Introducing the Hampton Roads Seismic Network: Minimizing the Risk of Injection-Induced Seismicity in Virginia

Groundwater over-extraction from the Potomac Aquifer in southeast Virginia has led to a number of deleterious effects, including saltwater intrusion, falling groundwater levels, and land subsidence. To mitigate these effects, Hampton Roads Sanitation District (HRSD) is developing the Sustainable Water Initiative for Tomorrow (SWIFT) program. SWIFT is an innovative aquifer recharge program designed to enhance long-term groundwater sustainability while mitigating land subsidence and salt water intrusion within the Virginia Coastal Plain. SWIFT will replenish the Virginia Potomac Aquifer by recharging highly treated wastewater at a rate of up to 379,000 cubic meters per day (100 million gallons per day) by year 2032. To achieve this target, the SWIFT program comprises a network of up to five advanced water treatment and aquifer recharge sites throughout southeast Virginia. While there are numerous economic and societal benefits of the SWIFT program, there may also be the potential for fluid injections to cause unintended seismic activity. To begin understanding the potential for injection-induced seismicity, the Hampton Roads Seismic Network (HRSN) was installed in December 2021. The HRSN comprises five autonomous seismic monitoring stations. The primary objectives for HRSN are to (i) record the baseline rate of natural seismicity (if any) prior to full-scale aquifer recharge operations and (ii) detect seismicity that may be induced by fluid injections when full-scale aquifer recharge operations commence in 2026. This paper presents the rationale for HRSN, along with its spatial configuration, hardware specifications, autonomous capabilities, results from preliminary testing, and plans for long-term operations as the SWIFT program comes online.