San Marcos Development Code (effective November 3, 2021)

3 C H A P T E R

Subdivisions

2. Side slopes of channels shall be no steeper than four horizontal to one ver tical; and 3. All constructed and altered drainage channels shall be stabilized and vegetated as soon as practicable after final grading. B. Additional runoff velocity attenuation strategies and techniques detailed in the City of San Marcos Stormwater Technical Manual shall be utilized. Section 3.9.1.3 Impervious Cover Calculation and Limitations Paved roads, sidewalks, parking areas, parking lots, buildings and other impermeable construction covering the natural land surface shall be considered impervious cover. The methods to be used to calculate the percent of impervious cover created by the development of a parcel or tract of land are described in the City Stormwater Technical Manual. Note that the area of impervious cover for a surface may be reduced based on data acceptable to the Responsible Official showing that the surface has a significant degree of permeability. Section 3.9.1.4 Erosion Prevention and Highly Erodible Soils. Erosion prevention and restoration measures detailed in the City Stormwater Technical Manual shall be utilized to attain nature mimicking drainage objectives. Refer to the Technical Manual for a list of local soils that have a high potential for erosion based on Soil Conservation Service data. Section 3.9.1.5 Drainage Requirements During Construction During construction, on-site drainage shall be maintained so that water surfaces are not increased upstream or downstream of the site when compared to pre-project conditions unless fully contained within a drainage easement or designated right-of-way. Section 3.9.1.6 Drainage Improvement Responsibility A. Drainage improvements required by this Ar ticle shall be provided at the sole expense of the owner of the proper ty to be developed, unless otherwise expressly provided to the contrary in a subdivision improvements agreement. 4. Channel velocities shall be non-erosive.

B. Drainage easements shall be provided to the public by the owner of proper ty to be developed for the purposes of drainage master planning of all drainage improvements, open or enclosed, and all storm water flows to the limits of the one hundred (100) year floodplain as determined in accordance with anticipated fully-developed contributing area land use conditions and allowing continuous access for inspection, operation, maintenance and rehabilitation of all drainage improvements. C. At the discretion of the Responsible Official, the owner of the proper ty to be developed shall dedicate drainage improvements to the public in a right-of-way rather than a drainage easement. D. In determining whether drainage improvements should be dedicated to the public, the Responsible Official shall take the following factors into consideration: 1. Drainage improvements associated with a single development shall remain private; and 2. Drainage improvements that serve streets or other public proper ty or may serve multiple developments or provide regional detention/treatment shall be dedicated to the public. E. Drainage easement and right-of-way widths shall be specified by the City as necessary for inspection and maintenance of facilities as well as to accommodate areas anticipated to be inundated by stormwater. F. Full detention basin design may be deferred until the site development permit stage if the proper ty owner submits a “request for detention deferral” demonstrating an understanding of the implications of such design deferral AND the following notes are placed on the subdivision plat AND suppor ting documentation is provided.

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Amended: November 3, 2021 San Marcos Development Code