Observations/Finding

At the request of the client’s representative, our AS ENGINEERING AND CONSULTING, LLC (ASEC) representative, Amin Azimi, visited the job site to observe the contractor’s work activities from a quality assurance standpoint. The purpose of the visit was to verify compliance with project drawings, specifications, applicable codes, approved material submittals, and to conduct QC testing in accordance with project requirements.

Observations for This Shift:

Work was in progress on Section 1A from STA 1020+00 to 1028+00. CWM was actively mixing lime with soil between STA 1020+00 and 1021+50. This area, which had failed the proof-roll twice previously, was being addressed again on its third attempt. In response, the contractor reprocessed this section by re-mixing the soil with lime and recompacting it. Additionally, lime treatment and mixing were underway in Section 1B between STA 1051+00 and 1056+75.

Proof Rolling Observation and Performance: A third proof-roll was performed on Section 1A between STA 1020+00 and 1021+50 on Runway 3R-21L using a fully loaded tandem axle truck. This section had been previously treated with lime, mixed to a depth of approximately 10 inches. Multiple passes were made across the subgrade. During the proof-roll, some yielding and deflection were observed in several areas within the center portion of Section 1A, where noticeable movement was detected, indicating that the subgrade still lacked adequate stability.

Note: One bucket of soil from the affected area was collected and transferred to the office for further evaluation after being mixed with lime.

Recommended Corrective Action: Based on field observations, it was recommended to undercut approximately 15 inches of the soft, unstable subgrade and replace it with graded aggregate base (GAB) to meet project requirements and ensure long-term stability.

Soft Area Dimensions:
The soft areas observed during proof rolling were recorded as follows:

• 44 ft x 13 ft

• 14 ft x 7 ft

• 51 ft x 6 ft

• 65 ft x 9 ft

• 23 ft x 7 ft

• 23 ft x 6 ft

• 76 ft x 7 ft

• 154 ft x 12 ft

Additional Personnel Present: The proof-roll was jointly observed by the undersigned (Amin Azimi), Kevin/Nova (QA Representative), and Brad (CWM Representative).

We appreciate the opportunity to be of service on this project. Should you have any questions regarding this report, please do not hesitate to contact us. We would be pleased to discuss our findings further.