Hi all, 
I’m currently studying for my MSc in Contaminant Hydrogeology and I’m in the process of completing my dissertation, ‘A Cost Benefit Evaluation of Site Investigation for Contaminated Land to Reduce Uncertainty in Risk Assessments.’

In summary, my dissertation will involve a comparison of the outputs generated from deterministic and probabilistic use of the Remedial Targets Methodology (RTM) based on a contaminated site to understand the uncertainty currently present within different risk assessment approaches.  I then aim to complete a sensitivity analysis to indicate the sensitive parameters present when using the RTM and evaluate them in terms of cost to gather such information to produce a guide for site investigation.

I’m working on a site as a case study where preliminary site investigation has been undertaken however, very little data is available which is required to be entered into the RTM – therefore I now face a battle with the literature out there!

I’m posting on here as I would like some guidance on where to look for data or to obtain potential values you may have/know based on your past experience.  I would also like any information based on experience for costs of site investigation as well as remedial costs.  The information I would like any advice or guidance on is detailed below:

- TPH contamination is mainly in the range C12-C40; what would be a good substance to base the RTM on?  Such that I can obtain Koc values/henry’s law constant/half lifes.
- A good source for henry’s law constants and a method to convert these from 10ºC to 20ºC for the chosen substance to model the TPH’s upon.
- A good source for koc values for the chosen substance to model the TPH’s upon.
- A good source for the half life of the chosen substance to model TPH’s upon.
- An EQS for ammoniacal nitrogen for freshwater and a reference if possible.
- Half life degradation rates for ammoniacal nitrogen and a reference f possible.

I also require information on costs of site investigation and remedial actions (which don’t really seem to be present in literature).  Therefore if you could provide any prices based on experience (approximate figures will do!) that would be appreciated so I can put my cost benefit evaluation into context.  Such information I require is:

- Costs to drill boreholes within Made Ground.  In the site investigation these were window samplers, which I assume are direct push methods.  I assume auger drilling could also be used?  Therefore any costs for these – only upto a depth of 5m or so.
- Costs for testing of the following:
- Water/air filled porosity 
- Bulk density/dry bulk density 
- Moisture content 
- Particle size density 
- Kd values – costs of lab leachate tests
- Foc values 
- Koc values 
- Hydraulic conductivity tests – pumping tests/slug tests/tracer tests/grain size analysis
- Half life degradation of contaminants – lab tests
- Cost to remediate the site by means of:
- Excavation of 10,000m3 of Made Ground (including disposal costs) and any costs required for dewatering
- Re-surfacing an area of 5,000m2 with concrete
- Implementation of a surface water management system over an area of 5,000m2.
- Installation of a pump and treat system
- Costs incurred in terms of fines for pollution of an already impacted groundwater body.
- Costs incurred in terms of fines for pollution of a water course.

I also have a question relating to the EA’s remedial targets methodology:

In the porosity calculator which I’m using to calculate air filled porosities.  It states the moisture content should be %wt.  However, I am unsure whether is this correct as a moisture content of 25% calculates an initial saturated of >100%.
I feel that the moisture content should be entered as a fraction, i.e. 0.25?

Thanks you all for your time,

Leigh.