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An ordinance amending Sections 15.64.010, 15.64.130, and 15.64.131 of the Metropolitan Code of Laws pertaining to the residential infill regulation of artificial turf, multi-family structures, infill tree credits, and development plan submission requirements; and requiring commensurate updates to the Stormwater Management Manual.
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WHEREAS, as Nashville’s built environment continues to grow, existing neighborhoods are experiencing additional development not envisioned by their original drainage systems; and
WHEREAS, continued development increases impervious surfaces and the volume of stormwater runoff which contributes to flooding, streambank erosion, and water quality degradation; and
WHEREAS, installations of artificial turf are often designed to route water rapidly away from sites instead of infiltrating the water into the ground like natural vegetation, thereby increasing the flow of water from properties into Metro’s storm sewers and streams; and
WHEREAS, the Metropolitan Department of Water and Sewerage Services (MWS) has developed a policy to regulate turf installations to account for additional runoff; and
WHEREAS, mature trees reduce stormwater runoff which helps mitigate flooding and improves stream water quality; and
WHEREAS, mature trees provide many other benefits to our community, including heat island mitigation, wildlife habitat, reduced air pollution, carbon sequestration, and increase property values; and
WHEREAS, residential infill projects have resulted in the loss of large canopy trees in neighborhoods, and the existing tree credit for residential infill projects is rarely utilized; and
WHEREAS, MWS has developed a new infill tree credit for inclusion in the Metro Stormwater Management Manual (SWMM) that recognizes the ability of existing trees to reduce or eliminate the traditional stormwater control measures required for development which should also result in greater retention of urban canopy; and
WHEREAS, current permitting of regulated residential infill is limited to individual or multiple single-family and two-family structures in the SWMM and the Stormwater Code; and
WHEREAS, certain residential infill projects with three-family or more structures may create as much or more impervious area than individual or multiple single-family and two-family structures infill; and
WHEREAS, these multi-family structures should likewise be included within residential infill provisions of the Stormwater Code and SWMM; and
WHEREAS, these revisions will help mitigate flooding and stormwater runoff across Nashville and Davidson County.
NOW, THEREFORE, BE IT ENACTED BY THE COUNCIL OF THE METROPOLITAN GOVERNMENT OFNASHVILLE AND DAVIDSON COUNTY:
Section 1. That Section 15.64.010 of the Metropolitan Code of Laws is amended by deleting the definition of “Infill (regulated residential)” and replacing it with the following:
"Infill (regulated residential)" means the creation of eight hundred to fifteen thousand square feet of additional net impervious area (IA) for a residential dwelling(s) and any associated improvements on the property through new development, redevelopment, or rehabilitation in existing neighborhoods.
Section 2. That Section 15.64.010 of the Metropolitan Code of Laws is further amended by deleting the definition for “Residential property” in its entirety.
Section 3. That Section 15.64.130 of the Metropolitan Code of Laws is amended by deleting Subsection A in its entirety and replacing it with the following:
A. Individual residential dwellings in any given area that do not alter a drainage channel, do not alter the natural ground elevation or vegetation by an amount greater than specified in the technical guidelines to be issued by the metropolitan department of water and sewerage services, or do not meet the definition of regulated residential infill;
Section 4. That Section 15.64.131 of the Metropolitan Code of Laws is amended by deleting Subsection D thereof in its entirety and replacing it with the following
D. Prior to the net addition of at least eight hundred square feet of impervious area or issuance of a building permit, a sufficient development plan prepared and stamped by a licensed land surveyor or professional engineer and supporting information required by the latest version of the regulated residential infill guidance document shall be submitted to and approved by the metropolitan department of water and sewerage services.
Section 5. The Metropolitan Department of Water and Sewerage Services shall prepare updates to the Stormwater Management Manual Standards commensurate and consistent with the Stormwater Code revisions adopted herein, including, without limitation, compatible provisions for (a) artificial turf installations; (b) three-family or more multi-family structures; (c) tree credits for residential infill; and (d) development plan submission requirements.
Section 6. This Ordinance shall take effect from and after its passage, the welfare of The Metropolitan Government of Nashville and Davidson County requiring it.
Agenda Analysis
Analysis
This ordinance, as amended, amends Sections 15.64.010, 15.64.130, and 15.64.131 of the Metropolitan Code of Laws regarding the residential infill regulation of artificial turf, multi-family structures, infill tree credits, and development plan submission requirements; and requiring commensurate updates to the Stormwater Management Manual.
The ordinance would update the definition of “Infill (regulated residential)” in Section 15.64.010. The current definition means “the creation of eight hundred to fifteen thousand square feet of additional net impervious area (IA) for a residential dwelling(s) on the property through new development, redevelopment, or rehabilitation in existing neighborhoods.” The proposed ordinance would add “any associated improvements on the property” to the calculations for additional net impervious area.
The ordinance would also remove a definition for “residential property” from Section 15.64.010. The current code defines “residential property” as “any property whose primary use, as shown on the use and occupancy permit issued by the Department of Codes Administration, is residential single-family or residential two-family.” The ordinance, as amended, would also delete the definition of “non-residential property” from Section 15.64.010. The current code defines “non-residential property” as “a parcel of property that is not a residential property as defined in this section.”
The ordinance additionally changes a requirement for the Department of Codes Administration to exempt building permit applications from review for a possible need for drainage plans in Section 15.64.130. The current code allows single-family and two-family individual residential dwellings to be exempt from review when they do not alter a drainage channel, the ground elevation or vegetation as specified by the Department of Water and Sewerage Services (“Metro Water”), or do not meet the definition of regulated residential infill. The proposed ordinance allows this exemption for individual residential dwellings under the same conditions.
The ordinance further changes Section 15.64.131(D). The code now requires a sufficient development plan and supporting information as required by the latest version of the regulated residential infill guidance document to be submitted and approved by Metro Water before the addition of at least 800 square feet or impervious area of the issues of a building permit. The proposed ordinance would also require that the sufficient development plan be “prepared and stamped by a licensed land surveyor or professional engineer.”
Lastly, the ordinance requires Metro Water to prepare updates to the Stormwater Management Manual Standards that are consistent with the proposed revisions to the Stormwater Code. These revisions would include compatible provisions for artificial turf installations, three-family or more multi-family structures, tree credits for residential infill, and development plan submission requirements.