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Proposal for Professional Engineering Services Sessom Creek Erosion Remediation Evaluation ATTACHMENT A SCOPE OF SERVICES This scope of services includes a stream erosion assessment, preliminary designs and cost estimates for discrete locations to address erosion needs along Sessom Creek from the outfall of Sessom Creek to the San Marcos River to approximately Peachtree Street. Erosion is part of a natural process in a stream system; however, changes within the watershed, such as urbanization, can accelerate and exacerbate the natural process threatening water quality, ecosystems, private property as well as municipal infrastructure. Sessom Creek is in state of adjustment from the effects of urbanization and the initial assessment is, overall, that it is in a state of degradation. Remediation at discrete locations is necessary to stabilize excessive areas of erosion that threatens property and infrastructure. While drainage and water quality planning efforts by the City are scheduled in 2013, stream erosion will not be addressed. Erosion on Sessom Creek is a priority for the City which is addressed in this scope of services. The following sections describe the background, work breakdown structure and deliverables. BACKGROUND Sessom Creek drains approximately 0.63 square miles (approximately 400 acres) as it flows into the headwaters of the San Marcos River. The upper portion of Sessom Creek consists of a natural channel with a grass /rock bottom and heavy brush on the side slopes. The lower portion of Sessom Creek (downstream of LBJ Drive) is highly urbanized and includes a system of culverts, bridges, and segments that are lined in concrete. Land use includes single family in the headways and retail /commercial/education in the lower portion of the watershed. Flood Conditions - Sessom Creek is not a studied stream in FEMA's effective Flood Insurance Study (FIS); however, in 2007 the City of San Marcos commissioned a flood protection planning study and the development of a flood protection plan with financial assistance from the Texas Water Development Board. Sessom Creek presents a significant flooding risk to the areas adjacent to Sessom Drive and Texas State University during more extreme events when flow is not contained within the banks of the creek. The flood protection plan included several proposed culvert upgrades to improve the level of service at Sessom Drive at Aquarena Springs Drive, Peques Street, Texas State Pleasant Street, and LBJ Drive. University maintenance driveway, Page I of 7 September 18, 2012 Revised October 9, 2012