The Project.
With only one high school in the Carlsbad Unified School District that was over capacity, a second high school (Sage Creek) was the stimulus to secure a local bond measure. The District wanted to begin construction in just three years, so before the votes were all counted, a 52-acre site was selected and Leighton was completing both environmental and geologic hazard studies.
Client:
Carlsbad Unified School District
Location:
Carlsbad, CA
Services:
- Environmental
- Geotechnical
- Geotechnical Testing
Project Fact:
This new high school is making an impact with its S.T.E.M. Elective Pathways in Biomedical Science and Engineering. Maybe a Sage Creek grad will be a geotechnical engineer at Leighton some day!
The Leighton Solution.
The former agriculture use of the land set a course for a PEA which identified hydrocarbons and arsenic. Completion of a Supplemental Site Investigation set specific clean-up levels for arsenic in concurrence with DTSC.
As there had been other setbacks to the construction schedule, Leighton requested and received a “partial site approval” from the DTSC to allow the District to proceed with construction on portions of the site that the DTSC determined was not impacted by a release of hazardous materials.
The site also had some geologic constraints to overcome to accomplish the District’s objectives. Stereoscopic photo analysis mapped a landslide which was confirmed with subsurface studies. To fully maximize the site, slopes up to 100 feet in height and over 2,000 lineal feet of retaining wall were incorporated into the site design.
Preliminary recommendations provided by Leighton provided for design of conventional and segmental retaining walls. Site-specific seismic ground motion analysis was performed for consideration in the dynamic slope stability analysis and for development of design parameters for retaining walls. Cost analyses performed by the Lease-Leaseback builder identified a potential savings on the order of $1 million by use of segmental retaining walls as recommended by Leighton.
Leighton provided supplementary recommendations and design review to successfully gain approval from CGS and DSA for 1,500 lf of retaining walls that were changed from conventional to segmental retaining walls. Designs incorporated the latest design guidance from NCMA, accounted for the backfill flooding along a storm water channel, and met the more rigorous seismic design requirements of DSA.
