Title
Resolution Granting Joint Easement for Permanent Drainage into the S. Fifth Avenue Underground Parking Structure from the City of Ann Arbor to 330 East Liberty, LLC and 320 South Division LLC (8 Votes Required)
Memorandum
There is a resolution before you to approve a grant of a joint easement for permanent drainage into the S. Fifth Avenue Underground Parking Structure of storm water runoff by three properties located immediately adjacent to the new underground parking structure located on South Fifth Avenue. The easement will provide for the allocation collectively to be used by and between the three properties of not to exceed 12,500 CFT of surplus detention capacity at parking structure as outlined below.
In fulfillment of the goal to make the South Fifth Avenue underground parking structure as environmentally friendly as possible, the structure was designed to capture and detain storm water quantities well in excess of City and County requirements for the project. The considerable drop in elevation on this block produces a natural opportunity to capture storm water runoff from the adjacent properties east and north of the structure, thereby using some of the structure’s surplus storm water capacity to mitigate storm water runoff into the Allen Creek drain. Storm water from these properties currently flows unchecked and unfiltered into the city’s storm system.
In this section of downtown, very little storm water is able to infiltrate into the ground, and instead is rapidly conveyed through surface runoff into storm drains that feed into the Allen Creek drain and then to the Huron River. Storm water runoff from the initial half inch of rain, also known as first flush, tends to carry the most pollution as it washes automotive fluids, deicers, and other contaminants into the storm drains. The South Fifth Avenue parking structure’s excess detention capacity is an opportunity to detain and treat some storm water that currently flows uncontrol...
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