A D VA N C I N G G R E AT P L A C E S : N AT U R A L R E S O U R C E S A S S E S S M E N T 2 0 1 9

Chattanooga-Hamilton County
Regional Planning Agency

10.15.19

CITY OF CHATTANOOGA

NATURAL RESOURCES
ASSESSMENT
 Chattanooga City Council Staff Team
Chip Henderson Bryan Shults, Director Development Services
Jerry Mitchell Emily Wood, Principal Planner, AICP
Ken Smith John Bridger, Executive Director
Darrin Ledford Joseph Beeler, Senior Planner
Russell Gilbert Lisa Thompson, Subdivision Coordinator
Carol B. Berz Melony Collins, Graphics & Technology Specialist
Erskine Oglesby Jr. Randolph Pullen, Planning Analyst II
Anthony Byrd Winsetta Ford, Communication Design Supervisor
Demetrus Coonrod Yuen Lee, Director Research and Analysis

Chattanooga-Hamilton County Regional Planning Commission Advisory Committee

City Mayor Andy Berke, represented by Blythe Bailey Bob Geier
City Councilman Darrin Ledford Charles Adamson
Thomas Palmer Chris Mabee
Mark K. Hiatt Christy Auld
Adam Veron Donna Shepherd
Jason T. Farmer James Havron
Velma Wilson Jim Johnson
County Mayor Jim Coppinger, represented by Todd Leamon or Micah Duffey
Alan Knowles Michael Mallen
Hamilton County Commissioner Chester Bankston Mike Croxall
Y.L. Coker Phillip Clay
David Matthews Tim McDonald
Chris Mabee
Jim Parks Technical Committee
Barry Payne Ariel Soriano, Senior Engineer
Ethan Collier Charles Young, Assistant Director Land Development Office
John Bridger Clea Klagstad, Circadian Consulting, LLC
Jeremy Swilley, Development Inspector
Maria Price, Engineering Manager
Marty Hawkins, Senior Engineer
Tony Kinder, Engineering Manager
Jejal Reddy Bathi, P.E., University of Tennessee Chattanooga
 EXECUTIVE
EXECUTIVESUMMARY
SUMMARY
The City of Chattanooga is blessed with an abundance of natural Environmental Regulations, Current Zoning Process of Natural Resources
resources, including ridges, mountains, rivers, wildlife, and natural beauty. Areas, Gap Analysis, and Implementation and Action Steps.
This abundance of natural resources has become one of the many
defining characteristics of the Scenic City. Population growth and APPROACH
increased development in recent years has led to more zoning requests, RPA staff utilized the following resources to inform the recommendations
building permits, and land disturbing permits being issued in areas or sites in this Assessment:
with sensitive natural resources such as slopes and floodplains. More
particularly, these development activities neighborhoods like North
1) To understand building permit and land disturbance trends, RPA
Chattanooga and St. Elmo led citizens to contact their City Council staff analyzed the building permit and land disturbing permit data
representatives and attend public meetings voicing concerns or issues
from the Land Development Office.
with the intensity of development occurring in these natural resource
2) RPA staff utilized GIS mapping software to classify and analyze
areas.
slope and floodplain information across the City to get a better
understanding of how and where development activities were
Therefore, the Chattanooga City Council held a public hearing on impacting sensitive areas.
Tuesday, October 30, 2018, to determine the public’s issues and concerns 3) RPA staff formed an Advisory Committee consisting of residents,
and to gauge the public’s interest in developing standards or other development interests, engineers and legal experts to serve as a
regulations to address development and construction activity in natural sounding board and a forum to discuss the underlying issues and
resource areas. Following this public hearing, City Council passed opportunities for solving them.
Resolution Number 29784 on December 18, 2018, directing RPA staff to 4) RPA staff also consulted with a working technical team consisting
analyze the City’s steep slopes and floodplain challenges, compare of City engineer staff, UTC faculty, and independent engineers in
Chattanooga’s regulations with other peer cities, and to recommend the field to help with the methodology.
appropriate regulations to address the identified issues. RPA considered 5) RPA staff consulted multiple sources including Hamilton County
the following question during the assessment writing process which helped Natural Hazards Mitigation Plan, Federal Emergency
frame the recommendations, “How do we accommodate growth Management Agency, Tennessee Emergency Management
without compromising the City’s scenic assets and natural Agency, American Planning Association, Land of Sky Mountain
amenities?” Ridge and Steep Slope Protection Strategies, Conservation Tools
Steep Slope Ordinance, Knoxville and Knox County Hillside and
This Executive Summary provides a synopsis of the entire Assessment, Ridgetop Protection Plan, and Natural Resources Conservation
including the methodology, the core issues and concerns, key findings Service. These reference documents are listed in Appendix B.
from the analysis, findings from the peer review, and staff
recommendations. The remainder of the Assessment contains the This process was also shaped by the following principles:
following sections: Background, Characteristics of Steep Slopes and
Floodplains, Economic Impacts of Development and Preservation of 1. Protecting the Health, Safety, and Welfare of the City of Chattanooga
Natural Resource Areas, Existing Plans and Policies, Existing
Residents
2. Protecting the Environment lots with no stabilization or pending construction, and infill vacant lot
3. Protecting Scenic Beauty development in established neighborhoods was impacting adjacent
4. Balancing Protection with Meeting Housing Needs properties (debris/runoff).
5. Balancing Protection with Protection of Private Property Rights
3. Public Complaints
CORE ISSUES AND CONCERNS During rezoning hearings, and at the October public hearing, the
public have noted the following concerns:
Based on the information gathered from the October public hearing, and
discussions with both the Advisory Committee and Land Development
Office staff, RPA staff have identified the following as the key issues and • How proposed development concepts impact
concerns related to development in steep slopes and floodplains: slopes/floodplains
• Increase in stormwater run-off onto streets and adjacent
