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WLS-017 Landscape Guidelines for Non-Standard Septic Systems

Revised 03/06/2007

bulbVegetative cover is intended to prevent erosion of the soil over nonstandard septic systems such as mound, at-grade and pressure distribution systems. It also assists with a natural means of evapotranspiration of the sewage effluent from the system. These types of septic systems create a special set of conditions due to the way they function. The placement of the gravel bed creates a drought area directly above on the top of the mound while the application of effluent produces wetter than ordinary soils immediately below. Since nonstandard septic systems tend to be relatively dry on top, they are most conducive to planting native grasses, herbaceous plants, various bulbs, succulents, herbs and other ornamental ground covers that are drought resistant or drought tolerant.

All plants covering a nonstandard septic system shall be drought resistant and have non-invasive root systems o prevent damage and/or failure of the septic system. Attached is a suggested list of various plants suitable for planting directly on your nonstandard septic system. This is only a partial list and you may want to consult a landscape professional for other plant selections who should be advised of the nonstandard septic system.

  • Vegetation management is essential to proper maintenance and monitoring of these types of systems.
  • Do not plant trees or large shrubs directly on a mound or at-grade system or within the area of any nonstandard leach field.
  • Do not plant a lawn that requires heavy watering, such as bluegrass. It is best to plant drought tolerant grasses such as various types of fescues.
  • Do not plant ivy or ice plant as they retain moisture thereby restricting evapotranspiration which will keep the system too wet. Ivy and ice plant both have very invasive root systems and are prohibited on any type of septic system.
  • Do not use overhead “Rainbird” type sprinklers. The irrigation method of choice is drip irrigation which will minimally provide enough irrigation for the plants while keeping the system as dry as possible.
  • Do not promote activities on the system that will add to soil compaction and loss of absorption capacity.
  • Do not drive across the system.
  • Do not cut or mow vegetation when the soil is wet. Remove clippings promptly.
  • Do not allow large animals on the system area.
  • Do not cover valve boxes and performance wells.
  • Do not operate equipment on system when soil is wet.

Please Note: Heavy equipment or vehicles driven over the system may damage it.

Suggested Plant List for Nonstandard Sewage Disposal Systems

Color Key: B = Blue, O = Orange, P = Pink, Pur.= Purple, R = Red, W = White, Y = Yellow

Herbaceous Plants

Common Name Scientific Name ColorHeight Comments
YarrowAchillea speciesY,W,R12 inchesfire retardant
Cape WeedArctotheca calendulaY6 inchesspreads
Silver MoundArtemesia schmidtianaY2 feet
Bachelor's ButtonsCentaurea cyanusB,P,R,W1-2 feet
CosmosCosmos bipinnatusR,Y3-6 feeteasy
Yellow CosmosCosmos sulphureusY3-4 feeteasy
Monkey FlowerDiplacus speciesmany1-3 feet
Fortnight LilyDietes iridiodesW4 feettough
FleabaneErigeron karvinskianusW,P1-2 feetdrought tolerant
California PoppyEschscholzia californicaO,R1-2 feetspreads
Blue FescueFestuca ovina glaucaB12 inchesspreads
DayliliesHemerocallis speciesmany1-6 feeteasy
Trailing LantanaLantana montevidensisR1-2 feetspreads
Sweet AlyssumLobularia maritimaW6-12 inchesspreads
Forget-Me-NotMyosotis sylvaticaB6-12 inchestough
Mexican Evening PrimroseOenothera speciesR,W,Y1-2 feetprofuse
SantolinaSantolina speciesY,W1-3 feetaromatic
Lamb's EarsStachys byzantiaPUR12 inchesspreads
NasturtiumTropaeolum majusO,R,Y,W12 inchesspreads
VerbenaVerbena speciesvaries1-3 feet
California FuchsiaZauschneria californicaR1-2 feetdrought tolerant

Bulbs

Common Name Scientific Name ColorHeight Comments
Naked LadyAmaryllis belladonaP3 feethardy
MontbretiaCrocosmia crocosmiifloraR2 feethardy
IrisIris speciesmany1-2 feetdrainage
DaffodilNarcissus speciesY,W1-2 feetreproduces
TulipTulipa speciesmany1-2 feettough

Succulents & Herbs

Many to choose from; very drought tolerant

Woody Ground Covers

Common Name Scientific Name ColorHeight Comments
Ground Cover ManzanitaArctostaphylos uva-ursiW1-2 feetto 15 feet
Dwarf chaparral broomBaccharis pilularisW1-2 feettough
various prostrate formsCeanothus speciesB1-2 feetspreads
various prostrate formsCotoneaster speciesR6-12 inchestough
various prostrate formsJuniperus speciesY1-2 feetspreads
Prostrate RosemaryRosemarinum officinalisB1-2 feettough

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Santa Rosa, CA 95403
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