Luther Burbank Park Sport Courts Renovation

Here’s a look at progress since last week and upcoming construction activities.

Subgrade Remediation

Excavation of the existing subgrade is complete, and City staff anticipate all new subgrade material will be placed by early next week.

On Monday, the project team proof-rolled the base aggregate layer to ensure it will be strong enough to pave. A super solo dump truck hauling 10 yards of pea gravel and weighing approximately 35 tons total drove back and forth across the base while AESI assessed the impact. Only one small area needed to be strengthened after the proof roll, which is good news for the remediation work. DA Hogan inspected the base subgrade on Tuesday and approved moving forward with finishing the subgrade remediation.

Now FieldTurf is placing the final layers of rock material, which DA Hogan will inspect early next week.

New Perforated Drain Pipe for South Edge

As part of the new scope of work, FieldTurf is replacing an old drain pipe installed on the south border of the facility. The new pipe will catch groundwater draining off the hillside and help the Parks Operations team maintain the courts.

Upcoming Work: Paving and Planarity Test

Once the top subgrade layer is inspected and approved by DA Hogan, the project will move onto paving. Northwest Asphalt, the subcontractor handling paving, will install asphalt in two lifts. Following paving, the project team will conduct a flood test to confirm the planarity, or relative smoothness, of the court surface to ensure the asphalt install is consistent.

The best method for confirming court planarity is to conduct a flood test, which involves flooding the courts with 1” to 2” of water, then observing how the water drains/evaporates. If water pools in any areas, those areas are uneven and may be adjusted before construction is complete. This is a critical quality control step to ensure that the courts are constructed correctly and to avoid major repair or reconstruction needs in the future.

This project remains on track, and the courts are still anticipated to open for play in October. View construction photos here.

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

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.

Construction of the Luther Burbank Park Sport Courts Renovation remains suspended while the City works with the designer and contractor to finalize the scope of work to repair the failing subgrade prior to repaving the courts. The proposed change order is significant, so staff plan to return to City Council on September 3 to seek authorization and a budget appropriation to move forward with the work. Staff anticipate construction will resume by early September.

Details for joining the City Council meeting are available below.

The hybrid meeting will be live streamed on the City Council’s YouTube Channel beginning at 5pm.

Register to Speak: Individuals wishing to speak live during Appearances (public comment period) must register with the City Clerk at 206.275.7793 or cityclerk@mercerisland.gov before 4pm on September 3, 2024. Each speaker will be allowed three (3) minutes to speak. A timer will be visible to online speakers, City Council, and meeting participants.

Join by Telephone at 5pm: To listen to the meeting via telephone, please call 253.215.8782 and enter Webinar ID 878 1912 3930, Password 730224 when prompted.

Join by Internet at 5pm: To watch the meeting online via your computer, follow these steps:

1. Click this link (Webinar ID 8878 1912 3930; Password 730224)
2. If the Zoom app is not installed on your computer, you will be prompted to download it.
3. If prompted, enter Webinar ID 878 1912 3930, Password 730224.

Join In-Person at the Mercer Island Community & Event Center at 5pm: The meeting will take place in the Slater Room Council Chambers, 8236 SE 24th Street.

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.

The construction site was quieter this week, but progress continues to renovate the sport courts at Luther Burbank Park. Keep reading for this week’s construction update.

Drainage Investigation

On Monday, staff from the City’s Parks Maintenance, Sewer, and CIP teams met on-site to investigate the condition of the existing stormwater infrastructure. The team used a push camera to inspect the pipes from three entry points and confirmed they are still in good condition. Next week, FieldTurf will begin installing the new ACO Sport trench drain system, which will connect to the existing pipes to improve stormwater drainage at the facility. FieldTurf will also install a new storm drain cleanout to make it easier for Parks Maintenance to service the pipes in the future.

Conduit Installation

Service Electrical, a subcontractor of FieldTurf, also finished installing electrical conduit around the perimeter and up the middle of the courts last week, and FieldTurf backfilled the trenches this week. Junction boxes and electrical handholes will be installed later during construction.

As a reminder, no other electrical work is planned during this construction phase. Stantec Engineering is still developing a full lighting design, and an update will be shared on Let’s Talk when the design is ready to present to City Council for additional direction.

Other Work This Week

Excavation of the hill is complete, and FieldTurf also continued removing sawcut asphalt and other construction debris.

This project remains on schedule; view construction photos here.

Work continues to renovate the sport courts at Luther Burbank Park. Curious about all that dirt? Keep reading for construction updates this week.

Excavation Progress

FieldTurf continued excavating the hill south of the sport courts and laid the rock-stabilized construction access road. The contractor anticipates completing this phase of excavation by the end of the week. More work on the hillside will occur later during construction, including softening the hill slope and restoring the grass.

Other Work This Week

Demolition on the courts also continued this week. FieldTurf removed the existing tennis net posts and concrete footings; these will be replaced with new pickleball net posts as part of this project. The contractor also started trenching for electrical conduit, which is scheduled to be installed next week.

This project remains on schedule; view construction photos here.