Graham Hill WTP Concrete Reservoir

Santa Cruz, CA

As the existing four post-tensioned concrete tanks reach the end of their service life, the City of Santa Cruz has decided to replace the tanks as well as their related equipment, piping, and other appurtenances. Also included in this project is the construction of a new electrical building, several retaining walls, and the widening of the access roadway. This project aims to do more than just replace the existing tanks but also increase operational flexibility and redundancy with improvements to pump stations and piping layouts.

This project has several key components:

  • Replace the 1.0 MG filtered water storage tank
  • Replace the 0.7 MG wash water reclamation tank
  • Replace the 0.7 MG sludge storage tank
  • Replace and relocate the reclaim pump station and wash water supply pump station
  • Install new decant port effluent pump station and sludge pump station vault
  • Construct new electrical building
  • Widen existing roadway

Twining is providing materials testing and inspection services. Our scope includes the following:

  • Review of concrete mix designs
  • Review of grout/mortar mix designs
  • Quality control during construction including:
    • Structural steel in both the field and shop
    • Concrete sampling and testing
    • Structural masonry
    • Earthwork
    • Controlled low strength material (CLSM) (backfill)
    • Asphalt placement
    • Drilled and epoxied anchor bolts
    • Coatings


Pacific Hydrotech Corporation

Services Provided

  • Materials Testing Laboratories
  • Special Inspections; Materials Testing Laboratories

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