Standing on Davenport’s Howell Street, just north of Rockingham Road, archaeologist Brennan Dolan reached into a plastic case and pulled out a resealable bag. Inside was a clam shell with three holes punched out for buttons.

The artifact from the late 1800s or early 1900s was the most interesting thing Dolan found this week as he and a fellow archaeologist performed “shovel tests” along the route of Davenport’s west side sewer diversion tunnel project.

Employed by a Marion, Iowa, consulting firm, the two were in Davenport to check for evidence of prehistoric American Indian habitation or early European settlement in areas along the route. Such investigations are required for projects receiving federal funds, said Tom Leabhart, project engineer for the city.

Given the location of this phase of work — from the railroad tracks south of River Drive to the base of the bluff at Fejervary Park, a distance of about a mile — there is moderate potential for finding archaeological remains, said Tom Chadderdon, an investigator with the Louis Berger Group Inc. 

That’s because land between rivers such as the Mississippi and bluffs was “optimum for camps or small villages,” he said.

The standard investigatory practice is to dig holes 2 feet square every 50 feet or so. In this case, that would be about 83 “shovel tests” over the course of the route, he said.

This week, the crew worked on a short stretch of Howell between Rockingham and 1st Street, and nothing significant was found, clearing the way for construction. They will return later this fall or next spring, depending on the weather, to finish the testing to the base of the bluff. 

If something significant is found — a fire hearth, for example — the crew would investigate further, but there is enough lead time built into the project that there likely would be no hold-up in construction, Chadderdon said.

In addition to Indian artifacts, the crew is looking for remains from later times, such as remnants of a long-gone trolley track or an early 1900s sewer, but they aren’t expecting much, he said.

Wednesday’s dig was the latest work the firm has done. The company’s research actually began more than two years ago with investigators poring through old records, archives and maps for written evidence of Indians as well as early European settlement.

Investigators checked out buildings, such as old homes, that might be affected by the project and found none of historic significance, Chadderdon said.

The diversion tunnel will be built in three phases over 4 1/2 to five years. Once the archaeological survey is finished for this phase, nothing more will be needed because the engineering firm already has determined that the potential for finds in the two other phases is insignificant, Chadderdon said.

The second phase between the bluff and the field at Williams Intermediate School will be dug almost entirely through bedrock, and the third phase between Williams to Northwest Park shows little potential based on previous research, he said.

The historical and archaeological research is costing about $54,000, Leabhart said.

The overall sewer construction project is estimated to cost $45 million, although that number is likely to increase because of inflation and other factors.

The project is aimed at relieving pressure on the existing sewer infrastructure and opening up parts of north and northwest Davenport to development.