(A) 
See Article 5, Division 1 in this Chapter 3 for the required stormwater practices for new development and redevelopment.
(B) 
Unless otherwise provided in this Code, all stormwater management practices, techniques and facilities shall be conform to the standards and requirements contained in Article XII (Stormwater Quality) of Chapter 31 of the City Code, with the City’s Technical Standards, and with any other applicable regulations in the City Code and this GDC.
(Ordinance 6773 adopted 5/19/15)
(A) 
General.
No person shall alter, change, modify, excavate or fill any lot, subdivision or development in a manner that causes a material adverse impact from surface runoff or stormwater to adjoining property. An appropriate plan submittal and permit from the Building Inspections Department shall be required for any land disturbing activity exceeding 5,000 square feet up to one (1) acre, or changing the grade elevation by cut or fill in excess of 1' from existing grade. Disturbance of over one acre shall require Site Engineering Drawings, as set forth in Section 3.95 of Chapter 3 of this GDC. Any unpermitted fill piles shall be removed or spread to within allowed grades within thirty (30) days of the initial pile being placed on the property. The Director of Engineering or the Building Official may require submission of proof of compliance with the provisions of this Division, certified by an engineer who is licensed in the State of Texas.
(B) 
Improvements Required.
Grading and drainage improvements must conform with the applicable provisions of this Division and with the City’s Technical Standards. Grading and drainage plans submitted to the Engineering Department shall be prepared under the direction of, and shall be sealed by, a professional engineer who is licensed in the State of Texas.
(C) 
Plan Submittal.
Grading and drainage plans for all developments shall be provided as part of the Site Engineering Drawings unless no Site Permit is required, in which case grading and drainage plans shall be submitted with the Building Permit submittal documents. If no Building Permit is required, mass grading plans shall be submitted for a Site Permit to the Engineering Department.
(Ordinance 6773 adopted 5/19/15; Ordinance 7055, sec. 25, adopted 5/7/19)
(A) 
Purpose.
The City acknowledges the wide diversity of existing creeks and drainageways throughout the City and states its intention that overall drainage patterns and features shall be disrupted as little as possible in the process of development, provided that a development must provide adequate drainage through a stable, easily maintainable manner.
(B) 
Floodplain Development Requirements.
All development proposed adjacent to or within the 100-year floodplain shall conform with the City’s Flood Damage Prevention Ordinance (Article VII of Chapter 31 of the City Code).
(C) 
Designated on Plat.
Any dedications and easements required by this Chapter 3 shall be designated on the Preliminary Plat and Final Plat.
(1) 
Final Plat Inscription.
Every Final Plat of a subdivision which contains a drainageway as regulated by this Chapter 3 shall contain special language as set forth in the City’s Technical Standards Manual, as amended.
(2) 
Notice of Inscription to Grantee.
In addition, the developer shall include with or in the deed of each lot of the subdivision which abuts or contains a drainageway, a notice of the foregoing language sufficient to inform the grantee of the deed of the requirement contained within the language.
(D) 
Creeks and Natural Drainageways.
The following provisions shall apply to all proposed development in relation to creeks.
(1) 
All creeks that have designated floodplains and Flood Insurance Study (F.I.S.) floodways, and any other natural drainage course, as identified by the most current Flood Insurance Rate Maps (FIRM) or by the Director of Engineering, may be left in a natural state, if so approved by the Director of Engineering.
(a) 
In order for the Director of Engineering to approve a creek to be left in its natural state, the natural channel along with the encompassing drainage easement shall be of sufficient width and depth to carry the 100-year storm, plus one foot of freeboard and ten-foot accessway on both sides of the channel. Disturbance of a natural channel is prohibited except that prior to acceptance by the City, the developer shall perform general maintenance such as clearing underbrush, debris dam removal, litter pick-up, and the removal of other undesirable items, as directed by the Director of Engineering.
