Public works officials are investigating how to repair a sinkhole the size of a small car that opened up on West Hollis Street last week, impacting 150 feet of sewer pipe and injuring a city employee who responded to the scene.

A Street Department laborer was splashed in the eyes with sand and raw sewage while attempting to repair the sinkhole, which emerged Wednesday, Oct. 16.

City Engineer Steve Dookran said an aging sewer pipe buried about 16-20 feet underground collapsed near the corner of West Hollis and Pine streets, allowing the pavement above it to cave in.

The city is now investigating whether it will be necessary to replace the entire length of sewer pipe that was impacted, or whether a less costly liner can be used to patch up the area.

“We know what it is,” Dookran said. “Sinkholes – we routinely work with them. It’s just how we go about repairing the sinkhole is what we’re trying to figure out.”

A police report indicates officers were first notified of the incident around 12:43 p.m. Wednesday. Officers were called to the area of West Hollis and Pine streets, where an elderly man was trying to steer traffic away from the hole, then the size of a basketball.

Dookran said a 2-foot-wide sewer pipe dating to 1888 collapsed underground. The concrete pipe was not reinforced, making it more fragile than some of the other clay and brick pipes in the city dating to around the same time period.

The sinkhole eventually grew to between 8 feet and 10 feet long. During a Board of Public Works meeting last week, DPW Director Lisa Fauteux said it was about the size of a mid-size sedan.

Crews from the Street Department attempted to excavate the sewer pipe and repair it Wednesday night, but eventually gave up and filled the hole with gravel. Dookran said the pipe is now partially blocked, requiring the city to pump sewage around the obstruction.

“They realized that it was too deep and too much for them to handle, so they filled it in (and) kept bypass pumping, because the pipe has a substantial amount of flow and you can’t allow it to back up and enter into people’s homes,” he said.

Dookran said there were no injuries when the sinkhole opened, but a worker was injured later in the day when a bladder burst and sewage shot through a manhole, splashing him in the face.

The city called in a contractor with a bigger pump for assistance on Thursday. The city is being charged $9,950 for a two-week equipment rental, according to an estimate provided last week by Park Construction Corp.

Dookran said crews are now pumping water out of a manhole on West Hollis Street, transporting it through a tube on the street and piping it down into the next manhole.

The city is still trying to determine the best way to fix the broken sewer pipe. The job is complicated because the ruptured pipe is sitting underneath a significant bank of phone lines, which are encased in concrete. A water pipe also runs through the same area.

In the mean time, the left lane of West Hollis Street is closed to traffic, and a police officer is posted at the scene to direct traffic away from the sink hole.

Fauteux said the Street Department employee who was injured Wednesday received only minor injuries and has since returned to work.

During an interview Monday, Fauteux declined to comment on what happened, saying only that “somebody got something splashed in their face.”

She said the Department of Public Works was not in possession of any written records that describe the injury and referred all questions to the city’s Risk Management office.

“I know of the incident, but that doesn’t mean that I look at all of the paperwork associated with it,” she said.

The Telegraph filed a Right-to-Know request with the Risk Management office Monday seeking records regarding the injured worker. The newspaper is awaiting a response.

The Telegraph also requested records directly from the Street Department, which falls under the umbrella of the Department of Public Works. Three documents were provided, including an occupational injury report filed on Thursday, Oct. 17.

The injury report indicates an employee was splashed in the eyes with sewerage and sand while the repair was underway on Wednesday.

Fauteux did not mention the injury when she briefed the Board of Public Works about the sinkhole Thursday. Responding to questions about the incident this week, Fauteux said she was not aware of the of injury during Thursday’s meeting.

“I don’t think the public’s that interested in every bump and bruise a public works employee gets,” she added.

Jim Haddadin can be reached at 594-6589 or jhaddadin@nashua telegraph.com. Also, follow Haddadin on Twitter (@Telegraph_JimH).