A report to the City of Winnipeg's water and waste committee says a pilot project that built a back lane intended to reduce drainage into the city's sewage system has failed to confirm the design works — or provide any usable data.

The $328,000 the city spent on the project — 40 per cent higher than the cost of a standard back lane renewal — appears to have returned little value for the money, according to the report.

"Anything that could have gone wrong did go wrong … not even done wrong, done badly," said St. Vital Coun. Brian Mayes, who was on the mayor's environmental advisory committee when the contract for construction of the lane was green-lit in 2014.

The "green back lane" was constructed in 2015 in a lane bounded by Wentworth Street, Stafford Street, Dorchester Avenue and Grosvenor Avenue.

Instead of a standard poured concrete back lane, the project involved installing permeable paving stones in the centre of the lane over top crushed rock.

Water would "infiltrate in the centre of the lane and be collected by the subdrain system, reducing or delaying flows to the combined sewer system," according to the report, which is set to be presented to the water and waste committee at its Thursday meeting.

The back lane was completed without the proper materials in place, in a location that wasn't properly monitored before installation and wasn't maintained to design specifications (John Einarson/CBC)

"While the lane has performed reasonably well in the short term some settlement has occurred and the lane has not been maintained in accordance with the design recommendations," the report says.

It also notes other issues, including the fact the original planned location for the green lane was changed to the existing location, without doing pre-construction monitoring.

That meant the stated purpose of the pilot project — to measure the effectiveness of the design — wasn't accomplished.

"The effectiveness of the land drainage flow reduction or delay could not be evaluated because the location of the pilot needed to be changed due to poor sub-surface soil conditions," the report says.

"Preconstruction flow monitoring data was not available for the new lane location."

As a 1st step, pilot 'pretty alarming': Mayes

As well, an important construction material wasn't added between the paving stones and a necessary layer of fabric under the roadbed wasn't installed, the report says.

Mayes, who has fought for funding to replace multiple gravel back lanes in his ward, isn't impressed.

"Years later to see that it wasn't put in correctly, it wasn't maintained correctly and there's no way of knowing what what the results were — yeah, that's disappointing," Mayes told CBC News.

Water and waste committee chair Coun. Cindy Gilroy (Daniel McIntyre) was reluctant to condemn the missteps outlined in the report on the back lane project, but did vow to ask some questions at Thursday's meeting.

"I do have questions. Is something working in other cities? Is it something that could work here? Is our soil conditions not conducive to that?" Gilroy told CBC News.

Mayes was more aggressive in his comments, raising concerns about potentially more expensive green infrastructure upgrades for Winnipeg's sewer system, given the issues that arose with the installation of a single block of green back lane.

"We better have council involved and the public involved if we are going to do $100 million worth of green infrastructure, because if this is our first step, that's pretty alarming," Mayes said.

St. Vital councillor Brian Mayes says the failed back lane pilot project is 'disappointing.' (CBC )

Water and waste staff lists a series of "lessons learned," from the failed back lane project in their report.

Those include tendering any future green back lane projects with other lane renewals to get a better price, conducting more thorough geo-technical investigations prior to construction, and establishing better communications with city staff on various aspects of the project.