(b) 
In these cases, the entire 100-year floodplain shall be platted out separately as a drainage easement, and the developer shall provide a means of acceptable access for city stormwater personnel. An erosion hazard setback (per the Technical Standards Manual) may also be included in the drainage easement dedication. The drainage easement shall be dedicated on the Final Plat as a separate lot to be owned and maintained by a Homeowners’ or Property Owners’ Association (as applicable for residential or nonresidential). At no time shall any portion of the 100-year floodplain exist or be within any single-family or two-family residential lot unless the lot is not within a Homeowners or Property Owners Association or a subdivision containing four or more lots, unless it is contained in a subdivision consisting of fewer than four lots. A minimum ten-foot wide accessway shall be provided along each side of the drainageway and included in the drainage easement with a traverse slope not to exceed ten percent, all in accordance with the Technical Standards Manual.
i. 
Such access shall be subject to review and approval by the Director of Engineering, and streets or alleys may be required between dedicated properties and adjacent development.
ii. 
Other undeveloped floodplain may also be dedicated as a drainage easement, pursuant to Subsection (b) above, at the time of platting.
(2) 
Responsibility for drainage maintenance shall be set forth in the drainage easement.
(3) 
So as to meet the stability and maintenance provisions in Subsection A above, the City may require improvements to creek or creek banks, in accordance with the Technical Standards, before issuance of a Letter of Final Acceptance in accordance with Section 3.111 of this Chapter 3.
(4) 
In order to negate or mitigate the need to obtain flood insurance, all portions of residential lots shall be removed from designated floodplains in accordance with the Technical Standards Manual. In all cases, the developer shall adhere to the requirements set forth in the City Code regarding flood damage prevention, and shall furnish engineering plans prepared by a professional engineer who is licensed in the State of Texas to the Director of Engineering for review and approval.
(5) 
The following provisions shall apply to all proposed development within the Rowlett and Spring Creek 100-year floodplains, as more particularly described on the Albert H. Halff Associates, Inc., November 1988, Rowlett and Spring Creek Flood Plain Management Study:
(a) 
Base flood elevations (BFE) for the 100-year flood event that reflect ultimate development land use throughout the watershed shall be used for design and planning of floodplain development.
(b) 
Development within the floodplain shall be permitted only if it can be demonstrated that there will be no rise in the base flood elevation.
(c) 
Fill volumes shall be balanced (+/- 15%) by excavation volumes to preserve overall valley storage within the floodplain. Areas excavated shall be landscaped to restore a natural cover.
(d) 
The bed and banks of Rowlett and Spring Creeks shall be left in a natural state to control erosive velocities, prevent excessive downstream discharges, and preserve the natural effect of the stream. Exceptions are permitted for major bridge crossings, public welfare, and safety.
(e) 
Increases to existing average velocities shall be allowed to a maximum average velocity of no greater than six feet per second.
(f) 
Significant stands of trees and other environmental features within the floodplain shall be preserved.
(6) 
All lots adjacent to a creek or drainageway shall have minimum finished floor elevations defined on the subdivision plat a minimum of two feet above the FEMA F.I.S. one-hundred-year water surface elevation. Where available, the fully developed watershed water surface elevation shall be used to establish minimum finished floor elevations.
(7) 
Paved stormwater access driveways with removable bollards shall be provided from a public street right-of-way to drainage easements incorporating creeks or drainageways as directed by the Director of Engineering.
(E) 
All development shall comply with Article VII (Flood Damage Prevention) of Chapter 31 of the City Code. It shall be the responsibility of the developer to obtain a Conditional Letter of Map Revision (CLOMR) issued by the Federal Emergency Management Agency (FEMA) prior to approval of Site Engineering Drawings (and subsequent issuance of a Site Permit) and a Letter of Map Revision (LOMR) prior to issuance of a Letter of Final Acceptance in accordance with Section 3.111 of this Chapter 3.
(F) 
Upon completion and a Letter of Final Acceptance (Section 3.111 of this Chapter 3) being issued for any drainageway channel improvements as set forth within this Section 3.86 of this Division 8, the property owner on whose property the channel improvements lie, or whose property directly abuts such channel improvements, shall be responsible for necessary mowing, irrigation, weeding, litter pick-up, fertilizing, and such other maintenance as is required to maintain a healthy stand of grass or other groundcover.
