Question
Jim,

    The output of our washing machine is out on a hill that slopes off into grass.  We just replaced the entire line from its connection (corrugated plastic pipe), and there is no other place to put it.  We have tried putting rocks right where it comes out, but the force when it drains is pretty strong.

    What alternatives would you suggest to keep the hill and down lower washing out?

                      Thanks, Alan


Answer
Hi Alan,

About Grey-Water Effluent Erosion:

You could construct what amounts to an 'end-of-the-line' grey-water receptacle unit that would collect most of the effluent as it exits the end of the pipe to hold it temporarily until it can drain-away.  This could just be a large plastic trash-can sunk into the ground to collect the grey-water.  Make some drainage holes in the bottom of it and place a layer of gravel in the bottom.

A farm supply store will sell larger plastic tanks used for livestock watering if the 30-55 gallon average plastic trash receptacle is not large enough for your effluent volume demands.

Depending upon the physics of the surrounding soil, this tank system should have enough holes in it to drain into the ground between fill-ups (laundry-washings or etc.).   This is a variety of a cistern construction. This could be designed to be out-of sight; it may need periodic servicing and should be well covered to prevent debris falling into the receptacle.

A modification of this system may incorporate a submersible pump to periodically use the tank ed grey-water to water surrounding lawn and gardens as the tank is emptied for this purpose; some systems deploy two recptacles, one with holes to drain with immediate fill (primary) and another to collect and hold for later use (secondary cistern). Depending upon various factors, the secondary tank will be variously empty or full as a water resource for the property.

Alternatively, you might try planting erosion preventing grasses and plants near the effluent source.  Such plants as liriope ('monkey-grass'), Morpa or Ermelo Lovegrass (Eragrostis species), Day-lilies, Ivies, Sedums,...etc., whatever can grow in your area and serve to prevent erosion.
In some cases, a stand of inexpensive Fescue turf grass might do the trick; the seed is widely available.

You can also 'terra-scape' the hill.  This means you make the hill more step-like by using retaining walls and structures.  This can be a rather expensive and labor intensive project however, but it would, in theory , replace the slope with level stretches which you can manage by landscaping them as lawn or gardens.

Some grasses and plants will not do well with a grey-water source that is high in phosphates and other chemicals found in commercial detergents.  You can find more environmentally friendly detergents to use in your system that will bio-degrade and pose no threat to the soil ecosystem.

Note: Some communities have building code laws concerning grey-water effluent systems, so check into this to avoid breaking any laws.

Good Luck!
__ Jim G.