Solutions to Groundwater Hydraulic Control Concerns

By Tomas Will, Sr. Environmental Scientist

Horizontal well technology is often chosen to manage groundwater movement instead of traditional vertical wells because it offers the following advantages:

1. Provides significantly increased radius of influence and greater control over pore pressures allowing for a small number of horizontal wells to exceed the performance of dozens of vertical wells.
2. Allows targeting of subsurface areas that may not be easily accessible from the surface.
3. Does not interrupt or disturb commercial activities, facility operations, or sensitive habitats at the surface and does not involve intrusive drilling activity that damages existing structures at the surface.
4. Simplifies system operation and long-term O&M. Horizontal well systems are typically more cost effective than vertical wells over the lifetime of system operation.
5. Achieve performance targets in a shorter amount of time.

The three most common applications of horizontal wells to manage groundwater movement are discussed below:

I. Contaminant Migration

By controlling the movement of groundwater, subsurface contamination can be more easily managed. Groundwater gradients can be manipulated to contain and even shrink contaminant plumes. Typical uses of horizontal well hydraulic control for contaminant migration include:

• Preventing a groundwater contaminant plume from migrating towards sensitive areas.
• Restricting the migration of a groundwater contaminant plume out of or into an adjacent property.
• Reducing the dispersal of a groundwater contaminant plume so that is causes the contaminated groundwater area to shrink and concentrate in a desired location where it can be easier to treat and/or monitor.

II. Dewatering

Using dewatering techniques to lower a groundwater table or drain soils can be a complicated engineering process that involves multiple variables.  The increased control provided by horizontal wells allows for more reliable results. Typical uses of horizontal well hydraulic control for dewatering include:

• Localized lowering of groundwater table elevation to facilitate excavating activities associated with construction, utility installation, or soil remediation.
• Removal of groundwater from abandoned mines or other large subsurface structures.
• Preventing seepage of groundwater up through a building slab foundation due to a shallow groundwater table.

III. Redirecting Groundwater

For decades, natural resource managers have relied on taking groundwater from an abundant area to a target area. Groundwater has the benefit of natural filtration which means that it will be pumped to the surface free of many of the impurities present in surface water. Typical uses of horizontal well hydraulic control for redirecting groundwater include:

• Diverting groundwater from beneath an existing surface water feature to a different surface water feature for natural resource management associated with fish hatcheries, wetlands, sensitive habitats, etc.
• Restoring a depleted aquifer.

When one of your clients calls with questions about managing groundwater, how will you start the process to effectively identify and evaluate your best options?  Call our horizontal remediation well experts at 1-877-788-4479 to discuss your current project needs.