1. Inadequate zoning standards that address development on property during the site development process
sensitive sites. • Loss of trees/vegetation and wildlife habitat
A lack of appropriate zoning regulation standards or other tools that • Mass grading of entire site
are necessary to appropriately regulate development and construction • Loss of scenic views
activity occurring in natural resource areas has led to inconsistency in • Sites prematurely cleared without proper stabilization or
the rezoning process. While current regulations do address filling in timely start of construction
the floodplain, they do not address excessive site clearing, grading or
limiting development in natural resource areas. In some instances, KEY FINDINGS FROM DATA/POLICY ANALYSIS
current regulations (such as setbacks and right-of-way standards) can Development trends were analyzed from a ten year period (2009-2018)
increase impacts to these sensitive sites. using building permit, land disturbing permit, and zoning case data to see
where development or construction activity is occurring in relation to
Without zoning standards, RPA staff is reacting to rezoning requests existing natural resource areas.
by creating conditions “on the fly” to provide protections of natural
resources. The Land Development Office (LDO) has to track What does the Data Indicate?
conditions on the back end of development review as opposed to a The following is a brief overall summary of the development trends from
codified regulation or development standard. This results in less 2009 thru 2018.
predictability and consistency in defining appropriate site design and
best management practices for development or construction activity in • Acreage of vacant land with slopes 25% or greater accounts for
natural resource areas. 54% of the vacant acres of land.
• The majority of building permits issued for construction activity
2. Site Review/Enforcement are located on sites in the 0-15% slope class; however, the
Prior permitting procedures did not clearly indicate the timing for slope permits in the over 25% slope class increased by 45% during the
stabilization or enforce sufficient penalties to ensure good site 10-year period, while overall permits increased by only 6%.
development practices. A site tour with the Advisory Committee • The majority of the land disturbing permits issued for construction
indicated the following site management issues: premature clearing of activity are located in the 0-15% slope class; however, the
 permits in the over 25% slope class increased by 91% during the Most ordinances contain regulations that permit narrower road standards
10- year period. Overall permits increased by 83%. and reduced setbacks to limit disturbance on slopes. Heights of buildings
• Seventy-percent (70%) of the zoning requests and special are also reduced to a height of not less than the average height of the tree
permits for Residential Planned Unit Developments are located canopy. Reductions in density and limitations on building footprints were
in natural resource areas. used to limit disturbance. Standards limiting grading, clearing, and
• There are areas in the City that are at high risk for soil erodibility disturbance as it relates to slope of the land are used in most of the
based on the “K” factor. These areas include steep slope areas ordinances reviewed.
on Missionary Ridge, Lookout Mountain, and Big Ridge. High soil
erodibility can also be found along the floodplain areas. A recent How did Chattanooga Regulations Compare to Peer Jurisdictions?
example of this issue is the slope failure along Lake Resort Drive The analysis indicates the City lacks certain standards or tools in the
that collapsed earlier this year. The repairs will cost the City zoning or subdivision regulations that could be effective at addressing
approximately 5 to 11 million dollars. public concerns and issues and provides suggestions on how to alleviate
• Over 80% of the floodplain has been developed. This heightens the concerns based on best management practices from the peer review
the concerns for protecting the remaining floodplain areas. jurisdictions.
• The number of land disturbing and building permits issued for
sites within the floodplain have declined during the 10-year Zoning and Subdivision Regulations
period. RPA grouped the natural resources
• There has been high risk and standards found in the zoning and
documented property damage subdivision regulations of the peer
associated with major flood events review jurisdictions into a total of 22
through the issuance of insurance $5,739,568 IN 2018 overall requirement categories. Of the
claims. 22 requirement categories, the City of
Chattanooga had only 2 similar
PEER REVIEW/GAPS ANALYSIS regulations of the peer review jurisdictions.
Many jurisdictions have adopted natural resource protection ordinances
because of the unique challenges topography and the floodplain have for Stormwater and Land Disturbance Permits
the development of land. In investigating these peer jurisdictions, RPA RPA grouped the standards and regulations into a total of 29 overall
limited the review to jurisdictions in the southeast that are very similar to requirement categories. Of the 29 requirement categories, the City of
the City of Chattanooga. The jurisdictions included Knoxville, TN, Chattanooga had 19 similar regulations of the peer review jurisdictions.
Nashville, TN, Williamson County, TN, Asheville, NC, Durham, NC, and
Huntsville, AL. RECOMMENDATION
Based on the analysis of the data trends, public comments received
Many of the ordinances and regulations RPA reviewed had common including land use plan recommendations, comments from the Advisory
approaches for reducing the impact of development and construction and Technical Committee, and best management practices, RPA is
activity on slopes and floodplains. These approaches all had a goal of recommending for City Council’s consideration the adoption of a Natural
limiting disturbance in these sensitive areas. Resource Protection Ordinance that accommodates growth and at the
same time offers protection of the City’s or pose safety concerns for less mobile residents such as a nursing
scenic assets and natural amenities. The home.