(G) 
No obstruction to the flow of stormwater runoff shall be permitted.
(H) 
Additional Studies.
Upon request by the City, the property owner shall submit additional studies, including but not limited to the following, as deemed appropriate and necessary by the City, as part of the Preliminary Plat (if applicable) or Final Plat submittal requirements. These studies shall be considered during review and approval of the Preliminary or Final Plat, as applicable.
(1) 
Wetland Delineation and Waters of the U.S. Study;
(2) 
Erosion Hazard Setback Study;
(3) 
Storm Drainage Study;
(4) 
Flood Study; and
(5) 
Downstream Assessment Study.
(Ordinance 6773 adopted 5/19/15; Ordinance 7055, sec. 26, adopted 5/7/19; Ordinance 7107, sec. 48, adopted 12/3/19)
(A) 
Erosion Control.
Erosion control shall comply with the City’s Technical Standards, as amended.
(B) 
Requirement.
Underground storm sewer systems are required, as defined in the Technical Standards, to prevent excessive stormwater runoff from entering the public street or rights-of-way or private streets.
(C) 
Public underground storm sewer systems shall be contained in the public street right-of-way or within a drainage easement that is in accordance with the City’s Technical Standards Manual. At low points on grade, a concrete-lined positive overflow path shall be provided. The positive overflow path shall be contained in a drainage easement of sufficient width to convey the 100-year storm runoff.
(D) 
Calculation of Runoff.
The calculation of stormwater runoff shall comply with the Technical Standards. Stormwater runoff calculations shall be made anticipating a fully developed watershed, prepared and sealed by a professional engineer licensed in Texas, and submitted for review and approval by the Director of Engineering. The Comprehensive Plan, existing land use, and zoning maps shall be used to determine fully developed conditions. The Director of Engineering reserves the right to review the determination of fully developed conditions and may require revisions.
(E) 
Detention.
If stormwater runoff from a proposed development exceeds the capacity of the existing downstream system, detention of stormwater runoff in a manner prescribed by Section 3.89 of this Division 8 shall be provided for the excess runoff. Easement and maintenance responsibilities for the detention system shall be inscribed on the Preliminary Plat and Final Plat.
(F) 
Easements.
Drainage easements shall be dedicated for public drainage features in accordance with requirements of this GDC. Drainage easements and features shall be included as a portion of buildable (such as habitable structure) lot(s) and not as a separate self-standing lot unless specifically authorized by the Director of Engineering. If a large development-related feature is authorized on a separate lot, a Homeowners’ Association is required to assume maintenance responsibilities for the feature(s). Storm drainage easements shall be located along side property lines, and such easements shall be contained fully on one lot or tract, and shall not be split across the property line between two lots or tracts.
(G) 
Minimum Finished Floor Elevations.
The Director of Engineering may require minimum finished floor elevations (FFEs) to provide flood protection on certain lots within a development. The FFEs shall be shown on the Final Plat. These elevations shall incorporate the most current floodplain management criteria or other criteria as necessary to avoid damages. FFEs shall be two feet above the fully developed 100-year water surface elevation where an FFE is associated with a natural major creek or open channel. When an FFE is necessitated by situations other than a natural major creek or open channel, the FFE shall be set by the developer’s engineer and shall be subject to the approval of the City.
(H) 
Off-Site Drainage.
When a proposed development requires off-site grading where stormwater runoff has been collected or concentrated, it shall not be allowed to drain onto adjacent property except into existing major creeks, channels, storm sewers or streets unless a notarized letter of permission is obtained from the owner of the property onto which the drainage will drain. The letter shall state that the permission shall bind the owner of the affected property and shall be a covenant running with the land. It shall also refer to the plans for the improvements creating the need for the permission. The letter shall be filed for record with the applicable county.
(I) 
Definitions.
