Land Contamination: Technical Guidance on Special Sites: Acid Tar ...

4.2.3 Common mistakesIt is possible that coal tars could be mistaken for acid tars, as both will tend to give rise tobarren ground – the pH is the factor distinguishing acid tars. The mobility of acid tars andtheir propensity to flow upwards and laterally creates the potential for contamination of areaspreviously thought to be free of acid tars.4.2.4 Desk study check-list for acid tar lagoonsHave the following specialist information sources been approached?- Department of the Environment Industry Profile: Gas works, coke works and othercoal carbonisation plants, 1995.- Department of the Environment Industry Profile: Oil refineries and bulk storage ofcrude oil and petroleum products. 1995.Have historic maps and aerial photographs been studied to identify the location of formervoids that have been infilled?Has the likely source of the acid tars, in particular the nature of the process, beenestablished and any information on the production history and operational period ofproduction?Were any of the following features present on the site?:- black or dark brown staining, evidence of oozing tars or unvegetated areas;- weathered surface tars;- hollows/depressions;- clay/gravel/sand pits;- bunded areas;- odorous areas; and- areas of former fires.If yes to any of the above has the extent of these been established?4.3 Site Inspection and Investigation4.3.1 Site inspectionThe site inspection visits should always be based on the maximum available information thatcan possibly be obtained from the desk study phase and an initial conceptual model of the site.Although this is also the case with other types of contaminated land it is particularly importantwhen dealing with acid tar lagoon sites due to the explicit physical hazards that may bepresent. Site staff will need to be equipped with the relevant level of personal protectiveequipment (PPE) and trained accordingly (see Section 7 for health and safety aspects).As noted above, it may be possible by site inspection to gain an impression of the extent ofacid tar disposal from its surface expression. The aspects to look for include generally flatland (although this may have been modified by deposits of superficial wastes), absence ofR&D <strong>Technical</strong> Report P5-042/TR/04 21