ordinance includes changes to codes that
add more flexibility (density bonuses) and 3. Limitations on Clearing, Grading or Disturbance
modifications to existing standards that Establish restrictions that limit the amount of clearing, grading, and
currently make it more difficult to disturbance permitted on a site during construction. For example, for
minimize the impacts of development on sites with slopes of 15% to 25% the amount of disturbance permitted
these sites. The recommendations also in the sloped area could be limited to no more than 50% clearing,
include new standards that limit grading, clearing, and filling of slopes and grading, or disturbance. For sites with slopes of 25% or greater the
floodplains to protect Chattanooga’s scenic natural landscapes. amount of disturbance permitted in the sloped areas could be limited
to no more than 25% of clearing, grading, or disturbance.
The Natural Resource Protection Ordinance would apply to all properties
meeting the criteria city-wide. The ordinance will help fulfill the goals of 4. Tree Canopy Protection Standards
protecting the City’s natural resources as identified in the adopted Explore options of requiring a certain percentage of existing tree
Comprehensive Plan Update 2030 and Land Use Plans. An Ordinance is canopy on the development site to be retained and protected during
enforceable, consistent, and will address the gaps and public concerns construction for sensitive natural resource sites. Existing tree canopy
identified through this assessment. retained could be used as credits towards any open space or
landscape yard requirements.
Recommended Standards in the Natural Resources Ordinance
5. Limit Amount of Impervious Surface
RPA is recommending the following amendments and standards that
Establish standards or regulations limiting or reducing the amount of
regulate the following topics. Please note that any reference to a specific
impervious surfaces for non–residential uses such as minimizing
quantitative standard is for illustrative purposes only.
parking space stall dimensions, required number of compact car stalls,
using porous surfaces, encourage shared parking, and encourage
1. Definition of Steep Slope
structured parking decks.
Define a percentage grade of a “steep slope” that will serve as a
baseline for the Natural Resources Ordinance. For illustration For residential uses limiting the amount of driveway and building
purposes only, slopes could be categorized as “Moderate Slopes: 15- footprint to a certain percentage of the total lot area.
25%” and “Very Steep Slopes: 25% or greater.”
6. Establish a “Zero Net Increase” in Floodplain Fill
2. Land Use Restrictions
Establish standards that require compensatory storage to off-set fill.
Establish a special permit process for intensive land use activities
This is often referred to as a 1:1 fill ratio. The basic concept is an
(such as hospitals, public assembly uses, and intensive non-
equal volume of fill shall be removed for a site to compensate for the
residential uses) that may occur in high hazard areas such as
same volume of fill that is placed in the floodplain.
documented slope hazard areas or flood-prone areas. The main
objective is to ensure the use would not present accessibility issues
7. Density Bonus OTHER RECOMMENDED TOOLS
Establish a density bonus in residential density if a certain percentage As part of this assessment RPA determined that other regulations or tools
of a site or lots with natural resources is preserved and set aside from will need to be amended or created and are briefly described below.
development. For example, Asheville, North Carolina permits a
residential density bonus of 30% if 30% to 40% of the site with natural City of Chattanooga Subdivision Regulations
resources is preserved. The density bonus increases as the amount RPA is recommending amendments to the Chattanooga Subdivision
of land preserved increases up to a maximum of a 60% density bonus. Regulations as additional tools of protection of our scenic assets and
natural amenities.
For non-residential uses the density bonus could be an increase in
building height or reduced parking requirements. 1. Road Reductions on Hillsides
Allow an opportunity in the subdivision regulations to reduce the
8. Flexibility in Required Setbacks
required minimum right-of-way in hillsides or sloped areas to reduce
Establish a staff approval process for reductions in front and rear
the amount of impervious surface and land clearing necessary for the
setbacks if a portion of the site containing natural resources is
construction of streets. This will require coordination and discussions
preserved and site grading is limited.
with other partners such as Chattanooga Department of
Transportation (CDOT) and the Fire Marshall’s Office.
9. Lots of Record
Existing lots legally recorded prior to the adoption of the Natural
Resources Ordinance should be analyzed more thoroughly to 2. Critical Lot
determine their requirements of the Natural Resource Ordinance and Lots that contain steep slopes, soil conditions/high erodibility, and
if there would be any unintended consequences or undue hardship floodplains should be identified on the subdivision plat as a critical lot
created for lots of records by being required to comply with the Natural and should be evaluated by a geotechnical engineer/report as to the
Resources Ordinance. However, lots of record could be eligible for feasibility of construction and methods of construction that will address
reduced setbacks if the natural resource area on the site is preserved the stabilization and stormwater run-off associated with a critical lot.
and no grading occurs in this area. Special standards could be
developed that factor in different home construction techniques (such 3. Slope Map
as slab construction versus pier construction). Additional flexibility will Staff is recommending that slope maps be provided by applicants
be needed to address the unique site conditions for each lot of record. during permit review showing the delineation of existing slope
The overall objective is to establish some basic parameters on categories. Slope maps are available through a free website from
clearing and grading on a lot of record. Hamilton County GIS.

