Nohl Canyon Reservoir

The Project.

The City of Anaheim needed to increase its storage capacity and decided to do so by converting the obsolete open-air Olive Hills reservoir to a 20-MG buried concrete reservoir, with the backfilled area utilized for public recreation. Based on this conceptual design, Leighton was retained by the City of Anaheim to prepare a geotechnical investigation to support final design of this buried concrete water tank. This design was eventually determined to be too risky and costly due in part to geologic conditions. Working with the City and design team, Leighton provided additional engineering and analysis that resulted in the decision to construct a 10 MG tank to reduce cost impacts of the design challenges.


City of Anaheim


Anaheim, CA


  • Geotechnical
  • Geotechnical Testing

Project Fact:

The City of Anaheim studied several alternatives to provide needed water storage while meeting the requirements of DSOD and providing an enclosed reservoir for improved water quality and reliability.

The Leighton Solution.

Leighton responded to the technical challenges of the site and concerns of the surrounding communities to assist the City in completing the CalGEO 2010-2011 Large Project Award-winning project.

Alternatives considered at various times included use of soil nailing for slope stabilization during grading; pile foundations for support of the DYK tank; alternate grading recommendations for foundation support; and detailed engineering geology and geotechnical engineering analysis of slope stability. Conversion of the reservoir required installation of groundwater observation wells and slope inclinometers to assess stability of the proposed slopes that included adverse geologic bedding.

Equally important was communication conducted with local residents, as requested by the City, and care exercised to understand and allay their concerns regarding a catastrophic slope instability event and the potential for loss of property. Slope failures had previously occurred in one adjacent neighborhood, which was subsequently rebuilt adjacent to this reservoir.