Observations/Finding

As requested, a representative of AS Engineering & Consulting (ASEC) conducted a site visit to perform quality control inspection and testing services. Visual observation techniques were employed to verify compliance with project drawings/specifications, applicable codes, and approved material submittals.

2. Earthwork Activities

• Placement and compaction of backfill materials were in progress in the following locations:

  • Water line trench at the entrance/pit area.

  • Backfill behind Retaining Wall #1.

• During the observation, active placement of fill material was observed being performed in 1-foot lifts. Compaction was executed using a 12-ton sheeps-foot roller and trench compactors.

3. Compaction Testing

• Compaction testing was carried out using a Troxler nuclear density gauge in accordance with ASTM D6938.

• Additional verification was conducted with general probing, using a 3/8-inch diameter probe rod.

Test Results:

• Water Line Trench:

  • Did not achieve the specified minimum 95% relative compaction based on maximum dry density (MDD) per the Standard Proctor method (ASTM D698).

  • Moisture content exceeded the specified permissible range, indicating the soil was overly wet.

• Retaining Wall #1 Backfill:

  • Achieved the specified minimum 95% relative compaction per ASTM D698.

  • Our ASEC representative arrived on site to observe the placement of MSE retaining walls #1.It was noted that behind the block and in the cells, No. 57 stone was used.

    Every 2^nd course a geotextile fabric was placed followed by an 8-inch compacted lift.

    No. 57 stone was utilized 1-foot behind the block and within the cells.

    No remedial recommendation was made.

Notes:

• Moisture content was above the specified range. Under this condition, soils require scarification and aeration (moisture correction) prior to re-compaction. The contractor was notified but did not implement corrective action. Consequently, the trench was backfilled without achieving the required compaction.

4. Recommendations & Required Remediation

1. Undercut and Remove Non-Conforming Material
   Excavate the inadequately compacted zones around the water line to a depth sufficient to remove all non-conforming soils.

2. Moisture Conditioning
   Adjust the moisture content of the excavated soil to within ±2% of the laboratory-determined Optimum Moisture Content (OMC) before re-compaction

Thank you for the opportunity to support this project. Should you have any questions or wish to discuss these findings further, please feel free to contact us.