When the city authorized dumping soil on land it owns across from the San Antonio Food Bank, it was in the midst of negotiating with the San Antonio Water System to swap the land for SAWS-owned property.

The problem: The city failed to tell SAWS officials or Councilman Ray Lopez, whose district encompasses both pieces of property, that the soil contained heavy metals flagged by environmental consultants as potentially harmful.

Lopez was excited about the pending land swap. He wanted the city to acquire the 12-acre property at Potranco Road and Texas 151 because he envisioned a sprawling athletic complex there.

The city and SAWS began negotiating a potential land swap in the summer of 2013, said SAWS CEO Robert Puente.

“We had a deal in spirit about six months ago,” Lopez told me. “I’d like to be able to say that’s my final legacy project.”

But the deal fell apart about a month ago, Lopez said, when SAWS caught wind that about 150,000 cubic yards of dirt contaminated by heavy metals had been dumped on the city-owned property across from the food bank and near Animal Care Services and a Pre-K 4 SA school.

“I think somebody (with SAWS) drove by and saw them dumping dirt, and somebody called someone else and said, 'Where did that come from?’” Lopez said. “Somebody on my staff said, 'Hey, I understand SAWS is asking if that was dome dirt.’ So we kind of started digging a little bit.”

(In the early 1990s, during construction of the Alamodome, the city hauled up to 500,000 cubic yards of contaminated dirt to low-income areas.)

This year, Lopez and SAWS dug up the truth.

The soil, they learned, had been hauled from land on which the city is expanding the downtown Convention Center, just across Interstate 37 from the Alamodome.

The city had selected Hunt-Zachry for the expansion, a $325 million project. Hunt-Zachry hired environmental consultants Geo Strata to test soil on the site for contaminants.

Geo Strata reported finding heavy metals — arsenic, barium, lead, mercury and selenium — that “exceeded regulatory levels” and recommended either reusing the dirt on-site or disposing of it off-site at an approved landfill. The soil “must be considered contaminated,” the report stated, “and should not be transported off-site and treated as clean fill material.”

But dumping the soil in an approved landfill would have cost the city $6 million. So the city sought a second opinion, hiring its own consultants, Raba Kistner Environmental Inc. That company concluded that the level of metals in the soil was not a concern. So the city directed Hunt-Zachry to begin dumping the soil and indemnified it from any future liability.

The dumping continued for about six months, Lopez said. He knew soil was being dumped on the city-owned land but had no clue about the conflicting environmental reports.

“Honestly, I didn’t ask, and I didn’t know about issues related to engineering and possible contaminants,” Lopez told me. “I would have much preferred to have known about it then and had a conversation with SAWS.”

The discovery by SAWS of the soil saga killed the swap, said Mike Frisbie, director of the city’s Transportation & Capital Improvements department.

“They were concerned about the soil that was placed there,” Frisbie said. “They just saw it as an obstacle to selling the property. For us, we don’t see it as an obstacle.”

The soil, though, was certainly an obstacle to swapping the property for Lopez’s promised land.

“Ultimately, we would have to turn around and sell these acres because we have no use for it,” Puente said. “When these kinds of things happen, you have to disclose it to the new buyer. There are two reports that can be interpreted in two different ways.”

For some reason, city officials felt that they did not have to disclose the conflicting reports to SAWS. And that’s a problem, Lopez said.

“If there is a lesson to be learned here, with an organization, certainly SAWS, which is a wholly-owned subsidiary of the city of San Antonio, it’s incredibly important to have openness,” he said. “Openness and communication has to be part of what we do.”

The councilman is planning a long week of communicating — with people other than city officials.

“I want to be able to hear somebody I have confidence in and recourse to,” Lopez said. “I want to feel incredibly confident, through multiple sources inside the city and out, about that. I want to make sure there’s not a public health issue.

“I mean, there’s a food bank and a school there. And we’re trying to dump this land on someone else.”