I lead a group of volunteers who build new and maintain existing walking trails on a small mountain range in central New Hampshire. We have to drill into solid granite and chip away at it to create steps and other trail features. What are my options to do this in the field, where there’s no commercial electricity? Please don’t tell me we have to do it the way the laborers did it for blasting the old railroad tunnels.

— Hal G., Sanbornton, N.H.

Back when I entered the construction industry, if you wanted to use a power drill or saw, you had to have 120 volts of electricity. Period. You could plug into a commercial power source, or you could start up a heavy, bulky portable generator.

New technology has led to major advancements in both power tools and generators. You can now carry in a backpack an 18-volt cordless hammer drill that will easily bore holes up to 7 / 8-inch in diameter into solid granite. I’ve done it myself, and I know the tool works. That same cordless hammer drill, with the flip of a switch, can be transformed into a chipping hammer that will allow you to shape rock on the trail.

These hand-held hammer drills are much smaller than the large pneumatic hammers you see workers use to break up concrete slabs, but they’ll get the job done eventually.

The new cordless electric tools have seen major improvements in the motors. Many brands offer brushless motors that are more reliable. The Milwaukee cordless hammer drill that I’ve used offers longer life, 40 percent more run time and a hammer mechanism within the tool that is 35 percent harder-hitting. Those features will help you drill more holes faster.

I’ve been impressed over the past few years by the enhancements to the battery power packs that cordless tools employ. Lithium-ion is now the industry standard, and tool engineers are constantly improving efficiency by installing miniature computers in the tools to maximize the available energy. These small computers also protect the motors and battery from damage if the operator tries to overwork the tool. It’s fascinating technology.

In addition to Milwaukee, other manufacturers offer tools with lithium-ion batteries and onboard microcomputers. Your hardest task, in my opinion, will be selecting which tool to buy. Keep in mind that price is almost always the most accurate indicator of quality. The best tools often cost more because they contain the best parts and are the best engineered.

The biggest problem you’ll have with the cordless tools is the depletion of the energy from the batteries. You can buy extra batteries, but even that might not be enough to provide you with power for the entire day if you’re drilling and chipping rock for hours on end.

In that case, you might want to invest in a traditional corded power tool that operates on 120 volts of alternating current. You can then buy a very small and quiet electric generator that can be carried on a strong volunteer’s back to the job site on the mountain. Some of these generators weigh less than 50 pounds.

A small, quiet gasoline-powered generator can run all day on just one gallon of gas. It will produce 2,000 watts of electricity. That is plenty of power for one of the larger corded hammer drills or rock-chipping hammers.

My guess is that you want happy volunteers who get work done quickly, efficiently and with as little effort as possible. Buy the best tools, and you’ll achieve that goal. Thanks for all you do to provide great walking trails for us.

Tim Carter is a columnist for Tribune Media Services. He can be contacted through his Web site at www.askthebuilder.com.