Planting Begins on Green Roof of Target Center

MINNEAPOLIS - (BUSINESS WIRE) - Installation of the 2.5 acre green roof vegetation on the City-owned Target Center begins today. Over the course of two days a 165 ton crane will hoist five truckloads of plant material, which includes 900 rolls of pre-grown vegetated mats of sedum and native plants for installation on top of the arena's main roof. More than 540 cu yards of soil is being blown onto the rooftop between 120'– 165' in the air, using a blower truck. The roof is the largest green roof in Minnesota and, at the time of design, the fifth largest green roof in the United States.

The green roof is installed on a state-of-the-art waterproofing membrane which includes a leak detection system called Electro Field Vector Mapping (EFVM). The membrane will help withstand constant dampness, high alkalinity, and exposure to plant roots, fungi, and bacterial organisms as well as varying hydrostatic pressures.

The green roof features a 2.75" growing zone in the center of the main arena roof structure and a deeper 3.5" growing zone around the perimeter where the structural capacity is greater to maximize storm water retention and plant vigor. The pre-grown mat of sedum and native plants creates the base of the green roof system and will be complemented by additional plantings of plants native to Minnesota's prairies once the roof is installed to enhance plant diversity and ecological resilience.

To complete the roof by Fall 2009, 11 miles of sustainable, water-efficient irrigation lines will be installed and 14,000 concrete pavers for firebreaks and roof protection will be laid.

Green roofs provide ecological benefits by reducing the negative effects of hard surfaces like traditional roofs on stormwater quality, volume, rate, and temperature on the receiving waterbody, in this case, the Mississippi River. At 113,000 square feet, almost 3 acres, this green roof has potential for mitigating stormwater runoff from a significant amount of impervious surface in a downtown location where space does not permit use of other Low Impact Development Techniques to mitigate for the negative effects of hard surfaces on receiving waterbodies. Positive impacts on local water bodies are valuable in a City that prides itself on its legendary waterbodies: The City of Lakes in the Land of 10,000 Lakes.

The green roof design team includes Leo A Daly, Kestrel Design Group, and Inspec; locally-operated Stock Roofing, a Tecta America company, is replacing all of the roofs on the Target Center and installing the extensive green roof.

While the project called for 50% recycling of materials, the Tecta team has set its own goal of 100%, resulting in an estimated 450 tons of existing rock and 590 tons of existing pavers, 140 tons of existing roofing membrane, and more than 60 truckloads of existing roof insulation.

The installation and ongoing maintenance of the green roof is the last stage of a necessary roof replacement project that also includes replacing all 29 smaller roofs on five levels. The cost of roof replacement for all 30 roofs is $5.32 million and is paid for using a set-aside capital fund for improvements.

The public may view the installation of the Target Center green roof from the cam capturing the construction of the Twins Ballpark.

ROOFTOP MEDIA ACCESS ON SATURDAY CAN BE ARRANGED BY CALLING Krista Bergert, CPED Communications, 612 673 5015 by Friday close of business.

Krista Bergert
CPED Communications
612 673 5015
cell: 612 360 8702
or
Sian Imber
LEO A Daly
202 841 0999
or
Lori Keenan
Tecta America
847 902 2905