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An ordinance amending Metropolitan Code of Laws Section 15.44.050, Waters Diverted from Public Sewerage, by deleting subsection E. Green Roofs.
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WHEREAS, Metropolitan Code of Laws Section 15.44.050(E) provides for a rebate to privately-owned property owners within the combined sewer area of the Metropolitan Government for installation of a properly functioning green roof which eligibility requirements are set forth therein; and,
WHEREAS, since the creation of the rebate in 2012, the rebate has never been used; and,
WHEREAS, under the new stormwater regulation revisions it will be far easier for green roofs to meet Metro’s water quality standards, which should be a more effective strategy to increase their utilization.
NOW, THEREFORE, BE IT ENACTED BY THE COUNCIL OF THE METROPOLITAN GOVERNMENT OF NASHVILLE AND DAVIDSON COUNTY:
Section 1. That the Metropolitan Code of Laws Section 15.44.050, Waters Diverted from Public Sewerage, is hereby amended by deleting subsection E. Green Roofs, in its entirety.
Section 2. Amendments to this legislation shall be approved by resolution.
Section 3. This ordinance shall take effect from and after its final passage, the welfare of The Metropolitan Government of Nashville and Davidson County requiring it.
Agenda Analysis
Analysis
This ordinance deletes the rebate program for the installation of a functioning green roof that complies with certain requirements under that rebate provision established under Section 15.44.050.E. This rebate was created in 2012 and has never been used. According to the Department of Water Services (MWS), under the new stormwater regulation revisions, it will be easier for green roofs to meet Metro’s water quality standards. Green roofs can now receive up to a 90% runoff reduction credit, which will increase their utilization and incentivize green roofs more than the existing green roof rebate program
Under Section 15.44.050 of the Metro Code of Laws, green roofs on privately-owned properties installed after September 7, 2012 are entitled to a credit against month sewer charges. The credit is $10 multiplied by the number of square feet covered by the green roof, with a maximum credit of $500,000 annually. The credit would be spread out into a monthly credit for up to 60 months. The green roof is required to be a building roof covering placed over a minimum of fifty percent of a building’s rooftop containing, at least, a waterproof membrane layer, a drainage layer designed such that roof drains can be inspected and cleaned, a growth medium at least four inches in depth, and a vegetation layer with at least eighty percent live, hardy, drought-resistant plants. The ordinance under consideration would eliminate this credit.
New stormwater regulation revisions will allow green roofs to receive up to a 90% runoff reduction credit, which will allow for a green roof to meet a site’s full water quality requirement in most cases. Under the previous stormwater regulations, green roof only provided 45% to 60% runoff reduction credit. In addition, since introduction of this rebate in 2012, green infrastructure has become a requirement for most development sites.