Construction of Technosols offers interesting alternatives to two current problems in the city of VitoriaGasteiz

(Spain): waste recycling and degraded plot recovery. To evaluate the viability of their use, 6

types of Technosols were created by mixing four different byproducts from municipal waste treatment

plants. The less than 40 mm size fraction material from the municipal construction and demolition waste

treatment plant was used as the main ingredient, bio-stabilized material from the solid urban waste

treatment plant mixed with triturated pruning was used as organic matter input, recycled bentonites and

topsoil from the public plots of Vitoria-Gasteiz (Spain) completed the mixture. Mixes were prepared

in triplicate and installed in 48 m2

cells along with another 4 control cells containing only one of the

ingredients at the municipal landfill of Gardelegui. A monitoring program for different parameters on

soil, eluates and natural leachates was established to test the Technosols’ capacity to sustain vegetation

without negative impacts on the environment. The final objective is to test their ability to restore unused

municipal plots. Results from the first year show that Technosols are a suitable option for degraded sites

restoration and green infrastructure support. All controlled parameters on soil are within the limits set by

autonomic legislation for land use as public park. The eluate analysis concludes for all studied parameters

that all mixes would be classified by legislation as inert waste, except for the sulphate concentration

(which exceeds the inert waste limit of 1 000 ppm), that currently would label the soil as non-hazardous.

In the natural leachate analysis strongly basic pH values were present above 9.5, the limit allowed in

Royal Decreet 849/1986, but acidified throughout the year moving towards neutrality, with final values

between 7.31 and 7.51. Leachate from CDW30, TS15 and RB30 Technosols showed not allowed values

with respect to sulfates and Fe during the last sampling, surpassing the limits of 2 mg/l and 2 000 mg/l

respectively. All studied Technosols presented a low ecological potential risk (RI < 150) for heavy metals

in soil and eluates.