Luther Burbank Park Sport Courts Renovation

Excavation of the existing subgrade continued this week. FieldTurf is removing old material in sections, then backfilling with new crushed rock to build the stronger base for paving. As the contractor works from east to west, we are seeing the excavation depth to reach strong soils decrease, which City staff anticipated based on the subgrade tests performed by AESI in July. Subgrade remediation will continue through next week, weather-permitting.

This project is back on track, and the courts are currently planned to reopen for play in October. View construction photos here.

On Tuesday, September 3(External link), the City Council authorized a budget appropriation to remediate the failing subgrade and complete the Luther Burbank Park Sport Courts Renovation. (AB 6533(External link))

FieldTurf, the City’s contractor, has resumed construction, starting with removing and disposing of the existing asphalt. After removing the asphalt, FieldTurf began excavating the subgrade under the consultation of AESI, the City's geotechnical consultant. AESI is monitoring excavation to ensure the contractor only removes as much weak material as necessary to reach stronger soils. Once excavation is complete, new material will be laid and compacted to create a stronger base for asphalt paving.

This project is back on track, and the courts are currently planned to reopen for play in October. View construction photos here.

Based on the testing results from last week, it has been determined that the failing subgrade must be replaced before court paving can be completed. This additional work requires a change order for the construction contract and includes:

• Removing more of the old asphalt surface;
• Removing weak soils from the subgrade; and
• Building a stronger base with new material.

Preparations for paving the courts will resume after the base is repaired. While this project was ahead of schedule earlier this month, the construction pause and the scope of the subgrade remediation unfortunately delay completion. Staff now anticipate opening the courts by early October. User groups have been notified that the facility will not be available for play in August as originally planned.

Staff are still finalizing the change order with DA Hogan and FieldTurf. The new project timeline and regular updates will be posted on Let’s Talk once construction can restart.

While prepping the sport courts for the asphalt overlay last week, City staff and the contractor discovered that the subgrade, or soil that the existing pavement is built on, is failing in some areas. Construction has paused so Associated Earth Sciences Inc. (AESI) could perform subgrade testing and provide recommendations for remediation.

This week, AESI used a dynamic cone penetrometer, or DCP, to test soil strength in five areas on the courts. A DCP device consists of a steel rod, a hardened conical tip, and a standard weight hammer. During testing, the hammer is raised to the top of the rod and dropped to drive the rod into the ground. The DCP of the soil is recorded after each blow of the hammer and correlated to standard measures of soil strength. After identifying the DCP measurement, the consultant used a t-handle probe to confirm the depth to firm soils.

Once the soil test results and remediation recommendations are received, City staff, DA Hogan, and FieldTurf will evaluate the project design and adjust as needed to strengthen the subgrade.

Here’s a look at construction progress at the Luther Burbank sport courts since the last update.

• FieldTurf finished installing the trench drain system on the east side of the courts.
• The conduit running the south fence line and the electrical handholes were installed.
• A few extra sections of the existing surface were removed, and NW Asphalt patched the saw cuts with new asphalt.

Now staff and DA Hogan, the City’s architect for this project, are completing inspections to confirm the courts are ready for the asphalt overlay. This project remains on schedule; view construction photos here.

The contractor began installing the new trench drain system on the east side of the courts this week. After installation is complete, the courts will be cleaned and prepped for paving. That phase includes installing new asphalt in the sawcut areas, then overlaying the entire court area with new asphalt.

There will be no Let’s Talk update next week due to the Fourth of July holiday. The next update will be posted on Thursday, July 11.

This project remains on schedule; view construction photos here.