Deep excavation requires more than an estimate of how much water needs pumping. Its quality and available discharge routes also matter. If quality checks only begin once pumps are running, there is much less room to adapt the project.
Understand the site first
The review should cover past land use and nearby activities. Industrial processes and previous use of certain firefighting foams may warrant closer investigation of PFAS. This history does not prove contamination, but provides a useful starting point. EPA lists manufacturing, product use and releases into the environment among potential PFAS sources. EPA: sources and spread of PFAS.
A treatment plan needs more than one result
To prepare a solution, the client should collect expected average and peak pumping rates, work duration and available analyses. The designer should also identify space for temporary equipment, water storage options and the intended discharge point.
Dissolved PFAS need a different approach from sand or silt. For adsorption processes, ITRC stresses the importance of inlet water quality and potential pretreatment. Particles, organic matter and other constituents can influence process selection and performance. ITRC: treatment processes for PFAS-containing water.
Temporary treatment must follow construction progress
Include temporary treatment in the site plan. Define filter replacement access, sampling points and monitoring responsibilities in advance. Where inflow varies, plan for peak flows, equipment stoppages and outlet water that does not meet requirements.
A mobile unit trial can help verify the selected configuration. Its purpose is to obtain design data, so the objectives must be clear: outlet concentration, loading rate, treated volume, pressure monitoring and replacement intervals. The flow rate used in the pilot alone does not determine final system capacity.
From findings to a workable plan
The most useful outcome is a technical plan linking analysis, flow, equipment, monitoring and spent-media handling costs. This enables like-for-like quotation comparisons. Early water testing becomes part of construction preparation rather than a separate problem during excavation.