Unless a provision explicitly states otherwise, the following terms and phrases, as used in this section, shall have the following meanings:
(1) 
“Amenity pond”
means a permanent pool of a pre-determined volume of stormwater kept or maintained purely for aesthetic purposes and that is not designed to provide additional capacity for the temporary storage of stormwater required for detention.
(2) 
“Capacity”
means the maximum stormwater rate allowed in any portion of the MS4 that will not result in a surcharge of the system, or, as determined by the managing director, the maximum stormwater rate that can be allowed in any portion of the MS4.
(3) 
“Development”
means any manmade change to real property, whether previously improved or unimproved, including, without limitation, filling, grading, paving, the installation of infrastructure such as water lines, storm sewers or sanitary sewers, or the construction of buildings or other structures.
(4) 
“Discharge”
means the addition or introduction of stormwater into the MS4 or into waters of the United States.
(5) 
“Detention”
means the temporary storage of stormwater to be released at a pre-determined and controlled rate.
(6) 
“Extended dry detention facility”
means a detention basin constructed in a manner so as to retain stormwater for a time sufficient for sediments and particulate pollutants to settle and designed so that no stormwater is intended to remain in the basin after the discharge is complete.
(7) 
“Facility” or “facilities”
means a detention, retention, or other stormwater storage or handling measure as described in this section and may, depending on the context in which the term is used, include an amenity pond.
(8) 
“Managing Director”
means the Managing Director of Engineering, Transportation, Streets, and Stormwater, or a designee of that person.
(9) 
“Municipal separate storm sewer system” or “MS4”
means the system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, channels, or storm drains) owned and operated by the City and designed or used for collecting or conveying stormwater, and which is not used for collecting or conveying sanitary sewage.
(10) 
“One-hundred-year storm”
means a storm event having a one-percent chance of occurring in any given year.
(11) 
“Retention facility”
is a facility that provides a permanent pool of a pre-determined volume of stormwater and that is designed to provide additional capacity for the temporary storage of stormwater that may be required for detention purposes.
(12) 
“Stabilized cover”
means a uniform perennial vegetative cover established and maintained with a density of 70% or greater, or an approved equivalent stabilization measure (such as rip-rap, gabions, etc.).”
(Ordinance 6773 adopted 5/19/15; Ordinance 7055, sec. 27, adopted 5/7/19)
The entire cost of the design and construction of storm sewers, drainage systems, or floodplain alterations within or abutting a subdivision shall be borne by the developer. This shall include all necessary off-site storm sewer extensions necessary to achieve free outfall flow including, but not limited to, easement acquisition.
(Ordinance 6773 adopted 5/19/15)
(A) 
Purpose.
The purpose of this Section is:
(1) 
To protect, maintain, and enhance the public health, safety, and general welfare by establishing minimum requirements and procedures to control the adverse effects of increased stormwater runoff associated with land development within the City.
(2) 
To minimize damage to public and private property, reduce flooding, ensure a functional drainage system, and reduce land and channel erosion.
(3) 
To provide minimum construction standards for detention and retention facilities and amenity ponds and to facilitate long-term care and the function of those structures by establishing maintenance responsibilities.
(4) 
To assist in the attainment and maintenance of stormwater quality standards.
(B) 
Detention Requirements.
(1) 
Developments Requiring Detention.
Stormwater detention shall be addressed in the design, and implemented in the construction of, any new development or re-development having additional impervious cover of one acre or more, including any previous additions or modifications that increased the amount of imperviousness, and if the site of the development is located in an area where any of the following situations exist:
(a) 
If the 100-year stormwater runoff release rate from the proposed development exceeds the existing or programmed capacity of the MS4, then detention in such cases shall be designed and implemented to limit stormwater runoff to a rate that does not exceed the existing or programmed capacity of the MS4 for that site.
(b) 
If a proposed development is in an area where the MS4 is under-capacity by current design standards and the proposed 100-year stormwater runoff exceeds the existing stormwater runoff for the site of the development, then detention in such cases shall be designed and implemented to limit stormwater runoff rates to the pre-development runoff rate.
