Transition sumps installed should always have a raised concrete apron not less than how many inches around the grade opening for durability?

The correct answer is based on industry standards for the installation of transition sumps, which are critical components in underground storage tank systems. A raised concrete apron around the grade opening serves several important functions: it provides support, helps with drainage, and adds a layer of protection against environmental elements.

The specified dimension of a 24-inch apron is essential for ensuring that the area remains stable and durable over time. This width is adequate to prevent soil erosion around the sump and to accommodate any necessary maintenance activities while ensuring the integrity of the installation. A raised concrete apron of this size also assists in minimizing the risk of contamination by directing surface water away from the opening.

Implementing a foam case for transition sumps to a lesser width could compromise the structural integrity and durability of the installation, possibly leading to increased maintenance and repair costs in the future. Hence, a minimum apron size of 24 inches is widely accepted as a standard that balances functionality with durability in the installation of transition sumps.