Green Infrastructure for the Central Corridor Light Rail Transit Project
From 2011 to 2013, the full reconstruction of University Avenue in Saint Paul for the Central Corridor Light Rail Transit (CCLRT) presents a unique opportunity to improve the quality of stormwater runoff from the Corridor that will not be seen again. Assistance from the Clean Water funds will augment large investments being made by Capitol Region Watershed District, Saint Paul, Ramsey County, and Metropolitan Council implementing highly visible, green infrastructure practices in this transportation corridor to achieve significant stormwater volume reduction and water quality improvements. Other environmental benefits include improved aesthetics, better air quality, and reduced air temperatures.
The Corridor is highly urbanized and comprised of primarily commercial and industrial land uses with a small amount of residential property. The existing drainage system conveys untreated stormwater runoff from paved surfaces to the Mississippi River, which is impaired for turbidity, nutrients, and bacteria.
Four categories of green infrastructure practices will be constructed to achieve the runoff reduction and water quality goals of the project. These are: integrated tree trench system, stormwater planters, rain gardens, and infiltration trenches.
The integrated tree trench system will be constructed on both sidewalks along 5.2 miles of University Avenue. Street runoff will be directed to infiltration trenches while runoff from sidewalks will go to pervious pavers and structural soils. The structural soils will support the trees that provide evapotranspiration, infiltration, and nutrient uptake. Ten additional green infrastructure practices will be constructed on adjacent streets to University Avenue to further green this Corridor.
(b) $2,800,000 the first year and $3,124,000 the second year are for grants to watershed districts and watershed management organizations for: (i) structural or vegetative management practices that reduce storm water runoff from developed or disturbed lands to reduce the movement of sediment, nutrients, and pollutants or to leverage federal funds for restoration, protection, or enhancement of water quality in lakes, rivers, and streams and to protect groundwater and drinking water; and (ii) the installation of proven and effective water retention practices including, but not limited to, rain gardens and other vegetated infiltration basins and sediment control basins in order to keep water on the land. The projects must be of long-lasting public benefit, include a local match, and be consistent with TMDL implementation plans or local water management plans. Watershed district and watershed management organization staff and administration may be used for local match. Priority may be given to school projects that can be used to demonstrate water retention practices. Up to five percent may be used for administering the grants (2010 - Runoff Reduction)
Eight biorention basins and three infiltration trenches were installed. An estimated reduction of 9.05 tons/yr of sediment, 134.141 acre-ft/yr of stormwater runoff, and 108.7 lbs/yr of phosphorus was achieved.