(c) 
If the proposed development is within the drainage area abutting the ecological boundary of the Spring Creek Forest Preserve or within the drainage area abutting the Spring Creek Forest Preserve boundary as defined by the Technical Standards, then detention in such cases shall be designed and implemented to conform to those provisions of the Technical Standards.
(2) 
Means of Detention.
Required detention shall be achieved through a means consistent with sound engineering practices and in a manner approved by the Director of Engineering. Such means may include extended dry detention, retention, underground storage and parking lot storage.
(3) 
Design and Construction.
The design and construction of all detention and retention facilities shall include provisions relating to functionality, stormwater quality, and maintenance as set forth within this Section 3.89 of this Division 8.
(4) 
Alternative - Storm Sewer System.
As an alternative to the provisions of this Section 3.89, a developer may elect to fund and construct an approved storm sewer system that will provide free outfall flow for the 100-year storm without negative impacts to the MS4 or to downstream or adjacent owners, in which event - upon completion and acceptance of the system in accordance with Article 6, Division 4 of this Chapter - the developer shall not have to otherwise comply with this Section 3.89 for those parts of the development that are served by the system.
(C) 
(Reserved)
(D) 
Retention Facilities & Amenity Ponds.
(1) 
Provisions.
A retention facility shall be designed and constructed to provide a permanent water storage volume and may provide additional volume as may be needed to temporarily store stormwater for detention purposes. A retention facility shall provide an outfall structure having a predetermined release rate.
(2) 
Amenity Ponds.
Amenity ponds may be constructed for aesthetic purposes, provided the amenity pond will not produce any adverse impacts to adjacent or downstream properties or to the MS4. Amenity ponds are not required to provide stormwater quality enhancement measures. However, if the amenity pond is used for any flood or stormwater quality purpose, then it shall be construed as a detention or retention pond, as applicable, and must comply with the applicable detention or retention pond provisions.
(3) 
Design & Construction.
Unless approved by the Director of Engineering, the design and construction of all retention facilities shall provide for flood control, stormwater quality, stabilized emergency overflow, and maintenance as set forth below and shall provide a minimum of one foot of freeboard.
(4) 
Minimal Accumulation.
All retention facilities and amenity ponds shall be designed to minimize the accumulation of unwanted vegetation, insect and algal growth, stagnant water, and odors. The Director of Engineering may require a retention facility or amenity pond to have a minimum pool depth or to be equipped with aeration devices or other measures designed to minimize nuisance conditions.
(E) 
Design Criteria.
(1) 
Professional Engineer.
All detention and retention facilities and all amenity ponds shall be designed by a professional engineer licensed to practice in the State of Texas.
(2) 
Design & Construction Approval Process.
A proposed detention or retention facility or an amenity pond shall be incorporated into the overall concept, planning, site development, and drainage plans for the development. The facility shall include appropriate landscaping and screening and be integrated into the development in a manner that enhances overall appearance and function of the site, especially in relation to the view from public streets. The design and construction aspects of all detention or retention facilities and amenity ponds shall be included in the landscaping plans and Site Engineering Drawings submitted to the City along with supporting calculations, documentation and such other plans, specifications and other information as may be needed for an appropriate review. Approval of the design and construction of facilities shall be accomplished through the City’s development review process and construction inspection process which will include the Development Review Committee.
(3) 
No Adverse Impact.
Detention or retention facilities and amenity ponds shall be designed so as not to cause any adverse impact to any property adjacent to, draining towards, or draining away from, the facility.
(4) 
Public Safety.
Detention and retention facilities and amenity ponds shall be designed and constructed taking into consideration the safety of the public and others. Items of site safety to be considered include the stability of embankments or cut slopes, temporary and permanent water depths, accessibility, fencing, and the compatibility of the facility with surrounding land uses.
(5) 
No Fences or Obstructions.
No fence or obstruction shall be located within a detention or retention facility, or within an amenity pond site without approval of the City.
(6) 
Design Capacity.
