PORTLAND, Maine — Brendan Felix’s yellow metal detector chirped and warbled as he ran it over an exposed tree root in front of a house on Kenwood Street last week. Felix let out a sigh, reached for a long metallic probe and started poking it into the ground below the tenacious root, listening for a telltale metal-on-metal sound.
He was searching for one of the long-buried valves that controls the flow of drinking water throughout Greater Portland.
“I’ve got 20 minutes, max,” Felix said, setting himself a time limit before moving on.
The deadline was important, as there were still more than 42,000 water service valves to find.
The Portland Water District has a total of 64,000 valves it needs to find in order to bring its records up to date. To help complete the already decade-old project, it recently hired South Portland engineering firm Sebago Technics, which is using sophisticated GPS mapping techniques, as well as shovel-wielding, boots-on-the-ground workers.
With Sebago Technics on board, the District hopes to complete the project in fewer than two-and-a-half years.
The Portland Water District supplies water to 16 percent of Maine’s population, including the communities of Falmouth, Raymond, Scarborough, South Portland, Standish, Windham, Cape Elizabeth, Cumberland, Gorham, Portland and Westbrook. Until the mapping project started, all the service valve locations, for homes as well as businesses, were recorded on paper cards with hand-drawn diagrams.
“We’re a 150-year-old organization,” said Chris Crovo, the District’s director of asset management and planning, “and some of these valves have been in the ground that long.”
Crovo said it’s important to accurately find and geolocate the valves.
“We need to be able to find [valves] fast when a customer is in trouble, and they’ve got a broken pipe flooding their basement,” he said.
Funding for the project comes from $2 million in state and federal grants, as well as no-interest loans originally intended for finding and replacing lead pipes. But since no lead pipes were found, Crovo said the unused balance is being repurposed to find and record valve locations.
At Sebago Technics headquarters on John Roberts Road, engineers have developed an online digital dashboard for the massive job combining satellite maps, tied directly into the District’s servers, and a variety of numbers and graphs.
The maps show thousands of blue dots where valves are suspected to be. Field workers like Felix then head out to those locations to track them down and record precise GPS coordinates.
“With our GPS, we can get it down to under 3 inches easily,” said Sebago Technics Director of Survey Advancement Matthew Ek. “Most of them are within a centimeter.”
When field workers record positions in the field, the blue dot on the map automatically turns green and a counter ticks down the number of valves remaining. As of Friday afternoon, they had 42,626 to go.
If a valve can be located but trees or buildings prevent a good GPS signal, the dot turns purple. That means the geolocation will have to be plotted out later using old fashioned, terrestrial surveying equipment.
In the rare case that no valve is found at all, the blue dot turns red.
“Some are buried in lawns, or in driveways under cars. Some are in front walks,” Ek said.
“One was under a giant dumpster,” said Sebago Technics geospatial expert Jake Hansen. “We know it’s there; we just haven’t seen it yet.”
On Kenwood Street, Felix dug a hole where he thought the root-entangled valve must be. At first, nearing his time limit, he found nothing but a healthy-looking worm. Then, finally, he found the valve about a foot underground.
“There it is,” Felix said, jubilant. “It’s like a treasure hunt.”
A few minutes later, another blue dot on the dashboard screen turned green.