10. Planned Unit Development (PUD) 4. Site Assessment Map

Amend the PUD tool with new and up-to-date standards and criteria Staff is recommending a site assessment map be provided by
that can be used as a tool to protect natural resource areas and applicants during permit review that shows the approximate location
provide incentives for developers such as an increase in the permitted and indication of size and condition of all natural hazards and sensitive
density in exchange for preserving sensitive areas or providing environmental features found within boundaries of the proposed
useable open space for residents.
 subdivision. Such items include sinkholes, soil classifications, springs, concerns and issues voiced by the public. RPA has contacted the Land
wetlands, bluffs, streams, etc. Development Office, and they are aware of these recommendations and
are supportive of the following:
5. Conservation Based Design Subdivision Standards
Create a conservation based design subdivision tool that provides 1. Landscaping and Material Facing of Retaining Walls
clear standards for natural resource protection. This tool will establish Explore options of requiring landscaping or material facing for
regulations that require a certain percentage of the area to be landscape retaining walls of a certain size.
permanently protected as open space. In return the developer is
provided with flexibility in required minimum lot size, setbacks, lot 2. Timing of Retaining Wall Construction
frontage, and street widths. Density bonuses could also be part of the Explore options of requiring that retaining walls be constructed onsite
requirements for conservation based design subdivisions. prior to the start of construction of the building or structure.

6. R-1 Open Space Option 3. Limitations on the Amount of Land Disturbance of Grading
The R-1 Open Space Option was adopted by City Council in 1995 and Permitted at One Time
has rarely been utilized. This tool should be evaluated to determine Explore options of limiting the amount of clearing, grading, or
why it is not being used and if possible amendments are required. disturbance permitted at any one time on a site. For example, a
maximum of 10 acres of clearing, grading, and disturbance should be
This option may need to be removed from the Chattanooga Zoning
permitted only with the 10 acres being stabilized and revegetated prior
Regulations as this is not a zoning classification; it is a subdivision
to applying for additional clearing, grading, or disturbance for other
design option that provides alternative design standards for areas on the same development site.
development of a single-family residential subdivision.
4. Security Bond for Revegetation/Stabilization
7. Promote more opportunities for infill development in less
sensitive areas Explore options of requiring a security bond or letter of credit for sites
RPA is in the process of creating areas plans for the City of of a certain size to provide the city required revegetation and
Chattanooga. One goal or policy of the area plans is to encourage stabilization.
infill development in established neighborhoods and supports various
housing forms and types to meet the housing demand and 5. Slope Stability Certifications
opportunities to provide affordable housing for the residents of Explore option of requiring a geo-technical engineering report or
Chattanooga. Opportunities to promote more housing infill options certificate for slopes sites that the site or slope is free of failures, and
should be identified and established with each area plan. that temporary or permanent ground cover is provided.

