Which two requirements must be met when installing anchor blocks in a trench?

The requirement for anchor blocks to extend across the full width and be keyed into the trench sides is essential for ensuring stability and support for the pipes being installed. This design not only helps prevent lateral movement of the pipes but also enables the anchor blocks to effectively transfer loads from the pipes into the trench walls. Keying the blocks into the trench ensures that they are securely anchored and less likely to shift or become dislodged due to soil movement or other external forces.

Additionally, having the blocks extend across the full width provides a more robust mounting point for the pipes, which can be subjected to varying pressures and forces during and after installation. This method enhances the overall integrity of the drainage system, as it prevents potential soil erosion or pipe displacement that could result from inadequate anchoring.

Other options do not align with best practices for anchor block installation in terms of stability and effectiveness.