Purgatory Creek Improvements
The objective of the Purgatory Creek Improvement project is to take a holistic approach regarding flood mitigation considering water quality and public space improvements. The project area consists of Purgatory Creek from the San Marcos River to the Flood Control Dam #5 located upstream of Wonder World Drive. During the first phase of the project (conducted during 2018 – 2019), conceptual designs including natural channel modifications, greenway trails, replacement of road crossings, utility modifications, permitting and approval requirements, and construction cost estimates were determined. Project conceptual finding and recommendations were presented in a Preliminary Engineering Report dated January 2019 and during various public meetings. See project presentation below for a summary of conceptual project findings and recommendations presented during the April 23, 2019 public meeting.
The next phase of the project consists of taking the conceptual ideas and start developing detailed design and construction documents. In order to control cost we will design and construct the project considering two project phases. The Phase 1 Area will be for the channel reach starting at the San Marcos River to near Johnson Avenue and the Phase 2 Area is from Johnson Avenue to Wonder World Drive.
We are currently developing the 30% level of design for the Phase 1 Area. The 30% design phase major tasks include data collection, environmental investigations, hydrological and hydraulic investigations, initiating the permitting requirements with various agencies, determination of easement and rights-of-way requirements, and preparation of design documents reflecting natural channel, road crossings, multi-use trails, and utility modifications. This phase of the project will also include conducting a public meeting with the date to be determined.
During the data collection task, our team will be conducting topographic and boundary surveys and environmental investigations. This could include the team identifying various points, trees, etc. with plastic ribbons, small flags or other non-permanent makings.
No-Mow Areas - In addition to help determine existing vegetation characteristics along Purgatory Creek, we will not mow along the creek until at least mid-Spring (May).
The Phase 1 Area 30% level of designs is scheduled to be completed by the end of 2020 and final designs to start during 2021.
Phase I of the project will produce a Preliminary Engineering Report (PER). The report will provide conceptual options to reduce water surface elevations during rain events, improve the water quality of run-off, address erosion and sedimentation issues, and explore greenbelt connectivity through the Purgatory Creek floodplain.
Basic concepts for the project were initially identified in the City's Drainage Master Plan.