Detention and retention facilities and amenity ponds shall be designed so that the maximum release rate of all flood frequencies up to and including the 100-year storm shall not exceed the programmed capacity of the MS4 for the area. If the existing MS4 for the area is already under-capacity, then the facility shall be designed so that the maximum rate of stormwater runoff shall be no greater after development than prior to development.
(7) 
Additional Freeboard.
Unless otherwise approved by the Director of Engineering, all open detention or retention facilities shall provide an additional one foot of freeboard above the maximum water surface elevation together with a stabilized emergency overflow structure.
(8) 
Maintenance.
Detention and retention facilities shall be designed and constructed to include sufficient land and open space to provide for adequate maintenance of the facility consistent with this Section and other provisions of this GDC. A permanent detention pond easement containing the facility and the area surrounding the facility needed for maintenance of the facility shall be granted to the City. The acceptance of the easement by the City shall not obligate the City to provide care or maintenance for the facility in any manner. The City may require, but is not limited to:
(a) 
An all-weather access drive of at least ten feet in width with acceptable cross and longitudinal slopes from the facility to an adjoining public right-of-way or access easement;
(b) 
An all-weather access ramp to the bottom of the facility with acceptable cross and longitudinal slopes; and
(c) 
A level surface of a minimum of ten feet in width with acceptable cross and longitudinal slopes along the top of the facility, unencumbered by landscaping or other physical impediments.
(9) 
Slopes and Barriers.
(a) 
Earthen side slopes for detention and retention facilities and amenity ponds shall be constructed with a slope no steeper than 4:1 (horizontal-to-vertical). The Director of Engineering may require a slope stability study to be performed by a licensed engineer for any slope having an unusual height or in soils having unstable characteristics.
(b) 
A steeper side slope or wall may be allowed if approved structural measures are implemented to stabilize the slope and a handrail, fence, wall, or other barrier is constructed adjacent to the facility at a location and of a height, material, manner of construction, and appearance approved by the Director of Engineering and provided the barrier complies with other applicable codes and zoning requirements.
(c) 
The Director of Engineering may approve an alternative design to the requirements of this Subsection (E)(9) if strict adherence would unduly alter an existing natural feature such as a creek, waterway, natural pond, or stand of trees, and an acceptable alternative is proposed.
(d) 
Extended dry detention facilities shall include paved concrete flumes having a minimum slope of one-half percent for low-flow conditions. Unless otherwise approved by the Director of Engineering, a flume shall be installed between all inlet and outlet structures, and between point discharge locations (such as curb or swale outlets) and the bottom of the facility.
(10) 
Other Jurisdictional Requirements.
The design, construction, and operation of all detention and retention facilities and amenity ponds shall comply with all applicable federal, state, and local requirements regarding the design, construction, and operation of lakes, dams or other impoundments of water.
(11) 
Permanent Irrigation.
Unless otherwise approved by the Director of Engineering, every detention and retention facility and amenity pond shall be equipped with a permanent irrigation system having sufficient coverage to ensure the establishment and continued viability of living portions of the stabilized cover for the facility.
(F) 
Stormwater Quality.
(1) 
Improvement.
Detention and retention facilities shall be designed and constructed to improve stormwater quality. Detention and retention facilities shall be designed and constructed to detain the first one inch of a rainfall event for a minimum of twenty-four hours. This volume may be incorporated into, or operated in combination with, any additional storage volume needed for larger storm events.
(2) 
Alternative Methods for Improvement.
The Director of Engineering may approve alternate methods for detention and for achieving improved stormwater quality. Alternate methods may include utilization of mechanical filters, traps, or other pre-fabricated systems provided that the alternative methods prevent seventy percent or more of the total suspended solids, down to a one hundred micron-sized particle, from passing through the outlet structure and entering the MS4 and so long as the intent of the provisions contained in this article are met. Water quality enhancement measures shall be designed using the one-year, six-hour duration storm as defined in the most current NCTCOG “Integrated Stormwater Design Manual for Site Development.” If using a prefabricated stormwater screening device, the applicant shall provide supporting literature/data from the manufacturer indicating that the selected unit is properly sized for the project and that it complies with the intent of this GDC.
