project earthwork phases – role of the geotechnical report

When a substantial amount of compacted fill is placed prior to building a new structure, the IBC Code requires that a special inspector be present continuously during fill placement. The construction special inspections firm is often not the same firm that provided the subsurface investigation and geotechnical report, nor is it the designated Geotechnical Engineer-of-Record for the project. In this instance, the critical question is: How do the multiple firms involved with a project coordinate to ensure better code compliance?

Section 1705.6 of the IBC Code stipulates that the soils special inspector must verify the use of proper materials and procedures during earthwork operations per the provisions of the approved geotechnical report. The tabular formatting of soil special inspections in Table 1705.6 clearly conveys the requirements for determining soil bearing capacity and for testing inspection of soils for compacted fill. Inspections and tests prior to fill placement include verifying that the site preparation meets specified requirements, including proper excavation depth and removal of all deleterious material and other special requirements that the Geotechnical Engineer-of-Record deems necessary for the design.

Verification of the fill material and the placement operation are addressed in items 3 and 4 of Table 1705.6. Without observing and documenting that the proper material is used and the specified compaction techniques and lift thicknesses are employed, the design load bearing capacity may not be achieved.

It is clear that the code intends for communication channels between the project special inspector and the Geotechnical Engineer-of-Record, regardless of whether or not they are with the same agency.

IBC Chapter 17, Section 1705.6 Soils. The approved geotechnical report and the construction documents prepared by the Registered Design Professional (RDP) shall be used to determine compliance. During fill placement, the special inspector shall verify that proper materials and procedures are used in accordance with the provisions of the approved geotechnical report.

For more information or further enthusiastic discourse on topics of CODE, please contact Alan Tuck at: or 540.344.7939