forrester, co-owner with De Flon of Hilltop. Frainich says a French drain is only good for about five or six years. They'll silt, or grass clippings keep falling through the grate and build up.