Menomonee Valley Earthcache: Bioretention Facility
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This Earthcache is located at the Bioretention Facility on 25th & Canal Street, a project constructed by the City of Milwaukee through a partnership with Milwaukee Metropolitan Sewerage District. (Don't let the map or satellite image fool you. They are out of date. This cache is NOT located on train tracks. The tracks have been removed and Canal Street has been rerouted. This is a curbside cache.)
The Menomonee Valley is a U-shaped land formation along the southern bend of the Menomonee River in Milwaukee, Wisconsin. Glacial melt water formed the Menomonee Valley over 10,000 years ago when the Green Bay Lobe of the Wisconsin Glaciation retreated and eroded a swath four miles long and half of a mile wide. Today, it is roughly bounded by the 6th Street Viaduct near the river confluence and Miller Park stadium to the west.
A vast marsh once extended from Lake Michigan almost to Miller Park. Steep wooded bluffs rose above both sides of the Valley. In its original state, the Valley provided habitat for plants and animals, supplying abundant food for generations. Surrounding wetlands collected rainwater and then slowly released it, providing clean water to springs and seeps along the bluffs. James Buck, pioneer and historian, wrote in the 1830’s, “All the marsh proper… would, in the spring, be literally alive with fish that came in from the lake… And the number of ducks that covered the marsh was beyond all computation.”
In the mid-1800’s, Milwaukeeans filled the marsh to create dry land. The Valley floor was raised an average of 22 feet and the north rim lowered by as much as 60 feet. They straightened the river and cut canals to provide shipping routes. Businesses moved into the Valley. These changes provided jobs for thousands of people, but damaged the Valley’s natural resources. In the late 1900’s, industrial decline left the Valley an isolated and blighted area with contaminated land and abandoned industrial buildings.
When rain and snow fall in a natural area, the water is absorbed and filtered by the trees, plants and the ground. But when rain falls on hard surfaces, like streets and buildings, it cannot be absorbed. Stormwater is the rain that falls on the hard surfaces and collects dirt, salt, garbage, pet waste, oil from cars and other pollutants. Have you ever watched stormwater flow into storm drains? That dirty water may flow directly into our rivers and lakes, making fishing and swimming unsafe.
The Milwaukee area has abundant water resources – lakes, rivers, ponds and wetlands. But what happens when there is too much water? Unfortunately, Milwaukee County is especially vulnerable to flooding. Why? For 10,000 years, this area had a natural balance of prairies, wetlands, forests and rivers that absorbed rainfall and slowed water movement. In more recent history, expanding urban and suburban development has upset this balance. Houses, buildings, streets, sidewalks, driveways and parking lots have replaced our natural areas. These hard surfaces prevent rain from soaking into the ground. Instead, rain flows directly into storm sewers and waterways – causing fast currents and downstream flooding.
Businesses, neighbors and community groups are working to once again change the landscape of the Valley by balancing its economy and ecology. Within the last several years, the Milwaukee Metropolitan Sewerage District (MMSD) adopted new rules regarding the discharge rate of stormwater runoff from new development and redevelopment areas. Similarly, the Wisconsin Department of Natural Resources (DNR) adopted new rules regarding the quality of stormwater runoff discharged from new development and redevelopment areas. These new rules from both the MMSD and Wisconsin DNR were incorporated into the city of Milwaukee Municipal Code of Ordinances.
The plan for controlling storm water in the developing and redeveloping portion of the lower Menomonee Valley consists of regional bioretention facilities. Bioretention is a stormwater management practice that treats stormwater runoff using a 2 step process.
First, stormwater runoff is pumped into a graded basin, also known as a forebay, designed to remove pollutants by allowing sediment, such as sand and soil particles, to settle before being further treated.
Next, the partially treated runoff flows from the forebay to the second basin known as the bioretention basin. The partially treated stormwater infiltrates the soil medium which is a mixture of topsoil and sand designed to allow wetland plants to grow while also allowing contaminants to be filtered by the soil before the runoff is discharged into the environment. The plants that are grown here, including shrubs and brush, are native to the area.
The fully treated stormwater runoff is collected in a drain tile system and discharged into the Menomonee River . Other bioretention facilities allow the treated stormwater runoff to recharge groundwater aquifers. This system on 25th & Canal Street reduces runoff discharged into the environment through evapotranspiration (some runoff is soaked up by the plants and released into the air as water vapor) and improves the quality of runoff by filtering contaminants before being discharged into the environment.
To log a find for this Earthcache, you must perform the following:
1) Voluntary (no longer a requirement): With your “Found It” posting, include a picture of you, your team, or your GPS (if caching solo) next to the pond.
2) Email the cache owner with the answers to the following questions using the sign as your reference –
• This facility treats stormwater runoff from how many acres? Between what streets?
• What are at least 4 of the 6 listed benefits of this type of water treatment?
Additional Hints
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