San Marcos Development Code (effective Nov. 3, 2021)

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C H A P T E R

Environmental Regulations

Complying with the Edwards Aquifer Rules, Technical Guidance on Best Management Practices, RG – 348, Chapter 2. Section 6.1.3.2 Applicability A. In addition to the projects addressed in the San Marcos MS4 Ordinance in Chapter 86, Ar ticle 8, Division 2 of the San Marcos City Code, temporary erosion and sedimentation controls are required to be installed and maintained for the following activities that are or may not be covered by any type of watershed protection plan in the Edwards Aquifer Recharge Zone, Transition Zone, Contributing Zone within the Transition Zone or San Marcos River Protection Zone: 1. The construction or expansion of one single family home or accessory structure on a legally platted lot, or on an unsubdivided tract of land at least two acres in size, for which a legal description was contained in a deed recorded before March 1, 2000. 2. The installation or maintenance of utility lines by a governmental entity. 3. Landscaping activities involving more than 5,000 square feet of area of landscape installation. 4. The resurfacing of existing paved roads, parking lots, sidewalks, or other development-related impervious surfaces. B. Erosion and Sediment Control Monitoring. The Responsible Official will monitor stormwater discharges from these activities to evaluate the adequacy of the temporary erosion and sedimentation control measures. The Responsible Official may require the person performing the activity to use additional controls if the Responsible Official determines that the controls used by the person are inadequate to protect water quality.

agencies and the Responsible Official. All these projects shall be designed to stabilize existing conditions only. B. Excavation or filling. Excavation or filling shall be allowed only in accordance with Chapter 39 of the San Marcos City Code, and the following additional requirements: 1. The excavation or filling is necessary for the purpose of structural engineering or is in the area where a structure will be completed, including a building foundation; or 2. Excavation or filling, as demonstrated and cer tified by a registered professional engineer, will improve the water

quality of the runoff and/or stabilize an existing area of erosion and will continue the maintenance of flood and flow characteristics.

Section 6.1.2.5 Steep Slopes

The restrictions on impervious cover described in the table below shall apply in addition to impervious cover maximums identified in Chapter 4.

Criteria

Impervious Cover (Max)

Slopes of 15% - 25% gradient

35%

Slopes of > 25% gradient

20%

Division 3: EROSION AND SEDIMENTATION CONTROL FROM CONSTRUCTION SITES

Section 6.1.3.1 Erosion and Sediment Control Standards

A. The erosion and sedimentation control techniques for construction activities detailed in the San Marcos MS4 Ordinance in Chapter 86, Ar ticle 8, Division 2 of the San Marcos City Code and the City Stormwater Technical Manual shall be utilized to reduce environmental impacts from development and must be installed prior to commencing construction; be maintained during construction; and not be removed until vegetation is established and the construction area is stabilized. B. All temporary erosion and sedimentation controls for projects within the EARZ must meet the applicable standards and requirements of the TCEQ Edwards Aquifer Protection Program,

Division 4: POST-CONSTRUCTION STORMWATER PERFORMANCE STANDARDS

Section 6.1.4.1 Stormwater Quality and Stream Protection

A. Stream Protection Volume (SPV). Stream Protection Volume is based on the amount of runoff produced over the developed area from the listed rainfall amount identified in Section 6.1.4.1(C).

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San Marcos Development Code Amended: November 3, 2021