[1]
Editor's note-Internal cross-references were corrected without
notation throughout section 14, Integrated Stormwater Management.
This Criteria Manual for Site Development and Construction is
adopted and becomes effective on September 1, 2012.
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Purpose and Limitations of Manual
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This manual is intended to provide a guideline for the most
commonly encountered stormwater or flood control designs in the City
of Azle. Also, it’s a guide for watershed master plans and for
design of remedial measures for existing facilities. This manual was
developed for users with knowledge and experience in the applications
of standard engineering principles and practices of stormwater design
and management. There will be situations not completely addressed
or covered by this manual. Any variations from the practices established
in this manual must have the expressed written approval of the Storm
Water Manager. Close coordination with city staff is recommended and
encouraged during the planning, design and construction of all stormwater
facilities.
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Goals and Objectives for Stormwater Management
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A proper understanding of the City’s adopted goals and
objectives for stormwater management, as summarized in Section 14.5.0,
is essential for the proper application of this Manual.
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Contact Information
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Information on Azle’s Stormwater management program and
policies can be obtained at: 817-444-4511 or at the website: www.cityofazle.org. For
additional information on the iSWM regional manual and program, contact
the North Central Texas Council of Governments (NCTCOG) at 817-695-9191
or at the website http://iSWM.nctcog.org/.
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Abbreviations and Definitions
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For convenience, two terms which are used frequently throughout
this manual are abbreviated:
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CITY OF AZLE - City of Azle
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SWM - Storm Water Manager
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Several stormwater and development terms are used in this manual
which have unique or special meanings. They are defined below:
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1.
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Adequate Outfall - Outfall
that does not create adverse flooding or erosion conditions downstream
and is in all cases subject to the approval of the Storm Water Manager.
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2.
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BMP or Best Management Practice - A physical, chemical, structural, or managerial practice or device
that prevents, reduces, or treats the pollution of stormwater, or
reduces or treats erosion, or minimizes runoff.
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3.
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Development - A contiguous
tract of land (or a tract of land separated only by roadway and/or
drainage right-of-way or easements) to be considered as a single development
for purposes of this policy. Development - A contiguous tract of land
(or a tract of land separated only by roadway and/or drainage rights-of-way
or easements) to be considered as a single development for purposes
of this policy, if the tract has one or more of the following characteristics:
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Included in a single Concept Plan submitted to the City of Azle,
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Included in a single Preliminary Plat submitted to the City
of Azle,
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Is comprised of contiguous land (or land separated only by a
roadway and/or drainage rights-of-way or easements) under the same
root ownership,
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Is encumbered by a single Master Drainage Study or Plan,
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Is encumbered by a single Developer’s Agreement, TIF,
360 Agreement or other public/private partnership agreement,
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Is overlaid by a common Homeowner’s or Property Owner’s
Association (HOA, POA), or
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Is owned or managed by a common Master Developer.
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4.
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Drainage Study - Studies
of the proposed development and drainage areas, including a downstream
assessment will accompany the conceptual, preliminary, and final site
plans and will include the necessary hydrologic and hydraulic analysis
to clearly demonstrate that the limits of the Zone of Influence have
been identified.
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5.
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Downstream Assessment - Downstream assessment of properties that could be impacted by
the development.
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6.
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Engineer or Engineer of Record - The person authorized to practice engineering in Texas who is
responsible for preparing engineering plans for a development.
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7.
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Fully Developed Conditions - For watershed hydrology, fully developed conditions include all
existing developed areas and all existing undeveloped areas [and]
shall reflect anticipated future land use designated by zoning classification.
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8.
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Grading Permit - The
approval by the City of Azle to proceed with the disturbance of 0.1
acres or more, after review and approval of iSWM, Floodplain, or other
City regulations.
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9.
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iSWM Construction Plan - A plan and notes indicating the installation and maintenance of
BMPs and application of pollution prevention procedures used to control
erosion, sediment, construction materials, and waste during the construction
phase of improvements in conformance with the criteria contained in
this Manual.
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10.
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iSWM Plan or iSWM Site Plan - A stormwater management plan that conforms to the criteria contained
in this Manual.
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11.
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Maintenance Plan or Operations and Maintenance
Plan - A plan prepared in accordance with this
Manual for the purpose of describing maintenance and operational requirements
of a structural BMP and interchangeably used with the “City
of Azle Stormwater Facility Maintenance Plan”
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12.
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Natural Creeks - Those
drainageways that are generally unimproved, that often exhibit a meandering
course, and which are not proposed to be improved to City standards
for earthen channels.
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13.
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Private Water - Runoff
water which generated on private property and flowing within the property
or from one property to another. Drainage easements and drainage facilities
which contain only private water shall not be maintained by the City.
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14.
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Public Water - The concentration
of surface water flowing through or from public land or right-of-way.
Public water must be contained within a dedicated right-of-way, floodplain
or drainage easement.
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15.
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Stormwater Fee Credits - An incentive provided by the City of Azle to encourage the voluntary
use of BMPs which improve stormwater management.
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16.
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Stormwater Facility Maintenance Agreement
or Maintenance Agreement - A legal agreement
between the City of Azle and a property owner for perpetual maintenance
of a structural BMP.
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17.
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Stormwater Pollution Prevention Plan or SWPPP - The site design, operations, and inspections plan
required by the Environmental Protection Agency (EPA) and the Texas
Council on Environmental Quality (TCEQ) for the control of erosion
and sediment during construction. The iSWM Construction Plan covers
much of the site design requirements required by the SWPPP.
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18.
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Zone of Influence -
A “zone of influence” from a proposed development extends
to a point downstream where the discharge from a proposed development
no longer has a significant impact upon the receiving stream or storm
drainage system.
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Overview of the iSWM Program
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The iSWM Program for Construction and Development is a cooperative
initiative that assists municipalities and counties to achieve their
goals of water quality protection, streambank protection, and flood
mitigation, while also helping communities meet their construction
and post-construction obligations under state stormwater permits.
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Development and redevelopment by their nature increase the amount
of imperviousness in our surrounding environment. This increased imperviousness
translates into loss of natural areas, more sources for pollution
in runoff, and heightened flooding risks. To help mitigate these impacts,
more than 60 local governments are cooperating to proactively create
sound stormwater management guidance for the region through the integrated
Stormwater Management (iSWM) Program.
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The iSWM Program is comprised of four types of documentation
and tools as shown in Figure 1. These are used to complement each
other and to support the development process.
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Figure 1: iSWM Program Support Documents and Tools
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The four parts of iSWM are:
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iSWM Criteria Manual - This document
provides a description of the development process, the iSWM focus
areas and locally adopted design criteria allowing municipalities
a flexible approach to apply at a local level.
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iSWM Technical Manual - This set of document
provides technical guidance including equations, descriptions of methods,
fact sheets, etc. necessary for design.
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iSWM Tools - This includes web-served
training guides, examples, design tools, etc. that could be useful
during design.
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iSWM Program Guidance - This includes
reference documents that guide programmatic planning rather than technical
design.
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(Ordinance 2012-10 adopted 8/21/12)
