Hydroconsolidation of soils is an all too common problem in southern California.
Hydroconsolidation
According to the Association of Environmental & Engineering Geologists (AEG) expansive and collapsible soils are frequent and costly geologic hazards. Hydroconsolidation is commonly referred to as soil collapse. Typically, it occurs when loose, dry, sandy soils become saturated and settle.
Geology and climate play a major role. Collapsible soils are extensive in arid climates, where wind and temperature have the greatest impact. Thus, it is prevalent throughout Southern California, and especially common in the High Desert region of California known as the Antelope Valley.
Sandy Soils in the Antelope Valley
In the Antelope Valley of California, 40-mph winds along with temperatures as high as 112 degrees create rather arid conditions. This keeps the sandy soils very dry. As a result, when a large amount of excess water inundates the soil, hydroconsolidation often occurs. Whether from a waterline break or leaky irrigation lines, this rapid form of settlement often happens. It causes a variety of problems for construction. Some examples of these problems include foundation movement which can be seen by cracks in the walls, as well as depressed landscape areas and voids under sidewalks.
Example 1 – Elementary School Retaining Wall Repair Project
Recently, Earth Systems performed a forensic geotechnical investigation determining the source of water damage at an elementary school. We also provided recommendations for retaining wall repair. Our engineers reviewed videotape footage of a large storm drain line present beneath the playground to find any leaks causing damage to the retaining wall. We drilled several borings and reviewed old plan-sets. Our staff encountered high concentrations of water at depths consistent with the most visible wall damage, evident by cracking and efflorescent visible on the outer surface. Ultimately, the solution included removing the existing soil behind the back of the wall, replacing it with proper backfill for drainage. Also, drilling cores through the bottom of the wall relieved any water build up in the future.
Example 2 – Elementary School Parking Lot Pavement Repair & Drainage
General Grading/Over-Excavation
Additionally, Earth Systems investigated distressed pavement at another local elementary school. The process included drilling several shallow borings. Also, we ran various geotechnical laboratory tests to determine the properties of the soil below the distressed pavement. We encountered shallow bedrock, along with trapped water between the bedrock and the existing pavement. The solution included a subsurface drainage system with edge drains and French drains for the site. In addition, Earth Systems provided over-excavation and remedial grading recommendations for both the existing parking lot and new pavement sections.
For further information on Hydroconsolidation of Soils in the Antelope Valley, please contact the Earth Systems Palmdale office.
