(a)
Specific objectives.
(1)
Minimize increases in stormwater runoff from any development or redevelopment in order to reduce flooding, siltation, increases in stream temperature, and stream bank erosion and maintain the integrity of stream channels;
(2)
Minimize increases in nonpoint source pollution caused by stormwater runoff from development and redevelopment which would otherwise degrade local water quality;
(3)
Minimize the total volume of surface water runoff which flows from any specific site following development to not exceed the pre-development hydrologic regime to the maximum extent practicable;
(4)
Reduce stormwater runoff rates and volumes, soil erosion and nonpoint source pollution, wherever possible, through stormwater management controls and ensure that these management controls are properly maintained and pose no threat to public safety.
(b)
Exempted activities.
(1)
Any agricultural activity which is consistent with an approved soil conservation plan prepared or approved by the city, as applicable;
(2)
Additions or modifications to existing single-family structures;
(3)
Development and redevelopment that disturbs less than one (1) acre of land, provided it is not part of a larger common development plan (final authorization of all redevelopment projects will be determined after a review by the control authority);
(4)
Activities exempt from permit requirements of section 404 of the Federal Clean Water Act, as specified in 40 CFR 232 (primarily, ongoing farming and ranching activities);
(5)
Repairs to any stormwater treatment practice deemed necessary by the control authority.
(c)
Permit procedures and requirements.
(1)
No land owner or land operator shall receive approval of construction plans or building or grading permits required for land disturbing activities without first meeting the requirements of section 13.09.061(a) of this article.
(2)
The SWPPP, as discussed in section 13.09.061(c) of this article, shall be prepared to meet the city’s hydraulic requirements and be capable of handling design storm with a 2-year recurrence interval.
(d)
Waivers to stormwater management requirements.
(1)
Every applicant shall provide for stormwater management as required by this article, unless a written request is filed to waive this requirement. Requests to waive the stormwater management plan requirements shall be submitted to the control authority for approval.
(2)
The minimum requirements for stormwater management may be waived in whole or in part upon written request of the applicant, provided that at least one of the following conditions applies:
(A)
It can be demonstrated that the proposed development is not likely to impair attainment of the objectives of this article.
(B)
Provisions are made to manage stormwater by an off-site facility. The off-site facility is required to be in place, to be designed and adequately sized to provide a level of stormwater control that is equal to or greater than that which would be afforded by on-site practices.
(C)
The control authority finds that meeting the minimum on-site management requirements is not feasible due to the natural or existing physical characteristics of a site.
(D)
Nonstructural practices will be used on the site that reduce the generation of stormwater from the site, the size and cost of stormwater storage, and the pollutants generated at the site.
(3)
In instances where one of the conditions above applies, the city may grant a variance from strict compliance with these stormwater management provisions, as long as acceptable mitigation measures are provided. However, to be eligible for a variance, the applicant must demonstrate to the satisfaction of the control authority that the variance will not result in the following impacts to downstream waterways:
(4)
Furthermore, where compliance with minimum requirements for stormwater management are waived, the applicant will satisfy the minimum requirements by meeting one of the mitigation measures selected by the control authority. Mitigation measures may include, but are not limited to, the following:
(A)
The grant of an easement to be dedicated for preservation and/or reforestation. These lands should be located adjacent to the stream corridor in order to provide permanent buffer areas to protect water quality and aquatic habitat.
(B)
The creation of a stormwater management facility or other drainage improvements on previously developed properties, public or private, that currently lack stormwater management facilities designed and constructed in accordance with the purposes and standards of this article.
(C)
Entering into an agreement with the city for the granting of an easement or the dedication of land by the applicant, to be used for the construction of an off-site stormwater management facility. The agreement shall be entered into by the applicant and the city prior to the recording of plats, or, if no record plat is required, prior to the issuance of the building permit.
(e)
General performance criteria for stormwater management.
Unless judged by the city to be exempt or granted a waiver, the following performance criteria shall be addressed for stormwater management at all sites after development or redevelopment construction activities have been completed:
(1)
All permanent stormwater management practices installed during construction shall continue to control the peak flow rates of stormwater discharge associated with specified design storms and reduce the generation of stormwater. These practices should seek to utilize pervious areas for stormwater treatment and to infiltrate stormwater runoff from driveways, sidewalks, rooftops, parking lots, and landscaped areas to the maximum extent practical to provide treatment for both water quality and quantity.
(2)
All stormwater runoff generated from new development shall not discharge untreated stormwater directly into a jurisdictional wetland or local water body without adequate treatment. Where such discharges are proposed, the impact of the proposal on wetland functional values shall be assessed using a method acceptable to the control authority. In no case, shall the impact on functional values be any less than allowed by the U.S. Army Corp of engineers (USACE) or the TCEQ.
(3)
To protect stream channels from degradation, a specific channel protection criteria may be provided as approved by the control authority.
(4)
Certain industrial sites are required to prepare and implement a stormwater pollution prevention plan, and shall file a NOI under the provisions of the NPDES general permit. The SWPPP requirement applies to both existing and new industrial sites.
(5)
Prior to design, applicants are required to consult with the control authority to determine if they are subject to additional stormwater design requirements.
(6)
The city’s standard for calculation of peak flows shall be used for sizing all stormwater management practices.
(f)
Maintenance of structural BMPs.
The owner of a structural BMP installed pursuant to this section shall maintain and operate the BMP so as to preserve and continue its function in controlling storm water quality and quantity at the degree or amount of function for which the structural BMP was designed.
(g)
Nonstructural stormwater practices.
The use of nonstructural stormwater treatment practices is encouraged in order to minimize the reliance on structural practices. These nonstructural practices must be approved by the city and documented and shall remain unaltered by subsequent property owners.
(h)
Requirements for a SWPPP.
The SWPPP prepared in accordance with section 13.09.061 of this article shall include and identify the post-construction BMPs for the development.
(i)
Failure to maintain stormwater treatment practices.
If the requirements of maintaining post-construction stormwater treatment practices are not being met, the control authority shall direct the responsible party, in writing, to take action within 60 days to meet the maintenance requirements. If the condition of post-construction stormwater treatment practices become a danger to public safety or public health, the responsible party shall have 10 days to correct the condition after a written notice from the control authority. If the responsible party fails or refuses to correct deficiencies in the post-construction stormwater treatment practices within the applicable time frame after receiving written notice from the control authority, the city may, but is not required to, correct the deficiencies of the design standards or maintenance needs by performing, or causing to be performed, all necessary work to restore the facility to proper working condition on behalf of and at the expense of the responsible party. The city shall invoice the responsible party for the cost of such work and any penalties and the responsible party shall pay said costs and penalties within 30 days after receipt of the invoice. In the event that the responsible party fails to remit payment to the city, the city may impress a priority lien on the property upon which the post-construction stormwater treatment practices are located in order to secure reimbursement for the costs to the city. Such lien shall be perfected by filing in the office of the county clerk an affidavit identifying the property to be charged with such lien, stating the amount thereof, and making reference to this article.
(Ordinance 2016-01, ex. A, adopted 1/12/16)