Delaware Geological Survey senior scientist Scott Andres prodded a lump of coarse wet sand newly yanked from 70 feet below ground in Smyrna on Thursday, in the shadow of a drilling rig he hoped would open a window on the earth deep below.

The drippy sand, laced with tiny pebbles, was the first yield in an effort to drill and retrieve from underfoot a chain of round cores some 750 to 800 feet long, keeping intact the order of sediments and materials needed to prepare the second of two new research and monitoring wells for northern Kent County and southern New Castle County.

Andres’ work is at the leading edge of a joint study examining groundwater quantity and quality in the area, work supported by a $600,000 state appropriation last year. The state’s Water Supply Coordinating Council, U.S. Geological Survey, University of Delaware and Rutgers University also are participating.

“We’re putting in the wells and monitoring systems that will be used for the next several decades, in anticipation of the growth that will occur below the canal and north of Dover,” Andres said. “We want to have actual physical samples of the material that makes up the aquifers” and layers in between.

It is a crucial information gap for a part of Delaware almost entirely dependent on groundwater and wells for public and private supplies. State records show that 75 percent of the state’s 1,121 public water wells are 235 feet deep or less, with only 30 at 500 feet or deeper. More than half are only 135 feet deep. Delaware also shares aquifers with South Jersey, Andres said.

More needs to be known about the deeper aquifers that could be important to future needs, Andres said. Scientists and planners also need better well monitoring networks to identify natural and human-caused pollution and track the effect of droughts and well-pumping on water flowing through fragile aquifers created hundreds of thousands or millions of years ago.

“We would want to have that before the aquifers are heavily utilized, and those same aquifers already are heavily utilized in Eastern Shore Maryland and the Baltimore area,” Andres said.

Even today, aquifer maps are less than precise. Andres said workers were surprised to find that one water-bearing layer was missing entirely from cores taken in the Woodland Beach area.

The project, which will take about two years, calls for eight new wells, including Smyrna, the Woodland Beach, Middletown and Townsend areas, two sites in Blackbird State Forest, Cedar Swamp and a location near Odessa National Country Club.

Contact Jeff Montgomery at 678-4277 or jmontgomery@delawareonline.com.