A Leaking Sewer Pipe & Soil Erosion

Soil Erosion

• Soil is a life-giving mixture of organic and inorganic material, built over vast intervals of time. Partly derived from weathered bedrock and sediment deposits, partly from the decay of organic matter and the activities of fossorial (or burrowing) organisms, it mantles much of the planet’s terrestrial expanse. The erosion of soil is certainly a natural process – as in a stream’s excavation of its channel – but where excessive it can strip essential nutrients from a landscape, destroy vegetation communities and threaten human structures.

Effects of Leaks

• A leak from a sewer pipe may saturate soil, making it more vulnerable to subsidence or to landslide. Great planes of soil can literally slide away if waterlogged or undercut by inundation, a situation certainly made more probable by an incline, as on the slopes of a ravine. Additionally, deeply wet soil is more vulnerable to compaction – by feet, hooves, vehicles or other aboveground forces – and the resulting gullies may collect runoff and hasten more extensive erosion.

Symptoms

• In some cases, soil erosion itself announces a compromise to a sewer line in dramatic fashion, as when sinkhole-like depressions may suddenly form. A long buildup to such an extreme situation can be revealed by subtle symptoms like an unexpected proliferation of grass or other vegetation over the underground leak. Early stages of erosion can actually worsen the leak situation by undermining a pipe’s support as surrounding soils are washed out in the escaping flow.

Mitigation

• Aside from repairs to the pipe and the obvious mitigation efforts directed toward water and soil contamination, the erosion itself should be accounted for. A common approach is to plant soil-anchoring vegetation appropriate to the area’s ecology and the immediate topography and microclimate. Grasses are often fast-growing and fast-spreading, infiltrating soil with underground runners called rhizomes (depending on the type of grass). They therefore are frequently good choices to quickly address an erosion issue. Further planting of groundcover herbs and shrubs, as well as trees where applicable, can more thoroughly secure soil and also help to rebuild its nutrient profile.