Don Moss recommends the city clean the Glen Cairn stormwater pond, to prevent future flooding.

An engineer hired by the City of Ottawa says the Glen Cairn stormwater pond should be cleaned to help prevent future floods in the neighbourhood.

Don Moss, an engineer with Greenland International, told the city's planning and environment committee Tuesday that mud and sediment accumulate in stormwater ponds over time, so they hold less water than they were originally designed to. Moss said that might have contributed to the flooding Glen Cairn residents experienced after heavy rains on July 24.

"The fact that we did have rain before the major event took place, that meant that there was already water in the storm management facilities," Moss said. "We are interested in exploring the facility bottom."

Kanata South Coun. Peggy Feltmate said the city should have been aware of potential sediment buildup before July's flood.

Feltmate said she wants city staff to produce a report detailing when the Glen Cairn stormwater pond was last inspected and cleaned.

Back in September, city engineer Ted Cooper suggested that the stormwater pond's design may be responsible for chronic flooding in Glen Cairn.

Cooper said a 2003 study showed water in the pond rises to an elevation of over 95.6 metres, while basements in the neighbourhood were built at or above 94.5 metres, based on a 1973 grading plan that set that as the level of the flood plain. According to Cooper, water could flow more than a metre downhill before gathering in Glen Cairn basements.

Cooper sent a letter to city councillors representing west-end wards and to the Glen Cairn Community Association, alerting them to the problem. After receiving the letter, at least one councillor asked staff to review the findings and report back.