(G) 
Maintenance Responsibilities.
(1) 
Recurrent & Consistent Maintenance.
Detention and retention facilities and amenity ponds shall be adequately maintained on a recurrent and consistent basis by mowing, removing trash and debris, removing silt and sedimentation, grading, establishing and maintaining grass or other vegetation in order to provide stability for the structure, structural repair, mechanical repair, and such other activities as may be required to keep a facility covered by this Section 3.89 functioning in accordance with its original purpose and design. The affirmative defenses provided by Subsection 3.89(J)(3) do not apply to the requirements of this Subsection (G).
(2) 
Program for Permanent Maintenance.
The owner of a development containing a detention or retention facility, specifically including amenity ponds, shall establish a program that will provide for the permanent maintenance of the facility.
(a) 
The program may, for example, include the creation of a homeowners’ association or other permanently established entity having the ability to levy assessments or other means of providing a permanent source of revenue to fund the maintenance program and to perform, or cause to be performed, the activities required under the maintenance program.
(b) 
The maintenance program and the responsibilities to be undertaken pursuant to that program shall be described in a final operations and maintenance manual, a copy of which shall be provided to the City. The manual shall define the need for and purposes of the facility, describe the major components of the facility, create and mandate an inspection program and the ongoing maintenance procedures, identify all of the operational elements and features of the facility, and shall authorize the City to inspect the facilities for compliance. The contents of the manual shall be at least equivalent to the guidelines established in the “Garland Pond Operations and Maintenance Manual” (see the City’s Technical Standards).
(c) 
Additional requirements may be imposed due to unique or unusual circumstances as determined by the Director of Engineering.
(d) 
Any type of subdivision plat required for a particular development that contains a detention or retention facility shall delineate the maintenance responsibilities for the facilities.
(e) 
If a homeowners’ association is to provide maintenance for the facility, the maintenance responsibilities and a reference to the operations manual shall be included in the deed restrictions and covenants of the association.
(f) 
A signed and notarized Maintenance Acknowledgement is an integral part of the Operations & Maintenance (O&M) Manual required for all developments containing a detention, retention, or amenity pond. The party signing the document acknowledges and agrees to be responsible for the performance and maintenance of the detention, retention or amenity pond defined in the O&M Manual. A new, signed, and notarized Maintenance Acknowledgement shall be provided to the City any time there is a change in the responsible party.
(H) 
Construction Practices.
(1) 
Constructed During Initial Phases of Development.
If a detention or retention facility or amenity pond will be part of a development, the developer shall construct the facility during the initial phases of construction of the development, unless otherwise directed by the Director of Engineering, and shall ensure that the facility is fully functional as designed, prior to any paving activities, including the establishment of a stabilized cover, the living portions of which shall be maintained in a live, growing condition throughout the remaining phases of construction.
(2) 
Maintenance During Construction.
The developer shall adequately maintain the facility during construction including mowing, removing trash, debris, silt and sedimentation, grading, and maintaining all living components of the facility in a stable, growing condition.
(3) 
Letter of Conformance.
As a condition of, and prior to, a Letter of Final Acceptance being issued (Article 6, Division 4 of this Chapter 3) for a development containing a facility covered by this Section 3.89, the developer shall submit to the Director of Engineering a Letter of Conformance prepared by a professional engineer licensed in the State of Texas. The letter of conformance shall state that each facility within the development has been constructed in accordance with the lines and grades as approved on the design drawings and is functioning in accordance with the intent and purpose of the approved design.
(4) 
Adequate Stabilized Vegetative Cover.
No Building Permits (for a residential development) or Certificate of Occupancy (for a nonresidential development) for any development containing a facility covered by this Section 3.89 shall be issued until an adequate stabilized vegetative cover is in place on all completed facilities within the development. Any living portion of the stabilized cover shall be in a stable, growing condition.
(5) 
Funds Provided.
