After 26 years and more than $300 million, work across 650 acres of Spring Valley and American University to deal with the residue of World War I weapons development might be nearing its end.

The target for wrapping up the job is July 2020, according to the project’s manager,

Dan Noble of the U.S. Army Corps of Engineers. “Groundwater is the big up-in-the air issue,” Noble said Tuesday. “I’m a little unclear how long that will take.”

A new round of testing of samples from monitoring wells is underway, the first in about four years. Results are expected in about a month. Earlier testing has shown levels of arsenic and perchlorate in some locations that exceed safe levels for drinking water. Arsenic can be lethal in high doses and perchlorate, an explosives oxidizer that dissolves easily, can be absorbed by edible plants and disrupt the thyroid gland’s regulation of metabolism.

Noble was among about 30 people who turned out, with other agency officials and community residents, to the basement of St. David’s Episcopal Church in the Palisades for a bi-monthly meeting of the Restoration Advisory Board.

What, if anything, will be done about the tainted groundwater is not clear. The Army Corps of Engineers manages contamination based on the risk, officials said. For example, in Spring Valley, the Corps has concluded there is no “unacceptable risk for current land use” because the “groundwater is not used as a drinking water source.”

Dave Tomlinson of the D.C. Department of Energy and Environment’s toxic substances division said the city’s goal is to make sure groundwater meets safe drinking water standards. When a Board member asked what circumstances might prompt groundwater being tapped for drinking, a member of the audience jumped in to offer the possibility of an oil spill on the Potomac River or poisoning of the reservoirs.

But treating the contamination comes with its own risks and costs. Tomlinson said that the results of new groundwater tests will help guide the response. “We are fairly close to drinking water standards here,” he said.

Groundwater monitoring began in 2005 and 56 wells have been installed to different depths around the site, with 27 surface sites tested. Wells beside AU’s Kreeger Hall have shown perchlorate at levels above drinking water, according to officials, while arsenic levels have exceeded the standard in one well on Glenbrook Road.

The landscape gradient goes toward the Potomac River, with officials saying the water moves slowly through the ground and lower rock.

The project, its area covering 1,600 private residences, began after a utility contractor digging a ditch in 1993 discovered ordnance. Excavations have been carried out over the years to remove contaminated earth and hazardous materials. Officials reported that final geophysical surveys for potential WWI munitions involve 92 residential sites and 13 federal or city properties. Recently, probing for “anomalies” detected a piece of metal on a home site that turned out to be part of residential water sprinkler system.

Property owners are compensated for the damage done by intrusions, which add to project costs. Noble said that an AU-owned house had to be completely removed at one ongoing project site and that a lease is being paid to the university.

Removal of vegetation at places along Dalecarlia Parkway has drawn complaints about loss of the noise barrier and worry about making way for bamboo to invade. Officials said they are working with arborists on the issue.

Some concern was shown at the meeting about how money is spent. Project leaders are looking for a Technical Assistance for Public Participation advisor to support the Board. The field was narrowed to two potential companies, ATI, Inc., and Nspiregreen, LLC. A promising proposal from ATI involved tapping as an advisor a professor from Wyoming, prompting worry about travel expenses. Board members decided more research was needed before settling on a deal for the $25,000 per year contract.

The Board next meets November 12, 2019.