What should be done to sumps or accessible pits that connect to soil gas?

The appropriate action regarding sumps or accessible pits that connect to soil gas is to seal them to the extent possible without compromising water control. This is important to mitigate potential radon entry points while still ensuring proper drainage and managing groundwater effectively.

Sealing gaps can significantly reduce the entry of soil gas, including radon, into a structure. However, it is crucial to be mindful of water control when performing this sealing. If sumps are sealed too tightly without consideration for water drainage, they may trap water, leading to flooding or other moisture-related problems within a building's foundation. Therefore, the solution must strike a balance between preventing radon infiltration and maintaining adequate water management systems.

Other options do not present this balanced approach. For instance, sealing completely without ensuring water control could create issues with water accumulation. Leaving them open for ventilation might allow soil gas, including radon, to enter the building, negating the purpose of mitigation. Simply replacing them with solid concrete does not address the radon issue effectively and may present its own set of water control challenges. Thus, the correct approach emphasizes effective sealing while considering and maintaining proper water management solutions.