Ord 2016-050/revisions to the San Marcos City Code of Ordinance Chapter 39: Flood Damage Prevention Ordinance

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article, which demonstrates that reclamation or alteration of the floodplain 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 of the waterway, and which provides for protection of altered areas during and after alteration and development of adjacent land. Sec. 39.051. Floodplain easements. Appropriate drainage and flood maintenance easements shall be granted to the city prior to approval of a plat application on all floodplain land that remains following reclamation authorized under the approved qualified watershed protection plan. Sec. 39.052. Stream velocity. Alterations of the floodplain shall not create an erosive water velocity on- or off -site. The mean velocity of stream flow at the site after fill shall be no greater than the mean velocity of the stream flow under existing conditions. No alteration to the floodplain will be permitted which would increase velocities of flood waters to the extent that significant erosion of floodplain soils will occur either on the subject property or on other properties whether adjacent, upstream or downstream. Mean channel velocities that exceed six f.p.s. are considered to be erosive. Sec. 39.053. Side slopes. (a) The following standards apply to slide slopes: (1) To insure maximum accessibility to the floodplain for maintenance and other purposes, and to lessen the probability of slope erosion during periods of high water, maximum slopes of filled area shall not exceed four feet horizontal to one foot vertical. (2) Soil retention blankets must be installed on all fill slopes to promote the revegetation of the slope. (b) Rock gabion construction, decorative stone faced reinforced concrete rip -rap or an approved equal erosion protection measure is required on slopes steeper than 3:1. (c) Vertical walls, terracing and other slope treatments will be considered only as 1) part of a landscaping plan submission, and 2) if no unbalancing of stream flow results. (d) Grass cover is required for all cut and fill slopes 3:1 or flatter. Fill slopes shall be seeded with at least three herbaceous species including grasses, legumes, and wild flowers, selected from the following list. A minimum of three of the species from the plant list in the Technical Manual for this Section shall be used, one of which must be a flowering species.