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.

Work continued at Pond 3 with backfilling operations around the previously installed underground stormwater detention pipes. On-site fill was placed in controlled lifts of approximately 6 to 8 inches. Each lift was compacted using a sheep-foot roller after the placement of precast concrete manhole structures. The manhole was aligned to design elevation and orientation. Backfill material was placed uniformly around the structure and compacted. Final compaction around the manhole appeared to meet job specifications based on visual observation and roller response.

At Pond 2, backfilling operations resumed around the installed corrugated metal pipes (CMP) forming the underground detention system. Soil was placed in 3 to 4 lifts, each approximately 6–8 inches thick and compacted using a sheep-foot roller.

At Pond 1, excavation activities were carried out to prepare for end treatment installation. The trench was excavated to the required design depth. A header was installed at the end of the detention pipe run to provide structural support and controlled discharge.

Following installation, backfilling was performed in thin lifts. However, compaction testing failed in certain areas due to high moisture contents in the soil.

Simultaneously, earthwork operations continued at sd2 910-sd2 920. Soil was placed in 2 to 3 controlled lifts, each approximately 6–8 inches thick and compacted using a sheep-foot roller. The compaction effort met job specifications.

Recommendations:

• Remove organic and unsuitable material from wet or unstable areas prior to backfilling.

• Scarify and aerate wetter than optimum moisture soils prior to placement and compaction.

• Increase the number of sheep-foot roller passes.

• Maintain strict lift thickness control (6–8 inches maximum) in confined trench areas.

We appreciate the opportunity to be of service to you on this project. If you have any questions regarding this report, please feel free to contact us. We will be more than happy to discuss it with you.