It may have looked odd to motorists driving south on Route 97 in Cooksville, the huge mechanized shovel scraping away clay inches at a time in front of a man squinting at an upright ruler.
But inches are critical when it comes to creating wetlands, as State Highway Administration workers from the Dayton maintenance shop are learning.
About eight people from the Dayton facility hope to be the first SHA workers in the state to create a wetland to replace one damaged by a highway project.
"We go out and cut trees down and build roads and everybody's saying, 'Well, boo you,' " said Charlie Watkins, the resident maintenance engineer who supervises the Dayton shop. "Now we're actually giving something back."
In the little more than 10 years that the SHA has been "mitigating" wetlands damaged by highway projects, the work has been done by private contractors. SHA mitigation projects have ranged from 5 to 15 acres and cost roughly between $30 and $50 an acre to create, said Bill Branch, mitigation manager for SHA's Environmental Programs Division.
Letting the Dayton workers do their own work may give them the experience to do similar, small-scale jobs as highway projects require them, Mr. Watkins said.
Using SHA employees, at a cost of about $18,000, also saves money. The project was estimated to cost about $30,000 if done by contractors.
The Cooksville project, just south and west of the interchange of Route 97 and Interstate 70, will create two-thirds of an acre of wetlands to replace part of those that were damaged in 1991 by bridge construction where Route 94 crosses the Patuxent River.
Federal wetlands regulations required that the SHA had to replace twice the six-tenths of an acre that it disturbed. Half of the mitigation was done at the bridge site in 1991; the other half is being done in Cooksville.
To convert the grassy roadside into a wetland, the SHA workers have to lower the land about 3 feet in some places, less in others. The grading will lower the land enough so that water flows into it and saturates it, Mr. Branch said.
Once this week's grading is completed, SHA workers will scatter a mix of "non-aggressive" grasses. The grasses, which include bluegrass, red top and Japanese millet, will grow quickly, prevent erosion, and yield to wetland plants whose seeds arrive with bird droppings, Mr. Branch said. Seeds for cattails, which are commonly associated with wetlands, will be wind-borne to the site.
Workers will then add wetland trees such as red maple, green ash and sycamore, and shrubs such as elderberry, winterberry and silky and red ozier dogwoods.
"They're very colorful, and they produce berries that are very attractive to wildlife and to birds," Mr. Branch said.
Part of the area will be graded so that it usually has between 6 and 12 inches of water, making a nice home for ducks, frogs, salamanders and turtles.
An area slightly higher in elevation will provide a soggy medium for plants that are used to growing in a waterlogged, oxygen-starved environment, Mr. Branch explained.
So in a few months, Mr. Branch said he hopes motorists will notice new kinds of wildlife in the marshy little pocket of land next to the I-70 off-ramp.