High Fe biosolids composts were added to As and Fe contaminated orchard soils in both a lab study and a field experiment. Reductions in metal availability were measured using a version of the PBET extraction. Reduction in bioavailability for both Pb and As were observed when high Fe compost (Fe added during wastewater treatment) was added to soil at a 100 g compost per kg soil rate. Addition of Fe to biosolids following wastewater treatment but prior to composting did not result in the same level of reduction in metal availability as addition of Fe during the wastewater treatment process. Speciation of Fe in the compost was studied using XAS microbeam analysis. Both the nature of the adsorbing surface and the association of Pb and As with Fe will be discussed.