underdrains

To reduce these potential problems it requires a significant amount of subbase, detention, and underdrains to make sure the water is drained as fast as it infiltrates (and it infiltrates really, really quickly).

Holey Concrete: Pervious Paving Reduces Stormwater Run-off | Inhabitat 2009

The commonly used diameters of underdrains are between 5 and 8 cm.

2.1. Open ditches 1982

Drainage trenches intended for laying of underdrains vary in width between 0.30 and 0.70 m at ground level and 0.06 and 0.20 m at the base.

1.1. Survey of local conditions and site reconnaissance 1982

Channel networks are usually installed on pasture land or when the agricultural value of the land does not justify the installation of underdrains.

2.1. Open ditches 1982

Both these factors no doubt assist the free course of water in exerting pressure on the finished invert after the underdrains have been closed up on completion of the work.

Pressure, Resistance, and Stability of Earth American Society of Civil Engineers: Transactions, Paper No. 1174, Volume LXX, December 1910 J. C. Meem

Lord Kames, writing before the time of draining-tile, dislikes open ditches, by reason of their interference with tillage, and does not trust the durability of brush or stone underdrains.

The Atlantic Monthly, Volume 13, No. 79, May, 1864 Various

We are going to take the 50 percent, glad to get half way upon this question, and submit it again to a still further change, and that change is to throw the effluent upon the surface of a filter bed, so that it can be filtered and drained by properly constructed underdrains and there will not be a vestige of polluted matter left to run into the Lake.

City of Toronto Disposal of Sewage and Water Filtration 1907

-- Doubtless there are places and times when stone, or boards, or brush should be used in construction of underdrains, but they are relatively few in number.

Crops and Methods for Soil Improvement Alva Agee 1900

The prompt removal of excessive moisture by drains, and preferably by underdrains, is essential to profitable farming in the case of most wet lands.

Crops and Methods for Soil Improvement Alva Agee 1900

Such underdrains lack permanency, as a rule, though some stone drains are effective for

Crops and Methods for Soil Improvement Alva Agee 1900