SUFFOLK, VA – HRSD will resume replenishment of the Potomac Aquifer with drinking water quality SWIFT Water as early as August 20. Recent groundwater sample readings taken on August 12 indicated less than half of the maximum contaminant limit (MCL) for nitrite. As reported on August 6, elevated nitrite levels were discovered in 11 of 15 SWIFT Water samples taken in June.
In an abundance of caution and in demonstration of HRSD’s ability to withdraw SWIFT Water from the aquifer, HRSD cleared the aquifer of the SWIFT Water with elevated nitrite levels until tests done on August 12 showed nitrite levels measuring below half the MCL. HRSD continues to remove the SWIFT Water from the aquifer for an additional seven days beyond that point. An estimated 4.8 million gallons of SWIFT Water exceeded the MCL. The total amount withdrawn is estimated at 20 million gallons.
SWIFT Water entering the aquifer travels slowly – initially moving at a rate of speed of approximately 50 feet over three days’ time and slowing significantly as the water moves further away from the recharge well. With the nearest drinking water well more than one mile (5,280 feet) away from the SWIFT Research Center replenishment well, the instability of nitrite in the groundwater environment, and the slow travel speed of SWIFT Water, at no time was there any risk of elevated nitrite groundwater reaching any drinking water well.
In addition, the tasting system at the SWIFT Research Center was not impacted by this issue. Free chlorine is added to SWIFT Water used for tasting in order to achieve the required drinking water chlorine residual. The addition of chlorine oxidizes the nitrite, eliminating it and ensuring that the SWIFT Water available for tasting meets drinking water requirements.
The SWIFT Research Center, located on the grounds of HRSD’s Nansemond Treatment Plant in Suffolk, VA, began operations on May 15 as a learning facility that will inform the development of future full-scale SWIFT facilities for aquifer replenishment.
HRSD’s mission is to protect public health and the waters of Hampton Roads by treating wastewater effectively. A political subdivision of the Commonwealth of Virginia, HRSD was created by public referendum in 1940 and currently serves 18 cities and counties in southeast Virginia - an area with a population of 1.7 million.
HRSD Vision: Future Generations will inherit clean waterways and be able to keep them clean.
Should you have any questions or comments, you may contact:
Leila Rice, APR - 757.460.7056
Director of Communications