WLS-017 Landscape Guidelines for Non-Standard Septic Systems

Version: 06/19/2023

Landscaping guidelines for nonstandard septic systems.

Vegetative cover is intended to prevent erosion of the soil over non-standard 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 on the top of the mound while the application of effluent produces wetter than ordinary soils immediately below. Since non-standard 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 non-standard septic system shall be drought resistant and have non-invasive root systems to prevent damage and/or failure of the septic system. Attached is a suggested list of various plants suitable for planting directly on your non-standard septic system. This is only a partial list, and you may want to consult a landscape professional for other plant selections. This professional should be advised of the non-standard 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 non-standard 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 Non-standard Sewage Disposal Systems