Improvements to Permitting Process/Code 6. Site Plan Review or Geo-Technical Report for Critical Lots
Based on the peer view, Gaps Analysis, and best management practices Explore option of requiring detailed site plans for lots identified as
from city staff and stakeholders, there may be additional opportunities for critical lots. A critical lot would be a lot with slopes, floodplains, and
the Land Development Office to explore options for possible amendments high soil erodibility. Additional measures should be required by
to Municipal Code Section 31, Stormwater Management to address applicants such as a geotechnical engineer/report as to the feasibility
 of construction and methods of construction that will address the SUMMARY
stabilization and stormwater run-off associated with a critical lot. RPA’s recommendations are not intended to limit or prohibit growth and
development on steep slopes or floodplains. The recommended Natural
7. Timing of Land Disturbing Permit and Start of Construction Resource Ordinance is meant to provide standards that allow for the
Explore options of requiring that the start or beginning of building appropriate and wise development of sites containing slopes and
construction be noted on the application for a land disturbing permit, floodplains.
and the beginning of building construction to begin within so many
days after permanent clearing, grading, and disturbance has ended. As noted earlier in this summary, 54% of the remaining vacant land is on
steep slopes, and permit trends have indicated that development activities
8. Soil Erosion Modeling will continue to increase in these sensitive areas as the City grows.
Require applicants to submit RUSLE soil erosion loss calculations for Currently Chattanooga only regulates two of twenty-two common zoning
construction sites prior to receiving a land disturbing permit. The standards found among the six peer cities. The increase in citizen
Revised Universal Soil Loss Equation (RUSLE) is the most widely concerns and complaints about loss of tree cover, mass grading,
applied model in the U.S. The RUSLE model measures variables stormwater run-off and impacts to the City’s scenic character has served
such as annual soil loss due, rainfall impact, soil erodibility, and as an indicator that the current standards for sensitive site development
topography derived from slope length and slope gradient in order to are inadequate. It is also important to note that many of the current
understand soil loss rates and erosion. Understanding soil types and standards actually make the problem worse by offering limited flexibility in
erodibility can help the City staff to estimate annual soil loss to water setbacks, right-of-way widths, and density incentives to promote
erosion and understand how the construction phase of land protection of sensitive areas.
development impacts water quality. At the time of writing this
Assessment, the Land Development Office is considering amending As stated earlier in this Executive Summary, during the creation of this
their 2017 enforcement policy to require applicants to submit RUSLE assessment RPA would adhere to five key values or principles during this
calculations with permit applications. assessment as well as suggesting recommendations.
1. Protecting the Health, Safety and Welfare of the City of Chattanooga
9. Stormwater Requirements Resident
Consider including additional peak flow stormwater requirements and 2. Protecting the Environment
3. Protecting Scenic Beauty
stormwater detention for steep sites during post-construction 2, 5,
4. Balancing Protection with Meeting Housing Needs
10, and 25-year storm events. Peak flow rates for disturbed,
5. Balancing Protection with Protection of Private Property Rights
unvegetated conditions must also be considered by the design
engineer, with the greater flowrate of the two conditions (disturbed or
To address the identified issues, and to balance the key values listed
post-developed) governing.
above, RPA has provided a list of recommended changes that
accomplishes the following:
• Better definitions of the sensitive resources to be protected
• Clear standards for how these sites are developed through
grading, clearing and filling limits
 • Density bonuses for leaving sensitive areas undisturbed
• New zoning/subdivision tools that provide added flexibility for
setbacks, and right-of-way widths
• Improved land disturbing permit standards to provide more “due
diligence” safeguards when developing in sensitive areas

The number of recommended standards and changes in this report is

substantial. Nonetheless, staff advises that these standards are needed
based on our assessment of the issues, review of best planning practices
and other City ordinances. The Zoning Ordinance has not received a
comprehensive update in over twenty years which may partially explain
the lack of standards and the low score in the Gaps Analysis. Given the
amount of changes proposed, staff would recommend a “grace period” for
any new ordinances to provide an opportunity for the local market to adjust
to these new requirements. While these changes are substantial, they are
not, in staff’s opinion, impractical given that they are already in practice
among the six peer Cities studied (Knoxville, Nashville, Williamson
County, Asheville, Durham, and Huntsville). RPA staff is ready to begin
developing the specific ordinance tools and standards, once City Council
has provided direction to staff concerning the recommended approaches.