The approach to the determination of site specific DCGLs, based on guidance contained in Preliminary Guidelines for Evaluating Dose Assessment in Support of Decommissioning” (NUREG-1549) is as follows:
• Step 1 – Determine the source inventory
• Step 2 – Define future land use scenarios
• Step 3 – Identify exposure pathways
• Step 4 – Develop conceptual model
• Step 5 – Determine DCGLs
• Step 6 – Perform sensitivity analysis
Beware of those quick answers, what scenario are you running? What effects does the local soil and water have on transport mechanisms? (you need to run a resrad determination.) If you are truely going to develop DCGL criteria- it may take you a while and then getting it justified will take longer. presentation to the stakeholders should be considered.
If you are developing scaling factors for surveys-develop your technical basis with instrument eff. for the energies of concern. That should only take a few days or week. Publish your technical basis and get it approved. If you are doing thumb rule frisking-(see first two replies) you are not developing a DCGL-you are making an operator aid. At that point each instrument will have a multiplier to compensate for the "number of clicks you hear" before you can release it. Technician review and some training should be provided.