Irrigation Drainage Solutions

Methods

• 1

  Move excess water from specific problem areas such as planter beds, hardscaped areas, window wells and low-lying lawns by installing catch basins capped by grates. Install a cement or plastic catch basin flush with the ground surface that goes down to the depth of the buried PVC or corrugated pipe that carries the water away. Cap the basin with a round grate in turf areas, a square grate in hardscaped areas, or an atrium (domed) grate in areas where landscape features such as mulch or debris might cover and clog flat grates. Suit the size of the catch basin to the volume of water anticipated, making allowances for unusually large accumulations that may occasionally occur. Maintain catch basins regularly to prevent blockages.

• 2

  Install a channel, or trench, drain to collect and drain water from paved areas or to remove seepage from slopes to reduce erosion. Dig a long trench, 4 inches wide and deep, and place interlocking sections of trench drain into the channel. Top the drain with its grate.

• 3

  Collect and transport excess water from poorly drained areas or water flowing across a slope with a French drain. Dig a trench and line it with landscape fabric. Install a 4-inch or 6-inch perforated, corrugated pipe in the trench. Backfill the trench with gravel. Layer landscape fabric over the gravel to prevent soil from sifting into it. Cover the fabric with soil.

• 4

  Pile soil into long low mounds, 2 to 6 inches high, called berms. Berms slow runoff from slopes and direct it away from low-lying areas or buildings, giving water a chance to penetrate the soil rather than collect as standing water. Plant berms with vegetation to prevent their erosion.

• 5

  Excavate a shallow, gently sloping ditch called a swale, or biofilter, to capture and slowly transport runoff. Plant the swale with grass to promote soil infiltration. Swales can be an inexpensive alternative to underground drainage, especially if there is a naturally low-lying area that lends itself to such use. Design a swale so that it does not hold standing water, which can encourage mosquitoes.

• 6

  Install permeable pavers, which allow water to pass through them. Use concrete block pavers for driveways or pedestrian areas. Prepare a soil subgrade. Add a gravel base and a bedding of sand. Then set the pavers. Fill voids around the pavers with gravel or soil and grass. Use plastic pavers on areas of uneven terrain and in areas where not as much weight needs to be supported.

• 7

  Amend the soil to improve drainage. Till and add organic matter to large-pored, coarse-textured, sandy soil to reduce leaching and increase its ability to absorb and hold water. Organic matter applied to small-pored, fine-textured, clayey soil helps create larger pore spaces that allow water to penetrate. Organic matter also encourages earthworms and other organisms that help loosen soil.

• 8

  Aerate lawns routinely, especially those planted in fine-textured soil, to break up layers of thatch and allow more water infiltration. Plugs should be 2 inches apart. Fill in random low spots. Combine this with more frequent but shorter cycles of irrigation.

• 9

  Plant slopes with perennial ground covers or grass. Lawns and natural grassland are the most effective ground covers for slowing runoff. Terrace steeper slopes.

• 10

  Install drainpipe inside and outside the footing of a house to carry excess water away from the foundation. Lay a 4-inch to 6-inch bed of gravel beneath the basement floor that slopes towards the drainpipe. Cover the gravel layer with a vapor retarder such as polyethylene film. Shape the land around a house so that it slopes away from the foundation at a slope of 1 inch per foot. Regrade after the first year to make up for soil settling. Grade the rest of the lot to a minimum grade of 1 foot per 100 feet.