Identifying sustainable groundwater supplies more important than ever
By Kenneth Bannister
Access to a stable and clean water supply is one of the foundations of our society. Water is used to support populations, facilitate business, generate power, and irrigate crops. Despite its importance, water is becoming increasingly scarce. According to a May 2014 report from the United States Government Accountability Office, water managers in 40 states expect water shortages in some portion of their states in the next decade.
As population growth continues and weather conditions change, municipalities must prioritize identifying large and sustainable water supplies. This imperative applies to cities and counties across the country, not just those in arid climates.
When a municipality determines that it needs additional water resources, two options are most commonly available: groundwater or surface water. Surface water sources — such as lakes, rivers, and reservoirs — can hold significant amounts of water, but are often cost prohibitive for smaller systems due to the costs of constructing and operating treatment plants which are required to deliver potable water. Surface water treatment plants can cost hundreds of thousands or even millions of dollars.
Groundwater supplies are often a preferred choice for cities and counties. Whether looking for 40, 400, or 4,000 gallons per minute, groundwater supplies can often meet a variety of needs and have the added bonus of requiring little to no treatment. In fact, a recent groundwater sourced developed in Berkeley County, West Virginia produced several thousand gallons per minute of clean water.
Identifying groundwater supplies is critical because they have major economic implications for municipalities. That water can be used to attract manufacturing facilities, support new housing developments and multifamily projects, and ensure clean drinking water as municipalities grow. Groundwater is used for geothermal heating and cooling of municipal buildings and in the production of geothermal power. It can provide cooling for power plants as well.
So how does one find large groundwater supplies?
The search can be divided into four steps. First, a locality needs to determine its water needs. This planning process should take long-term economic development goals into consideration. Don’t just think about the next few years when considering water demand; instead, project long-term needs. Thorough planning is a key step that shouldn’t be overlooked.
Second, establish a study area to search for water supplies based on the economics of bringing that water to the distribution system, and considering areas of potential growth of the community. Third, using geological maps, topographic maps, and remote sensing with aerial or stereoscopic photography, groundwater favorability areas are identified. Collaborating with water supply experts, municipalities should then narrow these areas to the most promising and logistically favorable based on your long-term planning. Finally, it’s time for detailed field work to explore these favorability areas.
Finding water supplies is both an art and science. Fortunately, the science has improved in recent years as technology has evolved to enhance the likelihood of finding and utilizing groundwater supplies. Geophysical surveys utilizing technologies such as electrical resistivity, magnetometry, refraction seismology, and other methods can provide an image of what’s below the ground surface. Interpretation of that imagery, in conjunction with remote sensing and map work, enables an experienced geologist to identify possible viable groundwater sources.
Following successful identification and development of a new groundwater source, responsible municipalities will test groundwater supplies by pump testing to measure the yield and predict how the supply will fare over its lifetime and to determine the source of recharge to the well to ensure that the water doesn’t come from a contaminated area, a key safety concern.
Identifying a safe and reliable water supply is more important than ever. As water demands increase, new tools allow for more efficient and effective groundwater searches. Ultimately, finding that sustainable groundwater supply will create a lasting, positive impact on local communities for generations.
Kenneth Bannister, C.P.G is the Environmental Team Leader at Draper Aden Associates, an engineering, surveying, and environmental services firm based in Virginia. A hydrogeologist, he has over 35 years of experience and has worked on hundreds of water supply projects with a 90 percent success rate. He can be contacted at [email protected].