Laboratory Exercises Lead, compounds

Analysis of corrosion deposits from 6 lead pipes exhumed from City A indicated a dominance of Pb(II) compounds, which are more soluble than Pb(IV) compounds. This is consistent with the moderately high lead concentrations found in both LCR surveys and sequential sampling exercises. Despite pH elevation to 10.0 at the treatment works (which does not normally fall below 9.5 in the distribution network), 7 of the 9 surveys failed the LCR for lead over the period 2007 to 2011. The dominance of Pb(II) compounds also means that rapid laboratory plumbosolvency testing can be used in the quantification of M and E, and that the supply system should be amenable to orthophosphate treatment (albeit the transition characteristics of lead corrosion deposits under high pH conditions would have to be determined). 

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