Garden boxes designed to help prevent sewer overflows
homeowner Aaron Pierce says he can no longer be blamed for contributing to overflows of combined sanitary and storm sewers in the city.
Pierce took the step of disconnecting the roof downspout on his N. Pierce St. home from a pipe draining to the combined sewer in the street and preventing hundreds of gallons of clear water from entering the sewer during a storm.
That was no small accomplishment on his 30-foot-wide lot on the north side since there isn’t enough lawn to absorb all of the water coming off the roof. The city prohibits water from a property owner’s downspout from flooding a neighbor’s yard or causing ice to form on a sidewalk, street or alley.
Rainwater running off Pierce’s roof is diverted to a 10-foot-long StormGUARDen, a specially designed box filled with tubs of soil and topped with flowers and native grasses that can collect all the water from storms dropping up to 3 inches of rain. The drain pipe to the combined sewer is capped.
Pierce has watched the state-of-theart container garden fill in a storm to ensure it worked as advertised, he said.
“The really cool part of it,” said Pierce, is the overflow drain at the low end of the box positioned more than 10 feet from the home’s foundation. This feature allows him to integrate the StormGUARDen into the remainder of his backyard landscape, he said.
Pierce planted a separate flower garden downslope from the drain to receive the water.
The Milwaukee Metropolitan Sewerage District is spreading the word that owners of thousands of small city lots now have options for disconnecting their downspouts from combined sewers and helping to prevent sewer overflows. When combined sewers in central Milwaukee and the eastern half of Shorewood fill during heavy rains, they overflow into the deep tunnel. If the tunnel fills to capacity, excess wastewater in the combined sewers overflows into local rivers and Lake Michigan.
Work to be done this summer
MMSD has proposed spending more than $192,000 this summer to install 27 StormGUARDens, as well as 15 tiered rain gardens with retaining walls on steep slopes and 22 standard rain gardens on level lawns at a total of 64 residences in the combined sewer area of central Milwaukee.
These above-ground installations along with rain barrels and rooftop gardens are known as green infrastructure and provide alternatives to the more costly pipes, or gray infrastructure, traditionally used to collect stormwater.
MMSD has set a goal of working with property owners to install enough green infrastructure by 2035 to capture 740 million gallons of stormwater every time it rains. This summer’s installations will be considered demonstration projects to show other nearby property owners how they could help prevent clear water from filling the sewers, said Karen Sands, MMSD director of planning, research and sustainability.
The MMSD commission’s policy and finance committee on Monday recommended awarding the installation contract to The Green Team of Wisconsin Inc., a Milwaukee-based company. Blue Skies Landscaping, a program of Walnut Way Conservation Corp., is a subcontractor for the project.
The district commission will act on the contract at its June 21 meeting.
The 64 properties are located in three of the most densely developed neighborhoods — Silver City, Burnham Park and Pulaski Park — on the city’s south side, according to Sands. The Silver City neighborhood is generally west of S. Layton Blvd. and north of W. Greenfield Ave. Homeowners in the program will not have to pay for the installation.
Milwaukee company’s design
The value of each of these green infrastructure installations on private properties — $2,000 for a fully-planted StormGUARDen — will be reported to the IRS for tax purposes, district officials said.
The patent-pending StormGUARDen was designed by Carrie Bristoll-Groll, principal civil engineer and CEO at Stormwater Solutions Engineering LLC in Milwaukee. The 10-foot-by-3-foot box combines the features of rain garMilwaukee dens and rain barrels, she said.
Rainwater from a downspout first flows into a stone-filled trough in the center of the box. As the trough fills, the water drops into five separate and removable tubs containing soil and layers of gravel. The gravel holds water to sustain plants during dry weather.
Excess water from the tubs overflows into the bottom of the box that itself can hold 350 gallons of water, around the same capacity as six and one-half rain barrels, Bristol-Groll said. As this reservoir fills, the water is released through small openings to the lawn.
Stormwater Solutions received a grant from The Water Council, a nonprofit group based at the Global Water Center in Milwaukee, to install 10 of the StormGUARDens in 2017 as a pilot project. Pierce agreed to test out one of those and another one is located next door, at the home of Harlan Groll, Bristol-Groll’s son and a long-time engineering technician at Stormwater Solutions. Groll now works as operations manager for StormGUARDen.
This month, MMSD paid for installing a StormGUARDen at the Shorewood Public Library as part of a separate demonstration project. MMSD is offering to pay for a limited number of rain barrel and garden installations, and even a few StormGUARDens, this summer in the village’s combined sewer area.