Groundwater Monitoring Program Loudoun Water Community Water Systems

Challenge

Emery & Garrett Groundwater Investigations (EGGI), a division of GZA, was asked to obtain the data necessary to effectively protect and manage Loudoun Water’s vital groundwater supplies that serve their community water systems. This was to include designing, developing, and implementing a Groundwater Monitoring Program at the following Community Water Systems: Beacon Hill, Creighton Farms, Elysian Heights, Raspberry Falls, Rokeby, and Selma Estates located in Loudoun County, Virginia.

Solution

Effective groundwater monitoring programs serve to protect the quality and quantity of groundwater resources to ensure that sustainable groundwater supplies can be maintained for future generations. The benefits of implementing a groundwater monitoring program are many and varied. These benefits include, but are not limited to, the following:

• Provides an assessment of the changes that occur in groundwater storage in the bedrock aquifer and addresses whether long-term over-drafting (mining) of groundwater resources is occurring as a result of continued groundwater withdrawals.
• Provides for the long-term determination of actual groundwater recharge rates that occur during both significant rainfall periods and drought periods.
• Provides insights into the impact that rainfall events have on groundwater levels and groundwater quality. • Provides an understanding of the impact that the lack of rainfall (drought) has on water quality.
• Allows for an evaluation of the impact that drought has on groundwater levels and long-term groundwater resource availability and will help to provide the data necessary to develop a drought management plan.
• Provides an assessment of changes in groundwater quality and quantity associated with changes in land use.
• Provides an early warning system for the migration of groundwater contaminants that might be moving toward public supply wells.
• Allows for an evaluation of long-term changes in Production Well capacity and pumping efficiency so that the Loudoun Water can properly manage, re-develop, and protect the costly infrastructure investment that has been incurred to develop groundwater supplies for the Community Water systems.

Benefit

For each community system monitored to date, it has been demonstrated that the wells are not depleting the bedrock aquifer capacity and that sufficient recharge is available to support the groundwater withdrawals. This monitoring program is necessary to determine if this remains the case under all climatologic conditions associated with climate fluctuations and climate change.