Streamline - Spring 2012 - (Page 11)
BY NANCY CARR, SOURCE WATER PROTECTION SPECIALIST
A FORMAL REPORT on groundwater in three regions in Virginia is forthcoming. The Department of Environmental Quality engaged three hydrogeologists for this extensive project. Their findings will help developers and water supply planners when decisions are made for withdrawal permits. Towns seeking new sources will find it useful.
The new data arrangement by Virginia’s hydrogeologists allows us to predict where to locate a future water source. And in western Virginia, springs should not be overlooked.
The three geologists and the areas they are studying currently include Todd Beach (the Coastal Plain) Brad White (the Blue Ridge) and Joel Maynard (the Shenandoah Valley.) The men are creating databases with information from site visits, pump tests, and well logs for public sources, private sources and test holes that the DEQ has drilled. The pump test done on a new well sets a limit on how many gallons per day can be withdrawn without overusing the aquifer. A criterion now for any new wells drilled by utilities is to submit the new well logs to the DEQ in Richmond. When a well is taken offline, DEQ considers it for use as a study well. Groundwater is the major source of potable water for most of Virginia’s counties. The project is creating a view of the groundwater available in particular areas. This knowledge is necessary, so that the supply in specific aquifers remains sustainable. The groundwater project is important to communities that seek to grow and need more available water. Groundwater aquifers may be confined or unconfined. Unconfined aquifers are recharged from the surface by infiltrating precipitation. Confined aquifers are more or less stuck with the amount of water stored in them by geological processes that may have taken place eons ago. They do not get recharged once their stored water is gone. Springs used for drinking water are less common now, as many have
been declared GWUDI – Ground Water Under Direct Influence. The GWUDI label applies more frequently to wells also, as surface water reaches an unconfined aquifer with contaminants that did not exist or were not sampled for in the past. A surprising finding in the Coastal Plain study is that the many small, usually private, well withdrawals, lower the water table more than previously believed. White explained that when he finishes his report on wells in the Blue Ridge, then he will start analyzing the Piedmont. He has accumulated information by using electronic databases from the Water Control Board, county statistics and the Department of Health. After culling out repetitions, he has data for about 50,000 wells. The information on existing wells in an area will illustrate the availability of groundwater in the Blue Ridge, the expected yield of a new well, and the sustainability of the supply. White reached his conclusions by studying not only 50,000 wells, but also by estimating watershed recharge. He created hydrographs that show that the fluctuation in groundwater levels correlates with stream flow and precipitation. Some wells are more seasonal than others in water level and storage, depending on where the fractures in the bedrock are and how they are oriented to the surface. The fluctuations tell a story about the storage capacity of the aquifers. The database will be available on the DEQ website and will be open to the public. With data for specific areas of the Blue Ridge, it will serve as a quick reference to what is possible for well drilling there and the general hydrogeologic processes.
Table of Contents for the Digital Edition of Streamline - Spring 2012
From the President
From the Executive Director
Where is Virginia’s Groundwater?
Basic Management Skills
Planning or Piecemeal?
CPEs and YOU
The Sludge Bag
Fracking Rapidly Becoming Unpopular
Amazing We All Learned English!
Springtime Safety – Outdoor Hazards
Spotlight on Western Virginia Water Authority’s Blue Ridge Brawler
VRWA’S 24th Annual Exposition Agenda
Throwing My Loop
Do You Know What Your VRWA Benefi ts Are?
Rural Water Review
Welcoming New Members
Board Of Directors
Index To Advertisers/Ad.Com
Streamline - Spring 2012