If, due to soil conditions, heartiness of seed or sod, unusually severe weather, inadequate or sporadic maintenance activities or similar circumstances, the long-term viability of a stabilized vegetative cover is questionable, the Director of Engineering may require the developer to deposit with the City a sum of money sufficient to fund the estimated costs of repairing, replacing, and maintaining the stabilized cover for a period of one year, to be used to establish a stabilized cover for the facility as originally contemplated. Costs may be estimated based upon the use of non-City equipment and labor. The City shall not be obligated to provide City-owned equipment or labor for such purposes. The deposit shall be submitted by the developer prior to the issuance of Building Permits or Certificates of Occupancy for the development, and shall be deposited in the City’s Stormwater Fund. Any portion of the deposit remaining after a period of one year shall be refunded, without interest, to the developer.
(6) 
No Alteration Without Approval.
Following construction, a facility shall not be altered without the written approval of the Director of Engineering.
(I) 
Landscaping Standards.
(1) 
General.
Detention and retention facilities and amenity ponds shall, through appropriate landscaping and screening, be integrated into the design of a development site in a manner that enhances the overall appearance and function of the site, especially in relation to the view from public streets.
(2) 
Review & Approval.
(a) 
Landscaping and screening of detention and retention facilities and amenity ponds shall be shown on plans required by applicable site development regulations. These plans shall be integrated into the Site Engineering Drawings (refer to Article 6, Division 1 of this Chapter 3) for the site.
(b) 
If a facility is to be constructed where there are no established landscaping or screening standards, then a landscape and screening plan will be required that is consistent with those required in other areas of the City.
(c) 
Approval of the design and construction of landscaping and screening shall be accomplished through the City’s development review process and construction inspection process which will include, but not be limited to, the Development Review Committee.
(3) 
Methods & Materials.
Methods and materials used for landscaping and screening shall be compatible with methods and materials used to meet site landscaping and screening requirements. Such facilities shall be landscaped using plant materials of a species, size, and spacing appropriate to the surrounding landscape and that do not result in blockage or impairment of the stormwater management function of the facility or associated maintenance activities.
(4) 
Open Space.
Detention and retention facilities and amenity ponds shall, where appropriate, be designed to serve an open space function in addition to the primary function of stormwater management. Organic shapes that blend into the natural landscape are preferred.
(5) 
Screening.
Detention and retention facilities and amenity ponds, and any associated fencing or barriers, shall be appropriately screened from the view of adjacent public streets or public ways. The material, height, construction, and appearance of the rail, fence, wall, or barrier, shall be approved by the Director of Engineering, shall be compatible with the overall character of the development, and shall be consistent with that allowed by other applicable codes or zoning requirements.
Trees, ornamental grasses, shrubs and groundcover shall be provided around the perimeter of detention and retention ponds within one hundred feet of a Type D or larger thoroughfare to minimize the visual impact from the street. The screening of the detention and retention ponds may be waived by the Planning Director based on site evaluation.
(J) 
Enforcement Remedies.
(1) 
Civil Remedies.
Pursuant to Sec. 54.012(4) of the Texas Local Government Code, Subchapter B of Chapter 54, Texas Local Government Code, providing for the enforcement of certain ordinances through the imposition of civil penalties and injunction, is hereby made applicable to any violation of this Section 3.89.
(2) 
Criminal Penalties.
A person who violates any provision of this Section shall be strictly liable for such violation regardless of the presence or absence of a culpable mental state and shall, upon conviction, be subject to a fine of not more than $2,000.00 per violation, per day.
(3) 
Affirmative Defenses.
Unless otherwise provided in this Section, it shall be an affirmative defense to a prosecution under this Section if:
(a) 
The detention facility, retention facility, or amenity pond that is the basis of the violation existed or was under construction prior to May 1, 2002; or
(b) 
The facility is located on property used primarily for agricultural purposes if the facility is at least three hundred feet from any public street, park, or property zoned for residential or commercial uses.
(Ordinance 6773 adopted 5/19/15; Ordinance 7055, sec. 28, adopted 5/7/19; Ordinance 7107, sec. 49, adopted 12/3/19)