Trucks are thundering back and forth on 42nd Avenue, Penn Avenue and Osseo Road hauling tons of dirt from an ever-growing hole in Crystal Lake Cemetery. So what is going on in the northeast corner of the cemetery? The City of Minneapolis Department of Public Works is constructing a storm water retention pond.
Storm water retention ponds are being built across the urban landscape for the retention and treatment of storm water run-off. New, larger storm sewer pipes that were laid along 42nd Ave last summer and fall will direct water into the pond to help prevent flooding when we have exceptionally heavy rains. The water will then be held in the pond where sediment will settle to the bottom. (Sediment holds nutrients that contribute to the pollution of the river and lakes where the storm water runs.) When the pond level reaches a certain height water will then flow out of the pond back into the sewer system and on into the Mississippi.
The pond in Crystal Lake Cemetery is being constructed to alleviate flooding that was occurring around 42nd and Queen and Russell Avenues. Whenever there was an extremely heavy rain, there would be more water in the storm sewers than they had the capacity to hold. Consequently, the water would come up through the manhole covers and flood the streets, often-rising high enough to come up to the front doors of homes and through the basement windows, flooding basements and eroding foundations. The City’s sewer system was built over 100 years ago and most of the sewer pipes are only three to four feet in diameter. Over the course of those years, we have created more impervious surfaces in our city, public spaces and yards. Parking lots, paved streets, driveways, patios and even the homes, buildings and structures that have been built do not allow the storm water to soak into the ground, so it runs off into a storm water sewer system that does not always have the capacity to transport it all.
The Crystal Lake Cemetery pond will be a “wet pond” meaning it will always have water in it, unless we are suffering a severe drought. The pond which is expected to be completed by mid to late June (weather permitting) will have walking paths around it, and be fenced on the west and south sides. There will be a guardrail on the east side along the alley and the north edge of the pond facing 42nd Avenue will be unfenced. Native vegetation will be planted on the edges of the pond to filter run-off into the pond.
The total project cost will be $4.5 million including the $1 million cost to procure the land from the cemetery. Other solutions to the flooding problem such as installing six-foot diameter storm sewer pipes all the way to the Mississippi would have cost $6 million and would not have provided the storm water treatment that the pond will provide. Installing the pond in the area where the flooding was occurring would have involved purchasing and removing all the homes and would have cost considerably more. The storm water retention pond in Crystal Lake Cemetery was determined to be the least expensive and most environmentally sound way to address the flooding problems in the area. For more information on the pond contact Mitchell Sawh, the Public Works engineer in charge of the project, at 612-673-2360 or mitchell.sawh@ci.minneapolis.mn.us.