University of Wisconsin-Green Bay
OP-23: Stormwater Management

UW – Green Bay has a Municipal Separate Storm Sewer System (MS4) General Permit. In 2008, a contractor conducted a stormwater analysis to estimate annual stormwater loadings (sediment and phosphorous) for all storm sewer outfalls. This establishes a base pollution load and the pollution reduction resulting from the existing stromwater management measures on campus. Currently, the campus uses best management practices of rooftop, parking and sidewalk disconnection, swale drainage, and wet detention ponds to reduce impact of total suspended solids (TSS). As of the 2008 study, the BMP in place have already met the TSS reduction level of 40% required by 2013.

UW-Green Bay has underground concourses running between the majority of academic buildings to allow easy access throughout the winter months. The Instructional Services Building had a green roof on its concourse, installed in 1969 when the building was constructed.

Four campus ponds serve as detention ponds: Upahki, Teal, the large golf course pond and the detention pond serving the Kress Events Center. Of these four, only the detention pond serving the Kress Events Center is an engineered detention pond. Detention ponds are depressions in the ground surface with a permanent pool of standing water. During rainfall events, stormwater runoff from storm sewers or grassed swales enters the detention pond where some of the sediment in the runoff settles out before it flows downstream.

Grassed swales drain most of the non-curbed roadways on campus and can be seen adjacent to these roadways, such as South Circle Drive. Grassed swales have the ability to treat stormwater and allow for infiltration, whereas the alternative storm sewer system does not.

The University of Wisconsin-Green Bay storm sewer system was constructed in the late 1960’s and early 1970’s during the initial construction phases of the university. At that time, the City of Green Bay did not have storm sewers that extended to the campus site. In order to provide stormwater drainage for the campus area, storm sewers were installed that discharge to the nearby waters of Mahon Creek and the bay of Green Bay. Subsequent development necessitated drainage for a large part of campus that was provided by construction of storm sewers that lead to a pond on the golf course. The detention pond serving the Kress Events Center was constructed in 2007 to provide stormwater runoff pollution control for new parking lots and building expansion of the Kress Events Center. Over the years, the university has constructed and maintained a storm sewer system that is completely separate from the system operated by the City of Green Bay. For most of its history, UW-Green Bay has not been required to treat its stormwater nor was the campus charged any type of permitting fees.