Item 7A PresentationItem 7A
Amendments to Ordinance No. 480 to add regulations for streamway buffer and permeable pavement (Ord. 480-VVVV)
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Sustainability Plan
Adopted in 2014 (Ord. No. 1104)
Part of City’s Comprehensive Plan, Southlake 2030.
Contains prioritized recommendations to maximize efficient use of public resources.
Summarize Sustainability Plan which combined components of various plans including environmental protection, water, stormwater, transportation, and fiscal responsibility. The term “sustainability”
means meeting present needs without compromising the needs of future generations. The term was first used in the VGOs of the Southlake 2030 plan.
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Background
Citizens Survey Strategy Map Southlake 2030 Plan
Key components of the City’s Strategic Management System. The Citizen’s Survey is biannual and informs staff of gap issues as expressed by the public. Those results are analyzed qualitatively
and developed into a strategy map, which forms the framework on which the City’s Comprehensive Plan is updated every 5 years. This plan, of which the Sustainability Plan is a part, makes
recommendations and provides a policy guide for the development of the City. These recommendations and policies may go into the CIP or inform City Code updates.
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Amendment Details – Creek Buffer
A Tier 1 recommendation of the 2015 Sustainability Master Plan is the implementation of a stream/creek/ floodplain buffer.
The intention of the buffer is to reduce erosion, preserve
habitat, increase open space, and minimize impacts from site development and increases in impervious coverage.
The development of a buffer to protect streambanks from development was identified in the Sustainability Plan as a tier 1 recommendation, intended to be implemented within 1 to 3 years.
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Benefits of Creek Buffer
Can be used as nonstructural stormwater filtering and infiltration zones;
Keeps structures out of the floodplain and provides a right-of-way for large flood events;
Streambuffers take advantage of the natural filtering characteristics of the soil to slow and filter stormwater runoff. Trees and vegetation along the stream bank stabilize it against
erosion.
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Benefits of Creek Buffer
Helps to preserve riparian ecosystems and habitats. (From iSWM Technical Manual, rev. 9/14)
Maintaining the buffer helps prevent the displacement of wildlife that is common in developing areas.
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Sustainability Master Plan – Water Resources
“(S)imply providing a buffer area adjacent to streams, creeks, and floodplains can protect water quality by allowing the ecosystem to naturally collect and treat pollutants in runoff
before they reach surface waters. Buffer areas can also reduce erosion, preserve habitat, increase open space, and reduce flooding.”
- Pg. 18
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Sustainability Master Plan – Goals and Objectives
Addition of a streambuffer ordinance would fulfill two objectives:
Manage runoff and contamination of streams and groundwater.
Conserve additional tree cover.
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Sustainability Master Plan – Built and Natural Environment
Pg. 39
The Sustainability Plan makes protecting trees and stream corridors a policy initiative with direction to consider restricting development within a minimum distance of the buffer.
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Sustainability Master Plan Water Resources Recommendations
A streambuffer ordinance is recommendation WR1 in the Water Resources section with a direction to consider codifying the use of streambuffers in the City Code.
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iSWM
The adopted Integrated Stormwater Management (iSWM) Manual assists cities in meeting TCEQ stormwater requirements, in part by preserving certain natural site features conducive to abatement.
A streambuffer is also described as a Best Management Practice in the Integrated Stormwater Management Technical Manual developed by COG and adopted by the City. It is currently a tool
that the City can implement to manage runoff and bank erosion, but streambank characteristics are not defined within City Code and there is no mechanism to encourage their use.
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iSWM
Preservation and conservation of existing stream and riparian areas within a site listed as “Integrated Site Design Practice”s in the iSWM Technical Manual.
A streambuffer is also described as a Best Management Practice in the Integrated Stormwater Management Technical Manual developed by COG and adopted by the City. It is currently a tool
that the City can implement to manage runoff and bank erosion, but streambank characteristics are not defined within City Code and there is no mechanism to encourage their use.
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Sustainability Master Plan Water Resources Recommendations
Implementing iSWM is also a Key Recommendation of the Sustainability Plan.
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Typical Creek Buffer Profile
(From iSWM Technical Manual, rev. 9/14)
iSWM defines the typical creekbuffer profile. The first 25 feet from streambank are most critical in protecting the stream, though protection further out can also provide benefits.
An
effective buffer also restricts development with in the 100 year floodplain. If the 100 FP boundaries exceed the minimum for the standard buffer, the 100 FP boundaries should be the
limit of development.
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Proposed Amendment to Ord. No. 480
Allow bufferyard credit on property boundary containing buffer or on boundaries parallel to the buffer
Allow 1 for 1 tree credit for saving native trees within the buffer
Area measured 25ft from top of bank or 50ft from the creek centerline
No disturbance within stream buffer except for uses allowed in bufferyards
A redline ordinance is provided in your packet. Affected sections of Ord. 480 are section 4, Definitions and section 42, Bufferyards.
Key components of the ordinance:
- Definition
of streambuffer as 25 feet from top of bank, 50 feet from creek centerline or limits of 100 year floodplain. No disturbance would be allowed in those areas.
- Only uses that are allowed
in manmade bufferyards in section 42 would be allowed in a streambuffer (mostly limited to primitive trails and footpaths.) Streambuffer required to be placed in a conservation easement
or made a separate deed-restricted tract in a larger development. Only clearing allowed in case of imminent threat to life or property, or in cases where an invasive species is cleared
out and replaced with native species.
