Coleman Engineering prepared route alternatives analyses and selection; preliminary and final design and CEQA environmental document preparation for a four-phase replacement of approximately 11,000 feet of the City’s 10-inch diameter raw water pipeline from Waterfall and Newman Gulches to the City’s water treatment plant. The pipeline is nearing the end of its service life and crosses sections of steep, heavily wooded terrain and landslip-prone gorges. There is also sensitive riparian environment within the California Coastal Zone to be crossed. The planning and route selection stage included identification of options; creation and refinement of evaluation criteria; establishment of an evaluation methodology in conjunction with the City and stakeholders; weighting factors; a quantitative numerical matrix to sum the evaluation criteria, and a sensitivity analysis workshop with the City. Evaluation criteria included construction cost, life cycle cost, construction schedule, easement acquisition, ease of operation and maintenance, constructability, geotechnical and geologic hazards, environmental impacts, ease of permitting, and public impacts.
Key Challenges & Solutions
- Potential environmental impacts on the project are significant, with sensitive riparian environments; steep, heavily wooded terrain; and sensitive species habitats. The need for extensive environmental permitting and consultation was anticipated at the start of the project, and the Project Practicality Report for the planning and route selection phase was prepared in detail to be a defensible document for subsequent CEQA studies and permitting by regulatory agencies.
- Accessibility within the steep, heavily wooded terrain will significantly impact construction viability, techniques, and cost. Our team included an experienced former contractor who provided detailed input for route selection and constructability-based cost estimating.
February 14, 2022