Observations/Finding

As requested, the site was visited by our AS Engineering and Consulting (ASEC) representative for the purpose of providing quality control inspection and testing services. Visual observation techniques were employed to verify compliance with project drawing/specifications, applicable codes, and materials submittals. The following observations were observed on site this day:

A request was made by BBH to test the compaction around vault #3 at vault #1 area. The soil in the area was a mixture of soil types, and no optimum density-moisture ratio (proctor) was available. Due to the high moisture content, a 3/8-inch diameter probe was used, probing to a depth of approximately 6 inches (refer to attached photos).

Following additional compacting with a trench packer, it was determined that 12 inches of the top subgrade materials needed to be removed and replaced with M10 sand. After compaction of the north end, testing was conducted using a Troxler 3430 (serial #38069).

The proctor for M10 sand was an optimum dry density (DD) of 123.9 and a moisture (M) of 9.4%, with 90% compaction required.

The results of the initial test (#1) on the North end were as follows:

• Dry Density: 108.1
• Moisture: 7.3% (fail)

Following additional compaction and a retest (#1), the results were as follows:

• Dry Density: 111.0
• Moisture: 7.8%

QA agreed that these results were acceptable for the project requirements. It is important to note that no structures will be placed in this area.

No further observations were made on this day beyond the completion of these tasks.

Attached to this report are photos documenting the compaction testing process and the remediation efforts at the Vault #1 site.

Should you require further information or have any inquiries regarding this report, please do not hesitate to contact us.