- Implementation of a streambuffer would be developer option under the proposed ordinance. Incentive-based, grants Council the ability to waive
bufferyard requirements when a stream runs along a property boundary, and to allow 1 to 1 credits on new interior and bufferyard plantings (when existing trees in the buffer exceed the
required bufferyard plantings for the bufferyard which is being waived.) Streambuffer and existing trees must be catalogued in a Tree Conservation Plan. Minimum amount of tree canopy
must still be preserved based on existing coverage (landscaping ordinance 585-D is not proposed to be amended at this time.)
- For sites with a stream running diagonally or meandering
through the site, 50% bufferyard credits may be given for required bufferyards on each side or parallel to the stream. The credits would apply to width and plantings. Screening with
fence, wall, or hedge would still be required.
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STREAM ON PROPERTY BOUNDARY
Off-street parking
Building
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STREAM INTERIOR TO SITE
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Consider incentivizing or requiring use of pervious pavement
Amendment Details – Permeable Pavement
Permeable pavement has developed as an alternative to impervious surfaces which cause water to sheet flow. While permeable concrete and asphalt look extremely similar to conventional
products, they allow water to seep below the surface rather than runoff at high speed.
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Sustainability Master Plan
Use of permeable pavement is Key Recommendation WR4 in the Water Resources section of the Sustainability Plan.
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Reduces surface temperatures by absorbing more heat than impervious paving;
Reduces pooling of water during rain events
Permeable Pavement can reduce the amount of surface pollution which is typically carried by rain events within the first few minutes. It transfers these pollutants to the soil where
they are filtered before entering ground water.
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Permeable vs. Conventional Surfaces
* Installed costs accounts for associated drainage structures and base aggregate costs, but does not account for maintenance or any land value factors.
Proper installation requires soil survey, base aggregate layers which allow for stability and water storage. Initial costs may be balanced out by a reduction or elimination in the need
for on-site detention, which frees land for other uses.
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Permeable vs. Conventional Surfaces
* Installed costs accounts for associated drainage structures and base aggregate costs, but does not account for maintenance or any land value factors.
Wide range of prices reflects the range of studies, applications, intended uses and type of materials.
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Proposed Amendment to Ord. No. 480
The City utilizes pervious pavers in off-street parking areas at its DPS North facility, completed in 2015.
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Proposed Amendment to Ord. No. 480
INCENTIVIZED OPTION: Permeable Concrete and Asphalt may be used to offset stormwater utility fees.
Definition added for permeable pavement.
Permeable pavers may be approved on a case by case basis.
Soil infiltration of 0.5 in/hr or greater is required, per iSWM specifications.
Based on 8-2 City Council work session feedback, Staff was directed to develop two options: An incentivized approach to implementing permeable pavement and a required approach.
Incentivized:
stormwater utility fees assessed by calculating impervious coverage. This ordinance would allow sites using permeable pavement to reduce impervious coverage calculations by 50% for any
area with permeable pavement.
A definition would also be added which outlines minimum requirements for a surface to be considered permeable pavement.
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Proposed Amendment to Ord. No. 480
REQUIRED OPTION: 20% of all off-street parking areas required to be permeable on sites or developments that are larger than 1 acre.
Permeable pavers may be approved on a case by case basis.
Ordinance may be revisited in the future to consider adjusting percentage.
Based on 8-2 City Council work session feedback, Staff was directed to develop two options: An incentivized approach to implementing permeable pavement and an approach which makes use
of permeable pavement a requirement.
Required: All sites or portions of a development over 1 acre would be required to pave at least 20% of off street parking areas using permeable
pavement. (Based on language in the Sustainability Plan and iSWM.)
A definition would also be added with both options which outlines the minimum requirements for a surface to be considered
permeable pavement. (Engineered, maintenance plan, letter of certification at C.O.)
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Section 4 and Section 34 do not agree on number of garage sales allowed
Amendment Details – Garage Sales
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Section 4 and Section 34 do not agree on number of garage sales allowed
Amendment Details – Garage Sales
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Option 1 – Amend Section 4
GARAGE SALES – Occasional sales (garage sales and patio sales only) at retail, not to exceed two (2) three (3) in number on the same premises in any one calendar year, by a person who
does not hold himself out as engaging in, or does not habitually engage in, the business of selling such property at retail; provided that (1) the sale shall be confined to the garage
and/or patio of the premises; (2) no new merchandise acquired solely for the purpose of resale on the premises shall be sold at such occasional sale; (3) the duration of each such sale
shall not exceed three (3) consecutive calendar days; (4) a permit shall be secured at least 72 hours prior to and shall be prominently posted on such premises during such sale; (5)
the permit fee amount shall be as established by the City Council; (6) only one sign shall be permitted, not to exceed two (2) square feet in area, upon the premises where and when the
sale is taking place. All other signs relating to the sale, either on or off the premises, shall meet the requirements of all sign regulations adopted by the City.
The First option would amend Section 4 to allow three garage sales per year in accordance with Section 34, accessory uses.
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Option 2 - Amend Section 34
The Second option would amend Section 34 to allow 2 garage sales per year in accordance with Section 4.
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Proposed Amendment to Section 45 to add “RE-5” and “RE-7” in place of former “RE” district
Ord. 480-UUUU was approved in June and established the RE-5 (formerly RE) and RE-7 zoning districts. This amendment would update two instances in Section 45 that were missed with Ord.
480-UUUU.
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PZ Action
August 18, 2016; Voted 4-0 to recommend approval, noting that both options for the paving will go to Council, further noting P&Z's recommendation with respect to the number of garage
sales allowed within section 4, Definitions and section 34, Accessory Uses be two allowed per year and not three, and approving the final component of the amendment.
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Questions?
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