Res 2016-137/approving a Water Master Plan to guide the future maintenance and extension of the City’s Water Infrastructure

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Alan Plummer Associates, Inc. Water Master Plan Update 2016 The City of San Marcos owns and operates a potable water distribution system to provide service to customers within its service area. The system is comprised of the following components: One 9 MGD Surface Water Treatment Plant (SWTP) Six active wells and well pumps at five separate sites Nine storage tanks (five of which serve as elevated storage to at least one pressure plane) and two clearwells at the SWTP Seven pump stations; and Six pressure reducing valves (PRVs) Over 1.3 million linear feet of mostly ductile iron or polyvinyl chloride (PVC) pipe The City completed a Master Plan for its water distribution system in 2003 to guide the growth and development of the distribution system. Since that time the system has seen significant changes and is anticipated to experience rapid growth in the foreseeable future with the development of two new major residential neighborhoods. For these reasons, the City retained Alan Plummer Associates, Inc. (APAI) to complete an update to the Water Master Plan. For the 2016 Water Master Plan Update, the hydraulic model software was upgraded from Bentley WaterCAD to Innovyze InfoWater which embeds within a geographic information systems (GIS) environment. Prior to evaluating future conditions, the hydraulic model needed to be updated and recalibrated to existing conditions. Field data collected in April 2014 were used to perform the updated model calibration. Advanced Metering Infrastructure (AMI) system. Having actual hourly consumption data for every meter in the system facilitated the distribution of demands and allowed for the development of accurate diurnal curve. As a result, strong calibration was achieved. An analysis of the existing system and its compliance with Texas Commission on Environmental Quality (TCEQ) requirements was conducted. The TCEQ adopted changes to its criteria in September 2014 that significantly changed the method for determining the number of connections in a system, which is used as the basis for determining capacity requirements. Under the old method, the number of connections was determined by the number of meters. Under the new criteria, each individual apartment unit is considered its own connection. For a City like San Marcos with a higher percentage of multi-family complexes this change is significant. The change increases the calculated number of connections from just over 12,000 to over 30,000. As a result of this change, the City received notice from TCEQ that they lacked sufficient water supplies per TCEQ regulations. However, the City has not come close to using the supplies available to it and applied for a variance to receive an Alternative Capacity Requirement (ACR). iii m:\projects\0600\022-01\doc\report\draft\draftmasterplan-v15_hef.docx