Half a year after study found issues with Oxford Avenue pipelines, another sinkhole formed

Posted at 12:08 PM, Jul 02, 2019

ENGLEWOOD, Colo. — On Monday, for the third time in four years along one block in Sheridan, the ground caved and a large sinkhole opened up.

Monday’s sinkhole developed at S. Santa Fe Drive and W. Oxford Avenue, just outside Englewood city limits. Flooding is common in the area after heavy rains.

The city of Englewood hired a contractor to study this problem and determine a solution after a sinkhole formed in this area in 2018. The findings were released in December and called for certain aspects of the pipeline to be fixed in order to prevent a future sinkhole.

At a news conference Tuesday afternoon, Englewood addressed that study.

"I think we're taking it very seriously," said Maria D’Andrea, director of public works for the City of Englewood.

But, D'Andrea said the funding simply doesn't exist at the moment to fix a vast network of aging storm water drainage pipes underneath the city.

"Essentially, this area is a bottleneck," D'Andrea said. "It gets surcharged and it fails."

D'Andrea said the city has about $950,000 in a storm water utility fund, but it would take $45-$75 million for infrastructure improvements in just the flood plain alone.

"Right now, we don’t have the funding in place in order to replace it," she said. "Obviously, if it’s failed multiple times — this is a high priority. But, we do need to identify the funding first."

She said one option for funding would be raising the storm sewer utility rate, then bonding against that rate increase to get cash up front.

Homeowners are experiencing déjà vu, and they’re calling out the city for it.

“Stop putting lives at risk," said Vicki Hoffmann, who owns a home on nearby Bannock Street. "Take care of it. Be responsible.”

While none of the three sinkholes were deadly, Englewood flooding did prove deadly in July 2018 when a woman was trapped in the basement of a home where she was cat-sitting.

That home is just a block from Hoffmann's home, which has also flooded.

“It was filled to the ceiling in her basement,” she said.

Toni Arnoldy, with City of Englewood community relations, said they are working on a temporary fix until the new pipe comes in in a few weeks.

The last time this stretch of Oxford Avenue saw a major issue was July 25, 2018, when a driver in a RAV4 fell into a sinkhole that had opened on eastbound W. Oxford Avenue near Natches Court, just east of the Chick-Fil-A and only about 30 feet away from Monday's hole. The driver was able to escape. A few years earlier, on June 15, 2015, Sgt. Greg Miller with the Sheridan Police Department was driving eastbound on Oxford when the road gave way and his car dipped into a sinkhole east of Natches Court. He was also able to climb out to safety.

In the wake of the 2018 incident, the city of Englewood — which controls the pipeline, though the sinkholes occurred in Sheridan limits — contracted with a company called Calibre Engineering in September to do a study of flood-prone areas. The study had three objectives:

1. Complete a life safety assessment of flood-prone properties and identify flood-proofing techniques
2. Conduct an assessment of the Oxford Avenue pipe conditions
3. Update the 1999 Storm Water Outfall Systems Plan and identify capital infrastructure projects

That study, which was completed in December 2018, found several problems that could lead to future sinkholes along Oxford Avenue. In a few sections, officials found that the invert, or bottom, of the pipe was severely deteriorated beneath the sedimentation and the bedding had been washed out.

Calibre Engineering photos of Sheridan/Englewood pipeline from sinkhole

Aside from this and moderate debris, the study did not find anything else concerning.

If the invert deterioration was not repaired, the pipe would become deformed, which could cause the “potentially sudden failure of the pipeline,” according to the study. Additionally, losing the bedding material could lead to soil moving around more and building up in places.

This would compromise the structural integrity of the entire pipe segment, which could lead to “catastrophic failures, such as sink holes," according to the study.

As a result of these findings, officials with Calibre Engineering recommended using non-destructive technology to locate and quantify the soil loss.

The Englewood City Council will hold a public meeting next Monday, July 8 where the results of the study will be discussed.